Autor: Majewski, J - Katalog OPAC zbiorów

Skocz do pozycji: 1.

Tytuł:: Selected problems of experimental investigation of dynamically loaded journal bearings
Autorzy:: Sikora, J.
Kłopocki, J.
Majewski, W.
Powiązania:: https://bibliotekanauki.pl/articles/242758.pdf
Data publikacji:: 2007
Wydawca:: Instytut Techniczny Wojsk Lotniczych
Tematy:: combustion engine
engine parts
bearings
tribology
bearing fatigue
Opis:: In the paper some problems concerning relations between external bearing loadings and critical lining stresses are described for test stand with rotating load vector. According to the standard ISO 7905/1 this type of test stand, for dynamically loaded slide bearing, is recommended as a basic research unit for material testing in a complete bearing unit. The lining stress calculation results occurred being dependent on applied calculation model. The influence of sliding surface shape and housing stiffness on bearing fatigue have been considered. The MWO-stand operational principle, standard tested half-bearing, bearing housing of rigid profile, bearing housing of edge elastic profile, distribution of radial and circumferential stress in the slide layer of the bearing bush tested in MWO stand, typical damage of the bearing tested, finite element model geometry for bush and housing are illustrated in the paper. Performed calculations revealed that neglecting the shape and dimensions of the housing in calculation model of the contemporary thin-walled multilayer bearing bushes are leading to incorrect evaluation of critical stresses leading to fatigue cracks in slide layers of the bearing tested in machines with rotary load vector. That kind of bearing alloys is not employed in highly dynamically loaded bearings of contemporary machines, especially in IC engine bearing systems.
Źródło:: Journal of KONES; 2007, 14, 4; 433-440
1231-4005
2354-0133
Pojawia się w:: Journal of KONES
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 2.

Tytuł:: Mechanism of the fatigue cracks development in bearing slide layer
Autorzy:: Sikora, J.
Kłopocki, J.
Majewski, W.
Powiązania:: https://bibliotekanauki.pl/articles/245360.pdf
Data publikacji:: 2009
Wydawca:: Instytut Techniczny Wojsk Lotniczych
Tematy:: bearings
bearing slide layer
fatigue cracks
fracture mechanics
lubrication
fractography
Opis:: In the paper some problems concerning relations between slide bearings fatigue resistance and the bearing material and structure characteristics of the slide layer have been considered on the basis of bibliographic descriptions. In particular the mechanisms of the nucleation and development of cracks were discussed as dependent not only on the bearing dynamic loading pattern and number of loading cycles but also on the slide layer geometry and its structure design. Two basic types of the possible fatigue cracks were distinguished: structural and "magistral" ones. The process of the fatigue rapture formation and development were analyzed from the viewpoint of fracture mechanics according to the Nemec 's model. In particular types of fatigue cracks, structural cracks (cross-section of the bearing surface layer) and mechanism of fatigue crack development from the viewpoint of fracture mechanics, as well as fracture of magistral type (on the surface of the bearing) almost perpendicular to the circular direction of the bush, fatigue durability for various types of fracture developments, Fractures on the boundary of Si particle in AlSnl2 Si4 alloy and Sn particle in AlSn20 alloy, fractures on the boundary of the intermetallic compound grain CuAl2 in AlSn20 alloy are presented in the paper.
Źródło:: Journal of KONES; 2009, 16, 4; 423-427
1231-4005
2354-0133
Pojawia się w:: Journal of KONES
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 3.

