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41.
基于互联网技术的“共享经济”不仅在众多新兴市场上创造出了经济增长点,还通过潜移默化地改变大众消费行为,对城市经济和空间产生了巨大影响。正如以Airbnb为代表的共享短租平台在冲击了传统旅游住宿业与城市住房市场的同时,也引起了城市空间的变化。为了深入了解这一现象,论文首先概述了共享短租平台的发展背景、概念与现状,阐述它所带来的影响和因此引发的争论;接着探讨了共享短租平台(以Airbnb为例)与酒店业和住房市场的关系,以及其进一步商业化可能带来的影响与问题;最后,通过分析大量实践案例得出共享短租平台与城市空间存在双向互动关系,即城市空间中的社会经济与物质环境因子决定了共享短租平台房源的空间分布特征,而共享短租平台会以旅游绅士化、商业结构改变和城市设施负担加重的方式逐渐改变城市社会经济和物质环境空间。 相似文献
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湖南盛夏两次连续性暴雨过程对比分析 总被引:1,自引:0,他引:1
利用常规气象观测资料和NECP的1°×1°再分析资料,从暴雨特征、天气背景和暴雨发生的动力、水汽、热力条件及非地转湿Q矢量等方面对2010年7月8—13日和2012年7月12—19日湖南两次大范围暴雨天气过程进行对比分析,并对暴雨造成的洪涝灾害成因进行阐述。结果表明:湖南两次暴雨过程的环流形势和水汽输送路径均存在一定程度的相似性;东北低涡和低层切变线是造成两次持续性暴雨过程的主要影响系统;850 hPa的θse高值区、垂直上升速度中心及湿Q矢量负值区与暴雨落区有较好的对应关系,对暴雨预报有一定的指示作用。第二次暴雨过程冷空气势力比第一次暴雨过程更强,低层切变线在湘北及湘中偏南地区摆动,使较强水汽辐合在中低层维持了5 d,因此第二次暴雨过程影响范围更广且持续时间更长。而第一次暴雨过程副热带高压更强盛,高、低空急流耦合作用更明显,垂直上升气流更强,高能高湿更易触发短时强降水;同时由于第一次暴雨过程开始前湖南全省降雨已经明显偏多,且强降雨带集中在湘北地区,加之受灾最严重的地区又属于地质灾害多发区,从而更易导致滑坡、崩塌和泥石流的发生。 相似文献
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Jiang-Pei Dou De-Qing Ren Yong-Tian Zhu National Astronomical Observatories / Nanjing Institute of Astronomical Optics & Technology Chinese Academy of Sciences Nanjing China Key Laboratory of Astronomical Optics & Technology Nanjing Institute of Astronomical Optics & Technology China Physics & Astronomy Department California State University Northridge Nordhoff Street Northridge California – 《中国天文和天体物理学报》2010,10(2)
We propose a high-contrast coronagraph for direct imaging of young Jupiter-like planets orbiting nearby bright stars. The coronagraph employs a steptransmission filter in which the intensity is apodized with a finite number of steps with identical transmission in each step. It should be installed on a large ground-based telescope equipped with a state-of-the-art adaptive optics system. In this case, contrast ratios around 10-6 should be accessible within 0.1 arcsec of the central star. In recent progress, a... 相似文献
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Adopting the autoregressive method for time-series modeling, we have made a study on the medium-term forecast of solar 10.7 cm radio flux (F10.7). The result of forecast experiments and the error analysis indicate that when the solar activity is at a rather low level and the 27-day periodicity of F10.7 is apparent, the autoregressive forecast method has a high accuracy and relatively ideal effectiveness, but when a large active region appears or disappears on the solar dusk, the forecast effectiveness is not ideal. This means that the autoregressive method for the time-series modeling can reflect well the 27-day periodicity of F10.7, and that it has certain applicability for building a mediumterm forecast model of F10.7. By comparing the forecast results in the period from 21th September 2005 to 7th June 2007, it is demonstrated that the accuracy of the autoregressive forecast method is equivalent to that of the forecast made by the American Air Force. 相似文献
