Engineering Commons^™

Environmental Performance Analysis Of Solid Freedom Fabrication Processes, Yanchun Luo, Zhiming Ji, Ming-Chuan Leu, R. J. Caudill

Mechanical and Aerospace Engineering Faculty Research & Creative Works

This paper presents a method for analyzing the environmental performance of solid freeform fabrication (SFF) processes. In this method, each process is divided into life phases. Environmental effects of every process phase are then analyzed and evaluated based on the environmental and resource management data. These effects are combined to obtain the environmental performance of the process. The analysis of the environmental performance of SFF processes considers the characteristics of SFF technology, includes material, energy consumption, processes wastes, and disposal. Case studies for three typical SFF processes: stereolithography (SL); selective laser sintering (SLS); and fused deposition modeling (FDM) are presented …

Integrating Power Engineering Topics And Applications In Non-Power Courses, S. Legowski, Badrul H. Chowdhury, J. J. Cupal, R. G. Jacquot, B. J. W. Pierre, A. H. M. S. Ula, B. M. Wilamowski

Electrical and Computer Engineering Faculty Research & Creative Works

This paper investigates integrating power engineering material over the breadth of an electrical engineering curriculum. Electrical engineering curricula have a large number of required courses and many subareas for students to study. By introducing power concepts in a variety of courses, students may be motivated to take additional courses in the power area and are better prepared for the diverse background which will be required of them as practising power engineers. The important interrelationships between subareas of electrical engineering are better understood by students when cross discipline applications are discussed. This paper describes the introduction of power concepts and applications …

Displacement-Based Analysis And Design Of Rigid Retaining Walls During Earthquakes, Yingwei Wu

Doctoral Dissertations

"This research focused on the analysis and design of rigid retaining walls subjected to earthquakes and considered nonlinear foundation soil properties. The simultaneous sliding and rocking movements of retaining walls were considered. Seven field conditions, including moist, submerged, perched and saturated backfill with a sloping drain, were specified by design codes. A computer program capable of computing displacement using real time history records or equivalent sinusoidal motions was developed. Finally, a dynamic design procedure was proposed for practicing engineers.

The study revealed that maximum shear modulus in foundation soil, maximum ground acceleration, and soil nonlinearity had significant effect on the …

Machine Tool Accuracy Characterization, Error Modeling And Compensation Using Telescopic Ballbar And Laser Interferometer, Yalcin M. Ertekin

Doctoral Dissertations

"This dissertation presents the results of the research investigation on the machine tool accuracy characterization, error modeling and error compensation using telescopic ballbar and laser interferometer. Increasing demand for both higher machine tool accuracy and machining tolerances has resulted in a great need to measure and characterize the accuracy of NC machine tools and minimize machine tool induced errors on machined components before manufacturing parts, instead of inferring it from parts already machined. Using a telescopic magnetic ballbar, the results of the accuracy assessment of an old Bridgeport Series I CNC 2 1/2 axes vertical machining center are presented in …

Influence Of Chemical Reactions In Magnesia-Graphite Refractories: Ii, Effects Of Aluminum And Graphite Contents In Generic Products, Carmen Baudín, Carlos Alvarez, Robert E. Moore

Materials Science and Engineering Faculty Research & Creative Works

A group of magnesia-graphite and magnesia-graphite-aluminum materials, the compositions of which represent a wide range of graphite contents (approximately 10-16.4 wt.%), aluminum contents (0-5.2 wt.%), and MgO and graphite qualities, were fabricated, using standard commercial practices. Chemical analysis and determination of room-temperature modulus of rupture (MOR) and Young's modulus, as well as a complete microstructural characterization of the as-received materials, were performed. Mechanical characterization at high temperature (1000°, 1200°, and 1450 °C) was done in terms of Young's modulus and MOR in an argon atmosphere (°C). Modulus-of-elasticity values ranged from 4 to 16 GPa, and their evolution with temperature was …

Structural Disorder And The Origin Of High-Tc Suppression In La₁.₈₇₅Ba₀.₁₂₅ Cuo4−Δ, Daniel Haskel, Edward A. Stern, Fatih Dogan, Arnie R. Moodenbaugh

