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Electrical and Electronics Engineering publications abstract of: 07-2015 sorted by title, page: 0

» "Curiouser and Curiouser!"--The Fallout from Alice
Abstract:
The ramifications of last year's US Supreme Court decision in Alice Corp. v. CLS Bank International concerning software patentability have become apparent as other courts grapple with and implement that decision. The Web extra at http://youtu.be/Boa67CXBqPU is an audio recording of Brian M. Gaff reading his Computing and the Law column, in which he discusses how the ramifications of last year's US Supreme Court decision in Alice Corp. v. CLS Bank International concerning software patentability have become apparent as other courts grapple with and implement that decision.
Autors: Gaff, Brian M.;
Appeared in: Computer
Publication date: Jul 2015, volume: 48, issue:7, pages: 12 - 14
Publisher: IEEE
 
» Ω-Shaped Axial-Flux Permanent-Magnet Machine for Direct-Drive Applications With Constrained Shaft Height
Abstract:
This paper investigates an original solution that can be used in the design of axial-flux permanent-magnet (AFPM) machines whenever a constrained shaft height requirement penalizes a standard design. A machine is tailored for electrical traction, but the ideas that are set forth are valid for any application with a constrained shaft height. Two design solutions that comply with a constrained shaft height are investigated, i.e., a standard Torus AFPM machine and an asymmetrically wound Torus machine, which is named “Ω AFPM” due to the shape of the stator winding. It is shown that the Ω AFPM machine has lower losses and higher efficiency. Finite-element simulations and experimental tests on a full-scale prototype confirm the validity of the proposed solution.
Autors: De Donato, G.;Capponi, F.G.;Borocci, G.;Caricchi, F.;Beneduce, L.;Fratelli, L.;Tarantino, A.;
Appeared in: IEEE Transactions on Industry Applications
Publication date: Jul 2015, volume: 51, issue:4, pages: 3050 - 3058
Publisher: IEEE
 
» 100-MHz Low-Phase-Noise Microprocessor Temperature-Compensated Crystal Oscillator
Abstract:
An AT-cut third-overtone 100-MHz quartz crystal resonator was used to achieve a 100-MHz low-phase-noise voltage-controlled crystal oscillator prototype. The unloaded quality factor of the used resonator is about 132 K, and the equivalent dynamic capacitance is about 1.2 fF. For the characteristic of the large equivalent dynamic capacitance of the resonator, the design method and the actual measured data of the low-phase-noise oscillator prototype are given. An explanation of why larger equivalent dynamic capacitance and higher voltage-control sensitivity can lead to bad phase noise in half-bandwidth is given. The STM32F103RCT6 MCU is used to read the real-time data of temperature sensor of the microprocessor temperature-compensated crystal oscillator (MTCXO) and the real-time control voltage loading on the MTCXO. Therefore, the real-time communication between a personal computer and an MTCXO is achieved. The control voltage achieved in this way has already considered both the effect of the actual working condition of the MTCXO circuit and the effect of the MTCXO internal reference voltage that it is not accurate enough. After temperature compensation, the measured temperature performance of the 100-MHz low-phase-noise MTCXO are better than ±0.45 ppm/−30 °C –+50 ° C, and measured phase noise results are better than −157 dBc/Hz at 1 KHz and −170 dBc/Hz at 10 KHz.
Autors: Huang, X.;Liu, D.;Wang, Y.;Chen, P.;Fu, W.;
Appeared in: IEEE Transactions on Circuits and Systems II: Express Briefs
Publication date: Jul 2015, volume: 62, issue:7, pages: 636 - 640
Publisher: IEEE
 
» 130-320-GHz CMOS Harmonic Down-Converters Around and Above the Cutoff Frequency
Abstract:
We present an analytical model, design, and measurement results on fundamental, harmonic, and subharmonic down conversion mixing approaches in 65-nm CMOS around and above the transistor cutoff frequency , targeting submillimeter-wave operation. Analytical expressions for the mixing approaches are derived and compared with the simulation and measurement results. To investigate how to improve the performance of a passive mixer around and beyond , the relation between local oscillator (LO) harmonics (including both the harmonic amplitude and phase), mixer gate bias, and conversion gain is studied. To demonstrate mixing approaches, we present integrated 160- and 280-GHz down-converters with integrated LO manufactured in 65-nm CMOS process with . The LO in both down-converters is based on exploiting higher harmonics of a differential Colpitts topology voltage-controlled oscillator (VCO). Passive conversion losses of 22 and 25.5 dB are obtained over the 150–180-GHz and the 230–290-GHz frequency range, respectively. Two additional versions of the down converter at 170 and 280 GHz, respectively, without integrated VCO are also presented to examine the mixer performance in the 110–325-GHz range.
Autors: Khamaisi, B.;Socher, E.;
Appeared in: IEEE Transactions on Microwave Theory and Techniques
Publication date: Jul 2015, volume: 63, issue:7, pages: 2275 - 2288
Publisher: IEEE
 
» 1305-nm Quantum Dot Vertical-External-Cavity Surface-Emitting Laser
Abstract:
We report the first room temperature quantum dot (QD) vertical-external-cavity surface-emitting laser operating at 1305 nm. The gain structure was composed of QD layers; each threefold group was positioned at an antinode of the standing wave of the optical field. Continuous wave optical output power >0.5 mW with threshold pump power of 21 mW was demonstrated using a very simple and compact laser configuration by employing a high reflection-coated fiber as the top mirror. Using a piezoelectric translation stage, the emission wavelength could be tuned over a 14-nm spectral range.
Autors: Alharthi, S.S.;Clarke, E.;Henning, I.D.;Adams, M.J.;
Appeared in: IEEE Photonics Technology Letters
Publication date: Jul 2015, volume: 27, issue:14, pages: 1489 - 1491
Publisher: IEEE
 
» 1D Selection Device Using Carbon Nanotube FETs for High-Density Cross-Point Memory Arrays
Abstract:
A novel one-transistor-n-resistors (1TnR) array architecture is demonstrated as a cost-effective solution to the sneak path problem in large-scale cross-point memory arrays. In a 1TnR array, a single transistor (1T) with a 1D channel effectively controls a number of resistive switching nonvolatile memory (NVM) cells (nR) while limiting the sneak leakage current within the 1D channel without sacrificing the device density. To maximize these benefits, a carbon nanotube FET (CNFET) is employed as the 1D selection device, due to its near-ballistic electrical transport properties even at a small device width. Experimental demonstrations of the CNFET-based 1TnR concept are presented with two promising resistive switching NVM candidates: 1) resistive random access memory (RRAM) and 2) phase-change memory (PCM). Here, we report that the integrated bipolar Al2O3-based RRAM consumes programming energies as low as 0.1–7 pJ per bit and has a high programming endurance of up to cycles. The 1TnR RRAM cell also has self-compliance characteristics, because the semiconducting carbon nanotube (CNT) that serves as the bottom electrode limits the device current. The unipolar PCM cells integrated with CNFETs show uniform electrical characteristics with high ON-/OFF-resistance ratios of >10. Owing to the extremely small contact area between the phase change material, Ge2Sb2Te5, and the CNT, remarkably low programming currents of are achieved.
Autors: Ahn, C.;Jiang, Z.;Lee, C.;Chen, H.;Liang, J.;Liyanage, L.S.;Wong, H.P.;
Appeared in: IEEE Transactions on Electron Devices
Publication date: Jul 2015, volume: 62, issue:7, pages: 2197 - 2204
Publisher: IEEE
 
» 3-D Imaging of a Microwave Absorber Sample From Microwave Scattered Field Measurements
Abstract:
The internal structure of a sample of an absorber is retrieved from its measured scattered field. By its very nature, this target is a very weak-scatterer as it is used to cover the walls in anechoic chambers. The real part of its permittivity is rather small but its dielectric losses are non negligible. Quantitative maps of the complex permittivity of the sample were obtained from monochromatic scattered fields measured inside an anechoic chamber in a multistatic configuration. An imaging procedure taking into account the noise characteristics disturbing the measurements was used for this purpose.
Autors: Geffrin, J.-M.;Eyraud, C.;Litman, A.;
Appeared in: IEEE Microwave and Wireless Components Letters
Publication date: Jul 2015, volume: 25, issue:7, pages: 472 - 474
Publisher: IEEE
 
» 3-D Numerical Hybrid Method for PM Eddy-Current Losses Calculation: Application to Axial-Flux PMSMs
Abstract:
This paper describes a 3-D numerical hybrid method (NHM) of the permanent-magnet (PM) eddy-current losses in axial-flux PM synchronous machines (PMSMs). The PM magnetic flux density is determined using the multi-static 3-D finite-element method (FEM) at resistance-limited (i.e., without eddy-current reaction field). Based on the predicted flux density distribution, the eddy-currents induced in the PMs and the 3-D PM eddy-current losses are calculated by 3-D finite-difference method (FDM) considering a large mesh. Therefore, this 3-D NHM is based on a coupling between the multi-static 3-D FEM and the 3-D FDM. Two 24-slots/16-poles (i.e., fractional-slot number) axial-flux PMSMs having a non-overlapping winding (all teeth wound type) with stator double-sided structure are studied: 1) surface-PM (SPM) and 2) interior-PM (IPM) To evaluate the reliability of the proposed technique, the 3-D PM eddy-current losses are determined and compared with transient 3-D FEM (i.e., magneto-dynamical 3-D FEM). The same nonlinear properties of the laminations have been applied for multi-static/transient 3-D FEM. The computation time can be divided by 25 with a difference less than 12%.
Autors: Benlamine, R.;Dubas, F.;Randi, S.;Lhotellier, D.;Espanet, C.;
Appeared in: IEEE Transactions on Magnetics
Publication date: Jul 2015, volume: 51, issue:7, pages: 1 - 10
Publisher: IEEE
 
» 3-D Stent Detection in Intravascular OCT Using a Bayesian Network and Graph Search
Abstract:
Worldwide, many hundreds of thousands of stents are implanted each year to revascularize occlusions in coronary arteries. Intravascular optical coherence tomography is an important emerging imaging technique, which has the resolution and contrast necessary to quantitatively analyze stent deployment and tissue coverage following stent implantation. Automation is needed, as current, it takes up to 16 h to manually analyze hundreds of images and thousands of stent struts from a single pullback. For automated strut detection, we used image formation physics and machine learning via a Bayesian network, and 3-D knowledge of stent structure via graph search. Graph search was done on en face projections using minimum spanning tree algorithms. Depths of all struts in a pullback were simultaneously determined using graph cut. To assess the method, we employed the largest validation data set used so far, involving more than 8000 clinical images from 103 pullbacks from 72 patients. Automated strut detection achieved a recall, and precision. Performance was robust in images of varying quality. This method can improve the workflow for analysis of stent clinical trial data, and can potentially be used in the clinic to facilitate real-time stent analysis and visualization, aiding stent implantation.
Autors: Wang, Z.;Jenkins, M.W.;Linderman, G.C.;Bezerra, H.G.;Fujino, Y.;Costa, M.A.;Wilson, D.L.;Rollins, A.M.;
Appeared in: IEEE Transactions on Medical Imaging
Publication date: Jul 2015, volume: 34, issue:7, pages: 1549 - 1561
Publisher: IEEE
 
» 3D Microendoscopic Electrical Impedance Tomography for Margin Assessment During Robot-Assisted Laparoscopic Prostatectomy
Abstract:
Radially configured microendoscopic electrical impedance probes intended for intraoperative surgical margin assessment during robot-assisted laparoscopic prostatectomy (RALP) were examined through simulation, bench-top experimentation, and ex vivo tissue studies. Three probe designs with 8, 9, and 17 electrodes, respectively, were analyzed through finite element method based simulations. One mm diameter spherical inclusions ( ) are positioned at various locations within a hemispherical background ( ) of radius 5 mm. An 8-electrode configuration is not able to localize the inclusion at these positions while 9 and 17-electrode configurations are able to accurately reconstruct the inclusion at maximum depth of 1 mm and 3 mm, respectively. All three probe designs were constructed and evaluated using saline phantoms and ex vivo porcine and human prostate tissues. The 17-electrode probe performed best in saline phantom studies, accurately reconstructing high contrast, 1-mm-diameter metal cylindrical inclusions in a saline bath ( ) with a position and area error of 0.46 mm and 0.84 , respectively. Additionally, the 17-electrode probe was able to adequately distinguish cancerous from benign tissues in three ex vivo human prostates. Simulations, bench-top saline experiments, and ex vivo tissue sampling suggest that for intraoperative surgical margin assessment during RALP, the 17-electrode probe (as compared to an 8 and 9 electrode probe) will be necessary to provide sufficient accuracy and sensitivity.
Autors: Mahara, A.;Khan, S.;Murphy, E.K.;Schned, A.R.;Hyams, E.S.;Halter, R.J.;
Appeared in: IEEE Transactions on Medical Imaging
Publication date: Jul 2015, volume: 34, issue:7, pages: 1590 - 1601
Publisher: IEEE
 
» 5G Spectrum: enabling the future mobile landscape [Guest Editorial]
Abstract:
The arrival of the fifth generation (5G) is expected to come together with three important enablers. First, the densification of access nodes will continue. Second, 5G networks must be highly flexible and adapt to the dynamism of the traffic location and patterns. For this, some of the radio access network (RAN) functionalities will run in large computer centers, able to dynamically assign more or fewer units of computation to the virtual cells distributed in the network. Finally, a complex landscape of spectrum availability and access will emerge where multiple frequency bands, subject to different regulations including various forms of shared spectrum, are expected to be available to wireless communication systems.
Autors: Schotten, H.D.;Uusitalo, M.A.;Monserrat, J.F.;Queseth, O.;
Appeared in: IEEE Communications Magazine
Publication date: Jul 2015, volume: 53, issue:7, pages: 16 - 17
Publisher: IEEE
 
» 5G Spectrum: is china ready?
Abstract:
With a considerable ratio of the world???s mobile users, China has been actively promoting research on 5G, in which the spectrum issue is of great interest. New 5G characteristics put forward a lot of requirements for spectrum in terms of total amount, candidate bands, as well as new challenges for spectrum usage methods and management. Based on China???s current situation, this article first discusses the 5G vision, spectrum demands, and potential candidate bands. Furthermore, it is indicated that spectrum sharing will bring many benefits for 5G systems, and different sharing scenarios are summarized. Finally, based on the current framework of spectrum management in China, potential services classification and spectrum assessment are proposed to accommodate new 5G requirements.
Autors: Wang, T.;Li, G.;Ding, J.;Miao, Q.;Li, J.;Wang, Y.;
Appeared in: IEEE Communications Magazine
Publication date: Jul 2015, volume: 53, issue:7, pages: 58 - 65
Publisher: IEEE
 
