查询词典 direct current

The main research work of this dissertation is as follows: Based on the chemical reaction engineering theory and the nitrobenzene electroreduction mechanism, the plate and frame electrolyzer was designed and applied to the process of electroreduction nitrobenzene to p-aminophenol. This dissertation measured the residence time distribution data of the electrolyzer by means of the pulse response method and studied the rule of flow pattern along with the current capacity change. Under different conditions ,this dissertation studied the cyclic voltammetry properties of nitrobenzene on different electrodes by means of the dynamic cyclic voltammetry method and the electrode materials applied to the NB electroreduction have been selected primarily.Baseed on the results of cyclic voltammetry tests, this dissertation used p-electrode systems to measure the steady-state- polarization curves of nitrobenzene on different electrodes in H-type diaphragm cell, and obtained each primary factor s influence rule and the exchange current density value of each electrode.And then on the basis of the conclusions of fundamental researchs upword, the effects of influence factors on the the yield of p-aminophenol and the current efficiency,such as electrode material, current density, quantity of electricity circulated, nitrobenzene concentration . sulpuric acid concentration and so on, have been studied in detail in the systems of hign temperature , strong acidity and oxygen-poorthrough a series of electrolysis experiments in this paper.After all using Pb as anode Monel metal as cathode Dupont Nafion 417 cation-exchange membrane as membrane, this dissertation obtained the optimum technological condition: reaction temperature about 85C, current density 500A m-2, sulphuric acid concentration 20%wt.

论文的主要研究工作为：运用化学反应工程理论，结合硝基苯的电还原机理，设计出用于硝基苯直接电还原合成对氨基苯酚实验的板框式电解槽，并利用脉冲响应法测定了该板框式电解槽的停留时间分布数据，研究了流型随流量变化的规律；通过动态循环伏安法研究了硝基苯在不同电极上、不同条件下的循环伏安特性，初步评选出了用于硝基苯电还原的电极材料；结合循环伏安的测定结果，在H型隔膜电解槽中采用三电极体系测定了硝基苯在不同电极上、不同条件下的稳态极化曲线，得到了各主要因素的影响规律及硝基苯在各个电极上电还原的交换电流密度数值；在基础研究结论指导下，采用板框式电解槽，在高温、强酸、贫氧系统中，进行了一系列的电解实验，分别考察了电极材料、电流密度、通电量、硝基苯浓度、硫酸浓度等因素对收率及电流效率的影响，最终选择以蒙乃尔合金电极作为阴极、铅合金为阳极、Dupont Nofion 417阳离子交换膜为隔膜，得到由硝基苯直接电还原制对氨基苯酚的最佳电解工艺条件：反应温度85℃，电流密度500A·m~(-2)，硫酸浓度20％wt。

The utility model relates to a double-purpose driving apparatus of medical X-ray machine with remote-control and direct-control, which belongs to medical equipment.The driving apparatus comprises a direct-current speed reducing motor whose output terminal is fixed with a ring electromagnet; an armature iron is arranged on the motor output shaft whose end is provided with a driven wheel meshes with the armature iron and rotates around the motor shaft.As the electromagnet is electrified, the armature iron is attracted and disengages from the driven wheel.With the driving apparatus, the remote control and the direct control of a non-remote controlled X-ray machine can achieve, increasing the working efficiency by 3 to 4 times and the economical benefits.

该实用新型涉及双重用途的驾驶仪器的医用X光机的远程控制程序，并进行直接控制，属于医疗equipment.the驾驶仪组成，直接电流减速电机，其输出端是固定的一个环电磁铁；电枢铁是安排在电动机输出轴，其终点就是提供一台四轮驱动的网格与电枢铁和周围旋转电机shaft.as电磁铁通电，电枢铁是吸引和脱离接触，从驱动轮随着驾驶仪器，远程控制，并直接控制的一个非遥控X光机，能做到的事，提高工作效率3至4倍和经济效益。

Then, after introducing the direct current sensitivity analysis method of general ATC, the direct current sensitivity analysis method of blind number ATC is studied, and some predigestion tips are also proposed to decrease computational effort.

以确定性可用输电能力的直流灵敏度分析法为基础，提出盲数ATC的直流灵敏度算法，并给出盲数运算的简化处理方法。

Traditional instrument in harmonic measurement is the transformer with circularity form core coil, but it is influenced by direct current and saturated, so it could not be used to measure direct harmonic current.

基于Rogowski 线圈的光电直流谐波电流测量系统解决了传统谐波电流测量受直流分量影响的难题，是集光纤技术、电子技术、激光技术于一体的新型谐波电流互感器。

This task designs a regulated power supply of direct current with numerical control and numeric display, this power supply includes the modular circuit of direct current of stabilized voltage, protective circuit modular and voltage adjust modular etc.

中文摘要该课题设计一个数控数显直流稳压电源，该电源包括直流稳压电路模块，电压调整电路模块和保护电路模块等部分组成。

A blend closed loop control system is introduced,which is constituted with microcontroller,photoelectric coder,direct current servo electromotor and direct current servo electromotor drivers.

本设计要求对某火炮的水平和高低角进行控制，达到快速位置伺服系统的要求。

Based on the present conditions in this field all over the world, this dissertation detailedly analysed the working process of the reversible direct current PWM controlled by double poles bridge, and illustrated the merits and shortcomings of the direct current PWM system.

本文针对国内外在这一领域的研究现状，详细分析了双极式控制的桥式可逆直流脉宽调速系统的工作过程，以及直流PWM系统的原理和优缺点。

This protection machine series product make use of to respond to quickly not the line presses the component , assurance the direct current system is positive, the anode, cathode and as and anodes and the potential difference of the as settle, allowing appear temporary in the direct current system conduct electricity press limit the weak electricity equipments inside the scope, thus insuring the equipments safety movement.

本保护器系列产品利用快速响应的非线性压敏元件，保证直流系统正、负极间，正极与地间及负极与地间的电位差恒定，将直流系统中出现的暂态过电压限制到弱电设备的允许范围内，从而确保设备安全运行。

Sensor less blushless direct current motor is the prospect of brushless direct current motor, however, the key factors which rotor position estimation can be diffcultly gotten at standstillor low speed limit brushless motors use.

无位置传感器无刷直流电机是无刷电机的发展方向。

The DC generator produces multiphase alternating currents in its armature windings, and a commutator on the armature shaft converts these alternating currents into a direct current output; or a homopolar generator produces a direct current without the need for a commutator.

直流发电机出示其骨架绕组多相交流电流和电枢轴上的一个换向器将这些交流电流转换成直流电流输出；或 homopolar 发电机一直流电流，而无需一换向器。

Bob Eckert has been chairman and chief executive of Mattel for eight years.

美泰董事长兼首席执行官鲍勃·埃克尔特在任已8年。

The outlook for honors and disgraces carries on and surpasses the traditional outlook for honors and disgraces theoretically, and carries on and develops the theory of construction of socialist mora...

社会主义荣辱观的提出在理论上是对传统荣辱观的一次继承和超越，是对社会主义道德建设理论的继承和发展，在实践上有利于形成良好的社会风尚。