共查询到20条相似文献，搜索用时 875 毫秒
1.
本论文在最大熵原理的基础上,通过解一个条件变分问题导出一种适用于描述非瑞利海浪波高H统计分布的概率密度函数fn(H)=αHre-βHn,用实验室风浪槽中不同风速下和不同风区处实测的36组风浪波高数据对上述概率密度函数进行验证,并与至今仍被广泛应用的瑞利波高概率密度函数加以比较.结果显示瑞利概率密度函数显著地偏离实验数据,而上述概率密度函数则与各组实测波高分布均符合良好. 相似文献
2.
3.
4.
本文通过分析实验室风浪周期分布,发现风浪周期累积概率分布曲线低于Longuet-Higgins理论结果,在小概率周期区域实验结果与理论结果的差异明显。对实验结果进一步分析发现,在谱不是很窄时,在小概率处风浪周期累积概率随谱宽度的增大而降低,这与窄谱假定下的理论结果相反,Longuet-Higgins理论结果在小概率处不便于描述周期分布随谱宽度的变化。根据实验结果提出风浪周期的Weibull分布经验公式,Weibull分布中的参数依赖于谱宽度。 相似文献
5.
胶州湾风浪波高和周期的分布 总被引：1，自引：0，他引：1
文章假足波浪要素的分布规律符合Weibull分布形式,根据胶州湾的实测资料,给出风浪波高和周期的分布函数,并计算出工程上常用的两种波高和周期与其平均值的关系。 相似文献
6.
基于最大熵原理的非Rayleigh海浪波高的统计分布 总被引：1，自引：0，他引：1
在最大熵原理的基础上,通过解一个条件变分问题导出一种适用于描述非Rayleigh海浪波高H统计分布的概率密度函数f4(H)=αHγe-βH4,并将其参量α,β,γ以H的1～4阶分布矩(Hm=m=1,2,3,4)显式地表示出来.用实验室风浪槽中不同风速下和不同风区处实测的36组风浪波高数据对上式进行验证,并与至今仍被广泛应用的瑞利波高概率密度函数加以比较.结果显示瑞利概率密度函数显著的偏离实验数据,而上式则与各组实测波高分布均符合良好. 相似文献
7.
8.
9.
利用有效波高和风速的3种概率密度函数分布:Rayleigh概率密度函数分布、Weibull概率密度函数分布、Log-Normal密度函数分布,结合TOPEX卫星高度计资料,对台湾岛周边海域的有效波高和风速进行分析比较.结果表明:有效波高的观测资料直方图与Log-Normal概率密度函数分布符合较好;而风速的观测资料直方图与Weibull概率密度函数分布符合较好.台湾岛周边海域的大部分海域以年变化为主,有效波高的平均值在冬季达到最大值,每年12月的平均值最大.每年平均有效波高最大值大多数出现在夏季,春季则是一年中有效波高平均值最小的季节,秋季和冬季则是巨浪出现频率较高的季节.同时,对有效波高平均值的时间序列做傅立叶展开表明,对应周期为1 a变化时的波动能量占每条轨道的波高波动能量的主要分量. 相似文献
10.
利用TOPEX高度计和NDBC浮标同步观测数据,对7种高度计海浪周期反演模型进行了系统的比较分析,从反演模式的精度、反演周期整体分布、周期-波高的联合分布等方面对反演模型做出了评价,并根据墨西哥湾和夏威夷海域反演结果对模型的区域适应性进行了验证,结合Hasselmann风浪充分成长关系分析了不同海浪成分下模型的反演效果.分析发现,Mackay等于2008年提出的算法(简称M08)相对于其他算法精度最高,且在不同海域和不同海浪成分下精度没有明显差异.利用M08算法反演了北太平洋海域的海浪平均周期分布,讨论其空间分布特征和季节变化特征如下:北太平洋海域的平均周期在墨西哥湾、西里伯斯海等沿岸地区较小,在西风带海域为较大,并存在明显的地形、纬度差异和季节性变化特征. 相似文献
11.
