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1
Content available remote Analysis of application of gradient concrete models to assess concrete cover degradation under reinforcement corrosion
Yurkova Kseniya, Krykowski Tomasz
Architecture Civil Engineering Environment
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2023
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Vol. 16, no. 4
109--123
EN
The paper presents a comparative analysis of the application of two nonlocal gradient-formulated models to evaluate the concrete cover degradation time. Calculations were made taking into account the increase in the volume of the steel ring around the perimeter of the reinforcement bar. The results of the calculations were compared with the results of experimental studies published in the literature and with the elastic-plastic model based on the Menetrey-Willam surface, in which the objectivity of the obtained results depends on the fracture energy. In addition, the paper compares solutions using different contact models and cohesion models.
2
Content available Segmentation of images using gradient methods and polynomial approximation
Piekar E., Momot M., Momot A.
Journal of Medical Informatics & Technologies
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2014
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Vol. 23
95--102
EN
The paper presents a method for segmentation of images using region growing, with modification through the use of a correction coefficient based on the variation of intensity (brightness) in the neighborhood of the pixel of the interest. A method for the quantification of variability is based on differences in intensity, as well as the differences in intensity gradients in the surrounding pixels [10]. Evaluation of the gradients were determined by means of numerical differentiation, using the polynomial approximation [11]. The article presents the effects of application of developed methods for segmentation of images of the brain, lungs and heart.
3
Content available remote A New Non-monotone Line Search Algorithm for Nonlinear Programming
Zhang J.
Przegląd Elektrotechniczny
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2012
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R. 88, nr 7b
265--268
EN
We study the application of a kind of non-monotone line search’s technique in conjugate gradient method. At present, most of the study of conjugate gradient methods are using Wolfe’s monotone line search, by constructing the condition of Zoutendijk, we can get the conclusion that it’s convergence by using reduction to absurdity. Here we study the global convergence of conjugate gradient methods with Armijo-type line search, the thought of proof wasn’t using the method above mentioned.
PL
Przeprowadzono studia nad zastosowaniem niemonotonicznego badania prostej w sprzężonej metodzie gradientowej. Obecnie najczęściej wykorzystuje się metodę Wolfa ale nasze badania wykazały że lepsze wyniki uzyskuje się w metodach globalnej zbieżności sprzężonej metody gradientowej.
4
Content available Symulacja i testowanie algorytmów wykrywania krawędzi na potrzeby lotu wśród kanionu ulicy
Bogdan M.
Acta Mechanica et Automatica
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2010
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Vol. 4, no. 3
9-15
PL
W artykule testowano i analizowano metody wykrywania krawędzi w środowisku programowym Matlab’a. Skupiono się głownie na metodach gradientowych. W celu uproszczenie informacji zawartej w zarejestrowanych obrazach (klatkach) zaproponowano, także opis analityczny wykrywanych krawędzi – przeszkód (transformata Hough’a).
EN
In the article the methods for edge detection in the Matlab’s software environment were tested and analyzed. The primary focus is placed on the gradient methods. In order to simplify the information comprised in the registered images (frames) an analytical description of the detected edge-obstacles was proposed (Hough's transform).
5
Content available remote Gradient method of cast iron latent heat identification
Majchrzak E., Mendakiewicz J.
Archives of Foundry Engineering
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2007
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Vol. 7, iss. 4
121-126
EN
In the paper the cast iron latent heat in the form of three components corresponding to solidification of austenite and eutectic phases is identified. The basic information concerning the form of adequate functions approximation has been taken on the basis of cooling curve and temperature derivative courses found by means of the TDA technique. On the stage of inverse problem solution the gradient method has been used. The numerical computations have been done using the finite difference method. In the final part of the paper the example of latent heat identification is shown.
6
Optimum design of aircraft thin-walled structures
Safronov V., Turkin I.
Research Bulletin / Warsaw University of Technology, Institute of Aeronautics and Applied Mechanics
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2001
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nr 12
69-72
EN
The optimum design methodology of aircraft thin-walled shell structures at complex loading is presented in this article. The optimization of a thin'walled structure is performed to criterion of minor mass with using of the developed modified method for gradient projection on strength, stability and reliability of a thin-walled structure in statics and dynamics, and also in view of technological and operational limitations. The results of a sample test are shown in this article as well.
7
Content available remote Comparison of gradient and gradientless methods of the dynamic estimation of static scherbius drive parameters
Beniak R.
Zeszyty Naukowe. Elektryka / Politechnika Łódzka
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1998
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z. 91
189--194
EN
The main aim of the paper is the comparison of two different methods of dynamic estimation. First of them is gradientless Jeeves & Hook method. The second one is widely known as Davidon & Fletcher & Powel method. These methods have been used for estimation of the parameters of the mathematical model of the static Scherbius drive. Therefore the paper describes the model of the drive and results of numerical tests. The practical results of the estimation are quite positive for both methods. This means that for the dynamic estimation of parameters of the drive considered methods are equivalent.
PL
Artykuł przedstawia porównanie metod estymacji dynamicznej parametrów kaskady przekształtnikowej stałego momentu. Porównywane są metody: Jeevesa - Hooka i Dawidona - Fletchera - Powela. Pierwsza z nich jest przedstawicielem metod bezgradientowych, a druga jest szeroko znaną metodą gradientową. W referacie zamieszczono: opis napędu, rezultaty testów porównawczych, przeprowadzonych przy wykorzystaniu modelu matematycznego kaskady oraz porównanie metod estymacji w warunkach praktycznych. Przeprowadzone testy pokazały, że w analizowanym przypadku badane metody charakteryzują się porównywalną efektywnością.
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