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991.
992.
文中讨论了归一化、无量纲的参量S,它可以较好地描述震磁前兆信息量。分析研究了1993年11月18日宝坻M=4.5的地震前后地磁变化所对应的信息量S,结果表明,S可以较好地反映震磁前兆现象。因此,以震磁前兆信息量进行地震预测研究是有意义的。 相似文献
993.
994.
RECONSTRUCTING MIDDLE-TIBET CLIMATE DURING THE LAST 600 YEARS BY DENDROCLIMATOLOGICAL METHOD* 下载免费PDF全文
Based on four tree-ring chronologies which was analyscd with appropriate collection and accurate dating in the middle Tibetan Plateau,an essential procedure on reconstruction of past climate has been pointed out in this paper.First,the response function of each dendrochronology has been built and used to estimate how ring-width growth responds to variations in monthly climatic change.Second,the climate factors which could be produced with different tree-ring series have been selected.Then,the transfer function equation,including a new set of orthogonal variables,can be used to reconstruct local past temperature or precipitation.It should be emphasized that prior growth has been considered in the relationship between climate factor and tree-ring chronology,Besides,some different periods for calibration and verification have been divided.And some statistics and other kinds of proxy data have been adopted as test approaches.As a result,the variations of air temperature during the last 600 years and precipitation during the last 340 years were reconstructed by combining the same types of tree-ring series in the middle Tibet. 相似文献
995.
面向旅游社交媒体大数据的分析和挖掘,该文提出一种旅游领域多主题情感词典的构建方法:首先,通过自然语言处理、机器学习,快速提取景区评价数据中旅游主题及其情感倾向,然后基于旅游多主题字典定义覆盖景区9类主题及细粒度种子主题词,最后针对景区情感倾向分析问题,根据词共现模型筛选与主题词典构成搭配的情感词,构建面向旅游领域的多主题情感词典.以海南省A级景区为例,基于上述构建的旅游领域多主题情感词典和景区网络关注度计算结果,对游客评论文本进行信息挖掘,并进一步结合GIS时空数据挖掘及网络关注度分析等方法,分析研究区域旅游景区游览信息的时空分布特征.结果表明,该文方法能有效监测景区各项主题的好评程度时空变化,验证了该方法的实用性和有效性. 相似文献
996.
Mingjin?Zhan Xiucang?Li Hemin?Sun Jianqing?Zhai Tong?Jiang Yanjun?WangEmail author 《Acta Meteorologica Sinica》2018,32(1):99-112
We used daily maximum temperature data (1986–2100) from the COSMO-CLM (COnsortium for Small-scale MOdeling in CLimate Mode) regional climate model and the population statistics for China in 2010 to determine the frequency, intensity, coverage, and population exposure of extreme maximum temperature events (EMTEs) with the intensity–area–duration method. Between 1986 and 2005 (reference period), the frequency, intensity, and coverage of EMTEs are 1330–1680 times yr–1, 31.4–33.3°C, and 1.76–3.88 million km2, respectively. The center of the most severe EMTEs is located in central China and 179.5–392.8 million people are exposed to EMTEs annually. Relative to 1986–2005, the frequency, intensity, and coverage of EMTEs increase by 1.13–6.84, 0.32–1.50, and 15.98%–30.68%, respectively, under 1.5°C warming; under 2.0°C warming, the increases are 1.73–12.48, 0.64–2.76, and 31.96%–50.00%, respectively. It is possible that both the intensity and coverage of future EMTEs could exceed the most severe EMTEs currently observed. Two new centers of EMTEs are projected to develop under 1.5°C warming, one in North China and the other in Southwest China. Under 2.0°C warming, a fourth EMTE center is projected to develop in Northwest China. Under 1.5 and 2.0°C warming, population exposure is projected to increase by 23.2%–39.2% and 26.6%–48%, respectively. From a regional perspective, population exposure is expected to increase most rapidly in Southwest China. A greater proportion of the population in North, Northeast, and Northwest China will be exposed to EMTEs under 2.0°C warming. The results show that a warming world will lead to increases in the intensity, frequency, and coverage of EMTEs. Warming of 2.0°C will lead to both more severe EMTEs and the exposure of more people to EMTEs. Given the probability of the increased occurrence of more severe EMTEs than in the past, it is vitally important to China that the global temperature increase is limited within 1.5°C. 相似文献
997.
1996年黄河尾闾改道以来水下三角洲的演变 总被引:1,自引:0,他引:1
根据1996-2004年黄河三角洲滨海断面的实测水深资料,总结清水沟流路自清8汊改道以来,现行黄河口水下三角洲平面和剖面演变特点。结果表明:水下三角洲的地形演变与河口区的水流动力相适应.三角洲的演变是一个动态反馈过程。在新的入海水沙通量变化形势下,应当运用系统的观点,从“动力-泥沙-地形”系统的角度研究三角洲演变的机理模型,为黄河大型水库联合调水调沙和河口治理提供技术支持。 相似文献
998.
从突发危机事件、旅游生态风险、旅游经济风险、旅游文化风险、旅游社会风险、旅游安全风险6个方面遴选出42项指标构建区域旅游风险因素识别指标体系。采用未确知数学方法、专家咨询法,从风险可能性和风险危害性两个方面构建区域旅游风险危险性评价模型,并对湖北省恩施土家族苗族自治州旅游发展中的风险进行综合评价。结果表明:在恩施州所面临的6大类旅游风险中,危险性程度最高的是旅游经济风险,其次是旅游文化风险。在42项风险因素中,自然灾害、旅游发展战略失误及盲目旅游开发导致的长期利益受损、旅游业导致的民族文化商品化/原真性丧失、旅游业导致的交通及人口拥挤等,对恩施州而言是危险性程度最高的几项风险因素。 相似文献
999.
本文应用任意3a中850hPa上的风及500hPa和地面气象资料,对台湾海峡地区出现低空急流的天气气候特征,形成急流的天气背景及其影响下的天气进行初步分析。结果表明,台湾海峡地区850hPa低空急流具有明显的季风特征和特定的地理影响。 相似文献
1000.
F. Benjamin Zhan 《国际地球制图》2013,28(3):77-81
Abstract Results of a survey to find out whether the GIS program in the Department of Geography at Southwest Texas Stare University (SWT) has served its graduates well are presented. In recent years, a considerable amount of effort has been given to the development of strategies for expanding the existing horizon of GIS education, integrating existing programs, and improving the ways in which GIS education is delivered. This study takes a different approach and seeks to get input from geography graduates who have secured a job in the real world for improving a university GIS program. Based on 26 responses to the survey, employment categories of SWT geography graduates are examined first. Then, geography courses that are considered most helpful in career development by the survey participants are identified. Third, useful GIS courses and essential skills required by the marketplace in the real world as suggested by the survey participants are discussed. It is clear from the results of the survey that the geography program at SWT in general has served its graduates well. Results from the survey also clearly indicate that GIS skills are useful in the career development of most geography graduates, particularly for those who have a concentration area in either GIS/Cartography, Resource and Environmental Studies, or Urban and Regional Planning. 相似文献