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Wyniki wyszukiwania dla: reinforced concrete structures
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Canonic structures of odd-order elliptic Gm-C filters.
PublikacjaW pracy zaproponowano nowe rozwiązania układowe struktur kanonicznych eliptycznych filtrów Gm-C czasu ciągłego, rzedu nieparzystego. Opracowane struktury charakteryzują się małą liczbą elementów pasywnych oraz aktywnych i są przewidziane do zastosowań w filtrach niskomocowych o małej wrażliwości. W przeprowadzonych badaniach porównywano wybrane struktury 3-go rzędu pod względem właściwości i wymagań układów scalonych, w których...
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Characterization of wave structures containing sets of bow-tie resonators
PublikacjaArtykuł opisuje metodę analizy rozpraszania fali elektromagnetycznej układzie rezonatorów motylkowych w strukturach otwartych i zamkniętych. W artykule zaprezentowano przykłady aplikacji układów mikrofalowych zawierające opisywane elementy.
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Computational Bar Size Optimization of Single Layer Dome Structures Considering Axial Stress and Shape Disturbance
PublikacjaA computational method is proposed in this paper to minimize the material usage in the construction of modern spatial frame structures by prestressing a minimal number of members. The computational optimization is conducted in two steps. Firstly, a numerical model of a single-layer dome structure is used to minimize the cross-sectional area through several iterations. Different assumed ratios (r) ranging from 0.95 to 0.75 are multiplied...
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Cost-Efficient EM-Driven Size Reduction of Antenna Structures by Multi-Fidelity Simulation Models
PublikacjaDesign of antenna systems for emerging application areas such as the Internet of Things (IoT), fifth generation wireless communications (5G), or remote sensing, is a challenging endeavor. In addition to meeting stringent performance specifications concerning electrical and field properties, the structure has to maintain small physical dimensions. The latter normally requires searching for trade-off solutions because miniaturization...
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Towards Changes of Macro-Economic Structures in Middle Eastern Countries. Empirical Evidence for 1970–2018
PublikacjaMiddle East countries share a wide bundle of specific structural economic features and one of the latest is a high dependency of these economies on fossil fuels, which is quantitatively demonstrated through the share of oil and gas revenues in total export, but also in gross domestic product composition. This high economic dependency on natural resources on one hand has recently generated a material wealth of Middle Eastern countries...
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Cost-Efficient Surrogate Modeling of High-Frequency Structures Using Nested Kriging with Automated Adjustment of Model Domain Lateral Dimensions
PublikacjaSurrogate models are becoming popular tools of choice in mitigating issues related to the excessive cost of electromagnetic (EM)-driven design of high-frequency structures. Among available techniques, approximation modeling is by far the most popular due to its versatility. In particular, the surrogates are exclusively based on the sampled simulation data with no need to involve engineering insight or problem-specific knowledge....
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Reliable data-driven modeling of high-frequency structures by means of nested kriging with enhanced design of experiments
PublikacjaData-driven (or approximation) surrogate models have been gaining popularity in many areas of engineering and science, including high-frequency electronics. They are attractive as a way of alleviating the difficulties pertinent to high computational cost of evaluating full-wave electromagnetic (EM) simulation models of microwave, antenna, and integrated photonic components and devices. Carrying out design tasks that involve massive...
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Manufacturing and investigation of surface morphology and optical properties of composite thin films reinforced by TiO2, Bi2O3 and SiO2 nanoparticles
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Processing and characterization of reinforced polyethylene composites made with lignocellulosic fibres isolated from waste plant biomass such as hemp
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FBG Strain Monitoring of a Road Structure Reinforced with a Geosynthetic Mattress in Cases of Subsoil Deformation in Mining Activity Areas
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Strength parameters of polyester reinforced PVC coated fabric after short term creep loading in biaxial mode
PublikacjaThis study addresses the analysis of tensile strength parameters of the technical fabric VALMEX, which is composed of two orthogonal polyester thread families (named the warp and fill) and both sides PVC coated. The material was firstly subjected to 48-hour biaxial creep loading with the equal stress level in both orthogonal directions of the fabric. The stress levels were established as follows: 4.6 kN/m, 10.4 kN/m, 16.4 kN/m,...
