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991.
T. Jaravel O. Dounia Q. Malé O. Vermorel 《Proceedings of the Combustion Institute》2021,38(3):3529-3536
In the context of vapour cloud explosion, the flame acceleration process can lead to conditions promoting deflagration to detonation transition (DDT), potentially leading to increased damages in accidental scenarios. This study focuses on this phenomenon by performing simulations of detonation reinitiation for fast flames in the Chapman–Jouguet deflagration regime. It is obtained experimentally by the attenuation of an incident detonation by an array of obstacles. A primary objective of the paper is to demonstrate the ability of the numerical model to reproduce the major experimental trends, namely the variation of the reinitiation propensity for different initial pressures and blockage ratios (BRs). Chemical explosive mode analysis (CEMA) is also adapted to the context of this study, in order to identify locally the propagation regime and to provide insights on the reinitiation mechanism. An a priori validation of the CEMA methodology is first performed on relevant canonical one-dimensional configurations. Subsequently, ensembles of five realizations are computed at different initial pressures and BRs and compared to experimental data. They are shown to reproduce the major observed trends in terms of detonation reinitiation length with respect to the operating conditions, with significant variability from one realization to another. In addition, the reinitiation mechanism is also found to be consistent with experimental observations and a previous numerical study of the same configuration. The CEMA methodology adapted to this context is able to identify locally the different propagation regimes, and to track the highly reactive zones that coherently couple with transverse pressure perturbations, leading to the formation of a strongly reacting kernel which eventually triggers the detonation reinitiation. 相似文献
992.
We conduct extensive research into the structures of BexZn1-xOO ternary alloys in a pressure range of 0-60GPa,using the ab initio total energy evolutionary algorithm and total energy calculations,finding several metastable structures.Our pressure-composition phase diagram is constructed using the enthalpy results.In addition,we calculate the electronic structures of the BexZn1-xOO structures and investigate the bandgap values at varying pressures and Be content.The calculated results show that the bandgap of the BexZn1-xOO ternary alloys increases with an increase in Be content at the same pressure.Moreover,the bandgap of the BexZn1-xOO ternary alloys increases with the increasing pressure with fixed Be content.At the same Be content,the formation enthalpy of the BexZn1-xOO ternary alloys first decreases,then increases with the increasing pressure. 相似文献
993.
994.
For any (super)group and hence for any geometrical (super)theory Bianchi identities imply that certain 3-forms vanish. In order to perform a systematic analysis of their implications in the presence of constraints one needs a complete basis of independent 3-forms spanning the 3-form linear space. In this paper we discuss a general procedure for the derivation of such a basis in the case of supersymmetric theories involving commuting spinor 1-forms. Our technique is based on the decomposition of the product of group representations into irreducible components and replaces all Fierz rearrangements. We give as examples the cases of N = 1, d = 4, N = 2, d = 4 and N = 2, d = 5 supergravity. Then applying our algebraic techniques to the last of these three models, the only other known example, besides N = 1, d = 4 supergravity, of a pure geometrical theory, we derive its off-shell structure containing 48 bosons and 48 fermions. The torsion-like constraints which we implement in the Bianchis in order to obtain our set of auxiliary fields are a subset of the complete set of variational equations of the theory so that we derive our off-shell multiplet without any reference to an embedding conformal symmetry. The point with which we still need to use ingenuity is the selection of those equations which are to be kept and those which are to be thrown out. 相似文献
995.
Aldée Cabana Yves Doucet Jean-Marc Garneau Claude Pépin Pascal Puget 《Journal of Molecular Spectroscopy》1982,96(2):342-350
The vibration-rotation bands 2ν1, 2ν3, ν1 + ν2, ν2 + ν3, and ν1 - ν2 of H12CP were recorded and analyzed. These data were combined with previously reported results for this molecule to obtain an improved and extended set of vibrational and rotational constants. All xij and γij were calculated except those that require data from a summation band involving ν1 and ν3. 相似文献
996.
The response of damped linear finite systems (discrete and continuous) to harmonic, stationary random, and transient excitations is studied. The assumed damping may be light or heavy, viscous and/or hysteretic (the latter being frequency-independent or frequency-dependent), and proportionally or non-proportionally distributed over the structure. Closed-form analytic transfer functions are derived for beam systems. In order to rationalize subsequent numerical calculations, the transfer functions are approximated by using truncated series. Complex eigenfrequencies of the structure and complex residues of the actual transfer function are used. Special interest is paid to the mathematical modelling of experimentally measured damping. Causality requirements are considered. Numerical examples are given. An efficient method (by which aliasing is eliminated) for numerical Fourier transformation has been developed and applied. 相似文献
997.
M. Aguilar G. J. Rubio O. F.J. López J. Garciá-Solé H.S. Murrieta 《Solid State Communications》1982,44(2):141-144
Europium precipitation in monocrystalline KBR has been studied using optical absorption and photoluminescence techniques. The annealing of quenched samples at temperatures below 100°C produces the growth of an emission band peaking at 433 nm which appears to be related with the presence of Suzuki-type precipitates in the crystals. The aging at higher temperatures, however, produces the appearence in the emission spectrum of two other bands peaking at 427 and 459 nm. The data presented in this paper strongly suggest that the former band is associated with the stable dihalide phase EuBr2 in the host KBr, while the latter is due to a metastable precipitate whose structure appears to be quite similar to that of europium bromide. Some of the characteristics of the second phase precipitates were obtained by measuring the crystal field splitting (10 Dq) of the 4f65d configuration of the Eu2+ ions in each one of them. 相似文献
998.
Andre S. Barci V. Barneoud D. Beraud R. Charvet A. Samman H. El Genevey J. Gizon A. Gizon J. Kossakowski R. Tréherne J. Weiss B. 《Zeitschrift für Physik A Hadrons and Nuclei》1982,308(2):181-182
Preliminary results on residual nuclei production in 30 MeV/A12C interaction with medium heavy targets are presented. Gamma-ray spectroscopic techniques were used. Evidence for charge and angular momentum transfer is found.
相似文献999.
B. Balestri P. Y. Bertin B. Coupat G. Fournier A. Gérard E. W. A. Lingemann J. Miller J. Picard B. Saghai K. K. Seth P. Vernin 《Czechoslovak Journal of Physics》1982,32(3):255-257
Elastic scattering differential cross section data of
±
d at 65 MeV and
±
4He at 51 MeV are presented and compared respectively to fully relativistic 3-body and optical potential calculations including true pion absorption.Presented at the symposium Mesons and Light Nuclei, Liblice, Czechoslovakia, June 1981. 相似文献
1000.
V. Brabec M. Ryšavý O. Dragoun M. Fišer A. Kovalík Cs. Ujhelyi D. Berényi 《Zeitschrift für Physik A Hadrons and Nuclei》1982,306(4):347-351
The relative conversion line intensities of the 35 keV transition in125Te were measured using the 50 cm π√2 iron-yoke magnetic spectrometer. The transition was proved to be ofM1+(8.7±1.5)×10?4 E2 multipolarity, the magnetic component being affected by the nuclear structure with λ=2.4±1.4. The conversion intensity ratio,0/N 1 , was determined to be 0.115+0.005 for both Ag125 I and Cu125 I sources. It is in accordance with previous measurements for the Zn125m Te and Pb125m Te sources and differs from those for the125mTeO2 and Na2H 4 125m TeO6 ones. The conversion coefficients were calculated for 32 configurations of the valence shell of free tellurium atom and ions and were compared with the experimental results. 相似文献