Search results

Title: DETECTION OF SUPEROXIDE ANION RADICALS IN ANION EXCHANGE MEMBRANE FUEL CELLS USING IN-SITU FLUORESCENCE SPECTROSCOPY
Creator: Zhang, Yunzhu
Date: 2016, 2016-07
Description: Anion exchange membrane (AEM) stability is a long-standing challenge that has limited the widespread development and adoption of AEM fuel...
Show moreAnion exchange membrane (AEM) stability is a long-standing challenge that has limited the widespread development and adoption of AEM fuel cells. It is essential to understand the mechanism of AEM degradation during fuel cell operation. There are multiple modes of AEM degradation, broadly classified as chemical, mechanical and thermal degradation. Chemical degradation is among the most destructive modes, and can be further sub-divided into nucleophilic degradation (induced by the hydroxide ion), and oxidative degradation (induced by reactive oxygen species). While the former has been extensively studied, there is minimal work on oxidative AEM degradation. The reactive oxygen chemical species produced during the operation of an AEM fuel cell have hitherto not been detected during operation. Given the high pH, it is postulated that superoxide anion radicals (𝑂2∙−), as opposed to hydroxyl radicals, are primarily involved in the degradation progress. The objective of this study was to confirm the 𝑂2∙− formation during AEM fuel cell operation and to monitor in real-time the rate of 𝑂2∙− generation in an operating fuel cell using in-situ fluorescence spectroscopy. 1,3-diphenlisobenzofuran (DPBF) was chosen as the fluorescence probe, the sensitivity of which towards 𝑂2∙− was evaluated by performing ex-situ experiments in a semi-batch reactor. We demonstrate that the fluorescence intensity of this dye selectively decreased upon exposing 𝑂2∙−. DPBF was then incorporated into an AEM (membrane was solution cast after mixing the dye with the casting solution), which was assembled into a fuel cell. 𝑂2∙− generation in an operating AEM fuel cell was then monitored via in-situ fluorescence spectroscopy using a bifurcated optical probe, when the cell was operated in H2/O2 mode. To confirm the impact of 𝑂2∙− on AEM degradation, independent experiments (without dye) were performed under identical conditions, under both H2/O2 and N2/N2 modes, and the ionic conductivity and ion exchange capacity were monitored to estimate degradation extent. From our in-situ fluorescence studies, we were able to estimate the rate constants and activation energy for oxidative AEM degradation in an operating AEM fuel cell.
M.S. in Chemical Engineering, July 2016
Show less

Title: BIG DATA SYSTEM INFRASTRUCTURE AT EXTREME SCALES
Creator: Zhao, Dongfang
Date: 2015, 2015-07
Description: Rapid advances in digital sensors, networks, storage, and computation along with their availability at low cost is leading to the creation of...
Show moreRapid advances in digital sensors, networks, storage, and computation along with their availability at low cost is leading to the creation of huge collections of data { dubbed as Big Data. This data has the potential for enabling new insights that can change the way business, science, and governments deliver services to their consumers and can impact society as a whole. This has led to the emergence of the Big Data Computing paradigm focusing on sensing, collection, storage, management and analysis of data from variety of sources to enable new value and insights. To realize the full potential of Big Data Computing, we need to address several challenges and develop suitable conceptual and technological solutions for dealing them. Today's and tomorrow's extreme-scale computing systems, such as the world's fastest supercomputers, are generating orders of magnitude more data by a variety of scienti c computing applications from all disciplines. This dissertation addresses several big data challenges at extreme scales. First, we quantitatively studied through simulations the predicted performance of existing systems at future scales (for example, exascale 1018 ops). Simulation results suggested that current systems would likely fail to deliver the needed performance at exascale. Then, we proposed a new system architecture and implemented a prototype that was evaluated on tens of thousands nodes on par with the scale of today's largest supercomputers. Micro benchmarks and real-world applications demonstrated the e ectiveness of the proposed architecture: the prototype achieved up to two orders of magnitude higher data movement rate than existing approaches. Moreover, the system prototype was incorporated with features that were not well supported in conventional systems, such as distributed metadata management, distributed caching, lightweight provenance, transparent compression, acceleration through GPU encoding, and parallel serialization. Towards exploring the proposed architecture at millions of node scales, simulations were conducted and evaluated with a variety of workloads, showing near linear scalability and orders of magnitude better performance than today's state-of-the-art storage systems.
Ph.D. in Computer Science, July 2015
Show less

