基于非静压模型类海啸波作用下海堤越浪特性

【目的】研究海啸波在斜坡海堤上越浪的水动力特性。【方法】基于非静压模型NHWAVE建立高精度二维数值波浪水槽,通过对日本2011年实测真实海啸进行参数化形成类海啸波形,并设置系列计算工况,深入分析入射波高、水深、岸滩坡度及海堤坡度对类海啸波作用下海堤越浪特性的影响,并将计算结果与孤立波进行对比。【结果与结论】相同工况下,类海啸波的单宽越浪量大于孤立波,波浪经海堤消能后,能量衰减,孤立波能量损耗率大于类海啸波;随波高和水深增加,越浪量均增大;海堤坡度对越浪量的影响不大;岸滩坡度减缓,波浪速度将在堤前聚集,类海啸波在1∶20的岸滩坡度下越浪量达到最大。研究结果可为近岸水利防护工程的建设提供参考。     

基于DEM的5节点二阶差分坡度算法模型与实验分析

 坡度作为最基本的地形因子,是构建地学分析模型的基础数据,基于格网DEM的坡度计算模型的精度分析一直是地学分析的重要研究内容。本文通过分析计算坡度的 差分模型误差来源及特征,提出了一种新的模型——5节点二阶差分模型。其基本思想是顾及多距离邻近点高程信息,采用5×5分析窗口,建立单倍格网和两倍格网的差分计算线性组合模型。并通过数学分析的理论推导证明该模型可以显著提高计算精度。实验选取典型数学曲面并对其采用不同的分辨率(1m和5m)进行离散化精度验证。计算结果表明,与现有的差分模型相比,5节点二阶差分模型可以显著提高坡度的精度,对应于两种分辨率的DEM,该模型计算坡度的精度可以分别提高7×10⁴倍、3×10³倍以上,表明该模型对于高分辨率DEM数据更为适用。本研究不仅丰富了数字地形分析的方法体系,为相关地学模型分析提供更精确的坡度数据,而且为将来改进地形曲率因子等计算模型提供了一定的参 考和借鉴。     

水流算法对于坡度坡长因子的影响研究

坡度坡长因子是影响土壤侵蚀的主要地形因子。单流向算法和多流向算法得到的坡度坡长因子差异非常大。基于多流向算法的坡长计算得到的坡度坡长因子图,光滑连续,符合坡面漫流原理,比单流向算法得到得坡长计算得到的坡度坡长因子更加合理。     

地形坡度对越野机动时间影响分析

为研究地形坡度对车辆越野机动时间的影响,预测和估计车辆通行时间,采用了数字高程模型(Digital Elevation Model,DEM)来模拟复杂的地貌形态。采用了移动窗口法计算了DEM格网单元的坡度,建立数学模型研究了地貌对车辆越野机动的速度影响系数,包括两方面:坡度引起路线延长和坡度影响车辆自身速度。通过实例分析计算了车辆通行时间,该方法为准确研究车辆越野机动通行时间提供了理论依据和参考。     

基于地面LIDAR无组织数据表面重建的实现

一、Delaunay算法的基本原理 1．Voronoi图的定义 Voronoi图,又叫泰森多边形或Dirichlet图,它是由一组由连接两邻点直线的垂直平分线组成的连续多边形组成。N个在平面上有区别的点,按照最邻近原则划分平面;每个点与它的最近邻区域相关联。     

基于地面LIDAR无组织数据表面重建的实现

一、Delaunay算法的基本原理 1．Voronoi图的定义 Voronoi图,又叫泰森多边形或Dirichlet图,它是由一组由连接两邻点直线的垂直平分线组成的连续多边形组成。N个在平面上有区别的点,按照最邻近原则划分平面;每个点与它的最近邻区域相关联。     

