Engineering Commons^™

Property Enhancements Of Dielectric Nanoparticles Via Surface Functionalization, Andrew Byro

Dissertations, Theses, and Capstone Projects

This thesis describes the surface modification of barium strontium titanate nanoparticles for use in polymer/ceramic composite thin film capacitors with resultant improved dielectric and film-making properties. Phosphonic acid-type ligands proved to be most effective for surface conjugation to the surface of the barium strontium titanate nanoparticles. Amine-terminated ligands proved to be effective at removing surface adsorbed water before being almost entirely removed during the sample washing stage. Carboxylic acid terminated ligands proved to adhere less well to the nanoparticle than the phosphonic acid, but resulted in thin films with a higher dielectric constant, which was more stable in the measured …

Hydrodynamic And Mass Transport Properties Of Microfluidic Geometries, Thomas F. Leary

Dissertations, Theses, and Capstone Projects

Microfluidic geometries allow direct observation of microscale phenomena while conserving liquid volumes. They also enable modeling of experimental data using simplified transport equations and static force balances. This is possible because the length scales of these geometries ensure low Re conditions approaching the Stokesian limit, where the flow profile is laminar, viscous forces are dominant and inertial forces are negligible. This work presents results on two transport problems in microfluidic geometries. The first examines the heterogeneous binding kinetics in a microbead array, where beads with different chemical functionalities are sequentially captured in a well geometry over which analyte solution is …

Reliability-Based Progressive Collapse And Redundancy Analysis Of Bridge Systems, Feng Miao

Dissertations, Theses, and Capstone Projects

Highway bridges like most structural systems are usually designed on a member by member basis and little consideration is provided to the effect of a local failure on system safety. There are concerns that some systems optimized to meet code-specified member design criteria may not provide sufficient levels of structural redundancy to withstand a possible local failure. In fact, a local failure of one structural element may result in the failure of another element creating a chain reaction that might progress throughout the whole structure or a major portion of it leading to a catastrophic collapse. Several recent catastrophic structural …

Colloidal Quantum Dot Based Photonic Circuits And Devices, Nicky E. Okoye

Dissertations, Theses, and Capstone Projects

Colloidal quantum dots have desirable optical properties which can be exploited to realize a variety of photonic devices and functionalities. However, colloidal dots have not had a pervasive utility in photonic devices because of the absence of patterning methods. The electronic chip industry is highly successful due to the well-established lithographic procedures. In this thesis we borrow ideas from the semiconductor industry to develop lithographic techniques that can be used to pattern colloidal quantum dots while ensuring that the optical properties of the quantum dots are not affected by the process. In this thesis we have developed colloidal quantum dot …

On The Merits Of Deploying Tdm-Based Next-Generation Pon Solutions In The Access Arena As Multiservice, All Packet-Based 4g Mobile Backhaul Ran Architecture, Syed Rashid N. Zaidi

Dissertations, Theses, and Capstone Projects

The phenomenal growth of mobile backhaul capacity required to support the emerging fourth-generation (4G) traffic including mobile WiMAX, cellular Long-Term Evolution (LTE), and LTE-Advanced (LTE-A) requires rapid migration from today's legacy circuit switched T1/E1 wireline and microwave backhaul technologies to a new fiber-supported, all-packet-based mobile backhaul infrastructure. Clearly, a cost effective fiber supported all-packet-based mobile backhaul radio access network (RAN) architecture that is compatible with these inherently distributed 4G RAN architectures is needed to efficiently scale current mobile backhaul networks. However, deploying a green fiber-based mobile backhaul infrastructure is a costly proposition mainly due to the significant cost associated with …

Policy Makers’ Influence On The Emergence Of A New Scientific Discipline: The Case Of Nanotechnology In Ireland, Nicolas Battard

Doctoral

Science has undergone tremendous changes since World War II with the blurring of boundaries between science, government, and industry, as well as the so-called convergence of scientific disciplines. Nanotechnology is an illustrative example of this phenomenon. Boundaries between all these spheres are challenged, renegotiated, and reshaped under the influence of the multiple actors involved. I question here the extent to which nanoscience and nanotechnology (N&N) are emerging as a new scientific discipline under the influence of science and technology policies. With the study of N&N in Ireland from the late 1990s onwards, a focus is placed on both the macro-meso …

