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研究钢筋混凝土框架建筑结构的工程造价约束与建筑体抗震强度关系模型,设计最佳工程造价与抗震强度关系配比,对提高建筑物的抗震能力,降低土建造价各项费用具有重要意义。传统模型构建中,在给定建筑材料配比总可靠度条件下进行框架结构优化设计,没考虑框架结构的多阶段决策离散变量,导致分析精度和配比不合理。提出一种基于决策约束的框架建筑体的造价约束与抗震强度关系模型,设计典型的高层框架建筑体结构,优化框架建筑体的梁、柱截面尺寸选材,得到高层框架建筑体的造价约束横向计算单元模型。通过多阶段决策约束算子,得到造价约束下的最大可靠度约束函数。实验分析得出,每平方米造价增加比例不超过5.3%,房屋抗震设防水准可提高一个等级,通过模型构建,优化建筑配比,减少成本开支的同时提高了建筑质量。 相似文献
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单跨框架是一种抗震严重不利体系,缺乏冗余约束,易发生整体倒塌。单跨框架结构大量存在于中小学建筑中,汶川大地震后中小学建筑已提高到乙类设防,根据抗震鉴定标准《建筑抗震鉴定标准》（GB50011-2010）规定重点设防类的框架结构不得采用单跨框架结构,否则需进行加固。针对单跨框架的震害特征,探讨了该类结构的各种加固方法,本文结合一个工程案例进行了不同加固方法的比较,提出了提高单跨框架抗震能力的加固策略。 相似文献
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目前我国存在着大量抗震设防、抗震性能欠佳的建筑物,为了能够确保这些建筑安全使用并发挥其应有的建筑功能,要对其进行抗震鉴定及加固。本文分析了我国建筑物的抗震加固技术方法,对优于传统抗震加固方法的隔震加固方法进行了重点分析,并指出隔震加固方法更加适合现代建筑的抗震设计。 相似文献
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我国是一个多地震的国家,地震频率高,强度大且分布范围广。地震往往导致很多公路桥梁发生大规模的损坏,给抗震救灾带来巨大的困难。尤其是汶川地震的发生,使得桥梁设计工作者对桥梁结构在地震作用下的稳定性及通行能力提出了更高的要求。本文分析了桥梁震后检测加固的必要性,震后公路桥梁快速检测与评估技术,提出了各种抗震加固方法,以尽快提高我国桥梁抗震加固的技术水平,确保公路工程各结构具有足够的抗震安全度。 相似文献
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钢筋混凝土框架虽然抗震性能良好，但遭遇地震仍有可能发生损坏或倒塌。结合以往震害调查资料，本文分析了钢筋混凝土框架结构的震害类别、震害原因及震后修复加固的原则，最后结合实例阐述了框架结构的震后修复加固方法，可供参考。 相似文献
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斜张桥的抗震设计,是世界各国桥梁工程师都非常关心的重大技术难点问题。随着大跨度桥梁的发展,人们对结构的抗震越来越重视,对大型结构的抗震性能要求作专题研究,以确保结构的安全性。而且近年来经历了多次强震后,从这些大地震中的结构震害,使人们对以前的抗震设计方法进行了反思,对以前的抗震设计规范进行修改。本文将简要介绍各国桥梁抗震规范中的设计思想以及主要的设计方法。 相似文献
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斜张桥的抗震设计,是世界各国桥梁工程师都非常关心的重大技术难点问题。随着大跨度桥梁的发展,人们对结构的抗震越来越重视,对大型结构的抗震性能要求作专题研究,以确保结构的安全性。而且近年来经历了多次强震后,从这些大地震中的结构震害,使人们对以前的抗震设计方法进行了反思,对以前的抗震设计规范进行修改。本文将简要介绍各国桥梁抗震规范中的设计思想以及主要的设计方法。 相似文献
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《科技通报》2017,(5)
地下空间是一种宝贵的土地资源,在空间扩展的同时也应对抗震性能进行优化设计。因此文中以地下空间为研究对象,提出基于抗震可持续性的地下拓展空间可控规划设计。首先,运用有限元分析方法对地下建筑结构整体及土体进行地震反应分析,在考虑无限元边界条件下,先确定单元网格的划分,利用完全Newton迭代法确定影响结构动力分析的积分步长及阻尼系数,并给出合适的地震波系数,综合以上条件初步完成对低丘陵地区地下建筑的抗震分析过程;其次,将退火机制的微粒群理论与地下空间规划进行结合,在存在数量较多的空间规划单元、多种空间条件及多目标条件约束下,设定一个"粒子"为一个优化方案,利用土地空间协调性、空间规划类型约束和距离约束等方面,对土地空间规划情况建立目标函数并实现"粒子群"优化评价过程,从而获取地下拓展空间可控规划最优设计。实验证明,对地下空间的有效规划可减缓城市压力。 相似文献
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A research 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 in red wine-can improve the sensitivity of mice to the hormone insulin according to a report in the October issue of Cell Metabolism.…… 《中国科学院院刊(英文版)》2008,22(1):14-15
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. 相似文献
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Marjorie Armstrong-Stassen Margaret Landstrom Ramona Lumpkin 《The Information Society》1998,14(2):153-164
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. 相似文献
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A joint study by Prof. ZHANG Zhibin from the CAS Institute of Zoology his co-workers from Norway US 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 the National Academy of Sciences on September .…… 《中国科学院院刊(英文版)》2008,22(1):6-7
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. 相似文献
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Caroline Haythornthwaite 《The Information Society》2001,17(3):211-226
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. 相似文献
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Active biological molecules 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 therapy new nanodevice construction.…… 《中国科学院院刊(英文版)》2008,22(1):22-22
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. 相似文献
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《中国科学院院刊(英文版)》2008,22(1):2-3
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. 相似文献
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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. 相似文献
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《中国科学院院刊(英文版)》2008,22(1)
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." 相似文献
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Leah A. Lievrouw 《The Information Society》2000,16(2):155-159
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. 相似文献
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Puay Tang 《The Information Society》1998,14(1):19-31
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. 相似文献