蒙古冷涡影响下的北京降雹天气特征分析   总被引：7，自引：3，他引：4       下载免费PDF全文

王在文  郑永光  刘还珠  沃伟峰  黄卓 《高原气象》2010,29(3):763-777

蒙古冷涡是诱生北京地区冰雹天气的一种主要天气系统,通过对近8年几例冰雹天气过程的分析,得出在蒙古冷涡影响下,北京地区产生的冰雹天气与其他天气类型相比,具有分布范围广、局域性强的特点。对蒙古冷涡影响下的天气形势进行详细分析,可以进一步将其分为两类,一类是蒙古冷涡后部强冷空气与前部暖湿气流交绥,地面强冷锋造成的对流天气;另一类是主冷锋后,蒙古冷涡后部不断南下的冷空气,与增温、增湿的地面低涡或切变线系统而形成不稳定大气层结造成的对流天气。同时该两类天气也有许多共同特征。如对流层低层的能量锋,大气的斜压性和层结的条件对称不稳定激发了能量锋前蕴酿已久的湿有效能量得到了有效的释放,导致对流不稳定天气的发展。对流层中层干冷空气的侵入,正的差动假相当位温平流加剧了大气层结的不稳定,强的风垂直切变更促使对流上升运动的发展。尽管这两类冰雹的各项特征的强弱程度不同,所产生的冰雹天气强弱也有差别,但都表现了有利于冰雹天气发生和发展的动力、热力特点。与其它个例比较,可以综合提出蒙古冷涡影响下冰雹天气的预报着眼点,为北京地区强对流天气潜势预报和临近预报提供理论依据。  相似文献   

抽芯验桩工作中应注意的几个问题     

隆威  牟一兵 《探矿技术》1998,(2):10-10

本文介绍了抽芯验桩的特点及适用性，并用实例阐明在抽芯验桩工作应注意的几个问题。  相似文献   

Research and development on foam breaking and recycling technology in air-foam drilling     

CAO Pinlu  ZHANG Jincheng  WU Xia  HUANG Jinyun Institute of Drilling Engineering Technology  Zhongyuan Petroleum Exploration Bureau  Puyang  Henan  China 《东北亚地学研究》2009,(4):204-209,214

In recent years, air-foam combining the advantages of both liquid and air drilling has been utilized as a drilling medium. Air-foam drilling has proved its efficiency in numerous situations where serious problems were encountered, such as in fractured formations and depleted or high permeable zones. However, the major disadvantage of air-foam drilling system is that the foam can only be used once, so that an extremely large pit is required to contain the foam to allow sufficient room for cuttings and for the foam to dissipate. Moreover, it needs enormous volume prepared, consuming abundance of water and ingredient additives, which results in the high cost of foam drilling. The recycling foam fluid by using foam breaking technology is the only effective method to solve these problems associated with the known foam drilling. Various types of equipment and technique have been employed to suppress foam formation in biological and process equipment in foam drilling. The study described various methods of foam breaking technology, and the trend of the foam breaking technology for foam drilling is discussed.  相似文献   

Calculation of flow distribution in air reverse circulation bit interior fluid field by simplifying air flow model     

Shuqing HAO  Hongwei HUANG  Kun YIN. Department of Geotechnical Engineering  Tongji University  Shanghai  China. College of Construction Engineering  Jilin University  Changchun  China 《东北亚地学研究》2007,10(2):190-195

By simplifying the characters in the air reverse circulation bit interior fluid field, the authors used air dynamics and fluid mechanics to calculate the air distribution in the bit and obtained an equation of flow distribution with a unique resolution. This study will provide help for making certain the bit parameters of the bit structure effectively and study the air reverse circulation bit interior fluid field character deeply.  相似文献   

青岛团岛汇水区域污水处理对胶州湾口水质改良的贡献     

刘如玲  马启敏 《海洋湖沼通报》2009,(1)

青岛团岛地区入海的主要水污染源,是来自其汇水区城内的大量生活污水和一定量的轻工业废水.自1998～2007年底,累计处理污水14254万吨,削减各类有机物如CODcr、BOD、SS以及NH4-N、TP等污染物累积28万吨,为减轻胶州湾口的水环境污染起到一定的作用.团岛污水厂采用"生物脱氮除磷A/A/O"工艺,自运行以来,不断提出一些优化方案以改善污水处理效果,使出水COD、BOD5、SS、NH4-N、TP等指标达到并优于国家二级排放标准(GB18918-2002),提高了排入胶州湾口的水质质量.  相似文献   

Transpiration rates of Carex Meyeriana in relation to micrometerological factors in a mountain valley wetland     

Huifeng Xu  Yanming Jin  Wei Deng  Kezhang Xu  Zhen Wang 《山地科学学报》2009,6(3):293-298

In order to reveal transpiration rates of wetland plants and its relationships to micro- meterological factors in a mountain valley wetland, relative humidity, air temperature, leaf temperature, soil temperature, photo flux density and transpiration rates were measured once two hours in a Carex meyeriana wetland of the Changbai Mountain valley in dry （July） and wet （September） of 2003, respectively. Results showed that the tendency of ＂decreasing after increasing＂ was obvious in wet season. However, a relatively stable trend was observed for the transpiration in dry season.. Generally, the photon flux density of Carex meyeriana was higher in wet season than that in dry season. However, the variabilities of leaf temperature, air temperature and relative humidity were similar in both seasons. Higher transpiration rates of Carex meyeriana leaves were observed in July （varied from 40 to 150 mol.m^-2.s^-1） compared to those （varied from 7 to 14 mol.m^-2.s^-1） in September. Transpiration rates were significantly correlated with air temperature （P〈0.01）, leaf temperature （P〈0.01）, and wind speed （P〈0.05）, but correlationship between relative humidity and photo flux density was not significant （P〈0.05）.  相似文献   

非开挖铺管技术在石门电厂灰坝排渗系统施工中的应用     

胡光林 《湖南地质》2009,(5):69-71

介绍了导向钻进和顶管两种非开挖铺管技术在石门电厂灰库坝排渗系统施工中的应用，总结了其成功的经验，为类似工程的施工、设计提供了参考。  相似文献   

超深井钻进技术与工艺     

应大勇 《工程勘察与施工信息》1998,(1):21-23

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基岩深管井结构与成井新工艺     

周勇翔  吴进省  全宏博  刘前锋 《地下水》2001,23(1):53-54

1　前言陕西咸阳北部的永寿、旬邑、淳化、彬县、长武属渭北旱塬丘陵沟壑区 ,覆盖层厚度与基岩埋深变化大 ,地下水资源贫乏 ,且赋存不均 ,开采难度大 ,费用高 ,许多地方群众的生活用水尚未解决 ,更谈不上农作物灌溉。水严重制约着当地脱贫致富、经济发展和社会进步。带着这一课  相似文献   

硅灰石合成多孔二氧化硅 ——工艺条件与产物性质研究   总被引：4，自引：1，他引：4  

陈庆春  王廷吉  周萍华  彭人勇  CHEN Qing-chun  WANG　Ting-ji  ZHOU Ping-hua  PENG Ren-yong 《华东地质学院学报》2001,24(1):64-66

在一系列硅灰石酸处理实验基础上，研究了产物性质与反应速度、反应时间、中和最终pH值等工艺条件的关系。结果表明，工艺条件不同，物理性质也大不相同。  相似文献