Engineering Commons^™

A Functional Basis For Engineering Design: Reconciling And Evolving Previous Efforts, Julie Hirtz, Robert B. Stone, Daniel A. Mcadams, Simon Szykman, Kristin L. Wood

Mechanical and Aerospace Engineering Faculty Research & Creative Works

In engineering design, all products and artifacts have some intended reason behind their existence: the product or artifact function. Functional modeling provides an abstract, yet direct, method for understanding and representing an overall product or artifact function. Functional modeling also strategically guides design activities such as problem decomposition, physical modeling, product architecting, concept generation, and team organization. A formal function representation is needed to support functional modeling, and a standardized set of function-related terminology leads to repeatable and meaningful results from such a representation. We refer to this representation as a functional basis; in this paper, we seek to reconcile …

Defect And Mixed Conductivity In Nanocrystalline Doped Cerium Oxide, Toshio Suzuki, Igor Kosacki, Harlan U. Anderson

Materials Science and Engineering Faculty Research & Creative Works

The results obtained from a study on the microstructure and the electrical properties of Gd-doped CeO₂ thin films were reported. Dense, nanocrystalline films on sapphire substrates are prepared using a polymeric precursor spin coating technique. The electrical conductivity was studied as a function of temperature and oxygen activity and correlated with the grain size. For nanocrystalline Gd-doped CeO₂ thin films, the ionic conductivity increased with decreasing activation energy as the grain size decreased. A conductivity model was developed to analyze PO₂ behavior of the electrical conductivity. Using the conductivity model, the hopping energy of electron conduction and …

Biological Fixed Film Systems, Mark W. Fitch, Ellen England

Civil, Architectural and Environmental Engineering Faculty Research & Creative Works

No abstract provided.

A Congestion Controlled Logical Topology For Multihop Optical Networks, U. Bhattacharya, D. Datta, Badrul H. Chowdhury, G. C. Saha, B. K. Sikdar

Electrical and Computer Engineering Faculty Research & Creative Works

This paper considers the problem of designing the logical topology for any wavelength routed optical network, given the traffic matrix. An heuristic algorithm is proposed here for designing topologies based on the De-Bruijn graph and we compare our results with those obtained through the deterministic approach. The De-Bruijn graph is selected in this context as the logical topology due to some of its characteristic features like simple routing scheme, low diameter and small degree.

Intelligent Control Of Turbogenerator Exciter/Turbine On The Electric Power Grid To Improve Power Generation And Stability, Ganesh K. Venayagamoorthy, Ronald G. Harley, Donald C. Wunsch

Electrical and Computer Engineering Faculty Research & Creative Works

A review of the applications of intelligent control to replace/augment the conventional excitation and/or turbine control of turbogenerators on the electric power grid is presented in the paper. The intelligent controller designs are based on neural networks and adaptive critic designs (ACDs). The feedback variables are completely based on local measurements from the generators. Simulations and some practical laboratory implementations on a single-machine-infinite-bus and a three-machine power system demonstrate that intelligent controllers are much more effective than the conventional PID control for improving dynamic performance and stability of the power grid under small and large disturbances. The safety margins on …

A New Control Strategy For The Unified Power Flow Controller, Lin Zhang, Liangying Dong, Mariesa Crow

Electrical and Computer Engineering Faculty Research & Creative Works

The unified power flow controller (UPFC) is the most versatile among a variety of flexible AC transmission system (FACTS) devices, which can be used for power flow control, enhancement of transient stability, damping system oscillations and voltage regulation. In this paper, we propose a new PI based approach for the dynamic control of UPFC. With the new control strategy, not only the active and reactive power flow control but also the system oscillations damping can be achieved. The digital simulation results developed in MATLAB and PSCAD/EMTDC environments are presented to verify the efficiency of the proposed control algorithm.

