R404A condensing under forced flow conditions inside smooth, microfin and cross-hatched horizontal tubes

Two-phase heat transfer coefficient characteristics of R404A condensing under forced flow conditions inside smooth, microfin and cross-hatched horizontal tubes are experimentally investigated. Experimental parameters include a lubricating polyol ester oil concentration varied from 0 to 4%. The test runs were done at average inlet saturated condensing temperatures of 40 °C. The inlet vapor was kept at saturation (quality=1.0). The mass fluxes were between 200 and 600 kg/m² s, and the heat fluxes were selected to obtain a quality of 0.0 at the outlet of the test section, varying from 5 to 45 kW/m². The heat transfer enhancement factor varied between 1.8 and 2.4 for both microfin and cross-hatched tubes. The larger values applied for larger mass fluxes for the cross-hatched tube and smaller mass fluxes for the microfin tube. Enhancement factors increased as oil concentration increased up to oil concentrations of 2%. For higher oil concentrations the enhancement decreased especially at high mass fluxes, the cross-hatched tube being less sensitive to oil contamination. Pressure drop in the test section increased by approximately 25% as the oil concentration increased from 0 to 4%. The results from the experiments are compared with those calculated from correlations reported in the literature. Moreover, modified correlations for the condensation heat transfer coefficient are proposed for practical applications.     

对经营者激励与控制的一些思考

着重从激励机制和内部控制等方面探讨出资者对经营者的管理问题。提出了采取有效激励措施，激发经营者的才能为公司增加财富，同时建立约束体系防止经营权侵犯所有权的一些思路。     

Reply to Seymour M. Lipset.

It is well known that sociological investigations, as a rule, lead to findings expressed in terms of correlations. Most data available on "student activism" fall into this category (it being illegal to conduct experiments with riots as the independent variable). The dangers involved in interpreting correlations as cause-and-effect relationships are equally well known, ideologically inclined investigators with strong social and political views being particularly ill suited for such a semioracular exercise. I suspect it was his ideological preconceptions that caused Seymour M. Lipset's (see record 1971-02248-001) self-admitted failing in 1964-65 to determine correct causes of organized student protest and violent confrontationist politics; and, having read his new article (Lipset, 1970) on the same subject, I fear the same hobgoblins were at work again. As on the previous occasion, Lipset again breathes life into the disconnected fragments of correlational bones and comes up with a living animal, different from last time but of the same species, again a creature of the same old cosmic plan that he carries in his left pocket. In general, his article seems more critical of the existing social order than of unruly students, and its author gives no practical advice regarding the kind of curative and preventive action that would relieve the current social crisis and check students' behavioral excesses. There is, I submit, another way of interpreting the phenomenon of student violence and social turmoil in general--a way that indicates both the form of the required remedial treatment and the feasibility of its immediate and direct application. This approach, in a way, makes use of Voltaire's insightful observation that "Enthusiasm is not always the companion of total ignorance, it is often that of erroneous information." Specifically, I suggest that the academic community is being heavily propagandized and that many students (and faculty members) have an appallingly inadequate historical understanding of the existing social, political, and economic situation. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

浅析拖欠工程款问题的原因及对策

文章针对建筑施工企业普遍存在的工程款拖欠问题,从社会信用体系、政府行为、建筑市场等角度深刻分析了形成的原因,提出了解决施工企业拖欠工程款问题的根治办法。     

The Poetics of the Island of Vessels

Since 2000, Neil Spiller has been engaged on a ‘long project’: a series of hundreds of drawings that through a potent mix of cyborgian fantasy and Surrealism, imbued with poetry and biotechnology, evoke a psycho-geographical island inhabited by an irascible alter ego, ‘The Professor’. Spiller seeks out in this work ‘an unusual and startling architecture’ that reveals a ‘loving, enigmatic and ragged beauty’.     

缸筒用高精度冷拔管内表面质量分析

通过对热轧管、冷拔管内表面缺陷的测量、分析,指出了影响缸筒用高精度冷拔管内表面质量的主要缺陷是麻点,以及减少麻点的具体措施和方法。     

一种内孔脉冲滚压工具的设计

孔的挤压加工是成批加工较小尺寸精密孔的一种简单和可靠的方法。运用脉冲滚压原理,设计制造了内孔挤压工具。经使用效果良好,被加工零件表面粗糙度、表面硬度和精度都有显著提高。     

Claiming participation – a comparative analysis of DIY urbanism in Denmark

The article discuss the conflicts, potentials and possible alliances of do-it-yourself (DIY) urbanism when it takes the form of spontaneous place appropriations, when it is performed as participatory urban design and when it is integrated strategically in planning. DIY urbanism and experimentation with participation are currently strong influential factors in Danish planning. The article explores the use of participatory DIY urban design in two cases: the relocation of beer drinkers in Enghave Square and the Carlsberg City development in Copenhagen, Denmark. Carlsberg City is the most thorough Danish example of how DIY urban design is employed as an investment and planning tool. It discusses the implications of DIY urbanism in terms of how it can be understood in the context of the struggles over ‘the right to the city’, how it applies different activist tactics for the appropriation of space, and how it is integrated in planning and the development logic.     

活塞环工艺技术综述

活塞环性能的优劣直接影响到内燃机的整体性能,随着现代内燃机的发展,对于活塞环提出了越来越高的要求。要实现活塞环的特性,加工技术就尤为重要,本文阐述了现代活塞环生产技术特点,并与传统加工方法进行对比,对它们的优缺点进行了分析,并体现了现代活塞环技术的发展趋势。     

低充氦浓度氦质谱检漏技术应用研究

为解决不允许抽真空和充压的密封装置的密封性能检测问题,开展了较低充氦浓度的氦质谱检漏模拟实验。实验采用通道型标准漏孔和模拟密封容器,在容器内的氦气浓度为0.5‰,1‰,3‰,5‰时分别实测了混合气体中氦气通过漏孔的漏率,基于混合气体以同种比分通过分子流漏孔的假设,不同浓度下测得的漏率结果与理论计算相比较;实验得出了在一定体积的空间内定点释放少量的氦气自由扩散至基本均匀分布所需时间。在实验的基础上,专门设计低充氦浓度检漏的标定装置,可降低因标准漏孔的氦浓度与检漏充氦浓度相差较大而引入检漏结果的不确定度。