| Characterization of MEMS a Directional Microphone with Solid and Perforated Wings |
01-Jun-2009 |
57 pages |
| Authors:
Norbahrin Muamad; NAVAL POSTGRADUATE SCHOOL MONTEREY CA
|
 | This goal of this research is to characterize two microelectromechanical system (MEMS) based directional sound sensors with solid and perforated wings. The design of the sensors was based on the structure of Ormia ochracea fly's hearing system that has highly directional hearing through mechanical coupling of the eardrums. The sensors are made of 10 micron thick single crystal silicon layer with dimensions 1 x 2 mm2. The sensors were fabricated ... |
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| The Mechanosensitive Ca2+ Channel as a Central Regular of Prostate Tumor Cell Migration and Invasiveness |
Jan-2009 |
126 pages |
| Authors:
Owen P Hamill; Rosario Maroto; TEXAS UNIV MEDICAL BRANCH AT GALVESTON
|
| Our patch clamp studies indicate MscCa is expressed by the invasive prostate tumor cell PC-3. Anti-MscCa agents, Gd3+, GsmTx-4, and an anti-TRPC1 antibody block PC-3 cell migration. MscCa activity can be recorded over the surface of the PC-3 cell but is expressed at higher density on the rear compared with the front of the cell. This channel density gradient combined with a higher density of thapsigargin-sensitive Ca2+ stores in the ... |
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| Grid-Free Electrostatic Plasma Simulations |
09-Jul-2008 |
|
| Authors:
Andrew Christlieb; MICHIGAN STATE UNIV EAST LANSING
|
 | This report summarizes work done between September 2007 and June 2008 related to the development of a set of grid-free simulation tools for problems in plasma dynamics. As noted in the abstract on page one, the research objectives are: (1) to develop a grid-free field solver, fluid model, and kinetic model, (2) to evaluate these tools in comparison with traditional mesh-based methods, and (3) to demonstrate the capability of the ... |
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| Characterization of the MEMS Directional Sound Sensor Fabricated Using the SOIMUMPS Process |
01-Jun-2008 |
113 pages |
| Authors:
Antonios Dritsas; NAVAL POSTGRADUATE SCHOOL MONTEREY CA
|
| A micro-electro-mechanical system (MEMS) based directional sound sensor performance is characterized. The operation of directional sound sensor is based on the hearing organ of Ormia ochracea fly, which uses coupled bars hinged at the center to achieve the directional sound sensing. The MEMS sensor design considered in this thesis is fabricated using a process by which the sensor has two resonant vibrational modes: rocking and bending. The sensor is simulated ... |
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| Optical Imaging of the Nearshore |
20 MAR 2008 |
6 pages |
| Authors:
Robert A. Holman; OREGON STATE UNIV CORVALLIS COLL OF OCEANIC AND ATMOSPHERIC SCIENCES
|
| This grant supported a variety of studies in the area of littoral processes typically as revealed by the optical remote sensing data of the Argus Program. One principle theme was me development of algorithms for estimating relevant geophysical variables such as longshore currents and wave directional spectra from ground-based optical cameras. The second theme was the study of observed nearshore physics. Much of the latter work focused on the morpho-dynamics ... |
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| South China Sea Wave Characteristics During Typhoon Muifa Passage in Winter 2004 |
01-Jan-2008 |
49 pages |
| Authors:
Kuo-Feng Cheng; Peter C Chu; NAVAL POSTGRADUATE SCHOOL MONTEREY CA NAVAL OCEAN ANALYSIS AND PREDICTION LAB
|
| Ocean wave characteristics in the western Atlantic Ocean (Hurricane Region) to tropical cyclones have been investigated extensively, but not the regional seas in the western Pacific such as the South China Sea (Typhoon Region). This is due to the lack of observational and modeling studies in western Pacific regional seas. To fill this gap, Wavewatch-III (WW3) is used to study the response of the South China Sea (SCS) to Typhoon ... |
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| Modeling the Transformational Communications System Urban Land Mobile Satellite Channel |
DEC 2007 |
225 pages |
| Authors:
Timothy A. Gillespie; NAVAL POSTGRADUATE SCHOOL MONTEREY CA
|
