Grenoble Institute of Technology

About: Grenoble Institute of Technology is a education organization based out in Grenoble, France. It is known for research contribution in the topics: Hyperspectral imaging & Geology. The organization has 3427 authors who have published 5345 publications receiving 137158 citations. The organization is also known as: Grenoble INP.

Characterization of fluctuations in granular hopper flow

Abstract: We present a 2D discrete modelling of sand flow through a hopper using realistic grain shapes. A post-processing method is used to assess the local fluctuations in terms of void ratio, coordination number, velocity magnitude, and mean stress. The characteristics of fluctuations associated with the four considered quantities along the vertical axis of the hopper and across the entire hopper are carefully examined. The flow fluctuations for coordination number, velocity magnitude and mean stress are all found to take the form of radial waves originating from the lower centre of the hopper and propagating in the opposite direction of the granular flow. Quantitative characteristics of these waves (shape, amplitude, frequency, velocity, etc.) are identified. The fluctuations in void ratio however are not supportive of the observation of density waves in the granular flow as mentioned in some experiments. The possible reasons for this apparent contradiction are discussed, as well as possible extensions of this work.

Investigation of Forming, SET, and Data Retention of Conductive-Bridge Random-Access Memory for Stack Optimization

Abstract: In this paper, we investigate in depth Forming, SET, and Retention of conductive-bridge random-access memory (CBRAM). A kinetic Monte Carlo model of the CBRAM has been developed considering ionic hopping and chemical reaction dynamics. Based on inputs from ab initio calculations and the physical properties of the materials, the model offers the simulation of both the Forming/SET and the Data Retention operations. It aims to create a bond between the physics at atomic level and the device behavior. From the model and experimental results obtained on decananometric devices, we propose an understanding of the physical mechanisms involved in the CBRAM operations. Using the consistent Forming/SET and Data Retention model, we obtained good agreement with the experimental data. Finally, the impact of each layer of the CBRAM on the Forming/SET behavior is decorrelated, allowing an optimization of the performance.

Coupling between phonons and magnetic excitations in orthorhombic Eu 1 − x Y x MnO 3

Abstract: In this work we present a detailed study of the structural and lattice-dynamic properties of Y-doped ${\text{EuMnO}}_{3}$ ceramics (${\text{Eu}}_{1\ensuremath{-}x}{\text{Y}}_{x}{\text{MnO}}_{3}$ with $0\ensuremath{\le}x\ensuremath{\le}0.5$). A thorough analysis toward the correlation between both structural and Raman modes parameters has been undertaken. Our results provide evidence for two main structural distortions of ${\text{MnO}}_{6}$ octahedra, arising from a cooperative Jahn-Teller and rotational distortions in these compounds. The temperature dependence of the ${\text{B}}_{1\text{g}}$ symmetric stretching mode of the ${\text{MnO}}_{6}$ units has revealed either a positive or negative shift regarding the pure anharmonic temperature dependence of the phonon frequency, which strongly depends on the Y concentration. This frequency renormalization is explained in terms of a competition between ferromagnetic and antiferromagnetic interactions. Frequency shifts observed well above the N\'eel temperature are likely associated with the coupling between phonons and electromagnons, which provides further grounds for the existence of strong spin-phonon coupling in this compound. Both polar and magnetoelectric properties ascertained for $x=0.2$ provide clear evidence of the central role played by spin-phonon coupling in yielding the physical behavior of the Y-doped ${\text{EuMnO}}_{3}$ system.

Investigation of the Sintering of Heterogeneous Powder Systems by Synchrotron Microtomography and Discrete Element Simulation

Abstract: Collective particle behavior such as interparticle coordination and particle rearrangement plays a significant role in the sintering of heterogeneous powder systems. Those phenomena have been investigated by in situ X-ray microtomography and discrete element simulation (DEM). In situ 3D images of sintering copper-based systems have been obtained at the European Synchrotron Research Facilities. The sintered systems comprise a dense packing of atomized copper powder with a size range of 0–63 μm and the same powder including artificial pores. Quantitative analysis of these images provided valuable data on local strain, coordination number, and particle movement. The sintering of the same systems has been simulated with the discrete element code dp3D. From this set of information, the importance of collective behavior on densification and microstructural evolution is assessed and the relevance of DEM to describe it is discussed.

Nanocomposites of PBAT and cellulose nanocrystals modified by “in situ” polymerization and melt extrusion

Abstract: Cellulose nanocrystals (CNC) were successfully grafted with a low molecular weight poly(butylene glutarate) through an “in situ” polymerization procedure. The grafting treatment decreased the CNC hydrophilic character and increased the onset of their thermal degradation by approximately 20°C, thus increasing the possibilities of CNC application. Composites of grafted and nongrafted CNC with a poly(butylene-adipate-co-terephthalate) (PBAT) matrix were prepared by melt extrusion. The CNC addition led to an increase of 50% of the tensile elastic modulus of the PBAT. In addition, dynamic mechanical thermal analysis showed that the composite with CNC retained its high modulus even at temperatures far above the glass transition temperature of PBAT. At 60°C the storage modulus of the composite with CNC was approximately 200% higher than that of the pure PBAT. Thus, in this work, nanocomposites of improved properties were obtained through a combination of “in situ” polymerization and melt extrusion. POLYM. ENG. SCI., 2016. © 2016 Society of Plastics Engineers