2010 Bowman Scholars
Division of Engineering and Weapons
1/C Tyrell W. Arment
- Major: Mechanical Engineering
- Title: The Effects of Thermal Barrier Coating, Common Rail Injection, and Reduced Compression Ratio on the Efficiency of Single-Cylinder Diesel Engines
- Advisors: Associate Professor Jim S. Cowart - Mechanical Engineering Department, Assistant Professor Patrick A. Caton - Mechanical Engineering Department
The Effects of Thermal Barrier Coating, Common Rail Injection, and Reduced Compression Ratio on the Efficiency of Single-Cylinder Diesel Engines
The purpose of this project is to explore several current technologies that can be used to increase the efficiency of small diesel engines for the use in small unmanned aerial vehicles. The specific technologies investigated in this study will be common-rail direct-injection, thermal barrier coatings, and reduction in compression ratio. It is anticipated that these technologies will work together to increase the overall efficiency of a Yanmar L48V diesel engine. Previous applications of thermal barrier coatings in larger diesel engines have proven to be effective in reducing thermal losses and driving up the overall efficiency of engines. Preliminary calculations have shown that due to the reduced thermal losses, thermal barrier coatings will not only increase the efficiency of the engine, but will also allow for the investigation of how a reduction in compression ratio on small diesel engines affects their efficiency.
Reducing the compression ratio of these small diesel engines has never fully been explored; however, there is limited data gathered from large, multi-cylinder engines that indicates engine efficiency can be improved using this technique. According to this data, a peak in efficiency occurs at a compression ratio of approximately 16:1. The Yanmar engine will have its compression ratio progressively stepped down from its current value of 20.6:1 to 16:1 in an attempt to validate the hypothesis that efficiency peaks at this lower compression ratio.
The final part of this study is to incorporate a common-rail fuel injection system onto the Yanmar engine. Common-rail direct-injection is believed to boost the efficiency of the engine due to its high pressure present at its injection nozzles which causes a finer, more efficiently burned spray. Making a finer spray is not the only benefit of the common-rail system. Unlike standard mechanical injection systems that inject fuel at fixed times and apply the entire shot of fuel at once, modern common-rail systems store high pressure fuel in a reservoir that can be injected at times determined by a computer controlled system. This setup allows for optimization of the timing of injection for the various stages of engine operation: startup, wide open throttle, and cruise.
With all three separate technologies showing potential for an increase in efficiency, the study takes the quest for greater efficiency one step further and investigates how these technologies can work together to increase efficiency even more notably in a small diesel engine.
1/C Justin A. DeVillar
- Major: Electrical Engineering and Computer Science
- Title: Reduction in Constraints on Subjects for Iris Recognition
- Advisors: Associate Professor Robert W. Ives - Electrical and Computer Engineering Department, Visiting Professor James R. Matey - Electrical and Computer Engineering Department
Reduction in Constraints on Subjects for Iris Recognition
The human iris is one of the most unique physical structures of the human body that is available for biometric recognition. As such its applications are becoming increasingly widespread in identification and security applications. Outside of private security applications, iris scan units have been deployed with US Military troops in Afghanistan and Iraq and positioned at major access control points in countries such as the United Arab Emirates.
Though it is one of the most powerful forms of biometric identification, iris recognition development has been met by many constraints. One of these constraints is the standoff distance at which a device is capable of gathering useful data from a subject. Development of optics, sensors and illumination sources has brought the current record for distance at which useful data can be collected to greater than 30 meters. As further development is made and implemented, surveillance of large areas such as terminals, stations and checkpoints will become more practical.
This project will focus on the acceleration of image acquisition and increasing its range. This will be accomplished with the use of a camera with a wide field of view to detect a subject and locate his eyes. This information will then be used to direct the high power optics to the target to capture an image to be processed for recognition.
Such a system would reduce the impact of implementing iris recognition surveillance on subjects. Increasing the distance at which images can be captured and processed would eliminate the need to funnel people through a line or even stop them during the procedure. The use of a second camera to direct the primary unit to the iris would allow the device to capture images at an increased rate and make it possible to conduct surveillance in large crowds. The increased distance would also improve probability of obtaining data from subjects, such as terrorists and fugitives, who would otherwise be uncooperative.
The implementation of this device could potentially help to prevent future incidents such as the London subway bombings. It would also be helpful in reducing the time for personnel to be processed through security checkpoints.
