Engineering Commons^™

Asynchronous Data Processing Platforms For Energy Efficiency, Performance, And Scalability, Liang Men

Graduate Theses and Dissertations

The global technology revolution is changing the integrated circuit industry from the one driven by performance to the one driven by energy, scalability and more-balanced design goals. Without clock-related issues, asynchronous circuits enable further design tradeoffs and in operation adaptive adjustments for energy efficiency. This dissertation work presents the design methodology of the asynchronous circuit using NULL Convention Logic (NCL) and multi-threshold CMOS techniques for energy efficiency and throughput optimization in digital signal processing circuits. Parallel homogeneous and heterogeneous platforms implementing adaptive dynamic voltage scaling (DVS) based on the observation of system fullness and workload prediction are developed for balanced …

Design And Analysis Of An Asynchronous Microcontroller, Michael Hinds

Graduate Theses and Dissertations

This dissertation presents the design of the most complex MTNCL circuit to date. A fully functional MTNCL MSP430 microcontroller is designed and benchmarked against an open source synchronous MSP430. The designs are compared in terms of area, active energy, and leakage energy. Techniques to reduce MTNCL pipeline activity and improve MTNCL register file area and power consumption are introduced. The results show the MTNCL design to have superior leakage power characteristics. The area and active energy comparisons highlight the need for better MTNCL logic synthesis techniques.

Trend Analysis Of Water Quality In Northwest Arkansas Streams Reflects Changes In The Watershed, Zachary Paul Simpson

Graduate Theses and Dissertations

Watershed export of nutrients, sediments, and chemicals impacts receiving waters. Changes within the watershed (e.g., anthropogenic or climatic) can alter the transport of constituents in streams. Stream monitoring is crucial for understanding these effects. This study developed a potential improvement to flow-adjusting constituent concentrations in streams, an important step of analyzing monitoring data in lotic systems for trends. The method incorporates a K-fold cross-validation procedure to optimize a model explaining the relationship between the concentration and streamflow, thus providing a valuable tool to researchers in water quality. Additionally, two case studies were conducted on watersheds located in northwest Arkansas using …

Evaluating A Measure-Calculate Method For Determining Sediment Oxygen Demand In Lakes, Adrian Beirise

Graduate Theses and Dissertations

A steady-state mass diffusion model used with simple measurable and calculable inputs for determining sediment oxygen demand (SOD) is compared to an intact core incubation (ICI) SOD method using samples from three lakes. The mass diffusion model coupled with inputs is known as the measure-calculate method (M-C) and is a potential alternative to existing methods for measuring SOD which are more complex, time-consuming, and costly. The M-C method requires inputs for volumetric sediment oxygen uptake (Ṅsed), sediment density and porosity, and water properties. Ṅsed was determined by suspending sediment in oxygen-saturated water with a DO probe and determining the steady …

Study Of Plasmonic Properties Of The Gold Nanorods In The Visible To Near Infrared Light Regime, Pijush Kanti Ghosh

Graduate Theses and Dissertations

Nanostructures of noble metals show unique plasmonic behavior in the visible to near-infrared light range. Gold nanostructures exhibit a particularly strong plasmonic response for these wavelengths of light. In this study we have investigated optical enhancement and absorption of gold nanorods with different thickness using finite element method simulations. This study reports on the resonance wavelength of the sharp-corner and round-corner rectangles of constant length 100 nm and width 60 nm. The result shows that resonance wavelength depends on the polarization of the incident light; there also exists a strong dependence of the optical enhancement and absorption on the thickness …

Electrodeionization Versus Electrodialysis: A Clean-Up Of Produced Water In Hydraulic Fracturing, Brigitte Marie Rodgers

Graduate Theses and Dissertations

Electrodeionization (EDI) is a widely studied process ranging from applications in wastewater clean-up in the food and beverage industry to purifying organic compounds. To date, there are no apparent studies on applying this technology to produced wastewater recovered from hydraulic fracking sites. Water consumption within hydraulic fracturing sites can reach in the upwards of millions of gallons per site, so a need for a water recycling process becomes necessary within areas where water requirements are scarce. Implementation of an EDI module that is capable of handling high salt solutions from produced wastewater in subsequent fracturing practices will decrease overall water …

