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Wyszukujesz frazę "Nonlinear Model" wg kryterium: Temat


Tytuł:
“Noise” in climatologically driven ocean models with different grid resolution
Autorzy:
Tang, S.
von Storch, H.
Chen, X.
Zhang, M.
Powiązania:
https://bibliotekanauki.pl/articles/48986.pdf
Data publikacji:
2019
Wydawca:
Polska Akademia Nauk. Instytut Oceanologii PAN
Tematy:
climate system
noise
nonlinear model
high-dimensional nonlinear model
macroturbulence
spatial distribution
daily variation
South China Sea
Źródło:
Oceanologia; 2019, 61, 3
0078-3234
Pojawia się w:
Oceanologia
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
A 24 GHz PHEMT-based oscillator
Autorzy:
Lewandowski, A.
Kompa, G.
Mwema, W.
Wiatr, W.
Powiązania:
https://bibliotekanauki.pl/articles/309225.pdf
Data publikacji:
2003
Wydawca:
Instytut Łączności - Państwowy Instytut Badawczy
Tematy:
generator mikrofalowy
opór ujemny
microwave oscillator
oscillator design method
negative resistance
describing function
nonlinear PHEMT model
microstrip components models
Opis:
We present a systematic nonlinear procedure for designing microwave oscillators utilising a nonlinear PHEMT model, the negative resistance approach and the describing function concept. The procedure is applied in the design of a 24 GHz oscillator, which is then realised in hybrid technology. Measurement results show - 6% shift in the frequency but an acceptable agreement in the output power. A detailed analysis shows that the frequency shift arises mainly from inadequate CAD models in the K band, for the microstrip components employed in our design.
Źródło:
Journal of Telecommunications and Information Technology; 2003, 1; 15-19
1509-4553
1899-8852
Pojawia się w:
Journal of Telecommunications and Information Technology
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
A computationally efficient stable dual-mode type nonlinear predictive control algorithm
Autorzy:
Ławryńczuk, M.
Tadej, W.
Powiązania:
https://bibliotekanauki.pl/articles/971003.pdf
Data publikacji:
2008
Wydawca:
Polska Akademia Nauk. Instytut Badań Systemowych PAN
Tematy:
linearyzacja
optymalizacja
stabilność
nonlinear model predictive control
dual-mode model predictive control
process control
linearisation
optimisation
quadratic programming
stability
constraints
terminal set
Opis:
This paper describes a computationally efficient (sub-optimal) nonlinear predictive control algorithm. The algorithm uses a modified dual-mode approach which guarantees closed-loop stability. In order to reduce the computational burden, instead of online nonlinear optimisation used in the classical dual-mode control scheme, a nonlinear model of the plant is linearised on-line and a quadratic programming problem is solved. Calculation of the terminal set and implementation steps of the algorithm are detailed, especially for input-output models, which are widely used in practice.
Źródło:
Control and Cybernetics; 2008, 37, 1; 99-132
0324-8569
Pojawia się w:
Control and Cybernetics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
A discrete model for geometrically nonlinear free and forced vibrations of stepped and continuously segmented Euler-Bernoulli AFG beams (SAFGB) carrying point masses
Autorzy:
Moukhliss, Anass
Rahmouni, Abdellatif
Bouksour, Othman
Benamar, Rhali
Powiązania:
https://bibliotekanauki.pl/articles/2146732.pdf
Data publikacji:
2022
Wydawca:
Polska Akademia Nauk. Polskie Towarzystwo Diagnostyki Technicznej PAN
Tematy:
discrete model
stepped beam
free non-linear vibration
forced nonlinear vibration
AFG beam
point mass
model dyskretny
belka o skokowo zmiennym przekroju
drgania swobodne
drgania wymuszone
drgania nieliniowe
Opis:
A discrete model is applied to handle the geometrically nonlinear free and forced vibrations of beams consisting of several different segments whose mechanical characteristics vary in the length direction and contain multiple point masses located at different positions. The beam is presented by an N degree of freedom system (N-Dof). An approach based on Hamilton's principle and spectral analysis is applied, leading to a nonlinear algebraic system. A change of basis from the displacement basis to the modal basis has been performed. The mechanical behavior of the N-Dof system is described in terms of the mass tensor mij, the linear stiffness tensor kij, and the nonlinear stiffness tensor bijkl. The nonlinear vibration frequencies as functions of the amplitude of the associated vibrations in the free and forced cases are predicted using the single mode approach. Once the formulation is established, several applications are considered in this study. Different parameters control the frequency-amplitude dependence curve: the laws that describe the variation of the mechanical properties along the beam length, the number of added masses, the magnitude of excitation force, and so on. Comparisons are made to show the reliability and applicability of this model to non-uniform and non-homogeneous beams in free and forced cases.