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Scalability of surrogate-assisted multi-objective optimization of antenna structures exploiting variable-fidelity electromagnetic simulation models
PublikacjaMulti-objective optimization of antenna structures is a challenging task due to high-computational cost of evaluating the design objectives as well as large number of adjustable parameters. Design speedup can be achieved by means of surrogate-based optimization techniques. In particular, a combination of variable-fidelity electromagnetic (EM) simulations, design space reduction techniques, response surface approximation (RSA) models,...
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Fast multi-objective optimization of antenna structures by means of data-driven surrogates and dimensionality reduction
PublikacjaDesign of contemporary antenna structures needs to account for several and often conflicting objectives. These are pertinent to both electrical and field properties of the antenna but also its geometry (e.g., footprint minimization). For practical reasons, especially to facilitate efficient optimization, single-objective formulations are most often employed, through either a priori preference articulation, objective aggregation,...
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Changes on the Surface of the SiO2/C Composite, Leading to the Formation of Conductive Carbon Structures with Complex Nature of DC Conductivity
PublikacjaSol–gel layers have been the subject of many studies in recent decades. However, very little information exists about layers in which carbon structures are developed in situ. Using the spin-coating method, we obtained thin iron-doped SiO2/C composite films. The results of Raman spectroscopy showed that our samples consisted of graphitic forms and polymers. The latter’s contribution decreases with rising temperature. FTIR and EDS...
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Determination of Vehicles Load Equivalency Factors for Polish Catalogue of Typical Flexible and Semi-rigid Pavement Structures
PublikacjaThe new Polish Catalog of Typical Flexible and Semi-rigid Pavement Structures was introduced to use in practice in 2014. Much of works were focused on actualization of vehicles load equivalency factors. For this purpose data delivered from weigh-inmotion were analyzed. Four methods of determination of load equivalency factors for pavement structure design were compared. The analysis showed that fourth power equation, AASHTO 1993...
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Variable Data Structures and Customized Deep Learning Surrogates for Computationally Efficient and Reliable Characterization of Buried Objects
PublikacjaIn this study, in order to characterize the buried object via deep-learning-based surrogate modeling approach, 3-D full-wave electromagnetic simulations of a GPR model has been used. The task is to predict simultaneously and independent of each characteristic parameters of a buried object of several radii at different positions (depth and lateral position) in various dispersive subsurface media. This study has analyzed variable...
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Dispersive Delay Structures With Asymmetric Arbitrary Group-Delay Response Using Coupled-Resonator Networks With Frequency-Variant Couplings
PublikacjaThis article reports the design of coupled-resonatorbased microwave dispersive delay structures (DDSs) with arbitrary asymmetric-type group delay response. The design process exploits a coupling matrix representation of the DDS circuit as a network of resonators with frequency-variant couplings (FVCs). The group delay response is shaped using complex transmission zeros (TZs) created by dispersive cross-couplings. We also present an...
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Low-Cost and Precise Automated Re-Design of Antenna Structures Using Interleaved Geometry Scaling and Gradient-Based Optimization
PublikacjaDesign of contemporary antennas is an intricate endeavor involving multiple stages, among others, tuning of geometry parameters. In particular, re-designing antennas to different operating frequencies, makes parametric optimization imperative to ensure the best achievable system performance. If the center frequency at the current design is distant from the target one, local tuning methods generally fail, whereas global algorithms...
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Coordination complexes of Mn(II), Co(II), Ni(II), Zn(II) and Cd(II) with histaminol – Crystal structures and formation constants in aqueous solution
PublikacjaStability constants were determined for a series of coordination complexes of Mn(II), Co(II), Ni(II), Zn(II) and Cd(II) with histaminol in aqueous solution. The tendency of histaminol to form chelate complexes has been confirmed by the isolation of several complex species in the monocrystalline form and determination of their molecular structures.
