张家港市南二环和金港大道交叉口交通仿真分析

本文针对张家港市南二环和金港大道交叉口交通仿真分析交通问题提出优化方案,将优化后的交叉口交通运行情况与优化前的交叉口交通运行情况通过交通仿真进行技术对比,说明优化效果,以平均延误时间量化评价交叉口优化前后的交通运行情况。     

交通信号控制系统的研究与设计

交通信号控制系统对于交叉口来说至关重要,是现代城市交通控制和疏导的主要手段。本文选取南阳市的五山大道与云岛大桥组成交叉口为研究对象,通过对该交叉口的几何结构、信号配时和交通流量进行调查后,利用信号周期算法Webster方法为该交叉口设计了新的交通信号控制方案。最后,利用Vissim仿真软件对新旧控制方案进行了比较,得出新的控制方案在延误、停车率和通行能力方面都优于现在的控制方案。     

城市道路平而交叉设计

交叉口是道路的咽喉,相交道路的各种车辆和行人都要在交叉口处汇集通过.由于车辆和行人之间、车辆和车辆之问、特别是机动车和非机动车之间的干扰,不但会阻滞交通.而且也容易发生交通事故.因此,正确地设计交叉口并合理地组织交通,使车辆在交叉口的耽误时间减少,并保证车辆行车安全和提高交叉口的通行能力,就具有很重要的现实意义.     

城市道路平面交叉设计

交叉口是道路的咽喉,相交道路的各种车辆和行人都要在交叉口处汇集通过。由于车辆和行人之间、车辆和车辆之间、特别是机动车和非机动车之间的干扰,不但会阻滞交通,而且也容易发生交通事故。因此,正确地设计交叉口并合理地组织交通,使车辆在交叉口的耽误时间减少,并保证车辆行车安全和提高交叉口的通行能力,就具有很重要的现实意义。     

城市道路信号交叉口行人交通特性分析

行人交通分析是对交叉口进行合理科学的规划、改造的重要前提和基础,而分析行人交通的基础是对行人交通特性进行分析。本文在整理大量的调查数据基础上分析了行人过街速度特性和行人违章的成因,对信号交叉口行人交通特性进了研究。     

X型平面交叉口的渠化设计方案研究

X型交叉口是城市道路中平面交叉口的重要组成部分,它的通行能力是其组成干道交通运行能力的重要体现。通过对南宁市某一X型平面交叉口交通情况的调查与分析,并运用平面交叉口渠化设计的原则、方法及步骤,提出了该路口的渠化设计方案。     

浅谈城市道路环形交叉口交通组织的改造与优化

许多城市由于早期城市规划等各种问题,现状城市道路环形交叉口已不能满足飞速发展的交通需求,道路环形交叉口改造与交通组织优化越来越重要。文章简单介绍道路环形交叉口存在的问题,环形交叉口的改造与优化方案,进而提高交叉口通行能力。     

隧道式环行立体交叉

大城市中车辆日益增多,在乘车行经一般交叉口时,往往要化很多时间等候。据统计,因汽车制动、停车等候和起动所消耗的时间和燃料费用相当可观,所以在交通频繁的交叉口上设置立体交叉,使车辆不需交通管制而畅行无阻,互不干扰,是一个比较彻底、有效     

城市道路T型信号交叉口微观仿真研究

城市道路交叉口是城市道路系统中的重要的组成部分,交叉口的拥堵现象会影响交通的有效运行,提高交叉路口的通行能力对城市的交通有重要意义。利用VISSIM仿真软件对辽宁省鞍山市园林路——二一九路的T型交叉口的高峰交通量、信号配时进行模拟仿真,对仿真结果进行分析,提出优化方案。通过对比优化前后的行车延误、排队长度,验证了优化方案的有效性。优化后的配时方案缓解了交通压力,可以为城市信号交叉口的优化和通行能力的提高提供有效的参考。     

交叉口行人与非机动车过街问题及对策分析

交叉口作为城市道路交通系统的瓶颈,一直是道路交通组织和设计的研究重点。本文从交叉口行人与非机动车行驶过街的角度分析目前交叉口交通设计存在的问题,并从慢行交通、左转非机动车二次过街、因地制宜的过街设施、设置右转硬质渠化岛(交通岛)以及相应交通标志变现的设置等五个方面定性的分析其问题的解决对策,以期为后续的交叉口慢行交通设计提供参考。     

Low doses of a red wine ingredient figh diabetes in mice

Aresearch group led by Prof. ZHAI Qiwei from the Institute for Nutritional Sciences under the CAS Shanghai Institutes for Biological Sciences has discovered that even relatively low doses of resveratrol--a chemical found in the skins of red grapes and in red wine--can improve the sensitivity of mice to the hormone insulin, according to a report in the October,2007 issue of Cell Metabolism. As insulin resistance is often characterized as the most critical factor contributing to the development of Type 2 diabetes, the findings“provide a potential new therapeutic approach for preventing or treating” both conditions, the researchers said.     

