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1.
M.Aziz Tayfun 《Ocean Engineering》1984,11(3):245-264
The effect of nonlinearities, such as wave-breaking and vertical asymmetry associated with sea waves, on the distribution of wave amplitudes is explored. Semiclosed theoretical expressions are derived to describe the distributions of breaking-limited crest and trough amplitudes for Stokes-type nonlinear sea waves. These are compared with the conventional Rayleigh distribution appropriate to linear wave amplitudes. The construction of nonlinear wave envelopes with the fast Fourier transform technique is described. The technique can be utilized to enlarge the data base in empirical analyses of field records which typically contain limited information on amplitude characteristics. The theoretical distributions and the proposed data enlargement technique are demonstrated with the analysis of a nonlinear wave record. 相似文献
2.
M. Aziz Tayfun 《Ocean Engineering》1983,10(2):107-118
The statistical distribution of the crest-to-trough heights of narrowband nonlinear sea waves is derived in a semi-closed form. A quantitative comparison of the resulting density and exceedance probability distributions with those of the linear theory is given. It is shown that the nonlinearity of waves, even with steepnesses typical of extreme sea states, has an insignificant influence on the distribution of crest-to-trough heights. 相似文献
3.
Simultaneous measurements of wind velocities at two different sites, one over the sea and the other over land, can differ substantially and therefore cannot be interchanged. In situations where the wind data at an offshore site are missing while simultaneous measurements from a land-based station exist, a linear mean-square estimation (LMSE) technique can be used to estimate the missing data. This technique relies on past wind data gathered simultaneously at the two locations, and it generates from the associated correlation a set of four transfer functions capable of predicting one data set from the other. In the present case, the LMSE technique is outlined briefly, and is then applied to construct seasonal transfer functions between a land-based station and two coastal/offshore sites in Kuwait. Comparisons between the actually observed wind characteristics and those predicted by the LMSE technique are favorable, and thus tend to confirm the applicability of the technique under appropriate conditions. 相似文献
4.
The distribution of nonlinear wave crests is examined on the basis of a theoretical probability density previously given elsewhere (J. Eng. Mech. 120 (1994) 1009). Certain errors contained in the original theoretical density are corrected, and the corresponding exceedance distribution is derived. The resulting theoretical forms of the probability density and exceedance distribution are then slightly simplified and compared with nonlinear wave data gathered under hurricane conditions. The results indicate that the proposed theoretical forms describe the observed distributions of large wave crests better than the Rayleigh law. However, the quantitative accuracy of the predictions is somewhat poor, as is typical of approximate theories based on Gram–Charlier-type expansions. 相似文献
5.
Statistics of nonlinear wave crests and groups 总被引：1，自引：0，他引：1
Groups of large nonlinear waves with sharper higher crests can pose hazards to ships, induce harbor resonance and cause wave-overtopping of fixed and floating structures. Past interest in wave groups has mostly been focused on the statistics and modeling of linear wave groups. Studies on nonlinear wave groups are surprisingly few, and address deep water waves only. Here, statistics of nonlinear wave crests and wave-crest groups in deep and transitional water depths are considered, using an appropriate second-order representation for crest heights and the continuous wave-envelope approach. In particular, theoretical expressions describing the statistics of nonlinear wave crests and their groups are posed in the form of a simple second-order transformation of well-known results on linear waves. Predictions from the transformation so posed compare well with nonlinear wave data gathered in the North Sea, and demonstrate that nonlinearities do affect the statistics of large wave crests and their groups significantly. 相似文献
6.
Refraction of incoherent random gravity waves with currents and bottom topography results in spatial variations in the spectral characteristics of the free surface. Prediction of such variations based on the radiation transfer equation is in a simple analytic form for the case of one dimensional inhomogeneities in currents and topography. This analytic form is examined in terms of two-dimensional wave number- and polar frequency-direction spectra along the associated dynamic and kinematic constraints relevant to wave breaking and reflection. Results are specialized to the simplest case of horizontal shear currents in deep and shallow water with explicit examples to illustrate the relative and combined effects of currents and topography on free surface spectra. 相似文献
7.
