Academic literature on the topic 'Wave motion characteristics'

The dynamic response characteristics of a two-dimensional submerged floating tunnel (SFT) under random and freak waves were investigated in the present study. The results demonstrate that (1) the dynamic responses of the SFT under the freak wave are significantly larger than those under the largest wave in the wave train excluding the freak wave, particularly for the motion response. The maximum values of the motion responses induced by the freak wave were several times larger than those induced by the largest wave in the wave train excluding the freak wave, far exceeding the proportion of the corresponding wave height. (2) The freak wave parameter α1 has a significant effect on the amplification coefficients of surge, heave and pitch; all increase nonlinearly as α1 increases. Within α1 = 1.90~2.59, the amplification coefficients of the surge, heave and pitch vary in the ranges of 1.91~6.46, 1.53~3.87 and 1.73~5.32, respectively. (3) Amplification coefficients of tension increase almost linearly as α1 increases. Additionally, the amplification effect of the freak wave on the mooring tension is much smaller than that on motion responses. Within α1 = 1.90~2.59, the amplification coefficients of tension vary from 1.15 to 1.35. (4) Generalised amplification coefficients of motion responses increase as α1 increases and are all greater than 1.0, indicating that growth rates for motion responses under the freak wave exceed the growth rates for maximum wave height. Moreover, motion responses show a significantly nonlinear growth as maximum wave height increases. The generalised amplification coefficients of the mooring tension decrease as α1 increases, and are all less than 1.0, indicating that the dynamic amplification effect of the freak wave on the mooring tension is much smaller than that on motions. On the other hand, growth rates of the mooring tension under freak waves are smaller than the linear growth rate of the height of freak waves.

The purpose of this study was to investigate the wave characteristics of breaststroke swimming. Particular emphasis was accorded the question of whether modern breast-stroke is "flylike" (referring to the butterfly stroke) and whether "waves" travel along the body during the breaststroke cycle. Selected body landmarks and the center of mass (CM) of 8 Olympic breaststroke swimmers were quantified. Fourier analysis was conducted to determine the amplitude, frequency composition, and phase characteristics of the vertical undulations of the vertex of the head, shoulders, hips, knees, and ankles. The differences in phase between these landmarks for the first (HI) and second (H2) Fourier frequencies were investigated to establish whether body waves traveled in a caudal direction. While the motion of the upper body was somewhat flylike, the velocity of the HI wave from the hips to ankles was variable among subjects and, for all subjects, was too slow to be propulsive. Contrary to what one would expect, the range of vertical motion of the CM was inversely related to the range of hip vertical motion. The two highest placing subjects, based on preliminary heat times (SI and S4), were distinguished by a large range of hip vertical motion and a small range of CM vertical motion.

Site characteristic period is an important index in seismic zonantion and seismic resistance design. The characteristics of the ground motions are conceptually related with site characteristics. A simplified single-layer model is used for simulating horizontal strata under seismic loading to calibrate the correlation of site characteristic period with the predominant period of ground motion. The analytical results show that the inputted motions were amplified considerably by the site typically for the period components which were close to the site characteristic periods; with the shear wave velocity of the soil layer decreases with respect to the initial shear wave velocity, the predominant period of ground motion increases; the site characteristic periods are consistent with the predominant periods of the ground motion.

To study motion range changes with wave condition and motion relationship between cages, physical model experiments were carried out. The authors designed 2 models of composite-type sea cages. Experimental data obtained by the CCD data acquisition system. The experiment results showed that 1.in the same period, horizontal motion range,vertical motion range and inclination changes of float collar increase with wave height; 2.In the same wave height, horizontal motion range of the float collar increases with period; 3.The laws between vertical motion and period are not obvious 4.The laws between inclination changes and period are not obvious 5.Motion range of the first cage along the direction of waves is less than other cages.

The offshore wind turbine (OWT) supported by bucket foundations can be installed in the integrated transportation process by a dedicated vessel. During the integrated transportation process, the wind turbine is considered as a coupling system with the transport ship, which is easily influenced by waves and storms. In view of the motion response and influential factors, the heave and rock stiffness of the entire floating system was proposed, and then the analytical dynamic motion model of the coupling system was established based on the movement mechanism of the traditional floating body in the wave in this paper. Subsequently, the rationality of the proposed motion model was verified based on the field observation data, with the maximum deviation of the motion responses less than 14%. Further, the influence on the heave and pitch motion of the coupling system considering different factors (vessel speed, wave height, wind speed and wave angle) and the factor sensitivity were discussed by the novel analytical model. It is explained that the heave and pitch motion responses rise with the increase of the wave height and wave angle. Simultaneously, the responses decrease as the vessel speed increases considering sailing along the waves. On the contrary, the responses show an obvious increasing trend with the increase of vessel speed in the case of the top wave sailing. In addition, it is also illustrated that the wave height has the greatest influence on the heave and pitch motion responses, followed by the vessel speed. The wave angle has the lowest sensitivity when the heave and pitch motion are far away from its harmonic resonance region.

