Development on the Practical Measuring System of Directional Spectra of Ocean Waves.

通过对横滨国立大学长实验水池中人工产生的短峰不规则波的测量，对海浪方向谱实用测量系统进行了开发性研究。新研制的多段式造波机能精确地给出短峰不规则波的方向谱，从而形成一套完整的新系统，具有以下特点.研制了一种利用水下垂直发射激光束进行多点测波的新型测波仪。用电视摄像机从斜上方拍摄波面上的激光光斑，用录像机记录。对记录的视频进行处理，数字读出，通过数字计算转换成多点的表面高程，这种新型激光测头具有非接触测量、精度高、频响高、体积小等优点.方向谱的分析是由个人计算机系统与高速喷墨打印机在短时间内完成的。在波的频率和方向的精细分辨率下，采用最大似然法计算方向谱。在该测量地点，几乎可以真实的实时得到被测方向谱的各种图形的硬拷贝.通过该系统的研制，为实际的海洋测量提供了一种新的测量系统。

A developmental research on the practical measuring system of directional spectra of ocean waves was carried out by measurement of the artificial short crested irregular waves generated in the long experimental tank of Yokohama National University. Those short crested irregular waves were exactly given the specified directional spectra by the newly developed multi segmented wave generator.Consequently a new complete system which has following specialties was developed.1. A new wave probe for multi points using laser beams that projected vertically from underwater was invented. Laser spots on the wave surface are taken by a TV camera from diagonally upward direction and recorded by the video tape recorder. Recorded video is processed, read out by digital and converted to surface elevation of multi points by the digital calculation.This new laser wave probe has great merits, viz. non contact measurement,highprecision,high frequency response,small size etc.2. Analysis of directional spectra is Performed in short time by the personal computer system with high speed plotter printers. Directional spectra are calculated by the adaptation of the maximum likclihood method under the fine resolution of wave frequency and direction. Hard copies of various figures of the measured directional spectra can get in almost real time at that measuring place.3. It is not so difficult to make a new measuring system for actual ocean by the development of this new system.