一种封闭空间自适应有源噪声控制系统优化方法

将遗传算法（GA）引人封闭空间自适应有原噪声控制（AANC）系统优化设计,以解决长期以来缺乏有效的确定封闭空间次级声源和误差传感器最优位置方法的问题。以小阻尼矩形空间为例,进行了计算机仿真。结果证明：此方法对封闭空间AANC系统优化是有效的。     

110kV变压器有源噪声控制系统电声器件布放的优化设计

阐述自由声场中基于多点声源阵的有源噪声控制策略.结合实验测量的某型号110kV变压器噪声数据,运用多声源阵有源控制策略对其低频噪声进行有源控制.通过对仿真结果分析,总结出控制系统中次级源与误差传感器个数、它们的空间排布对控制效果的影响规律.理论上次级源与误差传感器的个数越多,控制效果越好.但过多的次级源与误差传感器必然...     

基于分布参数理论噪声有源控制的研究

基于分布参数控制理论和声学理论，本文清晰地表达了有源消声（ＡＮＣ）所涉及的控制对象、控制系统和性能指标间的关系，指出了控制系统设计所要满足的稳定性条件和消声条件，为ＡＮＣ的进一步研究提供了有效的方法。文中对目标消声处局部区域声场状况，在主次声源、传声器不同位置下进行了仿真计算，弥补了以往未作这方面分析的不足，为有源消声系统的位置布放提供了依据。     

局部工作空间有源降噪系统次级声源与误差传感器布放研究

为有效抑制工作空间的低频噪声,对有源降噪系统次级声源与误差传感器的布放进行研究。以纺织机械-簇绒地毯织机的工作空间为研究对象,对簇绒地毯织机工作空间的噪声进行采集,以目标区域降噪量最大为控制目标,确定目标函数,采用蚁狮算法对有源降噪系统中的次级声源以及误差传感器的位置进行优化,得出最优布放方案,并分别进行单频和实际噪声的仿真分析。结果表明,根据蚁狮算法得到的布放方案在0～500 Hz的频段上平均降噪量为3.17 dB,能够很好抑制簇绒地毯织机工作空间的低频噪声。该结论可为后续簇绒地毯织机工作空间主动噪声控制系统的设计提供参考。     

自适应空间有源消声最佳消声效果的实现

本文针对一个自适应有源消声控制系统以及一个以点声源为次级源的声系统，就如何实现空间最佳消声效果问题进行了讨论，给出了误差传声器的个数及空间位置与空间消声效果之间的关系，提出误差传声器应放置在实现消声后声压的极小方向上。所得结论在实验中得到了证实。     

自由声场自适应有源噪声控制中误差传感器的布放

合理地布放误差传感器可以减小自适应有源噪声控制系统的复杂性，提高降噪量。本文研究了自由声场条件下误差传感器布放与ＡＡＮＣ系统降噪效果的关系，从理论和实验两个方面总结了自由场误差传感器布放规律。     

一种适用浅海声源的多阵列直接定位方法

针对水下传感器网络系统中的声源定位问题,提出了一种适用于浅海声源的多阵列直接定位方法。该方法根据简正波理论建立阵列接收模型,并根据各阵列接收数据建立联合似然代价函数,最后利用遗传算法进行多维搜索,直接获得声源二维位置估计。仿真结果表明,该方法的声源定位误差小于传统的分步定位方法的定位误差,在较高信噪比时的定位误差稳定在50 m内。该方法通过多阵列联合直接得出声源位置估计,避免了传统分步定位方法中二次估计误差的引入,从而提高了声源定位的精度。     

环球实用技术

环球实用技术智能称重传感器美国ＣＡＲＤＩＮＡＬ公司推出ＳＣＤ型智能称重传感器（Ｓｍａｒｔｃｅ！！），采用百分之百的不锈钢结构，弹性体上端设双膜片抵抗侧向载荷，内置微机电路和数字电路，自动补偿非线性和温度误差，内置过压保护板，以应付闪电引起的电瞬变，采...     

EVA-g-NIPAAm中接枝链亲水性对热敏性的影响

采用空气气氛下预辐射接枝的方法，将Ｎ－异丙基丙烯酰胺（ＮＩＰＡＡｍ）和亲水性单体丙烯酰胺（ＡＡｍ）或丙烯酸（ＡＡ）混合接枝于乙烯－乙酸乙烯酯共聚物（ＥＶＡ）上，研究了亲水性单体对接枝反应和接枝产物溶胀性能的影响，并采用了差示扫描量热法（ＤＳＣ）和热机械分析（ＴＭＡ）等热分析手段来表征其热敏性。结果表明，接枝链亲水性提高，其热敏性转变温度ＬＣＳＴ明显提高。     

