10,741 research outputs found
Raviart Thomas Petrov-Galerkin Finite Elements
The general theory of Babu\v{s}ka ensures necessary and sufficient conditions
for a mixed problem in classical or Petrov-Galerkin form to be well posed in
the sense of Hadamard. Moreover, the mixed method of Raviart-Thomas with
low-level elements can be interpreted as a finite volume method with a
non-local gradient. In this contribution, we propose a variant of type
Petrov-Galerkin to ensure a local computation of the gradient at the interfaces
of the elements. The in-depth study of stability leads to a specific choice of
the test functions. With this choice, we show on the one hand that the mixed
Petrov-Galerkin obtained is identical to the finite volumes scheme "volumes
finis \`a 4 points" ("VF4") of Faille, Gallo\"uet and Herbin and to the
condensation of mass approach developed by Baranger, Maitre and Oudin. On the
other hand, we show the stability via an inf-sup condition and finally the
convergence with the usual methods of mixed finite elements.Comment: arXiv admin note: text overlap with arXiv:1710.0439
Evidence Propagation and Consensus Formation in Noisy Environments
We study the effectiveness of consensus formation in multi-agent systems
where there is both belief updating based on direct evidence and also belief
combination between agents. In particular, we consider the scenario in which a
population of agents collaborate on the best-of-n problem where the aim is to
reach a consensus about which is the best (alternatively, true) state from
amongst a set of states, each with a different quality value (or level of
evidence). Agents' beliefs are represented within Dempster-Shafer theory by
mass functions and we investigate the macro-level properties of four well-known
belief combination operators for this multi-agent consensus formation problem:
Dempster's rule, Yager's rule, Dubois & Prade's operator and the averaging
operator. The convergence properties of the operators are considered and
simulation experiments are conducted for different evidence rates and noise
levels. Results show that a combination of updating on direct evidence and
belief combination between agents results in better consensus to the best state
than does evidence updating alone. We also find that in this framework the
operators are robust to noise. Broadly, Yager's rule is shown to be the better
operator under various parameter values, i.e. convergence to the best state,
robustness to noise, and scalability.Comment: 13th international conference on Scalable Uncertainty Managemen
Z-graded differential geometry of quantum plane
In this work, the Z-graded differential geometry of the quantum plane is
constructed. The corresponding quantum Lie algebra and its Hopf algebra
structure are obtained. The dual algebra, i.e. universal enveloping algebra of
the quantum plane is explicitly constructed and an isomorphism between the
quantum Lie algebra and the dual algebra is given.Comment: 17 page
Programme cantonal diabĂšte dans le canton de Vaud indicateurs pour le suivi et le baromĂštre : rapport final
Le Programme cantonal DiabÚte souhaite collecter des indicateurs afin d'objectiver son suivi et produire un BaromÚtre DiabÚte Vaud qui serait publié et distribué périodiquement à un public large. Ce rapport présente les indicateurs suggérés par l'IUMSP, mandaté afin d'établir une liste raisonnée d'indicateurs sur le diabÚte pour le canton de Vaud. La sélection d'indicateurs s'est faite d'aprÚs plusieurs critÚres, parmi lesquels la disponibilité des indicateurs actuelle et à long terme, ainsi que leur pertinence avérée par la littérature. Ce rapport décrit les résultats pour les indicateurs sélectionnés, ainsi que les informations nécessaires à leur compréhension : source, fréquence de mise à disposition, méthode de calcul, limites, références éventuelles. Parmi les indicateurs décrits dans ce rapport, certains sont proposés comme spécialement pertinents à inclure dans le futur BaromÚtre DiabÚte Vaud. Aussi, une suggestion de présentation de ces indicateurs (fiches descriptives) est articulée pour ce dernier
Techniques to improve technological and sanitary quality
Agronomical ways for better quality and safety
Choice of cultivar is an efficient way to obtain higher grain quality. Intercropping legumes (grain or forage) improves weed competition and N availability for wheat crop or succeeding crop. Green manure can be an effective alternative to farmyard manure. Fertilization with readily available nitrogen improves yield and quality when water is available. Reduced tillage affects soil fertility and wheat yield but has little effects on grain quality.
