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Wyświetlanie 1-15 z 150
Tytuł:
Searching for critical conditions during lifeboat launching – simulations
Autorzy:
Dymarski, C.
Dymarski, P.
Kniat, A.
Powiązania:
https://bibliotekanauki.pl/articles/260445.pdf
Data publikacji:
2017
Wydawca:
Politechnika Gdańska. Wydział Inżynierii Mechanicznej i Okrętownictwa
Tematy:
lifeboat launching
numerical simulations
kinematics
Opis:
The article describes numerical simulations of the process of lifeboat launching at the ship’s side. The research aimed at finding the values of ship motion parameters which appear to be most dangerous for people in the lowered lifeboat due to the generated accelerations. The simplified model of ship hull motion adopted at this research stage bases on a superposition of harmonic motions with given amplitudes and periods in six degrees of freedom. The range of the amplitude of motion for each degree of freedom corresponds approximately to that of possible motion of the PANAMAX type ship on the Baltic sea. In total, 120 960 cases of ship hull motion were examined.
Źródło:
Polish Maritime Research; 2017, S 1; 53-58
1233-2585
Pojawia się w:
Polish Maritime Research
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Analysis of the inadequacy of determining the spectral characteristics of optical fibre periodic structures by way of numerical modelling
Autorzy:
Stępniak, Piotr
Kisała, Piotr
Powiązania:
https://bibliotekanauki.pl/articles/221086.pdf
Data publikacji:
2020
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
numerical simulations
fibre Bragg grating
numerical modelling
Opis:
As part of the work, the error level of simulations of uniform optical-fibre Bragg gratings was determined using the transition matrix method. The errors were established by comparing the transmission characteristics of the structures obtained by simulation with the corresponding characteristics arrived at experimentally. To compile these objects, elementary properties of the characteristics were specified, also affecting the applications of Bragg gratings, and compared with each other. The level of error in determining each of these features was estimated. Relationships were also found between the size of the physical properties of Bragg gratings and the level of errors obtained. Based on the findings, the correctness of the simulation of structures with the said method was verified, giving satisfying results.
Źródło:
Metrology and Measurement Systems; 2020, 27, 1; 33-50
0860-8229
Pojawia się w:
Metrology and Measurement Systems
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Numerical methods for fast magnetoacoustic waves in solar coronal loops
Autorzy:
Gruszecki, M.
Murawski, K.
Powiązania:
https://bibliotekanauki.pl/articles/1943226.pdf
Data publikacji:
2009
Wydawca:
Politechnika Gdańska
Tematy:
numerical simulations
Godunov methods
magnetohydrodynamics
Opis:
Numerical methods for standing fast magnetoacoustic kink waves in an isothermal solar coronal slab with a field aligned flow are considered. Such waves are triggered impulsively by a velocity pulse that is initially launched in an ambient medium. The spatial and temporal signatures of these waves are determined by solving two-dimensional, ideal magnetohydrodynamic equations numerically. The Ramses code which resolves complex spatial structures by adopting an adaptive mesh refinement technique and shock-capturing capabilities is used. The numerical results show that spatial and temporal wave signatures are reminiscent to the recent observational findings.
Źródło:
TASK Quarterly. Scientific Bulletin of Academic Computer Centre in Gdansk; 2009, 13, 1-2; 75-81
1428-6394
Pojawia się w:
TASK Quarterly. Scientific Bulletin of Academic Computer Centre in Gdansk
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Behaviour of elasto/visco-plastic workpiece material during machining
Autorzy:
Chodor, J.
Kukiełka, L.
Powiązania:
https://bibliotekanauki.pl/articles/99651.pdf
Data publikacji:
2012
Wydawca:
Wrocławska Rada Federacji Stowarzyszeń Naukowo-Technicznych
Tematy:
machining
modeling
numerical simulations
chip
Opis:
Experimental investigations of plastic deformation and uniaxial tension of elasto/visco-plastic (E/V-P) material (41Cr4) were conducted to characterize the flow behavior of the material. Dynamic effects, constitutive damage law and contact with non-linear friction in simulations were described using updated Lagrangian formulation. That model of the process allows defining advanced simulations of tool's penetration in workpiece and chip formation. The yield stress is taken as a function of the strain and the strain rate in order to reflect realistic behavior of unsteady-state process, a material separation criterion based on the failure strain ?f were determined Finite element simulations were carried out using ANSYS code. The influence of the chosen process parameter in numerical simulations on the chip's shapes was presented. Results revealed good agreements between FEM results and experimental ones.
