應用聲學及光學儀器在均勻及現場懸浮質濃度之量測率定及比較;Calibration and comparison of suspended sediment concentration measurement for uniform and non-uniform particles using acoustic and optical sensors

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Title:	應用聲學及光學儀器在均勻及現場懸浮質濃度之量測率定及比較;Calibration and comparison of suspended sediment concentration measurement for uniform and non-uniform particles using acoustic and optical sensors
Authors:	邱鈺宸;Chiou,Yu-Chen
Contributors:	水文與海洋科學研究所
Keywords:	懸浮微粒濃度;光學濁度儀（OBS）;都卜勒聲學流速儀（ADVO）;儀器率定;均質微粒;非均質微粒;suspended sediment concentration;Optical Backscatter Sensor;Acoustic Doppler Velocimeter;sensor calibration;uniform particles;non-uniform particles
Date:	2015-01-26
Issue Date:	2015-03-16 15:11:40 (UTC+8)
Publisher:	國立中央大學
Abstract:	本研究旨在探討運用都卜勒聲學流速儀（ADVO）及光學濁度儀（OBS）來測量不同特性懸浮沉積物的差異性，並與前人研究結果進行比較討論。當已知訊號傳遞至不同濃度的懸浮微粒時，因濃度的改變而產生不同強度的反射訊號，故擬應用此原理來探討懸浮沉積物濃度與反射訊號強度的關係。為了能在濃度均勻且無氣泡影響的量測環境下進行濃度率定實驗，本研究排除影響儀器接收反射訊號干擾的因子，使儀器率定結果精準度增加。本研究建立一個新的率定水槽，並對此水槽進行空間均勻度、實驗再現性等多種驗證。經過改善後，測試結果顯示此新建立的水槽及實驗方法可以作為懸浮物濃度的率定用水槽及標準化。文中分別使用細顆粒均質玻璃珠及現場所採集到的底部表層底沙作為懸浮微粒來進行儀器濃度率定實驗。將光學濁度儀對玻璃珠及現場底沙率定曲線進行比較，結果顯示在特定濃度內，量測值會與均質懸浮微粒濃度呈現線性關係，超過此濃度後，率定曲線會呈現非線性情況。另外研究證實，於特定濃度範圍內，聲學都卜勒流速儀所接收的反射訊號強度會與水體內懸浮微粒濃度呈線性關係，顯示聲學都卜勒流速儀未來應可成為量測現場懸浮沉積物濃度變化的儀器。本研究將實驗結果與Ha et al.[2009]的結果進行比較，發現在均質及現場懸浮質的量測環境下，聲學都卜勒流速儀的率定曲線趨勢有相似的變化。 ;The study aims to investigate the suspended sediment concentration (SSC) for uniform and non-uniform particles using Acoustic Doppler Velocimeter Ocean（ADVO）and Optical Backscatter Sensor（OBS）. Because the backscatter intensity of the transmitted signals from the acoustic and optical sensors varies depending on the SSC in the water, it is possible to find an empirical correlation function between the measured backscatter intensity and the SSC. Because air bubbles and non-uniform distributed SSC in the water can affect the calibration results, we try to exclude these factors in advance to increase the calibration accuracy. We developed a new calibration tank and perform the verification of spatial uniformity, and experimental repeatability. The results show that the calibration tank and the experimental methods can be used to calibrate the SSC. In this study, artificial uniform glass particles and non-uniform sediment particles sampled from the field over an algal reef are used for calibration. The calibration curves of the optical sensor for the uniform glass particles and field sediment particles are compared; it is found that the backscatter intensity shows a linear trend with the SSC within a specific range of SSC, and then the gradient between the SSC and backscatter decreases when the SSC exceeds the specific value. In addition, the study confirms the linear relationship between the acoustic backscatter intensity and the SSC for a specific SSC which indicating that ADVO could be used to measure the change of SSC in fields. Finally, we compared the results with Ha at el. [2009], and found that the trends of the calibration curves of the ADVs are similar to their results even though different sediment particles are used in the two experiments.
Appears in Collections:	[Graduate Institute of Hydrological and Oceanic Sciences] Electronic Thesis & Dissertation

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