基于小波分析的谐波在线监测系统

针对传统谐波在线监测系统存的结果不准确,无法描述谐波动态变化特点,设计了基于小波分析的谐波在线监测系统。首先设计了谐波在线监测系统的硬件模块,然后谐波在线监测系统的软件模块,依据小波变换分析谐波信号特征,得到的谐波变化率,从而谐波在线监测系统的监测结果,最后采用具体实验进行了谐波在线监测系统性能的仿真实验,由实验结果可知,该系统的谐波监测精度高,可以有效检测各种谐波分量,保证电力系统稳定运行。     

基于ARM+FPGA的电压监测仪现场校验装置设计与实现

针对电压监测仪因受器件老化及现场环境影响等导致测量准确度降低和现场校验困难等问题,提出了一种基于ARM+FPGA的电压监测仪现场校验设计方案。介绍了校验系统的校验原理及指标,并给出了校验系统的组成及设计原理框图;详细阐述了ARM+FPGA主控模块、幅值调整电路、滤波电路、功率放大电路和通信电路等硬件模块设计。考虑到日趋严重的电网谐波污染,引入鲁棒锁相环实现谐波电压检测以提高监测精度。给出校验系统的软件设计流程,并实现电压监测及误差校验等功能。在无谐波和有谐波环境下进行了系统准确度和长时间稳定度测试。实验结果表明,该校验装置能产生精度为0.05级的标准电压源,以满足校验和长时间工作稳定性要求,有效解决了电压监测仪现场校验难题。     

具有间谐波监测功能的电压监测仪的设计与实现

电网中电压谐波、间谐波的监测是提高电网电能质量的主要手段,针对国内电网中电压谐波、间谐波问题的现状,设计了一种具有谐波、间谐波监测功能的电压监测仪。该监测仪可以实现电网谐波、间谐波的实时监测,并上传数据。文章给出了电压监测仪的软硬件设计方案,并进行了详细论述。     

基于改进FFT变换的地铁电网谐波监测系统虚拟仪器化设计

针对地铁电网谐波具有频率波动及半波对称的特性,以及传统硬件检测方法功能单一、灵活性差等缺点,文中提出了一种改进FFT算法,并在该算法基础上设计并开发了基于虚拟仪器的地铁电网谐波监测系统.该系统硬件采用PC-DAQ结构方案,在一定硬件设备的基础上,增加虚拟仪器开发平台.系统软件采用LabVIEW2009,运用LabVIEW强大的函数库实现数据采集、频率跟踪及谐波分析、数据动态显示等多种功能.改进FFT算法在MATLAB中仿真表明,该算法是传统FFT运算量的一半,提高了运算速度;软件测试表明,该系统能够实现预期功能,并具有检测精度高、实时性及扩展性好等优点.[1-2]     

LPC210x微控制器在电压电流谐波监测仪中的应用

本文讨论了一种三相电压电流谐波监测仪，它能够完成电网谐波的实时监测和长时间的统计记录．并具有多种通信方式上传数据。文中介绍了仪表的系统结构和工作原理．并重点讨论了以LPC210x微处理器为核心的监测仪表的硬件电路和仪表软件设计。     

基于TDLAS技术的N_2O气体检测系统设计

基于红外光谱吸收及谐波检测原理,讨论了谐波信号和气体浓度关系,搭建了基于可调谐激光吸收光谱技术的气体检测系统。该系统采用低频锯齿波和高频正弦波联合调制激光器,并由锁相放大电路提取一次谐波和二次谐波信号幅值,以STM32F103VB控制器为核心,进行数据处理与数据上传,实现对0~0.1%浓度范围氧化亚氮(N_2O)气体实时测量。首先,介绍了系统的总体设计与核心结构,包括系统的硬件结构与软件结构;并进行了系统的标定和性能测试,结果表明二次谐波和一次谐波信号幅值比与浓度具有良好的线性关系,检测精度可达20×10~(-6),满足对N_2O气体实时监测的需求。     

