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Wyświetlanie 1-9 z 9
Tytuł:
The Methodology of Analysis on Geometrical Changes of a Mixed Zone in Resistance-Heated Samples
Autorzy:
Dębiński, T.
Głowacki, M.
Hojny, M.
Powiązania:
https://bibliotekanauki.pl/articles/353320.pdf
Data publikacji:
2019
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
mixed zone
resistance heating
computer simulation
visualization
computational geometry
Opis:
The article presents the use of computer graphics methods and computational geometry for the analysis on changes of geometrical parameters for a mixed zone in resistance-heated samples. To perform the physical simulation series of resistance heating process, the Gleeble 3800 physical simulator, located in the Institute for Ferrous Metallurgy in Gliwice, was used. The paper presents a description of the test stand and the method for performing the experiment. The numerical model is based on the Fourier-Kirchoff differential equation for unsteady heat flow with an internal volumetric heat source. In the case of direct heating of the sample, geometrical parameters of the remelting zone change rapidly. The described methodology of using shape descriptors to characterise the studied zone during the process allows to parametrise the heat influence zones. The shape descriptors were used for the chosen for characteristic timing steps of the simulation, which allowed the authors to describe the changes of the studied parameters as a function of temperature. Additionally, to determine the impact of external factors, the remelting zone parameters were estimated for two types of grips holding the sample, so-called hot grips of a shorter contact area with the sample, and so-called cold grips. Based on the collected data, conclusions were drawn on the impact of the process parameters on the localisation and shape of the mushy zone.
Źródło:
Archives of Metallurgy and Materials; 2019, 64, 4; 1463-1470
1733-3490
Pojawia się w:
Archives of Metallurgy and Materials
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Generation of cryptographic keys with algorithm of polygon triangulation and catalan numbers
Autorzy:
Saracevic, M.
Selimi, A.
Selimovic, F.
Powiązania:
https://bibliotekanauki.pl/articles/305390.pdf
Data publikacji:
2018
Wydawca:
Akademia Górniczo-Hutnicza im. Stanisława Staszica w Krakowie. Wydawnictwo AGH
Tematy:
computational geometry
polygon triangulation
Catalan numbers
cryptography
hidden cryptographic keys
Opis:
In this paper, a procedure for the application of one computational geometry algorithm in the process of generating hidden cryptographic keys from one segment of a 3D image is presented. The presented procedure consists of three phases. In the first phase, the separation of one segment from the 3D image and determination of the triangulation of the separated polygon are done. In the second phase, a conversion from the obtained triangulation of the polygon in the record that represents the Catalan key is done. In the third phase, the Catalan-key is applied in the encryption of the text based on the balanced parentheses combinatorial problem.
Źródło:
Computer Science; 2018, 19 (3); 243-256
1508-2806
2300-7036
Pojawia się w:
Computer Science
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Generating placated random shapes for an area estimation study
Autorzy:
Almowanes, A.
Kakiashvili, T.
Koczkodaj, W. W.
Powiązania:
https://bibliotekanauki.pl/articles/123002.pdf
Data publikacji:
2013
Wydawca:
Politechnika Częstochowska. Wydawnictwo Politechniki Częstochowskiej
Tematy:
image processing
Gaussian blur
random polygon
computational geometry
cognitive process
software testing
przetwarzanie obrazów
geometria obliczeniowa
proces poznawczy
testowanie oprogramowania
Opis:
Random but visually nice shapes are often needed for cognitive experiments and processes. This study describes a heuristic for generating random but nice shapes. We call them placated shapes. These shapes are produced by applying the Gaussian blur to randomly generated polygons. Subsequently, the threshold is set to transform pixels to black and white from different shades of gray. This transformation produces placated shapes for easier estimation of areas. Randomly generated placated shapes are used for testing the accuracy of cognitive processes by pairwise comparisons. They can also be used in many other areas such as computer games or software testing. Such shapes could also be used for camouflaging heavy army equipment.
