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Resolution Methods (resolution + methods)
Selected AbstractsDetermination of Materials Selection Performance Indices Through the Combination of Numerical Modeling and Optimization MethodsADVANCED ENGINEERING MATERIALS, Issue 11 2009German Castillo After translation, the first stages traditionally involved in the materials selection are filtration and classification, which require formulation of criteria (constraints or objectives) deduced from information written in the set of material requirements. These criteria, which are representative of the behavior of the material and the studied structure, must be formulated analytically in order to be used during selection stage. However, for complex behavior, analytical processing of models is no longer possible and it can be replaced by a combination of numerical resolution methods and an optimization method which make it possible to obtain approximate formal expressions of the criteria. In this paper, a complete selection method is proposed. The method is applied to the constraints as well as the objectives, in order to carry out the filtration and classification stages at the same time. The study of the thermomechanical behavior of a machine tool frame has been used to demonstrate the validity of the proposed method. [source] Numerical analysis of a 3D hydrodynamic contactINTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN FLUIDS, Issue 12 2006Costin Alin Caciu Abstract We study here the numerical analysis of a hydrodynamic contact in a particular configuration: the 3D incompressible viscous flow of a fluid dragged by a smooth plate over a rough surface. The mathematical model takes into account and discretizes the local topography of the rough profile. The simulation outcome will be the 3D velocity and pressure fields of the fluid film within the contact borders. This work is limited to the study of numerical resolution methods working solely in finite differences. The algorithms will be tested by analysing and comparing their results with analytically known flows. Copyright © 2006 John Wiley & Sons, Ltd. [source] Noise propagation and error estimations in multivariate curve resolution alternating least squares using resampling methodsJOURNAL OF CHEMOMETRICS, Issue 7-8 2004Joaquim Jaumot Abstract Different approaches for the calculation of prediction intervals of estimations obtained in multivariate curve resolution using alternating least squares optimization methods are explored and compared. These methods include Monte Carlo simulations, noise addition and jackknife resampling. Obtained results allow a preliminary investigation of noise effects and error propagation on resolved profiles and on parameters estimated from them. The effect of noise on rotational ambiguities frequently found in curve resolution methods is discussed. This preliminary study is shown for the resolution of a three-component equilibrium system with overlapping concentration and spectral profiles. Copyright © 2004 John Wiley & Sons, Ltd. [source] Combination of GC-MS with local resolution for determining volatile components in si-wu decoctionJOURNAL OF SEPARATION SCIENCE, JSS, Issue 1-2 2003Fan Gong Abstract In this paper, the combination of gas chromatography-mass spectrometry with chemometric local resolution techniques such as subwindow factor analysis (SFA) and orthogonal projection resolution (OPR) is investigated as a method of determining volatile components present in a traditional Chinese medicinal formulation known as si-wu decoction and its two individual herbs Rhizoma chuanxiong and Radix angelicae sinensis. In order to validate the reliability of the results obtained, the volatile components of interest were further separated on open glass columns and then analyzed in the same way as above. With the help of SFA and OPR approaches, the purity of chromatographic peaks can first be identified. Then, the pure chromatogram and mass spectrum of each component involved in a target peak cluster can be easily resolved and subsequently subjected to similarity searches in the NIST MS database to qualitatively and quantitatively determine the volatile components. Our results showed that about 127, 80, and 97 chemical components could be separated and 81, 49, and 55 of them identified, representing 83.95%, 91.86%, and 85.11% of the total relative content of volatile components from Rhizoma chuanxiong, Radix angelicae sinensis, and si-wu decoction, respectively. The results obtained in this work strongly indicate that the combination of GC-MS with chemometric local resolution methods could greatly improve the chromatographic separation ability by means of mathematical approaches. Moreover, they indicated the reliability and practicability of this combined technique. [source] Analysis of volatile fractions of Schisandra chinensis (Turcz.) Baill. using GC-MS and chemometric resolutionPHYTOCHEMICAL ANALYSIS, Issue 1 2003Xiao-Ning Li Abstract The two-dimensional data obtained from GC-MS has been used qualitatively and quantitatively to determine the components of the volatile fractions of Schisandra chinensis obtained by six different extraction methods. Sub-window factor analysis (SFA) was employed to confirm the identities of components determined in different samples. With the help of SFA, and other chemometric techniques, peak purity in the chromatograms was determined, and overlapping peaks were resolved to yield a pure chromatographic profile and mass spectrum for each component. It is demonstrated that the accuracy of qualitative and quantitative analysis may be greatly enhanced using chemometric resolution methods, such methods being particularly valuable with respect to the analysis of complex samples such as traditional Chinese medicines. It is further demonstrated that different extraction methods give rise to volatile fractions of S. chinensis which differ qualitatively and quantitatively in their composition. Copyright © 2003 John Wiley & Sons, Ltd. [source] | ||||||||||