<?xml version="1.0" encoding="utf-8"?><rss version="2.0" xmlns:atom="http://www.w3.org/2005/Atom"><channel><title>TRB Publications Index</title><link>http://pubsindex.trb.org/</link><atom:link href="http://pubsindex.trb.org/common/TRIS Suite/feeds/rss.aspx?tc=NN%3ADsmrjc%2A" rel="self" type="application/rss+xml" /><description></description><language>en-us</language><copyright>Copyright © 2015. National Academy of Sciences. All rights reserved.</copyright><docs>http://blogs.law.harvard.edu/tech/rss</docs><managingEditor>tris-trb@nas.edu (Bill McLeod)</managingEditor><webMaster>tris-trb@nas.edu (Bill McLeod)</webMaster><image><title>TRB Publications Index</title><url>http://pubsindex.trb.org/Images/PageHeader-wTitle.png</url><link>http://pubsindex.trb.org/</link></image><item><title>ACCURACY OF PREDICTION OF URBAN AIR POLLUTANT CONCENTRATIONS BY DIFFUSION MODELS</title><link>http://pubsindex.trb.org/view/46911</link><description><![CDATA[Projections of future transportation-related air quality impacts require the use of mathematical models that relate emissions to air quality.  Whereas the derivation and use of such models have received much attention (at least for inert pollutants, such as CO), much less attention has been paid to questions of the interpretation of th concentrations these models predict and how the predictions relate to real atmospheric quantities.  Concepts of validity and accuracy must be carefully defined for any model that is to be used in order that the predictions from the model can be properly evaluated.  The purpose of this paper is to formulate the concepts of validity and accuracy for atmospheric air pollutant diffusion models and to suggest numerical experiments that can be used to test both the validity and the accuracy of the models.  /Author/]]></description><pubDate>Mon, 21 Sep 1981 00:00:00 GMT</pubDate><guid>http://pubsindex.trb.org/view/46911</guid></item><item><title>NUMERICAL SIMULATION OF ATMOSPHERIC ICE ACCRETION</title><link>http://pubsindex.trb.org/view/86394</link><description><![CDATA[Time-dependence enters into calculations of ice accretion on objects primarily through terms dependent on the initial conditions and size and geometry of the object.  A numerical technique to include the time-dependence is described here as well as simulation of complex situations where the conditions vary, for example, along a helicopter rotor blade.  Some results of varying droplet sizes, velocity, and droplet distributions are presented.  These indicate the general dependence of ice accretion on these parameters as well as illustrate the utility of numerical techniques in seeing how these effects can influence the rates of ice accretion for particular initial conditions.  /Authors/]]></description><pubDate>Wed, 13 Jun 1979 00:00:00 GMT</pubDate><guid>http://pubsindex.trb.org/view/86394</guid></item><item><title>ATMOSPHERIC AND WIND TUNNEL STUDIES OF AIR POLLUTION DISPERSION NEAR HIGHWAYS</title><link>http://pubsindex.trb.org/view/86110</link><description><![CDATA[Atmospheric and wind tunnel studies of gaseous dispersion near roadways have identified new concepts regarding the influence of roadway traffic and stimulated the development of a versatile yet simple simulation model, ROADMAP. Influences of site geometry and roadway configurations were observed and quantified.  Two effects found to be particulary significant to microscale dispersion were (a) thermal turbulence and buoyancy caused by vehicular waste heat and (b) mechanical turbulence from highway traffic. ROADMAP simulates two-dimensional gaseous dispersion patterns for various roadway configurations including grade-level, vertical, and slant-wall cut, fill, and viaduct sections.  Development of the model is first detailed for a uniform, grade-level freeway.  Dispersion patterns were obtained up to heights of 14 m and to downwind distances of 100 m by a sampling array that measured meteorological conditions and concentrations of carbon monoxide and two artificial tracer gases relaeased in the traffic. Comparison of equivalent field and wind-tunnel tests for grade-level roads shows good agreement except for acute wind-roadway angles.  ROADMAP's capability for varied site geometries was evaluated by analyzing field and wind tunnel tests for 20 roadway configurations.  Comparisions of ROADMAP to independent cabon monoxide data (i.e., data not used in developing the model) from the grade-level field tests resulted in high values of the linear correlation coefficient: 0.91 for neutral stability, 0.67 for stable atmospheric conditions, and 0.80 for unstable conditions. Values for the cut and elevated-section tests in the wind tunnel ranged from 0.69 to 0.93.  /Author/]]></description><pubDate>Sat, 26 May 1979 00:00:00 GMT</pubDate><guid>http://pubsindex.trb.org/view/86110</guid></item></channel></rss>