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Title: ANALYZING REPRODUCING KERNEL APPROXIMATION METHODS VIA A GREEN FUNCTION APPROACH
Creator: Ye, Qi
Date: 2012-04-22, 2012-05
Description: In this thesis, we use Green functions (kernels) to set up reproducing kernels such that their related reproducing kernel Hilbert spaces ...
Show moreIn this thesis, we use Green functions (kernels) to set up reproducing kernels such that their related reproducing kernel Hilbert spaces (native spaces) are isometrically embedded into or even are isometrically equivalent to generalized Sobolev spaces. These generalized Sobolev spaces are set up with the help of a vector distributional operator P consisting of finitely or countably many elements, and possibly a vector boundary operator B. The above Green functions can be computed by the distributional operator L := P TP with possible boundary conditions given by B. In order to support this claim we ensure that the distributional adjoint operator P of P is well-defined in the distributional sense. The types of distributional operators we consider include not only di erential operators but also more general distributional operators such as pseudo-di erential operators. The generalized Sobolev spaces can cover even classical Sobolev spaces and Beppo-Levi spaces. The well-known examples covered by our theories include thin-plate splines, Mat´ern functions, Gaussian kernels, min kernels and others. As an application for high-dimensional approximations, we can use the Green functions to construct a multivariate minimum-norm interpolant s f;X to interpolate the data values sampled from an unknown generalized Sobolev function f at data sites X Rd. Moreover, we also use Green functions to set up reproducing kernel Banach spaces, which can be equivalent to classical Sobolev spaces. This is a new tool for support vector machines. Finally, we show that stochastic Gaussian fields can be well-defined on the generalized Sobolev spaces. According to these Gaussian-field constructions, we find that kernel-based collocation methods can be used to approximate the numerical solutions of high-dimensional stochastic partial differential equations.
Ph.D. in Applied Mathematics
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Title: AGENT-BASED MODELING OF ANGIOGENESIS WITHIN DEGRADABLE BIOMATERIAL SCAFFOLDS
Creator: Mehdizadeh, Hamidreza
Date: 2013, 2013-12
Description: The ability to promote and control blood vessel assembly in polymer scaffolds is important for clinical success in tissue engineering. Often,...
Show moreThe ability to promote and control blood vessel assembly in polymer scaffolds is important for clinical success in tissue engineering. Often, experimental studies are performed to investigate the role of scaffold architecture on vascularized tissue formation. However, experiments are expensive and time-consuming and synthesis protocols often do not allow for independent investigation of specific scaffold properties. Mathematical and computational representation of the relationship between scaffold properties and neovascularization facilitates studying the fundamental processes involved in vascularization of biomaterials and provides more profound understanding of the critical factors that affect this process. This understanding is critical for the design of new therapeutic approaches that could bridge the existing gap between current experimental techniques and the state of the art practical tissue regeneration approaches. Computational models allow for rapid screening of potential material designs with control over scaffold properties that is difficult in laboratory settings. In this work, a multi-layered, multi-agent framework is developed to model the process of sprouting angiogenesis within porous biodegradable tissue engineering scaffolds. Software agents are designed to represent endothelial cells, interacting together and with their micro-environment, leading to formation of new blood vessels that perfuse the scaffold. A rule base, derived from the experimental findings reported in the literature, or observed by our collaborators, governs the behavior of individual agents. Two-dimensional and three-dimensional scaffold models with well-defined homogeneous and heterogeneous pore architectures are designed and simulated to investigate the impact of various scaffold design parameters such as pore size, pore size distribution, interconnectivity, and porosity, as well as the degradation behavior of 2 the scaffolds, on vessel invasion and capillary network structure. Model parameters such as the speed of vessel sprouting or cell migration speed are adjusted based on independent results of in vivo vascularization of fibrin gels in the absence of a polymer scaffold. The effects of various characteristics of scaffold degradation are also investigated. Various scenarios are defined and simulation case studies are developed to investigate the effect of scaffold geometrical and structural properties on angiogenesis. The simulation results are compared with available experimental results of scaffold vascularization performed in our group and with relevant published literature data to validate the developed model. These results indicate that in general the rate of vascularization increases with larger pore size and higher interconnectivity and porosity scaffolds. Pores of larger size (160-270 μm) support rapid and extensive angiogenesis, however vascularizing deeper parts of the scaffolds still remains a challenge that requires more complex scaffold designs. The agent-based model can be used to provide insight into optimal scaffold properties that support vascularization of engineered tissues. The modeling framework developed provides a novel interface for convenient integration of new knowledge to the current computational models, making it possible to gradually increase the level of complexity and accuracy of the models as our knowledge about the underlying biological system advances. The simulation results help us better understand the complex interactions between the growing blood vessel network and a degrading scaffold structure, and identify the optimal combinations of geometric and degradation characteristics of tissue engineering scaffolds that support scaffold vascularization.
PH.D in Chemical Engineering, December 2013
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Title: INVESTIGATING THE MEDIATION OF HEMOGLOBIN PROTEINS IN NITRIFICATION AT LOW DISSOLVED OXYGEN CONDITIONS
Creator: Arnaldos, Marina Orts
Date: 2012-10-30, 2012-12
Description: Due to the high aeration and energy requirements of nitrifying activated sludge processes, there is great interest in developing biological...
