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101.
Sai Hung CheungTodd A. Oliver Ernesto E. Prudencio Serge PrudhommeRobert D. Moser 《Reliability Engineering & System Safety》2011,96(9):1137-1149
In this paper, we apply Bayesian uncertainty quantification techniques to the processes of calibrating complex mathematical models and predicting quantities of interest (QoI's) with such models. These techniques also enable the systematic comparison of competing model classes. The processes of calibration and comparison constitute the building blocks of a larger validation process, the goal of which is to accept or reject a given mathematical model for the prediction of a particular QoI for a particular scenario. In this work, we take the first step in this process by applying the methodology to the analysis of the Spalart-Allmaras turbulence model in the context of incompressible, boundary layer flows. Three competing model classes based on the Spalart-Allmaras model are formulated, calibrated against experimental data, and used to issue a prediction with quantified uncertainty. The model classes are compared in terms of their posterior probabilities and their prediction of QoI's. The model posterior probability represents the relative plausibility of a model class given the data. Thus, it incorporates the model's ability to fit experimental observations. Alternatively, comparing models using the predicted QoI connects the process to the needs of decision makers that use the results of the model. We show that by using both the model plausibility and predicted QoI, one has the opportunity to reject some model classes after calibration, before subjecting the remaining classes to additional validation challenges. 相似文献
102.
Salima Alem Ta-Ya Chu Shing C. Tse Salem Wakim Jianping Lu Raluca Movileanu Ye Tao Francis Bélanger Denis Désilets Serge Beaupré Mario Leclerc Sheila Rodman David Waller Russell Gaudiana 《Organic Electronics》2011,12(11):1788-1793
We investigated the effect of solvents on the morphology, charge transport and device performance of poly[N-9″-hepta-decanyl-2,7-carbazole-alt-5,5-(4′,7′-di-2-thienyl-2′,1′,3′-benzothiadiazole)] (PCDTBT) and [6,6]-phenyl C71-butyric acid methyl ester (PC70BM) based solar cells. To carry out this investigation, chloroform and 1,2-dichlorobenzene were chosen as good solvents of the two compounds. Films prepared with chloroform exhibit larger domains than those prepared with 1,2-dichlorobenzene and their size increases with the amount of PC70BM. Fine tuning of the domain size was realized by using a solvent of mixed chloroform and 1,2-dichlorobenzene. At a mixing ratio of 50%:50%, a power conversion efficiency of 6.1% was achieved on PCDTBT:PC70BM (1:3) devices with an active area of 1 cm2, under air mass 1.5 global (AM 1.5 G) irradiation at 100 mW/cm2. 相似文献
103.
Gachot G Ribière P Mathiron D Grugeon S Armand M Leriche JB Pilard S Laruelle S 《Analytical chemistry》2011,83(2):478-485
To allow electric vehicles to be powered by Li-ion batteries, scientists must understand further their aging processes in view to extend their cycle life and safety. For this purpose, we focused on the development of analytical techniques aiming at identifying organic species resulting from the degradation of carbonate-based electrolytes (EC-DMC/LiPF(6)) at low potential. As ESI-HRMS provided insightful information to the mechanism and chronological formation of ethylene oxide oligomers, we implemented "gas" GC/MS experiments to explore the lower mass range corresponding to highly volatile compounds. With the help of chemical simulation tests, we were able to discriminate their formation pathways (thermal and/or electrochemical) and found that most of the degradation compounds originate from the electrochemically driven linear alkyl carbonate reduction upon cycling and to a lesser extent from a two-step EC reduction. Deduced from these results, we propose an overall electrolyte degradation scheme spanning the entire mass range and the chemical or electrochemical type of processes. 相似文献
104.
