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Title: DEVELOPMENT OF ACTIVE RESPONSE TECHNOLOGY FOR SAFETY APPLICATIONS IN POWER SAWS
Creator: Assaliyski, Marin I.
Date: 2014, 2014-05
Description: This thesis presents a study of kickback occurrences on table saws, as well as the development and evaluation of a system designed to mitigate...
Show moreThis thesis presents a study of kickback occurrences on table saws, as well as the development and evaluation of a system designed to mitigate health and property hazards due to kickbacks. A kickback is an unwanted situation during the cutting process of many powered circular saw tools, during which the operator of the tool loses control, potentially resulting in severe property and bodily harm. Multiple safety devises exist to prevent this type of situation from occurring; however, all of these devices are passive and often become a burden by decreasing e ciency, and are therefore often removed by the users. This thesis seeks to study the occurrence of kickbacks and to present an active electronic detection system that is able to aid in mitigation of potential damage to property or persons by developing responsive, robust, and practical methods of kickback detection. Implemented detection methods are presented and evaluated for performance. Concepts are also developed, presented, and discussed with the purpose of generating topics for future work. An experimental brake is used to evaluate the performance of the detection methods with an integrated system.
M.S. in Mechanical and Aerospace Engineering, May 2014
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Title: SELF-POWERED DC SOLID STATE CRICUIT BREAKERS
Creator: Miao, Zhenyu
Date: 2015, 2015-07
Description: Dc power systems are better system solutions than ac power systems in application areas such as data centers, electric ships and dc micro...
Show moreDc power systems are better system solutions than ac power systems in application areas such as data centers, electric ships and dc micro-grids. But the lack of fast and cost effective dc circuit breakers impedes the development and application of dc power systems. This thesis introduces a new type of self-powered dc solid state circuit breakers (SSCB) which are inactive during normal operation but can be triggered and powered up by a short circuit event. The design of a unidirectional solid state circuit breaker and a bidirectional solid state breaker are proposed. The solid state circuit breakers are consisted of normally-on SiC JFETs as main power switches and gate drivers featuring fast start-up forward-flyback converters. The operation principles of the circuit breakers are analyzed in details. Prototypes are built and verified in short circuit tests. The circuit breaker prototypes can interrupt short circuit currents up to 180 amperes at a dc bus voltage of 400 volts within 1 microsecond. Chapter 1 introduces the safety considerations of dc power systems, characteristics of conventional ac circuit breakers, and the development of solid state circuit breakers. Chapter 2 introduces the concepts of the proposed self-powered SSCBs and operation principle of a fast start-up forward-flyback converter. Chapter 3 introduces the schematic design of a unidirectional self-powered SSCB, its operation principle and experimental results. Chapter 4 introduces the schematic design of a bidirectional self-powered SSCB, its operation principle and experimental results. Chapter 5 concludes the thesis and looks forward to future work.
M.S. in Electrical Engineering, July 2015
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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: INTENTION AND ACTION: THE THEORY OF PLANNED BEHAVIOR AND EFFECT OF HABIT AND MINDFULNESS ON INFLUENZA VACCINATION
Creator: Mattson, Melissa
Date: 2013, 2013-07
Description: Several models of health behavior have been utilized in attempting to understand vaccination behavior, with mixed success. Additionally, there...
Show moreSeveral models of health behavior have been utilized in attempting to understand vaccination behavior, with mixed success. Additionally, there is a dearth of research on vaccination behavior in young, healthy adults, who are among the primary transmitters of preventable illness. The present study examined the applicability of the Theory of Planned Behavior (TPB) and the effects of past behavior and other health habits on vaccination intentions and influenza vaccine uptake. It also examined the moderating effects of mindfulness on the intention-behavior relationship for influenza vaccination. A total of 244 participants completed measures assessing attitudes, subjective norms, perceived behavioral control (PBC), and vaccination intentions in the TPB; the Self-Report Habit Index for three health behavior habits; and the Mindful Attention Awareness Scale. Participants also completed a follow-up assessment regarding vaccine uptake at the end of the 2012/2013 influenza season. Results indicated that attitudes and subjective norms explained >57% of the variance in vaccination intentions, with subjective norms predicting the largest portion of the variance in intention to receive the vaccine, as hypothesized. Intentions mediated the relationship between attitudes and vaccination, and between subjective norms and vaccination. Intentions and past vaccination predicted vaccination during the 2012/2013 influenza season, although PBC and other health behavior habits did not. Finally, mindfulness did not moderate the intention-behavior relationship for influenza vaccination. These findings provide evidence for the utility of the TPB in explaining vaccination intentions and behavior, as well as for the role that past behavior may play in predicting future vaccination.
