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排序方式: 共有88条查询结果,搜索用时 15 毫秒
1.
多年冻土地区建筑物地基的热稳定性技术 总被引:1,自引:0,他引:1
Thermal stabilization of soils (including freezing of thawed soils and cooling of permafrost) is known to be the effective method providing stable support for buildings and structures in cold regions.Seasonal thermo-stabilizers (STS) are mainly used in construction. The predicted climate warming because of natural and man-caused factors determines wide application of STS in permafrost regions. A STS transfers heat from its underground part (evaporator) to the aerial part (condenser) owing to natural temperature difference between them during a cold season. We have been working out and manufacturing different types of two-phase, vapor-liquid STS. Aluminum alloys are used in our STS to prevent corrosion and to increase their efficiency. They are successfully used in the northern regions of Western Siberia, in particular, at the railway Obskaya Bovanenkovo. The paper presents some technical parameters of new STS, the results of their experimental study and computer simulation, as well as experience features. 相似文献
2.
Larisa A. Savelieva Andrei A. Andreev Raphael Gromig Dmitry A. Subetto Grigory B. Fedorov Volker Wennrich Bernd Wagner Martin Melles 《Boreas: An International Journal of Quaternary Research》2019,48(2):349-360
The new pollen record from the upper 12.75 m of a sediment core obtained in Lake Ladoga documents regional vegetation and climate changes in northwestern Russia over the last 13.9 cal. ka. The Lateglacial chronostratigraphy is based on varve chronology, while the Holocene stratigraphy is based on AMS 14C and OSL dates, supported by comparison with regional pollen records. During the Lateglacial (c. 13.9–11.2 cal. ka BP), the Lake Ladoga region experienced several climatic fluctuations as reflected in vegetation changes. Shrub and grass communities dominated between c. 13.9 and 13.2 cal. ka BP. The increase in Picea pollen at c. 13.2 cal. ka BP probably reflects the appearance of spruce in the southern Ladoga region at the beginning of the Allerød interstadial. After c. 12.6 cal. ka BP, the Younger Dryas cooling caused a significant decrease in spruce and increase in Artemisia with other herbs, indicative of tundra‐ and steppe‐like vegetation. A sharp transition from tundra‐steppe habitats to sparse birch forests characterizes the onset of Holocene warming c. 11.2 cal. ka BP. Pine forests dominated in the region from c. 9.0 to 8.1 cal. ka BP. The most favourable climatic conditions for deciduous broad‐leaved taxa existed between c. 8.1 and 5.5 cal. ka BP. Alder experiences an abrupt increase in the local vegetation c. 7.8 cal. ka BP. The decrease in tree pollen taxa (especially Picea) and the increase in herbs (mainly Poaceae) probably reflect human activity during the last 2.2 cal. ka. Pine forests have dominated the region since that time. Secale and other Cerealia pollen as well as ruderal herbs are permanently recorded since c. 0.8 cal. ka BP. 相似文献
3.
4.
Fishchenko V. K. Dolgikh G. I. Zimin P. S. Subote A. E. 《Doklady Earth Sciences》2018,482(1):1244-1247
The design features of an oceanological video-monitoring system created for operational research of coastal infrasonic wave processes are described. The results obtained confirm great opportunities for its use in fundamental and applied works in various seasons. The processing of the obtained experimental data has revealed the dynamics of the wave processes starting from wind waves to diurnal tides.
相似文献5.
The determination of uranium series disequilibria in fluvial environments is proposed as a method of calculating catchment mass balances. The technique is based on two main principles. Firstly, 234U is more mobile than 238U, especially during the early stages of weathering. Secondly, uranium is far more mobile than either thorium or protactinium. Consequently, teaching during weathering results in the loss of the uranium found in the fresh rock, leaving the two immobile daughters behind. The ratio of uranium carried by sediment to that dissolved, US/UW can, therefore, be determined from river water and sediment isotopic activity ratios. Fluxes of uranium can then be calculated from average concentrations in the water and the associated sediment, from which a sediment yield can be inferred. The Witham catchment in Lincolnshire has been used to test the proposed method. A US/UW ratio of between 5 and 7 is determined and a sediment yield of 2.51 ± 2.12 tonnes yr?1 km?2 is proposed. Although some problems concerning environmental chemistry have arisen, the validity of the approach is confirmed by the close correspondence between the results obtained and those inferred by earlier workers using more conventional methods. 相似文献
6.
