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Search results for: shaft%20journal
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Air journal bearing utilizing near-field acoustic levitation: stationary shaft case
PublicationResults of a study to examine a unique idea of self-levitating journal bearing are presented in this paper. the idea represents a radical departure from the current bearing technology. it utilisesacoustic levitation, which relies on the sound energy radiated by an object supporting a load. acoustic levitation has been demonstrated to support loads of up to 10 kg. in order to support a load theacoustic wave emitted by the radiating...
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Problems of Flaking in Strengthening Shaft Burnishing
PublicationThe article presents the results of testing the surface condition of shafts manufactured by a strengthening rolling burnishing process. The shafts with a hardness about 220 HB were burnished with a roller with different force. Researches were carried out with particular attention to the structure of the outflowing material in the tool zone during burnishing process. The article presents the results of the examinations of burnished...
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Sawing accuracy on the twin shaft multi-rip saw
PublicationW pracy przedstawiono analizę i wyniki badań doświadczalnych dokładności przecinania na dwuwrzecionowej pilarce tarczowej. Zaprezentowano warianty struktury geometryczno-ruchowej dwuwrzecionowej pilarki tarczowej, jak również warunki pracy dolnych górnych pił pilarki.
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Analysis of ship shaft line coupling bolts failure
PublicationW artykule przedstawiono dane statystyczne dotyczące uszkodzeń linii wałów okrętowych, w tym także pęknięć zmęczeniowych śrub sprzęgieł kołnierzowych wałów. Wyjaśniono także mechanizm powstawania tego typu uszkodzeń i zagrożenia jakie niosą ze sobą. Opisano przypadki takich uszkodzeń oraz badania jakie są prowadzone dla lepszego poznania zjawisk zmęczeniowych w omawianych uszkodzeniach.
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TWO-SHAFT GAS TURBINE TEACHING AND TESTING STATION
PublicationThe station was established as part of a project co-financed by the European Union with the funds of the European Regional Development Fund as part of the Infrastructure and Environment Operational Programme titled: “Establishment of state-of-the-art technical infrastructure for the Engineers of the Future learning programme at the Gdańsk University of Technology” executed in 2013-2015.
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ENERGY ANALYSIS OF PROPULSION SHAFT FATIGUE PROCESS IN ROTATING MECHANICAL SYSTEM PART I TESTING SIGNIFICANCE OF INFLUENCE OF SHAFT MATERIAL FATIGUE EXCITATION PARAMETERS
PublicationThe article discusses the problem of mathematical modelling of energy conversion processes in a rotating mechanical system for the purpose of identifying fatigue states of propulsion shafts in this system. A simplified physical model of the analysed system, constructed in an appropriate scale, has made the basis for the experimental research. The research programme took into consideration mechanical fatigue excitation of the model...
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ENERGY ANALYSIS OF THE PROPULSION SHAFT FATIGUE PROCESS IN A ROTATING MECHANICAL SYSTEM PART II IDENTIFICATION STUDIES – DEVELOPING THE FATIGUE DURABILITY MODEL OF A DRIVE SHAFT
PublicationThe article presents a continuation of research carried out concerning identification of energy consequences of mechanical fatigue within a propeller shaft in a rotating mechanical system, while working under conditions of the loss of the required alignment of shaft lines. Experimental research was carried out on a physical model reflecting a full-sized real object: i.e., the propulsion system of the ship. It is proven, by means...
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Scale effect in shaft friction from direct shear tests
PublicationPrzeanalizowano wartości maksymalne tarcia uzyskane w aparacie bezpośredniego ścinania w kontakcie konstrukcja-grunt dla piasków kwarcowych i węglanowych oraz gładkiego i szorstkiego kontaktu. Badania przeprowadzono przy regulowanej sztywności normalnej kontaktu, przy różnej składowej normalnej naprężenia w kontakcie i różnym zagęszczeniu gruntu. Określono efekt skali jako stosunek wartości tarcia mobilizowanego na modelu do tarcia...
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The influence of variants of finishing machining on scheduling of shaft components manufacturing
PublicationIn the paper variants of technological processes were presented to the study for piston rods and rams of hydraulic cylinders taking issues into consideration scheduling of course of the production in flexible manufacturing cell. At the carried study an attempt of the estimation of the influence of technological variants on the effectiveness to manufacture the flexible manufacturing system on the basis of preliminary schedules of...
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Shaft friction from the DMT and direct shear interface tests
PublicationThe article presents preliminary attempt to create tri-linear transfer curves for describing pile behaviour under axial loading. Transfer curves would use the parameter measured in dilatometer test, particularly a constrained modulus MDMT. The proposed method is based on concrete rough and smooth interface tests performed in a direct shear apparatus. Based on the obtained mobilization curves, relationships were created between...