Źródło:
Journal of Machine Engineering; 2012, 12, 4; 99-116
1895-7595
2391-8071
Pojawia się w:
Journal of Machine Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Analiza wpływu procesu uczenia ze stałym krokiem na tempo zmian ewolucyjnych
The analysis of the impact of constant learning on the rate of evolutionary changes
Autorzy:
Gajer, M.
Powiązania:
https://bibliotekanauki.pl/articles/275378.pdf
Data publikacji:
2010
Wydawca:
Sieć Badawcza Łukasiewicz - Przemysłowy Instytut Automatyki i Pomiarów
Tematy:
ewolucja
symulacje numeryczne
evolution
numerical simulations
Opis:
W przypadku systemów sztucznej inteligencji dwoma rozpatrywanymi najczęściej procesami inspirowanymi odkryciami w zakresie nauk przyrodniczych są ewolucja gatunków oraz zdolność do uczenia się poszczególnych osobników. Jest rzeczą interesującą, że oba wymienione procesy mogą w pewnym stopniu oddziaływać na siebie. W szczególności wprowadzenie uczenia osobników może wywierać widoczny wpływ na tempo ewolucji, jednakże związane z tym zjawiska są jeszcze stosunkowo słabo poznane i jak dotychczas brak jest wyjaśniającej je ogólnej teorii. W artykule rozpatrzono przypadek wpływu uczenia ze stałym krokiem (systematyczne przesuwanie osobników o stałą wartość w kierunku globalnego optimum) na tempo ewolucji w przypadku monotonicznej funkcji dopasowania. Przeprowadzone przez autora symulacje numeryczne wykazały, że w takim przypadku wprowadzenie uczenia prowadzi do spowolnienia tempa zmian ewolucyjnych, co może być tłumaczone zmniejszeniem presji selekcyjnej występującej podczas doboru naturalnego w badanej populacji.
In the case of the artificial intelligence systems the two most commonly examined processes, which are inspired by the discoveries in the field of biological sciences, are evolution of the species and learning of individuals. It is a really interesting fact that these two processes can interact with each other to a certain extent. Especially learning of individuals can have a visible impact on the rate of the evolution, but correlated with this phenomena are still weakly understood and there is no general theory, which could explain them sufficiently. In the paper the impact of constant learning (the individuals are systematically moved over a constant value toward the global optimum) on the rate of the evolution is examined in the case of a monotonic fitness function. The numerical simulations, which were conducted by the author, demonstrated that in the case of the constant learning the evolution is decelerated. This fact can be explained by reducing the selection pressure during the natural selection within the examined population.
Źródło:
Pomiary Automatyka Robotyka; 2010, 14, 2; 751-760
1427-9126
Pojawia się w:
Pomiary Automatyka Robotyka
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Numerical Evaluation of the Impact of Riser Geometry on The Shrinkage Defects Formation in the Solidifying Castin
Autorzy:
Sowa, L.
Skrzypczak, T.
Kwiatoń, P.
Powiązania:
https://bibliotekanauki.pl/articles/2048812.pdf
Data publikacji:
2022
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
numerical simulations
solidification
casting defects
FEM
Opis:
The work concerns of modeling the process of manufacturing machine parts by casting method. Making a casting without internal defects is a difficult task and usually requires numerous computer simulations and their experimental verification at the prototyping stage. Numerical simulations are then of priority importance in determining the appropriate parameters of the casting process and in selecting the shape of the riser for the casting fed with it. These actions are aimed at leading shrinkage defects to the riser, so that the casting remains free from this type of defects. Since shrinkage defects usually disqualify the casting from its further use, this type of research is still valid and requires further work. The paper presents the mathematical model and the results of numerical simulations of the casting solidification process obtained by using the Finite Element Method (FEM). A partial differential equation describing the course of thermal phenomena in the process of 3D casting creating was applied. This equation was supplemented with appropriate boundary and initial conditions that define the physical problem under consideration. In numerical simulations, by selecting the appropriate shape riser, an attempt was made to obtain a casting without internal defects, using a simple method of identifying their location. This is the main aim of the research as such defects in the casting disqualify it from use.
