Statistical Distribution Laws for Metallic Mineral Deposit Sizes     

Alberto E. Patiño Douce 《Natural Resources Research》2016,25(4):365-387

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Analysis and Classification of Natural Rock Textures based on New Transform-based Features     

Rodrigo Lobos  Jorge F. Silva  Julián M. Ortiz  Gonzalo Díaz  Alvaro Egaña 《Mathematical Geosciences》2016,48(7):835-870

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Model for the Processing and Estimation of Dual Frequency Echo Sounder Observations in Detailed Bathymetries   总被引：1，自引：0，他引：1  

Raúl Pereda García  Felipe Piña García  Julio Manuel De Luis Ruiz  Raúl Husillos Rodríguez 《Marine Geodesy》2016,39(3-4):305-320

The dataset acquired by an echo sounder generally comprises outliers and erroneous measurements which must be automatically processed. The main aim of this research is the development and validation of an algorithm which permits detecting outliers, estimating their real value from data acquired with a multifrequency echo sounder, and verifying the measure according to the desired accuracy. The process considers the nature of the seabed and improves the density and number of lectures without globally compromising the precision, but enhancing it in areas with anomalous measurements. Twenty-nine percent of this type of measurements, which would have been otherwise rejected, have been estimated.  相似文献   

Self-organization maps (SOM) in the definition of a “transfer function” for a diatoms-based climate proxy     

Acevedo-Acosta  Juan David  Martínez-López  Aída  Morales-Acoltzi  Tomás  Albáñez-Lucero  Mirtha  Verdugo-Díaz  Gerardo 《Climate Dynamics》2021,56(1-2):423-437

Climate Dynamics - This study utilizes self-organizing maps (SOM) —a particular type of artificial neural network (ANN) — as a nonlinear analysis tool for identifying species that can...  相似文献   

Daily, weekly and seasonal relationships among VOCs, NOx x and O3 in a semi-urban area near Barcelona     

I. Filella  J. Peñuelas 《Journal of Atmospheric Chemistry》2006,54(2):189-201

Daily, weekly, and seasonal patterns of O₃, NOx _x and VOCs and their relationship to meteorological conditions were studied in a semi-urban site near Barcelona by means of five-day long campaigns that included weekend and labor days in December, March, June, and October. The plant protection thresholds for ozone and NO₂ were exceeded, respectively, on all the studied days in summer and on all the studied days. Ozone formation was predominantly local and relied on photochemical processes with VOCs playing a controlling role. Formaldehyde, acetaldehyde, methanol, toluene, isoprene, and acetone (in this order) presented the highest O₃ formation potential during the studied periods. These results highlight the important role in O₃ formation played by VOC species such as acetaldehyde, methanol, and acetone, that all have a significant biogenic component. Thus, these VOCs must be taken into account in the discussion of any ozone abatement strategy.  相似文献   

Paleolimnological evidence of Holocene climatic changes in Lake Blanca, southern Uruguay     

L. del Puerto  F. García-Rodríguez  H. Inda  R. Bracco  C. Castiñeira  J. B. Adams 《Journal of Paleolimnology》2006,36(2):151-163

Paleolimnological data are presented on Holocene climatic changes in Lake Blanca, a small (0.6 km²), coastal fresh waterbody in southern Uruguay. Using a sediment core that extended to 7,300 year BP, analyses of pooid, panicoid and chloridoid phytoliths (Poaceae) allowed us to identify 16 Opal Phytoliths Association Zones (OPAZ). Both temperature and humidity indices were calculated from relative percentages of opal phytoliths and the climatic trends were inferred. During the early Holocene, prior to the first Holocene marine transgression (∼ ∼8,000–7,000 yr BP), cool-arid climatic conditions were inferred. After the first Holocene transgression, predominance of cool-humid conditions was registered until about 4,000 yr BP. A transition from cool-semiarid/arid to alternate warm-temperate and humid-very-humid conditions was detected for ∼∼4,000–1,000 yr BP. Increases in trophic state were observed because of such a climatic amelioration. After ∼ ∼1,000 yr BP, a shift from warm to temperate and cool temperatures was inferred. Such a cooling episode was assigned to a “LIA” which took place by the end of the 18th century and the beginning of the 19th century. A decrease in trophic state was observed during this climatic deterioration. After such a little ice age, present temperate humid conditions were established. The humidity indices calculated from relative percentages of opal phytoliths for the last ∼ ∼70 years were compared to annual rainfall data. Such a comparison showed that opal phytoliths are reliable indicators of humidity.  相似文献   