| The success of the Transformational Communications System depends on providing high quality communications to the mobile user in any environment. A hurdle to this success is the urban Land Mobile Satellite Channel which experiences frequent and extended deep signal fades due to shadowing by man-made structures. The problem is exacerbated for the Communications-on-the-Move channel due to use of a directional antenna. This dissertation evaluates available empirical test data, develops an ... |
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| Directed Energy Weapons |
DEC 2007 |
96 pages |
| Authors:
Larry Welch; Robert Hermann; OFFICE OF THE UNDER SECRETARY OF DEFENSE FOR ACQUISITION TECHNOLOGY AND LOGISTICS WASHINGTON DC
|
| Directed energy continues to offer promise as a transformational "game changer" as the Department of Defense (DOD) encounters new asymmetric and disruptive threats, while facing increasingly sophisticated traditional challenges. Yet years of investment have not resulted in any current operational high-energy laser capability. In addition, the single high-energy laser program of record, the Airborne Laser (ABL) for boost phase missile defense, continues to experience delays and potential budget reductions. There ... |
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| MEMS PolyMUMPS-Based Miniature Microphone for Directional Sound Sensing |
SEP 2007 |
106 pages |
| Authors:
Timothy J. Shivok; NAVAL POSTGRADUATE SCHOOL MONTEREY CA
|
| A miniature directional sound sensor was fabricated using micro-electro-mechanical system (MEMS) technology based on the operational principle of Ormia ochracea fly s hearing organ. The fly uses coupled bars hinged at the center to achieve the directional sound sensing by monitoring the difference in vibration amplitude between them. The MEMS sensor design employed in this thesis was fabricated using the PolyMUMPs process. The sound sensor has two primary vibrational modes ... |
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| Measurements and Analysis of Reverberation and Clutter Data |
APR 2007 |
|
| Authors:
Dale D. Ellis; DEFENCE RESEARCH AND DEVELOPMENT ATLANTIC DARTMOUTH (CANADA)
|
| This report describes the objectives and some of the results from a three-year joint collaboration between DRDC Atlantic and the Applied Research Laboratory of The Pennsylvania State University to analyze and model reverberation data. Reverberation data up to 4 kHz had been collected on towed arrays during the initial (1996 2002) NATO MILOC Rapid Environmental Assessment exercises and more recent JRPs (Joint Research Projects) between the US, Canada, and SACLANTCEN ... |
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| Distributed Fault-Tolerant Quality Of Service Routing in Hybrid Directional Wireless Networks |
MAR 2007 |
129 pages |
| Authors:
II Llewellyn Larry C.; AIR FORCE INST OF TECH WRIGHT-PATTERSON AFB OH SCHOOL OF ENGINEERING AND MANAGEMENT
|
| This thesis presents a distributed fault-tolerant routing protocol (EFDCB) for QoS supporting hybrid mobile ad hoc networks with the aim of mitigating QoS disruption time when network failures occur. The experimental design presented in this thesis describes 22 experiments aimed at illustrating EFDCB's ability to handle fault-tolerance. The interpreted results show that EFDCB excels over a global rerouting protocol at this challenge which is the goal of this work. |
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| Basic Hearing and Echolocation Mechanisms of Marine Mammals: Measured Auditory Evoked Potential and Behavioral Experiments FY 2007 |
Jan-2007 |
8 pages |
| Authors:
Paul E Nachtigall; HAWAII INST OF MARINE BIOLOGY KAILUA HI MARINE MAMMAL RESEARCH PROGRAM
|
| Marine Mammal sensory systems have evolved to effectively use acoustic energy in the oceans. My objectives are to develop a basic understanding of hearing and echolocation so that knowledge can then be applied to the solution of practical problems as they arise. The most basic hearing measurement is the audiogram which is a series of thresholds across frequencies. Of the 85 species of cetaceans we now have audiograms on 14 ... |
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| Directionally Solidified Multifunctional Ceramics |
DEC 2006 |
17 pages |
| Authors:
Ali Sayir; CASE WESTERN RESERVE UNIV CLEVELAND OH
|
| In order to achieve a significant increase in toughening and to retain the toughness at elevated temperatures a new multifunctional approach is proposed. The multifunctionality were achieved through directional solidification of polyphase materials comprising the load-bearing and functional phases. The functional phases include shape recovery and health monitoring. In parallel, new ideas about the load bearing phases were investigated to achieve tougher materials. |
