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Title: GRAIN BOUNDARY ENGINEERING IN INCONEL 600
Creator: Li, Baishun
Date: 2013, 2013-12
Description: Grain Boundary Engineering (GBE) is a process consisting of deformation-anneal iterations that increase special boundaries, especially the...
Show moreGrain Boundary Engineering (GBE) is a process consisting of deformation-anneal iterations that increase special boundaries, especially the fraction of Σ3 boundaries, to improve material properties such as corrosion resistance, intergranular fracture resistance or ductility. In this work, Inconel 600 super alloy was chosen as the research material. Different levels of compression at various temperatures followed by a subsequent anneal were used on the Inconel 600 to investigate the respective Σ3 boundary fractions as a function of processing. Orientation Image Microscopy (OIM) was applied to scan, observe and analyze the microstructures of the samples before and after deformation. The work was aimed at investigating the effect of hot deformation on the Σ3 boundary fraction in Inconel 600 and understanding the mechanisms of Grain Boundary Engineering. The formation of twins was studied with emphasis on their formation following elevated temperature deformation.
M.S. in Material Science and Engineering, December 2013
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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: MECHANICAL PROPERTIES AND DEFORMATION MECHANISMS OF TERNARY γ-γ’-δ NICKEL-BASED SUPERALLOYS
Creator: Di Sciullo Jones, Alexander
Date: 2012-12-03, 2012-12
Description: The primary drive towards the continued development of nickel-based superalloys lies in the turbine industry, both for propulsion and power...
Show moreThe primary drive towards the continued development of nickel-based superalloys lies in the turbine industry, both for propulsion and power generative uses, where approximately 90% of such materials are used. The ongoing trend is to increase the temperature, increase the rotational speed, and decrease the weight of turbines to increase their efficiency. Thus, much of the improvement of the efficiency of these machines rests on what materials are available to the industry. This has led to the design of superalloys specifically tailored to withstand the varied and increasingly demanding properties of turbine parts. Turbine discs, as one such part, experience substantially lower temperatures than the turbine blades, thus the creep properties of materials to be used in such an application are not quite as important. However, in the drive to increase turbine rotation speed and reduce weight, the industry is looking for materials which can withstand higher stresses. It is with this goal in mind that the material focused on in this work, V204H, was designed. The material utilizes a novel, three-phase microstructure consisting of γ-γ’-δ rather than a conventional two-phase γ-γ’ microstructure. It has been theorized that the addition of δ precipitates, formed through the addition of niobium, will behave as a reinforcement phase as in a particulate composite. The material was also heavily alloyed to increase strengthening and improve creep behavior via the addition of elements which decrease diffusion rate and deter grain boundary damage. It was discovered that this material has a fourth phase between the γ’ precipitates, and this was identified using SAD to be γ”. Flow stress tests over a range of temperatures and creep tests, both performed in compression, were conducted. These properties were seen to be exemplary for use in a turbine disc. It was, however, found that such properties deteriorated when the testing was conducted in tension. This xv
M.S. in in Materials Science and Engineering, December 2012
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Title: MABC2 REGULATES CELLULAR AND MITOCHONDRIAL HEME CONTENT IN CARDIOMYOCYTES
Creator: Khechaduri, Arineh
Date: 2011-04-20, 2011-05
Description: mABC2 (ABCB10) protein is a mitochondrial inner-membrane ATP-binding cassette transporter. The structure of mABC2 is similar to that of ABCB8 ...
Show moremABC2 (ABCB10) protein is a mitochondrial inner-membrane ATP-binding cassette transporter. The structure of mABC2 is similar to that of ABCB8 (mABC1), which was shown to export iron from mitochondria into the cytoplasm. Based on the structural similarities we hypothesized that mABC2 is involved in export of heme from mitochondria into the cytoplasm for subsequent use in cytosolic enzymes. To study the role of mABC2 in cellular and mitochondrial iron homeostasis, we modulated the expression of the protein in neonatal rat cardiomyocytes (NRCM). We found that downregulation of mABC2 led to significant decrease in total cellular heme content. There was a trend toward increase in total cellular heme content with overexpression of mABC2, however the finding was not statistically significant (p=0.36). To measure mitochondrial heme content with mABC2 modulation we have successfully isolated mitochondria from NRCM. Overexpression of mABC2 significantly elevated mitochondrial heme content. It has been shown that mABC2 and mitoferrin-1 (Mfrn1) interact and form an oligomeric complex with ferrochelates to enhance mitochondrial iron importation for heme biosynthesis. Our findings are inconsistent with the proposed function of mABC2 in heme export out of the mitochondria, but support the hypothesis that mABC2 modulates heme synthesis via regulation of stability and activity of Mfrn1 and ferrochelatase in cardiomyocytes. This suggests that mABC2 may play a role in regulation of cellular iron homeostasis by regulating expression of cellular iron import and/or export.