» 5G wireless network: MyNET and SONAC
Abstract:
Future 5G wireless networks will face new challenges, including increasing demand on network capacity to support a large number of devices running applications requiring high data rates and always-on connectivity; immensely diverse service requirements and characteristics; and supporting the emerging business models in the wireless network market requiring networks to be more open. New challenges drive new solutions and require different strategies in the network deployment, management, and operation of future 5G wireless networks compared to those of current wireless networks. One of the key objectives of future 5G wireless networks is to flexibly provide service-customized networks to a wide variety of services using the integrated cloud resource and wireless/wired network resources, which may be offered by multiple infrastructure providers and/or operators. In this article, we describe a novel wireless network architecture, MyNET, and one of the key enabling techniques called SONAC. In MyNET, basic logical functions are identified for both the control plane and the data plane. These basic functions include existing network functions, with some extensions/enhancements, as well as new network functions. SONAC selects and deploys a subset of these functions to provide customized network services.
Autors: Zhang, H.;Vrzic, S.;Senarath, G.;D??o, N.-D.;Farmanbar, H.;Rao, J.;Peng, C.;Zhuang, H.;
Appeared in: IEEE Network
Publication date: Jul 2015, volume: 29, issue:4, pages: 14 - 23
Publisher: IEEE
 
» 60-GHz Polarization-Adjustable Antenna Arrays
Abstract:
This paper proposes and polarization-adjustable millimeter-wave antenna arrays. The antennas were designed to function at 60 GHz and are planar and vialess. The proposed antenna designs contain two input ports; if the input phases and magnitudes of the two input ports can be controlled, enabling the proposed antenna to generate six types of polarization: right-handed circular polarization, left-handed circular polarization, and linear polarization along the , , , and axes. The achieved antenna gain of the polarization diversity array was approximately 12 dBi, whereas that of the array was 16 dBi. Prototypes of both the and arrays were fabricated and tested. The operating mechanism and design steps are described in detail in this paper.
Autors: Chi, Y.;Chen, F.;
Appeared in: IEEE Transactions on Antennas and Propagation
Publication date: Jul 2015, volume: 63, issue:7, pages: 2887 - 2894
Publisher: IEEE
 
» 8.1 nJ/b 2.4 GHz Short-Range Communication Receiver in 65 nm CMOS
Abstract:
An 8.1 nJ/bit 2.4 GHz receiver with integrated digital baseband supporting O-QPSK DSSS modulation compliant with the IEEE 802.15.4 standard is presented that targets short-range, Internet of Things applications (IoTs). The sensitivity of a wireless communication receiver in general trades with power consumption. This receiver exploits this tradeoff to achieve a total power consumption of 2.02 mW including ADCs and digital baseband processing, at a sensitivity of 52.5 dBm at 250 Kbps. The energy-efficiency of the radio frequency (RF) front-end alone is nearly 2x better than the prior art. The receiver was fabricated in 65 nm CMOS with an area of 0.86 .
Autors: Khan, O.U.;Wentzloff, D.D.;
Appeared in: IEEE Transactions on Circuits and Systems I: Regular Papers
Publication date: Jul 2015, volume: 62, issue:7, pages: 1854 - 1862
Publisher: IEEE
 
» -Connectivity in Random Key Graphs With Unreliable Links
Abstract:
Random key graphs form a class of random intersection graphs that are naturally induced by the random key predistribution scheme of Eschenauer and Gligor for securing wireless sensor network (WSN) communications. Random key graphs have received much attention recently, owing in part to their wide applicability in various domains, including recommender systems, social networks, secure sensor networks, clustering and classification analysis, and cryptanalysis to name a few. In this paper, we study connectivity properties of random key graphs in the presence of unreliable links. Unreliability of graph links is captured by independent Bernoulli random variables, rendering them to be on or off independently from each other. The resulting model is an intersection of a random key graph and an Erdos-Renyi graph, and is expected to be useful in capturing various real-world networks; e.g., with secure WSN applications in mind, link unreliability can be attributed to harsh environmental conditions severely impairing transmissions. We present conditions on how to scale this model's parameters so that: 1) the minimum node degree in the graph is at least k and 2) the graph is k-connected, both with high probability as the number of nodes becomes large. The results are given in the form of zero-one laws with critical thresholds identified and shown to coincide for both graph properties. These findings improve the previous results by Rybarczyk on k-connectivity of random key graphs (with reliable links), as well as the zero-one laws by Yagan on one-connectivity of random key graphs with unreliable links.
Autors: Jun Zhao;Yagan, O.;Gligor, V.;
Appeared in: IEEE Transactions on Information Theory
Publication date: Jul 2015, volume: 61, issue:7, pages: 3810 - 3836
Publisher: IEEE
 
» -Transforms for Wireless Communication
Abstract:
The H-transforms are integral transforms that involve Fox's H-functions as kernels. A large variety of integral transforms can be put into particular forms of the H-transform since H-functions subsume most of the known special functions including Meijer's G-functions. In this paper, we embody the H-transform theory into a unifying framework for modeling and analysis in wireless communication. First, we systematize the use of elementary identities and properties of the H-transform by introducing operations on parameter sequences of H-functions. We then put forth H-fading and degree-2 irregular H-fading to model radio propagation under composite, specular, and/or inhomogeneous conditions. The H-fading describes composite effects of multipath fading and shadowing as a single H-variate, including most of typical models such as Rayleigh, Nakagami-m, Weibull, α-μ, N*Nakagami-m, (generalized) K-fading, and Weibull/gamma fading as its special cases. As a new class of H-variates (called the degree-ζ irregular H-variate), the degree-2 irregular H-fading characterizes specular and/or inhomogeneous radio propagation in which the multipath component consists of a strong specularly reflected or line-of-sight (LOS) wave as well as unequal-power or correlated in-phase and quadrature scattered waves. This fading includes a variety of typical models such as Rician, Nakagami-q, κ-μ, η-μ, Rician/LOS gamma, and κ-μ/LOS gamma fading as its special cases. Finally, we develop a unifying H-transform analysis for the amount of fading, error probability, channel capacity, and error exponent in wireless communication using the new systematic language of transcendental H-functions. By virtue of two essential operations-called Mellin and convolution operations-involved in the Mellin transform and Mellin convolution of two H-functions, the H-transforms for these performance measures culminate in H-functions. Usi- g the algebraic asymptotic expansions of the H-transform, we further analyze the error probability and capacity at high and low signal-to-noise ratios in a unified fashion.
Autors: Youngmin Jeong;Hyundong Shin;Win, M.Z.;
Appeared in: IEEE Transactions on Information Theory
Publication date: Jul 2015, volume: 61, issue:7, pages: 3773 - 3809
Publisher: IEEE
 
» Equivalence: A Phenomenon Hidden Among Sparsity Models Minimization and Minimization for Information Processing
Abstract:
In this paper, we have proved that in every underdetermined linear system Ax = b, there corresponds a constant p*(A, b) > 0 such that every solution to the l p-norm minimization problem also solves the l0-norm minimization problem whenever 0 <; p <; p*(A, b). This phenomenon is named NP/CMP equivalence.
Autors: Jigen Peng;Shigang Yue;Haiyang Li;
Appeared in: IEEE Transactions on Information Theory
Publication date: Jul 2015, volume: 61, issue:7, pages: 4028 - 4033
Publisher: IEEE
 
» Minimization Based Symbol Detection for Generalized Space Shift Keying
Abstract:
Generalized space shift keying (GSSK), as one simplified version of spatial modulation (SM), has attracted plenty of interest in the study of large-scale multiple-input multiple-output (MIMO). In this letter, we propose a low-complexity symbol detector for GSSK based on minimization. Via a bijective transformation, the symbol detection for GSSK can be converted into the reconstruction of a binary symbol, of which the entries are selected from . The reconstruction is done by solving an minimization problem, which is convex and can be solved by many off-the-shelf optimization tools. The new detection scheme is capable of detecting GSSK symbols under overdetermined and underdetermined MIMO systems and only requires a polynomial complexity. Numerical simulations are further performed to substantiate the performance of the proposed detector.
Autors: He, L.;Wang, J.;Ding, W.;Song, J.;
Appeared in: IEEE Communications Letters
Publication date: Jul 2015, volume: 19, issue:7, pages: 1109 - 1112
Publisher: IEEE
 
» -Transforms for Wireless Communication
Abstract:
The H-transforms are integral transforms that involve Fox's H-functions as kernels. A large variety of integral transforms can be put into particular forms of the H-transform since H-functions subsume most of the known special functions including Meijer's G-functions. In this paper, we embody the H-transform theory into a unifying framework for modeling and analysis in wireless communication. First, we systematize the use of elementary identities and properties of the H-transform by introducing operations on parameter sequences of H-functions. We then put forth H-fading and degree-2 irregular H-fading to model radio propagation under composite, specular, and/or inhomogeneous conditions. The H-fading describes composite effects of multipath fading and shadowing as a single H-variate, including most of typical models such as Rayleigh, Nakagami-m, Weibull, α-μ, N*Nakagami-m, (generalized) K-fading, and Weibull/gamma fading as its special cases. As a new class of H-variates (called the degree-ζ irregular H-variate), the degree-2 irregular H-fading characterizes specular and/or inhomogeneous radio propagation in which the multipath component consists of a strong specularly reflected or line-of-sight (LOS) wave as well as unequal-power or correlated in-phase and quadrature scattered waves. This fading includes a variety of typical models such as Rician, Nakagami-q, κ-μ, η-μ, Rician/LOS gamma, and κ-μ/LOS gamma fading as its special cases. Finally, we develop a unifying H-transform analysis for the amount of fading, error probability, channel capacity, and error exponent in wireless communication using the new systematic language of transcendental H-functions. By virtue of two essential operations-called Mellin and convolution operations-involved in the Mellin transform and Mellin convolution of two H-functions, the H-transforms for these performance measures culminate in H-functions. Usi- g the algebraic asymptotic expansions of the H-transform, we further analyze the error probability and capacity at high and low signal-to-noise ratios in a unified fashion.
Autors: Youngmin Jeong;Hyundong Shin;Win, M.Z.;
Appeared in: IEEE Transactions on Information Theory
Publication date: Jul 2015, volume: 61, issue:7, pages: 3773 - 3809
Publisher: IEEE
 
» -Connectivity in Random Key Graphs With Unreliable Links
Abstract:
Random key graphs form a class of random intersection graphs that are naturally induced by the random key predistribution scheme of Eschenauer and Gligor for securing wireless sensor network (WSN) communications. Random key graphs have received much attention recently, owing in part to their wide applicability in various domains, including recommender systems, social networks, secure sensor networks, clustering and classification analysis, and cryptanalysis to name a few. In this paper, we study connectivity properties of random key graphs in the presence of unreliable links. Unreliability of graph links is captured by independent Bernoulli random variables, rendering them to be on or off independently from each other. The resulting model is an intersection of a random key graph and an Erdos-Renyi graph, and is expected to be useful in capturing various real-world networks; e.g., with secure WSN applications in mind, link unreliability can be attributed to harsh environmental conditions severely impairing transmissions. We present conditions on how to scale this model's parameters so that: 1) the minimum node degree in the graph is at least k and 2) the graph is k-connected, both with high probability as the number of nodes becomes large. The results are given in the form of zero-one laws with critical thresholds identified and shown to coincide for both graph properties. These findings improve the previous results by Rybarczyk on k-connectivity of random key graphs (with reliable links), as well as the zero-one laws by Yagan on one-connectivity of random key graphs with unreliable links.
Autors: Jun Zhao;Yagan, O.;Gligor, V.;
Appeared in: IEEE Transactions on Information Theory
Publication date: Jul 2015, volume: 61, issue:7, pages: 3810 - 3836
Publisher: IEEE
 
» Equivalence: A Phenomenon Hidden Among Sparsity Models Minimization and Minimization for Information Processing
Abstract:
In this paper, we have proved that in every underdetermined linear system Ax = b, there corresponds a constant p*(A, b) > 0 such that every solution to the l p-norm minimization problem also solves the l0-norm minimization problem whenever 0 <; p <; p*(A, b). This phenomenon is named NP/CMP equivalence.
Autors: Jigen Peng;Shigang Yue;Haiyang Li;
Appeared in: IEEE Transactions on Information Theory
Publication date: Jul 2015, volume: 61, issue:7, pages: 4028 - 4033
Publisher: IEEE
 
» -Band Coherent Wireless Link Using Injection-Locked Laser Diodes
Abstract:
We demonstrate that the simultaneous injection locking of two monolithically integrated distributed feedback (DFB) laser diodes (LDs) with an optical frequency comb is a feasible technique for photonic-based carrier signal generation in the real-time coherent wireless link. The phase of the carrier signal generated by heterodyning the two injection-locked DFB LDs is sufficiently stable to achieve 10-Gb/s error-free (bit-error rate ) coherent wireless transmission in the -band (75–110 GHz) without active phase stabilization on the transmitter side and digital signal processing on the receiver side. Compared with a direct detection scheme, we show a 17-dB sensitivity improvement using coherent detection. These results open the path toward the development of compact and cost-effective coherent photonic wireless transmitters based on state-of-the-art InP photonic integrated circuit technology, which have wider bandwidth compared with electronics-based transmitters.
Autors: Hisatake, S.;Carpintero, G.;Yoshimizu, Y.;Minamikata, Y.;Oogimoto, K.;Yasuda, Y.;van Dijk, F.;Tekin, T.;Nagatsuma, T.;
Appeared in: IEEE Photonics Technology Letters
Publication date: Jul 2015, volume: 27, issue:14, pages: 1565 - 1568
Publisher: IEEE
 
» A 0.07 mm 2.2 mW 10 GHz Current-Reuse Class-B/C Hybrid VCO Achieving 196-dBc/Hz FoM
Abstract:
This Letter describes a current-reuse class-B/C hybrid voltage-controlled oscillator (VCO) with robust startup, enhanced phase noise and differential balancing at small area and power. Specifically, an asymmetrical CMOS class-C core is aided by a symmetrical NMOS-only class-B core that effectively shares the bias current for deeper class-C operation of the former; wider margin of startup against PVT variations, and lower amplitude imbalance against oscillation frequencies. Moreover, this topology adds the freedom of adjustable peak dynamic current and boosts the oscillation swing at low power. The spiral inductors with patterned ground shields shrink the die size. Fabricated in 65 nm CMOS, the 0.07 mm VCO prototype exhibits 10.15-to-11.17 GHz tunability, and -dBc/Hz phase noise at 1 MHz offset, while dissipating merely 2.2 mW at 1.2 V. The achieved area-included figure-of-merit (FoM dBc/Hz) favorably compares with the state-of-the-art.
Autors: Amin, M.T.;Yin, J.;Mak, P.-I.;Martins, R.P.;
Appeared in: IEEE Microwave and Wireless Components Letters
Publication date: Jul 2015, volume: 25, issue:7, pages: 457 - 459
Publisher: IEEE
 
