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Wyniki wyszukiwania dla: gaussian beams
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Assessment of Wooden Beams from Historical Buildings Using Ultrasonic Transmission Tomography
PublikacjaThe main goal of this study was non-destructive evaluation of wooden elements using ultrasonic waves. The inspection was carried out on wooden beams from a historical object. Elastic wave signals were processed by ultrasonic transmission tomography to obtain imaging of the internal structure of tested elements without disturbing their state and integrity. The focus was on the influence of wood anisotropy on the propagation of ultrasonic...
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The method of analysis of damage reinforced concrete beams using terrestial laser scanning
PublikacjaThe authors present an analysis of the possibility to assess deformations and mechanisms of destructing bent reinforced concrete beams using the terrestrial laser scanning. As part of the experiments carried out at the Regional Laboratory of Construction of the Concrete Structures Division of the Civil and Environmental Engineering Faculty at Gdansk University of Technology, the reinforced concrete beams were subjected to destruction...
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Experimental Tests Of Sandwich Beams In The Design Process Of GFRP Shell Footbridge Structure
PublikacjaThe paper includes selected aspects of the study to elaborate architectural, material and construction design of pedestrian footbridge spans made of composite materials. The considered footbridge is a sandwich-type shell structure. The cooperation of PET foam core with outer lining surfaces is crucial for its load bearing capacity. The paper is aimed to experimental investigation of sandwich beams subjected to bending loading....
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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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SIMULATIONS OF FRACTURE IN CONCRETE BEAMS UNDER BENDING USING A CONTINUUM AND DISCRETE APPROACH
PublikacjaThe paper describes two-dimensional meso-scale results of fracture in notched concrete beams under bending. Concrete was modelled as a random heterogeneous 4-phase material composed of aggregate particles, cement matrix, interfacial transitional zones and air voids. Within continuum mechanics, the simulations were carried out with the finite element method based on a isotropic damage constitutive model enhanced by a characteristic...
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Experimental and numerical investigations on RC beams with stirrups scaled along height or length.
PublikacjaBelki żelbetowe (RC) ze zbrojeniem poprzecznym (strzemiona) poddane czteropunktowemu zginaniu zostały zbadane eksperymentalnie i numerycznie. Belki były skalowane wzdłuż wysokości lub długości. Były przezbrojone, aby uniknąć płynięcia zbrojenia podłużnego. W pierwszej kolejności przeprowadzono badania laboratoryjne na belkach żelbetowych ze strzemionami. Ze względu na brak podobieństwa geometrycznego zaobserwowano dwa odrębne tryby...
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Wave propagation in delaminated beam
PublikacjaW pracy przedstawiono model oraz wyniki analizy propagacji fali sprezystejw belce z delaminacją.
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Spectroscopic and microscopic study of Prussian blue film for electrochromic device application
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Russian companies on foreign stock markets: alternative to domestic market?
PublikacjaFirst aim of this study is to present the main aspects of the Russian stock market, including obstacles for local companies and investors. Second aim is presentation of the Russian companies listed on foreign stock exchanges. In order to perform such analysis, descriptive statistics and information about qualitative features were used. Assessment of the Russian stock market’s development level covered 2003-2012 time period. According...
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Debonding Size Estimation in Reinforced Concrete Beams Using Guided Wave-Based Method
PublikacjaThe following paper presents the results of the theoretical and experimental analysis of the influence of debonding size on guided wave propagation in reinforced concrete beams. The main aim of the paper is a development of a novel, baseline-free method for determining the total area of debonding between steel rebar embedded in a concrete cover on the basis of the average wave velocity or the time of flight. The correctness of...
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Verification of selected calculation methods regarding shear strength in beams without web reinforcement
PublikacjaThe purpose of the article was to compare selected calculation methods regarding shear strength in reinforced concrete beams without web reinforcement. Several calculation methods were tested. This included codes: PN-EN 1992-1-1:2008, ACI 318-14 and fib Model Code for Concrete Structures 2010. The analysis also consists of authorial methods published in technical literature. Calculations of shear strengths were made based on experimental...
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Fatigue Performance of Double-Layered Asphalt Concrete Beams Reinforced with New Type of Geocomposites
PublikacjaThe reinforcement of asphalt layers with geosynthetics has been used for several decades, but proper evaluation of the influence of these materials on pavement fatigue life is still a challenging task. The presented study investigates a novel approach to the reinforcement of asphalt layers using a new type of geogrid composite, in which square or hexagonal polypropylene stiff monolithic paving grid with integral junctions is bonded...
