换流器

An input phase voltage is divided into a main range and a transition range in which new P, M, N conditions and PM, NP, MN transition conditions are defined, some null vector is selected and the condition combination sequence of bidirectional power switches are adjusted in each modulation period to realize the safe, reliable and rapid commutation and the stable operation of the matrix converter.

本发明属于矩阵变换器控制技术，为一种用于矩阵变换器的控制方法，通过把输入相电压划分为主区间和过渡区间、在过渡区间定义新的P、M、N状态和PM、NP、MN暂态以及在每个调制周期内选择特定的零矢量并调整双向功率开关状态组合顺序，实现矩阵变换器安全、可靠、快速换流和稳定运行。

The results indicate that: 1 the system can directly show the activity of fluid field and satisfy a certain need; 2 The distribution of particle concentration in pipe is unequality and the unequality degree varies with the cent of volume and regime fl...

试验结果表明：1该系统能直观显示被测流场的运动状态，满足一定流场的测量要求；2颗粒在管内的浓度分布是不均匀的，随颗粒的体积分率和流型的变化而变化；3所得的试验结果能够解释液-固流化床换热器的强化传热和防除垢机理。

Spiral baffle plate heat exchanger improved heat changing efficiency salient, reduced the press with great, control the damage from the shake, reduced the possibility of dirt subside, it has many merit.

摘要螺旋折流板换热器显著地提高了换热效率，大幅度降低了压力降，控制了振动造成的破坏，减少了污垢沉积的可能性，具有诸多优点。

Numerical controlled program was compiled with ETA code. The baffles were welded into a pile, then the holes were drilled using milling cutter and twist drill. The baffles were installed on Mitsubishi numerical controlled machine, and numerical controlled process was realized. This can improve production efficiency, which makes it possible that helix-baffled tubular heat exchangers can be widely applied in factory.

在MITSUBISHI操作系统的数控钻铣床上，采用特殊的刀具，将折流板点焊为一擦，装夹在旋转工作台上，使之与刀具成一个固定角度，实现了阶梯式螺旋折流板上孔的加工，解决了制造的难题，提高了生产效率和钻孔精度，为螺旋折流板管壳式换热器的推广应用提供了可能。

The drum,screw, screen changer and die head are made of high quality alloyed steel (38CrMOAIA) with high hardness, strong corrosion resistance and long operating life after nitrogen treatment.

螺杆、料筒、换网器、模头均选用优质合金钢（38CrMoAIA），经氮化处理，硬度高、防腐能力强、使用寿命长；模头为衣架式支管递减型，流道利于熔料流动、无滞留现象，片材厚度均匀；压光琨内采用螺旋往复式水槽，水循环冷却，效果极佳；模头、换网器、料筒温度分段控制，整机传动同步运行。

The positive converter makes the load current to be positive in trigging control, while the negative converter is negative.

系统建模在实际确定的导通模式基础上加上两管换流模式和正负换组模式；触发控制中正组变换器使负载输入电流为正，负组变换器使其为负。

Two-stage matrix converteris a novel matrix converter,which developes from conventional matrix converter.Besides of adopting many ideal characteristics of CMC,TSMC also has many other merits,such as:fewer power switchings,more simplified clamp circuit,simple and reliable inversion,much simple control strategy,etc.

双级矩阵变换器(two-stage matrix converter，简称TSMC)是一种新型矩阵变换器，它继承了传统矩阵变换器(conventional matrix converter，简称CMC)的诸多理想特性，又具有功率开关器件相对较少、箝位电路大大简化、换流简单可靠、控制算法的复杂性降低等优点。

Compared with traditional two-stream heat exchangers, multi-stream heat exchangers possess many advantages such as high efficiency, compact structure and low cost.

与双流股换热器相比，多流股换热器以其高效率、结构紧凑及投资低在气体加工和石油化工等一些过程工业中有着广泛的应用。

Although multi-stream heat exchangers are widely used in process industries such as gas processing and petrochemical industries, much work during the last two decades is focused on conventional two-stream heat exchanger networks.

但是过去的20多年里人们把大部分精力用于传统的双流股换热器网络综合的研究，有关多流股换热器网络综合问题的数学模型及求解技术研究目前仍然很有限。

So the flexible HEN problem in the low temperature processes is more evident. Most papers focus on the flexible synthesis of two-stream HEN. The research on the flexible synthesis of multi-stream HEN is limited because of the complexity of the problem and the difficulty of finding the global optimum solution.

目前大多数文献主要集中在双流股换热器网络柔性综合方面的研究，由于多流股换热器网络柔性综合问题的复杂性以及非线性数学模型全局最优解的求解难度，使得这方面的研究极富挑战性。

Neither the killing of Mr Zarqawi nor any breakthrough on the political front will stop the insurgency and the fratricidal murders in their tracks.

在对危险的南部地区访问时，他斥责什叶派民兵领导人对中央集权的挑衅行为。

In fact,I've got him on the satellite mobile right now.

实际上 我们已接通卫星可视电话了