The Energy Efficiency Evaluating Method Determining Energy Consumption of the Parallel Program According to its Profile

The paper is devoted to the evaluation of energy efficiency of High Performance  Computing systems used in a scientific supercomputer center. The authors propose a method for the comparison of energy efficiency of computing systems based on the power consumption and execution time of parallel programs. The paper presents a software tool that allows to determine the energy consumption profile of a parallel program automatically without changing its source code. The paper also presents the results of power consumption comparison of NAS Parallel Benchmarks (BT, EP, IS, and LU) tests on computing systems with codenames Intel microprocessors Broadwell, Cascade Lake, Knights Landing and Skylake)

Computer exploration of the ice samples strength using different numerical methods

The exploration of the Arctic region is a very challenging and important problem today. One of the problems, connected with the Arctics’ investigation, is the ice strength change and measurement during the whole year. In this paper we present the results of the ice strength study using different numerical methods on the unstructured and structured grids. We carry out the computations of the ice strength using the discontinuous Galerkin method on unstructured grids and the Prandtl-Reys model. For this, we compute the model, imitating the interaction between an ice field and a vertical bearing. In addition, we calculate the ice strength after the uniaxial compression and bending using the discontinuous Galerkin method. Then, we present the result strength distribution in the ice sample, computed with the help of the grid-characteristic method on the structured grids. The results demonstrate the possibility of the application of the grid-characteristic method on structured grids to the problem of the ice strength study

A family of singular differential equations

A family of singular differential equations with variable coefficients and parameter $k\in \mathbb{R}$ is introduced into the consideration. The properties inherent in all differential equations of this family are investigated and theorems on the solvability of a number of initial problems for the considered family are formulated

Application of hypergeometric functions of several variables in the mathematical theory of communication. II. Evaluation of error probability in fading multichannel system

A method is proposed of evaluation of symbol and/or bit error probabilities for coherent receiving of multipositional signal constructions in communication channel with fadings, which are described with the help of classical and generalized models Multiple-Wave with Diffuse Power (MWDP) fading and of additive white Gaussian noise (AWGN). This method uses the hypergeometric functions of several variables

On the correctness of finite--rank approximations by series of shifted Gaussians

In this paper we consider interpolation problem connected with series by integer shifts of Gaussians.Known approaches for these problems met numerical difficulties. Due to it another method is considered based on finite--rank  approximations by linear systems. The main result for this approach is to establish correctness of the finite--rank linear system under consideration. And the main result of the paper is to prove correctness of the finite--rank linear system approximation. For that an explicit formula for the main determinant of the linear system is derived to demonstrate that it is non--zero

Numerical Study of the Dynamics of a Gas Bubble Near a Wall Under Ultrasound Excitation

A numerical study of the dynamics of a gas bubble in water near a plane rigid wallunder ultrasound excitation has been performed. The bubble dynamics is excited at the naturalfrequency of the radial oscillations of the bubble in the absence of the wall. The dynamics ofthe bubble with the formation on its surface of a cumulative liquid jet directed to the wallis considered. A regime of the ultrasound excitation is investigated, at which the cumulativejet impact against the bubble surface part closer to the wall is realized at the moment of thebeginning of the second expansion of the bubble. At this moment two known mechanisms ofemitting pressure pulses into liquid by a bubble start working simultaneously. The rst one isdue to the bubble expansion. The second one results from the impact of the cumulative jet. Theboundary element method is used. The study has revealed the dependences of the ultrasoundexcitation amplitude, at which the indicated regime is realized, on the distance between thebubble and the wall, as well as the inuence of the bubble-to-wall distance on the jet impactvelocity and the pressure inside the bubble corresponding to that regime

Developing Efficient Implementations of Connected Component Algorithms for NEC SX-Aurora TSUBASA

Modern vector architectures are tend to be equipped with high-bandwidth memory, what makes them an interesting candidate for solving large-scale graph processing problems. However, highly irregular structure of real-world graphs makes it extremely challenging to map fundamental graph-processing problems on vector systems. This paper describes the world- first attempt, aimed to create efficient vector- friendly implementations of various connected components algorithms for modern NEC SX-Aurora TSUBASA architecture, which provides high performance computational power together with a world-highest bandwidth memory. In order to develop fast implementations, supercomputer co-design principles are used, including: the selection of vector-friendly graph algorithms, adapting these algorithms for target archi- tecture, selecting vectorized graph storage format and applying various optimisations aimed to improve the efficiency of using memory hierarchy of target platform. In addition, current paper analyses if similar implementation approaches can be used for modern NVIDIA GPU architectures, which have many common properties and features with SX-Aurora TSUBASA. Finally, a comprehensive comparative performance analysis is presented for all algorithms, architectures and optimisations, discussed in the paper

Generalized discrimination between symmetric coherent states for eavesdropping in quantum cryptography

Symmetric coherent states are of interest in quantum cryptography, since for such states there is an upper bound for unambiguous state discrimination (USD) probability, which is used to resist USD attack. But it is not completely clear what an eavesdropper can do for shorter channel length, when USD attack in not available. We consider the task of generalized discrimination between symmetric coherent states and construct an operation which enlarges the information content of the states with fixed failure probability. We apply this transformation to develop a zero-error eavesdropping strategy for quantum cryptography on symmetric coherent states

Checkpointing tools in a supercomputer center

The article describes the problem of automatic checkpoints creation/data restoration  for the jobs that run on a single supercomputer node. The paper formulates the requirements for the checkpointing and restore tools in the supercomputer job management system. Berkeley Lab Checkpoint/Restart (BLCR), Checkpoint Restore In Userspace (CRIU), and Distributed MultiThreaded Checkpointing (DMTCP) tools are examined. It is shown that the DMTCP tool better meets the stated requirements. Experimental estimates of computational performance and impact on efficiency for DMTCP are presented. The problems of checkpointing tools' integration into the SUPPZ job management system used at the JSCC RAS are considered. Recommendations on the practical use of automatic checkpoint/restore tools are given

Dynamics of gas bubbles inside a ball-like area at the nodes of a uniform cubic mesh under sudden liquid pressure rise

The influence of hydrodynamic interaction between spherical gas bubbles inside a ball-like area at the nodes of a uniform cubic mesh on their dynamics under sudden liquid pressure rise has been investigated. Main attention is payed to the dynamics of a bubble located in the center of such a cluster of cubic structure. Prior to the pressure rise, the liquid and the bubbles are at rest, the liquid pressure is 1 bar, the radii of the bubbles are 0.25 mm, the size of the cubic mesh cells is 5 mm. The increase in the liquid pressure is 3 bar. For the sake of comparison, ball-like clusters with spherical and stochastic structures are also considered, with similar position of the central bubble and with initial minimum distance between the centers of bubbles not exceeding 5 mm. In the clusters of spherical structure, the non-central bubbles are located on concentric spheres with radii of 5 and 10 mm at the nodes of equally-oriented regular polyhedra (icosahedra and dodecahedra). In the clusters of stochastic structure, the non-central bubbles are distributed stochastically in a sphere with radius of 10 mm. A mathematical model is applied, in which the dynamics of bubbles is governed by the ordinary differential equations in the radii of bubbles and the position-vectors of their centers. It is shown that in the case of a cluster with cubic structure, the interaction between the bubbles leads to strengthening the collapse rate of the central bubble and to non-monotonic decay of oscillations of their pressure. Similar features are characteristic of the clusters with spherical and stochastic structures