基于EMD和互信息熵的微震信号自适应去噪

针对强干扰背景下的微震信号提取,提出一种基于经验模态分解（Empirical Mode Decomposition,EMD）和互信息熵的自适应提取算法。通过EMD对微震信号进行分解,得到高频和低频两部分信号,并对分解得到的各阶固有模态分量求出能量和能量熵值。根据互信息准则,通过依次计算相邻分量能量熵之间的互信息值来区分高频和低频信号。将经过自适应阈值滤波后的高频信号和低频信号一起进行信号重构,得到新的微震信号。仿真结果表明,在对微震信号去噪时,该方法可以有效地去除噪声信号,信噪比均提升了10 dB以上。工程上的微震信号通过该方法处理后,也取得了较好的效果。     

无线无源声表面波传感器研究进展

声表面波（SAW）传感器是一种无线无源传感器,在无源传感、适应恶劣环境等许多方面具有普通传感器不能实现的优点.阐述了声表面波器件的原理和结构特点,并对射频信号收发、信息处理等关键技术进行详细论述,综述了近些年国内外的相关研究现状,并进行了总结与展望.     

基于无线疲劳监测系统的铝合金材料疲劳损伤研究

铝合金材料具有重量轻、强度高等特点,是国民经济发展的重要基础材料,在诸多领域(如飞行器设计与制造、建筑装饰等)中占有十分重要的地位。然而,其抗疲劳性能较差,在交变荷载作用下容易产生疲劳裂纹和发生疲劳破坏。提出了一种基于无线疲劳监测系统的铝合金材料疲劳损伤研究方法,实时监测了铝合金构件的疲劳应变,并实时分析了构件的疲劳损伤状况,为研究铝合金材料的疲劳性能提供了可借鉴性的方法。     

不同频率激励信号下土壤水分传感器性能试验

激励信号频率是影响高频电容式土壤水分传感器性能的重要因素。利用去离子水和2—异丙氧基乙醇(2—isoproxyethanol)或二氧六环(dioxane)2种溶液混合,配制了一系列等效土壤体积含水率为0.9%~51.8%的待测介电溶液来替代土样。从与土壤含水率的函数关系、温度变异性2个方面,分别对激励信号频率为40,50,60,70,80,90,100 MHz的7种土壤水分传感器进行了性能测试与分析。结果表明:7种频率的传感器的输出电压均与土壤体积含水率呈线性负相关,其相关系数R2均大于0.94;激励信号频率不影响传感器输出电压的温度变异性,温差是影响温度变异性的主要因素,其最大变异率均小于4%。试验结果可为设计高频电容式土壤水分传感器时选择激励信号频率提供依据。     

OpenMDSP: Extending OpenMP to Program Multi-Core DSPs

Abstract Multi-core digital signal processors （DSPs） are widely used in wireless telecommunication, core network transcoding, industrial control, and audio/video processing technologies, among others. In comparison with general-purpose multi-processors, multi-core DSPs normally have a more complex memory hierarchy, such as on-chip core-local memory and non-cache-coherent shared memory. As a result, efficient multi-core DSP applications are very difficult to write. The current approach used to program multi-core DSPs is based on proprietary vendor software development kits （SDKs）, which only provide low-level, non-portable primitives. While it is acceptable to write coarse-grained task-level parallel code with these SDKs, writing fine-grained data parallel code with SDKs is a very tedious and error-prone approach. We believe that it is desirable to possess a high-level and portable parallel programming model for multi-core DSPs. In this paper, we propose OpenMDSP, an extension of OpenMP designed for multi-core DSPs. The goal of OpenMDSP is to fill the gap between the OpenMP memory model and the memory hierarchy of multi-core DSPs. We propose three classes of directives in OpenMDSP, including 1） data placement directives that allow programmers to control the placement of global variables conveniently, 2） distributed array directives that divide a whole array into sections and promote the sections into core-local memory to improve performance, and 3） stream access directives that promote big arrays into core-local memory section by section during parallel loop processing while hiding the latency of data movement by the direct memory access （DMA） of a DSP. We implement the compiler and runtime system for OpenMDSP on PreeScale MSC8156. The benchmarking results show that seven of nine benchmarks achieve a speedup of more than a factor of 5 when using six threads.     

一种准Z-源DC-DC变换器的建模与控制

分析了准Z-源DC-DC变换器在稳态时的工作原理,根据状态空间平均法建立了准Z-源DC-DC网络在电流连续工作模式下(CCM)的交流小信号模型,并对模型进行分析,获得控制至输出的传递函数,实现了输出电压闭环控制。最后建立了实验样机,进行了实验验证。     

网络化雷达协同抗欺骗式干扰技术研究进展

网络化雷达在战场上可以构成全方位、立体化、多层次的战斗体系,因 此对欺骗式干扰对抗具有很大的优越性。本文首先简要介绍了网络化雷达概念,并分析了其 抗干扰优势。根据网络化雷达融合结构不同,将现有协同抗干扰方法分为数据级融合抗欺骗 式干扰和信号级融合抗欺骗式干扰两大类,其中,数据级融合方法进一步分类为点迹关联和 航迹关联两类。本文对各类方法进行了详细介绍,在此基础上,比较分析了数据级融合和信 号级融合两类方法的抗干扰性能及算法复杂度,为抗干扰措施的选择提供依据。最后,针对 现有方法中存在的问题,对网络化雷达协同抗欺骗式干扰的发展趋势进行展望,指出下一步 的研究方向。     

基于光纤布拉格光栅的微波光子信号处理

由于有效利用了光子技术的优点,微波光子技术克服了传统微波系统中的一些瓶颈,从而提高已有系统性能,甚至开发出了全新的系统应用。很多光子器件已经被用在微波光子系统中,光纤布拉格光栅（Fiber Bragg grating, FBG）就是其中一种非常重要的全光纤器件。由于具有灵活的频谱响应特性、损耗低、质量轻、结构紧凑、以及与其他光纤器件耦合性好等独特的优势,光纤布拉格光栅已经成为了微波光子信号处理系统中的关键组件之一。本文主要介绍了近年来光纤布拉格光栅在微波光子信号处理应用中的最新进展,重点讨论的主要应用包括微波光子滤波器,微波任意波形产生,微波频谱感知以及光纤光栅传感器实时解调。最后,本文还讨论了在微波光子系统中应用光纤布拉格光栅的局限性及可能的解决方案。     

Gas-Chromatographic Analyses of the Subcaudal Gland Secretion of the European Badger (Meles meles) Part I: Chemical Differences Related to Individual Parameters

In many species, chemical signals are important in the context of intraspecific communication. European badgers (Meles meles) use the secretion of their subcaudal gland to mark both the environment and conspecifics. In this paper, we investigated the chemical composition of subcaudal gland secretions and how it varies among individuals according to group membership, season, sex, age, body condition, and reproductive status. We analyzed 66 samples by gas chromatography using a mass-spectrometer as detector. We found 110 different components, of which 21 were present in every profile. The chemical composition of the secretions proved to be highly individual-specific, but no single peak was found to be typical for one of the investigated categories (season, sex, etc.). Analyses of the relative area (% area) that every peak contributed to the overall profile area showed that, in general, group members have more similar profiles than do badgers from different groups. Composition varied over seasons and between sexes and was influenced by age, body condition, and reproductive status. We, therefore, conclude that the secretion not only encodes group membership and individuality as previously assumed, but might also convey information about fitness-related parameters.