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Search results for: STRESS OSCILLATIONS
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Modeling of the Two-Dimensional Flow Caused by Sea Conditions and Wind Stresses on the Example of Dead Vistula
PublicationThe article presents the results of two-dimensional modeling of flows caused by the sea conditions and wind stresses on the example of Dead Vistula. Based on the available bathymetric data, a numerical model of the river section was created, which was supplemented with data on the position of the water table depending on hydrometeorological conditions. To describe the flow field in steady conditions, a simplified model of two-dimensional...
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Damage assessment during creep and fatigue of power plant steels using destructive and nondestructive techniques
PublicationOpisano wyniki badń mających na celu ocena uszkodzeń od pełzania i zmęczenia stali energetycznych z wykorzystaniem technik niszczących i nieniszczących
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Wpływ wyżarzania na strefę połączenia blachy Al-Cu zgrzewanej wybuchowo i walcowanej.
PublicationW pracy omówiono wpływ zgniotu, czasu i temperatury wyżarzania walcowanej na zimno blachy platerowanej Al-Cu na jakość połączenia w strefie zgrzewania.
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Dynamika i ewolucja środowiska przyrodniczego strefy nadmorskiej w Polsce - przyczyny, skutki, prognoza.
PublicationW artykule omówiono następujące zagadnienia: istota strefy nadmorskiej;przejawy dynamiki i ewolucji środowiska przyrodniczego; prognoza przemian środowiska przyrodniczego; kształtowanie środowiska przyrodniczego jako czynnik jego przemian.
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Dynamic elektrochemical impedance spectroscopy measurements of passive layer cracking under static tensile stresses.
PublicationDynamiczna elektrochemiczna spektroskopia impedancyjna umożliwia badanie podatności i odporności korozyjnej różnych materiałów konstrukcyjnych, a w szczególności określenie właściwości elektrochemicznych warstw pasywnych występujących na ich powierzchni. W wielu przypadkach pęknięcie warstwy pasywnej pod wpływem działania naprężeń rozciągających prowadzi do korozji naprężeniowej. Z tego względu badania pękania warstw pasywnych...
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Dynamic electrochemical impedance spectroscopy measurements of passive layer cracking under static tensile stresses.
PublicationDynamiczna Elektrochemiczna Spektroskopia Impedancyjna umożliwia badanie podatności i odporności korozyjnej różnych materiałów konstrukcyjnych, a w szczególności określenie właściwości elektrochemicznych warstw pasywnych występujących na ich powierzchni. W wielu przypadkach pęknięcie warstwy pasywnej pod wpływem działania naprężeń rozciągających prowadzi do korozji naprężeniowej. Z tego względu badania pękania warstw pasywnych...
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Pomiary naprężeń w warstwie wierzchniej stali duplex metodą dyfrakcji promieniowania rentgenowskiego g-sin2Ψ = Residual stress measurements in duplex steel surface layers by g-sin2Ψ x-ray diffraction method
PublicationPrzedstawiono wyniki pomiarów naprężeń w warstwie wierzchniej z wykorzystaniem metody dyfrakcji promieniowania rentgenowskiego g-sin2. Wyjaśniono zasady przeprowadzania pomiarów naprężeń na próbkach walcowych o małej średnicy. Badania prowadzono na próbkach okrągłych ze stali duplex, poddanych procesom nagniatania. Stwierdzono występowanie naprężeń ściskających w warstwach powierzchniowych wszystkich badanych próbek oraz istotne...
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Temperature-induced changes of HtrA2(Omi) protease activity and structure
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Failure analysis and modernization of high-pressure hydraulic press for drilling tubes testing
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Optimization of Wastes Compaction Parameters in Case of Gradual Wear of the Briquetting Press Rolls
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DRESS SYNDROME AS SERIOUS SKIN HYPERSENSITIVITY REACTIONS ASSOCIATED WITH OLANZAPINE: CASE REPORT
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A perfect hashing incremental scheme for unranked trees using pseudo-minimal automata
PublicationWe describe a technique that maps unranked trees to arbitrary hash codes using a bottom-up deterministic tree automaton (DTA). In contrast to other hashing techniques based on automata, our procedure builds a pseudo-minimal DTA for this purpose. A pseudo-minimal automaton may be larger than the minimal one accepting the same language but, in turn, it contains proper elements (states or transitions that are unique) for every input...
