图解铁磁交流稳压器

交流稳压器通常是利用铁磁非线性特性构成,属于铁磁稳压器,它是由铁磁饱和元件再加谐振电容构成的稳压器。1、铁磁饱和现象一个线圈通过电流时,线圈中便有磁场产生,描述这个磁场有两个物理量,一个是磁场强度,用H来表示,它与线圈的圈数和流过线圈的电流强度的乘积(又称安匝数)有关;另一个是磁感应强度(又称磁通密度),用B来表示,B的大少除与安匝数有关外,还与线圈中的介质有关。如果介质是空气,那么H和B数值相等,如果介质是铁磁材料时,同一线圈流过同样的电流     

基于内部阵列电极的电容层析成像系统

为了研究电容层析成像系统在测量高介电常数流体中的应用,设计了一套具有内部阵列电极的电容层析成像传感器,改善了传统传感器的灵敏度和非线性特性,拓宽了系统的测量范围。用蒸馏水作为连续相介质进行了数据采集和图像重建,并进一步研究了介质电导率对系统成像的影响。实验表明,该系统可以实现高介电常数介质的测量,并且可用来测量具有微弱导电能力的物体。     

低温介质下电容液位测量系统的研究

针对低温介质的贮存和使用问题,设计一种数字化的高精度电容液位测量系统样机;采用连续与分节相结合的方式对电容液位计的结构进行优化,系统的硬件部分以微控制器为核心,将电容的变化量转换为数字信号,实现与上位机的网口通信;通过电容标定工具和液氢对样机的性能进行验证,结果显示,系统的电容测量精度优于0.1 pF,且能够有效分辨出1.37 mm的液氢液位变化,满足低温介质液位测量的精度要求。     

多节电容式煤位传感器

探讨了变介质型电容传感器在煤仓煤位测量中的应用，及脉宽调制式测量电路的设计。     

电容层析成像技术分辨油水两相能力的仿真研究

电容层析成像技术主要用于测量介电常数相近的两相或多相介质,该文采用有限元仿真分析手段,以介电常数相差较大的油水两相介质为实验对象进行仿真,研究结果表明电容层析成像系统仍具有一定的分辨能力。     

介电常数未知条件下ECT图像重建的SVC算法

在电容层析成像(ECT)系统的实际应用中,两相流和多相流是最普遍的流体情况.不仅是由于被测介质的介电常数会随着温度等环境的变化而变化,而且还由于被测场域中存在其他介质,会使得测量时出现介质未知的情况.利用支持向量机(SVM)算法具有良好泛化性的特点,提出采用基于SVC(support vector classification)的电容层析成像图像重建算法对未知介电常数对象进行图像重建.仿真结果表明,该算法能有效适应介质多样性变化,即对于不同介质,该算法都能有较高的图像重建精度.     

电容传感器成像敏感场若干影响因素探讨

电容层析成像(ECT)是一项基于图像的过程检测技术,具有实时性好,非侵入性,价格低廉的优点,适用于多相流检测,并已开始被引入两相流的测量中.在对电容传感器进行数学描述的基础上,建立了电容敏感场分布的数学模型及其有限元模型,介绍了敏感场的计算方法,利用有限元法研究了敏感场电势的分布规律.仿真实验表明:灵敏度分布函数受到介质分布的影响.     

多孔介质中天然气水合物二维模拟实验装置

本文介绍了一种天然气水合物模拟实验装置,该装置能模拟多孔介质中天然气水合物的生成和分解过程.能够通过测量平板内探针的电容判断水合物的状态变化.实践证明,该装置工作稳定可靠,性能符合实验要求.     

任楼煤矿电容电流危害分析与治理研究

针对中性点不接地系统单向接地电容电流易造成配电网络次生灾害和设备损害、易产生单向电弧接地过电压和铁磁谐振过电压的问题,分析评估了任楼煤矿电网电容电流的测试数据,根据评估结果制定了电容电流治理方案,即将中性点不接地系统改为中性点经消弧线圈接地运行方式,并给出了具体实施方案。运行结果表明,该方案大大减少了高幅值电弧接地过电压发生的几率,抑制了铁磁谐振过电压,有利于提高电缆寿命。     

