abstract: Readout Integrated Circuits(ROICs) are important components of infrared(IR) imag ing systems. Performance of ROICs affect the quality of images obtained from IR imaging systems. Contemporary infrared imaging applications demand ROICs that can support large dynamic range, high frame rate, high output data rate, at low cost, size and power. Some of these applications are military surveillance, remote sensing in space and earth science missions and medical diagnosis. This work focuses on developing a ROIC unit cell prototype for National Aeronautics and Space Ad ministration(NASA), Jet Propulsion Laboratory’s(JPL’s) space applications. These space applications also demand high sensitivity, longer integration times(large well capacity), wide operating temperature range, wide input current range and immunity to radiation events such as Single Event Latchup(SEL). This work proposes a digital ROIC(DROIC) unit cell prototype of 30ux30u size, to be used mainly with NASA JPL’s High Operating Temperature Barrier Infrared Detectors(HOT BIRDs). Current state of the art DROICs achieve a dynamic range of 16 bits using advanced 65-90nm CMOS processes which adds a lot of cost overhead. The DROIC pixel proposed in this work uses a low cost 180nm CMOS process and supports a dynamic range of 20 bits operating at a low frame rate of 100 frames per second(fps), and a dynamic range of 12 bits operating at a high frame rate of 5kfps. The total electron well capacity of this DROIC pixel is 1.27 billion electrons, enabling integration times as long as 10ms, to achieve better dynamic range. The DROIC unit cell uses an in-pixel 12-bit coarse ADC and an external 8-bit DAC based fine ADC. The proposed DROIC uses layout techniques that make it immune to radiation up to 300krad(Si) of total ionizing dose(TID) and single event latch-up(SEL). It also has a wide input current range from 10pA to 1uA and supports detectors operating from Short-wave infrared (SWIR) to longwave infrared (LWIR) regions. / Dissertation/Thesis / Masters Thesis Electrical Engineering 2019

The thesis compares two different methods for tracking and moving field lines. The first method included tracing one field line and moving each individual vertex along its own path with path following. The second method was done by tracing new field lines and using linear interpolation to move the field lines. The results show that the first method was incapable of rendering the field lines correctly due to the complexity and non-linearity of Earth's magnetic field. While it was successful at animating the initial motion of the field lines, it was not able to demonstrate the field line's change in topology. The second method was able to solve this issue, correctly visualizing field lines in motion, including changes in topology. However, the solution is limited in that it assumes that the vector field is static, which is not the case. To improve the visualization, a method for tracing and tracking field lines through multiple datasets is required. / <p>Examensarbetet är utfört vid Institutionen för teknik och naturvetenskap (ITN) vid Tekniska fakulteten, Linköpings universitet</p>

Hybrid energy systems are receiving more popularity in remote areas to provide low-cost electricity by taking advantage of existing electric generation systems and new generations of renewable energy resources. Such hybrid systems will increase reliability and decrease the cost of electricity. Renewable energy sources are gaining more attention due to their flexibility in utilization of locally available resources and their contribution in cleaner energy production. To this end, this thesis scrutinizes the viability of a hybrid renewable energy system (HRES) incorporating wind turbine and photovoltaic (PV) for Kagbeni village located in Nepal. The proposed framework covers both economic and technical aspects. For economic feasibility analysis, the Hybrid Optimization Model for Electric Renewables (HOMER) software is utilized to recognize the optimal size of required assets (i.e., PV module and wind turbine) to be incorporated into the current system. For the technical analysis, Electrical Transient Analyzer Program (ETAP) software is used to virtually model the projected HRES to assess the feasibility of the optimized HRES in operation modality (e.g., power flow, short circuit analysis, and protection coordination). The obtained results confirm that the integration of PV and wind units into the current Kagbeni power grid can lead to an economically feasible and reliable microgrid enhancing the social well-being of Kagbeni’s residents.

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The feasibility of relocating a small (~500,000 kg) Near-Earth Asteroid (NEA) to High Earth Orbit via Solar Electric Propulsion (SEP) is evaluated with the orbital simulation software General Mission Analysis Tool (GMAT). Using prior research as a basis for the mission parameters, a retrieval mission to NEA 2008 HU4 is simulated in two parts: approach from Earth and return of the Asteroid Redirect Vehicle (ARV) with the asteroid in tow. Success of such a mission would pave the way for future missions to larger NEAs and other deep space endeavors. It is shown that for a hypothetical launch time of 24 May 2016, the ARV could arrive within 25 km of 2008 HU4 on 28 Jun 2017 with a Delta V of 0.406 km/s, begin return maneuver on 08 Dec 2017 and reach Earth altitude of 450,000 km by 23 Apr 2026 with a Delta V of 44.639 m/s.

