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Wyszukujesz frazę "Marek, Adam." wg kryterium: Autor


Wyświetlanie 1-6 z 6
Tytuł:
Performance of artificial neural networks in an inverse problem of laser beam diagnostics
Autorzy:
Pietrak, Karol
Muszyński, Radosław
Marek, Adam
Łapka, Piotr
Powiązania:
https://bibliotekanauki.pl/articles/2173550.pdf
Data publikacji:
2022
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
inverse problems
pattern recognition
laser beams
odwrotne problemy
rozpoznawanie wzorców
wiązka laserowa
Opis:
The presented results are for the numerical verification of a method devised to identify an unknown spatio-temporal distribution of heat flux that occurs at the surface of a thin aluminum plate, as a result of pulsed laser beam excitation. The presented identification of boundary heat flux function is a part of the newly proposed laser beam profiling method and utilizes artificial neural networks trained on temperature distributions generated with the ANSYS Fluent solver. The paper focuses on the selection of the most effective neural network hyperparameters and compares the results of neural network identification with the Levenberg–Marquardt method used earlier and discussed in previous articles. For the levels of noise measured in physical experiments (0.25–0.5 K), the accuracy of the current parameter estimation method is between 5 and 10%. Design changes that may increase its accuracy are thoroughly discussed.
Źródło:
Bulletin of the Polish Academy of Sciences. Technical Sciences; 2022, 70, 1; e140100, 1--11
0239-7528
Pojawia się w:
Bulletin of the Polish Academy of Sciences. Technical Sciences
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Effect of hot deformation and isothermal holding temperature on retained austenite characteristics in 3-5% Mn multiphase steels
Autorzy:
Opiela, Marek
Grajcar, Adam
Pakieła, Wojciech
Powiązania:
https://bibliotekanauki.pl/articles/2204525.pdf
Data publikacji:
2023
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
hot deformation
bainitic transformation
retained austenite
Mn effect
multiphase structure
manganese effect
austenit szczątkowy
struktura wielofazowa
efekt Mn
odkształacanie wysokotemperaturowe
przemiana bainityczna
Opis:
The paper presents stress-strain characteristics recorded during the four-step compression of axisymmetric samples in the Gleeble thermomechanical simulator. The hot deformability of three steels with Mn concentrations of 3%, 4% and 5% was compared. The analysis of the influence of plastic deformation and Mn content on the microstructure of alloys, and in particular, on a fraction and morphological features of the retained austenite, was performed. The proportion of the retained austenite was determined by the X-ray diffraction method. It was found that the content of Mn in the range from 3% to 5% does not have a significant impact on the high-temperature resistance of the steel during compression tests, but it has a significant influence on the microstructure of the steel and the fraction of retained austenite. The optimal conditions for maximizing the proportion of retained austenite were obtained at the temperature of 400 °C, and it decreased with increasing Mn concentration in the steel. It has been shown that it is related to the redistribution of carbon from the remaining austenite fraction with an increase in the manganese content. The mechanical properties were determined on the basis of hardness measurements.
Źródło:
Bulletin of the Polish Academy of Sciences. Technical Sciences; 2023, 71, 2; art. no. e144611
0239-7528
Pojawia się w:
Bulletin of the Polish Academy of Sciences. Technical Sciences
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Analysis of the precipitation process of secondary phases after long-term ageing of the S304H steel
Autorzy:
Zieliński, Adam
Wersta, Robert
Sroka, Marek
Powiązania:
https://bibliotekanauki.pl/articles/2086867.pdf
Data publikacji:
2021
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
S304H steel
microstructure
precipitates
ageing
loss of durability
stal S304H
mikrostruktura
wytrącanie
starzenie
utrata trwałości
Opis:
S304H steel is used in the construction of pressure components of boilers with supercritical operating parameters. The paper presents the results of research on the microstructure following ageing for 30,000 hours at 650 and 700°C. Microstructure examination was performed using scanning and transmission electron microscopy. The precipitates were identified using transmission electron microscopy. The paper analyses the precipitation process and its dynamics depending on the temperature and ageing time in detail. MX carbonitrides and the ε_Cu phase were proved to be the most stable phase, regardless of the test temperature. It was also showed that the M₂₃C₆ carbide precipitates in the tested steel and the intermetallic sigma phase (σ) may play a significant role in the loss of durability of the tested steel. This is related to their significant increase due to the influence of elevated temperature, and their coagulation and coalescence dynamics strongly depend on the ageing/operating temperature level. The qualitative and quantitative identification of the secondary phase precipitation processes described in the study is important in the analysis of the loss of durability of the tested steel under creep conditions.
