CUBE算法及其在多波束数据处理中的应用   总被引：5，自引：0，他引：5  

王德刚  叶银灿 《海洋学研究》2008,26(2):82-88

阐述了一种基于表面生成的多波束数据处理方法——CUBE(Combined Uncertainty and Bathymetry Estimator)算法,用该方法可以对观测区域网格节点"真实"水深及相关误差进行估计。与从测量水深中选择出"最佳"数据的手工交互方式的多波束数据编辑手段不同,CUBE算法具有很强的抗差性和较高的效率,适合于实时多波束数据处理。对南海某测区多波束数据处理结果表明,在没有人工干预的情况下,利用CUBE算法去噪生成的海底DTM图与手工编辑生成的相当吻合。CUBE算法和手工编辑方法综合对比得出,CUBE算法能够很好地保留水深地形细节,在计算效率、误差评估、实时处理等方面比手工编辑方法具有较大的优势。  相似文献   

Application of Active Contour Model in Tracking Sequential Nearshore Waves     

Yu-Hung HSIAO  Min-Chih HUANG 《中国海洋工程》2009,23(2):251-266

In the present study,a generalized active contour model of gradient vector flow is combined with the video techniques of Argus system to delineate and track sequential nearshore wave crest profdes in the shoaling process,up to their breaking on the shorehne.Previous applications of active contour models to water wave problems are limited to controllable wave tank experiments.By contrast,our application in this study is in a nearshore field environment where oblique images obtained under natural and varying condition of ambient light are employed.Existing Argus techniques produce plane image data or time series data from a selected small subset of discrete pixels.By contrast,the active contour model produces line image data along continuous visible curves such as wave crest profdes.The combination of these two existing techniques,the active contour model and Argus methodologies,facilitates the estimates of the direction wave field and phase speeds within the whole area covered by camera.These estimates are useful for the purpose of inverse calculation of the water depth.Applications of the present techniques to Hsi-tzu bay where a beach restoration program is currently undertaken are illustrated.This extension of Argus video techniques provides new application of optical remote sensing to study the hydrodynamics and morphology of a nearshore environment.  相似文献   

Estimating wave crest distributions using the method of L-moments     

Amir H. Izadparast  John M. Niedzwecki   《Applied Ocean Research》2009,31(1):37-43

The design of fixed or floating offshore structures requires accurate information of the met-ocean data at the intended offshore site. In the design process it is recognized that this environmental data is modified in the near-field by the interaction with the particular geometrical configuration of the offshore structure. This transformation of the incident wave field around and beneath an offshore structure presents a challenge for ocean engineers when specifying the wave gap elevation to avoid impact loads on the underside of the deck and inundation of the topsides. Thus, the accurate estimation of the wave crest distributions from measurements at various locations near and under the offshore structure during model test studies is essential. A semi-empirical approach is presented herein that builds upon the findings of previous studies and introduces the Method of L-moments. A three parameter model for a wave crest probability distribution function is presented and explicit relationships between the parameters of the distribution and its’ first three L-Moments are established. Furthermore, three narrow-band models from earlier research studies are reviewed and compared with the new model. Wave measurements from a mini-TLP model test program are used as the basis for comparison of the four distributions. The root-mean-square error is used as a metric to quantify the overall fit of the data and its accuracy in the high end tail of the data. The L-Moment model is shown to be more robust in representing the data in both the far-field and beneath the deck of the mini-TLP where the wave field demonstrates increased non-linear behavior.  相似文献   

一种实用的等值线型数据网格化方法   总被引：7，自引：2，他引：7  

郭志宏 《物探与化探》2001,25(3):203-208

数据网格化通常包括三大类:测线型数据网格化、等值线型数据网格化和离散点型数据网格化。文中研究的等值线型数据分块存储、网格点八方位搜索插值的网格化方法较好地解决了平面等值线型数字化数据的网格化计算问题,其计算数据量大,实用性强,精度高,计算速度快。  相似文献   

分析一维砂柱弥散试验数据的相关系数极值法   总被引：1，自引：0，他引：1       下载免费PDF全文

郭建青  马健  王洪胜 《水科学进展》2001,12(2):172-176

针对现有分析室内一维砂柱弥散试验数据,确定多孔介质纵向弥散度的方法,在考虑介质对示踪剂的吸附作用的情况下不能应用的问题,对描述一维、稳定渗流与连续定浓度注入示踪剂的砂柱弥散试验的近似解析解进行反函数变换,利用相关系数极值法的原理,建立了在多孔介质与示踪剂间为均衡吸附条件下,可计算多孔介质纵向弥散度与阻滞系数的方法.而且,这种方法在多孔介质的有效孔隙率为已知的情况下,还可计算出多孔介质对示踪剂的吸附系数.  相似文献   

稀土元素示踪法在坡面土壤侵蚀垂直分布研究中的应用   总被引：13，自引：1，他引：13       下载免费PDF全文

刘普灵  武春龙  琚彤军  杨明义 《水科学进展》2001,12(3):331-335

通过野外全坡长侵蚀小区试验,证明了稀土元素示踪法在土壤侵蚀垂直分布研究中的可应用性。结果表明该径流小区产沙强度坡长存在三种变化模式:增长型,增长 递减型和波动型,其形成机理可能与径流过程有关。利用稀土元素在坡面的再分析,初步建立了估算坡面沟蚀率的关系式。  相似文献   