Title: SYNTHESIS OF NANOPLATE STRUCTURES IN NI-BASED ALLOYS VIA DISCONTINUOUS PRECIPITATION
Creator: Zhou, Yang
Date: 2017, 2017-07
Description: Nanostructured materials are of increasing interest due to their potential for use in numerous applications including catalysis and filtration...
Show moreNanostructured materials are of increasing interest due to their potential for use in numerous applications including catalysis and filtration. Methods of synthesizing nanomaterials often include chemical techniques producing individual particles, which gives rise to issues of agglomeration and containment, and the processes are difficult to scale-up. This work is directed at addressing issues of the occurrence and kinetics of self-assembly and structural alignment of nanostructures, which involves the discontinuous precipitation transformation followed by selective dissolution. This synthesis method has been demonstrated using a Ni-49at.%Co-12at.%Al alloy. A complete discontinuous transformation in the Ni 49-12 alloy can be achieved in times as short as 30min. Thus, the large-scale production of such structures is feasible using conventional heat treatment facilities. The synthesis technique is generally applicable to any alloy system in which DP goes to completion and one phase can be selectively removed. The nanoplates are self-assembled, self-supported and well aligned if the precipitate is coherent with the matrix. In order to control the process it is necessary to understand the phase equilibria involving γ, γ′ and β phases in the Al-Co-Ni system. This has been investigated both experimentally and computationally. The isothermal sections at 1100°C and 800°C as well as a partial liquidus projection were determined which result in modifications to previously published work. Comparing the experimental results with the calculated results using Thermo-Calc (TCNI8), there is reasonable agreement. The predicted separation of the γ phase into a two-phase ferromagnetic and paramagnetic region has never been observed experimentally in this or other published work. Future work should explore the ferromagnetic and paramagnetic phase separation as predicted using Thermo-Calc to verify its occurrence in this system. The nanostructured material produced by complete DP transformation may have interesting mechanical properties and these have been studied to a limited extent in this work. The hardness tests show that with decreasing annealing temperature to 600°C, the hardness of certain samples increases significantly due to the precipitation of second phase. The tensile and creep properties of alloy samples with DP phase present were also investigated. The results imply that the occurrence of DP will have a favorable effect on the tensile strength of the sample while lowering the ductility at the same time. A method to generate serrated grain boundaries based on the DP transformation is proposed. Such structures are expected to increase the creep resistance. This was found to be the case in a limited temperature and loading range. Higher temperature or stress levels lead to DP occurrence and cause negative effects on the creep resistance compared to conventionally processed material. The Curie temperature in the Al-Co-Ni alloy system was also studied and determined using a combined magnetic TG and DSC method. A ternary contour map of the Curie temperature has been constructed. From the contour map, the Curie temperature was seen to decrease from high Co, low Al content samples to low Co, high Al samples bypassing a platform at mid Co content. A nonlinear surface fitting was made through a Exponential2D model, the function is helpful for the prediction of Curie temperature of γ phase in Al-Co-Ni alloy system. This method also provides a novel idea of detecting phase transformation and precipitation through thermo-magnetically analyzing the magnetic behavior of the alloys.
Ph.D. in Materials Science and Engineering, July 2017
Show less

Title: A STEP TOWARD SUPPORTING LONG-RUNNING APPLICATIONS WITH REAL-TIME CONSTRAINTS ON HYBRID CLOUDS
Creator: Wu, Hao
Date: 2017, 2017-05
Description: The advancement of computer and network technology has brought the world into a new computer cloud era. The ”pay-as-you-go” business model and...
Show moreThe advancement of computer and network technology has brought the world into a new computer cloud era. The ”pay-as-you-go” business model and the service oriented models allow users to have ”unlimited” resources if needed and free from infrastructure maintenance and software upgrades. Cloud services are currently among the top-ranked high growth areas in computing and are seeing an acceleration in enterprise adoption with the worldwide market predicted to reach more than $270b in 2020. According to Google, currently more than 95% of the web services are deployed on cloud.Many di↵erent types of applications are deployed on computer clouds. However, due to inherent performance uncertainty within computer clouds, as of today, applications with real-time and high QoS constraints still operate on traditional computer systems and are not able to benefit from elastic computer clouds.. The thesis focuses on both theoretical analysis and real system implementation on the problem of guaranteeing real-time application’s deadline requirement while minimizing the application’s execution cost on hybrid clouds. Four major problems have been addressed towards moving applications with real-time constraint on hybrid computer clouds. 1). A minimal slack time and minimal distance (MSMD) scheduling algorithm is developed to minimize the resources needed to guarantee an application’s end-to-end deadline requirement using computer clouds. 2). A VM Instance Hour Minimization (IHM) algorithm is developed to reduce the application’s execution cost for given schedules. The proposed IHM algorithm can be integrated with common scheduling algorithm used in the literature. In addition, we also evaluated the feasibility of utilizing spot instance to further reduce the application’s execution cost while not sacrificing QoS guarantees. 3). A reference model for virtual machine launching overhead is developed to predict both system utilization and timing overhead during the VM launching process. 4). A hybrid cloud management tool that integrates the developed algorithms and reference model is developed to support running long-running applications with real-time constraints on hybrid clouds.
Ph.D. in Computer Science, May 2017
Show less

Title: URBAN SPRAWL AND SUSTAINABLE DEVELOPMENT IN CHINA
Creator: Wang, Xiaoxiao
Date: 2012-07-11, 2012-07
Description: Compared to the rich literature on urban sprawl in Western cities, relatively little is known of the driving factors, processes, and future...
Show moreCompared to the rich literature on urban sprawl in Western cities, relatively little is known of the driving factors, processes, and future trends of urban sprawl in China. This research will analyze the socio-economic forces behind two parts of urban sprawl in China: urban decentralization (the creation of development zones and new towns) and urban renewal (infrastructural changes to existing urban fabrics) and reveal two basic characteristic for Chinese urban sprawl: a). de-densification; and b). expansion of urbanized areas (urban built-up areas). This proposal aims to use the term “urban sprawl” to consider the reasons behind urban land-use changes and urban pattern transformations on a regional level. It begins with definitions of sprawl in Western and Eastern countries, and follows an analysis of the social, political, and cultural factors of sprawl. Three case studies will focus on three urban centers in China: Beijing, Shanghai, and Guangzhou. Still another component is data analysis with the program SPSS based on related Index for urban sprawl and sustainable development for 15 top urban regions in China during 10 years. This research has explored causes of urban sprawl in China: a). the changing residential preferences of some residents: willing to move out of the core; and b). overcrowded, deteriorated, and old-fashioned structures in central cities becoming targets for demolition in pursuing a new era of modernity, prosperity, and renaissance. Then, this research has pointed out: a). uneven land reform is the key to understand Chinese-style urban sprawl and it is also the necessary condition to the paradox posed by development zones and urbanized villages; b). China’s urban sprawl is driven by both market and government forces; and c). there are a series of new conditions for urban sprawl in China, for example: rising private automobile ownership, rising demand for space and changing residential preference, local public policy, and the real-estate industry. This research intends to provide a comprehensive definition of “urban sprawl” in China, identify the patterns of urban sprawl and growth in three urban regions (Beijing, Shanghai, and Guangzhou), and illustrate the concepts and possible alternative strategies for green urban growth and change in China. Finally, it will offer suggestions on how to effectively control urban sprawl in China, as well as provide a pathway to achieving sustainable development.
Ph.D. in Architecture, July 2012
Show less

