Analisi e ottimizzazione del progetto di uno stadio di conversione a media frequenza per trazione ferroviaria

Il lavoro esposto in questa tesi è consistito in due fasi, la prima, che potremmo chiamare di modellizzazione circuitale, dove si è andati a modellizzare le linee di trazione ferroviaria in AC, gli IGBT, il trasformatore e tutti gli altri blocchi basi necessari al funzionamento. Durante la seconda fase si è simulato effettivamente il circuito di trazione, e lo si è reso conforme alle normative che regolano le interferenze condotte per i sistemi di trazione in AC. Il Controllo implementato sugli IGBT del convertitore DC-DC impone un periodo in cui gli IGBT sono entrambi spenti, questo provoca l’introduzione sulla tensione del carico di componenti frequenziali non volute. Naturalmente il controllo PWM che è stato implementato per gli IGBT dei convertitori 4QC, ha permesso di ottenere risultati conformi con quelli che erano stati prefissati, nulla vieta però in un futuro lavoro, di cercare nuove strategie di controllo ed implementarle nel sistema. Anche perché nell’ultimo capitolo l’ottimizzazione che è stata fatta, è stata quella di ridurre le componenti frequenziali indesiderate immesse sulla linea mediante filtri notch. Questa architettura, invece, può essere implementata avendo costi inferiori, su locomotive che funzionano su sistemi alimentati a 15 kV 16 2/3 Hz

A comprehensive study for the validation of a LC/MS/MS method for the determination of free and total forms of urinary cortisol and its metabolites

Several pathological conditions can be related to the alteration of the urinary levels of cortisol (F) and itsmetabolites. The determination of each of them in the free and free plus conjugated form can provide adeeper insight into the impaired activity of the cortisol metabolism enzymes, thus improving the diag-nosis protocol currently based only on the determination of total amount of urinary cortisol metabolites.In that view, an LC–MS/MS method for the determination of the free and total amount of urinary F, cor-tisone (E), tetrahydrocortisol (THF), allo-tetrahydrocortisol (A-THF) and tetrahydrocortisone (THE) wasthus developed and validated. Deconjugation of glucocorticoids was carried out by enzymatic hydroly-sis. Analytes were extracted by solid phase extraction, separated by liquid chromatography and analyzedvia electro-spray ionization (negative ion mode) triple-quadrupole mass spectrometry in the selectedreaction monitoring mode using a stable isotope-labeled internal standard.Baseline separation for all compounds, in particular the two stereoisomers A-THF and THF, wasobtained. Matrix effects, not reported so far, were observed and minimized for the determination ofurinary free E and THE. Validated range was 0.5–1000 ng/mL for A-THF and THF, 5–800 ng/mL for E andTHE and 1–1000 ng/mL for F, with R2values greater than 0.9981. The LOD and LOQ of the describedmethod ranged from 0.1 to 3.0 ng/mL, while the extraction recoveries resulted close to 100% for all theglucocorticoids determined. Precision and accuracy were well within ±10%. As suggested by the resultsobtained in the preliminary study on polycystic ovary syndrome (PCOS) urine samples, the method canbe used to support clinical diagnosis of pathologies related to cortisol metabolism. In fact, levels of freeand total glucocorticoids in control subjects were in agreement with previously reported data, as well asfree and total A-THF/THF ratio in PCOS patients. Conversely, in the latter free F/E and A-THF + THF/THEratios were lower than in control subjects (P < 0.01), suggesting a possible alteration of 11-HSD1 and11-HSD2 activity, to be further investigated

Synthesis, x-ray structure and anion binding properties of a cryptand-like hybrid calixpyrrole

The novel cryptand in/out-3, containing two tripyrrolemethane units briged by three 1,3- diisopropylidenbenzene arms was readily synthesized by a convergent three-step synthesis. It binds fluoride by inclusion with excellent selectivity with respect to a number of other tested anions. The structure of the free receptor and that of its fluoride complex were investigated in solution by NMR spectroscopy. The solid state X-ray structure of the free cryptand 3 was also determined

An investigation on drag reduction for axisymmetric bodies

This thesis, carried out in collaboration with the Queen Mary University of London, has the aim of study drag reduction devices for axisymmetric bodies using both experiments on wind tunnel and numerical flow simulations. Models used for wind tunnel experiments were a 4:1 ellipsoid, with the possibility to replace the rear section with a conic boat tail and a 4:1 prolate ellipsoid; this last model was equipped with an internal fan and modified with an intake at the rear for wake aspiration and a conic mid-section in order to perform boundary layer blowing from an annular slot. Results show how the presence of a conic boat tail lead to a reduction of the form drag and boundary layer suction/wake aspiration have great impact on reducing both viscous and form drag. In this latter case it is suggested, as a future development, a study of the ratio between power saved from the drag reduction and power used by active drag reducing device. CFD main result is that the numerical predictions are capable to follow the experimental trend just with K-Omega SST turbulence model