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Simulation Tests of Working Press Loads under Pre-tensioned Body Conditions
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EIGHT OLD CULTIVARS OF APPLE TREES – AN EVALUATION OF THEIR POTENTIAL FOR USE BY THE PROCESSING INDUSTRY
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Inception and Propagation of Electrical Trees in the Presence of Space Charge in HVAC Extruded Cables
PublicationThis paper presents the space charge impact on the inception and propagation of electrical trees in cross-linked polyethylene (XLPE) insulation via simulations and experimentation. A 3D finite element analysis (FEA)-based modeling is proposed to simulate electrical trees via a needle embedded on the XLPE insulation. The proposed FEA model demonstrates the influence of the space charge magnitude and polarity on the initiation of...
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Geo-Questionnaire for Environmental Planning: The Case of Ecosystem Services Delivered by Trees in Poland
PublicationStudies on society and the environment interface are often based on simple questionnaires that do not allow for an in-depth analysis. Research conducted with geo-questionnaires is an increasingly common method. However, even if data collected via a geo-questionnaire are available, the shared databases provide limited information due to personal data protection. In the article, we present open databases that overcome those limitations....
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Constant-Factor Approximation Algorithm for Binary Search in Trees with Monotonic Query Times
PublicationWe consider a generalization of binary search in linear orders to the domain of weighted trees. The goal is to design an adaptive search strategy whose aim is to locate an unknown target vertex of a given tree. Each query to a vertex v incurs a non-negative cost ω(v) (that can be interpreted as the duration of the query) and returns a feedback that either v is the target or the edge incident to v is given that is on the path towards...
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Reliability assessment of truss towers using Monte Carlo Method, PEM and RSM
PublicationThe paper discusses the reliability assessment of simple random truss structures using three different probabilistic methodologies: the Monte Carlo method, the Point Estimate Method and the Response Surface Method. A benchmark truss structure example is analyzed. A set of numerical calculations of critical load is performed and the results are taken as the basis of advanced probabilistic calculations. Using the samples, numerical...
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Modelling and Measurement of Folk Guitar: Truss Rod and Strings in Numerical Analysis of Tone
PublicationThe study makes an attempt to model a complete vibrating guitar including its non-linear features, specifically the tension-compression of truss rod and tension of strings. The purpose of such a model is to examine the influence of design parameters on tone. Most experimental studies are flawed by uncertainties introduced by materials and assembly of an instrument. Since numerical modelling of instruments allows for deterministic...
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Load carrying capacity of the eccentric joint in the truss made of open cross-sections
PublicationThe influence of eccentricity at intersections of truss members on the load carrying capacity of the truss joint is presented in the paper. The research truss elements were designed as cold-formed open cross section. Analytical calculations, numerical analysis and experimental research were conducted to reveal how the eccentricity affects the effort of material in the joint area. The results of analysis and investigations are compared...
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On trees with double domination number equal to total domination number plus one
PublicationA total dominating set of a graph G is a set D of vertices of G such that every vertex of G has a neighbor in D. A vertex of a graph is said to dominate itself and all of its neighbors. A double dominating set of a graph G is a set D of vertices of G such that every vertex of G is dominated by at least two vertices of D. The total (double, respectively) domination number of a graph G is the minimum cardinality of a total (double,...
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On trees with double domination number equal to 2-domination number plus one
PublicationA vertex of a graph is said to dominate itself and all of its neighbors. A subset D subseteq V(G) is a 2-dominating set of G if every vertex of V(G)D is dominated by at least two vertices of D, while it is a double dominating set of G if every vertex of G is dominated by at least two vertices of D. The 2-domination (double domination, respectively) number of a graph G is the minimum cardinality of a 2-dominating (double dominating,...
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Comparing Arbitrary Unrooted Phylogenetic Trees Using Generalized Matching Split Distance
PublicationIn the paper, we describe a method for comparing arbitrary, not necessary fully resolved, unrooted phylogenetic trees. Proposed method is based on finding a minimum weight matching in bipartite graphs and can be regarded as a generalization of well-known Robinson-Foulds distance. We present some properties and advantages of the new distance. We also investigate some properties of presented distance in a common biological problem...
