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Up to derived equivalence, the representationfinite selfinjective algebras of class An are divided into the wreathlike algebras (containing all Brauer tree algebras) and the M?bius algebras.


Twisted Bimodules and Hochschild Cohomology for Selfinjective Algebras of Class An, II


This allows us to associate to every equivalence class an infinite family of graphs and determine their topological properties.


For convenience we call each structure of this new class an almost Cstructure, and a manifold with an almost Cstructure an almost Cmanifold.


In the first class an oval consists of the points of a conic together with its nucleus.

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 This paper reviews the developmental history of seismic stations and evaluates the detection capability of the present network of seismic stations in China. Similar results are obtained by the three methods proposed for the evaluation of detection capability,namely. ( 1 ) Estimation of the effective radius of observation; ( 2 ) Examination by means of the bvalue; and ( 3 ) Examination by the method of areal seismicity. Our examinations show that the present network can detect the earthquakes of magnitude above... This paper reviews the developmental history of seismic stations and evaluates the detection capability of the present network of seismic stations in China. Similar results are obtained by the three methods proposed for the evaluation of detection capability,namely. ( 1 ) Estimation of the effective radius of observation; ( 2 ) Examination by means of the bvalue; and ( 3 ) Examination by the method of areal seismicity. Our examinations show that the present network can detect the earthquakes of magnitude above 4.5 occurring throughout China and of magnitude above 4.0 occurring in a greater past of China. In eastern China whese the station density is higher,the detection capability is greater so that the earthquakes above 2.0 or 3.0 east of longitude 100?E can be detected.In this paper,the observation errors and their causes are also discussed. Analysis shows that the observation precission of the present network of seismic stations is not high,and that the uncertainty in the time service of "Class A Stations" is as much as±0.3 sec. Finally,suggestions are made for improving the observation capability through better distribution of seismic stations.  本文简略地回顾了中国地震台站的发展进程,对目前地震台网的实际监测能力进行了检验,并提出三项检验台网监测效能的方法,即(1)有效观测范围的估算,(2)b值检验和(3)地震活动面积的检验。经过检验表明,现有台网可以基本监测全国范围内4.5级和绝大部分地区4.0级以上的地震活动;东部地区的台站较多,其监测能力也较强,可观测到东经100°以东大部分地区的2.0级或3.0级以上的地震。 文中对地震台网的观测误差及其引起的原因进行了讨论。经分析后认为目前我国区域地震台网观测精度不高,甲类台站的时间服务才达到±0.3秒左右。最后,还对提高中国地震台网的监测效能和改善台网的布局提出了一些建议。  It can be seen by experiment that the operating conditions of two power transistors in Totempole output stage are different from each other. When one is of Class B the other must be of asymmetrical Class A. By an analysis of the circuit operating conditions, an important formula for its proper design is derived and ways to improve efficiency are proposed.  本文在实验的基础上,指出TotemPole功率放大器两个功率管的工作状态是不相同的.其中一个功率管工作在B类,另一个必须工作在非对称的A类.通过对这种电路的工作状态进行分析,提出了正确设计的重要公式和提高效率的方法.  This research attempts to find out the different effects of programmedinstruction and traditional instruction on students' achievement, learningtime, thinking ability and learning motivation. The experiment was carriedout in two firstyear classes (an experimental class and a control one) ina middle school, both of which were taught rational number in theiralgebraic course, and by the same teacher. The average level of the twoclasses was approximately equal in the beginning. The experimental classbegan... This research attempts to find out the different effects of programmedinstruction and traditional instruction on students' achievement, learningtime, thinking ability and learning motivation. The experiment was carriedout in two firstyear classes (an experimental class and a control one) ina middle school, both of which were taught rational number in theiralgebraic course, and by the same teacher. The average level of the twoclasses was approximately equal in the beginning. The experimental classbegan to use a programmed teaching material compiled by ourselves forabout a month, during which both classes were tested a few times and theirmarks compared. The results showed that the experimental class madeobviously better progress in all aspects than the control class. These resultsare probably related to the heuristic characteristics of programmed materials.Programmed instruction still needs further research.  本研究对程序教学与传统教学的效果作了对比。研究表明,程序教学可以缩短学习时间、提高学习效果、激发学习动机,有助于自学能力的培养。如果程序教材能够符合学生的认识规律,在教材中尽量增加启发因素,那么程序教学对于思惟能力的培养也可以起到积极的作用。   << 更多相关文摘 
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