Inverse modelling of NO_<i>x</i> emissions over eastern China: uncertainties due to chemical non-linearity

Satellite observations of nitrogen dioxide (NO2) have often been used to derive nitrogen oxides (NOx = NO + NO2) emissions. A widely used inversion method was developed by Martin et al. (2003). Refinements of this method were subsequently developed. In the context of this inversion method, we show that the local derivative (of a first-order Taylor expansion) is more appropriate than the “bulk ratio” (ratio of emission to column) used in the original formulation for polluted regions. Using the bulk ratio can lead to biases in regions of high NOx emissions such as eastern China due to chemical non-linearity. Inverse modelling using the local derivative method is applied to both GOME-2 and OMI satellite measurements to estimate anthropogenic NOx emissions over eastern China. Compared with the traditional method using bulk ratio, the local derivative method produces more consistent NOx emission estimates between the inversion results using GOME-2 and OMI measurements. The results also show significant changes in the spatial distribution of NOx emissions, especially over high emission regions of eastern China. We further discuss a potential pitfall of using the difference of two satellite measurements to derive NOx emissions. Our analysis suggests that chemical non-linearity needs to be accounted for and that a careful bias analysis is required in order to use the satellite differential method in inverse modelling of NOx emissions.

Inverse modeling of NOx</sub> emissions over eastern China: Uncertainties due to chemical nonlinearity

Satellite observations of nitrogen dioxide (NO2) have often been used to derive nitrogen oxides (NOx = NO + NO2) emissions. A widely used inversion method was developed by Martin et al. (2003). Refinements of this method were subsequently developed. In the context of this inversion method, we show that the local derivative (of a first-order Taylor expansion) is more appropriate than the “bulk ratio” (ratio of emission to column) used in the original formulation for polluted regions. Using the bulk ratio can lead to biases in regions of high NOx emissions such as eastern China due to chemical nonlinearity. Inverse modeling using the local derivative method is applied to both GOME-2 and OMI satellite measurements to estimate anthropogenic NOx emissions over eastern China. Compared with the traditional method using bulk ratio, the local derivative method produces more consistent NOx emission estimates between the inversion results using GOME-2 and OMI measurements. The results also show significant changes in the spatial distribution of NOx emissions especially over high emission regions of eastern China. We further discuss a potential pitfall of using the difference of two satellite measurements to derive NOx emissions. Our analysis suggests that chemical nonlinearity needs to be accounted for and that a careful bias analysis is required in order to use the satellite differential method in inverse modeling of NOx emissions.

Explosive Compaction of Metal Powder

In the present study ,the shock wave consolidation technique was used to produce bulk samples from metal powders .To method of consolidation were used to produce bulk samples, single consolidation and Two-Coaxial consolidation .after explosion ,the container tubes were cut and density of bulk , ratio of RDX to mass of flying tube (R) ,ratio of RDX to mass of powder(K),detonation velocity ,detonation pressure ,kinetic energy of flyer tubes and plastic work were calculated for all tests and finally cross section of samples were observed by SEM. The results show modified situation for Two-Coaxial consolidation by comparison in single tube consolidation.

Copper Phthalocyanine Quasi-1D Nanostructures: Growth Morphologies and Gas Sensing Properties

The growth conditions of meso- and nanoscopic copper phthalocyanine quasi-1D structures, single crystalline whiskers and "nanowebs" were investigated on various technologically important substrates and were compared to existing literature. The synthesized morphologies were used to fabricate organic conductometric gas-sensing devices, and their sensitivity and selectivity toward NOx were investigated. The obtained results demonstrate excellent sensitivity and selectivity of these quasi-1D chemiresistors. Both the response time of the quasi-1D CuPc sensors and their overall gas sensing performance can be further enhanced by reducing the surface-to-bulk ratio of these nano- and meso-structures.