Preface     

Enrique Pérez  Richard de Grijs  Rosa M. González Delgado 《Astrophysics and Space Science》2009,324(2-4):79-81

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Rebuttal to “Comment on “Evidence of electrical activity on Titan drawn from the Schumann resonances sent by Huygens probe” by J.A. Morente, J.A. Portí, A. Salinas, and E.A. Navarro [2008, Icarus, 195, 802-811]”     

Juan A. Morente  Jorge A. Portí  Enrique A. Navarro 《Icarus》2009,204(1):352-354

Hamelin et al. criticize some conclusions of our paper [Morente, J.A., Portí, J.A., Salinas, A., Navarro, E.A., 2008. Icarus 195, 802-811]. This rebuttal is our response to their criticism. In our view, their comments are contradictory and not based on scientific argument. Our paper presents a comprehensible methodology for extracting weak resonances from the late-time response of systems with high losses and our conclusions are derived from and supported by this methodology, which was first checked using an analytical function and later with the data from a numerical simulation of Titan’s atmosphere. Conversely, the Comment of Hamelin et al. does not contain any mathematical proof, either supporting their statements or invalidating our analysis procedure.  相似文献   

An array of lens-coupled antennas for cosmic microwave background measurements in the 30 Ghz band     

Angel Colin  David Ortiz  Enrique Villa  Edurado Artal  Enrique Martínez-González 《Experimental Astronomy》2012,33(1):27-37

An array of bow-tie slot antennas coupled through an extended hemispherical lens is proposed to operate in the 30?GHz frequency band. The design includes a combination of three microstrip Wilkinson power dividers (WPD) and transitions to coplanar wave guides (CPW) to form the feeding antenna network. This configuration is suitable for the integration with heterodyne imaging detectors commonly used in radioastronomy. Measurements and simulation results exhibit a frequency range of operation from 20 to 40?GHz with a bandwidth of 24% achieved for ?10?dB return loss at the central frequency. The measured radiation patterns show a maximum peak gain of around 13?dB with HPBW of 10° for the E-plane, and whose first side lobes are lower than 13?dB below the main lobe in both angular shift sides. The presented results will be considered as preliminary feasibility studies in the 30?GHz QUIJOTE-CMB Instrument, which is designed to study the anisotropies of the Cosmic Microwave Background (CMB).  相似文献   

In situ measurements of wind‐driven salt fluxes through constructed channels in a coastal wetland ecosystem          下载免费PDF全文

Alex K. Manda  Enrique Reyes  James M. Pitt 《水文研究》2018,32(5):636-643

A suite of instruments was deployed in a coastal wetland ecosystem in the Albemarle estuarine system, North Carolina (USA), to characterize wind‐driven transport of saltwater through a constructed (man‐made) channel. Flow velocity, electrical conductivity, and stage were measured in a representative channel over a 2‐month period from May to July 2014, during which 4 wind tides were observed. Collected data show that thousands of metric tons of salt were advected through the channel into coastal wetlands during each event, which lasted up to 4 days. The results reveal that as much as 36% of advected salts accumulated in the wetlands, suggesting that the cumulative effects of these events on the health of coastal wetlands in the Albemarle system may be substantial due to the abundance of constructed channels and the frequency of wind‐driven tidal events. This study is the first to quantify wind‐driven salt fluxes through constructed channels in coastal wetland settings.  相似文献   

Spatial patterns and driving mechanisms of mid‐Holocene hydroclimate in western North America          下载免费PDF全文

Nicholas Wayne Hermann  Jessica Leigh Oster  Daniel Enrique Ibarra 《第四纪科学杂志》2018,33(4):421-434

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Late Pleistocene climate of the northern Iberian Peninsula: New insights from palaeoglaciers at Fuentes Carrionas (Cantabrian Mountains)     

Ramn Pellitero  Jos M. Fernndez‐Fernndez  Nstor Campos  Enrique Serrano  Alfonso Pisabarro 《第四纪科学杂志》2019,34(4-5):342-354

New ¹⁰Be dates for glacial landforms in the Fuentes Carrionas area (Cantabrian Mountains, nothern Spain) are presented. Mapped and dated landforms in Fuentes Carrionas made possible a palaeoglacier reconstruction for four glacial stages. Results were compared to other nearby palaeoenvironmental proxies, so a final approximation on the mean annual temperature and annual precipitation that caused the four glacial advance stages is proposed. Glaciers reached their maximum extension at 36 ka, in a cold and dry environment. A second advance stage took place between 18.5 and 19.5 ka, during the Last Glacial Maximum (LGM), when glaciers advanced in a wet environment, with positive rainfall anomalies. A third glacial advance was dated during the Oldest Dryas, in which climate shifted to extremely cold and dry conditions. Finally, a last stage has been identified and proposed to the Younger Dryas, in which precipitation anomalies are negligible. Our results confirm some of the previously made palaeoglacial and palaeoenvironmental inferences for the Iberian Peninsula, as well as provide valuable and accurate anomalies, which are useful for climate modelling.  相似文献   

