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Wyniki wyszukiwania dla: KINETIC CONSTITUTIVE EQUATIONS
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The Suzuki model of the multipath fading channel
Dane BadawczeThe dataset contains the results of simulations that are part of the research on modelling the multipath fading in the communication channel. The Suzuki fading envelope is generated using the Monte-Carlo simulation (MCS) in the LabVIEW programming environment.
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Novel Analytic-Numerical Model of Free Convection: with Leading Edge Considered
PublikacjaA novel solution of the free convection boundary problem is represented in analytical form for velocity and temperature for an isothermal vertical plate, as an example. These fields are built as a Taylor Series in the x coordinate with coefficients as functions of the vertical coordinate (y). We restrict ourselves by cubic approximation for both functions. The basic Navier-Stokes and Fourier-Kirchhoff equations and boundary conditions...
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Maximum transportation growth in energy and solute particles in Prandtl martial across a vertical 3D-heated surface: Simulations achieved using by finite element approach
PublikacjaThe goal of this study is to determine the maximum energy and solute particles' transportation growth in a 3D-heated region of Prandtl martial through a dynamic magnetic field. The effects of this field on the properties of solvent molecules and heat conduction are studied. A correctly stated functional method and a finite element approach are comparable to a certain type of differential equations. In order demonstrate the effects...
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Effect of Sinusoidal Corrugated Geometries on the Vibrational Response of Viscoelastic Nanoplates
PublikacjaThe vibrational behavior of viscoelastic nanoplates with a corrugated geometry is a key topic of practical interest. This problem is addressed here for wrinkled nanoplates with small corrugations related to incorrect manufacturing. To this end, a new One-Variable First-order Shear Deformation plate Theory (OVFSDT) is proposed in a combined form with a non-local strain gradient theory. The Kelvin–Voigt model is employed to describe...
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Stability by linear approximation for time scale dynamical systems
PublikacjaWe study systems on time scales that are generalizations of classical differential or difference equations and appear in numerical methods. In this paper we consider linear systems and their small nonlinear perturbations. In terms of time scales and of eigenvalues of matrices we formulate conditions, sufficient for stability by linear approximation. For non-periodic time scales we use techniques of central upper Lyapunov exponents...
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Simulation of the remanence influence on the transient states in a single-phase multiwinding transformer
PublikacjaThis paper presents the mathematical model of a single-phase multi-winding core type transformer taking into account magnetic hysteresis phenomenon based on the feedback Preisach model (FPM). The set of loop differential equations was developed for a K-th winding transformer model where the flux linkages of each winding includes flux Φ common to all windings as a function of magneto motive force Θ of all windings. The first purpose...
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Vibration and buckling characteristics of nonlocal beam placed in a magnetic field embedded in Winkler–Pasternak elastic foundation using a new refined beam theory: an analytical approach
PublikacjaIn this article, a new refined beam theory, namely one variable first-order shear deformation theory, has been employed to study the vibration and buckling characteristics of nonlocal beam. The beam is exposed to an axial magnetic field and embedded in Winkler–Pasternak foundation. The von Kármán hypothesis along with Hamilton’s principle has been implemented to derive the governing equations for both the vibration and buckling...
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Finite element modeling of plastic hinges based on ductility demand-capacity method using nonlinear material for dynamic analysis
PublikacjaThe article discusses modeling plastic hinges in reinforced concrete interme-diate supports using finite elements methods. The ductility demand-capacitymethod was used to determine the geometrical parameters of cross-section plas-ticization zones, their ability to move and rotate, as well as their ductility. Dueto the varied geometry and stiffness of the supports and their nonlinear behav-ior under dynamic load, this method was...
