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Measuring and predicting optical turbulence is difficult and requires specialized equipment. NPS Meteorology Department has a developed model, Navy Atmospheric Vertical Surface Layer Model (NAVSLaM), to predict optical turbulence in the surface layer (up to ~100 m above the ocean or land) based upon atmospheric measurements using simple, robust sensors. On the other hand, the Physics Department has developed machine learning models of optical turbulence using atmospheric measurements. This research measures optical turbulence over many months using sonic anemometers that served as the baseline to compare prediction from the models. Atmospheric parameters such as air temperature, wind speed, humidity at two different heights as well as solar flux and ground temperature were simultaneously collected. Those data were used as input for NAVSLaM and machine learning models to predict optical turbulence. We then compared the performance of these prediction models to each other by calculating the root-mean-square error with respect to the baseline data from the sonic anemometers. The results from this research will help determine which model is more reliable to the given environment., Office of Naval Research (Arlington, VA 22217), Lieutenant Commander, Indonesian Navy, Approved for public release. Distribution is unlimited.

This thesis considers the case of a drone defending a high-value target from a number of inbound attacking drones. The defending drone is equipped with short-range weapons and must destroy each of the attacking drones in the most efficient manner. This problem sits at the intersection of several open problems in applied mathematics, such as optimal motion planning in the presence of attrition, as well as solving a “traveling salesman problem” (TSP) with moving targets. The purpose of our research was to analyze this problem by decomposing it into the component problems and then presenting proof-of-concept solutions of each component. The primary results of this thesis include a modeling framework where optimization can be performed without requiring constraints; comparing the strengths of using different types of cost functions for optimization (e.g., minimizing the chance of high-value unit destruction versus a metric based on the path of the defender relative to attackers); and solving moving-target TSP in certain limits by mapping it onto standard TSP or using machine learning., Cruiser/ONR, Major, United States Marine Corps, Approved for public release. Distribution is unlimited.

The Lead-cooled Fast Reactor (LFR), a prominent category of Generation IV advanced reactors, involves design challenges for reactor plant in-service inspection (ISI) due to high operating temperatures, coolant opacities that prevent visual inspection, and the tendency for coolant corrosive attack. These challenges limit the feasibility and effectiveness of conventional ISI technologies. To overcome these challenges, acoustic methods that can operate under high temperature conditions are being actively considered in the U.S. as well as internationally. This research investigates the application of ultrasonic transducers, either piezoelectric or electro-magnetic, for LFR inspections. COMSOL Multiphysics software is used to model the effectiveness of thickness measurements, defect detections, and acoustic reflectance, for the reactor vessel and components within or in contact with the coolant. Acoustic absorption due to wave propagation through molten lead is also investigated. The models were designed in conjunction with future experimental work to provide comparison data between theory and experiment., Department of Energy, Livermore, CA 94950, Outstanding Thesis, Lieutenant, United States Navy, Approved for public release. Distribution is unlimited.

Extensive use of Unmanned Underwater Vehicles (UUVs) and remote equipment in future Naval operations leads to an energy logistics challenge for their rechargeable batteries. A solution to this challenge is a distributed network of renewable power sources detached from mainland power grids. One potential solution is Benthic Microbial Fuel Cell (BMFC) devices. BMFCs must be optimized and upscaled to produce power at relevant scales. 3-D printing is a promising manufacturing method to achieve scalable BMFC devices. In this thesis, we devised, developed, and optimized a protocol for clearance of microfluidic channels using square cross-sections embedded within PolyJet 3-D-printed chips. The developed protocol demonstrated 75% volumetric clearance of the embedded channels. The protocol was then used to clear channels with T-shaped cross-sections, which were used to produce an experimental proof of principle for self-assembled wiring within the microchannels due to fluidic surface tension. These advancements have opened the door to embedded wiring for 3-D printed biofuel cells and other microfluidic technologies. When perfected and manufactured at scale, biofuel cells could provide a solution to the critical logistics problem of recharging UUVs and similar equipment employed in remote maritime environments, thereby making an exceptional contribution to the U.S. Navy, U.S. national security, and the related research fields., Office of Naval Research, Arlington, VA 22203, Lieutenant, United States Navy, Approved for public release. Distribution is unlimited.

Solid propellants are used mainly in military missiles because they provide sufficient high thrust and resist accidental detonation, especially during storage. The latest version, the NATO Evolved Sea Sparrow Missile (ESSM), uses Hydroxyl-Terminated Polyether (HTPE) as a solid propellant binder. This thesis examines an entirely different acetal-based polyurethane propellant binder, Hydroxyl-Terminated Polyacetylene (HTPA), which has been patented since the 1960s but has not been used. In addition, the literature on HTPA is scarce. For this reason, in this thesis, HTPA was synthesized and compared with different HTPE samples to conclude if it can replace the current ESSM binder in the future. The synthesis of HTPA derived from the chemical compound of Butynediol with Paraformaldehyde was achieved with a reasonably satisfactory reaction yield. Moreover, the mechanical test results revealed that the HTPA polymer with Hydrogenated MDI (HMDI) as a curative exhibited the lowest deformation rate of all other polymers. Thus, the polymer HTPA with HMDI as a curing agent seems to perform better mechanical properties than HTPE. Finally, mechanical properties analysis showed that the HTPA-based polymers present much higher stress values than HTPE. Therefore, it appears that HTPA polymers behave more strongly and stiffly than their HTPE counterparts, a prerequisite for further research into acetal-based binders as a potential substitute for polyether-based polyurethane binders., Plotarhis, Hellenic Navy, Approved for public release. Distribution is unlimited.

Naval Special Warfare (NSW) operators are required to dive into cold waters for a prolonged time to infiltrate demanding environments. While underwater vehicles give the opportunity for longer infiltration ranges and deeper dives, the diving suit, which protects the diver from hypothermia, becomes the most essential diving equipment for the success of the mission. Although the first wetsuit was made in the 1950s, there has been no significant advancement in the neoprene material until recently, and the shrinking neoprene air pockets under depth pressure decrease the thermal insulation of the wetsuit and affect the diver’s buoyancy. To overcome this downside, the K-Suit Mk.4 prototype was created to give NSW operators an alternate diving wetsuit option with superior ergonomics, depth-independent thermal insulation and buoyancy, and possible sound protection. This wetsuit has a base layer of 3mm neoprene and two layers of composite materials. The first composite layer is composed of 8mm-thick glass microspheres mixed with a polymer and the second is thinner and forms solid ceramic beads coupled with the same polymer. Six experimental dives were carried out to gather temperature and pressure data. The data were analyzed, and the result is the K-Suit has the ability to outperform the traditional 7mm diving wetsuit specifications that NSW typically uses., ONR, Plotarhis, Hellenic Navy, Approved for public release. Distribution is unlimited.

