303 research outputs found
Cubesat mission with technological demonstrator payload for high data rate downlink and health monitoring
The HyperCube payload will be composed by two different technological experiment, an high data-rate C band antenna, and a demonstrator for a remote structural health monitoring system.
The first one has been thought with the aim to give Cubesats the capability to download an high quantity of data; it could be useful either if the data requiring the high data-rate downlink is on-board generated or simply retransmitted. The applications for which this payload could be used are several; an example
for the first category of application is to download the data generated by another payload; the high data-rate capability could be necessary due to the narrow visibility window with the ground station, affected also by the absence of an active AOCS subsystem, which makes difficult the alignment of the on board
antenna with the ground one. But the C band antenna could also be used to act as a “space–repeater”, downloading up–linked
information. The second payload is related to the need to
take under strictly control the health of the structures (not only the ones strictly belonging to primary structures, but also that
of any subsystem component). In order to do that, smart materials are integrated into the structural component that need to be monitored; in particular, piezoelectric patches are used as sensors. As the structure is stressed, and the integrated piezoelectric sensors are subjected to mechanical deformation, they produce an electric signal; acquiring and properly studying the produced signal it is possible to monitor the mechanical
condition of the structures. The health monitoring system is completed by a MicroController Unit which acquires, samples
and stores the signal produced, and a transmitting system, which could be the C band antenna, or the TT&C antenna which
each satellite needs
Self-presentation and emotional contagion on Facebook: new experimental measures of profiles' emotional coherence
Social Networks allow users to self-present by sharing personal contents with
others which may add comments. Recent studies highlighted how the emotions
expressed in a post affect others' posts, eliciting a congruent emotion. So
far, no studies have yet investigated the emotional coherence between wall
posts and its comments. This research evaluated posts and comments mood of
Facebook profiles, analyzing their linguistic features, and a measure to assess
an excessive self-presentation was introduced. Two new experimental measures
were built, describing the emotional loading (positive and negative) of posts
and comments, and the mood correspondence between them was evaluated. The
profiles "empathy", the mood coherence between post and comments, was used to
investigate the relation between an excessive self-presentation and the
emotional coherence of a profile. Participants publish a higher average number
of posts with positive mood. To publish an emotional post corresponds to get
more likes, comments and receive a coherent mood of comments, confirming the
emotional contagion effect reported in literature. Finally, the more empathetic
profiles are characterized by an excessive self-presentation, having more
posts, and receiving more comments and likes. To publish emotional contents
appears to be functional to receive more comments and likes, fulfilling needs
of attention-seeking.Comment: Submitted to Complexit
Innovative solution for reducing the run-down time of the chipper disc using a brake clamp device
Wood-chippers are widely used machines in the forestry, urban and agricultural sectors. The use of these machines implies various risks for workers, primarily the risk of contact with moving and cutting parts. These machine parts have a high moment of inertia that can lead to entrainment with the cutting components. This risk is particularly high in the case of manually fed chippers. Following cases of injury with wood-chippers and the improvement of the technical standard (Comit\ue9Europ\ue9en de Normalisation-European Norm) EN 13525: 2005 + A2: 2009, this technical note presents the prototype of an innovative system to reduce risks related to the involved moving parts, based on the \u201cbrake caliper\u201d system and electromagnetic clutch for the declutching of the power take-off (PTO). The prototype has demonstrated its potential for reducing the run-down time of the chipper disc (95%) and for reducing the worker\u2019s risk of entanglement and entrainment in the machine\u2019s feed mouth
Innovative solution for reducing the run-down time of the chipper disc using a brake clamp device
Wood-chippers are widely used machines in the forestry, urban and agricultural sectors. The use of these machines implies various risks for workers, primarily the risk of contact with moving and cutting parts. These machine parts have a high moment of inertia that can lead to entrainment with the cutting components. This risk is particularly high in the case of manually fed chippers. Following cases of injury with wood-chippers and the improvement of the technical standard (ComitéEuropéen de Normalisation-European Norm) EN 13525: 2005 + A2: 2009, this technical note presents the prototype of an innovative system to reduce risks related to the involved moving parts, based on the “brake caliper” system and electromagnetic clutch for the declutching of the power take-off (PTO). The prototype has demonstrated its potential for reducing the run-down time of the chipper disc (95%) and for reducing the worker’s risk of entanglement and entrainment in the machine’s feed mouth
High-accuracy digital elevation model generation and ship monitoring from synthetic aperture radar images: innovative techniques and experimental results.
