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Ivannikov Ispras Open Conference (ISPRAS)

作者： Levin, Mikhail P. Russian Acad Sci Ivannikov Inst Syst Programming Moscow Russia

ISBN: (纸本)9781728112756

A pure second-order scheme of quasi-characteristics based on a pyramidal stencil is applied to the numerical modelling of non-stationary two-phase flows through porous media with the essentially heterogeneous properties. In contrast to well-known other high-resolution schemes with monotone properties, this scheme preserves a second-order approximation in regions, where discontinuities of solutions arise, as well as monotone properties of numerical solutions in those regions despite of well-known Godunov theorem. It is possible because the scheme under consideration is defined on a non-fixed stencil and is a combination of two high-order approximation scheme solutions with different dispersion properties. A special criterion according to which, one or another admissible solution is chosen, plays a key role in this scheme. A simple criterion with local character suitable for parallel computations is proposed. Some numerical results showing the efficiency of present approach in computations of two-phase flows through porous media with strongly discontinuous penetration coefficients are presented.

关键词： Quasi-Characteristics Two-phase Porous Media Flows Heterogeneous Media

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ACCURATE SOLUTION OF THE BOUNDARY INTEGRAL EQUATION IN 2D LAGRANGIAN VORTEX METHOD FOR FLOW SIMULATION AROUND CURVILINEAR AIRFOILS 6

ACCURATE SOLUTION OF THE BOUNDARY INTEGRAL EQUATION IN 2D LA...

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6th International Conference on Particle-Based Methods (PARTICLES) - Fundamentals and Applications

作者： Soldatova, Irina A. Marchevskyl, Ilia K. Kuzmina, Kseniia S. Bauman Moscow State Tech Univ 2 Nd Baumanskaya St5 Moscow 105005 Russia Russian Acad Sci Ivannikov Inst Syst Programming Solzhenitsyn St 25 Moscow 109004 Russia

ISBN: (纸本)9788412110111

The problem of numerical solution of the boundary integral equation is considered for 2D case. Viscous vortex domains (VVD) method is used for flow simulation, so vorticity is generated on the whole surface line of the airfoil, and there are a lot of vortex elements close to the airfoil. The aim of the research is to provide high accuracy of numerical solution of the integral equation;at the same time the computational complexity of the numerical algorithm should be at rather low level. The third-order accuracy numerical scheme, based on piecewise-quadratic solution representation on the curvilinear panels is presented, approximate analytic expressions are obtained for the matrix coefficients. These schemes work perfect in the case of potential flow simulation, when vorticity is absent and also when vortex elements are placed rather far from the airfoil surface line. A trivial way to the accuracy improvement for the closely located vortices, which consists in extremely fine surface line discretization, leads to unacceptably high numerical complexity of the algorithm. This problem is solved by developing semi-analytical correction procedure which makes it possible to achieve high accuracy at extremely coarse surface line discretization. For example, in the model problem of flow simulation around elliptical airfoil with 2:1 semiaxes ratio only 20 panels are required to achieve the error level less than 1 % for arbitrary position of the vortex element in the flow.

关键词： Vortex Method Boundary Integral Equation Curvilinear Panels Galerkin Approach High-Order Scheme Correction Procedure Analytical Solution

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Compositional Environment Modelling for Verification of GNU C Programs

Compositional Environment Modelling for Verification of GNU ...

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Ivannikov Ispras Open Conference (ISPRAS)

作者： Zakharov, Ilja Novikov, Evgeny Russian Acad Sci Ivannikov Inst Syst Programming Moscow Russia

ISBN: (纸本)9781728112756

There is still a gap between rapid development of new verification techniques and their practical application. One of major obstacles to performing sound formal verification of large GNU C programs is the necessity to prepare environment models. Researchers usually propose laborious ad-hoc solutions for environment modelling. Also, few software verification frameworks automate this step but they support a narrow class of software, e.g. device drivers or embedded systems. This paper proposes a method for automated compositional generation of environment models that supports adapting to project specifics and enables scalable software verification of various software. We evaluated the proposed method on device drivers and subsystems of the Linux kernel as well as on BusyBox applets.

