Colleagues,
The Washington D.C. Chapter of the Acoustical Society of America is pleased to announce the first meeting of 2003! Please plan to attend the meeting and enjoy an evening of presentations on acoustics.
When:
June 3rd, 2003
7:00-9:00 PM
Where:
Catholic University Of America
620 Michigan Ave. N.E.
Washington, D.C. 20064
School Of Engineering
Pangborn Hall, Scullen Room, 1st Floor
Driving Directions:
http://publicaffairs.cua.edu/direct.htm
Metro:
http://www.cua.edu/centers/metromap.cfm
Attendance is free. Please RSVP by COB 30th of May 2003 to ASAchapterDC@yahoo.com if you plan to attend the meeting.
Please join us!
Jerry Dietz
Secretary, DC ASA Chapter
http://www.geocities.com/ASAchapterDC
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Speaker #1: Dr. Harry Cox
Title: Interference Patterns in Range Dependant Environments
Abstract: Interference patterns in space and frequency occur in ocean acoustics due to coherent multi-path propagation. The wave guide invariant beta is commonly used to describe the behavior of these patterns.[Brikhosvsky and Lysanov, Fundamentals of Ocean Acoustics, 1991 2nd Ed. Springer-Verlag] The standard derivation of this invariant uses a normal mode expansion and is limited to range independent and weakly range dependent environments. A different approach is introduced that describes the interfering components in terms of their travel times. This leads to a very simple derivation of basic results that apply equally well to range dependent environments and to situations, such as Lloyd's Mirror, in which the normal mode representation is inconvenient. Beta can be expressed in terms of the local phase velocities and the difference in travel times for the interfering components. The travel time differences involve integration over the entire path trajectories from the source to the point where the interference pattern is observed. Numerical examples using ray theory will be presented.
Resume: Dr. Cox has over 30 years of experience in the application of advanced signal processing technology to problems of national defense. He is an authority on antisubmarine warfare, and a recognized technical expert in signal processing, antenna arrays, underwater acoustics, and sonar system design and analysis. He currently serves on several Navy senior technical panels and advisory groups. He is an experienced manager of highly successful projects. He has also applied this experience to problems in medical electronics, including automated EEG data analysis and classification of ultrasound echoes. He has been the technical leader of several projects that employed neural networks and expert systems to automatically classify signals in a variety of applications. His recent contributions include development of algorithms for robust adaptive beamforming, development of simplified techniques for matched field processing, pioneering work in bistatic active sonar, new processing methods for Doppler exploitation in active sonar, and for passive ranging, and development of system approaches for passive distributed systems and shallow-water active sonar.
From 1981 to 1991, he was a Vice President of BBN. During his distinguished carrier as a naval officer, he held a number of important R&D positions, retiring as Captain USN in 1981. He was the Project Manager for the Undersea Surveillance Project, Division Director at DARPA, and Officer in Charge of the New London Laboratory of the Naval Underwater Systems Center. Dr. Cox is the author of more than 50 technical papers. He is a fellow of both the Institute of Electrical and Electronics Engineering and the Acoustical Society of America. He was awarded the Gold Medal of the American Society of Naval Engineers. In 1991 he received the Distinguished Technical Achievement Award of the Ocean Engineering Society. He was elected to the National Academy of Engineering in 2002.
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Speaker #2: Dr. Jay Pulli
Title: The International Monitoring System of The Comprehensive Nuclear Test Ban Treaty: An Overview with a Focus on Acoustics
Abstract: The Comprehensive Nuclear Test Ban Treaty was adopted by the United Nations on September 10, 1996. The treaty bans all nuclear weapons testing by its member countries. Statistics of signature and ratification include:
> 165 countries have signed the treaty.
> Ninety countries have ratified it.
> Thirty-one of the required forty-four countries with nuclear capability have ratified the CTBT.
> The United States has signed but not ratified the Comprehensive Nuclear Test Ban Treaty
Once the Comprehensive Nuclear Test Ban treaty enters into force, there will need to be a system in place to verify treaty compliance. Research and development of this system has been underway since the early nineties. The International Monitoring System (IMS) will be a continuously active system that will be able to detect and localize a nuclear explosion anywhere on the globe. It will include seismic sensors, hydroacoustic sensors, infrasound sensors and radionuclide sensors.
This presentation will give a brief overview of the Treaty and the International Monitoring System (IMS). It will then focus on the current research in the acoustics-related areas of the IMS. Global hydroacoustic and atmospheric infrasound theory, modeling, simulation and signal processing will be discussed.
Resume: Dr. Jay Pulli is a Division Scientist at BBN Technologies. Dr. Pulli received his Ph.D. in Geophysics from Massachusetts Institute of Technology. He has over 27 years experience in seismology, acoustics and computer modeling, including 17 years of direct involvement with CTBT monitoring research. While at BBN he has conducted research on long-range hydroacoustic reflections recorded for underwater explosions and how they could be utilized to enhance the hydroacoustic component of CTBT monitoring; performed research on the passive seismic and acoustic identification of underground facilities; served on the Panel of Geophysical Experts for the IAEA/NRC study of geophysical techniques for safeguarding geological repositories; conducted research and field testing of the use of imploding glass spheres as deep-water acoustical sources for CTBT hydroacoustic calibration; and performed research and field experiments on the seismic detection and classification of shallow unexploded ordnance (UXO). Prior to BBN, he has conducted research on seismic discrimination, neural networks, adaptive signal processing, and earthquake risk assessment. He is the author or co-author of over 45 published papers and reports on these subjects.