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Search results for: COUPLING DYNAMIC EQUATIONS
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The Experimental Determination of Bearings Dynamic Coefficients in a Wide Range of Rotational Speeds, Taking into Account the Resonance and Hydrodynamic Instability
PublicationMethods for the experimental determination of dynamic coefficients are commonly used for the analysis of various types of bearings, including hydrodynamic, aerodynamic and foil bearings. There are currently several algorithms that allow estimating bearing dynamic coefficients. Such algorithms usually use various excitation techniques applied to rotor–bearings systems. So far only a small number of scientific publications show how...
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Modal properties identification of a novel sandwich footbridge – Comparison of measured dynamic response and FEA
PublicationA modern sandwich composite footbridge made of high-tech materials, being an example of practical application of laminated composites in civil engineering, is presented. The in situ non-destructive testing of the footbridge, aiming to identify modal properties and pedestrian comfort, is described. The measured eigenmodes and eigenfrequencies are compared with numerically estimated values. Finite element analyses of the footbridge...
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Determination of the dynamic critical maneuvering area in an encounter between two vessels: Operation with negligible environmental disruption
PublicationThis paper introduces the concept of Collision Avoidance Dynamic Critical Area (CADCA) for onboard Decision Support Systems (DSS). The indicator proposed is derived via identification of a minimum required maneuvering zone in an encounter between two vessels. The CADCA model accounts for ship maneuvering dynamics and associated hydrodynamic actions emerging from different rudder angles and forward speed effects. The method presented...
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Incremental Dynamic Analysis and Fragility Assessment of Buildings with Different Structural Arrangements Experiencing Earthquake-Induced Structural Pounding
PublicationStructural pounding is considered as one of the most critical phenomena occurring during earthquakes. This paper presents the incremental dynamic analysis and fragility assessment of buildings experiencing earthquake-induced pounding. Three 3-D buildings with different number of storeys and under different structural arrangements have been considered. Three pounding scenarios have been taken into account, i.e. pounding between...
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Determination of the optimal curvature of the turnout diverging track for HSR using dynamic analysis
PublicationThe paper presents an analytical method of identifying the curvature of the turnout diverging track consisting of sections of varying curvature. Such turnout is mainly applied on High Speed Railway. Both linear and nonlinear (polynomial) curvatures of the turnout diverging track are considered in the paper. Obtained solutions enable to assume curvature values at the beginning and end point of the geometrical layout of the turnout.The...
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Creating Dynamic Maps of Noise Threat Using PL-Grid Infrastructure
PublicationThe paper presents functionality and operation results of a system for creating dynamic maps of acoustic noise employing the PL-Grid infrastructure extended with a distributed sensor network. The work presented provides a demonstration of the services being prepared within the PLGrid Plus project for measuring, modeling and rendering data related to noise level distribution in city agglomerations. Specific computational environments,...
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Merton-type default risk and financial performance: the dynamic panel moderation of firm size
PublicationPurpose – The main purpose of this study is to evaluate the probability of default and examine the relationship between default risk and financial performance, with dynamic panel moderation of firm size. Design/methodology/approach – This study utilizes a total of 1,500 firm-year observations from 2013 to 2018 using dynamic panel data approach of generalized method of moments to test the relationship between default risk and financial...
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The influence of dynamic load changes on temporary impedance in hydrogen fuel cells, selection and validation of the electrical equivalent circuit
PublicationTo achieve optimal performance of a fuel cell, a reliable monitoring and diagnostic method is required. The currently utilized methods give limited information or they are impossible to use under dynamic working conditions. To obtain comprehensive information about the fuel cell operation we utilized novel dynamic electrochemical impedance spectroscopy. Impedance measurements in dynamic mode were performed on a hydrogen fuel cell,...
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Modified nanodiamond particle size studies by means of dynamic light scattering technique
PublicationThe Methods Utilizing the Phenomena of Light Scattering to Measure Particle Size distribution in different solvent, such as deionise water and alcohol and also to study the various structural formation when nanodiamond solution is placed on silicon surface. The purpose of this research project is divided into two parts to configure the measurement units for examining modified nanodiamond particles, examination...
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Modified nanodiamond particle size studies by means of dynamic light scattering technique
PublicationThe Methods Utilizing the Phenomena of Light Scattering to Measure Particle Size distribution in different solvent, such as deionise water and alcohol and also to study the various structural formation when nanodiamond solution is placed on silicon surface. The purpose of this research project is divided into two parts to configure the measurement units for examining modified nanodiamond particles, examination...
