Electrical and Electronics Engineering publications abstract of: 11-2017 sorted by title, page: 7

» Effects of DC Bias Current on Behavior and Sensitivity of Thin-Film Magnetoimpedance Element
Abstract:
We investigated the behaviors and sensitivity of thin-film magnetoimpedance elements having an easy axis angle of 0°–45° when applying dc bias current directly to the elements. All elements show symmetric impedance profiles with respect to the impedance axis without dc bias current, while their profiles become asymmetric with dc bias current. This appearance of the asymmetric property on the impedance profiles indicates that the shape of cross section of the element has asymmetric configuration. On the other hand, when the easy axis angle is relatively small, the sensitivity for field detection is enhanced with a small dc bias level, while a stronger bias level is required for the element with a larger easy axis angle. The obtained results show a potential to optimize the sensor properties by dc bias current with small intensity in case that design properties are not obtained in the fabrication process.
Autors: H. Kikuchi;C. Sumida;T. Nakai;S. Hashi;K. Ishiyama;
Appeared in: IEEE Transactions on Magnetics
Publication date: Nov 2017, volume: 53, issue:11, pages: 1 - 4
Publisher: IEEE
 
» Effects of Electrical and Optogenetic Deep Brain Stimulation on Synchronized Oscillatory Activity in Parkinsonian Basal Ganglia
Abstract:
Conventional deep brain stimulation of basal ganglia uses high-frequency regular electrical pulses to treat Parkinsonian motor symptoms but has a series of limitations. Relatively new and not yet clinically tested, optogenetic stimulation is an effective experimental stimulation technique to affect pathological network dynamics. We compared the effects of electrical and optogenetic stimulation of the basal gangliaon the pathologicalParkinsonian rhythmic neural activity. We studied the network response to electrical stimulation and excitatory and inhibitory optogenetic stimulations. Different stimulations exhibit different interactions with pathological activity in the network. We studied these interactions for different network and stimulation parameter values. Optogenetic stimulation was found to be more efficient than electrical stimulation in suppressing pathological rhythmicity. Our findings indicate that optogenetic control of neural synchrony may be more efficacious than electrical control because of the different ways of how stimulations interact with network dynamics.
Autors: Shivakeshavan Ratnadurai-Giridharan;Chung C. Cheung;Leonid L. Rubchinsky;
Appeared in: IEEE Transactions on Neural Systems and Rehabilitation Engineering
Publication date: Nov 2017, volume: 25, issue:11, pages: 2188 - 2195
Publisher: IEEE
 
» Effects of Glycine in DES-Based Plating Baths on Structural and Magnetic Properties of Fe–Ni Films
Abstract:
We have already reported that a deep eutectic solvent is one of hopeful solvents to obtain an electroplated Fe-based soft magnetic film since the plating process shows high current efficiency. In this paper, we employed glycine as an additive to improve surface roughness and soft magnetic properties of electroplated Fe–Ni films. The coercivity of the Fe-rich films (>70 at.%) prepared from the glycine-used bath showed lower values compared with those for the no-glycine baths. From the evaluations for the surface roughness and the crystal structure of the as-plated Fe75Ni25 films, we considered that the reductions in the coercivity of the Fe-rich films for the glycine-used baths are attributed to the smooth surface and the reduction in the effective crystalline anisotropy by increase in the volume fraction of an amorphous magnetic phase in the film.
Autors: T. Yanai;T. Yamaguchi;T. Akiyoshi;K. Takashima;M. Nakano;H. Fukunaga;
Appeared in: IEEE Transactions on Magnetics
Publication date: Nov 2017, volume: 53, issue:11, pages: 1 - 4
Publisher: IEEE
 
» Effects of Liner Thickness on the Reliability of AgTe/TiO2-Based Threshold Switching Devices
Abstract:
The effects of liner thickness on the reliability of AgTe/TiO2-based threshold switching (TS) devices were investigated. The off-state current of an AgTe/TiO2/Pt TS device was found to be significantly increased by in-diffusion of Ag into the TiO2 layer during the annealing process. Therefore, 3-, 5- and 7-nm TiN liners were introduced and compared to prevent the in-diffusion of Ag. While the 3-nm TiN liner was shown to be incapable of blocking Ag in-diffusion into the TiO2 layer, the 5- and 7-nm liners effectively suppressed in-diffusion and maintained high off-state resistance. However, the TS device with the 7-nm TiN liner exhibited wide threshold voltage distribution and poor endurance characteristics owing to a lack of Ag sources. The TS device with a 5-nm TiN liner, by contrast, was found to have an adequate amount of Ag sources and to demonstrate thermally stable and electrically reliable characteristics. The effects of TiN liner on Ag diffusion were also directly confirmed using energy dispersive spectrometry line profiles, transmission electron microscopy imaging, and mapping analyses.
Autors: Jeonghwan Song;Jiyong Woo;Jongmyung Yoo;Solomon Amsalu Chekol;Seokjae Lim;Changhyuck Sung;Hyunsang Hwang;
Appeared in: IEEE Transactions on Electron Devices
Publication date: Nov 2017, volume: 64, issue:11, pages: 4763 - 4767
Publisher: IEEE
 
» Effects of Pt Buffer Layer and Sr Content on Multiferroic (Bi, Sr)FeO3 Polycrystalline Thin Films on Glass Substrates
Abstract:
Effects of Pt buffer layer and Sr content on the structure, surface morphology, ferroelectric, and magnetic properties of Bi1-xSrxFeO3 (BSFO) polycrystalline films on glass substrates at reduced temperature of 450 °C have been investigated. Perovskite single phase is present in the studied BSFO films (–0.15) on 10–30 nm thick Pt(111) electrodes. The grain size and surface roughness of BSFO films is closely related to the morphology of Pt(111) electrodes. Further refined microstructure with reduced surface roughness is found with the increase of Sr content . BSFO polycrystalline thin films display good ferroelectric properties with the remanent polarization (2Pr) of 77–103 /cm2 and electrical coercive field ( of 380–490 kV/cm. In addition, the enhanced ferromagnetic properties with magnetization () of 8.7–11.2 emu/cm3 and coercivity () of 1211–1299 Oe are attained.
Autors: H. W. Chang;C. Y. Shen;F. T. Yuan;Y. C. Lo;S. Y. Lin;C. F. Chang;C. R. Wang;C. S. Tu;S. U. Jen;W. C. Chang;
Appeared in: IEEE Transactions on Magnetics
Publication date: Nov 2017, volume: 53, issue:11, pages: 1 - 4
Publisher: IEEE
 
» Effects of Silicon Content on the Properties of Gas-Atomized Fe–Si–Cr Powders
Abstract:
Fe-7%, 8%, 9%, and 11%Si–Cr powders were gas atomized and then annealed at 25 °C–750 °C to investigate the effects of Si content, DO3 phase, and B2 phase on the high-frequency permeability of the powders. The formation of the B2 phase could not be suppressed during the atomization process of all the powders. The evolution temperatures of the DO3 phase in the Fe-7%, 8%, and 9%Si–Cr powders as measured by X-ray diffractometer were 550 °C, 550 °C, and 450 °C, respectively. As the annealing temperature was increased, the DO3 phase grew rapidly, and the lattice parameters of the powders were decreased except for those of the Fe-11%Si–Cr powder. The coercivity of all powders decreased with increasing temperature; however, the coercivity of the Fe-8%, 9%Si–Cr powders increased sharply after annealing at 450 °C. Permeability decreased rapidly with increasing temperature except for the Fe-11%Si–Cr powder; thus, the highest real permeability was obtained for the as-atomized Fe-8%Si–Cr powder. The changes in the coercivity and permeability of the powders with annealing temperature could be attributed to the evolution of the DO3 phase, Si segregation, and changes in electrical resistivity.
Autors: Pyungwoo Jang;Gwangbo Choi;
Appeared in: IEEE Transactions on Magnetics
Publication date: Nov 2017, volume: 53, issue:11, pages: 1 - 5
Publisher: IEEE
 
» Efficiency, Stability, and Reliability Implications of Unbalanced Current Sharing Among Distributed On-Chip Voltage Regulators
Abstract:
Power delivery networks with distributed on-chip voltage regulators (VRs) serve as an effective way for fast localized voltage regulation within modern microprocessors. Without careful consideration of the interactions among the distributed VRs and the power grid, unbalanced current sharing (CS) among those regulators may, however, lead to efficiency degradations, stability, and reliability issues, and even malfunctions of the regulators. This paper is a first attempt to investigate the efficiency, stability, and reliability implications of unbalanced CS among distributed on-chip VRs. Benefits of balanced CS are demonstrated with concrete examples, showing the necessity of an appropriate current balancing scheme. An adaptive reference voltage control method and the corresponding control algorithms specifically for distributed on-chip VRs are proposed to balance the CS among regulators at different locations. The proposed techniques successfully balance the CS among distributed VRs and can be applied to different regulator types. Simulation results based on practical microprocessor setups confirm the efficiency, stability, and reliability implications.
Autors: Longfei Wang;S. Karen Khatamifard;Orhun Aras Uzun;Ulya R. Karpuzcu;Selçuk Köse;
Appeared in: IEEE Transactions on Very Large Scale Integration Systems
Publication date: Nov 2017, volume: 25, issue:11, pages: 3019 - 3032
Publisher: IEEE
 
» Efficient Data Center Flow Scheduling Without Starvation Using Expansion Ratio
Abstract:
Existing data center transport protocols are usually based on the Processor Sharing (PS) policy and/or the Shortest Remaining Processing Time (SRPT) policy. PS divides link bandwidth equally between competing flows, thus it fails to achieve optimal average flow completion time (FCT). SRPT prioritizes flows that have the shortest remaining processing time and provides near-optimal average FCT, but it may cause long flows to suffer unfair delays, or even starve them. In fact, these two types of policies represent two directions in the design space: PS prefers fairness (in terms of starvation freedom) while SRPT favors efficiency (in terms of average FCT). In this paper, we propose a novel metric, expansion ratio, which enables us to strike a balance between SRPT and PS. We design MERP that achieves efficient flow scheduling without starvation. MERP takes care of both average and tail FCTs by minimizing the expansion ratio of competing flows in a lexicographically manner. MERP controls the sending rate of competing flows via synchronized virtual deadlines and routes flows in a downstream-aware manner that reacts quickly to link failures. We evaluate MERP using extensive NS2-based simulations. Results show that, under various traffic loads, MERP reduces the tail FCT significantly with a negligible increase of average FCT compared with pFabric, and MERP reduces the average FCT notably compared with ECMP and CONGA when link failures occur.
Autors: Sheng Zhang;Zhuzhong Qian;Hao Wu;Sanglu Lu;
Appeared in: IEEE Transactions on Parallel and Distributed Systems
Publication date: Nov 2017, volume: 28, issue:11, pages: 3157 - 3170
Publisher: IEEE
 
» Efficient Evaluation of Multichannel SAR Data Recombination Filters
Abstract:
Synthetic aperture radar (SAR) is a well-established technique for observing the Earth on a global scale. As applications become more demanding, it is desirable to overcome the limitations imposed by the SAR principle, one of which is the tradeoff between the swath width and the instantaneous azimuth bandwidth, determining the resolution. Recombination of multiple channels with displaced phase centers has been proposed as a convenient way to create high resolution wide-swath images. We analyze various approximations made in the channel transfer functions and their impact on the reconstruction result using examples inspired by current imaging modes of the TerraSAR-X and TanDEM-X missions. In order to do so, we introduce an efficient method to assess the quality of reconstruction filters for an arbitrary number of channels without the need of full time-domain simulations.
Autors: Moritz Kiemer;Helko Breit;
Appeared in: IEEE Transactions on Geoscience and Remote Sensing
Publication date: Nov 2017, volume: 55, issue:11, pages: 6277 - 6286
Publisher: IEEE
 
» Efficient Method for Scattering From Cylindrical Components of Vegetation and Its Potential Application to the Determination of Effective Permittivity
Abstract:
Reliable and efficient analysis of electromagnetic scattering by cylindrical components of vegetation is important for microwave remote sensing of vegetated terrain. It allows for the characterization of anistropicity of the effective permittivity for vegetation or tree canopy, where averaging operation over distribution of cylinder orientation is needed in general. In this paper, we propose a T-matrix formulation based on our virtual partition method (VPM) for the whole cylindric component of either homogeneous or inhomogeneous nature. Numerical simulations demonstrate that the proposed T-matrix preserves all the desirable features of the VPM method, including high fidelity prediction of the scattering amplitude function and fulfillment of energy conservation as well as the reciprocity theorem. More importantly, in the evaluation of averaging over orientation distribution, the proposed method is usually faster than the VPM by two orders of magnitude. The predicted effective permittivity for an exemplary orientation distribution shows appreciable difference from that of the infinite cylinder approximation. With its qualitatively characterized region of validity, the proposed method is expected to be helpful in multiband coherent scattering models of vegetated terrain.
Autors: Dejun Li;Chao Yang;Yang Du;
Appeared in: IEEE Transactions on Geoscience and Remote Sensing
Publication date: Nov 2017, volume: 55, issue:11, pages: 6120 - 6127
Publisher: IEEE
 
» Efficient Resource Allocation in Device-to-Device Communication Using Cognitive Radio Technology
Abstract:
Device-to-device (D2D) communication is developed as a new paradigm to enhance network performance according to LTE and WiMAX advanced standards. The D2D communication may have dedicated spectrum (overlay) or shared spectrum (underlay). However, the allocated dedicated spectrum may not be effectively used in the overlay mode, while interference between the D2D users and cellular users cause impairments in the underlay mode. Can the resource allocation of a D2D system be optimized using the cognitive approach where the D2D users opportunistically access the underutilized radio spectrum? That is the focus of this paper. In this paper, the transmission rate of the D2D users is optimized while simultaneously satisfying five sets of constraints related to power, interference, and data rate, modeling D2D users as cognitive secondary users. Furthermore, a two-stage approach is considered to allocate the radio resources efficiently. A new adaptive subcarrier allocation scheme is designed first, and then, a novel power allocation scheme is developed utilizing geometric water-filling approach that provides optimal solution with low computation complexity for this nonlinear problem. Numerical results show that the proposed approach achieved significant performance enhancement than the existing schemes.
Autors: Ajmery Sultana;Lian Zhao;Xavier Fernando;
Appeared in: IEEE Transactions on Vehicular Technology
Publication date: Nov 2017, volume: 66, issue:11, pages: 10024 - 10034
Publisher: IEEE
 
» Elastic versus WDM networks with dedicated multicast protection
Abstract:
We consider the routing and spectrum allocation (RSA) problem of protecting all-optical multicast sessions against a single link failure in elastic optical networks (EONs). A tree is derived to support a multicast session and can be considered as a set of paths originating from a common source. We use a scheme to protect each of the paths by an arc-disjoint backup path in the case of any link failure. For this problem, we provide a node-arc integer linear programming (ILP) formulation and propose a heuristic algorithm for this protection scheme. We evaluate the improvement achieved by the flexible grids adopted in EONs over the fixed-grid wavelength-division multiplexing (WDM) networks. The evaluation is done by considering static modeling based on ILP and heuristics as well as dynamic simulations. We consider two approaches for heuristic algorithms: one is a two-step (TS) approach that computes the routing trees then allocates spectrum. The other uses the spectrum window plane (SWP) and constructs auxiliary graphs for the relevant range of spectrum to jointly solve the RSA problem. We evaluate the performances of the proposed algorithms under static and dynamic traffic models. Based on the studied scenarios, we observe consistent improvement in efficiency of flexible grid EONs over fixed-grid WDM networks. Moreover, we demonstrate that the network size (likely because of the availability of more alternative routes) can significantly affect the benefit in efficiency achieved by the SWP-based approaches over the TS approaches.
Autors: Anliang Cai;Zheyu Fan;Kai Xu;Moshe Zukerman;Chun-Kit Chan;
Appeared in: IEEE/OSA Journal of Optical Communications and Networking
Publication date: Nov 2017, volume: 9, issue:11, pages: 921 - 933
Publisher: IEEE
 
