An efficient method for single-facility location and path-connecting problems in a cell map

This article presents an efficient method for simultaneously finding both the Weber cell and optimal connective paths in a grid. As numerous barriers of arbitrary shape and weighted regions are distributed in the cell map of this research, the problem scenario is similar to working out a real-life facility location selection and path-routing problems in a geographical map. In this study, the Weber problem of finding a single-facility location from an accumulation cost table is generated by a grid wave propagation method (higher-geometry maze router). After finding the Weber point (cell), optimal connective paths with minimum total weighted cost are backtracked between the Weber location cell and the demand cells. This new computation algorithm with linear time and space complexity can be integrated as a spatial analytical function within GIS.     

Explicit versus implicit front advancing schemes for the simulation of hydraulic fracture growth

The proper computation of the time evolution of the fracture front is the main challenge of three-dimensional (3D) hydraulic fracture growth simulation. We discuss explicit and implicit variants of a hydraulic fracture propagation scheme based on a level set representation of the fracture. Such a scheme couples a finite discretization of the governing equations and the near-tip hydraulic fracture asymptotes. We benchmark the accuracy, robustness, and stability of these different front advancing schemes on a number of test cases. Our results indicate a large computational gain of the explicit scheme at the expense of a slightly less accurate solution (few percent less accuracy over few time steps) when crossing heterogeneities. The predictor corrector scheme combines at least an approximately 25% computational gain while retaining the stability and accuracy of the fully implicit version of the scheme in all cases.     

Model identification and parameter estimation of elastoplastic constitutive model by data assimilation using the particle filter

Data assimilation, using the particle filter and incorporating the soil‐water coupled finite element method, is applied to identify the yield function of the elastoplastic constitutive model and corresponding parameters based on the sequential measurements of hypothetical soil tests and an actual construction sequence. In the proposed framework of the inverse analysis, the unknowns are both the particular parameter within the exponential contractancy model, n_E, which parameterizes various shapes for the yield function of the competing constitutive models, including the original/the modified Cam‐Clay models and in‐between models and the parameters of the corresponding constitutive model. An appropriate set, consisting of the yield function of the constitutive model and the parameters of the constitutive model, can be simultaneously identified by the particle filter to describe the most suitable soil behavior. To examine the validity of the proposed procedure, hypothetical and actual measurements for the displacements of a soil specimen were obtained for consolidated and undrained tests through a synthetic FEM computation and for consolidated and drained tests, respectively. After examining the applicability of the proposed procedure to these test results, the present paper then focuses on the actual measured data, ie, the settlement behavior including the lateral deformation of the Kobe Airport Island constructed on reclaimed land.     

Blasius问题临界值β~＊的一个新上界

为了研究流体力学边界层理论中的Blasius问题临界值上界的性质,给出了Blasius问题的等价奇异积分方程,通过研究等价的奇异积分方程的正解来研究Blasius问题临界值β＊的上界.通过选用新的比较函数c（t）和g（β）来研究奇异积分方程在C[β,1]中解的存在性,证明所获得的正解是等价奇异积分方程的解,得到Blasius问题临界值的新上界β＊≤-0.1971,改进了最近的首次估计β＊〈-0.18773.     

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An inverse problem methodology to identify flow channels in fractured media using synthetic steady-state head and geometrical data

We present a methodology for identifying highly-localized flow channels embedded in a significantly less permeable medium using steady-state head and geometrical data. This situation is typical of fractured media where flows are often strongly channeled at the scales of interest (10 m–1 km). The objective is to identify both geometrical and hydraulic characteristics of the conducting structures. Channels are identified in decreasing order of importance by successive optimizations of an objective function. The identification strategy takes advantage of the hierarchical flow organization to restrict the dimension of the solution space of each individual optimization step. The characteristics of the secondary channels are strongly determined by the main flow channels. The latter are slightly modified by the secondary channels through the addition of a regularization term to the main channel characteristics in the objective function. As the objective function is strongly non-convex with numerous local minima, inversion is performed using a stochastic algorithm (simulated annealing). We assess the possibilities of the hierarchical identification strategy on simple synthetic steady-state flow configurations where hydraulic data are made up of 25 regularly spaced heads and of the boundary conditions. Those flow structures that are dominated by at most two simple channels can be identified with these head data only. Configurations comprising up to three complex and interconnected channels can still be identified with additional geometrical information including the distances of piezometers to their closest channel. The capabilities of the hierarchical identification strategy are limited to flow structures dominated by at most three equivalent flow channels. We finally discuss the perspectives of application of the method to transient-state data obtained on a more restricted number of piezometers.     