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| Selected Problems of Sniper Acoustic Localization |
01 OCT 2006 |
9 pages |
| Authors:
A. Kawalec; J. Pietrasinski; E. Danicki; MILITARY UNIV OF TECHNOLOGY WARSAW (POLAND)
|
| Acoustic signals of small arm's fire, the muzzle blast and the shock wave generated by a supersonic bullet in air, are difficult to mask and can be exploited for localization of the hidden sniper. The paper presents the system of acoustic measurements based on a number of both directional and omnidirectional microphones detecting the shock wave only, yielding exact solution for the sniper direction in spite of certain measurement errors ... |
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| Influence of Surface Roughness on The Specular Reflectance of Low Gloss Coatings Using Bidirectional Reflectance Measurements |
OCT 2006 |
70 pages |
| Authors:
Lisa M. Farrier; AIR FORCE RESEARCH LAB WRIGHT-PATTERSON AFB OH MATERIALS AND MANUFACTURING DIRECTORATE
|
| The objective of this study was to determine the effects of surface roughness and incident angle on the reflectance of low gloss coatings at grazing incidence. A specular peak has been identified from the forward scatter at longer wavelengths, 3.39 μm and 10.6 μm, for various painted surfaces. Depending on the surface roughness and wavelength, this specular component occurs at different angles. However, this effect has not been observed in ... |
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| On Validation of Directional Wave Predictions: Review and Discussion |
13 SEP 2006 |
41 pages |
| Authors:
W. E. Rogers; David W. Wang; NAVAL RESEARCH LAB STENNIS SPACE CENTER MS OCEANOGRAPHY DIV
|
| This report consists of supplementary materials for an article, accepted for publication in the "Journal of Atmospheric and Oceanic Technology," dealing with directional wave model validation by the same authors. These materials provide important background information for this companion paper, but were not included due to journal page limitations. Part I of this report provides a review of literature related to directional validation of wave models. Part II of this ... |
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| Rip Channel Migration in the Nearshore |
SEP 2006 |
55 pages |
| Authors:
Courtney M. Minetree; NAVAL POSTGRADUATE SCHOOL MONTEREY CA
|
| Video imaging data generated from the Naval Postgraduate School Imaging System (NAPSIS) during November 2004 to June 2006 was analyzed to determine the location of rip channels and track their morphology. During the study period, the rip fields constantly changed in shape, size, and location. Rip channels were found to have a mean migration southward at a rate of 0.16 meters per day with a standard deviation of 7.6 meters ... |
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| Sea Surface Backscatter Distortions of Scanning Radar Altimeter Ocean Wave Measurements |
Sep-2006 |
5 pages |
| Authors:
Edward J Walsh; C W Wright; NATIONAL AERONAUTICS AND SPACE ADMINISTRATION WALLOPS ISLAND VA WALLOPS FLIGHT CENTER
|
| This paper examines the distortions in the measured wave topography caused by sea surface backscatter variation within the 25 to 50 m antenna footprint of the one degree antenna beam of the NASA Scanning Radar Altimeter at its typical 1.5 to 3 km operating altitude and possible corrections to the directional wave spectra computed from the wave topography. |
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| Contra-Directional Two-Beam Coupling for Variable Rear Reflectivities in LiNbO3:Fe (Preprint) |
AUG 2006 |
17 pages |
| Authors:
Dean R. Evans; Gary Cook; Mohammad Saleh; Gerald Landis; AIR FORCE RESEARCH LAB WRIGHT-PATTERSON AFB OH MATERIALS AND MANUFACTURING DIRECTORATE
|
| 1. Coating the rear c-surface, we are able to produce a controlled range of rear reflectivity on a photorefractive LiNb03 crystal. 2. The contra-directional two-beam coupling does not vary significantly with reduced rear reflection. This agrees with theoretical calculation. 3. The time response of two beam coupling increases with reduced reflectivity. 4. Future work will produce similar work on other types of photorefractive crystals. |
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| Extracting Wind Sea and Swell from Directional Wave Spectra Derived from a Bottom-Mounted ADCP |
