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Title: Three agendas for changing the public stigma of mental illness.
Creator: Corrigan, Patrick
Date: 2018, 2017
Publisher: American Psychological Association
Description: OBJECTIVE:...
Show moreOBJECTIVE: Antistigma programs may be guided by 3 differing agendas: services (promote treatment engagement), rights (help people achieve rightful goals), and self-worth (facilitate self-worth and efficacy). This study examined the construct validity of this perspective by examining the factor structure of importance ratings of the 3 agendas. The study examined how importance might be viewed differently by the population as a whole versus a subsample of people who reported previous experience with mental health services and hence could be directly harmed by stigma. METHODS: 373 individuals recruited using Mechanical Turk completed importance ratings for each of the 3 agendas. Measures of public stigma were completed to examine concurrent validity of importance ratings. Those who reported taking medications for a psychiatric disorder were divided into a separate group and completed a measure of self-stigma. RESULTS: Outcomes seemed to confirm the factor structure of the 3 agendas model thereby offering partial support for the framework. Group analyses showed the services agenda was viewed as more important than rights or self-worth. People with mental health experience viewed the services agenda as more important than the other 2. However, dividing the mental health group into low and high self-stigma revealed that those with low self-stigma rated the rights agenda as more important. Conclusions and Implication for Practice: Participants with lower self-stigma identify the harm brought by stigma and thus endorse rights and self-worth more than those with higher self-stigma. Implications of these findings are discussed to assist to prioritize agendas for public health campaigns.
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Title: SYSTEMWIDE INTERSECTION SIGNAL TIMING OPTIMIZATION SIMULTANEOUSLY MINIMIZING VEHICLE AND PEDESTRIAN DELAYS
Creator: Roshandeh, Arash Moradkhani
Date: 2013, 2013-07
Description: The ever-growing traffic volume especially in urban areas stretches the transportation system to be operated at near or exceeding capacity and...
Show moreThe ever-growing traffic volume especially in urban areas stretches the transportation system to be operated at near or exceeding capacity and causes congestion. Expanding system capacity and effectively utilizing available capacity could help reduce traffic congestion. In most of cases, adding extra travel lanes in dense urban street networks is not feasible any more due to land scarcity. This study introduces a new method for signal timing optimization that is carried out by adjusting green splits of AM peak, PM peak, and rest of the day timing plans for each signalized intersection in the network without changing the existing cycle lengths and signal coordination to minimize total vehicle and pedestrian delays per cycle. The proposed method contains a basic model that handles vehicle delays only and an enhanced model that simultaneously addresses vehicle and pedestrian delays using two different pedestrian delay estimation methods. Both models are incorporated into an agent-based regional travel demand forecasting tool for detailed traffic assignments using data on Chicago regional travel demand, traffic counts, geometric designs, and signal timing plans for major intersections in the Chicago Central Business District (CBD) street network. The computational experiment reveals that vehicle delays in the CBD area could reduce by 10 percent when only considering vehicle delays and 5 percent when simultaneously considering vehicle and pedestrian delays for signal timing optimization. Considering the intersections safety analysis, it has been found that signals timing optimization in all four areas combined without considering pedestrian delays decreased different crash types under various severities for multiple vehicle collisions as well as vehicle-pedestrian ones. Taking care of both vehicles and pedestrians delay xvi vii simultaneously, using HCM method, just a very few situations represent slight increases in crash frequencies and all other cases indicate crash reductions. Compared with the sensitivity analysis results using the HCM method for calculating pedestrian delays in the enhanced model applications, the Levinson method produces different results even though crash frequency reduction trends are almost the same as HCM method results.
PH.D in Civil Engineering, July 2013
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Title: THE ASSOCIATION BETWEEN PSYCHOLOGICAL FACTORS AND GLYCEMIC CONTROL IN TYPE 2 DIABETIC PATIENTS ON INSULIN
Creator: AraÚjo, Fabiana Souza
Date: 2016, 2016-12
Description: This study investigated the relationship among several psychological constructs and glycemic control in Type 2 diabetes patients on multiple...
Show moreThis study investigated the relationship among several psychological constructs and glycemic control in Type 2 diabetes patients on multiple daily doses of insulin. Participants were mostly impoverished and underserved minorities and were all patients of a diabetes specialty clinic in a county hospital of a metropolitan area in the Midwest of the U.S. Eighty-two participants completed self-reported questionnaires on diabetes, self-efficacy, psychological distress, diabetes-related distress, adherence to medication, diabetes knowledge, literacy, numeracy, health locus of control and had their HbA1c tested. Results of multiple regression analyses controlling for age, gender, and duration of diabetes indicted that higher self-efficacy (p = .005) was associated with better glycemic control. Mediation analyses did not yield significant results when testing whether self-efficacy mediated the relationship between some psychological constructs (i.e., diabetes knowledge, literacy, or numeracy) and glycemic control. Similarly, no significant results were found in mediation analyses neither when adherence to medication was tested as a mediator between diabetes knowledge and glycemic control nor when diabetes-related distress was tested as a mediator between psychological distress and glycemic control. These results emphasize the importance of self-efficacy among underserved minority patient in their abilities to perform all complex behaviors required to properly manage diabetes. Future studies with larger sample sizes should expand our findings and provide more information on some of our non-significant findings.
Ph.D. in Psychology, December 2016
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Title: DESIGN AND PERFORMANCE ASSESSMENT OF MULTI-MODAL MOBILE ROBOTS
Creator: Kalantari, Arash
Date: 2015, 2015-05
Description: This thesis is focused on developing multi-modal mobile robots, i.e. robots that can operate in more than one domain. For decades, researchers...
