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    Wyświetlanie 1-10 z 10
    Tytuł:
    Mean field and full field modelling of microstructure evolution and phase transformations during hot forming and cooling of low carbon steels
    Autorzy:
    Szeliga, Danuta
    Bzowski, Krzysztof
    Rauch, Łukasz
    Kuziak, Roman
    Pietrzyk, Maciej
    Powiązania:
    https://bibliotekanauki.pl/articles/29520270.pdf
    Data publikacji:
    2020
    Wydawca:
    Akademia Górniczo-Hutnicza im. Stanisława Staszica w Krakowie. Wydawnictwo AGH
    Tematy:
    mean field models
    full field models
    finite element method
    level set method
    Opis:
    The paper describes a critical comparison of mean field and full field approaches to modelling hot deformation/controlled cooling sequences for steels. Classification of the models, based on the balance between predictive capabilities and computing costs, is presented. Mean field models, which describe microstructure evolution and phase transformations were connected with thermomechanical finite element program and applied to simulation of the hot strip rolling process and cooling of tubes after hot rolling. Full field model described in the paper is a connection of the finite element (FE) and level set (LSM) methods. These methods were used to simulate heating/cooling sequence in the continuous annealing line. A suggestion to use a stochastic model as a bridge between mean field and full field approaches is made.
    Źródło:
    Computer Methods in Materials Science; 2020, 20, 3; 121-132
    2720-4081
    2720-3948
    Pojawia się w:
    Computer Methods in Materials Science
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Vehicle-deck fires aboard RoPax ships: a comparison between numerical modelling and experimental results
    Autorzy:
    Salem, Ahmed
    Powiązania:
    https://bibliotekanauki.pl/articles/259491.pdf
    Data publikacji:
    2019
    Wydawca:
    Politechnika Gdańska. Wydział Inżynierii Mechanicznej i Okrętownictwa
    Tematy:
    vehicle-deck fires
    RoPax ships
    zone models
    field models
    model-scale fire tests
    Opis:
    According to an official study conducted by the IMO Correspondence Group on Casualty Analysis concerning the fire incidents that occurred on the vehicle-decks of RoPax ships, covering the period from 1994 to 2011, it has been shown that a very serious incident has occurred every other year since 2002, resulting in six constructive total losses. The results of this review shed the light on the need to investigate the application of fire models to simulate fire scenarios that may occur on the vehicle-decks aboard RoPax ships. This will be very useful for the RoPax designers who are willing to introduce new technologies or deviate from the current prescriptive regulations of fire safety design in order to reduce the risk of such catastrophic accidents. The aim of this paper is to present the results of a comparison between the predictions of three different fire models and the experimental results of a model-scale fire test that represents a fire scenario on a vehicle-deck aboard a RoPax ship. A statistical analysis technique was used to illustrate the ability of each fire model to predict five outputs of concern. The main conclusion of this comparison is that there is always an optimal fire model that can predict one or more of the five outputs of concern with results in good agreement with the measured values.
    Źródło:
    Polish Maritime Research; 2019, 2; 155-162
    1233-2585
    Pojawia się w:
    Polish Maritime Research
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Temperature distribution in multi domain construction of the permanent magnet linear actuator
    Autorzy:
    Tomczuk, B.
    Waindok, A.
    Powiązania:
    https://bibliotekanauki.pl/articles/140715.pdf
    Data publikacji:
    2013
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    linear actuators
    thermal field models
    heating curves calculation
    finite element model
    Opis:
    The transient thermal model of the permanent magnet linear actuator (PMLA) has been considered. The characteristics of heating have been calculated including the main subdomains of the actuator. The carcasses from various materials have also been considered. The calculations have been verified experimentally and a good conformity was obtained.
