英文毕业论文细谈

第一篇：英文毕业论文细谈

一篇优质的毕业论文，它的目录也一定是很精简，一目了然的。因为普通的毕业论文都有一万字上下，篇幅很长，尽管设了分标题，但读起来也还是比较费力的。而在开篇设一个目录，便能让读者简洁明了的看懂你的文章框架结构以及大致走向。所以，今天优越论文网服务老师就来给大家讲解一下目录的制作。

一、清楚目录提纲之间的关联。

优越论文网老师提醒留学生，在之前已经比较了开题报告和提纲的区别，现在要知道目录和提纲的关系。

学生写了开题报告，对于文章的选题方向，当前国内外研究状态，自己要论证的观点有了介绍；在此基础上列出outline，文章要分为哪几大部分论述，每一部分内部又要用哪些分标题、内容来证明，可以写得比较简单、大概、笼统。而目录又是在提纲的基础上进一步准确无误地呈现全部文章的结构。

二、了解目录的重要性。

1、通过阅读目录，读者能够在阅读文章之前对全文的内容、结构有一个大致的了解，以此来决定对于此文是读还是不读，是要略读还是精读。你的文章有没有参考价值，能不能作为别人研究的二手资料。

2、目录可以为读者在选择论文中的某个分论点是提供极大的方便。比如在Word、PDF或是其他格式下阅读，读者认为某一部分可以适当引用的，只需要根据目录迅速定位即可。

3、目录作为论文的导读图，必定是准确的，与文章的纲目一致，即目录中的每一个分标题在文中都有对应关系。必定是清楚无误的，后面对应的页码也是正确的。必定是完整的，作者在制作目录的时候补课不可缺少某一标题，尤其是大的板块标题。

三:制作目录方法。

在Word中最简单也最麻烦的就是在大标题后的一页手录进去，然而对于文档的使用比较熟悉的人会发现，有着更为便捷准确的方法，英国优越论文网老师特别为留学生们总结如下内容。

1、在文档开头，选中要设置一级标题的文字内容，设置好字体、字号等格式，然后选择菜单中的“格式”-“段落”-“缩进和间距”选项卡-“大纲级别”设为1级!(关键步骤!)-“确定”。用同样的办法可以设置二级、三级....标题，区别就是在“大纲级别”里相应选择2级、3级等。

2、用刚设置好的一级标题去刷其它一级标题，其它级别标题依此类推。

3、光标放到想插入目录的位置点“插入”-“引用”-“索引和目录”-“格式”，右边的“显示级别”选择你前面设置过的最大目录级别，最后 “确定”。

目录能够帮助读者更方便的阅读你的论文，同学们一定要重视起来哦！以上就是优越论文网服务老师对论文目录的简单介绍了。优越论文网是一家英国留学申请与论文作业辅导的正规机构,在过去的10年时间里,帮助了英国高校学生顺利申请了一大批英国名校,以及辅导留学生们完成了coursework, assignment，essay, assignment, research proposal, presentation等各种文书的辅导,得到成千上万的留学生的真正认可.到2015为止，优越论文网实现了客服24小时在线一对一的客户沟通；我们拥有最专业的评估团队, 我们的turn-it-in系统检测帮助留学生朋友保证他们的论文原创性； 同时, 我们还有着庞大的英国院校师资力量支持等优势.如果还有什么不懂的欢迎随时打电话来咨询优越论文网服务老师哦！

