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341.
Karel Holub 《Studia Geophysica et Geodaetica》1999,43(2):147-162
The relation between the number of seismic events N and their magnitude and/or energetic magnitude is one of the basic relations in the statistics of earthquakes and mining-induced events. A detailed analysis of the b-values in the relation log N =a–b logE for the induced seismic events occurring in the Ostrava-Karviná Coal Basin is given in this paper. The least-squares method, as well as the maximum likelihood method were applied in solving this problem mathematically. Based on the results of frequency-energy distribution analysis, it was proved that the variations of b-values in space and time do exist, and that these values are inversely proportional to the level of induced seismicity influenced by the various mining activities being carried out in-situ. This statement could, in general, be supported by the fact that lower b-values correspond to higher seismic activity, while higher b-values correspond to low and moderate seismic activity. 相似文献
342.
D. Perner T. Arnold J. Crowley T. Klüpfel M. Martinez R. Seuwen 《Journal of Atmospheric Chemistry》1999,34(1):9-20
Chemical amplification, CA, a method commonly used for the detection of peroxy radicals, HO2 and RO2, was found to be sensitive towards ClOx (Cl+ClO+OClO) as well. ClOx is reduced by NO to Cl atoms which react with carbon monoxide in the presence of O2. The reaction sequence thus initiated oxidizes CO to CO2 and NO to NO2, with a chain length of 300 ± 60. This allows the atmospheric ClOx content to be measured under ambient conditions with a detection limit of better than 1 ppt. In parallel peroxy radicals are indicated with a chain length of 160 ± 15. Chemical amplification is not specific and does not indicate which radical chain it is seeing. Identification relies solely on plausibility. During the ARCtic Tropospheric Ozone Chemistry (ARCTOC) campaign in spring 1995 and 1996 the CA technique was used at Ny-Ålesund. ClOx at mixing ratios of up to 2 ppt were found in the boundary layer under certain conditions. The low concentrations of ClOx indicate that the arctic boundary ozone depletion is mainly driven by bromine. 相似文献
343.
Ondřej Pejcha David Motl Miloslav Zejda Karel Koss Jitka KudrnÁčovÁ Petr HÁjek Ladislav Šmelcer Pavol A. Dubovský Eva ŠafÁřovÁ Marek Wolf 《Astrophysics and Space Science》2005,296(1-4):285-288
We present ephemerides and solutions of one Algol-type (KZ Dra) and two overcontact systems (LR Cam and IM Vul) based on V(RI)C CCD observations obtained in the project Prosper (network of amateur observers). 相似文献
344.
Karel A. van der Hucht 《Astrophysics and Space Science》2002,281(1-2):199-202
The recent VIIth Catalogue of Galactic Wolf-Rayet Stars lists 227 Population I WR stars, comprising 127 WN, 87 WC, 10 WN/WC and 3 WO stars. Additional discoveries bring the census
to 234 WR stars. A re-determination of the optical photometric distances and the galactic distribution of WR stars shows in
the solar neighbourhood a projected surface density of 2.7 WR stars per kpc2, a N
WC/N
WN number ratio of 1.3, and a WR binary frequency of 40 %.The galactocentric distance (R
WR) distribution per subtype showsR
WN and R
WC decreasing with WN and WC subtypes.
This revised version was published online in September 2006 with corrections to the Cover Date. 相似文献
345.
Summary The paper is concerned with the properties of a density distribution within the Earth. A system of density parameter constraints involving Stokes' coefficients of the gravity field and the parameters describing the Earth's figure is derived. A density model, whose parameters fit these constraints, accounts for the fine structure of the gravity field and Earth's figure. Additional condition imposed on the average spherical density model are derived; they guarantee that the average spherical model is compatible with the 3-D density model.
aamuam ma an¶rt;u nmmu mu u. ¶rt;a uma u, auuau au naam nmm ¶rt;u; uma am m naamaumau n u naam nuau u u. mma ¶rt;, naam m ¶rt;mm mu auuau u, nm n¶rt;um uu umnmau m mmaumau n u u u. ¶rt; ma ¶rt;num u, aa¶rt;au a ¶rt; u ¶rt; nmmu, m nuam ¶rt;uu ¶rt; u ¶rt;u m nmm ¶rt;.相似文献
346.
