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Abstract: This paper shows how advanced numerical methods can help to improve the thermal efficiency of walls made up of multi-holed bricks with large recesses. In order to get this objective, a new methodology based on different numerical simulations is presented here. With the help of the finite element analysis (FEA), we present an optimization procedure in order to determine the best candidate brick with large recesses from the thermal point of view. With respect to the ecological design and the energy saving for housing and industrial structures, there is also a great interest in light building materials with good physical and thermal behaviours, which fulfils all thermal requirements of the new CTE Spanish rule for further energy savings. On one hand, we want to validate the numerical analysis procedure, based on the simulation of three-dimensional walls by the finite element method (FEM). On the other hand, we have analyzed the material conductivity for different compositions of the light concrete. The FEM technique is used for finding accurate solutions of the heat transfer equation in walls made up of light concrete multi-holed bricks with large recesses. Mathematically, the non-linearity is due to the radiation boundary condition inside the inner recesses of the bricks. Next, the thermal optimization of the walls is carried out from the FEM technique of several hollow brick geometries using the average mass overall thermal efficiency and the equivalent thermal conductivity. In order to select the appropriate wall satisfying the CTE requirements, detailed instructions are obtained and indicated to the readers. Finally, conclusions of this paper are exposed. [Copyright &y& Elsevier]

Abstract: A temporal finite element discretization of a boundary value problem has several advantages compared to a time-integrating evolution form for optimized target movement simulations. The paper gives some basic aspects on how such a finite element form can be stated, with both displacements and controls discretized and seen as unknowns. Aspects on the resulting formulations are discussed. Important issues are the order, continuity and fineness of the discretizations. When the formulation is seen in an optimization context, minimizing the effort for a prescribed movement, the discretization affects the results obtained in several manners, where some aspects of results are artifacts. The paper discusses these effects from basic principles, but also verifies them in numerical simulations. [Copyright &y& Elsevier]

Abstract: In this paper, single and bi-layered tube hydroforming processes were numerically simulated using the finite element method. It was found that the final bulges heights resulted from the models were in good agreement with the experimental results. Both types of modeling have been kept with the same geometry, tube material, and process parameters to compare between the obtained hydroformed products (branch height, thickness reduction, and wrinkling) using different loading path types. Results were discussed. [Copyright &y& Elsevier]

Abstract: The application of numerical simulation techniques for the analysis and optimization of the acoustic behavior of all kinds of products has become very important in almost every phase of a design process. The large computational burden associated with the Finite Element Method (FEM) limits its applicability to low-frequency problems. Recently, the Wave Based Method (WBM) was proposed as an efficient alternative to the element based methods. This method is based on an indirect Trefftz approach, using an expansion of exact solutions of the governing differential equation to describe the dynamic field variables. An important disadvantage of the WBM is the limited geometrical flexibility as compared to the element based techniques. This paper aims to alleviate the geometrical restrictions by using B-splines for the efficient description of curved edges. The introduction of B-splines within the WBM requires an adaptation of the numerical integration procedure used to evaluate the weighted residual formulation. To this end, different types of numerical integration techniques are studied: the Gauss–Legendre and the Romberg integration procedure. A comparative study with the finite element method and the original WBM indicates that the application of B-splines and the adapted numerical integration procedure leads to accurate and computationally affordable WB models. [ABSTRACT FROM AUTHOR]

To analyze dielectric waveguides, an iterative procedure coupling the finite-element method in the interior to an integral equation of the exterior domain is developed. The robustness of this method is confirmed by the numerical results presented in this paper and corresponding the computation of the propagation constant. [ABSTRACT FROM AUTHOR]

An adaptive mesh refinement scheme in the finite element method is presented in this paper. The new criterion Bdiff for adaptive refinement is tested for its validity. A technique for approximating curved boundaries employing the concept of triangle subdivision in conjunction with Delauney triangulation is also considered, so that the mesh produced is optimal. The implementation of the adaptive mesh refinement criterion in conjunction with the proposed technique of including the curved boundaries in the finite element model is described in detail and several examples of its application are given by way of illustration. [ABSTRACT FROM AUTHOR]