排序方式: 共有39条查询结果,搜索用时 31 毫秒
1.
2.
Astronomy Reports - A large fraction of the energy released during the gravitational collapse of the core of a massive star is carried by neutrinos. Neutrinos play the main role in explaining... 相似文献
3.
T. M. Lenton R. Marsh A. R. Price D. J. Lunt Y. Aksenov J. D. Annan T. Cooper-Chadwick S. J. Cox N. R. Edwards S. Goswami J. C. Hargreaves P. P. Harris Z. Jiao V. N. Livina A. J. Payne I. C. Rutt J. G. Shepherd P. J. Valdes G. Williams M. S. Williamson A. Yool 《Climate Dynamics》2007,29(6):591-613
We have used the Grid ENabled Integrated Earth system modelling (GENIE) framework to undertake a systematic search for bi-stability
of the ocean thermohaline circulation (THC) for different surface grids and resolutions of 3-D ocean (GOLDSTEIN) under a 3-D
dynamical atmosphere model (IGCM). A total of 407,000 years were simulated over a three month period using Grid computing.
We find bi-stability of the THC despite significant, quasi-periodic variability in its strength driven by variability in the
dynamical atmosphere. The position and width of the hysteresis loop depends on the choice of surface grid (longitude-latitude
or equal area), but is less sensitive to changes in ocean resolution. For the same ocean resolution, the region of bi-stability
is broader with the IGCM than with a simple energy-moisture balance atmosphere model (EMBM). Feedbacks involving both ocean
and atmospheric dynamics are found to promote THC bi-stability. THC switch-off leads to increased import of freshwater at
the southern boundary of the Atlantic associated with meridional overturning circulation. This is counteracted by decreased
freshwater import associated with gyre and diffusive transports. However, these are localised such that the density gradient
between North and South is reduced tending to maintain the THC off state. THC switch-off can also generate net atmospheric
freshwater input to the Atlantic that tends to maintain the off state. The ocean feedbacks are present in all resolutions,
across most of the bi-stable region, whereas the atmosphere feedback is strongest in the longitude–latitude grid and around
the transition where the THC off state is disappearing. Here the net oceanic freshwater import due to the overturning mode
weakens, promoting THC switch-on, but the atmosphere counteracts this by increasing net freshwater input. This increases the
extent of THC bi-stability in this version of the model.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
4.
N. V. Chukanov S. M. Aksenov R. K. Rastsvetaeva K. V. Van D. I. Belakovskiy I. V. Pekov V. V. Gurzhiy W. Schüller B. Ternes 《Geology of Ore Deposits》2015,57(8):721-731
A new mineral, mendigite (IMA no. 2014-007), isostructural with bustamite, has been found in the In den Dellen pumice quarry near Mendig, Laacher Lake area, Eifel Mountains, Rhineland-Palatinate (Rheinland-Pfalz), Germany. Associated minerals are sanidine, nosean, rhodonite, tephroite, magnetite, and a pyrochlore-group mineral. Mendigite occurs as clusters of long-prismatic crystals (up to 0.1 × 0.2 × 2.5 mm in size) in cavities within sanidinite. The color is dark brown with a brown streak. Perfect cleavage is parallel to (001). D calc = 3.56 g/cm3. The IR spectrum shows the absence of H2O and OH groups. Mendigite is biaxial (–), α = 1.722 (calc), β = 1.782(5), γ = 1.796(5), 2V meas = 50(10)°. The chemical composition (electron microprobe, mean of 4 point analyses, the Mn2+/Mn3+ ratio determined from structural data and charge-balance constraints) is as follows (wt %): 0.36 MgO, 10.78 CaO, 37.47 MnO, 2.91 Mn2O3, 4.42 Fe2O3, 1.08 Al2O3, 43.80 SiO2, total 100.82. The empirical formula is Mn2.00(Mn1.33Ca0.67) (Mn0.50 2+ Mn0.28 3+ Fe0.15 3+ Mg0.07)(Ca0.80 (Mn0.20 2+)(Si5.57 Fe0.27 3+ Al0.16O18). The idealized formula is Mn2Mn2MnCa(Si3O9)2. The crystal structure has been refined for a single crystal. Mendigite is triclinic, space group \(P\bar 1\); the unit-cell parameters are a = 7.0993(4), b = 7.6370(5), c = 7.7037(4) Å, α = 79.58(1)°, β = 62.62(1)°, γ = 76.47(1)°; V = 359.29(4) Å3, Z = 1. The strongest reflections on the X-ray powder diffraction pattern [d, Å (I, %) (hkl)] are: 3.72 (32) (020), 3.40 (20) (002, 021), 3.199 (25) (012), 3.000 (26), (\(01\bar 2\), \(1\bar 20\)), 2.885 (100) (221, \(2\bar 11\), \(1\bar 21\)), 2.691 (21) (222, \(2\bar 10\)), 2.397 (21) (\(02\bar 2\), \(21\bar 1\), 203, 031), 1.774 (37) (412, \(3\bar 21\)). The type specimen is deposited in the Fersman Mineralogical Museum, Russian Academy of Sciences, Moscow, registration number 4420/1. 相似文献
5.