Title: MECHANICAL PROPERTIES AND SINTERING MECHANISMS OF POWDER METALLURGY TI6AL4V
Creator: Xu, Xiaoyan
Date: 2013, 2013-05
Description: Titanium has been identified as one of the key materials with a high strength to weight ratio that can reduce the weight of components and...
Show moreTitanium has been identified as one of the key materials with a high strength to weight ratio that can reduce the weight of components and thereby reduce energy consumption. Single press and sinter as a powder metallurgy technique has the potential to provide cost effective components. Armstrong prealloyed Ti6Al4V, HDH prealloyed Ti6Al4V, HDH blended Ti6Al4V powder and their mixtures were pressed and sintered at different conditions. The chemistry, mechanical and microstructural properties have been investigated to establish optimum processing parameters. Sintered parts were sent to Oshkosh Truck to test and compared with aluminum and steel parts. The Titanium and Ti6Al4V parts were successfully applied and tested. All the specimens passed the load test without failures. The sintering mechanisms of Armstrong prealloyed Ti6Al4V powder were investigated. At relative sintered densities of 75% to 90% (around 900°C), surface diffusion cooperate with grain boundary diffusion, which leads to densification of the powder compact. Around 900°C, grain boundary diffusion controls the sintering process. At 1000°C, boundary diffusion made little contribution to the densification of the Ti6Al4V powder compact. Above 900°C and below 91% sintered density, boundary diffusion controls sintering. Lattice diffusion dominates the densification process at higher temperatures (1100°C~1300°C). The sintering of master alloy blended Ti6Al4V powder has been investigated in order to elucidate the mechanism of sintering. Both blended powder compacts and diffusion couples were investigated using backscattered imaging and energy xvi dispersive analysis to determine the phases present and diffusion path on sintering at 1000ºC and 1100ºC. It is shown that transient liquid phase sintering does not occur and the reason for the rapid sintering of this material is due to enhanced diffusion kinetics resulting from a combination of the concentration gradient and stress induced by a phase transformation in the ternary system.
PH.D in Materials Science and Engineering, May 2013
Show less

Title: SUSTAINABLE, CONTROLLED, REACTION SYNTHESIS OF METALLIC WIRES AND STRIPS
Creator: Chen, Xin
Date: 2014, 2014-05
Description: The main purpose of this work is to investigate bi and tri-metallic metal com- binations as initiators which require an ability to have a self...
Show moreThe main purpose of this work is to investigate bi and tri-metallic metal com- binations as initiators which require an ability to have a self-sustaining exothermic reaction. Through the reaction, the initiator should achieve a temperature in excess of 500 C when in contact with a thermally conducting surface. Also the initiator must be in the form of a exible wire or strip of the order of one millimeter radius. There are four phases in my MS research project. First was identifying the potential candidate compounds for exothermic reaction. During this phase, I wrote a program using Mathematicar (Appendix A) to calculate the adiabatic temperature resulting from the reaction of di erent binary or ternary elemental combinations. The calculation took into account the speci c heats and any enthalpies of transformation occurring between room temperature and the adiabatic temperature. Based on the results of this program several suitable compositions were selected from three hun- dred candidates. The second phase was determining a methodology to manufacture selfCpropagating thin strips or wires. We attempted several methods including plate rolling, wire twisting, mechanical coating, chemical coating, and powder metallurgy. We successfully obtained self-propagating thin metal strips and wires using powder metallurgy methods. In the third phase, a transparent reaction box was constructed in order to provide a protective atmosphere (Ar gas) and connect to a data acqui- sition system to obtain the reaction temperature, initiation temperature and video materials of reactions. In the last phase, the reacted samples were characterized using Scanning Electron Microscope (SEM), Backscattered Electron detector (BSE), X-ray Di raction (XRD), Di erential scanning calorimeter (DSC), etc.
M.S. in Mechanical, Materials, and Aerospace Engineering, May 2014
Show less

