换相

The converter combines the advantages of the PWM technique and soft-switching technique, the PWM is effected all over the whole loads range, and soft-switching is effeted only in the switching transition period, the ZVS of leading-leg is achieved by using the energy stored in leakage inductor of the transformer and the output inductor, the ZCS of lagging-leg is achieved by using a blocking DC capacitor, the ZVS and ZCS are achieved for the whole load ranges (5A~250A).

控制电路采用相移控制方式，综合了PWM控制和软开关技术的优点，在大范围内实现PWM控制，而在功率器件换流期间实现软开关换流，其中超前桥臂利用变压器的漏感，实现了零电压开关，滞后桥臂利用隔直电容，实现了零电流开关，并且整个变换电路能在（5A~250A）的范围内实现软开关工作条件，满足弧焊电源负载变化大的特点。

One or both of transmit and receive aperture controls may include preventing some element of the transducer array from transmitting or receiving, calculating weighting apodizations to combine with standard apodizations for each frame, or determining an aperture size based on an f-number for the transducer array for each frame.

发射和接收孔径控制中的一个或二者可以包括：阻止换能器阵列中的某个元件进行发射或接收，针对每一帧计算加权变迹以将其和标准变迹相组合，或者针对每一帧根据换能器阵列的F数来确定孔径尺寸。

The researches for investigating the influence of the inlet structure of the heat exchanger for two-phase flow on vapor-liquid maldistribution are reviewed.

介绍了低温两相流板翅式双相变换热器的结构和特点，回顾了板翅式换热器两相流体入口分配结构对其气液分配特性的影响。

Based on the analysis of physics course of heat transfer, the mathematical model of single-phase flow in the rectangular narrow channel is proposed. And the boundary conditions are given to get the unique numerical result. The finite volume method is used to found the discrete scheme of equations. According to the flow of SIMPLER arithmetic, the computing program is developed and the correctness of program is validated.Then the program is used to solve the problem of flow and heat transfer in rectangular narrow channel.The stable two dimension velocity and temperature fields in rectangular narrow channel and plate fuel are obtained.

在明确窄缝流道及燃料板换热物理过程的基础上，建立了描述矩形窄缝内单相流动与换热问题的数学模型，并给出了合理的边值条件；然后利用有限容积法对方程进行离散，根据SIMPLER算法的流程编制了模型求解程序；在验证程序正确性的基础上，对矩形窄缝流动与换热问题进行了求解，得到了矩形窄缝流道和板状燃料元件内部温度场、速度场的二维分布。

The law of heat transfer and pressure drop of two-phase of kerosene-air mixture at heating, boiling and condensation is obtained, the investigation result provides important basis for design of heat exchanger and heating furnace in hydrogenation technology of oil refining industry.

通过本文的研究，得到了煤油在含有不同量的空气时的煤油空气混合物两相流在加热、沸腾和冷凝时的换热和压降规律，建立了计算关联式，为炼油工业加氢工艺中的各种换热器和加热炉的设计提供了重要依据。

The kernel of the idea is that CPMJI that involves two-phase heat convection, jet impinging and full vaporization is used to enhance the heat transfer potential of cooling medium and obtain the best cooling effect.

该方法的核心是利用低温喷雾射流冲击的低温气液两相射流冲击和充分汽化的强化换热优势，充分发挥冷却介质的换热潜力以获得绿色高效的冷却效果。

It plays an important part in saving energy and decreasing the volume and weight of heat exchanger.

本文所研究的被称为强化传热革命的三维内肋管就是应用于各种换热器中单相强迫对流换热的新型强化传热管。

Single-phase forced convective heat transfer inside tube is an important research realm in the technology of heat transfer enhancement. It plays an important part in saving energy and decreasing the volume and weight of heat exchanger.

管内单相流体强制对流换热是强化传热技术的重要研究领域，其在降低换热器的能源消耗，减小换热器的体积和重量起着十分重要的作用。

We cannot compare a 1.4m wide machine with a 2.5m wide machine, or a machine with no splicers and no auto slitter scorer, with a machine that has automatic splicers, auto change, zero tail, gapless order change and so on.

我们不能将1.4m幅宽的设备同2.5m幅宽的设备相比较，同样也无法将不带接纸装置和自动纵切压痕装置的设备同具备自动接纸、自动换单、零纸尾、无缝换单等功能的设备相提并论。

The thesis mainly researches on the single phase AC/AC converter in the topologies including AC_Buck and AC_Cuk. Firstly, the operating principles of the two converters are analyzed in detail and the rules of their parameters design are educed; The commutation of their power switches which is the key of these topologies to realize is analyzed in detail and a feasible solution which can be named RCD-Commutation mode is presented and proved effectual by theory analyses and simulation results.

本文首先分析了AC_Buck变换器的变换原理，得出了电路参数设计准则；继而对电路实现的难点即功率管换流问题进行了深入分析，并得出了一种可行的解决方案即RCD换流方案；作为对简单拓扑单相直接AC/AC变换器控制策略的探索，本文以AC_Buck为平台，对电压单闭环瞬时值控制方案进行了研究，在理论分析和仿真研究的基础上设计并制作了一台采用RCD换流、电压单闭环瞬时值控制的AC_Buck变换器原理样机。

It has been put forward that there exists single Ball point and double Ball points on the symmetrical connecting-rod curves of equilateral mechanisms.

从鲍尔点的形成原理出发，分析对称连杆曲线上鲍尔点的产生条件，提出等边机构的对称连杆曲线上有单鲍尔点和双鲍尔点。

The factory affiliated to the Group primarily manufactures multiple-purpose pincers, baking kits, knives, scissors, kitchenware, gardening tools and beauty care kits as well as other hardware tools, the annual production value of which reaches US$ 30 million dollars.

集团所属工厂主要生产多用钳、烤具、刀具、剪刀、厨具、花园工具、美容套等五金产品，年生产总值3000万美元，产品价廉物美、选料上乘、质量保证，深受国内外客户的青睐