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Title: RAPID ESTIMATION OF INDUCTION MACHINE STATOR CORE LOSSES
Creator: Narayana Pillai, Sreekanth
Date: 2015, 2015-05
Description: This thesis presents a technique for the rapid estimation of induction machine stator core losses using a series of magneto-static finite...
Show moreThis thesis presents a technique for the rapid estimation of induction machine stator core losses using a series of magneto-static finite element analyzes. The methodology is based on partially uniting two previously developed techniques. The first technique allows for the rapid estimation of steady state three phase induction machine properties under field oriented conditions using an iterative magneto-static finite element analysis approach where sinusoidally distributed currents are imposed on the rotor. The second technique utilized was originally developed to characterize the steady state time domain behavior of a three phase synchronous machine using a series of magneto-static finite element simulations with the rotor through one phase belt. In the induction machine analysis application, the rotor is rotated through one phase belt with sinusoidally distributed rotor currents imposed and adjusted to maintain field oriented condition at each rotor position. Stator flux densities are sampled at each rotor position. Exploiting the magnet symmetries, the radial and tangential flux density waveforms in the stator tooth tip, stator tooth, stator tooth yoke and stator yoke regions are reconstructed for one electrical cycle using a minimum number of rotor positions per simulation steps. From the reconstructed stator flux density waveforms, the stator core losses can be estimated using a number of loss models. In this thesis what is known as the CAL2 method is utilized to estimate the loss in each stator region. The rapid estimation of induction machine stator core losses was implemented in MATLAB to script the behavior of FEMM, an open source finite element analysis program. To enable the technique to be used for a wide range of induction machine geometries and make possible future population based design optimization, a flexible parametric geometry was created. To verify the accuracy of the proposed rapid estimation technique, a comparison was carried out on a 2 HP, 3-phase, 4 pole, 60 Hz induction machine with 36 stator slots and 28 rotor slots, between the proposed technique and a transient element analysis carried out in JMAG, a commercial finite element package, for aveerage torque, stator flux densities and total stator core losses.
M.S. in Electrical Engineering, May 2015
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Title: DEVELOPMENT OF SITE-SPECIFIC SEISMIC HAZARD MODEL FOR THE STABILITY ANALYSIS OF AN EMBANKMENT DAM
Creator: Simanjuntak, Nico Aditya
Date: 2017, 2017-05
Description: Time-history dynamic analysis requires proper selections of earthquake records based on the design earthquake and site-specific...
Show moreTime-history dynamic analysis requires proper selections of earthquake records based on the design earthquake and site-specific characteristics. The selected earthquake records, most of the time, must be scaled to match the design response spectrum. The design response spectrum was a derivation of a seismic hazard model with consideration of site-specific effect. The hazard model was developed by combining the deterministic seismic hazard analysis (DSHA) and the probabilistic seismic hazard analysis (PSHA). Considering that the observed structure in this study is an embankment dam located at seismically active region, the deterministic hazard model was represented by the 84th percentile (median-plus-one standard deviation) spectra while the probabilistic hazard model provided a uniform hazard spectrum (UHS) with 1% probability of being exceeded in 100 years of structure’s lifetime. The combined hazard model shows the response at the bedrock, thus, the propagation to ground surface was also analyzed by assuming several scenarios of soil deposit. The study assumed four scenarios of site-specific classes A&B, C, D, and E, with three ground motion records were selected for each scenario were selected. Each ground motion was scaled to meet the design response spectrum of each scenario. Performance of the dam against each ground motion was analyzed to evaluate parameters such as stability by using factor of safety, and deformation at the crest to check the freeboard status after earthquake event. The results show that the model remains stable after experiencing seismic force on site class C or lower, while site class D yielded nearly fail condition (average FOS 1.06) and all motions in site class E have failed the dam.
M.S. in Civil Engineering, May 2017
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Title: ENVIRONMENTAL PERFORMANCE VS. FINANCIAL PERFORMANCE, MARKET INEFFICIENCY AND INVESTMENTS
Creator: He, Chaohua
Date: 2014, 2014-07
Description: It is challenging to de ne corporate environmental performance or corporate nancial performance. In this study, a company is considered to...