Initial Structural Subsidence As Reflected In Morrowan And Atokan (Pennsylvanian) Subsurface Stratigraphy, Northern Arkoma Basin, North-Central Arkansas, Fatimah Taher Nahi Al Asadi

Graduate Theses and Dissertations

The Arkoma Basin is a carboniferous foreland basin that is known for its prolific gas production. The objective of this research is to study the initial subsidence of the basin by analyzing the strati-graphic and structural features of the study area. This was accomplished through IHS Petra, Surf-er 13, and Win-Tensor software. Field work studies comprised a large part of this study. Also, a seismic profile and Google earth elevation profiles are among the methods used to study the initial subsidence of the Arkoma Basin. The study area within the basin represents a transitional zone from the shelf into the …

Modeling Economic Impacts Of The Inland Waterway Transportation System, Furkan Oztanriseven

Graduate Theses and Dissertations

The inland waterway transportation system of the United States (U.S.) handles 11.7 billion tons of freight annually and connects the heartland of the U.S. with the rest of the world by providing a fuel-efficient and environmentally friendly mode of transportation. This dissertation aims to create decision support tools for maritime stakeholders to measure the economic impacts of the inland waterway transportation systems under real world scenarios including disruptions, demand changes, port expansion decisions, and channel deepening investments. Monte Carlo simulation, system dynamics, discrete-event simulation, agent-based modeling, and multiregional input-output modeling techniques are utilized to analyze the complex relationships between inland …

Channel Estimation Overhead Reduction For Downlink Fdd Massive Mimo Systems, Abderrahmane Mayouche

Graduate Theses and Dissertations

Massive multiple-input multiple-output (MIMO) is the concept of deploying a very large number of antennas at the base stations (BS) of cellular networks. Frequency-division duplexing (FDD) massive MIMO systems in the downlink (DL) suffer significantly from the channel estimation overhead. In this thesis, we propose a minimum mean square error (MMSE)-based channel estimation framework that exploits the spatial correlation between the antennas at the BS to reduce the latter overhead. We investigate how the number of antennas at the BS affects the channel estimation error through analytical and asymptotic analysis. In addition, we derive a lower bound on the spectral …

Incorporating A New Class Of Uncertainty In Disaster Relief Logistics Planning, Emre Kirac

Graduate Theses and Dissertations

In recent years, there has been a growing interest among emergency managers in using Social data in disaster response planning. However, the trustworthiness and reliability of posted information are two of the most significant concerns, because much of the user-generated data is initially not verified. Therefore, a key tradeoff exists for emergency managers when considering whether to incorporate Social data in disaster planning efforts. By considering Social data, a larger number of needs can be identified in a shorter amount of time, potentially enabling a faster response and satisfying a class of demand that might not otherwise be discovered. However, …

Analysis Of Bridge Deck Sections By Pseudo-Compressibility Method Based On Fdm And Les: Improving Performance Through Implementation Of Parallel Computing, Blandine Therese Mbianda Kemayou

Graduate Theses and Dissertations

The incidence of wind on bridges produces static and dynamic loading that must be adequately addressed when designing bridges. Dynamic loading is the primary concern, as the amplitude of the structures response to the applied loading may be greatly amplified. Ideally, the bridge's properties should be designed to avoid dynamic loading. Previous investigations of wind loading on bridges consisted of measuring forces produced on scaled models of bridges within wind tunnels. However, these wind tunnel tests are costly and time consuming due to cost to fabricate and instrument the bridge cross sections. Recent advancements in computational power of computers allow …

Quantification And Characterization Of Fracture Resistance In Asphalt Concrete Based On R-Curve Method, Shu Yang

Graduate Theses and Dissertations

The application of fracture energy is widely applied in the evaluation of cracking in the laboratory for asphalt concrete. However, this single number does not provide information on the characterization of the initiation and propagation of cracks. The Resistance Curve method, or R-Curve, is widely applied in characterizing various materials including, but not limited to, metal, polymer, rock, and composite. This research R-Curve method introduces asphalt concrete through a stepwise approach. First, in chapter one, there is a literature review of the history of fracture mechanics, fracture research in asphalt concrete, and an examination of the role of R-Curve application …