JUL 2006 |
|
| Authors:
James H. Churchill; Albert J. Plueddemann; Stephen M. Faluotico; WOODS HOLE OCEANOGRAPHIC INSTITUTION MA
|
| Recent advances in processing velocity data from bottom-mounted Acoustic Doppler Current Profilers (ADCPs) offer the capability of partitioning directional wave spectra of surface wave height in order to separate locally generated wind waves from swell. In the study described here, we have partitioned directional wavee spectra, derived from bottom-mounted ADCP measurements at the Martha's Vineyard Coastal Observatory (MVCO) south of Martha's Vineyard, MA, into dominant swell and locally generated wind-wave ... |
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| Coherent Structures and Chaos Control in High-Power Microwave Devices |
29 JUN 2006 |
|
| Authors:
Arje Nachman; Chiping Chen; MASSACHUSETTS INST OF TECH CAMBRIDGE
|
| This report summarizes research results obtained under the auspices of Air Force of Scientific Research, Grant No. F49620-03- 1-0230 (Chen, 2003). In particular, we conducted vigorous theoretical and computational investigations of coherent structures and chaos in a wide range of intense electron beam plasmas relevant to the development of high-power microwave sources for directed energy applications. The following is a brief summary of our research accomplishments in selected areas, while ... |
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| Strategic Plan: Initiating an Orthopaedic Residency at Womack Army Medical Center |
07 JUN 2006 |
49 pages |
| Authors:
David Mangelsdorff; Jason W. Harrington; WOMACK ARMY MEDICAL CENTER FORT BRAGG NC
|
| This Graduate Management Project delineates strategic planning necessary to implement an orthopaedic residency at Womack Army Medical Center (WAMC). Ginter, Swaney, and Duncan's strategic planning process as outlined in "Strategic Management of Healthcare Organizations" (2002) provides an ideal framework to address functional team responsibilities and areas in need of further analysis. Currently, strategic direction toward implementing an orthopaedic residency at WAMC does not exist. This projects' utility centers on insight ... |
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| Ship-Induced Noise Predictions in the Atlantic and the Pacific: A Comparison of Two Noise Models |
30 MAY 2006 |
75 pages |
| Authors:
Richard Heitmeyer; Stephen C. Wales; Lisa A. Pflug; Thomas J. Hayward; Iman W. Schurman; NAVAL RESEARCH LAB WASHINGTON DC
|
| This report describes differences in the ship-induced, bearing-elevation, noise directionality obtained from different noise models and interprets those differences in terms of the propagation and the environmental components of those models. The two noise models, RANDI and APL, both compute the noise as the incoherent sum of the individual ship contributions; they differ in both their propagation models (ANM and FEPE) and in their environmental models. The directionalities are computed ... |
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| Exploiting Semi-Directional Transceivers for Localization in Communication Systems |
MAR 2006 |
68 pages |
| Authors:
Andrew S. Crockford; AIR FORCE INST OF TECH WRIGHT-PATTERSON AFB OH SCHOOL OF ENGINEERING AND MANAGEMENT
|
| Localization is the process of determining relative, as well as absolute, positions of communicating devices. Traditionally, the process is conducted using range or directional estimates. In contrast, this research uses weak information to form relatively tight bounds on possible locations of communicating devices. Under certain conditions, achieved location estimation results are strong. However, these results are highly sensitive to the operating conditions of the proposed networks. More significant results were ... |
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| Combining Quality of Service and Topology Control in Directional Hybrid Wireless Networks |
MAR 2006 |
117 pages |
| Authors:
Michael C. Erwin; AIR FORCE INST OF TECH WRIGHT-PATTERSON AFB OH
|
| Recent advancements in information and communications technology are changing the information environment in both quantitative and qualitative measures. The developments in directional wireless capabilities necessitate the ability to model these new capabilities, especially in dynamic environments typical of military combat operations. This thesis establishes a foundation for the definition and consideration of the unique network characteristics and requirements introduced by this novel instance of the Network Design Problem (NDP). Developed ... |
