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Articles 1 - 30 of 88
Full-Text Articles in Engineering
Voltage Stability Indices Based On Active Power Transfer Using Synchronized Phasor Measurements, Rui Sun
Voltage Stability Indices Based On Active Power Transfer Using Synchronized Phasor Measurements, Rui Sun
All Theses
In recent years and in the foreseeable future, power demands generally around the world and particularly in North America will experience rapid increases due to the increase of customers' requirements, while the development of transmission systems in North America is rather slow. Voltage stability assessment becomes one of the highest priorities to power utilities in North America. Voltage stability index is a feature for solving voltage stability problems. It is generated from the basic power flow equations and/or energy functions. The mathematical expression of a VSI is often written as a polynomial containing the systems real-time measurements such as voltage …
Linguistic Analysis Of Natural Language Engineering Requirements, Carl Lamar
Linguistic Analysis Of Natural Language Engineering Requirements, Carl Lamar
All Theses
In engineering design, the needs of the customer are expressed through engineering requirement statements. These requirement statements are often expressed using natural language because they are easily created and read. However, there are several problems associated with natural language requirements including but not limited to ambiguity, incompleteness, understandability, testability and over specificity. Several representation and analysis tools have been proposed to address these problems within a requirement statement. These tools include formal languages, such as UML and SysML, requirement management tools, such as IBM Telelogic Doors, and natural language processors such as QuARS. These tools assist in the systematic elicitation …
A Genetic Approach To Voltage Collapse Mitigation, Dwarakesh Nallan Chakravartula
A Genetic Approach To Voltage Collapse Mitigation, Dwarakesh Nallan Chakravartula
All Theses
The objective of this thesis is to provide an efficient and accurate corrective solution to a system that is on verge of voltage collapse. This thesis describes, in detail, the development of an optimization scheme that aims to alleviate power system instability and voltage collapse condition based on the principles of an evolutionary approach called Genetic Algorithm. The state of a system is determined using a voltage stability identifier termed Collapse Proximity Index (CPI) and the critical loading condition is identified. Applying principles of Genetic Algorithm, the critical system is brought back to a stable operating region. The sequential procedure …
A Voltage Flicker Suppression Device For Residential Air Conditioners And Heat Pumps, John Fox
A Voltage Flicker Suppression Device For Residential Air Conditioners And Heat Pumps, John Fox
All Theses
In some circumstances, voltage flicker due to the inrush current of residential heat pump can be a fairly visible to the residents as a slight flashing of the household's lights during the compressor starting event. The voltage flicker problem is caused by a variable contribution from sizable equivalent power system impedances and considerable inrush currents drawn by compressors. While this is not a new problem, and there are technologies on the market that attempt to alleviate the voltage flicker issue, no current solution attempts to correct for the problem at its root cause.
This thesis presents a device designed to …
User Study Of Information Extracted From Engineering Representations, Rachel Hannah
User Study Of Information Extracted From Engineering Representations, Rachel Hannah
All Theses
It is important for designers to understand the usefulness of different engineering representations in order to save time and money throughout a project. Designers often rely on past experience to decide which model to construct; yet students without this experience have no help. Interestingly there are noticeable gaps in the research literature with respect to how and when to select representations and modeling approaches for engineering designs. This thesis examines the differences between three types of engineering representations, specifically sketches, drawing packages, and physical prototypes. The amount of information designers can extract from these representations and also the correctness and …
The Effect Of A Surfactant Monolayer On Gas Exchange Across An Air-Water Interface During Mixed Convection, Richard Lee
The Effect Of A Surfactant Monolayer On Gas Exchange Across An Air-Water Interface During Mixed Convection, Richard Lee
All Theses
A set of laboratory experiments are presented that reveal the effect of a surfactant monolayer on the transport of oxygen across an air-water interface during mixed convection conditions. The experiments were conducted in a wind/water tunnel with water tanks of differing depth. Forced convection was imposed via the air flow, while natural convection was imposed by heating the water bulk above the air temperature. For the range of wind speeds being considered, mixed convection conditions resulted. Experiments were also conducted with only forced convection present. The data acquired during these experiments were used to develop a parameterization between the Sherwood …
Identifying And Comparing Key Process Attributes For Sustainable Building Delivery In India And The U.S., Prashanth Palanisamy
Identifying And Comparing Key Process Attributes For Sustainable Building Delivery In India And The U.S., Prashanth Palanisamy
All Theses
India is a rapidly developing nation with the associated brisk pace of construction. More sustainable building practices for construction in India would have social, environmental, and economic benefits. However, the key process attributes for successfully planning, designing, and constructing sustainable buildings in India are largely undefined. Other projects in India would benefit from a rigorous identification of these key process attributes which could help leapfrogging the sustainable building delivery in India to the best available practices.
