Market imperfections in recycling markets: conceptual issues and empirical study of price volatility in plastics

The effectiveness of recycling depends upon efficient functioning of secondary material markets. This paper focus on the role that price volatility can play in slowing investment and market development. However, a statistical analysis of the relative volatility of secondary and primary material prices does not confirm the widely-held belief that relative price volatility is higher in secondary than in primary materials, at least at national levels.An econometric estimation of the determinants of plastic recovery volumes in Seattle contributes to the literature in four ways: the use of monthly (as opposed to annual) data; the use of local (as opposed to national) data; the use of an explanatory variable to reflect price volatility; and, the focus on plastics, which have not been examined previously. Some tentative conclusions can be made: the results generally support the principal hypothesis that price volatility has a negative effect on recovery of secondary materials; in addition, and consistent with previous studies, price elasticities are low and insignificant; and finally, policy factors are clearly important. The concluding section treats the economic and policy implications of market inefficiency in secondary material markets.     

含环向裂纹管道三通的塑性失效载荷

采用弹塑性有限元方法，系统分析了内压载荷下含环向裂纹管道三通的塑性失效载荷。探讨了管道三通塑性失效有限元分析中的建模技术，包括变形参量选取，网格收敛性研究等。给出了塑性失效载荷随裂纹尺寸变化的规律，以及不同裂纹位置(包括肩部和腹部)对三通塑性失效载荷的影响。最后根据有限元数值解建立了简单的塑性失效载荷估算式，研究结果可为下一步含缺陷管件完整性评定提供参考数据。     

塑料排水技术及其在环境岩土工程中的应用

介绍了常用塑料排水材料及其技术要求和性能;阐述了目前国内塑料排水技术在环境岩土工程中的应用状况,并就应用塑料排水技术解决岩土工程中的安全、生态和环境保护等问题提出了思路。笔者认为在岩土工程建设中,根据工程场地的地理、地质和生态环境条件,合理采用塑料排水材料,充分应用塑料排水技术,可以有效地保证工程设施的安全,实现环境岩土工程系统的相互促进和协调发展。文中同时介绍了塑料排水带真空和堆载预压地基固结渗透量的计算方法,可供参考。     

岩爆过程释放的能量分析

能量积累与耗散是岩爆机理研究的重要内容之一。以往的研究一般将岩爆过程释放的能量归结为隧道围岩的弹性应变能。分析表明，开挖状态下，围岩可以积蓄的宏观弹性应变能小于岩爆过程释放的总能量。根据理论物理学、结晶学及矿物学相关理论与岩爆特征，岩爆能量应属于破裂面两侧断裂晶体的应变能，并非围岩整体的应变能。岩爆破裂面断裂晶体的应变能是在裂纹到达的瞬间因晶体被拉伸到极限状态而达到最大值并高速释放的，因此，岩爆能量的积累过程是短暂的、瞬时的。岩爆过程释放的能量转化为表面能、动能及热能等形式，而动能是裂纹持续快速扩展的主要驱动力。     

A DECISION THEORY APPROACH TO EARTH DAM CLASSIFICATION1

ABSTRACT: The fact that dams have failed indicates that there is still a risk involved, in spite of the major effort to ensure reliability. In seeking ways to reduce the risk, all aspects of the design, construction, monitoring, inspection, and rehabilitation of earth dams should be examined. Because dam classification is a central element, ways of minimizing uncertainty associated with classification need to be considered. A Bayesian approach to classification has numerous advantages over existing methods of earth dam classification because it directly evaluates the effects of uncertainties. A framework for incorporating Bayesian decision theory into the classification process is presented.     

废塑料催化裂解制燃料油

用自制的L不列催化剂对聚乙烯，聚丙烯，聚苯乙烯及其按不同比例混合的3种废塑料催化裂解制燃料油进行了研究。试验结果表明：混合废塑料料经过催化解制得的90^#汽油和0^#柴油的质量均达到国家标准。油品品质的好坏主要由废塑料的种类，催化剂和催化改质温度3个因素决定。     

ABS工程塑料挤出机烟气净化工艺研究

采用热解釜热解ABS工程塑料碎块所产生的含有毒物质的烟气温度为160-180℃，通过热交换器将烟气温度降至40℃后，烟气进入吸收塔，用特配的ABS吸收液净化烟气中的苯乙烯、丙烯腈等有毒气体，吸收有毒气体的ABS吸收废液经活性白土再生后返回吸收塔继续使用。整个系统无新污染物产生和外排。净化效率和再生效率均达95％以上，净化后的排气可达到国家标准GB16297-96的要求。     

等离子体技术在废旧塑料资源化中的应用

叙述了废旧塑料回收利用对环境的影响，介绍了废旧塑料资源化几种重要的方法及资源化中存在的问题，分析了等离子体技术在废旧塑料资源化中的特点及存在的问题，并提出了解决方法。     

Development aid: The moral obligation to innovation

The prominent, though not exclusive, role of basic needs strategies to attain ethically acceptable development goals raises the question of the ability of development agencies to find and employ basic needs strategies. The obligation to prevent severe human suffering leads to the obligation to employ basic needs strategies to attain basic needs goals. The history of failure by development agencies in finding and employing basic needs tools leads to a further obligation to cultivate bureaucratic environments which foster profound innovation. This requires not only new tools but also new bureaucratic behaviour. An understandable obstacle to simultaneously technological and bureaucratic innovation lies in the tension between responsible behaviour and behaviour promoting fundamental change. Since this tension is based on the unpredictability of creative change, a series of axioms and corollaries which reduce the unpredictability is given. They include: (1) an obligation to seek innovation; (2) a clear statement of basic needs goals and intent to use some basic needs tools; (3) increase in effective knowledge of the poor and their survival strategies; (4) bureaucratic learning flexibility; (5) participatory development and allied emphasis on sustainable resource technologies. The embodiment of these in the learning process approach is illustrated.