In this Thesis several state-of-the-art and innovative techniques for Digital Elevation Model (DEM) generation from Synthetic Aperture Radar (SAR) images are deeply analyzed, with a special focus on the methods which allow the improvement of the accuracy of the DEM product, which is directly related to the geolocation accuracy of geocoded images and is considered as an enabling factor for a large series of civilian and Defence applications. Furthermore, some of the proposed techniques, which are based both on phase and amplitude information, are experimented on real data, i.e. COSMO-SkyMed (CSK) data, assessing the achievable performances compared with the state-of-the-art, and pointing out and quantitatively highlighting the acquisition and processing strategies which would allow to maximize the quality of the results. Moreover, a critical analysis is performed about the main errors affecting the applied techniques, as well as the limitations of the orbital configurations, identifying several complementary techniques which would allow to overcome or mitigate the observed drawbacks. An innovative procedure for on-demand DEM production from CSK SAR data is elaborated and proposed, as well as an auto-validation technique which would enable the validation of the produced DEM also where vertical ground truths are not available. Based on the obtained results and on the consequent critical analysis, several interferometric specifications for new generation SAR satellites are identified. Finally, a literature review is proposed about the main state-of-the-art ship monitoring techniques, considered as one of the main fields of application which takes benefit from SAR data, based on single/multi-platform multi-channel SAR data, with a focus on TanDEM-X (TDX).
In particular, in Chapter 1 the main concepts concerning SAR operating principles are introduced and the main characteristics and performances of CSK and TDX satellite systems are described; in Chapter 2 a review is proposed about the state-of-the-art SAR interferometric techniques for DEM generation, analyzing all the relevant processing steps and deepening the study of the main solutions recently proposed in the literature to increase the accuracy of the interferometric processing; in Chapter 3 complementary and innovative techniques respect to the interferometric processing are analyzed to mitigate disadvantages and to improve performances; in Chapter 4 experimental results are presented, obtained in the generation of high accuracy DEM by applying to a dataset of CSK images properly selected state-of-the-art interferometric techniques and innovative methods to improve DEM accuracy, exploring relevant limitations, and pointing out innovative acquisition and processing strategies. In Chapter 5, the basic principles of Ground Moving Target Indication (GMTI) are described, focusing on Displaced Phase Center Antenna (DPCA) and Along-Track Interferometry (ATI) techniques
METROPOLITAN AGRICULTURE, SOCIO-DEMOGRAPHIC DYNAMICS AND THE FOOD-CITY RELATIONSHIP IN SOUTHERN EUROPE
Peri-urban agriculture is a pivotal issue in the debate on sustainable
management of land in metropolitan regions worldwide. Multiple socioeconomic
and environmental solutions introduced by new models of peri-urban agriculture
are playing an important role in planning and management of fringe land. The
recent development of peri-urban agriculture in Southern European cities was
supposed to reflect latent, crisis-driven processes of 'coming back to land': new
land has been extensively cultivated, and new relations have been created between
farmers, communities and territories within peri-urban areas. This study describes
some relevant experiences of peri-urban farming in 6 metropolitan regions
(Lisbon, Barcelona, Marseille, Rome, Athens, Istanbul) representative of different
socioeconomic contexts in Southern Europe, outlining strengths and weaknesses in
the use of fringe land for cropping, and evidencing relevant implications for urban
sustainability
Study on an air-launched constellation of tactical micro-satellites for defence Use
The great attention on air-launched microsatellites is due on one hand to the possibilities given by the miniaturization push, making the same performances of traditional satellites achievable with smaller systems, and on the other hand to the disruptive advantages allowed by air-launch techniques, providing Italy not only with an autonomous launch capability, but also with the flexibility to choose the orbit inclination and the launch time, enabling a responsive approach at lower costs respect to ground based launches. In this study, several issues related to this subject are analyzed. A constellation of four microsatellites for
electro-optical Earth Observation (EO) is conceived, namely ITAFÎĽSAT (i.e. ITalian Tactical Formation of ÎĽ-SATellites). ITAFÎĽSAT is designed to achieve a sub-metric spatial resolution and to offer a high revisit frequency on a specified target area to satisfy military needs. ITAFÎĽSAT is designed to be responsive and the system is conceived to guarantee a fast access to space since the mission is called, through a Plug-and-Play (PnP) approach; to provide Italy with a proprietary system, built, launched and operated on-purpose for its contingent needs; and to complete the information supplied by other EO systems with high quality images captured in a very short time
Online citizen reporting on urban maintenance: a collection, evaluation and decision support system
We present an online support system for urban maintenance which: 1. lets citizens directly report neighbourhood issues which may require attention from the urban maintenance services: 2. evaluates the priority of reported issues; 3. allows the allocation and management of resources and workforce on solving issues and 4. permits public tracking of their status.
The web application was entirely developed using low-cost Google cloud services, with the advantage of low deployment and hosting costs and practically no systems administration costs, a highly replicable and transferrable solution, and a rapid development process relying on robust Google services. The model for evaluating priority of reported issues is based on the the ELECTRE TRI rating method.
In the paper we present the system's standard workflow, the evaluation model and the implementation details. We also discuss its possible more general implications for fostering and supporting citizens participation. Unlike many existing platforms for citizens reporting of maintenance issues, our system incorporates an explicit and publicly accessible evaluation model to prioritise issues and assign resources for their solution. This, we argue, is a crucial prerequisite for the principles of transparency, publicity, accountability and equity be observed by municipal governments
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