54,392 research outputs found
GNSS-R altimeter performance: analysis of Cramer-Rao lower bounds
No full textEarth-reflected Global Navigation Satellite Systemsignals
have become an attractive tool for remote sensing, being
proposed as a means to perform ocean altimetry, among many
other applications. The technique exploiting navigation signals is
widely known as GNSS-R. In this paper the well-known Cramer-
Rao lower bound is used to predict the sea surface height
estimation precision of a GNSS-R based spaceborne altimeter,
exploiting the open-access GPS L1 C/A code signal. Real
spaceborne data acquired by the GPS-R receiver on-board UKDMC
satellite is used to extract statistical properties of
spaceborne GPS reflected signals.Peer ReviewedPostprint (published version
A Fisher-Rao metric for paracatadioptric images of lines
No full textIn a central paracatadioptric imaging system a perspective camera takes an image of a scene reflected in a paraboloidal mirror. A 360° field of view is obtained, but
the image is severely distorted. In particular, straight lines in the scene project to circles in the image. These distortions make it diffcult to detect projected lines using standard image processing algorithms. The distortions are removed using a Fisher-Rao metric which is defined on the space of projected lines in the paracatadioptric image. The space of projected lines is divided into subsets such that on each subset the Fisher-Rao metric is closely approximated by the Euclidean metric. Each subset is sampled at the vertices of a square grid and values are assigned to the sampled points using an adaptation of the trace transform. The result is a set of digital images to which standard image processing algorithms can be applied.
The effectiveness of this approach to line detection is illustrated using two algorithms, both of which are based on the Sobel edge operator. The task of line detection is reduced to the task of finding isolated peaks in a Sobel image. An experimental comparison is made between these two algorithms and third algorithm taken from the literature and
based on the Hough transform
Narayanella, a new name for Narayana Subba Rao (hymenoptera : mymaridae)
No full textThe name Narayana was applied (Subba Rao, 1976) to a genus erected for the new species N. pilipes reared from the gaUs of Lagerstoemia flos reginae. Unfortunately the author overlooked the vulid and prior use of Narayana by Distant (1908). Narayana Distant was erected with rusticitatus as type-species (Issidae: Homoptera). Hence Narayana Subba Rao is a junior homonym which has to be replaced according to the rules of the International Zoological Nomenclature
Reply to " Comments on Capture and Retransmission Control in Mobile Radio"
No full textThe present paper replies to a comment by Nguyen et al. (IEEE Trans. Sel. Areas Commun., vol.24, no.12, p.2340-1, December 2006) on the original paper by Zorzi and Rao (IEEE Trans. Sel. Areas Commun., vol.12, no.8, p.1289-98, October 1994
Application of the Fisher-Rao metric to ellipse detection
No full textThe parameter space for the ellipses in a two dimensional image is a five dimensional manifold, where each point of the manifold corresponds to an ellipse in the image. The parameter space becomes a Riemannian manifold under a Fisher-Rao metric, which is derived from a Gaussian model for the blurring of ellipses in the image. Two points in the parameter space are close together under the Fisher-Rao metric if the corresponding ellipses are close together in the image. The Fisher-Rao metric is accurately approximated by a simpler metric under the assumption that the blurring is small compared with the sizes of the ellipses under consideration. It is shown that the parameter space for the ellipses in the image has a finite volume under the approximation to the Fisher-Rao metric. As a consequence the parameter space can be replaced, for the purpose of ellipse detection, by a finite set of points sampled from it. An efficient algorithm for sampling the parameter space is described. The algorithm uses the fact that the approximating metric is flat, and therefore locally Euclidean, on each three dimensional family of ellipses with a fixed orientation and a fixed eccentricity. Once the sample points have been obtained, ellipses are detected in a given image by checking each sample point in turn to see if the corresponding ellipse is supported by the nearby image pixel values. The resulting algorithm for ellipse detection is implemented. A multiresolution version of the algorithm is also implemented. The experimental results suggest that ellipses can be reliably detected in a given low resolution image and that the number of false detections
can be reduced using the multiresolution algorithm
P. R. Ramachandra Rao, Andhra Sculpture
No full textRegnier Rita H. P. R. Ramachandra Rao, Andhra Sculpture . In: Arts asiatiques, tome 42, 1987. pp. 121-122
P. R. Ramachandra Rao, Contemporary Indian Art
No full textFilliozat Jean. P. R. Ramachandra Rao, Contemporary Indian Art. In: Arts asiatiques, tome 25, 1972. p. 207
Introduzione
No full textI palazzi comunali costituiscono una delle impronte più significative lasciate dai grandi comuni cittadini, soprattutto in Lombardia, Emilia e Toscana. Con tratti tipologici ben riconoscibili (per esempio il grande spazio aperto al pianterreno oppure la torre) hanno avuto un impatto monumentale sui centri delle città comunali, oggetto di rinnovamenti e restauri nel corso dei secoli. Ma cosa succede in quelle aree dove i comuni ebbero una vita più discontinua? Esistono i palazzi comunali ai margini del mondo comunale e, se sì, quali forme assumono? Questo è il tema di ricerca affrontato dal volume, che offre uno sguardo ampio sui palazzi comunali nel mondo mediterraneo, dalle Alpi, all’Italia meridionale, fino alla Croazia, alla Corsica e alla Provenza
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