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On the Nonlinear Effects of Magnetoacoustic Perturbations in Optically Thin Quasi-Isentropic Plasmas
PublikacjaNonlinear effects of planar magnetosound perturbations in a plasma are discussed. Plasma is non-adiabatic due to optically thin radiation and external heating. For these reasons, thermal instability of a plasma may appear which makes it acoustically active. The plasma is assumed to be initially homogeneous ideal gas with infinite electrical conductivity permeated by a straight magnetic field which is orthogonal to the trajectories...
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Robust identification of quadrocopter model for control purposes
PublikacjaThe paper addresses a problem of quadrotor unmanned aerial vehicle (so-called X4-flyer or quadrocopter) utility model identification for control design purposes. To that goal the quadrotor model is assumed to be composed of two abstracted subsystems, namely a rigid body (plant) and four motors equipped with blades (actuators). The model of the former is acquired based on a well-established dynamic equations of motion while the...
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FEM modelling of screw displacement pile interaction with subsoil
PublikacjaPredicting the-settlement characteristics of piles is an important element in the designing of pile foundations. The most reliable method in evaluating pile-soil interaction is the static load test, preferably performed with instrumentation for measuring shaft and pile base resistances. This, however, is a mostly post-implementation test. In the design phase, prediction methods are needed, in which numerical simulations play an...
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Molecular basis of essentiality of early critical steps in the lipopolysaccharide biogenesis in Escherichia coli K-12: requirement of MsbA, cardiolipin, LpxL, LpxM and GcvB
PublikacjaTo identify the physiological factors that limit the growth of Escherichia coli K-12 strains synthesizing minimal lipopolysaccharide (LPS), we describe the first construction of strains devoid of the entire waa locus and concomitantly lacking all three acyltransferases (LpxL/LpxM/LpxP), synthesizing minimal lipid IVA derivatives with a restricted ability to grow at around 21 °C. Suppressors restoring growth up to 37 °C of Δ(gmhD-waaA)...
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A New Expression System Based on Psychrotolerant Debaryomyces macquariensis Yeast and Its Application to the Production of Cold-Active β-D-Galactosidase from Paracoccus sp. 32d
PublikacjaYeasts provide attractive host/vector systems for heterologous gene expression. The currently used yeast-based expression platforms include mesophilic and thermotolerant species. A eukaryotic expression system working at low temperatures could be particularly useful for the production of thermolabile proteins and proteins that tend to form insoluble aggregates. For this purpose, an expression system based on an Antarctic psychrotolerant...
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Kształtowanie toru zwrotnego rozjazdu z odcinkami krzywizny liniowej
PublikacjaW pracy została przedstawiona analityczna metoda kształtowania toru zwrotnego rozjazdu kolejowego posiadającego na swojej długości odcinki krzywizny liniowej. Odróżnia go to w istotny sposób od rozwiązania typowego, stanowiącego pojedynczy łuk kołowy bez krzywych przejściowych. W metodzie tej dokonano identyfikacji problemu rozkładu krzywizny za pomocą równań różniczkowych. Uzyskane rozwiązania mają charakter uniwersalny; m. in....
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Combining Computational Fluid Dynamics with a Biokinetic Model for Predicting Ammonia and Phosphate Behavior in Aeration Tanks
PublikacjaThe aim of this study was to use computational fluid dynamics for predicting the behavior of reactive pollutants (ammonia and phosphate) in the aerobic zone of the bioreactor located at the Wschod wastewater treatment plant in Gdansk, Poland. The one-dimensional advection-dispersion equation was combined with simple biokinetic models incorporating the Monod-type expressions as source terms for the two pollutants. The problem was...
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Preliminary Testing of the Influence of Modified Polycaprolactones on Anabaena Variabilis Growth in Seawater
PublikacjaSeveral new biodegradable polymer materials have recently come onto the global market. Mostly the results on degradation kinetic studies are presented. This paper suggests using one of the tests to estimate the impact of polymer packaging material on sea life. The microorganism chosen was Anabaena variabilis (identified in many waters, including those of the Baltic Sea, especially in the Gulf of Gdansk and Puck Bay; this cyanobacterium...
