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AN INSIGHT ON DRIVERS OF LAND USE CHANGE AT REGIONAL SCALE 被引量:2
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作者 SHAO Jing-an WEI Chao-fu XIE De-ti 《Chinese Geographical Science》 SCIE CSCD 2006年第2期176-182,共7页
The studies of driving forces of regional land use change (LUC) are to reveal the real motivation behind the LUC and its interacting mechanism, so as to simulate and predict the process of LUC. Presently, studies root... The studies of driving forces of regional land use change (LUC) are to reveal the real motivation behind the LUC and its interacting mechanism, so as to simulate and predict the process of LUC. Presently, studies rooting from different natural and socio-economic backgrounds and from different scales have deepened the people’s understanding and cognition to driving forces of regional LUC. Biophysical driving forces are relatively stable, and have the cumulating effects. Human driving forces are relatively active, and are main driving forces of short-term regional LUC. Existing regional LUC models can answer the three main problems: which contribution (why), which location (where) and what rate (when). But, regional land use system is defined as the self-organized system, usually affected by the cri- tical value area and sudden change, and controlled by different stages. To reduce the impact of critical threshold and break on land use system, the studies of LUC driving forces will aim at following priority areas: data linkage between remote sensing and no-remote sensing data; underlying driving force identification; driving factor quantification; driving factor scale dependence; and driving process integration simulation. 展开更多
关键词 land use change driving forces driving mechanism process simulation regional scale
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First observations of the water masers with the Urumqi 25m radio telescope
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作者 郑兴武 加尔肯 周建军 《Science China Mathematics》 SCIE 2001年第10期1356-1360,共5页
A new radio spectral receiving system has been installed on the 25 m radio telescope of the Urumqi Astronomical Observatory. The back end is a surface acoustic wave chirp transform spectrometer (SAW CZT), used for the... A new radio spectral receiving system has been installed on the 25 m radio telescope of the Urumqi Astronomical Observatory. The back end is a surface acoustic wave chirp transform spectrometer (SAW CZT), used for the first time in radio astronomy. The calibration of the line observations has carefully been investigated for the new-type spectrometer. In order to test the feasibility of the prototype spectrometer, we observed water maser emission from a number of known Galactic sources. We describe the observed spectra of W49N, W3(OH), 2248+600 and 1909+090. We found that W49N spectrum showed high-velocity features ranging from -330 to 146 km s-1. In comparison with the spectra observed by Medicina, the feature at the LSR velocity -52 km s-1 in the W3(OH) presented the rapid variation in flux density. 展开更多
关键词 astronomical technique-calibration of the line observation H II regions-ISM: masers
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