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21.
In order to evaluate the material composition of Ultra High Performance Concrete (UHPC), material properties such as dynamic tensile strength or fracture strength and also the fracture energy under impact loading are of significant importance. The use of a modified Hopkinson Bar enables the determination of the required data. On the basis of experimental investigations our contribution deals with the numerical finite element simulation of the Hopkinson Bar test. The propagation of stress waves is reproduced by means of a special time-integration scheme. We simulate the propagation of cracks by using adaptive cohesive elements including a corresponding separation law. The critical energy release rate (Griffith-energy) is calculated and compared to the values determined by experimental results. (© 2014 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
22.
Felix Weinberg Fred Carleton Dhiren Kara Agatha Xavier Derek Dunn-Rankin Matthew Rickard 《Experiments in fluids》2006,40(2):231-237
Air induction and rotation about the axis of a vertical tube is generated by an assembly of corona discharges between pinpoints
and earthed electrodes, which induces a swirling ionic wind. The mechanism is elucidated and the geometrical configuration
of the electric field lines of force is optimised by studying the deposition of charged particles on the earth electrodes,
by numerical modelling of a simplified geometry and ultimately by maximising the measured tangential velocities. Upward convective
flows of up to a litre per second are provided by an additional ionic wind pump at the base of the tube. With assemblies of
up to three layers of six points each, tangential velocities of up to 3.3 m/s (≈900 rpm) are attained at the periphery, as
recorded by small Pitot tubes. The concept, developed particularly for microgravity environments, appears suitable for adding
a substantial centrifugal contribution to the operation of electrostatic precipitators and as a basis for further progress
on electrical field-controlled burners. 相似文献
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Towards a simple and robust model for void-based fatigue prediction, we investigate the interaction of voids with its surrounding by using a multi-field method. We couple the concentration fields of tin c1 and lead c2 with an additional field c3, where the latter is assigned with a void field. The interaction potential manifests three stable states. Two are obtained by experimental results of tin-lead (SnPb) and the void stable state is postulated by construction. The logarithmic form of the thermodynamically consistent configurational entropy is approximated within this study by a fourth order polynom. It has been shown that the interfacial energy coefficient is independent of void's size, but rather depends numerically on the mesh size, which is used in the model presented here. Both governing equations follows a Cahn-Hilliard-type equation to mimic the microstructural changes. (© 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
25.
Deglint E Martens H Edwards E Boon N Dance P Weinberg N 《Physical chemistry chemical physics : PCCP》2011,13(2):438-440
We propose a novel approach toward calculating activation and reaction volumes based on MD simulations of reaction systems. The accuracy of the calculated volumes, verified by the comparison to the experimental data, is suitable for quantitative analysis of the experimental volumes of activations in terms of structural parameters of the corresponding transition states. 相似文献
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27.
Franz Weinberg 《Zeitschrift für Angewandte Mathematik und Physik (ZAMP)》1979,30(4):677-698
An algorithm is developed for the sequential determination of the coefficients of a generalized linear Diophantine constraint which is equivalent to a given system of generalized linear Diophantine constraints.
Zusammenfassung Ein Algorithmus wird entwickelt für die sequentielle Bestimmung der Koeffizienten einer verallgemeinerten linearen Diophantischen Restriktion, die einem vorgelegten System verallgemeinerter linearer Diophantischer Restriktionen äquivalent ist.相似文献
28.
E. H. Pinnington P. Weinberg W. Verfuß H. O. Lutz 《Zeitschrift für Physik A Hadrons and Nuclei》1977,281(4):325-332
A new experimental arrangement is described which is designed for measuring lifetimes of levels of low ionization states of heavy elements using the beam-foil technique. The method is applied to obtain lifetimes of 14 CoI transitions in the spectral range 3000 Å to 3950 Å. Our results are found to be in excellent agreement with the lifetime of the levels which have been measured previously using dye-laser excitation. Thef-values derived from our results indicate that the temperature correction proposed by Degenkolb and Griffiths greatly improves the accuracy of the Corliss and Bozman data, and also show remarkable consistency with the semi-empirical values tabulated by Kurucz and Peytremann. Finally, our newf-values are used to obtain a cobalt photospheric abundance given by logN(Co)=4.75±0.05. 相似文献
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