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81.
82.
An efficient Cartesian cut-cell/level-set method based on a multiple grid approach to simulate turbulent turbomachinery flows is presented. The finite-volume approach in an unstructured hierarchical Cartesian setup with a sharp representation of the complex moving boundaries embedded into the computational domain, which are described by multiple level-sets, ensures a strict conservation of mass, momentum, and energy. Furthermore, an efficient kinematic motion level-set interface method for the rotation of embedded boundaries described by multiple level-set fields on a computational domain distributed over several processors is introduced. This method allows the simulation of multiple boundaries rotating relatively to each other in a fixed frame of reference. To demonstrate the efficiency of the numerical method and the quality of the computed findings the generic test problem of a rotating cylinder surrounded by a stationary hull and the flow over a ducted rotating axial fan with a stationary turbulence generating grid at the inflow are simulated. The computational results of the axial fan show a good agreement with the experimental data.  相似文献   
83.
84.
Mathematical Programming - In this paper, we present a new framework of bi-level unconstrained minimization for development of accelerated methods in Convex Programming. These methods use...  相似文献   
85.
A nonsymmetric N?×?N matrix with elements as certain simple functions of N distinct real or complex numbers r 1, r 2, …, rN is presented. The matrix is special due to its eigenvalues???the consecutive integers 0,1,2, …, N?1. Theorems are given establishing explicit expressions of the right and left eigenvectors and formulas for recursive calculation of the right eigenvectors. A special case of the matrix has appeared in sampling theory where its right eigenvectors, if properly normalized, give the inclusion probabilities of the conditional Poisson sampling design.  相似文献   
86.
87.
Previous work has shown that amylose (AM) can cross-link hydrophobically modified polymers by inclusion complexation, whereby thermoreversible cold-setting gels are formed. In this work, the competition between AM and cyclodextrin (CD) for the formation of inclusion complexes with hydrophobically modified hydroxyethyl cellulose (HMHEC) is investigated. A detailed study of viscosity, NMR self-diffusion, and chemical shifts of the two-component mixture, CD and HMHEC, was performed. The results imply that 2:1 (CD:polymer hydrophobe) complexes may be formed. The three-component mixtures, HMHEC/AM/CD, were investigated by rheology, NMR self-diffusion, and intensities of the NMR resonance peaks. The CD molecules competed efficiently with the AM molecules, as seen by a decreased storage modulus, an increased self-diffusion of AM and HMHEC, and increased NMR intensities of the HMHEC hydrophobes, as the concentration of CD increased in the solution. A high concentration of CD is needed in the mixtures to inhibit all interactions between HMHEC and AM, and it was shown that there still is an effect of AM at excess CD concentration in the mixtures.  相似文献   
88.
The problem of approximating a matrix by another matrix of lower rank, when a modest portion of its elements are missing, is considered. The solution is obtained using Newton’s algorithm to find a zero of a vector field on a product manifold. As a preliminary the algorithm is formulated for the well-known case with no missing elements where also a rederivation of the correction equation in a block Jacobi-Davidson method is included. Numerical examples show that the Newton algorithm grows more efficient than an alternating least squares procedure as the amount of missing values increases.  相似文献   
89.
90.
In this study, a method was developed for determining the concentration of the pharmaceutical fluoxetine and its metabolite, norfluoxetine, in sewage water samples. Sample preparation was performed by hollow-fibre supported liquid membrane (HF-SLM) extraction with final analysis using liquid chromatography with UV detection. Several parameters were studied including type of organic solvent, sample and acceptor pH, and salt and humic acid content. The optimised method allowed determination of the analyte at the ng/L level in sewage water. A linear plot gave a correlation coefficient better than 0.991 for both analytes and resulted in limits of detection in sewage water of 11 and 12 ng/L, for fluoxetine and norfluoxetine, respectively. The enrichment factor was over 1700 for both analytes in sewage water. The repeatability and reproducibility were better than 8% and 17%, respectively. The developed methodology was used to study daily variations of fluoxetine and norfluoxetine in municipal sewage streams. Norfluoxetine has been detected for the first time in sewage water and a preliminary analysis gave average concentrations of 150 and 225 ng/L for norfluoxetine and fluoxetine, respectively.  相似文献   
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