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141.
The Composition of Garnets from Pelitic Schists in relation to the Grade of Regional Metamorphism 总被引:1,自引:0,他引:1
Analyses of garnets are presented from a wide variety of metamorphicterrains, in relation to which there appears to be a regularpattern of substitution of (FeO+MgO) for (CaO+MnO), the valuesof these components reflecting the metamorphic grade of thepelitic schists. This provides a method for indicating variationsin grade in metamorphic terrains and for comparing the variationsin different areas. In areas of repeated metamorphism this wouldappear to have a particular value in establishing the gradeof the various episodes of metamorphism. It is also demonstratedthat by the determination of selected physical propertics (unitcell edge a and refractive index) of garnets in the peliticschists, and evaluating the significance of their variations,it is possible to work out the local changes of metamorphicgrade within a particular area. 相似文献
142.
143.
Nataliia Kussul Andrii Kolotii Sergii Skakun Olena Rakoid Leonid Shumilo 《International Journal of Digital Earth》2020,13(2):309-321
ABSTRACTFor evaluating the progresses towards achieving the Sustainable Development Goals (SDGs), a global indicator framework was developed by the UN Inter-Agency and Expert Group on Sustainable Development Goals Indicators. In this paper, we propose an improved methodology and a set of workflows for calculating SDGs indicators. The main improvements consist of using moderate and high spatial resolution satellite data and state-of-the-art deep learning methodology for land cover classification and for assessing land productivity. Within the European Network for Observing our Changing Planet (ERA-PLANET), three SDGs indicators are calculated. In this research, harmonized Landsat and Sentinel-2 data are analyzed and used for land productivity analysis and yield assessment, as well as Landsat 8, Sentinel-2 and Sentinel-1 time series are utilized for crop mapping. We calculate for the whole territory of Ukraine SDG indicators: 15.1.1 – ‘Forest area as proportion of total land area’; 15.3.1 – ‘Proportion of land that is degraded over total land area’; and 2.4.1 – ‘Proportion of agricultural area under productive and sustainable agriculture’. Workflows for calculating these indicators were implemented in a Virtual Laboratory Platform. We conclude that newly available high-resolution remote sensing products can significantly improve our capacity to assess several SDGs indicators through dedicated workflows. 相似文献
144.
We compare observations of type III impulsive radio bursts made at the Clark Lake Radio Observatory with high-spatial-resolution cinematographic observations taken at the Big Bear Solar Observatory. Use of the log-periodic radio interferometer allows us to localize the radio emission uniquely. This study concentrates on the particularly active region close to the limb on 22 May 1970. Sixteen of the 17 groups were associated with some H activity, 11 of them with the start of such activity.as of September 1972: Williams College-Hopkins Observatory, Williamstown, Massachusetts 01267. 相似文献
145.
Alfvén waves are generated easily in many cosmic plasmas, but they possess no linear damping mechanism since they are not compressive. The most prominent nonlinear damping occurs when one Alfvén wave decays into another plus a slow magnetosonic wave, or two Alfvén waves combine into one fast magnetosonic wave; the resulting magnetosonic waves can then be dissipated. The nonlinear coupling rates are presented, with special emphasis on the astrophysically important case of sound speed Alfvén speed. Streaming cosmic rays generate Alfvén waves moving in the direction of streaming, but they reabsorb the backward moving waves then produced by wave decay. The possible steady states for this system of cosmic rays and Alfvén waves turn out to be highly restricted.Supported by NSF grant GP-15218. 相似文献
146.
Cyril Ponnamperuma 《Icarus》1976,29(2):321-328
In order to understand the chemical processes which may be taking place in the Jovian atmosphere, we have conducted a number of simulation experiments in the laboratory. These reactions appear to be significant for our understanding of chemical evolution and the nature and origin of organic matter in the universe. Mixtures of methane and ammonia in varying proportions have been exposed to electric discharges and the products analyzed. We have found that, as the methane and ammonia disappear, hydrogen cyanide and acetylene are to be built up. The analysis of the volatiles has also provided us with a wide range of aminonitriles. It is conceivable that some of these nitriles, on hydrolysis, will give rise to amino acids. On cyclization, some of them would provide the pathways for the origin of pyrimidines. A characteristic result of these reactions has also been the appearance of a red polymer which may have a bearing on the color in the red spots of Jupiter. Spectral analysis in the laboratory may provide some clues in our search for organic material in the Jovian atmosphere by orbiting spacecraft, or ground-based observations. 相似文献
147.
Kunitomo Sakurai 《Solar physics》1976,47(1):261-266
The magnetic polarity distributions in sunspot groups which produced solar proton flares have been analyzed. It is shown that the fluid motion in sunspot groups and below may be responsible for the origin of inverted or unusual polarity distributions, since rotating motion in these spot groups is often observed. Since such motion seems to produce twisting of magnetic field lines above sunspot groups, the origin of solar flares seems to be closely dependent on instability associated with this twisting of sunspot field lines in the chromosphere and the lower corona. 相似文献
148.
Donat G. Wentzel 《Solar physics》1976,50(2):343-360
I extend a previous paper which argued that Alfvén waves traveling up a large coronal loop may heat this loop at the top and increase its visibility. This heating is now evaluated more completely, taking into account the changes along the loop in field strength, gas density and flux of waves. The location and efficiency of the heating depend very non-linearly on the intensity of the waves, which allows rapid changes in the visibility of a loop. Observational and theoretical conditions for the applicability of the theory are summarized. Alfvén waves preferentially heat the upper portions of coronal helmets, but a measurable excess temperature on a loop requires somewhat implausibly high wave fluxes. Radiation losses from low-lying loops with strong magnetic fields cannot be explained without modifying the theory.The National Center for Atmospheric Research is sponsored by the National Science Foundation. 相似文献
149.
150.
Some properties of solar active regions at 9 and 3.5 mm wavelengths under disturbed conditions are discussed. New regions develop or weak regions intensify at millimeter wavelengths as a result of flares at distant sites. The spectra of the peak flux density of moderately strong bursts observed at 9 mm show a sharp drop toward the shorter millimeter wavelengths. The weak bursts at 3.5 mm manifest mainly as heating phenomena. 相似文献