Search results for "physics.class-ph"
showing 10 items of 334 documents
General invertible transformation and physical degrees of freedom
2017
An invertible field transformation is such that the old field variables correspond one-to-one to the new variables. As such, one may think that two systems that are related by an invertible transformation are physically equivalent. However, if the transformation depends on field derivatives, the equivalence between the two systems is nontrivial due to the appearance of higher derivative terms in the equations of motion. To address this problem, we prove the following theorem on the relation between an invertible transformation and Euler-Lagrange equations: If the field transformation is invertible, then any solution of the original set of Euler-Lagrange equations is mapped to a solution of …
Microfabrication of hybrid fluid membrane for microengines
2015
International audience; This paper describes the microfabrication and dynamic characterization of thick membranes providing a technological solution for microengines. The studied membranes are called hybrid fluid-membrane (HFM) and consist of two thin membranes that encapsulate an incompressible fluid. This work details the microelectromechanical system (MEMS) scalable fabrication and characterization of HFMs. The membranes are composite structures based on Silicon spiral springs embedded in a polymer (RTV silicone). The anodic bonding of multiple stacks of Si/glass structures, the fluid filling and the sealing have been demonstrated. Various HFMs were successfully fabricated and their dyna…
Global Linear Stability Analysis of the Flow Around a Superhydrophobic Circular Cylinder
2016
International audience; Over the last few years, superhydrophobic (SH) surfaces have been receiving an increasing attention in many scientific areas by virtue of their ability to enhance flow slip past solid walls and reduce the skin-friction drag. In the present study, a global linear-stability analysis is employed to investigate the influence of the SH-induced slip velocity on the primary instability of the 2D flow past a circular cylinder. The flow regions playing the role of 'wavemaker' are identified by considering the structural sensitivity of the unstable mode, thus highlighting the effect of slip on the global instability of the considered flow. In addition, a sensitivity analysis t…
Mechanical characterization of bio-based composite/metal laminates for an application in street furniture
2019
In this work, it is proposed to study the influence of three manufacturing parameters in the development of bio-basedcomposite/steel hybrids. These parameters arethe methodof assembly between composite and metal, the distribution of composite and steellayers throughthe thicknessof the hybrid,and the stacking sequence of the composite part of the hybrid. The study was conducted through impact tests at different energies and quasi-static three-point bending tests. For each of these parameters, the influenceon the mechanical properties of the hybrid is evaluated.The results show that these properties depend essentially on the relative distribution of steel and composite through the thickness.
Stream‐Discharge Surges Generated by Groundwater Flow
2019
International audience
Influence du vieillissement hygrothermique sur la tenue à l'impact de stratifiés quasi-isotropes/quasi homogènes
2011
International audience; La présente étude a pour objectif de déterminer l'influence du vieillissement hygrothermique sur la tolérance à l'impact de stratifiés possédant des propriétés particulières d'isotropie. Trois stratifications de 24 plis carbone/époxy ont été étudiées. Deux d'entre elles conduisent à des propriétés d'isotropie en membrane et en flexion, la troisième est isotrope en membrane et anisotrope en flexion. Les stratifiés obtenus après cuisson suivant le cycle préconisé par le fabricant ont été découpés pour obtenir des éprouvettes carrées destinées au vieillissement et à l'impact. Le vieillissement a été réalisé grâce à une enceinte climatique à une température de 70 °C sous…
Formation Kinetics of Mixed Self-Assembled Monolayers of Alkanethiols on GaAs(100)
2017
International audience; We report on the formation kinetics of mixed self-assembled monolayers (SAMs) comprising 16-mercaptohexadecanoic acid (MHDA) and 11-mercapto-1-undecanol (MUDO) thiols on GaAs(100) substrates. These compounds were selected for their potential in constructing highly selective and efficient architectures for biosensing applications. The molecular composition and quality of one-compound and mixed SAMs were determined by the Fourier transform infrared absorption spectroscopy measurements. The formation of enhanced-quality mixed SAMs was investigated as a function of the molecular composition of the thiol mixture and the proportion of ethanol/water solvent used during thei…
Parameters Analysis Influencing 3D Measurement without Contact by Laser Scanner to Make a Compensation Model
2005
International audience; The 3D measurement is more and more important in industrial applications. There are different applications like 3D inspection or reverse engineering. In the both cases, the classical techniques by contact present the advantage of a good accuracy but the costs are expensive because of the slow progress of the measurement. In an other hand, the without contact technologies have a high cadency of points measurement but with a lower accuracy. We present in this study a methodology to estimate the measurement uncertainties and to correct the systematic error. The global error can be separated in random error (in the order of 25 m for the considered laser scanner) and in …
Elaboration et caractérisation d’une structure composite (sable et déchets plastiques recyclés) : Amélioration de la résistance par des charges en ar…
2018
This project aims at conceiving(designing) one paves with plastic waste got back in the discharges and with mixture of sand and gravel. This pavement that must be of use to the realization of pavements and public highways, must thus be capable of answering the technical conditions of its use. However, the fabrication method and the used material(equipment) must be rather simple to allow its fast handling by little qualified workers and a low(weak) production cost to be economically competitive. Pavements will thus be tested to identify their performance at the same time mechanical and physical then used on life-size to understand(include) their ageing because of their wear. Finally, an equi…
Multi-physical analysis of the electrochemical behaviour of OFHC copper surfaces obtained by orthogonal cutting
2020
International audience; As mechanical, physical, and microstructural properties of metals can be significantly affected by the machining process, electrochemical properties and corrosion resistance are consequently altered. Manufacturers should control the impact of cutting conditions on surface integrity, as it will affect the component’s functional performance and life. This study addresses the case of orthogonal cutting of oxygen-free high conductivity (OFHC) copper. A set of experiments was performed and a statistical analysis was conducted to reveal the relationship between the cutting conditions and the surface integrity in terms of residualstresses, microstructure, plastic deformatio…