» A 0.07 mm 2.2 mW 10 GHz Current-Reuse Class-B/C Hybrid VCO Achieving 196-dBc/Hz FoM
Abstract:
This Letter describes a current-reuse class-B/C hybrid voltage-controlled oscillator (VCO) with robust startup, enhanced phase noise and differential balancing at small area and power. Specifically, an asymmetrical CMOS class-C core is aided by a symmetrical NMOS-only class-B core that effectively shares the bias current for deeper class-C operation of the former; wider margin of startup against PVT variations, and lower amplitude imbalance against oscillation frequencies. Moreover, this topology adds the freedom of adjustable peak dynamic current and boosts the oscillation swing at low power. The spiral inductors with patterned ground shields shrink the die size. Fabricated in 65 nm CMOS, the 0.07 mm VCO prototype exhibits 10.15-to-11.17 GHz tunability, and -dBc/Hz phase noise at 1 MHz offset, while dissipating merely 2.2 mW at 1.2 V. The achieved area-included figure-of-merit (FoM dBc/Hz) favorably compares with the state-of-the-art.
Autors: Amin, M.T.;Yin, J.;Mak, P.-I.;Martins, R.P.;
Appeared in: IEEE Microwave and Wireless Components Letters
Publication date: Jul 2015, volume: 25, issue:7, pages: 457 - 459
Publisher: IEEE
 
» A 0.41 pJ/Bit 10 Gb/s Hybrid 2 IIR and 1 Discrete-Time DFE Tap in 28 nm-LP CMOS
Abstract:
An ideal infinite impulse response (IIR) decision feedback equalizer (DFE) can have an effect on wireline received waveforms similar to a continuous-time equalizer, but without the associated amplification of noise and crosstalk. However, an IIR DFE's performance degrades significantly as the feedback loop delay increases. Fortunately, adding a single discrete-time tap can eliminate the degradation. The implementation of a half-rate DFE with two IIR taps and one discrete-time tap is presented here. The two IIR filters have different time constants to accommodate a variety of channel pulse responses having a long tail. The discrete-time tap cancels the first post-cursor inter-symbol interference (ISI) term and alleviates feedback loop timing issues. The DFE can receive data transmitted with a low swing of 150 mVpp-diff through 24 dB of channel loss at half the bitrate while consuming 4.1 mW at 10 Gb/s. Digital foreground calibration of clock phase shifters and offset cancellation is described. The receiver, including the DFE, clock buffers and clock phase adjustment, occupies an area of 8760 µm 2 in an ST 28 nm LP CMOS process.
Autors: Shahramian, S.;Chan Carusone, A.;
Appeared in: IEEE Journal of Solid-State Circuits
Publication date: Jul 2015, volume: 50, issue:7, pages: 1722 - 1735
Publisher: IEEE
 
» A 0.45-V, 14.6-nW CMOS Subthreshold Voltage Reference With No Resistors and No BJTs
Abstract:
We present a low-voltage low-power CMOS subthreshold voltage reference with no resistors and no bipolar junction transistors in a wide temperature range. The temperature stability is improved by second-order compensation. By employing a bulk-driven technique and the MOS transistors working in the subthreshold region, the supply voltage and the power dissipation are reduced. Moreover, a trimming circuit is adopted to compensate for the process-related reference voltage variation. The proposed voltage reference has been fabricated with the 0.18- 1.8-V CMOS process. The measurement results show that the minimum power supply voltage is 0.45 V, the power consumption is 14.6 nW, the average temperature coefficient measured from to 125 °C is 63.6 ppm/°C, and the line regulation is 1.2 mV/V in the power supply voltage ranging from 0.45 to 1.8 V. In addition, the chip area is 0.012 mm2.
Autors: Wang, Y.;Zhu, Z.;Yao, J.;Yang, Y.;
Appeared in: IEEE Transactions on Circuits and Systems II: Express Briefs
Publication date: Jul 2015, volume: 62, issue:7, pages: 621 - 625
Publisher: IEEE
 
» A 1.1-Gbit/s 10-GHz Outphasing Modulator With 23-dBm Output Power and 60-dB Dynamic Range in 45-nm CMOS SOI
Abstract:
A 10-GHz outphasing modulator is implemented in a 45-nm CMOS silicon-on-insulator process. The modulator is designed to provide high linearity and can operate at high data rates by using 256-QAM while maintaining low error vector magnitude (EVM). Four high-speed 10-bit digital-to-analog converters (DACs) are integrated with dual in-phase and quadrature upconverters. To deliver high output power to an off-chip power amplifier, stacked field-effect transistor current buffers are used to isolate the modulator from the load and mitigate device breakdown. As a result, this modulator delivers 23 dBm to a differential 100- load. The high-resolution DACs provide a fine control of the phase between the outphased signals and support more than 60 dB of dynamic range and power steps smaller than 1 dB over the entire output power range. The outphasing modulator demonstrates an EVM of 2.2% at 80 Mbit/s and an EVM of 3.4% at 1.1 Gbit/s for 256-QAM. To our knowledge, this is the first demonstration of an outphasing modulator operating above 1 Gb/s.
Autors: Mehrjoo, M.S.;Zihir, S.;Rebeiz, G.M.;Buckwalter, J.F.;
Appeared in: IEEE Transactions on Microwave Theory and Techniques
Publication date: Jul 2015, volume: 63, issue:7, pages: 2289 - 2300
Publisher: IEEE
 
» A 110-nm CMOS 0.7-V Input Transient-Enhanced Digital Low-Dropout Regulator With 99.98% Current Efficiency at 80-mA Load
Abstract:
This paper presents a digital low-dropout regulator (D-LDO) with a proposed transient-response boost technique, which enables the reduction of transient response time, as well as overshoot/undershoot, when the load current is abruptly drawn. The proposed D-LDO detects the deviation of the output voltage by overshoot/undershoot, and increases its loop gain, for the time that the deviation is beyond a limit. Once the output voltage is settled again, the loop gain is returned. With the D-LDO fabricated on an 110-nm CMOS technology, we measured its settling time and peak of undershoot, which were reduced by 60% and 72%, respectively, compared with and without the transient-response boost mode. Using the digital logic gates, the chip occupies a small area of 0.04 mm , and it achieves a maximum current efficiency of 99.98%, by consuming the quiescent current of 15 A at 0.7-V input voltage.
Autors: Oh, T.;Hwang, I.;
Appeared in: IEEE Transactions on Very Large Scale Integration Systems
Publication date: Jul 2015, volume: 23, issue:7, pages: 1281 - 1286
Publisher: IEEE
 
» A 12 b 53 mW 195 MS/s Pipeline ADC with 82 dB SFDR Using Split-ADC Calibration
Abstract:
A 12 bit pipeline ADC with residue amplifiers calibrated for gain and distortion is presented. The settling accuracy of the residue amplifiers was lowered to achieve higher energy efficiency and the resulting errors were corrected in multiple stages using a split-ADC calibration technique. Starting from a typical op amp implementation, the settling accuracy of the residue amplifier was relaxed by a factor of more than 3x in the first two stages and by 2x in the remaining stages. The ADC was implemented in 40 nm digital CMOS and shows a Schreier figure-of-merit of 157.5 dB at 1 V supply, sampling at 195 MS/s, with an SNDR/SFDR of 64.8 dB/82 dB. While working in continuous background mode, the split-ADC calibration improved the ADC SFDR by 37 dB within 70,000 samples.
Autors: Sehgal, R.;van der Goes, F.;Bult, K.;
Appeared in: IEEE Journal of Solid-State Circuits
Publication date: Jul 2015, volume: 50, issue:7, pages: 1592 - 1603
Publisher: IEEE
 
» A 16 Channel High-Voltage Driver with 14 Bit Resolution for Driving Piezoelectric Actuators
Abstract:
A high-voltage, 16 channel driver with a maximum voltage of 72 volt and 14 bit resolution in a high-voltage CMOS (HV-CMOS) process is presented. This design incorporates a 14 bit monotonic by design DAC together with a high-voltage complementary class AB output stage for each channel. All 16 channels are used for driving a piezoelectric actuator within the control loop of a micropositioning system. Since the output voltages are static most of the time, a class AB amplifier is used, implementing voltage feedback to achieve 14 bit accuracy. The output driver consists of a push-pull stage with a built-in output current limitation and high-impedance mode. Also a protection circuit is added which limits the internal current when the output voltage saturates against the high-voltage rail. The 14 bit resolution of each channel is generated with a segmented resistor string DAC which assures monotonic by design behavior by using leapfrogging of the buffers used between segments. A diagonal shuffle layout is used for the resistor strings leading to cancellation of first order process gradients. The dense integration of 16 channels with high peak currents results in crosstalk, countered in this design by using staggered switching and resampling of the output voltages.
Autors: Pierco, R.;Torfs, G.;Verbrugghe, J.;Bakeroot, B.;Bauwelinck, J.;
Appeared in: IEEE Transactions on Circuits and Systems I: Regular Papers
Publication date: Jul 2015, volume: 62, issue:7, pages: 1726 - 1736
Publisher: IEEE
 
» A 2-MHz 60-W Zero-Voltage-Switching Synchronous Noninverting Buck–Boost Converter With Reduced Component Values
Abstract:
This brief presents a high-frequency high-efficiency zero-voltage-switching (ZVS) synchronous noninverting buck–boost converter for tens-of-Watt applications. By using two pairs of small auxiliary inductors and capacitors, the proposed converter can achieve ZVS under different load currents without increasing voltage stress across power field-effect transistors. The switching power loss is thus minimized to enable high-frequency operation of the converter. The proposed converter can be also configured into the boost mode or the buck mode with ZVS operation when the input voltage changes in order to maintain high power efficiency under different input voltages. The proposed noninverting buck–boost converter has been implemented to operate at 2 MHz and deliver 60-W output. The measured peak power efficiency achieves 94.3%, and the output capacitance and its volume can be reduced by at least 14 times and 4.8 times compared with other state-of-the-art counterparts.
Autors: Xue, J.;Lee, H.;
Appeared in: IEEE Transactions on Circuits and Systems II: Express Briefs
Publication date: Jul 2015, volume: 62, issue:7, pages: 716 - 720
Publisher: IEEE
 
» A 28 nm FDSOI Integrated Reconfigurable Switched-Capacitor Based Step-Up DC-DC Converter With 88% Peak Efficiency
Abstract:
This paper presents a fully integrated, reconfigurable switched-capacitor based step-up DC-DC converter in a 28 nm FDSOI process. Three reconfigurable step-up conversion ratios (5/2, 2/1, 3/2) have been implemented which can provide a wide range of output voltage from 1.2 V to 2.4 V with a nominal input voltage of 1 V. We propose a topology for the 5/2 mode which improves the efficiency by reducing the bottom-plate parasitic loss compared to a conventional series-parallel topology, while delivering the same amount of output power. Further, the proposed topology benefits from using core 1 V devices for all charge-transfer switches without incurring any voltage overstress. The converter can deliver load current in the range of 10 µA to 500 µA, achieving a peak efficiency of 88%, using only on-chip MOS and MOM capacitors for a high density implementation.
Autors: Biswas, A.;Sinangil, Y.;Chandrakasan, A.P.;
Appeared in: IEEE Journal of Solid-State Circuits
Publication date: Jul 2015, volume: 50, issue:7, pages: 1540 - 1549
Publisher: IEEE
 
» A 3-D Printed Lightweight X-Band Waveguide Filter Based on Spherical Resonators
Abstract:
A fifth order X-band waveguide bandpass filter, based on spherical resonators, has been designed, and fabricated by 3-D printing. In comparison with rectangular waveguide, spherical resonators have a higher unloaded quality factor, but at the same time suffer from closer higher order modes. In this letter, a special topology has been proposed to relieve the impact of the first three higher order modes in the resonator and ultimately to achieve a good out-of-band rejection. Stereolithography based 3-D printing is used to build the filter structure from polymer and a 25 thick copper layer is deposited to the filter. The measurement result of the filter has an excellent agreement with the simulations. The filter is also considerably lighter than a similar metal filter.
Autors: Guo, C.;Shang, X.;Lancaster, M.J.;Xu, J.;
Appeared in: IEEE Microwave and Wireless Components Letters
Publication date: Jul 2015, volume: 25, issue:7, pages: 442 - 444
Publisher: IEEE
 
» A 30/35 GHz Dual-Band Transmitter for Phased Arrays in Communication/Radar Applications
Abstract:
A fully integrated single-channel transmitter is proposed for 30/35 GHz dual-band operation for communication/radar phased array systems. Implemented in a 0.25 µm BiCMOS technology, the transmitter achieves 10° phase shift resolution and 5 bit amplitude resolution suitable for advanced beamforming algorithms for suppression and nulling of side lobes. The integration covers from the baseband I/Q modulation to the RF output, including a low phase noise on-chip VCO and dual-band LO generation circuitry. An RF output power of > +14.5 dBm is achieved in both frequency bands by a linear power amplifier. The core circuit occupies a die area of 1.1 mm 2Pub /_font and consumes 222–241 mA current from a 3.3 V supply.
Autors: Pei, Y.;Chen, Y.;Leenaerts, D.M.W.;van Roermund, A.H.M.;
Appeared in: IEEE Journal of Solid-State Circuits
Publication date: Jul 2015, volume: 50, issue:7, pages: 1629 - 1644
Publisher: IEEE
 
» A 33 MHz 70 dB-SNR Super-Source-Follower-Based Low-Pass Analog Filter
Abstract:
In this paper, a 4th-order low-pass continuous-time analog filter is presented, that is implemented with the cascade of two efficient and compact biquadratic cells, realized using the Super-Source-Follower topology. The biquadratic cell uses only two capacitors and four transistors: two transistors for the signal processing and two transistors as current sources for biasing purpose. The 4th-order filter prototype has been integrated in 0.18 µm CMOS technology. For a 33 MHz cut-off frequency, the filter performs 18 dBm-IIP3 for two tones at 2 MHz and 3 MHz, with total current of 770 µA from a single 1.8 V supply voltage.
Autors: De Matteis, M.;Pezzotta, A.;D'Amico, S.;Baschirotto, A.;
Appeared in: IEEE Journal of Solid-State Circuits
Publication date: Jul 2015, volume: 50, issue:7, pages: 1516 - 1524
Publisher: IEEE
 