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Numerical studies on size effects in concrete beams. Architecture Civil Engineering Environment ACEE
PublikacjaW artykule przedstawiony wyniki obliczeń efektów skali w belkach betonowych podczas zginania. Zastosowano model sprężysto-plastyczny z nielokalnym osłabieniem. Rozkład wytrzymałości na rozciąganie był stochastyczny - przestrzennie skorelowany. Belki były geometrycznie podobne. Wyniki porównano z modelem efektu skali Bazanta.
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Conventional and advanced bending strength analysis of common and castellated, homogeneous and hybrid I-beams
PublikacjaAnaliza wytrzymałości na zginanie belek dwuteowych
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Application of continuous wavelet transform in vibration based damage detection method for beams and plates
PublikacjaW artykule zaprezentowano metodę lokalizacji uszkodzeń w konstrukcjach belkowych i płytowych bazującą na analizie falkowej. Wyznaczono postacie drgań badanych konstrukcji. Postacie drgań konstrukcji belkowej zostały przeanalizowane jednowymiarową transfrormatą falkową. Sformułowano dwuwymiarową transformatę falkową, którą zastosowano do postaci drgań konstrukcji płytowej.
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Application of continuous wavelet transform in vibration based damage detection method for beams and plates
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Three dimensional simulations of FRC beams and panels with explicit definition of fibres-concrete interaction
PublikacjaHigh performance concrete (HPC) is a quite novel material which has been rapidly developed in the last few decades. It exhibits superior mechanical properties and durability comparing to normal concrete. HPC can achieve also superior tensile performance if strong fibres (steel or carbon) are implemented in the matrix. Thus, there exist the unabated interest in studying how the addition of different types of fibres modifies the...
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Laboratory fatigue assessment of large geocomposite-reinforced double-layered asphalt concrete beams
PublikacjaGeosynthetic reinforcement of asphalt layers has been used for several decades. Evaluation of the influence of these materials on pavement fatigue life is still ongoing, especially for new types of geocomposites. This paper presents the evaluation of fatigue performance of large asphalt concrete beams reinforced with a new type of composite in which square or hexagonal polypropylene stiff monolithic paving grid with integral junctions...
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Using the ultrasonic tomography method to study the condition of wooden beams from historical buildngs
PublikacjaThe need to evaluate the integrity of wooden structural elements is constantly increasing. Non-destructive methods are becoming more popular in this field of research. One type of non-destructive testing is the ultrasonic imaging method, which allows the analysis of internal wood structures without disturbing their state and integrity. In this study, we are interested in assessing the effect of wood condition on the ultrasound...
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Coda wave interferometry in monitoring the fracture process of concrete beams under bending test
PublikacjaEarly detection of damage is necessary for the safe and reliable use of civil engineering structures made of concrete. Recently, the identification of micro-cracks in concrete has become an area of growing interest, especially using wave-based techniques. In this paper, a non-destructive testing approach for the characterization of the fracture process was presented. Experimental tests were made on concrete beams subjected to mechanical...
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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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Laboratory fatigue assessment of large geocomposite-reinforced double-layered asphalt concrete beams
PublikacjaGeosynthetic reinforcement of asphalt layers has been used for several decades. Evaluation of the influence of these materials on pavement fatigue life is still ongoing, especially for new types of geocomposites. This paper presents the evaluation of fatigue performance of large asphalt concrete beams reinforced with a new type of composite in which square or hexagonal polypropylene stiff monolithic paving grid with integral junctions...
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Application of twin-plane ECT sensor for identification of the internal imperfections inside concrete beams
PublikacjaThe main purpose of this paper is to investigate application of special construction of Electrical Capacitance Tomography (ECT) sensor to concrete beams internal homogeneity tests. Identification of internal imperfection inside the concrete beams is one of the main problems related to analysis of the construction structure bearing capacity. Therefore, this paper shows attempts to study the measurement prospects for this non-invasive,...
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Verification of Selected Calculation Methods Regarding Shear Strength in Reinforced and Prestressed Concrete Beams
PublikacjaThe purpose of this article was an attempt to compare selected calculation methods regarding shear strength in reinforced and prestressed concrete beams. Several calculation methods were tested. This included codes: PN-EN 1992-1-1:2008 [1], ACI 318- 14 [2] and fib Model Code for Concrete Structures 2010 [3]. The analysis also consists of methods published in technical literature. Calculations of shear strengths were made based...
