A parallel algorithm for coverage optimization on multi-core architectures     

Ran Wei  Alan T. Murray 《International journal of geographical information science》2016,30(3):432-450

Location siting is an important part of service provision, with much potential to impact operational efficiency, safety, security, system reliability, etc. A class of location models seeks to optimize coverage of demand for service that is continuously distributed across space. Decision-making and planning contexts include police/fire resource allocation for a community, siting cellular towers to support cell phone signal transmission, locating emergency warning sirens to alert the public of severe weather and other related dangers, and many others as well. When facilities can be sited anywhere in continuous space to provide coverage to an entire region, this is a very computationally challenging problem to solve because potential demand for service is everywhere and there are an infinite number of potential facility sites to consider. This article develops a new parallel solution approach for this location coverage optimization problem through an iterative bounding scheme on multi-core architectures. The developed approach is applied to site emergency warning sirens in Dublin, Ohio, and fire stations in Elk Grove, California. Results demonstrate the effectiveness and efficiency of the proposed approach, enabling real-time analysis and planning. This work illustrates that the integration of cyberinfrastructure can significantly improve computational efficiency in solving challenging spatial optimization problems, fitting the themes of this special issue: cyberinfrastructure, GIS, and spatial optimization.  相似文献   

A new model of edge-to-edge contact for three dimensional discontinuous deformation analysis     

M. Mousakhani  A. Jafari 《Geomechanics and Geoengineering》2016,11(2):135-148

A robust contact theory can be regarded as key to three dimensional discontinuous deformation analyses (3D-DDA). Not only must this theory provide an efficient algorithm to judge the type and location of contacts but also it must be able to present comprehensive formulations for every kind of contact (open, sliding and locked contact). There are six types of contact in three dimensional discontinuous deformation analyses (vertex-to-vertex, vertex-to-edge, vertex-to-face, edge-to-edge, edge-to-face and face-to-face) that can be converted to vertex-to-face and edge-to-edge contacts. This paper presents a new model of edge-to-edge contact to three dimensional discontinuous deformation analyses (3D-DDA). This new model considers both kinds of edge-to-edge contact (cross-over and parallel edge-to-edge contact) and presents a criterion for inter-penetration. Sub matrices of normal and shear spring and friction force are derived by geometrical analysis and penalty method. This new model is implemented in a 3D-DDA computer programme, and the example results demonstrate the validity of the model.  相似文献   

Development of A Depth-Integrated Longshore Current Model with Unstructured Grids     

陈超  张庆河 《海洋工程》2016,(5):718-732

A depth-integrated model for simulating wave-induced longshore current was developed with unstructured grids. Effects of surface roller and horizontal mixing under combined waves and currents were incorporated in the numerical model. Recommended values of model coefficients were also proposed based on sensitivity analysis. Field observations and three series of laboratory measurements including two cases conducted on the plane beach and one implemented on the ideal inlet were employed to examine the predictive capability of this model. For the field case and laboratory cases conducted on the plane beach, numerical results were compared favorably with the measured data. For the case with an ideal inlet, simulated circulation pattern is supposed to be reasonable although some deviations between numerical results and measured data still can be detected.  相似文献   

Foundations of petroleum prediction based on the activation of geochemical processes by direct current     

V.Yu. Shigaev 《Russian Geology and Geophysics》2018,59(11):1508-1513

Petroleum prediction in local objects and the applicability of geologic environment parameters in this regard are considered. The proposed guidelines for petroleum potential prediction are based on the analysis of the distribution of typomorphic epigenetic multivalent elements loosely fixed in rocks before and after electric current treatment. The advantage of geoelectrochemical methods providing data on the chemical composition of above-productive deposits is demonstrated.  相似文献   

河流景观生态学的发展与当前核心议题          下载免费PDF全文

薛兴华  钱华 《水科学进展》2018,29(6):887-897

河流景观生态学已成为河流科学研究与应用的新范式,但国内研究还颇为不足。从河流景观生态学发展的逻辑必然性、主要进程、基本内容与重要理论等方面进行了总结。结果显示,多尺度跨学科整体论河流认识要求和景观尺度上处理河流问题的实践需求共同推动河流景观生态学的迅速发展,其中心议题是河流物理景观系统与生物系统在不同等级尺度上的结构、格局与功能过程,尤其重视物理景观与不同等级生物系统的相互作用关系,对河流景观多尺度等级性、高动态性和有向性等突出性质的认识已取得重要理论发展。指出当前面临5个方面的核心议题亟需取得突破:改进和统一河流景观分类系统、河流景观跨尺度研究、河流景观方法对经典河流生态理论的再认识、河流景观机理与模拟、河流景观对气候变化与区域土地利用/覆被变化的响应研究。  相似文献   

