Search results for "Note"
showing 10 items of 10709 documents
Friction stir consolidation of aluminum machining chips
2017
Friction stir consolidation (FSC) is a solid-phase manufacturing process that consolidates metal powder, chips, or scraps into solid blocks via severe plastic deformation and solid state welding. It has the potential to be a more economical and âgreenâ process to recycle metal waste. In this study, solid discs were made from AA6061 aluminum alloy machining chips by FSC. The progression of the process was revealed by analyzing the motion of the tool, consolidating force, power history, and macro/microstructure of discs produced from a series of partial consolidation experiments. A bowl-shaped recrystallized zone in the vertical cross-sections of the disc products was observed and conside…
Time-resolved buildup of twisted indirect exchange interaction in two-dimensional systems
2019
We study theoretically the time-domain dynamics of the spin-dependent Ruderman-Kittel-Kasuya-Yosida (RKKY) interaction between driven magnetic impurities localized in a spin-orbit-coupled two-dimensional system. Particular attention is given to the influence of the spin-orbit coupling (SOC) on the system's dynamical response to a time-dependent precessional motion of the localized magnetic moment. We show that, via the RKKY mechanism, a flip of the spin $z$ component of one localized moment affects all $x,\phantom{\rule{4pt}{0ex}}y$, and $z$ spin components of the other localized moment. The Friedel oscillations and the transient spin current triggered by the time-varying localized spin dep…
Methanol fuel processor and PEM fuel cell modeling for mobile application
2010
International audience; The use of hydrocarbon fed fuel cell systems including a fuel processor can be an entry market for this emerging technology avoiding the problem of hydrogen infrastructure. This article presents a 1 kW low temperature PEM fuel cell system with fuel processor, the system is fueled by a mixture of methanol and water that is converted into hydrogen rich gas using a steam reformer. A complete system model including a fluidic fuel processor model containing evaporation, steam reformer, hydrogen filter, combustion, as well as a multi-domain fuel cell model is introduced. Experiments are performed with an IDATECH FCS1200™ fuel cell system. The results of modeling and experi…
Efficient Modeling of NMR Parameters in Carbon Nanosystems
2015
Rapid growth of nanoscience and nanotechnology requires new and more powerful modeling tools. Efficient theoretical modeling of large molecular systems at the ab initio and Density Functional Theory (DFT) levels of theory depends critically on the size and completeness of the basis set used. The recently designed variants of STO-3G basis set (STO-3Gel, STO-3Gmag), modified to correctly predict electronic and magnetic properties were tested on simple models of pristine and functionalized carbon nanotube (CNT) systems and fullerenes using the B3LYP and VSXC density functionals. Predicted geometries, vibrational properties, and HOMO/LUMO gaps of the model systems, calculated with typical 6-31G…
Study of the electrochemical and optical properties of fullerene and methano[60]fullerenediphosphonate derivatives in solution and as self-assembled …
2014
Four methanofullerenes with phosphonate groups attached to a C60 core were synthesized to probe their electrochemical and optical properties both in solution and as self-assembled monolayer structures (SAMs). As the methano[60]fullerenediphosphonate is a water soluble derivative of the fullerene it has high potential as an imaging molecule in biological applications and in optoelectronics. For the processing of fullerene based SAMs different electrode substrates (ITO, Au and Si) with specific anchoring groups (zirconium, cysteamine and amino-silane) were used. The formation of the C60-SAMs to the surfaces were investigated by atomic force microscopy (AFM), infrared spectroscopy, contact ang…
Efficient and accurate modeling of electron photoemission in nanostructures with TDDFT
2017
We derive and extend the time-dependent surface-flux method introduced in [L. Tao, A. Scrinzi, New J. Phys. 14, 013021 (2012)] within a time-dependent density-functional theory (TDDFT) formalism and use it to calculate photoelectron spectra and angular distributions of atoms and molecules when excited by laser pulses. We present other, existing computational TDDFT methods that are suitable for the calculation of electron emission in compact spatial regions, and compare their results. We illustrate the performance of the new method by simulating strong-field ionization of C60 fullerene and discuss final state effects in the orbital reconstruction of planar organic molecules.
Organic fractal nano-dimensional structures based on fullerene C60
2019
The ways for a synthesis of nanoporous and close-packed types of fullerene C60 aggregates in two-component organic solvents (toluene + tetrahydrofuran) were established as well as their structural ...
Effect of packing on the cluster nature of C nanotubes: An information entropy analysis
2007
The possibility of the existence of single-wall carbon nanotubes (SWNTs) in organic solvents in the form of clusters is discussed. A theory is developed based on a bundlet model for clusters, which enables describing the distribution function of clusters by size. Comparison of the calculated values of solubility with experiments would permit obtaining energetic parameters characterizing the interaction of an SWNT with its surrounding, in a solid or solution. Fullerenes and SWNTs are unique objects, whose behaviour in many physical situations is characterized by remarkable peculiarities. Peculiarities in solutions show up first in that fullerenes and SWNTs represent the only soluble forms of…
Interface engineering in efficient vacuum deposited perovskite solar cells
2016
Abstract We studied the effect of the charge transport layers in p-i-n perovskite solar cells using vacuum deposited methylammonium lead iodide thin-film absorbers. While solution-processed perovskite films are frequently deposited directly on PEDOT:PSS leading to good solar cell performances, in some cases even to very good Voc values, we show that in devices employing vacuum deposited MAPbI3 perovskites, the removal of the polyTPD electron blocker substantially reduces the photovoltaic behavior. This is indicative of rather different charge transport properties in the vacuum deposited MAPbI3 perovskites compared to those prepared from solution. On the other hand, we investigated the use o…
Correlation of epoxy material properties with the toughening effect of fullerene-like WS2 nanoparticles
2016
Abstract This work deals with the toughening effect of inorganic, fullerene-like WS2 (IF-WS2) nanoparticles (NPs) on epoxy. It has been hypothesized that this toughening effect depends on the epoxy’s cross-link density, its molecular defect fraction or its reference fracture toughness K Ic . Seven different epoxy systems were filled with 0.5% laboratory-made IF-WS2 NPs by mass and investigated in order to analyze which material properties are determining the toughening effect. These NPs were similar to commercially available IF-WS2 NPs, but their agglomerates could not be broken up as successfully and they yielded less toughening effect. The cross-link density of the epoxies measured via dy…