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The localization of an RF transmitter by a distributed set of RF receivers has important application to the Navy. We report the results of a transmitter localization experiment done at the Naval Research Laboratory. A distributed sensor network was implemented on GNU radio and field-tested. The network locates target emitters using differences in received powers between sensors. We discuss the localization algorithm and the likely sources of error associated with it. We review simulated and experimental results consistent with our interpretations of the error sources, and we suggest methods for dealing with these errors in future iterations of the sensor network., The original document contains color images. Prepared in collaboration with KEYW Corporation, Hanover, MD, Catholic University of America, Washington, D.C., and University of Louisiana at Lafayette, Lafayette, LA.

Distributed sensor networks often call for bursty, high data rate communications over long distances and fluctuating channels. A waveform for such a scenario would ideally be wideband to mitigate frequency selective fading, have data multiplexed into separate streams for high data rate, have long symbol times to mitigate multipath, and have a constant amplitude over time for non-linear amplification. These requirements are uniquely served by constant envelope OFDM. We describe the use-cases, theory, and successful implementation of such a waveform via the GNU radio framework on Ettus software-defined radios. We measure the bit error performance of the link as a function of channel quality and compare this performance to simulations of the link., The original document contains color images. Prepared in collaboration with KEYW Corporation, Hanover, MD.

Mode 2 internal waves have been repeatedly observed in two separate bathymetry zones on the New Jersey (USA) continental shelf. In the first zone, the upslope propagating mode 2 internal waves were detected in a 15 km range interval shoreward of the shelf break in water depths ranging between 90 and 150 m. They were formed in conjunction with shoreward propagating internal tides and exhibited both nonlinear and linear characteristics. In the second zone, they were detected in 60 to 80 m water depths and appeared to be formed by flow over the local bathymetry. Simulations using the Shen Non-hydrostatic Model for Coastal Oceans (SNMCO) replicated the observed coupled internal tide and mode 2 internal wave generation process and separately the formation of mode 2 internal waves by flow over local bathymetry variability. The observations expand the knowledge base regarding the time window (fall, 7 days before and including neap tidal conditions), spatial distributions, packet evolution and conditions under which mode 2 internal waves are generated on the continental shelf., The original document contains color images.

We investigate the feasibility of using optically generated channels of reduced air density to provide trajectory correction (guiding) for a supersonic projectile. It is shown that the projectile experiences a force perpendicular to its direction of motion as one side of the projectile passes through a channel of reduced air density. A single channel of reduced air density can be generated by the energy deposited from filamentation of an intense laser pulse. We propose changing the laser pulse energy from shot-to-shot to build longer effective channels. Current femtosecond lasers systems with multi-millijoules pulses could provide trajectory correction of several meters on 5 km trajectories for sub-kilogram projectiles traveling at Mach 2 to Mach 3., The original document contains color images.

The Autonomous Locator of Thermals (ALOFT) algorithm goal was to develop an algorithm which could exploit naturally occurring convective thermal updrafts for extending the endurance of an unmanned aerial vehicle (UAV). A commercial off-the-shelf SBXC sailplane was outfitted as a UAV and used for more than 100 test flights of the ALOFT algorithm, with a nominal endurance of 3 minutes after a winch-launch to 100 meters. A notable success was unofficially breaking the cross-country soaring goal-and-return world record by flying 60.4 total miles over approximately 4.55 hours. Best endurance demonstrated by the algorithm was 5.3 hours and best range demonstrated by the algorithm was 70.47 miles. This report documents the final ALOFT software algorithms developed, to capture the most important implementation details and mathematical formulas. Specifically, the soaring algorithm is divided into four major functions: reading state data from the autopilot, identifying the position and other characteristics of a nearby thermal, making soaring behavioral decisions, and sending soaring commands to the autopilot., The original document contains color images.

An investigation was carried out to characterize the effect of crack tip stress concentration factor (Kt) on fracture resistance of various aluminum alloys and a steel in vacuum environment. The materials investigated were peakaged 7075-T651, overaged 7075-T7351, 5083-H131, fully sensitized Al 5083 (175 C/240 hrs), 2024-T351, and AISI 4340 steel. Fracture mechanics wedge-opening-load (WOL) specimens were used in the current study. The test environment was vacuum so that the baseline fracture resistance of the material without the influence of environment could be determined. The results indicate: (1) in all alloys, the fracture resistance is highest for blunt-notches (smaller Kt), and is lowest for fatigue-sharpened precracked notches (larger Kt); (2) the fracture resistance decreases linearly as Kt increases; (3) at similar Kt levels, AISI 4340 steel exhibits fracture resistance about twice higher than those of the aluminum alloys; (4) the peakaged 7075-T651 and overaged 7075-T7351 have comparable fracture resistance; (5) the fracture resistance of 2024-T351 alloy is higher than 7075 alloys; (6) the fracture resistances of as-received 5083-H131 (5083R) and sensitized 5083S (175 C/240 hrs) are comparable in all Kt, except at the smallest Kt = 3 where the fracture resistance of 5083R is higher; and (7) the fracture paths are transgranular and the fracture mode is ductile void coalescence in all cases, irrespective of the stress concentration factor., The original document contains color images.

