抗差估计的多波束测深数据内插方法   总被引：2，自引：0，他引：2  

张志伟  暴景阳  肖付民 《测绘科学》2016,41(10):14-18

针对传统多波束测深数据网格化内插方法抗差性不足的问题,该文将抗差估计理论应用于网格化内插方法中。基于不确定度指标建立了距离不确定度联合加权内插模型,在该模型的权函数中引入了等价权,同时给出了等价权设计方案及迭代初值确定原则,以增强模型的抗差性;介绍了一种节点邻域参考点合理选取方法,给出了改进内插法实现的基本步骤,最后通过实测数据对反距离加权法、联合加权法及改进方法内插水深质量进行比较。结果表明,改进方法内插结果要优于另外两种方法,可应用于多波束测深数据网格化处理中。  相似文献   

Ontogenic variation and effect of collection procedure on leaf biomechanical properties of Mediterranean seagrass Posidonia oceanica (L.) Delile          下载免费PDF全文

Carmen B. de los Santos  Bárbara Vicencio‐Rammsy  Gilles Lepoint  François Remy  Tjeerd J. Bouma  Sylvie Gobert 《Marine Ecology》2016,37(4):750-759

Leaf mechanical traits are important to understand how aquatic plants fracture and deform when subjected to abiotic (currents or waves) or biotic (herbivory attack) mechanical forces. The likely occurrence of variation during leaf ontogeny in these traits may thus have implications for hydrodynamic performance and vulnerability to herbivory damage, and may be associated with changes in morphologic and chemical traits. Seagrasses, marine flowering plants, consist of shoot bundles holding several leaves with different developmental stages, in which outer older leaves protect inner younger leaves. In this study we examined the long‐lived seagrass Posidonia oceanica to determine ontogenic variation in mechanical traits across leaf position within a shoot, representing different developmental stages. Moreover, we investigated whether or not the collection procedure (classical uprooted shoot versus non‐destructive shoot method: cutting the shoot without a portion of rhizome) and time span after collection influence mechanical measurements. Neither collection procedure nor time elapsed within 48 h of collection affected measurements of leaf biomechanical traits when seagrass shoots were kept moist in dark cool conditions. Ontogenic variation in mechanical traits in P. oceanica leaves over intermediate and adult developmental stages was observed: leaves weakened and lost stiffness with aging, while mid‐aged leaves (the longest and thickest ones) were able to withstand higher breaking forces. In addition, younger leaves had higher nitrogen content and lower fiber content than older leaves. The observed patterns may explain fine‐scale within‐shoot ecological processes of leaves at different developmental stages, such as leaf shedding and herbivory consumption in P. oceanica.  相似文献   

不同刚度植物杆群对规则波传播及紊动特性影响研究     

谭超  黄本胜  刘达  邱静  王珍  吉红香 《海洋工程》2016,34(6):38-45

以不同刚度硅胶圆杆群为概化植物模型,测定其抗弯弹性模量,通过波浪水槽实验,研究规则波在不同刚度植物杆群内的流速分布、紊动特征及不同刚度杆群的消浪效果。实验结果表明,当波浪通过柔性杆群时,受其摆动的影响,流速周期变化从单峰型逐渐转变成双峰型,杆群刚度越小形成的二次波峰越明显;不同刚度杆群内水体紊动强度变化显示,杆群刚度越大,造成杆群内水体的紊动强度越大;随着杆群抗弯弹性模量的增大,其消浪系数也增大,消浪系数的增长与材料的抗弯弹性模量值非线性关系,而是在某一弹性模量范围内,对消浪系数的影响较为敏感。  相似文献   

基于人工鱼群算法和SCA等效理论的井中横波速度预测方法     

魏忠宇  刘财  郭智奇  张冰  刘喜武 《世界地质》2018,37(1):282-288

在建立页岩岩石物理模型的基础上,根据等效自相容近似(SCA)岩石物理模型,构建出岩石的纵波速度、横波速度与岩石密度、组分和孔隙度等的定量关系,得出使理论纵波速度和实际纵波速度最接近的孔隙纵横比,进而将该孔隙纵横比作为约束条件来实现横波速度预测。反演算法利用人工鱼群算法来计算最佳孔隙纵横比,并将预测的横波速度与实际测得的横波速度对比,证明了人工鱼群算法的有效性。  相似文献   

1990—2018年长沙市土地利用变化对生态系统服务价值的影响     

彭毅  王远超  高阳 《中国地质调查》2021,8(3):72-80

评估生态系统服务价值(Ecosystem Service Values,ESV)有利于衡量生态系统服务供给潜力和生态效益的大小,对城市生态规划与土地利用管控起到重要的支撑作用。选择长沙市为研究区域,基于1990、2000、2010和2018年4期土地利用现状遥感监测数据集,利用ArcGIS软件和经本地化校正的当量因子法,分析1990—2018年间的土地利用变化特征,并探讨土地利用变化对ESV的影响。结果表明: ①1990—2018年长沙市土地利用变化轨迹以耕地→林地互相转化以及建设用地对耕地、林地的侵占为主; ②1990—2018年长沙市的ESV共减少53.17×10⁸ 元,降幅3.59%,除水域外各类ESV均呈下降趋势,林地和耕地服务价值减少最明显; ③在各单项服务功能中,水文调节的价值最大,其次是气候调节,两者之和占总价值的54%; ④“退耕还林”“退田还湖”“兴工强市”等政策引起的土地利用变化势必对ESV造成影响,城市快速扩张、土地开发会导致ESV不断下降。综合分析认为,在调整研究区土地利用结构、优化土地配置时应充分重视水域、林地等生态系统服务价值较高的土地利用类型,减缓ESV的下降趋势。  相似文献   