Show moreThis thesis is focused on developing multi-modal mobile robots, i.e. robots that can operate in more than one domain. For decades, researchers have been trying to improve locomotion capabilities of robots that operate in a single domain: on the ground, on inclined surfaces, in the air, or in water. A prevailing approach in design of hybrid robots is to simply attach systems designed for a single domain together. In order to reduce the complexity of the hybrid robot, a different design approach is taken in this thesis by attempting to keep the hardware resources on the system as low as possible. To this end, two hybrid aerial and terrestrial platforms have been developed: the walking quadrotor and the HyTAQ, the Hybrid Terrestrial and Aerial Quadrotor. In both platforms, ight is achieved through a quadrotor configuration; four actuators provide the required thrust. The walking quadrotor uses a single actuator set for both walking and ying by means of a unique compliant mechanism. This mechanism uses two separate linear movements to make walking possible. The horizontal movement of the leg is driven by running the propellers in reverse and the vertical movement is actuated by shape memory alloy (SMA) wires. An experimental prototype of this robot proves the functionality of the design. However, the experiments suggest that the application of the robot is efficient only where ground movement is a small portion of the whole mission. This is mainly due to the low efficiency of the propellers rotating in reverse and large time constant of the SMA wires, which makes walking slow. The terrestrial locomotion of HyTAQ has been made possible by adding a cylindrical cage, connected to the quadrotor through a revolute joint. This allows the cage to roll freely with respect to the body of the quadrotor, making the terrestrial locomotion possible. Moreover, the same ight actuators and control commands can be used to control terrestrial mode. An analysis of the system's energy consumption shows that the addition of the terrestrial locomotion improves the efficiency of the aerial-only quadrotor by increasing the overall operation range and time. This has been experimentally verified by showing that the HyTAQ's terrestrial range is 11 times greater compared to ight range of the quadrotor at the same speeds. Developing a hybrid aerial and scansorial robot is the next goal of this research. The first step toward this goal has been taken as part of this thesis by developing a method that enables a quadrotor to land and take-off from smooth vertical surfaces autonomously. A Microsoft Kinect sensor is used to localize the MAV and a PID controller is used to control the perching maneuver. A servo actuated gripper, mounted in front of the robot, makes attachment and detachment possible. The experimental results show that the robot can perch successfully in more than 90% of the experiments, which indicates the robustness of the proposed method.
Ph.D. in Mechanical and Aerospace Engineering, May 2015
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Title: ADVANCED MATERIALS ENABLED BY ATOMIC LAYER DEPOSITION FOR HIGH ENERGY DENSITY RECHARGEABLE BATTERIES
Creator: Chen, Lin
Date: 2017, 2017-05
Description: In order to meet the ever increasing energy needs of society and realize the US Department of Energy (DOE)’s target for energy storage,...
Show moreIn order to meet the ever increasing energy needs of society and realize the US Department of Energy (DOE)’s target for energy storage, acquiring a fundamental understanding of the chemical mechanisms in batteries for direct guidance and searching novel advanced materials with high energy density are critical. To realize rechargeable batteries with superior energy density, great cathodes and excellent anodes are required. LiMn2O4 (LMO) has been considered as a simpler surrogate for high energy cathode materials like NMC. Previous studies demonstrated that Al2O3 coatings prepared by atomic layer deposition (ALD) improved the capacity of LMO cathodes. This improvement was attributed to a reduction in surface area and diminished Mn dissolution. However, here we propose a different mechanism for ALD Al2O3 on LMO based on in-situ and ex-situ investigations coupled with density functional theory calculations. We discovered that Al2O3 not only coats the LMO, but also dopes the LMO surface with Al leading to changes in the Mn oxidation state. Different thicknesses of Al2O3 were deposited on nonstoichiometric LiMn2O4 for electrochemical measurements. The LMO treated with one cycle of ALD Al2O3 (1×Al2O3 LMO) to produce a sub-monolayer coating yielded a remarkable initial capacity, 16.4%higher than its uncoated LMO counterpart in full cells. The stability of 1×Al2O3 LMO is also much better as a result of stabilized defects with Al species. Furthermore, 4×Al2O3 LMO demonstrates remarkable capacity retention. Stoichiometric LiMn2O4 was also evaluated with similar improved performance achieved. All superior results, accomplished by great stability and reduced Mn dissolution, is thanks to the synergetic effects of Al-doping and ALD Al2O3 coating.Turning our attention to the anode, we again utilized aluminum oxide ALD to form conformal films on lithium. We elaborately designed and studied, for the first time, the growth mechanism during Al2O3 ALD on lithium metal in-situ quart crystal microbalance (QCM) measurements and found larger growth than expected during the initial cycles. Besides, we discovered that electrolytes show much enhanced wettability on Li with Al2O3 coating, leading to uniform and dense solid electrolyte interphase formation as well as less electrolyte required for battery operations. Also, we achieved more than 2 times longer cycling life with protected Li and obtained Coulombic efficiencies as high as ~98% at a practical current rate of 1 mA/cm2, compared to bare Li. More significantly, when the electrolyte volume is limited (10 μL and 5 μL), the cycling life is about 4 times longer. X-ray photoelectron spectroscopy (XPS) for electrodes after cycles and in-situ transmission electron microscopy (TEM) demonstrate that most of lithium is deposited beneath the film. The more uniform Al2O3 coated lithium after cycling observed by scanning electron microscopy (SEM) verifies that ALD Al2O3 isexceptionally effective to prevent lithium dendrite formation. These results demonstrate that ALD Al2O3 coatings offer a promising route towards energy storage devices that utilize lithium metal anodes, such as Li-S batteries.
Ph.D. in Materials Science and Engineering, May 2017
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Title: DYNAMIC CONIC FINANCE VIA BACKWARD STOCHASTIC DIFFERENCE EQUATIONS AND RECURSIVE CONSTRUCTION OF CONFIDENCE REGIONS
Creator: Chen, Tao
Date: 2016, 2016-07
Description: This thesis consists of two major parts, and it contributes to the fields of mathematical finance and statistics. The contribution to...
