2,089 research outputs found
Total and dissociative photoionization cross sections of N2 from threshold to 107 eV
The absolute cross sections for the production of N(+) and N2(+) were measured from the dissociative ionization threshold of 115 A. In addition, the absolute photoabsorption and photoionization cross sections were tabulated between 114 and 796 A. The ionization efficiencies were also given at several discrete wave lengths between 660 and 790 A. The production of N(+) fragment ions are discussed in terms of the doubly excited N2(+) states with binding energies in the range of 24 to 44 eV
10th international conference on gas-liquid and gas-liquid-solid reactor engineering preface
Following the success of the nine previous conferences on GasâLiquid and GasâLiquidâSolid reactor Engineering which were held at Columbus, OH, USA (1992), Cambridge, UK (1995), Kanagawa, Japan (1997), Delft, The Netherlands (1999), Melbourne, Australia (2001), Vancouver, Canada (2003), Strasbourg, France (2005), New Delhi, India (2007) and Montreal, Canada (2009) the tenth conference with the same theme is being held in Braga, Portugal, from 26 to 29 June 2011. This conference will cover all aspects of multiphase reactors related to progress made in the understanding, performance and operation of these reactors and will bring together scientists and engineers from universities and industry.
The involvement of top researchers in GasâLiquid and GasâLiquidâSolid Reactor Engineering, the high quality of the papers presented and the line of continuity that has been guaranteed by the leadership of Prof. L.S. Fan of Ohio State University and the other members of the International Scientific Committee has made GLS a leading conference in Chemical Engineering. GLS has been held at regular intervals, every two years and in order to attract professionals across the globe, the venue of the GLS conference is shifted in a thoughtful manner amongst the continents. This conference has become an important meeting point for the exchange of views among scientists and engineers in one of the most important and complex issues in chemical engineering science and practice.
The organizing committee is very pleased to be associated with Elsevier to have, as in most of the previous GLS editions, the proceedings of GLS10 published in Chemical Engineering Science (CES). As a result of a strict peer review process aiming at keeping with the highest standards of the journal, the GLS10 CES special issue includes a total of 39 papers, selected from the 150 Abstracts that were submitted to GLS10.
Our sincere acknowledgments are due to Professor Anton P.J. Middelberg, the Executive Editor of CES, for his cooperation throughout the reviewing process. Also, we would like to express our gratitude to all the reviewers that made possible a timely publication of this special issue. Thanks are due to Genevieve Green from Elsevier for the excellent management of this special issue publication.
Finally, it is our pleasure to dedicate this GLS10 CES special issue to Professor John Davidson as a tribute to his pioneering work and extraordinary contributions to GasâLiquid and GasâLiquidâSolid Reactor Engineering and to Chemical Engineering
Persistent currents in coupled mesoscopic rings
We have analysed the nature of persistent currents in open coupled mesoscopic
rings. Our system is comprised of two ideal loops connected to an electron
reservoir. We have obtained analytical expressions for the persistent current
densities in two rings in the presence of a magnetic field. We show that the
known even-odd parity effects in isolated single loops have to be generalised
for the case of coupled rings. We also show that when the two rings have
unequal circumferences, it is possible to observe opposite currents
(diamagnetic or paramagnetic) in the two rings for a given Fermi level.Comment: Submitted to PRB. 9 figures availabel on reques
Bubbles in viscous liquids: Time dependent behaviour and wake characteristics
The dynamics of a bubble, initially stationary and spherical, rising in a viscous Newtonian liquid have been studied numerically using 3-D Volume-of-Fluid (VOF) method implemented in the Gerris flow solver. The study encompasses 8.7â€Eo (=ÎÏgD2/ÏÎÏgD2/Ï)â€641 and Reâ€151. Additionally, results published in the literature encompassing bubbles with lower values of Eo numbers were also considered, such that the overall dependencies of bubble shape, wake characteristics, and drag coefficient over a large range of Eo and Re values can be identified. While it was found that the deformation of the bubbles as predicted through the numerical study can generally replicate experimental observations presented, several limitations were identified, such as in the representation of skirt formation behind a skirted bubble and the formation of satellite bubbles behind a bubble rising at high Reynolds numbers. The dependency of the bubble aspect ratio on the Weber and Morton numbers was confirmed for cases of spherical and ellipsoidal bubbles; whilst for spherical cap and skirted bubbles the aspect ratio was found to depend largely on the Reynolds and Capillary numbers, respectively. Finally, the expansion and formation of closed/open laminar wakes behind the rising bubble were analysed and was found to correlate well with the bubble Re and Eo numbers
Aharonov-Bohm oscillations and spin transport in a mesoscopic ring with a magnetic impurity
We present a detailed analysis of the Aharonov-Bohm (AB) interference
oscillations manifested through transmission of an electron in a mesoscopic
ring with a magnetic impurity atom inserted in one of its arms. The spin
polarization transport is also studied. The electron interacts with the
impurity through the exchange interaction leading to exchange spin-flip
scattering. Transmission in the spin-flipped and spin-unflipped channels are
explicitly calculated. We show that the entanglement between electron and
spin-flipper states lead to a reduction of AB oscillations in spite of absence
of any inelastic scattering. The spin-conductance (related to spin-polarized
transmission coefficient) is asymmetric in the flux reversal as opposed to the
two probe conductance which is symmetric under flux reversal. We point out