Źródło:
Diagnostyka; 2022, 23, 4; art no 2022401
1641-6414
2449-5220
Pojawia się w:
Diagnostyka
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
A discrete model for nonlinear vibrations of a simply supported cracked beams resting on elastic foundations
Autorzy:
Khnaijar, A.
Benamar, R.
Powiązania:
https://bibliotekanauki.pl/articles/328710.pdf
Data publikacji:
2017
Wydawca:
Polska Akademia Nauk. Polskie Towarzystwo Diagnostyki Technicznej PAN
Tematy:
nonlinear
discrete
beam
Winkler foundation
crack
vibration
drgania nieliniowe
podłoże Winklera
belka
pęknięcie
model
Opis:
The present paper introduces a discrete physical model to approach the problem of nonlinear vibrations of cracked beams resting on elastic foundations. It consists of a beam made of several small bars, evenly spaced, connected by spiral springs, presenting the beam bending stiffness. The crack is modeled by a spiral spring with a reduced stiffness and the Winkler soil stiffness is modeled using linear vertical springs. Concentrated masses, presenting the inertia of the beam, are located at the bar ends. The nonlinear effect, due to the axial forces in the bars resulting from the change in their length, is presented by longitudinal springs. This model has the advantage of simplifying parametric studies, because of its discrete nature, allowing any modification in the mass and the stiffness matrices, and in the nonlinearity tensor, to be made separately. After establishing the model, various practical applications are performed without the need of going through all the formulation again. Numerical linear and nonlinear results are given, corresponding to a cracked simply supported beam.
Źródło:
Diagnostyka; 2017, 18, 3; 39-46
1641-6414
2449-5220
Pojawia się w:
Diagnostyka
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
A locally modified single-phase model for analyzing magnetohydrodynamic boundary layer flow and heat transfer of nanofluids over a nonlinearly stretching sheet with chemical reaction
Autorzy:
Akbarzadeh, P.
Powiązania:
https://bibliotekanauki.pl/articles/949119.pdf
Data publikacji:
2018
Wydawca:
Polskie Towarzystwo Mechaniki Teoretycznej i Stosowanej
Tematy:
nanofluid
magnetohydrodynamic
nonlinear stretching sheet
similarity transformation
locally modified single-phase model
Opis:
The problem of boundary layer flow and heat transfer of nanofluids over nonlinear stretching of a flat sheet in the presence of a magnetic field and chemical reaction is investigated numerically. In this paper, a new locally modified single-phase model for the analysis is introduced. In this model, the effective viscosity, density and thermal conductivity of the solid-liquid mixtures (nanofluids) which are commonly utilized in the homogenous single-phase model, are locally combined with the prevalent single-phase model. Similarity transformation is used to convert the governing equations into three coupled nonlinear ordinary differential equations. These equations depend on five local functions of the nanoparticle volume fraction viz., local viscosity ratio, magnetic, Prandtl, Brownian motion and thermophoresis functions. The equations are solved using Newton’s method and a block tridiagonal matrix solver. The results are compared to the prevalent single-phase model. In addition, the effect of important governing parameters on the velocity, temperature, volume fraction distribution and the heat and mass transfer rates are examined.
