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Multi-Parameter Analysis of an Airship for ASW Defense of the US
Get PDFNPS NRP Executive SummaryThis study examined the feasibility of employing a modern airship for antisubmarine warfare (ASW) operations to protect the U.S. coasts. With limited availability of high-cost ASW platforms such as P-8 aircraft and destroyers, especially during wartime, an alternative, lower-cost solution is needed to maintain effective submarine detection and tracking. Drawing on the proven design of 1950s Navy airships (ZPG-2 and ZPG-3), the study proposed to equip a modern airship with towed array and/or dipping sonar systems. The analysis focused on the theoretical ASW capability of such a platform, its potential to reduce the reliance on expendable sonobuoys, and its cost-effectiveness compared to traditional air and sea platforms. Research evaluated various equipment configurations, considering trade-offs between system complexity, detection effectiveness, and time on station. The feasibility of using solar power and battery storage instead of fuel was also assessed, with an emphasis on extending operational range and reducing the risk of counter-detection. Ultimately, the study concluded that a mission-capable ASW airship could represent a viable and economical supplement to existing ASW assets, particularly for homeland defense during resource-constrained scenarios.Approved for public release. Distribution is unlimited.This research is supported by funding from the Naval Postgraduate School, Naval Research Program (PE0605853N/2098). https://nps.edu/nrpChief of Naval Operations (CNO)U.S. Fleet Forces Command (USFLTFORCOM
MULTI-FACTOR ANALYSIS OF HYDRO-MORPHOLOGICAL DYNAMICS IN THE PAJARO RIVER LAGOON
No full textThis study presents a multi-factor analysis of hydro-morphological dynamics in the Pajaro River Lagoon over a 40-year period (1984-2024). Utilizing the Inlet Tracker program, images from Landsat and Sentinel-2 datasets were processed to determine inlet states and quantify channel migration patterns. Validation with in-situ measurements from Helms (2023) demonstrated strong agreement (r = 0.89-0.72).Comparative analysis between extreme water years revealed that river discharge serves as the primary driver of inlet dynamics. WY 2023 exhibited three times greater watershed precipitation and significantly higher average discharge compared to WY 2020, resulting in 300m versus 200m of total channel migration. Wave dynamics remained remarkably similar between years, confirming discharge as the dominant forcing mechanism. However, seasonal analysis revealed a "Goldilocks" effect where moderate discharge combined with significant wave forcing in fall, or minimal discharge allowing consistent wave action in summer, maximizes migration rates.Climate teleconnection analysis revealed weak correlations between watershed precipitation and ENSO (r = 0.11) and PDO (r = -0.04). The study demonstrates that local hydrological conditions are more influential than large-scale climate oscillations in controlling ICOLL morphology at interannual timescales. These findings provide valuable information for military planning or coastal management.Distribution Statement A. Approved for public release: Distribution is unlimited.Outstanding ThesisLieutenant Commander, United States Nav
TOWARD ENHANCED SPACECRAFT ATTITUDE CONTROL: OPTIMAL CONTROL MOMENT GYROSCOPE MANEUVERS UNDER CONSTRAINTS AND FAILURE CONDITIONS
No full textThis thesis examined optimal control strategies for spacecraft reorientation using Control Moment Gyroscopes (CMGs). Three key studies were conducted. First, alternative cost functions were evaluated against the minimum-time solution to assess their impacts on control efficiency, smoothness, and torque authority margin. Second, failure scenarios involving one CMG were analyzed in 4- and 3-CMG configurations, revealing performance degradation and an increased risk of singularity. Third, optimal quaternion trajectories generated via DIDO were tracked using feedback and feedforward controllers in both MATLAB and a hardware-in-the-loop testbed. The results showed that optimal trajectories could be executed with acceptable fidelity in real time. The infinity norm and pseudoinverse regularization improved torque margins without significant time penalties. Across all tests, trade-offs between speed and robustness were observed, emphasizing the need for trajectory shaping in CMG-based spacecraft control.Distribution Statement A. Approved for public release: Distribution is unlimited.Outstanding ThesisLieutenant, United States Nav
