Engineering Commons^™

Zirconium Diboride, Hexagonal Boron Nitride, And Amorphous Alumina Thin Films For High Temperature Applications, David Murdock Stewart

Electronic Theses and Dissertations

The use of microelectronic sensors and actuators in harsh, high temperature environments, such as power plants, turbine engines, and industrial manufacturing, could greatly improve the safety, reliability, and energy efficiency of these processes. The primary challenge in implementing this technology is the breakdown and degradation of thin films used in fabricating these devices when exposed to high temperatures >800 °C and oxidizing atmospheres. Zirconium diboride, hexagonal boron nitride, and amorphous alumina are candidate materials for use as thin film sensor components due to their high melting temperatures and stable phases. Zirconium diboride thin films have metallic-like electrical conductivity and remain …

Experimental Methods And Practices For The Study Of Toroidal Inflated, Braided Fabric Members, Daniel J. Whitney

Electronic Theses and Dissertations

Inflatable structures have become a very important area of interest for many differing applications where lightweight packable structures are required. NASA is developing Hypersonic Inflatable Aerodynamic Decelerator (HIAD) technology that takes advantage of stacked, inflated fabric tori to form a decelerating spacecraft nose cone. The tori consist of a bladder, braided fabric shell, and reinforcing in the form of integral cords or externally bonded straps. The focus of this thesis is on the development of methods for the structural testing of inflated fabric tori and developing an enhanced understanding of their behavior. This is essential for providing insight into the …

Microstructural Analysis Of Thermoelastic Response, Nonlinear Creep, And Pervasive Cracking In Heterogeneous Materials, Alden C. Cook

Electronic Theses and Dissertations

This dissertation is concerned with the development of robust numerical solution procedures for the generalized micromechanical analysis of linear and nonlinear constitutive behavior in heterogeneous materials. Although the methods developed are applicable in many engineering, geological, and materials science fields, three main areas are explored in this work. First, a numerical methodology is presented for the thermomechanical analysis of heterogeneous materials with a special focus on real polycrystalline microstructures obtained using electron backscatter diffraction techniques. Asymptotic expansion homogenization and finite element analysis are employed for micromechanical analysis of polycrystalline materials. Effective thermoelastic properties of polycrystalline materials are determined and compared …

A Multi-Channel 3d-Printed Bioreactor For Evaluation Of Growth And Production In The Microalga Dunaliella Sp, Cristian A. Cox

Electronic Theses and Dissertations

We explored the capabilities of additive manufacturing using a photo-cured jetted material 3D printer to manufacture a milli-microfluidic device with direct application in microalgae Dunaliella sp growth and intracellular compounds biosynthesis tests. A continuous microbioreactor for microalgae culture was CAD designed and successfully built in 1 hour and 49 minutes using black photopolymer cured by UV and a support material. The microreactor was made up of 2 parts including the bioreactor itself and a microchannel network for culture media fluids and microalgae. Both parts were assembled to form a single unit. Additional optical and auxiliar components were added. An external …

Identification Of Critical Locations And Reduced Model State Estimation For Power System Analysis, Amamihe Onwuachumba

Electronic Theses and Dissertations

In order to reduce the carbon footprint and the cost of electric energy, the owners of electric power utilities today are faced with the task of reducing the use of expensive and carbon intensive fossil fuels and significantly increasing the amount of energy from renewable sources in their grids while meeting an increase in electricity demand. To deal with increase in demand, electric utilities operate very close to their maximum capacities and this sometimes results in violating security limits. Therefore, the integration of intermittent renewable energy into the utility grids poses serious concerns that must be addressed to ensure grid …

Analysis And Recommendations To Improve Traffic Safety & Flow For Pedestrians Bicyclists And Motorists Along Franklin Street, Matthew Pelletier

Electronic Theses and Dissertations

Franklin Street is a minor arterial servicing Portland, Maine that connects Commercial Street and Route 1 to I-295 and has been a target for redevelopment for some time. Franklin is the epitome of traffic congestion, and has unsafe conditions for pedestrians, bicyclists and motorists alike. Portland is the biggest city in Maine and is an important hub for employment, housing and tourism throughout the year. As the city grows, there is a greater demand to build more sustainable, multi-use streets to service all modes of transportation that supports business development, open space and growth. This new vision is being applied …

Development Of Eco-Friendly Composite Foam Boards For Thermal Insulation And Packaging Purposes Using Cellulose Nanofibrils (Cnf), Nadir Yildirim