Sustainable buildings require different delivery processes than traditional buildings; this can lead to process wastes due to unfamiliarity or incompatibility of the processes. These …
Identifying The Optimum Process Parameters Of Precision Glass Molding For Aspherical Lenses, Waqas Iqbal
Identifying The Optimum Process Parameters Of Precision Glass Molding For Aspherical Lenses, Waqas Iqbal
All Theses
The purpose of this research is to determine the optimum process parameters for the Precision Glass Molding (PGM) Process using Manufacturing Design, Design of Experiments and Metrology (for measuring the geometry of lenses). First, a custom machine is designed and manufactured which can carry out Precision Glass Lens Molding Experiments. This machine is then modified to improve temperature, position and force control. A literature review is performed to obtain data for process parameters that have been used in previous PGM studies. The collected data is then used in Design of Experiments to create twenty seven experiments that determine the optimum …
The Design Of An Ic Half Precision Floating Point Arithmetic Logic Unit, Balaji Kannan
The Design Of An Ic Half Precision Floating Point Arithmetic Logic Unit, Balaji Kannan
All Theses
A 16 bit floating point (FP) Arithmetic Logic Unit (ALU) was designed and implemented in 0.35µm CMOS technology. Typical uses of the 16 bit FP ALU include graphics processors and embedded multimedia applications.
The ALU of the modern microprocessors use a fused multiply add (FMA) design technique. An advantage of the FMA is to remove the need for a comparator which is required for a normal FP adder. The FMA consists of a multiplier, shifters, adders and rounding circuit. A fast multiplier based on the Wallace tree configuration was designed. The number of partial products was greatly reduced by the …
2-D And 3-D Assessment Of Cambered And Symmetric Airfoils: A Cfd Study, Tuncay Kamas
2-D And 3-D Assessment Of Cambered And Symmetric Airfoils: A Cfd Study, Tuncay Kamas
All Theses
A two dimensional and three dimensional computational study has been carried out respectively regarding aerodynamic forces affecting a symmetric airfoil, NACA0015 and a cambered airfoil, NACA2414. The negative lift (down force) and drag forces were predicted through the simulation of airflows over inverted rear-wings in different configurations namely; varying incidences i.e. angles of attack of the airfoils, two dimensional cross section of the inverted rear wings to be mounted on back of a car, and varying speeds of initial airflow.
The downforce increases as the angle of attack increases however, if an inverted rear wing is fixed on a car …
A Particle Swarm Optimization Using Random Keys For Flexible Flow Shop Scheduling Problem With Sequence Dependent Setup Times, Vinodh Sankaran
A Particle Swarm Optimization Using Random Keys For Flexible Flow Shop Scheduling Problem With Sequence Dependent Setup Times, Vinodh Sankaran
All Theses
In this research, a particle swarm optimization algorithm (PSO) using random keys is developed to schedule flexible flow lines with sequence dependent setup times to minimize makespan. The flexible flow line scheduling problem is a branch of production scheduling and is found in industries such as printed circuit board and automobile manufacturing. It is well known that this problem is NP-hard. For this reason, we approach the problem by implementing a particle swarm optimization (PSO), a metaheuristic which is inspired by the motion of a flock of birds or a school of fish searching for food. The proposed PSO has …
Principal Component Thermography For Steady Thermal Perturbation Scenarios, Rohit Parvataneni
Principal Component Thermography For Steady Thermal Perturbation Scenarios, Rohit Parvataneni
All Theses
The work focuses on the qualitative enhancement of Thermographic Inspection data using Principal Component Analysis technique. A new processing tool named Economical Singular Value Decomposition (SVD) is proposed for analyzing the infrared image sequences acquired from the test specimen.