Tytuł:: Fatigue resistance investigation of the IC engine MB11 bearings, working under conditions of dynamic unidirectional loadings
Autorzy:: Sikora, J.
Kłopocki, J.
Majewski, W.
Powiązania:: https://bibliotekanauki.pl/articles/243868.pdf
Data publikacji:: 2008
Wydawca:: Instytut Techniczny Wojsk Lotniczych
Tematy:: transport
plain bearings
bearings testing
bearings fatigue
Opis:: The slide bearing material MB11 fatigue resistance has been investigated with the application of SMOK - test stand in which dynamic unidirectional loadings to the test bearing is generated. Slide bearing layer consists of the bronze (Cu Pb22 Sn 3) sintered to the steel shell. Each of the tested bearing has been subject to the standard 20-hour test, under conditions of the full fluid lubrication. Methodology of the experiments, metallurgical test results and fractographic description of the lining fatigue crack zone are presented. The values of the fatigue strength parameters are also estimated. For the loading pattern that is characteristic for the test devices such as SMOK tester, because of the nominally negative high normal stresses in the damage area, the mechanisms of cracks generation could be explained as follows: yield stress can be reached when during compression at the bearing working temperature the local plastic deformation can appear. After completing the test, in the region of plastic deformation, the tensile stresses can be generated due to the temperature reduction. Slide material is much more sensitive to the tensile loadings than to the compressive one, especially in the area that is weaken by empty spaces. That might be reason for cracks generation. Additionally in the case of the thin-wall bearing shell, assembled in the elastic housing, the circumferentially oriented cracks can appear. It has been observed for high bearing loadings applied on the SMOK tester. Fatigue cracks in the MB11 material tested on the SMOK machine are of the surface net pattern, positioned paralleled to the slide surface (Fig. 8). Mainly structural cracks can be noticed when analyzing the metallographic description. This is related to the porosity of the alloy structure. This is much different from the aluminum alloy structure (the bearing alloy that was previously investigated) where arterial structures of cracks were dominant. The slide surface is the place of cracks nucleation. When in slide layer there are bigger soft material elements or voids it is also possible to observe generation of cracks in any place of the bulk thickness. During consequent development of the process the micro-cracks are spreading out and going to the next defected parts of the alloys. The continuous surface of separation is then developed. The micro-cracks space net which is typical for this kind of damage is not precisely oriented but rather random. The eventually oriented fracture is due to the not uniform structure.
Źródło:: Journal of KONES; 2008, 15, 2; 449-456
1231-4005
2354-0133
Pojawia się w:: Journal of KONES
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 4.

Tytuł:: Zastosowanie analiz kopalnego DNA w badaniach osadów czwartorzędowych
Applications of sedimentary ancient DNA analyses in geological Quaternary research
Autorzy:: Demianiuk, E. J.
Majewski, W.
Powiązania:: https://bibliotekanauki.pl/articles/2075809.pdf
Data publikacji:: 2018
Wydawca:: Państwowy Instytut Geologiczny – Państwowy Instytut Badawczy
Tematy:: analiza kopalnego DNA
sekwencjonowanie nowej generacji
NGS
paleogenetyka
paleośrodowisko
paleobioróznorodność
sedimentary ancient DNA
Next Generation Sequencing
paleogenetic
paleoenvironments
paleobiodiversity
Opis:: During the past few decades genetic research has been developed in parallel with paleogenetics. A dynamic progress in this field of studies is possible due to the advance in laboratory and computer technologies. Today, scientists have the Next Generation Sequencing methods at their disposal, which enable them to read millions ofsequences at the same time, thus furthermore significantly reducing time needed for laboratory procedures. Concurrently, costs of analysis and equipment have been decreasing, which makes paleogenetical analyses widely available. They are commonly used in medicine, biotechnology, genetic engineering, food industry and forensics, as well as in life sciences like biology, paleobiology, archeology, geology and environmental protection sciences. This paper presents seda DNA (sedimentary ancient DNA) analyses and their use in Quaternary research, as well as describes sources of DNA in sediments and main processes contributing to its degradation or preservation.
Źródło:: Przegląd Geologiczny; 2018, 66, 11; 680--691
0033-2151
Pojawia się w:: Przegląd Geologiczny
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 5.

