Naval Air Warfare Center Research Articles

Investigation of the Roles of Functional Solvents in Performance Stability of High Voltage Lithium Batteries

Li-ion batteries (LIBs) have become prevalent for portable and large-scale applications, such as personal electronic devices, unmanned aircraft systems, electric vehicles, and power grids.1 However, LIBs are approaching an asymptotic limit in specific energy (~250 Wh kg-1 at cell level); therefore, they are insufficient to meet future applications that require higher battery specific energies.2 Ni-rich cathodes, such as LiNi0.8Co0.1Mn0.1O2 (NMC811), have the potential to provide much higher specific energies for next-generation LIBs (e.g., >350 Wh kg-1) and, therefore, are considered the most promising low-cost cathode materials.3 Nevertheless, Ni-rich cathode based LIBs with conventional carbonate solvent based electrolytes face severe technical challenges, especially when cycled at high upper cutoff voltages, due to electrolyte decomposition, parasitic oxidation reactions at the electrolyte/cathode interface, irreversible phase changes in the cathodes, and dissolution of transition metals into electrolytes.4 Therefore, R&D efforts are needed to tackle the above technical challenges of Ni-rich cathode based LIBs before they become commercially viable.In our previous study,5 a ternary of fluorinated solvents was used to formulate a high voltage stable electrolyte (HVE) which was used in Ni-rich cathode based, high-voltage lithium batteries. These HVE-based batteries demonstrated a significant improvement in cycle stability when operated at a charge cutoff voltage of 4.5 V (vs Li/Li+). In this study, we investigated the roles of single-solvents and co-solvents in the cycle stability of the high-voltage lithium batteries. Several families of organic solvents, such as fluorinated carbonates and organosilicon based solvents were investigated. Our preliminary data showed that some unique combinations of the functional solvents could lead to exceptionally stable cycle performance in the high-voltage lithium batteries. We will discuss possible fundamental mechanisms responsible for the observed performance stability of the high-voltage lithium batteries using ex-situ XPS, density functional theory calculations, and other characterization techniques. References (1) Li, J.; Fleetwood, J.; Hawley, W. B.; Kays, W. From materials to cell: state-of-the-art and prospective technologies for lithium-ion battery electrode processing. Chemical Reviews 2021, 122 (1), 903-956.(2) Khan, F. N. U.; Rasul, M. G.; Sayem, A.; Mandal, N. K. Design and optimization of lithium-ion battery as an efficient energy storage device for electric vehicles: A comprehensive review. Journal of Energy Storage 2023, 71, 108033.(3) Xue, W.; Huang, M.; Li, Y.; Zhu, Y. G.; Gao, R.; Xiao, X.; Zhang, W.; Li, S.; Xu, G.; Yu, Y. Ultra-high-voltage Ni-rich layered cathodes in practical Li metal batteries enabled by a sulfonamide-based electrolyte. Nature Energy 2021, 6 (5), 495-505.(4) Yang, J.; Liang, X.; Ryu, H.-H.; Yoon, C. S.; Sun, Y.-K. Ni-Rich Layered Cathodes for Lithium-Ion Batteries: From Challenges to the Future. Energy Storage Materials 2023, 102969.(5) Poches, C.; Razzaq, A. A.; Studer, H.; Ogilvie, R.; Lama, B.; Paudel, T. R.; Li, X.; Pupek, K.; Xing, W. Fluorinated High-Voltage Electrolytes To Stabilize Nickel-Rich Lithium Batteries. ACS Applied Materials & Interfaces 2023, 15 (37), 43648-43655. Acknowledgement This work was supported by the following funding sources. The Larry and Linda Pearson Endowed Chair at the Department of Mechanical Engineering, South Dakoda School of Mines and Technology. The Naval Air Warfare Center Weapons Division, China Lake, CA under Contract No N6893622C0017. Any opinions, findings and conclusions or recommendations expressed in this material are those of the author(s) and do not necessarily reflect the views of the Naval Air Warfare Center Weapons Division, China Lake, CA. TP acknowledges the support from the SDBOR Governor Research Center for the Electrochemical Energy Storage and NASA EPSCOR-80NSSC23M0072.

