Engineering Commons^™

Near Sputter-Threshold Gasb Nanopatterning, Osman El-Atwani, Sean Gonderman, Jean Paul Allain

Birck and NCN Publications

Nanopatterning at sputter-threshold energies with Ar irradiation of GaSb (100) surfaces is presented. Comparison with high-energy irradiations up to 1000 eV is conducted measuring in-situ the composition evolution over irradiation time at early stages (e. g., < 10(17) cm(-2)) and up to nanostructure saturation (e. g., similar to 10(18) cm(-2)). Low-energy irradiation is conducted for energies between 15-100 eV and a low-aspect ratio nanostructured dot formation is found. Furthermore, the role of oxide on GaSb is found to delay nanostructure formation and this is predominant at energies below 100 eV. In-situ quartz crystal microbalance measurements collect sputtered particles yielding the sputter rate at threshold energies indicating a correlation between erosion and surface composition consistent with recent theoretical models. Ion-induced segregation is also found and indicated by both compositional measurements of both the surface and the sputtered plume. (C) 2013 AIP Publishing LLC.

Frequency Response Of Skin Vibration On The Head And Neck During Speech, Ben Pence, Dr. Scott Thomson

Journal of Undergraduate Research

During speech, the vocal folds vibrate resulting in audible sounds. In addition to being transmitted through the vocal tract these vibrations are also transmitted through several layers of various types of tissue throughout the head and neck, resulting in small, but measurable, skin surface vibration. Contact microphones sense these skin surface vibrations for speech transmission as opposed to acoustic microphones that sense air vibrations that radiate from the mouth.

Averting Hiv Infections In New York City: A Modeling Approach Estimating The Future Impact Of Additional Behavioral And Biomedical Hiv Prevention Strategies, Jason Kessler, Julie E. Myers, Kimberly A. Nucifora, Nana Mensah, Alexis Kowalski, Monica Sweeney, Christopher Toohey, Amin Khademi, Colin Shepard, Blayne Cutler, R. Scott Braithwaite

Publications

Background: New York City (NYC) remains an epicenter of the HIV epidemic in the United States. Given the variety of evidence-based HIV prevention strategies available and the significant resources required to implement each of them, comparative studies are needed to identify how to maximize the number of HIV cases prevented most economically.

Methods: A new model of HIV disease transmission was developed integrating information from a previously validated micro-simulation HIV disease progression model. Specification and parameterization of the model and its inputs, including the intervention portfolio, intervention effects and costs were conducted through a collaborative process between the academic modeling …

Dc, Microwave, And Noise Properties Of Gan Based Heterojunction Field Effect Transistors And Their Reliability Issues, Congyong Zhu

Theses and Dissertations

AlGaN/GaN and InAlN/GaN-based heterojunction field effect transistors (HFETs) have demonstrated great high power and high frequency performance. Although AlGaN/GaN HFETs are commercially available, there still remain issues regarding long-term reliability, particularly degradation and ultimately device failure due to the gate-drain region where the electric field peaks. One of the proposed degradation mechanisms is the inverse-piezoelectric effect that results from the vertical electric field and increases the tensile strain. Other proposed mechanisms include hot-electron-induced trap generation, impurity diffusion, surface oxidation, and hot-electron/phonon effects. To investigate the degradation mechanism and its impact on DC, microwave, and noise performance, comprehensive stress experiments were …

College Of Engineering News, Georgia Southern University

College of Engineering & Computing: News & Publications (2010-2023)

• Dr. Mujibur Khan, Assistant Professor of Mechanical Engineering, Awarded $153,000 NSF Grant

Mechanical Engineering News, Georgia Southern University

Mechanical Engineering: News & Publications (2013-2023)

• Dr. Mujibur Khan, Assistant Professor of Mechanical Engineering, Awarded $153,000 NSF Grant

Solid State Pre-Formed Electronics Adhesive (Spea), Alexander Randon Cope

Dissertations and Theses

In mobile and handheld consumer electronic markets, product use conditions drive the requirement for mechanical strength and device durability. The majority of relatively large form factor electronic components in a laptop, mobile internet device, PDA, or mobile phone use an adhesive as a stiffener to help protect the component from physical stresses imposed by daily wear and tear. Described herein is an innovative solution referred to as Solid State Pre-Formed Electronics Adhesive (SPEA), which enables a decrease in circuit board manufacturing throughput time while increasing mechanical durability with a consistent and characterized adhesive application process.

