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Articles 1021 - 1050 of 1237
Full-Text Articles in Engineering
Investigation Of Training Algorithms For Hidden Markov Models Applied To Automatic Speech Recognition, Eric Fang
All Theses
The work presented in this thesis focuses on simulating a speech recognizer which is trained by different people with different speaking styles and investigates how sensitive the training and recognition processes are to the variations in the training data. There are four main parts to this work. The first involves an experiment of weighting methods for training with multiple observation sequences. The second involves the testing of different initial parameters. The third part includes the first experiment involving training with multiple observation sequences. The model's sensitivity to variations in training data was evaluated by comparing the cases of different values …
An Evaluation Of Function-Based Representations And Information Archival In Engineering Design, Benjamin Caldwell
An Evaluation Of Function-Based Representations And Information Archival In Engineering Design, Benjamin Caldwell
All Theses
Recent research in function-based design includes the development of a vocabulary of functions, the Functional Basis, and a repository of products and their functions. Many design tools are being developed around this vocabulary and repository to support conceptual design. The usefulness of these tools, however, is dependent on the quality of the vocabulary and the information contained in the repository. In this research, both the vocabulary and the repository are empirically evaluated to understand their strengths and limitations. A statistical analysis is performed on function models in the repository to determine the frequency of usage of Functional Basis terms. It …
A Pulsatile Bioreactor For Conditioning Tissue Engineered Heart Valves, Leslie Sierad
A Pulsatile Bioreactor For Conditioning Tissue Engineered Heart Valves, Leslie Sierad
All Theses
Tissue engineered constructs with autologous adult stem cells capable of self-repair and growth are highly desired replacements for diseased heart valves. However, the current approaches have inadequate mechanical properties to withstand in vivo implantation. Therefore, our group hypothesized that an in vitro environment of physiological intra-cardiac pressures and flow will stimulate stem cells to differentiate and remodel valvular scaffold constructs before implantation.
The group developed a pneumatic-driven conditioning system (Aim I) consisting of a three-chambered heart valve bioreactor, a pressurized compliance tank, a reservoir tank, one-way valves, pressure-retaining valves, and pressure transducers. The system can be sterilized using conventional autoclaving …
The Effect Of Bond Strength Of Flexible Laminates On Puncture Resistance, Rijosh Cheruvathur
The Effect Of Bond Strength Of Flexible Laminates On Puncture Resistance, Rijosh Cheruvathur
All Theses
This work was aimed at understanding whether the bond strength of laminates will affect the puncture resistance of the laminate. Even though a strongly bonded adhesive layer in between two webs will considerably improve the mechanical properties of the laminate compared to that of the individual materials, there is a general belief in the packaging industry that having a lower bond strength helps to improve the bending or, in other words, the flexibility of the laminate thereby increases the tear and puncture resistance.
Laminations of aluminum foil and polyethylene terephthalate (PET) were used as a model system to determine the …
Experimental Study Of The Three-Stream Scalar Mixing In A Turbulent Coaxial Jet, Matthew Dinger
Experimental Study Of The Three-Stream Scalar Mixing In A Turbulent Coaxial Jet, Matthew Dinger
All Theses
In the present study we investigate three-stream scalar mixing in a turbulent coaxial jet. In
this flow the center jet and the annulus, consisting of acetone-doped air and ethylene respectively, are
mixed with the co-flow air. A unique aspect of this study compared to previous studies of three-scalar
mixing is that two of the scalars (the center jet and air) are separated from the third (annulus);
therefore, this flow better approximates the mixing process in a nonpremixed turbulent reactive
flow. Planar laser-indiced fluorescence and Rayleigh scattering are employed to measure the mass
fractions of the acetone-doped air and ethylene, respectively. …
Wide Operating Range For A Circular Waveguide Probe In Spherical Near-Field Measurements, Xiong Wang
Wide Operating Range For A Circular Waveguide Probe In Spherical Near-Field Measurements, Xiong Wang
All Theses
