1,466 research outputs found
Letter from T. B. Everitt to L. A. Ashley
No full textLetter from T. B. Everitt to L. A. Ashley advising him on starting negotiations with the Hughes Tool Company.https://mavmatrix.uta.edu/specialcollections_ivorydaviscivilrightscasepapers/1023/thumbnail.jp
Data for: Surface initiation of rolling contact fatigue at asperities considering slip, shear limit and thermal elastohydrodynamic lubrication
No full textData from a single asperity passing through a thermal elastohydrodynamic, TEHL, contact. The aim of the simulations is to clarify the loading conditions of asperities passing through thermal elastohydrodynamic lubricated contacts. The Figs 10 to 14 in C.-M. Everitts and B. Alfredssons article ‘Surface initiation of rolling contact fatigue at asperities considering slip, shear limit and thermal elastohydrodynamic lubrication’ was derived from the uploaded data. The numerical method used to obtain the data along with all input parameters used is presented in that article. The uploaded dataset contains two zip files containing data from one simulation each. The loading conditions were the same for both simulations except for the speed of the surfaces. In the first file, the speed of the surface with the asperity was 8 m/s while in the second zip file the speed of the asperity surface was 9 m/s. Note that the mean entrainment speed was 8.5 m/s in both simulations yielding different slip conditions for the two data sets.Each zip file contains the data from one TEHL-simulation divided into four separate results files. One data file contains the pressure, one the film thickness, one the temperature of the lubricant and the last the temperature of the metal body with the asperity. Each file contains the data from 3 steps where the grid size was gradually refined, then 10 steps when the time dependence was gradually introduced. Thereafter it is 514 time steps containing the information of the loading of the asperity as it passed through the TEHL contacts. Included in the folder is also a Matlab script reading and visualizing the data.The structure of the files is that the data from each simulation step is added after each other. For the pressure, the film thickness and the temperature of the lubricant each row represent the transverse direction and each column represents the rolling direction. The first row of each step contains the location of the nodes in the transverse direction and the first column contains the data of the nodes in the rolling direction. The structure of the metal temperature is such that each step contains the temperature of 39 layers. For each layer, the structure is the same as for the files mentioned before, with the rows representing the transverse direction and the columns the rolling direction, and the first row and column containing information about the node positions. For the spacing in the vertical direction, the reader is referred to the article ‘Surface initiation of rolling contact fatigue at asperities considering slip, shear limit and thermal elastohydrodynamic lubrication’ by C.-M. Everitt and B. Alfredsson
Developments in advanced high temperature disc and blade materials for aero-engine gas turbine applications
No full textThe research carried out as part of this EngD is aimed at understanding the high temperature materials used in modern gas turbine applications and providing QinetiQ with the information required to assess component performance in new propulsion systems. Performance gains are achieved through increased turbine gas temperatures which lead to hotter turbine disc rims and blades. The work has focussed on two key areas: (1) Disc Alloy Assessment of High Temperature Properties; and (2) Thermal Barrier Coating Life Assessment; which are drawn together by the overarching theme of the EngD: Lifing of Critical Components in Gas Turbine Engines.Performance of sub-solvus heat treated N18 alloy in the temperature range of 650°C to 725°C has been examined via monotonic and cyclically stabilised tensile, creep and strain controlled low cycle fatigue (LCF) tests including LCF behaviour in the presence of a stress concentration under load-control. Crack propagation studies have been undertaken on N18 and a particular super-solvus heat treatment variant of the alloy LSHR at the same temperatures, in air and vacuum with 1s and 20s dwell times. Comparisons between the results of this testing and microstructural characterisation with RR1000, UDIMET® 720 Low Interstitial (U720Li) and a large grain variant of U720Li have been carried out. In all alloys, strength is linked to a combination of ?' content and grain size as well as slow diffusing atoms in solid solution. High temperature strength improves creep performance which is also dependent on grain size and grain boundary character.Fatigue testing revealed that N18 had the most transgranular crack propagation with a good resistance to intergranular failure modes, with U720Li the most intergranular. Under vacuum conditions transgranular failure modes are evident to higher temperature and ?K, with LSHR failing almost completely by intergranular crack propagation in air. For N18 significant cyclic softening occurs at 725°C with LCF initiation occurring at pores and oxidised particles. An apparent activation energy technique was used to provide further insights into the failure modes of these alloys, this indicating that, for N18 with 1s dwell, changes in fatigue crack growth rates were attributed to static properties and for LSHR, with 20s dwell in air, that changes were attributed to the detrimental synergistic combination of creep and oxidation at 725°C. Microchemistry at grain boundaries, especially M23C6 carbides, plays an important role in these alloys.Failure mechanisms within a thermal barrier coating (TBC) system consisting of a CMSX4 substrate, PtAl bond coat, thermally grown oxide (TGO) layer and a top coat applied using electron beam physical vapour deposition have been considered. TGO growth has been quantified under isothermal, two stage temperature and thermal cyclic exposures. An Arrhenius relation was used to describe the TGO growth and produce an isothermal TGO growth model. The output from this was used in the QinetiQ TBC Lifing Model. Thermo-mechanical fatigue test methods were also developed including a novel thermocouple placement permitting substrate temperature to be monitored without disturbing the top coat such that the QinetiQ TBC Lifing Model could be validated.The importance of material, system specific knowledge and performance data with respect to a particular design space for critical components in gas turbine engines has been highlighted. Data and knowledge regarding N18, LSHR and TBC systems has been added to the QinetiQ’s databank enhancing their capability for providing independent advice regarding high temperature materials particularly in new gas turbine engines
