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    Wyświetlanie 1-7 z 7
    Tytuł:
    Experimental and numerical investigation on specimen geometry effect on the ctod value for VL-E36 shipbuilding steel
    Autorzy:
    Kowalski, Jakub
    Powiązania:
    https://bibliotekanauki.pl/articles/1955590.pdf
    Data publikacji:
    2021
    Wydawca:
    Politechnika Gdańska. Wydział Inżynierii Mechanicznej i Okrętownictwa
    Tematy:
    CTOD
    fracture toughness
    ductility
    FEM
    abaqus
    Opis:
    There are special cases in the marine industry, where additional material tests, such as the fracture toughness test, must be performed. Additional fracture toughness tests, such as CTOD (Crack Tip Opening Displacement), are typically performed on three-point bend specimens. The dimension that defines all the specimen dimensions is the thickness of the material to be tested. It is recommended by classification societies (e.g. DNVGL) to test specimens that are twice as high as the material thickness. The width determines the length and, therefore, the weight of the specimen which, for a 100 mm plate is over 140 kg. Current ASTM E1820, BS7448-1 and ISO 12135 testing standards also allow for proportions other than those recommended. This results in a much smaller test piece. Reducing the specimen size allows the testing machine to achieve lower forces than a specimen with a width to thickness ratio of two. This paper presents the effect of changing the specimen geometry on CTOD test results. Research was performed for specimens with a height to thickness ratio of one and two. Abaqus software was used for numerical calculations. The numerical results were, at selected points, verified experimentally.
    Źródło:
    Polish Maritime Research; 2021, 3; 110-116
    1233-2585
    Pojawia się w:
    Polish Maritime Research
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Experimental and numerical investigations of ultimate strength of imperfect stiffened plates of different slenderness
    Autorzy:
    Woloszyk, Krzysztof
    Garbatov, Yordan
    Kowalski, Jakub
    Samson, Leszek
    Powiązania:
    https://bibliotekanauki.pl/articles/1573852.pdf
    Data publikacji:
    2020
    Wydawca:
    Politechnika Gdańska. Wydział Inżynierii Mechanicznej i Okrętownictwa
    Tematy:
    stiffened plate
    ultimate strength
    FEM
    boundary conditions
    Opis:
    The objective of this study is to analyse the behaviour of compressed stiffened plates of different slenderness using experimental and numerical methods. The presented results are part of a long-term project to investigate the ultimate strength of geometrically imperfect structures subjected to different degradation phenomena, including corrosion degradation and locked cracks. Several specimens were subjected to a uniaxial compressive force, and the most important quantities related to the structural behaviour were captured and analysed. A finite element model, accounting for material and geometrical nonlinearities and initial geometrical imperfections, was developed using the commercial software ANSYS. The residual welding-induced stresses were measured in the middle cross-section for two specimens. The initial imperfection was identified by employing a close-range photogrammetry approach. It was concluded that the numerical analyses, based on the finite element model, predict the ultimate strength of stiffened plates accurately, although some deviations were also observed. The detailed analysis with the indication of possible uncertainty is presented, and several conclusions are derived.
    Źródło:
    Polish Maritime Research; 2020, 4; 120-129
    1233-2585
    Pojawia się w:
    Polish Maritime Research
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Influence of process of straightening ship hull structure made of 316L stainless steel on corrosion resistance and mechanical properties
    Autorzy:
    Kowalski, Jakub
    Licznerski, Łukasz
    Supernak-Marczewska, Milena
    Emilianowicz, Krzysztof
    Powiązania:
    https://bibliotekanauki.pl/articles/1573799.pdf
    Data publikacji:
    2020
    Wydawca:
    Politechnika Gdańska. Wydział Inżynierii Mechanicznej i Okrętownictwa
    Tematy:
    316L steel
    flame straightening
    corrosion resistance
    mechanical properties
    Opis:
    The AISI 316L type steel belongs to the group of chromium-nickel stainless steels. They are determined according to European standards as X2CrNiMo17-12-2 and belong to the group of austenitic stainless steels. Steels of this group are used for elements working in seawater environments, for installations in the chemical, paper, and food, industries, for architectural elements, and many others. The chemical composition of corrosion-resistant austenitic steels provides them with an austenite structure that is stable in a wide temperature range, under appropriate conditions for heating, soaking, and cooling. 316L steel plate was subjected to a technological treatment of hot straightening with an oxyacetylene torch, which is not commonly used for this type of steel, mainly due to the lack of objective assessment of whether the austenitizing temperature has been achieved and the stability of the heat treatment process is ensured. The single-phase structure of austenite with high corrosion resistance, without precipitation of carbides, steel is obtained by supersaturation in water from 1100°C. The purpose of the presented research was to determine the usefulness of the flame straightening process for a ship structure made of 316L steel.
