Scholarship & Research
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Item RadPC@Scale: an approach to mitigate single event upsets in the memory of space computers(Montana State University - Bozeman, College of Engineering, 2022) Williams, Justin Patrick; Chairperson, Graduate Committee: Brock LaMeresThis thesis presents the flight test results of a single event upset (SEU) mitigation strategy for computer data memory. This memory fault mitigation strategy is part of a larger effort to build a radiation tolerant computing system using commercial-off-the-shelf (COTS) field programmable gate arrays (FPGAs) called RadPC. While previous iterations of RadPC used FPGA block RAM (BRAM) for its data memory, the specific component of RadPC that is presented in this paper is a novel external memory scheme with accompanying systems that can detect, and correct faults that occur in the proposed data memory of the computer while allowing the computer to continue foreground operation. A prototype implementation of this memory protection scheme was flown on a Raven Aerostar Thunderhead high-altitude balloon system in July of 2021. This flight carried the experiment to an altitude of 75,000 feet for 50 hours allowing the memory in the experiment to be bombarded with ionizing radiation without being attenuated by the majority of Earth's atmosphere. This thesis discusses the details of the fault mitigation strategy, the design-of-experiments for the flight demonstration, and the results from the flight data. This thesis may be of interest to engineers that are designing flight computer systems that will be exposed to ionizing radiation and are looking for a lower cost SEU mitigation strategy compared to existing radiation- hardened solutions.Item Optimization of error correcting codes in FPGA fabric onboard cube satellites(Montana State University - Bozeman, College of Engineering, 2019) Tamke, Skylar Anthony; Chairperson, Graduate Committee: Brock LaMeresThe harmful effects of radiation on electronics in space is a difficult problem for the aerospace industry. Radiation can cause faults in electronics systems like memory corruption or logic flips. One possible solution to combat these effects is to use FPGAs with radiation mitigation techniques. The following Masters of Science thesis details the design and testing of a radiation tolerant computing system at MSU. The computer is implemented on a field programmable gate array (FPGA), the reconfigurable nature of FPGAs allows for novel fault mitigation techniques on commercial devices. Some common fault mitigation techniques involve triple modular redundancy, memory scrubbing, and error correction codes which when paired with the partial reconfiguration. Our radiation tolerant computer has been in development for over a decade at MSU and is continuously being developed to expand its radiation mitigation techniques. This thesis will discuss the benefits of adding error correcting codes to the ever developing radiation tolerant computing system. Error correcting codes have been around since the late 1940's when Richard Hamming decided that the Bell computers he did his work on could automate their own error correcting capabilities. Since then a variety of error correcting codes have been developed for use in different situations. This thesis will cover several popular error correcting method for RF communication and look at using them in memory in our radiation tolerant computing system.Item Kinetic modeling of gold nanoparticle formation for radiation dose prediction(Montana State University - Bozeman, College of Engineering, 2017) Akar, Burak; Chairperson, Graduate Committee: Jeff Heys; James Wilking (co-chair)Nanoparticles have numerous uses in the biomedical sciences, and this study focused on use of gold nanoparticles (GNPs) for measuring ionizing radiation dose. GNPs synthesized at various radiation doses were experimentally characterized and two mathematical models were developed to simulate the synthesis process. The first is based on the Finke-Watzky model and predicts the rate of soluble gold salt conversion to GNPs, and the second model is based on a population balance model and predicts nanoparticle concentration and size distribution. The model parameters that provided an optimal fit to experimentally gathered data were determined, and both models were able to capture the experimental absorbance time trends. The population balance model, however, had the greater predictive power as it was able to capture mean particle size trends that were consistent with experimental measurement.Item A radiation tolerant computer mission to the International Space Station(Montana State University - Bozeman, College of Engineering, 2017) Julien, Connor Russell; Chairperson, Graduate Committee: Brock LaMeresThe harmful effects of radiation on electronics used in space poses a difficult problem for the aerospace industry. Memory corruption and other faults caused by the harsh radiation environment are difficult to mitigate. The following Masters of Science thesis describes the design and testing of a radiation tolerant, low-cost computer system to meet the increasing demand of fault tolerant space computing. The computer is implemented on a modern Field Programmable Gate Array (FPGA), which enables a novel fault mitigation strategy to be deployed on a commercial part, thus reducing the cost of the system. Using modern processing nodes as small as 28nm, FPGAs can provide increased computational performance and power efficiency. Common mitigation techniques like triple modular redundancy and memory scrubbing are expanded by utilizing partial reconfiguration on the FPGA and by introducing extra spare processors. Our computer system has been in development at Montana State University for the past 10 years and has undergone a series of technology demonstrations to increase its technical readiness level. These include high energy particle bombardment at the Texas A&M Radiation Effects Facility, 8 high altitude balloon flights to 30km, and two sounding