1,720,993 research outputs found
Between scientific rigor and perceptive component. Representing the landscape of the “royal salt works” of Cagliari in the 19th century (Sardinia, Italy)
Full text linkThe case study is part of a research that analyzes the potentiality of historical maps as a tool to support the knowledge and protection of the landscape. The main interest of this article is to highlight data qualities and communicative capacities of 19th century cartography of Sardinia also in relation to the current state of the art. The drawing of landscape and territory at this time shows an interesting ability to combine scientific rigor and perceptive component that will have its maximum expression in 1845 with the work of the general Alberto Ferrero Della Marmora.
Starting from a critical analysis of the archive documents, the methodology adopted in this case study needs the drawing/design of a geo-referenced
database aimed at a comparison between historical maps and the series of aerial surveys made available by Cartography Service of the
Sardinia Region. The subject of this analysis are some interesting drawings that describe the system of “Royal salt works” of Cagliari designed by Piedmontese government in the first half of the nineteenth century, surveyed and represented by military officers.
The territorial data recorded in the examined maps shows an interesting compatibility with the most recent acquisitions and allows a diachronic
analysis of the transformations. To this end – putting together the high precision of current survey and representation methods with information
and immediacy of historical cartographic production - the drawings are analyzed, elaborated and “communicated” through graphics models able
to express by signs the complexity of a stratified landscape
Fatigue and damage analysis on aeronautical CFRP elements under tension and bending loads: Two cases of study
No full textThe present work is focused on experimental monitoring procedures to investigate stresses and damage settlement during fatigue tests of CFRP elements under bending and tensile loads. Continuous damage accumulation, coupled with mechanical properties degradation are monitored with ultrasonic inspection and with thermographic full field analysis, during long lasting HC fatigue loads. Effects of localized bending loads and artificial composite wrinkle presence within a notch are source of delamination initiation, investigated two different types of specimens under fatigue. Combined monitoring approaches, based on thermo-elastic and dissipative phenomena, together with ultrasonic through thickness properties variations are claimed to offer precise damage state and localization during tests, subsequently aided by FEM damage model analysis in case of static failure zone identification, to be compared with experimental data; in addition, experimental DIC computation of deformation on specimen critical zones is performed in order to check failure and delamination initiation spot. The thermal parameters and experimental compliance correlation seem to indicate a similar signal variation during damage progress, verified also by contemporaneous ultrasonic inspections of some specimens in the failure zones of CFRP elements
Comparative Analysis of Thermal Processing Approaches for a CFRP Element Aided by UT Control
No full textThe present work resumes thermal data processing with most common algorithms in literature and introduces in addition a different data processing strategy, proposed to improve subsurface defect detection on industrial composites. These materials are successfully controlled with infrared Non-Destructive Investigations, since defects are easily detected by temperature response under thermal pulses with reliable results. To reduce application limits for non-destructive inspections, the proposed research shows possibility to combine pulsed thermographic technique with accurate image-processing methods implemented in Matlab environment for a reliable and rapid characterization of subsurface and internal damage. Thermal processing methods are evaluated for the proposed case of study, as the well-established DAC, PCT, TSR procedures. In addition, the authors proposed a better defect characterization that is achieved with refined data processing and accurate experimental procedures, providing detailed contrast maps where defects are easily distinguished. This improved algorithm automates the defect mapping and enhances the accuracy of defects inspection, optimized to identify defect boundaries according to spatial variations in neighboring of each calculation point of the whole thermal frame. Thermal data are evaluated with standard methods and the local boundary method is for carbon-fiber composite specimens with artificial defects, evaluating processed images obtained by different methods employing the Tanimoto criterion. Proposed thermal computation method is found suitable for automatic mapping of defect distribution and optimized for simultaneous defect boundaries’ detection in terms of Tanimoto criterion, in the inspected structure. In addition, ultrasonic controls are carried out for detection comparison between different control procedures
Application of Pulsed Thermography and Post-processing Techniques for CFRP Industrial Components
No full textSeveral studies demonstrate the effectiveness of pulsed thermography for detection and visualization of sub-superficial flaws in composites. Continuous improvement of thermal data manipulation makes active thermography an attractive and powerful inspection method for industrial process control and maintenance aims. Therefore, temperature image-processing is the major ongoing challenge in the thermographic research field. However, the particular interest for thermographic inspections is to be more addressed to its simple and relatively fast industrial application; an appropriate image processing tool should be implemented and verified on industrial components, containing manufacturing and in-service defects. In the proposed research, well-established and previously proposed methods were analysed and compared for different defect typology inside three CFRP components. The main goal is not solely focused on establishing the suitable data processing approach, providing detection limits of processed data in terms of damage type, size and distribution. The aim of proposed work is to present detailed examples of thermal imaging methods applied on similar critical defects, evaluating different results among methods in terms of defects mapping capabilities and Tanimoto evaluation criterion, coupled also with the signal-to-noise ratio as assessment of defect detectability
Graphical analysis of historical maps. Traces of industrial archeology in the south-eastern sector of the city of Cagliari. (Sardinia, Italy)
Full text linkThe contribution proposed is a part of a research aimed at the definition of methodologies for the analysis and representation of the landscape of Sardinia, with particular reference to one of its most important and characteristic versions: the landscape of the wetlands. The history of the city of Cagliari is strongly linked to the sea and the lagoons, elements that constituted the authentic "settlement principle" where the lagoons, in particular, were sources of decisive resources as well as for fishing, for the landing (especially the western ponds) and salt extraction (mainly from the Molentargius pond). The case study consists in a part of the regional natural park “Molentargius-Saline”, a system of considerable environmental and landscape value that hosts examples of industrial archeology. Through a multi-scale approach that links traditional and IT tools it is possible to define some representative graphic models of the studied landscape in order to plan its protection and enhancement. The comparison between historical maps and aerial images here presented is the first step of a path of knowledge that explore, analyze and want to highlight the most important transformation occurred in this area since the nineteenth century and a partial preservation of the its historical cultural landscape
Rilievo e rappresentazione di una piazzaforte. Le mura di Cagliari nel Settecento.
