激光和光学纤维为声学提供了巨大的希望。采用一种首先由亚历山大·格雷厄姆·贝尔(Alexander Graham Bell,他因发明电话而享有盛名)所注意到的效应,激光已经使得有可能利用变化的光脉冲投射到液体或固体上来产生声音。光纤可...激光和光学纤维为声学提供了巨大的希望。采用一种首先由亚历山大·格雷厄姆·贝尔(Alexander Graham Bell,他因发明电话而享有盛名)所注意到的效应,激光已经使得有可能利用变化的光脉冲投射到液体或固体上来产生声音。光纤可用来作为声探测器,它的某些优点超过了传统的探测器——压电或声探测器。展开更多
Information on the concentration of suspended sediments in coastal waters is necessary for the understanding and management of the coastal environment. Traditionally, suspended sediment concentration （SSC） has been ...Information on the concentration of suspended sediments in coastal waters is necessary for the understanding and management of the coastal environment. Traditionally, suspended sediment concentration （SSC） has been measured by time-consuming and costly boat surveys which allow the accurate measurement of SSC for single points in space and time. In order to obtain the instantaneous measurement of SSC, a variety of remote sensing method has been adopted. Remote sensing from airborne and spaceborne sensors has been proven to be a useful adjunct to such surveys as it provides an instantaneous and synoptic view of sediments that would otherwise be unavailable. Dominique Durand and Jerome Bijaoui in 2000 presented a feasible study on optical remote sensing of shallow-water environmental parameters. Yogesh C. Agrawal and H. C. Pottsmith in 2001 tried to use Laser Diffraction Sensors to measure Concentration and Size Distribution of Suspended Sediment. Francisco Pedocchi and Marcelo H. Garcia in 2006 made an evaluation of the LISST-ST instrument for suspended particle size distribution and settling velocity measurements. H.K.Ha and W-Y.Hsu in 2009 tried to measure suspended cohesive sediment concentration using ADV backscatter strength. Shuisen Chen, Ligang Fang in 2009 managed to use remote sensing of turbidity in seawater intrusion reaches of Pearl River Estuary. In this article, the brief review of most of the technologies or methods used to observe the suspended sediment concentration is executed. As the most powerful technology in the remote sensing, acoustic backscatter device is discussed in detail. A comparison between those traditional and modern technologies is made to clarify its future application and development.展开更多
The sound ray tracing method can achieve higher accuracy in determining depths and plan positions with multibeam echo sounding system. In data processing, actual sound speed profile must be used in the method. However...The sound ray tracing method can achieve higher accuracy in determining depths and plan positions with multibeam echo sounding system. In data processing, actual sound speed profile must be used in the method. However, the method is too complicated. In order to overcome the shortcoming, this paper presents a new method, the position correction method. Two situations are considered in the new method, namely, change of sound velocity keeps constant gradient in whole water column (including N layers) or in different water layer.展开更多
Bats account for 30% of mammal diversity in SE Asia and are potential bioindicators of wider biodiversity impacts resulting from habitat loss and climate change. As existing sampling techniques in the region typically...Bats account for 30% of mammal diversity in SE Asia and are potential bioindicators of wider biodiversity impacts resulting from habitat loss and climate change. As existing sampling techniques in the region typically fail to record bats that habitually fly in open areas and at higher altitudes, current inventory efforts are less than comprehensive. Acoustic sampling with bat detectors may help to overcome these limitations for insectivorous bats, but has yet to be tested in mainland SE Asia. To do so, we sampled bats while simultaneously recording the echolocation calls of insectivorous species commuting and foraging in a variety of karst habitats in north Vietnam. Monitoring of cave-dwelling bats was also undertaken. Discriminant function analysis of 367 echolocation calls produced by 30 insectivorous species showed that acoustic identification was feasible by correctly classifying 89. 1% of calls. In all habitats, acoustic sampling and capture methods recorded significantly more species each night than capture methods alone. Capture methods consequently failed to record 29% （ten spp. of aerial insectivores） of the bat fauna in commuting and foraging habitats and 11% （two spp. ） of that in our cave sample. Only four of these species were subsequently captured following significantly greater sampling effort. This strongly suggests that acoustic methods are indispensable for maximizing bat inventory completeness in SE Asia. As accurate inventories and monitoring are essential for effective species conservation, we recommend the inclusion of acoustic sampling in future studies of bat assemblages across the region [ Current Zoology 55 （5） ： 327 - 341, 2009].展开更多
