Software & Systems

Journal articles №3 2012

51. Parallel algorithms designed for the strength analysis of hydrogen-charged structures [№3 за 2012 год]
Authors: (fedotov@imach.uran.ru) - ; Spevak L.F. (lfs@imach.uran.ru) - Institute of Engineering Science of the Ural Branch of the RAS, Ph.D; Nefedova O.A. (nefedova@imach.uran.ru) - Institute of Engineering Science of the Ural Branch of the RAS;
Abstract: The work provides a model for estimation of hydrogen brittleness for flat elements used in metal structures with defects. It is known that defective metal parts the hydrogen concentration is distributed fairly uneven – defect area is surrounded with molecular hydrogen of high concentration under high pressure. This model can be used for analysis of destruction process of a metal structure that is exposed to intensive external action. In this case, internal pressure in defects grows quickly, and this leads to destruction of such elements. The model uses algorithm of coupled diffusion-deformation problem. Coupled problem includes equations that describe hydrogen diffusion process in high field, and mechanic equations for stress and deformation tensors that consider diffusion process. Solution of deformation problem in linear elasticity theory is made with modified boundary element method. Collection of the hydrogen around defect area is described by convective diffusion in the field of high mechanical stress. Diffusion problem can be solved with modified boundary element method. Solution of the coupled problem can be obtained step by step in time. In final stage of calculation, each step produces value of molecular hydrogen pressure in every defect and then destruction condition of boundaries is checked. For reduction of computing time, parallelizing procedure was performed. The program was designed with this algorithm. This program can be implemented on multiprocessor computing system. This algorithm was illustrated by solution of two-dimensional problem of hydrogen diffusion around the defect – pores for the metal sample exposed to external tension stress. Calculation outputs are shown in charts.
Keywords: analytical integration, modified boundary element method, hydrogen embrittlement, coupled diffusion-deformation problem, parallel computing
Visitors: 9649

52. Parallel design algorithm for description of the mass transfer in a pore [№3 за 2012 год]
Authors: () - ; (que_kola@mail.ru) - ; Koltsova E.M. (kolts@muctr.ru) - D. Mendeleev University of Chemical Technology of Russia (Professor), Ph.D;
Abstract: Here is described a model using molecular dynamics approach that describes gas transfer in small pores. Two types of the mass transfer that happen in a pore were taken into account: Knudsen diffusion and molecular diffusion. Two cases of interaction are mentioned that describe molecular movement and interaction. First case describes the variant, where molecules move according to classic mechanics law and where they interact with each other and a wall, on the principle of perfectly elastic collision. It is assumed that the particles can collide with the pore’s wall in two ways: mirror and diffusion, and for each specific collision this way is defined at random fashion, and the ratio of collisions according to both ways presents one of the features of the model. The second case describes molecular interaction using intermolecular potential of Lennard-Jones interaction. Calculation of molecular movement was made with parallel algorithms. Parallel computing is made with the use of CUDA technology. Information about particle features is stored in 3-D array. Number of array cells corresponds to number of particles in the system. Each array cell contains information about particle: coordinates, velocity vector, speed up vector and its type. One dimension array of particle type exists separately. Number of array elements equals to number of types of existing particles. Cells contain information about each substance that is present in the system: particle’s mass and radius, coefficient of molecular interaction potential. The array was arranged with bubble sort algorithm adapted for parallel operation and extended for 3-D case. The article contains basic computation flow charts.
Keywords: parallel computing, diffusion coefficient, Knudsen diffusion, gas diffusion, molecular dynamics
Visitors: 9208

53. Optimization algorithms of continuous lactic acid biosynthesis [№3 за 2012 год]
Authors: Gordeev L.S. (l.s.gordeev@yandex.ru) - D. Mendeleev University of Chemical Technology of Russian Federation, Ph.D; Gordeeva Yu.L. (l.s.gordeev@yandex.ru) - K.I. Skryabin Moscow State Academy of Veterinary Medicine and Biotechnology, Ph.D; (ivashkin@msaab.ru) - , Ph.D;
Abstract: In the article there are obtained ratios for calculation of continuous lactic acid biosynthesis indicators. The ratios are based on a mathematical model of continuous synthesis in fermenter with agitation. Feature of the model is that each component (substrate, biomass and product) the own expression for specific velocity is written. As the criterion of optimality the productivity Qp on target product (lactic acid) is used. When solving optimal task, at first there are evaluated the channel speed D and the substrate concentration in the output flow, and then the substrate concentration Sf at the inlet of the machine is calculated ensuring maximum productivity. The obtained ratios are used for the development of algorithms of continuous lactic acid biosynthesis optimization. Three variants are considered: absence of limits of the substrate concentration in the incoming flow and the flow value; the maximum possible substrate concentration in the incoming flow and the specified flow value; limit of the flow speed. The second variant is determined by the concentration of the substrate in the incoming stream for optimal conditions, the third is the flow. The second algorithm provides for validation of flow value and the possibility of correction. Numerical results have shown that the greatest value of productivity is achieved for the first variant: Qp=12,42 g/(l h) Sf=46,8 g/l and D=0,5 h-1. Productivity of the second variant: Qp=7,85 g/(l h), Sf=30,39 g/l and D=0,8 h-1. For the third variant: Qp=12,23 g/(l h), Sf=60 g/l and D=0,5 h-1.
Keywords: lactic acid, biosynthesis, optimisation
Visitors: 12269

54. Mathematic model of the user Network-on-Chip [№3 за 2012 год]
Authors: Mosin S.G. (smosin@vpti.vladimir.ru) - Vladimir State University named after Alexander and Nikolay Stoletovs, Ph.D; (dipuuu@gmail.com) - ; (dipuuu@gmail.com) - ;
Abstract: Microelectronics development provided implementation of complex electronic systems in integrated-circuit form. CAD systems, integral technologies and design cycle during design of electronic system are selected to reduce time of their creation, increase reliability and quality of the final product. The effectiveness of the design process can be improved with different approaches, e.g. SoC – system on a chip, SiP – system in a package, MCM – multi chip module etc. For design of complex MPSoC – Multiprocessors System on a Chip it was provided NoC technology – network on a chip. Architectures of specialized MPSoC applications include numerous heterogeneous computing cores and memory modules. Each core provides a limited set of applicable functions. Such projects can be provided with simple inter-core communication. NoC technology is used for design of communication environment that provides communication between different system modules. NoC consists of routers that are physically connected with each other. Each computation core and memory blocks are connected to NoC by means of interface to the network (RNI-interface). In general case, NoC technology suggests the use of homogeneous topology – the grid, which provides connection of the same number of cores to each switch that form the domain. Domains in the system interact and they represent a regular structure. Alternative solution presents usage of heterogeneous topology; this fact assumes consideration of specific core features during design stage of the designed system. Number of routers and switching method are selected with the purpose of minimization of signal latency, chip size and power consumption. Heterogeneous topology helps to design specialized applications with minimal versatile properties. There is provided mathematical model of the user network-on-chip (NoC). There is provided search shortest path in the flow chart. Obtained outputs of algorithm operation for NoC topology optimization are provided.
Keywords: irregular noc, design automation of noc, network-on-chip (noc)
Visitors: 7951

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