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81.
82.
Ohne Zusammenfassung 相似文献
83.
We describe and apply the isobar-hole approach to intermediate energy pion-nucleus reactions. Pion propagation, nucleon and isobar binding, Pauli restrictions and Δ propagation are calculated explicitly within a shell model framework. Intermediate coupling to multihole channels, for example through pion absorption, is treated phenomenologically through an isobar spreading potential. We find strongly collective Δ-hole states, leading to a reformulation of the approach in an extended schematic model. This entails systematic construction of a Δ-hole doorway state basis within which the Δ-hole propagator is evaluated. We find that this doorway space can be truncated at very low dimensionality while preserving accuracy, thereby simplifying the calculations appreciably. We make a detailed comparison between the theoretical results and recent data for π+ — 16O scattering in the pion energy range 50–340 MeV. Nonresonant πN interactions and the π-nucleus Coulomb interaction are included in the calculations. The data is reproduced quite well both below and in the resonance region, and we discuss in detail the role of various dynamical mechanisms. Above the resonance, the calculations are far less successful. We discuss possible shortcomings, stressing the role of inclusive pion-nucleus reactions for revealing the important dynamics. As a test of the Δ spreading potential used for describing elastic scattering, we calculate the total cross section for pion absorption. The result agrees reasonably well with the available data. 相似文献
84.
The thermal expansion coefficient (TEC) of sheet molding compound (SMC) was determined. The experimental determination was accomplished by measuring directly the changes in length of specimens induced by temperature changes. The theoretical derivation was completed by using existing formulae for unidirectional composites and then applying the averaging procedure to obtain the TEC for randomly oriented chopped-fiber composites (SMC).Based on the results of this paper, we observed that SMC tested exhibited strong non-homogeneity and anisotropy. The in-plane TEC was close to that of aluminum, but in the direction normal to the panel was about three times that of aluminum. 相似文献
85.
Ohne ZusammenfassungDie Anregung zu meinem Teil an dieser Arbeit empfing ich im Rahmen eines Forschungsstipendiums. Ich möchte daher der Deutschen Forschungsgemeinschaft auch an dieser Stelle meinen Dank aussprechen. ludwig danzer. 相似文献
86.
Hanfried Lenz 《Archiv der Mathematik》1963,14(1):373-382
Ohne ZusammenfassungHerrnFrank Löbell zum 70. Geburtstag am 11. 5.1963 gewidmet 相似文献
87.
F. Lenz 《Zeitschrift für Physik A Hadrons and Nuclei》1969,222(5):491-503
A method is given to evaluate in a model independent way cross sections for scattering of fast electrons by nuclei. For this purpose the charge distribution in the nucleus will not, as usual, be described by means of the charge densityρ(r), but by the first moment functionT(Q): $$T(Q) = \int\limits_0^Q {r(Q')dQ'} .$$ The integration has to be performed over this part of the charge distribution in which the charge will increase from the value 0 to the valueQ. ThusT(Q) gives the first moment of this part. It will be shown that this function can be fixed by elastic scattering within certain limits. 相似文献
88.
Vincent KA Cracknell JA Clark JR Ludwig M Lenz O Friedrich B Armstrong FA 《Chemical communications (Cambridge, England)》2006,(48):5033-5035
We demonstrate an extreme test of O(2) tolerance for a biological hydrogen-cycling catalyst: the generation of electricity from just 3% H(2) released into still, ambient air using an open fuel cell comprising an anode modified with the unusual hydrogenase from Ralstonia metallidurans CH34, that oxidizes trace H(2) in atmospheric O(2), connected via a film of electrolyte to a cathode modified with the fungal O(2) reductase, laccase. 相似文献
89.
K. Wagner R. Lenz H. Gaedike Regina Müller W. Joachim 《Isotopes in environmental and health studies》2013,49(9-10):338-341
Es werden die Ergebnisse von Mischverfahren für Kohlepulver, Pech und andere Komponenten mitgeteilt, die unter Markierungen mit 24Na-Benzoat im Laboratorium (Mischvolumen etwa 1 Liter) und im Betrieb (Mischvolumen etwa 100 Liter) durchgführt wurden. Die Experimente dienten dem Vergleich der Vergleich der Wirksamkeit verschiedener Mischmaschinen, der Ermittlung optimaler Mischzeiten und der Bestimmung des Verhaltens einzelner Komponenten beim Mischprozeβ. Dis mittels Szintillationszählung gewonnenen Meβwerte werden dabei mit einem Ergebnisdrucker registriert und mit Hilfa einer Rechenanlage mathematisch ausfewertet. 相似文献
90.
Matthias Keller Daniel Lenz Radosław K. Wojciechowski 《Mathematische Zeitschrift》2013,274(3-4):905-932
We study the connections between volume growth, spectral properties and stochastic completeness of locally finite weighted graphs. For a class of graphs with a very weak spherical symmetry we give a condition which implies both stochastic incompleteness and discreteness of the spectrum. We then use these graphs to give some comparison results for both stochastic completeness and estimates on the bottom of the spectrum for general locally finite weighted graphs. 相似文献