Electronics Letters
Volume 53, Issue 14, 06 July 2017
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Volume 53, Issue 14
06 July 2017
- Features
- Acoustical engineering
- Antennas and propagation
- Biomedical technology
- Circuits and systems
- Control engineering
- Electromagnetism
- Image and vision processing and display technology
- Information and communications
- Circuits and systems
- Microwave technology
- Optical communication
- Photonics
- Power electronics, energy conversion and sustainability
- Radar, sonar and navigation
- Semiconductor technology
- Speech and audio processing and translation
- Wireless communications
- Antennas and propagation
- Wireless communications
- Errata
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- Source: Electronics Letters, Volume 53, Issue 14, page: 896 –896
- DOI: 10.1049/el.2017.2341
- Type: Article
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- Source: Electronics Letters, Volume 53, Issue 14, page: 896 –896
- DOI: 10.1049/el.2017.2327
- Type: Article
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- Source: Electronics Letters, Volume 53, Issue 14, page: 897 –897
- DOI: 10.1049/el.2017.2340
- Type: Article
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in brief
interview
a very cool band
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- Author(s): Zhenhai Yan ; Feiran Yang ; Jun Yang
- Source: Electronics Letters, Volume 53, Issue 14, p. 899 –900
- DOI: 10.1049/el.2017.1115
- Type: Article
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To improve the performance for identifying the block sparse system, a block sparse reweighted zero-attracting normalised least mean square algorithm (NLMS) (BS-RZA-NLMS) is proposed in this Letter. The proposed algorithm is derived by applying block sparsity constraint on the cost function of the NLMS, which is a log-sum penalty of adaptive tap weights with equal block partition sizes. The convergence behaviour of the BS-RZA-NLMS is analysed in terms of the zero attraction and block partition. Simulation results demonstrate the performance advantage of the proposed algorithm in the context of block sparse system identification.
Block sparse reweighted zero-attracting normalised least mean square algorithm for system identification
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- Author(s): H. Saeidi-Manesh ; M. Mirmozafari ; G. Zhang
- Source: Electronics Letters, Volume 53, Issue 14, p. 901 –902
- DOI: 10.1049/el.2017.1282
- Type: Article
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A method of beam matching between two linear polarised radiation patterns of a dual-polarised frequency scanning antenna is proposed, implemented, and tested. A meticulous phase match process between the outputs of both individual cells and the whole corresponding horizontal and vertical feed lines is carried out. To verify the simulation results and to take the coupling effect into account, the radiation patterns of an isolated column, as well as those of three columns, are measured. In agreement with the design and with the simulation results, horizontal and vertical polarisation beams with a pointing angle mismatch of less than ±0.2° within the resonant frequency bandwidth of 2.75–2.95 GHz are achieved.
- Author(s): Yueshu Xu ; Qian Ye ; Guoxiang Meng
- Source: Electronics Letters, Volume 53, Issue 14, p. 903 –904
- DOI: 10.1049/el.2017.1357
- Type: Article
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The Misell algorithm is an effective phase-retrieval holography method for measuring the surface error of large reflector antennas. However, it is investigated experimentally to have a low accuracy at low signal-to-noise ratio (SNR). To decrease the great sensitivity to noise of Misell algorithm, a new iterative Fourier filtering approach based on autocorrelation theorem is proposed. The iterative Fourier filtering approach is used to remove some of the imperfection present in far-field amplitude data. The computer simulation results of Shanghai Sheshan-25m-telescope model show that the proposed approach improved the accuracy of Misell algorithm at low SNR obviously.
- Author(s): Congsi Wang ; Yan Wang ; Wei Wang ; Jinzhu Zhou ; Meng Wang ; Zhihai Wang
- Source: Electronics Letters, Volume 53, Issue 14, p. 904 –906
- DOI: 10.1049/el.2017.1072
- Type: Article
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A new structure and scattering array factor coupling model, for estimating the effect of element position error of active phased-array antenna on its radar cross section (RCS) is established, based on the relationship between structural position error and phase difference. The model greatly reduces the computational complexity of the RCS for the evaluation of array antenna performance. Based on the model, the influence of the element position error on the gain and RCS is analysed with the results showing that a reasonable reduction in element position accuracy may effectively decrease the RCS. Thus, the developed model can be applied in engineering to balance the radiation and scattering properties. With the necessary radiation and scattering performance guaranteed, the antenna processing and installation tolerances can be properly relaxed to effectively reduce the calibration difficulty and cost.
