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101.
Sans résumé 相似文献
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Elena Gómez Noelia Calvar Eugénia A. Macedo Ángeles Domínguez 《The Journal of chemical thermodynamics》2012,45(1):9-15
In this paper, physical properties of a high purity sample of the ionic liquid 1-propyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide, [PMim][NTf2], and its binary mixtures with methanol, ethanol, 1-propanol, and 2-propanol were measured at atmospheric pressure. The temperature dependence of density, refractive index and speed of sound (293.15 to 343.15) K and dynamic viscosity (298.15 to 343.15) K were studied at atmospheric pressure by conventional techniques for the pure ionic liquid. For its mixtures with alcohols, density, speed of sound, and refractive index were measured at T = 298.15 K over the whole composition range. The thermal expansion coefficient of the [PMim][NTf2] was calculated from the experimental results using an empirical equation, and values of the excess molar volume, excess refractive index, and excess molar isentropic compressibility for the binary systems at the above mentioned temperature, were calculated and fitted to the Redlich–Kister equation. The heat capacity of the pure ionic liquid at T = 298.15 K was determined using DSC. 相似文献
108.
Eugénie Hunsicker Hengguang Li Victor Nistor Ville Uski 《Numerical Methods for Partial Differential Equations》2014,30(4):1130-1151
In this article, we consider the problem of optimal approximation of eigenfunctions of Schrödinger operators with isolated inverse square potentials and of solutions to equations involving such operators. It is known in this situation that the finite element method performs poorly with standard meshes. We construct an alternative class of graded meshes, and prove and numerically test optimal approximation results for the finite element method using these meshes. Our numerical tests are in good agreement with our theoretical results.Copyright © 2014 Wiley Periodicals, Inc. Numer Methods Partial Differential Eq 30: 1130–1151, 2014 相似文献
109.
Quantitative monitoring of an activated sludge reactor using on-line UV-visible and near-infrared spectroscopy 总被引:1,自引:0,他引:1
Mafalda C. Sarragu?a Ana Paulo Madalena M. Alves Ana M. A. Dias Jo?o A. Lopes Eugénio C. Ferreira 《Analytical and bioanalytical chemistry》2009,395(4):1159-1166
The performance of an activated sludge reactor can be significantly enhanced through use of continuous and real-time process-state
monitoring, which avoids the need to sample for off-line analysis and to use chemicals. Despite the complexity associated
with wastewater treatment systems, spectroscopic methods coupled with chemometric tools have been shown to be powerful tools
for bioprocess monitoring and control. Once implemented and optimized, these methods are fast, nondestructive, user friendly,
and most importantly, they can be implemented in situ, permitting rapid inference of the process state at any moment. In this
work, UV-visible and NIR spectroscopy were used to monitor an activated sludge reactor using in situ immersion probes connected
to the respective analyzers by optical fibers. During the monitoring period, disturbances to the biological system were induced
to test the ability of each spectroscopic method to detect the changes in the system. Calibration models based on partial
least squares (PLS) regression were developed for three key process parameters, namely chemical oxygen demand (COD), nitrate
concentration (N-NO3−), and total suspended solids (TSS). For NIR, the best results were achieved for TSS, with a relative error of 14.1% and a
correlation coefficient of 0.91. The UV-visible technique gave similar results for the three parameters: an error of ~25%
and correlation coefficients of ~0.82 for COD and TSS and 0.87 for N-NO3−. The results obtained demonstrate that both techniques are suitable for consideration as alternative methods for monitoring
and controlling wastewater treatment processes, presenting clear advantages when compared with the reference methods for wastewater
treatment process qualification. 相似文献
110.
Noelia Calvar Begoña González Ángeles Domínguez Eugénia A. Macedo 《The Journal of chemical thermodynamics》2009,41(1):11-16
Measurements of osmotic coefficients of BmimCl (1-butyl-3-methylimidazolium chloride) and HmimCl (1-hexyl-3-methylimidazolium chloride) with ethanol and EmimEtSO4 (1-ethyl-3-methylimidazolium ethylsulfate) and EmpyEtSO4 (1-ethyl-3-methylpyridinium ethylsulfate) with water at T = (313.15 and 333.15) K are reported in this work. Vapour pressure and activity results of the studied binary systems are obtained from experimental measurements. The results for the osmotic coefficients are correlated using the extended Pitzer model modified by Archer and the modified NRTL (MNRTL) model. The standard deviations obtained with both models are also given. The parameters obtained with the extended Pitzer model of Archer are used to calculate the mean molal activity coefficients. 相似文献