M.S. in Biology, May 2011
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Title: SUPERVISED AND INTERACTIVE IMAGE SEGMENTATION TECHNIQUES WITH AN APPLICATION TO PROSTATE CANCER
Creator: Artan, Yusuf Oguzhan
Date: 2013, 2013-05
Description: Prostate cancer is a leading cause of cancer death for men in the United States. Fortunately, the survival rate for early diagnosed patients...
Show moreProstate cancer is a leading cause of cancer death for men in the United States. Fortunately, the survival rate for early diagnosed patients is relatively high. Accurate prostate cancer localization with noninvasive imaging using MRI can be used to guide biopsy, radiotherapy, and surgery as well as to monitor disease progression. However, in general, a single type of MRI is not sufficient for reliable tumor localization. As an alternative, multispectral MRI, i.e., the use of multiple MRI-derived datasets, has emerged as a promising noninvasive imaging technique for the localization of prostate cancer; however almost all studies are with human readers. There is a significant inter and intra-observer variability for human readers, and it is substantially difficult for humans to analyze the large dataset of multispectral MRI. To solve these problems, this thesis presents various novel supervised and semi- supervised (interactive) segmentation techniques. Initially, we develop a supervised segmentation method by combining conditional random fields (CRF) and support vector machines (SVM) with a cost-sensitive framework, and show that proposed method further improves classical and cost-sensitive SVM results by incorporating spatial information. Next, we propose an extension of popular semi-supervised seg- mentation method, namely random walker (RW) algorithm, with automated seed initialization for multispectral MRI images. We also present an automated shape and boundary based segmentation approach for prostate segmentation from T2-weighted MRI. Proposed method is based on a banded geocuts algorithm that utilizes bound- ary and shape information to yield prostate segmentation. Finally, we develop a novel method that has the ability to design classifiers obtained from one imaging protocol and/or MRI device to be used on a dataset from another protocol and/or imaging device. In order to evaluate the performance of the proposed methods, we utilize multispectral MRI datasets acquired from 21 biopsy-confirmed cancer patients. Our results show that multispectral MRI helps to increase the accuracy of prostate cancer xiv localization when compared to single MR images; and that using advanced proposed methods for prostate cancer localization performs better than available methods in the literature.
PH.D in Electrical Engineering, May 2013
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Title: MATHEMATICAL MODELING AND ANALYSIS OF WASTEWATER TREATMENT PROCESSES
Creator: Raju Ganesan, Arun Kumar
Date: 2013-04-25, 2013-05
Description: The activated sludge process is the most commonly used biological waste water treatment system. Mathematical modeling of this process is...
Show moreThe activated sludge process is the most commonly used biological waste water treatment system. Mathematical modeling of this process is important for improving its treatment efficiency and thus the quality of the effluent released into the receiving water body. These models can help the operator predict the performance of the plant to take cost-effective and timely remedial actions that would ensure consistent treatment efficiency and meeting discharge requirements. However, due to the highly complex and non-linear characteristics of this biological system, mathematical modeling of this treatment process has remained a challenge. The first part of this study is to build fundamental grey-box models to predict the raw influent quality and the preliminary effluent of the plant for any given day using historical data. The thesis is an attempt to model the various waste water treatment processes and validate the model with the historical data available for the Stickney Water Reclamation Plant, Chicago. This model has been further used to analyze the plant on both dry and wet weather conditions. Wastewater treatment processes utilize approximately 3% of the energy consumption in the US. A detailed study of the aeration required for the activated sludge tanks has been performed. The plant has been operated at a far higher aeration compared to the minimum required aeration which has increased the operating costs tremendously. A description of cost reduction by minimizing aeration usage without compromising on the discharge limits has been provided. Finally, storms are one of the biggest challenges faced by the operators in treatment plants. Dynamic simulations of storms have been described using the model to understand and control storm events in a more robust manner.
