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311.
312.
Dominik Fleitmann Stephen J. Burns Marek Pekala Augusto Mangini Abdulkarim Al-Subbary Mohammad Al-Aowah Jan Kramers Albert Matter 《Quaternary Science Reviews》2011,30(7-8):783-787
Arabia is an important potential pathway for the dispersal of Homo sapiens (“out of Africa”). Yet, because of its arid to hyper-arid climate humans could only migrate across southern Arabia during pluvial periods when environmental conditions were favorable. However, knowledge on the timing of Arabian pluvial periods prior to the Holocene is mainly based on a single and possibly incomplete speleothem record from Hoti Cave in Northern Oman. Additional terrestrial records from the Arabian Peninsula are needed to confirm the Hoti Cave record. Here we present a new speleothem record from Mukalla Cave in southern Yemen. The Mukalla Cave and Hoti Cave records clearly reveal that speleothems growth occurred solely during peak interglacial periods, corresponding to Marine Isotope Stages (MIS) 1 (early to mid-Holocene), 5.1, 5.3, 5.5 (Eemian), 7.1, 7.5 and 9. Of these humid periods, highest precipitation occurred during MIS 5.5 and lowest during early to middle Holocene. 相似文献
313.
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
314.
Marek Grad 《Geophysical Journal International》1984,79(1):353-361
Summary. The paper presents the results of modelling of diffracted and reflected-diffracted waves in fracture zones. The Berryhill method was used and the calculations were made for a profile perpendicular to the diffracting edge. Several homogeneous models of the Earth's crust, characterized by different values of crustal thickness, velocity and horizontal distance between shot point and diffracting edge were considered. A dependence of the relative amplitude of diffracted waves on the location of the diffracting edge is given. The pattern of the seismic wavefield depends upon the dimensions of the fracture zone. Amplitude curves of reflected-diffracted waves are presented for a series of models of fracture zones. The possibility of applying the amplitudes of reflected-diffracted wave trains to the interpretation of the structure of fracture zones in the Earth's crust is andysed for different types of fracture zones. 相似文献
315.
Danuta Peryt 《地学学报》2013,25(4):298-306
Benthic and planktonic foraminifera from a marly clay intercalation sandwiched between mid‐Badenian (Middle Miocene) gypsum deposited in an environment of an evaporitic shoal (<1 m deep) at Borków (southern Poland) indicate a major marine flooding event in the previously isolated Carpathian Foredeep Basin (Central Paratethys). After this very short‐term environmental change, benthic foraminifers started to colonize a new niche which was previously defaunated, and the pattern of benthic foraminiferal colonization is similar to that related to the reflooding which terminated the Badenian evaporite deposition. The benthic foraminifer assemblages are composed of pioneer, opportunistic, r‐selected species dominated by elphidiids. The connection of the Carpathian Foredeep Basin with the marine reservoir was short‐lived. The marly clay intercalations in evaporite sequences originating in bared basins can thus register major environmental changes. 相似文献
316.
Andrzej A. Zdziarski Marek Gierliski A. R. Rao S. V. Vadawale Joanna Mikoajewska 《Monthly notices of the Royal Astronomical Society》2005,360(3):825-838
We present an exhaustive analysis of five broad-band observations of GRS 1915+105 in two variability states, χ and ω, observed simultaneously by the Proportional Counter Array (PCA) and High-Energy X-ray Timing Experiment (HEXTE) detectors aboard the Rossi X-ray Timing Explorer , and the Oriented Scintillation Spectrometer Experiment (OSSE) detector aboard the Compton Gamma-ray Observatory . We find all the spectra well fitted by Comptonization of disc blackbody photons, with very strong evidence for the presence of a non-thermal electron component in the Comptonizing plasma. Both the energy and the power spectra in the χ state are typical of the very high/intermediate state of black hole binaries. The spectrum of the ω state is characterized by a strong blackbody component Comptonized by thermal electrons and a weak non-thermal tail. We then calculate rms spectra (fractional variability as functions of energy) for the PCA data. We accurately model the rms spectra by coherent superposition of variability in the components implied by the spectral fits, namely a less variable blackbody and more variable Comptonization. The latter dominates at high energies, resulting in a flattening of the rms at high energies in most of the data. This is also the case for the spectra of the quasi-periodic oscillations present in the χ state. Then, some of our data require a radial dependence of the rms of the disc blackbody. We also study the distance to the source, and find d ≃ 11 kpc as the most likely value, contrary to a recent claim of a much lower value. 相似文献
317.
Tadeusz Wyrzykowski 《Journal of Geodynamics》1987,8(2-4)
A new determination of recent vertical movements of the Earth's crust in Poland is described in this paper. It resulted from the joint adjustment of the network of repeated levelling in 7 countries of Eastern and Central Europe. The author presents the characteristics of the levelling data sets used (measurements made in 1953–1957 and 1974–1979), results of the repeated levelling, the method of determination of the recent crustal movements and of the preparation of the map at a scale of 1:2.500.000 presenting these movements for the area of the whole country. The results of the determination of the Earth's crustal movements are discussed, and causes of the prevailing appearance of sinking movements are suggested. Differences between the values of vertical movements of the Earth's crust obtained during various determinations are presented, as well as the maximum mean error of the difference between new and old determinations. The conformity of these determinations is assessed. 相似文献
318.
Some numerical urban boundary-layer studies 总被引:2,自引:0,他引:2
Two types of models, describing respectively the thermal and the dynamic structure of the urban boundary layer are presented. The influence of density and height of urban buildings, urban traffic, man-made heat flux, changes of albedo and existence of an aerosol layer are tested. The models give a possibility of explaining the influence of selected factors on the atmospheric state over an urban area.On sabbatical at Meteorological Department, University Uppsala, Sweden. 相似文献
319.
Influence of vertical ground motion on seismic-induced displacements of gravity structures 总被引:1,自引:0,他引:1
Andrzej Sawicki Wodzimierz Chybicki Marek Kulczykowski 《Computers and Geotechnics》2007,34(6):485-497
A method enabling assessment of seismic-induced movements of gravity block is proposed. This method is based on dynamic analysis of the block subjected to both horizontal and vertical ground accelerations, and resultant forces acting on the block. There are two kinds of the motion. The first one is trivial, as it is a common motion of the block and subsoil. The second is a relative motion of the block with respect to subsoil, depending on combination of ground accelerations and the resultant of horizontal forces. Attention is focused on the influence of vertical ground motion on seismic-induced displacements of the structure. Experimental investigations performed in order to validate a numerical algorithm are described, and then experimental data are compared with numerical predictions. A good agreement is obtained. Then, the dynamics analysis of the block is presented for harmonic and pseudo-stochastic ground motions in order to illustrate the algorithm proposed. The results of computations show that, for some typical data and ground accelerations corresponding to strong earthquakes, large permanent displacements of the block take place, as observed in real conditions. 相似文献
320.
Vladislav J. Kecojevic Marek J. Mrugala William A. Wilkinson 《Fragblast: International Journal for Blasting and Fragmentation》2003,7(3):167-179
State-of-the-art software and computer technology provides a vehicle for a new approach to designing and verification of blasting patterns and training of professionals in this area of mining. The objective of this paper is to discuss the use of 3-D computer graphics to improve the understanding of the challenges facing drill and blast operations and describe technologies available for drill and blast planning in surface mining. It is postulated that this approach will have a positive impact on future students, researchers, and mine operators by improving their ability to use techniques, skills, and visually rich tools in solving and documenting mining engineering problems. 相似文献