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  • 1
    Electronic Resource
    Electronic Resource
    Convergence acceleration of iterative solutions of Euler equations for transonic flow computations (1986)
    Springer
    Computational mechanics 1 (1986), S. 165-176 
    Details
    ISSN: 1432-0924
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract In this paper, two acceleration techniques for Euler calculations are investigated. The first technique is an extrapolation procedure based on the Power Method; it is applicable when the iterative matrix has dominant eigenvalues. Both real and complex conjugate roots are allowed. The second technique is a generalization of the Minimal Residual Method, where the extrapolation step consists of a weighted combination of the corrections at different iteration levels and the weights are chosen to minimize the L 2-norm of the residual. Numerical results, using Jameson's Runge-Kutta Multigrid Code, are presented. The extra computational work to apply either technique is negligible and the extra storage is not a problem on current supercomputers.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00272622
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  • 2
    Electronic Resource
    Electronic Resource
    Spinal dysraphism: experience with 250 cases operated upon (1989)
    Springer
    Child's nervous system 5 (1989), S. 324-329 
    Details
    ISSN: 1433-0350
    Keywords: Spinal dysraphism ; Spina bifida aperta ; Spina bifida occulta ; Assessment ; Multidisciplinary approach
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract During a period of 4 years (December 1983—December 1987) 250 children were operated upon by the authors. At the outpatient clinic of the New Children's Hospital 313 infants and children suffering a myelodysraphic lesion were seen, 63 of whom were not treated surgically owing to the presence of severe hydrocephalus in 16 cases and complete flaccid paraplegia with marked sphincteric disturbances in 47. All of the patients came from poor families. Malnutrition, many siblings per family, poor maternal care, and repeated pregnancies and abortions have added to the large incidence of such a handicap in Egypt. The clinical features, diagnosis, and management of 200 cases of spina bifida aperta (SBA) and 50 of spina bifida occulta (SBO) are summarized. SBA cases were operated upon as soon as possible from the time of their presentation; their preliminary assessment included an exhaustive general, neurological, urological, and orthopedic examination; and investigations such as plain X-rays to the back and skull, CT scanning of the cranium, spinal myelogram, and metrizamide CT scanning to the back were performed. The surgical outcome is far from being satisfactory in the sense of producing an ambulatory, intelligent, healthy individual, especially in a meningomyelocele patient having a high-level lesion. The authors believe that there is still much to be done for these children marked by fate, and the neurosurgeon should be one among several other physicians devoted to the amelioration or at least the prevention of worsening, if possible, of the condition in such unfortunate and handicapped children.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00274523
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  • 3
    Electronic Resource
    Electronic Resource
    Population fluctuations on parasites ofLepidosaphes beckii Newm. andCeroplastes floridensis Comst. (1987)
    Springer
    Journal of pest science 60 (1987), S. 6-9 
    Details
    ISSN: 1612-4766
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Description / Table of Contents: Zusammenfassung Lepidosaphes beckii Newm. (Hom., Diaspididae) undCeroplastes floridensis Comst. (Hom., Coccidae) sind im Raum Alexandria, Ägypten, dominante Schädlinge anCitrus-Bäumen (Citrus sinensis). Bei einer einjährigen Untersuchung ihrer Parasiten wurden 6 Hymenopteren-Arten als Primärparasiten vonL. beckii gefunden:Aphytis lepidosaphes Comp.,A. bispanicus Comp.,Encarsia (Prospaltella) spp.,Aspidiotiphagus citrinus Craw,Aphytis lingnanensis Comp. sowie der SekundärparasitMarietta javensis Howard. Unter ihnen warA. lepidosaphes der Hauptparasit. BeiC. floridensis wurden 4 Hymenopteren-Arten als Parasiten festgestellt:Tetrastichus ceroplastae (Gir.),Aspidiotiphagus citrinus Craw,Metaphycus flavus (Howard) undMicroterys flavus (Howard). Die genannten Parasitenarten werden näher betrachtet.