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Proton transfer and hydrogen bonds in supramolecular, self-assembled structures of imidazolium silanethiolates. X-ray, spectroscopic and theoretical studies
PublikacjaThe reaction of 1-methylimidazole, 2-ethyl-4-methylimidazole and 2-ethylimidazole with tris(2,6- diisopropylphenoxy)silanethiol (TDST) leads to the formation of three new salts, which have been characterized by elemental analyses, thermogravimetric analyses, FTIR spectroscopy, and their structures were determined by single-crystal X-ray diffraction. Structural analyses indicate that in all three compounds a proton transfer has...
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Application of extended Finite Element Method to cracked concrete elements - numerical aspects
PublikacjaArtykuł omawia zastosowanie rozszerzonej metody elementów skończonych do zarysowanych elementów betonowych. Obliczenia wykonano dla elementów poddanych zginaniu i mieszanemu ściskaniu - rozciąganiu. Wyniki porównano z doświadczeniami.
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Impact of reclaimed asphalt pavement (RAP) on low-temperature properties of asphalt concrete
PublikacjaHot mix recycling is a practice which enables reusing materials from old asphalt pavements. Current Polish regulations allow usage of RAP only for binder and base courses, and its amount is limited. Asphalt mixtures with RAP material have to fulfil requirements stated for typical asphalt mixtures. The research presents low-temperature properties of twelve different asphalt concretes with RAP material, determined using three-point...
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Investigation of Durability Properties for Lightweight Structural Concrete with Hemp Shives Instead of Aggregate
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The influence of texturing of the surface of concrete substrate on its adhesion to cement mortar overlay
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The quality management in precast concrete production and delivery processes supported by association analysis
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DEM modelling of concrete fracture based on its structure micro-CT images
PublikacjaW rozdziale książki zawarto numeryczne wyniki mezoskopowe dotyczące postępującego pękania betonu na poziomie kruszywa. Do badania procesu pękania belki betonowej z karbem w trzech (3D) i dwóch (2D) wymiarach zastosowano metodę elementów dyskretnych (DEM). Niejednorodność betonu uwzględniono stosując czterofazowy opis: kruszywo, zaprawa, makropustki i międzyfazowe strefy przejściowe. W obliczeniach DEM na podstawie zdjęć rentgenowskich...
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Effect of aggregate structure on fracture process in concrete using 2D lattice model
PublikacjaArtykuł przedstawia symulacje rys w betonie przy zastosowaniu nowego modelu siatkowego. Zbadano wpływ rozkładu i wielkości kruszywa oraz wpływ strefy kontaktu na nośność i propagacje rys. Obliczenia były dwuwymiarowe.
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Measurements and calculations of the width of the fracture process zones on the surface of notched concrete beams
PublikacjaArtykuł omawia wyniki pomiaru i analizy numerycznej szerokości strefy pękania w belkach betonowych z nacięciem. Do pomiarów zastosowano metodę DIC. Do symulacji zastosowano model sprężysto - plastyczny i model z degradacją sztywności. Oba modele zostały rozszerzone o nielokalne osłabienie. Wyniki symulacji porównano z doświadczeniami.
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Modelling of size effects in concrete using elasto-plascity with non-local softening
PublikacjaArtykuł przedstawia numeryczne symulacje MES efektów skali w materiałach kruchych takich jak beton , wykonane w warunkach płaskiego stanu odkształceń. Materiał był modelowany w ramach sprężysto-plastyczności z izotropowym wzmocnieniem i osłabieniem. W obszarze ściskania przyjęto liniowe kryterium Druckera-Pragera z niestowarzyszonym prawem płynięcia a w obszarze rozciągania liniowe kryterium Rankina ze stowarzyszonym prawem płynięcia....
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Discrete modeling of micro-structure evolution during concrete fracture using DEM
PublikacjaW artykule pokazano wyniki dyskretne DEM dla betonu poddanego ściskaniu i rozciąganiu jednoosiowemu. Wyniki siła-przemieszczenie i zarysowania porównano z doświadczeniami. Szczególną uwagę zwrócono na zjawiska mikrostrukturalne podczas zarysowania na poziomie kruszywa.