Show moreIt is challenging to de ne corporate environmental performance or corporate nancial performance. In this study, a company is considered to have good environmental performance (namely, be green, environment-friendly or environmentally responsible) if it is among the Top 100 of the 500 US greenest companies ranked by Newsweek, or has environmental strength(s) and no environmental concern in terms of the KLD ratings. A company is regarded to have good nancial performance if it has a high raw return, Sharpe ratio, and excess (or abnormal) return over various benchmarks. Preference will be given to excess return estimated using the Carhart four-factor model [14]. A previous published longitudinal study, co-authored with my advisor [13], unveils that: 1) environmentally responsible companies tend to experience signi cantly positive abnormal performance in the long horizon (e.g. from the fourth to seventh year after being selected); 2) the value-adding e ect and the market's upward price adjustments on undervalued intangible environmental strength(s) might have resulted in the long-term outperformance. Would environmentally responsible companies still outperform during shorter horizons, such as the event period of an environmental disclosure? Using event study methodologies, this paper investigates market responses to independent Newsweek environmental disclosures by analyzing cross-sectional and time-series abnormal security returns. Results suggest that the Top 100 greenest companies tend to display signi cant abnormal returns within 4 days after a disclosure, and the signi cant abnormal returns generally persist for no more than 3 trade days. e.g., the Carhart four-factor abnormal return, with statistical signi cance, is averaged at 0.50% per day over the four disclosure events. The ndings are robust to di erentmodels of normal return, removal of outliers, elimination of confounding e ects, controlling for characteristic factors, and adjusting for cross-sectional correlation and volatility shift on test statistics using BMP-adjusted technology[56]. Signi cant abnormal returns over the event period may indicate ine ciency of the nancial market. Fama-Macbeth regressions further reveal that short-horizon abnormal returns could be explained by a spectrum of characteristic variables, green investing, arbitrage trading, and/or various psychological biases. Complementing the cited longitudinal study, a portfolio-level comparison reveals that an actively managed green portfolio outperforms an actively managed nongreen portfolio in terms of raw return and risk-adjusted measures such as Sharpe ratio, Jensen's alpha and Fama-French alpha in the long horizon. The results are robust to di erent portfolio weighting technologies and the consideration of turnover costs. In addition, the green portfolio's outperformance is driven by a bunch of small, aggressive and relatively inactive stocks that have better performance than the market predicts. No evidence shows that the ever-increasing demand on green securities leads to the green portfolio's outperformance, because green stocks are actually less actively traded. Panel regressions further indicate that long-horizon corporate economic performance positively correlates to historical corporate environmental performance.
Ph.D. in Management Science, July 2014
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Title: STRUCTURAL SEISMIC PERFORMANCE EVALUATION WITH CONSIDERATION OF ECONOMIC VULNERABILITY
Creator: Romero, Daniela Zuloaga
Date: 2014, 2014-05
Description: Performance evaluation of structures has until now been based on evaluation of maximum displacements, interstory drifts, deformation patterns,...
Show morePerformance evaluation of structures has until now been based on evaluation of maximum displacements, interstory drifts, deformation patterns, ductility and other similar parameters; a relative economic loss estimation as a performance measure for the structure is the next step that follows, and is what has been investigated in this work. For this study a steel mid-rise structure was designed according to code provisions using modal spectral analysis, after which it was subjected to an Incremental Dynamic Analysis (IDA) procedure to evaluate the capacity curve of the building. The capacity analysis was then used to determine damage states and compute fragility curves. Finally, economic relative loss values were assigned to represent each designated damage state, for which the mean damage ratio was computed (in terms of economic loss relative to total replacement cost) as a function of spectral displacement.
M.S. in Civil Engineering, May 2014
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Title: SIZE AND VALUE RISK IN FINANCIAL FIRMS
Creator: Baek, Seungho
Date: 2013, 2013-12
Description: Although the Fama and French’s three factor model is now the most popular replacement for CAPM in corporate finance and investment management,...
Show moreAlthough the Fama and French’s three factor model is now the most popular replacement for CAPM in corporate finance and investment management, the exclusion of financial firms can be questioned on both theoretical and empirical grounds. Financial firms are around 19 percent of the value of the U.S. stock market. The financial service industry is the major industry in many large U.S. cities including New York, Chicago, Los Angeles and Miami in that their GDPs of financial services for each city are more than 23 percent. Also, there is no theoretical reason for excluding financial firms. Modigliani and Miller [31] [32] suggest that leverage affects beta, but it does not invalidate the capital asset pricing model. It would therefore be more satisfying if the pricing model applied generally, rather than being restricted to nonfinancial corporations. From this consideration, this paper assesses the validity of size and value risk as common risk factors to measure of expected equity returns in financial companies based on the fact that Fama and French [11] [12] excluded financial firms in their study of the cross-section of expected stock returns. The findings from empirical asset pricing tests suggest that size and value risk premia commonly exist in both nonfinancial and financial firms even if two factors are less explicable in financial firms, that an interest rate risk premium (ΔL/L) which defined as a financial firm specific risk factor only appears in financial companies.
PH.D in Management Science, December 2012
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Title: NON-NEWTONIAN EFFECTS IN HEMODYNAMIC SIMULATIONS OF THE CEPHALIC VEIN IN END STAGE RENAL DISEASE PATIENTS
Creator: Mahmoudzadeh Akherat, Seyed Mohammad Javid
Date: 2013, 2013-12
Description: The objective of this research is the determination of Hemodynamic Parame- ters (HDP) in End Stage Renal Disease (ESRD) patients which is done...