Longuet-Higgins(1983)[1]导出了波高与周期的联合分布函数,此分布函数虽然与实际数据符合良好,但存在很大的缺陷,如:由此分布函数得出的波高分布为形式较为复杂的非Rayleigh分布,很难应用于工程计算中。孙孚(1988a)[2]应用射线理论导出了一种波高与周期联合分布,虽然弥补了Longuet-Higgins的一些缺陷,但推导过程过于复杂。本文在窄谱假定下通过应用Hilbert变换方法得出新的分布函数并与前两者比较,表明Hilbert变换的方法不但简便,而且完全克服Longuet-Higgins的不足,可以方便的应用于工程计算中。本文也为Hilbert变换的方法在工程中的应用提供了理论依据。 相似文献
12.
This paper presents a method to statistically predict the magnitude of impact pressure (including extreme values) produced by deep water waves breaking on a circular cylinder representing a column of an ocean structure. Breaking waves defined here are not those whose tops are blown off by the wind but those whose breaking is associated with steepness. The probability density function of wave period associated with breaking waves is derived for a specified wave spectrum, and then converted to the probability density function of impact pressure. Impacts caused by two different breaking conditions are considered; one is the impact associated with waves breaking in close proximity to the column, the other is an impact caused by waves approaching the column after they have broken. As an example of the application of the present method, numerical computations are carried out for a wave spectrum obtained from measured data in the North Atlantic. 相似文献
13.
The relationship between significant wave height and period, the variability of significant wave period, the spectral peak enhancement factor, and the directional spreading parameter of large deepwater waves around the Korean Peninsula have been investigated using various sources of wave measurement and hindcasting data. For very large waves comparable to design waves, it is recommended to use the average value of the empirical formulas proposed by Shore Protection Manual in 1977 and by Goda in 2003 for the relationship between significant wave height and period. The standard deviation of significant wave periods non-dimensionalized with respect to the mean value for a certain significant wave height varies between 0.04 and 0.21 with a typical value of 0.1 depending upon different regions and different ranges of significant wave heights. The probability density function of the peak enhancement factor is expressed as a lognormal distribution, with its mean value of 2.14, which is somewhat smaller than the value in the North Sea. For relatively large waves, the probability density function of the directional spreading parameter at peak frequency is also expressed as a lognormal distribution. 相似文献
14.
Dong Hyawn KIM Taerim KIM 《中国海洋工程》2014,28(5):579-586
A new method of treating maximum wave height as a random variable in reliability analysis of breakwater caissons is proposed. The maximum wave height is expressed as the significant wave height multiplied by the so-called wave height ratio.The proposed wave height ratio is a type of transfer function from the significant wave height to the maximum wave height.Under the condition of a breaking wave, the ratio is intrinsically nonlinear. Therefore, the probability density function for the 相似文献
15.
A new method of treating maximum wave height as a random variable in reliability analysis of breakwater caissons is proposed. The maximum wave height is expressed as the significant wave height multiplied by the so-called wave height ratio. The proposed wave height ratio is a type of transfer function from the significant wave height to the maximum wave height. Under the condition of a breaking wave, the ratio is intrinsically nonlinear. Therefore, the probability density function for the variable cannot be easily defined. In this study, however, it can be derived from the relationship between the maximum and significant waves in a nonbreaking environment. Some examples are shown to validate the derived probability density function for the wave ratio parameter. By introducing the wave height ratio into reliability analysis of caisson breakwater, the maximum wave height can be used as an independent and primary random variable, which means that the risk of caisson failure during its lifetime can be evaluated realistically. 相似文献
16.
WANG Wei QIAN Chengchun
Professor Physical Oceanography Laboratory Ocean University of Qingdao Qingdao P. R. China
Associate Professor Physical Oceanography Laboratory Ocean University of Qingdao Qingdao P. R. China 《中国海洋工程》1999,(3)
Based on observed wind waves,the relationships between wave spectrum products and wavecharacteristics are established successfully,and the apparent energy distribution of sea waves is expressed as afunction of wave characteristics. 相似文献
17.