    Notes: Abstract Lepidosaphes beckii Newm. (Hom., Diaspididae) andCeroplastes floridensis Comst. (Hom., Coccidae), are dominant pests on citrus trees (Citrus sinensis), in Alexandria district. The population fluctuations of the parasites of both insects were studied during a whole year. Six species of hymenopterous primary parasites together with one secondary parasite were found onL. beckii. These species wereAphytis lepidosaphes Compere,A. bispanicus Compere,Encarsia (Prospaltella) spp.,Aspidiotiphagus citrinus Craw,Aphytis lingnanensis Compere, and the secondary parasiteMarietta javensis Howard.A. lepidosaphes was the most common parasite onL. beckii. ConcerningC. floridensis, four species of hymenopterous parasites were found, namelyTetrastichus ceroplastae (Girault),Aspidiotiphagus citrinus Craw,Metophycus flavus (Howard), andMicroterys flavus (Howard).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01903930
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  • 4
    Electronic Resource
    Electronic Resource
    Thermal studies on anisaldehyde carbohydrazone methyl trimethylammonium chloride complexes of zinc, cadmium and mercury (1987)
    Springer
    Journal of thermal analysis and calorimetry 32 (1987), S. 945-948 
    Details
    ISSN: 1572-8943
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The kinetic parameters of the thermal decomposition of Zn, Cd and Hg(II) hydrazone complexes of the general formula [MCl2(AGT)2]Cl2, where AGT=anisaldehyde carbohydrazone methyl trimethylammonium cation, $$CH_3 O - C_6 H_4 - CH = N - NH - CO - CH_2 - \mathop N\limits^ + (CH_3 )_3 ,$$ and M=Zn, Cd and Hg(II), have been determined from the corresponding thermal curves. The order of the reaction (n) and the activation energy (E a) have been derived. The kinetic data are discussed in terms of the effect of the metal ion on the activation energy. A thermal decomposition mechanism is suggested.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01913781
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  • 5
    Electronic Resource
    Electronic Resource
    Radiolysis of NTA complexes with U(VI), Fe(III) and Ni(II) (1987)
    Springer
    Journal of radioanalytical and nuclear chemistry 111 (1987), S. 17-26 
    Details
    ISSN: 1588-2780
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract The radiolysis of NTA complexes with U(VI), Fe(III) and Ni(II) has been studied spectrophotometrically at different pH values, at different doses of60Co gamma-radiation. The absorbed doses were measured using the Fricke dosimeter. A clear relation between the radiolytic degradation of the complexes and the ligand concentration was observed. The G values were computed and compared with that of G(OH).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02060517
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  • 6
    Electronic Resource
    Electronic Resource
    Effect of gamma radiation on di- and trivalent cobalt nitrilotriacetates (1989)
    Springer
    Journal of radioanalytical and nuclear chemistry 131 (1989), S. 391-398 
    Details
    ISSN: 1588-2780
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract Gamma irradiation of di- and trivalent cobalt nitrilotriacetic acid (NTA) chelates was performed both in the presence and absence of oxygen (air). A radiolytic mechanism is proposed where it has been shown that degradation of the cobalt chelates is due to OH radicals formed during radiolysis.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02060605
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  • 7
    Electronic Resource
    Electronic Resource
    Conservative calculations of non-isentropic transonic flows (1985)
    Chichester : Wiley-Blackwell
    International Journal for Numerical Methods in Fluids 5 (1985), S. 1047-1057 
    Details
    ISSN: 0271-2091
    Keywords: Transonic Flow ; Modified Potential ; Finite Elements ; Non-isentropic Flow ; Conservative Method ; 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: The classical potential formulation of inviscid transonic flows is modified to account for non-isentropic effects. The density is determined in terms of the speed as well as the pressure, which in turn is calculated from a second-order mixed-type equation derived via differentiating the momentum equations.The present model differs in general from the exact inviscid Euler equations since the flow is assumed irrotational. On the other hand, since the shocks are not isentropic, they are weaker and are placed further upstream compared to the classical potential solution. Furthermore, the streamline leaving the aerofoil does not necessarily bisect the trailing edge.Results for the present conservative calculations are presented for non-lifting and lifting aerofoils at subsonic and transonic speeds and compared to potential and Euler solutions.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/fld.1650051204
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  • 8
    Electronic Resource
    Electronic Resource
    Improved relaxation schemes for transonic potential calculations (1988)
    Chichester : Wiley-Blackwell
    International Journal for Numerical Methods in Fluids 8 (1988), S. 1-16 
    Details
    ISSN: 0271-2091
    Keywords: Transonic flows ; Potential equations ; Relaxation methods ; 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: A block relaxation scheme, grouped in a red-black ordering, is applied to transonic aerofoil calculations using body-fitted co-ordinates. The scheme is simple and easily vectorizable. Detailed comparisons with the approximate factorization method (AF2) are presented and it is shown that the new scheme is competitive in all cases considered. Transonic results, of engineering accuracy, on an 0-type grid of 149 × 30 points, are usually obtained within 200 iterations (≃ 40s on a Cyber 175).
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/fld.1650080102
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  • 9
    Electronic Resource
    Electronic Resource
    Computation of three-dimensional transonic flows using two stream functions (1988)
    Chichester : Wiley-Blackwell
    International Journal for Numerical Methods in Fluids 8 (1988), S. 17-29 
    Details
    ISSN: 0271-2091
    Keywords: Three-dimensional transonic flows ; Vector potential ; 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: A computational method for three-dimensional flows is presented in terms of two stream functions, which may be considered as two components of a generalized vector potential. An iterative scheme is developed such that only a sequence of two-dimensional-like problems, for each function, is solved. The convergence of the iterative scheme is studied based on von Neumann linear analysis. For transonic flow calculation, numerical methods used for potential flows are readily applied, namely artificial density and Zebra relaxation. Results of transonic flow calculations around a wing are presented.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/fld.1650080103
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  • 10
    Electronic Resource
    Electronic Resource
    Entropy and vorticity corrections for transonic flows (1988)
    Chichester : Wiley-Blackwell
    International Journal for Numerical Methods in Fluids 8 (1988), S. 31-53 
    Details
    ISSN: 0271-2091
    Keywords: Non-isentropic transonic flows ; Non-uniqueness ; Stream function solutions ; 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: Different models for inviscid transonic flows are examined. The common assumptions that the flow is isentropic and irrotational are critically evaluated. Entropy and vorticity correction procedures for potential and stream function formulations are presented, together with the details of the treatment of shocks and wakes, and drag and lift calculations. The non-uniqueness problem of the potential formulation is studied using different artificial viscosity forms. Numerical results are compared with Euler solutions.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/fld.1650080104
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