A separable two-dimensional discrete Hartley transform

Bracewell has proposed the Discrete Hartley Transform (DHT) as a substitute for the Discrete Fourier Transform (DFT), particularly as a means of convolution. Here, it is shown that the most natural extension of the DHT to two dimensions fails to be separate in the two dimensions, and is therefore inefficient. An alternative separable form is considered, corresponding convolution theorem is derived. That the DHT is unlikely to provide faster convolution than the DFT is also discussed

Sessile Invertebrate Colonization on Rocky Outcrops at Gray\u27s Reef National Marine Sanctuary

Documenting patterns of sessile invertebrate community development is important for predicting recovery patterns after disturbance and designing effective marine reserves. In the South Atlantic Bight, invertebrate assemblages can differ significantly from one rocky outcrop to another, but the factors driving these differences are not well understood. I tracked community development for fourteen months at four rocky outcrops at Gray’s Reef National Marine Sanctuary (GRNMS) to address the predictions that (i) developing sessile invertebrate communities in this system do not exhibit a predictable pattern of succession and (ii) recolonization patterns for small patches of open space that become available are influenced by the composition of the invertebrate community in the immediate vicinity. Community development was followed for 14 months on paving tiles (30 x 30 cm) deployed in July 2012 by photographing these tiles, along with the adjacent natural community, each month through September 2013. Species composition, percent cover, and diversity were determined each month. Sessile invertebrate taxa colonizing tiles were similar across all four sites in the first three months after deployment, but diverged over time. At all sites, developing communities exhibited lower percent cover and diversity than their adjacent existing communities over the fourteen months of the study, but analyses of similarities (ANOSIM) did provide evidence of convergence over the long term. These results indicate that succession of sessile invertebrates is not a predictable process in this system and that the extant community plays a role in deciding the final outcome of species re-establishment. Thus, differences in invertebrate community structure among rocky outcrops likely persist in this system because the extant community influences recruitment

Introduction : l'économie à l'œuvre

Il est doublement symptomatique que les études sur les interactions entre art et argent, entre économie et littérature, se soient multipliées au cours des vingt dernières années. Cette émergence d'un nouveau champ d'investigation scientifique témoigne à la fois de la richesse des matériaux que nous fournit la littérature pour articuler ce type de problématiques et des préoccupations de notre propre époque face au statut du discours économique et des comportements qu'il modélise. S'imposant aujourd'hui comme le modèle dominant de représentation du monde, à travers une colonisation progressive du langage, une reconfiguration de l'imaginaire et un remodelage des consciences auxquels n'échappe pas la littérature, malgré qu'elle en ait, l'économie a destin lié avec l'invention de la modernité depuis la seconde moitié du XVIIe siècle jusqu'à sa contestation de nos jours. Ce faisant, elle s'est imposée comme la matrice de l'ensemble de nos constructions culturelles et le marqueur de leur modernité. Georg Simmel est ainsi fondé à affirmer dans son Journal : "L'argent est la seule création culturelle qui soit de pure énergie, qui se soit complètement abstraite de son support matériel, n'étant plus qu'un absolu symbole. Il est le plus significatif des phénomènes de notre temps dans la mesure où sa dynamique a envahi le sens de toute théorie et de toute pratique". Or la plus grande force de ce discours économique largement hégémonique est de faire croire qu'il n'existe pas, autrement dit, de chercher à se naturaliser en se fondant dans les représentations socialement et idéologiquement dominantes qu'il nourrit et qui en retour contribuent à l'accréditer. En partie au moins complice de telles évolutions, même malgré elle, la littérature offre l'image ambivalente d'être un terrain de manoeuvre de telles évolutions, mais un terrain miné, qui permet, à travers leur expérimentation souvent fascinée, de fourbir par la bande les armes herméneutiques de leur possible déconstruction. L'objectif du présent volume, fruit de la mise en commun de compétences disciplinaires et d'approches diverses, inspirées par le sentiment d'un devoir d'inventaire, est de rendre sensible cet ambivalent pouvoir qu'a la littérature de relancer l'imaginaire économique pour le défléchir

Fast Single Shot Detection and Pose Estimation

For applications in navigation and robotics, estimating the 3D pose of objects is as important as detection. Many approaches to pose estimation rely on detecting or tracking parts or keypoints [11, 21]. In this paper we build on a recent state-of-the-art convolutional network for slidingwindow detection [10] to provide detection and rough pose estimation in a single shot, without intermediate stages of detecting parts or initial bounding boxes. While not the first system to treat pose estimation as a categorization problem, this is the first attempt to combine detection and pose estimation at the same level using a deep learning approach. The key to the architecture is a deep convolutional network where scores for the presence of an object category, the offset for its location, and the approximate pose are all estimated on a regular grid of locations in the image. The resulting system is as accurate as recent work on pose estimation (42.4% 8 View mAVP on Pascal 3D+ [21] ) and significantly faster (46 frames per second (FPS) on a TITAN X GPU). This approach to detection and rough pose estimation is fast and accurate enough to be widely applied as a pre-processing step for tasks including high-accuracy pose estimation, object tracking and localization, and vSLAM

