Competing hypotheses analyses of the associations between group task conflict and group relationship conflict

Although previous research have reported strong and positive intercorrelations between group task conflict and group relationship conflict, several different theoretical rationales exist for the positive link and the empirical literature remains equivocal. To clarify the causal linkage between the two types of conflict, we derived seven models specifying how group task and relationship conflict can be related to each other, including some rival explanations. We tested the competing models using a longitudinal panel design, with data collected from 74 project teams comprising a total of 388 students. The results indicated that relationship conflict led to an increased subsequent task conflict through negative group affect. Task conflict, however, predicted a subsequent relationship conflict under a specific context, that is, groups that had lower levels of trust among the members. Copyright © 2010 John Wiley & Sons, Ltd.     

Effect of environmental parameters on the degradability of polymer films in laboratory-scale composting reactors

Previous research in our laboratory reported a convenient laboratory-scale composting test method to study the weight loss of polymer films in aerobic thermophilic (53°C) reactors maintained at a 60% moisture content. The laboratory-scale compost reactors contained the following synthetic compost mixture (percentage on dry-weight basis): tree leaves (45.0), shredded paper (16.5), food (6.7), meat (5.8), cow manure (17.5), sawdust (1.9), aluminum and steel shavings (2.4), glass beads (1.3), urea (1.9), and a compost seed (1.0) which is designated Mix-1 in this work. To simplify the laboratory-scale compost weight loss test method and better understand how compost mixture compositions and environmental parameters affect the rate of plastic degradation, a systematic variation of the synthetic mixture composition as well as the moisture content was carried out. Cellulose acetate (CA) with a degree of substitution (DS) value of 1.7 and cellophane films were chosen as test polymer substrates for this work. The extent of CA DS-1.7 and cellophane weight loss as a function of the exposure time remained unchanged when the metal and glass components of the mixture were excluded in Mix-2. Further study showed that large variations in the mixture composition such as the replacement of tree leaves, food, meat, and sawdust with steam-exploded wood and alfalfa (forming Mix-C) could be made with little or no change in the time dependence of CA DS-1.7 film weight loss. In contrast, substituting tree leaves, food, meat, cow manure, and sawdust with steam-exploded wood in combination with either Rabbit Choice (Mix-D) or starch and urea (Mix-E) resulted in a significant time increase (from 7 to 12 days) for the complete disappearance of CA DS-1.7 films. Interestingly, in this work no direct correlation was observed between the C/N ratio (which ranged from 13.9 to 61.4) and the CA DS-1.7 film weight loss. Decreasing moisture contents of the compost Mix-2 from 60 and 50 and 40% resulted in dramatic changes in polymer degradation such that CA DS-1.7 showed an increase in the time period for a complete disappearance of polymer films from 6 to 16 and 30 days, respectively.Guest Editor: Dr. Graham Swift, Rohm & Haas.Paper presented at the Bio/Environmentally Degradable Polymer Society—Second National Meeting, August 19–21, 1993, Chicago, Illinois.     

汽车NVH测试评价方法

本文针对汽车NVH测试评价,分别从汽车NVH关注点、评价要求和条件做了介绍,并就汽车车内噪声、动力总成悬置隔振和支架共振频率、悬挂隔振特性等方面进行了较详细的实例评价.     

基于预测有效度一致的城市生活垃圾产生量预测

提出了基于预测有效度一致的城市生活垃圾产生量最优组合预测模型,该模型在组合预测之前利用Kendall一致性检验法对参加组合的单项预测模型值的拟合精度进行一致性检验,在通过检验之后再利用方差倒数法求解最优组合权重,建立组合预测模型。通过实例分析,表明其预测精度高于参加组合的各单项模型预测值,在城市生活垃圾产生量的预测工作中有一定的应用价值。     

超声波强化膜分离及清洗的研究进展

综述了超声波强化膜分离与膜清洗的机理,国内外超声波强化膜分离与清洗的研究现状以及影响该技术运用的问题所在。现有的研究成果表明:通过低功率超声波辐射处理污染膜可以减缓运行过程中的浓差极化及膜污染,而如何优化操作参数、如何减小超声波对膜体损害是近期的研究重点。     

伺服阀性能测试系统的研制

在LabWindows/CVI环境下,提出了基于PCDAQmx数据采集卡（6014）的伺服阀测试系统实现的原理与方法,并研究了伺服阀参数指标的算法.重点介绍了关键功能实现的方法,如流量特性曲线的测量及拟合算法、实现频率特性测试的关键技术及算法以及硬件接线自动控制的实现方法.     

总氮测定中应注意的几个问题

对总氮测定中影响空白值偏高的因素进行了实验和分析,并提出了改进意见。     

弹性滑移支座力学性能的试验研究

介绍了弹性滑移支座的原理、构造和特点;通过对其在不同工况下的性能试验,研究了竖向荷载、位移幅值以及加载频率对弹性滑移支座力学性能的影响,并给出了试验值与理论计算值之间的对比。研究结果表明:弹性滑移支座具有良好的工作性能,滞回曲线饱满,耗能能力强;竖向荷载和加载频率对弹性滑移支座的力学性能有一定的影响,而位移幅值对其影响较小;弹性滑移支座的恢复力模型,可以用考虑速度的指数摩擦力模型来描述,并且模拟得较为准确。     

文丘里洗涤过滤型FCVS性能评价述评及建议

通过调研对国内外文丘里洗涤过滤型FCVS性能评价进展进行了阐述与比较,指出国内开展文丘里洗涤过滤型FCVS出厂性能评价不全面,需进一步开展相关性能评价技术研究;FCVS在现场的安装质量如何,随着时间的推移性能变化如何,并未开展试验验证,结合法规要求等,建议开展FCVS现场试验评价技术的研究.     

US/UV联用降解荧光增白剂CBW的研究

对超声波、紫外联用技术降解荧光增白剂的反应进行研究，考察了辐射时间、超声功率、pH、H2O2投加量等因素对降解效率的影响。结果表明：荧光增白剂的降解效率受辐射时间影响较大，降解过程符合拟一级反应I提高超声波的功率可提高荧光增白剂的降解率；H2O2的添加，可使溶液中的氢氧自由基的浓度增加，从而提高了荧光增白剂的降解率。在初始浓度为40mg／L，超声功率为500w、pH为9、H2O2的添加量为30mL／L、反应120min的条件下，荧光增白剂的降解率可达95％。