A worldwide shift from fossil fuels to zero carbon energy sources is imperative to limit global warming to 1.5°C. While integrating high penetrations of VRE into the grid may introduce the need for upgrading an aging electrical system, renewable energy represents a new opportunity to decarbonize multiple sectors. Otherwise curtailed solar and wind energy can accelerate deep decarbonization in hard-to-reach sectors - transportation, industrial, residential, and commercial buildings, all of which must be decarbonized to limit global warming. With renewable energy as its input, electrolytic H₂ represents a solution to the supply-demand mismatch created by the proliferation of VREs on a grid designed for on-demand power. Electrolytic H₂ can stabilize the grid since the H2 created can be stored and transferred. Thus, Chapter 1 introduces the opportunity of green H2 in the context of low-cost VREs as a means of deep decarbonization through sector coupling, and an overview of the techno-economics, key technologies, and life cycle assessment versus the incumbent steam methane reformation. The growing imbalances between electricity demand and supply from VREs create increasingly large swings in electricity prices. Capable of operating with variable input power and high current densities without prohibitively large ohmic losses, polymer electrolyte membrane (PEM) electrolyzers are well suited to VREs. In Chapter 2, polymer electrolyte membrane (PEM) electrolyzers are shown to help buffer against these supply demand imbalances, while simultaneously minimizing the levelized cost of hydrogen (LCOH) by ramping up production of H2 through high-current-density operation when low-cost electricity is abundant, and ramping down current density to operate efficiently when electricity prices are high. A techno-economic model is introduced that optimizes current density profiles for dynamically operated electrolyzers, while accounting for the potential of increased degradation rates, to minimize LCOH for any given time-of-use (TOU) electricity pricing. This model is used to predict LCOH from different methods of operating a PEM electrolyzer for historical and projected electricity prices in California and Texas, which were chosen due to their high penetration of VREs. Results reveal that dynamic operation could enable reductions in LCOH ranging from 2% to 63% for historical 2020 pricing and 1% to 53% for projected 2030 pricing. Moreover, high-current-density operation above 2.5 A cm−2 is shown to be increasingly justified at electricity prices below $0.03 kWh−1. These findings suggest an actionable means of lowering LCOH and guide PEM electrolyzer development toward devices that can operate efficiently at a range of current densities. Chapter 3 uses techno-economic modeling to analyze the benefits of producing green (zero carbon) hydrogen through dynamically operated PEM electrolyzers connected to off-grid VREs. Dynamic electrolyzer operation is considered for current densities between 0 to 6 A cm-2 and compared to operating a PEM electrolyzer at a constant current density of 2 A cm-2. The analysis was carried out for different combinations of VRE to electrolysis (VRE:E) capacity ratios and compositions of wind and solar electricity in 4 locations – Ludlow, California, Dalhart, Texas, Calvin, North Dakota, and Maple Falls, Washington. For optimal VRE:E and wind:PV capacity ratios, dynamic operation of the PEM electrolyzer was found to reduce the LCOH by 5% to 9%, while increasing H₂ production by 134% to 173%, and decreasing excess (i.e. curtailed) electrical power by 82% to 95% compared to constant current density operation. Under dynamic electrolyzer operation, the minimum LCOH is achieved at higher VRE:E capacity ratios than constant current density operation and a VRE mix that was more skewed to whichever VRE source with the higher capacity factor at a given location. In addition, dynamically operated electrolyzers are found to achieve LCOH values within 10% of the minimum LCOH over a significantly wider range of VRE:E capacity ratios and VRE mixes than constant electrolyzers. As demonstrated, the techno-economic framework described herein may be used to determine the optimal VRE:E capacity and VRE mix for dynamically-operated green hydrogen systems that minimize cost and maximize the amount of H2 produced. Chapter 4 focuses on the production of high-purity water and H₂ from seawater. Current electrolyzers require deionized water so they need to be coupled with desalination units. This study shows that such coupling is cost-effective in H₂ generation, and offers benefits to thermal desalination, which can utilize waste heat from electrolysis. Furthermore, it is shown that such coupling can be optimized when electrolyzers operate at high current density, using low-cost solar and/or wind electricity, as such operation increases both H₂ production and heat generation. Results of techno-economic modeling of PEM electrolyzers define thresholds of electricity pricing, current density, and operating temperature that make clean electrolytic hydrogen cost-competitive with H₂ from steam methane reforming. By using 2020 hourly electricity pricing in California and Texas, H₂ is shown to be produced from seawater in coupled desalination-electrolyzer systems at prices near $2, reaching cost parity with SMR-produced H₂. Chapter 5 concludes the dissertation with an overview of the challenges and research needs for PEM electrolyzers at scale, including projected iridium needs, iridium thrifting, recycling methods, key degradation mechanisms, a failure modes and effects analysis, and LCOH projections.

