Vehicle-specific power (VSP) has been found to be highly correlated with vehicle emissions. It is used in many studies on emission modeling such as the MOVES (Motor Vehicle Emissions Simulator) model. The existing studies develop specific VSP distributions (or OpMode distribution in MOVES) for different road types and various average speeds to represent the vehicle operating modes on road. However, it is still not clear if the facility- and speed-specific VSP distributions are consistent temporally and spatially. For instance, is it necessary to update periodically the database of the VSP distributions in the emission model? Are the VSP distributions developed in the city central business district (CBD) area applicable to its suburb area? In this context, this study examined the temporal and spatial consistency of the facility- and speed-specific VSP distributions in Beijing. The VSP distributions in different years and in different areas are developed, based on real-world vehicle activity data. The root mean square error (RMSE) is employed to quantify the difference between the VSP distributions. The maximum differences of the VSP distributions between different years and between different areas are approximately 20% of that between different road types. The analysis of the carbon dioxide (CO2) emission factor indicates that the temporal and spatial differences of the VSP distributions have no significant impact on vehicle emission estimation, with relative error of less than 3%.Implications: The temporal and spatial differences have no significant impact on the development of the facility- and speed-specific VSP distributions for the vehicle emission estimation. The database of the specific VSP distributions in the VSP-based emission models can maintain in terms of time. Thus, it is unnecessary to update the database regularly, and it is reliable to use the history vehicle activity data to forecast the emissions in the future. In one city, the areas with less data can still develop accurate VSP distributions based on better data from other areas. 相似文献
The Quick, Easy, Cheap, Effective, Rugged, and Safe (QuEChERS) method was applied to the extraction of 14 organochlorine pesticides (OCPs) residues from commercial fruit pulps available in supermarkets in Fortaleza, Northeastern Brazil. The analyses were carried out by gas chromatography (GC), coupled to an electron-capture detector (ECD), and were confirmed by GC-tandem mass spectrometry (MS). The parameters of the analytical method, such as accuracy, precision, linear range, limits of detection and quantification, were determined for each pesticide. The results showed good linearity (R2 ≥ 0.9916) and the overall average recoveries were considered satisfactory obtaining values between 69 and 110%, RSD of 2–15 %, except for hexachlorobenzene (HCB) in açai, acerola and guava pulp samples. The OCPs were detected in guava (α–HCH; lindane) and soursop (α, β–HCH isomers) samples. The QuEChERS method and GC–ECD were successfully used to analyze OCPs in commercially available Brazilian fruit pulps and can be applied in routine analytical laboratories. 相似文献
Currently, activated coke is widely used in the removal of multiple pollutants from industrial flue gas. In this paper, a series of novel FexLayOz/AC catalysts was prepared by the incipient wetness impregnation for NH3-SCR denitrification reaction. The introduction of Fe-La bimetal oxides significantly improved the denitrification performance of activated coke at mid-high temperature, and 4% Fe0.3La0.7O1.5/AC exhibited a superior NOx conversion efficiency of 90.1% at 400 °C. The catalysts were further characterized by BET, SEM, XRD, Raman, EPR, XPS, FTIR, NH3-TPD, H2-TPR, et al., whose results showed that the perovskite-type oxide of LaFeO3 and oxygen vacancies were produced on the catalysts’ surfaces during roasting. Fe-La doping enhanced the amount of acid sites (mainly Lewis and other stronger acid sites) and the content of multifarious oxygen species, which were beneficial for NOx removal at mid-high temperature. Moreover, it was investigated that the effect of released CO from activated coke at mid-high temperature on the NOx removal through the lifetime test, in which it was found that a large amount of CO produced by pyrolysis of activated coke could promote the NOx removal, and long-term escaping of CO on the activated coke carrier did not have a significant negative impact on catalytic performance. The results of the TG-IR test showed that volatile matter is released from the activated coke while TG results showed that the weight loss rate of 4% Fe0.3La0.7O1.5/AC only was 0.0015~0.007%/min at 300–400 °C. Hence, 4% Fe0.3La0.7O1.5/AC had excellent thermal stability and denitrification performance to be continuously used at mid-high temperature. Finally, the mechanisms were proposed on the basis of experiments and characterization results.
This study investigated crystallization mechanisms for the formation of lead aluminosilicate by sintering lead stabilization with kaolin-based precursors. PbAl2Si2O8 was found to be the only stable lead aluminosilicate in low-PbO system and demonstrates its highly intrinsic resistance to acid attack in leaching test. A three-stage PbAl2Si2O8 formation mechanism was supported by the results of the changing temperature in the system. Amorphization of sintered products was observed in both PbO/kaolinite and PbO/mullite systems at 600–700°C. When the temperature was increased to 750–900°C, the crystallochemical formation of lead aluminosilicates (i.e., Pb4Al4Si3O16, Pb6Al6Si2O21, and PbAl2Si2O8) was observed. Pb4Al4Si3O16 and Pb6Al6Si2O21 were found to be the intermediate phases at 700–900°C. Finally, PbAl2Si2O8 was found to be the only crystallite phase to host Pb at above 950°C. A maximum of 80% and 96.7% Pb can be incorporated into PbAl2Si2O8 in PbO/kaolinite and PbO/mullite systems, respectively, but the final products exhibited different microstructures. To reduce environmental hazard of lead, this strategy demonstrated a preferred mechanism of immobilizing lead into PbAl2Si2O8 structure via kaolin-based precursors. 相似文献