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Articles 1591 - 1620 of 2079

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Fluid-Structure Interaction In Taylor-Couette Flow, Martin Horst Willi Kempf Jan 1998

Fluid-Structure Interaction In Taylor-Couette Flow, Martin Horst Willi Kempf

Doctoral Dissertations

The linear stability of a viscous fluid between two concentric, rotating cylinders is considered. The inner cylinder is a rigid boundary and the outer cylinder has an elastic layer exposed to the fluid. The subject is motivated by flow between two adjoining rollers in a printing press. The governing equations of the fluid layer are the incompressible Navier-Stokes equations, and the governing equations of the elastic layer are Navier's equations. A narrow gap, neutral stability, and axisymmetric disturbances are assumed. The solution involves a novel technique for treating two layer stability problems, where an exact solution in the elastic layer …

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A Very High Level Logic Synthesis, Norbert Ange Valverde Jan 1998

A Very High Level Logic Synthesis, Norbert Ange Valverde

Doctoral Dissertations

The evolution of Computer Aided Design (CAD) calls for the incorporation of design specifications into a microelectronics system development cycle. This expansion requires the establishment of a new generation of CAD procedures, defined as Very High Level Logic Synthesis (VHLLS). The fundamental characteristics of open-ended VHLLS are: (1) front-end graphical interface; (2) time encapsulation; and (3) automatic translation into a behavioral description. Consequently, the VHLLS paradigm represents an advanced category of CAD-based microelectronics system design, built on a deep usage of expert systems and intelligent methods. Artificial Intelligence (AI) formalisms such as Knowledge Representation System (KRS) are necessary to model …

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Numerical Modeling Of Multi-Species Transport In Soils Under Electric Fields., Wenbing Zheng Jan 1998

Numerical Modeling Of Multi-Species Transport In Soils Under Electric Fields., Wenbing Zheng

LSU Historical Dissertations and Theses

A generalized mathematical model for electrokinetic soil processing is presented for multi-species transport of reactive components under electric fields in two-dimensional geometry, based on the earlier Acar-Alshawabkeh model. In this model, sets of partial differential equations are formulated for the transport of fluid, charge, and species in a saturated soil under coupled hydraulic, electrical, and chemical potentials. Chemical reactions pertaining to sorption, precipitation/dissolution, aqueous phase equilibria, water autoionization, and electrolysis are included in the new model. The boundary conditions corresponding to the mass transport equations are described. A program, EK-SIM (ElectroKinetic Soil Processing SIMulation), has been developed to simulate electrokinetic …

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Stability And Weight Smoothing In Cmac Neural Networks, David Paul Campagna Jan 1998

Stability And Weight Smoothing In Cmac Neural Networks, David Paul Campagna

Doctoral Dissertations

Although the CMAC (Cerebellar Model Articulation Controller) neural network has been successfully used in control systems for many years, its property of local generalization, the availability of trained information for network responses at adjacent untrained locations, although responsible for the networks rapid learning and efficient implementation, results in network responses that is, when trained with sparse or widely spaced training data, spiky in nature even when the underlying function being learned is quite smooth. Since the derivative of such a network response can vary widely, the CMAC's usefulness for solving optimization problems as well as for certain other control system …

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Modeling And Optimal Design Of Spiral-Wound Membrane Systems For Gas Separations., Runhong Qi Jan 1998

Modeling And Optimal Design Of Spiral-Wound Membrane Systems For Gas Separations., Runhong Qi

LSU Historical Dissertations and Theses

Membrane system economics can be significantly affected by process modeling and design. Available spiral-wound permeator models are difficult to use for process design because of their mathematical complexity and high computational demands. Existing sequential design methods yield suboptimal flowsheets when multiple permeation stages are required. In this dissertation, more effective modeling and design techniques for spiral-wound systems separating binary and multicomponent gas mixtures are developed. An approximate modeling approach based on the assumption that the residue flow rate is constant in the direction of bulk permeate flow is proposed. This assumption allows a significant simplification of basic transport models which …

