基于气象监测网络的森林火险快速预警模型

森林火灾发生频繁且突发性强,进行森林火险快速预警对于减小森林火灾损失和促进森林资源可持续发展至关重要。本文基于GIS空间分析和可视化技术,利用地面气象站构建实时气象监测网络,设计了运用气象监测网络的森林火险预警模型,可实现森林火险及时、快速预警。模型应用层次分析法建立了预警因子重要性层次结构并确定预警因子的权重;运用Voronoi图技术,基于气象站点和实时气象数据,构建气象监测网络;利用叠置分析技术计算得出预警结果。基于该模型设计的森林火灾快速预警系统应用于青海省林业局,验证了系统可行性与适用性,该模型可全面、准确、快速地实现对森林火险的预警。结果表明：① 根据预警模型及实时气象监测数据,可及时发出预警信号,快速实现县级、林场级别的森林火险早期预警和及时响应;② 运用GIS可视化技术,可快速生成相关区域森林火险的空间分布专题图,直观地观察预警等级的变化情况。实践表明,森林火险快速预警对森林火灾进行有效预防、中断管理和制定扑救措施具有重要的指导作用,并对森林防火工作、保护森林资源和人类生命财产安全具有重大意义。     

利用近震及远震转换波测定永清M4.3级地震的震源深度

根据近震沉积层基底界面转换波Sp震相和远震深度震相sP、pP的特征,对2018-02-12永清M4.3地震的震源深度进行分析,运用F-K波数与频率方法拟合近震理论波形、Teleseis方法拟合远震理论波形,并与实际波形对比,对震源深度进行测试。结果表明,永清地震的震源深度为16~17 km,从发震位置和震源深度分析来看,此次地震发生在中上地壳,与区域内其他地震事件类似。     

甘肃南部武都地区泥石流危险性评价

泥石流的发生受控于多种因子,而各因子属性段对泥石流的发生起到不同的作用.以甘肃南部武都地区为研究区,考虑到地震扰动影响并结合当地的地质环境条件,选取了高程、坡度、岩性、土地利用类型、滑坡点密度、地震因子、地质构造缓冲区及归一化植被指数(NDVI)等8个评价因子进行危险性评价.而后基于信息量模型和敏感性分析法对各影响因子属性类进行计算分析,得到各属性类的量化值.最后通过叠置分析,得到泥石流灾害危险性分区.结果表明,在中度、高度及极高度危险区内,信息量模型中分布的泥石流面积占研究区泥石流总面积的百分比为22.5％,24.7％,37.2％,而敏感性模型中占到的比例分别为25.5％,28.1％和36.4％.敏感性模型中中度危险区以上包含的泥石流比例占到90％,大于信息量模型的84.4％,因此,采用敏感性模型得到的危险性分区结果具有更高的精确性,能够为实际应用提供参考依据.     

运用特征点的矢量空间数据盲水印算法

针对矢量空间数据水印攻击的特点,该文提出了基于特征点的矢量空间数据盲水印算法。在水印嵌入前,应用道格拉斯-普克方法,提取矢量数据特征点;对特征点进行离散傅里叶变换,将水印通过量化的方法嵌入离散傅里叶变换后的幅度系数和相位系数中;水印被多次嵌入,实现了水印的盲提取。试验结果表明,该方法引起的空间数据误差很小,同时对旋转、平移、要素排序、数据格式转换、裁剪、压缩、增删点等攻击具有较好的鲁棒性。     

Changes in Frequency of Electromagnetic Radiation from Loaded Coal Rock

To understand the relationship between the frequency of electromagnetic radiation (EMR) emitted from loaded coal rock and the micro-crack structures inside it, and assess the stress state and the stability of coal rock by analyzing frequency changes in characteristics of its emitted EMR, we first experimentally studied the changes in time sequence and the frequency spectrum characteristics of EMR during uniaxial compression, then theoretically derived the relationship between the principal frequency of EMR signals and the mechanical parameters of coal crack and analyzed the major factors causing the changes in the principal frequency, and lastly verified the results at Nuodong Coal Mine, Guizhou Province, China. The experimental results showed that (1) EMR intensity increased with the applied stress on loaded coal rock during its deformation and failure and could qualitatively reflect the coal’s stress status; (2) with the applied stress increasing, the principal frequency gradually increased from near zero to about 60 kHz and then dropped to less than 20 kHz. During this period, coal rock first stepped into the linearly and elastically deformed stage and then ruptured around the peak load. Theoretical analysis showed that there was a negative correlation between the principle frequency and the size of internal cracks. Field detection showed that a lower principle frequency was generated from coal rock applied by a greater load, while a higher principal frequency was generated from coal rocks suffering a weaker load.     

