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Title: FLEXIBLE, COMPACT, AND HIGH-POWER-COMPATIBLE PACKAGING OF MICROWAVE AND MILLIMETER-WAVE ELECTRONICS
Creator: Konstantinou, Xenofon
Date: 2022
Collection: Electronic Theses & Dissertations
Description: This dissertation demonstrates packaging strategies for microwave and millimeter-wave (mmwave) system integration, realized via additive manufacturing (AM), and specifically aerosol jet printing (AJP), that are mm-wave-capable, flexible, and compatible with high-power applications. These strategies build upon the concept of chip-first packaging that has been previously demonstrated via AJP. Such packaging approaches address the limitations of conventional systems-onpackage (SoP)/systems-in...
Show moreThis dissertation demonstrates packaging strategies for microwave and millimeter-wave (mmwave) system integration, realized via additive manufacturing (AM), and specifically aerosol jet printing (AJP), that are mm-wave-capable, flexible, and compatible with high-power applications. These strategies build upon the concept of chip-first packaging that has been previously demonstrated via AJP. Such packaging approaches address the limitations of conventional systems-onpackage (SoP)/systems-in-package (SiP) strategies and aim for heterogeneous integration and high functional density. The final SiP/SoP strategy demonstrated in this dissertation achieves improved performance comparing to previously demonstrated packages and interconnects via AM, and additionally demonstrates more material flexibility, improved interconnect reliability, incorporation of diamond platforms as heatsinks for high-power operation, and high-power performance.The first step in the dissertation is to explore the high-power and temperature capabilities of diamond via basic high-power RF devices. Then, the compatibility of diamond and AJP is investigated by realizing RF components printed on diamond dielectric substrates. Thereafter, the state of the art in additively manufactured interconnects and components is advanced via the demonstration of compact resonant structures at mm-wave, ultra-wideband mm-wave interconnects on non-planar structures, as well as components at near-THz frequencies, all manufactured fully via AJP. Then, AJP-enabled SiP/SoP packaging strategies for mm-wave system integration are laid out and then used for the realization of RF front-end modules. Finally, these strategies are adapted to incorporate diamond platforms, with the final packages demonstrating high RF power performance.
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Title: Fiber-optic sensors based on fiber bragg gratings for dynamic strain measurement
Creator: Zhu, Yupeng
Date: 2020
Collection: Electronic Theses & Dissertations
Description: This dissertation investigates how to measure dynamic strain including quasi-static strain, vibration, acoustic emission, and ultrasonic waves with fiber Bragg grating based optical fiber sensors. Fiber optic sensors are inherently immune to electromagnetic interference, light weight, small size, corrosion resistance, and capable of multiplexing. With narrow linewidth tunable lasers, the strain induced spectral shift of the Bragg wavelength of the sensor can be demodulated. However, the...
Show moreThis dissertation investigates how to measure dynamic strain including quasi-static strain, vibration, acoustic emission, and ultrasonic waves with fiber Bragg grating based optical fiber sensors. Fiber optic sensors are inherently immune to electromagnetic interference, light weight, small size, corrosion resistance, and capable of multiplexing. With narrow linewidth tunable lasers, the strain induced spectral shift of the Bragg wavelength of the sensor can be demodulated. However, the spectrum of the uniform fiber Bragg grating can not satisfy the sensitivity, resolution, and dynamic range requirements. To address these challenges, we propose and demonstrate a sensor structure based on chirped fiber Bragg gratings combined with Fabry-Perot cavity. Taking advantage of large bandwidth provided by the chirped fiber Bragg grating and the narrow resonance peaks formed by the Fabry-Perot cavity, it can simultaneously achieve high resolution, high sensitivity, and large dynamic range measurement.The second chapter provides the theoretical analysis and numerical simulation on the spectra of chirped fiber Bragg gratings and Fabry-Perot cavities. Based on such context, we are motivated to propose a dynamic strain measurement scenario which take advantage of both high resolution and large dynamic range of the sensor. Due to the different and unique spectral intervals of the notches in the wavelength bandwidth used for measurement, the spectral notches can be unambiguously recognized in each spectral frame without the need for fringe counting. Using this principle, we demonstrated high-resolution and absolute static and dynamic strain measurement. In chapter three, we study the acoustic emission detection with the proposed sensor based on high finesse short cavity structure and explore the potential of using the narrow resonance peak as the laser locking source to reduce the laser noise while functions as ultrasound sensor. Additionally, since the Bragg wavelength is highly related to the polarization, birefringence causes polarization dependent center-wavelength shift. We propose a 90-degree rotation method for grating fabrication in the UV laser beam side exposure technique to reduce the birefringence. Therefore the sensor is insensitive to the polarization state of the laser, the ultrasound detection system can be simplified by omitting the polarization controller. Chapter four expands our work on ultrasonic sensor by using coiled fiber with low-finesse Fabry-Perot interferometer formed by two chirped fiber Bragg gratings. Our work has successfully demonstrated a strain and temperature insensitive fiber-optic ultrasonic detection by combining the coil structure, wide spectral range, and quadrature demodulation. The ultrasonic sensing scheme is immune to the laser wavelength drift, therefore no wavelength locking mechanism is needed. Future work will continue on exploring new design of the sensor structure and optimizing the measurement system to further improve the feasibility while reduce the overall cost.
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Title: High Accuracy Wireless Ranging For Phase Alignment In Distributed Microwave Beamforming Arrays
Creator: Ellison, Sean Michael
Date: 2020
Collection: Electronic Theses & Dissertations
Description: In recent years, there has been an increasing interest in distributed antenna arrays due to their potential to provide improvements in performance, scalability, robustness, and cost over classic phased antenna arrays. Distributed arrays synthesize a large aperture using small, low-cost, and low-power devices, supporting improvements that would otherwise be too costly or bulky to achieve in a single system. Such arrays also have the flexibility to be scaled by adding or removing elements from...
