| Supplemental Student Support: Detection and Identification of Buried Targets using Time Reversal Acoustics |
04-Nov-2009 |
283 pages |
| Authors:
Ronald A Roy; Zachary J Walters; BOSTON UNIV MA
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 | The presence of noise and coherent returns from clutter often confounds efforts to acoustically detect and identify target objects buried in inhomogeneous media. Using iterative time reversal with a single channel transducer, returns from resonant targets are enhanced, yielding convergence to a narrowband waveform characteristic of the dominant mode in a target's elastic scattering response. The procedure consists of exciting the target with a broadband acoustic pulse, sampling the return ... |
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| 3D Modeling of Iran and Surrounding Areas from Simultaneous Inversion of Multiple Geophysical Datasets |
30-Sep-2009 |
10 pages |
| Authors:
Charles J Ammon; Monica Maceira; PENNSYLVANIA STATE UNIV UNIVERSITY PARK
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| The objective of this work is to help improve seismic monitoring technology through the development and application of advanced multivariate inversion techniques to generate realistic, comprehensive, and high-resolution 3D models of the seismic structure of the crust and upper mantle that satisfy independent geophysical datasets. Our focus is on the region surrounding Iran from the east coast of the Mediterranean in the west, to Pakistan in the east, an area ... |
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| Estimating the Uncertainty and Predictive Capabilities of Three-Dimensional Earth Models |
30-Sep-2009 |
11 pages |
| Authors:
Stephen C Myers; Delaine T Reiter; William L Rodi; WESTON GEOPHYSICAL LEXINGTON MA
|
| Many three-dimensional models of seismic velocity structure in Eurasia have been developed in recent years by the seismic nuclear monitoring community. Most of these models are not accompanied by quantitative estimates of uncertainty, either in the model velocities themselves or in geophysical observables predicted by the models (e.g., body-wave travel times). Moreover, the various 3D models produced by these studies have not been compared to one another for their predictive ... |
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| Developments of Finite-Frequency Seismic Theory and Applications to Regional Tomographic Imaging |
31-Jan-2009 |
54 pages |
| Authors:
Xiaoping Yang; Yang Shen; SCIENCE APPLICATIONS INTERNATIONAL CORP (SAIC) ARLINGTON VA
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| We use banana-doughnut sensitivity kernels of teleseismic body waves to image the crust and mantle beneath eastern Eurasia. We have collected and processed available broadband data from both permanent stations and temporary networks in eastern Eurasia. In southeast Tibet, where a PASSCAL experiment provided a dense station coverage, a detailed study is carried out to obtain high-resolution P- and Svelocity models. A regional P-wave velocity model for eastern Eurasia is ... |
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| An Experimental Study of S Wave Generation by Fracture Damage in Underground Nuclear Explosions |
30-Sep-2008 |
7 pages |
| Authors:
Charles G Sammis; Ronald L Biegel; Ares J Rosakis; UNIVERSITY OF SOUTHERN CALIFORNIA LOS ANGELES
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| High-speed digital photography was used to observe the generation of S waves by explosions in fracture-damaged photoelastic Homalite plates. We found that either a preferred orientation of the pre-existing fractures or an anisotropic initial stress field produced significant S wave radiation in the far field. These experimental observations support theoretical predictions by Johnson and Sammis (2001). |
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| A New Regional 3-D Velocity Model for Asia from the Joint Inversion of P-Wave Travel Times and Surface-Wave Dispersion Data |
30-Sep-2008 |
10 pages |
| Authors:
Delaine T Reiter; William L Rodi; WESTON GEOPHYSICAL LEXINGTON MA
|
| Accurate travel-time predictions for regional seismic phases are essential for locating small seismic events with the accuracy needed for nuclear monitoring decisions. Travel times calculated through a three-dimensional (3-D) Earth model have the best chance of achieving acceptable prediction errors, if the model is constrained by sufficient data. With this motivation, we have developed a self-consistent 3-D P and S velocity model of the crust and upper mantle in a ... |
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| Turbulent Flow and Large Surface Wave Events in the Marine Boundary Layers |
Sep-2008 |
9 pages |
| Authors:
James C McWilliams; Peter P Sullivan; NATIONAL CENTER FOR ATMOSPHERIC RESEARCH BOULDER CO
