1,352 research outputs found
Concurrent Specification of Embedded Systems: An Insight into the Flexibility vs Correctness Trade-Off
Diseases & disorder
Is Small Perfect? Size Limit to Defect Formation in Pyramidal Pt Nanocontacts
We report high resolution transmission electron microscopy and ab initio
calculation results for the defect formation in Pt nanocontacts (NCs). Our
results show that there is a size limit to the existence of twins (extended
structural defects). Defects are always present but blocked away from the tip
axes. The twins may act as scattering plane, influencing contact electron
transmission for Pt NC at room temperature and Ag/Au NC at low temperature.Comment: 4 pages, 3 figure
Surface Effects on the Mechanical Elongation of AuCu Nanowires: De-alloying and the Formation of Mixed Suspended Atomic Chains
We report here an atomistic study of the mechanical deformation of AuxCu(1-x)
atomic-size wires (NWs) by means of high resolution transmission electron
microscopy (HRTEM) experiments. Molecular dynamics simulations were also
carried out in order to obtain deeper insights on the dynamical properties of
stretched NWs. The mechanical properties are significantly dependent on the
chemical composition that evolves in time at the junction; some structures
exhibit a remarkable de-alloying behavior. Also, our results represent the
first experimental realization of mixed linear atomic chains (LACs) among
transition and noble metals; in particular, surface energies induce chemical
gradients on NW surfaces that can be exploited to control the relative LAC
compositions (different number of gold and copper atoms). The implications of
these results for nanocatalysis and spin transport of one-atom-thick metal
wires are addressed.Comment: Accepted to Journal of Applied Physics (JAP
Size Limit Of Defect Formation In Pyramidal Pt Nanocontacts.
We report high resolution transmission electron microscopy and ab initio calculation results for defect formation in sharp pyramidal Pt nanocontacts. Our results show that there is a size limit to the existence of twins (extended structural defects). These defects are always present but blocked away from the tip axes. They may act as scattering planes, influencing the electron conductance for Pt nanocontacts at room temperature and Ag/Au nanocontacts at low temperature (<150 K).9925550
recent advances in spline couplings reliability
Abstract Spline couplings are mechanical components widely used to transmit torque between rotating parts. Although they are well known components, critical issues such as wear damage and un haven loads affect them especially when working in misaligned conditions. Wear damage appears on engaging teeth bringing to component failures. The main way to reduce wear damage is to lubricate the engaging teeth or to apply surface coatings. In this work wear damage on spline coupling was investigated and a compound made of grease added with graphene has been tested against standard lubricants in order to find out if it may improve the wear strength of these components. Experimental tests were performed by means of both standard testing machine provided by a particular testing device and dedicated test rig, designed to perform tests with misaligned spline couplings. Preliminary results show that the presence of graphene improves the grease performance, reducing the coefficient of friction (bringing to a reduction of uneven overloads and wear)
- …