This research performs trade-off analysis on attacker-defender swarm engagements to compare the relative efficiency of factors governing swarm behavior, namely targeting algorithms and individual drone parameters. In particular, we examined algorithms developed for the Service Academies Swarm Challenge (SASC), a live-fly drone swarm exercise of swarm-on-swarm engagements. We performed this analysis with dynamic swarm simulations that permitted variations in swarm composition and behavior. This allowed us to confirm the qualitative results of swarm performance from the SASC. In addition, we used scaling analysis methods to perform quantitative trade-off analysis and developed functional forms to assess defender swarm fitness. Our results provide a framework for studying more complex swarm behaviors in follow-on research., Office of Naval Research/CRUSER, Lieutenant, United States Navy, Approved for public release. Distribution is unlimited.

This research further improves previous designs of depth-independent thermal insulation K-suits. It has already been proven that a K-suit (using a generic shape design that can adapt to most body shapes, constructed by a glass microsphere elastomer mixture) provides greater thermal protection without sacrificing ergonomics, unlike the thicker neoprene suits. This project improves this wetsuit by doubling the amount of insulation, improving the efficiency of the production work phase, and improving construction of the wetsuit design. Typically, wetsuit designs have an inverse relationship between thermal protection and ergonomics of the wetsuit, which severely hinders the working diver over the recreational diver. This project breaks that mold and creates a more ergonomic and better insulated wetsuit that will make the working diver warmer, safer, and more productive., ONR, Lieutenant, United States Navy, Approved for public release. Distribution is unlimited.

Technological advancements in electronic device scaling has led to the use of smaller spacecraft that can travel at higher speeds and lower costs associated with launch weight and propulsion. Traditional counter-radiation methods for space electronics involve hardened chip designs that negate the benefits of using smaller, lighter spacecraft. A self-healing counter-radiation approach, using a micro-heater to thermally anneal commercial-off-the-shelf (COTS) chips, is an attractive alternative due to performance enhancement and reduced cost and weight. In this research, the degradation of COTS transistors via gamma radiation and their subsequent recovery in the laboratory is experimentally proven. Through an iterative process, an annealing protocol is developed that successfully recovered damaged bipolar junction transistors (BJT) exposed to 5–10 Mrad radiation doses in approximately two hours at 200°C. Additionally, finite element modeling is used to create an annealing micro-heater, adjust heater parameters to optimize performance, and explore heater integration with a ceramic chip package, lid, and transistor. The annealing protocol and model results in this research provide the foundation for future self-healing efforts using more complex electronics, such as logic units. Furthermore, this research can serve to enhance the robustness of space electronics for future space missions executed by the DOD and subordinate organizations, such as the U.S. Space Force., DoD Space, Captain, United States Army, Approved for public release. Distribution is unlimited.

The Department of Defense relies on many platforms that require inertial sensors to operate in Global Positioning System (GPS)–compromised environments to provide or verify navigational data. The current generation of sensors in use are subject to sensitivity limitations and drift errors that can compound significantly over time in GPS-contested areas. Inertial sensors based on atom interferometers could provide navigational data that is significantly more accurate and less prone to drift (and therefore navigational errors). This research builds upon previous work (Manicchia in 2020, Gervis in 2021) in which an atomic interferometer was constructed and studied. In this thesis, I demonstrate a path toward making inertially sensitive measurements with this apparatus. In contrast to the previous work, I use counter-propagating Raman fields that can achieve inertial sensitivity. However, these Raman fields are sensitive to non-trivial transverse velocities of our atom beam. I demonstrate a method to reduce these transverse velocities using an optical molasses, but do not pursue this in the apparatus due to spatial considerations. I explore the difference between Ramsey and spin echo spectroscopies, forms of atomic interference, in co- and counter-propagating configurations, the second of which is inertially sensitive. I also demonstrate that interference is still visible in the counter-propagating geometry, laying the foundation for a fully inertially sensitive interferometer.

Expeditionary Advanced Base Operations (EABO) will require significant coordination across multiple branches to ensure sufficient sustainment capabilities, especially to meet the high energy demands for these operations. One solution to meet the extraordinary energy demands of EABO is through hydrogen production with a small modularized, lead-cooled fast reactor (LFR). Hydrogen could then be used as feedstock to produce synthetic hydrocarbons that could supplement conventional fuel through a Fischer-Tropsch process. This thesis explores the various hydrogen production methods compatible with an LFR in an EABO environment. An analysis was conducted for each method to determine the most efficient operating conditions based on the typical operating ranges of a reference LFR. This analysis determined that a Hybrid Thermochemical Electrolysis process was the most effective method for hydrogen production when paired with an LFR and using a Supercritical Carbon Dioxide (S-CO2) Brayton cycle for energy conversion. It was also realized that the lack of testing performed with hybrid processes makes the feasibility of this technology being implemented promptly less likely. However, polymer electrolyte membrane (PEM) electrolysis was also found to be a very effective hydrogen production method and is a mature technology with commercially available options already existent that could meet the U.S.’s needs.

Atom interferometer measurements are affected by the amount of quantum noise from the laser used to detect atoms. To improve the quantum limited sensitivity of interferometers, there needs to be a way to reduce the amount of quantum noise. Light is composed of two quadratures, where the product of the noise in each quadrature cannot be below a minimum threshold set by the Heisenberg Uncertainty Principle. However, the noise in one quadrature can be reduced at the expense of the other. This form of light is referred to as “squeezed light.” Squeezed light can be produced using four-wave mixing (FWM). Electromagnetically induced transparency (EIT) is an interference phenomenon that occurs when a three-level atom is driven by a coherent field that makes a non-linear medium transparent to the probing field and holds a great deal of similarities to FWM. This thesis developed a theoretical framework that describes the measurement of atomic states and associated noise when quantum light is used to drive the atom and lays the groundwork to produce squeezed light through developing an experiment to produce EIT, as well as discussing the similarities between EIT and FWM to create and further study FWM for improved atom interferometry.

