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Wyniki wyszukiwania dla: dynamics of metal structures
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Applying molecular dynamics simulation to take the fracture fingerprint of polycrystalline SiC nanosheets
PublikacjaGraphene-like nanosheets are the key elements of advanced materials and systems. The mechanical behavior of the structurally perfect 2D nanostructures is well documented, but that of polycrystalline ones is less understood. Herein, we applied molecular dynamics simulation (MDS) to take the fracture fingerprint of polycrystalline SiC nanosheets (PSiCNS), where monocrystalline SiC nanosheets (MSiCNS) was the reference nanosheet....
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Filtering EBG Structures Implemented in Coplanar Waveguide Feedline of Planar Slot Antenna
PublikacjaA novel compact dual-band slot antenna fed by a coplanar waveguide (CPW) incorporating electromagnetic band gap (EBG) structures has been proposed. At first, a classic wideband slot antenna fed by a CPW, dedicated to work in 2 ÷ 18 GHz band, has been designed. Subsequently, by adding simple EBG filtering structures into a CPW feedline, a dual-band performance ranging from 2.5 to 5.3 GHz and from 13.5 to 16.3 GHz, with the voltage...
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The dynamics of the total output of the Japanese fisheries sector: An analysis using input-output approach
PublikacjaThe purpose of this study is to investigate the dynamics of the total output of the fisheries industry when the changes of the final demand occur. This study focuses on the case of Japan. This study employs a demand-pull Input-Output (IO) quantity model, one of the calculation instruments in the IO analysis, as an analysis tool. Two conditions are included in calculation and analysis parts, namely (1) “whole sector change”, and...
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Timber - material of the future. Examples of small wooden architecture structures.
PublikacjaThe aim of this article is to present various types of wood-based products, classified as engineered timber, while specifying the implications of their structural properties for their forms. Timber is used as a construction material due to its fire resistance, good structural characteristics and insulating properties. The advent of new technologies of wood processing and wood-based materials production has converted timber into...
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Effective method for determining environmental loads on supporting structures for offshore wind turbines
PublikacjaThis paper presents a description of an effective method for determining loads due to waves, current and wind acting on the supporting structures of the offshore wind turbines. This method is dedicated to the structures consisting of the cylindrical or conical elements as well as (truncates) pyramids of polygon with a large number of sides (8 or more). The presented computational method is based on the Morison equation, which was...
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Effective method for determining environmental loads on supporting structures for offshore wind turbines
PublikacjaThis paper presents a description of an effective method for determining loads due to waves and current acting on the supporting structures of the offshore wind turbines. This method is dedicated to the structures consisting of the cylindrical or conical elements as well as (truncates) pyramids of polygon with a large number of sides (8 or more). The presented computational method is based on the Morison equation, which was originally...
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Optimal reshaping and stress controlling of double-layer spherical structures under vertical loadings
PublikacjaOptimal reshaping and stress controlling of double-layer spherical structures under vertical loadings
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Preventing of earthquake-induced pounding between steel structures by using polymer elements – experimental study
PublikacjaPounding between two, or more, adjacent buildings during earthquakes has been identified as one of the reasons for substantial damage or even total collapse of colliding structures, so it has been the subject of numerous studies in the recent years. A major reason leading to interactions between adjacent, insufficiently separated structures results from the differences in their dynamic properties. A number of different methods...
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Accurate simulation-driven modeling and design optimization of compact microwave structures
PublikacjaCost efficient design optimization of microwave structures requires availability of fast yet reliable replacement models so that multiple evaluations of the structure at hand can be executed in reasonable timeframe. Direct utilization of full-wave electromagnetic (EM) simulations is often prohibitive. On the other hand, accurate data-driven modeling normally requires a very large number of training points and it is virtually infeasible...
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Evaluation the P-Delta Effect on Collapse Capacity of Adjacent Structures Subjected to Far-field Ground Motions
PublikacjaIn urban areas, adjacent structures can be seen in any insufficient distance from each other, because of economic reasons and refusal of acquired minimum separation distance according to seismic previsions. Collapse capacity assessment of structures is one of the important objectives of performance-based seismic engineering. The purpose of this study is to consider the pounding phenomenon and P-Delta effect in seismic collapse...
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Independent dynamics of slow, intermediate, and fast intracranial EEG spectral activities during human memory formation
PublikacjaA wide spectrum of brain rhythms are engaged throughout the human cortex in cognitive functions. How the rhythms of various low and high frequencies are spatiotemporally coordinated across the human brain during memory processing is inconclusive. They can either be coordinated together across a wide range of the frequency spectrum or induced in specific bands. We used a large dataset of human intracranial electroencephalography...