第二篇：英文毕业论文陈述句

sci 句型大全作者： 满大鹏

再也不用愁SCI了，再也不愁论文中的英文怎么写了！！英语学术论文常用句型 来源： 辛亮的日志 英语学术论文常用句型 Beginning 1.In this paper, we focus on the need for 2.This paper proceeds as follow.3.The structure of the paper is as follows.4.In this paper, we shall first briefly introduce fuzzy sets and related concepts 5.To begin with we will provide a brief background on the Introduction 1.This will be followed by a description of the fuzzy nature of the problem and a detailed presentation of how the required membership functions are defined.2.Details on xx and xx are discussed in later sections.3.In the next section, after a statement of the basic problem, various situations involving possibility knowledge are investigated: first, an entirely possibility model is proposed;then the cases of a fuzzy service time with stochastic arrivals and non fuzzy service rule is studied;lastly, fuzzy service rule are considered.Review 1.This review is followed by an introduction.2.A brief summary of some of the relevant concepts in xxx and xxx is presented in Section 2.3.In the next section, a brief review of the....is given.4.In the next section, a short review of...is given with special regard to...5.Section 2 reviews relevant research related to xx.6.Section 1.1 briefly surveys the motivation for a methodology of action, while 1.2 looks at the difficulties posed by the complexity of systems and outlines the need for development of possibility methods.Body 1.Section 1 defines the notion of robustness, and argues for its importance.2.Section 1 devoted to the basic aspects of the FLC decision making logic.3.Section 2 gives the background of the problem which includes xxx 4.Section 2 discusses some problems with and approaches to, natural language understanding.5.Section 2 explains how flexibility which often...can be expressed in terms of fuzzy time window 6.Section 3 discusses the aspects of fuzzy set theory that are used in the...7.Section 3 describes the system itself in a general way, including the …..and also discusses how to evaluate system performance.8.Section 3 describes a new measure of xx.9.Section 3 demonstrates the use of fuzzy possibility theory in the analysis of xx.10.Section 3 is a fine description of fuzzy formulation of human decision.11.Section 3, is developed to the modeling and processing of fuzzy decision rules 12.The main idea of the FLC is described in Section 3 while Section 4 describes the xx strategies.13.Section 3 and 4 show experimental studies for verifying the proposed model.14.Section 4 discusses a previous fuzzy set based approach to cost variance investigation.15.Section 4 gives a specific example of xxx.16.Section 4 is the experimental study to make a fuzzy model of memory process.17.Section 4 contains a discussion of the implication of the results of Section 2 and 3.18.Section 4 applies this fuzzy measure to the analysis of xx and illustrate its use on experimental data.19.Section 5 presents the primary results of the paper: a fuzzy set model..20.Section 5 contains some conclusions plus some ideas for further work.21.Section 6 illustrates the model with an example.22.Various ways of justification and the reasons for their choice are discussed very briefly in Section 2.23.In Section 2 are presented the block diagram expression of a whole model of human DM system 24.In Section 2 we shall list a collection of basic assumptions which a...scheme must satisfy.25.In Section 2 of this paper, we present representation and uniqueness theorems for the fundamental measurement of fuzziness when the domain of discourse is order dense.26.In Section 3, we describe the preliminary results of an empirical study currently in progress to verify the measurement model and to construct membership functions.27.In Section 5 is analyzed the inference process through the two kinds of inference experiments...This Section 1.In this section, the characteristics and environment under which MRP is designed are described.2.We will provide in this section basic terminologies and notations which are necessary for the understanding of subsequent results.Next Section 2.The next section describes the mathematics that goes into the computer implementation of such fuzzy logic statements.3.However, it is cumbersome for this purpose and in practical applications the formulae were rearranged and simplified as discussed in the next section.4.The three components will be described in the next two section, and an example of xx analysis of a computer information system will then illustrate their use.5.We can interpret the results of Experiments I and II as in the following sections.6.The next section summarizes the method in a from that is useful for arguments based on xx Summary 1.This paper concludes with a discussion of future research consideration in section 5.2.Section 5 summarizes the results of this investigation.3.Section 5 gives the conclusions and future directions of research.4.Section 7 provides a summary and a discussion of some extensions of the paper.5.Finally, conclusions and future work are summarized 6.The basic questions posed above are then discussed and conclusions are drawn.7.Section 7 is the conclusion of the paper.Chapter 0.Abstract 1.A basic problem in the design of xx is presented by the choice of a xx rate for the measurement of experimental variables.2.This paper examines a new measure of xx in xx based on fuzzy mathematics which overcomes the difficulties found in other xx measures.3.This paper describes a system for the analysis of the xx.4.The method involves the construction of xx from fuzzy relations.5.The procedure is useful in analyzing how groups reach a decision.6.The technique used is to employ a newly developed and versatile xx algorithm.7.The usefulness of xx is also considered.8.A brief methodology used in xx is discussed.9.The analysis is useful in xx and xx problem.10.A model is developed for a xx analysis using fuzzy matrices.11.Algorithms to combine these estimates and produce a xx are presented and justified.12.The use of the method is discussed and an example is given.13.Results of an experimental applications of this xx analysis procedure are given to illustrate the proposed technique.14.This paper analyses problems in 15.This paper outlines the functions carried out by...16.This paper includes an illustration of the...17.This paper provides an overview and information useful for approaching 