Transmission and reflection of Gaussian beams by anisotropic parallel plates

Explicit and compact expressions describing the reflection and the transmission of a Gaussian beam by anisotropic parallel plates are given. Multiple reflections inside the plate are taken into account as well as arbitrary optical axis orientation and angle of incidence.Comment: 20 page

Assessing the differences between numerical methods and real experiments for the evaluation of reach envelopes of the human body

The use of static human body dimensions to assess the human accessibility is an essential part of an ergonomic approach in user-centered design. Assessments of reach capability are commonly performed by exercising external anthropometry of human body parts, which may be found in anthropometric databases, to numerically define the reach area of an intended user population. The result is a reach envelope determined entirely by the segment lengths, without taking into account external variables, as the nature of the task or the physical capacities of the subject, which may influence the results. Considering the body as a simple assembly of static parts of different anthropometry is limiting. In this paper, the limit of validity of this approach is assessed by comparing the reach envelopes obtained by this method to those obtained with a simple two-dimensional experimental reaching task of a panel of subjects. Forty subjects experimentally evaluated the reach, first with the body constrained and second unconstrained. Results were recorded and compared with those obtained numerically with a model, based on their own anthropometric characteristics, previously measured. A statistical study of the results allowed the definition of the shape of a confidence bound containing the real reach envelope. The results indicated important differences between the experiment and the numerical evaluation of the reach envelope.Comment: Colloque National AIP-Prim\'eca, Mar 201

A new approach for specifying and solving layout problems

International audienceComponent and facility layout plays an important role in the design and usability of many engineering products and systems as mechanical design, process plan, management and architecture including ship compartment layout. Generally, layout problems are formulated and solved on a case by case basis and, as far as we know, there is no general method to specify the similarities and characteristics of each problem. Then, this paper proposes an innovative generic approach in order to describe, formulate and solve layout problems. This approach suggests in particular a new classification of layout components, introducing the concept of "virtual" component. Moreover, in order to propose to the designer an optimal spatial arrangement in a reasonable time, this paper presents an interactive optimization strategy for solving layout problems

Avatars mémoriels et réalité historique augmentée : la Révolution française à travers ses produits dérivés

Dans un contexte marqué par l’instrumentalisation du « récit national » à des fins politiques et par l’essor d’une historiographie qui fait la part belle aux sensibilités, voire aux représentations fictionnalisées, la conscience historienne trouve dans une culture globalisée à l’ère numérique de nouvelles formes de médiation : elles sont issues aussi bien des cultures populaires que des postures artistiques ou de la production à vocation commerciale, qu’il s’agisse de consommation de masse ou d’industrie de luxe. Cet article définit les « avatars mémoriels », envisagés à partir de la production d’objets, d’images et d’imaginaires associés à la Révolution française dans la société contemporaine. Il met en évidence la contribution paradoxale de différents supports, qu’ils soient matériels ou immatériels, à la diffusion d’une certaine vision de l’histoire. Certes souvent naïve et fantasmée, elle est aussi, généralement, relativement bien informée. Parfois irrévérencieuse, voire subversive, elle exploite une connivence à rebours des effets d’inculcation et d’assignation du discours historique officiel. Les avatars mémoriels constituent par conséquent pour l’historiographie un champ d’observation privilégié de l’inconscient culturel façonné au gré des mythes et stéréotypes associés à l’histoire, inconscient qui innerve notre champ politique et médiatique.In a context marked by political manipulations of the ‘national narrative’ and by the rise of historiographical approaches giving prominence to sensibilities and even to fictional representations, historical consciousness finds new forms of mediation in the globalised culture of the digital age. These forms draw just as heavily on popular culture as they do on artistic stances or commercial production, whether the goods in question be luxury products or destined for mass consumption. This article defines ‘memorial avatars’ associated with the French Revolution in contemporary society by situating them in the production processes of objects, images and imaginaries. It shows the paradoxical contributions different media, both material and immaterial, make to the dissemination of a certain vision of history in society. Although often naïve and the object of fantasy, these visions of history are generally quite well-informed. They are sometimes irreverent or even subversive and play on shared understandings that go against the grain of official history’s discourse which assigns things to their rightful places and imposes interpretations. Memorial avatars provide the historiographer with a privileged perspective on the cultural unconscious which is shaped by myths and stereotypes associated with history and which structures our political and media spheres