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Wyniki wyszukiwania dla: NONLINEAR METHOD
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Introducing a Computational Method to Retrofit Damaged Buildings under Seismic Mainshock-Aftershock Sequence
PublikacjaRetrofitting damaged buildings is a challenge for engineers, since commercial software does not have the ability to consider the local damages and deformed shape of a building resulting from the mainshock record of an earthquake before applying the aftershock record. In this research, a computational method for retrofitting of damaged buildings under seismic mainshock-aftershock sequences is proposed, and proposed computational...
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The equations for interactions of polarization modes in optical fibres including the kerr effect
PublikacjaWe have derived coupled nonlinear Schro¨ dinger equations (CNLSE) for arbitrary polarized light propagation in a single-mode fibre employing electromagnetic field complete description. We used a basis of transverse eigenmodes with appropriate projecting; hence, the nonlinear constants depend on the waveguide geometry. Accounting for a weak nonlinearity, which is connected to the Kerr effect, we have given explicit expressions for...
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An Instantaneous Engine Speed Estimation Method Using Multiple Matching Synchrosqueezing Transform
PublikacjaInstantaneous rotational speed measurement of the engine is crucial in routine inspection and maintenance of an automobile engine. Since the contact measurement of rotational speed is not always available, the vibration measurement has been used for noncontact rotational speed estimation methods. Unfortunately, the accuracy of the noncontact estimation methods by analyzing engine vibration frequency is not satisfactory due to the...
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Modeling of Composite Shells in 6-Parameter Nonlinear Theory with Drilling Degree of Freedom
PublikacjaWithin the framework of a 6-parameter nonlinear shell theory, with strain measures of Cosserat type, constitutive relations are proposed for thin elastic composite shells. The material law is expressed in terms of five engineering constants of classical anisotropic continuum plus an additional parameter accounting for drilling stiffness. The theory allows for unlimited displacements and rotations. A number of examples are presented...
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Systems of boundary value problems of advanced differential equations
PublikacjaThis paper considers the existence of extremal solutions to systems of advanced differential equations with corresponding nonlinear boundary conditions. The monotone iterative method is applied to obtain the existence results. An example is provided for illustration.
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Strong ellipticity conditions and infinitesimal stability within nonlinear strain gradient elasticity
PublikacjaWe discuss connections between the strong ellipticity condition and the infinitesimal instability within the nonlinear strain gradient elasticity. The strong ellipticity (SE) condition describes the property of equations of statics whereas the infinitesimal stability is introduced as the positive definiteness of the second variation of an energy functional. Here we establish few implications which simplify the further analysis...
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Linear and Nonlinear Optical Properties of Azobenzene Derivatives Modified with an (Amino)naphthalene Moiety
PublikacjaThe design of two-photon absorbing azobenzene (AB) derivatives has received much attention; however, the two-photon absorption (2PA) properties of bis-conjugated azobenzene systems are relatively less explored. Here, we present the synthesis of six azobenzene derivatives and three bisazobenzenes substituted (or not) at para position(s) with one or two amino group(s). Their linear and nonlinear absorption properties are studied...
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ON DYNAMICS OF ELASTIC NETWORKS WITH RIGID JUNCTIONS WITHIN NONLINEAR MICRO-POLAR ELASTICITY
PublikacjaWithin the nonlinear micropolar elasticity we discuss effective dynamic (kinetic) properties of elastic networks with rigid joints. The model of a hyperelastic micropolar continuum is based on two constitutive relations, i.e., static and kinetic ones. They introduce a strain energy density and a kinetic energy density, respectively. Here we consider a three-dimensional elastic network made of three families of elastic fibers connected...
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Nonlinear model of a synchronous generator for analysis of more electric aircraft power systems
PublikacjaA nonlinear model for studying a variable-speed synchronous generator (SG) in more electric aircraft (MEA) power system has been developed. The saturation effects of the SG magnetic circuit have been considered. The model has been implemented in the Synopys/Saber simulation environment. The modelling language MAST has been used to elaborate the SG model. The model exhibit a network with the same number of external terminals/ports...