PH.D in Psychology, July 2013
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Title: APPLICATION OF BIMOLECULAR FLUORESCENCE COMPLEMENTATION ASSAY FOR MONITORING BCL-2 AND BAX INTERACTION
Creator: Chayanam, Sudharani
Date: 2011-07, 2011-07
Description: Bimolecular Fluorescence Complementation is a modern method to monitor protein-protein interactions in live cells. The objective of this...
Show moreBimolecular Fluorescence Complementation is a modern method to monitor protein-protein interactions in live cells. The objective of this project is to employ this method for deciphering signaling complexes involved in androgen receptor mediated cell death. Bcl-2 and Bax were selected to serve as initial experimental targets since these proteins were known to interact with each other. In this method, split EGFP consisting of 1-157 amino acid N-terminal fragment was fused to Bcl-2 and 158-238 amino acid Cterminal fragment to that of Bax with a six amino acid linker (SGSGVD) to generate fusion expression cassettes. We tested two combinations of fusion expression cassette pairs NGFP/Bcl-2, Bax/CGFP and NGFP/Bcl-2, CGFP/Bax for a BiFC signal by cotransfecting them in Human Embryonic Kidney 293T cells. Our results show that fusion proteins NGFP/Bcl-2, Bax/CGFP and CGFP/Bax were well expressed as evident by the Western blots. But the efficiency of BiFC formation was better for NGFP/Bcl-2 and CGFP/Bax fusion proteins combination than NGFP/Bcl-2 and Bax/CGFP fusion proteins. Therefore indicate that the fluorescence complex formation imparting the BiFC signal is specific for Bcl-2 and Bax interaction. Though the BiFC signal obtained was brighter for image capturing but the efficiency was very low, only few fluorescing cells were detected under the fluorescence microscope. Despite this weakness, BiFC is still a promising technique for studying protein-protein interactions in living cells and at single cell level.
M.S. in Biology, July 2011
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Title: DEVELOPMENT OF MULTI-NOZZLE MICRO-EXTRUDER FOR LAYERED MANUFACTURING OF MULTI-MATERIAL ENERGY STORAGE DEVICES
Creator: Mohamed Ayub, Shaik Mohamed Imran
Date: 2014, 2014-05
Description: Additive Manufacturing is critical in the development of high energy density storage devices for its flexibility to manufacture complex parts...
Show moreAdditive Manufacturing is critical in the development of high energy density storage devices for its flexibility to manufacture complex parts with different discrete compositions like cathodes, anodes and electrolytes. Such storage devices under sub- millimeter scale with micro-structured interdigitated layout could significantly improve its power and energy density. Over the past few years, scientific communities in Rapid Prototyping technology have been mainly focusing on various methods of Modeling and representing Multi-Material Object under single CAD data structure which would enable post processing and rapid prototyping of Multi-Material Object (MMO). This thesis will address the processes involved in the development of Multi-Material Micro Extrusion (M3E) device for manufacturing high density energy storage devices through discrete composition control in Solid Freeform Fabrication (SFF). The primary goal of the research is to develop a rectilinear motion platform with a multi-extrusion system and an open loop control interface to regulate the unreliable extrusion of slurries of different discrete composition. The dissertation will also address the software methodology to discretize 3D-CAD models to represent multiple material composition followed by slicing it into 2.5D layers, which will enable to create Computer Numeric Control (CNC) path program. The scope of this research is further extended to study and optimize various mechanical process inputs with respect to extrusion output parameters.
M.S. in Mechanical and Aerospace Engineering, May 2014
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Title: MICROGRID OPERATION, CONTROL AND PROTECTION AT lIT
Creator: Che, Liang
Date: 2013, 2013-07
Description: Distributed Energy Resource (DER) which includes distributed generation (DG), distributed storage system, and adjustable loads is a key...