An investigation was carried out to characterize the effects of environment (including [NaCl] concentration) and load ratio on fatigue crack growth kinetics of HY-80 and HY-130 steels. Fracture mechanics wedge-opening-load (WOL) specimens oriented in the longitudinal direction (LT) were used in the current study. The test environments were vacuum, ambient air, and saltwater with [NaCl] concentrations ranging from 0.1 to 15%. Three load ratios, corresponding to R = 0.1, R = 0.5, and R = 0.85, were examined. The results indicate: (1) the fatigue crack growth rates and fatigue crack growth threshold, Kth, for HY-80 steel and HY-130 steel are comparable at similar stress ratios in each of the three test environments (vacuum, ambient air, and 1% NaCl solution); (2) in the low stress intensity region, the fatigue crack growth rates of both HY-80 steel and HY-130 steel are higher and Kth are lower at a high load ratio than those obtained at lower load ratios; (3) the fatigue crack growth rates of HY-80 steel and HY-130 steel obtained in ambient air and in 3.5% NaCl solution are comparable and are significantly higher than those obtained in vacuum; (4) the fatigue crack growth responses of HY-130 steel are not affected by the change in [NaCl] concentration; and (5) cathodic protection of HY-130 steel in saltwater does not lower its corrosion-fatigue cracking resistance., The original document contains color images.

An investigation was carried out to characterize the effect of sensitization (or aging), environment (including [NaCl] concentration), and load ratio on fatigue crack growth and stress-corrosion cracking (SCC) of Al 5083 alloy. Both low and high load ratios, corresponding to R = 0.1 and R = 0.85 were examined. The results indicate: (1) fully sensitized Al 5083 has very low high stress-ratio (at R = 0.85) corrosion-fatigue (CF) threshold stress intensity ( Kth) and SCC threshold (K1SCC) in saltwater; (2) the as-received Al 5083-H131 has good CF and SCC resistance; (3) at 175 C aging temperature, high stress ratio Kth and K1SCC in saltwater decrease with increasing aging time up to about 240 hours; aging times longer than 240 hours produce little additional degradation; (4) sensitization has no effect on fatigue crack growth at low stress ratio of R = 0.1 in any environment, and no effect at any stress ratio in vacuum and in ambient air; (5) both high stress ratio Kth and K1SCC are influenced by [NaCl] concentration, higher [NaCl] results in a lower high stress ratio Kth and K1SCC., The original document contains color images. Prepared in collaboration with the Center for Corrosion Science and Engineering, Chemistry Division, NRL, Washington, DC.

A detailed understanding of solar irradiance and its variability at extreme ultraviolet (EUV) wavelengths is required to model thermospheric density and to specify and forecast satellite drag. Current operational models rely on forecasts of proxies for solar activity based on autoregression. The forecasts from these models generally degrade to climatology after only a few days. Solar magnetic fields are ultimately responsible for variations in the EUV irradiance. The evolution of solar magnetic fields is well understood and results from a combination of solar rotation, diffusion, meridional flow, and magnetic flux emergence. In this presentation we review the current state of autoregressive proxy models and compare their forecast skill against new activity models based on magnetic flux transport., In the Advanced Maui Optical and Space Surveillance Technologies (AMOS) Conference, 9-12 Sep 2014, Maui, HI.

Atmospheric drag is the largest source of error in the prediction of trajectories of most objects in low-Earth orbit, and solar variability is the largest source of error in upper atmospheric density forecasts. There is thus a need to accurately propagate solar forecast uncertainty to atmospheric density uncertainty and thence to satellite position uncertainty. Furthermore, the collective position uncertainty of the low-Earth Orbit (LEO) population determines the frequency of conjunctions that must be assessed in order to avoid collisions. To maintain Space Situational Awareness of the growing LEO population, the number of conjunctions must be kept at a manageable level to avoid being overwhelmed by false alarms. This criterion can be used to define solar and atmospheric forecast accuracy requirements. In this paper, we examine how solar forecast errors grow with increasing forecast time, and how this uncertainty maps to atmospheric density uncertainty as a function of altitude. We then develop analytical approximations of the mapping from density uncertainty to in-track position uncertainty, as a function of perigee height, orbital eccentricity, ballistic coefficient, background atmospheric conditions, and forecast time. Finally, we estimate the conjunction frequency between operational LEO satellites and the entire LEO population (separately considering objects larger than 10 cm and objects larger than 1 cm), based on the statistical distributions of the key orbital parameters (perigee height, eccentricity, inclination and ballistic coefficient) and assumed solar and density forecast uncertainties. 1, In the Advanced Maui Optical and Space Surveillance Technologies (AMOS) Conference, 9-12 Sep 2014, Maui, HI. Supported in part by ONR.

Photons of the appropriate energy can induce photofission in fissile material. We are investigating the applicability of this mechanism, using photons from bremsstrahlung, for long-range ( 100 m) detection of fissile material using high-power ( 1 TW), pulsed technology so called intense, pulsed active detection. In this report, we describe the results of laboratory, proof-of-principle experiments, supported by computations and analyses, in which a single pulse of 8-MeV endpoint bremsstrahlung from the Naval Research Laboratory Mercury pulsed-power generator (200-kA peak current, 50-ns pulse width) induces photofission in depleted uranium. Fission products are measured using He-3 proportional counters, and plastic (BC408), sodium-iodide (NaI:Tl), and bismuth-germinate-oxide scintillators. Prompt neutrons, delayed neutrons, and delayed gamma-rays from the induced photofission are measured unambiguously. Delayed neutron and gamma-ray measurements are also carried out with various thicknesses of low- and high-atomic-number materials attenuating the bremsstrahlung and fission signatures. Results of simulations and analyses carried out in support of the experiments are in agreement with the measurements. In addition, we demonstrate that relatively simple variations of the diode geometry can increase the efficiency of inducing fissions three-fold over the original geometry. These geometry changes cause the electron beam to be more normally incident onto the tantalum converter and thereby increase the forward-directed bremsstrahlung intensity without changing the driving, electrical power pulse. The results of this work and future directions for this research are presented in this report., The original document contains color images. Sponsored in part by Office of Naval Research. Prepared in collaboration with Naval Research Laboratory, Space Sciences Division, Washington, DC, Engility, Inc., Chantilly, VA, and Idaho State University, Idaho Falls, ID.

