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Wyszukujesz frazę "gradient" wg kryterium: Temat


Wyświetlanie 1-9 z 9
Tytuł:
Iteratively reweighted least squares classifier and its l2- and l1-regularized Kernel versions
Autorzy:
Łęski, J.
Powiązania:
https://bibliotekanauki.pl/articles/199904.pdf
Data publikacji:
2010
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
classifier design
IRLS
conjugate gradient optimization
gradient projection
Kernel matrix
Opis:
This paper introduces a new classifier design method based on regularized iteratively reweighted least squares criterion function. The proposed method uses various approximations of misclassification error, including: linear, sigmoidal, Huber and logarithmic. Using the represented theorem a kernel version of classifier design method is introduced. The conjugate gradient algorithm is used to minimize the proposed criterion function. Furthermore, .1-regularized kernel version of the classifier is introduced. In this case, the gradient projection is used to optimize the criterion function. Finally, an extensive experimental analysis on 14 benchmark datasets is given to demonstrate the validity of the introduced methods.
Źródło:
Bulletin of the Polish Academy of Sciences. Technical Sciences; 2010, 58, 1; 171-182
0239-7528
Pojawia się w:
Bulletin of the Polish Academy of Sciences. Technical Sciences
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Generalized ordered linear regression with regularization
Autorzy:
Łęski, J.
Henzel, N.
Powiązania:
https://bibliotekanauki.pl/articles/201591.pdf
Data publikacji:
2012
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
linear regression
IRLS
OWA
conjugate gradient optimization
robust methods
Opis:
Linear regression analysis has become a fundamental tool in experimental sciences. We propose a new method for parameter estimation in linear models. The 'Generalized Ordered Linear Regression with Regularization' (GOLRR) uses various loss functions (including the o-insensitive ones), ordered weighted averaging of the residuals, and regularization. The algorithm consists in solving a sequence of weighted quadratic minimization problems where the weights used for the next iteration depend not only on the values but also on the order of the model residuals obtained for the current iteration. Such regression problem may be transformed into the iterative reweighted least squares scenario. The conjugate gradient algorithm is used to minimize the proposed criterion function. Finally, numerical examples are given to demonstrate the validity of the method proposed.
Źródło:
Bulletin of the Polish Academy of Sciences. Technical Sciences; 2012, 60, 3; 481-489
0239-7528
Pojawia się w:
Bulletin of the Polish Academy of Sciences. Technical Sciences
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Resonant DC link inverters for AC motor drive systems – critical evaluation
Autorzy:
Turzyński, Marek
Chrzan, P. J.
Powiązania:
https://bibliotekanauki.pl/articles/200688.pdf
Data publikacji:
2019
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
soft-switching
resonant DC link inverter
quasiresonant DC link inverter
common-mode voltage
voltage gradient
zero voltage switching
przekształtnik quasirezonansowy DC
gradient napięcia
przekształtnik rezonansowy DC/DC
Opis:
In this survey paper, resonant and quasiresonant DC link inverters are reexamined for AC motor drive applications. Critical evaluation of representative topologies is based on simulation and waveform analysis to characterize current/voltage stress of components, control timing constraints and feasibility. A special concern over inverter common-mode voltage and voltage gradient du/dt limitation capacity is discussed for motor bearing and winding insulation safety. Experimental records of the laboratory developed parallel quasiresonant DC link inverter feeding induction motor confirm results of analysis. Comparative tables and simulation results demonstrate characteristic features of various schemes.
Źródło:
Bulletin of the Polish Academy of Sciences. Technical Sciences; 2019, 67, 2; 241-252
0239-7528
Pojawia się w:
Bulletin of the Polish Academy of Sciences. Technical Sciences
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Incompressible limit for a magnetostrictive energy functional
Autorzy:
Gambin, B.
Bielski, W.
Powiązania:
https://bibliotekanauki.pl/articles/201841.pdf
Data publikacji:
2013
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
gamma-convergence
incompressibility
magnetostrictive material
second gradient of deformation
existence of minimizers
Opis:
The modern materials undergoing large elastic deformations and exhibiting strong magnetostrictive effect are modelled here by free energy functionals for nonlinear and non-local magnetoelastic behaviour. The aim of this work is to prove a new theorem which claims that a sequence of free energy functionals of slightly compressible magnetostrictive materials with a non-local elastic behaviour, converges to an energy functional of a nearly incompressible magnetostrictive material. This convergence is referred to as a Γ -convergence. The non-locality is limited to non-local elastic behaviour which is modelled by a term containing the second gradient of deformation in the energy functional.
Źródło:
Bulletin of the Polish Academy of Sciences. Technical Sciences; 2013, 61, 4; 1025-1030
0239-7528
Pojawia się w:
Bulletin of the Polish Academy of Sciences. Technical Sciences
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Analysis of multi-step algorithms for cognitive maps learning
Autorzy:
Jastriebow, A.
Poczęta, K.
