3,959 research outputs found

    Development and flight test of an avionics LIDAR for helicopter and UAV low-level flight

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    In recent years, laser radar (LIDAR) has become a promising technology for navigation and obstacle avoidance in helicopters and UAV, mainly because of its good wire detection performance on a wide range of incidence angles, and also due to its outstanding range and accuracy. In this paper we describe the activities carried out for the design, integration and test of the Laser Obstacle Avoidance System 'Marconi' (LOAM) on helicopter and UAV platforms. After a brief description of the system architecture and sensor characteristics, emphasis is given to the performance models and processing algorithms required for obstacle detection/classification and calculation of alternative flight paths, as well as to the ground and flight test activities performed on various platforms

    High Contrast Imaging in the Visible: First Experimental Results at the Large Binocular Telescope

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    In February 2014, the SHARK-VIS (System for High contrast And coronography from R to K at VISual bands) Forerunner, a high contrast experimental imager operating at visible wavelengths, was installed at LBT (Large Binocular Telescope). Here we report on the first results obtained by recent on-sky tests. These results show the extremely good performance of the LBT ExAO (Extreme Adaptive Optics) system at visible wavelengths, both in terms of spatial resolution and contrast achieved. Similarly to what was done by (Amara et al. 2012), we used the SHARK-VIS Forerunner data to quantitatively assess the contrast enhancement. This is done by injecting several different synthetic faint objects in the acquired data and applying the ADI (angular differential imaging) technique. A contrast of the order of 5×1055 \times 10^{-5} is obtained at 630 nm for angular separations from the star larger than 100 mas. These results are discussed in light of the future development of SHARK-VIS and compared to those obtained by other high contrast imagers operating at similar wavelengths.Comment: Astronomical Journal - Accepted for publicatio

    A retrospective study on the artificial mummification of the Blessed Andrea da Montereale (AD 1479)

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    Andrea da Montereale was a 15th Century Augustinian monk from the inner Abruzzo region, central Italy. We investigated the preservation mechanisms of his body by retrospective survey of textual sources and reports from the Canonical Recognitions. The partially mummified body of the Blessed Andrea da Montereale revealed indisputable evidence of artificial mummification (excerebration and evisceration cuts, absence of internal organs) at visual inspection. The cadaver features emphasized by the hagiographers (vivid colours, absence of putrefaction or bad smelling for thirty days after death, without balsams treatments) sounds like an unrequested explanation for the body miraculous preservation. To the best of our knowledge, this represents the twelfth known case of an embalmed body in Catholic Religion, the tenth in Central Italy, and the second one documented in the Abruzzo regio

    Changing patterns of conflict between humans, carnivores and crop-raiding prey as large carnivores recolonize human-dominated landscapes

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    Large carnivores are making remarkable comebacks in Europe, but how this affects human-wildlife conflict remains unclear. Rebounding carnivore populations lead to increasing livestock depredation, which in turn leads to greater economic losses for farmers. However, returning carnivores could also influence the behavior of wild ungulates, which are themselves responsible for major crop damage and associated economic losses. Here, we exploit the natural experiment of a rebounding wolf population in the Italian Apennines to study how this affected both types of human-wildlife conflic. We used large datasets of wolf occurrences (n = 351), livestock depredation events (n = 165), and crop damage events by wild boar (n = 3442) to independently model the determinants of livestock depredation and crop damage distribution in relation to wolf habitat suitability over a ten-year period of increasing wolf numbers. These analyses yielded two major insights. First, livestock depredations were mainly related to insufficient prevention measures (e.g. lacking fencing) rather than landscape context, providing a clear pathway to conflict mitigation. Second, crop damage decreased in areas of higher wolf habitat suitability and became more likely in areas of lower wolf habitat suitability, closer to settlements. This suggests increasing predation pressure forces wild boars to avoid the most suitable wolf habitat, leading to a redistribution of crop damage in the landscape. More generally, our study highlights complex human-wildlife interactions as large carnivores recover in human-dominated landscapes, suggesting that multiple, cooccurring conflicts need to be assessed jointly and adaptively in order to foster coexistence between humans and wildlife