M.S. in Chemical Engineering, May 2013
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Title: VALIDATION AND CHARACTERIZATION OF TURBULENCE IN AN AORTIC COARCTATION
Creator: Arzani, Amirhossein
Date: 2012-04-25, 2012-05
Description: Image based, patient speci c computational uid dynamics (CFD) modeling has gained dramatic attention in evaluation of health and disease...
Show moreImage based, patient speci c computational uid dynamics (CFD) modeling has gained dramatic attention in evaluation of health and disease progression. With the popularity of these techniques in clinical settings the need to address how these numerical predictions validate against the empirical data becomes more imperative. Validation studies have primarily been used in vitro models, since experiments are dif- cult to control in vivo, and in vivo conditions are challenging to replicate numerically. However, in vivo validations are essential for a more reliable assessment. Moreover, direct quanti cation of turbulence, necessary for diagnostic purposes, makes the validation process more challenging in turbulent ows. A phase-contrast magnetic resonance imaging (PCMRI) method was used to obtain turbulent kinetic energy (TKE) in an aortic coarctation, a congenital disease, where the aorta narrows blocking the passage of blood to a great portion of the body. A 3D patient-speci c computer model of the aortic coarctation was constructed from the MRI data. Direct numerical simulation was performed to solve the Navier-Stokes equations using a stabilized nite element method. Based on the PCMRI procedures, di erent methods were used to compute TKE from the CFD velocity data, and were compared to the PCMRI data. The velocity data obtained from CFD was also used to study the ow topology by computing the Finite-Time Lyapunov Exponent (FTLE) eld, and the Lagrangian coherent structures (LCS). The TKE results showed relative good agreement between the in vivo measurements and the CFD predictions of TKE. Observed di erences were within expectations due to modeling, measurement and numerical errors.
M.S. in Mechanical, Materials, and Aerospace Engineering, May 2012
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Title: A TASK-BASED APPROACH TO PARAMETRIC IMAGING WITH DYNAMIC CONTRAST-ENHANCED MRI
Creator: Haleem, Muhammad Salman
Date: 2011-07-28, 2011-07
Description: In this thesis, we propose a task-based approach to parametric imaging with dynamic image sequences and apply the proposed method to an...
Show moreIn this thesis, we propose a task-based approach to parametric imaging with dynamic image sequences and apply the proposed method to an example problem of prostate cancer segmentation with dynamic contrast enhanced Magnetic Resonance Imaging (DCE MRI). Traditionally, the time activity curve obtained from dynamic series of MR images is modeled without considering a specific task in order to obtain the kinetic parameters and to construct the parametric images. This mostly consists of estimating parameters based on minimizing the error between the model and measurement. Unfortunately, this method results in noisy images and performances of the task in hand e.g. tumor segmentation suffers. Therefore, we develop a new method for the estimation of kinetic parameters based on the maximization of tumor segmentation performance. The kinetic parameters are estimated with a weighted approach such that the performance of the particular task is maximized. The mathematical criterions used to quantify the performance are Fisher Ratio, Area Under the Curve (AUC) and the Dice Measure. The proposed method of parametric imaging is tested with the problem of prostate cancer localization with DCE MRI. We use Linear Discriminant Analysis (LDA) as a segmentation tool and use quantitative measures to compare segmentation results, such as Fisher Ratio, Dice Measure, Sensitivity, Specificity and Area Under the Curve (AUC). Our results show that the proposed method is able to improve the prostate cancer localization for certain patients.
M.S. in Electrical Engineering, July 2011
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Title: Strategies for Improved Biodesulfurization in Genetically Engineered E.Coli Hosts
Creator: Ranganathan, Abhaya
Date: 2011-04-20, 2011-05
Description: Biodesulfurization has been an area of active research for the past few decades, in an effort to curb the amount of sulfur byproducts released...
