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941.
Techniques developed for structural identification of a structural model are typically based on information regarding the response and the forcing actions. However, in some situations it can be necessary, or simply useful, to refer only to the measured responses. In this paper we describe a technique suitable for identifying the modal model of a spatial frame in the frequency domain when the seismic input is unknown both in time contents and direction. In some previous theoretical works we established that this identification problem has a unique solution when at least three time‐history responses are known. Here numerical techniques are developed which allow the evaluation of the modal quantities in practice. Numerical applications are carried out on plane and spatial framed structures by using a modal model which may be complete, including all the structure's modes, or incomplete, including only the lowest modes. In most cases the obtained results are satisfactory. Copyright © 2005 John Wiley & Sons, Ltd. 相似文献
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943.
Assessment of Discharge through a Dike Breach and Simulation of Flood Wave Propagation 总被引:2,自引:0,他引:2
This paper presents a simple and fast method to calculate flow through a dike breach. The approach was based on two-dimensional
numerical simulations of idealized dike breakages at straight river-sections. As a result, computation of discharge through
a breach can be achieved by use of the new developed formula (denoted as dike break formula). Furthermore, a methodology that combines one-dimensional hydrodynamic modelling, the dike break formula and a simple GIS-based
method to estimate inundation areas is described. This fast and easy-to-handle tool can be utilized for near real-time forecasting
or evacuation decisions. Detailed predictions were made for a number of flood and dike break scenarios at the River Rhine
to prove the accuracy of the new method compared with two-dimensional numerical models. 相似文献
944.
导水裂隙带高度研究方法概述 总被引:2,自引:0,他引:2
导水裂隙带高度的确定是水下采煤工作之重点,目前并没有一个完全可以精确确定的方法。主要的研究方法有经验公式法、物理模拟、数值模拟和现场实测。单靠其中的一种也不能确定,将几种方法相互结合则是准确得到导水裂隙带高度计算方法的重要途径。 相似文献
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软土地质条件下的既有建筑物地基基础加固或改造面临诸多复杂条件,施工安全和周边环境保护尤为重要,为此提出微型钢管--旋喷复合桩工艺。通过开展微型钢管--旋喷复合桩各项承载力现场试验研究,获取钢管桩应变数据,分析其承载特性及传力机制,总结提出微型钢管--旋喷复合桩承载力设计计算公式,为开展工程应用提供理论依据。 相似文献
949.
以亚热带季风区的典型流域——闽江流域为研究区域,根据Penman-Monteith(P-M)公式和双作物系数法,计算了闽江流域内8个气象观测站点的实际蒸散量,并评估了GLDAS-Noah实际蒸散产品在闽江流域的适用性。在此基础上,基于GLDAS-Noah实际蒸散发数据,解读了2000—2019年闽江流域的实际蒸散量的变化特征。结果表明:① GLDAS-Noah实际蒸散发数据在闽江流域的适用性较好(R2>0.9,NSE>0.8);② 2000年以来闽江流域的实际蒸散发呈增加趋势(3.86 mm/a,P < 0.01),且存在显著的季节差异,表现为冬季和春季的增加速率要大于夏季和秋季;③ 闽江流域冬季和春季蒸散发增加与气温密切相关,冬季蒸散发与冬季气温呈微弱正相关( R = 0.27),春季蒸散发的增加与春季升温密切相关(R = 0.79)。 相似文献
950.
Dieudonné Tsatcha Éric Saux Christophe Claramunt 《International journal of geographical information science》2014,28(7):1355-1377
Route planning is an important problem for many real-time applications in open and complex environments. The maritime domain is a relevant example of such environments where dynamic phenomena and navigation constraints generate difficult route finding problems. This paper develops a spatial data structure that supports the search for an optimal route between two locations while minimizing a cost function. Although various search algorithms have been proposed so far (e.g. breadth-first search, bidirectional breadth-first search, Dijkstra’s algorithm, A*, etc.), this approach provides a bidirectional dynamic routing algorithm which is based on hexagonal meshes and an iterative deepening A* (IDA*) algorithm, and a front to front strategy using a dynamic graph that facilitates data accessibility. The whole approach is applied to the context of maritime navigation, taking into account navigation hazards and restricted areas. The algorithm developed searches for optimal routes while minimizing distance and computational time. 相似文献