- Author(s): I. Ndip ; M. Huhn ; F. Brandenburger ; C. Ehrhardt ; M. Schneider-Ramelow ; H. Reichl ; K.D. Lang ; H. Henke
- Source: Electronics Letters, Volume 53, Issue 14, p. 906 –908
- DOI: 10.1049/el.2016.3673
- Type: Article
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In this Letter, the authors present the experimental verification of an analytical model, which captures the realistic shape of bond wire antennas (BWAs) in dependence on the wire bonding and design parameters. Using the verified model, the impact of the shape of the wires on the performance of BWAs is quantified.
Low cross-polarisation high-isolation frequency scanning aperture coupled microstrip patch antenna array with matched dual-polarisation radiation patterns
Iterative Fourier filtering approach for phase-retrieval holography based on autocorrelation theorem
Electromechanical coupling based influence of structural error on radiation and scattering performance of array antennas
Experimental verification and analysis of analytical model of the shape of bond wire antennas
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- Author(s): J. Park ; J. Lee ; B. Lee ; A.S.Y. Poon ; S. Lee ; S. Kim
- Source: Electronics Letters, Volume 53, Issue 14, p. 908 –910
- DOI: 10.1049/el.2017.1506
- Type: Article
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The Salisbury-screen characteristics of the human abdomen are demonstrated. The skin–fat–muscle structure in the human abdomen resembles that of the Salisbury screen, which consists of a resistive sheet, a dielectric slab, and a conducting plane. Using this similarity, the authors can estimate the degree of obesity based on the reflectivity of electromagnetic waves. The Salisbury screen acts as a wave absorber when the thickness of the dielectric matches the quarter wavelength. This characteristic is similar to the human abdominal structure. Fat, which has much lower conductivity than skin or muscle, plays the role of the dielectric in the Salisbury screen. Therefore, by measuring the frequency where reflection is minimised, fat thickness can be estimated.
Measuring abdominal fatness using principle of Salisbury screen
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- Author(s): J. Lim ; H. Kim ; H. Oh ; S. Kang
- Source: Electronics Letters, Volume 53, Issue 14, p. 910 –912
- DOI: 10.1049/el.2017.1243
- Type: Article
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Three-dimensional integrated systems that combine large-capacity dynamic random access memory (DRAM) with high-performance processors represent a promising solution to implementing high-performance computing. However, in such configurations stacked DRAM cells will inevitably be exposed to high temperatures generated by the processor, thereby necessitating DRAMs with high refresh rates driven by embedded temperature sensors. In this Letter, a thermally aware refresh-control method that accounts for abrupt changes in temperature and thermal distribution using low-power techniques such as dynamic voltage frequency scaling is proposed. Comparisons with previous systems via single- and eight-core simulations reveal that the proposed method improves efficiency with no additional overhead.
- Author(s): Kejun Wu and Huazi Zhang
- Source: Electronics Letters, Volume 53, Issue 14, p. 912 –914
- DOI: 10.1049/el.2017.1167
- Type: Article
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A novel group-delay-insensitive linear equaliser (GDILE) is proposed to reduce the eye-skew in four-level pulse amplitude modulation (PAM-4) receivers. With a cross-coupled positive-feedback degeneration network, the proposed GDILE employs additional pole and zero into its transfer function to reduce the group-delay variation with frequency. Simulation results shows a 40 Gbit/s PAM-4 receiver that employs a GDILE that can reduce the eye-skew by 73% compared with the conventional linear equaliser with a modest increase of power consumption.
Dynamic voltage frequency scaling-aware refresh management for 3D DRAM over processor architecture
Group-delay-insensitive linear equaliser for reducing eye-skew in PAM-4 receivers
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- Author(s): I.H. Kim ; J.H. Yook ; Y.I. Son
- Source: Electronics Letters, Volume 53, Issue 14, p. 914 –916
- DOI: 10.1049/el.2017.1301
- Type: Article
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A robust speed controller for a time-delay DC motor system is presented under large delay time uncertainty. Unlike a recent result relying on a disturbance observer on the slave side of the system, a new delay compensator is devised and combined with a lowpass filter to improve its robustness against uncertain delay times and external disturbances. The effectiveness of the proposed method is tested through comparative simulations and experiments using a testbed system.
Robust predictor-based DC motor speed control under uncertain time delay
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- Author(s): H.H. Park ; K. Seo ; Y.-K. Kwon ; H.-B. Park
- Source: Electronics Letters, Volume 53, Issue 14, p. 916 –918
- DOI: 10.1049/el.2017.0524
- Type: Article
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A reliable numerical modelling for shielding evaluation of on-package conformal shields based on the integrated circuit (IC)-stripline method is presented. As a pilot test, the effects of the number of grounding pads and the thickness of a conformal shield on the shielding performance are investigated. For validation, the conformal shield is fabricated and measured by both the IC-stripline method and TEM cell method.