This thesis discusses spherical near-field measurements implemented by a circular waveguide probe which has much shorter length and wider operating range than those proposed similar circular probes. A brief introduction of spherical near-field measurement techniques is provided first. We also introduce the well-known conclusion that utilizing first-order probes simplifies the measurements and associated near-field to far-field transformation. Accordingly, a relatively short circular waveguide probe antenna is designed and fabricated. Detailed fields of this probe are analyzed to demonstrate that it is still a first-order probe even though the length is short. Furthermore, it radiates only first-order fields over a wide …
Fast Generation Of Receiver-Based Statistics In Frequency Hop Radios Without Decoder Simulation, Michael Masse
Fast Generation Of Receiver-Based Statistics In Frequency Hop Radios Without Decoder Simulation, Michael Masse
All Theses
Receiver-based statistics can contain useful information about the quality a wireless channel. We examine methods of generating receiver statistics without real-time simulation of the receiver and the decoder, particularly during a network-level simulation. Attention is restricted to a receiver employing binary orthogonal signaling, noncoherent demodulation, and a soft-decision decoder in a frequency-hop network. Data is gathered from off-line simulations of channel, demodulation, and decoding processes, using a family of turbo product codes. Study and analysis of the data are used to characterize the behavior of the receiver statistics and determine on-line methods of generating the statistics in network-level simulations. To …
Independent Torque Distribution Management Systems For Vehicle Stability Control, Indrasen Karogal
Independent Torque Distribution Management Systems For Vehicle Stability Control, Indrasen Karogal
All Theses
Vehicle Dynamics Control (VDC) systems, also called Electronic Stability Control (ESC) systems, are active on-board safety systems intended to stabilize the dynamics of vehicle lateral motion. In so doing, these systems reduce the possibility of the driver's loss of control of the vehicle in some critical or aggressive maneuvers. One approach to vehicle dynamics control is the use of appropriate drive torque distribution to the wheels of the vehicle. This thesis focuses on particular torque distribution management systems suitable for vehicles with independently driven wheels.
In conducting this study, a non-linear seven degree-of-freedom vehicle model incorporating a non-linear tire model …
Nonlinear Finite Element Analysis Of Tweel Geometric Parameter Modifications On Spoke Dynamics During High Speed Rolling, Maya Ramachandran
Nonlinear Finite Element Analysis Of Tweel Geometric Parameter Modifications On Spoke Dynamics During High Speed Rolling, Maya Ramachandran
All Theses
The acoustic signature and noise produced by non-pnuematic wheels such as the Michelin TWEELTM is a critical design criteria for automotive and other mobility applications. The TWEELTM structure consists of three basic parts: (1) a circular deformable 'shear beam', (2) collapsible spokes and (3) a rigid hub. During high speed rolling the TWEELTM produces acoustic noise which is hypothesized to be due to resonant vibration of the TWEELTM spokes as they enter the contact region, buckle and then snap back into a state of tension. In order to identify and help understand the causes of acoustic noise for a rolling …
Modeling, Analysis And Control Of Flexible Solid-State Hysteretic Actuators, Kushan Vora
Modeling, Analysis And Control Of Flexible Solid-State Hysteretic Actuators, Kushan Vora
All Theses
A distributed parameters modeling and control framework for flexible solid-state hysteretic actuator is presented in this work. For the simplicity of analysis, the actuator dynamic behavior is decoupled and treated separately from the hysteresis nonlinearity. To include the effects of widely-used flexural mechanisms, a mass-spring-damper boundary condition is considered for system. Moreover, the effect of electromechanical actuation is included as a concentrate force at the boundary. The problem is then divided into two parts: first part deals with free motion analysis of system in order to obtain eigenvalues and eigenfunctions using the expansion theorem and a standard eigenvalue problem procedure. …
Investigation Of The Merging Of Two Axisymmetric Turbulent Jets, Jeffrey Smith
Investigation Of The Merging Of Two Axisymmetric Turbulent Jets, Jeffrey Smith
All Theses
A study was done to determine the converging distance of two axisymmetric turbulent jets and to compare the experimental results with the Reichardt hypothesis. This experiment consisted of measuring the velocity profiles of the two jets and manipulating the momentum ratio between the jets. Through testing, it was determined that the Reichardt hypothesis while efficient, over predicts the converging distance of the jets by up to 25% in some cases.