Evaluation Of Electrocoagulation For The Removal Of Chromium (Vi) From Brackish Groundwater, Shaima S Hamdan

Theses

Electrocoagulation (EC) has been evaluated for the removal of Cr (VI) from brackish groundwater using three different bench-scale EC reactors, namely batch stirred tank reactor (BSTR), continuous stirred tank reactor (CSTR) and a continuous electrocoagulation column (ECC). Batch EC process was experimentally examined at room temperature and the results indicated that Fe-Fe electrode pair was the most efficient arrangement and was able to achieve 100 % Cr removal at an electrocoagulation time of 5 minutes, a current density of 7.94 mA/cm², and pH of 8. A kinetic study of batch EC was then performed using both pseudo-first-order and …

Characterization If Li-Air Batteries Influence Of Cathode Degradation: Demonstration Of Progress, Claudia Torres Garibay, Jeremiah Deboever

TREC Project Briefs

Li-air batteries are attractive candidates to be used in electric vehicles (EV) due to their high theoretical capacity, which results in an improved range, a requirement to make EV competitive against fossil fuel powered vehicles. However, Li-air battery technology is considered to be far from commercialization, due to its short lifespan. The decomposition of the electrolyte and its effect on cyclablity has been widely studied, no so much the cathode. The presence of undesirable reaction by-products at the cathode that affect the battery performance has been quantified through XRD and SEM. This work will make use of recently reported novel …

Magnetic Janus Particles And Their Applications, Bin Ren

Dissertations, Theses, and Capstone Projects

Magnetic properties are important since they enable the manipulation of particle behavior remotely and therefore provide the means to direct a particle’s orientation and translation. Magnetic Janus particles combine magnetic properties with anisotropy and thus are potential building blocks for complex structures that can be assembled from a particle suspension and can be directed through external fields. In this thesis, a method for the fabrication of three types of magnetic Janus particles with distinct magnetic properties is introduced, the assembly behavior of magnetic Janus particles in external magnetic and electric fields is systematically studied, and two potential applications of magnetic …

High-Efficiency Thermodynamic Power Cycles For Concentrated Solar Power Systems, Marc T. Dunham, Brian Iverson

Faculty Publications

This paper provides a review of high-efficiency thermodynamic cycles and their applicability to concentrating solar power systems, primarily focusing on high-efficiency single and combined cycles. Novel approaches to power generation proposed in the literature are also highlighted. The review is followed by analyses of promising candidates, including regenerated He-Brayton, regenerated CO2-Brayton, CO2 recompression Brayton, steam Rankine, and CO2-ORC combined cycle. Steam Rankine is shown to offer higher thermal efficiencies at temperatures up to about 600 ˚C but requires a change in materials for components above this temperature. Above this temperature, CO2 recompression Brayton cycles are shown to have very high …

Quadrotors And Accelerometers: State Estimation With An Improved Dynamic Model, Robert C. Leishman, John Macdonald, Randal W. Beard, Timothy W. Mclain

Faculty Publications

The article examines consequences and practical aspects of using an improved dynamic model for quadrotor state estimation with only IMU measurements. The improved model correctly explains the measurements available from the accelerometers on a quadrotor. We give a brief tutorial to explain the difference between accelerometer measurements on a ground vehicle and a quadrotor. We demonstrate several observers based on the improved model to illustrate the estimation improvements available. It is shown that the parameters for this model can be estimated as elements of the state, which makes the model simple to implement and utilize. Finally, we provide hardware results …

A Dns Evaluation Of Mixing Models For Transported Pdf Modelling Of Turbulent Nonpremixed Flames, Alex Krisman, Joshua C.K. Tang, Evatt R. Hawkes, David O. Lignell, Jacqueline H. Chen

