Including the Drag Effects of Canopies: Real Case Large-Eddy Simulation Studies     

Pierre Aumond  Valery Masson  Christine Lac  Benoit Gauvreau  Sylvain Dupont  Michel Berengier 《Boundary-Layer Meteorology》2013,146(1):65-80

We use the mesoscale meteorological model Meso-NH, taking the drag force of trees into account under stable, unstable and neutral conditions in a real case study. Large-eddy simulations (LES) are carried out for real orography, using a regional forcing model and including the energy and water fluxes between the surface (mostly grass with some hedges of trees) and the atmosphere calculated using a state-of-the-art soil-vegetation-atmosphere-transfer model. The formulation of the drag approach consists of adding drag terms to the momentum equation and subgrid turbulent kinetic energy dissipation, as a function of the foliage density. Its implementation in Meso-NH is validated using Advanced Regional Prediction System simulation results and measurements from Shaw and Schumann (Boundary-Layer Meteorol, 61(1):47?C64, 1992). The simulation shows that the Meso-NH model successfully reproduces the flow within and above homogeneous covers. Then, real case studies are used in order to investigate the three different boundary layers in a LES configuration (resolution down to 2 m) over the ??Lannemezan 2005?? experimental campaign. Thus, we show that the model is able to reproduce realistic flows in these particular cases and confirm that the drag force approach is more efficient than the classical roughness approach in describing the flow in the presence of vegetation at these resolutions.  相似文献   

On rubble-mound breakwaters of composite slope     

Ehud Naheer  Valery Buslov 《Coastal Engineering》1983,7(3):253-270

The geometrical properties of the armor layer of rubble mound breakwaters were investigated by observations made on two cases. The first case is a laboratory-scaled model of natural rock, designed with a composite slope. The second is a breakwater in the sea, constructed with a uniform slope of tetrapods. In both cases the cross-section underwent changes, resulting in an apparently stable profile of composite slope. This implied that for stability the optimal armour layer should be of composite slope. The general nature of this profile was implied by the geometrical similarity between the two cases which were basically so different.  相似文献   

From Big to Little Rip in modified F(R,G) gravity     

Andrey N. Makarenko  Valery V. Obukhov  Iliy V. Kirnos 《Astrophysics and Space Science》2013,343(1):481-488

We discuss the cosmological reconstruction in modified Gauss-Bonnet (GB) gravity. It is demonstrated that the modified GB gravity may describe the most interesting features of late-time cosmology. We derive explicit form of effective phantom cosmological models ending by the finite-time future singularity (Big Rip) and without singularities in the future (Little Rip).  相似文献   

New cataclysmic variable 1RXS J073346.0+261933 in Gemini     

D. V. Denisenko  A. J. Drake  S. G. Djorgovski  T. V. Kryachko  A. V. Samokhvalov  A. Yu. Tkachenko 《Astronomy Letters》2011,37(12):858-863

In the course of our search for the optical identifications of ROSAT X-ray sources, we have found a highly variable object with a very unusual behavior on long time scales, rare color indices, and a high X-ray-to-optical flux ratio. We present the archival light curve from the Catalina Sky Survey, optical spectroscopy from RTT150, and time-resolved photometry from the Astrotel-Caucasus telescope. The object appears to be a magnetic cataclysmic variable (a polar) with an orbital period P = 3.20 h.  相似文献   

Measurements of the ionosphere plasma electron density variation by the Kharkov incoherent scatter radar     

Iurii V. Cherniak  Valery N. Lysenko 《Acta Geophysica》2013,61(5):1289-1303

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Middle-Upper Miocene stratigraphy of the Taman Peninsula, Eastern Paratethys     

Eleonora P. Radionova  Larisa A. Golovina  Natalia Yu. Filippova  Valery M. Trubikhin  Sergey V. Popov  Irina A. Goncharova  Yulia V. Vernigorova  Tatiana N. Pinchuk 《Central European Journal of Geosciences》2012,4(1):188-204

The stratigraphy of the Taman Peninsula is defined using the sections at Zelensky Hill ?? Panagia, Popov Kamen, Taman and Zheleznyi Rog. The stratigraphy is constructed from distribution of mollusks, foraminifers, nannofossils, diatoms, and organic-walled phytoplankton, as well as incorporating paleomagnetic data. The occurrence of oceanic diatom species in the Middle-Upper Sarmatian, Maeotian and Lower Pontian makes a direct correlation possible between the sections studied, the Mediterranean basin and oceanic zonation. The new data on planktonic and benthic biotic groups suggests a pulsating connection of the Eastern Paratethys with the open marine basins, especially during transitional intervals within constant environments. Comprehensive studies of the Chokrakian-Kimmerian microbiota provide evidence for several levels of marine microbiotic associations that are related to short-term marine invasions. The biotic and paleomagnetic data of the Taman Peninsula sections give a more comprehensive, but sometimes a controversial picture on the Eastern Paratethys history and the nature of its relationship with the adjacent marine basins.  相似文献   

Flux-Gate Magnetometers Design Peculiarities     

Valery Korepanov  Andriy Marusenkov 《Surveys in Geophysics》2012,33(5):1059-1079

The most widespread instrument used today for the measurement of quasi-stationary and slowly fluctuating vector magnetic fields is a flux-gate magnetometer (FGM). The most important parameter characterizing the magnetometer quality is its magnetic noise—its threshold sensitivity or its own noise level (NL). Based on the results of experimental research, we may state that the FGM NL mainly depends on the quality of the magnetic material used for FGM sensor core. The “solid liquid” model explaining the nature of magnetic noise is proposed and substantiated. It is demonstrated that special attention has to be paid to the annealing of the core. A new effect—termed gamma-magnetic normalization—is discovered and discussed. It is shown that the magnetometer NL depends not only on the core length and volume but also on the excitation mode of the core. Besides, the ways to improve other factors, such as power consumption and thermal drift which must be taken into account in order to create a FGM with the highest possible performance, are discussed. Some examples are given of the parameters of present advanced FGMs for geophysical uses.  相似文献   

Propagating PZ 90 to WGS 84 Transformation Parameters     

Yuri A. Bazlov  Viktor F. Galazin  Boris L. Kaplan  Valery G. Maksimov  Vladimir P. Rogozin 《GPS Solutions》1999,3(1):13-16

The 29^th Research Institute recently published its latest transformation parameters for WGS and PZ 90. Because these tranformation parameter estimates were derived from stations located within Russia, variance-covariance propagation was carried out to study the benefits of a better global distribution of stations. An example that includes two stations in North America is presented. The transformation improves significantly. ? 1999 John Wiley & Sons, Inc.  相似文献   

Spatial dealiasing of 3-D seismic reflection data     

Shuki Ronen  Valery Sorin  Richard Bale 《Geophysical Journal International》1991,105(2):503-511

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The comparable analysis of the Cepheids and non-variable supergiants from the instability strip.I     

Sergei M. Andrievsky  Valery V. Kovtyukh 《Astrophysics and Space Science》1996,245(1):61-80

The elemental abundances, temperatures, gravities and microturbulence velocities were derived for 14 non-variable supergiants from the Cepheids' instability strip and two hotter supergiants. For 8 stars the abundances were determined for the first time. The comparable analysis of the program stars' chemical composition and that of the small-amplitude Cepheids has shown that there is no essential differences in the elemental abundances for two stellar groups. Some discussion of the phenomenon of non-variable supergiants in the instability strip is given.  相似文献