Inspiring Future Rocket Chemists: A Hands-On Instructional Event Highlighting the Role Chemistry plays in the Fundamentals of Rocketry

Motivational hands-on workshops for grade-school level future scientists are needed to inspire young and receptive minds. Described here is an educational event, titled “Inspiring Future Rocket Chemists”, with hands-on laboratory exercises demonstrating the fundamentals of rocket flight and live chemistry demonstrations illustrating the fundamentals of rocket propulsion. This event was developed for seventh and eighth grade students by the local Mojave Desert Section of the American Chemical Society and the China Lake Museum Foundation (CLMF). The CLMF is dedicated to educating the public and preserving the history of the Naval Air Warfare Center Weapons Division’s contributions to our nation’s warfighters. The workshop was developed and led by experts currently working in or retired from the rocket science field. Four hands-on exercises and four demonstrations were performed with the students. The laboratory exercises and demonstrations covered topics including model rocket components and assembly, rocket stability, propulsion, safety, chemical reactions, gas generation, and catalysis in propellants. Two distinguishing characteristics of this event was the inclusion of fundamental principles of rocket science and emphasis on the interdisciplinary nature of the field. The event’s pedagogical goals were to motivate and inspire the participants in exploring the field of rocketry while teaching them the fundamental properties and important safety precautions for practicing rocketry. This event serves as the framework for future collaborative efforts between institutions for specialized workshops in topic areas not traditionally covered in student’s coursework. The effectiveness of the event was measured through student assessments and feedback at the conclusion of the event.

Evaluating the Challenges and Potential Complications of Breastfeeding in Naval Aviation.

Active duty flight crew plays a critical role in military operations. The occupational demands of the flying environment require a certain level of medical suitability. Additionally, such an environment could be more hazardous for certain populations. While the Centers for Disease Control and Prevention, the American Academy of Pediatrics, and the World Health Organization strongly support exclusive breastfeeding for the health benefit of both the mother and the child in the first 6 months of life, the aeromedical implications of lactating are not widely discussed. Breastfeeding is inherently challenging for many women, in part because of the frequent emptying required to maintain breastmilk supply and avoid complications such as engorgement, clogged ducts, and mastitis. This pilot study evaluated the experiences of individuals concurrently breastfeeding while on active duty Naval flying status to (1) assess whether these individuals experience frequent challenges or complications associated with lactating and (2) establish the need for future expanded studies. This survey-based, retrospective, descriptive study evaluated the experiences of 17 lactating individuals on active duty Naval flying status. Women were recruited using word of mouth and social media platforms. Responses were tabulated and summarized from the survey, which included yes/no questions and free-response sections regarding flying position, breastfeeding history, and breastfeeding challenges. This trial was approved by the Naval Air Warfare Center Aircraft Division (NAWCAD) Institutional Review Board (Protocol Number NAWCAD.2021.0004-IR-EP7). Of the 27 women who received study materials after expression of interest, 17 individuals completed the informed consent and survey protocols. Although limited by sample size and the demographics of respondents, the results highlight that the active duty flying environment did impact the breastfeeding experiences of the participants, with 88% of respondents reporting some difficulty or complication associated with breastfeeding and the operational flying environment. Difficulty in maintaining breastmilk supply, engorgement, and the need for supplementation were some of the concerns discussed. This study hypothesizes that occupational demands associated with aviation result in a decreased ability to maintain exclusive breastfeeding, an increased risk for engorgement and clogged ducts, and a higher likelihood of early weaning among Naval aviators. It included only the perspectives of Naval officers, thereby lacking the input of enlisted aircrew on flight status, who comprise a large population of active duty flyers. The responses, although limited by a lack of controls and survey limitations, indicate that a future study to expand understanding of the aeromedical implications on lactating individuals would be valuable for improving workplace support and the ultimate success of lactating women in meeting their breastfeeding goals.

