| GigE Advanced Imaging Sensor |
23-Nov-2009 |
9 pages |
| Authors:
Lon van Sunshine; Peter Ham; BAE SYSTEMS NASHUA NH
|
 | An advanced sensor was developed and tested under this effort. This sensor uses an EMCCD with an active focal plane of 658 by 496 pixels, in conjunction with a controllable iris and wide field of view lens to provide situation awareness over full daylight to extreme dark conditions. The interface to the sensor is over GigE, allowing high data rate signal transmission. Intensive mechanical design was applied to advance the ... |
|
| Characterization of the Nonlinear Viscoelastic and Adhesive Properties of Polyurea and Characterization of Polyurea-Clad Metallic Structures |
14-Oct-2009 |
121 pages |
| Authors:
K Ravi-Chandar; K M Liechti; TEXAS UNIV AT AUSTIN CENTER FOR MECHANICS OF SOLIDS STRUCTURES AND MATERIALS
|
| This report describes an experimental effort to characterize the viscoelastic properties of polyurea and the failure of ductile materials at high strain rates. The viscoelastic properties of cast polyurea were determined under monotonic loading conditions, both in the confined compression and Arcan shear configurations. The nonlinear viscoelastic properties have been determined and validated by predicting the large deformation compression behavior. Expanding ring experiments were performed on Al 6061-O, Al 1100-H14 ... |
|
| Unified Regional Tomography and Source Moment Tensor Inversions Based on Finite-Difference Strain Green Tensor Databases |
30-Sep-2009 |
11 pages |
| Authors:
Wei Zhang; Xiaoping Yang; Yang Shen; Li Zhao; Zhigang Zhang; SCIENCE APPLICATIONS INTERNATIONAL CORP SAN DIEGO CA
|
| Seismic monitoring requires accurate source characterization in real time. Accurate 3D earth models are essential for accurate predictions of seismic observables and source characterization. While recovering the true earth structure has always been the goal of tomographic inversions, methods based on full wavefields in 3D reference models have several distinct advantages. Made possible by advances in high-performance computation, this full-wave approach accounts for complex wave propagation in 3D heterogeneous earth, ... |
|
| Mechanistic Investigations of Branched Macromolecules and Metal Nanocomposites for Nonlinear Optical Applications |
26-Sep-2009 |
29 pages |
| Authors:
Goodson; Theodore III; MICHIGAN UNIV ANN ARBOR
|
| Support from the Army Research Office (ARO) has provided the opportunity for studies encompassing a combined effort consisting of different experimental and synthetic methods to produce novel nonlinear optical (NLO) materials with enhanced properties. This included the development of new synthetic branched organic macromolecules with different central core groups such as benzene, nitrogen, phosphorous, carbon as well as adamantine. These investigations gave the opportunity to probe the importance of the ... |
|
| Modeling of Lamb Waves and Application to Crack Identification |
Sep-2009 |
115 pages |
| Authors:
Epameinondas Palmos; NAVAL POSTGRADUATE SCHOOL MONTEREY CA
|
| The objective of this study is to model Lamb waves generation and sensing for application to crack identification in engineering structures. Three topics were analyzed numerically using multiphysics finite element analysis. Initially, different types of Lamb wave generation techniques were investigated. A comparison between modeling the sinusoidal application of horizontal force (or displacement) as input and modeling the piezoelectric response of an actuator subjected to sinusoidal voltage input was performed. ... |
|
| Concepts for Functional Restoration of Barrier Islands |
Sep-2009 |
15 pages |
| Authors:
Julie D Rosati; ENGINEER RESEARCH AND DEVELOPMENT CENTER VICKSBURG MS ENVIRONMENTAL LAB
|
| This Coastal and Hydraulics Engineering Technical Note (CHETN) presents guidance for functional restoration of barrier islands. The concept of functional restoration is introduced here as an engineering and ecological design such that a barrier island can perform as a wave attenuator, storm surge buffer, and ocean boundary for an estuary, bay, and mainland over the defined project lifetime. Ecological design is required as part of the restoration to minimize initial ... |
