| dc.description.abstract | In this paper, the team of National Central University and ＂DRIFTER TECHNOLOGY CO., LTD.＂ jointly developed a fully solid state micro data buoys, called ＂Miniature Wave Buoys (MWBs)＂, using MEMS (Micro Electro Mechanical Systems) as the main measurement system of inertial sensing, and the main measurement items include wind speed and direction and wave related sea surface parameters. It is the first research method in the world that uses buoys to calculate Mean Square Slope (MSS) and invert the wind speed.
The above two observation projects were analyzed in a large cross-sectional flume at National Cheng Kung University, divided into time series and spectrum analysis experiments to verify the feasibility. The experimental method used a series of wave generation experiments and rigorous data quality control analysis to correct the water surface inclination and wave parameters before applying them to field measurements. In order to increase the survival rate of the instrument, the MWBs are now miniaturized and the exposed anemometer used for wind speed and direction measurement has been removed. The MWBs used in this study can be used to observe wind speed, wind direction and waves. The observation principle and algorithm can be divided into: (A) The inertial sensing system measures the inclination value and calculates the MSS (Mean Square Slope) as the wind speed parameter based on the inclination spectrum, and then performs wind speed and wind direction analysis. (B) The inertial sensing system measures the vertical acceleration value, calculates the acceleration spectrum, and converts the water level spectrum by the transfer function to perform the wave analysis.
The above two observation projects were analyzed in a large cross-sectional flume at National Cheng Kung University (NCKU), divided into time series and spectrum analysis experiments to verify the feasibility. The experimental method used a series of wave generation experiments and rigorous data quality control analysis to correct the water surface inclination and wave parameters before applying them to field measurements.
In the water tank experiment, it was found that the average relative error of the time series was about 5.6% when the inclination angle of the water surface was less than 15°, and the average relative error increased rapidly to about 9.4% after the inclination angle of the water surface exceeded 15°. In addition, the transmission coefficient between the two instruments can be observed in the frequency domain, and when the ratio of the two measurements is one, it can be used as a compensation coefficient. The results of the wave comparison between the microdata buoy wave height and period were 0.038m and 0.363s, respectively, by quantitative analysis of the wave parameters corrected by the transfer function.
The field measurement mainly collects Mean Square Slope (MSS), indicative wave height, mean period, etc., and uses MSS as the basis for wind speed calculation, and at the same time uses its own calibrated instrument for cross-checking to obtain the feasibility of actual buoy measurement. The MSS algorithm was corrected by the data quality control and the high-frequency slope of the wave spectrum, and the observed MSS values and their correlation with the wind speed were consistent with the literature, indicating that the MSS observation of the microdata buoy can be applied to the observation of the wind speed at the sea surface and the error of wind speed estimation can be further reduced by using the wave age parameter. The results of the wind speed measurement from the central meteorological office have a root mean square error of about 2.39m/s.
At present, when the micro data buoy is applied to field experiments, it is found that the buoy is easily limited by the rope tension of the mooring line, and when abnormal waves or broken waves occur, the overall mass of the buoy is small and produces a large jump out of the water, which causes deviations in the observation results. | en_US |