    Źródło:
    Polish Maritime Research; 2020, 4; 103-111
    1233-2585
    Pojawia się w:
    Polish Maritime Research
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    The impact of firefighter fatigue on the quality of chest compressions during resuscitation
    Autorzy:
    Gryz, Paulina
    Kowalski, Jakub
    Leszczyński, Piotr K.
    Miftadinow, Martyna
    Szubińska, Katarzyna
    Powiązania:
    https://bibliotekanauki.pl/articles/29432048.pdf
    Data publikacji:
    2023-12
    Wydawca:
    Towarzystwo Pomocy Doraźnej
    Tematy:
    chest compressions
    firefighter
    fatigue
    quality
    Resuscitation
    Opis:
    INTRODUCTION: The effectiveness of cardiopulmonary resuscitation depends primarily on the actions taken at the scene. Firefighters are often the first ones to help the injured. The quality of their rescue efforts in such case determines the subsequent prognosis for the patient. Nevertheless, the tasks of firefighters also involve activities associated with a lot of physical activity, which can cause them to lose strength faster during CPR. The aim of the study was to assess the impact of fatigue on the quality of CPR performed by firefighters. MATERIALS AND METHODS: The study group consisted of 100 firefighters of volunteer firefighting units in the Siedlce poviat in Poland. The study was divided into three stages: I - performing chest compressions in a timed regime, II - subjecting the study group to uniform physical activity, III - reassessing the quality of chest compressions. The effectiveness of CPR was analyzed using a computer system and a professional training model. To analyze the variables, the normality of the distribution was determined using the Shapiro-Wilk test, and then the non-parametric test for uncorrelated variables Mann-Whitney U was used. Correlations were tested using the r-Pearson test at p<0.05 significance. RESULTS: The study group consisted of 93 men and 7 women, with a mean age of M=30.84 (SD ± 10.95). The respondents mostly had secondary education (42%) and vocational education (24%), with the majority (54%) declaring their marital status as single. Firefighters with varying ranks, including commanders, chiefs and presidents, participated in the study. The overall quality of chest compressions was lower each time after physical activity, at each analyzed minute of stage I and stage III (minute 1: 84.56% vs. 81.68%, p=0.281; minute 2: 81.13% vs. 80,25%, p=0,558; minute 3: 81.91% vs. 77.78%; p=0.243). A significantly higher quality of chest compressions was observed among men compared to women, both before fatigue (p=0.019) and after physical activity (p=0.053). Participants in the >53 age group had the best resuscitation scores in both during fatigue (90.78%) and before physical activity (90.83%). There was no significant correlation with rank or function of firefighters. Among the parameters of chest compressions evaluated in the third minute, the greatest effect of fatigue was shown in the aspect of the compression rate (59.42% vs. 49.20%) and depth (71.61% vs. 67.86%). CONCLUSIONS: Physical fatigue of firefighters results in moderate decrease in the effectiveness of chest compressions, especially in terms of the rate and depth of compressions. The overall quality of chest compressions is significantly higher in men than in women both before and after physical activity. The experience of firefighters can translate into the quality of resuscitation, regardless of their age.
    Źródło:
    Critical Care Innovations; 2023, 6, 4; 1-10
    2545-2533
    Pojawia się w:
    Critical Care Innovations
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Preliminary report on the microvertebrate faunal remains from the Late Triassic locality at Krasiejów, SW Poland
    Autorzy:
    Kowalski, Jakub
    Bodzioch, Adam
    Janecki, Piotr A.
    Ruciński, Maciej R.
    Antczak, Mateusz
    Powiązania:
    https://bibliotekanauki.pl/articles/191960.pdf
    Data publikacji:
    2019
    Wydawca:
    Polskie Towarzystwo Geologiczne
    Tematy:
    microvertebrates
    archosauromorphs
    fish
    amphibians
    Triassic
    Keuper
    Polska
    Opis:
    Fossil vertebrate remains from the Keuper unit in the vicinity of the village of Krasiejów have been analyzed for almost two decades. However, the main goal of these works was focused mainly on large vertebrates. Here the authors present the first description of microvertebrate fossils from that site. The collection of around 5,000 specimens is mainly comprised of teeth and scales. The most numerous remains belong to osteichthyans: dipnoans (Ptychoceratodus and cf. Arganodus), palaeoniscids, semionotids, redfieldiids and chondrichthyans, such as Lonchidion sp., which is the first indisputable record of that genus in the Upper Triassic of Poland and the first shark at the Krasiejów locality. Tetrapod fossils consist of temnospondyl amphibians, rhynchocephalian lepidosauromorphs and archosauromorphs. Among them, temnospondyl amphibian remains are the most numerous and are represented mostly by Metoposaurus. However, on the basis of diversity in tooth morphotypes, the occurrence of other taxa cannot be excluded. Rhynchocephalians are composed of 7 fragmentary jaw morphotypes with dentition, which could indicate high taxonomic diversity (cf. Planocephalosaurus, cf. Diphydontosaurus and cf. Clevosaurus). The most varied fossil group was assigned to the archosauromorphs. The authors can distinguish at least 19 teeth morphotypes, which show similarities to the dentition of: protorosaurians (cf. Tanystropheidae), pseudosuchians (cf. Protecovasaurus, cf. Revueltosaurus), early crocodylomorphs and basal sauropodomorph dinosaurs. The first occurrence of a theropod dinosaur and cynodonts at the Krasiejów locality is also recorded. However, their remains are very rare. These new records show a high taxonomic diversity at the Krasiejów locality that contributes to our deeper understanding of Late Triassic ecosystem of Poland.
