Wave power

About: Wave power is a research topic. Over the lifetime, 2671 publications have been published within this topic receiving 41439 citations. The topic is also known as: wind wave energy & sea wave energy.

Radio wave arrival direction estimating device and directional variable transmitter-receiver

Abstract: PROBLEM TO BE SOLVED: To precisely estimate the principal wave direction of an arrival wave having high correlation. SOLUTION: An arrival wave number determination part 10 calculates a ratio Er between a maximum value and the next maxim value of a characteristic value of a covariance matrix R of a M-element array reception signal so as to compare it with a predetermined value Dr. When he ratio Er is not less than the predetermined value Dr, the number of arrival waves is determined to be one, while the number of incoming waves is determined to be M-1 when the ratio Er is less than the value Dr. A virtual linear array conversion part 12 converts reception signals ranging from 2-1 to 2-M of a circular array into virtual linear array reception signals. An arrival wave power estimation part 13 estimates arrival wave power at an angular interval Δθ. An arrival direction estimation part 11 computes an incoming direction estimation function F(θ) at an angular interval Δθ while using a matrix ES consisting of S eigenvectors in the covariance matrix R as a signal characteristic spatial matrix and using a matrix EN consisting of (M-S) eigenvectors as a noise characteristic spatial matrix if the incoming wave number determination in the incoming wave number determination part results in an S-wave. A principal wave direction estimation part 14 combines the computed value F(θ) in the arrival direction estimation part 11 and the computed value in the incoming wave power estimation part 13 together so as to determine its maximum value direction as the principal wave direction estimation result.

The sampling variability and the validation of high frequency radar measurements of the sea surface

Abstract: Remote sensing is becoming an increasingly important tool for ocean wave measurement, and over the past decade much progress has been made in the development of the wave measuring capabilities of HF (High Frequency) radar. This system is able to make detailed and near continuous observations of the sea surface over a wide area. However, because the mathematics of the data extraction process is rather difficult, the statistical properties of the observed data have to date been poorly understood. In this study, the approximate sampling distributions of a variety of measurements from HF radar (including significant waveheight, mean wave period, wind direction, and various spectral parameters) are derived in terms of quantities that are either known or estimable. The resulting confidence intervals are, in the case of significant waveheight and mean wave period, of comparable width to those obtained from the corresponding NURWEC2 (Netherlands UK Radar Wave buoy Experimental Comparison) wave buoy measurements, and in the case of spectral power, they are narrower. Furthermore, methods are derived by which such radar measurements may be compared with their corresponding wave buoy measurements in a statistically valid manner, and their relative biases estimated. These methods are then applied to data taken during the NURWEC2 field trial, which suggest that the radars and the wave buoy show good correspondence for measurements of significant waveheight and of spectral power (over 85 - 125mHz - the frequencies with most wave power, and hence those of most importance). There is also a fair correspondence for mean period measurements in the range 6.8 - 11.0secs. Spectral mean direction shows good correspondence over 85 - 155mHz over the somewhat limited directional range (i. e. as observed during the NURWEC2 storm) of the data.

Gravity type foundation for off-shore wind power generation device

Abstract: PROBLEM TO BE SOLVED: To install an off-shore wind power generation device in open-sea where the off-shore wind power generation device can show great power generation capacity by enabling the off-shore wind power generation device to be installed with relatively low capacity caisson, minimizing construction time on sea, making acting wave power small, and making slide resistance force large in a gravity type foundation for the off-shore wind power generation device using the caisson. SOLUTION: The pre-cast gravity type caisson 3 manufactured beforehand in an on-shore yard or the like is composed of a round bottom plate 4, a cylindrical lower part side wall 5 rising as one unit from an outer circumference part of the bottom plate 4, an upper side wall 6 of a small diameter cylinder shape, and a truncated conical taper side wall 7 connecting the lower part side wall 5 and the upper part side wall 6 as one unit. Acting wave power is made small by making area to be resistance close to still water level and using a cylindrical surface on which wave power acting is small, and sliding resistance force of the caisson 3 is made large by making friction resistance large by a friction increase mat 8 on a caisson bottom surface, increasing grounding force by using high specific gravity material 9 as a material filled in. COPYRIGHT: (C)2007,JPO&INPIT