Emissions discrepancies

NO emissions did not exceed 2 ng Nm s and their measurement was only possible by chamber methods. The low NO emissions but high NjO emissions show that denitrification was the main source of NjO at this site. The discrepancies between the chamber and micrometeorological methods illustrated the need to define the flux-footprint of a micrometeorological measurement very carefully, and to use this information in the field to choose the locations in which chambers are placed. Without such an approach, the integration of results from chambers into estimates of field-scale emission remains an uncertain method. 

The best precision attainable with present apparatus for reasonable counting intervals should correspond to a standard deviation near 0.02% for a major constituent in an ideal sample properly handled. In most x-ray emission spectrography, the standard deviation is 1% or greater. Much of this discrepancy must be traceable to the way in which samples are prepared, and handled in the spectrograph, manipulation of the... 

In Fig. 1, a comparison can be observed for the prediction by the honeycomb reactor model developed with the parameters directly obtained from the kinetic study over the packed-bed flow reactor [6] and from the extruded honeycomb reactor for the 10 and 100 CPSI honeycomb reactors. The model with both parameters well describes the performance of both reactors although the parameters estimated from the honeycomb reactor more closely predict the experiment data than the parameters estimated from the kinetic study over the packed-bed reactor. The model with the parameters from the packed-bed reactor predicts slightly higher conversion of NO and lower emission of NHj as the reaction temperature decreases. The discrepancy also varies with respect to the reactor space velocity. 

It has been suggested that the photochemical reaction of pentachlorophenol in aqueous solution to produce octachlorodibenzo[l,4] dioxin and some of the heptachloro congener could account for the discrepancy between values for the emission of chlorinated dioxins and their deposition, which is significant for the octachloro congener (Baker and Hites 2000). 

The broad band centered at about 6 eV and following this peak in the UO2 spectrum, and appearing also in the Th02 spectrum, is much the same in the two oxides hence, the attribution to emission from an essentially 2p occupied band, which, in an ionic picture, is the ligand valence band of the two oxides. There is some discrepancy between the results of different investigations about the detailed shape of this band. In Table 3 we have hsted the main features of the valence band spectrum. 

In the photoelectric method, the measured average work function is always less than the true since patches of high work function tend to be excluded from the emission process. Thus, the nonuniform distribution of adsorbate on a patch surface may cause a slight discrepancy in the evaluation of A. Experimentally, the photoelectric method has various limitations. Photocurrents of the order of 10 A. must be measured accurately in the region of vo, and for films of work function greater than 5 v., the threshold frequency lies in the far ultraviolet—a practical disadvantage. Furthermore, the method is inapplicable at pressures in excess of 10 mm. Hg because of ionization of the gas by collision. 

It is important to note that values are of the same order of magnitude whether conventional UV or laser radiation were used (Table I). This result is in contrast with the recent work of Sadhir et al. (7) on the photopolymerization of maleic anhydride and styrene, induced by the 363.8 nm emission of an argon ion laser. That work showed to be the laser initiation 1000 times more energy efficient than the UV-induced polymerization. This discrepancy may arise from two factors (i) the lower light-intensity used in the laser irradiation that should favor chain propagation and (ii) differences in the way of comparing the... 

Table VI shows the major element composition of the samples as determined by the various laboratories. This table was compiled to emphasize that while there are large discrepancies in the results, most of the laboratories could characterize the samples correctly. Thus, sample 1 is a moderately high tin bronze (Sn ca. 15% ) with about 1% lead and little iron or zinc. Laboratories that fail on the tin value in this characterization are 01 (old), and 04 (old), possibly 05 with a tin value of 20% (although this is an optical emission spectrographic value and falls in the right range), 24 (which doesn t claim any accuracy for its tin result), and 34. Laboratory 01 (old) also has a low lead value as do 08 and 24. Thus, six of 23 laboratories (or about 25% of the results) fail to characterize the samples correctly while the other 17 characterize this sample as a moderately high tin bronze with a little lead.

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