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61.
In order to investigate surf zone hydrodynamics through two-dimensional numerical simulations of nearshore circulation under random wave environment, a nearshore circulation model, SHORECIRC, and a random wave model, SWAN, were combined and utilized. Using this combined model, a numerical simulation of the October 2, 1997 SandyDuck field experiment was performed. For this simulation, field topography and an input offshore spectrum were constructed using observed data sets synchronized with the experiment. The wave-breaking model in SWAN was modified by using breaker parameters varied according to bottom slope. The simulation results were compared with the experimental data, which revealed a well-developed longshore current, as well as with results using other combinations which were SHORECIRC and its original monochromatic wave-driver, and SHORECIRC and the default of SWAN. The results from the novel combined model agreed well with the experimental data. The results of the present simulation also indicate that alongshore field topography influences shear fluctuation of longshore currents. 相似文献
62.
The numerical investigation of random wave slamming on superstructures of marine structures in the splash zone is presented in this paper. The impact pressures on the underside of the structure are computed based on the improved volume of fluid method (VOF). The governing equations are Reynolds time-averaged equations and the two equation k– model. The third order upwind difference scheme is applied to the convection term to reduce the effect of numerical viscosity. The numerical wave flume with random wave-maker suitable for VOF is established. Appropriate moving contact-line boundary conditions are introduced to the model wave in contact with and separated from the underside of structure. Parametric studies have been carried out for different incident waves, structure dimensions and structure clearance. The numerical results are verified by the experimental results. 相似文献
63.
64.
The shape optimization of the 2-dimensional wing in ground effect (WIG) has been performed by the integration of CFD (computational fluid dynamics) and MOGA (multi-objective genetic algorithm). Because of the trade-off between the aerodynamic forces and the height stability, it is difficult to satisfy the design requirements of efficiency and stability at the same time. In this study, the lift coefficient, the lift-drag ratio and the static height stability are chosen as the objective functions to obtain the optimal wing profiles of a WIG craft. An NACA0015 airfoil is used for the baseline model; the aerodynamic characteristics of the base model are compared with that of the optimal solutions. The profile of the airfoil is constructed by four Bezier curves with fourteen control points resulting in the eighteen coordinates, which are adopted as the design variables. The optimal solutions of the multi-objective optimization are not unique but a set of the non-dominated optima: the Pareto frontiers or a Pareto set. As the results of the multi-objective optimization, the forty Pareto optima, which include high-lift, high-efficiency, and more stable airfoils on the edge of the 3-dimensional objective space, are obtained at thirty evolutions of the generation. 相似文献
65.
George Christakos 《Mathematical Geology》1988,20(2):111-133
Recursive algorithms for estimating states of nonlinear physical systems are presented. Orthogonality properties are rediscovered and the associated polynomials are used to linearize state and observation models of the underlying random processes. This requires some key hypotheses regarding the structure of these processes, which may then take account of a wide range of applications. The latter include streamflow forecasting, flood estimation, environmental protection, earthquake engineering, and mine planning. The proposed estimation algorithm may be compared favorably to Taylor series-type filters, nonlinear filters which approximate the probability density by Edgeworth or Gram-Charlier series, as well as to conventional statistical linearization-type estimators. Moreover, the method has several advantages over nonrecursive estimators like disjunctive kriging. To link theory with practice, some numerical results for a simulated system are presented, in which responses from the proposed and extended Kalman algorithms are compared. 相似文献
66.
中国饮食文化的区域分化和发展趋势 总被引:30,自引:2,他引:30
现代地理学主要研究地球表层的“地体”与“地象”的区域特征和地域分异的时空发展规律。以食品和菜肴为“地体”,与餐饮有关的文化作为“地象”出发,本文通过饮食文化的地域分异、菜系的形成,中国四大菜系的比较研究,阐述中国饮食文化的区域特征和地域分化的时空发展规律,并预测其发展趋势。 相似文献
67.
Zhang Shuangxi 《中国地质大学学报(英文版)》1994,(1)
FrequencyEffectsofFineThinLayer¥ZhangShuangxi(EepartmentofGeophysics,ChinaUniversityofGeosciences,Wuhan430074)YuanTao;ZhangWe... 相似文献
68.
随机地震模型及反应谱分析 总被引:2,自引:0,他引:2
本文以实际地震加速度的频谱特性和相位谱特性为依据,仿概率统计理论中的高斯概率密度函数,建立了随机地震加速度频数学模型。 相似文献
69.
基于粗规则对象空间信息表的最小规则集生成 总被引:4,自引:1,他引:4
提出了粗规则对象空间信息表的概念、相关概念和性质,并给出实现粗规则最小化算法。基于此,编写了相应的计算机程序,并对一个地理信息系统实例规则进行了研究。实例表明运行可靠、结果正确,可应用于智能决策信息系统的知识库优化。 相似文献
70.