86,664 research outputs found
Distributed SAR Chronogram and Timing Issues for RODiO Mission
No full textThis paper focuses on the timing analysis for a Distributed Synthetic Aperture Radar (DSAR) system exploiting an opportunity illuminator. This is the case of RODiO, which is a new mission concept funded by the Italian Space Agency (ASI) for a Phase A study in the framework of ALCOR program. RODiO's aim is to match the growing trend towards the miniaturization of satellites and new Synthetic Aperture Radar (SAR) applications. For this reason, RODiO consists in a cluster of four receiving-only CubeSats flying in a close formation and exploiting the independent PLATiNO-1 satellite as a transmitter. Because of the nature of RODiO mission, simultaneous observations with respect to the monostatic illuminator are needed. Through the comparison of monostatic and bistatic chronograms, a timing analysis is performed in the paper in order to assess the effects of DSAR geometry on simultaneous observation opportunities, aiding the design of the system
Biocompatibility and biodistribution of functionalized carbon nano-onions (f-CNOs) in a vertebrate model
No full textFunctionalized carbon nano-onions (f-CNOs) are of great interest as platforms for imaging, diagnostic and therapeutic applications due to their high cellular uptake and low cytotoxicity. To date, the toxicological effects of f-CNOs on vertebrates have not been reported. In this study, the possible biological impact of f-CNOs on zebrafish during development is investigated, evaluating different toxicity end-points such as the survival rate, hatching rate, and heart beat rate. Furthermore, a bio-distribution study of boron dipyrromethene (BODIPY) functionalized CNOs in zebrafish larvae is performed by utilizing inverted selective plane illumination microscopy (iSPIM), due to its intrinsic capability of allowing for fast 3D imaging. Our in vivo findings indicate that f-CNOs exhibit no toxicity, good biocompatibility (in the concentration range of 5-100 μg mL-1) and a homogenous biodistribution in zebrafish larvae
Preliminary product and system observational requirements for RODiO mission
No full textRODiO is an innovative mission concept selected by the Italian Space Agency (ASI) for a phase A study in the framework of the ALCOR program. RODiO consists of a cluster of 4 passive CubeSat receivers aiming to fly in a Large Baseline Bistatic (LBB) configuration with ASI PLATiNO-1 (PLT-1) Satellite. The mission objective is to serve as an in-orbit demonstrator of both the Distributed Synthetic Aperture Radar (DSAR) concept and a novel hybrid propellant rocket propulsion system for formation reconfiguration. RODiO also aims at delivering new SAR products for scientific and commercial downstream. The DSAR image resulting from the coherent combination of the stack of low performance bistatic data can be exploited to complement information from the monostatic image generated by the illuminator. The incoherent combination of these images allows for the demonstration of novel products. They are expected to actively contribute to several application ambits such as Digital Elevation Model (DEM) generation, Maritime Monitoring, and Civil Protection, Transport & Safety. Specifically, eight significant products have been identified: Radargrammetric DEM, Ship detection, Wake Analysis, Infrastructure Monitoring, Land Deformation Map, Flood Risk Map, Multi-baseline Radargrammetric DEM, and Multi-baseline Ship Velocity Map. Every product has then been characterized, leading to several observational requirements. The paper discusses the mission goals and the products identified as obtainable, focusing on the correspondent system observational requirements for their generation
RODIO Mission Status and Future Developments
No full textRODiO is an ASI Project based on an innovative mission concept developed in Italy by the University of Naples Federico II. The mission relies on a cluster of 4 CubeSats flying in formation with ASI PLATiNO-1 (PLT-1) SAR mission. The CubeSat cluster flies at a safe distance of tens of km from PLT-1, and formation-flying techniques are used to keep all the CubeSats in the cluster within an overall envelope of a few hundred meters. Each CubeSat embarks a receiving-only X-band SAR instrument able to collect bistatic echoes exploiting PLT-1 as an opportunity illuminator. In addition, one of the CubeSats embarks a novel hybrid rocket propulsion unit that enables high thrust (10 N) orbit reconfiguration. RODiO Phase A ended in December 2023 confirming mission feasibility and proposing solutions for radar antenna and deployment mechanisms, receiver electronics, hybrid propulsion unit and formation flying able to comply with a 16 U CubeSat
Long-baseline multistatic and bistatic SAR products: Application to the RODiO mission
