基于叠加编码的Web网页抓取路径损耗估计

对Web网页抓取是实现Web文本特征数据检索的最佳方式,Web网页抓取路径损耗误差的优化估计可以提高对Web数据的挖掘性能。传统方法中,对Web网页抓取采用基于线性滤波检测的单模匹配抓取方法,受弱信号幅度和临界阈值约束,路径损耗较大,且无法有效实现路径损耗误差有效估计。提出一种基于叠加编码特征统计的Web网页抓取路径损耗误差估计算法。构建Web网页文本特征抓取的目标函数,进行Web网络路径损耗模型构建,设计叠加编码算法进行特征统计,得到Web网页抓取路径概念格。仿真实验表明,该算法能有效提高Web网页抓取路径损耗误差估计精度,进而提高了Web网页文本数据抓取的查准率和文本特征数据的挖掘性能。     

基带回波扩散参数AT-Tree模式挖掘实现

对高速运动目标的基带回波扩散参数的准确估计和挖掘是实现目标信号检测和参量估计的重要内容。高速运动目标在发射脉冲是产生多普勒扩散,导致在速度模糊的情况下对基带回波参数估计困难。提出一种基于AT-Tree模式挖掘模式的运动目标的基带回波扩散参数估计算法。构建高速运动目标信号模型和目标多普勒扩散模型,基于AT-Tree模式进行基带回波随机过程分析,建立项的平均概率值得到AT-Tree树型结构,将有序的项集添加到AT-Tree上,实现对基带回波扩散参数的挖掘和估计,在分辨力足够的前提下,对参数实现高分辨搜索,提高挖掘性能。仿真结果表明,该算法能使高速运动目标的基带回波调频信号在分数域上能形成明显的能量积聚,形成一个冲激函数,基带回波扩散参数的数据挖掘的精确度较高,精度较好,在制导参数估计和目标检测等领域应用价值较高。     

异质网间通信信道单谱脉冲响应频率估计

提出一种基于Hough变换的单谱特征分析的异质网通信信道脉冲响应频率估计算法。采用正交频率复用OFDM训练起始帧,加入多径分量的相位偏移进行相位偏转修正,构建了信道模型与脉冲响应信号模型。频率估计中采用Hough变换把信号空间中的直线的检测问题转换为参数空间中对点的检测问题,计算多普勒单谱脉冲响应信号的约束经验模态值,实现Hough变换单谱脉冲信号检测和脉冲响应频率估计算法改进。仿真实验表明,该算法能准确估计出异质网间通信脉冲响应信号的频率值,精度较传统方法高,在最小的迭代步数下实现算法收敛,误码率为0,性能较优。     

强干扰多载波雷达信号幅度检测算法

在强干扰环境下对多载波雷达信号的幅度检测是实现空中目标打击的关键技术。传统方法中,对雷达信号的幅度检测采用时频耦合算法,如果信号和背景噪声有很强干扰和多载波特征时,检测性能不好。提出一种基于分数阶Fourier时频耦合的信号幅度检测算法。构建强干扰环境,描述雷达信号的宽度和深度等特征量,对多载波雷达信号进行分数阶Fourier变换,对目标回波的尺度和时延进行估计,求解相位模糊数搜索结合解,得到雷达信号参数相位补偿结果,根据雷达信号特征量聚点塑造特征量模型运算雷达信号的特征量聚点,获取高特征量聚集区域,通过后置的高阶累积量切片,使信号的累积量增大,而噪声被抑制提高了检测精度。仿真实验表明,算法的检测概率较高,幅度检测能很好地跟踪信号幅度的变化。     

移动云计算中的时变通信信道估计算法

在移动云计算中,通过无线通信方式实现数据调度和传输,移动云计算通信信道具有时变特性,对其有效的信道均衡和相位估计是保证云计算质量的基础。传统的时变通信信道估计算法采用多模盲均衡算法,出现码间干扰和相位失衡。提出一种基于二次调频双稳态检测的移动云计算中的时变通信信道估计算法。首先进行移动云计算的通信信道模型构建,基于协议信道邻居构建的通信功率增益模型,进行信道划分协议设计,设计二次调频双稳态检测算法,采用同步算法减少系统子载波间的正交性抑制,得到移动云计算通信系统信道均衡系统,检测移动云计算信道的时变特征,实现准确估计,通过仿真实验进行性能验证。仿真结果表明,该算法具有较大的信道估计性能,抗干扰能力提高,信息增益提高,在云计算通信中具有较好的稳健性。     

频域徙动运动参数闭频繁项集挖掘算法

高速多目标运动状态监测过程,运动参数的频域徙动导致参数估计和挖掘困难,传统方法对高速频率徙动运动目标参数的挖掘采用MapReduce框架的并行FP-Growth算法,算法需要对运动目标的速度和加速度进行预估计,实现困难。基于多普勒扩散的项集期望支持数模型,提出一种改进的基于闭频繁项集挖掘的高速多目标的运动参数挖掘算法,构建高速多目标运动参数信号模型,采用普勒频率模糊数搜索的方法完成高速多目标的频域徙动动态平滑,准确挖掘出运动参数的相位、时延、速度和频率等相关信息。研究结果表明,该算法能准确拟合时延、速度等运动参数,拟合值与真实值相同,对高速运动目标的运动参数估计精确,在高速运动目标参数挖掘和精确制导等方面具有较高的应用价值。     

