压缩感知算法在阵列测向中的相干信号分辨

现有算法在进行信号重建时,需要原始信号的稀疏信息来控制初始原子集的大小和算法迭代的最大次数,这削弱了重建精度,增加了计算复杂度,限制了其实际应用能力。为了克服这个问题,提出了基于正交匹配追踪算法的改进算法。该算法将阵元个数作为假设稀疏度,在稀疏度未知的初始阶段扩展初始原子集。最后通过对测量信号的幅度进行阈值过滤以实现信号的分辨和信源数的估计。为解决测向人员面对监测软件所指示的多个信号示向度中,无法分辨哪些指示方向是同一个信号源所产生的折反射信号的问题,首次提出了基于压缩感知算法的相干关系分析和相干信号分辨的模型。实测数据结果表明,该算法在不同环境下可以清晰分辨相干信号,并且能够适应多种实验平台。     

医学图像数据压缩中的机器学习方法

在医学研究中会产生大量需要储存、传输的图像数据,如计算机断层扫描(CT)等.医院要处理海量患者的所有数据相当困难,必须对这些数据进行压缩.随着人工智能技术的发展,应用机器学习的医学图像数据压缩方法成为新的研究热点.文中首先总结了传统医学图像数据压缩方法;然后基于机器学习的医学图像数据压缩方法,对各类方法针对脑部CT、肺部CT等不同医学图像的压缩效果进行对比,并对这些方法在压缩率、算法复杂度、重构质量等方面的优缺点进行系统的总结,指出机器学习和感兴趣区域结合的方法可以在享受有损压缩带来的高压缩率的同时保留重要区域的特征信息,比其他压缩方法更贴合医学数据的压缩要求;最后展望了该领域的未来方向和挑战.     

基于大数据的成绩可视化分析与研究

从海量的大数据中挖掘出潜在的有价值的信息并进行可视化分析已成为研究的热点.文章根据成绩大数据,从班级、课程等多维度进行成绩可视化分析,为教学管理者提供学生学习情况分析服务.经研究发现,成绩的可视化分析不仅能为管理者提供精准的教学支持,还能使学生及时发现学业问题.     

一种高压开关综合数据采集与监测系统设计

高压开关是电力系统中实现电路分合控制的重要电力装备,对高压开关进行在线监测可以实时监测其运行状态,进而为故障诊断、预测、电寿命、绝缘等分析提供数据来源,可以提高高压开关整体运行可靠性和减少故障时间;数据采集与监测装置是实现这种在线监测功能的核心装置,基于FPGA+STM32双处理器架构的高速数据采集系统,利用FPGA灵活的可编程特性实现高速并行数据采集,利用STM32微控制器强大的处理能力和丰富的外围接口实现数据处理、控制和传输,FPGA和STM32之间通过FSMC接口实现快速数据交换;装置采集了高压开关设备多个传感器数据,通过工业串口液晶屏作为本地人机交互界面,同时以太网接口通过TCP协议上传数据给远端,实现了高压开关运行状态的在线监测。     

车载超短波电台维修检测系统的设计与实现

针对某新型车载超短波电台原理结构复杂、自检虚警率高、故障定位困难等问题,综合采用嵌入式技术、数据库软件、电路智能检测等技术,以车载超短波电台维修检测主机+模件测试夹具的架构构建硬件平台,研制开发车载超短波电台维修检测系统;该系统能够实现对车载超短波电台整机频率误差、输出功率、接收灵敏度等参数及电台内部模件性能指标的自动化测试,测试结果与标准特征值比对,实现电台整机技术状态评估和模件级故障定位,实现电台维修信息的实时存储与查询,从而解决陆军部队车载超短波电台维修检测手段不足、维修保障困难等实际问题。     

Haptic teleoperation of a multirotor aerial robot using path planning with human intention estimation