Ransomware has been a growing threat to today's organizations, with irreparable damages and billions of dollars lost, it is crucial for organizations to implement mitigation strategies that can counter these attacks. With phishing attempts being the primary attack vector, it is evident that organizations need to implement the best practices in order to avoid the consequences. Thus, this study addresses the question “How do the actual ransomware mitigation strategies implemented by Swedish organizations compare to the best practices suggested in literature, with a focus on phishing emails as a common means of ransomware transmission?” The study was conducted by utilizing semi-structured interviews and interviewing five participants that work or have worked as IT-security consultants which are then summarized and analyzed with a thematic analysis approach. Seven relevant themes and fifteen sub-themes were introduced and analyzed in order to answer the proposed research question: attack vector, security awareness training, technical solutions, challenges of solutions, frameworks, evolution and keeping yourself updated. All participants were contacted via Linkedin and the interviews were done virtually via Zoom. The findings of this study shows that Swedish organizations utilize a minimal amount of ransomware mitigation strategies due to the lack of resources, care and overall awareness regarding the topic. According to the interviewed participants, basic forms of technical solutions and administrative solutions are mostly implemented, however they are a lacking form of medium and can generally be bypassed easily. The primary factors that were brought up and introduced was security awareness training and technical solutions. Essentially, it all boils down to employee’s incompetence and lack of security awareness. No matter how many technical solutions that are implemented within an organization, if an employee is not aware that they shouldn’t click on malicious links, an infection might spread.

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The implementation of Nationally Determined Contributions (NDC) in 2020 has coincided with the outbreak of COVID-19. Recovery paths taken to deal with the economic consequences of the pandemic can be either an opportunity to foster a sustainable growth or a return to business-as-usual model. Assuming that national budgets define the economic strategy of governments, this thesis addresses the relationship between mitigation pledges outlined in NDCs and mitigation-related expenditure in Chile, Peru and Colombia pre- and during the COVID-19 pandemic. A deductive thematic analysis of NDCs is used to identify the prioritized mitigation sectors and to allow for a refined focus in the analysis of the relevant mitigation-related expenses for each case country. Budgets of 2020 and 2021 are compared and discussed in the light of previous research. Results show different levels of climate ambition but common prioritised sectors (energy, land-use, and industry). Regarding Peru, the budgets indicate a higher mitigation ambition than their NDC by including expenditure in areas that are not mentioned in the NDC. Contrary, Colombia and Chile have detailed NDCs that cover more aspects than indicated through their government expenditure. Generally, energy and industry expenditure misalign with the NDC pledges, due to the increase of expenses on national fossil fuels resources in 2021. Land-use mitigation expenditure, linked to forestry and agriculture, have increased in Chile and Peru but are hardly represented in Colombia. Thus, the thesis outlines early misalignments of mitigation targets with government expenditure and differences in accountability and transparency that could challenge the monitoring of progress towards the achievement of the pledges.

In 1852, a five-minute long earthquake hit the Banda Arc region that was felt over most of Indonesia. It caused uplift of new islands and sent a tsunami across the Banda Sea that reached a height of 8 meters at Banda Neira and was also registered at Ambon, Saparua and other islands. Records of the 1852 earthquake at multiple locations provide the constraints needed to reconstruct the disastrous event through earthquake intensity analysis and numerical modeling of the tsunami. Using tsunami heights and arrival times as the major constraints, best fit numerical models of the tsunami were constructed using Clawpack. These models indicate that the earthquake was most likely a mega-thrust event along the Tanimbar Trough with a Mw of around 8.4. At least 10-15 meters of elastic strain energy has accumulated along the Tanimbar Through since the 1852 event, and the population in the region has increased exponentially. When another event occurs ≥ that in 1852, there will be many more people and treasure in harms way.

Radio astronomy synthesis imaging arrays are composed of many parabolic reflector antennas. These antennas are designed to be extremely sensitive to detect faint emissions from astronomical sources. Unfortunately, this also makes them susceptible to radio frequency interference (RFI) from man made sources such as orbiting satellites. The radio astronomy research group at Brigham Young University (BYU) is investigating methods to mitigate the effects of RFI in radio astronomy synthesis imaging. Though real-time RFI mitigation has been demonstrated for a large single dish telescope, for synthesis imaging arrays our prior work has consisted solely of algorithm development and computer simulations. To test our algorithms on experimental data we need an image synthesis array at BYU. The primary contribution of this Master's thesis is the design and construction of a working image synthesis array on the roof of the Clyde Building at BYU. This thesis describes the design of the antenna placement for the synthesis array. Antenna placement is the primary factor for determining image quality since the placement dictates the shape of the synthesized beam. Simulations were performed, prior to the array's construction, to predict the quality of images from the array. Another contribution of this thesis is signal processing code to generate correlations of the signals from the antennas. Code was written to calibrate measured data and generate an image from the correlations. Code was also written to steer the antennas and track astronomical phenomena. The performance of the array is evaluated in this thesis. The culmination of this thesis is a radio image of the supernova remnant Cassiopeia A. This thesis concludes with simulations of an RFI mitigation experiment that can be performed with the new array (pending certain improvements to the array).