Źródło:
Archives of Metallurgy and Materials; 2022, 67, 1; 181-187
1733-3490
Pojawia się w:
Archives of Metallurgy and Materials
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Influence of Liquid Metal Movements on the Casting Creation
Autorzy:
Sowa, Leszek
Skrzypczak, Tomasz
Kwiatoń, Paweł
Powiązania:
https://bibliotekanauki.pl/articles/2049715.pdf
Data publikacji:
2021
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
numerical simulations
solidification
Navier-Stokes equations
Opis:
Knowledge about complex physical phenomena used in the casting process simulation requires continuous complementary research and improvement in mathematical modeling. The basic mathematical model taking into account only thermal phenomena often becomes insufficient to analyze the process of metal solidification, therefore more complex models are formulated, which include coupled heat-flow phenomena, mechanical or shrinkage phenomena. However, such models significantly complicate and lengthen numerical simulations; therefore the work is limited only to the analysis of coupled thermal and flow phenomena. The mathematical description consists then of a system of Navier-Stokes differential equations, flow continuity and energy. The finite element method was used to numerically modeling this problem. In computer simulations, the impact of liquid metal movements on the alloy solidification process in the casting-riser system was assessed, which was the purpose of this work, and the locations of possible shrinkage defects were pointed out, trying to ensure the right supply conditions for the casting to be free from these defects.
Źródło:
Archives of Metallurgy and Materials; 2021, 66, 2; 489-495
1733-3490
Pojawia się w:
Archives of Metallurgy and Materials
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Microstructural effects on damage in composites - computational analysis
Wpływ mikrostruktury na zniszczenie kompozytu - analiza numeryczna
Autorzy:
Mishnaevsky, L. Jr.
Powiązania:
https://bibliotekanauki.pl/articles/281086.pdf
Data publikacji:
2006
Wydawca:
Polskie Towarzystwo Mechaniki Teoretycznej i Stosowanej
Tematy:
damage
composite
finite elements
micromechanics
numerical simulations
Opis:
In this paper, microstructural effects on the damage resistance of composite materials are studied numerically using methods of computational mesomechanics of materials and virtual experiments. Several methods and programs for automatic generation of 3D microstructural models of composites based on the geometrical description of microstructures as well as on the voxel array data have been developed and tested. 3D FE (Finite Element) simulations of the deformation and damage evolution in particle reinforced composites are carried out for different microstructures of the composites. Some recommendations for the improvement of the damage resistance of lightweight metal matrix composites with ceramic reinforcements are obtained.
W artykule przedstawiono analizę wpływu mikrostruktury materiałów kompozytowych na ich odporność na zniszczenie, przeprowadzając badania symulacyjne oparte na modelach obliczeniowych stosowanych w mezo-mechanice oraz na eksperymentach numerycznych. Opisano zaproponowane i przetestowane programy do automatycznego generowania trójwymiarowych modeli mikrostruktur kompozytowych bazujące na opisie geometrycznym z zastosowaniem techniki wokseli (3-wymiarowych odpowiedników pikseli). Przeprowadzono symulacje deformacji i ewolucji zniszczenia elementów skończonych reprezentujących kompozyty z wtrąceniami punktowymi o różnej mikrostrukturze. Sformułowano pewne wytyczne dla poprawy odporności na zniszczenia lekkich kompozytów zbudowanych z metalicznego lepiszcza wzmacnianego ceramiką.
Źródło:
Journal of Theoretical and Applied Mechanics; 2006, 44, 3; 533-552
1429-2955
Pojawia się w:
Journal of Theoretical and Applied Mechanics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Computational studies of gas pipeline junction in unusual operating scenario
Autorzy:
Małachowski, J.
Powiązania:
https://bibliotekanauki.pl/articles/242257.pdf
Data publikacji:
2009
Wydawca:
Instytut Techniczny Wojsk Lotniczych
Tematy:
security
numerical simulations
explosive material
pipeline junction
Opis:
This research has been inspired by security concerns due to the recent increase in the terrorist threat to gas and crude oil transportation around the world, especially in regions that are of significant value for the energy supplies. Computational mechanics methods will be used in this research to apply shock wave analysis for possible damage assessment of the affected pipelines. These methods may be also used for pipelines at power plants, which are usually placed high on the homeland security priority list. The main goal of this research is focused on establishing effective simulation methodology to study the influence of shock waves (caused by explosion) on pipeline infrastructure elements placed on surface to ensure their security. This study is primarily focused on the behaviour of some type of pipeline junction existing in gas pipeline system which can be subjected to the shock wave produced by the detonation ofhighly explosive (HE) materials. Outcomes of this research are important in preventing damage progression of pipelines under the blast loading. This data will also be used to develop improved design guidelines for safer and less vulnerable pipelines.
