电机电气控制线路的电流导向法

用传统的电气控制分析方法很难准确把握各低压电器的动作信息和动作过程，从而给分析控制线路的。针对此问题，从控制线路的基本原理出发，利用电流在线路中的流向为导向，给出了电流导向法的定义，构造了2类电流导向法的分析方法，归纳出相应的电流导向法一般步骤。由这些方法可以准确地掌握分析电气控制线路。最后，简述了电流导向法的优点，并就相关问题进行了讨论。

电机电气控制线路的电流导向法

电机电气的控制线路由三相交流电动机与低压电气组成,采用电流导向法对其进行分析,可以更好的把握低压电气动作过程。本文首先对电机电气控制线路的电流导向法相关概念进行介绍,进而分析电流导向法在电机电气控制线路中的具体应用,主要以电动控制线路和正反转控制线路为例,研究其分析流程和主要步骤。

试述电机电气控制线路的电流导向法

用传统的电气控制分析方法很难准确把握各低压电器的动作信息和过程,从而给分析控制线路带来问题,因此,从控制线路的基本原理出发,利用电流在线路中的流向为导向,给出了电流导向法的定义,构造了2种电流导向法的分析方法,归纳出相应的电流导向法一般步骤,简述了电流导向法的优点,并就相关问题进行讨论。

电机电气控制线路的电流导向法

电机电气控制线路主要由三相交流电机和低压电气两部分组成。将电流导向法作为理论依据,深入分析电机电气相应的控制线路,能够良好把握低压电气涉及的相关动作具体过程。基于此,阐述电机电气相应的控制线路和电流导向法的相关概念,分析电流导向法的具体应用情况,并结合电动控制线路和正反转控制线路两个案例,介绍电流导向法涉及的相关流程及具体步骤。

电流导向法在《汽车电气设备》课程教学中的应用

汽车电气设备是汽车的重要组成部分。随着电子技术的迅猛发展,汽车电气设备日益更新,汽车电气系统也日趋复杂,加上多数技校生基础都比较薄弱,使得《汽车电气设备》课程的教学难度也在不断地加大。为使多数基础薄弱的学生能更高效地学习并掌握汽车电气设备的知识,我们迫切需要一种适合当代技校生学习的教学方法。本文阐述的电流导向法是一种水到渠成的教学方法,具有事半功倍的效果。

Electrical conductivity effect on MHD mixed convection of nanofluid flow over a backward-facing step

In this study,magneto-hydrodynamics (MHD) mixed convection effects of Al2O3-water nanofluid flow over a backward-facing step were investigated numerically for various electrical conductivity models of nanofluids.A uniform external magnetic field was applied to the flow and strength of magnetic field was varied with different values of dimensionless parameter Hartmann number (Ha=0,10,20,30,40).Three different electrical conductivity models were used to see the effects of MHD nanofluid flow.Besides,five different inclination angles between 0°-90° is used for the external magnetic field.The problem geometry is a backward-facing step which is used in many engineering applications where flow separation and reattachment phenomenon occurs.Mixed type convective heat transfer of backward-facing step was examined with various values of Richardson number (Ri=0.01,0.1,1,10) and four different nanoparticle volume fractions (Ф=0.01,0.015,0.020,0.025) considering different electrical conductivity models.Finite element method via commercial code COMSOL was used for computations.Results indicate that the addition of nanoparticles enhanced heat transfer significantly.Also increasing magnetic field strength and inclination angle increased heat transfer rate.Effects of different electrical conductivity models were also investigated and it was observed that they have significant effects on the fluid flow and heat transfer characteristics in the presence of magnetic field.

Electrophysiological study on differentiation of rat bone marrow stromal stem cells into neuron-like cells in vitro by edaravone

Objective： To explore the electrophysiological proper- ties of differentiation of rat bone marrow-derived stromal stem cells （rBMSCs） to neuron-like cells in vitro by edaravone, a new type of free radical scavenger. Methods： Stromal stem cells were separated from rat bone marrow with Ficoll-Paque reagent and expanded in different culture medium in vitro, rBMSCs were induced by edaravone containing serum-free L-DMEM. Morphologic observation and Western blot analysis including the expression of Nav1.6, Kvl.2, Kv1.3, Cav1.2 were performed, and whole patch-clamp technique was used. Results： Cyton contraction and long processes were shown in differentiated stromal stem cells. Navl.6, Kvl.2, Kv 1.3 and Cav 1.2 were expressed in both differentiated and undifferentiated ceils. However, the expression of channel proteins in differentiated cells was up-regulated. Consistently, their resting potential and outward currents were also enhanced in the differentiated cells, which was especially significant in the outward rectifier potassium current. Conclusion： In vitro, neuron-like cells derived from rBMSCs, induced by edaravone, possess electrophysiological properties of neurons.

Experimental study of the effects of a transversal air-flow deflector in electronics air-cooling

This paper presents an experimental investigation of the influence of a transversal flow deflector on the cooling of a heated block mounted on a flat plate.The deflector is inclined and therefore it guides the air flow to the upper surface of the block.This configuration is simulating the air-cooling of a rectangular integrated circuit or a current converter mounted on an electronic card.The electronic component is assumed dissipating low heat power,as such,air forced convection is still a sufficient cooling way even without fan or heat sink on the component.The measurements are given by hot and cold wires anemometers and by an InfraRed camera.The results give details of the effects of the deflection on the hydrodynamic and the thermal fields on and over the block for different inclination angles.They show that the deviation caused by the deflector may significantly enhance the heat transfer from the component.Deflection is also able to avoid local overheating of the electronic component.Optimum heat transfer rate and homogenised temperature are shown to be obtained with an inclination angle =30°.