A new method has been developed to analyze high-resolution spectral data of the solar photosphere and chromosphere. The data format is a two-dimensional (2-D) time-series of images. The method uses emission or absorption lines in the intensity and polarization data (Stokes parameters). Each pixel contains quantitative information on the spectral profiles of selected lines, such as the line width, degree of asymmetry, and peakedness. The 2-D time-series is first averaged in time pixel-by-pixel. A derivative time-series is constructed such that each image in the time-series is characterized by the pixel-by-pixel deviations from the average. The pixel fluctuation distribution (PFD) function is constructed and its statistical properties are calculated. Such properties including the mean, variance, skewness, and kurtosis are computed as functions of time and are used to precisely quantify temporal variations in the observed spectral data. In this work, the method is applied to photospheric absorption lines (Fe I 6301.5 and 6302.5 ) from quiet-Sun regions and active regions on the solar photosphere, obtained by the vector spectromagnetograph (VSM) of the Synoptic Optical Long-term Investigations of the Sun (SOLIS) of the National Solar Observatory (NSO)., The original document contains color images.

A series of coupled measurements was made at the Naval Air Station North Island (NASNI) Installation Restoration Site 5, Unit 2 during July and August 2013. Preliminary samples were taken in March 2013. Coupled measurements included CO2 respiration rate, proportion of the CO2 attributable to chlorinated hydrocarbon (CH) mineralization and a zone of influence (ZOI) model. This coupling led to calculating CH degradation per unit time per unit area. These coupled measurements represent the first analysis where carbon is followed from contaminant to final degradation product (CO2) directly without need for inference or lines of evidence. In order to determine a mass removal for this study, the average contaminant mineralization rate (0.673 g C m-3 d-1) was multiplied by the total area within the sampling grid (1,225 m2) then multiplied by the ZOI depth to give the total carbon mass removal from the CH pool: 14.5 g C d-1. The wells on site are screened at the groundwater:vadoze zone interface and the vertical ZOI characteristics are likely very different above and below the water table (vadoze versus saturated zone). However, if the assumption is made that the entire surface soil lens (sandy silt) to a depth of approximately 3 meters has similar CH degradation rates, an optimistic estimate of 246 g C d-1 over the entire sampled site area can be calculated. In terms of dissolved CH, an estimate of 0.100 g CH carbon L-1 was assumed based on reported values (from 2009). Over the site, within the ZOI, residence time for CH averaged just over 4 years, assuming no additional input (desorbing from soils). At the lowest measured turnover rates, residence time was calculated at 2,400 years and the highest measured rate, 11 months., The original document contains color images. Prepared in collaboration with Oregon State University, Corvallis, OR.

Robots can be important additions to human teams if they improve team performance by providing new skills or improving existing skills. However, to get the full benefits of a robot the team must trust and use it appropriately. We present an agent algorithm that allows a robot to estimate its trustworthiness and adapt its behavior in an attempt to increase trust. It uses case-based reasoning to store previous behavior adaptations and uses this information to perform future adaptations. We compare case-based behavior adaptation to behavior adaptation that does not learn and show it significantly reduces the number of behaviors that need to be evaluated before a trustworthy behavior is found. Our evaluation is in a simulated robotics environment and involves a movement scenario and a patrolling/threat detection scenario., Published in Proceedings of the 22nd International Conference on Case-Based Reasoning Held 29 Sep-1 Oct 2014 in Cork, Ireland, p125-139.

We present SET-PR, a novel case-based plan recognition algorithm that is tolerant to missing and misclassified actions in its input action sequences. SET-PR uses a novel representation called action sequence graphs to represent stored plans in its plan library and a similarity metric that uses a combination of graph degree sequences and object similarity to retrieve relevant plans from its library. We evaluated SET-PR by measuring plan recognition convergence and precision with increasing levels of missing and misclassified actions in its input. In our experiments, SET-PR tolerated 20%-30% of input errors without compromising plan recognition performance., Published in Proceedings of the 22nd International Conference on Case-Based Reasoning, Held 29 Sep-1 Oct 2014, in Cork, Ireland, p495-510.

The SpinSat flight is a small satellite mission proposed by the Naval Research Laboratory and Digital Solid State Propulsion \201DSSP\202 LLC to demonstrate and characterize the on-orbit performance of electrically controlled solid propellant technology in space. Launch is expected in summer of 2014. This is an enabling technology for the small satellite community that will allow small satellites to perform maneuvers. The mission consists of a spherical spacecraft fitted with Electrically Controlled Solid Propellant thrusters and retro-reflectors for satellite laser ranging \201SLR\202. The spacecraft will be deployed from the International Space Station. This paper presents a mission overview, ground truth characterization and unique SSA observation opportunities of the mission., Presented at the Advanced Maui Optical and Space Surveillance Technologies (AMOS) Conference, 9-12 Sep 2014, Maui, HI.

