Search results for "electronics"

Environment assisted photoconversion of luminescent surface defects in SiO 2 nanoparticles

2017

Abstract Time-resolved photoluminescence investigation on SiO 2 nanoparticles was carried out in controlled atmosphere, with the aim to discern the effects induced on the typical blue luminescence band by high power UV Nd:YAG laser photons (4.66 eV) and by some selected molecular species of the air (O 2 , N 2 , CO 2 , H 2 O). These factors ultimately determine both the brightness and photostability of the emitting defect, so as to limit the unique and attracting potentialities offered by this system in many applicative fields. Here it is highlighted that the effects due to photons and molecules, singularly considered, are not additive, the radiation being more dramatic in reducing the emiss…

Impact of Convectively Detrained Ice Crystals on the Humidity of the Tropical Tropopause Layer in Boreal Winter

2020

Deep convection detraining in the uppermost tropical troposphere is capable of transporting water vapor and ice into the tropical tropopause layer (TTL), but the impact of deep convection on the global and regional TTL water vapor budget remains uncertain. In particular, the role of convectively detrained ice crystals that remain suspended after active convection has subsided is not well understood. These ice crystals represent aging cirrus anvils detached from the convective core. We use a cloud microphysical model that tracks individual ice crystals throughout their lifetimes to quantify the impact of detrained ice on the humidity of the TTL during boreal winter. Convective influence of a…

The dynamics of tropospheric aerosols

1966

After a brief review of the present knowledge of the Stratospheric sulfate layer, several possible mechanisms of formation are discussed in detail. A direct transport of low tropospheric particles into the stratosphere by convective clouds penetrating the tropopause is not very likely because these penetrations are not high enough and because of the chemical composition of the stratospheric particles. DOI: 10.1111/j.2153-3490.1966.tb00286.x

Modeling of Melt Flow and Heat Transfer in Stationary Gas Tungsten Arc Welding with Vertical and Tilted Torches

2021

A 3D numerical simulation was conducted to study the transient development of temperature distribution in stationary gas tungsten arc welding with filler wire. Heat transfer to the filler wire and the workpiece was investigated with vertical (90°) and titled (70°) torches. Heat flux, current flux, and gas drag force were calculated from the steady-state simulation of the arc. The temperature in the filler wire was determined at three different time intervals: 0.12 s, 0.24 s, and 0.36 s. The filler wire was assumed not to deform during this short time, and was therefore simulated as solid. The temperature in the workpiece was calculated at the same intervals using heat flux, current flux, ga…

Probing of nanocontacts inside a transmission electron microscope

2007

In the past twenty years, powerful tools such as atomic force microscopy have made it possible to accurately investigate the phenomena of friction and wear, down to the nanometer scale. Readers of this book will become familiar with the concepts and techniques of nanotribology, explained by an international team of scientists and engineers, actively involved and with long experience in this field. Edited by two pioneers in the field, 'Fundamentals of Frictions and Wear at the Nanoscale' is suitable both as first introduction to this fascinating subject, and also as a reference for researchers wishing to improve their knowledge of nanotribology and to keep up with the latest results in this …

Dopant Contrast in Semiconductors as Interpretation Challenge at Imaging by Electrons

2007

Mechanisms responsible for the contrast between differently doped areas in semiconductors, which is observed in electron micrographs, is discussed as regards the key factors determining the sign and magnitude of the contrast. Experimental data obtained by means of the scanning electron microscope (SEM), scanning low energy electron microscope and photoelectron emission microscope are reviewed together with hints following from them for compilation of a model of the contrast mechanism.

1996

The uses of atomic force microscopy, scanning tunneling microscopy, electron spectroscopic imaging, electron energy loss spectroscopy and low voltage, high resolution scanning electron microscopy in polymer research are reviewed

Reliable Propagation of Magnetic Domain Walls in Cross Structures for Advanced Multiturn Sensors

2017

[EN] We develop and analyze an advanced concept for a domain-wall-based sensing of rotations. Moving domain walls in n closed loops with n - 1 intersecting convolutions by rotating fields, we are able to sense n rotations. By combining loops with coprime numbers of rotations, we create a sensor system allowing for the total counting of millions of turns of a rotating applied magnetic field. We analyze the operation of the sensor and identify the intersecting cross structures as the critical component for reliable operation. Specifically, depending on the orientation of the applied field angle with the magnetization in the branches of the cross, a domain wall is found to propagate in an unwa…

Smart camera based on an Embedded HW/SW Co-Processor

2008

Abstract This paper describes an image acquisition and a processing system based on a new coprocessor architecture designed for CMOS sensor imaging. The system exploits the full potential CMOS selective access imaging technology because the coprocessor unit is integrated into the image acquisition loop. The acquisition and coprocessing architecture are compatible with the majority of CMOS sensors. It enables the dynamic selection of a wide variety of acquisition modes as well as the reconfiguration and implementation of high-performance image preprocessing algorithms (calibration, filtering, denoising, binarization, pattern recognition). Furthermore, the processing and data transfer, from t…

Electro-optic dynamics in thermally poled Ge core doped silica fibre

2003

The electro-optic (EO) dynamics of a twin hole germania core doped fibre when an applied electric field at elevated temperature modifies the symmetry of glass is reported. An EO peak was recorded after 10 min poling. The results were interpreted with a two-space charge model.