Faculty Publications

Transported probability density function (TPDF) methods are well suited to modelling turbulent, reacting, variable density flows. One of the main challenges to the successful deployment of TPDF methods is accurately modelling the unclosed molecular mixing term. This study examines three of the most widely used mixing models: the Interaction by Exchange with the Mean (IEM), Modified Curl (MC) and Euclidean Minimum Spanning Tree (EMST) models. Direct numerical simulation (DNS) data-sets were used to provide both initial conditions and inputs needed over the course of the runs, including the mean flow velocities, mixing frequency, and the turbulent diffusion coefficient. The same …

Rate Alterable Traumatic Brain Injury Device For Rodent Models, Radia Abdul Wahab

Dissertations

Traumatic Brain Injury (TBI) is a physical impact to the head resulting in functional deficits in memory and motor systems. TBI is a prevalent problem occurring in 1.7 million people annually in the United States (Faul et al. 2010). TBIs can differ greatly in terms of the biomechanics of the impact such as magnitude, direction and rate. Indeed, it is likely that the wide range of TBI outcomes may be due to the physical characteristics of the trauma. Studies to date on impact have used injury devices with limited alterable parameters. Therefore, the existing impact studies have considered the effect …

The Effect Of Mechanical Vestibular Stimulation On Muscle Tone And Spasticity In Individuals With Neurological Impairment, Ghaith J. Androwis

Dissertations

In the desire to better understand spasticity mainly in Cerebral Palsy (CP) and to examine vestibular stimulation as a future intervention for .muscle tone reduction, and to be able to describe the change in level of spasticity in subjects with disability and describe interventions effects, a series of experiments are done on children with spasticity. In addition to understanding the otoliths in the vestibular system and their projections, properties and pathways a more important major objective of this work is to validate the changes in otoliths signal caused by vestibular stimulation based on the Equilibrium Point Hypothesis and the inclusion …

Analyses Of Groundwater Contribution To A Riverine Wetland, Farzad Mahmoodinobar

Dissertations

Rainfall, runoff, overbank flow and groundwater, all contribute water to wetlands. Each transport element is associated with unique modeling approaches and uncertainties. Transpiration is perhaps the hardest to quantify as it is subject to all the variability of plant growth. Transpiration causes land area to lose moisture and the loss amount depends on precipitation incidence, the temperature and type and extent of vegetation. Plants can intercept virtually all recharge during the growing season and almost none from late fall to early spring in northeastern United States. Thus, an improvement in the transpiration element can contribute considerably to an improved groundwater …

Discrete Element Method Based Scale-Up Model For Material Synthesis Using Ball Milling, Priya Radhi Santhanam

Dissertations

Mechanical milling is a widely used technique for powder processing in various areas. In this work, a scale-up model for describing this ball milling process is developed. The thesis is a combination of experimental and modeling efforts.

Initially, Discrete Element Model (DEM) is used to describe energy transfer from milling tools to the milled powder for shaker, planetary, and attritor mills. The rolling and static friction coefficients are determined experimentally. Computations predict a quasi- steady rate of energy dissipation, Ed, for each experimental configuration. It is proposed that the milling dose defined as a product of Ed and milling …

Construction And Assessment Of A Computer Graphics-Based Model For Wheelchair Propulsion, Brooke Marie Odle

Dissertations

Upper limb overuse injuries are common in manual wheelchair using persons with spinal cord injury (SCI), especially those with tetraplegia. Biomechanical analyses involving kinetics, kinematics, and muscle mechanics provide an opportunity to identify modifiable risk factors associated with wheelchair propulsion and upper limb overuse injuries that may be used toward developing prevention and treatment interventions. However, these analyses are limited because they cannot estimate muscle forces in vivo. Patient-specific computer graphics-based models have enhanced biomechanical analyses by determining in vivo estimates of shoulder muscle and joint contact forces. Current models do not include deep shoulder muscles. Also, patient-specific models …

