196,801 research outputs found
Relative navigation in LEO by carrier-phase differential GPS with intersatellite ranging augmentation
No full textCarrier-phase differential GPS (CDGPS) is a promising technology for accurate relative navigation in LEO formations of cooperating satellites, but navigation filter robustness against poor GPS geometry and noisy measurements has to be improved. This can be performed by augmenting the navigation filter with intersatellite local ranging measurements, as the ones provided by ranging transponders or GNSS-like systems. In this paper, an augmented CDGPS navigation filter is proposed for the formation of two satellites characterized by a short, varying baseline, relevant to next generation Synthetic Aperture Radar missions. Specifically, a cascade-combination of dynamic and kinematic filters which processes double-differenced code and carrier measurements on two frequencies, as well as local inter-satellite ranging measurements, is used to get centimeter-level baseline estimates. The augmented filter is validated by numerical simulations of the formation orbital path. Results demonstrate that the proposed approach is effective in preserving the centimeter-level accuracy achievable by a CDGPS-only filter also in the presence of a poor GDOP or a limited number of GPS satellites in view. © 2013 Alfredo Renga et al
International Enciclopedia of Laws-Social Security: Italy
No full textGeneral Introduction. Developments over time in the social security system. Sources of the social security system. Scholars’ Theories. The institutions. Contribution and Financing. Health care. Family Allowances. Social insurance for invalidity. Industrial Accidents and Occupational Diseases. Unemployment. Pensions. Social Assistance. Protection of pension rights and contribution credits
Earth observation with MEO transmitters and UAS receivers: A potential utilization of Galileo constellation
No full textRemote sensing application of Galileo upcoming constellation in the field of civil security is preliminarily analyzed, defining low resolution (25 m) and high resolution (7.5 m) working modes for a bistatic Synthetic Aperture Radar system utilizing Galileo satellites as transmitters and Unmanned Aerial Systems as receivers. Simulations offshore Somali coast and in a South Mediterranean Sea region showed that both low and high resolution acquisitions are feasible. For the low resolution mode a probability of successful image formation no matter the azimuth position of the receiving UAS has been estimated at nearly 100%. Whereas, for the high resolution mode it decreases to about 90%, which, if deemed unsatisfactory for the application, leads to the need for UAS to adapt its route to the actual Galileo satellite coverag
Navigation facility for high accuracy offline trajectory and attitude estimation in airborne applications
No full textThe paper focuses on a navigation facility, relying on commercial-off-the- shelf (COTS) technology, developed to generate high-accuracy attitude and trajectory measurements in postprocessing. Target performance is cm-level positioning with tenth of degree attitude accuracy. The facility is based on the concept of GPS-aided inertial navigation but comprises carrier-phase differential GPS (CDGPS) processing and attitude estimation based on multiantenna GPS configurations. Expected applications of the system include: (a) performance assessment of integrated navigation systems, developed for general aviation aircraft and medium size unmanned aircraft systems (UAS); (b) generation of reference measurements to evaluate the flight performance of airborne sensors (e.g., radar or laser); and (c) generation of reference trajectory and attitude for improving imaging quality of airborne remote sensing data. The paper describes system architecture, selected algorithms for data processing and integration, and theoretical performance evaluation. Experimental results are also presented confirming the effectiveness of the implemented approach. © 2013 A. Renga et al
Dimensioning Renewable Energy Systems to Power Mobile Networks
No full textTo face the huge increase in the mobile traffic demand, denser cellular access networks are extensively deployed by mobile operators, entailing high cost for energy supply. Hence, renewable energy (RE) sources are often adopted to power base stations (BSs), in order to make them more self-sufficient and reduce the energy bill. Nevertheless, sizing an RE generation system is a critical task, and the dimensioning methods available in the literature are based on simulation or optimization approaches, hence resulting time consuming or computationally complex. This paper proposes and validates a simple still effective analytical method that, based on the location dependent mean value and variance of RE production, allows to find feasible combinations of photovoltaic (PV) panel and battery sizes, suitable to power a BS and decrease the storage depletion probability below a target threshold. Furthermore, the application of this method highlights the role of RE production variance. Higher values of the variance require larger PV panels, almost doubled with respect to locations with low variance. However, only locations with higher variance benefit from increasing the battery size and relaxing the constraint on energy self-sufficiency, with the scope of reducing the required PV panel capacity and the capital expenditures
