Analytical Approach Validation for the Spin-Stabilized Satellite Attitude

An analytical approach for spin-stabilized spacecraft attitude prediction is presented for the influence of the residual magnetic torques and the satellite in an elliptical orbit. Assuming a quadripole model for the Earth s magnetic field, an analytical averaging method is applied to obtain the mean residual torque in every orbital period. The orbit mean anomaly is used to compute the average components of residual torque in the spacecraft body frame reference system. The theory is developed for time variations in the orbital elements, giving rise to many curvature integrals. It is observed that the residual magnetic torque does not have component along the spin axis. The inclusion of this torque on the rotational motion differential equations of a spin stabilized spacecraft yields conditions to derive an analytical solution. The solution shows that the residual torque does not affect the spin velocity magnitude, contributing only for the precession and the drift of the spin axis of the spacecraft. The theory developed has been applied to the Brazilian s spin stabilized satellites, which are quite appropriated for verification and comparison of the theory with the data generated and processed by the Satellite Control Center of Brazil National Research Institute. The results show the period that the analytical solution can be used to the attitude propagation, within the dispersion range of the attitude determination system performance of Satellite Control Center of Brazil National Research Institute

LA FINANZA PUBBLICA ITALIANA. RAPPORTO 2004

Nella prima sezione di questa edizione 2004 del Rapporto di finanza pubblica, al monitoraggio dei temi tradizionali del rapporto – conti pubblici, fisco, previdenza, assistenza, sanità, federalismo fiscale, servizi di pubblica utilità – si affianca un approfondimento relativo al finanziamento dell’università.I cinque contributi della seconda sezione sono poi dedicati ad un unico tema, di particolare rilevanza nel dibattito in corso: gli effetti dell’immigrazione sulla finanza pubblica

LA FINANZA PUBBLICA ITALIANA. RAPPORTO 2003

La prima sezione del Rapporto analizza l\u2019andamento delle politiche pubbliche nel campo della tassazione, del welfare, della sanit\ue0, del federalismo e dei servizi di pubblica utilit\ue0 duran-te il 2002. Stretto tra una congiuntura sfavorevole e la promessa di riduzioni delle imposte, il governo si \ue8 dibattuto tra una sostanziale inerzia nello sforzo riformista e la moltiplicazione di misure unicamente volte a contenere il peggioramento dei conti pubblici.La seconda sezione affronta due temi di particolare rilevanza nel dibattito corrente. 1.Il fi-nanziamento, con la partecipazione dei privati, delle infrastrutture produttive e la gestione e alienazione del patrimonio immobiliare. Particolare attenzione \ue8 posta all\u2019esperienza delle car-tolarizzazioni sia a livello nazionale (operazioni Scip1 e Scip2) che internazionale. 2.La long term care. Il nostro paese appare in ritardo nella predisposizione di adeguate strategie di rispo-sta alla prevedibile crescita della domanda di servizi assistenziali a favore degli anziani non au-tosufficienti Viene in particolare valutata criticamente l'opportunit\ue0 di creare un apposito Fon-do per il finanziamento delle prestazioni quale programma autonomo del sistema di welfar

Semi-analytical study of the rotational motion stability of artificial satellites using quaternions

This study at aims performing the stability analysis of the rotational motion to artificial satellites using quaternions to describe the satellite attitude (orientation on the space). In the system of rotational motion equations, which is composed by four kinematic equations of the quaternions and by the three Euler equations in terms of the rotational spin components. The influence of the gravity gradient and the direct solar radiation pressure torques have been considered. Equilibrium points were obtained through numerical simulations using the softwares Matlab and Octave, which are then analyzed by the Routh-Hurwitz Stability Criterion

Unscented Kalman Filter Applied to the Spacecraft Attitude Estimation with Euler Angles

The aim of this work is to test an algorithm to estimate, in real time, the attitude of an artificial satellite using real data supplied by attitude sensors that are on board of the CBERS-2 satellite (China Brazil Earth Resources Satellite). The real-time estimator used in this work for attitude determination is the Unscented Kalman Filter. This filter is a new alternative to the extended Kalman filter usually applied to the estimation and control problems of attitude and orbit. This algorithm is capable of carrying out estimation of the states of nonlinear systems, without the necessity of linearization of the nonlinear functions present in the model. This estimation is possible due to a transformation that generates a set of vectors that, suffering a nonlinear transformation, preserves the same mean and covariance of the random variables before the transformation. The performance will be evaluated and analyzed through the comparison between the Unscented Kalman filter and the extended Kalman filter results, by using real onboard data

Safety fences and barriers

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Spectroscopic studies of alkali vapours in intense laser fields

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