» A 40 Gb/s Monolithically Integrated Linear Photonic Receiver in a BiCMOS SiGe:C Technology
Abstract:
This letter presents the first 40 Gb/s monolithically integrated silicon photonics linear receiver (Rx) comprising a germanium photodiode (Ge-PD) and a linear transimpedance amplifier (TIA). Measured optical-electrical (O/E) 3 dB bandwidth (BW) of the Rx is 31 GHz. At 40 Gb/s, the Rx achieves a sensitivity of average optical input power with BER of . It operates at wavelength, uses 3.3 and 3.7 V power supplies, dissipates 275 mW of power, provides maximum differential output amplitude of , and occupies an area of . The presented receiver achieves the highest bit rate among the published work in monolithically integrated silicon photonics receivers.
Autors: Awny, A.;Nagulapalli, R.;Winzer, G.;Kroh, M.;Micusik, D.;Lischke, S.;Knoll, D.;Fischer, G.;Kissinger, D.;Ulusoy, A.C.;Zimmermann, L.;
Appeared in: IEEE Microwave and Wireless Components Letters
Publication date: Jul 2015, volume: 25, issue:7, pages: 469 - 471
Publisher: IEEE
 
» A 40 nm CMOS I/O Pad Design With Embedded Capacitive Coupling Receiver for Non-Contact Wafer Probe Test
Abstract:
A receiver for capacitive coupled communication is embedded in a digital input/output pad to add the capacity for non-contact data communication, while maintaining size, ESD protection, and buffering functions unchanged, even in contact mode. The added feature allows non-contact probing of die pads and provides a reliable alternative solution to mechanical probing for electrical wafer sort testing of Systems-on-Chip (SoC) and Systems-in-Package (SiPs) because of elimination of pad damage and reduction of the force required to create stable electrical contacts between probe needles and pads. The proposed receiver detects the displacement current flowing through the capacitive channel created between the connecting probe needle and top metal pad surface when a transition in the input digital stimulus signal occurs. The receiver is designed to work up to 100 Mbit/s data rate with a power of 340 in a 40 nm CMOS process. The circuit trade-offs between frequency, amplitude of the step input and distance are discussed. Experimental results show that for a 5 V input voltage amplitude, the receiver allows correct data transmission at a distance up to 5 , which increases to 10 if the top aluminum layer is divided in two, using a customized I/O pad design. The feasibility of this non-contact testing approach was verified through electrical tests on two IP blocks, an LFSR, and a PLL with a scan chain, using a standard prober and a cantilever probe card designed with 19 needles of different lengths to enable both physical contact connections for power supply and non-contact capacitive coupling data communication for signals.
Autors: Scarselli, E.F.;Perilli, L.;Perugini, L.;Canegallo, R.;
Appeared in: IEEE Transactions on Circuits and Systems I: Regular Papers
Publication date: Jul 2015, volume: 62, issue:7, pages: 1737 - 1746
Publisher: IEEE
 
» A 40–67 GHz Power Amplifier With 13 dBm and 16% PAE in 28 nm CMOS LP
Abstract:
Pushed by the availability of large fractional bandwidths, many well-established applications are focusing mm-wave spectrum for product deployment. Generation of broadband power at mm-waves is challenging because a key target such as the efficiency trades with the gain-bandwidth (GBW) product. The major limit is the capacitive parasitics at the interstage between driver and power devices. The latter are designed with a large form factor so as to deliver the desired output power and are commonly biased in class-AB to achieve high drain efficiency, penalizing GBW. In this paper, a design methodology for interstage and output matching networks targeting large fractional bandwidth and high efficiency is proposed. Leveraging inductively coupled resonators, we apply Norton transformations for impedance scaling. In both networks, topological transformations are employed to include a transformer, achieve the desired load impedance and minimize the number of components. A two-stage differential PA with neutralized common source stages has been realized in 28 nm CMOS using low-power devices. The PA delivers 13 dBm saturated output power over the 40-67 GHz bandwidth with a peak power-added efficiency of 16% without power combining. To the best of author's knowledge, the presented PA shows state-of-the-art performances with the largest fractional bandwidth among bulk CMOS mm-wave PAs reported so far.
Autors: Bassi, M.;Junlei Zhao;Bevilacqua, A.;Ghilioni, A.;Mazzanti, A.;Svelto, F.;
Appeared in: IEEE Journal of Solid-State Circuits
Publication date: Jul 2015, volume: 50, issue:7, pages: 1618 - 1628
Publisher: IEEE
 
» A 600 µA 32 kHz Input 960 MHz Output CP-PLL With 530 ps Integrated Jitter in 28 nm FD-SOI Process
Abstract:
This paper presents a 32 kHz input and 960 MHz output low-power charge-pump phase-locked loop (CP-PLL) with a novel dual-path loop-filter for resistor noise reduction technique. The resistor noise reduction technique using dual-path loop-filter involves no “additional” active component; area/power overhead compared to the conventional CP-PLL. Reverse sub-threshold leakage compensated source-switched charge-pump (SS-CP) is employed in the PLL for improved reference spur performance. The PLL with minimum analog supply voltage of 1.62 V and minimum digital supply voltage of 0.65 V; with die area of 0.15 mm is designed and fabricated in 28 nm STMicroelectronics FD-SOI process. The silicon measurement results have been included and the PLL performance includes total integrated jitter of 530 ps, reference spur of 65 dBc and current consumption of 600 A.
Autors: Lahiri, A.;Gupta, N.;Kumar, A.;Dhadda, P.;
Appeared in: IEEE Journal of Solid-State Circuits
Publication date: Jul 2015, volume: 50, issue:7, pages: 1680 - 1689
Publisher: IEEE
 
» A 65-nm 25.1-ns 30.7-fJ Robust Subthreshold Level Shifter With Wide Conversion Range
Abstract:
Level shifters (LS) are crucial interface circuits for multisupply voltage designs, and it is challenging to achieve both robust and efficient level conversion from subthreshold to aforementioned threshold. In this brief, we propose two circuit techniques for a novel subthreshold LS with wide conversion range. First, we introduce a novel LS circuit with NMOS-diode-based current limiter for current contention reduction to achieve robust and efficient level conversion. Second, we explore the inverse narrow width effect to increase the drivability of the pull-down devices for delay reduction. When implemented in a commercial 65-nm MTCMOS process, the proposed LS achieves robust conversion from deep subthreshold (sub-100 mV) to nominal supply voltage (1.2 V). For the target conversion from 0.3 to 1.2 V, the proposed LS shows on average 25.1-ns propagation delay, 30.7-fJ energy efficiency, and 2.5-nW leakage power across 25 test chips.
Autors: Zhao, W.;Alvarez, A.B.;Ha, Y.;
Appeared in: IEEE Transactions on Circuits and Systems II: Express Briefs
Publication date: Jul 2015, volume: 62, issue:7, pages: 671 - 675
Publisher: IEEE
 
» A 9–11-Bit Phase-Interpolating Digital Pulsewidth Modulator With 1000x Frequency Range
Abstract:
A design of a new hybrid-type digital pulsewidth modulator (DPWM) with a wide frequency range of 1000 : 1, from 10 kHz to 10 MHz, is presented. The proposed DPWM has the maximum duty-cycle resolution of 11 bits and consumes the power of 17.5 at 10 kHz and 2.36 mW at 10 MHz, respectively. The proposed DPWM realizes the upper 5-bit resolution using a programmable digital counter and the lower 6-bit resolution using a current-integrating-type phase interpolator, employing an M2M-ladder current-steering digital-to-analog converter for low power consumption. The operating clock is generated in on-chip using a relaxation oscillator. The prototype integrated circuit fabricated in a 0.25- high-voltage complementary metal–oxide–semiconductor demonstrates that the proposed DPWM maintains a good linearity across the entire operating range.
Autors: Lee, Y.;Kang, T.;Kim, J.;
Appeared in: IEEE Transactions on Industry Applications
Publication date: Jul 2015, volume: 51, issue:4, pages: 3376 - 3384
Publisher: IEEE
 
» A -Controller-Based System for Interfacing Selectorless RRAM Crossbar Arrays
Abstract:
Selectorless crossbar arrays of resistive randomaccess memory (RRAM), also known as memristors, conduct large sneak currents during operation, which can significantly corrupt the accuracy of cross-point analog resistance (Mt) measurements. In order to mitigate this issue, we have designed, built, and tested a memristor characterization and testing (mCAT) instrument that forces redistribution of sneak currents within the crossbar array, dramatically increasing Mt measurement accuracy. We calibrated the mCAT using a custom-made 32 × 32 discrete resistive crossbar array, and subsequently demonstrated its functionality on solid-state TiO2-x RRAM arrays, on wafer and packaged, of the same size. Our platform can measure standalone Mt in the range of 1 kΩ to 1 MΩ with <;1% error. For our custom resistive crossbar, 90% of devices of the same resistance range were measured with <;10% error. The platform's limitations have been quantified using large-scale nonideal crossbar simulations.
Autors: Berdan, R.;Serb, A.;Khiat, A.;Regoutz, A.;Papavassiliou, C.;Prodromakis, T.;
Appeared in: IEEE Transactions on Electron Devices
Publication date: Jul 2015, volume: 62, issue:7, pages: 2190 - 2196
Publisher: IEEE
 
» A -Controller-Based System for Interfacing Selectorless RRAM Crossbar Arrays
Abstract:
Selectorless crossbar arrays of resistive random-access memory (RRAM), also known as memristors, conduct large sneak currents during operation, which can significantly corrupt the accuracy of cross-point analog resistance ( ) measurements. In order to mitigate this issue, we have designed, built, and tested a memristor characterization and testing (mCAT) instrument that forces redistribution of sneak currents within the crossbar array, dramatically increasing measurement accuracy. We calibrated the mCAT using a custom-made discrete resistive crossbar array, and subsequently demonstrated its functionality on solid-state TiO2-x RRAM arrays, on wafer and packaged, of the same size. Our platform can measure standalone in the range of 1 to 1 with <1% error. For our custom resistive crossbar, 90% of devices of the same resistance range were measured with <10% error. The platform’s limitations have been quantified using large-scale nonideal crossbar simulations.
Autors: Berdan, R.;Serb, A.;Khiat, A.;Regoutz, A.;Papavassiliou, C.;Prodromakis, T.;
Appeared in: IEEE Transactions on Electron Devices
Publication date: Jul 2015, volume: 62, issue:7, pages: 2190 - 2196
Publisher: IEEE
 
» A Bayesian Approach for Nonlinear Equalization and Signal Detection in Millimeter-Wave Communications
Abstract:
For the emerging 5G millimeter-wave communications, the nonlinearity is inevitable due to RF power amplifiers of the enormous bandwidth operating in extremely high frequency, which, in collusion with frequency-selective propagations, may pose great challenges to signal detections. In contrast to classical schemes, which calibrate nonlinear distortions in transmitters, we suggest a nonlinear equalization algorithm, with which the multipath channel and unknown symbols contaminated by nonlinear distortions and multipath interferences are estimated in receiver-ends. Attributed to the nonlinearity and marginal integration, the involved posterior density is analytically intractable and, unfortunately, most existing linear equalization schemes may become invalid. To solve this problem, the Monte-Carlo sequential importance sampling based particle filtering is suggested, and the non-analytical distribution is approximated numerically by a group of random measures with the evolving probability-mass. By applying the Taylor's series expansion technique, a local-linearization observation model is further constructed to facilitate the practical design of a sequential detector. Thus, the unknown symbols are detected recursively as new observations arrive. Simulation results validate the proposed joint detection scheme. By excluding transmitting pre-distortion of high complexity, the presented algorithm is specially designed for the receiver-end, which provides a promising framework to nonlinear equalization and signal detection in millimeter-wave communications.
Autors: Li, B.;Zhao, C.;Sun, M.;Zhang, H.;Zhou, Z.;Nallanathan, A.;
Appeared in: IEEE Transactions on Wireless Communications
Publication date: Jul 2015, volume: 14, issue:7, pages: 3794 - 3809
Publisher: IEEE
 
» A Bayesian Overlapping Coalition Formation Game for Device-to-Device Spectrum Sharing in Cellular Networks
Abstract:
We consider the spectrum sharing problem between a set of device-to-device (D2D) links and multiple co-located cellular networks. Each cellular network is controlled by an operator which can provide service to a number of subscribers. Each D2D link can either access a sub-band occupied by a cellular subscriber or obtain an empty sub-band for its exclusive use. We introduce a new spectrum sharing mode for D2D communications in cellular networks by allowing two or more D2D links with exclusive use of sub-bands to share their sub-bands with each other without consulting the operators. We establish a new game theoretic model called Bayesian non-transferable utility overlapping coalition formation (BOCF) game. We show that our proposed game can be used to model and analyze the above spectrum sharing problem. However, we observe that the core of the BOCF game can be empty, and we derive a sufficient condition for which the core is non-empty. We propose a hierarchical matching algorithm which can detect whether the sufficient condition is satisfied and, if it is satisfied, achieve a stable and unique matching structure which coincides with the overlapping coalition agreement profile in the core of the BOCF game.
Autors: Xiao, Y.;Chen, K.;Yuen, C.;Han, Z.;DaSilva, L.A.;
Appeared in: IEEE Transactions on Wireless Communications
Publication date: Jul 2015, volume: 14, issue:7, pages: 4034 - 4051
Publisher: IEEE
 
» A BDD-Based Approach for Designing Maximally Permissive Deadlock Avoidance Policies for Complex Resource Allocation Systems
Abstract:
In order to develop a computationally efficient implementation of the maximally permissive deadlock avoidance policy (DAP) for complex resource allocation systems (RAS), a recent approach focuses on the identification of a set of critical states of the underlying RAS state-space, referred to as minimal boundary unsafe states. The availability of this information enables an expedient one-step-lookahead scheme that prevents the RAS from reaching outside its safe region. The work presented in this paper seeks to develop a symbolic approach, based on binary decision diagrams (BDDs), for efficiently retrieving the (minimal) boundary unsafe states from the underlying RAS state-space. The presented results clearly demonstrate that symbolic computation enables the deployment of the maximally permissive DAP for complex RAS with very large structure and state-spaces with limited time and memory requirements. Furthermore, the involved computational costs are substantially reduced through the pertinent exploitation of the special structure that exists in the considered problem.
Autors: Fei, Z.;Reveliotis, S.;Miremadi, S.;Akesson, K.;
Appeared in: IEEE Transactions on Automation Science and Engineering
Publication date: Jul 2015, volume: 12, issue:3, pages: 990 - 1006
Publisher: IEEE
 
