Electrical and Electronics Engineering publications abstract of: 03-2017 sorted by title, page: 10

» Impact of Interface Trap Charges on Performance of Electrically Doped Tunnel FET With Heterogeneous Gate Dielectric
Abstract:
In this paper, we investigate for the first time effect of positive (donor) and negative (acceptor) interface trap charges on the performance of proposed heterogeneous gate dielectric (HD) electrically doped tunnel field-effect transistor (EDTFET) in terms of dc, analog/RF, and linearity distortion parameters, where the HD layer is considered as a gate dielectric to improve the ON-state current and device performance. For this, a comparative analysis has been performed between conventional and proposed EDTFET with identical dimensions in the presence of interface trap charges. ATLAS device simulation of both devices is performed for different performance metrics such as transfer characteristics, parasitic capacitances, device efficiency, output conductance (), cut-off frequency (), and gain bandwidth product. However, linearity distortion parameters of the proposed device such as third-order transconductance coefficient (), VIP2, VIP3, IIP3, and IMD3 are also investigated. The device simulations show that HD-EDTFET is more immune in terms of performance variation than conventional EDTFET with different interface trap charges available at the Si/SiO2 interface. Thus, it can be utilized as a suitable candidate for low power analog/RF applications.
Autors: Pulimamidi Venkatesh;Kaushal Nigam;Sunil Pandey;Dheeraj Sharma;Pravin N. Kondekar;
Appeared in: IEEE Transactions on Device and Materials Reliability
Publication date: Mar 2017, volume: 17, issue:1, pages: 245 - 252
Publisher: IEEE
 
» Impact of Mechanical Stress on Characteristics of Interior Permanent Magnet Synchronous Motors
Abstract:
In this paper, we investigate the impact of mechanical stress on characteristics of interior permanent magnet synchronous motors from both results of measurement and calculation. First, the basic experiments by using stator cores with/without shrink fitting of housings are carried out. The measured iron loss is compared with the calculated results obtained by combined stress and electromagnetic field finite-element analysis. Next, the measured torque and iron loss of the motor under load conditions are compared with the analysis that considers the mechanical stress caused by both the stator shrink fitting and the rotor centrifugal force. The measured and calculated results are found to be in good agreement. From these results, it is clarified that the mechanical stress causes not only an increase in the stator iron loss, but also an increase in the rotor-iron loss, and a decrease in the reluctance torque of interior permanent magnet synchronous motors.
Autors: Katsumi Yamazaki;Hidetada Takeuchi;
Appeared in: IEEE Transactions on Industry Applications
Publication date: Mar 2017, volume: 53, issue:2, pages: 963 - 970
Publisher: IEEE
 
» Impact of Recess Etching on the Temperature-Dependent Characteristics of GaN-Based MIS-HEMTs With Al2O3/AlN Gate-Stack
Abstract:
This paper studied the recess-etching effects on the temperature-dependent characteristics of AlGaN/GaN metal-insulator-semiconductor high-electron-mobility transistors (MIS-HEMTs) with Al2O3/AlN gate-stack. The 12.6 nm recess-etching resulted in voltage shift of capacitance-voltage curves by 2.4 V, improved peak field-effect mobility ( from 1906 to 2036 cm2/, and increased peak transconductance ( from 272 to 353 mS/mm. The temperature-dependent measu-rement from 298 to 473 K showed decrease in maximum drain current, , and for both devices with and without recess etching, attributed to thermal electron emission and carrier depletion effects. Recess etching did not degrade the thermal stability of carrier distribution and the transport properties. Temperature-dependent analysis revealed that optical phonon scattering dominated the transport mechanism of Al2O3/AlN/ AlGaN/GaN MIS-HEMTs. Optical phonon energy of 74 and 77 meV were obtained for the devices with and without recess etching, respectively.
Autors: Jiejie Zhu;Qing Zhu;Lixiang Chen;Bin Hou;Ling Yang;Xiaowei Zhou;Xiaohua Ma;Yue Hao;
Appeared in: IEEE Transactions on Electron Devices
Publication date: Mar 2017, volume: 64, issue:3, pages: 840 - 847
Publisher: IEEE
 
» Impact of Short-Wavelength and Long-Wavelength Line-Edge Roughness on the Variability of Ultrascaled FinFETs
Abstract:
We examine the impact of line-edge roughness (LER) on the variability in the on-current and saturation threshold voltage of ultrascaled FinFET devices via quantum-mechanical transport simulation. We obtain a realistic model of LER by decomposing the LER into short- and long- fluctuations, and we consider their separate influences on device performance. We show that the long- fluctuations lead to greater device variability than the short- fluctuations, and we explain the difference between the two cases via the influence of fluctuating quantum confinement arising from the LER. Finally, we consider devices in which the long- fluctuations of the two fin edges are correlated and demonstrate that this correlation significantly improves the variability. Thus, we show the continued need for fabrication technology either to reduce the amplitude of the long- fluctuations or to ensure the long- fluctuations between the sidewalls of ultrascaled FinFET devices are correlated.
Autors: Michael Wong;Kyle D. Holland;Sam Anderson;Shahriar Rizwan;Zhi Cheng Jason Yuan;Terence B. Hook;Diego Kienle;Prasad S. Gudem;Mani Vaidyanathan;
Appeared in: IEEE Transactions on Electron Devices
Publication date: Mar 2017, volume: 64, issue:3, pages: 1231 - 1238
Publisher: IEEE
 
» Impact of Silicon Nitride Stoichiometry on the Effectiveness of AlGaN/GaN HEMT Field Plates
Abstract:
Field plate (FP) control of current collapse and channel electric field distribution in AlGaN/GaN High Electron Mobility Transistors is investigated as a function of low-pressure chemical vapor deposition silicon-nitride stoichiometry. Dependence of current collapse is seen, however, this also leads to enhanced FP pinchoff voltages and higher leakage. Electric field concentration at the gate edge is indicated by measuring OFF-state Two dimensional electron gas position with a sense contact technique. A model explaining the FP threshold variation due to barrier leakage is proposed.
Autors: William M. Waller;Mark Gajda;Saurabh Pandey;Johan J. T. M. Donkers;David Calton;Jeroen Croon;Serge Karboyan;Jan Šonský;Michael J. Uren;Martin Kuball;
Appeared in: IEEE Transactions on Electron Devices
Publication date: Mar 2017, volume: 64, issue:3, pages: 1197 - 1202
Publisher: IEEE
 
» Impact of Soft Magnetic Material on Design of High-Speed Permanent-Magnet Machines
Abstract:
This paper investigates the effect of two soft magnetic materials on a high-speed machine design, namely, 6.5% silicon steel and cobalt–iron alloy. The effect of design parameters on the machine performance as an aircraft starter-generator is analyzed. The material properties which include B-H characteristics and the losses are obtained at different frequencies under an experiment and used to predict the machine performance accurately. In the investigation presented in this paper, it is shown that machines designed with 6.5% silicon steel at a high core flux density has lower weight and lower losses than the cobalt–iron alloy designs. This is mainly due to the extra weight contributed by the copper content especially in the end-windings. Due to the high operating frequencies, the core losses in the cobalt–iron machine designs are found to outweigh the copper losses incurred in the silicon steel machines. It is also shown that change in stack length/number of turns has a considerable effect on the copper losses at starting, however has no significant advantage on rated efficiency which happens to be in a field-weakening operating point. It is also shown that the performance of the machine designs depends significantly on material selection and the operating point of the core. The implications of the variation of design parameters on the machine performance is discussed and provide insight into the influence of parameters that effect overall power density.
Autors: Nuwantha Fernando;Gaurang Vakil;Puvan Arumugam;Emmanuel Amankwah;Chris Gerada;Serhiy Bozhko;
Appeared in: IEEE Transactions on Industrial Electronics
Publication date: Mar 2017, volume: 64, issue:3, pages: 2415 - 2423
Publisher: IEEE
 
» Impact of Ti Content on Structural and Electrical Characteristics of High- $kappa$ Yb2TiO5 $alpha$ -InZnSnO Thin-Film Transistors
Abstract:
In this letter, we investigated the impact of Ti content on structural properties and electrical characteristics of high- Yb2TiO5 gate dielectrics for amorphous indium–zinc–tin-oxide (-IZTO) thin-film transistor (TFT) devices. The Yb2TiO5 -IZTO TFT device treated at the 120 W condition exhibited excellent electrical characteristics in terms of a low threshold voltage of 0.14 V, high field-effect mobility of 29.8 cm2/Vs, high ION/IOFF current ratio of , and small subthreshold swing of 202 mV/decade.
Autors: Tung-Ming Pan;Bo-Jung Peng;Hung-Chun Wang;Jim-Long Her;Bih-Show Lou;
Appeared in: IEEE Electron Device Letters
Publication date: Mar 2017, volume: 38, issue:3, pages: 341 - 344
Publisher: IEEE
 
» Impact of X-Ray Tomography on the Reliability of Integrated Circuits
Abstract:
X-ray tomography provides 3-D information of an integrated circuit (IC) and has been utilized for counterfeit detection. Although it is a nondestructive process, electrical functionalities of IC under long time radiation has yet to be fully investigated. This paper analyzes the impact of X-ray tomography on the reliability of ICs with different fabrication technologies. We perform a 3-D imaging on Intel flash memories, Macronix flash memories, Xilinx Spartan 3, and Spartan 6 FPGAs and test the electrical functionalities after each round of tomography. We examine the impact of tomography on erase time, read margin, and program operation in flash memories. The change of ring oscillators frequency mapped in FPGAs is also investigated. A major finding is that tomography increases the erase time of flash memory of older technology nodes, eventually resulting in failure. In contrast, the flash and Xilinx FPGAs of newer technologies seem much less sensitive to tomography, as only minor degradations are observed. Degradation of IC performance is explained by considering total ionization dose effect due to tomography. Counterfeit detection requires approximately 2 h of tomography and no IC failed permanently during this time period.
Autors: Mahbub Alam;Haoting Shen;Navid Asadizanjani;Mark Tehranipoor;Domenic Forte;
Appeared in: IEEE Transactions on Device and Materials Reliability
Publication date: Mar 2017, volume: 17, issue:1, pages: 59 - 68
Publisher: IEEE
 
» Impact on Interarea Modes of Fast HVDC Primary Frequency Control
Abstract:
Primary frequency control is often added to the control system of a high-voltage DC (HVDC) transmission that interconnects two nonsynchronous ac grids. As the active-power actuation lag is typically in the range of hundreds of milliseconds, the HVDC primary frequency control can be made fast enough to permit inertia sharing among the interconnected ac grids. This reduces the maximum frequency fall after a loss-of-generation contingency (the nadir). A fast HVDC primary frequency control may affect the interarea modes of the interconnected grids. To this end, it is shown that, at least for the cases studied, the modal damping never decreases through the introduction of the mentioned control.
Autors: Lennart Harnefors;Nicklas Johansson;Lidong Zhang;
Appeared in: IEEE Transactions on Power Systems
Publication date: Mar 2017, volume: 32, issue:2, pages: 1350 - 1358
Publisher: IEEE
 
» Impacts of Remote Control Switch Malfunction on Distribution System Reliability
Abstract:
Remote control switches (RCSs) are often assumed to be fully reliable in reliability and cost/worth analyses. This assumption, however, overestimates their merits, thereby misguiding network owners about their optimal implementation. This letter extends the current reliability evaluation procedure to incorporate probability of RCS malfunctions. Then, the extended procedure is applied to a network equipped with a few RCSs. The numerical studies reveal that RCS malfunctions degrade their worth, which may even affect their optimal number and locations.
Autors: Amir Safdarian;Mohammad Farajollahi;Mahmud Fotuhi-Firuzabad;
Appeared in: IEEE Transactions on Power Systems
Publication date: Mar 2017, volume: 32, issue:2, pages: 1572 - 1573
Publisher: IEEE
 
» Implantable Technologies in the Military Sector [Concluding Remarks]
Abstract:
Autors: Philip Hall;
Appeared in: IEEE Technology and Society Magazine
Publication date: Mar 2017, volume: 36, issue:1, pages: 69 - 70
Publisher: IEEE
 
» Implanting Military RFID: Rights and Wrongs
Abstract:
There are potential benefits and potential risks that flow from the implantation of radio frequency identification (RFID) devices into humans. The potential benefits with respect to military personnel may be considered great enough to outweigh any potential risks. In particular, the ability to identify military personnel without the need for "dog tags," worn around the neck, could be beneficial.
Autors: Rob Nicholls;
Appeared in: IEEE Technology and Society Magazine
Publication date: Mar 2017, volume: 36, issue:1, pages: 48 - 51
Publisher: IEEE
 
» Implicit Common-Mode Resonance in LC Oscillators
Abstract:
The performance of a differential LC oscillator can be enhanced by resonating the common mode of the circuit at twice the oscillation frequency. When this technique is correctly employed, -degradation due to the triode operation of the differential pair is eliminated and flicker noise is nulled. Until recently, one or more tail inductors have been used to achieve this common-mode resonance. In this paper, we demonstrate that additional inductors are not strictly necessary by showing that common-mode resonance can be obtained using a single tank. We present an NMOS architecture that uses a single differential inductor and a CMOS design that uses a single transformer. Prototypes are presented that achieve figure-of-merits of 192 and 195 dBc/Hz, respectively.
Autors: David Murphy;Hooman Darabi;Hao Wu;
Appeared in: IEEE Journal of Solid-State Circuits
Publication date: Mar 2017, volume: 52, issue:3, pages: 812 - 821
Publisher: IEEE
 
» Importance of Matching Physical Friction, Hardness, and Texture in Creating Realistic Haptic Virtual Surfaces
Abstract:
Interacting with physical objects through a tool elicits tactile and kinesthetic sensations that comprise your haptic impression of the object. These cues, however, are largely missing from interactions with virtual objects, yielding an unrealistic user experience. This article evaluates the realism of virtual surfaces rendered using haptic models constructed from data recorded during interactions with real surfaces. The models include three components: surface friction, tapping transients, and texture vibrations. We render the virtual surfaces on a SensAble Phantom Omni haptic interface augmented with a Tactile Labs Haptuator for vibration output. We conducted a human-subject study to assess the realism of these virtual surfaces and the importance of the three model components. Following a perceptual discrepancy paradigm, subjects compared each of 15 real surfaces to a full rendering of the same surface plus versions missing each model component. The realism improvement achieved by including friction, tapping, or texture in the rendering was found to directly relate to the intensity of the surface's property in that domain (slipperiness, hardness, or roughness). A subsequent analysis of forces and vibrations measured during interactions with virtual surfaces indicated that the Omni's inherent mechanical properties corrupted the user's haptic experience, decreasing realism of the virtual surface.
Autors: Heather Culbertson;Katherine J. Kuchenbecker;
Appeared in: IEEE Transactions on Haptics
Publication date: Mar 2017, volume: 10, issue:1, pages: 63 - 74
Publisher: IEEE
 
