Farm size comparison with analytical model of linear generator wave energy converters     

Karin Thorburn  Mats Leijon 《Ocean Engineering》2007,34(5-6):908-916

Ocean wave energy is an emerging kind of renewable energy, and several energy conversion methods are available today. One solution is to connect a buoy to a linear generator. Such units are quite small (10–100 kW), and farm solutions are suggested to increase power production. This paper shows the results from small farm simulations where the translator motion is varied for the generators in the farm.Simulations with five and 10 units show that power fluctuations decrease with an increasing number of generators.  相似文献   

Book review of The magnetic universe,geophysical and astrophysical dynamo theory,by G. Rüdiger and R. Hollerbach,Wiley-VCH,Weinheim, 2004, XI+332 pp., £90.00, $161.00, €135.00, hardback (ISBN: 3-527-40409-0).     

Nigel Weiss 《地球物理与天体物理流体动力学》2013,107(4):347-348

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A review of: “Finite-difference techniques for vectorized fluid dynamics calculations”     

N. O. Weiss 《地球物理与天体物理流体动力学》2013,107(4):344-345

Abstract

Edited by D. L. Book. Springer-Verlag, New York, 1981. 226 pp., DM 72,—, $33.60. (ISBN 0 387 104828)  相似文献   

Changing seas in the Early–Middle Miocene of Central Europe: a Mediterranean approach to Paratethyan stratigraphy          下载免费PDF全文

Karin Sant  Dan V. Palcu  Oleg Mandic  Wout Krijgsman 《地学学报》2017,29(5):273-281

The Miocene palaeogeographic evolution of the Paratethys Sea is still poorly constrained. Here, we use modern Mediterranean biochronology to provide an up‐to‐date overview of changing seas in Central Europe. Instead of a Paratethys that waxed and waned with fluctuating global sea levels, we show that the development of different seas was mainly controlled by tectonic phases. The Early Miocene “Ottnangian Sea” (~18 Ma) was connected to the Mediterranean via the Rhône valley, while the “Karpatian Sea” (~16.5 Ma) was initiated by a tectonically induced marine transgression through the Trans‐Tethyan gateway. In most Central European basins, the establishment of the “Badenian Sea” (<15.2 Ma), triggered by subduction‐related processes in the Pannonian and Carpathian domain, is significantly younger (by ~1 Myr) than usually estimated. The updated palaeogeographic reconstructions provide a better understanding of the concepts of basin dynamics, land–sea distribution and palaeoenvironmental change in the Miocene of Central Europe.  相似文献   

Spectral models for solar-scaled and α-enhanced stellar populations     

P. Coelho  G. Bruzual  S. Charlot  A. Weiss  B. Barbuy  J. W. Ferguson 《Monthly notices of the Royal Astronomical Society》2007,382(2):498-514

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Future changes in vegetation and ecosystem function of the Barents Region   总被引：1，自引：0，他引：1  

Annett Wolf  Terry V. Callaghan  Karin Larson 《Climatic change》2008,87(1-2):51-73

The dynamic vegetation model (LPJ-GUESS) is used to project transient impacts of changes in climate on vegetation of the Barents Region. We incorporate additional plant functional types, i.e. shrubs and defined different types of open ground vegetation, to improve the representation of arctic vegetation in the global model. We use future climate projections as well as control climate data for 1981–2000 from a regional climate model (REMO) that assumes a development of atmospheric CO₂-concentration according to the B2-SRES scenario [IPCC, Climate Change 2001: The scientific basis. Contribution working group I to the Third assessment report of the IPCC. Cambridge University Press, Cambridge (2001)]. The model showed a generally good fit with observed data, both qualitatively when model outputs were compared to vegetation maps and quantitatively when compared with observations of biomass, NPP and LAI. The main discrepancy between the model output and observed vegetation is the overestimation of forest abundance for the northern parts of the Kola Peninsula that cannot be explained by climatic factors alone. Over the next hundred years, the model predicted an increase in boreal needle leaved evergreen forest, as extensions northwards and upwards in mountain areas, and as an increase in biomass, NPP and LAI. The model also projected that shade-intolerant broadleaved summergreen trees will be found further north and higher up in the mountain areas. Surprisingly, shrublands will decrease in extent as they are replaced by forest at their southern margins and restricted to areas high up in the mountains and to areas in northern Russia. Open ground vegetation will largely disappear in the Scandinavian mountains. Also counter-intuitively, tundra will increase in abundance due to the occupation of previously unvegetated areas in the northern part of the Barents Region. Spring greening will occur earlier and LAI will increase. Consequently, albedo will decrease both in summer and winter time, particularly in the Scandinavian mountains (by up to 18%). Although this positive feedback to climate could be offset to some extent by increased CO₂ drawdown from vegetation, increasing soil respiration results in NEE close to zero, so we cannot conclude to what extent or whether the Barents Region will become a source or a sink of CO₂.  相似文献   

Typecasting prospective Au-bearing sedimentary lithologies using sedimentary geochemistry and Nd isotopes in poorly exposed Proterozoic basins of the Tanami region, Northern Australia     

Alexis Lambeck  David Huston  Karin Barovich 《Mineralium Deposita》2010,45(5):497-515