A novel self-contained in situ sediment acoustic measurement system based on hydraulic driving penetration is proposed to solve the problem of large disturbances to sediments of the in situ equipments already in exist...A novel self-contained in situ sediment acoustic measurement system based on hydraulic driving penetration is proposed to solve the problem of large disturbances to sediments of the in situ equipments already in existence. By using a hydraulic driving device, the system drives four acoustic probes into sediments at an even speed, and this decreases disturbances to sediments introduced by the penetration of acoustic probes. By means of the special design of the central control unit, the system can work full-automatically and the data are stored self-containedly, and this avoids the requirement of real-time remote controlling from the ship. Its operating water depth, measuring depth and measuring frequency is 500m, 1.0m and 30kHz respectively. A set of in situ sound speeds and attenuation coefficients of sediments are obtained at 40 stations using the system. The results confirm that the data obtained by the in situ sediment acoustic system are accurate and credible.展开更多
Either amplitude based methods or phase based methods are usually used in multibeam bathymetry system and chosen in practical measurement by ad hoc criteria. The errors of the detection are often caused by choosing wr...Either amplitude based methods or phase based methods are usually used in multibeam bathymetry system and chosen in practical measurement by ad hoc criteria. The errors of the detection are often caused by choosing wrong detection method. In this paper a modified multiple subarrays amplitude-phase united detection method is proposed , which uses both the amplitude and phase of echo from bottom.This new method not only realizes the super-wide swath coverage, but also improves the detection performance by using the phase differences among subarrays in place of phases of subarrays to estimate the phase slope image. Experimental results are also analyzed and discussed to demonstrate the effectivity of the proposed approach.展开更多
文摘激光和光学纤维为声学提供了巨大的希望。采用一种首先由亚历山大·格雷厄姆·贝尔(Alexander Graham Bell,他因发明电话而享有盛名)所注意到的效应,激光已经使得有可能利用变化的光脉冲投射到液体或固体上来产生声音。光纤可用来作为声探测器,它的某些优点超过了传统的探测器——压电或声探测器。
基金supported by the National Marine Renewable Energy Program(No.GHME2011ZC03,GHME2010ZC08,GHME 2010ZC11 and GHME2010ZC01)Study of the Key Technology of the Forecast of Global Ocean Circulation and Sea Ice(2011BAC03B02)
文摘Information on the concentration of suspended sediments in coastal waters is necessary for the understanding and management of the coastal environment. Traditionally, suspended sediment concentration （SSC） has been measured by time-consuming and costly boat surveys which allow the accurate measurement of SSC for single points in space and time. In order to obtain the instantaneous measurement of SSC, a variety of remote sensing method has been adopted. Remote sensing from airborne and spaceborne sensors has been proven to be a useful adjunct to such surveys as it provides an instantaneous and synoptic view of sediments that would otherwise be unavailable. Dominique Durand and Jerome Bijaoui in 2000 presented a feasible study on optical remote sensing of shallow-water environmental parameters. Yogesh C. Agrawal and H. C. Pottsmith in 2001 tried to use Laser Diffraction Sensors to measure Concentration and Size Distribution of Suspended Sediment. Francisco Pedocchi and Marcelo H. Garcia in 2006 made an evaluation of the LISST-ST instrument for suspended particle size distribution and settling velocity measurements. H.K.Ha and W-Y.Hsu in 2009 tried to measure suspended cohesive sediment concentration using ADV backscatter strength. Shuisen Chen, Ligang Fang in 2009 managed to use remote sensing of turbidity in seawater intrusion reaches of Pearl River Estuary. In this article, the brief review of most of the technologies or methods used to observe the suspended sediment concentration is executed. As the most powerful technology in the remote sensing, acoustic backscatter device is discussed in detail. A comparison between those traditional and modern technologies is made to clarify its future application and development.
