协变和逆变的区别对于张量的计算尤为重要，这往往会出现混合方差。
The distinction between covariance and contravariance is important for computations with tensors, which often have mixed variance.
最后就是对协变和逆变的支持了。
管逆变工作频率高，高效，低噪声。
V-MOS inverter high running frequency, high efficiency, low noise.
逆变焊机取代传统焊机已成为必然趋势。
Inversion welder replace traditional welder have become inevitable tendency.
将直流变为频率可调的交流电流就称逆变。
The DC into AC current adjustable frequency that the inverter on.
介绍了该逆变式弧焊机的构成，工作原理及特点。
The paper introduces the configuration, principle and characteristics of the inverter for arc welder.
采用IGBT逆变技术，大大提高了整机可靠性。
Adopt inverter IGBT technology, the reliability of the machine greatly improved.
产品详述采用IGBT高频逆变，体积小，重量轻。
The use of high frequency IGBT inverter, small size, light weight.
伏能士知道如何降低这些费用的答案—有源逆变技术。
Fronius has the answer to the problem of how to lower these costs - Active Inverter Technology.
本文采用双逆变技术研制了一种新型的焊接磁搅拌装置。
A new welding electromagnetic stirring device was developed with the dual inverter technique in this paper.
本文介绍一种应用于IGBT逆变式点焊机的点焊控制器。
A controller applied to IGBT inverter spot welding machine is introduced in this paper.
本文简单介绍了线型调制器谐振式逆变充电电路的工作原理。
The paper introduces simply the operational principle of the resonant invert charging circuit of line-type modulator.
CIT系列逆变充电器是采用先进的逆变技术开发的新产品。
CIT inverter charger is the new-developed product with the advanced inverter tech.
本文介绍了电力行业在逆变焊机选型工作中的一些做法和原则。
Some methods and Principles of inverter welding machine type - Selecting in power trades are introduced in this article.
采用先进的逆变技术，工作频率高，体积小，重量轻，便于携带。
The use of inverter technology, high frequency, small size, light weight, easy to carry.
采用先进的逆变技术，工作频率高，体积小，重量轻，便于携带。
Adopt advance inverter technology, with high working frequency; lt's compact, light, easy to carry.
设计了一种集充电和逆变功能于一体的大功率光伏逆变电源系统。
A kind of high power photovoltaic inverter power system, containing charge and inversion function is designed.
提出采用大功率IGBT设计变极性脉冲MIG焊双逆变弧焊电源。
The high-power IGBTs are adopted to design the dual inverter arc-welding power source for variable polarity pulse MIG welding.
结果表明：这种新型的大功率埋弧逆变自动焊机有着广阔的应用前景。
The result shows that this newfashioned high-power machine of submerged-arc welding inverter has wide prospect of application.
本文介绍了逆变式等离子弧切割机的工作原理、使用方法和维修措施。
The principle, operation and repair of invert plasma are cutting machine are introduced in this paper.
本文论述了可控硅逆变器逆变角影响串级调速装置功率因数的基本原理。
This paper discusses the basic principle which the inverted firing angle of thyristor inverter has the influence on power factor of a cascade connected device.
这些引弧器的应用对于提高逆变焊机的引弧性能、可靠性等有较大的益处。
These arc strikers are of value for improving arc strike behaviour and reliability of invert welding power sources.
用于抽水蓄能机组起动的静止变频器，其整流逆变桥通常采用普通晶闸管。
The static frequency converter used in pumped storage units generally adopts common thyristor as the rectifying inverting bridge.
本论文主要介绍了所研制的单片机控制逆变埋弧焊机的组成结构和控制原理。
The component parts and control principle of pulsed SAW inverter power source are mainly introduced in the paper.
系统以SPMC75 F 2413 A作为主控芯片来控制单相桥式逆变主电路。
The SPMC75F2413A chip is used as main control chip to control single-phase bridge inverter main circuit.
以应用于燃料电池逆变功率变换的阻抗源逆变器为例，分析了其工作原理和控制方法。
To describe the operating principle and control, this paper focuses on an example: a Z-source inverter for dc-ac power conversion needed in fuel cell applications.
该系统包含升压和逆变两个环节，均采用电压外环、电流内环的双环pwm控制方式。
The two parts both adopt double loop PWM control mode which consists of outer voltage loop and inner current loop.
SVPWM具有较高的直流电压的利用率，开关损耗小，从而实现了高性能的逆变输出。
SVPWM technique have many good qualities, such as less pulsating torque, high usage of DC bus voltage, less switching loss, better high-speed regulation performance.
比较电压偏差及其变化率，查询模糊控制表，调节逆变脉宽，可实现电压及电流的理想控制。
According as compare of voltage deviation and its variable ratio, optimal control of voltage and current is realized with querying fuzzy control sheet and adjusting adverse variable pulse width.
注意尽管上面的例子只展示了对于代理类型如何声明协变和逆变。对于接口这样做也是不难的。
Note that although the above examples show how to declare covariance and contravariance for delegate types, it's not different to do so with interfaces.
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