ORCID Profile
0000-0003-4725-959X
Current Organisations
Chongqing University
,
School of Resources and Safety Engineering, Chongqing University
,
State Key Laboratory of Coal Mine Disaster Dynamics and Control, Chongqing University
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Publisher: Hindawi Limited
Date: 31-10-2019
DOI: 10.1155/2019/7612805
Abstract: Sintering is an important approach for the alloying of different metals, which is affected by factors such as temperature, grain size, and material properties. And it represents a complex thermodynamic process. This paper had adopted the molecular dynamics methods to investigate the evolution process of nanostructure during the sintering of Cu and Au nanoparticles. The changes in crystalline during the nanosintering process were observed, and the radial distribution function of atoms, the shrinkage ratio, and the sintering neck of the systems were discussed. The initial sintering temperature and melting temperature of the system were obtained at the same time, the characteristics of the sintering neck with changes in temperature during the nanosintering process were revealed.
Publisher: MDPI AG
Date: 09-05-2019
DOI: 10.3390/IJMS20092305
Abstract: The study of changes in the related mechanical property and microscopic structure of methane hydrate during the decomposition process are of vital significance to its exploitation and comprehensive utilization. This paper had employed the molecular dynamics (MD) method to investigate the influence of defects on the microscopic structure and mechanical property of the sI methane hydrate system, and to discover the mechanical property for the defect-containing hydrate system to maintain its brittle materials. Moreover, the stress-strain curve of each system was analyzed, and it was discovered that the presence of certain defects in the methane hydrate could promote its mechanical property however, the system mechanical property would be reduced when the defects had reached a certain degree (particle deletion rate of 9.02% in this study). Besides, the microscopic structures of the sI methane hydrate before and after failure were analyzed using the F3 order parameter value method, and it was found that the F3 order parameters near the crack would be subject to great fluctuations at the time of failure of the hydrate structure. The phenomenon and conclusions drawn in this study provide a basis for the study of the microscopic structure and mechanical characteristics of methane hydrate.
Publisher: Springer Science and Business Media LLC
Date: 05-03-2021
Publisher: Springer Science and Business Media LLC
Date: 02-09-2022
Publisher: MDPI AG
Date: 21-02-2019
DOI: 10.3390/MET9020259
Abstract: The surface properties of coatings during deposition are strongly influenced by temperature, particle fluxes, and compositions. In addition, the precursor incident energy also affects the surface properties of coatings during sputtering. The atomistic processes associated with the microstructure of coatings and the surface morphological evolution during sputtering are difficult to observe. Thus, in the present study, molecular dynamics simulation was employed to investigate the surface properties of Au/Cu alloy coatings (Cu substrate sputtering by Au atoms) with different incident energies (0.15 eV, 0.3 eV, 0.6 eV). Subsequently, the sputtering depth of the Au atoms, the particle distribution of the Au/Cu alloy coating system, the radial distribution function of particles in the coatings, the mean square displacement of the Cu atoms in the substrate, and the roughness of the coatings were analyzed. Results showed that the crystal structure and the sputtering depth of Au atoms were hardly influenced by the incident energy, and the incident energy had little impact on the motion of deep-lying atoms in the substrate. However, higher incident energy resulted in higher surface temperature of coatings, and more Au atoms existed in the coherent interface. Moreover, it strengthened the motion of Cu atoms and reduced the surface roughness. Therefore, the crystal structure of coatings and the motions of deep-lying atoms in the substrate are not influenced by the incident energy. However, the increase in incident energy will enhance the combination of coatings and the base while optimizing the surface structure.
Publisher: World Scientific Pub Co Pte Ltd
Date: 11-09-2020
DOI: 10.1142/S0217984921500019
Abstract: This paper investigates the effects of interparticle distance and heating rate on the aggregation characteristics of Cu/Au nanoparticles using molecular dynamics (MD) simulations, and focuses on discussing the effects of the two above-mentioned factors on the entire system. Our results suggested that the reduction in heating rate and increasing the initial distance of the particles would both contribute to raising the initial sintering temperature. However, when the particles’ initial distance was greater than the cut-off radius of the system, the initial sintering temperature was not increased any longer, but fluctuated within a certain range. Furthermore, the sintering force of the nanoparticles at the initial sintering temperature was investigated, and it was found that the heating rate made no obvious difference to it. Nonetheless, the sintering force varied under different initial distance of the particles (at the same heating rate) due to system energy changes.