Show moreDistributed Energy Resource (DER) which includes distributed generation (DG), distributed storage system, and adjustable loads is a key component in microgrid operations. Microgrids could be clustered at distribution levels to enhance the economics and the reliability of small DGs such as microturbines and wind generation turbines as well as DGs with power electronic interfaces such as photovoltaic (PV) arrays and fuel cells. Microgrid is a small electric power system integrated with on-site DERs to serve all or some portion of the local load which is connected to the utility grid through the point of common coupling (PCC). Microgrids can operate in both grid-connected mode and island mode. The structure and components of hierarchical control for a microgrid at Illinois Institute of Technology (IIT) are discussed and analyzed. Case studies would address the reliable and economic operation of IIT microgrid. The simulation results of IIT microgrid operation demonstrate that the hierarchical control and the coordination strategy of distributed energy resources (DERs) is an effective way of optimizing the economic operation and the reliability of microgrids. The protection is one of the crucial challenges of microgrid operation. Traditional protection schemes for radial distribution networks will not work successfully in microgrids without much modification. The protection scheme of IIT microgrid is discussed. Based on the fault current contributed by synchronous generators in island mode, the IIT microgrid adopts a localized differential protection scheme with adaptive xiv relay settings which feature a multi-level backup protection strategy. The proposed protection scheme would utilize the looped structure of IIT microgrid for enhancing the reliability of microgrid operation. The simulation results of IIT microgrid protection show the effectiveness of the proposed protection scheme.
M.S. in Electrical Engineering, July 2013
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Title: OPTIMAL LOAD SCHEDULING IN COMMERCIAL AND RESIDENTIAL MICROGRIDS
Creator: Ganji Tanha, Mohammad Mahdi
Date: 2015, 2015-05
Description: Residential and commercial electricity customers use more than two third of the total energy consumed in the United States, representing a...
Show moreResidential and commercial electricity customers use more than two third of the total energy consumed in the United States, representing a significant resource of demand response. Price-based demand response, which is in response to changes in electricity prices, represents the adjustments in load through optimal load scheduling (OLS). In this study, an efficient model for OLS is developed for residential and commercial microgrids which include aggregated loads in single-units and communal loads. Single unit loads which include fixed, adjustable and shiftable loads are controllable by the unit occupants. Communal loads which include pool pumps, elevators and central heating/cooling systems are shared among the units. In order to optimally schedule residential and commercial loads, a community-based optimal load scheduling (CBOLS) is proposed in this thesis. The CBOLS schedule considers hourly market prices, occupants’ comfort level, and microgrid operation constraints. The CBOLS’ objective in residential and commercial microgrids is the constrained minimization of the total cost of supplying the aggregator load, defined as the microgrid load minus the microgrid generation. This problem is represented by a large-scale mixed-integer optimization for supplying singleunit and communal loads. The Lagrangian relaxation methodology is used to relax the linking communal load constraint and decompose the independent single-unit functions into subproblems which can be solved in parallel. The optimal solution is acceptable if the aggregator load limit and the duality gap are within the bounds. If any of the proposed criteria is not satisfied, the Lagrangian multiplier will be updated and a new optimal load schedule will be regenerated until both constraints are satisfied. The proposed method is applied to several case studies and the results are presented for the Galvin Center load on the 16th floor of the IIT Tower in Chicago.
Ph.D. in Electrical and Computer Engineering, May 2015
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Title: YIELD BEHAVIOR OF SOLID FOAMS UNDER MULTIAXIAL STATES OF STRESS
Creator: Ehaab, Mohammad
Date: 2011-12-14, 2011-12
Description: Growing use of solid foams as core material in load bearing composite sandwich structures requires the development as well as validation of...
