核电站温排水遥感定量监测方法研究

以红沿河核电站附近海域为研究对象,基于2014年到2017年获取的Landsat-8卫星遥感影像数据,对核电站温排水空间等级分布特征监测技术进行了研究。首先,利用MCSST(McClain Sea Surface Temperature)温度信息提取模型,计算研究区海表温度(Sea Surface Temperature,SST)数据;再依据海湾平均温度法,计算出海面基准温度;其次,进行差值计算,根据温升强度等级,得到研究海域的等级分布数据;最后,基于掩膜技术与监督分类方法,剔除非核电站温排水影响的温升区,得到研究区海域温排水等级分布(Distribution of Thermal Plume,DTP)特征与统计数据,建立了一套核电站温排水遥感监测方案。实验结果表明,冬季的核电站温排水遥感定量监测结果较好,其他季节受多种因素影响,难以准确定量获取核电站的温排水影响结果。     

Mapping mountain areas: learning from Global,European and Norwegian perspectives

Defining the spatial extent of mountain areas has long been a challenge. In the present century, the availability of digital elevation models(DEMs) incorporated into geographic information systems(GIS) has allowed the definition of mountain areas based on topographic and other criteria. This paper presents the various delineations of mountains that have been prepared at three scales – global, regional(Europe), and national – and explores the reasons and processes leading to these delineations, and how they have been used. A detailed case study is then presented for Norway. Overall, two types of approaches to mapping mountains have been taken: first, considering mountains per se, based on elevation and/or topography; second, considering them among other categories, e.g., landforms or biogeographical, environmental or landscape zones. All attempts to map mountain areas derive essentially from the objectives of those commissioning and/or undertaking the work; a unitary definition remains unlikely.     

新疆和田台阵PSD与PDF分析

和田台阵是我国第一个自主建成并运行至今的小孔径台阵,承担着监测印巴地区核试验以及我国西部地震活动的重要使命.台阵波形数据中充斥着背景噪声,直接影响着数据质量.为了评估台阵噪声水平,本文利用Welch平均周期法对9个子台记录的数十万条噪声样本进行功率谱估计,对出现的谱异常进行了总结归纳,通过绘制概率密度函数图以及单频曲线来研究背景噪声变化范围和规律,最后针对台阵降噪提出了建设性意见.研究结果表明,中心台长周期噪声功率谱密度随季节变化显著,具有周期性;受温度和气压影响,水平分量长周期噪声变化幅度较大,局部频段超出新高噪声模型,建议改善仪器安装条件,或者利用数学方法进行校正.所有子台短周期噪声变化规律与长周期相反,受到采石场影响,谱密度曲线在4~8 Hz之间出现形态规则的高频尖刺,A1、B3、B4子台最为明显,可以通过窄带滤波或者聚束予以压制.本文取得的研究成果为台阵运维提供重要依据,除此之外,总结出的不同地震频谱特征也为地震解释工作提供重要参考.     

Beach recovery from extreme storm activity during the 2013–14 winter along the Atlantic coast of Europe

The storm sequence of the 2013–14 winter left many beaches along the Atlantic coast of Europe in their most eroded state for decades. Understanding how beaches recover from such extreme events is essential for coastal managers, especially in light of potential regional increases in storminess due to climate change. Here we analyse a unique dataset of decadal beach morphological changes along the west coast of Europe to investigate the post-2013–14 winter recovery. We show that the recovery signature is site specific and multi-annual, with one studied beach fully recovered after 2 years, and the others only partially recovered after 4 years. During the recovery phase, winter waves primarily control the timescales of beach recovery, as energetic winter conditions stall the recovery process whereas moderate winter conditions accelerate it. This inter-annual variability is well correlated with climate indices. On exposed beaches, an equilibrium model showed significant skill in reproducing the post-storm recovery and thus can be used to investigate the recovery process in more detail. © 2018 John Wiley & Sons, Ltd.     