Publisher: Springer Science and Business Media LLC
Date: 24-10-2021
Publisher: Hindawi Limited
Date: 31-03-2020
DOI: 10.1155/2020/1018369
Publisher: World Scientific Pub Co Pte Lt
Date: 06-06-2020
DOI: 10.1142/S0217984920502802
Abstract: The droplet coalescence phenomenon extensively exists in the industrial production and application, as well as in nature, which is of great research significance. This paper adopted the molecular dynamics (MDs) simulation method to investigate the behavioral characteristics of water/water, ethanol/ethanol and water/ethanol nanodroplets coalescence. The results suggested that, in water and ethanol nanodroplet coalescence process within the water/ethanol system, ethanol was always wrapped on the outer layer of water droplets. The droplet shrinkage in the water/water system was greater than those in the other two systems meanwhile, that in the water/ethanol system rapidly increased after the contact of droplets, and subsequently surpassed that in the ethanol/ethanol system.
Publisher: Hindawi Limited
Date: 2014
DOI: 10.1155/2014/328902
Abstract: With the development of mine industry, tailings storage facility (TSF), as the important facility of mining, has attracted increasing attention for its safety problems. However, the problems of low accuracy and slow operation rate often occur in current TSF safety evaluation models. This paper establishes a reasonable TSF safety evaluation index system and puts forward a new TSF safety evaluation model by combining the theories for the analytic hierarchy process (AHP) and improved back-propagation (BP) neural network algorithm. The varying proportions of cross validation were calculated, demonstrating that this method has better evaluation performance with higher learning efficiency and faster convergence speed and avoids the oscillation in the training process in traditional BP neural network method and other primary neural network methods. The entire analysis shows the combination of the two methods increases the accuracy and reliability of the safety evaluation, and it can be well applied in the TSF safety evaluation.
Publisher: Hindawi Limited
Date: 16-06-2019
DOI: 10.1155/2019/5154173
Abstract: In the process of adsorption and separation of fluid molecules on the solid surface of porous nanomaterials, the mutual transformation of thermal energy and surface energy can improve the heat absorption and energy utilization efficiency of circulating working medium. In this study, the adsorption, thermal energy storage, and mean square displacement of the minimum energy adsorption configuration of R1234ze in UIO-66 were studied by molecular simulations, including molecular dynamics (MD) and grand canonical Monte Carlo (GCMC) simulations. The results show that the thermal energy storage density of R1234ze/UIO-66 mixed working medium is significantly higher than that of pure working medium in the temperature range of 20 K-140 K. However, the increase rate of thermal energy storage density decreases significantly as temperature rises, and the mean square displacement and diffusion coefficient increase with increasing temperature.
Publisher: Springer Science and Business Media LLC
Date: 11-03-2020
Publisher: American Chemical Society (ACS)
Date: 10-09-2021
Publisher: World Scientific Pub Co Pte Lt
Date: 12-03-2020
DOI: 10.1142/S0217979220500496
Abstract: Particle coalescence has wide applications in nature and industry. In this study, molecular dynamics (MDs) simulations were employed to examine the sintering of Cu and Au nanoparticles, as well as two other systems, namely, Cu nanoparticles and Au nanoparticles. The results suggested that, the Au atoms diffused through the outer area of the sintering neck before the nanoparticles were fused into one sphere. The possible reason was that the Au atoms resembled fluid, which could be ascribed to the local thermal energy at the contact area. Typically, the change in energy per atom from 300 K to the contact temperature denoted that less energy was required for the atoms in the pure Cu system to contact with each other than those in the other two systems.