Show moreGrowing use of solid foams as core material in load bearing composite sandwich structures requires the development as well as validation of predictive yield criteria for these extremely porous and, hence, lightweight engineering materials. It has been well established that solid foams, unlike the majority of bulk materials, have a pressure dependent yield behavior. This makes the validation of various yield criteria proposed in literature a challenging task because of the need for complex biaxial and triaxial experiments, which is the main reason for both the scarcity of data and the lack of predictive power in existing models. Although there have been a limited number of studies recently in literature to generate data beyond uniaxial compression and tension experiments by introducing new loading apparatuses such as Arcan apparatus and universal biaxial testing device (UBTD), they have been limited to probe shear-compression and shear-tension states of stresses without independent control of the shear component. Therefore, the data extracted from these experiments cover only a small fraction of stress space. An example of a truly biaxial testing machine with independent load control is biaxial crushing machine (BICURMA) which, however, is restricted to only compressive loads. One must recognize that biaxial testing, even with full tension/compression control, doesn’t expand the fraction of yield surface that can be probed in any significant proportion beyond shear/compression techniques. Extremely pressure dependent mechanical behavior of solid foams requires triaxial experiments for a full description of their yield surface, hence the challenge. This work addresses this challenge by using a multiaxial testing apparatus (MATA) developed at IIT to comprehensively probe the yield surface of Divinycell H100 and H130 PVC foams through uniaxial, biaxial and triaxial experiments where loads are independently controlled in each orthogonal direction. Data reduction relies on new scalar measures of characteristic stress and strain proposed by Ayyagari and Vural (2011), and yield data is compared with their newly developed pressure dependent yield criterion. Experimental results reveal that solid foams exhibit both quadratic and linear pressure dependence. Although quadratic dependence on pressure has been previously shown in literature with a limited number of experimental yield data, extensive yield data of the current study suggests a significant linear dependence as well. The final portion of this study outlines a set of new micro-scale experiments designed to test mechanical behavior of individual ligaments that make up Duocell aluminum foam, and some preliminary results.
M.S. in Mechanical, Materials, and Aerospace Engineering, December 2011
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Title: ART ECO, CHONGMING ISLAND, CHINA
Creator: Thadhani, Monika
Date: 2011-04-26, 2011-05
Description: Architecture has always been the result of the delicate balance between art and science & form and function. This thesis project simply...
Show moreArchitecture has always been the result of the delicate balance between art and science & form and function. This thesis project simply embraces this belief by creating a museum and its distinctive form collectively with its sustainable design and environmentally conscious program and operation. Art Eco Museum is an element of prospective sustainable city development on Chongming Island in China. The Museum site is located near Shanghai metropolitan area at the Yangtze River outlet by the East Sea. The Island is an escape from the urban dynamic lifestyle of one of the world's most populated city - Shanghai. Chongming Island is a sanctuary that has 1200 square kilometers of undeveloped land with wildlife, wetlands, agriculture and forest preserves. The Art Eco Museum and its site, designed with a consideration of existing environment and Asian culture, becomes an innovative local and global approach and a model for future energy efficient projects while showcasing Chinese and international art. The museum program creates a culture of sustainability, employing all potential sustainable features to minimize energy use and utilize natural resources in its design and operation. The proposed project is not only a sustainable solution for the museum design but is also an example of the architecture which expression emerges from nature in its symbolic implication, form and function. The use of its organic architectural form insinuates the symbolic object of China - bamboo, and its economic and cultural significance. Bamboo, as a symbol of long life in China, became an inspiration for the project design, with its form and meaning. The Art Eco Museum floor plan layout was arranged according to Bamboo Chinese painting composition. Focusing on design that have lead to positive approaches towards a sustainable future, the exhibition at Art Eco Museum takes a step towards making these ideas a reality for consumers and designers in the current ethical and environmental awareness. The idea of sustainability combines the intelligent use of renewable resources with forward-thinking solutions. Most importantly, museum exhibitions place emphasis on the involvement of the consumer, giving them the tools and the knowledge necessary to understand the general concept of sustainability and its application to everyday life. The Art Eco Museum project is an example of aesthetically beautiful art form which serves functional purpose of science to remodel the world and peoples lifestyle to make it more perfect for human habitation.
M.S. in Architecture, May 2011
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Title: SMALL MODULAR NUCLEAR REACTORS: LEARNING AND PRODUCTION
Creator: Kotlyarevsky, Arnold
Date: 2013, 2013-07
Description: Small Modular Nuclear Reactors o er a new alternative to carbon based energy sources in the energy market of the near future. Understanding...
