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排序方式: 共有119条查询结果,搜索用时 15 毫秒
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A PDE based and interpolation-free framework for modeling the sifting process in a continuous domain
El Hadji S. Diop Radjesvarane Alexandre Valérie Perrier 《Advances in Computational Mathematics》2013,38(4):801-835
The empirical mode decomposition (EMD) is a powerful tool in signal processing. Despite its algorithmic origin making its theoretical analysis and formulation very difficult, a few recent works has contributed to its theoretical framework. Herein, the former local mean is formulated in a more convenient way by introducing operators to calculate local upper and lower envelopes. This enables the use of differential calculus and other classical calculations on the new local mean. Based on its more accurate formulation, a partial differential equation (PDE) consistency result is provided to approximate the sifting process iterations, without any envelope interpolation. In addition, a new stopping criterion based on the introduced local mean is proposed. This new criterion is a local measure and resolves the null integral conservative property of the previous derived PDE, which made any signal having a null integral be a PDE-based mode. Moreover, the δ inner model parameter is now linked to the signal intrinsic properties, providing to the latter a physical meaning and making the proposed model keep the auto-adaptive property of the EMD. New decomposition modes are now analytically and fully characterized, and also interpolation free. Finally, properties of the interpolation free PDE model are presented. Results obtained with our proposed approach by explicit computations thanks to the eigendecomposition of the Laplacian operator, and also by numerical resolution of the derived PDE, show noticeable improvements for both stationary and non stationary signals, in comparison to the former EMD algorithm. 相似文献
4.
Relative molar responses (RMRs) of some straight-chain aliphatic alkanes, ketones, aldehydes, alcohols, carboxylic acids, primary amines, aniline, and nitrobenzene derivatives were investigated related to naphthalene. Most of the respective compounds have not been investigated yet due to their high polarity or high boiling point. The earlier cross section data for oxygenated compounds were changed to RMRs which are more utilizable from an analytical aspect. A linear correlation was found between the RMRs and the carbon atom numbers in primary amines. In the cases of aniline and nitrobenzene derivatives the RMRs were also determined; however, no functional relationship was found. The measurement conditions, i.e., the type of column affect the apparent RMRs of aliphatic primary amines. A midpolar column having a higher maximum operating temperature provides a more sensitive apparent RMR (Rtx-1701) than the basic polar column having a lower maximum temperature (Stabilwax-DB), because a high temperature allows setting a higher injector temperature and a higher amount of compound can reach the ion source. Knowing correlations the quantitative analysis passes into easier and fewer reference materials are needed to investigate a sample having many components, because the sensitivities can be determined from the correlations studied in this paper. This is also valid for aromatic compounds, even though no functional relationship exists. 相似文献
5.
A carbon paste electrode (graphite, ion-exchange polymer, transition cations, buffer electrolyte) was achieved and the properties of the compounds were studied. The range of pH over which the metallic cation is most fixed on the polymer was determined. Electronic conductivity measurements of the samples show that their resistance increases greatly when the ratio of polymerised active material exceeds 50%. 相似文献
6.
I. Diop N. David J.M. Fiorani R. Podor M. Vilasi 《The Journal of chemical thermodynamics》2009,41(3):420-432
In the present work, the experimental characterization of the pseudo-binary PbO–Bi2O3 cut has been performed by differential thermal analysis (DTA), isothermal annealing, powder X-ray diffraction analysis (XRD), scanning electron microscopy (SEM), and electron probe microanalysis (EPMA). A thermodynamic assessment according to the Calphad method was also performed based on the present results as well as previous experimental data using the ThermoCalc software. 相似文献
7.
Delahaye É Eyele-Mezui S Diop M Leuvrey C Rabu P Rogez G 《Dalton transactions (Cambridge, England : 2003)》2010,39(44):10577-10580
Synthesis of new heterometallic layered magnets with controlled chirality have been achieved by insertion of chiral and non-chiral salen-type Ni(II) complexes into copper and cobalt layered simple hydroxides. 相似文献
8.
Viera Mrázová Ján Mocák Adriána Bednárová Ján Balla 《Central European Journal of Chemistry》2010,8(6):1216-1222
The objective of this work was a correct statistical comparison of two assay methods for determination of glycated haemoglobin
HbA1c. The immunoturbidimetric determination of HbA1c was performed in two ways: using an automatic analyser Hitachi 912,
calibrated according to the IFCC reference system (International Federation of Clinical Chemistry and Laboratory Medicine)
and using an analyser Advia 1200 and the NGSP reference system (National Glycohaemoglobin Standardization Program). For statistical
comparison of these two analytical methods several advanced regression methods were used, which respect random errors of both
compared methods. Specifically, Deming regression with and without weights, orthogonal regression, and Passing-Bablok regression
were employed. The results demonstrate that the investigated analytical assay methods do not correspond to each other. The
summarized results indicate usefulness of better harmonisation of two existing reference systems. 相似文献
9.
Summary The effect of adding an electrolyte and increasing the temperature on the preconcentration of volatile compounds in headspace
analysis has been investigated. Quantification of the interactive effects of temperature and addition of salt on the vapor
concentration is of interest for the determination of trace organic impurities in pharmaceutical base materials. This study
was undertaken to investigate the quantitative effects of the addition of salts alcohols, and acetone, and of increasing the
temperature on the vapor concentrations and distribution coefficients of volatile aromatic compounds (benzene, toluene, ando-xylene). It was found that the concentration of aromatic compound residues in the headspace could be increased by adding
an inert salt to the water, but this effect was not very significant because of the low orginal solubility of the aromatic
compounds in water. The reverse effect can be achieved by use of polar organic additives; this can be explained by the high
polarizability of aromatic compounds and their greater solubility in the presence of these solvents.
Presented at Balaton Symposium on High-Performance Separation Methods, Siófok, Hungary, September 1–3, 1999. 相似文献
10.
Hyder H. Balla Shahrir Abdullah Wan Mohd Faizal WanMahmood M. Abdul Razzaq Rozli Zulkifli Kamaruzaman Sopian 《Research on Chemical Intermediates》2013,39(6):2801-2815
A metallic nanofluid is a suspension of metallic nanoparticles in a base fluid. Multi-metallic nanoparticles are a combination of two or more types of metallic particles. Such multi-metallic nanoparticles were suspended in water using an ultrasonic vibrator for different total volume fractions and different ratios of metallic/metallic nanoparticles. A transient hot wire setup was built to measure the thermal conductivity of the nanofluid at different temperatures. The experimental results were in good agreement with the results in the literature. Then, the experimental results were used as input data for an adaptive neural fuzzy inference system (ANFIS) to predict the thermal conductivity of the multi-metallic nanofluid. The maximum deviation between the ANFIS results and experimental measurements was 1 %. The predicted results and the experimental data were compared with other models. The ANFIS model was found to have good ability to predict the thermal conductivity of the multi-metallic nanofluid over the range of the experimental results. 相似文献