Wyniki wyszukiwania - BazTech

1

Evolutionary stable strategies in networked games: the influence of topology

Kasthurirathna D., Piraveenan M., Uddin S.

Journal of Artificial Intelligence and Soft Computing Research

|

2015

|

Vol. 5, No. 2

83--95

EN

Evolutionary game theory is used to model the evolution of competing strategies in a population of players. Evolutionary stability of a strategy is a dynamic equilibrium, in which any competing mutated strategy would be wiped out from a population. If a strategy is weak evolutionarily stable, the competing strategy may manage to survive within the network. Understanding the network-related factors that affect the evolutionary stability of a strategy would be critical in making accurate predictions about the behaviour of a strategy in a real-world strategic decision making environment. In this work, we evaluate the effect of network topology on the evolutionary stability of a strategy. We focus on two well-known strategies known as the Zero-determinant strategy and the Pavlov strategy. Zero-determinant strategies have been shown to be evolutionarily unstable in a well-mixed population of players. We identify that the Zero-determinant strategy may survive, and may even dominate in a population of players connected through a non-homogeneous network. We introduce the concept of ‘topological stability’ to denote this phenomenon. We argue that not only the network topology, but also the evolutionary process applied and the initial distribution of strategies are critical in determining the evolutionary stability of strategies. Further, we observe that topological stability could affect other well-known strategies as well, such as the general cooperator strategy and the cooperator strategy. Our observations suggest that the variation of evolutionary stability due to topological stability of strategies may be more prevalent in the social context of strategic evolution, in comparison to the biological context.

2

Investigation of harmonic generation from dimmable LED lamps

Uddin S., Shareef H., Hannah M.A., Mohamed A.

Przegląd Elektrotechniczny

|

2013

|

R. 89, nr 4

151-155

EN

The purpose of this paper is to investigate harmonic generation from dimmable Light Emitting Diode lamps (LEDs) which are used in residential and commercial applications as an energy efficient lighting systems. It is done by conducting laboratory tests on various LED lamps and tapping the load current behavior under different conditions. Then the frequency domain analysis is performed to investigate the generated harmonics. Harmonic levels of different wattage, various branded dimmable and non dimmable LED bulbs along with dimmable compact fluorescent lamps are experimentally evaluated and compared. Experimental result shows that, all LED lamps generate very high level of harmonic during dimming operation which may affect the power quality of AC mains.

PL

W artykule opisano zagadnienie emisji harmonicznych przez ściemnianą diodę LED, wykorzystywaną do oświetlania pomieszczeń. Przeprowadzono próby laboratoryjne w różnych warunkach pracy, a na ich podstawie analizy generowanych harmonicznych. Pod tym kątem dokonano porównania działania badanych diod z innymi energooszczędnymi rozwiązaniami.

3

Phase, microstructure and dielectric properties of 0.94Bi0.5Na0.5TiO3-0.06BaTiO3 ceramics prepared by sol-gel technique

Uddin S., Iqbal Y., Ullah A.

Materials Science Poland

|

2013

|

Vol. 31, No. 3

410--414

EN

0.94Bi0.5Na0.5TiO3-0.06BaTiO3 ceramics were fabricated by sol-gel technique. The XRD results revealed the formation of a single phase perovskite structured Bi0.5Na0.5TiO3-BaTiO3 at 600 °C. The SEM images showed dense microstructure and the optimum density of the ceramics sintered at 1100 °C was 5.2 g/cm3. The saturation polarization (P s ) was found to be increased with increasing temperature while the remnant polarization (P r ) was found to be increased gradually and then decreased abruptly near 85 °C, which could be attributed to the phase transformation. The coercive electric field (E c ) was found to be decreased gradually with increasing temperature. The maximum value of dielectric constant (ɛ r ) at room temperature was 800 and dielectric loss at 1 MHz was 0.07.

4

Harmonics and thermal characteristics of low wattage LED lamps

Uddin S., Shareef H., Mohamed A., Hannan M.A.

Przegląd Elektrotechniczny

|

2012

|

R. 88, nr 11a

266-271

EN

This paper presents harmonics and thermal characteristic of Light Emitting Diode (LEDs) Lamps which are used in residential and commercial applications as energy efficient lighting bulbs. It is done by performing experimental tests on various LED lamps available in the market. The current drawn by several LED lamps are first measured to investigate the electrical characteristics. These measurements provide current harmonic characteristic of individual lamps. Then various configurations of LEDs were connected to a laboratory scale feeder to analyze the diversity factors. Furthermore, heat generation levels of the tested LED lamps are investigated to measure the thermal characteristics of LED lamps. The results show that individual LED bulbs produce considerable amount of harmonics but it could be reduced by combining various types of LED bulbs. Furthermore, the diversity factor could be improved if LED lamps are mixture with Compact Fluorescent Lamps (CFLs). Results also shows that the thermal characteristic of LED lamps is much better compare to the performance of CFLs.

PL

W artykule przedstawiono analizę harmonicznych oraz charakterystyki termiczne żarówek z diodami LED, stosowanymi komercyjnie w lampach. Badania przeprowadzono na losowo wybranych lampach dostępnych na rynku. Wskazano rozwiązania mogące zredukować ilość generowanych harmonicznych.