The intercalation of various atomic species, such as hydrogen, to the interface between epitaxial graphene (EG) and its SiC substrate is known to significantly influence the electronic properties of the graphene overlayers. Here, we use high-resolution X-ray reflectivity to investigate the structural consequences of the hydrogen intercalation process used in the formation of quasi-free-standing (QFS) EG/SiC(0001). We confirm that the interfacial layer is converted to a layer structurally indistinguishable from that of the overlying graphene layers. This newly formed graphene layer becomes decoupled from the SiC substrate and, along with the other graphene layers within the film, is vertically displaced by 2.1 Angstroms . The number of total carbon layers is conserved during the process, and we observe no other structural changes such as interlayer intercalation or expansion of the graphene d-spacing. These results clarify the under-determined structure of hydrogen intercalated QFS-EG/SiC(0001) and provide a precise model to inform further fundamental and practical understanding of the system., Published in Applied Physics Letters, v105, 161602, 2014.

An investigation was carried out to characterize the effect of aging, environment (include [NaCl] concentration), and load ratio on fatigue crack growth kinetics of Al 7075 alloy. The materials investigated were peakaged Al 7075-T651 and overaged Al 7075-T7351. The results indicate: (1) the fatigue crack growth rates and fatigue crack growth threshold, Kth, for Al 7075-T651 and Al 7075-T7351 are comparable at similar stress ratios in each of the three test environments (vacuum, ambient air, and 1% NaCl solution); (2) irrespective of Al 7075 aging conditions and stress ratios, the fatigue crack growth rates are lowest in vacuum, followed by those in ambient air, and are highest in 1% NaCl; (3) for both Al 7075-T651 and Al 7075-T7351, the fatigue crack growth rates initially increase rapidly when [NaCl] increases from 0.001 to 1% and then remain unchanged when [NaCl] further increases from 1 to 15%; and (4) for both Al 7075-T651 and Al 7075-T7351, the fatigue crack growth rates are higher at higher stress ratio in all three environments and the Kth progressively decreases as the load ratio increases., The original document contains color images.

Differences in the Raman signatures of fresh and environmentally aged explosives could allow a warfighter who has identified the presence of trace amounts of explosives to ascertain if the material detected is the remnant of a previous event that has been exposed to the environment for a period of time or is an indication of a current threat. To determine if environmental exposure alters Raman signatures, we examined the signatures of fresh and artificially aged TNT at multiple illumination wavelengths between 420 and 620 nanometers. While the macroscopic differences (such as peak height and line ratios) between the Raman signatures of the fresh and aged samples are either too small or not reproducible enough to use for differentiation, we find that by utilizing an algorithm based on the Pearson correlation coefficient, differentiation can be made between the fresh and aged variants at an accuracy of 82%., The original document contains color images. Prepared in collaboration with Research Support Instruments, Lanham, MD.

We make direct observations of localized light absorption in a single nanostructure irradiated by a strong femtosecond laser field, by developing and applying a technique that we refer to as plasma explosion imaging. By imaging the photoion momentum distribution resulting from plasma formation in a laser-irradiated nanostructure, we map the spatial location of the highly localized plasma and thereby image the nanoscale light absorption. Our method probes individual, isolated nanoparticles in vacuum, which allows us to observe how small variations in the composition, shape, and orientation of the nanostructures lead to vastly different light absorption. Here, we study four different nanoparticle samples with overall dimensions of 100 nm and find that each sample exhibits distinct light absorption mechanisms despite their similar size. Specifically, we observe subwavelength focusing in single NaCl crystals, symmetric absorption in TiO2 aggregates, surface enhancement in dielectric particles containing a single gold nanoparticle, and interparticle hot spots in dielectric particles containing multiple smaller gold nanoparticles. These observations demonstrate how plasma explosion imaging directly reveals the diverse ways in which nanoparticles respond to strong laser fields, a process that is notoriously challenging to model because of the rapid evolution of materials properties that takes place on the femtosecond time scale as a solid nanostructure is transformed into a dense plasma., Published in ACS Nano, v8 n9 p8810-8818, 2014. Sponsored in part by NRL.

Predictions of the amount of water thrown upward from shallow depth explosions are presented in support of a new water barrier concept for the protection of Riverine vessels. The predictions are obtained using a model based on a generalized formulation of hydrodynamics using an incompressible liquid assumption, which has been previously validated on a variety of applications including water plume predictions. Depending on both the charge weight and initial depth, this study presents estimates for the Effective Water Length (EWL) values at heights and time intervals relevant for riverine vessel protection from Rocket Propelled Grenade (RPG) attacks., NDIA 2014 Warheads & Ballistics Symposium, held at Naval Postgraduate School, Monterey, CA, on 4-7 August 2014.

