Failure Analysis of Variably Sized 4340 Steel Mandrels Utilized in the Production of Seamless Superalloy Rings through the Vertical Ring Rolling Process

Vertical ring rolling is a forging process which forms seamless metal rings through applying a large force at elevated temperatures onto component materials stabilized by cylindrical mandrels. Carlton Forge Works, a company which produces rings of superalloy materials such as INCO718 and 718Plus, is experiencing a consistent failure of mandrels due to extreme conditions. An analysis of the lifetime (bulk material, heat treatment, and use) was performed, which aided in the identification of process variables tied to mandrel failure. Experiments were formed surrounding three variables of the mandrel heat treatment: Austenitization temperature, quenching temperature, and tempering conditions, with the goal of analyzing the degradation of mandrels prior to failure with hardness measurements. Rockwell Hardness C (HRC) was used in each of the three experiments. The first experiment assessed incomplete austenitization due to overcrowded furnaces at 1400˚F and 1550˚F. Secondly, quenching for 10 minutes at 70˚F, 100˚F and 150˚F, was performed to simulate quench vat conditions. Finally, extra tempering at 300˚F, 400˚F, 500˚F, 570˚F, 700˚F, 900˚F and 1400˚F was performed to replicate over-tempering of the mandrels during rolling. Hardness degradation below the HRC range of superalloy rings (35-40 HRC) was used to numerically fit the lifetime of components and propose solutions for mandrel failure

A Square Facing the Water: Brunelleschi as an "Urban" Architect and the Project for Santo Spirito in Florence

openQuesta tesi tratta della figura e della vita del celebre architetto fiorentino Filippo Brunelleschi, con focus particolare sulla sua attività architettonica volta all'organizzazione urbana del quartiere di Santo Spirito e sul progetto originale che ne voleva piazza e chiesa affacciate sull'Arno. In questo elaborato si vogliono inoltre proporre alcuni modelli di riferimento ai quali Brunelleschi potrebbe essersi ispirato; fra questi Roma, Pisa, Venezia e i territori malatestiani

Painting the war: the intentions and motivations of the official Australian War Art Scheme of the First World War

Thesis (B.A.(Hons.)) -- University of Adelaide, School of History and Politics, Discipline of History, 2009

Pleistocene vertical carbon isotope and carbonate gradients in the South Atlantic sector of the Southern Ocean

We demonstrate that the carbon isotopic signal of mid-depth waters evolved differently from deep waters in the South Atlantic sector of the Southern Ocean during the Pleistocene. Deep sites (>3700 m) exhibit large glacial-to-interglacial variations in benthic d13C, whereas the amplitude of the d13C signal at Site 1088 (2100 m water depth) is small. Unlike the deep sites, at no time during the Pleistocene were benthic d13C values at Site 1088 lower than those of the deep Pacific. Reconstruction of intermediate-todeep d13C gradients (D13CI-D) supports the existence of a sharp chemocline between 2100 and 2700 m during most glacial stages of the last 1.1 myr. This chemical divide in the glacial Southern Ocean separated well-ventilated water above 2500 m from poorly ventilated water below. The D13CI-D signal parallels the Vostok atmospheric pCO2 record for the last 400 kyr, lending support to physical models that invoke changes in Southern Ocean deep water ventilation as a mechanism for changing atmospheric pCO2. The emergence of a strong 100-kyr cycle in D13CI-D during the mid-Pleistocene supports a change in vertical fractionation and deep-water ventilation rates in the Southern Ocean, and is consistent with possible CO2- forcing of this climate transition. Components: 7562 words, 14 figures, 2 tables

A dynamic view on work-related perfectionism: Antecedents at work and implications for employee well-being

