Search results for "COMPRESSION"

Global Existence for Nonlinear Parabolic Problems With Measure Data– Applications to Non-uniqueness for Parabolic Problems With Critical Gradient ter…

2011

Abstract In the present article we study global existence for a nonlinear parabolic equation having a reaction term and a Radon measure datum: where 1 < p < N, Ω is a bounded open subset of ℝN (N ≥ 2), Δpu = div(|∇u|p−2∇u) is the so called p-Laplacian operator, sign s ., ϕ(ν0) ∈ L1(Ω), μ is a finite Radon measure and f ∈ L∞(Ω×(0, T)) for every T > 0. Then we apply this existence result to show wild nonuniqueness for a connected nonlinear parabolic problem having a gradient term with natural growth.

Efficiency of H center stabilization in alkali halide crystals at low-temperature uniaxial deformation

2020

The efficiency of stabilization of H centers as well as its dependence on the degree of uniaxial deformation are considered within the framework of the modified geometric model of alkali halides. It is shown that stabilization of H centers is difficult in KI and RbI crystals, while in other NaCl-type crystals it becomes quite probable. Under uniaxial deformation, the interstitial space, in which the defect will be located, decreases, and the efficiency decrease. In the case of cesium halides, the orientation of the H centers takes place predominantly in the direction; therefore, the criteria for their stabilization differ from the NaCl-type alkali halide crystals. According to calculations,…

Synergistic effect of fiber content and length on mechanical and water absorption behaviors of Phoenix sp. fiber-reinforced epoxy composites

2016

Phoenix sp. fiber-reinforced epoxy composites have been manufactured using compression molding technique. The effect of reinforcement volume content (0%, 10%, 20%, 30%, 40%, and 50%) and size (300 µm particles, 10 mm, 20 mm, and 30 mm fibers) on quasi-static and dynamic mechanical properties was investigated. Moreover, the water absorption properties of composites were analyzed at different environmental conditions (10℃, 30℃, and 60℃). For each reinforcement size, composites loaded with 40% in volume show highest tensile and flexural properties. Furthermore, composites with 300 µm particles present the best impact properties and the lowest water absorption, regardless of the environmental …

2021

Intracratonic basins tend to subside much longer than the timescale predicted by thermal relaxation of the lithosphere. Many hypotheses have been suggested to explain their longevity, yet few have been tested using quantitative thermo-mechanical numerical models, which capture the dynamic of the lithosphere. Lithospheric-scale geodynamic modelling preserving the tectono-stratigraphic architecture of these basins is challenging because they display only few kilometres of subsidence over 1000 of km during time periods exceeding 250 Myr. Here we present simulations that are designed to examine the relative role of thermal anomaly, tectonics and heterogeneity of the lithosphere on the dynamics …

Is there a global carbonate layer in the oceanic mantle?

2021

co-auteur étranger; International audience; Previous modeling of carbonate subduction by high‐pressure experimentation has allowed to propose scenarios for bulk carbon return to the mantle, but the detailed transfer mechanisms have seldom been studied. We monitored carbonate – silicate reactions by combining high‐pressure experiments and synchrotron‐based x‐ray diffraction. Carbonates break down at moderate pressure and high temperature and CO2 is trapped at grain boundaries. Further isothermal compression yields melting, which may control continuous carbon introduction, first in the mantle wedge, and next, away from the wedge. Carbon presence has been discussed in a variety of magmatic con…

Tectonics of the Northern Bresse region (France) during the Alpine cycle

2003

International audience; Combining fieldwork and surface data, we have reconstructed the Cenozoic structural and tectonic evolution of the Northern Bresse. Analysis of drainage network geometry allowed to detect three major fault zones trending NE-SW, E-W and NW-SE, and smooth folds with NNE trending axes, all corroborated with shallow well data in the graben and fieldwork on edges. Cenozoic paleostress succession was determined through fault slip and calcite twin inversions, taking into account data of relative chronology. A N-S major compression, attributed to the Pyrenean orogenesis, has activated strike-slip faults trending NNE along the western edge and NE-SW in the graben. After a tran…

Étude paléobotanique d’une lentille argileuse cénomanienne de la carrière de Hucheloup, Maine-et-Loire, NO France : implications taxonomiques, strati…

2017

International audience; A Cenomanian clay lens in Hucheloup Quarry (Maine-et-Loire, north-western France) has yielded 82 foliar compressions and impressions, of which 62 were identified at several taxonomic levels. The plants are ascribed to diverse Pinales (27%), ferns (27%), Ginkgoales (26%), angiosperms (19%) and Cycadales (1%). The most abundant species in the assemblage are Frenelopsis alata (K. Feistmantel) E. Knobloch emend. J. Kvaček (Pinales) and Eretmophyllum obtusum (Velenovský) J. Kvaček (syn. E. andegavense Pons, Bourreau et Broutin) (Ginkgoales). Wood fragments, along with very well-preserved cuticles, have also been recovered and identified. The specimens are usually very fra…

Impact of gas emboli and hyperbaric treatment on respiratory function of loggerhead sea turtles (Caretta caretta)

2018

We investigated lung function in bycaught sea turtles with and without gas emboli. Hyperbaric O2 treatment significantly improves lung function. Pulmonary function testing may be a useful diagnostic tool to assess fisheries induced trauma.

Cranial suture biomechanics inMetoposaurus krasiejowensis(Temnospondyli, Stereospondyli) from the upper Triassic of Poland

2019

Cranial sutures connect adjacent bones of the skull and play an important role in the absorption of stresses that may occur during different activities. The Late Triassic temnospondyl amphibian Metoposaurus krasiejowensis has been extensively studied over the years in terms of skull biomechanics, but without a detailed description of the function of cranial sutures. In the present study, 34 thin sections of cranial sutures were examined in order to determine their histovariability and interpret their biomechanical role in the skull. The histological model was compared with three-dimensional-finite element analysis (FEA) simulations of the skull under bilateral and lateral biting as well as …

Novel Insights Into Gas Embolism in Sea Turtles: First Description in Three New Species

2020

The recent finding of gas embolism and decompression sickness in loggerhead sea turtles (Caretta caretta) in the Mediterranean Sea challenged the conventional understanding of marine vertebrate diving physiology. Additionally, it brought to light a previously unknown source of mortality associated with fisheries bycatch for this vulnerable species. In this paper, we use ultrasonography to describe gas embolism in a leatherback sea turtle (Dermochelys coriacea), a green sea turtle (Chelonia mydas) and an olive ridley sea turtle (Lepidochelys olivacea) from accidental capture in a gillnet, bottom trawl and pair-bottom trawl respectively. This is the first description of this condition in thes…