改进的波束形成算法及其在多声源定位中的应用

为提高多点声源工况的定位精确度及简化设备,对传统波束形成算法进行改进。引入改进扫描中的扫描向量并结合遗传算法对求解域内的非线性方程组进行求解,从而提高定位精度。基于改进算法,在消声室内采用空间星型(Y型)传感器阵列对不同声源进行定位,并将结果与传统算法定位结果进行比较。由比较可见:当多个声源相距较近时,这些源等效于单一点源,两种算法定位结果基本一致;但当声源相互距离增大时,改进算法可以有效提高定位精度,并准确定位多个源的位置。     

基于球杆仪和光栅尺的工作台精度调整

用球杆仪和光栅尺同时测量了两轴联动精密工作台的走圆运动．结果显示,光栅尺的主要误差源是测量噪声和定位误差,球杆仪的主要误差源是定位误差．尽管对于单轴实时位置反馈来说,光栅尺的测量精度已经足够,但是两个方向光栅尺的测量数据不能反映两轴间的相对精度．通过对光栅尺和球杆仪测量的工作台走圆运动测量数据的分析,建立了测量系统的数学模型,在此基础上解耦并识别出了球杆仪和光栅尺的定位误差．提出了根据光栅尺倾角误差实现工作台精度调整的策略．     

Propagation model and error analysis of an E-field sensor based on pockels effect and waveguide

Electric field measurement sensors based on the crystal Pockels effect are widely used. Currently, the development aims for electric field sensors are mainly focused on miniaturizing and integrating the sensor structure and improving measurement sensitivity and precision. The goal of this study was to analyse the sources of error in Pockels effect electric field measurement sensors, consider the mutual influence and accumulation effect of the various error factors, and establish a basic mathematical model of the measurement system with error components. Calculation and analysis were used to classify the function and change trend of several main errors, providing reference data for the structure design and error compensation of the sensor. The results show that the polarizing angle and the analyser angle have the same influence on assembly error. The inherent error is positively related to the electric field intensity. The periodic accumulation characteristic error under large electric field is also discussed. In order to avoid this error under an intense electric field, a suitable test electric field range was determined.     

分布声源的有源消声理论研究

本文从理论上讨论了次级声源为点源时的空间有源消声特点,以远场声压为零为出发点,导出了初级源为分布声源时计算次级声源复强度的表示式。分析表明空间声压为零条件与系统辐射功率最小条件是一致的。最后本文计算了几种典型初级声源时次级源强度,所得结果利用Nelson 理论进行了验证。     

Genetic algorithm based optimal placement of PIR sensors for human motion localization

This paper studies the optimal placement of pyroelectric infrared (PIR) sensors in developing the infrared motion sensing system for human motion localization. In particular, we explore the use of genetic algorithm (GA) in optimizing both the deployment and the modulated field of view (FOV) of the PIR sensors for improving the localization performance. Two criteria, the average and maximum localization errors, are used to evaluate the localization performance. In addition, the numerical analysis is presented to offer a guidance on the searching spaces of the design parameters in implementing GA optimization. The proposed GA-based design approach is validated by means of both simulation and experimental studies in the context of human-following mobile robots.     

Iterative optimization for joint design of source and channel codes using genetic algorithms

Abstract

This paper presents a novel algorithm for the joint design of source and channel codes. In the algorithm, channel‐optimized vector quantization (COVQ) and rate‐punctured convolutional coding (RCPC) are used for design of the source code and the channel code, respectively. We employ the genetic algorithm (GA) to prevent the design of COVQ from falling into a poor local optimum. We also adopt the GA to reduce the computational time needed for realizing the unequal error protection scheme best matched to the COVQ. Both the GA‐based source coding and channel coding scheme are then iteratively combined to achieve a near global optimal solution for the joint design. Numerical results show that the algorithm can be an effective alternative for applications where high rate‐distortion performance and low computational complexity are desired.     

Comparison of model order reduction methods for optimal sensor placement for thermo-elastic models*

In this article an optimal sensor placement problem for a thermo-elastic solid body model is considered. Temperature sensors are placed in a near-optimal way so that their measurements allow an accurate prediction of the thermally induced displacement of a point of interest (POI). Low-dimensional approximations of the transient thermal field are used which allows for efficient calculations. Four model order reduction (MOR) methods are applied and subsequently compared with respect to the accuracy of the estimated POI displacement and the location of the sensors obtained.     

A review of cryogenic thermometry and common temperature sensors

This paper reviews cryogenic temperature sensors and gives an overview of cryogenic thermometry over the range 20 mK to 100 K. It begins with a brief overview of primary thermometry and methods used to realize and disseminate the International Temperature Scale of 1990, ITS-90. A short review of secondary thermometry is presented, focusing the discussion on commonly available sensors. The integration of temperature sensor to a total measurement system is discussed as well as potential sources of measurement error