Speedup Of Self-Timed Digital Systems Using Early Completion, Scott C. Smith

Electrical and Computer Engineering Faculty Research & Creative Works

An Early Completion technique is developed to significantly increase the throughput of NULL Convention self-timed digital systems without impacting latency or compromising their self-timed nature. Early Completion performs the completion detection for registration stage i at the input of the register, instead of at the output of the register as in standard NULL Convention Logic. This method requires that the single-rail completion signal from registration stage i+1 , Ko i+1 , be used as an additional input to the completion detection circuitry for registration stage i , to maintain self-timed operation. However, Early Completion does necessitate an assumption of equipotential …

State Dependent Riccati Equation Based Spacecraft Attitude Control, Ming Xin, S. N. Balakrishnan

Mechanical and Aerospace Engineering Faculty Research & Creative Works

We present a new optimal control approach to the robust spacecraft attitude control in the framework of State Dependent Riccati Equation (SDRE) technique. To treat this highly nonlinear control system, we formulate it as a nonlinear optimal regulator problem. SDRE technique was well applied to this class of attitude control problem. We also synthesize a neural network based extra controller to achieve the robustness in the presence of the parameter uncertainties. A general spacecraft attitude regulation problem was studied to show the effectiveness of SDRE approach and robust extra control design. © 2002. Published by the American Institute of Aeronautics …

Proper Orthogonal Decomposition Based Optimal Control Design Of Heat Equation With Discrete Actuators Using Neural Networks, Radhakant Padhi, S. N. Balakrishnan

Mechanical and Aerospace Engineering Faculty Research & Creative Works

A new method is presented for the optimal control design of one-dimensional heat equation with the actuators being concentrated at discrete points in the spatial domain. This systematic methodology incorporates the advanced concept of proper orthogonal decomposition for the model reduction of distributed parameter systems. After deigning a set of problem-oriented basis functions an analogous optimal control problem in the lumped domain is formulated. The optimal control problem is then solved in the time domain, in a state feedback sense, following the philosophy of adaptive critic neural networks. The control solution is then mapped back to the spatial domain using …

Cfd Simulations Of Critical Components In Fuel Filling Systems, R. Banerjee, X. Bai, D. Pugh, Kakkattukuzhy M. Isaac, D. Klein, J. Edson, W. Breig, L. Oliver

Mechanical and Aerospace Engineering Faculty Research & Creative Works

A comprehensive study is reported on the dynamics of critical components in the refueling process for passenger cars and light trucks. Nozzle, filler pipe, recirculation tube, tank, and canister are investigated. CFD simulations are conducted for flow rates of 4 liters/min (lpm) to 80 lpm for gasoline and up to 120 lpm for diesel fuel. Tank pressure, identified as a critical parameter controlling flow performance, is measured and utilized as a boundary condition. Flow simulation in a carbon canister, accomplished by treating the adsorbing carbon as a porous medium, indicates pressure drops which are in good agreement with published experimental …

An Improved Pnlms Algorithm, J. Benesty, Steven L. Grant

Electrical and Computer Engineering Faculty Research & Creative Works

The proportionate normalized least mean square (PNLMS) algorithm was developed for use in network echo cancelers. In comparison to the normalized least mean square (NLMS) algorithm, PNLMS has a very fast initial convergence and tracking when the echo path is sparse. Unfortunately, when the impulse response is dispersive, the PNLMS converges much slower than NLMS. This implies that the rule proposed in PNLMS is far from optimal. In many simulations, it seems that we fully benefit from PNLMS only when the impulse response is close to a delta function. We propose a new rule that is more reliable than the …

Estimating The Power Bus Impedance Of Printed Circuit Boards With Embedded Capacitance, Minjia Xu, Todd H. Hubing

Electrical and Computer Engineering Faculty Research & Creative Works

Embedded capacitance is an alternative to discrete decoupling capacitors and is achieved by enhancing the natural capacitance between closely spaced power and return planes. This paper employs a simple cavity model to investigate the features affecting the power bus impedance of printed circuit boards with embedded capacitance.

