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

通过对横滨国立大学长实验槽内产生的人工短峰不规则波进行测量，对海浪定向谱实用测量系统进行了开发研究。新研制的多分段波发生器精确地给出了短峰不规则波的定向谱。因此，一个新的完整的系统，具有以下特点。提出了一种利用水下垂直发射的激光束探测多点波的新方法。波面上的激光光斑由电视摄像机从对角线向上拍摄，并由录像机记录下来。对录制的视频进行处理、数字读出，并通过数字计算转换为多点的地表高程。这种新型激光测波仪具有非接触式测量、高精度、高频响应高、体积小等优点。利用高速绘图仪打印机的个人计算机系统在短时间内完成定向光谱分析。在波频和波向的精细分辨率下，采用最大似然法计算方向谱。在测量点，几乎可以实时得到所测方向谱的各种图形的硬拷贝。通过这种新型测量系统的研制，为实际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.