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  • 1
    Digitale Medien
    Digitale Medien
    Diffraction by a double grating (1972)
    Springer
    Flow, turbulence and combustion 26 (1972), S. 389-397 
    Details
    ISSN: 1573-1987
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Maschinenbau
    Notizen: Abstract The reflection and transmission of a plane electromagnetic wave by a double grating is investigated. The double grating consists of two mutually parallel, planar arrays of perfectly conducting strips of vanishing thickness. Two types of polarization are investigated, viz.E- and H-polarization. For both types, integral equations for the unknown current densities in the two strips belonging to a single period of the grating, are derived. Subsequently, these integral equations are solved numerically, whereupon the reflection and transmission factors for the different spectral orders are computed.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01897866
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  • 2
    Digitale Medien
    Digitale Medien
    Field analysis and complex resonance frequency of the quasi-TE0,1,1-mode in an inhomogeneously filled resonator with losses (1974)
    Springer
    Flow, turbulence and combustion 29 (1974), S. 137-144 
    Details
    ISSN: 1573-1987
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Maschinenbau
    Notizen: Abstract The object of the present investigation is the determination of the field intensity and the resonance frequency of the quasi-TE0,1,1-mode (with rotational symmetry) in an inhomogeneously filled resonator. The resonator is filled with a number of concentrically located tubes consisting of different materials, which may be lossy. The top and the bottom walls of the resonator are electrically perfectly conducting; at the side wall an impedance boundary condition is employed. Numerical results for a case of practical interest in magnetic resonance experiments are obtained.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00384138
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  • 3
    Digitale Medien
    Digitale Medien
    Diffraction of a plane electromagnetic wave by a slit in a thick screen placed between two different media (1973)
    Springer
    Flow, turbulence and combustion 28 (1973), S. 73-88 
    Details
    ISSN: 1573-1987
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Maschinenbau
    Notizen: Abstract The diffraction pattern due to a plane H-polarized electromagnetic wave is investigated, when this wave is incident upon an infinitely long slit of finite width in an opaque screen of non-vanishing thickness. The screen is located between the plane boundaries of two media with different electromagnetic properties. A Green's function formulation of the problem is employed, leading to a system of four coupled integral equations in which the field distributions in the slit occur as unknowns. Numerical results are presented for the field just below the screen as well as for the far field pattern.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00413058
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  • 4
    Digitale Medien
    Digitale Medien
    Effect of coronary occlusion and reperfusion on local electrical resistivity of myocardium in dogs (1993)
    Springer
    Basic research in cardiology 88 (1993), S. 167-178 
    Details
    ISSN: 1435-1803
    Schlagwort(e): Myocardial electrical resistivity ; electrical anisotropy ; LAD occlusion ; reperfusion ; four electrode technique
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary The effect of coronary occlusion and reperfusion on myocardial electrical resistivity was studied in nine anesthetized open-chest dogs. Anisotropic resistivity was measured on the anterior free wall of the left ventricle (LV) before (control) and during transient occlusion of the left anterior descending (LAD) coronary artery, and during reperfusion. To measure local resistivity longitudinal (RL) and transverse (RT) to epicardial muscle fiber direction, a sensor was developed based on the four electrode (FE) technique with an electrode distance of 1 mm. Previous calculations showed that measurements with this system were confined to a 2-mm-thick epicardial layer. Control values for RL and RT were 243±32Ω·cm and 358±45Δ·cm (mean±SD, n=9) respectively. During a 2-min LAD occlusion, RL increased gradually by 12.4% (p〈0.05) and RT by 7.8% (p〈0.05) above the preceding control values. During a 5-min reperfusion period resistivities returned towards control values, but tended to remain elevated. RL showed a slight initial further increase during the first min of reperfusion and remained significantly above control values during 3 min of reperfusion. RT returned to values not significantly different from control after about 1 min of reperfusion.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00798265
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  • 5
    Digitale Medien
    Digitale Medien
    Change of mechanical properties of rigid poly(vinylchloride) during photochemical ageing (1999)
    Springer
    Journal of materials science 34 (1999), S. 379-384 
    Details
    ISSN: 1573-4803
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Maschinenbau
