Engineering Commons^™

Laser Direct Written Silicon Nanowires For Electronic And Sensing Applications, Woongsik Nam

Open Access Dissertations

Silicon nanowires are promising building blocks for high-performance electronics and chemical/biological sensing devices due to their ultra-small body and high surface-to-volume ratios. However, the lack of the ability to assemble and position nanowires in a highly controlled manner still remains an obstacle to fully exploiting the substantial potential of nanowires. Here we demonstrate a one-step method to synthesize intrinsic and doped silicon nanowires for device applications. Sub-diffraction limited nanowires as thin as 60 nm are synthesized using laser direct writing in combination with chemical vapor deposition, which has the advantages of in-situ doping, catalyst-free growth, and precise control of position, …

Exploring Spin-Transfer-Torque Devices And Memristors For Logic And Memory Applications, Zoha Pajouhi

Open Access Dissertations

As scaling CMOS devices is approaching its physical limits, researchers have begun exploring newer devices and architectures to replace CMOS.

Due to their non-volatility and high density, Spin Transfer Torque (STT) devices are among the most prominent candidates for logic and memory applications. In this research, we first considered a new logic style called All Spin Logic (ASL). Despite its advantages, ASL consumes a large amount of static power; thus, several optimizations can be performed to address this issue. We developed a systematic methodology to perform the optimizations to ensure stable operation of ASL.

Second, we investigated reliable design of …

Intelligent Control Of A Class Of Nonlinear Systems, Phuong D. Ngo

Open Access Dissertations

The objective of this study is to improve and propose new fuzzy control algorithms for a class of nonlinear systems. In order to achieve the objectives, novel stability theorems as well as modeling techniques are also investigated. Fuzzy controllers in this work are designed based on the fuzzy basis function neural networks and the type-2 Takagi-Sugeno fuzzy models.

For a class of single-input single-output nonlinear systems, a new stability condition is derived to facilitate the design process of proportional-integral Mamdani fuzzy controllers. The stability conditions require a new technique to calculate the dynamic gains of nonlinear systems represented by fuzzy …

Fabrication And Characterization Of Cellulose Nanocrystal Enhanced Sustainable Polymer Nanocomposites Through Surface Chemistry And Processing, Shane X. Peng

Open Access Dissertations

Cellulose nanocrystals (CNCs) belong to a class of cellulose based nanomaterials that are extracted from renewable and sustainable sources and have excellent mechanical and thermal properties. While applications for CNCs have been expanding, one of the challenges of utilizing CNCs is to overcome their low dispersibility in hydrophobic polymers. In the present work, several approaches are utilized to improve the interfacial compatibility and overall performance of CNC/epoxy and CNC/polyamide nanocomposite.

For a two-part epoxy system, a novel approach was taken to disperse CNC in epoxy matrix by pre-formulating CNC into the hardeners. Three types of hardeners were evaluated for their …

Parametric Approaches To Fractional Programs: Analytical And Empirical Study, Chong Hyun Park

Open Access Dissertations

Fractional programming is used to model problems where the objective function is a ratio of functions. A parametric modeling approach provides effective technique for obtaining optimal solutions of these fractional programming problems. Although many heuristic algorithms have been proposed and assessed relative to each other, there are limited theoretical studies on the number of steps to obtain the solution. In this dissertation, I focus on the linear fractional combinatorial optimization problem, a special case of fractional programming where all functions in the objective function and constraints are linear and all variables are binary that model certain combinatorial structures. Two parametric …

A Holistic Approach To Lowering Latency In Geo-Distributed Web Applications, Shankaranarayanan Puzhavakath Narayanan

Open Access Dissertations

User perceived end-to-end latency of web applications have a huge impact on the revenue for many businesses. The end-to-end latency of web applications is impacted by: (i) User to Application server (front-end) latency which includes downloading and parsing web pages, retrieving further objects requested by javascript executions; and (ii) Application and storage server(back-end) latency which includes retrieving meta-data required for an initial rendering, and subsequent content based on user actions.

