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Title: Investigation of time of combustion in a gas engine cylinder
Creator: Enander, E. H., Gaylor, W. S.
Date: 2009, 1906
Publisher: Armour Institute of Technology
Description: http://www.archive.org/details/investigationoft00enan
Thesis (B.S.)--Armour Institute of Technology

Title: An investigation of the various properties of sand as affecting its use in concrete and mortar
Creator: Altman, Eugene E
Date: 2009, 1916
Publisher: Armour Institute of Technology
Description: http://www.archive.org/details/investigationofv00altm
Thesis (B.S.)--Armour Institute of Technology;Bibliography: leaf 70

Title: An investigation of the tar by-product of the water gas industry
Creator: Harper, Robert B., Fash, Ralph H.
Date: 2009, 1905
Publisher: Armour Institute of Technology
Description: http://www.archive.org/details/investigationoft00harp
Thesis (B.S.)--Armour Institute of Technology

Title: THE DEVELOPMENT OF AN INSTRUMENT TO EVALUATE TEACHERS’ CONCEPTS ABOUT NATURE OF MATHEMATICAL KNOWLEDGE
Creator: Kean, Lesa L.
Date: 2012-12-10, 2012-12
Description: While there does seem to be widespread consensus that teachers’ beliefs and concepts influence the way they teach, even the most recent...
Show moreWhile there does seem to be widespread consensus that teachers’ beliefs and concepts influence the way they teach, even the most recent international studies suggest that research-based evidence for this consensus is limited. In an effort to enlarge and enhance the pool of evidence that shows specific relationships between teacher beliefs and practice, the present author undertook to write an attitude survey and interview protocol that identifies and distinguishes teachers’ concepts on eight different aspects of NOMK. Such a survey seems to be a natural first step to providing evidence for the larger question of which beliefs correlate to what teacher behaviors. Eight NOMK aspects were identified and defined based on a review of over 68 resources including twelve that contained an existing assessment addressing NOMK concepts. While superficial inspection of the assessments referenced may suggest that the best solution may be to use an existing assessment or to compile a list of items from these various assessments and use that to assess NOMK, the researcher suggests four major issues that would suggest otherwise. The items of the assessment and the assessment as a whole were validated through several steps. First, the author started with over 40 survey items, distributed evenly over her eight aspects and including both Likert-type and open-ended items. Second, the items were randomized and distributed to practicing mathematics teachers for their feedback. Third, the items were revised and sent back out to teachers for additional feedback. Fourth, the resulting survey was piloted with over 20 community college teachers. Fifth, their responses were coded, and the open-ended items were coded by xii rubric and confirmed by a second coder. Sixth, the survey was revised once again and piloted to another sample of 20 with similar analysis. Finally, she conducted several forms of qualitative and quantitative analysis to cull down the items to those that produced the most valid and reliable survey items set possible. The resulting survey addresses six of the eight aspects proposed by the researcher and includes both Likert-type and open-ended items intended to be confirmed and clarified through interview. The researcher suggests further research be done in order to design items that validly and reliably identify teachers’ concepts of NOMK on the remaining two aspects.
PH.D in Mathematics Education, December 2012
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Title: SIMULATION AND DEVELOPMENT OF A CLINICAL ANALYZER-BASED IMAGING SYSTEM
Creator: Majidi, Keivan
Date: 2013, 2013-12
Description: The analyzer-based phase-sensitive X-ray imaging method (ABI) is emerging as a potential alternative to conventional radiography. ABI...
