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Search results for: TURBULENT VORTEX
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Electrical Stimulation Modulates High Gamma Activity and Human Memory Performance
PublicationDirect electrical stimulation of the brain has emerged as a powerful treatment for multiple neurological diseases, and as a potential technique to enhance human cognition. Despite its application in a range of brain disorders, it remains unclear how stimulation of discrete brain areas affects memory performance and the underlying electrophysiological activities. Here, we investigated the effect of direct electrical stimulation...
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Wpływ wybranych parametrów środowiska na przebieg degradacji rur okładzinowych ze stali P110
PublicationMateriały używane na orurowanie odwiertów w poszukiwaniu i wydobyciu ropy i gazu poddawane są niekorzystnym warunkom eksploatacji takich jak: podwyższona temperatura, wysokie ciśnienie, turbulentny przepływ korozyjnych cieczy z zawieszonymi cząstkami stałymi. Jednym z gatunków stali używanych do produkcji rur okładzinowych jest stal P110 (za normą API 5CT) będąca stalą średnio-węglową, niskostopową o wysokiej wytrzymałości. Celem...
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Application of additional factors supporting the microextraction process
PublicationDue to the fact that green analytical chemistry is of high importance, the past two decades have witnessed a rapid growth in the sample preparation area with special emphasis on simplification, miniaturization and automation of extraction procedures. In addition, to accelerate the extraction processes and to improve the separation of analytes, several enhanced parameters are applied. These factors include, ultrasounds, microwaves,...
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The use of liquid crystal thermography TLC and particle image velocimetry PIV in selected technical applications
PublicationNowadays, the energy cost is very high and this problem is carried out to seek techniques for improvement of the aerothermal and thermal (heat flow) systems performances in different technical applications. The transient and steady-state techniques with liquid crystals for the surface temperature and heat transfer coefficient or Nusselt number distribution measurements have been developed. The flow pattern produced by transverse...
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Improvement of Thrust Bearing Calculation Considering the Convectional Heating within the Space between the Pads
PublicationA modern thrust bearing tool is used to estimate the behavior of tilting pad thrust bearings not only in the oil film between pad and rotating collar, but also in the space between the pads. The oil flow in the space significantly influences the oil film inlet temperature and the heating of pad and collar. For that reason, it is necessary to define an oil mixing model for the space between the pads. In the bearing tool, the solutions...
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Minichannel and minigap classification criteria based on the aspect ratio of the minigeometry: A numerical study
PublicationA detailed numerical investigation has been carried out to analyze the diabatic flow distribution and velocity profile in 18 minigeometries with various aspect ratios for V-type and I-type flow configurations (for 36 cases) assuming ethanol as a working fluid. The aim of the study is to distinguish the value of the aspect ratio for which the flow in minigeometry starts to be two-dimensional (minigap). Cases with a constant Reynolds...
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Brushing with additional cleaning restrictions
PublicationIn graph cleaning problems, brushes clean a graph by traversing it subject to certain rules. We consider the process where at each time step, a vertex that has at least as many brushes as incident, contaminated edges, sends brushes down these edges to clean them. Various problems arise, such as determining the minimum number of brushes (called the brush number) that are required to clean the entire graph. Here, we study a new variant...
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Reconfiguring Minimum Dominating Sets in Trees
PublicationWe provide tight bounds on the diameter of γ-graphs, which are reconfiguration graphs of the minimum dominating sets of a graph G. In particular, we prove that for any tree T of order n ≥ 3, the diameter of its γ-graph is at most n/2 in the single vertex replacement adjacency model, whereas in the slide adjacency model, it is at most 2(n − 1)/3. Our proof is constructive, leading to a simple linear-time algorithm for determining...