|
| Free-Space Quantum Key Distribution using Multilevel Encoding via Transverse Field Modulation: Preprint |
01-Aug-2009 |
6 pages |
| Authors:
Mark T Gruneisen; AIR FORCE RESEARCH LAB KIRTLAND AFB NM
|
| Transverse modulation of the complex optical field defines sets of orthogonal states for multilevel quantum key distribution. Principles of holography are evaluated as a means of generating and sorting the single photon states. |
|
| Moored Observations to Define the Structure and Energetics of Non-Linear Internal Wave Generation over the New Jersey Shelf |
Aug-2009 |
10 pages |
| Authors:
Jonathan D Nash; OREGON STATE UNIV CORVALLIS COLL OF OCEANIC AND ATMOSPHERIC SCIENCES
|
| Non-Linear Internal Wave (NLIW) packets are ubiquitous, yet they arrive with a high degree of irregularity in coastal oceans. Through this award, three water-column moorings and four bottom landers were deployed during the New Jersey Shelf Shallow Water 2006 (SW06) experiment. These moorings span the generation region for NLIWs and have been used to (1) quantify the structure, energetics, and timing of O(100) wave packets, (2) elucidate wave formation, the ... |
|
| The Aggregate Behavior of Branch Points I - The Creation and Evolution of Branch Points (Postprint) |
19-Jun-2009 |
18 pages |
| Authors:
Darryl J Sanchez; Denis W Oesch; AIR FORCE RESEARCH LAB KIRTLAND AFB NM DIRECTED ENERGY DIRECTORATE
|
| It has long been known that branch points cause degradation in adaptive optic performance. Here, we begin a study on the aggregate nature of branch points, specifically beginning the process to relate branch points measured in the pupil to the upstream turbulence that created them. As such, we study not only the wave as measured in the telescope's pupil, but also the wave in the intervening region between the turbulence ... |
|
| A Preliminary Comparison of Daylit and Night C(2/n) Profiles Measured by Thermosonde |
20-Apr-2009 |
9 pages |
| Authors:
John R Roadcap; Paul Tracy; AIR FORCE RESEARCH LAB HANSCOM AFB MA SPACE VEHICLES DIRECTORATE
|
| The refractive index structure constant C(2/n) is needed to characterize optical wave propagation in a refractive turbulent scattering medium. A limited number of in situ measurements of C(2/n) made during day and night conditions from the surface to 10 km above sea level are compared in three different atmospheric boundary layer environments: dry convective, moist convective, and marine inversion. C(2/n) on average appears to be higher through the convective boundary ... |
|
| Identification of Helicon Plasma via Radial Magnetic Field Profiles (Preprint) |
07-Apr-2009 |
20 pages |
| Authors:
William Lewis; Michael P Reilly; George H Miley; AIR FORCE RESEARCH LAB EDWARDS AFB CA PROPULSION DIRECTORATE
|
| The propagation of Helicon waves in 5 cm cylindrical plasma has been identified by radial Bz magnetic field profiles. These profiles are correlated with radial plasma density profiles which show a transition from a broad uniform density distribution during inductive plasma to centrally peaked profile during helicon wave propagation. Additionally, the matching network circuit parameters have been analyzed to show a sharp drop in reflected power when the discharge supports ... |
|
| Analysis Solutions for Open-Channel Temperature Response to Unsteady Thermal Discharge and Boundary Heating |
Apr-2009 |
7 pages |
| Authors:
H S Tang; T R Keen; NAVAL RESEARCH LAB STENNIS SPACE CENTER MS OCEANOGRAPHY DIV
|
| Analytical solutions are derived for a one-dimensional model of the bulk temperature response of open-channel flow with unsteady and nonuniform heating at the upstream end, the water surface, and the riverbed. The solutions are explicit formulas comprised of transient terms, which play dominant roles in the upstream region, and equilibrium terms, which determine the temperature far downstream. The applicability of the solutions to practical problems is illustrated for two cases: ... |
|
| Ocean and Coastal Modeling: Nonlinear Acoustic Propagation |
27-Mar-2009 |
87 pages |
| Authors:
Juliette W Ioup; George E Ioup; Germana Peggion; Martin J Guillot; J A McCorquodale; Ioannis Y Georgiou; NEW ORLEANS UNIV LA
|