Show moreThe objective of this research is the determination of Hemodynamic Parame- ters (HDP) in End Stage Renal Disease (ESRD) patients which is done via implemen- tation of Computational Fluid Dynamics (CFD) in a two dimensional computational domain which provides a non-invasive and cost e ective means of studying the pa- tient population. The medical procedure needed for these patients is essential for the success of chronic hemodialysis. The most common medical procedure currently in this eld for creating vascular access (VA) are arteriovenous stulae (AVF). However, there are many access failures reported in these patients mainly due to Cephalic Arch Stenosis (CAS), which is related to the progression of intimal hyperplasia. Although various access techniques have been developed to address this issue, still hemodialysis access dysfunctions remains one of the main causes of mortality in the hemodialysis patient population. The expense of providing medical care to this patients population for the placement and maintenance of the vascular access was estimated to be 23.9 billion dollars in 2007 in the United States alone according to United States Renal Database System (USRDS). As stated above, it is our intention to observe a cohort of ESRD patients who received VA and simulate their blood ow through their cephalic vein with their spe- ci c HDP and characteristics. In order to perform these simulations, proper viscosity models have to be taken into consideration to increase the accuracy of the outcome of the numerical solution to Navier-Stokes equations. Many articles have been published to address the proper use of constitutive functions in simulation of blood ow. However, the choice of adequate viscosity function for CFD blood ow simulation in ESRD patients receiving AVF and a ma- nipulated vascular system in general has not received proper attention. Furthermore, it was discerned that the correct choice of viscosity function to capture the non- xii Newtonian behavior of blood is of utmost importance in this context since the ESRD patient population experience drastic alteration in blood viscosity throughout the hemodialysis treatment. Various viscosity functions have been tested for this pur- pose, namely, Quemada, Walburn-Schenck and Modi ed Cross. The results exhibit no major di erences in the velocity eld and general ow characteristics compared to a corresponding identical Newtonian blood ow simulation for Reynolds of 500. The results indicate that the choice of Newtonian viscosity to simulate the blood ow in ESRD patients with VA is acceptable. However, the Newtonian simulation of these ows may over predict the sites prone to stenosis and Intimal Hyperplasia (IH) since these simulations tend to exhibit lower Wall Shear Stress (WSS) values in the recircu- lation regions compared to non-Newtonian simulations. Sites of low WSS are thought to be contributory factors to IH. Hence, the use of proper non-Newtonian constitu- tive models is suggested in this context. The di erences between non-Newtonian and Newtonian assumptions are further ampli ed when unsteady cases with Reynolds of 1000 are concerned. Navier-Stokes solutions obtained from CFD simulations re- vealed that the discrepancies between the two assumptions are very appreciable for unsteady cases. In light of the results for unsteady cases, it was concluded that for non-physiological ows in curved vessels that are encountered in this study, the non-Newtonian assumptions is the correct choice. Further investigation is required to simulate the blood ow in a three di- mensional domain. In addition, a more thorough comprehension has to be obtained regarding the correlation of HDP with the onset and progression of CAS, particu- larly in unsteady hemodynamic ows. The etiology of stenosis in cephalic veins is of scienti c and clinical importance and needs to be separately investigated.
M.S. in Mechanical and Aerospace Engineering, December 2013
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Title: COMPUTATIONAL ACCESS FLOW REDUCTION EFFECT ON WALL SHEAR STRESS IN BRACHIOCEPHALIC FISTULAE
Creator: Wlodarczyk, Marta P.
Date: 2017, 2017-05
Description: The population of patients with end stage renal disease (ESRD) is growing at a rate higher than the global population. The only viable...
Show moreThe population of patients with end stage renal disease (ESRD) is growing at a rate higher than the global population. The only viable treatment for these patients is a kidney transplant. However, in the absence of a suitable kidney donor, renal patients are left with hemodialysis as a renal replacement therapy. Hemodialysis is facilitated through arteriovenous fistula (AVF), and the particular interest in this investigation is brachiocephalic fistula (BCF). The survival of dialysis patients depends on maintaining patency of fistula over a prolonged period of time. The extreme hemodynamic environment that is created by BCF triggers the onset of neointimal hyperplasia (NH) in most renal dialysis patients, which leads to access failure via stenosis. This is because the hemodynamics in AVF are well outside the normal physiological range. Computational fluid dynamics (CFD) along with shape optimization allows for the study of the hemodynamic parameters such as wall shear stress that have been shown to be detrimental in the future occurrence of cephalic arch stenosis. In this study, CFD modeling and identification of hemodynamic patterns was possible in three dimensions due to advanced post processing of IVUS patient-specific geometries. A method utilizing 3D CFD and shape optimization has been developed to implement Miller’s banding method used in clinical practice to evaluate its impact on WSS and onset of neointimal hyperplasia. The level of banding represented by a constriction is in fact a patient specific value and is not a trivial solution of minimum flow rate necessary to conduct hemodialysis; hence suggesting that even restoring the inlet velocity to the velocity pre-fistula creation might not reduce incidence of cephalic arch stenosis. The findings of this study support the previous hypothesis that non-homeostatic WSS distributions trigger neointimal hyperplasia and resulting venous stenosis. The important outcome is that the presented computational framework allows for evaluation of Miller's banding method for reducing the blood flow rate via surgical constriction and identification of a patient-specific banding level that restores the WSS to the normal physiological range.
M.S. in Mechanical and Aerospace Engineering, May 2017
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Title: NEOVASCULARIZAnON WITHIN POROUS PEG HYDROGELS
Creator: Chiu, Yu-chieh
Date: 2011-11, 2011-12
Description: Development of engineered tissues of clinically relevant size requires the ability to control vascularization within biomaterial scaffolds....