1/C Timothy J. Gruber
- Major: Ocean Engineering
- Title: Applications of Tubercles in Marine Tidal Turbines
- Advisor: Professor Emeritus Michael E. McCormick - Naval Architecture and Ocean Engineering Department
Applications of Tubercles in Marine Tidal Turbines
This project will research the feasibility and practicality of using small ridges, called tubercles on the leading edge of water mill blades to improve efficiencies on hydro-kinetic power plants. Kinetic tidal power is one of the newest clean energy sources brought onto the global power grid, and the use of tubercles offers an immediate opportunity to increase efficiency by a significant percentage. The research plan is to spend the fall semester conducting computer simulations to identify likely configurations and predict improvements in performance, while spending the spring semester conducting scale tests in the 120 foot and 380 foot tow tanks to verify the computer analysis. The application of tubercles to kinetic tidal turbines has never been tried before.
1/C Peggy S. LeGrand
- Major: Mechanical Engineering
- Title: Environmentally Assisted Cracking Evaluation of Alloy IN686 Using Constant Extension Rate Testing
- Advisor: Associate Professor Michelle G. Koul - Mechanical Engineering Department
Environmentally Assisted Cracking Evaluation of Alloy IN686 Using Constant Extension Rate Testing
Monel, K500, fasteners have been used in the Navy for many years. Under cathodic protection, the K500 fasteners become subject to environmentally assisted cracking (EAC). Inconel 686 is a nickel alloy that shows great potential as a replacement fastener. To test the susceptibility of IN686 to EAC and hydrogen embrittlement, a series of constant extension rate tests will be run in air, for baseline data, and then in ASTM D1141 seawater until failure. The tests will be run with various levels of potential using a potentiostat to simulate the cathodic protection. The suitability of the IN686 will be determined by using reduction in area (%) and elongation at fracture (%). Next the broken samples will undergo fractography using the scanning electron microscope (SEM) to determine if the mode of failure has changed. If there is extra time at the end of the semester, more work will be done to determine the fracture toughness of the IN686 and EAC in the presence of a sharp crack. IN686 is expected to perform well in the constant extension rate testing; however, very little work has been done on the fracture toughness. If the IN686 performs well, it might eventually replace K500 as a marine fastener in cathodically protected environments.
1/C Timothy J. Omlor
- Major: Mechanical Engineering
- Title: Improved Methodology for Crack Arrest Fracture Toughness Testing
- Advisor: Professor Richard E. Link - Mechanical Engineering Department
Improved Methodology for Crack Arrest Fracture Toughness Testing
The crack arrest fracture toughness is the ability of a material to stop a fast running crack as it travels through the material. This is an important property for analyzing the fracture safety of nuclear reactor pressure vessels. The current test procedure as prescribed by the American Study for Testing and Materials for testing crack arrest properties of ferrous materials uses a notched specimen. A wedge is driven into a hole in front of the notch which causes a brittle crack to initiate from the notch and across the thickness of the specimen. Ideally the crack arrests before reaching the back of the specimen. The crack arrest toughness is calculated using measurements of the specimen deformation and the arrested crack length.
This test method offers many challenges and does not consistently yield valid results. The objective of MIDN Omlor’s research is to improve the testing methods for measuring the crack arrest fracture toughness. He will characterize materials used as brittle crack starters to better match specific crack starter welds with the material under investigation to promote more reliable crack initiation at predictable deformation levels. The results of this investigation will be used to guide revisions to the ASTM E1221, Standard Method for Measuring the Plane-Strain Crack Arrest Toughness of Ferritic Materials.