Źródło:
Journal of Applied Mathematics and Computational Mechanics; 2013, 12, 2; 5-13
2299-9965
Pojawia się w:
Journal of Applied Mathematics and Computational Mechanics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Implementation and evaluation of medical imaging techniques based on conformal geometric algebra
Autorzy:
Franchini, Silvia
Gentile, Antonio
Vassallo, Giorgio
Vitabile, Salvatore
Powiązania:
https://bibliotekanauki.pl/articles/329970.pdf
Data publikacji:
2020
Wydawca:
Uniwersytet Zielonogórski. Oficyna Wydawnicza
Tematy:
medical image segmentation
medical image registration
computational geometry
Clifford algebra
conformal geometric algebra
segmentacja obrazu
rejestracja obrazu medycznego
geometria obliczeniowa
algebra Clifforda
Opis:
Medical imaging tasks, such as segmentation, 3D modeling, and registration of medical images, involve complex geometric problems, usually solved by standard linear algebra and matrix calculations. In the last few decades, conformal geometric algebra (CGA) has emerged as a new approach to geometric computing that offers a simple and efficient representation of geometric objects and transformations. However, the practical use of CGA-based methods for big data image processing in medical imaging requires fast and efficient implementations of CGA operations to meet both real-time processing constraints and accuracy requirements. The purpose of this study is to present a novel implementation of CGA-based medical imaging techniques that makes them effective and practically usable. The paper exploits a new simplified formulation of CGA operators that allows significantly reduced execution times while maintaining the needed result precision. We have exploited this novel CGA formulation to re-design a suite of medical imaging automatic methods, including image segmentation, 3D reconstruction and registration. Experimental tests show that the re-formulated CGA-based methods lead to both higher precision results and reduced computation times, which makes them suitable for big data image processing applications. The segmentation algorithm provides the Dice index, sensitivity and specificity values of 98.14%, 98.05% and 97.73%, respectively, while the order of magnitude of the errors measured for the registration methods is 10-5.
Źródło:
International Journal of Applied Mathematics and Computer Science; 2020, 30, 3; 415-433
1641-876X
2083-8492
Pojawia się w:
International Journal of Applied Mathematics and Computer Science
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Numerical simulation of the laser welding
Symulacja procesu laserowego spawania
Autorzy:
Siwek, A.
Powiązania:
https://bibliotekanauki.pl/articles/305496.pdf
Data publikacji:
2008
Wydawca:
Akademia Górniczo-Hutnicza im. Stanisława Staszica w Krakowie. Wydawnictwo AGH
Tematy:
obróbka laserowa
komputerowa dynamika płynów
efekt Marangoniego
przemiany fazowe
kształt strefy przetopionej
laser treatment
computational fluid dynamics (CFD)
Marangoni effect
metallurgical transformation
geometry of the melted zone
Opis:
The model takes into consideration thermophysical and metallurgical properties of th remelting steel, laser beam parameters and boundary conditions of the process. As a result of heating the material, in the area of laser beam operation a weld pool is being created whose shape and size depends on convection caused by the Marangoni force. The direction of the liquid stream depends on the temperature gradient on the surface and on the chemical composition as well. The model created allows to predict the weld pool shape depending on material properties, beam parameters, and boundary conditions of the sample.
Model uwzględnia własności termofizyczne i metalurgiczne przetapianej stali, parametry wiązki laserowej i warunki brzegowe procesu. W wyniku nagrzania materiału w obszarze działania wiązki lasera tworzy się jeziorko cieczy, którego kształt i rozmiar zależą od konwekcji wywołanej siłą Marangoniego. Kierunek strumienia cieczy zależy od gradientu temperatury na powierzchni, a także składu chemicznego. Utworzony model pozwala na przewidywanie kształtu strefy przetopionej w zależności od własności fizycznych materiału, parametrów wiązki i warunków brzegowych próbki.
Źródło:
Computer Science; 2008, 9; 137-146
1508-2806
2300-7036
Pojawia się w:
Computer Science
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Numerical analysis of influence of ship hull form modification on ship resistance and propulsion characteristics. Part I. Influence of hull form modification on ship resistance characteristics
Autorzy:
Szelangiewicz, T.
Abramowski, T.
Powiązania:
https://bibliotekanauki.pl/articles/258900.pdf
Data publikacji:
2009
Wydawca:
Politechnika Gdańska. Wydział Inżynierii Mechanicznej i Okrętownictwa
Tematy:
ship hull geometry
computational fluid dynamics (CFD)
resistance
wake
propeller efficiency
Opis:
After signing ship building contract shipyard’s design office orders performance of ship resistance and propulsion model tests aimed at, apart from resistance measurements, also determination of ship speed, propeller rotational speed and propulsion engine power for the designed ship, as well as improvement of its hull form, if necessary. Range of ship hull modifications is practically very limited due to cost and time reasons. Hence numerical methods, mainly CFD ones are more and more often used for such tests. In this paper consisted of 3 parts, are presented results of numerical calculations of hull resistance, wake and efficiency of propeller operating in non-homogenous velocity field, performed for research on 18 hull versions of B573 ship designed and built by Szczecin Nowa Shipyard.
