毫米波安检成像雷达设计

针对实际应用的安检技术的局限性,本文介绍一种基于FMCW的体制的安检成像雷达设计。雷达采用合成孔径成像算法对待检人员身上的隐匿目标进行探测,使用二维、三维仿真目标和Radarsat—I雷达数据对雷达系统和成像算法进行检验,计算结果证明了系统设计和成像方法的有效性。     

谈谈我校现代电工电子实验室的教学与开放

我校自动化学院电工电子实验中心相继建成了“ＥＤＡ开放实验室”,“ＣＡＤ／ＣＡＩ实验室”和“ＰＬＣ实验室”三个现代电工技术实验室,并于１９９７年相继投入教学与开放,本文结合我们参与现代电工技术实验室教学与开放的实践,谈谈我们的感受与体会．     

国家级弱磁实验室高精度中央空调设计

弱磁计量实验室对磁环境、温度控制精度均有严格要求.普通恒温恒湿空调器虽然能达到温度控制精度要求,但由于含铁磁物质,不能在该环境下使用;常规中央空调系统虽然可以满足磁环境要求,但难以满足温度波动小于0.2℃/h的温控精度要求.本项目设计采用中央空调加分区控温的方式较好地解决了该难题,设计中采用高效能热隔离、小温差送风、孔...     

Investigation of candidate VRM topologies for futuremicroprocessors

By reducing the power supply voltage, faster, lower power consumption, and high integration density data processing systems can be achieved. The current generation high-speed complementary metal-oxide-semiconductor (CMOS) processors (e.g., Alpha, Pentium, Power PC) are operating at above 300 MHz with 2.5 to 3.3 V output range. Future processors will be designed in the 1.1-1.8 V range, to further enhance their speed-power performance. These new generation microprocessors will present very dynamic loads with high current slew rates during transient. As a result, they will require a special power supply, voltage regulator module (VRM), to provide well-regulated voltage. The VRMs should have high power densities, high efficiencies, and good transient performance. In this paper, the critical technical issues to achieve this target for future generation microprocessors are addressed. A VRM candidate topology, interleaved quasisquare-wave (QSW), is proposed. The design, simulation and experimental results are presented     

An Artificial Skyrmion Platform with Robust Tunability in Synthetic Antiferromagnetic Multilayers

Magnetic skyrmions are topologically nontrivial spin structures, and their existence in ferromagnetically coupled multilayers has been widely reported with a disordered arrangement. Here, a nucleation scenario of ordered skyrmions in nanostructured synthetic antiferromagnetic (SAF) multilayers is proposed and experimentally demonstrated using direct magnetization imaging, indirect magnetometer and magnetoresistance measurement, and micromagnetic simulation. Instead of relying on Dzyaloshinskii–Moriya interaction, the antiferromagnetic interlayer exchange coupling in the SAF multilayers fulfills the role of nucleation and stabilization of skyrmions. The robustness of the proposed skyrmion nucleation scenario is examined against temperature from 4.5 to 300 K and device size from 400 to 1200 nm. Interestingly, these synthetic skyrmions still behave well with a size less than 100 nm. The higher stability than generic magnetic domains can be attributed to topological protection. The results thus provide an artificial skyrmion platform to meet the functional needs of high density and designable arrangement in magnonic and spintronic applications.     

High‐Performance Manganese Hexacyanoferrate with Cubic Structure as Superior Cathode Material for Sodium‐Ion Batteries

Sodium manganese hexacyanoferrate (Na_xMnFe(CN)₆) is one of the most promising cathode materials for sodium‐ion batteries (SIBs) due to the high voltage and low cost. However, its cycling performance is limited by the multiple phase transitions during Na⁺ insertion/extraction. In this work, a facile strategy is developed to synthesize cubic and monoclinic structured Na_xMnFe(CN)₆, and their structure evolutions are investigated through in situ X‐ray diffraction (XRD), ex situ Raman, and X‐ray photoelectron spectroscopy (XPS) characterizations. It is revealed that the monoclinic phase undergoes undesirable multiple two‐phase reactions (monoclinic ? cubic ? tetragonal) due to the large lattice distortions caused by the Jahn–Teller effects of Mn³⁺, resulting in poor cycling performances with 38% capacity retention. The cubic Na_xMnFe(CN)₆ with high structural symmetry maintains the structural stability during the repeated Na⁺ insertion/extraction process, demonstrating impressive electrochemical performances with specific capacity of ≈120 mAh g^?1 at 3.5 V (vs Na/Na⁺), capacity retention of ≈70% over 500 cycles at 200 mA g^?1. In addition, the TiO₂//C‐MnHCF full battery is fabricated with an energy density of 111 Wh kg^?1, suggesting the great potential of cubic Na_xMnFe(CN)₆ for practical energy storage applications.     

诊断权衡优化测试性分析技术

现今对于电子设备进行故障诊断以及后续PHM的需求越来越多,本文结合测试性分析的流程,提出了一种面向诊断的测试性分析方法,并使用开发的软件对某型号的发电机进行测试性建模与分析,按照给出的诊断策略进行测试可以取得比较好的效果。     

Distributed machine learning load balancing strategy in cloud computing services

Wireless Networks - Mobile service computing is a new cloud computing model that provides various cloud services for mobile intelligent terminal users through mobile internet access. The quality of...     

基于MNMP的ScanSAR并行成像系统设计

该文对星载ScanSAR成像并行处理进行了详细的研究。首先,针对ScanSAR成像机制的特殊性,给出了基于传统主-从模式的并行实现流程。根据主-从模式的不足,该文提出了一种基于多节点-多进程的异步并行模式的星载ScanSAR并行处理的技术。实验结果表明,相对于传统的并行处理方法,该文所采用方法的成像时间得到了较好的改善,具有一定的优越性。     

Tsallis Entropy Based q-Gaussian Density Model and Its Application in Measurement Accuracy Improvement

The central limit theorem guarantees the distribution of the measurand is Gaussian when the number of repeated measurement is infinity, but in many practical cases, the number of measurement times is limited to a given number. To overcome this contradiction, this paper firstly carries out the maximum likelihood estimation for parameter q in q-Gaussian density model developed under the maximum Tsallis entropy principle. Then the q-Gaussian probability density function is used in the particle filter to estimate and measure the nonlinear system. The estimated parameter q is related to the ratio between the measurement variance and the given variance, which indicates that the measurement accuracy cannot be improved if we only increase the repeated measurement times. Via using the proposed q-Gaussian density model, the measurement error (the average mean square error) of the estimation results can be reduced to a considerable level where the number of repeated measurement is limited. The experimental example is given to verify the proposed model and the measurement results prove the correctness and effectiveness of it.