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Fuzzy Control of Waves Generation in a Towing Tank
PublikacjaThis paper presents the results of research related to the transformation of electrical energy into potential and kinetic energy of waves generated on the water surface. The waves are generated to model the environmental conditions for the needs of the model tests. The model tests are performed on model-scale objects to predict the features of full-scale maritime objects. It is done to improve human safety and the survivability...
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A comparative study on the decolorization of Tartrazine, Ponceau 4R, and Coomassie Brilliant Blue using persulfate and hydrogen peroxide based Advanced Oxidation Processes combined with Hydrodynamic Cavitation
PublikacjaDecolorization of Ponceau 4R, Tartrazine, and Coomassie Brilliant Blue (CBB) was studied using hybrid processes of hydrodynamic cavitation (HC) with potassium persulfate (KPS) and hydrogen peroxide (H2O2). The different properties of these dyes such as hydrophobicity, molecular structures, and molecular weights provided this opportunity to investigate the effects of these factors by comparing the decolorization values of the dyes....
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Interactions of telomeric proteins with nucleic acids: sequence recognition on intact and oxidatively damaged telomeres
PublikacjaTelomeres are complex nucleoprotein assemblies that play a vital role in the maintenance of functional ends of linear chromosomes. Telomeric DNA, composed of tandem repeats of the 5'-TTAGGG-3' motif, solves the so-called end replication problem: as chromosomes shorten with each cell division, no information is lost, and the telomere can be re-extended. In the cell, many protein factors regulate telomere length, nuclear positioning...
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Balance error generated by numerical diffusion in the solution of Muskingum equation
PublikacjaIn the paper the conservative properties of the lumped hydrological models with variable parameters are discussed. It is shown that in the case of the non-linear Muskingum equation the mass balance is not satisfied. The study indicates that the mass balance errors are caused by the improper form of equation and by the numerical diffusion which is generated in the solution. It has been shown that the classical way of derivation...
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A Measurement-Based Approach for Speed Control of Induction Machines
PublikacjaThis paper presents an approach to design a measurement-based controller for induction machines. The proposed control approach is motivated by the fact that developing an appropriate mechanical model of such induction machines is a challenging task. Since our proposed control methodology is only on the basis of measured data, the controller design does not require any information about the model of the mechanical part. The control...
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Global value chains, wages, employment and labour production in China: A regional approach
PublikacjaIn this study we analyse the relationship of trade and global value chains (GVCs) to the labour market in 31 Chinese provinces for 25 sectors, by means of a system of structural equations. We firstly distinguish between provincial value chains (PVCs) and interprovincial value chains (PRVCs) in order to outline their distribution and evolution over time. Then, we investigate to what extent participation in GVCs, PVCs and PRVCs –...
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Features of Nonlinear Sound Propagation in Vibrationally Excited Gases
PublikacjaWeakly nonlinear sound propagation in a gas where molecular vibrational relaxation takes place is studied. New equations which govern the sound in media where the irreversible relaxation may take place are derived and discussed. Their form depends on the regime of excitation of oscillatory degrees of freedom, equilibrium (reversible) or non-equilibrium (irreversible), and on the comparative frequency of the sound in relation to...
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AN OVERVIEW OF HEAT TRANSFER ENHANCEMENT BASED UPON NANOPARTICLES INFLUENCED BY INDUCED MAGNETIC FIELD WITH SLIP CONDITION VIA FINITE ELEMENT STRATEGY
PublikacjaThe mathematical model of heat generation and dissipation during thermal energy transmission employing nanoparticles in a Newtonian medium is investigated. Dimensionless boundary layer equations with correlations for titanium dioxide, copper oxide, and aluminium oxide are solved by the finite element method. Parameters are varied to analyze their impact on the flow fields. Various numerical experiments are performed consecutively...
