Publications scientifique dans le domaine des technologies du 04-2011

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» "BOC-Gated-PRN" A Multipath Mitigation Technique for BOC(n,n) Waveforms

Résumé:
A new, unambiguous, cost-effective discriminator is introduced that maintains the multipath mitigation property of binary offset carrier (BOC) $(n,n)$ signals such as BOC$(1,1)$. The multipath mitigation performance of different discriminators is evaluated, including the "BOC-PRN $(R{E+L})$" discriminator proposed previously by the authors, and examines the associated noncoherent tracking structures. The new discriminator is based on gating of the correlation reference function and on the concept of BOC-PRN, where the BOC signal is correlated not with itself but with the pseudorandom noise (PRN) code only, and is a compromise between low complexity and high performance in terms of multipath and code tracking.

Auteurs: Wu, Jinghui;Dempster, Andrew G.;

Apparue dans: IEEE Transactions on Aerospace and Electronic Systems

Date publication: 04.-2011, volume: 47, issue:2, pages: 1136 - 1153

Editeur: IEEE

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» "Quality...It's Not an Add-On! [Essay]"

Résumé:
The value of quality for any product cannot be over emphasized. From the inception of a product in Market requirements to Engineering specification, vendor selection and qualification, manufacturing assembly processes, and review of customer satisfaction ratings, quality impacts a company's success or lack thereof. It can't be added on or tested in, quality needs to be involved along the entire development process. Failure to do so practically ensures problems in the field-at the customer's location. You don't want problems coming from that direction, so fix "quality" into the product from the very beginning.

Auteurs: Floyd, R.E.;Spencer, R.H.;

Apparue dans: IEEE Potentials

Date publication: 04.-2011, volume: 30, issue:2, pages: 8 - 9

Editeur: IEEE

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» ‘Griffiths phase’ versus chemical disorder in low-doped manganites: La0.9Sr0.1MnO3 crystal revisited

Résumé:
Magnetic properties, electron paramagnetic and ferromagnetic resonance were studied in the vicinity and above ferromagnetic-paramagnetic (FM-PM) phase transition of the La0.9Sr0.1MnO3 crystal. It appears that complex chemical/structural disorder inherent to manganites influences strongly on both magnetic and resonance properties of this crystal. In particular, it changes the nature of a FM–PM transition to the first- or mixed-order one and induces FM clustering in their PM state. The latter effect results in coexistence of resonance signals, and non-linearity of the PM inverse magnetic susceptibility versus temperature. This model seems to be much more realistic for description of the PM state in La0.9Sr0.1MnO3 than an idealized Griffiths phase approach.

Auteurs: Rozenberg, E.;Auslender, M.;Shames, A.I.;Felner, I.;Mogilyansky, D.;Mukovskii, Ya. M.;

Apparue dans: Journal of Applied Physics

Date publication: 04.-2011, volume: 109, issue:7, pages: 07D902 - 07D902-3

Editeur: IEEE

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» “In-plane” and “out-of-plane” uniaxial anisotropy of amorphous precursors and nanocrystalline FeCuNbSiB alloys

Résumé:
The “in-plane” and “out-of-plane” angular dependence of ferromagnetic resonance data demonstrate that both cubic and uniaxial magnetocrystalline anisotropies are present in FeCuNbSiB nanocrystalline alloys. The intergrain exchange interactions, mediated by the spins of the amorphous ferromagnetic matrix, are unable (able) to average out the local uniaxial magnetocrystalline anisotropy of the Fe3B and Fe2Si nanocrystalline grains and, thereby, lead to the magnetic hardening (softening) in the early stages of nanocrystallization in most of the compositions (remaining ones).

Auteurs: Basheed, G. A.;Kaul, S. N.;Vazquez, M.;

Apparue dans: Journal of Applied Physics

Date publication: 04.-2011, volume: 109, issue:7, pages: 07A321 - 07A321-3

Editeur: IEEE

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» 1-D Transforms for the Motion Compensation Residual

Résumé:
Transforms used in image coding are also commonly used to compress prediction residuals in video coding. Prediction residuals have different spatial characteristics from images, and it is useful to develop transforms that are adapted to prediction residuals. In this paper, we explore the differences between the characteristics of images and motion compensated prediction residuals by analyzing their local anisotropic characteristics and develop transforms adapted to the local anisotropic characteristics of these residuals. The analysis indicates that many regions of motion compensated prediction residuals have 1-D anisotropic characteristics and we propose to use 1-D directional transforms for these regions. We present experimental results with one example set of such transforms within the H.264/AVC codec and the results indicate that the proposed transforms can improve the compression efficiency of motion compensated prediction residuals over conventional transforms.

Auteurs: Kamisli, F.;Lim, J. S.;

Apparue dans: IEEE Transactions on Image Processing

Date publication: 04.-2011, volume: 20, issue:4, pages: 1036 - 1046

Editeur: IEEE

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» 1-Tbyte/s 1-Gbit DRAM Architecture Using 3-D Interconnect for High-Throughput Computing

Résumé:
Aiming to resolve memory bottlenecks in multi-core system, novel 1-Tbyte/s 1-Gbit DRAM architecture based on a multi-core configuration and 3-D interconnects was developed. The DRAM stacked on a multi-core CPU has 512-bit I/Os with through-silicon-via (TSV) distributed in 16 memory cores. Five-stage pipelined architecture in the compact DRAM core was developed to reduce the operation cycle of the data-bus to 2 ns. A low-noise early-bar-write scheme for an 8-ns cycle array operation and 16-Gbit/s I/O circuits on TSV were also developed. The proposed DRAM architecture greatly improves power efficiency. TSV scheme reduces the parasitic capacitance of the interconnects between the DRAM and CPU, and multi-core architecture reduces the length of the data bus on the DRAM. A 1-Gbit DRAM was designed based on the 45-nm stand-alone DRAM process. Chip size is 51.6 mm² assuming 4F² memory cells, and the density is about 5 times higher than that of embedded DRAM. Circuit simulations confirmed the 2-ns operation of the data bus, 8-ns operation of the memory array, and 16-Gbit/s operation of I/O circuits. Power consumption is 19.5 W, providing power efficiency of 51.3 Gbyte/s/W, which is an order of magnitude higher than that of conventional DRAMs.

Auteurs: Sekiguchi, T.;Ono, K.;Kotabe, A.;Yanagawa, Y.;

Apparue dans: IEEE Journal of Solid-State Circuits

Date publication: 04.-2011, volume: 46, issue:4, pages: 828 - 837

Editeur: IEEE

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» 1.2 nm Capacitance Equivalent Thickness gate stacks on Si-passivated GaAs

Résumé:
Experiments to increase the specific capacitance of MOS capacitors consisting of HfO2 on a passivating interfacial layer (IL) of amorphous Si (a-Si) on GaAs are described. XPS analysis of the layers and electrical measurements on the capacitors are combined to study the evolution of the gate-stack during deposition and subsequent heat treatments. It is shown that oxidation of the a-Si IL is a major factor in preventing the attainment of a scaled capacitance equivalent thickness (CET). By controlling the deposition of the layers, the gate metal and the heat treatments, a highly scaled gate stack with a CET of 1.2nm...

Auteurs: M., El Kazzi , D.J., Webb , L., Czornomaz , C., Rossel , C., Gerl , ...

Apparue dans: Microelectronic Engineering

Date publication: 04.-2011

Editeur: Elsevier B.V.

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» 1/f Baseband Noise Suppression in OFDM Systems

Résumé:
The commonly used direct-conversion Radio Frequency (RF) chips exhibit an additive 1/f baseband noise around the DC. The 1/f noise level increases as the transistors inside the RF chip become ever smaller. This type of noise mainly affects the low frequencies and can be very significant for small frequency allocations around the DC in Orthogonal Frequency-Division Multiple Access (OFDMA) systems. In this article we present the effects of such 1/f baseband noise on small frequency allocations for a Long Term Evolution (LTE) User Equipment (UE). We proceed to estimate the 1/f baseband noise. Suppression of the 1/f baseband noise is achieved by subtracting the estimated 1/f baseband noise from the received signal. We show that considerable processing gain is achieved when the 1/f baseband noise suppression is applied.

Auteurs: Landis, Shay;Bobrovsky, Ben-Zion;

Apparue dans: IEEE Transactions on Communications

Date publication: 04.-2011, volume: 59, issue:4, pages: 942 - 947

Editeur: IEEE

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» 2-D/3-D Switchable Display by Fresnel-Type LC Lens

Résumé:
We demonstrate a multi-electrode Fresnel-type 2-D/3-D switchable display with electrically controlled birefringence mode liquid crystal (LC) lenses. By applying a discontinuous nonuniform electric field, the display with this structure can form a Fresnel-type refractive-index distribution to generate 3-D images. Compared to a normal LC lens, the Fresnel-type LC lens can achieve faster switching speed for dynamic applications. It can also replace the high sag solid lens for 3-D applications with relatively small cell gap. Furthermore, a Fresnel lens with suitable refractive-index profile is proposed to reduce the crosstalk in the 3-D displays.

Auteurs: Lu, J.-G.;Sun, X.-F.;Song, Y.;Shieh, H.-P. D.;

Apparue dans: Journal of Display Technology

Date publication: 04.-2011, volume: 7, issue:4, pages: 215 - 219

Editeur: IEEE

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» 2010 EuroSimE international conference on thermal, mechanical and multi-physics simulation and experiments in micro-electronics and micro-systems

Résumé:
Artur, Wymys?owski

Auteurs: Source: Microelectronics Reliability, In Press, Corrected Proof, Available online 2 April 2011

Apparue dans: Microelectronics Reliability

Date publication: 04.-2011

Editeur: Elsevier B.V.

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» 3-D Video Representation Using Depth Maps

Résumé:
Current 3-D video (3DV) technology is based on stereo systems. These systems use stereo video coding for pictures delivered by two input cameras. Typically, such stereo systems only reproduce these two camera views at the receiver and stereoscopic displays for multiple viewers require wearing special 3-D glasses. On the other hand, emerging autostereoscopic multiview displays emit a large numbers of views to enable 3-D viewing for multiple users without requiring 3-D glasses. For representing a large number of views, a multiview extension of stereo video coding is used, typically requiring a bit rate that is proportional to the number of views. However, since the quality improvement of multiview displays will be governed by an increase of emitted views, a format is needed that allows the generation of arbitrary numbers of views with the transmission bit rate being constant. Such a format is the combination of video signals and associated depth maps. The depth maps provide disparities associated with every sample of the video signal that can be used to render arbitrary numbers of additional views via view synthesis. This paper describes efficient coding methods for video and depth data. For the generation of views, synthesis methods are presented, which mitigate errors from depth estimation and coding.

Auteurs: Muller, K.;Merkle, P.;Wiegand, T.;

Apparue dans: Proceedings of the IEEE

Date publication: 04.-2011, volume: 99, issue:4, pages: 643 - 656

Editeur: IEEE

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» 380 kV corona ring optimization for AC voltages

Résumé:
This paper presents corona ring optimization for 380 kV V-insulator string composed of glass insulator units. The influence of the corona ring design parameters are examined not only with regard to 3D simulations but also laboratory tests. The purpose of the simulations is to find reasonable corona ring design parameters such as corona ring diameter, corona tube diameter and installation height on the point of effective field regulation around the critical region of the string. Indoor laboratory tests including radio interference voltage levels, corona inception voltages and ac flashover voltages are conducted on the centre phase of a full scaled tower both for experimental based corona ring design as well as verifications of the simulations. After both simulations and experimental based investigations, appropriate corona ring design parameters for the string are determined for effective field regulation, minimum interference level, ac flashover performance and economic point of view.

Auteurs: Ilhan, S.;Ozdemir, A.;

Apparue dans: IEEE Transactions on Dielectrics and Electrical Insulation

Date publication: 04.-2011, volume: 18, issue:2, pages: 408 - 417

Editeur: IEEE

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» 3D analytical solution for a functionally graded transversely isotropic piezoelectric circular plate under tension and bending

Résumé:
A three-dimensional (3D) analysis of a functionally graded piezoelectric circular plate under tension and bending is carried out. A direct displacement method is developed, with analytical solutions obtained for plate with either free or simply-supported edge conditions. The material properties of the plate can vary arbitrarily along the thickness except that the strain-energy function should be positive definite as required for stable materials and certain integrable conditions are assumed valid during the derivation. The validity of the present solutions is discussed both analytically and numerically. Numerical analyses are made for a specific functionally graded material to show the influence of...

Auteurs: X.Y., Li , J., Wu , H.J., Ding , W.Q., Chen

Apparue dans: International Journal of Engineering Science

Date publication: 04.-2011

Editeur: Elsevier B.V.

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» 3D Floorplanning of Low-Power and Area-Efficient Network-on-Chip Architecture

Résumé:
Network-on-Chip (NoC) architectures have been adopted by chip multiprocessors (CMPs) as a flexible solution to the increasing delay in the deep sub-micron regime. However, the shrinking feature size limits the performance of NoCs due to power and area constraints. In this paper, we propose three 3D floorplanning methods for a Triplet-based Hierarchical Interconnection Network (THIN) which is a new high performance NoC. The proposed floorplanning methods use both Manhattan and Y-architecture routing architectures so as to improve the performance, reduce the power consumption and area requirement of THIN. A cycle accurate simulator was developed based on Noxim NoC simulator and...

Auteurs: Licheng, Xue , Feng, Shi , Weixing, Ji , Haroon-Ur-Rashid, Khan

Apparue dans: Microprocessors and Microsystems

Date publication: 04.-2011

Editeur: Elsevier B.V.

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» 3D Human Posture Segmentation by Spectral Clustering with Surface Normal constraint

Résumé:
In this paper, we propose a new algorithm for partitioning human posture represented by 3D point clouds sampled from the surface of human body. The algorithm is formed as a constrained extension of the recently developed segmentation method, spectral clustering (SC). Two folds of merits are offered by the algorithm: 1) as a nonlinear method, it is able to deal with the situation that data (point cloud) are sampled from a manifold (the surface of human body) rather than the embedded entire 3D space; 2) by using constraints, it facilitates the integration of multiple similarities for human posture partitioning, and...

Auteurs: Jun, Cheng , Maoying, Qiao , Wei, Bian , Dacheng, Tao

Apparue dans: Signal Processing

Date publication: 04.-2011

Editeur: Elsevier B.V.

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» 3D Images Using CSpace Display for Air Traffic Control Applications

Résumé:
We explore here the capabilities and performance issues encountered when using a novel static volume display, CSpace, for realizing moving images required to deliver real time three-dimensional (3D) visualization and manipulation for Air Traffic Controllers (ATC). The display uses a {\{19 mm}}\times {\{18 mm}}\times {\{100 mm}} 2% Erbium-doped sodium–ytterbium–fluoride (NYF) crystal as the image space, and a pair of digital micromirror devices (DMD) to address and render successive slices of the image within the crystal. Display-specific software and digital light processing (DLP) boards provide image data to and control the DMD devices respectively. The ability to render and display moving images quickly enough for applications such as air-traffic control is strongly dependent on several factors, including the speed of the software and hardware components. 3D images of aircraft in the sky and terrain were captured to explore how well the display performed as the time between successive images in a short motion sequence was systematically reduced, and to examine the key factors that control the performance of the display in presenting these images.

Auteurs: Refai, H. H.;

Apparue dans: Journal of Display Technology

Date publication: 04.-2011, volume: 7, issue:4, pages: 186 - 192

Editeur: IEEE

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» 3D Power Synthesis with Reduction of Near-Field and Dynamic Range Ratio for Conformal Antenna Arrays

Résumé:
A simple method of power synthesis for 3D radiation patterns of conformal antenna arrays is presented. The method enables to synthesize a desired far-field pattern simultaneously controlling the dynamic range ratio (DRR) of the array excitations and the electric field amplitude in a given region of interest close to the antenna. The power synthesis problem is reduced to a field synthesis one by introducing an auxiliary phase pattern, which is incorporated in a cost function together with the desired far-field pattern, the array pattern, the near electric field amplitude, and the array excitations. Such cost function is minimized by iteratively modifying the auxiliary phase pattern and the array excitations. Applications of the proposed method to conformal arrays of different geometries show that accurate results are obtained also in presence of stringent requirements and within acceptable CPU times, even when hundreds of elements are involved.

Auteurs: Comisso, M.;Vescovo, R.;

Apparue dans: IEEE Transactions on Antennas and Propagation

Date publication: 04.-2011, volume: 59, issue:4, pages: 1164 - 1174

Editeur: IEEE

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» 3D-Aggregate Quantitative Imaging: Experimental Results and Polarization Effects

Résumé:
We present reconstructions of an aggregate of small spheres from experimental scattered fields using a working frequency of 18 GHz. This target presents at the same time a complex 3D shape and a low-contrast permittivity. Concerted experimental and numerical efforts have enabled to obtain accurate reconstructions. In particular, we took into account the real random noise via a Bayesian framework. Reconstructions have been realized with scattered fields measured in different polarization cases: the results are compared and discussed.

Auteurs: Eyraud, C.;Geffrin, J.-M.;Litman, A.;

Apparue dans: IEEE Transactions on Antennas and Propagation

Date publication: 04.-2011, volume: 59, issue:4, pages: 1237 - 1244

Editeur: IEEE

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» 3D-Interconnect: Visualization of Extrusion and Voids Induced in Copper-Filled Through-Silicon Vias (TSVs) at Various Temperatures Using X-ray Microscopy

Résumé:

Auteurs: Visualization of voids and copper extrusion in copper-filled through-silicon vias (TSVs) under different annealing conditions is greatly enhanced using X-ray microscopy. In addition, the dimensions of the TSVs after Cu deposition can also be measured

Apparue dans: Microelectronic Engineering

Date publication: 04.-2011

Editeur: Elsevier B.V.

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» 53 Gbps Native {\rm GF}(2 ^{4}) ^{2} Composite-Field AES-Encrypt/Decrypt Accelerator for Content-Protection in 45 nm High-Performance Microprocessors

Résumé:
Abstract-This paper describes an on-die, reconfigurable AES encrypt/decrypt hardware accelerator fabricated in 45 nm CMOS, targeted for content-protection in high-performance microprocessors. 100% round computation in native GF(2⁴)² composite-field arithmetic, unified reconfigurable datapath for encrypt/decrypt, optimized ground & composite-field polynomials, integrated affine/bypass multiplexer circuits, fused Mix/InvMixColumn circuits and a folded ShiftRow datapath enable peak 2.2 Tbps/Watt AES-128 energy efficiency with a dense 2-round layout occupying 0.052 mm², while achieving: (i) 53/44/38 Gbps AES-128/192/256 performance, 125 mW, measured at 1.1 V, 50 °C, (ii) scalable AES-128 performance up to 66 Gbps, measured at 1.35 V, 50 °C, (iii) wide operating supply voltage range with robust subthreshold voltage performance of 800 Mbps, 409 μW, measured at 320 mV, 50 °C (iv) 37% Sbox delay reduction and 25% area reduction with a compact Sbox layout occupying 759 μm² (v) 67% reduction in worst-case interconnect length and 33% reduction in ShiftRow wiring tracks and (vi) 43 % reduction in Mix/InvMixColumn area with no performance penalty.

