Wyniki wyszukiwania - BazTech

1

Wskazywanie punktu startowego dla iteracyjnych algorytmów obliczania położenia z użyciem sieci neuronowej

Sadowski Jarosław, Stefański Jacek

Przegląd Telekomunikacyjny + Wiadomości Telekomunikacyjne

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2023

|

nr 4

244--247

PL

W referacie przedstawiono wyniki badań nad możliwością wskazywania punktu startowego do pierwszej iteracji dla algorytmu iteracyjnego obliczania położenia w systemie lokalizacji dwuwymiarowej. Do wskazywania punktu startowego użyto jednokierunkowej sieci neuronowej a celem badań było znalezienie jak najmniejszej struktury sieci, pozwalającej na zbieżność algorytmu estymacji położenia w całym obszarze badań.

EN

The paper presents the results of a study on the possibility of starting point selection for the first iteration for an iterative position calculation algorithm in a two dimensional location system. A feedforward neural network was used to indicate the starting point and the aim of the study was to find the smallest possible network structure, allowing the position estimation algorithm to converge over the entire study area.

2

An iterative algorithm for random upper bound kinematical analysis

Chwała Marcin

Studia Geotechnica et Mechanica

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2022

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Vol. 44, nr 1

13--25

EN

A new approach for stochastic upper bound kinematical analyses is described. The study proposes an iterative algorithm that uses the Vanmarcke spatial averaging and kinematical failure mechanisms. The iterative procedure ensures the consistency between failure geometry and covariance matrix, which influences the quality of the results. The proposed algorithm can be applied to bearing capacity evaluation or slope stability problems. The iterative algorithm is used in the study to analyse the three-dimensional undrained bearing capacity of shallow foundations and the bearing capacity of the foundation for two-layered soil, in both cases, the soil strength spatial variability is included. Moreover, the obtained results are compared with those provided by the algorithm, based on the constant covariance matrix. The study shows that both approaches provide similar results for a variety of foundation shapes and scale of fluctuation values. Therefore, the simplified algorithm can be used for purposes that require high computational efficiency and for practical applications. The achieved efficiency using a constant covariance matrix for one realisation of a three-dimensional bearing capacity problem that includes the soil strength spatial variability results in about 0.5 seconds for a standard notebook. The numerical example presented in the study indicates the importance of the iterative algorithm for further development of the failure mechanism application in probabilistic analyses. Moreover, because the iterative algorithm is based on the upper bound theorem, it could be utilised as a reference for other methods for spatially variable soil.

3

Analiza właściwości iteracyjnego algorytmu najmniejszych kwadratów w pomiarze częstotliwości sieci energetyczne

Krajewski Mariusz, Sienkowski Sergiusz

Przegląd Elektrotechniczny

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2022

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R. 98, nr 11

114--117

PL

W artykule przedstawiono badania symulacyjne i doświadczalne właściwości iteracyjnego algorytmu opartego na metodzie najmniejszych kwadratów, w pomiarze częstotliwości sieci energetycznej. Analizowano możliwość poprawy dokładności algorytmu poprzez zastosowanie filtracji cyfrowej próbek oraz uśrednianie wyników pomiarów. Badania przeprowadzono w warunkach stacjonarnych i dynamicznych. Wyniki badań porównano z wynikami otrzymanymi dla algorytmu opartego na DFT.

EN

The article presents simulation and experimental research of properties of an iterative algorithm based on the least squares method in measuring the frequency of the power grid. The possibility of improving the accuracy of the algorithm by applying digital filtering of samples and averaging the measurement results was analyzed. The research was carried out in stationary conditions and dynamic. The test results were compared with those obtained for the DFT-based algorithm.