Materials Science and Engineering Faculty Research & Creative Works

Polarized x-ray absorption fine structure (XAFS) measurements at all La, Ba and Cu sites were used to study local structural features that accompany the strong Tc suppression at: r,,, 1/8 in La₂BaCuO₄. Two critical parameters regulating the strength of hole-lattice coupling in this material were determined, ie, the direction and magnitude of CuO₆ octahedra local tilts. Our findings include the existence of large disorder in the magnitude of the tilt angle about its average value (0), with an rms~~ 2 (0). We suggest that this large disorder strongly scatters a large fraction of states at …

Analog Hardware Implementation Of Continuous-Time Adaptive Filter Structures, John G. Harris, Jui Kuo Juan, Jose C. Principe

Electrical and Computer Engineering Faculty Research & Creative Works

We have implemented a four-tap adaptive filter in a continuous-time analog VLSI circuit. Since an ideal delay is impossible to implement in continuous-time hardware, we implemented the delay line as a cascade of low-pass filters (called the gamma filter). Since many years of research in our lab has shown that the gamma filter outperforms the ideal delay line for a wide range of applications, the gamma filter should not be considered merely a crude approximation of the ideal delay line. We show measured results from an analog chip that solves the problem of system identification-identifying an unknown linear circuit from …

In-Clip Search Algorithm For Content-Based Audio Retrieval, Punpiti Piamsa-Nga, Nikitas A. Alexandridis, Sanan Srakaew, George C. Blankenship, S. R. Subramanya

Electrical and Computer Engineering Faculty Research & Creative Works

Researchers are currently more interested in searching for fragments that are similar to a query, than a total data item that is similar to a query; the search interest is for "contains", not "is". The paper presents an O(logn) algorithm, called the "generalized virtual node (GVN)" algorithm; the GVN algorithm is a search algorithm for data fragments that have similar contents to that of a query. An example of the use of the GVN algorithm is in the search of a database of audio recordings for a few measures of a melody. Each audio clip is transformed into characteristic features …

A Distributed Algorithm For The Classification Of Images On A Network Of Workstations, S. R. Subramanya

Electrical and Computer Engineering Faculty Research & Creative Works

Image databases require content-based queries and retrievals. Fast and accurate retrievals for user queries depend on efficient indexing and searching schemes. The classification of images into different categories (classes) is an important task which facilitates the indexing and searching process. The classification of huge amounts of image data place enormous demands on computational requirements. Network of workstations (NOWs, also sometimes called clusters) are a cost-effective way of providing the much-needed computational power in such applications. This paper presents a distributed scheme for the classification of images in an image database, using a network of workstations. The results of the classification …

Use Of Transforms For Indexing In Audio Databases, S. R. Subramanya, Abdou Youssef, Bhagirath Narahari, Rahul Simha

Electrical and Computer Engineering Faculty Research & Creative Works

The phenomenal increases in the amounts of audio data being generated, processed and used in several computer applications have necessitated the development of audio database systems with newer features, such as content-based queries and similarity searches, to manage and use such data. Fast and accurate retrieval for content-based queries is crucial in order for such systems to be useful. Efficient content-based indexing and similarity searching schemes are keys to providing fast and relevant data retrieval. This paper studies and evaluates the different parameters involved in an indexing scheme which uses transforms (as used in signal processing) for generating the audio …

Hypersonic Drag And Heat Transfer Reduction Using A Forward Facing Jet, Benjamin Meyer, Harlan F. Nelson, David W. Riggins

Mechanical and Aerospace Engineering Faculty Research & Creative Works

A two-dimensional numerical study of the effects of a forward-facing jet located at the stagnation point of a blunt body on wave drag, heat transfer, and skin friction drag is presented for Mach 6.5 flow at 30 km altitude. The full Navier-Stokes equations are used with variable viscosity and thermal conductivity. It is shown that upstream injection can significantly modify the flow field. If the jet conditions are chosen properly, large reductions in drag and heat transfer can be obtained resulting in possible increases in the volumetric efficiency and static stability of aircraft and reductions in heating protection requirements for …

A New Reflection Free Boundary In Uniform Flow Using Mapped Infinite Wave Envelope Elements, Walter Eversman, Indranil Danda Roy