基于当量距离算法的山洪灾害避灾路线研究

山区乡村防灾减灾能力薄弱,山洪灾害突发性强,避灾响应时间短,容易造成人员伤亡,合理设计避灾路线,有助于降低灾害损失。本文基于GIS技术,以河北省邢台市田白芷村所在山区避灾路线规划为例,通过高分辨率无人机摄影测量获得研究区DEM数字高程模型和正射影像。以坡度作为避灾阻力值,利用成本距离和成本路径函数计算山区初始避灾路线,以山洪沟所在区域、坡度较大区域作为避灾路线阻隔,同时充分考虑现有山路,优化形成最终避灾路线,基于避灾路线的距离和平均坡度2个指标将研究得到的避灾路线与原有的避灾路线进行定量对比分析。研究结果表明：① 在设计形成的20条远距离避灾路线中,该方法能够缩短18条避灾路线的长度,同时有10条线路的平均坡度得到降低,其余8条线路平均坡度的增加控制在2°以内;② 生成的路线较原始路线单条最长可缩短329.74 m,且平均坡度仅增加0.68°,实现增加少量的平均坡度来缩短避灾距离,从而提高避灾效率;③ 剩余2条路线分别增加了15.21 m和9.57 m行程使得平均坡度降低了8.43°和1.43°,实现增加少量的距离来降低线路的平均坡度,从而提高避灾的安全性;④ 田白芷村南部临近避灾点,避灾难度较低,而田白芷村北部到达避灾点的行程较长,最远长达1210.02 m,避灾难度较大。优化后的避灾路径与大坡度阻隔区域分离,与山洪沟的贴合度也大大降低,可为相关决策人员提供科学依据。     

基于边界替代的人口数据空间化方法研究

首先将山东省各县市按级别分类,利用回归方法得到不同级别县市的城镇居住密度与农村居住密度,然后根据乡镇驻地位置,构造Voronoi图来替代乡镇边界。在此基础上利用各乡镇人口数据与居民点数据计算得到各 Voronoi图形的居住密度,并将该密度赋予每个图形的发生点(即乡镇驻地位置),而后利用反距离插值算法,并结合窗口移动平均处理,得到全省的居住密度分布图。使用居住密度分布图和居民点分布数据,计算人口分布数据。并根据每个县市的图上汇总人口和统计人口,计算得到各县市的调整系数,使用该系数对每个栅格的人口数进行调整,保证了各县市总人口不会出现误差。最终得到山东省1km×1km栅格的人口分布数据。最后选取某些样本县, 在样本县内对比每个乡镇图上的人口与实际统计人口,结果表明该人口分布数据有较高的精度。     

平行剖面法用棱柱和截锥公式计算块段体积注意的问题

用平行剖面法计算资源/储量时,若矿体块段在相邻两剖面上均有面积,且控制两面积的工程间距或控制每个剖面面积的工程见矿平均厚度不相等的情况下,使用棱柱体公式计算块段体积,或相邻两剖面上面积形状不相似的情况下,使用截锥体公式计算块段体积,均存在一定的误差。而拟柱体公式则是精确计算块段体积的通用公式,其使用不受上述条件的限制。因此,在这种情况下,建议限制或停止使用棱柱体和截锥体公式,提倡统一使用拟柱体公式来计算矿体块段的体积。     

虚拟站点在黑河流域降水模拟中的应用

降水作为气候系统的关键因素,也是影响区域植被生长以及生态变化规律的重要因子。本文针对黑河流域气象站点分布稀疏情况,采用信息熵及半变异函数理论构建该流域虚拟气象站点,并结合部分已有站点对整个流域降水进行插值模拟。信息熵可以计算每个站点降水值所包含的信息,通过联合熵以及条件熵来依次选取所含信息量多的站点,同时结合半变异函数模型来观察各站点之间的空间相关性,以此构建最优站点数据集。利用1991-2003年该流域15个气象台站的年平均降水量作为基础数据,考虑高程、坡度、坡向对降水的影响,对降水进行相关性分析,建立回归方程反演虚拟站点降水值。最后,采用协同克里金（Co-Kriging）与具有漂移的克里金（KED）方法对该流域进行插值,对比插值精度。结果表明,增加虚拟站点有效提高了降水插值精度,在该情况下使用KED方法插值结果与观测值最接近。     

Preliminary study on plasma membrane fluidity of Psychrophilic Yeast Rhodotorula sp.NJ298 in low temperature

The ability of cell to modulate the fluidity of plasma membrane was crucial to the survival of microorganism at low temperature. Plasma membrane proteins, fatty acids and carotenoids profiles of Antarctic psychrophilc yeast Rhodotorula sp. NJ298 were investigated at -3 ℃, 0 ℃ and 8 ℃. The results showed that plasma membrane protein content was greater at -3 ℃ than that at 8 ℃, and a unique membrane polypeptide composition with an apparent molecular mass of 94.7 kDa was newly synthesized with SDS-PAGE analysis; GC analysis showed that the main changes of fatty acids were the percentage of unsaturated fatty acids (C18∶ 1 and C18∶ 2) and shorter chain saturated fatty acid (C10∶ 0) increased along with the decrease of the culture temperature from 8 ℃ to -3 ℃; HPLC analysis indicated that astaxanthin was the major functional carotenoids of the plasma membrane, percentage of which increased from 54.6±1.5% at 8 ℃ to 81.9±2.1% at -3 ℃. However the fluidity of plasma membrane which was determined by measuring fluorescence anisotropy was similar at -3 ℃, 0 ℃ and 8 ℃. Hence these changes in plasma membrane's characteristics were involved in the cellular cold-adaptation by which NJ298 could maintain normal plasma membrane fluidity at near-freezing temperature.     

