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1.
Marek Biesiada 《Astrophysics and Space Science》2003,283(4):511-516
Theory of dynamical systems offers a possibility of investigating the space of all possible solutions. In the context of simple
cosmological models such like Varying Speed of Light Friedman-Robertson-Walker (VSL FRW) models there exists a systematic
method of reducing field equations to certain two-dimensional dynamical system. One of the features of this reduction is the
possibility of representing the model as a Hamiltonian system in which the properties of the potential function V(X) can serve as a tool for qualitative classification of possible evolutions of a(t). Some important features like resolution of the flatness problem, existence of event horizons near the singularity can be
visualized as domains on the phase-space. Then one is able to see how large is the class of solutions (labelled by the initial
conditions) leading to the desired property.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
2.
Analyses of primary and early diagenetic fluid inclusions in the halite from the Late Ordovician Mallowa Salt, Canning Basin, Western Australia indicate a Ca‐rich composition and high concentration of parent brines in the basin which were close to sylvite and carnallite precipitation. The salt‐bearing series in the sampled interval was overheated up to 62 °C. The recorded differences in gas compositions result from the input of several gas sources including dispersed organic matter in the salt series and hydrocarbon deposits in the underlying rocks. The high concentration of the brines in fluid inclusions does not allow quantitative reconstruction of the chemical composition of Late Ordovician parent seawater. Using the information from Early Cambrian and Late Silurian basins as a proxy, however, the new data indicate that Late Ordovician seawater was undoubtedly Ca‐rich and, in comparison with modern seawater, had a similar K content, considerably lower Mg content (c. 30%), approximately three times the Ca content and one‐third the SO4 content. 相似文献
3.
The variability of ruthenium in chromite from chassignite and olivine‐phyric shergottite meteorites: New insights into the behavior of PGE and sulfur in Martian magmatic systems 下载免费PDF全文
Raphael J. Baumgartner Marco L. Fiorentini David Baratoux Ludovic Ferrière Marek Locmelis Andrew Tomkins Kerim A. Sener 《Meteoritics & planetary science》2017,52(2):333-350
The Martian meteorites comprise mantle‐derived mafic to ultramafic rocks that formed in shallow intrusions and/or lava flows. This study reports the first in situ platinum‐group element data on chromite and ulvöspinel from a series of dunitic chassignites and olivine‐phyric shergottites, determined using laser‐ablation ICP‐MS. As recent studies have shown that Ru has strongly contrasting affinities for coexisting sulfide and spinel phases, the precise in situ analysis of this element in spinel can provide important insights into the sulfide saturation history of Martian mantle‐derived melts. The new data reveal distinctive differences between the two meteorite groups. Chromite from the chassignites Northwest Africa 2737 (NWA 2737) and Chassigny contained detectable concentrations of Ru (up to ~160 ppb Ru) in solid solution, whereas chromite and ulvöspinel from the olivine‐phyric shergottites Yamato‐980459 (Y‐980459), Tissint, and Dhofar 019 displayed Ru concentrations consistently below detection limit (<42 ppb). The relatively elevated Ru signatures of chromite from the chassignites suggest a Ru‐rich (~1–4 ppb) parental melt for this meteorite group, which presumably did not experience segregation of immiscible sulfide liquids over the interval of mantle melting, melt ascent, and chromite crystallization. The relatively Ru‐depleted signature of chromite and ulvöspinel from the olivine‐phyric shergottites may be the consequence of relatively lower Ru contents (<1 ppb) in the parental melts, and/or the presence of sulfides during the crystallization of the spinel phases. The results of this study illustrate the significance of platinum‐group element in situ analysis on spinel phases to decipher the sulfide saturation history of magmatic systems. 相似文献
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The microstructure and some physico-mechanical properties of Beardsley and Faith, both H5 chondrites, were compared. Although the bulk sample porosities are respectively 9.1% and 14.5%, suggesting lower consolidation of Faith, the effective porosities are 5.63% and 1.79%—much higher for Beardsley. The material of Faith, characterized by vugs, vesicles and closed channels—abundant but all sized below 0.01 μm—is of higher strength than that of Beardsley, where joints, fissures, open channels and microcracks are sized from 0.1 to 10 μm. The higher elastic properties of Faith are shown by the velocity of the compressional wave of 6.66 km s−1 against that of 5.12 km s−1 for Beardsley. An example of physical diversity among chondrites to the same chemical-petrologic type is therefore demonstrated. 相似文献
7.