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| The long term objective of our research for the High Resolution Air-Sea Interaction (HRES) Departmental Research Initiative (DRI) is to identify the couplings between large wave events, winds, and currents in the surface layer of the marine boundary layers. Turbulence resolving large eddy simulations (LESs) and direct numerical simulations (DNSs) of the marine atmospheric boundary layer (MABL) in the presence of time and space varying wave fields will be the ... |
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| Impacts of Ocean Waves on the Atmospheric Surface Layer: Simulations and Observations |
06 JUN 2008 |
79 pages |
| Authors:
Peter P. Sullivan; James C. McWilliams; W. K. Melville; NATIONAL CENTER FOR ATMOSPHERIC RESEARCH BOULDER CO MESOSCALE AND MICROSCALE METEOROLOGY DIV
|
| This this award investigated surface boundary layers and air-sea interaction with theoretical and numerical research. Our long term scientific objective was to explore the nature of intermittence, coherent structures, and turbulent fluxes and their coupling in the surface layers of the marine atmospheric and oceanic planetary boundary layers (PBL). Efforts were focused on the effects of surface gravity waves on the near-surface dynamics, surface fluxes, and coupling between the atmospheric ... |
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| Observations of Turbulent Fluxes and Turbulence Dynamics in the Ocean Surface Boundary Layer |
01-Jun-2008 |
117 pages |
| Authors:
Gregory P Gerbi; MASSACHUSETTS INST OF TECH CAMBRIDGE JOINT PROGRAM IN APPLIED OCEAN SCIENCE AND ENGINEERING
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| This study presents observations of turbulence dynamics made during the low winds portion of the Coupled Boundary Layers and Air-Sea Transfer experiment (CBLAST-low) in the ocean surface boundary layer. Observations include turbulent fluxes, turbulent kinetic energy, and the length scales of flux-carrying and energy-containing eddies. The observations of turbulent fluxes allowed the closing of heat and momentum budgets across the air-sea interface. The flux-carrying eddies are similar in size to ... |
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| Regional P-Coda for Stable Estimates of Body Wave Magnitude: Application to Novaya Zemlya and Nevada Test Site Events |
15-Apr-2008 |
24 pages |
| Authors:
Kevin Mayeda; WESTON GEOPHYSICAL LEXINGTON MA
|
| Regional seismic explosion monitoring requires the discrimination of small clandestine nuclear explosions from background earthquakes. most successful teleseismic discriminant, the so-called Ms:mb, discriminant, compares the long-period surface waves magnitude (Ms) with the period P-based body wave magnitude (mb). There are many studies underway to try and extend surface wave magnitude (Ms) estimation to re distances and smaller magnitudes. Another problem that is encountered is how to estimate mb so that ... |
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| P and S Wave Velocity Structure of the Crust and Upper Mantle Under China and Surrounding Areas From Body and Surface Wave Tomography |
31-Mar-2008 |
110 pages |
| Authors:
MASSACHUSETTS INST OF TECH CAMBRIDGE DEPT OF EARTH ATMOSPHERIC AND PLANETARY SCIENCES
|
| We have used a combination of travel-time and surface wave tomography to obtain compressional and shear wave velocity distributions in the crust and upper mantle under China and surrounding areas. We first determined 3-D P- and S-wave velocity structures for the crust and uppermost mantle using local and regional arrival time data. Travel-time data from the Annual Bulletin of Chinese Earthquakes (ABCE) and the International Seismological Centre (ISC/EHB) were used. ... |
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| Design and Optimization of Broadband High Impedance Ground Planes (HIGP) for Surface Mount Antennas |
MAR 2008 |
136 pages |
| Authors:
Murat Dogrul; AIR FORCE INST OF TECH WRIGHT-PATTERSON AFB OH SCHOOL OF ENGINEERING AND MANAGEMENT/DEPT OF ENGINEERING PHYSICS
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| Gain and bandwidth metrics of broad-band low-profile antennas severely deteriorate when they are placed conformally onto the conductive skins of air, sea, and ground platforms. This detrimental effect is primarily due to out-of-phase reflections from the conductive body interfering with the antenna's self radiation. Furthermore, lateral waves launched by the antenna couple into the thin substrate placed between the antenna and the platform, giving rise to surface waves resulting in ... |
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| Shipboard Survey Near the Philippines with a Coherent X-Band Radar |
26 FEB 2008 |
7 pages |