Źródło:
Journal of Theoretical and Applied Mechanics; 2018, 56, 1; 81-94
1429-2955
Pojawia się w:
Journal of Theoretical and Applied Mechanics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
A new predictive filter for nonlinear alignment model of stationary MEMS inertial sensors
Autorzy:
Alhassan, Hassan Majed
Ghahremani, Nemat Allah
Powiązania:
https://bibliotekanauki.pl/articles/2052163.pdf
Data publikacji:
2021
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
predictive filter
nonlinear alignment
model error
optimization
MEMS inertial sensors
Opis:
This paper proposes a new approach called the Predictive Kalman Filter (PKF) which predicts and compensates model errors of inertial sensors to improve the accuracy of static alignment without the use of external assistance. The uncertain model error is the main problem in the field as the Micro Electro Mechanical System (MEMS) inertial sensors have bias which change over time, and these errors are not all observable. The proposed filter determines an optimal equivalent model error by minimizing a quadratic penalty function without augmenting the system state space. The optimization procedure enables the filter to decrease both model uncertainty and external disturbances. The paper first presents the complete formulation of the proposed filter. Then, a nonlinear alignment model with a large misalignment angle is considered. Experimental results demonstrate that the new method improves the accuracy and rapidness of the alignment process as the convergence time is reduced from 550 s to 50 s, and the azimuth misalignment angle correctness is decreased from 52′′ ± 47′′ to 4′′ ± 0.02′′.
Źródło:
Metrology and Measurement Systems; 2021, 28, 4; 673-691
0860-8229
Pojawia się w:
Metrology and Measurement Systems
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
A nonlinear analysis method for arch-shaped shell roofs made of cold-formed steel profiles
Autorzy:
Zhdanov, D.
Ulasevich, V.
Powiązania:
https://bibliotekanauki.pl/articles/402655.pdf
Data publikacji:
2016
Wydawca:
Politechnika Białostocka. Oficyna Wydawnicza Politechniki Białostockiej
Tematy:
arch-shaped shell roof
cold-formed steel profiles
nonlinear analysis method
action effects model
structural resistance model
szkielet dachu w kształcie łuku
profile stalowe formowane na zimno
metoda analizy nieliniowej
efekty działanie modelu
odporność modelu strukturalnego
Opis:
The paper deals with the problem of static structural analysis of shallow arch-shaped shell roofs assembled from curved cold-formed steel profiles. A nonlinear analysis procedure has been proposed to estimate the stress-strain state of such roof structures. It is based on two interrelated analysis models developed for the purpose – namely, an action effects model used for the static analysis of deformational behaviour of shallow arch-shaped structural systems, and a resistance model, for strength analysis of cold-formed steel profiles.
Źródło:
Budownictwo i Inżynieria Środowiska; 2016, 7, 3; 187-191
2081-3279
Pojawia się w:
Budownictwo i Inżynieria Środowiska
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
A nonlinear statistical approach for damping uncertainty propagation in structural dynamics
Nieliniowe modelowanie statystyczne niepewności tłumienia w dynamice konstrukcyjnej
Autorzy:
Tiliouine, B.
Chemali, B.
Powiązania:
https://bibliotekanauki.pl/articles/230868.pdf
Data publikacji:
2016
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
dynamika konstrukcji
niepewność
odpowiedź dynamiczna
symulacja Monte Carlo
model nieliniowy
model statystyczny
structure dynamics
uncertainty
dynamic response
Monte Carlo simulation
nonlinear model
statistical model
Opis:
The object of the present study is to investigate the influence of damping uncertainty and statistical correlation on the dynamic response of structures with random damping parameters in the neighbourhood of a resonant frequency. A Non-Linear Statistical model (NLSM) is successfully demonstrated to predict the probabilistic response of an industrial building structure with correlated random damping. A practical computational technique to generate first and second-order sensitivity derivatives is presented and the validity of the predicted statistical moments is checked by traditional Monte Carlo simulation. Simulation results show the effectiveness of the NLSM to estimate uncertainty propagation in structural dynamics. In addition, it is demonstrated that the uncertainty in damping indeed influences the system response with the effects being more pronounced for lightly damped structures, higher variability and higher statistical correlation of damping parameters.
