26,080 research outputs found

    The mechanical behavior of cross-rolled beryllium sheet

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    In response to the failure of a conical section of the Insat C satellite during certification testing, the use of beryllium for payload structures, particularly in sheet product form, is being reevaluated. A test program was initiated to study the tensile, shear, and out-of-plane failure modes of beryllium cross-rolled sheet and to apply data to the development of an appropriate failure criterion. Tensile test results indicated that sanding the surface of beryllium sheet has no significant effect on yield strength but can produce a profound reduction in ultimate strength and results obtained by finite element analysis. Critical examination of these test results may contribute to the modification of a JSC policy for the use of beryllium in orbiter and payload structures

    Study to determine potential flight applications and human factors design guidelines for voice recognition and synthesis systems

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    A study was conducted to determine potential commercial aircraft flight deck applications and implementation guidelines for voice recognition and synthesis. At first, a survey of voice recognition and synthesis technology was undertaken to develop a working knowledge base. Then, numerous potential aircraft and simulator flight deck voice applications were identified and each proposed application was rated on a number of criteria in order to achieve an overall payoff rating. The potential voice recognition applications fell into five general categories: programming, interrogation, data entry, switch and mode selection, and continuous/time-critical action control. The ratings of the first three categories showed the most promise of being beneficial to flight deck operations. Possible applications of voice synthesis systems were categorized as automatic or pilot selectable and many were rated as being potentially beneficial. In addition, voice system implementation guidelines and pertinent performance criteria are proposed. Finally, the findings of this study are compared with those made in a recent NASA study of a 1995 transport concept

    Executable assertions and flight software

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    Executable assertions are used to test flight control software. The techniques used for testing flight software; however, are different from the techniques used to test other kinds of software. This is because of the redundant nature of flight software. An experimental setup for testing flight software using executable assertions is described. Techniques for writing and using executable assertions to test flight software are presented. The error detection capability of assertions is studied and many examples of assertions are given. The issues of placement and complexity of assertions and the language features to support efficient use of assertions are discussed

    TSUNAMI INFORMATION SOURCES PART 2

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    Tsunami Information Sources (Robert L. Wiegel, University of California, Berkeley, CA, UCB/HEL 2005-1, 14 December 2005, 115 pages), is available in printed format, and on a diskette. It is also available in electronic format at the Water Resources Center Archives, University of California, Berkeley, CA http:www.lib.berkeley.edu/WRCA/tsunamis.htmland in the International Journal of The Tsunami Society, Science of Tsunami Hazards (Vol. 24, No. 2, 2006, pp 58-171) at http://www.sthjournal.org/sth6.htm.This is Part 2 of the report. It has two components. They are: 1.(Sections A and B). Sources added since the first report, and corrections to a few listed in the first report. 2.(Sections C and D). References from both the first report and this report, listed in two categories:Section C. Planning and engineering design for tsunami mitigation/protection; adjustments to the hazard; damage to structures and infrastructureSection D. Tsunami propagation nearshore; induced oscillations; runup/inundation (flooding) and drawdown

    Shared-Use Bus Priority Lanes On City Streets: Case Studies in Design and Management, MTI Report 11-10

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    This report examines the policies and strategies governing the design and, especially, operations of bus lanes in major congested urban centers. It focuses on bus lanes that operate in mixed traffic conditions; the study does not examine practices concerning bus priority lanes on urban highways or freeways. Four key questions addressed in the paper are: How do the many public agencies within any city region that share authority over different aspects of the bus lanes coordinate their work in designing, operating, and enforcing the lanes? What is the physical design of the lanes? What is the scope of the priority use granted to buses? When is bus priority in effect, and what other users may share the lanes during these times? How are the lanes enforced? To answer these questions, the study developed detailed cases on the bus lane development and management strategies in seven cities that currently have shared-use bus priority lanes: Los Angeles, London, New York City, Paris, San Francisco, Seoul, and Sydney. Through the case studies, the paper examines the range of practices in use, thus providing planners and decision makers with an awareness of the wide variety of design and operational options available to them. In addition, the report highlights innovative practices that contribute to bus lanes’ success, where the research findings make this possible, such as mechanisms for integrating or jointly managing bus lane planning and operations across agencies

    Dynamic Soil Properties, Seismic Downhole Arrays and Applications in Practice

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    Downhole arrays are deployed worldwide to record seismic ground response in near-surface strata. The information supplied by these arrays is increasingly becoming the basis for verification, and for development and calibration of predictive tools and design procedures. Advances __ in sensors and information technologies will further expedite this learning process, opening the door for worldwide sharing and collaboration. In this paper, the following topics are addressed: i) A summary of downhole array installations and data in the U.S. and in the Taiwan, Hualien and Lotung sites, ii) An overview of related current research efforts worldwide, iii) Downhole array system identification analyses for lateral and vertical site amplification, iv) Downhole array analyses related to liquefaction and availability of Internet websites for conducting online computations (http:/cvclic.ucsd.edu), and v) Summary of findings, and needs towards future advancements
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