The wet-dry changes in recent 40 years in taklimakan area   总被引：6，自引：0，他引：6  

袁玉江  李江风  叶玮 《中国地理科学(英文版)》1999,9(1):57-62

IINTRODUCTIONAlongwiththePetroleumexploitationofTarimBasin,consideringaboutwaterresources,peoplepaidmuchattentiontothestudyofthemodernclimatechangeinTaklimakanarea.SomePeoplehaddonemanalySeSwiththemeteorologicaldatainthearea(Yang,1992;Jietal.,1992;Zheng,1991;Xue,1989;Li,1989;Wenetal.,1988).BasedontheO~ionaldstaofprecipitationinrecent40years,thisPaperCarefullyanalyZedthewet-drychangeinrecentseveraldeCadesinTaklilnakanareaanditsneighdringareas(thenorthernXinjiang,QinghaiandGansuPro…  相似文献   

Regional effects by the construction of Suzhou Industry Garden     

陆玉麒  佘之祥 《中国地理科学(英文版)》1999,9(4):342-349

１　ＡＤＶＡＮＣＩＮＧＯＦＴＨＥＱＵＥＳＴＩＯＮＡＮＤＣＯＮＳＴＲＵＣＴＩＯＮＢＡＣＫＧＲＯＵＮＤＯＦＳＵＺＨＯＵＩＮＤＵＳＴＲＹＧＡＲＤＥＮＰｅｒｒｏｘｇａｖｅｓｐｅｃｉａｌａｔｔｅｎｔｉｏｎｔｏｔｈｅｅｆｆｅｃｔｏｆｉｍｐｏｒｔａｎｔｉｔｅｍｓａｎｄｃｏｎｓｔｒｕｃｔｉｏｎｏｆｉｎｆｒａｓｔｒｕｃｔｕｒｅｗｈｅｎｈｅｄｉｓｃｕｓｓｅｄｔｈｅｐｒｏｄｕｃｔｉｏｎｏｆｇｒｏｗｔｈｐｏｌｅ（Ｌｉ,１９８８）．Ｌｏｔｓｏｆｄｏｍｅｓｔｉｃｓｃｈｏｌａｒｓｈａｖｅａｌｓｏｐｒｏｂｅｄｉｎｔｏｔｈｉ…  相似文献   

辽南金矿集中区卫星图像构造解译及构造控矿模型探讨   总被引：2，自引：0，他引：2  

吕贻峰  李江风  秦松贤 《国土资源遥感》1998,9(4):43-49

辽南地区是我国最重要的五大金矿床集中区之一,大、中、小型矿床、矿点众多,矿床类型复杂,控矿因素多样。与国内外大多数金矿一样,在诸多控矿因素中,构造变形因素最为重要,而且有其自身的变形特点和特殊的控矿类型。本文旨在着重讨论辽南这一特定的金矿集中产出地所具有的构造控矿特征和构造控矿模型,为研究大型金矿区或金矿群的形成条件提供借鉴。  相似文献   

硅碳双键稳定性的CNDO/2法研究     

佘敬曾  高新生 《中国海洋大学学报(自然科学版)》1988,(3)

本文用CNDO/2法研究了硅碳双键Si=C不稳定的原因。通过分析SiH_2CH_2的烷基和苯基取代物的计算结果,对有大基因连接硅碳双键的化合物之所以能稳定存在做了合理的说明。  相似文献   

海水表面张力的研究

──海水表面张力同温度和实用盐度之间的经验关系     

陈国华  佘敬曾  郭玲  张力军 《海洋与湖沼》1994,25(3):306-311

用最大泡压法测定大洋海水及其被纯水稀释的海水温度在１５－３５℃，盐度５－３５的表面张力，所得数据经计算机统计处理得出海水表面张力同温度和盐度之间的经验公式：σｓｔ＝７５．５９＋０．０２１３５２ｓ－０．１３４７６ｔ－０．０００２９５２９ｓｔ在分别恒定盐度、温度度时，海水表面张力与温度、盐度有很的线性关系；其温度系数和盐度系数均非常数，温度系数随盐度增加绝对值增大，而其盐度系数随温度升高而变小。  相似文献   

Rendering 2D Lines on 3D Terrain Model with Optimization in Visual Quality and Running Performance          下载免费PDF全文

Jiangfeng She  Xin Tan  Xingchen Guo  Junzhong Tan  Jianlong Liu 《Transactions in GIS》2017,21(1):169-185

With the gradual shift from 2D maps to a 3D virtual environment, various visual artifacts were generated by overlaying 2D map symbols on 3D terrain models. This work proposes a novel screen‐based method for rendering 2D vector lines with the accuracy of more than one pixel on the screen in real time. First, screen pixels are inversely projected onto a 3D terrain surface, and then onto the 2D vector plane. Next, these pixels are classified into three categories in terms of their intersection situation with the 2D lines. After that, a multiple sampling process is applied to the pixels that intersect with the 2D lines in order to eliminate visual artifacts, such as intermittence and aliasing (in pixel scale). Finally, a suitable point‐in‐polygon judgment is implemented to color each sample point quickly. The algorithm is realized in a heterogeneously parallel model so that the performance is improved and becomes acceptable.  相似文献   