| This grant consisted of work divided into two parts. The first part, Ocean Modeling, was performed off-campus. The lead researcher was Dr. Germana Peggion of the Department of Physics at UNO. Her colleagues for this research were employees of the Oceanography Division of the Naval Research Laboratory at Stennis Space Center (NRL-SSC). The main objective of the ocean modeling portion of this grant was to collaborate with and assist NRL-SSC ... |
|
| In Vivo Determination of the Complex Elastic Moduli of Cetacean Head Tissue |
Mar-2009 |
38 pages |
| Authors:
Peter H Rogers; James S Martin; Michael D Gray; GEORGIA INST OF TECH ATLANTA SCHOOL OF MECHANICAL ENGINEERING
|
| A confocal ultrasonic elastography system was designed, developed, and tested with discrete scatterers and tissue phantoms. The former experiments demonstrated the ability to use ultrasound for remote generation and detection of vibrations in the audio frequency range. The latter experiments demonstrated the ability to remotely detect shear wave motion amplitude and phase as a function of depth along the ultrasonic beam and determine the wave propagation speed. Results from these ... |
|
| Design of Robust Adaptive Array Processors for Non-Stationary Ocean Environments |
20-Feb-2009 |
19 pages |
| Authors:
Kathleen E Wage; GEORGE MASON UNIV FAIRFAX VA
|
| The overall goal of this project is to design adaptive array processing algorithms that have good transient performance, are robust to mismatch, work with low sample support, and incorporate waveguide physics in a meaningful and robust way. To develop improved array processing algorithms for non-stationary environments, this project is investigating adaptive beam forming algorithms that can operate on a single-snapshot or a very limited number of snapshots. Spectral estimation methods, ... |
|
| Recursive Dispersion Relations in One-Dimensional Periodic Elastic Media |
Feb-2009 |
30 pages |
| Authors:
Ani P Velo; George A Gazonas; Erwin Bruder; Nancy Rodriquez; ARMY RESEARCH LAB ABERDEEN PROVING GROUND MD WEAPONS AND MATERIALS RESEARCH DIRECTORATE
|
| A frequency bandgap is a range of wave frequencies that are prohibited from passing through a medium. The dispersion relation, which links the frequency to the wave number, enables us to illustrate the bandgaps. In [E. H. Lee, A survey of variational methods for elastic wave propagation analysis in composites with periodic structures, in Dynamics of Composite Materials, E. H. Lee, ed., ASME, New York, 1972, pp. 122-138] and [E. ... |
|
| Lamb Wave Dispersion Compensation in Piezoelectric Wafer Active Sensor Phased-Array Applications |
Jan-2009 |
|
| Authors:
Victor Giurgiutiu; Buli Xu; Lingyu Yu; SOUTH CAROLINA UNIV COLUMBIA DEPT OF MECHANICAL ENGINEERING
|
 | Lamb-wave testing for structural health monitoring is complicated by the dispersion nature of the wave modes. The dispersion effect will result in a propagated wave with longer time duration, deformed envelop shape as compared to its excitation counterpart, and hard to be interpreted. This paper first reviews the dispersion compensation and removal algorithms. Second, it compares these two methods by applying them to two widely used low-frequency Lamb wave modes: ... |
|
| Adaptive Filter Techniques for Optical Beam Jitter Control and Target Tracking |
Dec-2008 |
117 pages |
| Authors:
Michael J Beerer; NAVAL POSTGRADUATE SCHOOL MONTEREY CA
|
| The objective of this research is to develop advanced control methods to attenuate laser beam jitter using a fast-steering mirror. Adaptive filter controllers using Filtered-X Least Mean Square (FX-LMS) and Filtered-X Recursive Least Square (FX-RLS) algorithms are explored. The disturbances that cause beam jitter include mechanical vibrations on the optical platform (narrowband) and atmospheric turbulence (broadband). Both feedforward filters (with the use of auxiliary reference sensor(s)) and feedback filters (with ... |
|
| Efficient THZ Source Based on Cascaded Optical Down-Conversion in Orientation-Patterned GaAs Structures |
20-Nov-2008 |
34 pages |
| Authors:
Xiaojun Yu; Walter Hurlbut; Vladimir Kozlov; James Harris; Anjie Lin; Paulina Kuo; Joe Schaar; Martin Fejer; Konstantin Vodopyanov; Candace Lynch; David Bliss; Yun-Shik Lee; STANFORD UNIV CA EDWARD L GINZTON LAB OF PHYSICS