Radio frequency interference (RFI) is a growing problem for radio astronomers. One potential solution utilizes spatial filtering by placing an array of electrically small antennas at the focal plane of a parabolic reflector. This thesis documents the design and characterization of a prototype array feed and RF receiver that were used to demonstrate the spatial filtering principle. The array consists of a 7-element hexagonal arrangement of thickened dipole antennas tuned to a center frequency of 1600 MHz. The receiver is a two-stage, low-noise frequency mixer that is tunable over the entire L-band. This thesis also documents a new receiver design that is part of an upgrade to the outdoor antenna test range for the National Radio Astronomy Observatory in Green Bank, West Virginia. The array feed was demonstrated on a three-meter parabolic reflector by recovering a weak signal of interest that was obscured by a strong, broadband interferer. Similar results were also obtained when the interferer moved with an angular velocity of 0.1 degree per second, but only when the power in the interferer dominated the signal. The aperture efficiency was measured at 64%, but adaptive beamformers can slightly perturb this value through distortions in the beam pattern. This phenomenon, called pattern rumble, effectively reduced the sensitivity of the radio telescope, and was measured by comparing the SNRs of adaptive beamformers to the SNR of a fixed-weight beamformer. It was found that pattern rumble can reduce the useful integration time by roughly one order of magnitude. It was also found that mechanical instability of the primary reflector introduces a great deal of pattern rumble, even when the interferer is fixed in direction.

Radio astronomy is the discipline dedicated to the study of celestial emissions in the radio band from a few MHz to 300 GHz. In recent years, spurious emissions from man-made devices that operate at these frequencies have made detection of astronomical signals difficult. These harmful RF transmissions are called radio frequency interference (RFI). One strategy to remove RFI is to apply spatial filtering using an array antenna. This thesis documents the development of a high-speed data acquisition system used to record data from 7- and 19-element phased array feeds. The system supports synchronous sampling over all channels and streams data to disk allowing spatial filtering to be applied in post-processing. The development of a time blanking RFI mitigation system was also developed as part of this thesis. Time blanking is a strategy to remove radar interference by blanking the time intervals corrupted by radar transmissions. The two blanking strategies are time window blanking and detected pulse blanking. This thesis documents the design and implementation of a detected pulse blanking system built using FPGAs. The system employs complex signal processing techniques to detect and excise radar transmissions in real time. This FPGA RFI mitigation system is the first to use a matched filter in pulse detection. Successful radio frequency interference mitigation is demonstrated by removing simulated radar interference from a sinusoidal tone.

This work presents on-orbit experiments conducted to validate SEU mitigation and detection techniques on FPGA devices and to measure SEU rates in FPGAs and SDRAM. These experiments were designed for the Cibola Flight Experiment Satellite (CFESat), which is an operational technology pathfinder satellite built around 9 Xilinx Virtex FPGAs and developed at Los Alamos National Laboratory. The on-orbit validation experiments described in this work have operated for over four thousand FPGA device days and have validated a variety of SEU mitigation and detection techniques including triple modular redundancy, duplication with compare, reduced precision redundancy, and SDRAM and FPGA block memory scrubbing. Regional SEU rates and the change in CFE's SEU rate over time show the measurable, expected effects of the South Atlantic Anomaly and the cycle of solar activity on CFE's SEU rates. The results of the on-orbit experiments developed for this work demonstrate that FPGA devices can be used to provide reliable, high-performance processing to space applications when proper SEU mitigation strategies are applied to the designs implemented on the FPGAs.

As the cost of variable renewable energy resources like wind and solar decline rapidly the major barrier to decarbonization of the electrical grid becomes that of energy storage. Current storage technologies are much too expensive to justify widespread adoption and it is unclear what type of technology is even capable of fulfilling this role. Flow batteries are an often proposed technological solution to this problem but they are plagued by high cost and reliability issues due to the expensive and complex balance of plant included in the system design. In this work a new design for a gravity driven flow battery is explored which is capable of drastically lowering the cost of flow batteries by removing the pumps and membranes and replacing their function with density stratification and flow driven by the density change of the electrode reactions. A design for a zinc-bromine battery which makes use of this free convection during operation is explored. The system is studied through construction of prototype cells, exploration of key design variables, and a techno-economic analysis of the technology is performed showing cost viability. The free convection phenomenon which underlies the battery operation is expanded upon by connecting non-dimensional correlations in heat transfer with electrochemical transport equations in order to create predictive understanding of flow behavior based on system composition. This correlative understanding is used to construct a model of a zinc-bromine gravity driven flow battery. This model shows results which align with experimental data and gives insight into the complex transport dynamics of the system.