Engineering Commons^™

Development And Testing Of The Rigidizable Inflatable Get-Away-Special Experiment, Brady D. O'Neal

Theses and Dissertations

The purpose of this research project is to develop the Rigidizable Inflatable Get-Away-Special Experiment (RIGEX) from a computer-based model into a space-qualified prototype. Past research projects have developed RIGEX's command and control, structural analysis, and integration with the orbiter. This thesis details the organization, assembly, and test planning for the RIGEX protoflight model. Strict requirements imposed by the National Aeronautics and Space Administration (NASA) must be fulfilled for any payload to travel into space. Based on the requirements set forth by NASA documentation, this thesis establishes appropriate assembly procedures for the construction of a space payload. Detailed design changes are …

Final Development, Testing, And Flight Preparation Of The Rigidizable Get-Away-Special Experiment (Rigex), Zachary R. Miller

Theses and Dissertations

The purpose of this research is to support the final development of the Rigidizable Inflatable Get-Away-Special Experiment (RIGEX). The RIGEX program is an experimental initial step in developing large-scale rigidizable inflatable structures, which can be utilized in space applications. The primary intent of RIGEX is to verify and validate ground testing of inflation and rigidization methods for inflatable space structures against a zero-gravity space environment. This is performed by designing a Canister for All Payload Ejections (CAPE) experiment to collect data on space rigidized structures for validation of ground testing methods. The results presented in this thesis provide documentation needed …

A Comparison Of Film Cooling Techniques In A High Speed, True Scale, Fully Cooled Turbine Vane Ring, Michael J. Umholtz

Theses and Dissertations

An effort was undertaken to understand the impact of different film cooling configurations in a true scale turbine vane for three proprietary airfoil designs. The measurements for this study were taken at the United States Air Force Turbine Research Facility (TRF). The TRF enabled heat transfer data to be obtained on full scale turbine hardware under realistic engine conditions. The surface heat flux of the turbine blades was analyzed using the impulse response method. The overall effectiveness was compared between airfoil types at 60% span over varying streamwise locations on both suction and pressure surfaces. Using an approximated massflow, a …

Effects Of Prior Aging At 191°C On Creep Response Of Im7/Bmi 5250-4, Robert A. Salvia

Theses and Dissertations

The creep behavior of IM7/BMI 5250-4 with fiber orientations of [± 45] and [0/90] that were aged in air at 191 °C for up to 1000 hours was evaluated. The total weight loss during the aging process was also evaluated. Weight loss due to aging was 0.64% for the [0/90] fiber orientation and 0.72% for the [± 45] fiber orientation. Tensile tests to failure were conducted to establish tensile properties. The [0/90] specimens have a much higher stiffness and Ultimate Tensile Strength (UTS) values than the [± 45] specimens. The tensile tests of the aged specimens revealed that the Ultimate …

Critical Life Prediction Research On Boron-Enhanced Ti-6al-4v, Kevin A. Schwendiman

Theses and Dissertations

Research on boron-enhanced Ti-6-4 has demonstrated the following improvements to the Ti-6-4 alloy: up to 40% increase in ultimate tensile strength, up to 30% increase in modulus/stiffness, while maintaining greater than 10% ductility at RT conditions. The increased properties are attributed to small additions of boron (-or= wt%), which refine the microstructure and result in a small volume fraction (~6 vol%) of fine TiB whiskers. Previous research indicates potential for substantial improvements in fatigue, fatigue crack growth, and fracture toughness. However, uncertainty regarding these second-tier mechanical properties is currently limiting implementation of this class of titanium alloys. This study of …

Optimal Noise Matching For Mutually-Coupled Arrays, Michael A. Jensen, Karl F. Warnick

Faculty Publications

From classical two-port noise theory, the noise figure of an amplifier is minimized when a source is matched to a particular optimal reflection coefficient at the amplifier input. In this paper, we show that this result extends in a natural way to the multiport case, with a coupled N-port source network such as an array antenna connected by a multiport matching network to the inputs of N low-noise amplifiers. For optimal noise performance, the matching network must decouple the array and present isolated, individually noise-matched ports to the amplifier inputs.