Today, many consumer electronic ODM's …

Computational Optogenetics: Empirically-Derived Voltage- And Light-Sensitive Channelrhodopsin-2 Model, John C. Williams, Jianjin Xu, Zhongju Lu, Aleksandra Klimas, Xuxin Chen, Christina M. Ambrosi, Ira S. Cohen, Emilia Entcheva

Department of Biomedical Engineering Faculty Publications

Channelrhodospin-2 (ChR2), a light-sensitive ion channel, and its variants have emerged as new excitatory optogenetic tools not only in neuroscience, but also in other areas, including cardiac electrophysiology. An accurate quantitative model of ChR2 is necessary for in silicoprediction of the response to optical stimulation in realistic tissue/organ settings. Such a model can guide the rational design of new ion channel functionality tailored to different cell types/tissues. Focusing on one of the most widely used ChR2 mutants (H134R) with enhanced current, we collected a comprehensive experimental data set of the response of this ion channel to different irradiances and voltages, …

Giant Quasiparticle Bandgap Modulation In Graphene Nanoribbons Supported On Weakly Interacting Surfaces, Xueping Jiang, Neerav Kharche, Paul Kohl, Timothy B. Boykin, Gerhard Klimeck, Mathieu Luisier, Pulickel M. Ajayan, Saroj K. Nayak

Birck and NCN Publications

In general, there are two major factors affecting bandgaps in nanostructures: (i) the enhanced electron-electron interactions due to confinement and (ii) the modified selfenergy of electrons due to the dielectric screening. While recent theoretical studies on graphene nanoribbons (GNRs) report on the first effect, the effect of dielectric screening from the surrounding materials such as substrates has not been thoroughly investigated. Using large-scale electronic structure calculations based on the GW approach, we show that when GNRs are deposited on substrates, bandgaps get strongly suppressed (by as much as 1 eV) even though the GNR-substrate interaction is weak.

Design Of Compliant Bicycle Brake, Todd R. Coon, Dr. Larry Howell

Journal of Undergraduate Research

Shimano corporation, the market leader in bicycle components, sells a class of brakes titled “Vbraketm” that has a strong braking force and travels in a horizontal motion. The V-brake (Fig. 1) uses a four-bar mechanism to direct its motion. The goal of this design project was to use new technology to achieve the same performance as the V-brake while significantly decreasing the part count and the complexity of the design.

Role Of Programmed Proteolysis During Meiosis, Vincent Matthews, G. Valentin Borner Ph.D.

Undergraduate Research Posters 2013

Meiosis is the process which forms gametes and spores for reproduction in eukaryotic cells. During the pachytene phase of meiosis I, a protein structure, called the Synaptonemal Complex (SC), forms between homologous chromosomes and creates a scaffold for genetic recombination. In yeast, the Zip1 protein is a major structural component of the SC. At restrictive temperature for meiosis, ZIP1 is required for completion of meiotic divisions. At permissive temperature ZIP1 is required for proper chromosome segregation. We observed that chemical inhibition of the proteasome, with MG132, results in arrest at prophase of meiosis I. Based on these results, we questioned …

Stabilizing Nanostructured Solid Oxide Fuel Cell Cathode With Atomic Layer Deposition, Yunhui Gong, Diego Palacio, Xueyan Song, Rajankumar L. Patel, Xinhua Liang

