The goal of this project is to design a roadway in Tucson, Arizona, that extends from the existing Sabino Canyon Road south to connect to Kolb Road over the Vincent Mullins Landfill and across Pantano Wash. The roadway would ease traffic conditions at this site, which exceed design capacity during morning and evening peak hours. The project encompasses transportation, hydrological, structural and geotechnical design, and an environmental assessment. The team followed City of Tucson design codes and regulations, load and resistance factor design, and American Association of State Highway and Transportation Officials bridge design manuals during the design process. Different load combinations were used to design the 43-foot bridge deck span, which includes four traffic lanes, two pedestrian pathways, and parapet walls for safety. The team chose a slab design for its constructability. Based on soil types and soil borings, a geotechnical support structure was designed to elevate the span above the Vincent Mullins Landfill. A full hydrological analysis was conducted to evaluate the runoff from a neighboring park into an existing culvert, as well as drainage from the roadway. The Hydrologic Engineering Center’s River Analysis System, or HEC-RAS, developed for the U.S. Army Corps of Engineers, was used to determine if channel improvements were necessary to convey stormwater runoff from the roadway and park to Pantano Wash. Environmental permitting and stormwater pollution prevention plan were completed to satisfy City of Tucson codes.

Macadamia nuts are a valuable cash crop in Hawaii. Commercial harvesting requires at least three types of heavy machinery, each with a single specialized function. The project’s purpose is to design and prototype a single robotic nut-harvesting vehicle to replace the multiple machines currently used, facilitating faster harvesting and eliminating the cost of harvesting by hand. The robotic machine must be able to navigate a macadamia nut orchard with minimum human interaction for the nine-month harvesting season. The objective is to increase crop yield from conventional small-scale harvesting methods, and to provide a consistent harvesting schedule for Kawainui Farm. The vehicle platform was designed to accommodate a hopper in which to collect nuts, electrical components for power and navigation, and a pickup head to collect nuts on the ground. The vehicle relies on GPS and computer vision to navigate a preprogrammed path through the orchard. Hawaii’s heavy rainfall limits GPS use, so the vehicle can be manually radio controlled.

Contamination of food and water by E. coli is a major global health problem. Although most strains are harmless, some are pathogenic and can cause food poisoning, severe infection, and death. The goal of this project is to design a system to optically detect E. coli in real time, with a focus on developing a device to read paper microfluidic chips, which are a low-cost, biodegradable sensing platform. Antibody-conjugated particles placed on a paper chip bind when exposed to E. coli, resulting in a change in optical signal caused by particle-size-dependent scattering. Current detection methods require smartphone processing and computational software, and are prone to error and false readings caused by inconsistent ambient lighting. The process was made more precise by creating a device that reads red, green and blue values of scattered light in a closed casing produced by 3-D printing. Using an Arduino microcontroller instead of a smartphone and desktop software reduces cost and makes the sensor more feasible for use in developing nations. The device could be adapted to detect other bacteria.

While satisfying nutritional needs, mushroom cultivation is financially sustainable and can supplement carbon dioxide required by plants in a crop-production system. The goal of this project is to design and build an efficient and cost-effective mushroom growth chamber as part of a larger system of crop production. The mushroom-growing system design consists of storage shelves, fruiting chambers, a laminar flow hood, and a humidity control system. The design includes a cabinet to convert the laminar flow hood to an inoculation station and a humidifier with microcontroller-based sensor control. The layout of the fruiting chambers and walking areas meet safety requirements and were designed in cooperation with the plant production and irrigation infrastructure teams (Teams 15090 and 15091). Through controlled environment practices, the mushroom growing system will deliver a nutritionally dense product to offset food insecurity, and provide an opportunity for further research.

The purpose of this project is to design and install an irrigation system for a greenhouse built inside a shipping container. This system needs to provide sufficient quantity and quality of water to plants in a nutrient film technique system and in deep-flow hydroponics trays. A closed, self-sustaining system, with an ultraviolet filter on its exit pipes, was designed to allow reuse of irrigation water. The team chose a one-tank design to save space and water. When the deep flow hydroponics trays are filling, no water is running through the nutrient film technique system. When the trays are full, the pump switches to circulating water through the nutrient film technique system. Shelf and outlet height are adjustable to accommodate different plants, which are fertilized by depositing nutrients directly into the water. A water outlet is provided for humidifiers.