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Implementation of Coprocessor for Integer Multiple Precision Arithmetic on Zynq Ultrascale+ MPSoC
PublicationRecently, we have opened the source code of coprocessor for multiple-precision arithmetic (MPA). In this contribution, the implementation and benchmarking results for this MPA coprocessor are presented on modern Zynq Ultrascale+ multiprocessor system on chip, which combines field-programmable gate array with quad-core ARM Cortex-A53 64-bit central processing unit (CPU). In our benchmark, a single coprocessor can be up to 4.5 times...
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Strategic balance in graphs
PublicationFor a given graph G, a nonempty subset S contained in V ( G ) is an alliance iff for each vertex v ∈ S there are at least as many vertices from the closed neighbourhood of v in S as in V ( G ) − S. An alliance is global if it is also a dominating set of G. The alliance partition number of G was defined in Hedetniemi et al. (2004) to be the maximum number of sets in a partition of V ( G ) such that each set is an alliance. Similarly,...
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Certified domination
PublicationImagine that we are given a set D of officials and a set W of civils. For each civil x ∈ W, there must be an official v ∈ D that can serve x, and whenever any such v is serving x, there must also be another civil w ∈ W that observes v, that is, w may act as a kind of witness, to avoid any abuse from v. What is the minimum number of officials to guarantee such a service, assuming a given social network? In this paper, we introduce...
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Human verbal memory encoding is hierarchically distributed in a continuous processing stream
PublicationProcessing of memory is supported by coordinated activity in a network of sensory, association, and motor brain regions. It remains a major challenge to determine where memory is encoded for later retrieval. Here we used direct intracranial brain recordings from epilepsy patients performing free recall tasks to determine the temporal pattern and anatomical distribution of verbal memory encoding across the entire human cortex. High...
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Secure Italian domination in graphs
PublicationAn Italian dominating function (IDF) on a graph G is a function f:V(G)→{0,1,2} such that for every vertex v with f(v)=0, the total weight of f assigned to the neighbours of v is at least two, i.e., ∑u∈NG(v)f(u)≥2. For any function f:V(G)→{0,1,2} and any pair of adjacent vertices with f(v)=0 and u with f(u)>0, the function fu→v is defined by fu→v(v)=1, fu→v(u)=f(u)−1 and fu→v(x)=f(x) whenever x∈V(G)∖{u,v}. A secure Italian dominating...
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On trees with equal 2-domination and 2-outer-independent domination numbers
PublicationFor a graph G = (V,E), a subset D \subseteq V(G) is a 2-dominating set if every vertex of V(G)\D$ has at least two neighbors in D, while it is a 2-outer-independent dominating set if additionally the set V(G)\D is independent. The 2-domination (2-outer-independent domination, respectively) number of G, is the minimum cardinality of a 2-dominating (2-outer-independent dominating, respectively) set of G. We characterize all trees...
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A lower bound on the total outer-independent domination number of a tree
PublicationA total outer-independent dominating set of a graph G is a set D of vertices of G such that every vertex of G has a neighbor in D, and the set V(G)D is independent. The total outer-independent domination number of a graph G, denoted by gamma_t^{oi}(G), is the minimum cardinality of a total outer-independent dominating set of G. We prove that for every nontrivial tree T of order n with l leaves we have gamma_t^{oi}(T) >= (2n-2l+2)/3,...
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Magneto-thermal convection of low concentration nanofluids
PublicationThe main aim of this paper was to analyze possible utilization of the low concentration nanofluids and the magnetic field to enhance heat transfer. The studied fluids were based on water with an addition of copper particles (40-60 nm diameter). They belonged to the diamagnetic group of materials. As a first attempt to stated target the analysis of enclosure placed in the maximal value of square magnetic induction gradient was carried...
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Experimental and Computational Fluid Dynamics Studies on Straight and U-Bend Double Tube Heat Exchangers with Active and Passive Enhancement Methods
PublicationIn this work, the authors wanted to demonstrate the possibility to increase the heat transfer efficiency by using simple wire coil inserts to create turbulent flow in the boundary layer as well as air blowing into the annulus of the pipe. Experimental investigations were carried out for four heat exchanger constructions, i.e., plain double tube, turbulized double tube, plain U-bend double tube, U-tube with turbulator, plain double...
