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《中国科学基金》2020,(2)
在移动通信中,信道的特性决定了移动通信系统的性能上限,而第五代移动通信(5G)信道模型就是5G系统设计与技术优化的基础。本文首先介绍了国家电信联盟(ITU)对5G的愿景,引出了5G在大带宽、多频点、空—时—频多维特性和复杂场景四个方面对信道建模的需求。其次,总结了课题组在5G信道建模研究的四维建模理论框架、高精度大带宽测量平台与应用场景、信道特性提取与建模三个方面的研究进展,着重分析了毫米波信道建模和大规模三维(3D)多输入多输出(MIMO)信道建模。最后,针对未来第六代移动通信(6G)的需求,展望了6G信道建模的四个研究方向,包括太赫兹信道建模、大维信道建模、天空地信道建模以及智能化信道建模。 相似文献
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三维建模是开发虚拟现实产品的过程中重要技术之一。在虚拟场景进行构造时,建模技术的日渐成熟已使得建模手段逐渐丰富,加之工具的辅助作用,也使得当前建模出现了众多版本与技术类型。文章在分析建模手段的基础上,针对3DS MAX建模技术进行了综合介绍,并在研究建模过程中的优化问题时,重点对模型优化技术展开了论述,以期能有效发挥3DS MAX建模技术的功能,促使模型的利用效率得到提升。 相似文献
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三维地质建模是定量化研究三维空间结构特征与变化规律的重要方法,已成为模拟分析地质现象与时空演变规律重要有效手段之一。本文从数据模型、建模方法、建模软件、不确定性及应用领域五个方面阐述了三维地质建模技术的研究现状,并对三维地质建模技术发展的提出相应建议。 相似文献
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传统的二维展示方法已经无法适应我国快速增长且结构日益复杂的电网建设与需求。随着计算机,数据采集等技术的不断进步,三维建模技术在电网中的应用日益广泛。三维建模能够直观,可视化的展现电力设备,描述电力设备周围的环境信息。本文结合相关工程经验,力图从电网三维建模技术方法入手,提出一整套满足行业应用需求的建模约束条件和构建方法。同时也对三维建模在电网中的应用进行了深入的探讨,研究通过此次研究,将有助于今后电网领域三维建模的应用,同时提供理论及实践依据,服务基于三维地理空间的电网信息化建设与管理。 相似文献
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笔者针对起动建模和启动特性计算问题,简要评述了现有的几种较为典型的启动建模仿真方法,包括基于简单三段积分法的建模方法、基于稳态共同工作线的建模方法和基于部件匹配技术的建模方法,并对它们进行了对比,指出了各自的优缺点和适用范围,最后给出了一种新的基于辨识技术的建模方法。 相似文献
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随着三维动画成为世界文化产业的经济热点,在三维动画技术应用领域里曲面建模的应用越来越广泛。对NURBS曲面建模和细分曲面建模特征清晰的分析,有助于曲面建模在三维动画技术中更好的得到应用。本文综合了非均匀有理B样条(NURBS)曲面建模、细分曲面建模技术等理论,提出自己的看法,为三维动画制作提供解决方案。 相似文献
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王敏 《科技成果管理与研究》2016,(9):67-67
“大型薄壁高精度搅拌摩擦焊设备技术研究”(2010ZX04007-011)系“高档数控机床与基础制造装备”科技重大专项课题,由中国科学院沈阳自动化研究所牵头承担。课题研发的大型薄壁高精度搅拌摩擦焊设备,通过机器人辅助机构及相关技术的开发,突破了大型薄壁高精度搅拌摩擦焊多项关键技术,提高了搅拌头焊接结构适应性、跟踪精度,保证了搅拌摩擦焊的接头质量。课题于2016年5月24日通过了正式验收。 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