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Search results for: dynamic-algebraic equations
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Model of pressure distribution in vortex flow controls
PublicationThe paper is devoted to the vortex valve. Existing devices are described by CFD-methods, or by means of simple empirical relations. A rational method of the considered object design is proposed, on the base of the input and dissipation energy balance., what gives a simple algebraic equation. Conformity between calcul;ated and measured parameters of the vortex valve allows for acceptation of the proposed concept.
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Smooth Particle Hydrodynamics (SPH) approach in simulating large penetration into soil
PublicationA study of Smooth Particle Hydrodynamics (SPH) approach for predicting large soil deformation is presented. Theoretical basics of SPH method, including the equations governing, discussion of the importance of smoothing function length, contact formulation, boundary treatment and finally utilization in hydrocodes simulations are presented. An application of SPH to a real case of large penetrations (crater creating) into soil caused...
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Karolina Lademann Mgr
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Symbolic multibody models for digital-twin applications
PublicationSymbolic generation of multibody systems equations of motion appeared in the 1980s. In addition to their computational advantage over their numerical counterparts, symbolic models can be very easily and straightforwardly interfaced with a wide range of software environments and hardware devices. These two features place this approach in a pole position to participate and intervene in the design of digital twins for systems such...
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A Novel Approach to Fully Nonlinear Mathematical Modeling of Tectonic Plates
PublicationThe motion of the Earth's layers due to internal pressures is simulated in this research with an efficient mathematical model. The Earth, which revolves around its axis of rotation and is under internal pressure, will change the shape and displacement of the internal layers and tectonic plates. Applied mathematical models are based on a new approach to shell theory involving both two and three-dimensional approaches. It is the...
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Free-surface elevation in open vortex flow controls
PublicationRotational form of fluid motion is complex, but very important in science and technology. The paper is devoted to the hydraulic mechanism of flow in open vortex flow controls, or regulators. The velocity field was described by the kinematic model, and intensity of rotation - by means of the energy balance between the input and dissipation. In consequence some algebraic expresions were obtained, which can be useful in approximated...
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Analiza przepływu oleju przez rowek smarowy wzdłużnego łożyska ślizgowego z wykorzystaniem komputerowej dynamiki płynów (CFD) = Analysis of the lubricant flow through the hydrodynamic thrust bearings groove with the use of computational fluid dynamic
PublicationSmarowanie zanurzeniowe jest tradycyjnym sposobem smarowania wzdłużnych łożysk ślizgowych. Jednak rozwiązanie to wykazuje umiarkowaną skuteczność w zapewnieniu optymalnie niskich temperatur w filmie smarowym a ponadto jest przyczyną strat mocy związanych z mieszaniem oleju w obudowie łożyska, co jest szczególnie widoczne w łożyskach szybkoobrotowych. Obecnie wymagania stawiane nowym konstrukcjom łożysk ślizgowych to zwiększanie...
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Structural Stability of Nonautonomous Systems
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Chaos in vibroimpact systems with one degree of freedom in a neighborhood of chatter generation: II
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A Criterion for Conditional Instability by the First Approximation for Solutions of Differential Systems
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Chaos in vibroimpact systems with one degree of freedom in a neighborhood of chatter generation: I
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Robust identification of quadrocopter model for control purposes
PublicationThe 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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On the Nonlinear Effects of Magnetoacoustic Perturbations in Optically Thin Quasi-Isentropic Plasmas
PublicationNonlinear 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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Maximum transportation growth in energy and solute particles in Prandtl martial across a vertical 3D-heated surface: Simulations achieved using by finite element approach
PublicationThe 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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Multiple solutions for a class of boundary-value problems with deviating arguments and integral boundary conditions
PublicationPraca dotyczy istnienia dodatnich rozwiązań dla równań różniczkowych rzędu drugiego z całkowymi warunkami brzegowymi i z odchylonymi argumentami typu wyprzedzonego. Korzystając z tw. Avery-Petersona dla stożków, podano warunki dostateczne na istnienie trzech dodatnich rozwiazań w/w problemów. Podano przykład pokazujący iż przyjęte załozenia są spełnione.
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Positive solutions to third-order impulsive Sturm-Liouville boundary value problems with deviated arguments and one-dimensional p-Laplacian
PublicationBadane są równania różniczkowe z impulsami trzeciego rzędu z odchylonymi argumentami przy zadanych warunkach brzegowych typu Sturma-Liouvilla. Podano warunki dostateczne na istnienie dodatnich rozwiązań takich problemów stosując twierdzienie o punkcie stałym dla stożków.