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The Possibilities of Improving the Fatigue Durabilityof the Ship Propeller Shaft by Burnishing Process
PublicationHeavily loaded structural elements operating in a corrosive environment are usuallyquickly destroyed. An example of such an element is a ship propeller operating in a seawaterenvironment. This research presents a fatigue resistance test performed on elements operating inseawater. Different processing parameters applied on the samples in particular were compared withthe specimens whose surface had been burnished differently and...
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Reliability model of two-shaft turbine combustion engine with heat regenerator
PublicationW artykule przedstawiono możliwość zastosowania teorii procesów semimarkowskich do opisu niezawodności turbinowego silnika spalinowego. Opracowano model niezawodnościowy w formie siedmiostanowego procesu semimarkowskiego, umożliwiający określenie prawdopodobieństw przebywania silnika w stanie zdatności oraz wyróżnionych stanach niezdatności.
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Analysis of Failures of High Speed Shaft Bearing System in a Wind Turbine
PublicationDuring the operation of wind turbines with gearbox of traditional configuration, consisting of one planetary stage and two helical stages high failure rate of high speed shaft bearings is observed. Such a high failures frequency is not reflected in the results of standard calculations of bearing durability. Most probably it can be attributed to atypical failure mechanism. The authors studied problems in 1.5 MW wind turbines of...
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ANALYSIS OF THE POSSIBILITIES OF HIGH SPEED SHAFT BEARING SYSTEM DURABILITY INCREASE
PublicationDuring the operation of wind turbines with a gearbox of traditional configuration, a high failure rate of high-speed shaft bearings is observed. Such a high failures frequency is not reflected in standard bearing durability calculation methods, which can be attributed to atypical failure mechanism. To avoid observed problems in the 1.5 MW wind turbine, the modification of the existing bearing system is proposed. Multiple options,...
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A COMPARISON OF WEAR PROPERTIES OF WATER LUBRICATED NBR AND PTFE SLIDING BEARINGS
PublicationThe excessive wear of a journal shaft can be caused by many factors, for example, working conditions (e.g., temperaturę, slip speed, the type of lubricant), pressure, the type of material used on the bearings and shafts and their roughness, as well as contamination remaining in the system. This paper presents the roughness profiles co-operating with a rubber (NBR) and polytetrafluoroethylene (PTFE) bushes. The conditions of cooperation...
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Shift invariant operators and a saturation theorem.
PublicationPraca jest kontynuacją wcześniejszych dwóch prac wydanych w Appl. Math. w latach 2001 i 2002. Główny wynik dotyczy wygładzania specjalnego ciągu zbieżnego słabo, tak iż dostajemy ciąg zbieżny w normie supremum.
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Environmentally friedly propeller shaft support with the use of water lubricated foil bearings
PublicationW pracy przedstawiono podsumowanie prowadzonych badań w celu opracowania oryginalnej metodyki projektowania oraz technologii wykonania pierwszego w świecie łożyska foliowego smarowanego wodą. Zaprezentowano koncepcje nowego łożyska foliowego poprzecznego oraz opisano opracowany algorytm obliczeniowy wykorzystany do predykcji jego charakterystyk. W rezultacie prowadzonych prac opracowano i przebadano doświadczalnie na stanowisku...
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OPERATION OF TWO-SHAFT GAS TURBINE IN THE RANGE OF OPEN ANTI-SURGE VALVE
PublicationThis paper presents experimental tests of full-scale two-shaft gas turbine in the range of open anti-surge valve (ASV). The tests were carried out in a laboratory gas- turbine test stand belonging to Department of Automation and Power Engineering , Faculty of Ocean Engineering and Ship Technology , Gdańsk University of Technology. The tests covered the start-up and low load operation of the turbine set in the range of open...
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A method to assess transverse vibration energy of ship propeller shaft for diagnostic purposes
PublicationThe article discusses a key problem of ship propulsion system vibration diagnostics, which concerns assessing this part of mechanical energy transmitted from the main engine to the ship propeller which is dissipated due to propeller shaft vibration. A simplified calculation model is proposed which allows the total energy of the generated torsional vibration to be assessed from the shaft deflection amplitude measured at the mind-span...
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Combined thrust radial bearing of a submarine main shaft – Design and analysis of failure
PublicationThis paper presents an analysis of the combined thrust radial bearing of a submarine propulsion shaft. The lubrication system of the bearing is based on a fixed ring. The efficiency of the lubrication system depends on the shaft speed and temperature, which affects oil viscosity. In turn, the thrust bearing load also depends on the rotational speed of the shaft, because as the speed increases, the drag of the ship increases simultaneously,...
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Multistage Coupling of Eight Mistuned Bladed Discs on Solid Shaft with 1% Mistuning
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Optimisation of turbine shaft heating process under steam turbine run-up conditions
PublicationAn important operational task for thermal turbines during run-up and run-down is to keep the stresses in the structural elements at a right level. This applies not only to their instantaneous values, but also to the impact of them on the engine lifetime. The turbine shaft is a particularly important element. The distribution of stresses depends on geometric characteristics of the shaft and its specific locations. This means a groove manufactured...