Show moreDue to the high aeration and energy requirements of nitrifying activated sludge processes, there is great interest in developing biological nitrifying processes that operate efficiently under low dissolved oxygen (DO) conditions. In this framework, the present study has investigated the acclimation of ammonia-oxidizing communities (AOC) to low DO concentrations. Under controlled laboratory conditions, two sequencing batch reactors seeded with activated sludge from the same source were operated at high DO (near saturation) and low DO (0.1 mg O2/L) concentrations for a period of 385 days. Stable and complete nitrification at low DO after an acclimation period of approximately 140 days was demonstrated. Modeling of oxygen transfer and uptake behavior demonstrated the low DO reactor to achieve equal performance to the high DO reactor, when the latter is operated at design DO concentration (2 mg O2/L), with approximately 20 % improvement in aeration requirements and oxygen mass transfer efficiency. The effect of DO on AOC dynamics was evaluated using the 16S rRNA gene as the basis for phylogenetic comparisons and organism quantification. Ammonium consumption by ammonia-oxidizing archaea and anaerobic ammonia-oxidizing bacteria was ruled out in both reactors. Even though N. europaea was the dominant AOB lineage in both SBRs at the end of operation, this enrichment could not be linked to acclimation to oxygen-limited conditions. This finding challenges the hypothesis that low DO conditions select for ammonia-oxidizing lineages characterized by high oxygen affinities, and points to the alternative mechanism of a physiological change of a generalist nitrifying community. Acclimation brought about increased specific oxygen uptake rates and enhanced expression of a particular heme protein in the soluble fraction of the biomass in the low DO reactor as compared to the high DO reactor. The heme protein induced was determined not to be any of the enzymes playing a role in ammonia metabolism of ammonia oxidizing bacteria, including a soluble oxidase and soluble peroxidase of unknown function. Further molecular studies are required to verify the hypothesis put forward in this study that the heme protein detected is a hemoglobin.
PH.D in Environmental Engineering, December 2012
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Title: ELECTROCHEMICAL ANALYSIS OF ACTINIDES IN MOLTTIN SALTS
Creator: Tylka, Magdalena
Date: 2015, 2015-05
Description: In electrochemical studies, the measured parameter (potential, current, or charge) is related to the quantity of the analyte in the solution...
Show moreIn electrochemical studies, the measured parameter (potential, current, or charge) is related to the quantity of the analyte in the solution and therefore can serve as an analytical signal for concentration measurements. The aim of this work is to develop high precision, real-time, quantitative, electroanalytical measurements of the concentrations of actinide chlorices in molten salts for monitoring pyrochemical process. Possible reasons for discrepancies found in the literature among electrochemically-measured values have been identified and methods to improve their precision have been established. Specific procedures were developed to refine both experimental techniques and data analysis methods. By following these procedures, precise and reproducible measurements were obtained for U and Pu in LiCl/KCl eutectic at 500°C. The effect of varying concentration on the method was investigated. In particular, the applicability of the techniques at high concentration of the analyte is evaluated. In addition to this, samples containing more than one analyte are considered, and the development of a modified data analysis method, required for their quantitative analysis, is described. Comparison of results obtained from improved electroanalytical measurements, and inductively coupled plasma atomic emission spectroscopy (ICP-AES) analysis, are shown and discussed. In addition to this, analysis of current-time transients, following a potential step, provide fundamental information about nucleation and growth of actinides on inert electrodes from molten salts. The effect of different concentrations of electroactive species, the applied potential, and the material of the working electrode on nucleation parameters are examined and discussed.
Ph.D. in Chemical Engineering, May 2015
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Title: SMART GRID COORDINATION IN BUILDING HVAC SYSTEMS
Creator: Mendoza Serrano, David Israel
Date: 2013, 2013-12
Description: In the context of real time electricity pricing, energy consumption by Heating, Ventilation, and Air Conditioning (HVAC) systems is usually...
Show moreIn the context of real time electricity pricing, energy consumption by Heating, Ventilation, and Air Conditioning (HVAC) systems is usually heaviest when prices are at their highest. In order to reduce expenditure while adequately maintaining indoor comfort conditions, Economic Model Predictive Control (EMPC) policies can be implemented in conjunction with Thermal Energy Storage (TES). This equipment con guration allows the time-shift of chiller power consumption away from periods of high demand to periods of low energy cost. Overcoming the main drawbacks intrinsic to EMPC policies constitutes the initial focus of this work. The rst issue concerns the susceptibility of EMPC to disturbance prediction quality, as this algorithm relies on weather and electricity price forecasts to generate control actions. Thus, two gray box models of increasing complexity are developed to illustrate the fundamentals of disturbance forecasting with shaping lters. Additionally, two data driven models are also presented for comparison. The discussion is then expanded to forecasting quality based on the amount of information available, and proper economic evaluation of these scenarios with gray and black box models is performed. The second issue of interest is related to the susceptibility of EMPC to prediction horizon, since this methodology computes control actions based on a receding horizon framework. Usually, control policies that reduce expenditure the most also rely on relatively large horizon sizes. These implementations tend to result in considerable computational burden. While horizon size reductions are commonly used to lessen the associated computational needs, they also carry signi cant economic performance degradations. To solve this issue, a novel Economic Linear Optimal Control (ELOC) capable of enforcing constraints statistically is developed. Additionally, the ELOC feedback is used to generate a receding horizon formulation capable of enforcing point-wise-in-time constraints, termed constrained viii ELOC. This algorithm is virtually insensitive to horizon size while retaining and even surpassing the economic performance of EMPC. The third major achievement of this work is the development of an HVAC equipment sizing and optimization methodology. This goal is achieved through the implementation of a gradient search algorithm designed to predict returns on investment based on a net present value analysis. As part of this technique, the ELOC and constrained ELOC methodologies are expanded for equipment design. The successful implementation and convergence of this numeric optimization is illustrated with a case study.
