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71.
72.
T. C. Awes C. Barlag F. Berger M. A. Bloomer C. Blume D. Bock R. Bock E. -M. Bohne D. Bucher A. Claussen G. Clewing L. Dragon A. Eklund S. Garpman R. Glasow H. Gustafsson H. H. Gutbrod G. Hölker J. Idh P. Jacobs K. H. Kampert B. W. Kolb H. Löhner I. Lund F. E. Obenshain A. Oskarsson I. Otterlund T. Peitzmann F. Plasil A. M. Poskanzer M. Purschke B. Roters S. Saini R. Santo H. R. Schmidt S. P. Sørensen K. Steffens P. Steinhaeuser E. Stenlund D. Stüken G. R. Young 《Zeitschrift fur Physik C Particles and Fields》1995,65(2):207-213
Correlations between protons are studied in the target fragmentation region of reactions of protons and16O with C, Cu, Ag, Au and of32S with Al and Au at 200A GeV. The emitted protons were measured with the Plastic Ball detector in the WA80 experiment at the CERN SPS. The comparison of the correlation function with calculations, assuming a spherical, gaussian shaped source with a lifetime τ=0 fm/c, allows the extraction of radius parameters. The values are very close to those expected from the geometry of the target nuclei and increase with the target mass as αA Target 1/3 . Even in proton induced reactions the whole target nucleus is involved. The dependence of the radii on centrality, polar angleθ lab, and energy, and their relation to measured proton yields are presented. 相似文献
73.
The Lagrangian smoothed particle hydrodynamics (SPH) method is used to simulate shock waves in inviscid, supersonic (compressible) flow. It is shown for the first time that the fully Lagrangian SPH particle method, without auxiliary grid, can be used to simulate shock waves in compressible flow. The wall boundary condition is treated with ghost particles combined with a suitable repulsive potential function, whilst corners are treated by a novel ‘angle sweep’ technique. The method gives accurate predictions of the flow field and of the shock angle as compared with the analytical solution. The study shows that SPH is a good potential candidate to solve complex aerodynamic problems, including those involving rarefied flows, such as atmospheric re‐entry. Copyright © 2016 John Wiley & Sons, Ltd. 相似文献
74.
75.
R. Albrecht T. C. Awes P. Beckmann F. Berger M. A. Bloomer D. Bock R. Bock G. Claesson G. Clewing L. Dragon A. Eklund R. L. Ferguson A. Franz S. Garpman R. Glasow H. Å. Gustafsson H. H. Gutbrod M. Hartig G. Hölker J. Idh P. Jacobs K. H. Kampert B. W. Kolb P. Kristiansson H. Löhner I. Lund F. E. Obenshain A. Oskarsson I. Otterlund T. Peitzmann S. Persson F. Plasil A. M. Poskanzer M. Purschke H. G. Ritter B. Roters S. Saini R. Santo H. R. Schmidt R. Schmidt S. P. Sørensen K. Steffens P. Steinhauser E. Stenlund D. Stüken M. L. Tincknell A. Twyhues G. R. Young 《Zeitschrift fur Physik C Particles and Fields》1992,53(2):225-237
Correlations between positive pions are investigated in the target fragmentation region of 200A GeV16O+nucleus collisions. The pions are measured with the Plastic Ball detector in the WA80 experiment at the CERN SPS. The target mass dependence of the radii and the correlation strength extracted by interferometry is studied. A new approach to the fit of the correlation function is introduced. The correlation strength and both invariant and transverse radii increase with decreasing target mass. The transverse radius for16O+C reactions appears to be much larger than the geometrical radius of the nuclei involved. For the Au target only a small fraction of the measured pions contributes to the apparent correlation. Hints for a much larger second component in16O+Au reactions are observed. Rescattering phenomena may provide a clue to understand these phenomena. 相似文献
76.