Show moreThe analyzer-based phase-sensitive X-ray imaging method (ABI) is emerging as a potential alternative to conventional radiography. ABI simultaneously generates a number of planar images containing information about scattering, refraction and absorption properties of the object. These parametric images are acquired by sampling the angular intensity profile (AIP) of an X-ray beam passing through the object at different positions of the analyzer crystal. Like many of the modern imaging techniques, ABI is a computed imaging method (meaning that the images are calculated from raw data). Therefore, the noise in ABI depends on the imaging conditions such as source flux, number of the analyzer positions, and the analyzer positions themselves as well as on the estimation method of the parameters. In the first part of this thesis, we use the Cramer-Rao lower bound to quantify the noise in ABI images and then investigate the effect of different analyzer-sampling strategies on this bound. The CRLB is the minimum bound for the variance of an unbiased estimator and defines the best noise performance that one can obtain regardless of which estimation method is used to estimate ABI parametric images. We will then use this bound to evaluate three ABI methods: Multiple-Image Radiography (MIR), Diffraction Enhanced Imaging (DEI) and Scatter Diffraction Enhanced Imaging (S-DEI). The proposed methodology can be used to evaluate any other ABI parametric image estimation technique. Synchrotron radiation has been the main source for experimental ABI and developing its methodologies, therefore the ABI application to clinical imaging has been very limited. It is inevitable to use conventional X-ray sources for ABI in order to utilize xii the technique in the clinical applications, however, due to the limited intensity of these sources and their finite source size, developing such systems is very challenging. In the second part of this thesis, we use computer simulations to understand the above challenges better. We measure the properties of this imaging system such as flux and point-spread function for various design parameters and discuss how to find an “optimal” setup based on these properties. The optimality of an imaging setup depends on the specific application that one wants to perform using the system; however, the results and discussions in this section layouts a design procedure for clinical ABI systems. In the last part of this thesis we review the steps we took in the Advanced X-ray Imaging Laboratory (AXIL) toward developing a clinical ABI system.
PH.D in Electrical Engineering, December 2013
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Title: GOTTA EAT TO LIVE, GOTTA STEAL TO EAT: THE INVESTIGATION OF SERIOUS DISRUPTIVE BEHAVIOR, TEMPERAMENT, AND EXECUTIVE DYSFUNCTION AMONG HOMELESS YOUTH
Creator: Kaszynski, Katie
Date: 2014, 2014-07
Description: Background: Homeless youth are at risk for many adverse outcomes, including poor physical health, traumatic experiences, victimization, poor...
Show moreBackground: Homeless youth are at risk for many adverse outcomes, including poor physical health, traumatic experiences, victimization, poor academic achievement, cognitive deficits, psychopathology, and substance use. Research demonstrates that these individuals engage in substantial disruptive behavior (e.g., stealing, dealing drugs, breaking and entering, engaging in prostitution), which further increases their risk of negative outcomes. Individual factors, including innate temperament and executive functioning skills have been shown to relate to one another and be independently related to behavior problems, as evidenced by research investigating housed youth. Homeless youth are shown to exhibit poor effortful control, high distress, executive dysfunction, and substance abuse; factors of which have not been fully examined in relationship to persistent behavior problems as reflected in antisocial personality disorder (ASPD). Study Aim: The current study evaluated the association between temperament, executive functioning, and substance use disorders in their relation to the likelihood of meeting criteria for ASPD among homeless youth (ages 18-22). It was hypothesized that these variables would significantly relate to meeting criteria for ASPD in this population. Procedure: 87 homeless individuals (mean age = 19.27) who were residing at a homeless shelter at the time of the study (in Chicago or Los Angeles) participated over the course of two testing sessions. Each individual completed measures of ASPD and substance use disorders (MINI), temperament (ATQ), and executive functioning (D-KEFS), among other measures that are part of a larger studying conducted at University of Chicago Medical Center (UCMC). Results: Results suggested that temperament (specifically effortful control) executive dysfunction (specifically cognitive shifting), and substance use disorder (specifically substance abuse) were significantly related to the likelihood of a homeless individual meeting criteria for ASPD. Youth who showed poorer effortful control, better ability to shift attention between sets of information, and substance abuse were at a greater likelihood of meeting criteria for ASPD. Conclusions: These findings indicate that aspects of temperament, specific executive skills, and substance abuse are important variables in determining the likelihood of ASPD among a population of homeless individuals. Clinical implications, limitations, and suggestions for interventions are discussed.
Ph.D. in Psychology, July 2014
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Title: THE VAPORIZATION PHENOMENA OF FUEL DROPLETS EXPOSED TO ASYMMETRIC RADIANT HEATING USING PLANAR LASER-INDUCED FLUORESCENCE
Creator: Ammigan, Kavin
Date: 2012-04-17, 2012-05
Description: Droplet vaporization under asymmetric conditions is prevalent in many combustion related devices where fuel droplets may either experience...