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Boundary value problems with advanced arguments involving upper and lower solutions in reverse order
PublicationPraca dotyczy problemów brzegowych dla równań różniczkowo-całkowych pierwszego rzędu z argumentami wyprzedzonymi. Podano wystarczające warunki, dla których problemy dotyczące takich równań mają rozwiązania minimalne i maksymalne w odpowiadającym obszarze ograniczonym przez rozwiązania górne i dolne. W celu uzyskania wyników zastosowano nową metodę opartą na twierdzeniu Heikkila-Lakshmikantham'a. Wyniki zilustrowano na przykładzie.
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Ahmed Manguri PhD Student
PeopleI am a 1st year PhD student at Gdansk University of Technology in the field of Dynamic Analysis of Structures under the supervision of Prof. Jankowski. I did my MSc in structural Engineering at Cardiff University in the UK and BSc in civil Engineering at Koya University in Kurdistan. I have been an academic staff at University of raparin in Kurditan since 2016.
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Mechanical simulation of artificial gravity in torus-shaped and cylindrical spacecraft
PublicationLarge deformations and stress analyses in two types of space structures that are intended for people to live in space have been studied in this research. The structure under analysis is assumed to rotate around the central axis to create artificial gravitational acceleration equal to the gravity on the Earth's surface. The analysis is fully dynamic, which is formulated based on the energy method by using the first-order shear deformation...
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The modelling method of discrete-continuous systems
PublicationThe paper introduces a method of discrete-continuous systems modelling. In the proposed method a three-dimensional system is divided into finite elements in only two directions, with the third direction remaining continuous. The thus obtained discrete-continuous model is described by a set of partial differential equations. General difference equations of discrete system are obtained using the rigid finite element method. The limit...
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Katarzyna Tessmer mgr inż.
PeopleEducation 2012: B.Sc. in Financial Mathematics from the Faculty of Applied Physics and Mathematics, Gdansk University of Technology (2008 – 2012: Bachelor of Science Engineering Studies. Field of study: Mathematics. Specialization: Financial Mathematics.) 2014: M.Sc. in Financial Mathematics from the Faculty of Applied Physics and Mathematics, Gdansk University of Technology (2012 – 2014: Master of Science Engineering Studies....
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Sliding friction of alumina (Al2O3) with friction induced vibrations
Open Research DataTest files containing data on experiments in self mated sliding contact of alumina Al2O3 lubricated with either water or paraffin oil. Tests run in variable load/velocity conditions and with different dynamic settings of the test rig (PT-3 tribometer). The aim of the research was to attempt in finding correlations between the dynamic characteristics...
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Share of people working in the enterprise sector by ownership sector at the end of 2016 (%).
Open Research DataThe dynamic development of small and medium-sized enterprises, which was observed in the past century - in particular in the past two decades - is the phenomenon of the development of the world economy intriguing many researchers and research centers. These figures present the share of workforce according to the ownership sector at the end of 2016.
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Parametric method applicable in calculating breakout force and time for lifting axisymmetric objects from seabed.
PublicationThe issue of calculating parameters for lifting objects of axisymmetric shapes from the seabed is studied. The article presents the results of numerical simulation examination of the equation formulated by Foda for the force needed to extricate the object from the seabed depending on soil and water parameters, extrication speed, and object diameter. The simulations were performed within the range of parameters characteristic for...
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Analysis of the process of water entry of an amphibious vehicle
PublicationThe paper presents a method of computational and experimental analysis of the process of water entry of an amphibious vehicle. The computational method is based on the Reynolds Averaged Navier-Stokes Equations (RANSE) solver and the xperiment was carried out in the towing tank at Ship Design and Research Centre S.A. with the use of a scale model. The analysis was focused on the safety of water entry, i.e. the maximum pitch and...
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Nonlinear free and forced vibrations of a dielectric elastomer-based microcantilever for atomic force microscopy
PublicationThe majority of atomic force microcode (AFM) probes work based on piezoelectric actuation. However, some undesirable phenomena such as creep and hysteresis may appear in the piezoelectric actuators that limit their applications. This paper proposes a novel AFM probe based on dielectric elastomer actuators (DEAs). The DE is modeled via the use of a hyperelastic Cosserat model. Size effects and geometric nonlinearity are included...
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A Comparison of Empirical Correlations of Viscosity and Thermal Conductivity of Water-Ethylene Glycol-Al2O3 Nanofluids
PublicationBecause of their superb thermal conductivity, nanofluids are seen as new generation of cooling mediums in many engineering applications. It is well established that even a small amount of nanoparticles mixed with a base fluid may result in distinct thermal conductivity enhancement. On the other hand, addition of nanoparticles to the base fluid results in its substantial viscosity increase. Therefore, it is very dicult to evaluate...