High Voltage Electrolytes to Stabilize Ni-Rich Lithium Battery Performance

State-of-the-art (SOA) lithium-ion (Li-ion) batteries are approaching their specific energy density limit (~250 Wh kg−1).1 Layered structured, nickel-rich (Ni-rich or high Ni content) lithium transition metal oxides, e.g., LiNi0.8Mn0.1Co0.1O2 (NMC811), have attracted great interests2 owning to their practically deliverable high specific capacity >200 mAh/g. Coupled with high average discharge voltages (~4V vs. Li/Li+), Ni-rich cathode-based lithium batteries possess a great potential to achieve much higher specific energies, e.g., >350 Wh/kg at cell level targeted for electric drive vehicles,3 than SOA Li-ion batteries. In addition, Ni-rich oxides are economically viable as low-cost battery cathode materials due to their low cobalt content. However, Ni-rich cathode-based Li-ion batteries exhibit a quick capacity degradation upon cycling particularly at high charge cutoff voltages (e.g., 4.5V vs. Li/Li+) and at elevated temperatures. Possible degradation mechanisms of Ni-rich based Li cells include structural changes of the material (large c-axis shrinkage at high potentials)4 and parasitic reactions that arise from the interactions between the electrolytes and highly reactive delithiated cathode surface (due to high oxidation state Ni4+ ions).5,6 Therefore, R&D efforts are needed to tackle technical challenges facing the Ni-rick based Li batteries before they become commercially viable.We will present our efforts of developing high voltage electrolytes to afford stable electrochemical performance of Ni-rich cathode-based Li cells. Figure 1 shows the electrochemical performance of NMC-811 cathode, paired Li metal anode, in conventional Li-ion battery electrolyte (Baseline electrolyte) and the high voltage electrolyte developed in this study, evaluated at C/4 rate during the formation and 1 C rate during cycling, between 2.5V and 4.5V, at room temperature. The cell with the high voltage electrolyte maintained ~80% capacity retention after 400 cycles. In contract, the cell with the baseline electrolyte experieced a large capacity fade with only ~25% capacity retention after 400 cycles. The superior cycle stability of the high votage electrolyte, Ni-rich based cell is attributed to the inharently high-voltage stable, multi-functional. Electrolyte chemical structures and their correlation with the electrochemical stability will be discussed. References Chen, W.; Lei, T.; Qian, T.; Lv, W.; He, W.; Wu, C.; Liu, X.; Liu, J.; Chen, B.; Yan, C.; Xiong, J., Advanced Energy Materials 2018, 8 (12).Jiang, M.; Danilov, D. L.; Eichel, R.-A.; Notten, P. H. L., Advanced Energy Materials 2021, 11 (48), 2103005.Gomez‐Martin, A.; Reissig, F.; Frankenstein, L.; Heidbüchel, M.; Winter, M.; Placke, T.; Schmuch, R., Advanced Energy Materials 2022, 12 (8).Cho, D.-H.; Jo, C.-H.; Cho, W.; Kim, Y.-J.; Yashiro, H.; Sun, Y.-K.; Myung, S.-T., Journal of The Electrochemical Society 2014, 161 (6), A920-A926.Chen, C. H.; Liu, J.; Amine, K., Journal of Power Sources 2001, 96 (2), 321-328.Li, J.; Downie, L. E.; Ma, L.; Qiu, W.; Dahn, J. R., Journal of The Electrochemical Society 2015, 162 (7), A1401-A1408. Acknowledgement This material is based upon work supported by the Naval Air Warfare Center Weapons Division, China Lake, CA under Contract No N6893622C0017. Any opinions, findings and conclusions or recommendations expressed in this material are those of the author(s) and do not necessarily reflect the views of the Naval Air Warfare Center Weapons Division, China Lake, CA. Figure 1

Swarms of Pirates: Red Team Exercises Using Autonomous High-Speed Maneuvering Surface Vessels