Show moreIn recent years, there has been an increasing interest in distributed antenna arrays due to their potential to provide improvements in performance, scalability, robustness, and cost over classic phased antenna arrays. Distributed arrays synthesize a large aperture using small, low-cost, and low-power devices, supporting improvements that would otherwise be too costly or bulky to achieve in a single system. Such arrays also have the flexibility to be scaled by adding or removing elements from the array, depending on the application at hand. Within distributed antenna arrays, there are generally two classes that are considered: incoherent distributed arrays, where little or no coordination is performed between nodes in the array, yielding a collection of individual wireless systems; and coherent distributed arrays, where element coordination is performed at the level of the radio frequency phase. While incoherent arrays are easier to implement, their improvements, such as gain and signal-to-noise ratio, generally scale only as the square-root of the number of elements, yielding diminishing returns. Coherent arrays achieve sensitivity improvements directly proportional to the number of elements in the array, yielding significant improvements as the array scales. However, distributed coherence requires significantly more coordination between nodes. The electrical states that need to be aligned to enable coherent beamforming include: each device's internal clock frequencies; relative timing of information symbols; and alignment of the beamforming phase. In general, there are two methods to achieve alignment: closed-loop and open-loop. Closed loop is only feasible to applications that have reliable feedback from the receive location, such as communications systems. Open-loop requires the nodes to coordinate without feedback, but opens the application space to instances where there is no feedback from the destination such as radar and remote sensing.In this work, I focus on the alignment of the phase of the beamforming signals in open-loop coherent distributed antenna arrays. I present a distributed antenna array supporting open-loop distributed beamforming at 1.5 GHz. Based on a scalable, high-accuracy internode ranging technique, I demonstrate open-loop beamforming experiments using three transmitting nodes. To support distributed beamforming without feedback from the destination, the relative positions of the nodes in the distributed array must be known with accuracies below $\lambda/15$ of the beamforming carrier frequency to ensure that the array maintains at least 90% coherent beamforming gain at the receive location. For operations at microwave frequencies, this leads to range estimation accuracies of centimeters or less. I present scalable, high-accuracy waveforms and new approaches to refine range measurements to significantly improve the estimation accuracy. Using one of the designed waveforms with a three-node array, I demonstrate high-accuracy ranging simultaneously between multiple nodes, from which phase corrections on two secondary nodes are implemented to maintain beamforming with the primary node, thereby supporting open-loop distributed beamforming. Upon movement of the nodes, the range estimation is used to dynamically update the phase correction, maintaining beamforming as the nodes move. I show the first open-loop distributed beamforming at 1.5 GHz with two-node and three-node arrays, demonstrating the ability to implement and maintain phase-based beamforming without feedback from the destination.
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Title: High-Speed Millimeter-Wave Active Incoherent Fourier Domain Imaging
Creator: Vakalis, Stavros
Date: 2022
Collection: Electronic Theses & Dissertations
Description: Millimeter-wave imaging is used in applications such as security screening, remote sensing, medical imaging, and non-destructive testing due to the good penetration characteristics of millimeter-wave radiation which can provide "see-through" capabilities. Electromagnetic signals in the frequency range of 30 - 300 GHz can penetrate easily through materials like clothing, fog, and smoke, and at the same time provide image reconstruction with fine spatial resolution. Millimeter-wave imaging is...
Show moreMillimeter-wave imaging is used in applications such as security screening, remote sensing, medical imaging, and non-destructive testing due to the good penetration characteristics of millimeter-wave radiation which can provide "see-through" capabilities. Electromagnetic signals in the frequency range of 30 - 300 GHz can penetrate easily through materials like clothing, fog, and smoke, and at the same time provide image reconstruction with fine spatial resolution. Millimeter-wave imaging is typically implemented by means of mechanical or electrical scanning which requires long data acquisition times or a large number of active components. Computational imaging can reduce both the data acquisition time and the number of active components, but this comes at the cost of heavy computational loads, which makes real-time operation challenging. Passive millimeter-wave imaging systems that capture thermal signals and operate similarly to optical cameras, are very costly because they need to employ highly sensitive receivers due to thermal radiation being extremely low power at millimeter-wave frequencies. A paradigm shift is needed in order to advance the current imaging modalities in millimeter-wave frequencies.In this dissertation, I present a newly developed millimeter-wave imaging technique called active incoherent millimeter-wave (AIM) imaging which combines the benefits of active and passive millimeter-wave imaging. This approach combines the high signal-to-noise ratio capabilities of active millimeter-wave imaging systems with the fast image formation potential of passive millimeter-wave imaging systems. The combination is achieved by illuminating the scene with multiple spatially distributed noise transmitters that mimic the randomness of thermal radiation. Because the concept of incoherent noise illumination has not been investigated thoroughly in the literature of millimeter-wave imaging, I discuss design considerations for creating a space-time incoherent transmitter and novel measurements for characterizing space-time incoherence. Starting from my earlier work in microwave frequencies, I present the system design and calibration approach, along with an experimental demonstration of a millimeter-wave active incoherent digital array. The array is capable of generating millimeter-wave video at very high frame rates, and millimeter-wave imaging results of 652 frames per second of a sphere moving in a pendulum motion are included. The scenario of using the stray reflections from a small set of communications transmitters is also examined and I present results using WiFi and fifth-generation (5G) communications signals. I also expand interferometric imaging to three dimensions using a novel pulse modulation as an envelope on the noise signals to provide differentiation along the range dimension. Prior to this work, three-dimensional interferometric millimeter-wave imaging had only been implemented in the near-field region or using three-dimensional volumetric arrays, which pose significant size and volume concerns. A new algorithm for three-dimensional interferometric image formation is presented along with simulated results and experimental measurements.
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Title: High-performance chemiresistor instrumentation circuit for micro gas chromatograph
Creator: Mu, Xiaoyi
Date: 2010
Collection: Electronic Theses & Dissertations
Description: Gas chromatography is a technology that permits detection, classification and quantification of gas and vapor mixtures, showing wide application in environmental monitoring, military surveillance, and healthcare diagnostics. Miniaturization of the gas chromatograph to a portable platform would bring significant benefits in terms of speed, sensitivity, and cost. Such a micro gas chromatograph (uGC) would open many new sensing applications that cannot be addressed by existing instruments. This...
Show moreGas chromatography is a technology that permits detection, classification and quantification of gas and vapor mixtures, showing wide application in environmental monitoring, military surveillance, and healthcare diagnostics. Miniaturization of the gas chromatograph to a portable platform would bring significant benefits in terms of speed, sensitivity, and cost. Such a micro gas chromatograph (uGC) would open many new sensing applications that cannot be addressed by existing instruments. This thesis seeks to overcome the challenges and limitations in instrumentation circuits for a uGC detector utilizing thiolate-monolayer-protected gold nanoparticles (MPN) chemiresistor (CR) arrays. Two approaches for CR array instrumentation were explored. First, a CMOS instrumentation circuit using DC techniques was designed and tested. The 8-channel DC chip achieves a resolution better than 125ppm over a very wide baseline resistance range and 120dB dynamic range. Second, an AC instrumentation circuit was developed to overcome the noise limitations inherent to the DC circuit. In addition, a methodology for integrating CR arrays directly onto the surface of the instrumentation chip was studied and implemented to further miniaturize the uGC and maximize resolution. The results of this research lay a solid foundation for future realization of high sensitivity uGCs.
