We introduce a unified sensitivity concept for shape and topological perturbations and perform the sensitivity analysis for a discretized PDE-constrained design optimization problem in two space dimensions. We assume that the design is represented by a piecewise linear and globally continuous level set function on a fixed finite element mesh and relate perturbations of the level set function to perturbations of the shape or topology of the corresponding design. We illustrate the sensitivity analysis for a problem that is constrained by a reaction-diffusion equation and draw connections between our discrete sensitivities and the well-established continuous concepts of shape and topological derivatives.
View Article and Find Full Text PDFAccording to most experts, integrated and sustainable solid waste management should not only be given top priority, but must go beyond technical aspects to include various key elements of sustainability to ensure success of any solid waste project. Aside from project sustainable impacts, the overall enabling environment is the key feature determining performance and success of an integrated and affordable solid waste system. This paper describes a project-specific approach to assess typical success or failure factors.
View Article and Find Full Text PDFJ Chromatogr A
April 2005
Analysis of p,p'-DDT in solid environmental samples, like soil or sediment, requires monitoring the breakdown of this insecticide during sample preparation and measurement, which produces mainly p,p'-DDD and p,p'-DDE. The occurrence of matrix-enhanced p,p'-DDT degradation during GC injection is a well-known phenomenon; careful cleaning and pre-treatment of the GC injection port enables for an overcoming of this problem. Modern solid-liquid extraction methods apply high temperatures and/or pressures to enhance the extraction kinetics and diffusion rates of the target compounds from the solid matrix.
View Article and Find Full Text PDFJ Biochem Biophys Methods
October 2004
The aim of any extraction method in analytical chemistry is to effectively separate the analytes from the matrix with minimal solvent and time required. In this study, a comparison of the classical Soxhlet extraction and some new turbulent solid-liquid extraction techniques, such as fluidized-bed extraction (FBE), modified dive-in fluidized-bed extraction (dive-in FBE), modified dive-in Soxhlet extraction (dive-in SE) and dive-in thimble extraction (dive-in TE) for the determination of organochlorine pesticides (OCPs) was carried out. The turbulent extraction methods were performed by using the fexIKA vario control series extractor and by modification of the extraction system to dive-in technique, respectively.
View Article and Find Full Text PDFJ Biochem Biophys Methods
October 2004
The main outcome of this work is elaboration of classification models for edible oil samples representing the most widespread brands of Austrian pumpkin seed oil. A complete spectral characterisation of the pumpkin seed oil samples by UV-Vis, NIR and FTIR spectra was obtained together with their basic sensorial classification. Chemometrical processing of the measured data enabled the detection of the most important spectral features, which are crucial for categorising the oils into two or three classes according to their sensory quality evaluated by a panel of experts.
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