新型电场传感器应用于输电线电场测量

基于高性能的微电子机械系统(MEMS)工频电场传感器系统开展了高压架空输电线下电场测量应用研究.为了获得电场分布规律,基于模拟电荷法,建立了输电导线的二维电场计算通用模型.传感器系统核心敏感芯片基于电荷感应原理,采用MEMS技术加工制作.在0~1000kV/m工频电场范围内,传感器系统的总不确定度为1.53%,分辨力达到了20V/m.仿真与测试结果表明:35kV与10kV输电线下的电场计算结果与传感器系统的测量结果偏差分别为6%和10%,并与传统的Narda EFA-300电磁场分析仪测量结果具有较好的一致性.     

Characterization of microdevices for ferrous chloride separation for biosensing applications

Ferrous chloride has a variety of applications such as a reducing flocculation agent in waste-water treatment, especially for wastes containing chromate, in the laboratory synthesis of iron complexes and it is employed as a reducing agent in many organic syntheses. The device used for experiment was fabricated on the silicon wafer as support for two electrodes in a SU8 polymer microchannel with an inlet, for the injection of aqueous solution of ferrous chloride, and two outlets, for the two by-products of separated solutions. The various parameters of the device were measured by White Light Interferometer (WLI) and Scanning Electron Microscopy (SEM). The magnetic field created by applying different types of potential between two electrodes determined ferrous chloride to separate in ferrous oxide and chlorine (in gaseous form). If a protein is added in this solution we have the possibility to immobilize the protein on the iron particles and on the channel area. The electrical results were collected using a semiconductor system analyzer Keithley and were examined subsequently. The Fe complexes deposited on the electrodes were characterized by XRD analyses.     

Electrokinetically driven concentration of particles and cells by dielectrophoresis with DC-offset AC electric field

Insulator-based dielectrophoresis (iDEP) has been successfully used for on-chip manipulations of biological samples. Despite its effectiveness, iDEP typically requires high DC voltages to achieve sufficient electric field; this is mainly due to the coupled phenomena among linear electrokinetics: electroosmosis (EO) and electrophoresis (EP) and nonlinear electrokinetics: dielectrophoresis (DEP). This paper presents a microfluidic technique using DC-offset AC electric field for electrokinetic concentration of particles and cells by repulsive iDEP. This technique introduces AC electric field for producing iDEP which is decoupled from electroosmosis (EO) and electrophoresis (EP). The repulsive iDEP is generated in a PDMS tapered contraction channel that induces non-uniform electric field. The benefits of introducing AC electric field component are threefold: (i) it contributes to DEP force acting on particles, (ii) it suppresses EO flow and (iii) it does not cause any EP motion. As a result, the required DC field component that is mainly used to transport particles on the basis of EO and EP can be significantly reduced. Experimental results supported by numerical simulations showed that the total DC-offset AC electric field strength required to concentrate 15-μm particles is significantly reduced up to 85.9% as compared to using sole DC electric field. Parametric experimental studies showed that the higher buffer concentration, larger particle size and higher ratio of AC-to-DC electric field are favorable for particle concentration. In addition, the proposed technique was demonstrated for concentration of yeast cells.     

测量电场的铌酸锂光传感器综述

铌酸锂(LiNbO3)光传感器具有灵敏度高,不受外部电磁场干扰的特性,吸引了越来越多科研工作者的注意。对基于不同类型传感器的制作工艺、传感原理和适用范围,介绍了3种用于测量电场的铌酸锂光传感器,它们分别是:基于Mach-Zehnder波导调制器与微多环天线的集成方位角铌酸锂光传感器;铌酸锂介质波导光传感器;室温直接粘接的铌酸锂晶体层高电压光传感器。     

Modelling a droplet moving in an electric field

Droplets on insulators in outdoor high-voltage equipment move and leave water films on the insulating material. These films further the development of undesirable electric currents or even flash-overs. The paper deals with the behaviour of a single droplet laying on a solid support in a strong electric field. Inside the solid support two electrodes generate the electric field. Although the experiment is designed so that the electric field is nearly homogeneous in the absence of a droplet, the remaining inhomogeneity motivates the discussion of its influence on the droplet. Therefore, water droplets at general positions on the experimental set-up are considered. The deformation of the droplet is calculated together with the total force acting on whole the droplet. The total horizontal force initiates the droplet to move. An analytical proof of the existence of a non-vanishing total force acting on an extended uncharged body in a general electric field is given.     

