Satellite guidance systems in agriculture: experimental comparison between EZ-Steer/RTK and AUTOPILOT/EGNOS

The research has been conducted using two different satellite-guidance devices and two different correction systems of the GPS signal: the EZ-Steer/RTK and Autopilot/EGNOS. The machines used in the tests were the tractor New Holland T7060, the rotary harrow Alpego DG-400 and the burier Forigo DG-45, in order to determine which of the two systems ensured the best quality of work. On the basis of the results obtained it is clear that the EZ-Steer/RTK system, guarantees a lower stability of the theoretical trajectory compared to the Autopilot/EGNOS system, above 1,77%. From the elaboration of data of the two guidance systems behavior to manage the only width of transposition, it is observed that the EZ-Steer/RTK system is able to guarantee a better hold of the line compared to the Autopilot/EGNOS system, which provides a mistake of 164 cm on the total width of transposition and 2 cm on the mean value. In the matter of the normalized transposition surfaces, the Autopilot/EGNOS system ensures a better work quality

Numerical modelling of gas-water-rock interactions in volcanic-hydrothermal environment: the Ischia Island (Southern Italy) case study.

Hydrothermal systems hosted within active volcanic systems represent an excellent opportunity to investigate the interactions between aquifer rocks, infiltrating waters and deep-rising magmatic fluids, and thus allow deriving information on the activity state of dormant volcanoes. From a thermodynamic perspective, gas-water-rock interaction processes are normally far from equilibrium, but can be represented by an array of chemical reactions, in which irreversible mass transfer occurs from host rock minerals to leaching solutions, and then to secondary hydrothermal minerals. While initially developed to investigate interactions in near-surface groundwater environments, the reaction path modeling approach of Helgeson and co-workers can also be applied to quantitative investigation of reactions in high T-P environments. Ischia volcano, being the site of diffuse hydrothermal circulation, is an ideal place where to test the application of reaction-path modeling. Since its last eruption in 1302 AD, Ischia has shown a variety of hydrothermal features, including fumarolic emissions, diffuse soil degassing and hot waters discharges. These are the superficial manifestation of an intense hydrothermal circulation at depth. A recent work has shown the existence of several superposed aquifers; the shallowest (near to boiling) feeds the numerous surface thermal discharges, and is recharged by both superficial waters and deeper and hotter (150-260° C) hydrothermal reservoir fluids. Here, we use reaction path modelling (performed by using the code EQ3/6) to quantitatively constrain the compositional evolution of Ischia thermal fluids during their hydrothermal flow. Simulations suggest that compositions of Ischia groundwaters are buffered by interactions between reservoir rocks and recharge waters (meteoric fluids variably mixed - from 2 to 80% - with seawater) at shallow aquifer conditions. A CO2 rich gaseous phase is also involved in the interaction processes (fCO2 = 0.4-0.6 bar). Overall, our model calculations satisfactorily reproduce the main chemical features of Ischia groundwaters. In the model runs, attainment of partial to complete equilibrium with albite and K-feldspar fixes the Na/K ratios of the model solutions at values closely matching those of natural samples. Precipitation of secondary phases, mainly clay minerals (smectite and saponite) and zeolites (clinoptilolite), during the reaction path is able to well explain the large Mg-depletions which characterise Ischia thermal groundwaters; while pyrite and troilite are shown to control sulphur abundance in aqueous solutions. SiO2(aq) contents in model simulations fit those measured in groundwaters and are being buffered by the formation of quartz polymorphs and Si-bearing minerals. Finally, our simulations are able to reproduce redox conditions and Fe-depletion trends of natural samples. We conclude that reaction path modelling is an useful tool for quantitative exploration of chemical process within volcano-hosted hydrothermal systems

Slab disruption, mantle circulation, and the opening of the Tyrrhenian basins

Plate tectonic history, geological, geochemical (element and isotope ratios), and seismological (P-wave tomography and SKS splitting) data are combined with laboratory modeling to present a three-dimensional reconstruction of the subduction history of the central Mediterranean subduction. We fi nd that the dynamic evolution of the Calabrian slab is characterized by a strong episodicity revealed also by the discrete opening of the Tyrrhenian Sea. The Calabrian slab has been progressively disrupted by means of mechanical and thermal erosion leading to the formation of large windows, both in the southern Tyrrhenian Sea and in the southern Apennines. Windows at lateral slab edges have caused a dramatic reorganization of mantle convection, permitting infl ow of subslab mantle material and causing a complicated pattern of magmatism in the Tyrrhenian region, with coexisting K- and Na-alkaline igneous rocks. Rapid, intermittent avalanches of large amounts of lithospheric material at slab edges progressively reduced the lateral length of the Calabrian slab to a narrow (200 km) slab plunging down into the mantle and enhancing the end of the subduction process