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On Wrinkling in Sandwich Panels with an Orthotropic Core
PublikacjaThis paper deals with the local loss of stability (wrinkling) problem of a thin facing of a sandwich panel. Classical solutions to the problem of facing instability resting on a homogeneous and isotropic substructure (a core) are compared. The relations between strain energy components associated with different forms of core deformations are discussed. Next, a new solution for the orthotropic core is presented in detail, which...
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Buckling of thin-walled columns accounting for initial geometrical imperfections
PublikacjaThe paper is devoted to the effect of some geometrical imperfections on the critical buckling load of axially compressed thin-walled I-columns. The analytical formulas for the critical torsional and flexural buckling loads accounting for the initial curvature of the column axis or the twist angle respectively are derived. The classical assumptions of theory of thin-walled beams with non-deformable cross-sections are adopted. The...
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An interval estimator for chlorine monitoring in drinking water distribution systems under uncertain system dynamics, inputs and chlorine concentration measurement errors
PublikacjaThe design of an interval observer for estimation of unmeasured state variables with application to drinking water distribution systems is described. In particular, the design process of such an observer is considered for estimation of the water quality described by the concentration of free chlorine. The interval observer is derived to produce the robust interval bounds on the estimated water quality state variables. The stability...
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A Comparison of Simplified Two-dimensional Flow Models Exemplified by Water Flow in a Cavern
PublikacjaThe paper shows the results of a comparison of simplified models describing a two-dimensional water flow in the example of a water flow through a straight channel sector with a cavern. The following models were tested: the two-dimensional potential flow model, the Stokes model and the Navier-Stokes model. In order to solve the first two, the boundary element method was employed, whereas to solve the Navier-Stokes equations, the...
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Nonlinear phenomena of small-scale sound in a gas with exponential stratification
PublikacjaThe nonlinear dynamics of perturbations, quickly varying in space, with comparatively large characteristic wavenumbers k: k>1/H, is considered. H is the scale of density and pressure reduction in unperturbed gas, as the coordinate (H is the so-called height of the uniform equilibrium gas). Coupling nonlinear equations which govern the sound and the entropy mode in a weakly nonlinear flow are derived. They describe the dynamics...
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Analytical design method of reverse curves
PublikacjaThe paper deals with a new approach relating to the design of the region of railway track direction alteration adapted to Mobile Satellite Measurements technique. The method may be particularly useful in situations when both the straights of the route directions cannot be connected in an elementary way using a circular arc with transition curves; this also refers to the application of a compound curve. Thus the only solution becomes...
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Mathematical modeling and prediction of pit to crack transition under cyclic thermal load using artificial neural network
PublikacjaThe formation of pitting is a major problem in most metals, which is caused by extremely localized corrosion that creates small holes in metal and subsequently, it changes into cracks under mechanical load, thermo-mechanical stress, and corrosion process factors. This research aims to study pit to crack transition phenomenon of steel boiler heat tubes under cyclic thermal load, and mathematical modeling...
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Direct-contact condensation from vapour- gas mixture in a spray ejector condenser for negative CO2 power plant
PublikacjaDirect-contact condensation of vapour containing the inert gas on a spray of subcooled liquid exists in a number of technical applications. For example, it may be found in the nuclear industry (e.g. pressurized jet under normal operating conditions, in safety analyses) or in the chemical industry (e.g. mixing-type heat exchanger, degasser, sea water desalting). The problem is also essential to modelling and analysis of some...
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Analiza działania rozszerzonego obserwatora prędkości w szerokim zakresie zmian prędkości maszyny indukcyjnej
PublikacjaW artykule przedstawiono zagadnienia związane z odtwarzaniem zmiennych stanu maszyny indukcyjnej. Wykorzystano obserwator oparty na modelu matematycznym maszyny z dodatkowymi zmiennymi. Przedstawiono macierz stanu zlinearyzowanych równań błędu odtwarzania. Opisano sposób definiowania wyznacznika jakości na podstawie rozkładu biegunów obserwatora. Zaproponowano metodę korekcji wzmocnień wraz ze zmianą warunków pracy maszyny. Wykazano...
