Feature Projection for Optimal Transport

Optimal transport is now a standard tool for solving many problems in statistics and machine learning. The optimal "transport of probability measures" is also a recurring theme in stochastic control and distributed control, where in the latter application the probability measure corresponds to an empirical distribution associated with a large collection of distributed agents, subject to local and global control. The goal of this paper is to make precise these connections, which inspires new relaxations of optimal transport for application in new and traditional domains. The proposed relaxation replaces a target measure with a "moment class": a set of probability measures defined by generalized moment constraints. This is motivated by applications to control, outlier detection, and to address computational complexity. The main conclusions are (i) A characterization of the solution is obtained, similar to Kantorovich duality, in which one of the dual functions in the classical theory is replaced by a linear combination of the features defining the generalized moments. Hence the dimension of the optimization problem coincides with the number of constraints, even with an uncountable state space; (ii) By introducing regularization in the form of relative entropy, the solution can be interpreted as replacing a maximum with a softmax in the dual; (iii) In applications such as control for which it is not known a-priori if the moment class is non-empty, a relaxation is proposed whose solution admits a similar characterization; (iv) The gradient of the dual function can be expressed in terms of the expectation of the features under a tilted probability measure, which motivates Monte-Carlo techniques for computation

Multi-Size-Mesh, Multi-Time-Step Algorithm for Noise Computation on Curvilinear Meshes

International audienceAeroacoustic problems are often multi-scale and a zonal refinement technique is thus desirable to reduce computational effort while preserving low dissipation and low dispersion errors from the numerical scheme. For that purpose, the multi-size-mesh multi-time-step algorithm of Tam and Kurbatskii [AIAA Journal, 2000, 38(8), p. 1331-1339] allows changes by a factor of two between adjacent blocks, accompanied by a doubling in the time step. This local time stepping avoids wasting calculation time, which would result from imposing a unique time step dictated by the smallest grid size for explicit time marching. In the present study, the multi-size-mesh multi-time-step method is extended to general curvilinear grids by using a suitable coordinate transformation and by performing the necessary interpolations directly in the physical space due to multidimensional interpolations combining order constraints and optimization in the wave number space. A particular attention is paid to the properties of the Adams-Bashforth schemes used for time marching. The optimization of the coefficients by minimizing an error in the wave number space rather than satisfying a formal order is shown to be inefficient for Adams-Bashforth schemes. The accuracy of the extended multi-size-mesh multi-time-step algorithm is first demonstrated for acoustic propagation on a sinusoidal grid and for a computation of laminar trailing edge noise. In the latter test-case, the mesh doubling is close to the airfoil and the vortical structures are crossing the doubling interface without affecting the quality of the radiated field. The applicability of the algorithm in three dimensions is eventually demonstrated by computing tonal noise from a moderate Reynolds number flow over an airfoil

Ordonnancement, assignation et transformations dynamiques de graphe simultanés pour projeter efficacement des applications sur CGRAs

National audiencePorter une application sur une architecture reconfigurable à gros grain est une tâche complexe qui reste encore souvent réalisée entièrement ou partiellement manuellement. Cet article présente un flot original de synthèse automatisé basé sur des étapes d'ordonnancement et d'assignation simultanées. L'approche proposée parcourt en sens inverse les noeuds du modèle formel extrait à partir du code de l'application compilé pour le transformer dynamiquement uniquement si nécessaire. Les résultats des expériences montrent que l'approche proposée permet une meilleure exploration de l'espace de solution et obtient la meilleure latence dans 90% des cas

Bernardin Frankapan i Krbavska bitka: je li spasio sebe i malobrojne ili je pobjegao iz boja?

Veliki poraz hrvatske vojske od Osmanlija na Krbavskom polju 9. rujna 1493. predstavlja jednu od najvažnijih epizoda u dugotrajnom obrambenom ratu Hrvata protiv Osmanlija. Iako su uzroci i posljedice, pa i sam tijek bitke, već u znatnoj mjeri prikazani u starijoj i novijoj hrvatskoj historiografiji, ipak su uloga i djelovanje kneza Bernardina Frankapana u samoj bitki i događajima koji su joj prethodili, ostali u značajnoj mjeri nerasvijetljeni i nerazjašnjeni. Autor na osnovi sačuvanih pisanih i arheoloških svjedočanstva, kao i nakon uvida na terenu, analizira događaje koji su prethodili Bernardinovu povlačenju iz bitke, pokušavajući odgonetnuti uzroke i motive takova poteza. Isto tako, detaljnijim uvidom u sačuvana pisana svjedočanstva o događajima prije Krbavske bitke, pokušava objasniti odnose između bana Derenčina i knezova Frankapana.The great defeat of Croatian army against ottoman troops in the battle of Krbava field (9th September 1493) is one of the most important episode in long–lasting defensive war against Ottoman Empire. Although, the causes and the consequences, and the very duration of the battle, are already elaborated in older and newer Croatian historiography, the role and actions of the duke Bernardin Frankapan in the events before battle and in the battle are still not illuminated and dismissed. Analyzing the written sources and archeological artifacts, author describes events that are preceded Bernardin’s evacuation from the battle. He is, also, trying to figure out the motives and causes of such actions. Further more, by detailing analysis of written sources about events before battle of Krbava field, author clarifies relationships between banus Derenčin and ducal family of Frankapan

Key Parameters Requirements for Non‐Fullerene‐Based Organic Solar Cells with Power Conversion Efficiency >20%