Auteurs: Mathew, S.K.;Sheikh, F.;Kounavis, M.;Gueron, S.;Agarwal, A.;Hsu, S.K.;Kaul, H.;Anders, M.A.;Krishnamurthy, R.K.;

Apparue dans: IEEE Journal of Solid-State Circuits

Date publication: 04.-2011, volume: 46, issue:4, pages: 767 - 776

Editeur: IEEE

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» 600-fs Mode-Locked Tm–Ho-Doped Fiber Laser Synchronized to Optical Clock With Optically Driven Semiconductor Saturable Absorber

Résumé:
Using amplitude modulation in a semiconductor saturable absorber mirror induced by optical clock signal, we have synchronized 600-fs pulse train from a mode-locked thulium–holmium fiber laser operating at 1.99 \\mu{m} to an external reference source. The optical source based on 1.56-\\mu{m} distributed-feedback diode laser driven by the clock signal was used as a seed source. The amplified seed pulses launched into the fiber cavity synchronized the mode-locked pulses through amplitude modulation in the absorber. The synchronization method allows us to operate the mode-locked laser at multiples of cavity harmonics and to increase the repetition rate.Pub _bookmark Command="[Quick Mark]"

Auteurs: Kivisto, S.;Okhotnikov, O. G.;

Apparue dans: IEEE Photonics Technology Letters

Date publication: 04.-2011, volume: 23, issue:8, pages: 477 - 479

Editeur: IEEE

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» H_{\infty } Filtering For Nonlinear Discrete-Time Systems Subject to Quantization and Packet Dropouts

Résumé:
This paper investigates the problem of H_{infty } filtering for a class of nonlinear discrete-time systems with measurement quantization and packet dropouts. Each output is transmitted via an independent communication channel, and the phenomenon of packet dropouts in transmission is governed by an individual random binary distribution, while the quantization errors are treated as sector-bound uncertainties. Based on a piecewise-Lyapunov function, an approach to the design of H_{infty }-piecewise filter is proposed such that the filtering-error system is stochastically stable with a guaranteed H_{infty }$ performance. Some slack matrices are introduced to facilitate the filter design procedure by eliminating the coupling between the Lyapunov matrices and the system matrices. The filter parameters can be obtained by solving a set of linear-matrix inequalities (LMIs), which are numerically tractable with commercially available software. Finally, two illustrative examples are provided to show the effectiveness of the proposed method.

Auteurs: Zhang, C.;Feng, G.;Gao , H.;Qiu, J.;

Apparue dans: IEEE Transactions on Fuzzy Systems

Date publication: 04.-2011, volume: 19, issue:2, pages: 353 - 365

Editeur: IEEE

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» H_{\infty } Filtering For Nonlinear Discrete-Time Systems Subject to Quantization and Packet Dropouts

Résumé:
This paper investigates the problem of H_∞ filtering for a class of nonlinear discrete-time systems with measurement quantization and packet dropouts. Each output is transmitted via an independent communication channel, and the phenomenon of packet dropouts in transmission is governed by an individual random binary distribution, while the quantization errors are treated as sector-bound uncertainties. Based on a piecewise-Lyapunov function, an approach to the design of H_∞-piecewise filter is pro posed such that the filtering-error system is stochastically stable with a guaranteed H_∞ performance. Some slack matrices are introduced to facilitate the filter design procedure by eliminating the coupling between the Lyapunov matrices and the system matrices. The filter parameters can be obtained by solving a set of linear matrix inequalities (LMIs), which are numerically tractable with commercially available software. Finally, two illustrative examples are provided to show the effectiveness of the proposed method.

Auteurs: Changzhu Zhang;Gang Feng;Huijun Gao;Jianbin Qiu;

Apparue dans: IEEE Transactions on Fuzzy Systems

Date publication: 04.-2011, volume: 19, issue:2, pages: 353 - 365

Editeur: IEEE

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» \ {HfO}_{x}/\ {TiO}_{x}/\ {HfO}_{x}/ \ {TiO}_{x} Multilayer-Based Forming-Free RRAM Devices With Excellent Uniformity

Résumé:
In this letter, a significantly improved uniformity of device parameters (for cycle-to-cycle uniformity within one device and device-to-device uniformity), such as set voltage, reset voltage, and HRS and LRS resistance distributions, is successfully demonstrated on HfO_x/TiO_x multilayer (ML)-based resistive switching devices, as compared with HfO_x-based single-layer device. In addition, the reported ML devices are free from forming process, which is greatly beneficial from the viewpoint of RRAM circuit operation. It is believed that both the Ti doping effect and the confinement of conduction filament within different dielectrics layers contribute to the improvement.

Auteurs: Fang, Z.;Yu, H.Y.;Li, X.;Singh, N.;Lo, G.Q.;Kwong, D.L.;

Apparue dans: IEEE Electron Device Letters

Date publication: 04.-2011, volume: 32, issue:4, pages: 566 - 568

Editeur: IEEE

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» k-Fold Cyclotomy and Its Application to Frequency-Hopping Sequences

Résumé:
For an integer kgeq 1, let q_{i}, \\sim 1leq ileq k, be prime powers such that q_{i}=M_{i}f+1 for some integers M_{i} and f. In this paper, the k-fold cyclotomy of BBF_{q_{1}}\times cdots \times BBF_{q_{k}} as a nontrivial generalization of the conventional cyclotomy (k=1 case) and its application to frequency-hopping sequences (FHSs) are presented, where BBF_{q} is the finite field with q elements. First, the definitions of k-fold cyclotomic classes and k-fold cyclotomic numbers are given. And then, their basic properties including k-fold diagonal sums are derived. Based on them, new optimal FHS sets of length N and frequency set size M or M+1 with respect to the Peng-Fan bound are constructed for a product N of distinct odd primes and a divisor M of <- - formula formulatype="inline">$N-1$ . Furthermore, new optimal FHSs of length N and frequency set size M with respect to the Lempel–Greenberger bound are constructed when N has at least one prime factor which is 3 modulo 4 and (N-1)/M is an even integer. Our constructions give several new optimal parameters not covered in the literature, which are summarized in Table I .

Auteurs: Chung, J.-H.;Yang, K.;

Apparue dans: IEEE Transactions on Information Theory

Date publication: 04.-2011, volume: 57, issue:4, pages: 2306 - 2317

Editeur: IEEE

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» \{HfO}_{x}/\{TiO}_{x}/\{HfO}_{x}/ \{TiO}_{x} Multilayer-Based Forming-Free RRAM Devices With Excellent Uniformity

Résumé:
In this letter, a significantly improved uniformity of device parameters (for cycle-to-cycle uniformity within one device and device-to-device uniformity), such as set voltage, reset voltage, and HRS and LRS resistance distributions, is successfully demonstrated on \{HfO}_{x}/\{TiO}_{x}$ multilayer (ML)-based resistive switching devices, as compared with \{HfO}_{x}-based single-layer device. In addition, the reported ML devices are free from forming process, which is greatly beneficial from the viewpoint of RRAM circuit operation. It is believed that both the Ti doping effect and the confinement of conduction filament within different dielectrics layers contribute to the improvement.

Auteurs: Fang, Z.;Yu, H. Y.;Li, X.;Singh, N.;Lo, G. Q.;Kwong, D. L.;

Apparue dans: IEEE Electron Device Letters

Date publication: 04.-2011, volume: 32, issue:4, pages: 566 - 568

Editeur: IEEE

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» ¹¹⁹Sn Mössbauer spectroscopy study of UCo1-xRuxSn solid solutions

Résumé:
The influence of the substitution of Co for Ru on the magnetic hyperfine fields Bhf on ¹¹⁹Sn nuclei in UCo1-xRuxSn solid solutions was investigated. The compounds were crystallized in a hexagonal crystal structure of the ZrNiAl type. This structure is characterized by two nonequivalent crystal positions of d-metal. It was shown that Bhf measured at 5 K decreases with an increase in Ru content. Such a dependence of Bhf is opposite to the concentration dependence of the uranium magnetic moments. Therefore, the different mechanisms and electron groups are responsible for the formation of the U magnetic moments and the hyperfine magnetic field on the ¹¹⁹Sn nuclei. It has been concluded from analysis of the obtained results that (i) the observed linear reduction of electron polarization on ¹¹⁹Sn nuclei can be explained by the decrease in density of the s-electrons due to the hybridization of the s-electrons of Sn with Ru/Co atoms, and (ii) the Ru/Co atoms in the two crystal positions make significantly different contributions not just to the 5f-d hybridized band but also to the formation of the magnetic hyperfine fields on ¹¹⁹Sn nuclei.

Auteurs: Krylov, V. I.;

Apparue dans: Journal of Applied Physics

Date publication: 04.-2011, volume: 109, issue:7, pages: 07E140 - 07E140-3

Editeur: IEEE

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» A 0.4dB noise figure wideband low-noise amplifier using a novel InGaAs/InAlAs/InP device

Résumé:
In this work, the design of a novel low-noise amplifier (LNA) based on 1?m gate-length InGaAs/InAlAs/InP pHEMT transistors is discussed. Designed for radioastronomy applications, this amplifier exploits a common-drain configuration as input stage and a common-source inductive degeneration topology as output stage. It exhibits a maximum gain of 30dB within an input 1dB compression point of -16dBm. The noise figure is 0.4dB with an input return loss greater than -10dB and an output return loss of -12.5dB. The LNA consumes 85mW from a 1.5V power supply.

Auteurs: Z., Hamaizia , N., Sengouga , M., Missous , M.C.E., Yagoub

Apparue dans: Materials Science in Semiconductor Processing

Date publication: 04.-2011

Editeur: Elsevier B.V.

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» A 0.55 V 10 fJ/bit Inductive-Coupling Data Link and 0.7 V 135 fJ/Cycle Clock Link With Dual-Coil Transmission Scheme

Résumé:
This paper presents a 10 fJ/bit inductive-coupling data link operating at 0.55 V supply voltage and a 135 fJ/cycle clock link at 0.7 V supply voltage. A dual-coil transmission scheme reduces the number of stacked transistors in a transmitter, enabling low-voltage and hence low-power operation. A test chip is fabricated in 65 nm CMOS whose nominal supply voltage is 1.2 V. A data rate of 1.1 Gb/s and a clock rate of 3.3 GHz, both with an error rate <; 10^-12, are achieved at 0.55 V and 0.7 V supply voltage, respectively.

Auteurs: Miura, N.;Shidei, T.;Yuan, Y.;Kawai, S.;Takatsu, K.;Kiyota, Y.;Asano, Y.;Kuroda, T.;

Apparue dans: IEEE Journal of Solid-State Circuits

Date publication: 04.-2011, volume: 46, issue:4, pages: 965 - 973

Editeur: IEEE

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» A 1-V 4-GHz wide tuning range voltage-controlled ring oscillator in 0.18?m CMOS

Résumé:
A new differential delay cell with complementary current control to extend the control voltage range as well as the operation frequency is proposed for low voltage and wide tuning range voltage-controlled ring oscillator (VCRO). The complementary current control can get rid of the restriction that control voltage is unable to cover the full range of power supply voltage in a conventional VCRO. A three-stage VCRO chip working with 1V power supply voltage is constructed using 0.18?m 1P6M CMOS process for verifying the efficacy of the proposed differential delay cell. Measured results of the VCRO chip show that a wide range...

Auteurs: Meng-Lieh, Sheu , Yu-Shang, Tiao , Lin-Jie, Taso

Apparue dans: Microelectronics Journal

Date publication: 04.-2011

Editeur: Elsevier B.V.

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» A 1-V, 16.9 ppm/^{\\circ}C, 250 nA Switched-Capacitor CMOS Voltage Reference

Résumé:
An ultra low-power, precise voltage reference using a switched-capacitor technique in 0.35-\mum CMOS is presented in this paper. The temperature dependence of the carrier mobility and channel length modulation effect can be effectively minimized by using 3.3 and 5 V N-type transistors to operate in the saturation and subthreshold regions, respectively. In place of resistors, a precise reference voltage with flexible trimming capability is achieved by using capacitors. When the supply voltage is 1 V and the temperature is 80 ^{\circ}C, the supply current is 250 nA. The line sensitivity is 0.76%/V; the PSRR is - 41 dB at 100 Hz and - 17 dB at 10 MHz. Moreover, the occupied die area is 0.049 mm^{2}.

Auteurs: Hsieh, C.-Y.;Huang, H.-W.;Chen, K.-H.;

Apparue dans: IEEE Transactions on Very Large Scale Integration Systems

Date publication: 04.-2011, volume: 19, issue:4, pages: 659 - 667

Editeur: IEEE

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» A 1-V, 16.9 ppm/^{\\circ}C, 250 nA Switched-Capacitor CMOS Voltage Reference

Auteurs: Hsieh, C.-Y.;Huang, H.-W.;Chen, K.-H.;

Apparue dans: IEEE Transactions on Very Large Scale Integration Systems

Date publication: 04.-2011, volume: 19, issue:4, pages: 659 - 667

Editeur: IEEE

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» A 1-V, 16.9 ppm/^{\\circ}C, 250 nA Switched-Capacitor CMOS Voltage Reference

Auteurs: Hsieh, C.-Y.;Huang, H.-W.;Chen, K.-H.;

Apparue dans: IEEE Transactions on Very Large Scale Integration Systems

Date publication: 04.-2011, volume: 19, issue:4, pages: 659 - 667

Editeur: IEEE

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» A 1-V, 16.9 ppm/^{\\circ}C, 250 nA Switched-Capacitor CMOS Voltage Reference

Auteurs: Hsieh, C.-Y.;Huang, H.-W.;Chen, K.-H.;

Apparue dans: IEEE Transactions on Very Large Scale Integration Systems

Date publication: 04.-2011, volume: 19, issue:4, pages: 659 - 667

Editeur: IEEE

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» A 1-V, 16.9 ppm/^{\\circ}C, 250 nA Switched-Capacitor CMOS Voltage Reference

Auteurs: Hsieh, C.-Y.;Huang, H.-W.;Chen, K.-H.;

Apparue dans: IEEE Transactions on Very Large Scale Integration Systems

Date publication: 04.-2011, volume: 19, issue:4, pages: 659 - 667

Editeur: IEEE

Document complet vers site de l'éditeur

» A 1-V, 16.9 ppm/^{\\circ}C, 250 nA Switched-Capacitor CMOS Voltage Reference

Résumé:
An ultra low-power, precise voltage reference using a switched-capacitor technique in 0.35-μm CMOS is presented in this paper. The temperature dependence of the carrier mobility and channel length modulation effect can be effectively minimized by using 3.3 and 5 V N-type transistors to operate in the saturation and subthreshold regions, respectively. In place of resistors, a precise reference voltage with flexible trimming capability is achieved by using capacitors. When the supply voltage is 1 V and the temperature is 80°C, the supply current is 250 nA. The line sensitivity is 0.76%/V; the PSRR is -41 dB at 100 Hz and -17 dB at 10 MHz. Moreover, the occupied die area is 0.049 mm².

Auteurs: Chun-Yu Hsieh;Hong-Wei Huang;Ke-Horng Chen;

Apparue dans: IEEE Transactions on Very Large Scale Integration Systems

Date publication: 04.-2011, volume: 19, issue:4, pages: 659 - 667

Editeur: IEEE

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» A 1.2–1.6-GHz Substrate-Integrated-Waveguide RF MEMS Tunable Filter

Résumé:
This paper presents a high-performance substrate-integrated-waveguide RF microelectromechanical systems (MEMS) tunable filter for 1.2–1.6-GHz frequency range. The proposed filter is developed using packaged RF MEMS switches and utilizes a two-layer structure that effectively isolates the cavity filter from the RF MEMS switch circuitry. The two-pole filter implemented on RT/Duroid 6010LM exhibits an insertion loss of 2.2–4.1 dB and a return loss better than 15 dB for all tuning states. The relative bandwidth of the filter is 3.7 pm 0.5% over the tuning range. The measured Q_{u} of the filter is 93–132 over the tuning range, which is the best reported Q in filters using off-the-shelf RF MEMS switches on conventional printed circuit board substrates. In addition, an upper stopband rejection better than 28 dB is obtained up to 4.0 GHz by employing low-pass filters at the bandpass filter terminals at the cost of 0.7–1.0-dB increase in the insertion loss.

Auteurs: Sekar, V.;Armendariz, M.;Entesari, K.;

Apparue dans: IEEE Transactions on Microwave Theory and Techniques

Date publication: 04.-2011, volume: 59, issue:4, pages: 866 - 876

Editeur: IEEE

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» A 112 Mb/s Full Duplex Remotely-Powered Impulse-UWB RFID Transceiver for Wireless NV-Memory Applications

Résumé:
A dual band symmetrical UWB-RFID transceiver for high capacity wireless NV-Memory applications is reported. The circuit exhibits a figure of merit of 58 pJ/b and 48 pJ/b in Tx and Rx respectively, with a 112.5 Mb/s data rate capability. It operates in the 7.9 GHz UWB frequency band for full duplex communication and is remotely powered through a UHF CW signal. The circuit has been implemented in a 0.13 μm 1.2 V CMOS process.

Auteurs: Pelissier, M.;Jantunen, J.;Gomez, B.;Arponen, J.;Masson, G.;Dia, S.;Varteva, J.;Gary, M.;

Apparue dans: IEEE Journal of Solid-State Circuits

Date publication: 04.-2011, volume: 46, issue:4, pages: 916 - 927

Editeur: IEEE

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» A 12-GS/s 81-mW 5-bit Time-Interleaved Flash ADC With Background Timing Skew Calibration

Résumé:
This paper presents a 12-GS/s 5-bit time-interleaved flash ADC realized in 65-nm CMOS. To improve the dynamic performance at high input frequencies, a statistics-based background calibration scheme for timing skew is employed. The timing skew is detected in the digital domain through a correlation-based algorithm and minimized by adjusting digitally controlled delay lines. In order to minimize power consumption, we employ near minimum size comparators, whose offset is reduced through foreground calibrated trim-DAC circuitry. With the timing calibration activated, the skew-related impairments are reduced by 12 dB at high input frequencies, resulting in an SNDR of 25.1 dB near Nyquist. The prototype IC consumes 81 mW from a 1.1 V supply, yielding a figure-of-merit of 0.35 pJ/conversion-step at low input frequencies, and 0.46 pJ/conversion-step for inputs near Nyquist.

Auteurs: El-Chammas, M.;Murmann, B.;

Apparue dans: IEEE Journal of Solid-State Circuits

Date publication: 04.-2011, volume: 46, issue:4, pages: 838 - 847

Editeur: IEEE

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» A 2 Tb/s 6,\\times,4 Mesh Network for a Single-Chip Cloud Computer With DVFS in 45 nm CMOS

Résumé:
A packet-switched 6 × 4 2-D mesh network providing 2 Tb/s of bisectional bandwidth with a per-hop latency of 4-cycles, forms the high performance communication fabric for a Single-Chip Cloud Computer (SCC) with 48 Pentium™ class IA-32 cores. The fabric operates on an independent power supply and frequency domain. The router micro-architecture achieves over 90% network utilization by effective use of a single-cycle Wrapped Wave-Front Allocator (WWFA) and virtual channel (VC) flow control. A router transit latency of 2 ns is achieved through early buffer write, route pre-computation and a single-cycle WWFA implementation. This 640 K transistor, 1.32 mm² router operates at 2 GHz at 1.1 V while dissipating 550 mW. The 24-node mesh network with 1.28 Tb/s router and 16B, 5.4 mm wide links consumes only 5% of the chip area, 1.2% of the transistors and 10% of total chip power at 1.1 V in a 45 nm nine-metal CMOS process. The router energy efficiency scales from 1.3 Tb/s/W to 7.2 Tb/s/W over a dynamic voltage range from 0.7 V to 1.25 V.

Auteurs: Salihundam, P.;Jain, S.;Jacob, T.;Kumar, S.;Erraguntla, V.;Hoskote, Y.;Vangal, S.;Ruhl, G.;Borkar, N.;

Apparue dans: IEEE Journal of Solid-State Circuits

Date publication: 04.-2011, volume: 46, issue:4, pages: 757 - 766

Editeur: IEEE

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» A 21.5kHz High Optical Resolution Electrostatic Double-layered Vibratory Grating Laser Scanner

Résumé:
This paper presents a 21.5kHz high optical resolution electrostatic double-layered vibratory grating laser scanner with an improved grating platform. Detailed optical characterizations of the prototype scanner is measured and reported. The scanner is capable of scanning a laser beam at about 21.5kHz. The optical resolution of the prototype scanner is measured to be 916 pixels per-unidirectional-scan while scanning in atmosphere. While scanning in vacuum condition, the optical resolution can be estimated to be 1460 pixels per-unidirectional-scan, which is suitable for SXGA (1280×1024) resolution scanned beam displays.

Auteurs: Yu, Du , Guangya, Zhou , Kelvin K.L., Cheo , Qingxin, Zhang , Hanhua, Feng , ...

Apparue dans: Sensors and Actuators A: Physical

Date publication: 04.-2011

Editeur: Elsevier B.V.

