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2002 Journal article Restricted

All-sky astrophysical component separation with fast independent
Maino D., Farusi A., Baccigalupi C., Perrotta F., Banday A. J., Bedini L., Burigana C., De Zotti G., Gorski K. M., Salerno E.
We present a new, fast, algorithm for the separation of astrophysical components superposed in maps of the sky. The algorithm, based on the Independent Component Analysis (ICA) technique, is aimed at recovering both the spatial pattern and the frequency scalings of the emissions from statistically independent astrophysical processes, present along the line-of-sight, from multi-frequency observations, without any a priori assumption on properties of the components to be separated, except that all of them, except possibly one, must have non-Gaussian distributions. The analysis starts from very simple toy-models of the sky emission in order to assess the quality of the reconstruction when inputs are well known and controlled. In particular, we study the dependence of the results of separation conducted on and off the Galactic plane independently, showing that optimal separation is achieved for sky regions where components are smoothly distributed. Then we consider simulated observations of the microwave sky with angular resolution and instrumental noise, supposed to be white and stationary, at the mean nominal levels for the Planck satellite. The angular response function is assumed to be identical at each frequency since this is, up to now, one of the Fast Independent Component Analysis (FASTICA) limitations. We consider several Planck observation channels containing the most important known diffuse signals: the cosmic microwave background (CMB), Galactic synchrotron, dust and free–free emissions. A method for calibrating the reconstructed maps of each component at each frequency has been devised. The spatial patterns of all the components have been recovered on all scales probed by the instrument. In particular, the CMB angular power spectra is recovered at the per cent level up to l_max = 2000. Frequency scalings and normalization have been recovered with better than 1 per cent precision for all the components at frequencies and in sky regions where their signal-to-noise ratio >1.5; the error increases at 10 per cent level for signal-to-noise ratios =1. Runs have been performed on a Pentium III 600-MHz computer; although the computing time slightly depends on the number of channels and components to be recovered, FASTICA typically took about 10 min for all-sky simulations with 3.5-arcmin pixel size. Although the quoted results have been obtained under a number of simplifying assumptions, we conclude that FASTICA is an extremely promising technique for analysing the maps that will be obtained by the forthcoming high-resolution CMB experiments.Source: Monthly notices of the Royal Astronomical Society (Print) 334 (2002): 53–68.

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2002 Journal article Restricted

An automatic method for the recognition and classification of the A-phases of the cyclic alternating pattern
Navona C., Barcaro U., Bonanni E., Di Martino F., Maestri M., Murri L.
Objective: The aim of the research has been to introduce an automatic method, simple from the mathematical and computational points of view, for the recognition and classification of the A-phases of the Cyclic Alternating Pattern. Method: The automatic method was based on the computation of five descriptors, which were derived from the EEG signal and were able to provide a meaningful data reduction. Each of them corresponded to a different frequency band. Results: The computation of these descriptors, followed by the introduction of two suitable thresholds and of simple criteria for logical discrimination, provided results with were in good agreement with those obtained with visual analysis. The method was versatile and could be applied to the study of other important microstructure phenomena by means of very small adaptations. Conclusions: The simplicity of the method lead to a better understanding and a more precise definition of the visual criteria for the recognition and classification of the microstructure phenomena.Source: Clinical neurophysiology 113 (2002): 1826–1831.

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2002 Journal article Restricted

Computational complexity analysis of a 3D neural network approach to volume matching
Di Bona S., Niemann H., Salvetti O., Wolf M.
Automatic registration of digital images is an important support in the medical field for physicians and surgeons. In fact, comparison of anatomical scan is a fundamental procedure for disease prediction, lesions quantification or for evaluating the results of a therapy. A new proposed approach implements three-dimensional neural networks to match, and hence to register, volumetric data sets of the brain in order to evaluate the differences between two volumes. The high computational complexity of this approach has been improved by implementing a more efficient method to train the networks.Source: Pattern recognition 12 (2002): 63–69.