In order to study the far-field ground motion characteristics and the attenuation of seismic waves, the peak ground acceleration (velocity, displacement), time of duration and response spectrum of the seismic waves were analyzed in this paper. Through the investigation of earthquake wave propagation process, the seismic attenuation low was analyzed. This study can provide technical support for the seismic design of long period structures and related engineering application.

Newton mechanics is great, Newton's contribution is indelible. But from Newton's classical mechanics, the definition of velocity (=) must mean that this physical parameter is a vector, so "negative velocity" only means the opposite direction of motion, no other meaning. It is difficult to understand negative velocity within the framework of classical mechanics. However, wave is a special form of material motion, wave mechanics has a unique method and meaning, and its concept and connotation are significantly different from classical mechanics. For example, wave velocity (whether phase velocity or group velocity) is a scalar quantity. "Negative wave velocity" does not mean that the direction of motion is reversed, but a special phenomenon that does not accord with causality from the surface view. In any case, research in recent decades has shown that negative wave velocity is not only theoretically possible, it has also been repeatedly shown to exist experimentally. Moreover, negative wave velocity is a special form of superluminal speed; The wave with negative velocity is the advanced wave. It corresponds to the leading solution of the basic equation of electromagnetic field and electromagnetic wave. The past practice (discarding the advanced solution) is wrong! As for causality, scientists have provided a new definition and interpretation. In short, both wave mechanics and quantum optics take a different approach from classical mechanics.
 This paper points out that it is unusual for the 2022 Nobel Prize in Physics to be awarded to Alain Aspect and two others, since Aspect's experiments on the Bell inequality were completed in 1982, Which still stands today as a crucial experiment that proved Einstein's EPR paper wrong and quantum mechanics (QM) correct. Aspect's award in 2022 showed that mainstream physical community had been forced to accept that quantum entanglement existed and that the "light-speed limit" theory of SR was a mistake.
 This paper discusses the proposition "negative characteristic motion of electromagnetic wave" put forward by the author in 2013, pointing out that it is an inherent physical phenomenon reflecting symmetry in nature. In this paper, the faster-than-light motion of waves found in the near-field of antennas is discussed. In addition, the realizability of "time travel" is also discussed.

This paper proposes to carry out experiment procedures to investigate the translation motion characteristics of symmetrical semi-submersibles in long crest regular waves. The hydrodynamic response of floating structures in waves is required to be modelled correctly to ensure stability and safety. The symmetrical semi-submersible model was constructed based on a scale ratio of 1:81 in this experiment and was installed with horizontal mooring lines in a wave dynamic basin. This paper also discusses the model preparation procedures, including the mooring lines setup, instrument setup and experiment setup, before conducting the experiment. According to the experiment data, the symmetrical moored semi-submersible experienced wave frequency motion and slow varying motion due to drift force and mooring lines for sway motion; while the heave and surge motion only experienced wave frequency motion.

The possible motions of caisson breakwaters under dynamic load excitation include vibrating motion, vibrating–sliding motion, and vibrating–rocking motion. Three models are presented in this paper and are used to simulate the histories of vibrating–sliding–rocking motions of caissons under breaking wave impact. The effect of the dynamic characteristics of the caisson–foundation system and the motions on the displacement, rotation, sliding force, and overturning moment of caissons are investigated. It is shown that the sliding force of the caisson is different from the breaking wave force directly acting on the caisson due to the motion of the caisson and the sliding motion or rocking motion of the caisson can limit the sliding force or overturning moment of the caisson to a certain value. The sliding force never exceeds the friction force between the caisson and the foundation, and the overturning moment never exceeds the stability moment of the caisson. It is concluded that the wave conditions, the dynamic characteristics, and the motions of the caisson–foundation system should be considered in design.Key words: caisson breakwater, breaking wave, vibrating, sliding, rocking.

This paper aims to investigate the nonlinear motion characteristics of a monocolumn type floater with skirts numerically and experimentally. Wave calibration, free decay, and regular wave tests were simulated using a computational fluid dynamics (CFD) code OpenFOAM. The experiments were carried out in a wave tank to validate the CFD results. First, wave calibration tests were performed to investigate wave generation, development, propagation, and absorption in the numerical wave tank. Second, the simulation input parameters were calibrated to reproduce the waves generated in the tank experiment. Third, free decay tests of heave and pitch were conducted to examine the natural period and the linear and quadratic damping of the floater. A verification and validation study was performed using experimental data for free decay tests. Finally, regular wave tests were performed to investigate the motion characteristics of the floater. The results were processed to obtain the response amplitude operator (RAO) for the heave and pitch motions. The RAOs of the floater was compared with the experimental data and numerical simulations based on the linear potential theory code WAMIT to investigate the performance of the CFD simulations. The comparisons made in this work showed the potential of the CFD method to reproduce the motion characteristics of a shallow-draft floating object with a skirt in waves and to visualize the nonlinear phenomena behind the oscillation of the floating object.