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91.
From the assumption of symmetry of ratio of Fermion masses and masses of bosons ratio results the hypothetical mass of quark-lepton bosonm
wes and hypothetical mass of electron neutrinom
ve. 相似文献
92.
From the observed present parameters of the Universe and the model properties of an expansive non-decelerative universe it results that the value of Boltzmann's constant (coefficient)k does not change only before the end of radiation era, but also in the matter era; with the increase of gauge factora, it decreases as (a
–1)1/4. 相似文献
93.
Sheridan Michael F. Hubbard Bernard Carrasco-núñez Gerardo Siebe Claus 《Natural Hazards》2004,33(2):209-221
Volcán Citlaltépetl (Pico de Orizaba) with an elevation of 5,675 m is the highest volcano in North America. Its most recent catastrophic events involved the production of pyroclastic flows that erupted approximately 4,000, 8,500, and 13,000 years ago. The distribution of mapped deposits from these eruptions gives an approximate guide to the extent of products from potential future eruptions. Because the topography of this volcano is constantly changing computer simulations were made on the present topography using three computer algorithms: energy cone, FLOW2D, and FLOW3D. The Heim Coefficient (), used as a code parameter for frictional sliding in all our algorithms, is the ratio of the assumed drop in elevation (H) divided by the lateral extent of the mapped deposits (L). The viscosity parameter for the FLOW2D and FLOW3D codes was adjusted so that the paths of the flows mimicked those inferred from the mapped deposits. We modeled two categories of pyroclastic flows modeled for the level I and level II events. Level I pyroclastic flows correspond to small but more frequent block-and-ash flows that remain on the main cone. Level II flows correspond to more widespread flows from catastrophic eruptions with an approximate 4,000-year repose period. We developed hazard maps from simulations based on a National Imagery and Mapping Agency (NIMA) DTED-1 DEM with a 90 m grid and a vertical accuracy of ±30 m. Because realistic visualization is an important aid to understanding the risks related to volcanic hazards we present the DEM as modeled by FLOW3D. The model shows that the pyroclastic flows extend for much greater distances to the east of the volcano summit where the topographic relief is nearly 4,300 m. This study was used to plot hazard zones for pyroclastic flows in the official hazard map that was published recently. 相似文献
94.
J.?Escuder-VirueteEmail author R.?Carbonell C.?Pérez-Soba D.?Martí A.?Pérez-Estaún 《International Journal of Earth Sciences》2004,93(2):172-188
The structure of a fault zone developed in granitic rocks can be established on the basis of the spatial variability of geological, geophysical and geochemical parameters. In the North Fault of the Mina Ratones area (SW Iberian Massif, Spain), fault rocks along two studied traverses (SR-2 and SR-3 boreholes) exhibit systematic changes in mineralogy, geochemistry, fabrics and microstructures that are related to brittle deformation and alteration of granite to form cataclasite and subsequent gouge. The spatial distribution and intensity of these changes suggest a North Fault morphology that is consistent with the fault-core/damage-zone model proposed by Chester et al. (1993) to describe a fault zone architecture. North Fault damage zone thickness can be defined by the development of mechanically related mesoscopic faults and joints, that produce a Fracture Index (FI)>10. High FI values are spatially correlated with relative low seismic velocity zones (VP<5 km/s and VS<2.5 km/s in the well-logs), more probably related to a high concentration of fractures and geochemical alteration produced by meteoric water-granite interaction along fault surfaces. This correlation is the base of a geostatistical model proposed in the final part of this study to image the fault zone architecture of a granitic massif. 相似文献
95.
96.
