4,713 research outputs found

    In-Flight Performance of the Terminator Tape End-of-Life Deorbit Module

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    The Terminator Tape™ is a passive deorbit module that utilizes both electrodynamic and aerodynamic drag effects to reduce spacecraft deorbit time. To date, three satellites have deployed Terminator Tapes, accumulating a total flight time of approximately thirty months. The first two deployments, on the NPSAT-1 and PROX-1 satellites, are starting multi-year deorbit profiles that will characterize Terminator Tape performance over a full solar cycle as they descend from altitudes above 700km. Additionally, the DRAGRACER mission recently demonstrated performance at lower altitudes, where aerodynamic drag becomes the dominant effect and has given insight into late-stage performance of the tape. Analysis of the impact of the drag tape solution on the overall probability of collision with active satellites indicates the Terminator Tape can significantly reduce collision risks relative to an unaided passive decay approach

    Product to process lifecycle management in assembly automation systems

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    Presently, the automotive industry is facing enormous pressure due to global competition and ever changing legislative, economic and customer demands. Product and process development in the automotive manufacturing industry is a challenging task for many reasons. Current product life cycle management (PLM) systems tend to be product-focussed. Though, information about processes and resources are there but mostly linked to the product. Process is an important aspect, especially in assembly automation systems that link products to their manufacturing resources. This paper presents a process-centric approach to improve PLM systems in large-scale manufacturing companies, especially in the powertrain sector of the automotive industry. The idea is to integrate the information related to key engineering chains i.e. products, processes and resources based upon PLM philosophy and shift the trend of product-focussed lifecycle management to process-focussed lifecycle management, the outcome of which is the Product, Process and Resource Lifecycle Management not PLM only

    Allometry of Kinematics and Energetics in Carpenter Bees (Xylocopa Varipuncta) Hovering in Variable-Density Gases

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    We Assessed the Energetic and Aerodynamic Limits of Hovering Flight in the Carpenter Bee Xylocopa Varipuncta. using Normoxic, Variable-Density Mixtures of O2, N2 and He, We Were Able to Elicit Maximal Hovering Performance and Aerodynamic Failure in the Majority of Bees Sampled. Bees Were Not Isometric Regarding Thorax Mass and Wing Area, Both of Which Were Disproportionately Lower in Heavier Individuals. the Minimal Gas Density Necessary for Hovering (MGD) Increased with Body Mass and Decreased with Relative Thoracic Muscle Mass. Only the Four Bees in Our Sample with the Highest Body Mass-Specific Thorax Masses Were Able to Hover in Pure Heliox. Wingbeat Frequency and Stroke Amplitude during Maximal Hovering Were Significantly Greater Than in Normodense Hovering, Increased Significantly with Body Mass during Normodense Hovering But Were Mass Independent during Maximal Hovering. Reserve Capacity for Wingbeat Frequency and Stroke Amplitude Decreased Significantly with Increasing Body Mass, Although Reserve Capacity in Stroke Amplitude (10-30%) Exceeded that of Wingbeat Frequency (0-8%). Stroke Plane Angle during Normodense Hovering Was Significantly Greater Than during Maximal Hovering, Whereas Body Angle Was Significantly Greater during Maximal Hovering Than during Normodense Hovering. Power Production during Normodense Hovering Was Significantly Less Than during Maximal Hovering. Metabolic Rates Were Significantly Greater during Maximal Hovering Than during Normodense Hovering and Were Inversely Related to Body Mass during Maximal and Normodense Hovering. Metabolic Reserve Capacity Averaged 34% and Was Independent of Body Mass. Muscle Efficiencies Were Slightly Higher during Normodense Hovering. the Allometry of Power Production, Power Reserve Capacity and Muscle Efficiency Were Dependent on the Assumed Coefficient of Drag (CD), with Significant Allometries Most Often at Lower Values of CD. Larger Bees Operate Near the Envelope of Maximal Performance Even in Normodense Hovering Due to Smaller Body Mass-Specific Flight Muscles and Limited Reserve Capacities for Kinematics and Power Production

    Machine utilisation and breaksdown modelling for measuring productivity using virtual engineering simulation modelling

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    Results accuracy and reliability of discrete event simulation (DES) models to predict the production line productivities are based on the unexpected breakdowns taken place by machine faults or human errors. Process modeller practices DES modelling to incorporate these breakdowns and corresponding mainte-nances up-to the machine level. But actually breakdowns are potentially taken place at process level com-ponents inside the machine/stations. Domains like Virtual Engineering (VE) allow user to emulate the ac-tual machine build from components using the CAD data and thus define the components level processes model exist inside the machine station. Therefore author came with idea to integrate VE and DES model up-to component level processes to get an improved simulation modelling to analyse the machines breakdowns for validating pre-build and after-build phases of machine development. Initially in this arti-cle it was proposed to produce an algorithm required to integrate and model the component–level DES model driven from the available emulated data models

    A Compact Semi-Lumped Tunable Complex Impedance Transformer

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    International audienceThis article describes the design and performance of a compact tunable impedance transformer. The structure is based on a transmission line loaded by varactor diodes. Using only two pairs of diodes, the circuit is very small with a total length of only λ/10. Both the frequency range and the load impedance can be tuned by varying the varactor bias voltages. Our design provides a tunable operating frequency range of ± 40% and an impedance match ranging from 20 Ω to 90 Ω at 0.8 GHz and from 30 Ω to 170 Ω at 1.5 GHz. In addition, a new approach that considers losses for the simulation and measurement of this impedance transformer was investigated. The measured performance of a 1 GHz prototype design confirmed the validity of this new approach

    TF-CBT Training Augmented with a Self-Care Focus: Understanding Facilitators and Barriers to Treatment Implementation.