» Electric Field Tuning Ferromagnetic Resonance Frequency Shift in Oblique Sputtered Fe42Co46Hf12/PZN-PT Multiferroic Heterostructures
Abstract:
Strong inverse magnetoelectric (ME) coupling was observed in Fe42Co46Hf12/Lead Zinc Niobate–Lead Titanate multiferroic heterostructure, which produced a large electric field (E-field) tunability on microwave magnetic properties. With the increase of the E-field from 0 to 8 kV/cm, the E-field-dependent linearly increases from 175 to 411 Oe, equivalent to a large ME tunability of /kV, which further leads to a significant enhancement of ferromagnetic resonance frequency from 4.13 to 6.28 GHz under zero bias magnetic field. These features demonstrate that this multiferroic composite is a promising candidate for fabricating E-field-tunable microwave components.
Autors: Shandong Li;Xiaomin Liu;Honglei Du;Qiang Li;Jie Xu;Xia Wang;Hwaider Lin;Nian X. Sun;
Appeared in: IEEE Transactions on Magnetics
Publication date: Nov 2017, volume: 53, issue:11, pages: 1 - 4
Publisher: IEEE
 
» Electrical and Methanol Sensing Characteristics of RF Sputtered n-ZnO/p-Si Heterojunction Diodes
Abstract:
This paper reports structural, electrical, and gas sensing characteristics of n-ZnO/p-Si heterojunction diodes fabricated using RF sputtering technique. The microstructural and surface morphological properties have been studied using X-ray diffraction, atomic force microscopy, and scanning electron microscopy, respectively. The electrical properties of the fabricated diodes have been investigated using current-voltage (–) and capacitance-voltage (–) measurements. The estimated values for rectification ratio, ideality factor, and barrier height were found to be ~100, 3.27, and 0.72eV, respectively, at room temperature. The values recorded for carrier concentration and barrier height using – measurement were cm and 0.79 eV, respectively. The value of series resistance using Chueng’s function was found to be 1710 . After detailed structural and electrical characterization, methanol sensing response (3–100 ppm) of n-ZnO/p-Si heterojunction diodes for the temperature range of 27 °C–150 °C have also been investigated. The optimum operating temperature for methanol sensing was found to be considerably low,- i.e., 100 °C. The values of response magnitude, response time and recovery time at 100 °C were estimated as 82%, ~4 and ~7 s, respectively. The cross sensitivity study for the nearest interfering species, such as ethanol, 1-propanol, butanol, butanone, and benzene, has confirmed the high selectivity of n-ZnO/p-Si heterojunction diodes for methanol sensing.
Autors: Shashi Kant Sharma;Basanta Bhowmik;Vipin Pal;Chinnamuthan Periasamy;
Appeared in: IEEE Sensors Journal
Publication date: Nov 2017, volume: 17, issue:22, pages: 7332 - 7339
Publisher: IEEE
 
» Electrical Balance Duplexer Field Trials in High-Speed Rail Scenarios
Abstract:
Electrical balance duplexers (EBDs) present a potential alternative to the fixed-frequency duplexing filters used for frequency division duplexing in cellular handset radio frequency front ends. However, the transmit-to-receive (Tx–Rx) isolation can be affected by interaction between the antenna and the environment, and therefore, the EBDs balancing impedance must adaptively track time-domain antenna impedance variation. A rail scenario presents a potentially demanding use case for an EBD, as fast moving trains in the vicinity of the antenna may cause dynamically changing reflections, which can be received as self-interference. In this paper, measured dynamic antenna reflection coefficients at 745 and 1900 MHz from train mounted antennas are included in the EBD circuit simulations in order to investigate the resulting variation in Tx–Rx isolation, and determine requirements for balancing impedance adaptation. This paper also presents the results from rail-based field trials of a hardware prototype EBD, which implements real-time antenna impedance tracking. Results show that the rail scenario does result in variation in Tx–Rx isolation, but that rebalancing the EBD at the intervals of 5 ms was sufficient to maintain >50 dB isolation for ~95% of the time.
Autors: Leo Laughlin;Chunqing Zhang;Mark A. Beach;Kevin A. Morris;John L. Haine;
Appeared in: IEEE Transactions on Antennas and Propagation
Publication date: Nov 2017, volume: 65, issue:11, pages: 6068 - 6075
Publisher: IEEE
 
» Electrical Impedance Myography for Evaluating Paretic Muscle Changes After Stroke
Abstract:
Electrical impedance myography (EIM) was used to assess the paretic muscle intrinsic electrical properties post stroke. Twenty-seven subjects with chronic hemiparesis participated in this study. Muscle impedance was measured by applying high-frequency, low-intensity alternating current to biceps brachii muscles. Major EIM parameters, resistance (), reactance (), phase angle (), and electrical anisotropy ratios (AR) of the three parameters, were examined at 50 kHz. Statistical analysis demonstrated significant reduction of reactance, phase angle, AR of resistance, and AR of reactance in the paretic muscle compared with the contralateral side (Paretic X: , contralateral X: , and p < 0.001; Paretic : , contralateral : 14.5 ± 0.82°, and p < 0.001; Paretic AR of R: 0.969 ± 0.013, contralateral AR of R: 1.008 ± 0.011, and p < 0.02; and Paretic AR of X: 0.981 ± 0.066, contralateral AR of X: 1.114 ± 0.041, and p < 0.02). Correlation analysis, however, did not show any significant relationship between EIM parameters and clinical assessments. Findings of this paper indicate- significant changes in the muscular intrinsic electrical properties after stroke, possibly related to structural modifications induced by loss of muscle fibers or fat infiltration as well as changes in the quality of cell membranes post stroke.
Autors: Xiaoyan Li;Le Li;Henry Shin;Sheng Li;Ping Zhou;
Appeared in: IEEE Transactions on Neural Systems and Rehabilitation Engineering
Publication date: Nov 2017, volume: 25, issue:11, pages: 2113 - 2121
Publisher: IEEE
 
» Electrical Impedance Tomography: Tissue Properties to Image Measures
Abstract:
Electrical impedance tomography (EIT) uses electrical stimulation and measurement at the body surface to image the electrical properties of internal tissues. It has the advantage of noninvasiveness and high temporal resolution but suffers from poor spatial resolution and sensitivity to electrode movement and contact quality. EIT can be useful to applications, where there are conductive contrasts between tissues, fluids, or gasses, such as imaging of cancerous or ischemic tissue or functional monitoring of breathing, blood flow, gastric motility, and neural activity. The past decade has seen clinical application and commercial activity using EIT for ventilation monitoring. Interpretation of EIT-based measures is complex, and this review paper focuses on describing the image interpretation “pathway.” We review this pathway, from Tissue Electrical Properties, EIT Electrodes & Hardware, Sensitivity, Image Reconstruction, Image Processing to EIT Measures. The relationship is discussed between the clinically relevant parameters and the reconstructed properties. An overview is given of areas of EIT application and of our perspectives for research and development.
Autors: Andy Adler;Alistair Boyle;
Appeared in: IEEE Transactions on Biomedical Engineering
Publication date: Nov 2017, volume: 64, issue:11, pages: 2494 - 2504
Publisher: IEEE
 
» Electrical Properties Tomography Based on $B_{{1}}$ Maps in MRI: Principles, Applications, and Challenges
Abstract:
Objective: The purpose is to provide a comprehensive review of the electrical properties tomography (EPT) technique, which was introduced to image the electrical properties (EPs) of tissue noninvasively by exploiting the measured field data of MRI. Methods: We reviewed the principle of EPT, reconstruction methods, biomedical applications such as tumor imaging, and existing challenges. As a key application of EPT, the estimation of specific absorption rate (SAR) due to MRI was discussed in the background of elevated risk of tissue heating at high field. Results and Conclusion: Since the originally proposed local, homogeneous Helmholtz equation-based reconstruction algorithm, advanced EPT algorithms have emerged to address the challenges of EPT, including reconstruction error near tissue boundaries, noise sensitivity, inaccurate phase estimation, and elimination of the unmeasurable component, along with demonstrations of in vivo experiments. EPT techniques have been applied to investigate EPs of both healthy and pathological tissues in vivo and factors contributing to various EP value, including sodium, water content, etc. More studies are anticipated to consolidate the current findings. EPT-based subject-specific SAR estimation has led to in vivo demonstration of its feasibility and prediction of temperature increase of phantom during MRI scans merely using measured data. Significance: EPT has the advantage of high resolution and practical feasibility in a clinical setup for imaging the biomedically interesting EPs of tiss- e in the radiofrequency range. EPT-based SAR estimation is another promising topic for predicting tissue heating of individual subjects during a specific MRI scan.
Autors: Jiaen Liu;Yicun Wang;Ulrich Katscher;Bin He;
Appeared in: IEEE Transactions on Biomedical Engineering
Publication date: Nov 2017, volume: 64, issue:11, pages: 2515 - 2530
Publisher: IEEE
 
» Electrical–Thermal Characterization of Through Packaging Vias in Glass Interposer
Abstract:
Low-cost thin glass is developed as a promising material to advanced interposers for high density electrical interconnection in 2.5-D and three-dimensional (3-D) integration. In this paper, the electrical–thermal performance of through glass vias is investigated. The distributed transmission lines model for tapered through glass vias (T-TGVs) in signal-ground-signal type differential structure is first established and validated against the 3-D full-wave electromagnetic simulator. The model is applicable to TGVs made of carbon nanotubes(CNTs) by incorporating CNT quantum and kinetic effects. Using the proposed model, the impact of various parameters on the electrical characteristics of the differential T-TGVs is investigated. It is observed that the inductive element of conductor loss plays a significant role on the electrical performance, which makes the CNT-TGV interconnects show unique electrical characterization that totally different from its through silicon vias (TSVs) counterpart. For example, the signal loss of TGV interconnects in different-mode signaling is even lower than that in common-mode and increasing via pitch increases signal loss. Furthermore, the thermal performance of 2.5-D integration with TGVs is investigated with COMSOL multiphysics. It is shown that TGV is a primary path for heat dissipation and increasing TGV distribution density can significantly lower the peak temperature of 2.5-D integration. Because of high thermal conductivity of CNTs, glass interposer with CNT-TGVs can achieve better thermal performance in comparison to its Cu counterpart.
Autors: Libo Qian;Yinshui Xia;Ge Shi;Jiang Wang;Yidie Ye;Shimin Du;
Appeared in: IEEE Transactions on Nanotechnology
Publication date: Nov 2017, volume: 16, issue:6, pages: 901 - 908
Publisher: IEEE
 
» Electrically “Long” Dipoles in a Collocated/Orthogonal Triad—for Direction Finding and Polarization Estimation
Abstract:
In dipole-antenna array signal-processing algorithm development, research has focused on “short dipoles” whose physical length () is under (1/10) of a wavelength . Such electrically “short” dipoles have very small input impedances, rendering such “short” dipoles to be inefficient radiators. Practical dipoles, with an electrical length of , have notably larger input impedance, hence making them better radiators. Of such practical dipoles, this paper investigates their use for azimuth-polar direction finding and for polarization estimation. This paper will first present the measurement model (i.e., array manifold) of a triad of such practical dipoles, collocated in space and orthogonally oriented. This paper will then develop the corresponding closed-form algorithms to estimate the bivariate azimuth–elevation direction-of-arrival or the bivariate polarization. Such closed-form algorithms previously have been unavailable in the existing literature for such a triad of electrically “long” dipoles of pragmatic radiation efficiency.
Autors: Kainam Thomas Wong;Yang Song;Caleb J. Fulton;Salman Khan;Wai-Yip Tam;
Appeared in: IEEE Transactions on Antennas and Propagation
Publication date: Nov 2017, volume: 65, issue:11, pages: 6057 - 6067
Publisher: IEEE
 
» Electricity Markets and Renewables: A Survey of Potential Design Changes and Their Consequences
Abstract:
The design of wholesale electricity markets is complex. Unlike other commodities, electricity cannot be stored in a warehouse. Electricity generation must occur simultaneously with consumption, whereby electricity delivery is based on laws of physics. Under the structure of regulated electricity rates, consumers are generally not directly exposed to the instantaneous cost of the delivered electricity. Countries around the world have successfully managed these complexities by restructuring the electricity sector with markets that allow wholesale electricity suppliers to compete in providing energy, reliability services, financial services, and sometimes capacity. Still, wholesale electricity market restructuring has certainly been a moving target.
Autors: Erik Ela;Congcong Wang;Sai Moorty;Kenneth Ragsdale;Jon O'Sullivan;Mark Rothleder;Ben Hobbs;
Appeared in: IEEE Power and Energy Magazine
Publication date: Nov 2017, volume: 15, issue:6, pages: 70 - 82
Publisher: IEEE
 
» Electromagnetic Analysis of a Synchronous Reluctance Motor With Single-Tooth Windings
Abstract:
This paper explores some of the key electromagnetic design aspects of a synchronous reluctance motor that is equipped with single-tooth windings (i.e., fractional slot concentrated windings). The analyzed machine, a 6-slot 4-pole motor, utilizes a segmented stator core structure for ease of coil winding, pre-assembly, and facilitation of high slot fill factors (~60%). The impact on the motors torque producing capability and its power factor of these inter-segment air gaps between the stator segments is investigated through 2-D finite element analysis (FEA) studies where it is shown that they have a low impact. From previous studies, torque ripple is a known issue with this particular slot–pole combination of synchronous reluctance motor, and the use of two different commercially available semi-magnetic slot wedges is investigated as a method to improve torque quality. An analytical analysis of continuous rotor skewing is also investigated as an attempt to reduce the torque ripple. Finally, it is shown that through a combination of 2-D and 3-D FEA studies in conjunction with experimentally derived results on a prototype machine that axial fringing effects cannot be ignored when predicting the q-axis reactance in such machines. A comparison of measured orthogonal axis flux linkages/reactances with 3-D FEA studies is presented for the first time.
Autors: C. M. Donaghy-Spargo;B. C. Mecrow;J. D. Widmer;
Appeared in: IEEE Transactions on Magnetics
Publication date: Nov 2017, volume: 53, issue:11, pages: 1 - 7
Publisher: IEEE
 
» Electromagnetic Design and Analysis of a Novel Transmission System Supporting Multi-Path Power Flows for Electric Vehicles
Abstract:
This paper proposes a novel transmission system supporting multi-path power flows for electric vehicles (EVs). It mainly consists of a coaxial magnetic gear (CMG), a lock, a clutch, and two electric machines (EMs). The key feature of the CMG is that its modulating ring can rotate freely. One of the EMs is integrated with the CMG, which constitutes an integrated magnetic gear permanent magnet machine. And the other is connected to the inner rotor of the CMG through a clutch and a shaft with a lock. By toggling the clutch, controlling the states of the lock and the two EMs, the proposed transmission system can achieve flexible power splits. It is very interesting that one of the EM can play the role of a flywheel storage device when necessary, which is capable of buffering the energy from regenerative braking, so as to protect the battery. In this paper, the configuration of the transmission system is illustrated; its operating principle is elaborated. Then, the electromagnetic design is conducted to meet the demands arising from EVs. Finally, the electromagnetic performances are analyzed by using finite-element method, which verifies the rationality of the electromagnetic design.
Autors: Yujun Shi;Linni Jian;Jin Wei;Zhengxing Deng;Zhijian Ling;
Appeared in: IEEE Transactions on Magnetics
Publication date: Nov 2017, volume: 53, issue:11, pages: 1 - 7
Publisher: IEEE
 