    Notizen: Abstract Thermally stabilised, unpigmented, rigid PVC samples, were exposed to accelerated photoageing at 40°C, 55°C and 70°C. The concentration profiles of photoproducts were determined on microtome slices (∼ 20 μm) parallel to the irradiated surface using IR (carbonyls) and UV (polyenic double bonds) spectrophotometry and by steric exclusion chromatography (Mn and Mw). They indicate that carbonyls and chain scissions predominate only in a thin superficial layer whereas polyconjugated double bonds and crosslinks predominate in a subcutaneous layer (∼300–400 μm). Tensile measurements show that the ultimate elongation decreases after an induction period whose duration is a decreasing function of temperature. The change of mechanical behaviour can be described in terms of a ductile-brittle transition shift mechanism in which crosslinking plays an important role. A tentative explanation of a such crosslinking induced transition is proposed in the discussion.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1023/A:1004482328203
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  • 6
    Digitale Medien
    Digitale Medien
    A differential-equation method for the computation of the electromagnetic scattering by an inhomogeneity in a cylindrical waveguide (1978)
    Springer
    Journal of engineering mathematics 12 (1978), S. 157-175 
    Details
    ISSN: 1573-2703
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Mathematik , Technik allgemein
    Notizen: Summary In this paper an exact method is described for computing numerically the scattering by an inhomogeneity in a cylindrical waveguide. The “Generalized Telegraphist's Equations” are used to transform the electromagnetic-field equations into a system of ordinary differential equations. The latter system behaves numerically unstable. A method is given to cope with this difficulty. Numerical results are presented for two- and three-dimensional obstacles in a waveguide of rectangular cross-section and they are compared with those obtained by other methods. Our method requires, in general, a relatively small amount of computation time and storage capacity. Another advantage of the method is its flexibility.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00043216
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  • 7
    Digitale Medien
    Digitale Medien
    Computation of electromagnetic fields scattered by a cylindrical inhomogeneity in a homogeneous medium of infinite extent (1979)
    Springer
    Journal of engineering mathematics 13 (1979), S. 107-125 
    Details
    ISSN: 1573-2703
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Mathematik , Technik allgemein
    Notizen: Summary A method is presented for computing time harmonic electromagnetic fields scattered by a cilindrical inhomogeneity in a homogeneous medium of infinite extent. Geometrically, the homogeneity is a cylinder of arbitrary cross-section. Outside a circular cylinder that completely surrounds the inhomogeneity, the electromagnetic field is expanded in terms of wave functions of the circular cylinder. Inside this cylinder, the electromagnetic field equations are transformed into a system of ordinary differential equations in the ‘radial’ direction. The relevant system behaves numerically unstable and is therefore transformed into a stable one through a specific transformation scheme. To elucidate the validity and the versatility of the method, numerical results are presented for fields scattered by a number of different cylindrical inhomogeneities.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00042747
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  • 8
    Digitale Medien
    Digitale Medien
    Mixed Ca/Zn thermal stabilizers for weatherable rigid PVC (1995)
    Brookfield, Conn. : Wiley-Blackwell
    Journal of Vinyl and Additive Technology 1 (1995), S. 5-9 
    Details
    ISSN: 0193-7197
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Maschinenbau , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: Rigid PVC profiles for window frames are required to follow quality standards (usage properties and aging resistance). Our concern is to describe the role of additives and mainly thermal stabilizers on the required properties. Until recently, PVC stabilization was based on heavy metal soaps in the European PVC building industry. Though their resulting efficiency was not questioned, problems of toxicity were raised. Regarding the ecological pressure increase, numerous investigations on co-stabilizers have been carried out in order to improve the performances of mixed Ca/Zn systems. Our results show the properties of rigid profiles stabilized with Ca/Zn systems. First, the extruded profiles properties such as optical (color) and mechanical properties (impact resistance…) are shown. The aging resistance of toxic heavy metal free vinyl formulations is also studied in comparison with typical Pb/Ba/Cd. The performances achieved indicate that an opportunity to move from toxic heavy metallic stabilizers to mixed Ca/Zn systems, resulting, perhaps, in wider development of Ca/Zn stabilizing systems for food packaging and medical plastics.
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/vnl.730010104
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