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IEEE International Symposium on Antennas and Propagation

作者： Ke He Mengxia Yu E Zhao Guiping Li Maoyan Wang Jing Ma School of Physics University of Electronic Science and Technology of China (UESTC) Chengdu China Science and Technology on Special System Simulation Laboratory Beijing China

ISBN: (数字)9781728166704

ISBN: (纸本)9781728166704;9781728166711

A new RF coil based on microstrip Yagi-antenna for 7T magnetic resonance imaging (MRI) is presented in this paper. The RF coil element consists of a driver which is a pair of dipoles printed on the dielectric substrate and two reflectors distributed on either sides of the driver. simulation results show that the proposed 8-channel RF coil array with these elements has high magnetic field intensity and uniform magnetic field distribution in the transverse plane, and can also maintain relatively low specific absorption rate (SAR) in the human body electromagnetic model. In addition, by comparing the RF field distribution of healthy organs and diseased organs, the feasibility of 8-channel RF coil array for human body imaging in MRI system is confirmed.

关键词： Radio frequency Microstrip antenna arrays Magnetic resonance imaging Electromagnetic modeling Specific absorption rate Magnetic fields Microstrip

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Research on evaluation method of cooperative jamming effect in cognitive confrontation 1st

Research on evaluation method of cooperative jamming effect ...

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1st EAI International Conference on Artificial Intelligence for Communications and Networks, AICON 2019

作者： Ma, Jing Shi, Bin Che, Fei Zhang, Sitong Science and Technology on Special System Simulation Laboratory Beijing100854 China Harbin Engineering University Harbin150001 China

ISBN: (纸本)9783030229702

In modern warfare, due to the increasingly complex electromagnetic environment, cognitive confrontation will become the main form of war. Effective interference with enemy radars is of great importance for taking the lead in the battlefield. The evaluation of the synergistic interference effect is an important indicator to measure the performance of the interference equipment. According to the evaluation result, the interference strategy can be changed in time to achieve the best interference revenue and provide a strong guarantee for the successful penetration of the target. In this paper, the discovery probability and positioning accuracy of radar network are used as evaluation indicators to establish an evaluation model. The interference power, interference frequency, interference timing and interference pattern are used as membership functions. The distance, false alarm probability and different interference strategies are studied. The simulation shows that proper false alarm probability, closer distance and proper interference strategy can improve the interference benefit and provide a theoretical basis for obtaining the best interference effect in the actual battlefield. © ICST Institute for Computer sciences, Social Informatics and Telecommunications Engineering 2019 Published by Springer Nature Switzerland AG 2019. All Rights Reserved.

关键词： Membership functions

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A Microservices Oriented Edge Computing Framework for LVC simulation in the IoT Era

A Microservices Oriented Edge Computing Framework for LVC Si...

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2019第十一届计算机建模与仿真国际会议

作者： Wenxin Sun Yanlong Zhai Tianhong Bao Muhammad Mudassar Jun Shen Kai Yang School of Computer Science Beijing Institute of Technology School of Computing & Information Technology University of Wollongong Science and Technology on Special System Simulation Laboratory Beijing Simulation Center

Modeling and simulation are essential methods to better understand a complex system in the real world. Many simulation systems have strong demand for involving physical devices or equipment in the system to improve the fidelity. But most of the current cloud based simulation systems are designed for equipment with adequate resources and suffering from high latency for their centralized communication. Edge computing is getting much attention as a new paradigm for distributed systems involving heterogeneous devices and requiring real-time communication. However, edge computing is still in its initial stage and there is no consensus on the edge framework and implementation. To the best of our knowledge, no detailed studies have explored the edge-side simulation and modeling. In this paper, we study and design an edge-side simulation framework, which exploits light-weight microservices architecture to build scalable and real-time LVC(Live, Virtual and Constructive) simulations. Specifically, the application model is designed to illustrate how LVC simulation integrates with edge computing and cloud computing. The autonomous negotiation service and time synchronization services are discussed in details. Though it is a preliminary edge computing framework for LVC simulation, no similar research has been conducted for modeling and simulation using edge computing.

关键词： Edge-side simulation microservices LVC simulation IoT

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An Improved Frequency Tracking Algorithm for Frequency Hopping Signals Based on ARMA Model

An Improved Frequency Tracking Algorithm for Frequency Hoppi...