ELECTROMAGNETIC INTERFERENCE CHARACTERIZATION AND MITIGATION IN A CLLC-BASED DC TRANSFORMER
No full textThe CLLC resonant converter is a widely adopted design in microgrids and shipboard power systems. As demands for higher power efficiency and density increase, achieving optimal design parameters becomes more challenging. Electromagnetic compatibility (EMC) and electromagnetic interference (EMI) compliance are usually an afterthought of design. However, modifying the converter circuit topology can reduce EMI, which in turn allows for smaller common-mode (CM) filters. This thesis builds upon previous research on the CLLC dc-dc converter (DCX) by presenting new experimental EMI measurements on three different DCX architectures operating at a higher switching frequency than the initial prototype. The results show that a fully balanced DCX reduces conducted CM EMI at the switching frequency and its harmonics, outperforming the benchmark and Navy Integrated Power Electronics Building Block topologies. Furthermore, a passive CM EMI filter was designed, constructed, and tested in accordance with military standards to mitigate conducted EMI across all topologies. The filter effectively reduces EMI and enables the CLLC DCX to meet CE102 limits across most of the frequency range, except for the fundamental frequency and the 9–10 MHz range.Distribution Statement A. Approved for public release: Distribution is unlimited.Major, United States Marine CorpsONR, Arlington, VA 2220
BLURRED BOUNDARIES: EXAMINING THE BOUNDARY BETWEEN AUTHORIZATIONS AND APPROPRIATIONS
No full textCongressional regulations delineate a distinction between defense authorization and appropriation bills, entrusting policy responsibilities to the Armed Services Committees and funding authority to the Appropriations Committees. However, overlapping jurisdictional boundaries often complicate this structure. This thesis explores whether the language used in legislation indicates jurisdictional overreach between these two committee systems. Employing a mixed-method approach, we conducted a Python-based keyword frequency analysis on the National Defense Authorization Acts and Defense Appropriations (NDAA) Bills from fiscal year (FY) 2020 through fiscal year 2024 to find instances of such overreach. This was followed by visual contextual verification and a third-party review to evaluate the frequency and type of provisions that are jurisdictionally non-conforming. The results revealed that FY2024 contained 15 instances of jurisdictionally non-conforming provisions out of 145 keyword occurrences, while the Appropriations Bill had 5 out of 96 indications of jurisdictionally non-conforming provisions. This suggests that authorizers may engage in jurisdictional overreach more frequently than appropriators. These findings challenge the conventional belief that fiscal committees are the primary source of overreach. The analysis demonstrates a method for analyzing congressional committee behavior.Distribution Statement A. Approved for public release: Distribution is unlimited.Lieutenant Commander, United States NavyLieutenant Commander, United States Nav
MOLECULAR DYNAMICS STUDY OF NEUTRON RADIATION DAMAGE ON ALUMINUM-GALLIUM NITRIDE
No full textThe displacement damage (DD) after a neutron scattering event is a key concern of materials exposed to neutron radiation environments. These scattering events were simulated in various compositions of AlGaN to investigate the relationship between Al composition and the residual DD using classical molecular dynamics (MD). Primary knock-on atoms (PKAs) of Al, Ga, and N were simulated at energies ranging from 250eV to 5keV in the Large-scale Atomic/Molecular Massively Parallel Simulator (LAMMPS) software suite. These PKAs were chosen randomly across each energy spectrum and AlGaN composition, with the number of interstitials and vacancies being recorded. Within LAMMPS, these displaced configurations were then put under a tensile test environment to determine the degradation of material strength. Results were such that a higher Al percentage composition was more sensitive to DD, with a Ga PKA producing the most damage. However, the decrease in the rigidity of each composition was nearly constant. Further test data is needed to validate these results, but this research adds to a foundation that could be expanded upon in the future with physical fabrication, irradiation, and assessment of bulk AlGaN and GaN-based high electron mobility transistors (HEMTs).Distribution Statement A. Approved for public release: Distribution is unlimited.Ensign, United States NavyGeneral Atomics NPS CRADA San Diego, CA 2910
HOW CAN NORSOF ENDURE ATTRITION ON SOF OPERATORS IN WARTIME?
