The Classical Hall Effect in Multiply-Connected Plane Regions Part I: Topologies with Stream Function

Typical Hall plates for practical magnetic field sensing purposes are plane, simply-connected regions with peripheral contacts. Their output voltage is the sum of even and odd functions of the applied magnetic field. They are commonly called offset and Hall voltage. Contemporary smart Hall sensor circuits extract the Hall voltage via spinning current Hall probe schemes, thereby cancelling out the offset very efficiently. The magnetic field response of such Hall plates can be computed via the electric potential or via the stream function. Conversely, Hall plates with holes show new phenomena: 1) the stream function exists only for a limited class of multiply-connected domains, and 2) a sub-class of 1) behaves like a Hall/Anti-Hall bar configuration, i.e., no Hall voltage appears between any two points on the hole boundary if current contacts are on their outer boundary. The paper studies the requirements under which these effects occur. Canonical cases of simply and doubly connected domains are computed analytically. The focus is on 2D multiply-connected Hall plates where all boundaries are insulating and where all current contacts are point sized.

磁场反接制动在煤矿蓄电池机车上的应用

煤矿蓄电池机车经过改造实现平稳的磁场反接制动是可行而有效的。分析了磁场反接制动的机械特性,给出了相关电路参数计算,最后给出了改进的电路设计。现场运行结果表明这种设计具有很好的制动性能并满足安全要求。

窄巷口水电站左岸防渗线岩溶渗漏管道探测研究

本文在系统整理研究窄巷口水电站已有勘察、试验成果的基础上，通过岩溶地质分析，综合运用各种水文地质测试方法，包括水位观测、地下水温度、电导率测量和示踪试验等，研究库首左岸防渗线的地下水渗流场、温度场、电导率场等物理场，各场相互印证，并以物探和钻探等手段加以验证。在大量勘察、分析工作的基础上，掌握了左岸岩溶发育的基本规律，查明了主要渗漏管道的位置、规模和形态，为防渗堵漏处理提供了翔实的地质资料。