中国黄海海域的构造演化

燕山运动以来,华北东部地区发生了翻天覆地之构造转变,构造体制从印支期末的华北地块与扬子地块的拼贴－增生,转变为地幔热柱演化－区域伸展断陷,地形地貌上亦从东部的高原转变为华北东部盆－山耦合格局。     

The relationship between fat content and biological parameters of bigeye tuna (<Emphasis Type="Italic">Thunnus obseus</Emphasis>) in the Western Central Indian Ocean

Comparing fat content with physiological status can throw light on the reproduction and feeding behavior of the fish. The biological data of 586 bigeye tuna were collected from the longline fishery in the waters of Western Central Indian Ocean from November, 2012 to March, 2013. The spatial or temporal distribution of the fat content, and the relationships of fat content with gender, round weight, gonadal maturity and fork length were analyzed. A generalized additive model (GAM) was used to analyze the relationships between fat content and fork length (FL), gonadosomatic index (GSI), condition factor (K), and somatic index (SI). Results showed that: 1) the fat content of bigeye tuna was in the range of 3.1%–27.1% with the average 12.8%; 2) there were no significant geographical differences of average fat content (P > 0.05) among 1° squares in general; 3) there were no significant differences (P > 0.05) of the fat content for different genders, months, or gonad maturity stages; 4) there was an extremely significant correlation (P = 0.000) between fat content and FL and GSI. There was no significant correlation (P = 0.051) between fat content and K. There was a significant correlation (P = 0.003) between fat content and SI. The results of this study suggest that the fat content of the matured fish was relatively stable. The survey area was in a spawning region, and the survey period was the spawning season for bigeye tuna.     

遥感技术在断裂研究中的应用——以张家口—蓬莱断裂带为例

张家口一蓬莱断裂带是一条北西西向活动断裂带。本文选取ETM+光学影像和SRTM高程影像作为主要数据源,结合研究区已有地质资料研究发现该带断裂构造的北西西向线性特征明显。从水系分布和错断地形等地貌标志判断,该断裂具有左阶组合样式和左行走滑活动特征。据遥感影像综合特征,可将该带分为张家口段、延庆-怀来段和北京一天津段,影像特征分段性显著,并与断裂带的分段性一致。研究结果表明,张家口-蓬莱断裂具有左行走滑的运动学特征,限制或错断北北东或北东向断裂,并且控制该区域的左阶雁列式第四纪盆地群和第四纪冲洪积物的分布。该断裂带各段对不同规模的水系分布和形态影响比较大,且北京-天津地区的华北平原段断裂对第四纪冲洪积扇和沿海地区的贝壳堤的形态和分布有一定的控制作用。地球物理深部数据和野外地质考察资料也证实了遥感解泽的结果,证明遥感技术在探查断裂构造空间展布和活动性鉴定中有着广泛的应用前景。     

移动激光扫描技术下的隧道横断面提取及变形分析

移动激光扫描技术具有获取数据速度快、点密度大、精度高、无需拼站等优点,本文利用该技术获取的点云数据对隧道形变检测方法进行了研究和应用。首先,结合边界检测算法和随机抽样一致性算法计算隧道的空间中轴线,在此过程中省去了传统方法中对大量点云进行旋转的过程。其次,采用k近邻法计算各断面的缓冲区对点云进行分块,并利用投影法构建断面点集,提高了断面点集获取的速度。最后,提出了一种迭代椭圆拟合去噪的方法,在拟合出断面线的同时去除了噪声。最终通过与全站仪获取的断面数据进行对比验证了该方法的精度并将其应用在某段圆形盾构隧道上,采用隧道检测小车获取点云数据,每隔2 m截取一个断面,然后通过与理论断面的对比分析了隧道的形变情况。