EFFECT OF SLAB FLEXIBILITY ON INTERACTION BETWEEN TWO CIRCULAR FOUNDATIONS     

G.&#x;S. LIOU 《地震工程与结构动力学》1996,25(6):561-583

The paper is aimed at investigating the effect of foundation rigidity on dynamic stiffness for two circular foundations on a viscoelastic medium. To generate the dynamic stiffness, a substructure technique is employed. For the substructure of a viscoelastic medium, the solution for wave motion reported in Reference 11 is used. For the substructures of two flexible foundations, classical plate theory with the inertial force neglected is employed to find the displacement fields of the foundation plates subjected to the interaction stresses. Then, the continuity condition for all the substructures is imposed implicitly by using the variational principle; then with the help of the reciprocal theorem the dynamic stiffness for the two flexible foundations can be obtained. For the numerical study, the boundary condition at the rims of both foundation plates is assumed to be a hinge connection to superstructures. Some numerical investigations are performed and the effect of foundation rigidity on dynamic stiffness is examined. Some discussions and conclusions are also made.  相似文献   

SEQUENTIAL STIFFNESS DESIGN FOR SEISMIC DRIFT RANGES OF A SHEAR BUILDING–PILE–SOIL SYSTEM     

T. NAKAMURA  I. TAKEWAKI  Y. ASAOKA 《地震工程与结构动力学》1996,25(12):1405-1420

A shear building supported by a prescribed pile–soil system is subjected to bedrock earthquake input. A new design procedure is presented for generating a sequence of stiffness designs satisfying the constraints on interstorey drifts. The mean peak interstorey drifts of the shear building subjected to a set of spectrum-compatible ground motions at the bedrock are evaluated by a modal combination rule. Tuning of the fundamental natural period of a shear building with a fixed base with that of a shear beam ground results in a non-monotonic sequence of stiffness designs with respect to a ground stiffness parameter and previous approaches cannot be applied to such a problem. This difficulty in finding such a non-monotonic sequence is overcome by utilizing the ground stiffness parameter and the superstructure stiffness parameter alternately in multiple design phases and by developing a new multi-phase perturbation technique. Fundamental characteristics of this sequence of stiffness designs and the effect of ground stiffnesses on the design of the shear building are disclosed. It is further shown that the stiffness contour method is also useful for the design procedure such that a scattering effect in the estimates of ground stiffnesses is taken into account. The usefulness of the proposed procedure of sequential stiffness design and contour line method is demonstrated through several sequential design examples.  相似文献   

改进的等效半空间法及瑞雷波频散曲线反演   总被引：9，自引：4，他引：5       下载免费PDF全文

陈祥  孙进忠 《地球物理学报》2006,49(2):569-576

层状模型的理论频散曲线表明,层状模型表面瑞雷波同一频率对应的相速度具有多值特点,这就是所谓的瑞雷波多阶性. 面波的多阶性导致了实测频散曲线的复杂性,当地层中存在软弱夹层时这一问题尤为突出,从而给实测频散曲线的解释带来了困难. 本文从工程实用的角度出发,根据等效半空间理论,提出了一种计算理论频散曲线的新算法——改进的等效半空间法,避开了面波多阶性这一复杂问题. 由此方法计算得到的面波相速度并不同于某个具体阶数的面波,而是对多阶面波的综合反映. 按照改进的等效半空间法编制了拟合反演程序,并在工程中进行了运用,取得较好的效果.  相似文献   

基于随机振动理论确定桥梁地震碰撞的临界间隙   总被引：3，自引：1，他引：2  

李忠献  岳福青  周莉  刘旭锴 《地震工程与工程振动》2006,26(4):156-161

确定梁桥邻跨间避免地震碰撞的最小间隙,对于梁桥地震碰撞危险性预测及防地震碰撞措施的设计有着显著意义。本文基于随机振动理论建立梁桥地震碰撞邻跨临界间隙的计算方法,分析模型采用跨径不等的两跨简支梁桥,且考虑隔震支座非线性恢复力的影响。文中首先建立了系统的非线性运动方程;随后运用随机等效线性化理论将其线性化;最后在复模态空间推导了临界碰撞间隙的均值与方差的计算方法。人工地震动的非线性时程分析结果验证了本文算法的正确性。参数分析表明,临界间隙随邻跨长度比增大而增大,随支座屈服力与上部结构重量比值减小而增大,随隔震支座屈服位移增大而增大,随桥墩振动周期增大而增大。隔震支座屈服前后刚度比值对临界间隙大小影响很小。  相似文献   

浏阳河流域生态补偿标准额度动态估算     

王明宽  舒清海  莫宏伟  刘娣 《地理空间信息》2021,19(1):125-127,130

生态补偿标准是生态补偿研究发展的关键问题,特别是以定量的方式量化补偿金额.以浏阳河流域为研究区,提出了基于单位面积价值当量因子的生态服务功能价值评估法.该方法利用GIS技术对研究区生态服务功能价值进行动态评估,并将皮尔生长曲线模型和表征社会经济发展水平的恩格尔系数相结合计算生态补偿系数,最终构建得到单位面积生态补偿标准...  相似文献