Microbial fuel cells (MFCs) have been the focus of substantial research interest due to their potential for long-term, renewable electrical power generation via the metabolism of a broad spectrum of organic substrates, although the low power densities have limited their applications to date. Here, we demonstrate the potential to improve the power extraction by exploiting biogenic inorganic nanoparticles to facilitate extracellular electron transfer in MFCs. Simultaneous short-circuit current recording and optical imaging on a nanotechnology-enabled platform showed substantial current increase from Shewanella PV-4 after the formation of cell/iron sulfide nanoparticle aggregates. Detailed characterization of the structure and composition of the cell/ nanoparticle interface revealed crystalline iron sulfide nanoparticles in intimate contact with and uniformly coating the cell membrane. In addition, studies designed to address the fundamental mechanisms of charge transport in this hybrid system showed that charge transport only occurred in the presence of live Shewanella, and moreover demonstrated that the enhanced current output can be attributed to improved electron transfer at cell/electrode interface and through the cellular networks. Our approach of interconnecting and electrically contacting bacterial cells through biogenic nanoparticles represents a unique and promising direction in MFC research and has the potential to not only advance our fundamental knowledge about electron transfer processes in these biological systems but also overcome a key limitation in MFCs by constructing an electrically connected, three-dimensional cell network from the bottom-up., Published in Nano Letters, v14 p6737-6742, 13 Oct 2014. Prepared in collaboration with the Department of Chemistry and Chemical Biology and Division of Engineering and Applied Sciences, Harvard University, Cambridge, Ma, and the CAS Key Laboratory of Molecular Nanostructure and Nanotechnology, Institute of Chemistry, Chinese Academy of Sciences, Beijing. Sponsored in part by AFOSR.

The Naval Research Laboratory (NRL) designed the Automatic Identification System (AIS) Collection and Reach-back System (ACRBS) to address a critical shortfall in the ability of the Military Sealift Command (MSC) to securely obtain and share its MSC ship position data along with the AIS data from all other surface contacts within AIS range (VHF) of the MSC ship. This document describes the NRL's design, assembly, and configuration of the ACRBS for the MSC. This document also provides technical information that is necessary to install ACRBS on a MSC host vessel., Prepared in collaboration with Protasis Inc., Alexandria, VA; Systems Engineering Associates International Inc., Melbourne Beach, FL; Comparative Innovations, LLC, White Plains, MD. Sponsored in part by USTRANSCOM. The original document contains color images.

Ocean Data Assimilation (DA) systems are tools to synthesize ocean observation data using the numerical ocean models, and widely applied as the primary method for transforming the data into information which can be used effectively by society. Conversely, the capacity of ocean DA systems inevitably depends on the extent to which the observing system satisfies the requirements of the DA systems. If an observing system does not satisfy these requirements, the system cannot provide effective information to society, which implies observational data are abandoned without being converted into effective information. Thus, it is essential for observing systems to satisfy the requirements of the DA systems. Moreover, quantifying the impacts of observational data on products of the systems is equivalent to evaluating the impact of the observations on society.

The shock-associated noise characteristics of an underexpanded jet at three jet temperatures were investigated using large-eddy simulations (LES). The impact of shock cells on the flow field and near- and far-field noise characteristics were examined. The impact of shock-associated noise is confined to one and a half jet core length in the near field. The near-field shift of the shock-associated peak frequency matches well with the inverse of the shock-cell size, indicating that the variation of the shock-cell size is largely responsible for this shift. In the far field, the variation of the shock-associated peak frequency agrees well with the available empirical model over a large range of the radiation angle, but the model under-predicts the fast increase near the end of the shock-associated noise region. In addition, the distributed nature of the shock-associated noise source impacts the far-field noise characteristic if the distance is not sufficiently large. Heating decreases the shock-cell impact on the total noise, but the heating impact on the shock-associated noise level in the upstream direction is opposite to that in the downstream direction. On the other hand, heating greatly increases the mixing noise, reducing the difference between the shock-containing jets and the shock-free jets., The original document contains color images.

This document reviews exploratory work to design, build, and test a table-top sized tungsten particle dispenser. A small canister and dispenser system within a vacuum bell jar is described to provide qualitative and quantitative observations of the dispensed particle stream. We selected tungsten carbide spheres and irregular tungsten powders all under 100 microns, driven by previous work. That work investigated the benefits of identical spherical particles, approximately 30 microns, filling an orbiting ring about the Earth to enhance drag, causing small pieces of orbital debris to enter the atmosphere. Using only gas or a gas-driven piston to propel the particles, many tests showed that increasing pressure yielded increasing stream velocity and higher velocity in vacuum than in air. Speed goals could be achieved and controlled, but because the speed and mass flow rate were directly linked, an abrasive blaster design was used to first mix the particles with the gas before exiting a conical nozzle. The clumping of particles is unwanted as it changes ballistic properties and decay rate. Clumping was seen with irregular powders, and methods to mitigate this problem are discussed. A summary of trends from testing, designs, and topics for the future end this report., The original document contains color images.

The WindSat instrument is the primary payload for the Coriolis mission which was launched on 6 January 2003. WindSat is a 22-channel conical-scanning radiometer which measures the vertical and horizontal polarizations at nominal center frequencies of 6.8 and 23.8 GHz and six polarizations at nominal center frequencies of 10.7, 18.7, and 37 GHz. The prelaunch WindSat receiver frequency passband measurements are presented and modeled with a functional fit. Radiative transfer simulations are presented which model the differences between the measured brightness temperatures for ocean scenes and the simulated brightness temperatures for the nominal design receiver frequency passbands. Significant differences are shown for the channels with 18.7 and 23.8 GHz nominal center frequencies. These differences are shown to be a function of the precipitable water vapor in the measured scene., The original document contains color images.

