IRIS Pol. Torinohttps://iris.polito.itIl sistema di repository digitale IRIS acquisisce, archivia, indicizza, conserva e rende accessibili prodotti digitali della ricerca.Mon, 25 Jan 2021 08:40:58 GMT2021-01-25T08:40:58Z101061Optimal Geometry of Self-Field Magnetoplasmadynamic Thrustershttp://hdl.handle.net/11583/1409114Titolo: Optimal Geometry of Self-Field Magnetoplasmadynamic Thrusters
Thu, 01 Jan 1998 00:00:00 GMThttp://hdl.handle.net/11583/14091141998-01-01T00:00:00ZOptimal Performance of a Dual-Fuel Single-Stage Rockethttp://hdl.handle.net/11583/1398244Titolo: Optimal Performance of a Dual-Fuel Single-Stage Rocket
Thu, 01 Jan 1998 00:00:00 GMThttp://hdl.handle.net/11583/13982441998-01-01T00:00:00ZMars gravity assist to improve missions towards main-belt asteroidshttp://hdl.handle.net/11583/1398231Titolo: Mars gravity assist to improve missions towards main-belt asteroids
Abstract: An indirect optimization method is applied to find rendezvous trajectories to reach asteroids of the main belt using solar electric propulsion. Direct trajectories and missions that receive gravity assist from Man en route to the target are presented and compared in terms of final mass. Numerical results prove that missions with gravity assist surely perform better, if the trip tune exceeds five years. Faster flyby missions are superior to direct trajectories if simple guidelines concerning the asteroid's orbital parameters are used to select the target and to take the greatest benefit from the Mars gravity assist. A direct mission can be carried out with a similar performance at time intervals which correspond to the Earth/asteroid synodic period. Gravity assist missions require the correct angular phasing of the three relevant bodies and mission opportunities are less frequent, a shortcoming which is overwhelmed by the large number of potential targets. Actual mission opportunities for a rendezvous in the next decade are found and presented for a small number of interesting asteroids.
Wed, 01 Jan 2003 00:00:00 GMThttp://hdl.handle.net/11583/13982312003-01-01T00:00:00ZMinimum-Fuel Escape from Two-Body Sun-Earth Systemhttp://hdl.handle.net/11583/1398236Titolo: Minimum-Fuel Escape from Two-Body Sun-Earth System
Abstract: Escaping from the solar system by receiving gravity assist from the Earth is considered in this paper. A simple procedure, which neglects the eccentricity of the Earth's orbit and uses the two-body problem equations and the patched-conic approximation, provides near-optimal trajectories using either a single or multiple Earth flybys. The analysis shows that the amount of propellant required to escape from the solar system decreases with the number of flybys, but the mission time increases. The same approach is also used to find near-optimal trajectories that use a single powered flyby. The eccentricity of the Earth's orbit can be exploited to reduce the characteristic velocity; an indirect optimization procedure provides the most favorable locations where the Earth should be intercepted.
Fri, 01 Jan 1999 00:00:00 GMThttp://hdl.handle.net/11583/13982361999-01-01T00:00:00ZHeat Transfer Analysis in Pressurizer Tank Under Microgravityhttp://hdl.handle.net/11583/1398251Titolo: Heat Transfer Analysis in Pressurizer Tank Under Microgravity
Wed, 01 Jan 1986 00:00:00 GMThttp://hdl.handle.net/11583/13982511986-01-01T00:00:00ZTraiettorie ottimali di ascesa in orbitahttp://hdl.handle.net/11583/1409142Titolo: Traiettorie ottimali di ascesa in orbita
Fri, 01 Jan 1993 00:00:00 GMThttp://hdl.handle.net/11583/14091421993-01-01T00:00:00ZDeployment of a Two-Spacecraft Formation into a Highly Elliptic Orbit with Collision Avoidancehttp://hdl.handle.net/11583/2503132Titolo: Deployment of a Two-Spacecraft Formation into a Highly Elliptic Orbit with Collision Avoidance
Abstract: The finite-thrust deployment of a two-satellite formation into a highly elliptic orbit is optimized by means of an indirect approach, which is based on the theory of optimal control. Earth oblateness and gravitational perturbations from Moon and Sun are considered. The optimization procedure provides the engine switching times and the thrust direction during each burn in order to transfer the satellites to the same prescribed final orbit with assigned distance between them at the apogee passage; the total final mass is maximized. A minimum-distance constraint is introduced when required to avoid collision risk. Different deployment strategies are analyzed; in particular, the classical chaser-target approach is compared to cooperative deployment. Necessary conditions for optimality are derived and numerical results presented.
Sun, 01 Jan 2012 00:00:00 GMThttp://hdl.handle.net/11583/25031322012-01-01T00:00:00ZNozzle Effects on Linear Stability Behaviour of Combustorshttp://hdl.handle.net/11583/1409140Titolo: Nozzle Effects on Linear Stability Behaviour of Combustors
Fri, 01 Jan 1993 00:00:00 GMThttp://hdl.handle.net/11583/14091401993-01-01T00:00:00ZIndirect Methods for the Optimization of Spacecraft Trajectorieshttp://hdl.handle.net/11583/2503592Titolo: Indirect Methods for the Optimization of Spacecraft Trajectories
Abstract: In this chapter, a general methodology to apply the theory of optimal control to spacecraft trajectories is outlined. This peculiar procedure allows for an almost mechanical derivation of the boundary conditions which must be satisfied by an optimal trajectory, depending on the specific constraints of the problem under analysis. The general way of posing the optimal control problem makes this indirect approach suitable to
manage many specific features of the space missions, such as, impulsive and/or low-thrust engines, planetary flybys, atmospheric flight, and so on. Peculiarities of the problem simply modify the set of differential equations and boundary conditions, in the context of the same theoretical frame. Examples will show that the indirect approach can deal efficiently with complex problems of space trajectory optimization. As in the case of direct methods, the indirect approach requires a tentative solution and convergence to the optimum is typically obtained if the tentative solution is sufficiently close to the optimal one. Suitable procedures to find tentative guesses for the considered problems are described.
Sun, 01 Jan 2012 00:00:00 GMThttp://hdl.handle.net/11583/25035922012-01-01T00:00:00ZNumerical Investigations on the Generation and Development of Rotating Stallshttp://hdl.handle.net/11583/1409122Titolo: Numerical Investigations on the Generation and Development of Rotating Stalls
Sun, 01 Jan 1978 00:00:00 GMThttp://hdl.handle.net/11583/14091221978-01-01T00:00:00Z