An Acoustic Doppler Velocimeter (ADV) was used to take measurements across the path of the jets and monitored the velocity and the turbulent kinetic energy. After observing the velocity profiles, …
An Investigation On Spot-Weld Modeling Complexity For Crash Simulation, Srinivasan Vimalanathan
An Investigation On Spot-Weld Modeling Complexity For Crash Simulation, Srinivasan Vimalanathan
All Theses
In order to design car body structures which are safe during crash, modern automotive manufacturers perform both full-scale experimental crash tests and computer simulation of vehicle crash events using commercially available Finite Element Analysis (FEA) packages such as ABAQUS or LS-DYNA. Use of crash simulations significantly reduces the number of real time crash experiments needed and reduces the time required for design changes. However, in order to capture accurately crash behavior during high-speed impact, a large amount of detailed FEA modeling features such as number and types of elements, mesh element size, number of components, different types of connectors, material …
Optimal Maintenance Crew Composition And Enhancement Of Crew Productivity, Robert Schober
Optimal Maintenance Crew Composition And Enhancement Of Crew Productivity, Robert Schober
All Theses
The South Carolina Department of Transportation (SCDOT) dedicates a large portion of its budget and other resources to the maintenance of the State's transportation infrastructure. In order to maximize the efficiency and productivity of the State's highway maintenance workforce, the SCDOT partnered with Clemson University to research the performance of these maintenance crews. The goal of this research is to identify optimal crew compositions, if possible, and to suggest potential crew productivity enhancement methods.
Data was collected from the SCDOT Highway Maintenance Management System (HMMS) and crew rankings were developed based on several pre-determined performance criteria. These rankings were then …
Analysis Of In-Flight Vibration For A Turbo Propeller Aircraft, Kyle Dunno
Analysis Of In-Flight Vibration For A Turbo Propeller Aircraft, Kyle Dunno
All Theses
A data recorder was utilized to record in-flight vibration of a turbo propeller aircraft. The data recorded produced power spectral density (PSD) profiles which are currently used in laboratory settings to drive vibration tables in order to simulate a particular vehicle type. Overall Grms values from the averaged data were then statistically compared to published standards and other studies to determine if there were differences in overall Grms values.
The data recorder was rigidly mounted to the cargo area of the turbo propeller aircraft. Thirty flights were recorded which varied in flight time from less than one hour to greater …
Circuit Modules For Six-Port Reflectometer On Chip, Chaojiang Li
Circuit Modules For Six-Port Reflectometer On Chip, Chaojiang Li
All Theses
Broadband signal generator is an indispensable module for broadband Six-Port Reflectometer (SPR). To integrate a whole SPR system on a chip, the source must be compact. In this thesis, a three-stage voltage-controlled oscillator (VCO), using two parallel weak invertor-chain oscillators and sense amplifiers, is proposed and designed in a 0.13 µm CMOS process. These two parallel weak inverter-chain oscillators extend the low frequency operating range and the sense amplifiers expand the high frequency operation. The measurement results show that the oscillator can be tuned from 430 MHz to 12 GHz, which satisfies the targeted SPR operating frequency range.
In order …
Optimal And Heuristic Resource Allocation Policies In Serial Production Systems, Ramesh Arumugam
Optimal And Heuristic Resource Allocation Policies In Serial Production Systems, Ramesh Arumugam
All Theses
We have studied the optimal server allocation policies for a tandem queueing system under different system settings. Motivated by an industry project, we have studied a two stage tandem queueing system with arrival to the system and having two flexible servers capable of working at either of the stations. In our research, we studied the system under two different circumstances: modeling the system to maximize throughput without cost considerations, modeling the system to include switching and holding costs along with revenue for finished goods. In the maximizing throughput scenario, we considered two different types of server allocations: collaborative and non-collaborative. …
The Effect Of Montmorillonite Nanoclay On Mechanical And Barrier Properties Of Mung Bean Starch Films, Bianca Stiller
The Effect Of Montmorillonite Nanoclay On Mechanical And Barrier Properties Of Mung Bean Starch Films, Bianca Stiller
All Theses
Starch is an interesting biodegradable polymer due to its excellent film forming properties, availability, and low cost. On the other hand, starch films are often limited by their poor mechanical properties, and water resistance. The addition of montmorillonite clays have improved these properties in both petroleum and biodegradable films.
The objective of the research was to determine the effect of montmorillonite clay on the mechanical and barrier properties on mung bean starch films.
