Modelling of the radiative properties of an opaque porous ceramic layer

Solid Oxide Fuel Cells (SOFCs) operate at temperatures above 1,100 K where radiation effects can be significant. Therefore, an accurate thermal model of an SOFC requires the inclusion of the contribution of thermal radiation. This implies that the thermal radiative properties of the oxide ceramics used in the design of SOFCs must be known. However, little information can be found in the literature concerning their operating temperatures. On the other hand, several types of ceramics with different chemical compositions and microstructures for designing efficient cells are now being tested. This is a situation where the use of a numerical tool making possible the prediction of the thermal radiative properties of SOFC materials, whatever their chemical composition and microstructure are, may be a decisive help. Using this method, first attempts to predict the radiative properties of a lanthanum nickelate porous layer deposited onto an yttria stabilized zirconium substrate can be reported

Publishing on the WEB

Publishing on the Web is a complex activity for which the knowledge of the HTML language is only a very basic prerequisite. Web publishers have to compose good HTML documents that satisfy a number of constraints imposed by the WWW media. They must then interlink these documents to build webs with good readability and maintainability properties. During this process, publishers have to use and sometimes to program software tools, ranging from editors and converters to sophisticated documentation systems. A tour of the web publishing tasks is presented. At each stage, guidelines and automated tools are proposed, that may contribute to build webs of good quality

Evaluation of an urban NMHC emission inventory by measurements and impact on CTM results

This paper presents an evaluation of the consistency of an urban state-of-the-art hydrocarbon (HC) emission inventory. The evaluation was conducted through the comparison of this inventory with hourly HC measurements during two summer months in the centre of Marseille, on the Mediterranean French coast. Factors of under or overestimation could be calculated for each compound on the basis of a systematic HC to HC ratio analysis. These results, associated with a deep analysis of the speciation profiles, show that most of the common and highly concentrated hydrocarbons (such as butanes) are too much predominant in the emission speciation, while the heavy and less common species (branched alkanes, substituted aromatics) are under-represented in the inventory. The urban diffuse sources appear here as one critical point of the inventories. The disagreements were shown to have a strong incidence on the representation of the air mass reactivity. In a last step, the identified uncertainties in emissions were implemented in an air-quality model for sensitivity studies. It was shown that the observed biases in the inventory could affect the regional ozone production, with a probable impact on ozone peaks of 2-10 ppbv over the area. © 2010 Elsevier Ltd

Flash ionization of the partially ionized wind of the progenitor of SN 1987A

The H II region created by the progenitor of SN 1987A was further heated and ionized by the supernova flash. Prior to the flash, the temperature of the gas was 4000 - 5000 K, and helium was neutral, while the post-flash temperature was only slightly less than 10^5 K, with the gas being ionized to helium-like ionization stages of C, N and O. We have followed the slow post-flash cooling and recombination of the gas, as well as its line emission, and find that the strongest lines are N V 1240 and O VI 1034. Both these lines are good probes for the density of the gas, and suitable instruments to detect the lines are STIS on HST and FUSE, respectively. Other lines which may be detectable are N IV] 1486 and [O III] 5007, though they are expected to be substantially weaker. The relative strength of the oxygen lines is found to be a good tracer of the color temperature of the supernova flash. From previous observations, we put limits on the hydrogen density, n_H, of the H II region. The early N V 1240 flux measured by IUE gives an upper limit which is n_H ~ 180 \eta^{-0.40} cm^{-3}, where \eta is the filling factor of the gas. The recently reported emission in [O III] 5007 at 2500 days requires n_H = (160\pm12) \eta^{-0.19} cm^{-3}, for a supernova burst similar to that in the 500full1 model of Ensman & Burrows (1992). For the more energetic 500full2 burst the density is n_H = (215\pm15) \eta^{-0.19} cm^{-3}. These values are much higher than in models of the X-ray emission from the supernova (n_H ~ 75 cm^{-3}), and it seems plausible that the observed [O III] emission is produced primarily elsewhere than in the H II region. We also discuss the type of progenitor consistent with the H II region. In particular, it seems unlikely that its spectral type was much earlier than B2 Ia.Comment: LaTeX, 23 pages including 4 figures. To appear in ApJ (Main Journal

Effects of water activity (aw) on the growth of some epiphytic micro-organisms isolated from grape berry

It is well known that wet weather often induces microbial deterioration of grape berries by Botrytis cinevea during the noble rot process, and that heavy rainfall increases the number of epiphytic micro-organisms. To better understand the influence of environmental conditions, we investigated the effects of water availabilty on the in vitro growth of 7 yeast strains, 10 strains of bacteria and one strain of the fungus Botrytis cinerea, isolated from grape berries. The results confirm that growth of Botrytis cinerea is inhibited at water activities (aw) < 0.93. Growth was highest if sucrose was added to the medium compared to other solutes (KCl, CaCl2), Most bacteria were more sensitive to water deficit than Botrytis cinerea. Bacteria were only able to grow at aw, ranging from 0.997 to 0.940. Yeasts were more resistant than bacteria. Most yeasts grow at aw between 0.96 and 0.88, The present results may contribute to control epiphytic micro-organisms in over-ripened fruit of grapevine.

Two-photon Rabi-Hubbard and Jaynes-Cummings-Hubbard models: photon pair superradiance, Mott insulator and normal phases

We study the ground state phase diagrams of two-photon Dicke, the one-dimensional Jaynes-Cummings-Hubbard (JCH), and Rabi-Hubbard (RH) models using mean field, perturbation, quantum Monte Carlo (QMC), and density matrix renormalization group (DMRG) methods. We first compare mean field predictions for the phase diagram of the Dicke model with exact QMC results and find excellent agreement. The phase diagram of the JCH model is then shown to exhibit a single Mott insulator lobe with two excitons per site, a superfluid (SF, superradiant) phase and a large region of instability where the Hamiltonian becomes unbounded. Unlike the one-photon model, there are no higher Mott lobes. Also unlike the one-photon case, the SF phases above and below the Mott are surprisingly different: Below the Mott, the SF is that of photon {\it pairs} as opposed to above the Mott where it is SF of simple photons. The mean field phase diagram of the RH model predicts a transition from a normal to a superradiant phase but none is found with QMC.Comment: 14 pages, 14 figure

THE EFFECTS OF IMPACT AVOIDANCE TECHNIQUES ON HEAD INJURY RISK

The purpose of this study was to determine the influence of impact deflection and neck compliance on peak linear and peak angular accelerations during a front impact to a Hybrid III head using a pneumatic linear impactor. Impact deflection was done by translating the headform laterally and showed to be effective at reducing linear and angular accelerations as well as GSI. Neck compliance was altered using one Hybrid III 50th percentile neck and two modified Hybrid III necks. A less compliant neck increased linear acceleration but decreased angular acceleration. When compared to estimated injury thresholds, the results demonstrated that an increase in lateral translation or a decrease in neck compliance resulted in a significant decrease in the risk of head injury as reflected by peak linear and angular accelerations