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Variable order mapped infinite wave envelope elements are developed for finite element modeling of acoustic radiation in a uniformly moving medium. These elements can be used outside of the near field as a non-reflecting boundary condition for computations on an infinite domain in which a radiating body is immersed in a moving medium. Mapped infinite wave envelope elements provide a boundary condition equivalent to stiffness, mass, and damping matrices appended to the inner mesh. A demonstration of the characteristics of the mapped infinite wave envelope elements is given in the context of acoustic radiation from a turbofan inlet for which …

Value-Based Product Structure Evaluation For Disassembly, Shivakumar Viswanathan, Venkat Allada

Engineering Management and Systems Engineering Faculty Research & Creative Works

Designing for the ease of end of life (EOL) disassembly is an important design function. The product structure that is the spatial relationships between the parts of the product and the value distribution over them plays an important role in determining the ease and profitability of disassembly. This paper presents a conceptual methodology to determine the effect of the spatial precedence on the desired value precedence of the product. The methodology introduces a digraph called the bureau graph to model this relationship between the spatial and value precedence structures. Based on this modeling indices are derived that provide a holistic …

Reproduction Of Spectrum Envelope Of Microwave Wideband Noise And Detection A Narrowband Signal In It, Marina Koledintseva, Alexander A. Kitaytsev, V. A. Konkin

Electrical and Computer Engineering Faculty Research & Creative Works

A method of adequate visual microwave wide-band intense noise envelope reproduction in wide frequency range (several octaves), power parameters measurement and detection of a narrow-band signal with unknown frequency and power against a background of noise is presented. It is based on application of nonheterodyne gyromagnetic converter, operating in two regimes: resonance detection and cross-multiplication. Operation of the two-channel measurer of spectrum power density combining the mentioned functions is discussed

Speaker Identification Using A Combination Of Different Parameters As Feature Inputs To An Artificial Neural Network Classifier, Viresh Moonasar, Ganesh K. Venayagamoorthy

Electrical and Computer Engineering Faculty Research & Creative Works

This paper presents a technique using artificial neural networks (ANNs) for speaker identification that results in a better success rate compared to other techniques. The technique used in this paper uses both power spectral densities (PSDs) and linear prediction coefficients (LPCs) as feature inputs to a self organizing feature map to achieve a better identification performance. Results for speaker identification with different methods are presented and compared.

A Continually Online Trained Artificial Neural Network Identifier For A Turbogenerator, Ganesh K. Venayagamoorthy, Ronald G. Harley

Electrical and Computer Engineering Faculty Research & Creative Works

The increasing complexity of modern power systems highlights the need for advanced modelling techniques for effective control of power systems. This paper presents results of simulation and practical studies carried out on identifying the dynamics of a single turbogenerator connected to an infinite bus through a short transmission line, using a continually online trained (COT) artificial neural network (ANN).

A Robust Artificial Neural Network Controller For A Turbogenerator When Line Configuration Changes, Ganesh K. Venayagamoorthy, Ronald G. Harley

Electrical and Computer Engineering Faculty Research & Creative Works

This paper presents the design of a robust controller for a turbogenerator. The robust controller is an artificial neural network (ANN) that is trained offline on a family of ANN models of the turbogenerator. This ANN controller augments/replaces the traditional automatic voltage controller (AVR) and the turbine governor of the generator. Simulation results are presented to show that the ANN controller is robust when the transmission line configuration changes.

Application Of Composite Gyromagnetic Materials For Absorbing Radiation Produced By Microwave Oven, Marina Koledintseva, Alexander A. Kitaytsev, V. A. Konkin, V. P. Cheparin, Andrey A. Shinkov

Electrical and Computer Engineering Faculty Research & Creative Works

Composite gyromagnetic radioabsorbing material (RAM) on the basis of polycrystalline hexagonal ferrites is elaborated for the suppression of unwanted radiation produced by microwave ovens (MWO). Results of laboratory investigation of this material application in the MWO having a magnetron source of microwave radiation are represented.

