基于GIS的商业网点选址研究与实现   总被引：2，自引：0，他引：2  

刘娜  徐京华 《四川测绘》2005,28(2):78-81

利用平面／网络优化模型，综合权衡市区选址的基本费用及商业网点日常经营的成本，引入交通便利因子作为限制条件，并运用直接搜索的Dixon方法，加强了不确定性选址问题的约束条件，降低不确定性问题计算的复杂度，减少在选址问题实现中主观因素对选址结果的影响。最后以某区新建商业网点选址为例，详细分析了直接搜索算法应用的具体过程。  相似文献   

MODIS数据在乌鲁木齐地区植被景观动态监测中的应用   总被引：2，自引：0，他引：2  

李聪肖继东  宫恒瑞石玉 冯志敏 《沙漠与绿洲气象(新疆气象)》2005,28(3):27-29

根据EOS／MODIS卫星时次高覆盖面广的特征，选取从4．10月的MODIS晴空资料，对整个乌鲁木齐地区植被景观进行动态监测，利用植被指数最大合成法制作了每月植被指数专题图。为了能够结合物候更好地分析乌鲁木齐地区植被随季节变化趋势以及不同时期植被生长状况，我们还制作了植被景观专题图及其变化评价图。评价图的优势在于能直观地反映植被变化的趋势，并能将变化的程度数字化，还可以根据不同的评价图叠加DEM做相应的分析。为乌鲁木齐地区植被变化研究提供有效的依据。  相似文献   

2005年8月21日桂西大暴雨天气分析与降水模拟     

曾小团  邓海光  农孟松  张和稳 《气象研究与应用》2005,26(4):5-8

利用常规、红外云图、雷达资料对2005年8月21日发生在桂西的大暴雨天气过程进行诊断分析,发现造成桂西这次强降雨主要直接影响系统来自低层切变线、高空低槽和地面静止锋。低层切变线是引发此次强降水的主要系统。低层低涡是在桂西强降水发生后才逐渐发展起来的。采用非静力中尺度数值模式(MM 5)对这次大暴雨过程进行初步模拟试验,结果表明模式对这次强降水的雨带分布、暴雨中心强度及其位置的模拟也与实况较为接近。  相似文献   

大气污染物SO_x输送方程的尺度分析   总被引：5，自引：1，他引：5  

程新金  黄美元  安峻岭  王自发  徐华英  周玲  肖辉 《气象学报》2002,60(4):468-476

文中用量纲分析方法分析了控制大气污染物输送方程的动力学特性。提出了 6种反映大气污染物输送过程中各种动力、物理和化学过程相对重要性的动力学参数。并以硫氧化物为例进行了各参数量级大小分析 ,尤其对 3种起汇作用 (去除机理 )的机理 (化学转化、干沉降和湿清除 )在不同尺度大气污染过程中的作用进行了详细分析。结果表明 :在一般情况下 ,SO2 的气相化学作用小于干沉降和湿清除的作用 ;干沉降作用很依赖于模式最底层厚度的选取 ;在有降雨时湿清除作用一般较大。文中还对大气污染物SOx 输送方程各项特征量的量级作了分析对比 ,得出了控制不同尺度大气污染物输送过程的零级近似方程和一级近似方程 ,并指出了这些方程的基本特征  相似文献   

Calculation Of The Height Of The Stable Boundary Layer In Practical Applications     

Sergej Zilitinkevich  Alexander Baklanov 《Boundary-Layer Meteorology》2002,105(3):389-409

Currently used and newly proposed calculation techniques for the heightof the stable boundary layer (SBL), including the bulk-Richardson-numbermethod, diagnostic equations for the equilibrium SBL height, and a relaxation-typeprognostic equation, are discussed from the point of view of their physical basis andrelevance to experimental data. Among diagnostic equations, the best fit to data exhibits an advanced Ekman-layer height model derived recently with due regard to the role of the free-flow stability. Its extension to non-steady regimes provides a prognostic equation recommended for use in practical applications.  相似文献   

A scanning electron microscope study of the effects of dynamic recrystallization on lattice preferred orientation in olivine     

Kyung-Ho Lee  Zhenting Jiang  Shun-ichiro Karato   《Tectonophysics》2002,351(4)

Effects of dynamic recrystallization on lattice preferred orientation (LPO) in olivine were investigated through the combination of two SEM-based techniques, electron backscattered diffraction (EBSD) technique for crystallographic orientation measurement and backscattered electron imaging (BEI) for dislocation observation. Samples are experimentally deformed olivine aggregates in simple shear geometry. In the sample deformed at T=1473 K and high stresses (480 MPa), only incipient dynamic recrystallization is observed along grain-boundaries. Orientations of these small recrystallized grains are more random than that of relict grains, suggesting an important role of grain-boundary sliding at this stage of recrystallization. In the sample deformed at T=1573 K and low stress (160 MPa), dynamic recrystallization is nearly complete and the LPO is characterized by two [100] peaks. One peak is located at the orientation subparallel to the shear direction and is dominated by grains with high Schmid factor. The other occurs at high angles to the shear direction and is due to the contribution from grains with low Schmid factor. Grains with high Schmid factor tend to have higher dislocation densities than those with low Schmid factor. Based on these observations, we identify two mechanisms by which dynamic recrystallization affects LPO: (1) enhancement of grain-boundary sliding due to grain-size reduction, leading to the modification of LPO caused by the relaxation of constraint for deformation; (2) grain-boundary migration by which grains with lower dislocation densities grow at the expense of grains with higher dislocation densities. Based on the deformation mechanism maps and stress versus recrystallized grain-size relation, we suggest that the first mechanism always plays an important role whereas the second mechanism has an important effect only under limited conditions.  相似文献   

