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Tytuł:
Forecasting models for chaotic fractional-order oscillators using neural networks
Autorzy:
Bingi, Kishore
Prusty, B Rajanarayan
Powiązania:
https://bibliotekanauki.pl/articles/2055150.pdf
Data publikacji:
2021
Wydawca:
Uniwersytet Zielonogórski. Oficyna Wydawnicza
Tematy:
chaotic oscillators
data driven forecasting
fractional order system
model free analysis
neural network
time series prediction
oscylator chaotyczny
układ rzędu ułamkowego
sieć neuronowa
prognozowanie szeregów czasowych
Opis:
This paper proposes novel forecasting models for fractional-order chaotic oscillators, such as Duffing’s, Van der Pol’s, Tamaševičius’s and Chua’s, using feedforward neural networks. The models predict a change in the state values which bears a weighted relationship with the oscillator states. Such an arrangement is a suitable candidate model for out-of-sample forecasting of system states. The proposed neural network-assisted weighted model is applied to the above oscillators. The improved out-of-sample forecasting results of the proposed modeling strategy compared with the literature are comprehensively analyzed. The proposed models corresponding to the optimal weights result in the least mean square error (MSE) for all the system states. Further, the MSE for the proposed model is less in most of the oscillators compared with the one reported in the literature. The proposed prediction model’s out-of-sample forecasting plots show the best tracking ability to approximate future state values.
Źródło:
International Journal of Applied Mathematics and Computer Science; 2021, 31, 3; 387--398
1641-876X
2083-8492
Pojawia się w:
International Journal of Applied Mathematics and Computer Science
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Free vibration analysis of FGM stepped nanostructures using nonlocal dynamic stiffness model
Autorzy:
Lien, Tran Van
Duc, Ngo Trong
Dinh, Tran Binh
Dat, Pham Tuan
Powiązania:
https://bibliotekanauki.pl/articles/2086972.pdf
Data publikacji:
2022
Wydawca:
Polskie Towarzystwo Mechaniki Teoretycznej i Stosowanej
Tematy:
nonlocal
DSM
FGM
nanostructure
nondimensional frequency
Opis:
A nonlocal Dynamic Stiffness Model (DSM) for free vibration analysis of Functionally Graded Material (FGM) stepped nanostructures based on the Nonlocal Elastic Theory (NET) is proposed. An exact solution to the equation of motion of a nanobeam element according to the Timoshenko beam theory, NET, and taking into account position of the neutral axis is constructed. Nondimensional frequencies and mode shapes of complete FGM stepped nanostructures are easily obtained using the nonlocal DSM. Numerical results are presented to show significance of the material distribution profile, nonlocal effect, and boundary conditions on free vibration of nanostructures.
Źródło:
Journal of Theoretical and Applied Mechanics; 2022, 60, 2; 279--292
1429-2955
Pojawia się w:
Journal of Theoretical and Applied Mechanics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Computational model of Collective Intelligence for meta-level analysis and prediction of free or quasi-free market economy
Autorzy:
Szuba, T.
Szydło, S.
Skrzyński, P.
Powiązania:
https://bibliotekanauki.pl/articles/1203941.pdf
Data publikacji:
2012
Wydawca:
Akademia Górniczo-Hutnicza im. Stanisława Staszica w Krakowie. Wydawnictwo AGH
Tematy:
collective intelligence
computational model
free market
quasi-free market
economics
human behavior
simulation model
Opis:
This paper encourages the use of a computational model of Collective Intelligence as a major (meta-level) tool to analyze and predict behavior of socio-economical systems like free (or quasi-free) markets are. Researchers are aware, that economics is a study of human behavior, but lack of a proper formal tool has shifted research in economics into the language of money, production, consumption, etc. From an economic point of view, when analyzing free (quasi-free) markets, more important is group behavior than individual behavior because they result in changes of market indexes. Group behavior leads in specific cases to the emergence of "group intelligence" with the most famous case named "A. Smith invisible hand of market". A computational model of Collective Intelligence allows for the formal extraction of the "system of inference processes" which run in an unconscious way in socio-economic structures. The construction of a proper formal and simulation model of such Collective Intelligence inferences allows us to take an attempt to predict outcomes in terms of economical results. The paper will present a formal basis, methodology of constructing Collective Intelligence systems for given socio-economic structures.
Źródło:
Decision Making in Manufacturing and Services; 2012, 6, 1-2; 41-51
1896-8325
2300-7087
Pojawia się w:
Decision Making in Manufacturing and Services
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Simulation tests of the method for determining a CAD model of free-form surface deterministic deviations
Autorzy:
Poniatowska, M.
Werner, A.