Tytuł:: Some problems of slide bearing material fatigue evaluation
Autorzy:: Sikora, J.
Kłopocki, J.
Majewski, W.
Kurzych, K.
Powiązania:: https://bibliotekanauki.pl/articles/242756.pdf
Data publikacji:: 2007
Wydawca:: Instytut Techniczny Wojsk Lotniczych
Tematy:: bearings
tribology
bearing testing
fatigue investigations
fatigue performance
Opis:: A slide bearing alloy resistance against fatigue failures have been investigated for three different lubricants, different heat loadings and different stress ratio K values. The research methods and data handling procedures for determination of particular parameter effects on fatigue strength have been described and analysed for experiments that were set and performed in laboratory tester SKMR-2. Main and interaction effects of lubricant and stress ratio factors on bearing material fatigue strength have been analysed. Design scheme of the SKMR-2 head unit, Standard tested half-bearing, fatigue failures on the surface of the specimen, cross-section through the damaged surface layer of the specimen, fatigue limit stress amplitude vs. temperature and kind of oil, main effect of stress ratio, main effects of temperature and oil are illustrated in the paper. Main conclusions are cover in statements that fatigue strength of the bearing material is affected, to the highest degree, by the mechanical stress value and stress ratio and resistance to the fatigue cracks is being reduced for higher tensional stress, increase in temperature is resulting in decreasing of the fatigue strength rating values, fatigue strength of the slide layer is considerably dependent on the type of the used lubricant interactions of the type of the lubricants, their temperatures, loading stress ratio have been noticed.
Źródło:: Journal of KONES; 2007, 14, 4; 427-432
1231-4005
2354-0133
Pojawia się w:: Journal of KONES
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 6.

Tytuł:: Ocena równowagi hydrodynamicznej Dolnego Dunajca w warunkach pracy elektrowni wodnych
The estimation of hydrodynamical balance of the Lower Dunajec below hydro-energy power plant
Autorzy:: Bartnik, W.
Majewski, W.
Lapuszek, M.
Ratomski, J.
Powiązania:: https://bibliotekanauki.pl/articles/60754.pdf
Data publikacji:: 2007
Wydawca:: Polska Akademia Nauk. Stowarzyszenie Infrastruktura i Ekologia Terenów Wiejskich PAN
Tematy:: rzeki
rzeka Dunajec
erozja denna
rownowaga hydrodynamiczna
przeplyw wody
male elektrownie wodne
Opis:: Dunajec jest jedną z większych rzek polskich z dużym zagrożeniem powodziowym i potencjałem hydroenergetycznym. Wybudowane zostały dwie wielkie zapory dla ochrony przeciwpowodziowej. z wykorzystaniem hydroenergetycznym piętrzenia wody w tych zbiornikach. W 1997 r. oddano do eksploatacji zaporę, zbiornik wodny i elektrownię Czorsztyn-Niedzica. W konsekwencji budowy zapór i zbiorników Czorsztyn-Niedzica oraz Rożnów zatrzymany został prawie całkowicie transport rumowiska, co spowodowało ciągłą erozję dna Dunajca poniżej Czchowa na odcinku 67,4 km. W chwili obecnej Dunajec ma charakter drenującej rzeki. W związku ze stale postępującą erozją denną poniżej Czchowa lokalnie do 4 m dla zatrzymania tego procesu i odtworzenia warunków położenia dna z okresu poprzedzającego budowę zbiorników, powstała koncepcja stabilizacji tego odcinka progami niskiego spadu. Progi stabilizacyjne będą mogły być wykorzystane do lokalizacji małych elektrowni wodnych, które będą pracować na średnim przepływie [Praca zbiorowa 2006].
The one of the Polish rivers richest in water with substantial flood hazard and important hydro-energy potential. Two large flood protection and hydroenergy schemes were constructed on the Upper Dunajec: Rożnów-Czchów and Czorsztyn-Sromowce Wyżne. Lower Dunajec extends downstream from the Czchów hydraulic barrage to the outflow to the Vistula and is 67.4 km long. Construction of two large hydraulic schemes resulted in the increase of the low and average discharges, however, simultaneously important disturbance of sediment transport occurred. A large amount of sediment is deposited in the reservoirs. As the result of this process, significant erosion was observed along the Lower Dunajec reaching in some places even 4 m. This process was increased by the sediment exploitation from the river channel. Due to flood problems several training works were executed along the Lower Dunajec. All these resulted in lowering of the river channel, which became a draining river. Stabilization of the river channel is possible by means of the construction of special weirs with inflatable gates. Construction of the weirs gives the possibility of using heads for hydro-energy. It is proposed to construct small hydraulic power plants, which would operate during low and average discharges.
Źródło:: Infrastruktura i Ekologia Terenów Wiejskich; 2007, 4/1
1732-5587
Pojawia się w:: Infrastruktura i Ekologia Terenów Wiejskich
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 7.

