Papers by Keyword: Structure Factor

Abstract: The partial structure factors for liquid alloy In_1-xSn_x have been computed at varying concentration and temperatures using pseudopotential theory. The structure factor S(q) and pair correlation function g (r) have been determined using the hard-sphere approximation. The temperature dependent hard-sphere diameter σ (T) is estimated using Vσ=Vminr+12kBT criterion from the computed pair potential. The modified empty-core local pseudopotential, which represents the orthogonalisation effect due to s-core states, is used for electron–ion interaction with proper screening function. The only potential parameter, the core radius, is determined at different temperatures from the knowledge of structure factor. Intrinsic temperature effects have been studied through dimensionless damping term (see formula in paper) in the pair potential. The effect of temperature and concentration on structure factors is discussed to shed light on bonding in technologically important alloy. This used pseudopotential proved successful in explaining the structural properties of non-crystalline alloys at higher temperatures.

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: We present the theoretical study of the magnetic and thermodynamic properties for the systems with anisotropic magnetic units and results of computer simulations. We focus our attention on the theoretical description of the initial susceptibly and structure factor. An extensive comparison of our theoretical model to the results of molecular dynamics simulations for a wide range of system parameters demonstrated good quantitative and qualitative agreement. As a result, we can say that the macroscopic responses of the systems drastically change with the anisotropy of the microstructural units.

Abstract: Two different bidisperse approximations of one gamma-distribution were examined in the present manuscript. The bidisperse system was chosen as the first step to allow for polydispersity when studying thermodynamics and microstructure of magnetic fluids. The author used the first-order modified mean-field model for investigating magnetization curves for these approximations and showed that curves are almost identical. Also analyzed was the influence of choosing variant of constructed bidisperse model on the structure factors, which were constructed using the mathematical model, developed in the paper by Novak et al. [J.Chem.Phys. 139 (2013) 224905].

Abstract: The structure properties of a ferrofluid modeled by a bidisperse system of dipolar hardspheres are studied theoretically for the case of zero external field. Analytical expressions are providedfor the pair distribution function (PDF) and structure factor (SF) to within the first order in numberdensity and the second order in dipole-dipole interaction strength. The influence of the granulometriccomposition on the behavior of the PDF and the position of the first peak of the SF is analyzed.

Abstract: Flexure hinge has been widely used in high precision micro-positioning mechanism and the most common type is right circular flexure hinge. Firstly, asymmetrical right circular flexure hinge is presented and the structure factor is introduced in the paper according to the size of the cutting arc radius of both sides of right circular flexure hinge. Then, asymmetrical right circular flexure hinge is classified by the value of structure factor. Finally, the analytical expression of rotation stiffness for asymmetrical right circular flexure hinge is deduced, and the relationships between the structure factor and rotation stiffness are calculated with Matlab software. The analytic result has an important significance to design flexure hinge.

Abstract: This article has introduced and evaluated the various methods of study on carbon emissions, and makes a comparison on the research conclusion by using these methods. We has classified the influence factors of carbon emissions into three primary factors such as technical factor, structure factor and scale factor, respectively including six secondary factors such as carbon emission intensity and energy intensity; energy structure and industrial structure; economic scale, population size.

Abstract: The mixing-extruding machine is made up of mixer and unconventional double-cone screw extruder, which has both the excellent mixing capabilities and the continuous extruding characters. In the mixer chamber, the complex mixing motion of the blends is determined by the different kinds of forces acting on the blends. The different structure of the rotor, the distribution of the three direction forces is changed also。From the force analysis about the blends, there are three structure factors about rotor effecting the mixing process, such as the wedge angle θ of the rotor’s cross-section, the helix angle β of the rotor’s wing and the length of the wings. The best value of each structure factor can be gotten from theoretical analysis.

Abstract: From the theoretical point of view, characterization of nano particle interaction depends much on the particle diameter , packing factor , the parameter of the Lennard-Jonnes (LJ) pair potential function  (r) and static structure factor S (Q). A novel method suggested in this paper has been tested on seven specific drug delivering fluorocarbons by estimating the strength of interaction /k of  (r) and S(Q) in terms of the elementary parameter . The importance of this paper is that, the input parameter viz., packing factor has been obtained from the experimental ultrasonic velocity of those seven systems. Calculations were extended for different temperatures involving four different equations of states to back up the application of the model. Though there is a lack of analytical results to compare, our predictions are encouraging.

Abstract: An evolution of the structure of three glasses of Na2O-Nb2O5-SiO2 system in the course of isothermal heat treatments at 660–700°C and the extinction coefficient of the material were studied. Spinodal phase separation was found to be a primary process followed by precipitation of nano-sized NaNbO3 crystalline phase. It was found that the spectral dependence of the extinction coefficient in the wavelength range λ= 400–800 nm corresponds to light scattering by spinodal structure at the phase separation stage and by independent Rayleigh scatterers (NaNbO3 nanocrystals) at the early stage of crystallization. The extinction coefficient increases at the first half of the crystallization stage and then decreases. At the late stage of crystallization and for the final glass-ceramics, the extinction coefficient α is 10–20 times smaller than that calculated for independently scattering nanocrystals and is characterized by anomalous wavelength dependence (α ∝ λ−6). The model for calculation of extinction coefficient is proposed, in which the interference effects in light scattering by nanocrystals are taken into account. On this basis, the variation of extinction coefficient in the course of crystallization and its wavelength dependence are explained.