Quantum key distribution (QKD) is a method of secure key distribution which provides protection against the tampering and interception of information. Following the Bennet-Brassard 1984 (BB84) protocol of QKD, we select randomly from a set of bases in which to produce polarized photons and send the photons to a receiver, who measures them in a basis randomly selected from the same set. The fact that quantum mechanics prohibits the exact copying of a photon ensures that any eavesdropper who intercepts, measures, and attempts to pass the photons on to the receiver will be unable to faithfully reproduce that signal. The presence of the eavesdropper can then be detected, prior to any exchange of information, by an examination of the error rate between portions of the keys generated by the sender and receiver. Using a biphoton source, we have constructed a QKD system for use in research towards naval applications., Lieutenant, United States Navy, Approved for public release. Distribution is unlimited.

Optical turbulence impacts the performance of laser weapons and laser communication by disrupting the focus of the laser beam. It is important to characterize the turbulence along the beam path in order to predict the performance of these systems. Unfortunately, the equipment needed to measure optical turbulence is delicate. A previous thesis found that the turbulence can be estimated using machine learning regression analysis trained on simple atmospheric measurements that can be made with more robust instruments. Machine learning regression analysis is a powerful tool to model complex phenomena with no clear analytical relationship, although extensive data sets are required to train the machine learning model. For this thesis, we measured optical turbulence and various atmospheric parameters (air temperature, humidity, solar flux, etc.) over many months. Using measured atmospheric parameters as inputs, we developed an ensemble of bagged trees regression model with optical turbulence as the response. Overall, this model showed good agreement with the measured values of turbulence. This indicates turbulence could be predicted using these more robust instruments coupled with a machine learning regression model., Office of Naval Research, Arlington, VA 22203-1995, Plotarhis, Hellenic Navy, Approved for public release. Distribution is unlimited.

Current ceramic body armor consists of a monolithic front plate. These monolithic plates have performance degradation issues from fracture due to both multi-hit damage and mishandling. In addition, the plates provide no flexibility. Ceramic spheres have a demonstrated higher mass efficiency compared to monolithic ceramic plates against spherical projectiles and avoid current issues found within monolithic ceramic plates. Within this thesis, rifled projectiles were used to assess the performance and mass efficiency of single-layer ceramic sphere matrices as a front face armor system. Ceramic sphere armor systems varied by ceramic chemistry, diameter size, and encapsulation. A 25.4 mm smooth bore light gas gun was used in combination with a high-speed video camera to capture the initial and terminal velocity after ballistic impact of a 0.30 caliber M2AP projectile with the front face ceramic armor systems. Both the total work and mass efficiency were calculated and compared between both ceramic spheres and monolithic ceramic plate body armor systems., WASHINGTON, DC, 20301, Lieutenant, United States Navy, Approved for public release. Distribution is unlimited.

Naval Special Warfare (NSW) operators are required to dive into cold waters for a prolonged time to infiltrate demanding environments. While underwater vehicles give the opportunity for longer infiltration ranges and deeper dives, the diving suit, which protects the diver from hypothermia, becomes the most essential diving equipment for the success of the mission. Although the first wetsuit was made in the 1950s, there has been no significant advancement in the neoprene material until recently, and the shrinking neoprene air pockets under depth pressure decrease the thermal insulation of the wetsuit and affect the diver’s buoyancy. To overcome this downside, the K-Suit Mk.4 prototype was created to give NSW operators an alternate diving wetsuit option with superior ergonomics, depth-independent thermal insulation and buoyancy, and possible sound protection. This wetsuit has a base layer of 3mm neoprene and two layers of composite materials. The first composite layer is composed of 8mm-thick glass microspheres mixed with a polymer and the second is thinner and forms solid ceramic beads coupled with the same polymer. Six experimental dives were carried out to gather temperature and pressure data. The data were analyzed, and the result is the K-Suit has the ability to outperform the traditional 7mm diving wetsuit specifications that NSW typically uses.

Body armor for military applications uses a composite system incorporating a monolithic ceramic front face plate backed by an Ultra High Molecular Weight Polyethylene (UHMWPE) textile system that offers a high mass efficiency. Issues with the current system include mobility, fracture and multi-hit performance degradation. It has been demonstrated that ceramic spheres have a higher mass efficiency as compared to monolithic ceramic tiles when applied against 3/8” chromium steel projectiles and 0.30 caliber M2AP projectiles. Within this study, the penetration resistance performance of two selected projectiles (AK-47 and M80) were studied against multiple front face ceramic armor systems. The back face deflection was measured using high-speed video to determine both in-plane and out-of-plane propagation. This data was correlated with load cell force measurements to provide a means to measure penetration resistance performance through determination of the work performed by the 80-layer UHMWPE backing with the selected front face ceramic systems. This work will enable a higher level of performance fidelity and enable optimized front face ceramic armor systems., Washington, DC, 20301, Lieutenant, United States Navy, Approved for public release. Distribution is unlimited.

Solid propellants are used mainly in military missiles because they provide sufficient high thrust and resist accidental detonation, especially during storage. The latest version, the NATO Evolved Sea Sparrow Missile (ESSM), uses Hydroxyl-Terminated Polyether (HTPE) as a solid propellant binder. This thesis examines an entirely different acetal-based polyurethane propellant binder, Hydroxyl-Terminated Polyacetylene (HTPA), which has been patented since the 1960s but has not been used. In addition, the literature on HTPA is scarce. For this reason, in this thesis, HTPA was synthesized and compared with different HTPE samples to conclude if it can replace the current ESSM binder in the future. The synthesis of HTPA derived from the chemical compound of Butynediol with Paraformaldehyde was achieved with a reasonably satisfactory reaction yield. Moreover, the mechanical test results revealed that the HTPA polymer with Hydrogenated MDI (HMDI) as a curative exhibited the lowest deformation rate of all other polymers. Thus, the polymer HTPA with HMDI as a curing agent seems to perform better mechanical properties than HTPE. Finally, mechanical properties analysis showed that the HTPA-based polymers present much higher stress values than HTPE. Therefore, it appears that HTPA polymers behave more strongly and stiffly than their HTPE counterparts, a prerequisite for further research into acetal-based binders as a potential substitute for polyether-based polyurethane binders.