Źródło:
Journal of KONES; 2009, 16, 2; 299-304
1231-4005
2354-0133
Pojawia się w:
Journal of KONES
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Bipolar growth model with investment flows
Autorzy:
Katarzyna, Filipowicz
Tomasz, Misiak
Tomasz, Tokarski
Powiązania:
https://bibliotekanauki.pl/articles/943113.pdf
Data publikacji:
2016-09-30
Wydawca:
Uniwersytet Ekonomiczny w Poznaniu
Tematy:
Economic growth
investment flows
convergence
numerical simulations
Opis:
The aim of the present study is to design a bipolar model of economic growth with investment flows between two types of economies (conventionally referred to as relatively rich economies and relatively poor economies). Therefore in the following considerations it is assumed that the process of capital accumulation depends on investments undertaken in the economy. At the same time the Solow growth model takes into account only investments financed by domestic savings, whereas in the bipolar growth model also the investment flows between rich and poor economies are considered. It is assumed that both relatively rich economies are investing in the relatively poor economies and the poor economies make investments in the rich economies. The paper analyses the long-term equilibrium of the growth model, both in terms of existence of steady states of the system of differential equations and in terms of the stability of a non-trivial steady state. What is more economic characteristics of the point of the long-term equilibrium of the model are examined, model parameters are calibrated and growth paths of basic macroeconomic variables in selected variants of numerical simulations are presented.
Źródło:
Economics and Business Review; 2016, 2(16), 3; 32-56
2392-1641
Pojawia się w:
Economics and Business Review
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Analysis of flowing fluid effect on flow averaging tube
Autorzy:
Kabaciński, M.
Lachowicz, C.
Pospolita, J.
Powiązania:
https://bibliotekanauki.pl/articles/1943247.pdf
Data publikacji:
2008
Wydawca:
Politechnika Gdańska
Tematy:
flow averaging tubes
numerical simulations
flow measurements
Opis:
This paper presents a mathematical model and results of numerical simulations for a fluid flow around a flow averaging tube. The calculations have been performed using the commercially available FLUENT software. The authors have applied the currently known studies of the models of turbulence and their applicability in certain flow conditions and hence selected the RNG k-epsylon turbulence model including appropriate functions to be used for determination of pressures and velocities at the sites of occurrence of considerable gradients. The distributions of pressures and velocities around a sensor are presented along with pressure distributions, instantaneous and averaged in time, on the measuring tube surface. The paper determines the frequencies of measuring tube free vibrations for one sided and two-sided tube fitting for the tube length in the range 100–1500mm. This analysis has been conducted with the aid of solving equations for free undamped vibrations for specific models. The graphical presentation involves an admissible range of tube lengths with one and two-sided fitting for the specified flowing air velocities.
Źródło:
TASK Quarterly. Scientific Bulletin of Academic Computer Centre in Gdansk; 2008, 12, 3-4; 217-226
1428-6394
Pojawia się w:
TASK Quarterly. Scientific Bulletin of Academic Computer Centre in Gdansk
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Experimental research and numerical analysis of penetration of the twaron T750 aramid fabric with the 9 mm Parabellum projectile
Autorzy:
Wiśniewski, A.
Pacek, D.
Powiązania:
https://bibliotekanauki.pl/articles/403693.pdf
Data publikacji:
2013
Wydawca:
Wojskowa Akademia Techniczna im. Jarosława Dąbrowskiego
Tematy:
mechanics
numerical simulations
aramid woven fabric
AUTODYN
Opis:
The paper presents results of experimental research and numerical analysis of the penetration process of the Twaron T750 aramid fabric with the 9 mm Parabellum projectile (brass jacket, lead core). Numerical simulations of the 9 mm Parabellum projectile impact into 10 and 16 layers of the Twaron T750 fabric with the use of the Ansys Autodyn v13 program for dynamic analyses were conducted on the basis of 3-dimensional solid numerical models. As a boundary condition in the experiment and in the numerical simulations it was assumed that all the four edges of the fabric were fixed. In the numerical simulations the sample of 50 ×50 mm dimensions and the impact velocities Vi = 448 m/s for 16 layers of the Twaron T750 fabric and Vi = 454 m/s for 10 layers of Twaron T750 fabric were adopted. In the paper the results of the numerical simulations for three material configurations with the same friction coefficients and for different values of yarn-yarn friction in case of one material configuration are presented. Residual velocity of the penetrator for the highest friction coefficient μs = 1 decreased of 13.1% in comparison to simulation with no friction (μs = 0).