This report describes an approach for calculating the bistatic microwave reflectivity of the sea surface for transmit and receive grazing angles less than 10 degrees and any relative geometry through 360 degrees. In the forward scatter region, including specular and glistening zone, the model relies on the work of Beckman and Spizzichino supplemented with later work on shadowing [2] and polarization effects [3]. Outside the forward scatter region, the model is heuristic and based on the similarities between measured monostatic and bistatic sea reflectivity. The motivation behind the model described is the evaluation of the magnitude of jamming reflections into the radar main beam and sidelobes from the sea surface. Such jamming reflections, which sometimes are referred to as hot clutter, can degrade the performance of adaptive jamming cancellation systems. The model also applies to evaluation of the performance of bistatic radar systems. The complete model is incorporated in a single MATLAB function call, used as a basis for a graphic user interface (GUI), which provides a useful tool to analyze a wide range of scenarios. This code is described in two appendixes and will be provided to qualified organizations upon request., The original document contains color images.

Compound-specific stable isotope analysis (CSIA) was applied to a pentaerythritol ester lubricant to determine if predictable fractionation effects could be related to friction stress. A pin-on-disk tribometer was used to expose the lubricant to five doubly-increasing sliding distances (up to 36 km). PCA was used to ordinate multivariate data and test if significant isotopic shifts or FTIR spectral changes could be related to sliding cycles. 13C Isotope ratios only were found to be statistically different (P 0.05) between treatments. PCA gave a primary score (PC1) containing 44% of the 13C-isotopic variability, which correlated exponentially with sliding cycles (r2 = 0.96). A peak, not present in unexposed lubricant, became evident and showed increasing 13C depletion with increasing length of sliding exposure., The original document contains color images. Prepared in collaboration with St. Mary s College of Maryland, St. Mary s City, MD. Sponsored in part by AFOSR.

Toxic airborne contaminants, when inhaled, can cause adverse health effects. The U.S. EPA tabulates three Acute Exposure Guideline Levels (AEGLs) for predicting the onset of these adverse effects from specific length exposures to specific concentrations of toxic chemicals for a general population. Inhalation exposures in the real world, however, vary strongly in space and time and thus do not correspond to the specific durations and exposure levels tabulated by the EPA-a complication that EPA does not resolve. This report gives an accurate, science-based algorithm with fast, easy-to-use software to fill this gap. The software package, called EAGLE, predicts the onset of AEGL 1, 2 and 3 conditions for an arbitrary airborne agent time history supplied by the user. EAGLE can be used with field data, sensor data, wind tunnel measurements, Computational Fluid Dynamics models and rapid-response plume prediction software to convert agent time histories into meaningful actionable health effect predictions. It can also be used to predict the strong effects of realistic concentration fluctuations and to compare plume prediction models in a meaningful way., The original document contains color images.

The existing Navy ships use a separate antenna for each function, resulting in proliferation of a large number of antennas on ships to meet the numerous functional requirements. Recently, wideband phased array antennas are being developed that can perform multiple functions simultaneously to reduce the number of antennas on ships. However, the number of radiating elements needed is prohibitively large, resulting in a complex and costly multifunction phased array antenna. This report discusses novel architectures that can consolidate many functions into a single wideband phased array antenna and at the same time reduce the total number of elements needed, thereby reducing the size, weight, power, and cost compared to a conventional wideband phased array architecture. Besides the number of elements, the number of simultaneous links and element bandwidth requirements are also optimized in an effort to optimize both cost and complexity, The original document contains color images. Prepared in collaboration with the InTop Program Office, Systems Directorate, and Sotera Defense Solutions, Inc. Herndon, VA.

A 5 cubic meter decompression chamber was repurposed as a test chamber to conduct failure abuse experiments on commercial 18650-type lithium-ion batteries. Various modifications were performed to enable remote control and monitoring of chamber functions, along with collection of data from instrumentation during tests including high speed and infrared cameras, a Fourier transform infrared spectrometer, real-time gas analyzers, and compact reconfigurable input and output devices. Single- and multi-cell packages of LiCoO2 and LiFePO4 chemistry 18650 lithium-ion batteries were constructed and data was obtained and analyzed for abuse and failure tests. Observations from recorded camera videos, thermocouples, heat flux gauges, and gas analyses revealed qualitative insights into failure mechanisms and heat propagation from cell to cell. Future directions based on these observations are also proposed., The original document contains color images.

Imaging geostationary satellites from the ground is an important Space Situational Awareness diagnostic tool that will require the use of optical interferometry. We developed a series of imaging and data quality simulations that allow us to investigate issues related to the interferometric imaging of such targets. We discuss the number of baselines and sampling density needed to achieve different resolutions. We investigate the effect of target size relative to the resolving power of a single telescope in the interferometer, and how this in influences the amount of light coupled into a ber and the observed interferometric visibility amplitude. We also investigate a method that will allow one to determine and correct phase variations due to different delay sources in a post-processing way. The results presented here will be important to guide the design of future optical interferometers dedicated to the imaging of geosats., Presented at the Advanced Maui Optical and Space Surveillance Technologies (AMOS) Conference, 9-12 Sep 2014, Maui, HI.

Distributed systems are ubiquitous in computing and engineering, yet they have been somewhat obscured in the philosophical world. A distributed logic is a collection of local modal logics linked together by distributed modal connectives each of which takes formulas in one logic and returns formulas in a different logic. Semantically, each local logic is interpreted over a collection of worlds. Let this collection be called the local collection for this local logic. A local neighborhood (nbd) map takes each world to a set of worlds taken from the local collection and is used to interpret the modal connectives of the local logic. The distributed modal connectives are also interpreted using nbd maps; here, the nbd maps take worlds from a local collection of worlds to nbds of worlds from a different local collection., The original document contains color images.