关键词： environment model GNU C programs model checking software verification

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Static Analysis of dlsym-like Function Calls

Static Analysis of dlsym-like Function Calls

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Ivannikov Memorial Workshop (IVMEM)

作者： Kudryashov, Evgeny Russian Acad Sci Ivannikov Inst Syst Programming Moscow Russia

ISBN: (纸本)9781538676905

The problem of constructing full call graph of a program can be complicated by absence of indirect calls in the graph. It may happen when a developer decides to invoke a function by pointer. The appearance of functions like dlsym makes it possible. Such functions allows to obtain an address of a function from a library at runtime. The paper suggests two step static analysis for revealing symbols loaded at runtime. The first step collects auxiliary information about a program between translation units, the second applies collected information to analyze individual translation units.

关键词： static analysis call graph jump functions dlsym gcc plugin

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PARALLEL IMPLEMENTATION OF FAST METHODS FOR VORTEX INFLUENCE COMPUTATION IN VORTEX METHODS FOR 2D INCOMPRESSIBLE FLOWS SIMULATION 6

PARALLEL IMPLEMENTATION OF FAST METHODS FOR VORTEX INFLUENCE...

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6th International Conference on Particle-Based Methods (PARTICLES) - Fundamentals and Applications

作者： Leonova, Daria D. Marchevsky, Ilia K. Ryatina, Evgeniya P. Bauman Moscow State Tech Univ 2 Nd Baumanskaya St 5 Moscow 105005 Russia Russian Acad Sci Ivannikov Inst Syst Programming Alexander Solzhenitsyn St 25 Moscow 109004 Russia

ISBN: (纸本)9788412110111

Vortex methods are a powerful tool for solving engineering problems of incompressible flow simulation at small subsonic speeds. The main idea is to consider vorticity as a primary computed variable. Vorticity distribution is simulated by a set of elementary vorticity carriers - vortex elements. Their velocity in the flow is a sum of the convective and diffusive ones. The simplest way to compute the convective velocity of each vortex element is to summarize the influences of all the other vortices, it should be done at every time step. Such problem is similar to the N-body gravitational problem, its computational complexity is proportional to N-2 (N is number of vortices). This fact restricts significantly the applicability of vortex methods. Two approximate fast methods of logarithmic (N log N) computational complexity are implemented and investigated. The first method is analogous of the Barnes Hut fast method for the gravitational N-body problem;the second one is based on the possibility of convolution integral fast calculation through Fast Fourier Transform (FFT) technique with further results correction, which permits to take into account the influence of closely-spaced vortices. Sequential and parallel implementations of both methods are developed. Numerical experiments show that the FFT-based method is more efficient in comparison to the Barnes - Hut method;it provides the acceleration of about 1000 times for the velocities calculation for N = 500 000 vortex elements (in comparison to the direct "point-to-point" calculation). The number of mesh cells doesn't effect the method accuracy, however it determines the computational complexity of the algorithm. It is found that the mesh size should be chosen according to the derived estimation of the algorithm's numerical complexity and available computational resources.

关键词： Vortex Methods Incompressible Media Vortex Influence Calculation Fast Methods Barnes - Hut-type Method Fast Fourier Transform OpenMP MPI

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Study of OpenFOAM® Efficiency for Solving Fluid-Structure Interaction Problems 11th

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11th Workshop on Open Source Field Operation And Manipulation (OpenFOAM)

作者： Kraposhin, Matvey Kuzmina, Ksenia Marchevsky, Ilia Puzikova, Valeria Russian Acad Sci Inst Syst Programming Alexander Solzhenitsyn St 25 Moscow 109004 Russia Bauman Moscow State Tech Univ 2nd Baumanskaya St 5 Moscow 105005 Russia

