变变

For detecting the vibration frequency the dynamic systems, and using topology contravariant functor the unknown space was mapped to known space,the vibration frequency of unknown space will be investigated by the contravariant functor.

为了分析动力系统振动频率的瞬变性，采用拓扑反变的理论把未知的动力系统空间映射到已知的空间中，通过拓扑反变算子研究未知的空间频率的瞬变性。

Every vector can be resolved into covariant or into contravariant components.

每个矢量都可以分解成协变分量或逆变分量。

The present paper proposed one kind of numerical control single-phase inversion structure, in detail elaborated the system parameter design, the rectification work basic principle of work, the contravariant basic principle and the SPWM sine pulse width modulation.

本论文提出了一种数字控制的单相逆变器结构，详细论述了系统的参数设计，整流工作的基本工作原理，逆变的基本原理及SPWM正弦脉冲宽度调制。

Because contravariant redefinition of method is not consistent with traditional programming style, covariant redefinition of method is preferred to as the mechanism to support specialization.

反变的方法重定义不符合思维习惯，一般采用协变精化的设计方法。

This article introduces a new contravariant bridge circuit in the power source of the medium friquency induction furnace,analyzes the necessity of using R-C for protecting the thyris-tors.

介绍一种新型晶闸管中频感应电炉的逆变电桥，分析了对该电桥逆变晶闸管采用阻容保护电路的必要性。

Along with the electrical machinery control special-purpose DSP appearance and the control theory universal development, caused the contravariant power source the control technology to face the entire digitized, the intellectualized direction is developing, inverts the power source numerical control technology to have a big leap.

随着电机控制专用DSP的出现和控制理论的普遍发展，使得逆变电源的控制技术朝着全数字化、智能化的方向发展，逆变电源的数字控制技术发生了一次大的飞跃。

The presentpaper proposed one kind of numerical control single-phase inversionstructure, in detail elaborated the system parameter design, therectification work basic principle of work, the contravariant basicprinciple and the SPWM sine pulse width modulation.

本论文提出了一种数字控制的单相逆变器结构，详细论述了系统的参数设计，整流工作的基本工作原理，逆变的基本原理及SPWM正弦脉冲宽度调制。

It when the contravariant power source works the continually output is 100W, may realize the power source to invert, functions and so on voltage regulation, undervoltage protection and overflow protection.

其在逆变电源工作时的持续输出功率为100W，可实现电源逆变、电压稳定、欠压保护及过流保护等功能。要准确的，不要在线翻译了给我，谢谢了

We use integrated chip TL494 are the master control chips, by the MOSFET tube constitution inversion electric circuit, has realized the contravariant system's pulse-duration modulation.

我们采用集成芯片TL494为主控芯片，以MOSFET管构成逆变电路，实现了逆变系统的脉宽调制。

The 300W single item incorporation feed inversion electric circuit's design is mainly transforms the small electro-optical source battery through the contravariant electric circuit as the stable room electric output.

300W单项并网馈电逆变电路的设计主要是将小型的光电源电池通过逆变电路转化为稳定的室电输出。

However, as the name（read－only memory）implies, CD disks cannot be written onorchanged in any way.

然而，正如其名字所指出的那样，CD盘不能写，也不能用任何方式改变其内容。

Galvanizes steel pallet is mainly export which suits standard packing of European Union, the North America. galvanizes steel pallet is suitable to heavy rack. Pallet surface can design plate type, corrugated and the gap form, satisfies the different requirements.

镀锌钢托盘多用于出口，替代木托盘，免薰蒸，符合欧盟、北美各国对出口货物包装材料的法令要求；喷涂钢托盘适用于重载上货架之用，托盘表面根据需要制作成平板状、波纹状及间隔形式，满足不同的使用要求。