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On trees attaining an upper bound on the total domination number
PublicationA total dominating set of a graph G is a set D of vertices of G such that every vertex of G has a neighbor in D. The total domination number of a graph G, denoted by γ_t(G), is the minimum cardinality of a total dominating set of G. Chellali and Haynes [Total and paired-domination numbers of a tree, AKCE International Journal of Graphs and Combinatorics 1 (2004), 69-75] established the following upper bound on the total domination...
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STM32: Aplikacje i ćwiczenia w języku C. - M. Galewski. -
PublicationW książce przedstawiono nowoczesne, 32-bitowe mikrokontrolery z rodzeniem ARM Cortex-M3. Oprócz opisu poszczególnych ich podukładów, zawarto w niej przede wszystkim wiele przykładowych ćwiczeń, których zaawansowanie jest stopniowane, dzięki czemu czytelnicy są łagodnie wprowadzani w omawianie zagadnienia. Przykłady zamieszczone w książce są bardzo różnorodne, bazują m.in. na czujnikach przyspieszenia i ciśnienia MEMS, interfejsie...
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An Alternative Proof of a Lower Bound on the 2-Domination Number of a Tree
PublicationA 2-dominating set of a graph G is a set D of vertices of G such that every vertex not in D has a at least two neighbors in D. The 2-domination number of a graph G, denoted by gamma_2(G), is the minimum cardinality of a 2-dominating set of G. Fink and Jacobson [n-domination in graphs, Graph theory with applications to algorithms and computer science, Wiley, New York, 1985, 283-300] established the following lower bound on the 2-domination...
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An upper bound on the 2-outer-independent domination number of a tree
PublicationA 2-outer-independent dominating set of a graph G is a set D of vertices of G such that every vertex of V(G)D has a at least two neighbors in D, and the set V(G)D is independent. The 2-outer-independent domination number of a graph G, denoted by gamma_2^{oi}(G), is the minimum cardinality of a 2-outer-independent dominating set of G. We prove that for every nontrivial tree T of order n with l leaves we have gamma_2^{oi}(T) <= (n+l)/2,...
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Radix-4 dft butterfly realization with the use of the modified quadratic residue number system
PublicationW pracy zaprezentowano projektowanie i realizację obliczenia motylkowego dft dla podstawy 4 z użyciem zespolonego systemu resztowego (CRNS) i zmodyfikowanego kwadratowego systemu resztowego (MQRNS). System MQRNS oprócz własności dekompozycyjnych pozwala na realizację mnożenia zespolonego przy zastosowaniu trzech mnożeń rzeczywistych. Przedstawiono konwertery wejściowy CRNS/MQRNS i wyjściowy MQRNS/CRNS, mnożenie zespolone w MQRNS,...
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Some variations of perfect graphs
PublicationWe consider (ψk−γk−1)-perfect graphs, i.e., graphs G for which ψk(H) =γk−1(H) for any induced subgraph H of G, where ψk and γk−1 are the k -path vertex cover number and the distance (k−1)-domination number, respectively. We study (ψk−γk−1)-perfect paths, cycles and complete graphs for k≥2. Moreover, we provide a complete characterisation of (ψ2−γ1)-perfect graphs describing the set of its forbidden induced subgraphs and providing...
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Implementacja wybranych struktur sztucznych sieci neuronowych w cyfrowych układach programowalnych.
PublicationW pracy przedstawiono zagadnienia związane z budową i implementacją sztucznych sieci neuronowych w układach programowalnych typu FPGA. Szczegółowo omówiono implementację pojedynczego neuronu z wykorzystaniem dostępnych zasobów sprzętowych układu Virtex FPGA. Poruszono również zagadnienie optymalizacji struktury sieci do konkretnych zastosowań. Zdefiniowano trzy rodzaje realizacji neuronu: równoległą, równoległo-sekwencyjną i sekwencyjną....
