ParisTech

About: ParisTech is a education organization based out in Paris, France. It is known for research contribution in the topics: Residual stress & Finite element method. The organization has 1888 authors who have published 1965 publications receiving 55532 citations. The organization is also known as: Paris Institute of Technology & ParisTech Développement.

Method of test for burning velocity measurement of flammable gases and results

Abstract: This article describes a test method for measuring the burning velocity of flammable gases with air used as oxidant. Burning velocity is a physical property enabling the classification of flammable refrigerants. A safety standard committee, such as ASHRAE 34 SSPC, requests information about methods of tests capable of improving the classification of flammable refrigerants. The burning velocity is a function of the flammable gas concentration in the total mixture with air, and it can be measured at concentrations ranging from the lower propagation limit (LPL) of the flame in the tube to the upper propagation limit (UPL). The burning velocity reaches a maximum in the vicinity of the stoichiometric concentration. The test method is based on the initiation of the combustion of the gas, or blends of gases, in a homogenous mixture with air contained in a vertical cylindrical tube, and the observation and the recording of the flame propagation. Results for R-290, R-152a, R-717, R-32, and R-143a are presented using the tube method as described and performed at the Center for Energy and Processes.

Nanocavitation around a crack tip in a soft nanocomposite: A scanning microbeam small angle X‐ray scattering study

Abstract: We explore nanocavitation around the crack tip region in a styrene-butadiene random copolymer filled with typical carbon black (CB) particles used in the rubber industry for toughening the rubber. Using quasistatic loading conditions and a highly collimated X-ray microbeam scanned around the crack tip, we demonstrate the existence of a damage zone consisting of nanovoids in a filled elastomer matrix. The existence of voids near the crack tip is demonstrated by a significant increase of the scattering invariant Q/Q0 in front of both fatigued and fresh cracks. The size of the zone where cavities are present critically depends on the macroscopic strain em, the loading history, and the maximum energy release rate G applied to accommodate the crack. Our findings show that nanovoiding occurs before fracture in typical CB-filled elastomers and that realistic crack propagation models for such elastomers should take into account a certain level of compressibility near the crack tip. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2015, 53, 422–429

Self-assembly of (S)-glutamic acid on Ag(100): a combined LT-STM and ab initio investigation.

Abstract: Self-assembly of organic molecules at metal surfaces is of greatest importance in nanoscience; in fact, it opens new perspectives in the field of molecular electronics and in the study of biocompatible materials. Combining an experimental low-temperature scanning tunneling microscopy investigation with ab initio calculations, we succeeded to describe in detail (S)-glutamic acid adsorption on Ag(100) at T = 350 K. We find that (S)-glutamic acid organizes in a squared structure and, at variance with the majority of cases reported in literature, it adsorbs in the neutral form, 4.6 A above the surface plane. The interaction with the poorly reactive Ag substrate is only due to weak van der Waals forces, while H-bonds between carboxyl groups and the formation of a OCOH−OCOH−OCOH−OCOH cycle at the vertex of the squares are the main responsible for the self-assembly.