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61.
Francisco Payri Jose Vicente Pastor Raul Payri Julien Manin 《Journal of Mechanical Science and Technology》2011,25(1):209-219
The optical depth is responsible of limiting the optical diagnostic using visible wavelength in the sprays. This paper proposes
to measure the optical depth directly in a real Diesel spray through line-of-sight laser extinction measurements. This easily
reproducible method which does not require expensive or complex optical techniques is detailed and the measurement procedure
is presented in this paper. As diesel sprays are mostly optically thick, the measurements in the denser region are not reliable
and a fuel concentration model has been used to derive the results to the entire spray. This work provides values of SMD at
different distance from the nozzle tip depending on the specific parameters like injection pressure or discharge density.
The values extracted from a combined experimental/computational approach have been compared to PDPA measurements under the
same testing conditions. The results have shown that the maximum optical depth was higher than 10 and that an increase of
the injection pressure led to higher τ values. The SMD values appeared to be below the results measured by the PDPA and the
droplet diameter showed to be the main responsible of the optical depth of the jet under the tested conditions. 相似文献
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65.
M.L. TrudeauD. Laul R. VeilletteA.M. Serventi A. MaugerC.M. Julien K. Zaghib 《Journal of power sources》2011,196(18):7383-7394
In situ high-resolution transmission electron microscopy (HRTEM) studies of the structural transformations that occur during the synthesis of carbon-coated LiFePO4 (C-LiFePO4) and heat treatment to elevated temperatures were conducted in two different electron microscopes. Both microscopes have sample holders that are capable of heating up to 1500 °C, with one working under high vacuum and the other capable of operating with the sample surrounded by a low gaseous environment. The C-LiFePO4 samples were prepared using three different compositions of precursor materials with Fe(0), Fe(II) or Fe(III), a Li-containing salt and a polyethylene-block-poly(ethylene glycol)-50% ethylene oxide or lactose. The in situ TEM studies suggest that low-cost Fe(0) and a low-cost carbon-containing compound such as lactose are very attractive precursors for mass production of C-LiFePO4, and that 700 °C is the optimum synthesis temperature. At temperatures higher than 800 °C, LiFePO4 has a tendency to decompose. The same in situ measurements have been made on particles without carbon coat. The results show that the homogeneous deposit of the carbon deposit at 700 °C is the result of the annealing that cures the disorder of the surface layer of bare LiFePO4. Electrochemical tests supported the conclusion that the C-LiFePO4 derived from Fe(0) is the most attractive for mass production. 相似文献
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A method for the screening of multiple attribute decision-making problems is presented. The model assists the decision-maker in eliminating inferior alternatives and insignificant attributes prior to a detailed evaluation. A preliminary evaluation of the alternatives provides the information necessary for the reduction of the decision problem. The procedure calculates maximum preference factors on which the decision-maker can base his screening decisions. These factors assess the role of alternatives in the final ranking by estimating their potential to become superior to other alternatives. Since screening tasks are carried out early in decision-making, the information available is generally uncertain. Uncertainty is represented in the model using fuzzy sets. This framework permits the handling of both imprecise and precise (crisp) estimates of impacts and provides a possibil-istic assessment of the risk associated with screening decisions. 相似文献
68.
An optimized explicit low-storage fourth-order Runge–Kutta algorithm is proposed in the present work for time integration. Dispersion and dissipation of the scheme are minimized in the Fourier space over a large range of frequencies for linear operators while enforcing a wide stability range. The scheme remains of order four with nonlinear operators thanks to the low-storage algorithm. Linear and nonlinear propagation problems are finally solved to illustrate the accuracy of the present Runge–Kutta scheme. 相似文献
69.
Julien Ouy 《Electronic Notes in Theoretical Computer Science》2006,146(2):151
The synchronous hypothesis arose in the late Eighties as a conceptual framework for the computer-aided design of embedded systems. Along with this framework, the issue of desynchronization was simultaneously raised as the major topic of mapping the ideal communication and computation model of synchrony on realistic and distributed computer architectures.The aim of the present article is to survey the development of this topics in the particular yet promising model of one of the prominent environments that were build along these principles: Signal and its polychronous (synchronous multi-clocked) model of computation, before to give some hints and ideas about ongoing research addressing this issue. 相似文献
70.
Changes in land surface temperatures and NDVI values over Europe between 1982 and 1999 总被引:2,自引:0,他引:2
We used land surface temperature (LST) algorithms and NDVI values to estimate changes in vegetation in the European continent between 1982 and 1999 from the Pathfinder AVHRR Land (PAL) dataset. These two parameters are monitored through HANTS (Harmonic ANalysis of Time Series) software, which allows the simultaneous observation of mean value, first harmonic amplitude and phase behaviors in the same image. These results for each complete year of data show the effect of volcanic aerosols and orbital drift on PAL data. Comparison of time series of HANTS cloud-free time series with the original time series for various land cover proves that this software is useful for LST analysis, although primarily designed for NDVI applications. Comparison of yearly averages of HANTS LST over the whole Europe with air temperature confirms the validity of the results. Maps of the evolution for both parameters between periods 1982/1986 and 1995/1999 have been elaborated: NDVI data show the well confirmed trend of increase over Europe (up to 0.1 in NDVI), Southern Europe seeing a decrease in NDVI (− 0.02). LST averages stay stable or slightly decrease (up to − 1.5 K) over the whole continent, except for southern areas for which the increase is up to 2.5 K. These results evidence that arid and semi-arid areas of Southern Europe have become more arid, the rest of Europe seeing an increase in its wood land proportion, while seasonal amplitude in Northern Europe has decreased. 相似文献