我国干热岩资源分布及勘探:进展与启示   总被引：3，自引：0，他引：3  

蔺文静  王贵玲  邵景力  甘浩男  谭现锋 《地质学报》2021,95(5):1366-1381

干热岩是地热资源的重要赋存形式之一,是未来地热开发的主攻方向.我国干热岩勘查工作近年来进展迅速,先后在不同地区发现了优质的干热岩资源,取得了我国干热岩资源勘查突破,但同时也存在不少勘查失败的案例.本文在分析高放射性产热型、沉积盆地型、近代火山型和强烈构造活动带型等四种类型干热岩成因模式的基础上,结合我国的地质构造背景、地热地质条件,对未来我国干热岩资源重点勘查方向及靶区进行了论述,并重点针对目前不同类型区干热岩资源勘探工程进行了梳理,简要分析了不同勘探区的选址依据、勘探过程、地温场分布及特征、前景预测等,并初步进行了经验总结,希望对我国未来干热岩资源勘查及开发工作起到借鉴作用.  相似文献   

岩石蠕变声发射特性研究现状与展望          下载免费PDF全文

李玉山  席伟  张诏飞  董堃 《甘肃地质》2021,(2):66-69

蠕变是岩石一种重要的力学特性,与工程的长期安全稳定和安全密切相关。声发射技术作为一种无损检测手段,被广泛应用于岩石变形破坏研究领域。本文阐述了近年来基于声发射技术开展岩石蠕变特性方面的研究进展,主要包括不同岩性、加载方式、应力水平下岩石蠕变声发射特性,岩石蠕变破坏声发射前兆特征。在此基础上,提出了几点今后需要进一步深入研究的问题。  相似文献   

Investigation of highly efficient algorithms for solving linear equations in the discontinuous deformation analysis method          下载免费PDF全文

Xiaodong Fu  Qian Sheng  Yonghui Zhang  Jian Chen 《国际地质力学数值与分析法杂志》2016,40(4):469-486

Large‐scale engineering computing using the discontinuous deformation analysis (DDA) method is time‐consuming, which hinders the application of the DDA method. The simulation result of a typical numerical example indicates that the linear equation solver is a key factor that affects the efficiency of the DDA method. In this paper, highly efficient algorithms for solving linear equations are investigated, and two modifications of the DDA programme are presented. The first modification is a linear equation solver with high efficiency. The block Jacobi (BJ) iterative method and the block conjugate gradient with Jacobi pre‐processing (Jacobi‐PCG) iterative method are introduced, and the key operations are detailed, including the matrix‐vector product and the diagonal matrix inversion. Another modification consists of a parallel linear equation solver, which is separately constructed based on the multi‐thread and CPU‐GPU heterogeneous platforms with OpenMP and CUDA, respectively. The simulation results from several numerical examples using the modified DDA programme demonstrate that the Jacobi‐PCG is a better iterative method for large‐scale engineering computing and that adoptive parallel strategies can greatly enhance computational efficiency. Copyright © 2015 John Wiley & Sons, Ltd.  相似文献   

Effects of wave–current interaction on the current profile     

Maitane Olabarrieta  Raul Medina  Sonia Castanedo 《Coastal Engineering》2010

Wave–current laboratory experiments have shown that the logarithmic current profile observed in pure current flows is modified due to the presence of waves. When waves propagate opposite the current, an increase in the current intensity is achieved near the mean water level, while a reduction is obtained for following waves and currents. With the aim of analyzing these nonlinear effects along the whole water column, an Eulerian wave–current model is presented. In contrast to previously presented wave–current models, the present is able to include the variation of the free surface elevation due to the wave motion and the effect of a non hydrostatic pressure field. Therefore it does not restrict its application to waves in shallow waters. Moreover, the model is able to simulate all the possible angles between waves and currents.  相似文献   

聚合物驱组合段塞分注实验研究     

李宜强  林丽华  梁双庆 《海洋地质译丛》2010,(1):85-89

萨尔图油田南二区东部140号断层以东地区葡11—4油层，以多段多韵律和正韵律沉积为主，平均孔隙度30．0％，平均空气渗透率1980×10^-3μm2。水驱结束时该油层平均含水92％，采出程度39．5％。计划对该区块实施聚合物驱开采。以往经验认为，组合段塞调整注聚技术能够有效改善流度控制作用。然而对组合注入情况下如何进一步提高驱油效果、注入井分注时机、层段注入强度对开发效果有何影响却很少探讨。通过室内驱油实验，在聚驱的组合段塞注入不同时机（水驱空白阶段、含水下降阶段、含水稳定阶段、含水回升阶段）下调整注入强度实施分注以及在含水回升分注基础上进一步调整注入强度，同时对比不分注实验，评价各方案驱油效果。实验表明：不实施分注时聚驱采收率在水驱基础上提高了19．07个百分点，而组合段塞注入时实施分注均能够在不分注基础上进一步提高驱油效果；空白水驱时实施分注采收率提高幅度最大，为26．55个百分点；随着分注时机的滞后采收率提高幅度增加值依次递减，分注时机越早越好。  相似文献