Wyniki wyszukiwania - Biblioteka Nauki

1

Iteracyjna metoda obliczania odciągów masztów

100%

Pałkowski S.

Inżynieria i Budownictwo

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2001

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tom R. 57, nr 4

239-240

PL

Przedstawiono prostą metodę iteracyjną obliczania odciągów. Przeprowadzono analizę parametryczną odciągu, na której podstawie określono zakres ważności przybliżonych rozwiązań.

EN

A simple method for iterative calculation of mast guys is shown. The parametric study of a mast guy is presented.

2

Projektowanie działek metodą iteracyjną

100%

Zygmunt M.

|

2010

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nr 03

PL

Artykuł porusza problem projektowania działek na zadaną wartość metodą kolejnych przybliżeń. Autor zwraca uwagę na możliwość osiągnięcia końcowego wyniku, przeprowadzając z góry określoną ilość iteracji. Dla większości przypadków maksymalna ich ilość nie przekracza 17. Odnosi się także do uniwersalności tej metody projektowania. Jest ona niezależna od kształtu poszukiwanej granicy i kierunku projektowania. Może być użyta do projektowania ortogonalnego jak i biegunowego.

EN

The article touches upon a question about creating parcels for set value while using the iteration method. The author describes the possibility of achieving a final result, making the beforehand defined amount of iterations. For a majority of cases their amount doesn't surpass 17. It also refers to the universality of this method. A shape of a border that we are looking for and direction of planning aren't important in this method. It also can be used in orthogonal or angular planning.

3

Design of foundation rafts by uncoupled iterative method

100%

Tornyos A. , Czap Z.

Computer Assisted Mechanics and Engineering Sciences

|

1999

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tom Vol. 6, No. 1

27-37

EN

The authors developed a calculation module into a commercial finite element analysis (FEA) program, which is capable of calculating foundation rafts quickly, with correct results for the engineering practice. The calculation method is based on the so-called 'uncoupled iterative method', wherein the structure and the soil continuum are analysed separately. The results of one analysis form the boundary conditions for the subsequent analysis as part of an iterative process.The connection between the raft and the soil is considered to be represented by the bedding modulus of the raft and by the soil stresses. The method provides the same displacements for the raft as for the soil surface, provided sufficient convergence can be reached if the raft is not elevated from the soil.

4

Własności niezupełnego rozkładu LDLt w iteracyjnych rozwiązań równań MES

75%

Kazberuk A. , Tribiłło R.

Zeszyty Naukowe Politechniki Białostockiej. Budownictwo

|

2000

|

tom Z.20

63-68

PL

W pracy przedstawiono niektóre aspekty stosowania metody gradientów sprzężonych do rozwiązywania dużych układów równań liniowych metodą elementów skończonych. Wykazano atrakcyjność stosowania schematów iteracyjnych w stosunku do metod bezpośrednich oraz przeanalizowano wpływ uporządkowania układu równań na szybkość zbieżności iteracji.

EN

The efficiency of the preconditioned conjugate gradient method applied to solving large sparse linear equation derived from finite element method has been studied.

5

Równoległa implementacja metod iteracyjnych dla układu równań z macierzami rzadkimi

75%

Schubring T.

TTS Technika Transportu Szynowego

|

2013

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tom R. 20, nr 10

499--505, CD

PL

W artykule podano równoległą implementację metod rozwiązywania układu równań liniowych z macierzą rzadką w języku programowania UPC (Unified Parallel C). Uwzględniono możliwości środowiska programistycznego Berkeley UPC oraz format spakowanych wierszy CSR (Compressed Sparse Row).

EN

Paper described a parallel implementation of the iterative methods for solving linear equation systems with sparse matrix in the UPC programming language (Unified Parallel C). Possibilities of the Berkeley UPC development environment and the CSR packed rows format (Compressed Sparse Row) were included.

6

On The Two-Step Iterative Method of Solving Frictional Contact Problems in Elasticity

75%

Angelov T. A. , Liolios A. A.

International Journal of Applied Mathematics and Computer Science

|

2005

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tom Vol. 15, no 2

197-203

EN

A class of contact problems with friction in elastostatics is considered. Under a certain restriction on the friction coefficient, the convergence of the two-step iterative method proposed by P.D. Panagiotopoulos is proved. Its applicability is discussed and compared with two other iterative methods, and the computed results are presented.

7

System matrix computation for iterative reconstruction algorithms in SPECT based on direct measurements

75%

Borys D. , Szczucka-Borys K. , Gorczewski K.

