Continuous formation of slurry ice by cooling water–oil emulsion in a tube

Water-silicone oil emulsion with an additive, (C₂H₅O)₃SiC₃H₆NH₂, was examined as a heat storage material. A spiral tube used as a heat exchanger was immersed in a low temperature bath and the emulsion was circulated in the tube to make ice continuously. Ice was separated from the ice–liquid suspension in an outlet tank. The amount of formed ice, the temperatures of the inlet and the outlet of the heat exchanger, and the temperatures in the tube wall were measured and the overall heat transfer coefficient and the heat flux through the tube were calculated. Experiments were carried out, varying the flow rate, the temperature of cooling brine, and the thickness of tube wall. The condition under which slurry ice was formed continuously without adhesion of ice to the cooling wall was clarified. Though decrease in the thermal resistance of the tube increased the rate of ice formation or raised the brine temperature, it narrowed the range of the flow rate and of the brine temperature in which slurry ice was formed continuously.     

固液相变蓄能的数学模型和自然对流换热系数的实验研究

引入自然对流换热系数 ,将固液蓄能数学模型简化为仅用能量方程加以描述。并通过实验测得相变过程的实际温度场 ,证明了自然对流固液相变换热的影响不可忽略 ,验证了固液相变界面移动速率随自然对流换热系数的增大而增大的定性关系     

云南省水环境状况及问题分析

根据2000年云南省主要河流水质监测评价结果，全省评价河段总长9280km中，水质为Ⅰ－Ⅲ类的河长占76．3％，总体上，云南省内各大水系水质良好，但水污染总体上正在加重，从1985－2000年，Ⅰ类河长年均减少2．3％，V类河长年均增长0．6％，废污水直接排入江河是引起污染的重要原因。水环境问题已成为社会经济可持续发展的关键问题，要切实加强水资源的保护，科学地开发利用水土资源，为了有效地改善水环境的质量，污染控制应从源头开始并采取综合治理措施。     

黑河干流中游地区耗水量变化的历史分析

黑河流域水资源极其匮乏，加之地区上的配置不均衡和中游地区水土资源的过度开发，导致黑河下游出现了严重的生态环境问题，已影响到我国北方广大地区生态环境质量，受到国家的高度重视和全社会的广泛关注。黑河水资源开发利用主要集中在中游地区，该区是全国重要的商品粮、蔬菜和经济作物生产基地之一，耗水量占流域耗水量的85％以上，是黑河的主要耗水区和径流利用区。利用黑河上游控制站莺落峡站和中游控制站正义峡站水文资料，分析了黑河中游耗水量的变化，结果表明：20世纪80年代以前黑河中游耗水量在4．4亿m^3左右，比较稳定；进入20世纪80年代以后，耗水量明显增加，80年代耗水量比70年代以前增加了1．97亿－2.49亿m^3;90年代耗水量又比80年代增加了1.64亿m^3左右；80年代以来流域耗水量呈明显增加的趋势，这是以人类活动影响为主的结果。     

储层横向相变对剩余油分布的影响

处在构造边部、低部位的商５－５井，在改注水井排液中发现不含水的高产这种非常规现象，由此引起对地质因素的分析。浅湖相沉积的主体是滩砂微相，它可细分为“滩脊”和“滩侧”，其中“滩脊”砂体的泥质含量低，孔隙度、渗透率都较高，而“滩侧”则泥质含量高，物性差。在从“滩脊”砂体向“滩侧”过渡时，极易形成类似于砂体尖灭的岩性封堵，造成剩余油富集，而“滩脊”不一定就在构造的高部位。陆相沉积的砂体非均质性很强，孔隙度和渗透率在横向上的变化很大，高部位的油层水淹，低部位的油层不一定就高含水，这是因为砂体横向上的非均质性，使同一时间单元沉积的砂体很可能不连通。基于这些分析，地质工作者不妨运用沉积微相的原理在构造的低部位或边部寻找剩余油富集区，商５－５井的现实给了我们很好的启示。     

Danish and Norwegian wind industry: The relationship between policy instruments, innovation and diffusion