» Improved Current Drivability for Sub-20-nm N-FinFETs by Ge Pre-Amorphization in Contact With Reverse Retrograde Profile
Abstract:
Prior to contact silicide formation, multiple Ge pre-amorphization implantation (PAI) with reverse retrograde Ge profile was investigated for sub-20-nm FinFETs. Compared with conventional single PAI, N-FinFETs from the new PAI scheme exhibit enhanced drive current by 12%, which can be attributed to decreased total series resistance () by 15% and enhanced peak electron mobility by 8%. The former arises from reduced Schottky barrier height and better crystallinity of C49/C54 TiSi2, while the latter is resulted from higher tensile strain in the channel induced by TiSi2 with more Ge incorporation. Furthermore, ring oscillator for the new PAI scheme shows better circuit performance as compared with conventional scheme in terms of 6% increase in output frequency. The newly developed PAI process is fully compatible with the incumbent ULSI technology and can be extended to sub-10-nm FinFETs.
Autors: Chuan-Pu Chou;Chin-Yu Chen;Kuen-Yi Chen;Shih-Chieh Teng;Jia-Hong Huang;Yung-Hsien Wu;
Appeared in: IEEE Electron Device Letters
Publication date: Mar 2017, volume: 38, issue:3, pages: 299 - 302
Publisher: IEEE
 
» Improved Damper Cage Design for Salient-Pole Synchronous Generators
Abstract:
The benefits of implementing a damper winding in salient-pole synchronous generators are widely known and well consolidated. It is also well known that such a winding incurs extra losses in the machine due to a number of reasons. In order to improve the overall efficiency and performance of classical salient-pole, wound field synchronous generators that employ the traditional damper cage, an improved amortisseur winding topology that reduces the inherent loss is proposed and investigated in this paper. This is essential in order to meet modern power quality requirements and to improve the overall performance of such “classical” machines. The new topology addresses the requirements for lower loss components without compromising the acceptable values of the output voltage total harmonic distortion and achieves this by having a modulated damper bar pitch. As vessel for studying the proposed concept, a 4-MVA salient-pole synchronous generator is considered. A finite element model of this machine is first built and then validated against experimental results. The validated model is then used to investigate the proposed concept with an optimal solution being achieved via the implementation of a genetic algorithm optimization tool. Finally, the performance of the optimized machine is compared to the original design both at a steady state and transient operating conditions.
Autors: Stefano Nuzzo;Michele Degano;Michael Galea;Chris Gerada;David Gerada;Neil Brown;
Appeared in: IEEE Transactions on Industrial Electronics
Publication date: Mar 2017, volume: 64, issue:3, pages: 1958 - 1970
Publisher: IEEE
 
» Improved Electrical Performance of Multilayer MoS2 Transistor With NH3-Annealed ALD HfTiO Gate Dielectric
Abstract:
The carrier mobility of MoS2 transistors can be greatly improved by the screening effect of high-k gate dielectric. Therefore, in this paper, atomic layer deposited HfTiO annealed in different ambients (N2, O2, and NH3) is used to replace SiO2 as gate dielectric for fabricating back-gated multilayer MoS2 transistors. As a result, excellent electrical properties are achieved for the sample annealed in NH3 at 400 °C for 10 min: the field-effect mobility of 31.1 cm/(V s) and the subthreshold swing of 100 mV/decade, which are six times higher and three times smaller compared with that of the control sample, respectively. The enhanced electrical performance should be associated with the passivation effects of the NH3 annealing, which reduces defective states in the HfTiO dielectric and at/near the HfTiO/MoS2 interface. The capacitance equivalent thickness of the gate dielectric (HfTiO) is only 6.79 nm, which is quite small for back-gated MoS2 transistor and is conducive to the scaling down of the device.
Autors: Ming Wen;Jingping Xu;Lu Liu;Pui-To Lai;Wing-Man Tang;
Appeared in: IEEE Transactions on Electron Devices
Publication date: Mar 2017, volume: 64, issue:3, pages: 1020 - 1025
Publisher: IEEE
 
» Improved Multiple Faults-Aware Placement Strategy: Reducing the Overheads and Error Rates in Digital Circuits
Abstract:
State-of-the-art commercial placement tools have as goals to optimize area, timing, and power. Over the years, several reliability oriented placement strategies have been proposed with distinct goals, such as to improve the error rate. However, we found that there are still improvements that can be made for this type of approach, to improve not only the error rates but also the performance of the placer itself. Thus, this paper proposes several improvements toward an efficient multiple faults-aware placement strategy. First, an analytical method to profile pair of gates is proposed. Second, we add another level of optimization to reduce the amount of wirelength observed after the placement is completed without jeopardizing the main objective (reliability). Third, we propose a way to manipulate white spaces between gates smartly, to separate the gates that are profiled as the most likely to reduce the error rate when paired adjacently in the circuit. Results show that a wirelength reduction of up to 61% is achieved. Also, additional reduction of the error rate of up to 23% can be achieved with only an overhead on placement execution time.
Autors: Mohamad Imran Bandan;Samuel Pagliarini;Jimson Mathew;Dhiraj Pradhan;
Appeared in: IEEE Transactions on Reliability
Publication date: Mar 2017, volume: 66, issue:1, pages: 233 - 244
Publisher: IEEE
 
» Improved Performance and Heat Dissipation of Flip-Chip White High-Voltage Light Emitting Diodes
Abstract:
Three types of white light emitting diodes (LEDs) were constructed with micro-cells. The first one is the convectional LED series connected with four cells using the wire-bonding process. The other two devices are lateral-type and flip-chip high-voltage LEDs (HV-LEDs) using the interconnection technique. The convectional LED, lateral-type HV-LED, and flip-chip HV-LED are denoted as C-LED, L-HV-LED, and FC-HV-LED, respectively. Moreover, the white LEDs were formed by combining the blue LED chips and the phosphor-dispensing method. The thermal resistances (at 20 mA) of C-LED, L-HV-LED, and FC-HV-LED were 14.5, 59.2, and 12.2 K/W, respectively. In addition, the surface temperatures (at 20 mA) of these three devices were 30.74–31.82, 65.93–68.95, and 27.01–27.96 °C, respectively. Obviously, the heat dissipation of L-HV-LED was much worse than that of C-LED. However, via the fabrication of the flip-chip structure, the heat dissipation of HV-LED can be enhanced significantly. At an injection current of 100 mA, the luminous efficiencies of C-LED, L-HV-LED, and FC-HV-LED were 80.8, 81.0, and 91.8 lm/W, respectively. Furthermore, at the same forward voltage, a higher current can be driven in the FC-HV-LED, leading to an apparent improvement in the luminous efficiency. According to our calculation, the emission size of HV-LED was only 84% compared with that of C-LED. On the other hand, the fabrication of HV-LED can be performed without the wire-bonding process. This indicates that the FC-HV-LED possesses not only lower production costs but also higher optoelectronic performance than that of the C-LED.
Autors: Ping-Chen Wu;Sin-Liang Ou;Ray-Hua Horng;Dong-Sing Wuu;
Appeared in: IEEE Transactions on Device and Materials Reliability
Publication date: Mar 2017, volume: 17, issue:1, pages: 197 - 203
Publisher: IEEE
 
» Improved Single-Phase Split-Source Inverter With Hybrid Quasi-Sinusoidal and Constant PWM
Abstract:
A single-stage topology of a three-phase boost inverter known as split-source inverter (SSI) has recently been introduced in the literature. This topology suffers from high frequency current commutations across two diodes and complicated analysis since the inductor is charged with variable duty cycle. This paper presents a single-phase version of SSI with improvements in inverter topology as well as the pulse width modulation (PWM) technique. An inductor is connected to two MOSFETs operating at fundamental frequency to boost the voltage from input source to dc-link voltage. In the proposed hybrid quasi-sinusoidal and constant PWM, one of the full-bridge legs undergoes constant duty cycle switching while the other one undergoes sinusoidally varying duty cycle switching, with the former is accountable for charging and discharging of inductor while the latter is accountable for producing ac output. Therefore, the proposed topology with hybrid quasi-sinusoidal and constant PWM exhibits the merit of simplicity since the control of dc-link voltage and ac output is detached within the single-stage topology. It is not liable to the undesired high frequency current commutation. In addition, a wide range of ac output voltage is achievable in either buck or boost operation. Theoretical analysis is presented and verified through simulation and experimental results.
Autors: Sze Sing Lee;Yeh En Heng;
Appeared in: IEEE Transactions on Industrial Electronics
Publication date: Mar 2017, volume: 64, issue:3, pages: 2024 - 2031
Publisher: IEEE
 
» Improvement in the Negative Bias Illumination Stress Stability for Silicon-Ion Implanted Amorphous InGaZnO Thin-Film Transistors
Abstract:
Using ion implantation, we doped amorphous InGaZnO (a-IGZO) with Si and investigated how this doping influenced device performance. The Si doping increased the electrical conductivity of the a-IGZO films, showing that the Si doping had produced the electron carriers. The optimum oxygen partial pressure during a-IGZO deposition moved toward higher in the Si-implanted a-IGZO thin-film transistors (TFTs) than in the undoped TFTs. In the doped TFTs, the gate bias stability against negative bias illumination stress (NBIS) improved, while the mobility remained almost the same as that without Si doping. This improvement in the NBIS stability suggests that the subgap states related to oxygen-vacancies could be reduced in the Si-implanted a-IGZO film.
Autors: Tetsuya Goto;Fuminobu Imaizumi;Shigetoshi Sugawa;
Appeared in: IEEE Electron Device Letters
Publication date: Mar 2017, volume: 38, issue:3, pages: 345 - 348
Publisher: IEEE
 
» Improving $B_{1}$ Efficiency and Signal-to-Noise-Ratio of a Surface Coil by a High-Impedance-Surface RF Shield for 7-T Magnetic Resonance Imaging
Abstract:
In this paper, we present a fundamental investigation to improve the efficiency and the signal-to-noise ratio (SNR) of a radio frequency (RF) surface coil for ultrahigh-field magnetic resonance imaging (MRI) by utilizing a high-impedance surface (HIS) as the RF shield. An analytical investigation indicates that a circular loop backed by a perfect magnetic conductor (PMC), which is the ideal case of an HIS, suggests an improved magnetic field compared with the case of a perfect electric conductor (PEC) and the case without any shield. This improvement is verified by a full-wave simulation, where the surface coil is modeled by an ideal impressed current model with azimuthal component ( A/m). The electromagnetic field is effectively shielded out behind the PEC and PMC shields compared with the case without any shield. Furthermore, the surface coil with uniform current distribution and the PMC shield is realized by a series resonant loop structure and a 2-D HIS structure, respectively. Since the normal component of the magnetic field is supported at the surface of an HIS, whereas suppressed by a conventional PEC, the field in the vicinity of the HIS shield is enhanced compared with the case with a PEC shield. Hence, an improvement on SNR and efficiency is achieved by utilizing an HIS shield, especially in the regions adjacent to the surface coil. It has been found that the improvement of efficiency is more prominent than the improvement of SNR due to different normalizations. The difference of peak SAR between considered- shields, which is used for efficiency normalization, is considerably larger than the difference of the power loss within the phantom, which is used for the SNR normalization. The proposed approach is validated by full-wave finite-element method simulations and near-field measurements, which reveal good agreement with each other.
Autors: Zhichao Chen;Klaus Solbach;Daniel Erni;Andreas Rennings;
Appeared in: IEEE Transactions on Microwave Theory and Techniques
Publication date: Mar 2017, volume: 65, issue:3, pages: 988 - 997
Publisher: IEEE
 
» Improving Automated Bug Triaging with Specialized Topic Model
Abstract:
Bug triaging refers to the process of assigning a bug to the most appropriate developer to fix. It becomes more and more difficult and complicated as the size of software and the number of developers increase. In this paper, we propose a new framework for bug triaging, which maps the words in the bug reports (i.e., the term space) to their corresponding topics (i.e., the topic space). We propose a specialized topic modeling algorithm named multi-feature topic model (MTM) which extends Latent Dirichlet Allocation (LDA) for bug triaging. MTM considers product and component information of bug reports to map the term space to the topic space. Finally, we propose an incremental learning method named TopicMiner which considers the topic distribution of a new bug report to assign an appropriate fixer based on the affinity of the fixer to the topics. We pair TopicMiner with MTM (TopicMiner). We have evaluated our solution on 5 large bug report datasets including GCC, OpenOffice, Mozilla, Netbeans, and Eclipse containing a total of 227,278 bug reports. We show that TopicMiner can achieve top-1 and top-5 prediction accuracies of 0.4831-0.6868, and 0.7686-0.9084, respectively. We also compare TopicMiner with Bugzie, LDA-KL, SVM-LDA, LDA-Activity, and Yang et al.'s approach. The results show that TopicMiner on average improves top-1 and top-5 prediction accuracies of Bugzie by 128.48 and 53.22 percent, LDA-KL by 262.91 and 105.97 percent, SVM-LDA by 205.89 and 110.48 percent, LDA-Activity by 377.60 and 176.32 percent, and Yang et al.'s approach by 59.88 and 13.70 percent, respectively.
Autors: Xin Xia;David Lo;Ying Ding;Jafar M. Al-Kofahi;Tien N. Nguyen;Xinyu Wang;
Appeared in: IEEE Transactions on Software Engineering
Publication date: Mar 2017, volume: 43, issue:3, pages: 272 - 297
Publisher: IEEE
 
» Improving DRAM Performance in 3-D ICs via Temperature Aware Refresh
Abstract:
The 3-D integration allows IC designs to stack DRAM directly on the top of execution units, which greatly reduces DRAM access latency and improves memory bandwidth. Unfortunately, the heat generated by the processor unit cannot be effectively dissipated. As a result, DRAM operating temperature is undesirably increased. Due to the fact that 3-D-stacked DRAM operates under a severe thermal condition manifested as escalated hot spots and large temperature gradients, conventional refresh schemes based on the peak temperature lead to high refresh rates, which introduce large performance degradation in 3-D-stacked DRAM. To address this problem, we propose the temperature aware refresh technique for 3-D-stacked DRAM. The goal is to mitigate this performance degradation by adjusting the refresh rates of DRAM banks based on their actual thermal conditions at runtime. As a result, only banks that work in the peak temperature will refresh frequently, while the rest of the banks can be refreshed at a reduced rate. This enables more read and write accesses, which improves the overall memory performance.
Autors: Menglong Guan;Lei Wang;
Appeared in: IEEE Transactions on Very Large Scale Integration Systems
Publication date: Mar 2017, volume: 25, issue:3, pages: 833 - 843
Publisher: IEEE
 