» A Bianisotropic Metasurface With Resonant Asymmetric Absorption
Abstract:
In this paper, we propose, design, theoretically study, and experimentally test a simple periodical array which provides perfect absorptivity when one of its surfaces is illuminated and controllable reflectivity for illuminations of the other side. The proposed structure does not contain any ground plane and relies on the bianisotropic properties of the unit cells forming the absorbing layer. The absence of the ground plane makes the new design suitable for applications where the absorber should not block transmission outside the absorption band. The proposed structure is realized as an array of nonidentical conducting patches imprinted on the two sides of a thin dielectric slab. This ultra-thin ( , where is the operational wavelength) metasurface absorber is optimized, fabricated, and tested. The test results confirm nearly perfect absorption (from one direction) and controllable reflection (from the other direction) at the resonance frequency, as well as partial transparency outside of the absorption band.
Autors: Yazdi, M.;Albooyeh, M.;Alaee, R.;Asadchy, V.;Komjani, N.;Rockstuhl, C.;R.Simovski, C.;Tretyakov, S.;
Appeared in: IEEE Transactions on Antennas and Propagation
Publication date: Jul 2015, volume: 63, issue:7, pages: 3004 - 3015
Publisher: IEEE
 
» A Bilevel Analytical Model for Dynamic Storage Pricing in a Supply Hub in Industrial Park (SHIP)
Abstract:
A Supply Hub in Industrial Park (SHIP) is a third-party business entity that leases storage space and logistics services among manufacturers located in the same industrial park. Manufacturers may hire warehouses outside the park if SHIP's storage price is exorbitant. This paper discusses how SHIP and manufacturers interact to optimize their decisions on storage pricing, replenishment, and delivery. A dynamic storage pricing strategy depending on storage length is adopted. This problem is modeled as a bilevel program where the SHIP is the leader and manufacturers are followers. Based on further assumptions, the proposed bilevel model is solved in closed-form. A series of sensitivity analyses are conducted to examine the influences of major cost parameters. The results show that SHIP's delivery charge has little impact on the total cost of large manufacturers, and its increase will not always bring profit improvement to SHIP. Contrary to intuition, the SHIP could attract more space demands from large manufacturers when charging higher in delivery or when the public warehouse's delivery charge is lower, and more space demands from small manufacturers when the market storage price is lower.
Autors: Qiu, X.;Huang, G.Q.;Lam, J.S.L.;
Appeared in: IEEE Transactions on Automation Science and Engineering
Publication date: Jul 2015, volume: 12, issue:3, pages: 1017 - 1032
Publisher: IEEE
 
» A Bridgeless BHB ZVS-PWM AC–AC Converter for High-Frequency Induction Heating Applications
Abstract:
A new prototype of a zero voltage soft-switching (ZVS) utility frequency ac to high-frequency ac resonant power converter for induction heating (IH) applications is presented in this paper. The series resonant ac–ac converter proposed herein can process the frequency conversion without any diode bridge rectifier, thereby reducing the relevant conduction power losses. In addition, power factor correction (PFC) can be naturally achieved by the inductor-based boost half-bridge circuit with the nonsmoothed dc-link. The operation principle together with an IH load power regulation scheme is described, and the converter performances including ZVS operations and PFC are demonstrated in an experiment with a 3.0-kW–30-kHz prototype by comparing it with the previously developed converter. Finally, the feasibility of the proposed ac–ac converter is evaluated from a practical point of view.
Autors: Mishima, T.;Nakagawa, Y.;Nakaoka, M.;
Appeared in: IEEE Transactions on Industry Applications
Publication date: Jul 2015, volume: 51, issue:4, pages: 3304 - 3315
Publisher: IEEE
 
» A Broadband 1-to- Power Divider/Combiner With Isolation and Reflection Cancellation
Abstract:
A novel 1-to- N broadband “ iπ-wave” power divider/combiner with reflection cancellation is presented and demonstrated. The new iπ-wave structure provides reflection cancellation and output port isolation with 1-to- N (arbitrary N) signal splitting or N-to-1 summing. It has low loss due to its use of low-impedance transmission lines and provides a relative bandwidth of 50%-200%. The concept is studied theoretically and demonstrated experimentally with several 1-to-4 dividers. The divider/combiner pair provides power amplifiers with broadband operation and well-matched input/output impedances. The concept can be implemented in hybrid circuits or monolithic microwave integrated circuits (MMICs).
Autors: Darwish, A.M.;Ibrahim, A.A.;Qiu, J.X.;Viveiros, E.;Hung, H.A.;
Appeared in: IEEE Transactions on Microwave Theory and Techniques
Publication date: Jul 2015, volume: 63, issue:7, pages: 2253 - 2263
Publisher: IEEE
 
» A Broadband 1-to- Power Divider/Combiner With Isolation and Reflection Cancellation
Abstract:
A novel 1-to- broadband “ -wave” power divider/combiner with reflection cancellation is presented and demonstrated. The new -wave structure provides reflection cancellation and output port isolation with 1-to- (arbitrary ) signal splitting or -to-1 summing. It has low loss due to its use of low-impedance transmission lines and provides a relative bandwidth of 50%–200%. The concept is studied theoretically and demonstrated experimentally with several 1-to-4 dividers. The divider/combiner pair provides power amplifiers with broadband operation and well-matched input/output impedances. The concept can be implemented in hybrid circuits or monolithic microwave integrated circuits (MMICs).
Autors: Darwish, A.M.;Ibrahim, A.A.;Qiu, J.X.;Viveiros, E.;Hung, H.A.;
Appeared in: IEEE Transactions on Microwave Theory and Techniques
Publication date: Jul 2015, volume: 63, issue:7, pages: 2253 - 2263
Publisher: IEEE
 
» A Capacity-Achieving Simple Decoder for Bias-Based Traitor Tracing Schemes
Abstract:
We investigate alternative suspicion functions for bias-based traitor tracing schemes, and present a practical construction of a simple decoder that attains capacity in the limit of large coalition size c. We derive optimal suspicion functions in both the restricted-digit model and the combined-digit model. These functions depend on information that is usually not available to the tracer-the attack strategy or the tallies of the symbols received by the colluders. We discuss how such results can be used in realistic contexts. We study several combinations of coalition attack strategy versus suspicion function optimized against some attack (another attack or the same). In many of these combinations, the usual codelength scaling ℓ ∝ c2 changes to a lower power of c, e.g., c3/2. We find that the interleaving strategy is an especially powerful attack. The suspicion function tailored against interleaving is the key ingredient of the capacity-achieving construction.
Autors: Oosterwijk, J.-J.;Skoric, B.;Doumen, J.;
Appeared in: IEEE Transactions on Information Theory
Publication date: Jul 2015, volume: 61, issue:7, pages: 3882 - 3900
Publisher: IEEE
 
» A Carrier-Based PWM Technique for Capacitor Voltage Balancing of Single-Phase Three-Level Neutral-Point-Clamped Converters
Abstract:
In this paper, a pulsewidth-modulation (PWM) technique with neutral point capacitor voltage balancing in single-phase neutral-point-clamped converters is presented. The technique is based on the injection of a common-mode voltage signal into the sinusoidal modulating signals of the conventional carrier-based PWM. Although several strategies have been reported for such a problem by using the voltage signal injection, the proposed method is very simple with easy implementation. A set of equations is presented to demonstrate how the injected voltage signal introduces a dc component on the neutral-point current, which can be controlled in order to allow the capacitor voltages balancing.
Autors: de Freitas, I.S.;Bandeira, M.M.;Barros, L.d.M.;Jacobina, C.B.;dos Santos, E.C.;Salvadori, F.;da Silva, S.A.;
Appeared in: IEEE Transactions on Industry Applications
Publication date: Jul 2015, volume: 51, issue:4, pages: 3227 - 3235
Publisher: IEEE
 
» A Cell Classifier for RRAM Process Development
Abstract:
Devices that exhibit resistive switching are promising components for future nanoelectronics with applications ranging from emerging memory to neuromorphic computing and biosensors. In this brief, we present an algorithm for identifying switchable devices, i.e., devices that can be programmed in distinct resistive states and that change their state predictably and repeatedly in response to input stimuli. The method is based on extrapolating the statistical significance of difference in between two distinct resistive states as measured from devices subjected to standardized bias protocols. The test routine is applied on distinct elements of 32 32 resistive-random-access-memory (RRAM) crossbar arrays and yields a measure of device switchability in the form of a statistical significance -value. Ranking devices by -value shows that switchable devices are typically found in the bottom 10% and are therefore easily distinguishable from nonfunctional devices. Implementation of this algorithm dramatically cuts RRAM testing time by granting fast access to the best devices in each array, as well as yield metrics.
Autors: Gupta, I.;Serb, A.;Berdan, R.;Khiat, A.;Regoutz, A.;Prodromakis, T.;
Appeared in: IEEE Transactions on Circuits and Systems II: Express Briefs
Publication date: Jul 2015, volume: 62, issue:7, pages: 676 - 680
Publisher: IEEE
 
» A cheaper way for robocars to avoid pedestrians
Abstract:
Google's self-driving cars roam the sunny streets of Mountain View, Calif., but much of the technology that powers them has never seen the light of day. In May, attendees at the IEEE International Conference on Robotics and Automation in Seattle got a rare glimpse into what the tech giant is working on.
Autors: Harris, M.;
Appeared in: IEEE Spectrum
Publication date: Jul 2015, volume: 52, issue:7, pages: 16 - 16
Publisher: IEEE
 
» A Cleaner Energy System: Renewable Energy and Electricity Market Design [In My View]
Abstract:
The rapid growth rates for renewable energy are part of a larger policy agenda to promote a cleaner energy system. The health and environmental impacts of emissions from traditional fossil fuel technologies provide a substantial reason for changing the energy system. For the greatest part, these emission impacts are externalities that provide a justification for policy to supplement natural market forces. The idealized example of a tax on harmful emissions provides a benchmark for comparing the efficacy of various policies. The author questions the policy approach that has been chosen around the globe to reduce emission impacts and externalities by forcing renewable technologies through mandates or subsidies. The author warns that solar levelized costs for 2019 entry would be 90% more expensive in the United States than an advanced gas combined cycle plant, even with emission taxes. The author favors, instead, a better market design, through an emission tax, that would work through the market to affect production, consumption, and investment. He claims such a tax would better stimulate technological innovation in economic renewable supply and in demand-side alternatives.
Autors: Hogan, W.;
Appeared in: IEEE Power and Energy Magazine
Publication date: Jul 2015, volume: 13, issue:4, pages: 112 - 109
Publisher: IEEE
 
» A Close Approximation of the Nonempty Buffer Probability Over Nakagami- Fading Channels
Abstract:
Based on the effective capacity model, the tail probability of backlog size in a wireless communication system can be characterized by two effective capacity functions, namely, the QoS exponent and the nonempty buffer probability. The QoS exponent is well understood in the literature; however, there is little known about the other function, i.e., the nonempty buffer probability, because this function has not been exactly derived. In this letter, we derive a new approximation formula for this function over Nakagami- fading channels. Simulation results indicate that our formula can closely approximate this function and is more accurate than existing approximation formulae.
Autors: Chen, Y.;Darwazeh, I.;
Appeared in: IEEE Communications Letters
Publication date: Jul 2015, volume: 19, issue:7, pages: 1121 - 1124
Publisher: IEEE
 
» A CMOS Delta-Sigma PLL Transmitter with Efficient Modulation Bandwidth Calibration
Abstract:
A delta-sigma phase locked loop (PLL) transmitter with an efficient modulation bandwidth calibration technique is proposed in this paper. With the proposed technique, the digital-analog mismatch between digital pre-emphasis filter and PLL is calibrated. The loop filter variation is tracked in the first place, and then the variation of the loop gain is calibrated by sensing the magnitude differences of the modulator between DC and ten times of the loop bandwidth. The proposed transmitter has been implemented in 0.18- CMOS technology for GSM/GPRS application. Measurement results show that the maximum RMS phase error of the proposed transmitter is 0.8 . In addition, the measured calibration accuracies for and loop gain variations are 0.5% and 0.8%, respectively. By reusing the PLL locking time, 18- calibration time is achieved. Moreover, most parts of the calibration circuitries can be shared with the receiver chain, reducing the circuit complexity overhead.
Autors: Huang, M.;Chen, D.;Guo, J.;Ye, H.;Xu, K.;Liang, X.;Lu, Y.;
Appeared in: IEEE Transactions on Circuits and Systems I: Regular Papers
Publication date: Jul 2015, volume: 62, issue:7, pages: 1716 - 1725
Publisher: IEEE
 
» A Code Generation Framework for Targeting Optimized Library Calls for Multiple Platforms
Abstract:
Directive-based programming approaches such as OpenMP and OpenACC have gained popularity due to their ease of programming. These programming models typically involve adding compiler directives to code sections such as loops in order to parallelize them for execution on multicore CPUs or GPUs. However, one problem with this approach is that existing compilers generate code directly from the annotated sections and do not make use of hardware-specific architectural features. As a result, the generated code is unable to fully exploit the capabilities of the underlying hardware. Alternatively, we propose a code generation framework in which linear algebraic operations in the annotated codes are recognized, extracted and mapped to optimized vendor-provided platform-specific library calls. We demonstrate that such an approach can result in better performance in the generated code compared to those which are generated by existing compilers. This is substantiated by experimental results on multicore CPUs and GPUs.
Autors: Wen Jun Tan;Wai Teng Tang;Goh, R.S.M.;Turner, S.J.;Weng-Fai Wong;
Appeared in: IEEE Transactions on Parallel and Distributed Systems
Publication date: Jul 2015, volume: 26, issue:7, pages: 1789 - 1799
Publisher: IEEE
 
» A Comparison of Field and Current-Driven Hot-Carrier Reliability in NPN SiGe HBTs
Abstract:
We investigate and compare the hot-carrier degradation of SiGe HBTs under both traditional mixed-mode electrical stress conditions and high-current electrical stress conditions using measured stress data and an in-depth analysis of the underlying degradation mechanisms. While large electric fields are the driving force in mixed-mode hot-carrier degradation, the Auger recombination process is shown to be the hot-carrier source under high-current stress conditions. Auger hot-carrier degradation shows a positive temperature dependence, unlike mixed-mode degradation, due to the temperature dependence of Auger recombination and its energy distribution function. We also use calibrated TCAD simulations to explain an unexpected stress threshold behavior that occurs due to the formation of a potential well in the neutral base region, and to explore a field-compression effect at the collector/subcollector junction that contributes to trap formation at the shallow trench isolation oxide interface.
Autors: Wier, B.R.;Raghunathan, U.S.;Chakraborty, P.S.;Yasuda, H.;Menz, P.;Cressler, J.D.;
Appeared in: IEEE Transactions on Electron Devices
Publication date: Jul 2015, volume: 62, issue:7, pages: 2244 - 2250
Publisher: IEEE
 