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Board cross-section errors while sawing on twin shaft multi-rip saws
PublicationW pracy przedstawiono wpływ warunków pracy pił na powstawanie błędów przecinania w postaci uskoku na przekroju poprzecznym tarcicy.
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Influence of Bearing Bush Geometry on Properties of Water Lubricated Marine Main Shaft Bearings
PublicationW pracy przedstawiono wpływ geometrii smarowanego wodą, okrętowego łożyska ślizgowego wału głównego na jego własności hydrodynamiczne.Wykazano, że wielkość luzu łożyskowego, położenie oraz liczba rowków smarnych mają znaczący wpływ na nośnosć łożyska.
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The concept of estimation of elevator shaft control measurement results in the local 3D coordinate system.
PublicationGeodetic control measurements play an important part because they provide information about the current state of repair of the construction, which has a direct impact on the safety assessment of its exploitation. Authors in this paper have focused on control measurements of the elevator shaft. The article discusses the problem of determining the deviation of elevator shaft walls from the vertical plane in the local 3D coordinate...
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Numerical estimation of the pile toe and shaft unit resistances during the installation process in sands
PublicationNumerical simulations of a pile jacking were carried out. A Coupled Eulerian–Lagrangian (CEL) formulation was used to treat with large deformation problems. An Abaqus, a commercial Finite Element Method software suit, was used as a computing environment. The Mohr–Coulomb constitutive model was applied and the Coulomb model of friction was used to describe pile-soil interaction. Calculations were made for three different pile diameters....
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Influence of main design parameters of ship propeller shaft water-lubricated bearings on their properties
PublicationW artykule omówiono wpływ głównych parametrów konstrukcyjnych i eksploatacyjnych takich jak wielkość luzu łożyskowego, własności materiału panwi, stanu powierzchni skojarzenia ślizgowego oraz temperatury i zasolenia wody na nośność hydrodynamiczną łożyska okrętowego wału śrubowego smarowanego wodą.
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Influence of bush wear in water lubricated marine stern tube bearings with shaft misalignment
PublicationWater lubricated propeller shaft bearings are frequently employed on modern ships due to their advantages such as durability, simplicity and low price. Specific working conditions on ships cause shaft misalignment which often results in rapid wearing of bush and shaft. Shaft misalignment could be an effect of manufacturing or assembly faults but sometimes it appears due to hull or shaft deformation. The wearing process has influence...
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Multistage Coupling of Eight Mistuned Bladed Disk on a Solid Shaft, Forced Vibration Analysis
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Why is TASK Quarterly a Significant Journal to Publish Your Article? —A Bibliometric Analysis of a Scientific and Technical Journal
PublicationA bibliometric analysis of TASK Quarterly in the years 1997-2021 in terms of various bibliometric indicators was performed to celebrate the 25th anniversary of the publication of the first issue of the journal. The number of publications and citations increased over the mentioned span of years. The leading countries in terms of the greatest number of papers published in TASK Quarterly are Poland, Italy, Germany, Ukraine, USA and...
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Estimating of the rough green target size in lumber manufacturing on the twin shaft multi-rip saws
PublicationW pracy przedstawiono analizę i wyniki badań doświadczalnych dokładności przecinania pryzm ze zmrożonego drewna brzozowego na dwuwrzecionowej pilarce tarczowej w warunkach przemysłowych. W badaniach wykorzystywano piły typu "Multix" oraz piły nowego typu. Ponadto, wykazano, że obecność w przekroju poprzecznym, zmiennego na długości przecinanej deski, stopnia po obu jej stronach ma znaczny wpływ na szacowanie wymiaru początkowego...
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Marine propeller shaft bearings under low-speed conditions: water vs. oil lubrication
PublicationThe bearings used in shipbuilding, hydropower, and water pumps have undergone a metamorphosis in recent decades. Because of environmental regulations, lubrication with grease or mineral oil is prohibited. Thus, the standard solutions include water-lubricated bearings with polymer bushings or sealed systems lubricated with oil. When properly designed, assembled, and operated, bearings can operate reliably for years. However, specific...
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WATER LUBRICATED MAIN SHAFT BEARINGS - MODERN SOLUTION FOR HYDROPOWER INDUSTRY - Experimental and theoretical studies
PublicationWater-lubricated bearings are finding increasingly wide use in various branches of industry. As such, they may also be encountered in hydro power industry. They are also increasingly frequently employed in bearing systems of marine shaft propulsions and water pumps [1]. This rising popularity is due to a number of reasons [2]. First of all, their simple construction has direct impact on the level of pricing which is usually quite...
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Shaft Misalignment Influence on Water Lubricated Turbine Sliding Bearings with Various Bush Modules of Elasticity
PublicationW artykule przeanalizowano wpływ wielkości przenoszenia osi wału względem panwi na nośność łożyska. Analizie poddano łożyska z odmiennymi rodzajami panwi o różnej sztywności.