Snowflake Fed/Pool
No full textThe elevator in the image is the Federal Elevator, constructed in 1962 from wood and equipment reclaimed from Federal Elevators in Fallison and Windygates that had been torn down. It became the new Snowflake Pool B Elevator (Manitoba Pool Elevators) in 1972 when the original Pool B Elevator was sold to a local farmer. The Pool B elevator ceased commercial operations in 1981. Source of History/Biography: "Portrait of a Grain Elevator: Snowflake, MB" in Canadiana - artist: Christopher Walker, researcher: Ed Ledohowski, editor: George Sayer Bain.Slide was in the possession of John Everitt before its donation to the SJ McKee Archives in 2007.Item is an image of the elevator at Snowflake, MB.John EverittOriginal order. Box 1 - Section Man Pool 1The use of images within the collection must include the following credit line: John Everitt collection, SJ McKee Archives, Brandon Universit
A micro-mechanistic approach to lifing of thermal barrier coatings for gas turbine blades
No full textA summary of progress made in micro-mechanistic approach to lifing of thermal barrier coatings for gas turbine blades. Aim is to develop a model for Thermal Barrier Coating lifetimes that predicts the physical changes occurring in terms of morphology and physical properties of the materials involved and combines these to predict failure lifetime under thermo-mechanical fatigue (TMF) conditions. A test matrix has been designed to isolate the effects of the various damage mechanisms and includes: (a) isothermal exposures, (b) Single step thermal exposures, (c) Thermal cyclic tests (d) a creep test and (e) TMF tests. The TMF testing uses a susceptor to produce representative temperature profiles as seen in service across the specimen. Initial results of the thickness of the Thermally Grown Oxide (TGO) layer are presented. A TMF test capability for TBCs that simulates conditions seen in service has been demonstrated
Snowflake Pool/Federal
No full textBoth elevators ceased commerical operations in 1981. Source of History/Biography: "Portrait of a Grain Elevator: Snowflake, MB" in Canadiana - artist: Christopher Walker, researcher: Ed Ledohowski, editor: George Sayer Bain.Slide was in the possession of John Everitt before its donation to the SJ McKee Archives in 2007.Item is an image of old Pool A and the new Pool B elevators at Snowflake, MB.John EverittOriginal order. Box 1 - Section Man Pool 1The use of images within the collection must include the following credit line: John Everitt collection, SJ McKee Archives, Brandon Universit
Killarney Pool
No full textPool B is a composite grain elevator built along the CPR by Manitoba Pool Elevators in 1960. It was renovated in the 1980s and demolished after 2007. The wooden UGG elevator, built in 1953, was demolished in September 2017. Source of History/Biography: http://www.mhs.mb.ca/docs/sites/killarneyelevator.shtml ; http://www.mhs.mb.ca/docs/sites/killarneyelevator2.shtmlSlide was in the possession of John Everitt before its donation to the SJ McKee Archives in 2007.Item is an image of the Manitoba Pool Elevator Pool B at Killarney, MB. A portion of the United Grain Growers elevator is visible in the foreground.John EverittOriginal order. Box 1 - Section Man Pool 1The use of images within the collection must include the following credit line: John Everitt collection, SJ McKee Archives, Brandon Universit
A Game-Theoretic Analysis of the Off-Switch Game
No full textThe off-switch game is a game theoretic model of a highly intelligent robot interacting with a human. In the original paper by Hadfield-Menell et al. (2016b), the analysis is not fully game-theoretic as the human is modelled as an irrational player, and the robot’s best action is only calculated under unrealistic normality and soft-max assumptions. In this paper, we make the analysis fully game theoretic, by modelling the human as a rational player with a random utility function. As a consequence, we are able to easily calculate the robot’s best action for arbitrary belief and irrationality assumptions.This work was in part supported by ARC grant DP15010459
Double Dissociation of the Requirement for GluN2B- and GluN2A- Containing NMDA Receptors in the Destabilization and Restabilization of a Reconsolidating Memory
No full textSignaling at NMDA receptors (NMDARs) is known to be important for memory reconsolidation, but while most studies show that NMDAR antagonists prevent memory restabilization and produce amnesia, others have shown that GluN2B-selective NMDAR antagonists prevent memory destabilization, protecting the memory. These apparently paradoxical, conflicting data provide an opportunity to define more precisely the requirement for different NMDAR subtypes in the mechanisms underlying memory reconsolidation and to further understand the contribution of glutamatergic signaling to this process. Here, using rats with fully consolidated pavlovian auditory fear memories, we demonstrate a double dissociation in the requirement for GluN2B-containing and GluN2A-containing NMDARs within the basolateral amygdala in the memory destabilization and restabilization processes, respectively. We further show a double dissociation in the mechanisms underlying memory retrieval and memory destabilization, since AMPAR antagonism prevented memory retrieval while still allowing the destabilization process to occur. These data demonstrate that glutamatergic signaling mechanisms within the basolateral amygdala differentially and dissociably mediate the retrieval, destabilization, and restabilization of previously consolidated fear memories
Newdale
No full textThe central elevator in the image is Manitoba Pool Elevator Pool B, built in 1951. The annex on the right, formerly Pool C, was a former Lake of the Woods Milling Co. elevator built in 1925 and purchased by MPE in 1959. MPE moved it to the Newdale site in late 1979, at which point it was converted into an annex; the crib annex on the left of the image was built around the same time. The Pool B elevator was closed by Agricore in 2001 and demolished in 2004. Source of History/Biography: http://www.mhs.mb.ca/docs/sites/sidneyelevator.shtmlSlide was in the possession of John Everitt before its donation to the SJ McKee Archives in 2007.Item is an image of the Agricore (formerly MPE) elevator and annexes at Newdale, MB. Also known as the Reliance Grain Elevator.John EverittOriginal order. Box 1 - Section Man Pool 1The use of images within the collection must include the following credit line: John Everitt collection, SJ McKee Archives, Brandon Universit
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