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  • 1
    Electronic Resource
    Electronic Resource
    Scattering of 56-Mc./s. Radio Waves from the Lower Ionosphere (1953)
    [s.l.] : Nature Publishing Group
    Nature 171 (1953), S. 352-353 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] For the 56-Mc./s. equipment, the aerial array-gain relative to a Hertzian dipole is about 16 ; the direction of maximum radiation is 6 above the horizontal ; the peak power of the transmitter pulse, 50 kW. ; the duration of the pulse, 16 pisec. ; and the receiver sensitivity, 5 X 10~13 W. The ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/171352a0
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  • 2
    Electronic Resource
    Electronic Resource
    Radar Reflexions from Auroras (1950)
    [s.l.] : Nature Publishing Group
    Nature 165 (1950), S. 561-562 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] The 3,000-Mc./s. unit is equipped with an aerial system consisting of two paraboloids with apertures of 150 cm. and giving an approximate beam-width of 3-5°. Orientation of the aerial system about horizontal and vertical axes is under the control of the radar operator. The peak transmitter ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/165561b0
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  • 3
    Electronic Resource
    Electronic Resource
    Auroral Displays at Saskatoon (1949)
    [s.l.] : Nature Publishing Group
    Nature 163 (1949), S. 774-774 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] A VERY intense auroral display was observed at Saskatoon during the night of January 24–25. The display began as a red aurora at 6.15 and the red colour persisted until 7.45; all times mentioned are Mountain Standard Time (seven hours behind G.M.T.). Some red was present at all times up to ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/163774b0
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  • 4
    Electronic Resource
    Electronic Resource
    Auroral Radiation in the 3,000-Megacycle Region (1949)
    [s.l.] : Nature Publishing Group
    Nature 164 (1949), S. 453-453 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] DURING the auroral display of January 24, short pulses of radiation were observed on the indicator of a radar set operating at a frequency of 3,000 megacycles. Since these pulses were observed even when the radar transmitter was off, it seemed probable that they were associated with the auroral ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/164453a0
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  • 5
    Electronic Resource
    Electronic Resource
    Towards a cost-effective ILU preconditioner with high level fill (1992)
    Springer
    BIT 32 (1992), S. 442-463 
    Details
    ISSN: 1572-9125
    Keywords: 65F10 ; 76S05 ; Minimum discarded fill (MDF) ; thresholdMDF ; minimum updating matrix ; matrix ordering ; preconditioned conjugate gradient
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics
    Notes: Abstract There has been increased interest in the effect of the ordering of the unknowns on Preconditioned Conjugate Gradient (PCG) methods. A recently proposed Minimum Discarded Fill (MDF) ordering technique is effective in finding goodILU(l) preconditioners, especially for problems arising from unstructured finite element grids. This algorithm can identify anisotropy in complicated physical structures and orders the unknowns in an appropriate direction. TheMDF technique may be viewed as an analogue of the minimum deficiency algorithm in sparse matrix technology, and hence is expensive to compute for high levelILU(l) preconditioners. In this work, several less expensive variants of theMDF technique are explored to produce cost-effectiveILU preconditioners. The ThresholdMDF ordering combinesMDF ideas with drop tolerance techniques to identify the sparsity pattern in theILU preconditioners. The Minimum Update Matrix (MUM) ordering technique is a simplification of theMDF ordering and is an analogue of the minimum degree algorithm. TheMUM ordering method is especially effective for large matrices arising from Navier-Stokes problems.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02074880
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  • 6
    Electronic Resource
    Electronic Resource
    Is primary CNS lymphoma really becoming more common? A population-based study of incidence, clinicopathological features and outcomes in Alberta from 1975 to 1996 (1999)
    Springer
    Annals of oncology 10 (1999), S. 65-70 
    Details
    ISSN: 1569-8041
    Keywords: brain tumors ; epidemiology ; incidence ; primary central nervous system lymphoma
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Background: The incidence of primary CNS lymphoma (PCNSL) is believed to be increasing in immunocompetent patients but this may not be universally true. The objective of this study was to determine in a population if the incidence of PCNSL is increasing, if the histologic subtypes are changing, and to describe the clinicopathologic and outcome characteristics of PCNSL. Patients and methods: We identified all Alberta residents with a histologic diagnosis of PCNSL from 1 January 1975 to 31 December 1996 using the Alberta Cancer Registry. Annual age- standardized incidence rates (ASIR), clinicopathologic and outcome characteristics were determined. Results: There were 50 immunocompetent PCNSL patients; the median age was 64 and 30 were male. Their median survival was 10.15 months. Histology was available for review in 37 (74%) patients: 