» Improving Our Bodies, Our Meals, and Our Gadgets
Abstract:
This installment of Notes from the Community covers new pervasive technologies using metamaterials, flexible and stretchable electronics, sensors, robotics, 3D printing, tofu, and more.
Autors: Mary Baker;Justin Manweiler;
Appeared in: IEEE Pervasive Computing
Publication date: Mar 2017, volume: 16, issue:1, pages: 85 - 88
Publisher: IEEE
 
» Improving Performance of Heterogeneous MapReduce Clusters with Adaptive Task Tuning
Abstract:
Datacenter-scale clusters are evolving toward heterogeneous hardware architectures due to continuous server replacement. Meanwhile, datacenters are commonly shared by many users for quite different uses. It often exhibits significant performance heterogeneity due to multi-tenant interferences. The deployment of MapReduce on such heterogeneous clusters presents significant challenges in achieving good application performance compared to in-house dedicated clusters. As most MapReduce implementations are originally designed for homogeneous environments, heterogeneity can cause significant performance deterioration in job execution despite existing optimizations on task scheduling and load balancing. In this paper, we observe that the homogeneous configuration of tasks on heterogeneous nodes can be an important source of load imbalance and thus cause poor performance. Tasks should be customized with different configurations to match the capabilities of heterogeneous nodes. To this end, we propose a self-adaptive task tuning approach, Ant, that automatically searches the optimal configurations for individual tasks running on different nodes. In a heterogeneous cluster, Ant first divides nodes into a number of homogeneous subclusters based on their hardware configurations. It then treats each subcluster as a homogeneous cluster and independently applies the self-tuning algorithm to them. Ant finally configures tasks with randomly selected configurations and gradually improves tasks configurations by reproducing the configurations from best performing tasks and discarding poor performing configurations. To accelerate task tuning and avoid trapping in local optimum, Ant uses genetic algorithm during adaptive task configuration. Experimental results on a heterogeneous physical cluster with varying hardware capabilities show that Ant improves the average job completion time by 31, 20, and 14 percent compared to stock Hadoop (Stock), customized Hadoop with in- ustry recommendations (Heuristic), and a profiling-based configuration approach (Starfish), respectively. Furthermore, we extend Ant to virtual MapReduce clusters in a multi-tenant private cloud. Specifically, Ant characterizes a virtual node based on two measured performance statistics: I/O rate and CPU steal time. It uses k-means clustering algorithm to classify virtual nodes into configuration groups based on the measured dynamic interference. Experimental results on virtual clusters with varying interferences show that Ant improves the average job completion time by 20, 15, and 11 percent compared to Stock, Heuristic and Starfish, respectively.
Autors: Dazhao Cheng;Jia Rao;Yanfei Guo;Changjun Jiang;Xiaobo Zhou;
Appeared in: IEEE Transactions on Parallel and Distributed Systems
Publication date: Mar 2017, volume: 28, issue:3, pages: 774 - 786
Publisher: IEEE
 
» Improving Quality of Experience in Future Wireless Access Networks through Fog Computing
Abstract:
A novel model of Internet access networks is proposed, based on fog computing. The model hosts applications close to users by relying on virtual machines to dynamically move cloud or Web content to nodes located at the edge of access networks. Then it can perform proactive caching and enforce traffic policies based on the interaction between access infrastructure and external applications. By analyzing experimental data collected from public Wi-Fi hotspots, the authors quantify the benefits of this approach for bandwidth usage optimization, latency reduction, and quality of experience enhancement. Experimental results show that a significant portion (from 28 to 50 percent) of download data could be managed by the fog node. On the basis of these findings, useful insights for future-generation access networks are provided.
Autors: Nicola Iotti;Marco Picone;Simone Cirani;Gianluigi Ferrari;
Appeared in: IEEE Internet Computing
Publication date: Mar 2017, volume: 21, issue:2, pages: 26 - 33
Publisher: IEEE
 
» Improving Safety on Highways by Customizing Vehicular Ad Hoc Networks
Abstract:
This paper studies the need for individualizing vehicular communications in order to improve safety for a highway scenario. Adapting a vehicular ad hoc network to both its individual driver’s characteristic and traffic conditions enables it to transmit in a smart manner to other vehicles. This radical improvement is now possible due to the progress that is being made in vehicular ad hoc networks (VANET). In this paper, we first derive the packet success probability for a chain of vehicles by taking multi-user interference, path loss, and fading into account. Then, by considering the delay constraints and types of potential collisions, we approximate the optimal channel access probabilities. Lastly, we propose an algorithm for customizing channel access probabilities in VANET. Our Monte Carlo simulation results show that this approach achieves more than 25% reduction in traffic collision probability compared with the case with equal channel access probabilities in its optimal range. Therefore, it has a huge advantage over other non-optimal systems.
Autors: Ali Rakhshan;Hossein Pishro-Nik;
Appeared in: IEEE Transactions on Wireless Communications
Publication date: Mar 2017, volume: 16, issue:3, pages: 2017 - 2026
Publisher: IEEE
 
» Improving the Accuracy of Human Body Orientation Estimation With Wearable IMU Sensors
Abstract:
Accurately estimating the orientation of different human body segments using low cost inertial sensors is a key component in various activity-related and healthcare-related applications. Typically, the signals from a gyroscope and an accelerometer are fused inside a Kalman filter to determine the orientation. However, the accelerometer measurements are influenced by the linear accelerations of the body segments in addition to the gravitational acceleration that corrupts the orientation estimates. The conventional method to deal with linear acceleration is to model it as a first-order low-pass process and estimate it inside the Kalman filter. In this conventional method, important information from those sensor axes that do not experience linear accelerations is lost. In this paper, we modify the conventional approach to deal with the problem of linear acceleration more efficiently. The proposed approach estimates the direction of linear acceleration and assigns lower weights inside the Kalman filter to only those sensor axes that are experiencing acceleration, thus conserving important information from other axes measurements. The proposed method is compared with the conventional method using simulations and experimentation on a test subject performing daily routine tasks. The results indicate a significant performance improvement in orientation estimation.
Autors: Hamad Ahmed;Muhammad Tahir;
Appeared in: IEEE Transactions on Instrumentation and Measurement
Publication date: Mar 2017, volume: 66, issue:3, pages: 535 - 542
Publisher: IEEE
 
» Improving Timeliness and Visibility in Publishing Software Engineering Research
Abstract:
Autors: Matthew B. Dwyer;
Appeared in: IEEE Transactions on Software Engineering
Publication date: Mar 2017, volume: 43, issue:3, pages: 205 - 206
Publisher: IEEE
 
» In Situ Oxide, GaN Interlayer-Based Vertical Trench MOSFET (OG-FET) on Bulk GaN substrates
Abstract:
In this letter, we report on high breakdown voltage in situ oxide, GaN interlayer-based vertical trench MOSFETs (OG-FETs) on bulk GaN substrates. Following our previous work on OG-FETs on GaN on sapphire, utilizing a low damage gate-trench etch and using bulk GaN substrates, a breakdown voltage of 990 V with an on-resistance 2.6 cm2, was achieved. Without edge termination, a high breakdown field of 1.6 MV/cm was achieved in these devices.
Autors: Chirag Gupta;Cory Lund;Silvia H. Chan;Anchal Agarwal;Junquian Liu;Yuuki Enatsu;Stacia Keller;Umesh K. Mishra;
Appeared in: IEEE Electron Device Letters
Publication date: Mar 2017, volume: 38, issue:3, pages: 353 - 355
Publisher: IEEE
 
» In the First Few Blinks of an Eye: The Basics of Engaging Presentation [Speakers' Corner]
Abstract:
Outlines some of the issues we face when preparing for and then delivering a presentation, and we provide hints at the barriers we would like to dismantle on the road to engaging, accessible, and compelling presentations.
Autors: John W. Bandler;Erin M. Kiley;
Appeared in: IEEE Microwave Magazine
Publication date: Mar 2017, volume: 18, issue:2, pages: 112 - 120
Publisher: IEEE
 
» Incipient Bearing Damage Monitoring of 940-h Variable Speed Drive System Operation
Abstract:
Inverter-induced high-frequency bearing currents are a recognized cause of bearing failure in frequency converter-fed electric machines. Mechanical bearing faults are generally identified by vibration measurements. In this work, we submit bearings to electric discharge machining bearing currents, measure the electrical stress placed on the bearings, the resulting vibration signal and operating temperature, and apply time- and frequency-domain signal processing techniques for feature extraction. Experiments are run for 940 h of operation, so as to study the incipient bearing failure behavior. After the end of the test run, the bearing surfaces are inspected using scanning electron microscopy.
Autors: Aleksei Romanenko;Annette Muetze;Jero Ahola;
Appeared in: IEEE Transactions on Energy Conversion
Publication date: Mar 2017, volume: 32, issue:1, pages: 99 - 110
Publisher: IEEE
 
» Incorporating Spectral Similarity Into Markov Chain Geostatistical Cosimulation for Reducing Smoothing Effect in Land Cover Postclassification
Abstract:
Spatial statistics provides useful methods for incorporating spatial dependence into land cover classification. However, the geometric features of land cover classes are difficult to be captured by geostatistical models due to smoothing effect. The objective of this study is to incorporate spectral similarity into the Markov chain random field (MCRF) cosimulation (coMCRF) model, that is, to propose a spectral similarity-enhanced MCRF cosimulation (SS-coMCRF) model, for land cover postclassification so that postclassification will cause less geometric loss. Two mutually complementary spectral similarity measures, Jaccard index and the spectral correlation measure, were employed as a constraining factor in SS-coMCRF. One medium spatial resolution scene with a complex landscape and one very high spatial resolution scene with an urban landscape were selected for case studies. Neural network classifier and support vector machine classifier were used to conduct land cover preclassifications. Both coMCRF and SS-coMCRF were used to postprocess preclassified images based on expert-interpreted sample datasets from multiple data sources. Compared with preclassified results that depend on only spectral information of pixels, postclassifications by both models achieved similar significant improvements in overall accuracy. However, compared with coMCRF, the SS-coMCRF model apparently improved postclassified land cover patterns by effectively capturing some geometric features (e.g., boundaries and linear stripes) and more details of land cover classes. In general, incorporating spectral similarity into land cover postclassification through SS-coMCRF may contribute significantly to the “shape” or geometric accuracy of classified land cover classes.
Autors: Weixing Zhang;Weidong Li;Chuanrong Zhang;Xiaojiang Li;
Appeared in: IEEE Journal of Selected Topics in Applied Earth Observations and Remote Sensing
Publication date: Mar 2017, volume: 10, issue:3, pages: 1082 - 1095
Publisher: IEEE
 
» Indoor Use of Gray and White Spaces: Another Look at Wireless Indoor Communication
Abstract:
Television (TV) white space (WS) constitutes a key technology to support the increasing worldwide growth of spectrum demand with several regulation standards that are already available for long- and medium-range communications. At the same time, estimations based on WS spectrum databases (SDBs) indicate that the availability of TVWS is often very limited in dense urban areas where spectrum resources are more needed. Therefore, the benefits provided by the utilization of TVWS have yet to be fully assessed. In this article, we rethink the utilization of TVWS in indoor communication environments through novel three-dimensional (3-D) spectrum-sharing mechanisms. Based on measurements that demonstrate the differences in terms of spectrum opportunities at different floors of the same building, we propose an underlay spectrum-sharing architecture to enable a per-building finegrained reuse of TV frequencies while protecting the operations of TV receivers in a neighborhood. We evaluate the effectiveness of the proposed spectrum-sharing architecture over several urban environments in Italy by taking into account many real characteristics of the scenarios. Our results demonstrate that through our architecture, more spectrum resources than what are reported in the SDB can be available for indoor scenarios, even in highly congested urban areas, paving the way to novel TVWS applications.
Autors: Luca Bedogni;Fabio Malabocchia;Marco Di Felice;Luciano Bononi;
Appeared in: IEEE Vehicular Technology Magazine
Publication date: Mar 2017, volume: 12, issue:1, pages: 63 - 71
Publisher: IEEE
 
» Industrial Cyberphysical Systems: A Backbone of the Fourth Industrial Revolution
Abstract:
Cyberphysical systems (CPSs) are perceived as the pivotal enabler for a new era of real-time Internetbased communication and collaboration among value-chain participants, e.g., devices, systems, organizations, and humans. The CPS utilization in industrial settings is expected to revolutionize the way enterprises conduct their business from a holistic viewpoint, i.e., from shop-floor to business interactions, from suppliers to customers, and from design to support across the whole product and service lifecycle. Industrial CPS (ICPSs) blur the fabric of cyber (including business) and physical worlds and kickstart an era of systemwide collaboration and information-driven interactions among all stakeholders of the value chain. Therefore, ICPSs are expected to empower the transformation of industry and business at large to a digital, adaptive, networked, and knowledge-based industry with significant long-term impact on the economy, society, environment, and citizens.
Autors: Armando W. Colombo;Stamatis Karnouskos;Okyay Kaynak;Yang Shi;Shen Yin;
Appeared in: IEEE Industrial Electronics Magazine
Publication date: Mar 2017, volume: 11, issue:1, pages: 6 - 16
Publisher: IEEE
 
» Inference for Constant-Stress Accelerated Life Tests With Dependent Competing Risks From Bivariate Birnbaum–Saunders Distribution Based on Adaptive Progressively Hybrid Censoring
Abstract:
In life testing, the competing risks model is usually discussed under the assumption of independence. In this paper, we consider a dependent competing risks model using bivariate Birnbaum–Saunders distribution in constant-stress accelerated life testing. To observe expected failure times and terminate the life tests around a predetermined time, the adaptive progressively hybrid censoring scheme is adopted. Based on the accelerated competing risks model with the adaptive progressively hybrid censoring scheme, we obtain the maximum-likelihood estimators, approximate confidence intervals, and bootstrap confidence intervals of unknown parameters. To test the independence between the bivariate competing risks and find the relationship of shape and scale parameters, we discuss the likelihood ratio tests for hypotheses of interest. In addition, we compute the maximum-likelihood predictors of unobserved competing risks times in the constant-stress accelerated life tests. Finally, a simulation study and an illustrative example are provided to support the proposed model and methods, and to examine the performance of estimators and testing.
Autors: Chunfang Zhang;Yimin Shi;Xuchao Bai;Qianrao Fu;
Appeared in: IEEE Transactions on Reliability
Publication date: Mar 2017, volume: 66, issue:1, pages: 111 - 122
Publisher: IEEE
 