|
| The goal of this DARPA TIFT project was to demonstrate an efficient room temperature source for THz imaging systems based on optical down-conversion in an orientation-patterned GaAs microstructure, incorporated into an optical resonant cavity, and pumped by a compact solid state laser. The main achievements are: (1) quasi-phase-matched (QPM) GaAs microstructures with periodic reversal of crystalline orientation, including orientation-patterned GaAs (OPGaAs), diffusion-bonded GaAs (DB-GaAs) and optically-contacted GaAs (OC-GaAs) suitable for ... |
|
| Creation of a Dynamical Stratospheric Turbulence Forecasting and Nowcasting Tool for High Altitude Airships and Other Aircraft |
20-Oct-2008 |
9 pages |
| Authors:
David C Fritts; NORTHWEST RESEARCH ASSOCIATES INC REDMOND WA
|
| We have now completed a Phase II development of an atmospheric decision aid (ADA) forecasting methodology for military, civilian, and commercial aircraft for which significant wave and turbulence activity may pose an operational or functional risk. The specific goal for MDA purposes was to create a forecasting methodology for turbulence activity at the expected High Altitude Airship (HAA) flight altitude of 22 km that specifically addresses all of the dominant ... |
|
| Shear Wave Generation by Decoupled and Partially Coupled Explosions |
30-Sep-2008 |
11 pages |
| Authors:
Heming Xu; Jeffry L Stevens; G E Baker; SCIENCE APPLICATIONS INC SAN DIEGO CA
|
| The objective of this project is to investigate the sources of shear wave generation by decoupled and partially coupled explosions, and the differences in shear wave generation between tamped and decoupled explosions. A perfectly spherical explosion at the center of a perfectly spherical cavity large enough to fully decouple the explosion would generate no shear waves, so all shear waves from decoupled explosions are due to asymmetries in and near ... |
|
| 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
|
| 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). |
|
| Wave Propagation from Complex 3D Sources Using the Representation Theorem |
30-Sep-2008 |
11 pages |
| Authors:
Heming Xu; Jeffry L Stevens; SCIENCE APPLICATIONS INTERNATIONAL CORP SAN DIEGO CA
|
| In spite of extensive prior research on the generation of seismic waves by underground nuclear explosions, it is still not possible to provide a complete explanation for the observed wavefields, particularly at regional distances. Spherically symmetric explosion models embedded in layered elastic media effectively model the P phases generated by explosions and the major characteristics of some reflected and transmitted phases. Nonlinear axisymmetric finite difference calculations of explosions, including gravity ... |
|
| Surface Wave Dispersion Measurements and Tomography from Ambient Seismic Noise Correlation in China |
30-Sep-2008 |
12 pages |
| Authors:
Zhen Xu; Xiaodong Song; Michael H Ritzwoller; Xinlei Sun; Sihua Zheng; Yingjie Yang; ILLINOIS UNIV AT URBANA-CHAMAPIGN
|
| We perform ambient noise tomography of China using the data from the China National Seismic Network and global and PASSCAL stations. The results so far are summarized below. (1) Dispersion measurements and tomography. For most of the station pairs, we retrieve good Rayleigh waveforms from ambient noise correlations using 18 months of continuous data at all distance ranges across the entire region (over 5000 km) and for periods from 70 ... |
|
| Seismic Tomography of the Arabian-Eurasian Collision Zone and Surrounding Areas |
30-Sep-2008 |
|
| Authors:
Haijiang Zhang; M N Van der Toksoz; Robert D Hilst; Youshun Sun; Levent Gulen; Dogan Kalafat; Huseyin S Kuleli; Chang Li; MASSACHUSETTS INST OF TECH CAMBRIDGE
|
| The objectives of this study are to determine P- and S-wave velocity structures in the crust and upper mantle and to characterize seismic wave propagation in the Arabian-Eurasian collision zone and surrounding areas, including Iran, Arabia, Eastern Turkey, and the Caucasus. The Arabian-Eurasian plate boundary is a complex tectonic zone shaped by continent-continent collision processes. In recent years the number of seismic stations has increased greatly in the region because ... |