A M Eklund J E Berg I Wahlberg 《Acta chemica Scandinavica (Copenhagen, Denmark : 1989)》1992,46(4):367-371
A new diterpenoid containing a rare carbobicyclic cembrane-derived skeleton, the capnosane skeleton, has been isolated from flowers of Greek tobacco. It has been identified as (1S*,3R*,4S*,6R*,7R*,8R*,11Z)-4,6,8-trihydroxy-11-capnosene- 2,10-dione by spectral methods and X-ray analysis of the corresponding benzoate. A full account of the X-ray work is given. 相似文献
77.
We analyze a field experiment where ambient air is injected into the soil during the summer and extracted again during the winter. A multiphase model accounting for the conductive transport as well as the convective transport with the moving liquid and gas phases is used along with a more simplified single-phase model where the convective transport is due to the gas alone. The latter model also accounts for subzero wintertime temperatures. The multiphase model captures well both the seasonal variations and the actual test sequence, the main calibration being in the adjustment of medium permeabilities based on the observed pressure responses. The effect of the injection pump on the temperature and humidity of the injection air needs to be known accurately. Taking into account the humidity of the injection air explicitly instead of using humidity-corrected enthalpy values also has an effect. The effect of various humidity and specific enthalpy assumptions is of the order of 1–1.5°C, while ignoring the wintertime subzero temperatures has an effect of 1–2°C. These differences are of the same order of magnitude as the heterogeneity-introduced differences in field data. Using the simplified single-phase model typically appears to cause a difference of 1–2°C, but can yield an even higher deviation of the order of 3–4°C. 相似文献
78.
The boundary element spline collocation method is studied for the time-fractional diffusion equation in a bounded two-dimensional
domain. We represent the solution as the single layer potential which leads to a Volterra integral equation of the first kind.
We discretize the boundary integral equation with the spline collocation method on uniform meshes both in spatial and time
variables. In the stability analysis we utilize the Fourier analysis technique developed for anisotropic pseudodifferential
equations. We prove that the collocation solution is quasi-optimal under some stability condition for the mesh parameters.
We have to assume that the mesh parameter in time satisfies
(ht=c h\frac2a)(h_t=c h^{\frac{2}{\alpha}}), where (h) is the spatial mesh parameter. 相似文献
79.
A.M. Rao P.C. Eklund U.D. Venkateswaran J. Tucker M.A. Duncan G.M. Bendele P.W. Stephens J.-L. Hodeau L. Marques M. Núñez-Regueiro I.O. Bashkin E.G. Ponyatovsky A.P. Morovsky 《Applied Physics A: Materials Science & Processing》1997,64(3):231-2239
60 polymers. Pure and mixed phase polymeric samples were synthesized by simultaneously subjecting microcrystalline C60 powder or pellets to various pressures () and temperatures (). The optical spectra of the orthorhombic, tetragonal, and rhombohedral C60 polymer phases are observed to be quite distinct and rich. These spectra exhibit numerous lines and an overall downshift
in frequency relative to C60 is observed, consistent with a loss of double bonds from the fullerene cage. The LDMS spectra of a sample synthesized at
under hydrostatic conditions and , exhibited a succession of clear peaks at mass numbers corresponding to , similar to the LDMS data on the C60 photopolymer. This is taken as further evidence for interfullerene bonds in these high-pressure polymers. The XRD pattern
of this sample indicates the presence of a strong texture in the sample.
Received: 14 November 1996/Accepted: 8 January 1997 相似文献
80.
Jyrki K. Kauppinen Ilkka K. Salomaa Jari O. Partanen Matti R. Hollberg 《Optical Review》1997,4(2):293-296
The carousel interferometer is a new type of an interferometer, which has been invented at the University of Turku. It consists of a beamsplitter and five plane mirrors. Four of the mirrors are mounted on a carousel, which rotates back and forth. We have modified the interferometer for use in the Fourier-transform ultraviolet (FT-UV) spectroscopy. Test measurement with plasma radiation gives favourable results. The most important property, which makes the carousel interferometer suitable for UV measurements, is its good stability in modulation.Presented at 1996 International Workshop on Interferometry (IWI ‘96), August 27–29, Saitama, Japan. 相似文献