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Wyświetlanie 1-15 z 446
Tytuł:
On the numerical approximation of first-order Hamilton-Jacobi equations
Autorzy:
Abgrall, R.
Perrier, V.
Powiązania:
https://bibliotekanauki.pl/articles/929712.pdf
Data publikacji:
2007
Wydawca:
Uniwersytet Zielonogórski. Oficyna Wydawnicza
Tematy:
równanie Hamiltona-Jacobiego
aproksymacja
zagadnienie Cauchy'ego-Dirichleta
siatka trójkątna
approximation of Hamilton-Jacobi equations
viscous solution
Cauchy-Dirichlet problem
triangular mesh
Opis:
Some methods for the numerical approximation of time-dependent and steady first-order Hamilton-Jacobi equations are reviewed. Most of the discussion focuses on conformal triangular-type meshes, but we show how to extend this to the most general meshes. We review some first-order monotone schemes and also high-order ones specially dedicated to steady problems.
Źródło:
International Journal of Applied Mathematics and Computer Science; 2007, 17, 3; 403-412
1641-876X
2083-8492
Pojawia się w:
International Journal of Applied Mathematics and Computer Science
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Estimating the Approximation Uncertainty for Digital Materials Subjected to Stress Relaxation Tests
Autorzy:
Adamczak, S.
Bochnia, J.
Powiązania:
https://bibliotekanauki.pl/articles/220966.pdf
Data publikacji:
2016
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
digital materials
stress relaxation
approximation uncertainty
Opis:
The main aim of the study was to determine the goodness of fit between the relaxation function described with a rheological model and the real (experimental) relaxation curves obtained for digital materials fabricated with a Connex 350 printer using the PolyJet additive manufacturing technology. The study involved estimating the uncertainty of approximation of the parameters of the theoretical relaxation curve. The knowledge of digital materials is not yet sufficient; their properties are not so well-known as those of metallic alloys or plastics used as structural materials. Intensive research is thus required to find out more about their behavior in various conditions. From the calculation results, i.e. the uncertainty of approximation of the relaxation function parameters, it is evident that the experimental curves coincide with the curves obtained by means of the solid model when the approximation uncertainty is taken into account. This suggests that the assumed solid model is well-suited to describe a real material.
Źródło:
Metrology and Measurement Systems; 2016, 23, 4; 545-553
0860-8229
Pojawia się w:
Metrology and Measurement Systems
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Beta Fuzzy Logic Systems: Approximation Properties in the mimo Case
Autorzy:
Alimi, A. M.
Hassine, R.
Selmi, M.
Powiązania:
https://bibliotekanauki.pl/articles/908193.pdf
Data publikacji:
2003
Wydawca:
Uniwersytet Zielonogórski. Oficyna Wydawnicza
Tematy:
informatyka
beta function
universal approximation property
best approximation property
interpolation property
Sugeno fuzzy model
MIMO systems
Opis:
Many researches have been interested in the approximation properties of Fuzzy Logic Systems (FLS), which, like neural networks, can be seen as approximation schemes. Almost all of them tackled the Mamdani fuzzy model, which was shown to have many interesting approximation features. However, only in few cases the Sugeno fuzzy model was considered. In this paper, we are interested in the zero-order Multi-Input-Multi-Output (MIMO) Sugeno fuzzy model with Beta membership functions. This leads to Beta Fuzzy Logic Systems (BFLS). We show that BFLSs are universal approximators. We also prove that they possess the best approximation property and the interpolation characteristic.
Źródło:
International Journal of Applied Mathematics and Computer Science; 2003, 13, 2; 225-238
1641-876X
2083-8492
Pojawia się w:
International Journal of Applied Mathematics and Computer Science
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Beta Fuzzy Logic Systems: Approximation Properties in the Siso Case
Autorzy:
Alimi, A. M.
Hassine, R.
Selmi, M.