|
| A Level Set Based Geometrical Eulerian Approach to Computing High Frequency Radar Cross Sections and Multiphase Semiclassical Limits of the Schrodinger Equation |
30-Jun-2008 |
|
| Authors:
Stanley Osher; LEVEL SET SYSTEMS INC PACIFIC PALISADES CA
|
| Wave propagation in the high frequency regime can be simplified using the geometrical optics approximation. We obtained an eikonal approximation for the phase and transport equations for the amplitude. The general strategy used to find the phase is to solve for its level sets, called wave fronts. This same strategy works to compute semiclassical solutions of Schrodinger's equation, which is the main topic we studied here. Traditional obstacles faced in ... |
|
| High-Speed Transmission Shadowgraphic and Dynamic Photoelasticity Study of Stress Wave and Impact Damage Propagation in Transparent Materials and Laminates Using the Edge-On Impact (EOI) Method |
MAR 2008 |
16 pages |
| Authors:
Elmar Strassburger; Parimal Patel; James W. McCauley; Christopher Kovalchick; K. T. Ramesh; Douglas W. Templeton; ARMY RESEARCH LAB ABERDEEN PROVING GROUND MD
|
| In order to accelerate the development of validated design and predictive performance models, the Army Research Laboratory, the U.S. Army Tank Automotive Research Development and Engineering Center, and the Material Center of Excellence at Johns Hopkins University have entered into a collaboration with The Ernst-Mach Institute (EMI) of Efringen-Kirchen, Germany. The unique, fully instrumented Edge-on Impact facility at EMI, modified for dynamic photoelasticity, is being used to quantify stress wave ... |
|
| An Experimental Technique for Developing Intermediate Strain Rates in Ductile Metals |
MAR 2008 |
194 pages |
| Authors:
IV Gardenier Hugh E.; AIR FORCE INST OF TECH WRIGHT-PATTERSON AFB OH GRADUATE SCHOOL OF ENGINEERING AND MANAGEMENT
|
| Quantifying the strain-rate sensitive dynamic properties of structural materials is an important area of research in the solid mechanics field. Property evaluation is typically accomplished using dynamic tests which involve rapid loading or impact of specimens. In these tests, inertial forces and wave propagation make it difficult to accurately record the material response to a loading condition at an equivalent location. Furthermore, these tests typically generate high strain rates (in ... |
|
| FeyRay Evaluation: 2007 |
08 FEB 2008 |
56 pages |
| Authors:
James K. Fulford; NAVAL RESEARCH LAB STENNIS SPACE CENTER MS ACOUSTIC SIMULATION MEASUREMENTS AND TACTICS BRANCH
|
| The capabilities of the FeyRay acoustic prediction model (version 1.12 Foreman 2007) are analyzed through comparison with the Navy Standard Parabolic Equation Model (NSPE), and the GRAB (Gaussian Ray Bundle eigenray propagation model) in a limited number of environments. Measurements of the relationship between GRAB and NSPE are designed to quantify the meaning of our FeyRay measurements in terms of another commonly used OAML model for Gaussian Beam propagation. The ... |
|
| Incorporating Rubble Mound Jetties in Elliptic Harbor Wave Models |
FEB 2008 |
14 pages |
| Authors:
Vijay Panchang; Jianfeng Zhang; Zeki Demirbilek; ENGINEER RESEARCH AND DEVELOPMENT CENTER VICKSBURG MS COASTAL AND HYDRAULICS LAB
|
| Simulation models based on the elliptic mild- or steep-slope wave equation are frequently used to estimate wave properties needed for harbor engineering calculations. To enhance the practical applicability of such models, a method is developed to accommodate the effects of rubble mound structures that are frequently found along the sides of harbor entrance channels. The results of this method are found to match those of other mathematical models under appropriate ... |
|
| Nonhydrostatic Hindcasts of High Amplitude Internal Waves in the Mid-Atlantic Bight |
30 JAN 2008 |
6 pages |
| Authors:
Patrick C. Gallacher; Michael Schaferkotter; William E. Avera; NAVAL RESEARCH LAB STENNIS SPACE CENTER MS OCEANOGRAPHY DIV
|