» Influence Maximization in Trajectory Databases
Abstract:
In this paper, we study a novel problem of influence maximization in trajectory databases that is very useful in precise location-aware advertising. It finds best trajectories to be attached with a given advertisement and maximizes the expected influence among a large group of audience. We show that the problem is NP-hard and propose both exact and approximate solutions to find the best set of trajectories. In the exact solution, we devise an expansion-based framework that enumerates trajectory combinations in a best-first manner and propose three types of upper bound estimation techniques to facilitate early termination. In addition, we propose a novel trajectory index to reduce the influence calculation cost. To support large , we propose a greedy solution with an approximation ratio of (1 − 1/e), whose performance is further optimized by a new proposed cluster-based method. We also propose a threshold method that can support any approximation ratio . In addition, we extend our problem to support the scenario when there are a group of advertisements. In our experiments, we use real datasets to construct user profiles, motion patterns, and trajectory databases. The experimental results verified the efficiency of our proposed methods.
Autors: Long Guo;Dongxiang Zhang;Gao Cong;Wei Wu;Kian-Lee Tan;
Appeared in: IEEE Transactions on Knowledge and Data Engineering
Publication date: Mar 2017, volume: 29, issue:3, pages: 627 - 641
Publisher: IEEE
 
» Influence of Compositing Criterion and Data Availability on Pixel-Based Landsat TM/ETM+ Image Compositing Over Amazonian Forests
Abstract:
Persistent cloud cover is an important obstacle to studying the ground surface of tropical rain forest areas using high-resolution optical data, such as those obtained with Landsat satellites. The identification and masking of the cloud-affected parts of such images is a necessary preprocessing step, but it easily leads to impractical fragmentation of the informative image area. Pixel-based multitemporal image compositing solves the fragmentation problem, but depends on a predefined compositing period length and compositing criterion. Here, we evaluate the radiometric consistency of Landsat TM/ETM+ composite images over undisturbed Amazonian forests and test to what degree it varies with the number of available multitemporal observations per pixel and the compositing criterion. Five compositing criteria were tested: maximum NDVI, median red, median near-infrared, multidimensional medoid, and minimum aerosol optical thickness. Each was applied to datasets consisting of 3–30 observations per pixel. Compositing quality was assessed both visually and with quantitative measures using the overlap area of neighboring WRS-2 scenes. We found that the medoid approach generated the most radiometrically consistent composite images. Composite image quality increased monotonically with the number of observations, but with diminishing returns. Satisfactory results were generally obtained with 10–15 observations per pixel.
Autors: Jasper Van doninck;Hanna Tuomisto;
Appeared in: IEEE Journal of Selected Topics in Applied Earth Observations and Remote Sensing
Publication date: Mar 2017, volume: 10, issue:3, pages: 857 - 867
Publisher: IEEE
 
» Influence of Different Cutting Techniques on the Magnetic Characteristics of Electrical Steels Determined by a Permeameter
Abstract:
In this paper, the influence of three different cutting techniques, in particular mechanical cutting, solid-state laser cutting, and carbon dioxide laser cutting, on the quasi-static hysteresis curves of three different materials, commonly used with electric machines, is investigated. Furthermore, the additional effects of sample size and cutting direction are discussed. In contrast to the commonly used Epstein frame or ring sample tests, the examinations are carried out with a permeameter. A significantly different shape of the hysteresis curves of the small laser-cut in contrast to the mechanically cut samples is found. Furthermore, for some samples a point of intersection is observed above which the magnetic behavior of laser-cut samples is better than that of the mechanically cut samples.
Autors: Madeleine Bali;Annette Muetze;
Appeared in: IEEE Transactions on Industry Applications
Publication date: Mar 2017, volume: 53, issue:2, pages: 971 - 981
Publisher: IEEE
 
» Influence of Different Gate Biases and Gate Lengths on Parasitic Source Access Resistance in AlGaN/GaN Heterostructure FETs
Abstract:
The AlGaN/GaN heterostructure FETs with different gate lengths were fabricated. Under different gate biases or for the devices with different gate lengths, the measured parasitic source access resistance values were different. By the analysis of different scattering mechanisms and polarization charge distribution, it is found that the gate bias and gate length can change the polarization Coulomb field scattering, and then affect the parasitic source access resistance. At last, the systematic scattering theories were adopted and the influence of different gate biases and gate lengths on parasitic source access resistance was further confirmed in theory.
Autors: Peng Cui;Huan Liu;Wei Lin;Zhaojun Lin;Aijie Cheng;Ming Yang;Yan Liu;Chen Fu;Yuanjie Lv;Chongbiao Luan;
Appeared in: IEEE Transactions on Electron Devices
Publication date: Mar 2017, volume: 64, issue:3, pages: 1038 - 1044
Publisher: IEEE
 
» Influence of Geometry and Assembly Processes on the Building Factor of the Stator Core of the Synchronous Reluctance Motor
Abstract:
This paper deals with the results of measurements, calculations, and computer simulations, leading to the determination of the stator core's building factor (BF) of the fractional power synchronous reluctance motor (350 W). In the process of calculation, the authors indicated the part of the BF factor resulting from the punching process, the geometry of the stator core, and the fabrication process carried out during manufacture of the core. The obtained results indicate that for the analyzed core, the BF factor component resulting from the punching is greater than the sum of the components coming from clamping and pressing the core into the housing. The factor component dependent on geometry is less important. The data necessary for the finite-element method modeling were obtained from the modified SST system, whose idea has been described in detail.
Autors: Zbigniew Gmyrek;Marcin Lefik;
Appeared in: IEEE Transactions on Industrial Electronics
Publication date: Mar 2017, volume: 64, issue:3, pages: 2443 - 2450
Publisher: IEEE
 
» Influence of the Design of Square p+ Islands on the Characteristics of 4H-SiC JBS
Abstract:
A novel diagonal square array junction barrier Schottky (JBS) diode is created to enhance the forward current and reverse breakdown voltage by increasing the Schottky contact area and shortening the diagonal spacing between two adjacent p+ islands in the active area of a JBS diode. The shape of the p+ islands is square and the positional arrangement of the p+ islands is a diagonal array. Half of the upper and lower p+ islands with smaller areas are connected with the innermost p+ guard ring to create more Schottky contact area and laterally extend the electric field to the edge termination. Results show that the forward current density and reverse breakdown voltage for the diagonal square array JBS diode are 4.2% and 10.7% higher than those for the conventional square array JBS diode, respectively. As the spacing increases, the breakdown voltage for the diagonal square array JBS diode and the conventional square array JBS diode decrease by 3.5% and 7.3%, respectively, indicating that the diagonal square array JBS has more uniform depletion regions and electric field to retain the breakdown voltage.
Autors: Kung-Yen Lee;Yuan-Heng Liu;Sheng-Chung Wang;Le-Shan Chan;
Appeared in: IEEE Transactions on Electron Devices
Publication date: Mar 2017, volume: 64, issue:3, pages: 1394 - 1398
Publisher: IEEE
 
» Information Visualization
Abstract:
In addition to many fine department contributions, this issue contains several feature articles from the CG&A general queue on information visualization and visual analytics.
Autors: L. Miguel Encarnação;
Appeared in: IEEE Computer Graphics and Applications
Publication date: Mar 2017, volume: 37, issue:2, pages: 6 - 7
Publisher: IEEE
 
» Information Without Rolling Dice
Abstract:
The deterministic notions of capacity and entropy are studied in the context of communication and storage of information using square-integrable and bandlimited signals subject to perturbation. The -capacity that extends the Kolmogorov -capacity to packing sets of overlap at most is introduced and compared with the Shannon capacity. The functional form of the results indicates that in both Kolmogorov and Shannon’s settings, capacity and entropy grow linearly with the number of degrees of freedom, but only logarithmically with the signal to noise ratio. This basic insight transcends the details of the stochastic or deterministic description of the information-theoretic model. For , the analysis leads to a tight asymptotic expression of the Kolmogorov -entropy of bandlimited signals. A deterministic notion of error exponent is introduced. Applications of the theory are briefly discussed.
Autors: Taehyung J. Lim;Massimo Franceschetti;
Appeared in: IEEE Transactions on Information Theory
Publication date: Mar 2017, volume: 63, issue:3, pages: 1349 - 1363
Publisher: IEEE
 
» Information-Theoretic Lower Bounds on Bayes Risk in Decentralized Estimation
Abstract:
We derive lower bounds on the Bayes risk in decentralized estimation, where the estimator does not have direct access to the random samples generated conditionally on the random parameter of interest, but only to the data received from local processors that observe the samples. The received data are subject to communication constraints due to the quantization and the noisy communication channels from the processors to the estimator. We first derive general lower bounds on the Bayes risk using information-theoretic quantities, such as mutual information, information density, small ball probability, and differential entropy. We then apply these lower bounds to the decentralized case, using strong data processing inequalities to quantify the contraction of information due to communication constraints. We treat the cases of a single processor and of multiple processors, where the samples observed by different processors may be conditionally dependent given the parameter, for noninteractive and interactive communication protocols. Our results recover and improve recent lower bounds on the Bayes risk and the minimax risk for certain decentralized estimation problems, where previously only conditionally independent sample sets and noiseless channels have been considered. Moreover, our results provide a general way to quantify the degradation of estimation performance caused by distributing resources to multiple processors, which is only discussed for specific examples in existing works.
Autors: Aolin Xu;Maxim Raginsky;
Appeared in: IEEE Transactions on Information Theory
Publication date: Mar 2017, volume: 63, issue:3, pages: 1580 - 1600
Publisher: IEEE
 
» InGaAs QW-MOSFET Performance Improvement Using a PEALD-AlN Passivation Layer and an In-Situ NH3 Post Remote-Plasma Treatment
Abstract:
In this letter, we report on the impact of a PEALD-AlN interfacial passivation layer (IPL) and an in-situ NH3 post remote-plasma (PRP) treatment onto InGaAs quantum-well MOSFETs with Ti/HfO2/InGaAs gate stack. Transistors with gate lengths down to 80 nm have been fabricated and characterized. Due to the excellent interfacial quality of HfO2/AlN/InGaAs, the subthreshold swing and the peak effective channel mobility have been improved to 93 mV/decade and 4253 cm2/Vs, respectively. The drain current has also shown a 4.6-fold enhancement, to 164 mA/mm ( nA/ and V), compared with the HfO2 control device. The results also show that the HfO2/AlN device exhibits better immunity to short-channel effects (SCEs) than the HfO2 control device. Furthermore, during positive bias temperature instability stress, a smaller and a lower were observed for the sample with an AlN IPL and NH3 PRP treatment, indicating that it is more reliable than the sample without any IPL or plasma treatment.
Autors: Po-Chun Chang;Quang-Ho Luc;Yueh-Chin Lin;Yen-Ku Lin;Chia-Hsun Wu;Simon M. Sze;Edward Yi Chang;
Appeared in: IEEE Electron Device Letters
Publication date: Mar 2017, volume: 38, issue:3, pages: 310 - 313
Publisher: IEEE
 
» Initial Steps Toward a Cellular Vehicle-to-Everything Standard [Connected Vehicles]
Abstract:
The Third Generation Partnership Project (3GPP) has developed some functionalities to provide enhancements of cellular standards specifically for vehicular communications. These include both direct communication (between vehicles, vehicle-to-pedestrian, and vehicleto-infrastructure) and cellular communications with networks. The vehicle-to-vehicle (V2V) work item builds on earlier work on device-todevice (D2D) communications and introduces a new D2D interface (designated as PC5, which is also known as the sidelink at the physical layer), specifically addressing communications at vehicular speeds. To that end, four additional pilot symbols have been added to the demodulation reference signal to allow for better tracking of the channel despite high Doppler effects associated with relative speeds of up to 500 km/h and at high frequency (with 5.9 GHz ITS band being the main target).
Autors: Elisabeth Uhlemann;
Appeared in: IEEE Vehicular Technology Magazine
Publication date: Mar 2017, volume: 12, issue:1, pages: 14 - 19
Publisher: IEEE
 
» Innovating Transport with QUIC: Design Approaches and Research Challenges
Abstract:
In today's Internet, there are many challenges such as low-latency support for interactive communication, security and privacy of user data, as well as development and deployment of new transport mechanisms. Quick UDP Internet Connections (QUIC) is a new transport protocol that addresses these challenges, focusing on HTTP/2 transmission as a first use case. The first QUIC working group meeting took place at IETF-97 in November 2016, and it has begun the standardization process. This article introduces the key features of QUIC and discusses the potential challenges that require further consideration.
Autors: Yong Cui;Tianxiang Li;Cong Liu;Xingwei Wang;Mirja Kühlewind;
Appeared in: IEEE Internet Computing
Publication date: Mar 2017, volume: 21, issue:2, pages: 72 - 76
Publisher: IEEE
 
» Input Design-Based Compensation Control for Networked Nonlinear Systems With Random Delays and Packet Dropouts
Abstract:
This brief investigates the data-based networked control problem of a class of nonlinear systems, where random network-induced delays and packet dropouts in the feedback and forward channels are considered simultaneously and further treated as random round-trip time (RTT) delays. The main contributions of this brief are as follows: 1) To actively compensate for RTT delays, a novel compensation control scheme is proposed based on the control input design, and thus, only one control command needs to be transmitted to the actuator through the network; 2) an explicit sufficient condition is derived to ensure the stability of the resulting closed-loop system as well as a zero steady-state output error for a constant reference input; and 3) numerical simulation and comparison with existing methods are carried out to show the effectiveness of the proposed method.
Autors: Zhong-Hua Pang;Guo-Ping Liu;Donghua Zhou;Dehui Sun;
Appeared in: IEEE Transactions on Circuits and Systems II: Express Briefs
Publication date: Mar 2017, volume: 64, issue:3, pages: 299 - 303
Publisher: IEEE
 
» Input Voltage Sensorless Duty Compensation Control for a Three-Phase Boost PFC Converter
Abstract:
This paper proposes an input voltage sensorless control algorithm for three-phase active boost rectifiers. Using this approach, the input ac-phase voltages can be accurately estimated from the fluctuations of other measured state variables and preceding switching state information from converter dynamics. Furthermore, the proposed control strategy reduces the input current harmonics of an ac–dc three-phase boost power factor correction (PFC) converter by injecting an additional common-mode duty ratio term to the feedback controllers’ outputs. This additional duty compensation term cancels the unwanted input harmonics, caused by the floating potential between ac source neutral and dc link negative, without requiring any access to the neutral point. A 6-kW (continuous power)/10-kW (peak power) three-phase boost PFC prototype using SiC-based semiconductor switching devices is designed and developed to validate the proposed control algorithm. The experimental results show that an input power factor of 0.999 with a conversion efficiency of 98.3%, total harmonic distortion as low as 4%, and a tightly regulated dc-link voltage with 1% ripple can be achieved.
Autors: Ayan Mallik;Weisheng Ding;Chuan Shi;Alireza Khaligh;
Appeared in: IEEE Transactions on Industry Applications
Publication date: Mar 2017, volume: 53, issue:2, pages: 1527 - 1537
Publisher: IEEE
 