ISBN: (纸本)9783319608464;9783319608457

In the present research, the well-known test FSI problem of wind resonance phenomenon simulation for a circular cylinder is considered. It is well-investigated, both experimentally and numerically (Chen et al. in Phys Fluids 2011, [3]), for a wide range of parameters: Reynolds number, airfoil surface roughness, incident flow turbulence, etc. In this research, the simplest case is considered, in which the roughness influence is neglected and the incident flow is assumed to be laminar. Several numerical codes, both commercial and open source, can be used for simulating airfoil oscillations in the flow. Four numerical methods and the corresponding open-source codes are considered: the finite volume method with deformable mesh in OpenFOAM (R);the particle finite element method with deformable mesh in the Kratos software;the meshfree Lagrangian vortex element method;and the LS-STAG immersed boundary method. The last two methods are implemented as in-house numerical codes. A comparison is carried out for the efficiency analysis of these methods and their implementations. It is shown that using OpenFOAM (R) is preferable for numerical simulations with FSI problems similar to the ones presented here, in which the investigation of system behavior within a wide range of parameters is required.

关键词： Surface roughness

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Positional Characteristics for Efficient Number Comparison over the Homomorphic Encryption

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programming AND COMPUTER SOFTWARE 2019年第8期45卷 532-543页

作者： Babenko, M. Tchernykh, A. Chervyakov, N. Kuchukov, V Miranda-Lopez, V Rivera-Rodriguez, R. Du, Z. Talbi, E-G North Caucasus Fed Univ Stavropol Russia CICESE Res Ctr Ensenada Baja California Mexico Russian Acad Sci Inst Syst Programming Moscow Russia South Ural State Univ Chelyabinsk Russia Tsinghua Univ Beijing Peoples R China Univ Lille Villeneuve Dascq France

Modern algorithms for symmetric and asymmetric encryptions are not suitable to provide security of data that needs data processing. They cannot perform calculations over encrypted data without first decrypting it when risks are high. Residue Number system (RNS) as a homomorphic encryption allows ensuring the confidentiality of the stored information and performing calculations over encrypted data without preliminary decoding but with unacceptable time and resource consumption. An important operation for encrypted data processing is a number comparison. In RNS, it consists of two steps: the computation of the positional characteristic of the number in RNS representation and comparison of its positional characteristics in the positional number system. In this paper, we propose a new efficient method to compute the positional characteristic based on the approximate method. The approximate method as a tool to compare numbers does not require resource-consuming non-modular operations that are replaced by fast bit right shift operations and taking the least significant bits. We prove that in case when the dynamic range of RNS is an odd number, the size of the operands is reduced by the size of the module. If one of the RNS moduli is a power of two, then the size of the operands is less than the dynamic range. We simulate proposed method in the ISE Design Suite environment on the FPGA Xilinx Spartan-6 SP605 and show that it gains 31% in time and 37% in the area on average with respect to the known approximate method. It makes our method efficient for hardware implementation of cryptographic primitives constructed over a prime finite field.

关键词： Numbering systems

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An Extension of the Method of Aggregated Regulators to a Discrete Stochastic Object

An Extension of the Method of Aggregated Regulators to a Dis...

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International Siberian Conference on Control and Communications (SIBCON)

作者： Kolesnikova, S. Tsvetnitskaya, S. Pobegailo, P. St Petersburg State Univ Aerosp Instrumentat Inst Computat Syst & Programming St Petersburg Russia Natl Res Tomsk State Univ Inst Appl Math & Comp Sci Tomsk Russia RAS AA Blagonravov Mech Engn Res Inst Moscow Russia

ISBN: (纸本)9781538651421

A problem statement for the synthesis of a robust stochastic regulator based on the principles of control on manifolds and a new algorithm for designing a second-order stochastic discrete object are presented. Illustrative examples of solving two applied problems based on the designed regulator are given. The first demonstrates an application of the regulator for controlling an economic object unstable in an open position. The second contains a theoretical result in the form of a new algorithm for synthesizing a system of control over a vector object of the "manipulating system" type, whose physical model represents an implement of a single-bucket hydraulic excavator. The problem of constructing a system of control over the process of stabilization of the bucket angular position is considered. The algorithm for designing a control system and the respective control algorithm applied to the solution of the problem of stabilization of the robot-excavator bucket motion across the engineered surface could be useful for any manipulating systems.