The addition of 5% clay yielded the optimum balance between mechanical and barrier properties of these composite films with improved tensile strength (TS) of 20.8763± 0.789 MPa, …
Computational Analysis Of Input-Shaping Control Of Microelectromechanical Mirrors, Thomas Starling
Computational Analysis Of Input-Shaping Control Of Microelectromechanical Mirrors, Thomas Starling
All Theses
Advances in micromachining technology have enabled the design and development of high performance microelectromechanical systems (MEMS). There is a pressing need for control techniques that can be used to improve the dynamic behavior of MEMS such as the response speed and precision. In MEMS applications, open-loop control is attractive as it computes a priori the required system input to achieve desired dynamic behavior without using feedback, thus eliminating the problems associated with closed-loop MEMS control. While the input-shaping control is attractive due to its simplicity, the effectiveness of this control approach depends on the accuracy of the model that is …
P-M Characteristics Of Reinforced Concrete Sections, Paul Johnson
P-M Characteristics Of Reinforced Concrete Sections, Paul Johnson
All Theses
This manuscript presents two parametric studies which were performed to evaluate a provision which originated in the 1994 Uniform Building Code (UBC). This provision states that if gravity-induced axial loads carried by a reinforced concrete member are greater than 35% of the pure axial load-carrying capacity (Po) of that member, then the member cannot be used as part of the lateral force resisting system (LRFS). Along with the UBC provision, the Structural Engineers Association of California's (SEAOC) Blue Book states that the value of 0.35Po corresponds to the level of axial load representing a balanced state of strain, i.e., the …
Finite Element Analysis Of Carbon Fiber Composite Ripping Using Abaqus, Joy Pederson
Finite Element Analysis Of Carbon Fiber Composite Ripping Using Abaqus, Joy Pederson
All Theses
An energy dissipation system is proposed for use on consumer passenger automotive vehicles and auto racing stock cars. This system will be utilized to protect the occupants from frontal impacts with stationary or near stationary objects. The system will be affixed to the front of the car's primary structure. It is proposed to replace the traditional steel bumper currently in use. This system will not increase the weight of the car, nor will it adversely affect the aerodynamics of the body. The system will improve the crashworthiness of the vehicle. Advanced composites will be the primary sacrificial element in the …
An Integrated Routing And Distributed Scheduling Approach For Hybrid Ieee 802.16e Mesh Networks For Vehicular Broadband Communications, Rahul Amin
All Theses
An integrated routing and distributed scheduling approach for fast deployable IEEE 802.16e networks is presented where distributed base stations with dual radios form a mesh backhaul and subscriber stations communicate through these base stations. The mesh backhaul is formed via an IEEE 802.16e mesh mode radio on each base station, while the subscriber stations communicate with base stations via PMP mode radios. The proposed routing scheme divides the deployed network into several routing zones. Each routing zone contains several base stations that form the mesh backhaul with one base station equipped with either a fiber, satellite or any other point-to-point …
Transmission Error Analysis And Avoidance For Ieee 802.15.4 Wireless Sensors On Rotating Structures, Jobin Jacob
Transmission Error Analysis And Avoidance For Ieee 802.15.4 Wireless Sensors On Rotating Structures, Jobin Jacob
All Theses
Wireless sensors are increasingly adopted in manufacturing and vehicular systems for monitoring critical components under continuous operation. Many such components move rapidly and frequently in metallic containments with challenging radio propagation characteristics.
For wireless sensors mounted on rotating structures, previous studies identified an eminent increase in packet transmission errors at higher rotation speeds. Such errors were found to occur at specific locations around the rotating spindle's periphery and such locations depended sensitively on sensor location and surrounding geometry. This thesis presents a systematic study of the expected packet error rates due to such errors, and analytically derives the first transmission …
Development Of A Quadrotor Testbed For Control And Sensor Development, Abhishek Bhargava
Development Of A Quadrotor Testbed For Control And Sensor Development, Abhishek Bhargava
All Theses
A quadrotor is an under actuated unmanned aerial vehicle (UAV) which uses thrust from four rotors to provide six degrees of freedom. This thesis outlines the development of a general purpose test bed that can be used for sensor and control algorithm development. The system includes the means to simulate a proposed controller and then a hardware in the loop implementation using the same software. The test bed was assembled and verified with a linear controller for both attitude and position control using feedback from an IMU (Inertial measurement Unit) and a Global Position System (GPS) sensor.