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    Clinicians working with youth exposed to trauma may be at increased risk for experiencing elevated levels of stress and symptoms of secondary traumatic stress, which can negatively impact clinician wellbeing and ultimately contribute to reduced access to quality care for clients. An innovative Trauma-Focused Cognitive Behavioral Therapy (TF-CBT) training incorporating self-care practices (i.e., Practice What You Preach; PWYP) was developed to help facilitate the implementation of TF-CBT and to enhance clinicians\u27 coping and decrease stress. The primary purpose of this study was to determine whether the PWYP-augmented training met three Objectives: (1) increase clinicians\u27 feelings of TF-CBT competency; (2) improve clinicians\u27 coping abilities/reduce clinicians\u27 stress; and (3) increase clinicians\u27 insight into the benefits and/or challenges clients may experience in treatment. An exploratory aim was also developed to identify additional facilitators and barriers of TF-CBT implementation. The written reflections of 86 community-based clinicians who participated in the PWYP-augmented TF-CBT training were examined using qualitative methods. The majority of clinicians indicated increased feelings of competency and improved coping abilities and/or stress levels; almost half mentioned increased insight into clients\u27 experiences. The most frequently mentioned additional facilitators were related to elements of the TF-CBT treatment model. Anxiety/self-doubt was the barrier most frequently mentioned, though all clinicians who mentioned this barrier indicated it lessened or resolved over the course of the training. Incorporating self-care strategies into trainings may serve as a facilitator for TF-CBT implementation by enhancing the competency and well-being of clinicians. The additional insights into barriers and facilitators can be used to further improve the PWYP initiative and future training and implementation efforts

    Challenges for creating magnetic fields by cosmic defects

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    We analyse the possibility that topological defects can act as a source of magnetic fields through the Harrison mechanism in the radiation era. We give a detailed relativistic derivation of the Harrison mechanism at first order in cosmological perturbations, and show that it is only efficient for temperatures above T ~ 0.2 keV. Our main result is that the vector metric perturbations generated by the defects cannot induce vorticity in the matter fluids at linear order, thereby excluding the production of currents and magnetic fields. We show that anisotropic stress in the matter fluids is required to source vorticity and magnetic fields. Our analysis is relevant for any mechanism whereby vorticity is meant to be transferred purely by gravitational interactions, and thus would also apply to dark matter or neutrinos.Comment: 9 pages, 1 figure; minor corrections and additions; accepted for publication in Physical Review

    Microstructure and texture analysis of δ-hydride precipitation in Zircaloy-4 materials by electron microscopy and neutron diffraction

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    This work presents a detailed microstructure and texture study of various hydrided Zircaloy-4 materials by neutron diffraction and microscopy. The results show that the precipitated δ-ZrH1.66 generally follows the δ (111) //α (0001) and δ[]//α[] orientation relationship with the α-Zr matrix. The δ-hydride displays a weak texture that is determined by the texture of the α-Zr matrix, and this dependence essentially originates from the observed orientation correlation between α-Zr and δ-hydride. Neutron diffraction line profile analysis and high-resolution transmission electron microscopy observations reveal a significant number of dislocations present in the δ-hydride, with an estimated average density one order of magnitude higher than that in the α-Zr matrix, which contributes to the accommodation of the substantial misfit strains associated with hydride precipitation in the α-Zr matrix. The present observations provide an insight into the behaviour of δ-hydride precipitation in zirconium alloys and may help with understanding the induced embrittling effect of hydrides.Fil: Wang, Zhiyang. University of Wollongong; Australia. Australian Nuclear Science and Technology Organisation; AustraliaFil: Garbe, Ulf. Australian Nuclear Science and Technology Organisation; AustraliaFil: Li, Huijun. University of Wollongong; AustraliaFil: Wang, Yanbo. University of Sydney; AustraliaFil: Studer, Andrew J.. Australian Nuclear Science and Technology Organisation; AustraliaFil: Sun, Guangai. Institute of Nuclear Physics and Chemistry, CAEP; ChinaFil: Harrison, Robert P.. Australian Nuclear Science and Technology Organisation, Institute of Materials Engineering; AustraliaFil: Liao, Xiaozhou. University of Sydney; AustraliaFil: Vicente Alvarez, Miguel Angel. Comisión Nacional de Energía Atómica. Gerencia del Área de Energía Nuclear. Instituto Balseiro; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Santisteban, Javier Roberto. Comisión Nacional de Energía Atómica. Gerencia del Área de Energía Nuclear. Instituto Balseiro; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Kong, Charlie. University of New South Wales; Australi

    Ex vivo renal perfusion and autotransplantation in treatment of calculous disease or abdominal aortic aneurysm.

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    Two more indications are described for temporary ex vivo perfusion of kidneys with revascularization of these organs as autografts to orthotopic or heterotopic locations. One of the patients had staghorn calculi which were removed from a solitary kidney. The other patient had both kidneys autografted in the course of a surgical procedure on an extensive abdominal aortic aneurysm
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