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  • 1
    Electronic Resource
    Electronic Resource
    Experimental studies on the sensitivity of fire detectors (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Fire and Materials 18 (1994), S. 221-230 
    Details
    ISSN: 0308-0501
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Architecture, Civil Engineering, Surveying , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Experimental studies were performed to assess the sensitivity and response times of four types of fire detectors: ionization smoke, optical smoke, infra-red and rate of heat rise detectors. The detectors were installed in a fire chamber and subjected to ten types of fire under a controlled environment. Based on the experimental results, correlations between the fire properties and the response times of the detectors were found. Data collected on the predicted fire detector response time were analyzed by a statistical method. Those empirical expressions would be important for practising engineers in designing fire-detection systems and setting responses for detectors in buildings of different uses.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/fam.810180405
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    Paper (German National Licenses)
    Fulltext
  • 2
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    Modifications to WRF's dynamical core to improve the treatment of moisture for large-eddy simulations (2015)
    Wiley
    Details
    Publication Date: 2015-10-14
    Description: Yamaguchi and Feingold (2012) note that the cloud fields in their large-eddy simulations (LESs) of marine stratocumulus using the Weather Research and Forecasting (WRF) model exhibit a strong sensitivity to time stepping choices. In this study, we reproduce and analyze this sensitivity issue using two stratocumulus cases, one marine and one continental. Results show that (1) the sensitivity is associated with spurious motions near the moisture jump between the boundary layer and the free atmosphere, and (2) these spurious motions appear to arise from neglecting small variations in water vapor mixing ratio ( q v ) in the pressure gradient calculation in the acoustic sub­stepping portion of the integration procedure. We show that this issue is remedied in the WRF dynamical core by replacing the prognostic equation for the potential temperature θ with one for the moist potential temperature θ m =θ (1 + 1.61 q v ), which allows consistent treatment of moisture in the calculation of pressure during the acoustic sub­steps. With this modification, the spurious motions and the sensitivity to the time stepping settings (i.e., the dynamic time step length and number of acoustic sub­steps) are eliminated in both of the example stratocumulus cases. This modification improves the applicability of WRF for LES applications, and possibly other models using similar dynamical core formulations, and also permits the use of longer time steps than in the original code. This article is protected by copyright. All rights reserved.
    Electronic ISSN: 1942-2466
    Topics: Geography , Geosciences
    Published by Wiley on behalf of American Geophysical Union (AGU).
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    PAPER CURRENT
  • 3
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    NASA ACTS Multibeam Antenna (MBA) System (1986)
    In:  Other Sources
    Details
    Publication Date: 2011-11-24
    Description: The design of the Advanced Communications Technology Satellite MBA system, which provides both spot beam and scanning beam coverage to both high and low burst rates data-users is examined. The MBA consists of receive and transmit antennas installed on a common precision mounting platform that is integrated to the bus through three flexures; a lightweight system with low thermal distortion is obtained by using composite materials for the MBA structures. The RF design, which is a Cassegrain reflector with a large equivalent focal length/aperture size, is described. Consideration is given to the position of the feed in order to minimize scan loss and sidelobe levels, the size of the subreflector in order to minimize feed spillover, and antenna performance degradation caused by reflector surface distortion. Breadbroad model test result reveal that the maximum sidelobe level outside the 2.5 HPBW region is -30 dB or lower relative to the power.
    Keywords: SPACECRAFT INSTRUMENTATION
    Format: text
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    NASA TECHNICAL REPORTS
  • 4
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    De-Sexualizing Partner Notification: A Qualitative Study on Chinese Young Adults with Chlamydia (2021)
    Molecular Diversity Preservation International
    Details
    Publication Date: 2021-04-12
    Description: Background: Chlamydia is common amongst the sexually active population in Hong Kong. As most cases are asymptomatic, partner notification may be helpful in controlling chlamydia. This study examined attitudes towards partner notification for chlamydia among Hong Kong Chinese youths in order to inform a culturally appropriate, patient-empowering sexual health service. Methods: Sixteen individuals (aged 20 to 31) who received a confirmed diagnosis of chlamydia within the previous twelve months of data collection were recruited from two community-based organizations between June and December 2017. Semi-structured individual interviews were conducted by a health psychologist. Results: Nine participants notified a total of eleven current and ex-partners. Seven participants did not notify their sexual partner(s). Our findings revealed how participants struggled with the discrediting sexual aspect of their infection, and how de-sexualizing the infection and selected disclosure facilitated partner notification and social acceptance. Perceived stigma regarding chlamydia however did not dissipate with their disclosure. Participants did not perceive lasting impact of chlamydia on their well-being as they thought they have much control over whether and how to disclose to their (future) partners. All participants agreed there was a pressing need to raise public awareness on this silent but highly prevalent sexually transmitted infection. Conclusions: Our findings illustrate the complex struggle behind communicating about chlamydia to one’s sexual partner and how strategizing the disclosure process served to circumvent embarrassment and foster testing of sexual partners.
    Print ISSN: 1661-7827
    Electronic ISSN: 1660-4601
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Medicine
    Published by Molecular Diversity Preservation International
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    PAPER CURRENT
  • 5
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    Antennas for 20/30 GHz and beyond (1989)
    In:  CASI
    Details
    Publication Date: 2013-08-31
    Description: Antennas of 20/30 GHz and higher frequency, due to the small wavelength, offer capabilities for many space applications. With the government-sponsored space programs (such as ACTS) in recent years, the industry has gone through the learning curve of designing and developing high-performance, multi-function antennas in this frequency range. Design and analysis tools (such as the computer modelling used in feedhorn design and reflector surface and thermal distortion analysis) are available. The components/devices (such as BFN's, weight modules, feedhorns and etc.) are space-qualified. The manufacturing procedures (such as reflector surface control) are refined to meet the stringent tolerance accompanying high frequencies. The integration and testing facilities (such as Near-Field range) also advance to facilitate precision assembling and performance verification. These capabilities, essential to the successful design and development of high-frequency spaceborne antennas, shall find more space applications (such as ESGP) than just communications.
    Keywords: COMMUNICATIONS AND RADAR
    Type: NASA, Langley Research Center, Earth Science Geostationary Platform Technology; p 313-327
    Format: application/pdf
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    NASA TECHNICAL REPORTS
  • 6
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    Multibeam Antenna Design and Development for NASA Advanced Communications Technology Satellite (ACTS) (1986)
    In:  Other Sources
    Details
    Publication Date: 2019-07-13
    Description: The design of the ACTS multibeam antenna is described, and its performance is evaluated. The multibeam antenna is designed to cover the continential U.S. and provides three fixed spot beams for high burst rate operations and two scanning beams for low burst rate operations. The antenna has one main reflector, a dual polarized subreflector, and two orthogonal feed assemblies. The feed system is to receive a linearly polarized communication signal from 28.9-30.0 GHz and to provide the elevation and azimuth error tracking signals at 29.975 GHz with a 0.01 deg tracking accuracy. The feed system uses a single multiflare conical horn and a multimode coupler to provide a symmetric primary pattern for the communication signal. The sidelobe characteristics of the reflector, and the relation between the sidelobe level and surface distortion are studied. It is noted that the performance measurements for the multibeam antenna correlate well with predictions for secondary patterns and scan characteristics.
    Keywords: SPACECRAFT DESIGN, TESTING AND PERFORMANCE
    Type: Global Telecommunications Conference - GLOBECOM 1986; Dec 01, 1986 - Dec 04, 1986; Houston, TX; United States
    Format: text
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    NASA TECHNICAL REPORTS
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