Title: ISOLATION OF TRANSPOSON MEDIATED TRANSGLUTAMINASE MUTANTS OF DROSOPHILA MELANOGASTER
Creator: Yang, Hua
Date: 2016, 2016-05
Description: Transglutaminase, Tg, catalyzes the formation of isopeptide bonds crosslinking and stabilizing protein complexes. The best-known factor XIII...
Show moreTransglutaminase, Tg, catalyzes the formation of isopeptide bonds crosslinking and stabilizing protein complexes. The best-known factor XIII crosslinks fibrin in clots. Paradoxically, there is an unexpected and counterintuitive correlation between factor XIII levels and heart attack mortality. Since factor XIII strengthens fibrin and resists fibrinolysis, higher XIII activity would be expected to lead to more stable fibrin clots and so more fatal atherosclerotic plaques; but it actually results in reduced mortality. One hypothesis to explain this is that Tg activity may also stabilize cardiac muscle tissue. Studies have shown that Tg is expressed in human embryonic myoblasts. Therefore, we suggest that muscular attachments may be strengthened by Tg, and play a vital unrecognized role in the muscular attachment. Humans have 9 Tg genes, complicating studies. However Drosophila melanogaster, D.m., has only one Tg gene, and is an attractive model system. We isolated 39 mutant D.m. lines gene produced by transposon mobilization in locus in a "dirty" fashion expected to create random deletions within the Tg locus. We then characterized them by PCR and sequencing, as well as functional assays, in an attempt to develop a Tg null line to test this hypothesis. The aim is to identify a line with all of Tg removed, but with neighboring genes unperturbed. Once the approximate break points were identified by PCR, we did DNA sequencing to fully characterize the genomic breakpoint. According to the DNA sequencing results, one line is specific for Tg exon1, and eliminates one of the two known Tg transcripts. Another line eliminated almost the entire catalytic domain. We also did RT-qPCR for two lines that were sequenced to determine their genomic characteristics. Both of these lines are viable but with subtle developmental defects, showing that Tg deficiency is not lethal in D.m.
M.S. in Biology, May 2016
Show less

Title: MONITORING, MODELING, AND TREATMENT OF ODORS/ODORANTS AT WATER RECLAMATION PLANTS
Creator: Zhang, Yanming
Date: 2012-04-23, 2012-05
Description: A thorough study including odor monitoring, modeling and treatment as three important aspects of odor control in WRPs has been performed in...
Show moreA thorough study including odor monitoring, modeling and treatment as three important aspects of odor control in WRPs has been performed in this research. Measurement of H2S emissions from odor sources was proven to be an essential step in odor monitoring program. The H2S emission rates were measured from various sources throughout a WRP for 9 sampling events during winter and summer. During summer, both the average and the maximum emission rates of H2S from liquid treatment processes increased significantly compared to those measured during winter. However, for solids-handling processes, the emission rates remained constant because sludge characteristics did not vary throughout the year. The total sulfide concentrations present in liquid treatment processes were higher than those in preliminary and primary treatment units but at much lower levels in secondary treatment. Rates of H2S emission from the headworks were correlated to daily average wastewater temperature, TKN concentration, and flow rate. AERMOD was used as the modeling tool to evaluate the odor impact of Egan WRP on the surrounding communities. The emission rates could significantly affect the modeling results. Long-term H2S monitoring increases the possibility of developing the proper emission rate for the worst-case scenario. Excluding the modeling during the night would avoid overestimation of odor impact and excessive odor control. In the laboratory-scale study of O3 oxidation of H2S, O3 oxidation was proven to be a fast and effective method to remove H2S from the odorous air emitted from wastewater treatment processes. The increased initial ratio of O3/H2S enhances the removal rate of H2S. The consumption ratio of O3/H2S is a function of input reactant ratios. A multiple linear regression model (R2=0.84) has been developed to predict the H2S residual for given initial H2S and O3 concentrations and reaction time. The increased moisture content of the odorous air enhanced the H2S removal while DMS and DMDS inhibit H2S removal by competing for the limited O3 supply.
Ph.D. in Environmental Engineering, May 2012
Show less

Title: THERMODYNAMIC PROPERTIES AND PHASE EQUILIBRIA OF SELECTED HEUSLER COMPOUNDS
Creator: Yin, Ming
Date: 2015, 2015-12
Description: Heusler compounds are ternary intermetallics with many promising properties such as spin polarization and magnetic shape memory effect. A...
Show moreHeusler compounds are ternary intermetallics with many promising properties such as spin polarization and magnetic shape memory effect. A better understanding of their thermodynamic properties facilitates future design and development. Therefore, standard enthalpies of formation and heat capacities from room temperature to 1500 K of selected Heusler compounds X2YZ (X = Co, Fe, Ni, Pd, Rh, Ru; Y = Co, Cu, Fe, Hf, Mn, Ni, Ti, V, Zr; Z = Al, Ga, In, Si, Ge, Sn) and half-Heusler compounds XYSn (X = Au, Co, Fe, Ir, Ni, Pd, Pt, Rh; Y = Hf, Mn, Ti, Zr) were measured using high temperature direct reaction calorimetry. The measured standard enthalpies of formation were compared with those predicted from ab initio calculations and the extended semiempirical Miedema's model. Trends in standard enthalpy of formation with respect to the periodic classification of elements were discussed. The effect of a fourth element (Co, Cu, Fe, Pd; Ti, V; Al, Ga, In, Si, Ge) on the standard enthalpy of formation of Ni2MnSn was also investigated. Lattice parameters of the compounds with an L21 structure were determined using X-ray powder diffraction analysis. Differential scanning calorimetry was used to determine melting points and phase transformation temperatures. Phase relationships were investigated using scanning electron microscopy with an energy dispersive spectrometer. The isothermal section of the Fe-Sn-Ti ternary system at 873 K was established using equilibrated alloys. Three ternary compounds including the Heusler compound Fe2SnTi were observed. A new ternary compound Fe5Sn9Ti6 was reported and the crystal structure of FeSnTi2 was determined for the first time.
Ph.D. in Mechanical, Materials and Aerospace Engineering
Show less