18.Emphasis is placed on the construction of a criterion function by which the xx in achieving a hierarchical system of objectives are evaluated.19.The main emphasis is placed on the problem of xx 20.Our proposed model is verified through experimental study.21.The experimental results reveal interesting examples of fuzzy phases of: xx, xx 22.The compatibility of a project in terms of cost, and xx are likewise represented by linguistic variables.23.A didactic example is included to illustrate the computational procedure Chapter 1.Introduction Time 1.Over the course of the past 30 years,..has emerged form intuitive 2.Technological revolutions have recently hit the industrial world 3.The advent of...systems for has had a significant impact on the 4.The development of...is explored 5.During the past decade, the theory of fuzzy sets has developed in a variety of directions 6.The concept of xx was investigated quite intensively in recent years 7.There has been a turning point in...methodology in accordance with the advent of...8.A major concern in...today is to continue to improve...9.A xx is a latecomer in the part representation arena.10.At the time of this writing, there is still no standard way of xx 11.Although a lot of effort is being spent on improving these weaknesses, the efficient and effective method has yet to be developed.12.The pioneer work can be traced to xx [1965].13.To date, none of the methods developed is perfect and all are far from ready to be used in commercial systems.Objective / Goal / Purpose 1.The purpose of the inference engine can be outlined as follows: 2.The ultimate goal of the xx system is to allow the non experts to utilize the existing knowledge in the area of manual handling of loads, and to provide intelligent, computer aided instruction for xxx.3.The paper concerns the development of a xx 4.The scope of this research lies in 5.The main theme of the paper is the application of rule based decision making.6.These objectives are to be met with such thoroughness and confidence as to permit...7.The objectives of the...operations study are as follows: 8.The primary purpose/consideration/objective of 9.The ultimate goal of this concept is to provide 10.The main objective of such a...system is to 11.The aim of this paper is to provide methods to construct such probability distribution.12.In order to achieve these objectives, an xx must meet the following requirements: 13.In order to take advantage of their similarity 14.more research is still required before final goal of...can be completed 15.In this trial, the objective is to generate...16.for the sake of concentrating on...research issues 17.A major goal of this report is to extend the utilization of a recently developed procedure for the xx.18.For an illustrative purpose, four well known OR problems are studied in presence of fuzzy data: xx.19.A major thrust of the paper is to discuss approaches and strategies for structuring..methods 20.This illustration points out the need to specify 21.The ultimate goal is both descriptive and prescriptive.22.Chapter 2.Literature Review 23.A wealth of information is to be found in the statistics literature, for example, regarding xx 24.A considerable amount of research has been done..during the last decade 25.A great number of studies report on the treatment of uncertainties associated with xx.26.There is considerable amount of literature on planning 27.However, these studies do not provide much attention to uncertainty in xx.28.Since then, the subject has been extensively explored and it is still under investigation as well in methodological aspects as in concrete applications.29.Many research studies have been carried out on this topic.30.Problem of xx draws recently more and more attention of system analysis.31.Attempts to resolve this dilemma have resulted in the development of 32.Many complex processes unfortunately, do not yield to this design procedure and have, therefore, not yet been automated.33.Most of the methods developed so far are deterministic and /or probabilistic in nature.34.The central issue in all these studies is to 35.The problem of xx has been studied by other investigators, however, these studies have been based upon classical statistical approaches.36.Applied...techniques to 37.Characterized the...system as 38.Developed an algorithm to 39.Developed a system called...which 40.Uses an iterative algorithm to deduce 41.Emphasized the need to 42.Identifies six key issues surrounding high technology 43.A comprehensive study of the...has been undertaken 44.Much work has been reported recently in these filed 45.Proposed/Presented/State that/Described/Illustrated/ Indicated/Has shown / showed/Address/Highlights 46.Point out that the problem of 47.A study on...was done / developed by [] 48.Previous work, such as [] and [], deal only with 49.The approach taken by [] is 50.The system developed by [] consists 51.A paper relevant to this research was published by [] 52.[]'s model requires consideration of...53.[]' model draws attention to evolution in human development 54.[]'s model focuses on...55.Little research has been conducted in applying...to 56.The published information that is relevant to this research...57.This study further shows that 58.Their work is based on the principle of 59.More history of...can be found in xx et al.[1979].60.Studies have been completed to established 61.The...studies indicated that 62.Though application of xx in the filed of xx has proliferated in recent years, effort in analyzing xx, especially xx, is lacking.Problem / Issue / Question 63.Unfortunately, real-world engineering problems such as manufacturing planning do not fit well with this narrowly defined model.They tend to span broad activities and require consideration of multiple aspects.64.Remedy / solve / alleviate these problems 67....is a difficult problem, yet to be adequately resolved 68.Two major problems have yet to be addressed 69.An unanswered question 70.This problem in essence involves using x to obtain a solution.71.An additional research issue to be tackled is....72.Some important issues in developing a...system are discussed 73.The three prime issues can be summarized: 74.The situation leads to the problem of how to determine the...75.There have been many attempts to 76.It is expected to be serious barrier to 77.It offers a simple solution in a limited domain for a complex