Dyment L. N. Aksenov P. V. Losev S. M. Porubaev V. S. 《Izvestiya Atmospheric and Oceanic Physics》2021,57(9):1081-1086
Izvestiya, Atmospheric and Oceanic Physics - The values of the characteristics of ice-cover leads in the Laptev and East Siberian Seas calculated from satellite images with spatial resolution of... 相似文献
6.
V. I. Aksenov N. G. Bubnov G. I. Klinova A. V. Iospa S. G. Gevorkyan 《Water Resources》2011,38(7):934-943
The impact of mineralized water on frozen soil causes dissolution of ice contained in the latter, resulting in cooling of
the frozen soil. 相似文献
7.
S. A. Ananyev S. I. Konovalenko R. K. Rastsvetaeva S. M. Aksenov N. V. Chukanov A. N. Sapozhnikov V. E. Zagorsky A. A. Virus 《Geology of Ore Deposits》2011,53(8):751-757
A new mineral species has been discovered at the calc-skarnoid occurrence near the mouth of the Tashelga River, Kuznetsky
Alatau, Gorny Shoria, Russia, and named after the locality of its discovery. Associated minerals are calcite, hibonite, grossular,
vesuvianite, hercynite, magnetite, corundum, perovskite, scapolite, diopside, and apatite. The new mineral occurs as prismatic
or finely fibrous crystals up to 1.5–2.0 mm in length, their parallel intergrowths, and felty aggregates as large as 10 mm
across. Tashelgite is bluish green, translucent to transparent, with vitreous luster; D
calc = 3.67 g/cm3. The IR spectrum does not contain bands of OH groups. Tashelgite is biaxial (−), with α = 1.736(2), β = 1.746(2), γ = 1.750(2);
2V
meas = −20(2)°. Dispersion is strong, r < ν. Pleochroism is distinct: X (blue-green) > Y (yellowish green) > Z (almost colorless). Chemical composition (electron microprobe, average of five-point analyses, Fe2O3 is estimated from the ratio of intensities I(FeKb5 )/I(FeKb1 )I(Fe_{K\beta _5 } )/I(Fe_{K\beta _1 } ) in the X-ray spectrum, H2O was determined as a weight loss on heating in vacuum up to 1000°C), wt %: 7.98 CaO, 6.75 MgO, 0.45 MnO, 11.32 FeO, 1.40
Fe2O3, 70.70 Al2O3, 1.8(2) H2O, 100.40 in total. The empirical formula calculated on the basis of 17 oxygen atoms is H1.27Ca0.90Mg1.06Mn0.04 Fe1.002+Fe0.113+Al8.80O17.00. The idealized formula is CaMgFe2+Al9O16(OH). According to single-crystal X-ray structural data, tashelgite is monoclinic, pseudoorthorhombic, space group Pc; unit cell parameters are: a = 5.6973(1), b = 17.1823(4), c = 23.5718(5)?; β = 90.046(3)°; V = 2307.5(1)?3, Z = 8. The crystal structure of tashelgite is unique and characterized by ordering of all cations; Al occupies sites with octahedral
and tetrahedral coordination. The cation ordering has also been confirmed by IR spectroscopy. The strongest lines of the X-ray
powder diffraction pattern (d, ?]-I[hkl] are: 11.79–48 [002], 2.845–43 [061], 2.616–100 [108], 2.584–81 [146], 2.437–44 [163], 2.406–61 [057], 2.202–72 [244]. The
type specimen of tashlegite has been deposited at the Fersman Mineralogical Museum of the Russian Academy of Sciences, Moscow,
Russia. 相似文献
8.
