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Search results for: investigation of structures elements
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Analysis of Ceramic Elements with Ring-Crack Defects in Lubricated Rolling Contact
PublicationThe properties of ceramics, specifically low density, high hardness, high temperature capability and low coefficient of thermal expansion are of most interest to rolling element manufacturers. Surface ring cracks on lubricating rolling contact fatigue failure has been studied using numerical fracture analysis. Such cracks are very often found on ceramic bearing balls and decrease fatigue life rapidly. The numerical calculations...
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IMPACT OF THE ORGANISATION OF MEGA SPORTING EVENTS ON SELECTED ELEMENTS OF THE TOURISM SECTOR
PublicationIntroduction. In the world-wide literature, there is no unanimity in the assessment of the impact of mega sporting events on the tourism sector. Therefore, the main purpose of this study was to quantify the impact of mega sporting events on changes in tourist inflow and the amount of expenditure incurred by visitors. Material and methods. In this study, an ex-post analysis of many different categories of mega sporting events was...
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Propagation of guided elastic waves in shell-type aircraft structural elements
PublicationW pracy przedstawiony powłokowy spektralny element skończony do analizy zjawiska propagacji fal sprężystych w elementach konstrukcyjnych typu powłokowego.
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Propagation of elastic waves in structural elements by spectral finite element methods
PublicationW pracy przedstawiono metodę elementów spektralnych w zastosowaniu do analizy propagacji fal sprężystych w elementach konstrukcyjnych.
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The Role of Selected Trace Elements in Oxidoreductive Homeostasis in Patients with Thyroid Diseases
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The method of tribotesting of PVD coated elements in oscillation motion at high temperature
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Thermal properties of rare earth elements complexes with 1,3,5-benzenetricarboxylic acid
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Quasi-resonant dc-link inverter with a reduced number of active elements
PublicationW artykule przedstawiono nową topologię równoległego quasi-rezonansowego obwodu pośredniczącego falownika napięcia. Opisano sekwencje miękkiej komutacji falownika w dwukierunkowym trybie pracy falowniczej i prostowniczej. Analiza układu została zweryfikowana badaniami symulacyjnymi i eksperymentalnymi. Przedstawiona topologia odznacza się prostą strukturą oraz małą ilością elementów aktywnych. Dzięki zastosowaniu krzepkiej strategii...
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Optical recognition elements. Macrocyclic imidazole chromoionophores entrapped in silica xerogel
PublicationNowe chromojonofory zawierające fragment eteru koronowego i resztę azolu zostały unieruchomione w krzemionkowej matrycy żelowej metodą zol-żel i zbadane jako optyczne elementy rozpoznające kationy Li+,Cs+, Cu2+. Elementy optyczne oparte na 21-członowych pochodnych imidazolu i 4-metyloimidazolu rozpoznawały jony Li+ w roztworze wodnym. Wyznaczono parametry g i A na podstawie badań EPR dla kompleksów 18-członowej i 21-członowej pochodnej...
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Numerical analysis of behaviour of reinforced concrete elements under eccentric compression
PublicationPrzedstawiono wyniki modelowania nośności elementów żelbetowych stosując metodę elementów skończonych. Do opisu betonu zastosowano sprężysto-plastyczne prawo materiałowe wg Druckera-Pragera. Do modelowania stali zbrojeniowej zastosowano sprężysto-plastyczne prawo materiałowe według von Misesa. Obliczenia wykonano dla ścian żelbetowych.
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J. FE modelling of cracks in concrete elements within continuum mechanics.
PublicationW artykule przedstawiono wyniki symulacji rys zakrzywionych w elementach betonowych w warunkach mieszanego sposobu obciążenia. Symulacje wykonano przy zastosowaniu 3 różnych modeli: modelu sprężysto-plastycznego, modelu w ramach mechaniki zniszczeniowej i modelu z rysami obracającymi się.
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Numerical investigation on dynamic response of a steel lattice tower under various seismic events
PublicationThe present paper presents the results of the numerical study designed to investigate the soil-structure flexibility effects on modal parameters (i.e. fundamental frequencies) and time-history analysis response (represented by the top relative displacements) of a 46.8 m high steel lattice tower subjected to a number of ground motions including also one mining tremor. In addition to the fixed-base condition, three different soil...
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EM-Driven Multi-Objective Optimization of Antenna Structures in Multi-Dimensional Design Spaces
PublicationFeasible 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
PublicationIn 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.