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Assessment of possible application of water lubricated sintered brass slide bearing for marine propeller shaft
PublicationW artykule przedstawiono wyniki badań eksperymentalnych smarowanego wodą łożyska poprzecznego z panwią wykonaną ze spieku brązu.Przedstawiono wyniki pomiarów rozkładu ciśnienia w filmie smarnym, trajektorie osi wału oraz oporów ruchu.Przeprowadzono ocenę przydatności tego typu łożyska do łożyskowania okrętowych wałów śrubowych.
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Fatigue investigation of plain journal bearings
PublicationW artykule przedstawiono wybrane wyniki badań nad wytrzymałością zmęczeniową warstw ślizgowych w panwiach łozysk poprzecznych, prowadzonych w laboratorium tribologicznym Katedry Konstrukcji i Eksploatacji Maszyn Politechniki Gdańskiej. Opisano stanowiska badawcze i metodykę planowania eksperymentów oraz procedurę opracowywania wyników testów zmęczeniowych. Przedstawiono zamierzenia badawcze w zakresie przedmiotowych badań zmęczeniowych.
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ENERGY ANALYSIS OF THE PROPULSION SHAFT FATIGUE PROCESS IN A ROTATING MECHANICAL SYSTEM PART III DIMENSIONAL ANALYSIS
PublicationThis article presents the third and last part of the problem of diagnosing the fatigue of marine propulsion shafts in terms of energy with the use of the action function, undertaken by the authors. Even the most perfect physical models of real objects, observed under laboratory conditions and developed based on the results of their research, cannot be useful in diagnostics without properly transferring the obtained results to the...
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WATER LUBRICATED MAIN SHAFT BEAR INGS WITH THREE LAYER BUSH – MODERN SOLUTION FOR MARINE INDUSTRY
PublicationWater lubricated sliding bearings are increasingly popular in marine and hydro power industry. Such popularity is partly due to their simple construction which also means a relatively affordable price. Properly designed and installed water lubricated bearings may well last for over a decade. During the last decade their traditional range has been expanded with new, modern products like three layer bearing bush. The work presents...
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Multistage Coupling of Eight Mistuned Bladed Disk on a Solid Shaft, Part 1 Free Vibration Analysis
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Multistage Coupling of Eight Mistuned Bladed Discs on Solid Shaft, in book: Recent Advances in Rotor Dynamic
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Durability and mechanical properties of seashell partially-replaced cement, Journal of Building Engineering 2020-09-03 | Journal article |
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Acoustic journal bearing - A search for adequate configuration
PublicationClassical non-contact bearings are already used in a number of specialist applications but there are somespecialist areas where they cannot be used for variety of reasons and acoustic sliding bearings could be an alternative. The paper presents the quest for a configuration of an acoustic journal bearing and shows that the overall shape of the bearing and its geometry are of a vital importance for the load capacity oft he bearing....
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Hyperfine structure and isotope shift study in singly ionized lead
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Lower Temperature Dehydrogenation of Methylcyclohexane by Membrane-assisted Equilibrium Shift
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MEAN SHIFT BASED SEGMENTATION FOR BLEEDING REGIONS IN ENDOSCOPIC VIDEOS
PublicationWith a set of 38 manually marked bleeding regions form endoscopic videos, the authors attempted to find an optimal image segmentation method for reproducing doctor’s markup. Mean shift segmentation combined with HSV histogram segmentation were used as a segmentation method, which was then optimized by tuning the parameters of the method using global optimization algorithm. A target function for measuring the quality of segmentation was...
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Prediction of Pile Shaft Capacity in Tension Based on Some Direct CPT Methods—Vistula Marshland Test Site
PublicationThis paper presents different CPT methodologies for the prediction of the pile shaft resistance in tension on the example of three reference screw piles of the Jazowa test site in Poland. The shaft capacity was estimated based on the cone resistance, sleeve friction and CPT excess pore water pressure. Three piles with diameter 0.4 m and the length varied from 8 m to 14.6 m were subjected to static load tests in tension. Their...
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Some Aspects of Shear Behavior of Soft Soil–Concrete Interfaces and Its Consequences in Pile Shaft Friction Modeling
PublicationThis paper examines the stiffness degradation and interface failure load on soft soil–concrete interface. The friction behavior and its variability is investigated. The direct shear tests under constant normal load were used to establish parameters to hyperbolic interface model which provided a good approximation of the data from instrumented piles. Four instrumented piles were used to obtain reference soil–concrete interface behavior....
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Diagnostics of the drive shaft bearing based on vibrations in the high-frequency range as a part of the vehicle's self-diagnostic system
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Prediction of pile shaft capacity in tension based on some direct CPT methods – Vistula Marshland test site
PublicationThis paper presents different CPT methodologies for the prediction of the pile shaft resistance in tension on the example of three reference screw piles of the Jazowa test site in Poland. The shaft capacity was estimated based on the cone resistance, sleeve friction and CPT excess pore water pressure. Three piles with a diameter of 0.4 m and the length...