Students' Reactions to the Introduction of Videoconferencing for Classroom Instruction

This study examined how students who had no prior experience with videoconferencing would react to the use of videoconferencing as an instructional medium. Students enrolled in seven different courses completed a questionnaire at the beginning of the semester and again at the end of the semester. Students at the origination and remote sites did not differ in their reactions toward videoconferencing but there was a significant difference for gender. Women reacted less favorably to videoconferencing. Compared to the beginning of the semester, students reported significantly less positive attitudes toward taking a course through videoconferencing at the end of the semester. There were no significant differences in students' attitudes toward videoconferencing across courses at the beginning of the semester but there were significant differences across the courses at the end of the semester. The results suggest the need for better preparation for both students and instructors.     

Molecular motor assembly of a biomimetic system

Active biological molecules and functional structures can be fabricated into a bio-mimetic system by using molecular assembly method. Such materials can be used for the drug delivery, disease diagnosis and therapy, and new nanodevice construction.     

Cooler temperatures inductive to locust outbreaks

Ajoint study by Prof. ZHANG Zhibin from the CAS Institute of Zoology and his co-workers from Norway, US and Swiss have indicated that historical outbreaks of migratory locusts in China were associated with cold spells, suggesting that China＇s projected climate warming could decrease the pest＇s numbers. The study was published in Proceedings of theNational Academy of Sciences on 17 September, 2007.     

Exploring Multiplexity: Social Network Structures in a Computer-Supported Distance Learning Class

A computer-mediated group is a complex entity whose members exchange many types of information via multiple means of communication in pursuit of goals specific to their environment. Over time, they coordinate technical features of media with locally enacted use to achieve a viable working arrangement. To explore this complex interaction, a case study is presented of the social networks of interactions and media use among members of a class of computer-supported distance learners. Results show how group structures associated with project teams dominated who communicated with whom, about what, and via which media over the term, and how media came to occupy their own communication niches: Webboard for diffuse class-wide communication; Internet Relay Chat more to named others but still for general communication across the class; and e-mail primarily for intrateam communication. Face-to-face interaction, occurring only during a short on-campus session, appears to have had a catalytic effect on social and emotional exchanges. Results suggest the need to structure exchanges to balance class-wide sharing of ideas with subgroup interactions that facilitate project completion, and to provide media that support these two modes of interaction.     

To serve and promote science development via innovation

CAS should stick to the principle of rendering service to, and giving impetus for, the development of China＇s science enterprise by making S＆T innovations, said CAS President LU Yongxiang. The CAS president made the remarks in a recent talk to communicate the gist of the winter session of the Party＇s Leading-member Group at CAS, which was held from 7 to 11 January in Beijing.     

Tracing the origin and early radiation of birds——Paleornithologist ZHOU Zhonghe

With great care, Dr. ZHOU Zhonghe takes out a package wrapped by cotton tissue from a drawer and says: "This is the gem of our collections: the fossil of a bird that lived 125 million years ago!" Then, pointing at a tiny mound, he explains: "Look, this is the claw and that is the head. It was in the egg shell and ready to hatch ... The species fell into a family of waterside inhabitants."     

The Role of Intermediating Institutions in the Diffusion of Electronic Data Interchange (EDI): How Industry Associations Intervened in Denmark, Finland, and Hong Kong

Electronic data interchange (EDI) provides means for interorganizational communication, creates network externalities, requires an advanced information technology (IT) infrastructure, and relies on standards. In the diffusion of such innovations, institutional involvement is imperative. Such institutions contain governmental agencies, national and global standardization organizations, local government, and nonprofit private organizations like industry associations. The last type of organizations we call intermediating institutions. They intermediate or coordinate ("inscribe") the activities of a group of would-be adopters. Unfortunately, little is known of how these organizations shape the EDI diffusion trajectory. In this article we examine one specific type of intermediating organizations?industry associations?and how they advanced the EDI diffusion process in the grocery sectors of Hong Kong, Denmark and Finland. We identify six institutional measures, placed into a matrix formed by the mode of involvement (influence vs. regulation) and the type of diffusion force (supply push vs. demand pull), that can be mobilized to further the EDI diffusion. Industry associations were found to be active users of all these measures to varying degrees. Their role was critical especially in knowledge building, knowledge deployment, and standard setting. Furthermore, institutional involvement varied due to policy and cultural contingencies and power dependencies.     

The Information Environment and Universal Service

This essay focuses on universal service and the Internet as means to support social and political participation. The emphasis on access to telecommunications systems in conventional approaches to universal service is contrasted with access to content. A model of the information environment is described that accounts for the roles of content and conduit, both of which are necessary conditions to achieve true access. A method is outlined for employing information indicators to observe or measure the information environment.     

How Electronic Publishers are Protecting Against Piracy: Doubts About Technical Systems of Protection

The increasing prospects of digital piracy has prompted the perceived need by electronic publishers to adopt technical systems of protection, and governments to reform their copyright laws. This article is a preliminary study of the management of intellectual property by electronic publishers, defined as those involved in the production of online databases, and CD-ROMs. It focuses on three main issues: (1) how electronic publishers view the increasing threat of piracy; (2) the methods of protection employed to protect intellectual property in digital format; and (3) the importance of technological protection of intellectual property in electronic publications. The analysis is based on a sample of 23 UK electronic publishers. The interviews revealed an interesting assortment of protection methods and did not show that technological protection was a preferred way. Instead, the means of protection, in addition to copyright law, comprised niche markets, pricing, trust, bad publicity, and nontechnical and technical means.