有源电力滤波器的故障诊断与监测系统设计

针对有源电力滤波器(APF)主电路中的IGBT及其驱动器容易引发开路故障,以及如何利用虚拟仪器技术取代传统的电能质量分析装置对APF进行实时监测等问题,通过对APF中IGBT的开路故障进行分析,设计了其相应的故障诊断硬件电路,同时设计了监控系统中的电网电流信号、APF运行温度采样信号的硬件电路,并分析说明了电路工作原理。设计了一种基于Lab VIEW软件的实时监测系统,通过将采样数据发送到该监测系统,实现了利用上位机对APF运行的实时监测功能。最后进行了对电网电压、谐波电流等信号的实时采样,以及对IGBT开路故障的模拟测试。实验及研究结果表明,该系统能够实现对APF的运行状态进行实时监测,同时能够实现IGBT及其驱动器的故障诊断功能,系统故障诊断精确性高、响应迅速。     

基于MSP430的硬件可控滤波电路设计

针对采用软件FFT算法实现的谐波检测占用CPU内存空间大、容易影响系统实时性的问题,提出了基于BPF硬件电路谐波检测的方法。根据实际应用中对定性分析和实时性的要求,对所需要的有源带通滤波器(BPF)和控制电路进行了反复测试,实现了对输入信号中部分奇次谐波的可控检测,提高了检测速度,保证了系统的稳定工作。     

基于ARM和ATT7022C的电能质量监测终端的设计

本文以ARM STM32F103VE6和电表芯片ATT7022C为主构建了电能质量监测终端,利用电表芯片ATT7022C实现对电网电压、电流、频率、功率因素等诸多参数的采样,以ARMSTM32F103VE6芯片做CPU对采样到的数据进行频率准同步转换和FFT计算实现对谐波的测量,该装置可以实现对公用配电网的电压、电流、有功、无功、谐波等参数的精确测量,为公用配电网进行能源监测、无功补偿和谐波治理提供了有效的在线监测手段.     

基于ZigBee和LabVIEW的矿山电力谐波在线监测系统设计

针对传统矿山电力谐波监测系统的不足,设计了基于ZigBee无线传感器网络和LabVIEW虚拟仪器的有色金属矿山电力谐波在线监测系统。系统利用安装于矿山供配电系统的ZigBee节点采集关键点谐波数据,监测信息通过工业以太网传送至监控主机,主机的LabVIEW软件实现数据存储与处理,并为监控人员提供供电系统电力谐波实时信息。现场测试结果表明系统运行稳定,具有较好的实用价值与推广价值。     

Minimal Realization of Linear Graph Models for Multi-physics Systems

An engineering system may consist of several different types of components,belonging to such physical"domains"as mechanical,electrical,fluid,and thermal.It is t...     

INTEGRAL EQUATION METHOD＇S APPLICATION IN HOLE-EDGE STRESS OF COMPOSITE MATERIAL PLATE WITH DIFFERENT SHAPED HOLES

The strength of composite plate with different hole-shapes is always one of the most important but complicated issues in the application of the composite material. The holes will lead to mutations and discontinuity to the structure. So the hole-edge stress concentration is always a serious phenomenon. And the phenomenon makes the structure strength decrease very quickly to form dangerous weak points. Most partial damage begins from these weak points. According to the complex variable functions theory, the accurate boundary condition of composite plate with different hole-shapes is founded by conformal mapping method to settle the boundary condition problem of complex hole-shapes. Composite plate with commonly hole-shapes in engineering is studied by several complex variable stress fimction. The boundary integral equations are founded based on exact boundary conditions. Then the exact hole-edge stress analytic solution of composite plate with rectangle holes and wing manholes is resolved. Both of offset axis loadings and its influences on the stress concentration coefficient of the hole-edge are discussed. And comparisons of different loads along various offset axis on the hole-edge stress distribution of orthotropic plate with rectangle hole or wing manhole are made. It can be concluded that hole-edge with continuous variable curvatures might help to decrease the stress concentration coefficient; and smaller angle of outer load and fiber can decrease the stress peak value.     

Non-monotonic material contrast in scanning ion and scanning electron images

30 keV Ga⁺ focused ion beam induced secondary electron (iSE) imaging was used to determine the relative contrast between several materials. The iSE signal compared from C, Si, Al, Ti, Cr, Ni, Cu, Mo, Ag, and W metal layers does not decrease with an increase in target atomic number Z₂, and shows a non-monotonic relationship between contrast and Z₂. The non-monotonic relationship is attributed to periodic fluctuations of the stopping power and sputter yield inherent to the ion–solid interactions. In addition, material contrast from electron-induced secondary electron (eSE) and backscattered electron (BSE) images using scanning electron microscopy (SEM) also shows non-monotonic contrast as a function of Z₂, following the periodic behavior of the stopping power for electron–solid interactions. A comparison of the iSE and eSE results shows similar relative contrast between the metal layers, and not complementary contrast as conventionally understood. These similarities in the contrast behavior can be attributed to similarities in the periodic and non-monotonic function defined by incident particle–solid interaction theory.     

