The low-luminosity galaxy population in the NGC 5044 Group     

Sergio A. Cellone  Alberto Buzzoni 《Monthly notices of the Royal Astronomical Society》2005,356(1):41-53

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Earthquake Magnitude Transition Probability and Causal Dependence for Mexico City Earthquakes     

Sergio G. Ferraes 《Geophysical Journal International》1974,38(2):315-316

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Longitudinal variation of equatorial electrojet parameters derived from POGO satellite observations     

C.A. Onwumechili  C.E. Agu 《Planetary and Space Science》1981,29(6):627-634

A method of analysis has been developed making it possible to obtain electrojet parameters from vertical profiles of the POGO electrojet data. This has provided an unprecedented quantity of electrojet parameters—about 500 each of its peak eastward current intensity J₀, its total eastward current I₊, and its half width w—spanning through 360° longitude round the Earth, 5 h of daytime and September equinoctial months of the years 1967, 1968 and 1969. The daytime all-longitude averages of the parameters for the 3 years are 235 ± 14 km for w, 232 ± 63A km^?1 for J₀ and (54 ± 11) × 10³A for I₊. This first coverage round the globe shows that J₀ and I₊ vary considerably with longitude unlike w. While confirming the expected maximum of J₀ and I₊ at about 280°E longitude, we find that each of them also has an unexpected major maximum at about 100°E and a subsidiary maximum at 190°E longitude. The major maxima are found to be prominent only at hours near local noon. It is argued that the surprising longitudinal variations of J₀ and I₊ cannot be explained satisfactorily by variations in the upper mantle conductivity along the dip equator but possibly by longitudinal variations of wind systems and gradients at electrojet altitudes.  相似文献   

The COBE-DMR database and how to use it     

Sergio Torres 《Astrophysics and Space Science》1995,228(1-2):309-312

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The multifunction photoelectric photometer of Torino Observatory     

Sergio Furlani  Giorgio Sedmak 《Astrophysics and Space Science》1977,48(1):65-78

The paper describes the design and the realization of a multiple-function photoelectric photometer made by Trieste Observatory for Torino Observatory. The system design shows a two-beam, sequential multiband photon counting and analog photoelectric photometer configuration based on a PDP8/E computer for the control and data acquisition and elaboration. The actual realization of the system and the use of it in the one-beam configuration operating now at torino Observatory shows the advantages of such a solution and the easiness in modifying and determining the system functions by software programs rather than by hardware specials. Work supported by Consiglio Nazionale delle Ricerche, Gruppo Nazionale di Astronomia, Settore Tecnologie Astronomiche. The realization of the machine was fully supported by Torino Observatory. Trieste Observatory-Instruments and Data Processing Group (5/76).  相似文献   

General features of the magnetic field of the equatorial electrojet measured by the POGO satellites     

C.A. Onwumechili  C.E. Agu   《Planetary and Space Science》1980,28(12):1125-1130

The magnitude of the equatorial electrojet signature, S, is a measure of its magnetic field at the location of the satellite recording the signature. The general features of the large quantity of the magnetic field data of the electrojet observed by the series of POGO satellites from 1967 to 1970 have been studied here. We have compared the position of the axis of the electrojet as indicated by the position of the minimum of the electrojet signature with the position of the dip equator on the Earth's surface, and we find no significant latitudinal shift of the electrojet axis from the dip equator on the Earth. Apart from the expected decrease of the magnetic field of the electrojet with altitude above the electrojet, we have found unexpected cases in which the field increases with altitude. More surprisingly, we have discovered that the magnitude of S oscillates with altitude having maxima at about 460km and 635km and minima at about 580km and 725km, with a mean wavelength of 160 ± 29 km. It is suggested that this could be caused by additional weak current layers flowing above the main electrojet at about 110 km altitude. It is also pointed out that Onwumechili's model based on a single current system of the equatorial electrojet predicts field oscillation with altitude. The model therefore shows that a field oscillating with altitude can also result from a single complicated system of current unaided by additional current layers.  相似文献   

Magnitude of latent heat in thermally loaded clays     

Sergio Samat  Laurent Brochard  Ioannis Stefanou 《国际地质力学数值与分析法杂志》2020,44(14):1926-1957