» Electromagnetic Scattering From Individual Crumpled Graphene Flakes: A Characteristic Modes Approach
Abstract:
Graphene flakes (GFs) in real composites are rarely perfectly flat, and often exhibit complicated crumpled shapes. Therefore, the goal of this paper was to quantify the electromagnetic scattering characteristics of individual crumpled GFs with shapes resembling those found in real composites. The extinction cross sections of tens of GFs, with different sizes and various levels of crumpleness, were calculated using multiple independent solvers. The results show that resonances in the extinction cross section spectrum decrease in amplitude as the GFs become more crumpled. Moreover, some crumpled GFs exhibited a broader resonance than that of perfectly flat GFs. To explain these results, we used a characteristic mode analysis to decompose the graphene surface currents into a set of fundamental currents or modes. For perfectly flat square GFs, the vertical and horizontal modes were found to overlap and resonate at the same frequencies. However, as the GFs became more crumpled, the horizontal/vertical symmetry broke down causing the corresponding modes to separate and resonate at different frequencies leading to an overall broader bandwidth. These results attest to the importance of modeling the exact shape of GFs to accurately characterize their electromagnetic response.
Autors: Kalyan C. Durbhakula;Ahmed M. Hassan;Fernando Vargas-Lara;Deb Chatterjee;Md. Gaffar;Jack F. Douglas;Edward J. Garboczi;
Appeared in: IEEE Transactions on Antennas and Propagation
Publication date: Nov 2017, volume: 65, issue:11, pages: 6035 - 6047
Publisher: IEEE
 
» Electromagnetic Torque Performance Analysis of a Parallel Hybrid Excitation Machine With Axial Paralleling of Permanent Magnet Part and Variable Reluctance Part
Abstract:
In this paper, the electromagnetic torque (EM) performance analysis of a parallel hybrid excitation machine (PHEM) is investigated. It is composed of a permanent magnet (PM) part and variable reluctance part. The flux paths of the two parts are independent and the armature windings are connected in series. PHEM is an axial parallel coupling of two different types of brushless machine. The mechanisms of EM torque for the two parts are quite different and many problems of torque coupling still remain unsolved. A 2-D EM-circuit coupling simulation model is built to analyze the torque characteristics and coupling relationships. The simulation results indicate that the PM part plays a main role in the output torque of PHEM. The large inductance ripple of variable reluctance part would cause large torque ripple in PHEM. The target machine is experimentally tested to verify the output torque characteristics. Furthermore, the torque-angle characteristics are studied with different field current and it shows that the best load angle could be around 110° to get maximum output torque and relatively smaller torque ripple.
Autors: Zhou Miao;Zhuoran Zhang;Weiwei Geng;Ye Liu;
Appeared in: IEEE Transactions on Magnetics
Publication date: Nov 2017, volume: 53, issue:11, pages: 1 - 4
Publisher: IEEE
 
» Electromagnetic–Mechanical Design of Synchronous Reluctance Rotors With Fine Features
Abstract:
This paper explores the tradeoff between the electromagnetic and mechanical performances with regard to the design of a synchronous reluctance machine rotor with fine features in the lamination profile—the analyzed machine consists of four rotor poles and its stator is equipped with single tooth coils. The change in the electromagnetic characteristics of the - and -axis reactances is explored for variation in radial and tangential rib widths and the impact of increased rib width on the saliency ratio of the machine. It is shown that the increased radial and tangential rib widths impair electromagnetic performance, with the tangential rib having the most pronounced effect on performance in this rotor design. The mechanical performance of the design is also explored in a similar manner, where it is shown that the high stress concentration in the rotor radial and tangential ribs limits the maximum speed of the machine in the field weakening region. The radial rib is found to have the dominant impact on supporting the flux guides. It is shown that the prototyped machine can achieve good electromagnetic performance while maintaining mechanical integrity up to a 25% overspeed of 10 000 r/min with features as small as 0.3 mm. Additionally, the challenges associated with manufacturing, selecting a higher rotor pole number, and the possibility of mechanical failure are also discussed in the context of electromagnetic–mechanical design of such rotors, with important avenues of further research suggested.
Autors: Christopher M Donaghy-Spargo;
Appeared in: IEEE Transactions on Magnetics
Publication date: Nov 2017, volume: 53, issue:11, pages: 1 - 8
Publisher: IEEE
 
» Electron Cyclotron Resonance Gain in the Presence of Collisions
Abstract:
A cyclotron resonance maser source using low-effective-mass conduction electrons in graphene, if successful, would allow for generation of far infrared (FIR) and terahertz (THz) radiation without requiring magnetic fields running into the tens of tesla. In order to investigate this possibility, we consider a situation in which electrons are effectively injected via pumping from the valence band to the conduction band using an IR laser source, subsequently gyrate in a magnetic field applied perpendicular to the plane of the graphene, and give rise to gain for an FIR/THz wave crossing the plane of the graphene. The treatment is classical, and includes on equal footing the electron interaction with the radiation field and the decay in electron energy due to collisional processes. Gain is found even though there is no inversion of the energy distribution function. Gain can occur for electron damping times as short as hundreds of femtoseconds.
Autors: Nightvid Cole;Thomas M. Antonsen;
Appeared in: IEEE Transactions on Plasma Science
Publication date: Nov 2017, volume: 45, issue:11, pages: 2945 - 2954
Publisher: IEEE
 
» Electronic–Photonic Co-Optimization of High-Speed Silicon Photonic Transmitters
Abstract:
System-level driven electronic–photonic codesign is the key to improving the bandwidth density and energy efficiency for high-speed silicon photonic links. In many data-communication scenarios, optical link power is dominated by its transmitter side including the laser source. In this paper, we propose a comprehensive co-optimization framework for high-speed silicon photonic transmitters utilizing compact models and a detailed optical simulation framework. Given technology and link constraints, microring and Mach–Zehnder transmitter designs are optimized and compared based on a unified optical phase shifter model. NRZ and PAM4 modulation schemes are analyzed and compared for microring-based transmitters at 50 Gb/s. Multistage and traveling wave Mach–Zehnder transmitters are optimized and discussed as well. The results show that, for a 50 Gb/s NRZ optical link, an optimized microring transmitter could save more than 60% of the total laser and driver power compared to an optimized Mach–Zehnder transmitter under equivalent photonic technology constraints. For a given datarate and receiver sensitivity, design tradeoffs of silicon photonic processes, devices, and architecture choices are discussed in depth. In addition, this paper introduces a new Simulink toolbox for transient optical simulation. Combined with the proposed optimization engine, it provides an electrooptical co-optimization approach toward truly energy-efficient high-speed silicon photonic links.
Autors: Sen Lin;Sajjad Moazeni;Krishna T. Settaluri;Vladimir Stojanović;
Appeared in: Journal of Lightwave Technology
Publication date: Nov 2017, volume: 35, issue:21, pages: 4766 - 4780
Publisher: IEEE
 
» Electroplated Co–Pt Thick-Film Magnets Prepared in Citric-Acid-Based Plating Baths
Abstract:
We electroplated Co–Pt thick films in acid plating baths using a citric acid, and evaluated the magnetic properties of the annealed films. The maximum coercivity value depended on the amount of the citric acid in the bath, and the high coercivity of approximately 800 kA/m was obtained around Co content of 43 at% for the bath with 30 g/L of citric acid. The thickness linearly increased with the increasing plating time, and high plating rate of approximately /min was obtained. Consequently, -thick films were realized keeping at high coercivity.
Autors: T. Yanai;R. Hamamura;J. Honda;A. Tomita;H. Yamada;N. Fujita;K. Takashima;M. Nakano;H. Fukunaga;
Appeared in: IEEE Transactions on Magnetics
Publication date: Nov 2017, volume: 53, issue:11, pages: 1 - 3
Publisher: IEEE
 
» Electrothermal Transient Analysis of GaN Power Amplifier With Dynamic Drain Voltage Biasing
Abstract:
AM-AM distortion due to dynamic drain voltage biasing for a power amplifier (PA) has been precisely emulated by an electrothermal transient analysis. A transistor model of a 20-W gallium nitride field-effect transistor (FET) in the PA for the electrothermal simulation is composed of thermal equivalent circuits and the Angelov FET model. Radio frequency performances of the PA were simulated by the transient analysis of amplitude modulation input signals with modulation frequencies from 2.5 to 10 MHz. The simulation results showed that a temperature variation in the PA caused AM-AM hysteresis on the order of MHz, which was consistent with the results obtained from a theoretical analysis of the transient temperature.
Autors: Shigeru Hiura;Ryo Ishikawa;
Appeared in: IEEE Microwave and Wireless Components Letters
Publication date: Nov 2017, volume: 27, issue:11, pages: 1019 - 1021
Publisher: IEEE
 
» Elman Neural Network-Based Identification of Krasnosel’skii–Pokrovskii Model for Magnetic Shape Memory Alloys Actuator
Abstract:
Magnetic shape memory alloys (MSMAs), which are a class of innovative functional materials, are used as the actuators to be applied widely in high-precision positioning. However, the hysteresis nonlinearity in the MSMA seriously affects the precision positioning of the MSMA-based actuator. In this paper, to study the hysteresis nonlinearity in the MSMA, the Krasnosel’skii–Pokrovskii (KP) model is employed to describe the hysteresis nonlinearity in the MSMA-based actuator, and the density function of the KP model is identified by the Elman neural network. The simulations show that the modeling error rate of the KP model using the Elman neural network is 0.81%, which is reduced by 63.5% compared with that of the KP model based on a recursive least-squares method. This result demonstrates that the KP model based on the Elman neural network can accurately describe the hysteresis nonlinearity in the MSMA-based actuator.
Autors: Rui Xu;Miaolei Zhou;
Appeared in: IEEE Transactions on Magnetics
Publication date: Nov 2017, volume: 53, issue:11, pages: 1 - 4
Publisher: IEEE
 
» Embedding Learning with Events in Heterogeneous Information Networks
Abstract:
In real-world applications, objects of multiple types are interconnected, forming Heterogeneous Information Networks. In such heterogeneous information networks, we make the key observation that many interactions happen due to some event and the objects in each event form a complete semantic unit. By taking advantage of such a property, we propose a generic framework called HyperEdge- BasedEmbedding (Hebe) to learn object embeddings with events in heterogeneous information networks, where a hyperedge encompasses the objects participating in one event. The Hebe framework models the proximity among objects in each event with two methods: (1) predicting a target object given other participating objects in the event, and (2) predicting if the event can be observed given all the participating objects. Since each hyperedge encapsulates more information of a given event, Hebe is robust to data sparseness and noise. In addition, Hebe is scalable when the data size spirals. Extensive experiments on large-scale real-world datasets show the efficacy and robustness of the proposed framework.
Autors: Huan Gui;Jialu Liu;Fangbo Tao;Meng Jiang;Brandon Norick;Lance Kaplan;Jiawei Han;
Appeared in: IEEE Transactions on Knowledge and Data Engineering
Publication date: Nov 2017, volume: 29, issue:11, pages: 2428 - 2441
Publisher: IEEE
 
» Emittance Growth in the DARHT-II Linear Induction Accelerator
Abstract:
The dual-axis radiographic hydrodynamic test (DARHT) facility uses bremsstrahlung radiation source spots produced by the focused electron beams from two linear induction accelerators (LIAs) to radiograph large hydrodynamic experiments driven by high explosives. Radiographic resolution is determined by the size of the source spot, and beam emittance is the ultimate limitation to spot size. On the DARHT-II LIA, we measure an emittance higher than predicted by theoretical simulations, and even though this accelerator produces submillimeter source spots, we are exploring ways to improve the emittance. Some of the possible causes for the discrepancy have been investigated using particle-in-cell codes. The simulations establish that the most likely source of emittance growth is a mismatch of the beam to the magnetic transport, which can cause beam halo.
Autors: Carl Ekdahl;Carl A. Carlson;Daniel K. Frayer;B. Trent McCuistian;Christopher B. Mostrom;Martin E. Schulze;Carsten H. Thoma;
Appeared in: IEEE Transactions on Plasma Science
Publication date: Nov 2017, volume: 45, issue:11, pages: 2962 - 2973
Publisher: IEEE
 
» End of Second Term as Editor-in-Chief [Editor's Remarks]
Abstract:
Presents the introductory editorial for this issue of the publication.
Autors: Hisao Ishibuchi;
Appeared in: IEEE Computational Intelligence Magazine
Publication date: Nov 2017, volume: 12, issue:4, pages: 3 - 3
Publisher: IEEE
 
» Energization-Status Identification of Three-Phase Three-Core Shielded Distribution Power Cables Based on Non-Destructive Magnetic Field Sensing
Abstract:
Three-phase three-core distribution power cables are widely deployed in power distribution networks and are continually being extended to address the ever-increasing power demand in modern metropolises. Unfortunately, there are high risks for the repair crew to operate on energized distribution power cables, which can cause deadly consequences such as electrocution and explosion. The predominant energization-status identification techniques used today are either destructive or only applicable to un-shielded power cables. Moreover, the background interferences affect the sensing technique reliability. In this paper, we have developed a non-destructive energization-status identification technique to identify energized three-phase three-core distribution power cables by measuring magnetic fields around the cable surface. The analysis shows that the magnetic-field-distribution pattern as a function of azimuth around the cable surface of the energized (current- or voltage-energized) three-phase three-core distribution power cable is distinguishable from the de-energized one. The non-idealities of phase currents and cable geometry were also discussed, and the proposed method still works under these circumstances. The sensing platform for implementing this technique was developed accordingly, consisting of magnetoresistive sensors, a triple-layered magnetic shielding, and a data acquisition system. The technique was demonstrated on a 22-kV three-phase three-core distribution power cable, and the energized status of the cable can be successfully identified. The proposed technique does not damage cable integrity by piercing the cable, or exposing the repair crew to hazardous high-voltage conductors. The platform is easy to operate and it can significantly improve the situational awareness for the repair crew, and enhance the stability of power distribution networks.
Autors: Ke Zhu;Wing Kin Lee;Philip W. T. Pong;
Appeared in: IEEE Sensors Journal
Publication date: Nov 2017, volume: 17, issue:22, pages: 7405 - 7417
Publisher: IEEE
 
» Energy Autonomous Wireless Valve Leakage Monitoring System With Acoustic Emission Sensor
Abstract:
Industrial internet will improve process control and increase efficiency to maximize industrial output. Key enabling technologies include low-power wireless communication, energy harvesting power autonomous devices along with the latest in sensing devices. This paper presents a wireless sensing system developed for the key industrial application of condition monitoring, specifically; valve leakage detection. The system integrates advances in all of the three aforementioned topics. A novel MEMS-based acoustic emission sensor is described to detect valve leakage manifested as vibrations in certain frequency bands. An in-house developed ultra-low power wake up radio technology, which enables the deployment of this sensor, will be presented. Two energy-harvesting systems: thermal harvesting in the sensor node and an industrial current loop harvester for the base station are developed. Integration and piloting of this system is described and evaluation results presented. The system presented offers a repeatable and adaptable sensor system deployed for valve leakage detection in an ATEX industrial environment.
Autors: Colm Mc Caffrey;Teuvo Sillanpää;Henrik Huovila;Joona Nikunen;Sami Hakulinen;Pekka Pursula;
Appeared in: IEEE Transactions on Circuits and Systems I: Regular Papers
Publication date: Nov 2017, volume: 64, issue:11, pages: 2884 - 2893
Publisher: IEEE
 
