The most common railroad accidents today involve collisions between trains and passenger vehicles at railroad grade crossings [1][2]. Due to the size and speed of a train, these collisions generally result in significant damage and serious injury. Despite recent efforts by projects such as Operation Lifesaver to install safety features at grade crossings, up to 80% of the United States railroad grade crossings are classified as 'unprotected' with no lights, warnings, or crossing gates [2]. Further, from January to September 2012, nearly 10% of all reported vehicle accidents were a result of train-to-vehicle collisions. These collisions also accounted for nearly 95% of all reported fatalities from vehicular accidents [2]. To help provide a more rapidly deployable safety system, advanced dedicated short range communication (DSRC) systems are being developed. DSRC is an emerging technology that is currently being explored by the automotive safety industry for vehicle-to-vehicle (V2V) and vehicle-to-infrastructure (V2I) communications to provide intelligent transportation services (ITS). DSRC uses WAVE protocols and the IEEE 1609 standards. Among the many features of DSRC systems is the ability to sense and then provide an early warning of a potential collision [6]. One potential adaption for this technology is for use as a train-to-vehicle collision warning system for unprotected grade crossings. These new protocols pose an interesting opportunity for enhancing cybersecurity since terrorists will undoubtedly eventually identify these types of mass disasters as targets of opportunity. To provide a thorough channel model of the train to vehicle communication environment that is proposed above, large-scale path loss and small scale fading will both be analyzed to characterize the propagation environment. Measurements were collected at TTCI in Pueblo Colorado to measure the received signal strength in a train to vehicle communication environment. From the received signal strength, different channel models can be developed to characterize the communication environment. Documented metrics include large scale path loss, Rician small scale fading, Delay spread, and Doppler spread. An analysis of the DSRC performance based on Packet Error Rate is also included. / Master of Science

Natural disasters damage infrastructure and create significant obstacles to humanitarian aid efforts. Roads may become unusable, hindering or halting efforts to provide food, water, shelter, and life-saving emergency care. Finding a safe route during a disaster is especially difficult because as the disaster unfolds, the usability of roads and other infrastructure can change quickly, rendering most navigation services useless. With the proliferation of cheap cameras and unmanned aerial vehicles [UAVs], the rapid collection of aerial data after a natural disaster has become increasingly common. This data can be used to quickly appraise the damage to critical infrastructure, which can help solve navigational and logistical problems that may arise after the disaster. This work focuses on a framework in which a UAV is paired with an unmanned ground vehicle [UGV]. The UAV follows the UGV with a downward-facing camera and helps the ground vehicle navigate the flooded environment. This work makes several contributions: a simulation environment is created to allow for automated data collection in hypothetical disaster scenarios. The simulation environment uses real-world satellite and elevation data to emulate natural disasters such as floods. The environment partially simulates the dynamics of the UAV and UGV, allowing agents to ex- plore during hypothetical disasters. Several semantic image segmentation models are tested for efficacy in identifying obstacles and creating cost maps for navigation within the environ- ment, as seen by the UAV. A deep homography model incorporates temporal relations across video frames to stitch cost maps together. A weighted version of a navigation algorithm is presented to plan a path through the environment. The synthesis of these modules leads to a novel framework wherein a UAV may guide a UGV safely through a disaster area. / Master of Science / Damage to infrastructure after a natural disaster can make navigation a major challenge. Imagine a hurricane has hit someone's house; they are hurt and need to go to the hospital. Using a traditional GPS navigation system or even their memory may not work as many roads could be impassible. However, if the GPS could be quickly updated as to which roads were not flooded, it could still be used to navigate and avoid hazards. While the system presented is designed to work with a self-driving vehicle, it could easily be extended to give directions to a human. The goal of this work is to provide a system that could be used as a replacement for a GPS based on aerial photography. The advantage of this system is that flooded or damaged infrastructure can be identified and avoided in real-time. The system could even identify other possible routes by using photography, such as driving across a field to reach higher ground. Like a GPS, the system works automatically, tracking a user's position and sug- gesting turns, aiding navigation. A contribution of this work is a simulation of the environment designed in a video game engine. The game engine creates a video game world that can be flooded and used to test the new navigation system. The video game environment is used to train an artificial intel- ligence computer model to identify hazards and create routes that would avoid them. The system could be used in a real-world disaster following training in a video game world.