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Entropic Measures of Complexity of Short-Term Dynamics of Nocturnal Heartbeats in an Aging Population
PublikacjaTwo entropy-based approaches are investigated to study patterns describing differences in time intervals between consecutive heartbeats. The first method explores matrices arising from networks of transitions constructed following events represented by a time series. The second method considers distributions of ordinal patterns of length three, whereby patterns with repeated values are counted as different patterns. Both methods provide...
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Bacterial Community Structures in Freshwater Polar Environments of Svalbard
PublikacjaTwo thirds of Svalbard archipelago islands in the High Arctic are permanently covered with glacial ice and snow. Polar bacterial communities in the southern part of Svalbard were characterized using an amplicon sequencing approach. A total of 52,928 pyrosequencing reads were analyzed in order to reveal bacterial community structures in stream and lake surface water samples from the Fuglebekken and Revvatnet...
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Modulated crystal structures - periodicity in more than three dimensions
PublikacjaThe initial definition of a crystal was that it is an object with flat faces. When diffraction studies were developed it turned out that crystal consists of a highly ordered particles and it is possible to isolate a small unique part of their structure - a unit cell - and the definition has been changed to rely on this fact. Nowadays by a crystal we mean any solid having an essentially discrete diffraction diagram. It is because...
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Novel microstrip low-pass filters with fractal defected ground structures
PublikacjaIn this study, three microstrip low-pass filters (LPFs) containing fractal-shaped defected ground structures have been designed and manufactured. To improve the performance of microstrip LPF, cascades of inductively coupled fractal resonators have been applied. Simultaneously, to achieve relatively constant microstrip impedance resulting in essentially low reflection losses, a modification of the strip geometry has been introduced....
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Modelling of foundations for supporting structures.
PublikacjaW pracy przedstawiono problemy współpracy fundamentów konstrukcji wsporczych z otaczającym ośrodkiem gruntowym w warunkach przestrzennego stanu odkształcenia. Przedstawiono możliwości analizy odporu granicznego podłoża i przemieszczeń fundamentów sztywnych obciążonych siłą poziomą lub momentem. Porównano modelowanie fizyczne zjawisk z modelowaniem matematycznym z wykorzystaniem symulacji numerycznych opartych na analizie płaskiego...
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On constructional solutions for tensile structures
PublikacjaW pracy zebrano i opisano kilka wybranych rozwiazań konstrukcyjnych stosowanych powszechnie w membranowych konstrukcjach wiszących.
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Teleportation of geometric structures in 3D
PublikacjaThe simplest quantum teleportation algorithms can be represented in geometric terms in spaces of dimensions 3 (for real state vectors) and 4 (for complex state vectors). The geometric representation is based on geometric-algebra coding, a geometric alternative to the tensor-product coding typical of quantum mechanics. We discuss all the elementary ingredients of the geometric version of the algorithm: geometric analogs of states...
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Numerical Modelling of Structures with Uncertainties
PublikacjaThe nature of environmental interactions, as well as large dimensions and complex structure of marine offshore objects, make designing, building and operation of these objects a great challenge. This is the reason why a vast majority of investment cases of this type include structural analysis, performed using scaled laboratory models and complemented by extended computer simulations. The present paper focuses on FEM modelling...
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On aspects of tensile structures analysis.
PublikacjaW pracy dokonano omówienia podstawowych aspektów analizy konstrukcji napiętych. Przedstawiono krótki rys historyczny tego typu konstrukcji, zwracając uwagę m.in. na konstrukcje membranowe, cięgnowe, pneumatyczne.
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Silanethiolates - synthesis, properties and structures.
PublikacjaW pracy wskazano podstawowe drogi syntezy oraz podano zwięzłą charakterystykę silanotiolanów - w większości związków kompleksowych posiadających jako główny ligand grupę silanotiolanową, na ogół (t-BuO)3SiS. Przy pomocy odpowiednio dobranych przykładów zilustrowano właściwości tych związków - wskazano ciekawsze elementy struktury molekularnej oraz specyficzne cechy spektralne.
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Robust Parameter Tuning of Antenna Structures by Means of Design Specification Adaptation
PublikacjaParameter tuning through numerical optimization has become instrumental in the design of high-performance antenna systems. Yet, practical optimization faces several major challenges, including high cost of massive evaluations of antenna characteristics, normally involving full-wave electromagnetic (EM) analysis, large numbers of adjustable variables, the shortage of reasonable initial solutions in the case of topologically complex...