Show moreSmall Modular Nuclear Reactors o er a new alternative to carbon based energy sources in the energy market of the near future. Understanding the economic forces driving the industrial manufacturing process is crucial to determining the viability of SMRs. This study is a continuation of research that developed a parametric model and initial production cost estimates for a generic 100MWe SMR integrated reactor vessel. The primary goal of this study was to characterize the learning rates, lot sizes, and optimum production of SMR IRVs using the parametric model and the initial cost estimates. Three separate models were developed based on increasing levels of learning transfer: no learning transfer, partial learning transfer, and full learning transfer. Models with no learning transfer and full learning transfer bounded the values for the learning curve expected for IRV manufacture. A model with a partial transfer of learning yielded production cost estimates of $312.2 million. Production of an SMR IRV based on this model is expected to see a learning rate 95.5%. Using the information from the other two models, the expected learning rate for IRV production is expected to fall between 93.3% and 99.1% Simulations of lot sizes of 1 to 12 were conducted to determine the manufacturing lot size that optimizes the factory setting. An optimum con guration of 5 units per lot was determined to be the minimum. However, the lot size is recommended to be increased to 6 units to withstand the possibility of cancellation. In this con guration, the average unit cost is $262 million, with a learning rate of 98.1%. Another important result indicates that optimum manufacturing outcomes are not necessarily correlated with higher levels of learning. Production in larger lot sizes is bene cial, especially for components that are few in number, like the pressure vessel.
M.S. in Physics, July 2013
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Title: COGNITIVE DEVELOPMENTAL LEVEL AS A MODERATOR OF LANGUAGE SKILLS AND SOCIAL SKILLS AS WELL AS ACADEMIC ACHIEVEMENT AND SOCIAL SKILLS
Creator: Reife, Ilana
Date: 2012-11-13, 2012-12
Description: Past research has provided evidence that social skills are correlated to both academic achievement and language skills. In addition, Piaget’s...
Show morePast research has provided evidence that social skills are correlated to both academic achievement and language skills. In addition, Piaget’s theory asserts that certain cognitive abilities develop independent of learning (both language and academic skills) that occurs in school. The present study examined the impact of cognitive developmental level as a moderator for the relationship between social skills and academic achievement. Cognitive developmental level was measured using conservation tasks. Social skills were measured with the Social Skills Inventory System. Academic achievement was measured by the Woodcock-Johnson Tests of Achievement, Third Edition, Normative Update. This study also assessed cognitive developmental level as a moderator between social skills and language skills. Language skills were measured with the Peabody Picture Vocabulary Test. A hierarchical linear regression yielded results indicating that when controlling for IQ, gender and ethnicity, cognitive developmental level did not moderate relationships between social skills and language and social skills and academic achievement. However, post hoc analyses demonstrated that ethnicity provides a significant amount of the variance and acts as a covariate. This study contributes to the literature by providing evidence that ethnicity significantly impacts teacher ratings of social skills.
M.S. in Psychology, December 2012
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Title: MECHANICAL AND BIOCHEMICAL FACTORS INFLUENCING INITIAL PLATELET ADHESION TO COLLAGEN: IMPORTANT ROLE FOR SLIDING AND ROLLING IN ACCELERATED AGGREGATE FORMATION
Creator: Au, Bonnie
Date: 2015, 2015-05
Description: Injury at the vessel wall leads to exposure of collagen to which platelets initially adhere, grow into aggregates and eventually thrombotic...
Show moreInjury at the vessel wall leads to exposure of collagen to which platelets initially adhere, grow into aggregates and eventually thrombotic masses which can occlude the vessel lumen. This process underlies the disorders of heart attack and stroke. The initial phase of platelet aggregation governs the extent of thrombus formation. We have investigated initial platelet attachment to collagen-coated surfaces under mechanical and biochemical conditions in a parallel plate flow reactor. A simple algorithm has been developed to simulate the effects of platelet sliding/rolling on the surface with respect to the development of surface aggregate formation. Platelets are hypothesized to stop such movement once they collide with a neighboring platelet in their pathway (due to platelet coherence that strengthens the overall adhesive forces due to platelet-platelet bonding). We and others have observed microscopically that platelets will either attach firmly onto the surface, roll and slide or detach completely from the surface. Platelet behavior was investigated for overall adhesion and the translocation dynamics on overall adhesion on temperature, flow conditions, C-reactive protein (CRP), and coffee consumption. Our findings indicate that temperature, shear force, and CRP promote platelet adhesion and the intake of coffee impedes platelet adhesion.
M.S. in Biomedical Engineering, May 2015
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Title: DISTRIBUTION OF CRP/FNR FAMILY TRANSCRIPTION FACTORS IN SELECT BACTERIAL GENOMES
Creator: Yang, Shengning
Date: 2012-05-07, 2012-05
Description: Cyclic adenosine monophosphate (cAMP, cyclic AMP or 3'-5'-cyclic adenosine monophosphate) receptor protein (abbreviated as CRP), also known as...
