Download or read book Range dependent Matched Field Source Localization and Tracking in Shallow Water on a Continental Slope Region of the North East Pacific Ocean written by Martin Luc Taillefer and published by . This book was released on 1998 with total page 228 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Master s Theses Directories written by and published by . This book was released on 1999 with total page 492 pages. Available in PDF, EPUB and Kindle. Book excerpt: "Education, arts and social sciences, natural and technical sciences in the United States and Canada".
Download or read book Source Detection and Localization Performance of Matched Field Processors in a Real and Uncertain Shallow Water Ocean Environment written by Katherine Haekyung Kim and published by . This book was released on 2002 with total page 518 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Range dependent Passive Source Localization Using Data from the Barents Sea Tomography Experiment written by David D. Pierce and published by . This book was released on 1996 with total page 84 pages. Available in PDF, EPUB and Kindle. Book excerpt: Matched-Field Processing (MFP) and Matched-Mode Processing (MMP) are two popular techniques for passively localizing an underwater acoustic emitter in range and depth. One major drawback of these techniques has been their sensitivity to uncertainty concerning the acoustic environment. Several methods for addressing this phenomenon have been proposed in the literature, with varying degrees of success. Achieving high-quality location estimates remains a problem except in simple range-independent experiments or numerical simulations. In this study, we demonstrate an approach for robust, accurate emitter localization in a highly range-dependent real environment using MMP. The main factors contributing to successful localization are: 1) use of the high-resolution Multiple Signal Classification (MUSIC) algorithm, which performs well even when only a few robust modes can be obtained by mode filtering; and 2) use of an acoustic propagation model incorporating mode coupling, which is able to generate accurate replica fields in a strongly range-dependent environment. A secondary objective of the study was to demonstrate the application of higher-order statistical estimation techniques to reduce noise effects. Our results indicate that these techniques show unacceptable sensitivity to noise- and model-induced estimation errors and require further refinement before they will be useful in the underwater acoustic localization problem.
Download or read book Springer Handbook of Acoustics written by Thomas Rossing and published by Springer Science & Business Media. This book was released on 2007-06-21 with total page 1179 pages. Available in PDF, EPUB and Kindle. Book excerpt: This is an unparalleled modern handbook reflecting the richly interdisciplinary nature of acoustics edited by an acknowledged master in the field. The handbook reviews the most important areas of the subject, with emphasis on current research. The authors of the various chapters are all experts in their fields. Each chapter is richly illustrated with figures and tables. The latest research and applications are incorporated throughout, including computer recognition and synthesis of speech, physiological acoustics, diagnostic imaging and therapeutic applications and acoustical oceanography. An accompanying CD-ROM contains audio and video files.
Download or read book Performance Bounds on Matched Field Methods for Source Localization and Estimation of Ocean Environmental Parameters written by and published by . This book was released on 2001 with total page 219 pages. Available in PDF, EPUB and Kindle. Book excerpt: Matched-field methods concern estimation of source location and/or ocean environmental parameters by exploiting full wave modeling of acoustic waveguide propagation. Typical estimation performance demonstrates two fundamental limitations. First, sidelobe ambiguities dominate the estimation at low signal-to-noise ratio (SNR), leading to a threshold performance behavior. Second, most matched-field algorithms show a strong sensitivity to environmental/system mismatch, introducing some biased estimates at high SNR. In this thesis, a quantitative approach for ambiguity analysis is developed so that different mainlobe and sidelobe error contributions can be compared at different SNR levels. Two large-error performance bounds, the Weiss-Weinstein bound (WWB) and Ziv-Zakai bound (ZZB), are derived for the attainable accuracy of matched-field methods. To include mismatch effects, a modified version of the ZZB is proposed. Performance analyses are implemented for source localization under a typical shallow water environment chosen from the Shallow Water Evaluation Cell Experiments (SWellEX). The performance predictions describe the simulations of the maximum likelihood estimator (MLE) well, including the mean square error in all SNR regions as well as the bias at high SNR. The threshold SNR and bias predictions are also verified by the SWellEX experimental data processing. These developments provide tools to better understand some fundamental behaviors in matched-field performance and provide benchmarks to which various ad hoc algorithms can be compared.
