恒流

What this paper finished mainly work as follows: Five-phase hybrid step motor driver system with fixed-chopping frequency and constant total current driving is fully described. Mathematical model of the system, included the current control circuit, power driving circuit and five-phase hybrid stepping motor is established. The steady modeling of the system is established and studied. Based on the steady modeling of the system, dynamic modeling of the system is studied and single step response characteristic is constructed with MATLAB/Simulink. The simulation results, which is certified by the theory analysis, coincide with the theory analysis.

本文主要完成的工作包括几个方面：对五相混合式步进电动机恒频斩波恒总流驱动系统进行了完整的描述；建立了包括电流控制电路、功率驱动电路以及五相混合式步进电动机在内的恒频斩波恒总流驱动系统的完整的数学模型；基于MATLAB/Simulink建立了恒频斩波恒总流驱动系统稳态仿真模型，并进行了仿真；在建立其稳态仿真模型的基础上，对动态模型进行研究，并借助于MATLAB/Simulink工具建立了恒频斩波恒总流驱动系统单步响应特性的仿真模型并对其单步响应特性进行了仿真研究，仿真结果与理论分析相符。

Seepage velocity smoothly change from a steady value to a new steady value, the ratio of the new steady value over the original steady value might increase hundreds of thousand times or even more, but it is always finite.（3）Water-inrush goes with the failure of rock strata, but seepage velocity can not increase unendingly, so seepage flow cant be unstable.

研究表明：由于非Darcy流β因子恒为正值，渗流系统总是稳定的；当渗透特性随时间变化时，渗流速度从一稳定值平滑地过渡到一新的稳定值，新的稳定值与原稳定值之比可以增大到几万至几百万倍，但是总是有限的；突水是岩层结构破裂引起的渗流速度快速或急剧变化，但渗流速度不可能无止境地增大，即渗流不可能失稳。

The results indicate that in the synchronizing condition the MRF is unyielded, every point of MRF in the flow field has the same angular velocity. Under the slipping condition, with the increase of magnetic field or the decrease of slip speed, MRF may transfer from whole yield to partial yield. When the MRF wholly yields, the angular velocity of MRF increases nonlinearly with its radius, the non-linear distribution becomes more obvious as the magnetic intensity in the working gap increases. When the MRF partially yields, the yield region expands with the decrease of magnetic intensity or the increase of slip speed and the unyield region always reaches the driven rotor. The transfer torque of MRTD increases with the increase of the external magnetic field, but the transfer torque maintains a constant value approximately with the variation of slip speed at the same magnetic intensity.

研究结果表明，在同步工况下，传动装置流场中磁流变液未屈服，各点角速度相同；在滑差工况下，随外加磁场的增大和滑差转速的减小，磁流变液逐渐从完全屈服向部分屈服转变；磁流变液完全屈服时，磁流变液角速度随半径呈非线性增加，工作间隙中磁场越强，流场的非线性分布越明显；磁流变液部分屈服时屈服区域随外加磁场的增大而减小，随滑差转速的增大而增大，未屈服区与主动转子相连；稳态下磁流变传动装置传递的转矩随外加磁场的增加而近似呈线性增大，但在相同外加磁场下，传递转矩基本不随滑差转速改变而改变，表现出良好的恒转矩特性。

Comparing comprehensive ly the present various current converting circuits, it is proposed an design structure of direct-driven wind power generation current converting systems in megawatt level.

摘 要：在综合比较当前适合直驱型风力发电机组的各种变流电路的基础上[1~ 2]，提出了一种兆瓦级直驱型风力发电变流系统的设计结构，即采用不控整流+升压斩波+SPWM逆变的变流器将电机发出的电能转换为可接入电网的恒频恒压的交流电。

We adopt nine-point control theory to design software which is mostly fit for limiting current start mode.

主要针对恒流起动方式进行了软件设计，采用了九点控制思想。

Which provides theoretic foundation for confirming the working situation of constant current tube.

为确定恒流管的工作状态提供了理论依据。

The electrochemical capacitance performance of the composite was investigated by cyclic voltammetry and galvanostatic charge-discharge tests with a three-electrode system in 10 wt% H2SO4 solution.

在10wt%硫酸为电解质溶液的三电极体系中，采用循环伏安和恒流充放电技术测试了复合材料的电化学电容性能。

The result of testing on site manifests that the effect of spot welding constant current control is good.

实际焊接考核试验结果表明：控制系统具有很好的恒流控制效果。

Carbon micro-coils were modified with ruthenium oxide(RuO2) by gel method,the RuO2/carbon micro-coils electrodes were prepared and button type supercapacitors were assembled.

利用凝胶法在碳微线圈上进行氧化钌(RuO2)修饰，制备RuO2/碳微线圈电极，组装成纽扣式超级电容器，比较了两种电极材料的循环伏安及恒流充放电特性。

AIM: To study the mechanism and implementation of current pulse exciting impedance measurement of bio tissues.

为减少皮肤电极接触阻抗、极化电势所引起的伪差，实际应用中多采用正弦波恒流源激励［2］。

I'm strongly against the death penalty — it's an eye for an eye.

我不赞成死刑——这是以牙还牙的报复行为。

And to get you the support you need, we're enlisting all elements of our national power: our diplomacy and development, our economic might and our moral suasion, so that you and the rest of our military do not bear the burden of our security alone.

并给你们所须的支援，我们正徵召国家所有各种的力量：我们的外交及发展，我们的经济力量与道德劝说，所以你们与其他军人不须要孤独地负起国家安全的责任。