Abstract
Sequences of loops or sets of nested loops exist in many applications. This paper shows a scheme to pipeline those sequences of loops in such a way that subsequent loops can start execution before the end of the previous ones. It uses a hardware scheme with decoupled and concurrent datapath and control units that start execution at the same time. The communication of data items between two loops in sequence is conducted by memories. Each element of one of such memories is responsible to flag the availability of the data requested by a subsequence loop. Thus, the control execution of subsequent loops is also orchestrated by data availability and out-of-order produced-consumed pairs are permitted. We apply the concept to a real example: a fast DCT algorithm.

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Abstract
Spatial and temporal sea level variability in the North Atlantic is investigated from Topex/Poseidon (T/P) altimetry data. Time series of sea level anomalies on a regular 5 degrees grid are analysed. Non-linear denoising through thresholding in the wavelet transform domain is carried out for each series in order to remove noise while preserving non-smooth features. Principal Component Analysis (PCA) is used to obtain a spatio-temporal description of the sea level field, To avoid modal mixing and improve interpretation of the principal modes, PCA is implemented separately for seasonal and trend components of the sea level field obtained from a wavelet-based multiresolution analysis. The leading pattern of the seasonal field reflects the dominance of a stable annual cycle over the study area and the change in the seasonal regime approaching the equator with contribution of the semi-annual cycle and phase-shift in the annual cycle in the tropical Atlantic. The leading pattern of the trend field is a broad spatial pattern associated with North Atlantic Oscillation (NAO), reflecting the influence of atmospheric conditions on interannual sea level variability.