High-power microwave (HPM) weapons use electromagnetic waves to neutralize electronic hardware, making them an ideal candidate to defeat drones. The effectiveness of HPM weapons is determined by their intensity, their spatial effect profile, and the mobility or spatial location of the HPM weapon platforms. NPS researchers have developed modeling approaches to perform mission-level studies of effects of such weapons, including determination of optimal tactics, determination of minimum platform specifications for mission success, and trade-off analysis between parameters.

A key component of battle space awareness is direction of arrival (DoA) determination of gunshots. In the initial stages of an engagement, quick and reliable DoA determination enhances a Marine’s ability to execute the observe-orient-decide-act (OODA) loop, increasing chances of survival and mission success. Naval Postgraduate School (NPS) has developed a novel, biomimetic acoustic sensor modeled after the auditory system of the Ormia Ochracea fly. This microelectromechanical system (MEMS)-based directional sound sensor, which consists of two wings connected to a substrate using two torsional legs in the middle, is well documented in previous NPS theses. Each sensor has a uniform dipole beam pattern. By combining two crossed MEMS sensors (crossed-dipoles) with an omni-directional microphone, 360° DoA determination can be fully resolved. The objective of this thesis is to evaluate, optimize, and develop DoA estimators for gunshots in the time- and frequency-domain, specifically for the crossed-dipoles sensors plus an omni-directional microphone configuration., ONR, Arlington, VA 22203, Outstanding Thesis, Ensign, United States Navy, Approved for public release. Distribution is unlimited.

The use of strontium in an atom interferometer presents the opportunity to perform detailed measurements of gravitational fields, rotation rates, and clock transitions as well as other natural phenomena. Strontium can be particularly effective in atom interferometry experiments for two reasons. The first is that the intrinsic magnetic properties of strontium result in less sensitivity of the transition frequencies to magnetic noise, allowing for better measurements. Second, strontium atoms can be cooled to a lower temperature just through ordinary Doppler cooling than other atoms typically used in interferometry (e.g., rubidium). A lower temperature means less initial kinetic energy and hence lower spatial dispersion over the course of an experiment. A magneto-optical trap consisting of two primary cooling lasers and two repump lasers cools and confines strontium atoms for use in the interferometer. This thesis focuses on the repump lasers and includes the design and performance of the optical system that frequency stabilizes each laser. The system demonstrated the ability to simultaneously frequency lock the two repump lasers to the degree necessary to form a strontium magneto-optical trap., Army Research Office, Research Triangle, NC, 277703, Outstanding Thesis, Lieutenant Commander, United States Navy, Approved for public release. Distribution is unlimited.

Polybenzoxazole fibers (PBO, commercially trademarked as Zylon) were once used as an alternative to ultra-high molecular weight polyethylene (UHMWPE) fibers in body armor systems. PBO fibers exhibit a high Young’s modulus, excellent thermal stability, and tensile strength (nearly twice that of Kevlar), but the physical properties severely degrade when exposed to water. Hydrophobic polymer coatings were applied to PBO fibers and studied for moisture resistance, coating durability, and ballistic performance. Instron tensile testing and a V50 assessment utilizing a light gas gun and 9.525 mm spherical chromium-steel projectiles were conducted on four different textile armor systems, including uncoated PBO weave, uncoated PBO weave exposed to water, polymer-coated PBO weave, and polymer-coated PBO weave exposed to water. Using load cells to measure uni-axial forces, combined with digital image correlation enabling measurement of both in-plane and out-of-plane fiber deflection, stress-strain measurements of the four different textile armor systems were measured and compared. Flex Seal liquid coating proved to be the most effective waterproof coating in terms of consistent hydrophobic performance, flexibility, and ease of application; however, further research is required to refine coating methods as well as collect additional data for the performance of PBO under dynamic loads., http://archive.org/details/effectsofhydroph1094566605, Lieutenant, United States Navy, Approved for public release. distribution is unlimited

Atom interferometers depend on light/matter interactions and are extremely sensitive sensors capable of being employed as accelerometers, rotation sensors, and gravity and magnetic gradiometers. Typical interferometers use a well-known velocity (generally from atoms launched out of an atomic trap) to interferometrically measure quantities of interest (e.g., acceleration and rotation). This thesis evaluates the effects of atom velocity in an atom interferometer sensor that exists at NPS, which uses a continuous beam of cold rubidium atoms with a narrow but not monochromatic range of velocities passing through continuous laser fields. The atom’s velocity dictates the interaction time between the atom and laser. However, this combination results in pulse errors due to velocity averaging. One method to counteract these pulse errors uses the so-called counterintuitive laser arrangement—a method known as stimulated Raman adiabatic passage (STIRAP). STIRAP will be shown to be a more robust approach. Starting with the atoms in one of the ground states, all or a portion of the atoms can be transferred to the other ground state in a well-controlled manner. Changes in acceleration and rotation can be sensed with very high precision by a detection laser resulting in applicability as a highly sensitive accelerometer or gyroscope. This project explores experimentally and theoretically the utility of counterintuitive pulse sequences for atom interferometry applications., http://archive.org/details/improvedatominte1094566730, Outstanding Thesis, Lieutenant, United States Navy, Approved for public release. distribution is unlimited

Atom interferometers possess great potential as sensitive and stable acceleration and rotation sensors. Currently, the DoD is interested in leveraging atom interferometry research to improve inertial sensors and develop portable, compact devices based on atom interferometers with strategic-grade performance. Typical atom interferometers measure the acceleration or rotation signal with an on-resonance detection laser field, but these laser fields have inherent noise that degrades the signal-to-noise ratio. The laser noise in one quadrature of the field can be reduced below the so-called shot noise limit at the expense of the other quadrature. Fields with this property are called “squeezed fields.” Although lowering the noise in one quadrature increases noise in the other quadrature (due to Heisenberg’s uncertainty principle), the noise in the other quadrature can be made irrelevant by designing a detection scheme that does not use that quadrature. By reducing light-source noise, atom interferometer measurement precision can be increased. This thesis aims to establish the groundwork for creating squeezed light to be used for the detection of atoms in the ground or excited state of the NPS Atom Interferometry Laboratory atom interferometer., Lieutenant, United States Navy, Approved for public release. distribution is unlimited

