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Abstrakt

O tym, jak rozmawiać o przyszłości, której być może nie będzie, opowiada dr Paweł Mościcki z Instytutu Badań Literackich PAN.
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Abstrakt

Visible Light Communication (VLC) is a technique for high-speed, low-cost wireless data transmission based on LED luminaries. Wireless LAN environments are a major application of VLC. In these environments, VLC is used in place of traditional systems such as Wi-Fi. Because of the physical characteristics of visible light, VLC is considered to be superior to traditional radio-based communication in terms of security. However, as in all wireless systems, the security of VLC with respect to eavesdropping, signal jamming and modification must be analyzed. This paper focuses on the aspect of jamming in VLC networks. In environments where multiple VLC transmitters are used, there is the possibility that one or more transmitters will be hostile (or “rogue”). This leads to communication disruption, and in some cases, the hijacking of the legitimate data stream. In this paper we present the theoretical system model that is used in simulations to evaluate various rogue transmission scenarios in a typical indoor environment. The typical approach used so far in jamming analysis assumes that all disruptive transmissions may be modeled as Gaussian noise, but this assumption may be too simplistic. We analyze and compare two models of VLC jamming: the simplified Gaussian and the exact model, where the full characteristics of the interfering signal are taken into account. Our aim is to determine which methodology is adequate for studying signal jamming in VLC systems.
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Słowa kluczowe biomass coal ash chlorine slagging

Abstrakt

Preliminary lab-scale investigations were conducted on slagging abatement in biomass-firing by fuel mixing. Three agriculture biomass fuels and olive cake were used in the experiments. Polish lignites and bituminous coals were examined as anti-sintering additives. The effects of chlorine release, potassium retention and ash sintering were examined by heating samples of biomass fuels and additives in the muffle oven and, next, firing them in the laboratory down-fired furnace at the temperature in the range of 800-1150ºC. The obtained slag samples were analysed on: chlorine and potassium content, sintering tendency and crystalline components. Among the examined coals lignite from Turów mine and bituminous coal from Bolesław Śmiały mine appeared to be the most effective in potassium retention in aluminosilicate and chlorine release from slag. Possibly the major factor of these coals which reduced ash sintering was relatively high content of kaolinite
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