引入合同变换矩阵的网络攻击信号盲分离算法

对网络攻击信号进行盲分离,实现对攻击信号的准确有效检测。传统的网络攻击信号检测算法使用时频分析方法,提取非平稳群攻击信号的时频特征,实现信号检测,但算法把网络入侵检测正确率作为约束目标函数进行同步最优特征子集求解,复杂度较高,提出一种引入合同变换矩阵的网络攻击信号盲分离算法。采用时频分析Viterbi算法,得到信号谱的平均频率等于瞬时频率的时间平均,根据合同变换矩阵,对攻击信号进行离散数据解析化处理,构建网络攻击信号的解析模型,得到网络统计信号在多复变边界条件下的时频特征,实现盲分离算法改进。仿真实验表明,该算法能有效实现对网络攻击信号的盲分离,盲分离结果能准确反映网络攻击信号的内部特征,提高了对网络攻击信号的检测能力,对攻击信号的检测性能有所提高,保证了网络安全。     

改进的混响数据分段Itakura距离估计算法

在主动探测自导系统设计中,混响数据分段Itakura距离的准确估计是实现自导系统测距,提高目标信号检测性能的基础,且Itakura距离可以评价对混响数据的局部平稳性。当前的混响数据Itakura距离估计算法采用基于局部高斯色噪声混响估计模型,当相邻数据段与需检测信号脉宽一致时,距离估计精度不好。提出一种基于Rayleigh分布分段副本相关检测的混响数据Itakura距离算法,构建混响数据包络模型实现对混响包络概率分布特征的准确描述,采用基于频率选择性衰落的自适应噪声抵消算法对混响数据包络模型进行简化,对混响数据进行Rayleigh分布下的概率密度特征分割,设计分段副本相关检测器,计算该组数据中相邻数据段之间Itakura距离,实现目标Itakura测距。实验结果表明,改进算法对Itakura距离估计精度较高,局部平稳性影响较小。在精确探测制导等领域具有很好应用价值。     

持续性实时监测数据的无偏风险挖掘仿真

持续性实时监测数据的挖掘和调度常用在战场监控、森林火警监测等领域。在对持续性实时监测数据调度和挖掘中,因为战场监控、森林火警等持续性实时监测数据的挖掘中存在物理干扰,会产生时间延迟等风险,需要对其进行无偏估计和风险转化,提高数据的挖掘和实时监测性能。提出一种基于聚集树的持续性实时监测数据的无偏风险挖掘算法,并进行仿真实现。构建持续性实时监测数据的采集和预处理模型,进行监测数据的聚集树关联性分析,求得数据无偏相位特征,得到数据挖掘的最短无偏时延估计值,求得持续性实时监测数据的无偏风险挖掘最优路径无偏估计值。实验结果表明,该算法能有效避免数据挖掘过程中产生的时间延迟风险,通过无偏估计和风险转化,提高数据的挖掘和实时监测性能。     

衰落噪声干扰下网络攻击数据散布特征挖掘算法

提出一种基于随机近场混叠谱分析的网络攻击数据散布特征挖掘算法,实现对衰落噪声干扰下的网络攻击信号的准确检测。采用自适应陷波器对衰落干扰噪声进行滤波降噪预处理,提高了待检测信号的纯度,进行随机近场混叠谱分析,采用时频分析方法进行攻击信号的时延估计,提取随机近场混叠谱特征,实现网络攻击数据散布特征挖掘优化。仿真实验表明,采用该算法能有效提取在强衰落噪声干扰下的网络攻击数据时频散布特征点,特征聚焦性能明显,提高了对网络攻击数据的检测性能。     

Students' Reactions to the Introduction of Videoconferencing for Classroom Instruction

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.     

Cooler temperatures inductive to locust outbreaks

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.     

Exploring Multiplexity: Social Network Structures in a Computer-Supported Distance Learning Class

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.     

The Role of Intermediating Institutions in the Diffusion of Electronic Data Interchange (EDI): How Industry Associations Intervened in Denmark, Finland, and Hong Kong

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.     

How Electronic Publishers are Protecting Against Piracy: Doubts About Technical Systems of Protection

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.     

Rough Justice: A Statistical Assessment of ICANN's Uniform Dispute Resolution Policy

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.     

Prevalence of soft neurological signs in Chinese people

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.     

Monoculture Rubber Plantations Have Negative Ef ects on Controlling Splash Erosion

<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     

Chinese Scientists Use Earth Observation Technologies to Study and Protect Wild Camels

<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     

More than Skin Deep – Understand Skin Biology by Means of Dermatogenomics

<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.