rocket flights to altitudes greater than 120km. This computer is currently being demonstrated onboard the International Space Station and will be the payload for two stand-alone small satellite missions in low Earth orbit in 2018. This Masters of Science thesis presents improvements to the system by moving the design to a new, low power FPGA with a new processor synchronization method. This thesis will present the design, testing, and characterization of the computer system along with conveying data collected by the experiment on the International Space Station.Item Infrared cloud imaging systems characterization(Montana State University - Bozeman, College of Engineering, 2016) Riesland, David Walter; Chairperson, Graduate Committee: Joseph A. ShawInfrared cloud imaging (ICI) is a useful tool for characterizing cloud cover for a variety of fields. Clouds play an important role in free-space high frequency (optical and mm-wave) terrestrial communications. Ground-based infrared imagers are used to provide long-term, high resolution (spatial and temporal) cloud data without the need for sunlight. This thesis describes the development and characterization of two ICI systems for deployment at remote field sites in support of Earth-to-space mm-wave and optical communication experiments. The hardware upgrades, calibration process, sensitivity analysis, system validation, and algorithm developments are all discussed for these systems. Relative spectral response sensitivity analysis is discussed in detail, showing as much as 35% calibrated scene radiance uncertainties when using generic manufacturer data in comparison with measured spectral responses. Cloud discrimination algorithms, as well as cloud phase (ice or water discrimination) algorithms are also discussed.Item A microstructural investigation of radiation recrystallized snow layers(Montana State University - Bozeman, College of Engineering, 2016) Walters, David John; Chairperson, Graduate Committee: Edward E. AdamsRadiation recrystallized snow is a pervasive weak layer of snow that, once buried, increases the threat of snow avalanches. While much is known about the conditions required to form radiation recrystallized snow layers, little is understood about the microstructural intricacies that develop resulting in decreased macro-scale mechanical stability. This study utilizes the Subzero Science and Engineering Research Facility at Montana State University to recreate clear daytime meteorological conditions to induce near surface metamorphism in snow. This metamorphic process develops radiation recrystallized layers of faceted crystals in the top 1-2 cm of snow over the course of 12 hours. Mechanical testing is performed before and after recrystallization to compute the relative change in mechanical properties of the recrystallized snow sample. Near surface samples are also extracted and imaged at regular intervals using computed tomography. Imaging results in a 3-D reconstruction of representative snow microstructures recording the temporal evolution of faceted crystal formation. The microstructural data is utilized in two modeling approaches which seek to describe the macro-scale mechanical properties of the snow. A previously developed homogenization approach, which computes macro-scale effective stiffness properties using micromechanical interactions and texture, is enhanced by incorporating measures of individual grain shapes and differing textural measures. Another approach leverages the microstructure directly by simulating the response of macro-scale loads on a geometric mesh of the imaged microstructure using finite element methods. Following recrystallization, physical mechanical testing demonstrated that the metamorphism process forms a stiff and strong sublayer capped by a weaker layer of faceted snow that is 75-80% less stiff in shear and 80-90% less stiff in compression than the strong layer below it. Microstructural analysis revealed multiple fine layers of unique crystal morphologies existing within the faceted region. Homogenization reflected reasonable trends in relative changes of effective stiffness properties but suffered from volumetric scale problems when analyzing the faceted layer. Finite element methods also reasonably computed the relative change in macro-scale effective properties as a result of changes to the microstructural geometry. Additionally, the finite element method estimates changes to effective strength and the location of mechanical failure within the faceted layers.Item Implementation of a radiation-tolerant computer based on a LEON3 architecture(Montana State University - Bozeman, College of Engineering, 2015) Turner, David Lee Douglas; Chairperson, Graduate Committee: Brock LaMeresIt is desired to create an inexpensive, open-source, radiation-tolerant computer for space applications using commercial, off-the-shelf parts and a proven space-grade processor. Building upon previous work to develop the triplicate architecture using MicroBlaze soft-processors, this implementation, using a modification of the popular open-source space-grade LEON3 soft processor from Cobham Gaisler, enables more compatibility with NASA and existing space computing resources. A partially reconfigurable, triple modular redundant LEON3 processor was successfully implemented in a four-core design on an Artix-7 Field Programmable Gate Array to demonstrate an inexpensive and open-source method of developing radiation-hardened-by-architecture computer systems.Item An experimental test of semiclassical radiation theories(Montana State University - Bozeman, College of Letters & Science, 1972) Wessner, John MiltonItem An examination of constitutive direct light DNA repair and inducibility of DNA repair in two thermophilic bacteria(Montana State University - Bozeman, College of Letters & Science, 1985) Kirkpatrick, Mary Ann StarkeyItem Differential recovery of antibody responses to various antigens after sublethal whole-body irradiation(Montana State University - Bozeman, College of Agriculture, 1981) Newman, Edward Lee