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Research on the effect of low-sulphur marine fuels on the dynamic characteristics of a CI engine
PublicationThe implementation of low-sulphur, so-called modified marine fuels into operation requires prior labora- tory engine tests to assess the energy, emission and structural effects of their usage. This type of research are carried out on the test bed of a diesel engine as a small-scale physical model that reproduces the adequate design and process (parametric) features of a full-size marine engine. Their key stage is to determine the energy...
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Extraction and evaluation of gas-flow-dependent features from dynamic measurements of gas sensors array
PublicationGas analyzers based on gas sensors are the devices which enable recognition of various kinds of volatile compounds. They have continuously been developed and investigated for over three decades, however there are still limitations which slow down the implementation of those devices in many applications. For example, the main drawbacks are the lack of selectivity, sensitivity...
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Evaluation of Temperature Influence on Electrochemical Processes Occurring in a Lithium-Ion Supercapacitor with the Use of Dynamic Electrochemical Impedance Spectroscopy
PublicationIn order to obtain the full impedance characteristics of a lithium-ion capacitor as a function of temperature, the authors proposed the use of dynamic electrochemical impedance spectroscopy. Impedance tests were carried out under wide range of dynamic temperature changes for lithium-ion supercapacitors. Significant differences in electrochemical processes were observed as a result of working temperature. Moreover, the quality of...
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Dynamic polarizability of the relativistic hydrogenlike atom: Application of the Sturmian expansion of the Dirac-Coulomb Green function
PublicationWe utilize the Sturmian expansion of the Dirac-Coulomb Green function [R. Szmytkowski, J. Phys. B 30, 825 (1997)] to obtain components of the dynamic dipole polarizability tensor of the relativistic hydrogenlike atom in the ground state. It is found that the tensor may be expressed in terms of two independent quantities: a scalar polarizability and a vector polarizability, the latter being of the relativistic origin. In the static...
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The dynamic performance analysis of the Micro-turbine's rotor supparted on slide and roling element bearings
PublicationThis article presents the results of investigations of dynamic characteristics of a small-dimension rotor with slide and rolling element bearings. The object of investigations was the rotor-bearing system designed for the ORC based low-power steam micro-turbine. The investigations were performed using MESWIR series programs, as well as commercial FEA software ABAQUS and MADYN 2000. The results of modal analysis of the micro-rotor...
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Numerical investigation on dynamic performance of a multi-storey steel structure model and comparison with experimental results
PublicationShaking table testing is the most commonly adopted method to simulate earthquake forces. This approach allows us to analyze the dynamic performance and provides a valuable insight into the dynamics of building structures, which helps to improve their future safety and reliability. The present study aims to conduct a numerical evaluation of dynamic response of a multi-storey steel structure model, which was previously examined during...
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Numerical Investigation on Dynamic Performance of a Multi-storey Steel Structure Model and Comparison with Experimental Results
PublicationShaking table testing is the most commonly adopted method to simulate earthquake forces. This approach allows us to analyze the dynamic performance and provides a valuable insight into the dynamics of building structures, which helps to improve their future safety and reliability. The present study aims to conduct a numerical evaluation of dynamic response of a multi-storey steel structure model, which was previously examined during...
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STUDY OF ARRAY OF MEMS INERTIAL MEASUREMENT UNITS UNDER QUASI-STATIONARY AND DYNAMIC CONDITIONS
PublicationA measurement system includes all components in a chain of hardware and software that leads from a measured variable to processed data. In that context, the type and quality of the sensors or measuring devices are critical to any measurement system. MEMS/IMU sensors lag behind leading technologies in this respect, but the MEMS/IMU performance rapidly changes while is relatively inexpensive. For this reason, the paper proposes...
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Tuning a Hybrid GPU-CPU V-Cycle Multilevel Preconditioner for Solving Large Real and Complex Systems of FEM Equations
PublicationThis letter presents techniques for tuning an accelerated preconditioned conjugate gradient solver with a multilevel preconditioner. The solver is optimized for a fast solution of sparse systems of equations arising in computational electromagnetics in a finite element method using higher-order elements. The goal of the tuning is to increase the throughput while at the same time reducing the memory requirements in order to allow...