Źródło:
Bulletin of the Polish Academy of Sciences. Technical Sciences; 2021, 69, 5; e137520, 1--7
0239-7528
Pojawia się w:
Bulletin of the Polish Academy of Sciences. Technical Sciences
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Mechanical properties of Super 304H steel after long-term ageing at 650 and 700°C
Autorzy:
Zieliński, Adam
Sroka, Marek
Purzyńska, Hanna
Novy, Frantisek
Powiązania:
https://bibliotekanauki.pl/articles/2204537.pdf
Data publikacji:
2023
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
Super 304H steel
mechanical properties
ageing
stal Super 304H
właściwości mechaniczne
starzenie się
Opis:
The paper shows the degradation process of the modern austenitic Super 304H (X10CrNiCuNb18-9-3) steel which was subjected to long-term aging for up to 50,000 h at 650 and 700°C. The investigations include microstructure examination (SEM), identification and analysis of the precipitation process, and mechanical properties tests. The Super 304H steel has a structure characteristic of austenitic steels with visible annealing twins and single primary NbX precipitates. Long-term aging in the steel leads to numerous precipitation processes of M23C6, MX carbides, σ phase, Z phase, and ε-Cu phase. Precipitation processes lead to a decrease in plastic properties and impact energy as well as alloy over aging. Yield strength and tensile strength values after 50,000 h of aging were similar to those as delivered. The yield and tensile strength value strongly depend on the applied aging temperature.
Źródło:
Bulletin of the Polish Academy of Sciences. Technical Sciences; 2023, 71, 2; art. no. e144612
0239-7528
Pojawia się w:
Bulletin of the Polish Academy of Sciences. Technical Sciences
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Research of damage to the rear wheel rim in a tipper-truck
Autorzy:
Kubiak, Przemyslaw
Wozniak, Marek
Zakrzewski, Sergiusz
Siczek, Krzysztof
Rylski, Adam
Mrowicki, Adam
Matej, Jan
Deda, Jakub
Knap, Lech
Powiązania:
https://bibliotekanauki.pl/articles/2173686.pdf
Data publikacji:
2022
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
tipper-truck
rim
tire
failure
wywrotka
obręcz
opona
awaria
Opis:
Serious damage to the inner rim of the rear twin wheel in one dump truck was noted during the operation of the fleet performing transport tasks. It was a drive wheel, and its damage occurred while driving with a load exceeding the permissible value. The examination of selected fragments of the damaged rim surface was conducted visually as well as using a digital microscope with a portable head. The measurements of the Vickers hardness and microscopic observations of the material structure of the sample cut along the thickness of the rim disk were carried out. The drive torque loading of the twin wheels of the tipper-truck rear axle, under their mating with different kinds of road roughness and under various vertical loads of the wheels was calculated. An analysis of stress distributions in the rim modelled using the Finite Element Method was also conducted for several possible scenarios of wheel loading. The damage to the rim was caused by simultaneous action of several factors, such as overloading the car, poor condition of the tires, loading the drive wheel by a part of the vehicle weight and the driving torque, and hitting a wheel on a cavity in a dirt road, causing a temporary relief of one of the tires on a twin wheel.
Źródło:
Bulletin of the Polish Academy of Sciences. Technical Sciences; 2022, 70, 3; art. no. e141000
0239-7528
Pojawia się w:
Bulletin of the Polish Academy of Sciences. Technical Sciences
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Approximation models for the evaluation of TCP/AQM networks
Autorzy:
Marek, Dariusz
Domański, Adam
Domańska, Joanna
Szyguła, Jakub
Czachórski, Tadeusz
Klamka, Jerzy
Filus, Katarzyna
Powiązania:
https://bibliotekanauki.pl/articles/2173690.pdf
Data publikacji:
2022
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
diffusion approximation
active queue management
AQM
congestion control
dropping packets
fluid flow approximation
FFA
non-integer order PIγ controller
G/G/1/N queueing model
przybliżenie dyfuzji
aktywne zarządzanie kolejką
kontrola zatorów
upuszczanie pakietów
przybliżenie przepływu płynu
model kolejkowania G/G/1/N
Opis:
The article proposes a model in which Diffusion Approximation is used to analyse the TCP/AQM transmission mechanism in a multinode computer network. In order to prevent traffic congestion, routers implement AQM (Active Queue Management) algorithms. We investigate the influence of using RED-based AQM mechanisms and the fractional controller PIγ on the transport layer. Additionally, we examine the cases in which the TCP and the UDP flows occur and analyse their mutual influence. Both transport protocols used are independent and work simultaneously. We compare our solution with the Fluid Flow approximation, demonstrating the advantages of Diffusion Approximation.
Źródło:
Bulletin of the Polish Academy of Sciences. Technical Sciences; 2022, 70, 4; art. no. e141986
0239-7528
Pojawia się w:
Bulletin of the Polish Academy of Sciences. Technical Sciences
Dostawca treści:
Biblioteka Nauki
Artykuł
    Wyświetlanie 1-6 z 6

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