Optical current transducer with bulk type Bi12SiO20 faraday sensor for power systems

Two types of optical current transducers (OCTs) have a bulk Faraday sensor inserted into the gap of an iron core and a porcelain insulator with optical fiber. The sensor consists of Bi₁₂SiO₂₀ (BSO) single crystal, a polarizer, and an analyzer. The OCTs satisfied the target performance requirement for fault location and metering and demonstrated maintained performance at some power utilities in Japan and the US. We have developed a fault location system that immediately detects the fault current with the OCTs, there by locating the fault section. The OCT can easily replace the existing support insulators for the disconnecting switch without any modifications to structure height or bus-bar. For metering requiring 0.3% class accuracy, use of a BSO with right optical rotatory power combined with BSO with left optical rotatory power results in a Faraday sensor with improved temperature characteristics. The OCT demonstrated 0.3% class accuracy for metering described in the current transformer Specifications of IEEE C57–13, 1993.     

五象限法声源自动跟踪器

介绍由两同心圆组成的等投影面积五象限声－电测量装置的工作原理。当声波与声－电转换器的主要测象限垂直时，其声波在主要测象限内产生的声－电电压最强。根据声－电电压的变化大小来确定声源的方向，实现自动跟踪。     

800Hz Terfenol-D鱼唇式弯张换能器

本文研制了800Hz Terfenol-D鱼唇式弯张换能器，换能器设计中采用永磁偏磁场和能有效抑制涡流损耗的闭合磁路结构，最高声源级185dB，-3dB带宽180Hz,这种鱼唇工弯张换能器克服了连续直流提供偏磁场时发热强的缺点，并且仅需要普通的功率放大器，更适于长时间连续工作，使这一新型低频大功率水声换能器趋于实用化。     

A systems feedback representation of piezoelectric transducer operational impedance

An analysis of thickness-mode piezoelectric transducer impedance under a variety of mechanical load conditions is presented. A wideband, systems model is used to describe this impedance, which is representative of the electrical input impedance in the transmitting mode and the electrical output impedance for the receiving mode.For a fixed input voltage, the total current flowing through the transducer is considered as the vector sum of two current quantities. Firstly, an input current arising directly from the applied voltage source and secondly, a feedback current, which is generated by secondary piezoelectric action. By treating the problem in this manner, an extremely valuable insight into the nature of the electrical characteristics is provided. Complex variations in the impedance behaviour are readily explained and the physical processes that contribute to such deviations are clearly isolated.     

Dynamic calibration of shock overpressure transducers

Piezoelectric transducers for dynamic overpressure measurements are commonly calibrated with static or quasistatic loads and the calibration is extrapolated to frequencies up to 30% of the resonant frequency of the piezoelectric crystal. Sinusoidal pressure generators are also used for dynamic calibration up to 500 Hz in the range of 3 MPa. This paper describes a method for dynamic calibration using transient overpressures, with rise time of 2 μsec and width 40 μsec, generated by exploding wires in air. The calibration is done in the range of 600 kPa.     

A simple,corrosion-resistant flow cell for laser-induced photoacoustic spectroscopic detection of high-performance liquid chromatography effluents

Summary A simple, corrosion-resistant and non-destructive flow cell optimized for laser induced photoacoustic spectroscopic detection of HPLC effluents is described. The characteristics and analytical figures of merit of the flow cell are presented. Application of the flow cell to the detection of polynuclear aromatic hydrocarbons in HPLC effluent is demonstrated. Limits of detection were on the order of tenths of parts per million. Comparisons with the conventional UV absorbance detector and among various laser powers are discussed.     

A multiple function sonar rangefinder for divers

The rangefinder described here is a self-contained instrument for hand-held operation by a diver for searching, tracking, navigation and surveying applications. It has four modes: 1 — to measure range to a passive target directly to ± 1 m; 2 — to measure range to a passive target indirectly to ± 0.1 m; 3 — to measure range to a coded transponder to either ± 1 m or ± 0.1 m; 4 — to indicate the presence of multiple targets downrange where each target occurs in a selected range interval. The pulse echo principle is employed, with pulses typically 250 μs long. The carrier frequency of 300 kHz can be altered easily if required by changing the transducer array.     

A theoretical analysis of a piezoelectric ultrasound device with an active matching layer

This paper investigates the use of magnetically active materials in the matching layer of a piezoelectric transducer. This then allows the performance of the device to be dynamically altered by applying an external field. The effect that this new matching layer has on the performance of a typical device is theoretically investigated here. It transpires that the additional flexibility of an active matching layer can be used to maintain the efficiency of the device as the external load is varied.     

Study on the radial composite piezoelectric ceramic transducer in radial vibration

A new type of radial composite piezoelectric transducer in radial vibration is developed and analyzed. The radial composite transducer consists of a piezoelectric ceramic thin ring polarized in the thickness direction and a metal thin circular ring. They are connected together and excited to vibrate in the radial direction. The radial vibrations of a piezoelectric ceramic thin ring and a metal thin circular ring are analyzed, respectively. Their radial electro-mechanical equivalent circuits are obtained. Based on the electro-mechanical equivalent circuits and using the boundary conditions between the piezoelectric ceramic thin ring and the metal thin circular ring in the radial direction, the electro-mechanical equivalent circuit of the radial composite piezoelectric transducer is derived out and the resonance frequency equation is obtained. The relationship between the resonance frequency and the geometrical dimensions of the transducer is analyzed. Some radial composite piezoelectric transducers are designed and manufactured. The resonance frequencies and the anti-resonance frequencies, the electro-mechanical equivalent circuit parameters are measured. The effective electro-mechanical coupling coefficient and the mechanical quality factor are calculated. It is illustrated that the measured radial resonance frequencies are in good agreement with the theoretical results from the resonance frequency equation.     

导电聚合物构建的高性能固态离子选择电极

基于最新研究文献和自身研究工作,系统总结了以导电聚合物构建的各种高性能固态离子选择电极.导电聚合物所特有的共轭结构以及电子导电和离子导电的双重导电功能使其可以作为离子-电子转换器,从而实现对离子的传感响应与探测.由聚苯胺、聚吡咯和聚噻吩等导电聚合物为转换中间层而构建的离子选择电极可以实现纳摩尔浓度水平的离子传感探测,有望在环境监测、药物医疗和食品安全等诸多方面发挥重要作用.