We present a final overview of the efforts by the Naval Air Warfare Center Weapons Division (NAWCWD) and the Jet Propulsion Laboratory to automate the operation of the largest fleet of autonomous maritime vehicles. The vehicles are intended for large-scale demonstrations and tests of US Navy systems or tactics. This review covers a preexisting distributed architecture for human-in-the-loop control of several autonomous high-speed boats with a main focus on the planning, formation assignment, and formation switching pipeline. Algorithm capabilities are described and validated in simulation and field tests using real-world vehicles. Theoretical lower bounds on the time required to change formations are also derived and used to bound our experimental performance. We are able to present data from the 2019 “final exam” that pitted this architecture in a head-to-head competition, which was won after a perfect run with no hazardous maneuvers recorded under autonomous control. The effort concluded successfully on December 31, 2020, with the delivery of code and documentation after successful integration and testing exercises in 2019 and 2020. We conclude the paper with discussions of limitations, extensions, and suggestions for future work.

Record-breaking molecular magnet

By coupling a pair of lanthanide ions within the same compound, researchers have created what they believe are the most magnetic molecules ever made ( Science 2022, DOI: 10.1126/science.abl5470 ). “By all the traditional metrics of single-molecule magnets, they’re the best,” Nicholas Chilton says of the new molecules. Chilton, who’s based at the University of Manchester, collaborated on the work with Jeffrey Long at the University of California, Berkeley, and Benjamin Harvey at the US Naval Air Warfare Center Weapons Division. Although the molecules’ magnetism reveals itself only at low temperatures, Chilton hopes that these dilanthanide complexes might pave the way for new types of powerful yet lightweight permanent magnets. “This really is a very, very important piece of work,” says Roberta Sessoli of the University of Florence, a pioneer of single-molecule magnets who was not involved in the project. “This is something that is going to remain as a

Processing, Adhesion and Corrosion-inhibiting Properties of Poly[2-methoxy-5-(2’-ethylhexyloxy)-1,4-phenylene vinylene], (MEH-PPV) on Aerospace Aluminum Alloys

Researchers at the Naval Air Warfare Center Weapons Division (NAWCWD) and Wright-Patterson Air Force Base (WPAFB) investigated poly[2-methoxy-5-(2’-ethylhexyloxy)-1,4-phenylene vinylene], (MEH-PPV) for its potential corrosion-inhibition properties on aerospace aluminum alloy AA2024-T3. Solution processing of the polymer, as well as adhesion testing and accelerated weathering tests were performed on MEH-PPV full military aerospace coatings. Wet and dry tape adhesion testing, as well as pencil hardness, impact flexibility and pneumatic adhesion tensile test instrument (PATTI) testing were used to demonstrate the adhesion performance of MEH-PPV on aluminum substrates. The results showed that MEH-PPV had acceptable adhesion characteristics when compared to hexavalent chromium (Cr(VI)) based coatings in all of these tests. Accelerated weathering analysis was performed on MEH-PPV coatings to determine their corrosion protection and weathering resistance capabilities. These tests included neutral salt spray (NSS) exposure and xenon-arc lamp testing. The results showed that while MEH-PPV does not exhibit significant color change after 500 hours of xenon arc lamp exposure, the polymer has poor corrosion protection performance under aggressive salt environments.

Bio-Based Cycloalkanes: The Missing Link to High-Performance Sustainable Jet Fuels.

Invited for this month's cover is the group of Ben Harvey at the Naval Air Warfare Center, Weapons Division, China Lake. The image shows several examples of bio-based cycloalkanes that have been developed as next-generation sustainable jet fuels. The Review itself is available at 10.1002/cssc.202001641.

Hydraulic Tomography: 3D Hydraulic Conductivity, Fracture Network, and Connectivity in Mudstone.