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2002 Journal article Restricted

Degradation identification and model parameter estimation in discontinuity-adaptive visual reconstruction
Tonazzini A., Bedini L.
This paper describes our recent experiences and progress towards an efficient solution of the highly ill-posed and computationally demanding problem of blind and unsupervised visual reconstruction. Our case study is image restoration, i.e. deblurring and denoising. The methodology employed makes reference to edge-preserving regularization. This is formulated both in a fully Bayesian framework, using a MRF image model with explicit, and possibly geometrically constrained, line processes, and in a deterministic framework, where the line process is addressed in an implicit manner, by using a particular MRF model which allows for self-interactions of the line and an adaptive variation of the model parameters. These MRF models have been proven to be efficient in modeling the local regularity properties of most real scenes, as well as the local regularity of object boundaries and intensity discontinuities.In both cases, our approach to this problem attempts to effectively exploit the correlation between intensities and lines, and is based on the assumption that the line process alone, when correctly recovered and located, can retain a good deal of information about both the hyperparameters that best model the whole image and the degradation features. We show that these approaches offer a way to improve both the quality of the reconstructed image, and also the estimates of the degradation and model parameters, and significantly reduce the computational burden of the estimation processes.Source: Advances in imaging and electron physics 120 (2002): 193–284. doi:10.1016/S1076-5670(02)80036-2
DOI: 10.1016/s1076-5670(02)80036-2

See at: academic.microsoft.com Restricted | www.sciencedirect.com Restricted | www.sciencedirect.com Restricted | biblioproxy.cnr.it | CNR ExploRA


2002 Journal article Restricted

Diving behaviour differs between incubating and brooding Brunnich's guillemoth's, Uria lomvia
Benvenuti S., Dall'Antonia S., Falk K.
Bird-borne data loggers were used to investigate the foraging strategies of Brünnich's guillemots breeding in a colony in the North Water Polynya: the flight performance and diving activity of incubating birds were compared to those of chick-rearing individuals. No significant differences were recorded between the bird groups in the potential foraging range. Conversely, clear differences were revealed between incubating and chick-rearing birds in diving behaviour. Chick-rearing birds were generally foraging at a significantly greater depth, and spent significantly higher proportions of the time submerged, than brooding individuals. Despite these differences, the estimated average daily energy expenditure of chick-rearing Brünnich's guillemots was only about 6% higher than that during incubation.Source: Polar biology (Print) 25 (2002): 474–478. doi:10.1007/s00300-002-0372-0
DOI: 10.1007/s00300-002-0372-0

See at: Polar Biology Restricted | Polar Biology Restricted | Polar Biology Restricted | Polar Biology Restricted | Polar Biology Restricted | CNR ExploRA Restricted | www.scopus.com Restricted


2002 Journal article Open Access OPEN

Foraging behaviour of thick-billed murres breeding in different sectors of the North Water polynya: an intercolony comparison
Falk K., Benvenuti S ., Dall'Antonia L., Gilchrist G., Kampp K.
The North Water polynya is an area of open water that occurs year round between northwest Greenland and Canada. Oceanographic conditions differ between the western ('latent heat' polynya type) and extreme eastern ('sensible heat' polynya type) sectors of the polynya, and the effects of this variation on prey availability and foraging conditions for high trophic-level predators are unknown. Thick-billed murres Uria lomvia breed on both sides of the polynya, and we conducted inter-colony comparisons of their foraging ecology. We measured time allocation and foraging efforts of chick-rearing adults using electronic data-loggers which recorded dive profiles and flight activity. Murres on the western side of the North Water polynya foraged at relatively shallow depths and rarely (4.4% of dives) explored depths beyond 70 m. In contrast, murres on the eastern side searched for prey at >70 m in 23% of all dives, and spent a greater share of each trip actively diving. The Canadian birds made foraging trips of longer duration than the Greenland murres, but they also spent more time 'resting' at the sea surface. Rest time at sea was apparently the only time buffer available for increasing foraging effort. The Greenland birds had little room for increasing foraging effort, while the Canadian birds had spare capacity for additional work. Maximum potential foraging ranges were equal at the 2 colonies (75% within 50 km), and the murres had access to approximately equally-sized areas of open sea. We estimate that the density of foraging birds at sea within the 50 km of colonies would be 6.5 times higher on the Canadian side due to the large breeding colony at Coburg Island. Intra-specific competition for food should increase with increasing colony size because the predators may reduce food resources within their foraging range. Nevertheless, the Canadian birds worked less than Greenland murres, indicating a relatively good food availability in the western part of the polynya. However, the higher foraging effort by Greenland murres paid off in a higher chick growth rate, so it remains unclear why the Canadian birds did not also make use of their spare capacity to increase foraging effort. Since high-level zooplankton/fish stock interactions are seldom part of oceanographic studies in the Arctic, seabird foraging behaviour and breeding ecology serve as two of the few indicators of possible local variation within the polynya ecosystem.Source: Marine ecology. Progress series (Halstenbek) 231 (2002): 293–302. doi:10.3354/meps231293
DOI: 10.3354/meps231293