| From late July to early September 2006 an intense field program, Shallow Water 2006 (SW06), was conducted in the Mid-Atlantic Bight (MAB) off of the New Jersey coast The goal of the program is to the determine the environmental processes that affect shallow water acoustic propagation and scattering and to understand the dynamics of the generation and evolution of those processes a phenomena that dominates much of the hydrodynamics in ... |
|
| High-Order Methods For Wave Propagation |
JAN 2008 |
72 pages |
| Authors:
Miguel R. Visbal; Scott E. Sherer; Michael D. White; AIR FORCE RESEARCH LAB WRIGHT-PATTERSON AFB OH AIR VEHICLES DIRECTORATE
|
| In order to meet the demanding accuracy requirements in the simulation of wave propagation phenomena, a numerical approach based on high-resolution spatial schemes is presented. The time-domain AFRL code, FDL3DI, solves either the time-dependent Maxwell's equations (for CEM) or the Euler equations (for acoustics) employing 6th-order accurate compact-differences and low-pass spatial filters of up to 10th-order accuracy. The solver has been made applicable to general curvilinear grids through the incorporation ... |
|
| In Vivo Determination of the Complex Elastic Moduli of Cetacean Head Tissue |
Jan-2008 |
9 pages |
| Authors:
Peter H Rogers; David H Trivett; GEORGIA INST OF TECH ATLANTA SCHOOL OF MECHANICAL ENGINEERING
|
| The overall goal of this project is to determine the feasibility of in vivo, non-invasive measurement of the complex elastic moduli of cetacean head tissue. If this objective is met, measurement systems could be developed capable of measuring the complex elastic moduli of the head tissue of live, stranded cetaceans. The technical objective is to remotely generate and detect mid-frequency (1 to 10kHz) elastic waves within the body of a ... |
|
| Assessment of Acoustic Adaptations for Noise Compensation in Marine Mammals |
Jan-2008 |
5 pages |
| Authors:
Susan E Parks; PENNSYLVANIA STATE UNIV UNIVERSITY PARK APPLIED RESEARCH LAB
|
| The proposed research will address the fundamental theoretical issue of noise compensation mechanisms in the vocal communication of marine mammals. Noise compensation mechanisms are important for improving signal transmission with an energy limited source. A better understanding of marine mammal noise compensation mechanisms can potentially provide effective means of improving signal transmission in a noisy marine environment and for assessing the impact of manmade sounds on the use of sound ... |
|
| Modeling of Hurricane Impacts |
21 DEC 2007 |
|
| Authors:
Dano Roelvink; Ad Reniers; Ap van Dongeren; Jaap van Thiel de Vries; Jamie Lescinski; Robert McCall; Dirk-Jan Walstra; UNESCO-IHE INST FOR WATER EDUCATION DELFT (NETHERLANDS)
|
| This fifth interim report describes ongoing development and validation of the XBeach model as part of the MORPHOS project and other activities over the period September-December 2007 (period extended due to delay in funding). |
|
| Boussinesq Modeling of Wave Propagation and Runup over Fringing Coral Reefs, Model Evaluation Report |
DEC 2007 |
113 pages |
| Authors:
Zeki Demirbilek; Okey G. Nwogu; ENGINEER RESEARCH AND DEVELOPMENT CENTER VICKSBURG MS COASTAL AND HYDRAULICS LAB
|
| This report describes evaluation of a two-dimensional Boussinesq-type wave model, BOUSS-2D, with data obtained from two laboratory experiments and two field studies at the islands of Guam and Hawaii, for waves propagating over fringing reefs. The model evaluation had two goals: (a) investigate differences between laboratory and field characteristics of wave transformation processes over reefs, and (b) assess overall predictive capabilities of the model for reef systems with steep slopes ... |
|
| A Follow-up Study on Wireless Power Transmission for Unmanned Air Vehicles |
DEC 2007 |
109 pages |
| Authors:
Leng H. Toh; NAVAL POSTGRADUATE SCHOOL MONTEREY CA
|
| This thesis was a continuation in part of a NPS project relating to microwave wireless power transmission for micro air vehicles (MAVs). The concept of using microwaves for transferring power in free space has existed since the beginning of the 20th century. The emphasis of this thesis is the experimental study of powering micro air vehicles via the use of using a microstrip rectenna (rectifying antenna) at 10 GHz. A ... |
|
| Random Radar |
16 NOV 2007 |
17 pages |
| Authors:
John Reed; SET ASSOCIATES CORP ARLINGTON VA
|