Exploring The Black Space Of Compressive And Shear Modulus, Airam Marlee Morales Vega

Graduate Theses and Dissertations

Uniaxial dynamic modulus is a standard test used to determine the viscoelastic behavior of asphalt pavement materials, with the standard analysis generating a Master Curve. One alternative to the master curve approach is a Black Space diagram, which is a rheological plot that can delineate either dynamic modulus |E*| or shear modulus |G*| vs. phase angle (δ). In this study, four asphalt binders were tested with one aggregate blend. One of these four binders was unmodified and the other three were modified with polymers and acids. Additionally, Polyphosphoric acid (PPA) is compared to the more traditional SBS polymer modification. PPA …

Impact Of Extreme Summer Temperatures On Bridge Structures, Ryan Hagedorn

Graduate Theses and Dissertations

Climate change and its effect on weather in the United States is a well-documented phenomenon. In particular, extreme heat waves have become more intense, more frequent, and longer lasting, especially in the southern United States. As with much of America’s transportation infrastructure, prestressed concrete bridge girders experience the effects of these heat waves. Uneven heating of optimized bridge girder sections results in large non-linear temperature gradients. In this study, temperature was monitored in three different AASHTO I-girders to determine the vertical and transverse temperature gradients in a pre-deck placement condition. It was determined that the current design standard, which uses …

Nanofiltration Rejection Of Contaminants Of Emerging Concern From Municipal Water Resource Recovery Facility Secondary Effluents For Potable Reuse Applications, Steven Michael Jones

Graduate Theses and Dissertations

As reuse of municipal water resource recovery facility (WRRF) effluent becomes vital to augment diminishing fresh drinking water resources, concern exists that conventional barriers may prove deficient and the upcycling of contaminants of emerging concern (CECs) could prove harmful to human health and aquatic species if more effective and robust treatment barriers are not in place.

There are no federal Safe Drinking Water Act (SDWA) regulations in place specifically for direct potable reuse (DPR) of WRRF effluent. Out of necessity, some states are developing their own DPR reuse regulations. Currently, reverse osmosis (RO) is the default full advanced treatment (FAT) …

Structural Identification Of An Elevated Water Tower, James Thomas Norris

Graduate Theses and Dissertations

Elevated water tanks are generally located at higher elevations within a particular geographic area. The location and height of these structures often makes them desirable for installing wireless and cellular communications antennas. The impact of this practice on the long-term serviceability performance of the primary structure is not clear and could be an important consideration deserving further analysis. This paper presents a case study of an elevated water tank that was motivated by this particular consideration. The structure had been retrofitted with cellular antennas during its service and later experienced fatigue cracking at the fill pipe-tank interface. The owner wished …

Evaluation Of Poisson’S Ratio Of Asphalt Concrete, Elvis Alexander Castillo Camarena

Graduate Theses and Dissertations

Poisson´s ratio can be defined as the negative ratio of strains perpendicular to the load direction to the strains parallel to the loading direction. If elastic or viscoelastic models are used, Poisson´s ratio, together with elastic modulus, is a main input used to predict distresses in flexible pavement structures such as rutting and cracking. In asphalt concrete, Poisson’s ratio is commonly measured using two different testing configurations: indirect tension (IDT) and uniaxial. However, results from these two testing configuration can potentially have differences. Design methodologies such as the Mechanistic Empirical Design Guide (MEPDG, now PavementME) have been shown to be …

Field Observations And Computer Modeling Of Tornado-Terrain Interaction And Its Effects On Tornado Damage And Path, Nawfal Shihab Ahmed

Graduate Theses and Dissertations

Tornado forces on structures have been a research focus for the past decades, and some comparisons have been made to distinguish between straight boundary layer (SBL) wind and tornado wind forces on specific structures. However, very little attention has been paid to terrain effects on tornado damage and path. Available damage investigation data for four tornado locations (Joplin-2011, Tuscaloosa-2011, Parish-2011 and Mayflower-2014) is utilized to explore terrain effects on tornado damage and path. Google Earth, site visits and aerial images are employed to study the influence of terrain on an extent of damage and path variation. Additionally, a three dimensional …