Get PDFNorwegian Special Operation Forces (NORSOF) have time-consuming selection and training pipelines for their special operators. While the pipelines are suitable for operations where attrition is low, this thesis predicts that they are unable to sustain high attrition rates of special operators in war. By proposing three distinct courses of action (COA): 1) Make more NORSOF with the existing framework, 2) Make more NORSOF with a new framework, and 3) Get more out of NORSOF as it is, this thesis aims to provide NORSOF with a solution that ensures sustainability of special operators in war. The courses of action were analyzed through a sustainability, feasibility, and acceptability framework to determine their strengths and weaknesses. The analysis indicated that all three COAs have distinct qualities at different timesteps moving from peace to war. The current constructs of selection and training within NORSOF could be adapted to increase the production of special operators and be further enhanced with increased recruitment. Reserves present a viable, but limited capacity, while new formations could be a long-term solution for maintaining NORSOF’s utility in war. Preparing for all three COAs outlined in this thesis provides NORSOF commanders with redundancy when facing high attrition of special operators in war.Distribution Statement A. Approved for public release: Distribution is unlimited.Lieutenant Commander, Royal Norwegian Nav
Neutron Detection Using CNT-BNNT Resistive Detectors
Get PDFThis paper was presented at the 39th Annual HEART Conference Huntsville, AL, April 15–19, 2024.A Micro-Electro Mechanical Systems (MEMS)-based resistive sensor combining boron-nitride nanotubes (BNNTs) and multi-walled carbon nanotubes (MWCNTs) with an interdigitated electrode design, printed with conducting ink, can be used to detect thermal neutron radia tion. However, the sensitivities of these detectors have been shown to vary with the value of initial resistance. This work explores the reasons why the initial resistance of a BNNT and MWCNT mixture, forming percolative conductive paths between printed electrodes, influ ences the percent change in resistance of the sensor following thermal neutron exposure.In addition to explaining the reason for this dependence, the experiments conducted in this work attempt to determine an ideal initial resistance that produces the most sensitive neutron detector within an appropriate dynamic range
UNDERSTANDING THE EFFECTS OF AUTOMATED DECISION SUPPORT TOOLS ON NOVICE COGNITIVE WORKLOAD IN VR DAMAGE CONTROL SCENARIOS
No full textNovices in shipboard damage control environments face high cognitive demands with limited experience, often leading to critical decision errors. This thesis investigates whether automated decision support tools (DSTs) can reduce cognitive workload and improve task performance in novices within a virtual reality simulation. Thirty-three participants completed firefighting scenarios under four DST conditions (No DST, Auditory DST, Visual DST, Multimodal DST), and their cognitive workload and performance were measured through subjective ratings, physiological metrics (HRV, GSR), and performance. While MANOVA results showed a significant multivariate effect, univariate analyses revealed no significant differences in cognitive workload measures. However, performance scores were significantly higher in all DST-supported conditions, particularly in the auditory modality. The results suggest that while DSTs may not reduce perceived or physiological workload, they meaningfully enhance operational effectiveness. These findings indicate that novices were unaware of the additional cognitive demands imposed by the absence of DSTs, as neither the subjective nor the physiological indicators aligned with the performance decline. This thesis recommends that the Navy consider implementing auditory DSTs to support novices in visual search tasks and guide future development of decision aids attuned to the type of task. Implications, limitations, and directions for future research are discussed.Distribution Statement A. Approved for public release: Distribution is unlimited.Lieutenant Commander, Republic of Korea Nav