Filtry
wszystkich: 753
wybranych: 662
Wyniki wyszukiwania dla: ISOTROPIC COMPRESSION
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Quasi-exact solutions for two interacting electrons in two-dimensional anisotropic dots
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Numerical analysis of a test embankment on soft ground using an anisotropic model with destructuration
PublikacjaPrzeprowadzono analizę numeryczną konsolidacji podłoża słabonośnego pod obciążeniem próbnego nasypu drogowego metodą elementów skończonych. Zachowanie się gruntu słabonośnego zamodelowano przy użyciu nowego modelu konstytutywnego typu multi-laminate uwzględniającego anizotropię wytrzymałości oraz zjawisko destrukturyzacji. Wyniki obliczeń porównano z pomiarami polowymi.
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Non-Linear Interaction of Harmonic Waves in a Quasi-Isentropic Flow of Magnetic Gas
PublikacjaThe diversity of wave modes in the magnetic gas gives rise to a wide variety of nonlinear phenomenaassociated with these modes. We focus on the planar fast and slow magnetosound waves in the geometryof a flow where the wave vector forms an arbitrary angleθwith the equilibrium straight magnetic field.Nonlinear distortions of a modulated signal in the magnetic gas are considered and compared to thatin unmagnetised gas. The case of...
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Modelling tunnelling-induced deformation in stiff soils with a hyperelastic–plastic anisotropic model
PublikacjaIn this paper, the tunnelling-induced deformation in anisotropic stiff soils is analysed using FE modelling. The influence of material description is investigated rather than an advanced simulation of the tunnelling method. A new hyperelastic– plastic model is proposed to describe the anisotropic mechanical behaviour of stiff highly overconsolidated soil. This model can reproduce the superposition of variable stress-induced anisotropy...
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A general theory for anisotropic Kirchhoff–Love shells with in-plane bending of embedded fibers
PublikacjaThis work presents a generalized Kirchhoff–Love shell theory that can explicitly capture fiber-induced anisotropy not only in stretching and out-of-plane bending, but also in in-plane bending. This setup is particularly suitable for heterogeneous and fibrous materials such as textiles, biomaterials, composites and pantographic structures. The presented theory is a direct extension of classical Kirchhoff–Love shell theory to incorporate...
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Propagation of initially sawtooth periodic and impulsive signals in a quasi-isentropic magnetic gas
PublikacjaThe characteristics of propagation of sawtooth periodic and impulsive signals at a transducer are analytically studied in this work. A plasma under consideration is motionless and uniform at equilibrium, and its perturbations are described by a system of ideal magnetohydrodynamic equations. Some generic heating/cooling function, which in turn depends on equilibrium thermodynamic parameters, may destroy adiabaticity of a flow and...
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Nonlinear Excitation of the Non-Wave Perturbations by the Magnetoacoustic Waves in the Non-Isentropic Plasma
PublikacjaNonlinear excitation of slow modes by the planar magnetosonic perturbations in a plasma is discussed. Plasma is an open system due to radiation and external heating. This may stipulate enhancement of wave perturbations and hence the acoustical activity of plasma. Plasma is assumed to be a homogeneous ideal gas with infinite electrical conductivity. The straight magnetic field is orthogonal to the velocity of fluid’s...
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Influence of anisotropic stiffness in numerical analyses of tunneling and excavation problems in stiff soils
PublikacjaIn the stiff overconsolidated soil deposits anisotropy influences small and intermediate strain stiffness and hence it has important impact on the results of discplacement preditcions in soil-structure modelling. The authors developed a cross-anisotropic soil model which combines both stress dependent and micro-structural anisotropy. The model is based on the anisotropic hyperelastic kernel for small strain stiffness. Reference...