PH.D in Chemical Engineering, December 2013
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Title: WIND TURBINE FARMS IMPACT ON POLLEN TRANSPORT DISPERSION PATTER S
Creator: Hsu, Chin Yu
Date: 2012-11-28, 2012-12
Description: Wind energy has become more and more popular because electricity generation by wind power brings much less environmental impacts than...
Show moreWind energy has become more and more popular because electricity generation by wind power brings much less environmental impacts than conventional energy generation using coal. Also, energy generated by wind power does not require expensive fuel imported from overseas. Since the land in between turbines is still cultivated for crops and grazing, it is important to know the potential interference of wind turbines with pollen transport and dispersion, or the possible change of patterns established for thousands of years. However, these issues have not been studied in the literature. The co-existence of conventional crops with genetically modified (GM) crops has become a subject of debate. In particular, pollen transfer from GM crops to non-GM crops might result in the introgression of transgenes into natural populations as maize is mainly wind-pollinated. This study thus reports and assesses a comprehensive method that estimates maize pollen transport in the presence of turbines to ascertain the potential for maize pollen transport. The study on the concentrations of maize pollen transport affected by the wind turbines considers different dispersion parameters given the additional mechanical turbulence introduced by the presence of operating wind turbines. For instance, the wind turbines can increase surface roughness which subsequently causes increased mechanical turbulence. A high mechanical turbulence subsequently reduces downwind concentrations because of the mixing higher and wider into the atmosphere, which dilutes the maize pollen plume with more clean air. This study compares maize hourly concentrations and ground level flux levels inside and outside a virtual maize flux in the presence and absence of operating wind turbines. Results from a 14-day simulation of maize transport xii with and without operating wind turbines indicate that each difference of corresponding concentration and flux levels is statistically significant. Likewise, patterns of maize pollen transport inside the farm with turbine effects are significantly different from those without turbine effects. Overall, the average maize pollen concentration inside the farm in the absence of turbine effects is about 5 times greater than the corresponding maize pollen concentration with turbine effects. The total mass of maize pollen released into the air is the same whether the wind turbines are present or not. The portion of maize pollen staying inside the farm, on the other hand, is influenced by turbulence. For instance, the increased surface roughness caused by the turbine effects will increase the mechanical turbulence. Because the high mechanical turbulence carries a large portion of maize pollen away from the farm, only a small portion of maize pollen stays inside the farm due to the high turbulence that lifts maize pollen into higher levels of flow where the wind speed is stronger. In contrast, without turbine effects, a small portion of maize pollen leaves the farm while most of it deposits on the ground much sooner than it would with turbine effects. Therefore, maize pollen concentration and ground level flux in the presence of turbine effects will be greater than they are without turbine effects at a relatively far distance from the farm.
PH.D in Environmental Engineering, December 2012
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Title: DEVELOPMENT OF PERMEABLE REACTIVE FILTER SYSTEMS (PRFS) FOR TREATMENT OF URBAN STORMWATER RUNOFF
Creator: Prabhukumar, Giridhar
Date: 2013, 2013-05
Description: Urban stormwater runoff is a major contributor of pollutants to nearshore beach water of Lake Michigan and other water bodies. Reduction of...
Show moreUrban stormwater runoff is a major contributor of pollutants to nearshore beach water of Lake Michigan and other water bodies. Reduction of pollutants levels to within safe limits in urban runoff from near shore areas by means of filtration using low-impact reactive multi-media systems is the subject of research in this dissertation. The key research issues addressed are the identification of effective filter materials and laboratory-scale testing of the selected materials for permeable reactive filter systems (PRFS) that are feasible for installation in urban environment. The focus was to evaluate different media materials for removal of total suspended solids (TSS), nutrients (nitrate and phosphate), heavy metals (Cd, Cr, Cu, Pb, Ni and Zn), polycyclic aromatic hydrocarbons (naphthalene and phenanthrene) and microbial (E. coli.) contaminants from stormwater runoff to levels below standard discharge criteria. Eight different media materials were initially selected, including calcite, anthracite coal, zeolite, sand, iron-oxide coated sand (IOCS), iron filings, perlite and biochar. Of these, calcite (C), zeolite (Z), sand (S) and iron filings (Fe0) were screened based on preliminary column experiment results and used for further studies. Physical and chemical characterization studies were carried out to understand the material properties. Contaminant attenuation studies with lab-scale column experiments for the four individual media materials (C, Z, S and Fe0) were conducted with synthetic stormwater solution containing all the aforementioned pollutants. Results showed that calcite and sand were efficient in TSS, nutrients and polycyclic aromatic hydrocarbons (PAHs) removal, zeolite was efficient for metals removal and the only material that was able to lower E. coli level to below its safe xv limit of 126 most probable number (MPN) per 100ml, and iron filings was efficient in nutrients and metals removal. Column experiments were also conducted with three mixed media compositions, C-Z-S, C-Z-Fe0 and C-Z-S-Fe0. The results indicated that a multi-media based filtration system can perform efficiently to treat a wide range of pollutants and runoff flow conditions. Finally, several conceptual designs for PRFS were proposed that are suitable for application at various urban locations.