The linear controller …
Synchrophasor's Application In State Estimation, Linwood Ross
Synchrophasor's Application In State Estimation, Linwood Ross
All Theses
This thesis presents an investigation into the effect of synchrophasor measurements on the accuracy of a state estimator. Two state estimation algorithms have been developed in Matlab and tested on several systems. The first state estimator is the traditional non-linear estimator that is currently being used by most utilities. The second estimator is a hybrid linear state estimator. A bad data detection algorithm has been developed as well to determine the effect of synchrophasor measurements in bad data detection. A total of seven different systems are used for testing the proposed algorithms. Six systems are used in testing the bad …
Analysis Of Speed-Related Crashes Using Event Data Recorder Data, Swathi Korpu
Analysis Of Speed-Related Crashes Using Event Data Recorder Data, Swathi Korpu
All Theses
Safety in general is defined as 'the absence of unintended harm to living creatures or inanimate objects' (Evans, 2004). Traffic safety is measured in terms of motor vehicle crashes. A crash is an unplanned event which results in either fatality, or injury or property damage. Of all the factors that contribute to a crash, speed is a major issue, as more than 31 percent of all fatal crashes involve speeding (NHTSA, 2007). The speed-safety relationship can be determined by knowing the effect of speed on the frequency and severity of crashes. The relationship between speed and frequency of crashes is …
Design Of An Ic Controller For A Light Emitting Diode Stack, Andrew Alleman
Design Of An Ic Controller For A Light Emitting Diode Stack, Andrew Alleman
All Theses
An integrated circuit (IC) powering up to nine series connected high brightness light emitting diodes (HBLED's) was designed. The LED's are split into three groups by color (RGB), and the average current through each group is independently varied using a separate microprocessor in conjunction with the IC controller. Integrated comparators compare the voltage across each LED group with internally generated references to check for open or short circuit diodes. In the event of an open circuit failure, the IC controller switches in a SCR to bypass the open circuit device thus maintaining light output at reduced intensity.
Silvaco CAD tools …
Effect Of Nitrification On Lead Corrosion In Chloraminated Distribution Systems, Michael Shade
Effect Of Nitrification On Lead Corrosion In Chloraminated Distribution Systems, Michael Shade
All Theses
Water treatment facilities have been shifting from using chlorination to chloramination as a primary disinfectant since 2004, when the EPA enacted the Disinfectants/Disinfection By-Products (D/DBP) Rule mandating the decrease of DBPs. After the switch to chloramination, an unexpected lead concentration increase was detected in the Washington, D. C., and Greenville, NC water systems. These increases may be associated with the switch from chlorination to chloramination. Decomposition of chloramines results in higher ammonia loading to drinking water distribution systems, which may increase nitrification. Nitrifying bacteria may facilitate lead corrosion via two mechanisms: use of nitrite or nitrate as an alternative electron …
Modeling Of Space-Charge-Limited Current Injection Incorporating An Advanced Model Of The Poole-Frenkel Effect, Satoshi Takeshita
Modeling Of Space-Charge-Limited Current Injection Incorporating An Advanced Model Of The Poole-Frenkel Effect, Satoshi Takeshita
All Theses
The current flow due to Space-Charge-Limited (SCL) emission is well known and the associated current-voltage power law relationship can be observed in many materials, particularly in insulators and semiconductors. Under an applied field, the space-charge effect occurs due to the carrier injection, and the resulting current due to the presence of the space-charge effect is referred to as SCL current. In the SCL current theory, the presence of localized traps in a material has a significant effect on the transport of injected carriers; however, in the first order SCL model, the trap barrier height is assumed to be constant for …
Ultracapacitor Assisted Powertrains: Modeling, Control, Sizing, And The Impact On Fuel Economy, Dean Rotenberg
Ultracapacitor Assisted Powertrains: Modeling, Control, Sizing, And The Impact On Fuel Economy, Dean Rotenberg
All Theses
This thesis investigates possible fuel economy gains attainable by a combination of high-power density ultracapacitors (also called supercapacitors) and an induction motor integrated into a conventional vehicle powertrain for power assistance.
Periods of quick acceleration require a much higher power output from an automobile than what is encountered under more typical driving conditions. A simple kinetic energy calculation can show that accelerating a 2000 kg vehicle (roughly the size of a Ford Explorer SUV) from 0 to 60 mph in 10 seconds requires almost 70 kW of power, in addition to the power needed to overcome road and air drag …
Accelerated Life Testing Of Electronic Revenue Meters, Venkata Chaluvadi
Accelerated Life Testing Of Electronic Revenue Meters, Venkata Chaluvadi
All Theses
Electricity meters are devices that continuously record electrical energy consumption. In the past, meters have been of electromechanical type and consisted windings and moving parts. Electromechanical meters tend to be bulky, less accurate and more susceptible to tampering. As with other aging power system infrastructure in the US, most electricity meters are around 40 years old and are nearing the end of their intended lifespan. Concerns over the accuracy of these electromechanical meters along with advances in technology have led to development of new electronic meters which have additional benefits such as light weight, tamper-proof mechanisms, harmonic detection and Advanced …