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211.
Run-Qian Huang Han-Feng Song Shao-Lan Bi National Astronomical Observatories/Yunnan Observatory Chinese Academy of Sciences Kunming Graduate University of Chinese Academy of Sciences Beijing 《中国天文和天体物理学报》2007,7(2):235-244
Three importantphysical processes occurringin contact binarysystems are studied. The first one is the effect of spin, orbital rotation and tide on the structure of the components, which includes also the effect of meridian circulation on the mixing of the chemical elements in the components. The second one is the mass and energy exchange between the components. To describe the energy exchange, a new approach is introduced based on the understanding that the exchange is due to the release of the potential, kinetic and thermal energy of the exchanged mass. The third is the loss of mass and angular momentum through the outer Lagrangian point. The rate of mass loss and the angular momentum carried away by the lost mass are discussed. To show the effects of these processes, we follow the evolution of a binary system consisting of a 12M and a 5M star with mass exchange between the components and mass loss via the outer Lagrangian point, both with and without considering the effects of rotation and tide. The result shows that the effect of rotation and tide advances the start of the semi-detached and the contact phases, and delays the end of the hydrogen-burning phase of the primary. Furthermore, it can change not only the occurrence of mass and angular momentum loss via the outer Lagrangian point, but also the contact or semi-contact status of the system. Thus, this effect can result in the special phenomenon of short-term variations occurring over a slow increase of the orbital period. The occurrence of mass and angular momentum loss via the outer Lagrangian point can affect the orbital period of the system significantly, but this process can be influenced, even suppressed out by the effect of rotation and tide. The mass and energy exchange occurs in the common envelope. The net result of the mass exchange process is a mass transfer from the primary to the secondary during the whole contact phase. 相似文献
212.
REE geochemical characteristics of the No. 302 uranium deposit in northern Guangdong, South China 总被引:1,自引:0,他引:1
ZHANG Guoquan HU Ruizhong BI Xianwu FENG Haisheng SHANG Pengqiang TIAN Jianji 《中国地球化学学报》2007,26(4):425-433
The No. 302 uranium deposit, located in Guangdong Province, is a typical granite-type uranium ore deposit REE geochemical characteristics of the wall rocks, pitchblende, altered rocks, calcite and fluorite from this deposit have been systematically studied in this paper. The result showed that the alkali-metasomatic granites and other altered rocks have the same REE distribution patterns as Indosinian granites. It is indicated that the hydrothermal ore-forming solution had altered the Indosinian granites, and ore-forming materials may directly originate from the Indosinian granites. Calcite and fluorite of different stages are the products derived from the same source but different stages. The evolution and degassing of the mineralizing solution might induce LREE enrichment to varying degree. Mantle fluid and a large volume of mineralizer may be the crucial factors controlling uranium mineralization, and the hydrothermal solution with mineralizer played an important role in U transport and concentration. Meanwhile, the degassing of CO2 might promote U and REE precipitation. 相似文献
213.
河南一次强降水过程云和降水结构的中尺度数值模拟 总被引:1,自引:0,他引:1
用中尺度数值模式(MMSv3.7)模拟了2005年6月25-26日河南一次强降水天气过程。模式计算的整层积分所有水凝物总含水量、模拟的雷达回波特征、24小时雨量分布、强降水阶段雨量时变特征与实况对比均具有比较好的模拟能力。在此基础上利用模式输出的资料分析了强降水形成的湿热力动力条件、降水区不同位置不稳定指数以及强降水区各种水凝物随时间的变化,并用Reisner霰方案计算出的雪、霰、冰晶、雨水、云水比含量资料,对比分析了降水初生和显著增强两个阶段云中的微物理结构特征的差异。 相似文献
214.
利用燕山南麓1951-2005年夏季降水资料和NCEP再分析资料,采用统计分析等方法,对燕山南麓夏季降水演变规律进行了研究.结果表明:近55 a来,燕山南麓夏季降水线性减少趋势显著,平均每10 a年减少29 mm,夏季降水在20世纪70年代末发生了一次气候突变.燕山南麓夏季降水和东亚夏季风变化周期不一致.燕山南麓夏季降水减少主要是由于亚洲中纬度地区和极地地区环流变化造成的. 相似文献
215.
E. Biémont 《Solar physics》1978,56(1):79-86
Oscillator strengths calculated by the STF method for selected transitions of V i and Co i have permitted to deduce, from an LTE study of weak lines, photospheric abundances in agreement with those obtained from carbonaceous chondrites. A summary of results is also presented for all the iron-group elements. 相似文献
216.
TPC 及 DLC理论在旅游产品再开发中的应用——昆明市案例研究 总被引:23,自引:1,他引:22
从旅游产品再开发的角度出发,应用市场营销学的TPC理论和旅游地理学的DLC理论,对昆明市的病例进行分析,提出了昆明市旅游产品再开发战略的方向、原则和发展重点。 相似文献
217.
CT胃仿真内窥镜成像技术临床应用的探讨 总被引:2,自引:0,他引:2
目的:探讨CT胃仿真内窥镜成像技术的原理,方法,临床应用材料与方法:将螺旋CT容积扫描数据传输到工作站,通过软件功能重建出沿空腔器官中轴行程一致的多幅器官内表面图像,再用电影功能一次回放,获得仿真内窥镜效果用此方法检查10例及正常人其中胃部疾病患者5例.全部病例均经胃纤维内窥镜及手术病例证实结果:胃仿真内窥镜获得类似纤维内窥镜显示空腔器官腔壁或腔内病变形态的效果结论:CT胃仿真内窥镜提供了一种无创伤性的诊断方法,可作为纤维内窥镜的补充手段. 相似文献
218.
219.
STUDY ON UNIFIED INTER-SPHERICAL ACTING OF CONTINENTAL COLLISION OF TIBET PLATEAU 相似文献
220.
I~ODWrIONExtraction of DNA from Porphyra po~nsis is very difficult due tO its high content ofpolysaccharides. TO avoid the interference Of POlysaccharides, HOng et al. (1992) used LiCI tosoften Porphyra thalli cells to release DNA directly without lysing the thalli, hoWever, the procedure is problematic in the isolation of high-quality DNA. Kitade et al. (1996) established a complicated procedure which includes the grindiflg of material in liquid nitrogen, lysing of material inextra… 相似文献