    Gamma-ray observations of Cygnus X-1 above 100 MeV in the hard and soft states

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    We present the results of multi-year gamma-ray observations by the AGILE satellite of the black hole binary system Cygnus X-1. In a previous investigation we focused on gamma-ray observations of Cygnus X-1 in the hard state during the period mid-2007/2009. Here we present the results of the gamma-ray monitoring of Cygnus X-1 during the period 2010/mid-2012 carried out for which includes a remarkably prolonged `soft state' phase (June 2010 -- May 2011). Previous 1--10 MeV observations of Cyg X-1 in this state hinted at a possible existence of a non-thermal particle component with substantial modifications of the Comptonized emission from the inner accretion disk. Our AGILE data, averaged over the mid-2010/mid-2011 soft state of Cygnus X-1, provide a significant upper limit for gamma-ray emission above 100 MeV of F_soft < 20 x 10^{-8} ph/cm^2/s, excluding the existence of prominent non-thermal emission above 100 MeV during the soft state of Cygnus X-1. We discuss theoretical implications of our findings in the context of high-energy emission models of black hole accretion. We also discuss possible gamma-ray flares detected by AGILE. In addition to a previously reported episode observed by AGILE in October 2009 during the hard state, we report a weak but important candidate for enhanced emission which occurred at the end of June 2010 (2010-06-30 10:00 - 2010-07-02 10:00 UT) exactly in coincidence with a hard-to-soft state transition and before an anomalous radio flare. An appendix summarizes all previous high-energy observations and possible detections of Cygnus X-1 above 1 MeV.Comment: 16 pages, 12 figures, 1 table, accepted for publication in Ap

    Perception of Time-Discrete Haptic Feedback on the Waist is Invariant with Gait Events

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    The effectiveness of haptic feedback devices highly depends on the perception of tactile stimuli, which differs across body parts and can be affected by movement. In this study, a novel wearable sensory feedback apparatus made of a pair of pressure-sensitive insoles and a belt equipped with vibrotactile units is presented; the device provides time-discrete vibrations around the waist, synchronized with biomechanically-relevant gait events during walking. Experiments with fifteen healthy volunteers were carried out to investigate users' tactile perception on the waist. Stimuli of different intensities were provided at twelve locations, each time synchronously with one pre-defined gait event (i.e. heel strike, flat foot or toe off), following a pseudo-random stimulation sequence. Reaction time, detection rate and localization accuracy were analyzed as functions of the stimulation level and site and the effect of gait events on perception was investigated. Results revealed that above-threshold stimuli (i.e. vibrations characterized by acceleration amplitudes of 1.92g and 2.13g and frequencies of 100 Hz and 150 Hz, respectively) can be effectively perceived in all the sites and successfully localized when the intertactor spacing is set to 10 cm. Moreover, it was found that perception of time-discrete vibrations was not affected by phase-related gating mechanisms, suggesting that the waist could be considered as a preferred body region for delivering haptic feedback during walking

    The Lithium Salts of Bis(azolyl)borates as Strontium‐ and Chlorine‐free Red Pyrotechnic Colorants

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    After concerns regarding the use of chlorinated material for pyrotechnic items had reinforced, the action of the U.S. Environmental Protection Agency on health concerns about strontium ushered in a new era in the production of red light. Lithium was shown to impart red color to a pyrotechnic flame, however only a very narrow selection of such formulations can be found in the literature. Dihydrobis(azolyl)borates are a well investigated, easily accessible class of materials which have been proven to be suitable as pyrotechnic coloring agents. With their high nitrogen contents such moieties should also meet the requirements of a low combustion temperature and a reducing flame atmosphere for a lithium‐based red‐burning composition. This work evaluates the capability of the lithium salts of dihydrobis(pyrazol‐1‐yl)borate, dihydrobis(1,2,4‐triazol‐1‐yl)borate, and dihydrobis(tetrazol‐1‐yl)borate to serve as red color imparters. The latter compounds were characterized by multinuclear NMR experiments, IR spectroscopy, elemental analysis, and single‐crystal X‐ray diffraction and were investigated with respect to their thermal stabilities as well as sensitivities toward various ignition stimuli
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