Shielding evaluation of on-package conformal shields by numerical modelling and experimental measurement
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- Author(s): Jiabao Wang ; Yang Li ; Zhuang Miao ; Yulong Xu ; Gang Tao
- Source: Electronics Letters, Volume 53, Issue 14, p. 918 –920
- DOI: 10.1049/el.2017.0523
- Type: Article
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Deep feature representation is widely used in various visual applications. However, the feature extracted by the convolutional neural networks (CNNs) is inappropriate for cosine similarity measurement. Because the classical CNNs are designed for classification rather than for similarity comparison. A novel cosine loss function for learning deep discriminative features, which are fit to the cosine similarity measurement, is designed. The loss can constrain the distribution of the features in the same class to be in a narrow angle region. Furthermore, a discriminative feature learning network framework and its corresponding two-stage learning method to learn the parameters is proposed. Experimental results show that the proposed method achieves state-of-the-art performance on the public Cifar10 and Market1501 datasets.
- Author(s): YuXuan Wu ; GaoYun An ; YiQiong Zhang
- Source: Electronics Letters, Volume 53, Issue 14, p. 920 –922
- DOI: 10.1049/el.2017.0272
- Type: Article
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A novel lite action unit (AU) convolution network (LAUCN) is proposed for automatic AU detection, which could improve the accuracy of AU detection with a few samples. (i) LAUCN could transform the manual intervened factors (i.e. gradient, pixels etc.), which identify the characteristics of two-dimensional shapes, to a hierarchical perceptron in multi-direction and multi-scale, while a small amount of samples are needed. (ii) LAUCN takes into account the core properties of facial AUs for detecting action unit more accurately, where the existence of strong co-occurrence structure indicates that the presence of one AU can be regarded as a prior for the presence of others so that the problem of subtle changes in appearance or geometry of the face will be well solved via exploiting this property. The experiments are conducted on the CK+ dataset, and the experimental results show that LAUCN can accomplish AU recognition satisfactorily and has achieved the expected results as well.
- Author(s): Dahe Liu ; Wengao Lu ; Shanzhe Yu ; Zhongjian Chen
- Source: Electronics Letters, Volume 53, Issue 14, p. 922 –924
- DOI: 10.1049/el.2017.0878
- Type: Article
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A low-power time-to-digital converter (TDC) scheme for column-level single-slope analogue-to-digital converters for infrared imager is presented. This scheme greatly improves the TDC's timing precision with a novel 3-bit fine gray counter, which makes use of multi-phase clocks from a delay-lock-loop. Aimed for 384 × 288 array size uncooled infrared imager with 17 μm pixel pitch, the TDC circuits have been developed and simulated employing 0.18 μm CMOS technology. Compared with conventional two-step TDC methods, this method saves more chip area and reduces the sampling power consumption by >50%, and also eliminates the coarse-fine inconsistency problem with a simulated ±0.1 least-significant-bit differential non-linearity performance.
Learning deep discriminative features based on cosine loss function
Lite AU convolution network driven by a small amount of samples
Low-power TDC scheme using DLL-based gray counter for infrared imagers
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- Author(s): J. Park ; I. Kim ; H.-Y. Song
- Source: Electronics Letters, Volume 53, Issue 14, p. 924 –926
- DOI: 10.1049/el.2017.1037
- Type: Article
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In this Letter, a new parity-check-concatenated (PCC) polar code construction that considers the number of minimum Hamming weight (MHW) codewords is proposed. The parity bits to reduce the number of MHW codewords as much as possible is successively constructed. The proposed construction can reduce the number of MHW codewords more than other codes. The results show that the proposed codes can outperform the other codes at a high signal-to-noise region.
- Author(s): Weiwei Shan ; Shuai Zhang ; Yukun He
- Source: Electronics Letters, Volume 53, Issue 14, p. 926 –928
- DOI: 10.1049/el.2017.1460
- Type: Article
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Side channel analysis (SCA) is effective to reveal the key of crypto devices by applying statistical analysis to a number of power traces, thus hardware countermeasure is necessary to protect the crypto circuits. A SCA-resistance methodology by machine learning trained power compensation module is proposed to compensate the probability of hamming distance (HD) of the intermediate data directly, to make it unable to be distinguished from correct and incorrect sub-key, thus providing resistance to SCA. The machine learning algorithm is used to find out the best HD redistribution mapping by using neural dynamic programming. Implemented on an AES-128 encryption algorithm circuit on a Xilinx Spartan-6 FPGA mounted on a SAKURA-G board, experimental SCA results show that it can provide more than 200 × measures to disclosure and still has no sign to reveal the advanced encryption standard (AES) sub-key. In addition, it has low power and area overhead and zero frequency overhead, thus is appropriate for hardware implementation of SCA countermeasure.