Show moreThis thesis consists of two major parts, and it contributes to the fields of mathematical finance and statistics. The contribution to mathematical finance is made via developing new theoretical results in the area of conic finance. Specifically, we have advanced dynamic aspects of conic finance by developing an arbitrage free theoretical framework for modeling bid and ask prices of dividend paying securities using the theory of dynamic acceptability indices. This has been done within the framework of general probability spaces and discrete time. In the process, we have advanced the theory of dynamic sub-scale invariant performance measures. In particular, we proved a representation theorem of such measures in terms of a family of dynamic convex risk measures, and provided a representation of dynamic risk measures in terms of BS Es. The contribution to statistics is of fundamental importance as it initiates the theory underlying recursive computation of confidence regions for finite dimensional parameters in the context of stochastic dynamical systems. In the field of engineering, particularly in the field of control engineering, the area of recursive point estimation came to great prominence in the last forty years. However, there has been no work done with regard to recursive computation of confidence regions. To partially fill this gap, the second part of the thesis is devoted to recursive construction of confidence regions for parameters characterizing the one-step transition kernel of a time-homogeneous Markov chain.
Ph.D. In Applied Mathematics, July 2016
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Title: LEAKAGE DETECTION AND QUANTIFICATION TECHNIQUES USING VARIOUS METHODS OF NEARFIELD ACOUSTIC HOLOGRAPHY
Creator: Chelliah, Kanthasamy
Date: 2016, 2016-07
Description: This thesis proposes an acoustic technique to detect and relatively quantify leakages in buildings and enclosures using various methods of...
Show moreThis thesis proposes an acoustic technique to detect and relatively quantify leakages in buildings and enclosures using various methods of nearfield acoustic holography (NAH). This laboratory study was performed on a scaled, wooden building model. Known leakages can be created in the wooden model and the acoustic method was tested to localize and relatively quantify these known leakage areas. An acoustic source was placed inside the building model and a planar hologram measurement was performed near the surface of the building model. Various methods of NAH were applied on the hologram data to reconstruct the sound pressure field on the wall of the building model. The detection and quantification capabilities of four different NAH methods, namely, discrete Fourier transform (DFT) based NAH, equivalent source model (ESM) based NAH, boundary element method (BEM) based NAH and statistically optimized NAH (SONAH), were compared in this study. It was shown that the NAH methods were able to successfully locate and relatively quantify the area of the leakages using the reconstructions. Although all the four algorithms produced comparable results in the very nearfield, at larger hologram distances, ESM and SONAH reconstructions were more accurate than the reconstructions using the other methods. Although, ESM and SONAH produced similar results for most of the cases, ESM is more preferable due to its simplicity in implementation and less computational time requirements. Lower frequency reconstructions were found to be more accurate and advantageous in the context of leakage detection and quantification. When the hologram distance was increased more than a particular limit, all the four algorithms arrive at inaccurate reconstructions due to the very ill-conditioned propagation matrices. New filtering methods to alleviate these larger reconstruction errors were introduced and the results were demonstrated. Effects of large sensor phase mismatch were also studied. It was demonstrated that larger phase error in the measurements could result in less accurate reconstructions. Performances of various regularization parameter choice methods applied to different approaches of nearfield acoustic holography were compared at various distances of reconstructions. Generalized cross validation and Morozov methods were implemented to arrive at filtering parameters to regularize the NAH reconstructions. Morozov method did not provide any significant filtering for the geometries considered in this study. GCV method produced very accurate reconstructions when a very nearfield measurement was supplied. Four new parameter choice methods were introduced to obtain the appropriate regularization parameters for very ill-conditioned inverse problems such as NAH. These methods work very well even at larger hologram distances and when the matrix dimension is very large where other available methods fail. These new parameter choice methods are not specific for the NAH problem. They can be applied to any ill-conditioned inverse problem. The advantages of each parameter choice method were explored and discussed in detail. Effects of signal quality on the NAH reconstructions were also studied. Patch NAH was implemented successfully to extend the aperture of computational domain more than that of the measurement. Also, the challenges in obtaining a smooth solution through patch NAH were discussed. A unique, MEMS based microphone array was designed, fabricated and tested keeping the future field tests in mind. The tests show that this array produces reasonably accurate measurements that can be used for the NAH methods. GCV method was found to work well for the reconstructions from the array even at larger distances because of the smaller propagation matrix due to the less number of microphones. This portable array can be used for field tests due to its portable form factor and reasonably accurate reconstructions.
Ph.D. in Mechanical and Aerospace Engineering, July 2016
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Title: ELECTROCHEMICAL AND TERMAL MECHANISTIC STUDY OF BEYOND LITHIUM ION SYSTEMS: LITHIUM SULFUR AND LITHIUM OXYGEN CELLS
Creator: Seo, Jeongwook
Date: 2016, 2016-05
Description: Electrochemical and Thermal Mechanistic Study of Lithium Sulfur Cell. The thermal behavior of Li/S cells was studied using IMC in terms of...