Temperature changes are known to induce specific couplings in clay, in particular, an anomalously high thermal pressurization in undrained conditions or a thermal compaction in drained conditions, both of which are potential threats for the mechanical stability and sealing capacity of the geomaterials. Thermodynamical analysis of those peculiar thermomechanical couplings points to a potentially important latent energy, which in turn could limit the temperature change upon heating or cooling. The direct measurement of latent energy developed during a laboratory geomechanical test is challenging. Instead, proper identification of thermal hardening in conventional experiments with temperature changes provides an alternative route to estimate latent energy. In this work, existing laboratory thermomechanical tests of clays are analyzed with a rigorous thermodynamic framework to quantify the magnitude of latent energy in thermomechanically loaded clays. A thermodynamically consistent constitutive model for fully saturated clays that combines two key features, (a) the temperature dependence of the blocked energy and (b) the framework of bounding plasticity, is proposed. The performance of the model is validated by reproducing results obtained in laboratory tests for Boom and Opalinus clays. The thermomechanical loads considered to validate the model performance were then used to estimate the percentage of work that remains latent in the clayey material during plastic yielding. We find that the magnitude of latent energy is quite significant, typically a few tens of percent of the total dissipated energy, and increases significantly with temperature. Accordingly, it is expected to play an important role in the thermomechanical response of clays.  相似文献   

Spatially filtered ridge regression (SFRR): A regression framework to understanding impacts of land cover patterns on urban climate          下载免费PDF全文

Chao Fan  Sergio J. Rey  Soe W. Myint 《Transactions in GIS》2017,21(5):862-879

Understanding the impacts of land cover pattern on the heat island effect is essential for sustainable urban development. Conventional model fitting methods have restricted ability to produce accurate estimates of the land cover‐temperature association due to the lack of procedures to address two important issues: spatial dependence in proximal spatial units and high correlations among predictor variables. In this study, we seek to develop an effective framework called spatially filtered ridge regression (SFRR) to estimate the variations in the quantity and distribution of land surface temperature (LST) in response to various land cover patterns. The SFRR effectively integrates spatial autoregressive models and ridge regression, and it achieves reliable parameter estimates with substantially reduced mean square errors. We show this by comparing the performance of the SFRR to other widely adopted models using Monte Carlo simulation followed by an empirical study over central Phoenix. Results highlight the great potential of the SFRR in producing accurate statistical estimates, providing a positive step toward informed and unbiased decision‐making across a wide variety of disciplines. (Code and data to reproduce the results in the case study are available at: https://github.com/cfan13/SFRRTGIS.git .)  相似文献   

SlugIn 1.0: A Free Tool for Automated Slug Test Analysis          下载免费PDF全文

Sergio Martos‐Rosillo  Carolina Guardiola‐Albert  Alberto Padilla Benítez  Joaquín Delgado Pastor  Antonio Azcón González  Juan José Durán Valsero 《Ground water》2018,56(3):362-365

The correct characterization of aquifer parameters is essential for water‐supply and water‐quality investigations. Slug tests are widely used for these purposes. While free software is available to interpret slug tests, some codes are not user‐friendly, or do not include a wide range of methods to interpret the results, or do not include automatic, inverse solutions to the test data. The private sector has also generated several good programs to interpret slug test data, but they are not free of charge. The computer program SlugIn 1.0 is available online for free download, and is demonstrated to aid in the analysis of slug tests to estimate hydraulic parameters. The program provides an easy‐to‐use Graphical User Interface. SlugIn 1.0 incorporates automated parameter estimation and facilitates the visualization of several interpretations of the same test. It incorporates solutions for confined and unconfined aquifers, partially penetrating wells, skin effects, shape factor, anisotropy, high hydraulic conductivity formations and the Mace test for large‐diameter wells. It is available in English and Spanish and can be downloaded from the web site of the Geological Survey of Spain. Two field examples are presented to illustrate how the software operates.  相似文献   

An extreme wave event in eastern Yucatán,Mexico: Evidence of a palaeotsunami event during the Mayan times     

Javier Lario  Chris Spencer  Teresa Bardají  Ángel Marchante  Victor H. Garduño-monroy  Jorge Macias  Sergio Ortega 《Sedimentology》2020,67(3):1481-1504

The Yucatán Peninsula, Mexico, has typically been considered a tectonically stable region with little significant seismic activity. The region though, is one that is regularly affected by hurricanes. A detailed survey of ca 100 km of the eastern Yucatán and Cozumel coast identified the presence of ridges containing individual boulders measuring >1 m in length. The boulder ridges reach 5 m in height and their origin is associated with extreme wave event activity. Previously modelled tsunami waves from known seismically active zones in the region (Muertos Thrust Belt and South Caribbean Deformed Belt) are not of sufficient scale in the area of the Yucatán Peninsula to have produced the boulder ridges recorded in this study. The occurrence of hurricanes in this region is more common, but two of the most destructive (Hurricane Gilbert 1988 and Hurricane Wilma 2005) produced coastal waves too small to have created the ridges recorded here. In this paper, a new tsunami model with a source area located on the Motagua/Swan Island Fault System has been generated that indicates a tsunami event may have caused the extreme wave events that resulted in the deposition of the boulder ridges.  相似文献