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An upper bound on the total outer-independent domination number of a tree
PublicationA total outer-independent dominating set of a graph G=(V(G),E(G)) is a set D of vertices of G such that every vertex of G has a neighbor in D, and the set V(G)D is independent. The total outer-independent domination number of a graph G, denoted by gamma_t^{oi}(G), is the minimum cardinality of a total outer-independent dominating set of G. We prove that for every tree T of order n >= 4, with l leaves and s support vertices we have...
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System sterowania czujnikami z wykorzystaniem sieci bezprzewodowej w standardzie ieee 802.15.4
PublicationBezprzewodowe sieci sensorowe najczęściej wykorzystywane są w systemach pomiarowo-kontrolnych. Przy realizacji systemu wykorzystano mikrokontroler z rdzeniem Cortex-M3 jako kontroler sieci oraz przekaźniki ZigBee pracujące przy częstotliwości 2,4 GHz. System wymagał stworzenia modułów komunikacyjnych łączących kontroler i przekaźnik radiowy za pomocą interfejsu SPI oraz zaimplementowania stosu odpowiadającego potrzebom aplikacji....
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Wind Conditions in Urban Layout – Numerical and Experimental Research
PublicationThis paper presents research which compares the numerical and the experimental results for different cases of airflow around a few urban layouts. The study is concerned mostly with the analysis of parameters, such as pressure and velocity fields, which are essential in the building industry. Numerical simulations have been performed by the commercial software Fluent, with the use of a few different turbulence models, including...
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Surface Dielectric Barrier Discharge Plasma Actuators
PublicationThis paper presents a part of the works conducted in the Plasmaero European project (task 1.1) on surface dielectric barrier discharge actuators applied to airflow control. The study is divided into several parts. In the first part, the goal is to enhance the electric wind produced by a typical single DBD actuator by optimization of the active electrode shape. For instance, the use of a thin wire instead of a plate air-exposed...
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The method of tribotesting of PVD coated elements in oscillation motion at high temperature
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Practical I-Voting on Stellar Blockchain
PublicationIn this paper, we propose a privacy-preserving i-voting system based on the public Stellar Blockchain network. We argue that the proposed system satisfies all requirements stated for a robust i-voting system including transparency, verifiability, and voter anonymity. The practical architecture of the system abstracts a voter from blockchain technology used underneath. To keep user privacy, we propose a privacy-first protocol that...
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Bipartite theory of graphs: outer-independent domination
PublicationLet $G = (V,E)$ be a bipartite graph with partite sets $X$ and $Y$. Two vertices of $X$ are $X$-adjacent if they have a common neighbor in $Y$, and they are $X$-independent otherwise. A subset $D \subseteq X$ is an $X$-outer-independent dominating set of $G$ if every vertex of $X \setminus D$ has an $X$-neighbor in $D$, and all vertices of $X \setminus D$ are pairwise $X$-independent. The $X$-outer-independent domination number...
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On-line P-coloring of graphs
PublicationFor a given induced hereditary property P, a P-coloring of a graph G is an assignment of one color to each vertex such that the subgraphs induced by each of the color classes have property P. We consider the effectiveness of on-line P-coloring algorithms and give the generalizations and extensions of selected results known for on-line proper coloring algorithms. We prove a linear lower bound for the performance guarantee function...
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Corrosion-erosion damage of heat exchanger tubes by desalted crude oil flowing at shell side.
PublicationRurki wymiennika zostały uszkodzone lokalnie przez odsoloną ropę naftową przepływającą pod ciśnieniem 2,6 MPa i w temperaturze 385-395K. Większość powierzchni rurek nie była uszkodzona i była pokryta osadem związków organicznych i nieorganicznych, zabezpieczającym przed uszkodzeniami. Badania wykluczyły możliwość występowania intensywnej korozji elektrochemicznej na powierzchniach rurek pozbawionych osadu. Przyczyną perforacji...