Free space optical (FSO) communication technology is increasingly used for both commercial and military purposes. For military communication that requires fast, secure, and reliable transmission of information, the benefits of using FSO technology are important. However, there are some inherent limitations, especially due to environmental conditions such as turbulence, that can significantly affect the performance of FSO communication systems. Since turbulence plays a critical role in FSO systems, the purpose of this thesis is to compare different experimental and theoretical methods for estimating turbulence in a maritime environment. This analysis is achieved by measuring meteorological parameters using a local weather station and then using that data to calculate (using machine learning regression analysis) the refraction structure parameter that indicates the severity of turbulence. Also, the impact of turbulence on the signal-to-noise ratio (SNR) for a notional FSO system is estimated to show that even moderate amounts of turbulence can significantly reduce the SNR., Lieutenant Commander, Hellenic Navy, Approved for public release. distribution is unlimited

New hypersonic vehicles will operate inside the atmosphere through flight and are now subjected to increase atmospheric particulates exposure primarily composed of Calcia-Magnesia-Alumina-Silicate (CMAS) and is known as CMAS attack. CMAS attack affects thermal and environmental barrier coatings and is an ongoing problem for gas turbine engines (GTE). New materials are needed to withstand high temperatures while resisting CMAS attack. This thesis aims to characterize CMAS interaction with the two candidates for hypersonic applications: hafnium and zirconium diboride. Both ceramics were mixed with CMAS and then placed in isothermal holds at 1000–1600°C between 1–100 hours of exposure. The samples were then analyzed via transmission/scanning electron microscope (T/SEM), energy dispersive spectroscopy (EDS), and x-ray diffraction (XRD) to identify new phases. At all temperatures and durations, both diborides oxidized and produced MO2(M=Hf/Zr). For durations less than an hour regardless of temperature, both diborides reacted weakly or did not react with the CMAS. For all other durations and temperatures, the silicate in the CMAS reacted with MO2 and produced MSiO4 but then revert back into their oxide and SiO2 at 1600°C. Further studies will look at bulk pucks of MB2 for better characterization of CMAS infiltration on both diborides under hypersonic conditions using a rig burner., Lieutenant, United States Navy, Approved for public release. Distribution is unlimited.

Ring laser gyroscope (RLG)-based inertial navigation systems (INS) form the basis of navigation systems. While RLG-based systems have an improvement in accuracy and reliability over their traditional mechanical gyroscope-based forebearers, they suffer inaccuracies and drift in detecting acceleration and rotation that lead to errors. INS compute their current position by integrating equations of motion from their last position, and therefore any error can quickly compound. Atomic beam gyroscopes offer a major advantage over current ring laser-based systems in that they can have a potential increased accuracy of several orders of magnitude, which results in far more accurate navigation over time while in operation. By linking gyroscope parameters to atomic parameters (which, by definition, do not change over time), atomic gyroscopes have low drift. The test bed at Naval Postgraduate School uses one atomic beam that can detect but cannot distinguish between rotation and acceleration. This research involves the addition of a second anti-parallel beam path to the apparatus with enhanced optical characteristics and changes to the detection and state lasers to allow the apparatus to distinguish between the two forms of motion. The velocity, divergence, and optimal power settings of the second atomic beam are characterized, and the changes to the detection and state lasers to allow for simultaneous bi-directional measurement are discussed., Lieutenant-Commander, Royal Canadian Navy, Approved for public release. Distribution is unlimited.

This research aims to produce an improved wetsuit designed to insulate divers at low temperatures and increased depths. Military divers currently use 7 mm thick neoprene wetsuits, which lose thermal performance at high depths due to compression of the material. This poses a serious problem to the safety of Navy divers and mission success. An improved wetsuit with better thermal insulation at high depths would improve mission duration, capabilities, and diver safety. Our wetsuit has a 3 mm neoprene base, with composite casts covering the chest, abdomen, back, and thighs, similar to plated armor. The composite material consists of 3M K1 glass microspheres embedded into a Sylgard 184 silicone elastomer. This provides better thermal insulation than the neoprene material and does not contract at increasing depths in the water. It also provides better mobility along the joints. The proof of concept of this design has been explored in previous projects, and the purpose of this research is to complete the suit with forearm, bicep, and shin panels and to gather extensive data comparing the composite wetsuit to 7 mm wetsuits. We use automated data loggers, external and internal to the suits, to collect temperature and pressure data in field tests. Further testing is required to find thermal improvement. Ideally, the final composite wetsuit will increase thermal insulation for the diver, while the thin material around the joints will provide increased mobility for mission success., Ensign, United States Navy, Approved for public release. Distribution is unlimited.

The Navy is interested in obtaining alternate methods of navigation for Global Positioning System (GPS) denied environments, and one candidate is precision inertial navigation using atom interferometers. A good method of modeling the behavior of a group of atoms in an interferometer is to use the Wigner distribution. In atom interferometry, the distribution of a set of atoms starts with a well-defined distribution in position and momentum space (usually Gaussian), but their positions spread more rapidly than their momenta, forming an ellipse in phase (Wigner) space. However, this ellipse can rotate as it propagates, revealing new quantum phenomena. This project models the behavior of an atom in an interferometer and investigates the underlying physics of the Wigner ellipse rotation. Although no discoveries were made, the Wigner phase space model succinctly communicates the dynamics of the atoms inside the interferometer., Ensign, United States Navy, Approved for public release. Distribution is unlimited.

Optical turbulence impacts the performance of laser weapons and laser communication by disrupting the focus of the laser beam. It is important to characterize the turbulence along the beam path in order to predict the performance of these systems. Unfortunately, the equipment needed to measure optical turbulence is delicate. A previous thesis found that the turbulence can be estimated using machine learning regression analysis trained on simple atmospheric measurements that can be made with more robust instruments. Machine learning regression analysis is a powerful tool to model complex phenomena with no clear analytical relationship, although extensive data sets are required to train the machine learning model. For this thesis, we measured optical turbulence and various atmospheric parameters (air temperature, humidity, solar flux, etc.) over many months. Using measured atmospheric parameters as inputs, we developed an ensemble of bagged trees regression model with optical turbulence as the response. Overall, this model showed good agreement with the measured values of turbulence. This indicates turbulence could be predicted using these more robust instruments coupled with a machine learning regression model.