Show moreCyclic adenosine monophosphate (cAMP, cyclic AMP or 3'-5'-cyclic adenosine monophosphate) receptor protein (abbreviated as CRP), also known as catabolite gene activator protein, is one type of regulatory protein in bacteria. It acts as a secondary messenger in many intracellular pathways, especially the signal transduction by binding cAMP, which allows the protein to bind DNA sequence in the promoters. Fumarate/nitrate reduction transcriptional regulator, in short Fnr, is another signal transduction molecule which transfers from oxygen status to nifL (Nitrogen fixing bacteria L) protein. Both Crp and Fnr can be grouped into a Crp-Fnr family of transcription factors in many bacteria strains. In this study, we identified Crp-Fnr family genes from different bacteria genomes. Using the Crp-Fnr gene sequences we reconstructed phylogenetic trees for 250 select bacterial genomes which contains at least one Crp-Fnr family gene. We also selected representative Escherichia coli and Salmonella enteriaca genomes for phylogenetic analysis. The circular maps for the four select bacterial genus, Listeria, Salmonella, Escherichia and Brucella were created to demonstrate the genomic locations of Crp-Fnr family genes. Our results showed that the location of Crp-Fnr family transcription factor genes are syntenic amongdifferent bacteria bacterial genomes, indicating their early ancestry acquisition prior to the speciation events.
M.S. in Biology, May 2012
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Title: SILICON CARBIDE JFET BASED SOLID STATE CIRCUIT BREAKERS FOR MEDIUM VOLTAGE DC SYSTEMS
Creator: Moradkhani Roshandeh, Aref
Date: 2016, 2016-07
Description: In application areas such as data centers, electric ships and dc microgrids, dc systems are better systems than ac counterparts, however lack...
Show moreIn application areas such as data centers, electric ships and dc microgrids, dc systems are better systems than ac counterparts, however lack of a fast, reliable and cost effective dc circuit breaker is a big obstacle on the way of development and wide usage of these kind of systems. Nowadays since the demand for electric power and especially, access to renewable energy sources such as solar thermal generation which are located in deserts and off-shore wind power, continuously increases the demand and interest in High Voltage Direct Current (HVDC) and Medium Voltage Direct Current (MVDC) systems. In order to accept and rely on such systems, availability of fast and robust circuit breakers is inevitable which makes them one of the key enabling technologies. This thesis introduces a novel design for solid state circuit breakers (SSCB) for MVDC systems. This SSCB is inactive during normal operation and when a fault occurs, by getting power from the fault condition will be triggered on and clear the fault. This SSCB is consisted of a fast startup flyback-forward converter as a gate driver and two normally-on SiC JFETs as the main static switches which share the bus voltage equally during the fault condition. The operation principles of the SSCB are explained and analyzed in details. Moreover, prototypes are built and tested in short circuit tests. As observed in real test and experiments, the circuit breaker prototype can interrupt short circuit fault current up to 150 amperes at a dc bus voltage of 1000 volts within 3 microsecond.
M.S. in Electrical Engineering, July 2016
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Title: Textile Openings
Creator: Carvallo, Maria Paulina
Date: 2011-12-06, 2011-12
Description: A facade may serve many functions throughout the life of a building, but the primary purpose of a building’s facade is to protect the interior...
Show moreA facade may serve many functions throughout the life of a building, but the primary purpose of a building’s facade is to protect the interior of a structure from the outside environment. By examining an element of every facade design, its openings, one may also find solutions to other design and layout questions concerning a building’s interior. Textile facades show potential as new and interesting materials for facade design. However, textile facades must reinvent or adapt standard facade elements such as windows, doors, and other openings within the constraints of the material properties exhibited by textiles. This thesis explores potential facade opening mechanisms, including technical and natural examples. Details of textile facades are considered, including laser cutting of polyester fabrics, textile material properties and tension deformation, and a variety of textile facade designs. Furthermore, a standardized design workflow and process for considering multiple environmental variables present in and around facades, such as solar thermal, day lighting, ventilation, and identity, are discussed and illustrate that the methodology applied herein can be used to predict other applications of textiles.
M.S. in Architecture, December 2011
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Title: ENERGY SAVINGS FOR UAV FLIGHT IN UNSTEADY GUSTING CONDITIONS THROUGH TRAJECTORY OPTIMIZATION
Creator: Grimaud, Lou
Date: 2014, 2014-07
Description: The purpose of this thesis is to show how micro unmanned aerial vehicles can extract energy from periodic wind gusts and how this energy...