Continuous Steel Production And Apparatus, Kent D. Peaslee, Jörg Peter, D. G. C. Robertson, Brian G. Thomas, Lifeng Zhang

Materials Science and Engineering Faculty Research & Creative Works

A process for continuous refining of steel via multiple distinct reaction vessels for melting, oxidation, reduction, and refining for delivery of steel continuously to, for example, a tundish of a continuous caster system, and associated apparatus.

Retrofit Of The Louisa-Fort Gay Bridge Using Cfrp Laminates, Ching Chiaw Choo, Tong Zhao, Issam E. Harik

Kentucky Transportation Center Research Report

This report details the processes pertaining to the repair and strengthening of the Louisa-Fort Gay Bridge, Lawrence County, KY, using advanced composite materials. Site inspections revealed flexural cracks in the reinforced concrete girders of the continuous bridge structure. To determine the cause of these cracks, an evaluation was initiated based on vehicle classification and truck weight data. The results confirmed that certain reinforced concrete girders were stressed beyond the limits allowed by the AASHTO Code. A retrofit scheme using carbon fiber reinforced polymer (CFRP) composite was devised and the amount of CFRP laminates needed for flexural strengthening was determined from …

Improve Safety Of Workers During Highway Construction And Maintenance, Donn E. Hancher, Kenneth Bussey, Robin Meagher, Jonathan Ross, Kristin Smith

Kentucky Transportation Center Research Report

There is an inherent risk of injury or fatality in all occupations. Even secretarial occupations face jobsite hazards such as carpal tunnel and back injury. The nature of the construction industry combined with the required physical demand and rigorous work processes, make it an industry with higher risk of injury or fatality. In an effort to decrease that inbuilt jobsite risk that construction workers face, this study will analyze the current best safety practices, examine new safety technologies, and collaborate with construction workers themselves to gain a better perspective of what jobsite hazards they face.

Specifically, this study will focus …

An Experimental Investigation Of Parallel Multimedia Streams Over Ieee 802.11e Wlan Networks Using Txop, Nicola Cranley, Tanmoy Debnath, Mark Davis

Conference papers

In this paper we perform an experimental investigation of the IEEE 802.11 TXOP facility to enhance the transmission of parallel multimedia streaming sessions through efficient bandwidth reservation and explicitly consider both the audio and video streams. The delay constraints associated with the audio and video streams that comprise a multimedia session pose the greatest challenge since real-time multimedia is particularly sensitive to delay as the packets require a strict bounded end-to-end delay. We show how the TXOPlimit parameter can be efficiently dimensioned to reduce the tranmission delay for the video frames. Due to tis frame-based nature, video applications are considered …

Rare: Resource Aware Routing For Mesh, Karol Kowalik, Brian Keegan, Mark Davis

Conference papers

An important element of any routing protocol used for Wireless Mesh Networks (WMNs) is the link cost function used to represent the radio link characteristic. The majority of the routing protocols for WMNs attempt to accurately characterise the radio link quality by constructing the link cost function from the measurements obtained using active probing techniques, which introduces overhead. In this paper we propose a new approach called Resource Aware Routing for mEsh (RARE) which instead employs passive monitoring to gather radio link information. This results in a smaller overhead than the other methods that require active network probing, and is …

Use Of Reflective Armbands To Improve Adolescent Pedestrian And Pedalcyclist Safety, Nancy Dunaway, Eric R. Green, Jerry G. Pigman, Monica L. Barrett

Kentucky Transportation Center Research Report

The objective of this effort was to determine if elementary and middle school students could be educated to use reflective armbands to increase their visibility to motorists while walking or bicycling to school. The number of armbands and surveys distributed totaled slightly over 7,000. Responses were received from approximately 12 percent (873) of the pre-surveys and slightly over 3 percent (119) of the post-surveys. Respondents to the survey indicated nearly 15 percent of schoolchildren receiving reflective armbands were wearing the armband “every day” or “most days”. Of the parents responding, 21 percent indicated their children would continue to wear the …