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Title: INTEGRATED MICROSYSTEM TECHNOLOGIES FOR CONTINUOUS PERSONAL MONITORING OF AIRBORNE POLLUTANT EXPOSURES
Creator: Yin, Heyu
Date: 2021
Collection: Electronic Theses & Dissertations
Description: ABSTRACTINTEGRATED MICROSYSTEM TECHNOLOGIES FOR CONTINUOUS PERSONAL MONITORING OF AIRBORNE POLLUTANT EXPOSURESBy Heyu Yin Exposure to airborne pollutants, including gaseous toxins and particulate matter (PM), threaten human health and are of growing world concern. Unfortunately, the specific mechanisms behind medical conditions induced by air pollutants, as well as the socioeconomic demographics that underpin these conditions, are poorly understood. This is due, in large part, to a lack of...
Show moreABSTRACTINTEGRATED MICROSYSTEM TECHNOLOGIES FOR CONTINUOUS PERSONAL MONITORING OF AIRBORNE POLLUTANT EXPOSURESBy Heyu Yin Exposure to airborne pollutants, including gaseous toxins and particulate matter (PM), threaten human health and are of growing world concern. Unfortunately, the specific mechanisms behind medical conditions induced by air pollutants, as well as the socioeconomic demographics that underpin these conditions, are poorly understood. This is due, in large part, to a lack of accurate data detailing exposure profiles of individuals who suffer from acute and chronic health conditions. Air pollution levels and the activities of individuals exhibit a large degree of spatial and temporal variation, which both challenge the assessment of personal exposures. Moreover, health impacts vary significantly with chemical composition and particle size of pollutants, which further complicates effective monitoring. Utilizing a combination of microfabrication, microfluidics and electrochemical sensing technologies, this thesis research explored a microsystem solution to these challenges that can achieve high spatial resolution by providing a compact, mobile/wearable monitoring device and can achieve high temporal resolution by enabling continuous collection of personal exposure data. To create a compact monitor for multiple gaseous air pollutants, unique microfabrication procedures and electrochemical techniques were established, enabling a gas sensor array that features room temperature ionic liquid electrolyte and achieves high reliability and repeatability. In addition, a novel PM monitoring platform that uniquely employs microfluidics to achieve real-time continuous measurement was introduced, and key component technologies were developed. First, to measure PM concentrations within a compact microfluidic device, an electrochemical quantification method based on the ionic electret effect was employed for the first time using microfabricated planar electrodes and a microelectronic instrumentation module. Second, to permit real-time analysis of PM across a wide range of particle diameters, multiple generations of a microfluidic size fractionation component were developed. The first microfabricated size fractionation device realized the deterministic lateral displacement (DLD) method with a critical diameter of 2.5 μm and was successfully demonstrated to separate 10 μm and 1 μm particles with around 100% efficiency. The next size fractionation design aimed to provide multi-size separation over a wide dynamic range (~1000) of particle sizes that impact human health, down to ultrafine (nanoscale) PM. The resulting externally balanced cascade DLD concept was implemented within a mathematic model that predicts size fractionation of PM, from 10 μm to 0.01 μm, can be achieved with a minimum total device length of ~41mm using a four-section cascade. Finally, to further miniaturize the size separation device toward a monolithic implementation, an internally balanced cascade DLD design concept that can omit extra inputs and outputs was introduced and thoroughly analyzed using computational fluid dynamics simulations. The combined results of this research overcome many challenges that currently impede the desperately needed realization of personal airborne pollutant monitors offering wearable, real-time and continuous operation for unprecedented spatial and temporal resolution.
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Title: INVESTIGATION OF SINGLE CRYSTAL DIAMOND FOR SWIFT HEAVY ION BEAM DETECTORS AND STUDY OF DIAMOND GROWTH FOR IMPROVEMENT OF DIAMOND MATERIAL FOR DETECTORS
Creator: Bhattacharya, Ayan
Date: 2018
Collection: Electronic Theses & Dissertations
Description: Diamond is a material with outstanding mechanical, electrical and optical properties. Single crystal diamond has a large bandgap (~ 5.47 eV), large atomic displacement energy (~ 43eV), high electric breakdown field (107 V cm-1) and high thermal conductivity at room temperature. All these superior properties make diamond inherently a superb radiation tolerant material for harsh radiation environments. In this study, single crystal diamond (scd) substrates grown at Michigan State University ...
Show moreDiamond is a material with outstanding mechanical, electrical and optical properties. Single crystal diamond has a large bandgap (~ 5.47 eV), large atomic displacement energy (~ 43eV), high electric breakdown field (107 V cm-1) and high thermal conductivity at room temperature. All these superior properties make diamond inherently a superb radiation tolerant material for harsh radiation environments. In this study, single crystal diamond (scd) substrates grown at Michigan State University (MSU) by microwave plasma-assisted chemical vapor deposition (MPACVD) are tested to develop detectors for swift heavy ion beam. Prior to beam irradiation, the material properties of the diamond were characterized by UV-VIS spectroscopy and FTIR (Fourier Transform Infrared Spectroscopy). After fabrication of detectors, their performance were tested by irradiating with swift heavy ion (SHI) beams in the range of 100-150 MeV/u at the National Superconducting Cyclotron Laboratory (NSCL) at MSU. In addition to MSU grown samples, commercial electronic grade samples (Microwave Enterprises Ltd.) were also investigated under the same radiation environment. Post irradiation, samples ware characterized by the transient current technique (TCT) to understand how charge transport properties get affected by the beam irradiation. The charge collection efficiency (CCE) and the lifetime of the holes and electrons created were studied. A completely non-irradiated commercially available electronic grade diamond was also tested in the same testing configuration to generate a reference. Beam irradiated samples were also characterized by X-ray diffraction and Raman spectroscopy to characterize for any structural damage. The overall characterizations mostly confirmed a deterioration of charge transport properties. However, any evidence of substantial structural damage by the irradiation could not be found. One relevant observation was that the MSU lab grown diamond had a shorter carrier lifetime primarily due to more nitrogen impurities present in the grown diamond. Next, to improve charge transport performance of MSU lab grown diamond substrates for electronic applications, single crystal diamond was deposited in a low nitrogen environment to grow thick layers (≥ 200 μm). In general, epitaxial growth on surface close to the (001) crystallographic plane at a low nitrogen environment often suffers from defects forming on the surface. Such defects arise from dislocations (already present in the substrate), twining during the growth process. A possible solution to this issue is to grow samples on misoriented substrates (i.e. on surfaces that are slightly tilted from the (001) plane). The resulting surface profile largely depends on the growth condition (i.e. temperature, pressure, methane concentration), as well as the substrate misorientation angle. The deposition on a misoriented surface happens with a step flow growth process. It is found in research literature that impurities present in the deposition gas generally tend to concentrate at steps more than on terrace. Hence the spatial size of the step height and terrace width distribution produced as a result of misorientation angle variation is important for the quality of the deposited diamond. A detailed study of the distribution of step height and terrace width with respect to misorientation angle for thick layers (~ 200 μm) was performed. The step height and terrace width distributions can help decide the selection of offcut angle, doping concentration and growth layer thickness, which otherwise may create localized and non-uniform distribution of impurities and non-uniform breakdown electric fields.
