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991.
I. G. Granberg V. F. Kramar R. D. Kuznetsov O. G. Chkhetiani M. A. Kallistratova S. N. Kulichkov M. S. Artamonova D. D. Kuznetsov V. G. Perepelkin V. V. Perepelkin F. A. Pogarskii 《Izvestiya Atmospheric and Oceanic Physics》2009,45(5):541-548
The studies conducted in 1991–2004 by scientists of the A.M. Obukhov Institute of Atmospheric Physics, Russian Academy of Sciences, and the Karpov Institute of Physical Chemistry yielded data on the structures of the surface air layer (to a height of 20 m) and both subinversion and inversion layers (to heights of from 800 m to 1 km), where arid aerosol is transported. One of the main objectives of the 2007 experiment was to record the space-vortex structures within a layer of 30–700 m that directly provide the removal and long-range transport of fine-dispersed (<5 µm) desert aerosol. This paper describes the organization of the Khar-Gzyr 2007 experiment (Black Lands, 2007) to study the convective removal of arid aerosol from desertificated lands, and it presents some data obtained from the remote sensing of the atmospheric boundary layer with a sodar network in the course of this experiment. The sodar network, which was developed to study a spatial structure of coherent vortices, included three identical minisodars (with carrier frequencies of 3.8 kHz) located at the apices of a triangle, each side of which was about 3.5 km, and a sodar (with a carrier frequency of 1.7 kHz). The vertical profiles of the three wind-velocity components and the characteristics of air temperature fluctuations were determined. The procedure of identifying coherent vortex structures is described. The variations in the vertical and horizontal wind-velocity components and the scales characteristic of such structures are estimated. 相似文献
992.
М.Lebedeva 《山地科学学报》2009,6(2):132-138
Micromorphology of solonetz species with special attention to natric horizon was studied in microcatenas at the Dzhanybek Research Station (northwestern Caspian Lowland). The solonetzic (natric) horizon is easily identified, and it occurs at varying depths, which are the criteria for subdividing solonetzes into 4 species, namely, crusty, shallow, medium and deep. In this sequence, the depth of humus-accumulative horizons increases, and the upper boundary of salinity manifestations goes down. The following micromorphological features are assumed as typical for natric horizons: angular blocky microstructures with partially accommodated aggregates having sharp boundaries and narrow plane-like packing voids; b-fabric speckled in the aggregates' centers and monostriated at their peripheries merging into stress coatings; very few interpedal voids; organo-clay coatings; humus- enriched infillings; no calcite and gypsum pedofeatures. A complete set of "natric" features was found only in the crusty solonetz; the shallow solonetz lacks only illuviation coatings, while the medium and deep species have several modifications of fabric elements: blocky aggregates have a rounded shape and are penetrated by biogenic channels favoring their further biogenic reworking; plant residues became more abundant and diverse, and blackened tissues occur; illuviation clay coatings evolved into papules; stress coatings gave birth to striated bfabrics, thus maintaining a high plasma orientation. The thin sections of natric horizons made 50 and 20 years ago were examined to study the influence of environmental changes (increase in precipitation and rise of ground water table) on micropedofeatures. The following processes took place: (i) in the topsoil: humus accumulation and biogenic structurization; (ii) in the natric horizon - re-arrangement of clay coatings into micromass b-fabrics; and (iii) in the lower part of the natric horizon - development of pseudosand fabric, calcite and gypsum formation. The trends revealed are in good agreement with the environmental events. 相似文献
993.
994.
Seiche oscillations of the Azov Sea level are studied on the basis of the developed two-dimensional numerical hydrodynamic
model grounded on the shallow water theory and recent data on the morphometric characteristics of the Sea of Azov. Frequency
and spatial characteristics of the first five modes corresponding to seiche oscillations of the Azov Sea level are computed.
It is shown that the frequency and spatial characteristics of the first five modes obtained for the Sea of Azov level changes
correspond to seiche oscillations. The calculated parameters are compared with the field observations, which show their realistic
character. 相似文献
995.
The proposed concept of the “marine coastal zone” (MCZ) is substantiated with considering the role of the neotectonics in
the formation and evolution of the corresponding morphologic system using the Antarctic Peninsula as an example. For this
purpose, the results of the immediate geologic-geomorphologic observations are correlated with an original schematic neotectonic
map compiled for the region in question. It is shown that neotectonic movements are responsible for the block structure of
the coastal zone representing its most stable element, which is complicated by subsequent regional exogenic coast-forming
processes with the glacial one being dominant. Other aspects of the marine coastal zone influenced by neotectonics are also
considered. A new (near-polar) type of the marine coastal zone is defined. 相似文献
996.
