Engineering Commons^™

A Study On The Effect Of Random Placement And Orientation On The Resonance Of Multiple Split Ring Resonators, Michael Buscher

Electrical Engineering Undergraduate Honors Theses

This thesis project experimentally studies the effect of placing split-ring oscillators (SRR) in a non-periodic arrangment with random orientation. This is contrary to typical structures which are simulated as a single unit cell with a periodic boundry condition to emulate an infinite array of SSR's. Samples are measured using a near-field free-space measurement system with full Thru, Reflect, Line (TRL) calibration and the application of time domain gating. Results, in the form of scattering (S) parameters, are compared with previous measurments of periodic SRR structures in order to study the influence, if any, of periodicity in the frequency response of …

Morphology Of Ingaas Multilayer Nanostructure On Gaas High-Index Surfaces, Yanze Xie

Graduate Theses and Dissertations

This work aimed to explore nanostructure configuration by growing multiple layers of strained InGaAs on GaAs high index surface. The knowledge learned would help to achieve a comprehensive picture of strain-driven nanostructure evolution. Ordered arrays of InGaAs quantum dots were demonstrated on GaAs(311)B. The ordering patterns depended on the thickness of GaAs interlayer between InGaAs Quantum Dots (QDs). With an increased interfacial thickness, a transition from two dimensional (2D) lateral ordering to 1D dot chains was observed. InGaAs growth on GaAs(311)A and GaAs(331)A ended up with 1D quantum wires (QWRs). Straight InGaAs QWRs were uniformly distributed across the surfaces owing …

Factors Affecting Redox Magnetohydrodynamics For Flow In Small Volumes, Matthew D. Gerner

Graduate Theses and Dissertations

Lab-on-a-chip technologies offer the possibility of developing analytical devices that are low-cost, portable, disposable, fast, and operable by non-technical personnel. Such devices require automated methods to manipulate ultra-small volumes (picoliters) of samples and solution, including pumping, stirring, and positioning. Current methods for ultra-small volume microfluidics have limitations that restrict their use including high voltage requirements, disadvantageous flow profiles or rates, and relatively complicated fabrication due to mechanical parts. Redox magnetohydrodyanmics (RMHD) that utilizes permanent magnets for portability shows promise as a micropump with ease of switching flow direction, no moving parts, compatibility with both aqueous and non-aqueous solutions, low voltages …

Proton Irradiation Effects On Semiconductor Cdse/Zns Core/Shell Nanocrystals, Stephen Graham Charter

Graduate Theses and Dissertations

The absorbance and photoluminescence measurement of semiconductor CdSe/ZnS core shell nanocrystals were reviewed and investigated after they were exposed to proton irradiation. The CdSe/ZnS core shell nanocrystals of 3.2nm and 4.4nm were commercially purchased and investigated. These nanocrystals were embedded in UV resin. Proton irradiation of energy 2MeV was applied at doses from 3 x 1013 protons cm-2 to 1.47 x 1015 protons cm-2 for both nanocrystal sizes. Absorbance measurements were conducted at 300K. Results from absorbance measurements showed slight broadening of the first exciton peak of both samples but was most noticeable in the 3.2nm nanocrystal sample. UV resin …

Carbon Nanotube Cluster Based Micro-Fluidic System For Bacteria Capture, Concentration, And Separation, Christopher Nelson

Biological and Agricultural Engineering Undergraduate Honors Theses

Disease-causing pathogens continue presenting enormous global health problems, especially due to their easy transmittance to people via water supply systems. The detection, filtration, and purification of bacteria contaminated water samples are complex and subject to a great amount of error. Here we present a new and highly effective micro-fluidic system with carbon nanotube clusters for effective and efficient detection, filtration, and purification of bacteria contaminated medium. The developed system is based upon two unique properties of carbon nanotubes (CNTs): high bacterial affinity and magnetic susceptibility. The CNTs' high affinity to bacteria cells makes them a key candidate for the bacteria …

Analysis Of Ecosystem Services At Mullins Creek On The University Of Arkansas Campus, Kathryn Mccoy

Biological and Agricultural Engineering Undergraduate Honors Theses

The University of Arkansas has been a site of population and urban growth since its inception in 1871. This urban development has caused extreme changes in land use, and with this has also come a change in ecosystem services provided by the area. Ecosystem services are benefits acquired by humans that are provided by functions are an ecosystem (Constanza et al., 1997). Constanza developed a method for quantifying ecosystem services. In this method, Constanza valuated ecosystem services for biomes. These service values were based on the economic value of the service provided, and were given in dollar per hectare-year. A …

Detection Of Escherichia Coli Using The Bacteriophage-Based Fluorescent Technique, Aung Khaing

Biological and Agricultural Engineering Undergraduate Honors Theses

The detection of viable Escherichia coli (E. coli) by the bacteriophage-based fluorescent technique using the enhanced green fluorescent protein (EGFP) was tested in this project. EGFP, a mutant of green fluorescent protein (GFP), was used due to its high fluorescent efficiency compared to wild-type GFP. First, E. coli bacteria were cultured to the mid-exponential phase in the 2× YT medium and then they were infected with the M13 bacteriophages containing the EGFP gene. Infected bacteria were incubated for different time intervals, and the expression of EGFP on the E. coli membrane was tested by the PerkinElmer LS 55 Luminescence Spectrometer, …