4

Numerical simulation for train-track-bridge dynamic interaction considering damage constitutive relation of concrete tracks

Xu Lei, Yu Zhiwu, Shan Zhi

Archives of Civil and Mechanical Engineering

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2021

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Vol. 21, no. 3

533--555

EN

In this work, a novel and practical method is developed to depict the track slab damage and residual strain evolution, where the concrete damage constitutive relation of track slabs is considered within the train–track–bridge dynamics framework. A three-step strain method is presented to judge the load/unloading, compression/tension status of track slab elements ergodically, so that the damage condition and residual strain of track slabs can be determined. To improve the computational accuracy and efficiency, the combination of the matrix augment method and iterative solution algorithm is elucidated in detail. To validate the present model, the solutions among incremental solution, iterative solution, and non-iterative solution are firstly illustrated, and then experimental studies are performed to declare the effectiveness of this model in characterising strain/stress relation of concrete no matter in compression state or in tension state, and finally, other model results are also introduced to prove the effectiveness of this model. In the numerical studies, the damage distributions of track slabs in the longitudinal and lateral direction are presented, where the influence of track irregularities and track slab positions on the bridge is clarified, besides, the evolution of the damage and residual strain of a track slab subject to a moving train is revealed.

5

Approximation solvability for a system of implicit nonlinear variational inclusions with H-monotone operators

Kim J. K., Bhat M. I.

Demonstratio Mathematica

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2018

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Vol. 51, nr 1

241--254

EN

In this paper, we introduce and study a new system of variational inclusions which is called a system of nonlinear implicit variational inclusion problems with A-monotone and H-monotone operators in semi-inner product spaces. We define the resolvent operator associated with A-monotone and H-monotone operators and prove its Lipschitz continuity. Using resolvent operator technique, we prove the existence and uniqueness of solution for this new system of variational inclusions. Moreover, we suggest an iterative algorithm for approximating the solution of this system and discuss the convergence analysis of the sequences generated by the iterative algorithm under some suitable conditions.

6

RERS2014 and MRS2014: new high-precision rigid Earth rotation and Moon rotation series

Pashkevich V. V.

Artificial Satellites : Journal of Planetary Geodesy

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2015

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Vol. 50, No. 1

35--40

EN

Numerical investigation of the Earth and Moon rotational motion dynamics is carried out at a long time intervals. In our previous studies (Pashkevich, 2013), (Pashkevich and Eroshkin, 2011) the high-precision Rigid Earth Rotation Series (designated RERS2013) and Moon Rotation Series (designated MRS2011) were constructed. RERS2013 are dynamically adequate to the JPL DE422/LE422 (Folkner, 2011) ephemeris over 2000 and 6000 years and include about 4113 periodical terms (without attempt to estimate new subdiurnal and diurnal periodical terms). MRS2011 are dynamically adequate to the JPL DE406/LE406 (Standish, 1998) ephemeris over 418, 2000 and 6000 years and include about 1520 periodical terms. In present research have been improved the Rigid Earth Rotation Series RERS2013 and Moon Rotation Series MRS2011, and as a result have been constructed the new high-precision Rigid Earth Rotation Series RERS2014 and Moon Rotation Series MRS2014 dynamically adequate to the JPL DE422/LE422 ephemeris over 2000 and 6000 years, respectively. The elaboration of RERS2013 is carried out by means recalculation of sub-diurnal and diurnal periodical terms. The residuals in Euler angles between the numerical solution and RERS2014 do not surpass 3 μas over 2000 years. Improve the accuracy of the series MRS2011 is obtained by using the JPL DE422/LE422 ephemeris. The residuals in the perturbing terms of the physical librations between the numerical solution and MRS2014 do not surpass 8 arc seconds over 6000 years.

7

RERS2013: a new high-precision rigid Earth rotation series

Pashkevich V. V.