» Energy Detection With Random Arrival and Departure of Primary Signals: New Detector and Performance Analysis
Abstract:
By taking into account the random arrival and departure of primary signals, spectrum sensing is formulated to a hypothesis testing problem with null hypothesis : primary signals are absent or present but departing within a sensing interval (secondary users are allowed to access the spectrum), and alternative hypothesis : primary signals are present and not departing within a sensing interval (secondary users are not allowed to access the spectrum). The above-mentioned binary hypothesis testing involves two mutually exclusive random variables (i.e., the departure and arrival time instants of primary signals). To tackle these random variables, we develop an average log-LRT (aveLLR) based energy detector (ED) by using the Bayesian criterion. The theoretical performance of the aveLLR-based ED is analyzed and numerical simulations are provided to demonstrate its superior performance. It is interesting that when the ratio of the length of sensing intervals to the holding time of channel states is small, the proposed aveLLR-based ED is approximately reduced to the conventional ED (C-ED). It was commonly believed that high primary user traffic would degrade the performance of C-ED severely, as C-ED does not consider the random arrival and departure of primary signals. However, we reveal that the ratio plays a key role, and when the ratio is small, the impact of the primary user traffic on the C-ED is marginal.
Autors: Ming Jin;Qinghua Guo;Youming Li;Jiangtao Xi;Yanguang Yu;
Appeared in: IEEE Transactions on Vehicular Technology
Publication date: Nov 2017, volume: 66, issue:11, pages: 10092 - 10101
Publisher: IEEE
 
» Energy Efficiency and Spectrum Efficiency Tradeoff in the D2D-Enabled HetNet
Abstract:
We investigate the tradeoff between energy efficiency (EE) and spectrum efficiency (SE) in the heterogeneous network composed of a macro base station (BS), several pico BSs, and device-to-device (D2D) communication pairs during the uplink transmission. A utility function of the tradeoff between EE and SE is defined first. Then, we formulate the tradeoff utility maximization problem as a joint channel allocation and power control problem for cellular and D2D users. The original problem is transformed into a more tractable subtractive form, and we further decompose the problem into several subproblems that can be solved separately. Numerical results confirm the effectiveness of the proposed scheme and offer valuable insights. Compared with EE, SE is much less sensitive to the variation of the tradeoff factor, which indicates that our proposed scheme can achieve high EE while guaranteeing a fairly large value of SE with a properly chosen EE–SE tradeoff factor.
Autors: Hui Gao;Min Wang;Tiejun Lv;
Appeared in: IEEE Transactions on Vehicular Technology
Publication date: Nov 2017, volume: 66, issue:11, pages: 10583 - 10587
Publisher: IEEE
 
» Energy Efficiency Evaluation of Multi-Tier Cellular Uplink Transmission Under Maximum Power Constraint
Abstract:
This paper evaluates the energy efficiency of uplink transmission in heterogeneous cellular networks (HetNets), where fractional power control (FPC) is applied at user equipments (UEs) subject to a maximum transmit power constraint. We first consider an arbitrary deterministic HetNet and characterize the properties of energy efficiency for UEs in different path loss regimes, or different access regions. By introducing the notion of transfer path loss, we reveal that, for UE whose path loss is below the transfer path loss, its energy efficiency highly depends on the value of power control coefficient adopted by FPC. In contrast, for UE with path loss above the transfer path loss, the uplink energy efficiency asymptotically decreases inversely with path loss, independent of the adopted power control coefficient. Based on these properties, we characterize the optimal power control coefficients for maximizing the energy efficiency of FPC in different access regions. Next, we extend the analysis to stochastic HetNets where UEs and BSs are distributed as independent Poisson point processes, and investigate the distribution of transmit power for uplink UEs. Moreover, the probability of truncation outage due to constrained maximal transmit power, as well as the average energy efficiency of UEs are analytically derived as functions of the BS and UE densities, power control coefficient, and receiver threshold. Simulation results validate the analytical results, show the consistency between deterministic and stochastic analyses, and suggest suitable power control coefficient for achieving energy efficient uplink transmission by FPC in HetNets.
Autors: Jing Zhang;Lin Xiang;Derrick Wing Kwan Ng;Minho Jo;Min Chen;
Appeared in: IEEE Transactions on Wireless Communications
Publication date: Nov 2017, volume: 16, issue:11, pages: 7092 - 7107
Publisher: IEEE
 
» Energy Efficient Beamforming for Massive MIMO Public Channel
Abstract:
For massive MIMO public channel with any sector size in either microwave or millimeter wave (mmwave) band, this paper studies the beamforming design to minimize the transmit power while guaranteeing the quality of service for randomly deployed users. First the ideal beampattern is derived via Parseval Identity, based on which a beamforming design problem is formulated to minimize the gap with the idea beampattern. The problem is transformable to a multiconvex one and an iterative optimization algorithm is used to obtain the full-digital beamformer. In addition, with the help of same beampattern theorem, the power amplifier efficiency of the beamformer is improved with unchanged beampattern. Finally, the practical hybrid implementation is obtained that achieves the full-digital beamformer solution. Simulations verify the advantages of the proposed scheme over existing ones.
Autors: Cheng Zhang;Yongming Huang;Yindi Jing;Luxi Yang;
Appeared in: IEEE Transactions on Vehicular Technology
Publication date: Nov 2017, volume: 66, issue:11, pages: 10595 - 10600
Publisher: IEEE
 
» Energy Investment Planning at a Private Company: A Mathematical Programming-Based Model and Its Application in Turkey
Abstract:
We consider a mid-sized private electricity generating company that plans to enter the market that is partially regulated. There is a cap and trade system in operation in the industry. There are nine possible power plant types that the company considers to invest on through a planning horizon. Some of these plants may include a carbon capture and storage technology. We develop a stochastic mixed-integer linear program for this problem where the objective is to maximize the expected net present value of the profit obtained. We include restrictions on the maximum and minimum possible amount of investment for every type of investment option. We also enforce market share conditions such that the percentage of the total investments of the company over the total installed capacity of the country stay between upper and lower bounds. Moreover, in order to distribute the investment risk, the percentage of each type of power plant investment is restricted by some upper bound. We tested the model for a hypothetical company operating in Turkey. The results show that the model is suitable to be used for determining the investment strategy of the company.
Autors: Semra Ağralı;Fulya Terzi;Ethem Çanakoğlu;Esra Adıyeke;Yıldız Arıkan;
Appeared in: IEEE Transactions on Power Systems
Publication date: Nov 2017, volume: 32, issue:6, pages: 4180 - 4187
Publisher: IEEE
 
» Energy Management in Hybrid Energy Large-Scale MIMO Systems
Abstract:
This paper investigates the energy consumption of distributed large-scale MIMO systems made up of a set of remote radio heads (RRHs), each of which is powered by both an independent energy harvesting source and the grid. The grid energy source allows to compensate for the randomness and intermittency of the harvested energy. Hence, the problem of grid power consumption minimization has to be solved by efficiently managing the energy delivered from different sources while satisfying the system requirements in terms of users’ quality of service demands. First, this paper solves the optimal offline version of the problem using linear programming. In fact, the main problem is decomposed and heuristically solved in order to deal with the large number of constraints and variables. Since sometimes all the users cannot be served, an iterative link removal algorithm is devised ensuring the feasibility of the problem. Next, we investigate the online energy management problem. We first propose a dynamic programming approach to obtain the optimal online solution but with high complexity. Then, we develop and propose a low complexity heuristic solution based on using the maximal available energy at the batteries. Taking benefits of the characteristics of large-scale MIMO and the modeling of the harvested energy as Markov chains, we devise an efficient online energy management algorithm based on energy prediction. Finally, we propose a heuristic solution for RRH on/off operation with the objective of improving the system energy efficiency. The performance of the proposed algorithms is evaluated by simulations and it is shown that the proposed energy management approaches offer efficient use of nonrenewable energy to compensate the variability of renewable energy in large-scale MIMO systems.
Autors: Rami Hamdi;Elmahdi Driouch;Wessam Ajib;
Appeared in: IEEE Transactions on Vehicular Technology
Publication date: Nov 2017, volume: 66, issue:11, pages: 10183 - 10193
Publisher: IEEE
 
» Energy Storage and Power Electronics Technologies: A Strong Combination to Empower the Transformation to the Smart Grid
Abstract:
The electric power industry is facing unprecedented transformations and challenges with the implementation of the smart grids. This new grid paradigm has arisen to build a flexible electric power system that better coordinates energy resources and loads aiming at efficiently delivering sustainable, economic and secure electricity supplies. As a part of the smart grids (SGs), microgrids (MGs) have been developed to exploit the full benefits from the integration of distributed energy resources, especially distributed renewable generation based on variable and intermittent sources, such as wind and solar. Nevertheless, meeting all these goal requires the implementation of innovative energy storage technologies integrated with high efficiency and very fast response electronic power conditioning systems to interface with the electrical grid. Power electronics systems play a key role in regulating the raw energy from energy storage systems (ESSs) and connecting to the electrical grid. Hence, this paper performs a comprehensive analysis of major technologies in electrical energy storage systems and their electronic interface for applications in smart grids. The work provides a complete study of the technology profile of both energy storage and power electronics suitable for applications in the evolving grid.
Autors: Marcelo G. Molina;
Appeared in: Proceedings of the IEEE
Publication date: Nov 2017, volume: 105, issue:11, pages: 2191 - 2219
Publisher: IEEE
 
» Energy-Efficient Computing With Probabilistic Magnetic Bits—Performance Modeling and Comparison Against Probabilistic CMOS Logic
Abstract:
This paper focuses on the design, performance modeling, and evaluation of probabilistic logic using superparamagnetic nanomagnets for which there exists a strong interplay between deterministic dynamics and intrinsic thermal noise. The switching element in the spin domain is chosen as the giant spin-Hall effect (GSHE) device that operates based on the dipolar coupling phenomenon in a two-magnet system to achieve low-energy ( fJ/b) and low-power ( W) switching characteristics. The use of spin currents on the order of a few tens of mA/m2 in the subcritical regime to operate the GSHE device yields nondeterministic switching behavior with probability of correctness less than 100%. Therefore, the proposed technique allows us to trade off circuit accuracy for tremendous reduction in energy and power dissipation. In this paper, we identify the required dimensions and material parameters of the read–write units to ensure robust magnetic dipolar coupling for reliable operation of the GSHE switch. Then, through Monte Carlo simulations, we evaluate the probabilistic switching behavior of the GSHE switch as a function of the input spin current amplitude and pulsewidth for various orientations of the magnetization vectors. The delay of the GSHE switch is quantified using a probability distribution function owing to the randomness imparted to the dynamics by intrinsic thermal noise of the nanomagnets. The relationship between the probability of correctness and the energy dissipation of the GSHE switch is quantified. The results are extended to evaluate the performance and circuit error rate of complex logic gates, such as NAND and NOR, constructed using the GSHE switch. It is s- own that unlike the probabilistic CMOS (PCMOS) logic, the circuit error rate in the GSHE logic becomes a function of the input vector combination and the prior state of the switch. These nuances are captured in the compact model of the circuit error rate of multiple-input GSHE logic developed in this paper. The performance of the probabilistic GSHE logic is compared with that of PCMOS logic at the 14 nm technology node. Since the noise generation process in PCMOS logic has a limited bandwidth of tens of megahertz and consumes tens of microwatt power, the peripheral circuitry becomes prohibitive. By utilizing the inherent thermal stochasticity, nanomagnets provide a clear advantage to implement probabilistic computing platform targeted toward error-tolerant applications such as those from the image processing and machine learning domains.
Autors: Nikhil Rangarajan;Arun Parthasarathy;Nickvash Kani;Shaloo Rakheja;
Appeared in: IEEE Transactions on Magnetics
Publication date: Nov 2017, volume: 53, issue:11, pages: 1 - 10
Publisher: IEEE
 
» Energy-Efficient Design of Processing Element for Convolutional Neural Network
Abstract:
Convolutional neural network (CNN) is the most prominent algorithm for its wide usage and good performance. Despite the fact that the processing element (PE) plays an important role in CNN processing, there has been no study focusing on PE design optimized for state-of-the-art CNN algorithms. In this brief, we propose an optimal PE implementation including a data representation scheme, circuit block configurations, and control signals for energy-efficient CNN. To validate the excellence of this brief, we compared our proposed design with several previous methods, and fabricated a silicon chip. The software simulation results demonstrated that we can reduce 54% of data bit lengths with negligible accuracy loss. Our optimization on PE achieves to save computing power up to 47%, and an accelerator exploiting our method shows superior results in terms of power, area, and external DRAM access.
Autors: Yeongjae Choi;Dongmyung Bae;Jaehyeong Sim;Seungkyu Choi;Minhye Kim;Lee-Sup Kim;
Appeared in: IEEE Transactions on Circuits and Systems II: Express Briefs
Publication date: Nov 2017, volume: 64, issue:11, pages: 1332 - 1336
Publisher: IEEE
 
» Energy-Efficient Localization Game for Wireless Sensor Networks
Abstract:
We study the energy saving problem of nodes for the hybrid directions of arrival/received signal strength (DoA/RSS) localization scheme in wireless sensor networks. To solve this problem, both the transmission power and the sleep times of the anchor nodes are allocated while the target is required to be localized with a pre-specified accuracy. We use the leader–follower Stackelberg game to model our problem, in which, the target is the follower and the set of the target’s neighbor anchor nodes, named coalition of anchor nodes (CANs), is the leader. We prove the existence and uniqueness of the Stackelberg equilibrium (SE) by giving closed-form expressions for the SE strategies of both the target and the CANs. The superior performance of the proposed scheme is validated through simulations.
Autors: ThiOanh Bui;Pingping Xu;Wenxiang Zhu;Guilu Wu;Nanlan Jiang;
Appeared in: IEEE Communications Letters
Publication date: Nov 2017, volume: 21, issue:11, pages: 2468 - 2471
Publisher: IEEE
 
» Energy-Efficient Train Control by Multi-Train Dynamic Cooperation
Abstract:
Regenerative braking technology has been widely used by subway trains, where regenerative braking energy (RBE) will be generated during train braking processes. An RBE usage method is proposed for subway trains, where train braking processes are predicted based on the field data of the train control system, and the braking information will be obtained in advance. The RBE will be calculated, and then, part or all of it will be distributed to neighboring trains in the same or adjacent power supply sections. Several feasible schemes for the RBE distribution are given, where the speed profiles of the neighboring trains will be adjusted to absorb the distributed RBE. An optimal RBE distribution scheme with the most effective usage of RBE will be obtained based on calculation results of the given schemes. For each adjusted speed profile of the neighboring train, a power process will be normally introduced. Existence of the optimal solution for speed profile adjustment is analyzed under the precondition that the train runs in a long speed-holding journey, and then, the necessary condition of the optimal solution is found by perturbance analysis. A simulation case of Yizhuang Line in Beijing subway is studied, and the simulation results show that the proposed method can use the RBE efficiently.
Autors: Xubin Sun;Hong Lu;Hairong Dong;
Appeared in: IEEE Transactions on Intelligent Transportation Systems
Publication date: Nov 2017, volume: 18, issue:11, pages: 3114 - 3121
Publisher: IEEE
 