Show moreBiodesulfurization has been an area of active research for the past few decades, in an effort to curb the amount of sulfur byproducts released into the environment. One key aspect of sulfur removal using biological techniques is the microbial conversion/utilization of dibenzothiopene (DBT), an ubiquitous component of organic sulfur compounds of crude oil. Three main enzymes are involved in 4S pathway of biodesulfurization; they are DszA, DszB, and DszC. DszD is a fourth enzyme that provides the necessary cofactors to Dsz A and DszC to complete their monooxygenase reactions in a number of bacteria with desulfurization capability, such as Rhodococcus erythropolis IGTS8. In this study, two ways to engineer bacteria, especially E. coli, for improved biodesulfurization of crude oil were investigated. The first was to express the dszD gene in E. coli in conjunction with the dszABC operon and study its effect on the growth pattern of the cells in minimal medium with DBT as the sole source of sulfur. The second approach was to clone the gene encoding sulpeptide S2, which is a sulfur-rich polypeptide, along with the desulfurization operon so that expression of sulpeptide would increase the demand for sulfur by the host cells. dszD and S2 were successfully cloned downstream of existing constructs of pGEM T-easy dszABC and pNW33N dszABCD and were expressed in E. coli strains BL21 and DH5α respectively. Growth experiments indicated marginal increase in the presence of dszABC compared to the unengineered strain and in the presence of dszD and S2; however, improved desulfurization activity was observed in the case of cells harboring dszD in addition to the dszABC operon.
M.S. in Biology, May 2011
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Title: A MASTER PLAN FOR A DETROIT NEIGHBORHOOD MADE IN DETROIT
Creator: Rios, Adriana Teresa
Date: 2014, 2014-05
Description: A MASTER PLAN FOR A DETROIT NEIGHBORHOOD MADE IN DETROIT Adriana Teresa Rios, M.S.Arch Illinois Institute of Technology, May 2014 Adviser: Tom...
Show moreA MASTER PLAN FOR A DETROIT NEIGHBORHOOD MADE IN DETROIT Adriana Teresa Rios, M.S.Arch Illinois Institute of Technology, May 2014 Adviser: Tom Brock Co-Adviser: George Schipporeit This thesis was written on behalf of the Sustainable New Cities program for the Illinois Institute of Technology. The goal of this Thesis is to establish a working definition of sustainability and the framework necessary for rebuilding a neighborhood in Detroit. The neighborhood in this Thesis being rebuilt is directly Southwest of Downtown Detroit. For the purpose of this thesis, sustainability is defined materially, socially, environmentally and economically. The plan for this Thesis is accomplished in phases to allow for an appropriately sized and conscientiously executed change. There is a large portion devoted to the history of Detroit and current state of the city; the reason for such an examination is to fully understand the past mistakes and successes throughout the history of Detroit. The systems and infrastructure designed in this Thesis effectively create a walkable thriving community that is diverse in it’s ecology, economy, and demographics. A major component for making this Thesis viable is the design of a Technology Campus that will collaborate with the city, local universities, and various technical companies to educate and train existing and new members of the local population. The second intergral aspect of this design is the light rail that will improve and simplify transportation outside of automobile traffic. Aside from the tangible infrastructure benchmarks, this Thesis also establishes the necessary theory behind a neighborhood that will continue to grow change and thrive. This Thesis has achieved a plan that considers all aspects of reconfiguring a neighborhood with sustainability as the focus.
M.S. in Architecture, May 2014
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Title: AN INTEGRATED FRAMEWORK FOR OPIMIZING TRAVEL TIME FOR CARS IN SMART CITIES
Creator: Al Hassan, Reida
Date: 2015, 2015-12
Description: This thesis proposes three different approaches for optimizing the travel time of cars in large networks. Genetic Algorithm with the...
Show moreThis thesis proposes three different approaches for optimizing the travel time of cars in large networks. Genetic Algorithm with the integration of microscopic traffic simulation is employed to search for global solution for traffic signals settings. Shortest path algorithms are utilized to regulate the congestion level of the network. Large networks are partitioned into subnetworks to enable the optimization and simulation procedure. Several case studies are analyzed in this thesis to examine the efficiency of each approach and to observe the influence of different factors in the solution quality and computation time of the optimization process.
M.S. in Electrical Engineering, December 2015
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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: RECRYSTALLIZATION MECHANISM FOR TWO NICKEL BASED SUPERALLOYS
Creator: Balandra, Ombeline
Date: 2016, 2016-05
Description: The demand for enhanced structural performances materials is growing every year. A lot of technological advancements in the sector of...