发明与专利

差动电容靶式流量传感器 【摘要】本实用新型涉及一种差动电容靶式流量传感器,其包括有差动电容探头和靶片,差动电容探头由振动管、陶瓷基体、两个半圆筒极板、引线、引线屏蔽管组成,靶片安装在差动电容探头的振动管尾部。靶片可以通过螺纹连接或焊接固定连接在振动管尾部。该传感器也可设计成管道型靶式流量计或球阀插入型靶式流量计,适应于不同大小口径的管道中各种介质流量的测量。本实用新型结构简单,易加工和批量生产,安装和施工简便,其可靠性高,性能好,测量精度高,适用流量测量广泛,温度范围宽,抗振动干扰,测量流量范围宽,特别适用于大型管道中低流速及脏污介质的流量测量。     

数字式、微型化、低功耗电容测微仪的研究

介绍一种新型电容测微仪.通过测头与测量电路的一体化设计,精缩了仪器体积;采用差动测头结构,减少了由于环境变化引起的测量误差;使用数字信号传输测量结果,增加了信号的传输距离,提高了抗干扰能力.给出了电容量和被测距离之间的非线性关系的直线拟合方法.研究结果表明:有效直径为3 mm的传感器测量范围为±80 μm,分辨力达到0.01 μm,时间稳定性达到0.01 μm/h.     

基于电容式传感测头的电容检测系统的设计

针对纳米尺寸测量领域的不同测量要求,尝试开发一种基于电容传感器的微触觉测头及其电容检测系统。阐述了测头的结构原理和电容传感器的工作原理,研制了基于电容传感器的微触觉测头。测头的测量原理表明:微小电容检测电路是整个电容检测系统的关键部分。该微小电容检测电路选用电容/数字转换器(CDC)AD7747芯片,分别编写了单片机与该芯片的I2C通信程序和单片机与上位机间的串行通信程序,实现了微小电容的采集和处理,简单进行了电容式传感测头的轴向性能的测试实验。实验表明:电容式微触觉测头的分辨率为0.02μm,重复性较好,证实了此电容式微触觉测头的可行性。     

Extension to the analytical model of the interdigital electrodes capacitance for a multi-layered structure

Interdigital electrodes (IE) are one of the most used transducers in different technical and analytical applications with the particular importance in the field of chemical and biological sensors. With the recent demand for lab-on-a-chip devices and the need for sensors miniaturization it becomes common the use of such transducers in structures with several dielectric layers (either substrates or superstrates). In a previous a work we proposed a model for the computation of the capacitance of these multi-layered structures using the techniques of conformal mapping and partial capacitance. Until now, that model has been used in applications where the permittivity of consecutive layers monotonically decreases from layer to layer (as we move away from the electrodes plane) giving excellent results. New applications, such as the use of Si/SiO₂ substrates (to promote very smooth surfaces for electrodes deposition) or the use of passivation layers for the protection of electrodes (e.g. from liquids), among others, represent a new challenge for the computation of the overall capacitance since in these devices the permittivity can decrease from layer to layer. Under these conditions the original partial capacitance technique needs to be modified to include these new configurations. In this work we will discuss a new approach, splitting the concept of partial capacitance in parallel partial capacitance and serial partial capacitance where new conformal mapping transformations are proposed for the latter case. Hence this novel approach will extend our previous analytical model in order to account for the cases where there is a decrease in the permittivity from layer to layer. The results are compared with finite element simulation and experimental results.     

参数调制探针式电容土壤水分传感技术研究

电容传感器是实现土壤水分低成本检测的主要途径,土壤水分中电导对土壤水分影响很大,为了消除电导影响,研究了一种新颖的基于参数调制的探针电容土壤水分传感器,分析了参数调制技术消除电导机理,并建立了相应数学模型,设计了参数调制式探针电容土壤水分传感器的检测电路和数据处理系统,通过参数优化得到了一种能够实现在线测试土壤水分的探针电容传感器及检测仪器.试验表明,随着土壤含水量的变化,其探针电容传感器响应有较大的变化,且在低于25%的含水量范围,土壤含水量与被测电压之间呈线性关系.     

Computer-aided measurement plan for an impeller on a coordinate measurement machine with a rotating and tilting probe

This paper presents a computer-aided measurement plan (CAMP) for an impeller on a coordinate measurement machine (CMM) with a rotating/tilting probe. The blade surfaces of a machined impeller were measured exactly to secure the machining tolerance and surface finish of the impeller. CMM with a rotating and tilting probe is commonly used for this measurement. However, it is not easy to evaluate all the points on the impeller surfaces due to the time-consuming nature of the CMM measurement. In addition, many points cannot be easily accessed by the CMM probe due to the interference between the probe and the impeller blades. Furthermore, the inherent complexity of the existing teaching operation of a probe using a joystick suggests the necessity of developing a new method for the measurement planning of an impeller. Thus, this paper proposes a CAMP for effectively gauging the inspection points based on the ruled line information of the impeller blade surfaces. The proposed plan partitions the surfaces into several measurement regions based on the ruled lines of a blade surface and the approach vectors of the probe. Finally, a case example for an impeller is presented to demonstrate the effectiveness of the proposed strategy.     