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Comparing Phylogenetic Trees by Matching Nodes Using the Transfer Distance Between Partitions
PublicationAbility to quantify dissimilarity of different phylogenetic trees describing the relationship between the same group of taxa is required in various types of phylogenetic studies. For example, such metrics are used to assess the quality of phylogeny construction methods, to define optimization criteria in supertree building algorithms, or to find horizontal gene transfer (HGT) events. Among the set of metrics described so far in...
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On the ratio between 2-domination and total outer-independent domination numbers of trees
PublicationA 2-dominating set of a graph G is a set D of vertices of G such that every vertex of V(G)D has a at least two neighbors in D. A total outer-independent dominating set of a graph G is a set D of vertices of G such that every vertex of G has a neighbor in D, and the set V(G)D is independent. The 2-domination (total outer-independent domination, respectively) number of a graph G is the minimum cardinality of a 2-dominating (total...
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Wyznaczanie stref efektywności kanałów dystrybucji na przykładzie wybranego producenta artykułów
PublicationWybór kanału dystrybucji zalicza się do decyzji strategicznych, ponieważ pod uwagę należy wziąć zarówno aspekty ekonomiczne, jak i te, które są związane z obsługą klienta. We współczesnych kanałach dystrybucji, które cechuje duża różnorodność wynikająca ze sposobu przepływu towarów z miejsca ich produkcji do miejsca konsumpcji, istotne znaczenie będzie miał sprawny i szybki przepływ strumieni finansowych, materiałowych i informacyjnych....
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Reliability assessment of truss towers using Monte Carlo Method, PEM and RSM
PublicationThe paper discusses reliability assessment of simple random truss structures using three different probabilistic methodologies: the Monte Carlo Method (MCM), the Point Estimate Method (PEM) and the Response Surface Method (RSM). A benchmark truss structure and a simplified full–size engineering tower are both analyzed. A set of ultimate load numerical calculations is performed and the results are taken as the basis of advanced...
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Analysis of sloping brace stiffness influence on stability and load bearing capacity of a truss
PublicationThe paper is focused on the numerical study of stability and load bearing capacity of a truss with side elastic braces. The structure is made in reality. The rotational and sliding brace stiffnesses were taken into account. Linear buckling analysis and non-linear static analysis with geometric and material nonlinearity were performed for the beam and shell model of the truss with respect to the angle of sloping braces. As a result...
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Stability and load bearing capacity of a braced truss under upward wind loading
PublicationThe paper is focused on the numerical and experimental investigation of stability of a steel truss under upward wind loading. The structure was stiffened by elastic braces situated at the top and bottom chord. Usually the lateral (translational) brace stiffness is considered. However, the rotational stiffness of braces caused by interaction between torsional stiffness of the truss top chord and bending stiffness of the roof elements...
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Stability and load bearing capacity of a braced truss under upward wind loading
PublicationThe paper is focused on the numerical and experimental investigation of stability of a steel truss under upward wind loading. The structure was stiffened by elastic braces situated at the top and bottom chord. Usually the lateral (translational) brace stiffness is considered. However, the rotational stiffness of braces caused by interaction between torsional stiffness of the truss top chord and bending stiffness of the roof elements...
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Psychological and physical components in forming preferences on urban greenery management – The case of trees
PublicationPublic opinion is increasingly important in managing urban greenery. In this regard, this study demonstrates the importance of sociological (environmental worldviews), psychological (place attachment, perceived benefits of trees), and physical factors (type of building people live in, and urban greenery) in forming residents’ opinions on whether the municipality or landowners should decide about tree removal on private land. Logistic...
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Some remarks about numerical stability in nonlinear dynamics on the basic of truss structures.
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Application of short-time GNSS solution geodynamical studies
PublicationThe paper presents the results of research related to the application of GNSS solutions in short observational periods in geodynamical investigations. Authors used the 3-hour solution appointed from hour-long interval of about 30 chosen stations on mountainous terrains from over 100 which were worked out. The main aim was to check the correctness of such solutions by the comparison with the daily ones. Some outliers in East component...