Performance Characteristics Of A Cascaded Two-Level Converter, Keith Corzine, C. A. Whitcomb, S. D. Sudhoff

Electrical and Computer Engineering Faculty Research & Creative Works

A cascaded two-level power converter is proposed which utilizes two six-transistor inverters and is capable of producing voltages which are identical to those of three-level and four-level converters. Since the machine voltages are the same, the converter performance is the same as is verified through laboratory tests. The advantages and disadvantages of the proposed cascaded converter are explored. The proposed converter is simpler to construct and offers more nonredundant switching states per number of active semiconductors than standard multi-level converters

Liquid Holdup Measurement Techniques In Laboratory High Pressure Trickle Bed Reactors, Muthanna H. Al-Dahhan, Wes Highfill

Chemical and Biochemical Engineering Faculty Research & Creative Works

Three Different Techniques, Which Are Tracer, Drainage and Weighing Methods, Are Used to Measure Liquid Holdup in a Laboratory Trickle-Bed Reactor Operated under High Pressure. the Holdup Measurements Are Compared to Determine the Applicability of These Methods at High Pressure Operation. It Was Found that Tracer and Drainage Techniques Give Comparable Values for the Total Liquid Holdup. Although Several Investigators Recommended the Weighing Method over the Others based on their Experiments Performed at Atmospheric Conditions, It Was Found that the Weighing Method Failed to Measure Liquid Holdup Properly at High Pressure Operation.

Mechanism Of Interaction Of Asphalt Cement With Crumb Rubber Modifier, Magdy Abdelrahman, Samuel Carpenter

Civil, Architectural and Environmental Engineering Faculty Research & Creative Works

The nature of the interaction process between asphalt cement and crumb rubber modifier (CRM) has not been fully understood. Two main types of mechanisms that affect the produced binder properties are reported: particle swelling and degradation (devulcanization and depolymerization). These mechanisms occur as the binder is subjected to different combinations of interaction time and temperature. Insight into the mechanisms by which the interaction between the two materials takes place through monitoring the changes in the rheological parameters of the binder is provided. The effects of the interaction process variables, time and temperature, are explained. The effect of CRM properties, including …

Predicting The Unconfined Compressive Strength Of The Breathitt Shale Using Slake Durability, Shore Hardness And Rock Structural Properties, Engin C. Koncagül, Paul M. Santi

Geosciences and Geological and Petroleum Engineering Faculty Research & Creative Works

Compressive strength is the most widely used design parameter in the construction industry and in rock engineering. For example, Bieniawski [Bieniawski, Z.T., Estimating the strength of rock materials, Is. J. S. Afr. Inst. Min. Metall., 1974, 74, 312-320.] reported that mining engineers request the uniaxial compressive strength (UCS) more often than any other rock property. However, standards set for specimen preparation are very demanding. Therefore, it is quite difficult and sometimes impossible to fulfill these requirements using weak rocks and especially shales. This paper evaluates the use of the slake durability and Shore hardness tests to estimate UCS, based on …

Remedy Selection For Cleanup Of Uncontrolled Waste Sites, Paul D. Bennett, Brad Brumbach, Tyrone W. Farmer, Preston L. Funkhouser Iv, Allen W. Hatheway

Geosciences and Geological and Petroleum Engineering Faculty Research & Creative Works

Selection of remedy for uncontrolled hazardous waste sites involves comparisons of various technological approaches for minimization of threats and achievement of cleanup action levels. Approaches specified in the Comprehensive Environmental Response, Compensation and Liability Act (SUPERFUND Law) National Contingency Plan (40 CFR 300) are broadly labeled as actions, alternatives, and technologies. We have found considerable perplexity in denoting the rank-hierarchy of these approaches and have developed a classification system for dealing with the totality of available measures for consideration in selection of remedy.