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» A 250 mV, 352 \\muW GPS Receiver RF Front-End in 130 nm CMOS

Résumé:
A fully integrated CMOS GPS receiver RF front-end is presented. Systematic circuit optimizations for ultra-low voltage operation including subthreshold biasing, a novel mixer-VCO interface, and charge neutralization enable the supply voltage to be dramatically reduced as a means to save power. The 250 mV supply is the lowest ever reported for any integrated receiver RF front-end to date. Its 352 μW power consumption represents a three times power savings compared to the prior lowest GPS receiver RF front-ends reported in the literature. The prototype was fabricated in a 1P8M 130 nm CMOS process and includes a variable gain LNA, a quadrature VCO, quadrature mixers, and all required bias circuitry. The system has a measured gain of 42 dB, a noise figure of 7.2 dB, and an oscillator phase noise of - 112.4 dBc/Hz at a 1 MHz offset, resulting in a VCO FoM of 187.4 dBc/Hz.

Auteurs: Heiberg, A.C.;Brown, T.W.;Fiez, T.S.;Mayaram, K.;

Apparue dans: IEEE Journal of Solid-State Circuits

Date publication: 04.-2011, volume: 46, issue:4, pages: 938 - 949

Editeur: IEEE

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» A 3-DOF Parallel Robot With Spherical Motion for the Rehabilitation and Evaluation of Balance Performance

Résumé:
In this paper a novel electrically actuated parallel robot with three degrees-of-freedom (3 DOF) for dynamic postural studies is presented. The design has been described, the solution to the inverse kinematics has been found, and a numerical solution for the direct kinematics has been proposed. The workspace of the implemented robot is characterized by an angular range of motion of about {pm}10^{\circ} for roll and pitch when yaw is in the range {pm}15^{\circ}. The robot was constructed and the orientation accuracy was tested by means of an optoelectronic system and by imposing a sinusoidal input, with a frequency of 1 Hz and amplitude of 10^{\circ}, along the three axes, in sequence. The collected data indicated a phase delay of 1^{\circ} and an amplitude error of 0.5%–1.5%; similar values were observed for cross-axis sensitivity errors. We also conducted a clinical application on a group of normal subjects, who were standing in equilibrium on the robot base with eyes open (EO) and eyes closed (EC), which was rotated with a tri-axial sinusoidal trajectory with a frequency of 0.5 Hz and amplitude 5^{\circ} for roll and pitch and 10^{\circ} for the yaw. The postural configuration of the subjects was recorded with an optoelectronic system. However, due to the mainly technical nature of this paper, only initial validation outcomes are reported here. The clinical application showed that only the tilt and displacement on the sagittal pane of head, trunk, and pelvis in the trials conducted with eyes closed were affected by drift and that the reduction of the - - yaw rotation and of the mediolateral translation was not a controlled parameter, as happened, instead, for the other anatomical directions.

Auteurs: Patane, F.;Cappa, P.;

Apparue dans: IEEE Transactions on Neural Systems and Rehabilitation Engineering

Date publication: 04.-2011, volume: 19, issue:2, pages: 157 - 166

Editeur: IEEE

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» A 300-GHz Fundamental Oscillator in 65-nm CMOS Technology

Résumé:
Fundamental oscillators prove the existence of gain at high frequencies, revealing the speed limitations of other circuits in a given technology. This paper presents an oscillator topology that employs feedback from an output stage to the core, thus achieving a high speed. The behavior of the proposed oscillator is formulated and simulations are used to compare it with the conventional cross-coupled pair circuit. Three prototypes realized in 65-nm CMOS technology operate at 205 GHz, 240 GHz, and 300 GHz, each drawing 3.7 mW from a 0.8-V supply.

Auteurs: Razavi, B.;

Apparue dans: IEEE Journal of Solid-State Circuits

Date publication: 04.-2011, volume: 46, issue:4, pages: 894 - 903

Editeur: IEEE

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» A 32,\\times,32 Pixel Convolution Processor Chip for Address Event Vision Sensors With 155 ns Event Latency and 20 Meps Throughput

Résumé:
This paper describes a convolution chip for event-driven vision sensing and processing systems. As opposed to conventional frame-constraint vision systems, in event-driven vision there is no need for frames. In frame-free event-based vision, information is represented by a continuous flow of self-timed asynchronous events. Such events can be processed on the fly by event-based convolution chips, providing at their output a continuous event flow representing the 2-D filtered version of the input flow. In this paper we present a 32,\times,32 pixel 2-D convolution event processor whose kernel can have arbitrary shape and size up to 32,\times,32. Arrays of such chips can be assembled to process larger pixel arrays. Event latency between input and output event flows can be as low as 155 ns. Input event throughput can reach 20 Meps (mega events per second), and output peak event rate can reach 45 Meps. The chip can be configured to discriminate between two simulated propeller-like shapes rotating simultaneously in the field of view at a speed as high as 9400 rps (revolutions per second). Achieving this with a frame-constraint system would require a sensing and processing capability of about 100 K frames per second. The prototype chip has been built in 0.35 \mu \{m} CMOS technology, occupies 4.3,\times,5.4 \{mm}^{2} and consumes a peak power of 200 mW at maximum kernel size at maximum input event rate.

Auteurs: Camunas-Mesa, L.;Acosta-Jimenez, A.;Zamarreno-Ramos, C.;Serrano-Gotarredona, T.;Linares-Barranco, B.;

Apparue dans: IEEE Transactions on Circuits and Systems I: Regular Papers

Date publication: 04.-2011, volume: 58, issue:4, pages: 777 - 790

Editeur: IEEE

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» A 4-Element Balanced Retrodirective Array for Direct Conversion Transmitter

Résumé:
A phase conjugated array capable of sending two individually modulated signals towards the direction of an interrogator is proposed. Each of the array elements is a dual-fed patch with one input port connected to a 90^{\circ} phase shifting element and a resistive field effect transistor (FET) mixer and the other port just the mixer alone, making the array a balanced structure. A 4-element working prototype was designed at the center frequency of 5.8 GHz. A linearly polarized retrodirectivity has been experimentally confirmed by measuring bi-static radiation patterns with the interrogating signal coming at 0^{\circ}, +30^{\circ}, +60^{\circ}, -15^{\circ}, and -45^{\circ}. A 8.6-dB peak power variation of re-radiation within pm 60^{\circ} normal to plane of the array has been shown in the measured mono-static radiation patterns. To test the ability of direct conversion, an active integrated direct conversion receiver employing the same array has been designed to receive and demodulate the response signals from the phase conjugated array. A 5 MHz square and 8 MHz sinusoidal waves as two base-band signals were carried through the phase conjugated array and successfully recovered by the direct conversion receiver.

Auteurs: Chiu, L.;Xue, Q.;Chan, C. H.;

Apparue dans: IEEE Transactions on Antennas and Propagation

Date publication: 04.-2011, volume: 59, issue:4, pages: 1185 - 1190

Editeur: IEEE

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» A 40-Stage Synchronous Distributed Energy Railgun

Résumé:
The development process pertaining to the design, fabrication, and testing of a 40-stage free-running arc synchronous distributed energy railgun is presented. Research efforts are still ongoing to suppress the restrike phenomenon that is responsible for causing a velocity ceiling around 6 km/s to exist on plasma armature breech-fed railguns. Numerous solutions have been theorized as viable methods of restrike prevention but lack experimental verification. In collaboration on an AFOSR Multidisciplinary University Research Initiative project, the team at Texas Tech University is responsible for characterizing a functional scale model of a synchronous distributed energy railgun to investigate the effectiveness of a distributed energy scheme to suppress the plasma restrike phenomenon and increase plasma armature railgun performance. The distributed energy scheme is theorized to suppress restrike arc formation because the back-EMF voltage is localized to active stage regions. Synchronous operation refers to the speed of an electromagnetic wave in the LC transmission line formed by the rails and capacitors being matched to the velocity of the armature. The railgun drives a hypervelocity (8 km/s) plasma armature, with no payload, to emulate the conditions of a high-altitude microsatellite launch while relieving the financial burden of a large stored energy facility. Experimental data collected from a seven-stage prototype distributed energy system are discussed which will mimic the design and operation of the first seven stages associated with the final 40-stage system, which is currently under construction. The data collected from this prototype as well as the final 40-stage system will be analyzed for secondary arc formation in an attempt to verify the distributed energy scheme's success in suppressing restrike formation.

Auteurs: Karhi, R. W.;Wetz, D. A.;Giesselmann, M.;Mankowski, J. J.;Diehl, J. P.;Kelly, P. M.;

Apparue dans: IEEE Transactions on Plasma Science

Date publication: 04.-2011, volume: 39, issue:4, pages: 1192 - 1197

Editeur: IEEE

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» A 5 Gb/s Link With Matched Source Synchronous and Common-Mode Clocking Techniques

Résumé:
A 5 Gb/s source-synchronous signaling system was developed utilizing a new clock/data skew minimization technique. The method incorporates a transmit clock delay line and integrating receiver yielding an increased tolerance to high frequency transmit source jitter. The system has the potential to support rapid turn-on without the clock buffer latency of conventional source-synchronous systems. A second method to minimize clock distribution delays with embedded clocking via superposition of clock in the common-mode across two differential pairs was also explored. A test device was fabricated in TSMC's 40 nm LP CMOS process and performance measurements indicate substantial margin improvements, even when the matched source-synchronous system is subjected to realistic source SJ and independent PSIJ noise. Comparable performance was also achieved with embedded common-mode clocking with matched peak swings, indicating it as a potential solution for pin-constrained designs.

Auteurs: Zerbe, J.;Daly, B.;Lei Luo;Stonecypher, W.;Dettloff, W.;Eble, J.C.;Stone, T.;Jihong Ren;Leibowitz, B.;Bucher, M.;Satarzadeh, P.;Qi Lin;Yue Lu;Kollipara, R.;

Apparue dans: IEEE Journal of Solid-State Circuits

Date publication: 04.-2011, volume: 46, issue:4, pages: 974 - 985

Editeur: IEEE

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» A 530 Mpixels/s 4096x2160@60fps H.264/AVC High Profile Video Decoder Chip

Résumé:
The increased resolution of Quad Full High Definition (QFHD) offers significantly enhanced visual experience. However, the corresponding huge data throughput of up to 530 Mpixels/s greatly challenges the design of real-time video decoder VLSI with the extensive requirement on both DRAM bandwidth and computational power. In this work, a lossless frame recompression technique and a partial MB reordering scheme are proposed to save the DRAM access of a QFHD video decoder chip. Besides, pipelining and parallelization techniques such as NAL/slice-parallel entropy decoding are implemented to efficiently enhance its computational power. The chip supporting H.264/AVC high profile is fabricated in 90 nm CMOS and verified. It delivers a maximum throughput of 4096×2160@60fps, which is at least 4.3 times higher than the state-of-the-art. DRAM bandwidth requirement is reduced by typically 51%, which fits the design into a 64-bit LPDDR SDRAM interface and results in 58% DRAM power saving. Meanwhile, the core energy is saved by 54% by pipelining and parallelization.

Auteurs: Dajiang Zhou;Jinjia Zhou;Xun He;Jiayi Zhu;Ji Kong;Peilin Liu;Goto, S.;

Apparue dans: IEEE Journal of Solid-State Circuits

Date publication: 04.-2011, volume: 46, issue:4, pages: 777 - 788

Editeur: IEEE

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» A 54–862-MHz CMOS Transceiver for TV-Band White-Space Device Applications

Résumé:
A 54–862-MHz single-chip CMOS transceiver with a single LC voltage-controlled oscillator (VCO) fractional-N synthesizer is developed for TV-band white-space communications and cognitive radio applications. The transceiver is based on a single-conversion zero-IF architecture with integrated harmonic filtering capability. A combined harmonic rejection mixer and coarse RF tracking filter significantly lessens the in-band harmonic emission problem in the transmitter, as well as the harmonic mixing problem in the receiver. A fractional-N phase-locked loop (PLL) with only a single LC VCO and a wideband multimodulus local oscillator (LO) generator seamlessly covers the entire band. A wideband semi-dynamic divide-by-1.5 circuit is adopted in the LO generator to reduce the VCO tuning range requirement by 25 %. A pseudoexponential capacitor bank structure in the LC VCO substantially reduces the K_{rm VCO} and f_{rm step} variations across the total band, which is beneficial for maintaining the PLL loop stability and dynamics over the wide band. The transceiver is implemented in 0.18-\mum CMOS, and operates with a single 1.8-V supply. The transmitter delivers a nominal output power of {-}{\{3}} dBm, and exhibits {rm OP}_{1 {rm {dB}}} of {>} +{\{6.4}} dBm, {rm OIP}_{3} of ${>} +{hbox{15.9}}$ dBm, and error vector magnitude (EVM) of {<} -{\{34.7}} dB for 64-QAM signal. The image and carrier leakage calibration circuits suppress the leakage components below {-}{\{41}} dBc across the entire band. The receiver achieves about 100-dB gain dynamic range, 3.5–6.9-dB noise figure, {<} -{\{29}}-dB EVM, and {-}{\{43.4}}/-{\{59.7}}-dBc third/fifth harmonic mixing suppression. The synthesizer and LO generator achieves the integrated phase noise < {\{0.8}} rms degree over the entire band.

Auteurs: Kim, J.;Lee, S. J.;Kim, S.;Ha, J. O.;Eo, Y. S.;Shin, H.;

Apparue dans: IEEE Transactions on Microwave Theory and Techniques

Date publication: 04.-2011, volume: 59, issue:4, pages: 966 - 977

Editeur: IEEE

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» A 60 GHz Wideband Quadrature-Balanced Mixer Based on 0.13 \\mu{\rm m} RFCMOS Technology

Résumé:
A 60 GHz wideband quadrature-balanced down-conversion mixer employing a new wideband technique with an active feedback has been developed in this work. Fabricated with a 0.13 \mu{rm m} RFCMOS technology, the mixer exhibits a 3 dB IF bandwidth of 5 GHz with a conversion gain of 2.3 dB for a fixed LO frequency of 60 GHz. The mixer also shows an RF bandwidth of 7 GHz with a peak gain of 5.6 dB at 55 GHz. The circuit draws 10.6 mA from 1.3 V supply.

Auteurs: Kim, D.-H.;Kim, S.-J.;Rieh, J.-S.;

Apparue dans: IEEE Microwave and Wireless Components Letters

Date publication: 04.-2011, volume: 21, issue:4, pages: 215 - 217

Editeur: IEEE

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» A 60 GHz Wideband Quadrature-Balanced Mixer Based on 0.13 \\mu{\rm m} RFCMOS Technology

Résumé:
A 60 GHz wideband quadrature-balanced down-conversion mixer employing a new wideband technique with an active feedback has been developed in this work. Fabricated with a 0.13 μm RFCMOS technology, the mixer exhibits a 3 dB IF bandwidth of 5 GHz with a conversion gain of 2.3 dB for a fixed LO frequency of 60 GHz. The mixer also shows an RF bandwidth of 7 GHz with a peak gain of 5.6 dB at 55 GHz. The circuit draws 10.6 mA from 1.3 V supply.

Auteurs: Dong-Hyun Kim;Sung-Jin Kim;Jae-Sung Rieh;

Apparue dans: IEEE Microwave and Wireless Components Letters

Date publication: 04.-2011, volume: 21, issue:4, pages: 215 - 217

Editeur: IEEE

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» A 60-GHz 2-bit Switched-Line Phase Shifter Using SP4T RF-MEMS Switches

Résumé:
This paper presents a V-band 2-bit switched-line phase shifter using dc-contact single-pole four-throw (SP4T) RF microelectromechanical systems (RF-MEMS) switches for 60-GHz applications. The design and measurements of the SP4T RF-MEMS switches and the phase shifter are presented. The phase shifter demonstrates an average insertion loss of 2.5 dB in the 55–65-GHz band with a return loss better than 12 dB for each state. The phase error for each state of the switched-line phase shifter is less than 1° at 60 GHz.

Auteurs: Gong, S.;Shen, H.;Barker, N. S.;

Apparue dans: IEEE Transactions on Microwave Theory and Techniques

Date publication: 04.-2011, volume: 59, issue:4, pages: 894 - 900

Editeur: IEEE

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» A 65 nm CMOS Quad-Band SAW-Less Receiver SoC for GSM/GPRS/EDGE

Résumé:
A quad-band 2.5G receiver is designed to replace the front-end SAW filters with on-chip bandpass filters and to integrate the LNA matching components, as well as the RF baluns. The receiver achieves a typical sensitivity of -110 dBm or better, while saving a considerable amount of BOM. Utilizing an arrangement of four baseband capacitors and MOS switches driven by 4-phase 25% duty-cycle clocks, high-Q BPF's are realized to attenuate the 0 dBm out-of-band blocker. The 65 nm CMOS SAW-less receiver integrated as a part of a 2.5G SoC, draws 55 mA from the battery, and measures an out-of-band 1 dB-compression of greater than +2 dBm. Measured as a stand-alone, as well as the baseband running in call mode in the platform level, the receiver passes the 3GPP specifications with margin.

Auteurs: Mirzaei, A.;Darabi, H.;Yazdi, A.;Zhimin Zhou;Chang, E.;Suri, P.;

Apparue dans: IEEE Journal of Solid-State Circuits

Date publication: 04.-2011, volume: 46, issue:4, pages: 950 - 964

Editeur: IEEE

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» A balanced composite backward and forward compact waveguide based on resonant metamaterials

Résumé:
A balanced composite backward and forward waveguide is presented by using modified split ring resonators. The forbidden band between the forward and backward guided mode is eliminated. Acoaxial feed method is proposed to excite both the forward and backward guided modes. The passband of the proposed structure ranges from 4.28GHz to 6.83GHz, below the cutoff frequency of the fundamental mode of the hollow waveguide (∼15 GHz). Physical size of the waveguide has been dramatically decreased.

Auteurs: Tang, Qi;Meng, Fan-Yi;Wu, Qun;Lee, Jong-Chul;

Apparue dans: Journal of Applied Physics

Date publication: 04.-2011, volume: 109, issue:7, pages: 07A319 - 07A319-3

Editeur: IEEE

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» A basic study of a triangular magnet chain for locomotion control

Résumé:
This paper introduces a theoretical (magnetic and robotic) and experimental study of a robotic locomotion principle utilizing a triangular artificial magnetic chain with a rotating magnetic field for biomedical applications. A three-axis Helmholtz coil system with external controller (joystick) controls the moving direction of the proposed magnet chain according to changes of the plane of the rotating magnetic field. The proposed magnet chain consists of three NdFeB magnets, and its magnetic property depends on dipoles interaction. Also, motion dynamics bring about a magnetic torque analyzed by robotics. A total magnetic moment on the triangular magnet chain provides magnetic torque in the rotating magnetic field, and a geometric property produces a stable movement for robotic locomotion.

Auteurs: Kim, Sung Hoon;Hashi, Shuichiro;Ishiyama, Kazushi;

Apparue dans: Journal of Applied Physics

Date publication: 04.-2011, volume: 109, issue:7, pages: 07E318 - 07E318-3

Editeur: IEEE

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» A Battery-Powered Activity-Dependent Intracortical Microstimulation IC for Brain-Machine-Brain Interface

Résumé:
This paper describes an activity-dependent intracortical microstimulation (ICMS) system-on-chip (SoC) that converts extracellular neural spikes recorded from one brain region to electrical stimuli delivered to another brain region in real time in vivo. The 10.9-mm² SoC incorporates two identical 4-channel modules, each comprising an analog recording front-end with total input noise voltage of 3.12 μV_rms and noise efficiency factor (NEF) of 2.68, 5.9-μW 10-bit successive approximation register analog-to-digital converters (SAR ADCs), 12.4-μW digital spike discrimination processor, and a programmable constant-current microstimulating back-end that delivers up to 94.5 μA with 6-bit resolution to stimulate the cortical tissue when triggered by neural activity. For autonomous operation, the SoC also integrates biasing and clock generation circuitry, frequency-shift-keyed (FSK) transmitter at 433 MHz, and dc-dc converter that generates a power supply of 5.05 V for the microstimulating back-end from a single 1.5-V battery. Measured results from electrical performance characterization and biological experiments with anesthetized rats are presented from a prototype chip fabricated in AMS 0.35 μm two-poly four-metal (2P/4M) CMOS. A noise analysis for the selected low-noise amplifier (LNA) topology is presented that obtains a minimum NEF of 2.33 for a practical design given the technology parameters and power supply voltage. Future considerations in the SoC design with respect to silicon area and power consumption when increasing the number of channels are also discussed.

