主电流

In order to study the primary resonance and primary parametric resonance of current-carrying conductor subjected to harmonic excitation and ampere force, the Mathieu-equation of the system is derived first.

研究受简谐激励的二长直电流间载流导线的主共振主参数共振问题，应用动力学方法建立载流导线受外部激励和安培力的Mathieau方程。

The present magnetic resonance electrical impedance tomography method can only be used in MRI systems in which the main magnetic fields are parallel to the horizontal plane. In this paper, a new MREIT method with currents injected from an oblique plane is proposed. It can be used on MRI scanners with either permanent magnet or superconductive magnet.

现有的磁共振电阻抗成像方法只适用于主磁场平行水平面的磁共振系统，本文中提出了一种新的MREIT方法即斜位电流注入磁共振电阻抗成像，同时适用于主磁场垂直于水平面的磁共振系统。

A detailed analysis of the main circuit introduction, control method and working principle of the direct-drive wind energy conversion system are given to introduce the two important parts a of this paper: First part is the control method of the multiple boost convertor, the important instantaneous current control method of this paper is given through the analysis of the main circuit structure, control method and working principle. Then a steady-state analysis for low-frequency, a high-frequency component analysis, and a closed-loop tracking performance analysis for dynamic response are provided to analyze the method proposed; And the second part is the control method of invertor.

在系统变流器整体结构分析的基础上，引出本文重点研究的两个变流环节的控制：第一部分是系统升压斩波器的控制，通过分析相关主电路结构、原理，建立了数学模型，引出本文重点研究的瞬时值控制策略的概念和具体实现，并对升压斩波器的瞬时值控制策略进行了详细的高频、低频模型分析和稳态、动态性能分析；第二部分是系统并网逆变器的控制，通过对逆变器主电路的数学建模和控制要求分析，研究了并网逆变器的瞬时值控制策略，包括电感电流控制内环和直流电压控制外环的具体设计和实现方法。

In order to solve the current differential protection's maloperation, the combined harmonic blocking criteria and the criteria based on the trace of action point are proposed.

电流互感器发生暂态饱和时，二次电流中的谐波主要是2次谐波，3次谐波含量很少。

The proposed inverter has a new auxiliary resonant commutation cell. It provides that all main switching power devices in the soft-switching inverter operate at zero-voltage-switching turned-on and the auxiliary switches operate at zero-current-switching turned-off. In addition, this thesis presents an improved control scheme to minimize the operation of auxiliary resonant circuit for efficiency improvement.

所研制之柔切式数位变流器，系利用新型辅助谐振单元，使主功率开关操作於零电压切换，辅助开关操作於零电流切换，在此也提出改善之控制方案，以避免多余的辅助开关切换，因此能有效降低谐振电流所造成的额外导通损失，以提升系统之效率。

The paper focuses on realizing the monitoring system for the main insulation and restrictive coating insulation of high voltage power cables without changing the network structure of power system by measurement of phase ground current and total ground current of split phase shield cable.

重点是研究如何通过对分相屏蔽电缆的各相接地电流和总接地电流的在线监测，达到在不改变电力系统原有接线方式的前提下实现对电缆主绝缘和外护套绝缘的在线监测的目的。

To obtain lower voltage (400kV) and higher current density (143A.cm-2) for the optical aperture (φ12cm) and required laser output energy (40J) the diode separator structure in the vacuum side, electrode form, length of drift space, Hibachi open area, etc. are considered.

针对低电压(400kV)和高电流密度(143Acm－2)，重点考虑了二极管真空绝缘界面、电极结构、漂移区长度和主膜支撑等问题并介绍了实验结果：二极管电压在 450 kV以上仍能稳定工作，电流上升前沿约20ns，电子束总束能4.2kJ以上。

The objective of design optimization for the current loop is to maximize the cross-over frequency. The results show the stability is improved and the capability of suppressing the switching noise is far better than the original. The objective of design optimization for the voltage loop is to minimize the gain of the line ripple voltage.As a result the bandwidth minishes obviously and optimization design excelles in restraining the ripple.

主电路以总体积最小为优化目标，优化结果表明电路的体积减少了0.5%；电流环以开环穿越频率最大为目标，优化结果表明电流环的稳定性能得到了改善，开关噪声抑制能力明显优于优化前的；电压环以线纹波电压增益最小为目标，优化结果表明电压环的带宽明显减小，纹波抑制能力远远优于优化前的。

First, we introduce the principle of feeder protective apparatus and select adequate protective equipments in accordance with different types of distribution system, using the least square error method to simulate the time/current curve and applicate simulation formula to digital the curve data, Secondary, using augmented incidence matrix method to find the exact pairs of primary/backup protection relay and find the relay tripping sequence of distribution lines.

首先介绍线路之过电流保护设备动作原理，依不同之配电系统型态来选用适当之保护设备种类，并使用最小平方误差法模拟保护电驿之时间－电流特性曲线，应用模拟方程式将曲线之资料数位化，且藉由图形理论中之增广关联矩阵法求取正确之主保护与后卫保护电驿对，以找出系统中各配电线路保护电驿间之跳脱顺序关系。

Then compare the5 drafts from these aspects such as reliability, flexibility andeconomy, and keep two more reasonable plans than others. The shortcircuit current calculation is carried on.. And main electricequipments including circuit breakers、disconnectors、bus、insulatoretc are choosed according to the result of short circuit currentcalculation. Finally the economy of these two plans are comparedand main electrical connection plan is determined.

然后对这五种方案进行可靠性、灵活性和经济性比较后，保留两种较合理的方案，对这两种方案进行短路电流计算；接着是根据短路电流计算结果进行主要电气设备的选型以及校验，包括断路器、隔离开关、母线、绝缘子等；最后再由经济性比较确定最终的电气主接线方案。

With Death guitarist Schuldiner adopting vocal duties, the band made a major impact on the scene.

随着死亡的吉他手Schuldiner接受主唱的职务，乐队在现实中树立了重要的影响。

But he could still end up breakfasting on Swiss-government issue muesli because all six are accused of nicking around 45 million pounds they should have paid to FIFA.

不过他最后仍有可能沦为瑞士政府&议事餐桌&上的一道早餐，因为这所有六个人都被指控把本应支付给国际足联的大约4500万英镑骗了个精光。