Show moreDroplet vaporization under asymmetric conditions is prevalent in many combustion related devices where fuel droplets may either experience asymmetric thermal radiant heating or travel in velocity and temperature gradients. Asymmetric radiant heating is particularly common in spray flames, counter-flow diffusion flames, regions close to the walls of conventional combustion chambers and more importantly in liquid-fueled microcombustors. In this study, experiments are carried out to observe how droplets vaporize when exposed to asymmetric radiant heating. The experimental set-up consists of applying radiant heating, through a radiant panel heater, to one face of a monodisperse droplet stream while using the planar-laser induced fluorescence (PLIF) diagnostic tool to reveal the spatial vapor distribution around vaporizing droplets. Since most fuels are made up of multiple components, bicomponent droplets are also investigated. Pure acetone droplets as well as mixtures of acetone/alkanes (octane and hexane) and acetone/alcohols (ethanol and 2-propanol) droplets are investigated. Results in the form of PLIF images, reveal asymmetric vapor distributions around the droplets with the apparent induction of Stefan flow from the irradiated droplet surface. Such phenomena have not previously been reported in the literature and have relevance to the overall fuel vaporization process as well as subsequent ignition and pollutant formation processes. To further investigate the experimental results, a convective and radiative heat transfer model is employed to simulate the droplets under corresponding experimental conditions. Results from the model show convective cooling and a strong thermal radiation absorption near the droplets’ surface. The induced asymmetric Stefan flow observed experimentally is therefore a consequence of the high thermal radiation absorption at the droplets’ surface. This study gives both experimental and theoretical results of the vaporization phenomena of asymmetrically irradiated fuel droplets with varying compositions, diameters and irradiation temperatures.
Ph.D. in Mechanical and Aerospace Engineering, May 2012
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Title: ROBUST OPTIMIZATION OF UNIT COMMITMENT PROBLEM WITH RENEWABLE RESOURCES AND ELECTRICAL ENERGY STORAGE
Creator: Kashyap, Prakash
Date: 2016, 2016-12
Description: The Chinese proverb |\To be uncertain is to be uncomfortable, but to be cer- tain is to be ridiculous" |mention in the preface of the book...
Show moreThe Chinese proverb |\To be uncertain is to be uncomfortable, but to be cer- tain is to be ridiculous" |mention in the preface of the book Robust Optimization by Aharon Ben-Tal, Laurent El Ghaoui and Arkadi Nemirovski, truly capture the cer- tainty of uncertainty in every walk of life. However, it is human endeavor to manage uncertainty by properly engineered system. Power system is no exception. Uncer- tainty with load forecasting and contingencies such as generator and/or transmission line outages impose reliability and security issue with power system operation. In wholesale market, tools like spinning reserve and non-spinning reserve are used by ISO/RTO to mitigate severe consequences of such uncertainties. With increased share of highly volatile renewable energy resources such as wind and solar power, price-based demand response and electric vehicle charging station, uncertainty in power system operation is going to be further aggravated. A scenario based stochastic approach instead of system reserve based deterministic approach is considered another solution to the problem. However, scenario based stochastic solution may miss some critical scenarios. Secondly, we may need a large number of scenarios to get a su ciently reliable solution. In recent years, robust optimization based security constrained economic dis- patch (SCED) and security constrained unit commitment (SCUC) have been explored by several researchers. This thesis explores implementation of robust optimization for secure and economical operation of power system in presence of renewable energy resources (RES) and electrical energy storages (EES).
M.S. in Electrical Engineering, December 2016
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Title: ANALYSIS AND CONTROL OF COMPRESSION-IGNITION AND SPARK-IGNITED ENGINES OPERATING WITH DUAL-FUEL COMBUSTION STRATEGY
Creator: Kassa, Mateos
Date: 2017, 2017-07
Description: In recent years, the implementation of a dual-fuel combustion strategy has been explored as a means to improve the thermal efficiencies of...