Compaction Of Mixtures Of Hard Rocks And Soft Shales And Non-Durable Shales Using Impact Compactors, Tommy C. Hopkins

Kentucky Transportation Center Research Report

Impact roller compaction has been used to improve embankment and highway subgrades in South Africa, Australia, Europe, and China and other areas of the world. In September of 2003, the International Technology Scanning Program, sponsored by the Federal Highway Administration (FHWA), the American Association of State Highway and Transportation Officials (AASHTO), and the National Cooperative Highway Research Program of the Transportation Research Board, identified this technology as one of several foreign technologies and innovations that could significantly benefit U.S. transportation systems. The technology was high-lighted at the Fifth International Conference on the Bearing Capacity of Roads and Airfields in 1998 …

Tuning Magnetic Microstructures Of Reference Layer In Magnetic Tunneling Junctions, L. Yuan, Y. S. Lin, Dexin Wang, Sy-Hwang Liou

Materials Research Science and Engineering Center: Faculty Publications

Magnetic microstructures in the reference layer in magnetic tunneling junctions (MTJs) are tuned by a reversal field under ambient conditions to investigate their effects on the magnetoresistance (MR) and the exchange coupling field (H_E) between the reference layer and the free layer. Magnetization changes in the reference layer can be probed by measuring minor MR loops. The results show the H_E of the minor MR loops versus the applied reversal field changes from negative to positive and crosses zero. These results can be explained by the magnetic inhomogeneities at the interface between anti-ferromagnetic/pinned-ferromagnetic layers, which causes the …

Ferromagnetic Multipods Fabricated By Solution Phase Synthesis And Hydrogen Reduction, Y. C. Sui, Y. Zhao, Sitaram S. Jaswal, Xingzhong Li, David J. Sellmyer

Materials Research Science and Engineering Center: Faculty Publications

A simple approach combining pyrolysis and hydrogen reduction is formulated for making ferromagnetic-branched nanostructures called Co multipods. The CoO multipods (branched nanostructures) were produced through the pyrolysis of cobalt-oleate in octadecane at 280 °C with the presence of oleic acid under the protection of pure nitrogen. The angles between the nearest arms are 90°. After the reduction of the branched CoO nanostructures in flowing hydrogen gas in a tubular oven at 290°C, the CoO is reduced to pure cobalt with hexagonal crystal structure and the branched shapes are retained. Anisotropic magnetic properties were found for cobalt multipods on silicon substrates.

Magnetization Reversal In Cubic Nanoparticles With Uniaxial Surface Anisotropy, Ralph Skomski, Xiao-Hui Wei, David J. Sellmyer

Materials Research Science and Engineering Center: Faculty Publications

The effect of surface anisotropy on the magnetization reversal in small magnetic particles is investigated. The model considers particles of cubic shape cut from a tetragonal crystal with cube faces in the (001) and equivalent planes. In particles having diameters of less than about 10 nm, the coercivity approaches the Stoner–Wohlfarth limit, but the anisotropy field differs from that of the bulk of the particles. With increasing particle size, the nucleation modes acquire the character of magnetic surface or bulk modes that reduce the coercivity.

Effective Demagnetizing Factors Of Complicated Particle Mixtures, Ralph Skomski, George C. Hadjipanayis, David J. Sellmyer

Materials Research Science and Engineering Center: Faculty Publications

Demagnetizing factors have been calculated for hierarchical mixtures and dispersions of magnetic particles, such as columns of platelike particles in a matrix and clusters of spherical particles. The theory involves a number of shape and density parameters describing particles, aggregates, and matrix. It approximates distant particles by a homogeneous medium and yields closed and easy-to-use expressions for the effective demagnetizing factor.