| Authors:
William J. Plant; WASHINGTON UNIV SEATTLE APPLIED PHYSICS LAB
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| The goal of this research was to survey microwave signatures of oceanographic features near the Philippine Island. To do this a dual-polarized, X-band Doppler radar was mounted on a ship cruising near the Philippine Islands and was used to image the surface signatures of oceanographic features. At the same time other investigators collected surface and subsurface data to determine environmental conditions and the characteristics of these features. By analyzing these ... |
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| Surface Wave Dispersion Measurements and Tomography From Ambient Seismic Noise in China |
20-Dec-2007 |
22 pages |
| Authors:
Xiaodong Song; ILLINOIS UNIV AT URBANA DEPT OF GEOLOGY
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| We have recently performed ambient noise tomography of China using the new national China Seismic Network and surrounding global and regional stations. For most of the station pairs, we can retrieve very good Rayleigh waves from ambient noise correlations using 18- months of continuous data at all distance ranges (100 km to 5000 km) and for periods down to about 8 s. We obtain Rayleigh wave group velocity dispersion measurements ... |
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| Continued Investigation of Small-Scale Air-Sea Coupled Dynamics using CBLAST Data |
30 SEP 2007 |
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| Authors:
Dick K. Yue; MASSACHUSETTS INST OF TECH CAMBRIDGE
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 | This study uses direct numerical simulation, large-eddy simulation, and large-wave simulation for both air and ocean turbulent flows with surface waves to investigate the dynamics of coupled air-sea boundary layers at relatively small spatial scales. With extensive simulation in collaboration with measurement, we identify and assess the key transport processes within the atmosphere-ocean wave boundary layer (WBL). This project obtains a physical foundation for the parameterization of the momentum, mass ... |
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| Sensitivity and Trade-Off Analysis of Wave Making Resistance and Stability of Small Water Plane Area Trimarans |
SEP 2007 |
273 pages |
| Authors:
Brian R. Boudreau; NAVAL POSTGRADUATE SCHOOL MONTEREY CA
|
| Recent concept ship designs have called for a vessel with the capability to lift and transport multiple medium displacement combatant boats, approximately 40 to 100 tons, at high speeds over thousands of nautical miles. One such design placed two small water plane area (SWATH) side hulls significantly aft of the center hull transom to facilitate a heavy duty hoist system. This thesis determines the optimal longitudinal and lateral positioning of ... |
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| Observed Oceanic Response over the Upper Continental Slope and Outer Shelf during Hurricane Ivan |
SEP 2007 |
27 pages |
| Authors:
William J. Teague; Ewa Jarosz; David W. Wang; Douglas A. Mitchell; NAVAL RESEARCH LAB STENNIS SPACE CENTER MS OCEANOGRAPHY DIV
|
| Hurricane Ivan passed directly over an array of 14 acoustic Doppler current profilers deployed along the outer continental shelf and upper slope in the northeastern Gulf of Mexico. Currents in excess of 2OO cm s-l were generated during this hurricane. Shelf currents followed Ekman dynamics with overlapping surface and bottom layers during Ivan's approach and transitioned to a dominant surface boundary layer as the wind Stress peaked. Slope currents at ... |
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| Studies on Three-Dimensional Slamming on Slender Ships |
10 MAY 2007 |
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| Authors:
Dick K. Yue; Yuming Liu; MASSACHUSETTS INST OF TECH CAMBRIDGE
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| The focus is on the understanding of the impact phenomenon at relatively low Froude number (Fr = O(1)). In particular, our objectives are to quantify the range of validity of existing asymptotic theories (using the high Froude number assumption, Fr >> 1), and to understand the gravity effect upon the impact process. This study is of direct relevance to accurate prediction of hydrodynamic loads associated with ship slamming and breaking ... |
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| Infra-Gravity Wave Input Toolbox (IGWT): User's Guide |
MAY 2007 |
12 pages |
| Authors:
Zeki Demirbilek; Okey G. Nwogu; Alan K. Zundel; ENGINEER RESEARCH AND DEVELOPMENT CENTER VICKSBURG MS COASTAL AND HYDRAULICS LAB
|
