基于光纤法珀传感器的局部放电测试系统

针对油浸变压器中局部放电的测试需求,设计了一套基于光纤法珀传感器的超声波测试系统。该系统采用集成可调谐激光模块作为光源,通过光纤环形器把光源、法珀传感器和光电探测器连接起来。光电探测器的直流输出信号通过MCU的检测,用来调整集成可调谐激光器模块的工作波长和传感器的工作点。对光电探测器输出的交流小信号通过信号调理电路进行放大、滤波得到被测声波的模拟信号。通过对模拟信号进行数据采集、分析和显示,实现对局部放电的监测。     

ACFM检测系统的信号调理电路

根据交流电磁场检测(简称ACFM)的信号特征,设计了一种用于ACFM检测系统的信号调理电路.该电路由低噪声的程控放大、自适应带通滤波、后级可调放大和真有效值转换四部分组成.经试验验证,该信号调理电路适用范围宽、检测精度高、可获得理想的检测信号特征曲线,且工作稳定可靠,可用于高性价比的ACFM检测仪器中.     

润滑油磨粒在线检测系统的设计与实现

设计一套润滑油磨粒在线检测系统,实时检测润滑油液中磨粒的尺寸和浓度信息,可以据此判别故障状态。设计螺管型差动变压器式磨粒检测传感器将油液中铁磁性磨粒经过时产生的电磁扰动转换为对应的电压信号。设计前端模拟信号调理电路对其进行前置放大,带通滤波,真有效值转换和调零放大。设计以STM32F103为处理器平台的数字信号处理电路,对调理后的信号进行模数转换、波形显示等。采用局部加权回归散点平滑算法(LOWESS),进一步抑制、消除信号中的噪声,并通过极值转换得到信号的峰峰值,获取反映磨粒尺寸和浓度的信息。实验结果表明系统能够实时准确地实现检测功能。     

多通道环境下油样检测光谱分析系统的方案研究

对于光谱仪的信号采集系统的两个关键技术指标是微弱光电信号的处理和多通道数据的同步采集和传输。在分析信号采集的工作原理基础上，结合工程应用，研究了用于直读光谱仪的多通道数据采集与处理系统。基于微弱光电信号的特性和系统性能指标的需求，设计了以FPGA为控制核心、信号调理模块增益可控、多通道数据并行采集、实现数据无损传输的系统总体设计方案。设计了实现数据采集系统各功能模块的硬件电路，以及FPGA对系统各个模块的控制逻辑，并完成系统硬件测试和功能测试。测试结果表明本系统能够采集光电倍增管输出的微弱电流信号。     

按摩椅自动称重系统设计

介绍一种自动按摩椅体重测试系统,介绍了系统的硬件设计和程序设计流程,包括称重传感器和信号调理电路子系统。对传感器采集体重的模拟信号进行调理,利用集成A/D进行转换后送入到处理器,再进行数字滤波后传送到操作单元进行显示,操作单元根据体重值进行按摩方式选择和身份识别。该检测方法和电路简单可靠,能广泛应用于体重测试系统中。     

微位移检测系统中精密光电转换电路设计

基于像散原理的光学检测系统,是通过对光路系统聚焦信号的离焦量FES的检测实现微位移的测量.四象限光电探测器作为检测系统的光电转换传感器,需要设计光电探测器电路,实现对FES信号的检测,并由微单片机系统采集处理,通过串口通信传给PC机进行数据存储和被测对象二维图像分析和重建.通过将所设计的电路集成在光学测头装置上进行实验测量,光电转换信号稳定,相对误差小于5%.     