Title: INVESTIGATION OF ANION EXCHANGE MEMBRANES FOR ELECTROCHEMICAL ENERGY CONVERSION AND STORAGE SYSTEMS
Creator: Wang, Lihui
Date: 2017, 2017-05
Description: The alkaline stability of poly (arylene ether) backbones in anion exchange membranes (AEMs) derivatized with quaternary benzyl N, N-...
Show moreThe alkaline stability of poly (arylene ether) backbones in anion exchange membranes (AEMs) derivatized with quaternary benzyl N, N- dimethylhexylammmonium (DMH+) and trimethylammonium (TMA+) cation groups were investigated in poly (2,6- dimethyl 1,4-phenylene) oxide (PPO) and Udel® polysulfone (PSF) polymers. Previous studies have demonstrated that quaternary ammonium and phosphonium groups trigger backbone degradation in commercially available poly (arylene ether)-based AEMs, despite the base polymers’ resilience to alkaline solutions. Herein, I demonstrate that the electron withdrawing or donating character in the poly (arylene ether) backbone ultimately dictates whether the prepared AEMs will become brittle in alkaline media due to cation-triggered backbone degradation (Arges, Parrondo, Johnson, Nadhan, & Ramani, 2012a; Christopher G. Arges, Lihui Wang, Javier Parrondo, & Vijay Ramani, 2013). Mitigation of cation-triggered backbone degradation was only achieved when electron withdrawing substituents (not including the cation), such as sulfone or bromine, were eliminated from the polymer backbone (or, alternately, when electron donating groups were present). Hence, PPO AEMs prepared through chloromethylation, rather than free radical bromination, were resistant to backbone hydrolysis in alkaline media because each cation-functionalized repeat unit had two electron-donating methyl groups rather than a single methyl group. This study presents some design rules for preparing mechanically stable poly (arylene ether) AEMs from low cost, commercially available polymers for alkaline electrochemical devices.
Ph.D. in Chemical Engineering, May 2017
Show less

Title: EFFECT OF REACTANT CONCENTRATIONS AND AGING EFFECT IN THE SYNTHESIS OF SILVER NANORODS
Creator: Wang, Guan
Date: 2016, 2016-05
Description: In the recent years, anisotropic metallic nanoparticles have drawn much attention because of their unique optical properties. Particularly,...
Show moreIn the recent years, anisotropic metallic nanoparticles have drawn much attention because of their unique optical properties. Particularly, gold and silver nanorods show great potential in extensive applications such as health care, food storage, drug delivery, biosensor, and cancer treatment. Among a variety of nanorods synthesis methods, the seed-mediated growth approach stands out due to its mild and convenient experimental conditions. However, there exist two defects of this method, the poor reproducibility and low yield of nanorods. In order to create nanoparticle systems of reproducible quality in high yields, a deeper understanding of the mechanism of nanorods formation as well as identifying the more important variables is necessary. In this study, the original seed-mediated growth method has been modified to promote the reproducibility and yield of nanorods. Effects of CTAB concentration and ages of growth solution have been investigated in the nanorods formation process. The results suggest that a high concentration of CTAB is not necessary for the growth process and the age of growth solution can affect the optical performance of nanorods. In a brief survey on the stability property of nanorods, it shows that the degradation rate decreases with increasing concentrations of CTAB.
M.S. in Chemical Engineering, May 2016
Show less

Title: EFFECT OF TEMPERATURE, MOISTURE CONTENT AND SOIL SURFACE AREA ON THE BIOLOGICAL DEGRADATION OF BIOSOLIDS ADDED TO SOIL
Creator: Wen, Dongqi
Date: 2016, 2016-05
Description: The objective is to develop and apply an organic matter degradation model (OMDM) that predicts changes in the biological degradation of...
Show moreThe objective is to develop and apply an organic matter degradation model (OMDM) that predicts changes in the biological degradation of organic matter added to soils as a function of soil temperature, moisture content and mineral surface area using data from field and laboratory measurements. A one year long laboratory study was conducted to determine biosolids microbial degradation rates (21 ˚C and 20% moisture content) for soils from eight different fields Biosolids microbial degradation rates were also determined for the eight soils under field condition (10 ˚C and 10% moisture content) by applying a degradation rate model (DRM). The total mineral surface areas for 27 soil samples were also determined. Regression analysis revealed that the degradation rate was positively associated with mineral soil surface area (R2=0.85) and that the biosolids application rate is not significantly associated with the biosolids degradation rate (p value =0.35>0.01). The OMDM determines a decomposition rate of 1.04 yr-1 at 30 ˚C, 20% moisture content, and 10 m2/g soil and provides correction factors for changes in soil temperature, moisture, and mineral surface area. The model predicted in changes of the biological degradation rate of biosolids added to soils with mineral surface areas that vary from 1 to 10 m2/g soil under laboratory and field conditions. A comparison of the measured and simulated degradation rates for eight different soils produced R2 = 0.87 for field data. The model was also able to predict the degradation rate of biosolids for 19 additional soils under field conditions (R2=0.89). The model was also applied to agricultural plant litter. The estimated degradation rates are 0.45 yr-1 corn stover, 0.35 yr-1 oats, 0.26 yr-1 wheat, and 0.13 yr-1 millet at 30 ˚C, 20% moisture content and 10 m2/g. This study demonstrates that the effects of environmental conditions and soil mineral surface area have a significant impact on degradation rates of organic matter and must be considered when assessing degradation rates for organic matter added to soil. Higher temperatures and moisture content and finer soils are related to larger degradation rates.
Ph.D. in Environmental Engineering, May 2016
Show less