PH.D in Environmental Engineering, May 2013
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Title: RELATIVE RECEIVER AUTONOMOUS INTEGRITY MONITORING FOR FUTURE GNSS-BASED AIRCRAFT NAVIGATION
Creator: Gratton, Livio Rafael
Date: 2011-05-15, 2011-05
Description: The Global Positioning System (GPS) has enabled reliable, safe, and practical aircraft positioning for en-route and non-precision phases of...
Show moreThe Global Positioning System (GPS) has enabled reliable, safe, and practical aircraft positioning for en-route and non-precision phases of flight for more than a decade. Intense research is currently devoted to extending the use of Global Navigation Satellite Systems (GNSS), including GPS, to precision approach and landing operations. In this context, this work is focused on the development, analysis, and verification of the concept of Relative Receiver Autonomous Integrity Monitoring (RRAIM) and its potential applications to precision approach navigation. RRAIM fault detection algorithms are developed, and associated mathematical bounds on position error are derived. These are investigated as possible solutions to some current key challenges in precision approach navigation, discussed below. Augmentation systems serving large areas (like the Wide Area Augmentation System (WAAS) covering the North American continent) allow certain precision approach operations within the covered region. More and better satellites, with dual frequency capabilities, are expected to be in orbit in the mid-term future, which will potentially allow WAAS-like capabilities worldwide with a sparse ground station network. Two of the main challenges in achieving this goal are (1) ensuring that navigation fault detection functions are fast enough to alert worldwide users of hazardously misleading information, and (2) minimizing situations in which navigation is unavailable because the user‟s local satellite geometry is insufficient for safe position estimation. Local augmentation systems (to be implemented at individual airports, like the Local Area Augmentation System or LAAS) have the potential to allow precision approach and landing operations by providing precise corrections to user-satellite range measurements. An exception to these capabilities arises during ionospheric storms (caused by solar activity), when hazardous situations can exist with residual range errors several orders of magnitudes higher than nominal. Until dual frequency civil GPS signals are available, the ability to provide integrity during ionospheric storms, without excessive loss of availability, will be a major challenge. For all users, with or without augmentation, some situations cause short duration losses of satellites in view. Two examples are aircraft banking during turns and ionospheric scintillation. The loss of range signals can translate into gaps in good satellite geometry, and the resulting challenge is to ensure navigation continuity by bridging these gaps, while simultaneously maintaining high integrity. It is shown that the RRAIM methods developed in this research can be applied to mitigate each of these obstacles to safe and reliable precision aircraft navigation.
Ph.D. in Aerospace Engineering, May 2011
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Title: CREDIT DERIVATIVES AND COUNTERPARTY CREDIT RISK UNDER VOLATILE MARKETS
Creator: Li, Dan
Date: 2012-11-20, 2012-12
Description: Both counterparty credit risk and credit derivatives have come under greater scrutiny under volatile markets especially after the 2007’s...
Show moreBoth counterparty credit risk and credit derivatives have come under greater scrutiny under volatile markets especially after the 2007’s credit crunch and the 2008’s global recession. This dissertation covers three essays topics that reflect different perspectives in credit derivatives and counterparty credit risk under volatile markets. In the first essay topic, we focuses on the modeling challenge after the 2007/2008 crisis in counterparty risks measurement by introducing a 4-factor model for simplicity with extensive comparison with a 2-factor model for both pre-crisis and post-crisis scenarios. Besides the correlation effects and basis risks concluded from the experimental results, those also implied the urgent needs for regulatory standardization (and transparency) for counterparty risk management (e.g. CVA, CSA, collateralization, etc.). Since CDS is one of the main hedging instruments for counterparty risks, therefore, we then tackle CDS in volatile market in our second essay topic. We will review some common practices in handling CDS since the standard bootstrapping failed using conventional JPM (2001). We will also examine the corresponding assumptions and limitations of the latest CDS standardization (ISDA (2009)). And we will compare this with the conventional CDS model. The third essay topic is a modeling survey on CDS with a special underlying – loan (LCDS) that unveils the potential usage and corresponding limitations of each prevailing modeling approach.
PH.D in Management Science, December 2012
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Title: FATIGUE AND BARKHAUSEN EFFECT
Creator: Tong, Wei
Date: 2013, 2013-05
Description: Piezomagnetism designates a change in the magnetization of materials induced by mechanical actions such as tension or compression. The type of...
Show morePiezomagnetism designates a change in the magnetization of materials induced by mechanical actions such as tension or compression. The type of Barkhausen effect that occurs in this work consists of sudden, discontinuous jumps in a material’s magnetization that appear in response to smooth (continuous) stress variations. A series of strain controlled fatigue tests with an alternating sinusoidal waveform were carried out to study the relationship between the endurance limit and the Barkhausen effect. Results of fatigue tests on steel specimens exhibiting Barkhausen pulses at various stages are reported and a threshold-crossing analysis is applied to the test results. These studies show that when the fatigue limit is approached, the Barkhausen pulses become, in general, more intense in amplitude and quantity than at other stress levels. A hypothetical mechanism is proposed that relates the intensity of the Barkhausen response to the inception of micro-cracking and rearrangements of the mechanical lattice at the microscopic level.
PH.D in Civil Engineering, May 2013
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Title: Combined Optimization Model for Sustainable Energization Strategy
Creator: Abtew, Mohammed
Date: 2011-04-01, 2011-05
Description: Access to energy is a foundation to establish a positive impact on multiple aspects of human development. Both developed and developing...
