Literature review of accessibility measures and models used in land use and transportation planning in last 5 years     

Marwal  Aviral  Silva  Elisabete 《地理学报(英文版)》2022,32(3):560-584

Journal of Geographical Sciences - Since its inception accessibility has undergone various changes in the way it is defined, measured, and modeled. The paper reviews the recent advancements made in...  相似文献   

Center-to-Limb Variation of Solar Microwave Bursts     

Silva  Adriana V.R.  Valente  Marcelo M. 《Solar physics》2002,206(1):177-188

Statistical studies of hard X-ray flares position on the solar disk have shown that the more energetic hard X-rays have a tendency to be more concentrated near the limb rather than at disk center, whereas lower-energy hard X-ray emission seems isotropic. Since the high-frequency radio emission is believed to be produced by the same energetic electron population responsible for the high-energy hard X-rays, we searched the microwave/millimeter emitting bursts for center-to-limb variation in their emission. A total of 499 bursts observed by the radio telescopes in Bern at the frequencies of 3.1, 5.2, 8.4, 11.8, 19.6, 35.0, and 50.0 GHz were analyzed. Simultaneous Hα flares were used for determination of the radio burst position on the solar disk. For each of the 7 frequencies, the peak flux and duration were studied as a function of heliocentric position. For 312 bursts, spectral parameters such as spectral index, peak frequency, and flux at spectral maximum were analyzed. For a subset of 43 bursts with emission at all frequencies, the emission and spectral parameters were analyzed. Center-to-limb variations of the spectral parameters for all bursts were sought. In order to interpret the observational results, we have performed a numerical simulation of gyrosynchrotron spectra. We find that high-frequency events, which are also the more energetic ones, have larger center-to-limb variations in their parameters than do the overall flares. Moreover, this behavior agrees with theoretical predictions.  相似文献   

Old stellar populations in NGC 5128     

M. Rejkuba  D. Minniti  D. Silva  T. Bedding 《Astrophysics and Space Science》2002,281(1-2):425-426

We have resolved the stars in the halo and in the diffuse northeastern shell of the nearest giant elliptical galaxy NGC 5128 using VLT with FORS1 and ISAAC. Dominating feature in the optical-near IR color-magnitude diagrams is abroad red giant branch, indicating a large spread in metallicity of the stars. We have detected a significant number of sources brighter than the tip of the red giant branch. The variability monitoring of these bright red giants shows that they are long period variables similar to Miras. This revised version was published online in September 2006 with corrections to the Cover Date.  相似文献   

Acknowledgment of referees     

Antonio C. da Silva  Scott T. Kay  rew R. Liddle  Peter A. Thomas 《Monthly notices of the Royal Astronomical Society》2004,355(4):1401-1408

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Temporal variability of selected dissolved elements in the lower Orinoco River,Venezuela     

Abrahan Mora  Juan A. Alfonso  Luzmila Sánchez  Malvis Calzadilla  Soraya Silva  John J. LaBrecque  José A. Azócar 《水文研究》2009,23(3):476-485

Monthly analyses of pH, conductance, alkalinity, total suspended solids, dissolved major cations (Na, K, Ca and Mg), and selected dissolved trace elements (Fe, Al, Mn, Cu, Zn and Cr) were conducted on waters of the lower Orinoco River from February 2004 to May 2006. The data show strong seasonal variability. Major cations had maximum concentrations at low water, and were correlated with pH, conductance and alkalinity because of the tributaries coming from the Andean zones, where the weathering of evaporites and carbonate shales controls water chemistry. K concentrations did not show any relation with evaporite weathering, probably because large amounts of K come from the Guayana Shield rivers as a consequence of feldspar weathering. The concentrations of dissolved Fe, Mn and Cu were highest during the high water stage. Concentrations of the elements K, Cr, Zn and Cu are correlated with each other but not with dissolved Fe and Al, which probably are complexed with humic and fulvic substances. Mn concentrations did not show relationships with other variables. Inter‐annual variability of dissolved elements is explained by temporal changes in precipitation. Copyright © 2008 John Wiley & Sons, Ltd.  相似文献   

Assessment of WRF numerical model forecasts using different lead time initializations during extreme precipitation events over Macaé city,Rio de Janeiro (Brazil)     

da Silva  Fabricio Polifke  da Silva  Alfredo Silveira  da Silva  Maria Gertrudes Alvarez Justi  Pires  Gisele Dornelles 《Natural Hazards》2022,110(1):695-718

Natural Hazards - The ability to forecast extreme precipitation events has become increasingly important over the last decades due to their significant impacts on society and properties. In this...  相似文献   

Construction of Structural Geological Model Using Monte Carlo Simulation     

Xavier  Bruna Catarino  Egydio-Silva  Marcos  Sadowski  Georg Robert  de Assis Silva  Bruno  Takara  Victor Junji 《Geotechnical and Geological Engineering》2022,40(3):1345-1361

Geotechnical and Geological Engineering - To optimize the prediction of structural geological conditions in the underground as of data collected at the surface, due to the usual great uncertainties...  相似文献   

The Mineral Adsorption and The Application of a Metamorphic Felsic Rock as Aggregate in Asphalt Pavements     

Lago  Larissa Neves  Casagrande  Michéle Dal Toé  da Conceição Ribeiro  Roberto Carlos  de Albuquerque e Silva  Ben-Hur 《Geotechnical and Geological Engineering》2022,40(3):1585-1595

Geotechnical and Geological Engineering - The aggregates consist approximately 85% of the total volume in asphalts pavements, and their properties influence directly their behavior. Therefore, it...  相似文献   

Seismic risk assessment and hazard mapping in Nepal     

Chaulagain  Hemchandra  Rodrigues  Hugo  Silva  Vitor  Spacone  Enrico  Varum  Humberto 《Natural Hazards》2015,78(1):583-602

Natural Hazards - Seismic risk in the form of impending disaster has been seen from past records that moderate-to-large earthquakes have caused the loss of life and property in all parts of Nepal....  相似文献   

Revisiting wintertime cold air intrusions at the east of the Andes: propagating features from subtropical Argentina to Peruvian Amazon and relationship with large-scale circulation patterns     

Jhan Carlo Espinoza  Josyane Ronchail  Matthieu Lengaigne  Nelson Quispe  Yamina Silva  Maria Laura Bettolli  Grinia Avalos  Alan Llacza 《Climate Dynamics》2013,41(7-8):1983-2002

This study investigates the spatial and temporal characteristics of cold surges that propagates northward along the eastern flank of the Andes from subtropical to tropical South America analysing wintertime in situ daily minimum temperature observations from Argentina, Bolivia and Peru and ERA-40 reanalysis over the 1975–2001 period. Cold surges usually last 2 or 3 days but are generally less persistent in the southern La Plata basin compared to tropical regions. On average, three to four cold surges are reported each year. Our analysis reveals that 52 % of cold episodes registered in the south of La Plata basin propagate northward to the northern Peruvian Amazon at a speed of around 20 m s^?1. In comparison to cold surges that do not reach the tropical region, we demonstrate that these cold surges are characterized, before they reach the tropical region, by a higher occurrence of a specific circulation pattern associated to southern low-level winds progression toward low latitudes combined with subsidence and dry condition in the middle and low troposphere that reinforce the cold episode through a radiative effect. Finally, the relationship between cold surges and atmosphere dynamics is illustrated for the two most severe cold intrusions that reached the Peruvian and Bolivian Amazon in the last 20 years.  相似文献