The development of a regional stratigraphy in Palaeoproterozoic basins within the Tanami region, Northern Australia has been hindered by the difficulty of discriminating sedimentary units and facies across this isolated and poorly exposed basin. A regional stratigraphy is important as it provides constraints on sedimentary basin evolution and assists in gold exploration. Gold is known to be more concentrated in certain rock formations. Based on Nd isotopes and whole rock geochemistry, five main sedimentary events have been identified in the Tanami region. Some sedimentary units were derived from homogeneous local sources, whereas others contain evidence of a well-mixed fine-grained remote provenance. Within the basins, major gold-bearing lithologies are characterised by mafic source indicators: (1) high Cr/Th ratios; (2) low Th/Sc ratios; (3) low (La/Yb)_PAAS ratios relative to Post-Archaean Average Shale (Taylor and McLennan 1985); (4) Eu anomalies equal to ∼1; and (5) distinctive ranges in initial ε _Nd values. Potential future exploration target areas have been identified in the Tanami region at the Cashel and Sunline prospects using these geochemical parameters.  相似文献   

Pulsation period changes as a tool to identify pre-zero age horizontal branch stars     

V. Silva Aguirre  M. Catelan  A. Weiss  A. A. R. Valcarce 《Astrophysics and Space Science》2010,328(1-2):123-127

One of the most dramatic events in the life of a low-mass star is the He flash, which takes place at the tip of the red giant branch (RGB) and is followed by a series of secondary flashes before the star settles into the zero-age horizontal branch (ZAHB). Yet, no stars have been positively identified in this key evolutionary phase, mainly for two reasons: first, this pre-ZAHB phase is very short compared to other major evolutionary phases in the life of a star; and second, these pre-ZAHB stars are expected to overlap the loci occupied by asymptotic giant branch (AGB), HB, and RGB stars observed in the color-magnitude diagram (CMD). We investigate the possibility of detecting these stars through stellar pulsations, since some of them are expected to rapidly cross the Cepheid/RR Lyrae instability strip in their route from the RGB tip to the ZAHB, thus becoming pulsating stars along the way. As a consequence of their very high evolutionary speed, some of these stars may present anomalously large period change rates. We constructed an extensive grid of stellar models and produced pre-ZAHB Monte Carlo simulations appropriate for the case of the Galactic globular cluster M3 (NGC 5272), where a number of RR Lyrae stars with high period change rates are found. Our results suggest that some—but certainly not all—of the RR Lyrae stars in M3 with large period change rates are in fact pre-ZAHB pulsators.  相似文献   

Characteristics of oceanic impact‐induced large water waves—Re‐evaluation of the tsunami hazard     

Kai Wünnemann  Robert Weiss  Kay Hofmann 《Meteoritics & planetary science》2007,42(11):1893-1903

Abstract— The potential hazard of a meteorite impact in the ocean is controversial with respect to the destructive power of generated large ocean waves (tsunamis). We used numerical modeling of hypervelocity impact to investigate the generation mechanism and the characteristics of the resulting waves up to a distance of 100–150 projectile radii. The wave signal is primarily controlled by the ratio between projectile diameter and water depth, and can be roughly classified into deep‐water and shallow‐water impacts. In the latter, the collapse of the crater rim results in a wave signal similar to solitary waves, which propagate and decay in agreement with shallow‐water wave theory. The much more likely scenario for an asteroid impact on Earth is a relatively small body (much smaller than the water depth) striking the deep sea. In this case, the collapse of the transient crater results in a significantly different and much more complex wave signal that is characterized by strong nonlinear behavior. We found that such waves decay much more rapidly than previously assumed and cannot be treated as long waves. For this reason, the shallow‐water theory is not applicable for the computation of wave propagation, and more complex models (full solution of the Boussinesq equations) are required.  相似文献   

Intercomparison of Himawari-8 AHI-FSA with MODIS and VIIRS active fire products   总被引：1，自引：0，他引：1  

Chathura Wickramasinghe  Luke Wallace  Karin Reinke  Simon Jones 《International Journal of Digital Earth》2020,13(4):457-473

ABSTRACT

The AHI-FSA (Advanced Himawari Imager - Fire Surveillance Algorithm) is a recently developed algorithm designed to support wildfire surveillance and mapping using the geostationary Himawari-8 satellite. At present, the AHI-FSA algorithm has only been tested on a number of case study fires in Western Australia. Initial results demonstrate potential as a wildfire surveillance algorithm providing high frequency (every 10 minutes), multi-resolution fire-line detections. This paper intercompares AHI-FSA across the Northern Territory of Australia (1.4 million km²) over a ten-day period with the well-established fire products from LEO (Low Earth Orbiting) satellites: MODIS (Moderate Resolution Imaging Spectroradiometer) and VIIRS (Visible Infrared Imaging Radiometer Suite). This paper also discusses the difficulties and solutions when comparing high temporal frequency fire products with existing low temporal resolution LEO satellite products. The results indicate that the multi-resolution approach developed for AHI-FSA is successful in mapping fire activity at 500?m. When compared to the MODIS, daily AHI-FSA omission error was only 7%. High temporal frequency data also results in AHI-FSA observing fires, at times, three hours before the MODIS overpass with much-enhanced detail on fire movement.  相似文献