Chemical and Biochemical Engineering Faculty Research & Creative Works

We demonstrate that the highly active but unstable nanostructured intermediate-temperature solid oxide fuel cell cathode, La_0.6Sr_0.4CoO_3-δ (LSCo), can retain its high oxygen reduction reaction (ORR) activity with exceptional stability for 4000 h at 700 C by overcoating its surfaces with a conformal layer of nanoscale ZrO₂ films through atomic layer deposition (ALD). The benefits from the presence of the nanoscale ALD-ZrO₂ overcoats are remarkable: a factor of 19 and 18 reduction in polarization area-specific resistance and degradation rate over the pristine sample, respectively. The unique multifunctionality of the ALD-derived nanoscaled ZrO₂ overcoats, …

Bioavailable Lead In Topsoil Collected From General Aviation Airports, Jerry H. Kavouras, Randal J. Demik, Allison C. Hopkins

Biology Department Faculty Articles

Representatives of the aviation community are interested in determining the environmental effects of leaded fuel emissions from general aviation flight operations. Soil is an environmental sink for lead to accumulate over time. This study measured bioavailable lead concentrations in topsoil at three general aviation airports and at one site with no general aviation operations in order to determine if general aviation aircraft operations are contributing to the contamination of airport topsoil at levels that require remediation by law. Bioavailable refers to substances that organisms can absorb, because they have access to them. Topsoil was collected from refueling areas, run-up areas, …

A Review Of Micro-Contact Physics For Microelectromechanical Systems (Mems) Metal Contact Switches, Benjamin F. Toller, Ronald A. Coutu Jr., John W. Mcbride

Electrical and Computer Engineering Faculty Research and Publications

Innovations in relevant micro-contact areas are highlighted, these include, design, contact resistance modeling, contact materials, performance and reliability. For each area the basic theory and relevant innovations are explored. A brief comparison of actuation methods is provided to show why electrostatic actuation is most commonly used by radio frequency microelectromechanical systems designers. An examination of the important characteristics of the contact interface such as modeling and material choice is discussed. Micro-contact resistance models based on plastic, elastic-plastic and elastic deformations are reviewed. Much of the modeling for metal contact micro-switches centers around contact area and surface roughness. Surface roughness and …

Directional Thermal Emission From A Leaky-Wave Frequency-Selective Surface, Edward C. Kinzel, James Chris Ginn, Eric Z. Tucker, Jeffrey A. D'Archangel, Louis A. Florence, Brian A. Lail, Glenn D. Boreman

Electrical Engineering and Computer Science Faculty Publications

We design, fabricate, and characterize a frequency-selective surface (FSS) with directional thermal emission and absorption for long-wave infrared wavelengths. The FSS consists of an array of patch antennas connected by microstrips, the ensemble of which supports leaky-wave-type modes with forward and backward propagating branches. The branches are designed to intersect at 9.8 μm and have a broadside beam with 20-deg full width at half maximum at this wavelength. The absorption along these branches is near unity. Measurement of the hemispherical directional reflectometer shows good agreement with simulation. The ability to control the spectral and directional emittance/absorptance profiles of surfaces has …

Ds3 Web Interface, Kevin Wong, Dr. Gordon Romney

Journal of Undergraduate Research

As digital media storage is growing ever more popular, security of this data is becoming more and more important. Intruders can relatively easily alter digital files and documents. Several customers, such as the Harold B. Lee Library, the archivist of the Dead Sea Scrolls, and the Director of the Center for Earth Remote Sensing, need the assurance of data integrity, as the users of these files require unaltered content. A digital signature signing server can receive a digital file, digitally sign it, and store the digital signature with the original file. When needed, the server can regenerate the signature and …

Digital Signature Signing Server Project Management And Client Support, Frederick Penrose, Dr. Gordon Romney

