A New Angular Light Scattering Measurement of Particulate Matter Mass Concentration for Homogeneous Spherical Particles

Under the condition of ultra-low emission for power plants, the particulate matter concentration is significantly lower than that of typical power plants a decade ago, which posed new challenges for the particulate matter monitoring of stationary emission. The monitoring of particulate matter mass concentration based on ensemble light scattering has been found affected by particle size. Thus, this study develops a method of using the scattering angular distribution to obtain the real-time particle size, and then correct the particulate matter concentration with the real-time measured particle size. In this study, a real-time aerosol concentration and particle size measurement setup is constructed with a fixed detector at the forward direction and a rotating detector. The mass concentration is measured by the fixed detector, and the particle size is measured from the intensity ratio of the two detectors. The simulations show that the particle size has power law functionality with the angular spacing of the ripple structure according to Mie theory. Four quartz aerosols with different particle size are tested during the experiment, and the particle size measured from the ripple width is compared with the mass median size measured by an electrical low pressure impactor (ELPI). Both techniques have the same measurement tendency, and the measurement deviation by the ripple width method compared with ELPI is less than 15%. Finally, the measurement error of the real-time mass concentration is reduced from 38% to 18% with correction of the simultaneously measured particle size when particle size has changed.

Models on Real-Time State Identification for Unban Traffic Based on Fixed Detector

For the advantages and disadvantages of the traffic state identification based on fixed detector, a kind of method on the real-time state identification for the unban traffic was presented in order to improve accuracy and practical level of the traffic state identification. From analysis on detectors distribution and data collection methods, this paper carried out data preprocessing which collected from fixed detectors, then established the identification methods and thresholds for traffic state, developed the evaluation models of urban traffic congestion. Finally, the practicality of models was validated according to the traffic data collected by fixed detectors on typical roads in Qingdao city. The results show that the traffic state identification of the models is effective and with high precision.

Configured detectors in STEM holography

In Gabor's in-line holography, the transmitted plane wave and the beam diffracted by the specimen form an interference pattern (hologram). In a STEM instrument, when the incident probe is scanning over the specimen, the hologram translates across the illuminated portion of the detector plane. The signal produced by the detector can be represented by integrating the product of the hologram with some detector sensitivity function. It had be pointed out long ago by Veneklasen that scanning the hologram over a fixed detector has in effect performed a reconstruction of the hologram simultaneously, and with some specially designed detector the aberration introduced by the objective lens is correctable. This scheme has been reraised recently and some preliminary work will be reported here.

Energy-dispersive diffuse X-ray scattering apparatus

A design is presented of apparatus suitable for energy-dispersive diffuse X-ray scattering in which the sample is oriented on a three-circle cradle within a vacuum chamber. The apparatus alignment procedures are discussed and a method given for finding the relevant orientation matrix under the conditions of Laue scattering to a fixed detector. The method also finds the zero positions of the orienter and is not confined to diffuse-scattering applications.