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Laurel, MD, United States

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. Source

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. Source

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. Source

Avritzer A.,Siemens AG | Cole R.G.,JHU Applied Physics Laboratory | Weyuker E.J.,AT&T
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. Source

Rizk C.G.,JHU Applied Physics Laboratory
Johns Hopkins APL Technical Digest (Applied Physics Laboratory) | Year: 2010

Flexible Readout and Integration Sensors (FRIS) were introduced as a new class of imaging sensor arrays optimized for air and missile defense. The all-digital event-based readout sensor achieved significant flexibility in windowing or arbitrary pixel access at significantly high rates. The sensor also eliminated the traditional analog shift register and Nyquist rate A/D converter. It removed the upper limit on the frame rate and the conventional limits of electron well capacitance. Source

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