Engineering Commons^™

Image Reconstruction In Photoacoustic Computed Tomography With Acoustically Heterogeneous Media, Chao Huang

All Theses and Dissertations (ETDs)

Photoacoustic computed tomography (PACT), also known as optoacoustic or thermoacoustic tomography, is a rapidly emerging hybrid imaging modality that combines optical image contrast with ultrasound detection. The majority of currently available PACT image reconstruction algorithms are based on idealized imaging models that assume a lossless and acoustically homogeneous medium. However, in many applications of PACT these assumptions are violated and the induced photoacoustic (PA) wavefields are scattered and absorbed as they propagate to the receiving transducers. In those applications of PACT, the reconstructed images can contain significant distortions and artifacts if the inhomogeneous acoustic properties of the object are not …

Restoring Upper Extremity Mobility Through Functional Neuromuscular Stimulation Using Macro Sieve Electrodes, Erik R. Zellmer

All Theses and Dissertations (ETDs)

The last decade has seen the advent of brain computer interfaces able to extract precise motor intentions from cortical activity of human subjects. It is possible to convert captured motor intentions into movement through coordinated, artificially induced, neuromuscular stimulation using peripheral nerve interfaces. Our lab has developed and tested a new type of peripheral nerve electrode called the Macro-Sieve electrode which exhibits excellent chronic stability and recruitment selectivity. Work presented in this thesis uses computational modeling to study the interaction between Macro-Sieve electrodes and regenerated peripheral nerves. It provides a detailed understanding of how regenerated fibers, both on an individual …

Modeling And Development Of Iterative Reconstruction Algorithms In Emerging X-Ray Imaging Technologies, Jiaofeng Xu

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Many new promising X-ray-based biomedical imaging technologies have emerged over the last two decades. Five different novel X-ray based imaging technologies are discussed in this dissertation: differential phase-contrast tomography (DPCT), grating-based phase-contrast tomography (GB-PCT), spectral-CT (K-edge imaging), cone-beam computed tomography (CBCT), and in-line X-ray phase contrast (XPC) tomosynthesis. For each imaging modality, one or more specific problems prevent them being effectively or efficiently employed in clinical applications have been discussed. Firstly, to mitigate the long data-acquisition times and large radiation doses associated with use of analytic reconstruction methods in DPCT, we analyze the numerical and statistical properties of two classes …

Multiscale Modeling, Reformulation, And Efficient Simulation Of Lithium-Ion Batteries, Paul Wesley Clairday Northrop

All Theses and Dissertations (ETDs)

Lithium-ion batteries are ubiquitous in modern society, ranging from relatively low-power applications, such as cell phones, to very high demand applications such as electric vehicles and grid storage. The higher power and energy density of lithium-ion batteries compared to other forms of electrochemical energy storage makes them very popular in such a wide range of applications. In order to engineer improved battery design and develop better control schemes, it is important to understand internal and external battery behavior under a variety of possible operating conditions. This can be achieved using physical experiments, but those can be costly and time consuming, …

Design And Implementation Of Position-Encoded Microfluidic Microsphere-Trap Arrays, Xiaoxiao Xu

All Theses and Dissertations (ETDs)

Microarray devices are useful for detecting and analyzing biological targets, such as DNAs, mRNAs, proteins, etc. Applications of microarrays range from fundamental research to clinical diagnostics and drug discovery. In this dissertation, we consider a microsphere array device with predetermined positions of the microspheres. The microspheres are conjugate on their surfaces with molecular probes to capture the targets, and the targets are identified by the microspheres' positions. We implement the microsphere arrays by employing microfluidic technology and a hydrodynamic trapping mechanism. We call our device microfluidic microsphere-trap arrays. To fully realize the potential of the device in biomedical applications, we …

Power System State Estimation And Renewable Energy Optimization In Smart Grids, Peng Yang

All Theses and Dissertations (ETDs)

The future smart grid will benefit from real-time monitoring, automated outage management, increased renewable energy penetration, and enhanced consumer involvement. Among the many research areas related to smart grids, this dissertation will focus on two important topics: power system state estimation using phasor measurement units (PMUs), and optimization for renewable energy integration.

In the first topic, we consider power system state estimation using PMUs, when phase angle mismatch exists in the measurements. In particular, we build a measurement model that takes into account the measurement phase angle mismatch. We then propose algorithms to increase state estimation accuracy by taking into …

Optimization Of Layered Battery Cathode Materials Synthesized Via Spray Pyrolysis, Miklos Lengyel

All Theses and Dissertations (ETDs)

Rapid advancements of techniques for the synthesis of Li-ion battery materials are critically needed to address the requirement of a clean and efficient transportation sector. The current research serves this goal by developing an approach to producing layered cathode materials with superior electrochemical performance for electric vehicles (EVs). Current widespread application of EVs is primarily limited by their short range and their high price, which is primarily driven by the cost of the battery pack. The cost of the battery pack is driven by the cost of the cathode material that empowers it.