Show moreAccess to energy is a foundation to establish a positive impact on multiple aspects of human development. Both developed and developing countries have a common concern of achieving a sustainable energy supply to fuel economic growth and improve the quality of life with minimal environmental impacts. The Least Developing Countries (LDCs), however, have different economic, social, and energy systems. Prevalence of power outage, lack of access to electricity, structural dissimilarity between rural and urban regions, and traditional fuel dominance for cooking and the resultant health and environmental hazards are some of the distinguishing characteristics of these nations. Every year, 1.5 million people die due to exposure to indoor biomass stoves fumes. Rising demand for the decreasing supply of fuel wood is evident. Desertification is estimated to put 135 million people at a risk of being driven away from their land if no action is taken by 2020. Most energy planning models have been designed for developed countries' socio-economic demographics and have missed the opportunity to address special features of the poor countries. Therefore, it is critical to develop models that address the unique social-economic demographics of LCDs and are instrumental to appropriate energy policies choices. Such models must consider energization beyond electricity supply and help reduce over reliance of LCDs on limited energy sources that are fraught with high volatility and health hazard, thus providing a stable supply of energy that these countries badly need to meet their sustainable development goals. An improved mixed-integer programming energy-source optimization model is developed to address limitations associated with using current energy optimization models for LDCs, tackle development of the sustainable energization strategies, and ensure diversification and risk management provisions in the selected energy mix. The Model predicted a shift from traditional fuels reliant and weather vulnerable energy source mix to a least coast and reliable modern clean energy sources portfolio, a climb on the energy ladder, and scored multifaceted economic, social, and environmental benefits. At the same time, it represented a transition strategy that evolves to increasingly cleaner energy technologies with growth as opposed to an expensive solution that leapfrogs immediately to the cleanest possible, overreaching technologies.
Ph.D. in Management Science, May 2011
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Title: PROFESSIONAL AND TECHNICAL COMMUNICATIONS CONTRIBUTIONS TO STUDENT AFFAIRS WRITING COMPETENCIES
Creator: Schaefer, Kelly
Date: 2016, 2016-05
Description: Student affairs practitioners in mid-level positions write in the workplace daily, but in many cases they do not formally or intentionally...
Show moreStudent affairs practitioners in mid-level positions write in the workplace daily, but in many cases they do not formally or intentionally train themselves or their staff members to write. I used qualitative methods of semi-structured interviews, observations, and document analysis to investigate how and to what extent mid-level managers are competent writers. And in terms of their organizations, I investigated the value placed on writing and how and to what extent writing training happens. The investigation of writing practices of professionals working in campus centers in the field of student affairs shows that mid-level campus center professionals write extensively in their positions, including writing across many document types (letters, memos, reports, financial documents), and for multiple audiences in and outside of the university setting (students, staff, peers, supervisors, community members, alumni). Mid-level managers value writing ability and the ability of their staff members to be able to write, and could improve writing knowledge and ability through competency training and development by connecting with work in the field of professional communication. Professional associations can and should support professionals using competency language that supports writing and writing training to develop writing skill and ability competencies. Mid-level managers, as both writers and supervisors, could join associations in employing intentional strategies for writing and writing training suggested by professional communication research.
Ph.D. in Technical Communication, May 2016
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Title: SEISMIC STUDY OF HYBRID SHEAR WALL SYSTEM
Creator: Xu, Lifeng
Date: 2013, 2013-07
Description: This thesis represents the seismic behavior of new hybrid shear wall system, which consists of two exterior precast wall layers and one...
Show moreThis thesis represents the seismic behavior of new hybrid shear wall system, which consists of two exterior precast wall layers and one interior cast-in-place concrete layer. The “sandwich” shaped shear walls were already tested as a full scale specimen subjecting to vertical pressure and cyclic horizontal load in Anhui University of Architecture, China (2010). A series of 3D non-linear finite element models which include all significant details and specifications were then created in ABAQUS to simulate the experiments. The pushover analyses method was employed to reproduce the test procedures. The response of the structure was computed both at macro and micro level at the result in order to validate the correctness of the analytical model. After verifying the good agreement between the experimental observations and simulation results, an extended parametric study was conducted towards this hybrid shear wall system to explore its damage mechanism and design optimization. Based on hybrid shear wall's specific seismic resisting capacity which derived from the previous simulation, a series of 2D models were created in SAP2000 to evaluate the seismic performance of hybrid shear wall structure. What's more, in order to precisely represent the 3D model effect into 2D model in SAP2000,3D model was created in ABAQUS to account for the influence of semi-rigid connection between the concrete diaphragm and hybrid shear wall. After applying the ability of semi-rigid connection and hybrid shear wall, pushover method and time history analysis were conducted towards this 18 story structure model. The global seismic performance factor is finally evaluated according to the FEMA-P695.
PH.D in Civil Engineering, July 2013
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Title: MODELING GLUCOSE-INSULIN DYNAMICS AND AUTOMATED BLOOD GLUCOSE REGULATION IN PATIENTS WITH TYPE 1 DIABETES
Creator: Oruklu, Meriyan
Date: 2012-11-06, 2012-12
Description: Estimation of future glucose concentrations is a crucial task for diabetes management. Predicted glucose values can be used for early...