Artificial Satellites : Journal of Planetary Geodesy

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2014

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Vol. 49, No. 3

161--177

EN

In the previous investigation (Pashkevich, 2013) the high-precision Rigid Earth Rotation Series (designated RERS2012) dynamically adequate to the JPL DE406/LE406 (Standish, 1998) ephemeris over 2000 and 6000 years were constructed. The main aim of present research is improvement of the Rigid Earth Rotation Series RERS2012 by using the JPL DE422/LE422 (Folkner, 2011) ephemeris, and as a result is produced construction of the new high-precision Rigid Earth Rotation Series dynamically adequate to the JPL DE422/LE422 ephemeris over 2000 and 6000 years. The discrepancies in Euler angles between the high-precision numerical solutions and the semi-analytical solutions of the rigid Earth rotation problem are investigated by least squares and spectral analysis methods using the iterative algorithm (Pashkevich, 2013). In order to demonstrate the good convergence of this iterative algorithm are constructed additional solutions of the rigid Earth rotation dynamically adequate to the JPL DE422/LE422 over 2000 years by improvement solutions SMART97 (Bretagnon et al., 1998) and S9000 (Pashkevich and Eroshkin, 2005a). As the results of this investigation, the new improved high-precision Rigid Earth Rotation Series RERS2013 dynamically adequate to the DE422/LE422 ephemeris over 2000 and 6000 years have been constructed. The discrepancies in Euler angles between the numerical solution and RERS2013 do not surpass: 4 as over 2000 years, 1 mas over 6000 years. The RERS2013 series is more accurate than the RERS2012 series, which is dynamically adequate to the DE406/LE406 ephemeris. The good convergence of the iterative algorithm of this study has been confirmed.

8

Approximate Discrete Reconstruction Algorithm

Batenburg K. J., Fortes W., Tijdeman R.

Fundamenta Informaticae

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2013

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Vol. 125, nr 3/4

239--259

EN

Discrete tomography deals with tomographic reconstruction of greyscale images for which the set of possible grey levels is discrete and small. Here, we develop a discrete approximate reconstruction algorithm. Our algorithm computes an image that has only grey values belonging to a given finite set. It also guarantees that the difference between the given projections and the projections of the reconstructed discrete image is bounded. The bound, which is computable, is independent of the image size. We present reconstruction experiments for a range of phantom images and a varying number of grey values.

9

Implementation of variational level set methods and Chan-Vese model in electrical impedance tomography

Rymarczyk T., Filipowicz S. F., Sikora J.

Poznan University of Technology Academic Journals. Electrical Engineering

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2010

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No. 63

51-61

EN

The problem of the image reconstruction in Electrical Impedance Tomography (EIT) is a highly ill-posed inverse problem. The Chan-Vese method is an established model for numerical problems. In contrast to the traditional level set method, interfaces between the subdomains are represented as discontinuities in the level set function. Moreover, no more than one function is needed to represent any numbers of phases. The iterative algorithms are based a combination of the finite element method, level set methods, variational level set methods and Chan-Vese model.

10

Sztywne modele obciążenia w iteracyjnym algorytmie ruchomych obciążeń

Szaniec W.

Zeszyty Naukowe Politechniki Świętokrzyskiej. Nauki Techniczne

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2007

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Z. 2

149-166

PL

W pracy przedstawiono iteracyjny algorytm rozwiązywania równań kolokacyjnch ruchomych obciążeń dla sztywnych modeli pojazdów. Do opisu pojazdu wykorzystano MSES, konstrukcję modelowano elementami odkształcalnymi. Podukłady połączone są więziami sprężysto-tłumiącymi. Wykorzystano iteracyjną procedurę rozwiązywania problemu (1). Analizie poddano wpływ niektórych parametrów na zbieżność procesu. Potwierdzono wysoką skuteczność algorytmu dla przedstawionych obciążeń.

EN

The paper presents an iterative algorithm for the solution of moving loads collocation equations in rigid vehicle models. RFEM was used for the description, the construction was modelled by deformable elements. Subsystems were connected with elastic-damping bonds. The iterative procedure was used to solve the problem (1). The impact of some parameters on the process convergence was analysed. High effectiveness of the algorithm for the presented loads was confirmed.

11

Porównanie algorytmów minimalizacji w zastosowaniu do analizy złożonych sygnałów chromatograficznych

Ilewicz W.

