1,634 research outputs found
Linear Collider Collaboration Tech Notes Improved Overhead Accounting in the NLC Main Linac Improved Overhead Accounting in the NLC Main Linacs
No full textAbstract This note documents a set of expressions used to explore the issue of whether or not it is reasonable to consider a conventional positron source for a Tesla formatted beam. The critical issue is that of energy deposition in the conversion target and the comparison of the induced stress with the ultimate tensile strength of the target material. Since the length of the incident beam pulse is large in comparison to the ratio of beam size to the speed of sound, the concurrent pressure pulse dissipates in a time short compared to the overall pulse duration and one is left with only the Improved Overhead Accounting in the NLC Main Linac Peter Tenenbaum June Improved Overhead Accounting in the NLC Main Linacs P. Tenenbaum LCC-Note-0148 June 9, 2004 Abstract The NLC main linac contains 1,116 RF power units, of which 5% are considered "spares" for replacement of failed power units, make-up of the energy gain during an RF breakdown, and energy feedback. A more careful accounting for the effects of beam loading indicates that the NLC can operate with less BNS overhead and a smaller mean phase offset than was originally specified, and that as a consequence the total number of spares is actually about 7.9% of the total
L'Art décoratif en Europe du néo classicisme à l'art déco. Sous la direction d'A. Gruber, avec la collaboration de P. Arizzoli-Clémentel, N. Blondel, J. du Pasquier, B. Blench, D. Klein, R. Fohr. Paris, Citadelles et Mazenod, t. III, 1994. 495 p., nb. ill. en n. et bl. et en coul.
No full textDion-Tenenbaum Anne. L'Art décoratif en Europe du néo classicisme à l'art déco. Sous la direction d'A. Gruber, avec la collaboration de P. Arizzoli-Clémentel, N. Blondel, J. du Pasquier, B. Blench, D. Klein, R. Fohr. Paris, Citadelles et Mazenod, t. III, 1994. 495 p., nb. ill. en n. et bl. et en coul.. In: Revue de l'Art, 1995, n°109. pp. 83-84
Compte rendu de Gérald Tenenbaum : «Des mots & des maths»
No full textTenenbaum (Gérald), Des mots & des maths. – Paris : Odile Jacob, 2019. – 216 p. – 1 vol. broché de 14,5 × 22 cm. – 21,90 €. – isbn 978-2-7381-4900-8
Locality Sensitive Hashing for Set-Queries, Motivated by Group Recommendations
No full textLocality Sensitive Hashing (LSH) is an effective method to index a set of points such that we can efficiently find the nearest neighbors of a query point. We extend this method to our novel Set-query LSH (SLSH), such that it can find the nearest neighbors of a set of points, given as a query.
Let s(x,y) be the similarity between two points x and y. We define a similarity between a set Q and a point x by aggregating the similarities s(p,x) for all p∈ Q. For example, we can take s(p,x) to be the angular similarity between p and x (i.e., 1-(∠(x,p)/π)), and aggregate by arithmetic or geometric averaging, or taking the lowest similarity.
We develop locality sensitive hash families and data structures for a large set of such arithmetic and geometric averaging similarities, and analyze their collision probabilities. We also establish an analogous framework and hash families for distance functions. Specifically, we give a structure for the euclidean distance aggregated by either averaging or taking the maximum.
We leverage SLSH to solve a geometric extension of the approximate near neighbors problem. In this version, we consider a metric for which the unit ball is an ellipsoid and its orientation is specified with the query.