We present the first demonstration of hydraulic tomography (HT) to estimate the three-dimensional (3D) hydraulic conductivity (K) distribution of a fractured aquifer at high-resolution field scale (HRFS), including the fracture network and connectivity through it. We invert drawdown data collected from packer-isolated borehole intervals during 42 pumping tests in a wellfield at the former Naval Air Warfare Center, West Trenton, New Jersey, in the Newark Basin. Five additional tests were reserved for a quality check of HT results. We used an equivalent porous medium forward model and geostatistical inversion to estimate 3D K at high resolution (K blocks <1 m3 ), using no strict assumptions about K variability or fracture statistics. The resulting 3D K estimate ranges from approximately 0.1 (highest-K fractures) to approximately 10-13 m/s (unfractured mudstone). Important estimated features include: (1) a highly fractured zone (HFZ) consisting of a sequence of high-K bedding-plane fractures; (2) a low-K zone that disrupts the HFZ; (3) several secondary fractures of limited extent; and (4) regions of very low-K rock matrix. The 3D K estimate explains complex drawdown behavior observed in the field. Drawdown tracing and particle tracking simulations reveal a 3D fracture network within the estimated K distribution, and connectivity routes through the network. Model fit is best in the shallower part of the wellfield, with high density of observations and tests. The capabilities of HT demonstrated for 3D fractured aquifer characterization at HRFS may support improved in situ remediation for contaminant source zones, and applications in mining, repository assessment, or geotechnical engineering.

Digital Logistics Capability: Factors Impacting Technology Acceptance

The Naval Air Warfare Center Aircraft Division Logistics Competency is implementing new technology that will transform the way that logistics analysis is performed. Implementing technology can be a challenge for organizations and especially when the technology disrupts the existing logistics processes. Some of the workforce may view the use of digital devices as frustrating and are likely to be reluctant to accept the new technology even with its enhanced benefits that improve logistics. This research uses a systematic review and thematic synthesis to identify the factors impacting a user’s perceptions of the technology and how their perceptions influence acceptance through the theoretical lens of the technology acceptance model. A user’s acceptance is influenced by their perceptions of the complexity and usability of the technology, leadership’s demonstrated support of the technology, and self-perceptions of self-efficacy and trust. Managers should introduce the technology with a positive attitude, choose early adopters to influence peers, and provide tailored training according to the user’s comfort and perceptions to increase trust and increase acceptance.

Synthesis and Characterization of bis(Tetrahydrofurfuryl) Ether.

Invited for this month's cover are researchers from the Naval Air Warfare Center Weapons Division (USA). The cover picture shows the elusive symmetric molecule bis(tetrahydrofurfuryl) ether (BTHFE) in the making. For more details, read the full text of the Communication at 10.1002/open.201600013.

High-resolution delineation of chlorinated volatile organic compounds in a dipping, fractured mudstone: Depth- and strata-dependent spatial variability from rock-core sampling

