结构

With the support of a major research grant of Zhejiang Province (No. 001101027) and the Plan of Promoting Education of Excellence of Zhejiang University in the 21st Century, this dissertation is devoted to address the above problems and fabricate an L-band EDFA with low cost, high performance and technological innovation.First the mechanism of an erbium doped fiber amplifier is introduced. Various theoretical models based on classical rate propagation equations are summarized and compared for their applications. We use a modified numerical model based on the Giles model, which agrees with the experimental results well. This serves as the theoretical base for the whole thesis and will be used to optimize the characteristics of EDFAs. A novel method based on a map of noise figure and gain is proposed to analyze efficiently the dependence of the noise figure and gain for EDFAs on the EDF length and the pump power. The characteristics of various EDFAs are studied and compared.Secondly, some important parameters are introduced to describe the characteristics of EDFAs. The methods and the experimental setups for measuring the gain and noise figure of an EDFA are emphasized. We introduce how to measure the characteristics of each component of an EDFA, especially the gain and absorption coefficient of an erbium doped fiber.Thirdly, four types of simple and novel L-band EDFA structures with low noise, high gain and low gain ripple are proposed to satisfy the requirement of a DWDM system. They can be classified into two categories. In the first category, a single ASE pumping is served asa secondary pump. This category includes the following three types. Type: a new construction using a fiber Bragg grating in an unpumped EDF section at the input side. Type: a new structure of L-Band EDFA with two-stage pumps, which utilizes the forward ASE as a second pump.

本论文本着科技创新、服务于生产实践的精神，以设计价格低廉，性能优越、结构合理简单的L-band EDFA为目标，依托浙江省科技厅重大科学基金资助项目(001101027)和浙江大学振兴教育计划资助的全光网络的搭建—《光通信技术》课程实验建设项目，展开了如下工作：首先，介绍了掺铒光纤放大器的工作原理，归纳总结了基于速率方程基础的EDFA的各种理论模型，分析比较了各个模型的特点和适用场合，最终选择完善的Giles理论模型作为本论文分析设计EDFA的理论基础；针对实际实验条件提出了修正的EDFA模型的数值计算方法；创新地提出了增益—噪声系数全局分析法，直观有效地分析了EDFA的增益和噪声系数与掺铒光纤长度和泵浦功率的依赖关系，并对各种EDFA的性能作了全面的比较；第二，介绍了掺铒光纤放大器特性参数的定义与测量方法，重点介绍了噪声系数和增益系数的测量方法及实验装置；介绍了组成掺铒光纤放大器各组件的特性测量方法，重点介绍了测量掺铒光纤参数的方法和实验装置；第三，针对WDM系统对L-band EDFA谱平坦、低噪声、高增益的要求，我们创新地提出了四种不同的L-band EDFA结构，按设计思路可以分为两大类：一类是基于单抽运二级泵浦法，这一类包括在未泵浦掺铒光纤的输入端插入一根布拉格光纤光栅的两段L-band的EDFA的新结构；基于前向ASE光作为二级泵浦源推动下一级EDF工作的泵浦分配、两段级联L-band的EDFA的新结构；基于单根光纤光栅、泵浦分配、两段级联的EDFA；另一类则是基于同时应用前后向C-band ASE作二级泵浦源的双抽运法，如基于前后向ASE光作为二级泵浦源的三段级联L-band的EDFA的新结构。

Through thorough research, it first carries out a systematic review of the theory of industrial structure, evolves general rules from the industrial structure for structural rationalisation, functions and effects etc.

本文首先对产业结构理论进行了系统回顾，从产业结构演变的一般规律到产业结构合理化高度化的实现方式，产业结构的功能和效应等做了比较深入的研究，指出产业结构与经济发展密切相关、互为因果，即是经济发展的必然反映和结果，也是经济发展的动因。

Circumfusing recurrent structure,which is one of the basic structure of program designing,introduces the teaching method about recurrent structure from two way,elaborates the method of how to understand the meaning of recurrent structure quickly,summarizes common problems of recurrent structure and gives the corresponding technique of program designing.