Continuous/Cluster-Pinned Recording Media, Ralph Skomski, M. L. Yan, Yinfan Xu, David J. Sellmyer

Materials Research Science and Engineering Center: Faculty Publications

We propose and theoretically investigate a new class of nanostructured magnetic recording films, cluster-pinned recording media. The films consist of magnetic clusters exchange coupled to a continuous hard layer with perpendicular anisotropy and low coercivity. Our calculations yield the coercivity and the cross-track correlation length as a function of film thickness and pinning density and strength. The mechanism is very similar to the Gaunt–Friedel pinning in bulk magnets, which differs from ordinary strong pinning by the selfconsistent dependence of wall curvature and coercivity on defect concentration. The main difference is the exponent for the coercivity as a function of the …

Transceiver Design And Radio Frequency Integrated Circuits Evaluation Via Electronic Design Automation, Yu Ming Chen

Masters Theses

This thesis study presents the theory and design methodology of Radio Frequency Integrated Circuits (RFIC) and analyzes a RF frond-end receiver and down-conversion mixers using circuit evaluation tools. The theory of RF is described on both architectures and circuit levels with respect to monolithic implementation in integrated semiconductor technologies. The design methodology provides an efficient and practical way to approach ·the theoretical values by using an Electronic Design Automation (EDA) tool called Cadence Virtuoso custom design platform Based on the libraries provided by the Cadence Virtuoso, a Heterodyne receiver and two Gilbert mixer circuits have . been evaluated through the …

Data Fusion Technique For Measuring Intersection Delay Using Gps-Enabled Probe Vehicles, Byung-Hee Han

Masters Theses

Intersection control delay is considered a primary measure for determining the level of service at signalized intersections. This thesis develops a technique estimating intersection delay using GPS data from GPS-enabled vehicles. First, this study analyzes existing methods that estimate control delays using GPS data and proposes an improved technique in response to the weakness of those methods. The proposed method estimates the control delay well with better accuracy covering the weaknesses. However, the control delay from the GPS data has a sample size problem for determining the level of service at signalized intersections. Therefore, this thesis proposes a data fusion …

Stockpiling Hydrated Lime-Soil Mixtures, Tommy C. Hopkins, Tony L. Beckham, Charlie Sun

Kentucky Transportation Center Research Report

The concept and feasibility of stockpiling and reusing hydrated lime-soil mixtures to stabilize particular areas on stabilization projects after the mixing contractor has departed were examined. In chemical stabilization of subgrades, situations often arise where additional areas need to be stabilized after the specialty contractor and mixing equipment have left the project. Field and laboratory investigations were performed to determine if a soil mixed with hydrated lime during routine lime subgrade stabilization could be mixed, stockpiled, and used later. In laboratory studies, hydrated lime-soil mixtures were stockpiled loosely in the laboratory. CBR specimens of the stockpile material were remolded and …

Simulated Effects Of Marathon Training On Bone Density, Remodeling, And Microdamage Accumulation Of The Femur, Scott J. Hazelwood, Alesha B. Castillo

Biomedical Engineering

Stress fractures are mechanically induced injuries resulting from fatigue damage to bone due to repetitive loading and are common injuries occurring in runners. In this study, we used computer simulations of marathon training programs to examine the effects of endurance running on femoral density, remodeling, and microdamage accumulation. Simulated remodeling activity increased in the femoral neck and proximal cortex and predicted microdamage increased in all regions examined after 16 weeks for each program. Daily running for three years produced more microdamage than the advanced training schedule over the same time period. Areas of high remodeling and damage corresponded to clinically …

Swarm Intelligence For Transmission System Control, Ganesh K. Venayagamoorthy, Ronald G. Harley

Electrical and Computer Engineering Faculty Research & Creative Works

Many areas related to power system transmission require solving one or more nonlinear optimization problems. While analytical methods might suffer from slow convergence and the curse of dimensionality, heuristics based swarm intelligence can be an efficient alternative. This paper highlights the application of swam intelligence techniques for solving some of the transmission system control problems.

Digital Ripple Correlation Control For Photovoltaic Applications, Jonathan W. Kimball, Philip T. Krein

Electrical and Computer Engineering Faculty Research & Creative Works

Ripple correlation control (RCC) is a fast, robust online optimization technique. RCC is particularly suited for switching power converters, where the inherent ripple provides information about the system operating point. The present work examines a digital formulation that has reduced power consumption and greater robustness. A maximum power point tracker for a photovoltaic panel demonstrates greater than 99% tracking accuracy and fast convergence.