一种压阻式传感器信号调理电路的设计

由于压阻式MEMS传感器输出信号极其微弱,极易受到测试环境的噪声干扰,还需要外接调理电路,为了提升信号的采集精度,提出一种压阻式传感器信号ASIC调理电路的设计方案,实现输出信号的放大、滤波功能。测试结果表明,调理电路可以在10～200倍的范围内调节增益,-0.5 dB截止频率调节范围覆盖0.1～20 kHz;低频范围内,芯片的等效噪声为45 nV/√Hz。将调理电路与传感器相结合,改进的测试系统响应速度快,滤波效果更好,测试精度优于5%,传感器非线性为5.4%。同时,调理电路的大小和体积也很小,功耗低,对后续继续研究传感器测试系统有重要意义。     

具有开放气室的实时红外气体检测系统

介绍了一种具有开放气室的实时红外气体检测系统。系统由Silicon Lab C8051F060单片机控制．选用MFMS红外光源和光电二极管红外探测器，依据相关检波基本原理设计了信号调理电路。对乙醇和甲烷气体的测量实验表明：在16Hz的光源调制频率下，系统具有较高的灵敏度和信噪比。     

基于正交锁相放大器的风洞天平信号检测系统

为了提高六分量天平信号的检测精度和抗干扰能力,设计了一种基于正交锁相放大器的风洞天平信号检测系统,由电桥激励源、正交参考信号源、正交锁相放大器及A/D转换等模块电路组成。设计的正交参考信号源采用数字闭环反馈控制方式,有利于参考信号的实时监测与调整,在实测中有效实现激励信号±2.5V、参考信号为1V条件下幅度波动小于2%,正交锁相放大器用于实现六路电桥输出信号同参考信号的正交检波,并输出双路直流分量,经放大处理后转换为数字信号,由MCU计算得到各路电桥的实际输出信号值。经过测试分析,系统能够较准确地检测天平信号,且电桥检测信号有效分辨率约1μV,最大误差为2μV,准确度优于0.2%,有效验证了系统整体设计参数要求,并在实际测试中具有较大的抗干扰特效。     

光纤光栅微弱信号检测的解调电路

为了在光纤光栅匹配解调系统中实现对光纤光栅微弱信号的检测与处理,在应用微弱光电信号检测原理的基础上设计一种高信噪比、高检测精度的解调电路,该解调电路采用低噪声电路元件参数选取原则和前置放大器设计的一般方法,在雪崩光电二极管与信号数模转换之间采用互阻放大器、巴特沃斯滤波电路和多级放大电路,实现了电路的最佳噪声匹配,有效地抑制了电路的噪声和干扰。该解调电路在光纤光栅匹配解调系统中具有很高的信噪比和测量精度,且具有很好的灵敏度,在测量低频率振动信号试验中具有优异的性能。实验表明:该电路解调系统在25～200 Hz正弦激励振动信号下具有很好的低噪声性能,精确的测试出振动信号,同时该电路所采用的方法与措施对其他测量系统也有借鉴意义。     

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.     

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....     

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。     

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.     

ANGULAR DISTORTION ALLOWABLE VALUE AND ASSESS METHOD OF WELD ON COKE TOWER

A graph as the new engineering method for estimate the safety of bulging deformation of coke tower is proposed. Through stresses analysis of circumferential weld of coke tower and comparing the stresses produced by pressure with heat stress of steady state, residual stress, bending stress produced by both itself weight and wind loads, it showed that the stresses produced by pressure on the angle distortion are the main factor of equivalent stress of the combined stress. After comparing four kinds of stress controlling conditions, the relation to stress with depth of angular distortion, grade of curvature of angular distortion and half of region of angular distortion has been inferred. Graph of deformation allowable value of coke tower for different condition by angular distortion and half of region of angular distortion has been plotted. The five steps for its engineering use have been explained. The lighter the grade of curvature is, the larger of bulge allowance, may be, and the bigger of depth of angular distortion may pose too. For the coke tower with a popular structure of Dg 5 400 mm×28 mm, the result by graph is nearly more than the result of two formulas formed by other research, the error is less than 7.0%. But, the graph can be easily applied to different size of angular distortion.