Digital Commons Network^™

Bio-Inspired Flow Fields For Pem Fuel Cells- Decoupling Pressure And Distribution Effects On Performance And Identifying Design Opportunities, Joshua David Heck

Masters Theses

"The performance of Polymer Electrolyte Membrane Fuel Cells (PEMFCs) is significantly impacted by flow distributor geometry. The effects of flow distributor geometry on PEMFCs was explored in two ways in this study. Firstly, the relative effects of pressure and distribution characteristics of different flow fields on fuel cell unit and system level performance were considered. A method of decoupling these effects was proposed and demonstrated by application to the traditional serpentine and parallel flow field designs.The performance of these two designs were modeled computationally and it was shown that, of the 17% better performance of the serpentine design, 12% was …

Cfd Validation And Scaling Of Condensation Heat Transfer, Varun Kalra

Masters Theses

"A CFD study was performed using STAR-CCM+ to validate the software for its competence in the prediction and scaling of condensation heat transfer in the presence of air acting as a non-condensable gas. Three vertical concentric tube heat exchanger geometries with different diameters were studied in the CFD analysis. It was seen that the steam bulk temperatures predicted by STAR-CCM+ closely matched the experimental data. However, the temperatures of outer wall of the steel condenser tubes showed a deviation of 2% to 11% from the experimental values. The error in adiabatic water wall temperatures were found to range from 18% …

Analysis And Implementation Of Accident Tolerant Nuclear Fuels, Benjamin Joseph Prewitt

Masters Theses

"To improve the reliability and robustness of LWR, accident tolerant nuclear fuels and cladding materials are being developed to possibly replace the current UO₂/zirconium system. This research highlights UN and U₃Si₂, two of the most favorable accident tolerant fuels being developed. To evaluate the commercial feasiblilty of these fuels, two areas of research were conducted. Chemical fabrication routes for both fuels were investigated in detail, considering UO₂ and UF₆ as potential starting materials. Potential pathways for industrial scale fabrication using these methods were discussed.

Neutronic performance of 70%UN-30%U₃Si₂ composite …

Leveraging Knowledge At Startups, Amruta Anil Ranade

Masters Theses

"Startups contribute to the economy and job creation in the United States. One of the primary assets of startups is tacit knowledge of the employees of the startup. Technical communicators can help startups capture, share, and leverage the tacit knowledge at startups. Technical communicators could benefit from learning how knowledge management initiatives at startups work. The current study is an ethnographic case-study that was conducted at a fast-growing startup in California.

The data for the study was collected through observations, informal and semi-structured formal interviews with participants, and feedback from customers of the startup. The collected data was analyzed based …

Characterization Of The Rectification Behaviour Of In-Amps And Estimating The Near Field Coupling From Smps Circuits To A Nearby Antenna Using Dipole Moments, Chunyu Wu

Masters Theses

"This thesis discusses two parts.

In the first part, the rectification behavior of popular instrumentation amplifiers is measured in both common mode and single-ended RF noise injection. It is recommended that AD8221 be used in common mode RF noise injection environment. And AD8220 and AD8429 are recommended in single-ended RF noise injection environment. The mechanism of RF noise rectification inside in-amps is also discussed. It is verified that rectification mainly happens at the non-inverting input of two op-amps in the first stage of an in-amp. The DC voltage difference between inverting input and non-inverting input of the in-amp is further …

A Physics-Based Approach For Power Integrity In Multi-Layered Pcbs, Biyao Zhao

Masters Theses

"Developing a power distribution network (PDN) for ASICs and ICs to achieve the low-voltage ripple specifications for current digital designs is challenging with the high-speed and low-voltage ICs. Present methods are typically guided by best engineering practices for low impedance looking into the PDN from the IC. A pre-layout design methodology for power integrity in multi-layered PCB PDN geometry is proposed in the thesis. The PCB PDN geometry is segmented into four parts and every part is modelled using different methods based on the geometry details of the part. Physics-based circuit models are built for every part and the four …

Mining Asteroids For Volatile Resources: An Experimental Demonstration Of Extraction And Recovery, Egboche Christopher Unobe

Masters Theses

"Gaseous compounds trapped within carbonaceous asteroids may prove to be important targets for prospective space miners in the near-term. Volatile release is from hydrated, hydroxylated and carbonated phases present, making such bodies attractive as feedstock for the production of H₂O, CO₂ and simple organic compounds. A source of these species in orbit provides an opportunity to locally produce space-craft propellant and other life-support gases through the application of In-situ Resource Utilization (ISRU).

