位于射流喷射区的高浓度悬浮固粒扰动特性

利用双流体模型和扰动速度势理论，推得位于射流喷射区高浓度悬浮固粒的固气扰动复速度比值方程，通过数值计算，得到了不同雷诺数及固粒属性下固气扰动复速度比值曲线，分析该曲线，得到了关于流场雷诺数及固粒等效斯托克斯数对固粒跟随气流的扰动性能影响的结论，这些结论是在计入气流粘性的条件下得到的，对于两相射流发展的认识和工程实际中实施对两相射流场的人工控制有重要意义。     

基于数值模拟的流线收敛型喷嘴内流场动力特性研究

本文以后混合磨料射流所使用的单射流侧进磨料流线收敛型喷嘴为研究对象,利用流体仿真软件对喷嘴内部的两相流流场情况进行了数值模拟,从而得出了轴平面上压强和湍流强度分布云图,进而分析了喷嘴内部的动力特性。研究结果表明,流线收敛型喷嘴内部动力特性过渡十分平缓,流体冲击较小,喷嘴的使用寿命较高。     

井底脱气条件下采液指数的预测方法研究

流压远低于饱和压力时,在油井附近形成脱气圈,渗流条件发生变化,地层内两相流变为油气水三相流。在原油脱气情况下,油相相对渗透率不仅是含水饱和度的函数,也是含气饱和度的函数,因此用油水两相相渗曲线计算的采液指数存在较大误差。本文提出了用油层气油比修正采液指数,计算不同含水条件下采液指数的方法。     

饱和土体中圆柱体对弹性波的散射

考虑土颗粒与孔隙流体的压缩以及孔隙流体与土骨架之间的粘性耦合作用,采用修正的Biot模型,研究了入射平面P1波在饱和土中饱和圆柱体上的散射问题,得到了散射和折射波场势函数的幅值方程,并对背向散射形函数随无量纲频率的变化曲线以及不同无量纲频率的径向位移沿周向的分布曲线进行了数值模拟。     

隧道弃渣场边坡稳定性数值模拟分析

正为了准确评估新建长昆客运专线长沙至玉屏段2号隧道1号斜井弃渣场边坡稳定性,防止其产生滑坡造成生命财产巨大损失,采用Geo Studio软件建立数值模型,确定模型参数和边界条件,计算分析不同工况、不同方法条件下弃渣场边坡的稳定性。结果表明:降雨入渗对弃渣场边坡稳定性影响很小;在不同工况下,弃渣场边坡安全系数均大于所规定的边坡安全系数控制标     

关于扭力冲击器内分离单元的流场CFD模拟分析

由于扭力冲击器的各个结构之间采用的是间隙配合,且动力冲击组中各个零件都处于高速运转的状态,因此对泥浆有一定的要求。为了使设备不被泥浆中的固相颗粒卡死,以及减少颗粒对运动部件的冲击,就需要一个净化单元对泥浆中的固体颗粒进行分,因此将对其固液分离作出分析研究。简要地介绍了固-液分离器的工作原理。对分离器进行几何建模,并对进行网格划分和边界条件的定义。并用计算流体力学CFD数值方法,并采用雷诺应力RSM[1-2]模型对分离器的流场进行数值模拟。对固-液两相流进行了研究,得出分离器内压力场和各相体积分数分布的情况等。分析泥浆中固相颗粒直径和旋流器结构参数对分离效率的影响。为进一步探究旋流特性参数对分离效率的影响和旋流器的结构优化提供了参考。     

双稳射流元件压力特性的研究

用理论分析和数值模拟和实验研究的方法，分析了双稳射流元件内流体流动的状况，计算了压力在双稳内的传播和压力波射流的控制。计算结果显示，射流由双稳元件内的压力控制，且压力呈现周期性变化。控制压力会随入口压力的变化而不同。     

利用三次样条插值函数模拟机翼下曲线轮廓

用梯形积分法和希普森法模拟机翼下曲线的轮廓,虽然计算比较简单、稳定性好,但精度比较差。利用样条插值,既保证了计算的稳定性,又提高了计算的精度。故给出利用三次样条插值构造机翼曲线的函数和计算步骤,并用Matlab软件编写三次样条函数的程序,绘出机翼轮廓的曲线图形。     

不同转速下搅拌器混合效果数值模拟

搅拌罐内液-固两相混合搅拌是为了使固相颗粒能够离开底部比较均匀的悬浮于流场内部,从而促进液相与固相之间的接触,最终达到均匀混合的目的。通过对罐内流场进行建模后,把流场网格模型导入FLUENT软件中进行数值模拟仿真,探究流场内流体的运动规律与混合情况,针对转速对搅拌罐内混合效果的影响进行数值计算,最终使水泥颗粒能在搅拌罐内均匀分布。     

基于Bean-Rodbell模型的一级相变材料的磁热效应分析

引入基于分子场假设的Bean-Rodbell模型,通过求解系统的吉布斯自由能极小值,获得磁状态方程,进而得到系统的磁热曲线和磁熵。利用不同磁场下的磁熵曲线计算得到系统的等温磁熵变。     

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.