基于小波分析的河北省及邻区流动重力场时空动态变化分析

搜集河北省及其邻近地区2010～2014年8期流动重力观测数据和周围绝对重力观测数据,利用小波多尺度分解方法获取河北及邻近区域(110°～120°E,36°～42°N)范围内不同尺度、不同场源深度下的分解结果,并结合该时间段内震例,通过对多期实验结果进行分析,对研究区内的重力变化情况及异常特征有更为清晰的认识,其结论可为河北省及邻近地区后续震情分析、研判提供一定参考。     

基于PPSD方法的广东阳江小孔径井下型地震监测台阵环境地噪声计算与分析

选取2014—2018年广东阳江小孔径井下型地震监测台阵记录的连续波形三分量seed观测数据,使用概率功率谱密度(Probabilistic Power Spectral Densities,以下简称PPSD)方法,对该地震监测台阵所属10个子台进行环境地噪声计算,统计数据月连续率和年连续率;通过PPSD计算获得每小时、每天、每月、每年、5年的环境地噪声结果;汇总结果并分析环境地噪声稳定性和异常性。结果显示:①各子台这5年的环境地噪声水平稳定,说明其井下台基变化和仪器运行稳定,井下观测手段能够避免地面生产生活等人为干扰,解决了因城镇长期建设发展破坏地震监测环境的难题;②存在靠近海边的子台易受台风严重干扰、无线网桥通信方式的子台数据连续率较差、仪器垂直分量相对容易出现运行异常、井下设备故障维修周期较长等问题。     

2016年12月25日智利M7.6地震球型自由振荡检测

智利M7.6的地震激发了地球自由振荡,利用中国数字台网(CDSN)的10个台站记录到7 d的VHZ波形数据,采用功率谱密度估计方法,在没有滤波的情况下,提取了2016年12月25日智利地震激发的地球球型自由振荡基频振型_0S_4～_0S₅₃和一系列的谐频振型,并与PREM模型的理论自由振荡频率峰值进行对比,发现2.5～4.5×10¹³Hz的频率值与PREM模型预测的球型自由振荡周期符合得很好,说明本次地震确实激发了全球范围内的自由振荡,而4.5～6×10¹³ Hz的频率值稍微有偏离,这是由于地壳的横向不均匀所致,可以用来研究地球内部的构造。     

Spatial rules that generate urban patterns: Emergence of the power law in the distribution of axial line length

This paper studies emergence/generation of power law in rank-order distribution of axial line length, which is a global pattern observed in real cities, due to interaction of a set of seven simple spatial rules at a local scale. These rules and their interactions form a model expected to simulate the morphological structure of free spaces in unplanned organic pedestrian small cities. Effects of each of the seven rules are discussed through repeated simulations of eight possible combinations of the rules, using a bottom-up process. The results show that the rules generate environments with statistically stable rank-order distribution of axial line length that follows the power law. It means that the axial maps of the simulated environments have a scale-free hierarchical structure such that their distributions lean toward short axial lines. It also represents dominance of local spatial structure, as the model renders a faster rate of growth at a local scale while allowing a steady growth at a global scale.     

21世纪海上丝绸之路战略构架下中国-肯尼亚海洋合作之探讨

21世纪海上丝绸之路战略是新时期我国重要的对外战略,加强与沿线国家在海上的务实合作是21世纪海上丝绸之路建设的重要内容。文章通过探讨21世纪海上丝绸之路战略对海上合作在合作原则、合作思路及合作重点等方面提出的要求,分析我国21世纪海上丝绸之路建设重要据点——肯尼亚的战略优势及海洋优势,提出中国与肯尼亚海洋合作应从推动双方海洋科研院所之间建立合作机制、建设中肯海洋渔业联合研究中心、资助联合研究项目的开展、加强双方人员交流,扩大青年科学家培训规模、加强双方在海洋非传统安全领域的合作5个方面重点推进的建议,为今后中-肯海洋合作指明方向。     

The changing process and trend of ground temperature around tower foundations of Qinghai-Tibet Power Transmission line

After the construction of Qinghai-Tibet Highway and Railway, the Qinghai-Tibet Power Transmission(QTPT) line is another major permafrost engineering project with new types of engineering structures. The changing process and trend of ground temperature around tower foundations are crucial for the stability of QTPT. We analyzed the change characteristics and tendencies of the ground temperature based on field monitoring data from 2010 to 2014. The results reveal that soil around the tower foundations froze and connected with the artificial permafrost induced during the construction of footings after the first freezing period, and the soil below the original permafrost table kept freezing in subsequent thawing periods. The ground temperature lowered to that of natural fields, fast or slowly for tower foundations with thermosyphons,while for tower foundations without thermosyphons, the increase in ground temperature resulted in higher temperature than that of natural fields. Also, the permafrost temperature and ice content are significant factors that influence the ground temperature around tower foundations. Specifically, the ground temperature around tower foundations in warm and ice-rich permafrost regions decreased slowly, while that in cold and ice poor permafrost regions cooled faster. Moreover, foundations types impacted the ground temperature, which consisted of different technical processes during construction and variant of tower footing structures. The revealed changing process and trend of the ground temperature is beneficial for evaluating the thermal regime evolution around tower foundations in the context of climate change.