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Model Management for Low-Computational-Budget Simulation-Based Optimization of Antenna Structures Using Nature-Inspired Algorithms
PublikacjaThe primary objective of this study is investigation of the possibilities of accelerating nature-inspired optimization of antenna structures using multi-fidelity EM simulation models. The primary methodology developed to achieve acceleration is a model management scheme which the level of EM simulation fidelity using two criteria: the convergence status of the optimization algorithm, and relative quality of the individual designs...
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Enhanced electrochemical activity of boron-doped nanocarbon functionalized reticulated vitreous carbon structures for water treatment applications
PublikacjaAn extraordinary charge transfer kinetics and chemical stability make a boron-doped diamond (BDD) a prom- ising material for electrochemical applications including wastewater treatment. Yet, with flat geometrical sur- faces its scaling options are limited. In this study, the reticulated Vitreous Carbon (RVC) served as a substrate for boron-doped diamondized nanocarbons (BDNC) film growth resulting with complex heterogeneity carbon structures...
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Rapid Variable-Resolution Parameter Tuning of Antenna Structures Using Frequency-Based Regularization and Sparse Sensitivity Updates
PublikacjaGeometry parameter tuning is an inherent part of antenna design process. While most often performed in a local sense, it still entails considerable computational expenses when carried out at the level of full-wave electromagnetic (EM) simulation models. Moreover, the optimization outcome may be impaired if good initial design is not available. This paper proposes a novel approach to fast and improved-reliability gradient-based...
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Multilayered structures examination using polarization sensitive optical coherence tomography
PublikacjaW artykule przedstawiono wstępne wyniki badań struktur warstwowych z użyciem systemu optycznej tomografii koherentnej z analizą stanu poaryzacji (PS-OCT). Omówiono budowę systemu oraz zakres stosowalności metody do badania złożonych struktur warstwowych.
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Study of structures and properties of the laser cladding exhaust valve after service
PublikacjaPrzylgnie zaworów wydechowych silnie obciążonego silnika okrętowego zostały pokryte warstwą wykonana ze stopu kobaltu za pomocą techniki napawania laserowego. Tak przygotowane zawory były eksploatowane przez 3000 godzin w silniku Daru Młodzieży. Po tym czasie zostały zdemontowane i poddane szczegółowej analizie. Warunki pracy spowodowały powstanie na powierzchni przylgni warstwy tlenków o różnej grubości, wykazującej skłonność...
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Accurate modelling of microwave structures using shape-preserving response prediction
PublikacjaArtykuł prezentuje metodologię dokładnego modelowania struktur mikrofalowych. Jest to zmodyfikowana wersja techniki opartej na procedurze przewidywania odpowiedzi z zachowaniem kształtu (shape-preserving response prediction, SPRP), która oszacowuje odpowiedź struktury mikrofalowej otrzymanej poprzez kosztowną obliczeniowo symulację elektromagnetyczną za pomocą taniego obliczeniowo modelu tejże struktury. Modyfikacja polega na wykorzystaniu...
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Pounding of structures during earthquakes modelled by nonlinear viscoelastic impact element.
PublikacjaAnalizowano zderzenia konstrukcji budowlanych podczas trzęsień ziemi wykorzystując model lepkosprężysty siły zderzenia. W analizie, zachowanie konstrukcji o różnych własnościach dynamicznych symulowane jest modelem dyskretnym o skupionych masach. wyniki badań pokazują, iż zderzenie może prowadzić do znacznego wzrostu odpowiedzi konstrukcji mniej sztywnej i lżejszej.
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Technologies for Joining and Forming Thin-Walled Structures in the Construction of Transportation Vehicles
PublikacjaEditorial
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The use of Response Surface Methodology for reliability estimation of composite engineering structures
PublikacjaStability loss is one of the key issues in the analysis of shells made of composite materials. This paper aims at finding the variation of the critical or limit value of the load resulting from geometric imperfections. An axially compressed 16-layer cylindrical panel model is considered. The imperfections of the panel are simulated as random fields. The parameters of these fields are used as the basic variables of the reliability...