Technological ways for better quality and safety
Milling process strongly influences flour characteristics. Stone milling improves nutritive value; characteristics remain very stable independent of the milling yield. Flour characteristics from roller milling appear very susceptible to the milling yield. Increasing the milling yield in the aim of enriching nutritional quality has a detrimental effect either on safety (DON) or on bread-making quality (bread volume)
Outer Approximations of Coherent Lower Probabilities Using Belief Functions
We investigate the problem of outer approximating a coherent lower probability with a more tractable model. In particular, in this work we focus on the outer approximations made by belief functions. We show that they can be obtained by solving a linear programming problem. In addition, we consider the subfamily of necessity measures, and show that in that case we can determine all the undominated outer approximations in a simple manner
Effects of Contact Pressure, Plastic Strain and Sliding Velocity on Sticking in Cold Forging of Aluminium Billet
AbstractHot rolling of stainless steel is one of the most important steps in manufacturing process regarding surface quality of the product. Stabilised ferritic stainless steels are widely used in automotive and cosmetic appliances but are also concerned by sticking phenomenon. These grades, having high dry corrosion and creep resistance, are enriched in specific chemical elements such as Cr, Nb or Ti, limiting also slab oxidation during hot rolling. Nevertheless, the mastered oxidation of slab surface is a way to protect metal surface from direct contact with rolls. In order to better understand initiation of sticking, a first campaign was based on topography and rolls surface state wear analysis. This study revealed that sticking initiation is not due to the presence of roll scratches which depth is higher than oxide layer thickness. Indeed, the probability that roll scratches are deeper than oxide layer thickness is very low. In a second time, a pilot was designed, reproducing tribological conditions of a roll bite, to better understand mechanisms that initiate sticking. Keeping in mind the importance of rolls and slab surface state, this pilot is able to use specimen taking from industrial products, having the original oxide layer surface. This second study highlighted the major role of silicon oxides on scale adherence and the high heterogeneity of this scale layer in thickness and in chemical composition
Technological quality of organic wheat in Europe
The demand for high quality organic bread wheat is increasing. The quality level of organic wheat harvested in EU is mainly dependant on variety, environmental conditions and agronomic practices. In some countries, protein content and composition, influencing technological value, are equivalent to those produced under conventional practices. Beside agronomical techniques, technological processes can help to maintain a good quality. Pre-treatments before milling such as debranning were found to be efficient in reducing DON contamination. The project highlighted the necessity to redefine the methods to assess the quality of organic wheat
Improved sensitivity of H.E.S.S.-II through the fifth telescope focus system
The Imaging Atmospheric Cherenkov Telescope (IACT) works by imaging the very
short flash of Cherenkov radiation generated by the cascade of relativistic
charged particles produced when a TeV gamma ray strikes the atmosphere. This
energetic air shower is initiated at an altitude of 10-30 km depending on the
energy and the arrival direction of the primary gamma ray. Whether the best
image of the shower is obtained by focusing the telescope at infinity and
measuring the Cherenkov photon angles or focusing on the central region of the
shower is a not obvious question. This is particularly true for large size IACT
for which the depth of the field is much smaller. We address this issue in
particular with the fifth telescope (CT5) of the High Energy Stereoscopic
System (H.E.S.S.); a 28 m dish large size telescope recently entered in
operation and sensitive to an energy threshold of tens of GeVs. CT5 is equipped
with a focus system, its working principle and the expected effect of focusing
depth on the telescope sensitivity at low energies (50-200 GeV) is discussed.Comment: In Proceedings of the 33rd International Cosmic Ray Conference
(ICRC2013), Rio de Janeiro (Brazil
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