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Wyszukujesz frazę "Van, T. T." wg kryterium: Autor


Wyświetlanie 1-4 z 4
Tytuł:
Content-based image retrieval using a signature graph and a self-organizing map
Autorzy:
Van, T. T.
Le, T. M.
Powiązania:
https://bibliotekanauki.pl/articles/330159.pdf
Data publikacji:
2016
Wydawca:
Uniwersytet Zielonogórski. Oficyna Wydawnicza
Tematy:
binary signature
similarity measure
signature graph
image retrieval
sygnatura binarna
miara podobieństwa
wyszukiwanie obrazu
Opis:
In order to effectively retrieve a large database of images, a method of creating an image retrieval system CBIR (content-based image retrieval) is applied based on a binary index which aims to describe features of an image object of interest. This index is called the binary signature and builds input data for the problem of matching similar images. To extract the object of interest, we propose an image segmentation method on the basis of low-level visual features including the color and texture of the image. These features are extracted at each block of the image by the discrete wavelet frame transform and the appropriate color space. On the basis of a segmented image, we create a binary signature to describe the location, color and shape of the objects of interest. In order to match similar images, we provide a similarity measure between the images based on binary signatures. Then, we present a CBIR model which combines a signature graph and a self-organizing map to cluster and store similar images. To illustrate the proposed method, experiments on image databases are reported, including COREL, Wang and MSRDI.
Źródło:
International Journal of Applied Mathematics and Computer Science; 2016, 26, 2; 423-438
1641-876X
2083-8492
Pojawia się w:
International Journal of Applied Mathematics and Computer Science
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Two implementations of the preconditioned conjugate gradient method on heterogeneous computing grids
Autorzy:
Collignon, T. P.
Van Gijzen, M. B.
Powiązania:
https://bibliotekanauki.pl/articles/907778.pdf
Data publikacji:
2010
Wydawca:
Uniwersytet Zielonogórski. Oficyna Wydawnicza
Tematy:
przetwarzanie siatkowe
system liniowy
metoda iteracyjna
gradient sprzężony
przepływ pęcherzykowy
grid computing
large sparse linear systems
iterative methods
conjugate gradient method
Chronopoulos/Gear CG
GridSolve middleware
bubbly flows
Opis:
Efficient iterative solution of large linear systems on grid computers is a complex problem. The induced heterogeneity and volatile nature of the aggregated computational resources present numerous algorithmic challenges. This paper describes a case study regarding iterative solution of large sparse linear systems on grid computers within the software constraints of the grid middleware GridSolve and within the algorithmic constraints of preconditioned Conjugate Gradient (CG) type methods. We identify the various bottlenecks induced by the middleware and the iterative algorithm. We consider the standard CG algorithm of Hestenes and Stiefel, and as an alternative the Chronopoulos/Gear variant, a formulation that is potentially better suited for grid computing since it requires only one synchronisation point per iteration, instead of two for standard CG. In addition, we improve the computation-to-communication ratio by maximising the work in the preconditioner. In addition to these algorithmic improvements, we also try to minimise the communication overhead within the communication model currently used by the GridSolve middleware. We present numerical experiments on 3D bubbly flow problems using heterogeneous computing hardware that show lower computing times and better speed-up for the Chronopoulos/Gear variant of conjugate gradients. Finally, we suggest extensions to both the iterative algorithm and the middleware for improving granularity.
Źródło:
International Journal of Applied Mathematics and Computer Science; 2010, 20, 1; 109-121
1641-876X
2083-8492
Pojawia się w:
International Journal of Applied Mathematics and Computer Science
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Robust Predictive Control Using a Time-Varying Youla Parameter
Autorzy:
Van den Boom, T. J. J.
De Vries, R. A. J.
Powiązania:
https://bibliotekanauki.pl/articles/908311.pdf
Data publikacji:
1999
Wydawca:
Uniwersytet Zielonogórski. Oficyna Wydawnicza
Tematy:
sterowanie predykcyjne
stabilność
niezawodność
predictive control
Youla parametrization
stability
robustness
Opis:
In this paper, a standard predictive control problem (SPCP) is formulated, which consists of one extended process description with a feedback uncertainty block. The most important finite horizon predictive control problems can be seen as special realizations of this SPCP. The SPCP and its solution are given in a state-space form. The objective of the controller is a nominal performance subject to signal constraints and robust stability with respect to a 1-norm bounded model uncertainty. The optimal controller consists of a feedforward part for nominal signal tracking and a feedback part for disturbance rejection and model error compensation. The feedforward part is realized by the predictive controller for the nominal disturbance-free case. The feedback part of the controller is realized by using the Youla parametrization. The Youla parameter is optimized at every sample time in a receding horizon setting to cope with signal constraints and (robust stability) constraints on the operator itself.
Źródło:
International Journal of Applied Mathematics and Computer Science; 1999, 9, 1; 101-128
1641-876X
2083-8492
Pojawia się w:
International Journal of Applied Mathematics and Computer Science
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Joint queue-perturbed and weakly coupled power control for wireless backbone networks
Autorzy:
Olwal, T. O.
Djouani, K.
Kogeda, O. P.
van Wyk, B. J.
Powiązania:
https://bibliotekanauki.pl/articles/330956.pdf
Data publikacji:
2012
Wydawca:
Uniwersytet Zielonogórski. Oficyna Wydawnicza
Tematy:
sterowanie mocą
sterowanie rozproszone
sieć szkieletowa
sterowanie optymalne
decentralized power control
singular perturbation theory
weak coupling theory
wireless backbone networks
optimal control theory
Opis:
Wireless Backbone Networks (WBNs) equipped with Multi-Radio Multi-Channel (MRMC) configurations do experience power control problems such as the inter-channel and co-channel interference, high energy consumption at multiple queues and unscalable network connectivity. Such network problems can be conveniently modelled using the theory of queue perturbation in the multiple queue systems and also as a weak coupling in a multiple channel wireless network. Consequently, this paper proposes a queue perturbation and weakly coupled based power control approach for WBNs. The ultimate objectives are to increase energy efficiency and the overall network capacity. In order to achieve this objective, a Markov chain model is first presented to describe the behaviour of the steady state probability distribution of the queue energy and buffer states. The singular perturbation parameter is approximated from the coefficients of the Taylor series expansion of the probability distribution. The impact of such queue perturbations on the transmission probability, given some transmission power values, is also analysed. Secondly, the inter-channel interference is modelled as a weakly coupled wireless system. Thirdly, Nash differential games are applied to derive optimal power control signals for each user subject to power constraints at each node. Finally, analytical models and numerical examples show the efficacy of the proposed model in solving power control problems in WBNs.
Źródło:
International Journal of Applied Mathematics and Computer Science; 2012, 22, 3; 749-764
1641-876X
2083-8492
Pojawia się w:
International Journal of Applied Mathematics and Computer Science
Dostawca treści:
Biblioteka Nauki
Artykuł
    Wyświetlanie 1-4 z 4

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