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Thermal self-action effects for acoustic beams containing fronts in a Maxwell relaxing fluid
PublikacjaThis paper examines the thermal self-action of acoustic beams in a Maxwell relaxing fluid. This type of thermal self-action differs from that in a Newtonian fluid and behaves differently depending on a ratio of sound period and time of thermodynamic relaxation. The self-action which relates to sound beams containing shock fronts is also discussed. In addition, stationary and non-stationary types of self-action are considered.
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Numerical investigations of size effects in notched and un-notched concrete beams under bending
PublikacjaW artykule przedstawiono wyniki numerycznej analizy efektów skali (efektu deterministycznego i stochastycznego) w belkach betonowych z nacięciem i bez nacięcia poddanych zginaniu z uwzględnieniem lokalizacji odkształceń. Obliczenia wykonano przy zastosowaniu metody elementów skończonych i sprężysto-plastycznego modelu z nielokalnym osłabieniem. Pokazano wpływ wielkości belek betonowych na ich nośność oraz rozkład lokalizacji odkształceń.
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Experimental and numerical investigations of size effects in reinforced concrete beams with steel or basalt bars.
PublikacjaW artykule przedstawiono wyniki obliczeń efektów skali w belkach betonowych zbrojonych prętami stalowymi i bazaltowymi podczas zginania. Zastosowano model sprężysto-plastyczny z nielokalnym osłabieniem. Rozkład wytrzymałości na rozciąganie był stochastyczny – przestrzennie skorelowany. Belki były geometrycznie podobne. Wyniki porównano z modelem efektu skali Bazanta
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Photocatalytic activity of TiO2 immobilized on glass beads
PublikacjaAktywność fotokatalityczną czystego TiO2 oraz TiO2 modyfikowanego borem zbadano w reakcji degradacji wodnego roztworu fenolu. TiO2 osadzono na szklanych kulkach i umieszczono w reaktorze wyposażonym w szklaną, kwarcową rurę, którą naświetlano promieniowaniem z zakresu UV-Vus
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Managing Virtual Teams: The Three Dimensions Scope
PublikacjaDue to globalisation and economic reasons the number of people working as a team in a virtual environment is increasing. Although virtual team can outperform teams working in a traditional environment still many managers face difficulties in achieving this goal. This article describes the idea of a system that would support knowledge management in virtual teams focusing on three dimensions of virtual work: location, organisation,...
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Attributes of Entrepreneurial Teams as Elements of a Mental Model
PublikacjaAn entrepreneurial team can be defined as a small group of individuals holding ownership or control positions who create or develop an entrepreneurial venture and have shared commitments towards each other. Entrepreneurial teams start numerous new ventures or affect the performance of firms due to their social capital based on some characteristic attributes. The mental models of teams refer to internal, organised representation...
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Effect of Electron Beam Power Density on the Structure of Titanium Under Non-Vacuum Electron-Beam Treatment
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Acoustic Streaming Induced by Periodic and Aperiodic Sound in a Bubbly Liquid
PublikacjaThe vortex ow which follows intense sound propagating in a bubbly liquid, is considered. The reasons for acoustic streaming are both nonlinearity and dispersion. That makes streaming especial as compared with that in a Newtonian uid. Conclusions concern the vortex ow induced in a half-space by initially harmonic or impulse Gaussian beam. The vortex ow recalls a turbulent ow with increasing in time number of small-scale vortices...
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Enriched buckling for beam-lattice metamaterials
PublikacjaWe discuss two examples of beam-lattice metamaterials which show attractive mechanical properties concerning their enriched buckling. The first one considers pantographic beams and the nonlinear solution is traced out numerically on the base of a Hencky’s model and an algorithm based on Riks’ arc-length scheme. The second one concerns a beam-lattice with sliders and the nonlinear solution is discussed in analytic way and, finally,...
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Beam Quality of Multicore Fibre Lasers
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Distorsional analysis of I-section beam
PublikacjaAn elastic stiffness matrix was derived in the case of distortion of a restrained thin-walled I-section beam using the minimum total stationary elastic energy condition. The function describing the angle of distortion was adopted form the solution of differential equation in the case of restrained distortion. The example presented in the paper helps to assess the correctness of the proposed solution. The proposed elastic stiffness...
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SIMPLIFIED DYNAMIC MODEL OF ROTATING BEAM
PublikacjaIn the paper a hybrid model of rotating beam is presented. It was obtained by using two methods: modal decomposition and spatial discretization. Reduced modal model was built for the system without the load related to inertia forces that occur during beam rotation. This inertia load was next modeled by using the method of simply spatial discretization and combined with reduced modal model. This approach allows to obtain accurate...