» Enhanced Anisotropy in Tetragonalized (Cu,Co)Fe2O4 Particles via the Jahn–Teller Effect of Cu2+ Ions
Abstract:
We studied the Jahn–Teller (JT) effect of Cu2+ ions on the tetragonalization of CuFe2O4 and (Cu,Co)Fe2O4 particles. Sub-micrometer-sized CuFe2O4 and (Cu,Co)Fe2O4 particles were synthesized via coprecipitation and flux methods, followed by a heat-treatment process. From the X-ray diffraction patterns, all particles were found to be cubic spinel after flux treatment. The tetragonalization process was carried out by a heat-treatment process in air, where the temperature was varied between 700 °C and 900 °C, followed by furnace cooling. We confirmed that the ideal temperature for the tetragonalization of both CuFe2O4 and (Cu,Co)Fe2O4 is 900 °C. The obtained single-phase tetragonal spinel-structured CuFe2O4 and (Cu,Co)Fe2O4 particles indicate tetragonal distortion as a consequence of the JT effect of the Cu2+ ions. The results of saturation magnetization suggest that most of the divalent ions are in the B sites. The lengthening of the c-axis due to the JT effect increased the coercivity of the CuFe2O4 and (Cu,Co)Fe2O4 particles during the cubic–tetragonal phase transformation. The tetragonal (Cu,Co)Fe2O4 particles showed a saturation magnetization of 26 emu/g and a coercivity of 2200 Oe.
Autors: Hawa Latiff;Mikio Kishimoto;Sonia Sharmin;Eiji Kita;Hideto Yanagihara;Takashi Nakagawa;
Appeared in: IEEE Transactions on Magnetics
Publication date: Nov 2017, volume: 53, issue:11, pages: 1 - 4
Publisher: IEEE
 
» Enhanced gm and fT With High Johnson’s Figure-of-Merit in Thin Barrier AlGaN/GaN HEMTs by TiN-Based Source Contact Ledge
Abstract:
A high combination of transconductance (), current gain cutoff frequency () and three terminal breakdown voltage was achieved using thin barrier AlGaN/GaN HEMTs and TiN-based source contact ledge. The sheet resistance is effectively reduced, whereas the peak extrinsic trans-conductance is improved by 24% from 334 to 415 mS/mm. The thin barrier AlGaN/GaN HEMTs with TiN-based source ledge exhibit a maximum drain current of 1096 mA/mm, a three-terminal off-state breakdown voltage (BV) of 151 V, a high current-gain cutoff frequency of 69 GHz, and a high power-gain cutoff frequency of 110 GHz. No significant drain current collapse was observed on thin barrier AlGaN/GaN HEMTs with TiN-based source contact ledge. The uniform characteristic over a wide range of bias condition is achieved by using the TiN-based source contact ledge devices. The calculated Johnson’s figures of merit (J-FOM = BV) is 10.4 THz-V, which is the highest record so far for T-gate SiN passivation AlGaN/GaN HEMTs without source field plate.
Autors: Ling Yang;Minhan Mi;Bin Hou;Hengshuang Zhang;Jiejie Zhu;Qing Zhu;Yang Lu;Meng Zhang;Yunlong He;Lixiang Chen;Xiaowei Zhou;Ling Lv;Xiaohua Ma;Yue Hao;
Appeared in: IEEE Electron Device Letters
Publication date: Nov 2017, volume: 38, issue:11, pages: 1563 - 1566
Publisher: IEEE
 
» Enhanced Magnetic Field Sensitivity in Magnetoelectric Composite Based on Positive Magnetostrictive/Negative Magnetostrictive/Piezoelectric Laminate Heterostructure
Abstract:
Resonance magnetoelectric (ME) responses are investigated for the ME laminate heterostructure consisting of positive magnetostrictive material FeCuNbSiB, negative magnetostrictive material Ni and piezoelectric material PZT-8. On one hand, both a built-in magnetic field induced by the strong magnetic interactions between positive magnetostrictive and negative magnetostrictive materials and an intrinsic anisotropic field with obvious hysteresis and remnant magnetization in Ni layer result in a large zero-biased ME effect. The corresponding zero-biased ME voltage coefficient reaches 10.12 V/Oe (126.5 V/cm Oe), which is about 3 times larger than that of traditional Ni/PZT-8 (NP) laminate. On the other hand, the additional stress produced by the high magnetic permeability FeCuNbSiB layer enhances the magnetostriction of Ni layer and ME response. The corresponding maximum ME voltage coefficient (dVME/dHac) is 12.09 V/Oe (150.87 V/cm Oe) at bias magnetic field Oe. It is further found that even a step change of ac magnetic field less than 10−10 T can be clearly distinguished by the proposed ME composite. The value of ME voltage sensitivity to dc magnetic fields (dVME/dH reaches ~76.7 mV/Oe at Oe and Oe. Correspondingly, the proposed laminate heterostructure is able to possess both strong ac and dc magnetic field sensitivities.
Autors: Lei Chen;Yao Wang;
Appeared in: IEEE Transactions on Magnetics
Publication date: Nov 2017, volume: 53, issue:11, pages: 1 - 5
Publisher: IEEE
 
» Enhanced Magnetic Properties of Spark Plasma Sintered (La/Ce)–Fe–B Magnets
Abstract:
La substitution for Ce inhibits the growth of the CeFe2 phase and promotes the formation of the single 2:14:1 phase, leading to an improvement in the magnetic properties of melt-spun (La/Ce)3Fe14B ribbons. Among which, the (La0.3Ce0.7)3Fe14B ribbon produced a high remanence of 6.86 kG, a coercivity of 5.51 kOe, and a maximum energy product (BH)max of 7.68 MGOe. After spark plasma sintering, the compacted (La0.3Ce0.7)3Fe14B magnet with good remanence and coercivity was successfully prepared, and these properties were enhanced to 5.14 kG and 5.60 kOe, respectively, leading to an energy product of 4.59 MGOe for the magnet with 5 wt % NdCu addition.
Autors: Q. M. Lu;J. Niu;W. Q. Liu;M. Yue;Z. Altounian;
Appeared in: IEEE Transactions on Magnetics
Publication date: Nov 2017, volume: 53, issue:11, pages: 1 - 3
Publisher: IEEE
 
» Enhanced Photocatalytic Activity of Core–Shell ZnFe2O4@ZnO Nanoparticles for Visible Light Photodegradation
Abstract:
A facile, efficient approach to fabricate ZnFe2O4@ZnO nanoparticles with a good core–shell structure was reported, involving the coating of successive layers of ZnO nanoparticles on a magnetic core by a sol–gel hydrothermal method at low temperatures. The as-synthesized ZnFe2O4@ZnO nanoparticles exhibited a narrow size distribution, with a typical size of 210 ± 19 nm and shell thickness of 35 nm. The ZnFe2O4@ZnO photocatalyst exhibited high photocatalytic activity for the degradation of methylene blue under solar light. Compared with ZnFe2O4, ZnFe2O4@ZnO exhibited higher photocatalytic efficiency, caused by the generation of a large number of electron–hole pairs. ZnFe2O4@ZnO exhibited excellent reusability with high photocatalytic efficiencies, indicative of its suitability for the solar photocatalytic applications.
Autors: Jun-Sik Nam;Ki Chang Nam;Kyong-Hoon Choi;Bong Joo Park;Jin-Seung Jung;
Appeared in: IEEE Transactions on Magnetics
Publication date: Nov 2017, volume: 53, issue:11, pages: 1 - 5
Publisher: IEEE
 
» Enhanced Target Detection for HFSWR by 2-D MUSIC Based on Sparse Recovery
Abstract:
This letter proposes using the 2-D multiple-signal classification (MUSIC) based on sparse recovery (SR) to improve the target-detection capability of high-frequency surface wave radar (HFSWR). Usually, for wide-beam HFSWRs, target detection is first conducted in the range-Doppler spectrum, and bearings are then estimated by superresolution methods such as MUSIC. Unfortunately, the conventional cascaded method can easily result in unfavorable deterioration of multitarget detection when different target signals tend to become mixed in the Doppler spectrum. Moreover, sea clutter is an unwanted signal that frequently masks target signals. To enhance the detection of multiple targets and targets embedded in sea clutter, spatial–temporal joint estimation has been proposed. However, because of the lack of spatial–temporal snapshots caused by the nonstationarity of target signals, the efficiency of the estimator cannot be guaranteed. To overcome this shortcoming, multiple-measurement-vector-based SR, which has been used to solve many under-sampling problems in the past ten years, is adopted. Our approach can effectively detect a target embedded in sea clutter as well as multiple adjacent targets and distinguish them from each other. Results obtained using real data with opportunistic targets validate our approach. Therefore, the proposed 2-D SR-MUSIC approach improves target detection and outperforms conventional cascaded methods.
Autors: Zezong Chen;Chao He;Chen Zhao;Fei Xie;
Appeared in: IEEE Geoscience and Remote Sensing Letters
Publication date: Nov 2017, volume: 14, issue:11, pages: 1983 - 1987
Publisher: IEEE
 
» Enhancement for High-Speed Switching of Magneto-Optic Fiber-Based Routing Using Single Magnetizing Coil
Abstract:
This paper discusses a compact and faster technique to switch magneto-optics (MO) routing systems. The new design utilizes a single coil to generate in-phase and out-of-phase magnetic fields to magnetize and demagnetize the MO material. Because of the use of high-current pMOS and nMOS transistors, along with a single coil, this new circuit enhances the switching speed and minimizes the package size. The authors have shown with experimental results that the proposed magnetic field generator circuit can produce forward and reverse magnetic fields to aid the MO material to switch faster.
Autors: Jayaprakash Selvaraj;Wei Shen Theh;Neelam Prabhu Gaunkar;Jiayu Hong;Leif H Bauer;Mani Mina;
Appeared in: IEEE Transactions on Magnetics
Publication date: Nov 2017, volume: 53, issue:11, pages: 1 - 4
Publisher: IEEE
 
» Enhancement of the Magnetoelectric Effect in Multiferroic CoFe2O4/PZT Bilayer by Induced Uniaxial Magnetic Anisotropy
Abstract:
In this paper, we have compared magnetic, magnetostrictive, and piezomagnetic properties of isotropic and anisotropic cobalt ferrite pellets. The isotropic sample was prepared by the ceramic method while the sample exhibiting uniaxial anisotropy was made by reactive sintering using spark plasma sintering (SPS). This technique permits us to induce a magnetic anisotropy in cobalt ferrite in the direction of the applied pressure during the SPS process. Sample with uniaxial anisotropy revealed a higher longitudinal magnetostriction and piezomagnetism compared with the isotropic sample, but the transversal magnetostriction and piezomagnetism were dramatically reduced. In the case of magnetoelectric (ME) layered composite, the ME coefficient is directly related to the sum of the longitudinal and transversal piezomagnetic coefficients. These two coefficients being opposite in sign, the use of material exhibiting high longitudinal and low transversal piezomagnetic coefficient (or vice versa) in ME devices is expected to improve the ME effect. Hence, ME bilayer devices were made using isotropic and anisotropic cobalt ferrite stuck with a lead zirconate titanate layer. ME measurements at low frequencies revealed that bilayer with anisotropic cobalt ferrite exhibits an ME coefficient three times higher than a bilayer with isotropic cobalt ferrite. We also investigated the behavior of such composites when excited at resonant frequency.
Autors: Alex Aubert;Vincent Loyau;Frédéric Mazaleyrat;Martino LoBue;
Appeared in: IEEE Transactions on Magnetics
Publication date: Nov 2017, volume: 53, issue:11, pages: 1 - 5
Publisher: IEEE
 
» Enhancement of Transient Two-States Characteristics in Metal-Insulator-Semiconductor Structure by Thinning Metal Thickness
Abstract:
In this work, the Al/SiO2/p-Si metal-insulator-semiconductor structures with various metal thicknesses were fabricated. The charging/discharging transient current behaviors during sweeping or switching the voltages have been studied. By thinning down partial portion of the gate metal to 10 nm, the steady state leakage current was found decreased because the high resistivity of the ultrathin metal causing lower fringing field effect. Also, the transient currents were found enhanced. The reasons were that there were minority carriers under the ultrathin metal contributing to the transient currents. The above properties make the device having better volatile memory characteristics.
Autors: Kuan-Hao Tseng;Chien-Shun Liao;Jenn-Gwo Hwu;
Appeared in: IEEE Transactions on Nanotechnology
Publication date: Nov 2017, volume: 16, issue:6, pages: 1011 - 1015
Publisher: IEEE
 
» Enhancing Capacity in Compact MIMO-OFDM Systems With Frequency-Selective Matching
Abstract:
Mutual coupling among receive antennas can profoundly reduce capacity in multiple-input, multiple-output (MIMO) systems. Prior work has shown that these losses can often be significantly reduced by using sophisticated antenna matching at the receiver. However, previous studies have focused exclusively on frequency non-selective matching, and rely on assumptions that are valid only for small bandwidths. In this paper, we consider the capacity of broadband MIMO-OFDM systems with coupled receive antennas. We present upper and lower bounds on the best capacity that can be achieved by physically realizable, frequency-selective antenna matching. The upper and lower bounds coincide for most antenna configurations considered in the examples, and thus determine the performance of capacity-optimal matching. These results suggest that frequency-selective matching can significantly increase capacity in the presence of strong coupling. Moreover, these gains can be achieved by a simple class of matching networks that are easily realized in hardware.
Autors: Lopamudra Kundu;Brian L. Hughes;
Appeared in: IEEE Transactions on Communications
Publication date: Nov 2017, volume: 65, issue:11, pages: 4694 - 4703
Publisher: IEEE
 
» Enhancing MongoDB with Purpose-Based Access Control
Abstract:
Privacy has become a key requirement for data management systems. Nevertheless, NoSQL datastores, namely highly scalable non relational database management systems, which often support data management of Internet scale applications,still do not provide support for privacy policies enforcement. With this work, we begin to address this issue, by proposing an approach for the integration of purpose based policy enforcement capabilities into MongoDB, a popular NoSQL datastore. Our contribution consists of the enhancement of the MongoDB role based access control model with privacy concepts and related enforcement monitor. The proposed monitor is easily integrable into any MongoDB deployment through simple configurations. Experimental results show that our monitor enforces purpose-based access control with low overhead.
Autors: Pietro Colombo;Elena Ferrari;
Appeared in: IEEE Transactions on Dependable and Secure Computing
Publication date: Nov 2017, volume: 14, issue:6, pages: 591 - 604
Publisher: IEEE
 
» Enhancing Responsivity and Detectevity of Si-ZnO Photodetector With Growth of Densely Packed and Aligned Hexagonal Nanorods
Abstract:
High-performance photodiodes are desirable for ultrahigh speed optical communication and highresolution optical instrumentation. This paper reports both theoretical and experimental optimization approaches for low-cost chemothermal growth of hexagonal nanorods on Si-ZnO heterojunction. The alignments of nanorods were made by controlling the etching rate with the addition of 2% isopropyl alcohol during the process. The formation of nanorods were found to be linear, densely packed, and uniformly distributed on ZnO thin film as seen from SEM images and X-ray Diffraction (XRD) pattern. The X-ray Photoelectron Spectroscopy result shows the absence of carbon contamination and confirms the elemental composition of ZnO. The current–voltage measurement confirms ohmic junction between the nanostructure and ZnO thin film enhancing the increase of photocurrent, which provides high responsivity. The proposed fabrication process opens up the possibility of realization of low-cost, high-performance, and future flexible optoelectronics sensor circuitry.
Autors: Santanu Maity;Deboraj Muchahary;Partha Pratim Sahu;
Appeared in: IEEE Transactions on Nanotechnology
Publication date: Nov 2017, volume: 16, issue:6, pages: 939 - 945
Publisher: IEEE
 