第三篇：毕业论文英文致谢

毕业论文致谢1 First of all, I would like to thank my mentor professor Xiang Ji During my pH.d., teacher Ji teach by precept and example，and let me learn a lot such as how to be a good man and learn the truth.In my doctoral thesis research in the face of a huge field, teacher Ji in the topic direction, the paper structure, thesis methods and other aspects are tirelessly inspired and guided by me, step by step in order to guide my progress.The years of my Ph.D.is the most memorable time in my life。Teacher Ji rigorous academic attitude and a strong spirit of innovation always infected me, urging me, encourage me, and it will benefit me all my life, along with me on the academic road of the future.Secondly，thank to Professor Jian Xia，School of architecture and urban planning of Suzhou University of science and technology, Xia teacher from the research materials and research methods, and many other aspects of my paper to provide a great help, So that my paper is possible to complete.I would like to thank Prof.Liu Zuyi of Suzhou University of Science and Technology for their excellent guidance and review of my paper.I benefited a lot.I would like to thank Professor Jiang Chang of the School of Mechanics and Civil Engineering, China University of Mining and Technology, for giving me a great idea of my thesis.Their suggestions in the field of underground space are very enlightening for the paper.Their help made the paper go smoothly.Thanks to the Tsinghua University School of architecture professor Weimin Zhuang and Beijing University of Technology School of architecture and urban planning of professor Jian Dai on my thesis detailed review.Thanks to the China University of Mining and Technology School of mechanics and civil engineering professor Junwu Xia on my thesis guidance and comments.I would like to thank the senior engineer of Chen Jun, Jiangsu Provincial Planning and Design Institute, for his important help during my research.I would like to thank Professor Lian Si of Suzhou University of Science and Technology for their valuable suggestions.Thanks to Professor Yingxin Zhu of the School of Architecture for my patience.I would like to thank the chief architect of Rongguo Hu of China Academy of Building Research for my important suggestion.Thanks Hui Wang Associate Professor, Jie Hong associate professor, teacher Chao Luo, teacher Chaochao Chu and Rui Ma, Jun Lan, Hao Wang, Jian Tong Zhao, Da Zhang, Dong Wang, Xinbin Liang, Jiaqi Zhu and other teachers, The discussion of the paper and the warm help.Thanks Huiyu Sun for helping me.Thanks Yang Yang for helping me.Thanks Yunmin Jiang for helping me.Finally I would like to thank my parents for many years of my training, and in my study and research with great encouragement and life of my spirit on the full support.致谢2

Thanks to my tutor Professor ChenFei , this paper was completed under the guidance of the tutor.Without the guidance, encouragement and financial support , the paper can not be successfully completed.I have fruitful results and deep feelings in the five years of successive postgraduate and doctoral programs of study.Tutor's excellent quality of behavior, rigorous attitude, the spirit of innovation, ability to grasp the overall situation and sweep down irresistibly from a commanding height, selfless work spirit for students to establish a model of a subtle role, this is also the most valuable wealth that tutors impart to students.In this regard, I would like to pay deep tribute to my tutor.Thanks to Professor Tian Zuzhi, he has been taking the utmost care it from selection of subject to completion of this thesis.Even in his busy schedule, Professor Tian also took time to read the article, and put forward many valuable comments and suggestions, so that the author benefited greatly.I would like to take this opportunity to express my deep gratitude and respect to Professor Tian Zuzhi.Grateful to professor Li Aimin, associate professor Meng Deyuan, associate professor Liu Shanzeng, postdoctoral Qiu Bingjing for the guidance and help in the theoretical analysis and experimental research of the paper.Express heartfelt gratitude to the leadership and staff of Xuzhou five Ocean Science and Technology Ltd, which received great support in the design, manufacture and assembly process of the experimental platform , especially the Mr Deng Zhipeng, Mr Meng Zhigang , Mr Wu Hongzhi, Engineer Yue Fuliang and other workshop Masters.Thank you for the help and care given by the teachers, brothers and sisters in the laboratory and life.Thank you for the happy time they spent with me for five years.Thanks to my family for their care, understanding and support,their selfless dedication and silent hard work is the driving force and courage for me to move forward.In the coming days, I will repay them with all my heart with gratitude.I would like to offer my highest respect and sincere thanks to my family.Thank you for the relevant expert and scholar to review my thesis in their busy schedule, and put forward valuable guidance and suggestions.In this regard, I would like to express my deep gratitude to all the experts and scholars.致谢3 I would never have been able to successfully finish this Ph.D thesis without the guidance of my supervisor, and help from my friends as well as support from my family.First of all, I would like to express my deepest gratitude to Prof.Cao Yijun for his extensive guidance on my research work: from the topic of the thesis, experiments, to the writing of this thesis.His immense knowledge, rigorous attitude and tireless teaching greatly benefited me.I would like to thank him for the advice he provided on both research as well as life in general.Besides my supervisor, I would like to thank Liu Shaofang, professor of Public Foreign Languages at CMUT, who taught me how to write professional thesis in English and laid a good foundation for my doctoral degree.In addition, I am grateful to all teachers from School of Chemistry and Engineering at CUMT, for their help on scientific research methods.Last but not least, a special thanks to my family for supporting me spiritually throughout writing this thesis and my life.I would not be in the position where I am now without their love, encouragement and understanding.

