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  • Incompressible  (2)
  • AMS(MOS): 65N30  (1)
  • Clearances  (1)
  • 1
    Electronic Resource
    Electronic Resource
    A three-dimensional quadratic nonconforming element (1985)
    Springer
    Numerische Mathematik 46 (1985), S. 269-279 
    Details
    ISSN: 0945-3245
    Keywords: AMS(MOS): 65N30 ; CR: G1.8
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics
    Notes: Summary We define a second-degree nonconforming element on tetrahedra. We build a basis for the opproximation space derived from this element. We prove a discrete regularity property similar to the one that holds for the corresponding two-dimensional element.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01390424
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Serum concentrations and clearances of folic acid and pyridoxal-5′-phosphate during venovenous continuous renal replacement therapy (1999)
    Springer
    Intensive care medicine 25 (1999), S. 594-598 
    Details
    ISSN: 1432-1238
    Keywords: Key words Hemofiltration ; Hemodiafiltration ; Folic acid ; Vitamin B6 ; Clearances ; Micronutrient
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Objective: To determine to what extent hydrosoluble vitamins are removed by continuous renal replacement therapy (CRRT); to evaluate clearances, removal rates, and evolution of serum concentrations of folic acid and pyridoxal-5′-phosphate (P-5′-P), the active moiety of vitamin B6 during CRRT. Design: A prospective, non-interventional, descriptive study on vitamin losses induced by CRRT. Setting: Medical and surgical intensive care units in a tertiary university-affiliated hospital. Patients: A total of ten critically ill patients in oligoanuric acute renal failure (five treated by continuous venovenous hemofiltration and five by continuous venovenous hemodiafiltration) with a mean effluent rate of 1801 ± 468 ml/h. Nutritional support was not modified and additional vitamin supplements were not provided during study periods. Measurements and results: Concentrations of folic acid and P-5′-P were determined daily during CRRT. Samples for folic acid, P-5′-P, urea, and creatinine were taken simultaneously from the blood at the dialyzer inlet and from the effluent, at CRRT initiation, and daily thereafter over an average of 3.4 ± 1.2 days. Samples were processed by immunochemiluminescence for folic acid and by radioenzymatic assay for P-5′-P determinations with normal ranges above 6.8 nmol/l and from 11.5 to 179.3 nmol/l, respectively. Marked decreases in serum folic acid and P-5′-P concentrations were noticed over time with mean daily reductions of 12.6 and 13.7 %. Serum folic acid concentrations decreased from 42.7 to 16.0 nmol/l and serum P-5′-P decreased from 14.4 to 5.0 nmol/l in the blood coming in to the dialyzer over the study period. Clearances and removal rates were determined from the effluent side. During CRRT, mean (± SEM) folic acid and P-5′-P clearances were 20.5 ± 6.3 ml/min (n = 34) and 13.2 ± 10.6 ml/min (n = 22), whereas mean urea clearance was 27.1 ± 5.1 ml/min (n = 26). Folic acid and P-5′-P removal rates were 27.0 ± 34.2 and 3.4 ± 2.0 nmol/h, corresponding to mean daily losses of nearly 650 and 80 nmol/day respectively. Conclusion: Significant losses of folic acid and P-5′-P (and most likely of other hydrosoluble vitamins) occur during CRRT. Considering that stores of most hydrosoluble vitamins are relatively low in critically ill patients, supplementation should be provided to patients treated similarly.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s001340050908
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Experiments with several elements for viscous incompressible flows (1985)
    Chichester : Wiley-Blackwell
    International Journal for Numerical Methods in Fluids 5 (1985), S. 911-928 
    Details
    ISSN: 0271-2091
    Keywords: Incompressible ; Finite Elements ; Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: We present a numerical procedure to eliminate internal nodes from elements designed to approximate incompressible flow problems. We compare six elements in academic and industrial like flow problem and we discuss their relative qualities. A surprising conclusion is that richer elements may behave less well than simple ones if a good enforcement of incompressibility is not maintained.
    Additional Material: 15 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/fld.1650051005
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    Paper (German National Licenses)
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  • 4
    Electronic Resource
    Electronic Resource
    Some special purpose preconditioners for conjugate gradient-like methods applied to CFD (1993)
    Chichester : Wiley-Blackwell
    International Journal for Numerical Methods in Fluids 16 (1993), S. 581-596 
    Details
    ISSN: 0271-2091
    Keywords: Unsteady ; Incompressible ; Viscous ; Transonic ; Supersonic ; Euler equations ; Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Standard preconditioners such as incomplete LU decomposition perform well when used with conjugate gradient-like iterative solvers such as GMRES for the solution of elliptic problems. However, efficient computation of convection-dominated problems requires, in general, the use of preconditioners tuned to the particular class of fluid-flow problems at hand. This paper presents three such preconditioners. The first is applied to the finite element computation of inviscid (Euler equations) transonic and supersonic flows with shocks and uses incomplete LU decomposition applied to a matrix with extra artificial dissipation. The second preconditioner is applied to the finite difference computation of unsteady incompressible viscous flow; it uses incomplete LU decomposition applied to a matrix to which a pseudo-compressible term has been added. The third method and application are similar to the second, only the LU decomposition is replaced by Beam-warming approximate factorization. In all cases, the results are in very good agreement with other published results and the new algorithms are found to be competitive with others; it is anticipated that the efficiency and robustness of conjugate-gradient-like methods will render them the method of choice as the difficulty of the problems that they are applied to is increased.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/fld.1650160703
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    Paper (German National Licenses)
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