Vol 20, No 4 (2016)

This paper describes the model NMSSM with effective explicit and spontaneous CP-violations, and additional mixing of CP-even and CP-odd Higgs bosons states. The neutral Higgs bosons masses and decay widths were calculated at fixed parameters of the model so one of the physical states is responsible the results of the LHC experiments. The calculation of decay widths produced in the one-loop approximation in the framework of the quantum field perturbation theory. We defined two scenarios for observables. The first scenario corresponds to the set of parameters leading to the lightest Higgs boson mass of 125 GeV. The second one with the restriction on the Higgs boson mass implemented in the electroweak baryogenesis, which leads to the experimental data agreement with the second physical mass condition.

A problem of the Lie point approximate symmetry group classification of a perturbed subdiffusion equation with a small parameter is solved. The classification is performed with respect to anomalous diffusion coefficient which is considered as a function of an independent variable. The perturbed subdiffusion equation is derived from a fractional subdiffusion equation with the Riemann-Liouville time-fractional derivative under an assumption that the order of fractional differentiation is close to unity. As it is follow from the classification results, the perturbed subdiffusion equation admits a more general Lie point symmetry group than the initial fractional subdiffusion equation. The obtained results permit to construct approximate invariant solutions for the perturbed subdiffusion equation corresponding to different functions of the anomalous diffusion coefficient. These solutions will also be the approximate solutions of the initial fractional subdiffusion equation.

The uniqueness and existence of solutions of a nonlocal problem proved for an equation of mixed type. This equation contains diffusion equation of fractional order. The boundary condition contains a linear combination of generalized operators of fractional order with the Gauss hypergeometric function. The solution of the problem is given explicitly.

In this work we have developed energy balance model for inelastic deformation process of metals. Changes in the material structure are taking into account with the help of tensorial variable having the physical meaning of additional strain induced by initiation of defects. Introduction of such a parameter allows one to calculate the stored energy value and develop an energy-based fracture criterion. There were considered two ways of derivation of constitutive equations for plastic and structural strain. The first method was based on the principles of linear nonequilibrium thermodynamics, the second one is the analogue of the flow plastisity theory. Developed thermomechanical model includes equilibrium equation, geometric relation for strain tensor, Hooke’s law, constitutive equations for structural and plastic strain and energy balance equation. It is assumed that fracture in the material takes place when stored energy reaches critical value in some volume of the material. The application of such an approach to fracture problems of the metals is illustrated by two numerical examples. The first example is crack path simulation in the steel shaft with initial crack oriented at the certain angle to the shaft axis. The second example is simulation of the crack initiation and propagation in the steel bearing bracket. The obtained results are in agreement with the previously published results and could be used for simulation of fracture of real structures.

We considere and analyze the uniaxial phenomenological models of viscoelastic deformation based on fractional analogues of Scott Blair, Voigt, Maxwell, Kelvin and Zener rheological models. Analytical solutions of the corresponding differential equations are obtained with fractional Riemann-Liouville operators under constant stress with further unloading, that are written by the generalized (two-parameter) fractional exponential function and contains from two to four parameters depending on the type of model. A method for identifying the model parameters based on the background information for the experimental creep curves with constant stresses was developed. Nonlinear problem of parametric identification is solved by two-step iterative method. The first stage uses the characteristic data points diagrams and features in the behavior of the models under unrestricted growth of time and the initial approximation of parameters are determined. At the second stage, the refinement of these parameters by coordinate descent (the Hooke-Jeeves’s method) and minimizing the functional standard deviation for calculated and experimental values is made. Method of identification is realized for all the considered models on the basis of the known experimental data uniaxial viscoelastic deformation of Polyvinylchloride Elastron at a temperature of 20 ℃ and five the tensile stress levels. Table-valued parameters for all models are given. The errors analysis of constructed phenomenological models is made to experimental data over the entire ensemble of curves viscoelastic deformation. It was found that the approximation errors for the Scott Blair fractional model is 14.17 %, for the Voigt fractional model is 11.13 %, for the Maxvell fractional model is 13.02 %, for the Kelvin fractional model 10.56 %, for the Zener fractional model is 11.06 %. The graphs of the calculated and experimental dependences of viscoelastic deformation of Polyvinylchloride Elastron are submitted.

This article focuses on the modification of the block option Gauss-Seidel method for normal systems of equations, which is a sufficiently effective method of solving generally overdetermined, systems of linear algebraic equations of high dimensionality. The main disadvantage of methods based on normal equations systems is the fact that the condition number of the normal system is equal to the square of the condition number of the original problem. This fact has a negative impact on the rate of convergence of iterative methods based on normal equations systems. To increase the speed of convergence of iterative methods based on normal equations systems, for solving ill-conditioned problems currently different preconditioners options are used that reduce the condition number of the original system of equations. However, universal preconditioner for all applications does not exist. One of the effective approaches that improve the speed of convergence of the iterative Gauss-Seidel method for normal systems of equations, is to use its version of the block. The disadvantage of the block Gauss-Seidel method for production systems is the fact that it is necessary to calculate the pseudoinverse matrix for each iteration. We know that finding the pseudoinverse is a difficult computational procedure. In this paper, we propose a procedure to replace the matrix pseudo-solutions to the problem of normal systems of equations by Cholesky. Normal equations arising at each iteration of Gauss-Seidel method, have a relatively low dimension compared to the original system. The results of numerical experimentation demonstrating the effectiveness of the proposed approach are given.

A non-convex problem of mathematical programming is considered, which permissible region is a simplex. A two-stage algorithm is proposed for approximate solution of the problem. The region of global optimum is determined using the Ψ-transform method at the first stage; local “fine-tuning” of the solution is performed at the second stage. The Ψ-transform was modified taking into account the special features of the problem under consideration. Ψ-function is determined according to the results of statistical tests implemented using the generator of random points uniformly distributed over the simplex. The proposed method of reflection of regular simplexes is used for fine-tuning of the solution. An example of application of the developed algorithm for solving the problem of optimization of component composition of the hydrocarbon mixture is presented.