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RADIATION OF HIGH INTENSITY SOUND BY CIRCULAR DISC BY MEANS OF THE NUMERICAL METHOD
PublikacjaThe main goal of this paper is to find sound pressure distribution radiated by the circular piezoelectric disc that vibrates with the finite amplitude. There has been presented the pressure distribution close to the radiating surface. Also it is shown the sound pressure distribution in the 3D form. The mathematic modeling was carried out on the base of the nonlinear acoustic equation with the proper boundary condition. The axial...
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Nonlinear generation of non-acoustic modes by low-frequency sound in a vibrationally relaxing gas
PublikacjaTwo dynamic equations referring to a weakly nonlinear and weakly dispersive flow of a gas in which molecular vibrational relaxation takes place. are derived. The first one governs an excess temperature associated with the thermal mode, and the second one describes variations in vibrational energy. Both quantities refer to non-wave types of gas motion. These variations are caused by the nonlinear transfer of acoustic energy into...
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Nonlinear Fuzzy Control System for Dissolved Oxygen with Aeration System in Sequencing Batch Reactor
PublikacjaBiological processes at a wastewater treatment plant are complex, multivariable, time varying and nonlinear. Moreover, interactions between the components are very strong. Control of dissolved oxygen is one of most important task at the plant. The level of dissolved oxygen in aerobic tanks has significant influence on behaviour and activity of microorganisms at the plant. Air for aerated tanks is supplied by the aeration system...
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Nonlinear numerical simulation of earthquake-induced pounding between timber frame buildings
PublikacjaEarthquakes may induce serious dynamic loads acting on buildings, which can lead to damage or even destruction of the whole structure. In densely populated areas, it is quite common that buildings are located very close one to another which can result in pounding between them during ground motions. Due to the environmental awareness, multi-story timber frame buildings are gaining popularity and therefore there is a need to investigate...
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Standing Acoustic Waves and Relative Nonlinear Phenomena in a Vibrationally Relaxing Gas-Filled Resonator
PublikacjaStanding acoustic waves in one-dimensional resonator filled with vibrationally relaxing gas, are studied. Two regimes of excitation of molecular vibrational degrees of freedom are considered, equilibrium and nonequilibrium. The acoustic energy enlarges with time in the non-equilibrium regime and decreases otherwise before formation of discontinuity. After that, it decreases due to nonlinear absorption and tends to zero in equilibrium...
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Cross-talk modeling in coupled transmission lines terminated with nonlinear loads
PublikacjaW pracy przedstawiono przegląd dostępnych metod symulacji zjawiska przesłuchu kładąc szczegółny nacisk na efekty nieliniowości rzeczywistych obciążeń linii sygnałowych na płytach drukowanych. Wykorzystując metodę analizy opartą o szeregi Volterry przeanalizowano efekt przesłuchu w strukturze sprzężonych linii mikropaskowych obciążonych na wyjściu toru transmisyjnego diodą Schottky'ego z niską barierą potencjalu. Uzyskano bardzo...
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Quasilinearization methods for nonlinear differential-functional parabolic equations: unbounded case
PublikacjaRozważamy zagadnienie Cauchy'ego dla nieliniowych równań parabolicznych z zależnością funkcyjną. Przedstawiamy rezultaty dotyczące zbieżności metody quasilinearyzacji dla rozwiązań nieograniczonych.
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Geometrically nonlinear finite element simulation of smart piezolaminated plates and shells
PublikacjaW pracy zaproponowano powłokowy element skończony pozwalający na uwzględnienie efektu piezoelektrycznego. Element został wykorzystany w podejściu Lagrange'a, które wymaga starannego dobrania definicji wielkości mechanicznych i elektrycznych. Zależności przemieszczenie-odkształcenie zbudowano na bazie teorii małych odkształceń i umiarkowanych obrotów. Założono liniowy rozkład pól odkształceń i pola elektrycznego po grubości powłoki....
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First-order functional difference equations with nonlinear boundary value problems
PublikacjaDyskutowano 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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Nonlinear multipoint boundary value problems for second order differential equtions
PublikacjaPraca dotyczy problemow brzegowych dla rownan rozniczkowych rzedu drugiego z odchylonymi argumentami zaleznymi od rozwiazania. Podano warunki dostateczne na istnienie ekstremalnych rozwiazan. Poroblem istnienia jedynego rozwiazania tez byl przedmiotem badan. Podano dwa przyklady ilustrujace otrzymane wyniki.
