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321.
Pietro Bolli Luca Cresci Frederick Huang Sergio Mariotti Dario Panella 《Experimental Astronomy》2018,45(2):165-176
A High Temperature Superconductor filter operating in the C-band between 4200 and 5600 MHz has been developed for one of the radio astronomical receivers of the Sardinia Radio Telescope. The motivation was to attenuate an interference from a weather radar at 5640 MHz, whose power level exceeds the linear region of the first active stages of the receiver. A very sharp transition after the nominal maximum passband frequency is reached by combining a 6th order band-pass filter with a 6th order stop-band. This solution is competitive with an alternative layout based on a cascaded triplet filter. Three units of the filter have been measured with two different calibration approaches to investigate pros and cons of each, and data repeatability. The final performance figures of the filters are: ohmic losses of the order of 0.15–0.25 dB, matching better than ?15 dB, and ?30 dB attenuation at 5640 MHz. Finally, a more accurate model of the connection between external connector and microstrip shows a better agreement between simulations and experimental data. 相似文献
322.
323.
Show me the code: spatial analysis and open source 总被引:3,自引:1,他引:2
Sergio J. Rey 《Journal of Geographical Systems》2009,11(2):191-207
This paper considers the intersection of academic spatial analysis with the open source revolution. Its basic premise is that
the potential for cross-fertilization between the two is rich, yet some misperceptions about these two communities pose challenges
to realizing these opportunities. The paper provides a primer on the open source movement for academicians with an eye towards
correcting these misperceptions. It identifies a number of ways in which increased adoption of open source practices in spatial
analysis can enhance the development of the next generation of tools and the wider practice of scientific research and education.
相似文献
Sergio J. ReyEmail: |
324.
Caterina Panzeca Aaron J. Beck Antonio Tovar-Sanchez Jose Segovia-Zavala Gordon T. Taylor Christopher J. Gobler Sergio A. Saudo-Wilhelmy 《Estuarine, Coastal and Shelf Science》2009,85(2):223-230
Distributions of dissolved vitamin B12 and total dissolved Co were measured to gain an understanding of the cycling of these interdependent micronutrients in six marine settings including; an upwelling location, a semi-enclosed bay, two urban coastal systems, and two open ocean locations. Along the coast of Baja California, Mexico, concentrations of B12 and dissolved Co varied from 0.2 to 11 pM and 180 to 990 pM, respectively. At a nearby upwelling station, vitamin B12 and Co concentrations ranged from 0.3 to 7.0 pM and 22 to 145 pM, and concentrations did not correlate with upwelling intensity. Concentrations of B12 were highest within Todos Santos Bay, a semi-enclosed bay off the coast of Baja California, Mexico, during a dinoflagellate bloom, ranging from 2 to 61 pM, while Co concentrations varied between 61 and 194 pM. In the anthropogenically impacted Long Island Sound, NY, U.S.A., B12 levels were between 0.1 and 23 pM and Co concentrations varied from 60 to 1900 pM. However, anthropogenic inputs were not evident in B12 levels in the San Pedro Basin, located outside Los Angeles, Ca, U.S.A., where concentrations of B12 were 0.2–1.8 pM, approximating observed open ocean B12 concentrations. In the Southern Ocean and North Atlantic Ocean, B12 levels were 0.4–4 pM and 0.2–2 pM, respectively. Total Co concentrations in the Southern Ocean and North Atlantic tended to be low; measuring 26–59 pM and 15–80 pM, respectively. These low Co concentrations may limit B12 synthesis and its availability to B12-requiring phytoplankton because the total dissolved Co pool is not necessarily entirely bioavailable. 相似文献
325.
