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31.
This study investigates experimentally the breaking wave height of multi-directional random waves passing over an impermeable submerged breakwater. Experiments have been conducted in a three-dimensional wave basin equipped with a multi-directional random wave generator. A special type of wave gauge has been newly devised to record the water surface elevations in the breaker zone as accurately as possible. The records are analyzed to estimate the location and limit of wave breaking. Comparisons have also been made with the results of regular waves. The influence of the incident wave conditions on the breaking wave height normalized by the breakwater dimensions has been investigated. Empirical formulae have been presented to estimate the breaking limit of multi-directional random waves based on the experimental records. The formulae have been tested and found to work well not only for multi-directional random waves, but for regular waves as well. 相似文献
32.
- In order to employ cost effective frequency domain analysis for off-shore structures treatment of hydrodynamic loading is essential. Drag and inertia dominated, resonating and antiresonating cases under random sea states are analyzed to highlight the implications and relative merits of four salient linearization techniques. 相似文献
33.
本文在作者另文数值模拟得到的三维海浪基础上 ,进一步分析给出了三维波峰长度、高度及方向角度等特征量的统计分布。发现考虑海浪的方向性质后波峰分布不再是均匀连续的 ;波峰的长度分布受方向函数影响 ,方向分布越宽 ,波峰的平均长度越短 ,波峰的方向角分布越宽 ;波峰高度和长度在波峰高度较小时有很大的相关性 ,而在波峰高度很大时无关 相似文献
34.
A new approach for the solution of the two-dimensional guillotine-cutting problem in ship production
A. Cemil Dikili 《Ocean Engineering》2004,31(8-9):1193-1203
A new approach has been developed for the arrangement of rectangular pieces in plates for the guillotine-cutting problem as encountered in ship production and similar manufacturing processes. The algorithm is quite novel in the sense that instead of making preliminary specifications and ignoring all the alternative arrangements, as is the case for most of the current models, it selectively considers feasible arrangements by eliminating the majority of the probable arrangements that render the problem insolvable. Intermediate steps of the algorithm produce results which cannot be obtained through integer programming. Losses are distributed to the minimum number of plates. The number of arrangement plans is also minimized. Overall the solution of the problem has been drastically simplified to allow even hand calculations instead of long computer runs. 相似文献
35.
The indicator kriging (IK) is one of the most efficient nonparametric methods in geo-statistics. The order relation problem in the conditional cumulative distribution values obtained by IK is the most severe drawback of it. The correction of order relation deviations is an essential and important part of IK approach. A monotone regression was proposed as a new correction method which could minimize the deviation from original quintiles value, although, ensuring all order relations. 相似文献
36.
The Bayesian detection of discontinuities in a polynomial regression and its application to the cycle-slip problem 总被引:4,自引:1,他引:3
Maria Clara de Lacy Mirko Reguzzoni Fernando Sansò Giovanna Venuti 《Journal of Geodesy》2008,82(9):527-542
This paper deals with the problem of detecting and correcting cycle-slips in Global Navigation Satellite System (GNSS) phase
data by exploiting the Bayesian theory. The method is here applied to undifferenced observations, because repairing cycle-slips
already at this stage could be a useful pre-processing tool, especially for a network of permanent GNSS stations. If a dual
frequency receiver is available, the cycle-slips can be easily detected by combining two phase observations or phase and range
observations from a single satellite to a single receiver. These combinations, expressed in a distance unit form, are completely
free from the geometry and depend only on the ionospheric effect, on the electronic biases and on the initial integer ambiguities;
since these terms are expected to be smooth in time, at least in a short period, a cycle-slip in one or both the two carriers
can be modelled as a discontinuity in a polynomial regression. The proposed method consists in applying the Bayesian theory
to compute the marginal posterior distribution of the discontinuity epoch and to detect it as a maximum a posteriori (MAP)
in a very accurate way. Concerning the cycle-slip correction, a couple of simultaneous integer slips in the two carriers is
chosen by maximazing the conditional posterior distribution of the discontinuity amplitude given the detected epoch. Numerical
experiments on simulated and real data show that the discontinuities with an amplitude 2 or 3 times larger than the noise
standard deviation are successfully identified. This means that the Bayesian approach is able to detect and correct cycle-slips
using undifferenced GNSS observations even if the slip occurs by one cycle. A comparison with the scientific software BERNESE
5.0 confirms the good performance of the proposed method, especially when data sampled at high frequency (e.g. every 1 s or
every 5 s) are available. 相似文献
37.
基于波作用量守恒方程建立了波流共存场中多向随机波浪传播变形数学模型,模型中考虑了波浪绕射的影响和水流引起的波浪弥散多普勒效应,应用包含水流和地形影响的激破波模式计算波浪破碎的能量耗散,采用一阶上迎风有限差分格式离散控制方程。分别计算了有无近岸流情况下单向和多向随机波浪的波高分布,考虑水流影响的数值计算结果与物理模型实验数据吻合良好,比较分析表明,所建立的数学模型能够复演由于离岸流引起的波高增大,可用于波流共存场多向随机波浪传播变形的模拟和预报。 相似文献
38.
利用参考重力场模型基于能量法确定GRACE加速度计校准参数 总被引:1,自引:0,他引:1
利用多个参考重力场模型分别对GRACE一个月的实测加速度计观测数据进行检校.数值计算结果的比较分析表明了利用参考重力场模型确定加速度计校准参数是有效的. 相似文献
39.
Mauro Cacace Ulf Bayer Anna Maria Marotta 《International Journal of Earth Sciences》2008,97(5):899-913
The large-scale crustal deformations observed in the Central European Basin System (CEBS) are the result of the interplay
between several controlling factors, among which lateral rheological heterogeneities play a key role. We present a finite-element
integral thin sheet model of stress and strain distribution within the CEBS. Unlike many previous models, this study is based
on thermo-mechanical data to quantify the impact of lateral contrasts on the tectonic deformation. Elasto-plastic material
behaviour is used for both the mantle and the crust, and the effects of the sedimentary fill are also investigated. The consistency
of model results is ensured through comparisons with observed data. The results resemble the present-day dynamics and kinematics
when: (1) a weak granite-like lower crust below the Elbe Fault System is modelled in contrast to a stronger lower crust in
the area extending north of the Elbe Line throughout the Baltic region; and (2) a transition domain in the upper mantle is
considered between the shallow mantle of the Variscan domain and the deep mantle beneath the East European Craton (EEC), extending
from the Elbe Line in the south till the Tornquist Zone. The strain localizations observed along these structural contrasts
strongly enhance the dominant role played by large structural domains in stiffening the propagation of tectonic deformation
and in controlling the basin formation and the evolution in the CEBS. 相似文献
40.