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Continuum orbitals in low energy scattering of electrons from Ar, Kr, Xe, Rn and Og atoms
Dane BadawczeThe dataset includes relativistic continuum electron wave functions (continuum orbitals, continuum spinors) for elastic scattering of electrons from Argon (Ar), Krypton (Kr), Xenon (Xe), Radon (Rn) and Oganesson (Og) atoms, calculated using the Multiconfiguration Dirac-Hartree-Fock method (MCDHF), at very low electron energies (0.0001 - 0.001 eV). Only...
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Tuning matrix-vector multiplication on GPU
PublikacjaA matrix times vector multiplication (matvec) is a cornerstone operation in iterative methods of solving large sparse systems of equations such as the conjugate gradients method (cg), the minimal residual method (minres), the generalized residual method (gmres) and exerts an influence on overall performance of those methods. An implementation of matvec is particularly demanding when one executes computations on a GPU (Graphics...
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Relativity of arithmetic as a fundamental symmetry of physics
PublikacjaArithmetic operations can be defined in various ways, even if one assumes commutativity and associativity of addition and multiplication, and distributivity of multiplication with respect to addition. In consequence, whenever one encounters ‘plus’ or ‘times’ one has certain freedom of interpreting this operation. This leads to some freedom in definitions of derivatives, integrals and, thus, practically all equations occurring in...
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Mathematical modelling of the overhead contact line for the purpose of diagnostics of pantographs
PublikacjaThe overhead contact line (OCL) is the most effective way for supplying railway electric vehicles. The increase of the speed of the vehicles increases power consumption and requires ensuring proper cooperation of pantographs with OCL. The paper describes the novel mathematical model of the OCL system and the simulation results. The primary objective is a more accurate analysis to increase the reliability of the evaluation of monitoring...
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Geometry Parametric Model Order Reduction with Randomly Generated Projection Bases
PublikacjaIn this work, a reduced-order model for geometry parameters and fast frequency sweep is proposed. The Finite Element Method is used to solve time-harmonic Maxwell’s equations. Taking into account the electromagnetic field does not arbitrarily vary as a function of frequency and geometry parameters, a low dimension system manifold is identified. Thus, the original Finite Element problem can be approximated by a model of reduced...
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Experimental and numerical studies on the mechanical response of a piezoelectric nanocomposite-based functionally graded materials
PublikacjaThis work presents an experimental study of piezoelectric structures reinforced by graphene platelets, based on the concept of the functionally graded materials (FGMs). The assumed model is a rectangular beam/plate and the composition is due to the Halpin-Tsai rule. The model is also simulated in the Abaqus software which is the first time that such a structure has been modelled in an FEM package. In addition, a mathematical model...
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Excitation of Non-Wave Modes by Sound of Arbitrary Frequency in a Chemically Reacting Gas
PublikacjaThe nonlinear phenomena in the field of high intensity sound propagating in a gas with a chemical reaction, are considered. A chemical reaction of A → B type is followed by dispersion and attenuation of sound which may be atypical during irreversible thermodynamic processes under some conditions. The first and second order derivatives of heat produced in the chemical reaction evaluated at the equilibrium temperature, density and...
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Buckling Analysis of a Micro Composite Plate with Nano Coating Based on the Modified Couple Stress Theory
PublikacjaThe present study investigates the buckling of a thick sandwich plate under the biaxial non-uniform compression using the modified couple stress theory with various boundary conditions. For this purpose, the top and bottom faces are orthotropic graphene sheets and for the central core the isotropic soft materials are investigated. The simplified first order shear deformation theory (S-FSDT) is employed and the governing differential...
