1,355,474 research outputs found
Rec. a: Dalla Preistoria all’Alto medioevo nell’Antico Cenedese, a cura di Giorgio Arnosti, Giovanni, Riviera e Fabrizio Schincariol, «Antichità Altoadriatiche» n. 89, Trieste, Editreg 2018, pp. 408, ill.
No full textRecensione agli Atti del Convegno per il 40° Fondazone del Gruppo Archeologico Cenedese
Interaction between slope flows and an urban heat Island
No full textThe local atmospheric circulation due to a city located at the bottom of a valley is reproduced by laboratory experiments analyzing the interaction between an urban heat island (UHI) and anabatic or katabatic slope flows. Slope flows are generated by the horizontal temperature difference between air adjacent to a mountain slope and the ambient air at the same altitude over the neighboring plane (or over the valley center). The thermal disomogeneity is a consequence of the daily heating due to the solar radiation and to the nightly cooling related to the infrared radiation emitted by the ground. Assuming clear sky and weak synoptic wind conditions, the slope flow is upslope (anabatic) during the daytime and downslope (katabatic) during the nighttime. The cool air settles down in the valley, starting the cold pool formation, a still and steady stratified environment. The slope flows present counter current compensating flows of lower velocity and larger thickness. The circulation associated to slope flows was studied in the past via field observations (Manins and Sawford, 1979; Hunt et al., 2003), analytical (Prandtl, 1952; Horst and Doran, 1983), numerical (Tripoli and Cotton, 1989) and experimental investigations (Fernando et al., 2000; Cenedese and Monti, 2004). Buoyancy-driven UHI circulation has been investigated in experimental and analytical study by Lu et al. (1997). The experiments described here are performed in a temperature controlled water-tank, the same employed by Cenedese and Monti (2003) and (2004) to investigate urban heat islands and sea-breeze flows, respectively
An Hidden Markov Model based transitional description of camera networks
No full textWe consider the problem of building a transitional model of an initially uncalibrated camera network. More specifically, we discuss a Hidden Markov Model (HMM) based strategy in which the model’s state-space is defined in terms of a partition of the physical network coverage. Transitions between any two such states are modeled by the distribution of the underlying Markov Process. Extending previous work in (Cenedese et al., 2010), we show how it is possible to infer the model structure and parameters from coordinate free observations and introduce a novel performance index that is used for model validation. We moreover show the predictive power of this HMM approach in simulated and real settings that comprise Pan-Tilt-Zoom (PTZ) cameras
Recognition of partially overlapped particle images using the Kohonen neural network
No full textA neural network is proposed for the recognition of partially overlapped particle images in the analysis of Particle Tracking Velocimetry (PTV) frames. The Kohonen neural network is an approximation to an optimum classifier. In this work it allows single particle images to be distinguished from overlapped particle images by shape analysis: it classifies 99.1% of the spots correctly (in test images). If a spot has an almost circular shape, the barycenter co-ordinates are extracted. If the spot shape is far from being circular, it is believed to be a particle overlap, and a procedure to find more centroids is activated. The particle recognizer based on the Kohonen neural network is tested on both multi-exposed and single-exposure images at high particle density, and compared to a particle recognizer that did not consider the partial overlap. The management of overlapped particles causes the neural network to produce a big improvement in the number of barycenters that can be extracted from these images. The practical consequence is that the seeding density in PTV can be increased, so as to improve the spatial resolution of the technique in the velocity field calculation. © 1995 Springer-Verlag
Quaternion-based non-singular terminal sliding mode control for a satellite-mounted space manipulator
No full textIn this paper, a robust control solution for a satellite equipped with a
robotic manipulator is presented. First, the dynamic model of the system is
derived based on quaternions to describe the evolution of the attitude of the
base satellite. Then, a non-singular terminal sliding mode controller that
employs quaternions for attitude control, is proposed for concurrently handling
all the degrees of freedom of the space manipulator. Moreover, an additional
adaptive term is embedded in the controller to estimate the upper bounds of
disturbances and uncertainties. The result is a resilient solution able to
withstand unmodelled dynamics and interactions. Lyapunov theory is used to
prove the stability of the controller and numerical simulations allow assessing
performance and fuel efficiency.Comment: New figures and some text clarification
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