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Title: Interleaved source coding for packet video over erasure channels
Creator: Lee, Jin Young
Date: 2008
Collection: Electronic Theses & Dissertations

Title: LOW-TEMPERATURE PROCESSING FOR AEROSOL-JET PRINTED SILVER CONTACTS
Creator: Abu-Ageel, Atef M.
Date: 2021
Collection: Electronic Theses & Dissertations
Description: After 3D printing was commercialized in the early 1990s, the industry experienced huge interest from tool developers who capitalized on additive manufacturing and enjoyed noticeable growth as a result. Multiple industries are weighing the benefits of 3D printing and what it can offer in terms of savings in operations cost and also adding new features to their customers. It is predicted that the global 3D market in terms of equipment, materials, software, and services will reach $31 billion by...
Show moreAfter 3D printing was commercialized in the early 1990s, the industry experienced huge interest from tool developers who capitalized on additive manufacturing and enjoyed noticeable growth as a result. Multiple industries are weighing the benefits of 3D printing and what it can offer in terms of savings in operations cost and also adding new features to their customers. It is predicted that the global 3D market in terms of equipment, materials, software, and services will reach $31 billion by 2030 according to industry analysts.Electronic devices’ major fabrication element is the creation of conductive structures and interconnects utilizing additive or subtractive processes. Most electronic systems are fabricated using photolithography, which is a subtractive process that is frequently complex and time-consuming using expensive clean facilities. Furthermore, this process generates large amounts of harmful waste in most cases. 3D inkjet printing techniques for the purpose of fabricating electronic devices are less expensive compared to photolithography. 3D printing has recently begun to be attractive as a potential technology to supersede lithographic processes for lower-volume and rapidly emerging areas. For example, conductive silver inks cover a wide range of markets, including organic light emitting diodes, photovoltaics, antennas, ceramic capacitors, radio frequency identification, medical devices, and many more. The high conductivity of metals printed using materials like silver or copper inks gives the flexibility to print thinner and longer circuit trace lines on complex geometries without compromising overall resistivity values, which can result in major cost savings for rapid prototyping and low-volume situations. In this work, silver ink is used to form a contact material that could be used as an ohmic metal contact material realized at low processing temperatures for soft electronic material applications such as organic light emitting diodes and transparent photovoltaics. The silver ink is printed using Aerosol Jet Printing technology and cured using an optical heating pulse system and can result in useful metal contacts without exceeding 35°C. The proposed technique does not require a cleanroom environment. This makes the proposed method of printing the contacts in ambient conditions cost-efficient and easy to implement without significantly sacrificing performance when higher temperature processing cannot be used.
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Title: MODELING OF NANOSCALE ELECTRICAL JUNCTIONS AND ELECTRICAL CONTACTS
Creator: Banerjee, Sneha
Date: 2021
Collection: Electronic Theses & Dissertations
Description: Nano-scale electrical contacts are essential for next generation electronics. Based on the materials of the contact members and the interfacial layers, these junctions can be of ohmic, Schottky or tunneling type. Nonuniform current distribution and current crowding across electrical contacts lead to nonuniform heat deposition, formation of local thermal hotspots, aggravation of electromigration, and in the worst scenario, lead to thermal runaway and breakdown of the device. Contact resistance...
Show moreNano-scale electrical contacts are essential for next generation electronics. Based on the materials of the contact members and the interfacial layers, these junctions can be of ohmic, Schottky or tunneling type. Nonuniform current distribution and current crowding across electrical contacts lead to nonuniform heat deposition, formation of local thermal hotspots, aggravation of electromigration, and in the worst scenario, lead to thermal runaway and breakdown of the device. Contact resistance, on the other hand, severely restricts the current flow, and affects the overall device properties. Devices based on thin film junctions, nanotubes or nanowires, and two-dimensional (2D) materials are especially sensitive to the current transport at electrical contacts, due to their reduced dimensions and increased geometrical confinement for the current flow. The goal of this thesis is to develop theoretical models to understand, improve, and control current transport and to reduce contact resistance in nanoscale electrical contacts.First, we study the current density-voltage (J-V) characteristics of dissimilar metal-insulator-metal (MIM) nanoscale tunneling junctions using a self-consistent quantum model. Tunneling type contacts are ubiquitous as they can be formed when a thin insulator layer or gap exists between two contacting members. Our model includes electron emissions from both the cathode and anode, and the effects of image charge potential, space charge and exchange correlation potential. The J-V curves span three regimes: direct tunneling, field emission, and space-charge-limited regime. Unlike similar MIM junctions, the J-V curves are polarity dependent. The forward and reverse bias J-V curves and their crossover behaviors are examined in detail for various regimes, over a wide range of material properties. It is found that the asymmetry between the current density profiles increases with the work function difference between the electrodes, insulator layer thickness, and relative permittivity of the insulator. This asymmetry is profound in the field emission regime and is insignificant in the direct tunneling, and space charge limited regimes. Next, we study the current distribution and contact resistance in ohmic, tunneling and two-dimensional (2D) material-based Schottky contacts. We modify the standard transmission line model (TLM) to include the effects of spatially varying specific contact resistivity ρ_c along the contact length. Both Cartesian and circular (or annular) contacts are analyzed. The local voltage-dependent ρ_c along the contact length is calculated self-consistently by solving the lumped circuit TLM equations coupled with the quantum tunneling model for MIM junctions, or the thermionic emission current injection model for 2D materials. We find that current distribution and contact resistance depend strongly on input voltage, contact dimension and geometry, and material properties. We also propose to reduce contact resistance in 2D-material-based electrical contacts by roughness engineering of the contact interfaces. The results for ohmic contact are verified with finite element method (FEM) based simulations, and the 2D-material based calculations are validated with existing theory and experiments. We further extend this work and demonstrate a method to mitigate current crowding, by engineering the interface layer properties and geometry. We find that current steering and redistribution can be realized by strategically designing the specific contact resistivity ρ_c along the contact length. We also find that introducing a nanometer scale thin insulating tunneling gap between highly conductive contact members can greatly reduce current crowding while maintaining similar total contact resistance.
