快淬贮氢合金的活化性能与寿命

主要讨论了快淬钛基合金具有良好活化性能及较差循环寿命的机理。研究结果表明:快淬钛基合金电极浸泡在碱液中,合金元素V、Zr、Ti、Mn、Ni以不同速度溶解,其中Ni的溶解速度最慢,使合金电极表面富Ni。富Ni电极表面具有良好的动力学性能,快淬钛基贮氢合金的放电容量急剧衰退与损失大量可吸氢的V、Zr元素密切相关。     

低温冷冻干燥装置的研制

冷冻干燥过程的研究对实验室用小型冷冻干燥装置提出了新的性能要求。笔者设计并制作了一台低温冷冻干燥装置 ,首次应用新型的自动复叠循环作其制冷系统。该装置最低制冷温度低于 - 80℃ ,并且能对温度、真空度以及制品质量进行准确地测量和控制 ,可用于多种制品冷冻干燥过程的研究和优化     

Life cycle environmental performance and improvement of a yogurt product delivery system

A life cycle assessment was conducted to evaluate the environmental performance of the yogurt product delivery system used by Stonyfield Farm. A life cycle model was developed which included material production, manufacturing and disposition for primary and secondary packaging, as well as the related transportation links between these stages and filling, retail and the point of consumption. Product delivery systems (PDS) that utilized 4, 6, 8 and 32 oz polypropylene (PP) cups and 2 oz linear low‐density polyethylene (LLDPE) tubes were analysed. Ten strategies for improving the environmental performance of these systems were proposed and their impacts on the total life cycle burden were analysed. The life cycle energy consumption for the 2, 4, 6, 8 and 32 oz containers was 4050, 4670, 5230, 4390 and 3620 MJ/1000 lb yogurt delivered to market, respectively. Material production of the primary packaging accounted for 58% of the life cycle energy, while Distribution 3 (yogurt delivery to distributors/retailers) alone accounted for one‐third of the life cycle total energy. The life cycle solid waste profile showed that as the container size decreased, the solid waste burden increased, from 27.3 kg (32 oz) to 42.8 kg (6 oz) per 1000 lb yogurt delivered to market. This relationship was even more pronounced for the 4 oz (47.5 kg) and 2 oz (56.2 kg) product delivery systems. The greatest potential improvements in the environmental performance of the PDS are achievable through redesigning the primary packaging and using alternative manufacturing techniques for the yogurt cups. Shifting from injection moulding to thermoforming of 32 oz container reduces the life cycle energy and solid waste by 18.6% and 19.5%, respectively, primarily due to light‐weighting. Elimination of lids for 6 oz and 8 oz containers provided similar benefits. Consumers purchasing yogurt in 32 oz instead of 6 oz containers can save 14.5% of the life cycle energy and decrease solid waste by 27.2%. Copyright © 2004 John Wiley & Sons, Ltd.     

Mass recovery adsorption refrigeration cycle—improving cooling capacity

The study investigates the performance of two-bed, silica gel-water adsorption refrigeration cycle with mass recovery process. The cycle with mass recovery can be driven by the relatively low temperature heat source. In an adsorption refrigeration cycle, the pressures in adsorber and desorber are different. The chiller with mass recovery process utilizes the pressure difference to enhance the refrigerant mass circulation. Cooling capacity and coefficient of performance (COP) were calculated by cycle simulation computer program to analyze the influences of operating conditions. The mass recovery cycle was compared with conventional cycle such as the single stage adsorption cycle in terms of cooling capacity and COP. The results show that the cooling capacity of mass recovery cycle is superior to that of conventional cycle and the mass recovery process is more effective for low regenerating temperature.     

Flash gas bypass for improving the performance of transcritical R744 systems that use microchannel evaporators

The performance of transcritical R744 systems with direct expansion (DX) can be significantly improved by implementing a Flash Gas Bypass (FGB). The idea behind the concept is to bypass refrigerant vapor, created during the isenthalpic expansion process, around the evaporator. By feeding the evaporator with liquid refrigerant, pressure drop is reduced and refrigerant distribution is improved. With R744 as the working fluid, increased refrigerant-side heat transfer coefficients are expected as well. In addition, the FGB concept proves to be beneficial in terms of system design, in particular for combined air-conditioning and heat pumping applications. An experimental comparison to a conventional DX-system reveals that FGB increases the cooling capacity and COP at the same time by up to 9 and 7%, respectively. Even larger improvements are possible in case a variable speed compressor is utilized to match the performance of the conventional DX-system. A simulation model helps to separate the individual improvement mechanisms. It was found that the reduction of refrigerant-side pressure drop is the dominant improvement mechanism of FGB.     

终身教育体系下成人教育的改革和发展策略

探讨了成人教育作为传统学校教育向终身教育发展的一种新型教育制度,应以终身教育理念为导向进行改革和发展,并提出了新的发展目标和策略.     

低热值煤气燃气轮机联合循环发电在钢铁厂的应用

燃气轮机联合循环发电效率比常规电厂高10个百分点左右。适合钢铁厂低热值煤气燃气轮机有单筒燃烧器和多筒燃烧器二种类型。容量应按钢铁厂富余煤气量呈正态分布的规律计算确定。文章还介绍了轴制．煤气预处理、电网联网等特殊问题。50MW左右的机组已有国产化的实例。     

Serviceability of Materials in the Tropics

With increasing complexity in the building construction trend and the advancement of building material technology, more building materials and substitutes have evolved and been adopted for use to function together in a building that is supposed to maintain its technical performance during its intended working life. Condition surveys of 450 buildings, face-to-face interviews, and workshops were conducted with industry specialists, to examine the behavior of materials used in facades and wet areas in tropical climates and their estimated costs of maintenance. This paper presents an indicative computational method for the durability of building materials for fa?ades and wet areas in the tropics. Total operations and maintenance costs of the identified materials are also included to provide suggestive maintenance expenditure over the materials’ service life. Natural stone was preferred as a more durable fa?ade material while ceramic and homogeneous tiles proved more economical for wet areas.     

Axial offset control of PWR nuclear reactor core using intelligent techniques

Improved load following capability is one of the main technical performances of advanced PWR (APWR). Controlling the nuclear reactor core during load following operation encounters some difficulties. These difficulties mainly arise from nuclear reactor core limitations in local power peaking, while the core is subject to large and sharp variation of local power density during transients. Axial offset (AO) is the parameter usually used to represent of core power peaking, in form of a practical parameter. This paper, proposes a new intelligent approach to AO control of PWR nuclear reactors core during load following operation. This method uses a neural network model of the core to predict the dynamic behavior of the core and a fuzzy critic based on the operator knowledge and experience for the purpose of decision-making during load following operations. Simulation results show that this method can use optimum control rod groups maneuver with variable overlapping and may improve the reactor load following capability.     

某星载大口径天线子系统的力学仿真分析

星载天线在发射及在轨阶段将面临严酷的力学环境,要求具有极高的可靠性。为了验证其刚度和强度,缩短研发周期,文中采用NX Nastran软件建立了某星载大口径天线子系统的力学仿真模型;为了验证仿真的有效性,进行了该天线子系统的模态测试,经对比发现两者数据一致性较好;基于建立的有限元模型,分析了该天线子系统在正弦振动和热循环环境工况下的结构响应和受力情况,得到了相应的加速度、位移和应力云图。结果表明,该天线子系统的结构刚强度均满足星载环境要求。该仿真分析对星载天线子系统的结构设计具有重要的指导意义。