| This STTR explores the details of designing a SAR type system that maps building interiors at close ranges with an entirely covert system. The program has defined a top level SAR operations parameter set, identified technical challenges specific to the Random Radar mission, and has delineated a design that meets those challenges. Wave propagation through buildings and their interiors has been characterized thoroughly. Near field SAR image formation equations, differing ... |
|
| Modeling of Mud-Wave Interaction: Mud-Induced Wave Transport & Wave-Induced Mud Transport |
NOV 2007 |
63 pages |
| Authors:
Johan C. Winterwerp; DELFT HYDRAULICS (NETHERLANDS)
|
| This report describes the set-up and mathematical-physical formulations of a model simulating the interaction between soft mud deposits and waves. This model presumes a two-layer schematization, the lower layer consisting of liquefiable mud of high density and viscosity, and the upper layer of low viscous water. From an analytical solution of the 2L schematization the dispersion relation for the wave propagation and attenuation is derived, which can be re-written in ... |
|
| Mountain Wave Analysis Using Fourier Methods |
01 OCT 2007 |
73 pages |
| Authors:
John R. Roadcap; AIR FORCE RESEARCH LAB HANSCOM AFB MA
|
| Eigenanalysis of temperature and wind profiles can reveal distinct resonances at mesoscale wavelengths. Fourier transform methods are well suited to analyze resonant modes such as mountain waves due, in part, to (1) their fast computation speed for large wave number domains compared to numerical forecast models and (2) their requirements for only a coarse horizontal background state. Common traits of Fourier mountain wave models include use of the Boussinesq approximation ... |
|
| Electromagnetic Wave Propagation in Optical Guiding Structures: Numerical Modeling |
11-Sep-2007 |
9 pages |
| Authors:
Natalia M Litchinitser; MICHIGAN UNIV ANN ARBOR OFFICE OF RESEARCH ADMINISTRATION
|
| We have developed a website on Numerical Modeling of Optical Waveguides (http://optical-waveguides-modeling.net) that contains a Waveguide Tutorial, which summarizes basic concepts of light propagation in optical waveguides, dispersive, and nonlinear properties, and a broad collection of free and commercial software available for numerical simulations of waveguiding structures, supplied with a short summary of its capabilities and potential applications, a list of references to research papers that utilize a particular software ... |
|
| Measurement of Non-Linear Internal Waves and Their Interaction with Surface Waves Using Coherent Real Aperture Radars |
SEP 2007 |
9 pages |
| Authors:
William J. Plant; WASHINGTON UNIV SEATTLE APPLIED PHYSICS LAB
|
| The objectives of the grant were to use a coherent real aperture radar to 1) study the interaction of surface waves with internal wave, the process that is responsible for the synthetic aperture radar (SAR) imagery of internal waves; 2) Determine the extent to which Doppler velocity modulations observed by coherent radars, including along-track interferometric SARs, are faithful representations of surface currents generated by internal waves; and 3) track the ... |
|
| A Feasibility Study of RF Time-Domain Reflectometry as a Railgun Armature Tracking Technique |
08 AUG 2007 |
13 pages |
| Authors:
S. Levinson; F. Stefani; E. Snyder; TEXAS UNIV AT AUSTIN INST FOR ADVANCED TECHNOLOGY
|
| Since past investigations have shown that radio frequency (RF) signal transmission in the bore of a railgun can be practical, the feasibility of using time domain reflectometry and well-established transmission line theory is investigated as a means to determine armature position during launch. This report describes the transmission line model of the HEMCL and initial measurements suggesting that such an approach might be used to provide dynamic armature position profiles. ... |
|
| Modeling Nearshore Waves for Hurricane Katrina |
AUG 2007 |
15 pages |
| Authors:
Jane M. Smith; ENGINEER RESEARCH AND DEVELOPMENT CENTER VICKSBURG MS
|