激光供电脉冲电场传感器设计

为解决复杂电磁环境中脉冲电场传感器的供电问题,设计制作了一种基于激光光电池供电的脉冲电场传感器,该传感器由激光光电池供电电路、电光转换电路和单极子天线构成。设计制作了采用恒流源电路驱动半导体激光器、光电池、来驱动构成的激光光电池供电电路,可将输入的特定波长的激光能量转换成电能提供给负载或者传感器端使用,从而能够实现远距离的非接触式供能。设计了一套系统标定设备,在一定空间内产生符合测试要求的电场。不同类型的传感器被安装在测试空间内,用来测量模拟器所产生的电场和磁场以及测试体内部电场、磁场等数据及波形,对电场传感器瞬态及稳定标定。测试结果显示,研制的脉冲电场传感器测量3dB带宽在20kHz~500MHz,动态范围100V/m~60kV/mm,负载阻抗125Ω,线性度优于10%,瞬态标定满足上升沿小于3.5ns。     

Fabrication of three-dimensional magnetic microdevices with embedded microcoils for magnetic potential concentration

Novel magnetic microdevices were developed for magnetic field generation and concentration and successfully characterized and tested for magnetic potential focusing which is very important for various MEMS applications such as magnetic particles manipulation. These microdevices have been fabricated using an innovative processing sequence which eliminates many problems associated with other fabrication techniques and provides a platform for adding other subsequent fabrication steps required to integrate the microcoils with other microcomponents. They consist of high aspect ratio planar coils made of electroplated copper embedded in the silicon substrate, with ferromagnetic pillars and backside plates made of a CoNiP ternary alloy. A large magnetic field gradient is generated and enhanced by two structural parameters: the small width and high aspect ratio of each single conductor and the ferromagnetic pillars positioned at high flux density locations. This arrangement creates very steep magnetic potential wells, in particular at the vicinity of the pillars. The manipulation of micromagnetic particles in a static and continuous flow conditions has been demonstrated.     

Random field model for integration of local information and global information

This paper presents a proposal of a general framework that explicitly models local information and global information in a conditional random field. The proposed method extracts global image features as well as local ones and uses them to predict the scene of the input image. Scene-based top-down information is generated based on the predicted scene. It represents a global spatial configuration of labels and category compatibility over an image. Incorporation of the global information helps to resolve local ambiguities and achieves locally and globally consistent image recognition. In spite of the model's simplicity, the proposed method demonstrates good performance in image labeling of two datasets.     

3D model of a droplet in an electric field

Outdoor high-voltage equipment is exposed to rain and moisture. Water droplets on the surface of insulators influence negatively the insulating and hydrophobic material properties. The shape of the droplets signifies the state of the aging material. The present paper develops a numerical procedure to determine the three-dimensional shape of water droplets in strong electric fields. That includes the solution of a feed-back problem between the droplet shape and the electric field. Here we concentrate on the particular features in three dimensions and compare the resulting droplet shapes with a 2D droplet model.     

Lift-off of a conducting sessile drop in an electric field

A conducting drop in partial wetting regime, placed on the lower electrode of a parallel-plate capacitor and surrounded by a dielectric fluid, is considered. The drop, initially flattened by gravity, is elongated by the electrostatic force and possibly lifts-off when a uniform DC electric field is applied. The electrostatic force and the lift-off condition were calculated in two previous articles, respectively, for undeformable and for slightly deformable drops in the absence of gravity (zero Eötvos number). In this paper, numerical models are put to work to study accurately the complex lift-off process resulting from the competition between gravitational, electrical and capillary forces. Large deformations of the drop surface at any value of the Eötvos number may be addressed by such a numerical procedure. Computational results allow assessing the accuracy and limits of previous analytical and asymptotic relations.     

Measurement of handle forces for crimping connectors and cutting cable in the electric power industry

Overhead and underground line work in the electric power industry is physically very strenuous and can expose workers to musculoskeletal disorders (MSDs), particularly in the upper extremity. Crimping compression connectors—such as sleeve connectors and lugs—and cutting cables are two of the most frequent tasks that line workers perform. Line workers at many utilities in the US crimp connectors and cut cable with long-handled manual tools. However, the actual magnitude of the forces applied to the handles of these tools is not known. The objectives of this laboratory study were to measure the forces applied to the handles of a manual press and a manual cutter in order to connect typical wire gauges and cut common cables, respectively. The handles of the manual press and cutter were attached to the drive cylinder and load cell of an Instrom Material Testing System, and peak forces exerted against the handles were measured. Results showed that the outer die of the manual press required about 50% more handle force than crimping connectors with the inner die location. The peak handle forces required to cut aluminum conductor cable as large as 2 cm diameter exceeded 500 N and were about 200 N greater than the peak forces to compress connectors manually. When the peak force data were compared to strength capabilities reported in the literature, less than 1% of the general population was found to have the maximum strength to manually make one crimp on a common overhead connector. Less than 1% and approximately 50% of the female and male general population, respectively, were found to have the maximum strength to manually cut a cable with a 2 cm diameter conductor. Handle force data from this study provide a biomechanical framework for explaining how the job demands of overhead and underground line workers could possibly cause MSDs.

