共查询到18条相似文献,搜索用时 359 毫秒
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利用2009年1—6月的实测波浪资料,研究位于江苏北部辐射沙洲南部沿海测站的波浪特征。通过统计计算和研究分析,获得其波高特征值,并探讨各特征波高与平均波高(有效波高)之间的关系;筛选出25组有效波高出现极值时刻的波面资料,运用概率统计的方法计算了波高、周期及两者之间的联合概率密度分布,并与其对应的理论公式结果进行对比。结果表明:Gluhovski分布较适用于本地区的波高分布规律;当谱宽度较小时,Longuet-Higgins理论周期分布与实测分布比较符合;实测波高与周期联合概率分布对于大波高小周期的情况与各理论分布均吻合较好。 相似文献
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砰击颤振会威胁船体的总纵强度,本文先依据海况对响应贡献率最大的原则确定计算海况,然后计算得到一艘超大型集装箱船的波浪载荷时历,并采用Weibull、Gumbel以及GEV(Generalized Extreme Value distribution)分布拟合得到载荷短期极值沿船长的分布且校核了目标船的极限强度。本文通过短期极值Weibull、Gumbel分布拟合的结果与载荷的规范计算结果对比,发现有必要在考虑砰击颤振效应下利用波浪载荷直接预报结果校核目标船结构强度。 相似文献
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基于马尔可夫链的极值波高预测 总被引:1,自引:0,他引:1
本文研究了由日最大波高系列估算设计极值波高时,相邻日最大波高间的相关性对极值预测的影响,从日最大波高系列遵从马尔可夫链的假定出发,考虑到国内外经常采用对数一正态分布的韦布尔分布拟合波高长期分布的现实,本文用解析法求解了对数一正态分布情况下的极值预测。同时,对解析法难以求解的非正态随机变量情况(如韦布尔分布),用计算机随机模拟方法求解其极值预测,用上述两种方法对北大西洋和北海有关日最大波高系列的预测 相似文献
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鉴于未来全球气候变暖、台风强度和频次有逐渐加剧的趋势,建港地区工程风险须得到重视。在分析了珠江三角洲所受台风灾害的基本类型后,采用双层嵌套多目标概率模式及复合极值分布模型(MCEVD)对珠三角的台风灾害及超强台风进行了预测,并将计算结果应用于港区最大风速、波高、排水等方面的设计。该模型能全面系统地反映台风致灾的整体机制,在港口工程环境分析中得到了较好的应用。 相似文献
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Hamid Bazargan Hamid Bahai Amin Aminzadeh–Gohari 《Journal of Marine Science and Technology》2007,12(1):34-42
This study presents a new method for calculating return values. The essence of the method is that it utilizes nonstationary
data to calculate the return value for a region in the Northeast Pacific. The nonstationary data was obtained from a model
which was previously developed for the behavior of the significant wave height as a function of time in the region. The method
is illustrated by convolving two generalized Pareto distribution functions fitted to two parts of the model, computing a suitable
extreme value from the new distribution function, and calculating the return value using this extreme value. 相似文献
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王言英 《船舶与海洋工程学报》2008,7(3):162-167
In order to respond the discredit on the design wave standard and to recommend new consideration on design wave parameters, based on the long-term distribution of statistic characteristics of waves and the short-term probability properties of sea state defined by giving the return period, the calculation of the return period, the height, the period, and the oceanic wave parameters of the design wave and the forecasting methods are discussed in this paper. To provide references for the operation reliability of floating structures in the extreme sea state, the method of determining the design wave parameters is resurveyed. A proposal is recommended that the design wave, which can be either significant wave with 500-year of the return period, or the maximum wave with 1/N of exceeding probability, 100-year of the return period, can be applied in the engineering design practice. 相似文献
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在吉布提LNG厂址的设计过程中,由于当地可用水文资料缺乏,现场观测活动起步晚、持续时间短(仅1 a),无法满足多年重现期设计波浪要素推算的需求,给后续工作带来了较大的困难。以CCMP风场数据作为驱动,基于波作用量平衡方程建立印度洋大范围波浪数学模型、嵌套的亚丁湾中等范围模型及工程区小范围模型,在现场实测资料的基础上,结合同期的Jason卫星轨道资料对模型进行验证对比,模型验证结果良好。在此基础上,计算了1988—2017年的逐时波浪要素过程,并据此构建出年极值波浪序列,利用P-III型分布函数推算工程区深水处的各重现期波浪极值,结合不同水文条件计算得出工程区的设计波浪要素。 相似文献
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Hiroshi Kawabe 《Journal of Marine Science and Technology》2002,6(3):135-147
This report is concerned with the statistical analysis of the long-term distribution of a wave-induced load, and examines
which factors influence the long-term distribution of the load level, e.g., the significant wave height, the mean wave period
of the supposed wave condition, and the relative angle between the ship's course and the wave direction. The long-term distribution