文摘The sound ray tracing method can achieve higher accuracy in determining depths and plan positions with multibeam echo sounding system. In data processing, actual sound speed profile must be used in the method. However, the method is too complicated. In order to overcome the shortcoming, this paper presents a new method, the position correction method. Two situations are considered in the new method, namely, change of sound velocity keeps constant gradient in whole water column (including N layers) or in different water layer.
基金Lam Quang Oanh and Nguyen Tien Dung of Kim Hy Nature Reserve,Nong The Dzien and Bui Van Dinh of Ba Be National Park and Trieu Van Luc of Bac Kan Provincial Forest Protection Department for arranging research permissions(No.317/UBND-NVand631/UBND-NV)
文摘Bats account for 30% of mammal diversity in SE Asia and are potential bioindicators of wider biodiversity impacts resulting from habitat loss and climate change. As existing sampling techniques in the region typically fail to record bats that habitually fly in open areas and at higher altitudes, current inventory efforts are less than comprehensive. Acoustic sampling with bat detectors may help to overcome these limitations for insectivorous bats, but has yet to be tested in mainland SE Asia. To do so, we sampled bats while simultaneously recording the echolocation calls of insectivorous species commuting and foraging in a variety of karst habitats in north Vietnam. Monitoring of cave-dwelling bats was also undertaken. Discriminant function analysis of 367 echolocation calls produced by 30 insectivorous species showed that acoustic identification was feasible by correctly classifying 89. 1% of calls. In all habitats, acoustic sampling and capture methods recorded significantly more species each night than capture methods alone. Capture methods consequently failed to record 29% （ten spp. of aerial insectivores） of the bat fauna in commuting and foraging habitats and 11% （two spp. ） of that in our cave sample. Only four of these species were subsequently captured following significantly greater sampling effort. This strongly suggests that acoustic methods are indispensable for maximizing bat inventory completeness in SE Asia. As accurate inventories and monitoring are essential for effective species conservation, we recommend the inclusion of acoustic sampling in future studies of bat assemblages across the region [ Current Zoology 55 （5） ： 327 - 341, 2009].
文摘A novel self-contained in situ sediment acoustic measurement system based on hydraulic driving penetration is proposed to solve the problem of large disturbances to sediments of the in situ equipments already in existence. By using a hydraulic driving device, the system drives four acoustic probes into sediments at an even speed, and this decreases disturbances to sediments introduced by the penetration of acoustic probes. By means of the special design of the central control unit, the system can work full-automatically and the data are stored self-containedly, and this avoids the requirement of real-time remote controlling from the ship. Its operating water depth, measuring depth and measuring frequency is 500m, 1.0m and 30kHz respectively. A set of in situ sound speeds and attenuation coefficients of sediments are obtained at 40 stations using the system. The results confirm that the data obtained by the in situ sediment acoustic system are accurate and credible.
基金Sponsored by Foundation of Underwater Acous-tic Technology National Key Lab(No.51445030205ZS2301) Foundation of the Chinese Postdoctoral Science ( No.LRB00025).
文摘Either amplitude based methods or phase based methods are usually used in multibeam bathymetry system and chosen in practical measurement by ad hoc criteria. The errors of the detection are often caused by choosing wrong detection method. In this paper a modified multiple subarrays amplitude-phase united detection method is proposed , which uses both the amplitude and phase of echo from bottom.This new method not only realizes the super-wide swath coverage, but also improves the detection performance by using the phase differences among subarrays in place of phases of subarrays to estimate the phase slope image. Experimental results are also analyzed and discussed to demonstrate the effectivity of the proposed approach.
