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Articles 31 - 53 of 53
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Derivation And Application Of A Conserved Orbital Energy For The Inverted Pendulum Bipedal Walking Model, Jerry E. Pratt, Sergey V. Drakunov
Derivation And Application Of A Conserved Orbital Energy For The Inverted Pendulum Bipedal Walking Model, Jerry E. Pratt, Sergey V. Drakunov
Publications
We present an analysis of a point mass, point foot, planar inverted pendulum model for bipedal walking. Using this model, we derive expressions for a conserved quantity, the “Orbital Energy”, given a smooth Center of Mass trajectory. Given a closed form Center of Mass Trajectory, the equation for the Orbital Energy is a closed form expression except for an integral term, which we show to be the first moment of area under the Center of Mass path. Hence, given a Center of Mass trajectory, it is straightforward and computationally simple to compute phase portraits for the system. In fact, for …
Doppler Ducting Of Short-Period Gravity Waves By Midaltitude Tidal Wind Structure, Jonathan B. Snively, Victor P. Pasko, Michael J. Taylor, Wayne K. Hocking
Doppler Ducting Of Short-Period Gravity Waves By Midaltitude Tidal Wind Structure, Jonathan B. Snively, Victor P. Pasko, Michael J. Taylor, Wayne K. Hocking
Publications
Multiwavelength airglow image data depicting a short-period (∼4.9 min) atmospheric gravity wave characterized by a sharp leading front have been analyzed together with synoptic meteor radar wind data recorded simultaneously from Bear Lake Observatory, Utah (41.6°N, 111.6°W). The wind data suggest the presence of a semidiurnal tide with horizontal winds peaking at around 60 m/s along the SSE direction of motion (170° from north) of this short-period wave. It was found that the gravity wave was most probably ducted because of the Doppler shift imposed by this wind structure. A marked 180° phase shift was observed between the near-infrared OH …
New Techniques To Determine Ages Of Open Clusters Using White Dwarfs, E. J. Jeffery, Ted Von Hippel, Et Al.
New Techniques To Determine Ages Of Open Clusters Using White Dwarfs, E. J. Jeffery, Ted Von Hippel, Et Al.
Publications
Currently there are two main techniques for independently determining the ages of stellar populations: main-sequence evolution theory (via cluster isochrones) and white dwarf cooling theory. Open clusters provide the ideal environment for the calibration of these two clocks. Because current techniques to derive cluster ages from white dwarfs are observationally challenging, we discuss the feasibility of determining white dwarf ages from the brighter white dwarfs alone. This would eliminate the requirement of observing the coolest (i.e., faintest) white dwarfs. We discuss our method for testing this new idea, as well as the required photometric precision and prior constraints on metallicity, …
Bifurcations Of Plane Wave (Cw) Solutions In The Complex Cubic-Quintic Ginzburg-Landau Equation, S.C. Mancas, S. Roy Choudhury
Bifurcations Of Plane Wave (Cw) Solutions In The Complex Cubic-Quintic Ginzburg-Landau Equation, S.C. Mancas, S. Roy Choudhury
Publications
Singularity Theory is used to comprehensively investigate the bifurcations of the steady-states of the traveling wave ODEs of the cubic-quintic Ginzburg-Landau equa- tion (CGLE). These correspond to plane waves of the PDE. In addition to the most general situation, we also derive the degeneracy conditions on the eight coefficients of the CGLE under which the equation for the steady states assumes each of the possible quartic (the quartic fold and an unnamed form), cubic (the pitchfork and the winged cusp), and quadratic (four possible cases) normal forms for singularities of codimension up to three. Since the actual governing equations are …
The Complex Cubi-Quintic Ginzburg-Landau Equation: Hopf Bifurcations Yielding Traveling Waves, S.C. Mnacas, S. Roy Choudhury
The Complex Cubi-Quintic Ginzburg-Landau Equation: Hopf Bifurcations Yielding Traveling Waves, S.C. Mnacas, S. Roy Choudhury
Publications
In this paper we use a traveling wave reduction or a so{called spatial approxima- tion to comprehensively investigate the periodic solutions of the complex cubic{quintic Ginzburg{Landau equation. The primary tools used here are Hopf bifurcation theory and perturbation theory. Explicit results are obtained for the post{bifurcation periodic orbits and their stability. Generalized and degenerate Hopf bifurcations are also brie y considered to track the emergence of global structure such as homoclinic orbits.
