Search results for "damage [radiation]"
showing 10 items of 101 documents
Digital signal processing for rail monitoring by means of ultrasonic guided waves
2007
Recent train accidents have reaffirmed the need for developing rail defect detection systems that are more effective than those used today. One of the recent developments in rail inspection is the use of ultrasonic guided waves (UGWs) and non-contact probing techniques to target transverse-type defects. Besides the obvious advantages of non-contact probing, that include robustness and a potential for large inspection speed, such a system can theoretically detect transverse defects under horizontal shelling or head checks. This paper demonstrates the effectiveness of digital signal processing to enhance the damage detection sensitivity of the non-contact system. The method proposed here comb…
An integrated structural health monitoring system based on electromechanical impedance and guided ultrasonic waves
2015
We propose a structural health monitoring (SHM) paradigm based on the simultaneous use of ultrasounds and electromechanical impedance (EMI) to monitor waveguides. Methods based on the propagation of guided ultrasonic waves (GUWs) are increasingly used in all those SHM applications that benefit from built-in transduction, moderately large inspection ranges, and high sensitivity to small flaws. Meantime, impedance-based SHM promises to adequately assess locally the structural integrity of simple waveguides and complex structures such as bolted connections. As both methods utilize piezoelectric transducers bonded or embedded to the structure of interest, this paper describes a unified SHM para…
Experimental Investigation for Degradation Analysis of an RC Italian Viaduct and Retrofitting Design
2020
AbstractThe degradation state of RC bridge structures is one of the most important and difficult aspects to be interpreted. For these structures, structural analysis using FEM requires a reliable d...
Low stiffness variation in structural systems: identification and localization
2008
When a very low damage occurs, the undamaged structural response totally overlaps the damaged one either in time domain or in frequency domain; on the other hand, by considering some characteristics of the analytical signal, such as the phase, it has been possible to develop a damage identification procedure that allows the identification and localization of damage even if the structure experiences multiple damages at the same time. This procedure is also robust with respect to the presence of measuring noise. In order to assess the validity of the proposed damage identification procedure, numerical applications on single degree of freedom and 2 DOF and 4 DOF are presented using data record…
Improved Planning In-Service Inspections of Fatigued Aircraft Structures Under Parametric Uncertainty of Underlying Lifetime Models
2014
Certain fatigued structures must be inspected in order to detect fatigue damages that would otherwise not be apparent. A technique for obtaining optimal inspection strategies is proposed for situations where it is difficult to quantify the costs associated with inspections and undetected failure. For fatigued structures for which fatigue damages are only detected at the time of inspection, it is important to be able to determine the optimal times of inspection. Fewer inspections will lead to lower fatigue reliability of the structure upon demand, and frequent inspection will lead to higher cost. When there is a fatigue reliability requirement, the problem is usually to develop an inspection…
Numerical modelling of low velocity multi-impact test on different stacking sequences
2019
The use of composite materials in the industrial field has been growing significantly for many years. This increase is explained by the fact that the industry, especially aeronautics which was pioneering in this field, is interested in the lightening of structures in order to be able to take up the new environmental challenges. Whether in the aeronautical field or in the land transport sector, structural elements may undergo multi-impactsor impact. Even at low velocitypose a threat to the integrity of the material and the structure itself. The objective of this work is to propose a numerical model to determine the damage within a composite structure subjected to low energy multi-impact. The…
Il danno alla persona
2022
Il saggio analizza il decisivo contributo di Renato Scognamiglio all'evoluzione del danno alla persona nell'ordinamento giuridico italiano. Dopo aver ripercorso gli studi dedicati da Scognamiglio al tema, il saggio verifica l'impatto di tali studi sulla della riflessione scientifica sul danno non patrimoniale e sugli orientamenti della giurisprudenza. L'autore propone una razionalizzazione e l'integrazione delle conclusioni oggi prevalenti al fine di ridurre, per quanto possibile, le oscillazioni interpretative e l'incertezza applicativa. The essay analyzes the decisive contribution of Renato Scognamiglio to the evolution of damage to the person in the Italian legal system. After having ret…
Progressive paraparesis in a 66-year-old man - a case study
2023
The paper presents a case of progressive paraparesis in a 66-year-old man with no history of tick bite, who was finally diagnosed with neuroborreliosis on the basis of the performed tests. Proper diagnosis and introduction of causal treatment resulted in rapid improvement of the patient’s condition.
Intra- and extra-cellular DNA damage by harmine and 9-methyl-harmine
2014
It is known that b-carbolines are able to produce photosensitized damage in cell-free DNA, but there is little information on their effects on cellular DNA. Therefore, we have analyzed the DNA damage produced by harmine and 9-methyl-harmine under UVA irradiation in V79 cells, together with the associated generation of micronuclei and photocytotoxicity. The results indicate that the most frequent photoproducts generated in the cellular DNA are modified purines such as 8-oxo-7,8-dihydroguanine. Only relatively few single-strand breaks were observed. CPDs were absent, although they were generated in cell-free DNA irradiated under the same conditions. The overall extent of DNA damage in the cel…
A modified Ant Colony damage identification algorithm for not well spaced frequency systems
2012
Damage identification is of primary concern in many fields of civil engineering. Usually the damage is detected from the variation of structural response induced. When the damage level is very low, incipient damage, this variation is hardly seen. In the present work is studied the case of not well spaced frequency systems. Identification problem is formulated as a minimum problem of a functional expressed in term of damage parameters. The minimum problem is solved by heuristic algorithm, ACORL.