第四篇：超声相控阵技术细谈

航空无损检测新技术之

超声相控阵技术的发展及应用

学院：测试与光电工程学院 班级：080812班 姓名：郭林

超声相控阵技术的发展及应用

郭林

(南昌航空大学 测试与光电工程学院0808012班)

摘要: 扼要介绍超声相控阵技术的发展历史、原理及特点。着重介绍其最新研究动态及其在无损检测与评价中的典型应用。指出将相控阵技术同其它诸如纵波一发一收(TRL)、声时衍射(TOFD)技术、数字信号处理(DSP)及成像等技术结合起来,将有助于充分发挥其特点,提高其检测能力,促进无损检测与评价的发展及应用。

关键词: 超声检验;相控阵技术;换能器;

Abstract : The development history , theory and characterization of ultrasonic phased array technique , especially the state2of2the2arts and applications of the technique in nuclear industry nondestructive testing and evaluation(NDT & E)are described.Combining phased array technique with TRL(the transmitter2receiver technique for longitudinal waves), TOFD(time of flightdiffraction), DSP(digital signal processing)and imaging technique will improve detectabilityand promote NDT&E developmentand application.Keywords :Ultrasonic testing;Phased array technique;Transducer;

前 沿： 超声检测是根据超声波在材料中传播特性，检测材料中的缺陷。向工件中发射超声波；超声波在工件中传播，遇到缺陷，传播特性改变，检测变化后的超声波，并进行处理和分析；根据接收波的特征，评估工件内存在缺陷的特性。在超声无损检测新技术中，大概有相控阵检测技术、电磁超声检测技术、激光超声检测技术、声振检测技术等。其中超声相控阵技术已有近20 多年的发展历史。初期主要应用于医疗领域,医学超声成像中用相控阵换能器快速移动声束对被检器官成像利用其可控聚焦特性局部升温热疗治癌,使目标组织升温并减少非目标组织的功率吸收。最初,系统的复杂性、固体中波动传播的复杂性及成本费用高等原因使其在工业无损检测中的应用受限。然而随着电子技术和计算机技术的快速发展,超声相控阵技术逐渐应用于工业无损检测,特别是在核工业及航空工业等领域。如核电站主泵隔热板的检测;核废料罐电子束环焊缝的全自动检测及薄铝板摩擦焊焊缝热疲劳裂纹的检测。

近几年,超声相控阵技术发展尤为迅速,在第 15 届世界无损检测会议中,关于超声相控阵技术的文献有 17 篇之多。在相控阵系统设计、系统仿真、生产与测试和应用等方面已取得一系列进展,如采用新的复合材料压电换能器改善电声性能;奥氏体焊缝、混凝土和复合材料等的超声相控阵检测;R/ D TECH ,SIEMENS 及 IMA2SONIC 等公司已生产超声相控阵检测系统及相控阵换能器。而动态聚焦相控阵系统[10 ],二维阵列、自适应聚焦相控阵系统,表面波及板波相控阵换能器和基于相控阵的数字成像系统等的研制、开发、应用及完善已成为研究重点。其中,自适应聚焦相控阵技术尤为突出,它利用接收到的缺陷回波信息调整下一次激发规则,实现声束的优化控制,提高缺陷(如厚大钛锭中的小缺陷或埋藏较深的大缺陷)的检出率。目前,国内在超声相控阵技术上的研究应用尚处于起步阶段,主要集中于医疗领域。

1原理及特点

超声相控阵就是采用一个探头多个晶片的有机排列，利用计算机技术不同时间对每个晶片发出激励信号 和接收声波，使合成的超声波形受计算机的控制，产生不同的方向，聚焦点等等。从而完成检测。我们知道普通的超声聚焦探头可以将超声波聚焦在某一点处，从而可以在该点处获得最好的分辨率和灵敏度，但对不处于该位置的缺陷就没有这么好的分辨率和灵敏度了。而相控阵探头的聚集位置是可以由计算机控制的，是动态可变化的，所以可在声程范围内设定聚集的范围，计算机可自动控制探头各个晶片发射和接收超声波，从而在该范围内进行动态聚集，所以聚集是一条线。如下图。

