386 research outputs found
Quattro nuove sculture di Prospero Clemente al Casino di Sotto di Novellara
No full textThe author examines four terracotta busts of women (one now irreparably damaged) set on
the entrance façade of the so-called Casino di Sotto in Novellara, proposing an attribution to
the sculptor Prospero Sogari, known as il Clemente, from Reggio Emilia. Alongside an analysis
of style, which highlights close affinities with the artist’s oeuvre, the article seeks to investigate
the original location of these busts. Although they now form part of a structure refurbished in
the eighteenth century, the Casino owes its original layout to Alfonso I Gonzaga, who entrusted
the design of the complex and its stuccoes and fireplaces to Lelio Orsi of Novellara in 1563.
Prompted by the links with this painter, the author concludes by expanding her argument to a
broader framing of these works in the context of Mannerism in Reggio
Close Approach Analysis in the Geosynchronous Region Using Optical Measurements
No full textEarth orbiting spacecraft are exposed to a hazardous micrometeoroid and orbital debris environment. These objects can collide at very high velocity, causing significant damage to operational satellites in any orbital regime, from low Earth orbit (LEO) to geosynchronous orbit (GEO). The optical measurement acquisition system consists of optic devices, including the telescope and the charge-coupled device (CCD), pointing devices, including computer and mount, image processing and astrometry algorithms, and accurate timing devices. The objects' TLEs are propagated to generate pointing commands to the mount so that the objects fall within the telescope field of view at the appropriate time. The satellite used to perform the residuals analysis and assess the OD procedure performance is SICRAL1 with the measurements collected during an observation campaign performed in October 2011. The OD is based on measurements equally spaced in time, at five-minute time intervals
Collision risk analysis for nanosatellite cluster launches
No full textNanospacecraft are usually launched in clusters from a single launch, in which they are hosted as secondary payloads. The nanospacecraft, e.g. CubeSats, are usually released simultaneously in small groups from one single container, in order to simplify the launcher interface manufacturing and the launch operations. The release sequence must be designed to minimize the risk of collisions between the nanospacecraft and the primary payload and the risk of impacts among the nanospacecraft themselves. Considering the increasing number of micro and nano-satellites in the recent space activity, establishing a methodology for the collision risk analysis and determining appropriate tools for release systems design is of interest. This paper describes the collision risk analysis for a nanosatellite cluster deployment, comparing results obtained with different release mechanisms, procedures and orbital dynamics modeling assumptions. The in orbit collision risk in the first orbits after launch depends on the orbital perturbations differential effects on the spacecraft trajectories and mostly on the in orbit injection initial conditions, such as release time delay among successive releases, relative initial position and velocity, which directly reflect on the satellite dispenser configuration, interface concept and mechanical parameters. The assumption is made that the spacecraft have no orbit control capabilities, therefore no collision avoidance maneuvers can be performed after the satellite release. The analytical model used for the analysis is based on the Encke equations for the relative motion, considering the main perturbations acting on the satellites, such as Earth gravitational field higher harmonics, Moon and Sun third body perturbations, solar radiation pressure, atmospheric drag. The risk of collisions is assessed performing Monte Carlo simulations based on the numerical integration of the equations of motion. The main variables of the simulations are the in orbit injection initial conditions, implemented in terms of release devices configuration and performances and including the effects on separation system faults or non nominal performance. The final results provide the collision risk assessment and the influence that the release devices configurations have on this risk. A case study is also described in detail, concerning the launch of a cluster of nine CubeSats in standard CubeSat dispensers and a heavier primary payload. Copyright ©2010 by the International Astronautical Federation. All rights reserved
Analysis of close approach in geo using optical measurements
