Journal of Computational Science & Engineering

Abstract:In this paper, a new nonlinear modified DY conjugate gradient method with wolfe type line search for solving unstrained optimization problems is proposed. The direction generated by the method is a descent direction. Under some conditions, we prove that the modified DY conjugate gradient method with Wolfe type line search is global convergence. Finally, the numerical results show that the new method is efficient for unconstrained optimizations.

Abstract:Quantitative structure-property relationship (QSPR) models, which could predict odor threshold of aliphatic alcohols, were developed by applying chemical descriptors computed with quantum chemical PM3 algorithm and using linear and nonlinear method, respectively. Both of the models gave acceptable results. The model of nonlinear radial basis function neural networks (RBFNN) leads to a squared correlation coefficient (R2) of 0.76 and root-mean-square error (RMS) of 0.528 for the test set and the values for linear model are 0.62 and 0.689 respectively. The QSPR models provide a rapid, simple and valid way to predict the odor threshold of aliphatic alcohol.

Abstract: The mechanism of the thermolysis reaction of monohydrate magnesium chloride was studied detailedly by PM3 method. The geometrical parameters, harmonic vibrational frequencies and energies of stationary points on the potential energy surface were obtained. Two reaction paths have been proposed for the subject reaction with the major reactive channel corresponding to the dissociation of the monohydrate magnesium chloride. The calculated results show that the best strategy for controlling the hydrolysis reaction is decreasing the reactivity of magnesium chloride so that preventing the dehydrogen reaction process. Simultaneity, the addition of the Nano-metal catalysis also restrains the hydrolysis reaction.

Abstract: The discretization of continuous attributes is an important issue in the research of rough sets theory. It makes a great contribution to the process of knowledge acquirement. There are two steps selecting candidate cuts and confirming result cuts during the process of searching the cuts which are used to discretize continuous data. This paper puts forward a novel algorithm for selecting the sets of candidate cuts in the first step. In the second step, a top-down approach is adopted to confirm the importance of candidate cuts and a heuristic algorithm is proposed to figure out the cuts which are ultimately used in the discretization process. The simulation results demonstrate the validity of the new algorithm.

Keywords: sets, continuous, attributes, cuts, discretization.

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Abstract:Density functional theory calculations (DFT) have been carried out on the four kinds of Gallium complexes [Ga(edt)Cl2]-(1),[Ga(edt)2]-(2)anions and [Ga(edt)2M(PPh3)2] (M = Cu 3, Ag 4), (edt=-SC2H4S-). The properties, including the structure, charge, the energy and composition of the frontier molecular orbitals and absorbance spectrum, have been obtained and compared. The calculated results show that the distance of Ga-Cu in 3 is shorter than the one of Ga-Ag in 4 and the interaction of Ga-Cu is stronger than the one of Ga-Ag. The order of the energy gap between HOMO and LUMO in complexes is 1 > 2 > 3> 4 and the wave length of the first absorbance can be estimated. In the composition of frontier molecular orbital, the HOMOs are mainly composed of S and the LUMOs are dominantly composed of S for 1 and 2, PPh3 and M for 3 and 4, respectively. Moreover, a further illumination for the nature of electronic transitions are made on the absorbance spectrum. Both in 3 and 4, the electrons are easy to be excited to the higher orbitals and there excited states exist. The complexes are of good photovoltaic properties, which indicate that they are promising precursors to the solar cells...

Abstract: The trust worthy B3LYP/6-311+G* method is employed to investigate the double hydrogen-bonded system with a special emphasis on oxidation and hydration effect. Proton transfer occurs spontaneously upon oxidation from amido group to adjacent imidazole fragment. The larger the pH value of the environment is, the significant the influence to the geometry structure is. The electron population on the HOMO orbital determines the IR vibrational frequency of the H-bond being blue-shift or red-shift. The complex prefers to be oxidized under the basic condition. The weak acidic environment is recommended to prevent the DNA mutation.