Gps-Based Steering Needle Instrument, Carl Edward Wischmeyer
Gps-Based Steering Needle Instrument, Carl Edward Wischmeyer
Publications
A a flight instrument enabling a pilot to intercept and precisely follow a predefined GPS track. The instrument known as a GPS steering indicator-provides a visual display which is similar in appearance to other aircraft instruments (and therefore instantly recognizable to nearly all pilots). However, the instrument is preferably differentiated somewhat in its visual appearance to convey to the pilot the fact that it displays steering commands rather than cross track error. An indicator needle deflects to instruct the pilot which way to turn and how much to turn in order to intercept and fly along a predefined GPS track. …
The Resolved Stellar Populations Of A Dwarf Spheroidal Galaxy In The Virgo Cluster, Patrick R. Durell, Ted Von Hippel, Et Al.
The Resolved Stellar Populations Of A Dwarf Spheroidal Galaxy In The Virgo Cluster, Patrick R. Durell, Ted Von Hippel, Et Al.
Publications
We report on the discovery of a faint (MV ~ -10.6 ± 0.2) dwarf spheroidal galaxy on deep F606W and F814W Hubble Space Telescope images of a Virgo intracluster field. The galaxy is easily resolved in our images, as our color magnitude diagram (CMD) extends 1 magnitude beyond the tip of the red giant branch (RGB). Thus, it is the deepest CMD for a small dwarf galaxy inside a cluster environment. Using the colors of the RGB stars, we derive a metal abundance for the dwarf of [M/H] = -2.3 ± 0.3 and show that the metallicity dispersion …
The Metallicity Distribution Of Intracluster Stars In Virgo, Benjamin F. Willaims, Ted Von Hippel, Et Al.
The Metallicity Distribution Of Intracluster Stars In Virgo, Benjamin F. Willaims, Ted Von Hippel, Et Al.
Publications
We have used the Hubble Space Telescope's Advanced Camera for Surveys (ACS) to detect and measure ~5300 stars in a single intracluster field in the Virgo Cluster. By performing F606W and F814W photometry on these stars, we have determined their metallicity distribution function and constrained the types of stars present in this portion of Virgo's intracluster space. Based on the small number of stars detected that were brighter than the red giant branch (RGB) tip, we suggest that in this region, Virgo's intracluster stars are mostly old (10 Gyr). Through analysis of the RGB stars themselves, we determine that …
Time-Resolved Ducting Of Atmospheric Acoustic-Gravity Waves By Analysis Of The Vertical Energy Flux, Yonghui Yu, Michael P. Hickey Ph.D.
Time-Resolved Ducting Of Atmospheric Acoustic-Gravity Waves By Analysis Of The Vertical Energy Flux, Yonghui Yu, Michael P. Hickey Ph.D.
Publications
A new 2-D time-dependent model is used to simulate the propagation of an acoustic-gravity wave packet in the atmosphere. A Gaussian tropospheric heat source is assumed with a forcing period of 6.276 minutes. The atmospheric thermal structure creates three discrete wave ducts in the stratosphere, mesosphere, and lower thermosphere, respectively. The horizontally averaged vertical energy flux is derived over altitude and time in order to examine the time-resolved ducting. This ducting is characterized by alternating upward and downward energy fluxes within a particular duct, which clearly show the reflections occurring from the duct boundaries. These ducting simulations are the first …
Soldier/Hardware-In-The-Loop Simulation-Based Combat Vehicle Duty Cycle Measurement: Duty Cycle Experiment 2, Mark Brudnak, Mike Pozolo, Victor Paul, Syed Mohammad, Marc Compere, Et Al.
Soldier/Hardware-In-The-Loop Simulation-Based Combat Vehicle Duty Cycle Measurement: Duty Cycle Experiment 2, Mark Brudnak, Mike Pozolo, Victor Paul, Syed Mohammad, Marc Compere, Et Al.
