Search results for "characterization"
showing 10 items of 1054 documents
NO formation tendency characterization for solid fuels in fluidized beds
2013
Abstract Usually the standard fuel analysis is not enough to allow for accurate NO emission predictions in large scale fluidized bed combustion. This paper presents NO formation tendency characterization results from novel laboratory measurements in a small-scale fluidized bed combustor. With the special two-stage oxidation method it is possible to eliminate the observed problems of unstable test conditions during rapid pyrolysis of high-volatile fuels in batch combustion. Experimental results of the conversion of fuel nitrogen to NO are presented for wide range of fuels, ranging from coal-type fuels to peat, biomasses and wastes. A NO formation tendency database is formed based on the resu…
Caractérisation des tôles Fer-Silicium en régime dynamique pulsant
1992
Using a characterization method based on the Epstein's frame principle, we study the evolution of the magnetic and losses characteristics of NO Fe-Si sheets with respect to the fundamental frequency, the temperature and the wave front under time-variable sinusoidal or constant wave front trapezoidal magnetic flux density. At last, we modelise the evolution of the iron losses with respect to these parameters, except the temperature
Modeling a non-stationary bots’ arrival process at an e-commerce Web site
2017
Abstract The paper concerns the issue of modeling and generating a representative Web workload for Web server performance evaluation through simulation experiments. Web traffic analysis has been done from two decades, usually based on Web server log data. However, while the character of the overall Web traffic has been extensively studied and modeled, relatively few studies have been devoted to the analysis of Web traffic generated by Internet robots (Web bots). Moreover, the overwhelming majority of studies concern the traffic on non e-commerce websites. In this paper we address the problem of modeling a realistic arrival process of bots’ requests on an e-commerce Web server. Based on real…
Meeting Apart: Woody Allen's Characters, Films and Spectators
2007
An analysis of the relationships between Woody Allen's films (from "Take the Money and Run", 1969, to "Anything Else", 2003) and their spectators, starting frim a definition of the public image of the filmmaker then focusing on the film persona and the way the films represent authorial figures and the paradoxical meeting between film and spectator(s).
PrVO$_4$ under High Pressure: Effects on Structural, Optical and Electrical Properties
2020
In pursue of a systematic characterization of rare-earth vanadates under compression, in this work we present a multifaceted study of the phase behavior of zircon-type orthovanadate PrVO$_4$ under high pressure conditions, up until 24 GPa. We have found that PrVO$_4$ undergoes a zircon to monazite transition at around 6 GPa, confirming previous results found by Raman experiments. A second transition takes place above 14 GPa, to a BaWO$_4$-I--type structure. The zircon to monazite structural sequence is an irreversible first-order transition, accompanied by a volume collapse of about 9.6%. Monazite phase is thus a metastable polymorph of PrVO$_4$. The monazite-BaWO$_4$-II transition is found…
Effect of mechanical stirring and temperature on dynamic hydrothermal synthesis of titanate nanotubes
2017
Abstract In the late century, it has been clearly demonstrated that titanate nanotubes (TNTs) are attractive nanomaterials with various potential applications due to their interesting properties. In this work, an essential reaction parameter, rarely considered in the literature, has been studied: stirring during hydrothermal synthesis. For this purpose, an intermittent mechanical stirring, ranging from 0 to 20 min/h, has been applied during the TNTs synthesis using a new dynamic hydrothermal reactor. It was proved that a long stirring cycle (more than 10 min/h) at 150 °C and an overall reaction time of 16 h promotes nanoribbons synthesis instead of nanotubes. In this context, a detailed mor…
Complex tribomechanical characterization of ZnO nanowires: nanomanipulations supported by FEM simulations
2016
In the present work, we demonstrate a novel approach to nanotribological measurements based on the bending manipulation of hexagonal ZnO nanowires (NWs) in an adjustable half-suspended configuration inside a scanning electron microscope. A pick-and-place manipulation technique was used to control the length of the adhered part of each suspended NW. Static and kinetic friction were found by a 'self-sensing' approach based on the strain profile of the elastically bent NW during manipulation and its Young's modulus, which was separately measured in a three-point bending test with an atomic force microscope. The calculation of static friction from the most bent state was completely reconsidered…
Structure and Dynamics of the Quasi-Liquid Layer at the Surface of Ice from Molecular Simulations
2018
We characterized the structural and dynamical properties of the quasi-liquid layer (QLL) at the surface of ice by molecular dynamics simulations with a thermodynamically consistent water model. Our simulations show that for three low-index ice surfaces only the outermost molecular layer presents short-range and mid-range disorder and is diffusive. The onset temperature for normal diffusion is much higher than the glass temperature of supercooled water, although the diffusivity of the QLL is higher than that of bulk water at the corresponding temperature. The underlying subsurface layers impose an ordered template, which produces a regular patterning of the ice/water interface at any tempera…
Filters for X-Ray Detectors on Space Missions
2022
Thin filters and gas-tight windows are used in space to protect sensitive X-ray detectors from out-of-band electromagnetic radiation, low-energy particles, and molecular contamination. Though very thin and made of light materials, filters are not fully transparent to X-rays. For this reason, they ultimately define the detector quantum efficiency at low energies. In this chapter, we initially provide a brief overview of filter materials and specific designs adopted on space experiments with main focus on detectors operating at the focal plane of grazing incidence X-ray telescopes. We then provide a series of inputs driving the design and development of filters for high-energy astrophysics sp…
Structural Characterization of Molecular Interface Layers Using Neutron and X-Ray Reflectivity Techniques
1992
Synthetic microstructures used in biological research today include a variety of different systems that serve very diverse purposes and require very different fabrication and characterization techniques. One class of microstructures that is at the boundary between life and materials sciences, and certainly has been associated closer to the latter in the past, is that of molecularly structured planar interface films. In fact, Langmuir-Blodgett (LB) films,1 i.e. molecularly layered films comprised of amphiphatic organic molecules on solid substrates, have been used for many years as model systems for the investigation of molecular interactions between chromophores or donor/ acceptor couples, …