TASK Quarterly   Scientific Bulletin of the Centre of Informatics - Tricity Academic Supercomputer & networK   ISSN 1428-6394

Volume 23, Number 1, 2019


Contents:



Abstracts:

  • Aleksander Dawid GPU-Based Parallel Algorithm of Interaction Induced Light Scattering Simulations in Fluids

    We parallelized the sequential algorithm of the four-body correlation function if each combination of two pairs (𝑖,𝑗) and (𝑘,𝑙) was averaged over the time in a separate calculation thread. The generator of pairs used as the input for this algorithm was also parallelized and connected with the 4-body correlation function calculations. We used our algorithm to accelerate extremely intensive calculations of the 4-body polarizability anisotropy correlation functions, which were very important to estimate the interaction induced light scattering spectrum. The resulting C code was used to test our algorithm on Graphics Processing Units (GPUs) with the Compute Unified Device Architecture (CUDA) technology from NVIDIA® Corporation. As a result, we achieved 12 times the acceleration of the 4-body correlation function calculations in comparison to the Central Processing Unit (CPU) core. The peak performance of the GPU calculations was registered at the level of 19 times faster than the CPU core. We also found that acceleration depended on the memory consumption. In the single precision mode, the relative error between the CPU and GPU calculations was found to be within 0.1%.

  • Artur Anus and Paweł Buchwald Safe Locker – a Secure Cargo Transport Control Support IT System

    The article presents the assumptions and architectural implementation of a cargo transport control support system, as well as the preliminary results of tests of the operation of this system in environmental conditions identical with the conditions of natural operation. The aim of the article is the publication of the research results collected during the design, implementation and operation of the system, which relate to the proposed solutions for selected problems that emerged during the development of the system by the research and development team. The article also presents the completed development work and possibilities in the field of the system improvement due to security reasons through integration with modern data processing systems based on a block chain (Blockchain).

  • Wiesław Maleszewski The Arithmetic of the Topologist's Sine Curve in Cryptographic Systems Dedicated to IoT Devices

    When observing the modern world, we can see the dynamic development of new technologies, among which a special place, both owing to the potential and the threats is occupied by the Internet of Things which penetrates almost all areas of our life. It is assumed that the IoT technology makes our life easier, however, it poses many challenges concerning the protection of the security of information transmission and, therefore, our privacy. One of the main goals of the paper is to present a new unconventional arithmetic based on the transcendental curve dedicated to the cryptographic systems that protect the transmission of short messages. The use of this arithmetic may develop the possibilities of protecting short sequences of data generated by devices with limited computational power. Examples of such devices include the ubiquitously used battery powered sensors, the task of which is to collect and transmit data which very often comprises concise information. Another goal is to present the possibility of using the developed arithmetic in cryptographic algorithms.

  • Yevhen Chaplya, Olha Chernukha and Yurii Bilushchak Matrix Green's Function of Double-Diffusivity Problem and its Applications to Problems with Inner Point Source

    The matrix Green's function of the initial-boundary value problem of admixture double-diffusivity is defined. The initial-boundary value problem with a point source is formulated for the matrix elements for determination of the matrix Green's function. Formulae for matrix elements are obtained and the behavior of Green's functions is investigated. It is shown that the surface generated by the Green's function has a typical sharp peak in the vicinity of the point of action of the point mass source, and in the vicinity of the top boundary of the layer, the values of the second element of the Green's function are times higher than the values of the first one the state of which is corresponding to the quick migration way. On this basis the solutions of the initial-boundary value problems under the action of the internal point source of mass are found. The cases of the deterministic source as well as stochastic ones under uniform and triangular distributions of the coordinate of the mass source location are considered.

  • Anna Perelomova Magnetoacoustic Heating and Streaming in a Plasma with Finite Electrical Conductivity

    Nonlinear effects of planar and quasi-planar magnetosound perturbations are discussed. Plasma is assumed to be an ideal gas with a finite electrical conductivity permeated by a magnetic field orthogonal to the trajectories of gas particles. The excitation of non-wave modes in the field of intense magnetoacoustic perturbations, i.e., magnetoacoustic heating and streaming, is discussed. The analysis includes a derivation of instantaneous dynamic equations independent of the spectrum and periodicity of sound.

  • Artur Szymański and Sławomir Dykas Evaluation of Leakage through Labyrinth Seals with Analytical Models

    Secondary flows in turbomachinery highly affect the overall efficiency and rotor stability. A prime example of such a phenomenon are leakage flows. Despite their complexity, they can often be estimated with simple semi-empirical formulae, solved with hand calculations. Such an approach is much more cost and time effective during the design process. The formulae consists of a carry-over coefficient and a discharge coefficient elements. To evaluate the leakage properly, an adequate model of the carry-over coefficient has to be developed. This paper presents how the flow conditions and the cavity geometry changes in a straight through labyrinth seal affect the amount of leakage. The effect of the number of teeth, the gap size, the Reynolds number and the pressure ratio are considered. The data to validate the results was obtained from an in-house experiment, where a vast number of cases was tested. Additionally, the study was supported by a two-dimensional steady-state CFD study. Eleven analytical models, Including both very simple as well as more sophisticated methods, were solved according to the experimental case and compared. Six different seal configurations were examined. They included straight through seals with two and three straight knives for various gap sizes. The comparison highlighted differences in the results for models – a certain group presented underestimated results. However, another group of models – presented an excellent agreement with the experimental data. Based on this study, a group of models representing the results within the 10% uncertainty band was selected.

  • Leonardo Pasini and Lorenzo Bianchini Simulation of a Vehicular Traffic System Based on Queuing Network Models

    This work is part of the research activities developed in our department on the construction of vehicle traffic system simulators (TASK Quart. 22 (2) 135 [1], 20 (1) 9 [2], 17 (3) 155 [3], 20 (3) 273 [5], 14 (4) 405 [6], 9 (4) 397 [7], Simulation Modelling Practice and Theory 17 (4) 625 [8]). The modeling of the traffic system is implemented through the use of queuing networks. In this case we analyze, through a simulation, the impact on traffic flows of a structural change that the Municipal Administration has implemented on the urban road system. The study refers to some works published by us previously about the procedures applied by us to build a simulator. In this case we have developed software allowing us to analyze the data tracked by the system simulations to display it graphically. This procedure enables us to clearly compare the traffic system behavior in its new configuration with the traffic system behavior in the previous configuration.