Underwater gliders are robust and long endurance ocean sampling platforms that are increasingly being deployed in coastal regions. This new environment is characterized by shallow waters and significant currents that can challenge the mobility of these efficient (but traditionally slow moving) vehicles. This dissertation aims to improve the performance of shallow water underwater gliders through path planning. The path planning problem is formulated for a dynamic particle (or "kinematic car") model. The objective is to identify the path which satisfies specified boundary conditions and minimizes a particular cost. Several cost functions are considered. The problem is addressed using optimal control theory. The length scales of interest for path planning are within a few turn radii. First, an approach is developed for planning minimum-time paths, for a fixed speed glider, that are sub-optimal but are guaranteed to be feasible in the presence of unknown time-varying currents. Next the minimum-time problem for a glider with speed controls, that may vary between the stall speed and the maximum speed, is solved. Last, optimal paths that minimize change in depth (equivalently, maximize range) are investigated. Recognizing that path planning alone cannot overcome all of the challenges associated with significant currents and shallow waters, the design of a novel underwater glider with improved capabilities is explored. A glider with a pneumatic buoyancy engine (allowing large, rapid buoyancy changes) and a cylindrical moving mass mechanism (generating large pitch and roll moments) is designed, manufactured, and tested to demonstrate potential improvements in speed and maneuverability. / Ph. D.

through the act of separation architecture is born This thesis is a study of separation, asking the question of whether the act of separation can elevate the composition of material, space, and light to awaken the mind, eye, and soul. The vehicle for this study is an artisans' retreat placed on the ridge line of Brush Mountain located in Blacksburg, Virginia. This project explores the idea of separation and the moments it creates at many scales: man to nature, maker to made, public to private, structure to skin, and detail to whole. This project consists of two lines. One houses the makers and one supports the place for the making, consisting of studio spaces for sculpting, painting, and creating ceramics. Lastly, this project contains two other structures for the public to partake in the celebration of the creations: an outdoor amphitheater and a gallery which displays current and past work of resident artists. / Master of Architecture

Where are the boundaries between past and present, dream and reality, private and public, action and perception? Upon these opposites, we journey through our lives. If the purpose of architecture is more than the construction of a shelter, then architecture also is a reflection of these contradictions in a human mind. The goal of this project is to illustrate how the notion of life's journey is similar to the experience of theatre, and how the architecture of the theatre can answer the questions above. / Master of Architecture

In the current literature, split path gear trains are analyzed for use in helicopter transmissions and marine gearboxes. The goal in these systems is to equalize the torque in each path as much as possible. There are other gear trains where the operator intends to hold the torque split unevenly. This allows for control over the gearbox bearing loading which in turn has a direct effect on bearing stiffness and damping characteristics. Having control over these characteristics is a benefit to a designer or operator concerned with suppressing machine vibration. This thesis presents an analytical method for analyzing the torque in split path gear trains. A computer program was developed that computes the bearing loads in various gearbox arrangements using the torque information gathered by the analytical method. A case study is presented that demonstrates the significance of the analytical method in troubleshooting an industrial gearbox that has excessive vibration. / Master of Science

Let K be a field and Q a finite directed multi-graph. In this paper I classify all path algebras KQ and admissible orders with the property that all of their finitely generated ideals have finite Groebner bases. / Master of Science

Time is an ever-present entity that is an incredibly complex yet constant force in the life of each and every one of us. Since earliest history, humanity has attempted to recognize and use the evaluation of time to an advantage, eventually developing time into measurable commodity with determinable value. Beyond the obvious respect of time measurement, the larger concept of 'time' and its applications is of value to nearly every discipline. In the case of architecture, we have the ability to manipulate and use time to serve a purpose, whether that be creating a sundial to celebrate time passing or creating a black box to shield us from time's presence. In most cases though, time is merely a variable to work with to achieve a higher goal. This thesis looks to reverse this concept and use time and its varying manifestations as the main parameter to drive and develop architecture. In this case, the architecture will take the form of a school; a perfect example of a program in need of the recognition of time not only for its fluctuating yet ordered schedules and calendars, but also for the conservation and expedient use of this valuable commodity. Most importantly though, a school provides a significant opportunity to showcase the educational capability that results from the experience in, and the observance of, time itself. This thesis will produce a design for a Pre-K-through-8th grade school to be located on the site of the existing Jefferson-Houston School in Alexandria, VA. / Master of Architecture

This thesis is a proposal for a large contemporary art museum on the Presidio Parade Grounds in San Francisco, California. The site is small and historic, thus my solution was to build primarily underground. Through my exploration of designing a subterranean art museum I addressed the challenges of natural lighting, circulation, and curation. The following images document the result of my studies. / Master of Architecture

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