Design principles for pressure moderated window frames

High performance window frames that are widely used in Europe rely on pressure moderation to achieve a good weathertightness. By separating the airtightness plane from the water shedding surface a drained cavity can be pressure moderated. As wind pressure is the main driving force for water to infiltrate into the frame, a pressure equalized system is able to achieve higher performance levels. In this paper the performance of window frames is analyzed in two separate ways: first of all experimental research was conducted on a single frame to analyze the way it functions and fails, secondly a database of the university window testing facility was used to perform a parametric analysis. High frequency measurements on window frames provide for the information to model the pressure in the cavity and render information on prevalent parameters. The influence of different elements (section, joggles, gaskets, fittings) is examined in both dry as well as rainy conditions during static and dynamic pressure differences. The airtightness of the outer plane divided by the airtightness of the inner plane is the main parameter that will determine the watertightness potential of window frames. Based on the research carried out within the framework of that program and the analysis of the test reports in the database design principles have been determined requisite to achieve adequate pressure moderation in window frames

Distributed Space-Time Coding Based on Adjustable Code Matrices for Cooperative MIMO Relaying Systems

An adaptive distributed space-time coding (DSTC) scheme is proposed for two-hop cooperative MIMO networks. Linear minimum mean square error (MMSE) receive filters and adjustable code matrices are considered subject to a power constraint with an amplify-and-forward (AF) cooperation strategy. In the proposed adaptive DSTC scheme, an adjustable code matrix obtained by a feedback channel is employed to transform the space-time coded matrix at the relay node. The effects of the limited feedback and the feedback errors are assessed. Linear MMSE expressions are devised to compute the parameters of the adjustable code matrix and the linear receive filters. Stochastic gradient (SG) and least-squares (LS) algorithms are also developed with reduced computational complexity. An upper bound on the pairwise error probability analysis is derived and indicates the advantage of employing the adjustable code matrices at the relay nodes. An alternative optimization algorithm for the adaptive DSTC scheme is also derived in order to eliminate the need for the feedback. The algorithm provides a fully distributed scheme for the adaptive DSTC at the relay node based on the minimization of the error probability. Simulation results show that the proposed algorithms obtain significant performance gains as compared to existing DSTC schemes.Comment: 6 figure