Show moreDevelopment of engineered tissues of clinically relevant size requires the ability to control vascularization within biomaterial scaffolds. Poly(ethylene glycol) (PEG) hydrogels have been extensively investigated for use as synthetic scaffolds to support engineered tissue formation. The goal of this work described was to develop techniques that can be used to enhance vascularized tissue formation in PEG-based hydrogels. In the first part of the study a technique was developed to generate porous PEG hydrogels using a salt leaching technique. This technique was then used to examine the role of pore size on vascularization and tissue remodeling in porous PEG hydrogel in vitro and in vitro. Both in vitro and in vivo studies showed that vessel invasion was pore size dependent. In addition, a thin layer of inflammatory tissue was observed between PEG hydrogel and blood vessels that formed within the gels. This layer suggested that inflammatory cells, not vascular cells, interacted with the surface of the material. This suggests that peptides covalently incorporated within PEG may not directly interact with endothelial cells (ECs) following implantation. The porous PEG hydrogels were very stable in vitro and in vivo and did not exhibit any signs of degradation. Hydrogels used in tissue engineering need to exhibit controlled degradation. In order to address the stability of PEG hydrogels, porous hydrogels were rendered using degradable PEG-co-(L-Lactic acid) diacrylate PEG-PLLA-DA. This polymer is degraded via hydrolysis of the PLLA chains. The porous PEG-PLLA-DA hydrogels were generated by solvent casting, photopolymerization, and particulate leaching. The influence of polymer conditions on the architecture, degradation, and mechanical properties of the hydrogels were investigated in vitro. The hydrogels were found to exhibit autofluorescence that allowed for the unique ability to nondestructively image hydrogel structure under fully swelled conditions using confocal microscopy. Initial pore size was a function of particulate size and independent of polymer concentration. Interestingly, pore size remained stable though out the study, and was not a function of degradation. In addition, degradation time of porous PEG-LLA-DA hydrogels was influenced by polymer concentration. Compressive modulus was a function of polymer concentration and pore size and decreased during hydrogel degradation. The incorporation of cell adhesion sequences into the hydrogel showed that they can support cell adhesion with morphology varying with pore size. This technique could be used to tailor porous biodegradable scaffolds for tissue engineering applications. In the final portion of this thesis a poly-lysine (PLL) molecule was synthesized in order to allow clustering of adhesion sequences in PEG hydrogels. Clusters of peptide sequences have been shown to enhance cell interactions with substrate surfaces. The sequence was synthesized and purified by high performance liquid chromatography (HPLC) and characterized by mass spectrometry. The side chains of the PLL molecule was used to attach peptide sequences. Cysteine contained within the PLL allowed incorporation into the PEG hydrogel by mixed mode polymerization. Cells were observed to adhere to hydrogels containing the RGD clusters and not to the control gels. The results presented here describe various techniques that can be used to optimize the design of polymer scaffolds for tissue engineering. In addition, the data provide insight into the process of vascularization in porous hydrogels and the influence of synthesis conditions and degradation on properties of porous hydrogels. Future studies should investigate the optimization of these material techniques for control of neovascularization within PEG hydrogels for tissue engineering applications.
Ph.D. in Biomedical Engineering, December 2011
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Title: DEVELOPMENT OF NANOPARTICLE APPLICATIONS IN CELL IMAGING, BIOASSAY AND REACTIVE OXYGEN SPECIES DETECTION BASED ON SURFACE-ENHANCED RAMAN SPECTROSCOPY
Creator: Yiming, Huang
Date: 2011-08, 2011-07
Description: After mid-1970, the exploration of surface-enhanced Raman scattering (SERS) has been studied by many research groups. Compared to traditional...
Show moreAfter mid-1970, the exploration of surface-enhanced Raman scattering (SERS) has been studied by many research groups. Compared to traditional Raman spectroscopy, enormous cross section of molecules can be obtained in SERS by placing the molecules within the electromagnetic field present in metal surfaces. This enhancement is due to resonance between the optical field and surface plasmon of the metal substrate. Nanoshells which are composed of a silica core and a thin gold shell can greatly enhance Raman scattering without the need to pre-aggregate the particles, due to their tunable optical property. In our study, we synthesized nanoshells as our SERS substrates for Raman tags. The stability of nanoshells coated with three different self-assembled monolayers containing poly(ethylene glycol) (PEG) molecules has been studied. Probes with Raman active PEG molecules have been delivered and imaged in macrophage cells and MCF7 cells, based on SERS technique. The benefits of this imaging technique we developed here are: 1) it is faster; 2) it requires less preparation; 3) it can provide the information of nanoshells in a semi-quantitative way in vitro. We also developed a rapid and easy-to-execute half-sandwich bioassay for the detection of low volumes (< 2 μL) of antigens on nitrocellulose membrane, based on SERS. Multiple antibodies with MW from 18.2 kDa to 170 kDa were bioconjugated to polymers and grafted to nanoshell surface to detect antigens on the membrane. SERS-based biosensors were tagged with Raman active PEGs for recognition and quantification. Here, the bioassay showed great sensitivity to very low concentration x viii of antigens and multiplexed testing have been successfully conducted on different antigens simultaneously. Moreover, SERS-based novel reactive oxygen species (ROS) sensors were designed by establishing mixed-monolayer consisting of poly(ethylene) glycol thiol (PEGSH) and either 4-nitrobenzenethiol (4-NBT) or 4-mercaptophenol (4-MP) on the surface of nanoshells. By analyzing the changes in the molecular Raman spectrum, we were able to track the production of hydroxyl radicals in low concentrations (~ 10 μM). The sensors have been delivered into the cells and did not show significant oxidative stress to the cells. Therefore, these designed sensors are very promising for tracking ROS produced by cells when they are under oxidative stress.
Ph.D. in Chemistry, July 2011
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Title: A UNIFIED BOUNDARY CONTROL LAW FOR DC-DC CONVERTERS USING A NORMALIZED STATE PLANE
Creator: Nie, Yue
Date: 2015, 2015-05
Description: This thesis proposes a unified boundary control law for DC-DC converters (Buck, Boost, and Buck-Boost) which improves both the transient and...