Show moreElectrochemical and Thermal Mechanistic Study of Lithium Sulfur Cell. The thermal behavior of Li/S cells was studied using IMC in terms of reversible and irreversible heat generation. The heat generation profile was compared with the voltage profile during discharge of the cell and it was found that the trend of heat generation rate shows excellent correlation with the evolution of reaction voltage, which demonstrates that the IMC technique can be used as an useful tool to study the elementary reactions of the Li/S cell. A simple heat generation model provides reasonable agreement with the measured trends in the heat release. The resistive heat evolution that is calculated by over voltage has the largest portion of total cell heat generation (85%) after the IMC heat evolution model analysis. The qualitative agreement between the aforementioned experimental results and heat generation model yields a comprehensive picture of the elementary reaction steps in Li/S cell. The increase of cell conductivity can be expected to bring about low heat evolution during cell cycling by reducing resistive heat. Doped Sulfur as a conductive cathode is a good suggestion to improve cell heat behavior. Furthermore, better cell cycle capability is expected by using lithium metal oxide cathode composites. The thermal behavior of three cathode materials for lithium/sulfur (Li/S) cell, namely - sulfur, sulfur-LiFePO4 (S-LFP) composite and sulfur-LiV3O8 (S-LVO) composite were comparatively studied using Isothermal Micro-Calorimetry (IMC) at various rates of discharge current. A continuum model was used to calculate the reversible entropic heat and irreversible resistive heat generated over the discharge process and the model data was compared to the experimental data to elucidate these contributions to the overall heat generated. The S-LVO composite cathode was found to show the least heat generation during discharge. Further, Accelerating Rate Calorimetry (ARC) was used to study the thermal safety of these three cells. The cell with the S-LVO composite cathode was found to have the highest onset temperature for thermal runaway and also the lowest maximum self-heat rate. The combination of high capacity, long cycle life and thermal stability makes the S-LVO composite cathode a very promising material for Li/S cells Oxygen Reduction Reaction Studies using Rotating Ring Disk Electrode for Li-Air battery. The oxygen reduction reaction (ORR) studies in aqueous electrolytes have reported the following reaction mechanisms: (i) four electron reaction, (ii) two electron reaction and (iii) one electron chemical reaction. On the other hand, the aprotic ORR literature has no reports of four electrons and two electrons transfer reaction. The kinetics of ORR on the cathode was carried out using rotating ring disk electrode (RRDE) technique. The first step of ORR which produces the superoxide radical was investigated on glassy carbon (GC) disk in 0.1 M tetrabutylammonium bis-(trifluoromethane)imide (TBATFSI)/dimethoxyethane (DME). One-electron reduction to the superoxide radical was founded in the linear sweep voltammetry (LSV) analysis. Further, ORR to produce LiO2 and Li2O2 was carried in bis(trifluoromethane)sulfonimide-lithium(LITFSI)/DME on porous carbon coated glassy carbon electrode disk. The reaction kinetic rate on the porous carbon was calculated using the Li-O2 ORR mechanism model. The kinetic rate was compared with the kinetic rate of glassy carbon electrode. The non-aqueous system has several advantages compared to the aqueous system such as high operation voltage and non-reactive electrolyte with Li+. However this system has some critical problems such as low solubility of Li2O2 and High charge over potential. One attempted solution for these disadvantages of the non-aqueous system was to carry out water addition into the solvent which was expected to produce highly soluble LiOH with lower overpotential. Small amount of Water, 0.5 wt% added into 0.1 M LiTFSI/DME and 1 wt% added in the 0.2 M TBATFSI/DME electrolyte, showed great electrochemical performance with lower onset potential and overvoltage. The kinetics of ORR study for the non-aqueous and aqueous hybrid system was carried out using RRDE technique. Koutecky-Levich plot and Tafel slope analysis indicated two electron transfer reaction on the hydrated 0.1 M LiTFSI/DME. This hydrated system can be expected to double energy storage by two electron transfer ORR for Li-O2 Cell.
Ph.D. in Chemical Engineeering, May 2016
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Title: PROJECT SCHEDULING USING OPTIMIZED FINANCING
Creator: Alavipour, Seyyed Mohammadreza
Date: 2017, 2017-07
Description: Contractors need financing throughout a project, mainly due to retainage, which is the money that the owner withholds to make sure that the...
Show moreContractors need financing throughout a project, mainly due to retainage, which is the money that the owner withholds to make sure that the project is performed properly by the contractor. Even if an owner does not withhold retainage, financing is still necessary because the periodic payments made by the owner are usually delayed. All pertinent studies conducted so far have considered only one source of financing without any consideration of different sources and types of financing, times of cash provisions, interest rates, and repayment options. Actually, if one assumes a predetermined credit limit and one source of financing, as past researchers have done, the optimal financing cost and the schedule that satisfies all constraints may be different than when several sources of financing and undetermined credit limit are considered. The main objective of this research is to focus on the optimization of financing cost by developing a financing optimization model based on different financing alternatives. Far lower financing cost and higher profit are obtained by using the proposed model compared to all models developed in past research. The research is conducted in four stages of development. In Stage 1, a financing optimization model is developed for a schedule that uses normal (not accelerated) activities, and early activity start and finish times. This model can be used before the contract is signed to offer the lower bid or can be used after the contract is signed to obtain higher profit. In Stage 2, the time-cost tradeoff algorithm is added to the model developed in Stage 1, considering accelerated activities between the crash and normal durations. In Stage 3, the model developed in Stage 2 is augmented by considering variable activity start times. Finally, in Stage 4, the model developed in Stage 3 is further improved by expanding time-cost tradeoff to allow for time extensions beyond the contract duration. All models developed in these four stages provide not only minimum financing cost, but also the ideal work schedule that achieves minimum total cost and maximum profit. Moreover, these models provide specific timings for borrowing and repaying funds.
Ph.D. in Civil Engineering, July 2017
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Title: EFFECTS OF ARRAY SCALING ON THE ANGULAR RESOLUTION OF MICROPHONE ARRAY SYSTEMS
Creator: Aldeman, Matt
Date: 2016, 2016-12
Description: Array detection systems have been in use for nearly a century and have proven useful in a variety of applications. The most ubiquitous form of...