Auteurs: Azin, M.;Guggenmos, D.J.;Barbay, S.;Nudo, R.J.;Mohseni, P.;

Apparue dans: IEEE Journal of Solid-State Circuits

Date publication: 04.-2011, volume: 46, issue:4, pages: 731 - 745

Editeur: IEEE

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» A Bayesian Approach to Diameter Estimation in the Diameter Control System of Silicon Single Crystal Growth

Résumé:
In the diameter control system of silicon single crystal growth, the variation of the diameter of the aperture (i.e., a halo with high brightness, which appears at the junction of a solid crystal and a liquid solution) is consistent with the change in the diameter of the growing crystal. Therefore, the diameter of the aperture can be used as a control variable for adjusting the casting speed and temperature so that the grown silicon single crystal approximates to a perfect cylinder. It is obvious that the measured diameter of the current aperture plays an important role in the diameter control system of silicon single crystal growth. In fact, the obtained aperture image from a charge-coupled device camera is a halo of ellipses instead of circles. To estimate the diameter (or radius) of the elliptical aperture, we propose a Bayesian approach, in which a Bayesian model is derived to define a posterior distribution for the unknown parameters. This distribution is too complicated for analytical extraction of moments to sample directly. An efficient computational algorithm based on a Markov chain Monte Carlo method is derived to estimate the posterior distribution and draw samples from the distribution. Comparing with the classical Hough transform-based algorithm and the direct least-squares fitting method, the proposed algorithm has higher estimation accuracy. Some simulated and experimental examples are presented to illustrate the algorithm's effectiveness.

Auteurs: Ding Liu;Junli Liang;

Apparue dans: IEEE Transactions on Instrumentation and Measurement

Date publication: 04.-2011, volume: 60, issue:4, pages: 1307 - 1315

Editeur: IEEE

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» A Biomedical Sensor Interface With a sinc Filter and Interference Cancellation

Résumé:
A compact, low-power, digitally-assisted sensor interface for biomedical applications is presented. It exploits oversampling and mixed-signal feedback to reduce system area and power, while making the system more robust to interferers. Antialiasing is achieved using a charge-sampling filter with a sinc frequency response and programmable gain. A mixed-signal feedback loop creates a sharp, programmable notch for interference cancellation. A prototype was implemented in a 0.18-μm CMOS process. The on-chip blocks operate from a 1.5-V supply and consume between 255 nW and 2.5 μW depending on noise and bandwidth requirements.

Auteurs: Bohorquez, J.L.;Yip, M.;Chandrakasan, A.P.;Dawson, J.L.;

Apparue dans: IEEE Journal of Solid-State Circuits

Date publication: 04.-2011, volume: 46, issue:4, pages: 746 - 756

Editeur: IEEE

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» A Car That's Faster Than a Speeding Bullet

Résumé:
In 1997, British Royal Air Force fighter pilot Andy Green broke the world landspeed record at 763 miles per hour (1228 kilometers per hour)-literally faster than some bullets. Now he's gunning for a new record in 2012-driving 1000 mph (1609 km/h) in the new Bloodhound supersonic car.

Auteurs: Karlin, S.;

Apparue dans: IEEE Spectrum

Date publication: 04.-2011, volume: 48, issue:4, pages: 23 - 23

Editeur: IEEE

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» A Car-Seat Example of Automated Anthropomorphic Testing of Fabrics Using Force-Controlled Robot Motions

Résumé:
For the last years, automation is widely used to relieve humans from repetitive tasks, primarily and firstly within manufacturing. However, for products with less ideal (or hard to model) properties, and when forces depends on human interaction, automated testing has not been explored until now.

Auteurs: Valera, A.;Benimeli, F.;Solaz, J.;De Rosario, H.;Robertsson, A.;Nilsson, K.;Zotovic, R.;Mellado, M.;

Apparue dans: IEEE Transactions on Automation Science and Engineering

Date publication: 04.-2011, volume: 8, issue:2, pages: 280 - 291

Editeur: IEEE

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» A Channel Coding Perspective of Collaborative Filtering

Résumé:
We consider the problem of collaborative filtering from a channel coding perspective. We model the underlying rating matrix as a finite alphabet matrix with block constant structure. The observations are obtained from this underlying matrix through a discrete memoryless channel with a noisy part representing noisy user behavior and an erasure part representing missing data. Moreover, the clusters over which the underlying matrix is constant are unknown. We establish a threshold result for this model: if the largest cluster size is smaller than C_1 log(mn) (where the rating matrix is of size m \times n), then the underlying matrix cannot be recovered with any estimator, but if the smallest cluster size is larger than C_2 log(mn), then we show a polynomial time estimator with asymptotically vanishing probability of error. In the case of uniform cluster size, not only the order of the threshold, but also the constant is identified.

Auteurs: Aditya, S. T.;Dabeer, O.;Dey, B. K.;

Apparue dans: IEEE Transactions on Information Theory

Date publication: 04.-2011, volume: 57, issue:4, pages: 2327 - 2341

Editeur: IEEE

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» A Chebyshev-Response Step-Impedance Phase-Inverter Rat-Race Coupler Directly on Lossy Silicon Substrate and Its Gilbert Mixer Application

Résumé:
This paper focuses on the analysis and the design methodology of the step-impedance phase-inverter rat-race coupler on a silicon-based process. The issues of impedance limitation and bandwidth are discussed in detail. Our proposed concept utilizes a high silicon dielectric constant, phase-inverter structure, step-impedance technique, and Chebyshev response to make the rat-race coupler more compact (\sim !{\ {64}}% reduction) and highly balanced over a wide operating bandwidth. Moreover, the inter-digital coplanar stripline used in the step-impedance section effectively reduces the characteristic impedance of the transmission line for large size shrinkage and insertion-loss reduction. The demonstrated step-impedance rat-race coupler directly on silicon substrate has {\ {6-}}\sim {\ {7-}}{\ {dB}} insertion loss from 5 to 15 GHz and small variations in amplitude/phase balance. Compared with our previous work, the proposed rat-race coupler achieves a 3-dB improvement in the insertion loss. Thus, a 0.13-\mu{\ {m}} CMOS Gilbert down-converter with a miniature phase-inverter rat-race coupler at the RF path for wideband single-to-differential signal conversion achieves a noise figure of 16 dB.

Auteurs: Wei, H.-J.;Meng, C.;Yu, S.-W.;Chang, C.-H.;

Apparue dans: IEEE Transactions on Microwave Theory and Techniques

Date publication: 04.-2011, volume: 59, issue:4, pages: 882 - 893

Editeur: IEEE

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» A CMOS 6-Bit 16-GS/s Time-Interleaved ADC Using Digital Background Calibration Techniques

Résumé:
An 8-channel 6-bit 16-GS/s time-interleaved analog- to-digital converter (TI ADC) was fabricated using a 65 nm CMOS technology. Each analog-to-digital channel is a 6-bit flash ADC. Its comparators are latches without the preamplifiers. The input-referred offsets of the latches are reduced by digital offset calibration. The TI ADC includes a multi-phase clock generator that uses a delay-locked loop to generate 8 sampling clocks from a reference clock of the same frequency. The uniformity of the sampling intervals is ensured by digital timing-skew calibration. Both the offset calibration and the timing-skew calibration run continuously in the background. At 16 GS/s sampling rate, this ADC chip achieves a signal-to-distortion-plus-noise ratio (SNDR) of 30.8 dB. The chip consumes 435 mW from a 1.5 V supply. The ADC active area is 0.93 × 1.58 mm².

Auteurs: Chun-Cheng Huang;Chung-Yi Wang;Jieh-Tsorng Wu;

Apparue dans: IEEE Journal of Solid-State Circuits

Date publication: 04.-2011, volume: 46, issue:4, pages: 848 - 858

Editeur: IEEE

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» A CMOS Image Sensor With On-Chip Image Compression Based on Predictive Boundary Adaptation and Memoryless QTD Algorithm

Résumé:
This paper presents the architecture, algorithm, and VLSI hardware of image acquisition, storage, and compression on a single-chip CMOS image sensor. The image array is based on time domain digital pixel sensor technology equipped with nondestructive storage capability using 8-bit Static-RAM device embedded at the pixel level. The pixel-level memory is used to store the uncompressed illumination data during the integration mode as well as the compressed illumination data obtained after the compression stage. An adaptive quantization scheme based on fast boundary adaptation rule (FBAR) and differential pulse code modulation (DPCM) procedure followed by an online, least storage quadrant tree decomposition (QTD) processing is proposed enabling a robust and compact image compression processor. A prototype chip including 64 \times 64 pixels, read-out and control circuitry as well as an on-chip compression processor was implemented in 0.35 \mum CMOS technology with a silicon area of 3.2 \times, {\ {3.0 mm}}^{2} and an overall power of 17 mW. Simulation and measurements results show compression figures corresponding to 0.6–1 bit-per-pixel (BPP), while maintaining reasonable peak signal-to-noise ratio levels.

Auteurs: Chen, S.;Bermak, A.;Wang, Y.;

Apparue dans: IEEE Transactions on Very Large Scale Integration Systems

Date publication: 04.-2011, volume: 19, issue:4, pages: 538 - 547

Editeur: IEEE

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» A CMOS Instrumentation Amplifier With 90-dB CMRR at 2-MHz Using Capacitive Neutralization: Analysis, Design Considerations, and Implementation

Résumé:
The benefits of using “current feedback” in instrumentation amplifier (IA) design are well known. In this paper, we analyze the mismatch mechanisms, both random and systematic types, which influence the common-mode rejection ratio (CMRR) performance of the local current feedback IA topology. We derive analytical expressions for the common-mode gain frequency response due to random mismatches (transconductance, drain-source conductance and parasitic capacitance) and verify the integrity of the analysis through simulation. To address the systematic mismatch in the drain capacitance of the input pair transistors, we employ capacitive neutralization and verify its effectiveness in practice from the fabricated IA chip samples in a 0.35-\mu \{m} CMOS process technology. The measured average common-mode gain improvement for the 20 fabricated samples employing our neutralization technique is about 20 dB at 2 MHz (-3 dB bandwidth). When taking into account the differential gain response (33.7 dB), the average CMRR of the neutralized IA at 2 MHz exceeds 90 dB. The IA occupies an area of 0.068 \{mm}^{2} and dissipates 0.85 mW from a 3-V power supply. The circuit is intended for a wideband bioimpedance spectroscopy application.

Auteurs: Worapishet, A.;Demosthenous, A.;Liu, X.;

Apparue dans: IEEE Transactions on Circuits and Systems I: Regular Papers

Date publication: 04.-2011, volume: 58, issue:4, pages: 699 - 710

Editeur: IEEE

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» A comb-sampling method for enhanced mass analysis in linear electrostatic ion traps

Résumé:
In this paper an algorithm for extracting spectral information from signals containing a series of narrow periodic impulses is presented. Such signals can typically be acquired by pickup detectors from the image-charge of ion bunches oscillating in a linear electrostatic ion trap, where frequency analysis provides a scheme for high-resolution mass spectrometry. To provide an improved technique for such frequency analysis, we introduce the CHIMERA algorithm (Comb-sampling for High-resolution IMpulse-train frequency ExtRAaction). This algorithm utilizes a comb function to generate frequency coefficients, rather than using sinusoids via a Fourier transform, since the comb provides a superior match to the data. This new technique is developed theoretically, applied to synthetic data, and then used to perform high resolution mass spectrometry on real data from an ion trap. If the ions are generated at a localized point in time and space, and the data is simultaneously acquired with multiple pickup rings, the method is shown to be a significant improvement on Fourier analysis. The mass spectra generated typically have an order of magnitude higher resolution compared with that obtained from fundamental Fourier frequencies, and are absent of large contributions from harmonic frequency components.

Auteurs: Greenwood, J. B.;Kelly, O.;Calvert, C. R.;Duffy, M. J.;King, R. B.;Belshaw, L.;Graham, L.;Alexander, J. D.;Williams, I. D.;Bryan, W. A.;Turcu, I. C. E.;Cacho, C. M.;Springate, E.;

Apparue dans: Review of Scientific Instruments

Date publication: 04.-2011, volume: 82, issue:4, pages: 043103 - 043103-12

Editeur: IEEE

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» A Combined State-Space Nodal Method for the Simulation of Power System Transients

Résumé:
This paper presents a new solution method that combines state-space and nodal analysis for the simulation of electrical systems. The presented flexible clustering of state-space-described electrical subsystems into a nodal method offers several advantages for the efficient solution of switched networks, nonlinear functions, and for interfacing with nodal model equations. This paper extends the concept of discrete companion branch equivalent of the nodal approach to state-space described systems and enables natural coupling between them. The presented solution method is simultaneous and enables benefitting from the advantages of two different modeling approaches normally exclusive from one another.

Auteurs: Dufour, C.;Mahseredjian, J.;Bélanger, J.;

Apparue dans: IEEE Transactions on Power Delivery

Date publication: 04.-2011, volume: 26, issue:2, pages: 928 - 935

Editeur: IEEE

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» A Comment on "Performance Analysis of Uplink Cognitive Cellular Networks with Opportunistic Scheduling"

Résumé:
An exact closed-form bit-error-rate (BER) expression is derived for the scheduled cognitive user (CU) in the uplink cellular networks with opportunistic scheduling considered by Li. Simulation results corroborate the theoretical analysis.

Auteurs: Fan, Lisheng;Lei, Xianfu;

Apparue dans: IEEE Communications Letters

Date publication: 04.-2011, volume: 15, issue:4, pages: 361 - 361

Editeur: IEEE

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» A compact model of domain wall propagation for logic and memory design

Résumé:
Current-driven domain wall motion is very promising for low-power, high-density, and high-speed circuits. By combining this shifting scheme with magnetic tunnel junction (MTJ) for reading and writing processes, it opens new routes for nonvolatile logic and memory applications that are crucial for the future of spintronics. This paper reports on a compact model for domain wall-MTJ-based circuit design, simulation, and evaluation. It integrates spin transfer torque mechanism for magnetization reversal and domain wall nucleation, current-driven domain wall pinning/motion behaviors, and tunnel resistance theory of MTJ nanopillar, in which the free layer is one storage element of magnetic stripe. This model is programmed with a very flexible structure to achieve the best simulation precision and efficiency, and provide easy parameter configuration interface. It is compatible with classical computer-aided design environment and can be cosimulated directly with CMOS design kits. By using the compact model, we have successfully simulated a domain wall propagation shift register.

Auteurs: Zhao, W. S.;Duval, J.;Ravelosona, D.;Klein, J.-O.;Kim, J. V.;Chappert, C.;

Apparue dans: Journal of Applied Physics

Date publication: 04.-2011, volume: 109, issue:7, pages: 07D501 - 07D501-3

Editeur: IEEE

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» A compact repetitive high-voltage nanosecond pulse generator for the application of gas discharge

Résumé:
Uniform and stable discharge plasma requires very short duration pulses with fast rise times. A repetitive high-voltage nanosecond pulse generator for the application of gas discharge is presented in this paper. It is constructed with all solid-state components. Two-stage magnetic compression is used to generate a short duration pulse. Unlike in some reported studies, common commercial fast recovery diodes instead of a semiconductor opening switch (SOS) are used in our experiment that plays the role of SOS. The SOS-like effects of four different kinds of diodes are studied experimentally to optimize the output performance. It is found that the output pulse voltage is higher with a shorter reverse recovery time, and the rise time of pulse becomes faster when the falling time of reverse recovery current is shorter. The SOS-like effect of the diodes can be adjusted by changing the external circuit parameters. Through optimization the pulse generator can provide a pulsed voltage of 40 kV with a 40 ns duration, 10 ns rise time, and pulse repetition frequency of up to 5 kHz. Diffuse plasma can be formed in air at standard atmospheric pressure using the developed pulse generator. With a light weight and small packaging the pulse generator is suitable for gas discharge application.

Auteurs: Pang, Lei;Zhang, Qiaogen;Ren, Baozhong;He, Kun;

Apparue dans: Review of Scientific Instruments

Date publication: 04.-2011, volume: 82, issue:4, pages: 043504 - 043504-5

Editeur: IEEE

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» A Compact UWB Antenna for On-Body Applications

Résumé:
A new compact planar ultrawideband (UWB) antenna designed for on-body communications is presented. The antenna is characterized in free space, on a homogeneous phantom modeling a human arm, and on a realistic high-resolution whole-body voxel model. In all configurations it demonstrates very satisfactory features for on-body propagation. The results are presented in terms of return loss, radiation pattern, efficiency, and E-field distribution. The antenna shows very good performance within the 3–11.2 GHz range, and therefore it might be used successfully for the 3.1–10.6 GHz IR-UWB systems. The simulation results for the return loss and radiation patterns are in good agreement with measurements. Finally, a time-domain analysis over the whole-body voxel model is performed for impulse radio applications, and transmission scenarios with several antennas placed on the body are analyzed and compared.

Auteurs: Chahat, N.;Zhadobov, M.;Sauleau, R.;Ito, K.;

Apparue dans: IEEE Transactions on Antennas and Propagation

Date publication: 04.-2011, volume: 59, issue:4, pages: 1123 - 1131

Editeur: IEEE

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» A Comparative 1/f Noise Study of GeOI wafers obtained by the Ge Enrichment Technique & the Smart-Cut Technology

Résumé:
This paper presents an experimental investigation of Low Frequency Noise (LFN) measurements on Germanium-On-Insulator (GeOI) PMOS transistors processed on different wafers. The wafers are obtained by Ge enrichment technique & by Smart CutTM technology. The slow oxide trap densities of back interface are used as a figure of merit to evaluate the process. The Smart CutTM process is evaluated by studying GeOI pMOSFETs, and the enrichment process by studying Si1-xGex (x=25 and 35%) pMOSFETs. The buried oxide is used as a back gate for experimental purposes. The extracted values are of the same order of magnitude for both processes and...

Auteurs: M., Valenza , J., El Husseini , J., Gyani , F., Martinez , M., Bawedin , ...

Apparue dans: Microelectronic Engineering

Date publication: 04.-2011

Editeur: Elsevier B.V.

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» A comparative analysis of Ag and Cu heat sink layers in L10-FePt films for heat-assisted magnetic recording

Résumé:
The magnetic properties, structural properties, and thermal conductivity of FePt films deposited on Ag and Cu heat sink layers designed for use in heat-assisted magnetic recording (HAMR) were investigated. It has been found that FePt films grown on Cu have a well-defined L10-FePt (001) texture while the FePt films grown on Ag appear to be more isotropic. As the thickness of the heat sink layer increases from 15 to 120 nm the coercivity of the FePt films decreases from 1.7 to 1.5 T for Cu and from 1.3 to 1.0 T for Ag. The thermal conductivity measurements, carried out with the “laser-flash” technique, revealed that the overall thermal resistance of the examined structures is dominated by the thermal boundary resistance and the interface effects. The increase in the thickness of Ag and Cu heat sink layers does not lead to the higher effective thermal conductivity of the layered structure in the cross-plane direction. The obtained results are important for optimization of the FePt-based structures for HAMR.

Auteurs: Fernandez, Robert;Teweldebrhan, Desalegne;Zhang, Chen;Balandin, Alexander;Khizroev, Sakhrat;

Apparue dans: Journal of Applied Physics

Date publication: 04.-2011, volume: 109, issue:7, pages: 07B763 - 07B763-3

Editeur: IEEE

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» A Comparative Study of Software Model Checkers as Unit Testing Tools: An Industrial Case Study

Résumé:
Conventional testing methods often fail to detect hidden flaws in complex embedded software such as device drivers or file systems. This deficiency incurs significant development and support/maintenance cost for the manufacturers. Model checking techniques have been proposed to compensate for the weaknesses of conventional testing methods through exhaustive analyses. Whereas conventional model checkers require manual effort to create an abstract target model, modern software model checkers remove this overhead by directly analyzing a target C program, and can be utilized as unit testing tools. However, since software model checkers are not fully mature yet, they have limitations according to the underlying technologies and tool implementations, potentially critical issues when applied in industrial projects. This paper reports our experience in applying Blast and CBMC to testing the components of a storage platform software for flash memory. Through this project, we analyzed the strong and weak points of two different software model checking technologies in the viewpoint of real-world industrial application-counterexample-guided abstraction refinement with predicate abstraction and SAT-based bounded analysis.