Show moreThe demand for enhanced structural performances materials is growing every year. A lot of technological advancements in the sector of aerospace or nuclear are in constant need for materials with good mechanical properties and high temperature resistance. The alloys commonly used for these features are Nickel-based superalloys as they exhibit high strength and good resistance to corrosion and oxidation. To improve their mechanical behavior, recent studies have focused on grain refinement methods. Among these methods to obtain the finest grain size distribution, one is particularly advantageous for it low cost and feasibility: severe plastic deformation.In this study, the deformation mechanism of two high performance, low stacking fault energy nickel-based alloys are investigated. The first alloy, Monel 400, it is a single FCC phase material. The second one is Inconel 625 wich has a two-phase (γ and γ’) microstructure. During hot deformation, the γ’ precipitate may be present in the γ phase and above a certain solvus temperature, the γ phase exists in the material. The restoration mechanism for FCC crystals is well known, and particular attention was given in this report to the recrystallization response and flow behavior of Inconel 625 for sub-solvus temperatures. In the introduction a brief review of the current state of literature on the deformation response of Nickel-based superalloys is provided. Samples were compressed under various temperatures and strain rate conditions using a Gleeble-3500 thermo-mechanical simulator and flow stress curves were extracted. To characterize both qualitatively and quantitatively the deformation, samples were then analyzed using standard microscopy, scanning electron microscopy and electron backscatter diffraction analysis. The resulting images and maps combined with flow stress curves have lead to the formulation of constitutive models of the recrystallization process using three parameters, the stress, grain size and recrystallized volume fraction.The data shows that deformation is first accommodated through dynamic recovery with the formation of sub-grains structures. Then, after the experimental strain reaches a critical value, recrystallized grains form within the microstructure. EBSD analysis show a trend for new recrystallized grain to grow under certain conditions. Results show a trend of increasing the grain size with increasing the strain and decreasing the Zener-Hollomon parameter and an increasing recrystallized volume fraction with increasing the strain and Zener-Hollomon parameter.
M.S. in Material, Mechanical and Aerospace Engineering, May 2016
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Title: ANALYSIS OF TRANSPORT TOPOLOGY IN THE LEFT VENTRICLE UNDER HEALTHY AND DISEASED STATES
Creator: Hendabadi, Sahar
Date: 2013, 2013-12
Description: There is evidence that under healthy conditions the vortical nature of blood in the LV optimizes pumping, yet precise characterization of...
Show moreThere is evidence that under healthy conditions the vortical nature of blood in the LV optimizes pumping, yet precise characterization of transport in the LV has been lacking. Because the ventricle is not completely emptied during ejection, blood entering through the mitral valve also interacts with residual ow from preceding cycles. The clinical and physiological consequences of these uid dynamics and interactions remain poorly understood in both healthy and diseased hearts. Simulation and imaging studies have aimed to understand the role of intraventricular ow dynamics to facilitate lling, increase ejection e ciency, and avoid blood stasis inside the ventricular chamber. Moreover, these three aspects may be of key importance in patients with heart disease, and most prevalently dilated cardiomyopathy (DCM). In this thesis, we used in vivo measurement of ow in healthy and diseased hearts. A novel processing of Doppler-echocardiography data was performed on patients with DCM and healthy volunteers. Bi-directional velocity eld maps in the apical long axis were obtained and used to perform Lagrangian analysis of transport inside the LV. Lagrangian coherent structures (LCSs) were shown to reveal the boundaries of blood injected and ejected from the heart over multiple beats. These boundaries were used to quantify stasis in the LV, which has potential clinical importance for diagnosing pumping de ciency and thrombosis risk. Indeed, we show that repelling LCSs, in addition to revealing a schematic of the transport topology, also identify structures in the ow that may potentially in uence platelet activation, which we demonstrate on an idealized stenosis model for simplicity. The LCS framework also enabled improved characterization of LV vortices, which had previously received much attention using Eulerian characterizations. The Lagrangian framework presented here uncovered well-de ned boundaries to both E-wave and A-wave lling vortices, which have not been previously quanti ed. To validate the utility xii of the planar ow approximation imposed by Doppler-echocardiography in enabling the dominant transport processes to be characterized, two di erent sets of 3D phase contrast magnetic resonance imaging (PCMRI) data were used to compare 3D ow analysis results with results derived from 2D projection of data in the long-axis. The validation results indicated that the main transport structures were preserved in 2D projections, especially during the ejection phase. Analysis of LV ow topology was also performed in patients undergoing cardiac resynchronization therapy (CRT). The results of this study can contribute to the optimization of AV delays in these patients by taking the LV transport into account. xiii
PH.D in Mechanical Engineering, December 2013
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Title: YAMUNA RIVER CITY: SUSTAINABLE NEW CITY NEW DELHI, INDIA
Creator: Aggarwal, Sakshi
Date: 2013, 2013-07
Description: The aim of this thesis is to design a sustainable city prototype with a new approach for a 100,000 residents in Delhi , India .This will give...
