JHU Applied Physics Laboratory
JHU Applied Physics Laboratory
Goldrich L.,JHU Applied Physics Laboratory |
Hamer S.,JHU Applied Physics Laboratory |
Selby C.,Rose - Hulman Institute of Technology |
Longstaff T.,National Security Agency
Proceedings of the Annual Hawaii International Conference on System Sciences | Year: 2013
Cybersecurity systems are comprised of a wide variety of interconnected systems. If these individual systems are not sufficiently designed and implemented to work well when integrated, additional opportunities for adversaries to hide and attack are created. To better enable researchers to broaden their scope and work together, they must be able to explore research in other areas and work across disciplines to create standards for communication and systems that work synergistically. This paper describes Department of Homeland Security (DHS) Assistant for Research and Development Tracking and Technology Transition (DART3), a web-based semantic tool and repository designed to capture US federally funded research and development (R&D) project descriptions and R&D requirements to facilitate technology transitions. © 2012 IEEE.
Lorenz R.D.,JHU Applied Physics Laboratory |
Tokano T.,University of Cologne |
Newman C.E.,Ashima Research
Planetary and Space Science | Year: 2012
We use two independent General Circulation Models (GCMs) to estimate surface winds at Titan's Ligeia Mare (78° N, 250° W), motivated by a proposed mission to land a floating capsule in this ∼500 km hydrocarbon sea. The models agree on the overall magnitude (∼0.51 m/s) and seasonal variation (strongest in summer) of windspeeds, but details of seasonal and diurnal variation of windspeed and direction differ somewhat, with the role of surface exchanges being more significant than that of gravitational tides in the atmosphere. We also investigate the tidal dynamics in the sea using a numerical ocean dynamics model: assuming a rigid lithosphere, the tidal amplitude is up to ∼0.8 m. Tidal currents are overall proportional to the reciprocal of depth - with an assumed central depth of 300 m, the characteristic tidal currents are ∼1 cm/s, with notable motions being a slosh between Ligeia's eastern and western lobes, and a clockwise flow pattern. We find that a capsule will drift at approximately one tenth of the windspeed, unless measures are adopted to augment the drag areas above or below the waterline. Thus motion of a floating capsule is dominated by the wind, and is likely to be several km per Earth day, a rate that will be readily measured from Earth by radio navigation methods. In some instances, the wind vector rotates diurnally such that the drift trajectory is epicyclic. © 2011 Elsevier Ltd. All rights reserved.
Troshichev O.,Arctic and Antarctic Research Institute |
Stauning P.,Danish Meteorological Institute |
Liou K.,JHU Applied Physics Laboratory |
Reeves G.,Los Alamos National Laboratory
Advances in Space Research | Year: 2011
The relationships between the magnetic disturbance onsets, aurora dynamics and particles injections at the geostationary orbit have been analyzed in detail for 25 sawtooth substorms. It is shown that inconsistency between the above signatures of the substorms onset is typical of the powerful sawtooth substorms, unlike the isolated ("classical") magnetospheric substorms. The distinguishing feature of the aurora in case of saw-tooth substorms is permanently high level of auroral activity irrespective of the magnetic disturbance onsets and the double oval structure of the aurora display. The close relationship between the aurora behavior and the particle injections at geostationary orbit is also broken. The conclusion is made, that the classical concept of the substorm development, put forward by Akasofu (1964) for isolated substorms, is not workable in cases of the sawtooth disturbances, when the powerful solar wind energy pumping into the magnetosphere provides a permanent powerful aurora particle precipitation into the auroral zone. © 2010 COSPAR. Published by Elsevier Ltd. All rights reserved.
Savage C.J.,Brigham Young University |
Radebaugh J.,Brigham Young University |
Christiansen E.H.,Brigham Young University |
Lorenz R.D.,JHU Applied Physics Laboratory
Icarus | Year: 2014
Analysis of large-scale morphological parameters can reveal the reaction of dunes to changes in atmospheric and sedimentary conditions. Over 7000 dune width and 7000 dune spacing measurements were obtained for linear dunes in regions across Saturn's moon Titan from images T21, T23, T28, T44 and T48 collected by the Synthetic Aperture RADAR (SAR) aboard the Cassini spacecraft in order to reconstruct the aeolian surface history of Titan. Dunes in the five study areas are all linear in form, with a mean width of 1.3. km and mean crest spacing of 2.7. km, similar to dunes in the African Saharan and Namib deserts on Earth. At the resolution of Cassini SAR, the dunes have the morphology of large linear dunes, and they lack evidence for features of compound or complex dunes. The large size, spacing and uniform morphology are all indicators that Titan's dunes are mature features, in that they have grown toward a steady state for a long period of time. Dune width decreases to the north, perhaps from increased sediment stabilization caused by a net transport of moisture from south to north, or from increased maturity in dunes to the south. Cumulative probability plots of dune parameters measured at different locations across Titan indicate there is a single population of intermediate-to-large-sized dunes on Titan. This suggests that, unlike analogous dunes in the Namib and Agneitir Sand Seas, dune-forming conditions that generated the current set of dunes were stable and active long enough to erase any evidence of past conditions. © 2013 Elsevier Inc.