Auteurs: Moonzoo Kim;Yunho Kim;Hotae Kim;

Apparue dans: IEEE Transactions on Software Engineering

Date publication: 04.-2011, volume: 37, issue:2, pages: 146 - 160

Editeur: IEEE

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» A Comparative Study on Bubble-Driven Micropumping in Microchannels with Square and Circular Cross Sections

Résumé:
We report experimental evidence that by employing circular flow channels, the maximum pressure head, flow rate and output flow power of a valve-less bubble-driven micropump can be improved by factors of 2.0~2.3, 2.3~2.9 and 3.6~4.6 respectively, when compared with its counterparts with square flow channels having the same hydraulic diameter. It is thus suggested that significant improvements on pumping performance can be achieved by rounding the flow channels of this category of micropumps, which are usually square or rectangular in cross section as fabricated. The geometry-dependent pumping performance is attributed to the different formations of liquid film generated between the...

Auteurs: Ryan J., Lemmens , Dennis Desheng, Meng

Apparue dans: Sensors and Actuators A: Physical

Date publication: 04.-2011

Editeur: Elsevier B.V.

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» A comprehensive study for advanced in-situ contact dry cleaning

Résumé:

Auteurs: An advanced in-situ pre-contact dry cleaning process with fluorine species has been comprehensively investigated to effectively remove the native oxide on the top surface of Ni-salicide layer for ensuring lower contact resistance (Rc) without the dra

Apparue dans: Microelectronic Engineering

Date publication: 04.-2011

Editeur: Elsevier B.V.

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» A constitutive equation for nano-to-macro-scale heat conduction based on the Boltzmann transport equation

Résumé:
A constitutive equation for heat conduction is derived from the exact solution of the Boltzmann transport equation under the relaxation time approximation. This is achieved by a series expansion on multiple space derivatives of the temperature and introducing the concept of thermal multipoles, where the thermal conductivity defined under the framework of the Fourier law of heat conduction is just the first thermal pole. It is shown that this equation generalizes the Fourier law and Cattaneo equation of heat conduction, and it depends strongly on the relative values of the length and time scales compared with the mean-free path and mean-free time of the energy carriers, respectively. In the limiting case of steady-state heat conduction, it is shown that the heat flux vector depends on a spatial scale ratio whose effects are remarkable in the micro-scale spatial domains. By applying a first-order approximation of the obtained thermal multipole expansion to the problem of transient heat conduction across a thin film and comparing the results with the predictions for the same problem using the Fourier, Cattaneo and Boltzmann transport equations, it is shown that our results could be useful in the study of the heat transport in short as well as in long scales of space and time. The common and different features of the multipole expansion compared with the Ballistic-diffusive model of heat conduction are also discussed. Special emphasis is put to the cases where the physical scales of space and time are comparable to the mean-free path and mean-free time of the energy carriers.

Auteurs: Ordonez-Miranda, J.;Yang, Ronggui;Alvarado-Gil, J. J.;

Apparue dans: Journal of Applied Physics

Date publication: 04.-2011, volume: 109, issue:8, pages: 084319 - 084319-8

Editeur: IEEE

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» A Construction of a New Family of M-ary Sequences With Low Correlation From Sidel'nikov Sequences

Résumé:
In this paper, a new family of M-ary sequences of period p^{n} -1 is proposed. The proposed family is constructed by the addition of cyclic shifts of an M-ary Sidel'nikov sequence and its reverse sequence. The number of sequences contained in this family is about (M-1)^{2} times of their period and the maximum magnitude of their correlation values is upper bounded by 4 sqrt {p^{n} } +5.

Auteurs: Chung, J.-S.;No, J.-S.;Chung, H.;

Apparue dans: IEEE Transactions on Information Theory

Date publication: 04.-2011, volume: 57, issue:4, pages: 2301 - 2305

Editeur: IEEE

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» A Control Strategy for Islanded Microgrids With DC-Link Voltage Control

Résumé:
New opportunities for optimally integrating the increasing number of distributed-generation (DG) units in the power system rise with the introduction of the microgrid. Most DG units are connected to the microgrid via a power-electronic inverter with dc link. Therefore, new control methods for these inverters need to be developed in order to exploit the DG units as effectively as possible in case of an islanded microgrid. In the literature, most control strategies are based on the conventional transmission grid control or depend on a communication infrastructure. In this paper, on the other hand, an alternative control strategy is proposed based on the specific characteristics of islanded low-voltage microgrids. The microgrid power is balanced by using a control strategy that modifies the set value of the rms microgrid voltage at the inverter ac side as a function of the dc-link voltage. In case a certain voltage, which is determined by a constant-power band, is surpassed, this control strategy is combined with P/V -droop control. This droop controller changes the output power of the DG unit and its possible storage devices as a function of the grid voltage. In this way, voltage-limit violation is avoided. The constant-power band depends on the characteristics of the generator to avoid frequent changes of the power of certain DG units. In this paper, it is concluded that the new control method shows good results in power sharing, transient issues, and stability. This is achieved without interunit communication, which is beneficial concerning reliability issues, and an optimized integration of the renewable energy sources in the microgrid is obtained.

Auteurs: Vandoorn, T.L.;Meersman, B.;Degroote, L.;Renders, B.;Vandevelde, L.;

Apparue dans: IEEE Transactions on Power Delivery

Date publication: 04.-2011, volume: 26, issue:2, pages: 703 - 713

Editeur: IEEE

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» A control theoretic approach to malaria immunotherapy with state jumps?

Résumé:
We investigate a control method for malaria dynamics to boost the immune response using a model-based approach. The idea of state jump is introduced and discussed using a hybrid model. To implement the state jumps we use a physiologically feasible method for the biological system, whereby the introduction of a pathogen into the system steers it to a desirable status. It is noted that we take advantage of a pathogen to implement state jumps in the system. The study is supported by recently reported experimental results.

Auteurs: H., Chang , A., Astolfi , H., Shim

Apparue dans: Automatica

Date publication: 04.-2011

Editeur: Elsevier B.V.

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» A Correction of Spectral Correlation Function Expression for OFDM Signals

Résumé:
This letter describes the correction of the existing Spectral Correlation Function (SCF) expression of orthogonal frequency division multiplexing (OFDM) signals. The influence of modulated sequences to the cyclostationarity of SCF is introduced, which means the cyclic frequencies of SCF are related to both the symbol period and the modulated sequences period. Theoretical analysis is also validated by simulation results.

Auteurs: Cui, Weiliang;Jiang, Hua;Li, Jianqiang;Wang, Quan;

Apparue dans: IEEE Communications Letters

Date publication: 04.-2011, volume: 15, issue:4, pages: 446 - 448

Editeur: IEEE

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» A Cost-Effective High-Efficiency Power Conditioner With Simple MPPT Control Algorithm for Wind-Power Grid Integration

Résumé:
In this paper, a novel grid integration system for a variable-speed wind turbine using an interior permanent-magnet synchronous generator (IPMSG) is developed. The power conditioner system (PCS) consists of a series-type 12-pulse uncontrolled diode rectifier powered by a phase-shifting transformer and then cascaded to a pulsewidth-modulated (PWM) voltage source inverter. The active current of the grid-side PWM inverter is only controlled to follow the optimal active current reference which is determined by using a simple maximum power point tracking (MPPT) control strategy. The MPPT algorithm requires only three sensors in order to track the maximum power of the wind turbine. The most significant advantage of the proposed system is that the passive filter together with a series-type 12-pulse rectifier provides high efficiency by compensating the power factor angle of the IPMSG and suppresses distortions presented in the IPMSG voltages and currents. The laboratory results indicate that the proposed construction and scheme are simple, cheap, and efficient.

Auteurs: Nishida, K.;Ahmed, T.;Nakaoka, M.;

Apparue dans: IEEE Transactions on Industry Applications

Date publication: 04.-2011, volume: 47, issue:2, pages: 893 - 900

Editeur: IEEE

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» A Creep-Immune Electrostatic Actuator for RF-MEMS Tunable Capacitor

Résumé:
A high creep-immunity MEMS actuator is proposed for RF-MEMS tunable capacitor. The creep-immunity is attained by using silicon nitride, SiN, for the spring portions, where the stress is concentrated. Compared with an aluminum spring, the creep-induced deformation is reduced by a factor of 23 at 100°C. We also confirmed by a billion cycle test that the SiN spring does not develop a brittle fracture.

Auteurs: Etsuji, Ogawa , Tamio, Ikehashi , Tomohiro, Saito , Hiroaki, Yamazaki , Kei, Masunishi , ...

Apparue dans: Sensors and Actuators A: Physical

Date publication: 04.-2011

Editeur: Elsevier B.V.

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» A Critical Assessment of the Closed-Loop Bulk Current Injection Immunity Test Performed in Compliance With ISO 11452-4

Résumé:
The closed-loop bulk current injection (BCI) method employed to measure the immunity to electromagnetic interference of an electronic equipment in compliance with the ISO 11452-4 standard is critically assessed on the basis of an experimental characterization of its test setup. It is highlighted that, above 100 MHz, the injected bulk current estimated by the calibration procedure described in the standard is significantly different from the actual bulk current injected into the connector of the equipment under test (EUT) during BCI tests. Such a discrepancy gives rise to unreliable BCI immunity test results highlighting susceptibility issues that are not related with the actual susceptibility of the EUT.

Auteurs: Crovetti, P.S.;Fiori, F.;

Apparue dans: IEEE Transactions on Instrumentation and Measurement

Date publication: 04.-2011, volume: 60, issue:4, pages: 1291 - 1297

Editeur: IEEE

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» A cryogenic surface-electrode elliptical ion trap for quantum simulation

Résumé:
Two-dimensional crystals of trapped ions are a promising system with which to implement quantum simulations of challenging problems such as spin frustration. Here, we present a design for a surface-electrode elliptical ion trap which produces a 2-D ion crystal and is amenable to microfabrication, which would enable higher simulated coupling rates, as well as interactions based on magnetic forces generated by currents which may be incorporated into the trap structure. Working in an 11 K cryogenic environment, we experimentally verify to within 10% a numerical model of the structure of ion crystals in the trap, given the measured trap anisotropy. We also explore the possibility of implementing quantum simulation using magnetic forces, and calculate J-coupling rates on the order of 10³ s^-1 for a trap scale of 10 μm, using a current of 1 A.

Auteurs: Clark, Robert J.;Lin, Ziliang;Diab, Kenan S.;Chuang, Isaac L.;

Apparue dans: Journal of Applied Physics

Date publication: 04.-2011, volume: 109, issue:7, pages: 076103 - 076103-3

Editeur: IEEE

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» A data-driven model simulating primary infection probabilities of cucumber downy mildew for use in early warning systems in solar greenhouses

Résumé:
Highlights: ? The model is the foundation of disease early warning systems. ? The sensors and model were used to measure leaf wetness duration for disease warning. ? The input parameters of model were readily available and appropriately limited in number. ? The warnings could be provided more than 2 d before the symptoms appeared. ? The predicted probability for disease occurrence using the early warning model was 96%.

Auteurs: Treatment during the primary infection phase is essential for controlling cucumber downy mildew in solar greenhouses. An early warning model applicable to this phase would represent a foundation for early warning systems for managing the disease and

Apparue dans: Computers and Electronics in Agriculture

Date publication: 04.-2011

Editeur: Elsevier B.V.

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» A Data-Mining-Based Methodology for Transmission Expansion Planning

Résumé:
Analyzing electrical and economical locational marginal pricing (LMP) values can help operators in the electric power sector plan future investments and network expansion.

Auteurs: Ferreira, Judite;Ramos, Sergio;Vale, Zita;Soares, Joao;

Apparue dans: IEEE Intelligent Systems

Date publication: 04.-2011, volume: 26, issue:2, pages: 28 - 37

Editeur: IEEE

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» A Detailed Analytical Model of a Salient-Pole Synchronous Generator Under Dynamic Eccentricity Fault

Résumé:
In this paper, a new detailed analytical model of a salient-pole synchronous generator (SPSG) under dynamic eccentricity (DE) is presented which is capable of accounting for the effects of magnetic saturation, rotor pole shoe saliency, and space distribution of stator phases and rotor winding. A real form of rotor pole shoes is taken into account in the proposed SPSG air-gap function distribution. Saturation effects incorporate into the air-gap function of SPSG as a simple proposed analytic equation that varies by the generator load and operating condition. Furthermore, variation of the resulted air-gap distribution of SPSG in the presence of DE fault is then computed precisely and the inverse air-gap function calculated using Fourier series in order to compute time varying self- and mutual-inductances of stator phases and rotor winding via the modified winding function approach (MWFA). The computed inductances are used for simulation of SPSG and studying the frequency spectrum of stator line current in the presence of DE fault. It is shown that the results of proposed model are closer to the finite-element (FE) computation results compared to the available analytic models.

Auteurs: Babaei, M.;Faiz, J.;Ebrahimi, B. M.;Amini, S.;Nazarzadeh, J.;

Apparue dans: IEEE Transactions on Magnetics

Date publication: 04.-2011, volume: 47, issue:4, pages: 764 - 771

Editeur: IEEE

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» A Digital Signal Processing Module for Ge Semiconductor Detectors

Résumé:
We have developed a digital signal processing module (APV7109) for a germanium semiconductor detector. The benchmark test of this module has shown good energy resolution and high throughput compared with conventional analog modules. By adding an extension module, the APV7109 can perform more advanced on-line calculations using the pulse shapes delivered by the on-board programmable logic. Therefore, user defined algorithms for pulse shape analysis can be used to adapt this module to various applications. Tests have demonstrated the feasibility of this extensible design.

Auteurs: Fukuchi, T.;Arai, Y.;Watanabe, F.;Motomura, S.;Takeda, S.;Kanayama, Y.;Haba, H.;Watanabe, Y.;Enomoto, S.;

Apparue dans: IEEE Transactions on Nuclear Science

Date publication: 04.-2011, volume: 58, issue:2, pages: 461 - 467

Editeur: IEEE

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» A Digitally-Calibrated Phase-Locked Loop With Supply Sensitivity Suppression

Résumé:
A digitally-calibrated technique to suppress the supply voltage sensitivity of a phase-locked loop (PLL) is presented. The voltage-controlled ring oscillator with an additional opposite-supply-sensitivity pair is digitally calibrated to suppress the supply voltage sensitivity. The circuit is fabricated in a 0.18-\mum CMOS technology and the core area occupies 0.235 mm^{2}. The total power consumption is 16.2 mW for a supply voltage of 1.8 V and an operating frequency of 1.5 GHz. For a 100 mV_{rm pp}, 110 kHz sinusoidal waveform noise applied to the supply, the measured rms jitters without and with calibration are 16.5 and 9.7 ps, respectively, while this PLL works at 1.5 GHz. This PLL achieves the rms jitter improvement by a factor of 41.2% under the proposed digitally-calibrated technique.

Auteurs: Kao, S.-Y.;Liu, S.-I.;

Apparue dans: IEEE Transactions on Very Large Scale Integration Systems

Date publication: 04.-2011, volume: 19, issue:4, pages: 592 - 602

Editeur: IEEE

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» A Distributed Model for Border Traps in \ {Al}_{2} \ {O}_{3}-\ {InGaAs} MOS Devices

Résumé:
A distributed border trap model based on tunneling between the semiconductor surface and trap states in the gate dielectric film is formulated to account for the observed frequency dispersion in the capacitance and conductance of Al₂O₃/InGaAs MOS devices biased in accumulation. The distributed circuit model is more physical and descriptive than previous lumped circuit border trap models in the literature. The distributed model correctly depicts the frequency dependence of both capacitance and conductance data in accumulation. A border trap volume density is extracted from the quantitative agreement with measured data.

Auteurs: Yu Yuan;Lingquan Wang;Bo Yu;Byungha Shin;Jaesoo Ahn;McIntyre, P.C.;Asbeck, P.M.;Rodwell, M.J.W.;Yuan Taur;

Apparue dans: IEEE Electron Device Letters

Date publication: 04.-2011, volume: 32, issue:4, pages: 485 - 487

Editeur: IEEE

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» A Distributed Model for Border Traps in \{Al}_{2} \{O}_{3}-\{InGaAs} MOS Devices

Résumé:
A distributed border trap model based on tunneling between the semiconductor surface and trap states in the gate dielectric film is formulated to account for the observed frequency dispersion in the capacitance and conductance of \{Al}_{2}\{O}_{3}/\{InGaAs} MOS devices biased in accumulation. The distributed circuit model is more physical and descriptive than previous lumped circuit border trap models in the literature. The distributed model correctly depicts the frequency dependence of both capacitance and conductance data in accumulation. A border trap volume density is extracted from the quantitative agreement with measured data.

Auteurs: Yuan, Y.;Wang, L.;Yu, B.;Shin, B.;Ahn, J.;McIntyre, P. C.;Asbeck, P. M.;Rodwell, M. J. W.;Taur, Y.;

Apparue dans: IEEE Electron Device Letters

Date publication: 04.-2011, volume: 32, issue:4, pages: 485 - 487

Editeur: IEEE

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» A DOST based approach for the condition monitoring of 11 kV distribution line insulators

Résumé:
The diminishing trend of reliability owing to possible power system failures has become a serious concern for the power system as a whole. It has necessitated the development of advanced protection methodologies employing advanced information technology and substation monitoring system (SMS) constitutes an integral part of such methodologies. The proposed scheme for condition monitoring of insulators, which serves as an augmented feature of SMS, aims at alleviating overall system reliability as well as power quality because cracked insulators cause disruption of power, thereby incurring heavy loss to the power system utilities. The image processing based video surveillance (VS) is incorporated to dispense with the cumbersome and time consuming conventional manual on-site detection using discrete orthogonal S-transform (DOST) in conjunction with some intelligent classification algorithms to ascertain the condition of the insulators.

Auteurs: Jaya Bharata Reddy, M.;Karthik Chandra, B.;Mohanta, D.K.;

Apparue dans: IEEE Transactions on Dielectrics and Electrical Insulation

Date publication: 04.-2011, volume: 18, issue:2, pages: 588 - 595

Editeur: IEEE

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» A Dual-Shader 3-D Graphics Processor With Fast 4-D Vector Inner Product Units and Power-Aware Texture Cache

Résumé:
This paper presents a fully programmable 3-D graphics processor using unified shaders for mobile environment. In the system level, we adopted dual-core, dual-issue VLIW, and multithreading methods to utilize instruction, data, and task level parallelism in the graphics applications. In the shader core level, a novel IEEE-754 compliant 4-D vector inner product arithmetic unit and a configurable texture cache are proposed. Using these methods, the proposed processor achieves 143 Mvertices/s and 2.3 Gtexels/s consuming the power of 367 mW. The evaluation shows significant performance and power-delay product benefits. For real graphics applications, test results indicate 2.07 times improvement in performance and 34% reduction in power-delay product compared to previous mobile 3-D graphics processors. The proposed 3-D graphics processor is implemented in 4.5,\times,4.5 ^2mm using 0.18-\mum CMOS technology.

Auteurs: Yoon, J.-S.;Yu, C.-H.;Kim, D.;Kim, L.-S.;

Apparue dans: IEEE Transactions on Very Large Scale Integration Systems

Date publication: 04.-2011, volume: 19, issue:4, pages: 525 - 537

Editeur: IEEE

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» A dynamic data-based model describing nephropathia epidemica in Belgium

Résumé:
Highlights: ? We quantified the dynamics of NE cases in Belgium with dynamic data-based model. ? First we used just average monthly precipitation and temperature as inputs. ? To improve the result, estimated carrying capacity from SIR model was used as a third input. ? Combining the two models, we managed to explain the dynamics of NE cases in Belgium.

Auteurs: Nephropathia epidemica (NE) is a human infection caused by Puumala virus (PUUV), which is naturally carried and shed by bank voles (Myodes glareolus). Population dynamics and infectious diseases in general, such as NE, have often been modelled with m

Apparue dans: Biosystems Engineering

Date publication: 04.-2011

Editeur: Elsevier B.V.

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» A dynamic linearization concept for piezoelectric actuators

Résumé:
We present a linearization circuit based on a capacitive Wheatstone bridge that is able to set a desired polarization in a piezoactuator. The system is meant to be used for dynamic actuation in a broad frequency range. A general nonlinear model for piezoactuators is presented in which two nonlinear sub-systems are cascaded: the electric-field-to-polarization (E-P) and the polarization-to-strain (P-x) blocks. The inversion of the latter sub-system in combination with the linearization bridge results in a reduction of up to 19 dB of the harmonic distortion of the actuator's mechanical displacement.