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Solvation of multivalent cations in methanol - apparent molar volumes, expansibilities, and isentropic compressibilities
PublikacjaWyznaczono gęstości roztworów trifluorometanosulfonianów galu, itru, lantanu, gadolinu i lutetu w metanolu w zakresie temperatur (283.15 to 313.15) K. Zmierzono prędkości dźwięku dla tych układów w temperaturze T = 298.15 K. Z uzyskanych danych wyznaczono standardowe cząstkowe objętości molowe i ich pochodne temperaturowe oraz standardowe cząstkowe molowe ściśliwości adiabatyczne badanych jonów. Wyniki omówiono stosując klasyczny...
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FE-studies on shear localization in an anisotropic micro-polar hypoplastic granular material
PublikacjaW artykule przedstawiono wyniki numerycznej wpływu anizotropii w materiałach granulowanych na powstawanie lokalizacji odkształceń. Obliczenia wykonano dla ściskania dwuosiowego stosując metodę elementów skończonych na bazie mikropolarnego prawa hipoplastycznego.
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Investigations of shear localization in granular bodies within an anisotropic micro-polar hypoplasticity
PublikacjaArtykuł omawia wyniki MES dotyczące stref lokalizacji w materiałach granulowanych podczas ściskania w płaskim stanie odkształcenia. Obliczenia wykonano na bazie mikro-polarnego prawa hipoplastycznego. W obliczeniach uwzględniono anizotrpowość ośrodka w skutek sedymentacji. Analizę wykonano dla różnych kątów napełnienia materiału w stosunku do płaszczyzny obciążenia.
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On well-posedness of the first boundary-value problem within linear isotropic Toupin–Mindlin strain gradient elasticity and constraints for elastic moduli
PublikacjaWithin the linear Toupin–Mindlin strain gradient elasticity we discuss the well-posedness of the first boundary-value problem, that is, a boundary-value problem with Dirichlet-type boundary conditions on the whole boundary. For an isotropic material we formulate the necessary and sufficient conditions which guarantee existence and uniqueness of a weak solution. These conditions include strong ellipticity written in terms of higher-order...
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2D inverse solution for cone-shaped centrifugal compressor
PublikacjaWprowadzono stożkowy układ współrzędnych dla opisania obszaru wirnika sprężarki promieniowej. W takim układzie został sformułowany problem odwrotny. Oznacza to, że dla założonej jednej rodziny powierzchni prądu (S1) w formie powierzchni stożkowych druga rodzina (S2) jest znajdywana w drodze rozwiązania układu równań zachowania. Pokazano w jaki sposób rozwiązanie zależy od warunków brzegowych. Przedstawiona metoda jest przydatna...
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The influence of compressive gear on maximal load lifted in competitive powerlifting.
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Compressive Sensing Approach to Harmonics Detection in the Ship Electrical Network
PublikacjaThe contribution of this paper is to show the opportunities for using the compressive sensing (CS) technique for detecting harmonics in a frequency sparse signal. The signal in a ship’s electrical network, polluted by harmonic distortions, can be modeled as a superposition of a small number of sinusoids and the discrete Fourier transform (DFT) basis forms its sparse domain. According to the theory of CS, a signal may be reconstructed...
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Reliability of Corroded Stiffened Plate Subjected to Uniaxial Compressive Loading
PublikacjaThe work is focused on the reliability of corroded stiffened plates subjected to compressive uniaxial load based on the progressive collapse approach as stipulated by the Common Structural Rules for Bulk Carriers and Oil Tankers, employing the limit state design. Two different cases have been investigated. In the first model, the corrosion degradation led to uniform thickness loss, whereas the mechanical properties were unchanged,...
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FE analysis of support-specimen interaction of compressive experimental test
PublikacjaThe objective of this work is to investigate the support-specimen interaction during the compressive experimental testing of stiffened plates. The interaction is analyzed employing the nonlinear Finite Element Method using the commercial software ANSYS. The connection between the stiffened plate and testing supports is modelled with the use of contact elements, where several possible interaction scenarios are investigated, and...