» Envelope Control for Four-Wheel Independently Actuated Autonomous Ground Vehicle Through AFS/DYC Integrated Control
Abstract:
This paper proposes an envelope control framework for four-wheel independently actuated autonomous ground vehicle (AGV) to regulate it on desired path and simultaneously control it to the driving limits. The envelope control framework is achieved based on the integrated control of active front-wheel steer and direct yaw-moment control. In a speed controller, the G-G diagram is used to describe the driving limits on each path segment. The desired traction and braking force is calculated according to the G-G diagram and desired path. In a path-following controller, a feedforward–feedback lateral controller is designed to calculate the desired steering angle to follow the desired path. In a yaw-moment controller, the β–r phase portraits are utilized to describe the handling limits. The yaw-moment controller aims at keeping the AGV from losing stability in limit driving, which is calculated through a sliding mode controller and provided by the independent motors actuation. Through an independent driving technique, the tyre cornering stiffness is estimated online based on the predefined Magic Formula model to improve the controller's robustness. An autonomous Formula Student racecar developed by the authors is used as testbed. The autonomous driving experiments on racetrack validate the efficiency of the proposed controller.
Autors: Jun Ni;Jibin Hu;Changle Xiang;
Appeared in: IEEE Transactions on Vehicular Technology
Publication date: Nov 2017, volume: 66, issue:11, pages: 9712 - 9726
Publisher: IEEE
 
» Epitaxial ScAlN Etch-Stop Layers Grown by Molecular Beam Epitaxy for Selective Etching of AlN and GaN
Abstract:
Although selective dry etches exist for GaN, it is difficult to selectively etch AlN in heterostructures with other conventional III-N epitaxial materials. The reduction in etch rate resulting from the addition of 2%–16% scandium to ScxAl1–xN in conventional Cl2/BCl3/Ar inductively coupled plasma etching is presented. Smooth, epitaxial ScxAl1–xN layers are grown by RF-plasma-assisted molecular beam epitaxy directly on 4H-SiC substrates. The etch selectivity with respect to AlN is as high as 10.6 and 11.2 for and 0.16, respectively, allowing ScxAl1–xN to act as an etch-stop layer with minimal misfit strain when grown within either AlN or GaN based heterostructures.
Autors: Matthew T. Hardy;Brian P. Downey;David J. Meyer;Neeraj Nepal;David F. Storm;D. Scott Katzer;
Appeared in: IEEE Transactions on Semiconductor Manufacturing
Publication date: Nov 2017, volume: 30, issue:4, pages: 475 - 479
Publisher: IEEE
 
» Equalization Method of the Wireless Power Transfer in an Electronic Shelf Label Power Supply System
Abstract:
In a wireless power transmission device that drives multiple power outputs for electronic shelf labels (ESLs), we propose a novel rail transformer design for use with a 50/60 Hz power supply. By periodically short circuiting the receiving coils located closest to the transmitting coil, we experimentally verified that power can be transmitted to each ESL in a significantly uniform fashion. We expect the present approach with periodically switched receiver coils to be much more convenient, reliable, and flexible than our previous method of physically adjusting the air gaps between coils. In verification experiments, the output power of three receiving coils in a prototype was equalized at a level of approximately 60 mW. Without periodic switching, the output power of the center receiving coil only reached 40 mW, whereas, the receiving coils closest to the transmitting coils reached an output level of 80 mW, with output power fluctuating by approximately 49%. This paper demonstrates an effective design strategy for wireless power transfer devices.
Autors: Yinggang Bu;Subhas Chandra Mukhopadhyay;
Appeared in: IEEE Transactions on Magnetics
Publication date: Nov 2017, volume: 53, issue:11, pages: 1 - 5
Publisher: IEEE
 
» Equilibrium Analysis of Markup Pricing Strategies Under Power Imbalance and Supply Chain Competition
Abstract:
This study uses a game-theory-based analytical model to examine the consequences of two markup pricing schemes, fixed-dollar markup and percentage markup, in a supply chain-to-chain competition setting with power imbalance between dominant retailers. Our results show that the equilibrium pricing strategy depends on the level of supply chain-to-chain competition. Specifically, if the level of supply chain competition is not sufficiently high, the equilibrium pricing strategy for the two retailers will be the one in which both retailers choose to adopt the percentage markup pricing policy, i.e., the [PP] strategy. Unfortunately, this equilibrium will lead the retailers into the prisoner's dilemma in some common situations. However, if the level of competition is extremely high, the equilibrium pricing strategy will be that where the leader (Retailer 1) chooses the percentage markup pricing policy and the follower (Retailer 2) selects the fixed-dollar markup pricing policy, i.e., the [PF] strategy. This equilibrium pricing strategy always hurts Manufacturer 1, but might benefit Manufacturer 2 when the level of competition exceeds a certain threshold. From the perspective of the end-consumers, they prefer the level of competition to be kept below a certain threshold such that the [PP] strategy becomes the equilibrium pricing strategy because this equilibrium leads to the lowest retail prices. Furthermore, our results show that Retailer 1 suffers a first-mover disadvantage even under a linear demand curve, and this situation cannot be alleviated by abandoning its price-leader position to share power equally with Retailer 2.
Autors: Yao-Yu Wang;Zhongsheng Hua;Jian-Cai Wang;Fujun Lai;
Appeared in: IEEE Transactions on Engineering Management
Publication date: Nov 2017, volume: 64, issue:4, pages: 464 - 475
Publisher: IEEE
 
» Ernst Werner Von Siemens and the Early Evolution and Diffusion of Electric Telegraphy [Scanning Our Past]
Abstract:
The technology of electric telegraphy that revolutionized long-distance communication and established the groundwork for later innovations, such as telephone, fax machine, and internet, emerged in the 1830s and 1840s thanks to the work of many men of science and technology around the world. In 1799, Alessandro Volta’s invention of reliable storage electric currents which allowed their use in controlled conditions, and the demonstration two decades later of a connection between electricity and magnetism by Hans Christian Oersted, supported the experimentation which led to a communication system by which electric signals were transmitted over a wire laid between stations.
Autors: Simón Reif-Acherman;
Appeared in: Proceedings of the IEEE
Publication date: Nov 2017, volume: 105, issue:11, pages: 2274 - 2284
Publisher: IEEE
 
» Errata to “Using Wearable Technology to Generate Objective Parkinson’s Disease Dyskinesia Severity Score: Possibilities for Home Monitoring”
Abstract:
In the above paper [1], the affiliation for M. Delrobaei was listed incorrectly. The affiliation should have appeared as follows:
Autors: Mehdi Delrobaei;Navid Baktash;Greydon Gilmore;Kenneth McIsaac;Mandar Jog;
Appeared in: IEEE Transactions on Neural Systems and Rehabilitation Engineering
Publication date: Nov 2017, volume: 25, issue:11, pages: 2214 - 2214
Publisher: IEEE
 
» Erratum to "Low-Cost Collaborative Mobile Charging for Large-Scale Wireless Sensor Networks"
Abstract:
The authors of "Low-Cost Collaborative Mobile Charging for Large-Scale Wireless Sensor Networks" which appeared in August issue of this journal [ibid., vol. 16, no. 8, pp. 2213–2227, Aug. 2017] would like to correct a typo that occurred in Fig. 1. The numbers above the X axis were wrong. The corrected Fig. 1 is provided
Autors: Tang Liu;Baijun Wu;Hongyi Wu;Jian Peng;
Appeared in: IEEE Transactions on Mobile Computing
Publication date: Nov 2017, volume: 16, issue:11, pages: 3278 - 3278
Publisher: IEEE
 
» Error Performance Optimization Using Logarithmic Barrier Function in Molecular Nanonetworks
Abstract:
The performance of a molecular signal detector relies on selected value of the detection threshold. In fact, arbitrary choice of detection threshold would increase either the probability of miss detection or the probability of false alarm. Thereby, an appropriate value of detection threshold is required in order to optimize the error performance of a realistic diffusion-based molecular communication (DbMC) system. For this, we come up with a new approach that yields optimal value for convex optimization problem in DbMC using logarithmic barrier followed by modified Karush–Kuhn–Tucker conditions, Newton Raphson method, and finally rounding the solution to the nearest integer value. Previous works on threshold optimization in DbMC either give suboptimal solution or optimal one whereof the convergence depends on choosing the smallest interval that contains the optimal value. Numerical and simulation results reveal that our proposed methodology can provide optimal solution with utmost accuracy in few iterations.
Autors: Satish K. Tiwari;Tadi Ravi Teja Reddy;Prabhat K. Upadhyay;
Appeared in: IEEE Communications Letters
Publication date: Nov 2017, volume: 21, issue:11, pages: 2408 - 2411
Publisher: IEEE
 
» Error-Free Text Typing Performance of an Inductive Intra-Oral Tongue Computer Interface for Severely Disabled Individuals
Abstract:
For severely paralyzed individuals, alternative computer interfaces are becoming increasingly essential for everyday life as social and vocational activities are facilitated by information technology and as the environment becomes more automatic and remotely controllable. Tongue computer interfaces have proven to be desirable by the users partly due to their high degree of aesthetic acceptability, but so far the mature systems have shown a relatively low error-free text typing efficiency. This paper evaluated the intra-oral inductive tongue computer interface (ITCI) in its intended use: Error-free text typing in a generally available text editing system, Word. Individuals with tetraplegia and able bodied individuals used the ITCI for typing using a MATLAB interface and for Word typing for 4 to 5 experimental days, and the results showed an average error-free text typing rate in Word of 11.6 correct characters/min across all participants and of 15.5 correct characters/min for participants familiar with tongue piercings. Improvements in typing rates between the sessions suggest that typing ratescan be improved further through long-term use of the ITCI.
Autors: Lotte N. S. Andreasen Struijk;Bo Bentsen;Michael Gaihede;Eugen R. Lontis;
Appeared in: IEEE Transactions on Neural Systems and Rehabilitation Engineering
Publication date: Nov 2017, volume: 25, issue:11, pages: 2094 - 2104
Publisher: IEEE
 
» eSES: Enhanced Simple Energy Saving for LTE HeNBs
Abstract:
This letter proposes enhanced simple energy saving (eSES), a simple yet novel scheme, that turns off the RF module of inactive low-power LTE Home evolved Node B (HeNBs), and accurately wakes up these dormant HeNBs when there are connection requests. The eSES does not modify the 3rd Generation Partnership Project (3GPP) specifications, and can co-exist with other HeNBs that do not exercise the eSES. We show that the eSES effectively saves the energy consumption of a dormant HeNB at the cost of moderately increasing the connection time of the first call request to the HeNB.
Autors: Yi-Bing Lin;Li-Chang Wang;Wei-Cheng Chen;
Appeared in: IEEE Communications Letters
Publication date: Nov 2017, volume: 21, issue:11, pages: 2520 - 2523
Publisher: IEEE
 
» Estimation of Basis Line-Integrals in a Spectral Distortion-Modeled Photon Counting Detector Using Low-Rank Approximation-Based X-Ray Transmittance Modeling: K-Edge Imaging Application
Abstract:
Photon counting detectors (PCDs) provide multiple energy-dependent measurements for estimating basis line-integrals. However, the measured spectrum is distorted from the spectral response effect (SRE) via charge sharing, K-fluorescence emission, and so on. Thus, in order to avoid bias and artifacts in images, the SRE needs to be compensated. For this purpose, we recently developed a computationally efficient three-step algorithm for PCD-CT without contrast agents by approximating smooth X-ray transmittance using low-order polynomial bases. It compensated the SRE by incorporating the SRE model in a linearized estimation process and achieved nearly the minimum variance and unbiased (MVU) estimator. In this paper, we extend the three-step algorithm to K-edge imaging applications by designing optimal bases using a low-rank approximation to model X-ray transmittances with arbitrary shapes (i.e., smooth without the K-edge or discontinuous with the K-edge). The bases can be used to approximate the X-ray transmittance and to linearize the PCD measurement modeling and then the three-step estimator can be derived as in the previous approach: estimating the x-ray transmittance in the first step, estimating basis line-integrals including that of the contrast agent in the second step, and correcting for a bias in the third step. We demonstrate that the proposed method is more accurate and stable than the low-order polynomial-based approaches with extensive simulation studies using gadolinium for the K-edge imaging application. We also demonstrate that the proposed method achieves nearly MVU estimator, and is more stable than the conventional maximum likelihood estimator in high attenuation cases with fewer photon counts.
Autors: Okkyun Lee;Steffen Kappler;Christoph Polster;Katsuyuki Taguchi;
Appeared in: IEEE Transactions on Medical Imaging
Publication date: Nov 2017, volume: 36, issue:11, pages: 2389 - 2403
Publisher: IEEE
 
» Estimation of Magnetocardiography Current Sources Using Reconstructed Magnetic Field Data
Abstract:
We propose a new method of estimating magnetocardiography (MCG) current sources using reconstructed magnetic field data. Because, our MCG sensors were arranged in a 2-D plane, they could only detect the magnetic field data generated in front of the torso, which leads to estimation of blurred source imaging from deep sources. In this paper, we reconstructed the magnetic field data that cannot be detected by the MCG sensors. The locations of the reconstructed magnetic field data were also in a 2-D plane and parallel to the sensor array. The proposed method shows that it reduced the current-source extension and enhanced the spatial resolution for deep sources. We evaluated the current-source extension and spatial resolution at R peak. The active regions of the ventricular depolarization and repolarization were obtained using time integration with the current sources estimated at QRS complex and T wave, respectively. The proposed method can estimate high spatial resolution source imaging, especially for current sources that are far from the MCG sensors.
Autors: Wenxu Sun;Koichiro Kobayashi;
Appeared in: IEEE Transactions on Magnetics
Publication date: Nov 2017, volume: 53, issue:11, pages: 1 - 4
Publisher: IEEE
 
» Estimation of Performance Metrics at Signalized Intersections Using Loop Detector Data and Probe Travel Times
Abstract:
This paper introduces a simple but practical approach that uses both loop detector data and probe travel times for computing the vehicle hours traveled (VHT), average delay, and level of service (LOS) for signalized intersections. The goal is to improve upon the state-of-the-practice method outlined in the highway capacity manual (HCM) by incorporating additional travel time measurements from probe vehicles or vehicle re-identification systems. The proposed methodology is designed to work under a variety of traffic conditions, including states of congestion in which the HCM methodology is not reliable. Our analysis is then tested using simulation of an arterial site in Arcadia, CA, USA. The results suggest that the proposed methodology performs better at the approach level than at the lane group level. Population size and probe penetration rate are two key parameters in the estimation. Either a large population size or a high penetration rate is required in order to produce reliable estimates of VHT, delay, and LOS. Results also show that the proposed methodology only requires 7% of the penetration rate to outperform the HCM methodology.
Autors: Qijian Gan;Gabriel Gomes;Alexandre Bayen;
Appeared in: IEEE Transactions on Intelligent Transportation Systems
Publication date: Nov 2017, volume: 18, issue:11, pages: 2939 - 2949
Publisher: IEEE
 
» Evaluating Software Project Managers: A Multidimensional Perspective
Abstract:
A qualified and motivated project manager is a key factor in a software project’s success. Thus, getting the most out of those managers is important. Feedback is a critical part of this process. With this in mind, this article recommends the best practices for evaluating software project managers.
Autors: Lawrence Peters;Ana M. Moreno;
Appeared in: IEEE Software
Publication date: Nov 2017, volume: 34, issue:6, pages: 104 - 108
Publisher: IEEE
 
