143 research outputs found

    Uncooperative Objects Pose, Motion and Inertia Tensor Estimation via Stereovision

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    Autonomous close proximity operations are an arduous and attractive problem in space mission design. In particular, the estimation of pose, motion and inertia properties of an uncooperative object is a challenging task because of the lack of available a priori information. In addition, good computational performance is necessary for real applications. This paper develops a method to estimate the relative position, velocity, angular velocity, attitude and inertia properties of an uncooperative space object using only stereo-vision measurements. The classical Extended Kalman Filter (EKF) and an Iterated Extended Kalman Filter (IEKF) are used and compared for the estimation procedure. The relative simplicity and low computational cost of the proposed algorithm allow for an online implementation for real applications. The developed algorithm is validated by numerical simulations in MATLAB using different initial conditions and uncertainty levels. The goal of the simulations is to verify the accuracy and robustness of the proposed estimation algorithm. The obtained results show satisfactory convergence of the estimation errors for all the considered quantities. An analysis of the computational cost is addressed to confirm the possibility of an onboard application. The obtained results, in several simulations, outperform similar works present in literature. In addition, a video processing procedure is presented to reconstruct the geometrical properties of a body using cameras. This method has been experimentally validated at the ADAMUS (ADvanced Autonomous MUltiple Spacecraft) Lab at the University of Florida

    European natural cements - their key technical properties under standardised conditions

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    The first comparative study on 7 commercially available Roman cements has been undertaken. In the absence of a European Standard, the testing procedures have followed a protocol proposed by the EU FP7 funded ROCARE project, which itself is based upon various ENs for cement and building limes. Evaluation has been made of mineralogy, particle size distribution, setting time, strength, water absorption, pore size distribution and mortar microstructure. Five of the cements required retardation and citric acid was used. The use of a pre-hydration technique was also investigated to extend the workable life of mortars to some 2 hours. The results confirm the view that the term Roman cement refers to a broad family of cements with a diverse range of properties which will need to be accounted for in future work to produce an all-encompassing Standard

    Gaining insight on mitigation of rubeosis iridis by UPARANT in a mouse model associated with proliferative retinopathy

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    Proliferative retinopathies (PR) lead to an increase in neovascularization and inflammation factors, at times culminating in pathologic rubeosis iridis (RI). In mice, uveal puncture combined with injection of hypoxia-conditioned media mimics RI associated with proliferative retinopathies. Here, we investigated the effects of the urokinase plasminogen activator receptor (uPAR) antagonist-UPARANT-on the angiogenic and inflammatory processes that are dysregulated in this model. In addition, the effects of UPARANT were compared with those of anti-vascular endothelial growth factor (VEGF) therapies. Administration of UPARANT promptly decreased iris vasculature, while anti-VEGF effects were slower and less pronounced. Immunoblot and qPCR analysis suggested that UPARANT acts predominantly by reducing the upregulated inflammatory and extracellular matrix degradation responses. UPARANT appears to be more effective in comparison to anti-VEGF in the treatment of RI associated with PR in the murine model, by modulating multiple uPAR-associated signaling pathways. Furthermore, UPARANT effectiveness was maintained when systemically administered, which could open to novel improved therapies for proliferative ocular diseases, particularly those associated with PR. KEY MESSAGES: • Further evidence of UPARANT effectiveness in normalizing pathological iris neovascularization. • Both systemic and local administration of UPARANT reduce iris neovascularization in a model associated with proliferative retinopathies. • In the mouse models of rubeosis iridis associated with proliferative retinopathy, UPARANT displays stronger effects when compared with anti-vascular endothelial growth factor regimen

    Lice (Haematopinus tuberculatus) in water buffalo farms from central Italy

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    The aim of the present study was to obtain information about the presence and distribution of the suckling louse Haematopinus tuberculatus in water buffalo farms in central Italy. The survey was carried out on 127 farms (epidemiological units), selected using a grid approach within a Geographical Information System, followed by proportional allocation. In each farm 6 buffaloes were examined in order to detect the louse presence. Parasitological examinations were performed on each buffalo at predilection sites. A total of 762 water buffaloes were examined. H. tuberculatus was found in the 11.0% (14/127) of the farms and in the 4.5% (34/762) of the animals. The presence H. tuberculatus should be routinely considered because it is a cause of serious health, production and economic damages in intensive breeding buffaloes

    A Highly Integrated Navigation Unit for On-Orbit Servicing Missions

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    VINAG (VISION/INS integrated Navigation Assisted by GNSS) is a highly integrated multisensor navigation unit, particularly conceived for On-Orbit Servicing missions. The system is designed to provide all-in-one, on-board real time autonomous absolute navigation as well as pose determination of an uncooperative known object orbiting in LEO (Low Earth Orbit), GEO (GEosynchronous Orbits) and possibly in HEO (Highly Earth Orbit). The system VINAG is under development by a team of Italian companies and universities, co-financed by the Italian Space Agency. Thanks to a tight optimized integration of its subsystems, VINAG is characterized by a low power and mass total budgets and therefore it is suitable for small and very small satellites. In order to provide both 1) absolute orbit and attitude determination and 2) vision-based pose determination, the unit integrates three metrology systems: a Cameras Subsystem (a monocular camera and a Star sensor), an Inertial Measurement Unit (IMU) and a GNSS (Global Navigation Satellite System) receiver. In this paper, we introduce the complete system architecture, the adopted algorithms and then the adopted hardware design solutions. In addition, we describe preliminary numerical simulation results obtained for different orbits from LEO to GEO carried out for the validation phase of VINAG

    After the first lockdown due to the COVID-19 pandemic: Perceptions, experiences, and effects on well-being in Italian people

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    BackgroundSince the COVID-19 pandemic and the subsequent measures of containment, multiple studies have been conducted aimed at assessing the impacts on people’s psychophysical well-being; however, few studies have investigated the general population’s perceptions, experiences, and effects by adopting a mixed-method approach.MethodsA total of 855 Italian participants completed an online survey, conducted in the period following the first lockdown in Italy. Psychological well-being, perceived stress and COVID-19-related fears were assessed by standardized questionnaires (Psychological General Well-Being Index-Short version, Perceived Stress Scale 10, and Multidimensional Assessment of COVID-19-Related Fears). The process of sense-making of the experience during the lockdown period was also evaluated by means of an open-ended question.ResultsParticipants reported a lower level of general well-being, and a higher level of both perceived stress and COVID-19-related fear during the lockdown period compared to the time of the survey (1 month after the resumption of activities). The thematic analysis of responses to the open-ended question revealed two factors and five clusters, which explain the thematic variance among the narratives: the first factor refers to the type of experience (emotional states and feelings vs. objective descriptions of daily activities), while the second concerns positive or negative connotations of the experiences reported.ConclusionsThis study explored the psychological impact of the first lockdown on people’s well-being, and described the process of making sense of the experience during the lockdown 1 month after going back to previous habits. Results highlighted the effectiveness of the mixed-method approach for an in-depth and exhaustive investigation of people’s psychological condition during and after the first lockdown
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