Development Of The Masw Method For Pavement Evaluation, Benjamin J. Davis

Graduate Theses and Dissertations

The purpose of this research is to establish a recommended procedure for performing multichannel analysis of surface waves (MASW) on pavements as well as evaluating the ability of MASW to detect a change in shear wave velocity as damage in concrete increases. The tests for establishing a recommended procedure for performing MASW on pavements was conducted at five sites at the University of Arkansas Engineering Research Center in Fayetteville, Arkansas. The five sites consisted of three materials: asphalt, concrete, and soil (two sites were on asphalt, two were on concrete, and one was on soil). The methods evaluated at these …

Assessment Of An Industrial Type Radiant Heating System For Drying Rough Rice, Anne Adhiambo Okeyo

Graduate Theses and Dissertations

Rough rice is normally harvested at moisture contents (MCs) higher than that for safe storage. The objective for this study was to investigate the effectiveness of scaled-up infrared (IR) heating followed by tempering steps to dry freshly-harvested rough rice. An industrial type, pilot scale, IR drying equipment, designed to convey rough rice on a vibrating conveyor belt was used in this study. The heating zone of the equipment had catalytic IR emitters powered by natural gas. Freshly-harvested rough rice of long-grain pureline (cv. Cheniere), long-grain hybrid (cv. 6XP 756) and medium-grain (cv. CL 271) cultivars at initial moisture contents (IMCs) …

Investigation Of Optical Properties Of Zinc Oxide Photodetector, Tyler Chism

Graduate Theses and Dissertations

UV photodetection devices have many important applications for uses in biological detection, gas sensing, weaponry detection, fire detection, chemical analysis, and many others. Today’s photodetectors often utilize semiconductors such as GaAs to achieve high responsivity and sensitivity. Zinc oxide, unlike many other semiconductors, is cheap, abundant, non-toxic, and easy to grow different morphologies at the micro and nano scale. With the proliferation of these devices also comes the impending need to further study optics and photonics in relation to phononics and plasmonics, and the general principles underlying the interaction of photons with solid state matter and, specifically, semiconductors. For this …

Validation Of A Confocal Light Sheet Microscope Using Push Broom Translation For Biomedical Applications, Joshua Hutcheson

Graduate Theses and Dissertations

There exists a need for research of optical methods capable of image cytometry suitable for point-of-care technology. To propose am optical approach with no moving parts for simplification of mechanical components for the further development of the technology to the poin-of-care, a linear sensor with push broom translation method. Push broom translation is a method of moving objects by the sensor for an extended field of view. A polydimethylsiloxane (PDMS) microfluidic chamber with a syringe pump was used to deliver objects by the sensor. The volumetric rate of the pump was correlated to the integration time of the sensor to …

Genotoxicity Of Graphene In Escherichia Coli, Ananya Sharma

Graduate Theses and Dissertations

Rapid advances in nanotechnology necessitate assessment of the safety of nanomaterials in the resulting products and applications. One key nanomaterial attracting much interest in many areas of science and technology is graphene. Graphene is a one atom thick carbon allotrope arranged in a two-dimensional honeycomb lattice. In addition to being extremely thin, graphene has several extraordinary physical properties such as its exceptional mechanical strength, thermal stability, and high electrical conductivity. Graphene itself is relatively chemically inert and therefore pristine graphene must undergo a process called functionalization, which is combination of chemical and physical treatments that change the properties of graphene, …

Essays In Physicians Preference Items And Inventory Management Within The Healthcare Supply Chain, Mohammad A. Shbool

Graduate Theses and Dissertations

This work is composed of a number of topics in the healthcare area, which are approached separately with appropriate methodologies. The two topics deal with physician preference items via two different approaches. The first one investigates stock keeping unit (SKU) proliferation in healthcare organizations due to physician preference items (PPI). It captures perspectives of physicians and supply chain professionals about this problem through two surveys. The second topic builds a decision-making framework for the PPI selection process that can be used by healthcare organizations to make more objective decisions. A Multi-criteria decision making technique is implemented to illustrate the framework.