1/C Matthew A. Porter
- Major: Electrical Engineering
- Title: Optimizing High Power DC-DC Converter Design Utilizing SiC Field Effect Transistors and Nanocrystalline-Structured Alloy Cores
- Advisors: Associate Professor John G. Ciezki - Electrical and Computer Engineering Department, Associate Professor Thomas E. Salem - Electrical and Computer Engineering Department
Optimizing High Power DC-DC Converter Design Utilizing SiC Field Effect Transistors and Nanocrystalline-Structured Alloy Cores
Current civilian and military power distribution applications are increasingly turning to the utilization of DC power transmission as a high efficiency alternative to traditional AC distribution schemes. A central factor which dominates the performance characteristics of these schemes is the implementation of power converters, which are necessary to modulate voltage and current waveforms within the grid. The dominant form of converter in use in DC distribution applications today is known as the Switched Mode Power Converter (SMPC), which utilizes high frequency semiconductor switches and magnetic components to modulate power. Traditionally, these devices have been constructed using Silicon (Si) and ferrite materials. However, given the increased power and efficiency demands of modern DC distribution design requirements, these materials have reached their upper physical limitations of performance, and undesired trade-offs must made between efficiency, power density and power-throughput to accomplish design goals. This project intends to research two alternative materials for the construction of these components and the benefits which they offer to SMPC design. Silicon Carbide (SiC) and nanocrystalline-structured alloys are currently being researched to supplant Si and ferrite, respectively, within semiconductor switches and magnetic components in SMPCs. The material properties of SiC and nanocrystalline-structured alloys promise to increase efficiency and maximum power throughput while maximizing power density within SMPCs. This project will design SMPCs using a circuit configuration known as a Full-Bridge topology, chosen specifically for its optimal performance characteristics and pertinent naval applications. These converters will be used to study the effects of components using SiC and nanocrystalline alloys upon the design space. Two converters will be built, one as a control converter for comparison utilizing traditional Si components known as Metal Oxide Field Effect Transistors (MOSFETs) and a ferrite transformer core and a second implementing SiC MOSFETs and a nanocrystalline-structured alloy transformer core. Each converter will be evaluated upon the metrics of efficiency, power density and thermal performance for a range of power-throughput levels. The design space will be characterized for each converter using these metrics. It is expected that SiC and nanocrystalline will significantly improve the converter design space, expanding it into regions which were previously unobtainable utilizing Si MOSFETs and ferrite cores without significant trade-offs between the performance parameters under evaluation.
1/C Matthew L. Roberts
- Major: Aerospace Engineering
- Title: Determination of the Error Induced by Platform Vibrations on a Directed Energy Beam System
- Advisors: Commander R. Joseph Watkins, USN - Mechanical Engineering Department, Professor Oscar Barton, Jr. - Mechanical Engineering Department, Visiting Professor Craig E. Steidle - Aerospace Engineering Department
Determination of the Error Induced by Platform Vibrations on a Directed Energy Beam System
The Directed Energy Weapons Program at the Office of Naval Research (ONR) is a potential “game changer” of modern naval warfare that will dramatically increase U.S. capability while decreasing the risk of collateral damage. Beam control is one of the five main fields of study in this program and is essential for the development and operation of a directed energy weapon system, especially when operating in the air or on the sea in a combat maritime environment. Directed energy beams are highly susceptible to jitter, the deviation of a light beam from its intended path due to platform induced vibrations and atmospheric effects. The United States Naval Academy (USNA) has developed the Directed Energy Beam Control Laboratory which will be used in this research project to study the correction of jitter in an optical beam. In order to correct jitter caused by mechanical vibrations without feedback from the target, the exact position and orientation of the platform must be determined in real time. The position will be resolved to micrometer precision and the orientation to microradian levels in a time step of 500 microseconds or less. It will be measured by optical sensors and/or accelerometers. The primary objective will be to develop the necessary algorithms and sensor placements that are suitable for predicting the platform induced error in the directed energy beam in real time. This research project will measure the accuracy of the error prediction and how quickly the computer is able to implement these algorithms. Eventually, this error prediction could allow for correction of platform induced jitter without feedback from the target. Knowing this error in real time will improve the aimpoint maintenance on the target and significantly reduce the power required for a directed energy weapon system.
1/C Kayla J. Sax
- Major: Systems Engineering (Honors)
- Title: Characterization and Comparison of New Concepts in Neutron Detection
- Advisors: Professor Martin E. Nelson - Mechanical Engineering Department, Professor Svetlana Avramov-Zamurovic - Weapons and Systems Engineering Department, CAPT Charles B. Cameron, USN - Electrical and Computer Engineering Department, Visiting Research Professor James F. Ziegler - Physics Department
Characterization and Comparison of New Concepts in Neutron Detection
Radiation can cause the information stored on a digital memory cell to change. As a consequence, these memory cells have the potential to serve as radiation detectors. Since commercially available memory chips are designed to minimize radiation influence, the chips must be modified in order to increase their sensitivity to neutrons. This is accomplished by increasing the probability that an incident neutron will cause a change in the digital information stored on the chip indicating the presence of radiation. The objective of this project is to evaluate both unmodified and modified memory chips for sensitivity to neutrons, comparing them to conventional detection systems, in an effort to establish their potential for general scientific use.
As part of this project, seven detection systems will be evaluated. This includes four non-powered detectors, namely thermoluminescent dosimeters, foil activation detectors, bubble detectors, and track-etch devices. In addition, a powered 3He proportional counter will be tested. These five conventional detectors will serve as points of comparison for unmodified and modified 4Mb Honeywell memory cells. Each detection system will be exposed to three neutron sources for three variable lengths of time per source. Based on the data obtained from these experiments, statistical analysis will be performed in order to establish each detector’s sensitivity, including a confidence interval and the minimum and maximum sensitivity.