» Evaluation Method for Multidegree-of-Freedom Spherical Actuators Under Power Control
Abstract:
Multidegree-of-freedom (multi-DOF) actuators have been developed for the fields of robotics and industrial machinery. In general, an actuating system with multi-DOF is composed of single-DOF actuators, which results in large, heavy, and complicated structures. Therefore, multi-DOF actuators are expected to become a key technology to solve these problems, and various actuators have been proposed and evaluated using their own methods. However, evaluation methods for absolute comparisons of the actuators have not been proposed. In order to evaluate the characteristics of the spherical synchronous actuators under the same condition, an evaluation method based on a torque equation and singular value decomposition is proposed. The proposed method can evaluate the static torque characteristics using a torque area that is composed of torques around arbitrary axes. The effectiveness of the proposed method is verified by comparing the static torque characteristics of several spherical actuators.
Autors: Kazuaki Takahara;Katsuhiro Hirata;Noboru Niguchi;Yusuke Nishiura;Yo Sakaidani;
Appeared in: IEEE Transactions on Magnetics
Publication date: Nov 2017, volume: 53, issue:11, pages: 1 - 5
Publisher: IEEE
 
» Evaluation Methodology for Fast Switching Cloud RAN Systems
Abstract:
The switching scheme between base band units (BBUs) and remote radio heads (RRHs) is a key point in a cloud radio access network (C-RAN). Fast BBU-RRH switching schemes will play crucial roles in future flexible C-RAN systems. In this letter, an evaluation model is proposed to analyze the performance of fast switching schemes. Based on the model, we also propose an evaluation methodology through jointly taking backlogs, idle resources, and switching costs into account. The evaluation methodology provides guidance on future design for fast switching schemes. Finally, the effectiveness of the proposed methodology is validated by simulation results.
Autors: Yaxin Wang;Xin Zhang;Dacheng Yang;
Appeared in: IEEE Communications Letters
Publication date: Nov 2017, volume: 21, issue:11, pages: 2404 - 2407
Publisher: IEEE
 
» Evaluation of a Heterogeneous Multicore Architecture by Design and Test of an OFDM Receiver
Abstract:
This paper presents an evaluation of a Heterogeneous Multicore Architecture (HMA) by implementing Orthogonal Frequency-Division Multiplexing (OFDM) receiver blocks as designs for the test of functionality. OFDM receiver consists of computationally intensive and general-purpose processing tasks that can provide maximum coverage to test and evaluate a massively-parallel as well as a general-purpose platform like the HMA. The blocks of the receiver are primarily designed by crafting template-based Coarse-Grained Reconfigurable Array (CGRA) devices and then arranging them in a sequence over a Network-on-Chip (NoC) structure along with a few RISC cores for complete OFDM processing. The OFDM blocks such as Fast Fourier Transform (FFT) and Time Synchronization are computationally intensive and require parallel processing. The OFDM receiver also contains tasks such as frequency offset estimation which require the processing of Taylor series and CORDIC algorithms that are serial in nature. Such a combination of serial and parallel algorithms can perform a thorough exploration and evaluation of almost all the design features of an HMA. The OFDM implementation has led to scale CGRAs to different dimensions, instantiate Processing Elements (PEs) as multiple arithmetic resources and to establish almost all possible ways of PE interconnections. It further explores time-multiplexed patterns for data placement in the CGRA memories. Nevertheless, the data can also be exchanged among different nodes over NoC structure simultaneously and independently by using direct memory access devices. In this experimental work, the performance of each CGRA, the collective performance of the whole platform and the NoC traffic are recorded in terms of the number of clock cycles and several high-level performance metrics. Today's HMAs are generally over or under resourced for the applications that they are designed for and thus not an optimal choice for the end user. Apart from t- e interesting comparisons to the other state-of-the-art, our experimental setup has provided important insight and guidelines that the designers can use to implement near-optimal solutions for their target applications.
Autors: Sajjad Nouri;Waqar Hussain;Jari Nurmi;
Appeared in: IEEE Transactions on Parallel and Distributed Systems
Publication date: Nov 2017, volume: 28, issue:11, pages: 3171 - 3187
Publisher: IEEE
 
» Evaluation of Cable SGEMP Response Using Monte Carlo and Finite-Difference Time-Domain Methods
Abstract:
In this paper, the system-generated electromagnetic pulse (SGEMP) response generated on the shielded cable after X-ray irradiation in laser inertial confinement fusion facility is studied by the Monte Carlo and finite-difference time-domain (FDTD) method. A layered cable model is established according to the radiation environment in the target chamber of the SG-III laser facility, the Monte Carlo software MCNP5 is used to calculate the number of deposited charges, and a program is developed based on the FDTD method to calculate the electromagnetic field in the dielectric layer. Finally, the current response on the cable conductor is obtained using Ampere’s circuit law. The results showed that the peak current response on the cable with a length of 1 m is as large as 1.26 A with a frequency range of 0–5 GHz. Furthermore, some important parameters, such as the X-ray fluence, pulsewidth, X-ray energy, cable material, thickness of the shielding layer, and length of the cable, all have effects on the cable SGEMP.
Autors: Zhiqian Xu;Cui Meng;
Appeared in: IEEE Transactions on Nuclear Science
Publication date: Nov 2017, volume: 64, issue:11, pages: 2829 - 2836
Publisher: IEEE
 
» Evaluation of core-continuity-constrained ROADMs for flex-grid/MCF optical networks
Abstract:
To effectively keep pace with the global IP traffic growth forecasted in the years to come, flex-grid over multi-core fiber (MCF) networks can bring superior spectrum utilization flexibility, as well as bandwidth scalability far beyond the non-linear Shannon's limit. In such a network scenario, however, full node switching re-configurability will require enormous node complexity, pushing the limits of current optical device technologies with prohibitive capital expenditures. Therefore, cost-effective node solutions will most probably be the key enablers of flex-grid/MCF networks, at least in the short- and mid-term future. In this context, this paper proposes a cost-effective reconfigurable optical add/drop multiplexer (ROADM) architecture for flex-grid/MCF networks, called CCC-ROADM, which reduces technological requirements (and associated costs) in exchange for demanding core continuity along the end-to-end communication. To assess the performance of the proposed CCC-ROADM in comparison with a fully flexible ROADM (i.e., a fully non-blocking ROADM, called FNB-ROADM in this work) in large-scale network scenarios, a novel lightweight heuristic to solve the route, modulation, core, and spectrum assignment problem in flex-grid/MCF networks is presented in this work, whose goodness is successfully validated against optimal ILP formulations previously proposed for the same goal. The obtained numerical results in a significant number of representative network topologies with different MCF configurations of 7, 12, and 19 cores show almost identical network performance in terms of maximum network throughput when deploying CCC-ROADMs versus FNB-ROADMs, while decreasing network capital expenditures to a large extent.
Autors: F.-J. Moreno-Muro;R. Rumipamba-Zambrano;P. Pavón-Marino;J. Perelló;J. M. Gené;S. Spadaro;
Appeared in: IEEE/OSA Journal of Optical Communications and Networking
Publication date: Nov 2017, volume: 9, issue:11, pages: 1041 - 1050
Publisher: IEEE
 
» Evaluation of Correlation Between Orientation of Y3Fe5O12 (YIG) Thin Film and Spin Seebeck Effect
Abstract:
We found that the orientation of the magnetic material yttrium–iron–garnet (YIG) depends on the type of substrate. The orientation of YIG was evaluated using an orientation index. We obtained experimental results suggesting that the orientation of YIG is related to the saturation value of the generated voltage by the spin Seebeck effect and the diffusion length of the spin current. The diffusion length of the spin current is proportional to the orientation index.
Autors: Atsushi Yamamoto;Makoto Arai;Tetsuya Takimoto;Masatoshi Itoh;Shizutoshi Ando;Shigeru Saito;Takayuki Kawahara;
Appeared in: IEEE Transactions on Magnetics
Publication date: Nov 2017, volume: 53, issue:11, pages: 1 - 4
Publisher: IEEE
 
» Evaluation of Exchange Stiffness From Temperature-Dependent Magnetization in ZnFe2O4 Thin Films
Abstract:
Nano-crystalline magnetic ZnFe2O4 thin films were deposited in oxygen atmosphere at different substrate temperatures (TS) on amorphous quartz substrate by pulsed laser deposition technique. The TS = 350 °C film was also annealed at different temperatures in air. X-ray diffraction patterns confirmed that all the samples were cubic spinel and the average grain size of the films increased with increasing TS and annealing temperatures (TA). Spontaneous magnetization at different temperature was obtained from the – loops. The temperature dependence of magnetization data was fit using Bloch’s law. The value of exchange stiffness constant (D) was calculated using the fit values of Bloch’s constant. The obtained D values were found to gradually decrease with the increase of average grain size.
Autors: B. N. Sahu;R. Prabhu;N. Venkataramani;Shiva Prasad;R. Krishnan;
Appeared in: IEEE Transactions on Magnetics
Publication date: Nov 2017, volume: 53, issue:11, pages: 1 - 4
Publisher: IEEE
 
» Evaluation of Macro Diversity Gain in Long Range ALOHA Networks
Abstract:
Macro reception diversity is a capability allowing a packet to be received by several base stations. In this letter, we propose a simple but accurate analytical model to estimate the macro diversity gain in pure and slotted ALOHA wireless networks. The proposed model takes into account Rayleigh fading, shadowing, and capture effect. We obtain simple closed-form formulas for the network packet loss rate. We find that systems with macro reception diversity can benefit from shadowing. With path loss exponent 4, packet loss rate constraint 10% and 8 dB shadowing, the capacity of pure ALOHA with macro diversity is at least 2 times as much as that in systems in which a device transmits only to the best base station.
Autors: Qipeng Song;Xavier Lagrange;Loutfi Nuaymi;
Appeared in: IEEE Communications Letters
Publication date: Nov 2017, volume: 21, issue:11, pages: 2472 - 2475
Publisher: IEEE
 
» Evaluation of Preventive Maintenance Segregation: A Multi Factorial Study
Abstract:
Recently, several papers on preventive maintenance (PM) have shown that segregation of PM’s can be beneficial when it comes to improving factory performance. However, these were limited to either cases of equal PM segregation and/or without consideration of other factors and operating conditions such as incurred setup or the number of tools in the toolset. In this paper, we extend previous work in this area in two major respects. First, we consider the more realistic case of PM segregation into equal or unequal portions and second, we evaluate the impact of PM segregation under various operating conditions via simulation. Our simulation experiments provide insight and guidelines for practitioners in planning the PM activity such that the overall performance is improved.
Autors: Adar A. Kalir;Kosta Rozen;James R. Morrison;
Appeared in: IEEE Transactions on Semiconductor Manufacturing
Publication date: Nov 2017, volume: 30, issue:4, pages: 508 - 514
Publisher: IEEE
 
» Event-Triggered Global Robust Output Regulation for a Class of Nonlinear Systems
Abstract:
This note studies the global robust output regulation problem for a class of nonlinear systems by an output-based event-triggered control law. First, we convert the problem into the event-triggered global robust stabilization problem of a well-defined augmented system based on the internal model approach. Then, we design an output-based event-triggered control law together with an output-based event-triggered mechanism to solve the stabilization problem, which in turn leads to the solution to the original problem by an output-based event-triggered control law. Finally, we illustrate our approach by an example.
Autors: Wei Liu;Jie Huang;
Appeared in: IEEE Transactions on Automatic Control
Publication date: Nov 2017, volume: 62, issue:11, pages: 5923 - 5930
Publisher: IEEE
 
» Event-Triggered State Estimation: An Iterative Algorithm and Optimality Properties
Abstract:
This paper investigates the optimal design of event-triggered estimation for linear systems. The synthesis approach is posed as a team decision problem where the decision makers are given by the event trigger and the estimator. The event-trigger decides upon its available measurements whether the estimator shall obtain the current state information by transmitting it through a resource constrained channel. The objective is to find the optimal tradeoff between the mean square estimation error and the expected number of transmissions over a finite horizon. After deriving basic characteristics of the optimal solution, we propose an iterative algorithm that alternates between optimizing one decision maker while fixing the other and vice versa. By analyzing the dynamical behavior of the iterative method, it is shown that the algorithm converges to a symmetric threshold policy for first-order systems if the statistics of the uncertainties are even and unimodal. In the case of bimodal distributions, we show numerically that the iterative method may find asymmetric threshold policies that outperform symmetric rules.
Autors: Adam Molin;Sandra Hirche;
Appeared in: IEEE Transactions on Automatic Control
Publication date: Nov 2017, volume: 62, issue:11, pages: 5939 - 5946
Publisher: IEEE
 
» Everything You Wanted to Know About PUFs
Abstract:
In typical cryptographic applications, the secret keys are stored in volatile or nonvolatile memory (NVM). In the latter case, they remain in memory and can be retrieved even when the power is turned off. Even volatile memory is vulnerable to attacks if one has physical access to it. Thus the traditional approaches to key storage are not favored, especially in high-security applications.
Autors: Shital Joshi;Saraju P. Mohanty;Elias Kougianos;
Appeared in: IEEE Potentials
Publication date: Nov 2017, volume: 36, issue:6, pages: 38 - 46
Publisher: IEEE
 
» Evolution and Impact of Defects in a p-Channel CCD After Cryogenic Proton-Irradiation
Abstract:
The p-channel charge coupled devices (CCDs) have been shown to display improved tolerance to radiation-induced charge transfer inefficiency when compared with n-channel CCDs. However, the defect distribution formed during irradiation is expected to be temperature dependent due to the differences in lattice energy caused by a temperature change. This has been tested through defect analysis of two p-channel e2v CCD204 devices, one irradiated at room temperature and one at a cryogenic temperature (153 K). Analysis is performed using the method of single trap pumping. The dominant charge trapping defects at these conditions have been identified as the donor level of the silicon divacancy and the carbon interstitial defect. The defect parameters are analyzed both immediately postirradiation and following several subsequent room-temperature anneal phases up until a cumulative anneal time of approximately 10 months. We have also simulated charge transfer in an irradiated CCD pixel using the defect distribution from both the room-temperature and cryogenic case, to study how the changes affect imaging performance. The results demonstrate the importance of cryogenic irradiation and annealing studies, with large variations seen in the defect distribution when compared to a device irradiated at room-temperature, which is the current standard procedure for radiation-tolerance testing.
Autors: Daniel Wood;David J. Hall;Jason Gow;Jesper Skottfelt;Neil J. Murray;Konstantin Stefanov;Andrew D. Holland;
Appeared in: IEEE Transactions on Nuclear Science
Publication date: Nov 2017, volume: 64, issue:11, pages: 2814 - 2821
Publisher: IEEE
 
» Evolution of Surface Plasmon Supermodes in Metal-Clad Microwire and Its Potential for Biosensing
Abstract:
A finite-element method based on the vector H-field formulation in conjunction with perturbation techniques is used to study metal-clad microwire waveguides for bio-sensing applications. Sensors are designed to detect DNA hybridization through the change of the effective index and attenuation constant of the waveguide structure. The key parameters, such as effective index, loss coefficient, and spot sizes, are presented and potential sensor applications are discussed.
Autors: Nina Siti Aminah;Christos Themistos;Rahmat Hidayat;Mitra Djamal;B. M. A. Rahman;
Appeared in: Journal of Lightwave Technology
Publication date: Nov 2017, volume: 35, issue:21, pages: 4684 - 4691
Publisher: IEEE
 