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Trust Dynamics Analysis of CTR Scheme Subversion under Virtual Anonymity and Trust-Unaware Partner Selection
PublikacjaWe propose a framework to study Markovian trust value dynamics in a centralized Computational Trust and Reputation (CTR) scheme under trust-unaware partner selection using a mean-value approximation. Analytically founded answers are sought to questions like: Can dishonest agents subvert the CTR scheme (i.e., acquire higher trust values than honest agents)? Is indirect reciprocity incentivized? Is there a qualitative impact of a...
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Structures for parameterization, meshing and data exchange of topologically related surfaces of a ship hull
PublikacjaThis paper presents proposal of data structures for storage and processing of a parametric three-dimensional model of a midship hull sections. The model consists of coarse surfaces like: decks, frames, girders, stiffeners, brackets, partitions etc. bounded by topological relations. All workshop details are omitted as the model is intended for numeric calculations. Proposed data structures are prepared to facilitate changes in the...
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Unusual dynamics and nonlinear thermal self-focusing of initially focused magnetoacoustic beams in a plasma
PublikacjaUnusual thermal self-focusing of two-dimensional beams in plasma which axis is parallel to the equilibrium straight magnetic field is considered. The equi- librium parameters of plasma determine scenario of a beam divergence (usual or unusual) which is stronger as compared with a flow without magnetic field. Nonlinear thermal self-action of a magnetosonic beam behaves differently in the ordinary and unusual cases. Damping of wave...
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Influence of separation gap on the response of colliding models of steel structures under seismic and paraseismic excitations
PublikacjaAs a result of high urbanization, the need to erect closely-spaced buildings forces designers to consider collisions between structures taking place during ground motions. Experimental and numerical studies have confirmed that such collisions (often referred to as structural pounding) may cause serious damage to the structural elements and even lead to total collapse of colliding structures. The main reason of earthquake-induced...
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From structures to landscapes – towards re-conceptualization of the urban condition
PublikacjaThis paper presents an original approach towards the phenomena of re-naturalization of cities and indicates its possible consequences for the urban design and planning strategies. It focuses on the ongoing shift “from structures to landscapes” in understanding urban conditions. While modern architecture introduced geomet-ric compositions against the background of nature, early modern theories of architects and sociologists started...
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Scattering and Propagation Analysis for the Multilayered Structures Based on Field Matching Technique
PublikacjaA semi-analytical method is employed to the analysis of scattering and guiding problems in multilayer dielectric structures. The approach allows to investigate objects with arbitrary convex cross section and is based on the direct field matching technique involving the usage of the field projection at the boundary on a fixed set of orthogonal basis functions. For the scattering problems the scattered field in the far zone is calculated...
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Calculation of Resonance in Planar and Cylindrical Microstrip Structures Using a Hybrid Technique
PublikacjaA hybrid technique was employed for the analysis of the resonance frequency of thin planar and cylindrical microstrip structures with the patches of arbitrary geometry. The proposed technique utilizes a combination of Galerkin’s moment method and a finite-element method (FEM). In this approach, an FEM is adopted to calculate the patch surface current densities, and a method of moments is utilized to calculate the resonance frequencies...
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Minimization of vibrations during milling of flexible structures using mechatronic design techniques
PublikacjaThe paper presents an innovative effective method of minimizing vibrations during milling of flexible structures, using a new vibration suppression method based on a workpiece holder with adjustable support stiffness. The proposed method is rooted in mechatronic design techniques, which can become a standard procedure for optimizing the milling process.
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Guided Wave Propagation in Detection of Partial Circumferential Debonding in Concrete Structures
PublikacjaThe following article presents results of investigating the damage detection in reinforced concrete beams with artificially introduced debonding between the rod and cover, using a non-destructive method based on elastic waves propagation. The primary aim of the research was to analyze the possible use of guided waves in partial circumferential debonding detection. Guided waves were excited and registered in reinforced concrete...
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Enhanced visible light-activated gas sensing properties of nanoporous copper oxide thin films
PublikacjaMetal oxide gas sensors are popular chemoresistive sensors. They are used for numerous tasks, including environmental and safety monitoring. Some gas-sensing materials exhibit photo-induced properties that can be utilized for enhanced gas detection by modifying the sensor selectivity and sensitivity when illuminated by light. Here, we present the gas sensing characteristics of highly nanoporous Cu2O thin films towards both electrophilic...