Powiązania:
https://bibliotekanauki.pl/articles/201551.pdf
Data publikacji:
2014
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
cognitive maps
multistep learning algorithm
gradient method
Hebbian algorithm
mapy poznawcze
wieloetapowe nauki algorytmu
metoda gradientu
algorytm kWTA
Opis:
This article is devoted to the analysis of multi-step algorithms for cognitive maps learning. Cognitive maps and multi-step supervised learning based on a gradient method and unsupervised one based on the non-linear Hebbian algorithm were described. Comparative analysis of these methods to one-step algorithms, from the point of view of the speed of convergence of a learning algorithm and the influence on the work of the decision systems was performed. Simulation results were done on prepared software tool ISEMK. Obtained results show that implementation of the multi-step technique gives certain possibilities to get quicker values of target relations values and improve the operation of the learned system.
Źródło:
Bulletin of the Polish Academy of Sciences. Technical Sciences; 2014, 62, 4; 735-741
0239-7528
Pojawia się w:
Bulletin of the Polish Academy of Sciences. Technical Sciences
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Determination of synchronous generator nonlinear model parameters based on power rejection tests using a gradient optimization algorithm
Autorzy:
Boboń, A.
Nocoń, A.
Paszek, S.
Pruski, P.
Powiązania:
https://bibliotekanauki.pl/articles/200774.pdf
Data publikacji:
2017
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
gradient optimization algorithms
synchronous generator model
parameter estimation
load rejection test
algorytm optymalizacji gradientu
modele generatorów synchronicznych
estymacja parametrów
test odrzucenia ładunku
Opis:
The paper presents a method for determining electromagnetic parameters of different synchronous generator models based on dynamic waveforms measured at power rejection. Such a test can be performed safely under normal operating conditions of a generator working in a power plant. A generator model was investigated, expressed by reactances and time constants of steady, transient, and subtransient state in the d and q axes, as well as the circuit models (type (3,3) and (2,2)) expressed by resistances and inductances of stator, excitation, and equivalent rotor damping circuits windings. All these models approximately take into account the influence of magnetic core saturation. The least squares method was used for parameter estimation. There was minimized the objective function defined as the mean square error between the measured waveforms and the waveforms calculated based on the mathematical models. A method of determining the initial values of those state variables which also depend on the searched parameters is presented. To minimize the objective function, a gradient optimization algorithm finding local minima for a selected starting point was used. To get closer to the global minimum, calculations were repeated many times, taking into account the inequality constraints for the searched parameters. The paper presents the parameter estimation results and a comparison of the waveforms measured and calculated based on the final parameters for 200 MW and 50 MW turbogenerators.
Źródło:
Bulletin of the Polish Academy of Sciences. Technical Sciences; 2017, 65, 4; 479-488
0239-7528
Pojawia się w:
Bulletin of the Polish Academy of Sciences. Technical Sciences
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Producibility of the ion-exchange method in manufacturing gradient refractive index in glass
Autorzy:
Rogoziński, R.
Powiązania:
https://bibliotekanauki.pl/articles/201262.pdf
Data publikacji:
2014
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
ion exchange in glass
diffusion equation
planar gradient waveguides
effective indicies
wymiana jonowa w szkle
równanie dyfuzji
płaskie falowody gradientu
skuteczne indeksy
Opis:
This paper presents the technological aspect of application of the ion exchange method in producing gradient refractive index in glass. The possibility of predictable and repeatable producing of the changes in glass refraction with the use of this method has been presented, as well as the method of in situ control of the process of diffusion doping of glass based on the measurement of the temperature. This method is based on simultaneous (to the carried process) solving the nonlinear diffusion equation modeling the spatio-temporal changes in normalized concentration of the admixture ions in glass. For this purpose the knowledge of temperature characteristics of diffusion coefficients of exchanged ions is used. The result of such control of diffusion processes is information on the current (temporary) refractive index profile of the resulting waveguide. The presented method of control has been confirmed by experimental results, which concern modeling and measurements of planar waveguide structures of slab type. The proposed methodology can also be used to control the diffusion processes of producing another type of two- and three-dimensional gradient structures. According to the author’s knowledge the method mentioned above has not been described in literature before.
Źródło:
Bulletin of the Polish Academy of Sciences. Technical Sciences; 2014, 62, 4; 655-665
0239-7528
Pojawia się w:
Bulletin of the Polish Academy of Sciences. Technical Sciences
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:
On fractional vectorial calculus
Autorzy:
Ortigueira, M. D.
Machado, J. T. M.
Powiązania:
https://bibliotekanauki.pl/articles/201507.pdf
Data publikacji:
2018
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
Grunwald-Letnikov
Liouville
fractional gradient
fractional divergence
fractional curl
fractional Laplacian
Green’s theorem
Stokes’ theorem
Ostrogradski-Gauss’s theorem
tensor Greena
równanie Stokesa
równanie Gaussa
równanie Laplace'a
Opis:
This paper reviews the fractional vectorial differential operators proposed previously and introduces the fractional versions of the classic Green’s, Stokes’, and Ostrogradski-Gauss’s integral theorems. The suitability of fractional derivatives for sciences and the Laplacian definition are also discussed.
Źródło:
Bulletin of the Polish Academy of Sciences. Technical Sciences; 2018, 66, 4; 389-402
0239-7528
Pojawia się w:
Bulletin of the Polish Academy of Sciences. Technical Sciences
Dostawca treści:
Biblioteka Nauki
Artykuł
    Wyświetlanie 1-9 z 9

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