PublicationA 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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Fragility analysis of structural pounding between adjacent structures arranged in series with various alignment configurations under near‑field earthquakes
PublicationA 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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Numerical investigations of discrete crack propagation in Montevideo splitting test using cohesive elements and real concrete micro-structure
PublicationThe paper is aimed at accurately predicting the discrete fracture process in concrete specimens under complex stress states in two dimensional (2D) simulations. Plain concrete specimens subjected to Montevideo splitting test (MVD) were used for consideration due to non-negligible shear stresses impact in this type of test. In order to reflect the heterogeneous nature of the concrete, the meso-structure of the samples was included...
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Sub-national structures matter when evaluating physical activity promotion: Lessons from Germany
PublicationBackground 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
PublicationPurpose 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
PublicationA 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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Non-Linear Analysis of Structures Utilizing Load-Discretization of Stiffness Matrix Method with Coordinate Update
PublicationThis 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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Closer look into the structures of tetrabutylammonium bromide–glycerol-based deep eutectic solvents and their mixtures with water
PublicationIn 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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On Improved-Reliability Design Optimization of High-Frequency Structures Using Local Search Algorithms
PublicationThe 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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Investigating the Effects of Geometrical Parameters of Re-Entrant Cells of Aluminum 7075-T651 Auxetic Structures on Fatigue Life
PublicationIn 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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Kriging metamodels and design re‐utilization for fast parameter tuning of antenna structures
PublicationThe 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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Shaking table experimental study on the effectiveness of polymer bearings for seismic isolation of structures
PublicationSeismic 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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An Investigation of Polyamides Based on Isoidide-2,5-dimethyleneamine as a Green Rigid Building Block with Enhanced Reactivity
PublicationNovel, semicrystalline polyamides and copolyamides were synthesized from a new carbohydrate-based diamine, namely isoidide-2,5-dimethyleneamine (IIDMA). In combination with 1,6-hexamethylene diamine (1,6-HDA) as well as the biobased sebacic acid (SA) or brassylic acid (BrA), the desired copolyamides were obtained via melt polymerization of the nylon salts followed by a solid-state polycondensation (SSPC) process. Depending on the...
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Experimental investigation of performance and emission characteristics of a miniature gas turbine supplied by blends of kerosene and waste tyre pyrolysis oil
PublicationFossil fuels are non-renewable sources of energy that could be depleted in the near future, giving rise to amajor energy crisis. Scientists from all over the world are working on new technologies to produce fuelnot only from renewable sources but also from waste. This article is concerned with: (i) waste tyremanagement by means of the pyrolysis process, (ii) investigation of physico-chemical parameters ofwaste tyre pyrolysis oil...
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Rapid Yield Estimation and Optimization of Microwave Structures Exploiting Feature-Based Statistical Analysis
PublicationIn 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
PublicationGuided 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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A New Approach for Investigating the Impact of Pesticides and Nutrient Flux from Agricultural Holdings and Land-Use Structures on Baltic Sea Coastal Waters
PublicationKnowledge related to land-use management impacts on the Baltic Sea ecosystem is limited. The constant release of pollutants into water bodies has resulted in water quality degradation. Therefore, only the innovative approaches integrated with research will provide accurate solutions and methods for proper environment management and will enable understanding and prediction of the impacts of land-use in the Baltic Sea region. Modelling...
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A Study of Mutual Coupling Suppression between Two Closely Spaced Planar Monopole Antenna Elements for 5G New Radio Massive MIMO System Applications
Publication5G NR (new radio) introduces the concept of massive MIMO (multiple-input-multiple-output) technology, in which a larger number of antenna arrays are installed on the transceiver. Due to the increased number of antenna elements allocated close to each other (approximately at half-wavelength distance), mutual coupling becomes a serious problem leading to performance degradation of the MIMO communication system. In this communication,...
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INVESTIGATION OF THE CHARACTERISTICS OF A LOWEMISSION GAS TURBINE COMBUSTION CHAMBER OPERATING ON A MIXTURE OF NATURAL GAS AND HYDROGEN
PublicationT his article is devoted to the investigation of the characteristics of a low-emission gas turbine combustion chamber, which can be used in Floating Production, Storage and Offloading (FPSO) vessels and operates on a mixture of natural gas and hydrogen. A new approach is proposed for modelling the processes of burning out a mixture of natural gas with hydrogen under preliminary mixing conditions in gaseous fuel with an oxidizer...