Show moreThis thesis proposes a unified boundary control law for DC-DC converters (Buck, Boost, and Buck-Boost) which improves both the transient and steady state response in comparison to boundary control laws using first or second order switching surface. A new set of switching zones on normalized state plane are defined to decide switching behavior every sample period. Additionally, non-ideal operations and a parameter self-adaptive algorithm are proposed and verified in simulation. The parameter self-adaptive algorithm enhances the system robustness and reduces the parameter sensitivity. The transient bandwidth for the load disturbance rejection and command tracking approaches the physical limits of DC-DC converters. Simulation results are presented to illustrate the major benefits of the proposed uni ed boundary control law.
M.S. in Electrical Engineering, May 2015
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Title: PROPOSITION AND EVALUATION OF A NEW DAMPER, CALLED ROTATIONAL CYLINDRICAL FRICTION DAMPER (RCFD)
Creator: Divani, Abbass
Date: 2013, 2013-12
Description: The objective of this study is to propose and evaluate an innovative frictional damper for structural systems, called Rotational Cylindrical...
Show moreThe objective of this study is to propose and evaluate an innovative frictional damper for structural systems, called Rotational Cylindrical Friction Damper (RCFD), which does not bear limitation of previously proposed systems and yet maintains their advantages. Different kinds of energy dissipaters have been studied and used in structural systems in recent years. They perform more effectively compared to structures without any energy dissipater. Each of previously employed devices has its advantages and limitations. In this report, applicability of previous energy dissipaters will be investigated; then the proposed damper, RCFD, will be introduced, and the performance of RCFD will be evaluated under lateral load using ABAQUS software. RCFD consists of a shaft, a cylinder and proper assembly of braces so that the bracing members make the cylinder and shaft move in opposite circular directions under defined load. The assemblage of braces depends on type of bracing system that is employed. When load in bracing member exceeds the buckling load of the member, it overcomes the friction between the shaft and inner surface of the cylinder and while providing the ductility demand of the structure, it absorbs the energy of the seismic load, and it will work like a safety valve to protect main structural members from inelastic deformation. In spite of other types of frictional dampers, RCFD does not use and reduces the construction cost of high strength bolts. There is no limitation for the size and fitness of the bracing members more than that is for conventional design of braced frames. When we prove the performance of RCFD, some of the requirements of conventional design such as requirement of section F2 of Seismic Provisions for Structural Steel Buildings, AISC 341-10, will be eliminated. The pressure needed for developing friction is provided by heating the shaft and placing it into the cylinder with slightly smaller xiii diameter. It is simple to design and construct and does not have the limitation of other kinds of frictional damper systems. It can also be installed with little or no modification on any kind of Braced Frames or to retrofit Moment Frames. In this study, RCFD will be installed and evaluated on an Inverted V Concentrically Braced Frame, although installation of the RCFD on X Braced frame will be illustrated.
M.S. in Civil Engineering, December 2013
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Title: 35TH BRONZEVILLE·IIT SOCIAL CONDENSER
Creator: Hyesun, Jeong
Date: 2012-11-19, 2012-12
Description: The transit station at IIT is mono-functional, lacking connections to place or programs that engage flows of people passing in and out of the...
Show moreThe transit station at IIT is mono-functional, lacking connections to place or programs that engage flows of people passing in and out of the neighborhood. Due to this fact, campus areas around the transit station become desolate and lackluster giving no motivation for people to remain at the station other than just to take train and bus. IIT’s campus lacks engagement with Bronzeville, although both the institution and neighborhood share the transit station. My proposal for these problems is to design a transit station and cultural complex that provides a social condenser for the larger community of Bronzeville. This will create a rich mixture of programs and amenities to be shared by both audiences
M.S. in Architecture, December 2012
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Title: DEVELOPMENT OF A NEW EMERGENCY EVACUATION SYSTEM FOR MINES
Creator: Qian, Qingyi
Date: 2011-08, 2011-07
Description: Underground mining is a very high risk industry. There are many potential hazards in the underground mining these include fire, explosion,...
Show moreUnderground mining is a very high risk industry. There are many potential hazards in the underground mining these include fire, explosion, inundation, roof collapse, toxic gases, chemical pollution, etc. Over past centuries, in US alone, more than 100,000 miners lost their life in different accidents. The primary safety methods used in underground mines concentrate on the monitoring of the hazardous gases, fire detection and ventilation. Using advanced instruments and monitoring techniques have significantly reduced the accidents in the modern mines. However despite the advancement of these monitoring facilities, accidents still occur in underground mining annually around the world, and many miners were killed because they were trapped and unable to escape due to blocked of exit access. This thesis describes a new development of an emergency evacuation system in underground mines and analyzes the advantages and disadvantages of the system. It is expected that the new system will greatly improve the emergency exit methods and save more lives in the future. The new emergency evacuation system consists of vertical concrete mineshaft, high capacity mineshaft elevators, surface terminal and underground support structures. In addition, the study of numerical simulation was carried out to observe the ground response during excavation. A typical ground profiles for underground mining in south part of China was used in this analysis. The results selected from shaft excavation simulation indicate that fluid drilling method effectively prevents the soil around mineshaft from collapse hazard. Compared to soil strength, soil stiffness has a significant influence on the soil response induced by excavating shafts.