Novel, high throughput and inexpensive synthesis methods …

Submicron-Resolution Photoacoustic Microscopy Of Endogenous Light-Absorbing Biomolecules, Chi Zhang

All Theses and Dissertations (ETDs)

Photoacoustic imaging in biomedicine has the unique advantage of probing endogenous light absorbers at various length scales with a 100% relative sensitivity. Among the several modalities of photoacoustic imaging, optical-resolution photoacoustic microscopy (OR-PAM) can achieve high spatial resolution, on the order of optical wavelength, at <1 mm depth in biological tissue (the optical ballistic regime). OR-PAM has been applied successfully to structural and functional imaging of blood vasculature and red blood cells in vivo. Any molecules which absorb sufficient light at certain wavelengths can potentially be imaged by PAM. Compared with pure optical imaging, which typically targets fluorescent markers, label-free PAM avoids the major concerns that the fluorescent labeling probes may disturb the function of biomolecules and may have an insufficient density. This dissertation aims to advance label-free OR-PAM to the subcellular scale.

The first part of this dissertation describes the technological advancement of PAM yielding high spatial resolution in 3D. The lateral resolution was improved by using optical objectives with high numerical apertures for optical focusing. The axial resolution was improved by using broadband ultrasonic transducers for ultrasound detection. We achieved 220 nm lateral resolution in transmission …

Thrombin-Inhibiting Perfluorocarbon Nanoparticles: A New Class Of Therapeutic For Acute Thrombosis Treatment And Diagnosis, Jacob Wheatley Myerson

All Theses and Dissertations (ETDs)

Optimization of the mediation of acute thrombi remains a significant research challenge in the treatment of emergency conditions including heart attack and ischemic stroke. We have demonstrated that a nanoparticle carrying potent direct thrombin inhibitors can advance the treatment of acute thrombosis arising from various cardiovascular pathologies. The thrombin-inhibiting nanoparticles presented herein are designed to focus the antithrombotic impact of direct thrombin inhibitors at the site of thrombus formation and to provide imaging contrast to highlight the formation or the abatement and eventual disintegration of the thrombus.

Perfluorocarbon nanoparticles were functionalized by covalent addition of PPACK or bivalirudin to carboxy-PEG …

Elucidation Of Emergent Regional Mechanisms Of Heart Muscle Dysfunction In The Mouse Model Of Duchenne Muscular Dystrophy, Ya-Jian Cheng

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Cardiac dysfunction is a primary cause of mortality in Duchenne Muscular Dystrophy (DMD), potentially related to elevated cytosolic calcium. However, the regional versus global functional consequences of cellular calcium mishandling have not been defined in the whole heart. Here, we elucidate, for the first time, loci- and age-dependencies between calcium mishandling and myocardial sheet function as a manifestation of dystrophin-deficient cardiomyopathy. We also map calcium transients to illustrate the regional dependence of ion flux disturbances in the dystrophin-deficient (mdx) mouse heart. Furthermore, we elucidate abnormalities in autophagic processes that can be corrected with nanoparticle therapeutics delivering rapamycin to heart tissues …

Optimization Of Wind Turbine Airfoils/Blades And Wind Farm Layouts, Xiaomin Chen

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Shape optimization is widely used in the design of wind turbine blades. In this dissertation, a numerical optimization method called Genetic Algorithm (GA) is applied to address the shape optimization of wind turbine airfoils and blades. In recent years, the airfoil sections with blunt trailing edge (called flatback airfoils) have been proposed for the inboard regions of large wind-turbine blades because they provide several structural and aerodynamic performance advantages. The FX, DU and NACA 64 series airfoils are thick airfoils widely used for wind turbine blade application. They have several advantages in meeting the intrinsic requirements for wind turbines in …

Systems Metabolic Engineering Of Microbial Cell Factories For The Synthesis Of Value-Added Chemicals, Arul Mozhy Varman

All Theses and Dissertations (ETDs)

Microbial cell factories offer us an excellent opportunity for the conversion of many different cheaply available raw materials into valuable chemicals. Systems metabolic engineering aims at developing rational strategies for the engineering of microbial hosts by providing global level information of a cell. This dissertation focuses on metabolic engineering, bioprocess modeling and pathway analysis, to develop robust microbial cell factories for the synthesis of value-added chemicals. The following research tasks were completed in this regard.