For this study, an experimental vacuum system was modified and used to test the technical validity of radiatively heating asteroid simulants to extract contained gaseous …

Effect Of Fracture Heterogeneity On Proppant Transport And Settling Mechanism, Dhurgham Abdulameer Kadhim

Masters Theses

"Proppant transport modeling through fractures with slickwater fluid systems assumes uniform and homogeneous fracture widths by implying constant fluid behavior at wall boundaries. Hydraulic fracturing mineback operations have demonstrated that induced fractures are heterogeneous and varying in width. This work investigates the impact of fracture width heterogeneity, roughness, and leak-off on ceramic proppant transport and settling, using proppant distribution concepts of Equilibrium Dune Level (EDL) and equilibrium Dune Length (EDX). Experimental work was conducted to investigate the impact of fracture width heterogeneity by varying fracture width along two plexiglass sheets. To mimic actual hydraulic fractures, the injection side was designed …

Detection Of Mine Roof Failure Using Inexpensive Lidar Technology, Ali Abdullah M. Alzahrani

Masters Theses

"Slope, Roof, and mine wall stability problems are some of the main reasons for deaths at U.S. surface or underground mining. The safety instruments were not enough to prevent that failure or even predict it before it occurs. However, the cost of such a tool that can be helpful in detecting roof failures is very high and not reachable in most instances.

The present study investigates the feasibility of using the M16 Leddar Evaluation Kit to detect the roof failure in mines. The M16 Leddar Evaluation kit cost is between 300$-800$, so it is the reachable price if it provides …

Quantifying Ceramic Proppant Transport In Complex Fracture Networks, Vivekvardhan Reddy Kesireddy

Masters Theses

"Water fracs have become an essential part of unconventional reservoirs to create deeper fracture networks. Proppant transport in water fracs is challenging in terms of fluids ability to carry the proppant deeper into these fracture networks. This experimental study investigates the impact of the flow rates, fracture widths and complexity controlling the ability of proppant to flow into complex fracture networks. This research attempts to nullify the knowledge gap in understanding width heterogeneity in primary and secondary fractures. This study speaks for settling pattern and proppant transport through a slot flow model with a unique approach to understand stage wise …

Trade Openness, Foreign Direct Investment And Infrastructure Spending: A Comparative Analysis Of Their Common Role In The Economic Development Between Selected Developed And Developing Economies, Yasser M. Alwafi

Masters Theses

This study examines the literature on how trade, foreign direct investments, and infrastructure development affect economic growth of selected developed and developing economies. A comparative analysis will be carried between developed economies (G7 countries) represented by Canada, France, Germany, Italy, Japan, the United Kingdom, and the United States while the developing economies (BRICS countries) are represented by Brazil, Russia, India, China and South Africa. The comparative analysis will be carried between years 1985 to 2015. In addition, the paper will establish the relationship between trade and economic growth in both developing and developed economies. Furthermore, the paper will establish that …

Determinants Of Import Demand In Ghana: 1960-2014, Freda Opoku-Agyemang

Masters Theses

This paper assesses the determinants of demand for import in Ghana using variables imports, exports, real gross domestic product, government spending, capital formation and exchange rate. The central aim of the study is to examine the relationship of Ghana's aggregate import demand and its determinants and then analyze the data from the period 1960 to 2014 and based on the above objectives, propose policies based on the results obtained from the analysis. All the data used were obtained from the World Bank database. The Johansen co-integration test suggested that there exists a long-run relationship between the imports (i.e. the dependent …

Gauging The Importance Of Microhabitat In Qualitative Macroinvertebrate Sampling In An Effluent Dominated Stream, Samuel James Gradle

Masters Theses

In the past different sampling strategies have been used to relate macroinvertebrate assemblages with habitat quality in the Sangamon River, above and below the sanitary district effluent discharge in Decatur, IL. The standard 20 jab method of proportional sampling in multiple microhabitats, based on QHEI physical habitat score, sampled allowed for comparison between sites based on overall community composition. However, it oversampled fine sediments, which dominate the Sangamon, therefore potentially missing sensitive taxa in isolated quality habitats. In the fall of 2016 I tested an enhanced qualitative approach to better gauge the importance of microhabitat types to macroinvertebrate assemblages in …

Survey And Data Analysis Of Weak Gel Treatments In Injection Wells, Zhuxing Chen

Masters Theses

"Excessive water production is a major concern in mature reservoirs. Weak gels have been applied in injection wells for in-depth profile modification. However, the data range and distribution of each parameter that affects performance of weak gels have not been studied thoroughly.