Show moreThe purpose of this thesis is to show how micro unmanned aerial vehicles can extract energy from periodic wind gusts and how this energy extraction is a ected by the e ects of unsteady aerodynamics and the spatial structure of the gust component. The trajectory of a small UAV ying through wind gusts is simulated with a two degree of freedom model. The non-dimensional model is set to include vertical and horizontal gusts of varying amplitudes and durations. From this model an optimization routine is performed in order to obtain the minimum gust amplitude needed to obtain a neutral energy trajectory. With these results, it is shown that neutral energy ight is possible through gusts speeds of only 10 to 30% of the ying speed of the aircraft. Analysis of the results shows that the lift coe cient has to be changed very rapidly in order to perform these maneuvers in short duration gusts. Moreover high lift values are often required. To achieve this kind of rapid change in the lift and drag forces, fast variations of the angle of attack are needed. The high lift values also require high angles of attack that are likely to cause separation of the ow over the airfoil. These fast variations at high angle of attack are shown to cause unsteady non linear aerodynamic responses. Traditional CFD simulations are far too computationally expensive to be implemented into the optimization routine. To solve this issue a low order model based on a paper by Goman and Khrabrov [7] (GK) is developed and validated against experimental results. This model produces accurate predictions of the lift and drag coe cients for a wide range of angles of attack and for di erent type of pitch inputs. With this GK model the in uences of the unsteady aerodynamics on the energy extraction problem are highlighted. The main di erence with quasi-steady aerodynamics model was found to be for gusts at a reduced frequency (k = cf u ) higher than 0.07. Around these values the potential performance is improved by introducing the unsteady model. The trajectories obtained include more violent changes in angle of attack in order to take full advantage of the unsteady e ects.
M.S. in Mechanical, Materials, and Aerospace Engineering, July 2014
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Title: NEW SUSTAINABLE CITY IN MACEDONIA
Creator: Dubrovski, Filip
Date: 2012-11-14, 2012-12
Description: Blessed with the unique power of limited understanding, for centuries human supremacy stood as the universal rule for success and progress....
Show moreBlessed with the unique power of limited understanding, for centuries human supremacy stood as the universal rule for success and progress. With this organized human dominance, present humankind challenged the once unapproachable frontiers of the planet climate equilibrium. For some it is Mother Nature’s perpetual behavior, for others the point of self-destruction. With only a minimum effort given to understand its power and relevance, the human ignorance continued to consume the values of commodity and comfort to achieve an illusion of happiness and self-achievement. Until about five years ago, this illusion created the world’s greatest financial crisis that until today still has no resolution. Addressing the present environmental, social and economic issues by designing a sustainable city becomes a daunting challenge. Given the global unfavorable urban conditions, it is somewhat difficult to understand how the city, man greatest achievement, can also be comprehended as a redemption. Nevertheless, the only certainty of the evolution pattern of civilization is that global population increases will additionally worsens these conditions. Unlike in the past centuries when population increases favored the rich and well established, these patterns now occur in rural regions of undeveloped societies that begin to grow swiftly but without the infrastructure to meet the demand. Additionally disadvantaging are the patterns of intensive sprawl of the mega metropolis which are now captives of the amplifying cost of energy and the congestion of transportation. Therefore, it is an imperative to visualize the New City with its predetermined scale as the most efficient sustainable smart tool to mitigate the xi consequences of these undesirable patterns that are causing social and environmental destruction. The project for a New Sustainable City in Macedonia is an approach that envisions multidisciplinary contributions to society, environment and the economy. Its purpose is to present the best example of a new civilized relation between natural and artificial environment. The design implements values of the walkable and community based transportation methods, multiple socially interactive public squares and elevated residence living. It aims to protect the natural environment and mitigate ecological threats due to climate changes.
M.S. in Architecture, December 2012
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Title: PROTOTYPE OF SUSTAINABLE NEW CITY IN CHILE
Creator: Hernandez Gomez, Soledad Macarena
Date: 2012-11-20, 2012-12
Description: In an era of global climate change and rapid urbanization, it is necessary to change the way of cities have been developed. Cities need a new...
