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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Applied physics 24 (1981), S. 225-228 
    ISSN: 1432-0630
    Keywords: 51 ; 84
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract The observation of a large number of particle trajectories in a transversi single wire HGMS has made possible the experimental determination of the critical capture radius. Both the trajectories and the capture radius were found to be in good agreement with calculated values obtained by numerical means using a laminar flow model.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1432-0630
    Keywords: 85.70 ; 41
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract A model for the description of saturation buildup curves on single-capture elements is presented. It avoids the principal difficulties connected with the so-called SEB model in the case of the transverse HGMS-geometry. The basic idea of this model consists of the “linking” of the normal and tangential components of the forces acting at the buildup surface by a force of static friction. In contrast to the SEB-model the fact that the saturation buildup surface is neither circular nor concentric with the cross section of the capture element is taken into account. After evaluating two sets of experimental data and calculating the coefficient of static frictionf the “model of static friction” is submitted to a first examination. Within the accuracy of these preliminary measurements and even with an approximate evaluation of the fluid drag force the usefulness of the proposed method is established.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Applied physics 42 (1987), S. 117-124 
    ISSN: 1432-0630
    Keywords: 85.70 ; 41
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract An experimental investigation of particle accumulation on a single wire in the transverse HGMS configuration is presented. For saturation buildup we obtain a monotonic decrease of the coefficient of static frictionf sat with the flow velocityv a on the basis of the “friction model”. The power law of the dependence of the saturation accumulation area onv a , predicted by this model, is experimentally verified. Furthermore, we present an empirical law describing the dependence of the accumulation area on timeτ and on flow velocityv a for the entire buildup process. From the investigation of the initial accumulation we conclude that existing theories of the so-called capture radius do not satisfactorily describe the situation near the end of a capture wire.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1432-0630
    Keywords: 51 ; 84
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract The trajectories of para-and ferromagnetic particles with velocities between 0.04 and 2.5 cm s−1 have been investigated in an HGMS model system with axial configuration. A single-wire system has been observed by a TV system. The trajectories were compared with the ideal (inviscid flow) and laminar (viscous flow) model. The results agree with laminar flow model.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Angewandte Chemie International Edition in English 12 (1973), S. 819-835 
    ISSN: 0570-0833
    Keywords: Allyl cations ; Cyclization ; Cyclopentanes ; Cycloaddition ; Cycloheptanes ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The cycloaddition of allyl cations to conjugated dienes offers an efficient and general tool for the construction of seven-membered carbocycles. The silver salt route is highly suitable for generating allyl cations and can be used even in most difficult cases, i. e. for elusive and intractable allyl cations such as 2-methylallyl, 2-methoxyallyl, and the parent allyl cation. Cycloadditions to the 2-methoxyallyl cation come very close to the prototype of a 6π, 7C reaction, since the carbonyl group introduced into the new ring can either be used for further transformations or be removed altogether. The combination of an allyl cation with π reactants, especially conjugated dienes, is a powerful and strongly convergent synthetic method since it permits one-step assembly, from a C3 and a C4 unit, of a cluster of up to four chiral centers in a ring which is larger than six-membered. Allyl cations combine with electron-rich 2π systems to form novel five-membered rings. The nature of the organometallic intermediates has been elucidated in many cases.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Angewandte Chemie International Edition in English 23 (1984), S. 1-19 
    ISSN: 0570-0833
    Keywords: Cycloaddition ; Allyl cations ; Cations ; Synthetic methods ; Cycloheptanes ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The reaction of allyl cations and 1,3-dienes affords seven-, five-, and six -membered rings as well as products of electrophilic substitution and linear 1:1-adducts. In this review article, preparative and mechanistic advances are summarized with special emphasis on the synthesis of seven-membered carbocycles. For the first time, a comprehensive mechanistic description is presented: Three classes A, B, and C correlate product type and stereochemistry with the nucleophilicity of the diene, the electrophilicity of the allyl cation intermediate, and the donor capacity of the group Y attached to the central carbon of the allylic moiety. The problem “allylic resonance versus nucleophilic participation of Y” is discussed and experimental evidence is adduced for some participation of Y as a function of its nucleophilicity. For cyclopentenyl cations, enhanced charge separation and electrophilicity are postulated, even when Y is a good donor, due to the structurally enforced polarity of the π-allyl system.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
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