» Evolutionary Approach to Solve a Novel Time-Domain Cavity Problem
Abstract:
The problem of forced oscillations in a cavity filled with a dynamic plasma is solved in the time domain in compliance with the principle of causality. Interaction of the plasma and the cavity field is driven by the motion equation where the field is present in the Lorentz force standing at its right-hand side. The solution has a form of the modal expansions. Every term herein is a product of two multipliers. One is the vector element of the modal basis dependent on coordinates only. The basis is obtained as an eigenvector set of a self-adjoint operator specially selected from Maxwell’s equations. The operator is specified as a merger of the differential procedure and the boundary conditions over perfectly conducting cavity surface. The basis elements are derived with their physical dimensions, i.e., volt per meter and ampere per meter. The other factor is a scalar dimension-free time-dependent modal amplitude. A system of evolutionary equations (i.e., with time derivative) for the modal amplitudes is derived and solved explicitly under the initial conditions. The problem is solved in the Hilbert space of real-valued functions of coordinates and time.
Autors: Fatih Erden;
Appeared in: IEEE Transactions on Antennas and Propagation
Publication date: Nov 2017, volume: 65, issue:11, pages: 5918 - 5931
Publisher: IEEE
 
» Exact Synthesis of Majority-Inverter Graphs and Its Applications
Abstract:
We propose effective algorithms for exact synthesis of Boolean logic networks using satisfiability modulo theories (SMTs) solvers. Since exact synthesis is a difficult problem, it can only be applied efficiently to very small functions, having up to six variables. Key in our approach is to use majority-inverter graphs (MIGs) as underlying logic representation as they are simple (homogeneous logic representation) and expressive (contain AND/OR-inverter graphs) at the same time. This has a positive impact on the problem formulation: it simplifies the encoding as SMT constraints and also allows for various techniques to break symmetries in the search space due to the regular data structure. Our algorithm optimizes with respect to the MIG’s size or depth and uses different ways to encode the problem and several methods to improve solving time, with symmetry breaking techniques being the most effective ones. We discuss several applications of exact synthesis and motivate them by experiments on a set of large arithmetic benchmarks. Using the proposed techniques, we are able to improve both area and delay after lookup table (LUT)-based technology mapping beyond the current results achieved by state-of-the-art logic synthesis algorithms.
Autors: Mathias Soeken;Luca Gaetano Amarù;Pierre-Emmanuel Gaillardon;Giovanni De Micheli;
Appeared in: IEEE Transactions on Computer-Aided Design of Integrated Circuits and Systems
Publication date: Nov 2017, volume: 36, issue:11, pages: 1842 - 1855
Publisher: IEEE
 
» Exchange Bias Induced by the Spin Glass-Like Surface Spins in Sputter Deposited Fe3O4 Thin Films
Abstract:
The exchange bias in the reactive sputtered polycrystalline Fe3O4 thin films of thicknesses 50 and 150 nm is studied. X-ray diffraction, laser Raman, and selected area electron diffraction studies confirm the formation of the Fe3O4 single phase. The high-resolution transmission electron microscope images show the presence of well-defined crystallites. The presence of the exchange bias effect is mainly due to the existence of a significant exchange coupling between the core spins and the spin glass-like surface spins of the grains. The temperature dependence of the magnitude of the exchange bias field shows two exponential regimes of which the lower temperature regime corresponds to the spin freezing effect below 50 K. The first magnetization curves measured after zero field cooling show S-shape below the spin freezing temperature. The presence of superparamagnetism and spin freezing has been investigated through the field cooled (FC) and zero FC magnetization measurements. Temperature dependence of coercivity also indicates the spin freezing effect. Hence, the observed large exchange bias of the samples at lower temperatures is due to the freezing of the surface spins.
Autors: P. V. Muhammed Shameem;Laxman Mekala;M. Senthil Kumar;
Appeared in: IEEE Transactions on Magnetics
Publication date: Nov 2017, volume: 53, issue:11, pages: 1 - 5
Publisher: IEEE
 
» Experiencing the Sights, Smells, Sounds, and Climate of Southern Italy in VR
Abstract:
This article explores what it takes to make interactive computer graphics and VR attractive as a promotional vehicle, from the points of view of tourism agencies and the tourists themselves. The authors exploited current VR and human-machine interface (HMI) technologies to develop an interactive, innovative, and attractive user experience called the Multisensory Apulia Touristic Experience (MATE). The MATE system implements a natural gesture-based interface and multisensory stimuli, including visuals, audio, smells, and climate effects.
Autors: Vito M. Manghisi;Michele Fiorentino;Michele Gattullo;Antonio Boccaccio;Vitoantonio Bevilacqua;Giuseppe L. Cascella;Michele Dassisti;Antonio E. Uva;
Appeared in: IEEE Computer Graphics and Applications
Publication date: Nov 2017, volume: 37, issue:6, pages: 19 - 25
Publisher: IEEE
 
» Experimental Analysis of Nonlinear Impairments in Fibre Optic Transmission Systems up to 7.3 THz
Abstract:
An effective way of increasing the overall optical fibre capacity is by expanding the bandwidth used to transmit signals. In this paper, the impact of expanding the transmission bandwidth on the optical communication system is experimentally studied using the achievable rates as a performance metric. The tradeoffs between the use of larger bandwidths and higher nonlinear interference (NLI) noise is experimentally and theoretically analyzed. The growth of NLI noise is investigated for spectral bandwidths from 40 GHz up to 7.3 THz using 64-QAM and Nyquist pulse-shaping. Experimental results are shown to be in line with the predictions from the Gaussian-noise model showing a logarithmic growth in NLI noise as the signal bandwidth is extended. A reduction of the information rate of only 10% was found between linear and nonlinear transmission across several transmission bandwidths, increasing up to 7.3 THz. Finally, the power transfer between channels due to stimulated Raman scattering effect is analyzed showing up to 2-dB power tilt at optimum power for the largest transmitted bandwidth of 7.3 THz.
Autors: Gabriel Saavedra;Mingming Tan;Daniel J. Elson;Lidia Galdino;Daniel Semrau;Md. A Iqbal;Ian D. Phillips;Paul Harper;Andrew Ellis;Benn C. Thomsen;Domaniç Lavery;Robert I. Killey;Polina Bayvel;
Appeared in: Journal of Lightwave Technology
Publication date: Nov 2017, volume: 35, issue:21, pages: 4809 - 4816
Publisher: IEEE
 
» Experimental and Analytical Study of Single-Phase Squirrel-Cage Induction Motor Considering End-Ring Porosity Rate
Abstract:
Single-phase squirrel-cage induction motors are widely used in household and industrial electronics, because of their simplicity, low cost, and ruggedness. The cage rotor of the induction motor is produced using laminated electrical steel sheets subjected to die-casting processes with various manufacturing parameters. However, the die-casting process generates pores in the cage-rotor end-ring. These pores have a significant effect on the motor properties, which cannot be accurately analyzed. In this paper, squirrel-cage rotors with different porosities were prepared by varying the die-casting process. Then, the end-ring porosity was accurately analyzed using X-ray computed tomography. The inter-bar resistance of the squirrel-cage rotor was calculated from the end-ring porosity rate. Finite-element analysis (FEA) was used to predict the effects of porosity on the motor performance. Finally, the motor was tested, and the measurements were compared with the FEA-predicted results. The analytical and experimental results obtained for a 1.5 kW single-phase squirrel-cage induction motor were very similar, when the end-ring porosity was included in the analysis.
Autors: Kyu-Seok Lee;Sung-Ho Lee;Jung-Hyung Park;Jeong-Man Kim;Jang-Young Choi;
Appeared in: IEEE Transactions on Magnetics
Publication date: Nov 2017, volume: 53, issue:11, pages: 1 - 4
Publisher: IEEE
 
» Experimental and Numerical Study of the Behavior of a Multilayer for Active Magnetic Refrigerator Based on La-Fe-Co-Si
Abstract:
This paper is dedicated to study the experimental validation of a numerical model based on La-Fe-Co-Si layered operating near room temperature. For the purpose of this paper, a numerical simulation based on the transient energy equations is proposed for modeling the heat exchange between the multilayer material and the carrier fluid in the regenerator bed with an applied magnetic field of 1.5 T. The main findings of the simulation show a comparison between the numerical model and experimental setup including the magnetocaloric effect of La-Fe-Co-Si, pressure drop, and exergy and exergetic efficiency.
Autors: Younes Chiba;
Appeared in: IEEE Transactions on Magnetics
Publication date: Nov 2017, volume: 53, issue:11, pages: 1 - 4
Publisher: IEEE
 
» Experimental Characterization of a Three-Rod Magnetostrictive Device for Energy Harvesting
Abstract:
Energy harvesting allows the conversion of environmental energy into electrical energy to feed low-power consumption electronics. In particular, this method can be exploited to supply wireless sensors nodes for structural health monitoring (SHM) when the electric network source is not present. Indeed, vibrations induced by vehicle traffic on a bridge could be converted into electrical energy, but suitable devices are needed. This paper presents experimental tests over a device based on three Galfenol rods, where electrical and magnetic parameters are changed and tested with different mechanical sources in order to seek the best performance.
Autors: Carmine Stefano Clemente;Daniele Davino;Ciro Visone;
Appeared in: IEEE Transactions on Magnetics
Publication date: Nov 2017, volume: 53, issue:11, pages: 1 - 4
Publisher: IEEE
 
» Experimental Comparison of Probabilistic Shaping Methods for Unrepeated Fiber Transmission
Abstract:
This paper studies the impact of probabilistic shaping on effective signal-to-noise ratios (SNRs) and achievable information rates (AIRs) in a back-to-back configuration and in unrepeated nonlinear fiber transmissions. For the back-to-back setup, various shaped quadrature amplitude modulation (QAM) distributions are found to have the same implementation penalty as uniform input. By demonstrating in transmission experiments that shaped QAM input leads to lower effective SNR than uniform input at a fixed average launch power, we experimentally confirm that shaping enhances the fiber nonlinearities. However, shaping is ultimately found to increase the AIR, which is the most relevant figure of merit, as it is directly related to spectral efficiency. In a detailed study of these shaping gains for the nonlinear fiber channel, four strategies for optimizing QAM input distributions are evaluated and experimentally compared in wavelength division multiplexing (WDM) systems. The first shaping scheme generates a Maxwell–Boltzmann (MB) distribution based on a linear additive white Gaussian noise channel. The second strategy uses the Blahut–Arimoto algorithm to optimize an unconstrained QAM distribution for a split-step Fourier method based channel model. In the third and fourth approach, MB-shaped QAM and unconstrained QAM are optimized via the enhanced Gaussian noise (EGN) model. Although the absolute shaping gains are found to be relatively small, the relative improvements by EGN-optimized unconstrained distributions over linear AWGN optimized MB distributions are up to 59%. This general behavior is observed in 9-channel and fully loaded WDM experiments.
Autors: Julian Renner;Tobias Fehenberger;Metodi P. Yankov;Francesco Da Ros;Søren Forchhammer;Georg Böcherer;Norbert Hanik;
Appeared in: Journal of Lightwave Technology
Publication date: Nov 2017, volume: 35, issue:22, pages: 4871 - 4879
Publisher: IEEE
 
» Experimental Evaluation of the Static Characteristics of Multi-Degree-of-Freedom Spherical Actuators
Abstract:
Multi-degree-of-freedom (multi-DOF) actuators have been developed to be applied in the fields of robotics and industrial machinery. In general, an actuating system with several-DOF is composed of single-DOF motors, which results in large, heavy, and complicated structures. Therefore, multi-DOF actuators are expected to solve these problems, and various actuators have been studied. Unlike single-DOF motors, the multi-DOF actuators can generate torque in various directions at different positions. Due to this, it is difficult to measure the static torque characteristics. In this paper, a measuring method of the torque constant is proposed in order to measure the static torque characteristics. This method can be used to evaluate the static torque characteristics over an entire movable range by measuring only a limited number of points. Finally, the effectiveness of this method is discussed.
Autors: Kazuaki Takahara;Katsuhiro Hirata;Noboru Niguchi;Yusuke Nishiura;Yo Sakaidani;
Appeared in: IEEE Transactions on Magnetics
Publication date: Nov 2017, volume: 53, issue:11, pages: 1 - 5
Publisher: IEEE
 
» Experimental Study of Iron Losses Generated by a Uniform Rotating Field
Abstract:
This paper introduces a mock-up with a solid iron cylinder rotating in a fixed excitation frame powered by dc current. A uniform field is created in the rotating cylinder, which is driven by an external motor. The braking torque is measured, allowing the study of iron losses generated by a uniform rotating field. The aim is to advance toward a vector iron loss model that takes into account different magnetization directions and their interdependency. The eddy current losses are the dominant loss source in the mock-up, rendering it easier to model. A standard eddy currents model is proposed. It models well the losses at low and medium magnetic flux density, but lower losses are measured near saturation levels. This could be due to the high thickness to radius ratio changing the eddy current paths near the edges of the rotor, which can be later analyzed by a full 3-D finite-element method analysis. A 2-D finite-element method simulation is performed, which estimates the magnetic flux heterogeneity in the rotor. Several lessons are drawn from this mock-up, which prepares a second version with a higher speed and a longer laminated stack rotor. A higher air gap will decrease the voltage fluctuation in the primary winding, a smaller angular opening of the excitation frame will improve the uniformity of the flux in the rotor.
Autors: A. Bernot;A. Giraud;Y. Lefèvre;J.-F. Llibre;
Appeared in: IEEE Transactions on Magnetics
Publication date: Nov 2017, volume: 53, issue:11, pages: 1 - 5
Publisher: IEEE
 
» Experimental Verification of Effects in an Emergency Stop by Installation of Magnetorheological Fluid Damper to an Elevator
Abstract:
In the countries sailing with an economic tailwind, many skyscrapers are going up. These buildings require systems of high-speed, safety, and comfortable elevators for its speedy vertical transportation. If the drives of elevator fail, an emergency stop device is supposed to work immediately for saving passengers lives in the elevator cage, because the elevator has outrageous potential energy to the ground level and kinetic energy. Its dangerousness is nothing compared to that in railways as surface transport. In order to reduce impact force to passengers in emergency stoppage, the authors had already proposed a safe and dependable magnetorheological fluid (MRF) semi-active damper (i.e., MRF damper) put between an emergency stop device and an elevator cage. In this paper, in order to evaluate the effects of the MRF damper, we would like to make up a test installation, which is composed of an MRF damper, a spring, an elevator cage, linear servo mechanics with a ball screw for generating the brake force of emergency stop device, sensors, and a digital controller with Labview. In addition, we would like to verify the validity of our system by many experiments.
Autors: Naoki Kobayashi;Keisuke Kawase;Shunsuke Sato;Toshiko Nakagawa;
Appeared in: IEEE Transactions on Magnetics
Publication date: Nov 2017, volume: 53, issue:11, pages: 1 - 4
Publisher: IEEE
 
» Explicit Construction of AG Codes From a Curve in the Tower of Bassa-Beelen-Garcia-Stichtenoth
Abstract:
We present multi-point algebraic geometric codes overstepping the Gilbert-Varshamov bound. The construction is based on a curve in the tower introduced by Bassa et al. These codes are described in detail by constructing generator matrices. It turns out that these codes have nice properties similar to those of Hermitian codes. The duals are also such codes and can be expressed as an explicit formula.
Autors: Chuangqiang Hu;
Appeared in: IEEE Transactions on Information Theory
Publication date: Nov 2017, volume: 63, issue:11, pages: 7237 - 7246
Publisher: IEEE
 

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