studio metodologico e rilievi per la costruzione del modello 3D di un sito di cava

Le aree di cava si presentano come oggetti molto complessi per la realizzazione di un rilievo topografico con le metodologie “classiche” in quanto, vista l’estensione e la particolarità dell’andamento delle superfici con piani variamente inclinati sui terrazzamenti e superfici concave o convesse nelle scarpate, si andrebbe incontro all’inevitabile perdita di dettagli del dato ed a una notevole durata dei tempi di rilievo. Lo scopo della presente tesi è quello di definire una metodologia che sia di facile riproducibilità ed applicazione a tutti quei siti di rilievo, anche di diversa natura, che presentino problematiche simili o ad esso riconducibili. La cava oggetto di studio, situata in località “Poggio alla Penna” presso l’abitato di Pomaia, si presenta come valido sito per testare l’integrazione di alcune delle più moderne tecnologie in campo topografico, come il laser scanner a tempo di volo ed il GPS con sistema RTK, evidenziandone i pregi e la sua sfera di applicazione. La metodologia del laser scanner terrestre (TLS) consente di rilevare in tempi notevolmente contenuti la geometria dell’intera area, associando peraltro all’informazione metrica anche l’immagine fotografica reale. La metodologia GPS consente una georeferenziazione dei punti rilevati con il laser ed un controllo sulla precisione finale degli elaborati. Con la fusione di queste due tecnologie è stato possibile ricavare i seguenti prodotti: 1) un modello tridimensionale a mesh triangolari, colorato con colori reali grazie alla fotocamera integrata al laser; 2) della cartografia georiferita a grande scala (1:1000), sia in formato 2D che in 3D e con la possibilità di inserire come sottofondo una fedele immagine dell’oggetto ottenuta attraverso l’elaborazione dei dati laser scanner; 3) il DTM (modello digitale del terreno) dell’area di rilievo, cioè una nuvola di punti 3D georiferiti che rappresentano con opportuno grado di dettaglio, scelto dall’operatore, l’andamento del terreno; Seguendo le metodologie sviluppate nella presente tesi è possibile analizzare tutti gli aspetti più significativi dell’oggetto da rilevare e fornire alla committenza un rilievo completo in ogni aspetto

Structural damage assessment through parametric and nonparametric models

The main purpose of Structural Health Monitoring (SHM) is the assessment of structural conditions in aerospace, mechanical and civil systems. In structural engineering, damage is defined as any permanent change in the structural and geometric properties of a system caused by an external action. Vibration-based damage assessment methods rely on the use of sensors that record the structural dynamic response of a system that is determined by its structural and geometric properties. External disturbances and environmental conditions in which the system operates cause fluctuations of these properties and might hide the change in signature induced by damage. To handle the uncertainties in the determination of the structure’s characteristics, a statistical pattern recognition approach is presented in this thesis. Any statistical approach relies on the statistics of some features that provide a compact representation of the structural properties and that are sensitive to damage. Such features are called damage sensitive features and are extracted from the dynamic response of the structure: their statistical distribution is then analyzed to assess the occurrence of damage. This dissertation focuses on the analysis of the statistical distribution of damage sensitive features which are extracted through parametric and nonparametric algorithms. Cepstral coefficients are features defined in the field of acoustics and, in this thesis, they have been adapted to SHM analyses in order to develop compact damage sensitive features whose extraction requires a low computational effort. In this thesis, cepstral coefficients have been mathematically transformed through a Principal Component Analysis in order to generate damage sensitive features that are barely sensitive to measurement noise, environmental conditions and different excitation sources. In an attempt to develop an automated strategy for structural damage assessment, the search for damage sensitive features has been extended to the estimation of structural mode characteristics obtained through an output-only version of the Inner Product Vector methodology, e.g. considering only the structural response time histories. This new damage assessment procedure requires low computational effort and is capable to identify both the presence of damage and its location. However, one of the critical points of the proposed procedure consists in the manual evaluation of the spectral content of the dynamic responses that requires the user’s intervention. To automatize this procedure, a Bayesian clustering algorithm and a classifier have been successfully implemented and tested. Finally, the robustness of Bayesian regression algorithms to overfitting led us to consider their applicability to the field of system identification in order to provide a reliable estimate of the structural modal parameters that can be used as damage sensitive fea- tures. In fact, one of the main problems of system identification algorithms is that they rely on a regression algorithm that tends to overfit data producing unreliable results. Results provided by the Bayesian regression based system identification algorithm are obtained and compared with the ones coming from standard system identification algorithms

Anti-inflammatory and antioxidant properties of HDLs are impaired in type 2 diabetes.