China has the largest amount of chemical-based conformance control treatments. This paper presents a summary of comprehensive data ranges and distributions for weak gel treatments based on the laboratory experiments and field applications in China from 2001 to 2010. The data set includes 76 cases compiled from China Academic Journals papers. In this study, reservoir properties, gel properties …

The Use Of Ceramic Water Filters Under Pressure In An In-Line Water Pumping System, Travis Dean Gardner

Masters Theses

"Ceramic pot filters (CPFs) have proven an effective point of use (POU) filter due to their relative low cost, ease to manufacture, and effectiveness at treating contaminated water. These filters are used by individual homes, and sometimes multiple filters are needed for each home in order to produce enough water for the family's household. If these filters could be used in-line with a pumping system or elevated storage tank, water could be filtered and used on demand for a community in an economically feasible way. However, CPFs are too fragile to use under pressure due to the weak points where …

Towards A Better Understanding Of Indoor Exposure To Air Pollutants: Window Opening Occurrence In U.S. Residences, Gauri Dilip Date

Masters Theses

"Opening a window dramatically alters how we are exposed to air pollutants. Online questionnaire surveys were deployed to assess window-opening occurrence of the occupants of US homes. This information will be used to better quantify population exposure to pollutants of indoor and outdoor origin. Frequency distributions of demographics were generated which showed percentages of respondents who participated in the surveys from categories including gender, race, household income and occupancy. In April 2016, 49.3% of the people surveyed opened their windows for at least 1 hour in a day. This increased to 52.5% in September 2016 and reduced considerably to 24.4% …

Cloth-Air Partitioning Of Oxybenzone, Jonathan T. Hill

Masters Theses

"Clothing has been proven to be a significant accumulator of chemicals from the air. Semi-volatile organic compounds (SVOCs) have a high affinity towards textiles, and measuring the equilibrium partition coefficient between cloth and air (K_cloth-air) for SVOCs is crucial in predicting human exposure to these compounds. This study aims to quantify K_cloth-air for oxybenzone to contribute to a larger human exposure experiment carried out at the Technical University of Denmark (DTU). K_cloth-air for oxybenzone was calculated using data collected from the exposure chamber at DTU and from performing extractions of oxybenzone in fabric samples from the …

Hydraulic Conductivity Testing Of Cement-Bentonite Mixes For Use In Annular Well Seals, Amy Lynn Norval

Masters Theses

"Grout is the material used in the annulus of water supply and monitoring wells to prevent movement of water from adjacent formations or from the land surface into the well. Grout is critical for preventing cross-contamination of aquifers through a borehole when a single well penetrates multiple aquifers and for protecting aquifers from surface contamination. The composition and emplacement of grout is regulated in most states, with standard mixes of bentonite and cement being the most widely used types of grout. Despite widespread adoption of grout regulations, surprisingly little literature is available to describe the effectiveness of different grout mixtures. …

Hydrogeochemical Controls On Reactive And Nonreactive Solute Transport In Heterogenous Porous Media, Mahta Gholizadeh Ansari

Masters Theses

"This work examines how physical and chemical heterogeneity can affect reactive and non-reactive transport in porous media. The effect of heterogeneity of the porous media is investigated both on dissolution rate of magnesite and attenuation time of nonreactive contaminants in non-reactive media. Various spatial distribution were created using statistical parameters in PETREL.A total of 6793 transport modeling simulations were run using CrunchFlow. Lasso regression was used to select most significant features and those features are then used in linear regression and deep learning models.

The magnesite dissolution simulations were performed under different permeability ratios (magnesite /sand permeability) and inlet pH. …

Processing, Microstructure, And Properties Of Engineered Diboride Structures, Connor Charles Wittmaier

Masters Theses

"The mechanical properties and processing parameters of boride ceramics in foam and laminate architectures were evaluated. The ceramic reticulated foam was produced through a polymer substrate replication technique and the hardness and compressive strength were tested. The laminate structure was tested to evaluate the flexure strength and work of fracture as a function of temperature.

The foam architecture was produced using a TiB₂ slurry coating on a polyurethane reticulated foam preform. Foams sintered to 2150⁰C displayed an average grain size of 8.9 ± 7.3 µm, and a hardness of 17.3 ± 2.4 GPa. Crush testing foams were sintered at …

Imaging In Karst Terrain Using The Electrical Resistivity And Multichannel Analyses Of Surface Wave Methods, Ragab W. Jaafar

Masters Theses

"Electrical resistivity tomography and multi-channel analyses of surface waves data were acquired at a study area in Phelps County in the south-central part of Missouri. The objectives of the investigation were fourfold: 1) to image the subsurface in the study area to a depth of 70 feet; 2) to compare the ERT images generated using both the dipole-dipole and Wenner-Schlumberger arrays; and 3) to assess how variations in the MASW array configuration affected MASW data quality; and 4) to compare the ERT-estimated depth to top-of-rock and the MASW-generated depth to top-of-rock.

