Search results for "Position"
showing 10 items of 6771 documents
Confident methods for the evaluation of the hydrogen content in nanoporous carbon microfibers
2012
Abstract Nanoporous carbon microfibers were grown by chemical vapor deposition in the vapor-liquid solid mode using different fluid hydrocarbons as precursors in different proportions. The as-grown samples were further treated in argon and hydrogen atmospheres at different pressure conditions and annealed at several temperatures in order to deduce the best conditions for the incorporation and re-incorporation of hydrogen into the microfibers through the nanopores. Since there are some discrepancies in the results on the hydrogen content obtained under vacuum conditions, in this work, we have measured the hydrogen content in the microfibers using several analytical methods in ambient conditi…
Modeling And Measurements Of The Arc Plasma In A Mixture Of Gases
2006
Radial distributions of Ar mass fractions and temperatures in plasmas produced in a wall-stabilized arc have been calculated. Modeling have been performed for many different mixtures of Ar+N2 and three different arc currents. The obtained results show that the radial distributions of Ar mass fractions strongly depend on the chemical composition of the plasma. In plasmas containing large amount of Ar the distributions have local minima at the arc axis (in high temperature plasma regions), whereas in plasmas consisting mainly of nitrogen the distributions reveal maxima on the discharge axis. Those features seem to be connected with the dissociation of the nitrogen.
A new approach to the growth of ZnO by vapour transport
2005
The crystal growth of ZnO by vapour transport is classically made in presence of additional species which enhance the growth process. Usually, additional species have been considered as chemical transport agents that promote a typical CVT (Chemical Vapour Transport) process. Recently, we have proposed a new interpretation of the chemical role of some of these species. This new interpretation considers that, in some cases, the additional species promote a partial consumption of the O2 provided by the ZnO decomposition and, consequently, a Zn excess is generated. This excess of Zn pressure activates the ZnO decomposition and the growth rate is enhanced. Among those species, carbon shows an ad…
Composition et cognition musicales : création, perception, appréciation
2005
Ce texte est un rapport de fin de recherche issu de l'ACI cognitique.; Ce projet avait pour objet d'apporter des éléments objectifs de réflexion sur les possibilités et limites de la perception et de la compréhension des matériaux et des structures d'une oeuvre de musique contemporaine. Les buts spécifiques comprenaient l'étude : 1) des processus d'invention et de résolution de problèmes dans la composition musicale, 2) des processus de traitement perceptif et de mémorisation des matériaux musicaux, 3) du traitement perceptif et mnésique des variations ou transformations opérées sur ces matériaux et de l'intégration des matériaux et de leurs transformations dans une forme d'ensemble, 4) du …
European society of hypertension position paper on ambulatory blood pressure monitoring
2013
Ambulatory blood pressure monitoring (ABPM) is being used increasingly in both clinical practice and hypertension research. Although there are many guidelines that emphasize the indications for ABPM, there is no comprehensive guideline dealing with all aspects of the technique. It was agreed at a consensus meeting on ABPM in Milan in 2011 that the 34 attendees should prepare a comprehensive position paper on the scientific evidence for ABPM.This position paper considers the historical background, the advantages and limitations of ABPM, the threshold levels for practice, and the cost-effectiveness of the technique. It examines the need for selecting an appropriate device, the accuracy of dev…
The role of contact chemoreception in the host location process of an egg parasitoid
2016
Taste allows insects to detect palatable or toxic foods, identify a mate, and select appropriate oviposition sites. The gustatory system strongly contributes to the survival and reproductive success of many species, yet it is rarely studied in insect parasitoids. In order to locate and assess a host in which they will lay their eggs, female wasps actively search for chemical cues using their sensory organs present mainly on the antennae. In this paper, we studied the role of antennal taste sensilla chaetica in the perception of contact semiochemicals in Trissolcus brochymenae (Hymenoptera: Platygastridae), an egg parasitoid of the brassicaceae pest Murgantia histrionica (Heteroptera: Pentat…
Modelling and Analysis of Nonstationary Vehicle-to-Infrastructure Channels with Time-Variant Angles of Arrival
2018
In mobile radio channel modelling, it is generally assumed that the angles of arrival (AOAs) are independent of time. This assumption does not in general agree with real-world channels in which the AOAs vary with the position of a moving receiver. In this paper, we first present a mathematical model for the time-variant AOAs. This model serves as the basis for the development of two nonstationary multipath fading channels models for vehicle-to-infrastructure communications. The statistical properties of both channel models are analysed with emphasis on the time-dependent autocorrelation function (ACF), time-dependent mean Doppler shift, time-dependent Doppler spread, and the Wigner-Ville sp…
Chemical and Microbiological Characterization for PDO Labelling of Typical East Piedmont (Italy) Salami
2015
This study is focused on the characterisation of typical salami produced in Alessandria province (North West of Italy). Seventeen small or medium salami producers from this area were involved in the study and provided the samples investigated. The aim is double and consists in obtaining a screening of the characteristics of different products and following their evolution along ripening. The study involved five types of typical salami that were characterised for aroma components and nutritional features. This approach could provide a basis for a possible PDO or PGI label request. Principal Component Analysis and cluster analysis were used as multivariate statistical tools for data treatment…
Questions in Cognitive Mimetics
2021
Human thinking advances through questions and answers. Any field of human endeavor is permeated by the presence of questions, answers and presuppositions. Questions have a kind of universality, whereby one can place the question marks on anything, including questions themselves. The process of asking the right questions about the right things and in the right way are key for the explication of an approach. Recently, we have begun thinking about an approach to the design of intelligent technology: Cognitive mimetics. In brief, the idea is to take inspiration of empirical human thinking in specific contexts to develop AI solutions. The purpose of this article is to question this approach from…
Modelling and prediction of retention in high-performance liquid chromatography by using neural networks
1995
Multi-layer feed-forward neural networks trained with an error back-propagation algorithm have been used to model retention behaviour of liquid chromatography as a function of the composition of the mobile phases. Conventional hydro-organic and micellar mobile phases were considered. Accurate retention modelling and prediction have been achieved using mobile phases defined by two, three and four parameters. With micellar mobile phases, the parameters involved included the concentrations of surfactant and organic modifier, pH and temperature. It is shown that neural networks provide a competitive tool to model varied inherent nonlinear relationships of retention behaviour with respect to the…