No full textEarth orbiting spacecraft are exposed to hazardous Micrometeoroid and Orbital Debris environment. These objects can collide at very high velocity, causing significant damages to operational satellites in any orbital regime, from LEO to GEO. Many of these objects are catalogued and regularly monitored, thus their orbital parameters are always updated and can be used to perform a risk assessment analysis based on the probability of impact that can occur between orbiting objects. In order to perform a Close Approach (CA) analysis, the two space objects position and velocity vectors are necessary, as well as the state covariance. These parameters can be obtained from the Two Line Element sets (TLE); however the accuracy of the provided state vectors is not sufficient for accurate collision analyses, and further orbit determination should be performed in order to determine an accurate state vector and the related covariance. This level of accuracy can be achieved by integrating the TLE parameters with optical measures. Nevertheless, to achieve suitable orbit determination results from optical measurements the accuracy of the angular measures is as important as the timing precision: A tenth of a second error on timing can lead to several hundred meters error on the position estimation. In order to accomplish this requirement a Global Positioning System (GPS) receiver is used as external trigger for the CCD camera. In order to evaluate the measurement acquisition system performances the measures accuracy must be determined. To this purpose, several measurements of the Global Position System (GPS) satellites have been collected and compared to their precise ephemeris. About a hundred GPS satellite measures were used to achieve the statistical distributions of the error committed, both Along-Track and Cross-Track, in terms of mean and Standard Deviation (SD) values. Mean values achieved are on the order of magnitude of tenth of arcsecond for both cases, while SD are equal to 3.5 and 3.3 arcseconds for the Along-Track and the Cross-Track errors. In this paper is presented a study case, based on the Close Approach in GEO region between GORIZONT 11 and COSMOS 1738 occurred on 2011 December 22nd, to compare the results obtainable by using TLE only or the accurate orbit determination system based on the observation campaign. Copyright © (2012) by the International Astronautical Federation
Mesozoic extension controlling the Southern Alps thrust front geometry under the Po Plain, Italy: insights from sandbox models.
No full textIn the Southern Alps fold and thrust belt, east-west Mesozoic rifting controlled the development of extensional faults, the deposition of the sedimentary sequences and the thickness and distribution of the main detachment levels. Vertical and lateral heterogeneities strongly influenced the structural style of the subsequent north-south contractional phase, as revealed by surface mapping and by subsurface maps derived from seismic data. Along the strike of the chain, lateral terminations of thrust faults occur at syn-rift extensional faults, trending normal with respect to the contractional structures, From west to east, the thrust sheet number decreases and the order of structures and their wavelength changes. On a regional scale the effects produced by pre-existing heterogeneities on the development of contractional Alpine tectonic structures in the external area of the Southern Alps were evaluated by means of scaled sandbox analogue models. Modelled lateral heterogeneities produced different wavelength thrust sheets, salients and recesses, whereas vertical heterogeneities facilitated the development of structures of different orders. First-order structures detached at the base of the model and second-order structures detached at the intermediate relatively weak layers. Comparison of analogue model results with nature showed good geometrical similarities
GC-MS detection of chiral markers in cocoa beans of different quality and geographic origin
No full textErector spinae plane block for urgent pleuroscopy: a possible change in anesthetic approach for high-risk patients
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The effect of defruiting at different stages of fruit development on leaf photosynthesis of 'Golden Delicious' apple
No full textNet photosynthetic rates (A) of leaves on 11-year-old, field-grown apple trees (Malus domestica Borkh. cv. Golden Delicious) were measured after removal of fruits at four different stages of development. Defruiting decreased A by 21, 42, 27 and 7% when fruits were growing at 311, 293, 229 and 113 mg(DW) day(-1), respectively. Photosynthesis was inhibited more in the afternoon than in the morning, but it was not affected during the first 8 h after fruit removal. Inhibition of A was positively correlated with crop sink strength, but it was not correlated with fruit relative growth rate or crop load. Defruiting decreased A at saturating irradiances (PPFD > 1000 mu mol m(-2) s(-1)), but did not modify the apparent quantum yield of single leaves. These results suggest that the overall effect of defruiting on carbon fixation is negligible in dense canopies, but it may be significant in sparse canopies and in single shoots
Project management methodologies to improve standards development: the case of CEN TC 319 "Maintenance"
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