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61.
Maria Czaja Mariola Kądziołka-Gaweł Radosław Lisiecki Sabina Bodył-Gajowska Zbigniew Mazurak 《Physics and Chemistry of Minerals》2014,41(2):115-126
For the first time ever, the luminescence spectra of Cr3+ centers in two chlorite crystals are presented. Chromium ions occupy the strong crystal-field site M4 in the brucite sheet and the intermediate crystal-field site in the inner octahedral sheet for purple and green chlorite, respectively. We discuss the influence of an effective positive charge on the Cr3+ ion and an effective negative charge of ligands on the differences in the values of the Dq and B parameters. It is concluded that the presence of Fe2+ ions and other point defects, as well as concentration quenching, causes the very short luminescence lifetimes of chromium ions. 相似文献
62.
63.
Periglacial and Fluvial Factors Controlling the Sedimentation of Pleistocene Breccia in NW Poland 下载免费PDF全文
Piotr Weckwerth Małgorzata Pisarska‐Jamroży 《Geografiska Annaler: Series A, Physical Geography》2015,97(2):415-430
Breccias were investigated on the terrace of the Toruń‐Eberswalde ice‐marginal valley at Rozwarzyn (NW Poland). Breccia layers include soft‐sediment clasts with diameters between 2 and 256 mm and soft‐sediment megaclasts with diameters from 256 mm to 7 m. The shape of the soft‐sediment clasts and megaclasts (derived from frozen sediments) in the breccia is diverse: from angular and irregular in the case of debris‐flow breccias to slightly rounded and tabular in fluvial breccias. These two types of breccias were developed during the Late Weichselian when the periglacial climate favored extensive lateral erosion by currents of frozen braided channels in the ice‐marginal valley. The dual presence of breccias of fluvial and debris‐flow origin in channel deposits is unique for Quaternary sediments. Zones of breccias existed in the channels where scours and obstacle marks related to megaclasts developed. The study of breccias shed new light on the fluvial processes in ice‐marginal valleys during the Pleistocene and can be considered as diagnostic for fluvio‐periglacial conditions. 相似文献
64.
65.
Krzysztof Fortuniak Włodzimierz Pawlak Mariusz Siedlecki 《Boundary-Layer Meteorology》2013,146(2):257-276
Atmospheric measurements over 5 years (2005–2010) at two sites in ?ód?, central Poland have been analyzed to develop a better understanding of turbulence in urban areas. Fast response wind velocity, temperature, humidity and CO2 concentration were measured using sonic anemometers and gas analyzers, placed on narrow masts at 37 and 42 m above the ground. The measurements were used to calculate standard deviations of each parameter, and were then normalized according to local Monin–Obukhov similarity theory and plotted as a function of stability parameter ζ = z′/L. Results for the wind components show typical scaling with a power law with exponent ±1/3 in the free convection limit, and that approaches a constant value close to neutral stratification. For stable conditions, the constant value in the neutral limit remains the same for stability parameters lower than 0.1–0.2, then increases. The normalized standard deviation of temperature fits the ?1/3 law in the free convection limit, approaching a constant value within a stable limit. However, it exhibits hyperbolic characteristics for close to neutral stratification. The normalized standard deviations for humidity and CO2 concentration exhibit scaling similar to the wind components in the unstable regime and remain constant in the stable domain. The results for the wind components and for temperature are in the range of various functions found in other studies. The absolute values for humidity and CO2 concentration seem to be slightly higher, but only single examples of such investigations can be found in the literature. 相似文献
66.
Sławomir Breiter 《Celestial Mechanics and Dynamical Astronomy》1997,67(3):237-249
The analytical solution for the perturbations of an artificial satellite due to the zonal part of the geopotential is presented.
The Hamiltonian is fully normalized up to the second order by a single averaging transformation and the generating function
is given explicitly. The formulas allow an arbitrarily high degree of geopotential harmonics to be included. The transformation
from mean to osculating variables or vice versa is performed by means of a numerical method proposed by the author in a previous
paper (Breiter,1997): periodic perturbations are computed by means of a Runge-Kutta method of order 2 instead of being explicitly
derived from a generator.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
67.
Michał Siwak 《Astrophysics and Space Science》2005,296(1-4):289-292
In this paper we investigate a sample of contact eclipsing binary systems, which exhibit a large temperature difference (at
least 1000 K) between the components. Considering the effective temperature of the primary star, the systems were divided
into three groups. We applied a Monte Carlo method as a more suitable procedure for the search of the system configurations
previously known as contact binaries with a large temperature difference and with a negligible value of the filling factor.
Using only data presented in the literature, we found that the geometrical configuration of almost all systems from the second
group is near-contact rather than contact. 相似文献
68.
We discuss Arp's hypothesis that the HII regions are more numerous and more conspicuous on the side of a galaxy facing its companion. Arp's hypothesis seems not to be true if we add to Hodge's sets of galaxies only the most probably tidally-interacting cases. 相似文献
69.
Wiesław Betkowski 《Astrophysics and Space Science》1980,70(1):243-245
In this paper we discuss a hierarchical model of Universe which was proposed by Wesson (1975). We assert that the mathematical formalism used by Wesson leads to contradiction with Einstein's equations. 相似文献
70.
S.B. Lyakhov A.D. Maiorov G.G. Managadze O.A. Povalyaev A.I. Chmil L.Yu. Kochmarev E.G. Shustin M.F. Friedrich W.K. Riedler A.N. Laliashvili A. Kiraga Z. Kłoss Z. Kravchic N.A. Leonov 《Planetary and Space Science》1982,30(4):347-357
Laboratory results of beam plasma discharge (BPD) (dimensions several metres) in a homogeneous atmosphere and a jet of neutral gas are presented. The beam was obtained by an electron gun of the same type as used in rocket experiments.The BPD parameters glow intensity, electromagnetic field and its spectrum, electron density as well as the flux of scattered electrons were measured. In addition, photographs of the BPD were taken. The threshold of BPD ignition was determined as a function of gas pressure and beam parameters. The initial stage of BPD formation as well as various types of oscillatory processes in the discharge were studied. A possible process of BPD initiation is presented. 相似文献