可编辑复杂线状符号库的设计与实现

针对GDI+绘制复杂线状符号存在符号不可编辑与遮挡等问题,设计了一种可编辑的复杂线状符号的组织方法,该方法将复杂线状符号分解为实线、虚线和点线三种基本单元,进而设计了基于这三种基本单元的复杂线状符号参数描述方法,解决了GDI+绘制复杂线状符号存在符号不可编辑与遮挡等问题。采用C#实现了可编辑线状符号库的设计与开发,建立了1:10 000地形图符号库。最后,对本文方法与GDI+方法的绘制效率进行了比较试验。试验表明本文方法不仅解决了GDI+绘制复杂线状符号存在符号不可编辑与遮挡等问题,并且绘制效率也明显优于GDI+方法。     

青岛市崂山区宅基地用地现状与对策

以青岛市崂山区3个街道的农村宅基地用地调研为基础,介绍崂山区农村宅基地用地现状,指出当前存在的问题,提出先行解决一部分住房困难村民的宅基地问题、加快编制报批村庄系列规划、强化执法监察、加大土地法律法规的宣传教育力度、积极推进农村建设用地整理等对策和建议。     

哈萨克斯坦跨界河流国际合作问题

哈萨克斯坦是中亚地区的“大国”,与四周比邻的国家均存在跨界水体联系,有44%的地表水来自邻国。跨界河流水资源开发利用与生态环境保护问题,是涉及国家政治、经济、安全、外交大局的重大战略问题。通过分析哈国地表水分布特点,简要回顾总结了与其邻国在跨界河流方面的合作情况;对哈国所担忧的水安全问题及采取的主要对策,进行了深入剖析,并就跨界河流管理未来的合作路径、跨界河流利用未来的分水原则、哈俄跨界河流水污染未来的解决途径、中亚国家间解决咸海危机的前提条件等问题,进行了分析讨论;指出对共享水资源的管理既可以成为中亚地区和平的力量,也可能成为冲突的因素,管理这种相互依存的资源是当今国际社会面临的一项关系人类发展的重大挑战。研究哈萨克斯坦跨界河流国际合作及其对核心利益问题的观点、认识、所采取的不同策略,对于处理好中哈跨界河流问题具有积极现实意义。     

层状大地频率域长导线源激发的电磁场

采用Fourier变换法从Maxwell方程组出发,导出了层状大地模型上接地长导线源激发的电磁场表达式。结果表明：接地长导线源实际上是2个接地电极和线电流源构成的一个组合源;其电磁场表达式表明平行于长导线方向的电场分量为2个接地电极激发的平行于长导线方向的电场分量和线电流激发的电场的叠加,垂直于长导线方向的电场分量和电场的垂直分量均是2个接地电极激发的;平行于长导线方向的磁场分量由2个接地电极所激发,而垂直于长导线方向的磁场分量为2个接地电极激发的垂直于长导线方向的磁场分量和线电流激发的磁场的叠加,磁场的垂直分量为线电流源所激发。进一步的结果分析表明,在均匀半空间上、大收发距时,2个接地电极激发的平行于长导线方向的电场分量和线电流激发的电场分量是相等的,2个接地电极激发的垂直于长导线方向的磁场分量和线电流激发的磁场分量是相等的,且它们的振幅与2个电极之间的距离成正比。