Role of smart destination in hospitality enterprises sustainability: an empirical study on booking channels management and revenues
No full textThis paper draws on the literature on innovation in tourism industry to investigate how the promotional tools developed by destinations – websites for information and booking, apps, e-commerce websites, tourist cards, BI and CRM software – may contribute to long-term development of accommodations in the territory. It is assessed by analysing impacts on booking channels, direct and intermediated (both online and offline), and revenue. Hypotheses are tested with a generalized linear model and an ordered logistic regression on data retrieved from 1,226 accommodations distributed in the Italian territory. Empirical results evidence the contribution of smart destinations in increasing the competitiveness of the tourism firms in the same area
Definizione e sviluppo di modelli di calcolo da utilizzare per l'analisi ed il dimensionamento di strumenti radar ad apertura sintetica (SAR) frammentati, basati su configurazioni di tipo Bistatico (un trasmettitore ed un ricevitore piazzati su satelliti distinti) o Multistatico (un trasmettitore e ricevitori multipli piazzati su satelliti distinti
No full textRenga on the Way to Design Comfort and Leadership in The Russian Market
No full textВ статье рассматривается программа Renga как инновационный инструмент в области архитектурного проектирования и строительства, способствующий повышению комфорта проектирования и укреплению своих позиций на российском рынке. Анализируются основные функциональные характеристики Renga, такие как интуитивно понятный интерфейс, возможности совместной работы, поддержка BIM-технологий и автоматизация процессов, которые делают его привлекательным для архитекторов и инженеров. Обсуждаются факторы лидерства Renga, включая локализацию под российские стандарты, конкурентоспособные цены и поддержку со стороны государства. В сравнении с программным продуктом Autodesk Revit, Renga демонстрирует потенциал для дальнейшего развития и внедрения в практику проектирования, что открывает новые горизонты для пользователей и способствует цифровизации строительной отрасли.The article considers the Renga program as an innovative tool in the field of architectural design and construction, which helps to increase the comfort of design and strengthen its position in the Russian market. The main functional characteristics of Renga are analyzed, such as an intuitive interface, collaboration capabilities, support for BIM technologies and automation of processes that make it attractive to architects and engineers. The factors of Renga's leadership are discussed, including localization to Russian standards, competitive prices, and government support. In comparison with the Autodesk Revit software product, Renga demonstrates the potential for further development and implementation in design practice, which opens up new horizons for users and contributes to the digitalization of the construction industry
Household users cooperation to reduce cost in green mobile networks
No full textThe staggering mobile traffic growth is leading to a huge increase of operational costs for Mobile Operators (MOs) due to power supply. In a Smart Grid (SG) scenario, where Demand Response (DR) strategies are widely adopted to better balance the Demand-Supply mismatch, new opportunities arise for MOs, that can receive some monetary rewards for accomplishing the SG requests of periodically increasing or decreasing their energy consumption. This study considers a mobile network that exploits Renewable Energy (RE) to power the BSs and Resource on Demand (RoD) strategies to dynamically adapt the number of active radio resources to the varying traffic demand, in order to better react to the SG requests. On top of this, the purpose of this work is investigating the effects of the cooperation between Household Customers (HCs) engaged in the DR program and the mobile network. Based on a predefined agreement, HCs cooperate with the MO in order to increase its capability to accomplish the SG requests, receiving in return some benefits when stipulating the Internet provisioning contract with the MO. HCs can contribute to achieving the MO goals by means of two techniques. On the one hand, a fraction of the electric loads that are postponed by the HCs when the SG asks for a reduction of the energy consumption can be shifted on behalf of the mobile network, that will receive the corresponding monetary rewards (HC Trade - HCT). On the other hand, HCs can accept to handle some additional mobile traffic, that is moved to their own WiFi Access Points from the BSs, in order to reduce the energy load of the mobile network (WiFi Offloading - WO).Our results show that, although HCT alone provides limited saving in the energy bill due to the poor attitude of HCs to postpone their electric loads, up to 18% of cost saving can be achieved under full HCs cooperation when HCT is combined with WO. The effects of HCs cooperation can be further enhanced by installing larger sized RE generators, allowing to significantly reduce the energy bill up to more than 90%
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