Analytical Computation of End-Coil Leakage Inductance of Round-Rotor Synchronous Machines Field Winding

3noThe computation of end coil leakage inductances of electric machines is a challenging task due to the complicated leakage flux 3D distribution in the winding overhang region. In this paper the problem is addressed of computing the field circuit leakage inductance of round-rotor synchronous machines. The proposed method is fully analytical and descends from the symbolical solution of Neumann integrals applied to the computation of self and mutual inductances combined with the method of mirror images to account for core effects. With respect to existing analytical approaches, the methodology requires neither numerical integral solutions nor discretizing the end-coil geometry into small straight elements. The accuracy of the proposed technique for computing the mutual inductance between two single end turns is assessed against measurements on a dedicated experimental set-up. The extension of the method to the computation of the entire field-circuit end-coil leakage inductance is assessed by comparison with 3D finite element analysis (FEA).Pubblicato online nel settembre 2015 e pubblicato su carta nel febbraio 2016partially_openopenBortolozzi, Mauro; Tessarolo, Alberto; Bruzzese, ClaudioBortolozzi, Mauro; Tessarolo, Alberto; Bruzzese, Claudi

VARIABILITY of EMISSION RATE DEFINITION in REGULATORY ODOUR DISPERSION MODELLING from CIVIL WASTEWATER TREATMENT PLANTS

The analysis of odour impacts in civil wastewater treatment plants (WWTPs) is a challenging task. Odour regulations still present a lack of standardization, that bring inherent levels of uncertainty to the analysis procedure. Dispersion models can provide support towards the characterization and reduction of odour nuisances. The application of dispersion models requires an adapt setting and a detailed characterization of the emission sources, in terms of emission rate. In this study odour dispersion of a large WWTP in northern Italy was considered. Simulations were carried out with the CALPUFF model. The study focused on the selection of the open field correction method for wind velocity used in the calculation of odour emission rates (OERs). Three different relationships were considered: the power law, the logarithmic law and the Deaves–Harris (D–H) law. The area underlying the 1 OU/m3, 3 OU/m3, and 5 OU/m3 concentration isopleths was considered as indicator. The results showed that OERs and impact area varied depending on the selected method. Taking the power law as the reference, the average variability of the impact area was between –33% and –48% if the logarithmic law was applied, and –83% and –94% if the D–H law was applied. The present study provides knowledge towards a better alignment of the concept of the odour impact criteria

Randomised clinical trial: a Lactobacillus GG and micronutrient-containing mixture is effective in reducing nosocomial infections in children, vs. placebo

BACKGROUND: Nosocomial infections are a major public health issue and preventative strategies using probiotics and micronutrients are being evaluated. AIM: To investigate the efficacy of a mixture of Lactobacillus GG and micronutrients in preventing nosocomial infections in children. METHODS: A randomised, double-blind, placebo-controlled trial was conducted in hospitalised children. Children (6 months to 5 years of age) received Lactobacillus GG (6 × 10(9) CFU/day) together with vitamins B and C and zinc or placebo, for 15 days, starting on the first day of hospitalisation. The incidence of gastrointestinal and respiratory nosocomial infections after discharge was determined by follow-up telephone call at 7 days. After 3 months, another telephone call estimated the incidence of further infections during follow-up. RESULTS: Ninety children completed the follow-up. Of 19/90 children with a nosocomial infection (20%), 4/45 children (9%) were in the treatment group and 15/45 (33%) in the placebo group (P = 0.016). Specifically, 2/45 (4%) children in the treatment group vs. 11/45 (24%) children in the placebo group (P = 0.007) presented with diarrhoea. The duration of hospitalisation was significantly shorter in the treatment group (3.9 days ± 1.7 vs. 4.9 ± 1.2; P = 0.003). At the follow-up, a total of 11/45 (24.4%) children in the treatment group had at least one episode of infection compared to 22/45 (48.9%) in the placebo group (P = 0.016). CONCLUSION: A mixture containing Lactobacillus GG and micronutrients may reduce the incidence of nosocomial infections, supporting the hypothesis that this may represent a valid strategy to prevent nosocomial infections

Measurement of the two-photon absorption cross-section of liquid argon with a time projection chamber

This paper reports on laser-induced multiphoton ionization at 266 nm of liquid argon in a time projection chamber (LAr TPC) detector. The electron signal produced by the laser beam is a formidable tool for the calibration and monitoring of next-generation large-mass LAr TPCs. The detector that we designed and tested allowed us to measure the two-photon absorption cross-section of LAr with unprecedented accuracy and precision: sigma_ex=(1.24\pm 0.10stat \pm 0.30syst) 10^{-56} cm^4s{-1}.Comment: 15 pages, 9 figure