Show moreIn recent years, the implementation of a dual-fuel combustion strategy has been explored as a means to improve the thermal efficiencies of internal combustion engines while simultaneously reducing their emissions. The dual-fuel combustion strategy was introduced in compression ignition engines to control the combustion phasing by varying the proportion of two simultaneously injected fuels, and altering the combustion timing. The dual-fuel injection strategy also allowed to extend the load limitation of advanced combustion engines, since the two injected fuel ignite in succession reducing the high peak pressures that generally act as a limiting factor. In spark-ignited (SI) engine, the implementation of a dual-fuel combustion strategy serves as an alternative approach to avoid knock (the inadvertent auto-ignition of the fuel mixture). Although conventional engines rely on delaying spark timing to avoid knocking cycles (which significantly reduces the thermal efficiency), the dual-fuel SI engine rely on the simultaneous injection of a low knock resistance and high knock resistance fuel to dynamically adjust the fuel resistance to knock as required. The dual-fuel SI engine thereby successfully suppresses knock without compromising the engine efficiency. Despite the benefits of the dual-fuel combustion strategy, several challenges arise in its implementation, especially when it is implemented along with other advanced combustion strategy leveraging variable valve timing, exhaust gas recirculation, turbocharging, and so forth. This study explores some of these challenges and addresses them from a control standpoint. Cylinder-to-cylinder variations is identified as one of the main challenges. An in-cylinder oxygen estimation strategy and modification to the conventional fueling strategy are proposed as approaches to reduce the combustion variations. In SI engines, the valve dynamics in transient operations are shown to negatively impact the dual-fuel control strategy. The effect of the valve timing on knock propensity and the resulting effect on the fueling strategy is investigated. Finally, the dual-fuel SI engine relies on measurements of the combustion intensity to adjust the fuel split between the low RON and high RON fuel. The implementation of a conventional knock control is shown to be counterintuitive for dual-fuel SI engines due to the highly reactive nature of the controller and the deterministic approach that assumes cycle-to-cycle correlation of the combustion intensity. Statistical investigation of the combustion intensity metric is conducted to identify key properties that can be leveraged for more effective control strategy.
Ph.D. in Mechanical, Material and Aerospace Engineering
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Title: SLIP-LINK MODELING OF ENTANGLED POLYMERS: RHEOLOGICAL APPLICATIONS AND EXTRACTING FRICTION FROM ATOMISTIC SIMULATION
Creator: Katzarova, Maria
Date: 2016, 2016-05
Description: The Discrete Slip-link Model (DSM) is a robust mesoscopic theory that has great success predicting the rheology of flexible entangled polymer...
Show moreThe Discrete Slip-link Model (DSM) is a robust mesoscopic theory that has great success predicting the rheology of flexible entangled polymer liquids and gels. In the most coarse-grained version of the DSM, we exploit the university observed in the shape of the relaxation modulus of linear monodisperse melts. For this type of polymer we present analytic expressions for the relaxation modulus. The high-frequency dynamics which are typically coarse-grained out from the DSM are added back into these expressions by using a Rouse chain with fixed ends. We find consistency in the friction used for both fast and slow modes. Using these analytic expressions, the polymer density, the molecular weight of a Kuhn step, Mk, and the low-frequency cross-over between the storage and loss moduli, G' and G", it is now straightforward to estimate model parameter values and obtain predictions over the experimentally accessible frequency range. Moreover it has previously been shown that the two static parameters can be obtained from primitive path analysis of molecular dynamics simulations. In this work, two ways are shown for obtaining the friction parameter (i) from atomistic simulations of short chains using the free-volume theory, and (ii) from atomistic simulations of entangled chains by scaling the chain center-of-mass mean-square displacement from the slip-link model to that of the atomistic simulation. Futhermore three standing challenges for molecular theories of polymers (i) predictions for uniaxial extension of star-branched polymer melts (ii) predictions for blends of star-branched and linear chains and (iii) predictions for normal stress differences in start-up of shear and followoing cessation are addressed here using the DSM. Additionally the DSM is used to predict the mechanical properties of a cross-linked polydimethylsiloxane (PDMS) network swollen with non-reactive entangled PDMS solvent. These successful predictions strongly suggest that the observed rheological modification in the swollen blend arises from the constraint dynamics between the network chains and the dangling ends.
Ph.D. in Chemical Engineering, May 2016
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Title: ENACTMENT OF COMMON CORE STATE STANDARDS FOR MATHEMATICS: RELATIONSHIP BETWEEN TEACHERS’ CHOICES OF CURRICULUM, TEACHING, AND PROFESSIONAL DEVELOPMENT
Creator: Kartal, Ozgul
Date: 2015, 2015-07
Description: In response to perceived problems of the United States mathematics curriculum, the Common Core State Standards (CCSS) were developed under the...