Show moreEstimation of future glucose concentrations is a crucial task for diabetes management. Predicted glucose values can be used for early hypoglycemic/hyperglycemic alarms or for adjustment of insulin amount/rate. In the first part of this thesis, reliable subject-specific glucose concentration prediction models are developed using a patient’s continuous glucose monitoring (CGM) data. CGM technologies provide glucose readings at a high frequency and consequently detailed insight into a patient’s glucose variation. Time-series analyses are utilized to develop low-order linear models from a patient’s own CGM data. Glucose prediction models are integrated with recursive identification and change detection methods, which enable dynamical adaptation of the model to inter-/intra-subject variability and glycemic disturbances. Two separate patient data sets collected under hospitalized (disturbance-free) and normal daily life conditions are used to validate the univariate glucose prediction algorithm developed. Prediction performance is evaluated in terms of prediction error metrics and Clarke error grid analysis (CG-EGA). The long-term complications of diabetes can be reduced by controlling the blood glucose concentrations within normoglycemic limits. In the second part of this thesis, the subject-specific modeling algorithm developed in part one is integrated with a control algorithm for closing the glucose regulation loop for patients with type 1 diabetes. An adaptive control algorithm is developed to keep a patient’s glucose concentrations within normoglycemic range and dynamically respond to glycemic challenges with automated subcutaneous insulin infusion. A model-based control strategy is used to calculate the required insulin infusion rate, while the model parameters are recursively identified at each sampling step. The closed-loop algorithm is designed for the subcutaneous route for both glucose sensing and insulin delivery. xii It accounts for the slow insulin absorption from the adipose tissue and the time-delay between blood and subcutaneous glucose concentrations. The performance of the control algorithm developed is demonstrated on two simulated patient populations to provide effective blood glucose regulation in response to multiple meal challenges with a simultaneous challenge on a patient’s insulin sensitivity. Physical activity and emotional stimuli such as stress are known to have a significant effect on a patient’s whole-body fuel metabolism. In the third part of this thesis, the univariate time-series models developed from recent glucose concentration history are extended to include additional information on a patient’s physical and emotional condition. Physiological measurements from a multi-sensor body monitor are used to supplement a patient’s CGM data and develop multivariate glucose prediction models. The prediction performance of the multivariate algorithm developed is evaluated on data collected from patients with type 2 diabetes, and a real life implementation of the algorithm is demonstrated for early (i.e., 30 min in advance) hypoglycemia detection. Finally, the control algorithm developed in part two is extended to utilize the glucose profiles predicted by the multivariate patient model. The multivariate closedloop algorithm is tested with two clinical experiments performed on a patient with type 1 diabetes during a high intensity exercise followed by a carbohydrate-rich meal challenge. The algorithm acquires the patient’s CGM and armband (body monitor) data every 10 min, and accordingly calculates the required basal insulin infusion rate. Insulin is administered in a fully automated manner without any food or activity announcements (e.g., no information on meal/exercise size or time). None of the algorithms developed in this thesis require any patient specific tailoring or prior experimental data before implementation. They are also designed to function in a fully automated manner and do not require any disturbance announcexiii ments or manual inputs. Therefore, they are good candidates for installation on a portable ambulatory device used in a patient’s home environment for his/her diabetes management.
PH.D in Chemical and Biological Engineering, December 2012
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Title: SIMULTANEOUS INJECTION OF STABLE AND RADIOACTIVE IONS INTO UPGRADED MULTI-USER ATLAS
Creator: Perry, Amichay
Date: 2015, 2015-12
Description: Argonne Tandem Linac Accelerator System (ATLAS) is a Department of Energy (DOE) national user research facility, located at Argonne National...
Show moreArgonne Tandem Linac Accelerator System (ATLAS) is a Department of Energy (DOE) national user research facility, located at Argonne National Laboratory (ANL). Presently, Radioactive Ion Beams (RIBs) produced in the CAlifornium Rare Isotope Breeder Upgrade (CARIBU) facility are charge bred in an Electron Cyclotron Resonance (ECR) charge breeder prior to post acceleration in ATLAS. A new state of the art Electron Beam Ion Source charge breeder, the CARIBU-EBIS charge breeder, has been developed (not in the scope of the work presented here) at ANL to replace the existing ECR for charge breeding RIBs generated in CARIBU. The CARIBU-EBIS charge breeder is now in the final stages of offline commissioning at the Accelerator Development Test Facility (ADTF). A significant part of the commissioning effort has been devoted to testing the source by breeding singlycharged cesium ions injected from a surface ionization source. Characterization of the CARIBU-EBIS performance has been accomplished through a comparison between the measured properties of extracted beams and simulation results. Following its offline commissioning, CARIBU-EBIS will be relocated to its permanent location in ATLAS. An electrostatic transport line has been designed to transport RIBs from CARIBU and inject them into CARIBU-EBIS. In addition, modifications to the existing ATLAS Low Energy Beam Transport (LEBT) were also required in order to transport the charge bred RIBs from CARIBU-EBIS to ATLAS. A proposal for upgrading ATLAS to a multi-user facility has been explored as well. In this context, beam dynamics simulations show that further modifications to the ATLAS LEBT will enable the simultaneous injection and acceleration of RIBs and stablebeams in ATLAS. Furthermore, a novel technique proposed by Ostroumov et al. will allow for the acceleration of multiple charge states from CARIBU-EBIS, thereby increasing the intensity of available RIBs by up to 60%.
Ph.D. in Physics, December 2015
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Title: SECURITY POLICY MANAGEMENT, THREAT ALLEVIATION AND TRUSTED PLATFORMS FOR EMBEDDED COMPUTING SYSTEMS
Creator: Anand, Vijay
Date: 2011-08, 2011-07
Description: Security guarantees are a measure of trust that can be placed on computing services in the safeguarding of digital assets. These security...