Publications
This paper describes a human-in-the-loop motion-based simulator interfaced to hybrid-electric power system hardware both of which were used to measure the duty cycle of a combat vehicle in a virtual simulation environment. The project discussed is a greatly expanded follow-on to the experiment published in [1]. This paper is written in the context of [1] and therefore highlights the enhancements. The most prominent of these enhancements is the integration (in real-time) of the Power & Electric System Integration Lab (P&E SIL) with a motion base simulator by means of a “long haul” connection over the Internet (a geographical distance of …
A Dyad Theory Of Hydrodynamics And Electrodynamics, Preston Jones
A Dyad Theory Of Hydrodynamics And Electrodynamics, Preston Jones
Publications
The dyadic calculus is developed in a form suitable for the description of physical relations in curved space. The 4-space equations of hydrodynamics and electrodynamics are constructed using this dyadic calculus. As a demonstration of the relationship between gravity and electrodynamics a time varying metric is shown to generate electromagnetic radiation.
Virgo’S Intracluster Globular Clusters As Seen By The Advanced Camera For Surveys, Benjamin F. Williams, Robin Ciardullo, Ted Von Hippel, Et Al.
Virgo’S Intracluster Globular Clusters As Seen By The Advanced Camera For Surveys, Benjamin F. Williams, Robin Ciardullo, Ted Von Hippel, Et Al.
Publications
We report the discovery of four candidate intracluster globular clusters (IGCs) in a single deepHST ACS field of the Virgo Cluster. We show that each cluster is roughly spherical, has a magnitude near the peak of the Virgo globular cluster luminosity function, has a radial profile that is best fitted by a King model, and is surrounded by an excess of point sources that have the colors and magnitudes of cluster red giant stars. Despite the fact that two of our IGC candidates have integrated colors redder than the mean of the M87 globular cluster system, we propose that …
Globalization And The Deepening Indian-U.S. Partnership In An Age Of Entrenched Anti-Americanism, Geoffrey Kain
Globalization And The Deepening Indian-U.S. Partnership In An Age Of Entrenched Anti-Americanism, Geoffrey Kain
Publications
“One of the topics often debated in the larger context of globalization is whether or not globalization is fundamentally a new-colonialist/neo-imperialist force (this view might be regarded as the Noam Chomsky school), or whether it is better represented as more of an open-access, competitive landscape on a truly global scale (this view might be regarded as the Thomas Friedman school)…”
Gaurav's Troubles, Geoffrey Kain
Gaurav's Troubles, Geoffrey Kain
Publications
“Gaurav’s troubles began when he was very young, actually before he had learned to walk. While removing a pot of hot oil from the stove, his mother had stumbled, sloshing some of the oil over the edge of the pot and splashing little Gaurav on his lower left leg and foot, and across the back of his left hand and arm…”
Heating Methods And Detection Limits For Infrared Thermography Inspection Of Fiber-Reinforced Polymer Composites, Jeff R. Brown, H. R. Hamilton
Heating Methods And Detection Limits For Infrared Thermography Inspection Of Fiber-Reinforced Polymer Composites, Jeff R. Brown, H. R. Hamilton
Publications
The use of fiber-reinforced polymer (FRP) composites to strengthen existing civil infrastructure is expanding rapidly. Many FRP systems used to strengthen reinforced concrete are applied using a wet lay-up method in which dry fibers are saturated on site and then applied to the surface. This research investigated using infrared thermography (IRT) as a nondestructive evaluation (NDE) tool for detecting air voids and epoxy-filled holes in FRP systems bonded to a concrete substrate. Four small-scale specimens with FRP thicknesses ranging from 1 to 4 mm (0.04 to 0.16 in.) containing fabricated defects were constructed and inspected in a laboratory setting. Three …
Lightning Signature Assessment To Forecast Tornado Formation, Mary Snow, Richard Snow, Nicole Kufa
Lightning Signature Assessment To Forecast Tornado Formation, Mary Snow, Richard Snow, Nicole Kufa
Publications
Recent research suggests that a maximum rate of lightning strikes occurs at least 15 to 20 minutes prior to tornado formation within a supercell storm. These maxima are associated with strengthening updrafts as they appear in radar measurements. An increase in lightning rates correlates with an increase of shear in the lower part of the storm. In combination with a strong updraft or downdraft, this shear can provide the ingredients for rotation and possibly a tornado. Polarity reversal of lightning around the time of tornado touchdown also has been examined. Thus, increasing lightning flash rates and reversal of lightning strike …
Multiphoton Response Of Retinal Rod Photoreceptors, Vasilios Alexiades, Harihar Khanal
Multiphoton Response Of Retinal Rod Photoreceptors, Vasilios Alexiades, Harihar Khanal
Publications
Phototransduction is the process by which light is converted into an electrical response in retinal photoreceptors. Rod photoreceptors contain a stack of (about 1000) disc membranes packed with photopigment rhodopsin molecules, which absorb the photons. We present computational experiments which show the profound effect on the response of the distances (how many discs apart) photons happen to be absorbed at. This photon-distribution effect alone can account for much of the observed variability in response.
