Particulate matter pollution in Kunshan High-Tech zone: Source apportionment with trace elements, plume evolution and its monitoring.

Particulate matter (PM) in the Kunshan High-Tech zone is studied during a three-month campaign. PM and trace elements are measured by the online pollution monitoring, forecast-warning and source term retrieval system AS3. Hourly measured concentrations of PM10, PM2.5 and 16 trace elements in the PM2.5 section (Ca, Pb, Cu, Cl, V, Cr, Fe, Ti, Mn, Ni, Zn, Ga, As, Se, Sr, Ba) are focused. Source apportionment of trace elements by Positive Matrix Factorization modeling indicates that there are five major sources, including dust, industrial processing, traffic, combustion, and sea salt with contribution rate of 23.68%, 21.66%, 14.30%, 22.03%, and 6.89%, respectively. Prediction of plume dispersion from concrete plant and traffic emissions shows that PM10 pollution of concrete plant is three orders of magnitude more than that of the traffic. The influence range can extend to more than 3km in 1hr. Because the footprint of the industrial plumes is constantly moving according to the local meteorological conditions, the fixed monitoring sites scattered in a few hundred meters haven't captured the heaviest pollution plume at the local scale of a few km2. As a more intensive monitoring network is not operationally possible, the use of online modeling gives accurate and quantitative information of plume location, which increases the spatial pollution monitoring capacity and improves the understanding of measurement data. These results indicate that the development of the AS3 system, which combines monitoring equipment and air pollution modeling systems, is beneficial to the real-time pollution monitoring in the industrial zone.

The sensing characteristics of plasmonic waveguide with a ring resonator.

A surface plasmon polaritons (SPPs) refractive index sensor which consists of two metal-insulator-metal (MIM) waveguides coupled to each other by a ring resonator is proposed. The transmission properties are numerically simulated by finite element method. The sensing characteristics of such structure are systematically analyzed by investigating the transmission spectrum. The results indicate that there exist three resonance peaks in the transmission spectrum, and all of which have a linear relationship with the refractive index of the material under sensing. Through the optimization of structural parameters, we achieve a theoretical value of the refractive index sensitivity as high as 3460nmRIU(-1). Furthermore, this structure can also be used as a temperature sensor with temperature sensitivity of 1.36nm/°C. This work paves the way toward sensitive nanometer scale refractive index sensor and temperature sensor for design and application.

Transverse-electric and transverse-magnetic mode slow light propagation in a two-dimensional photonic crystal waveguide.

A two-dimensional photonic crystal waveguide structure is designed for both TE- and TM-mode slow light propagation. The minimum group index of the waveguide for TE and TM modes can reach to 137.8 and 126.4, and the two polarizations have the same slow light frequency region. The designed structure can provide a large bandwidth range with very low group velocity dispersion for both TE and TM modes. The transmission property investigation for a suspended two-dimensional slab photonic crystal waveguide (PCW) indicates that such slow light character may be retained when perfect reflectors can be fixed on the horizontal surfaces of the slab. Such high group index for both TE and TM modes in two-dimensional PCWs is, to the best of our knowledge, first reported here, and may provide some useful guides for slow light research in theory.