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Calculation and Optimization of ITER Upper VS Feeder Under an Electromagnetic Load

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Plasma Science and Technology 2014年第11期16卷 1063-1067页

作者：汪献伟谢飞金环 Institute of Plasma Physics Chinese Academy of Sciences department of Electronic and information engineering Shunde Polytechnic

The upper vertical stability （VS） feeder is a part connected to the upper VS coil by a welding joint. The function of the feeder is to transfer current and coolant water to the VS coil. A giant electron^agnetic force will be generated during normal operation by the current flowing in the VS coils, interacting with the external background field. The Lorentz force will induce Tresca stress in the feeder. The amplitudes of the magnetic field and Lorentz force along the conductor running direction have been calculated based on Maxwell＇s equations. To extract the Tresca stress in the feeder, a finite element model was created using the software ANSYS and an electromagnetic load was applied on the model. According to the analytical design, the stresses were classified and evaluated based on ASME. In order to reduce the Tresca stress, some optimization works have been done and the Tresca stress has had a significant reduction in the optimized model. This analytical work figured out the stress distribution in the feeder and checked the feasibility of the prototype design model. The ANSYS analysis results will provide a guidance for later improvement and fabrication.

关键词： ITER magnetic field electromagnetic force feeder elliptical integral Trescastress

Improved Hybrid Beamforming for mmWave Multi-User Massive MIMO

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Computers, Materials & Continua 2021年第6期67卷 3057-3070页

作者： Ji-Sung Jung Won-Seok Lee Yeong-Rong Lee Jaeho Kim Hyoung-Kyu Song department of information and Communication engineering and Convergence engineering for Intelligent Drone Sejong UniversitySeoul05006Korea department of Electrical engineering Sejong UniversitySeoul05006Korea

Massive multiple input multiple output(MIMO)has become essential for the increase of capacity as the millimeter-wave(mmWave)communication is considered.Also,hybrid beamforming systems have been studied since full-digital beamforming is impractical due to high cost and power consumption of the radio frequency(RF)chains.This paper proposes a hybrid beamforming scheme to improve the spectral efciency for multi-user MIMO(MU-MIMO)systems.In a frequency selective fading environment,hybrid beamforming schemes suffer from performance degradation since the analog precoder performs the same precoding for all subcarriers.To mitigate performance degradation,this paper uses the average channel covariance matrix for all subcarriers and considers an iterative algorithm to design analog precoder using approximation techniques.The analog precoder is iteratively updated for each column until it converges.The proposed scheme can reduce errors in the approximating process of the overall spectral efciency.This scheme can be applied to fully-connected and partially-connected structures.The simulation results show that spectral efciency performance for the proposed scheme is better than the conventional schemes.The proposed scheme can achieve similar performance with full-digital beamforming by using a sufciently large number of RF chains.Also,this paper shows that the proposed scheme outperforms other schemes in the frequency selective fading environment.This performance improvement can be achieved in both structures.

关键词： Hybrid precoding massive MIMO MU-MIMO mmwave frequency selective fading

A synchronous duty-cycled reservation based MAC protocol for underwater wireless sensor networks

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Digital Communications and Networks 2021年第3期7卷 385-398页

作者： Alak Roy Nityananda Sarma department of information Technology Tripura UniversityWest TripuraIndia department of Computer Science and engineering Tezpur UniversityAssamIndia

To design an energy-efficient Medium Access Control(MAC)protocol for the Underwater Wireless Sensor Networks(UWSNs)is an urgent research issue since depleted batteries cannot be recharged or replaced in the underwater environment.Moreover,the underwater acoustic channels are affected by hindrances such as long propagation delay and limited bandwidth,which appear in the design of the MAC protocol for the UWSNs.The available MAC protocols for the terrestrial wireless sensor networks exhibit low performance in energy efficiency,throughput and reliability in the UWSNs,and cannot be used in the UWSNs directly because of their unique characteristics.This paper proposes a synchronous duty-cycled reservation-based MAC protocol named Ordered Contention MAC(OCMAC)protocol.The basic mechanism of this protocol is to schedule data transmission by transmitters through the scheduling of Ready To Send(RTS)frames.The protocol eliminates the possible collision during data transmission and improves communication efficiency.The paper analyzes the performance in energy efficiency,throughput and reliability of the protocol by modeling the queuing behavior of OCMAC with a Markov Chain process.Furthermore,the analytical model is validated through a simulation study.The analysis results demonstrated that while providing good throughput and reliability,OCMAC can achieve energy saving.

关键词： Underwater wireless sensor networks MAC protocol Energy efficiency Throughput Reliability Acoustic communication OCMAC

Distributed Certificateless Key Encapsulation Mechanism Secure Against the Adaptive Adversary

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Journal of Shanghai Jiaotong university(Science) 2009年第1期14卷 102-106页

作者：龙宇李祥学陈克非洪璇 department of Computer Science and engineering Shanghai Jiaotong UniversityShanghai 200240China School of information security engineering Shanghai Jiaotong UniversityShanghai 200240China State Key Laboratory of Integrated Service Networks Xidian UniversityXi'an 710071China

This paper proposes an adaptively secure solution to ce(?)tificateless distributed key encapsulation mechanism from pairings by using Canetti's adaptive secure key generation scheme based on discrete logarithm. The proposed scheme can withstand adaptive attackers that can choose players for corruption at any time during the run of the protocol,and this kind of attack is powerful and realistic.In contrast,all previously presented threshold certificateless public key cryptosystems are proven secure against the more idealized static adversaries only.They choose and fix the subset of target players before running the protocol.We also prove security of this scheme in the random oracle model.