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Adaptive Optimal Discrete-Time Output-Feedback Using an Internal Model Principle and Adaptive Dynamic Programming
PublicationIn order to address the output feedback issue for linear discrete-time systems, this work suggests a brand-new adaptive dynamic programming (ADP) technique based on the internal model principle (IMP). The proposed method, termed as IMP-ADP, does not require complete state feedback, merely the measurement of input and output data. More specifically, based on the IMP, the output control problem can first be converted into a stabilization...
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A higher order transversely deformable shell-type spectral finite element for dynamic analysis of isotropic structures
PublicationThis paper deals with certain aspects related to the dynamic behaviour of isotropic shell-like structures analysed by the use of a higher order transversely deformable shell-type spectral finite element newly formulated and the approach known as the Time-domain Spectral Finite Element Method (TD-SFEM). Although recently this spectral approach is reported in the literature as a very powerful numerical tool used to solve various...
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Solving Boundary Value Problems for Second Order Singularly Perturbed Delay Differential Equations by ε-Approximate Fixed-Point Method
PublicationIn this paper, the boundary value problem for second order singularly perturbed delay differential equation is reduced to a fixed-point problem v = Av with a properly chosen (generally nonlinear) operator A. The unknown fixed-point v is approximated by cubic spline vh defined by its values vi = vh(ti) at grid points ti, i = 0, 1, ... ,N. The necessary for construction the cubic spline and missing the first derivatives at the boundary...
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Robust Parameter Estimation and Output Prediction for Reactive Carrier-Load Nonlinear Dynamic Networks
PublicationIn this paper an extension of on-line model simplification technique for a class of networked systems, namely reactive carrier-load nonlinear dynamic networked system (RCLNDNS), kept within point-parametric model (PPM) framework is addressed. The PPM is utilised to acquire a piece wise constant time-varying parameter linear structure for the RCLNDNS suitable for the on-line one step ahead prediction that may be applied to monitoring...
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The experimental identification of the dynamic coefficients of two hydrodynamic journal bearings operating at constant rotational speed and under nonlinear conditions.
PublicationHydrodynamic bearings are commonly used in ship propulsion systems. Typically, they are calculated using numerical or experimental methods. This paper presents an experimental study through which it has been possible to estimate 24 dynamic coefficients of two hydrodynamic slide bearings operating under nonlinear conditions. During the investigation, bearing mass coefficients are identified by means of a newly developed algorithm....
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Multistage Coupling of Eight Mistuned Bladed Disk on a Solid Shaft, Part 1 Free Vibration Analysis
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Study of Direct Methanol Fuel Cell Process Dynamics Using Dynamic Electrochemical Impedance Spectroscopy
PublicationA new technique, which was developed to characterize the direct methanol fuel cell under work conditions, has been presented in this paper. The impedance measurements were made using dynamic electrochemical impedance spectroscopy research technique in the galvanostatic mode, using multiple sinusoidal excitation. Obtained results show, that together with an increase of the temperature and working load, the global impedance...
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Dynamic impedance measurements of the Direct Methanol Fuel Cell cathode at various operating temperatures
PublicationThis article discusses the application of impedance analysis for diagnosing the cathode of a direct methanol fuel cell at various operating temperatures. The Dynamic Electrochemical Impedance Spectroscopy technique coupled with a linear current scan was applied for this purpose. This technique allowed the observation of changes in the cathode's properties in the fuel cell operating under real working conditions. An equivalent model...
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DYNAMIC MECHANICAL BEHAVIOUR OF GFRP COMPOSITES WITH SiO2 NANO PARTICLES REINFORCED EPOXY MATRIX
PublicationDynamic mechanic (DMA) tests were performed to compare the mechanical behaviour of glass fibre reinforced epoxy laminate composites with SiO2 nanoparticle reinforced matrix. The selection of the most promising nanoparticle concentrations was considered in terms of elastic modulus and glass transition temperature. The reference specimens (0% nanoparticles) did not contain diluent accordingly the results do not allow the exact comparison...
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The early failure of the gamma nail and the dynamic hip screw in femurs with a wide medullary canal. A biomechanical study of intertrochanteric fractures
PublicationBackground: Intertrochanteric fractures may occur in a bone with a wide medullary canal that may lead to significant mobility of a intramedullary nail, contrary to an extramedullary device. This study evaluates the Dynamic Hip Screw and the gamma nail in AO 31.A2.1 fractures in these circumstances. Methods: Synthetic femora with canals drilled to 18 mm were used. Five fixation types were examined: a 2 - hole and a 4 – hole Dynamic...
