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  • 1
    Electronic Resource
    Electronic Resource
    The impact of Phytophthora disease on riparian populations of common alder (Alnus glutinosa) in southern Britain (1999)
    Oxford, UK : Blackwell Publishing Ltd
    Forest pathology 29 (1999), S. 0 
    Details
    ISSN: 1439-0329
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: In 1994 a survey was established to obtain information on Phytophthora disease of common alder (Alnus glutinosa) on the riverbanks of southern England and east Wales. Within an area of 70 000 km2 63 observation plots were set up on stretches of river over 8 m wide. Average alder densities varied widely in different parts of the survey area; from 0.7 to 22.2 trees per 100 m of river. From the density figures and data on the total length of rivers over 8 m wide within the survey area, it was estimated that there were approximately 585 000 alder trees growing on the banks of such rivers.In 1994 3.9% of the trees showed crown symptoms of Phytophthora disease, and an additional 1.2% of trees were dead, although not all of these had been killed by Phytophthora. The disease occurred widely through the survey area with an indication that the highest percentage of affected trees was to be found in the south-east of England. Subsequent surveys showed that the combined percentage of symptomatic and dead trees rose to 6.0% in 1995 and to 7.9% in 1996. In the latter year, for an alder population of 585 000 trees, this would correspond to 32 800 symptomatic and 13 500 dead trees.The percentage of trees showing symptoms was seven times as high in trees growing within 1 m of the riverbank as in trees growing between 1 and 10 m of the bank. An examination of the relationships between disease incidence and various indices of water pollution revealed a positive association with total oxidized nitrogen. These results are discussed in relation to the biology and possible origin of the disease.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1439-0329.1999.00129.x
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  • 2
    Electronic Resource
    Electronic Resource
    A multi-vortex model of leading-edge vortex flows (1983)
    Chichester : Wiley-Blackwell
    International Journal for Numerical Methods in Fluids 3 (1983), S. 543-565 
    Details
    ISSN: 0271-2091
    Keywords: Low-aspect Ratio Wings ; Leading-edge Separation ; Vortex Shedding ; 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 multi-vortex model of the vortex sheets shed from the sharp leading edges of slender wings is considered. The method, which is developed within the framework of slender-body theory, is designed to deal with those situations in which more than one centre of rotation is formed on the wing, for example on a slender wing with lengthwise camber or with a strake. Numerical results are presented, firstly for situations where comparison can be made with a vortex sheet model and secondly for cases, such as those described above, where a vortex sheet model is unable to describe the flow. Where comparison is available, agreement is good and in the cases where more than one vortex system is present interesting interactions are obtained.
    Additional Material: 16 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/fld.1650030603
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    The modelling of aerodynamic flows by solution of the euler equations on mixed polyhedral grids (1992)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 35 (1992), S. 2003-2029 
    Details
    ISSN: 0029-5981
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: In this paper, an algorithm for obtaining solutions to the compressible Euler equations on mixed polyhedral grids is described. These grids, which are, in general, composed of hexahedral, pentahedral and tetrahedral elements, are used in the modelling of aerodynamic flows over complex three-dimensional geometries. The hexahedra are grouped into regular blocks, while the other elements are part of irregular grid regions, giving rise to the term “hybrid grid approach”. The interconnection of the grid elements is defined by an efficient data structure, which supplies the required information to drive the Euler algorithm. In fact, cell-vertex and cell-centre spatial discretization variants of this algorithm are detailed, along with an explicit time-marching scheme for obtaining steady-state solutions. Results on two geometrically simple configurations provide an evaluation of these solution techniques, whilst the focus on a third, complex configuration, demonstrates the potential of the method in addressing the flow over general aircraft geometries.
    Additional Material: 20 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/nme.1620351006
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    Paper (German National Licenses)
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