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Wyniki wyszukiwania dla: bar/diaphragm bracing,trapezoidal cladding,imperfection force,steel structures,truss girder
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Study of particle - bubble interaction using atomic force microscopy - current possibilities and challenges
PublikacjaBadania oddziaływań pomiędzy cząstkami mineralnymi i pęcherzykami powietrza są kluczowe do zrozumienia przebiegu flotacji. Wykorzystanie mikroskopii sił atomowych (AFM) i techniki próbnika koloidalnego umożliwia pomiar takich oddziaływań.
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Experimental determination of impact stiffness parameters for the non-linear viscoelastic model of pounding force
PublikacjaNieliniowy model lepko-sprężysty umożliwia dokładną symulację siły zderzenia w czasie oraz symulację odpowiedzi konstrukcji podatnej na zderzanie podczas trzęsień ziemi. Celem tego artykułu jest eksperymentalne wyznaczenie wartości współczynnika sztywności zderzenia jako parametru tegoż modelu.
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Chained machine learning model for predicting load capacity and ductility of steel fiber–reinforced concrete beams
PublikacjaOne of the main issues associated with steel fiber–reinforced concrete (SFRC) beams is the ability to anticipate their flexural response. With a comprehensive grid search, several stacked models (i.e., chained, parallel) consisting of various machine learning (ML) algorithms and artificial neural networks (ANNs) were developed to predict the flexural response of SFRC beams. The flexural performance of SFRC beams under bending was...
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Effect of Some Sulphur Additives on The Degradation of 9Cr-1Mo Steel After Its 10 Years Service in The CCR Platforming Unit
PublikacjaThe work shows the results of the tests of 9Cr-1Mo steel, which was for 10 years operated in the CCR platforming unit in Group Lotos SA in Gdańsk, and then in the laboratory was sulphidised during 166 h at a temperature of 600 °C. Sulphidation was performed in a mixture of H2-H2S gases at the vapour pressure of sulphur 4.1·10-14 atm, so the order of magnitude of vapour pressure was less than that of the dissociation pressure of...
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Multivariate analysis of impedance data obtained for coating systems of varying thickness applied on steel
PublikacjaElectrochemical impedance spectroscopy (EIS) has proven to be a valuable test method for the electrochemical characterization of protective coatings on metals. The common way of analysis in impedance spectroscopy is to model the impedance spectrum by means of an equivalent circuit and to extract the quantity of interest using optimization techniques. A model, corresponding to the behavior of the sample under testing, is important...
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The effect of pre-hydrogen charging on corrosion behaviour of superduplex stainless steel welded joints
PublikacjaThe paper presents results of research undertaken to determine the influence of hydrogen on passivity and corrosion resistance of 2507 super duplex stainless steel welded joints. Butt welded joints were made with low heat input using flux corded arc welding (FCAW) method. Coupons of 5.0 x 5.0 mm were cut from the welded joints containing weld metal (WM), heat affected zone (HAZ) and parent metal (PM). Hydrogen was introduced...
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Experimental investigation of Steel–Concrete–Polymer composite barrier for the ship internal tank construction
PublikacjaTransportation of dangerous cargo by ships demands ensuring an appropriate protection level in case of an accident. Two of the most dangerous accident types resulting in an oil spill are grounding and ship to ship collision. The article presents results of research on a new composite construction for a ship hull that increases structural safety during collision. The concept of semi-elastic Steel–Concrete–Polymer structure is presented....
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Numerical modelling and analysis of steel specimens subjected to marine immersed corrosion and tensile load
PublikacjaThe present study develops numerical models to analyse the behaviour of steel specimens subjected to marine immersed corrosion degradation and tensile load. The finite element method with the use of the explicit dynamic solver LS-DYNA, satisfying the quasi-static conditions, is employed. Two numerical models are developed, where in the first one, the scans of surfaces gathered from corroded plate specimens are implemented directly...
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EM-Driven Multi-Objective Optimization of Antenna Structures in Multi-Dimensional Design Spaces
PublikacjaFeasible multi-objective optimization of antenna structures is presented. An initial set of Pareto optimal solutions is found using a multi-objective evolutionary algorithm (MOEA) working with a fast surrogate antenna model obtained by kriging interpolation of coarse-discretization EM simulation data. To make the surrogate construction computationally feasible in multi-dimensional design space, the space subset containing non-dominated...
