基于Bayes多传感器数据融合的电路故障诊断

针对电子电路的故障诊断问题,提出一种基于Bayes决策理论的多传感器数据融合解决方法.通过测试电路中被诊断元件温度和节点电压2个物理量,得出Bayes理论中不同传感器对各待诊元件的先验概率,在此基础上,利用Bayes条件概率公式进行两级数据融合,得到各元件关于故障类型的目标概率值,进而根据最大概率值确定故障元件.Bayes多传感器数据融合诊断与单传感器诊断方式相比,大大提高了故障识别准确率,并降低了故障元件不确定的概率.实验结果证明:该方案是一种有效的电路故障诊断方法.     

InSb-In磁阻式角度传感器温度特性研究

研究发现,在磁阻元件构成的角度传感器中,由于生产工艺造成的磁阻元件的不对称性与InSb-In磁阻元件本身的温度特性的综合导致了传感器输出的温漂.本文从该传感器结构与工作原理出发,分析了输出温漂的成因,并针对实际生产的情况,提出了一种简便的补偿方案,给出了相应的计算方法.     

用于地下电缆绝缘状态监测的边缘电场法研究

根据地下电力电缆绝缘状念移动监测对传感器的要求,提出运用边缘电场法进行水树老化检测的方案。针对利用传统叉指型FEF传感器进行水树检测干扰大的问题,设计了新型基于弧形基板的叉指型FEF传感器,采用有限无法建立其数学模型,通过MaXwe1l有限元分析软件仿真比较两种传感器在绝缘层中的电场分布情况,并分析电极叉指宽度以及问距宽度变化对传感器电场穿透效果的影响。仿真证明了该新型传感器对电缆绝缘层穿透能力强于传统FEF传感器,最终确定了新型传感器设计参数的最优值。     

电容传感器测量电路的稳零研究

受到测量电路中元件本身性能、温度和供电电源性能等的影响,采用四相检测测量电路的微电容传感器的输出不可避免地会出现零漂,影响传感器的稳定性.为此,对微电容传感器测量电路的零漂现象进行了研究,给出了稳零方案和电路,并说明了电路中各元件对稳零的影响以及元件的选择和计算方法.     

一体化结构三维加速度传感器的设计

设计了一种基于单惯性质量块的一体化结构三维加速度传感器。采用一种特殊结构的弹性体元件,实现了三维加速度量都利用剪切应变测量。利用有限元工具对传感器静态和动态特性进行了分析,给出了弹性体的应变分布、固有频率等。有限元分析计算和实验结果表明:所设计的传感器在3个正交方向上都有较高的灵敏度,各加速度分量互相干扰小。其交差灵敏度小于6.5%,非线性误差小于2%,固有频率大于1700Hz。     

基于Z元件的数字化智能传感器的设计与实现

根据Z元件的特性,使Z元件与单片机相结合,并用最小二乘法对其输出电压与温度之间仔在非线性关系进行拟合,最终得到了一种集数字信号处理和通讯为一体的数字传感器.实验证明该传感器的性能稳定、信号传输误差小,是具有自整定、自寻址功能的智能传感器.     

GYG-1光纤压力传感器应变体力学模型设计

根据膜片式压力传感器的结构和特点,利用材料力学相关知识对其弹性体进行设计,并建立力学模型;根据膜片式压力传感器灵敏度要求,运用有限元分析方法进行分析,建立了既符合实际又简化的有限元模型;研究了弹性体的结构参数、温度、载荷等因素对传感器灵敏度的影响,为光纤光栅膜片式压力传感器的优化设计提供依据。     

基于巨磁阻效应的电流传感器研制

通过叠合两个巨磁阻芯片构成差分式巨磁阻组件.差动结构能够改善电流传感器的零偏电压,抑制温度漂移.同时引入反馈电路构成闭环系统,有效地提高了传感器的输出线性度,因此提高了电流测量精度.分析了传感器的工作原理,给出了系统闭环传递函数,并进行电路仿真和有限元仿真,分析验证方案的合理性.制作了样机,实验结果表明,所研制闭环结构...     