Nieliniowy Model Statystyczny (NLSM) jest opracowany, aby skutecznie rozpowszechniać niepewność tłumienia w analizach dynamicznych, w celu przewidywania statystyki drugiego rzędu dla probabilistycznej odpowiedzi konstrukcji ze skorelowanymi parametrami tłumienia. Waga tłumienia losowego ze skorelowanymi parametrami oraz ich wpływ na wrażliwość szczytowej odpowiedzi konstrukcyjnej, omawiane są w świetle znaczących zakresów niepewności tłumienia oraz współczynników korelacji. Dodatkowo, wpływ korelacji statystycznej tłumienia na granice przybliżenia Liniowego Modelu Statystycznego (LSM) oraz na NLSM badany jest za pomocą Symulacji Monte Carlo.
Źródło:
Archives of Civil Engineering; 2016, 62, 1; 11-24
1230-2945
Pojawia się w:
Archives of Civil Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
A numerically efficient fuzzy MPC algorithm with fast generation of the control signal
Autorzy:
Marusak, Piotr M.
Powiązania:
https://bibliotekanauki.pl/articles/1838187.pdf
Data publikacji:
2021
Wydawca:
Uniwersytet Zielonogórski. Oficyna Wydawnicza
Tematy:
model predictive control
fuzzy system
fuzzy control
nonlinear control
sterowanie predykcyjne
system rozmyty
sterowanie rozmyte
sterowanie nieliniowe
Opis:
Model predictive control (MPC) algorithms are widely used in practical applications. They are usually formulated as optimization problems. If a model used for prediction is linear (or linearized on-line), then the optimization problem is a standard, i.e., quadratic, one. Otherwise, it is a nonlinear, in general, nonconvex optimization problem. In the latter case, numerical problems may occur during solving this problem, and the time needed to calculate control signals cannot be determined. Therefore, approaches based on linear or linearized models are preferred in practical applications. A novel, fuzzy, numerically efficient MPC algorithm is proposed in the paper. It can offer better performance than the algorithms based on linear models, and very close to that of the algorithms based on nonlinear optimization. Its main advantage is the short time needed to calculate the control value at each sampling instant compared with optimization-based numerical algorithms; it is a combination of analytical and numerical versions of MPC algorithms. The efficiency of the proposed approach is demonstrated using control systems of two nonlinear control plants: the first one is a chemical CSTR reactor with a van de Vusse reaction, and the second one is a pH reactor.
Źródło:
International Journal of Applied Mathematics and Computer Science; 2021, 31, 1; 59-71
1641-876X
2083-8492
Pojawia się w:
International Journal of Applied Mathematics and Computer Science
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
A robust model free controller for a class of SISO nonaffine nonlinear systems: Application to an electropneumatic actuator
Autorzy:
Boubakir, Ahsene
Labiod, Salim
Boudjema, Fares
Powiązania:
https://bibliotekanauki.pl/articles/229193.pdf
Data publikacji:
2019
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
dynamic inversion control
model free controller
nonaffine nonlinear systems
singular perturbation theory
Opis:
This paper presents a robust model free controller (RMFC) for a class of uncertain continuous-time single-input single-output (SISO) minimum-phase nonaffine-in-control systems. Firstly, the existence of an unknown dynamic inversion controller that can achieve control objectives is demonstrated. Afterwards, a fast approximator is designed to estimate as best as possible this dynamic inversion controller. The proposed robust model free controller is an equivalent realization of the designed fast approximator. The perturbation theory and Tikhonov’s theorem are used to analyze the stability of the overall closed-loop system. The performance of the developped controller are verified experimentally in the position control of a pneumatic actuator system.