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IEEE International Conference on Signal Processing, Communications and Computing

作者： Jing Ma Bin Shi Yifan Wang Xiaochen Guo Science and Technology on Special System Simulation Laboratory Information and Communication Engineering Department Harbin Engineering University

ISBN: (纸本)9781728117096

Aiming at the real-time processing problem of frequency hopping signals, a frequency tracking algorithm based on FFT, multi-channel clustering and the autoregressive moving average (ARMA) model is proposed in this paper. First, the algorithm performs FFT processing on the received signal samples and estimates the number of source signals and carrier frequency by clustering method. Second, estimate the model coefficients to construct the ARMA model. Then, predict the signal and estimate the decision threshold. Finally, the frequency hopping is determined according to the error between the predicted value of the signal sample and the true value. The experimental results show that the improved algorithm has higher frequency estimation accuracy than the traditional ARMA algorithm after receiving enough signal samples and has lower computational complexity than the SBL algorithm.

关键词： Frequency hopping signals Multi-channel clustering Autoregressive moving average model Frequency hopping signal sampling frequency tracking signals algorithms Frequency estimation predicted value Clustering methods Fast Fourier transform

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Lightweight Incremental File Check pointing

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IOP Conference Series: Materials science and Engineering 2020年第3期782卷

作者： Shuangjian Wei Qiurui Chen Beijing Institute of Technology Beijing 100081 China Science and Technology on Special System Simulation Laboratory Beijing Simulation Center Beijing 1000854 China

Checkpoint technology can improve the efficiency of simulation backtracking. Existing check pointing tools are dedicated to solving system fault tolerance and load balancing problems, and have limited support for persistent data. The overhead of setting and restoring checkpoints for persistent data is critical for simulation backtracking. We designed LibIFC to deal with the problem of checkpoint overhead for persistent data in two aspects. Firstly, the incremental method is used to reduce the space cost of the checkpoint; secondly, a two-way recovery method is used to reduce the time cost of checkpoint recovery. The experimental results show that the above two strategies have achieved significant results in terms of space overhead and checkpoint recovery time overhead.

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Design of High-Gain Cavity-Backed Planar Spiral Antenna Based on Arc-Shaped Metasurface

Design of High-Gain Cavity-Backed Planar Spiral Antenna Base...

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International Conference on Microwave and Millimeter Wave technology Proceedings

作者： Jian-yi Chu Lin Peng Jing Ma Bin Shi Yan-ru Hua Zhi-peng Li Xing Jiang Si-min Li Guangxi Key Laboratory of Wireless Wideband Communication and Signal Processing Guilin University of Electronic Technology Guilin Guangxi China Science and Technology on special system simulation laboratory Beijing Simulation Center Beijing China

A high-gain cavity-backed planar spiral antenna based on arc-shaped metasurface (ASM) is proposed and designed. The unidirectional beam of the Archimedean planar spiral antenna (ASA) is achieved by loading the λ/4-distance metal reflector back cavity. A metasurface consisted of arc-shaped unit cells is located at 28mm above the spiral. The simulated results indicate that the impedance bandwidth of the proposed antenna is 4.53-8.29GHz and the axial ratio bandwidth of 3dB is 5.33-8.29GHz. The gain of the cavity-backed planar spiral antenna is increased by dBi in the frequency band 4.5-6.25GHz due to the proposed ASM, and the proposed antenna presents a peak gain of 12.67 dBi at 5.5GHz.

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Design of Dynamically Tunable Broadband Polarization Converter in Terahertz Frequency Based on Graphene Strips

Design of Dynamically Tunable Broadband Polarization Convert...

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International Conference on Microwave and Millimeter Wave technology Proceedings

作者： Tian-Cheng Zheng Lin Peng Xiao Liu Jing Ma Bin Shi Zhi-Hua Zhao Guangxi Key Laboratory of Wireless Wideband Communication and Signal Processing Guilin University of Electronic Technology Guilin Guangxi China Science and Technology on special system simulation laboratory Beijing Simulation Center Beijing China

A dynamically tunable polarization converter has been proposed in this paper, which has a multi-layer structure consisting of an orthogonal cross metallic, graphene strips, spacer substrate and a gold back ground layer. In this paper, the proposed polarization converter can transform the linear polarization incident waves into its cross polarization in reflection mode in terahertz (THz) frequency within an ultra-wideband, and the polarization conversion ratio (PCR) of the proposed structure has over 97% from 4.1 THz to 7.1 THz. Furthermore, by adjusting the chemical potential (or Fermi energy) of the graphene strips, the operating frequency band can be changed dynamically.

