电厂热工测量误差的影响因素及改进措施

电厂热工测量能够反映电厂热工工艺系统运行过程中各项设备的实时数据和工艺参数,同时也是保障电厂机组系统安全稳定运行的重要保障。在发电厂热工工艺系统运行过程中,采用热工测量技术对提高机组系统安全经济稳定稳定运行有着极其重要的作用。但是,在实际测量中,经常会出现测量误差,导致电厂各机组系统装置的安全稳定性能得不到保障。因此,本文就电厂热工测量的误差展开讨论,分析影响热工测量准确度的主要因素,并结合热工测量技术发展现状,采取切实有效的改进措施,以此提高电厂热工测量的准确性,减少误差现象的出现,进而提高电厂热工测量技术的实用性、精准性以及有效性,为电厂发电机组系统装置的安全稳定性能提供可靠保障。     

应用密度法测原油含水率

主要介绍用密度法对原油含水率进行快速测量和含水油田井站计量系统的工作原理、测量误差分析及含水原油液面自动控制原理、安全保护措施和系统运行工况,解决了原油产量的计量误差问题,提高了测量效率,减轻了测量工作强度。     

隧道贯通测量误差预计方案

此贯通为直线隧道贯通测量。主要分为洞外平面和高程控制测量,洞内平面和高程控制测量。洞外控制测量采用GPS布设GPS网进行控制,洞内用全站仪布设支导线进行控制;需要依据误差传播定律解决下列问题:a.地面平面控制测量误差引起贯通在重要方向上的误差:b.洞内平面控制测量引起贯通点重要方向上的误差;c.高程控制测量误差引起贯通点K在高程上的误差。     

浅析鹤煤六矿三水平辅助回风巷贯通误差预计

对六矿三水平辅助回风巷中水平误差和高程误差计算,所得的实际测量相对闭合差与《测量规程》中规定的相对闭合差进行比较,得出:贯通测量误差预计中,采用实际测量数据比用规程数据进行贯通测量误差预计更能提高测量误差预计精度。     

地铁工程项目中的施工测量与误差分析

地铁施工中,定位测量和贯通测量是两项基础性的测量工作,同时也关乎整个工程的安全和质量,因此明确施工控制测量中引起误差主要因素以及控制测量误差的积累成为地铁施工的重要环节。本文针对地面控制测量、竖井联系测量和区间隧道施工控制测量,进行了简单的误差分析和精度优化探讨。     

用实测数据分析GPS测量中的多路径误差

GPS测量与其他测量方法一样,在实际测量工作中同样也会受到各种因素的影响,导致其出现测量误差。由于GPS测量系统相对比较复杂,其误差的组成也相对比较复杂。多路径误差是其中最常见的一种误差形式,且其影响也相对比较严重,因此受到人们的高度重视。本文在实测数据的基础上对GPS测量工作中多路径误差进行全面分析,以供参考。     

电接点双金属温度计设定点误差测量结果的不确定度评定

电接点双金属温度计是附带电气接触装置的双金属温度计,具有自动控制和报警的功能。为了保证量值传递的准确性,通过搭建包括标准铂电阻温度计、标准恒温槽和信号通断测量电路在内的测量系统,对测量范围为(0～150)℃、分度值为2. 0℃的电接点双金属温度计的设定点误差进行校准,并完成测量结果的不确定度分析。结果显示,设定点误差测量结果的扩展不确定度U=0.4℃(k=2),满足检定规程JJG226-2001的要求。     

浅谈测量误差与不确定度的相关问题

在测量工作中。各项误差综合后的总极限误差被称之为测量的不用确定度。在目前社会发展中,很多的重要决策和工作方案的制定都是建立在科学合理的测量结果上。因此,在人们工作中将测量结果作为主要的决策的时候,非常关心测量结果的误差和可靠性。本文就测量误差与不确定度的几个问题进行分析,提出了相应的新观点。进而指出了适应测量不确定的应用要点。     

激光三角法测距的误差因素分析

在激光三角法测距中,被测物体表面特征、整个测量装置以及环境对测量精度都会产生一定的影响。文章从物面倾斜角度、被测物体表面曲率、被测物体表面颜色、被测物体表面粗糙度与光泽、CCD分辨率、光学系统相差、测量环境等方面对测量误差的产生进行了理论分析,重点从物面倾斜方面分析误差产生的原因,推算出光能质心光线的角位置、会聚光斑在CCD上的光能质心位置、测量误差大小的计算公式,在此基础上针对各种因素给出误差补偿方法。     

数字水准仪在测量过程中的误差来源及分析

数字水准仪在测量过程中由于受到各种因素的影响,测量的结果的误差也难以有效避免,因此如何最大限度的降低测量误差也是我们重点研究的内容,因此在数字水准仪测量时,我们需要对测量中产生误差的原因进行有效的分析,从而找出科学合理的解决办法。本文主要介绍了数字水准仪在测量过程中产生误差的来源,并且进行了针对性的分析说明。     

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.