Źródło:
Archives of Control Sciences; 2019, 29, 3; 437-458
1230-2384
Pojawia się w:
Archives of Control Sciences
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
A Study on the Low Frequency Transients in Power Transformers and Some Protection-Related Issues
Autorzy:
Saied, M. M.
Powiązania:
https://bibliotekanauki.pl/articles/1203944.pdf
Data publikacji:
2014
Wydawca:
Akademia Górniczo-Hutnicza im. Stanisława Staszica w Krakowie
Tematy:
transformer cores
inrush current
protection
transients
modeling
equivalent circuit
low frequency
nonlinear model
simulation
Opis:
This paper presents typical results for the non-linear low frequency transients following the energization of power transformers. The three operating conditions of no-load, full-load and internal faults are considered. A direct analytical procedure is applied for solving the corresponding set of differential equations describing the transformers equivalent circuit. The core representation is based on the use of curve fitting applied to their magnetization curves. The results include plots versus time for the supply current, the core flux, the magnetizing current as well as the internal induced voltage. Moreover, graphs for the hysteresis loops relating the instantaneous values of both the excitation current and the core flux are given. An approach is also presented for the numerical determination of the amplitudes of the different harmonics existing in any of these signals utilizing the corresponding equidistant samples. As examples, the DC offset as well as harmonics up to the fourth order are considered. It is shown that several useful features can be extracted from the results in both the time and harmonic domains that can assist in differentiating between overcurrents resulting from short-circuits or inrush phenomena.
Źródło:
Electrical Power Quality and Utilisation. Journal; 2014, 17, 2; 9-16
1896-4672
Pojawia się w:
Electrical Power Quality and Utilisation. Journal
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Active fault tolerant control of nonlinear systems: the cart-pole example
Autorzy:
Bonfe, M.
Castaldi, P.
Mimmo, N.
Simani, S.
Powiązania:
https://bibliotekanauki.pl/articles/907604.pdf
Data publikacji:
2011
Wydawca:
Uniwersytet Zielonogórski. Oficyna Wydawnicza
Tematy:
detekcja uszkodzeń
lokalizacja uszkodzeń
filtracja nieliniowa
sterowanie tolerujące uszkodzenia
fault detection
fault isolation
nonlinear filter
nonlinear geometric approach
fault tolerant control
cart pole nonlinear model
Opis:
This paper describes the design of fault diagnosis and active fault tolerant control schemes that can be developed for nonlinear systems. The methodology is based on a fault detection and diagnosis procedure relying on adaptive filters designed via the nonlinear geometric approach, which allows obtaining the disturbance de-coupling property. The controller reconfiguration exploits directly the on-line estimate of the fault signal. The classical model of an inverted pendulum on a cart is considered as an application example, in order to highlight the complete design procedure, including the mathematical aspects of the nonlinear disturbance de-coupling method based on the nonlinear differential geometry, as well as the feasibility and efficiency of the proposed approach. Extensive simulations of the benchmark process and Monte Carlo analysis are practical tools for assessing experimentally the robustness and stability properties of the developed fault tolerant control scheme, in the presence of modelling and measurement errors. The fault tolerant control method is also compared with a different approach relying on sliding mode control, in order to evaluate benefits and drawbacks of both techniques. This comparison highlights that the proposed design methodology can constitute a reliable and robust approach for application to real nonlinear processes.
Źródło:
International Journal of Applied Mathematics and Computer Science; 2011, 21, 3; 441-455
1641-876X
2083-8492
Pojawia się w:
International Journal of Applied Mathematics and Computer Science
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Active vibration control of Terfenol-D rod of giant magnetostrictive actuator with nonlinear constitutive relations
Aktywne sterowanie drganiami w wielkim aktuatorze magnetostrykcyjnym z rdzeniem typu Terfenol-D przy uwzględnieniu nieliniowych równań konstytutywnych
Autorzy:
Zhou, H-M.
Zhou, Y-H.
Zheng, X. J.