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Title: MULTIPACTOR DISCHARGE WITH TWO-FREQUENCY RF FIELDS
Creator: Iqbal, Asif
Date: 2021
Collection: Electronic Theses & Dissertations
Description: Multipactor is a nonlinear ac discharge in which a high frequency rf field creates an electron avalanche sustained through secondary electron emission from metallic or dielectric surfaces. Multipactor discharge can adversely affect various rf systems, such as telecommunications systems, high power electromagnetic sources, and accelerator structures. The restricted frequency spectrum and the cluttered satellite orbits require a single spacecraft to perform the same or enhanced functions which...
Show moreMultipactor is a nonlinear ac discharge in which a high frequency rf field creates an electron avalanche sustained through secondary electron emission from metallic or dielectric surfaces. Multipactor discharge can adversely affect various rf systems, such as telecommunications systems, high power electromagnetic sources, and accelerator structures. The restricted frequency spectrum and the cluttered satellite orbits require a single spacecraft to perform the same or enhanced functions which previously required several satellites. This necessitates complex multi-frequency operation for a much-enlarged orbital capacity and mission, where the requirement of high power rf payload significantly increases the threat of multipactor. This work provides a comprehensive understanding of multipactor discharge driven by two-frequency rf fields. The study provides important results on single and two-surface multipactor, including multipactor mitigation, migration of electron trajectory, and frequency domain analysis.We use Monte Carlo simulations and analytical calculations to obtain single surface multipactor susceptibility diagrams with two-frequency rf fields. We present a novel multiparticle Monte Carlo simulation model with adaptive time steps to investigate the time dependent physics of the single surface multipactor. The effects of the relative strength and phase of the second carrier mode as well as the frequency separation between the two carrier modes are studied. It is found that two-frequency operation can reduce the multipactor strength compared to single-frequency operation with the same total rf power. Migration of the multipactor trajectory is demonstrated for different configurations of the two-frequency rf fields. Formation of beat waves is observed in the temporal profiles of the surface charging electric field with small frequency separation between the two carrier modes. We study the amplitude spectrum of the surface charging field due to multipactor in the frequency domain. It is found that for the single-frequency rf operation, the normal electric field consists of pronounced even harmonics of the driving rf frequency. For two-frequency rf operation, spectral peaks are observed at various frequencies of intermodulation product of the rf carrier frequencies. Pronounced peaks are observed at the sum and difference frequencies of the carrier frequencies, at multiples of those frequencies, and at multiples of the carrier frequencies. We also study two surface multipactor with single- and two-frequency rf fields using Monte Carlo simulations and CST. The effects of the relative strength and phase of the second carrier mode, and the frequency separation between the two carrier modes on multipactor susceptibility are studied. Regions of single and mixed multipactor modes are observed in the susceptibility chart. The effect of space charge on multipactor susceptibility and the time dependent physics is also studied.
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Title: Metamodeling in Evolutionary Multi-Objective Optimization for constrained and unconstrained Problems
Creator: Hussein, Rayan
Date: 2022
Collection: Electronic Theses & Dissertations
Description: One of the main difficulties in applying an optimization algorithm to a practical problem is that the evaluation of objectives and constraints often involve computationally expensive procedures. To handle such problems, a metamodel (or surrogate model, or response surface approximations) is first formed from a few exact (high-fidelity) solution evaluations, and then optimized by an algorithm in a progressive manner. However, there has been lukewarm interest in finding multiple trade-off...
Show moreOne of the main difficulties in applying an optimization algorithm to a practical problem is that the evaluation of objectives and constraints often involve computationally expensive procedures. To handle such problems, a metamodel (or surrogate model, or response surface approximations) is first formed from a few exact (high-fidelity) solution evaluations, and then optimized by an algorithm in a progressive manner. However, there has been lukewarm interest in finding multiple trade-off solutions for multi-objective optimization problems using surrogate models. The literature on surrogate modeling for constrained optimization problems is also rare. The difficulty lies in the requirement ofbuilding and solving multiple surrogate models, one for each Pareto-optimal solution. In this study, we propose a taxonomy of different possible metamodeling frameworks for multi-objective optimization and provide a comparative study by discussing advantages and disadvantages of each framework. Also, we argue that it is more efficient to use different metamodeling frameworks at different stages of the optimization process. Thereafter, we propose a novel adaptive method for switching among different metamodeling frameworks. Moreover, we observe the convergence behavior of the proposed approaches is better with a trust regions method applied within the metamodeling frameworks. The results presented in this study are obtained using the well-known Kriging metamodeling approach. Based on our extensive simulation studies on proposed frameworks, we report new and interesting observations about the behavior of each metamodeling framework, which may provide salient guidelines for further studies in this emerging area within evolutionary multi-objective optimization. Results of this study clearly show the efficacy and efficiency of the proposed adaptive switching approach compared to three recently-proposed other metamodeling algorithms on challenging multi-objective optimization problems using a limited budget of high-fidelity evaluations.
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Title: Microwave Imaging Using a Tunable Reflectarray Antenna and Superradiance in Open Quantum Systems
Creator: Tayebi, Amin
Date: 2017
Collection: Electronic Theses & Dissertations
Description: Theory, experiment, and computation are the three paradigms for scientific discoveries. This dissertation includes work in all three areas. The first part is dedicated to the practical design and development of a microwave imaging system, a problem mostly experimental and computational in nature. The second part discusses theoretical foundations of possible future advances in quantum signal transmission. In part one, a new active microwave imaging system is proposed. At the heart of this...