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Weakly nonlinear dynamics of short acoustic waves in exponentially stratified gas
PublikacjaRozpatruje się dynamika krótkich (w porównywaniu z charakterystyczną skalą zmiany gęstości gazu atmosferycznego) fal akustycznych. Wyprowadzone nowe równanie ewolucyjne, które uwzględnia dyspersję i nieliniowy charakter propagacji tych fal. Porównuje sie liniowa i nieliniowa dynamika. Ilustracje propagacji, numeryczne wyliczione na podstawie nowych wzorów, są przedstawione. Indexed and abstracted (from vol. 32(1) 2007) in Science...
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Nonlinear modeling of traction transformer with coiled iron core for dynamic simulation
PublikacjaW referacie przedstawiono wyprowadzenie zastępczego modelu obwodowego transformatora trakcyjnego o rdzeniu zwijanym do analiz zachowania sie transformatora w układzie napedowym jednostki trakcyjnej. Model zakłada nieliniowa charakterystyke magnesowania B-H i anizotropowe właściwosci magnetyczne i elektryczne zwijanego rdzenia. Wyprowadzenie modelu oparto na metodzie energetycznej Lagrange'a. Uzwojenia zostały zamodelowanie jako...
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Artificial-Neural-Network-Based Sensorless Nonlinear Control of Induction Motors
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Speed sensorless nonlinear control of induction motor in the field weakening region
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Existence results to delay fractional differential equations with nonlinear boundary conditions
PublikacjaPraca dotyczy problemów brzegowych dla ułamkowych równań różniczkowych z opóźnionym argumentem. Podano warunki dostateczne na istnienie rozwiązań ekstremalnych takich zagadnień.
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Novel Nonlinear High Order Technologies for Damage Diagnosis of Complex Assets
PublikacjaFor the first time worldwide, innovative techniques, generic non-linear higher-order unnormalized cross-correlations of spectral moduli, for the diagnosis of complex assets, are proposed. The normalization of the proposed techniques is based on the absolute central moments, that have been proposed and widely investigated in mathematical works. The existing higher-order, crosscovariances of complex spectral components are not sufficiently...
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Implicit difference methods for nonlinear first order partial differential equations
PublikacjaW 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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PbGa2GeS6 crystal as a novel nonlinear optical material: Band structure aspects
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Functionalized mesoporous silica thin films as a tunable nonlinear optical material
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On Nonlinear Volterra Integral Equations With State Dependent Delays in Several Variables
PublikacjaW pracy badane jest istnienie i jednoznaczność rozwiązań nieliniowego równania całkowego typu Volterry z opóźnionym argumentem zależnym od funkcji niewiadomej wielu zmiennych. Poszukiwane są ciągłe rozwiązania lipschitzowskie. Rozwiązania są poszukiwane metodą porównawczą z zastosowaniem twierdzenia Banacha o punkcie stałym.
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Finite difference approximations for nonlinear first order partial differential equations
PublikacjaKlasyczne rozwiązania nieliniowych równań różniczkowych o pochodnych cząst-kowych pierwszego rzędu są aproksymowane za pomocą równań quasiliniowych uk-ładów równań różniczkowych. Dowód zbieżności wykorzystuje metody porównawcze
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Adaptive fuzzy modelling and control for discrete-time nonlinear uncertain systems
PublikacjaReferat przedstawia metodę adaptacyjnego rozmytego modelowania i sterowania dla nieliniowego systemu dyskretnego z niepewnością. Proponowana metoda adaptacyjna składa się z dwóch części: rozmyte modelowanie on-line z zastosowaniem systemu Takagi - Sugeno (T-S) oraz sterowanie adaptacyjne z modelem referencyjnym. Model rozmyty T-S posiada samoorganizującą się strukturę, tzn. reguły rozmyte mogą być dodawane, zamieniane lub usuwane...