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Accurate Modeling of Antenna Structures by Means of Domain Confinement and Pyramidal Deep Neural Networks
PublicationThe 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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Novel 1,2,3-Triazole Derivatives as Mimics of Steroidal System—Synthesis, Crystal Structures Determination, Hirshfeld Surfaces Analysis and Molecular Docking
PublicationHerein, 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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Modal FEM Analysis of Ferrite Resonant Structures
PublicationThe finite-element method (FEM) is applied for modal analysis of ferrite-loaded spherical resonators. To improve the efficiency of the numerical calculations, the body-of-revolution (BOR) technique is utilized. Due to the frequency-dependent ferrite permeability, FEM leads to a nonlinear eigenvalue problem that is challenging to solve. To this end, Beyn’s method is proposed. The effectiveness of the proposed approach is confirmed...
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Meander microstrip line with defected ground structures
PublicationW artykule omówiono koncepcję miniaturyzacji sekcji linii mikropaskowej poprzez modyfikację brzegu linii oraz warstwy metalizacji masy. W pracy zaprezentowano projekt oraz wyniki eksperymentu sprzęgacza gałęziowego skonstruowanego w oparciu o linię meandrową z zaburzoną warstwą metalizacji masy. Pomierzone charakterystyki transmisyjne potwierdzają atrakcyjność zastosowanych metod redukcji zajmowanej przez układ powierzchni. Osiągnięto...
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Molecular structures of two E-azobenzocrown ethers
PublicationRentgenowska analiza strukturalna monokryształów posłużyła do scharakteryzowania struktury izomerów E dwóch azobenzokoron: 13- i 16-członowej. Oba związki krystalizują w układzie jednoskośnym. W komórce elementarnej, w każdym przypadku znajdują się dwie niezależne cząsteczki, różniące się konformacją, szczególnie łańcucha eterowego. Porównując konformacje ''wolnych'' makrocykli z konformacjami ich kompleksów z jonami metali wskazano,...
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Two pseudopolymorphs of licl trimers with semicubane structures
PublicationCząsteczki tytułowych związków w ciele stałym przyjmują strukturę semikubanów - jest to pierwsza tego typu struktura dla solwatowanego chlorku litu. Jej budowę można opisać jako kuban [Li4Cl4(OPEt3)4], w którym jedna z cząsteczek LiCl została usunięta. Brak tej cząsteczki, a dokładniej mostkującego atomu Li, powoduje deformację struktury kubanu. Naroża zdeformowanego kubanu stanowią trzy atomy litu pochodzące z LiCl oraz cztery...
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MAINTENANCE OF BASIC DRAINAGE STRUCTURES IN THE STARGARD DISTRICT
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Wavelet Analysis for Damage Identification in Composite Structures
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Factors that strengthen and weaken the identity of the cluster structures
PublicationThe main aim of this paper is the application of "identity" to the issues related to "clustering process" and particularly - to the cooperation in the clusters and the cluster initiatives. The authors distinguish these factors that have the greatest influence on the formation and maintenance of identity in mentioned networks of cooperation.
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Parameterized diagnostic module implemented in FPGA structures
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Special Issue: “Non-Destructive Testing of Structures”
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Functionality stored in the structures of cyclodextrin–porphyrinoid systems
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Wavelet analysis for damage identification in composite structures
Publicationw pracy zaproponowano metodę analizy sygnalu opartą o transformatę falkową, pozwalajacą na identyfikcaje pęknięcia zmęczeniowego w jednowymiarowych elementach konstrukcyjnych wykonanych z materialow kompozytowych
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Propagation of elastic waves in shell-like structures
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Damage detection in riveted structures by laser measurements
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Impedance measurements of coating properties on bridge structures
PublicationPomiary impedancyjne pozwalają na prostą ocenę właściwości ochronnych powłok ochronnych i wykładzin. Pomiary stosuje się w celu porównania powłok, monitorowania ich właściwości i oceny mechanizmu działania. Metodyka jest z powodzeniem stosowana w pomiarach laboratoryjnych. Pomiary terenowe są bardziej skomplikowane ponieważ wymagają w pełni kontrolowanych komputerowo przyrządów, kontroli warunków pogodowych oraz wielu innych parametrów...
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Design-oriented modeling of antenna structures by means of two-level kriging with explicit dimensionality reduction
PublicationThe employment of full-wave electromagnetic (EM) analysis is a practical necessity in the design of contemporary antenna structures. This is because simpler models are generally not available or of limited accuracy. At the same time, EM-based design is computationally expensive. Consequently, the ways of accelerating tasks such as parametric optimization or uncertainty quantification have to be sought. A possible workaround that...