Electronic Theses and Dissertations

Reducing energy consumption is a high priority in the United States and throughout the world. Energy used to heat and cool occupied constructed facilities is of particular concern, and one of the most effective strategies is insulating the building envelope. Historically, builders used whatever material was available to fill the void between interior and exterior walls, including wool fibers, paper, and even corn cobs. Today, homes are built using foam insulation that harden when applied, blown-in loose insulation, fiberglass mats or rigid foam boards usually composed of polystyrene. Rigid foam boards are used in a variety of applications despite the …

Production Of Acetic Acid In Kraft Pulp Mill Biorefinery Using Bi-Polar Membrane Electrodialysis, Ravikant Amogisidha Patil

Electronic Theses and Dissertations

The objective of this dissertation was to develop a process for the production of acetic acid in kraft mills. Acetyl groups in hardwood can be hydrolyzed using alkali at 50 °C. The product from this process contains about 15 g/L of sodium acetate and was determined to be suitable for the production of acetic acid.

Experiments performed using aqueous sodium acetate to evaluate the ability of electrodialysis (ED) to separate and concentrate sodium acetate showed that sodium acetate can be concentrated up to 275 g/L starting with an initial concentration of 17 g/L. The transport of water with sodium and …

Integrating Laminated Strand Lumber And Lumber From Northeastern U.S. Forests Into Cross-Laminated Timber, Nicholas Matthew Willey

Electronic Theses and Dissertations

The objective of this research was to conduct a technical assessment of the engineering properties of cross-laminated timber (CLT) made from local Northeastern lumber, laminated strand lumber (LSL) and mixtures of the two. The technical assessment provided the bending and shear strength and stiffnesses values for select CLT configurations, which were used to determine the feasibility of using local Northeastern lumber and LSL in CLT. Experimental lay-up designs were created for six three-layer CLT configurations using Spruce-Pine-Fir (South) (SPFs) No.2 and better and 1.35E LSL. Preliminary shear block tests were run to determine the optimal spread rate, and a board …

Improvement Of Soil Spring Model For The Analysis Of Buried Arch Structures, Leo N. Helderman

Electronic Theses and Dissertations

The University of Maine has developed concrete filled fiber-reinforced polymer (FRP) tubes (CFFTs) for use in bridge construction. A finite element model was previously developed to analyze these buried arch structures during construction, service live load, and ultimate load. Two shortcomings in that model include how the load distribution method and the soil reaction due to construction and service loads are modeled. There were two objectives to this research: to make a user-friendly software package to analyze a variety of buried arch structures and to improve the existing model to better predict the soil-structure interaction. Prototype software was developed complete …

Modeling And Measurement Of Evaporation From Frequently Tilled Sandy Soils, Nicholas R. Lawson

Electronic Theses and Dissertations

Moisture observation and control is the single largest factor that controls the mechanical properties of sand based surfaces used for thoroughbred horse racing. Currently the moisture content is estimated based on the experience and expertise of the superintendent and water is added as needed based on experience. While extensive modelling has been done on moisture loss from a range of soils with crop covers in agronomy, currently no method exists to estimate the evaporation from a surface that is tilled many times a day and remains in a partially compacted state. This thesis develops an evaporation model based on real …

Characterization Of A Wind Tunnel For Use In Offshore Wind Turbine Development With Mitigation Measures For The Wall Effect Of Proximal Structures, James Newton

Electronic Theses and Dissertations

This thesis supports the development of the Harold Alfond W² Ocean Engineering Laboratory constructed at the University of Maine through several investigations conducted with a one-third scale wind generation system. The scale wind generator is first tested in what is considered an open-circuit wind tunnel configuration to determine the influence proximal building walls of a facility housing such a device may have on the consistency and capacity of a wind generator. Turbine performance testing with the wind generator to identify any susceptibility to proximal wall influence is also conducted. This is of interest as the full-scale system will operate …

Impact Of Wind Generation On Dynamic Voltage Characteristics Of Power Systems, Luis Badesa

Electronic Theses and Dissertations

In recent times there has been an increasing interest in renewable energies due to public awareness of the negative effects on the environment of conventional electricity generation resources like coal and oil, and several policies have been enacted requiring progressive reduction of fossil-fuel-based generation. Due to some favorable characteristics of wind over other renewables, wind power has grown considerably in the last two decades.

Integration of wind generation into the existing power grids poses significant challenges. The limited reactive power capability that wind turbines have can cause several problems, such as important voltage drops or rises in the system. Therefore, …