Search results for "Cone"
showing 10 items of 772 documents
Effect of the surrounding aeration on microcapillary electrochemical cell experiments
2008
In the microelectrochemical capillary cell technique a silicone rubber gasket is used to avoid any electrolyte leakage between the pulled glass capillary and the working electrode (the metallic tested material). In this study, it is demonstrated that the oxygen reduction reaction (ORR) is strongly affected by the use of the silicone rubber. Experiments under a surrounding argon gas shielding of the pulled capillary in contact with the metallic surface have been performed showing a large effect on the ORR. Considering the high permeation rate of oxygen through silicone, the decrease of the reaction rate observed experimentally was validated by FEM modelling assuming that the air/silicone/wat…
A 10-Year Cone Beam Computerized Tomography Observation of the Buccal Bony Wall of an Immediately Placed Implant at the Anterior Maxilla: A Case Repo…
2017
Since the introduction of immediate implant placements, the buccal bony wall has been a major consideration for success due to its correlation with soft tissue contour and color. This report presents the stability of the buccal wall thickness of an immediately placed implant at the anterior maxilla over 10 years. Although the width of the buccal wall decreased at the 2-year post-op follow-up, it remained stable afterward according to cone beam computerized tomography (CBCT) scans. Hence, this report suggests that ensuring adequate bony wall thickness with bone augmentation and fixture position may promise the longevity of the buccal bony wall and surrounding soft tissue in an immediate impl…
Asymptotics of accessibility sets along an abnormal trajectory
2001
We describe precisely, under generic conditions, the contact of the accessibility set at time $T$ with an abnormal direction, first for a single-input affine control system with constraint on the control, and then as an application for a sub-Riemannian system of rank 2. As a consequence we obtain in sub-Riemannian geometry a new splitting-up of the sphere near an abnormal minimizer $\gamma$ into two sectors, bordered by the first Pontryagin's cone along $\gamma$, called the $\xLinfty$-sector and the $\xLtwo$-sector. Moreover we find again necessary and sufficient conditions of optimality of an abnormal trajectory for such systems, for any optimization problem.
Constrained differential inclusions with nonlocal initial conditions
2017
International audience; We show existence for the perturbed sweeping process with nonlocal initial conditions under very general hypotheses. Periodic, anti-periodic, mean value and multipoints conditions are included in this study. We give abstract results for differential inclusions with nonlocal initial conditions through bounding functions and tangential conditions. Some applications to differential complementarity systems and to vector hysteresis are given.
Characterization of the Clarke regularity of subanalytic sets
2017
International audience; In this note, we will show that for a closed subanalytic subset $A \subset \mathbb{R}^n$, the Clarke tangential regularity of $A$ at $x_0 \in A$ is equivalent to the coincidence of the Clarke's tangent cone to $A$ at $x_0$ with the set \\$$\mathcal{L}(A, x_0):= \bigg\{\dot{c}_+(0) \in \mathbb{R}^n: \, c:[0,1]\longrightarrow A\;\;\mbox{\it is Lipschitz}, \, c(0)=x_0\bigg\}.$$Where $\dot{c}_+(0)$ denotes the right-strict derivative of $c$ at $0$. The results obtained are used to show that the Clarke regularity of the epigraph of a function may be characterized by a new formula of the Clarke subdifferential of that function.
Differential inclusions involving normal cones of nonregular sets in Hilbert spaces
2017
This thesis is dedicated to the study of differential inclusions involving normal cones of nonregular sets in Hilbert spaces. In particular, we are interested in the sweeping process and its variants. The sweeping process is a constrained differential inclusion involving normal cones which appears naturally in several applications such as elastoplasticity, electrical circuits, hysteresis, crowd motion, etc.This work is divided conceptually in three parts: Study of positively alpha-far sets, existence results for differential inclusions involving normal cones and characterizations of Lyapunov pairs for the sweeping process. In the first part (Chapter 2), we investigate the class of positivel…
Infection with acanthocephalans increases the vulnerability of Gammarus pulex (Crustacea, Amphipoda) to non-host invertebrate predators.
2008
SUMMARYPhenotypic alterations induced by parasites in their intermediate hosts often result in enhanced trophic transmission to appropriate final hosts. However, such alterations may also increase the vulnerability of intermediate hosts to predation by non-host species. We studied the influence of both infection with 3 different acanthocephalan parasites (Pomphorhynchus laevis, P. tereticollis, and Polymorphus minutus) and the availability of refuges on the susceptibility of the amphipod Gammarus pulex to predation by 2 non-host predators in microcosms. Only infection with P. laevis increased the vulnerability of amphipods to predation by crayfish, Orconectes limosus. In contrast, in the ab…
Physical, chemical and mechanical evolution of the fuel-cladding interface in irradiated PWR fuel rods
2022
During the fuel irradiation in nuclear reactor, the fuel-cladding assembly is exposed to several irradiation-induced modifications. The fuel swelling coupled with cladding creep leads to a contact between the fuel and the cladding. The oxygen transport from the UO2 fuel to the zirconium layer induces progressively the Zr-cladding oxidation. This oxidation is initially local with the formation of islets. Then, with the increasing burnup of the fuel, it conducts to a continuous layer of about 8-µm thickness, localized at the fuel-cladding interface. At high burnup, zirconia growths anchor themselves in the periphery of the fuel (which is restructured) leading to pellet/cladding interlocking. …
Search for biological signature of the degradation of chlordecone in soil of the French West Indies
2015
The use of chlordecone (CLD) to eradicate the weevil populations in the banana plantations in the French West Indies (Guadeloupe and Martinique) between 1972 and 1993 led to the contamination of the soil and the environment. This very hydrophobic organochlorine insecticide persists in the soil where it slowly transfers not only to the water resources but also to terrestrial and aquatic biota (plants, animals, fishes, shellfishes). Deemed “non-degradable”, CLD is resistant to photolysis, hydrolysis and biodegradation. To date, there is no method to remediate the 20,000 hectares of polluted soil with this insecticide. Given the extent of CLD pollution, biological decontamination processes app…