Information for authors

正1 Aims and Scope Advances in Polar Science(APS)is an international,peer-reviewed journal jointly sponsored by the Polar Research Institute of China and the Chinese Arctic and Antarctic Administration.APS is a comprehensive academic journal dedicated to presentation of multi-disciplinary achievements in Arctic and Antarctic expeditions and research.Its primary purpose     

JOURNAL OF OCEAN UNIVERSITY OF CHINA

<正>Copyright Submfnion of a roanusatpt inks:that the work described has not been published before(exoept In the form of an abstrW or as part of a published lecture,review,or thesis);that it is not under consideration for publication elsewhere that its publication has been approved by ail     

Information for Authors

<正>The Journal of Ocean University of China(Oceanic and Coastal Sea Research)is a comprehensive academic quarterly sponsored by the Ocean University of China,published one volume per year.This journal is devoted to the publication of the theoretical and applied research results on oceanography and marine fisheries.The fieldcovered include the physical,chemical,biological,geo-     

Hydraulics and Hydrology in Mountain Areas

<正>The 35th IAHR World Congress was held in Chengdu,China from September 8 to September 132013.The title of the conference was:"The Wise Finds Pleasure in Water:Meandering through Water Science and Engineering".During the congress,1239 papers were presented in 139sessions for oral presentations and 7 sessions for poster presentations.After the Congress,a Committee was appointed to select some of the best papers presented at the Congress for publication,after a     

Sea ice thickness measurement in spring season in Bothnian Bay using an electromagnetic induction instrument

As an important component of the cryosphere,sea ice is very sensitive to the climate change.The study of the sea ice physics needs accurate sea ice thickness.This paper presents an electromagnetic-induction(EM) technique which can be used to measure the sea ice thickness distribution efficiently,and the successful application in Bothnian Bay.Based on the electromagnetic field theory and the electrical properties of sea ice and seawater,EM technique can detect the distance between the instrument and the ice/water interface accurately,than the sea ice thickness is obtained.Contrastive analysis of the apparent conductivity data obtained by EM and the value of drill-hole at same positions allows a construction of a transformable formula of the apparent conductivity to sea ice thickness.The verification of the sea ice thickness calculated by this formula indicates that EM technique is able to get reliable sea ice thickness with average relative error of only 12%.The statistic of all ice thickness profiles shows that the level ice distribution in Bothnian Bay was 0.4-0.6 m.     

Thermohaline structure inhomogeneity associated with polynia at the northern margin of Emery Ice-shelf

Based on the hydrographic data in austral summer during the 22nd Antarctic Expedition of China(2005/2006),some features can be found about the northern margin of Emery ice shelf as follows.The heat content in the surface layer(0-50 m) at the eastern end and the western end of the ice-shelf margin is much higher than that at the middle.The upper mixing-layer depth and the seasonal thermocline depth at the middle of the ice-shelf northern margin are much shallower than those at the both ends.However there is much less difference between the middle and the ends in the bottom layer.The remote sensing photos show that the inhomogeneity in the surface-layer water is closely related to the spatial distribution of the floes and polynia in the area.     

Phylogenetic analysis of cultivable bacteria isolated from Arctic sea-ice

Phylogenetic analysis based on 16S rDNA of 8 strains of cultivable bacteria isolated from Arctic sea-ice was studied.The results showed that strain BJ1 belonged to genus Planococcus,which was a genus of low mole percent G C gram-positive bacteria;strain BJ6 belonged to genus Burkholderia of β-proteobacteria and the rest 6 strain all belonged to γ-proteobacteria,of which strain BJ8 was a species of Pseudoalteromonas,strain BJ2-BJ5 and BJ7 were members of genus Psychrobacter.Phylogenetic analysis also indicated that bacteria of genus Psychrobacter of the isolates formed a relatively independent phylogenetic cluster in comparison with other bacteria belonged to genus Psychrobacter.     

Information for authors

正1 Aims and Scope Advances in Polar Science(APS)is an international,peer-reviewed journal jointly sponsored by the Polar Research Institute of China and the Chinese Arctic and Antarctic Administration.APS is a comprchensive academic journal dedicated to presentation of multi-disciplinary achievements in Arctic and Antarctic expeditions and research.Its primary purpose is to publish achievements in fundamental research,applied