    Źródło:
    Annales Societatis Geologorum Poloniae; 2019, 89, 3; 291-305
    0208-9068
    Pojawia się w:
    Annales Societatis Geologorum Poloniae
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Influence of material thickness on the ductile fracture of steel plates for shipbuilding
    Autorzy:
    Jakub, Kowalski
    Janusz, Kozak
    Powiązania:
    https://bibliotekanauki.pl/articles/32912848.pdf
    Data publikacji:
    2022
    Wydawca:
    Politechnika Gdańska. Wydział Inżynierii Mechanicznej i Okrętownictwa
    Tematy:
    ductility
    toughness
    plasticity
    CTOD
    Opis:
    In the shipbuilding industry, the risk of brittle fractures is relatively high because some units operate in arctic or subarctic zones and use high thickness (up to 100 mm) steel plates in their structures. This risk is limited by employing certified materials with a specific impact strength, determined using the Charpy method (for a given design temperature) and by exercising control over the welding processes (technology qualification, production supervision, and non-destructive tests). However, for offshore constructions, such requirements may prove insufficient. For this reason, regulations employed in constructing offshore structures require conducting crack tip opening displacement (CTOD) tests for steel and welded joints with thicknesses exceeding 40 mm for high tensile strength steel and 50 mm for other steel types. Since classification codes do not accept the results of CTOD tests conducted on specimens of sub-sized dimensions, the problem of theoretically modelling the steel construction destruction process is of key importance, as laboratory tests for notched elements of considerable thickness (100 mm and higher) are costly and problems stemming from high loads and a wide range of recorded parameters are not uncommon. The aim of this research is to find a relationship between material thickness and CTOD value, by establishing and verifying a numerical model that allows recalculating a result obtained on a sub-size specimen to a full- size specimen for a ductile fracture mode. This work presents results and conclusions from numerical modelling and compares them with laboratory test results of the elastic-plastic properties of high thickness steel, typically used in offshore applications.
    Źródło:
    Polish Maritime Research; 2022, 3; 160-166
    1233-2585
    Pojawia się w:
    Polish Maritime Research
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Application of the Raspberry Pi 4 micro-controller for the conceptual design of the baby monitor
    Zastosowanie mikrokontrolera Raspberry Pi 4 do projektu koncepcyjnego niani elektronicznej
    Autorzy:
    Kowalski, Sławomir
    Radzik, Michał
    Sromek, Jakub
    Powiązania:
    https://bibliotekanauki.pl/articles/2130868.pdf
    Data publikacji:
    2021
    Wydawca:
    Państwowa Wyższa Szkoła Zawodowa w Nowym Sączu
    Tematy:
    Raspberry Pi 4
    electronic nanny
    python
    wireless communication
    niania elektroniczna
    komunikacja bezprzewodowa
    Opis:
    The subject of the work is a conceptual design of a baby monitor. The central control system for the system is the Raspberry Pi 4 platform. In the next stages, practical aspects related to the topic of work are discussed. Selected components of the system were presented, connection diagrams between individual components were developed and the assembly process of a fully functional system was presented. Then the source code of the program controlling the operation of the electronic system was characterized. In the last stage, the method of testing and the results of the performed functional tests of the complete system being the subject of the study were described.
    Przedmiotem pracy jest projekt koncepcyjny niani elektronicznej. Centralnym systemem sterowania systemem jest platforma Raspberry Pi 4.W kolejnych etapach omawiane są praktyczne aspekty związane z tematem pracy. Przedstawiono wybrane elementy systemu, opracowano schematy połączeń pomiędzy poszczególnymi elementami, a także proces montażu w pełni funkcjonalnego systemu. Następnie scharakteryzowano kod źródłowy programu sterującego pracą układu elektronicznego. W ostatnim etapie opisano metodę testowania i wyniki przeprowadzonych testów funkcjonalnych kompletnego systemu będącego przedmiotem badań.
    Źródło:
    Journal of Engineering, Energy and Informatics; 2021, 1; 43-52
    2720-4162
    2720-5541
    Pojawia się w:
    Journal of Engineering, Energy and Informatics
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
      Wyświetlanie 1-7 z 7

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