Powiązania:
https://bibliotekanauki.pl/articles/221700.pdf
Data publikacji:
2012
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
coordinate measurement
geometric deviation
free-form surface
regression analysis
CAD model
Opis:
Geometric deviations of free-form surfaces are attributed to many phenomena that occur during machining, both systematic (deterministic) and random in character. Measurements of free-form surfaces are performed with the use of numerically controlled CMMs on the basis of a CAD model, which results in obtaining coordinates of discrete measurement points. The spatial coordinates assigned at each measurement point include both a deterministic component and a random component at different proportions. The deterministic component of deviations is in fact the systematic component of processing errors, which is repetitive in nature. A CAD representation of deterministic geometric deviations might constitute the basis for completing a number of tasks connected with measurement and processing of free-form surfaces. The paper presents the results of testing a methodology of determining CAD models by estimating deterministic geometric deviations. The research was performed on simulated deviations superimposed on the CAD model of a nominal surface. Regression analysis, an iterative procedure, spatial statistics methods, and NURBS modelling were used for establishing the model.
Źródło:
Metrology and Measurement Systems; 2012, 19, 1; 151-158
0860-8229
Pojawia się w:
Metrology and Measurement Systems
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
O analizie portfelowej wartość średnia – wartość zagrożona
On mean - Value at Risk portfolio analysis
Autorzy:
Śleszyńska-Połomska, Anna
Powiązania:
https://bibliotekanauki.pl/articles/422965.pdf
Data publikacji:
2012
Wydawca:
Główny Urząd Statystyczny
Tematy:
wartość zagrożona
analiza portfelowa
model E-VaR bez walorów bezryzykownych
model E-VaR z walorem bezryzykownym
Value at Risk
portfolio analysis
E-VaR model with no risk-free assets
E-VaR model with risk-free asset
Opis:
Praca dotyczy analizy portfelowej, w której ryzyko jest mierzone wartością zagrożoną (VaR), a wektor stóp zwrotu walorów ryzykownych ma rozkład normalny. Przy założeniu, że krótka sprzedaż walorów ryzykownych jest dopuszczalna zbadano przypadki, gdy nie ma waloru pozbawionego ryzyka i gdy taki walor istnieje. Przeanalizowano model Blacka i zmodyfikowany model Tobina, stosując VaR jako miarę ryzyka. Omówiono podobieństwa i różnice między modelami stosującymi odchylenie standardowe jako miarę ryzyka, a tymi stosującymi VaR. Zwrócono uwagę na fakt, że od poziomu ufności przyjmowanego do wyznaczania VaR zależy istnienie portfeli efektywnych. Wyniki uzyskane dla modelu z walorem bezryzykownym i miarą ryzyka VaR nie występują w literaturze.
The article concerns portfolio analysis where risk is measured by value at risk (VaR) assuming that the returns are normally distributed and short-selling of risky securities has no limitations. Two models have been analysed: one with the assumption that no risk-free security exists in the economy, another assuming just one risk-free security. An analysis of Black Model and Modified Tobin Model has been carried out using VaR as the measure of risk. Models with VaR as a measure of risk and standard deviation as measure of risk have been compared. It is shown that, depending on the confidence level used to calculate VaR, an efficient portfolio might not exist. The results for the model with one risk-free asset and VaR as a measure of risk have not been published before and are the original contribution of this paper.
Źródło:
Przegląd Statystyczny; 2012, 59, 4; 386-408
0033-2372
Pojawia się w:
Przegląd Statystyczny
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Timoshenko beam model for vibration analysis of composite steel-polymer concrete box beams
Autorzy:
Niesterowicz, Beata
Dunaj, Paweł
Berczyński, Stefan
Powiązania:
https://bibliotekanauki.pl/articles/2055041.pdf
Data publikacji:
2020
Wydawca:
Polskie Towarzystwo Mechaniki Teoretycznej i Stosowanej
Tematy:
Timoshenko beam
Euler-Bernoulli beam
free vibration
composite beam
finite element model
Opis:
The free vibration model of a steel-polymer concrete beam based on Timoshenko beam theory is presented in this paper. The results obtained on the basis of the model analysis, describing the values of the natural frequencies of the beam vibrations, were compared with the results obtained by the solution of the model formulated on the basis of the classical Euler-Bernoulli beam theory, the finite element model and the results of experimental studies. The developed model is characterized by high compliance with experimental data: the relative error in the case of natural vibration frequencies does not exceed 0.4%, on average 0.2%.
Źródło:
Journal of Theoretical and Applied Mechanics; 2020, 58, 3; 799--810
1429-2955
Pojawia się w:
Journal of Theoretical and Applied Mechanics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Educational customs duties as a crucial element to create free trade
Cło wychowacze jako istotny element tworzenia wolnej wymiany handlowej
Autorzy:
Myszczyszyn, J.
Powiązania:
https://bibliotekanauki.pl/articles/38240.pdf
Data publikacji:
2015
Wydawca:
Szkoła Główna Gospodarstwa Wiejskiego w Warszawie. Wydawnictwo Szkoły Głównej Gospodarstwa Wiejskiego w Warszawie
Tematy:
custom duty
free trade
trade
educational custom duty
economic model
statistical data analysis
Źródło:
Acta Scientiarum Polonorum. Oeconomia; 2015, 14, 4
1644-0757
Pojawia się w:
Acta Scientiarum Polonorum. Oeconomia
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The analysis of non-linear free vibration of FGM nano-beams based on the conformable fractional non-local model
Autorzy:
Rahimi, Z.
Sumelka, W.
Shafiei, S.