The rise of food deserts, areas in which affordable and nutritious food is hard to find, prompted this project to design and build a compact and efficient hydroponic system housed within a shipping container that can be transported to such areas. The constrained area of the shipping container led to a design using two high-density growth hydroponic systems covering 200 square feet, in which Butterhead lettuce was grown in deep flow and nutrient film technique systems. Development of specifications and design of the lighting, nutrient, and growth system was based on research by the agricultural and biosystems engineering department and consultation with engineering experts. This mobile engineered system gives food desert communities the power to end the drought.

Potting protects electronics components from shock, vibration, and moisture by encapsulating them in substances like epoxies, silicones and urethanes, but vacuum impregnation is superior because it removes air and allows the potting material to fill micropores and channels. The goal of this project is to design a vacuum impregnation system that protects capacitors against corrosion by water. The system consists of a vacuum chamber connected to a sealed rotary vane pump. Capacitors and a range of potting agents are placed under vacuum at -15 inches of mercury, which degasses them, and the capacitors are coated with potting material. Vacuum is released and reapplied several times to ensure that voids in the capacitors are degassed and filled with potting material. Potted components are cured in an oven and kept in a humidity chamber for a week at 100 percent humidity and 90 degrees Celsius. Capacitance is monitored during this period; changes in capacitance are directly correlated to water corrosion in the capacitors.

Vehicles powered by hydrogen fuel cells store hydrogen as a cooled liquid at 20 degrees kelvin or a compressed gas at 10,000 pounds per square inch. An alternative that eliminates the need for these extremes of temperature and pressure is to heat a compound containing covalently bonded hydrogen, causing it to release the hydrogen to the fuel cell. Ammonia borane, which is stable at ambient conditions, requires minimal energy for dehydrogenation, and is rich in hydrogen, is a possible storage medium for hydrogen. If a viable storage system could be engineered, demand for ammonia borane as a source of hydrogen would increase. The goal of this project is to develop a processing plant and to optimize design specifications for scaling up processing of ammonia borane through the metathesis reaction pathway. Optimization of individual unit operations was determined using quality-by-design concepts, which allowed the team to confirm scalability, design limitations, and competitive market pricing. The final design involves the application of two mixers, two reactors, and four separators. The plant design should yield 99 percent pure ammonia borane.

The objective of this project was to design a chemical plant that uses cultivated algae, a sustainable energy source, grown on-site to produce carbon-neutral biofuel. The design includes a supercritical carbon dioxide extractor for the triglycerides in the algae cells, base-catalyzed transesterification in continuously stirred reactors in series, and final separation processes to produce a high-grade biofuel. The environmental considerations of the design include using carbon dioxide for algae growth and the solid-extraction process, and using methanol for the transesterification and liquid extraction, which made recycling easy and further reduced the fuel’s environmental footprint.

The goal of this project is to design a modification enabling a plant that produces ethanol for E85 fuel to switch production to spirits such as whiskey. The Pinal Energy ethanol plant in Maricopa, Arizona, was used as a basis for modeling ethanol production. The design uses a new and proprietary technology that pumps ethanol through flavor additives such as oak chips, using a packed-bed reactor, to age whiskey about 120 times faster than standard barrel aging. During normal ethanol production, denaturant is added in the final step to avoid alcohol taxation. The modified plant design removes this last step and includes piping to the new whiskey-aging vessels. The whiskey produced would be roughly 80-120 proof. Other byproducts that could be sold are carbon dioxide and dried distiller’s grain. The plant would be modified for two months of the year for whiskey production. Ethanol would be produced for eight months, with two months set aside for the plant to change processes. The ethanol plant produces 50 million gallons of ethanol per year. The modified plant would produce approximately 33 million gallons per year of ethanol and 16 million gallons per year of whiskey.