Peak wave period

Peak wave period (7),) is the period at which the peak energy occurs. For many sites a reasonable estimation is = O.STp but can commonly vary fi-om 0.65 to 0.9. 

Equation (15.19) is only valid for a down slope of 1 1.25 and an upper slope of 1 1.25. For other slopes, one has to reshape the slope to a slope of 1 1.25, keeping the volmne of material the same and adjusting the berm width B and for the upper slope also the crest width Ge- Note also that in Eq. (15.19), the peak wave period... 

A linear interpolation between the two is performed in the range 8 < Be/ Hsi < 12. In Eqs. (22.5) Rc is the structure freeboard (negative for submerged structures), Be is the crest width, and op is the surf similarity parameter based on structure offshore slope and peak wave period. Equations (22.5) were applied in the range —5 < Re/Hsi < 5. 

The wave energy is relatively large in summer, the peak value of frequency spectrum is 1.00 mVHz, peak-period corresponds to 8 s, and it means the wave has the characteristic of big wave height and short wave period. 

The frequency spectrum peak value in spring, autumn and winter are all below 0.02 mV Hz, corresponding spectrum peak period between 11 13 s, and it means the wave has the characteristic of small wave height and long wave period. 

For the study on the bifurcation into the ten-peak wave or the nine-peak wave, we investigate the temporal variations of the correlation coefficients of these five waves, i.e., the time-resolved correlation coefficients of these waves. For the time-resolved correlation coefficients, the periods of these five waves are plotted as a function of time, i.e., the peak positions of the waves, as shown in Fig. 18. In this figure, the abscissa is divided into eight sections by 10 ms. The time-resolved correlation coefficients are obtained by calculating the correlation coefficients of these curves in Fig, 18 in the individual sections of the abscissa and shown in Fig. 19. In Fig. 19, the time resolved correlation coefficients of waves 2-5 with wave 1 are shown, where the coefficients of the waves are normalized to be 1 at 10 ms, i.e., in the section between 10 and 20 ms. 

In calculating the maximum wave periods a value of 1.2 times the significant wave period is normally used for deep water for calculation of the minimum wave period, the limitation of wave steepness in shallow water is appropriate. The significant wave period may be taken to be approximately the same as the average wave period. The peak period of the waves in shallow water can be up to twice the mean period. 

Standard terminology defines the water level in the absence of wave effects as still water level, whereas wave setup will cause a departure from the still water level and this water level including the effects of the waves is the mean water level. As implied, the mean water level is determined as the average of the fluctuating water level over a suitable time frame usually taken as a number of multiples of the short wave period, say the spectral peak. In considering wave setup, often the location of interest is that of the maximum wave setup at the shoreline. This raises the question of whether wave setup is defined at elevations above the maximum rundown, say on the beach face where the water is present over only a portion of the wave period. Since wave setup is defined as the mean water level, over what period should the water surface be averaged on the beach face which is wetted over only a portion of the wave period If the time average is over only the portion of the period that water is present, in the upper limit, the maximum setup will be the maximum runup. For purposes here, wave setup will usually be defined only for conditions where water is present over a full wave period. 

The input parameters are wave height, wave period (either spectral period Tm-1,0 or peak period Tp), wave obliquity, water level (with respect to the same level as used for the structure geometry), and finally, number of waves (derived from the storm duration and mean period) for the calculation of overtopping volumes, etc. Fig. 14.16 gives the input file. 

Lop = gTp I 2tt), deep-water wavelength at the peak period (m), and Tp = wave period at the peak of the spectrum (s) and b = exponent 0.5 < 6 < 1.0. For porous top layers, such as sand mattresses and gabions, the relative density of the top layer must be determined, including the water-filled pores ... 

The model for the present condition is simulated and compared with the field data measured by HMTC during typhoon Tim in July 1994. The model results and field data at station 22 and 8 are presented in Fig. 25.16. It shows the amplification factor as a function of the incident wave period. It is seen that the comparison is quite good with respect to resonant periods, resonant bandwidth, and peak amplification factors. The results clearly indicate that there exists a broadband of resonant response for wave periods between 100 and 160 s and the computer model results appear to have captured the resonant modes correctly. 

Figure 1.20 Cont d. (v) Square wave voltammetry (a) anodic scanning of the potential (b) plot of vol-tammogram (SP, Start potential EP, End potential to and tf, starting and final time of the scanning io, current at the beginning of the scanning ip, peak current Ep, peak potential AT, sampling time CR, Current range WA, Wave amplitude WP, Wave period Wl, Wave increment).

As the current pulse is largely dominated by the stress differences, a short duration current pulse is observed upon loading with a quiescent period during the time at constant stress. With release of pressure upon arrival of the unloading wave from the stress-free surface behind the impactor, a current pulse of opposite polarity is observed. The amplitude of the release wave current pulse provides a sensitive measure of the elastic nonlinearity of the target material at the peak pressure in question. 

For studies in molecular physics, several characteristics of ultrafast laser pulses are of crucial importance. A fundamental consequence of the short duration of femtosecond laser pulses is that they are not truly monochromatic. This is usually considered one of the defining characteristics of laser radiation, but it is only true for laser radiation with pulse durations of a nanosecond (0.000 000 001s, or a million femtoseconds) or longer. Because the duration of a femtosecond pulse is so precisely known, the time-energy uncertainty principle of quantum mechanics imposes an inherent imprecision in its frequency, or colour. Femtosecond pulses must also be coherent, that is the peaks of the waves at different frequencies must come into periodic alignment to construct the overall pulse shape and intensity. The result is that femtosecond laser pulses are built from a range of frequencies the shorter the pulse, the greater the number of frequencies that it supports, and vice versa. 

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