The Causes Of Armature Surface Fracturing Within Helical Flux-Compression Generators, Jason Baird, Paul Nicholas Worsey

Mining Engineering Faculty Research & Creative Works

Aluminum and copper tubes filled with explosive were tested during this study of high strain rate effects, as an adjunct to helical flux-compression generator research at the University of Missouri-Rolla, directly affecting the understanding of flux cutoff and high strain-rate changes in generator armatures. Longitudinal cracks characteristically developed in the outer surface of armatures at a smaller expansion ratio than predicted. These cracks occurred within two diameters of the detonator end of the armature but did not extend when the tubing expanded under explosive pressurization. Such cracks appear to cause magnetic flux cutoff, and flux losses seriously affect energy conversion …

Development Of A Program For Numerical Analysis Of Microwave Radio Links Under Different Conditions, M. Can, Sergey Kharkovsky

Electrical and Computer Engineering Faculty Research & Creative Works

Numerical analysis of system power budget is performed for radio link design and transmission planning purposes in cellular networks. The behavior of three different frequencies; 10.5 GHz, 23 GHz and 38 GHz is examined under the influence of such parameters like transmitter power output level, rain rate, fog density, distance, polarization type, antenna radius, temperature, foliage depth and etc. Received power levels are measured, calculated and reported for different radio link types and environmental conditions. A new program is developed in order to carry out system power budget analysis and design better microwave radio links. Measured and calculated values are …

Whispering-Gallery Modes In Shielded Hemispherical Dielectric Resonators, Sergey Kharkovsky, Z. E. Eremenko, V. V. Kutuzov, A. E. Kogut, Yuri F. Filipov

Electrical and Computer Engineering Faculty Research & Creative Works

The results of the numerical and experimental investigations of whispering-gallery (WG) modes in shielded hemispherical dielectric resonators are presented in this paper. It is shown that the Q factor of WG modes in the shielded resonator can be ten times much higher than the Q factor of the similar open hemispherical dielectric-resonator modes. Shielding the resonator can decrease the dimensions of both the dielectric hemisphere and resonator as a whole, saving the high-Q factor of WG modes. The usage of a cylindrical shield and local flat reflectors in the experiment provides the investigation of the high-Q factor of WG modes …

On The Interior Resonance Problem When Applying A Hybrid Fem/Mom Approach To Model Printed Circuit Boards, Yun Ji, Todd H. Hubing

Electrical and Computer Engineering Faculty Research & Creative Works

A hybrid finite element method/method of moments (FEM/MoM) technique is used to analyze a printed circuit board power bus structure where the source and observation points are in the near field. The FEM is used to model the lossy region between the planes of the board including the source. The MoM is used to model the region outside the planes and provide a radiation boundary condition to terminate the FEM mesh. Numerical results for a bridged power bus structure are compared with measurements. A nonphysical interior resonance of the electric field integral equation is observed. The problem can be avoided …

Logic Functions From Three-Terminal Quantum Resistor Networks For Electron Wave Computing, Cheng-Hsiao Wu, Diwakar Ramamurthy

Electrical and Computer Engineering Faculty Research & Creative Works

Electron transmission characteristics through a generalized three-terminal clean Aharonov-Bohm ring is investigated with an arbitrary terminal configuration. This three-terminal ring is shown to be the most basic quantum resistor network that is suitable for electron wave computing, as we demonstrate in this work. There are four basic classes of three-terminal rings. The scaling relation in each class is deduced. Thus the transmission characteristics in each class are valid from an atomic-scale-sized ring to a mesoscopic-scale-sized one, limited only by the electron phase-breaking length. The Buttiker symmetry rule is essential when searching for basic logic functions. Logic functions such as IF-THEN, …

A Quantitative Similarity Metric For Design-By-Analogy, Daniel A. Mcadams, Kristin L. Wood

Mechanical and Aerospace Engineering Faculty Research & Creative Works

During the design and development of new products, design engineers use many techniques to generate and define new and "good" concepts. Inherent in this search for solutions is the conscious and unconscious reliance on prior experience and knowledge, or design-by-analogy. In this paper, a quantitative metric for design-by-analogy is developed. This metric is based on the functional similarity of products. By using this product-similarity metric, designers are able to formalize and quantify design-by-analogy techniques during concept and layout design. The methods, as developed in this paper, allow a designer with limited experience to develop sophisticated solutions that enhance the overall …

A New Filtering Technique For A Class Of Nonlinear Systems, Ming Xin, S. N. Balakrishnan

Mechanical and Aerospace Engineering Faculty Research & Creative Works

In this paper, a new nonlinear filtering technique (θ-D filter) is presented. This filter is derived by constructing the dual of a new nonlinear regulator control technique, θ-D approximation which involves approximate solution to the Hamilton-Jacobi-Bellman equation. The structure of this filter is similar to the state dependent riccati equation filter (SDREF). However, this method does not need time-consuming online computation of the algebraic Riccati equation at each sample time compared with the SDREF. By manipulating the perturbation terms both the asymptotic stability and optimality properties can be obtained. A simple pendulum problem is investigated to demonstrate the effectiveness of …