Application of Feature Extraction through Convolution Neural Networks and SVM Classifier for Robust Grading of Apples

This paper proposes a novel grading method of apples,in an automated grading device that uses convolutional neural networks to extract the size,color,texture,an...     

分布动态载荷识别的抗噪处理

针对正交多项式频域法在用多种响应对矩形薄板进行载荷识别中抗噪性较差的问题,综合运用平均法、矩阵预处理和奇异值截断法等方法对之进行改善,并引入空间映射的思想,将该方法的应用范围拓展为复杂的模型.利用仿真算例,证实了该方法具有较好的抗噪性.     

基于MELTAC-N平台的核电厂安全级DCS环网研究与测试

针对工程实践中环网通讯相关问题的处理缺乏理论基础及国产化安全级DCS平台的开发缺乏成熟经验借鉴问题,对基于MELTAC-N平台核电厂安全级DCS环网的软硬件实现进行了研究。提出了安全级DCS环网双环网冗余设计、光切换开关设计等硬件设计方法,以及以RPR协议为基础,采用全数据收发策略的软件设计方法。在CPR1000安全级DCS平台上对安全级DCS环网的可靠性及实时性进行了评价,并进行了容错能力、响应时间及响应时间稳定性测试验证实验。结果表明,基于MELTAC-N平台安全级DCS环网软硬件设计具有较好的容错能力及响应时间稳定性。     

Short-Term Relay Quality Prediction Algorithm Based on Long and Short-Term Memory

The fraction defective of semi-finished products is predicted to optimize the process of relay production lines, by which production quality and productivity ar...     

End-to-End Multiview Gesture Recognition for Autonomous Car Parking System

The use of hand gestures can be the most intuitive human-machine interaction medium.The early approaches for hand gesture recognition used device-based methods....     

The laboratory simulation of abrasive wear

Abrasive wear has long been recognised as one of the most potentially serious tribological problems facing the operators of many types of plant and machinery; several industrial surveys have indicated that wear by abrasion can be responsible for more than 50% of unscheduled machine and plant stoppages. Locating the operating point of a tribological contact in an appropriate operational ‚map’︁ can provide a useful guide to the likely nature and origins of the surface degradation experienced in use, though care must be exercised in choosing the most suitable parameters for the axes of the plot. Laboratory testing of materials and simulations of machine contacts are carried out for a number of purposes; at one level for the very practical aims of ranking candidate materials or surface hardening treatments in order of their wear resistance, or in an attempt to predict wear lives under field conditions. More fundamentally, tests may be aimed at elucidating the essential physical mechanisms of surface damage and loss, with the longer term aim of building an analytical and predictive model of the wear process itself. In many cases, component surface damage is brought about by the ingress of hard, particulate matter into machine bearing or sealing clearances. These may be running dry although, more usually, a lubricant or service fluid is present at the interface. A number of standardised wear test geometries and procedures have been established for both two- and three-body wear situations, and these are briefly described. Although abrasive wear is often modelled as following an ‚Archard’︁ equation (i.e. a linear increase in material loss with both load and time, and an inverse dependence on specimen hardness) both industrial experience and laboratory tests of particularly lubricated contacts show that this is not always the case: increasing the hardness differential in an abrasively contaminated lubricated pair may not always reduce the rate of damage to the harder surface.     

Limits of topographic measurement by the scanning tunnelling and atomic force microscopes

Parameters describing the topographic character of a surface (height, surface wavelength, slope and curvature) can be derived from equivalent sinusoidal profiles. The response of a surface-measuring instrument may be modelled in terms of instrument parameters such as stylus radius, and scanning range and resolution. The performance of the instrument may then be mapped as a zone in amplitude-wavelength (AW) space to show the sinusoidal profiles it is capable of measuring. In a first-order analysis the STM and AFM are considered as equivalent to contact-stylus instruments with a notional stylus radius equal to the tip radius plus the gap. Comparisons between different instruments and types of instrument are readily made by mapping in AW space. The error arising from convolution of the sinusoidal profile with that of the finite tip may be quantified and plotted as contours in AW space.