低速运动条件下的磁传感器定位方法

为了提高磁传感器定位技术的实用性,将时分复用技术应用于磁传感器的定位中,有效解决了运动磁传感器的定位问题,提出了基于磁场模值的标量定位方法,解决了背景磁异常对磁传感器定位精度的影响,并理论分析和实验验证了所提方法的可行性,实验结果表明,定位距离在3 m内时误差在厘米级别,并有望随实验条件的改善而提高,且该方法定位的灵敏度非常高。     

±800kV特高压换流站换流阀BOD动作导致阀组闭锁故障分析处理及优化

2014年4月8日,西北某特高压换流站极Ⅱ高端换流阀阀控主机CCPB切至主用状态时,由于极Ⅱ高端阀组换流阀控制单元VBE的B系统满足单晶闸管冗余跳闸条件(保护性触发大于3个跳闸),造成极Ⅱ高端阀组闭锁及功率转带成功,但未造成功率损失。本文首先介绍了换流阀阀控及流阀保护性触发(BOD)动作原理。其次详细说明该换流站发生换流阀BOD动作事件以及通过现场检查及试验排查的方法对故障进行分析处理方法,发现换流阀BOD动作逻辑和控保软件切换逻辑不合理。最后针对这两种不合理问题,提出相应的优化建议,避免后续工程出现类似问题。     

A finite pointset method for the numerical simulation of free surface flow around a ship

In this paper, we present a Finite pointset method (FPM) for the numerical simulation of free surface flow around a ship in calm water. It is a Lagrangian and meshless particle scheme which is applied to the projection method for the incompressible governing equations. This requires the solution of Poisson problems in each time step, so a moving least squares (MLS) interpolants is used for the spatial derivatives in order to discretize the Poisson equation with pressure-Dirichlet condition of free surface flow in meshless structure. Meanwhile, an additional problem of the periodic particle locations redistribution in the present approach is still handled by MLS interpolants. With the proposed FPM technique, problems associated with the free surface flow around a ship are circumvented. A verification of numerical modeling is made using the Wigley hull and the validity of the proposed methodology is examined by comparing the detail of wave profile and wave-making resistance with Series 60 model. The results demonstrate that FPM is able to perform efficient and stable simulations of free surface flow around a ship.     

Motion response prediction by hybrid panel-stick models for a semi-submersible with bracings

A diffraction-radiation analysis is usually required when the hydrodynamic interactions between structural members occur in short waves. For bracings or small cylindrical members, which play important roles in the vicinity of the natural frequency of a floating platform, special care should be taken into account for the effect of viscous damping. Two hybrid panel-stick models are, therefore, developed, through the combination of the standard diffraction-radiation method and the Morison’s formulae, considering the effect of small members differently. The fluid velocity is obtained directly by the panel model. The viscous fluid force is calculated for individual members by the stick model. A semi-submersible type platform with a number of fine cylindrical structures, which is designed as a floating foundation for multiple wind turbines, is analyzed as a numerical example. The results show that viscous force has significant influence on the hydrodynamic behavior of the floating body and can successfully be considered by the proposed hybrid models.     

船舶超载调查的误区及正确方法

本文简要介绍了在船舶超载调查中容易出现的三个误区,并对其产生的原因加以分析。结合实际工作,笔者给出了解决问题的正确方法。     

电信计费模型的设计

依据电信计费系统存在的问题,本文详细描述了电信计费模型的设计方法和各个模块的设计内容。     

基于μC/OS-Ⅱ的电力负荷控制终端的设计与实现

本文以高性能的32位嵌入式ARM芯片为处理器,结合嵌入式实时操作系统μC/OS-Ⅱ,设计和实现了实时性强、结构优化的电力负荷控制终端。构建了嵌入式系统软硬件平台,详细阐述了应用软件的任务设计、优先级安排和各任务之间的关联性,由此设计的系统性能良好,稳定可靠。     

利用稳定系数法估计电机的寿命

工程实践认为,电机的寿命主要取决于绕组绝缘的寿命.本文介绍一种利用电机绕组绝缘变化状况预测电机寿命的方法-稳定系数法,为电机的绝缘诊断和维护保养提供重要的依据.     

浅谈船舶减摇鳍的配置

该文通过对船舶减摇鳍原理和形式的介绍,并对两种减摇鳍进行对比,以期为减摇鳍的配置提供有益的参考。     

高原多年冻土区路基的施工技术

本文阐述高原地区冻土的工程特性,介绍了在特殊的多年冻土施工环境中路基工程施工的一些加强措施,并就施工中需要注意的一些问题提出见解。