This report discusses results of two series of STING penetrometer measurements of seafloor sediment strength in areas of Boston Harbor approach. The experimental data is analyzed and used in sediment characterization and sediment strength predictions., The original document contains color images.

Materials for the concentration of nitroenergetic and perchlorate targets from groundwater were developed for monitoring applications. Novel molecular imprinting and structure direction techniques were used to obtain the necessary materials. The potential for concentration of targets from ground and surface waters as well as from soil extracts was demonstrated. The functional characteristics of the materials were evaluated in order to determine the constraints on there use in inline preconcentration of targets ahead of IMS and electrochemical sensing techniques. The systems were subsequently developed at the bench level and function was evaluated using commercially available portable sensors. An initial portable prototype was also developed and evaluated under a field scenario.

Meaningful interoperability between physics-based models requires a common understanding and standardized description of the physical laws governing physical objects, i.e., an ontology of physics and the resulting metadata. For example, currently, the Synthetic Environment Data Representation and Interchange Specification (SEDRIS) standard addresses the description of model data objects, their spatiotemporal coordinates, and many physical attributes. What is not described in SEDRIS are model dynamics, i.e., how a model evolves in time between the discrete states that are represented in transmittals. If model dynamics are not specified with the data, a data recipient will be required to infer how he/she should use the received data, making an inference that will vary depending on the recipient. Of the many factors that may affect model dynamics, such as military doctrine, human behavior, or physics, we focus on representing physical dynamics. This is commonly a necessary aspect of model dynamics. The key concepts in representing physical dynamics are the equations of physics, usually phrased as differential equations, and how they relate to static representations of physical objects, such as those represented in SEDRIS. This paper frames the structure of how to incorporate considerations of dynamics in an ontology of physics and begins to detail the types of physical dynamical relationships that may be modeled.

More than 100 lithium battery casualty tests were conducted to characterize the conditions produced during a range of both unmitigated and mitigated casualties. Both primary and secondary batteries were tested. This report summarizes the data and findings from these tests, including methods of mitigating thermal runaway of these cells under casualty conditions., The original document contains color images. Prepared in collaboration with Hughes Associates, Baltimore, MD.

Graphene is a potential candidate for integrated carbon-based photonics. Its unique combination of mechanical, electrical, and optical properties gives it several advantages in photonic applications. Graphene's physical properties encompass large-area epitaxial monolayer growth, low-dimensional relativistic massless carriers, and universal optical conductivity from the visible to the infrared, to name a few. The object of this report is to provide a basic understanding of graphene and its use in photonic devices, covering the areas of photodetection, optical modulation, optical polarization, plasmonics, and nonlinear optical properties and devices., The original document contains color images.

Cyber warriors need to make quick, effective decisions regarding cyber events: namely, which events should be addressed first (i.e., event triage/prioritization) and what should be done with them (i.e., event response). Events should be triaged based on the potential damage they have to important assets and the overall mission. This enables cyber warriors to better protect critical missions by focusing on high priority events. Existing tools used in current practice do not provide such effective event prioritization. Effective event prioritization should include factors such as the importance of the host, the vulnerabilities of the host, network connectivity, as well as details of the event itself. We developed a framework to prioritize events based on the potential damage that each event can incur to important hosts and missions. The framework gathers, fuses, and integrates relevant information from other security tools and databases for automated event prioritization. We implemented our framework as a flexible, extensible, customizable, and user-friendly tool called ACCEPT., The original document contains color images.

This limited scope, three year SERDP project involves determining the primary biogeochemical factors that control TNT metabolism by natural microbial assemblages in coastal systems. By correlating standard water quality measurements with degradation rates, we can predict turnover times for energetics released into hydrodynamically similar, UXO-impacted ecosystems where access to site samples may be limited. During this first year of sampling in the Florida Keys, USA, we found that mixing experiments between mangrove lagoon water and open ocean Gulf of Mexico water resulted in more rapid rates of bacterial growth and aromatic contaminant mineralization (i.e., TNT, RDX, HMX and phenanthrene) than would have been predicted by interpolation of unmixed end members. This line of evidence supports the hypothesis that coastal mixing zones may lead to more rapid energetic and PAH biodegradation than would be expected using standard measures and techniques. Surveys of energetic and PAH mineralization rates in areas adjacent to DoD sites in the Key West area suggest that contaminants in surface runoff from shoreside areas would be rapidly metabolized (i.e., hours to weeks) in the adjacent seawater and surface sediment. Rapid intrinsic biodegradation rates of such contaminants would potentially mitigate the ecological risk associated with exposure of marine biota to these compounds. In addition, as part of these surveys, the most rapid RDX and HMX mineralization rates associated with any natural assemblage to date were found in the tropical sediment at some stations around Key West. Taken together, this work supports a site conceptual model where PAH and energetics would be rapidly biodegraded by natural microbial assemblages were they to migrate from mangrove-dominated lagoon systems to adjacent coastal waterways in tropical ecosystems., Prepared in collaboration with Marine, Earth, and Atmospheric Sciences, North Carolina State University, Raleigh, NC 27695. The original document contains color images.

