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时滞相关Logistic函数浮点数据模糊加密稀疏集构造 总被引：1，自引：0，他引：1
提出一种基于时滞相关Logistic函数线性调频采样的浮点数据模糊加密算法优化技术,给出时滞相关Logistic函数及相关定义,研究了浮点数据的模糊编码算法,设计实时交互网络的浮点数据模糊加密方案,实现密钥稀疏集构造,采用基于稀疏矩阵的存储格式下的时滞相关Logistic函数浮点数据加密运算,构造密钥稀疏集,优化了算法性能。仿真结果表明,算法数据加密和解密性能较好,具有较高的数据吞吐量,能实现对大数据库的数据加密,提高了密文的不可预测性。 相似文献
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基于泊松方程第一类的边值问题求解,提出基于有限差分法的泊松方程第一类边值问题求解的方法。采用差分格式对边界条件下的泊松方程进行离散,在圆形的区域内进行网格的划分,利用有限差分法对泊松方程边值问题进行求解,经过算例的模拟试算,对有限差分法与四阶差分格式的近似解以及误差进行对比,结果表明,有限差分法的误差较小,求解的精确度较高,并且加速的性能较好。 相似文献
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小区间内分类数学模型是否具有模糊收敛性是处理数学问题分类的关键。对该类数学问题进行建模,验证了小区间内数学分类问题具有可行性和模糊收敛性。通过一种相位重组近邻点收敛的小区间分类算法,分析小区间特征数据点之紧邻点的收敛价值权重,过滤少数局部最佳特征数据的干扰,促进小区间分类数据近邻点的收敛性,提高数据分类收敛速度,采用马维尔条件对小区间数据分类解集进行约束,确保小区间分类模型的不动点存在且收敛,根据马维尔不动点定理得到,不动点产生的上下边界的解集中存在极限点,采用马维尔条件对小区间内分类数学模型的模糊收敛性进行验证。仿真实验对三类实际采集数据集进行模型验证,结果说明模型具有模糊收敛性。 相似文献
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泊松回归模型常常用于计数数据的研究中,然而在实际数据中零值的比例可能远远大于泊松分布中取零值的概率,而且这些零值通常都有其特殊含义.此外计数数据可能是分组数据,即观测到的数据不是确切值而只是已知其落在某一个区间范围之内;或者某些特定的数据,例如工资,要先对它进行人为的分组然后再进行分析.考虑一种零膨胀泊松半参数回归模型来处理上述分组计数数据.该模型中泊松分布的期望与协变量之间采用部分线性连接函数,而零值的概率与协变量之间采用线性连接函数.利用Sieve极大似然估计方法来估计该回归模型中参数和非参数函数,并提出了一种得分检验方法来检验是否存在零膨胀.在一定正则条件下,获得了Sieve极大似然估计的渐近性质,证明了参数部分的估计是强相合,渐近正态及渐近有效的;同时非参数函数的估计达到了最优收敛速度.模拟研究表明,估计和检验方法效果都比较好,最后将此模型和推断方法应用于一组公共卫生领域实际数据研究. 相似文献
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量子通信中的密钥设计是整个量子通信系统安全性的重要保障,传统的密钥设计方法采用固定密钥,无法实现变密钥加密,所以密钥和通信内容被破解的概率很高。提出一种基于色散评价的量子通信变密钥混沌加密实现方法,每次通信时,从混沌学的角度提取所有待通信数据的深层次特征,然后形成本次通信的加密和解密密钥,随通信内容的不同,系统密钥实时变化,在接收端,通过密钥和通信内容的混沌匹配来实现解密,并采用色散特性对加密效果进行评价。通过一组通信内容进行混沌加密性能测试,结果显示,基于色散特性衡量下的混沌加密特性安全性较传统方法大大提高,加密文本被破解的概率是0.0011%。 相似文献
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基于GPS的动态载体定姿算法具有重要意义。其关键是整周模糊度的快速求解,但采用直接收敛法求解双差整周模糊度的初始化时间过长,在实际中难以应用。LAMBDA算法通过模糊度浮点解及其方差协方差矩阵可以有效地估计整周模糊度,但动态情况下无法直接求得浮点解的方差协方差矩阵。本文提出一种估计方差协方差矩阵的方法,使得LAMBDA算法能够有效地应用到动态姿态测量中。实际算例表明,该算法可将初始化时间缩短到原来的1/2左右,能够高效地用于实时动态姿态解算。 相似文献
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双曲方程的稳定解分析方法在现代数学应用中具有广泛的意义。采用时齐马氏链进行双曲方程稳定解存在性分析具有模型匹配度高的优点。构建时齐马氏链的双曲波动方程,设计自组织非光滑时滞的双曲系统,结合时齐马氏链渐进性条件下的Lyapunov-Krasovskii泛函算法,对时齐马氏链渐进性条件临界阈值确定,以有效分析双曲方程的稳定解存在性,提高并行算法处理效率,在一阶非光滑时滞系统中得到方向性时齐马氏链函数的分解特征。研究证明,时齐马氏链渐进性条件下,双曲方程存在稳定性解,解向量在有限时间内收敛。 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