Classical haptic teleoperation systems heavily rely on operators’ intelligence and efforts in aerial robot navigation tasks, thereby posing significantly users’ workloads. In this paper, a novel shared control scheme is presented facilitating a multirotor aerial robot haptic teleoperation system that exhibits autonomous navigation capability. A hidden Markov model filter is proposed to identify the intention state of operator based on human inputs from haptic master device, which is subsequently adopted to derive goal position for a heuristic sampling based local path planner. The human inputs are considered as commanded velocity for a trajectory servo controller to drive the robot along the planned path. In addition, vehicle velocity is perceived by the user via haptic feedback on master device to enhance situation awareness and navigation safety of the user. An experimental study was conducted in a simulated and a physical environment, and the results verify the effectiveness of the novel scheme in safe navigation of aerial robots. A user study was carried out between a classical haptic teleoperation system and the proposed approach in the identical simulated complex environment. The flight data and task load index (TLX) are acquired and analyzed. Compared with the conventional haptic teleoperation scheme, the proposed scheme exhibits superior performance in safe and fast navigation of the multirotor vehicle, and is also of low task and cognitive loads.

     

存在高渗透区的黏土心墙土石坝渗流稳定性分析

黏土心墙土石坝是重要的挡水建筑物,心墙的低渗透性可以大幅降低坝体水力梯度,减少坝体发生渗透破坏的风险。然而心墙的质量问题（如局部高渗透区）会影响坝体的渗透稳定性,甚至酿成管涌溃坝等严重后果。以瀑布沟心墙土石坝为原型开展坝体渗流大型水槽模型试验,并结合有限元数值模拟方法研究高渗透区对坝体内部渗流场和渗流稳定性的影响。试验表明高渗透区域将改变心墙的渗流场,成为优势渗流通道,导致高渗透区域附近孔压值大幅上升,同时高渗透区域的存在将显著提升坝体渗漏速率。试验与模拟结果一致表明,随着高渗透区域逐步上移,高渗透区所在位置处的孔隙水压力增大,坝体渗漏量减小。高渗透区和心墙的渗透系数增加都会使心墙孔压值和渗漏量增加;随着高渗透区的渗透系数的增大,心墙坝渗流稳定性系数降低,导致坝体稳定性下降;随着心墙渗透系数的增大,高渗透区水力梯度略微减小,但心墙整体临界水力梯度下降,坝体稳定性降低。所得结论可为基于监测数据反演分析心墙的质量问题和评估坝体的安全性能提供依据。     

Dynamic responses of K-type and inverted-K-type jacket support structures for offshore wind-turbines

Journal of Central South University - The jacket structure has become more popular as the offshore wind-turbine support structure. K-type and inverted-K-type jacket support structures have superior...     

600 mesh silicon carbide corona protection varnish with epoxy/OMMT nano-composite adhesive

A new corona protection varnish was prepared by using epoxy/montmorillonite nano-composite and pure epoxy resin as adhesives respectively. The adhesive with different amounts of organic montmorillonite (OMMT) was mixed with 1200 mesh silicon carbide (SiC) by different weight ratios. The surface states of the varnishes with various adhesives were observed by powerful optical microscope. Some properties of the varnishes were analyzed during the enduring time under 5kV/cm DC, such as the relation of change in nonlinear coefficient, natural surface resistivity, and surface temperature variation. The results showed that the amounts of OMMT had little effect on the natural surface resistance of the varnish but had important influence on the nonlinear property of the varnish. When the range of the OMMT content was 2wt% to 6wt%, the nonlinear coefficient of all materials with epoxy/OMMT nano-composite adhesive was higher than that with pure epoxy resin adhesive. The surface temperature of the varnish with epoxy/OMMT nanocomposite adhesive was all lower than that with the pure epoxy resin adhesive under high electrical field strength.     

云存储中加密数据的自适应重复删除方法

为了保护个人隐私,用户倾向于在数据上传至云服务器之前将其加密. 相同的明文数据被加密成不同密文数据,使云服务器无法识别出重复的加密数据. 现存的解决方案多数倚赖可信第三方,且没有划分数据流行度,导致安全性与执行效率较低. 提出一种无需可信第三方的自适应重复删除方法.利用完美散列函数检查数据的流行度,使用口令认证密钥交换协议与同态加密安全传递数据的加密密钥,在保证用户数据隐私的前提下进行安全的重复数据删除. 与现有其它方案相比,安全性与实用性更强. 实验和仿真证明了方案的高效性.