Fenhuan Yang

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High energy linear colliders require very small beams at the interaction point to produce high luminosities, and these beams must be measured and monitored. We have developed and tested a technique where the profile can be obtained from an extension of pinhole camera optics using thick, single sided collimators and slits. Very high resolutions (a few nm)(More)
Adverse health effects are associated with exposure to atmospheric particulate matter (PM), which carry various chemical constituents and induce both exogenous and endogenous oxidative stress. This study investigated the spatial and seasonal variability of PM-induced ROS at four sites with different characteristics in Hong Kong. Cytotoxicity, exogenous and(More)
One-week integrated PM2.5 samples were collected over four years (2005–2008) at a pair of sites, one rural and one urban site, in the area of Beijing, China. Weekly organic and elemental carbon (OC and EC) concentrations from these samples were measured to investigate their atmospheric concentrations, temporal variation patterns and the factors influencing(More)
Metals in atmospheric particulate matter (PM) have been associated with various adverse health effects. Different factors contributing to the characterization and distribution of atmospheric metals in urban environments lead to uncertainty of the understanding of their impact on public health. However, few studies have provided a comprehensive picture of(More)
An X-band circularly polarized reflectarray antenna with an offset feed is designed, fabricated, and measured. The proposed design features the use of split square ring elements with a modified element rotation technique for phase compensation, which allows the rotation of the slot instead of the element itself. This is crucial in single-layer multiband(More)
This study presents the development and evaluation of a next generation air monitoring system with both laboratory and field tests. A multi-parameter algorithm was used to correct for the impact of environmental conditions on the electrochemical sensors for carbon monoxide (CO) and nitrogen dioxide (NO2) pollutants. The field evaluation in an urban roadside(More)
Information overload in the modern society calls for highly efficient recommendation algorithms. In this letter we present a novel diffusion based recommendation model, with users’ ratings built into a transition matrix. To speed up computation we introduce Green function method. The numerical tests on a benchmark database show that our prediction is(More)