Tytuł:: Laser welding with micro-jet cooling for truck frame welding
Autorzy:: Piwnik, J.
Szczucka-Lasota, B.
Węgrzyn, T.
Majewski, W.
Powiązania:: https://bibliotekanauki.pl/articles/374964.pdf
Data publikacji:: 2017
Wydawca:: Politechnika Śląska. Wydawnictwo Politechniki Śląskiej
Tematy:: truck frames
exploitation conditions
safety conditions
welding
alloy elements
micro-jet technology
rama samochodu ciężarowego
warunki eksploatacji
warunki bezpieczeństwa
spawanie
pierwiastek stopowy
technologia mikrojetowa
Opis:: The aim of this paper is to analyse the mechanical properties of the weld steel structure of car body truck frames after laser welding. The best welding conditions involve the use of proper materials and alloy elements in steel and filer materials, in addition to welding technology, state of stress and temperature of exploitation. We present for the first time the properties of steel track structures after laser welding with micro-jet cooling. Therefore, good selection of both welding parameters and micro-jet cooling parameters is very important to achieve a proper steel structure. In this study, the metallographic structure, tensile results and impact toughness of welded joints have been analysed in terms of welding parameters.
Źródło:: Transport Problems; 2017, T. 12, z. spec.; 107-114
1896-0596
2300-861X
Pojawia się w:: Transport Problems
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 8.

Tytuł:: The impact of gas on the tribological properties of steel 16MnCr5 after surfacing with micro-jet cooling
Autorzy:: Tarasiuk, W.
Piwnik, J.
Hornik, A.
Węgrzyn, T.
Majewski, W.
Powiązania:: https://bibliotekanauki.pl/articles/244978.pdf
Data publikacji:: 2016
Wydawca:: Instytut Techniczny Wojsk Lotniczych
Tematy:: wear resistance
steel 16MnCr5
micro-jet
surfacing
Opis:: This paper presents results of experimental research concerning the impact of an innovative method of micro-jet cooling on the padding weld performed with MAG welding. It enables to steer the parameters of weld cooling in a precise manner. Micro-jet cooling is a novel method patented in 2011. In addition, various elements, which may e.g. enhance hardness or alter tribological properties, can be entered into its top surface, depending on the applied cooling gas. The micro-jet welding method is the innovative method, which reduces the intensity of abrasive wear. The method can be used as a basic finishing or a regeneration method. An innovative technology for micro-jet is used to cool the weld surface that is, using a micro-welding jet cooling. This allows accurate and complete control of the surface structure of the deposit. The material under study was steel 16MnCr5, which was subject to the welding process with different gases of micro-jet cooling. Nitrogen and air was used as a cooling gas. The main parameter of weld assessment was wear intensity. The tests were conducted in a tribological pin-on-disc type position. T-11 pin-on-disc tester allows for indicating basic wear parameters (wear intensity, wear coefficient, wear force). Based on results of experiment the application of nitrogen in micro-jet cooling of the padding weld in the welding process of steel 16MnCr5 beneficially affects resistance to abrasive wear.
Źródło:: Journal of KONES; 2016, 23, 4; 541-548
1231-4005
2354-0133
Pojawia się w:: Journal of KONES
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 9.