Show moreIn response to perceived problems of the United States mathematics curriculum, the Common Core State Standards (CCSS) were developed under the leadership of the National Governor Association (NGA) and the Council of Chief State School Officers (CCSSO), and were released in 2010. As of the time of this study, forty-four states, the District of Columbia, four territories, and the Department of Defense Education Activity have adopted the CCSS. The CCSS for Mathematics (CCSSM) initiative has raised many research questions for the field concerning the quality, enactment, and effectiveness and impact of the standards. There is a great deal of concern, in particular, about the enactment of the standards, because􀁿as pointed out by Heck, Weiss, and Pasley (2011)􀁿if standards have not been well implemented in a particular setting, then failure or ineffectiveness shouldn’t be blamed on the standards. Various researchers identified the key components of a successful enactment of a set of standards as curriculum, assessment, professional development, and teachers and teaching practice (e.g., Confrey & Krupa, 2010; Goertz, 2010; Weiss et al., 2002; Wu, 2011b). Therefore, this research study focused on the enactment of the CCSSM, and analyzed the curriculum, teaching, assessment, and teacher professional development as the key components of the enactment process. This study focused on the state of Illinois which is one of the states that started fully implementing the new academic standards in the 2013-14 school year, and hence had ample preparation and trial time between the adoption and full implementation years. This study investigated the alignment between teachers’ choices of curriculum and CCSSM, and relation between the curriculum resources, professional development, and enactment of CCSSM. The focus of the study was on the content of basic algebra and concepts of solving equations and slope while investigating the alignment of enactment of the CCSSM. The sample was comprised of twelve 9th grade algebra teachers from six different schools in the state of Illinois. The criteria in selecting the schools were the geographic location of the schools, the types of the schools, the curricula used at the schools, and the professional development on CCSSM offered at the schools. Results of this study found that the curricula have limited alignment with CCSSM, and that teachers’ enactment of mathematical practices was affected by the availability of variety of standards for mathematical practices in their curriculum as well as professional development opportunities. The curricula provided opportunities for various mathematical practice standards throughout the content of basic algebra, but some practice standards were left out. Teachers provided opportunities for a subset of the standards that were present in the instructional segments of their curriculum. If not, they provided opportunities for practice standards as a result of acquisition from professional developments. The impact of professional development was most evident when teachers using the same curriculum differed in their enactment of the practices. This study portrayed the relations between (low/high) enactments of CCSSM, curriculum resources (aligned or not aligned), and professional developments. Many states and districts are just beginning to incorporate CCSSM into their math curriculum at the time of this study. Therefore, the findings of this study will guide them as they make their textbook, curriculum, and professional development choices and decisions. In addition, this research generated valuable knowledge that would be useful not only in improving the enactment of the CCSSM, but also improving the enactment of future sets of standards. There are implications for curriculum designers, administrators/school and district leaders, professional development designers, and teacher educators.
Ph.D. in Mathematics Education, July 2015
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Title: IRRITABILITY IN CHILDREN: SAME AS FRUSTRATION AND ANGER?
Creator: Kozy, Karyn Brasky
Date: 2013, 2013-12
Description: The primary aims of this study were four-fold. The first aim was to examine which of the three alternative models of irritability provided a...
Show moreThe primary aims of this study were four-fold. The first aim was to examine which of the three alternative models of irritability provided a better fit to the data. The second aim was to further refine the model of irritability by examining the gender and age invariance of the best-fitting models. After establishing which model showed the best fit, the third aim was to empirically examine the reliability and validity of the irritability scale that included items from both temperament and psychopathology scales. Finally, the fourth aim was to examine the rank-order stability and mean-levels of irritability between the ages of 4 and 6. Participants included a diverse, community sample of 796 children and their parents. Irritability, frustration, and anger were measured by selected items from temperament and psychopathology scales, including the Children’s Behavior Questionnaire (CBQ; Rothbart et al., 2001), Child Symptom Inventory (CSI; Gadow & Sprafkin, 1994, 1997), and Eyberg Behavior Inventory (ECBI; Eyberg & Pincus, 1999). Results indicate that the three-factor and two-factor measurement models were viable, alternative models at age 4. Contrary to expectation, neither the three-factor nor the twofactor models were invariant for both genders combined, or between the ages of 4 and 6. Based on the definition of irritability in the three-factor model, the irritability scale demonstrated adequate internal consistency, convergent validity, and divergent validity. Finally, the rank-order stability of irritability was in the moderate range during the period from preschool through kindergarten and formal school entry, but mean-levels of irritability did not differ across time. Implications of the findings and suggestions for future research are discussed.
PH.D in Psychology, December 2013
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Title: VALUE OF BATTERY STORAGE SYSTEM IN THE FEREQUENCY REGULATION MARKETS OF PJM AND CAISO
Creator: Khorsand, Shervin
Date: 2017, 2017-05
Description: With an increasingly urgent need to decrease our utilization of fossil fuels, renewable power sources such as wind and solar are being...
