Papers by Keyword: Coordination Number

Abstract: The article discusses the application of the discrete element method (DEM) for modeling the behavior of spherical particles in granular media. Key aspects of particle contact interactions, including frictional forces, elasticity, coordination number, and the shape factor of spherical particles, are analyzed and investigated. It is worth noting that the proposed methodology enables the study of the mechanical properties of systems with particles of various sizes and compositions, as well as the modeling of their behavior in confined spaces and under dynamic influences. The modeling results demonstrate the high accuracy and versatility of the DEM for analyzing processes in bulk materials, particularly transportation, mixing, and granulation. The findings underscore the effectiveness of using DEM to solve complex problems and highlight prospects for its further improvement.

Abstract: This article examines the main problems of modelling spherical (circular) particles. The main method of the initial process of filling lobules using the Cauchy and Reynolds problem is substantiated. An image of an object-oriented complex of free fall of a spherical particle and their many non-collision spheres is presented. Based on the obtained research results, the main parameters of the process of filling particles of heterogeneous materials. An example of visualization of the developed software product for filling material particles is given, taking into account a number of cross-sections of a cylindrical hopper in height. A histogram of the distribution of material particles from porosity over the volume of a cylindrical hopper is also constructed.

Abstract: The effect of different additives Ni, Fe, Cu on the structure and properties of electrolyte system 78% Na₃AlF₆- -9.5%AlF₃-5.0%CaF₂-7.5%Al₂O₃ at 1200K and 1.01Mpa was studied by molecular dynamics method. The radial distribution function, coordination number, diffusion coefficient, conductivity, and viscosity of the system were discussed in detail. The results demonstrated that the order of the self-diffusion coefficient of ions in the electrolyte system is: Na⁺ > F^- > O^2- > Ca²⁺ >Al³⁺. The addition of Ni and Fe connected the free aluminum composite ion groups in the system through fluorine bridges, which enhanced the interaction between Al³⁺ and Al³⁺. The addition of Cu weakened the interaction between Al^{3 +} and Al³⁺ and the F^-. The interaction between Al³⁺ and Na⁺, [AlF₇]^4- ionic groups might appeared in the melt system. After adding NiO, Fe₂O₃, and Cu, the electrical conductivity of the system increased, and the viscosity decreased. The research work revealed the influence of Ni, Fe, Cu on the ion existence form, mobility, inter-ion interaction and diffusion mechanism of cryolite molten salt system, which has important guiding significance for aluminum electrolysis production.

Abstract: We present the calculation of structural properties for liquid Ga at different temperatures using pseudopotential theory. The temperature dependence of structure factor has been determined using the hard-sphere Percus-Yevick approximation which is characterized by single parameter hard sphere diameter or equivalently packing fraction. The temperature dependent hard-sphere diameter σ (T) is estimated using criterion from the calculated effective pair potential. The modified empty-core pseudopotential due to Hasegawa et al. (J. Non-Cryst. Solids. 117/118 (1990) 300), which is valid for all electrons and contains the repulsive delta function to achieve the necessary s-pseudisation is used for electron–ion interaction. The temperature effects have been studied via dimensionless damping term and potential parameter in the pair potential. Finally, the predicted results for structure factor, pair correlation function and coordination numbers have been compared with recent available data, and a good agreement has been achieved.

Abstract: This paper summarize idealized theoretical studies of bicomponent particle packing parameters, affecting the phase and pore structure of obtained materials. Such a kind of analysis can be used both in theoretical consideration of material engineering problems and in chemical industry. The effects of key variables on the relationship between packing fraction and particle size were re-examined for general application. Potential applications of these results include synthesis of nanopaterials, adsorbents, catalyst carriers and packing for chromatographic columns. Directions for future research are suggested.

Abstract: Through computer aided design, manufacturing and evaluation, various ceramics dendrites with spatially ordered micro cavities were successfully fabricated by utilizing stereolithography. Micrometer order ceramic lattices were propagated spatially in computer graphic space. Ceramics nanoparticles were dispersed in to photo sensitive liquid resins to obtain thixotropic slurries. The paste material was spread on a grass substrate by using a mechanical knife edge, and an ultra violet micro pattern was exposed to create cross sectional solid layer. After the layer stacking process, the obtained composite precursor was dewaxed and sintered in an air atmosphere. By the micro patterning stereolithography, solid electrolyte dendrites of yttria stabilized zirconia with spatially ordered porous structures were fabricated for fuel cell miniaturizations. Gaseous fluid profiles and pressure distributions in the formed ceramic lattices with various porosity percent were visualized and analyzed by a finite element method. Subsequently, alumina micro photonic crystals with a diamond lattice structure were fabricated. Electromagnetic wave properties were measured by using a terahertz time domain spectroscopy. A complete photonic band gap was exhibited, and a localized mode to select the wavelength was obtained by introducing a defect cavity.

Abstract: It is specified an interrelation between thermal effects in metals phase transformations and changes in structural parameters (coordination number) of the initial and new phases. It is offered the analytical dependences for calculation of the binding energy and atoms coordination numbers, the metals heat of formation, temperature and thermal effects of phase transitions in metals. It is analyzed the energy parameters of the Periodic System elements considering the type of their crystal lattices. By calculation it is estimated structural parameters of liquid and solid phases, thermal effects and the evaporation temperature of crystallization and polymorphic transformation, and energy formation for 55 elements, for which the literature contains reliable experimental data.

Abstract: A model of the process of gypsum optimal structure formation has been designed with the application of computer simulation methods. An optimal raw mix speciation and gypsum specimen strength top values corresponding to the model were experimentally obtained and recorded.

Abstract: The intrinsic complexity of granular materials stems from the fact that the characterizing variables at the micro-scale and the macro-scale are of different nature. Macroscopically, tensorial variables (stress tensor, strain tensor, fabric tensor) are commonly used based on Representative Volume Element (RVE), while vectorial variables (contact force, contact displacement, contact normal) are adopted at particle-scale. This paper mainly discusses some basic characterizations for these two scales, as well as their correlations. Numerical simulations using Discrete Element Method (DEM) are then conducted to show the evolutions of both microscopic and macroscopic variables during monotonic loading. It is indicated that the particle reorientations in the dense sample are much more pronounced than that in the loose one during shearing.