is broken down into these factors, and a contribution rate analysis method for each factor in each load level in the long-term
distribution is introduced. Based on the method used, the contribution rate of a specific mean wave period and a wave angle
encountered is clarified, when the long-term distribution is larger than other wave periods and wave angles. The specific
mean wave period and wave angle encountered are defined as the wave condition which governs the long-term distribution. The
maximum wave-induced load in the vicinity of a probability of exceedance of around 10−8 in the long-term distribution is decided by the most severe short-term wave condition which has the largest significant wave
height with a specific mean wave period. Based on S–N curves and Miner's rule, the relation between the fatigue damage and the supposed wave condition is examined. The contribution
rate analysis method for fatigue damage is introduced. The governing wave condition and the most severe short-term wave condition
also have an important effect on the fatigue damage. A simple estimation method for the long-term distribution, described
by the Weibull distribution from the statistical properties of the most severe short-term wave condition, is introduced. Several
examples show the applicability of the estimation method.
Received: November 22, 2001 / Accepted: January 9, 2002 相似文献
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Longitudinal stresses due to combined horizontal and vertical bending moments in ships, corresponding to a return period
of 20 years, are estimated by linear response analysis. In principle, the stress should be obtained by combining the stress
in all sea states that can occur over a long-term period. A method to determine the desired long-term extreme stress by considering
only a few short-term sea states is presented. The sea states have a certain probability of occurrence, and are each identified
by a contour line in the (H
s, T
p)-plane. This approach makes it possible to estimate the extreme loads on the vessel in a practical and accurate manner. Moreover,
it is shown that the long-term stress can be estimated by combining the individual long-term extreme stresses due to vertical
and horizontal bending moments by using the sum-of-squares approach and accounting for the correlation between stresses. It
was found that the correlation coefficient can be taken as the largest of the ones calculated along the contour line. It is
shown that this correlation coefficient can even be approximated by the normalized phase angle at the wave length where the
dominant response has its peak value. A comparison with the results obtained using well-known combination rules is presented.
While linear analysis has been used here, it is believed that the approach can be generalized to stresses with nonlinear behavior,
and hence represent a significant improvement in calculation efficiency.
Received: September 18, 2001 / Accepted: December 18, 2001 相似文献
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基于MIKE21-BW模块,采用多种概化处理模型,研究了烟台港某工程港内波高分布和波浪传播状况。通过与物理模型进行对比,分析了各概化模型的优缺点,选择较优方案。结果表明:对于整个港池波高分布情况,各方案数学模型模拟结果和物理模型试验结果基本吻合,均能较好反映波高分布趋势及一些较复杂波浪传播变形现象。但其中存在多种波浪组合,同时包括波浪折射、反射、绕射、破碎、爬坡且反射波占主导地位的局部水域,数学模型模拟的波高数值都与物理模型结果相去甚远,说明MIKE21-BW仍不能很好模拟此类复杂波况水域。 相似文献
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斜坡堤胸墙对于减轻越浪危害至关重要,国内外各胸墙波浪力计算方法的结果差异较大。基于国内外几种斜坡堤胸墙波浪力计算方法,结合工程案例和试验数据进行对比研究。结果表明:1)特定条件下,我国规范计算的水平波浪力压强分布高度远小于Jensen法和Pedersen法结果,后两法计算结果与实测高度一致。2)Jensen法和Pedersen法计算的水平波浪力及浮托力均比国内港工方法大,也大于实测值。3)港工规范计算的总水平波浪力比实测值小,其计算出的浮托力与实测值较为接近。4)Jensen法考虑了掩护棱体肩台高度的作用,Pedersen法考虑了掩护棱体肩台高度与宽度的影响。此二法考虑得相对全面,但其按深水波长计算0.1%超越概率的波浪力,计算结果偏于保守。5)建议重要工程以模型试验结果为准。 相似文献