A qualocation method for Burgers’ equation

In this paper, a qualocation method for the one-dimensional Burgers’ equation is proposed. A semidiscrete scheme along with optimal error estimates is discussed. Results of a numerical experiment performed support the theoretical results.     

Finite element approximation to global stabilization of the Burgers’ equation by Neumann boundary feedback control law

In this article, we discuss global stabilization results for the Burgers’ equation using nonlinear Neumann boundary feedback control law. As a result of the nonlinear feedback control, a typical nonlinear problem is derived. Then, based on C ⁰-conforming finite element method, global stabilization results for the semidiscrete solution are analyzed. Further, introducing an auxiliary projection, optimal error estimates in \(L^{\infty }(L^{2})\), \(L^{\infty }(H^{1})\) and \(L^{\infty }(L^{\infty })\)-norms for the state variable are obtained. Moreover, superconvergence results are established for the first time for the feedback control laws, which preserve exponential stabilization property. Finally, some numerical experiments are conducted to confirm our theoretical findings.     

Discontinuous Galerkin finite volume element methods for second‐order linear elliptic problems

In this article, a one parameter family of discontinuous Galerkin finite volume element methods for approximating the solution of a class of second‐order linear elliptic problems is discussed. Optimal error estimates in L² and broken H¹‐ norms are derived. Numerical results confirm the theoretical order of convergences. © 2009 Wiley Periodicals, Inc. Numer Methods Partial Differential Eq, 2009     

Finite volume element method for the incompressible miscible displacement problems in porous media

We present the finite volume element method (FVEM) for incompressible miscible displacement problems in porous media. Optimal error estimates in L^∞(L²) are derived for velocity and concentration. Numerical experiments are also presented. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)     

Erratum to: Osmo-dehydration of apple pulp studied by means of classical and Knudsen Thermogravimetric approach

Classical thermogravimetry and its modification with Knudsen cells were employed to quantitatively investigate the osmo-dehydration of apple pulp samples. The data allowed realization of the complex mechanism of the process, which is not a mere solvent depletion, since it also implies sugar exchanges between the apple tissue and the hypertonic syrup used to dehydrate the fruit. The comparison between different hypertonic syrups, all at the same water activity, showed that maltose is more effective than either sucrose or a mixture of sugars that mimics the saccharide content of the apple. The conclusions are supported by a thermodynamic analysis of the aqueous solutions of these sugars at a concentration level as large as that of the hypertonic syrups used for the osmo-dehydration process.     

Einige Besonderheiten der Micellenbildung oxy?thylierter aliphatischer Alkohole

Ohne Zusammenfassung     

Investigation of the completeness of digestion procedures prior to voltammetric trace metal analysis of olive leaves

Summary Wet decomposition of olive leaves in open and closed systems, low temperature ashing, UV-irradiation and combinations of these methods have been tested for their application in the determination of heavy metals by anodic stripping voltammetry. Completeness of the decompositon and interferences in the electrochemical determination have been evaluated. Wet decomposition with perchloric acid, low temperature ashing and a combination of pressurized digestion and UV-irradiation were found to be suitable for application in electrochemical measurements. The most serious interferences were observed with well but not fully decomposed samples, such as those obtained by wet decomposition with nitric acid in an open system.

---

Untersuchung der Vollständigkeit von Aufschlußverfahren für die voltammetrische Spurenmetall-Analyse von Oliven-Blättern

     

Thermal desorption comprehensive two-dimensional gas chromatography for in-situ measurements of organic aerosols

The complexity of organic composition and temporal variability of atmospheric aerosols presents an extreme analytical challenge. Comprehensive two-dimensional gas chromatography (GC x GC) has been used on time integrated filter samples to reveal the presence of thousands of individual organic compounds in aerosols, but without defining the temporal variability in composition ideal for providing information on source resolution and human exposure to specific pollutants. We hereby introduce a new instrument, 2D-TAG, which combines our in-situ thermal desorption aerosol GC (TAG) instrument with GC x GC allowing for dramatically improved separation of organics with automated measurements at hourly timescales.     

Development of a new consumable-free thermal modulator for comprehensive two-dimensional gas chromatography

A simple and cost-effective GC × GC modulator requiring no moving parts or consumables, hence suitable for field analysis and monitoring, was developed. The modulator was constructed from a specially designed Silcosteel^® trapping capillary, installed outside the GC oven, and coated inside with polydimethylsiloxane (PDMS) stationary phase. Dual-stage modulation was accomplished by resistively heating alternate segments of the trap with a custom-designed capacitive discharge power supply. The performance of the proposed modulator was comparable to many GC × GC systems currently in use, with the injection band widths as low as 60 ms at half height. With proper selection of the stationary phase in the trap, the modulator can be used for the analysis of complex mixtures with volatility range spanning from n-C5 to n-C40.