Relevance to industry

Electric power utilities can review their work practices and tools in order to determine whether they can reduce the exposure of their workers to risk factors of MSDs, as well as reduce their cost of health care. Manufacturers of crimping and cutting tools can use the experimental approach in this study to measure the external forces required for their respective tools and then set quantitative force benchmarks to improve the design of their tools.     

基于虚拟仪器的变频调速电机电参数的测试

介绍了基于虚拟仪器对变频调速电机参数测试系统，给出了硬件设计方法、软件模块构成。提出了几种提高测试准确度的方法及其实现措施。它与传统测试方法比较，具有硬件简单、软件应用灵活、测试准确度高等特点。     

A high-order implicit procedure for the 3-D electric field in complex magnetogasdynamic simulations

An approximately factored compact-difference-based method, up to sixth-order accurate in space, is developed to obtain the electric field in magnetogasdynamic (MGD) interactions. The three-dimensional current continuity equation is solved on curvilinear meshes for the general case where electrical conductivity is a spatially varying tensor due to the presence of Hall and ion-slip effects. Compatible high-order boundary conditions are described for electrodes and insulators. Several computations verify the formulation, including a test case with an analytic solution and several cases for the potential arising between continuous and segmented electrodes with variable conductivity and velocity profiles. Issues related to the computation of the electric field in the high-speed regime are addressed by computing the initial induced field in a Type IV shock-on-shock interaction under a frozen velocity field assumption.     

改进人工势场法在机器人路径规划中的应用

为解决传统人工势场法用于机器人路径规划时会出现规划失败的问题,分析了由于局部极小点问题而导致规划失败的原因。在已改进人工势场函数的基础上,提出了通过增加虚拟目标点和原目标点共同对机器人产生引力的方法来解决传统人工势场法中出现的局部极小点问题。在Mobotsim中对算法的仿真结果表明了该方法的可行性和有效性。     

箭载电场数据处理软件设计

本文介绍了对箭载电场仪数据的处理及分析软件。该软件是将电场仪及其搭载设备所提供的原始数据转换成可用的子午工程数据产品,主要实现原始科学数据的格式转换和附加电场的处理。文章阐述了数据处理方法及软件的具体功能,以及软件设计的核心算法,该系统功能完善。     

An alternate point‐wise scheme for electric field integral equations

A point‐wise approach that can be used efficiently in the numerical solution of Electric Field Integral Equations is introduced. The algorithm is based on the so‐called magic distance concept, which defines exactly the point‐to‐point equivalent of a four‐dimensional integral. Magic distance values are rigorously obtained in the electrostatic case and their usefulness is demonstrated. The concept is generalized to the electrodynamic case, resulting in a family of very simple “magic‐distance inspired” algorithms that maintain the overall accuracy of Galerkin formulations without appreciable deterioration in the overall accuracy. © 2013 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2013.     

Fiber-optic polarization interferometer with an additional phase modulation for electric field measurements

A fiber-optic polarization interferometer with two electrooptic elements (sensor and additional modulator) designed for measuring electric field intensity is suggested and analyzed. The paper focuses on the theoretical and experimental demonstration of the principles of operation of fiber-optic circuits that generate and process the optical signals and provide measurement. The advantage offered by our interferometer is that it allows, in contrast to conventional configurations, additional modulation of the phase difference between interfering waves by a modulator in the instrumental part of the device and the use of available methods of phase detection developed for fiber-optic interferometric sensors. A laboratory prototype has been successfully tested.     

Stepwise gray-scale light-induced electric field gradient for passive and continuous separation of microparticles

This article presents a gray-scale light-induced dielectrophoresis (GS-LIDEP) method that induces the lateral displacements normal to the through-flow for continuous and passive separation of microparticles. In general, DEP force only can affect the particles within very local areas due to the electric field is exponentially decayed by the distance away from the electrodes. Unlike with conventional LIDEP, a broad-ranged electrical field gradient can easily be created by GS pattern illumination, which induces DEP forces with two directions for continuous separation of particles to their specific sub-channels. Candia albicans were effectively guided to the specific outlet with the efficiency of 90% to increase the concentration of the sample below the flow rate of 0.6?μl/min. 2 and 10?μm polystyrene particles can also be passively and well separated using the multi-step GS pattern through positive and negative DEP forces, respectively, under an applied voltage of 36?V_p–p at the frequency of 10?kHz. GS-LIDEP generated a wide-ranged DEP force that is capable of working on the entire area of the microchannel, and thus the mix of particles can be passively and continuously separated toward the opposite directions by the both positive and negative GS-LIDEP forces. This simple, low cost, and flexible separation/manipulation platform could be very promising for many applications, such as in-field detections/pretreatments.