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New devices to capture the temperature effect under dynamic compression and impact perforation of polymers, application to PMMA
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Analytical predictions for the buckling of a nanoplate subjected to non-uniform compression based on the four-variable plate theory
PublikacjaIn the present study, the buckling analysis of the rectangular nanoplate under biaxial non-uniform compression using the modified couple stress continuum theory with various boundary conditions has been considered. The simplified first order shear deformation theory (S-FSDT) has been employed and the governing differential equations have been obtained using the Hamilton’s principle. An analytical approach has been applied to obtain...
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The effect of preliminary creep-strain on material behavior under LCF tension/compression and pure torsion regimes
PublikacjaThis paper presents the results of experimental tests of monotonic tension and torsion, creep-rupture and preliminary creep at 200C and 300C, as well as low-cycle fatigue of 2024 T3511 aluminum alloy. The fatigue process was conducted at room temperature for uniaxial tension/compression and torsion. The as-received material and pre-deformed material were also investigated during creep at elevated temperature. Basic monotonic,...
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Experimental and numerical evaluation of mechanical behaviour of composite structural insulated wall panels under edgewise compression
PublikacjaA composite structural insulated sandwich panel (CSIP) is a quite novel approach to the idea of sandwich structures. A series of natural-scale experimental test is required each time a change in panel’s geometry is planned and a reliable computational tool is required to precede actual laboratory testing with virtual simulations. An attempt of creating such a tool has been made with use of a commercial FEM code ABAQUS, in order...
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Computations of size effects in granular bodies within micro-polar hypoplasticity during plane strain compression.
PublikacjaArtykuł omawia deterministyczny i statystyczny efekt skali w materiałach granulowanych podczas sciskania w płaskim stanie odkształcenia. Obliczenia wykonano metodą elementów skończonych na bazie mikropolarnego prawa hipoplastycznego. Wykorzystano metodę hiperłacińskiego próbkowania.
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DEM investigations of two-dimensional granular vortex- and anti-vortex- structures during plane strain compression.
PublikacjaDEM investigations of two-dimensional granular vortex- and anti-vortex- structures during plane strain compression.
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The anisotropic photorefractive effect in lithium sulfo-phosphate glass system doped with nickel ions
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Ground-state correlation properties of charged bosons trapped in strongly anisotropic harmonic potentials
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Lyotropic liquid crystal based on zinc oxide nanoparticles obtained by microwave solvothermal synthesis
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Anisotropic stochastic dispersion model for large-eddy simulations of particle-laden turbulent flows
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Spectral criterion for high-cycle fatigue of anisotropic metals under multiaxial random loads
PublikacjaPraca dotyczy oceny ograniczonej trwałości zmęczeniowej metali ciągliwych, poddanych wieloosiowym obciążeniom statycznym i dynamicznym. Zakłada się, że kartezjańskie składowe tensora naprężenia są sumą losowych wartości średnich o znanych drugich momentach statystycznych i stacjonarnych procesów stochastycznych o znanych gęstościach widmowych mocy. Przyjmując, że procesy te są stacjonarnie skorelowane, różniczkowalne w sensie średnio-kwadratowym...
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High-cycle fatique criterion for anisotropic metals under multiaxial constant and periodic loads
PublikacjaPrzedmiotem rozważań jest okresowe naprężenie, którego kartezjańskie składowe są dane w postaci szeregów Fouriera. Dla uwzględnienia wpływu składowych stałych zastosowano zmodyfikowaną formułę Soderberga. Zdefiniowano naprężenie równoważne o synchronicznych składowych i sformułowano kryterium ograniczonej trwałości zmęczeniowej. Kryterium to obejmuje warunki wytrzymałości statycznej i bezpieczeństwa zmęczeniowego z zakresie wysokocyklowym...
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Magnetoacoustic Heating of Plasma Caused by Periodic MagnetosoundPerturbations with Discontinuities in a Quasi-Isentropic Magnetic Gas
PublikacjaThe magnetoacoustic heating of plasma by harmonic or periodic saw-tooth perturbations at a trans-ducer is theoretically studied. The planar fast and slow magnetosound waves are considered. The wavevector may form an arbitrary angleθwith the equilibrium straight magnetic field. In view of variableθand plasma-β, the description of magnetosound perturbations and appropriate magnetosound heatingis fairly difficult. The scenario of...