First, statistical models were developed for the prediction of product yields in engineered microbial cell factories - Saccharomyces cerevisiae and Escherichia coli: Chapter 2). A …

Intraurban Variability Of Ambient Particulate Matter, Varun Yadav

All Theses and Dissertations (ETDs)

An understanding of spatial and temporal variability in ambient particulate matter: PM) is important for effective air quality management and for assessing potential exposure misclassification in epidemiological and exposure studies used to support health-based standards. Spatiotemporal variability of PM in urban areas can be influenced by many factors, such as local sources of primary PM; source locations and their emission profiles; topographic barriers; meteorological patterns; behavior of semi-volatile components; and measurement errors. Intraurban variability is often gauged by conducting measurements at a network of monitoring stations across the region of interest. While certain statistical metrics are commonly used and interpreted …

Emg-Emg Coherence Analysis Of Elbow And Shoulder Muscles, Manu Stephen

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Motor coordination can be described by the activation of a few intermuscular coordination patterns, or muscle synergies. Muscle synergy can be defined as a relatively fixed pattern of activation across a set of muscles. The neural mechanisms underlying muscle synergies remain to be fairly unknown. Through a muscle synergy study [13], co-activation in muscle pairs was discovered through a non-negative matrix factorization: NMF) analysis. In order to evaluate the same muscles under the frequency domain, coherence analysis: a correlational method) was used. Additionally, a comparison can be made to determine if the resulting muscle pairs overlap with the muscle pairs …

Oxy-Combustion Of High Water Content Fuels, Fei Yi

All Theses and Dissertations (ETDs)

As the issues of global warming and the energy crisis arouse extensive concern, more and more research is focused on maximizing energy efficiency and capturing CO2 in power generation. To achieve this, in this research, we propose an unconventional concept of combustion - direct combustion of high water content fuels. Due to the high water content in the fuels, they may not burn under air-fired conditions. Therefore, oxy-combustion is applied. Three applications of this concept in power generation are proposed - direct steam generation for the turbine cycle, staged oxy-combustion with zero flue gas recycle, and oxy-combustion in a low …

Ecog Correlates Of Visuomotor Transformation, Neural Plasticity, And Application To A Force-Based Brain Computer Interface, Jordan John Williams

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Electrocorticography: ECoG) has gained increased notoriety over the past decade as a possible recording modality for Brain-Computer Interface: BCI) applications that offers a balance of minimal invasiveness to the patient in addition to robust spectral information over time. More recently, the scale of ECoG devices has begun to shrink to the order of micrometer diameter contacts and millimeter spacings with the intent of extracting more independent signals for BCI control within less cortical real-estate. However, most control signals to date, whether within the field of ECoG or any of the more seasoned recording techniques, have translated their control signals to …

Multiple-Target Tracking In Complex Scenarios, Srinivas Phani Kumar Chavali

All Theses and Dissertations (ETDs)

In this dissertation, we develop computationally efficient algorithms for multiple-target tracking: MTT) in complex scenarios. For each of these scenarios, we develop measurement and state-space models, and then exploit the structure in these models to propose efficient tracking algorithms. In addition, we address design issues such as sensor selection and resource allocation.

First, we consider MTT when the targets themselves are moving in a

time-varying multipath environment. We develop a sparse-measurement model that allows us to exploit the inherent joint delay-Doppler diversity offered by the environment. We then reformulate the problem of MTT as a

block-support recovery problem using the …

Coupling Of The Biogeochemical Cycles Of Uranium And Manganese: Implications For The Fate And Transport Of Uranium In Subsurface Environments, Zimeng Wang

All Theses and Dissertations (ETDs)

Organic electron donor stimulated microbial reduction of U(VI) to U(IV) has been proposed as a strategy for the in situ immobilization of uranium contamination in the subsurface. The success of the bioremediation of uranium relies on the stability of the reduced U(IV) species: e.g., UO2) with respect to reoxidation and/or remobilization under groundwater conditions. Manganese is present at appreciable concentrations at several uranium-contaminated sites, and the redox cycling of manganese may significantly impact uranium's fate and transport. The biogeochemical coupling of uranium and manganese involves multiple interaction pathways that occur in the aqueous phase as well as at solid-water interfaces. …

Wireless Cyber-Physical Simulator And Case Studies On Structural Control, Bo Li

All Theses and Dissertations (ETDs)

No abstract provided.

Numerical Simulation Of Separated And Secondary Flows In Diffusing S-Ducts For Air Breathing Propulsion, Colin James Fiola

All Theses and Dissertations (ETDs)

No abstract provided.

End-To-End Delay Analysis For Wireless Control Networks Under Edf Scheduling, Chengjie Wu

All Theses and Dissertations (ETDs)

No abstract provided.

Difficulties And Opportunities In Building Resilient Clinical Monitoring Systems With Wireless Sensor Networks, Rahav Dor

All Theses and Dissertations (ETDs)

No abstract provided.

