Composite spectra     

R. & R. Griffin 《Journal of Astrophysics and Astronomy》1990,11(3):281-290

HD 201270/1 is a composite-spectrum binary whose components have spectral types close to G8 III and A2 V. They are in a circular orbit with a period of only 40 days. Photometric variability of RS CVn character is therefore not unlikely  相似文献   

The 14-year Performance of a Compacted Clay Liner used as Part of a Composite Liner System for a Leachate Lagoon     

Craig?B.?LakeEmail author  R.?Kerry?Rowe 《Geotechnical and Geological Engineering》2005,23(6):657-678

The migration of contaminants through a 2.9 m thick compacted clay liner (CCL) for a landfill leachate lagoon is examined 14 years after construction. The clay liner formed the lower portion of the composite liner system but the geomembrane (GM) was found to have defects that had allowed leachate to migrate between the GM and CCL. Chloride, sodium, potassium, calcium and magnesium pore water profiles through the CCL are examined. It is shown that chloride migrated approximately 1.7 m into the CCL during the 14 years of the lagoon operation, sodium approximately 1.2 m, and potassium 0.7 m. Diffusion and sorption data from laboratory diffusion testing are utilized in combination with a finite layer contaminant transport model to predict field contaminant migration profiles through the composite liner system and to establish the time of ‘failure’ of the geomembrane at sometime between 0 and 6 years after installation. Relatively high sorptive uptake of potassium by the CCL soil is observed from batch testing and diffusion testing with field data suggesting an even larger amount of sorption. It is hypothesized that organic sludge matter at the base of the lagoon is responsible for potassium uptake from the leachate. This field case highlights the importance of the compacted clay liner as part of the composite liner system in acting as a diffusion barrier during the lifetime of the lagoon as well as using relatively non-conservative contaminants such as chloride and sodium to estimate geomembrane ‘failure’ times  相似文献   

近20年我国气象灾害损失的初步分析   总被引：8，自引：1，他引：7  

陈云峰  高歌 《气象》2010,36(2):76-80

利用1989—2008年的全国自然灾害灾情资料,采用综合集成评价方法计算出气象灾害损失的综合指数,运用聚类分析法对近20年的气象灾害损失进行定级并分析其随时间的变化。结果显示,20年中前10年气象灾害的损失比较大,后10年损失显著减小;气象灾害导致的人口死亡数在近20年中呈明显的下降趋势;1991、1994、1996、1998年为气象灾害的重灾年。  相似文献   

一次局地暴雨过程的多普勒雷达特征分析   总被引：1，自引：1，他引：0  

彭军  高卫飞  张琼 《沙漠与绿洲气象(新疆气象)》2010,4(1):28-31

利用库尔勒多普勒天气雷达资料,对2008年5月发生在新疆巴州焉耆盆地的一次局地暴雨过程的回波特征进行分析。降水过程中,在库尔勒到焉耆盆地一带先后有两次飑线发展东移,是造成局地暴雨的中小尺度系统。径向速度所反映的在库尔勒到焉耆盆地一带低空存在明显的垂直风切变,雷达西南方向长时间维持西南气流,为暴雨提供了水汽辐合及垂直向上输送的动力条件。  相似文献   

综合气象因素对广西电力负荷的影响   总被引：5，自引：0，他引：5  

钟利华  李勇  叶殿秀  张强  况雪源  张宇平 《气象》2008,34(5):31-37

针对电网负荷易受多种气象因素影响的特点,为综合衡量气象因素对广西电力负荷的影响,引入了气象学指数--有效温度,分析了4-10月气温、相对湿度、风及有效气温对电力负荷的影响.结果表明:气温与电力负荷呈显著的正相关关系,气温是影响电力负荷的主要因子;夏季以气温和风速、气温和相对湿度组合的变化对负荷的影响较大,风速从静风到有风时,负荷明显地减少,但当超过一定的温度时,风速越大负荷反而增加;6-9月,负荷随着气温和有效温度的升高呈线性增加;在春夏、夏秋季过渡季节,负荷并不完全随着气温的升高而增加,在气温不是太高的阶段,相对湿度增大时,负荷有下降的趋势,当超过一定的温度时,负荷随气温和有效温度的升高而增加.  相似文献   

Further Study of Typhoon Tracks and the Low-Frequency(30-60 Days)Wind-Field Pattern at 850 hPa          下载免费PDF全文

TIAN Hu  LI Chong-Yin 《大气和海洋科学快报》2010,3(6):319-324

The association of typhoon tracks over the western Pacific with the low-frequency wind-field pattern of atmospheric intraseasonal (30-60 days) oscillation at 850 hPa is further studied by using observational data analyses. Comparative analyses of the composite wind fields at 850 hPa, contrasting the atmospheric intraseasonal oscillation (ISO) with the original circulation, show that the typhoon tracks are closely related to the wind pattern of the ISO but are not obviously related to the original wind fields. Case studies of two typhoons in 2006 also show that the low-frequency wind-field pattern, particularly the maximum-value line (belt) of low-frequency cyclonic vorticity at 850 hPa, is closely related to the typhoon track. Therefore, the low-frequency circulation pattern and the maximum-value line (belt) of low-frequency cyclonic vorticity at 850hPa can be used to predict typhoon tracks over the northwestern Pacific.  相似文献   