Title: RE-IMAGING ANTIQUITIES IN LINCOLN PARK: DIGITIZED PUBLIC MUSEOLOGICAL INTERACTIONS IN A POST-COLONIAL WORLD
Creator: Whittaker, Daniel Joseph
Date: 2015, 2015-12
Description: The study of an architecture of autonomy consists of theoretical investigations into the realm of building types where a sole use or purpose...
Show moreThe study of an architecture of autonomy consists of theoretical investigations into the realm of building types where a sole use or purpose is manifest in a structure that could, site provided, be constructed. However, provisions that conventional architecture traditionally provide are not present in these explorations. Technological advancements such as indoor plumbing, electric lights, and vertical conveyance systems in the form of elevators and escalators are excluded. Platonic geometric form-making are instead thoroughly investigated, imagined, and manipulated for the purposes of creating new spatial experiences. The desired resultant is an architecture of singularity, an architecture of fantastical projection. Through a series of two theoretical ritual-based investigations, three-dimensional form manipulation and construction of proportioned scale models, the essence of elements that compose a spatial experience contributed to a collection of metaphorical tools by which the designer may use to build a third imagined reality: the re-imagination of the archetypal museum. A building whose purpose is not solely to house ancient objects in a near hermetically-sealed environment, free of temperature, humidity and ultra-violet light aberrations, but is a re-imagined. A structure meant to engage the presence of two seemingly divergent communities: the local patron/visitor and the extreme distant denizen. This paper also examines key contemporary global artists’ work and their contributions to the fragmentation / demolition of architectural assemblages for thepurposes of re-evaluating the familiar vernacular urban landscape while criticallypositioning the rôle of both the artifact and gallery in shaping contemporary audience’s museum experiences. The power of the internet and live-camera broadcasting of images utilizing both digital image recording and full-scale screen-projections enable the exploration of “transporter-type” virtual-reality experiences: the ability to inhabit an art work’s presumed original in situ location, while remaining in Chicago as a visitor within a vernacular multi-tenant masonry structure: vacated, evicted, and deconstructed for the purposes of displaying art amidst a new urbane ruin. The complexities of this layered experience is meant to simultaneously displace and interrupt a typical set of so-called a priori gallery expectations while providing the expectant simulacrum that video cameras and screens provide, whetting a contemporary patron’s appetite.positioning the rôle of both the artifact and gallery in shaping contemporary audience’s museum experiences. The power of the internet and live-camera broadcasting of images utilizing both digital image recording and full-scale screen-projections enable the exploration of “transporter-type” virtual-reality experiences: the ability to inhabit an art work’s presumed original in situ location, while remaining in Chicago as a visitor within a vernacular multi-tenant masonry structure: vacated, evicted, and deconstructed for the purposes of displaying art amidst a new urbane ruin. The complexities of this layered experience is meant to simultaneously displace and interrupt a typical set of so-called a priori gallery expectations while providing the expectant simulacrum that video cameras and screens provide, whetting a contemporary patron’s appetite.positioning the rôle of both the artifact and gallery in shaping contemporary audience’s museum experiences. The power of the internet and live-camera broadcasting of images utilizing both digital image recording and full-scale screen-projections enable the exploration of “transporter-type” virtual-reality experiences: the ability to inhabit an art work’s presumed original in situ location, while remaining in Chicago as a visitor within a vernacular multi-tenant masonry structure: vacated, evicted, and deconstructed for the purposes of displaying art amidst a new urbane ruin. The complexities of this layered experience is meant to simultaneously displace and interrupt a typical set of so-called a priori gallery expectations while providing the expectant simulacrum that video cameras and screens provide, whetting a contemporary patron’s appetite.positioning the rôle of both the artifact and gallery in shaping contemporary audience’s museum experiences. The power of the internet and live-camera broadcasting of images utilizing both digital image recording and full-scale screen-projections enable the exploration of “transporter-type” virtual-reality experiences: the ability to inhabit an art work’s presumed original in situ location, while remaining in Chicago as a visitor within a vernacular multi-tenant masonry structure: vacated, evicted, and deconstructed for the purposes of displaying art amidst a new urbane ruin. The complexities of this layered experience is meant to simultaneously displace and interrupt a typical set of so-called a priori gallery expectations while providing the expectant simulacrum that video cameras and screens provide, whetting a contemporary patron’s appetite.positioning the rôle of both the artifact and gallery in shaping contemporary audience’s museum experiences. The power of the internet and live-camera broadcasting of images utilizing both digital image recording and full-scale screen-projections enable the exploration of “transporter-type” virtual-reality experiences: the ability to inhabit an art work’s presumed original in situ location, while remaining in Chicago as a visitor within a vernacular multi-tenant masonry structure: vacated, evicted, and deconstructed for the purposes of displaying art amidst a new urbane ruin. The complexities of this layered experience is meant to simultaneously displace and interrupt a typical set of so-called a priori gallery expectations while providing the expectant simulacrum that video cameras and screens provide, whetting a contemporary patron’s appetite.
M.S. in Architecture, December 2015
Show less

Title: HOUSING CHINESE DREAMS
Creator: Wong, Jing Jie
Date: 2017, 2017-07
Description: The Chinese Dream is President Xi Jinping's integrative and transformative vision for China, with the goals to achieve "a great rejuvenation...
Show moreThe Chinese Dream is President Xi Jinping's integrative and transformative vision for China, with the goals to achieve "a great rejuvenation of the Chinese nation". However, the realities in China seem to be far from the conditions of a dream. The emerging Chinese middle class are eager to join the army of slaves to their impossible mortgages for their bedroom town homes, in fulfillment of what the modern Chinese psychodynamics have collectively decided to be a necessity in pursuance of a good life. So, where are the capacities of the Chinese Dream for the individuals in this modern times? The dream has to address the deteriorating sense of belonging and home of the millions of working middle class, before it can even consider itself a collective effort. The individuals should be encouraged to dream and strive, in order for this to happen, the fundamentals of a good living environment must be collectively accessible. Studies on the collective forms of housing in China's recent history had shed light onto the importance of urban elements such as the hutong network and socialist work unit in social control. However, a case study on China's gated housing models had also opened up discussions on what a complete razing of culture, history and forced resettlements had done in the name of providing quantities of housing within China's neoliberal shift. This thesis explores the elements of providing quality living environments for this group of people that have been called upward-mobile, tech-savvy and entrepreneurial. With the idea of owning a house becoming increasingly important to the Chinese middle class, architecture attempts to bridge gaps between the realities of the sub-par housing towers in gated peripheral areas and the dying traditions of collectivism. By looking at the success of the hutong and danwei dormitories as spaces for social order as well as spaces for commercial and social interaction, a translation of this is deemed to be emulated in modern housing. A super-hybrid of dwellings and designed "programmatic infection" is bound to happen by studying the development of "dream-like" housing prototypes in history.
M.S. in Architecture, July 2017
Show less