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Dataset of phase portraits of the fractional prey-predator model with Holling type-II interaction (without predator harvesting)
Open Research DataThe need for a fractional generalization of a given classical model is often due to new behaviors which cannot be taken into account by the model. In this situation, it can be useful to look for a fractional deformation of the initial system, trying to fit the fractional exponent of differentiation in order to catch properly the data.
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Redundantly Actuated 3RRR Parallel Planar Manipulator - Numerical Analyses of its Dynamics Sensitivity on Modifications of its Platform’s Inertia Parameters
PublicationIn the paper, numerical analyses, as well as dynamics of a complex mechanism, are presented. Two objectives are crucial for the paper: inverse dynamic model is needed (dedicated to be use in the model predictive controller); an identification method is searched (some trajectory parameters are controlled, when specific trajectory is tracked under an open-loop model-based control), as selected parameters must be identified for the...
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Genetic Algorithm Approach for Gains Selection of Induction Machine Extended Speed Observer
PublicationThe subject of this paper is gains selection of an extended induction machine speed observer. A high number of gains makes manual gains selection difficult and due to nonlinear equations of the observer, well-known methods of gains selection for linear systems cannot be applied. A method based on genetic algorithms has been proposed instead. Such an approach requires multiple fitness function calls; therefore, using a quality index...
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Vibration signals collected for concrete beams with GFRP reinforcement subjected to elevated temperatures (120C-240C)
Open Research DataThe dataset contains the time domain signals obtained during dynamic tests of concrete beams reinforced with GFRP bars. The vibration were induced with the use of modal hammer, while the signals were collected by the accelerometers attached at the beam surface. The signals were captured before and after subjecting the concrete beams to elevated temperatures.
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Recycled Polyurethane as a Second Phase in Thermoset Blends and Its Effect on Thermal Degradation Kinetics Studies
PublicationA new approach is introduced in the modification of thermosetting polymer by using different amount of polyurethane of waste origin. The post consumer polyurethane foam coatings are degraded using glycolysis process and the recycled product is further converted into new polyurethane. The blending of recycled polyurethane with epoxy exhibits transparency and produces nanostructures. The effective interaction between two polymers...
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Nonlinear Interaction of Modes in a Planar Flow of a Gas with Viscous and Thermal Attenuation
PublicationThe nonlinear interaction of wave and non-wave modes in a gas planar flow are considered. Attention is mainly paid to the case when one sound mode is dominant and excites the counter-propagating sound mode and the entropy mode. The modes are determined by links between perturbations of pressure, density, and fluid velocity. This definition follows from the linear conservation equations in the differential form and thermodynamic...
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Fractional-order Systems and Synchronous Generator Voltage Regulator
PublicationModern regulators of synchronous generators, including voltage regulators, are digital systems, in their vast majority with standard structures contained in the IEEE standard. These are systems described with stationary differential equations of integral order. Differential equations of fractional order are not employed in regulators for synchronous generator control. This paper presents an analysis of the possibilities of using...
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Zdzisław Kowalczuk prof. dr hab. inż.
PeopleZdzislaw Kowalczuk received his M.Sc. degree in 1978 and Ph.D. degree in 1986, both in Automatic Control from Technical University of Gdańsk (TUG), Gdańsk, Poland. In 1993 he received his D.Sc. degree (Dr Habilitus) in Automatic Control from Silesian Technical University, Gliwice, Poland, and the title of Professor from the President of Poland in 2003. Since 1978 he has been with Faculty of Electronics, Telecommunications and Informatics...
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On solvability of initial boundary-value problems of micropolar elastic shells with rigid inclusions
PublicationThe problem of dynamics of a linear micropolar shell with a finite set of rigid inclusions is considered. The equations of motion consist of the system of partial differential equations (PDEs) describing small deformations of an elastic shell and ordinary differential equations (ODEs) describing the motions of inclusions. Few types of the contact of the shell with inclusions are considered. The weak setup of the problem is formulated...
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Periodic expansion in determining minimal sets of Lefschetz periods for Morse–Smale diffeomorphisms
PublicationWe apply the representation of Lefschetz numbers of iterates in the form of periodic expansion to determine the minimal sets of Lefschetz periods of Morse–Smale diffeomorphisms. Applying this approach we present an algorithmic method of finding the family of minimal sets of Lefschetz periods for Ng, a non-orientable compact surfaces without boundary of genus g. We also partially confirm the conjecture of Llibre and Sirvent (J Diff...
