Pseudo bond graphs of circulating Fluids with application to solar Heating design

Two different bond-graph schemes for the modeling of circulating fluids are discussed and compared. The first uses a heuristic approach wherein the flow path is broken into segments. Each segment has separate hydraulic and thermal submodels which are linked with active bonds. The model is general enough to handle natural convective flows, heat storage, conduction, forced convective heat transfer and heat energy sources. The second method, applicable to pumped flows, uses a modal analysis approach to derive state equations for the modal temperatures, the time varying coefficients of the spatially varying mode shapes in a separation of variables solution for the temperature partial differential equation. Two examples are worked to illustrate the models. Numerical simulation results are presented using the first method and a simple analytic solution given to illustrate the second.     

秦始皇兵马俑博物馆室内含硫颗粒物的SEM-EDX研究

本文对秦始皇兵马俑博物馆室内采集的长短期降尘、大气悬浮颗粒物和彩绘漆层进行了SEM-EDX研究，在大气悬浮颗粒、短期和长期降尘中，含硫颗粒的粒径分别为0.9～22.8μm、1.0～29.0μm和1.2～37.7μm，多为石膏与粘土或石英以内部混合的状态存在。降尘中的附着型絮状硫酸钙多于大气悬浮颗粒物中，显示降尘和大气中的二氧化硫发生了累进的化学反应。彩绘漆层表面的坑和裂隙附近观察到原位生长的硫酸钙晶体，显示漆层材料或降尘颗粒物与大气二氧化硫之间的酸化学反应，可能是彩绘漆层表面受侵蚀形成微小坑和裂隙的原因之一。     

Weak Ties in Networked Communities

Communities with high levels of social capital are likely to have a higher quality of life than communities with low social capital. This is due to the greater ability of such communities to organize and mobilize effectively for collective action because they have high levels of social trust, dense social networks, and well-established norms of mutuality (the major features of social capital). Communities with “bridging” social capital (weak ties across groups) as well as “bonding” social capital (strong ties within groups) are the most effective in organizing for collective action. People who belong to multiple groups act as bridging ties. When people with bridging ties use communication media, such as the Internet, they enhance their capability to educate community members and to organize, as needed, for collective action. This article summarizes evidence from stratified household survey data in Blacksburg, VA, showing that people with weak (bridging) ties across groups have higher levels of community involvement, civic interest, and collective efficacy than people without bridging ties among groups. Moreover, heavy Internet users with bridging ties have higher social engagement, use the Internet for social purposes, and have been attending more local meetings and events since going online than heavy Internet users with no bridging ties. These findings may suggest that the Internet—in the hands of bridging individuals-is a tool for enhancing social relations and information exchange, and for increasing face-to-face interaction, all of which help to build both bonding and bridging social capital in communities.     

N-acetyl-β-D-glucosaminidase,alanine aminopeptidase and protein: Creatinine ratio as early indicators of diabetic microangiopathy

The urinary excretion patterns of N-acetyl-β-D-glucosaminidase (NAG), alanine aminopeptidase (AAP) and protein/creatinine ratio (UP/UCR) were studied in 133 diabetic subjects under treatment, 7 patients with established diabetic nephropathy (DN) and 79 carefully selected (age-matched) healthy subjects. NAG, AAP and UP/UCR were highly elevated in DN, while in diabetics urinary NAG levels correlated well with the degree of long-term metabolic control indicated by glycosylated hemoglobin (GHB or Hba1). Both AAP and UP/UCR were found to be more sensitive than NAG, but less specific. Urinary NAG and AAP assays thus offer simple, sensitive and non-invasive techniques for prognostic indication of the onset of microangiopathic changes in long-term diabetic subjects.     

基于SSM分折的科研评价系统探讨

科技评价体系是一个复杂的,多目标评价体系。当今科技评价已逐渐从强调科研产出,转向同时关注资源的使用效率,注重科技创新能力的提升和对国民经济发展的贡献。如何建立一个客观、公正、健全、规范的,且具备可操作性的科学评价体系引起了政府和科技界的广泛关注。本文以SSM系统分析为基础,从3E出发探讨了评价指标体系的构建和评价系统的设计。基于系统分析基础上形成的指标体系,既考虑了直接的产出,又分析了内部运行机制,形成的指标体系相对更全面、完整,在此基础上针对具体评价内容选择适宜的评价方法,可定量或定性,软硬结合,具有透明性和延展性,同时易与决策管理部门交流。     

Editorial

Knowledge Management Research & Practice -     

Editorial

Knowledge Management Research & Practice -     

Left-handed materials in magnetized metallic magnetic thin films

INTRODUCTION Veselago (1968) showed that if both the permit- tivity ε and the magnetic permeability μ of a material are negative, the propagation direction of an elec- tromagnetic (EM) wave will be opposite to its energy flow direction. Such media are called left-handed materials (LHMs) since the electric field E, magnetic field H, and wave vector k in these media form a left-hand triplet of vectors, instead of a right-hand triplet observed in conventional materials. For a long time, …     

The assessment and prevention of answer copying on undergraduate multiple-choice examinations

Multiple-choice examination answer copying was indexed by a comparison of the numbers of items answered incorrectly, and in the same way, as adjacent and distant classmates. In Experiment I, which involved a regular university examination, significant copying did occur, did not differ from front to rear of the lecture hall, and appeared primarily among individuals seated next to one another. Copying was not related to the order in which the examinations were returned. Number correct was related to turn-in order in a U-shaped fashion. No significant copying appeared in a second experiment, where test performance did not contribute to course grade.