Search results for "Hierarchical"
showing 10 items of 260 documents
Forest in Sicily
2017
The Sicilian forestal landscape is part of an agro-forestal environment where wood stations, often spatially organized on grazing, alternate to scrublands and cultivated areas. In Roman times, the island’s forest surface amounted to about one million hectares, but the deforestation practices carried out to give room to agriculture, along the centuries, reduced this surface to about a third. Forests are still well preserved on mountains and above all on the Sicani, Madonie, and Nebrodi ranges and on Mt. Etna. On the remaining territory, the forest landscape is quite irregular and characterized by small stations within agricultural and grazing territories. On the basis of the last Regional Fo…
Geostatistical techniques for runoff mapping: an application to Sicily, Italy
2011
The availability of reliable and long time series of runoff data is fundamental for most of the hydrological analyses and for the assessment and the management of water resources even in condition of global climatic change. However, hydrologic data sets are often characterized by a short duration and also suffer from missing data values, mainly due to malfunctioning of gauging stations for a specific period. In order to overcome this problem and obtain long and continuous runoff time series, different models and methods have been previously developed and proposed. While some models, used to extent the streamflow record, are conceptual, empirical, regressive models based on the rainfall inpu…
Pictorial information retrieval with uncertain knowledge
1990
In the paper an integrated pictorial database is described. The design of the data management requires many efforts to preserve consistency and integrity. The retrieval operations are designed to support a uniform view of heterogeneous information including uncertain ones; in this last case, non-standard techniques have to be developed. Applications to astronomical images and an outline of the implementation status are given.
Dissimilarity Measures for the Identification of Earthquake Focal Mechanisms
2013
This work presents a study about dissimilarity measures for seismic signals, and their relation to clustering in the particular problem of the identification of earthquake focal mechanisms, i.e. the physical phenomena which have generated an earthquake. Starting from the assumption that waveform similarity implies similarity in the focal parameters, important details about them can be determined by studying waveforms related to the wave field produced by earthquakes and recorded by a seismic network. Focal mechanisms identification is currently investigated by clustering of seismic events, using mainly cross-correlation dissimilarity in conjunction with hierarchical clustering algorithm. By…
A fast BEM for the analysis of plates with bonded piezoelectric patches
2010
In this paper a fast boundary element method for the elastodynamic analysis of 3D structures with bonded piezoelectric patches is presented. The elastodynamic analysis is performed in the Laplace domain and the time history of the relevant quantities is obtained by inverse Laplace transform. The bonded patches are modelled using a semi-analytical state-space variational approach. The computational features of the technique, in terms of required storage memory and solution time, are improved by a fast solver based on the use of hierarchical matrices. The presented numerical results show the potential of the technique in the study of structural health monitoring (SHM) systems.
Structured methodology for selection of maintenance key performance indicators: Application to an oil refinery plant
2017
The novel contribution of the work is the proposal of a structured multi-step methodology that may support the Decision Maker (DM) in the measurement of maintenance performance by means of Maintenance Key Performance Indicators (MKPIs). To this aim, a multi-level hierarchical framework able to synthesize the most meaningful aspects affecting the maintenance results is designed. Then, MKPIs are selected from the literature, assigned to the hierarchical framework and ranked by an Analytic Hierarchy Process-based approach with incomplete comparison matrices. A mathematical model is finally formulated to select the optimal set of MKPIs. The methodology is implemented in an oil refinery plant an…
Analisi di sicurezza nella procedura di protonterapia oculare applicata presso i Laboratori del Sud dell’INFN di Catania
2017
A partire dal 2002, l’Azienda Ospedaliera Universitaria “Policlinico Vittorio Emanuele” di Catania ha effettuato il trattamento di circa 350 pazienti affetti da neoplasie oculari mediante fasci di protoni prodotti con il ciclotrone disponibile presso i Laboratori nazionali del Sud (LNS). Tale impianto viene utilizzato per attività di ricerca nell’ambito della fisica sperimentale, per cui è stato necessario modificare le caratteristiche del fascio, rendendolo idoneo alle applicazioni cliniche. Il lavoro di ricerca ha riguardato lo svolgimento della analisi del rischio volto ad individuare possibili fallimenti nelle procedure adottate per il trattamento del paziente sottoposto a cicli di prot…
Automatic classification of acoustically detected krill aggregations: A case study from Southern Ocean
2022
Acoustic surveys represent the standard methodology to assess the spatial distribution and abundance of pelagic organisms characterized by aggregative behaviour. The species identification of acoustically observed aggregations is usually performed by taking into account the biological sampling and according to expert-based knowledge. The precision of survey estimates, such as total abundance and spatial distribution, strongly depends on the efficiency of acoustic and biological sampling as well as on the species identification. In this context, the automatic identification of specific groups based on energetic and morphological features could improve the species identification process, allo…
Is There Anything New to Say About SIFT Matching?
2020
SIFT is a classical hand-crafted, histogram-based descriptor that has deeply influenced research on image matching for more than a decade. In this paper, a critical review of the aspects that affect SIFT matching performance is carried out, and novel descriptor design strategies are introduced and individually evaluated. These encompass quantization, binarization and hierarchical cascade filtering as means to reduce data storage and increase matching efficiency, with no significant loss of accuracy. An original contextual matching strategy based on a symmetrical variant of the usual nearest-neighbor ratio is discussed as well, that can increase the discriminative power of any descriptor. Th…
The place of livestock in human-nonhuman relationship among the Wayuu
2020
In the ethnology of indigenous LSA, the Wayuu case has always been considered a peculiar one. Among the main features which make difficult to insert it in the comparative debate on indigenous models of sociality and cosmology in this area, one can mention: pristine introduction of cattle raising; maintenance of political semi-autonomy till very recent times; development, already in the colonial period, of forms of social hierarchy based on ownership of livestock and other material goods; articulation of these forms with a system of matrilineal descent groups; interplay among the inclusive character of the descendants of mixed unions and the shifting of the traits selected for marking ethnic…