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Simplified Map-based Selection of Optimal Spindle Speeds When Milling Complex Structures
PublikacjaIn the paper a method for selecting optimal spindle speeds for complex structures during milling operations is presented. It is based on the selection of the spindle speed in accordance with a simple equation resulting from the minimisation of vibration energy, which leads to the minimisation of the work of cut-ting forces presented in previous elaborations by the authors [1]. Optimal spindle speeds are obtained for many points...
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A new time-frequency detection method of stray current field interferenceon metal structures.
PublikacjaA new detection method has been presented of stray current field interference on underground metal structures. The method employs short time Fourier transformation (STFT). This method of analysis allows determination of signal spectral power density changes (e.g., structure potential) in the function of time. In the paper results have been presented of total time–frequency analysis of a pipeline potential in a stray current field...
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Finite element method simulations of various cases of crash tests with N2/W4/A steel road barrier
PublikacjaThe subject of this study is performance of N2/W4/A steel road safety barrier investigated in numerical simulations. System was checked under several types of initial conditions, which were assumed basing on the TB11 and TB32 normative crash tests. The main goal of present study is to investigate the relationship between initial conditions (angle and velocity) of the impact and the severity indices (associated to the vehicle occupant) during...
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Fragility analysis of structural pounding between adjacent structures arranged in series with various alignment configurations under near‑field earthquakes
PublikacjaA major cause of local to total damages is related to structural pounding in a large number of past earthquakes. In general, these collisions take place as a result of differences in the dynamic characteristics of the colliding structures. To acquire a better perception of the behavior of structures, in this paper, three structures featuring different heights are modeled in series and with various configurations next to each other...
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Straightening of ship hull structure made of 316L stainless steel - tensile test of naturally cooled material
Dane BadawczeThe 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,...
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Straightening of ship hull structure made of 316L stainless steel - tensile test of water cooled materia
Dane BadawczeThe 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,...
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Sub-national structures matter when evaluating physical activity promotion: Lessons from Germany
PublikacjaBackground Public policies are increasingly acknowledged as important part of promoting physical activity (PA). However, especially in states with sub-national administrative structures such as Germany, national and sub-national approaches differ considerably. In Germany, sport for all (SfA) promotion is mostly organized at sub-national level, which is usually not covered in national evaluations. Knowledge of these structures helps...
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Fast multi-objective design optimization of microwave and antenna structures using data-driven surrogates and domain segmentation
PublikacjaPurpose Strategies and algorithms for expedited design optimization of microwave and antenna structures in multi-objective setup are investigated. Design/methodology/approach Formulation of the multi-objective design problem oriented towards execution of the population-based metaheuristic algorithm within the segmented search space is investigated. Described algorithmic framework exploit variable fidelity modeling, physics- and...
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Improved selectivity compact band-stop filter with gosper fractal-shaped defected ground structures
PublikacjaA novel band-stop filter using Gosper fractal-shaped defected ground structures has been designed and manufactured. The improvement in the filter selectivity has been achieved by introducing a multiresonance fractal-shaped defect leading to a higher filter order, simultaneously maintaining its compact size. The experimental results prove the validity of proposed solution and its utility in novel miniaturized and severe requirement...
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Karol Niklas dr inż.
OsobyKarol NIKLAS jest adiunktem w Wydziale Inżynierii Mechanicznej i Okrętownictwa Politechniki Gdańskiej . Pracę dyplomową magisterską na kierunku "Budowy okrętów morskich" w specjalności "Budowa małych statków i jachtów" obronił w 2007 roku. W 2008 roku ukończył studia podyplomowe w specjalności "Nowoczesne Metody Symulacyjne w Technice" na Wydziale Fizyki i Matematyki Stosowanej. W 2014 roku obronił rozprawę doktorską pt. "Zastosowanie...
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TEM, EDS and optical microscope images of pristine and silica-coated bismuth oxide (Bi2O3) and gadolinium oxide (Gd2O3) structures.
Dane BadawczeData consists of raw TEM/EDS and optical microscope images of pristine and silica-coated bismuth oxide (Bi2O3) and gadolinium oxide (Gd2O3) structures. Additional TEM images and optical microscope images of silica shells were included.