Ph.D. in Civil Engineering, July 2011
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Title: CELL-MATRIX INTERACTIONS IN ADIPOSE TISSUE FUNCTION
Creator: Vaicik, Marcella K.
Date: 2015, 2015-07
Description: The overall goal of this work is to apply in vivo and in vitro models to study the basement membrane protein laminin α4 (lama4) in adipocyte...
Show moreThe overall goal of this work is to apply in vivo and in vitro models to study the basement membrane protein laminin α4 (lama4) in adipocyte function. Adipose tissue accumulation, lipogenesis, and structure were examined in mice with a null mutation of the lama4 gene (Lama4−/−) and compared to wild-type animals (Lama4+/+). The Lama4−/−mice phenotype was investigated to evaluate if the differences were due specifically to the adipose tissue function. Physical activity and food intake does not differ between Lama4+/+ and Lama4−/− mice. However, Lama4−/− mice have a significantly increased metabolic rate at 25°C and 16°C compared to Lama4+/+ mice. In contrast, in thermoneutral conditions at 30°C both Lama4+/+ and Lama4−/− mice exhibit equivalent metabolic rates. Interestingly, when room temperature housed mice fat pads were evaluated with immunohistochemistry, Lama4−/− mice exhibit significantly increased UCP-1 expression in subcutaneous adipose. These results suggest that beiging, white to brown adipocytes, in subcutaneous adipose tissue in Lama4−/− mice may lead to decreased adipose tissue accumulation and improved metabolic function. While animal models indicate the absence of lama4 results in more beiging in subcutaneous adipose tissue, an in vitro tissue engineered model was developed to study the adipocyte function in a controlled microenvironment. Primary cell spheroids developed from Lama4+/+ and Lama4−/− were incorporated into synthetic poly(ethylene glycol) (PEG) hydrogels within a range of stiffnesses. When the cells were given the same chemical cues their functions differed depending upon microenvironment stiffness. Beige function in adipocyte cells in 3D can be influenced by matrix stiffness. In conclusion, the laminin alpha 4 basement membrane protein absence in adipose tissue results in adipocyte functional changes in vivo. The Lama4−/− mice have resistance to diet induced weight gain and increased metabolic rate at room temperature and when cold challenged. The Lama4−/− mice had increased beiging in the subcutaneous depot. Additionally, a tissue engineered model was developed to further study cell-ECM interactions first identified in an animal model. These in vivo findings and the engineered model of adipose tissue have great potential for studying obesity and other adipose related diseases. Future work will require continued interdisciplinary collaboration towards the successful identification and screening of novel therapeutics using engineered tissue models.
Ph.D. in Biomedical Engineering, July 2015
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Title: SYSTEMATIC FINANCE: ESSAYS ON ETHICS, METHODOLOGY AND QUALITY CONTROL IN HIGH FREQUENCY TRADING
Creator: Van Vliet, Benjamin Edward
Date: 2012-04-18, 2012-05
Description: A firm is in a state of strategic competitiveness if it has a plan that it rationally and responsibly believes is capable of success. In the...
Show moreA firm is in a state of strategic competitiveness if it has a plan that it rationally and responsibly believes is capable of success. In the age of automation, what justifies a trading firm’s belief in its strategic competitiveness has changed. Rational and responsible belief in the capability of the firm’s trading strategies can be justified by a prudent process that defines conditions for both initial and sustained belief. The process of developing trading systems is itself systematic and a source of competitive advantage. In this thesis, I present three chapters that address strategic competitiveness in automated trading—ethics, methodology and quality control. These chapters examine responsibility, and develop processes for both initial and sustained belief in the competitiveness of trading systems and the trading firm.
Ph.D. in Management Science, May 2012
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Title: An Examination of the Bidirectional Associations between Sleep Quality and Binge Eating Using Ecological Momentary Assessment
Creator: Johnson, Nicole Kathryn
Date: 2024
Description: Binge eating (BE) is associated with impairments in psychosocial functioning and poor treatment response, and BE commonly occurs in at-risk...
Show moreBinge eating (BE) is associated with impairments in psychosocial functioning and poor treatment response, and BE commonly occurs in at-risk populations including female adults. BE occurs transdiagnostically across the ED spectrum and maintains other ED behaviors (e.g., dietary restriction, purging). Thus, it is important to research factors that maintain BE over time. Research suggests that poor sleep quality (e.g., difficulty falling or staying asleep, restless sleep) could contribute to BE persistence due to potential bidirectional associations between sleep quality and BE and that negative affect (NA) and the time that BE occurs could explain the BE-sleep association. To extend this research, the current study used ecological momentary assessment (EMA) to examine 1) between- and within-person bidirectional associations between BE and sleep quality and 2) if momentary NA (assessed between sleep and BE) mediates and if the timing of BE moderates the within-person BE-sleep quality associations. For the current study, adults assigned female at birth (N=57) with recurrent BE (at least twice a week for the past three months) self-reported BE, sleep quality, and NA at baseline and over a 14-day EMA period. Hierarchical regression analyses found that higher BE severity at baseline significantly predicted lower sleep quality averaged over the EMA period (p=0.02) but was only approaching significance after controlling for baseline sleep quality and depression (p=0.06). Between-person aggregated BE severity over the EMA period was not significantly associated with aggregated sleep quality and sleep quality at baseline and aggregated was not significantly associated with aggregated BE severity or more frequent BE over the EMA period (p’s>0.05). Multilevel models found significant bidirectional associations within-person higher BE severity and poor sleep quality, such that higher BE severity predicted worse sleep quality later that night (p=0.03) and worse sleep quality predicted higher BE severity later that day (p=0.03). In contrast, poor sleep quality did not significantly predict an increased likelihood of BE and there were not significant differences in sleep quality between BE and non-BE days (p’s>0.05). Multilevel modeling also found that intermediate ratings of NA did not mediate the within-person associations between sleep quality and BE severity, sleep quality did not mediate the within-person association in which NA predicted BE severity, and BE timing did not significantly predict sleep quality or moderate within-person BE severity predicting poor sleep quality (p’s>0.05). This study was the first to use EMA to test the bidirectional associations between BE and sleep quality while also accounting for NA and BE timing. Results suggest that among AFAB adults BE severity may lead to worse sleep quality, independent of NA and BE timing, and worse sleep quality may lead to higher BE severity on days with BE, independent of NA. Findings from the current study support integrating interventions for sleep disturbances into treatments for BE-spectrum EDs.