|
| Use of Synthetic Nerve Grafts to Restore Cavernous Nerve Function Following Prostate Cancer Surgery: In Vitro and In Vivo Studies |
MAR 2006 |
9 pages |
| Authors:
Badrinath R. Konety; CALIFORNIA UNIV SAN FRANCISCO
|
| The hypothesis of this proposal is that interposition of micropatterned biodegradable polymer based nerve grafts to replace resected or damaged cavernous nerves can facilitate return of erectile function by engendering directional nerve growth in an animal model. Micropatterned grafts have been produced using a biodogradable polymer (PDFA) The groove oharaotceristics obtained by micropatterning will be optimized to allow maximal directional neurite growth have been optimized The effect of laminin +/- ... |
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| Computer-Aided Design and Optimization of High-Performance Vacuum Electronic Devices |
21 FEB 2006 |
10 pages |
| Authors:
John F. DeFord; Ben Held; Liya Chernyakova; John Petillo; SIMULATION TECHNOLOGY AND APPLIED RESEARCH INC MEQUON WI
|
| Project activities during the previous three months include the acquisition and setup of a LINUX cluster for use in optimization studies and the design and initial implementation of the optimization library, including support for the differential evolution and multi-directional search algorithms. Initial testing of the algorithms on several analytic functions has validated the implementations. Work on the implementation of user-interface support for the optimization library in the Analyst product has ... |
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| "Head, Not Tails:" How Best to Engage Theater Ballistic Missiles |
FEB 2006 |
72 pages |
| Authors:
Ronald C. Wiegand; AIR WAR COLL MAXWELL AFB AL
|
| Defending against theater and intercontinental ballistic missiles, potentially carrying nuclear, biological or chemical weapons, requires 100% effectiveness anything less continues to afford our enemies weapons of mass effect. If the U.S. is to be successful in answering this threat, a re-evaluation of boost phase intercept (BPI) options is in order. This paper highlights the ballistic missile threat and joint defense systems; provides an assessment of those systems; re-evaluates BPI merits; ... |
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| Comparison of Polarimetric SAR Techniques for the Measurement of Directional Ocean Wave Spectra |
25 JUL 2005 |
5 pages |
| Authors:
D. L. Schuler; J. S. Lee; E. Pottier; G. De Grandi; NAVAL RESEARCH LAB WASHINGTON DC REMOTE SENSING DIV
|
| Several methods have been investigated which use fully polarimetric synthetic aperture radar (POLSAR) data to measure directional ocean wave slope spectra. Independent techniques have been developed to measure wave slopes in the orthogonal SAR (azimuth/range) directions. In this paper, wave spectra measured using two polarimetric methods are investigated. Spectra developed using a) intensity-based polarimetric SAR methods and b) a more recent orientation/alpha angle algorithm are compared. NASA/JPL/AIRSAR L-band data from ... |
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| Adaptive Target Detection FLIR Imagery Using the Eigenspace Separation Transform and Principal Component Analysis |
JUN 2005 |
26 pages |
| Authors:
S. S. Young; Heesung Kwon; Nasser M. Nasrabadi; ARMY RESEARCH LAB ADELPHI MD
|
| In this paper, an adaptive target detection algorithm for forward- looking infrared (FLIR) imagery is proposed which is based on measuring differences between structural information within a target and its surrounding background. At each pixel in the image a dual window is opened where the inner window (inner image vector) represents a possible target signature and the outer window (consisting of a number of outer image vectors) represents the surrounding ... |
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| Performance Comparison of Agile Optical Network Architectures with Static Vs. Dynamic Regenerator Assignment |
Jan-2005 |
11 pages |
| Authors:
David Griffith; Kotikalapudi Sriram; Oliver Borchert; Giuseppe DiLorenzo; Richard Su; Nada Golmie; NATIONAL INST OF STANDARDS AND TECHNOLOGY GAITHERSBURG MD
|