This article compares the role of policy instruments in stimulating long-term technological change in Danish and Norwegian wind industry. It concludes that although predictability has periodically been low, Denmark's broad portfolio of policies and measures has been well adapted to the different stages in the development of its wind industry. This has contributed to a high degree of innovation, successful establishment in niche markets, high degree of diffusion and establishment of domestic and international mass markets, and—in recent years—an increasingly successful replacement of senescent technology with new. The motivation of Norway's wind energy policies and measures—at least up until the late 1990s—has been to increase power supply rather than to stimulate industrial development and technological change. Policies and measures have been weaker than in Denmark; have been less stable over time; and stimulated the demand side much less. They have not sufficiently covered the wind industry's perceived needs on different stages in the development of new technology, and have not sufficiently stimulated continuous improvement, learning and new product development (dynamic efficiency) in industry. This has been part of the reason why there has been only a limited extent of innovation and diffusion of wind technology in Norway.     

Preparation and characterization of polyurethane microcapsules containing n‐octadecane with styrene‐maleic anhydride as a surfactant by interfacial polycondensation

A series of polyurethane microcapsules containing a phase change material (PCM) of n‐octadecane was successfully synthesized by an interfacial polymerization in aqueous styrene‐maleic anhydride (SMA) dispersion with diethylene triamine (DETA) as a chain extender reacting with toluene‐2,4‐diisocyanate (TDI). The average diameter of microPCMs is in the range of 5–10 μm under the stirring speed of 3000–4000 rpm. Optical and SEM morphologies of microPCMs had ensured that the shell was regularly fabricated with the influence of SMA. FTIR results confirmed that the shell material was polyurethane and the SMA chains associated on core material reacted with TDI forming a part of shell material. The shell thickness was decreasing in the range of 0.31–0.55 μm with the molar ratio of DETA/TDI from 0.84 to 1.35 and the weight of core material increasing from 40 to 80% (wt %). By controlling the weight ratio of PCM as 40, 50, 60, 70, and 80% in microPCMs, it was found using DSC that the T_m and T_c of microPCMs were in the range of 29.8–31.0^oC and 21.1–22.0°C and an obvious phase change had been achieved nearly the same temperature range of that of PCM. The results from release curves of microPCM samples prepared by 1.4, 1.7, and 2.0 g of SMA indicated the release properties were affected by the amount of the dispersant, which attributed to the emulsion effect and shell polymerization structure. The above results suggest that the shell structure of microPCMs can be controlled and the properties of microPCMs determined by shell will perform proper practical usage. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 4996–5006, 2006     

Synthesis of Nearly Monodisperse Iron Oxide and Oxyhydroxide Nanocrystals

Uniform magnetite, hematite, and goethite nanocrystals were prepared through an attractive method based on an oleic acid/alcohol/water system. By adjusting the synthetic parameters (base concentration, alcohol content, categories of alcohols, etc.), the controlled synthesis of uniform magnetite, hematite, and goethite nanocrystals can be easily achieved. Detailed investigations on the effect of the experimental parameters on the morphology of the final products and the phase transitions among the magnetite, hematite, and goethite phases were carried out. Finally, a method of doping other metal ions into magnetite was developed and the magnetic properties of magnetite doped with different metal elements were studied.     

The 'Conceptual Change In Science' project

Abstract This paper outlines the work of the Conceptual Change in Science project, funded as part of the ESRC InTER programme. The aims of this research project are to clarify and describe the process of change in learners' conceptual understandings of natural phenomena. The domain of reasoning selected for study is that of mechanics. Computer software which may be useful in exploring and developing pupils' reasoning and promoting conceptual change in this domain is being developed and evaluated. The group that is carrying out the research is based at the Universities of Leeds, Glasgow and the Open University.     

基于过程能力指数的刀具寿命研究

利用Glejser检验方法拟舍出刀具磨损过程残差模型，在此基础上，计算换刀时刻的过程能力指数，并且根据企业所要求的最低过程能力指数，计算刀具的质量寿命，提出将刀具的切削寿命和质量寿命结合起来进行换刀决策的方法。