Evaluation of the Soviet population census 1970     

Vadim V Pokshishevsky 《Geoforum》1972,3(1):3-5

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Estimating Crustal Heterogeneity from Double-difference Tomography     

Jean -Luc Got  Vadim Monteiller  Jean Virieux  Paul Okubo 《Pure and Applied Geophysics》2006,163(2-3):405-430

Seismic velocity parameters in limited, but heterogeneous volumes can be inferred using a double-difference tomographic algorithm, but to obtain meaningful results accuracy must be maintained at every step of the computation. MONTEILLER et al. (2005) have devised a double-difference tomographic algorithm that takes full advantage of the accuracy of cross-spectral time-delays of large correlated event sets. This algorithm performs an accurate computation of theoretical travel-time delays in heterogeneous media and applies a suitable inversion scheme based on optimization theory. When applied to Kilauea Volcano, in Hawaii, the double-difference tomography approach shows significant and coherent changes to the velocity model in the well-resolved volumes beneath the Kilauea caldera and the upper east rift. In this paper, we first compare the results obtained using MONTEILLER et al.'s algorithm with those obtained using the classic travel-time tomographic approach. Then, we evaluated the effect of using data series of different accuracies, such as handpicked arrival-time differences (``picking differences'), on the results produced by double-difference tomographic algorithms. We show that picking differences have a non-Gaussian probability density function (pdf). Using a hyperbolic secant pdf instead of a Gaussian pdf allows improvement of the double-difference tomographic result when using picking difference data. We completed our study by investigating the use of spatially discontinuous time-delay data.  相似文献   

Plio-Pleistocene geological record and small mammal faunas, eastern shore of the Azov Sea, Southern European Russia   总被引：1，自引：0，他引：1  

Alexey S. Tesakov  Andrey E. Dodonov  Vadim V. Titov  Valery M. Trubikhin 《Quaternary International》2007,160(1):57

The shoreline of the Taganrog Gulf of the Azov Sea at the mouth of Don River provides a series of extended Upper Pliocene and Quaternary sections that have been actively studied in the last century. This extraglacial region had a complex sedimentary history combining subaerial aggradation with marine, fluvial, and deltaic sedimentation. The well-exposed stratigraphical sequence and abundant palaeontological record continuously attract geologists and highlight the region as one of international importance for the addressing of numerous problems of Late Pliocene and Quaternary stratigraphy and palaeogeography. Fossil mammalian faunas of the region include important Eurasian biostratigraphical markers such as Stenocranius ex gr. hintoni-gregaloides, Lagurini spp., and Mimomys savini. For many years, fossil remains of mammals provide decisive clues to the geological history of the region. Recent geological studies of reference sections have provided data on small mammals, palaeomagnetism and palaeogeographical reconstructions in the northeastern part of the Azovian Region. Mammalian assemblages indicate the presence of the Late Pliocene, late Early Pleistocene, Middle Pleistocene and Late Pleistocene levels and, in addition, provide a clear biostratigraphical context for the Early Middle Pleistocene transition.  相似文献   

The Contribution of Magnetic Flux Tubes to Brightness Fluctuations on the Extreme Limb of the Sun     

Karpinsky  Vadim N.  Okunev  Oleg V. 《Solar physics》1998,183(2):277-282

Magnetic flux tubes are considered to be a possible source of observed brightness variations on the extreme limb of the Sun. A computer code to simulate the brightness fluctuations is developed. It follows from numerical modeling that a filling factor of f=4% is required to explain the observed fine structure. Such a value is typical for the boundaries of supergranules. Tubes produce a local maximum of intensity just inside the limb.  相似文献   

Trace-element study and uranium-lead dating of perovskite from the Afrikanda plutonic complex, Kola Peninsula (Russia) using LA-ICP-MS     

Ekaterina P. Reguir  Alfredo Camacho  Panseok Yang  Anton R. Chakhmouradian  Vadim S. Kamenetsky  Norman M. Halden 《Mineralogy and Petrology》2010,100(3-4):95-103