Book Review: Conquest In Cyberspace: National Security And Information Warfare, Gary C. Kessler
Book Review: Conquest In Cyberspace: National Security And Information Warfare, Gary C. Kessler
Publications
This document is Dr. Kessler's review of Conquest in Cyberspace: National Security and Information Warfare, by Martin C. Libicki. Cambridge University Press, 2007. ISBN 978-0-521-69214-4
Book Review: No Place To Hide, Gary C. Kessler
Book Review: No Place To Hide, Gary C. Kessler
Publications
This document is Dr. Kessler's review of No Place to Hide, by Robert O'Harrow, Jr. Free Press, 2006. ISBN 0-7432-8705-3.
Forensic Analysis Of Xbox Consoles, Paul Burke, Philip Craiger
Forensic Analysis Of Xbox Consoles, Paul Burke, Philip Craiger
Publications
Microsoft’s Xbox game console can be modified to run additional operating systems, enabling it to store gigabytes of non-game related files and run various computer services. Little has been published, however, on procedures for determining whether or not an Xbox console has been modified, for creating a forensic duplicate, and for conducting a forensic investigation. Given the growing popularity of Xbox systems, it is important to understand how to identify, image and examine these devices while reducing the potential of corrupting the media. This paper discusses Xbox forensics and provides a set of forensically-sound procedures for analyzing Xbox consoles.
Factors Affecting One-Way Hashing Of Cd-R Media, Christopher Marberry, Philip Craiger
Factors Affecting One-Way Hashing Of Cd-R Media, Christopher Marberry, Philip Craiger
Publications
While conducting a validation study of proficiency test media we found that applying the same hash algorithm against a single CD using different forensic applications resulted in different hash values. We formulated a series of experiments to determine the cause of the anomalous hash values. Our results suggest that certain write options cause forensic applications to report different hash values. We examine the possible consequences of these anomalies in legal proceedings and provide best practices for the use of hashing procedures.
Data Mining Methods Applied To Flight Operations Quality Assurance Data: A Comparison To Standard Statistical Methods, Alan J. Stolzer, Carl Halford
Data Mining Methods Applied To Flight Operations Quality Assurance Data: A Comparison To Standard Statistical Methods, Alan J. Stolzer, Carl Halford
Publications
"In a previous study, multiple regression techniques were applied to Flight Operations Quality Assurance-derived data to develop parsimonious model(s) for fuel consumption on the Boeing 757 airplane. The present study examined several data mining algorithms, including neural networks, on the fuel consumption problem and compared them to the multiple regression results obtained earlier. Using regression methods, parsimonious models were obtained that explained approximately 85% of the variation in fuel flow. In general data mining methods were more effective in predicting fuel consumption. Classification and Regression Tree methods reported correlation coefficients of .91 to .92, and General Linear Models and Multilayer …
Measuring Faculty Perceptions Of Blackboard Using The Technology Acceptance Model, Leila Halawi, Richard Mccarthy
Measuring Faculty Perceptions Of Blackboard Using The Technology Acceptance Model, Leila Halawi, Richard Mccarthy
Publications
Web-based education offers the combination of self-paced learning and interactivity. We are just now beginning to empirically assess the differences between online education and traditional classroom based instruction. The Technology Acceptance Model (TAM) has been widely used in Information Systems research to analyze user perceptions of technology. This paper describes the results of an empirical study of faculty perception of Blackboard usage, utilizing TAM as its theoretical basis.