A recursively feasible and convergent Sequential Convex Programming procedure to solve non-convex problems with linear equality constraints

A computationally efficient method to solve non-convex programming problems with linear equality constraints is presented. The proposed method is based on a recursively feasible and descending sequential convex programming procedure proven to converge to a locally optimal solution. Assuming that the first convex problem in the sequence is feasible, these properties are obtained by convexifying the non-convex cost and inequality constraints with inner-convex approximations. Additionally, a computationally efficient method is introduced to obtain inner-convex approximations based on Taylor series expansions. These Taylor-based inner-convex approximations provide the overall algorithm with a quadratic rate of convergence. The proposed method is capable of solving problems of practical interest in real-time. This is illustrated with a numerical simulation of an aerial vehicle trajectory optimization problem on commercial-of-the-shelf embedded computers

Crier la Libération en France (1944-1945)

A partir des slogans, chants et cris prononcé lors de la libération de la France en 1944 cet article analyse l'univers sonore de cet événement

Lyell and the Spanish Geology

Lyell visited Spain in the summer of 1830, after the publication of the first volume of Principles of Geology, and in the winter of 1853 coming back from his third trip to America. In his first stay he visited, among others, the Olot region (Catalonia, NE Spain) and in the second the Canary Islands. In both cases his major aim was to study these volcanic zones since volcanism constituted for Lyell the clearest evidence of the Earth interior energy, which had led to mountain building in the past. Another of his aims during his 1830 visit was to study the Pyrenees. Lyell endeavoured to show that this orogen did not result from a violent and rapid revolution, as proposed by Elie de Beaumont, but from processes that spanned long time periods. In the Pyrenees he also made some observations on the neogene lacustrine deposits of la Cerdanya basin, while in the southern Pyrenean foreland (i.e. Ebro basin) he paid attention to facies changes and correlations in the Eocene sequences. Lyell spent some days in Barcelona during this visit but at that time the country was in political turmoil and the main scientific institutions of the city had been closed down. Once in the Olot region, Lyell paid a visit to Bolós, pharmacist and botanist who had an interest in geology and introduced him in the volcanic zone. During his second trip in 1853, Lyell visited the Canaries and limited his personal contacts to Pedro Maffiote, professor of the Nautical School of Tenerife, who had made some interesting although never published geological observations in this island. In the Canary Islands Lyell sought to demonstrate the relationship between volcanism and coastal movement, and to confirm his theory of volcanic cone growth by accretion. Lyell's influence in Spain was not due to his personal contacts in the country but to his books and especially the translation into Spanish by Ezquerra del Bayo of the first edition of "Elements of Geology" in 1838. Lyell's ideas and especially his geological terminology, which was one of his most important contributions, spread in Spain thanks to this translation. Both the personality and the scientific reputation of Ezquerra del Bayo helped to promote the book that became for many years the official teaching book at the Schools of Mines in Spain and Mexico. Ezquerra del Bayo carried out the first geological map of the whole of Spain (1850) adopting in this and other publications (1850-1857) Lyell's nomenclature, although his theoretical concepts (e.g. actualism) did not exert the same influence. It should be borne in mind that Lyell regarded his Elements of Geology as a descriptive Geology, a text book for students and beginners. His more elaborated theories included in Principles of Geology resulted in little influence in Spain, since this book was not translated into Spanish

Des sites sans visiteurs : les mémoriaux du camp de Salaspils et de la forêt de Bikernieki en Lettonie

International audienceCeux qui se rendent aujourd'hui à Auschwitz, au-delà de ce qu'ils peuvent ressentir ou apprendre, constatent aussi qu'ils sont loin d'être les seuls à visiter ce symbole de l'extermination nazie. L'évolution du nombre de visiteurs confirme le caractère exceptionnel pris par ce site. En dix ans le nombre de visites annuelles est passé de 500 000 à 1 300 000. Dans le même temps, d'autres lieux connus de l'univers concentrationnaire ont vu leur fréquentation stagner, tout en demeurant au-dessus de plusieurs dizaines de milliers de visiteurs (jusqu'à 400 000 pour Sachsenhausen au nord de Berlin). À l'inverse, d'autres sites se visitent seuls ou presque, à l'image de deux mémoriaux proches de Riga en Lettonie, le mémorial de Salaspils et celui de la forêt de Bikernieki