Improving the user-perceived performance of web applications is challenging, given their complex operating environments involving user-facing web servers, content distribution network (CDN) servers, multi-tiered application servers, and storage servers. Further, …

Development Of First-Year Engineering Teams' Mathematical Models Through Linked Modeling And Simulation Projects, Kelsey Joy Rodgers

Open Access Dissertations

The development and use of mathematical models and simulations underlies much of the work of engineers. Mathematical models describe a situation or system through mathematics, quantification, and pattern identification. Simulations enable users to interact with models through manipulation of input variables and visualization of model outputs. Although modeling skills are fundamental, they are rarely explicitly taught in engineering. Model-eliciting activities (MEAs) represent a pedagogical approach used in engineering to teach students mathematical modeling skills through the development of a model to solve an authentic problem.

This study is an investigation into the impact of linking a MEA and a simulation-building …

From Mechanic To Designer: Evolving Perceptions Of Elementary Students Over Three Years Of Engineering Instruction, Anastasia M. Rynearson

Open Access Dissertations

Due in part to increasing state standards that require engineering in K-12 curricula and the Next Generation Science Standards’ incorporation of engineering outcomes, inclusion of engineering into elementary classrooms is on the rise. Teacher development and experiences in learning about and implementing engineering have been studied, but elementary students’ experiences when learning about engineering have not been explored.

The purpose of this study is to address the question: How do elementary students’ knowledge of, attitudes toward, and overall conceptions of engineering evolve over three years of engineering instruction?

This study follows seven elementary school students through three years of engineering …

Development Of Orthogonally Crosslinked Thiol-Ene Hydrogels For Encapsulation Of Pancreatic Beta-Cells, Han Shih

Open Access Dissertations

Type I diabetes mellitus (T1DM) is an autoimmune disease caused by auto-reactive T-cell-mediated destruction of insulin-producing β-cells. Effective encapsulation strategies can protect the transplanted islets from direct attack by host immune cells while maintaining insulin secretion. To achieve this goal, I have developed a hydrogel conformal coating using a visible light-mediated interfacial thiol-ene photopolymerization. Unlike conventional chain-growth visible light polymerizations, no additional cytotoxic co-initiator or co-monomer was required in thiol-ene gelation scheme for rapid gelation. More importantly, islets coated with thiol-ene gel maintained their viability and function in vitro. In addition to microencapsulate β-cells, the second objective of my …

Atomistic And Mesoscopic Simulations Of Heat Transfer Across Heterogeneous Material Interfaces, Sridhar Sadasivam

Open Access Dissertations

The study of heat transfer and the associated thermal interface resistance at heterogeneous material interfaces is over 70 years old since the first measurements of thermal interface resistance by Kapitza in 1941. However, recent developments in experimental metrology techniques that enable spectrally-resolved phonon transport measurements at the nanoscale along with the development of high-fidelity simulation methods have provided a renewed interest in the fundamental physics of heat transfer across interfaces. Miniaturized electronic devices and nanostructured materials for energy applications are among technologies that would benefit from a fundamental understanding of interfacial thermal transport. This dissertation focuses on the study of …

X-Ray Fluorescence For Quantification Of Lead And Strontium In Vivo, Aaron James Specht

Open Access Dissertations

Lead (Pb) is a toxicant well known for its effects on almost every organ system in the body. Pb use in industry has declined since removal of Pb from gasoline, but many developing countries still have significant use of Pb. Exposure to Pb has been linked with diseases causing neurodegeneration and thus have lasting effects long after the initial exposure. Another metal, strontium (Sr), has been linked with bone disease in particular situations and shown to have uses in treating osteoporosis as a supplement. However, there are no studies of the effects of Sr using a meaningful biomarker. The most …

Physical Properties, Evaporation And Combustion Characteristics Of Nanofluid-Type Fuels, Saad Tanvir

Open Access Dissertations

Nanofluids are liquids with stable suspension of nanoparticles. Limited studies in the past have shown that both energetic and catalytic nanoparticles once mixed with traditional liquid fuels can be advantageous in combustion applications, e.g., increased energy density and shortened ignition delay. Contradictions in existing literature, scarcity of experimental data and lack of understanding on how the added nanoparticles affect the physical properties as well as combustion characteristics of the resulting fuel motivated us to launch a detailed experimental and theoretical investigation.