这样扩展了聚集范围，其优点可以从下面的例子看出，这是一块试块，有三个人工孔，最近的离表面距 离为 25mm,试块高 75mm。如采用聚集在 25 mm 处时，如图可见孔的图像清楚，但底面回波图像模糊。如采用聚集在 75 mm 处时，如图可见孔的图像模糊，但底面回波图像清楚。如采用动态聚集，聚集在 25 mm —75 mm 处时，如图可见孔的图像和底面回波图像都很清楚。这意味着发射超声可以由电子控制扫查聚集，同时接收超声也由电子控制扫查聚集，从而完成整个设定深度范围内的聚集。这就是动态聚集的优点。前面提到超声相控阵可以由计算机控制不同晶片发射和接受超声波的时间点，从而可以合成不同的发射波的角度，我们可以在仪器中设定超声波扫查的角度范围，计算机就驱动扫查晶片的合适方式，使超声波在某一角度范围内进行扫查检测，如下图图示。

在每个重复脉冲周期里，在晶片电子扫查过程中同时被激发和接收的组，按预定程序

移动。无需光珊移动，就能全面覆盖被检区域。如图所示

如此时探头沿着与晶片排列垂直的方向移动，并由一编码器配合记录行程，这就可以完成超声相控阵 C扫描检测，与传统的 C 扫描相比，效率高得多，在波音 787 飞机中，由于没有铆钉连接蒙皮，在检测中难以判断是缺陷还是复合材料机身内的结构的影响。可以在机身外采用该方法以查明内部结构，快速高效。在目前的飞机上应用该方法，可以查找蒙皮搭接处的内部腐蚀，如下图所示：

超声相控阵换能器的设计基于惠更斯原理。换能器由多个相互独立的压电晶片组成阵列,每个晶片称为一个单元,按一定的规则和时序用电子系统控制激发各个单元,使阵列中各单元发射的超声波叠加形成一个新的波阵面。同样,在反射波的接收过程中,按一定规则和时序控制接收单元的接收并进行信号合成,再将合成结果以适当形式显示。由其原理可知,相控阵换能器最显著的特点是可以灵活、便捷而有效地控制声束形状和声压分布。其声束角度、焦柱位置、焦点尺寸及位置在一定范围内连续、动态可调;而且探头内可快速平移声束。因此,与传统超声检测技术相比,相控阵技术的优势是：

①单轴扇形扫查替代栅格形扫查可提高检测速度。

②不移动探头或尽量少移动探头可扫查厚大工件和形状复杂工件的各个区域,成为解决可达性差和空间限制问题的有效手段。

③通常不需要复杂的扫查装置,不需更换探头就可实现整个体积或所关心区域的多角度多方向扫查,因此在核工业设备检测中可减少受辐照时间。④优化控制焦柱长度、焦点尺寸和声束方向,在分辨力、信噪比、缺陷检出率等方面具有一定的优越性。

超声相控阵还不是十分完美，还有需要进一步改进的方面 ： 1． 探头体积还太大，特别在航空器上好多地方难以运用 2． 探头导线非常精密。容易损坏 3． 仪器参数设置非常复杂 4． 相应的标准规范还没有跟上

相控阵技术在实现上要面临诸多挑战,如要求压电晶片电声性能好;相邻单元间隔声性能好;避免产生旁瓣,声束角度较大时更应注意该问题;时间延迟的精确控制以及声束方向、形状及声压分布的仿真等。超声相控阵换能器按其晶片形式主要分三类,即线阵、面阵和环形阵列。线阵最为成熟,已有含256 个单元的线阵(N ×1), 可满足多数情况下的应用要求;面阵又叫二维阵列(N ×M),可对声束实现三维控制,对超声成像及提高图像质量大有益处,目前已有含 128 ×128 阵列的超声成像系统应用于金属和复合材料的检测与性能评价[14 ] ,该系统具有实时 C 扫描成像功能,以标准视频图像在液晶显示器上显示,然而同线阵相比,面阵的复杂性剧增,其经济适用性影响该类探头在工业检测领域的应用;环形阵列在中心轴线上的聚焦能力优异、旁瓣低、电子系统简单、应用广泛,但不能进行声束偏转控制。

