New representation of Maxwell relation

A new representation of the Maxwell relation for phase transformation is given, which is expressed in simpler form and has more direct physical meaning than the original Maxwell relation. It is shown that the physical conjecture for the so-called “lock-up” condition suggested by Jensen （1999） is correct, but the equation for the “lock-up” condition suggested by Jensen （1999） is not. Numerical examples also demonstrate that the application of the new representation of Maxwell relation gives exactly the same solutions as the ones with application of the original Maxwell relation and, however, application of the “lock-up” condition gives no real solutions.     

Cheating: The illusory edge

This experiment studied the relationships among cheating, overall test performance, and the relatedness of materials available and unavailable to the cheater. Subjects learned a free-recall list and were then tested for recall either when cheating was impossible or when half of the list had been left “carelessly” exposed. For half of the cheat subjects the exposed and the unexposed words belonged to different categories, while for the remaining halves the items belonged to the same categories. Recall was scored for both exposed and unexposed words. The results indicate that significant cheating did occur, that cheating did not improve overall performance, and that while cheating elevated the numbers of recorded exposed words it depressed recall of stored unexposed items (for both related and unrelated sets). This associated cost effect is discussed in connection with category retrieval, output interference, attention, and arousal.     

电偶极和磁偶极辐射的SO(2)对偶理论

在引入Drac磁单极(即磁荷)的情况下，首先介绍了Maxwell方程双矢势下的电磁对偶性．接着给出了有磁荷存在的d‘Alembert方程，利用这个方程推迟解求出了带磁荷粒子和双荷粒子的电磁辐射的表达式,最后讨论了电偶极和磁偶极辐射在双矢势下的表达式。     

Prose organization and recall

In two experiments, subjects read prose materials with various organizations of the superordinate and subordinate conceptual structure of the passage. Variables included organizational salience, massed versus distributed repetition of the passage, nature of the cueing at recall, and number of exposures. In Experiment I, distributed repetition resulted in superior recall, extending the generality of that effect to prose materials; and an advance organizer treatment resulted in lower recall for scrambled materials, contrary to Ausubel's (1960) cognitive theory. High ability subjects recalled more categories than low ability subjects, but the same amount of within-category information. In Experiment II, materials which increased the salience of the organizational structure of the passage were better recalled than scrambled materials after three exposures, or on a test which cued the major categories in the passage. Cueing was detrimental to performance for subjects reading the scrambled passage. Results are discussed in terms of implications for educational practice.     

论洛克的政府理论

依据<政府论下篇>,洛克以政府的产生、政府的法治和内部分权原则、政府与政治社会的关系等为主要内容构建了自己的政府理论.洛克的政府理论既包含了合理、进步的一面,即为创建有限政府和保障消极自由提供了理论资源;又由于他难以驾驭从自然状态到政治社会的变迁而遭遇了理论困境,即具有理想主义的色彩、在政府产生问题上不具有解释力以及无法落实人民主权.     

在理想状态下Navier-Stokes和Maxwell方程初始边值问题的整体唯一可解性

在二维或三维有界域Navier-Stokes和Maxwell方程耦合下的整体唯一可解性初边值问题。该系统给出了一个确定性描述的动态进行,理想状态下不可压缩,均质流体。改进的结果,证明了周期性边界条件情况。     

Speech as process: Effects of experimental design

The traditional design for the study of language variables is a controlled message design in which one kernel message is manipulated to produce message variations that represent the language variable contrasts. Thus message content is the same across treatment conditions and hence crossed with the treatment factors. Jackson and Jacobs (1983) criticized this design on three grounds. They argued that messages should be natural rather than contrived, that messages should be nested within treatment conditions rather than crossed with treatment factors, and that each study should use as many messages as possible. Their paper has been used by reviewers as the basis for rejecting studies done using the traditional design. This paper presents a detailed analysis of the arguments presented in Jackson and Jacobs (1983) as well as subsequent papers by Jackson (1984) and Jackson and Jacobs (1987). The arguments are shown to contain both methodological and substantive errors. When the arguments are corrected, it is shown that nested designs and multiple messages should be used only when absolutely necessary. It is the traditional controlled message, crossed design and not the naturalistic message, nested design which is robust; robust against not only incidental but fundamental confounding, robust against message by treatment by message interactions, and relatively robust against Type II error. Taken together with meta‐analysis, the traditional single message, crossed design can detect and identify message by treatment interactions. On the other hand, the multiple message design makes it impossible to identify such interactions.     

基于ANSYS/Maxwell的感应滤波配电变压器设计与实验研究北大核心

该文提出了一种适用于低压配电网系统下的新型感应滤波配电变压器设计方法,并将其应用于综合性创新实验的教学案例中。在感应滤波配电变压器的设计中,将感应滤波技术应用于采用Ddy联结组别的配电变压器中。通过建立电路数学模型,推导阀侧产生的谐波电流与网侧电流之间的关系,揭示感应滤波配电变压器的滤波特性。该文采用ANSYS/Maxwell软件建立新型变压器的3D模型,在模型上通过仿真能量法对比工程磁路法,验证变压器绕组间短路阻抗满足技术要求;并通过磁路耦合添加滤波支路,监测变压器的网侧电流,验证其可以有效滤除电网谐波污染。最后通过实验验证了所设计的变压器的正确性和有效性,进一步激发了学生的学习兴趣和创新热情。