Cheng-Hung San¹, Chuang-Pin Chiu¹, Che-Wun Hong^1,2

CMC-Computers, Materials & Continua, Vol.26, No.3, pp. 167-186, 2011, DOI:10.3970/cmc.2011.026.167

Abstract An improvement in the catalytic process of oxygen reduction reactions is of prime importance for further progress in low temperature fuel cell performance. This paper intends to investigate this problem from a fundamental quantum mechanics viewpoint. For this purpose, a hybrid density functional theory is employed to analyze the catalytic mechanism of the oxygen reduction at the fuel cell cathode. Major steps in the oxygen reduction that include the oxygen adsorption on solid metal clusters (e.g. Cu and Pt) and complete four proton transfer steps are simulated. Proton transfer processes from hydroniums to the adsorbed oxygen molecules to produce water… More >

Sunil Kr. Jha¹, Zulfiqar Ahmad²

CMES-Computer Modeling in Engineering & Sciences, Vol.113, No.4, pp. 443-459, 2017, DOI:10.3970/cmes.2017.113.443

Abstract Microbial population and enzyme activities are the significant indicators of soil strength. Soil microbial dynamics characterize microbial population and enzyme activities. The present study explores the development of efficient predictive modeling systems for the estimation of specific soil microbial dynamics, like rock phosphate solubilization, bacterial population, and ACC-deaminase activity. More specifically, optimized subtractive clustering (SC) and Wang and Mendel's (WM) fuzzy inference systems (FIS) have been implemented with the objective to achieve the best estimation accuracy of microbial dynamics. Experimental measurements were performed using controlled pot experiment using minimal salt media with rock phosphate as sole carbon source inoculated with… More >

R.D. Phillips¹, M.S. Hossain¹, L.T. Watson^1,2, R.H. Wynne³, Naren Ramakrishnan¹

CMES-Computer Modeling in Engineering & Sciences, Vol.97, No.2, pp. 175-197, 2014, DOI:10.3970/cmes.2014.097.175

Abstract Clusters, typically mined by modeling locality of attribute spaces, are often evaluated for their ability to demonstrate ‘enrichment’ of categorical features. A cluster enrichment procedure evaluates the membership of a cluster for significant representation in predefined categories of interest. While classical enrichment procedures assume a hard clustering definition, this paper introduces a new statistical test that computes enrichments for soft clusters. Application of the new test to several scientific datasets is given. More >

J.E. Lee¹and S.J. Kim²

CMES-Computer Modeling in Engineering & Sciences, Vol.86, No.2, pp. 93-112, 2012, DOI:10.3970/cmes.2012.086.093

Abstract As the option trading nowadays has become popular, it is important to simulate efficiently large amounts of option pricings. The purpose of this paper is to show valuations of large amount of options, using network distribute computing resources. We valuated 108 options simultaneously on the self-made cluster computer system which is very inexpensive, compared to the supercomputer or the GPU adopting system. For the numerical valuations of options, we developed the option pricing software to solve the Black-Scholes partial differential equation by the finite element method. This yielded accurate values of options and the Greeks with reasonable computational times. This… More >

Zone-Ching Lin¹, Chen-Hsing Cheng²

CMES-Computer Modeling in Engineering & Sciences, Vol.68, No.1, pp. 25-54, 2010, DOI:10.3970/cmes.2010.068.025

Abstract This study considers loadings on the multi-layer web frame structure and uses a novel method of the modified analytical hierarchy process (AHP) combined with modified theory of inventive problem solving (TRIZ) clustering to perform the creative structure design. The engineering knowledge of multi-layer web frame structure comprises such issues as vibration, yielding and buckling strength. Using the modified AHP, this study firstly applies the ratios of occurrence numbers of related keywords on different hierarchies to analyze the techniques and functions of multi-layer web frame structure, and finds out the priority order of feasible design decisions. Furthermore, this study also proposes… More >