ANSYS在腕力传感器结构设计中的应用

腕力传感器是一类重要的机器人传感器,腕力传感器的弹性体结构设计好坏直接影响到传感器的各项指标.由于腕力传感器结构复杂,各输出通道之间往往存在着干扰,通常采用实验的方法来进行标定,但标定的结果往往不够精确.利用所研制的一种新型机器人多维腕力传感器的结构,提出了一种利用有限元分析软件ANSYS对其维间干扰作定量分析的方法,分析结果证实了该传感器弹性体结构设计的合理性.     

基于霍尔元件的液压阀阀芯位移传感器

针对液压阀阀芯位移检测问题,提出了一种基于线性霍尔元件的液压阀阀芯位移传感器结构.介绍了新型耐高压霍尔传感器的结构组成和工作原理;建立了传感器磁场有限元仿真模型,仿真分析了磁感应强度与阀芯位置之间的关系;最后研制了新型耐高压位移传感器,并进行了实验研究,结果表明:在2mm范围内传感器的线性度为1％,可用于比例阀芯位移检...     

基于有限元模拟的薄膜热流计结构设计及优化

精确的热流测量对航空航天领域发动机设计及使用过程至关重要.薄膜热流计以其体积小、热容量小、干扰小、不破坏部件表面气流等显著优势,成为发动机热端部件表面热流测量的新方法.针对传统工程经验设计薄膜热流计精确度不高且迭代耗时长的缺点,基于有限元仿真模拟方法,建立了一种薄膜热流计有限元分析模型,综合分析了热流密度、热阻层厚度、热电堆厚度等因素对热流计冷热结点温度梯度的影响,提出薄膜热流计优化思路.分析结果表明,优化后的薄膜热流计具有更出色的热学性能与电学性能.     

Design and characterization of an integrated multifunction micro sensor

This paper describes the design and characterization of an integrated sensor fabricated on the silicon on insulator wafer by micro electro mechanical systems technology. The integrated sensor is comprised of a tri-axis accelerometer, an absolute pressure sensor and a spreading-resistance temperature (SRT) sensor. The optimal size of the sensor structure, natural frequency and cross interference of these three sensors were simulated and determined by finite element analysis. The accelerometer with the cross structure has high sensitivity, good linearity and high response frequency proved by the static and dynamic experiments. The zero-drift, thermal zero-drift and thermal sensitivity of the accelerometer and absolute pressure sensor were also tested. The arrangement of SRT sensor with the wave structure was designed in detail. The optimal location of the SRT sensor was at the edge of chip to avoid stress interference. The integrated sensor with low cost, low mutual interference, smaller volume and good performance can be applied in mobile device, small military plane without driver and some other situations for environmental monitoring.     

热催化气体传感器的特性分析及其设计原则

热催化气体传感器的输出受诸多因素的影响,从理论上分析其输出特性有助于传感器的优化设计和性能评估。从一个热催化气体传感器的典型结构和热催化气体敏感机理出发,应用热平衡方程和热敏电阻的电阻温度关系推导了传感器输出与被测气体浓度、催化反应速度、工作温度以及传感器结构尺寸等之间的定量关系。从推导过程中的诸多假设,得出了热催化气体传感器设计时应遵循的一般原则。     

温度触觉传感器的材质识别仿真研究

采用温度触觉传感器对材质进行识别研究,介绍了一种基于热传导原理的材质识别方法,利用ANSYS软件对温度触觉传感器在不同温度差、不同基板材料和不同被测物体材料不同情形下的热传导进行了仿真实验。仿真结果表明:温度触觉传感器可用于识别吸热系数偏低的材料,接触温度可作为材质识别的一个重要判据。     

基于有限元模拟的薄膜热流计冲击振动分析

实现发动机热端部件热流的精准监测对于发动机的冷却设计和可靠性提高具有重要意义,而薄膜热流计具有结构简单、不影响被测件气动外形以及对流场干扰小等特点。针对航空发动机在运行时产生的高振动及高冲击载荷下的薄膜热流计结构可靠性问题,采用有限元方法,建立薄膜热流计的有限元模型,分析了冲击以及随机振动对热流计结构可靠性的影响,并且提出了优化建议。优化后的热流计的最大位移及最大应力都明显减少,结构的可靠性明显提升,冲击振动测试以及划痕测试的结果也验证了薄膜热流计结构的合理性。     