Flatness-Based Feedback Linearization Of A Synchronous Machine Model With Static Excitation And Fast Turbine Valving, E. C. Anene, U. O. Aliyu, J. Levine, Ganesh K. Venayagamoorthy

Electrical and Computer Engineering Faculty Research & Creative Works

This paper focuses attention on the concept of flatness-based feedback linearization and its practical application to the design of an optimal transient controller for a synchronous machine. The feedback linearization scheme of interest requires the generation of a flat output from which the feedback control law can easily be designed. Thus the computation of the flat output for reduced order model of the synchronous machine with simplified turbine dynamics is hereby presented. The corresponding linearized compensator is derived as well as the nonlinear controller for transient stabilization of a synchronous machine subjected to large disturbances. The transient behavior of a …

Magnetic Equivalent Circuit Modeling Of Induction Motors, S. D. Sudhoff, Brian T. Kuhn, Keith Corzine, Brian T. Branecky

Electrical and Computer Engineering Faculty Research & Creative Works

Finite element models are invaluable for determining expected machine performance. However, finite element analysis can be computationally intense; particularly if a large numbers of studies or high bandwidth studies are required. One method to avoid this difficulty is to extract machine parameters from the finite element model and use the parameters in lumped parameter models. While often useful, such an approach does not represent space harmonics or asymmetries in the motor. A methodology for constructing a state-variable model, based on a magnetic equivalent circuit of the motor is described herein. In addition, the parameters for this model are based solely …

A Novel Impedance Measurement Technique For Power Electronic Systems, Peng Xiao, Ganesh K. Venayagamoorthy, Keith Corzine

Electrical and Computer Engineering Faculty Research & Creative Works

When designing and building power systems that contain power electronic switching sources and loads, system integrators must consider the frequency-dependent impedance characteristics at an interface to ensure system stability. Stability criteria have been developed in terms of source and load impedance for both dc and ac systems and it is often necessary to measure system impedance through experiments. Traditional injection-based impedance measurement techniques require multiple online tests which lead to many disadvantages. The impedance identification method proposed in this paper greatly reduces online test time by modeling the system with recurrent neural networks. The recurrent networks are trained with measured …

Engineering Management And Industrial Engineering: Similarities And Differences, Cassandra C. Elrod, Ashley Rasnic, William Daughton

Business and Information Technology Faculty Research & Creative Works

Engineering Management is a broad and diverse field of engineering, thereby making it difficult to define exactly what the degree encompasses. At the same time, the somewhat related degree of Industrial Engineering is better understood. Some universities offer a Bachelor of Science degree in Engineering Management with an emphasis in Industrial Engineering, while others offer a Bachelor of Science degree in Industrial Engineering with an emphasis in Engineering Management. In today's world of competitive academia, many wonder if these degree fields are similar enough to be used interchangeably or if there is a distinct difference separating the two degrees, making …

A First Course In Power: Can A Single Course Serve All Students?, Mariesa Crow, Badrul H. Chowdhury, Keith Corzine, Mehdi Ferdowsi

Electrical and Computer Engineering Faculty Research & Creative Works

This paper is part of a panel entitled "Modernizing the First Course in Power Systems." In this paper the authors discuss the first power course requirement at the University of Missouri-Rolla. Undergraduate students are required to take a power course, but they may select between a power systems course or a electromechanical conversion course.

Intelligent Techniques For Planning Distributed Generation Systems, S. Santoso, Nitish Saraf, Ganesh K. Venayagamoorthy

Electrical and Computer Engineering Faculty Research & Creative Works

Including distributed generation (DG) in distribution systems often requires in-depth analysis and planning. This panel paper will present a few issues related to the planning of distributed generation, and will describe how intelligent systems methods can be used to help solve these issues. Investment and operating cost minimization, capacity determination and siting of distributed generators, islanding of power systems with DG, coordination of voltage regulators and capacitors with distributed generators in regulating feeder voltage profiles are a few subjects discussed in the paper.