Auteurs: Biancuzzi, G.;Haller, D.;Lemke, T.;Wischke, M.;Goldschmidtboeing, F.;Woias, P.;

Apparue dans: IEEE Transactions on Ultrasonics, Ferroelectrics and Frequency Control

Date publication: 04.-2011, volume: 58, issue:4, pages: 689 - 697

Editeur: IEEE

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» A Fast and Accurate Method to Study the Impact of Interface Traps on Germanium MOS Performance

Résumé:
A technique is presented to study the electrostatic degradation of key germanium metal–oxide–semiconductor field-effect transistor (MOSFET) performance metrics such as the subthreshold slope {rm SS}, the drive current, and the off-state current. This is calculated using the superposition of the contributions from individual trap profiles, arising from a piecewise approximation of any arbitrary interface-trap spectrum. A technology computer-aided design simulation using this approach has been directly applied to the electrical evaluation of various scaled Ge p-channel FETs with different passivation schemes. The relative {rm SS} degradation due to interface traps is shown to be independent of the gate length, even in scaled devices exhibiting short-channel effects. Additionally, a linear dependence of the relative degradation with an equivalent oxide thickness (EOT) is observed. As such, a transistor's subthreshold performance is less impacted by a given concentration of interface traps, as the EOT is further reduced. Finally, the MOSFET drive current is shown to be degraded due to interface traps, mainly through additional scattering in the channel, while the electrostatic effect is rather small.

Auteurs: Hellings, G.;Eneman, G.;Mitard, J.;Martens, K.;Wang, W.-E;Hoffmann, T.;Meuris, M.;De Meyer, K.;

Apparue dans: IEEE Transactions on Electron Devices

Date publication: 04.-2011, volume: 58, issue:4, pages: 938 - 944

Editeur: IEEE

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» A Fast H.264/AVC-Based Stereo Video Encoding Algorithm Based on Hierarchical Two-Stage Neural Classification

Résumé:
Stereo video, targeting at matching what the humans see in the real world, offers depth perception on observed scenes. The problem of compressing such a huge amount of video data has received considerable attention in the past few years. Its challenge comes from the much more complicated parameter selection (e.g., mode decision) process than single-channel video coding. To cope with this problem, the currently developed H.264/AVC-based JMVM platform is adopted here for implementation, where the encoding of the left-view channel is purely based on predictions from the temporal domain, while for the right-view channel, combined predictions from the temporal and the inter-view domains are exploited and a hierarchical two-stage neural classifier is designed for fast mode decision. The first-stage neural classifier determines candidates of block partition for each macroblock, while the second-stage classifier aims to choose the most probable prediction sources among the temporally forward/backward and inter-view directions. All input features for both stages of neural classifiers are calculated from simple inter-frame and inter-view analyses. In our scheme, the popular fast motion estimation schemes can be also cooperated for further speedup. Experiment results reveal that our proposed algorithm is capable of achieving up to 97% of time savings with nearly ignorable quality degradation and acceptable bit-rate increase (up to 5.67%).

Auteurs: Chiang, J.-C.;Chen, W.-C.;Liu, L.-M.;Hsu, K.-F.;Lie, W.-N.;

Apparue dans: IEEE Journal of Selected Topics in Signal Processing

Date publication: 04.-2011, volume: 5, issue:2, pages: 309 - 320

Editeur: IEEE

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» A fast hybrid algorithm combining regularized motion tracking and predictive search for reducing the occurrence of large displacement errors

Résumé:
A hybrid approach that inherits both the robustness of the regularized motion tracking approach and the efficiency of the predictive search approach is reported. The basic idea is to use regularized speckle tracking to obtain highquality seeds in an explorative search that can be used in the subsequent intelligent predictive search. The performance of the hybrid speckle-tracking algorithm was compared with three published speckle-tracking methods using in vivo breast lesion data. We found that the hybrid algorithm provided higher displacement quality metric values, lower root mean squared errors compared with a locally smoothed displacement field, and higher improvement ratios compared with the classic block-matching algorithm. On the basis of these comparisons, we concluded that the hybrid method can further enhance the accuracy of speckle tracking compared with its real-time counterparts, at the expense of slightly higher computational demands.

Auteurs: Jiang, J.;Hall, T.J.;

Apparue dans: IEEE Transactions on Ultrasonics, Ferroelectrics and Frequency Control

Date publication: 04.-2011, volume: 58, issue:4, pages: 730 - 736

Editeur: IEEE

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» A feature extraction software tool for agricultural object-based image analysis

Résumé:
Highlights: ? We present a new software tool to extract from images a set of descriptive features. ? Features inform about spectral, textural, structural and shape properties of image-objects. ? This tool is applied in a specific agricultural study case to classify land uses/land covers. ? Results show that the combined use of these features allows for classify complex landscapes.

Auteurs: A software application for automatic descriptive feature extraction from image-objects, FETEX 2.0, is presented and described in this paper. The input data include a multispectral high resolution digital image and a vector file in shapefile format co

Apparue dans: Computers and Electronics in Agriculture

Date publication: 04.-2011

Editeur: Elsevier B.V.

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» A first principles theoretical examination of graphene-based field effect transistors

Résumé:
This paper presents an in-depth theoretical examination of graphene-based field effect transistors, looking at thermal statistics, electrostatics, and electrodynamics. Using a first principles approach, the unique behavior observed in graphene-based field effect transistors, such as the V-shaped transfer characteristic, limited channel pinch-off, and lack of off-state (under gate modulation), are described. Unlike previous attempts, a description of both drift and diffusion currents in the device is presented. The effect of external resistance on steady-state and high-frequency performance is examined. Comparisons of the theoretical results to experimental results are made and show good agreement. Finally, the theoretical work in this paper is used as a basis to discuss the possible source of some observed behavior in practical graphene-based field effect transistors.

Auteurs: Champlain, James G.;

Apparue dans: Journal of Applied Physics

Date publication: 04.-2011, volume: 109, issue:8, pages: 084515 - 084515-19

Editeur: IEEE

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» A flex-compressive-mode piezoelectric transducer for mechanical vibration/strain energy harvesting

Résumé:
A piezoelectric transducer for harvesting energy from ambient mechanical vibrations/strains under pressure condition was developed. The proposed transducer was made of two ring-type piezoelectric stacks, one pair of bow-shaped elastic plates, and one shaft that pre-compresses them. This transducer works in flex-compressive (F-C) mode, which is different from a conventional flex-tensional (F-T) one, to transfer a transversely applied force F into an amplified longitudinal force N pressing against the two piezo-stacks via the two bowshaped elastic plates, generating a large electric voltage output via piezoelectric effect. Our experimental results show that without an electric load, an F-C mode piezo-transducer could generate a maximum electric voltage output of up to 110 Vpp, and with an electric load of 40 κΩ, it a maximum power output of 14.6 mW under an acceleration excitation of 1 g peak-peak at the resonance frequency of 87 Hz.

Auteurs: Li, X.;Guo, M.;Dong, S.;

Apparue dans: IEEE Transactions on Ultrasonics, Ferroelectrics and Frequency Control

Date publication: 04.-2011, volume: 58, issue:4, pages: 698 - 703

Editeur: IEEE

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» A four nation survey of farm information management and advanced farming systems: A descriptive analysis of survey responses

Résumé:
Highlights: ? Survey of four EU countries' information management and precision farming. ? Study was on time saving using FIMS in Denmark, Finland, Germany and Greece. ? Results suggest that there are differences in weekly hours allocated to office tasks. ? Benefits exists for introducing labour saving Farm Information Management Systems. ? Respondents (40%) unsure using computers for official institutions and consumers.

Auteurs: The aim of this paper is to present the descriptive results of the survey responses that explore the perception of advanced information systems among four European countries: i.e. Denmark, Finland, Germany and Greece. The study evaluates the potentia

Apparue dans: Computers and Electronics in Agriculture

Date publication: 04.-2011

Editeur: Elsevier B.V.

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» A Framework to Model the Topological Structure of Supply Networks

Résumé:
Topological structure is considered more and more important in managing a supply network or predicting its development. In this paper, a new framework is proposed to model the topological structure of supply networks, where different types of supply networks can be created just by introducing different supplier-customer connecting rules. Generally, the networks created in the framework are much different from the random networks with the same degree sequences. The revealed phenomenon suggests that real-world supply networks may benefit from its intrinsic mechanism on flexibility, efficiency, and robustness to target attacks.

Auteurs: Xuan, Q.;Du, F.;Li, Y.;Wu, T.-J.;

Apparue dans: IEEE Transactions on Automation Science and Engineering

Date publication: 04.-2011, volume: 8, issue:2, pages: 442 - 446

Editeur: IEEE

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» A Front End for Discriminative Learning in Automatic Modulation Classification

Résumé:
This work presents a novel method for automatic modulation classification based on discriminative learning. The features are the ordered magnitude and phase of the received symbols at the output of the matched filter. The results using the proposed front end and support vector machines are compared to other techniques. Frequency offset is also considered and the results show that in this condition the new method significantly outperforms two cumulant-based classifiers.

Auteurs: Muller, Francisco C. B. F.;Cardoso Jr., Claudomir;Klautau, Aldebaro;

Apparue dans: IEEE Communications Letters

Date publication: 04.-2011, volume: 15, issue:4, pages: 443 - 445

Editeur: IEEE

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» A Fully Characterizable Asynchronous Multiphase Delay Generator

Résumé:
A fully characterizable, 128-stage asynchronous Multiphase Delay Generator (MDG) integrated in standard 0.35 \mu{\ {m}} CMOS technology is presented. The circuit consists of a mirror Voltage-Controlled Delay Line (VCDL), driven by a Delay-Locked Loop (DLL), and an analog memory block. The master DLL ensures the stability over temperature and the absolute precision of the delay, whereas the mirror VCDL allows an asynchronous operation of the MDG with respect to the DLL reference clock. The memory block carries out a precise stage-to-stage delay and jitter characterization by analog sampling the state of the mirror VCDL upon an external request. Two versions of the circuit differing by their VCDL layout configurations were processed in order to compare their absolute time accuracy and jitter performance. In the first variant the two delay lines were laid out in an interlaced arrangement, whereas in the second, the mirror VCDL was positioned under the master VCDL. A maximal temporal dynamic range of 125 ps–1 ns was achieved. The single-stage delay variation with temperature was less than 1% over the 10–60^{\circ}{\ {C}} range considered. The mean RMS jitter level per stage remained below 3% of the elementary delay over the entire dynamic range of the MDG for both circuit versions.

Auteurs: Zlatanski, M.;Uhring, W.;Le Normand, J.-P.;Mathiot, D.;

Apparue dans: IEEE Transactions on Nuclear Science

Date publication: 04.-2011, volume: 58, issue:2, pages: 418 - 425

Editeur: IEEE

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» A Fully Flexible Valve Actuation System for Internal Combustion Engines

Résumé:
The automotive industry has been under continued pressure to improve fuel efficiency because of air pollution, global warming, and rising gasoline prices. One technology to address this need is electronic valve timing. It promises to achieve fuel savings of 10%-15% by reducing pumping losses, introducing cylinder deactivation, and enabling new combustion strategies, like homogeneous charge compression ignition. To date, valve actuators for this application primarily rely on resonant spring arrangements to achieve the necessary dynamics. This leads to a fixed amplitude of the valve trajectory and only allows for variable valve timing. In this paper, a fully flexible valve actuation system for intake valves is introduced that provides variable lift in addition to variable timing, without reducing valve dynamics or energy efficiency. Optimization procedures for the mechanical system, the servo motor selection, and the valve trajectory are presented. The combined effect of these optimizations leads to valve accelerations that are an order of magnitude higher than conventional electric servo systems. Simulations and an experimental test bed are used to validate the system performance. A comparison with other electronic valve actuation systems confirms the excellent performance of this approach.

Auteurs: Junfeng Zhao;Seethaler, R.J.;

Apparue dans: IEEE/ASME Transactions on Mechatronics

Date publication: 04.-2011, volume: 16, issue:2, pages: 361 - 370

Editeur: IEEE

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» A Geometric Approach to Improve Interference Mitigation in Multi-User Detection and Equalization

Résumé:
We apply maximal asymptotic conditional efficiency joint successive interference cancellation (MACE-JSIC) to frequency-selective channel equalization and propose improvements that extend MACE-JSIC detection to the broader paradigm of time-varying and imprecisely known communication systems. The need for expensive redesign to include any change in the interfering signals is a fundamental limitation of MACE-JSIC detection despite its high performance and low detection complexity. In this work, we derive sufficiency criteria that reduce maximum asymptotic efficiency (MAE) detection to low-complexity decorrelation and exploit this relationship to extend the MACE-JSIC approach to time-varying communication systems. Simulations on several multi-user systems and frequency-selective channels demonstrate that the performance of the proposed detectors is consistent with theoretical expectations.

Auteurs: Gupta, A.S.;Nelson, J.K.;Weiwei Zhou;Singer, A.C.;Preisig, J.;

Apparue dans: IEEE Transactions on Signal Processing

Date publication: 04.-2011, volume: 59, issue:4, pages: 1694 - 1705

Editeur: IEEE

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» A giant magnetoresistance ring-sensor based microsystem for magnetic bead manipulation and detection

Résumé:
In this paper a novel spin valve giant magnetoresistance (GMR) ring-sensor integrated with a microstructure is proposed for concentrating, trapping, and detecting superparamagnetic beads (SPBs). Taking advantage of the fact that SPBs can be manipulated by an external magnetic field, a unique arrangement of conducting microrings is utilized to manipulate the SPBs toward the GMR sensing area in order to increase the reliability of detection. The microrings are arranged and activated in such a manner so as to enable the detection of minute concentrations of SPBs in a sample. Precise manipulation is achieved by applying current sequentially to the microrings. The fabricated ring-shaped GMR element is located underneath the innermost ring and has a magnetoresistance of approximately 5.9%. By the performed experiments it was shown that SPBs could be successfully manipulated toward the GMR sensing zone.

Auteurs: Gooneratne, Chinthaka P.;Giouroudi, Ioanna;Liang, Cai;Kosel, Jurgen;

Apparue dans: Journal of Applied Physics

Date publication: 04.-2011, volume: 109, issue:7, pages: 07E517 - 07E517-3

Editeur: IEEE

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» A Goldschmidt Division Method With Faster Than Quadratic Convergence

Résumé:
A new method to implement faster than quadratic convergence for Goldschmidt division using simple logic circuits is presented. While the approximate quotient converges quadratically in conventional Goldschmidt division, the new method achieves nearly cubic convergence. Although division with cubic convergence has been regarded as impractical due to its complexity, the proposed method reduces the logic complexity and the delay by using an approximate squarer with a simple logic implementation and a redundant binary Booth recoder. It is especially effective in a system that already has a radix-8 multiplier. As a result, the effective area for the reciprocal table can be reduced by 25.4%. The proposed method has been verified by SystemC and Verilog models. The final results are confirmed by simulation with both random double precision numbers and an exhaustive suite of 17-bit test vectors.

Auteurs: Kong, I.;Swartzlander, E. E.;

Apparue dans: IEEE Transactions on Very Large Scale Integration Systems

Date publication: 04.-2011, volume: 19, issue:4, pages: 696 - 700

Editeur: IEEE

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» A Hardware-in-the-Loop Simulation Platform for the Verification and Validation of Safety Control Systems

Résumé:
Verification and validation (V&V) of safety control system quality and performance is required prior to installing control system hardware within nuclear power plants (NPPs). Thus, the objective of the hardware-in-the-loop (HIL) platform introduced in this paper is to verify the functionality of these safety control systems. The developed platform provides a flexible simulated testing environment which enables synchronized coupling between the real and simulated world. Within the platform, National Instruments (NI) data acquisition (DAQ) hardware provides an interface between a programmable electronic system under test (SUT) and a simulation computer. Further, NI LabVIEW resides on this remote DAQ workstation for signal conversion and routing between Ethernet and standard industrial signals as well as for user interface. The platform is applied to the testing of a simplified implementation of Canadian Deuterium Uranium (CANDU) shutdown system no. 1 (SDS1) which monitors only the steam generator level of the simulated NPP. CANDU NPP simulation is performed on a Darlington NPP desktop training simulator provided by Ontario Power Generation (OPG). Simplified SDS1 logic is implemented on an Invensys Tricon v9 programmable logic controller (PLC) to test the performance of both the safety controller and the implemented logic. Prior to HIL simulation, platform availability of over 95% is achieved for the configuration used during the V&V of the PLC. Comparison of HIL simulation results to benchmark simulations shows good operational performance of the PLC following a postulated initiating event (PIE).

Auteurs: Rankin, D. J.;Jiang, J.;

Apparue dans: IEEE Transactions on Nuclear Science

Date publication: 04.-2011, volume: 58, issue:2, pages: 468 - 478

Editeur: IEEE

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» A High Current Accuracy Boost White LED Driver Based on Offset Calibration Technique

Résumé:
The current accuracy and power efficiency of a boost white light-emitting-diode (WLED) driver are usually design tradeoffs since the power efficiency is inversely proportional to the reference voltage, whereas the current accuracy is proportional to the reference voltage. Traditionally, a boost WLED driver with high current accuracy and high power efficiency demand a large chip area because mismatch decreases with increasing size. This paper proposes an offset calibration technique to improve both current accuracy and power efficiency while keeping the chip area relatively small. An overvoltage protection (OVP) circuit and an overcurrent protection (OCP) circuit prevent the proposed driver from being damaged due to WLED failure. The design is fabricated in a Taiwan Semiconductor Manufacturing Company 0.25-\\mu{m} 60-V bipolar–CMOS–double-diffused-MOS process. The measurement results show that the current variation is less than 1% when the input voltage and the number of loaded WLEDs are varied in a wide range. The maximum power conversion efficiency is 86.7% at a 5-V input with four loaded WLEDs. The OVP is 58 V, and the OCP is 2 A.

Auteurs: Hsieh, Y.-T.;Liu, B.-D.;Wu, J.-F.;Fang, C.-L.;Tsai, H.-H.;Juang, Y.-Z.;

Apparue dans: IEEE Transactions on Circuits and Systems II: Express Briefs

Date publication: 04.-2011, volume: 58, issue:4, pages: 244 - 248

Editeur: IEEE

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» A high frequency sensor for optical beam deflection atomic force microscopy

Résumé:
We demonstrate a novel electronic readout for quadrant photodiode based optical beam deflection setups. In our readout, the signals used to calculate the deflections remain as currents, instead of undergoing an immediate conversion to voltages. Bipolar current mirrors are used to perform all mathematical operations at the transistor level, including the signal normalizing division. This method has numerous advantages, leading to significantly simpler designs that avoid large voltage swings and parasitic capacitances. The bandwidth of our readout is solely limited by the capacitance of the quadrant photodiode junctions, making the effective bandwidth a function of the intensity of photocurrents and thus the applied power of the beam deflection laser. Using commercially available components and laser intensities of 1–4 mW we achieved a 3 dB bandwidth of 20 MHz with deflection sensitivities of up to 0.5–1 V/nm and deflection noise levels below 4.5

fm/

√

. Atomic resolution imaging of muscovite mica using FM–AFM in water demonstrates the sensitivity of this novel readout.

Auteurs: Enning, Raoul;Ziegler, Dominik;Nievergelt, Adrian;Friedlos, Ralph;Venkataramani, Krithika;Stemmer, Andreas;

Apparue dans: Review of Scientific Instruments

Date publication: 04.-2011, volume: 82, issue:4, pages: 043705 - 043705-6

Editeur: IEEE

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» A High-IIP3 Third-Order Elliptic Filter With Current-Efficient Feedforward-Compensated Opamps

Résumé:
A low-distortion active filter is realized using current-efficient feedforward-compensated operational amplifiers in the integrators and feedforward current injection in the summing amplifier. A third-order elliptic low-pass filter with two possible bandwidth settings of 17 and 8.5 MHz consumes 1.8 mW from a 1.8-V supply and occupies 0.17 \{mm}^{2} in a 0.18- \\mu{m} CMOS process. The measured maximum signal-to-noise and distortion ratios at the two bandwidth settings are 50.5 and 52.5 dB, respectively. The corresponding third-order intermodulation intercept points (IIP3) are +28.2 and +30.8 dBm. Automatic tuning is used at the startup to counter process variations and set the bandwidth accurately.