State-Constrained Agile Missile Control With Adaptive-Critic-Based Neural Networks, Dongchen Han, S. N. Balakrishnan

Mechanical and Aerospace Engineering Faculty Research & Creative Works

In this study, we develop an adaptive-critic-based controller to steer an agile missile that has a constraint on the minimum flight Mach number from various initial Mach numbers to a given final Mach number in minimum time while completely reversing its flightpath angle. This class of bounded state space, free final time problems is very difficult to solve due to discontinuities in costates at the constraint boundaries. We use a two-neural-network structure called "adaptive critic" in this study to carry out the optimization process. This structure obtains an optimal controller through solving optimal control-related equations resulting from a Hamiltonian formulation. …

Graphite Platelet Nanostructures, Marian Mazurkiewicz

Mining Engineering Faculty Research & Creative Works

Separated graphite nanostructures are formed of thin graphite platelets having an aspect ratio of at least 1,500:1. The platelets have an angular geometric structure and may be fully independent from an original graphite particle, or partially attached to the particle. The graphite platelets have an average thickness in the range of 1-100 nm. The graphite nanostructures are created from synthetic or natural graphite using a high-pressure mill. Fluid jets of the high-pressure flaking mill cause fluid to enter the tip of cracks in the graphite particles, which creates tension at the tip. This tension causes the cracks to propagate along …

Stability Analysis Of A Dc Power Electronics Based Distribution System, Scott D. Sudhoff, Steven Pekarek, S. F. Glover, S. H. Zak, E. Zivi, J. D. Sauer, D. E. Delisle

Electrical and Computer Engineering Faculty Research & Creative Works

This paper illustrates the application of the generalized immittance space approach to the analysis of multi-bus interconnected power electronics-based power distribution system. The paper sets forth the basic classifications of power converters in regard to stability analysis, a set of network reduction transformations, and illustrates the use of these reductions in order to analyze the stability of a zonal dc distribution system. Copyright © 2002 Society of Automotive Engineers, Inc.

Counterexample Of A Claim Pertaining To The Synthesis Of A Recurrent Neural Network, Xindi Cai, Donald C. Wunsch

Electrical and Computer Engineering Faculty Research & Creative Works

Recurrent neural networks have received much attention due to their nonlinear dynamic behavior. One such type of dynamic behavior is that of setting a fixed stable state. This paper shows a counterexample to the claim of A.N. Michel et al. (IEEE Control Systems Magazine, vol. 15, pp. 52-65, Jun. 1995), that "sparse constraints on the interconnecting structure for a given neural network are usually expressed as constraints which require that pre-determined elements of T [a real n×n matrix acting on a real n-vector valued function] be zero", for the synthesis of sparsely interconnected recurrent neural networks.

Iron Phosphate Glass For The Vitrification Of Ineel Sodium Bearing Waste And Hanford Low Activity Waste, Robert Douglas Leerssen

Masters Theses

"The current study investigates the feasibility of using iron phosphate glass for the immobilization of nuclear wastes that have limited solubility in the current borosilicate glass used for vitrification. These wastes contain elements such as sulfur and phosphorus, which have proven problematic (causing phase separation at >1 wt%) for vitrification in borosilicate glasses, as well as having a high soda content (50-75 wt%) which also limits wasteloading"--Abstract, page iv.

Raman Spectroscopy Of Nanocrystalline Ceria And Zirconia Thin Films, Igor Kosacki, Vladimir Petrovsky, Harlan U. Anderson, Philippe Colomban

Materials Science and Engineering Faculty Research & Creative Works

The results of Raman-scattering studies of nanocrystalline CeO₂ and ZrO₂:16% Y (YSZ) thin films are presented. The relationship between the lattice disorder and the form of the Raman spectra is discussed and correlated with the microstructure. It is shown that the Raman line shape results from phonon confinement and spatial correlation effects and yields information about the material nonstoichiometric level.