| Most harbor structures and harbor layouts are designed for protection against wind-generated (short-period) waves with periods of order 3-20 sec. However, Infra-Gravity (IG) waves, also referred to in this note as low-frequency or long-period waves, with periods on order of 30-600 sec, are generated by groups of short-period waves through nonlinear wave-wave interactions. These long-period waves can cause oscillations and resonance problems in harbors. Such low-frequency waves are responsible for ... |
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| Nearshore Canyon Experiment |
MAR 2007 |
4 pages |
| Authors:
Robert T. Guza; SCRIPPS INSTITUTION OF OCEANOGRAPHY LA JOLLA CA
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| The objective of the Nearshore Canyon Experiment (NCEX) was to understand the effect of complex continental-shelf bathymetry on surface gravity waves and on the breaking-wave-driven circulation onshore of the irregular bathymetry. The NCEX observations were the first extensive quantitative field measurements of the effect of severe alongshore bathymetric inhomogeneities (here a submarine canyon) on incident waves, and on the surfzone circulation. |
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| Attenuation of Ocean Waves by Ripples on the Seafloor |
MAR 2007 |
3 pages |
| Authors:
Robert T. Guza; William O'Reilly; SCRIPPS INST OF OCEANOGRAPHY LA JOLLA CA INTEGRATIVE OCEANOGRAPHY DIV
|
| Dissipation of hurricane waves over a broad, shallow shelf were observed during the SAX04/Ripples Experiment on the Florida Panhandle Gulf Coast. Nearly complete bottom dissipation of hurricane swell waves occurred in Apalachee Bay, where the shelf is approximately 200km wide. On the narrower 85km shelf off Fort Walton Beach, peak swell energy levels decreased by approximately a factor of 3, but were still energetic enough during Hurricane Ivan to destroy ... |
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| Development of a Three Dimensional Perfectly Matched Layer for Transient Elasto-Dynamic Analyses |
DEC 2006 |
152 pages |
| Authors:
Anthony N. Johnson; NAVAL POSTGRADUATE SCHOOL MONTEREY CA
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| A time-dependent, three-dimensional finite element approach to the development of a perfectly matched layer for numerical calculations of surface wave radiation in a half space is presented. The development of this new element required the coupling of a system of linear, second-order, partial differential equations which describe elastic wave propagation into a single weak-form (Galerkin) wave equation, from which the characteristics of a composite finite element matching layer were derived. ... |
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| Operating the Portable Seismic Pavement Analyzer |
DEC 2006 |
25 pages |
| Authors:
Haley P. Bell; ENGINEER RESEARCH AND DEVELOPMENT CENTER VICKSBURG MS GEOTECHNICAL AND STRUCTURES LAB
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| The portable seismic pavement analyzer (PSPA) is a non-destructive testing device that measures the seismic modulus of concrete pavements. This report provides guidance on how to operate the PSPA including (a) general use and recommendations of the PSPA, (b) processing data measured from the PSPA, (c) step-by-step instructions for replacing the batteries in the PS PA, (d) step-by-step instructions for removing and replacing the rubber pads on the bottom of ... |
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| Spectral Models Based on Boussinesq Equations |
03 OCT 2006 |
13 pages |
| Authors:
Jay Veeramony; James M. Kaihatu; NAVAL RESEARCH LAB STENNIS SPACE CENTER MS OCEANOGRAPHY DIV
|
| For a stationary wave field, spectral models represent the surface wave motion sufficiently accurately. There are however two drawbacks in using nonlinear spectral models: a) The computational time involved when simulating the random wave field; the number of operations needed is O(N2) (N is the number of frequency components). b) Spectral models are usually one-equation reduction of the two-equation time domain model, which does not then have the same characteristics ... |
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| Seafloor Ripples Created by Waves from Hurricane Ivan on the West Florida Shelf |
SEP 2006 |
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| Authors:
Colleen M. Bowers; MASSACHUSETTS INST OF TECH CAMBRIDGE
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| Recent studies have shown that the presence of sand ripples on the seabed improves sonar detection of buried mines at sub-critical angles. Sidescan sonar data of ripples off on the west Florida shelf were collected as part of ONR's Ripples Departmental Research Initiative (DRI) September 26-29th and November 7-9th, 2004. Hurricane Ivan, the strongest storm of the 2004 hurricane season, passed over the experiment site a week before the first ... |