Current ceramic body armor consists of a monolithic front plate. These monolithic plates have performance degradation issues from fracture due to both multi-hit damage and mishandling. In addition, the plates provide no flexibility. Ceramic spheres have a demonstrated higher mass efficiency compared to monolithic ceramic plates against spherical projectiles and avoid current issues found within monolithic ceramic plates. Within this thesis, rifled projectiles were used to assess the performance and mass efficiency of single-layer ceramic sphere matrices as a front face armor system. Ceramic sphere armor systems varied by ceramic chemistry, diameter size, and encapsulation. A 25.4 mm smooth bore light gas gun was used in combination with a high-speed video camera to capture the initial and terminal velocity after ballistic impact of a 0.30 caliber M2AP projectile with the front face ceramic armor systems. Both the total work and mass efficiency were calculated and compared between both ceramic spheres and monolithic ceramic plate body armor systems.

Quantum key distribution (QKD) is a method of secure key distribution which provides protection against the tampering and interception of information. Following the Bennet-Brassard 1984 (BB84) protocol of QKD, we select randomly from a set of bases in which to produce polarized photons and send the photons to a receiver, who measures them in a basis randomly selected from the same set. The fact that quantum mechanics prohibits the exact copying of a photon ensures that any eavesdropper who intercepts, measures, and attempts to pass the photons on to the receiver will be unable to faithfully reproduce that signal. The presence of the eavesdropper can then be detected, prior to any exchange of information, by an examination of the error rate between portions of the keys generated by the sender and receiver. Using a biphoton source, we have constructed a QKD system for use in research towards naval applications.

Body armor for military applications uses a composite system incorporating a monolithic ceramic front face plate backed by an Ultra High Molecular Weight Polyethylene (UHMWPE) textile system that offers a high mass efficiency. Issues with the current system include mobility, fracture and multi-hit performance degradation. It has been demonstrated that ceramic spheres have a higher mass efficiency as compared to monolithic ceramic tiles when applied against 3/8” chromium steel projectiles and 0.30 caliber M2AP projectiles. Within this study, the penetration resistance performance of two selected projectiles (AK-47 and M80) were studied against multiple front face ceramic armor systems. The back face deflection was measured using high-speed video to determine both in-plane and out-of-plane propagation. This data was correlated with load cell force measurements to provide a means to measure penetration resistance performance through determination of the work performed by the 80-layer UHMWPE backing with the selected front face ceramic systems. This work will enable a higher level of performance fidelity and enable optimized front face ceramic armor systems.

Low iron soda-lime glass (SLG) is a low-cost, bulk manufactured, commercially available off-the-shelf glass with high quality clarity and transparency, and superior percentage visible light transmittance with color that is resistant to yellowing over time. SLG has been used for various military applications and for the past 15 years, has been studied and viewed with borosilicate as ideal choices of glass for transparent armor applications. Prior research has demonstrated that SLG experiences fractoluminescence (FL), or the emission of photons during rapid dynamic fracture. Contested theories for the cause of FL include thermal origins, relaxation of non-bridging oxygen hole centers, and even Cherenkov radiation. This thesis investigated whether FL can be observed in SLG via near-hypervelocity kinetic impact utilizing a 40 mm powder gun. Target systems include both planar impact for standard diagnostics and gap-sealed cylindrical chambers to both minimize noise from external light and enable post-test analysis of impacted glass. A comparative analysis was conducted against borosilicate glass, which has no FL properties. Unique FL emission bands were observed during near hypervelocity impact of SLG at 423 nm (2.9 eV) at the frame of impact and 555 nm (2.2 eV) for the duration of fracture. Using a grey body spectral exitance emission spectra fit, a fracture emission temperature of 3200 K was calculated that does not support the theory of Cherenkov radiation as the cause of FL.

When small, macroscopic, solid particles (like glass beads or grains of starch) are immersed in Newtonian fluids (like water or glycerol), the resulting material demonstrates solidification under sudden driving, like from intrusion of an object above a threshold velocity. The physical means for this effect are not fully understood. One mechanism that has been proposed involves hydrodynamic pressure: the fluid must flow through the pore structure between particles as the material deforms. Consistent with this picture, the viscosity of the fluid has been identified as a contributing factor to this resistance. The ability to control the viscosity in real time would allow for maximum resistive pressure when needed and then for low resistance in between periods of high driving. One possibility for accomplishing this is using ferrofluids. Ferrofluids contain molecules of iron coated in a surfactant and suspended in a solvent. This mixture is capable of changing its viscosity when a magnetic field is present. I will explore the mechanical properties, including the impact resistance, where the simple Newtonian fluid is replaced with a ferrofluid. I compare this with existing data in literature and from previous projects in our group. I find that the experimental results match predicted theory to a point and then data suggests that other forces counteract these predictions. I find that ferrofluids are capable of creating a tunable complex fluid mixture and warrant further research., ONR, Major, United States Army, Approved for public release. distribution is unlimited

Systems of sub-millimeter solid particles immersed in a simple fluid can exhibit a dramatic increase in flow resistance when they are rapidly sheared, often called discontinuous shear thickening (DST). A related process is impact-induced solidification, which occurs when an intruder is driven into a particle-fluid mixture. The resultant hardening is sufficient to dampen the movement of the intruder to essentially stop it in a distance much shorter than it would in other fluids. However, the fundamental physical processes that give rise to these behaviors are not well understood. An improved description would have several military applications, such as under-vehicle armor and pipe jacketing. It also could provide a better understanding of how mines interact with wet soils. This thesis presents a fundamental experimental and theoretical study of low-speed impacts into systems of glass beads of varying sizes mixed with water. Our results show that current models fail to capture many aspects of the behavior (e.g., how the peak stresses during impact depend on the initial impact speed and the particle diameter), suggesting that new theoretical descriptions are needed., Lieutenant, United States Navy, Approved for public release. distribution is unlimited

Polybenzoxazole fibers (PBO, commercially trademarked as Zylon) were once used as an alternative to ultra-high molecular weight polyethylene (UHMWPE) fibers in body armor systems. PBO fibers exhibit a high Young’s modulus, excellent thermal stability, and tensile strength (nearly twice that of Kevlar), but the physical properties severely degrade when exposed to water. Hydrophobic polymer coatings were applied to PBO fibers and studied for moisture resistance, coating durability, and ballistic performance. Instron tensile testing and a V50 assessment utilizing a light gas gun and 9.525 mm spherical chromium-steel projectiles were conducted on four different textile armor systems, including uncoated PBO weave, uncoated PBO weave exposed to water, polymer-coated PBO weave, and polymer-coated PBO weave exposed to water. Using load cells to measure uni-axial forces, combined with digital image correlation enabling measurement of both in-plane and out-of-plane fiber deflection, stress-strain measurements of the four different textile armor systems were measured and compared. Flex Seal liquid coating proved to be the most effective waterproof coating in terms of consistent hydrophobic performance, flexibility, and ease of application; however, further research is required to refine coating methods as well as collect additional data for the performance of PBO under dynamic loads.

