6,857 research outputs found

    Early warning system for the prevention and control of unauthorized accesses to air navigation services infrastructures

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    Early warning systems are fundamental instruments for the management of critical situations since they are able to signal in advance any anomaly with respect to ordinary situations. The purpose of this paper is to present an early warning system, based on artificial neural networks, for the prevention and control of unauthorized accesses to the air navigation services infrastructure in Italy

    Riemannian geometry of Hartogs domains

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    Let D_F = \{(z_0, z) \in {\C}^{n} | |z_0|^2 < b, \|z\|^2 < F(|z_0|^2) \} be a strongly pseudoconvex Hartogs domain endowed with the \K metric gFg_F associated to the \K form ωF=i2ˉlog(F(z02)z2)\omega_F = -\frac{i}{2} \partial \bar{\partial} \log (F(|z_0|^2) - \|z\|^2). This paper contains several results on the Riemannian geometry of these domains. In the first one we prove that if DFD_F admits a non special geodesic (see definition below) through the origin whose trace is a straight line then DFD_F is holomorphically isometric to an open subset of the complex hyperbolic space. In the second theorem we prove that all the geodesics through the origin of DFD_F do not self-intersect, we find necessary and sufficient conditions on FF for DFD_F to be geodesically complete and we prove that DFD_F is locally irreducible as a Riemannian manifold. Finally, we compare the Bergman metric gBg_B and the metric gFg_F in a bounded Hartogs domain and we prove that if gBg_B is a multiple of gFg_F, namely gB=λgFg_B=\lambda g_F, for some λR+\lambda\in \R^+, then DFD_F is holomorphically isometric to an open subset of the complex hyperbolic space.Comment: to appear in International Journal of Mathematic

    High Frequency Model of PV Systems for the Evaluation of Ground Currents

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    A high frequency model of a photovoltaic (PV) plant is developed and analysed to investigate the common mode (CM) currents circulating through the ground connections of the plant. The modelling method is based on the measurement of the impedance frequency response of photovoltaic module and on a high frequency representation of the power conversion unit. An overall lumped parameters circuit model is obtained and then implemented in PSpice. The CM leakage currents are evaluated by simulation

    Territorial Capital and the Great Recession: a Nuts-3 Analysis for Central and Southern Italy

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    The analyses on the effects of the actual crisis have been mainly concentrated on a national and international dimension, leaving aside the differential effects of the crisis on regions and sub-regional areas. Notwithstanding the international character of the Great Recession, it has to be stressed that the different structural features of regions and urban areas might influence the economic and social impact of the crisis. They also might have an important effect on the resilience and recover chance. In the present paper, we focus on territorial capital, a concept that takes into account of the different features of goods and services in terms of their degree of appropriability and rivalry and, also, of their material-immaterial content. The aim is to identify the strategic territorial elements which help in the evaluation of the absorption capacity of the recession at regional and sub-regional levels. For that purpose, we use a wide dataset for Central and Southern Italian provinces in order to measure the empirical relations between the territorial capital and the change in the provincial performance. The intent is to measure how the territorial capital endowment might have determined different reactions on a sub-regional scale and, conversely, how the crisis might influence the territorial capital in different areas. If, on one hand, we expect that the “soft” dimensions of the territorial capital (relations among firms, cooperation networks, public-private partnership, territorial governance, innovation linkages, and so on) have some relevance in shaping the growth process of less developed and peripheral areas, the role of these dimensions in the reaction to crisis is still to be debated. The paper examines the relation between territorial capital and performance at NUTS-3 (provincial) level. during the period 1999-2011 and on the basis of exports and employment dynamics

    Contributo alla flora del Parco Nazionale della Majella

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    Viene presentato un ulteriore contributo alla ricca flora del Parco Nazionale della Majella. In particolare, 15 nuove entità vengono segnalate per la prima volta ed una viene confermata nell’area protetta. Per altre entità, rare sul territorio regionale, vengono segnalate nuove stazioni all’interno del Parco. Il contributo conferma come la ricerca sul campo sia di fondamentale importanza per approfondire le conoscenze sul patrimonio naturale, anche nel caso di territori abbastanza ben conosciuti come quello del Parco Nazionale della Majella.A further contribution to the rich flora of the Majella National Park is presented. In particular, 15 entities are reported for the first time and one is confirmed in the protected area. New localities are also indicated, inside the Park, for some plant species that are very rare in the Abruzzo region. It is confirmed that field research is of crucial importance in expanding our knowledge of the natural heritage, even in a fairly well known territory as that of the Majella National Park

    Colecistectomia laparoscopica in situs viscerum inversus totalis: nota di tecnica

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    The Authors report the case of a patient admitted in Emergency Room for biliary colic. She knew her dextrocardia. ECG and chest X-ray confirmed the dextrocardia. Ultrasonography and CT scan discovered a situs viscerum inversus totalis and cholecystolithiasis responsible of the abdominal colic. Laparoscopic cholecystectomy was performed. The Authors discuss the clinical case and the particular technique used

    Assessing radiative transfer models trained by numerical weather forecasts using sun-tracking radiometric measurements for satellite link characterization up to W band

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    Radio communications, and in particular Earth-to-satellite links, are worldwide used for delivering digital services. The bandwidth demand of such services is increasing accordingly to the advent of more advanced applications (e.g., multimedia services, deep-space explorations, etc.) thus pushing the scientific community toward the investigation of channel carriers at higher frequencies. When using carrier frequencies above X band, the main drawback is how to tackle the impact of tropospheric processes (i.e., rain, cloud, water vapor). This work assesses the joint use of weather forecast models, radiative transfer models and Sun-tracking radiometric measurements to explore their potential benefits in predicting path attenuation and sky noise temperature for slant paths at frequencies between K and W band, thus paving the way to the optimization of satellite link-budgets

    Study of aerobic granular sludge stability in a continuous-flow membrane bioreactor

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    A granular continuous-flow membrane bioreactor with a novel hydrodynamic configuration was developed to evaluate the stability of aerobic granular sludge (AGS). Under continuous-flow operation (Period I), AGS rapidly lost their structural integrity resulting in loose and fluffy microbial aggregates in which filamentous bacteria were dominant. The intermittent feeding (Period II) allowed obtaining the succession of feast and famine conditions that favored the increase in AGS stability. Although no further breakage occurred, the formation of new granules was very limited, owing to the absence of the hydraulic selection pressure. These results noted the necessity to ensure, on the one hand the succession of feast/famine conditions, and on the other, the hydraulic selection pressure that allows flocculent sludge washout. This preliminary study shows that the proposed configuration could meet the first aspect; in contrast, biomass selection needs to be improved
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