Synthesis of rock-core sampling and chlorinated volatile organic compound (CVOC) analysis at five coreholes, with hydraulic and water-quality monitoring and a detailed hydrogeologic framework, was used to characterize the fine-scale distribution of CVOCs in dipping, fractured mudstones of the Lockatong Formation of Triassic age, of the Newark Basin in West Trenton, New Jersey. From these results, a refined conceptual model for more than 55years of migration of CVOCs and depth- and strata-dependent rock-matrix contamination was developed. Industrial use of trichloroethene (TCE) at the former Naval Air Warfare Center (NAWC) from 1953 to 1995 resulted in dense non-aqueous phase liquid (DNAPL) TCE and dissolved TCE and related breakdown products, including other CVOCs, in underlying mudstones. Shallow highly weathered and fractured strata overlie unweathered, gently dipping, fractured strata that become progressively less fractured with depth. The unweathered lithology includes black highly fractured (fissile) carbon-rich strata, gray mildly fractured thinly layered (laminated) strata, and light-gray weakly fractured massive strata. CVOC concentrations in water samples pumped from the shallow weathered and highly fractured strata remain elevated near residual DNAPL TCE, but dilution by uncontaminated recharge, and other natural and engineered attenuation processes, have substantially reduced concentrations along flow paths removed from sources and residual DNAPL. CVOCs also were detected in most rock-core samples in source areas in shallow wells. In many locations, lower aqueous concentrations, compared to rock core concentrations, suggest that CVOCs are presently back-diffusing from the rock matrix. Below the weathered and highly fractured strata, and to depths of at least 50meters (m), groundwater flow and contaminant transport is primarily in bedding-plane-oriented fractures in thin fissile high-carbon strata, and in fractured, laminated strata of the gently dipping mudstones. Despite more than 18years of pump and treat (P&T) remediation, and natural attenuation processes, CVOC concentrations in aqueous samples pumped from these deeper strata remain elevated in isolated intervals. DNAPL was detected in one borehole during coring at a depth of 27m. In contrast to core samples from the weathered zone, concentrations in core samples from deeper unweathered and unfractured strata are typically below detection. However, high CVOC concentrations were found in isolated samples from fissile black carbon-rich strata and fractured gray laminated strata. Aqueous-phase concentrations were correspondingly high in samples pumped from these strata via short-interval wells or packer-isolated zones in long boreholes. A refined conceptual site model considers that prior to P&T remediation groundwater flow was primarily subhorizontal in the higher-permeability near surface strata, and the bulk of contaminant mass was shallow. CVOCs diffused into these fractured and weathered mudstones. DNAPL and high concentrations of CVOCs migrated slowly down in deeper unweathered strata, primarily along isolated dipping bedding-plane fractures. After P&T began in 1995, using wells open to both shallow and deep strata, downward transport of dissolved CVOCs accelerated. Diffusion of TCE and other CVOCs from deeper fractures penetrated only a few centimeters into the unweathered rock matrix, likely due to sorption of CVOCs on rock organic carbon. Remediation in the deep, unweathered strata may benefit from the relatively limited migration of CVOCs into the rock matrix. Synthesis of rock core sampling from closely spaced boreholes with geophysical logging and hydraulic testing improves understanding of the controls on CVOC delineation and informs remediation design and monitoring.

Integration of stable carbon isotope, microbial community, dissolved hydrogen gas, and 2HH2O tracer data to assess bioaugmentation for chlorinated ethene degradation in fractured rocks

An in situ bioaugmentation (BA) experiment was conducted to understand processes controlling microbial dechlorination of trichloroethene (TCE) in groundwater at the Naval Air Warfare Center (NAWC), West Trenton, NJ. In the BA experiment, an electron donor (emulsified vegetable oil and sodium lactate) and a chloro-respiring microbial consortium were injected into a well in fractured mudstone of Triassic age. Water enriched in ²H was also injected as a tracer of the BA solution, to monitor advective transport processes. The changes in concentration and the δ¹³C of TCE, cis-dichloroethene (cis-DCE), and vinyl chloride (VC); the δ²H of water; changes in the abundance of the microbial communities; and the concentration of dissolved H₂ gas compared to pre- test conditions, provided multiple lines of evidence that enhanced biodegradation occurred in the injection well and in two downgradient wells. For those wells where the biodegradation was stimulated intensively, the sum of the molar chlorinated ethene (CE) concentrations in post-BA water was higher than that of the sum of the pre-BA background molar CE concentrations. The concentration ratios of TCE/(cis-DCE+VC) indicated that the increase in molar CE concentration may result from additional TCE mobilized from the rock matrix in response to the oil injection or due to desorption/diffusion. The stable carbon isotope mass-balance calculations show that the weighted average ¹³C isotope of the CEs was enriched for around a year compared to the background value in a two year monitoring period, an effective indication that dechlorination of VC was occurring. Insights gained from this study can be applied to efforts to use BA in other fractured rock systems. The study demonstrates that a BA approach can substantially enhance in situ bioremediation not only in fractures connected to the injection well, but also in the rock matrix around the well due to processes such as diffusion and desorption. Because the effect of the BA was intensive only in wells where an amendment was distributed during injection, it is necessary to adequately distribute the amendments throughout the fractured rock to achieve substantial bioremediation. The slowdown in BA effect after a year is due to some extend to the decrease abundant of appropriate microbes, but more likely the decreased concentration of electron donor.