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Bioremediation Of Petroleum Hydrocarbons In Louisiana's Saltwater Marshes: Sediment Oxygen Demand Model., Won Sik Shin Jan 1998

Bioremediation Of Petroleum Hydrocarbons In Louisiana's Saltwater Marshes: Sediment Oxygen Demand Model., Won Sik Shin

LSU Historical Dissertations and Theses

Laboratory core studies were conducted to determine sediment oxygen demand (SOD) in petroleum hydrocarbon contaminated salt marshes. Natural degradation processes in salt marshes such as aerobic respiration, nitrification and sulfate reduction were investigated to quantify SOD. Oxygen demand in oiled/fertilized cores was greater than control and fertilized cores due to increased oxygen consumption by oil degradation and oxidation of reduced chemicals; sulfide and ammonium. SOD under non-flooded condition was greater than flooded condition due to an increased area of oxic-anoxic interface during air exposure. This may indicate that significant biodegradation of crude oil only occurs when the surface of the …

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Characterization And Analysis Of The Superabrasive Diamond Blade Sawing Process., Harlan Dwayne Jerro Jan 1998

Characterization And Analysis Of The Superabrasive Diamond Blade Sawing Process., Harlan Dwayne Jerro

LSU Historical Dissertations and Theses

Diamond-impregnated segmented circular blade sawing is one of the most effective, versatile, and extensively used methods of processing rock and other hard materials, such as granite, marble, concrete and asphalt. For many years, it has been known that chip thickness is one of the most significant parameters in the understanding of the sawing process, and other variables such as force and power have been correlated with it. In this work, the material chipping geometries have been mathematically defined and derived through kinematics analysis. From these chipping geometries, chip area and thickness relations have been obtained. A relation for the mean …

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Multiobjective Optimal Filtering And Control., Xiang Chen Jan 1998

Multiobjective Optimal Filtering And Control., Xiang Chen

LSU Historical Dissertations and Theses

A fundamental question in feedback control design is how to achieve desired performance under system uncertainties and external disturbances. The well-known LQG and ${\cal H}\sb2$ control design techniques are well suited for achieving some well-defined optimal transient performance under certain classes of stochastic external disturbances such as white noise. However, these optimal control design techniques are highly model dependent and may be very sensitive to parameter variations and system uncertainties. The ${\cal H}\sb{\infty}$ control theory, on the other hand, was developed precisely because of the desire to overcome these deficiencies. One potential shortfall of the existing ${\cal H}\sb{\infty}$ control design …

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A Knowledge-Based System For Reliability-Centered Maintenance In The Chemical Industry., Daniel Jesus Fonseca Jan 1998

A Knowledge-Based System For Reliability-Centered Maintenance In The Chemical Industry., Daniel Jesus Fonseca

LSU Historical Dissertations and Theses

An innovative new framework for the implementation of reliability centered maintenance (RCM) in industrial settings was developed and implemented during this study. Fuzzy reasoning algorithms were designed to evaluate and assess the likelihood of equipment failure mode precipitation and aggravation. Furthermore, an alternative to the traditional RCM decision tree for prioritizing equipment failure modes was defined through the development of an approximate reasoning scheme. This priority scheme not only takes into account the relevancy of failure modes on local and product effects, but also their possibility of occurrence, as well as associated negative consequences on adjacent machinery. The new RCM …

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Analysis Of Taper-Taper Adhesive-Bonded Joints In Composite Plates Under Tension And Cylindrical Bending., Jack Elwin Helms Jr Jan 1998

Analysis Of Taper-Taper Adhesive-Bonded Joints In Composite Plates Under Tension And Cylindrical Bending., Jack Elwin Helms Jr

LSU Historical Dissertations and Theses

A taper-taper adhesive-bonded joint between two composite plates has been analyzed under tension and cylindrical bending. Two tension models were derived. The first model was based on mechanics of materials and the second model used laminated plate theory and shear correction factors. For the mechanics of materials model the condition of plane strain was assumed for the adherends and adhesive. Average stresses were used in the adherends and point-wise stresses were used in the adhesive. The model derived consisted of four second-order ordinary differential equations with variable coefficients. The adherends were characterized by the extensional Young's modulus. The equations were …

