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.     

Frequency fine-tuning in Class IV flextensional transducers

Class IV flextensional transducers (FTs) are the best-known FTs in literature. These are light-weight projectors (compared to the conventional Tonpilz designs) with capability for high power delivery at low frequencies. The resonance frequencies of this type of transducers are known to be dominantly dependent on the characteristics of the outer shell than on the driver stack. Consequently, the method of achieving fine-tuning of the transducer by modifying the characteristics of the stack, as practiced in the case of Tonpilz designs, is not very effective. This paper describes a method for fine-tuning of the frequency of a Class IV FT, which involves only a modification of a pair of small components used for coupling the stack to the transducer. The effectiveness of the method is examined by finite element modelling using the package ATILA, in the case of a 3 kHz aluminium shell transducer. Experimental results are also presented.     

HIGH-FREQUENCY VIBRATIONS OF CORRUGATED CYLINDRICAL PIEZOELECTRIC SHELLS

Coupled extensional and flexural cylindrical vibrations of a corrugated cylindrical piezoelectric shell consisting of multiple pieces of circular cylindrical surfaces smoothly connected along their generatrix are studied. To validate the results for the case of relatively thick shells or equivalently high-frequency modes with short wavelengths, existing analysis is extended by considering shear deformation and rotatory inertia. An analytical solution is obtained. Based on the solution, resonant frequencies and mode shapes are calculated.     

多层铁电陶瓷击穿分析及优化

建立了多层串联PZT95/5爆电换能组件3维数值模型,对固化封装条件下陶瓷介质击穿问题进行了计算分析,计算结果表明：在不改动器件外部结构尺寸条件下,采用等厚度PZT95/5叠片结构布局对进一步提高输出电压方面存在瓶颈。为克服上述影响以及降低爆电换能组件击穿概率,提出了PZT95/5铁电陶瓷非等厚度布局解决方案。为实现上述设想,通过引入不等式约束条件计算得到一组非等厚度优化布局,将爆电换能组件所用PZT95/5铁电陶瓷数量减至19片,同时有效实现该布局下,各片PZT95/5陶瓷电压均低于对应厚度击穿电压的优化目标。     

用来激励高频超声换能器的电激励源

讨论了超声换能器的几种激励方法，分析了三种常用激励方法在激励高频超声换能器时的特点及其同局限性，我们雪崩ＭＡＲＸ电路制作的单极窄脉冲能地激励率高达１００ＭＨｚ的换能器并取得了较好的结果。     

基于球壳内壁反射的球形换能器自易校准方法

基于球形换能器发射的脉冲球面声波及其在同心球壳内壁的反射,应用机电互易定理,导出了在球面波发射回波声场中,用于校准球形换能器的互易常数。以此为基础,提出一种使用封闭球壳反射器的自易校准方法,通过一次测量即可得到球形换能器的5个基本电声参数。进一步,将自易法校准所得的电压灵敏度换算成平面波声场中定义的标准灵敏度,给出了换算系数。为确定该换算系数,发展了对换能器散射系数进行测量的方法。在25~63 kHz频率范围内,对半径10 mm的球形换能器实施了自易校准。结果表明,测得的电压灵敏度的标准不确定度估计优于0.9 dB。     

Properties of cat-eye modulating retro-reflector and its application with piezoelectric transducer

Piezoelectric cat-eye modulating retro-reflector (MRR) is the core component of an acousto-optic retro-identification system. The influence of the optical parameters (link distance l, lens focal length f and the detector diameter r) to the cat-eye effect was analyzed theoretically and experimentally. A piezoelectric cat-eye retro-identification (PCERI) system was built, and an information transmission ratio of 2 kHz was achieved which can satisfy an access control system.     

基于超磁致伸缩材料的光纤光栅调谐范围研究

研究了基于超磁致伸缩材料实现对光纤布拉格光栅的动态调谐这一方案理论上可获得的最大调谐范围．利用超磁致伸缩换能器的输出特性,进行了超磁致伸缩换能器用于光纤布拉格光栅调谐的实验研究．分析了实验中影响可获得调谐范围的各种因素,如实际可获得的超磁致伸缩材料的特性、光纤布拉格光栅的特性以及换能器结构的设计．进一步讨论了在理论界限的前提下改进该方案可获得调谐范围的措施,并以施加预应力为例进行了实验验证．结果表明,通过给予超磁致伸缩材料合适的预应力,可以较明显地改善最大调谐范围．     

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.     

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。