19 (51%) were diffuse large cell, 16 (43%) were immunoblastic and 2 (5%) were unclassifiable malignant lymphomas. The ASIR ranged from 0.178–1.631/106 and no change in ASIR was found (test for trend, P = 0.26) for gender or age. The ASIR of malignant gliomas did not change either but increased for all other non-Hodgkin's lymphoma (94.95–138.76106; test for trend, P = 0.0001) The number of brain biopsies increased from 1979–1985 (test for trend, P 〈 0.0001) but remained stable from 1986–1996 (test for trend, P = 0.99). Conclusions: Unlike several other populations, PCNSL is not becoming significantly more common in Alberta. If this difference is real (i.e., not due to differences in cancer registry coding practices etc.) comparisons between Albertans and other populations in whom the incidence is rising may provide clues regarding the etiology of PCNSL.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1008308313914
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  • 7
    Electronic Resource
    Electronic Resource
    Three-dimensional modelling of steam flush for DNAPL site remediation (1994)
    Chichester : Wiley-Blackwell
    International Journal for Numerical Methods in Fluids 19 (1994), S. 1055-1081 
    Details
    ISSN: 0271-2091
    Keywords: Multiphase porous media flow ; Primary variable selection ; Horizontal wells ; 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: Numerical simulation of steam flush for clean-up of non-aqueous phase liquid (NAPL) contaminated groundwater sites involves solution of the multiphase, multicomponent subsurface flow equations. This paper describes techniques for discretizing problems with horizontal wells in a three-dimensiontetrahedral mesh. The effectiveness of non-linear flux limiters for reducing numerical dispersion is discussed. Primary variable selection and thermodynamic state transition rules will also be compared. Some example results for several steam flush scenarios will be presented.
    Additional Material: 21 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/fld.1650191202
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  • 8
    Electronic Resource
    Electronic Resource
    Preconditioned conjugate gradient methods for the incompressible Navier-Stokes equations (1992)
    Chichester : Wiley-Blackwell
    International Journal for Numerical Methods in Fluids 15 (1992), S. 273-295 
    Details
    ISSN: 0271-2091
    Keywords: Navier-Stokes ; ILU(l) ; Preconditioned conjugate gradient ; 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 robust technique for solving primitive variable formulations of the incompressible Navier-Stokes equations is to use Newton iteration for the fully implicit non-linear equations. A direct sparse matrix method can be used to solve the Jacobian but is costly for large problems; an alternative is to use an iterative matrix method. This paper investigates effective ways of using a conjugate-gradient-type method with an incomplete LU factorization preconditioner for two-dimensional incompressible viscous flow problems. Special attention is paid to the ordering of unknowns, with emphasis on a minimum updating matrix (MUM) ordering. Numerical results are given for several test problems.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/fld.1650150303
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  • 9
    Electronic Resource
    Electronic Resource
    A two-phase, two-component model for natural convection in a porous medium (1991)
    Chichester : Wiley-Blackwell
    International Journal for Numerical Methods in Fluids 12 (1991), S. 655-682 
    Details
    ISSN: 0271-2091
    Keywords: Two-phase ; Porous medium ; Convection ; Heat pipe ; 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 numerical study of natural convection in a two-phase, two-component flow in a porous medium heated from below is presented. Interphase mass and energy transfer, latent heat and bouyancy effects are major physical features. This study extends earlier studies of natural convection based on single-phase, saturated porous medium models. The appearance of two-phase heat pipe zones in the flow has a marked effect on the fluid and heat flows as well as on the performance of the numerical methods. The numerical techniques for handling phase change, Jacobian construction and time step selection are discussed.
    Additional Material: 17 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/fld.1650120705
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  • 10
    Electronic Resource
    Electronic Resource
    A control volume finite element method for three-dimensional NAPL groundwater contamination (1991)
    Chichester : Wiley-Blackwell
    International Journal for Numerical Methods in Fluids 13 (1991), S. 955-970 
    Details
    ISSN: 0271-2091
    Keywords: Three-dimensional tetrahedral ; NAPL contamination ; 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 three-dimensional control volume finite element method is developed for NAPL groundwater contamination problems. Tetrahedral elements are formed by decomposing deformed blocks. The decomposition is carried out in such a way as to minimize the size of the negative transmissibilities. Negative transmissibilities produce non-physical discrete fluid flow paths and can cause oscillatory behaviour in the Newton iteration. Example results are presented for a three-dimensional NAPL contamination scenario using typical geophysical data.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/fld.1650130803
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