Journal of Undergraduate Research

With the ever increasing move to electronic documents in every industry and field, digital security is becoming a greater concern for everyone. Various departments within BYU have the concern of distributing images to the public and in-turn persons from the public fraudulently change the images and then claim that their modified image is the original. The mission of our project was to create a method for which the integrity of the image is preserved to produce a unique “Digital Signature” on the object at the time of archival. The objective of the Digital Signature Signing Server (DS3 ) project is …

Securing Engineering For The Future: An Inquiry-Base Approach To Teaching Engineering In Grades 6-12, Ryan Anderson, Dr. Jared Berrett

Journal of Undergraduate Research

The basis behind inquiry-based learning is that questions are being asked and answers are being found. On that same note problems are being presented and solutions are being discovered. Inquiry-based learning and instruction allows for personal growth and choice in education on the part of the student. It doesn’t eliminate the role of the teacher, but it places the teacher in the position of facilitator. The goal of the facilitator is to create an environment where students can begin to make connections with previous learning, add to that learning new knowledge, and then form their own conclusions to find solutions.

Friction Stir Welding Of Hsla Steel, Sterling Anderson, Dr. Tracy Nelson

Journal of Undergraduate Research

In response to industrial need for a high-strength, weldable, malleable, and corrosion resistant steel the United States Navy developed a high-strength, low-alloy steel known as HSLA 65. Because of its superior mechanical properties and low cost, HSLA 65 is being increasingly used in pipeline, naval, and automotive industries. The important structural role it plays in these industries requires not only that it be weldable, but that, once welded, it maintain specified strength, ductility, and chemical composition values to avoid failure during extreme loading conditions. To achieve these properties, HSLA requires an efficient welding method that will not degrade its strength. …

Evaluation Of Numerical Models For Prediction Fatigue Life Of Cement-Treated Pavement Base Layers, Rebecca Crane, Dr. W. Spencer Guthrie

Journal of Undergraduate Research

Cement treatment of aggregate base materials has been utilized in pavement construction since the 1930s (1). The addition of cement increases the strength and stiffness of the treated material and therefore offers greater structural support to the surface layer and greater protection of the underlying subgrade. However, the use of excessive amounts of cement can produce overly stiff base materials that exhibit brittle behavior under heavy traffic loading; the susceptibility of cement-treated base (CTB) materials to cracking increases with increasing stiffness.

Microfabrication Of Electron Sources, Jeffrey Maas, Dr. Aaron Hawkins

Journal of Undergraduate Research

Microfabrication of Electron Sources as it applies to Chemical Sensors has been a useful project. With the decreasing dimensions of the handheld mass spectrometer it is becoming increasingly more important to develop an on board electron source for localized source emission. This project has been undertaken as of November of 2005 and continues to be an important aspect of research. This project has proven to be one of larger proportions than envisioned at first outset. Despite all that has yet to be done progress has been made. Sacrificial Layers have been identified as well as potential metals for the electron …

Improving Micro Air Vehicles, Andrew Hosford, Dr. Deryl Synder

Journal of Undergraduate Research

Recently, there has been increased interest in the development of micro air vehicles (MAVs) (Figure 1) to perform reconnaissance, surveillance, and other small operations best suited for air vehicles with maximum dimensions of six inches. In order to develop successful air vehicles, it is imperative to have correct fluid flow modeling. As of late, current modeling tools used to design and analyze full-scale aircraft do not work well for MAVs[1]. This lack of appropriate tools has lead current research to take a trial and error approach to design of MAVs—a very expensive and inefficient technique.

Synthesis Of A Polymeric Micelle That Can Target And Attach To Specific Tissues, Douglas S. Lewis, Dr. William Pitt

Journal of Undergraduate Research

In the past decade, many efforts have been made to improve chemotherapeutic treatments for cancer patients. One of the specific efforts seeks to actively deliver anti-cancer drugs to the target tissue rendering the chemotherapy more efficient and less damaging to nearby uninfected cells.