- Author(s): Jianlong Zhao ; Hua Qu ; Jihong Zhao ; Zhirong Luan ; Ya Guo
- Source: Electronics Letters, Volume 53, Issue 14, p. 928 –929
- DOI: 10.1049/el.2017.0093
- Type: Article
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This Letter investigates multi-controller placement problem for software-defined network aiming at minimising the propagation latency between switches and associated controllers. Distinct from the standard clustering-based partition approaches, a modified exemplar-based clustering method based on affinity propagation is presented to address the problem. Instead of specifying beforehand the number and locations of controllers, this method can learn the optimal number and locations of controllers adaptively according to network topology. Extensive simulation results demonstrate that the proposed method can provide more stable and accurate controller placement results in terms of latency minimisation compared with k-median and k-centre methods.
Construction of parity-check-concatenated polar codes based on minimum Hamming weight codewords
Machine learning based side-channel-attack countermeasure with hamming-distance redistribution and its application on advanced encryption standard
Towards controller placement problem for software-defined network using affinity propagation
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- Author(s): J. Lee ; J. Kim ; S.-Y. Lim ; J.-Y. Kwon ; J. Im ; S.-M. Lee ; S.E. Moon
- Source: Electronics Letters, Volume 53, Issue 14, p. 930 –931
- DOI: 10.1049/el.2017.1508
- Type: Article
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An electrical resistivity evaluation method for a pillar-shaped solid material, especially a brittle thermoelectric Bi2Te3, is presented with short compensation based on a probing apparatus with four-spring pins. The method eliminates the process of modelling a complex contact resistance, resulting in a simple but reproducible characterisation without any contamination on the surface in comparison to either a conventional paste or welding contact. Furthermore, it enables a small electrical or thermoelectric material <2 mm thick to be appropriately evaluated, which can erect and align a pillar-shaped material with electrical terminals, in spite of a small surface area. To extract the resistivity of a Bi2Te3 pillar with the volume of 2 × 2 × 1.6 mm, Alumina 6061-T6 material identical with that of Bi2Te3 was used as a reference material for the short compensation. Thus, the modelled resistance and its resistivity were 2.46 ± 0.11 mΩ and 6.15 ± 0.28 Ω-μm, respectively, in the range of 2–10 kHz, demonstrating the validity of the method.
De-embedding method-based electrical resistivity characterisation scheme for a small brittle pillar-shaped material
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- Author(s): Ying Jiang ; Bin Wei ; Yong Heng ; Xubo Guo ; Bisong Cao ; Linan Jiang
- Source: Electronics Letters, Volume 53, Issue 14, p. 931 –933
- DOI: 10.1049/el.2017.0429
- Type: Article
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A compact superconducting lowpass filter (LPF) composed of a pair of symmetrical parallel coupled lines, a cross-shaped patch and a modified E-type feeding structure is proposed. The filter is successfully designed and fabricated on MgO substrate with a compact size of 10.0 × 15.0 mm. Measured results match well with simulation results. The LPF has a 3 dB cut-off frequency of 2.18 GHz, relative stopband bandwidth of 160%, and 0.06 dB insertion loss in the passband. For attenuation level of −18.5 dB, stopband bandwidth is from 3.16 to 19.25 GHz.
- Author(s): Jie Xu ; Yinjie Cui ; Zhengbin Xu ; Jian Guo ; Cheng Qian ; Wenyuan Li
- Source: Electronics Letters, Volume 53, Issue 14, p. 933 –935
- DOI: 10.1049/el.2017.1829
- Type: Article
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A high Q-factor substrate integrated waveguide (SIW) cavity resonator and its application of X-band low phase noise oscillator is proposed. Complementary split-ring resonators are used to improve the Q-factor of the proposed resonator. The size of the resonator is reduced by using quarter-mode circular SIW cavity. The oscillator based on the proposed SIW cavity resonator can be easily designed and tested. Measured results demonstrate an output frequency of 10.11 GHz and a phase noise of −108.7 dBc/Hz at 100 kHz offset. The oscillator is also able to deliver an output power of 4.6 dBm and harmonic rejection of better than 30 dBc. The proposed oscillator is suitable for low-cost high-frequency systems.