Źródło:
Polish Maritime Research; 2009, 4; 3-8
1233-2585
Pojawia się w:
Polish Maritime Research
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Numerical analysis of influence of ship hull form modification on ship resistance and propulsion characteristics. Part II. Influence of hull form modification on wake current behind the ship
Autorzy:
Abramowski, T.
Szelangiewicz, T.
Powiązania:
https://bibliotekanauki.pl/articles/259395.pdf
Data publikacji:
2010
Wydawca:
Politechnika Gdańska. Wydział Inżynierii Mechanicznej i Okrętownictwa
Tematy:
ship hull geometry
numerical (computational) fluid dynamics
resistance
wake
propeller efficiency
Opis:
After signing ship building contract shipyard’s design office orders performance of ship resistance and propulsion model tests aimed at, apart from resistance measurements, also determination of ship speed, propeller rotational speed and propulsion engine power for the designed ship, as well as improvement of its hull form, if necessary. Range of ship hull modifications is practically very limited due to cost and time reasons. Hence numerical methods, mainly CFD ones are more and more often used for such tests. In this paper consisted of three parts, are presented results of numerical calculations of hull resistance, wake and efficiency of propeller operating in non-homogenous velocity field, performed for research on 18 hull versions of B573 ship designed and built by Szczecin Nowa Shipyard.
Źródło:
Polish Maritime Research; 2010, 1; 3-9
1233-2585
Pojawia się w:
Polish Maritime Research
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The theoretical investigation on influence the fuel spray geometry on the combustion and emission characteristic of the marine diesel engine
Autorzy:
Kowalski, J.
Powiązania:
https://bibliotekanauki.pl/articles/133037.pdf
Data publikacji:
2017
Wydawca:
Polskie Towarzystwo Naukowe Silników Spalinowych
Tematy:
marine engine
Computational Fluid Dynamics
CFD
combustion model
fuel injection
emission
silnik okrętowy
obliczeniowa mechanika płynów
model spalania
wtryskiwacz paliwa
emisja
Opis:
The paper presents an analysis of the influence of the fuel spray geometry on the combustion and emission characteristic of the marine 4-stroke Diesel engine. Presented analysis was prepared based on computational fluid dynamic model (CFD). Initial and boundary conditions of the model as well as data used to model validation were collected during the laboratory study. Calculations were conducted for two different fuel injectors with changed nozzle holes diameters, the number of nozzle holes and the angle between holes axis. The increase of the fuel nozzle holes diameter causes the decrease of the fuel spray tip penetration, but simultaneously the decrease of holes number causes that auto-ignition delay is not changed. The increase of the angle between holes axis from 150° to 158° causes fuel ingintion near cylinder head wall. Result of this is the increase of CO fraction. The deterioration of fuel combustion causes the decrease of NOx mass fraction in the cylinder also.
Źródło:
Combustion Engines; 2017, 56, 2; 101-107
2300-9896
2658-1442
Pojawia się w:
Combustion Engines
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Numerical analysis of influence of ship hull form modification on ship resistance and propulsion characteristics. Part III. Influence of hull form modification on screw propeller efficiency
Autorzy:
Abramowski, T.
Żelazny, K.
Szelangiewicz, T.
Powiązania:
https://bibliotekanauki.pl/articles/259371.pdf
Data publikacji:
2010
Wydawca:
Politechnika Gdańska. Wydział Inżynierii Mechanicznej i Okrętownictwa
Tematy:
ship hull geometry
numerical (computational) fluid dynamics (CFD)
resistance
wake current
propeller efficiency
Opis:
After signing ship building contract shipyard’s design office orders performance of ship resistance and propulsion model tests aimed at, apart from resistance measurements, also determination of ship speed, propeller rotational speed and propulsion engine power for the designed ship, as well as improvement of its hull form, if necessary. Range of ship hull modifications is practically very limited due to cost and time reasons. Hence numerical methods, mainly CFD ones are more and more often used for such tests. In this paper consisted of three parts, are presented results of numerical calculations of hull resistance, wake and efficiency of propeller operating in non-homogenous velocity field, performed for research on 18 hull versions of B573 ship designed and built by Szczecin Nowa Shipyard.
Źródło:
Polish Maritime Research; 2010, 1; 10-13
1233-2585
Pojawia się w:
Polish Maritime Research
Dostawca treści:
Biblioteka Nauki
Artykuł
    Wyświetlanie 1-9 z 9

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