No full textStarting from the sixteenth century, the strategic position of the stronghold of Cagliari within the Mediterranean has required a constant strengthening of its defenses. The insertion of "modern" forms have changed the medieval design of the city for almost three centuries. The solutions adopted can be studied with the support of a series of maps which document with great precision the modifications of the bastioned fronts of the Marina district (Lapola) and of the Castello district in the period between the 16th and 19th centuries. Among these maps, the eighteenth-century plan called “Pianta della città di Cagliari e dei suoi borghi”, elaborated by Piedmontese engineers, is the first to describe the capital of Sardinia with a great detail and precision allowing an in-depth study of the design and consistency of the ancient city walls and the preservation of the memory of an excellent example of military architecture
Verso un protocollo d’indagine pluridisciplinare: la cortina di Santa Chiara a Cagliari
No full textIl contributo mostra l’impostazione di una ricerca pluridisciplinare che analizza un settore della città storica, interessato a partire dal Cinquecento da importanti modificazioni di assetto urbano.
L’impiego di metodologie di diagnostica non distruttiva affianca e supporta la ricerca storica ed il rilevamento delle architetture presenti nell’area, con l’obiettivo di fornire un quadro completo delle dinamiche costruttive che hanno interessato un particolare segmento di tale area, compreso tra il bastione di Santa Croce e la torre dell’Elefant
La piazzaforte di Alghero (Sardegna) nella seconda metà del Cinquecento. Analisi grafica dei progetti e nuovi dati archeologici
No full textA Brief Review and Advances of Thermographic Image - Processing Methods for IRT Inspection: a Case of Study on GFRP Plate
No full textThe present work introduces a different data processing strategy, proposed in order to improve sub-surface defect detection on industrial composites; in addition, a resume of thermal data processing with most common algorithms in literature is presented and applied with new data. A deep comparison between the common absolute contrast, DAC, PCT, TSR and derivative methods and a new proposed contrast mapping procedure is implemented. Thermographic inspection was done in reflection mode on a Glass Fiber Reinforced Plastic plate, with flat bottom hole defects. Thermal data computation method is found to be critical for simultaneous defect detection and automatic mapping, optimized to identify defect boundaries at specific depth, with help of accurate image processing, implemented in a Matlab GUI for a reliable and rapid characterization of internal damage. The new processing approach, the Local Boundary Contrast method, elaborates different contrast maps and facilitates recognition of damage extension. Tanimoto criterion and the signal-to-noise ratio method were applied as a criterion to assess defect detectability of various processing methods
Stress/strain state for critical components of a jet engine aeronautical compressor
No full textIn order to prevent in-flight fatigue failure, a numerical analysis of in service-operative cases is an useful approach for preliminary evaluation of most stressed and critical zones in components of aeronautical engine. The zero-stage compressor rotor disk and blades represent one of the most critical part of aircraft turbojet. This paper presents a verification FEM analysis of this component. An accurate 3D scanning was performed to reconstruct both blade and disk real geometry and the detailed point cloud was obtained and opportunely elaborated by using specific software to generate CAD sections and volumes given in input to finite element analysis. The stress field due to different operating conditions is studied for a suitable evaluation of the most stressed and critical areas where a failure may occur, particularly near the rotor connection under contact conditions. FEM and flight data analysis are finally used for a subsequent fatigue life verification, based on classical Palmgren Miner’ rule. The suggested procedure for verification of engine aeronautical component is here optimized for maintenance program improvements
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