The U-Pb geochronology of perovskite is a powerful tool in constraining the emplacement age of silica-undersaturated rocks. The trace-element and U-Pb isotopic compositions of perovskite from clinopyroxenite and silicocarbonatite from the Afrikanda plutonic complex (Kola, Russia) were determined by laser-ablation inductively-coupled mass-spectrometry (LA-ICP-MS). In addition, the Sr isotopic composition of perovskite was measured by isotope-dilution mass-spectrometry to better constrain the relations between its host rocks. Perovskite from the two rock types shows a different degree of enrichment in Na, Mg, Mn, Pb, Fe, Al, V, rare-earth elements, Zr, Hf, Th, U and Ta. The perovskite ⁸⁷Sr/⁸⁶Sr values are within analytical uncertainty of one another and fall within the range of mantle values. The ²⁰⁶Pb/²³⁸U ages (corrected for common lead using ²⁰⁷Pb-method) of perovskite from silicocarbonatite statistically yield a single population with a weighted mean of 371?±?8 Ma (2σ; MSWD?=?0.071). This age is indistinguishable, within uncertainty, to the clinopyroxenite weighted mean ²⁰⁶Pb/²³⁸U age of 374?±?10 Ma (2σ; MSWD?=?0.18). Our data are in good agreement with the previous geochronological study of the Afrikanda complex. The observed variations in trace-element composition of perovskite from silicocarbonatite and clinopyroxenite indicate that these rocks are not related by crystal fractionation. The Sr isotopic ratios and the fact that the two rocks are coeval suggest that they were either produced from a single parental melt by liquid immiscibility, or from two separate magmas derived at different degrees of partial melting from an isotopically equilibrated, but modally complex mantle source.  相似文献   

Geoarchaeological and Bioarchaeological Studies at Mira,an Early Upper Paleolithic Site in the Lower Dnepr Valley,Ukraine     

John F. Hoffecker  Vance T. Holliday  Vadim N. Stepanchuk  Alexis Brugre  Steven L. Forman  Paul Goldberg  Oleg Tubolzev  Igor Pisarev 《Geoarchaeology》2014,29(1):61-77

New geoarchaeological and bioarcheological research was undertaken at the open‐air site of Mira, which is buried in deposits of the Second Terrace of the Dnepr River, roughly 15 km downstream from the city of Zaporozhye in Ukraine. Previous excavation of the site revealed two occupation layers dating to ∼32,000 cal BP. The lower layer (II/2) yielded bladelets similar to those of the early Gravettian, while the upper layer (I) contained traces of an artificial shelter and hundreds of bones and teeth of horse (Equus latipes). Mira represents the only firmly dated early Upper Paleolithic (EUP) site in the Dnepr Basin, and occupies a unique topographic setting for the EUP near the center of the broad floodplain of the Dnepr River. The site was visited during a period of floodplain stability, characterized by overbank deposition and weak soil formation under cool climate conditions. Mira was used as a long‐term camp, but also was the locus of large‐mammal carcass processing associated with a nearby kill of a group of horses (Layer I).  相似文献   

The influence of freeze-thaw cycles on the granulometric composition of Moscow morainic clay   总被引：2，自引：0，他引：2  

Ze Zhang  Vadim V. Pendin  WenJie Feng  ZhongQiong Zhang 《寒旱区科学》2015,7(3):199-205

