2,378 research outputs found
Application of the Rotation Matrix Natural Invariants to Impedance Control of Rotational Parallel Robots
Force control of parallel robots with rotational degrees of freedom through impedance algorithms is considerably influenced by the representation method of the end-effector orientation. Using the natural invariants of the rotation matrix and the angular velocity vector in the impedance control law has some theoretical advantages, which derive from the Euclidean-geometric meaning of these entities. These benefits are particularly evident in case of robotic architectures with three rotational degrees of freedom (serial or parallel wrists with spherical motion). The behaviour of a 3-CPU parallel robot controlled by an impedance algorithm based on this concepts is assessed through multibody simulations, and the results confirm the effectiveness of the proposed approach
Prediction of forest aboveground biomass using multitemporal multispectral remote sensing data
Forest aboveground biomass (AGB) is a prime forest parameter that requires global level estimates to study the global carbon cycle. Light detection and ranging (LiDAR) is the state-of-the-art technology for AGB prediction but it is expensive, and its coverage is restricted to small areas. On the contrary, spaceborne Earth observation data are effective and economical information sources to estimate and monitor AGB at a large scale. In this paper, we present a study on the use of different spaceborne multispectral remote sensing data for the prediction of forest AGB. The objective is to evaluate the effects of temporal, spectral, and spatial capacities of multispectral satellite data for AGB prediction. The study was performed on multispectral data acquired by Sentinel-2, RapidEye, and Dove satellites which are characterized by different spatial resolutions, temporal availability, and number of spectral bands. A systematic process of least absolute shrinkage and selection operator (lasso) variable selection generalized linear modeling, leave-one-out cross-validation, and analysis was accomplished on each satellite dataset for AGB prediction. Results point out that the multitemporal data based AGB models were more effective in prediction than the single-time models. In addition, red-edge and short wave infrared (SWIR) channel dependent variables showed significant improvement in the modeling results and contributed to more than 50% of the selected variables. Results also suggest that high spatial resolution plays a smaller role than spectral and temporal information in the prediction of AGB. The overall analysis emphasizes a good potential of spaceborne multispectral data for developing sophisticated methods for AGB prediction especially with specific spectral channels and temporal informatio
El crimen de los oligarcas corcirenses (Th. III 70.4)
At Th. 3.70.4, a number of Corcyraean oligarchs are convicted of illegally ‘cutting stakes’ (τέμνειν χάρακας) in two local sanctuaries. The significance of this charge is disputed among commentators. We offer detailed support of Hornblower’s conclusion that the Corcyraean oligarchs are charged with cutting saplings from sacred land for use as vine-stakes in their own fields. Our argument places Thucydides’ account of events in a larger philological, ecological and social framework, and suggests that the details of the accusation help establish abuse of communally controlled natural resources and the court system as prodromal stages in the social deterioration that ultimately produces the stasis on Corcyra and by implication elsewhere as well.En Th. III 70.4 se acusa a un grupo de oligarcas de Corcira por ‘cortar estacas’ (τέμνειν χάρακας) ilegalmente en dos santuarios locales. Los comentaristas discuten el significado de esta acusación. Ofrecemos apoyo detallado a la conclusión de Hornblower, según la cual se acusa a los oligarcas corcirenses de cortar árboles jóvenes de terreno sagrado para usarlos como puntales de viñas en sus campos privados. Nuestro argumento sitúa el relato de Tucídides en un marco filológico, ecológico y social más amplio, y sugiere que los detalles de la acusación ayudan a establecer el abuso de recursos naturales controlados por la comunidad y el sistema judicial como fases preliminares en el deterioro social que terminó produciendo la stasis en Corcira e implícitamente también en otros lugares
Word of Mouth, Viral Marketing and Open Data: A Large-Scale Simulation for Predicting Opinion Diffusion on Ethical Food Consumption
The file attached to this record is the author's final peer reviewed version. The Publisher's final version can be found by following the DOI link.This paper presents the first results of a large-scale-Agent-Based Simulation devoted to simulate individual behaviour inside a medium sized city (600,000 inhabitants). Humans are simulated as Intelligent Individual entities characterized by several attributes created from the Open Data available by means of a multi-layer approach. The work presented is divided into two main parts: the first part aims to describe the multi-layer approach adopted with the inclusion of the social network layer devoted to capture how social networks can be correlated with human activities and how an “Individual Opinion” can changes based on social interactions. The second part is devoted to present a preliminary case study for simulating the propagation dynamics of the individual opinion in the form of an ethical value function. The basic idea is to capture the changes in the individual opinion based on the social interactions predicted by the simulation. Finally, a food choice model for predicting individual choices based on the individual opinion function is presented; the model is based on three parameters: accessibility of ethical shops, price difference with standard products, and ethical value propagation
New Perspectives in Manufacturing: An Assessment for an Advanced Reconfigurable Machining System
Traditionally manufacturing cycle involves several production processes that are carried out according to the required technologies tacking into account the constraint due to the production capacity provided by machine tools and the customers' orders time schedule In this paper, a new modular, reconfigurable and scalable machining centre is presented. The resulting system is characterized by the possibility of modifying the machining capacity as well as exchanging the role between workpieces and machining/operating resources. This augmented flexibility creates new opportunities for efficient manufacturing; however, the increased system complexity demands a new approach for the jobs scheduling and machining control. An architecture based on agents modelling is proposed and discussed
Mind, machines and manufacturing: a philosophical essay on machining
Manufacturing evolution provided more and more efficient techniques to extend the anthropometric capabilities of humans. From the Neolithic Revolution to the Digital Revolution, passing through Renaissance and the Industrial Revolution, men invented new tools/systems to achieve objectives covering all the Maslow\u2019s hierarchy of needs: physiological, psychological, self-fulfillment needs.