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Effect of copper and silver modification of NH2-MIL-125(Ti) on the photoreduction of carbon dioxide to formic acid over this framework under visible-light irradiation
PublikacjaCu and Ag enhance the photocatalytic activities of metal–organic frameworks (MOFs) toward CO2 conversion because of their CO2 adsorption capacities and effects on the lowest unoccupied molecular orbital (LUMO) overpotentials of MOFs. However, to date, targeted introduction of metals into MOFs to achieve visible (Vis)- light-active photocatalysts for CO2 photoconversion has not been realized. Herein, a series of aminefunctionalized...
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Development of SPME fiber coatings with tunable porosity for physical confinement of ionic liquids as an extraction media
PublikacjaExtending the use of ionic liquids in sample preparation techniques remains a challenge. This paper presents procedures enabling the easy application of ionic liquids to the SPME technique. For this purpose, two approaches for producing a porous silica coating on a metal rod were investigated. Two silica precursor and porogen systems were used in the research: K2SiO3 + Formamide and Tetramethyl-orthosilicate + Polyethylene oxide....
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Cu-Doped Layered Double Hydroxide Constructs the Performance-Enhanced Supercapacitor Via Band Gap Reduction and Defect Triggering
PublikacjaLayered double hydroxides (LDHs) are regarded as the excellent electrode materials for supercapacitors because of their high theoretical capacitance and abundance. However, the poor conductivity and limited reaction kinetics of LDHs restrict their practical application severely. Herein, Cu is chosen from groups VIII/IB/IIB as dopants for Co-based LDH (CuCo-LDH). The designed metal–organic framework-derived hierarchical CuCo-LDH...
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Investigation of Performance and Configuration of a Selected IoT System—Middleware Deployment Benchmarking and Recommendations
PublikacjaNowadays Internet of Things is gaining more and more focus all over the world. As a concept it gives many opportunities for applications for society and it is expected that the number of software services deployed in this area will still grow fast. Especially important in this context are properties connected with deployment such as portability, scalability and balance between software requirements and hardware capabilities. In...
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Sea spray as a secondary source of chlorinated persistent organic pollutants? - Conclusions from a comparison of seven fresh snowfall events in 2019 and 2021
PublikacjaSecondary sources of persistent organic pollutants (POPs) gain in importance worldwide as primary sources decline. In this work, we aim to determine whether sea spray may be a secondary source of chlorinated POPs to the terrestrial Arctic, since a similar mechanism was proposed there only for the more water-soluble POPs. To this end, we have determined polychlorinated biphenyls and organochlorine pesticides concentrations in fresh...
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Superconductivity in the Cu(Ir1-xPtx)2Se4 spinel
PublikacjaWe report the observation of superconductivity in the CuIr2Se4 spinel induced by partial substitution of Pt for Ir. The optimal doping level for superconductivity in Cu(Ir1-xPtx )2Se4 is x = 0.2, where Tc is 1.76 K. A superconducting Tc vs composition dome is established between the metallic, normal conductor CuIr2Se4 and semiconducting CuIrPtSe4. Electronic structure calculations show that the optimal Tc occurs near the electron count...
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Corrosion degradation of spacers – examination of changes in bone cement coating.
PublikacjaSpacer is a special implant used at the time of infection after endoprosthetic surgery. It consists of a metal core and bone cement coating with an antibiotic. In the human body spacers are exposed to degradation processes. This paper looks at the effect of corrosion on spacers. Electrochemical corrosion tests were performer on titanium pins with bone cement coating in two solutions: Ringer’s solution and artificial...
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Expression of Deinococcus geothermalis Trehalose Synthase Gene in Escherichia coli and Its Enzymatic Properties
PublikacjaA novel trehalose synthase gene from Deinococcus geothermalis (DSMZ 11300) containing 1,692 bp reading-frame encoding 564 amino acids was amplified using PCR. The gene was ligated into pET30Ek/LIC vector and expressed after isopropyl alfa-D-thiogalactopyranoside induction in Escherichia coli BL21(DE3)pLysS. The recombinant trehalose synthase (DgeoTreS) containing a His6 tag at the C-terminus was purified by metal affinity chromatography...
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Linear and nonlinear impedance in iron oxide glasses containing alkaline ions and alkali free
PublikacjaThe linear and nonlinear impedance spectra of oxide glasses were measured in the frequency range of 1 mHz to 1 MHz and in the temperature range of 153K to 483K. Two groups of iron oxide glass samples were prepared, the first one containing alkaline ions and the second one without alkali. In the first group, compositions of glasses were as follows: (in %mol) 50% SiO2 , 25% PbO, 15% Fe2O3 and 15% one of alkaline oxides: Na2O, K2O,...
