A contrast of two typical LUCC processes and their driving forces in oases of arid areas: A case study of Sangong River Watershed at the northern foot of Tianshan Mountains

Aerial photographs taken in 1978 and 1987, Landsat TM images in 1998 as well as soil, hydrology and socio-economic data for the oases in Sangong River Watershed were processed by Remote Sensing (RS) and Geographic Information System (GIS). There are two typical agricultural land uses in oases, Farm-based Land Use with large-scale intensified agricultural activities (FLU) and Household Responsibility-based Land Use with small-scale activities (HRLU). The Index Model of Land Use/Land Cover Change (LUCC), Weighted Index Sum (WIS) and logistic stepwise regression model were established to contrast the two typical LUCC processes and their driving forces. The land use patterns were dominated by cropland and grassland for the entire region, and cropland, residential and industrial land were increasing stably. In the HRLU areas, woodland and grassland declined dramatically, but in the FLU areas, grassland decreased only by 12.0%, whereas woodland increased by 13.7%. LUCC was stronger in the earlier stage (1978–1987) than in the later stage (1987–1998) for the entire region. LUCC was more intense in the HRLU areas than in the FLU areas during the entire period (1978–1998). Policy was a key factor in the land use change, and water resources were a precondition in land use. Under the control of policy and water resources, the main human driving factors included population and economy, and the main natural restrictions were soil fertility and groundwater depth. Human driving factors controlled the land change in the HRLU areas, but natural restriction factors dominated in the FLU areas. In the mean time, intensification of LUCC in the region had some spatiotemporal implications with a fluctuation of impact factors.     

Robust H∞ control for aseismic structures with uncertainties in model parameters

This paper presents a robust H∞ output feedback control approach for structural systems with uncertainties in model parameters by using available acceleration measurements and proposes conditions for the existence of such a robust output feedback controller. The uncertainties of structural stiffness, damping and mass parameters are assumed to be norm-bounded. The proposed control approach is formulated within the framework of linear matrix inequalities, for which existing convex optimization techniques, such as the LMI toolbox in MATLAB, can be used effectively and conveniently. To illustrate the effectiveness of the proposed robust H∞ strategy, a six-story building was subjected both to the 1940 El Centro earthquake record and to a suddenly applied Kanai-Tajimi filtered white noise random excitation. The results show that the proposed robust H∞ controller provides satisfactory results with or without variation of the structural stiffness, damping and mass parameters.     

基于进化方向遗传算法的四维变分资料同化方法

数值天气预报模式初始时刻要素场的变分同化问题是一个非线性最优化问题。利用进化方向遗传算法（EDGA）求解该最优化问题，并对理想初始场作数值模拟，结果表明模拟的效果较好。     

广东沿海强东北季风的气候统计特征

通过对1988－1997年冷空气造成的广东沿海强东北季风过程的气候统计分析，发现广东的强东北季风有明显的月分布规律，而年际变化有逐渐减少的趋势；强东北季风与地面因子相关程度较高，而与850hPa要素相关性较低；同时发现地面冷高压中心位置聚合度较高，但不同月份、不同时次，其中心位置有明显差异。     

分区统计地图上符号的视觉搜寻和认知工效研究

根据某地区的分区统计数据和有关图集，总结设计出4种方案的分区统计地图，在自行编制的认知测试软件上进行了目标搜寻测试，结果表明，在分区统计地图上搜寻目标时，视觉系统运用了平行加工策略和序列加工策略，4个方案的目标搜寻平均反应时间和正确率受到这两种策略的影响。     

基于自适应四叉树分割的遥感图像压缩算法

遥感图像具有不同于一般图像的特点,针对遥感图像对压缩算法的特殊要求,提出了自适应四叉树分割算法实现图像的分块,以各像块的均值近似表示该像块的灰度值,从而以尺量少的数值获得对原始图像的最佳逼近,再对辐近误差进行自适应分割和基于像块方差的自适应量化,最后对各分量进行Huffman编码.实验表明,本算法能表现出良好的实用性能,比JPEG算法更适用于遥感图像的压缩.     

矿区构造变形岩相形迹填图、矿化趋势度的实测及其地质找矿——以胶东玲珑金矿田阜山金矿区为例

以玲珑金矿田阜山金矿区为实测地区，研究了胶东构造岩浆岩浆活化区玲珑-焦家式金矿的矿源岩系，对2km^2内矿源岩的构造变形岩相形变进行1/2000填图。在此基础上，提出矿化趋势度（MTD）的概念并完成阜山金矿区矿化趋势度的分布图。矿化趋势度的概念及其填图研究方法对于探讨将成矿模型转化为找矿模型、逐步建立更具体量化的找矿预测实测方法有重要的参考价值和应用前景。     

济阳坳陷四扣洼陷泥质岩裂缝储层预测研究

通过对济阳坳陷四扣洼陷及郭局子地区泥质岩储层的裂缝类型、识别特征进行的研究，认为影响本区裂缝发育程度的因素是区域构造应力及构造部位、岩性、岩相、岩层厚度、埋深及地层压力。并在此基础上建立了地质模型、力学模型和数学模型，运用三维有限元方法对四扣洼陷构造裂缝储层的分布进行了预测。通过预测，提出了研究区裂缝发育在平面上具有不均匀性、连片性差、与断层关系密切的特点，进一步指出了罗42－罗48井区等8个区带为裂缝发育的地区。这项研究不仅对研究区泥岩油气勘探，而且对济阳坳陷及类似地区的泥岩油气勘探有重要指导和启示意义。     

水资源中氯代烃污染物的去除方法

随着工业化的发展。氯代有机溶剂使用越来越广泛。并且难于去除。在20世纪90年代初期，人们就已认识到用Fe^0恢复污染的地下水的潜力。国外正在研究帮使用扔几种还原挥发性氯代烃的还原反应介质，尤其要提高的是双金属反应系统，反应速度快，而且脱Cl中国难解产物少，目前国也只停留在实验室研究阶段，个别做了地上反应器的验证实验，它的脱Cl机理、介质钝化和完全脱Cl问题还有待于进一步研究。     

混流式转轮中流场的大涡模拟

建立了基于微可压缩流体理论的相对运动的大涡模拟方法,并对混流式转轮流场进行了三维非恒定粘性数值模拟,计算方法采用了有限体积法和预测-校正方法,对固体边壁的处理使用了“壁函数”法。得到了混流式转轮的三维速度场和压力分布,与k-ε模型计算结果进行比较表明,所建立的相对运动的大涡模拟方法对转轮性能预测更加精确、合理,对转轮改型设计具有十分重要的参考价值。