Optical Flow Requires Multiple Strategies (but only one network)

We show that the matching problem that underlies optical flow requires multiple strategies, depending on the amount of image motion and other factors. We then study the implications of this observation on training a deep neural network for representing image patches in the context of descriptor based optical flow. We propose a metric learning method, which selects suitable negative samples based on the nature of the true match. This type of training produces a network that displays multiple strategies depending on the input and leads to state of the art results on the KITTI 2012 and KITTI 2015 optical flow benchmarks

Ancient Urban Ecology Reconstructed from Archaeozoological Remains of Small Mammals in the Near East

Acknowledgments We especially thank the many archaeologists who collaborated closely with our project and invested pioneering efforts in intensive fine-scale retrieval of the archaeozoological samples that provided the basis for this study: Shai Bar, Amnon Ben-Tor, Amit Dagan, Yosef Garfinkel, Ayelet Gilboa, Zvi Greenhut, Amihai Mazar, Stefan Munger, Ronny Reich, Itzhaq Shai, Ilan Sharon, Joe Uziel, Sharon Zuckerman, and additional key excavation personnel who were instrumental in collection of the samples or in assisting the work including: Shimrit Bechar, Jacob Dunn, Norma Franklin, Egon Lass and Yiftah Shalev. Funding:The research was funded by a post-doctoral grant awarded to L.W. from the European Research Council under the European Community’s Seventh Framework Program (FP7/2007e2013)/ERC grant agreement number 229418. The laboratory work was also supported by funding by the Israel Science Foundation (Grant 52/10). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.Peer reviewedPublisher PD

Entangled single-wire NiTi material: a porous metal with tunable superelastic and shape memory properties

NiTi porous materials with unprecedented superelasticity and shape memory were manufactured by self-entangling, compacting and heat treating NiTi wires. The versatile processing route used here allows to produce entanglements of either superelastic or ferroelastic wires with tunable mesostructures. Three dimensional (3D) X-ray microtomography shows that the entanglement mesostructure is homogeneous and isotropic. The thermomechanical compressive behavior of the entanglements was studied using optical measurements of the local strain field. At all relative densities investigated here ($\sim$ 25 - 40$\%$), entanglements with superelastic wires exhibit remarkable macroscale superelasticity, even after compressions up to 25$\%$, large damping capacity, discrete memory effect and weak strain-rate and temperature dependencies. Entanglements with ferroelastic wires resemble standard elastoplastic fibrous systems with pronounced residual strain after unloading. However, a full recovery is obtained by heating the samples, demonstrating a large shape memory effect at least up to 16% strain.Comment: 31 pages, 10 figures, submitted to Acta Materiali

Mécanique des milieux fibreux auto-enchevêtrés : application à un alliage à mémoire de forme de type Nickel-Titane

The aim of this work is to process and characterize for biomedical applications,self-entangled structures made of a single NiTi shape memory fiber. We have optimizeda processing route consisting in entangling and shape-setting a spring bythermomechanical treatments. The samples were characterized in compression andtension, using optical and x-ray tomographic observations. The structures thus obtainedare homogeneous, isotropic, superelastic at room temperature up to strains ofat least 30%, and can become ferroelastic with a shape memory effect up to at least16% strain by an additional heat treatment. The mechanical behavior in compressionis first consolidating and then dilating, while in tension, the samples are slightlyauxetic. A comparison with similar media made of ductile and viscoelastic fibers,as well as with discrete element simulations on friction-free elastic fibers, show thatthe mechanical properties of these self-entangled structures are controlled by theirunique architecture, in-between continuous and discrete media.L’objectif de ce travail est d’élaborer et de caractériser pour des applications biomédicalesun matériau auto-enchevêtré à base d’une seule fibre d’alliage à mémoire deforme de type Nickel-Titane. Nous avons optimisé un procédé de fabrication consistantà enchevêtrer et figer un ressort par des traitements thermiques. Les échantillonsont été caractérisés en compression et traction, avec suivi par caméra optique ettomographie in-situ. Les structures obtenues sont homogènes, isotropes, superélastiquesà température ambiante jusqu’à des déformations d’au moins 30%, et peuventdevenir ferroélastiques avec un effet mémoire d’au moins 16% par un traitement thermiqueadditionnel. Leur comportement en compression est consolidant puis dilatantet en traction, légèrement auxétique. Une comparaison avec des milieux similairesconstitués de fils ductiles et viscoélastiques, ainsi qu’avec des simulations par élémentsdiscrets sur des milieux élastiques sans frottement, montre que les propriétésmécaniques des structures auto-enchevêtrées sont contrôlées par leur architecturesingulière, à mi-chemin entre milieux continus et discrets