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Total domination in versus paired-domination in regular graphs
PublicationA subset S of vertices of a graph G is a dominating set of G if every vertex not in S has a neighbor in S, while S is a total dominating set of G if every vertex has a neighbor in S. If S is a dominating set with the additional property that the subgraph induced by S contains a perfect matching, then S is a paired-dominating set. The domination number, denoted γ(G), is the minimum cardinality of a dominating set of G, while the...
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Performance analyses of helical coil heat exchangers. The effect of external coil surface modification on heat exchanger effectiveness
PublicationThe shell and coil heat exchangers are commonly used in heating, ventilation, nuclear industry, process plant, heat recovery and air conditioning systems. This type of recuperators benefits from simple construction, the low value of pressure drops and high heat transfer. In helical coil,centrifugal force is acting on the moving fluid due to the curvature of thetube results in the development. It has been long recognized that the...
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IS THE REGIONAL DIVERGENCE A PRICE FOR THE INTERNATIONAL CONVERGENCE? THE CASE OF THE VISEGRAD GROUP
PublicationThe main goal of this article is to verify whether the Visegrad Group countries are achieving social convergence at national level at the expense of internal divergence. For this purpose, the existence of social beta-, sigma- and gamma-convergence at national and regional level was tested. The author of this article decided to tackle the convergence problem since there is a high risk that countries are trying to catch up at...
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A closer look at how the dispersive liquid–liquid microextraction method works. Investigation of the effect of solvent mixture composition on the quality and stability of the cloudy state
PublicationThe dispersive liquid–liquid microextraction (DLLME) is one of the most popular miniaturized extraction procedures. In this paper, the degree of dispersion and dispersion stability were studied with the aim to assess the correlations of these parameters with efficiency for the selected analytical application. The dependence between the degree of dispersion (cloudy state quality) and its stability obtained by various emulsification...
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I protagonisti della grande distribuzione in Europa
PublicationThe chapter outlines the main aspects of the history of some of the most important big European department stores (El Corte Ingles, Auchan, Carrefour, LeClerc, Aldi, Esselunga and the Finiper Group,
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Comparative Analysis of Numerical and Experimental Studies of the Airflow Around the Sample of Urban Development
PublicationIn this paper, on the background of a short overview of the recent advances in the field of Environmental Wind Engineering (EWE), a comparison of wind tunnel experiment and numerical simulation for some cases of airflow around an urban layout have been reported. The purpose of the study is quantitative and qualitative comparison of measurements in the wind tunnel as well as numerical simulation using Ansys Fluent software. The...
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Flow Analysis of a Kaplan Turbine
PublicationThis monograph is a guide to a method of experimental and numerical flow investigations for Kaplan - type turbines. The numerical calculations were compared with the test results of the model Kaplan turbine. The tests were carried out on the model test rig in the Gdańsk University of Technology. The turbine has been thoroughly experimentally investigated, resulting in the identification of optimum setting combination of the stator...
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What Skills for Multi-Partner Open Innovation Projects? Open Innovation Competence Profile in a Cluster Ecosystem Context
PublicationIndustry 4.0 and the turbulent environment have rendered increasing interest in open inno- vation that extends from the bilateral transmission of expertise to multilateral platform collaborations. Open innovation ventures are seen as intricate collaborations that require the commitment of numer- ous partners during the lifetime of the project. In order to examine the specific competence of open innovation teams, we set the research...
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An O ( n log n ) algorithm for finding edge span of cacti
PublicationLet G=(V,E) be a nonempty graph and xi be a function. In the paper we study the computational complexity of the problem of finding vertex colorings c of G such that: (1) |c(u)-c(v)|>=xi(uv) for each edge uv of E; (2) the edge span of c, i.e. max{|c(u)-c(v)|: uv belongs to E}, is minimal. We show that the problem is NP-hard for subcubic outerplanar graphs of a very simple structure (similar to cycles) and polynomially solvable for...