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Title: A dual-aperture fluorescence ratio method to quantify depth of fluorescence for intraoperative margin assessment in oral squamous cell carcinoma solid tumor resections
Creator: Rounds, Cody C.
Date: 2024
Description: Oral squamous cell carcinoma (OSCC) is a significant contributor to the global cancer burden, with surgical resection being the primary course...
Show moreOral squamous cell carcinoma (OSCC) is a significant contributor to the global cancer burden, with surgical resection being the primary course for treatment. However, achieving clear surgical margins remains a challenge owing to the complex anatomy of the head and neck, and it is estimated that as many as 30% of patients are sent home after surgery with residual cancer. Current surgical margin assessment techniques, such as post-operative histopathology and intraoperative frozen section analysis, either take too long to complete in an intraoperative time frame or have limitations in accuracy and efficiency. Fluorescence-guided surgery (FGS) has emerged as a promising approach to enhance intraoperative surgical margin assessment, with a few clinical research groups in the US and the Netherlands demonstrating the potential of epidermal growth factor receptor (EGFR)-targeted FGS in OSCC to identify at least a fraction of insufficient margins, intraoperatively. However, existing methods have demonstrated limited accuracy in detecting so-called “close” margins (cancer is found between 1-5 mm from the surgical margin), which are associated with an increased risk of local recurrence compared to “clear margins (>5 mm of healthy tissue at the surgical margin).This thesis evaluated the potential for a dual-aperture fluorescence ratio (dAFR) imaging approach to be used to improve the accuracy of close margin detection and localization in OSCC surgical margins. The dAFR technique involves dividing high numerical-aperture (NA) fluorescence images by low NA images taken from the same point-of-view, creating a ratio image that has been hypothesized to be correlated with depth of the fluorescence inclusion, in a manner that is insensitive to variability in tissue optical properties, in sub-diffuse photon propagation regimes. The validity of the hypothesis that dAFR signals can be correlated directly to depth of fluorescence in OSCC surgical margins was first explored in a set of Monte Carlo photon propagation simulations. The Monte Carlo simulation framework was also used to (1) guide the selection of the optimal range of numerical apertures (NAs) to use for the wide and narrow apertures for dAFR, (2) for evaluating the accuracy and precision of dAFR depth estimation across varying tissue optical properties, and (3) for evaluating dAFR depth estimation accuracy when tissue optical properties were heterogeneous, as would be expected in clinical OSCC margin imaging applications. A prototype dAFR-capable imaging system was designed based on the findings of the simulation work and was constructed considering factors such as accessibility, rapid imaging capability, safety, field-of-view, and image quality. The performance of the constructed system was then first evaluated through phantom experiments, where resinous materials with optical properties matching those of biological tissue and fluorescence at various depths were used to experimentally demonstrate the depth sensitivity of dAFR compared to single-aperture fluorescence (sAF) imaging. The dAFR system was then deployed to a clinic at the University Medical Center Groningen (UMCG) in The Netherlands to be tested out in a clinical pilot study. There, the surgical margins of 3 OSCC patients were imaged with our dAFR approach and the more conventional sAF approach and the correlations between dAFR and sAF measurement to histopathology measured margin thickness was evaluated at 12 different margin locations from 3 patients. In this pilot group of patients, dAFR provided significantly higher accuracy in detecting close margins compared to sAF (p < 0.02), with an area under the receiver operating characteristic curve (AUC of the ROC) of 1.0 for close margins. These results embody the first clinical demonstration of close margin detection in an intraoperative timeframe (< 2 min of imaging). Though the sample size was small (n = 3), these preliminary results have been used to leverage funding of the ongoing development of a second system prototype and the commencement of an 80-patient clinical study over the next 5 years. Other future research directions include the optimization of imaging hardware, correction for surface topography, expansion of clinical studies to other cancer types, integration with other imaging modalities, development of user-friendly interfaces, automated margin detection and localization of insufficient margins, and enhanced co-registration of margin localization in excised margins with in vivo anatomical structures to guide potential extended resection.
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Title: Goal Orientation, Personality, and Time and Their Influences on Profiles of Self-Regulated Learning
Creator: Nguyen, Derek Khai
Date: 2024
Description: This exploratory study investigates profiles of self-regulated learning (SRL) and expands on a gap in previous research. Previously found...