Land use changes in the environs of Moscow 总被引:1,自引:0,他引:1
This paper focuses on several aspects of land use change in Russia during the 1990s with a particular focus on the environs of Moscow. These aspects include modes of farming, recreation, ownership of land, and concentric zones of outwardly declining land use intensity that resemble Von Thunen's economic landscape. These zones are given special attention. In contrast to other land use aspects, the analysis of which indeed reveals a fair amount of change bringing the environs of Russian cities one step closer to their Western counterparts, concentric agricultural land use patterns with outwardly declining productivity suggest continuity rather than change. 相似文献
7.
Brenda S. Pierce Artur Martirosyan Gourgen Malkhasian Samvel Harutunian Grigory Harutunian 《International Journal of Coal Geology》2001,45(4):307
The Antaramut–Kurtan–Dzoragukh (AKD) coal deposit is a previously unrecognized coal field in north-central Armenia. Coal has been known to exist in the general vicinity since the turn of the century, but coal was thought to be restricted to a small (1 km2) area only near the village of Antaramut. However, through detailed field work and exploratory drilling, this coal deposit has been expanded to at least 20 km2, and thus renamed the Antaramut–Kurtan–Dzoragukh coal field, for the three villages that the coal field encompasses. The entire coal-bearing horizon, a series of tuffaceous sandstones, siltstones, and claystones, is approximately 50 m thick. The AKD coal field contains two coal beds, each greater than 1 m thick, and numerous small rider beds, with a total resource of approximately 31,000,000 metric tonnes. The coals are late Eocene in age, high volatile bituminous in rank, relatively high in ash yield (approximately 40%, as-determined basis) and moderate in sulfur content (approximately 3%, as-determined basis). The two coal beds (No. 1 and No. 2), on a moist, mineral-matter-free basis, have high calorific values of 32.6 MJ/kg (7796 cal/g) and 36.0 MJ/kg (8599 cal/g), respectively. Coal is one of the few indigenous fossil fuel resources occurring in Armenia and thus, the AKD coal field could potentially provide fuel for heating and possibly energy generation in the Armenian energy budget. 相似文献
8.
D.O. Olago F.A. Street-Perrott R.A. Perrott M. Ivanovich D.D. Harkness 《Journal of African Earth Sciences》2000,30(4):1113
In this paper, a sequence of five Late Quaternary tephras occurring as discrete, well-preserved horizons in lake sediments on the northeastern flank of Mount Kenya are characterised and their ages determined by a combination of high-resolution indirect radiocarbon dating and direct
dating. The grain size characteristics suggest that the tephras are of fairly local origin. These Na---K-rich alkali pyroclasts with a trachytic chemical composition have a highly correlated chemistry and mineralogy, suggesting that they were probably derived from the same genetic series and possibly erupted from a single source vent. Morphological differences are attributed to the peculiar characteristics of each eruption episode. The magma source was probably a small, highly differentiated magma chamber following the olivine basalt-trachyandesite-trachyte-phonolite series, which broadly reflects the Quaternary rock suite of Mount Kenya. 相似文献
9.
Grigory I. Dolgikh Mstislav N. Dubrov Stanislav G. Dolgikh Sergei N. Kovalev Vladimir V. Ovcharenko Egor A. Savvin Vladimir A. Chupin Vyacheslav A. Shvets Sergei V. Yakovenko 《Acta Geophysica》2006,54(2):187-197
The paper considers possibilities of applying laser strainmeters for the study of earthquake physics. One of laser strainmeters
is described. A high efficiency of using the laser strainmeters for the study of earthquakes and their precursors is shown.
In records of the spaced laser strainmeters, anomalous deformations propagating from the east to the west with the speed comparable
with that of migration of earthquakes were found. 相似文献
10.
A model of forced magnetic reconnection in a force-free magnetic field is considered, which allows calculation of the magnetic
energy release during the current sheet reconnection. The dependence of this energy on characteristics of the magnetic configuration
has been studied, and it was found that the released energy becomes very large when the field is near the marginal tearing
stability. A persistent plasma heating provided by ongoing external driving and internal reconnection is also derived. It
shows a typical relaxation-type dependence on the driving frequency, with dissipation becoming most efficient when the time-scales
of the driving and reconnection are comparable. Possible implications of the obtained results for the problem of solar coronal
heating are discussed.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献