Failure Analyses of Two Gas Turbine Wheels

AbstractThe results of the analysis of the catastrophic failures of two high pressure turbine wheels are discussed in this study. Fractographic and metallographic analyses on both the wheel and a set of failed blades of both wheels were performed to determine the possible events that led to failure. Both wheel materials had an austenitic microstructure, while blade materials were different for each case. One blade material is similar to INCONEL 738 nickel-based superalloy, while the other study is a single-crystal with dendritic growth microstructure. Facing two failures with apparently similar characteristics, once fractographic and metallographic analysis were performed, it was proved that failure modes respond to quite different origins in each case. This led to different corrective actions, according to each particular main contributing factor

A 1-m Foucault pendulum rolling on a ball

We have built a short Foucault pendulum of 1-m length. The aim of this work was to increase the sensitivity to elliptical trajectories from other longer pendula. The design was a semi-rigid pendulum that rolls over a small ball. The measurements of the movements (azimuth and elliptical trajectory) were done by an optical method. The resulting pendulum works in a medium satisfactory way due to problems of the correct choice of the mass of the bob together with the diameter of the supporting ball. It is also important to keep the rolling surface very clean.Fil: Salva, Horacio Ramon. Comision Nacional de Energia Atomica. Gerencia del Area Investicaciones y Aplicaciones No Nucleares; Argentina;Fil: Benavides, R.E.. Comision Nacional de Energia Atomica. Gerencia D/area Invest y Aplicaciones No Nucleares. Gerencia de Fisica (cab). Grupo de Fisica de Metales; Argentina;Fil: Venturino, J. A.. Comision Nacional de Energia Atomica. Gerencia D/area Invest y Aplicaciones No Nucleares. Gerencia de Fisica (cab). Grupo de Fisica de Metales;Fil: Cuscueta, Diego Javier. Comision Nacional de Energia Atomica. Gerencia del Area Investicaciones y Aplicaciones No Nucleares; Argentina;Fil: Ghilarducci,. Comision Nacional de Energia Atomica. Gerencia del Area Investicaciones y Aplicaciones No Nucleares; Argentina

The Effect of Dietary Supplements on Endurance Exercise Performance and Core Temperature in Hot Environments: A Meta-analysis and Meta-regression

BackgroundThe ergogenic effects of dietary supplements on endurance exercise performance are well-established; however, their efficacy in hot environmental conditions has not been systematically evaluated.Objectives(1) To meta-analyse studies investigating the effects of selected dietary supplements on endurance performance and core temperature responses in the heat. Supplements were included if they were deemed to: (a) have a strong evidence base for ‘directly’ improving thermoneutral endurance performance, based on current position statements, or (b) have a proposed mechanism of action that related to modifiable factors associated with thermal balance. (2) To conduct meta-regressions to evaluate the moderating effect of selected variables on endurance performance and core temperature responses in the heat following dietary supplementation.MethodsA search was performed using various databases in May 2020. After screening, 25 peer-reviewed articles were identified for inclusion, across three separate meta-analyses: (1) exercise performance; (2) end core temperature; (3) submaximal core temperature. The moderating effect of several variables were assessed via sub-analysis and meta-regression.ResultsOverall, dietary supplementation had a trivial significant positive effect on exercise performance (Hedges’ g = 0.18, 95% CI 0.007–0.352, P = 0.042), a trivial non-significant positive effect on submaximal core temperature (Hedges’ g = 0.18, 95% CI − 0.021 to 0.379, P = 0.080) and a small non-significant positive effect on end core temperature (Hedges’ g = 0.20, 95% CI − 0.041 to 0.439, P = 0.104) in the heat. There was a non-significant effect of individual supplements on exercise performance (P = 0.973) and submaximal core temperature (P = 0.599). However, end core temperature was significantly affected by supplement type (P = 0.003), which was attributable to caffeine’s large significant positive effect (n = 8; Hedges’ g = 0.82, 95% CI 0.433–1.202, P < 0.001) and taurine’s medium significant negative effect (n = 1; Hedges’ g = − 0.96, 95% CI − 1.855 to − 0.069, P = 0.035).ConclusionSupplements such as caffeine and nitrates do not enhance endurance performance in the heat, with caffeine also increasing core temperature responses. Some amino acids might offer the greatest performance benefits in the heat. Exercising in the heat negatively affected the efficacy of many dietary supplements, indicating that further research is needed and current guidelines for performance in hot environments likely require revision

Migration paths saturations in meta-epidemic systems

In this paper we consider a simple two-patch model in which a population affected by a disease can freely move. We assume that the capacity of the interconnected paths is limited, and thereby influencing the migration rates. Possible habitat disruptions due to human activities or natural events are accounted for. The demographic assumptions prevent the ecosystem to be wiped out, and the disease remains endemic in both populated patches at a stable equilibrium, but possibly also with an oscillatory behavior in the case of unidirectional migrations. Interestingly, if infected cannot migrate, it is possible that one patch becomes disease-free. This fact could be exploited to keep disease-free at least part of the population

Glasgow Prognostic Score Class 2 Predicts Prolonged Intensive Care Unit Stay in Patients Undergoing Pneumonectomy

Background. The Glasgow prognostic score (GPS) is an inflammation-based score based on albuminemia and Creactive protein concentration proved to be associated with cancer-specific survival in several neoplasms. The present study explored the immediate postoperative value of the GPS for patients undergoing pneumonectomy for lung cancer. Methods. The value of the GPS preoperatively was studied in 250 patients undergoing pneumonectomy for non-small cell lung cancer (NSCLC). We analyzed overall postoperative complications, pulmonary and cardiac complications, 30-day postoperative death, reoperation for early complications, intensive care unit (ICU) length of stay and total length of hospital stay. Results. Patients with a GPS of 0 and 1 had a mean ICU length of stay of 0.8 days, whereas patients with a GPS of 2 had a mean ICU stay of 5.0 days (p = 0.004). The postoperative mortality rate in patients with a GPS of 2 was much higher than in patients with a GPS of 1 and 2, although it was not statistically significant (p = 0.083). Conclusions. A preoperative GPS of 2 effectively predicts a prolonged ICU stay in patients who undergo pneumonectomy for cancer. The score may be proposed as an easy-to-determine, economical, and fast preoperative tool to plan and optimize ICU admissions after elective pneumonectomy