The surface tension of ethanol and n-decane based nanofluid fuels containing suspended nanoparticles were measured using the pendant drop …

Analytical Methods For Gravity-Assist Tour Design, Nathan J. Strange

Open Access Dissertations

This dissertation develops analytical methods for the design of gravity-assist space- craft trajectories. Such trajectories are commonly employed by planetary science missions to reach Mercury or the Outer Planets. They may also be used at the Outer Planets for the design of science tours with multiple flybys of those planets’ moons. Recent work has also shown applicability to new missions concepts such as NASA’s Asteroid Redirect Mission.

This work is based in the theory of patched conics. This document applies rigor to the concept of pumping (i.e. using gravity assists to change orbital energy) and cranking (i.e. using gravity assists …

Data Driven Low-Bandwidth Intelligent Control Of A Jet Engine Combustor, Nathan L. Toner

Open Access Dissertations

This thesis introduces a low-bandwidth control architecture for navigating the input space of an un-modeled combustor system between desired operating conditions while avoiding regions of instability and blow-out. An experimental procedure is discussed for identifying regions of instability and gathering sufficient data to build a data-driven model of the system's operating modes. Regions of instability and blow-out are identified experimentally and a data-driven operating point classifier is designed. This classifier acts as a map of the operating space of the combustor, indicating regions in which the flame is in a "good" or "bad" operating mode. A data-driven predictor is also …

Implementing And Testing A Panel-Based Method For Modeling Acoustic Scattering From Cfd Input, S. Hales Swift

Open Access Dissertations

Exposure of sailors to high levels of noise in the aircraft carrier deck environment is a problem that has serious human and economic consequences. A variety of approaches to quieting exhausting jets from high-performance aircraft are undergoing development. However, testing of noise abatement solutions at full-scale may be prohibitively costly when many possible nozzle treatments are under consideration. A relatively efficient and accurate means of predicting the noise levels resulting from engine-quieting technologies at personnel locations is needed. This is complicated by the need to model both the direct and the scattered sound field in order to determine the resultant …

Improving The Resilience Of Cyber-Physical Systems Under Strategic Adversaries, Paul Wood

Open Access Dissertations

Renewable energy resources challenge traditional energy system operations by substituting the stability and predictability of fossil fuel based generation with the unreliability and uncertainty of wind and solar power. Rising demand for green energy drives grid operators to integrate sensors, smart meters, and distributed control to compensate for this uncertainty and improve the operational efficiency of the grid. Real-time negotiations enable producers and consumers to adjust power loads during shortage periods, such as an unexpected outage or weather event, and to adapt to time-varying energy needs. While such systems improve grid performance, practical implementation challenges can derail the operation of …

Visual Clutter Study For Pedestrian Using Large Scale Naturalistic Driving Data, Kai Yang

Open Access Dissertations

Some of the pedestrian crashes are due to driver’s late or difficult perception of pedestrian’s appearance. Recognition of pedestrians during driving is a complex cognitive activity. Visual clutter analysis can be used to study the factors that affect human visual search efficiency and help design advanced driver assistant system for better decision making and user experience. In this thesis, we propose the pedestrian perception evaluation model which can quantitatively analyze the pedestrian perception difficulty using naturalistic driving data. An efficient detection framework was developed to locate pedestrians within large scale naturalistic driving data. Visual clutter analysis was used to study …

Flow Shop Scheduling For Energy Efficient Manufacturing, Hao Zhang

Open Access Dissertations

A large number of new peaking power plants with their associated auxiliary equipment are installed to meet the growing peak demand every year. However, 10% utility capacity is used for only 1%~2% of the hours in a year. Thus, to meet the demand and supply balance through increasing the infrastructure investments only on the supply side is not economical. Alternatively, demand-side management might cut the cost of maintaining this balance via offering consumers incentives to manage their consumption in response to the price signals.