Extracting Product Development Intelligence From Web Reviews, Ismail Artun Yagci

Dissertations

Product development managers are constantly challenged to learn what the consumer product experience really is, and to learn specifically how the product is performing in the field. Traditionally, they have utilized methods such as prototype testing, customer quality monitoring instruments, field testing methods with sample customers, and independent assessment companies. These methods are limited in that (i) the number of customer evaluations is small, and (ii) the methods are driven by a restrictive structured format. Today the web has created a new source of product intelligence; these are unsolicited reviews from actual product users that are posted across hundreds of …

Influence Of Beach Hydrodynamics On Saltwater Transport And Oil Persistence In Beaches, Ali Abdollahi-Nasab

Dissertations

The exchange of water and solutes across the aquifer-ocean interface plays an important ecological role in both aquifer and the open water. Saltwater intrusion could prevent utilization of groundwater for either drinking water or irrigation. In addition, the flux of solutes, such as nutrients, from inland groundwater sources plays an important role in shoreline ecology, especially in embayments. This research relies on a three-pronged approach, involving a laboratory beach experiment, field scale experiments and numerical analyses. The laboratory beach experiment is designed to investigate the fundamental processes occurring in beach aquifers. It explores the effects of buoyancy (or lack thereof) …

Performance Analysis And Scheduling Strategies For Ambulatory Surgical Facilities, Xuanqi Zhang

Dissertations

Ambulatory surgery is a procedure that does not require an overnight hospital stay and is cost effective and efficient. The goal of this research is to develop an ASF operational model which allows management to make key decisions. This research develops and utilizes the simulation software ARENA based model to accommodate: (a) Time related uncertainties – Three system uncertainties characterize the problem (ii) Surgery time variance (ii) Physician arrival delay and (iii) Patient arrival delay; (b) Resource Capture Complexities – Patient flows vary significantly and capture/utilize both staffing and/or physical resources at different points and varying levels; and (c) Processing …

Computational Optimization Methods For Modeling The Effect Of Muscle Forces On Bone Strength Adaptation, Catherine Siena Florio

Dissertations

An improved understanding of the mechanical influences that alter the strength of a bone can aid in the refinement of the wide array of currently available techniques to counteract the losses of bone strength that occur due to age or disuse both on Earth and in Space. To address this need, computational modeling methods to quantitatively analyze and compare the effects of mechanical factors on the strength of a targeted bone within a multibone, multimuscle system are developed and implemented in this work. Through a more detailed representation of the system in which the bone acts and the creation of …

A Progress Report On The Ultrasound Enhancement Of Antibiotic Action On Streptococcus Pneumoniae, Michael Le Bras, Dr. William G. Pitt

Journal of Undergraduate Research

Previous studies show that using antibiotic treatment together with ultrasound enhances the bactericidal effect of antibiotics on many bacterial species (6). The purpose of this research project is to apply these techniques to Streptococcus pneumoniae and the antibiotics ampicillin and gentamicin sulfate. The effectiveness of ampicillin and gentamicin sulfate coupled with the application of ultrasound on S. pneumoniae is the focus of this study.

In Vitro Modeling And Analysis Of Axon Stretch Growth For The Sustained Growth Of Long Nerve Fibers, Joseph Rocco Loverde

Dissertations

The integration of long nerve fibers throughout the body is distinctive among somatic tissues. Single, individual motor neurons grow to a meter in length or more as they maintain connectivity with sacral areas of the spinal cord from the brain. Similarly, homologous growth also occurs via spinal ganglion neurons within the peripheral nervous system. The most widely studied aspect of nerve development has been the migration and extension of growth cones towards synaptic targets during early development. However, following growth cone extension, axonal fibers continue to grow in synchrony with the expansion of limbs and mit otic tissues throughout childhood …

Differentiating Schizophrenic Patients From Healthy Control; Application Of Machine Learning To Resting State Fmri, Hossein Ebrahimi Nezhad

Theses

In recent years, one analysis approach that has grown in popularity is the use of machine learning algorithms to train classifiers to decode stimuli, mental states, behaviors and other variables of interest from fMRI data. Most of these studies focus on fMRI low frequency oscillations. This study focuses on the amplitude of low-frequency fluctuations (ALFF) and fractional amplitude of low-frequency fluctuations (fALFF). A Voxel-wise analysis is performed on the whole brain for two groups of subjects. A machine learning algorithm is applied to two independent groups of subjects (a total of 160 healthy control and schizophrenic subjects) to classify Schizophrenia …

