168 research outputs found
Ensuring Query Compatibility with Evolving XML Schemas
During the life cycle of an XML application, both schemas and queries may
change from one version to another. Schema evolutions may affect query results
and potentially the validity of produced data. Nowadays, a challenge is to
assess and accommodate the impact of theses changes in rapidly evolving XML
applications.
This article proposes a logical framework and tool for verifying
forward/backward compatibility issues involving schemas and queries. First, it
allows analyzing relations between schemas. Second, it allows XML designers to
identify queries that must be reformulated in order to produce the expected
results across successive schema versions. Third, it allows examining more
precisely the impact of schema changes over queries, therefore facilitating
their reformulation
Smart Trip Alternatives for the Curious
International audienceWhen searching for flights, current systems often suggest routesinvolving waiting times at stopovers. There might exist alternative routes which aremore attractive from a touristic perspective because their duration isnot necessarily much longer while offering enough time in anappropriate place. Choosing among suchalternatives requires additional planning efforts to make sure thate.g. points of interest can conveniently be reached in theallowed time frame. We present a system that automatically computes smart tripalternatives between any two cities. To do so, it searchespoints of interest in large semantic datasets considering theset of accessible areas around each possible layover. It then elects feasible alternatives and displays theirdifferences with respect to the default trip
NormativitĂ©s et usages judiciaires des technologies : lâexemple controversĂ© de la neuroimagerie en France et au Canada
Lâobservation du systĂšme nerveux, de son mĂ©tabolisme et de certaines de ses structures est possible grĂące Ă la neuroimagerie. Une littĂ©rature importante issue du « neurodroit » vĂ©hicule des imaginaires et des fantasmes relatifs aux possibilitĂ©s judiciaires quâoffriraient ces technologies. Quâil sâagisse de dĂ©tection du mensonge, dâidentification cĂ©rĂ©brale des individus dangereux ou encore de prĂ©diction de comportements dĂ©viants, la neuroimagerie, en lâĂ©tat actuel des technologies, ne peut pourtant ĂȘtre sĂ©rieusement conçue comme pouvant faire lâobjet de telles applications.
Lâutilisation de la neuroimagerie dans le cadre dâexpertises est nĂ©anmoins une rĂ©alitĂ©, dans les tribunaux canadiens comme dans la loi française.
Cette thĂšse souligne que les conceptions des technologies dont tĂ©moignent les deux systĂšmes juridiques Ă©tudiĂ©s sâavĂšrent lacunaires, ce qui engendre des risques. Elle Ă©voque les conditions du recours Ă une normativitĂ© extra-juridique, la normalisation technique, qui pourrait sâĂ©laborer dans ce contexte controversĂ©, et esquisse les traits dâun dialogue amĂ©liorĂ© entre les normativitĂ©s juridique et technologique.Neuroimaging allows the
observation of the nervous system, of
both its metabolism and some of its
structures. An important literature in
âneurolawâ conveys illusions and
fantaisies about the judicial possibilities
that imaging technologies would contain.
Whether it is about lies detection,
cerebral identifications of dangerous
individuals through their neurobiology or
predictions of criminal behaviors,
neuroimaging, in the current state of
technologies, can not be seriously
conceived as being able to offer such
applications.
Judicial uses of neuroimaging through
expertise are a reality nonetheless, in
Canadian courts as in French law.
This thesis emphasizes that the
conceptions of imaging technologies
integrated in the two legal systems
studied are incomplete, which creates an
important amount of risks. It discusses the
conditions for the use of an extra-legal
normativity, the international technical
standardization, which could be
elaborated in this particular and
controversial context, and outlines several
features of an increased dialogue
between legal and technological norm
Constrained Differentially Private Federated Learning for Low-bandwidth Devices
Federated learning becomes a prominent approach when different entities want
to learn collaboratively a common model without sharing their training data.
However, Federated learning has two main drawbacks. First, it is quite
bandwidth inefficient as it involves a lot of message exchanges between the
aggregating server and the participating entities. This bandwidth and
corresponding processing costs could be prohibitive if the participating
entities are, for example, mobile devices. Furthermore, although federated
learning improves privacy by not sharing data, recent attacks have shown that
it still leaks information about the training data. This paper presents a novel
privacy-preserving federated learning scheme. The proposed scheme provides
theoretical privacy guarantees, as it is based on Differential Privacy.