Tytuł:: Electrodes with various amount of nickel for truck frame repairs
Elektrody otulone do napraw ram pojazdów ciężarowych
Autorzy:: Miros, M.
Majewski, W.
Piwnik, J.
Węgrzyn, T.
Konopka, A.
Powiązania:: https://bibliotekanauki.pl/articles/374479.pdf
Data publikacji:: 2016
Wydawca:: Politechnika Śląska. Wydawnictwo Politechniki Śląskiej
Tematy:: truck frames
exploitation
safety
welding
electrodes
alloy elements
ramy pojazdów ciężarowych
eksploatacja
bezpieczeństwo
spawanie
elektrody
elementy stopowe
Opis:: The goal of this paper is to analyze the exploitation and safety conditions of weld steel structure of car body truck frames after welding repairs made by covered electrodes. The main role of conditions in connected with materials, alloy elements in steel and filer materials, welding technology, state of stress and temperature. Because of that, good selection of steel and choice of welding method for proper steel structure repairs are very important. For responsible steel, structures like truck frames and low alloy steel are used, very often with small amounts of carbon and some amounts of alloy elements such as Ni and Mo in low alloy steel and their welds. To study the frame’s flexibility and resistance, welded joints have been analyzed. Samples have been welded by steel electrodes with various amounts of Ni.
Celem artykułu jest analiza właściwości eksploatacyjnych oraz bezpieczeństwa naprawianych ram pojazdów ciężarowych z użyciem spawania. Ważną rolę odgrywają połączenia materiałów, pierwiastki stopowe, materiały dodatkowe, technologia spawania, stan naprężeń oraz temperatura. Bardzo istotne są odpowiedni dobór stali oraz metody spawalniczej. Na odpowiedzialne konstrukcje stalowe, jak np. ramy pojazdów ciężarowych, jest używana niskostopowa stal, często z niską zawartością węgla oraz dodatkiem pierwiastków stopowych, takich jak Ni oraz Mo. Do oceny elastyczności oraz wytrzymałości połączeń spawanych w ramach pojazdów ciężarowych, analizowano właściwości połączeń wykonanych elektrodami o różnej zawartości Ni.
Źródło:: Transport Problems; 2016, 11, 4; 21-27
1896-0596
2300-861X
Pojawia się w:: Transport Problems
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 10.

Tytuł:: Sand removal from sandstone cliffs as the main factor influencing properties of organic soils - a case study of transitional Bog in the Stolowe Mountains
Autorzy:: Glinka, B.
Waroszewski, J.
Bogacz, A.
Majewski, W.
Kaczmarek, T.
Gajewski, P.
Kaczmarek, Z.
Powiązania:: https://bibliotekanauki.pl/articles/905443.pdf
Data publikacji:: 2017
Wydawca:: Uniwersytet Marii Curie-Skłodowskiej. Wydawnictwo Uniwersytetu Marii Curie-Skłodowskiej
Opis:: With this paper we investigate the effect of sand contribution to organic soils and direct influence of this process on the physical and physicochemical properties on the example of transitional bog in the Stołowe Mountains (the Central Sudetes), which was periodically covered by sand material from sandstone cliffs weathering. Field survey and soil sampling were conducted in August 2015 in the area of Białe Skały. Soil material for laboratory analysis was collected from three peat cores, while soil samples were collected from each soil horizon distinguished in each core. Obtained results indicate the great impact of mineral material admixture on soil properties, both physicochemical and chemical. Recorded values of each soil parameter in the organic horizons adjacent to the mineral interlayers differ considerably from those obtained in the soil profile free of sand admixtures. Preliminary study of soil cover of transitional bog will allow correct planning of palaeoecological research about genesis and evolution of this peatland.
Źródło:: Polish Journal of Soil Science; 2017, 50, 1
0079-2985
Pojawia się w:: Polish Journal of Soil Science
Dostawca treści:: Biblioteka Nauki

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