Confidence Intervals of Quantiles in Hydrology Computed by an Analytical Method     

Baâ  Khalidou M.  Díaz-Delgado  Carlos  Caârsteanu  Alin 《Natural Hazards》2001,24(1):1-12

Fitting probability distributions to hydrologic data samples is widely used for quantile estimation purposes. The estimated quantile (X^_T) is related to a return period (T). The confidence interval associated with each of the estimates has been calculated empirically, up until now, supposing that the quantile estimator is normally distributed. In this study, it is shown that the confidence interval follows a normal distribution only in the central part of the distribution. The real confidence limits are computed analytically, by defining and integrating the probability density function of the confidence interval. The results with an important number of hydrologic samples show that the upper confidence limits are significantly underestimated towards the tail of the distribution, when determined using the normality approximation for the quantile estimator.  相似文献   

2050年前气候变暖冰川萎缩对水资源影响情景预估   总被引：42，自引：34，他引：42  

施雅风 《冰川冻土》2001,23(4):333-341

根据有不确定性的综合预测 ,到 2 0 5 0年左右青藏高原温度可比 2 0世纪末升高 2 .5℃左右 ,其导致冰川强烈消融的夏季升温为 1.4℃ ,将使平衡线上升 10 0m以上 .冰舌区消融冰量超过积累区冰运动来的冰量 ,冰川出现变薄后退 ,初期以变薄为主融水量增加 ,后期冰川面积大幅度减少 ,融水量衰退 ,至冰川消亡而停止 .考虑冰川大小 ,冰川类型响应气候变暖的敏感性有重大差别 ,应用新编中国冰川目录的统计数据 ,选择若干区域 ,预估 2 0 5 0年前冰川萎缩对水资源影响情景 .祁连山北麓河西地区 ,天山北麓准噶尔盆地南缘 ,天山南麓吐鲁番 哈密盆地的多数出山河流的冰川 ,以面积小于 2km2 者占绝对优势 ,对气候变暖最为敏感 ,衰退迅速 ,本世纪初期出现融水量高峰 ,中期融水量减少 ,对每条河流的影响以 10 6～ 10 7m3 ·a-1计 .少数流域如疏勒河、玛纳斯河等 ,冰川融水量占河川径流 1/ 3以上 ,有若干 5～ 30km2 左右中等规模冰川存在 ,预期至本世纪中期才出现融水高峰 ,融水增加值以 10 8m3 ·a-1计 .塔里木盆地周围高山冰川总面积达 2 2 0 0 9km2 ,有面积超过 10 0km2 、冰舌为厚表覆盖的大冰川 2 2条 ,退缩缓慢 ,冰川融水量在叶尔羌河、玉龙喀什河与阿克苏河等占 5 0 %～ 80 % .现在塔里木河干流主要靠天山西南部  相似文献   

Anisotropy of the upper mantle in Chinese mainland and its vicinity   总被引：2，自引：1，他引：2  

刘希强  周蕙兰  李红  季爱东 《地震学报(英文版)》2001,14(4):359-370

IntroductionAnisotropy is a universal phenomenon in the upper mantle. The mechanisms, which cause elastic anisotropy of in-situ rocks, include lattice preferred orientation of the minerals composing the rocks and preferred orientation of magma chambers. Lattice preferred orientation (LPO) of olivine is widely believed to be the dominant cause of the upper mantle anisotropy. The observational results of the upper mantle anisotropy can be explained by tectonic process relating to plate motion.…  相似文献   

The channel-geometry method: Guidelines and applications     

Geraldene Wharton 《地球表面变化过程与地形》1995,20(7):649-660

All river engineering schemes require flood discharge estimates as part of the design and appraisal process. Unfortunately, continuous measurement of flood discharges is limited to those river sites with instrumented gauging stations, which constitute only a small proportion of channel reaches where information is required. Therefore, considerable research effort has been devoted to the development of reliable indirect techniques of flood discharge estimation. Research on the interrelationship of stream channel geometry and river discharge has provided the basis for an indirect method of flood estimation – the channel-geometry method – which employs river channel dimensions alone to estimate discharge characteristics at ungauged river sites. Channel-geometry equations are developed empirically by relating streamflow data from gauging stations and channel dimensions measured from natural river reaches in the vicinity of the gauge, and take the form of power function relations. Once regional channel-geometry equations have been defined, a channel width or channel capacity measurement is the only variable needed to estimate the flood flow characteristics at a specified river site. The method is useful as an alternative to traditional catchment-based approaches or as a rapid reconnaissance technique. In addition to the application for flood discharge prediction, channel-geometry equations could prove helpful in the management of river channels, first, by providing a basis for assessing local deviations in the channel form–discharge relation, deviations which could be employed as indicators of the sensitivity of particular stretches of river channel to change, and secondly, in the computation of natural channel dimensions for use in river channel design and river restoration.  相似文献