
Pratt, Rose Marie
by Rose Marie Pratt.

Long, Michael J. (Michael Joseph)
This thesis proposes a low size, weight, and power (SWaP) laser communication pointing, acquisition, and tracking (PAT) design for CubeSats in low earth orbit (LEO). As data production onorbit continues to grow due to sensor miniaturization and the increased prevalence of satellites in LEO, current RF communication systems struggle to meet the data routing demands on resource constrained platforms. Laser communication provides an attractive alternative with reduced regulatory constraints and efficient use of available SWaP, but introduces the new challenge of stringent pointing requirements. The approach in this thesis is to survey historic capable laser communication space systems and identify...

Couchman, Benjamin Luke Streatfield
The ability to handle discontinuities appropriately is essential when solving nonlinear hyperbolic partial differential equations (PDEs). Discrete solutions to the PDE must converge to weak solutions in order for the discontinuity propagation speed to be correct. As shown by the LaxWendroff theorem, one method to guarantee that convergence, if it occurs, will be to a weak solution is to use a discretely conservative scheme. However, discrete conservation is not a strict requirement for convergence to a weak solution. This suggests a hierarchy of discretizations, where discretely conservative schemes are a subset of the larger class of methods that converge to...

Deyo, Matthew Quinn
Driving is often stressful and dangerous due to uncertainty in the actions of nearby vehicles. Having the ability to model driving maneuvers qualitatively and guarantee safety bounds in uncertain traffic scenarios are two steps towards building trust in vehicle autonomy. In this thesis, we present an approach to the problem of Qualitative Autonomous Driving (QAD) using riskbounded conditional planning. First, we present Incremental Riskaware AO* (iRAO*), an online conditional planning algorithm that builds off of RAO* for use in larger dynamic systems like driving. An illustrative example is included to better explain the behavior and performance of the algorithm. Second,...

Liu, Katherine Y
While measurement covariances are often taken to be constant in many robotic state estimation systems, many sensors exhibit different interactions with their environment. Accurate covariance estimation allows graphbased estimation techniques to better optimize state estimates by reasoning about the utility of different methods relative to each other. This thesis describes a method of learning compact feature representations for realtime covariance estimation. A direct loglikelihood optimization technique is used to train a deep convolutional neural network to predict the covariance matrix of a Gaussian measurement model, given representative data. This method is algorithmagnostic, and therefore does not require the handcoding of...

Atsaves, Louis
Sicklecell diseased persons suffer finite pain episodes (luring their lifetime, which are termed sickle cell crises. Using a sickle cell blood flow model, we mathematically demonstrate that the onset of a sickle cell crisis is chaotic. We further show that sickle cell crises may be mitigated by manipulating certain physiological parameters, namely the partial pressure of oxygen at 50% hemoglobin ([mathematical formula]%) and the kinetic dissociation rate of hemoglobin (kub) These physiological parameters control the chaotic nature of sickle cell crises and have the ability to transfer a person from a crisis state to a noncrisis state. We determine that...

Öztürk, Berk
Geometric programs (GPs) and other forms of convex optimization have recently experienced a resurgence due to the advent of polynomialtime solution algorithms and improvements in computing. Observing the need for fast and stable methods for multidisciplinary design optimization (MDO), previous work has shown that geometric programming can be a powerful framework for MDO by leveraging the mathematical guarantees and speed of convex optimization. However, there are barriers to the implementation of optimization in design. In this work, we formalize how the formulation of nonlinear design problems as GPs facilitates design process. Using the principles of pressure and boundedness, we demonstrate...

Duncan, Robert C. (Robert Clifton)
by Robert C. Duncan.

Chilton, Robert G; Seville, Alfred R
by Robert G. Chilton and Alfred R. Seville.

Bain, John B; Michaelis, Frederick H; Wootton, James C
by John B. Bain, Frederick H. Michaelis, James C. Wootton.

Hennick, Cooper Curtis
Electroaerodynamic (EAD) propulsion is a form of inatmosphere electric thrust generation with no direct emissions, no moving parts, and is nearly silent. Previous work has quantified the thrusttopower and thrust density of EAD propulsion. An unmanned aerial vehicle (UAV) was designed with the optimization tool GPkit and with the flight mission goal of steadylevel flight. This thesis describes the design and testing of several subsystems of the UAV, including the power system, the communication system, the aircraft tail, and the aircraft launching system. The power system is tested to deliver up to a maximum of 600 W at 40 kV....

Gibson, Alison Eve
The future of human space exploration will involve extravehicular activities (EVA) on foreign planetary surfaces (i.e. Mars), an activity that will have significantly different characteristics than exploration scenarios on Earth. These activities become challenging due to restricted vision and limitations placed on sensory feedback from altered gravity and the space suit. The use of a bulky, pressurized EVA suit perceptually disconnects human explorers from the hostile environment, increasing navigation workload and risk of collision associated with traversing through unfamiliar terrain. Due to the hazardous nature of this work, there is a critical need to design interfaces for optimizing task performance...