997.
In recent years, considerable amount of effort has been made to design earthquake resistant offshore structures in seismic active areas. In order to achieve this objective, all components of a typical structure should function properly to dissipate seismically-induced energy within the members. Among components of an offshore installation, braces are of significant importance as they contribute substantially to total energy dissipation of the structure. Buckling in compression and yielding in tension assist the process of energy absorption. Nevertheless, the functionality of braces is dependent upon their joints where joint-cans are included to avoid any brittle fracture and unpredicted failure mechanisms.In this paper, special attention is being paid to energy dissipation of jacket type offshore platforms with two different pile–leg interactions. A case study representing an offshore platform is studied both analytically and experimentally. Analytical models are validated step by step based on available experimental tests and observations on individual members. Several parameters such as cyclic behavior, maximum bearing load and most importantly energy dissipation of two different 2D frames are investigated. Results provide promising insights into design and fabrication of fixed platforms with different pile–leg interactions. 相似文献
998.
Marianne Alunno-Bruscia Henk W. van der Veer Sebastiaan A.L.M. Kooijman 《Journal of Sea Research》2009,62(2-3):43
The European Research Project AquaDEB (2007–2011, http://www.ifremer.fr/aquadeb/) is joining skills and expertise of some French and Dutch research institutes and universities to analyse the physiological flexibility of aquatic organisms and to link it to ecological and evolutionary processes within a common theoretical framework for quantitative bioenergetics [Kooijman, S.A.L.M., 2000. Dynamic energy and mass budgets in biological systems. Cambridge University Press, Cambridge]. The main scientific objectives in AquaDEB are i) to study and compare the sensitivity of aquatic species (mainly molluscs and fish) to environmental variability of natural or human origin, and ii) to evaluate the related consequences at different biological levels (individual, population, ecosystem) and temporal scales (life cycle, population dynamics, evolution). At mid-term life, the AquaDEB collaboration has already yielded interesting results by quantifying bio-energetic processes of various aquatic species (e.g. molluscs, fish, crustaceans, algae) with a single mathematical framework. It has also allowed to federate scientists with different backgrounds, e.g. mathematics, microbiology, ecology, chemistry, and working in different fields, e.g. aquaculture, fisheries, ecology, agronomy, ecotoxicology, climate change. For the two coming years, the focus of the AquaDEB collaboration will be in priority: (i) to compare energetic and physiological strategies among species through the DEB parameter values and to identify the factors responsible for any differences in bioenergetics and physiology; and to compare dynamic (DEB) versus static (SEB) energy models to study the physiological performance of aquatic species; (ii) to consider different scenarios of environmental disruption (excess of nutrients, diffuse or massive pollution, exploitation by man, climate change) to forecast effects on growth, reproduction and survival of key species; (iii) to scale up the models for a few species from the individual level up to the level of evolutionary processes. 相似文献
999.
1000.
Nidhi Nagabhatla R. Wickramasuriya S. N. Prasad 《Journal of the Indian Society of Remote Sensing》2009,37(3):443-455
The present study investigates the potential of readily available and easily accessible global data sets to understand regional/local
level interactions in wetland systems. The biogeographical zones of India were used a base-frame to select three sites. The
study well fits the interests of National Wetland Committee of India to investigate and document fundamental information on
wetland extent/distribution. The national partnership with SACON represents this interest. SACON commenced the inland wetland
inventory module at national scale using geospatial data, although the provincial scale analysis is underway. In addition,
the global irrigated area mapping (GIAM-IWMI) project generated multi-scalar spatial outputs for irrigated/rain-fed areas.
With the existing information base, a multi-level geospatial analysis using Arc GIS algorithmic modelling was used to derive
comprehensive appraisal of wetland systems complementing the data from GIAM and SACON. It was observed that the overlap between
the two layers was 58 percent for Gujarat and 10 percent in Tamil Nadu. In Krishna basin the wetland’s cover 1.04 million
hectare excluding the rice agro-ecosystem. The difference in the biogeography of the case sites governs the gradient of information
derived from both data layers. Additionally, the global lakes and wetlands database (GLWD) database added thematic information
on coastal wetlands. In summary we describe the cross-scaling the global data layers to compliment the regional/national level
monitoring assignments. 相似文献