Download or read book Matched Field Processing in Shallow Water Using a Small Aperture Horizontal Line Array written by Robert S. Veenhuis and published by . This book was released on 1994 with total page 81 pages. Available in PDF, EPUB and Kindle. Book excerpt: Matched Field Processing (MFP) is a beamforming technique which allows for the detection and localization of an acoustic source in range and depth using passive sonar. The performance of MFP in shallow water environments using a short aperture horizontal line array is investigated. Shallow water test cases are utilized to evaluate the effects of frequency, bottom type, relative target bearing, and sound speed profile on MFP performance. Data from RANGEX 1- 92 is also utilized to test the performance of the eight nearest neighbor peak picker (ENNPP) and M of N tracker for a horizontal line array in a real ocean environment. It is shown that MFP performance is significantly better for higher frequencies, for more reflective, bottom types, and for relative target bearings away from the broadside beams. lt is also shown that the performance of plane wave beamformers is severely degraded in shallow water for relative bearings away from the broadside beams, particularly at higher frequencies. Finally, the MFP algorithm in conjunction with the ENNPP and M of N tracker are shown to perform well in the real ocean environment.
Download or read book Matched Field Processing in Shallow Water Using a Small Aperture Horizontal Line Array written by Robert S. Veenhuis and published by . This book was released on 1994 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Matched Field Processing (MFP) is a beamforming technique which allows for the detection and localization of an acoustic source in range and depth using passive sonar. The performance of MFP in shallow water environments using a short aperture horizontal line array is investigated. Shallow water test cases are utilized to evaluate the effects of frequency, bottom type, relative target bearing, and sound speed profile on MFP performance. Data from RANGEX 1- 92 is also utilized to test the performance of the eight nearest neighbor peak picker (ENNPP) and M of N tracker for a horizontal line array in a real ocean environment. It is shown that MFP performance is significantly better for higher frequencies, for more reflective, bottom types, and for relative target bearings away from the broadside beams. lt is also shown that the performance of plane wave beamformers is severely degraded in shallow water for relative bearings away from the broadside beams, particularly at higher frequencies. Finally, the MFP algorithm in conjunction with the ENNPP and M of N tracker are shown to perform well in the real ocean environment.
Download or read book Broadband Matched field Source Localization in the East China Sea written by and published by . This book was released on 2002 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Presentation of broadband matched-field source localization in the East China Sea.
Download or read book Dissertation Abstracts International written by and published by . This book was released on 2006 with total page 942 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Ocean Noise and Marine Mammals written by National Research Council and published by National Academies Press. This book was released on 2003-05-22 with total page 220 pages. Available in PDF, EPUB and Kindle. Book excerpt: For the 119 species of marine mammals, as well as for some other aquatic animals, sound is the primary means of learning about the environment and of communicating, navigating, and foraging. The possibility that human-generated noise could harm marine mammals or significantly interfere with their normal activities is an issue of increasing concern. Noise and its potential impacts have been regulated since the passage of the Marine Mammal Protection Act of 1972. Public awareness of the issue escalated in 1990s when researchers began using high-intensity sound to measure ocean climate changes. More recently, the stranding of beaked whales in proximity to Navy sonar use has again put the issue in the spotlight. Ocean Noise and Marine Mammals reviews sources of noise in the ocean environment, what is known of the responses of marine mammals to acoustic disturbance, and what models exist for describing ocean noise and marine mammal responses. Recommendations are made for future data gathering efforts, studies of marine mammal behavior and physiology, and modeling efforts necessary to determine what the long- and short-term impacts of ocean noise on marine mammals.
Download or read book Threshold Region Performance Prediction for Adaptive Matched Field Processing Localization written by and published by . This book was released on 2004 with total page 11 pages. Available in PDF, EPUB and Kindle. Book excerpt: Matched field processing (MFP) provides a means of attaining the full gains available from the shallow-water acoustic channel in passive sonar signal processing. By modeling the full field structure of acoustic signals propagating in the ocean MFP offers the potential for both detection gain (through its better signal model) and localization gain (through its additional discrimination capability in range and depth) over traditional planewave processing. However, high spatial ambiguities and mismatch present formidable challenges in practice limiting the performance gains that are realistically achievable with MFP. Prediction of MFP localization performance is a challenging problem. MFP replica (steering) vectors can be highly ambiguous in range and depth resulting in significant non-local estimation errors at low signal-to-noise ratios (SNRs)-errors not modeled by traditional localization measures such as the Cramer-Rao bound. Recent work has demonstrated the accuracy of an interval-error-based method referred to herein as the "method of interval errors" (MIE), in predicting mean- squared error localization performance well into the threshold region where non-local errors may dominate. This work uses the MIE to predict the mean-squared error accuracy of MFP range and depth estimates for two well-known approaches: (i) conventional beamforming (equivalent to maximum likelihood estimation for white noise) and (ii) Capon-MVDR adaptive beamforming. Simulation results will characterize localization performance as a function of SNR, for apertures and environments of interest. Particular attention will be given to the "threshold SNR" (below which localization performance degrades rapidly due to global estimation errors) and to the minimum SNR required to achieve acceptable range/depth localization. Initial work will also be presented assessing the MIE's potential to characterize localization performance in the presence of mismatch.