Compact superconducting lowpass filter with wide stopband
Low phase noise oscillator based on complementary split-ring resonators loaded quarter-mode circular SIW cavity
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- Author(s): Yuze Liu ; Hui Li ; Chunjian Lyu ; Zhiwei Duan ; Yuefeng Ji
- Source: Electronics Letters, Volume 53, Issue 14, p. 935 –937
- DOI: 10.1049/el.2017.1559
- Type: Article
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A multi-layer restoration scheme in service-oriented software defined optical network (S-SDON) is proposed. First, the S-SDON architecture is introduced. Then a service variable optical equipment is designed to provide various services. Next, a multi-layer restoration scheme is proposed. Finally, an experiment is presented to show the feasibility and effectiveness of the proposed MLR scheme.
Experiment demonstration of multi-layer restoration in service-oriented software defined optical network
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- Author(s): Fengdan Xin ; Juanjuan Yan ; Qidi Liu
- Source: Electronics Letters, Volume 53, Issue 14, p. 937 –939
- DOI: 10.1049/el.2017.0125
- Type: Article
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A photonic technique for microwave frequency measurement based on stimulated Brillouin scattering (SBS) with low measurement error and large measurement range is demonstrated. In the scheme, an optical phase modulator is employed and the intensity balance between the two sidebands of the phase-modulated signal is broken by use of SBS in a fibre. The frequency measurement is achieved by detecting the existence of a microwave signal after photoelectric detection of the phase modulated signal. The measurement error is experimentally shown to be 50 MHz in a narrow measuring range of ∼1 GHz and 100 MHz in a wide range of 20 GHz.
- Author(s): Hai-Zhong Weng ; Osamu Wada ; Jun-Yuan Han ; Jin-Long Xiao ; Yue-De Yang ; Yong-Zhen Huang ; Jin Li ; Bing Xiong ; Chang-Zheng Sun ; Yi Luo
- Source: Electronics Letters, Volume 53, Issue 14, p. 939 –941
- DOI: 10.1049/el.2017.1695
- Type: Article
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A microsquare dual wavelength laser has been fabricated and applied to sub-THz emission by beating two modes. An 18 × 18 μm square AlGaInAs/InP microsquare laser combined with an optimised uni-travelling-carrier photodiode has demonstrated stable emission at 103.2 GHz.
Microwave frequency measurement based on optical phase modulation and stimulated Brillouin scattering
Sub-THz wave generation based on a dual wavelength microsquare laser
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- Author(s): X. Mou and H. Sun
- Source: Electronics Letters, Volume 53, Issue 14, p. 941 –943
- DOI: 10.1049/el.2016.3340
- Type: Article
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Multiple segmented transmitters' rail for dynamic wireless power transfer (DWPT) electric vehicles charging can supply high power transfer efficiency (PTE). The previous research discussed the vehicles’ speed is a key factor that can affect the design of the rail (especially, the distance between two neighbouring segmented transmitters T) to maximise the system's PTE. However, it finds out not the vehicle's speed, but the size of the transmitter rail can affect the design of T for optimising the PTE.
- Author(s): Haihong Huang ; Nanxia Bi ; Haixin Wang
- Source: Electronics Letters, Volume 53, Issue 14, p. 943 –945
- DOI: 10.1049/el.2017.1007
- Type: Article
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To achieve the maximum current rising rate, second-generation Experimental Advanced Superconducting Tokamak (EAST) plasma vertical displacement active feedback power supply applies voltage control mode while retaining the first-generation current tracking mode. When the power supply outputs high voltage, the accompanied frequent over-current protection will return the power to DC side, which leads to over-voltage protection, so the current limiting protection is applied. Experimental results prove that the voltage mode can greatly improve the ability to suppress vertical unstable displacement of plasma.
- Author(s): M. Girolami ; A. Bellucci ; P. Calvani ; F. Dimroth ; D.M. Trucchi
- Source: Electronics Letters, Volume 53, Issue 14, p. 945 –947
- DOI: 10.1049/el.2017.0755
- Type: Article
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Three metals (Ag, Au, and Ti) and a carbide (WC) were studied to verify their suitability to act as high-temperature electric contacts for photon-enhanced thermionic emission cathodes based on an AlGaInP/GaInP heterostructure. Transfer length method measurements, performed in the temperature range 25–350°C, showed that the lowest specific contact resistivity values were found for Au (4.0 × 10−4 Ω cm−2 @350°C) and Ti (1.2 × 10−3 Ω cm−2 @350°C). A further selection was made on the basis of film adhesion tests performed after the thermal cycles, in which Ti demonstrated an excellent mechanical robustness.
