基于网络游记的城市旅游流网络结构演化研究——以北京市为例

采用网络游记文本数据,结合爬虫技术和社会网络分析方法,分析北京市"十二五"和"十三五"时期城市旅游客流网络结构的演变特征。结果表明:①城市旅游流网络结构存在不均衡性,城市历史文化遗产节点的的影响控制能力强,新兴旅游吸引物的集聚能力相对较弱,受不同类型节点的路径依赖效应的影响,这种差异存在动态扩大特征。②城市旅游流网络结构呈现显著的等级分层结构和节点分散分布特征,传统游憩场所是城市旅游流的核心节点,外围发育的旅游节点较分散且规模能级提升空间较大。③城市旅游流拥有显著的赋能效应、倒逼效应和联通效应。     

Seasonal acceleration of the rate of total ozone decreases over Central Europe: impact of tropopause height changes

Total ozone data from some European stations have been analyzed to detect the ozone decrease in different seasons from 1979 to 1995. The differences between the winter–spring (December–March) and summer (May–August) total ozone means have decreased distinctly during the last three decades, by 10 Dobson Units per decade, showing that the winter–spring decrease is significantly stronger than the summer one. Applying a multiple regression model to the monthly means of tropopause height, positive trends in the summer and winter–spring seasons have been found, especially since 1979. This corresponds to the accelerating ozone decrease then. The possibility of using tropopause height variations as an indicator of dynamical variability in the total ozone trend model is discussed. The total ozone response to the changes of tropopause height seems to be independent of timescale over which the tropopause-total ozone relationship has been examined (month-to-month, interannual). The total ozone trends, as well as the accelerated rate of ozone decrease since 1979 in the winter–spring and summer seasons, respectively, are reduced by about 0.5–1% per decade after inclusion of the tropopause height effect on the ozone model.     

用于数字测图的摄影测量数据库系统

本文介绍了一种面向数字测图系统的摄影测量数据库，着重讨论了该数据库的基本框架及数据结构。尤其是对数据块动态串作了深入的探讨。实践表明，这种数据库的设计方案是可行的。     

黄河1922～1932年连续11年枯水段的分析研究

本文根据大量实测及历史资料,论证了黄河上游存在与中游同步的1922～1932年连续11年枯水段,该枯水段的出现机率为200年一遇。建议以1951～1975年水文系列作为黄河水资源规划和水利计算的代表系列。     

板钉连接CFST柱-RC梁节点梁端塑性铰区受力性能数值模拟

建立竖板-栓钉连接钢管混凝土（CFST）柱-钢筋混凝土（RC）梁节点试件（SSJD）拟静力加载试验有限元模型,并在节点损伤情况、梁端荷载-位移曲线等数值模拟结果与试验结果吻合较好的基础上,进一步开展了RC梁混凝土强度、配筋率ρs和连接竖板长度Lb及界面连接情况等对CFST柱-RC梁节点梁端塑性铰区域力学性能的影响。研究结果表明,RC梁混凝土强度对试件SSJD塑性铰区域受力性能的影响较小;适筋范围内RC梁配筋率增加可适当提高试件SSJD承载力和延性;随着连接竖板长度的增加,梁端塑性铰区域外移,梁破坏荷载增大;本研究给出的RC梁与CFST柱之间的界面抗剪承载力模拟值与计算值吻合较好,可用于界面抗剪设计。     

东北北部冷暖旱涝趋势的初步研究

根据１９５１～１９９９年黑龙江省代表站的历年逐月的气温、降水量资料,用计算趋势系数的方法,研究了东北北部冷暖旱涝趋势的问题。结果指出：进入９０年代,东北北部夏季气温变暖现象更加显著;但过渡季节气温变暖的趋势已经结束;旱涝趋势的变化比冷暖趋势的变化更为复杂,具有不同的季节特征和地域特征。     

改进的传染型余震序列模型

将有限幂律公式（LPL）应用到传染型余震序列模型（ETAS）中，并对原ETAS模型加以改进。以台湾集集地震早期余震序列为例，对原ETAS模型与改进的ETAS模型进行了对比分析，结果表明改进的ETAS模型要优于原ETAS模型。     

Old stellar population synthesis： new age and mass estimates for Mayall Ⅱ = G1

Mayall Ⅱ = G1 is one of the most luminous globular clusters （GCs） in M31. Here, we determine its age and mass by comparing multicolor photometry with theoretical stellar population synthesis models. Based on far- and near-ultraviolet GALEX photometry, broad-band UBVRI, and infrared JHKs 2MASS data, we construct the most extensive spectral energy distribution of G 1 to date, spanning the wavelength range from 1538 to 20 000A. A quantitative comparison with a variety of simple stellar population （SSP） models yields a mean age which is consistent with G1 being among the oldest building blocks of M31 and having formed within ～1.7 Gyr after the Big Bang. Irrespective of the SSP model or stellar initial mass function adopted, the resulting mass estimates （of order 10^7M⊙） indicate that GI is one of the most massive GCs in the Local Group. However, we speculate that the cluster＇s exceptionally high mass suggests that it may not be a genuine GC. Our results also suggest that G1 may contain, on average, （1.65±0.63） × 10^2L⊙ far-ultraviolet-bright, hot, extreme horizontal-branch stars, depending on the adopted SSP model. In addition, we demonstrate that extensive multi-passband photometry coupled with SSP analysis enables one to obtain age estimates for old SSPs that have similar accuracies as those from integrated spectroscopy or resolved stellar photometry, provided that some of the free parameters can be constrained independently.     

Magnetotelluric sounding results in eastern Tibetan Plateau

The results of Zayü-Qingshuihe MT sounding profile carried out in eastern Tibetan Plateau are presented in this paper. Using 2-D RRI method, the resistivity distribution with depth is obtained along the profile. It is featured by the resistivity zones in the horizontal direction and layers in the vertical direction. The Bangong-Nujiang suture zone and Jinshajiang suture zone are both important electrical conductivity-separating zones in the plateau, and the former is a zone with relatively low resistivity while the latter is an electrical conductivity gradient zone. The highly electrical conductive bodies in the mid and lower crust of northern Qiangtang and Bayan Har Terrain might be caused by regional melting due to shear heating during the process of subduction in tectonic evolution.