The Fast Evolution of Vehicle Emissions from Roadway (FEVER) study was undertaken to strategically measure pollutant gradients perpendicular to a major highway north of Toronto, Canada. A case study period was analyzed when there was an average perpendicular wind direction. Two independent, fast response measurements were used to infer rapid organic aerosol (OA) growth on a spatial scale from 34 m to 285 m at the same time as a decrease was observed in the mixing ratio of primary emitted species, such as CO2 and NOx. An integrated organic gas and particle sampler also showed that near the highway, the aerosol had a larger semivolatile fraction than lower volatile fraction, but over a relatively short distance downwind of the highway, the aerosol transformed to being more low volatile with the change being driven by both evaporation of semivolatile and production of lower volatile organic aerosol. A new 1-D column Lagrangian atmospheric chemistry model was developed to help interpret the measured increase in the OA/CO2 curve from 34 m to 285 m downwind of highway, where the refers to background-corrected concentrations. The model was sensitive to the assumptions for semivolatile organic compounds (SVOCs). Different combinations of SVOC emissions and background mixing ratios were able to yield similar model curves and reproduce the observations. Future measurements of total gas-phase SVOC in equilibrium with aerosol both upwind and downwind of the highway would be helpful to constrain the model.
Extraction and transmission of compact descriptors are of great importance for next-generation mobile visual search applications. Existing visual descriptor techniques mainly compress visual features into compact codes of fixed bit rate, which is not adaptive to the bandwidth fluctuation in wireless environment. In this letter, we propose a Rate-adaptive Compact Fisher Codes (RCFC) to produce a bit rate scalable image signature. In particular, RCFC supports fast matching of descriptors based on Hamming distance; meanwhile, low memory footprint is offered. Extensive evaluation over benchmark databases shows that RCFC significantly outperforms the state-of-the-art and provides a promising descriptor scalability in terms of bit rates versus desired search performance.
Extraction and transmission of compact descriptors are of great importance for next-generation mobile visual search applications. Existing visual descriptor techniques mainly compress visual features into compact codes of fixed bit rate, which is not adaptive to the bandwidth fluctuation in wireless environment. In this letter, we propose a Rate-adaptive Compact Fisher Codes (RCFC) to produce a bit rate scalable image signature. In particular, RCFC supports fast matching of descriptors based on Hamming distance; meanwhile, low memory footprint is offered. Extensive evaluation over benchmark databases shows that RCFC significantly outperforms the state-of-the-art and provides a promising descriptor scalability in terms of bit rates versus desired search performance.
This paper proposes a filter realised using only lumped-element components, implemented as a highly selective bandpass filter suitable for lowpass delta-sigma (LPΔΣ) RF transmitters. The proposed filter is characterised by low insertion loss, high selectivity and a transfer function tailored for filtering the close-up out-of-band noise of LPΔΣ RF transmitters. The circuit design is based on a modified loaded-stub ring-resonator structure, however, implemented using 4 π-shape lumped-element resonators with LC tanks. The measurements show good agreement with simulation and the proposed filter provides a fractional 3-dB bandwidth of 14.3 %, insertion loss of less than 1.6 dB, suppression of more than 18 dB on both sides of the desired band, and a sharp cut-off frequency response. This filter is combined with the delta-sigma transmitter to show the effective reduction of the out-of-band quantisation noise signals.
As two obligatory intermediates of denitrification, both NO and N2O had harmful environmental and biological impacts. An aerobic denitrifying bacterial strain PCN-1 was newly isolated and identified as Pseudomonas stutzeri, which was capable of high efficient nitrogen removal under aerobic condition with maximal NO and N2O accumulation as low as 0.003% and 0.33% of removed NO3 -N, respectively. Further experiment taking nitrite as denitrifying substrate indicated similar low NO and N2O emission of 0.006% and 0.29% of reduced NO2 -N, respectively. Reverse transcription-polymerase chain reaction (RT-PCR) analysis revealed that the coordinate expression of denitrification gene nirS (for cytochrome cd(1) nitrite reductase), cnorB (for NO reductase) and nosZ (for N2O reductase) was the fundamental reason of low NO and N2O accumulation. Activated sludge system bioaugmented by strain PCN-1 demonstrated a significant reduction of NO and N2O emission from wastewater during aerobic denitrification, implied great potential of PCN-1 in practical applications. (C) 2014 Elsevier Ltd. All rights reserved.