Show moreSecurity guarantees are a measure of trust that can be placed on computing services in the safeguarding of digital assets. These security goals and guarantees coupled with known and modeled threats to the digital assets shape the security policies for computing services. The creation, management and implementation of security policies in computing services is a challenge in defining the role of policy, the management principle for decision making when posed with threats and overall control over digital assets in a well-defined manner. In this Ph.D. thesis we establish a causal relationship of security policies with threats, provide an industry standard management framework (Six Sigma) for decision making, changes to the constructs of the trusted platform module to create a control framework and, finally show how the security framework can be used in a commercial service. The process of updating and refactoring security policy changes becomes a time consuming and tedious task, especially when threats evolve and computing service constructs change when security policy implementations are implicitly implemented. With the basis of correlation of policies over threats an explicit security policy implementation is proposed such that its adaptability, testability and risk quantification can be achieved when threats evolve. In this study we explore policy threat correlation on a Trusted Platform Module (TPM), a hardware system entrusted with security operations and guarantees. An effective TPM needs to adapt to evolving threats arising from firmware bugs or decay in the complexity of ciphering algorithms. Therefore, an adaptive TPM architecture is proposed to counter evolving threats by integrating an FPGA (Field Programmable Gate xi Arrays) block to alter and patch firmware and change ciphering systems. We present how security guarantees in an IT(Information Technology) infrastructure can be met using a TPM and thereby should be an integral part of computing services along with other security constructs like firewalls, intrusion detection systems, anti-virus, etc.. Adaptive security policy requires a management process wherein the risk management, and cost effectiveness principles can be identified. This is essential to make decisions on the trust criteria of digital assets in an industrial management framework. The security policy creation and management process presented in this thesis is based on Six Sigma model and presents a method to adapt security goals and risk management in an industrial framework. As an effective implementation of the security policy the case of application commerce workflow for developers is presented. Secure application distribution and execution guarantees lie in the transfer of trust between various processes in a computing service, also known as Chain of Trust in an embedded system. This study presents application development workflows facilitating secure commerce of digital assets thereby improving consumer trust.
Ph.D. in Computer Engineering, July 2011
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Title: MANAGING THE BIDDING PROCESS FOR THE CONSTRUCTION OWNER – DETECTION AND PREVENTION OF UNBALANCED BIDS AND COLLUSIVE BIDS
Creator: Chotibhongs, Ranon
Date: 2011-09, 2011-12
Description: There are two major problems that affect bidding efficiency: unbalanced bidding and collusive bidding. Unbalanced bidding is a serious...
Show moreThere are two major problems that affect bidding efficiency: unbalanced bidding and collusive bidding. Unbalanced bidding is a serious unethical problem in the construction industry. The owner may end up paying more money if the bid is unbalanced by the contractor. A bid can be rejected by the owner if it is unbalanced. A bidder unbalances a bid by inflating the unit price of some line items and reducing the unit price of other line items. Frontloading is the most common practice where a bidder can mathematically unbalance a bid by overstating the unit price of line items scheduled to be performed early in the project and understating the unit price of line items performed later. A bidder can also overstate the unit price of a line item whose quantity was somehow underrated by the engineer. If the owner proves that a mathematically unbalanced bid costs more to perform, the bid is said to be materially unbalanced, in which case the owner can reject the bid. A model is presented that formalizes and automates the process of detecting mathematically and materially unbalanced bids by comparing line item prices with the engineer’s estimates or the average prices offered by the bidders. This model allows owners to detect and reject unbalanced bids, and deters bidders from unbalancing their bid. Another matter that inflates bids and reduces bidding efficiency is collusion. Collusion is an insidious issue in the construction industry. Even though, it is widely acknowledged as unethical and illegal, there are not many research studies conducted to detect collusive bidding. This study proposes a two-step method to detect collusive bidding by analyzing historical bidding data provided by a construction owner. The construction owner in this study was a public agency that commissioned 108 construction projects that was worth $1.3 billion during a 10-year study period (2001-2010). The first step involves indentifying the potential cartel bidders using the residual test and the cost structure stability test developed in earlier work. The second involves comparing the behavior of the potential cartel bidders and non-cartel bidders by analyzing bid distributions, their cost dispersion, and the differences in their cost structures. After conducting the tests, it was found that the suspected cartel bidders identified in Step 1 behaved in ways to confirm collusion. Also, in an unrelated search, it was found that two of the six potential cartel bidders who were identified in this study had been audited by the public agency for bid fraud, and that another potential cartel bidder had been found guilty by the courts and forbidden from doing business with the public agency.
Ph.D. in Civil Engineering, December 2011
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Title: HOSPITAL FACILITY DESIGN: A GUIDE TO SPACE PLANNING FOR A NEW GENERAL HOSPITAL IN VIETNAM
Creator: Pham, Tuan Anh
Date: 2015, 2015-07
Description: Vietnam is a relatively small and populous developing country. Over the past several decades, the change in the country’s market economy and...
