1,721,104 research outputs found

    Analisi in frequenza con il metodo della massima entropia

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    Allo scopo di superare alcuni dei problemi (numero dei dati carnipona ti, risoluzione in frequenza. necessita di zoom) che si presenlano con i metodi di analisi tradizionale e. in partieolare per riconoscere componenti con frequenze molto vicine tra di loro presenti in un segna!e con rumore e state irnplementato un programma di calcolo che permette I' anatisi in frequenza di segnali con un' elevata risoluzione e necessita di un numero di dati carnplonati inferiore rispetto ai metodi tradizionali. Tra Ie varie pos sibilita offerte dagli algoritmi di analisi sviluppati negli ultimi anni si e scelto il metodo delia rnassima entropia (MEM 0 MESA) [4,6,7,15.18,19] e sl e voluto controllare se eifettivamente tale melodo eonsente una risoluzione piu spinta rispetto ai melodi lradizionali e se permette di utilizz are un numero di dati inferiore[22]

    Diagnostic Procedure for two stage light gas gun pellet injector

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    This work, by means of the numerical modeling of a two-stage light gas gun, analyses deterioration parameters and proposes a procedure for diagnosing functional parameters of two-stage light gas guns with high firing frequency. Analyzed parameters are: piston wear and deformation, delay in first-stage valve opening, and piston seize-up. The procedure was developed by means of gas-dynamic numerical modeling. Experimental tests demonstrate that this procedure can be realistically applie

    Reliability oriented design and testing of a telescope's front cover for long life space mission

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    The reliability of a telescope's front cover constitutes its primary demand, not to compromise the functionality of the whole instrument. From this point of view the design of the mechanism and the testing campaign should prove its fulfillment to the performance requirements, and its insensitivity to the environmental conditions, particularly for a long life mission where the performances have to be guaranteed along the whole life of the experiment. The Front Door Mechanism for the WAC (Wide Angle Camera) and NAC (Narrow angle Camera) telescopes constituting the OSIRIS experiment of the ROSETTA mission has been optimized to minimize the loads acting during its functional phases and the loads transferred to the other components of the optical bench, but at the same time to bear the loads acting during the launch and in the operating environment. The test campaign performed to demonstrate the compliancy of the mechanism to the requirements included environmental tests such as vibration and thermal vacuum cycling, life test, measurement of the resistant torque and of the reliability of the housekeeping sensors, and proved the fulfillment of the device to the requirements in terms of performances and insensitivity to the environmental tests performed. The life test executed during the thermal cycling proved the capacity of the mechanism to maintain its characteristics all along the number of activations foreseen for the test, being also unaffected by the temperature variations within the operating range
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