Zinc-based batteries offer a safe, inexpensive alternative to fire-prone lithium-based batteries, but zinc-based batteries do not exhibit sufficient rechargeability yet. Breaking through the centuries-old roadblock to zinc-based rechargeable batteries requires rethinking the electrode structure in order to control how zinc converts to zinc oxide during battery discharge and how the oxide is reversed back to metal upon recharging. We address the problems of inefficient zinc utilization and limited rechargeability by redesigning the zinc electrode as a porous, monolithic, three-dimensional (3D) aperiodic architecture. Utilization approaches 90% (728 mA h gZn -1) when the zinc sponge is used as the anode in a primary (single-use) zinc air cell. To probe rechargeability of the 3D Zn sponge, we cycled Zn vs. Zn symmetric cells and Ag Zn full cells under conditions that would otherwise support dendrite growth, and yet the Zn sponges remain dendrite-free after extensive cycling up to 188 mA h gZn-1. By using 3D-wired zinc architectures that innately suppress dendrite formation, all zinc-based chemistries can be reformulated for next-generation rechargeable batteries., The original document contains color images. Published in Energy and Environmental Science, v7 p1117-1124, 2014.

NRL and NAEVA Geophysics conducted a cued classification survey on the remaining 1.75 acres of the 3-acre man-portable subarea selected from within the 330-acre CIA demonstration site. The 2012 NRL survey investigated 1,005 anomalies in the northern 1.25 acres of the man- portable area. Cued data collection was conducted for the remaining 1,429 anomalies previously identified. This survey used the NRL TEMTADS MP 2x2 Cart (MP System) operating in litter-carry mode. Characterization of the system responses to the Targets of Interest (TOIs) was based on previously acquired TEMTADS reference data. These data were collected in accordance with the overall study objectives and demonstration plan. Unlike the 2012 demonstration, classification analysis of the interrogated anomalies was conducted as well. This document describes the results of the demonstration., The original document contains color images.

In this paper an analysis of remote atmospheric magnetometry concepts, based on using molecular oxygen as the paramagnetic species, is presented. The objective is to use these concepts as possible mechanisms for the detection of underwater and underground objects. The formulation is based on the coupled Maxwell-density matrix system of equations. We use these coupled equations to describe the magnetization of a paramagnetic species in the presence of an intense modulated laser pulse and ambient magnetic field. The O2 magnetic dipole transition line that is considered is the b1 Sigma g+ - X3 Sigma g- transition band of oxygen near 762 nm. A high-intensity, repetition rate, polarized titanium-doped sapphire laser is considered for the pump. The nonlinear formulation is used to investigate magnetic anomaly detection mechanisms using i) wakefield polarization rotation and, ii) polarization changes in resonance fluorescence emission (Hanle effect). The major challenges for these related approaches is the collisional dephasing of the atmospheric oxygen transitions and the strength of the magnetic dipole moment., The original document contains color images.

In this report, we examine the formalism of coupled mode theory from several viewpoints, using the fiber optic directional coupler as a model problem to unify the discussion. With this model, we present the basic maps and tools used in describing coupled systems, emphasizing the connections between the approaches by using a consistent notation across phasor, matix algebra, and geometrical descriptions, The original document contains color images.

The TEMTADS 5x5 Array was demonstrated at two sites, the former Mare Island Naval Shipyard, CA, in 2011, and the former Spencer Artillery Range, TN (fSpAR) in 2012. The MP System was demonstrated at the former Camp Beale, VA, in 2011, and the Central Impact Area of the Massachusetts Military Reservation and fSpAR in 2012. For each site and system, 180 or more target locations were investigated per day with limited rework required. The limited data set of dynamic data collected with the MP System at fSpAR was used to ultimately detect all seed items within the area. Approximately 70 percent of the detected anomalies could be classified from the dynamic data alone. Using a combination of results from dynamic and cued data, 100% of the identified UXO were correctly classified, and the number of necessary digs could be reduced by at least 75 percent., The original document contains color images.

This document presents the concept of operations for the tungsten-particle dispenser spacecraft and supporting systems used in the formation of an artificial ring of dust for active orbital debris removal. Previous papers explained the ring of dust that increases drag on small orbital debris causing it to decrease altitude and enter the Earth s atmosphere. Because this technique is novel, legal and international issues are recognized to allow the engineering community to become aware of these challenges early in the mission development. A short review of earlier work motivates the mission goals and the size and quantity of tungsten spheres to be dispensed along an orbiting ring 1,100 km circular altitude at 90 deg inclination. Discussion of spacecraft subsystems is capped with a review of spacecraft modes and fault detection. Large capacity launch vehicles are indicated for this mission and launch sites supporting polar orbits are noted. Mission and ground operations support is highlighted along with the suggestion that ground stations near the poles are better suited for this orbit inclination. A chronological discussion of a normal mission is presented. Suggested secondary engineering mission goals are given to detect the structure of the ring and its effectiveness at decaying the orbit debris. This document concludes with a summary listing of guidelines for future requirements vetting., The original document contains color images.

Day recently obtained phase-only element weights for a large transmit array of arbitrary geometry by optimizing complex weights using an objective function that penalized amplitude variation. He used gradient descent modified with a classic SVD technique to create point and sector nulls as desired. Here Day's approach is extended to allow for main-beam broadening as might be needed to illuminate multiple receive beams. This is done by adding a second objective term, one penalizing variation in array-factor amplitude across a grid of beamspace points covering the desired broad main-beam. The tension between the two objective terms turns out to be challenging to manage, and at this preliminary stage of algorithm development, parameter scheduling across a sequence of stages of the optimization is required to obtain good solutions., The original document contains color images.