The reported power conversion efficiencies (PCEs) of nonfullerene acceptor (NFA) based organic photovoltaics (OPVs) now exceed 14% and 17% for single‐junction and two‐terminal tandem cells, respectively. However, increasing the PCE further requires an improved understanding of the factors limiting the device efficiency. Here, the efficiency limits of single‐junction and two‐terminal tandem NFA‐based OPV cells are examined with the aid of a numerical device simulator that takes into account the optical properties of the active material(s), charge recombination effects, and the hole and electron mobilities in the active layer of the device. The simulations reveal that single‐junction NFA OPVs can potentially reach PCE values in excess of 18% with mobility values readily achievable in existing material systems. Furthermore, it is found that balanced electron and hole mobilities of >10−3 cm2 V−1 s−1 in combination with low nongeminate recombination rate constants of 10−12 cm3 s−1 could lead to PCE values in excess of 20% and 25% for single‐junction and two‐terminal tandem OPV cells, respectively. This analysis provides the first tangible description of the practical performance targets and useful design rules for single‐junction and tandem OPVs based on NFA materials, emphasizing the need for developing new material systems that combine these desired characteristics

Application of multi-objective optimization techniques for improved emissions and fuel economy over transient manoeuvres

This paper presents a novel approach to augment existing engine calibrations to deliver improved engine performance during a transient through the application of multi-objective optimization techniques to the calibration of the Variable Valve Timing (VVT) system of a 1.0 litre gasoline engine. Current mature calibration approaches for the VVT system are predominantly based on steady state techniques which fail to consider the engine dynamic behaviour in real world driving, which is heavily transient. In this study the total integrated fuel consumption and engine out NOx emissions over a 2min segment of the transient Worldwide Light-duty Test Cycle are minimised in a constrained multi-objective optimisation framework to achieve an updated calibration for the VVT control. The cycle segment was identified as an area with high NOx emissions. The optimisation framework was developed around a Mean Value Engine Model with representative engine controls which was validated against an engine tested on a dynamometer. The aim of this study was to demonstrate a practical benefit without having to significantly change the existing engine control strategy. Offline optimization with the MVEM model allows exploitation of workstation computational performance to effectively explore the calibration space, reducing both time and investment in engine testing. The initial optimization results show a strong dominance of both fuel and NOx objectives with a potential reduction in fuel consumption and engine out NOx emissions of up to 5% and 18% respectively compared to the original steady-state based VCT calibration. Engine experimental results have confirmed that NOx emissions can be significantly reduced without any significant detriment to fuel economy over this 2min transient

Coat colour in dogs: identification of the Merle locus in the Australian shepherd breed

BACKGROUND: Coat colours in canines have many natural phenotypic variants. Some of the genes and alleles involved also cause genetic developmental defects, which are also observed in humans and mice. We studied the genetic bases of the merle phenotype in dogs to shed light on the pigmentation mechanisms and to identify genes involved in these complex pathways. The merle phenotype includes a lack of eumelanic pigmentation and developmental defects, hearing impairments and microphthalmia. It is similar to that observed in microphthalmia mouse mutants. RESULTS: Taking advantage of the dog as a powerful genetic model and using recently available genomic resources, we investigated the segregation of the merle phenotype in a five-generation pedigree, comprising 96 sampled Australian shepherd dogs. Genetic linkage analysis allowed us to identify a locus for the merle phenotype, spanning 5.5 megabases, at the centromeric tip of canine chromosome 10 (CFA10). This locus was supported by a Lod score of 15.65 at a recombination fraction θ = 0. Linkage analysis in three other breeds revealed that the same region is linked to the merle phenotype. This region, which is orthologous to human chromosome 12 (HSA12 q13-q14), belongs to a conserved ordered segment in the human and mouse genome and comprises several genes potentially involved in pigmentation and development. CONCLUSION: This study has identified the locus for the merle coat colour in dogs to be at the centromeric end of CFA10. Genetic studies on other breeds segregating the merle phenotype should allow the locus to be defined more accurately with the aim of identifying the gene. This work shows the power of the canine system to search for the genetic bases of mammalian pigmentation and developmental pathways

Delivery of Dark Material to Vesta via Carbonaceous Chondritic Impacts

NASA's Dawn spacecraft observations of asteroid (4) Vesta reveal a surface with the highest albedo and color variation of any asteroid we have observed so far. Terrains rich in low albedo dark material (DM) have been identified using Dawn Framing Camera (FC) 0.75 {\mu}m filter images in several geologic settings: associated with impact craters (in the ejecta blanket material and/or on the crater walls and rims); as flow-like deposits or rays commonly associated with topographic highs; and as dark spots (likely secondary impacts) nearby impact craters. This DM could be a relic of ancient volcanic activity or exogenic in origin. We report that the majority of the spectra of DM are similar to carbonaceous chondrite meteorites mixed with materials indigenous to Vesta. Using high-resolution seven color images we compared DM color properties (albedo, band depth) with laboratory measurements of possible analog materials. Band depth and albedo of DM are identical to those of carbonaceous chondrite xenolith-rich howardite Mt. Pratt (PRA) 04401. Laboratory mixtures of Murchison CM2 carbonaceous chondrite and basaltic eucrite Millbillillie also show band depth and albedo affinity to DM. Modeling of carbonaceous chondrite abundance in DM (1-6 vol%) is consistent with howardite meteorites. We find no evidence for large-scale volcanism (exposed dikes/pyroclastic falls) as the source of DM. Our modeling efforts using impact crater scaling laws and numerical models of ejecta reaccretion suggest the delivery and emplacement of this DM on Vesta during the formation of the ~400 km Veneneia basin by a low-velocity (<2 km/sec) carbonaceous impactor. This discovery is important because it strengthens the long-held idea that primitive bodies are the source of carbon and probably volatiles in the early Solar System.Comment: Icarus (Accepted) Pages: 58 Figures: 15 Tables: