关于斜单轴太阳能跟踪器的轴承简易密封问题

针对现有斜单轴太阳能跟踪器的转动轴承缺少有效的密封保护措施的现状,提出了一种简易的轴承密封保护方法和密封保护装置,并介绍了该密封保护装置的原理、结构和特性。     

斜单轴太阳能跟踪装置

提高太阳能发电效率,一方面研发新材料的太阳能板,另一方面提高转换效率;太阳能跟踪装置是解决办法之一。太阳跟踪装置是一种能够保持太阳能电池板随时正对太阳,使光线随时垂直照射太阳能电池板的动力装置,主要功能是实现光伏电池输出功率最大化。斜单轴太阳能跟踪系统主要包括:光强检测模块、控制器、白天黑夜检测模块、步进电机及驱动模块、支架等系统组成。     

斜靠式拱桥设计关键影响因素分析

为研究斜靠式钢管混凝土拱桥的结构受力特点,以一座拟建的90m斜靠式拱桥为例,分析了其主要结构参数(矢跨比、吊杆间距、斜拱倾角)对结构静力性能的影响。经过结构参数对比计算分析发现:当矢跨比由1/5变化至1/6时,内力值将出现较大幅度增加;吊杆间距的增大对斜拱受力不利;倾角的减小对主拱、系梁和斜拱受力不利。分析结果为斜靠拱设计提供了结构参数选取的建议,为此类桥梁的设计提供有利的参考。     

大倾角厚煤层柔掩支架采煤关键技术分析

通过单腿支撑柔掩支架采煤法成功地解决了支架在大倾角煤层中顺利下放的问题,具有很好的适应性;利用柔掩侧放煤技术解决了厚煤层一次采全高的问题,有效地回收煤炭资源。通过井下生产实践,表明单腿支撑柔性掩护支架采煤法和侧向放煤技术相结合是开采大倾角厚煤层一个新的、有效的采煤方法,打破了传统的单一俯伪斜柔性掩护支架开采的框架及巷道布置方式,建立起新的采煤系统,提高了资源的回收率,其回收率达到93.8%。     

大倾角厚煤层柔掩支架采煤技术

通过单腿支撑柔掩支架采煤法成功地解决了支架在大倾角煤层中顺利下放的问题,具有很好的适应性;利用柔掩侧放煤技术解决了厚煤层一次采全高的问题,有效地回收煤炭资源。通过井下生产实践,表明单腿支撑柔性掩护支架采煤法和侧向放煤技术相结合是开采大倾角厚煤层一个新的、有效的采煤方法,打破了传统的单一俯伪斜柔性掩护支架开采的框架及巷道布置方式,建立起新的采煤系统,提高了资源的回收率,其回收率达到93.8%。     

大倾角厚煤层柔掩支架采煤关键技术分析

通过单腿支撑柔掩支架采煤法成功地解决了支架在大倾角煤层中顺利下放的问题,具有很好的适应性;利用柔掩侧放煤技术解决了厚煤层一次采全高的问题,有效地回收煤炭资源.通过井下生产实践,表明单腿支撑柔性掩护支架采煤法和侧向放煤技术相结合是开采大倾角厚煤层一个新的、有效的采煤方法,打破了传统的单一俯伪斜柔性掩护支架开采的框架及巷道布置方式,建立起新的采煤系统,提高了资源的回收率,其回收率达到93.8%。     

大倾角厚煤层柔掩支架采煤关键技术分析

通过单腿支撑柔掩支架采煤法成功地解决了支架在大倾角煤层中顺利下放的问题,具有很好的适应性;利用柔掩侧放煤技术解决了厚煤层一次采全高的问题,有效地回收煤炭资源,通过井下生产实践,表明单腿支撑柔性掩护支架采煤法和侧向放煤技术相结合是开采大倾角厚煤层一个新的、有效的采煤方法,打破了传统的单一俯伪斜柔性掩护支架开采的框架及巷道布置方式,建立起新的采煤系统,提高了资源的回收率,其回收率达到93.8%。     

一般位置直线段实长及倾角讲解方法的探讨

从观察日常生活中诸多部件或零件开始,引出一般位置直线实长及其对投影面倾角求解的必要性,给出由投影求出一般位置直线的实长及其对投影面倾角及直线与投影轴夹角的方法,总结实长、倾角和夹角的求解规律。而后通过几个典型习题的作图过程分析,加深学生对定理的理解。几轮讲述表明：采用该种形式学生不仅能够快速掌握直角三角形法,而且也能激发学生学习工程制图的兴趣。     

大倾角厚煤层柔掩支架采煤关键技术

长沟峪煤矿通过单腿支撑柔掩支架采煤法成功地解决了支架在大倾角煤层中顺利下放的问题,具有很好的适应性;利用柔掩侧放煤技术解决了厚煤层一次采全高的问题,有效地回收煤炭资源．通过井下生产实践,表明单腿支撑柔性掩护支架采煤法和侧向放煤技术相结合是开采大倾角厚煤层一个新的、有效的采煤方法,打破了传统的单一俯伪斜柔性掩护支架开采的框架及巷道布置方式,建立起新的采煤系统,提高了资源的回收率,其回收率达到93．8％。     

轮廓位置误差补偿方法研究

轮廓加工中存在的电气、机械延迟、系统参数不确定性及两轴驱动系统参数不匹配等因素的影响,提出了增益误差辅助补偿零相差前馈跟踪控制器(K-ZPETC)与交叉耦合控制器(CCC)相结合的控制策略对两轴的运动进行协调控制来减小轮廓误差。并采用专家PID控制增益K使系统实现准确跟踪,减小了跟踪误差;CCC作用于两轴之间,用以增加两轴间的匹配程度,以减小轮廓误差。仿真和实验结果表明所提出的控制方案具有较好的跟踪性和鲁棒性,进而大大提高了轮廓精度。     

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.