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Influence of plastic deformation on stray magnetic field distribution of soft magnetic steel sample
PublikacjaThe effect of various combinations of conditions, i.e., presence of the Earth’s magnetic field during and after deformation on the distribution of stray magnetic field of S355 steel sample, which is locally deformed, was investigated. Some of the stages of the experiment were carried out in zero magnetic field. Compensation of the Earth’s magnetic field was obtained by the application of a pair of Helmholtz coils. These coils are...
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The effect of external load on ultrasonic wave attenuation in steel bars under bending stresses
PublikacjaThe stress state in deformed solids has a significant impact on the attenuation of an ultrasonic wave propagating through the medium. Measuring a signal with certain attenuation characteristics can therefore provide useful diagnostic information about the stress state in the structure. In this work, basic principles behind a novel attenuation-based diagnostic framework are introduced. An experimental study on steel bars under three-point...
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Closer look into the structures of tetrabutylammonium bromide–glycerol-based deep eutectic solvents and their mixtures with water
PublikacjaIn recent years, deep eutectic solvents (DES) and it’s mixture with water have become more and more attention as green solvents used in chemistry. However, there are only a few theoretical studies on the mechanisms of pure DES and DES-water complex formation. Therefore, the structural properties of tetrabutylammonium bromide–glycerol-based deep eutectic solvents and their mixtures with water have been investigated by means of Molecular...
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Non-Linear Analysis of Structures Utilizing Load-Discretization of Stiffness Matrix Method with Coordinate Update
PublikacjaThis paper proposes a stiffness method based structural analysis algorithm for geometrically non-linear structures. In this study, the applied load on the joints has been discretized to a sequence of a few loadings applied. Each loading step produces incremental external nodal displacements, which are added to the corresponding coordinates to get a new geometrical shape of the structure. This process is iteratively repeated until...
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Image-based numerical modeling of the tensile deformation behavior and mechanical properties of additive manufactured Ti–6Al–4V diamond lattice structures
PublikacjaThis work concerns the numerical modeling of the deformation process and mechanical properties of structures obtained by the additive method laser power bed fusion (LPBF). The investigation uses diamond structures of Ti–6Al–4V titanium implantation alloy with various relative densities. To model the process of tensile deformation of the materials, geometric models were used, mapping the realistic shape of the examined structures....
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On Improved-Reliability Design Optimization of High-Frequency Structures Using Local Search Algorithms
PublikacjaThe role of numerical optimization has been continuously growing in the design of high-frequency structures, including microwave and antenna components. At the same time, accurate evaluation of electrical characteristics necessitates full-wave electromagnetic (EM) analysis, which is CPU intensive, especially for complex systems. As rigorous optimization routines involve repetitive EM simulations, the associated cost may be significant....
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Detekcja uszkodzeń w kratownicy kompozytowej z zastosowaniem fal giętno-scinających.Damage detection in composite truss by application coupled flexural - shearwaves.
PublikacjaW pracy przedstawiono zastosowanie fal spręzystych do detekcji peknięć w kratownicy kompozytowej.
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Investigating the Effects of Geometrical Parameters of Re-Entrant Cells of Aluminum 7075-T651 Auxetic Structures on Fatigue Life
PublikacjaIn this study, the effects of two geometrical parameters of the re-entrant auxetic cells, namely, internal cell angle (θ) and H/L ratio in which H is the cell height, and L is the cell length, have been studied on the variations of Poisson’s ratio and fatigue life of Aluminum 7075-T6 auxetic structures. Five different values of both the H/L ratio and angle θ were selected. Numerical simulations and fatigue life predictions have...
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Instantaneous Impedance Analysis of Non-Stationary Corrosion Process: a Case Study of Carbon Steel in 1M HCl
PublikacjaThe paper concerns the problem of evaluation of stationarity of carbon steel corrosion in 1M HCl. Comparison of corrosion rate with addition of corrosion inhibitor to the reference measurement is the most often used way of evaluating inhibitor efficiency. Such an approach is valid only if corrosion rate is a stationary process. Two complementary techniques were used simultaneously: volumetric analysis of evolved hydrogen and instantaneous...