    Źródło:
    Archives of Electrical Engineering; 2013, 62, 3; 417-424
    1427-4221
    2300-2506
    Pojawia się w:
    Archives of Electrical Engineering
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Fast model for phase transformations during cooling of pre-annealed multiphase steels
    Szybkie modele przemian fazowych podczas chłodzenia wstępnie wyżarzonych stali wielofazowych
    Autorzy:
    Szeliga, Danuta
    Kuziak, Roman
    Zalecki, Władysław
    Pidvysotskyy, Valeriy
    Chang, Yuling
    Bleck, Wolfgang
    Bachniak, Daniel
    Pietrzyk, Maciej
    Powiązania:
    https://bibliotekanauki.pl/articles/29520329.pdf
    Data publikacji:
    2019
    Wydawca:
    Akademia Górniczo-Hutnicza im. Stanisława Staszica w Krakowie. Wydawnictwo AGH
    Tematy:
    CP steel
    phase transformations
    mean field models
    stal CP
    przemiany fazowe
    średnie modele pola
    Opis:
    A thorough experimental and numerical analysis of phase transformations in a selected CP800 steel was the general objective of the paper. Dilatometric tests were performed for a wide range of cooling rates. Two models based on a mean field approach were considered. The first was an upgrade of the Johnson-Mehl-Avrami-Kolmogorov equation. The second model was based on the Leblond equation. Both models were identified using inverse analysis of the experimental data. Simulations of various cooling schedules were performed to validate the models. Phase compositions for these cooling schedules were determined. Following this the effect of elements' segregation during solidification of steel on the occurrence of marteniste/bainite bands was accounted for using the developed models.
    W artykule opisano doświadczalną i numeryczną analizę przemian fazowych w wybranej stali o podwyższonej wytrzymałości. Próby dylatometryczne wykonano w szerokim zakresie prędkości chłodzenia. Rozważono dwa modele wykorzystujące metodę średniego pola. Pierwszym modelem była zmodernizowana wersja modelu JMAK (Johnson-Mehl-Avrami-Kolmogorov). Drugim modelem było rozwinięcie równania Leblonda. Przeprowadzono identyfikację modeli wykorzystując rozwiązanie odwrotne dla prób dylatometrycznych. W celu walidacji modeli wykonano symulacje różnych schematów chłodzenia. Wyznaczono skład fazowy dla tych schematów. Następnie oszacowano wahania składu chemicznego w badanej stali i wykorzystano opracowane modele do określenie wpływu segregacji pierwiastków podczas krzepnięcia stali na powstawanie pasm martenzytu/bainitu.
    Źródło:
    Computer Methods in Materials Science; 2019, 19, 4; 150-161
    2720-4081
    2720-3948
    Pojawia się w:
    Computer Methods in Materials Science
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Masking of ferromagnetic ellipsoidal shell in Earth’s magnetic field
    Autorzy:
    Jakubiuk, K.
    Wołoszyn, M.
    Zimny, P.
    Powiązania:
    https://bibliotekanauki.pl/articles/97594.pdf
    Data publikacji:
    2013
    Wydawca:
    Politechnika Poznańska. Wydawnictwo Politechniki Poznańskiej
    Tematy:
    mathematical models of magnetic field
    magnetization of ferromagnetic object
    masking of ferromagnetic object
    windings for demagnetization of the ship
    Opis:
    A ferromagnetic object, located in the Earth’s magnetic field, changes the distribution of that field. By measuring such disturbances it is possible to detect the object and destroy it. To conceal the object, a special winding is placed inside its ferromagnetic shell, which function is to eliminate the disturbances in the distribution of the Earth’s magnetic field. A thin walled ellipsoidal shell made of ferromagnetic material are examined as the object model. Coils are placed inside the shell and their function is to generate a magnetic field, which eliminates the effect the shell makes on the distribution of the Earth’s magnetic field in the surrounding area. Such a procedure is called magnetic masking and the winding used for this purpose is called the masking winding. The possibility of building the masking windings for the ferromagnetic ellipsoidal shell, situated in a magnetic field transverse in relation to its major axis, is also examined. Masking of a thin-walled ellipsoidal ferromagnetic object located in the longitudinal magnetic field is described in the article [1]. Investigating the possibility of masking of objects in a transverse magnetic field presented in this article will allow for a comprehensive assessment of a possibility of masking thin walled ferromagnetic objects of elongated ellipsoidal shape. The solution of Maxwell’s equations, which describe the magnetic field distribution caused by the ferromagnetic shell presence in the Earth’s magnetic field, are applied. Furthermore, the ability of selecting coils, which fully eliminate the perturbations of the magnetic field outside the shell are proven.