» Insights Into Tunnel FET-Based Charge Pumps and Rectifiers for Energy Harvesting Applications
Abstract:
In this paper, the electrical characteristics of tunnel field-effect transistor (TFET) devices are explored for energy harvesting front-end circuits with ultralow power consumption. Compared with conventional thermionic technologies, the improved electrical characteristics of TFET devices are expected to increase the power conversion efficiency of front-end charge pumps and rectifiers powered at sub- power levels. However, under reverse bias conditions the TFET device presents particular electrical characteristics due to its different carrier injection mechanism. In this paper, it is shown that reverse losses in TFET-based circuits can be attenuated by changing the gate-to-source voltage of reverse-biased TFETs. Therefore, in order to take full advantage of the TFETs in front-end energy harvesting circuits, different circuit approaches are required. In this paper, we propose and discuss different topologies for TFET-based charge pumps and rectifiers for energy harvesting applications.
Autors: David Cavalheiro;Francesc Moll;Stanimir Valtchev;
Appeared in: IEEE Transactions on Very Large Scale Integration Systems
Publication date: Mar 2017, volume: 25, issue:3, pages: 988 - 997
Publisher: IEEE
 
» Integration of Prism Sheet on Quantum Dot Film With Bridge Patterns to Enhance Luminance of LED Backlight Unit
Abstract:
An integrated prism sheet on quantum dot (QD) film with bridge patterns has been proposed to increase the optical efficiency of an LED backlight unit. The bridge patterns were designed, such that they not only extract the light trapped in a QD film but also change the optical path effectively toward the vertical direction. We verified our design concept and geometrical parameters by optical simulation, and fabricated the integrated optical sheet using a lithography and UV imprinting process. The simulation results show the luminance enhancement of 33.6% after applying the bridge patterns while keeping the same Commission Internationale de l’Éclairage (CIE) after careful controlling the concentration of QDs. The enhancement of luminance toward the vertical directionwas also confirmed experimentally after the fabrication of an integrated prism sheet on a QD enhancement film.
Autors: Se-Eun Kim;Jae-Yong Lee;Min-Ho Shin;Hyo-Jun Kim;Young-Joo Kim;
Appeared in: IEEE Transactions on Electron Devices
Publication date: Mar 2017, volume: 64, issue:3, pages: 1153 - 1160
Publisher: IEEE
 
» Integration [From the Editor's Desk]
Abstract:
Presents the introductory editorial for this issue of the publication.
Autors: Alfy Riddle;
Appeared in: IEEE Microwave Magazine
Publication date: Mar 2017, volume: 18, issue:2, pages: 6 - 8
Publisher: IEEE
 
» Intelligent Interactive Displays in Vehicles with Intent Prediction: A Bayesian framework
Abstract:
Using an in-vehicle interactive display, such as a touch screen, typically entails undertaking a freehand pointing gesture and dedicating a considerable amount of attention, that can be otherwise available for driving, with potential safety implications. Due to road and driving conditions, the user's input can also be subject to high levels of perturbations resulting in erroneous selections. In this article, we give an overview of the novel concept of an intelligent predictive display in vehicles. It can infer, notably early in the pointing task and with high confidence, the item the user intends to select on the display from the tracked freehand pointing gesture and possibly other available sensory data. Accordingly, it simplifies and expedites the target acquisition (pointing and selection), thereby substantially reducing the time and effort required to interact with an in-vehicle display. As well as briefly addressing the various signal processing and human factor challenges posed by predictive displays in the automotive environment, the fundamental problem of intent inference is discussed, and a Bayesian formulation is introduced. Empirical evidence from data collected in instrumented cars is shown to demonstrate the usefulness and effectiveness of this solution.
Autors: Bashar I. Ahmad;James Kevin Murphy;Simon Godsill;Patrick M. Langdon;Robery Hardy;
Appeared in: IEEE Signal Processing Magazine
Publication date: Mar 2017, volume: 34, issue:2, pages: 82 - 94
Publisher: IEEE
 
» Interactive Exploration of Cosmological Dark-Matter Simulation Data
Abstract:
The winning entry of the 2015 IEEE Scientific Visualization Contest, this article describes a visualization tool for cosmological data resulting from dark-matter simulations. The proposed system helps users explore all aspects of the data at once and receive more detailed information about structures of interest at any time. Moreover, novel methods for visualizing and interactively exploring dark-matter halo substructures are proposed.
Autors: Aaron Scherzinger;Tobias Brix;Dominik Drees;Andreas Völker;Kiril Radkov;Niko Santalidis;Alexander Fieguth;Klaus H. Hinrichs;
Appeared in: IEEE Computer Graphics and Applications
Publication date: Mar 2017, volume: 37, issue:2, pages: 80 - 89
Publisher: IEEE
 
» Interarea Oscillations Revisited
Abstract:
This letter revisits interarea oscillation analysis using networked control analysis techniques. The power system analysis problem is analyzed as a networked control problem, specifically consensus control of homogeneous systems with static output feedback. The power grid is represented by a graph Laplacian matrix. Stability of the entire system can be evaluated by individual system dynamics and graph Laplacian's eigenvalues. Through this technique, the classical large-scale power system analysis problem is decomposed into multiple small-scale system analysis problems. Analysis of the classical two-area four-machine system is conducted by the proposed approach and compared with the small-signal analysis results from Power System Toolbox. The interarea oscillation mode is found to be related to the second smallest eigenvalue of the graph Laplacian matrix, while the local oscillation modes are related to the other eigenvalues of the graph Laplacian matrix.
Autors: Lingling Fan;
Appeared in: IEEE Transactions on Power Systems
Publication date: Mar 2017, volume: 32, issue:2, pages: 1585 - 1586
Publisher: IEEE
 
» Intercloud: Solving Interoperability and Communication in a Cloud of Clouds (Frahim, J., et al; 2016) [Book Review]
Abstract:
The ability to share resources, services, responsibility, and management among cloud providers is the fundamental ssumption from the viewpoint of cloud interoperability. This idea is attracting increasing attention as cloud providers are becoming aware that meeting all customer needs without any cooperation is a demanding task. This book regards the issues of seamless and transparent cloud interoperability. Definitions, architectures, and use cases are provided, along with challenges and threats. The book is divided into nine chapters. The book presents the concepts, needs, advantages, and challenges regarding cloud interoperability. The assumed high level approach will be most suitable for readers responsible for technology assessment and service development. The authors provide business-level concepts, architectures, and data about standardization efforts. However, the covered practical use cases and workflow examples will also be attractive for network and IT managers. Timeliness is also undoubtedly a strong aspect of the book. Two minor drawbacks must be mentioned. The first one regards the organization of the book, and some improvements in this context will make the book more readable. The second issue concerns Chapters 2 and 5, as both could have been improved to be more easily comprehended by readers. Nevertheless, in summary, the book is recommended as a good and up-do-date source of information on cloud interoperability.
Autors: Piotr Borylo;
Appeared in: IEEE Communications Magazine
Publication date: Mar 2017, volume: 55, issue:3, pages: 6 - 6
Publisher: IEEE
 
» Interconnected Multi-1-D FADI- and FLOD-FDTD Methods for Transmission Lines With Interjunctions
Abstract:
This paper presents the interconnected multi-1-D (IM1-D) fundamental alternating-direction-implicit finite-difference time-domain (FADI-FDTD) and fundamental locally 1-D finite-difference time-domain (FLOD-FDTD) methods for transmission lines with interjunctions. The proposed methods are unconditionally stable and capable of treating multiple main transmission lines and stubs interconnected at various interjunctions using time step larger than Courant–Friedrichs–Lewy limit. Fundamental scheme-based IM1-D FADI- and FLOD-FDTD methods are derived to enhance the efficiency with matrix-operator-free right-hand sides. The methods involve one-step update procedure optimized for simulation of main transmission lines and stubs on mobile device. Using proper treatments at the interjunctions for various interconnection conditions, the electromagnetic fields in all interconnected main transmission lines and stubs can be updated cooperatively and efficiently to solve practical problems. A microstrip line loaded with stubs and a branch-line coupler are simulated to show the accuracy and efficiency of the proposed methods. To extend the applicability for handling the couplings between two transmission lines via gaps, a microstrip circuit with gaps is simulated using the proposed methods incorporated with equivalent circuit models involving capacitances. Real-time simulations of these numerical examples provide much intuitional insight for one to observe the electromagnetic waves propagation in time domain on computer or mobile device.
Autors: Zaifeng Yang;Eng Leong Tan;
Appeared in: IEEE Transactions on Microwave Theory and Techniques
Publication date: Mar 2017, volume: 65, issue:3, pages: 684 - 692
Publisher: IEEE
 
» Interconnection Allocation Between Functional Units and Registers in High-Level Synthesis
Abstract:
Data path interconnection on VLSI chips usually consumes a significant amount of both power and area. In this paper, we focus on the port assignment problem for binary commutative operators for interconnection complexity reduction. First, the port assignment problem is formulated on a constraint graph, and a practical method is proposed to find a valid and initial solution. For solution optimization, an elementary spanning-tree-transformation-based local search algorithm is proposed. To improve the efficiency of optimization, a matrix formulation, which meets the simplex tabuleau format, is proposed and thus the simplex method is adopted for optimization. Moreover, operation pivoting and successive pivoting are discussed for algorithm speedup. The experimental results show that on the randomly generated test cases, the matrix-based algorithm shows the highest solution optimality and is five times faster than the elementary transformation method. On the real high-level synthesis benchmarks, the matrix-based method reduced 14% interconnections, while the previous greedy algorithm reduced 8% on average.
Autors: Cong Hao;Jianmo Ni;Nan Wang;Takeshi Yoshimura;
Appeared in: IEEE Transactions on Very Large Scale Integration Systems
Publication date: Mar 2017, volume: 25, issue:3, pages: 1140 - 1153
Publisher: IEEE
 
» Interference and SINR in Millimeter Wave and Terahertz Communication Systems With Blocking and Directional Antennas
Abstract:
The fifth generation wireless systems are expected to rely on a large number of small cells to massively offload traffic from the cellular and even from the wireless local area networks. To enable this functionality, mm-wave (EHF) and Terahertz (THF) bands are being actively explored. These bands are characterized by unique propagation properties compared with microwave systems. As a result, the interference structure in these systems could be principally different to what we observed so far at lower frequencies. In this paper, using the tools of stochastic geometry, we study the systems operating in the EHF/THF bands by explicitly capturing three phenomena inherent for these frequencies: 1) high directivity of the transmit and receive antennas; 2) molecular absorption; and 3) blocking of high-frequency radiation. We also define and compare two different antenna radiation pattern models. The metrics of interest are the mean interference and the signal-to-interference-plus-noise (SINR) ratio at the receiver. Our results reveal that: 1) for the same total emitted energy by a Poisson field of interferers, both the interference and SINR significantly increase when simultaneously both transmit and receive antennas are directive and 2) blocking has a profound impact on the interference and SINR creating much more favorable conditions for communications compared with no blocking case.
Autors: Vitaly Petrov;Mikhail Komarov;Dmitri Moltchanov;Josep Miquel Jornet;Yevgeni Koucheryavy;
Appeared in: IEEE Transactions on Wireless Communications
Publication date: Mar 2017, volume: 16, issue:3, pages: 1791 - 1808
Publisher: IEEE
 
» Interleaved Isophoric Sparse Arrays for the Radiation of Steerable and Switchable Beams in Satellite Communications
Abstract:
We address the synthesis of isophoric sparse ring arrays for full-Earth coverage from Geostationary Earth Orbit (GEO) satellites by means of steerable beams, switchable between two different widths. In particular, we pursue the desired beam zooming/shrinking through two interleaved sparse arrays deployed over the available circular aperture. To this aim, we propose two different antenna architectures. In one case, the two beams are radiated by two separate interleaved arrays; in the other case, the two beams are instead radiated by two interleaved arrays that share a common part of their layouts. Both the proposed architectures allow us to exploit a synthesis procedure that calculates the two interleaved arrays separately, through the cascade of two steps, both implemented with a (computationally) very efficient deterministic density-tapering approach. The proposed strategy allows to obtain isophoric sparse layouts, satisfying the required design constraints with a significant reduction of the control points with respect to the solution achievable exploiting noninterleaved isophoric sparse arrays.
Autors: Ovidio Mario Bucci;Stefano Perna;Daniele Pinchera;
Appeared in: IEEE Transactions on Antennas and Propagation
Publication date: Mar 2017, volume: 65, issue:3, pages: 1163 - 1173
Publisher: IEEE
 
» Intermittent Connection Fault Diagnosis for CAN Using Data Link Layer Information
Abstract:
Controller area networks (CANs) had been applied to many safety critical applications, hence the reliability of the CAN network becomes increasingly important. Due to the aging of the cable connections and inappropriate maintenance, the intermittent connection (IC) problem of network cables will occur on the CAN network over time, which will affect the system performance, deteriorate the reliability and safety of the system. Hence, effective detection and accurate localization of the IC fault are crucial to the system reliability assurance. In this paper, a novel IC fault localization algorithm for CAN-based systems is proposed, which utilizes the data link layer information of the CAN network for IC fault pattern analysis. First, the fault events are defined by comparing the detected error records. Second, the context free grammar is used to represent the IC faults based on network topology information. Then, based on the node error event pattern correlation, the concurrent localization algorithm is proposed to localize the local and backbone IC faults. Testbed is constructed and case studies are conducted to demonstrate the proposed methodology under various fault scenarios. Experiment results show that the IC fault locations identified by the proposed method agree well with the experiment setup.
Autors: Leiming Zhang;Yong Lei;Qing Chang;
Appeared in: IEEE Transactions on Industrial Electronics
Publication date: Mar 2017, volume: 64, issue:3, pages: 2286 - 2295
Publisher: IEEE
 
» Internet of Things: Part 3
Abstract:
Autors: Christos Verikoukis;Roberto Minerva;Mohsen Guizani;Soumya Kanti Datta;Yen-Kuang Chen;Hausi A. Muller;
Appeared in: IEEE Communications Magazine
Publication date: Mar 2017, volume: 55, issue:3, pages: 108 - 109
Publisher: IEEE
 
» Interval Homogeneity-Based Control for a Class of Nonlinear Systems With Unknown Power Drifts
Abstract:
This technical note considers the global stabilization problem for a class of nonlinear systems with unknown power (exponent) drifts. Based on the concept of interval homogeneity with monotone degrees, the allowable bounds of the unknown power drifts can be explicitly determined to guarantee the solvability of the problem. The technique of adding a power integrator is revamped based on a new Lyapunov function with interval parameters and is recursively employed to construct a global stabilizer for the nonlinear systems.
Autors: Zhigang Su;Chunjiang Qian;Jiong Shen;
Appeared in: IEEE Transactions on Automatic Control
Publication date: Mar 2017, volume: 62, issue:3, pages: 1445 - 1450
Publisher: IEEE
 
