中国联通网络引进UMTS900分析

简要介绍了UMTS900及其在全球的商用情况,详细论述了UMTS900关键技术,对中国联通网络引进UMTS900的可行性进行了深入分析,并结合网络现状提出了UMTS900部署建议。     

光传送网的发展及其应用探讨

先简单介绍了OTN技术发展现状,然后通过描述OTN组成、特点、技术优势,进一步分析了OTN设备类型及组网选择,最后对OTN技术应用定位及应用场合进行了探讨.     

The multiple selections of fostering applications of hydrogen energy by integrating economic and industrial evaluation of different regions

There are three major applications (portable, stationary, transportation) of hydrogen energy (HE), and each application play a unique and important role in the sustainable development of energy system. In different regions within a country, different applications of HE are preferred. This paper therefore explores the process to decide the optimal region to develop each of the three subtypes of HE applications. To this end, the Analytical Hierarchy Process (AHP) and a fuzzy Technique the Order of Preference by Similarity to Ideal Solution (TOPSIS) method are used in the present study. Based on a literature review and in-depth interviews with officers, experts, the managers of HE-related enterprises, and consumers, the present study comes up with two selection criteria, namely, the acceptance on the applications of hydrogen energy (i.e., market entry barriers and customer's acceptance), and the integrity of hydrogen energy industrial chain on three applications (i.e., production stage, distribution stage, and marketing stage). This paper uses a case study to explore the functioning of three applications of hydrogen energy in the industrial, cultural and restricted residence regions. Four main findings emerges from this study: (1) the market structure of the portable, stationary and transportation application of HE should be pure competitive, oligopolistic, and monopolistic competition respectively; (2) the customer's acceptance for different applications is different, due to different neighborhood concerns about the quality of life; (3) the cost and benefit of different applications depend on different factors, including government policy, technological improvements and social preferences; (4) in order to promote all HE applications, the process to decide the optimal region to develop a specific HE application depends on the comparative advantages of the application.     

抓住机遇深化改革实现成人高等教育的可持续发展

21世纪是终身学习和继续教育的世纪,成人高等教育的发展面临新的机遇,同时也需面对新的挑战.要实现成人高等教育的可持续发展,必须进一步发挥成人高等教育的优势,创新观念,深化改革,办出特色.     

冷箱分离系统低温区的两种膨胀制冷流程分析比较

介绍了丙烷脱氢装置中冷箱分离系统低温区两种膨胀制冷流程,一种是饱和气体膨胀制冷流程,另一种是复热气体膨胀制冷流程。通过模拟分析,比较了2种制冷流程在制冷量、安全稳定性、分离效果等方面的情况,介绍了复热气体膨胀制冷流程的优点。     

Recent research progress on polymer electrolytes for dye-sensitized solar cells

Dye-sensitized solar cells (DSSCs) have attracted large attention due to their easy fabrication, low cost and high conversion efficiency. Electrolytes play an important role in the photovoltaic performance of the DSSCs and many efforts have been contributed to study different kinds of electrolytes with various characteristics such as liquid electrolytes, polymer electrolytes and so on. Because the leakage and the volatilization of liquid electrolytes hinder their practical applications in the DSSCs, polymer electrolytes with high ionic conductivity, excellent thermal stability and long-term stability of the DSSCs based on them are alternatives to liquid electrolytes especially for the quasi-solid-state DSSCs. In this paper, research on solid polymer electrolytes is summarized and the influence of salt concentration on ionic conductivity of solid polymer electrolytes is described and thoroughly explained. On the other hand, the advantages of gel polymer electrolytes (GPEs) are introduced. The factors affecting the ionic conductivity of GPE and the performance of their DSSCs, consisting of the polymer concentration and type, the iodide salts, the solvents and the temperature are discussed. The tendency and the reasons of their influence are expounded in detail. To enhance the properties of GPE, many strategies are taken such as the fabrication of porous structure in the GPE membrane, the incorporation of proton donors, the introduction of inorganic nanoparticles and the addition of pyridine derivatives. Their improving effect and the causes for the enhancement are set forth.     

生态旅游实施措施与利弊分析

详细论述生态旅游的基本概念与特征,简明扼要地提出了实施生态旅游的措施,同时客观地分析了我国实施生态旅游的利弊。     

浅谈有机化学双语教学利弊及相应对策

本文从授课教师及学生两个方面阐述了双语有机化学教学的利与弊,认为开展得当的有机化学双语教学有利于提高学生对有机化学专业知识和英语的双重掌握及使用,并针对双语有机化学教学过程中出现的一系列问题给出了相应的具体对策。     

浅谈联网型风机盘管系统在工程中的应用

众所周知，空调能耗在建筑能耗中所占的比重最大。风机盘管联网系统由于其预约控制、节能控制、防冻保护控制、时间表控制、远程控制、房间高低温度报警等众多优势，在空调领域得到了广泛应用。本文以中国大连高级经理学院宿舍为例，阐述了该系统的应用原理和优势。     

多电平电压型变频器(上)

在大功率领域,中点钳位三电平和H桥级联中压变频器应用最广泛,本文在详细讨论它们优缺点的基础上给出其主要适用场合,并分别介绍了它们各自的改进方案。文中还介绍了三种较少应用的多电平变换器:有源中点钳位三电平逆变器;电容钳位四电平变频器和在相支路中接入耦合电抗的多电平变换器。