针对程序设计语言中三大基本结构之一的循环结构，从两个方面探讨了循环结构的教学，阐述了如何让学生迅速掌握循环结构内涵的方法，归纳出需要用到循环结构编程的常见问题并给出相应的编程思路

The conduits are fabricated enlacing 2.2 millimeter stainless steel on the braiding machine with 16 spindles using 2700 Tex yarns .

共制作四种结构神经导管，分别为普通结构神经导管、编织线结构神经导管、加筋结构神经导管和加芯结构神经导管。

Parameter study of three-way guyed mast structure ;2. Damage detection method for vertical bars of mast structure in time domain;3. According to structural dynamic features of mast structure and the change of dynamic properties after damage modal analysis is applied for damage detection.

研究了桅杆结构的破坏原因和破坏机理，针对桅杆结构本身的结构动力特性和损伤后的动力特性改变，对应用模态分析方法在桅杆结构的损伤诊断的应用问题进行了分析，指出了模态分析的损伤诊断方法在桅杆结构中的应用方向。

Typical inflecting language such as ancient Greek, the sentence as the expressing unit of language is of strict and definite structural principle and closeness, however the word as the basic structural unit, is relatively not selfsufficient.

典型的屈折语，如古希腊语，句子作为语言表达的结构单位有着严格的确定的结构原则和结构封闭性，而基本结构单位词具有相对的非自足性，其外在形式随其在句子中的语法身份而变更，体现出受制于句子结构的一面。

This dissertation lucubrates the architecture of ATS, hierarchical structure and resource models of testing software and the physical structure of hardware.

主要成果是：（1）研究了 ATS 执行机制，首次提出了基于虚拟仪器测试引擎的开放式 ATS 体系结构，从根本上实现了 ATS 硬件无关性和测试代码重用性；（2）研究了采用 IVI、IVI-MSS 和组件技术实现 ATS 仪器互换性的技术与方法，对实现 ATS 网络化奠定了基础；（3）研究开发了测试流程描述语言及相关仪器描述模型、开关矩阵描述模型、测试适配器描述模型，实现了测试软件的结构化和模块化，使大型复杂武器装备测试系统的开发与维护效率大大提高；（4）研究了与 ATS 体系结构相适应的硬件物理结构，该结构实现了 ATS 的通用性、开放性和可扩展性。

And the lives near the tunnel also will be menaced by the threat of explosion.

爆炸时隧道衬砌结构的稳定性是隧道安全与周围结构物安全的基础，为了解在隧道内爆炸事故引发的衬砌结构动力响应规律，探讨隧道衬砌结构的损伤状况，对盾构隧道衬砌结构抗爆具有深远的意义。

Finally, through the instance of engineering, we can see that the steel dosage in steel honeycomb plank is smaller and the self-weight of the whole structure is lighter comparing with pyramided grid structure, and the steel dosage in portal strut with honeycomb laminated beam-column system is still smaller and the self-weight is still smaller comparing with steel I-beam,they will have a wide applied foreground.

最后，通过工程实例分析表明，在大跨度屋盖结构中，金属蜂窝板-杆空间结构体系比常规的四角锥网架结构具有用钢量低，结构整体自重轻等优点；在轻钢结构厂房中，采用金属蜂窝纯板片箱梁体系比一般H型钢结构用钢量更低，自重更轻，具有广泛的应用前景。

It introduces the concept of the agricultural structure; the concept of reasonable agricultural structure and characteristics; it rationalizes the signs and standards of the industrial structure of agriculture; it introduces the analysis of the agricultural structure.

第一部分农业产业结构合理性的基本理论；介绍了农业产业结构的概念；农业产业结构合理性的概念及特点；阐述了农业产业结构的合理化标志和标准；介绍了农业产业结构的分析方法。

Do you know, i need you to come back

你知道吗，我需要你回来

Yang yinshu、Wang xiangsheng、Li decang,The first discovery of haemaphysalis conicinna.

1〕 杨银书，王祥生，李德昌。安徽省首次发现嗜群血蜱。