See at: Marine Ecology Progress Series Open Access | Marine Ecology Progress Series Restricted | Marine Ecology Progress Series Restricted | CNR ExploRA Restricted | Marine Ecology Progress Series Restricted | Marine Ecology Progress Series Restricted | Marine Ecology Progress Series Restricted


2002 Journal article Open Access OPEN

Foraging strategies of the black-legged kittiwake Rissa tridactyla at a North Sea colony: evidence for a maximum foraging range
Daunt F., Benvenuti S., Harris M. P., Dall'Antonia L., Elston D. A., Wanless S.
Black-legged kittiwakes Rissa tridactyla on the Isle of May, southeast Scotland, feed predominantly on the lesser sandeel Ammodytes marinus, an abundant, pelagic fish that is currently the subject of the largest fishery in the North Sea. The population of black-legged kittiwakes on the Isle of May is declining, and the fishery has been implicated. In order to assess this concern, there is an urgent need to improve our understanding of the factors that affect black-legged kittiwake foraging behaviour. During 1999, we carried out a detailed study of the foraging strategies of black-legged kittiwakes using purpose-built activity loggers that allowed us to distinguish 4 key behaviours: travelling flight, foraging flight, presence on the sea surface and attendance at the nest. We used the data to model 2 key aspects of time allocation at sea: (1) the relationship between the travelling time and trip duration and (2) the ratio of time spent actively foraging to time of inactivity on the sea surface at the foraging grounds. We found that a broken-stick model with a flat asymptote was the best fit for the relationship between travelling time and trip duration. Using published flight speeds for this species, we calculate that breeding black-legged kittiwakes on the Isle of May had a maximum range of 73 ± 9 km from the colony. We speculate that this upper limit is dictated by the distribution of prey rather than any energetic constraint on flight costs: a large sand bank complex, known to have high concentrations of lesser sandeels, lies entirely within this range. There was no consistent pattern in the ratio of the active to inactive components of the foraging trip, suggesting that this species exhibits highly flexible foraging strategies at sea, probably reflecting the patchy and unpredictable distribution and availability of its prey. Our findings suggest that the birds are feeding on sandeels at the same time and in the same area as the operations of the sandeel fishery.Source: Marine ecology. Progress series (Halstenbek) 245 (2002): 239–247. doi:10.3354/meps245239
DOI: 10.3354/meps245239

See at: Marine Ecology Progress Series Open Access | Marine Ecology Progress Series Restricted | Marine Ecology Progress Series Restricted | CNR ExploRA Restricted | Marine Ecology Progress Series Restricted | Marine Ecology Progress Series Restricted


2002 Journal article Restricted

Nonlinear least Lp-norm filters for nonlinear autoregressive (alfa)-stable processes
Kuruoglu E. E.
The ?-stable distribution family has received great interest recently, due to its ability to successfully model impulsive data. ?-stable distributions have found applications in areas such as radar signal processing, audio restoration, financial time series modeling, and image processing. Various works on linear parametric models with ?-stable innovations have been reported in the literature. However, some recent work has demonstrated that linear models are not in general adequate to capture all characteristics of heavy-tailed data. Moreover, it is known that the optimal minimum dispersion estimator for ?-stable data is not necessarily linear. Therefore, in this paper, we suggest a shift in the interest to nonlinear parametric models for problems involving ?-stable distributions. In particular, we study a simple yet analytic nonlinear random process model namely polynomial autoregressive ?-stable processes. Polynomial autoregression and Volterra filtering have been successful models for some biomedical and seismic signals reflecting their underlying nonlinear generation mechanisms. In this paper, we employ ?-stable processes instead of classical Gaussian distribution as an innovation sequence and arrive at a model capable of describing asymmetric as well as impulsive characteristics. We provide a number of novel adaptive and block type algorithms for the estimation of model parameters of this class of nonlinear processes efficiently. Simulation results on synthetic data demonstrate clearly the superiority of the novel algorithms to classical techniques. The paper concludes with a discussion of the application areas of the techniques developed in the paper, including impulsive noise suppression, nonlinear system identification, target tracking, and nonlinear channel equalization.Source: Digital signal processing (Print) 12 (2002): 119–142. doi:10.1006/dspr.2001.0416
DOI: 10.1006/dspr.2001.0416

See at: Digital Signal Processing Restricted | Digital Signal Processing Restricted | Digital Signal Processing Restricted | Digital Signal Processing Restricted | CNR ExploRA Restricted | Digital Signal Processing Restricted


