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Abstract: This paper presents a new optimization technique called water cycle algorithm (WCA) which is applied to a number of constrained optimization and engineering design problems. The fundamental concepts and ideas which underlie the proposed method is inspired from nature and based on the observation of water cycle process and how rivers and streams flow to the sea in the real world. A comparative study has been carried out to show the effectiveness of the WCA over other well-known optimizers in terms of computational effort (measures as number of function evaluations) and function value (accuracy) in this paper. [Copyright &y& Elsevier]

In the present paper two base isolation systems are analyzed and their seismic behavior is compared with reference to a multi-storey reinforced concrete building. The base isolation systems have been designed in compliance to the European seismic codes EC2 and EC8. A base isolated building is adopted which is characterized by strong irregularity in plan. A comparative analysis is presented for evaluating the behavior of the structure subject to seismic events. Two base isolation systems have been considered in the analysis, the High Damping Rubber Bearing (HDRB) actuated in parallel with a Friction Slider (FS) and the Lead Rubber Bearing (LRB) also actuated in parallel with a Friction Slider (FS). A dynamic nonlinear analysis is performed for the three-dimensional base isolated structure. Recorded accelerograms for bi-directional ground motions compatible with the reference elastic response spectrum have been used for the evaluation of the seismic response of the structure. The seismic assessment and the dynamic nonlinear analysis of the base isolated structure are illustrated by presenting a comparative analysis of the behavior of the structure isolated by the two considered base isolation systems and the corresponding behavior of the traditional fixed base structure. [ABSTRACT FROM AUTHOR]

This paper presents an alternative reanalysis algorithm based on the block matrix to address problems with local modifications. In this method, the modified stiffness can be classified as three parts: influenced region, stationary region and an interface region between them. The main computation cost concentrates on the influenced region by this specific blocked strategy. Compared with popular reanalysis methods, the proposed method can achieve an accurate response for large modification with lower computation cost. Several practical engineering problems are analyzed and the results are exactly as that performed by full analysis. [ABSTRACT FROM AUTHOR]

Abstract: A widely used strategy to explore the sensitivity of the model to its inputs is based on a finite set of simulations. These are usually performed for a chosen set of points in a parameter space. An estimate of the sensitivity can be then obtained by computing correlations between the model inputs and outputs. The accuracy of the sensitivity prediction depends on a quality of the points distribution in the parameter space, so-called the design of experiments. The aim of the presented paper is to review and compare available criteria determining an optimal design of experiments for sampling-based sensitivity analysis. [Copyright &y& Elsevier]

Abstract: In this paper, the recently developed method, so-called ray optimization, is employed for size and shape optimization of truss structures. The goal function of the present optimization method is the minimization of truss weight under the required constraints. In ray optimization, each agent is modeled as a ray of light that moves in the search space in order to find the global or near-global optimum solution. Comparison of the obtained results with those of some previous studies demonstrates the efficiency of this new algorithm. [Copyright &y& Elsevier]

Abstract: This paper presents an adaptive density point refinement approach for continuum topology optimization on the basis of an analysis-mesh separated material density field description based on nodal design variables. The Shepard interpolants are used to construct a strictly range-restricted density field over the design domain with the density design variables defined on a density point grid. Since the density points are defined independent of the finite element mesh, it is easy to refine the density point grid without remeshing the finite element model. A refinement criterion is given to identify the gray transitional regions to be adaptively refined in the subsequent optimization iterations. With such a refinement scheme, the topology optimization can start from a relatively coarse density point grid but still yields a desired higher resolution of the structural boundaries in the final design. Because refinements are only performed when and where necessary, this method is able to improve the boundary description quality of the optimal result with much less design variables as compared with the case of global refinement, and therefore can greatly reduce the computational burden involved in the sensitivity analysis and optimization process. Moreover, the percentage of transitional regions in the final solutions can also be reduced. Compared with using a uniformly globally-dense density point arrangement, this approach can achieve similar optimal designs but with much less computational cost. Numerical examples are given to demonstrate the effectiveness and efficiency of the present approach. [Copyright &y& Elsevier]

Abstract: This paper describes features of a fully coupled thermo-mechanical model for Friction Stir Welding (FSW) simulation. An apropos kinematic setting for different zones of the computational domain is introduced and an efficient coupling strategy is proposed. Heat generation via viscous dissipation as well as frictional heating is considered. The results of the simulation using the proposed model are compared with the experimental evidence. The effect of slip and stick condition on non-circular pin shapes is analyzed. Simulation of material stirring is also carried out via particle tracing, providing insight of the material flow pattern in the vicinity of the pin. [Copyright &y& Elsevier]

Abstract: This paper gives a concise overview of three approaches to nonlinear regression modelling with feed-forward neural networks, involving the use of evidence framework and full Bayesian inference with Markov chain Monte Carlo stochastic sampling. The article then presents an empirical assessment of these approaches using a benchmark regression problem for compressive strength prediction of high-performance concrete. Results on applying various methods to benchmark dataset show that Bayesian approach with the MCMC sampling approximation of learning and prediction gives the best prediction accuracy. [Copyright &y& Elsevier]

Abstract: In this paper, known analytical solutions are used to compare various finite element discretizations for the numerical solution of large deformation problems involving hyperelastic materials. This approach is also known as the method of manufactured solutions (MMS). The performance of these different discretizations is analyzed in terms of convergence in a suitable norm with respect to mesh size, and also in terms of computational cost and memory consumption. Some interesting features of mixed finite element discretizations are presented and discussed. The test cases presented can also serve as nontrivial benchmark problems and as a basis for code verification. [Copyright &y& Elsevier]

Abstract: Mid-frequency response analysis often faces computational difficulties when a conventional modal approach is used for a finite element linear system. In this paper, the computational burden is relieved by frequency sweep algorithm or mode acceleration method for a reduced-order system constructed by algebraic substructuring, a variant of model order reduction. The two methods are compared with the help of numerical experiments and their computational complexity. As demonstrated by the finite element simulations, in which proportional damping is assumed, of a turbo-prop aircraft and a ring resonator, the frequency sweep algorithm for reduced-order systems shows the best performance among all considered numerical solutions, including the conventional approach. [Copyright &y& Elsevier]

The floating frame of reference approach is used for the analysis of the in-plane oscillations of the suspended rectangular plate. The deformation is interpolated by means of polynomial shape functions. The equations of motion become nonlinear in the deformation degrees of freedom both due to the geometrically nonlinear deformation model and to the inertial coupling between the rotation and the deformation of the body. Consistent linearization with respect to the deformation degrees of freedom simplifies the equations significantly and speeds up the time integration. A convergence study with respect to the maximum interpolation order is performed. The comparative analysis of different problem statements and their ranges of applicability is presented in the paper. [Copyright &y& Elsevier]