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101.
Chia-Cheng Tsai 《计算机、材料和连续体(英文)》2011,22(3):197-218
This paper describes the combination of the method of fundamental solutions (MFS) and the dual reciprocity method (DRM) as a meshless numerical method to solve problems of Kirchhoff plates under arbitrary loadings. In the solution procedure, a arbitrary distributed loading is first approximated by either the multiquadrics (MQ) or the augmented polyharmonic splines (APS), which are constructed by splines and monomials. The particular solutions of multiquadrics, splines and monomials are all derived analytically and explicitly. Then, the complementary solutions are solved formally by the MFS. Furthermore, the boundary conditions of lateral displacement, slope, normal moment, and effective shear force are all given explicitly for the particular solutions of multiquadrics, splines and polynomials as well as the kernels of MFS. Finally, numerical experiments are carried out to validate these analytical formulas. In these numerical experiments, homogeneous problems are first considered to find the best location of the MFS sources by the way proposed by Tsai, Lin, Young and Atluri (2006). Then the corresponding nonhomogeneous problems are solved by the DRM based on both the MQ and APS. The numerical results demonstrate that the MQ is in general more accurate than the thin plate spline, or the first order APS, but less accurate than the high order APSs. Overall, this paper derives a meshless numerical method for solving problems of Kirchhoff plates under arbitrary loadings with all kinds of boundary conditions by both the MQ and APS. 相似文献
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103.
为探究个体与系统状态的演化,构建了个体行为策略与网络结构的演化模型,探讨个体在利他激励机制下对合作演化的影响。在该模型中,个体首先通过对其他个体的帮助获得一定的额外互惠收益,并通过个体混合收益累计个体收益与帮助其他个体获得额外收益的加权,以此来激励个体合作。然后在博弈过程中,通过个体混合收益取代费米函数中的个体累计收益用于促进个体选择利他合作策略,从而促进整个群体的总收益与合作水平。蒙特卡罗仿真实验结果表明,个体在利他激励机制下更愿意帮助其他个体。在不同网络结构中,小世界网络最能扩散利他激励机制,其系统合作者密度最高。 相似文献
104.
针对传统有源电磁式互感器易饱和、稳定性与抗干扰能力差、安装受限等问题,本文基于Faraday磁光效应,设计了一种无源全光纤电流互感器,通过旋光角来测量被测电流;设计互感器以HB Spun光纤作为传感元件,无饱和现象,可用于大电流测量;利用光学互易回路,消除光路中温度、光纤缺陷等因素对旋光角测量的干扰;采用反射式光路将电场引起的旋光角放大4倍,实现小电流的精确测量;传感元件采用柔性传感光纤环结构,形状可变,适应复杂空间内电流的测量。对比了不同圈数的柔性光纤传感环与标准电流互感器的测量精度,结果表明,本文设计的光学互易回路可以消除温度对电流测量的影响,全光纤电流互感器在-5℃~70℃全温度范围内精度为0.5,可实现小电流的精确测量。 相似文献
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107.
The pursuit of highest payoffs in evolutionary social dilemmas is risky and sometimes inferior to conformity. Choosing the most common strategy within the interaction range is safer because it ensures that the payoff of an individual will not be much lower than average. Herding instincts and crowd behaviour in humans and social animals also compel to conformity in their own right. Motivated by these facts, we here study the impact of conformity on the evolution of cooperation in social dilemmas. We show that an appropriate fraction of conformists within the population introduces an effective surface tension around cooperative clusters and ensures smooth interfaces between different strategy domains. Payoff-driven players brake the symmetry in favour of cooperation and enable an expansion of clusters past the boundaries imposed by traditional network reciprocity. This mechanism works even under the most testing conditions, and it is robust against variations of the interaction network as long as degree-normalized payoffs are applied. Conformity may thus be beneficial for the resolution of social dilemmas. 相似文献
108.
Songping Zhu 《Engineering Analysis with Boundary Elements》1993,12(4):261-274
A numerical model using the dual reciprocity boundary element method (DRBEM) is developed to study the combined refraction and diffraction of water waves propagating around islands or solid offshore structures over a seabed with a variable depth. Based on the well-known mild-slope equation, the model has been validated by comparison with both analytical solutions and standard numerical solutions available in the literature. The results show that a considerable improvement in terms of numerical efficiency has been achieved with the adoption of the DRBEM and the model has a great potential to be used in engineering practice to solve wave refraction and diffraction problems. 相似文献
109.
Andrzej J. Nowak 《Engineering Analysis with Boundary Elements》1995,16(4):323-332
In this paper types of nonlinear potential problems are discussed and some of these problems are solved by the boundary element method. In order to avoid domain discretization the multiple reciprocity method is used. Solution of the problem is expressed in terms of a series which involves the higher order fundamental solutions and Laplacians of source terms. Convergence criteria as well as numerical examples are included. 相似文献
110.
This paper presents a new method for determining the natural frequencies and mode shapes for the free vibration of thin elastic plates using the boundary element and dual reciprocity methods. The solution to the plate's equation of motion is assumed to be of separable form. The problem is further simplified by using the fundamental solution of an infinite plate in the reciprocity theorem. Except for the inertia term, all domain integrals are transformed into boundary integrals using the reciprocity theorem. However, the inertia domain integral is evaluated in terms of the boundary nodes by using the dual reciprocity method. In this method, a set of interior points is selected and the deflection at these points is assumed to be a series of approximating functions. The reciprocity theorem is applied to reduce the domain integrals to a boundary integral. To evaluate the boundary integrals, the displacements and rotations are assumed to vary linearly along the boundary. The boundary integrals are discretized and evaluated numerically. The resulting matrix equations are significantly smaller than the finite element formulation for an equivalent problem. Mode shapes for the free vibration of circular and rectangular plates are obtained and compared with analytical and finite element results. 相似文献