12,333 research outputs found

    High-Throughput Classification of Radiographs Using Deep Convolutional Neural Networks.

    Get PDF
    The study aimed to determine if computer vision techniques rooted in deep learning can use a small set of radiographs to perform clinically relevant image classification with high fidelity. One thousand eight hundred eighty-five chest radiographs on 909 patients obtained between January 2013 and July 2015 at our institution were retrieved and anonymized. The source images were manually annotated as frontal or lateral and randomly divided into training, validation, and test sets. Training and validation sets were augmented to over 150,000 images using standard image manipulations. We then pre-trained a series of deep convolutional networks based on the open-source GoogLeNet with various transformations of the open-source ImageNet (non-radiology) images. These trained networks were then fine-tuned using the original and augmented radiology images. The model with highest validation accuracy was applied to our institutional test set and a publicly available set. Accuracy was assessed by using the Youden Index to set a binary cutoff for frontal or lateral classification. This retrospective study was IRB approved prior to initiation. A network pre-trained on 1.2 million greyscale ImageNet images and fine-tuned on augmented radiographs was chosen. The binary classification method correctly classified 100 % (95 % CI 99.73-100 %) of both our test set and the publicly available images. Classification was rapid, at 38 images per second. A deep convolutional neural network created using non-radiological images, and an augmented set of radiographs is effective in highly accurate classification of chest radiograph view type and is a feasible, rapid method for high-throughput annotation

    Environmental effects on lunar astronomical observatories

    Get PDF
    The Moon offers a stable platform with excellent seeing conditions for astronomical observations. Some troublesome aspects of the lunar environment will need to be overcome to realize the full potential of the Moon as an observatory site. Mitigation of negative effects of vacuum, thermal radiation, dust, and micrometeorite impact is feasible with careful engineering and operational planning. Shields against impact, dust, and solar radiation need to be developed. Means of restoring degraded surfaces are probably essential for optical and thermal control surfaces deployed in long-lifetime lunar facilities. Precursor missions should be planned to validate and enhance the understanding of the lunar environment (e.g., dust behavior without and with human presence) and to determine environmental effects on surfaces and components. Precursor missions should generate data useful in establishing keepout zones around observatory facilities where rocket launches and landings, mining, and vehicular traffic could be detrimental to observatory operation

    Environmental effects on an optical-UV-IR synthesis array

    Get PDF
    The Moon offers a stable platform with excellent seeing conditions for the Lunar Optical-UV-IR Synthesis Array (LOUISA). Some troublesome aspects of the lunar environment will need to be overcome to realize the full potential of the Moon as an observatory site. Mitigation of negative effects of vacuum, thermal radiation, dust, and micrometeorite impact is feasible with careful engineering and operational planning. Shields against impact, dust, and solar radiation need to be developed. Means of restoring degraded surfaces are probably essential for optical and thermal control surfaces deployed in long-lifetime lunar facilities. Precursor missions should be planned to validate and enhance the understanding of the lunar environment (e.g., dust behavior without and with human presence and to determine environmental effects on surfaces and components. Precursor missions should generate data useful in establishing keepout zones around observatory facilities while rocket launches and landings, mining, and vehicular traffic could be detrimental to observatory operation

    Internal performance of a hybrid axisymmetric/nonaxisymmetric convergent-divergent nozzle

    Get PDF
    An investigation was conducted in the static test facility of the Langley 16-foot transonic tunnel to determine the internal performance of a hybrid axisymmetric/nonaxisymmetric nozzle in forward-thrust mode. Nozzle cross-sections in the spherical convergent section were axisymmetric whereas cross-sections in the divergent flap area nonaxisymmetric (two-dimensional). Nozzle concepts simulating dry and afterburning power settings were investigated. Both subsonic cruise and supersonic cruise expansion ratios were tested for the dry power nozzle concepts. Afterburning power configurations were tested at an expansion ratio typical for subsonic acceleration. The spherical convergent flaps were designed in such a way that the transition from axisymmetric to nonaxisymmetric cross-section occurred in the region of the nozzle throat. Three different nozzle throat geometries were tested for each nozzle power setting. High-pressure air was used to simulate jet exhaust at nozzle pressure ratios up to 12.0

    Static investigation of a two-dimensional convergent-divergent exhaust nozzle with multiaxis thrust-vectoring capability

    Get PDF
    An investigation was conducted in the Static Test Facility of the NASA Langley 16-Foot Transonic Tunnel to determine the internal performance of two-dimensional convergent-divergent nozzles designed to have simultaneous pitch and yaw thrust vectoring capability. This concept utilized divergent flap rotation of thrust vectoring in the pitch plane and deflection of flat yaw flaps hinged at the end of the sidewalls for yaw thrust vectoring. The hinge location of the yaw flaps was varied at four positions from the nozzle exit plane to the throat plane. The yaw flaps were designed to contain the flow laterally independent of power setting. In order to eliminate any physical interference between the yaw flap deflected into the exhaust stream and the divergent flaps, the downstream corners of both upper and lower divergent flaps were cut off to allow for up to 30 deg of yaw flap deflection. The impact of varying the nozzle pitch vector angle, throat area, yaw flap hinge location, yaw flap length, and yaw flap deflection angle on nozzle internal performance characteristics, was studied. High-pressure air was used to simulate jet exhaust at nozzle pressure ratios up to 7.0. Static results indicate that configurations with the yaw flap hinge located upstream of the exit plane provide relatively high levels of thrust vectoring efficiency without causing large losses in resultant thrust ratio. Therefore, these configurations represent a viable concept for providing simultaneous pitch and yaw thrust vectoring

    Case study methodologies and a wider appreciation of development planning

    Get PDF
    This article describes a case study research and training method currently being developed by the authors with the support of OECD, UNESCO and the EEC. This method is intended for personnel actively involved in urban planning and development although the method may be adapted for use in a variety of planning and management contexts. In short. the central concern is with the provision of learning systems for helping planners and those in cognate disciplines achieve a deeper understanding and thereby contribute to an improve­ment in their urban management ability. This may be particularly appropriate in countries concerned with "public accountability," and "public Involvement" in the planning and development processes

    Apparatus and method for improvised explosive device (IED) network analysis

    Get PDF
    PatentTools and apparatus are presented for identification and analysis of improvised explosive device (IED) networks, including data acquisition tools and techniques providing structured prompting and predefined answers for acquiring structured IED data reports in a streamlined fashion using uniform terminology with respect to IED components and/or structure, as well as analysis methodologies employing IED component level analysis with adjustable similarity correlation and IED attribute filtering to expeditiously identify likely IED networks using graphical renderings of IED locations in a given geolocation range of interest and connection indicators

    CASE STUDY EXPERIMENTATION AND SOME POTENTIAL GAMING SIMULATION PAYOFFS

    Get PDF
    This paper discusses the role of case.studies in relation to instructional simulation efforts to improve our environmental awareness· and capability. The 'case method' as developed by the authors is outlined and various teaching strategies are discussed. It is suggested that no single 'case' model can be advocated as ideal and more attention might properly be focused on pedagogical relationships which might ensure greater manageability and realism. Gaming-Simulation is seen as one example of how the case study method can be advanced and more widely exploited. The paper concludes with the view that simulation approaches have to be further tried and tested if environmental teaching is not to be intellectually fossilised

    Key issues in planning implementation

    Get PDF
    One of the truisms that most planners adhere to is the notion that 'planning is a continuous process'. What is also true, but often more difficult for planners to grasp, is the fact that the process itself is evolutionary and that within this dynamic of change it is not only the system which changes but the values underlying that system as well
    corecore