Allocation of fixed transmission cost based on power flow tracing algorithm

1 Introduction a In the electricity market, because the calculation of the traditional spot electricity price according to node transmission charging is based upon short-run marginal cost, it is impossible to recover the great one-off investment of the transmission network, and this results in the payment imbalance of the electric network. Therefore, such spot electricity price goes against and its modification is indispensable to the development of the power system, and it is necessary to mod…     

搜索引擎的发展概况与趋势

搜索引擎是随着网上信息不断丰富应运而生的一种检索工具。1994年,Internet上诞生了第一个搜索引擎W ebCraw ler,通过对网页做索引来提供检索服务。2000年,Google的出现使搜索引擎市场发生了新的变化。近年来,中文搜索引擎的发展快,数量多。搜索引擎的发展有以下趋势:数据库小型化,专业化;强化全文检索功能;检索智能化、服务个性化;语种多样化;元搜索引擎的发展;搜索服务等。     

智能型搜索引擎研究

随着网络与通信技术的迅速发展,Web信息爆炸性的增长形成已经一个巨大的海量信息空间。如何快速、准确、方便地从如此庞大的信息库中获取自己需要的信息,是互联网用户面临的一个重要问题。Web搜索引擎能为用户提供一种查找所需资源的服务,已经成为互联网上仅次于电子邮件的第二大服务。首先介绍了搜索引擎和数据挖掘技术的概念,描述传统搜索引擎的局限性,然后介绍数据挖掘在搜索引擎中的应用及优点。最后,给出了搜索引擎的发展方向。     

集中式P2P社区算法研究

针对目前P2P系统资源所存在的带宽占用严重、搜索效率低下等问题，引入了P2P社区划分的方法，设计并实现了一种集中式P2P系统的社区创建、社区优化和社区维护算法，并通过Maze系统实验验证了社区算法的正确性和有效性.     

Sensitivity and precision of adverse effects search filters in MEDLINE and EMBASE: a case study of fractures with thiazolidinediones

Background: Search filters have been developed in MEDLINE and EMBASE to help overcome the challenges of searching electronic databases for information on adverse effects. However, little evaluation of their effectiveness has been carried out. Objectives: To measure the sensitivity and precision of available adverse effects search filters in MEDLINE and EMBASE. Methods: A case study systematic review of fracture related adverse effects associated with the use of thiazolidinediones was used. Twelve MEDLINE search strategies and three EMBASE search strategies were tested. Results: Nineteen relevant references from MEDLINE and 24 from EMBASE were included in the review. Four search filters in MEDLINE achieved high sensitivity (95 or 100%) with an improved level of precision from searches without any adverse effects filter. High precision in MEDLINE could also be achieved (up to 53%) using search filters that rely on Medical Subject Headings. No search filter in EMBASE achieved high precision (all were under 5%) and the highest sensitivity in EMBASE was 83%. Conclusions: Adverse effects search filters appear to be effective in MEDLINE for achieving either high sensitivity or high precision. Search filters in EMBASE, however, do not appear as effective, particularly in improving precision.     

不同级别项目团队科研人员信息查询行为特征与差异性

目的：评价不同级别团队科研人员的信息查询行为特征和差异.方法：采用自行研制的科研人员信息查询行为量表,调查所在学校承担国家级、省级、厅级、局级4个层面科研项目的36个团队218名科研人员的信息查询行为,并比较分析其信息查询行为特征和差异.结果：团队中不同性别、不同学历、不同职称科研人员的信息查询行为均存在显著差异,高职称的科研人员对信息查询行为最强;承担国家级科研项目的团队科研人员的信息查询行为最优.结论：应针对项目团队科研人员的信息查询行为水平,提高、增强科研人员的信息协作能力和信息素养,为其构建良好的信息资源环境.     

“Books.Google.RU”—Google's Mass Digitization of Russian‐Language Books

ABSTRACT. Google is pursuing “mass digitization” of Russian books as part of its efforts that now involve more than a dozen partners, although so far there is no separate Russian‐language search interface. How easy is it to find materials in books.google.com that are in Russian? What do users need to know to maximize their results?     

From Magicians to Teachers

Summary

Electronic reference is a large part of today's library. Computer technology has clearly been the dominant catalyst for change in library service over the last few decades. Reference service has changed along with the prevailing technology. An exclusive group of searchers serviced electronic information requests during the online searching craze of the 1970s and 1980s. In the library of today, this model of electronic reference is no longer operational. Electronic information is now available to anyone on a computer terminal. In response, all librarians have become familiar with computer technology, and have a new emphasis on teaching and basic information literacy. This article will examine how this came to be, and the technologies that helped make it happen.     

Student Responses to Using a Computerized Database

Summary

An overwhelming majority (94%) of surveyed students rely on assistance from librarians (80%), professors (9%), and friends (5%) when using ERIC-on-CDROM, even when they are not first-time users. Almost three-quarters of the students report that ERIC-on-CDROM improves research quality (74%) and learning (70%) and evokes feelings of motivation and accomplishment (72%). All students indicate that they will return to use ERIC-on-CDROM but only 39% feel capable of transferring their skills to similar databases. Responses indicate that ERIC-on-CDROM contributes to highly individualized learning situations in which students successfully find information through assistance from both humans and computers.