Show moreWith an increasingly urgent need to decrease our utilization of fossil fuels, renewable power sources such as wind and solar are being incorporated in the electricity grid. However, these sources lack the conventional reliability that fossil fuels, such as natural gas, and oil have previously provided. The solution lies in energy storage, and exactly why battery storage systems are the means for renewable energy sources to become truly transformative and revolutionize the energy market. In the first part of this paper, a comprehensive summary of the different types of energy storage technologies have been provided along with their features, which make each technology suitable for different applications. Next, a detailed chapter focused on battery storage systems and their properties is provided along with the ancillary services they offer as sustenance and support sources integrated in the electric grid. These service are integral to the continuous transmission of power to consumers, and necessary for the supply to meet end-user demands. Among these service include frequency regulation as well as spinning reserve services, the latter being important under emergency condition following a power disruption. Regulation services however, are constantly required for grid stability and reliability, which is why this service was selected for further market analysis. For this market analysis, the California Independent Systems Operator (CAISO), and PJM Interconnection (PJM) were selected as both have extensive regulation markets and two of the major power suppliers nationwide. The main question in conducting this analysis was to determine which market would be more attractive and profitable for a potential regulation provider to invest using a Lithium ion battery. The Regulation Market Clearing Price (RMCP) for each market was extracted from the operators’ annual reports over the last six years and used as measure of investor revenue. The Levelized Cost of Energy Storage was computed for a Lithium ion battery with certain characteristics, and the investor revenue was calculated as a percent of the LCOE. Our analysis showed that although CAISO’s regulation market is showing growth in the recent years, especially in 2016 during the period of increased regulation requirement, PJM has had consistently higher RMCP values, which means the investor revenue would be higher in PJM. Our calculations show that investing a Lithium ion battery with a power rating of 10MW, and energy capacity of 5 MWh, operating at 89% efficiency for 4.8 cycles per day for 350 days in PJM is going to be economically a much smarter choice.
M.S. In Electrical Engineering, May 2017
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Title: NOVEL AUTONOMOUS DRONE ARCHITECTURE WITH WIRELESS NETWORK USING REAL-TIME SIGNAL PROCESSING AND MOBILE DEVICE FOR ASSISTING RESCUE SERVICE
Creator: Kim, Heekyung
Date: 2015, 2015-12
Description: The Autonomous Drone can be economically one of the effective and efficient tools for disaster management. In this research, for disaster...
Show moreThe Autonomous Drone can be economically one of the effective and efficient tools for disaster management. In this research, for disaster relief operations, Autonomous Drone Architecture with wireless network provides disaster assistance by tracking a survivor and getting important information from multiple sensors on it. [1] ADWN architecture consist of two different platforms, Raspberry pi and Arduino, to separate their roles of the process, which are like collecting the sensor data and sending control signal from Raspberry Pi to Arduino. Once gathering data from sensors and transmitting it to Raspberry Pi, it can analysis by applying signal processing formula in real-time. [2] In this case, Raspberry Pi can multitask process and use various language libraries such as OpenCV, Python, and others. Also, Raspberry Pi can add lots of sensors, a camera, and other kinds of boards. Using these features, transmitted data can be processed in real-time and be sending to Arduino to control with reduced error. These strength of ADWN architecture provides scalability and high availability to control drone as a disaster assistance.
M.S. in Electrical Engineering, December 2015
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Title: POWDER CHARACTERIZATION AND PROCESS OPTIMIZATION FOR COLD COMPACTION AND SINTER APPLICATIONS OF COMMERCIALLY PURE TITANIUM POWDERS
Creator: Araci, Kerem
Date: 2011-08, 2011-07
Description: Near net shape manufacturing using powder metallurgy (P/M) technology and processes can significantly reduce material waste and cost during...