Powiązania:
https://bibliotekanauki.pl/articles/911157.pdf
Data publikacji:
2000
Wydawca:
Uniwersytet Zielonogórski. Oficyna Wydawnicza
Tematy:
funkcja beta
własność aproksymacyjna
model rozmyty
beta function
universal approximation property
best approximation property
interpolation property
Sugeno fuzzy model
SISO systems
Opis:
In this paper, a Single-Input Single-Output (SISO) Sugeno fuzzy model of the zeroth order with Beta membership functions for input variables is adopted. After the introduction of Beta Fuzzy Logic Systems (BFLS) a constructive theory is developed to establish the fact that they are universal approximators. Based on this theory, an algorithm, which can actually construct a BFLS approximating a given continuous function with an arbitrary degree of accuracy, is described. We then show that BFLSs satisfy more critical properties which are the best approximation property and the interpolation property. We complete the paper with a series of numerical comparisons between the approximation performances of BFLSs and other classes of widely used fuzzy logic systems. These comparisons confirm that BFLSs perform best in all the cases studied.
Źródło:
International Journal of Applied Mathematics and Computer Science; 2000, 10, 4; 857-875
1641-876X
2083-8492
Pojawia się w:
International Journal of Applied Mathematics and Computer Science
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Beta neuro-fuzzy systems
Autorzy:
Alimi, A. M.
Powiązania:
https://bibliotekanauki.pl/articles/1931568.pdf
Data publikacji:
2003
Wydawca:
Politechnika Gdańska
Tematy:
beta function
kernel based neural networks
Sugeno fuzzy model
neuro-fuzzy systems
universal approximation property
learning algorithms
incremental learning
Opis:
In this paper we present the Beta function and its main properties. A key feature of the Beta function, which is given by the central-limit theorem, is also given. We then introduce a new category of neural networks based on a new kernel: the Beta function. Next, we investigate the use of Beta fuzzy basis functions for the design of fuzzy logic systems. The functional equivalence between Beta-based function neural networks and Beta fuzzy logic systems is then shown with the introduction of Beta neuro-fuzzy systems. By using the SW theorem and expanding the output of the Beta neuro-fuzzy system into a series of Beta fuzzy-based functions, we prove that one can uniformly approximate any real continuous function on a compact set to any arbitrary accuracy. Finally, a learning algorithm of the Beta neuro-fuzzy system is described and illustrated with numerical examples.
Źródło:
TASK Quarterly. Scientific Bulletin of Academic Computer Centre in Gdansk; 2003, 7, 1; 23-41
1428-6394
Pojawia się w:
TASK Quarterly. Scientific Bulletin of Academic Computer Centre in Gdansk
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
New characterizations of reproducing kernel Hilbert spaces and applications to metric geometry
Autorzy:
Alpay, Daniel
Jorgensen, Palle E.T.
Powiązania:
https://bibliotekanauki.pl/articles/2051893.pdf
Data publikacji:
2021
Wydawca:
Akademia Górniczo-Hutnicza im. Stanisława Staszica w Krakowie. Wydawnictwo AGH
Tematy:
reproducing kernel
positive definite functions
approximation
algorithms
measures
stochastic processes
Opis:
We give two new global and algorithmic constructions of the reproducing kernel Hilbert space associated to a positive definite kernel. We further present a general positive definite kernel setting using bilinear forms, and we provide new examples. Our results cover the case of measurable positive definite kernels, and we give applications to both stochastic analysis and metric geometry and provide a number of examples.
Źródło:
Opuscula Mathematica; 2021, 41, 3; 283-300
1232-9274
2300-6919
Pojawia się w:
Opuscula Mathematica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Analysis of glued functions approximating real indicator diagram of engine running on different fuels
Ocena funkcji sklejanych aproksymujących rzeczywisty wykres indykatorowy silnika o zapłonie samoczynnym, zasilanego różnymi paliwami
Autorzy:
Ambrozik, A.
Ambrozik, T.
Łagowski, P.
Powiązania:
https://bibliotekanauki.pl/articles/248127.pdf
Data publikacji:
2008
Wydawca:
Instytut Techniczny Wojsk Lotniczych
Tematy:
transport
diagnostyka
silniki spalinowe
wykres indykatorowy
aproksymacja
diagnostics
combustion engines
indicator diagram
approximation
Opis:
The paper presents methodology for the approximation of real indicator diagrams, averaged over 50 runs, with the use of glued functions, which analytically describe the form of those diagrams. Coefficients of approximating functions can apply to the diagnostics and control of the combustion process in piston combustion engine. The paper aims to provide an analysis and comparative assessment of the influence of different fuels fuelled AD3.152 UR engine operation conditions (external speed characteristics and load characteristics) on the values of the above-mentioned coefficients of glued functions. The approximation of indicator diagrams accounts for the smoothing of the indicator diagram in the period between inlet valve closure and outlet valve opening, i.e. when the engine working cycle is done in the closed thermodynamic system. Experimental investigations and analysis of results were carried out for the engine operating in the mode of external speed characteristics for ne<1000-2000 rpm> and in the mode of load characteristics at the crankshaft rotational velocity corresponding to the maximum torque of the engine.