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Artificial Neural Network-Based Sensorless Nonlinear Control Of Induction Motors
PublikacjaW niniejszym artykule przedstawiono strukturę sztucznej sieci neuronowej służącej do korygowania działania układu estymacji prędkości kątowej wirnika. Odtworzona prędkość kątowa wirnika zostały wykorzystane w bezczujnikowym układzie sterowania silnikiem indukcyjnym pracującym w zamkniętej pętli sprzężenia prędkościowego.Przedstawiono wyniki badań eksperymentalnych z silnikiem o mocy 1,1kW.
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Pounding of structures during earthquakes modelled by nonlinear viscoelastic impact element.
PublikacjaAnalizowano zderzenia konstrukcji budowlanych podczas trzęsień ziemi wykorzystując model lepkosprężysty siły zderzenia. W analizie, zachowanie konstrukcji o różnych własnościach dynamicznych symulowane jest modelem dyskretnym o skupionych masach. wyniki badań pokazują, iż zderzenie może prowadzić do znacznego wzrostu odpowiedzi konstrukcji mniej sztywnej i lżejszej.
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Investigation of influence of space mopdes interaction on nonlinear dynamics of sound beams
PublikacjaOperatory rzutu na mody są zdefiniowane w dynamice płynów trójwymiarowych. Zostały wyprowadzone równania ewolucyjne. Rezultaty obliczeń numerycznych przedstawione.
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Nonlinear impedance in oxide glasses containing single and mixed alkali ions
PublikacjaThe aim of the present was to find more clues on the nonlinearities in impedance of oxide glasses. The first family of researched glasses has a composition of FeO-P2O5-Na2O. Oxide glasses containing iron and alkali are well known for a very low alkali ion mobility and may be considered purely polaron conducting. These glasses show no detectable nonlinearities in the impedance spectra. The second was a family of ionic conducting...
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Wild oscillations in a nonlinear neuron model with resets: (II) Mixed-mode oscillations
PublikacjaThis work continues the analysis of complex dynamics in a class of bidimensional nonlinear hybrid dynamical systems with resets modeling neuronal voltage dynamics with adaptation and spike emission. We show that these models can generically display a form of mixed-mode oscillations (MMOs), which are trajectories featuring an alternation of small oscillations with spikes or bursts (multiple consecutive spikes). The mechanism by...
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Measurement system for nonlinear surface spectroscopy by atomic force microscopy for corrosion processes monitoring
PublikacjaIn addition to traditional imaging the surface, atomic force microscopy (AFM) enables wide variety of additional measurements. One of them is higher harmonic imaging. In tapping mode the nonlinear contact between tip and specimen results in higher frequency vibrations. More information available from the higher harmonics analysis proves to be helpful for more detailed imaging. Such visualization is especially useful for heterogeneous...
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Robust Parameter Estimation and Output Prediction for Reactive Carrier-Load Nonlinear Dynamic Networks
PublikacjaIn 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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Comparison of Two Nonlinear Predictive Control Algorithms for Dissolved Oxygen Tracking Problem at WWTP
PublikacjaThe wastewater treatment plant is classified as a complex system, due to its nonlinear dynamics, large uncertainty of disturbance inputs, multiple time scales in the internal process dynamics, and multivariable structure. The aeration process, in turn, is an important and expensive part of wastewater treatment plant operation. All operating parameters of the aeration in biological processes are to be precisely controlled to provide...
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Boundary problems for fractional differential equations
PublikacjaIn this paper, the existence of solutions of fractional differential equations with nonlinear boundary conditions is investigated. The monotone iterative method combined with lower and upper solutions is applied. Fractional differential inequalities are also discussed. Two examples are added to illustrate the results.
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Novel hierarchical nonlinear control algorithm to improve dissolved oxygen control in biological WWTP
PublikacjaWastewater treatment is a problem known to humankind for centuries. The quality of treated sewage determines the condition of reservoirs around the world. Control of such a complex and nonlinear system as a wastewater treatment plant requires thorough knowledge of the process. The paper presents a hierarchical control system of a Sequencing Batch Reactor (SBR) in Wastewater Treatment Plant (WWTP) taking into account a model based...