Show moreArray detection systems have been in use for nearly a century and have proven useful in a variety of applications. The most ubiquitous form of array is the active radar array, but in the past four decades microphone arrays have become increasingly common. Microphone arrays have traditionally been very large devices. This is because of the limited angular resolution of the traditional Delay-and-Sum (DAS) beamforming algorithm. Improved frequency-domain beamforming (FDBF) methods were developed in the 1980’s using the Fast Fourier Transform. More advanced methods have been developed in the past decade, including deconvolution methods (DAMAS, DAMAS2), methods based on the spatial coherence of point sources and sidelobes in the frequency domain (CLEAN-SC), and spatial coherence methods in the time domain (TIDY). In this investigation two sets of experiments were carried out to better understand the angular resolution characteristics of scaled microphone arrays and associated beamforming algorithms. In the first experiment five scaled microphone arrays with diameters from 0.73m to 10.98m were constructed and tested, and the data was analyzed with a variety of beamforming algorithms. In the second experiment three scaled microphone arrays and one alternative array geometry were tested with both free-field and reflective boundary conditions. The results show that the Rayleigh criterion can be exceeded under certain conditions. However, several other parameters are also important. For example, Signal-to-Noise Ratio (SNR), z-axis correction, and reflective boundaries all impact aspects of the array’s performance. In addition to increasing the array diameter and the signal frequency, results show that effective strategies to improve the angular resolution performance of an array include careful selection of beamforming algorithm, the use of appropriate beamforming integration times, and minimizing boundary reflections. The DAS algorithm is shown to offer the lowest angular resolution performance because it does not separate the acoustic source map from the point spread function of the array. The DAMAS algorithm offers the greatest angular resolution because it numerically deconvolutes the acoustic source map from the point spread function. However, deconvolution-based algorithms are the most negatively affected by the boundary reflection effects commonly seen with larger arrays. This is because the pressure field becomes contaminated with reflections and image sources, and the deconvolution approach does not make use of significant simplifying assumptions as several of the other algorithms do. The logarithmic spiral array is shown to offer versatile performance across a wide range of frequencies, while an alternative quasiperiodic array yields results that are highly frequency-dependent. It is demonstrated that this is because of gaps in the source-to-element differences coverage, and the gaps in coverage correspond to half-wavelengths of frequency bands with significantly lower angular resolution performance.
Ph.D. in Mechanical and Aerospace Engineering, December 2016
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Title: GETTING RID OF THE WIRES: A TRANSCUTANEOUS POWER AND WIDEBAND TELEMETRY SYSTEM FOR MULTI-CHANNEL NEURAL RECORDING IMPLANTS
Creator: Rush, Alexander Daniel
Date: 2012-08-08, 2012-07
Description: This dissertation focuses on development of wireless power and data transmission hardware for use in a wireless neural recording system. This...
Show moreThis dissertation focuses on development of wireless power and data transmission hardware for use in a wireless neural recording system. This involves a comprehensive review of the applications requiring or strongly benefiting from wireless power and high data rate outward telemetry, multiparametric analysis of a system for wireless power and data transmission, and a detailed description of external and implanted hardware composing such a system. In this document “implanted” or “implantable” means that the hardware referred to by these terms is designed with the intention of being fully contained within the body with no physical connections crossing the skin.
Ph.D. in Biomedical Engineering, July 2012
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Title: CHIRPLET SIGNAL DECOMPOSITION AND PARAMETER ESTIMATION ALGORITHMS FOR ULTRASONIC SIGNAL ANALYSIS
Creator: Kasaeifard, Alireza
Date: 2012-12-03, 2012-12
Description: In ultrasonic imaging systems, shape, size and orientation of the reflectors and the physical properties of the propagation path govern the...
Show moreIn ultrasonic imaging systems, shape, size and orientation of the reflectors and the physical properties of the propagation path govern the patterns of backscattered echoes. However, the backscattered echoes often interfere with each other due to closed locations, orientations and size of reflectors and may be corrupted by noise. Hence, signal modeling and parameter estimation of the ultrasonic echoes are essential for image analysis, detection, classification and diagnosis. Certain important information like position, shape and size of the reflectors can be represented by chirplet signal parameters. Similarly, in other important application area of signal modeling such as radar, sonar and speech, chirplet signal parameters are also critical. The objective of this study is to analyze the pattern of ultrasonic echoes using chirplet signal decomposition and parameter estimation techniques. Signal processing method for decomposing multiple interfering ultrasonic echoes is a major and challenging problem. The chirplet signal decomposition algorithms designed and analyzed in this investigation are based on the Fractional Fourier Transform (FrFT) and elliptic template matching applied to time-frequency distributions of ultrasonic signals. This study has a broad range of applications of importance in signal detection, estimation, and pattern recognition. Fractional Fourier Transform based Chirplet Signal Decomposition (FrFT-CSD) algorithm is proposed to analyze ultrasonic signals for NDE applications. Particularly, this method is utilized to isolate dominant chirplet echoes for successive steps in signal decomposition and parameter estimation. FrFT rotates the signal with an optimal transform order. The search of optimal transform order is conducted by determining the highest kurtosis value of the signal in the transformed domain. A simulation study reveals xi the relationship among the kurtosis, the transform order of FrFT, and the chirp rate parameter in the simulated ultrasonic echoes. Benchmark and ultrasonic experimental data are used to evaluate the FrFT-CSD algorithm. Signal processing results show that FrFT-CSD not only reconstructs signal successfully, but also characterizes echoes and estimates echo parameters accurately. To accelerate echo estimation algorithm, we present a novel method for estimating the parameters of chirp echo by means of ellipse fitting in the Time-Frequency (TF) domain. Wigner-Ville Distribution (WVD) and Short-Time Fourier Transform (STFT) of chirplets are in the form of concentric ellipses in the TF plane. The elements of ellipse such as long axis, short axis and the slope of the ellipse correspond to the chirplet parameters and this can be used for parameter estimation. To demonstrate the parameter estimation performance of ellipse fitting method, the algorithm is used to decompose an ultrasonic experimental signal consisting of many interfering echoes acquired in nondestructive testing of a steel block. The comparison between the reconstructed signal and the experimental result shows that the decomposition has been successfully performed in the presence of measurement noise and interference from microstructure scattering echoes. The Ellipse Fitting Method (EFM) employs short-time Fourier transform as the main computational load of the algorithm that makes it a good candidate for real-time applications using FFT hardware accelerators. In this study we also present a Field-Programmable Gate-Array (FPGA) implementation that is able to perform chirplet signal decomposition using EFM. The EFM algorithm has been implemented as a system-on-chip consisting hardware architecture and software code on a Xilinx Virtex-5 FPGA. The xii designed hardware architecture is a combination of an embedded Microblaze processor, IP cores, communication buses, and I/Os. The software component represents a portion of the estimation algorithm that runs on the Microblaze processor. The EFM algorithm is used to decompose an ultrasonic experimental signal consisting of many interfering echoes.. The profiling analysis shows the major portion of the execution time (i.e., 94%) is for the FFT computations. By adding and interfacing the FFT IP-core accelerator to Microblaze, the estimation time for each chirp echo is reduced by 85% (i.e. from 550 ms to 82 ms). This reduction in echo estimation is highly desirable and makes the real-time parameteric signal analysis practical.