Time-varying electricity rate is a demand-side management scheme. Under the time-varying electricity rate, the electricity price …

Reactions Of Graphene Oxide And Buckminsterfullerene In The Aquatic Environment, Yingcan Zhao

Open Access Dissertations

Due to unique physical and chemical properties, carbon-based nanomaterials, including C60 and graphene oxide, now being used in an increasing number of applications. Considering their widespread use, nanoparticles will inevitably find their way to the natural environment. However, their environmental fate and transport have not been intensively explored, resulting in a general lack of knowledge regarding their risk assessment and life cycle exposure concentrations. To this end, this study has investigated: (i) the photo mineralization of aqu/nC60 clusters under photo irradiation, and (ii) environmental transformation of graphene oxide in the aquatic environment. This study shows that CO2 was produced from …

Flow Shop Scheduling For Energy Efficient Manufacturing, Hao Zhang

Open Access Dissertations

A large number of new peaking power plants with their associated auxiliary equipment are installed to meet the growing peak demand every year. However, 10% utility capacity is used for only 1%~2% of the hours in a year. Thus, to meet the demand and supply balance through increasing the infrastructure investments only on the supply side is not economical. Alternatively, demand-side management might cut the cost of maintaining this balance via offering consumers incentives to manage their consumption in response to the price signals.

Time-varying electricity rate is a demand-side management scheme. Under the time-varying electricity rate, the electricity price …

Laboratory Characterization Of Ohio Gold Frac Sand, Maria Gabriela Alvarado Calle

Open Access Theses

The mechanical response of sand depends on state variables (such as density, stress state and fabric) and intrinsic variables (such as particle size distribution and particle shape). The mechanical response of sand is also a function of sand crushability. Recent research studying the cone penetration process in a unique digital image correlation (DIC) chamber is underway at Purdue University. The test sand is Ohio Gold Frac sand, which meets criteria regarding particle size and gradation related to elimination of chamber boundary and scale effects.

The mechanical behavior of this sand can be simulated by a suitable constitutive model, such as …

Role Of River Bathymetry In Hydraulic Modeling Of River Channels, Sayan Dey

Open Access Theses

Accurate geometric representation of the river channel is required for accurate hydraulic modeling of rivers. These are generally obtained through remote sensing techniques such as Light Detection and Ranging (LIDAR). However, these techniques lack the ability to model the submerged channel bed effectively and need to be complemented with surveyed bathymetric data for complete representation of the channel bathymetry, which can be time and cost prohibitive. An alternative to address this issue is to develop conceptual models that can estimate bathymetry.

This study aims to evaluate the potential of a conceptual model, the River Channel Morphology Model (RCMM) which estimates …

Modeling The Impact Of Battery Degradation Within Lifecycle Cost Based Design Optimization Of Heavy-Duty Hybrid Electric Vehicles, Ashish P. Vora

Open Access Dissertations

The optimal design of hybrid electric vehicle (HEV) powertrains from a systems perspective is critical to realize the maximum benefits for a given application. This is particularly true in the heavy-duty vehicle space where the major challenges are: (i) greater emphasis on economic viability, (ii) reluctance to take on risk associated with new technologies, and (iii) numerous diverse applications that preclude a one-size-fits-all approach to hybrid-electric powertrain design. Past studies on HEV powertrain design have either ignored battery degradation, or failed to holistically capture its impact from a lifecycle cost perspective. The focus of this effort is the development of …

Fuel Type Estimation Using Fuel System Parameters, Shambhavi Balasubramanian

Open Access Theses

A number of factors are responsible for an increased interest in alternative fuels for transportation and other uses. Among the most widely available alternative fuels are biodiesel and vegetable oil, both of which can be used to power a diesel engine. Biodiesel has higher density, viscosity, surface tension, sound velocity, and bulk modulus of elasticity than regular diesel fuel. This affects the fuelling, injection timing, and fuel spray and consequently the emission characteristics.