certain limitations of this model in regard to the general notion of dephasing
in quantum mechanics.Comment: 6 pages RevTeX, 9 eps figures included, enlarged version of
cond-mat/000741
Biodiesel production from camelina oil: Present status and future perspectives
Camelina sativa (L.) Crantz is an oilseed crop with favorable potentials for biodiesel production, such as the high plant yield, high oil content in the seed, high net energy ratio, and low oil production cost. This review paper deals with the present state and perspectives of biodiesel production from camelina oil. First, important issues of camelina seed pretreatment and biodiesel production are reviewed. Emphasis is given to different biodiesel technologies that have been used so far worldwide, the economic assessment of the camelina oil biodiesel (COB) production, the camelina-based biorefineries for the integrated biodiesel production, the COB life cycle analysis, and impact human health and ecosystem. Finally, the perspectives of COB production from the techno-economic and especially genetic engineering points of view are discussed
Hydrodynamic Simulation of Cyclone Separators
Cyclone separators are commonly used for separating dispersed solid particles from gas phase. These devices have simple construction; are relatively inexpensive to fabricate and operate with moderate pressure losses. Therefore, they are widely used in many engineering processes such as dryers, reactors, advanced coal utilization such as pressurized and circulating fluidized bed combustion and particularly for removal of catalyst from gases in petroleum refinery such as in fluid catalytic cracker (FCC). Despite its simple operation, the fluid dynamics and flow structures in a cyclone separator are very complex. The driving force for particle separation in a cyclone separator is the strong swirling turbulent flow. The gas and the solid particles enter through a tangential inlet at the upper part of the cyclone. The tangential inlet produces a swirling motion of gas, which pushes the particles to the cyclone wall and then both phases swirl down over the cyclone wall. The solid particles leave the cyclone through a duct at the base of the apex of the inverted cone while the gas swirls upward in the middle of the cone and leaves the cyclone from the vortex finder. The swirling motion provides a centrifugal force to the particles while turbulence disperses the particles in the gas phase which increases the possibility of the particle entrainment. Therefore, the performance of a cyclone separator is determined by the turbulence characteristics and particle-particle interaction.Full Tex
Physical routes for the synthesis of kesterite
This paper provides an overview of the physical vapor technologies used to synthesize Cu2ZnSn(S,Se)4
thin films as absorber layers for photovoltaic applications. Through the years, CZT(S,Se) thin films
have been fabricated using sequential stacking or co-sputtering of precursors as well as using
sequential or co-evaporation of elemental sources, leading to high-efficient solar cells. In addition,
pulsed laser deposition of composite targets and monograin growth by the molten salt method were
developed as alternative methods for kesterite layers deposition. This review presents the growing
increase of the kesterite-based solar cell efficiencies achieved over the recent years. A historical
description of the main issues limiting this efficiency and of the experimental pathways designed to
prevent or limit these issues is provided and discussed as well. Afinal section is dedicated to the
description of promising process steps aiming at further improvements of solar cell efficiency, such as
alkali doping and bandgap grading1. R Caballero and M LeĂłn acknowledge financial support via the Spanish Ministry of Science, Innovation and Universities project (WINCOST, ENE2016-80788-C5-2-R) and thank H2020 EU Programme under the project INFINITE-CELL (H2020-MSCA-RISE-2017-777968).
2. S Canulescu and J Schou acknowledge the support from Innovation Fund Denmark.
3. D-H Kim acknowledges financial support via the DGIST R&D Program of the Ministry of Science and ICT, KOREA (18-BD-05).
4.C. Malerba acknowledges the support from the Italian Ministry of Economic development in the framework of the Operating Agreement with ENEA for the Research on the Electric System.
5.A Redinger acknowledges financial support via the FNR Attract program, Project : SUNSPOT, Nr.11244141.
6. E Saucedo thanks H2020 EU Programme under the projects STARCELL (H2020-NMBP-03-2016-720907) and INFINITE-CELL (H2020-MSCA-RISE-2017-777968), the Spanish Ministry of Science, Innovation and Universities for the IGNITE project (ENE2017-87671-C3-1-R), and the European Regional Development Funds (ERDF, FEDER Programa Competitivitat de Catalunya 2007â2013). IREC belong to
the SEMS (Solar Energy Materials and Systems) Consolidated Research Group of the âGeneralitat de Catalunyaâ (Ref. 2017 SGR 862).
7. Taltech acknowledges financial support via the Estonian Ministry of Education and Research funding project IUT19-28 and the European Union Regional Development Fund, Project TK141.
8. B Vermang has received funding from the European Research Council (ERC) under the European Unionâs Horizon 2020 Research and Innovation Programme (Grant Agreement No 715027
Carrier induced ferromagnetism in diluted magnetic semi-conductors
We present a theory for carrier induced ferromagnetism in diluted magnetic
semi-conductor (DMS). Our approach treats on equal footing quantum fluctuations
within the RPA approximation and disorder within CPA. This method allows for
the calculation of , magnetization and magnon spectrum as a function of
hole, impurity concentration and temperature. It is shown that, sufficiently
close to , and within our decoupling scheme (Tyablicov type) the CPA for
the itinerant electron gas reduces to the Virtual Crystal Approximation. This
allows, in the low impurity concentration and low density of carriers to
provide analytical expression for . For illustration, we consider the case
of and compare our results with available experimental data.Comment: 5 figures included. to appear in Phys. Rev. B (brief report
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