Experiments are carried out on test sample using thermal excitation modalities such as flash, halogen and induction to create temperature variations. The infrared (IR) image sequence containing the information about the sample is captured using IR cameras. The acquired IR image sequences are processed using the proposed Economical SVD which projects the matrix of raw pixel values of image sequence into …
Modeling The Cooling Phase Of The Lens Molding Process, Saravanan Kannan
Modeling The Cooling Phase Of The Lens Molding Process, Saravanan Kannan
All Theses
The lens molding process is a relatively new technique used to manufacture lenses, in particular, high precision aspheric lenses. In order to achieve the desired size and shape of the lens, the cooling process after pressing must be controlled precisely because of the time and temperature dependent viscoelastic behavior of glass near and below the molding temperature. This thesis gives a detailed description of a three-dimensional computational model for analyzing the cooling phase of the lens molding process. Conduction, convection and radiation are considered in the model by coupling a computational fluid dynamics analysis of the flow of nitrogen through …
Experimental Characterization Of Stress Relaxation In Glass, Hemanth Kadali
Experimental Characterization Of Stress Relaxation In Glass, Hemanth Kadali
All Theses
Glass viscoelasticity has gained importance in recent years as glass lens molding appeared as a valuable alternative to the traditional grinding and polishing process for manufacturing glass lenses. In the precision lens molding process, knowledge of viscoelastic properties of glass in the transition region, which affect the stress relaxation behavior, is required to precisely predict the final size and shape of molded lenses. The purpose of this study is to establish a step-by-step procedure for characterizing the viscoelastic behavior of glass in the glass transition region using a finite term Prony series of a Generalized Maxwell model. This study focuses …
Comparing Problem-Based Learning And Lecture As Methods To Teach Whole-Systems Design To Engineering Students, Michael Dukes
Comparing Problem-Based Learning And Lecture As Methods To Teach Whole-Systems Design To Engineering Students, Michael Dukes
All Theses
The objective of this research is to compare problem-based learning and lecture as methods to teach whole-systems design to engineering students. A case study, Appendix A, exemplifying successful whole-systems design was developed and written by the author in partnership with the Rocky Mountain Institute. Concepts to be tested were then determined, and a questionnaire was developed to test students' preconceptions. A control group of students was taught using traditional lecture methods, and a sample group of students was taught using problem-based learning methods. After several weeks, the students were given the same questionnaire as prior to the instruction, and the …
Sensor-Based Soil Water Monitoring To More Effectively Manage Agricultural Water Resources In Coastal Plain Soils, Christopher Bellamy
Sensor-Based Soil Water Monitoring To More Effectively Manage Agricultural Water Resources In Coastal Plain Soils, Christopher Bellamy
All Theses
Cotton (Gossypium hirsutum L.) is widely grown in the United States with 5.7 million ha grown nationally and 1.2 million ha grown in the humid southeastern states in 2005. From 1969 to 2003, agricultural irrigated farmland acreage and total water applied increased by over 40% and 11% respectively to include a total of 55.3 million acres in 2002. Combined with recent and more frequent drought periods and legal water conflicts between states, there has been an increased interest in more effective southeastern water management, thus making the need to develop improved irrigation scheduling methods and enhanced water use efficiency of …
Charging Kinetics Of Electric Double Layer Capacitors, Clint Cagle
Charging Kinetics Of Electric Double Layer Capacitors, Clint Cagle
All Theses
A recent increase in the popularity of EDLCs and AC-EOF has necessitated a deeper understanding of the structure and charging kinetics of electrical double layers (EDLs) at electrode-electrolyte interfaces. Here, the charging kinetics of EDLs in nanoscale EDLCs is studied by a circuit model, a Poisson-Nernst-Planck (PNP) mo del, and molecular dynamics (MD) simulations. The results of the MD simulations demonstrate a linear charging behavior of EDLs near planar electrodes for both aqueous and organic electrolytes at charging below 90% and time larger than tens of picoseconds. Additionally, we will show that the circuit and PNP models are capable of …
Filtering Noise Caused By Sensor Selection For An Ultra-Wide Band Position Tracking System, Danyan Ganjali
Filtering Noise Caused By Sensor Selection For An Ultra-Wide Band Position Tracking System, Danyan Ganjali
All Theses
A filter designed to be optimal for alternating multi-sensor tracking systems is presented. This filter can be used on ultra-wide band position tracking systems such as the Ubisense system. In this thesis, a comprehensive evaluation of the accuracy of the Ubisense tracking system in a multi-room building is given. Then the multi-modality of the noise distribution of such a system is shown. A multi-sensor tracking system is then simulated and a Kalman filter is used to filter the measurements. It is shown that the Kalman filter is not optimal for such a system and the need for a filter that …
Robust Parameter Design And Finite Element Analysis For A Non-Pneumatic Tire With Low Vibration, Amarnath Proddaturi
Robust Parameter Design And Finite Element Analysis For A Non-Pneumatic Tire With Low Vibration, Amarnath Proddaturi
All Theses
During rolling of a non-pneumatic tire, vibration may be produced by the interaction of collapsible spokes with a shear deformable ring as they enter the contact region, buckle and then snap back into a state of tension. Other potential sources of vibration include the interaction of tire tread with the ground and ring vibration. In the present work, a systematic study of the effects of key geometric design parameters is presented using Taguchi's Robust Parameter Design Method and Orthogonal Arrays.