Powiązania:
https://bibliotekanauki.pl/articles/281451.pdf
Data publikacji:
2007
Wydawca:
Polskie Towarzystwo Mechaniki Teoretycznej i Stosowanej
Tematy:
aktuator wielki magnetostrykcyjny
nieliniowe równania konstytutywne
analiza tłumienia drgań
giant magnetostrictive actuators
nonlinear constitutive model
negative feedback control law
active control of vibration suppression
Opis:
This paper presents a numerical simulation of active vibration control of the Terfenol-D rad of a giant magnetostrictive transducer with nonlinear constitutive relations. In this control system, the goal is to suppress vibration of the displacement at the free end of the rod that is usually connected with a platform. Due to the inherent nonlinear relation among the applied magnetic field, pre-stress, and strain, the extension of the rod is also nonlinear relative to the external applications. Having an analytieal nonlinear constitutive model of the Terfenol-D rod proposed by the last author of this paper and the finite element method employed in the deformation analysis, we propose a numerical code to simulate the dynamic behavior of the control system when the negative displacement and velocity control law is utilized to feed back the signals to the actuator. The simulation results display that this control is more effective that other existing control algorithms based on linear constitutive models.
W pracy zaprezentowano symulacje numeryczne aktywnego sterowania za pomocą wielkiego aktuatora magnetostrykcyjnego zawierającego rdzeń wykonany z Terfenolu-D opisanego nieliniowymi zależnościami konstytutywnymi. Celem rozważań jest analiza tłumienia drgań swobodnego końca pręta, zwykle łączonego z platformą. Wydłużenie pręta jest opisane nieliniowym równaniem z powodu nieliniowych relacji pomiędzy przykładanym polem magnetycznym, naprężeniami wstępnymi oraz odkształceniami. Po sformułowaniu przez ostatniego Autora niniejszej pracy modelu pręta z Terfenolu-D oraz zastosowaniu metody elementów skończonych, wprowadzono procedurę numeryczną o symulacji dynamiki układu sterowania z ujemnym sprzężeniem zwrotnym ze względu na przemieszczenie i prędkość końca aktuatora. Wyniki badań pokazały, że tego typu sterowanie staje się bardziej efektywne niż inne strategie redukcji drgań oparte na modelach liniowych.
Źródło:
Journal of Theoretical and Applied Mechanics; 2007, 45, 4; 953-967
1429-2955
Pojawia się w:
Journal of Theoretical and Applied Mechanics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Actuator fault tolerance in control systems with predictive constrained set-point optimizers
Autorzy:
Marusak, P. M.
Tatjewski, P.
Powiązania:
https://bibliotekanauki.pl/articles/929879.pdf
Data publikacji:
2008
Wydawca:
Uniwersytet Zielonogórski. Oficyna Wydawnicza
Tematy:
sterowanie odporne na błędy
sterowanie predykcyjne
optymalizacja
system nieliniowy
fault tolerant control
model predictive control
set-point optimization
nonlinear system
Opis:
Mechanisms of fault tolerance to actuator faults in a control structure with a predictive constrained set-point optimizer are proposed. The structure considered consists of a basic feedback control layer and a local supervisory set-point optimizer which executes as frequently as the feedback controllers do with the aim to recalculate the set-points both for constraint feasibility and economic performance. The main goal of the presented reconfiguration mechanisms activated in response to an actuator blockade is to continue the operation of the control system with the fault, until it is fixed. This may be even long-term, if additional manipulated variables are available. The mechanisms are relatively simple and consist in the reconfiguration of the model structure and the introduction of appropriate constraints into the optimization problem of the optimizer, thus not affecting the numerical effectiveness. Simulation results of the presented control system for a multivariable plant are provided, illustrating the efficiency of the proposed approach.
Źródło:
International Journal of Applied Mathematics and Computer Science; 2008, 18, 4; 539-551
1641-876X
2083-8492
Pojawia się w:
International Journal of Applied Mathematics and Computer Science
Dostawca treści:
Biblioteka Nauki
Artykuł

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