Show moreThe aim of this thesis is to design a sustainable city prototype with a new approach for a 100,000 residents in Delhi , India .This will give the ‘Delhiites‘ ( as we love to call ourselves ) a chance to live on the water body in a sustainable environment. To create this sustainable environment, the first challenge was to understand the site conditions, followed with the issues on the site, concept of developing new cities, reinforcing old sustainable technologies, and merging with new technologies for a better environmental, social and economic balance. Being on a flood plain, Delhi’s beautiful Yamuna river bed, was never built before, may be ignoring the fact that structure engineering has done some marvels in the past. Thus, I took up this challenge of building a city prototype here. It is hopeful that the design, ideas and process could also be a framework to be applied on other undeveloped land for new cities particularly in India and helps us to provide the solution for any foreseen problems in city development beforehand.
M.S. in Architecture, July 2013
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Title: THE BUSINESS CYCLE, FORECAST HORIZONS AND STOCK RETURN PREDICTABILITY
Creator: Irons, Robert
Date: 2012-12-04, 2012-12
Description: This paper investigates the impact of the business cycle when forecasting equity returns over different forecast horizons. Weigand and Irons ...
Show moreThis paper investigates the impact of the business cycle when forecasting equity returns over different forecast horizons. Weigand and Irons [2007] show that relative valuation matters when forecasting long-term returns to the market, a conclusion that is verified in this study with reference to the period 1934-1949. This study reveals that the business cycle matters when forecasting short-term (one year or less) market returns, over the entire period of study (1934-1999). An econometric issue first noted in Weigand and Irons [2008] is verified and pinpointed more precisely in time, to the year 1950. The market earnings yield (the inverse of the market P/E ratio), one of the foremost predictors of future market returns, is shown to be ineffective in forecasting returns over any forecast horizon in the second half of the 20th century. This result is further evidence of the impact of investors' belief in the Fed Model, which equates the yields on bonds to the returns on stocks. The term spread of interest rates, one of the business cycle proxies used in this paper, is shown to have a significant impact when forecasting market returns over any horizon during the period 1950-1999, which is consistent with the Fed Model.
PH.D in Management Science, December 2012
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Title: ASSESSING THE DIFFERENCES BETWEEN TEACHER AND CHILD PERCEPTIONS OF SOCIAL SKILLS
Creator: Roberts, Christina M.
Date: 2012-11-26, 2012-12
Description: This study examined the effects of group membership on the perception of social skills by comparing discrepancies between self-ratings and...
Show moreThis study examined the effects of group membership on the perception of social skills by comparing discrepancies between self-ratings and teacher-ratings of social skills. Given that differences between groups are typically controlled for, profile comparisons of this kind are scarce in the current literature. In this study, social skills of children in third, fourth, and fifth grades (N=108) were rated both by the children and by their teachers. Results from the analysis of the data, using discrepancy scores on the Social Skills Inventory System (SSIS), suggest that significant group differences only exist between ratings of Latino and African American children and ratings by their teachers. Additionally, no significant differences were observed when examining groups by gender, Piagetian stage, and by child age. Implications indicate that ethnicity affects teacher perception of social skills.
M.S. in Psychology, December 2012
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Title: HYBRID ELECTROSTATIC AND MICRO-STRUCTURED ADHESIVES FOR ROBOTIC APPLICATIONS
Creator: Ruffatto, Donald F., Iii
Date: 2015, 2015-07
Description: Current adhesives and gripping mechanisms used in many robotics applica- tions function on very speci c surface types or at de ned attachment...