Auteurs: Krishnapura, N.;Agrawal, A.;Singh, S.;

Apparue dans: IEEE Transactions on Circuits and Systems II: Express Briefs

Date publication: 04.-2011, volume: 58, issue:4, pages: 205 - 209

Editeur: IEEE

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» A high-pressure atomic force microscope for imaging in supercritical carbon dioxide

Résumé:
A high-pressure atomic force microscope (AFM) that enables in situ, atomic scale measurements of topography of solid surfaces in contact with supercritical CO₂ (scCO₂) fluids has been developed. This apparatus overcomes the pressure limitations of the hydrothermal AFM and is designed to handle pressures up to 100 atm at temperatures up to ∼350 K. A standard optically-based cantilever deflection detection system was chosen. When imaging in compressible supercritical fluids such as scCO₂, precise control of pressure and temperature in the fluid cell is the primary technical challenge. Noise levels and imaging resolution depend on minimization of fluid density fluctuations that change the fluid refractive index and hence the laser path. We demonstrate with our apparatus in situ atomic scale imaging of a calcite (CaCO₃) mineral surface in scCO₂; both single, monatomic steps and dynamic processes occurring on the (1014) surface are presented. This new AFM provides unprecedented in situ access to interfacial phenomena at solid–fluid interfaces under pressure.

Auteurs: Lea, A. S.;Higgins, S. R.;Knauss, K. G.;Rosso, K. M.;

Apparue dans: Review of Scientific Instruments

Date publication: 04.-2011, volume: 82, issue:4, pages: 043709 - 043709-7

Editeur: IEEE

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» A High-Temperature Superconducting Notch Filter to Suppress Cellular-Band Interference in Radiotelescopes

Résumé:
An experimental high-temperature superconducting four-pole filter for mitigation of the IMT 2000 cellular band in radiotelescopes is presented. The filter uses a novel capacitive cross-coupling to achieve a quasi-elliptic response. Composite right/left-handed (CRLH) zeroth-order resonators are used to avoid harmonic generation throughout the UHF and L-bands.

Auteurs: Corona-Chavez, A.;Nogues-Hoyos, M.;Esteras-Otal, L.;Murthy, D. V. B.;Sanchez-Rinza, B.;

Apparue dans: IEEE Transactions on Applied Superconductivity

Date publication: 04.-2011, volume: 21, issue:2, pages: 68 - 70

Editeur: IEEE

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» A High-Throughput LDPC Decoder Architecture With Rate Compatibility

Résumé:
This paper presents a high-throughput decoder architecture for rate-compatible (RC) low-density parity-check (LDPC) codes which supports arbitrary code rates between the rate of mother code and 1. Puncturing techniques are applied to produce different rates for quasi-cyclic (QC) LDPC codes with dual-diagonal parity structure. Simulation results show that our selected puncturing scheme only introduces the BER performance degradation of less than 0.2 dB, compared with the dedicated codes for different rates specified in the IEEE 802.16e (WiMax) standard. Subsequently, parallel layered decoding architecture (PLDA) is employed for high-throughput decoder design. While the original PLDA is lack of rate flexibility, the problem is solved gracefully by incorporating the puncturing scheme. As a case study, an RC-LDPC decoder based on the rate-1/2 WiMax LDPC code is implemented in the CMOS 65-nm process. The clock frequency is 1.1 GHz, and the synthesis core area is 1.96 mm^{2}. The decoder can achieve an input throughput of 1.28 Gb/s at ten iterations and supports any rate between 1/2 and 1.

Auteurs: Zhang, K.;Huang, X.;Wang, Z.;

Apparue dans: IEEE Transactions on Circuits and Systems I: Regular Papers

Date publication: 04.-2011, volume: 58, issue:4, pages: 839 - 847

Editeur: IEEE

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» A Highly Punchthrough-Immune Array Architecture and Program Method for Floating-Gate NOR-Type Nonvolatile Memory

Résumé:
A novel array architecture is proposed for floatinggate nor-type nonvolatile memory cells. By embedding a floating \{n}+ region between two cells in each memory pair, punchthrough (PT) immunity is greatly improved. Since the operating cell and the cascade cell belong to two independent wordlines, bit-pattern effect on read and program characteristics is mitigated, and multilevel-cell storage can be easily realized. No additional program disturb has been found. Erase, endurance, and retention characteristics are comparable with its conventional counterpart. According to simulations, L_{g} as short as 56 nm, which is projected to serve for 28 nm technology node, is feasible without suffering a serious PT effect.

Auteurs: Tsai, W.-J.;Ou, T. F.;Cheng, C. H.;Lu, C.-Y.;Huang, J. S.;Yan, S. G.;Cheng, C. C.;Tsai, Ping Hung;Hung, C. S.;Chu, T. K.;Yih, C. M.;Lu, T. C.;Chen, K. C.;Lu, C.-Y.;

Apparue dans: IEEE Transactions on Electron Devices

Date publication: 04.-2011, volume: 58, issue:4, pages: 945 - 952

Editeur: IEEE

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» A Hybrid Approach for Radio Resource Management in Heterogeneous Cognitive Networks

Résumé:
Distributing Radio Resource Management (RRM) in heterogeneous wireless networks is an important research and development axis that aims at reducing network complexity. In this context, RRM decision making can be delegated to mobiles by incorporating cognitive capabilities into mobile handsets, resulting in the reduction of signalling and processing burden. This may however result in inefficiencies (such as those known as the "tragedy of commons") that are inherent to equilibria in non-cooperative games. Due to the concern for efficiency, centralized network architectures and protocols keep being considered and being compared to decentralized ones. From the point of view of the network architecture, this implies the co-existence of network-centric and terminal-centric RRM schemes. Instead of taking part within the debate among the supporters of each solution, we propose in this paper hybrid schemes where the wireless users are assisted in their decisions by the network that broadcasts aggregated load information. At some system's states, the network manager may impose his decisions on the network users. In other states the mobiles may take autonomous actions in reaction to information sent by the network. In order to improve the performance of the non-cooperative scenario, we investigate the properties of an alternative solution concept named Stackelberg game, in which the network tries to control the users' behavior by broadcasting appropriate information, expected to maximize its utility, while individual users maximize their own utility. We derive analytically the utilities related to the Quality of Service (QoS) perceived by mobile users and develop a Bayesian framework to obtain the equilibria. Numerical results illustrate the advantages of using our hybrid game framework in an association problem in a network composed of HSDPA and 3G LTE system that serve streaming and elastic flows.

Auteurs: Haddad, M.;Elayoubi, S.E.;Altman, E.;Altman, Z.;

Apparue dans: IEEE Journal on Selected Areas in Communications

Date publication: 04.-2011, volume: 29, issue:4, pages: 831 - 842

Editeur: IEEE

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» A Hybrid Field-Harmonics Approach for Passive Shimming Design in MRI

Résumé:
This paper presents a new passive shimming (PS) design scheme for the correction of static magnetic-field inhomogeneities in magnetic resonance imaging (MRI) systems. In MRI, the PS procedure usually employs magnetic-field-based or harmonic-based methods to find an optimal iron-piece configuration to improve the uniformity of the static magnetic field in the imaging region. For the field-based PS technique, the peak-to-peak field inhomogeneity is minimized, and the harmonic components are inherently unconstrained; in the harmonic-based scheme, selected unwanted harmonics are minimized, and the overall field uniformity is consequently reduced. The field approach usually provides good field homogeneity but lacks flexibility in managing all terms of spherical harmonic field expansion; the harmonic approach is capable of controlling targeted low-order harmonic terms but can have difficulty in producing optimal overall field homogeneity and in controlling high-order harmonics. The new algorithm proposed herein attempts to combine the strengths of these two methods for a better PS solution. During the PS implementation, an explicit expression of the system matrix with both the field and harmonic sensitivities is generated, and then, an optimization procedure is performed for the determination of shim-piece thicknesses and locations. A case study presented shows that the hybrid method provides good quality, flexible solutions for controlling individual harmonic impurities, and also overall field uniformity. This method is not only applicable to conventional MRI magnets, but also, its flexibility means that it can be easily used to shim unconventional electromagnets.

Auteurs: Liu, F.;Zhu, J.;Xia, L.;Crozier, S.;

Apparue dans: IEEE Transactions on Applied Superconductivity

Date publication: 04.-2011, volume: 21, issue:2, pages: 60 - 67

Editeur: IEEE

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» A Hybrid System-Level Modeling and Simulation Methodology for Structurally Complex Microelectromechanical Systems

Résumé:
We present a hybrid system-level modeling and simulation methodology by combining numerical macromodels with parameterized lumped-element behavioral models for structurally complex microelectromechanical systems (MEMS). We decompose the MEMS into several functional components. For those components with complex geometry and boundary conditions, we model them using numerical macromodels, whereas for those with simple geometry, we model them using parameterized lumped-element behavioral models. Both models are represented by the same syntax and similar equation forms to ensure the compatibility. Afterward, the hybrid numerical macromodels and parameterized behavioral models are inserted into the same simulator and then interconnected to each other according to the original topography of the MEMS for system-level simulation. As one of the key technologies of the proposed methodology, macromodeling has been improved in two aspects. First, macromodeling for the component with dynamic boundary condition is achieved by combining modal analysis with a novel iterated improved reduced system method. Second, angular parameterization for the components with the same geometry but different initial orientation is achieved by the matrix coordinate transformation. A z-axis micromachined gyroscope is used to demonstrate the proposed methodology. Simulation results show that the method can efficiently support the design for structurally complex MEMS. hfill[2010-0007]

Auteurs: Xu, J.;Yuan, W.;Xie, J.;Chang, H.;Ma, B.;

Apparue dans: Journal of Microelectromechanical Systems

Date publication: 04.-2011, volume: 20, issue:2, pages: 538 - 548

Editeur: IEEE

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» A Hyperelastic Finite-Element Model of Human Skin for Interactive Real-Time Surgical Simulation

Résumé:
A finite-element (FE) model of human skin is proposed for future use in an interactive real-time surgical simulation to teach surgeons procedures, such as facial reconstruction using skin-flap repair. For this procedure, skin is cut into flaps that are stretched to cover openings in the face. Thus, the model must recreate the visual, haptic, and force feedback expected by the surgeon. To develop the FE model, a series of in vitro experiments were conducted on samples of human skin, subjected to uniaxial and planar tensile straining. Reduced polynomial hyperelastic (HE) materials were found to fit many of the samples’ stress–strain data well. Finally, an explicit dynamic FE mesh was developed based on the fitted HE material models. A total Lagrangian formulation with the half-step central difference method was employed to integrate the dynamic equation of motion of the mesh. The mesh was integrated into two versions of a real-time skin simulator: a single-threaded version running on a computer’s main central processing unit and a multithreaded version running on the computer’s graphics card. The latter was achieved by exploiting recent advances in programmable graphics technology.

Auteurs: Lapeer, R. J.;Gasson, P. D.;Karri, V.;

Apparue dans: IEEE Transactions on Biomedical Engineering

Date publication: 04.-2011, volume: 58, issue:4, pages: 1013 - 1022

Editeur: IEEE

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» A K-Band Low-Power Colpitts VCO With Voltage-to-Current Positive-Feedback Network in 0.18 \\mu{\rm m} CMOS

Résumé:
A circuit topology suitable for low-power Colpitts voltage-controlled oscillators (VCOs) is presented in this letter. By employing the proposed voltage-to-current positive-feedback network, the required transconductance for VCO startup can be reduced, leading to the minimized dc power for sustaining VCO oscillation. Moreover, the {rm Q}-factor enhanced varactor is used in this VCO design for phase noise improvement. Based on the proposed architecture, the fabricated VCO in standard 0.18 \mu{rm m} CMOS exhibits a 3.58% tuning range. Operating at 1.35-V supply voltage, the VCO core consumes 3.3-mW dc power. The measured phase noise is -110.82 \\sim {rm dBc}/{rm Hz} at 1 MHz offset from 18.95 GHz oscillation frequency. Compared with the recently published K-band 0.18 \mu{rm m} CMOS VCOs, it is observed that the proposed Colpitts VCO exhibits comparable circuit performance under low dc-power consumption.

Auteurs: Wang, T.-P.;

Apparue dans: IEEE Microwave and Wireless Components Letters

Date publication: 04.-2011, volume: 21, issue:4, pages: 218 - 220

Editeur: IEEE

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» A K-Band Low-Power Colpitts VCO With Voltage-to-Current Positive-Feedback Network in 0.18 \\mu{\rm m} CMOS

Résumé:
A circuit topology suitable for low-power Colpitts voltage-controlled oscillators (VCOs) is presented in this letter. By employing the proposed voltage-to-current positive-feedback network, the required transconductance for VCO startup can be reduced, leading to the minimized dc power for sustaining VCO oscillation. Moreover, the Q-factor enhanced varactor is used in this VCO design for phase noise improvement. Based on the proposed architecture, the fabricated VCO in standard 0.18 μm CMOS exhibits a 3.58% tuning range. Operating at 1.35-V supply voltage, the VCO core consumes 3.3-mW dc power. The measured phase noise is -110.82 dBc/Hz at 1 MHz offset from 18.95 GHz oscillation frequency. Compared with the recently published K-band 0.18 μm CMOS VCOs, it is observed that the proposed Colpitts VCO exhibits comparable circuit performance under low dc-power consumption.

Auteurs: To-Po Wang;

Apparue dans: IEEE Microwave and Wireless Components Letters

Date publication: 04.-2011, volume: 21, issue:4, pages: 218 - 220

Editeur: IEEE

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» A Lab-Scale Experiment to Measure Terminal Velocity of Volcanic Ash

Résumé:
In this paper, a novel methodology to measure trajectory and terminal velocity of volcanic ash in laboratory is presented. The methodology consists of the following: (1) planning a lab-scale experiment in order to reproduce the sedimentation processes of fine volcanic ash based on the principle of dynamic similarity; (2) realizing the experimental setup using a glass tank filled with glycerine, a webcam-based vision system and a dedicated image postprocessing tool able to estimate the position and the terminal velocity of any particle falling in the tank; (3) performing a calibration procedure to accurately estimate the uncertainty on particle velocity; and (4) comparing the experimental results with estimations obtained by some particle fallout models available in literature. Our results show that there is a good agreement between experimental terminal velocities and those obtained applying a model which includes information on particle shape. The proposed methodology allows us to investigate how the particle shape affects the sedimentation processes. Since the latter is strategic to improve the accuracy on modeling ash fallout, this work will contribute to reduce risks to aviations during explosive eruptions.

Auteurs: Andò, B.;Coltelli, M.;Prestifilippo, M.;Scollo, S.;

Apparue dans: IEEE Transactions on Instrumentation and Measurement

Date publication: 04.-2011, volume: 60, issue:4, pages: 1340 - 1347

Editeur: IEEE

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» A Large \sigma V_{\rm TH}/VDD Tolerant Zigzag 8T SRAM With Area-Efficient Decoupled Differential Sensing and Fast Write-Back Scheme

Résumé:
Nanometer SRAM cannot achieve lower VDDmin due to read-disturb, half-select disturb and write failure. This paper demonstrates quantitative performance advantages of a zigzag 8T-SRAM (Z8T) cell over the decoupled single-ended sensing 8T-SRAM (DS8T) with write-back schemes, which was previously recognized as the most area-efficient cell under large σV_TH/VDD conditions. Since Z8T uses only 1T for each decoupled read-port, faster 2T differential sensing (D²S) can be implemented within the same area as the single-ended DS8T. Thanks to D²S, Z8T cell enables much faster R/W speed at VDDmin than DS8T. For the same VDDmin/speed, Z8T reduces the cell area by 15%. The Z8T 32 Kb macro is 14% smaller area and 53% faster than DS8T cells. Three macros were fabricated using foundry provided 65 nm low-power and 90 nm generic processes. The measured VDDmin for a 65 nm 256-row 32 Kb and a 32-row 4 Kb macro are 430 mV and 250 mV respectively. The measured VDDmin for a 90 nm 256-row 64 Kb macro is 230 mV.

Auteurs: Jui-Jen Wu;Yen-Huei Chen;Meng-Fan Chang;Po-Wei Chou;Chien-Yuan Chen;Hung-Jen Liao;Ming-Bin Chen;Yuan-Hua Chu;Wen-Chin Wu;Yamauchi, H.;

Apparue dans: IEEE Journal of Solid-State Circuits

Date publication: 04.-2011, volume: 46, issue:4, pages: 815 - 827

Editeur: IEEE

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» A layered microchip conductance detector with through-layer access to detection fields and high sensitivity to dielectric constant

Résumé:
The present study explores a novel apertured microchip conductance detector (AMCD) that is sensitive to dielectric constant. Fashioned on silicon oxide/silicon using optical microlithography, the detector has novel parallel-plate geometry with a top mesh electrode, a middle apertured insulator, and a bottom conducting electrode. This monolithic apertured architecture is planar and may be provided with a thin insulator layer enabling large capacitances, while the top mesh electrode and middle apertured-insulator enable access to regions of the capacitor where electric fields are strong. Hence, the detector is sensitive yet mechanically robust. To test its response, the AMCD was immersed in various solvents, namely water, methanol, acetonitrile, and hexanes. Its response was found to vary in proportion to the solvents’ respective dielectric constants. The AMCD was also able to distinguish quantitatively the presence of various molecules in solution, including molecules with chromophores [such as acetylsalicylic acid (ASA)] in methanol and those without chrompohores [such as polyethylene glycol 200 Daltons (PEG200)] in methanol or water. The universal nature of dielectric constant and the microchip detector's sensitivity point to a wide range of potential applications.

Auteurs: Suganuma, Y.;Dhirani, A.-A.;

Apparue dans: Review of Scientific Instruments

Date publication: 04.-2011, volume: 82, issue:4, pages: 044701 - 044701-4

Editeur: IEEE

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» A Less Conservative LMI Condition for Robust {cal D}-Stability of Polynomial Matrix Polytopes—A Projection Approach

Résumé:
This technical note investigates the problem of checking robust {cal D}-stability of a polytope of polynomial matrices. Finsler's projection lemma is taken to derive a new sufficient condition in terms of a linear matrix inequality (LMI) feasibility problem. The basic idea behind this condition is to lift the existing stability condition into the one of larger space by means of Finsler's lemma and, based on it, to introduce additional decision variables. Examples are given to show that the proposed condition can yield less conservative results than the previous one.

Auteurs: Lee, D. H.;Park, J. B.;Joo, Y. H.;

Apparue dans: IEEE Transactions on Automatic Control

Date publication: 04.-2011, volume: 56, issue:4, pages: 868 - 873

Editeur: IEEE

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» A Link Analysis Extension of Correspondence Analysis for Mining Relational Databases

Résumé:
This work introduces a link analysis procedure for discovering relationships in a relational database or a graph, generalizing both simple and multiple correspondence analysis. It is based on a random walk model through the database defining a Markov chain having as many states as elements in the database. Suppose we are interested in analyzing the relationships between some elements (or records) contained in two different tables of the relational database. To this end, in a first step, a reduced, much smaller, Markov chain containing only the elements of interest and preserving the main characteristics of the initial chain, is extracted by stochastic complementation. This reduced chain is then analyzed by projecting jointly the elements of interest in the diffusion map subspace and visualizing the results. This two-step procedure reduces to simple correspondence analysis when only two tables are defined, and to multiple correspondence analysis when the database takes the form of a simple star-schema. On the other hand, a kernel version of the diffusion map distance, generalizing the basic diffusion map distance to directed graphs, is also introduced and the links with spectral clustering are discussed. Several data sets are analyzed by using the proposed methodology, showing the usefulness of the technique for extracting relationships in relational databases or graphs.