» Intratidal Overdistention and Derecruitment in the Injured Lung: A Simulation Study
Abstract:
Goal: Ventilated patients with the acute respiratory distress syndrome (ARDS) are predisposed to cyclic parenchymal overdistention and derecruitment, which may worsen existing injury. We hypothesized that intratidal variations in global mechanics, as assessed at the airway opening, would reflect such distributed processes. Methods: We developed a computational lung model for determining local instantaneous pressure distributions and mechanical impedances continuously during a breath. Based on these distributions and previous literature, we simulated the within-breath variability of airway segment dimensions, parenchymal viscoelasticity, and acinar recruitment in an injured canine lung for tidal volumes() of 10, 15, and 20 mL·kg−1 and positive end-expiratory pressures (PEEP) of 5, 10, and 15 cm H2O. Acini were allowed to transition between recruited and derecruited states when exposed to stochastically determined critical opening and closing pressures, respectively. Results: For conditions of low and low PEEP, we observed small intratidal variations in global resistance and elastance, with a small number of cyclically recruited acini. However, with higher and PEEP, larger variations in resistance and elastance were observed, and the majority of acini remained open throughout the breath. Changes in intratidal resistance, elastance, and impedance followed well-defined parabolic trajectories with tracheal pressure, achieving minima near 12 to 16 cm H2O. Conclusion: Intratidal variations in lung mechanics may allow for optimization of ventila or settings in patients with ARDS, by balancing lung recruitment against parenchymal overdistention. Significance: Titration of airway pressures based on variations in intratidal mechanics may mitigate processes associated with injurious ventilation.
Autors: Reza Amini;Jacob Herrmann;David W. Kaczka;
Appeared in: IEEE Transactions on Biomedical Engineering
Publication date: Mar 2017, volume: 64, issue:3, pages: 681 - 689
Publisher: IEEE
 
» Introducing Optical Cascode GaN HEMT
Abstract:
A novel optically activated cascode gallium nitride (GaN) high-electron-mobility transistor (HEMT) is introduced and evaluated in this paper. Furthermore, optical triggering of GaN HEMT structures by cost-effective and high-power long-wavelength light sources is proposed for the first time. In electrical domain, GaN HEMTs suffer from being normally on devices, making it more complicated to design and implement gate drivers for these devices. In optical domain, GaN devices suffer from being triggered by low-power short-wavelength light sources, making them significantly more expensive and practically unprofitable. Therefore, a new optical cascode (OC) GaN HEMT is proposed in this paper to solve the problems of both electrical and optical domains. The structure of this OC GaN HEMT includes a high-power normally on (depletion mode) GaN HEMT in combination with a low-power optical switch in cascode configuration. This OC not only realizes an overall normally off (enhancementmode) structure, but also offers activationwith cost-effective long-wavelength optical sources. It also offers a single-biased configurationwithout the need for complicated electrical gate drivers. Unlike conventional electrically activated cascode GaN HEMT structures, which may be prone to electromagnetic interference noise due to the high-frequency switching operation, the optical link in this proposed scheme is immune to external noise. The results showa high-frequency switching capability of 1MHz for theOCGaN HEMT under a bias voltage of 600 V and a current of 10 A. Less voltage and current ringing are observed in the OC compared with the electrical alternative due to the elimination of gate controlling inductance introduced in the electrical cascode configuration.
Autors: Alireza Mojab;Zahra Hemmat;Hossein Riazmontazer;Arash Rahnamaee;
Appeared in: IEEE Transactions on Electron Devices
Publication date: Mar 2017, volume: 64, issue:3, pages: 796 - 804
Publisher: IEEE
 
» Introducing the IEEE Signal Processing Society Executive Committee [President's Message]
Abstract:
Presents a listing of the IEEE Signal Processing Society Executive Committee.
Autors: Rabab Ward;
Appeared in: IEEE Signal Processing Magazine
Publication date: Mar 2017, volume: 34, issue:2, pages: 5 - 6
Publisher: IEEE
 
» Introduction to the Special Issue on Time/Frequency Modulated Array Signal Processing
Abstract:
The papers in this special section focus on time/frequency modulated array signal processing. Phased-array is known for its capability to electronically steer a beam towards a desired direction. However, this beam steering does not account for the target range. There is an increasing need to control the range-dependent transmit energy distribution in applications involving interference suppression, directional communications, and range ambiguity. Towards this end, several advanced array design approaches have been introduced, which include time modulated array (TMA), frequency diverse array (FDA), and frequency diversity or time division based multiple-input multiple-output (MIMO) systems. This special issue (SI) covers a variety of signal processing approaches, all based on time/frequency modulated arrays. It aims to compile relevant research contributions from various disciplines, including statistical signal processing for radar and communications, antenna array design and synthesis, and applied mathematics.
Autors: Hing Cheung So;Moeness G. Amin;Shannon Blunt;Fulvio Gini;Wen-Qin Wang;
Appeared in: IEEE Journal of Selected Topics in Signal Processing
Publication date: Mar 2017, volume: 11, issue:2, pages: 225 - 227
Publisher: IEEE
 
» Investigation into Limitation of Arc Erosion in LV Switches Through Application of Hybrid Switching
Abstract:
In this paper, measurement results of the arc erosion limitation in low voltage (LV) switches are presented. The reduction of the arc erosion in the analyzed electromechanical switches was achieved through an application of the hybrid switching in the tested alternative current circuit during interruption of the inductive current. The presented method is based on a commutation of the current during its interruption into a semiconductor branch that is connected in parallel to the operated switch. Thus, this approach is able to limit the electric arc energy efficiently, and as a consequence the arc erosion of the electrical contacts is also significantly reduced. For this reason, the application of the hybrid switching has a positive influence on a lifespan and a reliability of the operated switch. In order to evaluate the influence of the hybrid switching application on an effectiveness of the limitation of the arc erosion in the analyzed LV switches, 50 000 current interruptions were conducted in the tested circuit by each of four analyzed switches. Researches were performed for two standalone switches during a standard current interruption, as well as, for two switches with applied the hybrid switching system. In order to compare the arc erosion of the contact surfaces in both considered cases, scanning electron microscope method coupled with energy dispersion spectroscopy was applied. Moreover, photos of the electric contact surfaces are presented. Additionally, frames registered by high-speed camera during current interruption are presented for both considered approaches.
Autors: Piotr Oramus;Marek Florkowski;Andrzej Rybak;Jolanta Sroka;
Appeared in: IEEE Transactions on Plasma Science
Publication date: Mar 2017, volume: 45, issue:3, pages: 446 - 453
Publisher: IEEE
 
» Investigation Into Loss Reduced Rotor Slot Structure by Analyzing Local Behaviors of Harmonic Magnetic Fluxes in Inverter-Fed Induction Motor
Abstract:
We analyzed the local behaviors of both time and space harmonic magnetic fluxes in this research to improve the efficiency of inverter-fed induction motors. As a result, we clarified that: the magnetic flux of time harmonics passes in parallel through rotor bars and the magnetic flux of space harmonics passes radially through the rotor bars from the delay side in the direction of rotation. We propose a new rotor slot structure to reduce harmonic losses by taking these results into consideration. We also manufactured a prototype that was applied to the proposed structure of rotor slots, and measured motor losses. Consequently, although the current was increased by 2%, the total loss under inverter driven condition in induction motor was reduced by 20% with the proposed structure under the equal output power of 1.1 MW.
Autors: Naoki Kunihiro;Kazuo Nishihama;Motonobu Iizuka;Kenichi Sugimoto;Masanori Sawahata;
Appeared in: IEEE Transactions on Industry Applications
Publication date: Mar 2017, volume: 53, issue:2, pages: 1070 - 1077
Publisher: IEEE
 
» Investigation of In Situ SiN as Gate Dielectric and Surface Passivation for GaN MISHEMTs
Abstract:
In this paper, we present a systematic investigation of metal–organic chemical vapor deposition-grown in situ SiN as the gate dielectric and surface passivation for AlGaN/GaN metal insulator semiconductor high electron mobility transistors (MISHEMTs). The dielectric constant and breakdown field of the in situ SiN were extracted from devices with varied gate dielectric thicknesses. Using frequency-dependent capacitance–voltage and parallel conductance methods, we obtained a low trap density of cmeV at the SiN/AlGaN interface. The MISHEMTs with a source–drain distance of show a maximum drain current of 1560 mA/mm and a high on/off current ratio of . The device threshold voltage () stability was assessed by means of both negative and positive gate stress measurements, as well as temperature-dependent – measurements. We observed a minimal shift of ~0.4 V under both 3000 s gate stress of V and up to 200 °C thermal stimulation. Furthermore, combining the in situ SiN with plasma-enhanced chemical vapor deposition SiN, we developed a bilayer passivation scheme for effective suppression of current collapse. Employing the high-quality in situ SiN, we have demonstrated large-area GaN MISHEMTs on Si with a gate width of 20 mm, showing a low off-state leakage of /mm at 600 V and a low dynamic/static ON-resistance ratio. The device results show great advantages of employing in situ SiN in D-mode GaN MISHEMTs for high-efficiency power switching applications.
Autors: Huaxing Jiang;Chao Liu;Yuying Chen;Xing Lu;Chak Wah Tang;Kei May Lau;
Appeared in: IEEE Transactions on Electron Devices
Publication date: Mar 2017, volume: 64, issue:3, pages: 832 - 839
Publisher: IEEE
 
» Investigation of Near-Field Radiative Heat Transfer of Multilayered Structures in Heat-Assisted Magnetic Recording
Abstract:
Near-field radiation effects in heat-assisted magnetic recording (HAMR) are important to contribute the heat transfer and hence the flying ability at the head disk interface. Investigation of the near-field heat transfer is essential to optimize the head disk interface. An equivalent simulation model of the head disk interface for studying the radiative heat transfer is provided in this paper. Both the head shape and the magnetic properties of material are considered in this paper. The dyadic Green’s functions along with fluctuational electrodynamics as well as scatter matrix are employed to calculate the heat transfer at the head disk interface. The head is simplified as a nanosphere, while the disk is simplified as a semi-infinite multilayered structures, in which the thickness of all layers is in nanoscale. The results show that the near-field radiative heat transfer between the head and disk in HAMR can exceed the values predicted by the Planck blackbody calculation by a few orders of magnitude. The total power is found to exponentially increase when the distance between the head and disk decreases.
Autors: Yu Zhao;Longqiu Li;Hongtao Zhang;Guangbin Shao;Qingkang Liu;
Appeared in: IEEE Transactions on Magnetics
Publication date: Mar 2017, volume: 53, issue:3, pages: 1 - 6
Publisher: IEEE
 
» Investigation of Self-Heating Effect on Ballistic Transport Characterization for Si FinFETs Featuring Ultrafast Pulsed IV Technique
Abstract:
In this paper, we investigate the carrier transport characteristics of the ultrascaled Si FinFETs. Traditional dc characterization technique is compared with the ultrafast pulsed IV method. Due to the severe self-heating effect introduced in the characterization process, the ballistic transport parameters extracted using dc method would show essential discrepancies from those in the real high-speed IC circuits. Therefore, an ultrafast pulsed IV measurement technique is proposed for accurate ballistic transport characterization. Furthermore, since the series resistance () of the Si FinFETs is temperature-dependent, a modified backscattering model is adopted to extract the ballistic transport parameters without the influence of the temperature-variant . A ballisticity scaling model was established to predict the scalability of the ballistic transport parameters. It is found that very high ballisticity could be achieved for FinFETs with sub-10-nm technology nodes.
Autors: Ran Cheng;Xiao Yu;Bing Chen;Junfeng Li;Yiming Qu;Jinghui Han;Rui Zhang;Yi Zhao;
Appeared in: IEEE Transactions on Electron Devices
Publication date: Mar 2017, volume: 64, issue:3, pages: 909 - 915
Publisher: IEEE
 
» Investigation on the Graphitization Process of Amorphous Carbon for HAMR by Molecular Dynamics Simulation
Abstract:
Molecular dynamics simulations are performed to investigate the laser-induced graphitization of amorphous carbon (a-C) films at different densities for heat-assisted magnetic recording. Physical insights into the graphitization caused by laser heating are provided by analyzing the virial pressure, bond angle distribution, radial distribution function, pair distribution function, and atomic strains during the laser heating and cooling process. The effects of density and laser irradiation times on the graphitization of a-C films are investigated. The laser-induced ultrafast nonthermal phase transformation occurs in the heating process. The sp3–sp2 transformation is mainly contributed by the atoms in sp3–sp3 bonds both in the heating and cooling process. Less energy is required for those atoms to overcome the energy barrier. The atomic shear strains and volume strains can accelerate the sp3–sp2 transformation. For all a-C films at different densities, the rate of sp2-hybridized atoms increases rapidly in the first laser irradiation process.
Autors: Qingkang Liu;Longqiu Li;Hongtao Zhang;Qitao Huang;Guangyu Zhang;Zhenxiu Hou;
Appeared in: IEEE Transactions on Magnetics
Publication date: Mar 2017, volume: 53, issue:3, pages: 1 - 7
Publisher: IEEE
 
» Investigation on Thermal Characterization of Eutectic Flip-Chip UV-LEDs With Different Bonding Voidage
Abstract:
Flip-chip ultraviolet light-emitting diode (FC UV-LED) fabricated by direct AuSn eutectic package is of high interest in Research and Development due to its excellent thermal performance and good reliability. However, the voids in eutectic bonding layer due to the lack of AuSn filled have a big influence on the thermal management and optical performance of FC UV-LEDs, and it is believed that the eutectic voids can affect the thermal-conduction resistance (the following unified called thermal resistance) and the junction temperature of FC UV-LEDs. In this paper, modeling and thermal simulation using finite element analysis is developed by considering the geometrical model of eutectic FC UV-LEDs with 3%, 10%, 20%, and 30% bonding voidage. Meanwhile, to validate the simulation, the thermal parameters of FC UV-LEDs are determined and measured using thermal transient tester, and it is found that UV-LED with 3% voidage shows lowest thermal resistance and junction temperature compared with the other samples in both simulation and experiment. Moreover, the optical performance of UV-LEDs is evaluated via the photoelectric analysis system, and the results confirm that the lowest thermal resistance leads to the lowest junction temperature but the highest light output power.
Autors: Renli Liang;Jun Zhang;Shuai Wang;Qian Chen;Linlin Xu;Jiangnan Dai;Changqing Chen;
Appeared in: IEEE Transactions on Electron Devices
Publication date: Mar 2017, volume: 64, issue:3, pages: 1174 - 1179
Publisher: IEEE
 