Our objective is to construct a depth-independent, full-body wetsuit that insulates the human body effectively regardless of the temperature of the ambient seawater to facilitate safer and more efficient swimming, diving, and underwater operations. To do so, we produced 3D scans of the human body, segmented the scans through the use of software to maximize ergonomics, and then converted the segments into digital mold patterns, which were 3D printed in polycarbonate. The molds were used to cast a composite consisting of hard hollow microspheres embedded in thermally cured carrier silicone elastomer. The composite casts were tested for ergonomic mobility and adjusted as needed. We also devised a method to attach the composite components to a commercial neoprene suit to be used as a waterproof bodyglove carrier, thereby producing the new segmented diver suit. Future work will assemble the full suit and test it under field conditions.

Light Detection and Ranging (LiDAR) technology has various useful applications, such as in surveying tasks. This study continues research previously conducted at the Naval Postgraduate School by Andrew S. Davis, and documented in his thesis, “Forestry Identification with LiDAR Waveform and Point Clouds.” The present study, which aims to evaluate the classification capability of LiDAR systems over various tree species in a particular area of interest, collected sample data over Point Lobos State Park, California. The data set was separated into two categories, aerial platform and ground survey. The aerial platform consisted of an Optech Titan system and Airborne Hydrography AB Chiroptera system (AHAB). Analysis was performed by comparing the results from the ENVI software classifier and the actual location of tree species from ground surveying. The study also extracted the features of waveforms from each tree species and used these features to distinguish them from among other samples of tree species and their surrounding environment, such as roads and trails. The classifications were done by the classifier tools provided in ENVI (K-means, Spectral Angle Mapper, and Support Vector Machine). The results showed that waveform data can accurately distinguish class samples. The analysis also pointed out that the most common error occurred when classes had a narrow gap in data values and shared similar pulse shapes., http://archive.org/details/terraincategoriz1094564073, Lieutenant Junior Grade, Royal Thai Navy, Approved for public release; distribution is unlimited.

It is well known that the South Pacific coasts have significant illegal activities such as drug trafficking and forbidden fishing. The government of Peru is concerned about these issues, delegating the responsibility of suppressing the problems to the Peruvian Navy. The Peruvian Navy conducts Maritime Interdiction Operations, and in recent years, specialized patrol boats have been used for easier and more direct interdictions, but they have limited velocity and engagement range. UAV-HEL (Unmanned Aerial Vehicle based High Energy Laser) weapons would overcome those limitations potentially enabling long-range engagements without damaging people or cargo. This research establishes requirements for size, weight and power for a UAV-based HEL to engage and effect damage on a target. Modeling tools are used to estimate irradiance on the target in various Peruvian coastal conditions and engagement geometries to estimate the required dwell time to damage or disable the target. Based on the results, the viability of a UAV-HEL for this application is addressed., http://archive.org/details/requirementsforp1094564118, Ensign, Peruvian Navy, Approved for public release; distribution is unlimited.

The purpose of this research is to determine if microfluidic technology can be used as a renewable energy application to determine optimization for increased power of Benthic Microbial Fuel Cells (BMFC). A microfluidic chip-based BMFC was designed to evaluate bacterial electricity at microscale distances. The system could be used to optimize biological parameters, geometry, and electrode scaling towards increased power. The polydimethylsiloxane (PDMS) chip is built using elastomer microfluidics to provide biologically inert microfluidic confinement of the bacteria. The microelectrode matrix patterned onto glass substrate is based on the binary fractal H-architecture, which captures the charge without location bias and conducts it to the outside circuit. The results show up to ~120 mW/m^2 average power output density, non-optimized. This encouraging output shows that this device and associated technique are a major step forward for renewable power systems for maritime environments and demonstrates that microfluidics can be considered for power production. This can become a standardized test platform for future MFC research and optimized for power production. Once optimized, one chip can serve as a unit device in an array comprising a large-scale renewable power source and integrate continuous or periodic food sources., NAVWAR (SSC-PAC), http://archive.org/details/outputpoweroptim1094564035, Outstanding Thesis, Lieutenant, United States Navy, Approved for public release; distribution is unlimited.

Acoustic noise interferometry uses long time series recordings of ambient and shipping noise, which are concurrently captured at two locations, to measure the acoustic Green’s function. With this technique, each hydrophone becomes a virtual acoustic transceiver—a combination of a source and a receiver—which can be used for passive acoustic remote sensing of the ocean. Compared to active techniques, passive remote sensing greatly reduces costs and allows for undetected, surreptitious monitoring of acoustic non-reciprocity, a sensitive measure of the velocity of oceanic currents. Using data obtained in the 2012 Florida Straits Noise Interferometry Experiment, this work investigated the feasibility of retrieval of the depth-dependence of the current velocity from the passively measured non-reciprocity of normal mode travel times in a shallow-water waveguide. It was found that measurements of the current-induced non-reciprocity of normal mode group speeds with errors up to 0.2 m/s will allow for inversion of the vertical current velocity profile with oceanographically relevant vertical resolution and accuracy. Additionally, passive measurements of acoustic non-reciprocity at frequencies below 80 Hz at ranges of about 50 times the ocean depth are sufficient for retrieval of the current velocity profile in shallow water. Thus, the technique investigated in the thesis can now be applied to field data, like those acquired in previous measurements in the Florida Straits., National Science Foundation, Lieutenant, United States Navy, Approved for public release. distribution is unlimited

Reactive material warhead cases have the potential to greatly increase ordnance lethality by the addition of metal combustion, to explosive and fragmentation effects. Efficient combustion of the reactive metal relies on adequate dispersion of fine metal debris following detonation or impact. This thesis examines the use of tin as a soft binder for cold-isostatically pressed aluminum powder. The tin can potentially shock melt under rapid loading, increasing the dispersion of the aluminum by dynamically creating liquid failure regions. Several mechanical tests, including Split-Hopkinson Pressure Bar compression and Brazilian tension tests, gas gun impact tests, and three-point bend tests, as well as scanning electron microscopy, were used to determine dynamic strength, fragmentation properties, fracture toughness, and other mechanical properties of aluminum-tin composites of varying composition. Samples with lower tin content (5–10% by volume) were highly homogeneous and had low porosity following annealing. However, from a structural standpoint the tin binder results in reductions in strength and toughness compared to a pure pressed-aluminum powder compact. Analysis of the microstructure shows that tin acts as a soft buffer, weakening mechanical properties by preventing interlocking of the aluminum particles during the compaction. The final optimized composite may be useful for enhanced blast thermobaric cases that favor metal dispersion over structural strength., Ensign, United States Navy, Approved for public release. distribution is unlimited

