Shaking Table Tests on Bridge Foundation Reinforced by Anti-slide Piles on Slope

Based on the requirement of seismic reinforcement of bridge foundation on slope in the Chengdu-Lanzhou railway project, a shaking table model test of anti-slide pile protecting bridge foundation in landslide section is designed and completed. By applying Wenchuan seismic waves with different acceleration peaks, the stress and deformation characteristics of bridge pile foundation and anti-slide pile are analyzed, and the failure mode is discussed. Results show that the dynamic response of bridge pile and anti-slide pile are affected by the peak value of seismic acceleration of earthquake, with which the stress and deformation of the structure increase. The maximum dynamic earth pressure and the moment of anti-slide piles are located near the sliding surface, while that of bridge piles are located at the top of the pile. Based on the dynamic response of structure, local reinforcement needs to be carried out to meet the requirement of the seismic design. The PGA amplification factor of the surface is greater than the inside, and it decreases with the increase of the input seismic acceleration peak. When the slope failure occurs, the tension cracks are mainly produced in the shallow sliding zone and the coarse particles at the foot of the slope are accumulated.     

Genetic Diversity of Toona ciliata Populations based on SSR Markers

In order to provide a theoretical basis for the protection and development of T. ciliata germplasm resources, we studied the genetic diversity of T. ciliata by using SSR (Simple Sequence Repeat) primers to evaluate the genetic diversity of 192 T. ciliata germplasm samples from 24 populations of 5 provinces. DataFormater, Popgene, NTSYS, TFPGA and other software were used for genetic data conversion, genetic parameter estimation, dendrogram construction and genetic variation analysis. The results showed that: 1) a total of 17 alleles (N_a) were detected in seven pairs of primers, with an average of 2.260 for each primer. Among them, the highest numbers of alleles (4) were detected in primers S11 and S422.The mean value of Nei’s genetic diversity index (H) was 0.4909, the mean value of Shannon information index (I) was 0.7321, and the mean value of polymorphic information content (PIC) was 0.5182. The mean expected heterozygosity (H_e) and observed heterozygosity (H_o) were 0.1055 and 0.4956, respectively. The Nei°s genetic distances of the populations ranged between 0.0002 and 2.6346, and the mean was 0.5477. The average genetic diversity level (H=0.1044) of the 24 populations was lower than that of the species (H=0.4909). 2) The genetic differentiation coefficients (F_st) varied from 0.2374 to 0.9148, with an average value of 0.7727. The mean of population gene flow (N_m) was 0.0735, indicating a low level of genetic exchange between populations, and suggesting that the genetic variation mainly came from within populations. 3) With the UPGMA method, the 24 populations were clustered into 3 groups at Nei’s genetic identity (0.99): the populations from Guizhou Province and Guangxi Zhuang Autonomous Region were clustered into one group, the populations from Hunan Province were in another group, and the populations from Hubei Province were in the third group. The Mantel test analysis showed a significant correlation between Nei’s genetic distance and geographic distance (r=0.6318, P=0.009?0.05). The genetic diversity of the 24 populations of T. ciliata was at a low level. Geographic isolation was the main reason for genetic differentiation among T. ciliata provenances. In the protection of germplasm resources of T. ciliata, emphasis should be placed on breeding genetic resources from the populations with higher genetic diversity (P14, for example). As for the populations with low genetic diversity, an ex-situ protection strategy as well as ecological and timber objectives, should be taken into account to maximize the conservation and utilization of the diversity of T. ciliata.     

融合式研究趋势下的地理信息教学体系探索

城市研究的范式在大数据和人工智能的影响下已经发生了巨大变化。本文根据城市研究及地理信息科学的发展历程和学科脉络,提出城市空间信息学是社会和产业需求导向的一个新兴知识领域,也是融合式研究趋势下地理信息教学和研究的一个发展方向。城市规划和地理信息科学两大类专业虽然具备孵化出城市空间信息学人才的学科基础,但是其学科体系都需要较大的改变才能实现突破;从现有的学科设置的体系看,地理空间信息工程专业由于提供了同时培养学生系统思维、空间思维和计算思维的框架,具备发展城市空间信息学本科教育的入口。本文在此基础上提出了城市空间信息工程本科专业的培养方案设计思路,期望能够对城市空间信息学的学科发展以及教学研究带来讨论契机,并推动地理信息学科和城市规划学科的可持续发展。     

