The Impact of Sensing Range on Spatial-Temporal Opportunity

In this paper, we study the impact of secondary user (SU) sensing range on spectrum access opportunity in cognitive radio networks. We first derive a closed-form ex- pression of spectrum access opportunity by taking into ac- count the random variations in number, locations and trans- mitted powers of primary users (PUs). Then, we show how SU sensing range affects spectrum access opportunity, and the tradeoff between SU sensing range and spectrum ac- cess opportunity is formulated as an optimization problem to maximize spectrum access opportunity. Furthermore, we prove that there exists an optimal SU sensing range which yields the maximum spectrum access opportunity, and nu- merical results validate our theoretical analysis

Light-weight wood-magnesium oxychloride cement composite building products made by extrusion

This is the post-print version of the final paper published in Construction and Building Materials. The published article is available from the link below. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reflected in this document. Changes may have been made to this work since it was submitted for publication. Copyright @ 2011 Elsevier B.V.Magnesium oxychloride (MOC) cement is a type of non-hydraulic cement with yellowish color in nature and low alkalinity exhibiting many other properties superior to Portland Cement (PC). In this study, light-weight wood–MOC cement composite building products, with sawdust and/or perlite as aggregate, were made through extrusion. Physical, nailing and mechanical properties of these composites were investigated. It was found that the specific dry densities of the wood–MOC cement composites were close to 1.0 and they were nailable like hard natural wood. Their flexural strength decreased as temperature increased. By replacing 50% sawdust in weight by perlite, the composite exhibited less die swell and better performance in resisting high temperature.China Ministry of Science & Technology and the European Commission