The Relationship of Land-Ocean Thermal Anomaly Difference with Mei-yu and South China Sea Summer Monsoon     

WANG Zhifu  QIAN Yongfu 《大气科学进展》2009,26(1):169-179

Based on the NCEP/NCAR reanalysis data for the period of 1948--2004 and the monthly rainfall data at 160 stations in China from 1951 to 2004, the relationships among the land-ocean temperature anomaly difference in the mid-lower troposphere in spring (April--May), the mei-yu rainfall in the Yangtze River-Huaihe River basin, and the activities of the South China Sea summer monsoon (SCSSM) are analyzed by using correlation and composite analyses. Results show that a significant positive correlation exists between mei-yu rainfall and air temperature in the middle latitudes above the western Pacific, while a significant negative correlation is located to the southwest of the Baikal Lake. When the land-ocean thermal anomaly difference is stronger in spring, the western Pacific subtropical high (WPSH) will be weaker and retreat eastward in summer (June--July), and the SCSSM will be stronger and advance further north, resulting in deficient moisture along the mei-yu front and below-normal precipitation in the mid and lower reaches of the Yangtze River, and vice versa for the weaker difference case. The effects and relative importance of the land and ocean anomalous heating on monsoon variability is also compared. It is found that the land and ocean thermal anomalies are both closely related to the summer circulation and mei-yu rainfall and SCSSM intensity, whereas the land heating anomaly is more important than ocean heating in changing the land-ocean thermal contrast and hence the summer monsoon intensity.  相似文献   

登陆台风降水的大尺度环流诊断分析   总被引：4，自引：0，他引：4  

程正泉  陈联寿  李英 《气象学报》2009,67(5):840-850

强度相似的登陆台风造成的强降水可能差异很大.为研究大尺度环流对登陆台风降水的影响,利用热带气旋年鉴和NCEP/NCAR再分析资料,运用动态合成分析方法,对比分析了登陆后48小时内降水特征迥异而强度、路径相似的两组登陆台风的大尺度环流特征.合成分析结果表明,西南气流的水汽输送对台风降水至关重要,造成大范围强降水的台风往往在登陆后仍与深厚西南急流相连并持续很长时间.高空强辐散场是登陆台风造成大范围强降水的一个基本动力特征.造成强降水的登陆台风其环境场的上升气流不仅强,其气旋性环流的伸展高度高且能长时间维持.登陆台风造成降水的范围和强度与登陆前台风下游大陆环境大气的稳定度有关.下游高温高湿的大气有利于能量尤其是潜热能的大量补充,对强降水增强和维持都十分有利.因此,大尺度环流对登陆台风降水有明显影响.其中,与台风相连的西南急流强度和深厚程度是最重要的因子,高低空辐散辐合强度、台风及环境风场结构以及台风下游大陆上空大气湿热状态等都是需要加以考虑的.  相似文献   

湖南九嶷山复式花岗岩体SHRIMP锆石定年及其地质意义   总被引：53，自引：11，他引：42  

付建明  马昌前  谢才富  张业明  彭松柏 《大地构造与成矿学》2004,28(4):370-378

应用SHRIMP锆石U-Pb法获得九嶷山复式花岗岩中的主要岩体形成年龄为:雪花顶花岗岩(432±21)Ma、金鸡岭花岗岩(156±2)Ma、砂子岭花岗岩(157±1)Ma和西山火山-侵入杂岩(156±2)Ma。结果显示砂子岭岩体属燕山早期而非印支期;西山火山-侵入杂岩属燕山早期而非燕山晚期。花岗岩中继承锆石复杂,其形成时代为1579Ma、2108Ma和2669Ma,提供了九嶷山地区存在古-中元古代,甚至太古代基底的年龄信息。新元古代(912Ma)锆石的大量出现为扬子陆块和华夏陆块碰撞带通过本区的认识提供了一个间接证据。  相似文献   

基于混料设计的WC基复合胎体性能研究          下载免费PDF全文

黄帆  肖冬顺  瞿霞  赵小军  谭松成 《探矿工程》2019,46(1):89-92

采用混料设计方法,研究了WC、YG8、663-Cu含量变化对WC基复合胎体抗弯强度的影响规律。3种成分含量变化对抗弯强度有显著性影响,呈线性模型关系,得出了相应的回归方程。三者之间的影响大小是YG8＞WC＞663-Cu;3种成分含量变化对强度损失率影响很小,通过调整三者的成分比例,无法有效地提高胎体对金刚石的把持力。  相似文献