    Źródło:
    Computer Applications in Electrical Engineering; 2013, 11; 92-99
    1508-4248
    Pojawia się w:
    Computer Applications in Electrical Engineering
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    The Behavioural Model of Graphene Field-effect Transistor
    Autorzy:
    Łuszczek, Maciej
    Turzyński, Marek
    Świsulski, Dariusz
    Powiązania:
    https://bibliotekanauki.pl/articles/1844478.pdf
    Data publikacji:
    2020
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    graphene field effect transistor
    behavioural models
    circuit simulation
    sensors
    Opis:
    The behavioural model of a graphene field-effect transistor (GFET) is proposed. In this approach the GFET element is treated as a “black box” with only external terminals available and without considering the physical phenomena directly. The presented circuit model was constructed to reflect steady-state characteristics taking also into account GFET capacitances. The authors’ model is defined by a relatively small number of equations which are not nested and all the parameters can be easily extracted. It was demonstrated that the proposed model allows to simulate the steady-state characteristics with the accuracy approximately as high as in the case of the physical model. The presented compact GFET model can be used for circuit or system-level simulations in the future.
    Źródło:
    International Journal of Electronics and Telecommunications; 2020, 66, 4; 753-758
    2300-1933
    Pojawia się w:
    International Journal of Electronics and Telecommunications
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Characteristics simulations of the electrodynamic railgun different constructions and their measurement verification
    Autorzy:
    Piekielny, Paweł
    Tomczuk, Bronisław
    Waindok, Andrzej
    Powiązania:
    https://bibliotekanauki.pl/articles/27309948.pdf
    Data publikacji:
    2023
    Wydawca:
    Polska Akademia Nauk. Czasopisma i Monografie PAN
    Tematy:
    3D field analysis
    analysis of transients
    analytical models
    electrodynamic accelerator
    experimental verification
    field-circuit modeling
    projectile velocity
    Opis:
    Dynamic characteristics for three types of railgun constructions were simulated and measured in this work. The simplest construction is the iron-less (IL) railgun, while the two other ones (IC and ICPM) have an iron-core. The iron-core permanent magnet (ICPM) railgun additionally has permanent magnets. To compare their characteristics, similar dimensions of the rails and iron cores were adopted, and the same power supply system was used. Numerical magnetic field analyses and our analytical models have been used to determine the electromagnetic parameters. They were verified experimentally. The transient states of the railguns were studied with our field-circuit mathematical model, and their results were also verified by experiments.
    Źródło:
    Archives of Electrical Engineering; 2023, 72, 4; 951--969
    1427-4221
    2300-2506
    Pojawia się w:
    Archives of Electrical Engineering
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Phase Field Study of Microstructure Evolution in Eutectoid Phase Transformation – I Nucleation
    Autorzy:
    Zhang, D.
    Yin, Y.
    Zhou, J.
    Tu, Z.
    Powiązania:
    https://bibliotekanauki.pl/articles/381800.pdf
    Data publikacji:
    2017
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    eutectoid
    nucleation models
    microstructure
    numerical simulation
    phase field
    eutektoid
    ziarna
    mikrostruktura
    symulacja numeryczna
    Opis:
    Eutectoid growth, as the important reaction mechanism of the carbon steel heat treatment, is the basis to control the microstructure and performance. At present, most studies have focused on lamellar growth, and did not consider the nucleation process. Mainly due to the nucleation theory is inconclusive, a lot of research can support their own theory in a certain range. Based on the existing nucleation theory, this paper proposes a cooperative nucleation model to simulate the nucleation process of eutectoid growth. In order to ensure that the nucleation process is more suitable to the theoretical results, different correction methods were used to amend the model respectively. The results of numerical simulation show that when the model is unmodified, the lateral growth of single phase is faster than that of longitudinal growth, so the morphology is oval. Then, the effects of diffusion correction, mobility correction and ledges nucleation mechanism correction on the morphology of nucleation and the nucleation rate were studied respectively. It was found that the introduction of boundary diffusion and the nucleation mechanism of the ledges could lead to a more realistic pearlite.
