Comparison of the Dynamic Behavior of Different Multipliers in the 8 × 8 Inverse Discrete Cosine Transform, using VHDL

The Inverse Discrete Cosine Transform (idct) is used in almost all video-decoders, like mpeg and hdtv. In de process of video decoding, the idct is a computationally heavy part. One of the performance characteristics is the power consumption, which is related to the dynamic behavior of the hardware. In this paper the signal transitions that occur in the multipliers are analyzed with vhdl, when two's complement arithmetic is changed in signed binary arithmetic. The simulations show that the signed binary multipliers need about three time less signal transitions than two's complement multipliers. I. Introduction The use of digital coded video signals (images) will increase in the near future. Digital signals are more robust and more flexible then the analogue representations. On the other hand digital video needs a lot of data (ca. 200 Mbit/sec). Therefore compression of the images, and the image-sequences is necessary. The current standard for coding digital image-sequences is mpeg, ..

Remote sensing of geomorphological and ecological change in response to saltmarsh managed realignment, The Wash, UK

An integrated remote sensing approach quantified saltmarsh dynamics in response to a sudden change in surface elevation due to a saltmarsh restoration scheme. The biogeomorphological relationship between surface elevation and saltmarsh presence occurs over the long-term so can be difficult to observe, though the ‘managed realignment’ of coastal defences provides a unique experimental opportunity to study this relationship. Realignment at Freiston Shore, Lincolnshire, UK in August 2002 caused a sudden and high-magnitude sediment input into the local coastal system, significantly increasing the intertidal surface elevation. The resulting impacts on the external, fronting saltmarsh were quantified by aerial photography and airborne multispectral imagery. Algal and pioneer saltmarsh boundary positions were calculated from 1984 to 2006, with the latter zone migrating slowly seaward pre-realignment (3.8 m a−1), but advancing significantly post-realignment (21.3 m a−1). Classification of five-year multispectral imagery accurately showed subtle changes in vegetation community composition within these boundaries. The realignment site was also colonized rapidly compared to other restoration sites, due to its high starting surface elevation. This study shows how, with sufficient sediment input and accommodation space, coastal management decisions can release intertidal surfaces from physical constraints to saltmarsh colonization