利用遥感与GIS分析珠江三角洲农田流失的空间分布规律及影响因素 --以东莞市为例

近年珠江三角洲出现了迅速的城市化的过程,大量的农田被推平作为非农业用地,其中有相当一部分的土地资源被不合理地浪费掉.分析这种土地利用变化的过程,可以为有效地利用土地资源提供规划依据.本文利用遥感与GIS相结合的方法,探讨了东莞市农田流失的时空分布规律.通过熵的计算,对快速的城市扩张过程进行了定量化的监测.并利用重力模型,研究造成这种现象的影响因素.研究发现,东莞市某些镇近年来的农田流失尤为严重.     

四种IHS变换用于SAR与TM影像复合的比较

本文采用四种典型的ＩＨＳ变换对同一地区的ＳＡＲ与ＴＭ影像进行了复合,并对复合影像作了定性和定量的分析。试验结果表明：用熵、联合熵和平均棍度这３个客观定量指标评价复合效果不仅比目视评价准确有效,而且提供了选择最佳ＩＨＳ变换用于复合的方法。     

边坡系统演化的开放度研究

边坡是一个由多个子系统组成的开放系统 ,开放是其发展、演化的前提与基础。为了研究边坡演化过程的开放性问题 ,本文提出了边坡系统演化的开放度概念及其理论表达式 ,讨论了边坡演化的开放度P的变化及其与熵流的关系 ,从理论上解释了边坡系统的二重性 ,建立了边坡系统开放度研究的初步理论框架 ,为研究边坡演化及滑坡防治提供了理论依据.     

Simultaneous modelling of multi-purpose/multi-stop activity patterns and quantities consumed

 Whereas for commuting travel there is a one-to-one correspondence between commuters and jobs, and for commodity flows a one-to-one correspondence between the size of orders and the shipping cost of the commodities, the situation is much more complex for retail/service travel. A typical shopper may make a single trip or multi-stop tour to buy/consume a quite diverse set of commodities/services at different locations in quite variable quantities. At the same time, the general pattern of the tour is clearly dependent on the activities and goods available at potential stops. These interdependencies have been alluded to in the literature, especially by spatial economists. However, until some preliminary work by the first author, there has been no attempt to formally include these interdependencies in a general model. This paper presents a framework for achieving this goal by developing an evolutionary set of models starting from the simplest forms available. From the above, it is clear that such interdependency models will inevitably have high dimensionality and combinatorial complexity. This rules out a simultaneous treatment of all the events using an individual choice approach. If an individual choice approach is to be applied in a tractable manner, the set of interdependent events needs to be segmented into several subsets, with simultaneity recognised within each subset, but a mere sequential progression occurring between subsets. In this paper, full event interdependencies are retained at the expense of modelling market segments of consumers rather than a sample of representative individuals. We couple the travel and consumption events in the only feasible way, by modelling the tours as discrete entities, in conjunction with the amount of each commodity consumed per stop on each such tour in terms of the continuous quantities of microeconomics. This is performed both under a budget/income constraint from microeconomics and a time budget constraint from time geography. The model considers both physical trips and tele-orders. Received: 14 August 2000 / Accepted: 6 October 2001     

玛纳斯地震前后地震活动信息熵及分维的动态变化

根据耗散结构理论及Mandelbort提出的分形几何学观点,研究了玛纳斯5.8级地震前后地震(M_s≥1.5)序列的时空分布特征、地震活动信息熵及分维的动态变化。发现玛纳斯5.8级地震前存在减熵和降维。认为,地震熵或分维可以定量描述地震时空分布变化过程,并量度变化过程从无序向有序的演化。     

Assessment of reliability in water distribution networks using entropy based measures

Entropy based expressions for measurement of reliability and redundancy have recently been reported. These measures approach assessment of the reliability of the distribution network from the intrinsic redundancy of the network layout. The paper extends earlier work on entropy functions by including a more explicit statement of the alternate paths available in the network and by recognizing that under certain circumstances, e.g., failure of some part of the network work, an outflow link from a node under normal working condition may become an inflow link to the same node. The measures are assessed by comparison with parameters measuring Nodal Pair Reliability and percentage of flow supplied at adequate pressure for a range of networks and link failure conditions in this networks. The entropy measures are shown to reflect changes in the network reliability, as measured by these two comparative parameters, very well.     

强震前后广义地震应变释放过程的丛集特征

利用基于小波变换的多重分形奇异谱估计方法,研究了部分强震前后地震活动广义应变.释放过程的多重分形特征。结果表明,晨中区附近- -定范围内地展活动广义应变释放过程具有多重分形特征,但多重分形维数谱随7变化复杂,在强震发生前多重分形维数谱没有明显的变化。广义地震应变释放过程的多重分形奇异谱形态和Hausdorff奇异指数范围能提供更多关于地屣活动过程的信息,特别当η取较大值时Hausdorff奇异指数范围在强晨前明显变窄。研究还表明深源地展和浅源地晨发生前广义应变释放过程多重分形特征存在明显不同。     

洪涝灾情快速反应的星载SAR与TM数据的融合处理

本文以1998年鄱阳湖地区发生洪涝灾害为研究实例,应用灾中的Radarsat-SAR和灾前的TM数据,以不规则三角网(TIN)方法实现了高精度几何配准。然后,通过波段相关性和信息熵值分析,选取最佳波段。最后,对不同融合模型得出的图像进行对比,得出结论:以灾中的SAR和灾前TM的一个近红外(TM5或TM7)以及一个可见光波段(TM3最佳),分别赋RGB色合成的图像效果很好,既能识别区分洪涝淹没的绝产区、土壤滞水减产区和未受灾区,并且操作简便,能满足洪涝灾情快速反应要求。     

华北型煤田煤层底板突水预测信息分析理论、方法及应用

在我国华北煤矿区,回采工作面煤层底板突水问题相当严重,困扰着煤矿经济效益的正常发挥。本文针对回采工作面煤层底板突水的特点,提出采用随机-信息方法解决其突水预报问题,建立了信息判据,并对大量的实例进行了验证,取得了满意的效果。      

基于熵权法的南水北调西线工程区生态环境综合评价

在遥感和地理信息系统软件支持下,提取并分析了参与研究区生态环境质量综合评价的6个参评因子:海拔高程、土地覆盖类型、植被指数、植被净初级生产力、年均温度、年降水量诸自然环境因子的现状。通过熵权法确定6个参评因子的权重值,建立研究区自然生态环境质量综合指标评价模型,并利用该模型对南水北调西线一期工程区的自然环境进行定量分析。