PH.D in Electrical Engineering, December 2012
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Title: ADVANCING KNOWLEDGE OF INDOOR AEROSOL SOURCES, FATE, TRANSPORT, AND CONTROL
Creator: Azimi, Parham
Date: 2016, 2016-12
Description: Recent evidence suggests that particulate matter (of both indoor and outdoor origin) is one of the most important airborne pollutants driving...
Show moreRecent evidence suggests that particulate matter (of both indoor and outdoor origin) is one of the most important airborne pollutants driving adverse health effects worldwide. Despite our understanding of major indoor aerosol sources that contribute to adverse health effects across the population, gaps in our knowledge of some aspects of the sources, fate, transport, and control of indoor aerosols still remain. This dissertation focuses on filling three major gaps related to indoor aerosols. The first objective of this dissertation is to improve knowledge of the impacts of particle filtration in central heating, ventilation, and air-conditioning (HVAC) systems on fine particles smaller than 2.5 μm in diameter (i.e., PM2.5) and ultrafine particles smaller than 100 nm in diameter (i.e., UFPs) of outdoor origin that penetrate into the indoor environment. Results demonstrate that higher-efficiency HVAC filters can significantly reduce indoor proportions of outdoor PM2.5 and UFPs inside residences, but home vintage, climate zone, and ventilation strategy strongly influence the outcomes due to widely varying air exchange rates, HVAC system runtimes, and sources of ventilation air. The second objective of this dissertation is to improve knowledge of emissions and control of particulate matter from a recently established source of indoor pollutants: desktop three-dimensional (3D) printers. Median estimates of time-varying UFP emission rates ranged from ~108 to ~1011 #/min across all tested combinations, varying primarily by filament material and, to a lesser extent, bed temperature. It was also shown that UFP concentrations within close or moderate proximity to some desktop 3D printer and filament combinations can exceed recommended exposure levels. The most effective control strategies for reducing pollutant concentrations emitted from desktop 3D printers wereinstalling a high-flow spot ventilation system and operating the printer in a sealed enclosure with high efficiency gas and particle filtration. Finally, the third objective of this dissertation is to improve knowledge of the fate, transport, and control of infectious diseases in indoor environments through mathematical modeling of bioaerosol transmission and infection risk. Results demonstrate that Recirculating HVAC filtration can achieve risk reductions at lower costs of operation than equivalent levels of outdoor air ventilation, particularly for MERV 13-16 filters. It was also shown that in addition to the biological characteristics of respiratory pathogens, human activities, interzonal airflows, and physical properties of bioaerosols can substantially impact the infection transmission risk. Further, the dominant pathway for influenza transmission indoors under most conditions was airborne transmission. Finally, estimations of the back-calculated quanta generation rate for influenza viruses were directly in line with the existing data gathered from prior epidemiology studies.
Ph.D. in Environmental Engineering, December 2016
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Title: Incorporating the Structure of Tall Buildings within an Architectural Form Generation Process
Creator: Almusharaf, Ayman M.
Date: 2011-05-04, 2011-05
Description: Traditionally, the development of tall buildings’ forms was a direct product of a close and meaningful collaboration between the architect and...
Show moreTraditionally, the development of tall buildings’ forms was a direct product of a close and meaningful collaboration between the architect and structural engineer. This was particularly evident in Chicago during the Modern Era in the architectural design of tall buildings, which provided the key ingredient of architectural form–structure interaction. The quest for iconic, individualistic forms during the Postmodern Era, however, has led to the shift away from the traditional format. New approaches to design began to overemphasize aesthetics and style while paying less attention to structure and the rigorous discipline it requires. In such approaches, issues pertaining to structure are typically addressed after the fact – that is, after the architectural form is well articulated – which necessarily limits the structural design role to solving the problem rather than integrating the structural solution into the architectural concept. This has resulted in an apparent disconnect between architectural form and structure in contemporary tall buildings. To address this disconnect, this research proposes a methodological digitallybased design approach that permits direct and concurrent interaction between the structural and formal design considerations pertaining to tall buildings during the conceptual design phase. Such an approach builds on the generative capabilities offered by available parametric/associative systems and the added potential of integrating them with structural analysis and evaluation tools. Through such integration, a performance feedback loop has been initiated to guide the iterative, parametric form development. Demonstration of the design approach has been carried out based on a number of design scenarios. Such demonstration illustrated the tool’s potential for assisting architects in realizing their conceptual ideas not only visually, but also structurally and materially. The process developed in this research yields architectural forms that respond positively to structure without in any way jeopardizing the visual intent of the architectural concept. The research concludes by remarking on the validity of the proposed approach, highlighting the research’s achievements, addressing the research’s limitations, and proposing directions for future research.
Ph.D. in Architecture, May 2011
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Title: REGENERATIVE POTENTIAL OF HUMAN CD34+ STEM CELLS MOBILIZED AND ENRICHED FROM BONE MARROW
Creator: Cohen, Amy
Date: 2014, 2014-12
Description: This thesis provides an in-depth investigation of the heterogeneous population of CD34+ cells obtained through granulocyte-colony stimulating...