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Organic-inorganic composites consisted of poly(3,4-ethylenedioxythiophene)and Prussian Blue analogues
PublikacjaThe organic-inorganic material consisted of poly(3,4-ethylenedioxythiophene) (pEDOT) and copper hexacyanoferrate (Cuhcf) was synthesized. The pEDOT film with Fe(CN)63−/4− as counter-ions potentiodynamically polarized in aqueous CuCl2 electrolyte brings about stable hybrid material (pEDOT/Cuhcf) performing single redox activity of FeII/III at a formal potential Ef = 0.61 V (vs. Ag/AgCl/0.1 M KCl) and less clearly shaped two redox...
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Цифровая репрезентация лексем русского языка [Digital representation of Russian lexemes]
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Омонимия сокращений в русском языке [The homonymy of abbreviations in the Russian language]
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Performance of CMS hadron calorimeter timing and synchronization using test beam, cosmic ray, and LHC beam data
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Size effect in concrete beams under bending – influence of the boundary layer and the numerical description of cracks
PublikacjaIn the paper the size effect phenomenon in concrete is analysed. The results of numerical simulations of using FEM on geometrically similar un-notched and notched concrete beams under bending are presented. Concrete beams of four different sizes and five different notch heights under three-point bending test were simulated. In total 18 beams were analysed. Two approaches were used to describe cracks in concrete. First, eXtended...
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Reference-free determination of debonding length in reinforced concrete beams using guided wave propagation
PublikacjaThis paper presents theoretical and experimental investigations of guided wave propagation in reinforced concrete beams, with pre-existing debonding between steel rebars and concrete blocks, for the purpose of damage detection. The primary aim of these investigations was a detailed analysis of the possible applications of wave propagation in single and multiple debonding detection in reinforced concrete structures and reference-free...
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Experimental study of shear strength and failure mechanisms in RC beams scaled along height or length
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Performance of the CMS Level-1 trigger during commissioning with cosmic ray muons and LHC beams
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The vibration-based assessment of the influence of elevated temperature on the condition of concrete beams with pultruded GFRP reinforcement
PublikacjaConcrete beams reinforced with glass fiber reinforced polymer (GFRP) bars subjected to elevated temperature have been experimentally studied. The influence of high temperatures on GFRP-reinforced concrete beams condition has been check both, destructively and nondestructively. The nondestructive tests foresaw vibration-based tests to obtain the natural frequency values after exposure to varying temperatures. The vibration-based...
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SFEM Analysis of Beams with Scaled Lengths including Spatially Varying and Cross-Correlated Concrete Properties
PublikacjaThis paper presents the results obtained for plain concrete beams under four-point bending with spatially varying material properties. Beams of increasing length but constant depth were analyzed using the stochastic finite element method. Spatial fluctuation of a uniaxial tensile strength, fracture energy and elastic modulus was defined within cross-correlated random fields. The symmetrical Gauss probability distribution function...
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Modelling and parameter identification of steel–concrete composite beams in 3D rigid finite element method
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Failure characterisation of sandwich beams using integrated acoustic emission and digital image correlation techniques
PublikacjaThe paper presents the experimental study of the failure behaviour of sandwich beams subjected to bending. The samples examined are sandwich beams made of polyethylene terephthalate foam core and glass fibre-reinforced polymer laminate face sheets. In a series of experiments, it has been proposed to integrate diagnostic techniques with acoustic emission and digital image correlation to accurately track the cracking process on the...
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Three-point bending test of sandwich beams supporting the GFRP footbridge design process - validation
PublikacjaSome selected aspects concerning material and construction design issues for pedestrian footbridge made of GFRP composite materials are elaborated in this paper. The analysis is focused on validation tests, which are particularly important because of the advanced technology and materials that are used for this innovative bridge. The considered footbridge is a sandwich-type shell structure comprising of PET foam core and outer skins...
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NON-STATIONARY THERMAL SELF-ACTION OF ACOUSTIC BEAMS CONTAINING SHOCK FRONTS IN THERMOCONDUCTING FLUID
PublikacjaNon-stationary thermal self-action of a periodic or impulse acoustic beam containing shock fronts in a thermoconducting Newtonian fluid is studied. Self-focusing of a saw-tooth periodic and impulse sound is considered, as well as that of a solitary shock wave which propagates with the linear sound speed. The governing equations of the beam radius are derived. Numerical simulations reveal that the thermal conductivity weakens the...