Show moreTheory, experiment, and computation are the three paradigms for scientific discoveries. This dissertation includes work in all three areas. The first part is dedicated to the practical design and development of a microwave imaging system, a problem mostly experimental and computational in nature. The second part discusses theoretical foundations of possible future advances in quantum signal transmission. In part one, a new active microwave imaging system is proposed. At the heart of this novel system lies an electronically reconfigurable beam-scanning reflectarray antenna. The high tuning capability of the reflectarray provides a broad steering range of +\- 60 degrees in two distinct frequency bands: S and F bands. The array, combined with an external source, dynamically steers the incoming beam across this range in order to generate multi-angle projection data for target detection. The collected data is then used for image reconstruction by means of time reversal signal processing technique. Our design significantly reduces cost and operational complexities compared to traditional imaging systems. In conventional systems, the region of interest is enclosed by a costly array of transceiver antennas which additionally requires a complicated switching circuitry. The inclusion of the beam scanning array and the utilization of a single source, eliminates the need for multiple antennas and the involved circuitry. In addition, unlike conventional setups, this system is not constrained by the dimensions of the object under test. Therefore the inspection of large objects, such as extended laminate structures, composite airplane wings and wind turbine blades becomes possible. Experimental results of detection of various dielectric targets as well as detecting anomalies within them, such as defects and metallic impurities, using the imaging prototype are presented.The second part includes the theoretical consideration of three different problems: quantum transport through two different nanostructures, a solid state device suitable for quantum computing and spherical plasmonic nanoantennas and waveguides. These three physically different systems are all investigated within a single quantum theory; the effective non-Hermitian Hamiltonian framework. The non-Hermitian Hamiltonian approach is a convenient mathematical formalism for the description of open quantum systems. This method based on the Feshbach projection formalism provides an alternative to popular methodssuch as the Feynman diagrammatic techniques and the master equation approach that are commonly used for studying open quantum systems. It is formally exact but very flexible and can be adjusted to many specific situations. One bright phenomenon emerging in the situation with a sufficiently strong continuum coupling in the case when the number of open channels is relatively small compared to the number of involved intrinsic states is the so-called superradiance. Being an analog of superradiance in quantum optics, this term stands for the formation in the system of a collective superposition of the intrinsic states coherently coupled to the same decay channel. The footprint of superradiance in each system is investigated in detail. In the quantum transport problem, signal transmission is greatly enhanced at the transition to superradiance. In the proposed solid state based charge qubit, the superradiant states effectively protect the remaining internal states from decaying into the continuum and hence increase the lifetime of the device. Finally, the superradiance phenomenon provides us a tool to manipulate light at the nanoscale. It is responsible for the existence of modes with distinct radiation properties in a system of coupled plasmonic nanoantennas: superradiant states with enhanced and dark modes with extremely damped radiation. Furthermore, similar to the quantum case, energy transport through a plasmonic waveguide is greatly enhanced.
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Title: Microwave and millimeter wave system integration with additive manufacturing
Creator: Craton, Michael Thomas
Date: 2020
Collection: Electronic Theses & Dissertations
Description: This dissertation demonstrates a collection of strategies to package and heterogeneously integrate microwave and millimeter wave (mm-wave) electronics using additive manufacturing (AM). These strategies not only facilitate heterogeneous integration and higher functional density of a system-in-package (SiP)/system-on-package (SoP), but furthermore allow for structures and performance that is difficult or impossible to match with conventional manufacturing strategies. These strategies are...
Show moreThis dissertation demonstrates a collection of strategies to package and heterogeneously integrate microwave and millimeter wave (mm-wave) electronics using additive manufacturing (AM). These strategies not only facilitate heterogeneous integration and higher functional density of a system-in-package (SiP)/system-on-package (SoP), but furthermore allow for structures and performance that is difficult or impossible to match with conventional manufacturing strategies. These strategies are implemented using aerosol jet printing, but may be applicable to other sorts of additive manufacturing technologies such as ink-jet printing. The processes developed in order to facilitate these procedures are described, including the use of multi-material aerosol jet printing (MMAJP) for the manufacture of composites and functionally graded materials for use in mm-wave circuits, and a chip-first approach to microwave and mm-wave circuit packaging. These processes enable the production of application specific SiP/SoP electronics for use in radar, communications, imaging, sensing, as well as the supporting circuitry such as filters and antennas which may be difficult or expensive to implement with semiconductor processes. Included are demonstrations of the integration of some of these strategies in complete packages. Characterization of materials used including conductors and dielectrics are presented, as well as simulations and measurements of package sub-components, and complete packages. Finally, the future of this research is discussed.
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Title: Millimeter-wave microsystems using additive manufacturing process
Creator: Qayyum, Jubaid Abdul
Date: 2020
Collection: Electronic Theses & Dissertations
Description: In recent years, researchers have been working to explore the millimeter-wave frequency domain for wireless technology to cope with the immense demand for high bandwidth for faster wireless applications such as communication and remote sensing in general. In wireless communication technology, high frequency of the mm-wave systems offers high bandwidth transmission for faster data transmission. The mm-wave frequency has also been approved by FCC for commercial applications like 5G...
Show moreIn recent years, researchers have been working to explore the millimeter-wave frequency domain for wireless technology to cope with the immense demand for high bandwidth for faster wireless applications such as communication and remote sensing in general. In wireless communication technology, high frequency of the mm-wave systems offers high bandwidth transmission for faster data transmission. The mm-wave frequency has also been approved by FCC for commercial applications like 5G communications that will deliver a more reliable, dependable and scalable cellular technology with high rate and low latency for the network users. It also promises to facilitate high data communication among devices and humans as well as other devices, the phenomena that gave rise to an emerging field known as the "Internet-of-Things". For remote sensing, higher frequencies of the mm-wave offer higher spatial and range resolution that can enable more intelligent sensor technologies.The fabrication and manufacturing process of mm-wave systems become increasingly difficult and expensive due to size reduction at smaller wavelengths. To overcome these problems, system on package (SoP) technology has gained a lot of attention. The SoP approach combines multiple integrated circuits and passive components using different packaging and interconnect approaches into a miniaturized micro-system module. Additive manufacturing (AM), also colloquially known as 3-D printing, is considered as a promising method for packaging in SoP solutions because it enables rapid prototyping and large-scale production at an affordable cost and minimal environmental impact.This work primarily focuses on the development of mm-wave microsystems by integrating chips with AM process using aerosol jet printing (AJP). Several mm-wave transceiver components that ranges from Ka-band to W-band are designed and realized in a state-of-the-art silicon-germanium IC foundry process, and are characterized to be used in complete transceiver system using 3-D printing packaging. These include a 28-60 GHz Single-Pole Double-Throw (SPDT) switch, 28-60 GHz Low-noise amplifier (LNA), 15-100 GHz downconverting mixer, K-Band upconverting mixer, V-band upconverting mixer, and a 90 GHz MMIC frequency tripler.The feasibility of using AJP in mm-wave regime and the ink characteristics were also studied. For any AM process to be an all-in-one packaging solution, it should have the capability of realizing conducting as well as dielectric materials. Silver and polyimide inks were used in this work to demonstrate a chip-to-chip interconnection and a comparison with the traditional packaging technique is also discussed. An ultra-wideband interconnect from 0.1-110 GHz was implemented using AJP. The conductivity of the silver ink and its viability to be used in flexible electronics was also considered.