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ATTEMPT AT EVALUATING THE INFLUENCE OF BENDING STRESS ON SHAFT WEAR PROCESSES IN WATER LUBRICATED SLIDING BEARING WITH A RUBBER BUSHING
PublicationWater lubricated bearings find increasingly wide application in shipbuilding or hydro–power industry, the popularity stemming from their numerous advantages. Unfortunately, as it turns out, water lubricated bearings do not always meet expectations, as on occasion they become subject to intense, premature wear which requires costly repair. One of the still unexplained phenomena is the process of excessive bearing wear, in particular...
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Search for the most useful geometry of an acoustic journal bearing
PublicationComputer simulations of a number of journal bearing’s geometries utilising acoustic levitation were carried out. The choice of the best geometry depended on the ability of a deformed shape, created by piezo-electric elements, to facilitate squeeze film ultrasonic levitation, and also to create three evenly distributed diverging aerodynamic gaps. Deformations of analysed variants of the bearing’s shape were generated by numerical...
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Hydrodynamic journal bearing - ''Y'' particularly for steam turbines.
PublicationW artykule przedstawiono koncepcję i zasadę działania nowego, ślizgoweo łożyska poprzecznego typu ''Y''. Przedstawiono wady i zalety nowego rozwiązania. Porównano charakterystyki dynamiczne i statyczne klasycznego łożyska cytrynowego (soczewkowego) z nowym łożyskiem ''Y''.Podano przykładowe wdrożenia i ich efekty.
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Operation of slide journal bearings in unsteady energetic description.
PublicationW artykule zaproponowano interpretację wartościującą działania, które (podobnie jak przedstawione mechanice klasycznej działania Hamiltona i Maupertiusa oraz działanie wynikające ze zmiany pędu ciała) jest rozpatrywane jako wielkość fizyczna o jednostce miary zwanej dżulosekundą [dżulsekunda]. Przedstawiono propozycję ilościowej interpretacji działania dowolnego poprzecznego łożyska ślizgowego, w którym zachodzą oddziaływania energetyczne...
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INVESTIGATION OF JOURNAL SLIDE BEARINGS UNDER THE ANGLE OF THEIR FUNCTIONING
PublicationPaper presents the structure and principle of operation of a stand for measurements of influence of the lubrication method and process on functioning of journal slide bearings in their various technical states. Measurements performed on the stand make it possible to take advantage of the new method of evaluating the influence of physical and chemical properties of lubricating oil on the coefficient of friction in the mixed friction...
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Closer Look at the Uncertainty Estimation in Semantic Segmentation under Distributional Shift
PublicationWhile recent computer vision algorithms achieve impressive performance on many benchmarks, they lack robustness - presented with an image from a different distribution, (e.g. weather or lighting conditions not considered during training), they may produce an erroneous prediction. Therefore, it is desired that such a model will be able to reliably predict its confidence measure. In this work, uncertainty estimation for the task...
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Surface Texture Analysis of Hardened Shafts after Ceramic Ball Burnishing
PublicationThis article represents the results of testing the surface condition of shafts manufactured by the burnishing process. The shafts with a hardness of approximately 62 HRC (Rockwell C). were burnished with a ceramic ball (Si3N4), where the force range was controlled by the means of a hydraulic system. The machining process consisted of hard turning shafts with cubic boron nitride (CBN) inserts, followed by burnishing with the use...
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Migration time shift of analytes in micellar electrokinetic chromatography induced by stacking
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Energy shift of the Lβ2 line as an ionization diagnostic for the dense plasma in the PFRP
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Underwater Navigation Ssystem Based on Doppler Shift – Measurements and Error Estimations
PublicationA new acoustic navigation system was developed to determine the position and speed of moving underwater objects such as divers and underwater vehicles. The path of an object and its speed were determined by the Doppler shifts of acoustic signals emitted by a transmitter placed on the object and received by four hydrophones installed at the periphery of the monitored body of water. The position and speed measurements were affected...
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Online Interactivity – Shift Towards E-textbook-based Medical Education
PublicationTextbooks have played the leading role in academic education for centuries and their form has evolved, adapting to the needs of students, teachers and technological possibilities. Advances in technology have caused educators to look for new sources of knowledge development, which students could use inside and outside the classroom. Today’s sophisticated learning tools range from virtual environments to interactive multimedia resources,...
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Failure analysis of a high-speed induction machine driven by a SiC-inverter and operating on a common shaft with a high-speed generator
PublicationDue to ongoing research work, a prototype test rig for testing high-speed motors/generators has been developed. Its design is quite unique as the two high- speed machines share a single shaft with no support bearings between them. A very high maximum operating speed, up to 80,000 rpm, was required. Because of the need to minimise vibration during operation at very high rotational speeds, rolling bearings were used. To eliminate...