Little is known about the role of perfectionism in employees' daily work. Our study aimed to provide a fine-grained view on perfectionism in work life by examining daily work-related perfectionism in terms of perfectionistic strivings and concerns. Drawing on whole trait theory and the principle of trait activation, we investigated experienced time pressure and criticism at work as antecedents of daily work-related perfectionism and in turn its implications for vigour and negative affect. In the course of two working weeks, 72 employees completed surveys three times per day, resulting in a total of 461 days of data. Multilevel path modelling showed that daily time pressure was positively related to both perfectionistic strivings and concerns, and that criticism was positively related to perfectionistic concerns. Daily work-related perfectionistic strivings were positively indirectly related to vigour at bedtime via vigour at the end of the workday. Daily work-related perfectionistic concerns were positively indirectly related to bedtime negative affect via end-of-workday negative affect. Our study shows that employees' daily experiences at work relate to within-person fluctuations in work-related perfectionism, which in turn matter for well-being both at work and at home. We conclude that a dynamic view broadens the understanding of perfectionism at work

Atlantic Ocean thermohaline circulation changes on orbital to suborbital timescales during the mid-Pleistocene

Mid-Pleistocene benthic ∂18O and ∂13C time series from the North Atlantic site 983 and Ceara Rise site 928 are compared to an array of existing isotopic records spanning the Atlantic basin and the geographic extremes of the North Atlantic Deep Water/Southern Ocean Water interface during both glacial and interglacial periods. This comparison allows the persistent millennial-scale intermediate depth North Atlantic ventilation changes recorded at site 983 to be placed within the context of the longer period water mass reorganizations taking place throughout the mid-Pleistocene. Our benthic ∂13C results suggest that the intermediate depth North Atlantic experienced millennial-scale changes in ventilation throughout the mid-Pleistocene climate shift. The times of poorest ventilation (low benthic ∂13C) persisted for only a few millennia and were associated with rapid decreases in benthic ∂18O, suggesting that ice sheet decay and melt water induced salinity changes were effective at throttling deep water production in the North Atlantic throughout the mid-Pleistocene. Similar but less pronounced decreases in the ∂13C of the middepth waters also punctuated interglacials, suggesting that large ice sheet fluctuations do not explain all of the observed thermohaline circulation mode shifts in the North Atlantic. Meanwhile, on orbital timescales, glacial deep to intermediate water ∂13C gradients evolved after ~0.95 Ma. Taken together, these observations provide a number of new constraints for understanding the timing and evolution of deep water circulation changes across the mid-Pleistocene

VIGIL NCIA E DESENVOLVIMENTO NA VIDA PANDÊMICA: IMPRESSÕES PRELIMINARES

Este artigo debruça-se sobre as repercussões da pandemia de coronavírus (COVID-19) na sociedade, dando enfoque ao emprego de novas tecnologias para a governabilidade de populações, combinando uma abordagem criminológica das técnicas de controle, com alicerces do desenvolvimento sustentável, para pôr em questão os modos de vida que nos conduziram até este precipício. Conclui-se que ao invés de desenvolvermos tecnologias examinativas aos motivos da crise vivida, vemos a naturalização de dispositivos de controle que não colocam em xeque as reais causas da pandemia. Para tanto é feito uso de material bibliográfico. Adota-se os métodos dedutivo e intuitivo

North Atlantic Intermediate to Deep Water circulation and chemical stratification during the past 1 Myr

Benthic foraminiferal carbon isotope records from a suite of drill sites in the North Atlantic are used to trace variations in the relative strengths of Lower North Atlantic Deep Water (LNADW), Upper North Atlantic Deep Water (UNADW), and Southern Ocean Water (SOW) over the past 1 Myr. During glacial intervals, significant increases in intermediate-to-deep δ13C gradients (commonly reaching >1.2‰) are consistent with changes in deep water circulation and associated chemical stratification. Bathymetric δ13C gradients covary with benthic foraminiferal δ18O and covary inversely with Vostok CO2, in agreement with chemical stratification as a driver of atmospheric CO2 changes. Three deep circulation indices based on δ13C show a phasing similar to North Atlantic sea surface temperatures, consistent with a Northern Hemisphere control of NADW/SOW variations. However, lags in the precession band indicate that factors other than deep water circulation control ice volume variations at least in this band