Jong Keun Moon¹, Seung Jo Kim²

CMES-Computer Modeling in Engineering & Sciences, Vol.67, No.3, pp. 239-264, 2010, DOI:10.3970/cmes.2010.067.239

Abstract Large structural problems with high precision and complexity require a high-performance computation using the efficient parallel algorithm. The purpose of this paper is to present the parallel performance of thermal-structural coupled analysis tested on a parallel cluster system. In the coupled analysis, the heat transfer analysis is carried out, and then the structural analysis is performed based on temperature distribution. For the automatic and efficient connection of two parallel analysis modules, the several communication patterns were studied. The parallel performance was demonstrated for the sample and the real application problems, such as a laminated composite material by the DNS(Direct Numerical… More >

Che-Wun Hong^1,2, Chia-Yun Tsai¹

CMES-Computer Modeling in Engineering & Sciences, Vol.67, No.2, pp. 79-94, 2010, DOI:10.3970/cmes.2010.067.079

Abstract This paper describes the quantum mechanical simulation on the photonic properties of group-III nitride clusters, whose bulk types are common materials for light emitting diodes (LEDs). In order to emit different colors of light using the same semiconductor materials, it is possible to vary the band gap by controlling the quantum dot sizes or doping a third atom theoretically. Density functional theory (DFT) calculations are performed to analyze a set of binary (GaN)_n (3≤n≤32) and ternary In_xGa_1-xN (0≤x≤0.375) clusters to study their photonic characteristics. The ground state structures are optimized to calculate the binding energies using the time-independent DFT. Then… More >

C. J. F. Solano, A. Costales, E. Francisco, A. Martín Pendás, Miguel A. Blanco¹, K.-C. Lau, H. He, Ravindra Pandey²

CMES-Computer Modeling in Engineering & Sciences, Vol.24, No.2&3, pp. 143-156, 2008, DOI:10.3970/cmes.2008.024.143

Abstract The buckling of hexagonal layers in bulk and nanostructures of AlN is analyzed in the framework of atomistic and first principles techniques. At ambient conditions, the wurtzite structure (B4) of AlN consists of buckled hexagons. On the other hand, a non-buckled B_k structure is found to be metastable at zero pressure, being favored at higher pressures. It is suggested that the energy ordering of B4 and B_k may change in finite systems; an assertion tested in this study by considering finite slabs, nanobelts, and nanorings, and comparing the results with the previous studies on small clusters, and periodic nanostructures. We… More >

A. Aimi¹, M. Diligenti¹, F. Lunardini¹, A. Salvadori²

CMES-Computer Modeling in Engineering & Sciences, Vol.4, No.1, pp. 31-50, 2003, DOI:10.3970/cmes.2003.004.031

Abstract This paper is devoted to the study of a new application of the Panel Clustering Method [Hackbusch and Sauter (1993); Hackbusch and Nowak (1989)]. By considering a classical 3D Neumann screen problem in its boundary integral formulation discretized with the Galerkin BEM, which requires the evaluation of double integrals with hypersingular kernel, we recall and use some recent results of analytical evaluation of the inner hypersingular integrals. Then we apply the Panel Clustering Method (PCM) for the evaluation of the outer integral. For this approach error estimate is shown. Numerical examples and comparisons with classical PCM technique are presented. More >

E. Kuramoto, K. Ohsawa, T. Tsutsumi¹

CMES-Computer Modeling in Engineering & Sciences, Vol.3, No.2, pp. 193-200, 2002, DOI:10.3970/cmes.2002.003.193

Abstract In order to investigate the interaction of point defects with a dislocation, an interstitial cluster or a SFT (stacking fault tetrahedron), computer simulation has been carried out in model Fe and Ni crystals. The capture zone (the region where the interaction energy is larger than kT) was determined for various interactions. Calculated capture zone for T =500°C for SIAs (crowdion and dumbbell) around a straight edge dislocation is larger than that for a vacancy in both Fe and Ni. Capture zones for Ni are larger than those for Fe, suggesting that Ni (fcc) has a larger dislocation bias factor than… More >