Show moreCurrent adhesives and gripping mechanisms used in many robotics applica- tions function on very speci c surface types or at de ned attachment locations. A controllable, i.e. ON-OFF, adhesive mechanism that can operate on a wide range of surfaces would be very advantageous. Such a device would have applications ranging from robotic gripping and climbing to satellite docking and inspection/service mis- sions. The main goal of the research presented here was to create such an attachment mechanism through the use of a new hybrid adhesive technology. The newly devel- oped adhesive technology is a hybridization of electrostatic and micro-structured dry adhesion. The result provides enhanced robustness and utility, particularly on rough surfaces. There were challenges not only in the integration of these two adhesive elements but also with its application in a complete gripping mechanism. Electrostatic and directional dry adhesives were both individually investigated. The electrode geometry for an electrostatic adhesive was optimized for maximum ad- hesion force using nite element analysis software. Optimization results were then veri ed through experimental testing. New manufacturing techniques were also de- veloped for electrostatic adhesives that utilized a metalized mesh embedded in a sili- cone polymer and Kapton lm based construction, greatly improving adhesion. The micro-structured dry adhesive used was provided by Dr. Parness, from the NASA Jet Propulsion Lab (JPL), and consists of an array of vertical stalks with an angled front face, referred to as micro-wedges. The hybrid electrostatic dry adhesive (EDA) was created by fabricating the electrostatic adhesive directly on top of a dry adhesive mold. This process created an array of dry adhesive micro-wedges directly on the surface of the electrostatic adhesive. In operation the electrostatic adhesive provides a normal force which serves to pull the dry adhesive into the surface substrate. With greater surface contact more of the dry adhesive is able to engage, bring the electro-static adhesive even closer to the surface and increasing its e ectiveness. Therefore, the combination of these two technologies creates a positive feedback cycle whose whole is often greater than the sum of its parts. An interface mechanism is needed to transmit applied loads from a rigid struc- ture to the exiable adhesive while still maintaining its conformability. This is es- pecially important for strong adhesion on rough surfaces, such as tile and drywall. Di erent concepts such as a structured brillar hierarchy and a uid- lled backing pouch have been explored. Additionally, nite element analysis was used to evaluate di erent fribrillar shapes and geometry for the structured hierarchy. The goal was to equalize the load distribution across the adhesive while still maintaining surface compliance. A gripper mechanism was also created which used a servo for actuation and three rigid tiles with a directional dry adhesive. It was tested on a perching Micro Air Vehicle (MAV) as well as in the RoboDome facility at NASA's Jet Propulsion lab to simulate a satellite docking/capture maneuver.
Ph.D. in Mechanical and Aerospace Engineering, July 2015
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Title: BANDWIDTH ENHANCEMENT OF A COMPACT ANTENNA BY PARASITIC ELEMENTS
Creator: Celebi, Adem
Date: 2015, 2015-05
Description: Antenna structures are playing a major role in wireless systems, including communication systems, radars, satellite systems, information...
Show moreAntenna structures are playing a major role in wireless systems, including communication systems, radars, satellite systems, information networks and medical diagnostic systems. In these systems, external antennas are widely used, especially for devices with metallic enclosures. One of the common requirements for the ex- ternal antennas is the need for achieving small dimension while keeping the antenna performance optimized. In this respect, electrically small antennas (ESAs) are em- ployed. Realizing the design requirements of an ESA has been a challenge for antenna designers because some of the parameters such as large bandwidth and reasonably high input impedance are in conflict with the small antenna dimensions. A compact antenna with parasitic elements for bandwidth enhancement is proposed to address these issues for use with mobile devices. Loading the known antenna topologies with other structures could improve the design parameters such as gain, bandwidth, impedance, and beamwidth for antenna topologies which are impossible to achieve with the conventional antennas. In this respect, a parasitic element with a smaller scale is placed within the structure to obtain a second resonance close to the main antennas resonance for an increased bandwidth without increasing the overall dimen- sions of the antenna. This composite antenna is expected to have relatively high input impedances for each of the resonances, thus minimizing the need for an input matching network. A review of related prior work of antenna structures is presented to gain insight into the recent developments and methods in the field. The mini- mum quality factor (Q) and maximum gain of the ESA designs and their theoretical Antenna structures are playing a major role in wireless systems, including communication systems, radars, satellite systems, information networks and medical diagnostic systems. In these systems, external antennas are widely used, especially for devices with metallic enclosures. One of the common requirements for the ex- ternal antennas is the need for achieving small dimension while keeping the antenna performance optimized. In this respect, electrically small antennas (ESAs) are em- ployed. Realizing the design requirements of an ESA has been a challenge for antenna designers because some of the parameters such as large bandwidth and reasonably high input impedance are in conflict with the small antenna dimensions. A compact antenna with parasitic elements for bandwidth enhancement is proposed to address these issues for use with mobile devices. Loading the known antenna topologies with other structures could improve the design parameters such as gain, bandwidth, impedance, and beamwidth for antenna topologies which are impossible to achieve with the conventional antennas. In this respect, a parasitic element with a smaller scale is placed within the structure to obtain a second resonance close to the main antennas resonance for an increased bandwidth without increasing the overall dimen- sions of the antenna. This composite antenna is expected to have relatively high input impedances for each of the resonances, thus minimizing the need for an input matching network. A review of related prior work of antenna structures is presented to gain insight into the recent developments and methods in the field. The mini- mum quality factor (Q) and maximum gain of the ESA designs and their theoretical limitations are then discussed. The features of the antenna designs discussed in the review are used as foundation of the developed antenna structures. The properties and a fabrication method of the proposed antenna are then discussed. A commer- cially available software package based on finite element method is employed to aid in the antenna design. Several antenna prototypes are constructed to verify the design and the accuracy of the simulations. The prototypes are then tested using network analyzers and an RF anechoic chamber with the aim of characterizing the antenna performance in terms of antenna bandwidth and input impedance.