    Źródło:
    Archives of Foundry Engineering; 2017, 17, 3; 155-162
    1897-3310
    2299-2944
    Pojawia się w:
    Archives of Foundry Engineering
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    FPGA implementation of logarithmic versions of Baum-Welch and Viterbi algorithms for reduced precision hidden Markov models
    Autorzy:
    Pietras, M.
    Klęsk, P.
    Powiązania:
    https://bibliotekanauki.pl/articles/201874.pdf
    Data publikacji:
    2017
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    hidden Markov models
    numerical stability
    Viterbi algorithm
    parallel architecture
    field-programmable gate array
    ukryte modele Markowa
    stabilność numeryczna
    Algorytm Viterbiego
    architektura równoległa
    Opis:
    This paper presents a programmable system-on-chip implementation to be used for acceleration of computations within hidden Markov models. The high level synthesis (HLS) and “divide-and-conquer” approaches are presented for parallelization of Baum-Welch and Viterbi algorithms. To avoid arithmetic underflows, all computations are performed within the logarithmic space. Additionally, in order to carry out computations efficiently – i.e. directly in an FPGA system or a processor cache – we postulate to reduce the floating-point representations of HMMs. We state and prove a lemma about the length of numerically unsafe sequences for such reduced precision models. Finally, special attention is devoted to the design of a multiple logarithm and exponent approximation unit (MLEAU). Using associative mapping, this unit allows for simultaneous conversions of multiple values and thereby compensates for computational efforts of logarithmic-space operations. Design evaluation reveals absolute stall delay occurring by multiple hardware conversions to logarithms and to exponents, and furthermore the experiments evaluation reveals HMMs computation boundaries related to their probabilities and floating-point representation. The performance differences at each stage of computation are summarized in performance comparison between hardware acceleration using MLEAU and typical software implementation on an ARM or Intel processor.
    Źródło:
    Bulletin of the Polish Academy of Sciences. Technical Sciences; 2017, 65, 6; 935-946
    0239-7528
    Pojawia się w:
    Bulletin of the Polish Academy of Sciences. Technical Sciences
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Evolving morphogenetic fields in the zebra skin pattern based on Turings morphogen hypothesis
    Autorzy:
    Gravan, C. P.
    Lahoz-Beltra, R.
    Powiązania:
    https://bibliotekanauki.pl/articles/907636.pdf
    Data publikacji:
    2004
    Wydawca:
    Uniwersytet Zielonogórski. Oficyna Wydawnicza
    Tematy:
    pole morfogenetyczne
    model reakcji-dyfuzji
    automat komórkowy
    mammalian coat pattern
    morphogenetic field
    Turing reaction-diffusion
    evolving cellular automata
    developmental models
    modeling biological structures
    Opis:
    One of the classical problems of morphogenesis is to explain how patterns of different animals evolved resulting in a consolidated and stable pattern generation after generation. In this paper we simulated the evolution of two hypothetical morphogens, or proteins, that diffuse across a grid modeling the zebra skin pattern in an embryonic state, composed of pigmented and nonpigmented cells. The simulation experiments were carried out applying a genetic algorithm to the Young cellular automaton: a discrete version of the reaction-diffusion equations proposed by Turing in 1952. In the simulation experiments we searched for proper parameter values of two hypothetical proteins playing the role of activator and inhibitor morphogens. Our results show that on molecular and cellular levels recombination is the genetic mechanism that plays the key role in morphogen evolution, obtaining similar results in the presence or absence of mutation. However, spot patterns appear more often than stripe patterns on the simulated skin of zebras. Even when simulation results are consistent with the general picture of pattern modeling and simulation based on the Turing reaction-diffusion, we conclude that the stripe pattern of zebras may be a result of other biological features (i.e., genetic interactions, the Kipling hypothesis) not included in the present model.
    Źródło:
    International Journal of Applied Mathematics and Computer Science; 2004, 14, 3; 351-361
    1641-876X
    2083-8492
    Pojawia się w:
    International Journal of Applied Mathematics and Computer Science
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
      Wyświetlanie 1-10 z 10

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