| Modeling of nearshore waves under extreme events presents challenges, including the interaction of waves with storm surge, wave generation by complex wind files, and wave dissipation in wetlands. The purpose of this technical note is to demonstrate the application of the Steady-State Spectral Wave model STWAVE for modeling nearshore waves during Hurricane Katrina. STWAVE is under development in the System-Wide Water Resources Program (SWWRP). |
|
| High Strain Rate Properties of Tantalum Processed by Equal Channel Angular Pressing |
AUG 2007 |
18 pages |
| Authors:
Philip J. Flater; Joel W. House; James M. O'Brien; William F. Hosford; AIR FORCE RESEARCH LAB EGLIN AFB FL MUNITIONS DIRECTORATE
|
| Current ingot refinement and solidification techniques used in tantalum processing often result in inconsistent mechanical properties. Subsequent processing by equal channel angular pressing (ECAP) has been shown to reduce or eliminate internal structural variations as well as part-to-part variability [2]. This paper presents the effects of ECAP processing on the properties of tantalum. The materials of interest are 2.5-inch round bar tantalum supplied by H.C. Starck and Cabot Supermetals. Three ... |
|
| Development of a Fully Interconnected Optical Network Architecture (FIONA) |
07 MAY 2007 |
56 pages |
| Authors:
Mark E. Daniel; NAVAL ACADEMY ANNAPOLIS MD
|
| Networks have been rapidly evolving over the last several decades and continue to do so today. This evolution has been driven by a need for increased performance, as characterized by increased data rates and larger bandwidth. This project focused on the development of a reconfigurable network architecture that connects existing Local Area Networks (LANs) to create an extended LAN. The network uses optical fiber and supports data transparency. This Fully ... |
|
| Humidity's Influence on Visible Region Refractive Index Structure Parameter Cn2 |
01 MAY 2007 |
8 pages |
| Authors:
Mark P. Chang; Carlos O. Font; G. C. Gilbreath; Eun Oh; PUERTO RICO UNIV MAYAGUEZ DEPT OF PHYSICS
|
| In the near-infrared and visible bandpasses optical propagation theory conventionally assumes that humidity does not contribute to the effects of atmospheric turbulence on optical beams. While this assumption may be reasonable for dry locations, we demonstrate that there is an unequivocal effect owing to the presence of humidity upon the strength of turbulence parameter, Cn 2, from data collected in the Chesapeake Bay area over 100 m length horizontal propagation ... |
|
| Modeling of Sound Wave Propagation in the Random Deep Ocean (Briefing Charts) |
Apr-2007 |
|
| Authors:
Jin S Xu; John Colosi; Tim Duda; MASSACHUSETTS INST OF TECH CAMBRIDGE
|
| These briefing charts cover the following topics: Ocean Environmental Measurements; Sound Wave Fluctuation Measurements; Modeling of Acoustic Wave Propagating through Random Deep Ocean; Garret & Munk Internal Wave Spectrum; Rytov Theory; Monte Carlo Numerical Simulations; and Comparison: Observations, Theory and Monte Carlo Simulations. |
|
| Through-the-Wall Imaging from Electromagnetic Scattered Field Measurements |
01 MAR 2007 |
125 pages |
| Authors:
Jerry Kim; NAVAL POSTGRADUATE SCHOOL MONTEREY CA
|
| We investigate an inverse imaging problem for TWI (Through-the-wall Imaging) using frequencies between 500 GHz and 1 THz. Starting from first principles, this thesis uses Maxwells equations to develop a model for the transmission Greens function. This simplified model is then used in a Lippman-Schwinger integral equation to predict the scattered field associated with interrogating THz waves. We investigate the effects of wave propagation through isotropic media, and present methods ... |
|
| Simulation of Radiowave Propagation in a Dense Urban Environment |
MAR 2007 |
65 pages |
| Authors:
Chris V. Chung; NAVAL POSTGRADUATE SCHOOL MONTEREY CA DEPT OF ELECTRICAL AND COMPUTER ENGINEERING
|
| One objective of this thesis was to investigate the effect of details, such as the windows of high-rise buildings, on the radio wave propagation in the dense urban environment through modeling and simulations. If adding windows does not significantly change the signal distribution on average, it may not be necessary to build such a detailed model. Simulations are performed using several levels of detail and the results compared to estimate ... |
|
Reports by Keyword(s)
WAVE PROPAGATION