基于OCO-2卫星观测模拟高精度XCO2的空间分布

本文首次基于OCO-2卫星观测数据,采用高精度曲面建模（High Accuracy Surface Modeling, HASM）的方法来模拟大范围高精度的二氧化碳柱浓度（XCO₂）的空间分布。首先,探讨分析HASM方法应用于模拟OCO-2卫星观测XCO₂的空间分布的可行性。从2014年9月至2015年8月OCO-2观测的12个月的XCO₂数据中,分别随机选取其各个月90%的XCO₂数据用于空间插值,剩余10%作为精度验证点。自验证结果表明,12个月的平均绝对值误差为0.34 ppm。由此可见,HASM适用于模拟OCO-2卫星观测XCO₂的空间分布。然后,采用HASM对OCO-2在2014年9月至2015年8月的各个月观测数据进行空间插值,获取空间分辨率为0.5°×0.5°的各个月均值XCO₂的空间分布,同时基于地基观测TCCON( Total Carbon Column Observing Network)站的XCO₂数据对HASM模拟结果进行交叉验证。验证结果表明,HASM模拟的XCO₂与TCCON站对应观测数据相比,其平均绝对值误差为0.81 ppm,相关系数为0.88。因此,HASM在模拟OCO-2卫星观测的XCO₂空间分布上具有很大的优势。     

基于GLM-PSO-coKriging模型的地表形变研究

以斜坡灾害易发地带兰州市城关区为研究区,通过PS-InSAR技术提取地表形变点的地表形变速率,反映地质灾害在空间范围内的分布。以协克里金插值为基础,结合广义线性模型（GLM）和粒子群优化算法（PSO）,构建PSO-GLM-coKriging插值模型,以地表形变速率为主变量,DEM,岩土疏松度和NDVI拟合参数为协变量,进行空间插值模拟。与co-Kriging模型和GLM-co-Kriging模型相比较,PSO-GLM-coKriging插值模型具有更高的精度和更好的模拟效果,消除了多维度产生的复杂度,改善了小尺度范围内的插值效果,3个模型的误差分别为1.25 mm/year,0.70 mm/year,0.47 mm/year。因此,通过PSO-GLM插值模型对形变点空白区的插值模拟,对城关区城镇化的规划建设提供一定的数据和理论支撑。     

海水入侵的同位素研究

本文用同位素方法研究了我国莱州湾海水入侵的成因及变化发展趋势。结果表明，在莱州湾西部的广饶地区属于卤水（古海水）入侵区，在莱州湾东部的龙口地区属于现代海水入侵区。 而在莱州地区则既存在着海水入侵又存在着卤水入侵。     

地表质量负载对格陵兰岛区域GPS站点坐标时序特征的影响

选取ITRF2008框架下格陵兰岛区域12个GPS站2013年1月-2016年12月期间的日解坐标时间序列作为研究对象,并利用极大似然估计分析地表质量负载改正前后各站点的噪声特性、速度场及周期项振幅。结果表明：站点最优噪声模型主要为白噪声+幂律噪声与白噪声+闪烁噪声,地表质量负载形变修正GPS坐标时序后,明显增加U方向闪烁噪声的成分,平均降低其速度约0.36 mm/a,对水平方向影响较小;同时分别降低高程方向44.1%、14.2%的1 a项、0.5 a项振幅,相反,却增加了水平方向的周期项振幅。     

多源数据的嫦娥四号着陆点定位

嫦娥四号着陆点的精确定位对于工程任务安全高效实施至关重要。本文基于嫦娥二号正射影像、LROC NAC正射影像、嫦娥四号降落相机影像、嫦娥四号监视相机影像等多源数据,利用影像特征匹配定位和单像视觉测量定位技术,确定了嫦娥四号着陆点的精确位置为(177.588°E,45.457°S)。本研究结果对综合利用多源数据深入开展着陆区科学研究具有重要意义。     

软刚臂上铰节点疲劳失效分析和现场监测方案设计

海洋环境荷载非平稳性、时变性等特点为海洋工程结构设计带来挑战。海洋工程结构设计的不准确性可导致其真实服役时间低于自身设计寿命。针对塔架软刚臂系泊系统上铰节点服役过程中出现的疲劳磨损问题,发展出一种基于原型监测技术的铰节点疲劳寿命实时预估方法。通过开展有限元模拟,建立系泊腿在指定摆动角度下摩擦系数和热点区域应力分布的对应关系,提出了软刚臂上铰节点的原型监测方案。结合不同摩擦系数对铰节点接触面损伤行为的影响,提出了软刚臂主铰结构疲劳寿命计算评估方法,能够实现铰节点疲劳的完整性分析。     

大菱鲆三倍体人工诱导条件优化及规模化诱导

大菱鲆(Scophthalmus maximus)是我国重要的海水养殖鱼种,三倍体诱导对其种质改良、产业提升和生态安全具有重要的价值。目前有关大菱鲆三倍体的人工诱导虽已有报道,但对其诱导条件缺乏细致的研究。本文采用冷休克法抑制第二极体排放,通过对诱导处理起始时刻、温度和持续时间3个主要因素的单因子实验,筛选其最佳诱导条件。结果显示,在受精和孵化水温为15.0±0.5℃条件下,受精后6 min,用–2～–1℃处理25 min可获得较好的诱导效果,流式细胞仪检测其诱导率可达100%。随后在最适条件下进行了规模化诱导,获得鱼苗200万尾以上,其诱导率高于98%。跟踪观察发现,三倍体诱导组胚胎的形态及孵化时间与二倍体对照组基本一致。本研究结果可为大菱鲆三倍体的产业化应用提供基础。