ObjectiveIn mice, 4F, an apolipoprotein A-I mimetic peptide that restores HDL function, prevents diabetes-induced atherosclerosis. We sought to determine whether HDL function is impaired in type 2 diabetic (T2D) patients and whether 4F treatment improves HDL function in T2D patient plasma in vitro.Research design and methodsHDL anti-inflammatory function was determined in 93 T2D patients and 31 control subjects as the ability of test HDLs to inhibit LDL-induced monocyte chemotactic activity in human aortic endothelial cell monolayers. The HDL antioxidant properties were measured using a cell-free assay that uses dichlorofluorescein diacetate. Oxidized fatty acids in HDLs were measured by liquid chromatography-tandem mass spectrometry. In subgroups of patients and control subjects, the HDL inflammatory index was repeated after incubation with L-4F.ResultsThe HDL inflammatory index was 1.42 ± 0.29 in T2D patients and 0.70 ± 0.19 in control subjects (P < 0.001). The cell-free assay was impaired in T2D patients compared with control subjects (2.03 ± 1.35 vs. 1.60 ± 0.80, P < 0.05), and also HDL intrinsic oxidation (cell-free assay without LDL) was higher in T2D patients (1,708 ± 739 vs. 1,233 ± 601 relative fluorescence units, P < 0.001). All measured oxidized fatty acids were significantly higher in the HDLs of T2D patients. There was a significant correlation between the cell-free assay values and the content of oxidized fatty acids in HDL fractions. L-4F treatment restored the HDL inflammatory index in diabetic plasma samples (from 1.26 ± 0.17 to 0.71 ± 0.11, P < 0.001) and marginally affected it in healthy subjects (from 0.81 ± 0.16 to 0.66 ± 0.10, P < 0.05).ConclusionsIn patients with T2D, the content of oxidized fatty acids is increased and the anti-inflammatory and antioxidant activities of HDLs are impaired

The effect of mean stress on corrosion fatigue life

An experimental investigation of the effect of mean stress on the fatigue life and corrosion fatigue life of cylindrical specimens is presented. Force controlled constant amplitude axial fatigue tests in the regime of 105 to 107 cycles were conducted for two different environments: in air (without corrosion) and in-situ in a corrosive environment, 0.824% NaCl aqueous solution flow. The test results are assessed with respect to various standard models of mean stress influence on fatigue. The reduction in material fatigue strength due to the corrosion environment is evaluated and the results obtained show that in a low salinity aqueous corrosive solution, the fatigue strength at 4x106 is reduced of a factor of 2 compared to no corrosion tests

Apolipoprotein A-I Mimetic Peptides Prevent Atherosclerosis Development and Reduce Plaque Inflammation in a Murine Model of Diabetes

ObjectiveTo determine the effect of the apolipoprotein A-I (ApoA-I) mimetic peptide, D-4F, on atherosclerosis development in a pre-existing diabetic condition.Research design and methodsWe induced hyperglycemia in 6-week-old apoE(-/-) female mice using streptozotocin. Half of the diabetic apoE(-/-) mice received D-4F in drinking water. Ten weeks later, plasma lipids, glucose, insulin levels, atherosclerotic lesions, and lesion macrophage content were measured.ResultsDiabetic apoE(-/-) mice developed ∼300% more lesion area, marked dyslipidemia, increased glucose levels, and reduced plasma insulin levels when compared with nondiabetic apoE(-/-) mice. Atherosclerotic lesions were significantly reduced in the D-4F-treated diabetic apoE(-/-) mice in whole aorta (1.11 ± 0.73 vs. 0.58 ± 0.44, percentage of whole aorta, P < 0.01) and in aortic roots (36,038 ± 18,467 μm²/section vs. 17,998 ± 12,491 μm²/section, P < 0.01) when compared with diabetic apoE(-/-) mice that did not receive D-4F. Macrophage content in atherosclerotic lesions from D-4F-treated diabetic apoE(-/-) mice was significantly reduced when compared with nontreated animals (78.03 ± 26.1 vs. 29.6 ± 15.2 P < 0.001, percentage of whole plaque). There were no differences in glucose, insulin, total cholesterol, HDL cholesterol, and triglyceride levels between the two groups. Arachidonic acid, PGE₂, PGD₂, 15-HETE, 12-HETE, and 13-HODE concentrations were significantly increased in the liver tissue of diabetic apoE(-/-) mice compared with nondiabetic apoE(-/-) mice and significantly reduced by D-4F treatment.ConclusionsOur results suggest that oral D-4F can prevent atherosclerosis development in pre-existing diabetic mice and this is associated with a reduction in hepatic arachidonic acid and oxidized fatty acid levels

Accelerated phosphatidylcholine turnover in macrophages promotes adipose tissue inflammation in obesity.

White adipose tissue (WAT) inflammation contributes to the development of insulin resistance in obesity. While the role of adipose tissue macrophage (ATM) pro-inflammatory signalling in the development of insulin resistance has been established, it is less clear how WAT inflammation is initiated. Here, we show that ATMs isolated from obese mice and humans exhibit markers of increased rate of de novo phosphatidylcholine (PC) biosynthesis. Macrophage-specific knockout of phosphocholine cytidylyltransferase A (CCTα), the rate-limiting enzyme of de novo PC biosynthesis pathway, alleviated obesity-induced WAT inflammation and insulin resistance. Mechanistically, CCTα-deficient macrophages showed reduced ER stress and inflammation in response to palmitate. Surprisingly, this was not due to lower exogenous palmitate incorporation into cellular PCs. Instead, CCTα-null macrophages had lower membrane PC turnover, leading to elevated membrane polyunsaturated fatty acid levels that negated the pro-inflammatory effects of palmitate. Our results reveal a causal link between obesity-associated increase in de novo PC synthesis, accelerated PC turnover and pro-inflammatory activation of ATMs