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Hadoop perfect file: A fast access container for small files with direct in disc metadata access

arXiv

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arXiv 2019年

作者： Tchaye-Kondi, Jude Zhai, Yanlong Lin, Kwei-Jay Zhu, Liehuang Tao, Wenjun Yang, Kai School of Computer Science Beijing Institute of Technology Beijing100081 China Department of Electrical Engineering and Computer Science University of California IrvineCA92697 United States Science and Technology on Special System Simulation Laboratory Beijing Simulation Center Beijing China

Storing and processing massive small files is one of the major challenges for the Hadoop Distributed File system (HDFS). In order to provide fast data access, the NameNode (NN) in HDFS maintains the metadata of all files in its main-memory. Hadoop performs well with a small number of large files that require relatively little metadata in the NN’s memory. But for a large number of small files, Hadoop has problems such as NN memory overload caused by the huge metadata size of these small files. We present a new type of archive file, Hadoop Perfect File (HPF), to solve HDFS’s small files problem by merging small files into a large file on HDFS. Existing archive files offer limited functionality and have poor performance when accessing a file in the merged file due to the fact that during metadata lookup it is necessary to read and process the entire index file(s). In contrast, HPF file can directly access the metadata of a particular file from its index file without having to process it entirely. The HPF index system uses two hash functions: file’s metadata are distributed through index files by using a dynamic hash function and, for each index file, we build an order preserving perfect hash function that preserves the position of each file’s metadata in the index file. The HPF design will only read the part of the index file that contains the metadata of the searched file during its access. HPF file also supports the file appending functionality after its creation. Our experiments show that HPF can be more than 40% faster file’s access from the original HDFS. If we don’t consider the caching effect, HPF’s file access is around 179% faster than MapFile and 11294% faster than HAR file. If we consider caching effect, HPF is around 35% faster than MapFile and 105% faster than HAR file. Copyright © 2019, The Authors. All rights reserved.

关键词： File organization

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The Comparison of Different Visual Features for Visual Odometry

The Comparison of Different Visual Features for Visual Odome...

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2018 IEEE CSAA Guidance, Navigation and Control Conference, CGNCC 2018

作者： Jiang, Yuehan Wang, Qing Dong, Chaoyang Zhou, Min Zhong, Kewei Beihang University School of Automation Science and Electrical Engineering Beijing100191 China Science and Technology on Special System Simulation Laboratory Beijing Simulation Center Beijing100854 China Shanghai Aerospace Control Technology Institute Shanghai201100 China

ISBN: (纸本)9781538611715

For robots to work effectively, the availability of a map with detailed information surrounding the workspace is an important requirement for indoor and outdoor tasks. This is usually achieved with using visual odometry techniques with feature-based methods. In this paper, we compare the performance of three different feature extraction methods: Scale Invariant Feature Transform (SIFT), Speed Up Robust Features (SURF) and Oriented FAST Rotated BRIEF (ORB). This paper presents experimental results on standard evaluation datasets and all experiments use measurement of the number of image correspondences as well as the ratio of good matched for the evaluation purpose. The results of experiments demonstrate that the performances of three methods in processing time, matching capability and accuracy. SIFT presents its stability in most scenarios although it is very slow. SURF is faster than SIFT and outperform SIFT on some scenarios. ORB is the most efficient feature and shows strong performance. © 2018 IEEE.

关键词： Vision

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Scattering Center Modeling Using Adaptive Segmental Compressive Sampling

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Journal of Beijing Institute of technology 2017年第4期26卷 484-493页

作者： Qifeng Li Kunyi Guo Jiaxin Wang Xinqing Sheng Tianshu Liu Center for Electromagnetic Simulation School of Information and ElectronicsBeijing Institute of Technology Science and Technology on Special System Simulation Laboratory Beijing Simulation Center

In order to deal with aliasing distortions of Doppler frequencies shown in time-frequency representation（ TFR） with aspect undersampling,an approach using adaptive segmental compressive sampling according to the aspect dependencies of the scattering centers is proposed. The random noise problem induced by compressive sampling is solved by employing a series of signal processing techniques of filtering,image transformation and Hough Transform. Three examples are presented to verify the effectiveness of this approach. The comparisons between the built models and the precise scattered fields computed by a well-validated full-wave numerical method are investigated,and the results showgood agreements between each other.

关键词： scattering center undersampling compressive sensing time-frequency representation parameter estimation

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