Title: Parking Demand Forecasting Using Asymmetric Discrete Choice Models with Applications
Creator: Zhang, Ji
Date: 2023
Description: Using discrete choice models to forecast travelers parking location choice has been a branch of parking demand research for many years. The...
Show moreUsing discrete choice models to forecast travelers parking location choice has been a branch of parking demand research for many years. The most used discrete choice models have fairly simple mathematical expressions, such as the probit and logit models. The application of simple models helps release the computational burdens brought by parameter estimation tasks in practice, but the cost is the unwanted properties of classic models such as the “symmetry property” that we argue is often undesirable in many fields. To some extent, the symmetry property of related models limits the shape of curves that makes the model fitting less flexible technically. This study addresses the following question: “Can discrete choice models with asymmetry property outperform classic models with symmetry property in forecasting travelers’ parking location choices?” The contributions of this study include: (1) providing a new perspective of using asymmetric discrete choice models to explain and forecast individual’s parking location choice; and (2) completing the travel demand forecasting process from choices of the destination zone centroid to the parking location, enabling parking choice forecasting. This provides a generalized framework to calibrate and validate asymmetric discrete choice models with the field observed parking facility-specific arrival profile data integrated into a large-scale, high-fidelity regional travel demand model. Further, an experimental study is conducted to compare the performance of the proposed asymmetric discrete choice models in the parking demand forecasting framework. The results suggest that asymmetric discrete choice models for individual’s parking choice modeling outperform the symmetric discrete choice models such as the logit models owing largely to their flexibility of parameter fitting and training using the available dataset.
Show less

Title: Estimation of Platinum Oxide Degradation in Proton Exchange Membrane Fuel Cells
Creator: Ahmed, Niyaz Afnan
Date: 2024
Description: The performance and durability of Proton Exchange Membrane Fuel Cells (PEMFCs) can be significantly hampered due to the degradation of the...
Show moreThe performance and durability of Proton Exchange Membrane Fuel Cells (PEMFCs) can be significantly hampered due to the degradation of the platinum catalyst. The production of platinum oxide is a major cause of the degradation of the fuel cell system, negatively affecting its performance and durability. In order to predict and prevent this degradation, this research examines a novel method to estimate degradation due to platinum oxide formation and predict the level of platinum oxide coverage over time. Mechanisms of platinum oxide formation are outlined and two methods are compared for platinum oxide estimation. Linear regression and two Artificial Neural Network (ANN) models, including a Recurrent Neural Network (RNN) and Feed-forward Back Propagation Neural Network (FFBPNN), are compared for estimation. The estimation model takes into account the influence of cell temperature and relative humidity.Evaluation of relative errors (RE) and root mean square error (RMSE) illustrates the superior performance of RNN in contrast to GT-Suite and FFBPNN. However, both RNN and GT-Suite showcase an average error rate below 5% while the FFBPNN had a higher error rate of approximately 7%. The RMSE of RNN shows mostly less compared to FFBPNN and GT-Suite, however, at 50% training data, GT-Suite shows lowest RMSE. These findings indicate that GT-Suite can be a valuable tool for estimating platinum oxide in fuel cells with a relatively low RE, but the RNN model may be more suitable for real-time estimation of platinum oxide degradation in PEM fuel cells, due to its accurate predictions and shorter computational time. This comprehensive approach provides crucial insights for optimizing fuel cell efficiency and implementing effective maintenance strategies.
Show less

Title: Parking Demand Forecasting Using Asymmetric Discrete Choice Models with Applications
Creator: Zhang, Ji
Date: 2023
Description: Using discrete choice models to forecast travelers parking location choice has been a branch of parking demand research for many years. The...
Show moreUsing discrete choice models to forecast travelers parking location choice has been a branch of parking demand research for many years. The most used discrete choice models have fairly simple mathematical expressions, such as the probit and logit models. The application of simple models helps release the computational burdens brought by parameter estimation tasks in practice, but the cost is the unwanted properties of classic models such as the “symmetry property” that we argue is often undesirable in many fields. To some extent, the symmetry property of related models limits the shape of curves that makes the model fitting less flexible technically. This study addresses the following question: “Can discrete choice models with asymmetry property outperform classic models with symmetry property in forecasting travelers’ parking location choices?” The contributions of this study include: (1) providing a new perspective of using asymmetric discrete choice models to explain and forecast individual’s parking location choice; and (2) completing the travel demand forecasting process from choices of the destination zone centroid to the parking location, enabling parking choice forecasting. This provides a generalized framework to calibrate and validate asymmetric discrete choice models with the field observed parking facility-specific arrival profile data integrated into a large-scale, high-fidelity regional travel demand model. Further, an experimental study is conducted to compare the performance of the proposed asymmetric discrete choice models in the parking demand forecasting framework. The results suggest that asymmetric discrete choice models for individual’s parking choice modeling outperform the symmetric discrete choice models such as the logit models owing largely to their flexibility of parameter fitting and training using the available dataset.
Show less

