应用农田水量平衡模型估算土壤水渗漏量   总被引：15，自引：0，他引：15       下载免费PDF全文

龚元石  李保国 《水科学进展》1995,6(1):16-21

建立了一个农田水量平衡模型。并据于模型假设的条件,模拟计算了在冬小麦-夏玉米及冬小麦-裸地条件下历年1m土层土壤水渗漏量。结果表明,土壤水渗漏量与季节内降水量呈正相关,但在不同作物种植制度下有不同的相关关系式。不同水文频率年型下的渗漏量具有明显的差异,湿润年型下比干旱年型下的渗漏量多70～140mm,冬小麦-裸地比冬小麦～夏玉米种植条件下的渗漏量多30～50mm。  相似文献   

二维动力—物理气候模式的建立和发展     

李维亮  王维强 《南京气象学院学报》1993,16(3):257-268

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风速垂直变化对催化剂扩散的影响     

申亿铭  陈吉航 《气象》1993,19(10):7-11

在寻求层状云中催化剂扩散议程的解时，一般都假定风速为常值，但实际上风速是随高度变化的。该文在云中催化剂的数值模式中考虑了风速随高度的变化，用差分格式求其解，并进行了个例计算和比较分析。  相似文献   

不发达地区区域开发的几个理论问题   总被引：10，自引：0，他引：10  

汪一鸣 《地理学报》1993,48(6):497-504

本文在论述区域发展一般原理的基础上,分析了不发达地区的特殊性、不发达地区经济起飞必须具备的前提条件,肯定了国家干预对不发达地区开发的作用,提出了不发达地区区域开发的目标选择及综合开发战略。  相似文献   

宣传贯彻《矿产资源法》促进依法治矿     

龚静夫 《湖南地质》1991,(1)

《矿产资源法》颁布实施五周年,通过宣传贯彻,增强了广大干部、群众依法办矿的法制观念,推动了各项矿管工作的开展,依法办矿的矿山取得了采矿权,非法采矿的小矿山被关闭,违法行为受到查处,矿管部门的声望越来越高,促讲了依法治矿。宣传贯彻《矿产资源法》要领导首先学法,提高认识,加强领导,建立一支专兼结合的宣传队伍,采取多种形式有重点地进行宣传教育。我国、我省面临矿产资源形势是严峻的,浪费矿产资源的现象仍存在,要继续深入宣传贯彻《矿产资源法》。  相似文献   

A wind tunnel study of turbulent dispersion over two- and three-dimensional gentle hills from upwind point sources in neutral flow     

Wanmin Gong 《Boundary-Layer Meteorology》1991,54(3):211-230

A study of turbulent dispersion over hills for upstream, elevated sources was conducted, based on wind tunnel tracer gas (CO₂) experiments over a gentle 2-D ridge and a 3-D circular hill, both having a cosine-square cross-section. The concentration measurements were made with four different source locations for each hill case (2-D or 3-D), and the study focused on dispersion parameters under the influence of the presence of the hills in order to provide a better understanding of the mechanisms involved.The wind tunnel measurements show that, in the case of gentle hills, the topographic impact on turbulent dispersion from upstream sources is only moderate and is more pronounced for the 3-D than for the 2-D hill. The perturbation in mean flow introduced by the hills, including streamline divergence/convergence, is shown to dominate the changes in the dispersion due to the hills in this case. The plume spread, both in the lateral and the vertical, is enhanced over the upwind hill foot and reduced over the hill top in response to the mean flow slow-down and speed-up at these places, and is further enhanced or reduced due to streamline divergence/convergence in the vertical over the hills as well as in the horizontal over the 3-D hill. These results are also compared with cases of turbulent dispersion over more steep hills (Snyder and Britter, 1987).  相似文献   

加热法消雾所需热量和增温效应的计算方法   总被引：1，自引：0，他引：1  

申亿铭  陈吉航 《气象学报》1991,49(4):586-589

雾是人们熟知的一种常见的天气现象。它有利于农业生产和果树栽培,但对各种交通运输都会产生障碍和困难,严重时还可能发生意外事故;对于军事活动利弊兼有;在严重污染的城市中出现雾时,由于有毒的化合物质,轻则发生中毒现象,重则出现居民死亡。所以雾对于国民经济、交通运输、军事活动乃至人类的生命健康都有直接和十分密切的关系。因此很早以来,人类就开始了人工消雾的试验,  相似文献   

Chemistry and Evolution of Fergusonite—Group Minerals,Bayan Obo,Inner Mongolia     

Gong Weiliang 《中国地球化学学报》1991,10(3):266-276

A new classification scheme of the fergusnoite-group minerals is suggested on the basis of mineral chemistry and high temperature XRD. A number of new varieties such as M-thorian fergusonite-(Ce). M-neodymian fergusonite-(Ce). T-titanian fergusonite-(Nd) and T-yttrian fergusonite-(Nd) have been recognized in the light of detailed chemical studies, particularly with reference to REE, SRE and solid solution relationship. The results indicate strong REE and SRE differentiation and evolution in the fergusonite group, which can be interpretated by differences in the stability of various REE complexes in response to variations in physicochemical conditions during the multi-stage mineralization process in the Bayan Obo ore deposit. The crystallization of the minerals is closely related to hydrolysis of REE and Nb complexes. REE (OH)₃ Nb(OH)₅ coprecipitation, dehydration, polymerization and nucleation.The significance of SRE (Eu)in the western part of the deposit is emphasized. This project was finantially supported by the National Natural Science Foundation of China.  相似文献   

运用人工神经网络作汛期降水预报   总被引：2，自引：0，他引：2  

蔡煜东  宫家文 《气象科学》1994,14(4):386-389

本文提出汛期降水预报的人工神经网络方法，并选择一组标样进行了具体分析，预报成功率达100％，结果表明，该方法性能良好，可望成为汛期降水预报的有效手段。  相似文献   

BALLOON-BORNE MEASUREMENTS OF AEROSOL VERTICAL DISTRIBUTIONS OVER BEIJING DURING THE SUMMER AND AUTUMN OF 1993          下载免费PDF全文

Zhou Jun  Tan Kun  Shao Shisheng  Gong Zhiben  Shi Guangyu  Guo Jiandong  Wang Biao  Zhang Baowu  Sun Baolai  Yasunobu Iwasak  Masahiko Hayashi  Masahiro Hase 《Acta Meteorologica Sinica》1994,8(4):478-487

The results of two balloon soundings during the summer and autumn of 1993 from the Xianghe Observation Station are being utilized in a study of the temporal and spatial distribution of the atmospheric aerosols.The balloon,gondola,instrumentation and atmospheric conditions during the observation period are described.The temporal and spatial characteristics of aerosol concentration,size ratio,mixing ratio,and size distribution for both troposphere and strato-sphere are presented and analyzed.  相似文献