» A Comparison of SVM and GMM-Based Classifier Configurations for Diagnostic Classification of Pulmonary Sounds
Abstract:
Goal: The aim of this study is to find a useful methodology to classify multiple distinct pulmonary conditions including the healthy condition and various pathological types, using pulmonary sounds data. Methods: Fourteen-channel pulmonary sounds data of 40 subjects (healthy and pathological, where the pathologies are of obstructive and restrictive types) are modeled using a second order 250-point vector autoregressive model. The estimated model parameters are fed to support vector machine and Gaussian mixture model (GMM) classifiers which are used in various configurations, resulting in eight different methodologies in total. Results: Among the eight methodologies, the hierarchical GMM classifier yields the best performance with a total correct classification rate of 85%, where the term hierarchical refers here to first classifying the data into healthy and pathological classes, then the pathological class into obstructive and restrictive types. Both the sensitivity and specificity for the healthy versus pathological classification at the first stage of hierarchy are 90%. Conclusion: The newly proposed methodologies provide improved results compared to the previous study. The hierarchical framework is suggested for diagnostic classification of pulmonary sounds, although the algorithms are still open for further improvements. Significance: This study proposes new methodologies for diagnostic classification of pulmonary sounds, and suggests using a hierarchical framework for the first time.
Autors: Sen, I.;Saraclar, M.;Kahya, Y.P.;
Appeared in: IEEE Transactions on Biomedical Engineering
Publication date: Jul 2015, volume: 62, issue:7, pages: 1768 - 1776
Publisher: IEEE
 
» A Complete Color Normalization Approach to Histopathology Images Using Color Cues Computed From Saturation-Weighted Statistics
Abstract:
Goal: In digital histopathology, tasks of segmentation and disease diagnosis are achieved by quantitative analysis of image content. However, color variation in image samples makes it challenging to produce reliable results. This paper introduces a complete normalization scheme to address the problem of color variation in histopathology images jointly caused by inconsistent biopsy staining and nonstandard imaging condition. Method : Different from existing normalization methods that either address partial cause of color variation or lump them together, our method identifies causes of color variation based on a microscopic imaging model and addresses inconsistency in biopsy imaging and staining by an illuminant normalization module and a spectral normalization module, respectively. In evaluation, we use two public datasets that are representative of histopathology images commonly received in clinics to examine the proposed method from the aspects of robustness to system settings, performance consistency against achromatic pixels, and normalization effectiveness in terms of histological information preservation. Results: As the saturation-weighted statistics proposed in this study generates stable and reliable color cues for stain normalization, our scheme is robust to system parameters and insensitive to image content and achromatic colors. Conclusion: Extensive experimentation suggests that our approach outperforms state-of-the-art normalization methods as the proposed method is the only approach that succeeds to preserve histological information after normalization. Significance: The proposed color normalization solution would be useful to mitigate effects of color variation in pathology images on subsequent quantitative analysis.
Autors: Li, X.;Plataniotis, K.N.;
Appeared in: IEEE Transactions on Biomedical Engineering
Publication date: Jul 2015, volume: 62, issue:7, pages: 1862 - 1873
Publisher: IEEE
 
» A Comprehensive Evaluation of Common Python Implementations
Abstract:
Python is a widely used general-purpose dynamic language. Owing to its popularity, many implementations exist for the two distinct Python 2 and Python 3 language versions. Researchers evaluated seven implementations of both language versions to facilitate the selection of one of them. For this purpose, they carefully selected 523 programs to execute in each implementation. They evaluated run-time performance and memory consumption and investigated each implementation's important qualitative characteristics.
Autors: Redondo, Jose Manuel;Ortin, Francisco;
Appeared in: IEEE Software
Publication date: Jul 2015, volume: 32, issue:4, pages: 76 - 84
Publisher: IEEE
 
» A Compressive Sensing Approach to Describe Indoor Scenes for Blind People
Abstract:
This paper introduces a new portable camera-based method for helping blind people to recognize indoor objects. Unlike state-of-the-art techniques, which typically perform the recognition task by limiting it to a single predefined class of objects, we propose here a completely different alternative scheme, defined as coarse description. It aims at expanding the recognition task to multiple objects and, at the same time, keeping the processing time under control by sacrificing some information details. The benefit is to increment the awareness and the perception of a blind person to his direct contextual environment. The coarse description issue is addressed via two image multilabeling strategies which differ in the way image similarity is computed. The first one makes use of the Euclidean distance measure, while the second one relies on a semantic similarity measure modeled by means of Gaussian process estimation. To achieve fast computation capability, both strategies rely on a compact image representation based on compressive sensing. The proposed methodology was assessed on two indoor datasets representing different indoor environments. Encouraging results were achieved in terms of both accuracy and processing time.
Autors: Mekhalfi, M.L.;Melgani, F.;Bazi, Y.;Alajlan, N.;
Appeared in: IEEE Transactions on Circuits and Systems for Video Technology
Publication date: Jul 2015, volume: 25, issue:7, pages: 1246 - 1257
Publisher: IEEE
 
» A Continuous-Time Delta-Sigma Modulator for Biomedical Ultrasound Beamformer Using Digital ELD Compensation and FIR Feedback
Abstract:
This paper presents the design of a continuous-time modulator (CTDSM) to be used in an ultrasound beamformer for biomedical imaging. To achieve better resolution, the prototype modulator operates at 1.2 GHz. It incorporates a digital excess loop delay (ELD) compensation to replace the active adder in front of the internal quantizer. A digitally controlled reference-switching matrix, combined with the data-weighted averaging (DWA) technique, results in a delay-free feedback path. A multi-bit FIR feedback DAC, along with its compensation path, is used to achieve lower clock jitter sensitivity and better loop filter linearity. The modulator achieves 79.4 dB dynamic range, 77.3 dB SNR, and 74.3 dB SNDR over a 15 MHz signal bandwidth. Fabricated in a 65 nm CMOS process, the core modulator occupies an area of only 0.16 and dissipates 6.96 mW from a 1 V supply. A 58.6 fJ/conversion-step figure of merit is achieved.
Autors: Zhang, Y.;Chen, C.-H.;He, T.;Temes, G.C.;
Appeared in: IEEE Transactions on Circuits and Systems I: Regular Papers
Publication date: Jul 2015, volume: 62, issue:7, pages: 1689 - 1698
Publisher: IEEE
 
» A Cooperative Uplink Transmission Technique With Improved Diversity–Multiplexing Tradeoff
Abstract:
In this paper, a new decode-and-forward (DF) cooperative scheme is presented for half-duplex uplink transmission. The technique is based on a virtual multiple-input–multiple-output (MIMO) structure formed by the single-antenna source and relay nodes along with a multiantenna destination node. The new technique aims at providing increased diversity and multiplexing gains, contrary to existing approaches in which increased diversity gain is achieved at the cost of severe multiplexing gain loss. Furthermore, the proposed scheme is extended in a doubly opportunistic manner by incorporating both multiuser diversity and relay selection diversity. Novel criteria are suggested for selecting the best transmitting user and/or the best relays at each time slot. The theoretical outage probability and the corresponding diversity–multiplexing tradeoff curve of both the proposed technique and its opportunistic extension are derived. Indicative simulations verify the theoretical results and compare the performance of the proposed technique with the performance of existing cooperative schemes and of the noncooperative single-input–multiple-output (SIMO) system.
Autors: Tsinos, C.G.;Berberidis, K.;
Appeared in: IEEE Transactions on Vehicular Technology
Publication date: Jul 2015, volume: 64, issue:7, pages: 2883 - 2896
Publisher: IEEE
 
» A Coordination Control Strategy of Voltage-Source-Converter-Based MTDC for Offshore Wind Farms
Abstract:
Similar to other major electrical apparatuses, the reliability and stability of the dc network is becoming the most important issue when using the voltage-source-converter-based multiterminal dc (VSC-MTDC) system for offshore wind power integration. A coordinated control strategy of VSC-MTDC named master–auxiliary is proposed by combining the advantages of the voltage margin and voltage droop control. This strategy has three advantages. First, the master converter station with the constant dc voltage control can provide reference to the system dc voltage and is helpful for the stabilization of dc voltage. Second, the integrated control of the dc voltage in both master and auxiliary converter stations are helpful for providing adequate active power control (APC) and restraining large power variation. Third, the APC converter station can serve as a backup for the dc voltage control in abnormal conditions. In order to guarantee the reliability and stability of the system under various operating conditions, this paper introduces the priority of dc voltage control to the coordination control strategy. Moreover, a parameter optimizing method of controllers for this strategy is also proposed. Finally, the effectiveness of the master–auxiliary control is verified by simulations under normal and abnormal conditions.
Autors: Wang, Z.;Li, K.;Ren, J.;Sun, L.;Zhao, J.;Liang, Y.;Lee, W.;Ding, Z.;Sun, Y.;
Appeared in: IEEE Transactions on Industry Applications
Publication date: Jul 2015, volume: 51, issue:4, pages: 2743 - 2752
Publisher: IEEE
 
» A Core Compact Model for Multiple-Gate Junctionless FETs
Abstract:
A core model for multiple-gate junctionless FETs (Mug-JL-FETs) is proposed. The derived charge model is obtained via assumptions of simple potential profile for different types of Mug-JL-FETs. It was found that the linear potential approach is not accurate enough for a double-gate (DG) JL-FET, whereas it was reasonably precise for a DG inversion-mode FET. This discrepancy arises from their different operating mechanisms. Thus, the parabolic potential assumption, which is intuitively close to an actual potential profile in the Mug-FETs, was applied. As a consequence, two different formulas of the charge model in terms of depletion charges, gate capacitance, and capacitance inside the channel were found: one for a tetragonal shape of a cross-sectional channel based on a Cartesian coordinate and the other for a circular shape of a cross-sectional channel based on a cylindrical coordinate. Moreover, the proposed approach was applied for a realistically shaped channel, which is close to elliptic geometry, with a circular profile at the top and bottom parts of the channel and a rectangular profile at the center part of the channel. By applying the decoupling method reported previously, a drain current model, which is extended from the above-mentioned charge model, was also obtained.
Autors: Hur, J.;Moon, D.;Choi, J.;Seol, M.;Jeong, U.;Jeon, C.;Choi, Y.;
Appeared in: IEEE Transactions on Electron Devices
Publication date: Jul 2015, volume: 62, issue:7, pages: 2285 - 2291
Publisher: IEEE
 
» A Cross-Layer Approach for Distributed Energy-Efficient Power Control in Interference Networks
Abstract:
In contrast with existing works that rely on the same type of energy-efficiency (EE) measure to design distributed power control policies, this paper takes into account the presence of a finite packet buffer at the transmitter side and the impact of transport protocols. This approach is relevant when the transmitters have a nonzero energy cost, even when the radiated power is zero. A generalized EE performance metric integrating these features is constructed under two different scenarios in terms of transport layer protocols characterized by a constant or an adaptive packet arrival rate. The derived performance metric is shown to have several attractive properties in both scenarios, which ensures convergence of the used distributed power control algorithm to a unique point. This point is the Nash equilibrium (NE) of a game for which the equilibrium analysis is conducted. Although the equilibrium analysis methodology is not new in itself, conducting it requires several nontrivial proofs, including the proof of quasi-concavity of the payoff functions. A thorough numerical analysis is provided to illustrate the effects of the proposed approach and provides several valuable insights in terms of designing interference management policies.
Autors: Varma, V.S.;Lasaulce, S.;Hayel, Y.;Elayoubi, S.E.;
Appeared in: IEEE Transactions on Vehicular Technology
Publication date: Jul 2015, volume: 64, issue:7, pages: 3218 - 3232
Publisher: IEEE
 
» A DC Stable and Large-Time Step Well-Balanced TD-EFIE Based on Quasi-Helmholtz Projectors
Abstract:
The marching-on-in-time (MOT) solution of the time-domain electric field integral equation (TD-EFIE) has traditionally suffered from a number of issues, including the emergence of spurious static currents (dc instability) and ill-conditioning at large-time steps (low frequencies). In this contribution, a space-time Galerkin discretization of the TD-EFIE is proposed, which separates the loop and star components of both the equation and the unknown. Judiciously integrating or differentiating these components with respect to time leads to an equation which is free from dc instability. By choosing the correct temporal basis and testing functions for each of the components, a stable MOT system is obtained. Furthermore, the scaling of these basis and testing functions ensure that the system remains well conditioned for large-time steps. The loop–star decomposition is performed using quasi-Helmholtz projectors to avoid the explicit transformation to the unstable bases of loops and stars (or trees), and to avoid the search for global loops, which is a computationally expensive operation.
Autors: Beghein, Y.;Cools, K.;Andriulli, F.P.;
Appeared in: IEEE Transactions on Antennas and Propagation
Publication date: Jul 2015, volume: 63, issue:7, pages: 3087 - 3097
Publisher: IEEE
 
» A Delay-Tolerant Asynchronous Two-Way-Relay System over Doubly-Selective Fading Channels
Abstract:
We consider design of asynchronous orthogonal frequency division multiplexing (OFDM) based diamond two-way-relay (DTWR) systems in a time-varying frequency-selective (doubly-selective) fading channel. In a DTWR system, two users exchange their messages with the help of two relays. Most of the existing works on asynchronous DTWR systems assume only small relative propagation delays between the received signals at each node that do not exceed the length of the cyclic-prefix (CP). However, in certain practical communication systems, significant differences in delays may take place, and hence existing solutions requiring excessively long CPs may be highly inefficient. In this paper, we propose a delay-independent CP insertion mechanism in which the CP length depends only on the number of subcarriers and the maximum delay spread of the corresponding channels. We also propose a symbol detection algorithm that is able to tolerate very long relative delays, that even exceed the length of the OFDM block itself, without a large increase in complexity. The proposed system is shown to significantly outperform other alternatives in the literature through a number of specific examples.
Autors: Salim, A.;Duman, T.M.;
Appeared in: IEEE Transactions on Wireless Communications
Publication date: Jul 2015, volume: 14, issue:7, pages: 3850 - 3865
Publisher: IEEE
 