The subsurface in the study area was imaged to …

Developing Restoration Schemes For A Road Transportation Network In The Event Of A Disaster, Ebin Antony

Masters Theses

"Transportation systems such as rail, road, and waterways are key component of critical infrastructure systems, providing connectivity between other components to enable the production and distribution of goods and services. During large scale disasters such as earth quakes and floods, this connectivity is disrupted, restricting or completely halting the flow of goods and services. To ensure that the connectivity between the different modes of transportation are restored in an aftermath of these disruptions, the interdependence between them and the importance of individual elements to the overall connectivity have to be studied and formulated to develop a system-level restoration plan. This …

Cyber-Physical Manufacturing Cloud: An Efficient Method Of Building Digital Twin For 3d Printer By Adapting Mtconnect Protocol, Liwen Hu

Masters Theses

"The common modeling of a virtual machine is using an information model to describe the physics of machines. The integration of digital twins into productive cyber-physical cloud manufacturing (CPCM) systems imposes strict requirements such as reducing overhead and saving resources for the systems. In this paper, we investigate a new method for building cloud-based digital twins (CBDT), which can be adapted to the CPCM platform. Our method helps reduce computing resources in the processing center and guarantees the fastest speed of the interactions between the human users and physical machines. We introduce a knowledge resource center (KRC) built on a …

Combination Of Bmp-2 And Relaxin To Induce Osteogenesis In Vivo, Sahitya Injamuri

Masters Theses

"Bone grafts are a common procedure for treating craniofacial injuries such as trauma, surgery, and reconstruction. Autografts and allografts have limitations which encourages the use of synthetic bone grafts. While synthetic bone grafts, such as hydroxyapatite (HA) microspheres, are advantageous for their cost and reproducibility, they lack the cells and growth factors needed for proper osteoinduction. Bone morphogenetic protein-2 (BMP-2) has been shown to increase the osteoinduction of grafts but the effective dose is above physiological levels and causes undesired effects on the body. Relaxin has been shown to enhance BMP-2's ability to induce bone formation in vitro and thus …

Well Log Interpretation And 3d Reservoir Property Modeling Of Maui-B Field, Taranaki Basin, New Zealand, Aziz Mennan

Masters Theses

"Maui-B is one of the largest hydrocarbon-producing fields in the Taranaki Basin. Many previous works have estimated reservoir volume. This study uses 3D property modeling, which is one of the most powerful tools to characterize lithology and reservoir fluids distribution through the field. This modeling will help in understanding the reservoir properties and enhancing the production by selecting the best location for future drilling candidates. In this study, 3D seismic, core, and well log data were used to build and define a structural model, facies analysis, and petrophysical parameters. After well log interpretation and petrophysical parameter calculations, each parameter was …

Unfinished: A Memoir, Bryan Edward Hebeler

Masters Theses

No abstract provided.

"In Motion", Mckenzie Dial

Masters Theses

No abstract provided.

Riemannian Reading: Using Manifolds To Calculate And Unfold Narrative, Heather Lamb

Masters Theses

The purpose of this study is to investigate the space where readers and texts interact. By applying non-Euclidean geometry to the modern subgenre of science fiction known as steampunk, we can see that narratives have no intrinsic geometry. Instead, what we can understand is that readers unflatten inherently flat narratives by applying their own metric of understanding to a narrative. Steampunk acts a primer to considering this mathematical process by explicitly flattening its settings and characters, as well as the historical accounts founding the narrative. Mark Hodder's novel, The Strange Affair of Spring-Heeled Jack, offers two characters that unsuccessfully …

Experimental And Numerical Study Of Dysphagia, Yash G. Potdar

Masters Theses

Dysphagia, meaning difficulty in swallowing, is a symptom of disease that occurs in young children and elderly people. It occurs particularly due to two reasons, weak neural network and/or deformities in oral section/s. The Helen DeVos Children’s Hospital’s Intensive Feeding Program takes care of children suffering from Dysphagia. In order to make the swallowing process easier and in some cases safer, thickener is added to the liquids. Depending on the requirement of thickness, the amount of thickener is varied. Although the directions to prepare the mixtures are given by the thickener product company, the required thickness is not achieved when …

Design And Realization Of A Nonlinear Vibration Energy Harvester For Cost Effective Additive Manufacturing, Rodrigo Barriuso De Juan

Masters Theses

Environmental energy harvesting has always been an attractive solution to the search for sustainable energy sources. Combined with the miniaturization and power consumption reduction of sensors and portable electronic devices, the possibility of powering using environmental energy, like vibration energy, instead of conventional batteries increases exponentially. Vibrational energy harvesting can be achieved using devices based on different physical phenomena. Electromagnetic based devices seem to be among the most effective when considering the power output levels within low frequency applications. However, these devices have always had inherent challenges including size and manufacturing cost reduction as well as limitations on the range …