Data trustworthiness and user reputation as indicators of VGI quality

ABSTRACTVolunteered geographic information (VGI) has entered a phase where there are both a substantial amount of crowdsourced information available and a big interest in using it by organizations. But the issue of deciding the quality of VGI without resorting to a comparison with authoritative data remains an open challenge. This article first formulates the problem of quality assessment of VGI data. Then presents a model to measure trustworthiness of information and reputation of contributors by analyzing geometric, qualitative, and semantic aspects of edits over time. An implementation of the model is running on a small data-set for a preliminary empirical validation. The results indicate that the computed trustworthiness provides a valid approximation of VGI quality

Structural and Spectroscopic Behavior of double Metal Oxalates from the first transition Metal Series

A series of double metal oxalates of stoichiometry MM´(C2O4)2.4H2O (with MM´= MnCo, MnNi, MnZn, CoNi, CoCu, CoZn, NiCu, NiZn and CuZn have been prepared and characterized. Their structural behavior was investigated by means of X-ray powder diffractometry, showing a strong structural analogy to the orthorhombic, so-called beta-modification, of the related simple oxalato complexes of composition MC2O4.2H2O. The vibrational spectroscopic behavior of the double metal oxalates was investigated by infrared and Raman spectroscopy. The results clearly confirmed the close structural analogies between the MM´(C2O4)2.4H2O, alfa-MC2O4.2H2O and beta-MC2O4.2H2O series of complexes.Fil: D’Antonio, María C.. Universidad Nacional de la Patagonia Austral. Unidad Académica Río Gallegos; ArgentinaFil: Torres, María Marta. Universidad Nacional de la Patagonia Austral. Unidad Académica Río Gallegos; ArgentinaFil: Palacios, Daniel Alejandro. Universidad Nacional de la Patagonia Austral. Unidad Académica Río Gallegos; ArgentinaFil: Gonzalez Baro, Ana Cecilia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Química Inorgánica "Dr. Pedro J. Aymonino". Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Centro de Química Inorgánica "Dr. Pedro J. Aymonino"; ArgentinaFil: Barone, Vicente Luis. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Química Inorgánica "Dr. Pedro J. Aymonino". Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Centro de Química Inorgánica "Dr. Pedro J. Aymonino"; ArgentinaFil: Baran, Enrique José. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Química Inorgánica "Dr. Pedro J. Aymonino". Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Centro de Química Inorgánica "Dr. Pedro J. Aymonino"; Argentin

Increasing the bandwidth of resonant gravitational antennas: The case of Explorer

Resonant gravitational wave detectors with an observation bandwidth of tens of hertz are a reality: the antenna Explorer, operated at CERN by the ROG collaboration, has been upgraded with a new read-out. In this new configuration, it exhibits an unprecedented useful bandwidth: in over 55 Hz about its frequency of operation of 919 Hz the spectral sensitivity is better than 10^{-20} /sqrt(Hz) . We describe the detector and its sensitivity and discuss the foreseable upgrades to even larger bandwidths.Comment: 4 pages- 4 figures Acceted for publication on Physical Review Letter

Particle acoustic detection in gravitational wave aluminum resonant antennas

The results on cosmic rays detected by the gravitational antenna NAUTILUS have motivated an experiment (RAP) based on a suspended cylindrical bar, which is made of the same aluminum alloy as NAUTILUS and is exposed to a high energy electron beam. Mechanical vibrations originate from the local thermal expansion caused by warming up due to the energy lost by particles crossing the material. The aim of the experiment is to measure the amplitude of the fundamental longitudinal vibration at different temperatures. We report on the results obtained down to a temperature of about 4 K, which agree at the level of about 10% with the predictions of the model describing the underlying physical process.Comment: RAP experiment, 16 pages, 7 figure

Search for Periodic Gravitational Wave Sources with the Explorer Detector

We have developped a procedure for the search of periodic signals in the data of gravitational wave detectors. We report here the analysis of one year of data from the resonant detector Explorer, searching for pulsars located in the Galactic Center (GC). No signals with amplitude greater than $\bar{h}= 2.9~10^{-24}$, in the range 921.32-921.38 Hz, were observed using data collected over a time period of 95.7 days, for a source located at $\alpha=17.70 \pm 0.01$ hours and $\delta=-29.00 \pm 0.05$ degrees. Our procedure can be extended for any assumed position in the sky and for a more general all-sky search, even with a frequency correction at the source due to the spin-down and Doppler effects.Comment: One zipped file (Latex+eps figures). 33 pages, 14 figures. This and related material also at http://grwav3.roma1.infn.it