1,721,038 research outputs found
Detection of damage in beams subjected to diffused cracking
No full textThis paper addresses the problem of identifying structural damage affecting one zone of a beam using measured frequencies. The beam model has a zone in which the stiffness is lower than the undamaged value. Damage is defined by three parameters: position, extension and degree, which need to be identified in the inverse problem. The solution of the direct problem is first obtained and the peculiarities of damage detection are examined. Two different procedures for damage identification are proposed, which use frequency measurements and take advantage of the peculiarities of the problem: the first procedure is based on the characteristic equation error and the second on the comparison between analytical and experimental frequency values. The identifiability and ill-conditioning properties are discussed by referring to cases with pseudo-experimental data. (C) 2000 Academic Press
Detection of localised damage in plane circular arches by frequency data
No full textThe possibility to detect the structural damage affecting a narrow zone of a doubly hinged plane circular arch by means of a few measured natural frequencies is considered. Such localised damage induces a discontinuity in the bending stiffness of the arch, modelled as a torsion spring joining two adjacent sections and characterised by the location and the stiffness of the spring. The direct problem in the damaged and undamaged case is examined; the inverse problem is then considered. Two different procedures to identify the damage parameters are introduced: the ?rst is based on the search of an intersection point of curves obtained by the modal equation; the second is based on the comparison between the analytical and experimental values of the variation of frequencies passing from the undamaged to the damaged state. In conclusion, the possibility of identifying the damage parameters by means of pseudo-experimental data is examined
Case report of a homicide resolved 15 years later: The robustness of Chelex extraction
No full textDNA typing techniques is one of the most advanced tools for human identification. During the last 10 years, a great number of methods for DNA
extraction and analysis have been introduced to forensic genetic, with considerable success but also with considerable controversy. The success and
validation of a criminal investigation are very closely related to the process used for obtaining and preserving biological evidence.
We report the strategy that we employed to analyze evidences belonging to a homicide happened in Brescia (Italy) in 1992, not resolved at that
time, with the forensic genetic analysis. After 16 years the analysis were conducted on DNA samples extracted with Chelex maintained at 80 8C,
bloodstain, and biological specimens of perpetrators. Standard autosomal and Y-chromosome STR analysis identified the persons involved and
victim’s profiles. This case is of interest as a demonstration of a more successful application of DNA typing in well conserved DNA samples than in
bloodstains kept in the Court Office
Archi circolari piani integri e danneggiati: rilevazioni sperimentali e modelli analitici
No full textQuesto lavoro si propone di: a) illustrare i parametri modali rilevati sperimentalmente in un arco circolare, sia integro che danneggiato da un intaglio; b) confrontare questi con i valori ottenuti da modelli analitici. Il danno è stato modellato per mezzo di una molla rotazionale di opportuna rigidezza localizzata nella sezione corrispondente all’intaglio. Si è osservata una buona corrispondenza tra le evidenze sperimentali ed i risultati analitici
Vibration and damage detection in undamaged and cracked circular arches: Experimental and analytical results
No full textThis paper presents the experimental results of the dynamic behaviour of a circular arch in undamaged and several damaged configurations, and compares them with those obtained by means of analytical methods. The damage is introduced in the undamaged arch by operating a notch and is then modelled as a torsion spring of suitable stiffness localised in the damaged cross-section. Good agreement between analytical and experimental results is observed. An identification procedure based on frequency measurements is proposed and validated. (C) 2008 Elsevier Ltd. All rights reserved
MtDNA: a successful identification case in burned remains
No full textSome human carbonized remains were found in a wood near a lake. Investigations and a macroscopic analysis of the remains led suspicions to a killed and burned 20-year-old man. To identify with certitude the remains, nuclear DNA from the remains and from the alleged mother were analysed. Only at vWA locus an exclusion was found. Because of the delicacy of the case (a murder) and since only the alleged mother’s DNA was available, a mt-DNA analysis was performed. It was
found a good correlation in both HV1 and HV2 regions between the DNA from the remains and the mother’s
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