Auteurs: Luh Yen;Saerens, M.;Fouss, F.;

Apparue dans: IEEE Transactions on Knowledge and Data Engineering

Date publication: 04.-2011, volume: 23, issue:4, pages: 481 - 495

Editeur: IEEE

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» A Little More, a Lot Better: Improving Path Quality by a Path-Merging Algorithm

Résumé:
Sampling-based motion planners are an effective means to generate collision-free motion paths. However, the quality of these motion paths (with respect to quality measures, such as path length, clearance, smoothness, or energy) is often notoriously low, especially in high-dimensional configuration spaces. We introduce a simple algorithm to merge an arbitrary number of input motion paths into a hybrid output path of superior quality, for a broad and general formulation of path quality. Our approach is based on the observation that the quality of certain subpaths within each solution may be higher than the quality of the entire path. A dynamic-programming algorithm, which we recently developed to compare and cluster multiple motion paths, reduces the running time of the merging algorithm significantly. We tested our algorithm in motion-planning problems with up to 12 degrees of freedom (DOFs), where our method is shown to be particularly effective. We show that our algorithm is able to merge a handful of input paths produced by several different motion planners to produce output paths of much higher quality.

Auteurs: Raveh, B.;Enosh, A.;Halperin, D.;

Apparue dans: IEEE Transactions on Robotics

Date publication: 04.-2011, volume: 27, issue:2, pages: 365 - 371

Editeur: IEEE

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» A Low Energy Injection-Locked FSK Transceiver With Frequency-to-Amplitude Conversion for Body Sensor Applications

Résumé:
An energy-efficient 920 MHz FSK transceiver for wireless body sensor network (BSN) applications is implemented in 0.18 μm CMOS technology with 0.7 V supply. A transceiver architecture based on injection-locked frequency divider (ILFD) is proposed for the low energy consumption. In the receiver, the ILFD in the signal path converts the received FSK signal to amplitude-modulated signal which is applied to the next envelope detector. In the transmitter, the ILFD is used as digitally-controlled oscillator (DCO) which directly modulates the FSK signal with digital data. The DCO replaces the frequency synthesizer to eliminate the crystal oscillator (XO), which leads to reduce power consumption and cost. The transceiver can detect whether injection locking occurs or not, and calibrates the frequency drift of DCO over temperature variation thanks to ILFD based architecture. The receiver and transmitter consume 420 μW and 700 μW , respectively, at - 10 dBm output power with a data rate of 5 Mb/s, corresponding to energy consumption of 84 pJ per received bit and 140 pJ per transmitted bit.

Auteurs: Joonsung Bae;Long Yan;Hoi-Jun Yoo;

Apparue dans: IEEE Journal of Solid-State Circuits

Date publication: 04.-2011, volume: 46, issue:4, pages: 928 - 937

Editeur: IEEE

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» A Low Power and Wide Range Programmable Clock Generator With a High Multiplication Factor

Résumé:
A programmable delay locked loop (DLL) based clock generator, providing a high multiplication factor, has been developed in a 0.18-\mum CMOS technology. Utilizing the proposed pulse generator, purely consisting of D flip flops (DFFs) and inverters, the clock generator provides a high multiplication factor of up to 24. It consumes only 16.2 mW when generating 2.16 GHz output signals. In addition, the proposed saturated-type unit delay cell adopted in the voltage controlled delay line (VCDL) is capable of providing a long delay while maintaining fast-switching signal edges. Thus, the DLL can lock up an input reference frequency as low as 30 MHz while maintaining good phase noise performance and small chip area occupancy. The phase noise is -88.7 and -99.8 dBc/Hz at 10 kHz and 100 kHz offsets, respectively, from the operating frequency of 1.2 GHz, which is equivalent to a 1.7 ps RMS jitter. The active chip area takes only 0.051 mm^{2}.

Auteurs: Choi, J.;Kim, S. T.;Kim, W.;Kim, K.-W.;Lim, K.;Laskar, J.;

Apparue dans: IEEE Transactions on Very Large Scale Integration Systems

Date publication: 04.-2011, volume: 19, issue:4, pages: 701 - 705

Editeur: IEEE

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» A Low-Complexity PAPR Reduction Scheme for OFDMA Uplink Systems

Résumé:
Selected mapping (SLM) schemes are commonly employed to reduce the peak-to-average power ratio (PAPR) in orthogonal frequency division multiplexing (OFDM) systems. To decrease the number of inverse fast Fourier transform (IFFT) operations in traditional SLM schemes, the candidate signals can be generated in the time domain by linearly combining the original time-domain transmitted signal with multiple cyclic shift equivalents. However, the weighting coefficients and the number of cyclic shifts should be properly chosen to ensure that the elements of the corresponding frequency domain phase rotation vectors have an equal magnitude. This study presents a number of expressions for meeting this equal-gain-magnitude constraint in orthogonal frequency division multiple access (OFDMA) uplink systems. Of these various solutions, a low-complexity expression is selected to construct the proposed low-complexity scheme that requires only one IFFT. The proposed architecture is proven to be applicable to OFDMA uplink systems using either an interleaved or a sub-band sub-carrier assignment strategy.

Auteurs: Wang, Sen-Hung;Sie, Jia-Cheng;Li, Chih-Peng;Chen, Yung-Fang;

Apparue dans: IEEE Transactions on Wireless Communications

Date publication: 04.-2011, volume: 10, issue:4, pages: 1242 - 1251

Editeur: IEEE

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» A Low-Dispersion Realization of Precise Integration Time-Domain Method Using a Fourth-Order Accurate Finite Difference Scheme

Résumé:
A modified precise integration time-domain (PITD) method, called PITD(4) algorithm, is presented in order to mitigate the numerical dispersion errors of a recently proposed PITD method. The PITD(4) method is based on both the fourth-order accurate finite-difference scheme and the precise integration technique. Both the stability condition and the numerical dispersion relations of the PITD(4) method are derived analytically and the effects of spatial and time steps on the numerical dispersion are investigated in detail. It is found that with the precise integration technique, the stability condition of the PITD(4) method is much larger than the Courant-Friedrich-levy (CFL) stability condition of the conventional finite difference time domain; with the fourth-order accurate finite-difference scheme, the numerical dispersion errors of the PITD(4) method are much less than that of the PITD methods. Numerical examples are presented to validate the accuracy and the effectiveness of the PITD(4) method, and to verify our analysis of the numerical dispersion characteristics of the PITD(4) method.

Auteurs: Bai, Z.-M.;Ma, X.-K.;Sun, G.;

Apparue dans: IEEE Transactions on Antennas and Propagation

Date publication: 04.-2011, volume: 59, issue:4, pages: 1311 - 1320

Editeur: IEEE

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» A Low-Overhead Asynchronous Interconnection Network for GALS Chip Multiprocessors

Résumé:
A new asynchronous interconnection network is introduced for globally-asynchronous locally-synchronous (GALS) chip multiprocessors. The network eliminates the need for global clock distribution, and can interface multiple synchronous timing domains operating at unrelated clock rates. In particular, two new highly-concurrent asynchronous components are introduced which provide simple routing and arbitration/merge functions. Post-layout simulations in identical commercial 90 nm technology indicate that comparable recent synchronous router nodes have 5.6–10.7\times more energy per packet and 2.8–6.4\times greater area than the new asynchronous nodes. Under random traffic, the network provides significantly lower latency and identical throughput over the entire operating range of the 800 MHz network and through mid-range traffic rates for the 1.36 GHz network, but with degradation at higher traffic rates. Preliminary evaluations are also presented for a mixed-timing (GALS) network in a shared-memory parallel architecture, running both random traffic and parallel benchmark kernels, as well as directions for further improvement.

Auteurs: Horak, M. N.;Nowick, S. M.;Carlberg, M.;Vishkin, U.;

Apparue dans: IEEE Transactions on Computer-Aided Design of Integrated Circuits and Systems

Date publication: 04.-2011, volume: 30, issue:4, pages: 494 - 507

Editeur: IEEE

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» A Macro Finite-Element Formulation for Cardiac Electrophysiology Simulations Using Hybrid Unstructured Grids

Résumé:
Electrical activity in cardiac tissue can be described by the bidomain equations whose solution for large-scale simulations still remains a computational challenge. Therefore, improvements in the discrete formulation of the problem, which decrease computational and/or memory demands are highly desirable. In this study, we propose a novel technique for computing shape functions of finite elements (FEs). The technique generates macro FEs (MFEs) based on the local decomposition of elements into tetrahedral subelements with linear shape functions. Such an approach necessitates the direct use of hybrid meshes (HMs) composed of different types of elements. MFEs are compared to classic standard FEs with respect to accuracy and RAM memory usage under different scenarios of cardiac modeling, including bidomain and monodomain simulations in 2-D and 3-D for simple and complex tissue geometries. In problems with analytical solutions, MFEs displayed the same numerical accuracy of standard linear triangular and tetrahedral elements. In propagation simulations, conduction velocity and activation times agreed very well with those computed with standard FEs. However, MFEs offer a significant decrease in memory requirements. We conclude that HMs composed of MFEs are well suited for solving problems in cardiac computational electrophysiology.

Auteurs: Rocha, B. M.;Kickinger, F.;Prassl, A. J.;Haase, G.;Vigmond, E. J.;Santos , R. W. d.;Zaglmayr, S.;Plank, G. P.;

Apparue dans: IEEE Transactions on Biomedical Engineering

Date publication: 04.-2011, volume: 58, issue:4, pages: 1055 - 1065

Editeur: IEEE

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» A magnetoelectric, broadband vibration-powered generator for intelligent sensor systems

Résumé:
Magnetoelectric (ME) transducers were originally intended for magnetic field sensors but have recently been used in vibration energy harvesting. In order for vibration energy harvesters to be effective over a range of vibration frequencies, recently many technologies have been investigated to broaden the frequency range of the harvesters using piezoelectric, electromagnetic and electrostatic transductions, but few have been studied that use ME transducers. This paper presents a new broadband vibration energy harvester using ME transducer, which takes advantage of multi-cantilever beams and nonlinear behavior of the magnetic force to expand the working bandwidth in ambient low frequency vibration. And a...

Auteurs: Jin, Yang , Yumei, Wen , Ping, Li , Xianzhi, Dai

Apparue dans: Sensors and Actuators A: Physical

Date publication: 04.-2011

Editeur: Elsevier B.V.

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» A Markov model for indoor ultra-wideband channel with people shadowing and channel fading statistics

Résumé:
For an indoor UWB communication system, the line-of-sight (LOS) path between the transmitter and receiver may be frequently blocked by mobility. Blocking of LOS path may significantly affect the quality of service of on-going UWB communications. Moreover, fading will also be present in the communication channel. Based on the Angular Power Spectrum Density (APSD) and human blocking model, a packet-level UWB channel model is built considering the shadowing and the fading processes based on a Finite-state Markov Chain (FSMC) and the performance of the channel is analyzed for four fading distributions: Rayleigh, Rician, Weibull and Nakagami fading distributions.

Auteurs: P., Anita Devi , Vidhyacharan, Bhaskar

Apparue dans: Digital Signal Processing

Date publication: 04.-2011

Editeur: Elsevier B.V.

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» A Mathematical Model and Error Analysis of Coriolis Mass Flowmeters

Résumé:
Manufacturers empirically made Coriolis mass flowmeters (CMFs) for more than 25 years, prior to formulation of a comprehensive, fundamental theory. In this paper, we analytically develop a general model of CMFs that supports the designs of the flowmeters and are referenced for their improvement, as well as their production method. We first make a model that fully explains CMFs with twin U-shaped flow tubes. Then, we discuss its general application to CMFs that use different arrangements of flow tubes, e.g., a single tube or straight tubes. We further explain, by using the developed model, errors in the measurement caused by external vibration, errors by temperature and process pressure, and their error correction.

Auteurs: Kazahaya, M.;

Apparue dans: IEEE Transactions on Instrumentation and Measurement

Date publication: 04.-2011, volume: 60, issue:4, pages: 1163 - 1174

Editeur: IEEE

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» A Maximum Principle for Single-Input Boolean Control Networks

Résumé:
Boolean networks have recently been attracting considerable interest as computational models for genetic and cellular networks. We consider a Mayer-type optimal control problem for a single-input Boolean network, and derive a necessary condition for a control to be optimal. This provides an analog of Pontryagin's maximum principle for single-input Boolean networks.

Auteurs: Laschov, D.;Margaliot, M.;

Apparue dans: IEEE Transactions on Automatic Control

Date publication: 04.-2011, volume: 56, issue:4, pages: 913 - 917

Editeur: IEEE

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» A measurement setup for acquiring the local magnetic properties of plastically deformed soft magnetic materials

Résumé:
This paper introduces a new measurement setup for extraction of the local magnetic properties. With the help of finite element method simulations, modifications are made on the previous double-C-yoke method. Small dimension measuring coils are applied in the stray field produced by the magnetic circuit to evaluate the local magnetic properties of the specified part of the specimen. Through the measurements with the plastically deformed materials at different temperatures, it indicates that the magnetic properties of soft magnetic materials are quite sensitive to plastic straining. After high-temperature thermal treatment on the plastically deformed specimen, the local magnetic properties exhibit an obvious recovery.

Auteurs: Bi, Shasha;Sutor, Alexander;Lerch, Reinhard;Xiao, Yunshi;

Apparue dans: Journal of Applied Physics

Date publication: 04.-2011, volume: 109, issue:7, pages: 07E306 - 07E306-3

Editeur: IEEE

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» A Message-Passing Approach to Distributed Resource Allocation in Uplink DFT-Spread-OFDMA Systems

Résumé:
In this paper, we consider the problem of resource allocation in the DFT-Spread-OFDMA (DFT-S-OFDMA) uplink. We show that the resource allocation problem can be formulated as a set packing problem, which in general is NP-hard. We propose polynomial-time message-passing based algorithms, one of which is guaranteed to yield a solution that is within a constant fraction of the optimal solution and is also asymptotically optimal in the limit as the number of subcarriers in the system goes to infinity. The message-passing based algorithm is also extended to solve the resource allocation problem over a multi-cell uplink in a distributed fashion. Our algorithms account for finite input alphabets and non-ideal practical outer codes. Extensive simulations are performed to assess the performance of the proposed algorithms and it is shown that they yield near-optimal solutions at a low complexity and with a low memory requirement.

Auteurs: Yang, Kai;Prasad, Narayan;Wang, Xiaodong;

Apparue dans: IEEE Transactions on Communications

Date publication: 04.-2011, volume: 59, issue:4, pages: 1099 - 1113

Editeur: IEEE

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» A method for determining the characteristic impedance of transmission lines embedded in transitions

Résumé:
This paper presents a method for determining the characteristic impedance (ZL) of transmission lines embedded in transitions. This method is based on two properties: (1) a reliable method for calculating the propagation constant (?) of reflecting lines, and (2) the calculation of the S11 parameter of each transition employed for this kind of transmission lines. For calculating the characteristic impedance of these lines, the proposed method uses measurements of two transmission lines with different lengths.

Auteurs: Marco A., Panduro , Aldo, Mendez

Apparue dans: AEU - International Journal of Electronics and Communications

Date publication: 04.-2011

Editeur: Elsevier B.V.

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» A method for measuring exchange stiffness in ferromagnetic films

Résumé:
An exchange stiffness, Aex, in ferromagnetic films is obtained by fitting the M(H) dependence of two ferromagnetic layers antiferromagnetically coupled across a nonmagnetic spacer layer with a simple micromagnetic model. In epitaxial and textured structures this method allows measuring Aex between the crystallographic planes perpendicular to the growth direction of ferromagnetic films. Our results show that Aex between [0001] planes in textured Co grains is 1.54 ± 0.12 × 10^-11 J/m.

Auteurs: Girt, Erol;Huttema, W.;Mryasov, O. N.;Montoya, E.;Kardasz, B.;Eyrich, C.;Heinrich, B.;Dobin, A. Yu.;Karis, O.;

Apparue dans: Journal of Applied Physics

Date publication: 04.-2011, volume: 109, issue:7, pages: 07B765 - 07B765-3

Editeur: IEEE

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» A Method of Extracting Metal-Gate High-k Material Parameters Featuring Electron Gate Tunneling Current Transition

Résumé:
For metal-gate high-k dielectrics, there is a transition region in the electron gate tunneling current I_{g}, as characterized by a plot of \{dlnI}_{g}/\{dV}_{g} versus V_{g}. In this paper, we systematically construct a new fitting over the region, which can accurately determine material parameters, including metal work function, high- k electron affinity, and tunneling effective masses of electrons. First of all, a calculation of gate current due to electron direct tunneling and/or Fowler–Nordheim tunneling from an inversion layer is performed, yielding the guidelines of the fitting. Experimental samples are presented with n-channel metal–oxide–semiconductor field-effect transistors having low effective oxide thickness (1.4 nm) TaC/HfSiON/SiON gate stacks. Underlying material parameters are extracted accordingly and remain valid for higher temperature and gate voltage. We also demonstrate that a conventional method without a \{dlnI}_{g}/\{dV}_{g} fitting might lead to erroneous results. Thus, the \{dlnI}_{g}/\{dV}_{g} fitting is crucial to metal-gate high-k material parameter assessment.

Auteurs: Hsu, C.-Y.;Chang, H.-G.;Chen, M.-J.;

Apparue dans: IEEE Transactions on Electron Devices

Date publication: 04.-2011, volume: 58, issue:4, pages: 953 - 959

Editeur: IEEE

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» A Metric to Target Small-Delay Defects in Industrial Circuits

Résumé:
Timing-related defects are a major cause of test escapes and field returns for very deep-submicron (VDSM) integrated circuits. Small-delay variations induced by crosstalk, process variations, power supply noise, and resistive opens and shorts can cause timing failures in a design, leading to quality and reliability concerns. This article describes the authors' work with a previously proposed test-grading technique that uses output deviations for screening small-delay defects.

Auteurs: Yilmaz, M.;Tehranipoor, M.;Chakrabarty, K.;

Apparue dans: IEEE Design & Test of Computers

Date publication: 04.-2011, volume: 28, issue:2, pages: 52 - 61

Editeur: IEEE

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» A micro-optical modulation spectroscopy technique for local strain measurement

Résumé:
We provide a high throughput method of performing optical modulation spectroscopy, such as photoreflectance or other spectroscopy techniques which include photoluminescence on a micrometric resolution scale of the order of 10 μm. The spectroscopic technique is designed for strain induced by process in silicon wafers. The optical system is optimized using a polarizing beamsplitter in conjunction with a single Fresnel rhomb for the provision of an optimum separation of the reflected probe beam with minimal optical losses. In addition, a rapid detection system is used that allows the spectrum to be acquired within few seconds.

Auteurs: Chouaib, H.;Murtagh, M. E.;Kelly, P. V.;

Apparue dans: Review of Scientific Instruments

Date publication: 04.-2011, volume: 82, issue:4, pages: 043901 - 043901-6

Editeur: IEEE

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» A microbiological-based air cleaning system using a two-step process for removal of ammonia in discharge air from a pig rearing building

Résumé:
Highlights: ? A prototype of two-step air cleaning system using recycle water has been developed. ? It consists of a spray tower and a microbiological water purification unit (BWPU). ? Step 1: The spray tower removes ammonia in discharge air from a pig rearing building. ? Step 2: BWPU nitrifies ammonia and returns the water to the spray tower. ? Water pH remained <7.5, which enabled 55-95% ammonia removal efficiency.

Auteurs: In coming years large livestock farms will have to significantly reduce their emissions of odours, ammonia and dust to the surrounding area. The characteristics of a prototype air cleaning system for emission control in livestock buildings were measu

Apparue dans: Biosystems Engineering

Date publication: 04.-2011

Editeur: Elsevier B.V.

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» A Microphysics-Based Simulator for Advanced Airborne Weather Radar Development

Résumé:
Incorporating dual-polarized operation and microphysics-based processing is becoming a challenge to future scientific and commercial airborne weather radars. This paper introduces a Monte Carlo simulation-based approach to address the theoretical basis and uncertainties of hydrometeor scattering along with sensor platform properties. Detailed characterizations of mixed-phase aviation hydrometeor hazards (rain, snow, hail, and mixtures) and the impact of melting on polarimetric radar signature at X-band frequency are discussed. A “single resolution cell” Monte Carlo dual-polarization variable simulation technique is described and then applied in different radar scanning scenarios based on numeric weather prediction model output weather fields. The produced dual-polarization signatures of an X-band array radar for different scan scenarios are analyzed.

Auteurs: Zhengzheng Li;Yan Zhang;Guifu Zhang;Brewster, K.A.;

Apparue dans: IEEE Transactions on Geoscience and Remote Sensing

Date publication: 04.-2011, volume: 49, issue:4, pages: 1356 - 1373

Editeur: IEEE

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