Optimized Calibration For Unsteady Flow Modeling Using A Genetic Algorithm, Daniel Sanchez, Jerome A. Westphal

Civil, Architectural and Environmental Engineering Faculty Research & Creative Works

The calibration of an unsteady flow model generally relies on the estimation of roughness coefficients, which act as descriptors of friction resistance along the channel. Here an optimized procedure is implemented by incorporating a genetic algorithm (GA) to automate the process. This approach is suitable because discrete parameters are considered. The target is a one-dimensional unsteady flow model in which the roughness coefficient is allowed to vary not only along the river axis, but also dynamically with discharge. The objective function is the root mean square of the difference between measured and computed water levels at a given cross section. …

Stage-Discharge Relations On The Middle Mississippi River, Jerome A. Westphal, D. B. Thompson, Glendon Taylor Stevens, C. N. Strauser

Civil, Architectural and Environmental Engineering Faculty Research & Creative Works

Based on measurements made on the Middle Mississippi River during the 1993 flood, stage-discharge relations for the rating curve are not single-valued. Analyses of these data suggest that the range of flow rates at a given stage is larger than that attributable to measurement replication error alone. Patterns of stage-discharge measurements also imply a tendency toward hysteresis. However, neither changes in stage nor changes in flow rate correlate with short-term scour and fill at gauging sites.

Liquefaction Of Silts And Silt-Clay Mixtures, Tianqiang Guo, Shamsher Prakash

Civil, Architectural and Environmental Engineering Faculty Research & Creative Works

Low plasticity silts and silty clays occur extensively in the central United States. For evaluating their liquefaction potential during an earthquake, no guidelines are available based on their density, void ratio, plasticity index, standard penetration values, or any other simple soil property. Their liquefaction behavior is not properly understood at present and is often confused with that of sand-silt mixtures. Pore water pressures and liquefaction in silt and silt-clay mixtures are discussed, and the influences of plasticity index on their cyclic strength are reviewed critically. It is concluded that considerable additional work is needed to fully understand the liquefaction behavior …

Efficient Training Techniques For Classification With Vast Input Space, Donald C. Wunsch, Emad W. Saad, J. J. Choi, J. L. Vian

Electrical and Computer Engineering Faculty Research & Creative Works

Strategies to efficiently train a neural network for an aerospace problem with a large multidimensional input space are developed and demonstrated. The neural network provides classification for over 100,000,000 data points. A query-based strategy is used that initiates training using a small input set, and then augments the set in multiple stages to include important data around the network decision boundary. Neural network inversion and oracle query are used to generate the additional data, jitter is added to the query data to improve the results, and an extended Kalman filter algorithm is used for training. A causality index is discussed …

Integrated Manufacturing System For Precision Press Tooling, S. Chaturvedi, Venkat Allada

Engineering Management and Systems Engineering Faculty Research & Creative Works

The press tooling industry, characterized by many small-scale job-shops, is facing an increasingly competitive global market. This comes at a time when there is a shortage of experienced process planners and unavailability of affordable CAD/CAM systems that could provide an integrated solution for manufacturing sheet metal tooling. Many commercially available CAD/CAM systems are either too expensive or too narrow in scope, in the sense that they provide only point solutions. The design of press tools and its manufacturing functions are highly specialized and knowledge-intensive in nature. This paper presents a framework and the implementation details of an integrated system that …

Experimental Studies With A Continually Online Trained Artificial Neural Network Controller For A Turbogenerator, Ganesh K. Venayagamoorthy, Ronald G. Harley

Electrical and Computer Engineering Faculty Research & Creative Works

This paper presents the design of a continually online trained (COT) artificial neural network (ANN) controller for a laboratory turbogenerator system connected to the infinite bus through a transmission line in real time. Two COT ANNs are used for the implementation: one ANN to identify the complex nonlinear dynamics of the power system, and the other ANN to control the turbogenerator. Practical results are presented to show that COT ANN controllers can control turbogenerators under steady state as well as transient conditions in the laboratory environment

Implementation Of An Adaptive Neural Network Identifier For Effective Control Of Turbogenerators, Ganesh K. Venayagamoorthy, Ronald G. Harley

Electrical and Computer Engineering Faculty Research & Creative Works

This paper describes an on-line identification technique for modelling a turbogenerator system. The dynamics of a single turbogenerator infinite bus system are modelled using an adaptive artificial neural network identifier (AANNI) based on continual online training (COT). This paper goes further to show that multilayered perceptrons with deviation signals as inputs and outputs trained using the standard backpropagation algorithm retain past learned information despite COT. Simulation and practical results are presented.