Alberto L. Geraci

Rapid determination of the fatigue curve by the thermographic method

Abstract The available methods for the rapid determination of the fatigue limit (Metall. Ital. 27 (1935) 188; Rev. Metall. XVIII (1951) 11) and for the analysis of the dynamic parameters of crack mechanics (ASTM-STP 519, 246; J. Mater. 5 (1970) 4; J. Appl. Mech. 67 (1945) A159; Exp. Mech. 5 (1965) 193; Fatigue Engng Mater. Struct. 1 (1979) 37; J. Basic Eng. Trans. ASME, Ser. D 85 (1963) 528) require the determination of parameters which are highly specialised (KI, J-integral) and often too closely linked to the micro-mechanics of the material, downgrading the engineering aspects of the problem and its design definition. Following their research into the use of the thermographic method to determine the dynamic properties of materials and components commonly used in the industrial sector (hereafter called the Risitano method [Int. J. Fatigue Mater. Struct. Components 22/1 (1999) 65]), the authors now present a procedure for the definition of the whole fatigue curve.

Water quality mapping of Augusta Bay, Italy from Landsat-TM data

Abstract Landsat Thematic Mapper (TM) digital data were used to map the distributions and concentrations of selected water quality indicators in and around Augusta Bay, Sicily. The general approach involved near-simultaneous aquisition of TM data and water quality samples from 42 sites, laboratory analysis of samples, extraction of sample site digital numbers from the TM data, development and validation of regression models based on sample data, application of models to the entire study area, and generation of colour-coded output maps. Results were good for modelling temperature, turbidity, Secchi disk depth and chlorophyll-a, and indicate that remotely-sensed data may be applicable to monitoring water quality in this geographic area.

A regional assessment of land-use/land-cover types in Sicily with TM data†

Digital analysis of Landsat-5 Thematic Mapper (TM) data was evaluated as a mechanism for mapping the distribution of nine land-use/land-cover types found within five regional provinces of Sicily. Digital data from TM wavebands 1, 4, 5 and 7, along with corresponding ground truth data for 280 training sites, were used to characterize the spectral response of the land-use/land-cover categories under study. Training data were then input to supervised and unsupervised classification algorithms to map the distribution of the nine categories within eight Landsat-5 TM quarter-scenes needed for complete coverage of the study area

Determination of the fatigue limit of an austempered ductile iron using thermal infrared imagry

Previous work by the authors showed that the endurance limit of specimens, or mechanical components, can be predicted using thermal infrared imagery. The new technique enables the determination of the fatigue strength limit in a comparatively short period of time (few thousands cycles), and using very few specimens (theoretically only 1). The present work applies this technique to rotating-bending test specimens of austempered ductile iron, an alloy whose fatigue limit is, due to the high scatter dispersion of the data points and the long testing period required, generally difficult to determine by the traditional technique. This material exhibited higher fatigue strength than the familiar nodular cast iron. This was confirmed by the results derived from the traditional Wohler test and the new technique, and supported by the data gathered from literature.

The choice of thermal analysis to evaluate the monoaxial fatigue strength on materials and mechanical components

A historical review was carried out, in order to point out the phases leading to investigate the fatigue resistance of materials and mechanical components, using quick and direct methodologies. Starting from researches performed in the early 1980s, the progresses in the research conducted by the Catania group and other investigators, significantly contributing to the increasing interest in the thermographic analysis of the fatigue phenomenon and, more specifically, to the experimental evaluation of the energy release under fatigue loading, were described.

DISPERSANT APPLICATION BY HYDROFOIL: HIGH SPEED CONTROL AND CLEANUP OF LARGE OIL SPILLS

ABSTRACT Experiments undertaken in different parts of the world have shown so far that cleanup at a speed greater than 10 knots is unadvisable due to the bow wave breaking up the oil film on the water. The purpose of this paper is to demonstrate that a high-speed craft such as a hydrofoil, when flying foilborne, solves this problem.

The use of aircraft and satellite remote sensing during the oil spill in the Gulf of Genoa, Italy

During the recent oil spill in the Gulf of Genoa, the Italian Coast Guard (Capitanerie di Porto) carried out remote sensing missions over the Tyrrhenian Sea, using its Piaggio P.166–DL3 aircraft, configured for marine ecological surveillance. The purpose of the missions was to control the oil spill from the ship, its spreading into the sea, the evolution of the phenomenon caused by the accident, as well as its influence on the coastal zone. The Aircraft Remote Sensing System, integrated in the Italian Coast Guard aircraft, included Aerial Camera System (ACS), Bispectral Scanner System (BSS), Multispectral Scanner System (MSS), FLIR (Forward Looking Infrared) System. The most significant data, acquired during the missions, were processed with computer‐aided techniques, using systems for image digital analysis. The interpretation, process, and analysis made it possible to obtain color‐coded imagery, showing oil pollution, distinguishing 2 types of it as a function of the intensity level, calculating their e...

Use of neural networks on parallel architecture for the classification of plane figures

The use of neural networks for recognizing and measuring objects is proposed. A review of the state-of-the-art of neural network systems and communicating sequential process formalizing was made, in order to select network type and topology. After a standard image acquisition step, the developed system prototype was implemented on parallel architecture, based on Transputer network following the same distribution of the nodes, that constitute the activation functions typical of all types of neural network. The realization of the prototype was carried out in C++ language,l for its portability to different platforms. Then, the developed algorithm was optimized by the translation into the original OCCAM language. The study constitutes the first effort of a research activity, intending to link recognition and measuring of objects to vectorial imagery, using different image acquisition systems (including those working in the infrared band) and the developed system prototype, with software dedicated to industrial drawing applications.

Study of deformations in objects under stress using digital image analysis

Deformations of a plate under different loading conditions were determined using remote sensing techniques. Imagery of the plate under investigation, acquired with a TV-camera based system, was analyzed, in order to measure electronically the average radiance over the plate through the digital numbers in each pixel. Moving from the knowledge of the radiant energy, it was possible to determine deformations, directly related to radiance, analyzing pixel-by- pixel image variations. Radiometric and geometrical considerations allowed determining deflections of the plate, after introducing a correction factor, to consider the response of the acquisition system. They were found in good accordance with those resulting from the use of traditional methods, and proved the working of the proposed technique.

The Remote Sensing Approach. A Modern Technique To Control Sea Pollution.

In the following pages, some of the most significant activities, developed at the Remote Sensing Group of the University of Catania in Italy over a near 20-year period in the field of remote sensing related applications for environmental control, are reported briefly. The remote sensing approach is proposed as a new modern technique, to control sea pollution, and more in general the marine environment, having proved its effectiveness as a means to integrate, and in a number of applications, to substitute conventional investigation techniques.