9,573 research outputs found

    Independent Orbiter Assessment (IOA): Assessment of the manned maneuvering unit

    Get PDF
    The results of the Independent Orbiter Assessment (IOA) of the Failure Modes and Effects Analysis (FMEA) and Critical Items List (CIL) are presented. The IOA effort first completed an analysis of the Manned Maneuvering Unit (MMU) hardware, generating draft failure modes and potential critical items. To preserve independence, this analysis was accomplished without reliance upon the results contain within the NASA FMEA/CIL documentation. The IOA results were then compared to the proposed Martin Marietta FMEA/CIL Post 51-L updates. A discussion of each discrepancy from the comparison is provided through additional analysis as required. These discrepancies were flagged as issues, and recommendations were made based on the FMEA data available at the time. The results of this comparison for the Orbiter MMU hardware are documented. The IOA product for the MMU analysis consisted of 204 failure mode worksheets that resulted in 95 potential critical items being identified. Comparison was made to the NASA baseline which consisted of 179 FMEAs and 110 CIL items. This comparison produced agreement on all 121 FMEAs which caused differences in 92 CIL items

    Improving the Functional Control of Aged Ferroelectrics using Insights from Atomistic Modelling

    Get PDF
    We provide a fundamental insight into the microscopic mechanisms of the ageing processes. Using large scale molecular dynamics simulations of the prototypical ferroelectric material PbTiO3, we demonstrate that the experimentally observed ageing phenomena can be reproduced from intrinsic interactions of defect-dipoles related to dopant-vacancy associates, even in the absence of extrinsic effects. We show that variation of the dopant concentration modifies the material's hysteretic response. We identify a universal method to reduce loss and tune the electromechanical properties of inexpensive ceramics for efficient technologies.Comment: 6 pages, 3 figure

    Independent Orbiter Assessment (IOA): Analysis of the atmospheric revitalization pressure control subsystem

    Get PDF
    The results of the Independent Orbiter Assessment (IOA) of the Failure Modes and Effects Analysis/Critical Items List (FMEA/CIL) are presented. The IOA approach features a top-down analysis of the hardware to determine failure modes, criticality, and potential critical items. To preserve independence, this analysis was accomplished without reliance upon the results contained within the NASA FMEA/CIL documentation. The independent analysis results corresponding to the Orbiter Atmospheric Revitalization and Pressure Control Subsystem (ARPCS) are documented. The ARPCS hardware was categorized into the following subdivisions: (1) Atmospheric Make-up and Control (including the Auxiliary Oxygen Assembly, Oxygen Assembly, and Nitrogen Assembly); and (2) Atmospheric Vent and Control (including the Positive Relief Vent Assembly, Negative Relief Vent Assembly, and Cabin Vent Assembly). The IOA analysis process utilized available ARPCS hardware drawings and schematics for defining hardware assemblies, components, and hardware items. Each level of hardware was evaluated and analyzed for possible failure modes and effects. Criticality was assigned based upon the severity of the effect for each failure mode

    Independent Orbiter Assessment (IOA): Assessment of the life support and airlock support systems, volume 1

    Get PDF
    The results of the Independent Orbiter Assessment (IOA) of the Failure Modes and Effects Analysis (FMEA) and Critical Items List (CIL) are presented. The IOA effort first completed an analysis of the Life Support and Airlock Support Systems (LSS and ALSS) hardware, generating draft failure modes and potential critical items. To preserve independence, this analysis was accomplished without reliance upon the results contained within the NASA FMEA/CIL documentation. The IOA results were then compared to the NASA FMEA/CIL baseline with proposed Post 51-L updates included. The discrepancies were flagged for potential future resolution. This report documents the results of that comparison for the Orbiter LSS and ALSS hardware. The IOA product for the LSS and ALSS analysis consisted of 511 failure mode worksheets that resulted in 140 potential critical items. Comparison was made to the NASA baseline which consisted of 456 FMEAs and 101 CIL items. The IOA analysis identified 39 failure modes, 6 of which were classified as CIL items, for components not covered by the NASA FMEAs. It was recommended that these failure modes be added to the NASA FMEA baseline. The overall assessment produced agreement on all but 301 FMEAs which caused differences in 111 CIL items

    Use of unnamed sources drops from peak in 1960s and 1970s

    Get PDF
    © 2011, SAGE Publications Ltd. All rights reserved. This content analysis of The Washington Post and The New York Times finds that the use of anonymous sources peaked in the 1960s and 1970s. The analysis also finds that contemporary journalists are more likely to explain the reason for anonymity

    Fragmented skeletonised remains: Paget’s disease as a method of biological profiling using radiography

    Get PDF
    Background: This study presents the incidental finding of Paget’s disease within archaeological skeletal remains using radiography. The remains of a late medieval (14th-15th century AD) adult male were excavated in 2017 from St Albans Monks’ Graveyard, Hertfordshire, United Kingdom. Upon visual inspection the skeleton exhibited widespread changes suggestive of Paget’s disease which prompted the radiographic investigation. The resultant imaging demonstrated an expanded bone and coarse trabecular patterns characteristic of the pathology. Discussion: Forensic radiography provides valuable information for the reconstruction of biological profiles of the deceased for victim identification. Characteristic medical conditions such as Paget’s disease aid identification by excluding unaffected persons, as the pathology exhibits a higher prevalence among British white males of advanced age. This example, although archaeological in origin, illustrates how data available from human skeletal remains can be leveraged through radiographic imaging to glean biographical information which might otherwise be unavailable. In the presence of fragmentary skeletal remains, and the absence of DNA profiling, pathologies with characteristic radiographic appearances could be of forensic significance. Conclusion: This example demonstrates the radiographic appearances of Paget’s disease on fragmentary skeletal remains which may aid victim identification efforts. Consideration must be given to the limitations of Paget’s disease including anthropological estimations and the potential for alternative diagnoses. Lastly, radiography may offer an accurate, permanent record of the deceased as secondary evidence for identification efforts
    • …
    corecore