| Agile all optical cross-connect (OXC) switches currently use an architecture in which regenerators and transceivers have pre-assigned and fixed directionality. However, technology is evolving to enable new OXC architectures in which the directionality of regenerators and transceivers can be dynamically assigned on demand for each connection that requires regeneration. We have performed detailed analytical and simulation studies to compare the two architectures. The analytical study is applicable to a single ... |
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| Performance of Directional Collision Avoidance in Multihop Wireless Networks |
2005 |
26 pages |
| Authors:
J. J. Garcia-Luna-Aceves; Yu Wang; CALIFORNIA UNIV SANTA CRUZ DEPT OF COMPUTER ENGINEERING
|
| This chapter analyzes the performance of directional collision avoidance schemes, in which antenna systems are used to direct the transmission and reception of control and data packets in channel access protocols based on four-way handshakes to try to avoid collisions. The first analytical model to consider directional reception and the possible difference in gain between omni-directional and directional transmissions is presented. Analytical results show that, when the directional collision avoidance ... |
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| Inertial Head Tracking for 3D Audio (Project "Sound Advice") |
DEC 2004 |
68 pages |
| Authors:
Jacque M. Joffrion; Frank A. Delsing; Christopher E. Hamilton; Michael D. Presnar; Stuart M. Reed; AIR FORCE FLIGHT TEST CENTER EDWARDS AFB CA
|
| This report presents the results of a limited evaluation of a 3D audio system on board a USAF C-12C aircraft under two system configurations: 3D Audio system coupled to a reference navigation system, and 3D Audio system coupled to an inertial head tracker. Testing began on 14 Oct 2004 and was completed on 2 Nov 2004 after eight sorties. Inertial head tracker angular accuracy when coupled to the aircraft frame ... |
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| Vertical Directionality of Low-Frequency Wind Noise and Vertical Array Optimization for the Wind Noise Limit |
27 AUG 2004 |
21 pages |
| Authors:
Thomas J. Hayward; Richard M. Heitmeyer; NAVAL RESEARCH LAB WASHINGTON DC
|
| Normal mode-based noise modeling is applied to investigate the structure and the environment dependence of vertical wind noise directionality and the optimal design of vertical arrays for detection in a wind noise background, using, as examples, two deep-water sites, one in the North Atlantic and the other in the North Pacific. The contributions to the noise directionality of the overhead (direct-path), surface-interacting, and sediment- interacting components of the noise field ... |
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| User's Manual for Long-Range Swell Forecasting Model |
27 FEB 2004 |
22 pages |
| Authors:
Y. L. Hsu; James D. Dykes; William C. O'Reilly; NAVAL RESEARCH LAB STENNIS SPACE CENTER MS OCEANOGRAPHY DIV
|
| At many parts of the world's coasts, swell waves arriving from a distant generation region are an important part of the local wave climate. To provide accurate swell forecasting, a ray tracing swell model was developed using directional wave spectra from a global wave model as input. The model propagates swell energy from source regions to the forecast sites along great circle routes. The effect of island blocking is considered ... |
|
| Directionally Solidified Eutectic Ceramics; In-Situ Composites for High Temperature Structural Applications |
25 FEB 2004 |
111 pages |
| Authors:
Ali Sayir; CASE WESTERN RESERVE UNIV CLEVELAND OHDEPT OF MATERIALS SCIENCE AND ENGINEERING
|
| Eutectics are multiphase structures formed by the cooperative growth of two or more phases. Although the internal structure can vary widely, the development of continuous rods or plates in a matrix can be achieved and, within limits, can be controlled or "tailored" through directional solidification. The eutectic architecture of a continuous reinforcing phase within a higher volume phase or matrix, can be described as a naturally occurring in-situ composite. In-situ ... |
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| Directional Collision Avoidance in Ad Hoc Networks |
2004 |
15 pages |
| Authors:
Yu Wang; J. J. Garcia-Luna-Aceves; CALIFORNIA UNIV SANTA CRUZ DEPT OF COMPUTER ENGINEERING
|
| This paper analyzes the performance of directional collision avoidance schemes, in which antenna systems are used to direct the transmission and reception of control and data packets in channel access protocols based on four-way handshakes to try to avoid collisions. The first analytical model to consider directional reception and the possible difference in gain between omni-directional and directional transmissions is presented. Analytical results show that, when the directional collision avoidance ... |