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On the Fenchel–Moreau conjugate of G-function and the second derivative of the modular in anisotropic Orlicz spaces
PublikacjaIn this paper, we investigate the properties of the Fenchel–Moreau conjugate of G-function with respect to the coupling function c(x, A) = |A[x]2 |. We provide conditions that guarantee that the conjugate is also a G-function. We also show that if a G-function G is twice differentiable and its second derivative belongs to the Orlicz space generated by the Fenchel–Moreau conjugate of G then the modular generated by G is twice differentiable...
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On Anti-Plane Surface Waves Considering Highly Anisotropic Surface Elasticity Constitutive Relations
PublikacjaWithin the framework of highly anisotropic surface elasticity model we discuss the propagation of new type of surface waves that are anti-plane surface waves. By the highly anisotropic surface elasticity model we mean the model with a surface strain energy density which depends on incomplete set of second derivatives of displacements. From the physical point of view this model corresponds to a coating made of a family of parallel...
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Anisotropic mechanical behavior and auxeticity of penta-graphene: Molecular statics/molecular dynamics studies
PublikacjaWe investigate the mechanical properties of penta-graphene (PG), a recently proposed two-dimensional carbon allotrope using atomistic simulation techniques combined with the empirical description of interatomic interactions. We report on the dependence of its three in-plane mechanical moduli (i.e. Young's modulus, Poisson's ratio and shear modulus) on the deformation direction, strain and temperature. We show that PG displays a...
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Inverse method for 3D shaped centrifugal compressor (rotor and diffuser)
PublikacjaW artykule przedstawiono sposób wyznaczania kształtu wirnika i dyfuzora sprężarki promieniowej. Podano układ równań oraz warunki zamknięcia układu. Przykładowe rozwiązanie wskazuje na silny wpływ warunków na wlocie na kształt dyfuzora.
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Experimental and numerical identification of separation zones in the cent-rifugal compressor
PublikacjaW pracy przedstawiono analizę przepływu w obszarze koła wirnikowego oraz dyfuzora bezłopatkowego sprężarki powietrza. Wyniki obliczeń w ramach modelu 3D (FLUENT 5.5) porównano z wynikami badań laboratoryjnych na stanowisku sprężarkowym Katedry Sprężarek w Sankt Petersburgu. Celem porównania jest ocena możliwości identyfikacji stref przepływu z oderwaniem, w ramach modeli dostępnych w wykorzystanym programie obliczeniowym. W wyniku...
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An Investigation into Cold Start Emissions from Compression Ignition Engines using EU Legislative Emissions Test Procedures
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Experimental investigation and optimization of compression moulding parameters for MWCNT/glass/kevlar/epoxy composites on mechanical and tribological properties
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The Acute Effects of External Compression With Blood Flow Restriction on Maximal Strength and Strength-Endurance Performance of the Upper Limbs
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Analysis of impact of lossy audio compression on the robustness of watermark embedded in the DWT domain for non-blind copyright protection
PublikacjaA methodology of non-blind watermarking of the audio content is proposed. The outline of audio copyright problem and motivation for practical applications are discussed. The algorithmic theory pertaining watermarking techniques is briefly introduced. The system architecture together with employed workflows for embedding and extracting the watermarks are described. The implemented approach is described and obtained results are reported....
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Discrete element method simulations of fracture in concrete under uniaxial compression based on its real internal structure
PublikacjaThe paper describes experimental and numerical results of concrete fracture under quasi-static uniaxial compression. Experimental uniaxial compression tests were performed on concrete cubic specimens. Fracture in concrete was detected at the aggregate level by means of three non-destructive methods: three-dimensional X-ray microcomputed tomography, two-dimensional scanning electron microscope and manual two-dimensional digital...
