The general theory of greedy approximation with respect to arbitrary dictionaries is well developed in the case of real Banach spaces. Recently, some of results proved for the Weak Chebyshev Greedy Algorithm (WCGA) in...
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The study of icing processes on elements of an airplane, helicopter, UAV, wind turbines, and power line wires is an urgent task in connection with flight safety and reliable operation of ground equipment. The features...
The study of icing processes on elements of an airplane, helicopter, UAV, wind turbines, and power line wires is an urgent task in connection with flight safety and reliable operation of ground equipment. The features of the numerical simulation of multicomponent reactive mixture flow using the iceFoam solver were considered. The Euler-Lagrangian approach was used to describe the behavior of the two-phase flow with air and liquid droplets. The specifics of the construction of the project on the basis of the computation of the liquid film model for the conditions of the experimental setup for the 2D cylinder and NACA0012 airfoil are discussed. The results of computations of the main parameters of the ice accretion process are given, the efficiency of the iceFoam solver for parallel simulation on two different grids was shown. The computations were run on the high-performance cluster UNIHUB of ISP RAS.
Networks of human interactions (like social and mobile call networks) in most cases inherit natural properties of society, e.g. community structure or tie strength. The method for generating large random mobile call g...
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Networks of human interactions (like social and mobile call networks) in most cases inherit natural properties of society, e.g. community structure or tie strength. The method for generating large random mobile call graphs is introduced. Generated graphs reflect real network properties, such as community structure or Double Pareto Log-Normal degree distribution. Generation time is linear in the number of edges. The proposed method is intended to facilitate evaluation of algorithms designed for mobile call network analysis.
Features of numerical simulation of multicomponent reactive mixture flows using the OpenFOAM package reactingCentralFoam solver are considered. The specifics of the construction of the project on the basis of the calc...
Features of numerical simulation of multicomponent reactive mixture flows using the OpenFOAM package reactingCentralFoam solver are considered. The specifics of the construction of the project on the basis of the calculation of the combustion of the oxygen-hydrogen mixture for the conditions of the experimental setup “Penn State Pre-burner Combustor” are discussed. The results of computations of the main parameters of the combustion process are given, the efficiency of the applied solver is shown.
As a necessary preliminary step toward geophysically significant extrapolations, we study the scale effects in internal wave attractors in the linear and nonlinear regimes. We use two geometrically similar experimenta...
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The wind energy is an important part of renewable energy. The wind farms can operate in various climatic conditions on a large territory of Russian Federation. The features of numerical simulation of turbulent flows u...
The wind energy is an important part of renewable energy. The wind farms can operate in various climatic conditions on a large territory of Russian Federation. The features of numerical simulation of turbulent flows using the OpenFOAM package and SOWFA library are considered. The mathematical model has the equations for mass, momentum and energy conservation for incompressible flow. Large-eddy simulation has been applied in the context of wind turbines operation. Lagrangian-averaged scale-independent dynamic Smagorinsky model is used. Two solvers ABLSolver and pisoFoamTurbine have been used for simulations. The results of computations for two test cases (2 and 12 wind turbines) with definition of the main flow parameters are given, the efficiency of the applied solver is shown.
Various models of solubility of gas in two-phase ows of gas and liquid are considered. Such phenomena play an important role in various technical devices especially at modern nuclear power plants. Mathematical models ...
Various models of solubility of gas in two-phase ows of gas and liquid are considered. Such phenomena play an important role in various technical devices especially at modern nuclear power plants. Mathematical models of bubble ows with gas dissolution, gas phase model, and model of liquid phase dissolution were considered and discussed.
The paper discusses the capabilities of the iceFoam solver for modeling the ice accretion processes for various swept wing profiles and 3D swept wing. The Euler-Lagrangian approach is used to describe the gas-droplet ...
The paper discusses the capabilities of the iceFoam solver for modeling the ice accretion processes for various swept wing profiles and 3D swept wing. The Euler-Lagrangian approach is used to describe the gas-droplet medium. To determine the shape of ice, the model of a liquid film according to the shallow water theory is used. Three different version of solver iceFoam are discussed. The features of the solver algorithm for parallel computations are explained. The numerical cases with swept wing were run for “Rime Ice” and “Glaze Ice”. The distribution of ice thickness and temperature were defined for swept wing with GLC-305 airfoil using iceDyMFoam3. The calculation results are compared with the data of experiments by M. Papadakis. The computations were run on the high-performance cluster UNIHUB of ISP RAS, HPC Kurchatov institute.
Cyber theft is a serious threat to Internet security. It is one of the major security concerns by both network service providers and Internet users. Though sensitive information can be encrypted when stored in non-vol...
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Cyber theft is a serious threat to Internet security. It is one of the major security concerns by both network service providers and Internet users. Though sensitive information can be encrypted when stored in non-volatile memory such as hard disks, for many e-commerce and network applications, sensitive information is often stored as plaintext in main memory. Documented and reported exploits facilitate an adversary stealing sensitive information from an application's memory. These exploits include illegitimate memory scan, information theft oriented buffer overflow, invalid pointer manipulation, integer overflow, password stealing Trojans and so forth. Today's computing system and its hardware cannot address these exploits effectively in a coherent way. This paper presents a unified and lightweight solution, called InfoShield that can strengthen application protection against theft of sensitive information such as passwords, encryption keys, and other private data with a minimal performance impact. Unlike prior whole memory encryption and information flow based efforts, InfoShield protects the usage of information. InfoShield ensures that sensitive data are used only as defined by application semantics, preventing misuse of information. Comparing with prior art, InfoShield handles a broader range of information theft scenarios in a unified framework with less overhead. Evaluation using popular network client-server applications shows that InfoShield is sound for practical use and incurs little performance loss because InfoShield only protects absolute, critical sensitive information. Based on the profiling results, only 0.3% of memory accesses and 0.2% of executed codes are affected by InfoShield.
We consider quantum random walks in an infinite-dimensional phase space constructed using Weyl representation of the coordinate and momentum operators in the space of functions on a Hilbert space which are square inte...
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