International Journal of Modeling, Simulation, and Scientific Computing

In this paper, we propose a new high accuracy discretization based on the ideas given by Chawla and Shivakumar for the solution of two-space dimensional nonlinear hyperbolic partial differential equation of the form u_tt = A(x, y, t)u_xx + B(x, y, t)u_yy + g(x, y, t, u, u_x, u_y, u_t), 0 < x, y < 1, t > 0 subject to appropriate initial and Dirichlet boundary conditions. We use only five evaluations of the function g and do not require any fictitious points to discretize the differential equation. The proposed method is directly applicable to wave equation in polar coordinates and when applied to a linear telegraphic hyperbolic equation is shown to be unconditionally stable. Numerical results are provided to illustrate the usefulness of the proposed method.

The research proposes a simulation model combined with smart optimizer based on Artificial Intelligence techniques, in order to support service and maintenance of pools within Complex Systems, such as power plants or vessel/aircraft fleet.

The authors propose an innovative methodology allowing the evaluation and the optimization of service and maintenance policies in order to improve inventory management and scheduling operations within complex systems. This methodology is based on the development of a simulator combined with an intelligent optimizer.

The authors proposed a new metrics to evaluate the real performance of pool service management of the whole complex system and support the optimization processes.

It is important for the wireless communication field to conduct research on large-scale complex electromagnetic environment (CEME) simulation. There exist many models for computing CEME simulation, including empirical models, half-empirical or half-deterministic models and deterministic models. Most of these models cannot obtain satisfactory results due to the limitation of the capacity of computers. The ray tracing (RT) and parabolic equation (PE) methods are very suitable for large-scale CEME simulation. Based on the introduction of RT and PE, qualitative comparisons of the two methods are analyzed in view of algorithm theory, the category of the model, solution to the model and the application field, and then four specific indices are focused on to analyze the computational complexity, accuracy, speed and parallelism in details. The numerical experiments are presented by the three-dimensional (3D) RT method employing the software of Wireless InSite (WI) and a quasi-3DPE method using the sliced method. Although both RT and PE methods can achieve high speedup using coarse-grained parallel computing, the experimental results indicate that the PE method can obtain a higher speed than the RT method, and the two methods can acquire an approximate precision. A hybrid procedure using both RT and PE methods can obtain a better result for solving CEME problems.

This paper deals with the study of experimental current intensity/voltage characteristics of a free burning arc that appears to be singular: At low intensity current, the arc voltage decreases until a minimum value, corresponding to a critical current intensity I_c. For current intensities higher than I_c, there is an increase of the arc voltage with the current intensity. Dimensional analysis and Pi theorem coupled with a large set of experimental data allow us to evaluate the main physical processes responsible for the characteristics shape. At low current intensity, the plasma is mostly driven by thermal conduction effects while at high current intensity, it is principally governed by radiation losses. Finally, the results obtained from dimensional analysis allow to propose a 1D numerical simulation of the plasma column that gives rather good qualitative results.

A numerical model based on the dual-reciprocity boundary element method (DRBEM) for studying the transient magneto-thermo-viscoelastic waves in a rotating nonhomogeneous anisotropic solid is presented. The formulation is tested through its application to the problem of an initially stressed solid placed in a constant primary magnetic field acting in the direction of the z-axis and rotating about this axis with a constant angular velocity. In the case of plane deformation, a numerical scheme for the implementation of the method is presented and the numerical computations are carried out for the temperature, displacement components and thermal stress components. The validity of DRBEM is examined by considering a magneto-thermo-viscoelastic solid occupies a rectangular region and good agreement is obtained with existent results. The results obtained are presented graphically to show the influence of initial stress on the displacement components and thermal stress components.

In this paper, a nonlinear mathematical model is proposed and analyzed to study the effects of population pressure augmented industrialization on the survival of competing species dependent on resource. It is assumed that the growths of competing species are logistic and carrying capacities increase with increase in the density of resource biomass. Further, it is assumed that the resource biomass too is growing logistically in the environment and its carrying capacity decreases with the increase in densities of competing species and industrialization. The growth rate of population pressure is assumed to be proportional to the densities of competing species. Stabilities of all equilibria and conditions which influence the permanence of the system are carried out using theory of differential equations. Numerical simulations are performed to accomplish our analytical findings. It is shown that the equilibrium density of resource biomass decreases as (i) the growth rate coefficient of population pressure increases (ii) the growth rate coefficient of industrialization due to population pressure increases and (iii) the growth rate coefficient of industrialization due to resource biomass increases. It is found that the competitive outcome alters with increase in the growth rate coefficient of population pressure. Decrease in the equilibrium densities of competing species is also noted with increase in the growth rate coefficient of industrialization due to resource biomass.

The benefits of the use of modeling and simulation in engineering are acknowledged widely. It has proven its advantages e.g., in virtual prototyping i.e., simulation aided design and testing as well as in training and R&D. It is recognized to be a tool for modern decision making. However, there are still reasons that slow down the wider utilization of modeling and simulation in companies. Modeling and simulation tools are separate and are not an integrated part of the other engineering information management in the company networks. They do not integrate well enough into the used CAD, PLM/PDM and control systems. The co-use of the simulation tools themselves is poor and the whole modeling process is considered often to be too laborious. In this article we introduce an integration solution for modeling and simulation based on the semantic data modeling approach. Semantic data modeling and ontology mapping techniques have been used in database system integration, but the novelty of this work is in utilizing these techniques in the domain of modeling and simulation. The benefits and drawbacks of the chosen approach are discussed. Furthermore, we describe real industrial project cases where this new approach has been applied.

This study reports the results of a finite element simulation of powder mixed electric discharge machining process for H11 Hot Die steel material using relevant boundary conditions and reasonable assumptions. The crater shape was developed using simulated temperature profiles to estimate the volume removed in a single crater. The temperature distribution on the workpiece was used to predict the cooling rate and calculate the stresses generated due to thermal loading. Subsequently, the simulation results were experimentally validated by physically measuring the crater shape and volume. From the results it was concluded that about 25% of heat is transmitted to the workpiece during machining at the process conditions used in the experiment. The microscopic pictures showed bigger craters with increase in current. The machined surface showed overlapping craters with surface cracks suggesting a high cooling rate.