- Author(s): J.E. Huber ; J.W. Kolar ; G. Pammer
- Source: Electronics Letters, Volume 53, Issue 14, p. 947 –949
- DOI: 10.1049/el.2017.1064
- Type: Article
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A hybrid inverter concept for switch-mode power amplifiers as used, e.g. in power-hardware-in-the-loop testing is proposed. A main converter operating from the supplying DC voltage generates a multilevel output voltage by means of parallel-interleaved operation of several bridge legs and combination of the bridge leg output voltages with coupled inductors into a multilevel waveform. A second, series-connected inverter features a floating DC bus with only a fraction of the main converter's DC voltage, which enables a significantly higher switching frequency. The series inverter compensates the deviation of the main inverter's multilevel output voltage from the reference voltage, whereby pulse-width modulation with sawtooth carriers is employed, and hence defines the effective switching frequency of the hybrid inverter's overall output voltage. This allows for a higher output filter cutoff frequency and ultimately features a significant increase of the full-range system bandwidth, which improves by more than an order of magnitude for the considered 100 kVA example system compared with a conventional approach. Finally, closed-loop circuit simulations verify the high performance of the proposed system.
- Author(s): Y. Kwon and D. Ahn
- Source: Electronics Letters, Volume 53, Issue 14, p. 949 –951
- DOI: 10.1049/el.2017.0760
- Type: Article
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A zero-voltage switching topology for self-oscillating current-fed resonant inverter for wireless power transfer application is proposed. The drawback of conventional floating-capacitor connection between two differential MOSFET outputs is revealed. It turns out that the conventional connection causes severe switching loss because the MOSFET voltage has duty cycle >50%, while the current has an exact 50% duty cycle to sustain the self-oscillation. To solve the issue, the proposed self-oscillating inverter equips with two antiparallel diodes and two resonance capacitors between MOSFET output and ground, while the floating capacitor is removed. This allows dead-time of MOSFETs and zero-voltage switching, leading to significant reduction in switching loss. The operation and efficiency of the proposed circuit is demonstrated by simulation and measurements.
- Author(s): Ming Zhang ; Yuan-bo Guo ; Ze Li ; Xiao-hua Zhang
- Source: Electronics Letters, Volume 53, Issue 14, p. 951 –953
- DOI: 10.1049/el.2017.1333
- Type: Article
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The fluctuation of neutral-point potential (NPP) is an internal problem of three-level inverter. The fluctuation of NPP is investigated when the inverter, eight-switch three-phase inverter is working in fault tolerant mode. It is proved that the NPP fluctuation will cause output unbalance if the inverter is still controlled by the conventional space vector pulse-width modulation (SVPWM) strategy. Thus, a novel SVPWM considering NPP fluctuation is proposed to suppress the output unbalance. The effectiveness of the proposed method is demonstrated by the experimental results.
Analysis of multiple segmented transmitters design in dynamic wireless power transfer for electric vehicles charging
Application of the voltage control mode for second-generation EAST active feedback power supply
High-temperature electric contacts for AlGaInP/GaInP photon-enhanced thermionic emission cathodes
Hybrid inverter concept for extreme bandwidth high-power AC source
Self-oscillating current-fed inverter with low switching loss for wireless power transfer
Suppression strategy for output unbalance of eight-switch three-phase inverter
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- Author(s): Zhihui Li ; Yongshun Zhang ; Hanwei Liu ; Yiduo Guo
- Source: Electronics Letters, Volume 53, Issue 14, p. 953 –954
- DOI: 10.1049/el.2017.1549
- Type: Article
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A novel training samples selection method is proposed to improve the performance of space-time adaptive processing in non-homogeneous environments, where training samples are contaminated by interference target signals (outliers). First, the outlier component is removed from the sample covariance matrix based on clutter covariance matrix reconstruction, which utilises the clutter Capon spectrum integrated over a sector separated from the location of outlier. Secondly, the integral is calculated approximately by discrete sum method. Finally, the reconstructed clutter covariance matrix is combined with the generalised inner products algorithm to form the proposed statistics and the contaminated training samples are eliminated. Simulation results validate the effectiveness of the proposed method.
- Author(s): Ning Wang ; Zhonghao Wei ; Guangzuo Li ; Ran Wang ; Keshu Zhang ; Yirong Wu
- Source: Electronics Letters, Volume 53, Issue 14, p. 955 –956
- DOI: 10.1049/el.2017.1139
- Type: Article
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The synthetic aperture ladar (SAL) is similar to the synthetic aperture radar (SAR) while working at optical frequency, which could provide higher resolution than SAR. However, due to the shorter wavelength, the vibration of the platform and atmosphere turbulence will induce more serious phase error, which results in the defocused SAL image with lower signal-to-noise ratio. A novel approximated observation operator-based imaging method for SAL is proposed to solve an ℓq norm optimisation problem. Combined with the motion compensation method, the presented ℓq regularisation algorithm can suppress the side lobe and clutter, and improve the target-to-clutter ratio and image contrast efficiently. Also, the computational complexity is the same as the matched filtering imaging algorithm. Real airborne SAL data has been used to demonstrate the feasibility of the proposed algorithm.