Title: Estimation of kinetic parameters of the Coronavirus main protease by Bayesian regression and utility for drug design
Creator: La, Van Ngoc Thuy
Date: 2024
Description: The main protease (MPro) plays a crucial role in the Coronavirus life cycle and is a target for newly developed antivirals against SARS-CoV-2....
Show moreThe main protease (MPro) plays a crucial role in the Coronavirus life cycle and is a target for newly developed antivirals against SARS-CoV-2. MPro is conserved across various members of the coronavirus family. The enzyme of SARS-CoV-2 and other members of the coronavirus family share similar structures and functions, commonly existing as obligate dimers. However, MPro from MERS-CoV exhibits weaker dimerization and often exists as a monomer under biochemical assay conditions, which may not accurately reflect the conditions relevant to antiviral therapy in infected cells.Interestingly, because ligand binding increases dimerization, the addition of ligands has been reported to enhance MPro activity at low concentrations before reducing it at higher concentrations. This phenomenon, known as ligand-induced dimerization, was observed not only in biochemical assays of MERS-CoV MPro but also of SARS-CoV-2 mutated MPro with weakened dimerization. Unfortunately, there are currently no published biochemical models that quantitatively fit these non-monotonic concentration-response curves. This poses a significant challenge in estimating IC50 from these curves, which is an important metric for drug potency and commonly used in drug screening. As a result, predicting compound behavior in cellular models becomes challenging.To address this challenge, we developed an enzyme kinetic model that integrates dimerization and ligand binding. We utilized Bayesian regression for the model to fit datasets published in the aforementioned study of SARS-CoV-2 MPro. Subsequently, we adjusted the model to achieve a global fit for multiple datasets of MERS-CoV MPro and estimate IC50 values. Finally, we examined the correlation between estimated IC50 and cellular EC50, demonstrating that our model is capable of predicting cellular EC50 for the biphasic curves observed in MERS-CoV MPro.
Show less

Title: Selective Interface Reaction Studies during Atomic Layer Deposition Process Based on Surface Properties of Metal Oxide Substrate and Chemical Properties of Precursors
Creator: Luo, Chunxin
Date: 2024
Description: Site-selective atomic layer deposition (SS-ALD) on metal oxide nanoparticles will require subtle surface chemical control through site...
Show moreSite-selective atomic layer deposition (SS-ALD) on metal oxide nanoparticles will require subtle surface chemical control through site-specific surface functionalization (e.g. selective hydration) or highly discriminating reactivity. Two main factors, including the properties of substrate and proton-affinity of the precursors, which would affect the selectivity of ALD process will be discussed and the mechanism will be revealed in this thesis.The adsorption step on substrate surface of the metal precursors will affect the first half reaction of ALD process. Our hypothesis here is that surface hydroxyl group on different oriented metal oxide surface have different desorption temperature points. In this case, we can control the adsorption step by simply adjusting substrate temperature to targeting temperature point where it allows us to achieve selectively removal of the targeting hydroxyl groups while leaving the hydroxyl remain on desired site. Selectively dihydroxylation on In2O3 (111) and (211) single crystal surface is studied, and further SS-ALD is achieved on high-oriented In2O3 (111) thin-film by simply thermal treatment, which indicated that discriminant dihydroxylation can be a promising pathway to SS-ALD. Thermal dehydration of facet-specific anatase TiO2 truncated-octahedron, disks, and rods samples is investigated by Fourier-transform infrared spectroscopy (FTIR). Potential facet-specific reaction window was revealed. However, the various oxidation state on transition metal created more complicated surface atomic arrangement, which make the study of thermal dihydroxylation on nanoparticles even more complicated. Thus, we turn our focus back on the In2O3 material. Well-constructed and facet specific In2O3 nanoparticle cube, octahedron and trapezohedron with only one of (100), (111), and (211) surface exposed, respectively, were synthesized and investigated by DRIFT. Further ALD treated In2O3 nanoparticles were studied. Moreover, epitaxial growth of In2O3 on YSZ (100) and (111) substrates were obtained by thermal ALD method. Post-annealing treatments applied on these epitaxial growth In2O3 samples. The relationship between the grow orientation of single crystal surface and electrical performance are investigated and discussed. Finally, some preliminary studies of the relationship between the ligand-dependent precursor and ALD performance were conducted by using the in-situ FTIR method. Surface reaction mechanisms during the ALD process with porous AAOAl film as substrate were studied. Selectivity exhibited from DMAI precursor was investigated and discussed. ALD performance and related surface reaction of Ga precursor such as Ga2(NMe2)6, Ga(amd)(NMe2)2, and Ga(amd)3 were studied by in-situ FTIR as well. Overall, thermal evolution of surface hydroxyl group on faceted TiO2, In2O3 nanoparticles were probed by temperature variable FTIR. Selective proton-dependent chemical reaction can be achieved on different oriented metal oxide surface. Orientation dependent electrical properties was studied on high-oriented In2O3 (111) and In2O3 (100) surface. An alternative way of in-situ FTIR measurement to study the surface reaction during ALD process was designed and investigated. Despite the remaining work, the concept and methodology of site-selective atomic layer deposition (SS-ALD) and associated probing techniques have the potential to captivate researchers in the fields of surface chemistry, semiconductors, and electrical devices.
Show less

repository.iit

Search the repository

Pages

Pages