Zeszyty Naukowe. Automatyka / Politechnika Śląska

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2006

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z. 144

171-178

PL

W artykule porównano 3 iteracyjne algorytmy minimalizacji, zaimplementowane w środowisku Matlab, w zastosowaniu do analizy złożonych sygnałów chromatograficznych metodą najmniejszych kwadratów: Gaussa-Newtona, Levenberga-Marquardta oraz metodą simplex Nedlera-Meada. Podstawowe kryteria porównania były następujące: czułość algorytmu na dokładność wstępnej oceny parametrów modelu, szybkość i zbieżność algorytmu oraz przydatność algorytmu do automatycznej analizy sygnałów chromatograficznych. Badania przeprowadzono metodami symulacyjnymi dla typowych modeli stosowanych w chromatografii.

EN

In article there are compared 3 iterative algorithms of minimization included in Matlab environment, for purpose of analysis of complex chromatographic signals. These are: Gauss-Newton method, Levenberg-Marquardt method and Nedler-Mead Simplex method. Basic criterions of comparison were sensitivity of method to starting parameter vector, speed, convergence of algorithms to proper solution and usefulness of algorithm to automatic analysis of chromatograms.

12

Poszukiwanie odpowiedniości elementów obrazów z wykorzystaniem niedokładnej odpowiedniości grafów

Bal A.

Zeszyty Naukowe. Automatyka / Politechnika Śląska

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2003

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z. 138

7-29

PL

W pracy przedstawiono dwa algorytmy - algorytm jednokrokowy i algorytm iteracyjny - pozwalające określić odpowiedniość obszarów obrazów stereo. Zadanie to realizowane jest poprzez poszukiwanie niedokładnej odpowiedniości grafów reprezentujących obrazy wejściowe. Do poszukiwania niedokładnej odpowiedniości grafów zastosowano zmodyfikowany algorytm poszukiwania największej kliki w odpowiednio zdefiniowanym grafie skojarzeniowym. Działanie algorytmów zaprezentowane zostało na symulowanych i rzeczywistych obrazach stereo.

EN

In this report two novel algorithms (one-step algorithm and iterative algorithm) for stereo image region matching are presented. Region matching is established by finding inexact matching of graphs that represented input images. For finding of inexact graph matching modified maximum clique finding algorithm is used. The tests results for simulated and real stereo images are also presented.

13

Asymptotic behavior of relatively nonexpansive operators in Banach spaces

Butnariu D., Reich S., Zaslavski A. J.

Journal of Applied Analysis

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2001

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Vol. 7, nr 2

151-174

EN

Let K be a closed convex subset of a Banach space X and let F be a nonempty closed convex subset of K. We consider complete metric spaces of self-mappings of K which fix all the points of F and are relatively nonexpansive with respect to a given convex function f on X. We prove (under certain assumptions on f) that the iterates of a generic mapping in these spaces converge strongly to a retraction onto F.

14

Nonlinear adaptive-parametric image restoration

Hrytskiv Z., Voloshynovskiy S.

Machine Graphics and Vision

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1998

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Vol. 7, No. 1/2

445-454

EN

In this paper the problem of restoration of defocused images corrupted by mixed noise is considered. To enhance the noise immunity of restoration algorithm based on iterative method with adaptive regularization and parametric constrains on the solution the prefiltering is proposed to be carried out. To avoid double images blurring on the prefiltering stage the simultaneous suppresion of gaussian and impulse noises is performed according to the local image structure using adaptive nonlinear filter.

15

Set-valued implicit Wiener-Hopf equations and generalized strongly nonlinear quasivariational inequalities

Ding X. P.

Journal of Applied Analysis

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1998

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Vol. 4, nr 1

75-87

EN

In this paper, we study a class of generalized strongly nonlinear quasivariational inequality problem (GSNQVIP(T,A,g,D,K(x))) which include the most of quasivariational inequalities and quasicomplementarity problems as special cases. We prove that the generalized strongly nonlinear quasivariational inequality problem is equivalent to solving the set-valued implicit Wiener-Hopf equation. By using the equivalence, a new iterative algorithm for finding the approximate solutions of the generalized strongly nonlinear quasivariational inequality problems are suggested and analyzed. The convergence criteria for the algorithm is also discussed. These new results include many known results for generalized quasivariational inequalities and generalized quasicomplementarity problems as special cases.