» A Dimmable LED Driver With Resistive DAC Feedback Control for Adaptive Voltage Regulation
Abstract:
This paper proposes a dimmable energy-efficient light-emitting diode (LED) driver for applications in interior lighting. High efficiency is achieved by an adaptive voltage regulation, which minimizes power losses in the linear current regulator. A digital control mechanism employing a resistive digital-to-analog converter for feeding the analog feedback input of a dc–dc converter is introduced. It is shown that the digital control methodology gives maximum design flexibility and enhances control over regulation speed and stability. In an experimental setup, the proposed concept is verified and evaluated. Operating at an input voltage of 24 V, the LED driver provides a relatively wide output voltage range of 3.5–38 V. Output current is regulated to 700 mA with a steady-state precision of more than 98.8%, whereas pulsewidth modulation dimming with a frequency of 1 kHz and shortest on-time of 4 is employed. A peak efficiency of the complete system of 93.9% is achieved.
Autors: Lohaus, L.;Rossius, A.;Dietrich, S.;Wunderlich, R.;Heinen, S.;
Appeared in: IEEE Transactions on Industry Applications
Publication date: Jul 2015, volume: 51, issue:4, pages: 3254 - 3262
Publisher: IEEE
 
» A Discrete-Time Direct Torque Control for Direct-Drive PMSG-Based Wind Energy Conversion Systems
Abstract:
This paper proposes a novel flux-space-vector-based direct torque control (DTC) scheme for permanent-magnet synchronous generators (PMSGs) used in variable-speed direct-drive wind energy conversion systems (WECSs). The discrete-time control law, which is derived from the perspective of flux space vectors and load angle, predicts the desired stator flux vector for the next time-step with the torque and stator flux information only. The space vector modulation (SVM) is then employed to generate the reference voltage vector, leading to a fixed switching frequency, as well as lower flux and torque ripples, when compared to the conventional DTC. Compared with other SVM-based DTC methods in the literature, the proposed DTC scheme eliminates the use of proportional–integral regulators and is less dependent on machine parameters, e.g., stator inductances and permanent-magnet flux linkage, while the main advantages of the DTC, e.g., fast dynamic response and no need of coordinate transform, are preserved. The proposed DTC scheme is applicable for both nonsalient-pole and salient-pole PMSGs. The overall control scheme is simple to implement and is robust to parameter uncertainties and variations of the PMSGs. The effectiveness of the proposed discrete-time DTC scheme is verified by simulation and experimental results on a 180-W salient-pole PMSG and a 2.4-kW nonsalient-pole PMSG used in variable-speed direct-drive WECSs.
Autors: Zhang, Z.;Zhao, Y.;Qiao, W.;Qu, L.;
Appeared in: IEEE Transactions on Industry Applications
Publication date: Jul 2015, volume: 51, issue:4, pages: 3504 - 3514
Publisher: IEEE
 
» A Dual-Band Coupled Resonator Decoupling Network for Two Coupled Antennas
Abstract:
A new decoupling scheme called dual-band coupled resonator decoupling network (CRDN) is presented. By properly designing the coupling coefficients between two pairs of coupled resonators, the network can effectively reduce the mutual couplings between two coupled dual-band antennas in two bands simultaneously. The new scheme is proved by a practical microstrip version of the device for two dual-band antennas working at 2.4 and 5.2 GHz frequency bands. A compact planar dual-band CRDN consisting of a pair of dual-band open-loop square ring resonators is proposed. The measured scattering parameters of two coupled antennas with and without the dual-band CRDN in free space (FS) and with hand phantom demonstrate that the isolation between the two antennas in both the low and high bands can be improved from 8 to 10 dB, respectively, to below 20 dB while maintaining a good matching performance. The total efficiency and envelop correlation coefficient for the decoupled antennas show a significant improvement as compared to the coupled antenna case. The proposed dual-band CRDN scheme is easy to be implemented in an integrated device, and is very attractive for practical multiple input and multiple output (MIMO) applications.
Autors: Zhao, L.;Wu, K.;
Appeared in: IEEE Transactions on Antennas and Propagation
Publication date: Jul 2015, volume: 63, issue:7, pages: 2843 - 2850
Publisher: IEEE
 
» A Dual-Mode Multi-Band Second Harmonic Controlled SOI LDMOS Power Amplifier
Abstract:
This letter presents a dual-mode multi-band second harmonic controlled SOI LDMOS power amplifier (PA). A mode selection switch is designed to have better power handing capability than a conventional switch, which improves performance in low power mode (LPM). To improve the PA's linearity in high power mode (HPM), second harmonic is controlled with the aid of a path for LPM. The PA, implemented with a 0.13- m SOI LDMOS process, operates in triple bands (band 5, 8, and 20) with dual power modes. It is measured using a 16 QAM long-term evolution (LTE) signal with a 10 MHz bandwidth. At 850 MHz, the results show 27.7 dBm average output power (Pout), 31.4 dB gain, and 31.4% power-added efficiency (PAE) with 4% error-vector magnitude (EVM) in HPM and 10.4 dB gain, 15.5 dBm Pout, and 22.5% PAE with 4% EVM in LPM with the LTE signal.
Autors: Kim, K.;Lee, D.-H.;Hong, S.;
Appeared in: IEEE Microwave and Wireless Components Letters
Publication date: Jul 2015, volume: 25, issue:7, pages: 466 - 468
Publisher: IEEE
 
» A Dual-Slope Capacitance-to-Digital Converter Integrated in an Implantable Pressure-Sensing System
Abstract:
A dual-slope capacitance-to-digital converter for pressure-sensing is presented and demonstrated in a complete microsystem. The design uses base capacitance subtraction with a configurable capacitor bank to narrow down input capacitance range and reduce conversion time. An energy-efficient iterative charge subtraction method is proposed, employing a current mirror that leverages the 3.6 V battery supply available in the system. We also propose dual-precision comparators to reduce comparator power while maintaining high accuracy during slope conversion, further improving energy efficiency. The converter occupies 0.105 mm in 180 nm CMOS and achieves 44.2 dB SNR at 6.4 ms conversion time and 110 nW of power, corresponding to 5.3 pJ/conv-step FoM. The converter is integrated with a pressure transducer, battery, processor, power management unit, and radio to form a complete 1.4 mm 2.8 mm 1.6 mm pressure sensor system aimed at implantable devices. The multi-layer system is implemented in 180 nm CMOS. The system was tested for resolution in a pressure chamber with an external 3.6 V supply and serial communication bus, and the measured resolution of 0.77 mmHg was recorded. We also demonstrated the wireless readout of the pressure data on the stack system operating completely wirelessly using an integrated battery.
Autors: Oh, S.;Lee, Y.;Wang, J.;Foo, Z.;Kim, Y.;Jung, W.;Li, Z.;Blaauw, D.;Sylvester, D.;
Appeared in: IEEE Journal of Solid-State Circuits
Publication date: Jul 2015, volume: 50, issue:7, pages: 1581 - 1591
Publisher: IEEE
 
» A Farewell to Air Gaps, Part 2
Abstract:
Air gaps have never been an effective deterrent to a determined state-sponsored aggressor. This is just one of the lessons we learned from Stuxnet and the Farewell incident, and I will describe a few others. This is the second part of a two-part series. Part 1 is in the June 2015 issue at 10.1109/MC.2015.179.
Autors: Berghel, Hal;
Appeared in: Computer
Publication date: Jul 2015, volume: 48, issue:7, pages: 59 - 63
Publisher: IEEE
 
» A Fault Detection and Tolerance Architecture for Post-Silicon Skew Tuning
Abstract:
Clock skew minimization that is an important issue in very large scale integration design has become difficult due to the presence of process, voltage, and temperature (PVT) variations. The post-silicon skew tuning (PST) technique with the ability to tolerate PVT variations, even after a chip is manufactured has generated considerable discussion. The basic idea of the PST architecture is to minimize the clock skew dynamically. Unlike most previous works that have focused on the implementation and the performance issues of a PST architecture, this paper focuses on the testing issues of a PST architecture. However, testing the variation tolerance ability of the PST architecture is difficult because the clock skew does not directly affect the functionality of a design. In this paper, we propose an efficient fault model considering the physical limitation of the devices for the PST architecture. In addition, we propose some novel structures to detect the manufacturing faults and increase the robustness of a PST architecture. Our experiment shows that with a little increase in overhead, we can achieve robustness.
Autors: Kao, M.Y.C.;Tsai, K.;Chang, S.;
Appeared in: IEEE Transactions on Very Large Scale Integration Systems
Publication date: Jul 2015, volume: 23, issue:7, pages: 1210 - 1220
Publisher: IEEE
 
» A Framework for Efficient Structured Max-Margin Learning of High-Order MRF Models
Abstract:
We present a very general algorithm for structured prediction learning that is able to efficiently handle discrete MRFs/CRFs (including both pairwise and higher-order models) so long as they can admit a decomposition into tractable subproblems. At its core, it relies on a dual decomposition principle that has been recently employed in the task of MRF optimization. By properly combining such an approach with a max-margin learning method, the proposed framework manages to reduce the training of a complex high-order MRF to the parallel training of a series of simple slave MRFs that are much easier to handle. This leads to a very efficient and general learning scheme that relies on solid mathematical principles. We thoroughly analyze its theoretical properties, and also show that it can yield learning algorithms of increasing accuracy since it naturally allows a hierarchy of convex relaxations to be used for loss-augmented MAP-MRF inference within a max-margin learning approach. Furthermore, it can be easily adapted to take advantage of the special structure that may be present in a given class of MRFs. We demonstrate the generality and flexibility of our approach by testing it on a variety of scenarios, including training of pairwise and higher-order MRFs, training by using different types of regularizers and/or different types of dissimilarity loss functions, as well as by learning of appropriate models for a variety of vision tasks (including high-order models for compact pose-invariant shape priors, knowledge-based segmentation, image denoising, stereo matching as well as high-order Potts MRFs).
Autors: Komodakis, N.;Xiang, B.;Paragios, N.;
Appeared in: IEEE Transactions on Pattern Analysis and Machine Intelligence
Publication date: Jul 2015, volume: 37, issue:7, pages: 1425 - 1441
Publisher: IEEE
 
» A Framework to Construct Three-Dimensional Complementary Codes for Multiuser MIMO Systems
Abstract:
This paper proposes a framework to construct 3-D complementary codes (3DCCs), which enable chip-level space–time coding to integrate multiantenna and multiple-access techniques in a unified platform. The 3DCCs are generated based on an extension method with the help of traditional complementary codes and well-designed matrices. The relationship between the correlation properties and flock size of the constructed 3DCCs is analyzed, and the proposed framework provides a generic way to construct different families of 3DCCs with a controllable tradeoff between their correlation properties and flock sizes. As examples, three families of 3DCCs with different characteristic features are constructed using the framework, and their correlation properties are simulated to validate their properties. The general architecture of the 3DCC-based multiple-input multiple-output (MIMO) system is also proposed in this paper. The simulated bit-error-rate (BER) performance of the corresponding system over both flat and multipath fading channels show that the constructed 3DCCs can eliminate both multiuser and multipath interferences in multiuser MIMO communications. The property to provide both transmit diversity and multiplexing with its uniquely flexible tradeoff between the two also makes it particularly well suited for futuristic wireless communications to fit to varying channel conditions and application requirements.
Autors: Sun, S.;Chen, H.;Meng, W.;
Appeared in: IEEE Transactions on Vehicular Technology
Publication date: Jul 2015, volume: 64, issue:7, pages: 2861 - 2874
Publisher: IEEE
 
» A Fully Decentralized Approach for Solving the Economic Dispatch Problem
Abstract:
A new decentralized approach for solving the economic dispatch problem is presented in this paper. The proposed approach consists of either two or three stages. In the first stage, a flooding-based consensus algorithm is proposed in order to achieve consensus among the agents with respect to the units and system data. In the second stage, a suitable algorithm is used for solving the economic dispatch problem in parallel. For cases in which a nondeterministic method is used in the second stage, a third stage is applied to achieve consensus about the final solution of the problem, with a flooding-based consensus algorithm for sharing the information required during this stage. The proposed approach is highly effective for solving the non-convex formulation of the economic dispatch problem and for incorporating transmission losses accurately in a fully decentralized manner. Three case studies that were examined for validation purposes are described. The results obtained demonstrate that the proposed approach aggregates many of the advantages of both centralized and fully decentralized mechanisms for solving the economic dispatch problem.
Autors: Elsayed, W.T.;El-Saadany, E.F.;
Appeared in: IEEE Transactions on Power Systems
Publication date: Jul 2015, volume: 30, issue:4, pages: 2179 - 2189
Publisher: IEEE
 
» A Fully Implantable Stimulator With Wireless Power and Data Transmission for Experimental Investigation of Epidural Spinal Cord Stimulation
Abstract:
Epidural spinal cord stimulation (ESCS) combined with partial weight-bearing therapy (PWBT) has been shown to facilitate recovery of functional walking for individuals after spinal cord injury (SCI). The investigation of neural mechanisms of recovery from SCI under this treatment has been conducted broadly in rodent models, yet a suitable ESCS system is still unavailable. This paper describes a practical, programmable, and fully implantable stimulator for laboratory research on rats to explore fundamental neurophysiological principles for functional recovery after SCI. The ESCS system is composed of a personal digital assistant (PDA), an external controller, an implantable pulse generator (IPG), lead extension, and stimulating electrodes. The stimulation parameters can be programmed and adjusted through a graphical user interface on the PDA. The external controller is placed on the rat back and communicates with the PDA via radio-frequency (RF) telemetry. An RF carrier from the class-E power amplifier in the external controller provides both data and power for the IPG through an inductive link. The IPG is built around a microcontroller unit to generate voltage-regulated pulses delivered to the bipolar electrode for ESCS in rats. The encapsulated IPG measures 22 mm 23 mm 7 mm with a mass of g. This fully implantable batteryless stimulator provided a simplified and efficient method to carry out chronic experiments in untethered animals for medical electro-neurological research.
Autors: Xu, Q.;Hu, D.;Duan, B.;He, J.;
Appeared in: IEEE Transactions on Neural Systems and Rehabilitation Engineering
Publication date: Jul 2015, volume: 23, issue:4, pages: 683 - 692
Publisher: IEEE
 