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Wybrane aspekty modelowania uderzenia pojazdem dźwigara wiaduktu
PublikacjaW pracy przedstawiono różne zagadnienia związane z uderzeniem pojazdu w dźwigar wiaduktu. Omówiono wybór modelu obliczeniowego, na podstawie porównania wyników dla modelu dźwigara zespolonego, modelu dźwigara stalowego oraz modelu wiaduktu. Następnie opisano model dźwigara zespolonego zastosowany w analizie MES oraz metodę wyznaczania współczynników tłumienia Rayleigha. Symulację numeryczną uderzenia dźwigara wiaduktu przez koparkę...
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Shaking table experimental study on the effectiveness of polymer bearings for seismic isolation of structures
PublikacjaSeismic isolation has been recognised to be a very effective way of protecting structures from damage during earthquakes. It allows us to extend the natural period of the structure and therefore avoid resonance with the ground motion. Moreover, by increasing damping in the isolation devices, more energy can be dissipated and thus the structural response can be further reduced. The aim of this paper is to show the results of the...
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Kriging metamodels and design re‐utilization for fast parameter tuning of antenna structures
PublikacjaThe paper addresses the problem of computationally efficient electromagnetic (EM)‐driven design closure of antenna structures. The foundations of the presented approach are fast kriging interpolation metamodels, utilized for two purposes: (a) producing a good starting point for further parameter tuning, and (b) yielding a reasonable Jacobian matrix estimate to jump‐start the optimization procedure. The models are rendered using...
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A higher order transversely deformable shell-type spectral finite element for dynamic analysis of isotropic structures
PublikacjaThis paper deals with certain aspects related to the dynamic behaviour of isotropic shell-like structures analysed by the use of a higher order transversely deformable shell-type spectral finite element newly formulated and the approach known as the Time-domain Spectral Finite Element Method (TD-SFEM). Although recently this spectral approach is reported in the literature as a very powerful numerical tool used to solve various...
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Experimental research on over-laminated steel sandwich panel connection to determine the form of fatigue failure
PublikacjaThe novel means of transport need to meet rising both the economic and ecologic requirements. In recent years the International Maritime Organization (IMO) introduced new measure of ship energy efficiency (the EEDI index), as well as new regulations regarding higher quality of fuel (so called Tier limits). It resulted in much higher interest of the technological development of ships. One of the solution having great potential is...
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Effect of bending-torsion on fracture and fatigue life for 18Ni300 steel specimens produced by SLM
PublikacjaIn this study, different fracture surfaces caused by fatigue failure were generated from 18Ni300 steel produced by selective laser melting (SLM). Hollow round bars with a transverse hole were tested under bending-torsion to investigate the crack initiation mechanisms and fatigue life. Next, the post-failure fracture surfaces were examined by optical profilometer and scanning electron microscope. The focus is placed on the relationship...
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Rapid Yield Estimation and Optimization of Microwave Structures Exploiting Feature-Based Statistical Analysis
PublikacjaIn this paper, we propose a simple, yet reliable methodology to expediteyield estimation and optimization of microwave structures. In our approach,the analysis of the entire response of the structure at hand (e.g., $S$-parameters asa function of frequency) is replaced by response surface modeling of suitablyselected feature points. On the one hand, this is sufficient to determinewhether a design satisfies given performance specifications....
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Theoretical and experimental analysis of guided wave propagation in plate-like structures with sinusoidal thickness variations
PublikacjaGuided waves have attracted significant attention for non-destructive testing (NDT) and structural health monitoring (SHM) due to their ability to travel relatively long distances without significant energy loss combined with their sensitivity to even small defects. Therefore, they are commonly used in damage detection and localization applications. The main idea of incorporating guided waves in NDT and SHM is based on processing...
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Orientation effects on the fracture behaviour of additively manufactured stainless steel 316L subjected to high cyclic fatigue
PublikacjaIn this paper, stainless steel 316L (SS316L) bars were additively manufactured (AM) in three orientations (Z – vertical, XY – horizontal, ZX45 – midway between vertical and horizontal) by using the Laser Powder Bed Fusion Melting (LPBF-M) method. The AM specimens were subjected to load control fatigue testing under full tension and compression (R = -1) at stress amplitudes ±350, ±400 and ±450 MPa. The XY and ZX45 printing orientations...