Enhanced dichloroethene biodegradation in fractured rock under biostimulated and bioaugmented conditions

AbstractSignificant microbial reductive dechlorination of [1,2 14C] cis‐dichloroethene (DCE) was observed in anoxic microcosms prepared with unamended, fractured rock aquifer materials, which were colonized in situ at multiple depths in two boreholes at the Naval Air Warfare Center (NAWC) in West Trenton, New Jersey. The lack of significant reductive dechlorination in corresponding water‐only treatments indicated that chlororespiration activity in unamended, fractured rock treatments was primarily associated with colonized core material. In these unamended fractured rock microcosms, activity was highest in the shallow zones and generally decreased with increasing depth. Electron‐donor amendment (biostimulation) enhanced chlororespiration in some but not all treatments. In contrast, combining electron‐donor amendment with KB1 amendment (bioaugmentation) enhanced chlororespiration in all treatments and substantially reduced the variability in chlororespiration activity both within and between treatments. These results indicate (1) that a potential for chlororespiration‐based bioremediation exists at NAWC Trenton but is limited under nonengineered conditions, (2) that the limitation on chlororespiration activity is not entirely due to electron‐donor availability, and (3) that a bioaugmentation approach can substantially enhance in situ bioremediation if the requisite amendments can be adequately distributed throughout the fractured rock matrix. © 2012 Wiley Periodicals, Inc.*

Estimated trichloroethene transformation rates due to naturally occurring biodegradation in a fractured rock aquifer

AbstractRates of trichloroethene (TCE) mass transformed by naturally occurring biodegradation processes in a fractured rock aquifer underlying a former Naval Air Warfare Center (NAWC) site in West Trenton, New Jersey, were estimated. The methodology included (1) dividing the site into eight elements of equal size and vertically integrating observed concentrations of two daughter products of TCE biodegradation—cis‐dichloroethene (cis‐DCE) and chloride—using water chemistry data from a network of 88 observation wells; (2) summing the molar mass of cis‐DCE, the first biodegradation product of TCE, to provide a probable underestimate of reductive biodegradation of TCE, (3) summing the molar mass of chloride, the final product of chlorinated ethene degradation, to provide a probable overestimate of overall biodegradation. Finally, lower and higher estimates of aquifer porosities and groundwater residence times were used to estimate a range of overall transformation rates. The highest TCE transformation rates estimated using this procedure for the combined overburden and bedrock aquifers was 945 kg/yr, and the lowest was 37 kg/yr. However, hydrologic considerations suggest that approximately 100 to 500 kg/yr is the probable range for overall TCE transformation rates in this system. Estimated rates of TCE transformation were much higher in shallow overburden sediments (approximately 100 to 500 kg/yr) than in the deeper bedrock aquifer (approximately 20 to 0.15 kg/yr), which reflects the higher porosity and higher contaminant mass present in the overburden. By way of comparison, pump‐and‐treat operations at the NAWC site are estimated to have removed between 1,073 and 1,565 kg/yr of TCE between 1996 and 2009. © 2012 Wiley Periodicals, Inc.*

Integrated characterization of the geologic framework of a contaminated site in West Trenton, New Jersey

Abstract Fractured sedimentary bedrock and groundwater at the former Naval Air Warfare Center in West Trenton, New Jersey (United States of America) are contaminated with chlorinated solvents. Predicting contaminant migration or removing the contaminants requires an understanding of the geology. Consequently, the geologic framework near the site was characterized with four different methods having different spatial scales: geologic field mapping, analyses of bedrock drill core, analyses of soil and regolith, and S -wave refraction surveys. A fault zone is in the southeast corner of the site and separates two distinct sedimentary formations; the fault zone dips (steeply) southeasterly, strikes northeasterly, and extends at least 550 m along its strike direction. Drill core from the fault zone is extensively brecciated and includes evidence of tectonic contraction. Approximately 300 m east of this fault zone is another fault zone, which offsets the contact between the two sedimentary formations. The S -wave refraction surveys identified both fault zones beneath soil and regolith and thereby provided constraints on their lateral extent and location.

