Conservative Signal Processing Architectures For Asynchronous, Distributed Optimization Part II: Example Systems

This paper provides examples of various synchronous and asynchronous signal processing systems for performing optimization, utilizing the framework and elements developed in a preceding paper. The general strategy in that paper was to perform a linear transformation of stationarity conditions applicable to a class of convex and nonconvex optimization problems, resulting in algorithms that operate on a linear superposition of the associated primal and dual decision variables. The examples in this paper address various specific optimization problems including the LASSO problem, minimax-optimal filter design, the decentralized training of a support vector machine classifier, and sparse filter design for acoustic equalization. Where appropriate, multiple algorithms for solving the same optimization problem are presented, illustrating the use of the underlying framework in designing a variety of distinct classes of algorithms. The examples are accompanied by numerical simulation and a discussion of convergence

Unveiling The Tree: A Convex Framework for Sparse Problems

This paper presents a general framework for generating greedy algorithms for solving convex constraint satisfaction problems for sparse solutions by mapping the satisfaction problem into one of graph traversal on a rooted tree of unknown topology. For every pre-walk of the tree an initial set of generally dense feasible solutions is processed in such a way that the sparsity of each solution increases with each generation unveiled. The specific computation performed at any particular child node is shown to correspond to an embedding of a polytope into the polytope received from that nodes parent. Several issues related to pre-walk order selection, computational complexity and tractability, and the use of heuristic and/or side information is discussed. An example of a single-path, depth-first algorithm on a tree with randomized vertex reduction and a run-time path selection algorithm is presented in the context of sparse lowpass filter design

Reproduction and adaptation characteristics in D’man sheep

D’man breed (D) is found in the oasis of the subsaharian regions of Morocco and reared usually in sedentary type of management with small flocks (< 10 ewes). Preliminary field surveys showed that D is early maturing, prolific and aseasonal. Hence, a multidisciplinary research programme on D was started in 1974. This paper reports the findings of these studies and describes the approach used to (1) characterize and evaluate the performances of D in field and station, (2) study the physiological mechanism involved in its peculiar reproduction and production, (3) study the genetic basis of reproduction parameters, and (4) evaluate use of D in crossbreeding schemes to improve the productivity of other Moroccoan breeds. Results show that D is one of the rare breeds that is simultaneously early maturing, highly prolific and completely aseasonal. However, studies on water turnover and nitrogen recycling show that D is not well adapted to hot climate and poor nutrition. Its reproduction parameters are relatively independent of photoperiod and related to a low sensitivity to negative oestrogen feedback. D male is characterized by high libido and can be used for synchronizing oestruses through the »ram effect». Crossbreeding experiments with non-prolific sheep confirm the heritability of reproductive parameters. However, the genetic basis for these is not yet well known

Flowering and pollination time affect fruit set of foreign almond cultivars in Morocco

The associations ‘Marcona’-‘Fournat de Brézenaud’ and ‘Ferragnès’-‘Ferraduel’ are the cultivar combinations mostly planted in commercial almond orchards in Morocco. The blooming times and effective pollination period (EPP) were determined for these associations to determine the effect of blooming and pollination times on the irregular yields observed in Morocco with these cultivars. ‘Marcona’ bloom was earlier than that of ‘Fournat de Brézenaud’, but ‘Ferragnès and ‘Ferraduel’ coincided. Fruit set and percentage of pistils with pollen grains was maximized when pollination occurred at day 2 after emasculation. Fruit set and stigmatic receptivity decreased drastically by day 4 after emasculation. Fruit set in the open pollination treatment was lower than that obtained after hand pollination at days 0 and 2 after emasculation, especially in ‘Marcona’. These results emphasize the importance of early pollination and the selection of new cultivars with the same flowering period as ‘Marcona’ to improve almond yields in Morocco.Peer ReviewedPrunus amygdalusbloomeffective pollination periodstigmatic receptivityfruit setPublishe

In memoriam: Serge Moscovici (1925-2014)

International audiencePreface by the EASP Executive Committee and the Chief Editors of EJS