Nowadays, the complexity of society, manufacturing and information technology as well as industry makes challenging to delineate a comprehensive framework of the machining processes that could indicate the trend of the fabrication industry.
This paper will provide an historical perspective of the manufacturing industry and its co-evolution in the actual society. In particular, a parallel between the advancement of computer science, information technologies and the machining processes will be presented by considering the description tools provided by different research areas
A decision support system for disaster prevention in Urban Areas
This paper presents the use of Human Behavior Modeling for Disaster Relief and Emergency Management. The authors propose an innovative MS2G (Modeling, Interoperable Simulation and Serious Game) using Intelligent Agents to reproduce a complex scenario used for Verification, Validation and Accreditation of the approach. The case study is inspired to South Sudan situation and to the necessity to provide accommodations, food, health care services, security and administrative support to a large number of IDPs (Internally Displaced Persons) over a wide area.
The simulator includes camp preparation and installation, air dr ops, logistics network creation while the model includes populations, entities and units as well as different equipment (e.g. cargo planes, helicopters, ground units, etc.
Design and construction of a modular pump-jet thruster for autonomous surface vehicle operations in extremely shallow water
open5noThis paper describes a customized thruster for Autonomous Surface Vehicles (ASV). The thruster is a Pump-Jet Module (PJM), which has been expressly designed, modeled, constructed, and tested for small-/medium-sized ASVs that perform environmental monitoring in extremely shallow waters such as wetlands (rivers, lakes, swamps, marshes), where water depth is only a few centimeters. The PJM is a fully-electric propulsion unit with a 360-degree continuous steering capability. Its main advantage is that the unit is flush with the flat bottom of the vehicle. This makes the PJM suitable for operation in extremely shallow waters because the risk of damaging the thrusting unit in case of grounding is very limited. The PJM was produced using innovative materials, and the hydraulic components were all constructed using a 3D printer.openOdetti A.; Altosole M.; Bruzzone G.; Caccia M.; Viviani M.Odetti, Angelo; Altosole, M.; Bruzzone, G.; Caccia, M.; Viviani, M
Shaping flood risk governance through science-policy interfaces: insights from England, France and The Netherlands
In the face of increasing threats from flooding, there are growing calls to strengthen and improve arrangements of flood risk governance (FRG). This endeavour requires an appreciation of the multitude of factors stabilising and driving governance dynamics. So-called catalyst flood events, policy champions and advocacy coalitions have tended to dominate this study to date, whilst the potential role played by Science Policy Interfaces (SPIs) has been somewhat neglected and often approached in a reductionist and fragmented way. This paper addresses this gap by drawing from in-depth policy analysis and stakeholder interviews conducted within England, France and the Netherlands under the auspices of the EU-FP7 STAR-FLOOD project. The analysis reveals four prominent ways in which SPIs shape FRG, by i) facilitating the diversification of Flood Risk Management (FRM) strategies; ii) increasing their connectivity, iii) facilitating a decentralisation of FRM and iv) fostering inter-country learning. It identifies different roles of specific interfaces (structures) and interfacing mechanisms (processes) in shaping governance dynamics. This way, the analysis reveals various ‘entry points’ through which SPIs can steer FRG, either along existing pathways, or towards new and potentially transformative change. The study shows that SPIs are a hitherto underexposed factor explaining dynamics in flood risk governance which merits additional systematic empirical study
Class II ADP-ribosylation factors are required for efficient secretion of Dengue viruses
This article is available open access through the publisher’s website.Identification and characterization of virus-host interactions are very important steps toward a better understanding of the molecular mechanisms responsible for disease progression and pathogenesis. To date, very few cellular factors involved in the life cycle of flaviviruses, which are important human pathogens, have been described. In this study, we demonstrate a crucial role for class II Arf proteins (Arf4 and Arf5) in the dengue flavivirus life cycle. We show that simultaneous depletion of Arf4 and Arf5 blocks recombinant subviral particle secretion for all four dengue serotypes. Immunostaining analysis suggests that class II Arf proteins are required at an early pre-Golgi step for dengue virus secretion. Using a horseradish peroxidase protein fused to a signal peptide, we show that class II Arfs act specifically on dengue virus secretion without altering the secretion of proteins through the constitutive secretory pathway. Co-immunoprecipitation data demonstrate that the dengue prM glycoprotein interacts with class II Arf proteins but not through its C-terminal VXPX motif. Finally, experiments performed with replication-competent dengue and yellow fever viruses demonstrate that the depletion of class II Arfs inhibits virus secretion, thus confirming their implication in the virus life cycle, although data obtained with West Nile virus pointed out the differences in virus-host interactions among flaviviruses. Our findings shed new light on a molecular mechanism used by dengue viruses during the late stages of the life cycle and demonstrate a novel function for class II Arf proteins.Research Fund for Control of Infectious Diseases of Hong Kong and BNP Paribas Corporate and Investment Banking
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