Powiązania:
https://bibliotekanauki.pl/articles/201202.pdf
Data publikacji:
2018
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
FGM nano beam
nonlinear free vibration
fractional calculus
integer stress
non-integer stress
gradient’s order
fractional non-local model
rachunek różniczkowy
FGM
drgania swobodne
Opis:
Continuum models generalized by fractional calculus are used in different mechanical problems. In this paper, by using the conformable fractional derivative (CFD) definition, a general form of Eringen non-local theory as a fractional non-local model (FNM) is formulated. It is then used to study the non-linear free vibration of a functional graded material (FGM) nano-beam in the presence of von-Kármán non-linearity. A numerical solution is obtained via Galerkin and multiple scale methods and effects of the integer and non-integer (fractional) order of stress gradient (in the non-local stress-strain relation) on the ratio of the non-local non-linear natural frequency to classical non-linear natural frequency of simply-supported (S-S) and clamped-free (C-F) FGM nano-beams are presented.
Źródło:
Bulletin of the Polish Academy of Sciences. Technical Sciences; 2018, 66, 5; 737-745
0239-7528
Pojawia się w:
Bulletin of the Polish Academy of Sciences. Technical Sciences
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Nonlinear Free Vibration Analysis of Micro-beams Resting on Viscoelastic Foundation Based on the Modified Couple Stress Theory
Autorzy:
Jam, J. E.
Noorabadi, M.
Namdaran, N.
Powiązania:
https://bibliotekanauki.pl/articles/139530.pdf
Data publikacji:
2017
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
nonlinear free vibration
size dependence
modified couple stress theory
Euler-Bernoulli beam model
Galerkin method
swobodne drgania nieliniowe
zależność od wielkości
zmodyfikowana teoria naprężeń momentowych
model belki Eulera-Bernouliego
metoda Galerkina
Opis:
In this paper, nonlinear free vibration analysis of micro-beams resting on the viscoelastic foundation is investigated by the use of the modified couple stress theory, which is able to capture the size effects for structures in micron and sub-micron scales. To this aim, the governing equation of motion and the boundary conditions are derived using the Euler–Bernoulli beam and the Hamilton’s principle. The Galerkin method is employed to solve the governing nonlinear differential equation and obtain the frequency-amplitude algebraic equation. Finally, the effects of different parameters, such as the mode number, aspect ratio of length to height, the normalized length scale parameter and foundation parameters on the natural frequency-amplitude curves of doubly simply supported beams are studied.
Źródło:
Archive of Mechanical Engineering; 2017, LXIV, 2; 239-256
0004-0738
Pojawia się w:
Archive of Mechanical Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Free vibration behaviour of thin-walled concrete box-girder bridge using Perspex sheet experimental model
Autorzy:
Verma, V.
Nallasivam, K.
Powiązania:
https://bibliotekanauki.pl/articles/1818786.pdf
Data publikacji:
2021
Wydawca:
Stowarzyszenie Komputerowej Nauki o Materiałach i Inżynierii Powierzchni w Gliwicach
Tematy:
concrete box-girder bridge
perspex sheet model
modal analysis
finite element method
Matlab
most betonowy
most dźwigarowy
analiza modalna
metoda elementów skończonych
Opis:
Purpose: Curved box-girder bridges offers an excellent solution to the problems associated with traffic congestion. However, owing to their complex geometry, they are subjected to shear lag, torsional warping and cross-sectional distortion, which must be assessed in their study and design. Furthermore, the dynamic behaviour of curved bridges adds to the complexity of the issue, emphasizing the importance of studying free vibration. The purpose of this study is to numerically model the concrete curved box-girder bridge considering torsional warping, distortion and distortional warping effects and to identify key parameters that influence the free vibration response of the box-girder bridge by validating it with experimental and analytical studies. Design/methodology/approach: The concrete bridge is numerically modelled by means of computationally effective thin-walled box-beam finite elements that consider torsional warping, distortion and distortional warping, which are prominent features of thinwalled box-girders. The free vibration analysis of the concrete curved box-girder bridge is performed by developing a finite element based MATLAB program. Findings: The identification of critical parameters that influence the free vibration behaviour of curved thin-walled concrete box-girder bridges is one of the main findings of the study. Each parameter and its effect has been extensively discussed. Research limitations/implications: The study limits for the preliminary design phase of thin-walled box-girder bridge decks, where a complete three-dimensional finite element analysis is unnecessary. The current approach can be extended to future research using a different method, such as finite element grilling technique on multi-span curved bridges having unequal span. Originality/value: The current research implements a finite element formulation in combination with thin-walled beam theory, where an extensive parametric study is conducted on the free vibration behaviour of a concrete thin-walled box-girder bridge, while also accounting for their complex structural actions. The validity of the given numerical formulation is demonstrated by a comparison of the natural frequencies found experimentally. The study carried out will be of great importance for engineers to help them anticipate the modal characteristics of a curved concrete thin-walled girder bridge, which will further be useful for evaluating their dynamic response analysis.
Źródło:
Journal of Achievements in Materials and Manufacturing Engineering; 2021, 106, 2; 56--76
1734-8412
Pojawia się w:
Journal of Achievements in Materials and Manufacturing Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł

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