Spacecraft dynamics under the action of Y-dot magnetic control law

The paper investigates the dynamic behavior of a spacecraft when a single magnetic torque-rod is used for achieving a pure spin condition by means of the so-called Y-dot control law. Global asymptotic convergence to a pure spin condition is proven on analytical grounds when the dipole moment is proportional to the rate of variation of the component of the magnetic field along the desired spin axis. Convergence of the spin axis towards the orbit normal is then explained by estimating the average magnetic control torque over one orbit. The validity of the analytical results, based on some simplifying assumptions and approximations, is finally investigated by means of numerical simulation for a fully non-linear attitude dynamic model, featuring a tilted dipole model for Earth׳s magnetic field. The analysis aims to support, in the framework of a sound mathematical basis, the development of effective control laws in realistic mission scenarios. Results are presented and discussed for relevant test cases

Identification from Flight Data of the Aerodynamics of an Experimental Re-Entry Vehicle

Post flight data analyses are essential activities in aerospace projects. In particular, there is a specific interest in obtaining vehicle aerodynamic characteristics from flight data, especially for re-entry vehicle, in order to better understand theoretical predictions, to validate wind- tunnel test results and to get more accurate and reliable mathematical models for the purpose of simulation, stability analysis, and control system design and evaluation. Indeed, due to atmospheric re-entry specificity in terms of environment and phenomena, ground based experiments are not fully exhaustive and in-flight experimentation is mandatory. Moreover pre-flight models are usually characterised by wide uncertainty ranges, which should be reduced. These objectives can be reached by performing vehicle’s model identification from flight data

Seismic noise cross-correlation in the urban area of Benevento city (Southern Italy)

This article has been accepted for publication in Geophysical Journal International ©: The Authors 2019. Published by Oxford University Press on behalf of the Royal Astronomical Society. All rights reserved. Uploaded in accordance with the publisher's self-archiving policy.In the last decade the use of passive methods has become appealing in reconstructing the properties of the propagation medium by seismic ambient noise data, without the use of localized natural or artificial sources. A temporary seismic network was installed in the urban area of Benevento (southern Italy) in order to characterize the shallow structure of the city using stable methods for the analysis of the seismic noise continuously acquired by stations. The city of Benevento is one of the italian areas with highest seismic hazard, and at present the region is affected by low energy swarms and sparse events (Ml ≤ 4.1). It has been struck by several destructive historical earthquakes, the strongest of which occurred in 1456, 1688, 1805 with associated MCS intensity up to X–XI. We used the sixteen seismic stations installed in Benevento to record ambient noise for about 1 month. The stations were equipped with different seismic instruments: (i) digitizers Quanterra Q330 connected to Le3d-5 s short-period sensors; (ii) Nanometrics Centaur digitizers coupled with Trillium Compact 120s broad-band velocimeters; (iii) one station with Episensor force balance accelerometer connected to a D6BB-DIN Staneo digitizer. Interstations Green's functions were reconstructed by the cross-correlation of continuous ambient noise data, and surface waves signals were extracted from Green's Functions (GFs) for investigating the elastic properties of the subsurface structure. In this regard, we performed the beamforming analysis to test the hypothesis of isotropy distribution of noise sources on which the cross-correlation method is based, and the particle motion analysis to confirm the presence of surface Rayleigh waves in the GFs. We analysed the temporal stability of the cross-correlated signals and the results show that 2 weeks of continuous measurements are sufficient to stabilize the surface waves signal extracted from the GFs. The phase velocity dispersion curves are computed for 115 station pairs through the use of a far-field representation of the surface-wave GFs and an image transformation technique. Our strategy based on cross-correlation analysis provides robust phase-velocity dispersion curves that vary approximately from 1.4 km s–1 at 0.7 Hz to 0.6 km s–1 at 5 Hz. Different pairs were selected for the inversion of phase-velocity dispersion curves aimed to derive 1-D shear-wave velocity (Vs) profiles (up to a maximum depth of about 500 m) representative of some areas of the city characterized by different soil deposits.Published1524–15425T. Sismologia, geofisica e geologia per l'ingegneria sismicaJCR Journa

Disease-relevant proteostasis regulation of cystic fibrosis transmembrane conductance regulator

Mismanaged protein trafficking by the proteostasis network contributes to several conformational diseases, including cystic fibrosis, the most frequent lethal inherited disease in Caucasians. Proteostasis regulators, as cystamine, enable the beneficial action of cystic fibrosis transmembrane conductance regulator (CFTR) potentiators in \u394F508-CFTR airways beyond drug washout. Here we tested the hypothesis that functional CFTR protein can sustain its own plasma membrane (PM) stability. Depletion or inhibition of wild-type CFTR present in bronchial epithelial cells reduced the availability of the small GTPase Rab5 by causing Rab5 sequestration within the detergent-insoluble protein fraction together with its accumulation in aggresomes. CFTR depletion decreased the recruitment of the Rab5 effector early endosome antigen 1 to endosomes, thus reducing the local generation of phosphatidylinositol-3-phosphate. This diverts recycling of surface proteins, including transferrin receptor and CFTR itself. Inhibiting CFTR function also resulted in its ubiquitination and interaction with SQSTM1/p62 at the PM, favoring its disposal. Addition of cystamine prevented the recycling defect of CFTR by enhancing BECN1 expression and reducing SQSTM1 accumulation. Our results unravel an unexpected link between CFTR protein and function, the latter regulating the levels of CFTR surface expression in a positive feed-forward loop, and highlight CFTR as a pivot of proteostasis in bronchial epithelial cells