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Numerical modelling of moored floating structures using SPH. Preliminary results
PublikacjaThis article presents partial results of the works carried out under the research project "The development of the methodof modeling the dynamics of the floating (offshore) objects subjected to the environment influence", which aims at developing computational methods for modeling the dynamics of offshore structures.The article contains the description of the method of modeling the hydrodynamic impacts using SPH method and the description...
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Path-based methods on categorical structures for conceptual representation of wikipedia articles
PublikacjaMachine learning algorithms applied to text categorization mostly employ the Bag of Words (BoW) representation to describe the content of the documents. This method has been successfully used in many applications, but it is known to have several limitations. One way of improving text representation is usage of Wikipedia as the lexical knowledge base – an approach that has already shown promising results in many research studies....
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Centralized and Distributed Structures of Intelligent Systems for Aided Design of Ship Automation
PublikacjaA design process and accepted solutions made during this process, often base on non-formalized knowledge, obtained from designer (expert) intuition and practice. There are no formalized rules assuring the correctness of design solutions. The analysis of design process of ship automation, including ship power system, shows that this process can be supported by application of the artificial intelligence elements. The article presents...
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Environmental aspects of coastal earth structures made of soil-ash composites
PublikacjaThis paper presents an innovative technology of building the coastal dams with the use of soil-ash composites. A natural- scale test stand and results of the performed environmental tests are presented ; they have been compared with standards for purity of soils and waters. Also, an analysis of the obtained results and discussion of trends and anomalies in the observations, are given.
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A Stabilized Complex LOBPCG Eigensolver for the Analysis of Moderately Lossy EM Structures
PublikacjaThis letter proposes a stabilized locally optimal block preconditioned conjugate gradient method for computing selected eigenvalues for complex symmetric generalized non-Hermitian eigenproblems. Effectiveness of the presented approach is demonstrated for a moderately lossy dual-mode dielectric resonator, modeled using finite-element method with higher order elements
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On EM-driven size reduction of antenna structures with explicit constraint handling
PublikacjaSimulation-driven miniaturization of antenna components is a challenging task mainly due to the presence of expensive constraints, evaluation of which involves full-wave electromagnetic (EM) analysis. The recommended approach is implicit constraint handling using penalty functions, which, however, requires a meticulous selection of penalty coefficients, instrumental in ensuring optimization process reliability. This paper proposes...
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Probabilistic limit state analysis of framed structures. The Monte Carlo simulation.
PublikacjaW pracy opisana jest koncepcja rozkładu prawdopodobieństwa stanu granicznego konstrukcji, oparta na specjalnej procedurze symulacyjnej Monte Carlo. Główną ideę stanowi obliczenie mnożnika obciażenia granicznego w każdym kroku symulacyjnym. Niezawodnosć lub prawdopodobieństwo awarii konstrukcji sa charakterystykami rozkładu prawdopopdobieństwa stanu granicznego. Szczegółowo opisano dwa warianty symulacji.
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Probability of limit state of bar structures. A modified Monte Carlo procedure
PublikacjaPraca poświecona jest zagadnieniom niezawodności i probabilistycznej analizie stanów granicznych układów prętowych. Główną ideę pracy stanowi rozkład prawdopodobieństwa stanu granicznego nośności ustroju, zdefiniowany na podstawie specjalnej procedury symulacyjnej Monte Carlo. W procedurze tej istotne jest wyznaczanie mnożników obciążenia granicznego w każdym kroku symulacyjnym. Charakterystykami rozkładu prawdopodobieństwa stanu...
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Application of decision–making parametric structures in the analysis of a compound planetary gear
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An Approximate Linear Analysis of Structures Utilizing Incremental Loading of Force Method
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A concept of an application to plan the time lines of building selected bridge structures
PublikacjaW rozdziale został przedstawiony przykład autorskiego programu komputerowego przeznaczonego do planowania czasu pracy i kosztów w budownictwie mostowym. Zaletą programu jest możliwość przedstawienia wyników w formie graficznej w sposób deterministyczny i niedeterministyczny. Ma to ogromne znaczenie jeżeli poszukujemy optymalnych rozwiązań dotyczących zagadnień ryzyka i ekonomiki budownictwa.