关键词： robust stochastic regulator control on manifolds manipulating systems

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COMPARISON OF THE FINITE VOLUME METHOD WITH LAGRANGIAN VORTEX METHOD FOR 2D FLOW SIMULATION AROUND AIRFOILS AT INTERMEDIATE REYNOLDS NUMBER 6

COMPARISON OF THE FINITE VOLUME METHOD WITH LAGRANGIAN VORTE...

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6th International Conference on Particle-Based Methods (PARTICLES) - Fundamentals and Applications

作者： Kuzmina, Kseniia S. Marchevsky, Ilia K. Ryatina, Evgeniya P. Bauman Moscow State Tech Univ 2 Nd Baumanskaya St 5 Moscow 105005 Russia Russian Acad Sci Ivannikov Inst Syst Programming Alexander Solzhenitsyn St 25 Moscow 109004 Russia

ISBN: (纸本)9788412110111

The paper is dedicated to the numerical simulation of two-dimensional viscous incompressible flow. The Viscous Vortex Domains method is considered, which is one of the modifications of Lagrangian vortex methods. This method is implemented in the open-source VM2D code, which developer by the authors. Model problems of external and internal flow simulation are considered for VM2D testing. For the problem of the flow simulation around two closely spaced circular cylinders, VM2D is compared to OpenFOAM in terms of computational efficiency. As the internal flow problem the flow in a channel with a backward-facing step is considered. For both problems, the results obtained in VM2D are in good agreement with the results of other researchers.

关键词： viscous vortex domain method 2D flow incompressible flow open-source code OpenFOAM VM2D backward-facing step

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Extracting the exact solitons of time-fractional three coupled nonlinear Maccari's system with complex form via four different methods

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RESULTS IN PHYSICS 2022年 36卷 105400-105400页

作者： Chen, Zhuoxun Manafian, Jalil Raheel, Muhammad Zafar, Asim Alsaikhan, Fahad Abotaleb, Mostafa George Sch 1690 Newtown Langhorne Rd Newtown PA 18940 USA Univ Tabriz Fac Math Sci Dept Appl Math Tabriz Iran Lankaran State Univ Nat Sci Fac 50 H Aslanov Str Lankaran Azerbaijan Inst Southern Punjab Dept Math & Stat Multan Pakistan CUI Dept Math Vehari Campus Islamabad Pakistan Prince Sattam Bin Abdulaziz Univ Coll Pharm Dept Clin Pharm Al Kharj Saudi Arabia South Ural State Univ Dept Syst Programming Chelyabinsk 454080 Russia

This current research is considered some new exact soliton solutions to the time-fractional three coupled nonlinear Maccari's system in complex form with novel truncated M-fractional derivative. The obtained results may be used in the description of the model in fruitful way. The novel derivative operator is applied to study the aforementioned model. In addition, the achieved results are included in the form of dark, bright and combo optical solitons. The achieved solutions are also verified by using the MATHEMATICA software. Modified integration methods, namely, the Kudryashov method, the Expa function method, the extended (G & PRIME;/G)-expansion method and the extended ShGEEM are applied to achieve the results. Obtained solutions are remodeled in several hyperbolic and trigonometric forms based on different restrictions between parameters involved in equations and integration constants that appear in the solutions. A few significant ones among the reported solutions are pictured to perceive the physical utility and peculiarity of the considered model using mathematical software. These optical solitons suggest that these three methods are useful, easy to use and effective than other methods.

关键词： Three coupled non-linear Maccari?s system Truncated M-fractional derivative Kudryashov method Exp(a) function method Extended (G'/G)-expansion method Exact solitons Extended shGEEM

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