It is expected that the unmodified memory chip will be fairly insensitive to neutrons at the incident energies available for study. The modified chips, however, are expected to outperform all of the other detection systems. If successful, this project will establish the fact that sensitivity-enhanced memory chips can be used as ultra-sensitive, ultra-low-powered neutron detectors. Memory cell based detection system have the potential to improve existing technologies and enable important new applications—especially use as a system of Nuclear-WMD monitors for cargo containers, capable of detecting the presence of SNM, localizing the cargo container, and communicating the information via satellite.
1/C William P. Stillman III
- Major: Aerospace Engineering
- Title: Numerical Simulation of Ship Air Wakes
- Advisor: Captain Murray R. Snyder, USN - Mechanical Engineering Department
Numerical Simulation of Ship Air Wakes
The United States Naval Academy presents a unique opportunity for Ship Air Wake research. The ability to do in situ testing on USNA YP’s for comparison with computational fluid dynamics simulations is not available at other facilities. This project will begin to create and validate a process for developing sea-based helicopter launch and recovery envelopes with the aid of computational fluid dynamics (CFD). The current method for generating rotary craft launch and recovery envelopes is primarily through actual flight testing, which is prohibitively expensive and frequently difficult to schedule and accomplish. My project will primarily consist of analyzing CFD data that was generated in the summer of 2009 by me and two other Midshipmen interns at NAVAIR Naval Air Station Pax River. This data will provide a preliminary understanding of ship air wake turbulence in the wake of a USNA YP. Concurrent with my analysis, experiments will be conducted on a model of a YP in the USNA wind tunnel. Comparison of the CFD results with those from the wind tunnel will help validate the accuracy of the CFD analysis that was performed. Subsequently, starting in the late fall 2009, testing will be done on a modified USNA YP to generate correlations between the CFD and wind tunnel data. If both the CFD and in situ testing agree substantially, the CFD may eventually be proven as a trusted substitute for wind tunnel testing and, perhaps, for flight testing. A flight envelope generated by validated CFD analysis may prove to be more accurate, cheaper, and more time-efficient than one generated through full flight testing.
1/C Daniel G. Wheaton
- Major: Systems Engineering (Honors)
- Title: Dynamic Control of the Naval Academy's Competition AUV
- Advisor: Captain John W. Nicholson, USN - Weapons and Systems Engineering Department
Dynamic Control of the Naval Academy's Competition AUV
USNA’s AUV is currently a solid platform in hardware. Unfortunately there has been little work done on modeling the system dynamically in the water. This is partially due to its very difficult non-linear behavior and that previous teams have focused on perfecting the hardware. During the first semester the project will focus on perfecting low level control. Developing closed loop RPM control for the thrusters, and perfecting the heading, pitch, and depth compensators will be the initial primary focus. During the spring, higher level control will be investigated, using the already developed framework for high level controllers to give commands to lower level compensators. This will provide the ability for the AUV to autonomously change its mission and therefore its behavior during the AUVSI AUV competition in 2010. Accomplishing these tasks will include developing a non-linear transfer function for the Tecnadyne model 300 thruster and experimentally determining the dynamic parameters of the AUV as it moves through the water. Upon completion of a solid low level control of the system, hierarchal control will be implemented. This will allow the AUV to actively change its mission in order to accomplish the wide variety of tasks required for it to be competitive in San Diego. The final deliverable of this project will be a competition ready AUV that is capable of autonomously navigating through multiple tasks during the summer of 2010.