VanderNoot V.A.,Sandia National Laboratories |
Renzi R.F.,Sandia National Laboratories |
Mosier B.P.,JHU Applied Physics Laboratory |
Van De Vreugde J.L.,Sandia National Laboratories |
And 2 more authors.
Electrophoresis | Year: 2010
Field-deployable detection technologies in the nation's water supplies have become a high priority in recent years. The unattended water sensor is presented which employs microfluidic chip-based gel electrophoresis for monitoring proteinaceous analytes in a small integrated sensor platform. The instrument collects samples directly from a domestic water flow. The sample is then processed in an automated microfluidic module using in-house designed fittings, microfluidic pumps and valves prior to analysis via Sandia's μChemLab™ module, which couples chip-based electrophoresis separations with sensitive LIF detection. The system is controlled using LabVIEW software to analyze water samples about every 12 min. The sample preparation, detection and data analysis has all been fully automated. Pressure transducers and a positive control verify correct operation of the system, remotely. A two-color LIF detector with internal standards allows corrections to migration time to account for ambient temperature changes. The initial unattended water sensor prototype is configured to detect protein biotoxins such as ricin as a first step toward a total bioanalysis capability based on protein profiling. The system has undergone significant testing at two water utilities. The design and optimization of the sample preparation train is presented with results from both laboratory and field testing. © 2010 Wiley-VCH Verlag GmbH & Co. KGaA.
Lorenz R.,JHU Applied Physics Laboratory
IEEE Aerospace Conference Proceedings | Year: 2013
Desert dust devil phenomena on Earth and Mars are reviewed, and progress in studying them with novel unattended field sensors, and with timelapse imaging, is described. These new datasets present data analysis challenges which are familiar in other tracking/target identification applications. © 2013 IEEE.
Avritzer A.,Siemens AG |
Cole R.G.,JHU Applied Physics Laboratory |
Weyuker E.J.,AT and T Labs Research
Journal of Systems and Software | Year: 2010
In this paper we describe several methods for detecting the need for software rejuvenation in mission critical systems that are subjected to worm infection, and introduce new software rejuvenation algorithms. We evaluate these algorithms' effectiveness using both simulation studies and analytic modeling, by assessing the probability of mission success. The system under study emulates a Mobile Ad-Hoc Network (MANET) of processing nodes. Our analysis determined that some of our rejuvenation algorithms are quite effective in maintaining a high probability of mission success while the system is under explicit attack by a worm infection. © 2009 Elsevier Inc.
Lorenz R.D.,JHU Applied Physics Laboratory
IEEE Aerospace Conference Proceedings | Year: 2010
Dust devils are dry convective vortices that loft dust into the air, often a nuisance for outdoor activities and occasionally responsible for structural damage and fatal aircraft accidents. 12They are also the most prominent dynamic phenomena observed on the surface of Mars, where they influence the climate by acting as the principal mechanism of dust-raising. Atmospheric dust, and its removal by dust devils from solar panels, can also significantly impact the operation of spacecraft on the Martian surface. However, many aspects of dust devil behavior and properties are not well-understood. Here I report progress towards obtaining robust statistics on dust devil properties, and their 2-dimensional horizontal structure, using arrays of small dataloggers and wireless motes. I additionally report some ancillary observations using a thermal camera, and timelapse optical imagery derived from inexpensive consumer digital cameras. ©2010 IEEE.
Boyd-Graber J.,University of Maryland College Park |
Glasgow K.,JHU Applied Physics Laboratory |
Zajac J.S.,University of Maryland College Park
Proceedings of the ASIST Annual Meeting | Year: 2013
Spoilers-critical plot information about works of fiction that "spoil" a viewer's enjoyment-have prompted elaborate conventions on social media to allow readers to insulate themselves from spoilers. However, these solutions depend on the conscientiousness and rigor of Internet posters and are thus an imperfect system. We create an automatic alternative that could alert users when a piece of text contains a spoiler. An automated spoiler detector serves not only as an additional protection against spoilers, but it also contributes to important problems in computational linguistics. We develop a new dataset of spoilers gathered from social media and create automatic classifiers using machine learning techniques. After establishing baseline performance using lexical features, we develop metadata-based features that substantially improve performance on the spoiler detection task.
Agency: Department of Defense | Branch: Navy | Program: STTR | Phase: Phase I | Award Amount: 80.00K | Year: 2015
We propose the design and development of LCS radar modeling for training a radar modeling engine that capture the effects of environment, weather, jamming/interference and operator actions on radar display. The purpose of this engine is to reduce or eli