- Author(s): Xinlei Chen ; Chao Fei ; Changqing Gu ; Raj Mittra
- Source: Electronics Letters, Volume 53, Issue 14, p. 956 –958
- DOI: 10.1049/el.2017.1016
- Type: Article
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Previous research on the characteristic basis function method (CBFM) has shown that the use of the ultra-wide band CBFM can efficiently solve the problem of computing the broadband monostatic radar cross-section (RCS) of a target by reducing the size of the associated impedance matrix and avoiding the repeated generation of the macro base functions. However, it is still necessary to repeatedly construct the reduced matrix at each frequency in the analysed frequency band, and an interpolation method is proposed to address this problem. It is shown that it is only needed to generate and store the reduced matrices at four frequency samples to cover the entire frequency band, and efficiently derive the reduced matrices at other frequencies via simple interpolation. Numerical results are given to demonstrate the accuracy and efficiency of the proposed method.
- Author(s): Wen Shulin and Li Shuqiu
- Source: Electronics Letters, Volume 53, Issue 14, p. 958 –960
- DOI: 10.1049/el.2017.0882
- Type: Article
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Most of the non-acoustic methods for towed array shape estimation are based on the incorrect original Paidoussis equation. A comparison between solution to the original and revised Paidoussis equation is made to prove the significance of utilising the latter. In addition, considering relative characteristics of the revised Paidoussis equation and the critical point which exists on the cylinder, the minimum length of damping section added at the end of the cylinder is derived.
Training samples selection method for space-time adaptive processing based on clutter covariance matrix reconstruction
Approximated observation operator-based ℓq regularisation algorithm for SAL imaging
Efficient technique for broadband monostatic RCS using the characteristic basis function method with polynomial interpolation
Minimum length of damping section for towed array based on revised Paidoussis equation
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- Author(s): N. Sharma and S.S. Chauhan
- Source: Electronics Letters, Volume 53, Issue 14, p. 960 –962
- DOI: 10.1049/el.2017.0157
- Type: Article
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A novel dopingless Ge-source dual metal drain double gate tunnel field effect transistor is presented with the help of work function engineering. Proposed device makes use of the dopingless concept, charge plasma for carrier doping concentration below the drain/source region that permits dynamic configuration by choosing suitable work function for drain/source metal electrode. In the proposed device, the n + drain region is divided into two parts of low and high work function. The work function of the metal nearest to the drain–channel junction is relatively higher than the other metal for creating a potential barrier for restricting the tunnelling of holes when the negative gate voltage is applied. By using low energy bandgap Ge material, the tunnelling probability and drive current of the device are increased. The proposed device offers high I ON/I OFF ratio (∼1013), smaller point subthreshold swing (SS) (∼31 mV/decade), average SS (∼43 mV/decade).
Dual metal drain Ge-source dopingless TFET with enhanced turn-ON steep subthreshold swing and high ON-current
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- Author(s): L.M. Lee ; H.H. Le ; F.R. Jean
- Source: Electronics Letters, Volume 53, Issue 14, p. 962 –964
- DOI: 10.1049/el.2017.0458
- Type: Article
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An improved hidden Markov model (HMM) adaptation method is proposed for the recognition of reduced frame rate speech. In previous studies of this kind of model adaptation, individual models were first adapted and then the adapted models were connected to form the word network for a speech recognition system. This adapting-then-connecting approach can produce transitions that skip too many states and increase insertion errors. In the proposed new method, the transition probabilities from the states of a HMM to the states of a following model are calculated by first connecting the two models to form a combined model and then adapting the transition probability matrix of the combined model. This connecting-then-adapting approach can rectify the problem of skipping too many states, and therefore reduce insertion errors. Experiments were conducted to investigate the effectiveness of the proposed method and the experimental results show that the proposed new method can obtain better recognition accuracy.
Improved hidden Markov model adaptation method for reduced frame rate speech recognition
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- Author(s): P. Chau ; Y. Lee ; T.D. Bui ; J. Shin
- Source: Electronics Letters, Volume 53, Issue 14, p. 964 –966
- DOI: 10.1049/el.2017.0040
- Type: Article
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Systematic wireless network coding has been proposed as a potential solution to solve the major drawback of high encoding/decoding complexities of random linear network coding and to increase the decoding capability. However, the complete analysis of the decoding performance has not been fully derived. In this Letter, the authors derive closed-form expressions for the decoding probability under systematic network coding (SNC) over single-hop and multi-hop wireless networks. They validate the analysis by comparing simulation results. Their formulation provides a theoretical analysis for further understanding of the SNC and can be used to improve the current upper bound for the decoding probability.