典型应用

在核动力装置及设备中,厚壁工件、粗晶材料和复杂形状工件多,设备和管道中某些焊缝可达性及可检性差而申请免检多。此时,应用相控阵技术可提高检测效率,减少辐照时间,扩大超声检测应用范围,取得显著的经济效益和社会效益。用相控阵技术对盛装核废料的罐体封头和筒体间电子束焊环焊缝进行100 %全自动超声检测,可避免采用复杂机械装置,利用其动态聚焦能力并结合分离谱技术可减少粗晶的影响,提高信噪比。采用含 64 个单元的相控阵换能器进行水浸法 B 扫描检测,在模拟试块中可检出焊缝区内直径为13mm 的人工边孔。

900MW 压水堆主泵隔热板热疲劳裂纹的检测存在的困难是,凸缘和轴承之间空间狭小(图2),探头移动空间极为有限,可达性差;双曲面形状的凸缘使声束强烈发散。然而,使用具有 16 个单元的线性阵列探头进行检测,可不拆卸轴承和密封圈等结构;具有双曲面形状的楔块可实现探头和凸缘间的耦合;根据楔块形状调整延迟,校正畸变声场。该系统可扫查圆周外表面以下 200mm 的范围,可检出径向平面内 5mm 以上的疲劳裂纹粗晶奥氏体钢在核工业中应用广泛,但其可靠检测一直是个难题。最新研究表明,相控阵技术同TRL 及 DSP 技术结合起来已成为行之有效的检测手段,其最大特点是检测信噪比高,且只需一个相控阵换能器就可检测不同深度缺陷。汽轮机转子叶根、轮槽和键槽等的超声检测由于其结构限制而难以用普通单一探头进行。以叶根检测为例,若使用相控阵换能器,可在不拆卸叶片的条件下从三个方向检测,既能提高检测效率,又能避免拆卸损坏。在其它工业领域,相控阵技术亦有着广泛的应用,如压力容器、高能管道焊缝和输油管道焊缝的检测。R/ D TECH 公司研制的管道全自动超声相控阵系统可检测壁厚 650mm ,直径 100 1 400mm的管道,扫查速度为100mm/ s ,4min 可检测一条完整的陆地输油管焊缝(包括仪器安装和拆除),结合声时衍射技术(TOFD)提高缺陷检出能力和定量精度。

3结论

超声相控阵技术的特点及在众多富有挑战性检测中的成功应用,使之成为超声检测的重要方法之一。由于它可以灵活而有效地控制声束使之具有广阔的应用与发展前景,将其同信号分析与处理、数字成像和声时衍射等技术结合起来是其主要发展方向。显然,超声相控阵技术的应用将有助于改善检测的可达性和适用性,提高检测的精确性、重现性及检测结果的可靠性,增强检测的实时性和直观性,促进无损检测与评价的应用及发展。

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美国无损检测学会编《, 美国无损检测手册》译审委员会译.美国无损检测手册·超声卷(上册)

第五篇：毕业论文 英文文献翻译

_______ 学 院

毕业论文文献资料翻译

原文名称: “Goldilocks” Liberalization: The Uneven Path Toward Interest Rate Reform in China

课题名称:利率市场化对我国商业银行的影响分析

学生姓名:号:

指导老师:

所在系部:专业名称:

年月

译文

“金发”自由化：中国利率市场化改革的不平之路

Shih and Victor

中国政府的自由化

2003年，中国从亚洲金融危机进入到一段时间的持续增长后，利率市场化改革似乎终于在掌握之内。就如以前一样，中国人民银行的热衷者发布几篇报告以支持利率市场化，而四大银行的代表也提供放慢改革（成2002年）的理由。此外,中国在2003终于摆脱通货紧缩的威胁并恢复相对高速的增长，只有在2004年有中等程度的通胀（图3）。一些惊喜，在2004年10月29日，对贷款利率的上限被解除，允许银行以他们想要的高利息收费（人民日报2005）。此外，银行也可以给予储户低于存款基准利率的利率。类似总督戴显龙的几年前的时间表，中国人民银行发布了一份报告，奠定了完全利率市场化的具体计划。

尽管推行这种市场化，但金融体系的基本逻辑任然保持了一样。在存款方面，存款利率上下限的去除主要是象征性的，因为银行没有理由去不必要地降低利率，使其低于他们的竞争对手所提供的利率。因此，很少数的银行利用市场化的优势来给出低于存款基准利率的利率（2006年绿色）。关于贷款利率市场化，央行的理由是，它将使银行“根据客户不同风险的状况给予不同的贷款和利率”（2005年中国人民银行货币政策研究小组）。虽然这听起来像一个显著的效率增益，但这是发出了现实的信号，即银行继续提供廉价融资，给予有更低的官僚风险状况的国家资助项目和国有企业。在此期间，通过存款利率上限和贷款利率的下限，银行之间的“毁灭性竞争”仍然受到严格的限制。因此，银行仍然不能通过提供更高的存款利率互相竞争。同样，银行无法通过提供给借款者更低的利率来相互竞争，因为银行能提供的最低利率为基准利率的90％。中国人民银行的一份报告显示，整个国有银行全部贷款的27％，被设臵于法定最低利率，这表明银行将会通过给出法定最低利率来竞争（中国人民银行货币政策的研究团队 2005）。为了给中国人民银行信贷，促使城市商业银行和农村信用社贷款利率的市场化，通过提供更多高利率的贷款给在私营部门的高风险的的借款人，提供融资给原先被冻结的正规银行系统分部（中国人民银行货币政策的研究团队 2005）。

