1,715 research outputs found
From medical data to simple virtual mock-up of scapulo-humeral joint
The surgical operations of shoulder joint are guided by various principles: osteosynthesis in the case of fracture, osteotomy in order to correct a deformation or to modify the functioning of the joint, or implementation of articular prosthesis. At the end of the twentieth century, many innovations in the domains of biomechanics and orthopedic surgery have been performed. Nevertheless, theoretical and practical problems may appear during the operation (visual field of surgeon is very limited, quality and shape of the bone is variable depending on the patient). Biomechanical criteria of success are defined for each intervention. For example, the installation with success of prosthetic implant will be estimated according to the degree of mobility of the new articulation, the movements of this articulation being function of the shape of the prosthesis and of its position on its osseous support. It is not always easy to optimize the preparation of the surgical operation for every patient, and a preliminary computer simulation would allow helping the surgeon in its choices and its preparation of the intervention. The techniques of virtual reality allow a high degree of immersion and allow envisaging the development of a navigation device during the operating act
Transport of Water and Gases through EVA/PVC blend films â Permeation and DSC investigations.
The transport of water vapor and gases (oxygen and carbon dioxide) through poly(ethylene-co-vinyl acetate) (EVA) films of different VA content, poly(vinylchloride) (PVC) and EVA/PVC blend films, was analysed from permeation measurements.
A plasticization effect of water on the material was observed for EVA films with more than 19% wt. of VA content and for the EVA/PVC blends, while for gas permeation practically all the experimental curves are characterized by a constant diffusion coefficient, whatever the VA content of the copolymer used. The increase in water absorption with the VA content leads to a steady increase in the water permeability of the EVA copolymers. By mixing the glassy PVC polymer with the EVA copolymer (in a rubbery state) reduced water and gas permeability is observed, resulting mainly from the decrease of the diffusivity due to the low segment mobility of the dense PVC material able to create hydrogen bonds between the hydrogen atoms and the Cl-substituted carbon of PVC with VA carbonyls. Compared to EVA copolymers, the EVA/PVC blends with equivalent VA contents are better in terms of selectivity
Parametric study of the mechanical properties of nanocrystalline TiN/CrN multilayer coatings with a special focus on the effect of coating thickness and substrate roughness
In a plot to improve the performance of steel mechanical parts subject to aggressive friction solicitations, three batches of deposits of TiN and CrN layers on steel substrates with two different roughnesses have been obtained using reactive DC magnetron sputtering. The present study was conducted to determine the effect of varying TiN/CrN multilayer coatings thickness (varying modulated period Î and interlayer thickness), on their mechanical and tribological properties. The morphological and the structural properties were analyzed using scanning electron microscopy (SEM) and X-ray diffraction (XRD). The nanoindentation measurements displayed improvement in hardness (> 40 GPa) and Youngâs modulus (> 600 GPa) for the coating with Î â
12 nm (TiN Î/2 â
7.5 nm + CrN Î/2 â
4.5 nm) thickness and the higher number (300) of interfaces, deposited on the rougher substrate. Its low coating damage under the scratch test, associated with its estimated adhesion work (Wad), indicated a good cohesive/adhesive strength and improved structural and mechanical properties
Process of Facilitated Extraction of Vanadium Ions through Supported Liquid Membranes: Parameters and Mechanism
To conduct experiments related to the facilitated extraction phenomenon of vanadium ions (VO2+), three supported liquid membranes (SLMs) were prepared, each containing 0.01âM of methyl cholate (MC), resorcinarene (RESO), or trioctylamine (TOA) as extractive agents. Kinetic and thermodynamic models were developed, based on the interaction of the substrate (VO2+) with the extractive agent T and the diffusion of the formed entity (TS) through the membrane. The experimental results verify the models, and to determine, macroscopic parameters, permeabilities (P) and initial fluxes (J0), and microscopic parameters, association constants (Kass) and apparent diffusion coefficients (Dâ) related to formed entities (TS) and their diffusion through the membrane organic phase. The experimental results indicate that the mechanism on the migration of the VO2+ ions through the membrane organic phase is based on the successive jumps of substrate, from one site to another of the extractive agent. To explain these results and understand the mechanism, we studied influence of temperature factor, and we determined activation parameters (Ea, ÎHâ , and ÎSâ ). The results show that this extraction phenomenon is governed by a structural term. Therefore, the membrane performance changes according to nature and structure of the association site presented by each of extractive agents