Electric propulsion systems utilize electrical energy to produce thrust for spacecraft propulsion. These systems have multiple applications ranging from Earth orbit North-South station keeping to solar system exploratory missions such as NASA’s Discovery, New Frontiers, and Flagship class missions that focus on exploring scientifically interesting targets. In an electromagnetic thruster, a magnetic field interacting with current in an ionized gas (plasma) accelerates the propellant to produce thrust. Pulsed inductive thrusters rely on an electrodeless discharge where both the magnetic field in the plasma and the plasma current are induced by a time-varying current in an external circuit. The multi-dimensional acceleration model for a pulsed inductive plasma thruster consists of a set of circuit equations describing the electrical behavior of the thruster coupled to a one-dimensional momentum equation that allow for estimating thruster performance. Current models lack a method to account for the time-varying energy distribution in an inductive plasma accelerator.

Modern radar and signal processing applications require data acquisition systems capable of high-speed analog data reception and processing. These systems need to support sophisticated signal processing algorithms and reliable high-speed interfaces. The objective of this project is to develop a prototype of a state of the art data acquisition system to aid NASA’s Surface Water and Ocean Topography (SWOT) mission. The SWOT mission aims at monitoring water levels of various water bodies to predict and avoid any catastrophic events. The principal instrument is a Ka-band Radar Interferometer (KaRIN) that is used for the measurement of water levels. The collected data need to be digitized and processed using an FPGA based-data acquisition system housed in a satellite. The scope of this project involves the design, implementation and test of a high-speed printed circuit board (PCB) that serves as the prototype data acquisition system. A lot of emphasis is placed on layout design, as the PCB needs to support data rates up to three Giga samples per second. The goal of this research is to provide Jet Propulsion Laboratory (JPL), NASA with a prototype version of the high- speed acquisition system that can be integrated with the KaRIN system in future.

When astronauts return from a space mission they smile for the cameras, but behind the scenes they undergo grueling rehab to recover from the effects of space and may face long-term health consequences. Space flights lasting more than thirty days are considered long-duration and may impact astronauts' long-term health due to space exposure; this requires the National Aeronautics and Space Administration to develop new scientific, medical, and space operational knowledge to counteract and mitigate harmful effects. Understanding how knowledge production occurs is an important analytical and policy issue at NASA. This dissertation explores knowledge production about astronaut health risks using structured and unstructured interviews conducted at Johnson Space Center, the home of mission control for NASA. Applied Actor-Network Theory using a stage analysis shows how various human and non-human actors create this knowledge, constructing, combining, and passing facts across disciplinary boundaries about health risks. A normative analysis of informant statements demonstrates how knowledge and values regarding their understanding of long-term astronaut health risks impact the actions and policies developed at NASA. Steven Hilgartner (1992) suggests that risk research has done very little examination of the social construction of risk objects. He further suggests (1992) that studies fail to systematically examine the construction of causal attribution networks that link chains of risk objects to harm. (Hilgartner, 1992, p. 40-41) This study remedies that lack concerning space medicine by filling in the intellectual, social, and institutional processes that link space flight characteristics to physical harms. / Doctor of Philosophy / Safe long-duration human spaceflight requires developing new scientific, medical, and space operations knowledge to counteract and mitigate space's harmful effects. NASA is preparing for a mission to the Moon between 2023 to 2025 and then to Mars by 2035. Both missions will test astronaut adaptability, endurance, and resilience. NASA will also test the impact on long-term astronaut health as latent effects may appear decades after completing long-duration missions. Mars is approximately eighty-five million miles away, and a mission to Mars will take approximately nine months. The astronauts will remain on Mars between thirty and a thousand days before returning to Earth. Astronauts will experience physiological and psychological changes testing their ability to survive exposure to the space environment. Safe long-duration human spaceflight requires new scientific knowledge due to the uncertain but potentially severe impacts on individual health. Therefore, understanding how knowledge production occurs is an important analytical and policy issue at the National Aeronautics and Space Administration. The question driving my research is how does NASA approach knowledge production, consumption, and enactment in the social construction of risk and concern regarding astronaut health, and are there flaws in NASA's approach that create barriers to knowledge production and the ethical treatment of astronauts? Given the daunting amount of scientific, medical, and epidemiological knowledge necessary to sustain human life and counteract the hazardous environment of space, NASA and commercial companies must decide if sustained missions to the Moon and Mars are possible.

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