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Screw displacement pile shaft deformations measured by vibrating wire and fiber optic systems during a static load test
PublicationThis paper describes a full scale static load test performed on a 400 mm diameter screw displacement pile equipped with four different strain measuring systems. Three types of vibrating wire strain gauges (VWSG) were used: global - retrievable, local attached to steel pipe and local concrete embedded. The fourth system was distributed fiber optic sensors based on Rayleigh back scattering (DFOS) - three in the pile cross section....
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Mathematical Modelling of Drive System with an Elastic Coupling Based on Formal Analogy between the Transmission Shaft and the Electric Transmission Line
PublicationIn the paper, the kinematic structure of the transmission shaft between the driving motor and the working mechanism is studied. The analysis is based on electrical and mechanical similarities. The equivalent circuits, typical for electrical systems, are defined for the transmission shaft concerned. Modelling of the transmission shaft based on a formal analogy between the transmission shaft and the electric transmission line is...
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EVALUATING THE INFLUENCE OF BENDING STRESS ON A 1H18N9 STEEL SHAFT WEAR PROCESS IN A WATER LUBRICATED SLIDING BEARING WITH A RUBBER BUSHING
PublicationThe issue of excessive wear of shaft journals co-working with a rubber bearing has been unexplained so far. Premature and sometimes very intensive wear of ship sliding bearings in water conditions is the reason for carry out very expensive and more frequent than expected repairs. The authors (E. Piątkowska, W. Litwin) made an attempt to find a case that influences the value of this wear described in the paper “Attempt at Evaluating...
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First tests of water lubricated propeller shaft bearings = Wstępne badania zespołu smarowanych wodą łożysk okrętowego wału śrubowego
PublicationW pierwszej części referatu zaprezentowano nowe stanowsko badawcze przy pomocy którego można badać smarowane wodą łożyska wału śrubowego. W drugiej części pracy przedstawiono uzyskane wyniki pomiarów oporów ruchu i trajektorii osi wału.
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The influence of the shift work system on dietary factors contributing to the development of cardiovascular diseases
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Experimental research on effectiveness of the magnetic fluid seals for rotary shafts working in water
PublicationUszczelnianie wałów obrotowych, łożysk i innych zespołów mechanicznych, za pomocą cieczy magnetycznej, tworzącej przegrodę uszczelniającą utrzymywaną siłami pola magnetycznego jest techniką uszczelniania, stosowaną z powodzeniem w urządzeniach pracujących w środowisku gazowym przy ciśnieniu do około 1,0 MPa. Uszczelnienia te umożliwiają również skuteczne rozwiązywanie problemu szczelności przepustów stałych i ruchowych w urządzeniach...
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Quality 5.0: A Paradigm Shift Towards Proactive Quality Control in Industry 5.0
PublicationIndustry 5.0, the latest wave of industrial revolution, is redefining the traditional manufacturing and production landscapes by leveraging advanced technologies, promoting sustainability, and fostering a human-centric approach. An inevitable consequence of this progression is Quality 5.0, the next phase of quality control and assurance. Quality 5.0 aims to transcend the limitations of conventional quality control techniques, which...
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Analysing the potential for application of the phase shift method in endoscopic examination of marine engines
PublicationThe article presents theoretical principles of image processing in digital endoscopy which makes use of a miniaturised spectral scanner “PhaseProbe” designed by General Inspection Technologies LP, the producer of the measuring videoendoscope Everest XLG3. The technology of optoelectronic 3D mapping of the examined surface, which consists in measuring the phase shift between the emitted and reflected light waves, is briefly described....
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NEW DESIGNS OF CENTRIFUGAL MAGNETIC FLUID SEALS FOR ROTATING SHAFTS IN MARINE TECHNOLOGY
PublicationThe centrifugal magnetic fluid seals have important advantage over the conventional centrifugal seals. They maintain very good sealing capacity at static, medium and high speeds of shaft rotation, with the increased seal lifetime, and minimum torque and static friction. These seals are particularly useful in cases when the angular shaft velocity varies and sometimes decreases to nearly or exactly zero, such as in flywheel applications,...
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Experimental investigation into surface texture effect on journal bearings performance
PublicationThe aim of this study was to analyse the performance of journal bearings with specially created dimples on the sliding surface and operating under various conditions. The texture was created on the bearing surface that co-acted with the smooth journal; moreover, the variation of the textured surface of the journal mating with the smooth bearing was tested, and the results were compared to those obtained with the standard smooth...
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Selected problems of experimental investigation of dynamically loaded journal bearings
PublicationIn 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...
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RESEARCH ON HYDRODYNAMIC PEEK JOURNAL BEARINGS LUBRICATED WITH WATER AND OIL
PublicationThe main purpose of the research was to determine the possibilities and experimentally test the benefits of replacing conventional oil lubrication with ecological water lubrication. Tests were carried out on a test rig for hydrodynamic radial bearings under conditions representative of the expected applications for the bearing in water turbines. Bearings made from the polymer material PEEK (polyether ether ketone) were tested under static...