Neodymium And Erbium Coordination Environments In Phosphate Glasses, Mevlüt Karabulut, G. K. Marasinghe, Ezzeldin Metwalli, Andrew K. Wittenauer, Richard K. Brow, C. H. Booth, D. K. Shuh

Materials Science and Engineering Faculty Research & Creative Works

The local structures of Nd3+ and Er3+ ions in two series of rare-earth (RE) phosphate glasses with nominal compositions xR203-(1-x)P2O5, where R=Nd and Er and 0.05≤x≤0.28, have been characterized by LIII-edge extended x-ray-absorption fine-structure spectroscopy (EXAFS). The RE coordination number depends on the R2O3 content, decreasing from 9.0 (10) oxygen nearest neighbors in ultraphosphate compositions (x<0.15) to 6.4 (9) oxygen nearest neighbors for the metaphosphate (x∼0.25) compositions. The average Er-O bond distance decreases from 2.29 (1) to 2.23 (1) Å, and the average Nd-O bond distance decreases from 2.40 (1) to 2.37 (1) Å over the same compositional range. The changes in coordination environments are consistent with the conversion of isolated RE polyhedra to clustered RE polyhedra sharing common oxygens as the number of available terminal oxygens per RE ion decreases with increasing x.

Interactive Virtual Laboratory For Experience With A Smart Bridge Test, Elizabeth C. Eckhoff, Vicki M. Eller, Steve Eugene Watkins, Richard Hall

Electrical and Computer Engineering Faculty Research & Creative Works

Virtual laboratory experiments can be cost effective, convenient instructional resources that have appeal to a wide range of learning styles. Expensive, time-consuming laboratory tests can be experienced repeatedly and remotely using interactive simulations and original video footage or animations. A virtual experiment can incorporate meaningful exercises, procedural options, and background hyperlinks to create a comprehensive "hands on" environment. Also, it may be used as preliminary training for the actual experiment.

An interactive LabVIEW-based laboratory for a load test simulation of an existing demonstration bridge was created. This smart truss bridge is instrumented with fiber optic strain sensors situated on the …

A New Cascaded Multilevel H-Bridge Drive, Keith Corzine, Yakov L. Familiant

Electrical and Computer Engineering Faculty Research & Creative Works

In this paper, a general structure for cascaded power converters is presented in which any number of H-bridge cells having any number of voltage levels are series connected to form an inverter phase leg. Equations are introduced for determining an optimal voltage ratio of DC voltages for the H-bridge cells which will maximize the number of voltage levels obtainable resulting in high power quality. Special cases of the generalized inverter are presented including novel 11-level and 15-level inverters. Laboratory measurements demonstrate the proposed inverter performance

Forensic Investigation Of Failed Mast Arms Of Traffic Signal Supported Structures, Genda Chen, Michael G. Barker, D. Scott Mackenzie, Christopher W. Ramsay, Joe Alderson, Lokeswarappa R. Dharani, Jiaqing Yu

Civil, Architectural and Environmental Engineering Faculty Research & Creative Works

In Missouri, 11 traffic signal mast arms fractured at the arm-post weld connection in 7 years. To reduce this fatigue failure, the Missouri Department of Transportation developed a fatigue-resistant weld profile that increases the weld leg and reduces the slope of the weld at the toe. This study investigated causes of the failed arms, compared performance of new and old weld profiles, and suggested retrofitting measures for further investigation. The scope included a metallurgical investigation of one failed field mast arm, laboratory fatigue testing of five prototype mast arms (two new and three old profiles), and laboratory failure analysis of …

A Comparative Study Of Just-In-Time (Jit) And Theory Of Constraints (Toc) Systems With Varying Constraint Locations And Operational Characteristics, Pirun Hemmondharop

Doctoral Dissertations

"Various researchers have extolled the benefits of Theory of Constraints (TOC), Just-in-Time (JIT), and other manufacturing strategies. Some supporters of JIT argue it is the least costly, while others point to the overall benefits of TOC. There are conflicting claims as to the best manufacturing philosophies which is compounded by the fact that no one system is best in every situation. The success of a production system truly depends on the manufacturing environment rather than the philosophy being used. This study uses computer simulations of differing manufacturing environments to compare Just-in-Time (JIT) and Theory of Constraints (TOC) philosophies over two …