半群环成为预布尔环

本文给出半群环ＲＳ（其中：Ｒ为环，Ｓ为半群）为预布尔环的条件为：环Ｒ为指数３的幂零环，且Ｓ为任一可交换半群；或者Ｒ为指数３的预布尔非幂零环，且Ｓ为预布尔半群．     

Variations of the spring precipitation day numbers reconstructed from tree rings in the Urumqi River drainage,Tianshan Mts. over the last 370 years

The tree-ring cores of Tianshan spruces col-lected from nine sites in the Urumqi River drainage of the middle Tianshan Mountains were used to establish three types of the tree-ring width chronologies over the last 370 years, using the international standard method of dendro-chronology. Our study demonstrates that dendrochronologycan be better used to reconstruct the number of the precipi-tation day than to reconstruct the precipitation amount in middle Tianshan Mountains. It is found that the residual chronology among the three tree-ring width chronologies has the best relationship with number of spring precipitation days from May 20 to June 8. The chronologies at Haxiong-gou B site and Zaierdegou site in the Urumiqi drainage have the highest correlation with the observed number of spring precipitation days at Daxigou meteorological station, and are used to reconstruct the spring precipitation days over the last 370 years in the drainage. The main significant decreasing trend of the number of the spring precipitation days oc-curred during 1665--1717, while the significant increasing trends happened during 1805--1841 and 1914--1943. The reconstructed series of the number of spring precipitation days has quasi-periodic variations of 3.3, 2.1, 2.5, 12.3 and 32.0 years with the dominated short periodical changes. The long cycle of 32 years is shown quite clearly in the 10-year smoothed sequence. The maximum spring precipitation days occurred mainly in the 1630s, 1840s and 1940s, while the lowest number of spring precipitation days for the 10-year average occurred in the 1710s.     

Temperature and precipitation in Mongolia based on dendroclimatic investigations

Recent tree-ring studies in Mongolia provide evidence of unusual warming that is in agreement with large-scal reconstructed and recorded temperaturec for the Northern Hemisphere and the Arctic.One Mongolian proxy record for temperature extends back over 1000 years and several others are over 350 years in length.Precipitation reconstructions based on thee rings reflect recent increases but also indicate that the increases are within the long-term range of varlations.Spectral analyses of recorded preciplta-tion data and the reconstructions support the hypotheses of quasi-solar periodicity in precipitation variation,previously suggested by others.     

空问机构自由度计算

从四杆机构具有灵活性和平面机构任意封闭图形具有3个约束的理论出发，对机构学的自由度公式进行了研究。研究结果表明：只要对平面、球面机构自由度的计算公式稍加变化，推导出空间机构求自由度的新公式。利用这个新公式，既可以求空间机构的自由度，又可以求平面、多环、空间开式链、混合链等机构的自由度。它比传统公式使用简便，在形式和内容上都有实际意义，从而为空间机构自由度的计算提供了可靠的理论计算式。     

分次环的群环的强素根与分次强素根

研究了分次环的群环的强素根与分次强素根 ,并刻划了分次环的群环R[G]—分次模的半单性     

弹性分组环技术（RPR）

弹性分组环(RPR)技术是一种基于以太网技术和标记交换技术相结合的，多业务共存的业务特性的新一代城域网解决方案。主要介绍了弹性分组环(RPR)的MAC协议帧结构，探讨了RPR的基本原理、关键技术和光以太网RPR，并对RPR技术在未来通信网中的发展趋势进行了分析。     

EP-内射环的等价刻画及性质

给出了EP 内射环的几种等价刻画,证明了半素右EP 内射环的每一个极大右(左)零化子是由一个幂等元生成的极大右(左)理想.     

PS环的一些刻画

利用非奇异模、极小内射模，给出PS环的一些刻画，同时刻画了半单环，指出右YJS环、右DS环与右PS环之间的关系及它们等价的条件。     

巨型功率晶体管场限环研究

通过解联立一维泊松方程得到了场限环结构的电场和电位分布.讨论了环间距、环宽、N-掺杂浓度、结深和表面电荷密度等参数的影响,得出了归一化击穿电压和环间距计算值.用这些计算值可以推算多环间结构的击穿电压和作为场限环设计的依据.