Publisher: Walter de Gruyter GmbH
Date: 20-02-2020
Abstract: Molecular dynamics (MD) analysis of methane hydrate is important for the application of methane hydrate technology. This study investigated the microstructure changes of sI methane hydrate and the laws of stress–strain evolution under the condition of compression and tension by using MD simulation. This study further explored the mechanical property and stability of sI methane hydrate under different stress states. Results showed that tensile and compressive failures produced an obvious size effect under a certain condition. At low temperature and high pressure, most of the clathrate hydrate maintained a stable structure in the tensile fracture process, during which only a small amount of unstable methane broke the structure, thereby, presenting a free-motion state. The methane hydrate cracked when the system reached the maximum stress in the loading process, in which the maximum compressive stress is larger than the tensile stress under the same experimental condition. This study provides a basis for understanding the microscopic stress characteristics of methane hydrate.
Publisher: MDPI AG
Date: 24-12-2020
DOI: 10.3390/W13010015
Abstract: A portion of the accumulated tailings in a tailings pond exhibits an unsaturated state. The mechanical properties of unsaturated tailings affect the safety and stability of tailings dams. To investigate the effect of moisture content on the deformation characteristics of unsaturated tailings in the mesoscale, a special testing apparatus is applied to experimentally study the settlement deformation and mesostructure evolution of unsaturated tailings under continuous load. The results show that the mesostructure deformation of unsaturated tailings with different moisture contents under load is the same and can be ided into four stages: pore compression, elastic deformation, structure change, and further compaction. However, the critical pressures of the four stages are significantly different there is an optimal moisture content corresponding to the maximum deformation resistance. Moreover, the influence of the liquid bridge regime on the mesostructure deformation of unsaturated tailings is discussed in this paper.
Publisher: MDPI AG
Date: 14-11-2019
DOI: 10.3390/W11112388
Abstract: Tailings ponds are the indispensable facilities in the mine production and operation. Once the dam is destabilized and damaged, it will pose a serious threat on the life and property of the downstream population and could also potentially cause an environmental disaster. With an engineering background, this paper dynamically and numerically simulates the evolution process of tailings flow from dam failure and the influence scope of any resulting disaster in context. The evolution characteristics of leaked tailings flow are analyzed at various downstream riverbed slopes and debris blocking dam settings. In addition, parameters such as flow rate, impact force and deposition range of leaked tailings flow at downstream arrival are studied, as well as their correlations. The results indicate that the flat terrains upstream and downstream of passage zone show a relatively larger area of inundation by tailings flow. Both the maximum and final downstream inundated ranges increase with the elevating slope of downstream riverbed, and the leaked tailings are deposited mainly in the nearby villages in front of the dam and the flat terrains of the downstream passage zone. Additionally, rational establishment of debris blocking dams on the downstream side is effective in diminishing the damage of tailings flow to the downstream section. This study can also provide an important basis for the quantitative evaluation of post-disaster influence scope for tailings pond as well as for the design of dam body.
Publisher: Elsevier BV
Date: 12-2022
Publisher: Springer Science and Business Media LLC
Date: 29-04-2020
DOI: 10.1038/S41598-020-64187-X
Abstract: The refrigerant circulation heat can be enhanced through the mutual transformation between thermal energy and surface energy during the adsorption and separation process of fluid molecules in porous materials. In this paper, the adsorption and energy storage of R1234ze(z), R1234yf, R32 and R134a, as well as their mixed refrigerants in Mg-MOF-74 and Ni-MOF-74 nanoparticles were investigated by means of molecular dynamics simulations and grand canonical Monte Carlo simulations. The results suggested that, in the case of pure refrigerant adsorption, the adsorption quantities of R32 and R134a in MOFs were higher than those of R1234yf and R1234ze(z). However, in the case of saturation adsorption, the desorption heat of R32 was lower than that of R1234yf and R1234ze(z). The addition of MOF-74 nanoparticles (NPs) could enhance the energy storage capacity of the pure refrigerant besides, R1234yf and R1234ze(z) nanofluids had superior enhancement effect to that of R32 nanofluid. In mixed refrigerant adsorption, the adsorption quantities of R1234ze(z) and R1234yf were lower than those of R32 and R134a with the increase in temperature, the adsorption of R1234ze(z) and R1234yf showed a gradually increasing trend, while that of R32 was gradually decreased.
Publisher: Springer Science and Business Media LLC
Date: 12-2015
Publisher: American Chemical Society (ACS)
Date: 14-01-2021
Location: China
Location: China
No related grants have been discovered for Sen Tian.