323,955 research outputs found
Scheda n°4. Matematica Attuariale
No full textLa scheda, eseguita nell'ambito delle attività del SEMINARIO DIDATTICO della Facoltà di Scienze M. F. N. dell'Università di Genova e finalizzata all'uso nella scuola superiore, propone un approccio storico alla statistica e alla matematica attuariale attraverso l'utilizzo di testi originali di A. De Moivre
Inverse Radon transform scaling via spin rate estimation for resident space object size assessment
No full textThe population of resident space objects (RSOs) has increased drastically during the past years. These objects became a great threat for active satellites. The consequences of a collision with orbital debris strictly depend on the size and velocity of the debris. Typical collision velocities range from seven to fifteen kilometres per second, depending on the collision angle. Such debris must be detected, tracked, and catalogued in order to avoid collisions. Here, object size-related parameters will be estimated by making use of a scaled inverse Radon transform (IRT). The scaled IRT is obtained by estimating the object spin rate
A comparison of radon domain approaches for resident space object's parameter estimation
No full textThe amount of space debris orbiting around the Earth has seen a dramatic growth through the recent years. This growth is fed by an avalanche multiplication process. In fact, according to the 'Kessler syndrome', any collision generates more debris that then collide with other objects and produce further debris. This growth represents a serious hazard for operational spacecraft, human activities in space and even the Earth environment since their re-enter is uncontrolled. Thus, it is important to continuously monitor and characterize them. Instrumental features for their characterization are surely represented by their size and spin rate. The Inverse Radon transform (IRT) tool has been proved to be a valid solution for this task. In this paper, we propose a comparison study between different approaches based on IRT for the estimation of the object's rotation period
The Importance of Local and Global Externalities for the Urban Industriai Development. A Dynamic Factor Analysis
No full textThe importance of local and global externalities for the urban industrial develpment. A dynamic factor analysis
No full textSize estimation of space debris models from their RCS measured in anechoic chamber
No full textSpace debris characterization is becoming increasingly important in the framework of Space Situational Awarenees (SSA). In fact, the uncontrolled multiplication of orbital debris has been statistically quantified around 130 million objects. It is therefore instrumental to take actions to protect operational spacecraft and human activities in space. Since years, NASA has been working to this end and has developed an RCS-to-size mapping function, known as Size Estimation Model (SEM). In this paper, RCS data acquired during a measurement campaign in an anechoic chamber has been used to derive a similar function. A comparison of the size estimated by using both models is shown in this paper
A learning machine for resource-limited adaptive hardware
No full textMachine learning algorithms allow to create highly adaptable systems, since their functionality only depends on the features of the inputs and the coefficients found during the training stage. In this paper, we present a method for building support vector machines (SVM), characterized by integer parameters and coefficients. This method is useful to implement a pattern recognition system on resource-limited hardware, where a floating-point unit is often unavailable
Freeze drying of pharmaceutical excipients close to collapse temperature: Influence of the process conditions on process time and product quality
No full textDrone-based 3D interferometric ISAR Imaging
No full textThree-dimensional (3D) radar imaging of non-cooperative targets has become very attractive as it significantly improves the more traditional two-dimensional radar imaging technology. Drone-based radar systems, on the other end, offer a very flexible, easily deployable and low-cost solution for airborne radar imaging applications. This paper introduces the concept of drone-based 3D radar imaging via an interferometric/ISAR imaging approach. The theoretical work presented in this paper sets the ground for this new technology and simulation results provide some example of the ability of this system to provide 3D radar images of surface moving targets when imaged by a set of drones
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