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Experimental And Theoretical Study Of Dynamic Water Control In Oil Wells., Ephim I. Shirman Jan 1998

Experimental And Theoretical Study Of Dynamic Water Control In Oil Wells., Ephim I. Shirman

LSU Historical Dissertations and Theses

A dynamic water control, dubbed Downhole Water Sink (DWS) technology, is a well completion technique for production of hydrocarbons from reservoirs with bottom aquifer causing water coning. Typically, a DWS well is dually completed with top completion designated mostly for hydrocarbon production and bottom completion used for water drainage and coning control. Positions and flow rates of the completions are the DWS performance parameters to be determined by a process designer. This dissertation presents a theoretical and experimental study of DWS performance for various reservoir conditions and production schedules. A new mathematical model, developed in this work calculates steady state …

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Development Of A New Methodology For Particle Transport Calculations Utilizing Pointwise-Continuous Nuclear Data., Mehdi Asgari Jan 1998

Development Of A New Methodology For Particle Transport Calculations Utilizing Pointwise-Continuous Nuclear Data., Mehdi Asgari

LSU Historical Dissertations and Theses

The purpose of this study is to develop a new method to compute a continuous-energy representation of the neutron flux spectrum using the one-dimensional discrete ordinates method. The technique provides a rigorous calculational tool for applications that require a detailed description of the fine-structure variation in the space-dependent neutron energy spectrum over some energy ranges. This technique uses the combination of multigroup (MG) and rigorous pointwise (PW) solutions to the steady state Boltzmann transport equation in the calculations. Also utilized in this methodology are two new methods called "sub-moment" expansion and "cumulative integral" operator to accurately evaluate the Legendre moments …

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Thermomechanical Characterization Of Heat-Activated Coupling For Advanced Composite Piping Systems., Patrick Fitzgerald Mensah Jan 1998

Thermomechanical Characterization Of Heat-Activated Coupling For Advanced Composite Piping Systems., Patrick Fitzgerald Mensah

LSU Historical Dissertations and Theses

A new technology for joining advanced composite piping systems, based on heat-activated coupling (HAC) of a thermosetting pre-impregnated (prepreg) fiber reinforced material has been advanced. The successful design of a heat-activated coupled joint depends on achieving the following requirements: (1) uniformly cured prepreg bonded to the surfaces of coupled pipe; and (2) minimal residual thermal stress as a result of the curing process. In order to address the above concerns, thermal characterization of the uncured and cured prepreg used was undertaken in order to establish prerequisite chemical kinetics parameters and material property data required for the curing process models and …

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Pseudo Power Signatures For Nonstationary Signal Analysis And Classification., Vidya Venkatachalam Jan 1998

Pseudo Power Signatures For Nonstationary Signal Analysis And Classification., Vidya Venkatachalam

LSU Historical Dissertations and Theses

This research focuses on the analysis and classification of multicomponent non-stationary signals of arbitrary duration. The proposed classification approach has potential applications in areas like moving target detection, object recognition, oil exploration, and speech processing. The wavelet transform is used as the basis for the analysis. The classification technique is based on novel scale energy density functions, called pseudo power signatures , which are independent of signal length, and which can be used to characterize the time-scale energy distribution of the signal. These signatures allow for fast classification of signals regardless of their length. Two approaches to determine pseudo power …

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Stress And Strength Of Laminated Composite Containing A Circular Hole., Yi Zhao Jan 1998

Stress And Strength Of Laminated Composite Containing A Circular Hole., Yi Zhao

LSU Historical Dissertations and Theses

This dissertation is to study the stress and strength of a finite laminated plate containing a circular hole subjected to tension. Efforts were made in three aspects: theoretical modeling, computer simulation using finite element method, and experimental evaluation using unidirectional and crossply Scotchply laminates. The stress concentration factor, normal stress distribution and tensile strength of laminates with various hole sizes and gage lengths were investigated. Theoretically, two models were proposed to describe the normal stress distribution of a laminate with finite width and finite length. By defining a width correction function and a size correction function, the normal stress in …

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Bs News Jan 1998

Bs News

Building Services Engineering

No abstract provided.