Źródło:
Problemy Mechatroniki : uzbrojenie, lotnictwo, inżynieria bezpieczeństwa; 2013, 4, 3 (13); 7-22
2081-5891
Pojawia się w:
Problemy Mechatroniki : uzbrojenie, lotnictwo, inżynieria bezpieczeństwa
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Numerical and Physical Modeling of Liquid Steel Behaviour in One Strand Tundish with Gas Permeable Barrier
Autorzy:
Cwudziński, A.
Powiązania:
https://bibliotekanauki.pl/articles/354668.pdf
Data publikacji:
2018
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
tundish
gas permeable barrier
hydrodynamic conditions
numerical simulations
physical simulations
Opis:
The object of investigation was the one-strand tundish with flow control device such as gas permeable barrier (GPB). The aim of this flow control device was to activate the motion of liquid steel in the tundish longitudinal axis region. Computer simulation of the liquid steel flow and argon behaviour in isothermal turbulent motion conditions was done using the Ansys-Fluent computer program. For the validation of the hydrodynamic patterns obtained from computer simulations, a isothermal tundish glass model was used. Tundish glass model enables the recording of the visualization of fluid medium motion through the particle image velocimetry (PIV) method. Based on computer simulations, the liquid steel flow path lines in the tundish with GPB was obtained. For explain the hydrodynamic phenomena occurring in the tundish working space, the Buoyancy number has been calculated.
Źródło:
Archives of Metallurgy and Materials; 2018, 63, 2; 589-596
1733-3490
Pojawia się w:
Archives of Metallurgy and Materials
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Absolute instability of compressible three-dimensional flow
Autorzy:
Tuliszka-Sznitko, E.
Powiązania:
https://bibliotekanauki.pl/articles/1954544.pdf
Data publikacji:
1999
Wydawca:
Politechnika Gdańska
Tematy:
numerical simulations
compressible flow
instabilities
absolute instability
Opis:
In the present paper the instability character (absolute/convective) of compressible viscous flow around geometries rotating in uniform flow is analysed. The linear local stability theory is used to investigate the boundary layer stability. Following the works of Briggs and Bers in the field of plasma physics, the absolute instability region is identified by singularities of dispersion relation called pinch - points. Calculations have been made for different Mach numbers and wall temperatures.
Źródło:
TASK Quarterly. Scientific Bulletin of Academic Computer Centre in Gdansk; 1999, 3, 1; 5-16
1428-6394
Pojawia się w:
TASK Quarterly. Scientific Bulletin of Academic Computer Centre in Gdansk
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Modeling and Experimental Verification of Ultrasound Transmission in Electro Insulation Oil
Autorzy:
Wotzka, D.
Cichoń, A.
Boczar, T.
Powiązania:
https://bibliotekanauki.pl/articles/177158.pdf
Data publikacji:
2012
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
ultrasound transmission
numerical simulations
electro-insulation oil
Opis:
A verification study of ultrasound transmission numerical simulation results with experiment results is presented in this paper. The work considers a model of a transformer tank which is filled with electro insulating oil. In the experiment, performed under laboratory conditions, an ultrasound wave is generated by a piezoelectric transducer that is fixed in the centre of the tank and measured by another transducer mounted inside the tank at three distances: 10, 20 and 30 cm from the sound source. The transducer is able to measure and generate acoustic waves in the ultrasound frequency band up to 1 MHz. The simulation considers numerical calculation of acoustic pressure distribution inside the tank in which acoustic source emits waves with frequency equal to 100 kHz. Verification analysis has confirmed consistency of the numerically calculated values with the measurement results.
Źródło:
Archives of Acoustics; 2012, 37, 1; 19-22
0137-5075
Pojawia się w:
Archives of Acoustics
Dostawca treści:
Biblioteka Nauki
Artykuł
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