Frey, Kristoffer M. (Kristoffer Martin)
The navigation problem for mobile robots operating in unknown environments can be posed as a subset of Simultaneous Localization and Mapping (SLAM). For computationallyconstrained systems, maintaining and promoting system sparsity is key to achieving the highrate solutions required for agile trajectory tracking. This thesis focuses on the computation involved in the elimination step of optimization, showing it to be a function of the corresponding graph structure. This observation directly motivates the search for measurement selection techniques to promote sparse structure and reduce computation. While many sophisticated selection techniques exist in the literature, relatively little attention has been paid to the...

Ayton, Benjamin James
Exploration of new environments is often conducted in search of some phenomenon of interest. Examples include the search for extreme forms of life in the deep ocean or under the ice on Europa, or localizing resource deposits on the ocean floor. Exploration of all these environments is dangerous because of uncertainty in the environment and poorly characterized disturbances that can damage the exploration vehicle. Autonomous vehicles allows exploration in those environments where it is too dangerous or expensive to send a humanoperated craft. Autonomous exploration has been wellstudied from the perspective of information maximization, but information gathering has not been...

Lowey, Charlotte (Charlotte Emily)
Penetrator probes emplace by impact into a solid medium, carrying scientific instrumentation to fulfil specified postimpact mission objectives. They have been used successfully for multiple terrestrial applications, but only flown once unsuccessfully as a planetary exploration vehicle, with many proposed penetrator missions over several decades being cancelled at various stages of development. We examine past applications of penetrator probes alongside current Antarctic research instrumentation, setting out the context for design and analysis work carried out on the Geodetic Seismic Ice Penetrator (GSIP). GSIP is a separable twobody penetrator designed for airdeployment from LC130 aircraft into snow pack on the Ross...

Hoskin, Dominique (Dominique Sampson)
An improved doublet panel method for calculating the aerodynamic properties of lifting surfaces in supersonic flows is derived and implemented. The lifting surfaces are discretized into an arbitrary number of doublet panels with unknown singularity strength, whose perturbation velocity potentials satisfy the supersonic PrandtlGlauert equation. To prevent field singularities in the potential and velocity, the doublet strength of each panel is piecewise linear and continuous in the streamwise direction. In addition, the panels can be swept at different angles at their leading and trailing edges, allowing for generalized lifting surfaces to be analyzed. The component of the perturbation velocity that...

Brooks, Callen T. (Callen Theodore)
The implementation of Performance Based Navigation (PBN) routes across the National Airspace System (NAS) has caused a significant concentration of flight tracks. This flight track concentration also creates a concentration of noise impacts on the communities surrounding airports, which has led to an increase in noise complaints at many airports that have implemented these routes. In order to understand these changes in noise, and to design procedures that could help mitigate any negative effects, it is important to have modeling tools capable of capturing the noise impacts of flight track variability. This thesis develops a model for this purpose. First,...

Vernacchia, Matthew T
Small, unmanned aerial vehicles (UAVs) are expanding the capabilities of aircraft systems. However, a gap exists in the size and capability of aircraft: no aircraft smaller than 10 kilograms are capable of flight faster than 100 meters per second. A small, fast aircraft requires a propulsion system which is both miniature and highpower, requirements which current UAV propulsion technologies do not meet. To meet this need, a slowburning solid rocket motor has been developed. Such motors require slowburning solid propellants with tailorable burn rate. This thesis reports experimental results and combustion theory for a slowburning solid propellant. It also describes...

Good, Marissa Ann
Launch vehicle hardware is traditionally very expensive to design, develop, produce and certify, because it must operate in extreme environments with high reliability. The result is that most hardware for NASAfunded launch vehicles is custom built to execute a specific mission on a single platform. In contrast to other industries (e.g. automotive), very few components are used across product platforms, a strategy known as reuse that has the potential to decrease the cost, schedule and risk of new product introduction. Budget constraints on NASA's next launch vehicle, the Space Launch System (SLS), brought about a desire to realize some of...

Zuo, Heng (Heng Elizabeth)
Slumping (or thermal shaping) of thin glass sheets onto high precision mandrels was used by NASA Goddard Space Flight Center to fabricate the NuSTAR telescope with success. But this process requires long thermal cycles and produces midrange spatial frequency errors due to the antistick mandrel coatings. Over the last few years, MIT Space Nanotechnology Lab has developed a noncontact slumping process differentiating from the preceding contact slumping, which utilizes a pair of porous air bearing mandrels through which compressed nitrogen is forced, with a thin piece of glass sheet floating between two thin layers of nitrogen during the thermal cycle....