W artykule przedstawiono metodykę aproksymacji uśrednionych według 50-ciu realizacji rzeczywistych wykresów indykatorowych za pomocą funkcji sklejanych, analitycznie opisujących postać tych wykresów. Współczynniki funkcji aproksymujących mogą by wykorzystane do diagnostyki i sterowania przebiegiem procesu spalania w tłokowym silniku spalinowym. Celem artykułu jest analiza i ocena porównawcza wpływu warunków pracy silnika AD3.152 UR (zewnętrzna charakterystyka prędkościowa i charakterystyka obciążeniowa), zasilanego różnymi paliwami na wartości w/w współczynników funkcji sklejanych. Zastosowana aproksymacja wykresów indykatorowych zapewnia wygładzenie wykresu indykatorowego w okresie od zamknięcia zaworu dolotowego do otwarcia zaworu wylotowego tzn. w okresie realizacji cyklu pracy silnika w zamkniętym układzie termodynamicznym. Badania eksperymentalne i analizę otrzymanych wyników przeprowadzono dla pracy silnika według zewnętrznej charakterystyki prędkościowej dla ne less than 1000-2000 obr/min i charakterystyki obciążeniowej sporządzonej przy prędkości obrotowej wału korbowego, odpowiadającej maksymalnemu momentowi obrotowemu silnika.
Źródło:
Journal of KONES; 2008, 15, 3; 9-18
1231-4005
2354-0133
Pojawia się w:
Journal of KONES
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Continuous and smooth minimax spline-approximation of sensor temperature characteristic and its sensitivity
Ciągła i gładka aproksymacja minimaksowa funkcjami sklejanymi charakterystyki czujnika temperatury
Autorzy:
Andrunyk, V.
Malachivskyy, P.
Pizyur, Y.
Yatsuk, V.
Powiązania:
https://bibliotekanauki.pl/articles/155206.pdf
Data publikacji:
2007
Wydawca:
Stowarzyszenie Inżynierów i Techników Mechaników Polskich
Tematy:
spline approximation
minimax Chebyshev polynom
aproksymacja funkcjami sklejanymi
Opis:
The problem under consideration is the construction of continuous and smooth spline-approximation whose any link is polynomial approximation according to a minimax criterion. The algorithm of such a spline-approximation with a priory given error is proposed. The practical sample of its application for the description of a temperature characteristic and sensitivity of cryogen thermodiode sensor is described.
Zbadano własności ciągłej i zarazem gładkiej aproksymacji funkcjami sklejanymi, w których wszystkie ogniwa są wielomianami. Zaproponowano algorytm konstrukcji takiego przybliżenia realizującego aproksymację z założoną dokładnością. Algorytm ten zastosowano do przybliżenia charakterystyki temperaturowej czujnika diodowego pracującego w obszarze temperatur kriogenicznych.
Źródło:
Pomiary Automatyka Kontrola; 2007, R. 53, nr 9 bis, 9 bis; 617-620
0032-4140
Pojawia się w:
Pomiary Automatyka Kontrola
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Bidirectionally stretched flow of Jeffrey liquid with nanoparticles, Rosseland radiation and variable thermal conductivity
Autorzy:
Archana, M.
Gireesha, B. J.
Rashidi, M. M.
Prasannakumara, B. C.
Gorla, R. S. R.