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Emotional distress, burnout and sense of safety during the COVID-19 pandemic in teachers after the reopening of schools
PublicationThe COVID-19 pandemic is having a significant impact on people's psychological well-being and mental health. This study aimed to identify factors linked to emotional distress, burnout and sense of safety in teachers related to the reopening of Polish schools after lockdown, remote work, and the holiday period between March and August 2020. A total of 1,286 teachers from different educational institutions participated in the...
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Hydrogeochemia strefy kontaktu wód słono-słodkich na wybrzeżu Bałtyku na przykładzie rejonu Ustki
PublicationOpisana strefa kontaktu wód słodkich ze słonymi w rejonie Ustki zachodzi w warunkach wnikania zasolonych wód kanału rzeki Słupi do płytkiej warstwy wodonośnej. Ta sytuacja zachodzi głownie w okresie podpiętrzenia wód kanału przez morze w czasie jesienno-zimowych sztormów. W Ustce stwierdzono wyraźną zmienność czasową i przestrzenną składu chemicznego wód podziemnych płytkiej warstwy wodonośnej. Wzrost stężeń mineralizacji ogólnej...
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Experiments and Numerical Simulations of the Annealing Temperature Influence on the Residual Stresses Level in S700MC Steel Welded Elements
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Grating Resonances on Periodic Arrays of Sub-wavelength Wires and Strips: From Discoveries to Photonic Device Applications
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Investigation of Parallel Data Processing Using Hybrid High Performance CPU + GPU Systems and CUDA Streams
PublicationThe paper investigates parallel data processing in a hybrid CPU+GPU(s) system using multiple CUDA streams for overlapping communication and computations. This is crucial for efficient processing of data, in particular incoming data stream processing that would naturally be forwarded using multiple CUDA streams to GPUs. Performance is evaluated for various compute time to host-device communication time ratios, numbers of CUDA streams,...
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The impact of surface slope and calculation resolution on the fractal dimension for fractures of steels after bending-torsion fatigue
PublicationThe article presents the results of the fractal dimension measurements on the fatigue fracture surfaces of 10HNAP and S355J2 steels specimens after combined bending-torsion fatigue. For smooth and ring-notched specimens, three loading conditions were analyzed: (1) bending; (2) bending-torsion; and (3) torsion fatigue. Post-failure surface topography measurements were carried out on the entire fracture surfaces using an optical...
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Hydrogen permeation through welded joints of S690QL steels at cathodic polarisation in sea water in the presence of SRB
PublicationPrezentowane są wyniki badan metodą Devanathana- Stachurskyego przenikania wodoru w wodzie morskiej w obecności bakterii redukujących siarczany i w warunkach sterylnych. Badania wykonano na stali S690QL poddanej symulowanym obróbkom cieplnym prowadzącym do struktur modelujących strefy wpływu ciepła. Stwierdzono dodatni wpływ obecności bakterii na przenikanie wodoru. Różnice między poszczególnymi próbkami były minimalne.
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Protection and renovation of public areas in a modernist city: the case of three streets in the historic City Centre of Gdynia
PublicationThis article concerns issues related to the preservation and restoration of public space in Gdynia’s city centre, which was designed and built mainly in the 1920s and 1930s. In 2007, a major part of the city centre was entered into the register of monuments asa historic complex of urban architecture. Moreover, in 2015, the area was declared a Monument of History. Protection of a complex of urban architecture covers not only the...
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Zarys przemian przestrzennych strefy reprezentacyjnej Gdańska na podstawie opracowań planistycznych od 1866 roku
PublicationStrefa Reprezentacyjna obejmuje obszar pokrywający się w dużej mierze z zachodnim frontem historycznego śródmieścia Gdańska. Wykształcona na przełomie XIX i XX wieku jako wielkomiejskie centrum miasta jest jedną z historycznie najbardziej kluczowych jego przestrzeni. Dziś to obszar zaniedbany i jakby zapomniany, zdominowany przez funkcje komunikacyjne, jakkolwiek nadal o dużym i niewykorzystanym potencjale. Przemiany przestrzenne...