Hot Mix Asphalt Longitudinal Joint Evaluation, Annette Porter

Civil Engineering Undergraduate Honors Theses

Longitudinal joints are the portion of the road where two lanes meet and are formed because the lanes are paved at different times. Longitudinal joints tend to be the weakest portion of the roadway, and yet few regulations exist to control their quality. Currently, Arkansas specifications for asphalt pavement do not include any requirements for the measurement of joint quality. The purpose of this research project is to determine the most effective method for evaluating longitudinal joints in hot-mix asphalt (HMA) pavements. Most of the literature concerning longitudinal joints focuses on density as the determining factor of quality because density …

Developing Equivalent Second Order System Models And Robust Controls For Servo-Drive Related Systems, Christopher Hoyt

Electrical Engineering Undergraduate Honors Theses

Numerous industrial and other plant processes today represent systems in which a motor supplies torque to a drive disk, which in turn through a pulley system drives a larger load. Developing models for these complex systems can become time consuming and expensive. A simple second order system approximation can be developed for these systems under certain system conditions which can greatly reduce the complexity of controlling and modeling the system. A second order feed-forward notch controller can then be introduced to the system which greatly improves performance. The results of this proposed method of approximating complex servo-drive systems show that …

Preliminary Study Based On The Ddscat Software To Explore Increasing The Contrast Of Breast Tumors For Microwave Imaging, Rachel Megee

Electrical Engineering Undergraduate Honors Theses

Microwave technology is being researched for its capabilities to detect breast tumors less painfully and at earlier stages. It is necessary to have a large contrast between cancerous and healthy tissue when the microwaves are reflected off the breast tissue. To model the increasing contrast between cancerous breast tissue and healthy breast tissue, the DDSCAT code is investigated for its capabilities and analyzed for its accuracy in scattering calculations. The DDSCAT is used to model homogenous and inhomogeneous targets. Simulations of the scattering field by the homogeneous and inhomogeneous targets are conducted and compared to Mie theory calculations for accuracy. …

Analysis Of Phase Ii Metabolites Of Methamphetamine By Solid-Phase Extraction And Liquid Chromatography With Tandem Mass Spectrometric Detection, Jordan Carbary, Howard P. Hendrickson

Biological and Agricultural Engineering Undergraduate Honors Theses

Methamphetamine (METH) abuse is one of the most serious health problems in the United States and Europe due to its addictive properties and potential neurotoxic effects [1, 2, 3]. METH abuse appears to have stabilized or decreased slightly in the general populations, however abuse in certain populations is increasing [4, 5]. Treatments for drug abuse are often tested in animal behavioral pharmacology models. One of the first in vivo tests conducted in animals is to follow the concentration of the drug and its metabolites as a function of time. In this way, one can determine how long a potential medication …

Computational Modeling Of The Internal Structure In The Breast, Jordan Greenlee

Electrical Engineering Undergraduate Honors Theses

Many researchers who are using microwave modality in the area of breast cancer detection employ oversimplified models of the internal structure of the breast. Use of engineered or biologically inaccurate models could render inaccurate results. Therefore, a mathematical biological model is implemented in this work and aims to bridge the gap between biologists and engineers. The results of the proposed breast duct model show that older women have smaller breast ducts leading to less dense breasts, which is in agreement with medical knowledge. Also, younger women have larger breast ducts leading to more dense breasts which are consistent with the …

Droplet Assisted Self-Assembly Of Semiconductor Nanostructures, Kimberly Annosha Sablon

Graduate Theses and Dissertations

There is increasing interest in quantum dot (QD) structures for a plethora of applications, including optoelectronic devices, quantum computing and energy harvesting. While strain driven surface diffusion via stranski-krastanow (SK) method has been commonly used to fabricate these structures, a more recent technique, droplet epitaxy (DE) does not require mismatch strain and is therefore much more flexible in the combination of materials utilized for the formation of QDs.

As reported in this work, a hybrid approach that combines DE and SK techniques for realizing lateral ordering of QDs was explored. First, the droplet formation of various materials was discussed and …

Specificity Analysis Of Site-Directed Mutated Glucose Indicator Proteins, Tanushree Thote

Biological and Agricultural Engineering Undergraduate Honors Theses

Specificity analysis of site-directed mutated glucose indicator proteins

Development Of A Distributed Artificial Neural Network For Hydrologic Modeling, Rebecca Logsdon

Biological and Agricultural Engineering Undergraduate Honors Theses

Development of a distributed artificial neural network for hydrologic modeling

Low Voltage, Low Power, Bulk-Driven Amplifier, Shama Huda

Electrical Engineering Undergraduate Honors Theses

The importance of low voltage and low powered electronics is increasing with advances in medical electronics. This branch of electronics specifically requires low voltage and low power to make efficient innovative medical equipment. Low power electronics are also desirable because it conserves energy and power. This paper proposes a design of a differential in - differential our amplifier that uses a bulk-driven differential pair for the input pair. In addition, it also used bulk-driven current mirrors for the tail current sink and the active loads. The bulkdriven technique helps to achieve the low voltage design. 90nm CMOS technology was considered …

A Computational Model Of Breast Ducts, Jordan Greenlee

Inquiry: The University of Arkansas Undergraduate Research Journal

Ductal Carcinoma represents almost 75% of breast cancer. In this specific type of cancer. malignant cells in the breast ducts invade the surrounding healthy tissue. Almost all researchers who are investigating microwave modality in the area of breast cancer detection employ oversimplified models of the internal structure of the breast. Use of engineered or biologically inaccurate models can render inaccurate results. Therefore. a mathematical biological model was implemented in this work aiming to bridge the gap between physiologists and engineers. The result show that the proposed breast duct model has the capability of modeling the breast ducts of different kinds …