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In this thesis,based on the DFT+NEGF first-principles method,we construct a lead-molecule-lead sandwich system with single benzene-based molecule to investigate the relationship between the structure and properties of the molecular devices and the factors that influence properties of the molecular devices.Our computational investigations on these molecular devices are primarily concentrated on the effect of contact geometry between molecules and electrodes,the effect of side groups,the effect of different torsion angle between two phenyl rings and the effect of external electric field.This thesis consists of five chapters:In Chapter one,we mainly introduce the research background and development of the molecular electronics,including the experimental fabrication of molecular electronic components and theoretical simulation methods.Afterwards we discuss the questions that need to be solved in this area.Finally,the main contents of this thesis are listed.In Chapter two,we introduce the theoretical methods used in this thesis, including the main first-principles calculation methods,i.e.,the Density-Functionmethod and nonequilibrium Green\'s function.

本论文拟采用密度泛函理论和非平衡格林函数相结合的第一性原理计算方法，选取苯基小分子作为研究对象，构建了金属电极/有机小分子/金属电极三明治结构体系，系统地研究了苯基分子器件结构的改变与分子电输运性质之间的关系以及影响分子器件电输运性质的相关因素，其中重点研究了分子与电极间可能的接触结构改变、官能团、分子间的扭转角以及外电场对苯基分子电输运性质的影响，本论文主要包括以下五个章节的内容：第一章为综述部分，主要介绍了分子电子学产生的背景、分子器件的研究意义、当前研究分子器件的实验和主要理论方法，以及目前在研究分子器件中存在的一些问题，最后给出了本论文的主要研究内容和技术路线。

First we depicted one theoretical model of LCoS device, and then working modes of LCoS used as phase-only SLM were selected and optimized by varied the twist angle of liquid crystals and polarized angle due to parameter space method, two working modes, which are suitable to apply LCoS as phase-only SLM, were found, that is (0°, 0°) and (0°, 52°). Theoretical study also showed that the (0°,52°) could be used as a compound device, it behaved property of intensity modulation if a working point was selected appropriately and it behaved property of phase modulation when another wording point was selected. At the same time, this two working modes were studied detailed by extended Jones matrix method.

首先建立了LCoS器件的理论模型，并采用参数空间的方法通过改变液晶的扭曲角度和偏振片的起偏角度选择和优化了LCoS器件用作相位调制的合适的工作模式，找到了两种比较合适的作为相位调制的工作模式----(0°，0°)和(0°，52°)配置。

It innovates not only the contents of theoretical animadversion but also the internal foundation of theoretical system, and thus it is more profound and revolutionary.

这种指向理论的逻辑前提和逻辑基础的反思，属于对构成理论的依据和原则的反思，它不仅改变了理论批判的内容，而且变革了理论之所以为理论的内在根据，这种反思更具深刻性、革命性。

New methods are put forward based on the theoretical basis and the anticipative experimental results, and are beneficial to the theoretical research and engineering applications in image fusion technology.

本文所提出的一些新方法具有理论基础和预期的实验结果，这些工作对图像融合技术的理论研究和工程应用具有一定的作用。

With the advancement of science and technology, some new theories and new ways emerged gradually, some of them merged with specific theoretical tools, this specific theoretical tools include mathematical morphology, fuzzy techniques, neural networks, wavelet and so on. Secondly, in this paper, it described and analyzed the segmentation method based on the edge in the domain of image segmentation in detail. It did experiments on several edge detection operators using MATLAB, it summarized the advantage and the shortcoming of traditional edge detection operators, and the operating environment. On the basis of the experimental analysis, it implemented an edge location more precise, more efficient operating speed edge extraction method——Template Vector. In this method, it optimized differential approximate calculation of first differential operators the paper mentioned. After experimented on this edge extraction method, contracted with the traditional methods, the edge outline is extracted more accurately and more exquisitely, furthermore, it retained the object outline furthest, and achieved more satisfied edge extraction result.

其次，对图像分割领域中常用的基于边缘的分割方法进行了详细的研究与分析，对各种边缘检测算子进行了MATLAB环境下的实验，分析总结了各种传统边缘检测算子的优缺点和适应环境，并针对传统边缘检测算子在处理显微图像时的缺陷，在实验分析的基础上研究并实现了一种边缘定位更加精确、运算速度更加快捷的边缘提取方法——模板向量算法，在该算法中，对文章提到的一阶微分算子中微分的近似计算作进一步优化，经过对该边缘提取方法进行实验，其结果与传统方法相比，轮廓提取更为精确细腻，且最大程度的保留了图像中物体(目标个体或者明显噪声点)的轮廓，得到了比较理想的边缘提取效果。

Considered the inside and outside contour line was Archimedes spiral in the cold rolling, the forming law of rectangular cross sectional rings has been studied. And the more precise geometrical models and calculation models have been gained. The researches can be used as a theoretical and experimental foundation for the simulation of ring rolling process. At the same time, the results of theoretical analysis have a good agreement with the results of practical rolling production.

本文在考虑冷轧过程中环件的内外轮廓线均为阿基米德螺线的情况下，对矩形截面环件的轧制成形规律进行了研究，得到了较精确的几何模型和计算模型，为环件轧制过程的模拟提供了理论依据和实验依据，同时理论分析的结果与实际轧制生产过程中的结果有较好的吻合。

Chapter two, the theoretical basic of the metacongnition in Physics, stating that the theory of Autobus instructive study and the theory of architectural study, Piaget basic constructional learning theory and Vygotsky Social Construction are the psychological base of the metacongnition in Physics teaching, while Lifelong Education Theory and the Theoretical Research of the Subjectivity Education are the pedagogy basic of the metacongnition in Physics teaching.

第二章是元认知物理教学的理论基础。阐明了元认知的基本理论，奥苏伯尔的有意义学习理论、以及皮亚杰的建构主义学习理论和维果斯基社会建构理论是元认知物理教学的心理学基础，终身教育理论、主体教育理论是元认知物理教学的教育学基础。

These two consist of Lenin's axiology of theoretical education, giving the reason of theoretical education.

这两者构成了列宁关于理论教育的价值论，回答了为什么要进行理论教育的问题。

the university thought politics theoretical teaching is carries on the thought theoretical education to the university student system the main channel and the battle position.

高校思想政治理论教学是对大学生系统进行思想理论教育的主渠道和主阵地。

Others are no theoretical research,unconvincing theoretical research,rigid education administrative system, correlative reform seriously lagging behind,bureaucratism in the administration,belittlement of rule by law.

经文献分析、调查访谈、个案分析和比较分析等综合研究，以及"实践-理论-制度"的研究过程，论文深入研究了"教育行政权行使有效性"这一教育法学领域的重要理论与实践问题。

It is also known as one of the most poisonous naturally occurring substances.

它也被称为一个最自然发生的有毒物质。

The greatest stress is found at the location on the cross section where V is the largest.

最大应力出现在横截面上V为最大的地方。