» Iron-Loss and Magnetic Hysteresis Under Arbitrary Waveforms in NO Electrical Steel: A Comparative Study of Hysteresis Models
Abstract:
This paper presents a comparative study of different static hysteresis models coupled to the parametric magneto-dynamic model of soft magnetic steel sheets. Both mathematical and behavioral as well as physically based approaches are discussed with respect to the ability to predict the dynamic hysteresis loop shape and iron loss under arbitrary excitation waveforms. Both current- as well as voltage-driven excitation cases are evaluated. The presented analysis discusses and points out advantages and limitations of the majority of the well-known static hysteresis models. In this way, it supports the selection of adequate hysteresis models for the specific application, i.e., smooth excitations, distorted flux waveforms, transients, or steady-state regimes. Comparisons against measurements for a M400-50A electrical steel over a wide range of magnetic flux density and frequencies for both sinusoidal and arbitrary excitations are analyzed. In the analysis hysteresis loop shapes, power losses as well as NRMS errors of individual loop sections are compared.
Autors: Simon Steentjes;Kay Hameyer;Drago Dolinar;Martin Petrun;
Appeared in: IEEE Transactions on Industrial Electronics
Publication date: Mar 2017, volume: 64, issue:3, pages: 2511 - 2521
Publisher: IEEE
 
» IRSL: Iterative Refining Superpixel Lattice
Abstract:
This letter presents a new method to generate superpixel lattice. Unlike the existing methods based on strip seaming, it iteratively refines an initial lattice to achieve an expected lattice. In each iteration, it adjusts local lattice step by step. At each step, a vertex and its four connecting edges are refined by finding the optimal horizontal and vertical edges. The optimal edges are found by dynamic programming technique. This method is tested against both remotely sensed images and standard data set dedicated to segmentation evaluation. The proposed method is better or competitive with the existing state-of-the-art superpixel lattice methods concerning both performance and efficiency.
Autors: Dengfeng Chai;Yating Huang;Yangjie Bao;
Appeared in: IEEE Geoscience and Remote Sensing Letters
Publication date: Mar 2017, volume: 14, issue:3, pages: 344 - 348
Publisher: IEEE
 
» ISAR Imaging of Maneuvering Target Based on the Quadratic Frequency Modulated Signal Model With Time-Varying Amplitude
Abstract:
Inverse synthetic aperture radar (ISAR) imaging of maneuvering target plays an important role in the field of national defense and surveillance. In this case, the conventional range Doppler algorithm is unsuitable to generate a well-focused ISAR image due to the time-varying property of the Doppler frequency during the integrated imaging interval. Furthermore, the dihedral or trihedral components of the imaging target or the phenomena of migration through resolution cell for the target's complex motion will induce the time-varying performance of the amplitude for the received signal. In this paper, the received signal in a range bin is depicted as multicomponent quadratic frequency-modulated signal with time-varying amplitude, and the generalized cubic phase function is used to estimate the parameters of it. Associated with the range instantaneous Doppler technique, the images quality can be enhanced distinctly compared with the conventional constant amplitude signal model. Results of simulated and read data demonstrate the effectiveness of the novel algorithm proposed in this paper.
Autors: Yong Wang;Rongqing Xu;Qingxiang Zhang;Bin Zhao;
Appeared in: IEEE Journal of Selected Topics in Applied Earth Observations and Remote Sensing
Publication date: Mar 2017, volume: 10, issue:3, pages: 1012 - 1024
Publisher: IEEE
 
» Iterative LDPC–LDPC Product Code for Bit Patterned Media
Abstract:
Bit patterned media aims at high density recording of more than 10 Tb per square inch, but a burst error mostly occurred by media defects, and data write failure can be a serious problem. However, if the burst errors are compensated by erasure decoding, the performance of low-density parity check (LDPC) code, which is a strong candidate for the error correcting code for storage systems, can be improved. In this paper, we propose an iterative LDPC–LDPC product code and show that it performs better than a simple LDPC–LDPC product code when there are only random errors and both random and burst errors.
Autors: Seongkwon Jeong;Jaejin Lee;
Appeared in: IEEE Transactions on Magnetics
Publication date: Mar 2017, volume: 53, issue:3, pages: 1 - 4
Publisher: IEEE
 
» Iterative Matrix Decomposition Aided Block Diagonalization for mm-Wave Multiuser MIMO Systems
Abstract:
Considering the dearth for spectrum in the congested microwave band, the next generation of cellular communication systems is envisaged to incorporate part of the millimeter wave (mm-wave) band. Hence, recently, there has been a significant interest in beamforming aided mm-wave systems. We consider a downlink multiuser mm-wave system employing a large number of antennas combined with fewer radio frequency chains both at the base station (BS) and at each of the user equipments (UEs). The BS and each of the UE are assumed to have a hybrid beamforming architecture, where a set of analog phase shifters is followed by digital precoding/combining blocks. In this paper, we propose an iterative matrix decomposition based hybrid beamforming (IMD-HBF) scheme for a single-user scenario, which accurately approximates the unconstrained beamforming solution, we show that the knowledge of the angle of departure (AoD) of the various channel paths is sufficient for the block diagonalization (BD) of the downlink mm-wave channel and hence for achieving interference free channels for each of the UEs, we propose a novel subspace projection based AoD aided BD (SP-AoD-BD) that achieves significantly better performance than the conventional BD, while still only requiring the knowledge of the AoD of various channel paths, and we use IMD-HBF in order to employ SP-AoD-BD in the hybrid beamforming architecture and study its performance with respect to the unconstrained system. We demonstrate using simulation results that the proposed IMD-HBF gives the same spectral efficiency as that of the unconstrained system in the single user scenario. Furthermore, we study the achievable sum rate of the users, when employing SP-AoD-BD with the aid of IMD-HBF and show that the loss in the performance with respect to the unconstrained system as well as the existing schemes is negligible, provided that the number of users is not excessive.
Autors: Rakshith Rajashekar;Lajos Hanzo;
Appeared in: IEEE Transactions on Wireless Communications
Publication date: Mar 2017, volume: 16, issue:3, pages: 1372 - 1384
Publisher: IEEE
 
» JackIn Head: Immersive Visual Telepresence System with Omnidirectional Wearable Camera
Abstract:
Sharing one's own immersive experience over the Internet is one of the ultimate goals of telepresence technology. In this paper, we present JackIn Head, a visual telepresence system featuring an omnidirectional wearable camera with image motion stabilization. Spherical omnidirectional video footage taken around the head of a local user is stabilized and then broadcast to others, allowing remote users to explore the immersive visual environment independently of the local user's head direction. We describe the system design of JackIn Head and report the evaluation results of real-time image stabilization and alleviation of cybersickness. Then, through an exploratory observation study, we investigate how individuals can remotely interact, communicate with, and assist each other with our system. We report our observation and analysis of inter-personal communication, demonstrating the effectiveness of our system in augmenting remote collaboration.
Autors: Shunichi Kasahara;Shohei Nagai;Jun Rekimoto;
Appeared in: IEEE Transactions on Visualization and Computer Graphics
Publication date: Mar 2017, volume: 23, issue:3, pages: 1222 - 1234
Publisher: IEEE
 
» Joint Backhaul-Access Analysis of Full Duplex Self-Backhauling Heterogeneous Networks
Abstract:
With the successful demonstration of in-band full-duplex (IBFD) transceivers, a new research dimension has been added to wireless networks. This paper proposes a use case of this capability for IBFD self-backhauling heterogeneous networks (HetNets). IBFD self-backhauling in a HetNet refers to IBFD-enabled small cells backhauling themselves with macro cells over the wireless channel. Owing to their IBFD capability, the small cells simultaneously communicate over the access and backhaul links, using the same frequency band. The idea is doubly advantageous, as it obviates the need for fiber backhauling small cells every hundred meters and allows the access spectrum to be reused for backhauling at no extra cost. This paper considers the case of a two-tier cellular network with IBFD-enabled small cells, wirelessly backhauling themselves with conventional macro cells. For clear exposition, the case considered is that of the Frequency Division Duplexing (FDD) network, where within access and backhaul links, the downlink (DL) and uplink are frequency duplexed (, respectively), while the total frequency spectrum used at access and backhaul () is the same. Analytical expressions for coverage and average DL rate in such a network are derived using tools from the field of stochastic geometry. It is shown that DL rate in such networks could be close to double that of a conventional TDD/FDD self-backhauling network, at the expense of reduced coverage due to higher interference in IBFD networks. For the proposed IBFD network, the conflicting aspects of increased interference on one side and high spectral efficiency on the other are captured into a mathematical model. The mathematical model introduces an end-to-end joint analysis of - ackhaul (or fronthaul) and access links, in contrast to the largely available access-centric studies.
Autors: Ankit Sharma;Radha Krishna Ganti;J. Klutto Milleth;
Appeared in: IEEE Transactions on Wireless Communications
Publication date: Mar 2017, volume: 16, issue:3, pages: 1727 - 1740
Publisher: IEEE
 
» Joint Energy Detection and Massive Array Design for Localization and Mapping
Abstract:
The adoption of massive arrays for simultaneous localization and mapping or personal radar applications enables the possibility to detect and localize surrounding objects through an accurate beamforming procedure. Unfortunately, when a classical constant false alarm rate approach accounting for ideal-pencil beam pattern is adopted, ambiguities in signal detection could arise due to the presence of side-lobes which can cause non-negligible errors in target detection and ranging. To counteract such effect, in this paper we propose a joint threshold-array design approach, where the antenna characteristics are taken into account to best set the threshold and to guarantee the desired detection and ranging performance at the non-coherent receiver section. In order to consider realistic arrays impairments, we focus our attention on the number of antenna elements and of phase shifter bits used for beamforming as key players in defining a trade-off between structural complexity, well-defined radiation pattern, and localization performance. Simulation and measurement results show that the number of bits per phase shifter can be relaxed in favor of a simpler array design, if the number of antennas is sufficiently high and the side-lobes are kept within a suitable level allowing a desired robustness to interference signals.
Autors: Francesco Guidi;Anna Guerra;Davide Dardari;Antonio Clemente;Raffaele D’Errico;
Appeared in: IEEE Transactions on Wireless Communications
Publication date: Mar 2017, volume: 16, issue:3, pages: 1359 - 1371
Publisher: IEEE
 
» Joint Millimeter-Wave Fronthaul and OFDMA Resource Allocation in Ultra-Dense CRAN
Abstract:
Ultra-dense (UD) wireless networks and cloud radio access networks (CRAN) are two promising network architectures for the emerging fifth-generation wireless communication systems. By jointly employing them, a new appealing network solution is proposed in this paper, termed UD-CRAN. In a UD-CRAN, millimeter-wave (mmWave) wireless fronthaul is preferred for information exchange between the central processor and the distributed remote radio heads (RRHs), due to its lower cost and higher flexibility in deployment, compared with fixed optical links. This motivates our study in this paper on the downlink transmission in a mmWave fronthaul enabled, orthogonal frequency division multiple access (OFDMA)-based UD-CRAN. In particular, the fronthaul is shared among the RRHs via time division multiple access (TDMA), while the RRHs jointly transmit to the users on orthogonal frequency sub-channels using OFDMA. The joint resource allocation over the TDMA-based mmWave fronthaul and OFDMA-based wireless transmission is investigated to maximize the weighted sum rate of all users. Although the problem is non-convex, we propose a Lagrange duality-based solution, which can be efficiently computed with good accuracy. To further reduce the complexity, we also propose a greedy search-based heuristic, which achieves close to optimal performance under practical setups. Finally, we show the significant throughput gains of the proposed joint resource allocation approach compared with other benchmark schemes by simulations.
Autors: Reuben George Stephen;Rui Zhang;
Appeared in: IEEE Transactions on Communications
Publication date: Mar 2017, volume: 65, issue:3, pages: 1411 - 1423
Publisher: IEEE
 
» Joint Power Allocation and Strategy Selection for Half-Duplex Relay System
Abstract:
Decode and forward (DF) and compress and forward (CF) are two efficient cooperation strategies for relay networks. The combination of the DF and CF strategies is promising to improve the achievable rate of cooperative communication systems. To thoroughly aggregate the advantage of the DF and CF strategies, we put forward a joint power allocation and strategy selection (PASS) scheme for the half-duplex relay channel. The PASS scheme is shown to achieve a higher rate compared with a regular hybrid DF/CF scheme. The rate gain obtained in the static relay channel results from actively adjusting and optimizing the relay power, followed by selecting the better strategy between DF and CF. In particular, when the relay receives and transmits in sequential time slots, we characterize the positive rate improvement area of the PASS scheme analytically and give a near-optimal setting for approaching the best rate performance. The PASS scheme is extended to fading relay channels. We show that the rate increment obtained from the PASS scheme is further magnified by employing an advanced relay power allocation technique over channel states. The corresponding optimal power allocation is established based on the concavity of the rate achieved by the PASS scheme in static relay channel. Numerical results are presented to validate the analysis.
Autors: Zhengchuan Chen;Pingyi Fan;Dapeng Oliver Wu;
Appeared in: IEEE Transactions on Vehicular Technology
Publication date: Mar 2017, volume: 66, issue:3, pages: 2144 - 2157
Publisher: IEEE
 
» Joint Relay–User Beamforming Design in a Full-Duplex Two-Way Relay Channel
Abstract:
A full-duplex (FD) two-way relay channel (TWRC) with multiple antennas is considered. For this three-node network, the beamforming design needs to suppress self-interference (SI). While a traditional way is to apply zero forcing (ZF) for SI mitigation, it may harm the desired signals. In this paper, a design that reserves a fraction of SI is proposed by solving a quality-of-service (QoS) constrained beamforming design problem. Since the problem is challenging due to the loop SI, a convergence-guaranteed alternating optimization (AO) algorithm is proposed to jointly design the relay–user beamformers. Numerical results show that the proposed scheme outperforms ZF method and achieves a transmit power value close to the ideal case.
Autors: Zhigang Wen;Shuai Wang;Xiaoqing Liu;Junwei Zou;
Appeared in: IEEE Transactions on Vehicular Technology
Publication date: Mar 2017, volume: 66, issue:3, pages: 2874 - 2879
Publisher: IEEE
 
» Joint Source and Relay Precoding Design for MIMO Two-Way Relay Systems With Transceiver Impairments
Abstract:
Physical transceiver impairments can degrade the performance of wireless communication systems significantly. Although partial impairments can be mitigated by some compensation algorithms, residual impairments still have substantial effects. In this letter, we investigate the joint source/relay precoding design for the multiple-input multiple-output two-way amplify and forward relay systems by considering hardware impairments. Unlike the ideal case, considering the effect of hardware impairments makes the precoding design more challenging. To tackle the problem, we use certain rules of trace operator to convert the original design problem and develop an iterative algorithm to find a local optimal solution. Simulation results show that the system is more sensitive to hardware impairments in the high signal noise ratio regimes and neglect of the residual hardware impairments will deteriorate the system performance significantly.
Autors: Jiayi You;Erwu Liu;Rui Wang;Weideng Su;
Appeared in: IEEE Communications Letters
Publication date: Mar 2017, volume: 21, issue:3, pages: 572 - 575
Publisher: IEEE
 