Show moreIn an era of global climate change and rapid urbanization, it is necessary to change the way of cities have been developed. Cities need a new vision and a new strategy to reduce their impact on the environment. Therefore, it is essential to research about how to design sustainable cities, which are the main characteristics of a sustainable urban design, and how it is possible to combine all these factors in a sustainable way to develop a city which reduces impact in the ecosystem and creates a better quality of life as a place to live. For these reasons, one of the main objectives of this thesis is to develop a prototype of a sustainable new city based on the sustainable city principles, and also to understand the social, economic and environmental context where the city is located. In this proposal, the new city is located in the extreme South of Chile to replace a previous city that was destroyed by a volcanic eruption. Therefore, this new city - New Chaiten- is an opportunity in the region to build a city which represents a new vision of sustainable urban development which promotes a balance between the social and economic needs of the community and environmental conservation. Furthermore, it creates an enjoyable urban environment with a high quality of life while reducing energy consumption.
M.S. in Architecture, December 2012
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Title: MODELING AND PERFORMANCE ANALYSIS OF DISTRIBUTED COMPUTER NETWORKS WITH DIFFERENTIATED SERVICES
Creator: Monsef, Ehsan
Date: 2015, 2015-07
Description: The rapid growth of data usage in wired and wireless networks has witnessed an increase in diversity of user tra c in the last few decades. A...
Show moreThe rapid growth of data usage in wired and wireless networks has witnessed an increase in diversity of user tra c in the last few decades. A network with di eren- tiated services guarantees the provision of Quality of service(QoS) for di erent tra c classes by incorporating various class-based scheduling disciplines. Recently, there has been interest in the study of network performance modeling in networks with di erentiated services. In particular, the performance modeling of di erentiated ser- vice networks in distributed architectures has attracted several network communities. The heterogeneity of user tra c can have major impact on the overall performance of resource allocation problems in computer networks. This work aims at shedding light on the performance modeling of distributed wired and wireless environments with di erentiated services. We study the performance of priority-based distributed schemes for several important network applications: (i) network routing(load balanc- ing) in wired network (ii) network selection in wireless environment (iii) scheduling in Body Area Networks and (vi) Interference mitigation scheme for Wireless Body Area Networks. We will utilize Game-theoretic models to model the interaction between network entities and evaluate the system performance analytically and empirically. Our main objective is to investigate the degree in which various service di erentiation mechanisms have impact on the overall performance of distributed networks. We an- alyze several important equilibria properties such as existence, convergence time, and ine ciency for the studied network scenarios. Extensive simulations are conducted to empirically evaluate our game-theoretic analysis for di erent network applications. First, we study a network of parallel links where each link incorporates General Processor Sharing scheduling mechanism. Using the non-cooperative game model, we investigate the existence and uniqueness of equilibrium points. We study the e ciency of equilibria by deriving an upper bound on the Price of Anarchy (PoA). Finally, we utilize the simulation to compare our PoA bound with actual bound. Second, we study wireless network selection in a distributed environment with Discriminatory Processor Sharing (DPS) scheduling discipline. We consider a set of wireless clients in a network composed of multiple base stations with di erentiated services. The goal of each wireless client is to assign itself to a wireless base station that gives the higher throughput. We formulate the interaction between clients as a weighted congestion game and investigate the existence of equilibria. We show that the equilibrium does not necessarily exists for a general network model. We give several regimes under which the equilibrium is guaranteed to exist. These regimes are implemented either on the base stations or wireless clients. Furthermore, we derive several upper bounds on the equilibrium convergence time and give an extensive simulation to evaluate our results. Third, we consider the interaction between autonomous Wireless Body Area Networks(WBAN) in a crowded environment such as hospital. We propose a dis- tributed approach that mitigates the inter-WBAN interference using the game theory models. The interaction between WBANs is modeled as an in nite repeated game. We propose a "grim" strategy for the formulated game and prove the SPE property under speci c conditions. Furthermore, we investigate the equilibrium by comparing that to a sub-optimal Pareto strategy. We test our results using a speci c simulator designed for WBAN. Finally, we propose a new QoS framework for WBAN architecture. The goal of this framework is to implement a separate QoS layer in the design of WBAN stack protocol so that it becomes independent of the application layer. The framework o ers an application pro le interface where each application can submit its QoS require- ments. The implementation of QoS framework in a separate layer and independent of application layer enables more scalable WBAN application development.
Ph.D. in Computer Engineering, July 2015
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