The largest occurrence of natural metallic iron on Earth is on the island of Disko, Greenland. Metallic iron is found there in a variety of different types, from small metal particles in basalts to large meter-sized blocks. We have studied three different types of metallic iron: small metal spherules (< 300 m) in basaltic magma; larger metal grains (300 m-3 mm), often composed of aggregates of smaller particles, in similar host rocks; and massive iron lumps (up to several tons). Analytical data for 13 siderophile elements in samples from these three types are presented. All metals analysed have a distinctly crustal pattern of siderophile elements. High Co/Ni, Re/Ir or W/Ir ratios clearly demonstrate that a meteoritic origin for the metallic iron must be excluded. Since the Co/Ni and Re/Ir ratios are approximately chondritic in the upper mantle of the Earth, a mantle origin for the Disko metals can also be ruled out. This supports earlier petrological and geological evidence that the metallic iron was formed through reduction of basaltic magma by carbon derived from Tertiary shales and coals. Significant differences in absolute and relative abundances of siderophile elements occur among the three kinds of metals. The strongly siderophile elements (e.g. Ir, Re, Ni) increase in concentration from the small metal spherules through the larger grains to the massive iron lumps. The contents of less strongly siderophile elements (P, W, Ga) decrease in the same sequence. Evidence is presented that the small metal spherules are formed by in situ reduction. Larger iron metal grains and massive iron lumps are composed of small spherules, accumulated by gravitational settling in a magma reservoir. These metal cumulates have extracted highly siderophile elements from a larger volume of basaltic melt.Part of a Ph.D. thesis by W. Klöck 相似文献
347.
Summary Eight models of the ionosphere in the MHD approximation over the whole range of required heights(50–3000 km) are synthesized on the basis of other theoretical studies and a number of empirical methods for the purposes of modelling the ionospheric filtration of the natural micropulsation (Pc1) signal. The models represent a vertically inhomogeneous and dissipative daytime and nighttime ionosphere of higher latitudes in two regions (L=3 and L=5) of the Northern Hemisphere in summer under low (F
10.7
=70) and high (F
10.7
=200) solar activity. The higher ionosphere (h>200 km) is approximated by a quasineutral oxygen-hydrogen plasma(O
+,H
+) taking into account the wave-dissipating effects of the neutral component(O, He). The procedure of computing the physical parameters, locally characterizing the medium of the ionosphere, is demonstrated.
a ¶rt;a mmuu am u a nuuu m¶rt; ¶rt;a um u ¶rt; u ( nuuuu) n a m (50–3000 ), m ¶rt; ¶rt;uau u umauu mm unau (1) uaa. ¶rt;u n¶rt;mam m-¶rt; ¶rt;, na ¶rt; u m u u um ¶rt; am (L=3 u L=5) n, uu nu u, (F 10,7 =70), (F 10,7 =200) amumu. a ua (h>200 ) n¶rt;maa nuuuu auma u¶rt;-¶rt; ¶rt;(O +,H +) na, uau nuuam nu u-a ma maQu(O, He). aa m¶rt; uu uuu naam, m aamuu u ¶rt;.相似文献
348.
Marcela Laštovičková Karel Svoboda Рецензенm A. Janáčková 《Studia Geophysica et Geodaetica》1986,30(2):211-213
au aa ¶rt;a, nuau uuu ma n¶rt; u m muu uu, n¶rt; m¶rt;a nm (). u a m u ¶rt; uuu ma u muuu uuau.
Summary Analysis of the data set describing the chemical composition of the rocks and their electrical parameters was performed by the principal component method. Some relations between chemical composition and electrical parameters were established.相似文献
349.
Summary The paper presents relations experimentally determined between seismic wave amplitudes and the charge size in the immediate vicinity of the shotpoint ( 800 m), on the one hand, and at a more distant station ( 22.5 km), on the other hand. Whereas close to the shotpoint the amplitudes observed sometimes display a considerably degree of scatter, as well as a change in character of the P-wave record due mainly to the change in position of the holes in the area of the shotpoint, this effect was not observed at the more distant station. Since the charge size was changed in the course of the measurements, the observed amplitudes will be reduced to a unified charge size of Q=1,200 kg, according to Eq. (8), in which the exponent n has the following values: nPg=0.77, nSg=0.92 and nLm=1.51. The values of the exponent n for P-waves are very close to the values given in [4–9]. 相似文献
350.
Summary Interpolation and projective methods are compared referring to corrections and or transformations of photogrammetric fields of points. Too many fixed points are needed for a reliable interpolation and, therefore, the interpolation methods are not economical. It is suggested to correct the image coordinates by means of the affine transformation, and the author states that four fiducial marks are sufficient for the transformation if they are placed in the image corners. The relations between the photogrammetric model on one side and the projection of the earth surface and the elevations above sea level on the other side are discussed. 相似文献