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Abstract: The ridge gap waveguide is a new transmission line for millimeter-wave applications. Traditionally, rectangular waveguides are used for those applications due to their low loss. However their fabrication requires precision machining, very good electrical contact and alignment between two joining mechanical parts. Ridge gap waveguides can obtain similar performance without requiring conductive sidewalls and this provides more freedom during the fabrication and assembly process as the structure is no longer sensitive to small gaps between the side walls and the upper lid. The ridge gap waveguide has already been validated for 10-20GHz using conventional fabrication methods. The ridge gap waveguide prototypes presented in this paper are designed to work in the frequency region between 210 and 340GHz, and fabricated using MEMS technology. MEMS technology provides fabrication precision of the structures and thus opens the path for high-frequency components. [Copyright &y& Elsevier]

Due to the dynamic inter-relationship between human society and water resources, decision-making is a tricky task in water management sectors. In this study, multi-criteria analysis has been used as a decision support tool for the selection of a sustainable option in a regional channel improvement in Bangladesh. The Malnichara channel flows across the north-eastern divisional city of the country, and is responsible for storm water conveyance to the downstream Surma River. The channel was observed to be at risk due to anthropogenic activities such as encroachment, sewage and solid waste disposal and the filling up of natural depression basins. Using the multi-criteria analysis, three alternatives for channel improvement (sodding natural channel, lined natural channel and concrete box culvert) were evaluated with respect to ten indicators, grouped into four sustainability criteria (technical, economic, environmental and social). Sodding natural channel was found to be the optimal alternative, though the selection was sensitive to social criteria. Such a straightforward tool can efficiently be used to ensure sustainability of the channel through stakeholders' involvement in decision-making. [ABSTRACT FROM AUTHOR]