In the present work, a 2D planar finite element model with geometric non-linearity and explicit time-stepping is used to simulate …
Design And Analysis Of Alternating Spoke Pair Concepts For A Non-Pneumatic Tire With Reduced Vibration At High Speed Rolling, Shashank Bezgam
Design And Analysis Of Alternating Spoke Pair Concepts For A Non-Pneumatic Tire With Reduced Vibration At High Speed Rolling, Shashank Bezgam
All Theses
Recently, Michelin has invented an innovative non-pneumatic tire which has potential for improved handling, grip, comfort, and less rolling resistance when compared to a traditional pneumatic tire. The non-pneumatic wheel is manufactured from a molding process with integrated shear ring and collapsible spokes designed to provide optimal uniform ground contact patch with low rolling resistance. The shear band is constructed from a polyurethane material with imbedded inextensible reinforcements. During high speed rolling in initial testing, the original prototype showed high noise levels at frequencies above 100 Hz. A possible source of noise could be due to vibration initiated from the …
Vehicle-Infrastructure Integration (Vii) Enabled Plug-In Hybrid Electric Vehicles (Phevs) For Traffic And Energy Management, Xueying Kang
Vehicle-Infrastructure Integration (Vii) Enabled Plug-In Hybrid Electric Vehicles (Phevs) For Traffic And Energy Management, Xueying Kang
All Theses
Vehicle Infrastructure Integration (VII) program (also known as IntelliDrive) has proven the potential to improve transportation conditions by enabling the communication between vehicles and infrastructure, which provides a wide range of applications in transportation safety and mobility. Plug-in hybrid electric vehicles (PHEVs) that utilize both electrical and gasoline energy are a commercially viable technology with potential to contribute to both sustainable development and environmental conservation through increased fuel economy and reduced emissions. Considering positive potentials of PHEVs and VII in ITS, a framework that integrates PHEVs with VII technology was created in this research utilizing vehicle-to-vehicle and vehicle-to-infrastructure communications for …
Effectiveness Of Team-Building And Teamwork In Real And Virtual Worlds, Rachana Ranade
Effectiveness Of Team-Building And Teamwork In Real And Virtual Worlds, Rachana Ranade
All Theses
Given the increasing importance of globalization and collaboration, this research investigates the possibility of performing team-building training for globally dispersed teams using the capabilities of the virtual world Second Life. Three meeting conditions, the 3D virtual world Second Life, a combination of face-to-face and Second Life and face-to-face were evaluated. Thirty randomly assigned 3 person teams performed an ice-breaker session and then a team-building activity in each meeting condition. Four dependent variables were measured: task completion time; quality of task performance; the subjective satisfaction with the process based on group cohesiveness, perception of the process and satisfaction with the outcome; …
Relationships Between Lane Change Performance And Open-Loop Handling Metrics, Robert Powell
Relationships Between Lane Change Performance And Open-Loop Handling Metrics, Robert Powell
All Theses
This work deals with the question of relating open-loop handling metrics to driver-in-the-loop performance (closed-loop). The goal is to allow manufacturers to reduce cost and time associated with vehicle handling development. A vehicle model was built in the CarSim environment using kinematics and compliance, geometrical, and flat track tire data. This model was then compared and validated to testing done at Michelin's Laurens Proving Grounds using open-loop handling metrics. The open-loop tests conducted for model validation were an understeer test and swept sine or random steer test. Four commonly used handling metrics (steady state yaw rate gain, yaw rate damping …
Monitoring Co Concentration In Fuel Cells Using Microcantilever Sensors, Tugba Demir
Monitoring Co Concentration In Fuel Cells Using Microcantilever Sensors, Tugba Demir
All Theses
Estimating the concentration of gases including carbon monoxide (CO) in the hydrogen fuel exiting the reformer and entering the fuel cell is imperative. A high concentration of CO can cause fuel-cell catalyst poisoning, which permanently destroys the cell. Current practices call for utilizing expensive and bulky spectral analyzers to achieve this task. In addition to their high cost, these methodologies, undoubtedly, hinder the portability and self-containment of the cell. To overcome these problems and achieve the desired objectives of a portable, self-contained, and real-time measurement module, this thesis presents and experimentally investigates a new enabling technology based on utilizing an …
Straight Line Braking Performance Of A Road Vehicle With Non Linear Tire Stiffness Formulation, Anup Khekare
Straight Line Braking Performance Of A Road Vehicle With Non Linear Tire Stiffness Formulation, Anup Khekare
All Theses
The capability of a road vehicle equipped with an Anti-Lock Braking System (ABS) to come to a safe stop depends on factors such as dynamic force between tire and road, surface adhesion coefficient, and the vertical profile of the road. When in panic, a driver's reaction is to step hard on the brakes to make the vehicle stop as soon as possible. Although the use of modern technologies such as ABS and Electronic Stability Control (ESC) have reduced the number of accidents significantly, any further improvement in stopping distance would only complement these technologies.