Show moreThis thesis provides an in-depth investigation of the heterogeneous population of CD34+ cells obtained through granulocyte-colony stimulating factor (G-CSF) mobilization, apheresis, and an immuno-magnetic selection process. The results provide a better understanding of the phenotypic characteristics, functional migratory capabilities and paracrine secretory performance when exposed to normal and low-oxygen environments in vitro. The overall composition of the population acquired through the cells selection process and the CD34+ cells were characterized for maturity and commitment to various cell types as well as their potential for migration, adhesion and proliferation. The detailed phenotypic characteristics included positivity for more primitive, undifferentiated hematopoietic stem cells (HSCs) as well as markers indicating enrichment of long term HSCs. A functional quantitative bioassay was used to measure the migratory ability of the CD34+ cells. On average, 18.7% of the CD34+ cells migrated after 3 hours of incubation in the presence of 200ng/mL of Stromal Cell-Derived Factor One alpha (SDF-1α) as compared to 0.6% of the CD34+ cells incubated without chemoattractant. The migration was successfully neutralized by using monoclonal antibodies to CXCR4 and a CXCR4 antagonist, AMD3100. An evaluation of the migratory cell population showed that the cells exhibited an enhanced commitment to a monocyte or lymphocyte lineage and a larger percentage were CXCR4+. CD34+ cells were incubated in normoxic and hypoxic conditions and the proliferation, viability, immunophenotypic profile, migratory potential and secreted cytokines were evaluated and compared to incubation in normoxic conditions. The CD34+ cells proliferated in both the normoxic and hypoxic conditions over three days of incubation. The proliferation was higher in the hypoxic condition after one day of incubation, but after three days of incubation the normoxic conditions resulted in more proliferation. An increase in CD164 and a decrease in CD99 in the Day 3 hypoxic condition suggest that hypoxia was stimulating an adhesion pathway and suppressing the functional migration of the CD34+ cells. The three hour hypoxia incubation resulted in a significant (63%) reduction in the migration of the CD34+ cells as compared to the 3 hour normoxia condition, but many of the cells continued to migrate in hypoxia over the 24 hour period while the normoxic cells continued to migrate, but at a much slower rate. Culture media from CD34+ stem cells that had been incubated in normoxic or hypoxic conditions for one day and three days was assayed for sixty cytokine proteins known for possessing angiogenic qualities. Twenty five angiogenesis cytokines were increased in the culture media incubated with CD34+ cells, including tissue inhibitor of metalloproteinases-1 and 2 (TIMP-1 and TIMP-2), angiopoietin-1 (ANG-1) and insulin-like growth factor-1 (IGF-1). Thirteen angiogenesis cytokines were elevated in hypoxia as compared to normoxia, including TIMP-1, IGF and growth-regulated oncogene-β (Gro-β).
Ph.D. in Biological and Chemical Sciences, December 2014
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Title: CLONING, EXPRESSION, PURIFICATION AND STRUCTURE DETERMINATION OF PEANUT ALLERGEN ARA H 5
Creator: Wang, Yang
Date: 2012-11-21, 2012-12
Description: In our study, the peanut allergen Ara h 5 was cloned from raw peanut mRNA. The cDNA of the gene was then introduced into different expression...
Show moreIn our study, the peanut allergen Ara h 5 was cloned from raw peanut mRNA. The cDNA of the gene was then introduced into different expression vectors for protein expression in different E.coli strains. Recombinant protein expression was very successful with useful amounts of soluble protein produced. Fast protein liquid chromatography was used to purify the recombinant Ara h 5. High purity protein was subjected to crystallization screen and good quality crystals were harvested. Several crystallographic data sets were collected at a synchrotron X-ray beam line. The three-dimensional structure of the peanut profilin Ara h 5 was determined to 1.10Å resolution. The purified protein and the purification methods can be used in future research on the protein’s allergenecity, cross-reactivity and allergy immunotherapies. The high resolution structure was compared with the structures of homologous allergens and the putative epitopes was displayed on the allergen structure to evaluate their possible legitimacies. In the future, the Ara h 5 structure could be very valuable in studies of allergenecity and in the design of future immunotherapies.
PH.D in Biology, December 2012
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Title: DOES THE NEGATIVELY-WORDED ITEM EFFECT EXIST IN PERSONALITY MEASURES? A META-ANALYSIS
Creator: Huang, Jialin
Date: 2015, 2015-05
Description: This study meta-analyzed IRT item discrimination parameter estimates and CFA item loadings to explore the methodological effect of negatively...
Show moreThis study meta-analyzed IRT item discrimination parameter estimates and CFA item loadings to explore the methodological effect of negatively-worded items in personality measures. We found three important moderators that determined whether the negatively-worded item effect affected a scale. The first moderator was the manner in which the scale was defined. We found a strong negatively-worded item effect for Neuroticism but not for Emotional Stability. The personality scale was also a moderator, with a negatively-worded item effect being observed for Agreeableness, Extraversion, Neuroticism, and Openness but a positively-worded item effect for Emotional Stability and Conscientiousness. Third, low-motivation samples tended to produce a larger negatively-worded item effect. Moreover, there was no statistically significant difference between personality and non-personality inventories regarding the negatively-worded item effect. Finally, item negation did not produce the expected effect. Practical implications and limitations of the study are discussed.
Ph.D. in Psychology, May 2015
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Title: THERMO-RESPONSIVE HYDROGELS FOR INTRAVITREAL INJECTION AND BIOMOLECULE RELEASE
Creator: Drapala, Pawel
Date: 2011-04-20, 2011-05
Description: In this dissertation, we develop an injectable polymer system to enable localized and prolonged release of therapeutic biomolecules for...