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Alternative Approach to Convolution Term of Viscoelasticity in Equations of Unsteady Pipe Flow
PublicationIn the paper the selected aspects concerning description of viscoelastic behavior of pipe walls during unsteady flow are analyzed. The alternative convolution expression of the viscoelastic term is presented and compared with the corresponding term referring to unsteady friction. Both approaches indicate similarities in the forms of impulse response functions and the parameter properties. The flow memory was introduced into convolution...
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Existence results to delay fractional differential equations with nonlinear boundary conditions
PublicationPraca dotyczy problemów brzegowych dla ułamkowych równań różniczkowych z opóźnionym argumentem. Podano warunki dostateczne na istnienie rozwiązań ekstremalnych takich zagadnień.
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Generalized Euler method for nonlinear first order partial differential equations.
PublicationKlasyczne rozwiązania nieliniowych równań różniczkowych cząstkowych pierwszego rzędu są aproksymowane w tej pracy za pomocą rozwiązań quasiliniowych układów równań różnicowych. Podstawowa idea pracy jest oparta na teorii charakterystyk. Podane są warunki wystarczające dla zbieżności metody. Dowód stabilności schematu różnicowego wykorzystuje metodę porównawczą z nieliniowymi oszacowaniami typu Perrona dla danych funkcji.Podane...
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Numerical modelling of elasto-viscoplastic Chaboche constitutive equations using MSC.Marc.
PublicationArtykuł omawia wykorzystanie specjalnej procedury UVSCPL umożliwiającej wprowadzenie do komercyjnego programu MSC.Marc sprężysto-lepkoplastycznych równań modelu Chaboche'a. Prezentuje szereg przykładów numerycznych, które potwierdzają poprawność zaproponowanej koncepcji analizy konstrukcji z wykorzystaniem rozpatrywanego prawa Chaboche'a ze zniszczeniem.
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Quadratic convergence of monotone iterations for differential equations with initial time difference
PublicationPodano warunki dostateczne na to, aby iteracje monotoniczne były zbieżne do jedynego rozwiązania równania różniczkowego przy różnych warunkach początkowych. Pokazano, że jest to zbieżność kwadratowa.
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Interaction of vortical and acoustic waves: from general equations to integrable cases
PublicationWyprowadzono operatory rzutu przepływu w warstwie lepkiej przyściennej na podstawowe typy ruchów. Wyprowadzono również układy równań dynamicznych sterujących przepływem. Zaproponowano metody analityczne dalszego rozwiązywania tych równań.
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Implicit difference methods for first order partial differential functional equations
PublicationW pracy prezentowana jest nowa klasa metod numerycznych dla quasiliniowych równań różniczkowo funkcyjnych pierwszego rzędu. Są to schematy różnicowe uwikłane względem zmiennej czasowej. Podana jest pełna analiza zbieżności rozważanych metod uwikłanych oraz przykład numeryczny pokazujący, że klasa tych metod jest szersza niż klasa schematów jawnych. Dowód stabilności opiera się na technice porównawczej z nieliniowym oszacowaniem...
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Implicit difference methods for nonlinear first order partial differential equations
PublicationW pracy klasyczne rozwiązania początkowo brzegowych problemów dla nieliniowych równań różniczkowych, szacowane są przez rozwiązania quasiliniowych układów uwikłanych równań różnicowych. Dowód zbieżności rozważanych metod opiera się na technice porównawczej z nieliniowym oszacowaniem typu Perrona dla funkcji danych. To nowe podejście do uwikłanych metod różnicowych dla równań nieliniowych opiera się na quasilinearyzacji tych metod...
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Boundary value problems for first order differential equations of mixed type
PublicationPraca dotyczy równań różniczkowo-całkowych z nieliniowymi warunkami brzegowymi. Podano warunki dostateczne na istnienie jedynego rozwiązania oraz rozwiązań ekstremalnych takich problemów. Dyskutowane są nierówności różniczkowo-całkowe. Podano przykłady ilustrujące otrzymane wyniki teoretyczne.
