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A new formulation for fast calculation of far field force in molecular dynamics simulations

Authors: Nguyen, Hai ChauKeywords: formulation;fast calculation;far field force;molecular dynamics simulationsIssue Date: 2007Publisher: H. : ĐHQGHNSeries/Report no.: Vol. 23;No. 1 (2007)Abstract: We have developed a new formulation for fast calculation of far-field force of fast multipole method (FMM)in molecular dynamics simulations. FMM is a linear algorithm to calculate force for molecular dynamics simulations. GRAPE is aspecial-purpose computer at the same price. However FMM cannot be implemented directtly on GRAPE. We have succeeded to implement FMM on GRAPE adn developed a new formulation for far-field force calculation. Numerical tests show that the performance of FMM using our new formulation on GRAPE is approximately 2-5 times faster than that of FMM using conventional far field formulation.Description: p. 122-130URI: http://repository.vnu.edu.vn/handle/VNU_123/57473ISSN: 2588-1124Appears in Collections:Mathematics and Physics

A process of building 3D models from images

Authors: Bui, The Duy
Ma, Thi ChauKeywords: 3D models;3D data;Preprocessing;Matching;Depth RecoveryIssue Date: 2007Publisher: H. : ĐHQGHNSeries/Report no.: Vol. 23;No. 1 (2007)Abstract: Recently, a number of new technologies to capture 3D data have been developed. The application potential of 3D models is enormous, such as, in education, entertaiment, medicine, etc. In this paper, we present our work toward creating 3D model of free form objects from pair of images. We use the basic process of building 3D models proposed in Multiple View Geometry in Computer Vision by Richard Harlley and Andrew Zisserman which includes three main phases: Preprocessing, Matching, Depth RecoveryDescription: p. 9-14URI: http://repository.vnu.edu.vn/handle/VNU_123/57476ISSN: 2588-1124Appears in Collections:Mathematics and Physics

Restoration of machine-components wear resistance

Authors: V.P., Ivanov
A.P., KastriukKeywords: restoration;wear;wear resistance;coatingsIssue Date: 2011Publisher: H. : ĐHQGHNSeries/Report no.: Vol. 27;No. 1 (2011)Abstract: The research relevance is conditioned by the fact that wearing of friction surfaces is determines their limiting state. The content of the process of components wear resistance reduction due to the choice of material composition for restoring coatings, the subsequent mechanical and thermal treatment.Description: p. 29-35URI: http://repository.vnu.edu.vn/handle/VNU_123/56492ISSN: 2588-1124Appears in Collections:Mathematics and Physics

Standard quality support in technical equipment repair

Authors: A.P., Kastriuk
V.P., IvanovKeywords: repair;quality;criteria;quality systemIssue Date: 2011Publisher: H. : ĐHQGHNSeries/Report no.: Vol. 27;No. 1 (2011)Abstract: The necessity for technical equipment repair and its economic effrciency is substantiated. The quality of technical equipment repair is assessed on the basis of technological (manufacturing) criteria that are provided at machinery repair, and on the basis of performance (consumer) criteria that are displayed at machinery usage. The necessity and means for improving the quality of technical equipment repair on the basis of the experience of development and introduction ofthe quality system for rhachinery repair are shown.Description: p. 37 -44URI: http://repository.vnu.edu.vn/handle/VNU_123/56499ISSN: 2588-1124Appears in Collections:Mathematics and Physics

Polyamorphism and Structural Transformation in Liquid B2O3 under Compression: Insight from Visualization of Molecular Dynamics Data

Authors: Mai, Thi Lan
Nguyen, Thu Nhan
Nguyen, Van HongKeywords: Polyamorphism;molecular dynamics simulation;B2O3;structureIssue Date: 2014Publisher: H. : ĐHQGHNSeries/Report no.: Vol. 30;No. 1 (2014)Abstract: The structural order, polyamorphism and structural change of liquid B2O3 at 3000 K and in a 0-40 GPa pressure range are investigated by molecular dynamics simulation. Results show that the network structure of liquid B2O3 is formed from BOx basic structural units (x=3, 4). At ambient pressure, most of basic structural units (coordination units) are BO3 (over 99%). The BO3 basic structural units are linked each to other via OB2 linkages. At high pressure, the network structure of liquid B2O3 comprises of both BO3 and BO4 units linked each to other via OB2 or OB3 linkages. The bond angle and bond length distribution in BOx units is not dependent of pressure. In other word, the topology structure of BOx units in different models is identical. The bond angle distribution in…

Response’s Probabilistic Characteristics of a Duffing Oscillator under Harmonic and Random Excitations

Authors: Nguyen, Dong Anh
Duong, Ngoc Hao
Zakovorotny, V.L.Keywords: Duffing;averaging method;equivalent linearization;harmonic excitation;random excitationIssue Date: 2014Publisher: H. : ĐHQGHNSeries/Report no.: Vol. 30;No. 1 (2014)Abstract: Response’s probabilistic characteristics of a Duffing oscillator subjected to combined harmonic and random excitations are investigated by a technique combining the stochastic averaging method and the equivalent linearization method. The harmonic excitation frequency is taken to be in the neighborhood of the system’s natural frequency. The original equation is averaged by the stochastic averaging method in Cartesian coordinates. Then the equivalent linearization method is applied to the nonlinear averaged equations so that the equations obtained can be solved exactly by the technique of auxiliary function. The theoretical analyses of Duffing oscillator are validated by numerical simulation.Description: p. 39-49URI: http://repository.vnu.e…