High-Resolution Low-Noise Polarization Imaging Sensor For Astronomical Applications, Radoslav Marinov

All Theses and Dissertations (ETDs)

Polarization imaging is useful to the field of astronomy because the polarization state caused by reflections, scattering events, and magnetic fields can be used to infer properties such as shape and index of refraction about celestial bodies. This work presents a low-noise high-resolution polarization imaging sensor consisting of a CCD imager overlaid with a nanowire linear polarizer filter array of four different orientations: 0°, 45°, 90°, and 135°) matched to the pixel pitch. Fabrication details and experimental setup for characterization are discussed. The performance of the sensor is assessed over a range of polarization states, light intensities, wavelengths, and incident …

Ideal Optimum Performance Of Propellers, Lifting Rotors And Wind Turbines, Ramin Modarres

All Theses and Dissertations (ETDs)

No abstract provided.

Delivering Consistent Network Performance In Multi-Tenant Data Centers, Mart Albert Haitjema

All Theses and Dissertations (ETDs)

Data centers are growing rapidly in size and have recently begun acquiring a new role as cloud hosting platforms, allowing outside developers to deploy their own applications on large scales. As a result, today's data centers are multi-tenant environments that host an increasingly diverse set of applications, many of which have very demanding networking requirements. This has prompted research into new data center architectures that offer increased capacity by using topologies that introduce multiple paths between servers. To achieve consistent network performance in these networks, traffic must be effectively load balanced among the available paths. In addition, some form of …

Numerical Simulation And Optimization Of Co2 Sequestration In Saline Aquifers, Zheming Zhang

All Theses and Dissertations (ETDs)

With heightened concerns on CO2 emissions from pulverized-coal power plants, there has been major emphasis in recent years on the development of safe and economical Geological Carbon Sequestration: GCS) technology. Although among one of the most promising technologies to address the problem of anthropogenic global-warming due to CO2 emissions, the detailed mechanisms of GCS are not well-understood. As a result, there remain many uncertainties in determining the sequestration capacity of the formation/reservoir and the safety of sequestered CO2 due to leakage. These uncertainties arise due to lack of information about the detailed interior geometry of the formation and the heterogeneity …

Optimization Of Induced-Power From Dynamic Inflow Theory With Realistic Constraints, Chad File

All Theses and Dissertations (ETDs)

Finite-state induced-inflow theory is used to develop an analytic formulation for general performance of the lifting rotor with arbitrary loading. The theory incorporates conventional blade-element theory for blade lift and provides the integrated loads and the induced-power of the rotor in terms of an arbitrary number of rotor controls such as conventional collective and cyclic pitch as well as higher harmonic radial and azimuthal pitch. The theory provides the basis for a classical quadratic optimization with realistic constraints that is applied to determine minimum induced-power for a variety of available control combinations, rotor trim constraints, and operating conditions. The findings …

Development Of Optimization Models For The Set Behavior And Compressive Strength Of Sodium Activated Geopolymer Pastes, Brian Albert Fillenwarth

All Theses and Dissertations (ETDs)

As large countries such as China begin to industrialize and concerns about global warming continue to grow, there is an increasing need for more environmentally friendly building materials. One promising material known as a geopolymer can be used as a portland cement replacement and in this capacity emits around 67% less carbon dioxide. In addition to potentially reducing carbon emissions, geopolymers can be synthesized with many industrial waste products such as fly ash.

Although the benefits of geopolymers are substantial, there are a few difficulties with designing geopolymer mixes which have hindered widespread commercialization of the material. One such difficulty …

Capacity Fade Analysis And Model Based Optimization Of Lithium-Ion Batteries, Venkatasailanathan Ramadesigan

All Theses and Dissertations (ETDs)

Electrochemical power sources have had significant improvements in design, economy, and operating range and are expected to play a vital role in the future in a wide range of applications. The lithium-ion battery is an ideal candidate for a wide variety of applications due to its high energy/power density and operating voltage. Some limitations of existing lithium-ion battery technology include underutilization, stress-induced material damage, capacity fade, and the potential for thermal runaway. This dissertation contributes to the efforts in the modeling, simulation and optimization of lithium-ion batteries and their use in the design of better batteries for the future. While …

A Rigorous Solution For Finite-State Inflow Throughout The Flowfield, Zhongyang Fei

All Theses and Dissertations (ETDs)

In this research, the Hseih/Duffy model is extended to all three velocity components of inflow across the rotor disk in a mathematically rigorous way so that it can be used to calculate the inflow below the rotor disk plane. This establishes a complete dynamic inflow model for the entire flow field with finite state method. The derivation is for the case of general skewed angle. The cost of the new method is that one needs to compute the co-states of the inflow equations in the upper hemisphere along with the normal states. Numerical comparisons with exact solutions for the z-component …