The eastern Tonale fault zone: a ‘natural laboratory’ for crystal plastic deformation of quartz over a temperature range from 250 to 700 °C     

Michael Stipp  Holger Stünitz  Rene Heilbronner  Stefan M. Schmid 《Journal of Structural Geology》2002,24(12)

Near the eastern end of the Tonale fault zone, a segment of the Periadriatic fault system in the Italian Alps, the Adamello intrusion produced a syn-kinematic contact aureole. A temperature gradient from 250 to 700 °C was determined across the Tonale fault zone using critical syn-kinematic mineral assemblages from the metasedimentary host rocks surrounding deformed quartz veins. Deformed quartz veins sampled along this temperature gradient display a transition from cataclasites to mylonites (frictional–viscous transition) at 280±30 °C. Within the mylonites, zones characterized by different dynamic recrystallization mechanisms were defined: Bulging recrystallization (BLG) was dominant between 280 and 400 °C, subgrain rotation recrystallization (SGR) in the 400–500 °C interval, and the transition to dominant grain boundary migration recrystallization (GBM) occurred at 500 °C. The microstructures associated with the three recrystallization mechanisms and the transitions between them can be correlated with experimentally derived dislocation creep regimes. Bulk texture X-ray goniometry and computer-automated analysis of preferred [c]-axis orientations of porphyroclasts and recrystallized grains are used to quantify textural differences that correspond to the observed microstructural changes. Within the BLG- and SGR zones, porphyroclasts show predominantly single [c]-axis maxima. At the transition from the SGR- to the GBM zone, the texture of recrystallized grains indicates a change from [c]-axis girdles, diagnostic of multiple slip systems, to a single maximum in Y. Within the GBM zone, above 630±30 °C, the textures also include submaxima, which are indicative of combined basal a- and prism [c] slip.  相似文献   

中原地区M≥6级地震后的减(增)震效应     

谢智  刘尧兴  胡凤英  王文旭  王志敏  谢健健 《地震研究》2002,25(2):149-154

通过对中原地区1500年－2000年所有19次M≥6级地震后空间图像的分析，初步认为M≥6级地震发生后平均63年内，在距原震中平均176km内无M≥5级地震发生，全部19次震例均呈现出内部减震效应，而在其外围出现地震增强的活动图像特征，增震效应对应率为72％。这种强震后的减（增）震效应，不仅对地震危险性分析，而且对1年尺度以上的地震趋势预测均有一定的意义。  相似文献   

Torsional vibrations of elastic foundation on saturated media     

Longzhu Chen  Guocai Wang   《Soil Dynamics and Earthquake Engineering》2002,22(3)

A comprehensive analytical solution is developed to examine the torsional vibration of an elastic foundation on a semi-infinite saturated elastic medium for the first time. First, the governing equations of saturated media are solved by use of Hankel transform techniques. Then, based on the assumption that the contact between the foundation and the half-space is perfectly bonded, this dynamic mixed boundary-value problem can lead to dual integral equations, which are further reduced to the standard Fredholm integral equations of the second kind and solved by numerical procedures. Numerical examples are given at the end of the paper. The numerical results indicate that the response of the elastic foundation strongly depends on the material and geometrical properties of both the saturated soil-foundation system and the load acting on the foundation. In most of the cases, the dynamic behavior of an elastic foundation on saturated media significantly differs from that of a rigid plate bearing on the elastic half-space.  相似文献   

The El Salvador earthquakes of January and February 2001: context, characteristics and implications for seismic risk     

J. J. Bommer  M. B. Benito  M. Ciudad-Real  A. Lemoine  M. A. Lpez-Menjívar  R. Madariaga  J. Mankelow  P. Mndez de Hasbun  W. Murphy  M. Nieto-Lovo  C. E. Rodríguez-Pineda  H. Rosa 《Soil Dynamics and Earthquake Engineering》2002,22(5)

The small Central American republic of El Salvador has experienced, on average, one destructive earthquake per decade during the last hundred years. The latest events occurred on 13 January and 13 February 2001, with magnitudes M_w 7.7 and 6.6, respectively. The two events, which were of different tectonic origin, follow the patterns of the seismicity of the region although neither event has a known precedent in the earthquake catalogue in terms of size and location. The earthquakes caused damage to thousands of traditionally built houses and triggered hundreds of landslides, which were the main causes of fatalities. The earthquakes have clearly demonstrated trends of increasing seismic risk in El Salvador due to rapid population expansion in areas of high shaking and landslide hazard, exacerbated by deforestation and uncontrolled urbanisation. The institutional mechanisms required for the control of land use and building practice are very weak and present a major obstacle to risk mitigation.  相似文献