International Journal of Applied Mathematics and Computer Science

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2011

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tom Vol. 21, no 1

193-202

EN

A method for system matrix calculation in the case of iterative reconstruction algorithms in SPECT was implemented and tested. Due to a complex mathematical description of the geometry of the detector set-up, we developed a method for system matrix computation that is based on direct measurements of the detector response. In this approach, the influence of the acquisition equipment on the image formation is measured directly. The objective was to obtain the best quality of reconstructed images with respect to specified measures. This is indispensable in order to be able to perform reliable quantitative analysis of SPECT images. It is also especially important in non-hybrid gamma cameras, where not all physical processes that disturb image acquisition can be easily corrected. Two experiments with an 131I point source placed at different distances from the detector plane were performed allowing the detector response to be acquired as a function of the point source distance. An analytical Gaussian function was fitted to the acquired data in both the one- and the two-dimensional case. A cylindrical phantom filled with a water solution of 131I containing a region of 'cold' spheres as well as a uniform solution (without any spheres) was used to perform algorithm evaluation. The reconstructed images obtained by using four different of methods system matrix computation were compared with those achieved using reconstruction software implemented in the gamma camera. The contrast of the spheres and uniformity were compared for each reconstruction result and also with the ranges of those values formulated by the AAPM (American Association of Physicists in Medicine). The results show that the implementation of the OSEM (Ordered Subsets Expectation Maximization) algorithm with a one-dimensional fit to the Gaussian CDR (Collimator-Detector Response) function provides the best results in terms of adopted measures. However, the fit of the two-dimensional function also gives satisfactory results. Furthermore, the CDR function has the potential to be applied to a fully 3D OSEM implementation. The lack of the CDR in system matrix calculation results in a very noisy image that cannot be used for diagnostic purposes.

8

On rational functions related to algorithms for a computation of roots. II

75%

Baran M.

Science, Technology and Innovation

|

2019

|

tom Vol. 7, no. 4

26--29

EN

We discuss a nice composition properties related to algorithms for computation of N-roots. Our approach gives direct proof that a version of Newton's iterative algorithm is of order 2. A basic tool used in this note are properties of rational function Φ(w; z) = z-w/(z+w), which was used earlier in [1] in the case of algorithms for computations of square roots.

9

Algorytmy równoległe w języku programowania C#

75%

Schubring T.

TTS Technika Transportu Szynowego

|

2016

|

tom R. 23, nr 12

196--199

PL

W artykule opisano możliwość łatwego implementowania równoległych algorytmów w języku programowania C# . Zwrócono szczególną uwagę na zastosowanie metody For klasy Parallel dostępnej na platformie Microsoft.NET.

EN

The article describes the ability to easily implement parallel algorithms in the C# programming language. Special attention was paid to the application of the method For class Parallel available on the Microsoft .NET platform.

10

Performance evaluation of iterative methods to unconstrained single variable minimization problems

75%

Horla D.

Studia z Automatyki i Informatyki

|

2013

|

tom T. 38

7--33

EN

The paper considers performance issues of a class of iterative minimization methods of unconstrained single variable problems. Problem structures that assure superior performance of a specific method have been stipulated with appropriate conclusions drawn.

PL

W artykule poruszono zagadnienie szybkości działania metod minimalizacji funkcji jednej zmiennej dla zadań programowania nieliniowego bez ograniczeń. Wskazano przypadki, dla których konkretna metoda działa szybciej niż pozostałe oraz wyciągnięto wnioski odnośnie takiego stanu rzeczy.

11

Some variant of iteration method for infinite systems of parabolic differential-functional equations

75%

Brzychczy S.

Opuscula Mathematica

|

2000

|

tom Vol. 20

41-50

EN

We consider the Fourier first boundary value problem for an infinite system of weakly coupled nonlinear differential-functional equations of parabolic type. The right-hand sides of the system are functionals of unknown functions and this system being thus essentially coupled by the functional argument. To prove the existence and uniqueness of solution to this problem, we shall apply some variant of monotone iterative method. This variant of successive approximations by pseudo-linearization of the nonlinear problem has been introduced by T. Ważewski.

PL

W pracy rozważany jest pierwszy problem brzegowy Fouriera dla nieskończonego słabo sprzężonego układu równań różniczkowo- -funkcjonalnych typu parabolicznego. Prawe strony tego układu zależą w sposób funkcjonalny od poszukiwanego rozwiązania i układ jest sprzężony poprzez argument funkcjonalny. Do dowodu istnienia i jednoznaczności zastosowano pewien wariant monotonicznej metody iteracyjnej. Taka metoda konstrukcji ciągów kolejnych przybliżeń poprzez pseudo-linearyzację problemu nieliniowego została zaproponowana przez T. Ważewskiego.

12

Inequality-Based Approximation of Matrix Eigenvectors

63%

Kocsor A. , Dombi J. , Balint I.

International Journal of Applied Mathematics and Computer Science

|

2002

|

tom Vol. 12, no 4

533-538

EN

A novel procedure is given here for constructing non-negative functions with zero-valued global minima coinciding with eigenvectors of a general real matrix A. Some of these functions are distinct because all their local minima are also global, offering a new way of determining eigenpairs by local optimization. Apart from describing the framework of the method, the error bounds given separately for the approximation of eigenvectors and eigenvalues provide a deeper insight into the fundamentally different nature of their approximations.