Peo-Ppo-Pla: An Anti-Cancer Drug Carrier Subtitle (If Applicable), James Lattin, Dr. William Pitt

Journal of Undergraduate Research

For over a decade ultrasound enhanced drug delivery systems have been under development. These systems often use polymeric molecules that form micelles. In aqueous solutions (such as blood), a spherical micelle is formed as the hydrophilic ends of the molecules interact with the solution and the hydrophobic ends are pushed to the inside of the sphere where they can interact with each other.

Numerical Modeling Of Chloride Profiles In Concrete Bridge Decks With Stay-In-Place Metal Forms, Aimee Worthen Birdsall, Dr. Spencer Guthrie

Journal of Undergraduate Research

Chloride penetration into concrete is the main cause of the rapid deterioration of concrete structures due to corrosion of reinforcing steel . This problem is especially a concern in chloride-laden environments. However, these chlorides cannot stop being applied because they are applied as deicing salts to maintain traffic during winter months. A solution many departments of transportation have investigated is to cut off the transportation path of these aggressive ions by adding a barrier between the concrete surface and the chloride agents . However, departments of transportation vary in their ideas about when this surface treatment should be applied.

Real-Time Path Planning For Unmanned Air Vehicles, Andrew Curtis, Dr. Randal Beard

Journal of Undergraduate Research

Unmanned Air Vehicles (UAVs) have become an important research topic in recent years. Military and civilian groups desire to use UAVs for several purposes, including surveillance, search and rescue, communications relays, and warfare. In the MAGICC Lab at BYU, we are researching low-cost methods of using miniature UAVs (wingspan of less than 2 meters) for these applications. We have developed a small autopilot to fly these UAVs and are able to give them commands by wireless communication from a laptop that is used as a ground station. With this research platform, we are able to easily test our methods and …

Managing Traffic On The Information Super Highway, Robert W. Walthall, Dr. Mark Clement

Journal of Undergraduate Research

This research was conducted to determine the effectiveness of a method of controlling the flow of traffic on the information highway. A new network protocol, Asynchronous Transfer Mode, is being developed to support applications that will run on the infohighway. These applications will include current data transfers such as surfing the net and carrying local area network traffic across the country, but it will also support things like video on demand, distance learning, and video conferencing.

Base Enlarged Microfluidic Channels For Capillary Chromatography And Electrophoresis, Craig L. Christianson, Dr. Aaron Hawkins

Journal of Undergraduate Research

The purpose of this project is to build a microfluidic channel using the planar thin film method while increasing the cross-sectional area of the channel by extending the base of the channel down into the substrate.

Evaluation Of A Compliant Out-Of-Plane Micro-Mechanical Mechanism, Jeff Young, Dr. Larry Howell

Journal of Undergraduate Research

Much research is being done around the world in the field of micro-electro-mechanical systems (MEMS). MEMS are devices such as linkages, actuators, gears and motors built on a scale of microns. MEMS have many potential applications in medical science, electronics and other areas where smaller, more intricate, and more innovative solutions are continually required. Essential to the practicality of MEMS is the ability to design for predictable and reliable behavior. The extremely small size of these devices presents difficulty in realizing a design. Joining separate elements into operative assemblies is very difficult at the micro scale. A sound solution to …

Stress-Induced Development Of Human Vocal Fold Morphology, Kendall Teichert, Dr. Scott Thomson

Journal of Undergraduate Research

Ramig and Verdolini state: “it has been estimated that 3% to 9% of the total population in the United States has a voice disorder.” One way to better understand voice disorders is to learn about the development of the structures and properties, or morphology, they affect. Much study has been done on the morphology of the human vocal folds. As explained by Hirano et al the vocal fold is made up of two parts: a cover (mucosa) and body (muscle). Hirano further explains that the mucosa is composed of various layers which include the mucosa epithelium and the lamina propria. …