On the numerical implementation of variational arbitrary Lagrangian–Eulerian (VALE) formulations

This paper is concerned with the implementation of variational arbitrary Lagrangian–Eulerian formulations, also known as variational r‐adaption methods. These methods seek to minimize the energy function with respect to the finite‐element mesh over the reference configuration of the body. We propose a solution strategy based on a viscous regularization of the configurational forces. This procedure eliminates the ill‐posedness of the problem without changing its solutions, i.e. the minimizers of the regularized problems are also minimizers of the original functional. We also develop strategies for optimizing the triangulation, or mesh connectivity, and for allowing nodes to migrate in and out of the boundary of the domain. Selected numerical examples demonstrate the robustness of the solution procedures and their ability to produce highly anisotropic mesh refinement in regions of high energy density. Copyright © 2006 John Wiley & Sons, Ltd.     

Liquid film and droplet flow behaviour and heat transfer characteristics of herringbone microfin tubes

Cross-sectional liquid flow rate distribution of vapour liquid two phase flow of R123 in different herringbone microfin tubes has been measured. Droplet and liquid film flow rates are calculated with the measured data and assumptions for droplet distribution and slip ratio. Heat transfer coefficients of evaporation and condensation in herringbone microfin tubes have been measured using R22. Heat transfer enhancement mechanism by the herringbone microfins is discussed by using the measured data and numerically obtained cross-sectional flow field of a single phase flow. Flow rate of thin liquid film flowing on tube sides is affected by the helix angle and fin height. Larger helix angle and higher fin give thinner film. Liquid film flow rates in tube top and bottom are higher than tube sides. Droplet flow rate is increased with increase of helix angle and fin height, although the effect of fin height is not as pronounced as helix angle. Droplet radial mass velocity to tube side walls is increased with helix angle.     

Importance of Third Virial Coefficients for Representing the Gaseous Phase Based on Measuring PVT-Properties of 1,1,1-Trifluoroethane (R143a)

For a reliable derivation of the thermodynamic properties in the gaseous phase from thermodynamic equations of state, it has been pointed out that third virial coefficients significantly affect calculations of heat capacities. Among existing equations of state including internationally accepted equations, there is a large discrepancy, sometimes more than 5%, in calculated heat-capacity values near saturation. Two different approaches have been conducted in addressing this problem. One is for providing the third virial coefficient from intermolecular-potential models based on speed-of-sound measurements with a spherical resonator, and another is for confirming the effect of the third virial coefficient on density values near saturation by measuring the density precisely with a magnetic suspension densimeter. This report is focused on the latter case, i.e., precise measurements of density for 1,1,1-trifluoroethane, R143a, near saturation and some important evidence for the necessity of considering third virial coefficients for calculating reliable thermodynamic properties in the gaseous phase.Paper presented at the Seventh Asian Thermophysical Properties Conference, August 23–28, 2004, Hefei and Huangshan, Anhui, P. R. China.     

基于LTCC多层基板技术的宽带T/R组件设计

介绍了一种基于低温共烧陶瓷(LTCC)多层基板工艺的宽带发射/接收(T/R)组件的设计,详细论述了组件的电路布局和装配工艺,给出了具体的测试数据。T/R组件的体积为65mm×29mm×9mm,连续波输出功率大于25W,均方根移相误差小于3°,已达到工程应用要求。     

面向数字化校园的异构数据集成技术研究

分析了数字化校园建设过程中异构数据集成的重要性,详细介绍了异构数据库系统的特征和异构数据集成的几种方法,研究XML在异构数据集成方面的应用。在此基础上,设计出基于XML的异构数据集成模型,来解决数字化校园建设中的"信息孤岛"问题。     

CPK认证研究及在高校数字化校园系统中的应用

由于校园网访问方式多样、用户群体庞大、网络行为突发性高、各种信息安全事故和病毒等频繁出现,严重影响了校园网络的正常运行,而认证系统则是高校数字化校园系统中的难点。论文对数字化校园系统中认证技术的现状进行了研究,并深入分析了最新认证技术CPK认证,将其成功实现并实施于高校数字化校园系统中。     

基于校园门户平台图书馆管理系统的集成研究

图书馆管理系统的集成工作是当前数字化校园建设工作中的重点,基于门户平台的图书馆管理系统的集成包括统一身份认证集成、共享数据集成及信息门户集成。这里详细介绍此三大领域的集成目标与集成方式,并为校内远程数字资源访问功能的实现提供了切实可行的技术解决方案,使居住在校外的教职工通过统一身份认证方式成功访问校内远程数字资源,为其他院校从事该领域研究工作提供一定的借鉴。     

有源阵列天线的发展及应用

介绍了有源阵列天线的发展概况、组成结构及技术特点,并对比其与无源阵列天线的优缺点,讨论了有源阵列天线的应用及发展前景。     

基于6R的绿色服装生产决策及其应用

绿色服装的生产决策包括新产品投资方案决策、设计方案决策、工艺规划决策、物料消耗决策、作业调度决策以及废旧产品回收决策.文章首先介绍了上述决策过程,然后提出了一种基于BP算法的神经网络决策方法,实现了决策中的公平性和合理性.同时,又将6R模型引入到决策中,根据6R中各变量的排序作出最优决策.     

A highly stable whole‐cell biocatalyst for the enantioselective synthesis of optically active alpha‐hydroxy acids

BACKGROUND: Biocatalysts have gained increasing attention because of their inherent advantages over chemical catalysts. However, the poor operational stability has always prevented their broad application. In this study, (R)‐mandelic acid was chosen as a model compound of alpha‐hydroxy acids. The objective was to obtain a new biocatalyst with desired operational stability for the preparation of (R)‐mandelic acid as well as other optically pure alpha‐hydroxy acids of pharmaceutical importance. RESULTS: Using a two‐step screening strategy, Saccharomyces ellipsoideus GIM2.105 was selected as an effective biocatalyst with high enantioselectivity and remarkable operational stability. After 20 cycles of reuse, whole cells of S. ellipsoideus GIM2.105 maintained its activity, and no obvious decrease in conversion or enantiomeric excess (ee) was observed. Furthermore, effects of various reaction parameters, including pH, temperature, co‐substrate (type, concentration), substrate concentration and reaction time, on the bioreduction were studied. Under optimal conditions, (R)‐mandelic acid and four substituted aromatic (R)‐alpha‐hydroxy acids were prepared in high ee (95–>99%) and good conversion (>90%). CONCLUSION: The high enantioselectivity, remarkable operational stability and mild reaction conditions showed S. ellipsoideus GIM2.105 to be an economical biocatalyst with great industrial application potential for the production of optically active alpha‐hydroxy acids. Copyright © 2009 Society of Chemical Industry