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排序方式: 共有68条查询结果,搜索用时 15 毫秒
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Andreas Wüstefeld Götz Bokelmann Christophe Zaroli Guilhem Barruol 《Computers & Geosciences》2008,34(5):515-528
We present a graphical user interface to facilitate the processing of teleseismic shear-wave splitting observations. In contrast to a fully automated technique, we present a manual, per-event approach that maintains user control during the sequence of processing. The SplitLab environment is intended to undertake the repetitive processing steps while enabling the user to focus on quality control and eventually the interpretation of the results. Pre-processing modules of SplitLab create a database of events and link the corresponding seismogram files. The seismogram viewer tool uses this database to perform the measurement interactively. Post-processing of the combined results of such a project includes a viewer and export option. Our emphasis lies in the application to teleseismic shear-wave splitting analysis, but our code can be extended easily for other purposes. SplitLab can be downloaded at http://www.gm.univ-montp2.fr/splitting/. 相似文献
3.
This work presents a study of non-premixed flames at supercritical-pressure conditions. Emphasis is placed on flame stability in liquid rocket engines fueled with liquid oxygen and gaseous hydrogen. The flame structure sensitivity to strain, pressure, temperature and real-fluid effects was investigated in detailed opposed-jet flames calculations. It is shown that the flame is very robust to strain, that the flamelet assumption is valid for the conditions of interest, and that real-fluid phenomena can have a significant impact on flame topology. At high-pressure supercritical conditions, small pressure or temperature variations can induce strong changes of thermodynamic properties across the flame. A substantial finding was also that the presence of water from combustion significantly increases the critical pressure of the mixture, but this does not lead to a saturated state where two-phase flow may be observed. The present study then shows that a single-phase real-fluid approach is relevant for supercritical hydrogen–oxygen combustion. Resultant observations are used to develop a flamelet model framework that combines detailed real-fluid thermodynamics with a tabulated chemistry approach. The governing equation for energy contains a compressible source term that models the flame. Through this approach, the solver is capable of capturing compressibility and strain-rate effects. Good agreements have been obtained with respect to detailed computations. Heat release sensitivity to strain and pressure variations is also recovered. Consequently, this approach can be used to study combustion stability in actual burners. The approach preserves the density gradient in the high-shear region between the liquid-oxygen jet and product rich flame region. The latter is a key requirement to properly simulate dense-fluid jet destabilization and mixing in practical devices. 相似文献
4.
Agnès Princivalle Guilhem MartinCéline Viazzi Christian GuizardNicolas Grunbaum Laurent Dessemond 《Journal of power sources》2011,196(22):9238-9245
Ceramic powders of BaCe0.9Y0.1O2.95 (BCY10) have been prepared by the sol-gel method. Barium and yttrium acetate and cerium nitrate were used as ceramic precursors in a water solution. The reaction process studied by DTA-TG and XRD showed that calcination of the precursor powder at T ≥ 1000 °C produces a single perovskite phase. The densification behaviour of green compacts studied by constant heating rate dilatometry revealed that the shrinkage rate was maximal at 1430 °C. Sintered densities higher than 95% of the theoretical one were thus obtained below 1500 °C. The bulk and additional blocking effects were characterized by impedance spectroscopy in wet atmosphere between 150 and 600 °C. A proton conduction behaviour was clearly identified. The blocking effect can be related to a space-charge depletion layer of protons in the vicinity of grain boundaries. 相似文献
5.
Adaptive speciation has been much debated in recent years, with a strong emphasis on how competition can lead to the diversification of ecological and sexual traits. Surprisingly, little attention has been paid to this evolutionary process to explain intrahost diversification of parasites. We expanded the theory of competitive speciation to look at the effect of key features of the parasite lifestyle, namely fragmentation, aggregation and virulence, on the conditions and rate of sympatric speciation under the standard ‘pleiotropic scenario’. The conditions for competitive speciation were found similar to those for non-parasite species, but not the rate of diversification. Adaptive evolution proceeds faster in highly fragmented parasite populations and for weakly aggregated and virulent parasites. Combining these theoretical results with standard empirical allometric relationships, we showed that parasite diversification can be faster in host species of intermediate body mass. The increase in parasite load with body mass, indeed, fuels evolution by increasing mutants production, but because of the deleterious effect of virulence, it simultaneously weakens selection for resource specialization. Those two antagonistic effects lead to optimal parasite burden and host body mass for diversification. Data on the diversity of fishes'' gills parasites were found consistent with the existence of such optimum. 相似文献
6.