The freeze-thaw cycling process considerably changes the composition,structure,and properties of soils.Since the grain size is the most important factor in determining soil characteristics,our current research primarily aims to investigate dynamic changes of the soil fraction when exposed to freeze-thaw conditions.We observed two series of Moscow morainic clayey specimens(g QmII):(I) the original series,and(II) the remolded series.We subjected each series of soil specimens to different frequencies of freeze-thaw cycles(3,6,20,and 40 cycles),and we used granulometric tests to analyze both series before and after exposure to freeze-thaw conditions.As a result of our experiments,the granulometric compositions tended to be distributed evenly after 40 freeze-thaw processes(i.e.,content of fraction for 0.1–0.05 mm was increased after 40 freeze-thaw cycles) because the division of coarse grains and the aggregation of fine grains were synchronized during the freeze-thaw process.The soil grains in both series changed bi-directionally.In the original series,changes of the sand grains were conjugated with the clay grains,and in the remolded series,changes of the sand grains were conjugated with the silt grains,because potential energy difference caused the division and aggregation processes to relate to the counteraction process.The even distribution of soil grain size indicated the state of equilibrium or balance.The granulometric compositions were altered the most during the sixth freeze-thaw cycle,because the coefficient of the intensity variation of the grain fineness(Kvar) had its maximum value at that time.  相似文献   

Robotic optical telescopes global network MASTER II. Equipment, structure, algorithms     

Victor G. Kornilov  Vladimir M. Lipunov  Evgeny S. Gorbovskoy  Aleksander A. Belinski  Dmitry A. Kuvshinov  Natalia V. Tyurina  Nikolai I. Shatsky  Anatoly V. Sankovich  Aleksander V. Krylov  Pavel V. Balanutsa  Vadim V. Chazov  Artem S. Kuznetsov  Dmitry S. Zimnuhov  Victor A. Senik  Andrey G. Tlatov  Aleksander V. Parkhomenko  Denis V. Dormidontov  Vadim V. Krushinsky  Ivan S. Zalozhnyh  Aleksander A. Popov  Sergey A. Yazev  Nikolai M. Budnev  Kirill I. Ivanov  Evgeny N. Konstantinov  Oleg A. Gress  Oleg V. Chvalaev  Vladimir V. Yurkov  Yury P. Sergienko  Irina P. Kudelina 《Experimental Astronomy》2012,33(1):173-196

Presented paper describes the basic principles and features of the implementation of a robotic network of optical telescopes MASTER, designed to study the prompt (simultaneous with gamma radiation) optical emission of gamma-ray bursts and to perform the sky survey to detect unknown objects and transient phenomena. With joint efforts of Sternberg astronomical institute, High altitude astronomical station of the Pulkovo observatory, Ural state university, Irkutsk state university, Blagoveshchensk pedagogical university, the robotic telescopes MASTER?II near Kislovodsk, Yekaterinburg, Irkutsk and Blagoveshchensk were installed and tested. The network spread over the longitudes is greater than 6?h. A further expansion of the network is considered.  相似文献   

CAN WE OBSERVE THE TEMPERATURE INHOMOGENEITIES AND MAGNETIC FLUX TUBES AS THE FINE STRUCTURE ON THE EXTREME LIMB OF THE SUN?     

Karpinsky  Vadim N.  Okunev  Oleg V. 《Solar physics》1997,173(2):233-242

Fine structure of brightness inhomogeneities with I r.m.s. = 2.9% was discovered on the extreme limb of the Sun on the best quality white-light photographs obtained at the Soviet Stratospheric Solar Observatory. The concept is that temperature inhomogeneities are responsible for the limb structure. The real value T r.m.s. = 109K is required to explain our observations. Another possible explanation is that small-scale magnetic flux tubes with the realistic filling factor f* = 1% are the source of the limb brightness fluctuations.  相似文献   

Portlandia-dominated Communities in the Arctic: Taxonomic Composition and Structure along the Geographical Gradient     

Mokievsky  V. O.  Udalov  A. A.  Chava  A. I.  Simakova  U. V.  Kokarev  V. N.  Neretina  T. V. 《Doklady Earth Sciences》2020,493(2):645-648

Doklady Earth Sciences - The species composition and structure of bottom communities with a predominance of bivalve mollusks of the Portlandia genus, which are widespread on the shelf of the...  相似文献