|
| Fetch-Limited Wind Wave Generation on the Continental Shelf |
DEC 2003 |
93 pages |
| Authors:
Kristen P. Watts; NAVAL POSTGRADUATE SCHOOL MONTEREY CA
|
| The growth of wind waves in coastal areas is limited by the fetch. Understanding this sheltering effect of the coastline on the nearshore wave climate is of critical importance for Navy operations (e,g, amphibious assault and mine countermeasures) in shallow water. Whilst the effect of fetch limitation on the development of the wave field is well understood, the effects of bottom topography, the presence of swell and its interaction with ... |
|
| Optical True-Time Delay Module (OTTDM) for Wideband Multiple Beam Phased Array Operation |
13 NOV 2003 |
53 pages |
| Authors:
Ray T. Chen; TEXAS UNIV AT AUSTIN DEPT OF ELECTRICALAND COMPUTER ENGINEERING
|
| There are many communication and radar applications requiring antennas with high directionality and narrow beam width. Typically, the width and directivity of the radiation pattern of a single radiating antenna element is insufficient for these applications. One method of improving these limitations is to increase the element aperture. A typical approach is to place the radiating element at the focal point of a large parabolic dish. However, for many mobile ... |
|
| Solid State Research Quarterly Technical Report 2003:2 |
17 OCT 2003 |
|
| Authors:
MASSACHUSETTS INST OF TECH LEXINGTON LINCOLN LAB
|
| A test bed using UV light-emitting diodes for detecting biological agent aerosols has been designed. An experimental apparatus was used to measure the elastic scattering and fluorescence signals from single bacterial spores illuminated by low-power 408-nm laser diode radiation. GaSb/GaInAsSb/GaSb epilayers have been transferred to GaAs wafers by atomic wafer fusion without mechanical pressure at temperatures as low as 350 deg C, followed by GaSb substrate removal. The fusion without ... |
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| A Tri-Modal Directional Modem Transducer |
Sep-2003 |
8 pages |
| Authors:
A L Butler; J L Butler; W Dalton; J Baker; P Pietryka; J A Rice; IMAGE ACOUSTICS INC COHASSET MA
|
| With suitable voltage distribution, higher order extensional modes of a piezoelectric cylinder can be excited which produce directional radiation patterns. These modal radiation patterns can then be combined to synthesize desired beam patterns which may be steered by incrementing the excitation. This paper describes a directional modem communication transducer which uses the combined acoustic response of the first three extensional modes of vibration of a piezoelectric ceramic cylinder, a method ... |
|
| Directional Recrystallization Processing |
31 JUL 2003 |
17 pages |
| Authors:
I. Baker; H. J. Frost; THAYER SCHOOL OF ENGINEERING HANOVER NH
|
| Fundamental research has been undertaken to understand how key microstructural parameters (grain size, particle spacing) interact with the processing conditions (temperature, rate of hot zone movement, temperature gradient in front of the hot zone) to control the microstructural evolution during directional recrystallization processing. The work involved close coupling of experiments with computer simulations. The computer simulation, in part, was to guide the choice of experimental parameters. A front-tracking grain-growth model ... |
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| Way-Finding and Maritime Emergency Signs |
14 MAY 2003 |
|
| Authors:
Michael May; DANISH MARITIME INST LYNGBY (DENMARK)
|
| Some visual and semantic problems in emergency signs and maps on passenger ships will be discussed using examples from Danish ferries that were studied as part of a European project on design for Mustering and Evacuation of Passengers ("MEPdesign"). Starting point are earlier findings on the effectiveness of signs versus (You-Are-Here) maps for wayfinding in buildings. Focus is on problems with the interpretation of emergency signs in the context of ... |
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| Concept and Technology Exploration for Transparent Hearing |
MAY 2003 |
142 pages |
| Authors:
William L. Chapin; Patrick M. Zurek; Barbara Shinn-Cunningham; Nathaniel Durlach; Mark Bolas; AUSIM INC MOUNTAIN VIEW CA
|