Furthermore, it optimizes the model accuracy by constraining the model learning
phase on few selected weights. Finally, as shown experimentally, it reduces the
upstream and downstream bandwidth by up to 99.9% compared to standard federated
learning, making it practical for mobile systems.Comment: arXiv admin note: text overlap with arXiv:2011.0557
Knowledge Enhanced Graph Neural Networks
Graph data is omnipresent and has a large variety of applications such as
natural science, social networks or semantic web. Though rich in information,
graphs are often noisy and incomplete. Therefore, graph completion tasks such
as node classification or link prediction have gained attention. On the one
hand, neural methods such as graph neural networks have proven to be robust
tools for learning rich representations of noisy graphs. On the other hand,
symbolic methods enable exact reasoning on graphs. We propose KeGNN, a
neuro-symbolic framework for learning on graph data that combines both
paradigms and allows for the integration of prior knowledge into a graph neural
network model. In essence, KeGNN consists of a graph neural network as a base
on which knowledge enhancement layers are stacked with the objective of
refining predictions with respect to prior knowledge. We instantiate KeGNN in
conjunction with two standard graph neural networks: Graph Convolutional
Networks and Graph Attention Networks, and evaluate KeGNN on multiple benchmark
datasets for node classification
Modélisation unidimensionnelle d'un collecteur solaire aéraulique
Les collecteurs solaires aĂ©rauliques perforĂ©s permettent de prĂ©chauffer de lâair. Lâair en question est aspirĂ© Ă travers une plaque perforĂ©e et chauffĂ©e par le rayonnement solaire. Lorsque la plaque perforĂ©e est semi-transparente, le mur derriĂšre celle-ci peut ĂȘtre vu et elle confĂšre ainsi un avantage esthĂ©tique par rapport aux collecteurs opaques. Ceci faciliterait lâacceptation de ce type de collecteur et par consĂ©quent rĂ©duirait la consommation Ă©nergĂ©tique des bĂątiments sur lesquels ils seraient installĂ©s.
Au meilleur de notre connaissance, cette Ă©tude prĂ©sente la premiĂšre description des phĂ©nomĂšnes physiques existant dans les collecteurs solaires aĂ©rauliques perforĂ©s transparents (ci-aprĂšs TTC, selon lâacronyme anglais) ainsi quâune formulation de ceux-ci par des bilans thermiques. Aux phĂ©nomĂšnes dĂ©jĂ connus par lâĂ©tude des collecteurs solaires aĂ©rauliques perforĂ©s opaques (ci-aprĂšs UTC, selon lâacronyme anglais), la transmissivitĂ© de la plaque, lâabsorptivitĂ©, lâĂ©missivitĂ© et la rĂ©flectivitĂ© du mur ont Ă©tĂ© ajoutĂ©es ainsi que lâĂ©change thermique par convection au niveau du mur. Pour la modĂ©lisation, un certain nombre de simplifications ont Ă©tĂ© faites quand Ă lâĂ©coulement et aux Ă©changes thermiques par rayonnement.
Le collecteur est subdivisĂ© en volumes de contrĂŽle unidimensionnels linĂ©airement alignĂ©s et les bilans thermiques et de masse sont effectuĂ©s sur chacun dâeux. La formulation des bilans est linĂ©arisĂ©e de maniĂšre Ă produire un systĂšme matriciel que lâon peut rĂ©soudre par inversion et de maniĂšre itĂ©rative.
Afin de comprendre les spĂ©cificitĂ©s des TTC par rapport aux UTC, la transmissivitĂ© de la plaque, lâabsorptivitĂ© du mur, la vitesse de succion ainsi que le rayonnement solaire incident sont rendus variables. Les rĂ©sultats montrent que ce dernier avait trĂšs peu dâincidence sur le rendement du collecteur. Il nâinfluence que la quantitĂ© dâĂ©nergie disponible. Les paramĂštres optiques influent cependant sur la capacitĂ© dâabsorber cette Ă©nergie. LâabsorptivitĂ© globale du collecteur est dĂ©finie pour rendre compte de la capacitĂ© du collecteur Ă absorber le rayonnement solaire. Ainsi, plus la transmissivitĂ© de la plaque augmente, plus lâabsorptivitĂ© globale du collecteur diminue. Cette diminution est dâautant plus prononcĂ©e que lâabsorptivitĂ© du mur est faible en raison de ce que le rayonnement solaire rĂ©flĂ©chi sur le mur retraverse la plaque avec la mĂȘme transmissivitĂ© puisque le rayonnement solaire rĂ©flĂ©chi ne change pas de longueur dâonde. Enfin, la vitesse de succion dĂ©termine la capacitĂ© de lâair Ă rĂ©cupĂ©rer la chaleur captĂ©e par le mur et la plaque. Plus cette vitesse est Ă©levĂ©e, meilleures sont les performances.
Les premiers rĂ©sultats sur les paramĂštres optiques et la revue de ces simplifications permettent dâĂ©tablir une sĂ©rie de recommandations et avenues de recherche qui complĂšteraient le modĂšle et valideraient ces rĂ©sultats numĂ©riques
SPARUB: SPARQL UPDATE Benchmark
One aim of the RDF data model, as standardized by the W3C, is to facilitate the evolution of data over time without requiring all the data consumers to be changed. To this end, one of the latest addition to the SPARQL standard query language is an update language for RDF graphs. The research on efficient and scalable SPARQL evaluation methods increasingly relies on standardized methodologies for benchmarking and comparing systems. However, current RDF benchmarks do not support graphs updates. We propose and share SPARUB: a benchmark for the SPARQL UPDATE language on RDF graphs. The aim of SPARUB is not to be yet another RDF benchmark. Instead it provides the mean to automatically extend and improve existing RDF benchmarks along a new dimension of data updates, while preserving their structure and query scenarios
A Method to Quantitatively Evaluate Geo Augmented Reality Applications
International audienceWe propose a method for quantitatively assessing the quality of Geo AR browsers. Our method aims at measuring the impact of attitude and position estimations on the rendering precision of virtual features. We report on lessons learned by applying our method on various AR use cases with real data. Our measurement technique allows to shedding light on the limits of what can be achieved in Geo AR with current technologies. This also helps in identifying interesting perspectives for the further development of high-quality Geo AR applications
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