Powiązania:
https://bibliotekanauki.pl/articles/240409.pdf
Data publikacji:
2018
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
heat mass transfer
jeffrey nanofluid
variable thermal conductivity
rosseland approximation
suction
ciepło
masa
zmienna przewodność cieplna
aproksymacja
ssanie
Opis:
Heat and mass transfer stretched flow of an incompressible, electrically conducting Jeffrey fluid has been studied numerically. Nanoparticles are suspended in the base fluid and it has many applications such as cooling of engines, thermal absorption systems, lubricants fuel cell, nanodrug delivery system and so on. Temperature dependent variable thermal conductivity with Rosseland approximation is taken into account and suction effect is employed in the boundary conditions. The governing partial differential equations are first transformed into set of ordinary differential equations using selected similarity transformations, which are then solved numerically using Runge-Kutta-Felhberg fourth-fifth order method along with shooting technique. The flow, heat and mass transfer characteristics with local Nusselt number for various physical parameters are presented graphically and a detailed discussion regarding the effect of flow parameters on velocity and temperature profiles are provided. It is found that, increase of variable thermal conductivity, radiation, Brownian motion and thermophoresis parameter increases the rate of heat transfer. Local Nusselt number has been computed for various parameters and it is observed that, in the presence of variable thermal conductivity and Rosseland approximation, heat transfer characteristics are higher as compared to the constant thermal conductivity and linear thermal radiation.
Źródło:
Archives of Thermodynamics; 2018, 39, 4; 33--57
1231-0956
2083-6023
Pojawia się w:
Archives of Thermodynamics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Fuzzy goal programming technique for multi-objective indefinite quadratic bilevel programming problem
Autorzy:
Arora, R.
Gupta, K.
Powiązania:
https://bibliotekanauki.pl/articles/1403683.pdf
Data publikacji:
2020
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
bilevel programming
indefinite quadratic programming
multi-objective programming
pay-off matrix
Taylor series approximation
LINGO 17.0
Opis:
Bilevel programming problem is a non-convex two stage decision making process in which the constraint region of upper level is determined by the lower level problem. In this paper, a multi-objective indefinite quadratic bilevel programming problem (MOIQBP) is presented. The defined problem (MOIQBP) has multi-objective functions at both the levels. The followers are independent at the lower level. A fuzzy goal programming methodology is employed which minimizes the sum of the negative deviational variables of both the levels to obtain highest membership value of each of the fuzzy goal. The membership function for the objective functions at each level is defined. As these membership functions are quadratic they are linearized by Taylor series approximation. The membership function for the decision variables at both levels is also determined. The individual optimal solution of objective functions at each level is used for formulating an integrated pay-off matrix. The aspiration levels for the decision makers are ascertained from this matrix. An algorithm is developed to obtain a compromise optimal solution for (MOIQBP). A numerical example is exhibited to evince the algorithm. The computing software LINGO 17.0 has been used for solving this problem.
Źródło:
Archives of Control Sciences; 2020, 30, 4; 683-699
1230-2384
Pojawia się w:
Archives of Control Sciences
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Mathematical Modeling and Numerical Analysis of Nonstationary Plane-Parallel Flows of Viscous Incompressible Fluid by R-Functions and Galerkin Method
Autorzy:
Artyukh, A.
Sidorov, M.
Powiązania:
https://bibliotekanauki.pl/articles/411247.pdf
Data publikacji:
2014
Wydawca:
Polska Akademia Nauk. Oddział w Lublinie PAN
Tematy:
nonstationary flow
incompressible fluid
stream function
method of successive approximation
R-functions method
Galerkin method
Opis:
This paper is dedicated to nonstationary plane-parallel flows of viscous incompressible fluid in finite simply connected domains. Theorem of the solution uniqueness is presented. The method of successive approximation, the Galerkin method and the R-functions method are used to obtain the numerical solution, which was tested on the problem with known solution.
Źródło:
ECONTECHMOD : An International Quarterly Journal on Economics of Technology and Modelling Processes; 2014, 3, 3; 3-11
2084-5715
Pojawia się w:
ECONTECHMOD : An International Quarterly Journal on Economics of Technology and Modelling Processes
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Degenerate evolution problems and Beta-type operators
Autorzy:
Attalienti, Antonio
Campiti, Michele
Powiązania:
https://bibliotekanauki.pl/articles/1206074.pdf
Data publikacji:
2000
Wydawca:
Polska Akademia Nauk. Instytut Matematyczny PAN
Tematy:
approximation process
$C_0$-semigroups of contractions
Beta-type operators
differential operators
Opis:
The present paper is concerned with the study of the differential operator Au(x):=α(x)u''(x)+β(x)u'(x) in the space C([0,1)] and of its adjoint Bv(x):=((αv)'(x)-β(x)v(x))' in the space $L^1(0,1)$, where α(x):=x(1-x)/2 (0≤x≤1). A careful analysis of their main properties is carried out in view of some generation results available in [6, 12, 20] and [25]. In addition, we introduce and study two different kinds of Beta-type operators as a generalization of similar operators defined in [18]. Among the corresponding approximation results, we show how they can be used in order to represent explicitly the solutions of the Cauchy problems associated with the operators A and Ã, where à is equal to B up to a suitable bounded additive perturbation.
Źródło:
Studia Mathematica; 2000, 140, 2; 117-139
0039-3223
Pojawia się w:
Studia Mathematica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Solutions to p(x)-Laplace type equations via nonvariational techniques
Autorzy:
Avci, M.
Powiązania:
https://bibliotekanauki.pl/articles/255416.pdf
Data publikacji:
2018
Wydawca:
Akademia Górniczo-Hutnicza im. Stanisława Staszica w Krakowie. Wydawnictwo AGH
Tematy:
Leray-Lions type operator
nonlinear monotone operator
approximation
variable Lebesgue spaces
Opis:
In this article, we consider a class of nonlinear Dirichlet problems driven by a Leray-Lions type operator with variable exponent. The main result establishes an existence property by means of nonvariational arguments, that is, nonlinear monotone operator theory and approximation method. Under some natural conditions, we show that a weak limit of approximate solutions is a solution of the given quasilinear elliptic partial differential equation involving variable exponent.
Źródło:
Opuscula Mathematica; 2018, 38, 3; 291-305
1232-9274
2300-6919
Pojawia się w:
Opuscula Mathematica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Avoiding look-ahead in the Lanczos method and Padé approximation
Autorzy:
Ayachour, E.
Powiązania:
https://bibliotekanauki.pl/articles/1338862.pdf
Data publikacji:
1999
Wydawca:
Polska Akademia Nauk. Instytut Matematyczny PAN
Tematy:
extrapolation methods
orthogonal and biorthogonal polynomials
Padé approximation
Lanczos method
Opis:
In the non-normal case, it is possible to use various look-ahead strategies for computing the elements of a family of regular orthogonal polynomials. These strategies consist in jumping over non-existing and singular orthogonal polynomials by solving triangular linear systems. We show how to avoid them by using a new method called ALA (Avoiding Look-Ahead), for which we give three principal implementations. The application of ALA to Padé approximation, extrapolation methods and Lanczos method for solving systems of linear equations is discussed.
Źródło:
Applicationes Mathematicae; 1999, 26, 1; 33-62
1233-7234
Pojawia się w:
Applicationes Mathematicae
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Quasilinear vector differential equations with maximal monotone terms and nonlinear boundary conditions
Autorzy:
Bader, Ralf
Papageorgiou, Nikolaos
Powiązania:
https://bibliotekanauki.pl/articles/1208032.pdf
Data publikacji:
2000
Wydawca:
Polska Akademia Nauk. Instytut Matematyczny PAN
Tematy:
Dirichlet
maximal monotone operator
Yosida approximation
monotone operator
resolvent operator
measurable selection
demicontinuous operator
Neumann and periodic problems
coercive operator
projection theorem
Opis:
We consider a quasilinear vector differential equation which involves the p-Laplacian and a maximal monotone map. The boundary conditions are nonlinear and are determined by a generally multivalued, maximal monotone map. We prove two existence theorems. The first assumes that the maximal monotone map involved is everywhere defined and in the second we drop this requirement at the expense of strengthening the growth hypothesis on the vector field. The proofs are based on the theory of operators of monotone type and on the Leray-Schauder fixed point theorem. At the end we present some special cases (including the classical Dirichlet, Neumann and periodic problems), which illustrate the general and unifying features of our work.
Źródło:
Annales Polonici Mathematici; 2000, 73, 1; 69-92
0066-2216
Pojawia się w:
Annales Polonici Mathematici
Dostawca treści:
Biblioteka Nauki
Artykuł
Wyświetlanie 1-15 z 446

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