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Implicit difference methods for infinite systems of hyperbolic functional differential equations
PublicationPraca dotyczy klasycznych rozwiązań problemów początkowo brzegowych dla nieskończonych układów nieliniowych równań rózniczkowo funkcyjnych. Skonstruowane są dwa typy schematów różnicowych. Pokazujemy, ze rozwiązania rozważanego zagadnienia różniczkowego można przybliżyć przy pomocy rozwiązań nieskończonych układów równań różnicowych. W drugiej części pracy udowadniamy, że również rozwiązania skończonych układów równań różnicowych...
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Characteristic equations for the lasing modes of infinite periodic chain of quantum wires
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First-order functional difference equations with nonlinear boundary value problems
PublicationDyskutowano problem brzegowy dla równań różnicowych z opóźnionym argumentem. Nierówności różnicowe związane z w/w problem też były przedmiotem badań. Stosując metodę iteracji monotonicznych, sformułowano warunki dostateczne na istnienie ekstremalnych rozwiązań problemów brzegowych z opóźnionymi argumentami. Podano dwa przykłady ilustrujące otrzymane wyniki.
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Quasilinearization methods for nonlinear differential-functional parabolic equations: unbounded case
PublicationRozważamy zagadnienie Cauchy'ego dla nieliniowych równań parabolicznych z zależnością funkcyjną. Przedstawiamy rezultaty dotyczące zbieżności metody quasilinearyzacji dla rozwiązań nieograniczonych.
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Existence and uniqueness for neutral equations with delay dependant on a solution and its derivative
PublicationDla wykazania istnienia i jednoznaczności w pracy została zaprezentowana metoda porównawcza.
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Generalized method of lines for nonlinear first order partial differential equations
PublicationKlasyczne rozwiązania zagadnień początkowych oraz początkowo brzegowych są przybliżane za pomocą rozwiązań równań różniczkowo różnicowych. Skonstruowana jest metoda prostych polegająca na dyskretyzacji wyjściowego równania względem zmiennych przestrzennych. Przedstawiony w pracy schemat bazuje na metodzie linearyzacji dla zagadnień nieliniowych. W pracy zastosowano metodę quasilinearyzacji polegającą na zamianie nieliniowego równania...
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Generalized Euler method for first order partial differential functional equations
PublicationW pracy prezentowana jest nowa klasa metod numerycznych dla nieliniowych równań różniczkowo funkcyjnych pierwszego rzędu.Rozwiązania klasyczne zagadnień początkowo brzegowych przybliżane są w tej pracy przez rozwiązania odpowiedniego układu quasilininowego równań różnicowych. Podajemy kompletną analizę zbieżności metod i pokazujemy na przykładach, iż nowa metoda jest zauważalnie lepsza niż klasyczne schematy różnicowe. Dowód stabilności...
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Existence of solutions for second order impulsive differential equations with deviating arguments
PublicationPraca dotyczy równań różniczkowych z impulsami i odchylonymi argumentami. Badano problem istnienia rozwiązań stosując metodę iteracji monotonicznych opartą na dolnych i górnych rozwiązaniach. Praca uogólnia szereg znanych wyników.
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The generalized quasilinearization for integro-differential equations of Volterra type on time scales
PublicationBadano równania całkowo-różniczkowe on ''time scales'' i podano warunkidostateczne na zbieżność metody kwazilinearyzacji do jego rozwiązania. Podano warunki na to, aby zbieżność ta była kwadratową.
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Characteristics of Superconducting State in Vanadium: the Eliashberg Equations and Semi-analytical Formulas
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Implicit difference methods for quasilinear differential functional equations on the Haar pyramid
PublicationW pracy prezentowana jest klasa metod numerycznych dla quasiliniowych równań różniczkowo funkcyjnych pierwszego rzędu. Metody numeryczne są uwikłane względem zmiennej czasowej. Istnienie rozwiązania przybliżonego wykazane zostało przy użyciu nierówności różnicowych. Dowód stabilności bazuje na technice porównawczej z nieliniowym oszacowaniem typu Perona dla funkcji danych. Przedstawione zostały również przykłady numeryczne.
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Heteroclinic solutions of Allen-Cahn type equations with a general elliptic operator
PublicationWe consider a generalization of the Allen-Cahn type equation in divergence form $-\rm{div}(\nabla G(\nabla u(x,y)))+F_u(x,y,u(x,y))=0$. This is more general than the usual Laplace operator. We prove the existence and regularity of heteroclinic solutions under standard ellipticity and $m$-growth conditions.