N. V. Chukanov R. K. Rastsvetaeva S. M. Aksenov I. V. Pekov D. I. Belakovskiy G. Blass G. Möhn 《Geology of Ore Deposits》2013,55(8):663-668
A new mineral, lahnsteinite, has been found in the dump of the Friedrichssegen Mine, Bad Ems district, Rhineland-Palatinate (Rheinland-Pfalz), Germany. Lahnsteinite, occurring as colorless tabular crystals in the cavities of goethite, is associated with pyromorphite, hydrozincite, quartz, and native copper. The Mohs’ hardness is 1.5; the cleavage is perfect parallel to (001). D calc = 2.995 g/cm3, D meas = 2.98(2) g/cm3. The IR spectrum is given. The new mineral is optically biaxial, negative, α = 1.568(2), β = 1.612(2), γ = 1.613(2), 2V meas = 18(3)°, 2V calc = 17°. The chemical composition (wt %, electron microprobe data; H2O was determined by gas chromatography of ignition products) is as follows: 3.87 FeO, 1.68 CuO, 57.85 ZnO, 15.83 SO3, 22.3 H2O, total is 101.53. The empirical formula is (Zn3.3Fe0.27Cu0.11)Σ3.91(S0.98O4)(OH)5 · 3H2.10O. The crystal structure has been studied on a single crystal. Lahnsteinite is triclinic, space group P1, a = 8.3125(6), b = 14.545(1), c = 18.504(2) Å, α = 89.71(1), β = 90.05(1), γ = 90.13(1)°, V = 2237.2(3) Å3, Z = 8. The strong reflections in the X-ray powder diffraction pattern [d, Å (I, %)] are: 9.30 (100), 4.175 (18), 3.476 (19), 3.290 (19), 2.723 (57), 2.624 (36), 2.503 (35), 1.574 (23). The mineral has been named after its type locality near the town of Lahnstein. The type specimen of lahnsteinite is deposited in the Fersman Mineralogical Museum of the Russian Academy of Sciences, Moscow, registration number 4252/1. 相似文献
9.
The roles of neutrinos and convective instability in collapsing supernovae are considered. Spherically symmetrical computations of the collapse using the Boltzmann equation for the neutrinos lead to the formation of the condition of convective instability, \({\left( {\frac{{\partial P}}{{\partial s}}} \right)_{\rho {Y_l}}}\frac{{ds}}{{dr}} + {\left( {\frac{{\partial P}}{{\partial {Y_L}}}} \right)_{\rho s}}\frac{{d{Y_L}}}{{dr}}\) < 0, in a narrow region of matter accretion above the neutrinosphere. If instability arises in this region, the three-dimensional solution will represent a correction to the spherically symmetrical solution for the gravitational collapse. The mean neutrino energies change only negligibly in the narrow region of accretion. Nuclear statistical equilibrium is usually assumed in the hot proto-neutron stellar core, to simplify the computations of the collapse. Neutronization with the participation of free neutrons is most efficient. However, the decay of nuclei into nucleons is hindered during the collapse, because the density grows too rapidly compared to the growth in the temperature, and an appreciable fraction of the energy is carried away by neutrinos. The entropy of the matter per nucleon is modest at the stellar center. All the energy is in degenerate electrons during the collapse. If the large energy of these degenerate electrons is taken into account, neutrons are efficiently formed, even in cool matter with reduced Ye (the difference between the numbers of electrons and positrons per nucleon). This process brings about an increase in the optical depth to neutrinos, the appearance of free neutrons, and an increase in the entropy per nucleon at the center. The convectively unstable region at the center increases. The development of large-scale convection is illustrated using a multi-dimensional gas-dynamical model for the evolution of a stationary, unstable state (without taking into account neutrino transport). The time for the development of convective instability (several milliseconds) does not exceed the time for the existence of the unstable region at the center (10ms). The realization of this type of instability is fundamentally different from a spherically symmetrical model. The flux of neutrinos changes and the mean energy of the neutrinos is increased, which has important implications for the detection of neutrinos from supernovae. For these same reasons, the energy absorped in the supernova envelope also changes in the transition to such a multi-dimensional model. 相似文献
10.
—The results of the frequency analysis of seismoacoustic elastic waves radiated from the loaded rock sample source models and of rock bursts records are presented. For both categories of study the fundamental symptoms of nonlinear processes in seismic foci were found and demonstrated. Namely, the wave-field modulation (satellites in the spectra), forced synchronisation (spectra simplification and their transformation into a narrow spectral band), frequency shift to lower values and, finally, coherency of radiation. A new method of amplitude-phase distribution is worked out. All this indicates that nonlinear processes can participate in a seismic source during the energy release. Also, the disagreement between the source sizes observed in the nature and computed by means of linear physics, can be explained by self-organising processes. 相似文献