Show moreThis exploratory study investigates profiles of self-regulated learning (SRL) and expands on a gap in previous research. Previously found profiles were summarized, replicated, and differences among profiles in academic outcomes, personality, and goal orientation were examined. Additionally, these relationships were examined longitudinally to investigate whether personality or goal orientation predicted stability of profile membership. Four profiles were found using latent profile analysis in a participant pool of 270 undergraduate and graduate students: a very high SRL profile, a high SRL profile, an unmotivated but strategic SRL profile, and a low SRL profile. One-way ANOVA revealed grades did not differ significantly among profiles. Regression analysis found LGO, openness to experience, conscientiousness, and extraversion were significant predictors of SRL profile. Latent transition analysis was used for longitudinal analysis. Over time, participants were more likely to move from profiles utilizing more SRL to profiles of lower SRL. Generally, openness to experience, extraversion, agreeableness, and neuroticism predicted change more than stability, while PPGO predicted stability more than change
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Title: EARLY DETECTION OF MAINTAINABILITY ISSUES IN MEP SYSTEMS USING BIM
Creator: Barbarosoglu, Bahadir Veli
Date: 2018, 2018-05
Description: The terms maintainability and maintenance are interrelated and often perceived to be difficult to distinguish from each other. Maintainability...
Show moreThe terms maintainability and maintenance are interrelated and often perceived to be difficult to distinguish from each other. Maintainability refers to the measures and actions taken during the design phase in order to assure that the building components and the system to which it belongs can be easily maintained at minimum downtime and cost. On the other hand, maintenance refers to the measures and action taken during the operation phase in order to keep the components at the desired operational condition. The variance between designers’ and facility managers’ priorities concerning maintainability creates a gap between the design and operation phases. Maintainability is not often considered in design nor is it a priority for designers. Designers consider equipment access to be one of the least important factors related to maintenance. However, design-related maintainability issues such as equipment access problems make maintenance activities impractical if not impossible in facility operation, and increase the life cycle costs of facilities. These issues can be detected in the design phase if an appropriate tool is available, and can prevent maintenance-related problems in the operation phase. This research aims to bridge the gap between design and facility management by developing and deploying a BIM tool that brings a facility management perspective into design, and allows designers to inject maintainability considerations into the design phase. In this study, the building and construction codes and standards adopted and published by the local governments of the United States were investigated in order to identify maintainability standards related to geometric design and parametric information of building components. Parametric rule sets related to maintainability were established according to the codes and standards. From the “equipment access” perspective, a maintainability checking algorithm that can be easily customized for any building component and its rule sets was developed. In order to demonstrate the operation of the algorithm in 3D design view, the algorithm was customized for a particular piece of equipment, codded in C# programing language, and implemented as an add-in called “Maintainability Checker” to the most commonly used BIM software: Revit. A video clip of the demonstration was embedded into a questionnaire, and the questionnaire was administrated to designers and facility managers in order to validate the potential benefits of “Maintainability Checker”. A comparative analysis of designers’ and facility managers’ opinions towards maintainability and “Maintainability Checker” was conducted using SPSS. The survey results indicate that the gap between the design and post-construction phases does exist. However, the survey results also indicate that “Maintainability Checker” can bridge the gap by allowing designers to produce a better design that improves equipment maintenance access and workplace safety, facilitates the cleaning and repair of building components, reduces the number of reworks, improves the efficiency of the commissioning process, and reduces the time spent on maintenance activities, all without increasing the workload of designers. The construction industry should consider an automated maintainability check to be an essential part of the design process, create/adopt design for maintainability standards for every building component that can possibly be in a structure, and use them within BIM tools.
Ph.D. in Civil Engineering, May 2018
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Title: THE PARADOX OF COMMUNICATION TECHNOLOGY IN THE WORK-FAMILY INTERFACE
Creator: Ishaya, Nahren M.
Date: 2018, 2018-05
Description: The aim of the present study was to investigate the “double-edged sword” nature of communication technology in its impact on the work-family...
Show moreThe aim of the present study was to investigate the “double-edged sword” nature of communication technology in its impact on the work-family interface. Communication technology has many wonderful advantages, one of which is the flexibility that it provides employees with where and when work is completed. The flipside, though, is that communication technology allows employees to be available and accessible at all times. The purpose of this study was to assess the impact of (1) accessibility and availability through communication technology; and (2) flexibility through communication technology, on the experience of work-to-family conflict, family-to-work conflict, and work-family balance. The study utilized Conservation of Resources theory and Job-Demand Control model as its basis for examining how the relationship between work and family demands and work-family interface outcomes are impacted by the two communication technology variables of interest in this study. Qualtrics Panels were used to recruit 405 working adults in the United States across various industries to complete an online survey. To help address single source bias, employees were asked to invite their spouse/partner to complete a survey to assess levels of work-family interface of the employee from the spouse/partner perspective. Hierarchical moderated regression analyses were used to test the hypotheses. The results indicated that employees who perceive that communication technology provided greater flexibility in the work and family domains experienced less work-to-family conflict, and family-to-work conflict, respectively. Further, employees who perceived that greater expectations to be available and accessible to others in their work and family domains experienced greater work-to-family conflict and family-to-work conflict, respectively. Accessibility and availability expectations exacerbated the association between demands and work-to-family conflict in both the work and family domains. Communication technology flexibility was found to buffer the effect of family overload in the experience of family-to-work conflict. The theoretical and practical implications of these findings and potential directions for future research are discussed.
Ph.D. in Psychology, May 2018
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