Guilhem Arrachart David J. Cassidy Inna Karatchevtseva Gerry Triani 《Journal of the American Ceramic Society》2009,92(9):2109-2115
Titanium ethoxide [Ti(OEt)4 ] was modified with aminobenzoic acid (AB) or aminosalicylic acid (AS) in order to control the hydrolysis and condensation rates, and to allow the preparation of organic–inorganic hybrid materials. A suite of complementary techniques, including Fourier transform infrared spectroscopy, NMR, SEM, thermogravimetric analysis, and X-ray diffraction, were used to elucidate the effects of incorporating an organic functional group into the precursor chemistry and its subsequent affect on the structure and morphology of the resultant hybrid material. The annealing behavior of the resulting hybrid titanium base materials was also investigated. Our studies show that both amino acid organic ligands, AB and AS, chemically bounded to the titanium complex, effect the precursor reactivity, specifically the hydrolysis and polycondensation reactions, which control the evolution and formation of the nanohybrid-based titania material. Following sol–gel processing, the nanohybrid materials are amorphous, due to the incorporation of the organic component. The phase transition (amorphous–anatase–rutile) observed during annealing from 25° to 800°C show subtle differences in the crystallization behavior, which are associated with the nature of the organic ligand. 相似文献
7.
Albert Tarancón Alejandro Morata Guilhem Dezanneau Stephen J. Skinner John A. Kilner Sònia Estradé F. Hernández-Ramírez F. Peiró J.R. Morante 《Journal of power sources》2007
GdBaCo2O5+x (GBCO) was evaluated as a cathode for intermediate-temperature solid oxide fuel cells. A porous layer of GBCO was deposited on an anode-supported fuel cell consisting of a 15 μm thick electrolyte of yttria-stabilized zirconia (YSZ) prepared by dense screen-printing and a Ni–YSZ cermet as an anode (Ni–YSZ/YSZ/GBCO). Values of power density of 150 mW cm−2 at 700 °C and ca. 250 mW cm−2 at 800 °C are reported for this standard configuration using 5% of H2 in nitrogen as fuel. An intermediate porous layer of YSZ was introduced between the electrolyte and the cathode improving the performance of the cell. Values for power density of 300 mW cm−2 at 700 °C and ca. 500 mW cm−2 at 800 °C in this configuration were achieved. 相似文献
8.
Hamid Demmou Sarhane Khalfaoui Edwige Guilhem Robert Valette 《Reliability Engineering & System Safety》2004,84(1):33
This paper deals with safety in design of mechatronic systems. We propose a method based on a qualitative analysis of a Petri net model of the system. It allows deriving feared scenarios by determining the sequences of actions and state changes leading to the feared state in which the passenger's safety is no longer guaranteed. The Petri net model of the system takes into account normal behaviour, failures and reconfiguration mechanisms. Our approach uses linear logic as formal framework and is based on a backward and a forward reasoning. It derives feared scenarios as causal relationships between normal states and the feared one. 相似文献
9.
The diffusional properties of molecules in solution vary dramatically upon addition of a solid chromatographic phase. This effect can be monitored via pulsed-gradient spin-echo NMR used in conjunction with moderately fast rotation of the sample (high-resolution magic angle spinning) to produce exploitable spectra. The molecular diffusion coefficients observed in this condition are averages reflecting the equilibrium population distribution among the different phases. It is thus possible to use this information for investigating a crucial step of reversed-phase chromatography, namely, the partitioning of the analyte between different phases. In this work, we describe the evolution of the apparent diffusion coefficient of typical solutes for water/acetonitrile solvent mixtures of varying proportions. 相似文献
10.
Angelika E. Neitzel Guilhem X. De Hoe Matthew V. Tirrell 《Current Opinion in Solid State & Materials Science》2021,25(2):100897
Charged (macro)molecules are essential components in natural materials and organisms; thus the rational design of biomimetic materials requires a holistic understanding of structure–property relationships in charged systems. We discuss recent progress in uncovering such relationships for polyzwitterions and polyelectrolyte complexes, with emphases on the synthetic strategies that were employed in systematic studies. For polyelectrolytes, discussion is confined to the effects that structural variations in polycation and polyanion structure have on the fundamental phase behavior of the corresponding polyelectrolyte complexes. In the field of polyzwitterions, both fundamental and applied properties are discussed in relation to chemical structure. Finally, we present an overview of promising chemistries that will expand the structural landscape of charged macromolecules with the aim of stimulating new research to further uncover and understand the fundamental design principles for these materials. 相似文献