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当前复杂的零件装配过程中,装配流程的步骤多达上千次,合理的装配顺序是高效工作的保证。提出一种基于考虑需求虚拟负责零件装配流程重新仿真方法。分析了复杂零件直接的装配关系。通过装配体层、子装配体层、零件层、零件特征层、零件几何层建立零件直接的装配关系模型。通过三维图像虚拟技术完成模型的重现。测试结果表明,采用三维图像虚拟复杂零件装配流程系统,可以对较为复杂的零件拆卸过程进行重现,对交叉装配过程的仿真过程也可以较好的实现。 相似文献
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在脸部残缺修补建模过程中,匹配图像无明显匹配关键特征,形成匹配错误,造成建立的三维人脸模型特征偏移。为了避免上述缺陷,提出了一种融入错误图像识别模型的脸部残缺修补三维建模方法。建立错误图像识别模型,从大量的脸部图像中识别出错误图像,从而为脸部缺损修补三维建模提供依据。根据采集的大量脸部图像,利用多目标三维重建技术,建立脸部缺损修补三维模型。实验结果表明,利用该算法进行脸部缺损修补三维建模,可以极大的提高建立脸部模型的真实度,降低了建模过程中的误差,取得了令人满意的效果。 相似文献
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三维地形可视化是虚拟环境漫游研究的一个重要问题,通常采用高精度网格简化算法来保留地形的细部特征,形成多分辨率网格以提高显示效率,但在简化过程中需要额外考虑消除裂缝、连接和误差度量等计算。文章采用了一种逆向方法,即基于图像纹理特征网格细分方法生成三维地形;将含有地形高程纹理特征的图像映射到一个规则初始网格模型中,根据三角边与它的纹理特征曲线相交情况来细分网格,从而也实现了多分辨率三维地形模型。该方法的主要特点是生成结果除了能够反映虚拟地形的细节特征外,无需考虑消除裂缝和连接计算过程。 相似文献
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本文首先分析了气囊的结构与柔性上排工艺的发展情况,具体建立了船舶气囊受压模型,最后分析了船舶气囊柔性上排工艺过程及下水运动受力情况。 相似文献
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运动员进行不同的运动项目时,关节所成的角度,运动速度有差异,造成特征捕捉点不能很好对应关键区域,形成特征凌乱对应误差,影响形状基计算的准确性。传统的体育运动图像三维重建算法,受到形状基凌乱的影响,后期建模准确性很难控制。因此提出随机体育运动图像捕捉点虚拟重建中凌乱误差控制算法。利用因式分解法,建立人体运动时的三维动态仿真模型,运用stolt变换将所有图像捕获点的的方位偏移率调整为相同,使其在进行特征匹配时不会产生过大误差,对于过大的凌乱残余误差,进行三阶运动补偿,实现人体运动图像序列中的三维动态仿真建模。实验结果表明,这种算法提高了人体运动图像序列三维动态仿真的真实性。 相似文献
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研究假肢虚拟再生仿真方法。腿部结构较为复杂,残缺再生过程需要根据不同腿部残缺根源部位进行方向和角度的预测,但是由于腿部角度和生长方向推断过程信息过少,造成传统的虚拟腿部残缺再生仿真无法取得足够信息,只能根据简单的向上,造成模拟效果不好。为此,提出了一种基于智能视觉的假肢虚拟再生仿真方法。根据误差四元数状态变换相关理论,能够对假肢虚拟再生的方向和旋转角度进行有效的预测,从而为假肢虚拟再生仿真提供准确的依据。根据双目立测三维模拟方法,建立假肢虚拟再生仿真三维模型。实验结果表明,利用该算法进行假肢虚拟再生仿真,可以真实的反映残肢不同位置特征点的相关性,从而为假肢虚拟再生手术提供依据。 相似文献
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为揭示产业集群的网络本质和复杂特性,采用供应链视角考虑区域中船舶制造产业集群的网络结构。根据船舶制造产业的特殊生产过程,论述区域中船舶制造产业集群的3个方面特征:需求拉动、复杂网络和核心企业。基于单一供应链构建区域船舶制造产业集群的基本网络模型,解释供应关系下基本网络中的企业链接;基于交叉供应链构建区域船舶制造产业集群的多重网络模型,论证模块化导致的网络结构变化。在此基础上,结合复杂网络理论说明区域船舶制造产业集群网络结构的有向加权网络特征、无标度网络特征和层次网络模块特征。 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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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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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
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Milton Mueller 《The Information Society》2001,17(3):151-163
Long-standing conflict between domain name registrants and trademark holders prompted the Internet Corporation for Assigned Names and Numbers (ICANN) to create a global, mandatory arbitration procedure known as the Uniform Dispute Resolution Policy (UDRP). The UDRP has been used in 2166 cases involving 3938 domain names as of 1 November 2000. The policy gives the initiator of a complaint, generally a trademark holder, the right to choose which ICANN-accredited dispute resolution service provider (RSP) will handle the case. During the preparation of the UDRP,some feared that complainant selection would lead to "forum shopping" that might bias the results. This article performs a statistical assessment of the forum-shopping thesis and finds support for it. There are statistically significant differences in the various RSPs' propensity to take away names from defendants; there are also major differences in the number of cases brought to each RSP. RSPs who take away names have the larger share of cases. The study examines other variables that might explain differences in market share, such as price, the plaintiff's nationality, or the time taken to decide a case. It finds that nationality and time also are correlated with market share. The study concludes that shopping for a favorable outcome is an important factor in the UDRP. 相似文献
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Prof. Raymond C.K. Chen a neuropsychologist with the CAS Institute of Psychology has made novel progress in his studies of schizophrenia. His work has been reported by a recent issue of Behavioural Neurology.…… 《中国科学院院刊(英文版)》2008,22(1):15-15
Prof. Raymond C.K. Chen, a neuropsychologist with the CAS Institute of Psychology, has made novel progress in his studies of schizophrenia. His work has been reported by a recent issue of Behavioural Neurology. 相似文献
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《中国科学院院刊(英文版)》2014,(3)
<正>In Xishuangbanna,one of China’s most biodiverse regions,landscape has changed dramatically during the past three decades due to the conversion of tropical rainforest to rubber plantations.In steep areas,terraces are often constructed before planting rubber trees,which causes two important changes in the soil:the destabilization of soil in the bench terraces and the increased vulnerability of unvegetated riser faces to erosion.Few studies have documented the nature and intensity of erosion on bench terraces.Prof.LIU Wenjie and his colleagues from the Xishuangbanna Tropical Botanical Garden(XTBG)conducted a study in Menglun County(21°5′39″N,101°15′55″E),Xishuangbanna to evaluate the influence 相似文献
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Chinese Scientists Use Earth Observation Technologies to Study and Protect Wild Camels 总被引：1，自引：0，他引：1
《中国科学院院刊(英文版)》2014,(3):267-268
<正>Chinese scientists plan to apply Earth Observation technologies to protect the critically endangered wild camels(Camelus ferus).With the help of remote sensing,satellite positioning,geographical information system and wireless sensors networks,they will be able to access the distribution and population of the wild camels and protect their habitats.The project will be carried out by the International Research Center for Wild Camel Conservation,which was jointly established earlier this year by the Institute of Remote Sensing and Digital Earth(RADI)of the Chinese 相似文献
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WANG Sijia 《中国科学院院刊(英文版)》2014,(2):192-194
<正>The Paul Gerson Unna Research Group on Dermatogenomics was founded in October 2012 at the Partner Institute for Computational Biology.The ultimate goal of the group is to understand the biology of skin and skin appendages. 相似文献