Notes on Notiosorex crawfordi (coues) from two oases in the Baja California peninsula, México     

S.T. lvarez-Castaeda  M.M. Correa-Ramírez  A.L. Trujano-lvarez 《Journal of Arid Environments》2006,66(4):773-777

Data from distribution, ecology, and stomach contents of four desert shrews, Notiosorex crawfordi (Coues), collected from a large gap in their known distribution on the Baja California peninsula, in Mexico is presented in this paper. The contents in the stomach were specimens of the order Araneae, Hymenoptera, Coleoptera, Dictioptera, and Acari, and small quantities of plant material were also found.  相似文献   

A disaster risk management performance index   总被引：2，自引：4，他引：2  

Martha Liliana Carreño  Omar Darío Cardona  Alex H. Barbat 《Natural Hazards》2007,41(1):1-20

The Risk Management Index, RMI, proposed in this paper, brings together a group of indicators that measure risk management performance and effectiveness. These indicators reflect the organizational, development, capacity and institutional actions taken to reduce vulnerability and losses in a given area, to prepare for crisis and to recover efficiently from disasters. This index is designed to assess risk management performance. It provides a quantitative measure of management based on predefined qualitative targets or benchmarks that risk management efforts should aim to achieve. The design of the RMI involved establishing a scale of achievement levels or determining the distance between current conditions and an objective threshold or conditions in a reference country, sub-national region, or city. The proposed RMI is constructed by quantifying four public policies, each of which is described by six indicators. The mentioned policies include the identification of risk, risk reduction, disaster management, and governance and financial protection. Risk identification comprises the individual perception, social representation and objective assessment; risk reduction involves the prevention and mitigation; disaster management comprises response and recovery; and, governance and financial protection policy is related to institutionalization and risk transfer. Results at the urban, national and sub-national levels, which illustrate the application of the RMI in those scales, are finally given.  相似文献   

The influence of petrophysical properties on the salt weathering of porous building rocks   总被引：1，自引：0，他引：1  

D. Benavente  N. Cueto  J. Martínez-Martínez  M. A. García del Cura  J. C. Cañaveras 《Environmental Geology》2007,52(2):215-224

The influence of pore structure, water transport properties and rock strength on salt weathering is evaluated by means of a thorough rock characterisation and a statistical analysis. The pore structure was described in terms of its porosity, pore size distribution (quantified by mean pore radius) and specific surface area, density and water transport was characterised by means of water permeability (saturated flow) and capillary imbibition (unsaturated flow); whilst the rock strength test was carried out using uniaxial compressive strength, compressional and shear wave velocities, dynamic elastic constants and waveform energy and attenuation were obtained from the digital analysis of the transmitted signal. A principal component analysis and a stepwise multiple regression model was carried out in order to examine the direct relationships between salt weathering and petrophysical properties. From the principal component analysis, two main components were obtained and assigned a petrophysical meaning. The first component is mostly linked to mechanical properties, porosity and density whereas the second component is associated with the water transport and pore structure. Salt weathering, quantified by the percentage of weight loss after salt crystallisation, was included in both principal components, showing its dependence on their petrophysical properties. The stepwise multiple regression analysis found that rock strength has a predominant statistical weight in the prediction of salt weathering, with a minor contribution of water transport and pore structure parameters.  相似文献   

Spatial variability of soil quality in the surroundings of a saline lake environment     

María Eugenia Pérez González  María del Pilar García Rodríguez  Vanesa González-Quiñones  Raimundo Jiménez Ballesta 《Environmental Geology》2006,51(1):143-149

The spatial variability of the quality of the soil on the shores of a lagoon affected by hydromorphy and/or salinity can be identified (Laguna de Villacañas, Castilla La Mancha) by the use of multitemporal Landsat images in order to analyse these changes. For this purpose, TM and ETM images along with field observations and certain edaphic laboratory parameters are used. In order to identify saline-hydromorphic soils, the spatial variability of chemical and physical properties of a transect, which includes from Solonchaks to Regosols and Cambisols, have been correlated with the Normalised Difference Vegetation Index (NDVI). This index, chosen for specific dates, has proven to be very useful in detecting halophytic vegetation and relating it to the variability of the quality of these soils.  相似文献