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| Ocean Surface Winds from Space - A Collaborative Education Effort |
Sep-2006 |
7 pages |
| Authors:
Zorana Jelenak; Von; Joan M Ahn; Joseph M Sienkiewicz; Michael J Brennan; NATIONAL OCEANIC ATMOSPHERIC ADMINISTRATION/NESDIS SILVER SPRING MD
|
| Ocean surface winds play a significant role in the global ocean-atmosphere system. Surface winds drive the worlds ocean currents, transport atmospheric heat and moisture, force nutrient rich upwelling areas, create surface waves and swell, and can reach destructive force in both extratropical and tropical cyclones. Although the oceans cover 70% of the Earth's surface, the network of ocean wind observations obtained from conventional buoys and ships is very sparse. The ... |
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| Residual Stress, Micro- and Macrotexture in Surface-Enhanced Titanium Alloys: Their Nondestructive Inspection and Effects on High-Cycle Fatigue Properties |
MAY 2006 |
49 pages |
| Authors:
Chi-Sing Man; Tongguang Zhai; KENTUCKY UNIV LEXINGTON
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| An acousto-elastic method was developed to estimate the residual stress and texture of a flat metal surface by simultaneous measurement of Rayleigh waves and surface skimming longitudinal waves (or P waves). The method showed promise in the successful recovery of surface residual stress in an AA 7076-T651 aluminum sample surface-treated by low plasticity burnishing. The effects of sandblasting and shot peening on a commercially pure titanium, a Ti-6Al-4V titanium alloy, ... |
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| A Regional Seismic Experiment in India to Increase Knowledge of Velocity Structure |
MAY 2006 |
170 pages |
| Authors:
James F. Lewkowicz; Keith Priestley; Vinod Gaur; Jessie L. Bonner; Sara G. Russell; Delaine Ritter; Alessia Maggi; Supryio Mitra; WESTON GEOPHYSICAL LEXINGTON MA
|
| Weston Geophysical Corporation, Cambridge University and India Institute of Astrophysics formed a consortium in 2000 to deploy a network of high-quality broadband seismometers distributed across India. This network began operation in April 2001, and is now fully operational providing important data for studies focusing on the characterization of the velocity structure and propagation of seismic waves throughout Southern Asia. Each station consists of a Guralp CMG-3TD digital output seismometer plus ... |
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| Regional Small-Event Identification Using Networks and Arrays of Seismic and Acoustic Sensors |
APR 2006 |
59 pages |
| Authors:
Michael A. Hedlin; SCRIPPS INSTITUTION OF OCEANOGRAPHY LA JOLLA CA
|
| Our work under this contract has had three primary objectives, but with the common theme of using seismic data to distinguish mining blasts from all other event types. We have used spectral characteristics of whole waveforms to discriminate industrial blasts from instantaneous explosions and earthquakes. We applied the automated time-frequency discriminant (AFTD) to several datasets to test transportability and robustness of the algorithm. The main conclusions of this work, described ... |
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| Full Plant STWAVE: SMS Graphical Interface |
MAR 2006 |
11 pages |
| Authors:
Jane McKee Smith; Alan Zundel; ENGINEER RESEARCH AND DEVELOPMENT CENTER VICKSBURG MS COASTAL AND HYDRAULICS LAB
|
| The purpose of this Coastal and Hydraulics Engineering Technical Note (CHETN) is to describe the graphical interface for the full-plane version of the wave model STWAVE (Smith et al. 2001; Smith 2001; and Smith and Smith 2002) that has been added to the U.S. Army Corps of Engineers (USACE) Surface Water Modeling System (SMS). A subsequent publication will describe the capabilities added in the full plane version of the model. ... |
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| Duration- and Fetch-Limited Growth Functions of Wind-Generated Waves Parameterized With Three Different Scaling Wing Velocities |
11 FEB 2006 |
11 pages |
| Authors:
Paul A. Hwang; NAVAL RESEARCH LAB STENNIS SPACE CENTER MS OCEANOGRAPHY DIV
|
| Under steady wind forcing, wave development follows the duration- and fetch-limited growth laws. These growth functions are used extensively to obtain the sea state information when only limited observations of the environmental variables are available. Validation and verification of wave models also employ numerical experiments of duration- and fetch-limited wave growth as benchmark tests. The reference wind speed reported in most of the wave-growth data is the equivalent neutral wind ... |
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| High-Frequency Electromagnetic Propagation/Scattering Codes |
31 DEC 2005 |