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Wright State University College Of Engineering And Computer Science Bits And Pcs Newsletter, Volume 13, Number 10, December 1997, College Of Engineering And Computer Science, Wright State University Dec 1997

Wright State University College Of Engineering And Computer Science Bits And Pcs Newsletter, Volume 13, Number 10, December 1997, College Of Engineering And Computer Science, Wright State University

BITs and PCs Newsletter

A twelve page newsletter created by the Wright State University College of Engineering and Computer Science that addresses the current affairs of the college.

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Wright State University College Of Engineering And Computer Science Bits And Pcs Newsletter, Volume 13, Number 9, November 1997, College Of Engineering And Computer Science, Wright State University Nov 1997

Wright State University College Of Engineering And Computer Science Bits And Pcs Newsletter, Volume 13, Number 9, November 1997, College Of Engineering And Computer Science, Wright State University

BITs and PCs Newsletter

A twelve page newsletter created by the Wright State University College of Engineering and Computer Science that addresses the current affairs of the college.

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Wright State University College Of Engineering And Computer Science Bits And Pcs Newsletter, Volume 13, Number 8, October 1997, College Of Engineering And Computer Science, Wright State University Oct 1997

Wright State University College Of Engineering And Computer Science Bits And Pcs Newsletter, Volume 13, Number 8, October 1997, College Of Engineering And Computer Science, Wright State University

BITs and PCs Newsletter

A twelve page newsletter created by the Wright State University College of Engineering and Computer Science that addresses the current affairs of the college.

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Wright State University College Of Engineering And Computer Science Bits And Pcs Newsletter, Volume 13, Number 7, September 1997, College Of Engineering And Computer Science, Wright State University Sep 1997

Wright State University College Of Engineering And Computer Science Bits And Pcs Newsletter, Volume 13, Number 7, September 1997, College Of Engineering And Computer Science, Wright State University

BITs and PCs Newsletter

A ten page newsletter created by the Wright State University College of Engineering and Computer Science that addresses the current affairs of the college.

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Wright State University College Of Engineering And Computer Science Bits And Pcs Newsletter, Volume 13, Number 6, June 1997, College Of Engineering And Computer Science, Wright State University Jun 1997

Wright State University College Of Engineering And Computer Science Bits And Pcs Newsletter, Volume 13, Number 6, June 1997, College Of Engineering And Computer Science, Wright State University

BITs and PCs Newsletter

Wright State University College of Engineering and Computer Science

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Wright State University College Of Engineering And Computer Science Bits And Pcs Newsletter, Volume 13, Number 5, May 1997, College Of Engineering And Computer Science, Wright State University May 1997

Wright State University College Of Engineering And Computer Science Bits And Pcs Newsletter, Volume 13, Number 5, May 1997, College Of Engineering And Computer Science, Wright State University

BITs and PCs Newsletter

A twelve page newsletter created by the Wright State University College of Engineering and Computer Science that addresses the current affairs of the college.

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Wright State University College Of Engineering And Computer Science Bits And Pcs Newsletter, Volume 13, Number 4, April 1997, College Of Engineering And Computer Science, Wright State University Apr 1997

Wright State University College Of Engineering And Computer Science Bits And Pcs Newsletter, Volume 13, Number 4, April 1997, College Of Engineering And Computer Science, Wright State University

BITs and PCs Newsletter

A ten page newsletter created by the Wright State University College of Engineering and Computer Science that addresses the current affairs of the college.

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Bs News Apr 1997

Bs News

Building Services Engineering

No abstract provided.

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Wright State University College Of Engineering And Computer Science Bits And Pcs Newsletter, Volume 13, Number 3, March 1997, College Of Engineering And Computer Science, Wright State University Mar 1997

Wright State University College Of Engineering And Computer Science Bits And Pcs Newsletter, Volume 13, Number 3, March 1997, College Of Engineering And Computer Science, Wright State University

BITs and PCs Newsletter

A ten page newsletter created by the Wright State University College of Engineering and Computer Science that addresses the current affairs of the college.