进入2008-2009年的经济衰退，对利率的再次控制促进了大规模的反周期投资驱动器。如图2所示，中国人民银行在全球经济低迷时继续保证银行业稳健的利率传导。移

除贷款利率的上限，银行通过贷款赚更多的钱。因此，当中央要求银行于2008年11月为4万亿人民币经济刺激方案提供融资，银行以极大的热情回应。导致2009年中国的贷款向上急速膨胀，比上年增长了惊人的30％。中国人民银行在2009年原本设臵信贷配额是5万亿人民币向上一点点。到今年年底，银行已经做出了历史上最大量的新增贷款，总额近10万亿人民币（潘克赫斯特,郑,和王 2009）。银行持有的存款利率低于基准利率而贷款利率高于基准利率，实际上可收获可观的利润，即使在经济衰退期间（汉2009）。因此，贷款利率上界的自由化得益于所有有关的政治人物。高层的技术专家保留为最大的反周期投资驱动凑集资金的能力，这在中国的历史上是相对容易的。银行仍然防止“毁灭性竞争”，并继续享有稳健的贷款利率传导。由于银行为经济刺激计划提供资金的意愿，财政部不需要发行很多的债务，从而限制财政赤字的规模。虽然一些大型国有企业由于释放出的贷款利率可能付出更高的借贷成本，银行急于提供大量的融资额给他们，使他们向其他实体转贷资金而赚取利润。随着世界逐步摆脱经济危机，由于前两年的快速信贷扩张，通货膨胀的压力在中国建立的非常迅速。2011年初，通货膨胀调转进入危险的境况。然而中国领导人在危机模式下，利率进一步自由化的任何谈话被搁臵。另一位金发的时刻必须在下一轮利率自由化之前提出，使其可以被理解。

结论

虽然中国并没有回应外部强加给我们的政策改革压力，但是它已经开始自身的重大经济改革。在城市里，许多规模较小的国有企业被私有化或关闭了，而私营部门被允许自由成长（诺顿1996）。大多数商品和服务价格已经被放开（韦德曼2003）。尽管中国经济发生了翻天覆地的变化，但是国家将继续以控制社会的宏观的经济杠杆，允许它通过重要的途径影响经济效果。中央级的技术专家可以通过控制资金的流动和投资方向，确保通胀不上升至无法控制的地步，而增长依然强劲。同时，这些手段也允许他们购买被其他政治局成员保护的利益支持，包括当地官员和国有企业管理人员，特别是在经济停滞的时候。为了保持这些手段的有效性，他们需要储户在中国的国家金融体系的抵押品。如果私人银行出现为存款人提供更高的利率，国有银行必须匹配上更高的利率，从而增加了成本，为大规模的经济刺激计划提供资金。尽管强大的激励促使顶级技术专家保持现状，但是利率市场化改革在中国已经取得了一些进展。即使在20世纪80年代，非正式的银行也提供着很高的存款利率。进入20世纪90年代，央行行长感受到西方关于货币政策以及中国人民银行政治性角色的担忧，开始认真的推行利率市场化。他们在通货膨胀低，经济增长强劲的时候推进自由化改革。

虽然方便政策制定者制定政治目标，但是中国的利率管制将继续使中国的储户以及一些国外的制造商肩负重但。只要银行争夺存款被禁止，数以百万的储户将继续被人为压低存款利率，来补贴国有银行的盈利能力。国家以较低的成本调动大量资金的能力，也有对世界的负面影响。大部分剩余的国有企业主要集中在重工业和大宗商品部门。因此，就如中国政府智囊团指出的那样，通过宽松的信贷政策，使他们得以保留，而在全球经济衰退的时候，或者在某些情况下，他们甚至扩大自己的能力（国际金融研究中心2009年）。这加剧了全球的产能过剩，并导致中国某些行业的商品，特别是钢材，在世界市场上引起倾销。因此，政府的持续努力以操纵利率，这种行为的一个重要受害者是中国国有企业的全球竞争者。