A new,high-resolution geoid for Canada and part of the U.S. by the 1D-FFT method     

Michael G. Sideris  Bin Bin She 《Journal of Geodesy》1995,69(2):92-108

A new, high-resolution and high-precision geoid has been computed for the whole of Canada and part of the U.S., ranging from 35°N to about 90°N in latitude and 210°E to 320°E in longitude. The OSU91A geopotential model complete to degree and order 360 was combined with a 5 × 5 mean gravity anomaly grid and 1km × 1km topographical information to generate the geoid file. The remove-restore technique was adopted for the computation of terrain effects by Helmert's condensation reduction. The contribution of the local gravity data to the geoid was computed strictly by the 1D-FFT technique, which allows for the evaluation of the discrete spherical Stokes integral without any approximation, parallel by parallel. The indirect effects of up to second order were considered. The internal precision of the geoid, i.e. the contribution of the gravity data and the model coefficients noise, was also evaluated through error propagation by FFT. In a relative sense, these errors seem to agree quite well with the external errors and show clearly the weak areas of the geoid which are mostly due to insufficient gravity data coverage. Comparison of the gravimetric geoid with the GPS/levelling-derived geoidal heights of eight local GPS networks with a total of about 900 stations shows that the absolute agreement with respect to the GPS/levelling datum is generally better than 10 cm RMS and the relative agreement ranges, in most cases, from 4 to 1 ppm over short distances of about 20 to 100km, 1 to 0.5 ppm over distances of about 100 to 200 km, and 0.5 to 0.1 ppm for baselines of 200 to over 1000 km. Other existing geoids, such as UNB90, GEOID90 and GSD91, were also included in the comparison, showing that the new geoid achieves the best agreement with the GPS/levelling data.Presented at theIAG General Meeting, Beijing, P.R. China, Aug. 6–13, 1993  相似文献   

青岛城市环境地理信息系统(UEGIS)的设计与实现     

王卫平  王东生  佘宗莲  陈宗团  贾永刚 《中国海洋大学学报(自然科学版)》2003,33(4):587-594

本文以青岛城市环境地理信息系统为例 ,利用 GIS技术论述了地理信息系统在环境管理中的应用 ,对系统软件的设计与实现作了介绍和分析 ,着重论述了系统的技术关键和解决方案。说明了利用 GIS技术给环境管理工作带来的便利 ,及对环境地理信息系统的发展前景作了展望。  相似文献   

Effect of Three Gorges Dam on Poyang Lake water level at daily scale based on machine learning   总被引：1，自引：1，他引：0  

HUANG Sheng  XIA Jun  ZENG Sidong  WANG Yueling  SHE Dunxian 《地理学报(英文版)》2021,31(11):1598-1614

Lake water level is an essential indicator of environmental changes caused by natural and human factors. The water level of Poyang Lake, the largest freshwater lake in China,has exhibited a dramatic variation for the past few years, especially after the completion of the Three Gorges Dam(TGD). However, there is a lack of more accurate assessment of the effect of the TGD on the Poyang Lake water level(PLWL) at finer temporal scales(e.g., the daily scale). Here, we used three machine learning models, namely, an Artificial Neural Network(ANN), a Nonlinear Autoregressive model with eXogenous input(NARX), and a Gated Recurrent Unit(GRU), to simulate the daily lake level during 2003–2016. We found that machine learning models with historical memory(i.e., the GRU model) are more suitable for simulating the PLWL under the influence of the TGD. The GRU-based results show that the lake level is significantly affected by the TGD regulation in the different operation stages and in different periods. Although the TGD has had a slight but not very significant impact on the yearly decline of the PLWL, the blocking or releasing of water at the TGD at certain moments has caused large changes in the lake level. This machine-learning-based study sheds light on the interactions between Poyang Lake and the Yangtze River regulated by the TGD.  相似文献   

Synthesis of Mullite from High-alumina Fly Ash: a Case from the Jungar Power Plant in Inner Mongolia, Northern China     

CHEN Jiangfeng  SHAO Longyi  LU Jing 《《地质学报》英文版》2008,82(1):99-104

In this paper, an experimental study was conducted in order to test the feasibility of sintering mullite directly from the high-alumina fly ash, without adding any extra material. The results show that the mullite contents in most sintered samples are over 70%. The samples sintered from the beneficiated fly ash have a higher content of mullite than those from the as-received fly ash under the same synthetic conditions. To obtain an equal amount of mullite, a higher sintering temperature is needed for the beneficiated fly ash than for the as-received fly ash. Considering the physical properties of sintered mullite, the favorable sintering temperature is 1400℃ for the as-received fly ash and 1500℃ for the beneficiated fly ash. A higher sintering temperature and a shorter holding time are profitable to sintering mullite. The orthogonal test confirmed that the dominant factor affecting mullite synthesis is sintering temperature, and that the most profitable matching conditions are 200 MPa-1500℃-3 h for the as-received fly ash and 200 MPa-1500 ℃-4 h for the beneficiated fly ash.  相似文献