Dense suspensions, which consist of sub-millimeter particles suspended in a Newtonian fluid, undergo a dramatic solidification when subjected to sudden impact, as first described in M.A. Brassard et al.’s article in the 2020 Bulletin of the American Physical Society. The underlying physical mechanisms for this effect are not known. Recently, a class of added mass models has been proposed to explain this phenomenon. These models give direct predictions on the times and magnitudes associated with the peak stresses during impacts, including how these stresses vary with changes to the intruder mass and size. In this thesis, we performed impact experiments in cornflour and water dense suspensions. We varied the size, speed, mass and shape of the intruder and quantified the forces and times via high-speed imaging and acceleration sensors. We used dimensional and scaling analysis to confirm or disprove added mass models, and the aim is for our results to be used to test current theories and help derive future theories to explain impact-induced solidification in dense suspensions., Outstanding Thesis, Major, Canadian Army, Approved for public release. distribution is unlimited

Propulsion and electrical generator systems that utilize fossil fuels experience losses in efficiencies due to waste heat. While there are a number of ways to recover some of this waste heat, this research focuses on a waste heat harvesting system that uses thermoelectric generators (TEGs). TEGs operate via the Seebeck effect, where a temperature difference generates an electric potential. This project consists of three parts. The first part details the steps taken to model the existing water-cooled thermoelectric waste heat harvesting prototype using COMSOL Multiphysics Finite Element Analysis Software. The second part analyzes how well the water-cooled prototype reduces the thermal signature of the gasoline-powered generator’s muffler. This application shows that it could be useful in minimizing asset visibility in the infrared spectrum for expeditionary missions. The last part discusses the design, fabrication, and performance of a passive, air-cooled variant of the thermoelectric waste heat harvesting system. When water-cooled applications are not feasible, as with expeditionary vehicles, having an air-cooled version is possible., Lieutenant, United States Navy, Approved for public release. distribution is unlimited

Lecture demonstrations strongly convey physics concepts and theories. In addition, realistic issues arise that are often not in a model theory. Investigations of lecture demonstrations are published in scholarly journals and are Navy-relevant due to use in classrooms. We investigate two lecture demonstrations. One is the “two-bullet problem,” where a body is released from rest at a height, and another is simultaneously projected at the same height. In a vacuum, it is well known that both strike the floor simultaneously. For the common case of quadratic drag, however, the dropped body is predicted to strike the floor first. We develop a classroom demonstration that clearly exhibits the effect, but the result is suspect because numerical simulations show that the time difference is too small to be clearly discernible. Arguments to resolve the inconsistency are made. In the other demonstration, we describe the first successful parametric excitation of oscillations of the liquid in a U-tube. This is difficult to achieve due to a large drive amplitude threshold. Only a nonlinearity can limit parametric growth and thus lead to steady-state motion, but the observed motion is in the Hooke’s law regime, and the dissipation is very nearly linear. Possible reasons for the steady-state motion are discussed. Also surprising is that the free decay transitions from one damping parameter to a greater one at small amplitudes. We propose a possible reason for this behavior., Ensign, United States Navy, Approved for public release. distribution is unlimited

This thesis uses density functional theory calculations to examine the electronic structure and thermochemistry of a new manganese-perchlorate cluster recently synthesized by Zdilla and coworkers. The cluster is atypical for an energetic material, consisting of tetrazene and perchlorate groups around a cage-like core of manganese and nitrogen. Calculations indicate that the manganese in the cluster core are in an Mn(II) oxidation state and oriented in a high-spin configuration. Ab initio thermodynamic calculations combined with an equilibrium thermochemical code predict a heat of combustion of 2.97 kcal/mol for the cluster in its solid-state structure. The adiabatic flame temperature is predicted to be 1363 K, with Mn primarily reacting to MnO. During combustion in air, the cluster/solvent system is predicted to produce MnO until below 1100 K, where it oxidizes further into MnO2 by reducing NO2.

Thermal protection for divers is critical and needs improvement. The goal is to have a full wetsuit that will insulate the human body from the colder temperature of the water at the depth at which a diver is submerged. I designed, fabricated, and built a fully thermal passive insulation wetsuit using composite material based on microspheres to be able to comfortably fit on a human to minimize restriction while diving and performing duties underwater. During testing in the open ocean, the composite wetsuit was proven to be superior to neoprene wetsuits by several degrees Fahrenheit. This composite wetsuit has a three millimeter neoprene wetsuit for mobility and performs better than a seven millimeter neoprene wetsuit for warmth. By improving divers' thermal protection in water, the composite wetsuit will enhance their job performance and increase the amount of time they can spend underwater.

Atom interferometers depend on light/matter interactions and are extremely sensitive sensors capable of being employed as accelerometers, rotation sensors, and gravity and magnetic gradiometers. Typical interferometers use a well-known velocity (generally from atoms launched out of an atomic trap) to interferometrically measure quantities of interest (e.g., acceleration and rotation). This thesis evaluates the effects of atom velocity in an atom interferometer sensor that exists at NPS, which uses a continuous beam of cold rubidium atoms with a narrow but not monochromatic range of velocities passing through continuous laser fields. The atom’s velocity dictates the interaction time between the atom and laser. However, this combination results in pulse errors due to velocity averaging. One method to counteract these pulse errors uses the so-called counterintuitive laser arrangement—a method known as stimulated Raman adiabatic passage (STIRAP). STIRAP will be shown to be a more robust approach. Starting with the atoms in one of the ground states, all or a portion of the atoms can be transferred to the other ground state in a well-controlled manner. Changes in acceleration and rotation can be sensed with very high precision by a detection laser resulting in applicability as a highly sensitive accelerometer or gyroscope. This project explores experimentally and theoretically the utility of counterintuitive pulse sequences for atom interferometry applications.