Stefano Covelli Alessandro Acquavita Raffaella Piani Sergio Predonzani Cinzia De Vittor 《Estuarine, Coastal and Shelf Science》2009
The Marano Lagoon, in the northern Adriatic Sea (Italy), has been affected by mercury (Hg) contamination from industrial and mining activities. It has been estimated that 186,000 kg of Hg were deliberately discharged into the main drainage system (Aussa–Corno River) by a chlor-alkali plant (CAP) from 1940s to 1984. The lagoon has also experienced a secondary long-term Hg input, originated from mining activity in Idrija (Slovenia), due to the supply of fluvial suspended particles carried by the Isonzo River in the Gulf of Trieste. Since local fishing activities are extensively conducted, there is great concern on the risk posed by potentially harmful effects of Hg to the trophic chain. 相似文献
326.
Sergio M. López-Ramírez Leonardo Sáenz Alex Mayer Lyssette E. Muñoz-Villers Heidi Asbjornsen Z. Carter Berry Nathaniel Looker Robert Manson León Rodrigo Gómez-Aguilar 《水文研究》2020,34(16):3555-3570
Tropical montane cloud forests (TMCF) are recognized for their capacity to maintain high dry-season baseflow and a host of other ecosystem services. Substantial areas of TMCF have been converted to pasture and crops such as coffee, while in other areas TCMF are recovering. However, little is known about the effects of this complex dynamic on catchment hydrology. We investigated the effect of land use on rainfall-runoff response in five neighbouring headwater micro-catchments in central Veracruz, Mexico, dominated by either mature TMCF (MF), young (20 year-old) and intermediate (40 year-old) naturally regenerating TMCF (YF and IF, respectively), shaded coffee (SC), and an intensively grazed pasture (IP). We used a 4-year record of high-resolution rainfall and streamflow (10 min) data collected from 2015 to 2019. These data were analysed via comparison of hydrologic metrics that summarize streamflow responses at various time scales and magnitudes. Results showed no statistical difference in the regulation capacity of high flows in the micro-catchment with 20 years of natural regeneration, compared to the MF. In terms of baseflow sustenance, our results support the hypothesis that MF and IF better promote this hydrologic service than the other land uses. SC exhibited a high capacity to modulate peak flows comparable to that of MF, and an intermediate capacity to sustain baseflow, suggesting that the integrated functioning of this micro-catchment was largely preserved. Finally, 40 years of intense pasture management was found to have degraded the soil hydraulic properties of IP; mainly, reducing its infiltration capacity, causing a fivefold greater peak flow response and a lower baseflow compared to MF. 相似文献
327.
Anna M. Nobili Gian Luca Comandi Suresh Doravari Donato Bramanti Rajeev Kumar Francesco Maccarrone Erseo Polacco Slava G. Turyshev Michael Shao John Lipa Hansjoerg Dittus Claus Laemmerzhal Achim Peters Jurgen Mueller C. S. Unnikrishnan Ian W. Roxburgh Alain Brillet Christian Marchal Jun Luo Jozef van der Ha Vadim Milyukov Valerio Iafolla David Lucchesi Paolo Tortora Paolo De Bernardis Federico Palmonari Sergio Focardi Dino Zanello Salvatore Monaco Giovanni Mengali Luciano Anselmo Lorenzo Iorio Zoran Knezevic 《Experimental Astronomy》2009,23(2):689-710
“Galileo Galilei” (GG) is a small satellite designed to fly in low Earth orbit with the goal of testing the Equivalence Principle—which
is at the basis of the General Theory of Relativity—to 1 part in 1017. If successful, it would improve current laboratory results by 4 orders of magnitude. A confirmation would strongly constrain
theories; proof of violation is believed to lead to a scientific revolution. The experiment design allows it to be carried
out at ambient temperature inside a small 1-axis stabilized satellite (250 kg total mass). GG is under investigation at Phase
A-2 level by ASI (Agenzia Spaziale Italiana) at Thales Alenia Space in Torino, while a laboratory prototype (known as GGG)
is operational at INFN laboratories in Pisa, supported by INFN (Istituto Nazionale di fisica Nucleare) and ASI. A final study
report will be published in 2009. 相似文献
328.