1/C Matthew J. Wilder
- Major: Electrical Engineering
- Title: The Design and Control of an Ultracapacitor/Battery Storage System to Optimize Battery Life
- Advisor: Associate Professor John G. Ciezki - Electrical and Computer Engineering Department
The Design and Control of an Ultracapacitor/Battery Storage System to Optimize Battery Life
Efficient energy storage has become vital in the design and implementation of hybrid and electric vehicles. Major obstacles in developing commercially competitive electric/hybrid vehicles are the cost and life expectancy of the battery banks. Lead-acid batteries are often utilized because of their low cost and easy recycling. Despite this advantage, the deep-cycling current demands during acceleration (high rate of discharge) soften the active positive material present in the battery, reducing its electrical conductivity and deactivating the material. The end result is a shortening of battery life. This project aims to offer a solution to the battery dilemma. The introduction of a hybrid ultracapacitor/battery energy storage system can more readily accommodate a high rate of discharge in the electric vehicle system. The system will help maintain the battery current constant via feedback control, thereby decreasing internal source losses and increasing battery life. When the driver of one of these types of vehicles presses the accelerator, the motor controller current increases to meet the demands of the operator. As the motor controller current increases, a sensor will detect the increased demand which forces a bi-directional converter to supply current to the system via the ultracapacitor bank to maintain an almost constant output at a sensor detecting the battery’s output current. This almost constant draw of current from the battery is the desired effect that increases battery life. Ultracapacitors are a fairly recent invention and their advances have opened new opportunities in efficient energy storage. Ultracapacitors have an increased energy density as compared to electrolytic capacitors but in turn have a lower power density. The power density offered is 10 to 20 times that a lead-acid battery, while its energy density is 10 to 100 times that of conventional capacitors. The project’s main goal will be to maintain a constant current demand from the system’s battery bank during a jump in motor controller current for a specified duration of time. This will first be done using a unidirectional DC/DC converter. A secondary goal will be the implementation of a bidirectional converter, which enables recharging of the ultracapacitor bank during braking and more modest battery operating currents. The proposed research will entail the selection of the current sensors, the sizing of the ultracapacitor bank, converter topology, development and implementation of the control algorithm via simulation, and finally a demonstration of the controlled discharge.
Division of Math and Science
1/C Keith R. Hollis
- Major: Quantitative Economics
- Title: Optimal Allocation of Land Conservation Resources for the Maryland Rural Legacy Program
- Advisor: Assistant Professor Sommer E. Gentry - Mathematics Department
Optimal Allocation of Land Conservation Resources for the Maryland Rural Legacy Program
As populations begin to condense around urban areas, the state of Maryland has begun to fight the process of urban sprawl through the institution of the “Maryland Rural Legacy Program.” This program is designed to practice land conservation through the process of acquiring large, contiguous land tracts and strategically located plots of land. In these efforts to help preserve Maryland’s natural beauty and ecosystem, the state has allocated funds up to 31 million dollars in recent years to spend strictly on the buying of land, and the state looks to add more than 200,000 more acres of environmentally critical land by 2011.
The proposed research course would put in practice a real world example of Operations Research and optimization. The project is designed to investigate the investment in these lands that produce food, provide scenic open space, act as wildlife habitats and are sources of clean water. As the program gains footing, the amount of land purchased is increasing. However, the purchasing of these lands is done based on individual assessment, and has not been looked at as an optimization problem. For these reasons, the project goal would be to develop, using real public record data, a program that objectively determines a process for land acquisitions and protection agreements in a cost efficient manner. This would eliminate the subjective process by which lands are now targeted and acquired and ultimately maximize the amount of environmentally critical land Maryland can obtain given their budget.
In our evaluation of environmental worth, Professor Gentry and I will use criterion such as size, location, wildlife habitat, green infrastructure and water quality and utilize Microsoft Excel to solve these complex optimization problems. As environmental worth is not always reflected monetarily, our model will weigh the monetary costs with actual received benefit environmentally from acquiring the land. We will also factor in many other variables that affect a plots environmental worth and make the model easily adaptable to sudden changes or environmental shocks that may occur. In addition to the factors that may affect environmental worth, we will weigh unique constraints presented by each plot and ultimately develop a program that will help determine, given a number of plots, which ones should be targeted for acquisition. The end product of our research will be a model that will help maximize the amount of environmentally critical land the State of Maryland can acquire in the current and future periods.
1/C Frederick R. Tolle
- Major: Physics
- Title: Study of Acoustic Landmine Detection Using a Parametric Array
- Advisor: Professor Murray S. Korman - Physics Department
Study of Acoustic Landmine Detection Using a Parametric Array
A VS 1.6 landmine will be buried 2.5 cm deep in dry sifted masonry sand in a concrete box. A microphone placed directly over the surface will measure the incident pressure. A LDV will detect the vibrations on the surface of the sand at different scan locations. The LDV to microphone rms response ratio will be used to measure the “on target” and “off target” results. The results using the parametric array’s highly directional, low frequency signal will be compared with the omni-directional subwoofer results to quantify any improvements in detection.
During the second semester of research, we intend to bury small, solid spherical objects to simulate clutter in the soil. This measure will be an attempt to determine if detection improves with a narrower sound beam. By insonifying the area, sound will be reverberated by the buried metal targets, and experimentation will be performed to determine whether a narrower beam reduces distortion.