Differential effects of norm-referenced and self-referenced feedback on performance expectancies,attributions, and motivation

When feedback is provided to students in a norm-referenced manner that compares the individual's performance to that of others, people who perform poorly tend to attribute their failures to lack of ability, expect to perform poorly in the future, and demonstrate decreased motivation on subsequent tasks. The present study examined the hypothesis that the deleterious effects of failure might be attenuated when failure is expressed in self-referenced terms—relative to the individual's known level of ability as assessed by other measures. In this study, subjects received feedback indicating that they did well or poorly on an anagram test, and this feedback was described as either norm-referenced (comparing the individual's performance to that of others) or as self-referenced (comparing performance to other measures of the individual's ability). As predicted, compared to norm-referenced failure, self referenced feedback resulted in higher expectancies regarding future performance and increased attributions to effort. Contrary to expectations, attributions to ability were not affected. The implications of the results for the structure of academic feedback are discussed.     

单裂隙承压无压条件下达西-非达西流演变试验研究

基岩裂隙水运移机理研究对基岩裂隙水水害防治以及污染修复具有重要意义。本文设计了由水泥和粗砂（粒径介于1 mm～2 mm之间）制成的单裂隙模型,开展了承压无压条件下基岩裂隙水流试验和拟合研究,讨论了水力梯度和流速之间的关系以及Forchheimer公式中线性项和非线性项的比例变化。得出主要结论如下：（1）实验条件下的水流呈非达西流,用Forchheimer公式可以较好地拟合水力梯度和流速的关系,且拟合精度较高。（2）随着离出水口距离的增加,水流从非达西流向达西流演变,当距离足够远时可以将水流视为达西流。（3）在水流从非达西流向达西流演变过程中,临界雷诺数随着隙宽的增加逐渐减小。     

另一个中世纪——苏珊·雷诺兹有关西欧中世纪共同体的认识

苏珊·雷诺兹是当代英国著名史学家,她从集体行为和集体意识的角度重新界定了共同体概念,因而扩大了共同体的含义。从这个角度,她把中世纪看作是由诸多共同体构成的社会。按这一认识,中世纪的领地、城市、王国本身,都是某种共同体。这种意义上的共同体与中世纪社会基本制度的关系并非二元对立,而是内在统一的。共同体在不同程度上维护着共同体成员的共同利益,体现着共同体成员共有的价值观念,但共同体并不是挣脱了封建制度和权力强制的自由、平等的小社会。中世纪人对王权的认同和对王国的归属感,以及王国政府对社会成员的集体行为和集体意识的依赖,表明各王国也呈现出共同体的很多特点。雷诺兹的诸多认识挑战了有关中世纪共同体问题研究的整个学术传统,向人们展现了另一个中世纪,富有启发意义,同时也留下了一些有待进一步探寻的问题。     

对流传热系数测定的探讨

测定了不同流速下的各种传热数据,用实验法和理论计算法给出管内热膜系数α测、α计、Nu测、Nu计及总传热系数K测、K计的值,分析了实际法和理论法得到的传热系数的区别.在传热管中加入螺旋弹簧作为强化元件后,对各种数据的计算及与理论值之间的差别进行了分析.     

The State Secrets Privilege and the War on Terror: An Annotated Bibliography

This selective annotated bibliography is a guide to scholarly articles about use of the State Secrets Privilege during the War on Terror. Use of the privilege became controversial during the presidential administration of George W. Bush, resulting in a scholarly debate over the privilege and the propriety of its use in litigation concerning measures taken by the United States government in the years following the terrorist attacks of 11 September 2001. This bibliography is intended to provide an overview of the scholarly literature to lawyers, scholars, and students.     

楔上再压区的理论分析与实验研究(英文)

在本文中,对于再压区,在流管微元上建立了连续性方程和动量方程。根据这些方程,确定了流线的位置及速度分布,从而得出了分路流线及再附着点的位置。尤其是沿分路流线解得了涡流扩散系数。在实验中,用双通道探头热线风速计测量了平均速度、湍流度及雷诺应力。实验数据的采样及处理是由Z—80SBC控制的。所得结果与参考文献作了比较,理论结果与实验数据非常符合。     

论粘性二元平行流动

作者从前文 [　 ]已得到的脉动流速微分方程 [10 ]出发 ,对于粘性二元平行流动这一类流动模式 ,进行分析、研究并得到了脉动尺度、脉动流速及雷诺应力的物理方程。在封闭的条件下 ,求解了所设定流动模式下的雷诺方程 ,解析得到沿边界法线方向的流速分布公式。希望本文的工作对湍流的半经验理论的理性化进展有所帮助。     

高速发动机油膜惯性对活塞裙润滑的影响

By an iteration method, the influence of oil film inertia on piston skirt lubrication in a high speed engine is investigated. By alternately solving the Navier-Stocks equations and the Reynolds equation, the new iteration method can trace the variations of velocity field and pressure field with time. Based on this, the mixed-lubrication model suitable for the piston skirt of high engines is proposed. By introducing the inertia coefficient, the new lubrication model includes the inertia term in oil film. The model can be also used to solve for the lubrication performances of a piston skirt in low or medium speed engines and for lubrication problem in general excluding     

一类改进的气体静压轴承压力场分布有限差分算法(英文)

针对传统的静压气体轴承压力分布算法效率较低或收敛性较差等问题, 提出了一类改进的有限差分计算方法. 以小孔节流式的径向静压气体轴承的压力分布为对象, 采用有限差分法求解非线性雷诺气体润滑方程; 根据流量平衡原理, 提出了一种新型变步长逐步逼近迭代算法, 用于修正迭代过程中的供气口出口压力, 提高算法的效率和收敛性; 基于Matlab工具, 开发了一套通用的径向静压气体轴承的压力场分布计算软件. 算例结果表明: 所提出的改进有限差分法计算效率高, 稳定性好, 收敛快; 对于小间隙(小于2 μm)气膜, 此方法仍然有效并快速收敛.