Tomasz Mrozek Szymon Gburek Marek Siarkowski Barbara Sylwester Janusz Sylwester Anna Kepa Magdalena Gryciuk 《Solar physics》2018,293(7):101
In 2009, the Russian Complex Orbital Observations Near-Earth of Activity of the Sun (CORONAS-Photon) spacecraft was launched, carrying the Polish Solar PHotometer In X-rays (SphinX). The SphinX was most sensitive in the spectral range 1.2?–?15 keV, thus an excellent opportunity appeared for comparison with the low-energy end of Ramaty High Energy Solar Spectroscopic Imager (RHESSI) spectra. Common spectral measurements with these instruments cover the range where most of the flare energy is accumulated. We have chosen four consecutive small solar events observed on 4 July 2009 at 13:43 UT, 13:48 UT, 13:52 UT, and 13:55 UT (RHESSI flare peak times) and used them to compare the data and results from the two instruments. Moreover, we included Geostationary Operational Environmental Satellite (GOES) records in our analysis. In practice, the range of comparison performed for SphinX and RHESSI is limited roughly to 3?–?6 keV. RHESSI fluxes measured with a use of one, four, and nine detectors in the 3?–?4 keV energy band agree with SphinX measurements. However, we observed that SphinX spectral irradiances are three times higher than those of RHESSI in the 4?–?6 keV energy band. This effect contributes to the difference in obtained emission measures, but the derived temperatures of plasma components are similar. RHESSI spectra were fitted using a model with two thermal components. We have found that the RHESSI hot component is in agreement with GOES, and the RHESSI hotter component fits the SphinX flaring component well. Moreover, we calculated the so-called thermodynamic measure and the total thermal energy content in the four microflares that we studied. The results obtained show that SphinX is a very sensitive complementary observatory for RHESSI and GOES. 相似文献
8.
Marek Szczotka 《Ocean Engineering》2010,37(7):539-548
Dynamic and quasi-static models for analysis of a pipe lay spread are presented in the paper. Depending on the type of a pipe, spooling it on a big drum (reel) may cause plastic deformations. When the pipe is reeled out at sea, again it undergoes plastic deformations. In order to model such a nonlinear behaviour, a model, which includes both elasto-plastic material characteristics and large deformations, is required. Discretisation of the pipe is performed by means of the Rigid Finite Element Method (RFEM), which allows us to study static and dynamic problems, taking into account required properties of the model. Different sea conditions are simulated and analysed. It is shown how operational conditions can limit the ability of laying operation by a dedicated vessel, due to an unstable system response. The second part of the paper presents an upgrade of a passive reel drive by application of an active drive. In the model used for control applications, the pipe is modelled by a neural network. This allows us to perform a real-time calculations. In this fast-response calculation model, nonlinear aspects of the system are taken into account. The improvements in a pipe laying vessel performance are presented by some results of numerical simulations. The conclusions are also formulated. 相似文献
9.
Mariusz Majdaski Elena Kozlovskaya Marek Grad SUDETES Working Group 《Tectonophysics》2007,437(1-4):17-36
The SUDETES 2003 wide-angle refraction/reflection experiment covered the area of the south-western Poland and the northern Bohemian Massif. The good quality data that were gathered combined with the data from previous experiments (POLONAISE'97, CELEBRATION 2000) allowed us to prepare a 3D seismic model of the crust and uppermost mantle for this area. We inverted travel times of both refracted and reflected P waves using the JIVE3D package. This allowed us to obtain a model of P-wave velocity distribution as well as the shape of major boundaries in the crust. We also present a detailed uncertainty analysis for both the boundary depths and the velocity field. In doing the uncertainty analysis we found an interesting, strong dependence between uncertainty and inversion scheme (order of used phases). We also compared the model with surface geology and found good correlation between velocity inhomogeneities in the uppermost crust (down to 2 km) and major geological units. The higher velocity lower crust (6.9–7.2 km/s) could result from remelting of the lower crust or magmatic underplating. 相似文献
10.
Andrzej W. Wernik Mariusz Pożoga Marcin Grzesiak Andrzej Rokicki Marek Morawski 《Acta Geophysica》2008,56(4):1129-1146
As a partial contribution to the International Polar Year, the Space Research Centre of the Polish Academy of Sciences has
installed on the Polish Polar Station, located in the region of the Hornsund Bay in southern Spitsbergen, the equipment intended
to monitor ionospheric scintillation and total electron content. We describe the equipment setup and the aims of the experiment.
As an illustration of data analysis, we present the reconstruction of irregular structure of the ionosphere from the complex
amplitude data, and the estimate of the form and drift of diffraction pattern based on the spaced receiver measurements. 相似文献