基于LabVIEW的机床热误差检测系统设计

针对机床高速旋转主轴的安装偏心及各种外界干扰对热误差精确测量的影响,本文选用了精度较高的电容式位移传感器及NI数据采集卡,基于LabVIEW平台开发了一套机床温度和位移数据实时检测系统。该检测系统可实现在主轴高速旋转下位移数据的高速率采样,并采用软件数字滤波方法对位移数据处理。最后将该检测系统进行实验测量,实验结果表明该检测系统具有一定的实用性。     

Characteristics of heated sensors emitting by radiation only

The design of an oven-mounted sensor using a single mount is presented. The sensor is placed in vacuum inside a can. The sensor temperature is maintained constant by means of the heat directly furnished inside the can, the sensor holder being used as a heater. The sensitive part of the sensor is stressless and insensitive to temperature variations of the surrounding medium. Thermal losses occur by radiative transfers. A theoretical analysis of the thermal exchanges is given, pointing out that the thermal losses depend on a parameter which varies only according to the geometry of the device and to the radiative properties of the materials used; moreover, the thermal losses are a function of the sensor and can temperatures. The role of each parameter is evaluated and the emissivity factor of the sensor area is shown to be the main factor ruling the thermal losses. The temperature distribution along the length l of the sensor is calculated, as well as the thermal-gain magnitude of the system. The variation of the standard sensor temperature versus the standard x/l coordinate is obtained. The slope at the origin does not depend on the material properties, and the average value of the sensor temperature is reached for x/l near 0.4. The thermal gain of the device reaches 500 or more for current thermal materials. Using a thermal screen interposed between the sensor and the can, the thermal gain is enlarged by several orders of magnitude. Numerical applications are applied to the case of piezoelectric accelerometers. Thermal gains greater than 10⁶ are achieved, and a drastic reduction of energy consumption occurs relative to the case of classical ovens.     

A flow sensor for liquids based on a single temperature sensor operated in pulsed mode

An anemometric flow sensor for liquids based on a single temperature sensor is presented. The sensor is based on a probe composed by a silicon chip glued to a copper cylinder acting as thermal feed-through. A precise temperature sensor and a resistive heater are integrated on the chip surface. The sensor is operated in pulsed mode to eliminate the interference of the fluid temperature, switching either the heater power or the probe temperature. The results of water flow tests in the range (1–30) l/h are presented. The problem of reducing the duration of the measurement cycle has been addressed with theoretical and experimental arguments.     

Reducing thermal transient induced errors in thermopile sensors in ear thermometer applications

In ear thermometers and similar applications, thermopile sensors have to face a challenging thermal environment. The steady-state sensor temperature as well as the change of sensor temperature, heat flow, and thermal gradients have a significant impact on the sensor's reading. As opposed to the well-known steady-state sensor temperature (so-called “ambient temperature”), the effects of thermal transients have not jet been understood well in the past. They occur when the sensor warms up while the thermometer is inserted into the ear. They have to be treated in addition to the traditional (steady state) ambient temperature compensation.Isothermal packaging of the sensor significantly reduces the error due to thermal transients. This can be combined with mathematical prediction of the remaining error. Based on an analytical thermal model, we show that the error can be represented by a series of derivatives of the sensor housing temperature. Numerical calculation and compensation of the error in only first order combined with an isothermal package allows for an error reduction by the factor of 30.     

一种新型MEMS微波功率传感器的理论模型与优化设计

提出了一种新型的MEMS微波功率传感器.与传统的结构相比,新结构具有测量误差小、设计简单、使用方便等显著优点.然后在全面考虑了热传导、热对流、热辐射三种传热机制的基础上,对传感器的主要部分即热电堆建立了热模型,进而导出了灵敏度、时间常数、噪声的理论解析式.最后根据拉格朗日乘数法原理,以给定的时间常数和噪声大小为约束条件,求得灵敏度达最大时热偶长度和串联数目的最佳值.