Browsing by Author "Zhang, Xiaowei"

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    The Effects of Conservation Easements on Land Values
    Zhang, Xiaowei (Virginia Tech, 2004-05-05)
    The Conservation easement has become a popular tool for land protection in the past few decades. Whether this development restriction will necessarily decrease the land value is an empirical question. This study employs a hedonic pricing approach to test empirically the effects of conservation easements on land values. The econometric results indicate that conservation easements can slightly increase the land values, but the effect is statistically insignificance. Considering the limited dataset, the interpretation of the results warrant some caution.
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    High-performance inertial impaction filters for particulate matter removal
    Zhang, Xiaowei; Zhang, Wei; Yi, Mingqiang; Wang, Yingjie; Wang, Pengjun; Xu, Jun; Niu, Fenglei; Lin, Feng (Springer Nature, 2018-03-19)
    Airborne particulate matter (PM) is causing more and more serious air pollution and threatening the public health. However, existing air filter technologies with the easy-to-block manner can rarely meet the requirements of high-performance PM filters. Here we propose a conceptually new type of inertial impaction filters for rapidly high-efficiency PM removal. Under the airflow velocity of 8.0 m/s, the real inertial impaction filters show high PM removal efficiencies of up to 97.77 +/- 1.53% and 99.47 +/- 0.45% for PM2.5 and PM10, respectively. Compared with the traditional air filters reported previously, the inertia impaction filters exhibit extremely low pressure drop of 5-10 Pa and high quality factor (QF) values of 0.380 Pa-1 and 0.524 Pa-1 for PM2.5 and PM10, respectively. These greatly improved QF values are achieved through a series of inertial separation processes. The feature dimension of filtration channel is dozens of times larger than PM average size, which greatly decreases airflow resistance. Particularly, this inertial structure can be made of various types of materials, which shows great potential for low-cost fabrication of large-area devices. As a stand-alone device or incorporated with the existing PM air filter, this inertial impaction filter will bring great benefits to the public health.