Michelin has undertaken the development of …
Biological Treatment To Remove Color And Toxicity Of Effluent From The Manufacturing Of Navipol Yellow Gr, Larry French
Biological Treatment To Remove Color And Toxicity Of Effluent From The Manufacturing Of Navipol Yellow Gr, Larry French
All Theses
Navipol Yellow GR is an organic solvent azo dye manufactured by Sunbelt Corp. in Rock Hill, SC. The effluent generated from the manufacturing of this dye is highly colored, toxic, and contains trace solvents consisting of mixed xylene isomers and ethyl benzene. Traditional wastewater treatment systems are unable to remove the color and toxicity from the effluent. This study investigated using a sequential anaerobic / aerobic treatment system to decrease color and toxicity of the dye effluent. The anaerobic phase used bacteria cultures of Pseudomonas aeruginosa, Bacillus subtilis, Enterococcus faecalis, or Enterobacter aerogenes to decrease the color of the dye. …
Interactive Perception For Cluttered Environments, Robert Willimon
Interactive Perception For Cluttered Environments, Robert Willimon
All Theses
Robotics research tends to focus upon either non-contact sensing or machine manipulation, but not both. This paper explores the benefits of combining the two by addressing the problem of extracting and classifying unknown objects within a cluttered environment, such as found in recycling and service robot applications. In the proposed approach, a pile of objects lies on a flat background, and the goal of the robot is to sift through the pile and classify each object so that it can be studied further. One object should be removed at a time with minimal disturbance to the other objects. We propose …
A Logistic Regression Model To Predict Incident Severity Using The Human Factors Analysis And Classification System, Hrishikesh Kavade
A Logistic Regression Model To Predict Incident Severity Using The Human Factors Analysis And Classification System, Hrishikesh Kavade
All Theses
The Human Factors Analysis and Classification System (HFACS) is used to help identify causal factors that lead to human error. The framework has been used in a variety of industries to identify leading contributing factors of unsafe events, such as accidents, incidents and near misses. While traditional application of the HFACS framework to safety outcomes has allowed evaluators to identify leading causal issues based on frequency, little has been done to gain a more comprehensive view of the system's total risk. This work utilizes the concept of event severity along with the HFACS framework to help better identify target areas …
Analysis Of Distributed Denial Of Service Attacks And Countermeasures, Sampada Karandikar
Analysis Of Distributed Denial Of Service Attacks And Countermeasures, Sampada Karandikar
All Theses
Network technology has experienced explosive growth in the past two decades. The vast connectivity of networks all over the world poses monumental risks. The generally accepted philosophy in the security world is that no system or network is completely secure [1] which makes network security a critical concern. The work done in this thesis focuses on Distributed Denial of Service Attacks (DDoS) where legitimate users are prevented from accessing network services. Although a lot of research has been done in this field, these attacks remain one of the most common threats affecting network performance.
One defense against DDoS attacks is …
Mechanical And Chemical Characterization Of Biological Composite Structures, Bonnie Zimmerman
Mechanical And Chemical Characterization Of Biological Composite Structures, Bonnie Zimmerman
All Theses
A better understanding of the bioresponse of naturally occurring systems will help
to optimize the engineering of synthetic biomaterials. The aim of this thesis was to
characterize the mechanical and chemical behavior of two distinct biological composite
systems, human teeth and wool fibers. These mechanical and chemical properties were
also studied as a function of natural structure and environmental conditions.
Human teeth are composite systems consisting primarily of hydroxylapatite and
protein. This project investigated how the use of clinical dental treatments and
procedures, such as whitening and etching, affects mechanical properties. Analysis of
nanoindentation with the Oliver-Pharr model provided elastic …