Angelo Camerlenghi Daniela Accettella Sergio Costa Galderic Lastras Juan Acosta Miquel Canals Nigel Wardell 《International Journal of Earth Sciences》2009,98(4):735-750
We present the seafloor morphology and shallow seismic structure of the continental slope south-east of the Balearic promontory
and of the adjacent Algero-Balearic abyssal plain from multibeam and chirp sonar data. The main purpose of this research was
to identify the sediment pathways from the Balearic promontory to the Algero-Balearic deep basin from the Early Pliocene to
the Present. The morphology of the southern Balearic margin is controlled by a SW–NE structural trend, whose main expressions
are the Emile Baudot Escarpment transform fault, and a newly discovered WSW–ENE trend that affects the SW end of the escarpment
and the abyssal plain. We relate the two structural trends to right-lateral simple shear as a consequence of the Miocene westward
migration of the Gibraltar Arc. Newly discovered steep and narrow volcanic ridges were probably enabled to grow by local transtension
along the transform margin. Abyssal plain knolls and seahills relate to the subsurface deformation of early stage halokinetic
structures such as salt rollers, salt anticlines, and salt pillows. The limited thickness of the overburden and the limited
amount of deformation in the deep basin prevent the formation of more mature halokinetic structures such as diapirs, salt
walls, bulbs, and salt extrusions. The uppermost sediment cover is affected by a dense pattern of sub-vertical small throw
normal faults resulting from extensional stress induced in the overburden by subsurface salt deformation structures. Shallow
gas seismic character and the possible presence of an active polygonal fault system suggest upward fluid migration and fluid
and sediment expulsion at the seafloor through a probable mud volcano and other piercement structures. One large debris flow
deposit, named Formentera Debris Flow, has been identified on the lower slope and rise of the south Formentera margin. Based
on current observations, we hypothesize that the landslide originating the Formentera Debris Flow occurred in the Holocene,
perhaps in historical times.
相似文献
Angelo CamerlenghiEmail: |
329.
Sergio Martos-Rosillo Miguel Rodríguez-Rodríguez Francisco Moral José Javier Cruz-Sanjulián Juan Carlos Rubio 《Hydrogeology Journal》2009,17(7):1617-1627
The carbonate aquifers of Lora and Mingo form part of the hydrogeological unit of Sierra de Estepa (SE Spain). By means of time series analysis and a 1D numerical groundwater model, groundwater exploitation was quantified and the mean annual recharge in both systems was estimated (2001–2004). During this period, the Lora and Mingo aquifers received an average groundwater recharge of 0.29 × 106 m3/year and 0.14 × 106 m3/year, respectively, whereas an average of 0.34 × 106 m3/year and 0.21 × 106 m3/year, respectively, was extracted. These conditions led to a conspicuous lowering of the water table in both systems. In addition, the analysis of the evolution of the main hydrogeochemical parameters of the groundwater showed that the increased pumping rates produced an increase in total dissolved solids, and chloride and sodium ions in both aquifers. In the case of the Lora aquifer, the only ion that presented decreased levels was nitrate. The results show that groundwater pumping in both aquifers should not exceed the mean annual recharge of 0.29 × 106 m3/year and 0.14 × 106 m3/year in the Lora and Mingo aquifers, respectively. Nevertheless, it would be advisable to reduce pumping rates to below these values in order to restore piezometric levels and improve groundwater quality for different uses in the future. 相似文献
330.
In the present work, a new simplified model approach for sediment delivery ratio (SDR) assessment is proposed. Modelling and
assessing SDR is still an open question. Difficulties rise from the lack of sufficient data availability, on one side, and,
on the other, from the inherent uncertainties including spatial variability and temporal discontinuity of the land cover,
climatic, hydrological and geomorphological variables involved. The proposed SDRSIM model tries to skip over the limitations observed in other models generally adopted. A comparison with two different selected
models amongst the most widespread simplified models, i.e. the area-model and the slope-model, is showed in application to
a wide range of catchments extensions across different landscapes of Italy. The SDRSIM estimates were also evaluated against observed SDR over a validation dataset of 11 basins sparse over different regions of
the world. The results showed the effectiveness of the proposed model approach based on easily available catchment parameters. 相似文献