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Nilpotent singularities and chaos: Tritrophic food chains
PublicationLocal bifurcation theory is used to prove the existence of chaotic dynamics in two well-known models of tritrophic food chains. To the best of our knowledge, the simplest technique to guarantee the emergence of strange attractors in a given family of vector fields consists of finding a 3-dimensional nilpotent singularity of codimension 3 and verifying some generic algebraic conditions. We provide the essential background regarding...
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Analytical predictions for the buckling of a nanoplate subjected to non-uniform compression based on the four-variable plate theory
PublicationIn 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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Balancing energy processes in turbine engines
PublicationThe article discusses the issue of balancing energy processes in turbine engines in operation in aeronautic and PDULQHSURSXOVLRQV\VWHPVZLWKWKHDLPWRDQDO\VHDQGHYDOXDWH EDVLFRSHUDWLQJSDUDPHWHUV7KH¿UVWSDUWSUHVHQWV the problem of enormous amounts of energy needed for driving fans and compressors of the largest contemporary turbofan engines commonly used in long-distance aviation. The amounts of the transmitted power and the effect RIÀRZSDUDPHWHUVDQGFRQVWUXFWLRQDOSURSHUWLHVRIWKHHQJLQHV RQWKHLUSHUIRUPDQFHDQGUHDOHI¿FLHQF\DUH evaluated....
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A model development and experimental verification for a vapour microturbine with a permanent magnet synchronous generator
PublicationVapour microturbines with permanent magnet synchronous generators are implemented in micropower plants for dispersed power generation systems. The dynamic model of such a microturbine set was developed and presented. The developed relations result from the generic equations. Experimental data for two different working medium were used for model verification. A microturbine set model was tested during the changes in the parameters...
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A Universal Gains Selection Method for Speed Observers of Induction Machine
PublicationProperties of state observers depend on proper gains selection. Each method of state estimation may require the implementation of specific techniques of finding those gains. The aim of this study is to propose a universal method of automatic gains selection and perform its verification on an induction machine speed observer. The method utilizes a genetic algorithm with fitness function which is directly based on the impulse response...
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Numerical Methods
e-Learning CoursesNumerical Methods: for Electronics and Telecommunications students, Master's level, semester 1 Instructor: Michał Rewieński, Piotr Sypek Course description: This course provides an introduction to computational techniques for the simulation and modeling of a broad range of engineering and physical systems. Concepts and methods discussed are widely illustrated by various applications including modeling of integrated circuits,...
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Dyskretno-ciągła metoda modelowania układów dynamicznych
PublicationW artykule przedstawiono oryginalną metodę modelowania układów dyskretno-ciągłych. Metoda polega na dyskretyzowaniu układu trójwymiarowego jedynie w dwóch wybranych kierunkach. W trzecim z kierunków układ pozostaje ciągły. Otrzymany w ten sposób model jest modelem dyskretno-ciągłym. Opisany jest za pomocą równań różniczkowych cząstkowych. Ogólne równania różnicowe układu dyskretnego otrzymano, wykorzystując metodę sztywnych elementów...
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Validation of polyurethane-wood composites properties
Open Research DataThis study focuses on the development of the PU-WC manufacturing method, the determination of properties of this type of composite, and the indication of its potential application. The mechanical properties of PU-WC were characterized by flexural tests. To determine the thermal properties, dynamic mechanical analysis (DMA) and thermogravimetric analysis...
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Comparison and validation of integer and fractional order ultracapacitor models
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Point to point control of fractional differential linear control systems
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Heteroclinic solutions for a class of the second order Hamiltonian systems
PublicationW pracy dowodzi się istnienia rozwiązań heteroklicznicznych dla pewnej klasy równań różniczkowych zwyczajnych drugiego rzędu typu hamiltonowskiego.
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Homoclinic solutions for a class of the second order Hamiltonian systems
PublicationW niniejszej pracy badamy istnienie orbit homoklinicznych dlaukładu Hamiltonowskiego drugiego rzędu: q^{..} + V_{q}(t,q) = f(t), gdzie V z iloczynu kartezjańskiego R x R^{n} do R jest postaciV(t,q) = -K(t,q) + W(t,q). Zakładamy, ze V jest T-okresowe ze względuna zmienną t, K spełnia tzw. ''pinching'' warunek, W jest superliniowew nieskończoności, a norma f w L^{2} jest wystarczająco mała.Orbitę homokliniczną takiego układu znajdujemy...
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The cohomological span of LS-Conley index
PublicationIn this paper we introduce a new homotopy invariant – the cohomological span of LS-Conley index. We prove the theorems on the existence of critical points for a class of strongly indefinite functionals with the gradient of the form Lx+K(x), where L is bounded linear and K is completely continuous. We give examples of Hamiltonian systems for which our methods give better results than the Morse inequalities. We also give a formula...