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Differential Quadrature Method for Dynamic Buckling of Graphene Sheet Coupled by a Viscoelastic Medium Using Neperian Frequency Based on Nonlocal Elasticity Theory
PublikacjaIn the present study, the dynamic buckling of the graphene sheet coupled by a viscoelastic matrix was studied. In light of the simplicity of Eringen's non-local continuum theory to considering the nanoscale influences, this theory was employed. Equations of motion and boundary conditions were obtained using Mindlin plate theory by taking nonlinear strains of von Kármán and Hamilton's principle into account. On the other hand, a...
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A subdomain model for armature reaction field and open‐circuit field prediction in consequent pole permanent magnet machines
PublikacjaIn this paper, the machine quantity, such as electromagnetic torque, self and mutual inductances, and electromotive force, is analytically calculated for non-overlapping winding consequent pole slotted machine for open-circuit field and armature reaction. The sub-domain approach of (2-D) analytical model is developed using Maxwell's equations and divide the problem into slots, slot-openings, airgap and magnets region, the magnet...
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Resistant to correlated noise and outliers discrete identification of continuous non-linear non-stationary dynamic objects
PublikacjaIn this article, specific methods of parameter estimation were used to identify the coefficients of continuous models represented by linear and nonlinear differential equations. The necessary discrete-time approximation of the base model is achieved by appropriately tuned FIR linear integral filters. The resulting discrete descriptions, which retain the original continuous parameterization, can then be identified using the classical...
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Resistant to correlated noise and outliers discrete identification of continuous non-linear non-stationary dynamic objects
PublikacjaIn this study, dedicated methods of parameter estimation were used to identify the coefficients of continuous models represented by linear and nonlinear differential equations. The necessary discrete-time approximation of the base model is achieved by appropriately tuned FIR linear integral filters. The resulting discrete descriptions, which retain the original continuous parameterization, can then be identified using the classical...
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Local and global response of sandwich beams made of GFRP facings and PET foam core in three point bending test
PublikacjaIn the paper behaviour of laminated sandwich beams (FRP face sheet – PET foam core – FRP face sheet) subjected to three point bending is studied. The paper aim is to find practical descriptions enabling effective and accurate estimation of the elastic response, damage and failure of the beams, basing on experiments and static calculations. Therefore a number of tests are described, that were done on laminated coupons and foam specimens...
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Sensorless low speed PMSM motor control with cogging torque compensation
PublikacjaThe paper presents sensorless control of a low speed permanent magnet synchronous machine with use of modified state observer. An overview of the PMSM motor used in the research setup was presented. The problem of drive torque ripple, resulting mainly from the occurrence of a significant cogging torque, was discussed. A solution compensating the torque ripple of the PMSM motor was proposed. A start-up procedure of the speed control...
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A method to determine the tightening sequence for standing rigging of a mast
PublikacjaThe article proposes an alternative method to determine the sequence of generation of pre-tension forces in standing rigging of a mast. The proposed approach has been verified on both a virtual simulation experiment and laboratory tests. In this method, the desired tension values are obtained using the influence matrix which allows to calculate the effect of tension change in an individual rope on the tension distribution in the...
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Exact resultant equilibrium conditions in the non-linear theory of branching and self-intersecting shells
PublikacjaWe formulate the exact, resultant equilibrium conditions for the non-linear theory of branching and self-intersecting shells. The conditions are derived by performing direct through-the-thickness integration in the global equilibrium conditions of continuum mechanics. At each regular internal and boundary point of the base surface our exact, local equilibrium equations and dynamic boundary conditions are equivalent, as expected,...
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Propagation of acoustic pulses in some fluids with yield stress
PublikacjaThis study is devoted to the derivation of approximate equations governing acoustic pulses in flows with yieldstress, including some time-dependent flows with a slow dependence on time of yield stress and apparent viscosity. Themodeling of yield stress and apparent viscosity in the vicinity of a zero deformation rate allows us to consider a thixotropicfluid as a Bingham plastic with coefficients that are dependent on time. The...