Interpreting Reactor Antineutrino Anomalies with STEREO data
Anomalies in past neutrino measurements have led to the discovery that theseparticles have non-zero mass and oscillate between their three flavors whenthey propagate. In the 2010's, similar anomalies observed in the antineutrinospectra emitted by nuclear reactors have triggered the hypothesis of theexistence of a supplementary neutrino state that would be sterile i.e. notinteracting via the weak interaction. The STEREO experiment was designed tostudy this scientific case that would potentially extend the Standard Model ofParticle Physics. Here we present a complete study based on our full set ofdata with significantly improved sensitivity. Installed at the ILL (InstitutLaue Langevin) research reactor, STEREO has accurately measured theantineutrino energy spectrum associated to the fission of 235U. Thismeasurement confirms the anomalies whereas, thanks to the segmentation of theSTEREO detector and its very short mean distance to the core (10~m), the samedata reject the hypothesis of a light sterile neutrino. Such a directmeasurement of the antineutrino energy spectrum suggests instead that biases inthe nuclear experimental data used for the predictions are at the origin of theanomalies. Our result supports the neutrino content of the Standard Model andestablishes a new reference for the 235U antineutrino energy spectrum. Weanticipate that this result will allow to progress towards finer tests of thefundamental properties of neutrinos but also to benchmark models and nucleardata of interest for reactor physics and for observations of astrophysical orgeo-neutrinos.<br
Interpreting Reactor Antineutrino Anomalies with STEREO data
Anomalies in past neutrino measurements have led to the discovery that these
particles have non-zero mass and oscillate between their three flavors when
they propagate. In the 2010's, similar anomalies observed in the antineutrino
spectra emitted by nuclear reactors have triggered the hypothesis of the
existence of a supplementary neutrino state that would be sterile i.e. not
interacting via the weak interaction. The STEREO experiment was designed to
study this scientific case that would potentially extend the Standard Model of
Particle Physics. Here we present a complete study based on our full set of
data with significantly improved sensitivity. Installed at the ILL (Institut
Laue Langevin) research reactor, STEREO has accurately measured the
antineutrino energy spectrum associated to the fission of 235U. This
measurement confirms the anomalies whereas, thanks to the segmentation of the
STEREO detector and its very short mean distance to the core (10~m), the same
data reject the hypothesis of a light sterile neutrino. Such a direct
measurement of the antineutrino energy spectrum suggests instead that biases in
the nuclear experimental data used for the predictions are at the origin of the
anomalies. Our result supports the neutrino content of the Standard Model and
establishes a new reference for the 235U antineutrino energy spectrum. We
anticipate that this result will allow to progress towards finer tests of the
fundamental properties of neutrinos but also to benchmark models and nuclear
data of interest for reactor physics and for observations of astrophysical or
geo-neutrinos.Comment: 21 pages, 13 figure
Improved FIFRELIN de-excitation model for neutrino applications
The precise modeling of the de-excitation of Gd isotopes is of great interest
for experimental studies of neutrinos using Gd-loaded organic liquid
scintillators. The FIFRELIN code was recently used within the purposes of the
STEREO experiment for the modeling of the Gd de-excitation after neutron
capture in order to achieve a good control of the detection efficiency. In this
work, we report on the recent additions in the FIFRELIN de-excitation model
with the purpose of enhancing further the de-excitation description.
Experimental transition intensities from EGAF database are now included in the
FIFRELIN cascades, in order to improve the description of the higher energy
part of the spectrum. Furthermore, the angular correlations between {\gamma}
rays are now implemented in FIFRELIN, to account for the relative anisotropies
between them. In addition, conversion electrons are now treated more precisely
in the whole spectrum range, while the subsequent emission of X rays is also
accounted for. The impact of the aforementioned improvements in FIFRELIN is
tested by simulating neutron captures in various positions inside the STEREO
detector. A repository of up-to-date FIFRELIN simulations of the Gd isotopes is
made available for the community, with the possibility of expanding for other
isotopes which can be suitable for different applications.Comment: Corrected typos on author names on arXiv metadat
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