Vehicle emissions and roadside air quality

Individual carbon monoxide and hydrocarbon emissions were monitored from passing vehicles using the Fuel Efficiency Automobile Test at four survey sites (Bounds Green Road, Haringey (site A); Dixons Bank, Middlesborough (site B); Abbey Street, Southwark (site C); Uppingham Road, Leicester (site D)}. The remotely measured emissions data is described in terms of fleet emissions, model year emissions and model year contribution to fleet emissions. It was found that there were a large majority of low emitting vehicles contributing little to fleet emissions and a small minority of high emitting vehicles contributing significant proportions to fleet emissions. Model year analysis suggested a low association between vehicle age and mean emissions prior to 1983 but a much improved relationship after 1983. Analysis of model year contributions to fleet emissions shows new gross polluters to be the largest contributors and older vehicles playing only a minor role. The concentrations of carbon monoxide and nitrogen oxides in air were monitored, in conjunction with the FEAT measurement, at various distances from the road (roadside (on the kerb), kerbside (3 metres from the road), 7.5 metres and 15 metres from the road). A decrease of carbon monoxide and nitric oxide concentrations with distance from the road was noted for all sites with the exception of site D where meteorological parameters exerted a greater influence upon air quality than did distance from the road. The expected increase of NO2 concentration with distance from the road, as NO is oxidised to NO2, did not occur. Moreover, NO2 concentrations decreased with distance from the road. However, the production of NO2 by oxidation of NO can be inferred in two ways. Firstly, a much more gradual decline in concentrations with distance from the road was noted for NO2 compared to CO and NO, possibly due to NO2 production counteracting the reduction in concentration caused by dispersion. Secondly, an analysis of the change of ratios between nitrogen dioxide and nitric oxide with distance from the road reveals a relative increase of NO2 with distance. The air quality data were compared with the remotely measured vehicle emissions data, wind speed and wind direction. A statistical examination of the data was undertaken on a halfhourly and five minute basis (no wind data was available on a five minute basis). The halfhourly analyses for both CO and NOx produced positive correlations between vehicle emissions data and air quality, and predominantly negative correlations between wind speed and air quality. Both positive and negative correlations were observed between wind direction and CO/NOx air quality . Regression analyses were undertaken where the results were statistically significant at a 0.1 level. This reduced the sample size for CO to data collected on eight individual sampling days and to only two days for NOx• All the analysed CO sampling days recorded r2 values of greater than 0.5, such that for each sampling day at least half the variation in CO air quality is explained by the variation in on-road vehicle emissions, wind speed and wind direction. The two analysed NOx sampling days recorded r values of approximately 0.8. The five minute analyses produced were less statistically significant giving only a low degree of correlation between CO and NOx air quality and on-road vehicle emissions. Regression analyses were undertaken for only two days for CO and only one day for NOx

Learning about A level physics students’ understandings of particle physics using concept mapping

This paper describes a small-scale piece of research using concept mapping to elicit A level students' understandings of particle physics. Fifty-nine year 12 (16- and 17 year-old) students from two London schools participated. The exercise took place during school physics lessons. Students were instructed how to make a concept map and were provided with 24 topic-specific key words. Students' concept maps were analysed by identifying the knowledge propositions they represented, enumerating how many students had made each one, and by identifying errors and potential misconceptions, with reference to the specification they were studying. The only correct statement made by a majority of students in both schools was that annihilation takes place when matter and antimatter collide, although there was evidence that some students were unable to distinguish between annihilation and pair production. A high proportion of students knew of up, down and strange quarks, and that the electron is a lepton. However, some students appeared to have a misconception that everything is made of quarks. Students found it harder to classify tau particles than they did electrons and muons. Where students made incorrect links about muons and tau particles their concept maps suggested that they thought they were mesons or quarks