Prevention Of Drone Jamming Using Hardware Sandboxing, Joshua Mead

Graduate Theses and Dissertations

In this thesis, we concern ourselves with the security of drone systems under jamming-based attacks. We explore a relatively new concept we previously devised, known as hardware sandboxing, to provide runtime monitoring of boundary signals and isolation through resource virtualization for non-trusted system-on-chip (SoC) components. The focus of this thesis is the synthesis of this design and structure with the anti-jamming, security needs of drone systems. We utilize Field Programmable Gate Array (FPGA) based development and target embedded Linux for our hardware sandbox and drone hardware/software system.

We design and implement our working concept on the Digilent Zybo FPGA, which …

A Tabu Search, Augment-Merge Heuristic To Solve The Stochastic Location Arc Routing Problem, Tiffany L. Yang

Graduate Theses and Dissertations

The location arc routing problem (LARP) is a network optimization problem combining strategic facility location decisions and tactical or operational vehicle routing decisions for customer demand located on arcs of a network. The LARP seeks to locate facilities, or depots, and create vehicle delivery routes to minimize costs. The total cost is comprised of three components: fixed facility locations costs, fixed route creation (or vehicle acquisition) costs, and variable arc traversal costs. The applications of the LARP are varied and often include public services such as mail delivery, garbage collection, and street sweeping. In all of these applications, the magnitude …

Experimental And Computational Studies Of Cortical Neural Network Properties Through Signal Processing, Wesley Patrick Clawson

Graduate Theses and Dissertations

Previous studies, both theoretical and experimental, of network level dynamics in the cerebral cortex show evidence for a statistical phenomenon called criticality; a phenomenon originally studied in the context of phase transitions in physical systems and that is associated with favorable information processing in the context of the brain. The focus of this thesis is to expand upon past results with new experimentation and modeling to show a relationship between criticality and the ability to detect and discriminate sensory input. A line of theoretical work predicts maximal sensory discrimination as a functional benefit of criticality, which can then be characterized …

Correcting Current Imbalances In Three-Phase Four-Wire Distribution Systems, Vinson Joseph Jones

Graduate Theses and Dissertations

The objective of this thesis is to present the theory, design, construction, and testing of a proposed solution to unbalanced current loading on three-phase four-wire systems. The Unbalanced Current Static Compensator is the name of the prototype; herein referred to as the UCSC. The purpose of this prototype is to redistribute current between the three phases of a distribution system. Through this redistribution, negative- and zero-sequence currents are eliminated and a balanced system is seen upstream from the point of installation.

The UCSC consists of three separate single-phase H-bridge inverters that all share the same dc-link capacitor. Each of these …

Cloning, Fed-Batch Expression And Purification Of A Novel Anti-Candida Peptide And Development Of A Cleavage Resistant Variant Of Green Fluorescence Protein, Rudra Palash Mukherjee

Graduate Theses and Dissertations

This work illustrates that the intelligent design of a bioprocess for the production of peptides of various length is possible by having a prior knowledge of desired product, cell line, fermentation conditions, and choices for downstream recovery. Cloning, expression, and recovery of a novel 12-mer anti-Candida peptide served as an illustrative case for a proposed Escherichia coli platform. The antifungal peptide, expressed as a fusion to GFPUV during high call density fed-batch, was recovered from cell lysate, concentrated using ion exchange chromatography, and finally cleaved with cyanogen bromide. The platform was capable of producing active peptide capable of arresting the …

Achieving A Better Balance Between Productivity And Performance On Fpgas Through Heterogeneous Extensible Multiprocessor Systems, Abazar Sadeghian

Graduate Theses and Dissertations

Field Programmable Gate Arrays (FPGAs) were first introduced circa 1980, and they held the promise of delivering performance levels associated with customized circuits, but with productivity levels more closely associated with software development. Achieving both performance and productivity objectives has been a long standing challenge problem for the reconfigurable computing community and remains unsolved today. On one hand, Vendor supplied design flows have tended towards achieving the high levels of performance through gate level customization, but at the cost of very low productivity. On the other hand, FPGA densities are following Moore's law and and can now support complete multiprocessor …