- Author(s): Fangchao Zhang ; Shaohui Sun ; Qiubin Gao
- Source: Electronics Letters, Volume 53, Issue 14, p. 966 –968
- DOI: 10.1049/el.2016.4704
- Type: Article
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Channel state information (CSI) at the base station (BS) is crucial to fully exploit the advantages of massive multiple-input multiple-output (MIMO) systems. In frequency division duplexing systems, CSI is obtained through downlink channel estimation and uplink CSI feedback. The conventional CSI acquisition scheme, which has been designed based on the beam selection principle, suffers from severe multi-user interference when same beamforming vector is selected for different user equipments (UEs), and the spatial richness of the channel cannot be captured by the selected beamforming vector for the rich scattering environment. To address such issues, a beam combination scheme is proposed by combining multiple selected beamforming vectors for each UE, where the beam combination process is divided into wideband beam group construction and subband combination coefficients acquisition. Simulation results demonstrate that the proposed scheme could achieve considerable increase in the system throughput while maintaining acceptable feedback overhead.
Analysis of decoding probability for systematic wireless network coding
Beam combination scheme for multi-user massive MIMO systems
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- Author(s): Zhiyang Liu ; Yingxin Zhao ; Hong Wu
- Source: Electronics Letters, Volume 53, Issue 14, p. 968 –970
- DOI: 10.1049/el.2016.4751
- Type: Article
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The mean co-channel interference in a distributed antenna system with virtual cells is studied, where a few surrounding remote antenna ports of each user form a virtual cell and serve the user. By assuming that time-division-multiple-access is adopted among the users with overlapping virtual cells, the positions of active users at each time slot are modelled as a Matérn point process of type II, and an upper bound of the mean interference is derived and verified by simulation. The analysis shows that the monotonicity of mean interference depends on the path-loss factor α, which highlights the importance of a carefully selection of virtual cell size according to the propagation environment.
Co-channel interference analysis of large-scale distributed antenna systems with virtual cells
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- Author(s): Huan Zhang ; Qinglin Zhao ; Fangxin Xu
- Source: Electronics Letters, Volume 53, Issue 14, p. 970 –972
- DOI: 10.1049/el.2017.1018
- Type: Article
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Frequency-domain contention (FDC) is a high-efficient distributed wireless access mechanism for wireless local area networks. However, it is very hard to achieve frequency synchronisation among multiple senders and multiple receivers, and further eliminate carrier frequency offset (CFO). As a result, when multiple users perform FDC simultaneously, CFO will cause serious miss detection and false alarm in identifying subcarriers, frequently leading to contention collisions and failures. Focusing on the integer carrier frequency offset, first theoretically analyse the impact of these contention collisions and failures on the throughput of FDC. Extensive simulations verify that the theoretical model is very accurate.
- Author(s): Bin Ren ; Yingmin Wang ; Shaohui Sun ; Yawen Zhang ; Xiaoming Dai ; Kai Niu
- Source: Electronics Letters, Volume 53, Issue 14, p. 972 –974
- DOI: 10.1049/el.2017.1133
- Type: Article
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In uplink massive multiple-input multiple-output (MIMO) systems, the conventional minimum mean square error-interference rejection combining (MMSE-IRC) signal detection algorithm needs to compute the inverse of the interference and noise covariance matrix, which incurs high computational complexity, especially when the number of antennas is large. A low-complexity MMSE-IRC signal detection algorithm based on the eigenvalue decomposition of the interference and noise covariance matrix is proposed. The proposed algorithm exploits a dimension-reduction technique to reduce the computation-intensive of the matrix inversion compared with the conventional algorithm. Meanwhile, the proposed algorithm is shown to be equivalent to the conventional MMSE-IRC algorithm under the assumption of uncorrelated interference and noise. Analysis and simulation results show the effectiveness of the proposed algorithm.
Impact of integer carrier frequency offset on the performance of frequency-domain contention
Low-complexity MMSE-IRC algorithm for uplink massive MIMO systems
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- Source: Electronics Letters, Volume 53, Issue 14, page: 974 –974
- DOI: 10.1049/el.2017.1259
- Type: Article
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- Source: Electronics Letters, Volume 53, Issue 14, page: 974 –974
- DOI: 10.1049/el.2017.1258
- Type: Article
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Erratum: Flexible traction power system adopting energy optimisation controller for AC-fed railway
Erratum: Simulating the pre- and de-emphasis of drive voltages of silicon-based micro-ring ring-modulators
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