An important application that motivates our work is group recommendation systems. Such a system embeds movies and users in the same feature space, and the task of recommending a movie for a group to watch together, translates to a set-query Q using an appropriate similarity
On the Impact of Multipath Interference Noise in All-Raman Dispersion-Compensated Links
No full textJournal Pape
Three studies on sums of multiplicative functions over friable integers
No full textCe travail est consacré à l'étude de trois problèmes liés à l'évaluation de sommes de fonctions multiplicatives sur les entiers friables. On dit qu'un nombre entier n est y-friable si son plus grand facteur premier P(n) n'excède pas y. Dans une première partie, nous considérons une fonction multiplicative aléatoire au sens de Wintner, c'est-à-dire une fonction arithmétique multiplicative f supportée par les entiers sans facteur carré, telle que, pour tout entier premier p, f(p) est une variable aléatoire de Bernoulli prenant les valeurs +1 et -1 avec probabilité 1/2. Dans la continuité de travaux de Wintner, Erdös, Halasz, Lau, Tenenbaum et Wu, notre étude est dédiée à l'obtention d'une majoration presque sûre de la fonction sommatoire de f sur les entiers y-friables n'excédant pas x. Un second volet est dévolu à l'évaluation asymptotique des fonctions sommatoires de certaines fonctions multiplicatives, notamment la fonction phi d'Euler, sur les translatés des entiers friables. La méthode employée fait appel à des résultats de répartition des entiers friables dans les progressions arithmétiques. La troisième partie consiste en une étude de la loi moyenne de répartition des diviseurs des entiers friables. Nous établissons le glissement, lorsque le paramètre de friabilité u = (log x)/log y croît, depuis la loi de l'arcsinus (établie en 1979 dans les travaux de Dress, Deshouillers et Tenenbaum) jusqu'à une loi approximativement gaussienne. La loi limite obtenue s'exprime au moyen d'une convolution faisant apparaître les fonctions de DickmanThis dissertation is devoted to studying three problems, all linked to estimates for sums of multiplicative functions over friable integers. An integer n is called y-friable if its largest prime factor P(n) does not exceed y. In a first part, we consider a random multiplicative function in the sense of Wintner, i.e. a multiplicative arithmetic function f supported on squarefree integers and such that, for each prime p, f(p) is a Bernoulli random variable taking each value +1 and -1 with probability 1/2. Elaborating on previous works by Wintner, Erdös, Halasz, Lau, Tenenbaum and Wu, we investigate upper bounds for the summatory function of f over y-friable integers not exceeding x. In the second part, we provide asymptotic estimates for sums of certain multiplicative functions, including Euler's totient, over shifted friable integers. This study depends on the distribution of friable integers in arithmetic progressions. In the third part, we consider a friable extension of the Arcsine law for the mean distribution of the divisors of integers. The original study is due to Deshouillers, Dress and Tenenbaum (1979). We describe the limit law in terms of the Dickman functions and we show that, as the friability parameter u = (log x)/log y increases, the mean distribution drifts from the Arcsine law towards a Gaussian behaviou
Locality Sensitive Hashing for Efficient Similar Polygon Retrieval
No full textLocality Sensitive Hashing (LSH) is an effective method of indexing a set of items to support efficient nearest neighbors queries in high-dimensional spaces. The basic idea of LSH is that similar items should produce hash collisions with higher probability than dissimilar items.
We study LSH for (not necessarily convex) polygons, and use it to give efficient data structures for similar shape retrieval. Arkin et al. [Arkin et al., 1991] represent polygons by their "turning function" - a function which follows the angle between the polygon’s tangent and the x-axis while traversing the perimeter of the polygon. They define the distance between polygons to be variations of the L_p (for p = 1,2) distance between their turning functions. This metric is invariant under translation, rotation and scaling (and the selection of the initial point on the perimeter) and therefore models well the intuitive notion of shape resemblance.
We develop and analyze LSH near neighbor data structures for several variations of the L_p distance for functions (for p = 1,2). By applying our schemes to the turning functions of a collection of polygons we obtain efficient near neighbor LSH-based structures for polygons. To tune our structures to turning functions of polygons, we prove some new properties of these turning functions that may be of independent interest.
As part of our analysis, we address the following problem which is of independent interest. Find the vertical translation of a function f that is closest in L₁ distance to a function g. We prove tight bounds on the approximation guarantee obtained by the translation which is equal to the difference between the averages of g and f
Brian McGuinness, Wittgenstein. 1. Les années de jeunesse 1889-1921. Biographie. Traduit de l'anglais par Yvonne Tenenbaum
No full textPourtois Hervé. Brian McGuinness, Wittgenstein. 1. Les années de jeunesse 1889-1921. Biographie. Traduit de l'anglais par Yvonne Tenenbaum. In: Revue Philosophique de Louvain. Quatrième série, tome 91, n°92, 1993. p. 680
Physical reasoning in complex scenes is sensitive to mass
No full text<p>Hamrick, J. B., Battaglia, P. W., & Tenenbaum, J. B. (2012, May). Physical reasoning in complex scenes is sensitive to mass. Poster presented at the Annual Meeting of the Vision Sciences Society. Naples, FL.</p
Extra-arachnoidal cranio-cervical decompression for syringomyelia associated with Chiari I malformation in adults: technique assessment
No full textThe osteo-dural decompression of the cerebellar tonsils at the cranio-cervical junction is generally considered the most effective treatment for syringomyelia-Chiari I complex. However much controversy concerning a great number of surgical adjuvants to the standard bony decompression is still present. In this work an extra-arachnoidal cranio-cervical decompression (CCD) without duroplasty is described and the surgical results are reported
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