Geostatistical Algorithm Selection for Mineral Resources Assessment and its Impact on Open-pit Production Planning Considering Metal Grade Boundary Effect     

Maleki  Mohammad  Madani  Nasser  Jélvez  Enrique 《Natural Resources Research》2021,30(6):4079-4094

Mine planning is influenced by many sources of uncertainty. Significant sources of geological uncertainty in mine planning include uncertainty in layout of geological domains and uncertainty in metal grades. These two sources of uncertainty cannot be modeled separately because the distribution of the grade is controlled usually by geological domains. Two approaches exist for combining these two sources of uncertainty: the joint simulation approach and the cascade approach. In this paper, these two approaches were compared using a real case study. To this end, uncertainty in iron grade (quantitative variable) and ore zones (qualitative variable) was modeled using both approaches. There were some considerable differences in the results obtained by each approach, which confirm the importance of choosing the most appropriate approach with consideration of the dominate features of a deposit.

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Predictions for the clustering properties of the Lyman-alpha forest – I. One-point statistics     

Enrique Gaztañaga  Rupert A. C. Croft 《Monthly notices of the Royal Astronomical Society》1999,309(4):885-904

We present predictions for the one-point probability distribution and cumulants of the transmitted QSO flux in the high redshift Lyman- α forest. We make use of the correlation between the Lyman- α optical depth and the underlying matter density predicted by gravitational instability theory and seen in numerical hydrodynamic simulations. We have modelled the growth of matter fluctuations using the non-linear shear‐free dynamics, an approximation which reproduces well the results of perturbation theory for the cumulants in the linear and weakly non-linear clustering regime. As high matter overdensities tend to saturate in spectra, the statistics of the flux distribution are dominated by weakly non-linear overdensities. As a result, our analytic approach can produce accurate predictions, when tested against N -body simulation results, even when the underlying matter field has root-mean-square fluctuations larger than unity. Our treatment can be applied to either Gaussian or non-Gaussian initial conditions. Here we concentrate on the former case, but also include a study of a specific non-Gaussian model. We discuss how the methods and predictions we present can be used as a tool to study the generic clustering properties of the Lyman- α forest at high redshift. With such an approach, rather than concentrating on simulating specific cosmological models, we may be in a position to directly test our assumptions for the Gaussian nature of the initial conditions, and the gravitational instability origin of structure itself. In a separate paper we present results for two-point statistics.  相似文献   

The scope for generating bio-oils with relatively low oxygen contents via hydropyrolysis   总被引：3，自引：0，他引：3  

J. Dilcio Rocha  Carlos A. Luengo  Colin E. Snape   《Organic Geochemistry》1999,30(12):1599

The primary oils obtained in high yields from fast (fluidised-bed) pyrolysis of biomass generally have high oxygen contents (ca. 40% w/w). The scope for using pyrolysis under hydrogen pressure (hydropyrolysis), to give oils with much lower oxygen contents compared to normal pyrolysis has been investigated. Fixed-bed hydropyrolysis tests have been conducted on cellulose, sugar cane bagasse and eucalyptus wood using hydrogen pressures up to 10 MPa, with heating rates of 5 and 300°C min⁻¹. A colloidal FeS catalyst was used in some tests (Fe loading of 5%, w/w) to increase overall conversions. Further, the attractive option of using a two-stage reactor in which the primary oil vapors are passed though a bed of hydrotreating catalyst is also described. Raising the hydrogen pressure from atmospheric to 10 MPa reduced the oxygen content of the primary oil by over 10% to below 20% w/w. The addition of a dispersed iron sulphide catalyst gave conversions close to 100% for all three biomass samples investigated at 10 MPa under conditions in the fixed-bed reactor where significant diffusional resistances existed and reduced the oxygen content of the bio-oil by a further 10%. Although NMR indicated that the oils became increasingly aromatic as more oxygen was removed, the increase in hydrogen pressure decreased the extent of overall aromatisation that occurs primarily due to the lower char yields obtained. In two-stage tests for cellulose, using a commercial sulphided Ni/Mo γ-Al₂O₃ catalyst at 400°C, increasing the hydrogen pressure from 2.5 to 10 MPa decreased the oxygen content of the oil by over 20% to 10% w/w. The H/C ratios were higher and O/C ratios smaller for the two-stage bio-oils compared to their single stage counterparts. However, the differences in the O/C ratios between the single and two-stage bio-oils increase with pressure.  相似文献   

On the significance of the climate-dataset time resolution in characterising wind-driven rain and simultaneous wind pressure. Part I: scalar approach     

Pérez-Bella  José M.  Domínguez-Hernández  Javier  Cano-Suñén  Enrique  del Coz-Díaz  Juan J.  Alonso-Martínez  Mar 《Stochastic Environmental Research and Risk Assessment (SERRA)》2018,32(6):1783-1797

Stochastic Environmental Research and Risk Assessment - The joint action of wind-driven rain and wind pressure is the main cause of water penetration in building facades, which causes various...  相似文献