1 Introduction Many of the stratified lakes are characterized by the presence of large populations of cryptomonads in their chemocline zones(Reynolds,1992;Gervais et al,2003;Pedro’s-Alio’et al.,1995).These populations are adapted to low light intensity and high sulfide concentration;they have a mixotrophic ability and form the so-called"deep chlorophyll maxima"(Gervais,1998;Marsha"and Laybourn-Parry,2002).A similar Cryptomonas sp.
This paper focuses on the problem of control law optimization for marine vessels working in a dynamical positioning （DP） regime. The approach proposed here is based on the use of a special unified multipurpose control law structure constructed on the basis of nonlinear asymptotic observers, that allows the decoupling of a synthesis into simpler particular optimization problems. The primary reason for the observers is to restore deficient information concerning the unmeasured velocities of the vessel. Using a number of separate items in addition to the observers, it is possible to achieve desirable dynamical features of the closed loop connection. The most important feature is the so-called dynamical corrector, and this paper is therefore devoted to solving its optimal synthesis in marine vessels controlled by DP systems under the action of sea wave disturbances. The problem involves the need for minimal intensity of the control action determined by high frequency sea wave components. A specialized approach for designing the dynamical corrector is proposed and the applicability and effectiveness of the approach are illustrated using a practical example of underwater DP system synthesis.
At present,mainly GIS software is used for exploration and visualization of spatially distributed data.At the same time an approach based on the combination of advanced web technologies along with the standard rules of information-computational system development is more suitable for performing tasks requiring more sophisticated data analysis.In this report,functional capabilities of the information-computational system created for meteorological and climatic data processing and online visualization are introduced.The system represents a dedicated web-interface,which allows performing of mathematical and statistical operations on the diverse observational and model data and to determine characteristics of global and regional climate changes.Currently such datasets as NCEP/NCAR Reanalysis,ECMWF ERA-40 Reanalysis,etc.are available for processing.In particular,the system allows calculating of temporal average and extremum values,time trends,etc.at arbitrary spatial and temporal ranges for different meteorological parameters.The possibility of online intercomparison of meteorological characteristics calculated for different datasets is also realized in the system.The final version of the system being developed is supposed to find application in meteorological and climatological investigations and should help researchers to save time during performing routine analytical tasks by simplifying handling of huge arrays of spatially distributed meteorological data.
This study provides new insights into the nature of seasonal variations in coordinate time series of GPS sites located near active faults and methods of their modeling. Monthly averaged coordinate time series were analyzed for several pairs of collocated GPS sites situated near the active fault intersection area, in close proximity to the central part of the northern boundary of the Amurian plate and the vicinity of the San Andreas Fault zone. It is concluded that the observed seasonal variations are best described by a breather function which is one of the solutions of the well-known sine-Gordon equation. The obtained results suggest that, in this case, the source of seasonal variations may be caused by the appearance of solitary strain waves in the fault intersection system, which may be qualitatively treated as standing waves of compression-extension of the geological medium. Based on statistical testing, the limits of applicability of the suggested model have been established.
Sergey V. TROFIMENKOVictor G. BYKOVNikolay V. SHESTAKOVNikolay N. GRIBHiroaki TAKAHASHI
Experiments at the GARPUN KrF laser facility and 2D simulations using the NUTCY code were performed to study the irradiation of metal and polymethyl methacrylate(PMMA)targets by 100 nsUVpulses at intensities up to 5×10^(12)Wcm^(−2).In both targets,a deep crater of length 1mm was produced owing to the 2D geometry of the supersonic propagation of the ablation front in condensed matter that was pushed sideways by a conical shock wave.Small-scale filamentation of the laser beam caused by thermal self-focusing of radiation in the crater-confined plasma was evidenced by the presence of a microcrater relief on the bottom of the main crater.In translucent PMMA,with a penetration depth forUVlight of several hundred micrometers,a long narrow channel of length 1mmand diameter 30μmwas observed emerging from the crater vertex.Similar channels with a length-to-diameter aspect ratio of∼1000 were produced by a repeated-pulse KrF laser in PMMA and fused silica glass at an intensity of∼10^(9)Wcm^(−2).This channel formation is attributed to the effects of radiation self-focusing in the plasma and Kerr self-focusing in a partially transparent target material after shallow-angle reflection by the crater wall.Experimental modeling of the initial stage of inertial confinement fusion-scale direct-drive KrF laser interaction with subcritical coronal plasmas from spherical and cone-type targets using craterconfined plasmas seems to be feasible with increased laser intensity above 10^(14) W cm^(−2).
This paper includes a short historical review of Russian and Soviet scientific traverses to study the Antarctic inland. The first traverse left on April 2, 1956. It resulted in the opening of the first Russian inland research station named Pionerskaya and provided the first geophysical and glaciological data on regions inland of the Antarctic coast. By 1965, a number of regional inland scientific traverses had been completed and. the first Atlas of Antarctica was published in 1966. The atlas presented the main achievements of that time. After the discovery of Lake Vostok, Russian scientists commenced remote sensing investigations to study this unique natural phenomenon. The propagation of acoustic and electromagnetic waves in the glacier near Vostok Station were measured to provide important geophysical data. Radio-echo sounding data showed that Lake Vostok is isolated and separated from the rest of the Antarctic subglacial hydrosphere. The total area of the lake is 15 790 km2, excluding 365 km^2 occupied by 11 islands. Reflection seismic soundings of Lake Vostok estimated a total volume of about 6 100 km^3, an average depth of about 400 m, and a maximum depth of 1 200 m. Since 2008, there have been a number of scientific traverses between Mirny and Vostok stations and between Progress and Vostok stations. The data collected during the traverses have provided new insights into sub-ice topography and ice sheet structure, and have led to the discovery of subglacial lakes near Komsomolskaya Station and under Pionerskaya Station.