» Joint Uplink Radio Access and Fronthaul Reception Using MMSE Estimation
Abstract:
In cloud-based radio access networks, remote radio units and central baseband units are connected by fronthaul links, which are commonly assumed to be error-free. However, especially for wireless millimeter wave fronthaul links, this might be challenging to achieve, as they face a more unreliable environment than the conventionally used fiber links. In this paper, we hence aim to mitigate the impact of imperfect fronthaul links. For this, we propose the concept of joint radio access and fronthaul reception, which considers to recover the transmitted messages correctly at the centralized baseband unit, rather than to ensure a nearly perfect fronthaul transmission in between. Based on the Bayesian minimum mean square error criterion, we develop a joint access and fronthaul estimation scheme that can be utilized for various signals transported over the fronthaul, including in-phase/quadrature phase (I/Q) samples, soft-bits, synchronization, and reference signals. In addition, we develop an approximated variant of the scheme to reduced complexity, and an iterative extension to further improve the performance. We demonstrate that our scheme can operate under less reliable fronthaul than conventional approaches by numerical simulation for different signals, and show that our method can be implemented in a parallel architecture to achieve a reasonable computational complexity.
Autors: Jens Bartelt;Dan Zhang;Gerhard Fettweis;
Appeared in: IEEE Transactions on Communications
Publication date: Mar 2017, volume: 65, issue:3, pages: 1366 - 1378
Publisher: IEEE
 
» Joint Video Packet Scheduling, Subchannel Assignment and Power Allocation for Cognitive Heterogeneous Networks
Abstract:
In this paper, a joint video scheduling, subchannel assignment, and power allocation problem in cognitive heterogeneous networks are modeled as a mixed integer non-linear programming (MINLP), which maximizes the minimum video transmission quality among different secondary mobile terminals (MTs) subject to the total available energy at each secondary, the total interference power at each primary base station, the total available capacity at each radio interface of each secondary MTs, and the video sequence encoding characteristic. In order to solve it, we decompose the original MINLP as joint subchannel and power allocation problem and video packet scheduling problem. Then, we model the joint subchannel and power allocation problem as a max–min fractional programming, and transform it as a convex optimization problem. Finally, we utilize dual decomposition method to design a joint subchannel and power allocation algorithm, and propose a video packet scheduling scheme based on auction theory to maximize the video quality for each secondary MT. Simulation results demonstrate that the proposed framework not only improves the video transmission quality significantly, but also guarantees the fairness among different secondary MTs.
Autors: Lei Xu;Arumugam Nallanathan;Xiaoqin Song;
Appeared in: IEEE Transactions on Wireless Communications
Publication date: Mar 2017, volume: 16, issue:3, pages: 1703 - 1712
Publisher: IEEE
 
» Joint Admission Control and Routing Via Approximate Dynamic Programming for Streaming Video Over Software-Defined Networking
Abstract:
This paper considers the optimization problem of joint admission control and routing for the video streaming service in wired software-defined networking (SDN). With the aid of the network operating system, SDN is able to support the dynamic nature of future network functions and intelligent applications. Against this changing network landscape, we rely on FlowVisor-based virtualization in the context of OpenFlow-based wired SDN to design an open optimization architecture for the joint admission control and routing, which supports flexible and agile deployment of advanced joint admission control and routing strategies. Following this architecture, we interpret the joint admission control and routing problem into the Markov decision process for maximizing the overall “revenue.” In order to solve the issue of the curses of dimensionality, we invoke the function approximation technique in the context of approximate dynamic programming to conceive an online learning framework. By applying kernel-based autonomous feature extraction into the function approximation, we develop an approximate dynamic programming-based joint admission control and routing for video streaming service, which is apt to be implemented in the proposed open architecture. An emulation platform based on FlowVisor, POX, and Mininet is constructed for demonstrating the success of the proposed solution. The experimental results are presented to show the performance improvement of the proposed scheme by comparing it with the Q-learning algorithm and open shortest path first-based benchmark scheme.
Autors: Jian Yang;Kunjie Zhu;Yongyi Ran;Weizhe Cai;Enzhong Yang;
Appeared in: IEEE Transactions on Multimedia
Publication date: Mar 2017, volume: 19, issue:3, pages: 619 - 631
Publisher: IEEE
 
» Kalman Filter Based Detection and Mitigation of Subsynchronous Resonance with SSSC
Abstract:
In a long transmission line the use of static series synchronous compensation (SSSC) with fixed series capacitor enables fast control of power flow. There is a potential risk of subsynchronous resonance (SSR) due to the series capacitor. In this paper, we propose to use the Kalman filter (KF) for state estimation of subsynchronous components present in series compensated line and the mitigation of SSR. This novel KF based SSR damping controller is referred to as KF-damping controller. The design of KF-damping controller is based on the magnitude of damping torque in the range of torsional mode frequencies. We apply the genetic algorithm to optimize the controller parameters. The proposed KF-damping controller is highly frequency selective and effectively suppresses subsynchronous components of line current in the presence of close frequency oscillations. Analytical and simulation results at various system operating conditions demonstrate the effectiveness and robustness of the proposed KF-damping controller in mitigating SSR.
Autors: Thirumalaivasan Rajaram;Janaki Muneappa Reddy;Yunjian Xu;
Appeared in: IEEE Transactions on Power Systems
Publication date: Mar 2017, volume: 32, issue:2, pages: 1400 - 1409
Publisher: IEEE
 
» Kalman Filter Based Estimation of Auditory Steady State Response Parameters
Abstract:
Auditory steady state responses (ASSRs) are brain responses to modulated or repetitive stimuli that can be captured in the EEG recording. ASSRs can be used as an objective measure to clinically determine frequency specific hearing thresholds, to quantify the sensitivity of the auditory system to modulation, and have been related to speech intelligibility. However, the detection of ASSRs is difficult due to the low signal to noise ratio of the responses. Moreover, minimizing measurement time is important for clinical applications. Traditionally ASSRs are analyzed using discrete Fourier transform (DFT) based methods. We present a Kalman filter based ASSR analysis procedure and illustrate several benefits over traditional DFT based methods. We show on a data set of 320 measurements that the proposed method reaches valid amplitude estimates significantly faster than the state of the art DFT method. Further, we provide two extensions to the proposed method. First, we demonstrate information can be incorporated from multiple recording electrodes by extending the system model. Secondly, we extend the model to incorporate artifacts from cochlear implant (CI) stimulation and demonstrate electrically evoked auditory steady state responses (EASSRs) can be accurately measured.
Autors: Robert Luke;Jan Wouters;
Appeared in: IEEE Transactions on Neural Systems and Rehabilitation Engineering
Publication date: Mar 2017, volume: 25, issue:3, pages: 196 - 204
Publisher: IEEE
 
» KDE-Track: An Efficient Dynamic Density Estimator for Data Streams
Abstract:
Recent developments in sensors, global positioning system devices, and smart phones have increased the availability of spatiotemporal data streams. Developing models for mining such streams is challenged by the huge amount of data that cannot be stored in the memory, the high arrival speed, and the dynamic changes in the data distribution. Density estimation is an important technique in stream mining for a wide variety of applications. The construction of kernel density estimators is well studied and documented. However, existing techniques are either expensive or inaccurate and unable to capture the changes in the data distribution. In this paper, we present a method called KDE-Track to estimate the density of spatiotemporal data streams. KDE-Track can efficiently estimate the density function with linear time complexity using interpolation on a kernel model, which is incrementally updated upon the arrival of new samples from the stream. We also propose an accurate and efficient method for selecting the bandwidth value for the kernel density estimator, which increases its accuracy significantly. Both theoretical analysis and experimental validation show that KDE-Track outperforms a set of baseline methods on the estimation accuracy and computing time of complex density structures in data streams.
Autors: Abdulhakim Qahtan;Suojin Wang;Xiangliang Zhang;
Appeared in: IEEE Transactions on Knowledge and Data Engineering
Publication date: Mar 2017, volume: 29, issue:3, pages: 642 - 655
Publisher: IEEE
 
» Kernel Regularized Data Uncertainty for Action Recognition
Abstract:
The traditional data uncertainty (DU) classifier fails to encode the importance of each sample for solving the minimum problem. Moreover, it considers only linear information for classification. To overcome these, we propose four classifiers for action recognition. They are called regularized DU (RDU) classifier, RDU coefficient (RDUC) classifier, kernel RDU (KRDU) classifier, and kernel RDUC (KRDUC) classifier, respectively. Extensive experiments on four benchmark action databases demonstrate that the proposed four classifiers achieve better recognition rates than the traditional DU classifier and several state-of-the-art methods. Moreover, the computation costs of the KRDU and KRDUC classifiers are much less than that of the DU classifier.
Autors: Qingxiang Feng;Yicong Zhou;
Appeared in: IEEE Transactions on Circuits and Systems for Video Technology
Publication date: Mar 2017, volume: 27, issue:3, pages: 577 - 588
Publisher: IEEE
 
» Kinematic Bilateral Teledriving of Wheeled Mobile Robots Coupled With Slippage
Abstract:
With the increasing applications of wheeled mobile robots (WMRs) in various fields, some new challenges have arisen on designing its teleoperation system. One of such challenges is caused by wheel's slippage. This paper proposes a new approach for haptic teledriving of a WMR coupled with slippage. In this teleoperation system, the WMR's linear velocity and angular velocity, respectively, follow the master haptic interface's positions. The proposed teleoperation controller also includes an acceleration-level control law for the WMR so that the WMR's linear and angular velocity loss induced by the slippage can be compensated for. Information caused by wheel's slippage in the environment termination (ET) is displayed to the human operator through haptic (force) feedback. After designing a local controller to compensate for the ET's nonpassivity caused by the slippage, the system's stability is shown via its passivity and it is also shown that the force felt by the human operator is approximately equal to the output force of the ET. Experiments of the proposed controller demonstrate that the modified ET is passive and the controller can result in stable bilateral teleoperation with a satisfactory tracking performance.
Autors: Weihua Li;Liang Ding;Zhen Liu;Weidong Wang;Haibo Gao;Mahdi Tavakoli;
Appeared in: IEEE Transactions on Industrial Electronics
Publication date: Mar 2017, volume: 64, issue:3, pages: 2147 - 2157
Publisher: IEEE
 
» Laplacian LRR on Product Grassmann Manifolds for Human Activity Clustering in Multicamera Video Surveillance
Abstract:
In multicamera video surveillance, it is challenging to represent videos from different cameras properly and fuse them efficiently for specific applications such as human activity recognition and clustering. In this paper, a novel representation for multicamera video data, namely, the product Grassmann manifold (PGM), is proposed to model video sequences as points on the Grassmann manifold and integrate them as a whole in the product manifold form. In addition, with a new geometry metric on the product manifold, the conventional low rank representation (LRR) model is extended onto PGM and the new LRR model can be used for clustering nonlinear data, such as multicamera video data. To evaluate the proposed method, a number of clustering experiments are conducted on several multicamera video data sets of human activity, including the Dongzhimen Transport Hub Crowd action data set, the ACT 42 Human Action data set, and the SKIG action data set. The experiment results show that the proposed method outperforms many state-of-the-art clustering methods.
Autors: Boyue Wang;Yongli Hu;Junbin Gao;Yanfeng Sun;Baocai Yin;
Appeared in: IEEE Transactions on Circuits and Systems for Video Technology
Publication date: Mar 2017, volume: 27, issue:3, pages: 554 - 566
Publisher: IEEE
 
» Large-Scale Automated Software Diversity—Program Evolution Redux
Abstract:
The software monoculture favors attackers over defenders, since it makes all target environments appear similar. Code-reuse attacks, for example, rely on target hosts running identical software. Attackers use this assumption to their advantage by automating parts of creating an attack. This article presents large-scale automated software diversification as a means to shore up this vulnerability implied by our software monoculture. Besides describing an industrial-strength implementation of automated software diversity, we introduce methods to objectively measure the effectiveness of diversity in general, and its potential to eliminate code-reuse attacks in particular.
Autors: Andrei Homescu;Todd Jackson;Stephen Crane;Stefan Brunthaler;Per Larsen;Michael Franz;
Appeared in: IEEE Transactions on Dependable and Secure Computing
Publication date: Mar 2017, volume: 14, issue:2, pages: 158 - 171
Publisher: IEEE
 
» Large-Scale Binary Quadratic Optimization Using Semidefinite Relaxation and Applications
Abstract:
In computer vision, many problems can be formulated as binary quadratic programs (BQPs), which are in general NP hard. Finding a solution when the problem is of large size to be of practical interest typically requires relaxation. Semidefinite relaxation usually yields tight bounds, but its computational complexity is high. In this work, we present a semidefinite programming (SDP) formulation for BQPs, with two desirable properties. First, it produces similar bounds to the standard SDP formulation. Second, compared with the conventional SDP formulation, the proposed SDP formulation leads to a considerably more efficient and scalable dual optimization approach. We then propose two solvers, namely, quasi-Newton and smoothing Newton methods, for the simplified dual problem. Both of them are significantly more efficient than standard interior-point methods. Empirically the smoothing Newton solver is faster than the quasi-Newton solver for dense or medium-sized problems, while the quasi-Newton solver is preferable for large sparse/structured problems.
Autors: Peng Wang;Chunhua Shen;Anton van den Hengel;Philip H. S. Torr;
Appeared in: IEEE Transactions on Pattern Analysis and Machine Intelligence
Publication date: Mar 2017, volume: 39, issue:3, pages: 470 - 485
Publisher: IEEE
 
» Large-Scale Dynamic Controller Placement
Abstract:
The controller placement problem (CPP) is one of the key challenges of software defined networks (SDNs) to increase performance. Given the locations of switches, CPP consists of choosing the controller locations that minimize the latency between switches and SDN controllers. In its current form, however, CPP assumes a fixed traffic and no existing solutions adapt the placement to the load. In this paper, we have addressed the dynamic CPP that consists of: 1) determining the locations of controller modules to bound communication latencies and 2) determining the number of controllers per module to support the dynamic load. We propose an algorithm named LiDy+ that runs in and combines a controller module placement algorithm with a dynamic flow management algorithm. We evaluate the number of controllers, the controller utilization, and the power consumption and the maintenance cost of LiDy+ on both sparse and dense networks. Our comparison against a previous solution shows that LiDy+ does not only achieve a smaller number of controllers and a higher controller utilization but also incurs less energy and maintenance costs than the previous solution. Finally, we run LiDy+ in a large-scale environment where the previous solution of time complexity is impractical.
Autors: Md Tanvir Ishtaique ul Huque;Weisheng Si;Guillaume Jourjon;Vincent Gramoli;
Appeared in: IEEE Transactions on Network and Service Management
Publication date: Mar 2017, volume: 14, issue:1, pages: 63 - 76
Publisher: IEEE
 

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