Causes of (and Solutions for?) Financial Crises in Local Governments: Insights From Local Arab Authorities in Israel

This is an Accepted Manuscript of an article published by SAGE Publications in Administration and Society on November 21, 2014, available at: https://doi.org/10.1177/0095399714556501.This article examines the relative impact of internal and external factors on the financial decline of local Arab municipalities in Israel. We employ a unique case study to demonstrate that the negative relationship between local management policies and local financial crises is stronger than any other relationship; in addition, this relationship is expected to hold for other local authorities in Israel and for local authorities in Western countries. The new theoretical approach developed in this study indicates that, with respect to local authorities, the “local management approach” more often explains a financial crisis than other approaches

Antidoping régulations in horses

Equestrian sports are subject to the same antidoping legislation as human competitions, which, in France, fall under the authority of the Ministry of Youth and Sports. Racing however, is governed by a regulatory body, which is itself controlled by the Ministry of Agriculture. Interestingly, compared to antidoping control in human competitions, the system used in equestrian sports is very strict, whether in racing or other equestrian sports. This is due partly to the financial means provided by the betting industry, but more importantly to the sport’s chosen ethics. However, there are some differences between antidoping control in racing or in other equestrian sports.La lutte contre le dopage du cheval dans les sports équestres est régie par la même loi que celle traitant du dopage dans les compétitions sportives humaines. Cette loi réserve au ministère de tutelle, le ministère de la jeunesse et des sports, un rôle principal. A contrario, les courses sont régies par un règlement (code des courses) approuvé par le ministère de tutelle qui est le ministère de l'agriculture. Comparé à ce qui est mis en place pour lutter contre le dopage dans les compétitions sportives humaines, le dispositif construit pour les compétitions de chevaux, qu'elles soient équestres ou hippiques, est un système performant. Sa force réside dans les moyens que les enjeux des courses autorisent et surtout, dans les valeurs auxquelles adhèrent les filières et dans les politiques qui en découlent. On discernera néanmoins des différences entre le dispositif des courses et celui des sports équestres

Aperiodic nano-photonic design

The photon scattering properties of aperiodic nano-scale dielectric structures can be tailored to closely match a desired response by using adaptive algorithms for device design. We show that broken symmetry of aperiodic designs provides access to device functions not available to conventional periodic photonic crystal structures.Comment: 23 pages, LaTex, 8 postscript figure

Robust Reinforcement Learning via Adversarial Kernel Approximation

Robust Markov Decision Processes (RMDPs) provide a framework for sequential decision-making that is robust to perturbations on the transition kernel. However, robust reinforcement learning (RL) approaches in RMDPs do not scale well to realistic online settings with high-dimensional domains. By characterizing the adversarial kernel in RMDPs, we propose a novel approach for online robust RL that approximates the adversarial kernel and uses a standard (non-robust) RL algorithm to learn a robust policy. Notably, our approach can be applied on top of any underlying RL algorithm, enabling easy scaling to high-dimensional domains. Experiments in classic control tasks, MinAtar and DeepMind Control Suite demonstrate the effectiveness and the applicability of our method