Providing Flexible File-Level Data Filtering For Big Data Analytics, Lei Xu, Ziling Huang, Hong Jiang, Lei Tian, David Swanson

School of Computing: Technical Reports

The enormous amount of big data datasets impose the needs for effective data filtering technique to accelerate the analytics process. We propose a Versatile Searchable File System, VSFS, which provides a transparent, flexible and near real-time file-level data filtering service by searching files directly through the file system. Therefore, big data analytics applications can transparently utilize this filtering service without application modifications. A versatile index scheme is designed to adapt to the exploratory and ad-hoc nature of the big data analytics activities. Moreover, VSFS uses a RAM-based distributed architecture to perform file indexing. The evaluations driven by three real-world analytics …

Influence Of Grass Hedges On The Transport Of Antimicrobials, Antimicrobial Resistance Genes, And Antimicrobial Resistant Pathogens After Land Application Of Swine Manure, Shannon L. Bartelt-Hunt

Department of Civil and Environmental Engineering: Faculty Publications

The objective of this study was to determine the effects of narrow grass hedges on the fate and transport of antimicrobials and antimicrobial resistance genes (ARGs) in runoff and in soil following the land application of swine manure slurry. Swine manure slurry was land applied to 0.75m wide by 4.0m long plots established on an Aksarben silty clay loam soil located in southeast Nebraska. Swine manure was applied at a rate to meet the 3-year nitrogen (N) requirements for corn. Swine manure was applied to plots with and without a narrow grass hedge to evaluate the effect of the hedge …

Influence Of Lateral Boundaries In Tapped Densification Of Granular Materials, Nathaniel Ching

Theses

Granular systems are widely present in the world. Soil, pharmaceutical pills, and silos filled with grain all are examples of granular systems. Experiments have long established an empirical understanding of granular systems, but an analytical understanding has been much more difficult to establish. One of the behaviors of a granular system that is well documented but poorly understood is the change in density the system undergoes when excited, also known as the densification process.

This thesis investigates the densification process of a tapped granular system using Discrete Element Model (DEM) simulations. Contact interactions in the simulations obey a well-established inelastic …

Public Private Partnership In Transit Projects, Rashmita Daschaudhuri

Theses

The government is cutting down government impediments and entering into the market. One of the outcomes has been the rise of Public-Private Partnerships (PPPs). There have been a lot of information and transaction cost problems in government institutions. These issues can be sorted and mitigated if the risk is shared with the private sector.

Until 1990, there had been a monopoly of the public sector developing transit projects. Now with the PPP concept, the transit projects are slowly moving into public private partnership agreements. This study tries to identify the various approaches of public private partnership delivery system. A few …

Effect Of Temperature On Tunneling And Quantum Efficiency In Cigs Solar Cells, Sizhan Liu

Theses

Utilizing the two-band approximation and Wentzel-Kramers-B ri l l oui n (WKB) approximation, by including the temperature-dependent effective masses and nonparabolicity effects, an investigation of the temperature dependent band-to-band tunneling process is discussed. In comparison with the parabolic approximation and non- parabolic approximation, the tunneling probability is strongly dependent on the non-parabolicity factor. The temperature dependence of the energy band gap, electron effective mass and light hole effective mass is investigated. The tunneling current density function is derived by a series representation of the incomplete gamma function with non-parabolic effect and its variation at low temperature is also investigated. When …

Analysis Of Transport Properties In A Zaz Graphene Nanoribbon Junction Using Various Dopants, Natasha Parikh

Theses

A 12 atom wide ZAZ Graphene Junction was simulated and its transport properties were analyzed. I-V curves, calculated by nonequilibrium Greens function method combined with the density functional theory under external bias, showed varying semiconducting characteristics. Further, the width of the junction also showed significant effects in the determination of the semiconducting nature. A theoretical study was performed on the semiconducting characteristics by analyzing the I-V curve and transport coefficients in the junction.