Although there is a consensus on the necessity of monitoring solid wastes pollution on beaches, the methods applied vary widely. Therefore, creating, testing and recommending a method that not only allows comparisons of places and periods, but also the detection of source signals, will be important to reach the objectives of the source-prevention principle. This will also allow the optimisation of time, resources, and processing of samples and data. A classification of the items found into specific categories was made according to their most probable source/use (fisheries, food packaging, hazardous, sewage/personal hygiene, beach user, general home). This study tested different widths of sampling transects to be used in the detection of plastics contamination on beaches, until all the categories were significantly represented. Each transect had its total width (50m) sub-divided into eight intervals of 0-2.5m; 2.5-5m; 5-10m; 10-15m; 15-20m; 20-30m; 30-40m; and 40-50m. The accumulated number of categories in the 50m (up to 2.5m; up to 5m and so on) was used to determine the minimal width necessary to qualitatively characterize the area regarding plastics contamination. The diversity of the categories was directly related to the area of the sampling transect. These results indicate that a significant increase in the number of categories in the first intervals tend to stabilize from 15-20m onwards. 相似文献
97.
Downslope windstorms at Kvísker in Southeast Iceland are explored using a mesoscale model, observations and numerical analysis of the atmosphere. Two different types of gravity-wave induced windstorms are identified. At the surface, their main difference is in the horizontal extent of the lee-side accelerated flow. Type S (Short) is a westerly windstorm, which is confined to the lee-slopes of Mount ?r?faj?kull, while a Type E (Extended) windstorm occurs in the northerly flow and is not confined to the lee-slopes but continues some distance downstream of the mountain. The Type S windstorm may be characterized as a more pure gravity-wave generated windstorm than the Type E windstorm which bears a greater resemblance to local flow acceleration described by hydraulic theory. The low-level flow in the Type E windstorm is of arctic origin and close to neutral with an inversion well above the mountain top level. At middle tropospheric levels there is a reverse vertical windshear. The Type S windstorm occurs in airmasses of southerly origin. It also has a well-mixed, but a shallower boundary-layer than the Type E windstorms. Aloft, the winds increase with height and there is an amplified gravity wave. Climate projections indicate a possible decrease in windstorm frequency up to the year 2050. 相似文献
98.
Extreme rainfalls in SE South America 总被引:1,自引:0,他引:1
Heavy rainfall trends in a region of south-eastern South America during 1959–2002 were discussed using daily data of 52 meteorological stations of Argentina, Brazil and Uruguay. Changes in intensity and frequency were both studied with different statistical tests and approaches to check the significance of trends of single and regional aggregated rainfall series. There were predominant positive trends in the annual maximum rainfalls, as well as a remarkable increment in the frequency of heavy rainfalls over thresholds ranging from 50 to 150 mm. However, significant positive trends were not shown in the series of annual maximums and shown only in 15% to 30% of the series of frequencies over thresholds. This lack of significance is due to the high variability of heavy rainfalls in space and time, which makes difficult their capture by single rain gauges. Thus, when the assessment of the heavy rainfall indicators of intensity and frequency were conducted at the regional and sub-regional level, it showed significant trends, both in intensity and frequency over thresholds, with a clearer signal in central and eastern Argentina between 30° and 40° S. 相似文献
99.
Daniel Higuero Juan M. Tirado Jesús Carretero Fernando Félix Antonio de la Fuente 《Astrophysics and Space Science》2009,321(3-4):169-175
Institutions such as NASA, ESA or JAXA find solutions to distribute data from their missions to the scientific community, and their long term archives. This is a complex problem, as it includes a vast amount of data, several geographically distributed archives, heterogeneous architectures with heterogeneous networks, and users spread around the world. We propose a novel architecture that solves this problem aiming to fulfill the requirements of the final user. Our architecture is a modular system that provides a highly efficient parallel multiprotocol download engine, using a publisher/subscriber policy which helps the final user to obtain data of interest transparently. We have evaluated a first prototype, in collaboration with the ESAC centre in Villafranca del Castillo (Spain) that shows a high scalability and performance, opening a wide spectrum of opportunities. 相似文献
100.
Jesús López H. Fabio Bresolin Elena Terlevich Roberto Terlevich Daniel Rosa-González 《Astrophysics and Space Science》2009,324(2-4):351-354
We present preliminary results obtained from integral-field (IFU) data of the giant extragalactic Hii region NGC5461, located in a spiral arm (RA=14h03m41.4s, dec=+54°19′05″) of M101. The spatial and spectral information obtained with IFUs allows us to decompose the Hii region and analyze it at high resolution. 相似文献