Estimation of fuel type is critical to the performance of the engine. Knowing the fuel type allows the engine controller to determine the proper fuel quantity and …

Roundabout Maintenance Flipbook, Indiana Ltap

Indiana Local Technical Assistance Program (LTAP) Publications

This flipbook is a summary of the work published in the Roundabout Maintenance Manual by Indiana LTAP. This information was collected through a series of interviews with city engineers, public works directors, and street commissioners experienced in roundabout maintenance. It serves as a model to guide work crews in correct maintenance procedures.

Roundabout Maintenance Manual, Indiana Ltap

Indiana Local Technical Assistance Program (LTAP) Publications

This maintenance manual serves as an additional resource for communities who have imple­mented roundabouts or are considering them. There are a few other published guides, such as the NCHRP Report 672, Roundabouts: An Informational Guide, and the Wisconsin DOT Facilities Develop­ment Manual. However, the information covered in these guides is very broad. This manual provides specific information regarding roundabout maintenance.

Visualizations Of Travel Time Performance Based On Vehicle Re-Identification Data, Stanley E. Young, Elham Sharifi, Christopher M. Day, Darcy M. Bullock

Lyles School of Civil Engineering Faculty Publications

This paper provides a visual reference of the breadth of arterial performance phenomena based on travel time measures obtained from reidentification technology that has proliferated in the past 5 years. These graphical performance measures are revealed through overlay charts and statistical distribution as revealed through cumulative frequency diagrams (CFDs). With overlays of vehicle travel times from multiple days, dominant traffic patterns over a 24-h period are reinforced and reveal the traffic behavior induced primarily by the operation of traffic control at signalized intersections. A cumulative distribution function in the statistical literature provides a method for comparing traffic patterns from various …

Why This Flip Wasn't A Flop: What The Numbers Don't Tell You About Flipped Classes, Heather Noel Fedesco, Troy Cary

IMPACT Publications

This paper details the conversion of a large, required Civil Engineering fluid mechanics course into a more student-centered, active learning-oriented course through the flipping of one lecture per week. In the flipped class, students collaboratively solve homework problems in groups while receiving “expert” feedback from instructors and TAs. To offset the lost lectures, some course material that has been delivered in traditional lectures has been placed online in the form of short videos and textbook readings, with low-stakes quizzes for assessment.

Student learning gains were quantitatively assessed by comparing quiz and final exam scores for three semesters (1 pre-flip and …

Professional Development For The Integration Of Engineering In High School Stem Classrooms, Jonathan E. Singer, Julia M. Ross, Yvette Jackson-Lee

Journal of Pre-College Engineering Education Research (J-PEER)

Science, Technology, Engineering, and Mathematics (STEM) education in the U.S. is in transition. The recently published A Framework for K-12 Science Education: Practices, Crosscutting Concepts, and Core Ideas as well as the Next Generation Science Standards are responsive to this call and clearly articulate a vision that includes engineering practices as key components. This shift presents significant challenges to school districts owing to a stark lack of research-based engineering-focused instructional materials and corresponding teacher professional development. The purpose of this study was to investigate the impact of a professional development program on high school STEM teachers’ ability to enact design-based …

An Exploratory Study: Correlations Between Occupational Stressors, Coping Mechanisms, And Job Performance Among Chinese Aviation Maintenance Technicians, Yu Wang, Julius C. Keller, Chenyu Huang, Richard O. Fanjoy

Journal of Aviation Technology and Engineering

Aviation maintenance technicians play a vital role in air transportation. These workers are responsible for keeping aircraft airworthy and executing safety responsibilities. Undesirable stress levels may have a negative impact on work performance (Mowday, Porter, & Steers, 2013). Poor work performance may manifest in safety violations, absenteeism, turnover, and disengagement. These outcomes may disrupt an organization’s operation and negatively impact the financial bottom line. This mixed-methods exploratory research study was aimed at examining the relationships between occupational stress, coping mechanisms, and job performance. Research questionnaires were electronically distributed to frontline aviation maintenance technicians at multiple airlines in China. Eighty-two ( …