Elzbieta M. Bitner 《Applied Ocean Research》1980,2(2):63-73
This study deals with the non-linear effects of shallow-water wind waves. It is assumed that wind waves are an ergodic, random process, quasi-normal, stationary in time and homogeneous in space. The probability density function of sea surface oscillations is approximated by Gram-Charlier series in a modified form due to Edgeworth. Based on the above assumptions and on the fundamental statistical and stochastical laws the author has obtained the following characteristics: the probability density functions of wave heights, wave phases and velocity of the point mean wave height and mean wave length. The derived formulae are compared by the experimental data of the international expedition ‘Lubiatowo-74’. The analysis carried out has shown that real waves and the Gaussian model contradict considerably. 相似文献
18.
Variations are found in the shape and the steepness of wind-generated surface gravity waves between very young waves, such
as seen in a laboratory tank, and larger waves of various wave ages encountered at sea as the result of wind stress over larger
fetches. These differences in the characteristic shape of wind waves are presented as a function of the wave age. The wave
steepness is also expressed as a function of wave age, the measurement of which is consistent with the 3/2-power law connecting
wave height and characteristic period, normalized by the air friction velocity. 相似文献
19.
When waves impact a seawall, a vertical breakwater, an exposed jetty, a pier or a coastal bridge, they abruptly transfer their momentum into the structure. This energy transfer can be very violent and its duration exceptionally short. In the case of coastal bridges, whose spans are designed to have very short vibration period, wave impacts might have duration comparable to the natural period of oscillation of the structure, which therefore becomes prone to damage and failure. Previous forensic studies have documented the relative importance of impulsive loads on deck suspended structure, demonstrating the need to assess the effect of wave impacts on both the stability and the integrity of structural members since the early stages of the design. This requires the estimation of the dynamic characteristics of the loading pattern, and in particular the wave impulse and corresponding impact maxima and rise times. Based on the conservation of momentum, functional relationships between these parameters have been identified since pioneering work dating back to the late '30s of the 20th century. The complexity of the loading process, however, results in a significantly large variability of wave impact maxima and rise times even under similar conditions, suggesting the need for a probabilistic approach to the definition of the relationship between these two variables, to be applied when estimating the dynamic properties of wave for use in structural analysis of coastal structures. In the recent past, some effort has been made to identify functional relationships between such quantities; these require the assessment of the conditional quantiles (or similarly the conditional distribution) of wave impact maxima given the rise times. In this paper, we compare three different statistical methods proposed in the literature to accomplish this task, in order to assess the reliability of the approach and suggest guidelines for practical applications. A copula-based method, Generalized Additive Models for Location, Scale and Shape (GAMLSS), and quantile regression are applied to measurements from large-scale 3-dimensional physical model tests. The investigation suggests that quantile regression gives the simplest results to be used in practice; copula approach and GAMLSS are possible alternative when semi-parametric or fully parametric modeling is needed. 相似文献
20.
两参量的海面阻力系数模式的探讨 总被引：4，自引：0，他引：4
从风浪的能量平衡方程出发，引进若干风要素与波要素以及波要素之间的定性关系，经演算可导出海面阻力系数（Ｃｐ）或是风速（Ｕ）和波龄（β）或是Ｕ和波高（Ｈ）的函数，然后沿用最小二乘法，终将得出４组１２个回归方程。当β（或β）或Ｈ为某一给定值，惟有Ｕ为唯一参量时，所提各式均可简化为非线性方程：ＣＤ＝ａ＋ｂ，Ｕ＋ｃ．Ｕ＾２；式中ａ，ｂ和ｃ为三个经验系数，就所检验的例子而言，本文的结果与实际的符合前人的为好。 相似文献