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Analysis of ultimate compressive strength of cracked plates with the use of DOE techniques
PublikacjaThe objective of this work is to investigate the structural compressive response of plates with locked cracks accounting for all relevant factors and correlation between them. The nonlinear FE model considering both geometric and material nonlinearities is employed herein, and the FE model of the structural response of intact plates is validated with the available experimental data. In the common studies, based on One Factor at...
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Signal Reconstruction from Sparse Measurements Using Compressive Sensing Technique
PublikacjaThe paper presents the possibility of applying a new class ofmathematical methods, known as Compressive Sensing (CS) for recovering thesignal from a small set of measured samples. CS allows the faithful recon-struction of the original signal back from fewer random measurements bymaking use of some non-linear reconstruction techniques. Since of all thesefeatures, CSfinds its applications especially in the areas where, sensing is...
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On the origin of surface imposed anisotropic growth of salicylic and acetylsalicylic acids crystals during droplet evaporation
PublikacjaIn this paper droplet evaporative crystallization of salicylic acid (SA) and acetylsalicylic acid (ASA) crystals on different surfaces, such as glass, polyvinyl alcohol (PVA), and paraffin was studied. The obtained crystals were analyzed using powder X-ray diffraction (PXRD) technique. In order to better understand the effect of the surface on evaporative crystallization, crystals deposited on glass were scraped off. Moreover,...
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Peculiar hydrogen bonding behaviour of water molecules inside the aqueous nanochannels of lyotropic liquid crystals
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On description of periodic magnetosonic perturbations in a quasi-isentropic plasma with mechanical and thermal losses and electrical resistivity
PublikacjaMagnetosonic periodic perturbations in a uniform and infinite plasma model are considered. Damping due to compressional viscosity, electrical resistivity, and thermal conduction are taken into account, as well as some heating–cooling function, which may destroy the isentropicity of wave perturbations. The wave vector forms arbitrary angle h with the equilibrium straight magnetic field, and all perturbations are functions...
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Mountain pass type periodic solutions for Euler–Lagrange equations in anisotropic Orlicz–Sobolev space
PublikacjaUsing the Mountain Pass Theorem, we establish the existence of periodic solution for Euler–Lagrange equation. Lagrangian consists of kinetic part (an anisotropic G-function), potential part and a forcing term. We consider two situations: G satisfying at infinity and globally. We give conditions on the growth of the potential near zero for both situations.
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Dynamic analysis of the first stage compressor bladed disc of an aircraft engine
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HEALTH MONITORING OF A COMPRESSION IGNITION ENGINE FED WITH DIFFERENT LOW-SULPHUR MARINE FUELS BY ENDOSCOPIC IMAGE PROCESSING AND ANALYSIS
PublikacjaThis article characterises the methodology for the endoscopic testing of a laboratory diesel engine used for testing marine fuels. The ‘Shadow’ measurement method used in the XLG3 type EVEREST digital endoscope, for quantitative and qualitative identification of detected surface defects, was approximated. Representative endoscopic images of the elements limiting the working space of the research engine are demonstrated, having...
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Effect of free water on the quasi‑static compression behavior of partially‑saturated concrete with a fully coupled DEM/CFD approach.
PublikacjaThe work aims to numerically investigate the quasi-static response of partially fluid-saturated concrete under two-dimensional uniaxial compression at the mesoscale. We investigated how the impact of free pore fluid content (water and gas) affected the quasi-static strength of concrete. The totally and partially fluid-saturated concrete behavior was simulated using an improved pore-scale hydro-mechanical model based on DEM/CFD....
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Advanced numerical modelling for predicting residual compressive strength of corroded stiffened plates
PublikacjaAn advanced methodology for predicting the residual compressive strength of corroded stiffened plates is developed here using the non-linear finite element method. The non-uniform loss of a plate thickness is accounted for on a macro-scale. In contrast, mechanical properties are changed using the constitutive model to reflect the corrosion degradation impact on a micro-scale. Three different stiffened plate thicknesses are considered,...