Show moreNear net shape manufacturing using powder metallurgy (P/M) technology and processes can significantly reduce material waste and cost during component fabrication. This study includes all the efforts to evaluate near net shape consolidation processes utilizing several different commercially pure titanium (CP-Ti) powders, focusing on the one produced by Armstrong Process® technology. Powder characteristics were studied in terms of morphology, particle size distribution, apparent and tap densities, and chemistry. Desired particle size distributions and higher powder densities were observed for HDH powders, while unique coral-like morphology was examined for the Armstrong Process® powder. Ball milling of the Armstrong Process® powder was systematically investigated by evaluating the impact on the particle size distribution, powder density and chemistry. Cold-uniaxial compaction of the milled powders was also evaluated in terms of theoretical density and green strength as a function of compaction pressure and lubrication techniques. Green densities were varied from 79 % to 91% for different powder compacts in different compaction conditions. Excellent green compaction of 145 MPa was approached by green compacts of Armstrong Process® powder. Sinter processing of the green compacts was investigated to approach relatively advanced tensile and flexural properties as a function of process temperature, time and heating rate. Near net-shape components which were fabricated by pressing and sintering were shown to achieve near-full densification with up to 97% of the theoretical density. Properties of P/M materials after the consolidation process were characterized and compared to those of conventionally produced materials.
M.S. in Materials Science and Engineering, July 2011
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Title: CLOSED-LOOP CONTROL GUST SUPPRESSION AT OF LIFT FOR LONGITUDINAL LOW REYNOLDS NUN4BERS
Creator: Kerstens, Wesley
Date: 2011-07-26, 2011-07
Description: Experiments are conducted to investigate the ability of variable pressure, pulsed-blowing actuators and zero-net-mass-flux actuators to...
Show moreExperiments are conducted to investigate the ability of variable pressure, pulsed-blowing actuators and zero-net-mass-flux actuators to maintain a constant lift force on a low aspect ratio, semi-circular wing in a longitudinally gusting flow. Dynamic models of the lift response to actuation and the lift response to longitudinal gusting are obtained through modern black-box system identification methods. Robust, H∞, closed-loop controllers are synthesized using a mixed sensitivity, loopshaping approach. An additional feed-forward disturbance compensator is designed based on a model of the unsteady aerodynamics. The controllers show suppression of lift fluctuations at low gust frequencies, f < 1Hz (reduced frequency, k < 0.09). At higher frequencies, the control performance degrades due to limitations related to the time for a disturbance, created by the actuators, to convect over the wing and establish the flow field that leads to enhanced lift on the wing. Similar limitations are observed for both wings even though the bandwidth of the zero-net-mass-flux actuators is an order of magnitude higher than that of the pulsed-blowing actuators.
M.S. in Mechanical and Aerospace Engineering, July 2011
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Title: MODELING, ANALYSIS AND DESIGN OF MULTI-CHANNEL BONDING FOR IEEE 802.11 WLANS
Creator: Khairy, Sami
Date: 2016, 2016-12
Description: The aim of this dissertation is to study the performance of distributed and opportunistic multi-channel bonding protocol in IEEE 802.11ac...
Show moreThe aim of this dissertation is to study the performance of distributed and opportunistic multi-channel bonding protocol in IEEE 802.11ac WLANs, and design channel bonding strategies to efficiently utilize the available spectrum. To this end, we first develop an analytical framework to study the throughput performance of WLANs with co-existing ac users and legacy users, characterizing the contentions among ac and legacy users in both primary and secondary channels. By modeling the transmissions of legacy users and ac users with and without bonding as a twolevel renewal process, the channel bonding probability of ac users in each secondary channel can be derived. Based on the bonding probability, MAC throughput of ac and legacy users can be analyzed respectively. Our analysis show that in a homogeneous multi-channel WLAN where only ac users are present, the contention probability of ac users is the same as that in a single channel with the same number of users; and in a heterogeneous WLAN with both ac and legacy users, an ac user can achieve a higher throughput than a legacy user, although the overall throughput decreases due to the increased contention level imposed by ac users in secondary channels. Based on the analysis, we further propose a channel selection strategy for ac users to select the best primary channel, in order to mitigate the contentions in the network and attain the maximal throughput. Analytical results show that primary channel selection is indifferent in a homogeneous network, whereas in a heterogeneous network, ac users should select the least congested channel as the primary channel to attain the maximal throughput. To evaluate the performance of a multi-channel WLAN, we develop an event-driven simulator based on network simulator-3 (NS-3). Extensive simulations validate our analyses and the efficiency of the proposed channel selection strategy.
M.S. in Electrical Engineering, December 2016
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Title: MITIGATING THE PAIN OF SOCIAL OSTRACISM THROUGH ACCEPTANCE
Creator: Zalizniak, Kevin C.
