Parametry drgań belki z cieczami MR o różnej zawartości cząstek ferromagnetycznych

The study presents the results of laboratory studies on free vibrations of sandwich beams filled with magnetorheological (MR) fluids characterised by various proportions of ferromagnetic particles by weight. Based on the obtained results, it was possible to determine the impact of the content of the particles in question on the natural frequency of free vibrations and the dimensionless damping coefficient of beam.W pracy przedstawiono wyniki badań laboratoryjnych drgań swobodnych trójwarstwowych belek wypełnionych cieczami magnetoreologicznymi (MR) o różnej zawartości wagowej cząstek ferromagnetycznych. Na podstawie uzyskanych wyników określono wpływ zawartości tych cząstek na podstawową częstotliwość drgań własnych i bezwymiarowy współczynnik tłumienia belki

Neighbour and network discovery in cognitive radio networks: research activities and results in the ACROPOLIS Network of Excellence

Cognitive radio networks operation relies on the capability to gather information about the surrounding environment, as regards both internal network status (presence and capabilities of other devices belonging to the same network) and external systems potentially coexisting with the cognitive network. In particular, retrieving information at the local level is a function required to all wireless networks, and goes under the name of neighbour discovery. Under this aspect, cognitive networks make no exception. Similarly, cognitive networks share with traditional wireless networks the necessity of a function for retrieving and exchanging information on a network wide scale, referred to in the following as network discovery. The definition of efficient neighbour and network discovery strategies for cognitive networks, taking into account their specific characteristics, is one of the goals of the research activities undergoing within the framework of the ACROPOLIS NoE. In this work, neighbour and network discovery solutions currently under investigation within the ACROPOLIS joint research activities are presented, and future research lines are identified. The paper first presents algorithms and results on neighbour discovery and Medium Access Control, and moves then to network wide protocols by presenting the work carried out in ACROPOLIS on routing for underlay cognitive networks. The paper provides then an overview on the common simulation platform developed within ACROPOLIS to investigate neighbour and network discovery, and finally discusses future research directions on such topics. © VDE VERLAG GMBH