主电流

In this paper,The necessity of frequency tracking in ultrasonic cleaning equipmens is discussed.Based on a introduction on the principle of the mian circuit of the ultrasonic power supply for cleaning equipmens and the principle of PLL ,the output frequency of 74HC4046 is changed by a singlechip measuring the phase difference between volage and current.

本文讨论了超声波清洗机中自动频率跟踪的必要性，在介绍超声波清洗机的主电路原理、PLL锁相环原理的基础上，利用单片机检测超声电源负载的电流、电压的相位差，来改变74HC4046 的输出频率，完成了变步长频率跟踪软件设计。

In this paper,the necessity of frequency tracking in ultrasonic cleaning equipmens is discussed.Based on introduction on the principle of the mian circuit of the ultrasonic power supply for cleaning equipmens and the principle of PLL,the output frequency of 74HC4046 is changed by a single chip measuring the phase difference between volage and current.The software of adaptive tracking technique with varied frequency steps is completed.

讨论了超声波清洗机中自动频率跟踪的必要性，在介绍超声波清洗机的主电路原理、PLL锁相环原理的基础上，利用单片机检测超声电源负载的电流、电压的相位差，从而改变74HC4046 的输出频率，完成了变步长频率跟踪软件设计。

The optimum bath components and operation conditions of electrodepositing Zn-Mn alloy from a sulfate-citrate bath were studied.

研究了硫酸盐-柠檬酸盐体系电沉积锌锰合金的镀液组分及工艺条件，讨论了主盐浓度、络合剂浓度、电流密度及pH等对合金镀层中锰含量的影响。

The effects of bath composition, cathodic current density and temperature of alkylsulfonate base tin-lead alloy electroplating on tin content and thickness of electrodeposits were studied through Hull cell test.

利用赫尔槽试验研究了烷基磺酸盐电镀锡铅合金工艺中电流密度、主盐浓度、游离酸浓度及温度对镀层厚度和组成的影响。

Moreover, based on small signal analysis method, the equivalent small-signal model of the main circuit is achieved, and the system transfer function is established by predigesting the double control loop to a single one. On the basis of transfer function, the frequency characteristic of the system is analyzed and the compensator is designed. Emulation results show a good dynamic characteristic of the closed system.

同时，采用小信号分析的方法，建立了开关电源主电路的等效小信号模型，并通过将电流电压双环控制系统转化为单环控制系统获得了开关电源系统的传递函数，在分析系统频率特性的基础上设计了系统的补偿器，仿真结果表明，补偿后的系统具有良好的动态特性。

In order to reduce the effect of probe errors in near-field antenna measurement, the solutions are proposed as follows: On the one hand, theoretical formula of probe-compensated is derived; on the other hand, drop-shaped probe is designed and near-zone gain, far-field patterns, axial ratio, main lobe width, input impedance, voltage standing-wave ratio, electromagnetic field and current distribution of probe are obtained through the computer simulation.

针对近场测量中的重要误差源之一&探头&的影响，本文提出解决方法：一方面用探头补偿的方法，根据洛仑兹互易定理和微波网络理论对补偿的解析式进行详细推导；另一方面用两种不同的仿真软件求解终端开口矩形波导探头的近场增益、远场方向图、轴比、主瓣宽度、输入阻抗、电压驻波比、电场分布、磁场分布、表面电流分布等特性参数，可实现探头增益的修正。

Start-up operation: Switch on the motor of the press firstly, then the feeding motor; afterwards, adjust the discharging fineness by the hand wheel and feed speed, set the current of motor in a reasonable range.

开机运作：首先启动主电机后启动送料电机，转动手轮调整出料细度，调整送料速度，置主机电流于合理范围。

A formula for short current calculation in low voltage power grid distribution was put forward.

提供了一般低压配电网主电源侧短路电流计算的公式。

Some circuits use resonant, quasi-resonant, and/or multi-resonant techniques. However, voltage or current stresses in these converters are higher and require the devices of higher VA rating. Some circuits use passive snubbers or active clamp techniques. However these converters become more complicate. Phase-shift ZVS technique has been used in bidirectional DC/DC converters since it can realize ZVS for all switches without auxiliary switches.

谐振、准谐振或多谐振技术方案，变换器的电压电流应力较高，变频控制增加了滤波器设计的难度；能量缓冲吸收电路或有源钳位电路方案，由于需要增加多个额外辅助元件，增加了变换器的复杂性；全桥相移技术方案，由于主电路无需增加额外元件，只需利用相移控制，即可实现软开关，因此引起关注。

It also proposes some suggestions on setting calculation of negative-sequence current for startup failure protection,and attentions on open phase of generator transformer unit.

通过查阅几家国内比较大的继电保护厂家的技术说明书，其中要求启动失灵保护的负序判据按照0.1～0.2倍的额定电流整定，CT取自断路器主变高压侧，再无其他要求说明。

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。