نتایج جستجو برای: nitrogen oxides
تعداد نتایج: 136750 فیلتر نتایج به سال:
Metropolitan scale studies of transport-based air pollution have emphasized inputs from the passenger vehicle fleet, with minimal attention given to the role of urban goods movement. Furthermore, little is known about the spatial distribution of transport related emissions. This study uses an integrated urban land use and transport model (IMULATE) for Hamilton, Canada, to examine the contributi...
In the present work the degradation of nitrogen oxides (NOx) by concrete paving stones containing TiO2 to be applied in road construction is studied. A kinetic model is proposed to describe the photocatalytic reaction of nitric oxide (NO) in a standard flow laminar photoreactor irradiated with UV lamps. In addition the influence of several parameters that can affect the performance of these sto...
Nighttime Chemistry and Morning Isoprene Can Drive Urban Ozone Downwind of a Major Deciduous Forest.
Isoprene is the predominant non-methane volatile organic compound emitted to the atmosphere and shapes tropospheric composition and biogeochemistry through its effects on ozone, other oxidants, aerosols, and the nitrogen cycle. Isoprene is emitted naturally by vegetation during daytime, when its photo-oxidation is rapid, and in the presence of nitrogen oxides (NOx) produces ozone and degrades a...
The problem of photochemical oxidant pollution, 98% of which is ozone, is addressed. Ozone itself is not the cause of all adverse effects (e.g., peroxyacetyl nitrites cause eye irritation). The typical sequence in the development of oxidant pollution is an initial increase in nitrous oxide, followed by nitrogen dioxide, followed by ozone. These pollutants can be carried long distances and may h...
In this paper, the N2O plasma oxides in-situ grown on CF4 plasma pretreated silicon substrate is proposed and demonstrated having excellent characteristics. Those are precise thickness control, low temperature fabrication, low leakage current, and high reliability. Those good features will enhance the scaling down ability of CMOS devices. The mechanisms that make the process success are also di...
The integrated mechanism of the catalytic oxidation of NO by N2O on the metal-free support of nitrogen doped graphene (NG) is investigated using density function theory calculations. The results indicate that the N2O can be intensively adsorbed on NG support, while the NO, N2, NO2 are all weakly adsorbed. In the oxidation process, a two-step mechanism is identified: the dissociation of N2O foll...
[1] Spatially resolved weekly NO2 variations are obtained from 2003 to 2005 Scanning Imaging Absorption Spectrometer for Atmospheric Cartography (SCIAMACHY) tropospheric NO2 columns for three different types of regions: urban, rural, and rural-point (rural with significant electricity generation unit (EGU) emissions). Regions are compared for magnitudes and weekly profiles. Rural regions do not...
We present an analysis of the NOy (NOx + other oxidized species) measurements at the high alpine site Jungfraujoch (JFJ, 3580 m a.s.l.) for the period 1998–2009, which is the longest continous NOy data set reported from the lower free troposphere worldwide. Due to stringent emission control regulations, nitrogen oxides (NOx) emissions have been reduced significantly in Europe since the late 198...
In order to lower the Nitrogen Oxides (NOx) concentration in internal combustion engine emissions and to improve performance, Exhaust Gas Recirculation (EGR) and Scavenging mechanism are introduced. EGR recirculates a fraction of the exhaust gas back into the cylinders, thus diluting the intake air. This lowers the maximum combustion temperature and, since the formation of NOx is heavily depend...
In this study, the effects of injection pressure and timing on the performance and emission characteristics of a DI diesel engine using methanol (5%, 10% and 15%) blended-diesel fuel were investigated. The tests were conducted on three different injection pressures (180, 200 and 220 bar) and timings (15 , 20 , and 25 CA BTDC) at 20 Nm engine load and 2200 rpm. The results indicated that brake s...
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