Unique Associations between Insulin-Like Growth Factor Binding Protein-1, Insulin-Like Growth Factor-1 and T Cell Immunoglobulin Mucin 3 in Successful Twin Pregnancies Conceived with Donor Oocytes

Background and Objectives: To investigate if pregnancies conceived using an oocyte donor necessitate an alteration in immune regulation, we compared concentrations of insulin-like growth factor binding protein (IGFBP)-1, insulin-like growth factor (IGF)-1 and T cell immunoglobulin mucin-3 (Tim-3) in women with ongoing successful twin pregnancies conceived spontaneously, using assisted reproductive technologies that utilized homologous oocytes or with donor oocytes. Differences in levels of these immune modulatory proteins may be magnified and easier to detect in twin as compared to singleton pregnancies. Methods: In this prospective study IGFBP-1 and IGF-1 were measured in sera and Tim-3 in lysates of peripheral blood mononuclear cells (PBMCs) by ELISA. Results: Median IGFBP-1 levels were lower in women with donor oocytes (41.4 ng/ml) as compared to those with a spontaneous conception (51.2 ng/mL) or who conceived with various assisted reproduction protocols using homologous oocytes (52.4 ng/mL) (p &lt; 0.001). IGF-1 and Tim-3 levels were comparable in each group. The IGFBP-1 level was inversely correlated to the IGF-1 concentration only in women with donor oocytes (p = 0.032). IGFBP-1 and Tim-3 levels were similarly negatively correlated in the donor oocyte group (p = 0. 012). Women in the assisted reproduction group who conceived following intracytoplasmic sperm injection were the only other group in which IGFBP-1 and Tim-3 were negatively correlated (p = 0.018). Conclusions: Down-regulation of IGFBP-1 production in pregnancies conceived with donor oocytes may reduce the extent of pro-inflammatory immunity and contribute to successful outcome in totally allogeneic pregnancies

Neonatal Hypersusceptibility to Endotoxin Correlates with Increased Tumor Necrosis Factor Production in Mice

Septic shock is a major cause of mortality in neonates. The hypothesis was tested that neonatal, age is associated with altered sensitivity to shock-inducing bacterial products or proinflammatory, cytokines (or both). Mice of different ages were inoculated with various doses of lipopolysaccharide, (LPS), superantigenic staphylococcal enterotoxin B (SEB), or recombinant tumor necrosis factor-α, (rTNF-α), alone or in combination with the sensitizing agent D-galactosamine. Neonatal mice were, markedly more susceptible to LPS-induced lethality but more resistant to SEB than were adults (P, \u3c .05). Mice of different ages did not differ, however, in their sensitivity to lethal activities of rTNFα. Neonatal susceptibility to LPS and SEB correlated directly with plasma TNF-α but not IFN-γ, levels, which was confirmed by TNF-α and IFN-γ blockade experiments. These data document, marked age-related differences in the pathophysiology of septic shock and suggest that IFN-γ is, not an obligatory mediator of either LPS- or SEB-induced lethality in neonates

Manufacturing of PAV-ONE, a Permeator against Vacuum Mock-Up with Niobium Membrane

The Permeator Against Vacuum (PAV) is one of the proposed technologies for the Tritium Extraction System of the WCLL BB (Water-Cooled Lithium-Lead Breeding Blanket) of the EU DEMO reactor. In this paper, the manufacturing of the first PAV mock-up with a niobium membrane with a cylindrical configuration is presented. This work aimed to demonstrate the possibility of manufacturing a relevant-size PAV to be later tested in the TRIEX-II facility. The adopted prototypical solutions are described in detail, starting with the methodology developed to join the Nb tubes with a 10CrMo9-10 (A182 F22) plate. Dedicated manufacturing and welding procedures, based on vacuum brazing with a nickel-based brazing alloy, were developed to solve the problem. This new kind of brazing was first analyzed to check the morphology of the joint and then tested to check its capability to withstand the TRIEX-II operative conditions. In parallel, the compatibility with a lithium-lead environment was analyzed by exposing samples of niobium and 10CrMo9-10 (A335 P22) to a flow of the eutectic alloy at 500 °C up to 4000 h. Finally, the PAV mock-up was installed in the TRIEX-II facility