Download or read book Source Localization in Shallow Water Using Multi frequency Processing of Shot Data written by G. Haralabus and published by . This book was released on 1996 with total page 24 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Short Range Souce Tracking in an Uncertain Shallow Water Environment written by Stacy L. Tantum and published by . This book was released on 1996 with total page 102 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Source Signature Estimation and Noise Directionality in Shallow Water written by and published by . This book was released on 1995 with total page 7 pages. Available in PDF, EPUB and Kindle. Book excerpt: Two experiments were carried out in August-September 1993 in a shallow water test bed region off the coast of southern California. SWellEx-1 (Shallow Water evaluation cell Experiment #1), was carried out in August 1993 west of Point Loma in approximately 200 m water. SWellEx-2 (also known as the Site Specific Experiment or SSE) was carried out in September 1993 adjacent to San Clemente island in both 450 m and 1200 m water. During both of these experiments, along-slope and cross-slope controlled source tow events were carried out for the purpose of validating predictions made by full-wave propagation models as well as to carry out an initial look at matched-field processing in shallow water. In addition, several days of ambient noise data were collected during these experiments providing an opportunity to look at the time-evolving characteristics of ambient noise horizontal and vertical directionality in shallow water. As expected, shipping noise varied substantially due to fluctuations in traffic patterns. The contribution of biologics to the noise background (at night) was surprisingly large.
Download or read book The Ocean and Cryosphere in a Changing Climate written by Intergovernmental Panel on Climate Change (IPCC) and published by Cambridge University Press. This book was released on 2022-04-30 with total page 755 pages. Available in PDF, EPUB and Kindle. Book excerpt: The Intergovernmental Panel on Climate Change (IPCC) is the leading international body for assessing the science related to climate change. It provides policymakers with regular assessments of the scientific basis of human-induced climate change, its impacts and future risks, and options for adaptation and mitigation. This IPCC Special Report on the Ocean and Cryosphere in a Changing Climate is the most comprehensive and up-to-date assessment of the observed and projected changes to the ocean and cryosphere and their associated impacts and risks, with a focus on resilience, risk management response options, and adaptation measures, considering both their potential and limitations. It brings together knowledge on physical and biogeochemical changes, the interplay with ecosystem changes, and the implications for human communities. It serves policymakers, decision makers, stakeholders, and all interested parties with unbiased, up-to-date, policy-relevant information. This title is also available as Open Access on Cambridge Core.
Download or read book Global Trends 2040 written by National Intelligence Council and published by Cosimo Reports. This book was released on 2021-03 with total page 158 pages. Available in PDF, EPUB and Kindle. Book excerpt: "The ongoing COVID-19 pandemic marks the most significant, singular global disruption since World War II, with health, economic, political, and security implications that will ripple for years to come." -Global Trends 2040 (2021) Global Trends 2040-A More Contested World (2021), released by the US National Intelligence Council, is the latest report in its series of reports starting in 1997 about megatrends and the world's future. This report, strongly influenced by the COVID-19 pandemic, paints a bleak picture of the future and describes a contested, fragmented and turbulent world. It specifically discusses the four main trends that will shape tomorrow's world: - Demographics-by 2040, 1.4 billion people will be added mostly in Africa and South Asia. - Economics-increased government debt and concentrated economic power will escalate problems for the poor and middleclass. - Climate-a hotter world will increase water, food, and health insecurity. - Technology-the emergence of new technologies could both solve and cause problems for human life. Students of trends, policymakers, entrepreneurs, academics, journalists and anyone eager for a glimpse into the next decades, will find this report, with colored graphs, essential reading.
