工作体积

The strain field normal to the boundary plane and the excess grain boundary volume are calculated and compared with the results obtained using the embedded-atom method .

在这项工作中，我们计算了垂直于晶界平面的法向应变场和晶界的过剩体积，并且与嵌入原子法所得到结果相比较，得到基本一致的结果。

In the process of building and using the mass concrete structures, because of the effect of out-side condition and themselves, some faults will form in the structure, these faults will effect the bearing capability and endurance Using nondestructive testing method to test the concrete"s quality and diagnose its healthy, which has the significant sense in assessing the safety stability and research of the administering diseasesThis dissertation mostly researched the testing methods in the mass concrete structure, discussed the principles, methods, features, sphere of application of the ultrasonic testing in the mass concrete structure with faults, used dynamic FEM to simulate the testing process, discussed when the concrete structure with cracks is under the effect of the pulse, how the elastic waves propagate and what are their changing feature, Researched the principles of the first-arriving waves" phase when the cracks" depths are not same, obtained the relation between the inversion point and the cracks" depth, which has the direction sense in the application of projects,The second part of this dissertation is CT , which used the ultrasonic wave running through the tested-substance to get arriving-time of the ultrasonic wave, then inverse the image This dissertation drawed one CT program which can well present the different little cells ultrasonic wave velocity profiles of the substance, thereby to diagnose the quality of the part of the tested-substance, CT has the better using foreground..

在混凝土结构的施工及使用过程中，由于受其自身及外界各种因素的影响，常常会产生一些缺陷，对结构物的承载能力和耐久性造成严重影响，采用无损检测技术进行质量检测和健康诊断，这对混凝土结构开展安全、稳定性评估以及病害隐患治理研究具有重要意义。本论文主要针对大体积混凝土结构缺陷的检测方法展开研究工作，重点讨论了超声波法检测混凝土结构裂缝的基本原理和方法及其特点、适用范围，运用动力有限元数值模拟其检测过程，探讨了有裂缝缺陷的混凝土结构在脉冲荷载作用下弹性波的传播及其变化特征，研究了不同裂缝深度下首波相位变化规律，得出了反转临界点与裂缝深度之间的关系，这对实际工程应用具有指导意义。声波CT是一种新的无损检测技术，它是利用声波穿透被检测体获取声波接收时间，来进行计算机反演成像的技术。本文利用直射线法编制了层析成像程序，能较好地呈现被检测物体各微小单元的声波速度分布图像，从而对检测体的质量状况作出诊断评估，具有较好的应用发展前景。

The results show that this attenuator, which is 12mm×8mm×0.5mm and works at low temperature, can be used alone or integrated into HTS system to decrease system volume and weight. Insertion loss of this attenuator is about 0.2dB, whose magnitude is one order lower than that of a conventional attenuator. Attenuation step about 0.01dB can be achieved, which is 1~2 orders lower in magnitude than conventional attenuators.

主要结论如下：光控高温超导微波可变衰减器在液氮温区工作，电路尺寸为12mm×8mm×0.5mm，可单独使用也可集成于高温超导系统中，可大幅减小系统的体积与质量；高温超导衰减器的插损小于0.2dB，比常规衰减器低1个量级；高温超导衰减器的可变衰减步进值小于0.01dB，比常规衰减器低1~2个量级。

This paper attempts to associate PFC technology with Quasi-Resonant DC/DC Converter and Synchronous Rectifier technology, to work out a novel switching power supply with higher efficiency and low contamination, which both achieved high power factor, improved effecting on electrical network and ensured high efficiency, furthermore, it is easy to be realized and controlled in circuit.

本文首先阐述了开关电源、功率因数校正技术和同步整流技术的发展及现状，对DC/DC变换的拓扑结构进行了选择，确定了带有隔离的准谐振(Quasi-Resonant)反激型电路，可以有效地降低损耗；接着本文对几种常见的PFC拓扑电路进行分析对比，从中选择了BOOST型电路，对工作在临界状况下的电路进行了分析，采用跟随输入电压的升压变换新技术，减小了电感体积，同时降低了开关管的电压应力，既简单又有效地实现了功率因数校正，并发现此技术值得推广；由于反激型变换器的效率一般都较低，所以本文在传统同步整流技术基础上对其加以改进，设计出一种新颖、高效的同步整流方案。

A new Arnage will appear this fall, but work has also begun on the next generation of Bentley's volume family, the Continentals.

一种新的宾利雅致将出现今年秋季，但工作也已经开始了下一代Bentley的体积家庭， Continentals 。

And our work is to synthesize the expandable graphite which has greater volume and lower sulfur content, with organic regent substituting for oil of vitriol and with some oxidants using to meet the need of the industry manufacture, to study the catalysis capability of the product.

我们的工作是改用有机介质逐步替换浓硫酸，在某些氧化剂的作用下制备出大膨胀体积，低硫含量的可膨胀石墨产品，使其符合工业生产需要，并对其催化性能进行初步研究。

In the United States, chronic alcoholism and hepatitis C are the most common ones.

在美国，慢性酒精中毒，肝炎是最常见的。

If you have any questions, you can contact me anytime.

如果有任何问题，你可以随时联系我。