» A game-theoretic perspective on self-organizing optimization for cognitive small cells
Abstract:
In this article, we investigate self-organizing optimization for cognitive small cells (CSCs), which have the ability to sense the environment, learn from historical information, make intelligent decisions, and adjust their operational parameters. By exploring the inherent features, some fundamental challenges for self-organizing optimization in CSCs are presented and discussed. Specifically, the dense and random deployment of CSCs brings about some new challenges in terms of scalability and adaptation; furthermore, the uncertain, dynamic, and incomplete information constraints also impose some new challenges in terms of convergence and robustness. For providing better service to users and improving resource utilization, four requirements for self-organizing optimization in CSCs are presented and discussed. Following the attractive fact that the decisions in game-theoretic models are exactly coincident with those in self-organizing optimization (i.e., distributed and autonomous), we establish a framework of gametheoretic solutions for self-organizing optimization in CSCs and propose some featured game models. Specifically, their basic models are presented, some examples are discussed, and future research directions are given.
Autors: Xu, Y.;Wang, J.;Wu, Q.;Du, Z.;Shen, L.;Anpalagan, A.;
Appeared in: IEEE Communications Magazine
Publication date: Jul 2015, volume: 53, issue:7, pages: 100 - 108
Publisher: IEEE
 
» A GPU-Accelerated Finite-Difference Time-Domain Scheme for Electromagnetic Wave Interaction With Plasma
Abstract:
A graphical processing unit (GPU)-accelerated finite-difference time-domain (FDTD) scheme for the simulation of radio-frequency (RF) wave propagation in a dynamic, magnetized plasma is presented. This work builds on well-established FDTD techniques with the inclusion of new time advancement equations for the plasma fluid density and temperature. The resulting FDTD formulation is suitable for the simulation of the time-dependent behavior of an ionospheric plasma due to interaction with an RF wave and the excitation of plasma waves and instabilities. The stability criteria and the dependence of accuracy on the choice of simulation parameters are analyzed and found to depend on the choice of simulation grid parameters. It is demonstrated that accelerating the FDTD code using GPU technology yields significantly higher performance, with a dual-GPU implementation achieving a rate of node update almost two orders of magnitude faster than a serial implementation. Optimization techniques such as memory coalescence are demonstrated to have a significant effect on code performance. The results of numerical tests performed to validate the FDTD scheme are presented, with a good agreement achieved when the simulation results are compared to both the predictions of plasma theory and to the results of the Tech-X VORPAL 4.2.2 software that was used as a benchmark.
Autors: Cannon, P.D.;Honary, F.;
Appeared in: IEEE Transactions on Antennas and Propagation
Publication date: Jul 2015, volume: 63, issue:7, pages: 3042 - 3054
Publisher: IEEE
 
» A High Spectral Efficiency Coherent Microwave Photonic Link Employing Both Amplitude and Phase Modulation With Digital Phase Noise Cancellation
Abstract:
A high spectral efficiency coherent microwave photonic link (MPL) supporting amplitude and phase modulation incorporating a digital phase noise cancellation is proposed and experimentally demonstrated. At the transmitter, a continuous-wave light wave is amplitude- and phase-modulated by two microwave vector signals carried by a microwave carrier at an identical frequency. The modulated optical signal is polarization multiplexed with an unmodulated optical carrier and transmitted over a length of a single-mode fiber (SMF). At the receiver, the optical signal is detected coherently by a coherent receiver to which a local oscillator (LO) laser source is also applied. Through advanced digital signal processing, the microwave vector signals are recovered, and the phase noise introduced by both the transmitter laser source and LO laser source is cancelled. An experiment is performed. The transmission of a 2.5-Gb/s 16-QAM and a 1.25-Gb/s QPSK microwave vector signals both at 2.5 GHz over a 25-km SMF is implemented. The total bit rate of the MPL is 3.75 Gb/s. The transmission performance of the MPL in terms of error vector magnitudes and bit error rates is evaluated.
Autors: Chen, X.;Yao, J.;
Appeared in: Journal of Lightwave Technology
Publication date: Jul 2015, volume: 33, issue:14, pages: 3091 - 3097
Publisher: IEEE
 
» A High-Performance On-Chip Bus (MSBUS) Design and Verification
Abstract:
This brief proposes a high-performance system-on-chip bus protocol termed the master–slave bus (MSBUS). Considering the inevitable tradeoff among area, throughput and energy efficiency, the control bus is developed as a low-cost and low-power bus, and the data bus is created as a high-throughput full-duplex bus with the feature of block data transfer. To evaluate the bus performance, we create four analytical models including transfer time consumption (TC), wire efficiency (WE), valid data bandwidth (VDB) and dynamic energy efficiency. Then, the advanced high-performance bus-, advanced eXensible interface (AXI)-, and MSBUS-based direct memory access (DMA) are developed as a case study of hardware implementation. It is observed that MSBUS DMA costs less hardware resources and achieves higher performance, especially in the block transfer mode. For instance, the results from both the analytical models and the practical tests show that the TC of MSBUS is close to 63% of the AXI, the WE and VDB of MSBUS are almost 2.3 and 1.6 times of the AXI respectively, and the energy consumption is half of AXI in the block transfer mode.
Autors: Yang, X.;Andrian, J.H.;
Appeared in: IEEE Transactions on Very Large Scale Integration Systems
Publication date: Jul 2015, volume: 23, issue:7, pages: 1350 - 1354
Publisher: IEEE
 
» A Holistic Analysis of Circuit Performance Variations in 3-D ICs With Thermal and TSV-Induced Stress Considerations
Abstract:
In 3-D ICs, through silicon via (TSV)-induced thermal residual stress impacts several transistor electrical parameters—low-field mobility, saturation velocity, and threshold voltage. These thermal-stress related shifts are coupled with other temperature effects on transistor parameters that are seen even in the absence of TSVs. In this paper, analytical models are developed to holistically represent the effect of thermally-induced variations on circuit timing. A biaxial stress model is built, based on a superposition of 2-D axisymmetric and Boussinesq-type elasticity models. The computed stresses and strains are then employed to evaluate transistor mobility, saturation velocity, and threshold voltage. The electrical variations are translated into gate-level delay and leakage power calculations, which are then elevated to circuit-level analysis to thoroughly evaluate the variations in circuit performance-induced by TSV stress.
Autors: Marella, S.K.;Sapatnekar, S.S.;
Appeared in: IEEE Transactions on Very Large Scale Integration Systems
Publication date: Jul 2015, volume: 23, issue:7, pages: 1308 - 1321
Publisher: IEEE
 
» A Hotness Filter of Files for Reliable Non-Volatile Memory Systems
Abstract:
Flash memory has been widely utilized in embedded systems and consumer electronics, because of its low-power consumption, high-performance access, non-volatility, and shock resistance. A flash-memory device is different from a typical hard-disk device and requires a sophisticated management method to improve the reliable endurance and provide the efficient storage management. To improve the reliable endurance and provide the efficient storage management, the previous works have demonstrated that the identification of the frequently used data and the least recently used data is a key point. In this paper, we will propose a hotness filter of files to calculate how the files are accessed (i.e., reads and writes) intensively. The proposed filter is designed specifically to distinguish between hot and cold files by considering the characteristics of non-volatile memory systems and Android systems. In the experiments, we have implemented the hotness filter in a real Android system (e.g., Asus Nexus 7) and demonstrated that the proposed filter can correctly identify hot and cold files without significant overhead.
Autors: Wu, C.;Wu, P.;Chen, K.;Chang, W.;Lai, K.;
Appeared in: IEEE Transactions on Dependable and Secure Computing
Publication date: Jul 2015, volume: 12, issue:4, pages: 375 - 386
Publisher: IEEE
 
» A Hybrid Brain–Computer Interface Based on the Fusion of P300 and SSVEP Scores
Abstract:
The present study proposes a hybrid brain–computer interface (BCI) with 64 selectable items based on the fusion of P300 and steady-state visually evoked potential (SSVEP) brain signals. With this approach, row/column (RC) P300 and two-step SSVEP paradigms were integrated to create two hybrid paradigms, which we denote as the double RC (DRC) and 4-D spellers. In each hybrid paradigm, the target is simultaneously detected based on both P300 and SSVEP potentials as measured by the electroencephalogram. We further proposed a maximum-probability estimation (MPE) fusion approach to combine the P300 and SSVEP on a score level and compared this approach to other approaches based on linear discriminant analysis, a naïve Bayes classifier, and support vector machines. The experimental results obtained from thirteen participants indicated that the 4-D hybrid paradigm outperformed the DRC paradigm and that the MPE fusion achieved higher accuracy compared with the other approaches. Importantly, 12 of the 13 participants, using the 4-D paradigm achieved an accuracy of over 90% and the average accuracy was 95.18%. These promising results suggest that the proposed hybrid BCI system could be used in the design of a high-performance BCI-based keyboard.
Autors: Yin, E.;Zeyl, T.;Saab, R.;Chau, T.;Hu, D.;Zhou, Z.;
Appeared in: IEEE Transactions on Neural Systems and Rehabilitation Engineering
Publication date: Jul 2015, volume: 23, issue:4, pages: 693 - 701
Publisher: IEEE
 
» A Hybrid Mobile Visual Search System With Compact Global Signatures
Abstract:
Mobile visual search systems typically compare a query image against a database of annotated images for accurate object recognition. On-server database matching can search a large database hosted in the cloud, but the query latency could suffer with slow network transmissions or server congestion . On-device database matching can ensure fast recognition responses regardless of network or server conditions , but a small amount of memory on the mobile device can severely limit the number of images that can be stored in an on- device database. This paper presents a new hybrid system that combines the advantages of on-device and on-server database matching. At the core of this system, we first develop a compact and discriminative global signature to characterize each image. Our global signature uses an optimized local feature count that is derived from a statistical analysis of the retrieval performance . We additionally create two extensions that exploit color information within images and relationships between similar database images to improve retrieval accuracy. Then, we propose methods for efficient interframe coding of a sequence of global signatures which are extracted from the viewfinder frames on the mobile device. A low bitrate stream of global signatures can be sent to the server at an uplink bitrate of less than 2 kbps to broaden the search range of the current query and to update the on-device database to help future queries.
Autors: Chen, D.M.;Girod, B.;
Appeared in: IEEE Transactions on Multimedia
Publication date: Jul 2015, volume: 17, issue:7, pages: 1019 - 1030
Publisher: IEEE
 
» A hybrid transducer to evaluate stomach emptying by ultrasound and susceptometric measurements: an in vivo feasibility study
Abstract:
Gastric emptying reflects a diversity of important physiological functions. Alternating current biosusceptometry (ACB) is an inexpensive, radiation-free, and minimally invasive method to evaluate gastric emptying, but its response depends on the spatial distribution of the magnetized material and does not provide precise anatomical information. The hybrid transducer, which combines ACB and an ultrasound probe, is an alternative to improve susceptometry measurements, namely the spatial localization of the magnetized source. In this study, initial stomach emptying, in rats, was monitored with the aid of the hybrid transducer. Yogurt mixed with ferrite particles was injected into the rat???s stomach. The hybrid transducer was placed on the rat???s abdomen during experiments, and the susceptometry signal and magnetomotive ultrasound (MMUS) images were saved and postprocessed. MMUS highlighted the movement of magnetic particles due to magnetic force from ACB excitation coils, and showed the rat???s stomach location. In this feasibility study, we monitored the stomach emptying of 4 rats for 20 min. The mean relative ACB signal decayed by 4.6 ?? 0.1%, and the mean relative area of MMUS images decreased by 4.5 ?? 0.2%, after 20 min postingestion of the magnetic meal due to stomach emptying. In a second experiment, 3-D MMUS images from axial sequences were obtained by spatially translating the hybrid transducer, providing details of the stomach wall, which may enable minimally invasive detection of abnormalities. In conclusion, the MMUS image increased ACB spatial resolution and furnished additional anatomical information.
Autors: Bruno, A.C.;Sampaio, D.R.T.;Pavan, T.Z.;Baffa, O.;Carneiro, A.A.O.;
Appeared in: IEEE Transactions on Ultrasonics, Ferroelectrics and Frequency Control
Publication date: Jul 2015, volume: 62, issue:7, pages: 1288 - 1294
Publisher: IEEE
 
» A Hybrid-Domain Two-Step Time-to-Digital Converter Using a Switch-Based Time-to-Voltage Converter and SAR ADC
Abstract:
In this brief, an energy-efficient time-to-digital converter (TDC) using a hybrid of time- and voltage-domain circuits is presented. The proposed TDC operates in two steps, i.e., first in the time domain by using a delay-line TDC and then in the voltage domain by using a successive-approximation-register analog-to-digital converter. The time residue of the first stage is converted to voltage by using a switch-based time-to-voltage converter (TVC) that eliminates the need for a current source with large output impedance. To improve the linearity of the proposed TVC, pseudodifferential time-domain signaling is presented. A prototype chip fabricated in the 65-nm CMOS achieves 630 fs of time resolution at 120 megasamples/s while consuming 3.7 mW from a 1.2-V supply. The figure of merit is 244 fJ/conversion-step, which is the best among the recently published high-speed TDCs.
Autors: Kim, J.;Kim, Y.;Kim, K.;Yu, W.;Cho, S.;
Appeared in: IEEE Transactions on Circuits and Systems II: Express Briefs
Publication date: Jul 2015, volume: 62, issue:7, pages: 631 - 635
Publisher: IEEE
 
» A Hypergraph-Based Reduction for Higher-Order Binary Markov Random Fields
Abstract:
Higher-order Markov Random Fields, which can capture important properties of natural images, have become increasingly important in computer vision. While graph cuts work well for first-order MRF’s, until recently they have rarely been effective for higher-order MRF’s. Ishikawa’s graph cut technique [1], [2] shows great promise for many higher-order MRF’s. His method transforms an arbitrary higher-order MRF with binary labels into a first-order one with the same minima. If all the terms are submodular the exact solution can be easily found; otherwise, pseudoboolean optimization techniques can produce an optimal labeling for a subset of the variables. We present a new transformation with better performance than [1], [2], both theoretically and experimentally. While [1], [2] transforms each higher-order term independently, we use the underlying hypergraph structure of the MRF to transform a group of terms at once. For binary variables, each of which appears in terms with other variables, at worst we produce non-submodular terms, while [1], [2] produces O(-
k) . We identify a local completeness property under which our method perform even better, and show that under certain assumptions several important vision problems (including common variants of fusion moves) have this property. We show experimentally that our method produces smaller weight of non-submodular edges, and that this metric is directly related to the effectiveness of QPBO [3]. Running on the same field of experts dataset used in [1], [2] we optimally label significantly more variables (96 versus 80 percent) and converge more rapidly to a lower energy. Preliminary experiments suggest that some other higher-order MRF’s used in stereo [4] and segmentation [5] are also locally complete and would thus benefit from our work.
Autors: Fix, A.;Gruber, A.;Boros, E.;Zabih, R.;
Appeared in: IEEE Transactions on Pattern Analysis and Machine Intelligence
Publication date: Jul 2015, volume: 37, issue:7, pages: 1387 - 1395
Publisher: IEEE
 

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