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Running performance of an aerodynamic journal bearing with squeeze film effect
PublicationResults of theoretical and experimental studies concerning the performance of an aerodynamic journal bearing of which running is assisted by squeeze film ultrasonic levitation (SFUL) are presented in this paper. The SFUL mechanism not only can separate journal from the bearing at the start and stop phases of operation but also can significantly contribute to the dynamic stability of the bearing when it runs at speed. Computer calculations...
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Measurement file of stainless stell shaft LSS1 and LSS2 with diameter 95,995 with 3d measurment device
Open Research Data3d point cloud consist of measured points on new stainless steel shaft used during testing hydrodynamic journal PEEK bearing.
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THE INFLUENCE OF HOUSING ARRANGEMENT AND INTERFERENCE ON PRELOAD AND THEORETICAL LIFETIME OF A SYSTEM OF TAPER ROLLER BEARINGS OF A HIGH SPEED SHAFT OF A WIND TURBINE GEARBOX
PublicationA system of two taper roller bearings can carry loads with a high ratio of axial load to radial load. Such a system was proposed for a wind turbine gearbox following the poor durability of original bearing design with the aim of increasing durability. Because of size limits, a proposed system is composed of two different taper roller bearings. Standard manufacturers’ catalogues do not provide information on recommended preload...
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Exploring the meaning of night shift placement in nursing education: A European multicentre qualitative study
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Across-shift changes in upper airways after exposure to bacterial cell wall components
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Water-lubricated bearings of ship propeller shafts - problems, experimental tests and theoretical investigations
PublicationW pracy przedstawiono problemy związane z projektowaniem, montażem i ekspolatcją smarowanych wodą łożysk okrętowych wałów głównych.Przedstawiono wyniki prowadzonych prac badawczych ekperymntalnych i obliczeń.
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A Parallax Shift Effect Correction Based on Cloud Height for Geostationary Satellites and Radar Observations
PublicationThe effect of cloud parallax shift occurs in satellite imaging, particularly for high angles of satellite observations. This study demonstrates new methods of parallax effect correction for clouds observed by geostationary satellites. The analytical method that could be found in literature, namely the Vicente et al./Koenig method, is presented at the beginning. It approximates a cloud position using an ellipsoid with semi-axes...
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Zero phase shift digital filtering for assessment of exposure to non-sinusoidal magnetic fields
PublicationAccuracy of assessment of human body exposure to magnetic fields is affected by several uncertainty sources. One of them is estimation of the total exposure to non-sinusoidal fields. Standard methods can be implemented using analogue or digital filters that introduce a phase shift that affect the result of total exposure level estimation. The paper presents a new method that allows performing more precise assessment of exposure...
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An Approach for Journal Summarization Using Clustering Based Micro-Summary Generation
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Stochastic model for turbulent lubrication of slide journal bearing in ship technology.
PublicationTurbulentny przepływ smarujący ma zastosowanie w obliczeniach praktycznych siły nośnej poprzecznego łożyska ślizgowego dla wysokich prędkości obrotowych przy liczbach Taylora przekraczających wartość 41,2 względnie przy zmodyfikowanych liczbach Reynoldsa o wartościach Re[psi]=2. Główne wyniki pracy koncentrują się na wykazaniu zmian wartości ciśnienia i siły nośnej poprzecznego łożyska ślizgowego w przypadku turbulentnego, izotemicznego...
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Investigation of the IC engine lubricating oil effects on journal bearing life
PublicationPrzedstawiono wyniki modelowych badań eksperymentalnych wytrzymałości zmęczeniowej warstwy ślizgowej łożysk silników spalinowych. W szczególności oceniono wpływ właściwości oleju smarowego na tę wytrzymałość.
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Water-Lubricated Sintered Bronze Journal Bearings—Theoretical and Experimental Research
PublicationWater lubricated bearings are used from many years in shipbuilding, hydro power and other industries because of their advantages such as: extensive serviceable life, low coefficient of friction, longevity of shaft sleeve, good abrasion resistance, low maintenance required, unit simplicity, no danger of pollution and low price. Various types of water lubricated sliding bearings have been tested at the Technical University of Gdansk...
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Investigation of the thermal effects in water-lubricated journal bearings with axial grooves
PublicationWater-lubricated hydrodynamic journal bearings are frequently applied as stern tube bearings due to their advantages over other bearing types. They are environmentally friendly, can operate without sealings and in conditions of low friction losses. The most popular are bearings with open axial grooves, which require, for proper operation, forced axial flow of the lubricating water. Correctly designed and operated stern tube bearings...
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Problems of analytical determination of journal bearing bush fatigue strength estimates
PublicationProblems connected with determination of stress distribution in sliding layer of thinwalled bearing bushes, investigated in bearing fatigue test rigs, have been presented. Using an example of plain bearings tested in the fatigue machine SMOK (built at the Gdask University of Technology) problems with obtaining a convergence of iterative procedure for determining the fatigue strength estimators of bearing alloy surface layer are...
