Multiple-source localization using GPS technology and receivedarrival time structure analysis in an air-deployed system     

Stotts  S.A. Martin  J.L. Bedford  N.R. 《Oceanic Engineering, IEEE Journal of》1997,22(3):576-582

An efficient and robust method has been developed to locate multiple impulsive sources in an ocean environment. Global position system (GPS) receivers were installed on sonobuoys to obtain their locations within a few meters of accuracy. A sonobuoy field was deployed in a ring-type pattern. Charges were then set off at arbitrary locations within the ring, High-resolution plots were used to obtain direct path and/or first bottom bounce arrivals on each buoy. A model grid of arrival times was constructed, corresponding to the dimensions of the buoy field. A ray model previously developed here at the Applied Research Laboratories at the University of Texas at Austin (ARL:UT) was used to obtain model travel times. The minimum value of the least-square-type error between the real arrival times and the modeled travel times resulted in an unambiguous location of the source, within the limits of the grid spacing chosen. This value was calculated by picking one receiver as the reference and then summing the timing errors of the remaining receivers relative to the reference. Successive iterations with finer grid spacings result in source localization within the accuracy of the buoy locations. The localization routine was extended by allowing permutations of the pulse arrivals on each buoy to account for multiple sources closely separated in time and/or space. An automated correlation technique is presented as an alternative to the leading edge-detection method used here for obtaining relative arrival times. Two proof-of-concept experiments were performed and some results of data obtained at Lake Travis and the Gulf of Mexico are presented  相似文献   

Geoacoustic Inversions of Horizontal and Vertical Line Array Acoustic Data From a Surface Ship Source of Opportunity     

Stotts  S. A Koch  R. A. Joshi  S. M. Nguyen  V. T. Ferreri  V. W. Knobles  D. P. 《Oceanic Engineering, IEEE Journal of》2010,35(1):79-102

The application of an inversion methodology produces the first demonstration of a simultaneous solution for geoacoustic and source track parameters from acoustic data collected in a shallow-water, sandy sediment environment. Inversion solutions from data collected in the 2006 Shallow Water Experiment (SW06) are extracted from noise measurements of a surface ship source on an L-array. The methodology includes a screening algorithm to determine a set of frequencies for the inversion data. In addition, the methodology assesses the accuracy of the inversion solution and incorporates an estimation of parameter value uncertainties. The solution from the inversion of the horizontal component of the L-array data from the surface ship source before its closest point of approach (CPA) is used to construct modeled propagation loss for comparison with observed received level (RL) structure as the source departs from CPA. Inversion of the data from a single element in the vertical component of the L-array produces a solution that agrees with the solution obtained from the inversion of horizontal subaperture data. Also, modeled transmission loss (TL) structure obtained from the single-element inversion solution reproduces the depth dependence of the RL structure observed at other elements of the vertical component of the L-array.   相似文献   

Changes in submerged aquatic macrophyte populations at the head of Chesapeake Bay, 1958–1975     

Suzanne Bayley  Vernon D. Stotts  Paul F. Springer  John Steenis 《Estuaries and Coasts》1978,1(3):171-182

Submerged aquatic plant populations in the Susquehanna Flats of the Chesapeake Bay were followed for 18 years. An exotic species, eurasian water milfoil,Myriophyllum spicatum, increased dramatically from 1958 to 1962; at the same time the dominant native species declined. After 1962, milfoil populations declined and the native rooted aquatics gradually began to return to their former levels. In the late 1960's all species declined and in 1972 almost disappeared from the Susquehanna Flats. These fluctuations may have been related to several interrelated environmental factors in the Chesapeake Bay, including tropical storms, turbidity, salinity and disease. The utilization of the Susquehanna Flats by waterfowl appears to be related to the abundance and species composition of the submerged macrophytes present.  相似文献   

Numerical study of geoacoustic inversion in range-dependent ocean environments     

Knobles  D.P. Koch  R.A. Stotts  S.A. Neilsen  T.B. 《Oceanic Engineering, IEEE Journal of》2003,28(3):355-369

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