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81.
82.
Although a considerable amount of research has been undertaken regarding the performance of T-profile noise barriers, the information available to the practicing highway engineer is confusing. For example, there is a widespread belief that the performance of a top edge, expressed as an insertion loss relative to that of the simple barrier on which it is mounted, is constant, irrespective of the relative locations of the source, barrier and receiver. In order to clarify the situation an investigation has been undertaken, using computer modelling, of the performance afforded by highway noise barriers with T-profile tops with different acoustic treatments. The relative insertion loss was found to increase systematically with increasing top width. Although the relative insertion loss afforded by a reflective T-top is small, significant attenuation can be obtained with an absorptive top. Examination of the effect on performance of the locations of source and receiver relative to that of the noise barrier indicated that, for source and receiver locations typical of those experienced for highway noise barriers, the relative insertion loss for a given width of T-top was a function of (a) the path difference between sound travelling to the receiver via the barrier top and direct sound from the source to the receiver and (b) the barrier height. Plots of relative insertion loss versus the path difference, normalised with respect to barrier heights, for a range of T-top widths and absorbent treatment, resulted in a collapse of data around well defined trend lines which offer the potential of being developed into a prediction method. 相似文献
83.
Devine CK Oldham CJ Jur JS Gong B Parsons GN 《Langmuir : the ACS journal of surfaces and colloids》2011,27(23):14497-14507
The presence of nanostructured materials in the workplace is bringing attention to the importance of safe practices for nanomaterial handling. We explored novel fiber containment methods to improve the handling of carbon nanotube (CNT) powders in the laboratory while simultaneously allowing highly uniform and controlled atomic layer deposition (ALD) coatings on the nanotubes, down to less than 4 nm on some CNT materials. Moreover, the procedure yields uniform coatings on milligram quantities of nanotubes using a conventional viscous flow reactor system, circumventing the need for specialized fluidized bed or rotary ALD reactors for laboratory-scale studies. We explored both fiber bundles and fiber baskets as possible containment methods and conclude that the baskets are more suitable for coating studies. An extended precursor and reactant dose and soak periods allowed the gases to diffuse through the fiber containment, and the ALD coating thickness scaled linearly with the number of ALD cycles. The extended dose period produced thicker coatings compared to typical doses on CNT controls not encased in the fibers, suggesting some effects due to the extended reactant dose. Film growth was compared on a range of single-walled NTs, double-walled NTs, and acid-functionalized multiwalled NTs, and we found that ultrathin coatings were most readily controlled on the multiwalled NTs. 相似文献
84.
Tingye Li AT&T Middletown NJ USA Zisen Zhao Wuhan Research Institute of Post Telecommunications Fiberhome Wuhan ChinaJianjun Yu ZTE USA Inc. wood ave. south FL Iselin NJ USA ZTE Inc. Beijing China 《中国光学快报(英文版)》2010,(9):815-815
<正>Fiber optics underpins the communications infrastructure for the information society today. Cables consisting of hair-like fibers speed data around the globe in the form of rapid pulses of light. Modern telecom 相似文献
85.
E. W. Oldham L. M. Baker M. W. Craytor W. Bolotnikov W. Gurowa I. Taranenko A. F. Hardman H. E. Barbehenn S. Minatoya I. Aoe I. Nagai B. Krepss Eugene Cheraskowa L. Weisbruth I. Mogoritschewa E. J. Stuber M. I. Archangelskaja S. Ginsburg A. Dereganskaja W. Kreps w. G. Schaposchnikow N. A. Kalinitschewa N. A. Liwschitz W. F. Polikarpowa I. E. Filinow W. P. Schatalow T. Ebe F. Isrjumow J. Kusina A. Ssimakowa 《Analytical and bioanalytical chemistry》1937,109(1-2):71-76
86.
W. J. Oldham Jr. B. S. Matteson J. L. Miller C. T. Lake M. Attrep Jr. 《Journal of Radioanalytical and Nuclear Chemistry》2013,296(2):889-892
Discarded rusty iron objects in the environment adsorb trace plutonium mobilized by oxygenated surface waters (e.g. rain, snow melt). Radiochemical and mass spectrometric analysis of the surface oxide coating of modest collections of rusty nails retrieved from remote locations provides a global fallout plutonium signal of up to 2 × 1010 atoms of 239Pu per sample. The median 239Pu measurement for 10 samples from five locations was 2.82 × 109 atoms. The average 240Pu/239Pu atom ratio was 0.176 ± 0.012, consistent with the value accepted for global fallout. 相似文献
87.
The N‐heterocyclic carbene, 1,3‐dimesityl‐imidazol‐2‐ylidene (IMes) reacts with tetrahydrofuran (THF) in the presence of an oxidizing uranyl triflate complex, UO2(OTf)2(thf)3 (?OTf = ?OSO2CF3), to give 1,4‐bis(1,3‐dimesityl‐2‐imidazolium)‐1,3‐butadiene bis(trifluoromethanesulfonate), formally understood as the coupling product of two equivalents of IMes with [CH?CH? CH?CH](OTf)2. Copyright © 2005 John Wiley & Sons, Ltd. 相似文献
88.
89.
We calculate the αs2 to three-jet cross sections in e+e? annihilation in a scheme that uses regulator masses for the infrared and collinear divergences. Using various methods to define the three-jet region, we find that the corrections to the O(αs) cross sections are large. 相似文献
90.
The action of courtyard houses in reducing the noise nuisance from road traffic is examined using the techniques of computer simulation and acoustic scale modelling. This building form is found to be capable of reducing the noise level experienced within a protected space (indoor or outdoor) by a significant amount. For a courtyard house a fixed distance from a roadway the most significant parameter is found to be the height of the courtyard walls. The effect of varying courtyard width and depth on the net attenuation is slight by comparison with the effect observed on varying the height of the walls. 相似文献