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Edge subdivision and edge multisubdivision versus some domination related parameters in generalized corona graphs
PublicationGiven a graph G= (V, E), the subdivision of an edge e=uv∈E(G) means the substitution of the edge e by a vertex x and the new edges ux and xv. The domination subdivision number of a graph G is the minimum number of edges of G which must be subdivided (where each edge can be subdivided at most once) in order to increase the domination number. Also, the domination multisubdivision number of G is the minimum number of subdivisions...
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The Use of Liquid Crystal Thermography in Selected Technical and Medical Applications—Recent Development
PublicationThermochromic liquid crystals (TLC) and true-colour digital image processing have been successfully used in non-intrusive technical, industrial and biomedical studies and applications. Thin coatings of TLC at surfaces are utilized to obtain detailed temperature distributions and heat transfer rates for steady or transient processes. Liquid crystals also can be used to make the temperature and velocity fields in liquids visible...
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Experimental and comparative study on the two-phase pressure drop of air-water mixture in U-bend and straight pipe annuli
PublicationIn this paper, the experimental and theoretical analysis of pressure drop in singlephase and two phase-flow were presented for straight and U-bend smooth tube annulus and tube annulus with wire coil insert. Experiments for various boundary conditions were performed. In case of U-tube and straight tube with and without turbulator, tests were made for the water-water and air-water systems. The study covered a wide measuring range,...
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Algorithms for testing security in graphs
PublicationIn this paper we propose new algorithmic methods giving with the high probability the correct answer to the decision problem of security in graphs. For a given graph G and a subset S of a vertex set of G we have to decide whether S is secure, i.e. every subset X of S fulfils the condition: |N[X] \cap S| >= |N[X] \ S|, where N[X] is a closed neighbourhood of X in graph G. We constructed a polynomial time property pseudotester based...
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Sprzętowa implementacja koprocesora dla zastosowań kryptograficznych
PublicationW pracy przedstawiono procedurę implementacji elektronicznej skrzynki podawczej z wykorzystaniem zasobów sprzętowych na płytce FPGA (Filed Programmable Gate Array) typu Virtex 4. Przedstawiono ogólna zasadę działania skrzynki podawczej oraz opisano parametry i właściwości poszczególnych modułów funkcjonalnych systemu tj.: modułu TFTP Trivia File Transfer Protocol), serwera WWW, funkcji skrótu oraz asymetrycznego algorytm kryptograficznego....
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From Linear Classifier to Convolutional Neural Network for Hand Pose Recognition
PublicationRecently gathered image datasets and the new capabilities of high-performance computing systems have allowed developing new artificial neural network models and training algorithms. Using the new machine learning models, computer vision tasks can be accomplished based on the raw values of image pixels instead of specific features. The principle of operation of deep neural networks resembles more and more what we believe to be happening...
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Towards an efficient multi-stage Riemann solver for nuclear physics simulations
PublicationRelativistic numerical hydrodynamics is an important tool in high energy nuclear science. However, such simulations are extremely demanding in terms of computing power. This paper focuses on improving the speed of solving the Riemann problem with the MUSTA-FORCE algorithm by employing the CUDA parallel programming model. We also propose a new approach to 3D finite difference algorithms, which employ a GPU that uses surface memory....
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Optimizing the computation of a parallel 3D finite difference algorithm for graphics processing units
PublicationThis paper explores the possibilities of using a graphics processing unit for complex 3D finite difference computation via MUSTA‐FORCE and WENO algorithms. We propose a novel algorithm based on the new properties of CUDA surface memory optimized for 2D spatial locality and compare it with 3D stencil computations carried out via shared memory, which is currently considered to be the best approach. A case study was performed for...