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Title: Models for Evaluation and Optimization of Grid-Scale Energy Storage in Presence of Renewable Energy
Creator: Bera, Atri
Date: 2021
Collection: Electronic Theses & Dissertations
Description: Power grids across the world are undergoing remarkable changes in recent times fueled by the extensive integration of renewable energy resources (RERs). While it has been well established that RERs help to alleviate environmental concerns, the high penetration of these resources poses some serious challenges to the reliability and stability of the power grid due to their intermittent nature and low-inertia characteristics. Energy storage systems (ESSs) can provide effective solutions to the...
Show morePower grids across the world are undergoing remarkable changes in recent times fueled by the extensive integration of renewable energy resources (RERs). While it has been well established that RERs help to alleviate environmental concerns, the high penetration of these resources poses some serious challenges to the reliability and stability of the power grid due to their intermittent nature and low-inertia characteristics. Energy storage systems (ESSs) can provide effective solutions to the aforementioned problems. These devices are well suited for providing multiple services to the power grid due to their flexibility in operation, high ramp rates, and decreasing costs. This work investigates the role of ESSs in alleviating the critical issues concerning the power grid in recent times and the economic viability of such solutions. First, a novel analytical approach is developed for sizing ESSs to maintain grid frequency stability by providing inertial support. This approach provides a solution to the problem of reduced inertia in a system with high penetration of RERs, which may lead to frequency stability issues or blackouts in more severe cases. A comprehensive investment planning framework for ESS projects is also developed, which can estimate the lifetime revenue of ESSs participating in market services while considering battery degradation. A new planning strategy is then presented, which brings together the technical and economic aspects of deploying ESSs for providing inertial support to the grid. This techno-economic framework is capable of optimally sizing ESSs for providing inertial support to the grid while minimizing the operational costs of the system by participating in electricity markets. Besides considering the stability issues of the modern power grid, the depleting reliability of the system due to high RER penetration is also considered in this work. A transmission planning approach is developed for this purpose, which can reduce the variability of wind power and enhance the reliability of wind-integrated systems by jointly utilizing ESSs and wind power aggregation.
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Title: Multi-Modality Nondestructive Evaluation Techniques for Inspection of Plastic and Composite Pipeline Networks
Creator: Alzuhiri, Mohand
Date: 2022
Collection: Electronic Theses & Dissertations
Description: The extensive adoption of plastic pipelines is a growing phenomenon in different fields of the industry, with applications that extend from municipal water and sewer systems to the water lines in nuclear reactors. The large-scale adoption is motivated by the unique features of plastics like corrosion and chemical resistance, low cost, and design flexibility. While the dielectric nature of plastic pipelines provides unique design capabilities, it also introduces new challenges for the...
Show moreThe extensive adoption of plastic pipelines is a growing phenomenon in different fields of the industry, with applications that extend from municipal water and sewer systems to the water lines in nuclear reactors. The large-scale adoption is motivated by the unique features of plastics like corrosion and chemical resistance, low cost, and design flexibility. While the dielectric nature of plastic pipelines provides unique design capabilities, it also introduces new challenges for the operators when it comes to inspecting and ensuring the integrity of these pipelines’ networks. In this study, a multi-modal approach is adopted to address the threats affecting the safety of small diameter plastic pipelines and explore possible inspection solutions for emerging materials like composites. Structured light endoscopes with RGB-D inspection capability were developed for the inspection of surface defects in small diameter pipelines with novelties a) Design and miniaturization of RGB-D structured light sensor with electronic stabilization, b) Development of an algorithm to automatically calibrate the sensor when placed in a cylindrical environment, c) Design of a single shot phase measurement SL sensor that employs the sensor movement to improve the 3D reconstruction, and d) Design a stereoscopic SL sensor for 360-degree inspection. EM-based inspection was adopted to inspect subsurface defects and classify materials around the inspected pipelines. An investigative study was performed to test the probability of detecting cold fusion in butt fusion joints by using emerging NDE techniques, and a coplanar capacitive sensor was designed for the detection of legacy crossbores in gas pipelines. Finally, a thermoacoustic imaging system was developed in this study with potential applications for the inspection of composites and medical imaging. The novelties of this work can be summarized as follows: a) Development of a simulation model to study the thermoacoustic waves generation and the effect of multiple experimental parameters on the performance of thermoacoustic imaging systems, b) Improving the signal to noise ratio of pulsed TAI imaging systems by adoption non-coherent pulse compression. In summary, this study presents a multi-modal approach for the inspection of pipeline networks by adopting optical RGB-D imaging sensors for surface inspection, EM-based sensors for subsurface inspection and classification of objects outside the pipe, and finally, a hybrid imaging method with potential applications in medical imaging and inspection of composites.
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Title: NETWORK OF UNMANNED SURFACE VEHICLES : DESIGN AND APPLICATION TO TARGET TRACKING
Creator: Panetta, Chandler J.
Date: 2021
Collection: Electronic Theses & Dissertations
Description: Unmanned surface vehicles (USVs) have gained increased attention in environmental monitoring, navigation assistance, search-and-rescue, and other fields over the past three decades. USVs provide an effective platform for mobile sensing applications and offer flexibility in specific capabilities. This work presents a network of compact USVs that are capable of deploying underwater sensors using an automated winch. The small, maneuverable nature of each USV is ideal for inland bodies of water,...
Show moreUnmanned surface vehicles (USVs) have gained increased attention in environmental monitoring, navigation assistance, search-and-rescue, and other fields over the past three decades. USVs provide an effective platform for mobile sensing applications and offer flexibility in specific capabilities. This work presents a network of compact USVs that are capable of deploying underwater sensors using an automated winch. The small, maneuverable nature of each USV is ideal for inland bodies of water, and the relatively large payload capacity allows for surveys that last multiple hours. Motivated by the application of acoustic telemetry-based fish movement tracking, this work focuses on using a network of USVs to localize an underwater acoustic tag by exploiting the time-difference-of-arrival (TDOA) of the emitted signal. A distributed TDOA-based particle filter (PF) algorithm is proposed for localizing a moving target modeled by a discrete-time correlated random walk (DCRW). Furthermore, an online model learning method is explored, where target position estimates are used to update the unknown probability distributions of the target’s movement model. Through numerical simulations, the distributed PF is shown to result in effective estimation of the target position when a node is connected to a network that collectively has an adequate number of TDOA measurements. Additionally, the efficacy of online model learning in handling model uncertainties is demonstrated in simulation studies.TDOA-based localization algorithms are further validated in field experiments using a network of four USVs carrying acoustic telemetry equipment. In particular, TDOA and GPS data are collected and used to assess the target estimation performance for the distributed TDOA-based PF and a distributed TDOA-based extended Kalman filter (EKF) under different settings for the network topology.