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Modal FEM Analysis of Ferrite Resonant Structures
PublikacjaThe finite-element method (FEM) is applied for modal analysis of ferrite-loaded spherical resonators. To improve the efficiency of the numerical calculations, the body-of-revolution (BOR) technique is utilized. Due to the frequency-dependent ferrite permeability, FEM leads to a nonlinear eigenvalue problem that is challenging to solve. To this end, Beyn’s method is proposed. The effectiveness of the proposed approach is confirmed...
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The influence of azide and imidazole on the properties of Mn- and Cd-based networks: conductivity and nonlinear phenomena
PublikacjaWe report a study on a family of four new Mn- and Cd-azide-imidazolate-based compounds with various crystal architectures. Notably, three of these compounds display noncentrosymmetric crystal arrangements at room temperature, a rare phenomenon in hybrid organic–inorganic materials. Both nonlinear optical (NLO) and electrical phenomena in these compounds are observed. The NLO processes include second and third harmonic generation,...
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Accuracy of Trajectory Tracking Based on Nonlinear Guidance Logic for Hydrographic Unmanned Surface Vessels
PublikacjaA new trend in recent years for hydrographic measurement in water bodies is the use of unmanned surface vehicles (USVs). In the process of navigation by USVs, it is particularly important to control position precisely on the measuring profile. Precise navigation with respect to the measuring profile avoids registration of redundant data and thus saves time and survey costs. This article addresses the issue of precise navigation...
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Nonlinear secondary arc model use for evaluation of single pole auto-reclosing effectiveness
PublikacjaPurpose – The purpose of this paper is to discuss two evaluation methods of single pole autoreclosing process effectiveness in HV transmission lines. Secondary arc current and recovery voltage results obtained by load flow calculation are compared to the results obtained by the time domain simulations. Moreover, a nonlinear secondary arc implementation is presented. Design/methodology/approach – A computer simulation studies were...
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Fluid–solid interaction on a thin platelet with high-velocity flow: vibration modelling and experiment
PublikacjaThe paper concerns the nonlinear behaviour of a thin platelet that is streamlined in an aerodynamic tunnel. The air velocity in the aerodynamic tunnel was at 858.9 km/h or 0.7 Ma (Ma—Mach number is a dimensionless quantity in fluid dynamics representing the ratio of flow velocity past a boundary to the local speed of sound). This experiment was numerically simulated using FSI (fluid–solid interaction) tools, namely the coupling...
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Novel Vision Monitoring Method Based on Multi Light Points for Space-Time Analysis of Overhead Contact Line Displacements
PublikacjaThe article presents an innovative vision monitoring method of overhead contact line (OCL) displacement, which utilizes a set of LED light points installed along it. A light point is an, LED fed from a battery. Displacements of the LED points, recorded by a camera, are interpreted as a change of OCL shape in time and space. The vision system comprises a camera, properly situated with respect to the OCL, which is capable of capturing...
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Nonlinear Impedance as Possible Result of Ion-Polaron Interaction in Cu2O-Al2O3-SiO2 Glass
PublikacjaNonlinear a.c. impedance measurements were performed in Cu2O-Al2O3-SiO2 glass in wide frequency range. The obtained results shows that a large nonlinearity in the impedance signal is observed at moderate electric fields of an order 1V/mm. The contents of the third harmonics reaches about 10% and strongly depends on temperature and frequency. The investigated glass exhibits mixed electronic-ionic conductivity. Electronic conduction...
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Mechatronic design o strongly nonlinear systems on a basis of three wheeled mobile platform
PublikacjaRemarkable grow in demand both of mobile platform operability performance and reduction of project leading time development encourage to apply modern algorithms and reliable engineering tools for the design process. The paper discusses the mechatronic design applied for the surveillance system based on the energy performance index algorithm. The exploited mechatronic techniques i.e. virtual prototyping, Hardware-In-the-Loop Simulation...
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Unusual dynamics and nonlinear thermal self-focusing of initially focused magnetoacoustic beams in a plasma
PublikacjaUnusual thermal self-focusing of two-dimensional beams in plasma which axis is parallel to the equilibrium straight magnetic field is considered. The equi- librium parameters of plasma determine scenario of a beam divergence (usual or unusual) which is stronger as compared with a flow without magnetic field. Nonlinear thermal self-action of a magnetosonic beam behaves differently in the ordinary and unusual cases. Damping of wave...