Show moreVietnam is a relatively small and populous developing country. Over the past several decades, the change in the country’s market economy and the population growth have greatly affected the lives, activities, and the demands for heath care as well as impacted the healthcare system. Since 1994, the time when the United States abolished the trade embargo against Vietnam, the economic development and the growth of the healthcare system in the country have been extraordinary. Even though substantial investment has been obtained from the Vietnamese government, limitations remain in the physical facilities in the healthcare system as well as in the facility design. Designing a new general hospital is a complicated process and requires a lot of attention and knowledge from a design team. Generally, the design process consists of two phases: a planning phase and a design phase. The planning phase is extremely important and will decide the success of the general hospital. G D Kunders, an Indian professional hospital administrator and a healthcare facility planner, has stated “Failing to plan is planning to fail” (Kunders 2004, 61). The main objective of this dissertation, “HOSPITAL FACILITY DESIGN: A GUIDE TO SPACE PLANNING FOR A NEW GENERAL HOSPITAL IN VIETNAM,” is to produce a guide that will be a reference source for the Vietnamese government to improve the current standard for hospital design. As a reference source, the proposed guide can be used as a tool to assist Vietnamese architects and other professionals in healthcare design areas in improving the quality of the hospital planning and design in Vietnam. This dissertation also aims to be a teaching reference source for architecture educators to use in their instruction at universities in Vietnam and a learning resource to help architecture students understand requirements for spaces in a general hospital as well as how a general hospital functions so they can better plan and design it. The proposed guide is set in an arrangement that can help educators and students without strong backgrounds in hospital design to easily understand how to plan a new general hospital. The research methods used in this dissertation are (i) document reviews, (ii) qualitative research based on Post-occupancy Evaluation (POE), and (iii) comparative analyses. The findings are used to create a guide to space planning for a new general hospital to use to improve the current Vietnamese standards, TCVN 4470: 2012, General Hospital - Design Standard, in hospital planning and design for Vietnam. This dissertation consists of eight chapters, which include Chapter 1 - Introduction, Chapter 2 - Literature Review, Chapter 3 - Problem Statement, Chapter 4 - Methodology, Chapter 5 - Data Analysis, Chapter 6 - Findings, Chapter 7 - A Guide to Space Planning for a New General Hospital in Vietnam, and Chapter 8 - Conclusion.
Ph.D. in Architecture, July 2015
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Title: SHORT AND ULTRASHORT-PULSED LASER-MATERIAL INTERACTIONS: MODELING AND COMPARISONS WITH EXPERIMENTS
Creator: Tao, Sha
Date: 2013, 2013-07
Description: Lasers have wide applications in numerous areas. Laser-based applications and technologies often involve certain types of laser-material...
Show moreLasers have wide applications in numerous areas. Laser-based applications and technologies often involve certain types of laser-material interactions, many of which have not been sufficiently understood. In this thesis, through the development of the corresponding physics-based models and the comparisons of modeling results with relevant experiments (when available), the laser-material interaction mechanisms during the following processes will be studied: i) laser ablation of semiconductors; ii) laser-material interactions inside microholes; and iii) laser-induced plasma evolution (more detailed conditions of the studied processes are given in the thesis). This research work is expected to improve the understanding of laser-material interaction mechanisms in the above investigated processes, which may provide information that is useful for the improvement of many related existing laser-based applications or technologies and for the development of novel ones.
PH.D in Mechanical and Aerospace Engineering, July 2013
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Title: EVALUATION OF THE EFFECTS OF VEGETATION AND GREEN WALLS ON BUILDING THERMAL PERFORMANCE AND ENERGY CONSUMPTION
Creator: Susorova, Irina
Date: 2013, 2013-05
Description: Urban development poses multiple problems, including environmental pollution, a reduction in biodiversity, and the disappearance of the...
Show moreUrban development poses multiple problems, including environmental pollution, a reduction in biodiversity, and the disappearance of the natural environment. Man-made environments and structures consume a large amount of limited natural resources through their extensive use of energy and materials. This research explored the use of vegetation in building facades as a potential solution to the problems of urban ecology and the excessive energy consumption in buildings. Vegetated facades have the ability to reduce building energy use, reduce the urban heat island effect, improve air quality, and increase the biodiversity of plants and animals in cities. The goal of this research was to evaluate the effects of plants on thermal performance and energy consumption of buildings by developing a thermal model of a building facade covered with a layer of plants. The developed mathematical model accounts for thermal physical processes in a vegetated exterior wall, including solar radiation, infrared radiative exchange between the facade and sky, the facade and ground, the facade and vegetation layer, convection to and from the facade, evapotranspiration from the plant layer, heat storage in the facade material, and heat conduction through the facade. The model calculates vegetated facade surface temperature and heat flux through the facade for multiple weather conditions, plant physiological characteristics, and facade properties. The model was validated with the results of a week-long experiment measuring the thermal properties of bare and vegetated facades on a building at the Illinois Institute of Technology campus. The experiment and subsequent sensitivity analysis demonstrated that a plant layer can effectively reduce the facade exterior surface temperature, daily temperature x viii fluctuations, exterior wall temperature gradient, and, as a result, provide as much additional thermal insulation to the facade as a 2.5 cm layer of expanded polystyrene insulation, depending on a range of plant parameters. The vegetated facade model was also used to analyze the reduction in energy consumption in generic office and residential thermal zones for multiple parameters. The simulations showed that energy reduction could be as high as 6.2% of annual total energy use and 34.6% of cooling energy use in residential thermal zones, depending on building characteristics, plant parameters, and climate zone. Overall, the vegetated wall model developed and validated herein provides a new tool for evaluating the impact of plant layers on facade thermal performance in existing buildings retrofitted with green walls and for designing green walls for optimal energy efficiency in new construction.
PH.D in Architecture, May 2013
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