Ph.D. in Electrical and Computer Engineering, May 2015
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Title: 3D COMPRESSION ALGORITHMS AND SYSTEM-ON-CHIP DESIGN FOR ULTRASONIC IMAGING APPLICATIONS
Creator: Govindan, Pramod
Date: 2015, 2015-05
Description: Ultrasonic systems are widely used in imaging applications for nondestructive evaluation, quality assurance and medical diagnosis. These...
Show moreUltrasonic systems are widely used in imaging applications for nondestructive evaluation, quality assurance and medical diagnosis. These applications require large volumes of data to be processed, stored, and/or transmitted in real-time. Therefore, it is essential to compress the acquired ultrasonic radio frequency (RF) signal without inadvertently degrading desirable signal features. Signal fidelity, computational speed and resource utilization are the major parameters to be considered while designing the architecture for the compression algorithm. In this study, two algorithms for ultrasonic signal compression are analyzed based on: sub-band elimination using discrete wavelet transform; and decimation/interpolation using time-shift property of Fourier transform. Both algorithms offer high signal reconstruction quality with a peak signal-to-noise ratio (PSNR) between 36 dB to 39 dB for minimum 80% compression. The computational loads and signal reconstruction quality are examined in order to determine the best compression method in terms of the choice of DWT kernel, sub-band decomposition architecture and computational efficiency. Furthermore, for compressing a large amount of volumetric information, 3D compression algorithms are designed by utilizing the temporal and spatial correlation properties of the ultrasonic RF signals. The performance analysis indicates that the 3D compression algorithm presented in this study offers an overall 3D compression ratio of 95% with a minimum PSNR of 27 dB. Furthermore, the DWT based ultrasonic 3D data compression algorithm is implemented on a reconfigurable ultrasonic system-on-chip hardware platform targeted for real-time ultrasonic imaging applications. The reconfigurable platform allows analysis of multiple architectures to suit various applications. In this study, hardware andtemporal and spatial correlation properties of the ultrasonic RF signals. The performance analysis indicates that the 3D compression algorithm presented in this study offers an overall 3D compression ratio of 95% with a minimum PSNR of 27 dB. Furthermore, the DWT based ultrasonic 3D data compression algorithm is implemented on a reconfigurable ultrasonic system-on-chip hardware platform targeted for real-time ultrasonic imaging applications. The reconfigurable platform allows analysis of multiple architectures to suit various applications. In this study, hardware and software architectures of the 3D ultrasonic compression algorithm implemented on Xilinx Zynq all programmable system-on-chip platform are discussed, along with the analysis of computational performance. Both implementations provide a high signal compression ratio of about 98% with good quality signal reconstruction. This study demonstrates that, compressing 33 MBytes of experimental ultrasonic 3D data into 0.42 MBytes requires only 84 millisecond for hardware architecture, and one minute for software architecture, making both designs highly suitable for real-time ultrasonic imaging applications. Furthermore, the 3D compression is implemented by using OpenCL, which is adaptable to various platforms such as CPUs, GPUs and FPGAs. Therefore, OpenCL provides similar computational performance as that of hardware architecture, and the same flexibility as that of software implementation. This study demonstrates that the OpenCL implementation of ultrasonic 3D compression algorithm on Nvidia GT 750M graphical processing unit (GPU) completes the operation in less than one second.
Ph.D. in Electrical and Computer Engineering, May 2015
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