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Portable exhaled breath analyzer employing fluctuation-enhanced gas sensing method in resistive gas sensors
PublikacjaThis paper presents a portable exhaled breath analyser, developed to detect selected diseases. The set-up employs resistive gas sensors: commercial MEMS sensors and prototype gas sensors made of WO3 gas sensing layers doped with various metal ingredients. The set-up can modulate the gas sensors by applying UV light to induce physical changes of the gas sensing layers. The sensors are placed in a tiny gas chamber of a volume...
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Nanotubular Oxide Layer Formed on Helix Surfaces of Dental Screw Implants
PublikacjaSurface modification is used to extend the life of implants. To increase the corrosion resistance and improve the biocompatibility of metal implant materials, oxidation of the Ti-13Nb- 13Zr titanium alloy was used. The samples used for the research had the shape of a helix with a metric thread, with their geometry imitating a dental implant. The oxide layer was produced by a standard electrochemical method in an environment of...
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Mechanism of Li nucleation at graphite anodes and mitigation strategies
PublikacjaLithium metal plating is a critical safety issue in Li-ion cells with graphite anodes, and contributes significantly to ageing, drastically limiting the lifetime and inducing capacity loss. Nonetheless, the nucleation mechanism of metallic Li on graphite anodes is still poorly understood. But in-depth understanding is needed to rationally design mitigation measures. In this work, we conducted FirstPrinciples studies to elucidate...
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Free-standing TiO2 nanotubes decorated with spherical nickel nanoparticles as a cost-efficient electrocatalyst for oxygen evolution reaction
PublikacjaHere, we report significant activity towards the oxygen evolution reaction (OER) of spherical nickel nanoparticles (NPs) electrodeposited onto free-standing TiO2 nanotubes (TNT) via cyclic voltammetry. It has been shown that simple manipulation of processing parameters, including scan rate and number of cycles, allows for formation of the NPs in various diameters and amounts. The polarization data with respect to transmission electron...
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Zeolitic imidazolate framework (ZIF-8) modified cellulose acetate NF membranes for potential water treatment application
PublikacjaIn this study, cellulose acetate (CA)-based nanofiltration membranes, modified with zeolitic imidazole framework-8 (ZIF-8) particles, were prepared with various ZIF-8 contents (0, 0.1, 0.25, 0.5, 1 and 2 wt%), to obtain membranes with improved flux and filtration performance by combining advantages of CA polymer and ZIF-8 metal-organic frameworks. Removal efficiency studies were carried out with bovine serum albumin and two different...
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Educational and cognitive aspects of adaptation of nonuse spaces in monumental sacral objects.
PublikacjaThe area of attics and towers in historic churches in Europe are yet quite inaccessible places for visitors, shrouded in the atmosphere of mysticism, hiding many secrets. Introduction of the new public function into the non-used zones of the monumental sacral objects has many aspects including educational and cognitive ones which are discussed in the following article. The article indicates items that can be found in the zone above...
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Low-Cost Data-Driven Surrogate Modeling of Antenna Structures by Constrained Sampling
PublikacjaFull-wave electromagnetic (EM) analysis has become one of the major design tools for contemporary antenna structures. Although reliable, it is computationally expensive which makes automated simulation-driven antenna design (e.g., parametric optimization) difficult. This difficulty can be alleviated by utilization of fast and accurate replacement models (surrogates). Unfortunately, conventional data-driven modeling of antennas...
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Dynamics analysis of footbridge mode shapes the s8 expressway on the basis of the results of in situ tests
PublikacjaNon-destructive diagnostics for structure may use dynamic measurements realized during vibrations of a facility induced by dynamic environmental impact, enforced by the use of inductors or impulse impact. Dynamic tests and the analysis were undertaken for a footbridge situated over the expressway S8. The studies in situ allowed for dynamic characteristics to be determined: frequency, shape modes and damping for respective frequency...
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Computational Fluid Dynamics Simulation of Gas–Liquid Multiphase Flow in T-junction for CO2 Separation
PublikacjaThe article presents the results of a computational fluid dynamics (CFD) analysis of gas-liquid multiphase flow. The simulation was conducted using CFD code and the Euler–Euler approach. The presented study relates to the non–reactive, steady-state, turbulent flow of water and carbon dioxide mixture in a 3D pipe. Separation phenomenon between phases is observed. The solution was obtained using a mixture model. Different values...