关键词：封装机制自适应分布式公开密钥密码体制密钥生成离散对数安全播放器

Harmful Intrusion Detection Algorithm of Optical Fiber Pre-Warning System Based on Correlation of Orthogonal Polarization Signals

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Photonic Sensors 2017年第3期7卷 226-233页

作者： Fukun BI Chong FENG Hongquan QU Tong ZHENG Chonglei WANG School of Electrical and information engineering North China University of Technology Beijing 100144 China Beijing Institute of Technology department of information and Electronic Beijing 100081 China

At present, advanced researches of optical fiber intrusion measurement are based on the constant false alarm rate （CFAR） algorithm. Although these conventional methods overcome the interference of non-stationary random signals, there are still a large number of false alarms in practical applications. This is because there is no specific study on orthogonal polarization signals of false alarm and intrusion. In order to further reduce false alarms, we analyze the correlation of optical fiber signals using birefringence of single-mode fiber. This paper proposes the harmful intrusion detection algorithm based on the correlation of two orthogonal polarization signals. The proposed method uses correlation coefficient to distinguish false alarms and intrusions, which can decrease false alarms. Experiments on real data, which are collected from the practical environment, demonstrate that the difference in correlation is a robust feature. Furthermore, the results show that the proposed algorithm can reduce the false alarms and ensure the detection performance when it is used in optical fiber pre-warning system （OFPS）.

关键词： Optical fiber birefringence orthogonal polarization signals correlation

PCNN Model Analysis and Its Automatic Parameters Determination in Image Segmentation and Edge Detection

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Chinese Journal of Electronics 2014年第1期23卷 97-103页

作者： DENG Xiangyu MA Yide School of information Science and engineering Lanzhou University School of Electronics and information engineering Lanzhou Institute of Technology

The Pulse coupled neural network(PCNN)has been widely used in digital image processing, but the automatic parameters determination is still a difficult aspect, which becomes the focus of PCNN research. In this paper, by the classical solution to difference equations and the time-domain analysis of PCNN model, we provide the expressions of the firing time and the firing period of neurons, and reveal the "mathematics firing" phenomenon of PCNN. Based on this, we propose a new method of automatic parameters determination based on both eliminating the "mathematics firing" and getting the highest efficiency of PCNN. We also present an edge detection model on the basis of image segmentation of PCNN and a method to determine automatically the parameters of the model. Experimental results prove the validity and efficiency of our proposed algorithm for the segmentation and the edge detection of the test images.

关键词： Pulse coupled neural network(PCNN) model Neuron firing mechanism Parameters determination Image segmentation Edge detection model

Accurate and efficient molecular dynamics based on machine learning and non von Neumann architecture

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npj Computational Materials 2022年第1期8卷 1001-1015页

作者： Pinghui Mo Chang Li Dan Zhao Yujia Zhang Mengchao Shi Junhua Li Jie Liu College of Electrical and information engineering Hunan UniversityChangshaHunanPR China department of Electrical and Computer engineering University of WashingtonSeattleWAUSA

Force field-based classical molecular dynamics(CMD)is efficient but its potential energy surface(PES)prediction error can be very large.Density functional theory(DFT)-based ab-initio molecular dynamics(AIMD)is accurate but computational cost limits its applications to small systems.Here,we propose a molecular dynamics(MD)methodology which can simultaneously achieve both AIMD-level high accuracy and CMD-level high efficiency.The high accuracy is achieved by exploiting deep neural network(DNN)’s arbitrarily-high precision to fit PES.The high efficiency is achieved by deploying multiplication-less DNN on a carefully-optimized special-purpose non von Neumann(NvN)computer to mitigate the performance-limiting data shuttling(i.e.,‘memory wall bottleneck’).By testing on different molecules and bulk systems,we show that the proposed MD methodology is generally-applicable to various MD tasks.The proposed MD methodology has been deployed on an in-house computing server based on reconfigurable field programmable gate array(FPGA),which is freely available at http://nvnmd.***.vip.

关键词： server computer dynamics

Advanced Strategies of Passivating Perovskite Defects for High-Performance Solar Cells

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Energy & Environmental Materials 2021年第3期4卷 293-301页

作者： Chuang Sun Lei Xu Xilin Lai Zhengping Li Ming He department of Electronic information engineering Anhui UniversityHefei 230031China department of Microelectronics Peking UniversityBeijing 100871China

Organic–inorganic halide perovskite(OIHP)solar cells have garnered great attention in the last decade since they continuously approach the Shockley–Queisser Limit.Compared with conventional organic and inorganic semiconductors,OIHPs possess the high tolerance on defects due to the dominated intrinsically shallow-level carrier-trapping centers.However,the existence of defects still causes the ion migration,produces the hysteresis effect,and accelerates the film degradation,eventually suppressing the device efficiency and stability.In this Review Article,we summarize recent impressive advance on passivating OIHP defects and discuss the future horizon of exploiting high-efficiency and long-stability OIHP solar cells in terms of defect managements.

关键词： defects film morphology organic-inorganic hybrid perovskites passivation

Shadow detection combining characters of human vision

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Journal of Central South University 2014年第2期21卷 659-667页

作者：李建锋邹北骥李玲芝高焕芝 School of information Science and engineering Central South University School of information Science and engineering Jishou University

A shadow detection method using pulse couple neural network inspired by the characters of human visual system is proposed.More precisely,lateral inhibition of human vision and coefficient of variation are combined together to improve the pulse couple neural network.Shadow detection is considered to be a shadow region segmentation problem.Experiment shows that the presented method is consistent with human vision compared to shadow detection methods based on HSV and pulse couple neural network(PCNN) by both subjective and objective assessments.

关键词：人类视觉系统阴影检测脉冲耦合神经网络字符测相变异系数区域分割 PCNN