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71.
A system of electrons (e) and ions (i) is considered in which beside the Coulomb interaction short range forces are taken into account, i.e. for the e-i interaction a pseudopotential is used, and for the (classical) ions crystallographic radii are used. For a Cesium plasma the thermodynamic properties are calculated quantumstatistically in a wide temperature-density region. Degeneration effects are taken into account approximately. In the region with bound states the ionization equilibrium is discussed, and the Mott-Transition is investigated critically. A phase transition occurs in the framework of the model chosen at Tc ≈ 4500 K and nc ≈ 4.1020 cm?3. 相似文献
72.
73.
E. Meister 《Archive for Rational Mechanics and Analysis》1962,10(1):67-100
Ohne ZusammenfassungDiese Arbeit entstand mit teilweiser Unterstützung des Chief of Research and Development, U.S. Department of the Army, European Office, unter der Vertrags-nummer DA-91-591-EUC-1739, OI-7554-61. 相似文献
74.
75.
E. Meister 《Archive for Rational Mechanics and Analysis》1962,10(1):127-148
Ohne ZusammenfassungDiese Arbeit entstand mit teilweiser Unterstützung des Chief of Research and Development, US Department of the Army, European Office, unter der Vertragsnummer DA-91-591-EUC-1739, OI-7554-61. 相似文献
76.
A novel neutron high resolution double crystal arrangement has been used to measure changes in d-spacing, d-spread and mosaicity through the first order ferroelectric phase transition of DKDP. Coexistence of both para and ferroelectric phases was directly observed in the range Tc to Tc — 3 K. No hysteresis could be detected within the precision of the temperature measurement (10-3K). The origin of the overshoot effect has been elucidated. 相似文献
77.
Mixed boundary value problems for the wave-equation in the x-y-plane, with boundaries parallel to the x-axis, are usually treated by Laplacetransformation. To use this method numerically we present it here by means of the Mikusiński-calculus. In this paper our main interest lies in the treatment of mixed initial-boundary value problems arising in unsteady subsonic cascade flow. 相似文献
78.
A. Fix M. Wirth A. Meister G. Ehret M. Pesch D. Weidauer 《Applied physics. B, Lasers and optics》2002,75(2-3):153-163
A pulsed optical parametric oscillator (OPO) with intracavity sum frequency mixing was developed generating energies of up
to 16 mJ in the 281–293 nm wavelength range. Both OPO process and sum frequency mixing are pumped by the harmonics of a single,
medium-sized Nd:YAG laser. The system is characterized by a high overall efficiency (∼4% conversion from 1064 nm to the UV),
a very compact set-up and stable and reliable operation. This system was successfully employed to measure tropospheric ozone
using the differential absorption lidar (DIAL) technique and shows much promise as a lidar transmitter in airborne case studies
as well as in unattended lidar systems for long-term monitoring. An unattended ozone profiling system could already be successfully
realized.
Received: 1 April 2002 / Revised version: 30 May 2002 / Published online: 2 September 2002
RID="*"
ID="*"Corresponding author. Fax: +49-8153/28-1271, E-mail: Andreas.Fix@dlr.de 相似文献
79.
Meister M Markenroth K Aleksandrov D Aumann T Axelsson L Baumann T Borge MJ Chulkov LV Dostal W Eberlein B Elze TW Emling H Forssén C Geissel H Hellström M Holzmann R Jonson B Kratz JV Kulessa R Leifels Y Leistenschneider A Mukha I Münzenberg G Nickel F Nilsson T Nyman G Richter A Riisager K Scheidenberger C Schrieder G Simon H Tengblad O Zhukov MV 《Physical review letters》2002,88(10):102501
Low-lying resonance states in 7He(6He+n), formed after fragmentation reactions of a 227 MeV/nucleon 8He beam on a carbon target, have been studied. Coincidences between 6He nuclei and neutrons, corresponding to the one-neutron knockout channel in 8He, were selected. The relative energy spectrum in the 6He+n system shows a structure, which is interpreted as the 7He ( Ipi = 3/2(-)) ground state, unbound with 0.43(2) MeV relative to the 6He+n system and a width of Gamma = 0.15(8) MeV overlapping with an excited ( Ipi = 1/2(-)) state observed at 1.0(1) MeV with a width of Gamma = 0.75(8) MeV. 相似文献
80.
In this paper, we describe a novel formulation of a preconditioned BiCGSTAB algorithm for the solution of ill-conditioned linear systems Ax=b. The developed extension enables the control of the residual r
m
=b–Ax
m
of the approximate solution x
m
independent of the specific left, right or two-sided preconditioning technique considered. Thereby, the presented modification does not require any additional computational effort and can be introduced directly into existing computer codes. Furthermore, the proceeding is not restricted to the BiCGSTAB method, hence the strategy can serve as a guideline to extend similar Krylov sub-space methods in the same manner. Based on the presented algorithm, we study the behavior of different preconditioning techniques. We introduce a new physically motivated approach within an implicit finite volume scheme for the system of the Euler equations of gas dynamics which is a typical representative of hyperbolic conservation laws. Thereupon a great variety of realistic flow problems are considered in order to give reliable statements concerning the efficiency and performance of modern preconditioning techniques. 相似文献