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Title: Nanoengineered tissue scaffolds for regenerative medicine in neural cell systems
Creator: Tiryaki, Volkan Mujdat
Date: 2013
Collection: Electronic Theses & Dissertations
Description: Central nervous system (CNS) injuries present one of the most challenging problems. Regeneration in the mammal CNS is often limited because the injured axons cannot regenerate beyond the lesion. Implantation of a scaffolding material is one of the possible approaches to this problem. Recent implantations by our collaborative research group using electrospun polyamide nanofibrillar scaffolds have shown promising results in vitro and in vivo. The physical properties of the tissue scaffolds have...
Show moreCentral nervous system (CNS) injuries present one of the most challenging problems. Regeneration in the mammal CNS is often limited because the injured axons cannot regenerate beyond the lesion. Implantation of a scaffolding material is one of the possible approaches to this problem. Recent implantations by our collaborative research group using electrospun polyamide nanofibrillar scaffolds have shown promising results in vitro and in vivo. The physical properties of the tissue scaffolds have been neglected for many years, and it has only recently been recognized that significant aspects include nanophysical properties such as nanopatterning, surface roughness, local elasticity, surface polarity, surface charge, and growth factor presentation as well as the better-known biochemical cues.The properties of: surface polarity, surface roughness, local elasticity and local work of adhesion were investigated in this thesis. The physical and nanophysical properties of the cell culture environments were evaluated using contact angle and atomic force microscopy (AFM) measurements. A new capability, scanning probe recognition microscopy (SPRM), was also used to characterize the surface roughness of nanofibrillar scaffolds. The corresponding morphological and protein expression responses of rat model cerebral cortical astrocytes to the polyamide nanofibrillar scaffolds versus comparative culture surfaces were investigated by AFM and immunocytochemistry. Astrocyte morphological responses were imaged using AFM and phalloidin staining for F-actin. Activation of the corresponding Rho GTPase regulators was investigated using immunolabeling with Cdc42, Rac1, and RhoA. The results supported the hypothesis that the extracellular environment can trigger preferential activation of members of the Rho GTPase family, with demonstrable morphological consequences for cerebral cortical astrocytes. Astrocytes have a special role in the formation of the glial scar in response to traumatic injury. The glial scar biomechanically and biochemically blocks axon regeneration, resulting in paralysis. Astrocytes involved in glial scar formation become reactive, with development of specific morphologies and inhibitory protein expressions. Dibutyryl cyclic adenosine monophosphate (dBcAMP) was used to induce astrocyte reactivity. The directive importance of nanophysical properties for the morphological and protein expression responses of dBcAMP-stimulated cerebral cortical astrocytes was investigated by immunocytochemistry, Western blotting, and AFM. Nanofibrillar scaffold properties were shown to reduce immunoreactivity responses, while PLL Aclar properties were shown to induce responses reminiscent of glial scar formation. Comparison of the responses for dBcAMP-treated reactive-like and untreated astrocytes indicated that the most influential directive nanophysical cues may differ in wound-healing versus untreated situations.Finally, a new cell shape index (CSI) analysis system was developed using volumetric AFM height images of cells cultured on different substrates. The new CSI revealed quantitative cell spreading information not included in the conventional CSI. The system includes a floating feature selection algorithm for cell segmentation that uses a total of 28 different textural features derived from two models: the gray level co-occurance matrix and local statistics texture features. The quantitative morphometry of untreated and dBcAMP-treated cerebral cortical astrocytes was investigated using the new and conventional CSI, and the results showed that quantitative astrocyte spreading and stellation behavior was induced by variations in nanophysical properties.
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Title: Neural mechanisms of goal-directed action selection by prefrontal cortex : implications for brain-machine interfaces
Creator: Mohebi, Ali
Date: 2014
Collection: Electronic Theses & Dissertations
Description: Initiating a movement goal and maintaining that goal throughout the planning and execution of a goal-directed action is an essential element of all goal-directed behavior. In thecontext of Brain Machine Interfaces (BMIs), a direct communication pathway between thebrain and a man-made computing device, continuous access to movement goals is essential,so as to guide the control of neuroprosthetic limbs that provide neurologically impaired subjects with an alternative to their lost motor...
Show moreInitiating a movement goal and maintaining that goal throughout the planning and execution of a goal-directed action is an essential element of all goal-directed behavior. In thecontext of Brain Machine Interfaces (BMIs), a direct communication pathway between thebrain and a man-made computing device, continuous access to movement goals is essential,so as to guide the control of neuroprosthetic limbs that provide neurologically impaired subjects with an alternative to their lost motor function. The Prefrontal cortex (PFC) has beensuggested as an executive control area of the brain that bridges the temporal gap betweenincoming sensory information and ensuing motor actions. The mechanisms underlying thedynamics of PFC neural activity, however, remain poorly understood. The main objectiveof this dissertation is to elucidate the role of PFC neurons in mediating goal initiation andmaintenance during goal-directed behavior.Using a combination of electrophysiological recordings, optogenetic and pharmacological manipulation of population activity and behavioral assays in awake behaving subjects,we demonstrate that the PFC plays a critical role in the planning and execution of a twoalternative forced choice task. In particular, PFC neurons were mostly goal selective duringthe choice epoch of the task when subjects had to select the action with the highest utility while suppressing all other unrewarded actions. Decoding PFC neural activity usingadvanced machine learning algorithms showed robust single trial prediction of motor goals,suggesting that PFC may be a candidate site for inferring volitional motor intent. In addition, results from inactivation experiments demonstrate a lateralized performance declinewith respect to the inactivation site, further confirming the critical role of the PFC in mediating the motor- but not the sensory- information during the execution of goal-directedbehavior. Taken together, our results suggest that the design of next generation BMIs couldbe further improved by incorporating goal information from cognitive control areas of thebrain, thereby augmenting the capability of current designs that only rely on decoding themoment-by-moment kinematics of intended limb movements from motor areas of the brain.
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