Metal-Substituted Microporous Aluminophosphates

This chapter aims to present the zeotypes aluminophosphates (AlPOs) as a complementary alternative to zeolites in the isomorphic incorporation of metal ions within all-inorganic microporous frameworks as well as to discuss didactically the catalytic consequences derived from the distinctive features of both frameworks. It does not intend to be a compilation of either all or the most significant publications involving metal-substituted microporous aluminophosphates. Families of AlPOs and zeolites, which include metal ion-substituted variants, are the dominant microporous materials. Both these systems are widely used as catalysts, in particular through aliovalent metal ions substitution. Here, some general description of the synthesis procedures and characterization techniques of the MeAPOs (metal-contained aluminophosphates) is given along with catalytic properties. Next, some illustrative examples of the catalytic possibilities of MeAPOs as catalysts in the transformation of the organic molecules are given. The oxidation of the hardly activated hydrocarbons has probably been the most successful use of AlPOs doped with the divalent transition metal ions Co2+, Mn2+, and Fe2+, whose incorporation in zeolites is disfavoured. The catalytic role of these MeAPOs is rationalized based on the knowledge acquired from a combination of the most advanced characterization techniques. Finally, the importance of the high specificity of the structure-directing agents employed in the preparation of MeAPOs is discussed taking N,N-methyldicyclohexylamine in the synthesis of AFI-structured materials as a driving force. It is shown how such a high specificity could be predicted and how it can open great possibilities in the control of parameters as critical in catalysis as crystal size, inter-and intracrystalline mesoporosity, acidity, redox properties, incorporation of a great variety of heteroatom ions or final environment of the metal site (surrounding it by either P or Al)

Remote sensing of carbon monoxide vehicle emissions

The University of Denver's remote sensor for automobile exhaust emissions has been used to obtain valid model year (defined here as the year of first registration) and emissions data from roadside locations in Middlesbrough and London. Mean carbon monoxide emissions have been plotted against model year to determine if there is a relationship between mean pollutant emissions and the age of the vehicle. The results initially showed a large degree of scatter and no inference, concerning age and emissions, could be made. This can be largely attributed to the older vehicles in the fleet. Older vehicles were then omitted from an additional investigation providing a much stronger relationship with R2 values of 0.88 being calculated for London and 0.77 for Middlesbrough. Analyses of model year fleet emissions were also undertaken. It was demonstrated that old vehicles do not contribute significantly to fleet emissions. Pre-1983 registered vehicles contributed only 9% of total fleet emissions in Middlesbrough and only 21% of total fleet emissions in London. It was also shown that the vast majority of fleet emissions come from a small number of highly polluting new vehicles (quintile 5). Quintile 5 for model year 1989 represented 140 vehicles (2% of the measured fleet) which contributed to 10.6% of fleet emissions at the Middlesbrough site

The application of centre manifolds to amplitude expansions. I. Ordinary differential equations

AbstractThe theory of centre manifolds for a system of ordinary differential equations is summarized and its relationship to amplitude expansions based upon multiple time scales is discussed. Emphasis is placed upon the practical computational aspects of applying centre manifold theory to near-critical problems, and, in particular, to the computation of the centre manifold. The calculations are illustrated by a detailed analysis of two problems in fluid mechanics

The application of centre manifolds to amplitude expansions. II. Infinite dimensional problems

AbstractThe theory of centre manifolds for infinite dimensional systems is described, with emphasis on the practical computational aspects of applying the theory to near-critical problems, and in particular to computation of the centre manifold. The calculations are illustrated by detailed analyses of two specific problems

The theory of pseudo-rigid bodies

This monograph concerns the development, analysis, and application of the theory of pseudo-rigid bodies. It collects together our work on that subject over the last five years. While some results have appeared else­ where, much of the work is new. Our objective in writing this mono­ graph has been to present a new theory of the deformation of bodies, one that has not only a firm theoretical basis, but also the simplicity to serve as an effective tool in practical problems. Consequently, the main body of the treatise is a multifaceted development of the theory, from foundations to explicit solutions to linearizations to methods of approximation. The fact that this variety of aspects, each examined in considerable detail, can be collected together in a single, unified treat­ ment gives this theory an elegance that we feel sets it apart from many others. While our goal has always been to give a complete treatment of the theory as it now stands, the work here is not meant to be definitive. Theories are not entities that appear suddenly one day and thereafter stand as given. Rather, they must mature and grow with time and experience. Our development is more correctly a beginning, tempting others to explore, appraise, and modify its features so as to produce something better

Fundamentals of Maxwell's kinetic theory of a simple monatomic gas treated as a branch of rational mechanics

Fundamentals of MaxwellÆs kinetic theory of a simple monatomic ga