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利用2010年衡阳市4个区550份问卷调查和实地考察结果,根据大型连锁超市微观区位的客观规律,分析了衡阳市香江百货7家连锁分店的空间结构和区位特征,认为大型连锁超市区位选择是消费者购物偏好、区位因素以及商区环境3种区位指向共同作用的必然结果,并利用调研数据和消费引力模型对7家连锁超市的区位选址进行了实证分析和评价.最后,针对地方性中心城市大型连锁超市区位选择中的一般规律和不和谐趋势,从多角度探讨了大型连锁超市区位选择的若干对策,为政府制定城市发展规划和企业合理布局超市网点提供借鉴. 相似文献
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柴达木盆地植被覆盖度的分析与模拟——空间自相关方法的运用(英文) 总被引:3,自引:0,他引:3
Relationship between vegetation and environmental factors has always been a major topic in ecology, but it has also been an important way to reveal vegetation’s dynamic response to and feedback effects on climate change. For the special geographical location and climatic characteristics of the Qaidam Basin, with the support of traditional and remote sensing data, in this paper a vegetation coverage model was established. The quantitative prediction of vegetation coverage by five environmental factors was initially realized through multiple stepwise regression (MSR) models. However, there is significant multicollinearity among these five environmental factors, which reduces the performance of the MSR model. Then through the introduction of the Moran Index, an indicator that reflects the spatial auto-correlation of vegetation distribution, only two variables of average annual rainfall and local Moran Index were used in the final establishment of the vegetation coverage model. The results show that there is significant spatial autocorrelation in the distribution of vegetation. The role of spatial autocorrelation in the establishment of vegetation coverage model has not only improved the model fitting R2 from 0.608 to 0.656, but also removed the multicollinearity among independents. 相似文献
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Jia Zhang Sheng-Bang Qian Soonthornthum Boonrucksar 《Chinese Astronomy and Astrophysics》2009,33(3):279-286
The orbital period variations of the Algol-type semidetached binary UW Vir are analyzed. It is shown that in addition to a long-term rapid increase (dP/dt = + 1.37 × 10−6 day/year), its orbit period has a variation with the period of 62.3 years. Based on the basic physical parameters given by Brancewicz and Dworak in 1980, the physical mechanisms causing the orbital period variations are investigated. The analysis indicates that the periodical variation of orbital period can be interpreted by the light-travel time effect due to the presence of a third body with the mass of M3 ≥ 0.94 M. As no observational information has been reported for this tertiary component, it might be a compact object (e.g., a white dwarf). The long-term increase of orbital period can be explained in terms of the mass transfer from the secondary to the primary component (dM2/dt = 1.43 × 10−7 M/year). This is in agreement with the semidetached configuration of the system with a lobe-filling secondary component. But according to the evolution theory of binaries, the Algol-type semidetached binary UW Vir should be at the evolutionary stage of slow mass transfer on the nuclear-reaction timescale of the secondary component. However, the analysis shows that the timescale for the periodical variation of orbital period is much shorter than the nuclear-reaction timescale of the secondary component, but close to the thermodynamic timescale of the secondary. This reveals that: (1) This binary system is at the evolutionary stage of rapid mass transfer on the thermodynamic timescale of the secondary component; or (2) The circumstellar matter of the system makes a contribution to the rapid increase of orbital period via the angular momentum transfer. 相似文献
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濮阳市0 cm地温变化特征及成因分析 总被引:5,自引:1,他引:4
利用线性分析方法和相关分析方法,分析了濮阳近50年地面温度的变化倾向率及成因。月平均地面温度变化趋势具有明显的阶段性,12月至翌年4月呈升温趋势,5~11月呈降温趋势,其变化倾向率分别为0.01~0.32℃/10a和-0.04~-0.83℃/10a,年平均地面温度变化倾向率为-0.23℃/10a;各月地面平均最高温度的变化倾向率,11月为0.01℃/10a,其余月份则为-0.46~-2.16℃/10a,年变化倾向率为~0.23℃/10a;各月地面平均最低温度的变化倾向率,11月为-0.02℃/10a,其余月份则为0.09~0.76℃/10a,年变化倾向率为0.34℃/10a;各月平均地气温差的变化倾向率为-0.17~-0.66℃/10a,年变化倾向率为-0.35℃/10a。当地地面平均最高温度呈逐年递减趋势,地面平均最低温度呈逐年递增趋势,地面平均最高温度的递减趋势远大于平均最低温度的递增趋势,因此,年平均地面温度呈逐年递减趋势。地气温差逐年递减,大气稳定度增强,不利于近地层污染物和水汽扩散,由此带来轻雾日数增多,空气污染加重。日照时数减少,地面受太阳直接辐射减少,是地面温度趋降的直接原因,空气湿度和降水量趋增、空气污染加重等要素的变化,是地面温度趋降的间接原因。 相似文献
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