No full textIn-Orbit Demonstration (IOD) missions represent flight opportunities to acquire data on spacecraft and space environment and to demonstrate new techniques at system, subsystem, and payload level. Realizing this type of mission means accepting a greater level of risk. However, when very compact and relatively simple platforms like CubeSats are adopted, this becomes admissible since costs can be kept low. Distributed Synthetic Aperture Radar (SAR) is a novel Earth Observation (EO) technique for microwave imaging. It uses multiple cooperating receivers and suitable processing to enable performance and products that exceed those of the single components of the system. RODiO (Radar for earth Observation by synthetic aperture Distributed on a cluster of CubeSats equipped with high-technology micro-propellers for new Operative services) is an IOD of the distributed SAR concept. The mission is based on four, 16 U, CubeSats, that embark a receiving-only X-band SAR instrument able to collect bistatic echoes exploiting a monostatic SAR as an opportunity illuminator, i.e PLATiNO-1 mission. Distributed SAR demonstration is thus pursued in RODiO combining the principles of both multistatic and bistatic SAR. The paper, moving from mission goals, individuates different families of EO products that RODiO can demonstrate, e.g. in the contest of ground motion, digital elevation models, and ship detection. The main result is the definition of the RODiO system requirements for product generation that drive satellites and payload design
On humans' (explicit) intuitions about the meaning of novel words
No full textPseudowords offer a unique opportunity to investigate how humans deal with new (verbal) information. Within this framework, previous studies have shown that, at the implicit level, humans exploit systematic associations in the form-meaning interface to process new information by relying on (sub-lexical) contents already mapped in semantic memory. However, whether speakers exploit such processes in explicit decisions about the meanings elicited by unfamiliar terms remains an open, important question. Here, we tested this by leveraging computational models that are able to induce semantic representations for out-of-vocabulary stimuli. Across two experiments, we demonstrate that participants' guesses about pseudoword meanings in a 2AFC task consistently align with the model's predictions. This indicates that humans' ability to extract meaningful knowledge from complex statistical patterns can affect explicit decisions
Advancing Radar Imaging and Earth Observation within the Alcor Program: RODiO and SATURN Missions
No full textIn the realm of space exploration, two pioneering missions within the ASI ALCOR Program are making significant strides. SATURN is a demonstration mission of a mini-swarm of 3 CubeSats in close formation on a Low Earth Dawn-Dusk Sun Synchronous Orbit, incorporating Multiple-Input-Multiple-Output (MIMO) technology for Earth Observation. CubeSats are equipped with Synthetic Aperture Radar (SAR), employing cooperative active sensors for enhanced performance. RODiO involves a cluster of four passive CubeSats flying in formation with ASI's PLATiNO-1 Synthetic Aperture Radar (SAR) mission. RODiO showcases Distributed Synthetic Aperture Radar (DSAR) technology, utilizing multi-platform image synthesis to enhance radar imagery quality
Federated Learning Under Heterogeneous and Correlated Client Availability
No full textIn Federated Learning (FL), devices - also referred to as clients - can exhibit heterogeneous availability patterns, often correlated over time and with other clients. This paper addresses the problem of heterogeneous and correlated client availability in FL. Our theoretical analysis is the first to demonstrate the negative impact of correlation on FL algorithms' convergence rate and highlights a trade-off between optimization error (related to convergence speed) and bias error (indicative of model quality). To optimize this trade-off, we propose Correlation-Aware FL (CA-Fed), a novel algorithm that dynamically balances the competing objectives of fast convergence and minimal model bias.
CA-Fed achieves this by dynamically adjusting the aggregation weight assigned to each client and selectively excluding clients with high temporal correlation and low availability.
Experimental evaluations on diverse datasets demonstrate the effectiveness of CA-Fed compared to state-of-the-art methods. Specifically, CA-Fed achieves the best trade-off between training time and test accuracy. By dynamically handling clients with high temporal correlation and low availability, CA-Fed emerges as a promising solution to mitigate the detrimental impact of correlated clien
Su alcuni profili problematici dei contratti esclusi
No full textLo studio si occupa del campo di applicazione del Codice dei contratti, che è delimitato dalle disposizioni contenute nel Titolo II della Parte I, agli artt. da 4 a 20, che individuano le fattispecie escluse, appunto, dalla applicazione del Codice
Le misure di accelerazione degli interventi infrastrutturali.
No full textEsame dell'art. 9 del D.L. n. 76/2020
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