Evaluation of procedural changes for minimizing noise impact near military airfields

Over time, communities surrounding military airfields tend to grow, while the noise generated by subsequent generations of military aircraft tends to increase. This creates an accelerating problem of human exposure to noise. One technique to alleviate this disparity is to modify attributes of flight trajectories in a way that reduces the sound exposure of the population. This involves the changing of flight ground tracks, profiles, and power settings within linear and non-linear boundaries which can include exceptions (such as no-fly-zones.) To demonstrate the effectiveness of these changes, DNL levels are calculated for real world population distributions and existing Navy departure procedures. These values are generated computationally using the widely accepted NoiseMap model. It is shown that significant reductions of exposure averaged over the population can be achieved in this way. Possible methods for automating this procedure are discussed. Properties of the objective function spaces are explored (e.g., convexity) and the appropriateness of different optimization methods is discussed. [Work supported by Naval Air Warfare Center.]

Advanced Image Processing for Defense and Security Applications

1Department of Electrical and Computer Engineering, Indiana University-Purdue University Indianapolis, 723W. Michigan Street, SL 160, Indainapolis, IN 46259, USA 2Department of Electrical Engineering, US Naval Academy, 105 Maryland Avenue, MS 14B, Annapolis, MD 21402, USA 3 Image and Signal Processing Branch, Research Department, Naval Air Warfare Center, 1900 N Knox Road, M/S 6302, China Lake, CA 93555, USA 4School of Computer Science, Tokyo University of Technology, 1404-1 Katakura, Hachioji, Tokyo 192-0982, Japan

Modeling of Underwater Bomb Trajectory for Mine Clearance

The falling of a Joint Direct Attack Munition (JDAM) through a water column was modeled using a six degrees of freedom model (called STRIKE35), which contains three components: hydrodynamics, semi-empirical determination of the drag/ lift/torque coefficients (depending on the Reynolds number and the angle of attack), and water surface characteristics.To validate and verify this model, three underwater bomb trajectory tests were conducted in the Naval Air Warfare Center, Weapons Division (NAWC/WD) in the middle of Indian Wells Valley, California. During the test, several JDAMs were dropped from an airplane into two frustum ponds with the same bottom diameter of approximately 30.5 m, different surface diameters (61 m, 79 m), and different depths (7.6 m, 12.1 m). High-speed digital cameras with light/pressure sensors, and a global positioning system were used to record the location and orientation of JDAMs. Model—data inter comparison shows the capability of STRIKE35, which may lead to a new approach (breaching technology) of sea mine clearance in very shallow water (water depth less than 12.2 m, i.e. 40 ft).

Carrier Air Wing Mishap Reduction Using a Human Factors Classification System and Risk Management

In 1998, the Navy's center of excellence for advanced air wing combat operations, namely the Naval Strike and Air Warfare Center (NSAWC), had a spike in Class A flight mishaps. The spike triggered an intense review of prior mishaps and current mishap-reduction practices using the Human Factors Analysis and Classification System (HFACS). The review resulted in NSAWC instituting a comprehensive multifactorial mishap reduction plan applying Operational Risk Management (ORM) precepts. This is a nonrandomized investigational study with use of a historical comparison population. The Class A mishap rate per flight hour covering 10 yr prior to the mishap reduction efforts was estimated and compared to the Class A mishap rate per flight hour for the 10 yr after implementation using Poisson regression. Combined Fleet and NSAWC data shows a 27% reduction in mishap rate, but the 21% reduction in the Fleet alone was not statistically significant. The mishap reduction at NSAWC was statistically significant with an 84% reduction. Fallon carrier air wing mishap rates post-ORM mishap reduction efforts are approaching those seen in the Fleet, but are still elevated overall (3.7 vs. 2.4). The incidence rate ratio was 80% lower at Fallon than the rest of the Fleet, indicating a significantly greater reduction in NSAWC air wing mishaps and suggests focused aviation mishap reduction efforts in similar circumstances could result in similar reductions.