Papers by Keyword: Computational

Abstract: The paper reported a study on an effect of the point charge of the bio-interface of a nanowire field biosensor on the conductance of the nanowire, through finite element calculations using COMSOL Multiphysics. A model with 5 layers starting with silicon nanowire of radius 10nm surrounded by a 2-nm oxide layer, and the oxide layer were surrounded by a 5 nm thick functional layer and 2 points charge were considered for this study and last layer is for electrolyte. The results shows that is different voltages with points change is that effected on the conductance of nanowire that is clear from different of potential distribution of point charge.

Abstract: Traffic is a major source of environmental noise in modern society. Subsequently, the development of new vehicles is subjected to heavy governmental legislations. The major noise source on common road vehicles during acceleration is the flow noise caused by turbulent exhaust gas. The main goal of this work is to develop an appropriate Aeroacoustic simulation method to investigate the acoustic of sound on exhaust automotive muffler. The range of validity of the method is studied comparing results to experimental data. The Computational Aeroacoustics (CAA) results are compared with an experimental test in a vehicle during its acceleration and the mean flow model of the muffler has a satisfactory mesh with a suitable inlet boundary provided by an engine dynamometer data. The present work describes a good agreement between computational and experimental approach for the Aeroacoustics behavior of a specific configuration of exhaust muffler.

Abstract: A stochastic optimization procedure incorporating a continuum modelling is used to identify the optimal texture (orientation distribution) parameters of ferroelectrics (FEs) for piezoelectric applications. FE polycrystals differ significantly from single crystals because of the presence of variously oriented crystallites. The orientation of FE crystals plays a critical role in the anisotropy of their piezoelectric properties. The set of combination of variables, known as solution space, which dictates the texture of crystallites is unlimited. Crystallographic orientation in FEs is characterised through Euler angles . The macroscopic properties of a ceramic FE, differ significantly from those of single crystals mainly due to the imperfect alignment of the crystallographic axes of the constituent domains or crystallites. This suggests that piezoelectric properties can be tailored by a proper choice of the parameters which control the orientation distribution. Nevertheless, this choice is complicated and it is impossible to analyze all possible combinations of the distribution parameters or the angles themselves. Stochastic optimization combined with a generalized Monte Carlo scheme optimizes the objective functions, the effective piezoelectric coefficients . Objective functions are calculated using the homogenization method at each orientation configuration chosen by the optimization algorithm. A modified simulated annealing is employed to describe the stochastic optimization. Here we have simulated the texture of polycrystals using a simple model with a Gaussian distribution. Optimal design variables that enhance the macroscopic piezoelectricity are identified.

Abstract: The importance of modelling as a tool in the design of both refractory structures and materials is considered. Both bulk refractory structures as well as refractory microstructure are considered. Whilst computational models are emphasised, contrasts and synergy between physical and computational modelling are drawn. It is shown that the range of structures, materials and environments that can be considered as part of a design process is vastly increased by the use of models.