小孔内径测量的传感器精度分析

针对小孔的结构特点,介绍了电容传感器探针测量小孔孔径的原理;分析了测量时电容传感器由于参数的线性化、电容探针与小孔的中心线偏心带来的测量误差;并针对以上因素影响,采取了自动对中机构实现测量过程中的最小化偏心,通过标定得到了孔径值与测量值之间的对应关系。实验结果表明,系统的重复性精度可达到0.186μm,稳定性能达到6 h内漂移不超过0.375μm,该指标完全可以满足实际测量要求。     

电容式力感知牙周探针设计建模与实验研究

针对当前牙周探针在探诊力控制方面的不足,提出一种基于悬臂梁挠曲效应的差动电容式力感知牙周探针解决方案,设计了探针验证结构,建立了探诊力作用下具有不规则形状的探针工作尖的挠曲模型,导出了探诊力和差动电容之间的求解方程,并通过仿真和实验对模型与方程进行了验证。结果表明,所建立的探针工作尖挠曲模型与静应力仿真结果的最大相对误差不超过±4.5%,所设计的力感知牙周探针多次重复探诊力检测实验的标准差小于均值的0.1%,所导出的求解方程的计算值与实验数据之间趋向一致,以探诊力为拟合权重进行修正后全量程的平均偏差为2.49%,具备进一步产品开发的可行性。     

一种新型波高测量系统的设计

波高测量是海洋工程模型试验中的一项重要内容,为了能够准确、稳定地实时测量实验水池中的波浪,采用了一种新型的波高测量系统设计方法:首先利用液位高度与波高传感器电容量的线性关系将波高测量问题转化为电容量测量问题;其次利用波高传感器的电容量与其充放电时间的关系将波高传感器的电容量测量问题转化为充放电时间的检测问题;然后运用单片机片内模拟比较器和定时器的输入捕获功能将电容充放电时间转化为计数值;接下来将计数值通过USB接口送到上位机进行数据处理及波形显示;最后进行实验测试,实验结果表明所采用的波高测量方法是有效的,且具有线性度好、灵敏度高、精度高的优点。     

Design,analysis and simulation of a novel linear capacitive tilt micro-sensor

A new capacitive structure for tilt sensor based on the MEMS technology is designed, analyzed and simulated. With a detailed analysis, we achieve to a precise relation between capacitance and inclination angle. Taking advantage of cylindrical structure in our design, we reach to a linear relationship between capacitance and tilt angle. In three designs of our capacitive tilt micro-sensor, there are 1, 2 and 4 micro capacitors. These capacitors have a common plate of mercury which is movable. Another plate is fixed. Displacement of mercury according to the deflection tends to the variations of capacitors and subsequently total capacitance of the tilt micro-sensor changes. In each of three designs for this micro-sensor, output capacitance (C_out) is introduced with a special equation for obtaining a linear and continues relationship between C_out and tilt angle. The last proposed micro-sensor structure with 4 micro capacitors, shows linear relationship for C_out over tilt measurement range of ?180° to +180° on one axis besides proper sensitivity.     

A Parallel Implementation of a Fast Multipole-Based 3-D Capacitance Extraction Program on Distributed Memory Multicomputers

Very fast and accurate 3-D capacitance extraction is essential for interconnect optimization in VLSI ultra-deep sub-micron designs (UDSM). Parallel processing provides an approach to reducing the simulation turn-around time. This paper examines the parallelization of the well-known fast multipole-based 3-D capacitance extraction program FASTCAP, which employs new adaptive and preconditioning techniques. To account for the complicated data dependencies in the unstructured problems, we propose a novel generalized cost function model, which can be used to accurately measure the workload associated with each cube in the hierarchy. We then present two adaptive partitioning schemes, combined with efficient communication mechanisms with bounded buffer size, to reduce the parallel processing overhead. The overall load balance is achieved through balancing the load at each level of the multipole computation. We report detailed performance results on a variety of distributed memory parallel platforms, using standard benchmarks on 3-D capacitance extraction.