A severe sea-effect snow episode over the city of Istanbul 总被引：1，自引：0，他引：1
Tayfun Kindap 《Natural Hazards》2010,54(3):707-723
In February 2005, unexpected heavy snowstorms lasted a couple of days with changing intensities, producing significant snowfall that eventually paralyzed the life of Istanbul metropolis. Surprisingly, there was no caution announcement prior to the onset of this unusual weather phenomenon. What was the reason behind this wrong prediction? In this case study, using a meteorological model, a heavy sea-effect snowfall, the reason of this phenomenon, was simulated and researched. With a persistent surface high-pressure center over western Russia, a surface low-pressure positioned in the center of southern Turkey was the dominant feature of the formation of the sea-effect snow over the city. In addition to strong northerly winds (19 m/s), low directional vertical wind shear (<30o) and extremely long fetch distance (~600 km) feature; environmental conditions during the event were characterized by a sea-surface 850-hPa temperature difference of up to 14°C and a sea–land temperature difference as high as 24°C. 相似文献
8.
Huseyin Ozdemir Alper Unal Tayfun Kindap Ufuk Utku Turuncoglu Zeynep Okay Durmusoglu Maudood Khan Mete Tayanc Mehmet Karaca 《Theoretical and Applied Climatology》2012,108(1-2):31-38
The Anatolian Peninsula is located at the confluence of Europe, Asia, and Africa and houses 81 cities of which 79 of them have population over 100,000. We employed some criteria to select the cities from the 81 cities. After accomplishing all the criteria, eight cities were remaining for the study. Nonparametric Mann–Kendall test procedure was employed for the urban and rural stations of these cities to detect the long-term change in temperature trends. Statistical analysis of daily minimum temperatures for the period between 1965 and 2006 suggest that there is no statistically significant increase in rural areas. In contrast to the findings of the previous studies, however, all the urban sites and difference between urban and rural pairs show significant increase in temperatures, a strong indication for the existence of urban heat island (UHI) affect over the region. Regional Climate Model was also utilized to assess the changes in temperature by the end of century for the region. The findings suggest that an increase of up to 5°C is possible. Climate change effects enforced with UHI have the potential to cause serious problems for the entire region and hence needs to be studied thoroughly. 相似文献
9.
Mineral resource evaluation requires defining grade domains of an ore deposit. Common practice in mineral resource estimation
consists of partitioning the ore body into several grade domains before the geostatistical modeling and estimation at unsampled
locations. Many ore deposits are made up of different mineralogical ensembles such as oxide and sulfide zone: being able to
model the spatial layout of the different grades is vital to good mine planning and management. This study addresses the application
of the plurigaussian simulation to Sivas (Turkey) gold deposits for constructing grade domain models that reproduce the contacts
between different grade domains in accordance with geologist’s interpretation. The method is based on the relationship between
indicator variables from grade distributions on the Gaussian random functions chosen to represent them. Geological knowledge
is incorporated into the model by the definition of the indicator variables, their truncation strategy, and the grade domain
proportions. The advantages of the plurigaussian simulation are exhibited through the case study. The results indicated that
the processes are seen to respect reproducing complex geometrical grades of an ore deposit by means of simulating several
grade domains with different spatial structure and taking into account their global proportions. The proposed proportion model
proves as simple to use in resource estimation, to account for spatial variations of the grade characteristics and their distribution
across the studied area, and for the uncertainty in the grade domain proportions. The simulated models can also be incorporated
into mine planning and scheduling. 相似文献
10.
Vessel accidents during stormy weather conditions over Kuwait's coastal waters are one of the major concerns for insurance and re-insurance companies, since such accidents can result in not only material losses but also losses of lives. In order to determine insurance rates for different types of vessels and their operators, it is desirable to estimate the risk or probability of occurrence of an accident and the resulting expected damage or losses associated with a given vessel type under the local wave conditions first. Therefore, there is a national need for such a study to provide this type of basic information on the risks or probabilities of vessel accidents caused by high waves within the Kuwait's territorial waters. The main objective of this study is thus to provide such information for the local and international agencies and companies concerned with sailing operations and maintenance, navigational safety, and particularly insurance of small recreational and commercial vessels. The study was carried out with the financial support of M/s Warba Insurance Company and the Kuwait Foundation for the Advancement of Sciences, Kuwait. 相似文献