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Sea ice growth and consolidation play a significant role in heat and momentum exchange between the atmosphere and the ocean. However, few in situ observations of sea ice kinematics have been reported owing to difficulties of deployment of buoys in the marginal ice zone (MIZ). To investigate the characteristics of sea ice kinematics from MIZ to packed ice zone (PIZ), eight drifting buoys designed by Taiyuan University of Technology were deployed in the open water at the ice edge of the Canadian Basin. Sea ice near the buoy constantly increased as the buoy drifted, and the kinematics of the buoy changed as the buoy was frozen into the ice. This process can be determined using sea ice concentration, sea skin temperature, and drift speed of buoy together. Sea ice concentration data showed that buoys entered the PIZ in mid-October as the ice grew and consolidated around the buoys, with high amplitude, high frequency buoy motions almost ceasing. Our results confirmed that good correlation coefficient in monthly scale between buoy drift and the wind only happened in the ice zone. The correlation coefficient between buoys and wind was below 0.3 while the buoys were in open water. As buoys entered the ice zone, the buoy speed was normally distributed at wind speeds above 6 m/s. The buoy drifted mainly to the right of the wind within 45° at wind speeds above 8 m/s. During further consolidation of the ice in MIZ, the direct forcing on the ice through winds will be lessened. The correlation coefficient value increased to 0.9 in November, and gradually decreased to 0.7 in April. 相似文献
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哈拉湖岩芯XRF扫描元素统计分析及其环境意义 总被引:3,自引:0,他引:3
青藏高原东北缘高山湖泊哈拉湖是位于季风与西风影响的交汇带的封闭深水湖泊,是区域环境和气候变化的良好记录载体。目前对该湖的研究还较少,缺乏对沉积物中元素环境意义的系统认识。通过高分辨率XRF岩芯扫描,用相关、聚类和因子分析的方法对哈拉湖沉积岩芯地球化学元素进行分析。结果显示Ti、K、Si、Al、Fe、Mn等元素变化一致,相关性高,归为同一类,即径流输入的陆源碎屑组分,反映了流域水文状况如径流量的变化。Sr、Zr元素相关性高,为赋存在粗颗粒沉积物中的元素,根据哈拉湖实际,应为冬季湖泊冰面风力搬运,反映了湖区冬季风力强度的变化。Ca元素既与径流输入元素总体变化一致,也与Sr、Zr元素显著相关,且在第一和第二主成分(径流和风力)上的载荷相当,表明哈拉湖沉积物中的碳酸盐既有粗颗粒的外源碎屑,也有湖泊自生的组分,这在利用碳酸盐进行地球化学研究时应重视,注意去除外源碎屑碳酸盐的影响。可溶元素S和Cl可能反映了入湖水量与蒸发对比情况,与湖泊盐度有关。 相似文献
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Abstract Zinc (Zn) and copper (Cu) concentrations were determined in the tissues (muscle, stomach, liver, gills, skin, and gonads) of five commercial fish species (mullet Liza haematocheilus, flathead Platycephalus indicus, mackerel Scomberomorus niphonius, silver pomfret Pampus argenteus, and sea bass Lateolabrax japonicus) from Laizhou Bay in the Bohai Sea. Metal bioaccumulation was highest in the metabolically active tissues of the gonads and liver. Bioconcentration factors for Zn were higher in all tissues (gonads 44.35, stomach 7.73, gills 7.72, liver 5.61, skin 4.88, and muscle 1.63) than the corresponding values for Cu (gonads 3.50, stomach 3.00, gills 1.60, liver 5.43, skin 1.50, and muscle 0.93). Mackerel tissues accumulated metal to higher concentrations than did other fish species, but bioaccumulation levels were not significantly correlated with the trophic levels of the fish. Zn and Cu concentrations in the tissues were generally negatively correlated with fish length, except for a few tissues of sea bass. Risk assessment based on national and international permissible limits and provisional tolerances for weekly intake of Zn and Cu revealed that the concentrations of these two metals in muscle were relatively low and would not pose hazards to human health. 相似文献