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Experimental study of the fuel jet combustion in high temperature and low oxygen content exhaust gases
PublicationPrzeprowadzono badania eksperymentalne spalania pojedynczego strumienia paliwa gazowego. Paliwo podawano współosiowo do generowanych przez konwencjonalny palnik gazowy spalin o wysokiej temperaturze i niskiej zawartości tlenu. Badano wpływ zawartości tlenu w utleniaczu na widzialność płomienia i skład produktów spalania.
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Temperature distribution in laser-clad multi-layers
PublicationW pracy przedstawiono porownanie rezultatów numerycznej symulacji rozkładu temperatur w warstwach nakładanych laserowo z wynikami pomiarów doświadczalnych. Otrzymano bardzo dobrą zgodność wyników co pozwala wnioskować, że przedstawiony model numeryczny może służyć jako efektywne narzędzie wstępnego doboru parametrów procesu laserowego nakładania warstw.
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Wojciech Litwin dr hab. inż.
People1992÷1996 - study on Mechanical Department at Gdansk University of Technology1996 – employed in the Faculty of Ocean Engineering and Ship Technology at the Gdansk University of Technology2004 – PhD2014 – habilitation2016 - vice dean for science at Faculty of Ocean EngineeringHe participated in a number of designing and research programs connected with water lubricated bearings, solar technology and modern ship propulsion. Since...
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Isotope shift study in two visible lines: 500.6 nm and 520.3 nm of Pb I
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Mean Shift Segmentation Assessment for Individual Forest Tree Delineation from Airborne Lidar Data
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The effect of an active force while slide diamond burnishing of wooden shafts upon process quality
PublicationThe quality of the surface of wooden elements that have been turned and burnished has got a crucial meaning in the whole production process flow, since the obtained effects affect the quality of the wooden surface after finishing (coating, painting). In the paper, selected results of the investigation of the effect of the burnishing process on the surface quality of the elements after turning are presented. Research experiments...
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An extended basis inexact shift–invert Lanczos for the efficient solution of large-scale generalized eigenproblems
PublicationThis paper proposes a technique, based on the Inexact Shift–Invert Lanczos (ISIL) method with Inexact Jacobi Orthogonal Component Correction (IJOCC) refinement, and a preconditioned conjugate-gradient (PCG) linear solver with multilevel preconditioner, for finding several eigenvalues for generalized symmetric eigenproblems. Several eigenvalues are found by constructing (with the ISIL process) an extended projection basis. Presented...
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PHYSICAL MODEL OF ENERGY-RELATED PROCESSES IN A ROTATING MECHANICAL SYSTEM FOR THE PURPOSES OF DIAGNOSIS OF TRANSMISSION SHAFTS
PublicationIn the present article, selected problems connected with identification of slowly changing energy-related processes accompanying high cyclic fatigue of construction materials of simple mechanical systems, with special consideration of transmission shafts, are mentioned for diagnostic purposes. The article also presents physical models of object and processes that in a simplified way reflect mechanical energy transmission from transmission...
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A comparative performance assessment of a hydrodynamic journal bearing lubricated with oil and magnetorheological fluid
PublicationThis work presents the investigation results of a journal bearing lubricated with magnetorheological fluid that is activated by a local constant magnetic field to vary both the local flow resistance and pressure. The bearing performance is assessed via Finite Element Modelling (FEM) and results are corroborated by experiments. The FEM model uses the Bingham model to describe the fluid film. A dedicated test rig is used to assess...
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Water-Lubricated Journal Bearings Marine Applications, Design, and Operational Problems and Solutions
PublicationWater-Lubricated Journal Bearings: Marine Applications, Design, and Operational Problems and Solutions provides cutting-edge design solutions, common problems and methods for avoiding them, and material selection considerations for the use of water-lubricated journal bearings in marine environments. These bearings have many advantages, including the absence of the potential for oil contamination. They are also sensitive, and their...
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Research on heavy loaded water lubricated main shaft bearings of the ship = Badania mocno obciążonych, smarowanych wodą łożysk wału śrubowego jednostki pływającej
PublicationW referacie zaprezentowano wyniki badań łożyska z polimerową panwią smarowanego wodą, jednego z wiodących producentów. Próby prowadzono dla dwóch odmiennych warunków pracy: dla typowych wielkości obciążeń, jakie występują w łożysku rufowym okrętowego wału głównego oraz dla obciążeń, przy których średnie naciski są bliskie wartościom dopuszczalnym, określonym przez producenta. Przeprowadzone badania wykazały, że łożysko pracuje...
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Research on water lubricated main shaft bearings in conditions of improper lubrication and cooling conducted on high torque real-life scale bush test rig
PublicationWater lubricated polymer bushes find increasingly popular use in the sliding bearings of marine propellers, water turbines and pump shafts. Such popularity is partly due to their simple construction which also means relatively affordable price. In addition, properly designed and installed water lubricated bearings may well last for over a decade. However, in practical experience one may also observe cases of rapid wear...
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Across-Shift Changes in Viable Nasal Bacteria among Waste-Incineration Plant Workers—A Pilot Study
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