Papers by Keyword: Computer Simulation

Abstract: The computer simulation of the structural evolutions of Al nanowires on cooling has been carried out based on the embedded atom method potential. The infinite Al nanowire was modeled by super-cell with a one-dimensionally periodical boundary condition along the [001] direction. The simulation results indicate that the microstructure of Al nanowires changed from amorphous to helical multi-shelled structure along with the drops of cooling rate. The helical multi-shelled structure possesses some features of amorphous structure, but it is more stable than the later. Moreover, the Al nanowires still keep the helical multi-shelled structure even if the cooling rate decreased to 1010 K/s.

Abstract: Magnetic fluid is a stable colloidal dispersion of ferromagnetic particles in a liquid carrier. Once a magnetic field is applied to magnetic fluids (MF), various structures of MF are formed. A detailed understanding of structures and particle distributions in gradient magnetic fields is much important. But very few works have been done on this. In the present study, the effects of magnetic field gradient and magnetic interaction among magnetic particles on the structures of MF are investigated using a two-dimensional Monte Carlo simulation. The results show that a gradient distribution of magnetic particles is formed under gradient magnetic fields. However, as the interaction between magnetic particles increases, the distribution gradient decreases, accompanied by the formation of chain-like clusters. Moreover, with increasing the magnetic interaction, particle distribution changes from grass-like clusters to needle-like ones.

Abstract: Molecularly imprinted polymer microspheres for selective binding and recognition of atenolol were prepared by means of precipitation polymerization method using methacylic acid as functional monomer and trimethylolpropane trimethacrylate as cross-linker in the presence of atenolol as template molecule in acetonitrile solution. Computer simulation was employed to demonstrate the mechanism of the interaction between methacylic acid and atenolol. The scanning electron microscopy exhibited that the polymers were uniform spheres with the diameter of about 0.6µm. The adsorption properties of atenolol for imprinted microspheres were evaluated by equilibrium rebinding experiments. Scatchard plot analysis revealed that there were two classes of binding sites in the imprinted microspheres. The dissociation constant and the apparent maximum binding capacity were 4.56×10-4mol/L and 186.46μmol/g for the high affinity binding sites, 2.40×10-2mol/L and 4.01mmol/g for the low affinity binding sites. Compared to the structrally analogues, the imprinted microspheres exhibited a high selective reconizable capacity towards the template.

Abstract: In this study, the influence of pulling velocity on temperature field, fluid field and grain structure of a unidirectionally solidified superalloy DZ417G cylindrical casting was investigated by using a 3D cellular automaton finite element (CAFE) model within commercial software CALCOSOFT. The predictions show that temperature distribution in the casting is well in accordance with the experiment result. The solidification front and fluid field are sensitive to changes in pulling velocity. And the pulling velocity should be controlled less than 0.5 mm/s in our experiment so as to effectively decrease the grain number and mean grain deviation.

Abstract: A two-dimensional cellular automaton model is developed to simulate the isothermal hot compression phase transformation of β→α in TA15 titanium alloy. The model, based on the data of hot compression deformation and some assumption, the phase transformation nucleation and growth function of the phase β→α which is utilized by the automaton in a probabilistic fashion. The probability of nucleation and growth of α phase is confirmed and described by the existing theories of dislocation density. The competition between phase transformation and growth of transitional phase is described by the changes of dislocation density in this cellular automaton lattice. Based on the results of cellular automaton, the transformation fraction of α phase is calculated with the number of lattice and isothermal phase transformation kinetic equation is also calculated with data of transformation fraction, and the effect of hot compression deformation parameters on phase transformation is also discussed.

Abstract: The intensity distribution of a UV linear light source and a UV linear light with a parabolic cylinder reflector on work piece surface were simulated using OpenGL program based on VC++6.0. Physical models were established and relevant fundamental assumptions were given. The results of the simulation fitted the real situation quite well. It is feasible to adjust the parameters of UV-curing radiation system using the results of computer simulation.

Abstract: A design-analysis and simulation approach of complex ball-end cutter was proposed by using computer graphics and OpenGL control in this paper. The mathematical models of rake face and flank face of a complex ball-end cutter were built as the simulation condition. A computer-aided design and simulation processing system of complex tool was presented through pre-modeling OpenGL control. Some 3D simulation models of complex ball-end cutter including spiral cylinder, ball-head (including rake face, chip groove, first flank face and second flank face) and grinding wheel were created respectively. According to mathematical models and VC++ software platform, transformation and machining animation simulations of ball-end cutter were designed and realized visually using OpenGL control interface technique. The results of Three-dimensional design and simulation will offer sufficient theory foundation for virtually manufacturing ball-end cutter.

Abstract: Masonry walls resist most of the lateral loads in some Chinese historical architecture. To investigate the seismic properties of these load-bearing masonry walls, blocks in a typical Chinese old building undergoing retrofit are reserved. Compressive test specimens and wall panel specimens are constructed using these blocks and lime mortar. Mixing of the lime mortar is similar to that used in the old building. Material tests and pseudo-static tests are then performed. The damage modes and hysteretic curves of the wall panel specimens are studied. The test results are expanded through computer simulation. Some characteristics of the load-bearing masonry walls are summarized based on the test and simulation results. The proposed methodology and results can be referred to in further researches on seismic properties of historical masonry architectures.

Abstract: A sequential numerical method for characterization of hardening performance of quenchants applied for steel quenching is outlined here. This novel method is based on the specific processing of measured time–temperature samples performed as a result of cooling curve tests. The heat transfer coefficient, as a function of surface temperature, characterises the heat transfer during cooling and is calculated using an iterative inverse algorithm. The heat transfer coefficient is used for calculation of the microstructural constituents and the hardness profile of cylindrical samples of arbitrary diameters. The hardening performance of the media is evaluated by the estimated hardness of the specimen obtained by heat treatment.

Abstract: In light of the characteristics of transit passenger’s route choice behavior, this paper introduces a multi-agent based simulation approach into the study of this behavior.At first, the paper analyzes factors affecting transit passenger’s route choice behavior and then studies the rules of behavior for transit passengers when making route choices. The paper further proposes a utility function for selected routes and examines ways to investigate and analyze corresponding data so as to provide a basis for the modeling of passenger agent’s route choice behavior. Following this, the paper builds up a simulation system for transit passenger’s route choice behavior based on the multi-agent simulation software Starlogo developed by Massachusetts Institute of Technology (MIT), and explains the process that will actually take place when using the simulation system. Finally, inadequacies of the study are analyzed and the focus of further research is indicated.