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Evaluating the Catastrophic Rainfall of 14 July 2016 in the Catchment Basin of the Urbanized Strzyza Stream in Gdańsk, Poland
PublicationWe analyzed the causes, the course, and consequences of the extreme precipitation events that occurred 14 July 2016 in the watershed of Strzyza Creek in Gdańsk, Poland. Automated rain gauges located in Strzyża catchment registered a total precipitation lasting about 16 hours – from 129 to 160 mm of rain depth. More in-depth analysis based on rain data collected by Gdańsk University of Technology (GUT) rain station was done. The...
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INCREASING POWER SUPPLY SAFETY IN THE ASPECT OF SUPPORTING THE RENEWABLE ENERGY SOURCES BY CONVENTIONAL AND VIRTUAL POWER STORES
PublicationThis paper presents characteristics and purposefulness of supporting the renewable energy sources (OZE) by means of energy stores. The main emphasis was placed on analysis of virtual energy stores available for implementation in Polish economy conditions. A role which management of Demand Side Response (DSR) may play in balancing Polish electric power system, is discussed. Implementation of such solutions together with conventional...
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Idea określania strefy wpływów drgań komunikacyjnych w oparciu o algorytm sztucznej sieci neuronowej
PublicationW wielu dziedzinach nauk, również w budownictwie coraz częściej stosuje się metody przybliżone. Zazwyczaj są to metody pozwalające rozwiązać problemy inżynierskie w sposób na tyle dokładny, że z punktu widzenia inżynierii jest to zarówno wystarczalny jak i bardziej ekonomiczny wynik niż przy metodach tradycyjnych i bardziej dokładnych. Problemem badawczym będzie znalezienie prostego sposobu określania wpływu drgań na budynki tak,...
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Rola osobowości pracownika w radzeniu sobie ze stresem w pracy na stanowisku komputerowym
PublicationW artykule dokonano analizy wpływu osobowości pracownika na radzenie sobie ze stresem w pracy na stanowisku komputerowym. Wskazano możliwości modyfikacji wymagań, tak aby praca była dostosowana do szerokiej grupy zatrudnionych i wymagała minimalnego udziału szczególnych predyspozycji indywidualnych.
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Numerical estimation of flood zones in the Vistula River valley, Warsaw, Poland
PublicationPrzedstawiono studium dotyczące wyznaczenia stref zagrożenia powodziowego dla miasta Warszawy wskutek wezbrań rzeki Wisły. Do oszacowania zasięgu stref wykorzystano matematyczny model ustalonego przepływu wolnozmiennego oraz numeryczny model terenu doliny rzeki. Do zobrazowania uzyskanych wyników zastosowano system GIS. Na podstawie uzyskanych wyników zidentyfikowano obszary miasta Warszawy narażone na ewentualną powódź oraz odcinki...
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Effective highly accurate time integrators for linear Klein-Gordon equations across the scales
PublicationWe propose an efficient approach for time integration of Klein-Gordon equations with highly oscillatory in time input terms. The new methods are highly accurate in the entire range, from slowly varying up to highly oscillatory regimes. Our approach is based on splitting methods tailored to the structure of the input term which allows us to resolve the oscillations in the system uniformly in all frequencies, while the error constant...
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Effective highly accurate time integrators for linear Klein-Gordon equations across the scales
PublicationWe propose an efficient approach for time integration of Klein-Gordon equations with highly oscillatory in time input terms. The new methods are highly accurate in the entire range, from slowly varying up to highly oscillatory regimes. Our approach is based on splitting methods tailored to the structure of the input term which allows us to resolve the oscillations in the system uniformly in all frequencies, while the error constant...
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Innovative Bidirectional Isolated High-Power Density On-Board Charge for Vehicle-to-Grid
PublicationThis paper deals with developing and implementing a bidirectional galvanically isolated on-board charger of a high-power density. The power density of the new charger was 4 kW/kg and 2.46 kW/dm3, and the maximum efficiency was 96.4% at 3.4 kW. Due to the requirement to achieve a high-power density, a single-stage inverter topology was used. Regarding switching losses, due to the topology of the circuit with so-called hard switching,...