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141.
Alejandro Ismael Monterroso-Rivas Ana Cecilia Conde-Álvarez José Luís Pérez-Damian Jorge López-Blanco Marcos Gaytan-Dimas Jesús David Gómez-Díaz 《Climatic change》2018,147(3-4):457-473
Vulnerability to climate change was evaluated for three different time periods: 1990, 2000, and 2010. Our objective was to discuss the scope of a multi-temporal assessment of vulnerability. The method used 55 indicators—with emphasis on the agricultural sector in Mexico—of which 27 were updated for the year 2010 and 33 were retrospectively estimated for the year 1990. The results show that in the 20-year study period, the exposure of the municipalities (and inhabitants) has increased, and sensitivity and adaptive capacity have decreased. The number of municipalities vulnerable to climate change declined over the 20-year period. We found that calculating vulnerability by adding exposure and sensitivity and subtracting adaptive capacity (E?+?S???AC) can lead to unintentional underestimation of total vulnerability. When rating vulnerability, care must be taken in what is reported: the results differ for the number of inhabitants versus the number of municipalities. Our previous published vulnerability evaluation was for the year 2000, so we wanted to evaluate the sensitivity of some variables and the vulnerability formula itself we used in that moment. It is possible to evaluate the vulnerability multi-temporally, which allows to evaluate the sensibility and calibration of the variables and indicators used and the reconsideration of their application. 相似文献
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Dolomite in caves: Recent dolomite formation in oxic, non-sulfate environments. Castañar Cave, Spain
Dolomite is a common mineral in the rock record but rare in recent superficial environments. Where it does occur, it is related to anoxic, sulfate-rich environments and microbial activity. The occurrence of some dolomite deposits in caves, however, indicates that dolomite formation is also possible in oxic, non-sulfate settings. Dolomite is forming at 17 °C and in oxic-vadose conditions on the host rocks and aragonite speleothems of the Castañar Cave, Cáceres, Spain. It appears as spheroids and dumbbells 50–300 μm in diameter that internally consist of micron-sized rhombic to rounded crystals. Initially this dolomite is Ca-rich, non-stoichiometric and poorly ordered. Mg-rich solutions allow the precipitation of metastable Mg-rich carbonates, such as huntite. This soon transforms into this Ca-rich dolomite, which later “ages” to form a more stoichiometric dolomite. These dolomites show similarities to those grown under anoxic, sulfate-rich conditions and their presence in caves provides a different setting that may contribute to the understanding of the “dolomite problem”, including their initial formation and later recrystallization processes. 相似文献
145.
Galileo Constellation Design 总被引:2,自引:0,他引:2
Álvaro Mozo-García Esperanza Herráiz-Monseco Ana Belén Martín-Peiró Miguel M. Romay-Merino 《GPS Solutions》2001,4(4):9-15
A significant effort has been carried out in Europe to define the European Global Navigation Satellite System (GNSS), named
Galileo Satellites flying in Medium Earth Orbits (MEO) will compose the system (according to the most recent architecture
definition baseline); a regional complement of geosynchronous satellites may be required to increase performances over Europe
and maybe also to provide some specific communication services. Nominal medium performances are envisaged, but they will be
increased by means of augmentation systems (local or wide area), or even by using simultaneously other GNSSs such as GPS.
All the involved requirements make the design process quite complex. A powerful software tool, Elcano, has been developed
for this purpose; its capabilities will be outlined, and the results of the design process will be presented. ? 2001 John
Wiley & Sons, Inc. 相似文献
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Tomàs Artés Andrés Cencerrado Ana Cortés Tomàs Margalef 《International journal of geographical information science》2016,30(3):594-611
AbstractForest fires are a kind of natural hazard with a high number of occurrences in southern European countries. To avoid major damages and to improve forest fire management, one can use forest fire spread simulators to predict fire behavior. When providing forest fire predictions, there are two main considerations: accuracy and computation time. In the context of natural hazards simulation, it is well known that part of the final forecast error comes from uncertainty in the input data. These data typically consist of a set of GIS files, which should be appropriately conflated. For this reason, several input data calibration methods have been developed by the scientific community. In this work, the Two-Stage calibration methodology, which has been shown to provide good results, is used. This calibration strategy is computationally intensive and time-consuming because it uses a Genetic Algorithm as a solution. Taking into account the aspect of urgency in forest fire spread prediction, it is necessary to maintain a balance between accuracy and the time needed to calibrate the input parameters. In order to take advantage of this technique, one must deal with the problem that some of the obtained solutions are impractical, since they involve simulation times that are too long, preventing the prediction system from being deployed at an operational level. A new method which finds the minimum resolution reduction for such long simulations, keeping accuracy loss to a known interval, is proposed. The proposed improvement is based on a time-aware core allocation policy that enables real-time forest fire spread forecasting. The final prediction system is a cyberinfrastructure, which enables forest fire spread prediction at real time. 相似文献
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