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排序方式: 共有826条查询结果,搜索用时 15 毫秒
91.
An accidental or intentional release of hazardous chemical, biological, radiological, or nuclear material into the atmosphere obligates responsible agencies to model its transport and dispersion in order to mitigate the effects. This modeling requires input parameters that may not be known and must therefore be estimated from sensor measurements of the resulting concentration field. The genetic algorithm (GA) method used here has been successful at back-calculating not only these source characteristics but also the meteorological parameters necessary to predict the contaminants subsequent transport and dispersion. This study assesses the impact of sensor thresholds, i.e. the sensor minimum detection limit and saturation level, on the ability of the algorithm to back-calculate modeling variables. The sensitivity of the back-calculation to these sensor constraints is analyzed in the context of an identical twin approach, where the data is simulated using the same Gaussian Puff model that is used in the back-calculation algorithm in order to analyze sensitivity in a controlled environment. The solution is optimized by the GA and further tuned with the Nelder-Mead downhill simplex algorithm. For this back-calculation to be successful, it is important that the sensor capture the maximum concentrations. 相似文献
92.
93.
The difficulties of operationalizing race in research and practice for social, behavioral, and genetic researchers and practitioners are neither new nor related to recent genetic knowledge. For geneticists, the bases for understanding groups are clines, observed traits that gradually change in frequency between geographic regions without distinct identifiable population boundaries and population histories that carry information about the distribution of genetic variants. For psychologists, race may not exist or be a social and cultural construct associated with fluid social inferences. Because definitions of populations and race can be socially and biologically incongruent, the authors suggest that geneticists and social and behavioral scientists and clinicians attend to external validity issues by operationalizing population and racial categories and avoiding race proxies for other biological, social, and cultural constructs in research designs, data analyses, and clinical practice. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
94.
Decomposition and decoupling effects of carbon dioxide emission from highway transportation in Taiwan,Germany, Japan and South Korea 总被引:1,自引:0,他引:1
We adopted the Divisia index approach to explore the impacts of five factors on the total carbon dioxide emissions from highway vehicles in Germany, Japan, South Korea and Taiwan during 1990–2002. CO2 emission was decomposed into emission coefficient, vehicle fuel intensity, vehicle ownership, population intensity and economic growth. In addition, the decoupling effects among economic growth, transport energy demand and CO2 emission were analyzed to better understand the fuel performance and CO2 mitigation strategies for each country. From our results, we suggest that the rapid growths of economy and vehicle ownership were the most important factors for the increased CO2 emissions, whereas population intensity contributed significantly to emission decrease. Energy conservation performance and CO2 mitigation in each country are strongly correlated with environmental pressure and economic driving force, except for Germany in 1993 and Taiwan during 1992–1996. To decouple the economic growth and environmental pressure, proponents of sustainable transport policy in Taiwan should focus on improving the operation and energy use of its highway transportation system by implementing an intelligent transportation system (ITS) with demand management, constructing an integrated feeder system, and encouraging the use of green transport modes. 相似文献
95.
Sue Kidd Brian Goodey Charles W. J. Withers Beverly A. Sandback Allan Reeve 《Landscape Research》1995,20(1):45-48
BT Environment City Bulletin: The Big Picture - all eight topics under one roof Edited by C. Wood, 1994, Lincoln, The Wildlife Trusts, 110pp., £19.00 for local authorities, £14.00 for local businesses, £9.00 for voluntary groups.
Theme Parks, Leisure Centres, Zoos and Aquaria Anthony and Patricia Wylson, 1994, Harlow, Longman, 183pp. ISBN 0 582 09928 5, hb £60.00
The Picturesque Landscape: Visions of Georgian Herefordshire Edited by Stephen Daniels and Charles Watkins, 1994, Department of Geography, University of Nottingham, 100pp. ISBN 0 85358 033 2, £7.50
The Countryside Ideal: Anglo-American Images of Landscape Michael Bunce, 1994, London, Routledge, 232pp. ISBN 0 415 10435 1
Ordering Space: Types in Architecture and Design Karen A Frank and Lynda H Schneekloth (eds.), 1994, New York, Van Norstrand Reinhold, 383pp ISBN 0 442 01233 0, pb £34.50 相似文献
Theme Parks, Leisure Centres, Zoos and Aquaria Anthony and Patricia Wylson, 1994, Harlow, Longman, 183pp. ISBN 0 582 09928 5, hb £60.00
The Picturesque Landscape: Visions of Georgian Herefordshire Edited by Stephen Daniels and Charles Watkins, 1994, Department of Geography, University of Nottingham, 100pp. ISBN 0 85358 033 2, £7.50
The Countryside Ideal: Anglo-American Images of Landscape Michael Bunce, 1994, London, Routledge, 232pp. ISBN 0 415 10435 1
Ordering Space: Types in Architecture and Design Karen A Frank and Lynda H Schneekloth (eds.), 1994, New York, Van Norstrand Reinhold, 383pp ISBN 0 442 01233 0, pb £34.50 相似文献
96.
软件无线电是一种新兴技术,通过软件使多种业务、多种标准、多个频段与灵活的无线电系统的组合成为可重新配置和可重新编程的。介绍了软件无线电的概念及系统结构,并进一步讨论了现阶段软件无线电所面临的技术问题以及相应的实现方案。 相似文献
97.
Kevin Coe David Domke Erica S. Graham Sue Lockett John Victor W. Pickard 《The Journal of communication》2004,54(2):234-252
Binary communications represent the world as a place of polar opposites. Such conceptions of reality, although not uncommon in Western thought, take on a heightened importance when political leaders employ them in a concerted, strategic discourse in a mass media environment. With this in mind, this research offers a conception of binary discourse and uses this as a foundation to examine (a) the use of binaries by U.S. President George W. Bush in 15 national addresses, from his inauguration in January 2001 to commencement of the Iraq War in March 2003, and (b) the responses of editorials in 20 leading U.S. newspapers to the president's communications. 相似文献
98.
Yiqun Bai Punit Chiniwalla Edmund Elce Robert A. Shick James Sperk Sue Ann Bidstrup Allen Paul A. Kohl 《应用聚合物科学杂志》2004,91(5):3023-3030
In the microelectronics industry, the drive for increasing device speed, level of functionality and shrinking size has placed significant demands on the performance characteristics of polymer dielectrics. In this study, a negative acting, photodefinable dielectric formulation based on a copolymer of decylnorborne (decylNB) and epoxynorbornene (AGENB) was investigated for use in electronics packaging. The structure–property relations of this copolymer were investigated. Copolymer composition and processing conditions were shown to significantly affect the properties of the final polymer films. A lower content of AGENB results in lower moisture absorption, dielectric constant, modulus and residual stress, but it compromises multilayer capability. High crosslink density lowers the dielectric constant but increases the modulus and residual stress. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 91: 3023–3030, 2004 相似文献
99.
Six batches of hard gelatin capsules were manufactured to explore the effect of disintegrant level and capsule fill porosity on the dissolution behavior of encapsulated dosage forms after exposure to high humidity. Size 0 capsules filled with powder blends containing 10 and 25% disintegrant dissolved faster than size 2 capsules filled with identical powder blends after storage under direct high humidity exposure. Interestingly, the trend was reversed when these identical products were exposed to high humidity but stored in, and protected by, a high density bottle-polypropylene container/closure system. It is hypothesized that capsules filled with a highly compacted powder blend, which are directly exposed to high humidity form a water layer at the gelatin-powder blend interface that inactivates the disintegrant. 相似文献
100.