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"Raport z wstępnych badań własności stali trudnościeralnej 460HB",. ang "Report on preliminary tests of the properties of wear-resistant steel 460HB"
PublikacjaMikrostrukturę badanej stali trudnościeralnej 460HB stanowi drobnoziarnisty martenzyt odpuszczony, który jest właściwy dla stali konstrukcyjnych niskowęglowych, niskostopowych ulepszonych cieplnie. W przypadku blach grubych, do których zalicza się badana stal, struktura może ulec zaburzeniu, jeżeli w hutniczym procesie wytwórczym wystąpiła niejednorodność odkształcenia plastycznego i w konsekwencji tworzenie się pasm segregacyjnych,...
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X-ray diffraction (XRD) of silica-coated bismuth oxide (Bi2O3) and gadolinium oxide (Gd2O3) structures
Dane BadawczeData contain results from X-ray diffraction (XRD) measurements of pristine Bi2O3 and Gd2O3 structures using Aeris diffractometer (Malvern Panalytical, Malvern, UK) with Cu-Kα radiation (λ = 1.544 Å)
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DEFORMATIONS OF INNOVATIVE COLD-FORMED GEB SECTIONS
PublikacjaPermanent urban growth of the world of today world implies demanding challenges for the steel construction industry. Nowadays, one of the most important issues is the cost optimization of steel structures. Since the weight of building materials is a major component of the total cost, engineers and designers try to reduce structural weight, without compromising durability and sustainability of a steel structure. Therefore, light...
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Accurate Modeling of Antenna Structures by Means of Domain Confinement and Pyramidal Deep Neural Networks
PublikacjaThe importance of surrogate modeling techniques has been gradually increasing in the design of antenna structures over the recent years. Perhaps the most important reason is a high cost of full-wave electromagnetic (EM) analysis of antenna systems. Although imperative in ensuring evaluation reliability, it entails considerable computational expenses. These are especially pronounced when carrying out EM-driven design tasks such...
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SEM micrographs of the austenitic stainless steel corrosion in asphalt fumes
Dane BadawczeThe dataset contains the scanning electron microscopy (SEM) studies of the austenitic stainless steels: AISI 304, AISI 316, AISI 321 and duplex stainless steel AISI 2205. The samples were polished and exposed to the installation carrying asphalt fumes at elevated temperatures (approx. ~210-240 Celsius). The exposition duration was three months. Some...
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Novel 1,2,3-Triazole Derivatives as Mimics of Steroidal System—Synthesis, Crystal Structures Determination, Hirshfeld Surfaces Analysis and Molecular Docking
PublikacjaHerein, we present the synthesis and crystal structures determination of five 4-(1-phenyl-1H-1,2,3-triazol-4-yl)phenol derivatives containing halogen atoms, 6a–e, which may be used as an excellent mimic of steroids in the drug development process. Good quality crystals obtained for all of the synthesized compounds allowed the analysis of their molecular structures. Subsequently, the determined crystal structures were used to calculate...
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Mechanical properties of cement pastes containing pristine and silica-coated bismuth oxide (Bi2O3) and gadolinium oxide (Gd2O3) structures
Dane BadawczeExcel file containing raw mechanical (compressive strength) data of cement pastes containing variable amount of Bi2O3, Gd2O3, Bi2O3-SiO2 and Gd2O3-SiO2 structures. Sample designation in the Excel file is in line with sample designation in the manuscript associated with dataset.
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Pitting corrosion in steel and electrochemical noise intensity
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Uniform corrosion monitoring of carbon steel in concrete
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Study on the strength of laminated polyurethane-steel joints
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Grease effect on fretting wear of mild steel
PublikacjaNa stanowisku laboratoryjnym przeprowadzono badania zużycia frettingowego miękkiej stali smarowanej mineralnymi i syntetycznymi smarami zawierającymi także różne dodatki: grafit dwusiarczek molibdenu ZDDP i ditiocarbamat molibdenu, w różnych stężeniach.Badania wykazały istotny wpływ konsystencji smaru i jego właściwości smarnych na zużycie frettingowe miękkiej stali oraz zróżnicowany wpływ testowanych dodatków. Obecność smaru...
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Protective coatings for stainless steel for SOFC applications
PublikacjaW pracy przedstawiono badania związane z warstwami antykorozyjnymi stali nierdzewnych stosowanych w tlenkowych ogniwach paliwowych. Warstwy przygotowana z użyciem prekursorów polimerowych na bazie Y i Co. Użyta stal to Crofer 22 APU.