This study was aimed at investigating which processes cause acidic herbicides (e.g., bentazone, MCPA and dichlorprop) to rapidly disappear in the lagoons of the Rhône delta, which are peculiar brackish and shallow aquatic environments. The use of the model MASAS (Modeling of Anthropogenic Substances in Aquatic Systems) revealed that sorption, sedimentation, volatilization, flushing and abiotic hydrolysis had a minor role in the attenuation of the investigated herbicides. Laboratory scale biodegradation and photodegradation studies were conducted to better assess the significance of these two processes in the natural attenuation of herbicides in brackish (lagoons) waters with respect to fresh waters (canals draining paddy fields). Herbicide biodegradation rates were significantly lower in lagoon water than in canal water. Consequently, photodegradation was the main dissipation route of all investigated herbicides. The contribution of indirect photolysis was relevant for MCPA and dichlorprop while direct photolysis dominated for bentazone removal. There is a need to further investigate the identity of phototransformation products of herbicides in lagoons. 相似文献
105.
Marusczak N Larose C Dommergue A Paquet S Beaulne JS Maury-Brachet R Lucotte M Nedjai R Ferrari CP 《The Science of the total environment》2011,409(10):1909-1915
Total mercury (THg) and methylmercury (MeHg) concentrations were measured in the muscle of Arctic charr (Salvelinus alpinus) and in the water column of 4 lakes that are located in the French Alps. Watershed characteristics were determined (6 coverage classes) for each lake in order to evaluate the influence of watershed composition on mercury and methylmercury concentrations in fish muscle and in the water column. THg and MeHg concentrations in surface water were relatively low and similar among lakes and watershed characteristics play a major role in determining water column Hg and MeHg levels. THg muscle concentrations for fish with either a standardized length of 220 mm, a standardized age of 5 years or for individualuals did not exceed the 0.5 mg kg− 1 fish consumption advisory limit established for Hg by the World Health Organization (WHO, 1990). These relatively low THg concentrations can be explained by watershed characteristics, which lead to short Hg residence time in the water column, and also by the short trophic chain that is characteristic of mountain lakes. Growth rate did not seem to influence THg concentrations in fish muscles of these lakes and we observed no relationship between fish Hg concentrations and altitude. This study shows that in the French Alps, high altitude lakes have relatively low THg and MeHg concentrations in both the water column and in Arctic charr populations. Therefore, Hg does not appear to present a danger for local populations and the fishermen of these lakes. 相似文献
106.
Serge K. Katenev 《Journal of Infrared, Millimeter and Terahertz Waves》1995,16(10):1825-1835
Analytical expressions for EM-waves and evolutionary equations for the waves in geometric regular waveguides with layered nonstationary media are presented. A piecewise-homogeneous and periodic along the guide's axis medium is considered in detail. The analytical solution of the dispersion equation is invariant to both the guide's cross-section contour form and eigenwave type. The periodicity dispersion, particular resonances and an algorythm of the modeling application are discussed. 相似文献
107.
108.
Erik H. Saenger Oliver S. Krüger Serge A. Shapiro 《International Journal of Fracture》2006,139(3-4):569-576
We present a new technique for static computations of effective elastic properties of multiple fractured rocks. This approach
is based on the viscoelastic rotated staggered finite-difference (FD) grid wave propagation technique. Our simulations are
used to explain discrepancies of some recent numerical studies. The focus is on scale effects of a so-called representative
volume element (RVE). From the point of view of classical micromechanics we review different numerical techniques: Static
as well as dynamic numerical experiments. We show that the differential effective medium theory (DEM) is capable of producing
satisfactory predictions of effective elastic moduli. For non-dilute crack densities this is not the case for the non-interacting
approximation (NIA). 相似文献
109.
110.
Nicolas Boutheiller Pierre Jarry Eric Kerherv Jean‐Marie Pham Serge Vigneron 《国际射频与微波计算机辅助工程杂志》2003,13(6):429-437
This article describes a basic building block for microwave waveguide filters. It uses a new coupling scheme where all resonant modes are used at their cutoff frequency. It is composed of a cascade of basic nonloaded rectangular cavities where the modes are alternately single mode and dual mode. These cavities are coupled directly, without any iris. Neither coupling nor tuning screws are needed. The analysis of the discontinuities is performed by the method of moments (MoM). The synthesis makes use of an optimization method based on the genetic algorithm. Prototypes have been realized and measurements are shown to confirm the analysis results. © 2003 Wiley Periodicals, Inc. Int J RF and Microwave CAE 13: 429–437, 2003. 相似文献