Show moreIn this dissertation, we develop an injectable polymer system to enable localized and prolonged release of therapeutic biomolecules for improved treatment of Age-Related Macular Degeneration (AMD). Thermo-responsive hydrogels derived from N-isopropylacrylamide (NIPAAm) and cross-linked with poly(ethylene glycol) (PEG) poly(L-Lactic acid) (PLLA) copolymer were synthesized via free-radical polymerization. These materials were investigated for (a) phase change behavior, (b) in-vitro degradation, (c) capacity for controlled drug delivery, and (d) biocompatibility. The volume-phase transition temperature (VPTT) of the PNIPAAm-co-PEG- b-PLLA hydrogels was adjusted using hydrophilic and hydrophobic moieties so that it is ca. 33 C. These hydrogels did not initially show evidence of degradation at 37 C due to physical cross-links of collapsed PNIPAAm. Only after addition of glutathione chain transfer agents (CTA)s to the precursor did the collapsed hydrogels become fully soluble at at 37 C. CTAs signi cantly a ected the release kinetics of biomolecules; addition of 1.0 mg/mL glutathione to 3 mM cross-linker accelerated hydrogel degradation, resulting in 100 % release in less than 2 days. This work also explored the e ect of PEGylation in order to tether biomolecules to the polymer matrix. It was demonstrated that non-site-speci c PEGylation can postpone the burst release of solutes (up to 10 days in hydrogels with 0.5 mg/mL glutathione). Cell viability assays showed that at least two 20-minute bu er extraction steps were needed to remove cytotoxic elements from the hydrogels. Clinically-used therapeutic biomolecules Lucentis® and Avastin® were demonstrated to be both stable and bioactive after release form PNIPAAm-co-PEG-b-PLLA hydrogels. The thermo-responsive hydrogels presented here o er a promising platform for the localized delivery of proteins such as recombinant antibodies.
Ph.D. in Chemical and Biological Engineering, May 2011
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Title: MULTIFUNCTIONAL BIOMATERIAL SYSTEM FOR DRUG DELIVERY AND SCAFFOLDING TO PROMOTE NEOVASCULARIZATION IN TISSUE ENGINEERING
Creator: Jiang, Bin
Date: 2013, 2013-05
Description: The successful development of engineered tissues requires extensive vascular network formation. The overall goal of this work is to develop a...
Show moreThe successful development of engineered tissues requires extensive vascular network formation. The overall goal of this work is to develop a multifunctional biomaterial system for scaffolding and drug delivery to promote neovascularization in engineered tissue. Firstly, a drug delivery system was developed for molecules of different properties. Poly(lactic-co-glycolic acid) (PLGA) was prepared into microspheres using a double emulsion process for delivery of hydrophobic chlorhexidine (CHX) and hydrophilic platelet-derived growth factor-BB (PDGF-BB). Both drugs exhibited bioactivity after release and the efficacy of dual drug delivery was evaluated with an infected wound animal model. The simultaneous delivery of CHX and PDGF-BB improved wound healing and neovascularization while reducing bacteria levels. Therefore, the PLGA microspheres can be used for long-term active delivery of both hydrophobic and hydrophilic molecules in tissue engineering applications. Secondly, a 3D scaffold was developed for tissue engineering applications. Poly(ethylene glycol) (PEG) hydrogels with interconnected pores were generated with a salt leaching technique. Fibrin was filled in the pores by adding fibrinogen solution to hydrogel scaffolds pre-loaded with thrombin. The hydrogels were evaluated in a rodent subcutaneous implant model, showing that tissue invasion with a higher vascular density occurred when the hydrogels were loaded with fibrin. This composite hydrogel supports vascularized tissue ingrowth, and thus holds potential for tissue engineering applications. Thirdly, approaches from the previous studies were combined to develop a multifunctional biomaterial system for tissue engineering scaffolding and sequential xi growth factor delivery. PLGA microspheres were incorporated into a fibrin loaded porous hydrogel, in which the PEG based scaffold was modified to allow controlled degradation via hydrolysis. Different growth factors were encapsulated in fibrin and PLGA microspheres to provide temporal control of delivery. Growth factors released with the appropriate sequence promoted stable and functional blood vessel formation. In conclusion, a multifunctional biomaterials system was developed to provide structural and mechanical support for tissue regeneration, as well as delivery of signals that stimulate neovascularization. The system holds great potential for tissue engineering applications. Future work will require the extensive collaboration from interdisciplinary fields towards the successful development of engineered tissue substitutes.
PH.D in Biomedical Engineering, May 2013
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Title: ASSESSMENT OF STRUCTURAL MATERIALS BY HIGH TEMPERATURE INSTRUMENTED INDENTATION
Creator: Gan, Bin
Date: 2012-12-03, 2012-12
Description: This is an ideal place for me to express my gratefulness to my Ph.D. advisor, Prof. Sammy Tin, who has offered me the financial support and...
Show moreThis is an ideal place for me to express my gratefulness to my Ph.D. advisor, Prof. Sammy Tin, who has offered me the financial support and tremendous freedom in doing research. From working with me through publications and thesis, mentoring me what constitutes a professional and high quality work, nurturing my patience, to giving me advice on how to deliver an insightful presentation, Prof. Tin puts his effort in helping me on every small step that I need to make, as I gradually become more experienced in research and start to make a few achievement along the way. I am deeply indebted to Prof. Tin’s vision, guidance and sustained support. I would like to thank Prof. Philip Nash, Prof. Sheldon Mostovoy and Prof. Sudhakar Nair for being the committee member of my thesis defense, and offering me so many invaluable suggestions. The indispensable help from Russ Janota, the faculty and staff in the MMAE department is acknowledged. The enjoyable interaction with Mengtao, Qizheng, Matt, and other TPTC friends helps me in various aspects. I would like to thank Dr. Hideyuki Murakami and Dr. Takahito Ohmura for hosting me in NIMS. The experience had broadened my horizon and tremendously enhanced my capabilities to conduct independent research. In addition, the research collaboration with Prof. Julia R. Greer and Dr. Robert Maass on freestanding Ni3Al nanoparticles is also fully acknowledged. Furthermore, I am grateful to Prof. Qiang Feng and Prof. Roman Nowak. Their constant support, encouragement, mentoring and nurturing have a profound influence on me. This thesis is dedicated to my beloved parents, Jinlong Gan and Yuxiang Lai, who have built the fortitude into my mind. I also thank my sisters, Liping Gan and Lihong Gan, for their sustained support. Their love and understanding enable me to have a peaceful mind that makes this study possible. I also feel grateful to the deep love and endless patience from Xiaomo Li and the support from her parents.
PH.D in Materials Science and Engineering, December 2012
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