13

Control of chaos in the burke-shaw system of fractal-fractional order in the sense of Caputo-Fabrizio

63%

Saber S.

|

tom Vol. 23, nr 1

83-96

EN

For the Burke-Shaw system, we propose a fractal-fractional order in the sense of the Caputo-Fabrizio derivative. The proposed system is solved by utilizing the fractal-fractional derivative operator with an exponential decay kernel. Time-fractional Caputo-Fabrizio fractal fractional derivatives are applied to the Burke-Shaw-type nonlinear chaotic systems.Based on fixed point theory, it has been demonstrated that a fractal-fractional-order model under the Caputo-Fabrizio operator exists and is unique. Using a numerical power series method, we solve the fractional Burke-Shaw model. Using Newton’s interpolation polynomial, we solve the equation numerically by implementing a novel numerical scheme based on an efficient polynomial.

14

Zagadnienia odwrotne przewodzenia ciepła w zastosowaniu do wyznaczania charakterystyk materiałów

63%

Ignaszak Z. , Kamiński H. , Sypniewska-Kamińska G.

Archiwum Odlewnictwa

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2001

|

tom R. 1, nr 2

144--154

PL

W artykule przedstawiono przykłady praktycznych sposobów rozwiązywania zagadnień odwrotnych znajdujące zastosowanie do wyznaczania cieplnych charakterystyk materiałów. Podano założenia, sformułowania oraz przeprowadzono analizę iteracyjnych i bezpośrednich metod rozwiązywania tych zagadnień. Wskazano na potrzebę rozwoju tych metod w powiązaniu z metodyką pieczołowicie przeprowadzonego eksperymentu.

EN

In the paper the examples of practical solutions of inverse problem methods applied to thermal material data determination are presented. The assumptions and rules and also analyses of iterative and direct methods are shown. It is indicated that the development of those methods, connected with careful experiment methodology, are needed.

15

Optimal modelling of steel multi-span beams using the gradient-iterative method

63%

Mikulski L.

|

2019

|

tom Vol. 29, no. 4

112--127

EN

The article describes the gradient-iterative optimization method and outlines the method’s basic assumptions and illustrates its general use. The method’s implementation was illustrated based on a steel I-beam. The described calculation example concerns the optimization of the height of the web of a multi-span beam. The method enables finding an optimal solution with the use of simple and commonly available software. To illustrate the effectiveness of the optimization method, multiple calculations were performed for beams with various spans and various load conditions.

16

Numerical stability of the Richardson second order method

63%

Smoktunowicz A. , Wróbel I.

|

2005

|

tom Vol. 38, nr 1

255--263

EN

In this paper we study numerical properties of the Richardson second order method (RS) for solving a linear system Ax = b, where A € Rnxn is infinitysymmetric and positive definite. We consider the standard model of floating point arithmetic (cf. [6], [7], [11]). We prove that the RS-algorithm is numerically stable. This means that the algorithm computes approximations xk to the exact solution x* = A-1b such that the error limfk||xk - x*ll2 ls of order eMcond(A), where eM is the machine precision and cond(A) = ||A || 2 ||A-1|| denotes the condition number of the matrix A.

17

On rational functions related to algorithms for a computation of roots. I

63%

Baran M.

Science, Technology and Innovation

|

2019

|

tom Vol. 7, no. 4

17--25

EN

We discuss a less known but surprising fact: a very old algorithm for computing square root known as the Bhaskara-Brouncker algorithm contains another and faster algorithms. A similar approach was obtained earlier by A.K. Yeyios [8] in 1992. By the way, we shall present a few useful facts as an essential completion of [8]. In particular, we present a direct proof that k – th Yeyios iterative algorithm is of order k. We also observe that Chebyshev polynomials Tn and Un are a special case of a more general construction. The most valuable idea followed this paper is contained in applications of a simple rational function Φ(w; z) = z-w/z+w.

18

Doświadczenia z projektowania i produkcji betonów architektonicznych na bazie produktów RECKLI

63%

Wójcik A.

|

tom nr 9

21--22

19

Quartic non-polynomial spline solution for solving two-point boundary value problems by using Conjugate Gradient iterative method

63%

Justine H. , Chew J. V. L. , Sulaiman J.

Journal of Applied Mathematics and Computational Mechanics

|

2017

|

tom Vol. 16, nr 1

41--50

EN

Solving two-point boundary value problems has become a scope of interest among many researchers due to its significant contributions in the field of science, engineering, and economics which is evidently apparent in many previous literary publications. This present paper aims to discretize the two-point boundary value problems by using a quartic non-polynomial spline before finally solving them iteratively with Conjugate Gradient (CG) method. Then, the performances of the proposed approach in terms of iteration number, execution time and maximum absolute error are compared with Gauss-Seidel (GS) and Successive Over-Relaxation (SOR) iterative methods. Based on the performances analysis, the two-point boundary value problems are found to have the most favorable results when solved using CG compared to GS and SOR methods.

20

An iterative method for symmetric positive semidefinite linear system of equations

63%

Salkuyeh D. K.

Demonstratio Mathematica

|

2014

|

tom Vol. 47, nr 2

482--492

EN

In this paper, a new two-step iterative method for solving symmetric positive semidefinite linear system of equations is presented. A sufficient condition for the semiconvergence of the method is also given. Some numerical experiments are presented to show the efficiency of the proposed method.