160 pages |
| Authors:
MONOPOLE RESEARCH THOUSAND OAKS CA
|
| The objective of our effort was to develop computational methods for constructing high-frequency asymptotic solutions in scattering on perfectly conducting objects. The emphasis of the first stage of our work was to describe high frequency phenomena in terms of numerically implemented evolution of wavefronts associated with the propagating waves. The wavefront evolution algorithm is implemented for the leading high frequency mechanisms including: free-space propagation, reflection on smooth surfaces, wave-front splitting ... |
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| Internal Tidal Hydrodynamics and Ambient Characteristics of the Adriatic (ITHACA) |
DEC 2005 |
57 pages |
| Authors:
Mirko Orlic; Gordana B. Paklar; Vlado Dadic; Nenad Leder; Branka Grbec; Hrvoje Mihanovic; Miroslava Pasaric; Zoran Pasaric; ZAGREB UNIV (CROATIA)
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| Analysis of historical data has shown that in the middle Adriatic area strong cyclonic activity supports different weather types in winter, with frequent exchange of Sirocco and Bora events. During summer, this area is under the influence of subtropical high-pressure belt and consequently warm and dry weather conditions prevail. Sea temperatures at various depths of the Split-Gargano transect are characterized by isothermal conditions in late autumn and winter and rather ... |
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| High Frequency Electromagnetic Propagation/Scattering Codes |
DEC 2005 |
160 pages |
| Authors:
Thomas Jaroszewicz; Elizabeth Bleszynski; Marek Bleszynski; MONOPOLE RESEARCH THOUSAND OAKS CA
|
| The objective of our effort was to develop computational methods for constructing high-frequency asymptotic solutions in scattering on perfectly conducting objects. The emphasis of the first stage of our work was to describe high frequency phenomena in terms of numerically implemented evolution of wave-fronts associated with the propagating waves. The wave-front evolution algorithm is implemented for the leading high frequency mechanisms including: free-space propagation, reflection on smooth surfaces, wave-front splitting ... |
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| A Novel Approach for the Detection of Maneuvering Air Targets in Sea-Clutter Using High-Frequency Surface-Wave Radar |
DEC 2005 |
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| Authors:
T. Thayaparan; L. J. Stankovic; M. Dakovic; DEFENCE RESEARCH AND DEVELOPMENT CANADA OTTAWA (ONTARIO)
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| A novel time-frequency signal decomposition approach is evaluated for the detection of maneuvering air targets in sea-clutter using High-Frequency Surface-Wave Radar (HFSWR). This approach is based upon time-frequency analysis and its eigenvalue decomposition. Results demonstrate that the new approach provides an effective way for detecting and analyzing maneuvering air targets in heavily cluttered regions. In addition, the proposed approach successfully detects the maneuvering target in all cases of the experiment. ... |
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| Acoustic Focusing in Shallow Water and Bubble Radiation Effects |
20 OCT 2005 |
9 pages |
| Authors:
Grant B. Deane; SCRIPPS INSTITUTION OF OCEANOGRAPHY LA JOLLA CA MARINE PHYSICAL LAB
|
| The long-term goals of the "Acoustic Focusing in Shallow Water and Bubble Radiation Effects" project is as follows: (1) understand the role of wave-induced bubbles in the upper ocean boundary layer on the performance of underwater communications systems and ambient noise generation, (2) study the implications of focusing by surface gravity waves on Doppler sonar and acoustic communications systems in shallow and very shallow water, and (3) study the performance ... |
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| Bathymetric Mapping with QuickBird Data |
SEP 2005 |
62 pages |
| Authors:
Martin P. Densham; NAVAL POSTGRADUATE SCHOOL MONTEREY CA
|
| Two algorithms are used to determine bathymetry in the littoral region using QuickBird multi-spectral satellite observations. The algorithms determine water-leaving radiance and convert this to water depth values. The first algorithm uses a ratio of two wavebands and the second uses the sum of several wavebands. Relative bathymetric errors are determined for the clear water of Looe Key, United States, and the turbid water of Plymouth Sound, United Kingdom. Bathymetric ... |
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| Calibration of the M(sub s):m(sub b) Discriminant at the International Monitoring System Array NVAR (PS-47) |
SEP 2005 |
94 pages |
| Authors:
Jessie L. Bonner; Sara A. Russell; Ileana M. Tibuleac; David Russell; David G. Harkrider; Delaine T. Reiter; Robert H. Shumway; Robert Herrmann; Eugene Herrin; WESTON GEOPHYSICAL LEXINGTON MA
|
| Surface wave magnitude [M(sub s)] estimation for small events recorded at near-regional distances will often require a magnitude scale designed for Rayleigh waves with periods between 5 and 25 seconds. We have completed several studies aimed at examining the usefulness of existing and new formulas at estimating surface wave magnitudes at periods not restricted to approximately 20 seconds. In Chapter 1, we show that 7-second surface waves can be used ... |
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| Regional Variability and Predictability in the Upper Ocean |
23 MAY 2005 |
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| Authors:
Robert A. Weller; Joseph H. LaCasce; WOODS HOLE OCEANOGRAPHIC INSTITUTION MA DEPT OF PHYSICAL OCEANOGRAPHY
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| We pursued understanding of regional upper ocean and lower atmospheric variability in large part by participation in fleet exercises and examination of the realism of oceanographic and meteorological models. The exercises were MIREM (Mine Warfare Readiness Effectiveness Measuring) Programs focusing on the performance of Navy systems in the upper ocean and/or atmospheric boundary layer in the littoral environment. We conducted enhanced environmental monitoring, placing small, non-intrusive instruments on ships operating ... |
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| Non-Stationary Interference Cancellation in HF Surface Wave Radar |
14 APR 2005 |
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| Authors:
Giuseppe A. Fabrizio; Alex B. Gershman; Mike D. Turley; DEFENCE SCIENCE AND TECHNOLOGY ORGANISATION EDINBURGH (AUSTRALIA) INTELLIGENCE SURVEILLANCE AND RECONNAISSANCE DIV
|
| High frequency (HF) interference in surface wave over-the-horizon (OTH) radars typically exhibits a time-varying or non-stationary spatial structure. Adaptive beamformers that update the spatial filtering weight vector within the coherent processing interval (CPI) are likely to suppress such interference most effectively, but the intra-CPI antenna pattern fluctuations result in temporal de-correlation of the clutter which severely degrades sub-clutter visibility after Doppler processing. A robust adaptive beamformer that effectively suppresses non-stationary ... |
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| Progress in HFSWR Research at Harbin Institute of Technology |
14 APR 2005 |
8 pages |
| Authors:
Yongtan Liu; Rongqing Xu; Ning Zhang; HARBIN INST OF TECH (CHINA)
|
| The Experimental HF Surface Over-the-Horizon Radar set up in the late 1980's has been updated by the following attributes: (1) installation of multi-channel receivers with digitization at the second IF stage, (2) newly designed transmitting and receiving antennas, (3) wideband solid-state power amplifiers, (4) frequency synthesizer with low phase noise and flexible signal generator, (5) a new radar controller added to allow the automatic and manual control of the radar, ... |
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| Hybrid Antenna Amplifier: A Controllable High Power Microwave Source |
MAR 2005 |
47 pages |
| Authors:
Anatoli Shlapakovski; TOMSK POLYTECHNIC UNIV (RUSSIA) NUCLEAR PHYSICS INST
|
| This report results from a contract tasking Nuclear Physics Institute at Tomsk Polytechnic University as follows: The contractor will evaluate the concept of hybrid antenna-amplifiers, i.e., devices representing a combination of a surface wave antenna and a traveling wave tube. Theoretical investigations and numerical simulations (including particle-in-cell simulations and complex calculations using existing electromagnetic codes) as well as prototype experiments on electron beam transport (in the absence of the antenna ... |
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| Altimeter Measurements of Wind and Wave Modulation by the Kuroshio in the Yellow and East China Seas |
2005 |
8 pages |
| Authors:
Paul A. Hwang; NAVAL RESEARCH LAB STENNIS SPACE CENTER MS OCEANOGRAPHY DIV
|
| The Kuroshio is the major ocean current conveying heat and water mass in the Pacific Ocean. The impact of the Kuroshio on regional wind and wave distributions has been studied with spaceborne-altimeter measurements in the Yellow and East China Seas. In this region the Kuroshio trajectory is relatively stationary and the monsoon patterns dominate, making it an ideal natural laboratory for large scale air-sea-current interaction research. Major findings from this ... |
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| Modeling Antennas on Automobiles in the VHF and UHF Frequency Bands, Comparisons of Predictions and Measurements |
2005 |
5 pages |
| Authors:
Nicholas DeMinco; INSTITUTE FOR TELECOMMUNICATION SCIENCES BOULDER CO
|
| This paper describes comparisons of analysis and measurements of antenna patterns on automobiles in the VHF and UHF frequency bands. The actual measurements and analysis were performed at six different frequencies ranging from 41 MHz to 918 MHz. An antenna on a vehicle in a roadway environment in the presence of Earth does not have antenna patterns or input impedances as if it were located in free space or over ... |
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| Modeling of Sediment Mechanics for Mine Burial Prediction |
DEC 2004 |
11 pages |
| Authors:
Horst G. Brandes; H. R. Riggs; HAWAII UNIV HONOLULU
|
| Numerical model development and testing were carried out for the purpose of assessing the influence of seafloor liquefaction on the burial of mines in shallow water due to cyclic loading by surface water waves. This project was conducted as part of the Office of Naval Research Mine Burial Prediction program (Code 321). |
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| Waveform Modeling of the Crust and Upper Mantle Using S, Sp, SsPmP, and Shear-Coupled PL Waves for Improved Event Location, Focal Depth Determination, and Uncertainty Estimation |
06 OCT 2004 |
12 pages |
| Authors:
Jay Pulliam; Mrinal K. Sen; TEXAS UNIV AT AUSTIN
|
| During this contract's performance period, we intend to complete the development of a method for determining crust and upper mantle structure in seismic regions and evaluate its capacity to produce sufficiently accurate models for locating hypocenter of small-to moderate seismic events. Specifically, we will: 1) complete development of a waveform modeling approach to determine the structure of the crust and upper mantle in a broad region surrounding a broadband seismographic ... |
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| Concluding Analysis of IR Measurements of Microbreaking and Whitecaps |
30 SEP 2004 |
14 pages |
| Authors:
Andrew T. Jessup; Ruth Branch; WASHINGTON UNIV SEATTLE APPLIED PHYSICS LAB
|
| Analysis of existing field and laboratory measurements using infrared techniques to study wave breaking was concluded by accomplishing two tasks. The field data were from the Fluxes, Air-sea Interaction, and Remote Sensing (FAIRS) experiment that took place off Monterey, California, in the fall of 2000. The laboratory data were obtained at the NASA Goddard Wallops Flight Facility in 1998 and 2004. The first task was the use of infrared (IR) ... |
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| Synthesizing High-Frequency (1-25 HZ) Regional Phases at Large Distances (>1000 KM) Using Generalized Screen Propagators (GSP) |
SEP 2004 |
53 pages |
| Authors:
Ru-Shan Wu; Xiao-Bi Xie; Xianyun Wu; CALIFORNIA UNIV SANTA CRUZ CA INSTITUTE OF GEOPHYSICS AND PLANETARY PHYSICS
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| Based on the half-space screen propagator developed in our previous project, we successfully extended the method to the case of irregular surface topography by the conformal and non-conformal topographic transforms. Its validity and potential applications have been numerically demonstrated by comparing with the boundary element method. The new method can handle combined effects of small-scale heterogeneities (random media) and rough random topography on Lg wave propagation. It is also 2-3 ... |
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| Observations of Steep Wave Statistics in Open Ocean Waters |
AUG 2004 |
9 pages |
| Authors:
Nicholas V. Scott; Tetsu Hara; Paul A. Hwang; Edward J. Walsh; NAVAL RESEARCH LAB STENNIS SPACE CENTER MS OCEANOGRAPHY DIV
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| Breaking waves are a ubiquitous phenomenon of the world's oceans. They disrupt the aqueous boundary layer causing surface renewal, thereby enhancing the diffusion of gases and heat across the air-sea interface. Breaking waves are also responsible for the dissipation of wave energy and thus directly affect the evolution of the wind-wave spectrum. With advances in technology, new direct observations of the two-dimensional spatial surface wave topography have been made. These ... |
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| Multidimensional Solitons in Complex Media with Variable Dispersion: Structure and Evolution |
07 APR 2004 |
1 pages |
| Authors:
V. Yu. Belashov; A. V. Anoshen; KAZAN STATE UNIV (RUSSIA)
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| The problem of dynamics the multidimensional solitons in complex media with the dispersion is studied numerically The applications to physics of the FMS waves in a magnetized plasma, and the 2-dimensional surface waves on shallow water are discussed. |
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Reports by Keyword(s)
SURFACE WAVES
