Search results for "FS"
showing 10 items of 1992 documents
Friction stir welding of stainless steel thin sheets in lap configuration
2013
New research trends for Friction Stir Welding include the use of highly resistant materials as steels and titanium alloys. In the paper a continuum based FEM model for Friction Stir Welding of lap joint made out of thin stainless steel sheets is proposed, that is 3D Lagrangian implicit, coupled, rigid-viscoplastic. The model, whose potential has been analyzed though temperature distribution comparisons, is able to predict temperature, strain and strain rate distributions, with varying process variables. In this way the FEM model can be applied for effective process and tool design.
In Vitro–In Vivo Fluctuation Spectroscopies
2010
Fluorescence correlation spectroscopy (FCS) was first developed for biophysical studies in analogy with photon scattering correlation spectroscopy. Although it is mainly devoted to the study of freely diffusing particles, FCS is actually able to discern between different kinds of motions, such as diffusion, anomalous diffusion, or drift motions. The frontier application of FCS nowadays is in medical studies both within cells and on the cell membranes, and in the investigation of single molecules in solid matrices. In this field, FCS originated also image correlation spectroscopy methods. The whole field can be unified under the name of fluorescence fluctuation spectroscopy (FFS). We present…
Forming of aluminum foam sandwich panels: Numerical simulations and experimental tests
2006
Abstract The forming of the completed aluminium foam sandwich (AFS) panels would determine an improvement in the manufacturing of parts and panels. In this paper the authors have investigated the formability of AFS through experiments and numerical simulations. As far as the former are concerned, commercially prepared panels have been considered and bending and stamping processes have been taken into account. In addition, FEM analyses have been developed, utilizing a porous material model following the evolution of the material density throughout the forming processes.
Wear Analysis During Friction Stir Processing of A359+20%SiC MMC
2009
Metal Matrix Composites (MMC) are very interesting materials for applications in the automotive and aerospace fields, since they combine the lightness of Aluminium with the strength of the ceramic reinforcement. These materials are very difficult to join and conventional welding techniques are not applicable, whereas solid-state welding techniques, like Friction Stir Welding (FSW), could be a solution. However very hard tool materials will need to be chosen in order to overcome the problem of heavy abrasive tool wear. In this work the wear behaviour of coated and uncoated steel tools has been investigated in the Friction Stir Processing of extruded bars in A359 + 20%SiC. AISI 1040 steel was…
Charge-transfer interactions between fullerenes and a mesoporous tetrathiafulvalene-based metal–organic framework
2019
The design of metal–organic frameworks (MOFs) incorporating electroactive guest molecules in the pores has become a subject of great interest in order to obtain additional electrical functionalities within the framework while maintaining porosity. Understanding the charge-transfer (CT) process between the framework and the guest molecules is a crucial step towards the design of new electroactive MOFs. Herein, we present the encapsulation of fullerenes (C60) in a mesoporous tetrathiafulvalene (TTF)-based MOF. The CT process between the electron-acceptor C60 guest and the electron-donor TTF ligand is studied in detail by means of different spectroscopic techniques and density functional theor…
Ab initio molecular dynamics simulations of negative thermal expansion in ScF3: the effect of the supercell size
2020
The authors sincerely thank S. Ali, A. Kalinko, and F. Rocca for providing experimental EXAFS data, as well as M. Isupova, V. Kashcheyevs, and A. I. Popov for stimulating discussions. Financial support provided by project No. 1.1.1.2/VIAA/l/16/147 (1.1.1.2/16/I/001) under the activity “Post-doctoral research aid” realized at the Institute of Solid State Physics, University of Latvia is greatly acknowledged by D.B. A.K and J.P. would like to thank the support of the Latvian Council of Science project No. lzp-2018/2–0353.
Synchrotron Radiation and Chemistry: Studies of Materials for Renewable Energy Sources
2014
We present an overview of selected applications of synchrotron radiation methods to topical chemical research. The analysis is limited to the studies on materials for renewable energy sources, focussing on topics peculiar to chemical research, such as reactivity and synthesis routes; in particular, the paper takes into account subjects having some relevance for the production and storage of energy based on hydrogen. Hydrogen production and storage are taken into account in the sections concerning: (i) Dye-sensitized solar cells, (ii) Metal-organic frameworks and (iii) Hydrides for hydrogen storage; production of energy by fuel cell devices is treated in (iv) Oxide ion and proton conductors …
Dopants and defects: local structure and dynamics in barium cerates and zirconates
2010
In this paper we present an overview of state-of-the-art EXAFS measurements and data analysis on Ba, Ce, Zr, Y, In and Gd local environments in Y:BaCeO3, In:BaCeO3, Gd:BaCeO3, Y:BaZrO3, and In:BaZrO3, at different temperatures, hydration degrees and doping levels. This approach allows to reach unprecedented insights on the peculiar role of the dopant, and its interactions with the other lattice defects. In particular, we evidence that each different dopant shows unique behavior, depending mainly on its electronic structure, and that the usual criterion of ionic radius matching is not useful to outline an effective doping strategy of proton-conducting perovskites. As what concerns the struct…
From ZIF-8@Al2O3Composites to Self-Supported ZIF-8 One-Dimensional Superstructures
2015
International audience; Efficient preparation of composite materials consisting of ZIF-8 nanocrystals embedded inside the channels of macroporous anodic aluminum oxide membranes is reported. 1-D self-supported ZIF-8 superstructures are recovered through matrix dissolution.
Evidence for a Double Doping Regime in Nd:YAG nanopowders
2009
Nanopowders of Yttrium Aluminium Garnet doped with neodymium (Nd:YAG) were investigated by X-Ray Absorption Fine Structure (XAFS) at the Nd LIII-edge in the 1.3 - 20.8 % doping range. XANES spectra appear similar in the full range of the Nd concentration. However, a significant decrease in the white line intensity of XANES is revealed as the quantity of Nd doping ions increases. Plotting the white line intensity as a function of Nd doping ions reveals two linear trends with two different slopes, identifying a threshold value where the neodymium concentration reaches 5 at.% This experimental finding provides support for the existence of a double doping regime in Nd:YAG nanopowders.