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Guide To Ms018 Stone & Webster, Inc. Records, Lisa M. Borden Mar 1997

Guide To Ms018 Stone & Webster, Inc. Records, Lisa M. Borden

Finding Aids

Engineering contractors Stone & Webster, Inc. of Boston, Massachusetts, working in conjunction with the El Paso Electric Railway Company, replaced the old International Bridge on Stanton Street between Ciudad Juárez, Mexico and El Paso, Texas with a new structure of reinforced concrete in 1924. The existing wooden bridge, built in 1902, was no longer adequate to support the increased amount of traffic, including the electric trolley cars in use at that time. Mexico contributed the engineering plus the concrete used in the pilings, while the financing for the actual construction was supplied by the United States. The bridge was replaced …

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Wright State University College Of Engineering And Computer Science Bits And Pcs Newsletter, Volume 13, Number 2, February 1997, College Of Engineering And Computer Science, Wright State University Feb 1997

Wright State University College Of Engineering And Computer Science Bits And Pcs Newsletter, Volume 13, Number 2, February 1997, College Of Engineering And Computer Science, Wright State University

BITs and PCs Newsletter

A twelve page newsletter created by the Wright State University College of Engineering and Computer Science that addresses the current affairs of the college.

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Dynamic Response Of Poroelastic Materials Containing Bingham Fluid: Application To Electrorheological Fluids, Mete Kesan Jan 1997

Dynamic Response Of Poroelastic Materials Containing Bingham Fluid: Application To Electrorheological Fluids, Mete Kesan

Doctoral Dissertations

This work examines the dynamic response to harmonic loading of a disk of poroelastic material containing non-Newtonian Bingham fluid which exhibits a yield stress. Biot's poroelasticity equations and modified Darcy's law for non-Newtonian fluids exhibiting a yield stress are combined together to obtain the governing equations of the system for quasi-static case. Dissipation due to friction arising from the flow of fluid relative to the solid is taken into account but inertia effects are neglected. The response and the complex modulus of the system are calculated using the finite element method taking into account the nonlinear nature of Bingham fluid. …

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A Sensory-Based Adaptive Walking Control Algorithm For Variable Speed Biped Robot Gaits, Andrew L. Kun Jan 1997

A Sensory-Based Adaptive Walking Control Algorithm For Variable Speed Biped Robot Gaits, Andrew L. Kun

Doctoral Dissertations

A balance scheme for handling variable speed gaits was implemented on an experimental biped. The control scheme used pre-planned but adaptive motion sequences in combination with closed loop reactive control. CMAC neural networks were responsible for the adaptive control of side-to-side and front-to-back balance. The biped performance improved with neural network training. The biped was able to walk with variable speed gaits, and to change gait speeds on the fly. The slower gait speeds required statically balanced walking, while the faster speeds required dynamically balanced walking. It was not necessary to distinguish between the two balance modes within the controller. …

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Modeling Of The Electromagnetic Radiation From Shielded Enclosures With Apertures And Attached Wires In A Real-World Environment, Bruce Roy Archambeault Jan 1997

Modeling Of The Electromagnetic Radiation From Shielded Enclosures With Apertures And Attached Wires In A Real-World Environment, Bruce Roy Archambeault

Doctoral Dissertations

A hybrid modeling technique using the Finite-Difference Time-Domain (FDTD) approach in conjunction with the Method of Moments (MoM) approach was developed to allow simulation of electromagnetic interference (EMI) emissions through apertures due to sources within a shielded enclosure. These apertures can include air ventilation openings, option card slots, mating cover seams, or any other opening in the metal shielded enclosure. Modeled emission results can now be directly compared to U.S. and other countries' regulations to allow engineers to predict compliance before hardware prototypes are built. The effects of the test environment, including ground plane and specified measurement distance, as well …

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