2002 Journal article Restricted

Porosity detection in composite aeronautical structures
Ciliberto A., Cavaccini G., Salvetti O., Chimenti M., Azzarelli L., Bison P. G., Marinetti S., Freda A., Grinzato E.
The paper is devoted to the identification of porosity anomalous levels on composite structures by thermography. The thermal properties mapping of local diffusivity is used for this purpose. Experimental results obtained in different experimental conditions are reported. These results are compared with findings given by Ultrasounds. In particular, enhancement of the defect identification by means of 2D Wavelet transform is presented.Source: Infrared physics & technology 43 (2002): 139–143. doi:10.1016/S1350-4495(02)00132-9
DOI: 10.1016/s1350-4495(02)00132-9

See at: Infrared Physics & Technology Restricted | Infrared Physics & Technology Restricted | Infrared Physics & Technology Restricted | CNR ExploRA Restricted | Infrared Physics & Technology Restricted | Infrared Physics & Technology Restricted


2002 Journal article Restricted

Sex-specific foraging behaviour in a monomorphic seabird
Lewis S., Benvenuti S., Dall'Antonia L., Griffiths R., Money L., Sherratt T. N., Wanless S., Hamer K. C.
Sexual differences in the foraging behaviour of parents have been observed in a number of sexually size-dimorphic birds, particularly seabirds, and the usual inference has been that these sex-specific differences are mediated primarily by differences in body size. To test this explanation, we compared the foraging behaviour of parents in a monomorphic seabird species, the northern gannet Morus bassanus. Using specifally designed instruments and radio telemetry we found that individuals of both sexes were consistent in the directions and duration of their foraging trips. However, there were significant differences in the foraging behaviour of males and females. Female gannets were not only more selective than males in the areas where they foraged, but they also made longer, deeper dives and spent more time on the sea surface than males. As the sexes are morphologicall y similar in this species, then these differences are unlikely to have been mediated by body size. Our work highlights the need to investigate sexual differences in the foraging behaviour of seabirds and other species more closely, in order to test alternative theories that do not rely on differences in body size.Source: Proceedings of the Royal Society of London. Series B, Biological sciences 269 (2002): 1633–1740.

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2002 Journal article Restricted

Significance of automatically detected word recurrences in dream associations in dreaming
Barcaro U., Calabrese R., Cavallero C., Diciotti R., Navona C.
Verbal data files including dream reports and associations with the report items were subjected to automatic analysis aiming at the recognition of word recurrences. The research was based on the following assumptions: the associations can provide information about the dream sources; the recognition of word recurrences in text files can be a useful tool for the study of dreaming; the identification of links between different dream sources can provide an interesting insight into the phenomenon of dreaming. The principal result obtained was that word recurrences often evidence possible significant links between dream sources. A number of the possible links evidenced by the automatic analysis not only escaped the subject's notice, but might also be unexpected for an analyzer not assisted by a computer.Source: Dreaming (N.Y.N.Y.) 12 (2002): 93–107.

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2002 Journal article Restricted

Time-frequency based detection in impulsive noise environments using alpha-stable noise models
Coates M. J., Kuruoglu E. E.
We develop near-optimal test statistics for the detection of arbitrary non-stationary second-order random signals in impulsive noise, modelled using a bivariate, isotropic ?-stable distribution. The test statistics are derived by approximating the noise model using a mixture of Gaussians, trained using an expectation-maximisation algorithm. We consider the extension to the case when the signal to be detected is subjected to an unknown time-frequency or time-scale shift, and show that approximations to locally optimal test statistics can be implemented using bilinear time-frequency or time-scale representations. We demonstrate that the performance of the locally optimal linear receiver is poor in even mildly impulsive noise; the alternative detection statistics proposed in this paper offer considerably enhanced performance.Source: Signal processing (Print) 82 (2002): 1917–1925. doi:10.1016/S0165-1684(02)00319-5
DOI: 10.1016/s0165-1684(02)00319-5

See at: Signal Processing Restricted | Signal Processing Restricted | Signal Processing Restricted | Signal Processing Restricted | Signal Processing Restricted | CNR ExploRA Restricted | Signal Processing Restricted


2002 Journal article Restricted

A web site for the "Giorgio Ronchi" foundation
Galligani A., Salvetti O.
This paper describes the main aspects of the Web Site designed and realized for the "Giorgio Ronchi" Foundation at the lnstitute of· lnfornation Processing of the Italian National Research Council,, in Pisa. The site is accessible remotely via network, allows connecting on-line the Foundation Library and it offers an actual and efficient instrument for giving worldwide knowledge about the Foundation and its activity.Source: Atti della Fondazione Giorgio Ronchi (1976) LVII (2002): 195–208.