Date: 2012-05-09, 2012-05
Description: Social ostracism, the willful exclusion and ignoring of individuals, almost universally leads to feelings of decreased well-being and self...
Show moreSocial ostracism, the willful exclusion and ignoring of individuals, almost universally leads to feelings of decreased well-being and self-esteem through a neurobehavioral path similar to that responsible for physical pain (Eisenberger, Jarcho, Lieberman, Naliboff, 2006), negatively impacting overall life satisfaction (Zadro, Williams, and Richardson, 2004). This study aimed to compare the potential therapeutic benefits of acceptance based approaches, used in Acceptance and Commitment Therapy, to traditional control based approaches, such as thought blocking, in mitigating the pain of social ostracism. Participants were 111 college students. Each participant was randomly assigned to receive a brief acceptance, thought blocking, or visualization exercise before being socially ostracized through a computerized virtual ball toss paradigm. Subjective correlates of pain experience, including anger, general mood, belonging, control, self-esteem, and meaningful existence were assessed using a measure developed by Zadro, Williams, and Richardson (2004). Results revealed that participants who had received the acceptance exercise reported significantly more meaningful existence following social exclusion. Results are discussed in the context of previous research on social pain and meaningful existence (incorporating quality of life), as well as future research directions for finding strategies for mitigating the pain of social ostracism.
M.S. in Psychology, May 2012
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Title: RHEOLOGY OF ENTANGLED POLYMER LIQUIDS IN EQUIBIAXIAL ELONGATIONAL FLOWS
Creator: Mick, Rebecca M.
Date: 2015, 2015-05
Description: Equibiaxial deformation is an important flow in industrial processes such as film blowing and blow molding. Unfortunately, it is very...
Show moreEquibiaxial deformation is an important flow in industrial processes such as film blowing and blow molding. Unfortunately, it is very difficult to implement experimentally which has led to empirical design of these processes. A technique called continuous lubricated squeezing flow (CLSF) has been developed to perform equibiaxial deformation on systems such as polymer melts. This technique is used in this study to measure the behavior of entangled polymer melts in equibiaxial elongation to further the understanding of these materials in industrially relevant flows. The results of CLSF experiments on three linear chain polymer systems show strain softening for strain rates resulting in Weissenberg numbers, Wi = ε˙Bτd > 1. Higher rates lead to greater softening. The deviation from the linear viscoelastic (LVE) prediction occurs at about a strain of one for all the materials. Equibiaxial and shear behavior were compared for two monodisperse linear systems. When normalized by LVE behavior, the two flows yield similar behavior such that the equibiaxial rheology could be inferred from shear rheology. Unfortunately, polydisperse linear and branched systems did not show the same behavior. The two monodispere systems were compared to the GLaMM and Discrete Slip-Link molecular theories. Neither model could successfully predict the equibiaxial behavior; both predicted excessive strain softening and a premature deviation from LVE. Recent literature has suggested that based on uniaxial measurements, dilution changes the behavior of an entangled polymer system. This is contrary to theories of polymer dynamics. A pure melt and diluted melt with the same entanglement density were compared in shear and equibiaxial flows after adjusting for changes in friction. The results were consistent with universality principles of entangled polymers; the uniaxial results require further investigation.
Ph.D. in Chemical Engineering, May 2015
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Title: THE IMPACT OF TRUST ON LEADER EMPOWERING BEHAVIOR
Creator: Sternburgh, Angela M.
Date: 2011-04-22, 2011-05
Description: This study examined the relationship between trust and leader empowering behaviors across 250 matched pairs of leaders and employees in a...
Show moreThis study examined the relationship between trust and leader empowering behaviors across 250 matched pairs of leaders and employees in a Fortune 500 Midwestern U.S. company. The relationships between propensity to trust, trustworthiness, trust, a meta-perception of trust, and leader empowering behavior were examined. The goal of this study was to test the mediating role of trust and/or the metaperception of trust on the relationship between trustworthiness and leader empowering behavior. This study obtained both leader and employee ratings, which permitted the examination of both single source and multi source data. Results supported a partial mediation effect indicating that trust and the meta-perception of trust partially mediated the relationship between trustworthiness and leader empowering behavior. This study is important because previous research has predominantly focused on examining employee perceptions of trust, this was the first study to explore the meta-perception of trust, and this study transferred measures of leader empowering behaviors to more behaviorally based statements. Implications of this study are explored.
Ph.D. in Psychology, May 2011
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