| Modern militaries are challenged to physically protect open-field personnel from a great variety of life and effectiveness threats, including chemical, biological, laser, ballistic, and percussive weapons. Many chemical and biological threats require covering all orifices, including the ears, to achieve minimal protection. Additionally, warfighting involves operating in very close proximity to loud equipment, from which the noise can degrade an individual 5 auditory perception, and over time can degrade general ... |
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| Directional Properties of Surface Waves Observed With HF Radar |
17 MAR 2003 |
6 pages |
| Authors:
Lucy R. Wyatt; SHEFFIELD UNIV (UNITED KINGDOM) DEPT OF APPLIED MATHEMATICS
|
| The goal of the work at Sheffield is to demonstrate that wave measurements obtained using HF radars are of sufficient accuracy and availability for them to contribute to the investigation of changes to the directional spectrum of waves subject to meteorological bathymetric and current variability in coastal environments for both scientific and operational applications. This report summarizes the measurements made with the OSCR HF radar in collaboration with the University ... |
|
| Free Electron and Solid State Lasers Development for Naval Directed Energy |
DEC 2002 |
|
| Authors:
Aristeidis Kalfoutzos; NAVAL POSTGRADUATE SCHOOL MONTEREY CA
|
| A MW level FEL is being designed with a short a Rayleigh length resonator to increase the spot size at the mirrors and to avoid mirror damage. In this thesis, it is found that it is desirable to focus the electron beam to improve the FEL extraction efficiency. Three-dimensional simulations show that the focused electron beam increases the extraction efficiency far beyond the desired value of 0.7%. It is also ... |
|
| Coherent Structures and Chaos in Beam Plasmas |
27 FEB 2002 |
23 pages |
| Authors:
Chiping Chen; MASSACHUSETTS INST OF TECH CAMBRIDGE PLASMA FUSION CENTER
|
| This report summarizes our research carried out under the auspices of the above referenced grant from December 1. 1999 to November 30, 2002. The goal of this research was to investigate coherent structures and chaos in beam plasmas in regimes relevant to the development of advanced high-power microwave (HPM) sources for directed energy applications. The report is organized as follows. In Sections 1-5, a brief summary of our research accomplishments ... |
|
| A Biological Model for Directional Sensing of Seismic Vibration |
25 FEB 2002 |
9 pages |
| Authors:
R. N. Miles; R. B. Cocroft; STATE UNIV OF NEW YORK AT BINGHAMTON DEPT OF MECHANICAL ENGINEERING
|
| There are many applications for a compact device that is capable of indicating the direction of propagation of substrate vibration. In order to develop effective devices for this purpose, it can be helpful to examine biological systems that have evolved specialized sensory systems for finding a vibration source. We are studying an insect model of vibration localization that provides an approach to directional vibration sensing over very small spatial scales. ... |
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| Adaptive Beach Monitoring |
JAN 2002 |
10 pages |
| Authors:
William A. Kuperman; SCRIPPS INSTITUTION OF OCEANOGRAPHY LA JOLLA CA MARINE PHYSICAL LAB
|
| The long-term goal of the Marine Physical Laboratory's Adaptive Beach Monitoring (ABM) program is to determine the capabilities of small on-shore and off-shore seismoacoustic arrays along with directional wave and current sensors to provide the amphibious force commander with a covert monitoring capability of shore-based as well as near-shore enemy forces, near- shore current and wave dynamics, and beach surf conditions. |
|
| Directional Distributions and Mean Square Slopes of Surface Waves |
2002 |
9 pages |
| Authors:
Paul A. Hwang; David W. Wang; NAVAL RESEARCH LAB STENNIS SPACE CENTER MS OCEANOGRAPHY DIV
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| Field observations show that the crosswind component constitutes a significant portion of the ocean surface mean square slope. The average ratio between the crosswind and upwind mean square slope components is 0.88 in slick- covered ocean surfaces. This large crosswind slope component cannot be explained satisfactorily based on our present models of ocean wave directional distributions. Two-dimensional spectral analysis of 3D ocean surface topography reveals that bimodal directional distribution is ... |
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Reports by Keyword(s)
DIRECTIONAL