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2002 Journal article Restricted

Come i computer hanno influenzato le discipline umanistiche
Salerno E.
An abstract is not availableSource: Jekyll. comm. 3 (2002).

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2002 Journal article Restricted

A Web-based resource discovery facility for a Geo-Data Server
Galligani A., Salvetti O.
This article deals with the design of a resource discovery system, based on a Web interface, for searching and downloading data stored in a Geo-Data Server. The main features of the Geo-Data Server are the design of a cartographic and image database, following international standards, a relational catalogue, containing meta-information on the archived data, and a high-level interface to access the system. The Geo-Data Server implements a distributed system where data are appropriately organised for remote consultation.Source: Electronic geosciences 7 (2002): 1–10. doi:10.1007/s10069-002-0003-5
DOI: 10.1007/s10069-002-0003-5

See at: Visual Geosciences Restricted | Visual Geosciences Restricted | Visual Geosciences Restricted | Visual Geosciences Restricted | Visual Geosciences Restricted | CNR ExploRA Restricted


2002 Journal article Open Access OPEN

Blind image analysis helps research in cosmology
Salerno E., Bedini L., Kuruoglu E. E., Tonazzini A.
Blind image processing techniques are being studied at IEI-CNR, with the aim of extracting useful information from satellite radiometric maps of the celestial sphere. This activity is undertaken on behalf of the European Space Agency Planck Surveyor Satellite programme.Source: ERCIM news 49 (2002): 44–45.

See at: CNR ExploRA Open Access | www.ercim.eu Open Access


2002 Journal article Unknown

Strumenti musicali e iper-strumenti
Tarabella L., Bertini G.
An abstract is not availableSource: Ricerca & Futuro (Testo stamp.) 25 (2002): 37–38.

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2002 Journal article Restricted

Structural control of a masonry vault
Brocato M., De Domenico A., Zanghi F.
Ancient buildings sometimes need to be supplied with reinforcing structures. Active reinforcements can be the right answer to quite complex, and widely unknown working conditions. Their design requires, in particular, the choice of a control policy and the optimal design of sensors-processors-actuators. The vault of the Maggior Consiglio Hall in the Duke's Palace of Genoa, although presently supported by an auxiliary truss, undergoes relatively large displacements, probably due to temperature variations; the use of stiffer links to reduce these displacements may result into high thermal stresses. This problem is studied here as an example of the design of a control system. A numerical model of the structure is proposed, and a performance function is considered; a feedback loop is designed and the corresponding algorithm is given. The inverse problem of determining the actuating forces following variable external condition to achieve the best performance is solved. Results show the feasibility of the method.Source: Structural and multidisciplinary optimization (Print) 24 (2002): 387–395.

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2002 Journal article Restricted

Neural Method for three-dimensional image matching
Di Bona S., Salvetti O.
This paper presents the "Volume-Matcher 3D" project, an approach for a data-driven comparison and registration of three-dimensional (3D) images. The approach is based on a neural network model derived from self-organizing maps and extended in order to match a full 3D data set of a "source volume" with the 3D data set of a "target volume." The method developed has been tested on real cases of interest in medical imaging. The results have been evaluated on the basis of both an objective mathematical function and visual analysis performed by an expert. The software was implemented on a high performance PC using AVS/Express(TM). © 2002 SPIE and IS&TSource: Journal of electronic imaging (Print) 11 (2002): 497–506. doi:10.1117/1.1501572
DOI: 10.1117/1.1501572

See at: Journal of Electronic Imaging Restricted | Journal of Electronic Imaging Restricted | Journal of Electronic Imaging Restricted | Journal of Electronic Imaging Restricted | Journal of Electronic Imaging Restricted | CNR ExploRA


2002 Journal article Open Access OPEN

Quantitative descriptors of NREM sleep microstructure
Navona C., Barcaro U., Bonanni E., Maestri M., Murri L., Salvetti O.
The aim of the research has been to apply a method based on the automatic computation of five band - related descriptors to the quantitative analysis of the various microstructure phenomena occur- ring during NREM sleep.Source: Journal of sleep research (Print) 11 (2002): 160–160. doi:10.1046/j.1365-2869.11.s1.7.x
DOI: 10.1046/j.1365-2869.11.s1.7.x

See at: Journal of Sleep Research Open Access | Journal of Sleep Research Restricted | Journal of Sleep Research Restricted | Journal of Sleep Research Restricted | Journal of Sleep Research Restricted | CNR ExploRA Restricted