Digital Commons Network^™

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. …

Efficient Mapping Of Neural Network Models On A Class Of Parallel Architectures., Behnam Seyed Arad

LSU Historical Dissertations and Theses

This dissertation develops a formal and systematic methodology for efficient mapping of several contemporary artificial neural network (ANN) models on k-ary n-cube parallel architectures (KNC's). We apply the general mapping to several important ANN models including feedforward ANN's trained with backpropagation algorithm, radial basis function networks, cascade correlation learning, and adaptive resonance theory networks. Our approach utilizes a parallel task graph representing concurrent operations of the ANN model during training. The mapping of the ANN is performed in two steps. First, the parallel task graph of the ANN is mapped to a virtual KNC of compatible dimensionality. This involves decomposing …

Studies Of The Morphology And Dynamics Of Flame-Generated Agglomerates Using Dynamic Light Scattering., Glenn Michael Waguespack

LSU Historical Dissertations and Theses

Accurate determination of the morphology and dynamics of aerosols consisting of agglomerated sub-micron sized particulates is needed for soot formation studies, process monitoring in flame-based materials synthesis applications, and pollution control studies. The objective of the current study is to investigate the application of dynamic light scattering (DLS) to flames as an extension of current measurement technologies. Unlike previous DLS flame studies, conventional polarized DLS is supplemented with depolarized DLS measurements to account for the agglomerates' anisotropy. Because unavailable relationships between the agglomerates' morphological parameters and the Brownian translational and rotational diffusion coefficients under non-continuum conditions are required for accurately …

Removal Of Hydrophobic Organic Compounds And Surfactants From Wastewater: Polyaphron-Enhanced Solvent Extraction And Biodegradation., Chunlong Zhang

LSU Historical Dissertations and Theses

Surfactant based processes are emerging and becoming increasingly important in pollution control. A novel predispersed solvent extraction (PDSE) technique using surfactant based colloidal liquid aphrons (CLAs or polyaphrons) and colloidal gas aphrons (CGAs) for the removal of hydrophobic organic compounds (HOCs) from the aqueous phase was studied. The process involves an extraction of HOCs into CLAs, followed by a flotation using CGAs. Polyaphrons were characterized by a particle size analyzer. The size distribution was found to be bimodal. The effects of surfactant types, surfactant concentrations and storage times on the size distribution were studied. Polyaphrons have long shelf-lives and are …

Performance And Analysis Of Segmented Multiple Bus Systems., Jungjoon Kim

LSU Historical Dissertations and Theses

The dissertation introduces a new class of bus-based systems called the Segmented Multiple Bus System (SMBS). One of the unique characteristics of the SMBS is that it allows the exploitation of memory reference locality even though it is a bus-based nondirect network. This comes from the architectural interconnection feature that the SMBS can be viewed as a large-scale multiple bus system (MBS) that has been partitioned into smaller partitions called segments. Each such segment is in effect a small conventional MBS whose size is chosen so as to avoid bus loading problems. The SMBS overcomes the architectural limitations of bus-based …

Gravity-Assisted Tertiary Gas Injection Process In Water-Drive Oil Reservoirs., Bogdan Lepski

LSU Historical Dissertations and Theses

In dipping, water-drive reservoirs, substantial incremental oil can be produced using gravity-assisted gas injection improved recovery processes. These processes include the Double Displacement Process (DDP) and the Second-Contact Water Displacement (SCWD). The efficiency of these processes depends, in part, on phase distribution in the pore space after gas injection which in turn depends on interfacial and surface tensions (IFT) of the phases involved. The research described here-in pertains to experimental work performed to investigate various aspects of the DDP and the SCWD in both homogenous and heterogeneous rock types with dead oil/nitrogen and recombined-oil/methane fluid systems. Additional work was performed …

An Integrated Gps-Gis Methodology For Performing Travel Time Studies., Cesar A. Quiroga

LSU Historical Dissertations and Theses

This dissertation describes a methodology for conducting travel time studies based on global positioning system (GPS) receivers and geographic information system (GIS) technology. Compared to traditional approaches, the new methodology provides consistency, automation, finer levels of resolution, and better accuracy in measuring travel time and speed. These characteristics enable the detection of localized traffic effects much more efficiently than with traditional techniques. The new methodology automates the data collection and data reduction procedures, and provides improved procedures for documenting and analyzing travel time and speed data. As a result, large amounts of reliable travel time and speed data can be …

A Theory Of Cortical Neural Processing., David Timothy Young

LSU Historical Dissertations and Theses

This dissertation puts forth an original theory of cortical neural processing that is unique in its view of the interplay of chaotic and stable oscillatory neurodynamics and is meant to stimulate new ideas in artificial neural network modeling. Our theory is the first to suggest two new purposes for chaotic neurodynamics: (i) as a natural means of representing the uncertainty in the outcome of performed tasks, such as memory retrieval or classification, and (ii) as an automatic way of producing an economic representation of distributed information. We developed new models, to better understand how the cerebral cortex processes information, which …

A Computer Automated, Hydraulically Integrated Serial Turbidostat Algal Reactor (Histar): Mathematical Modeling And Experimental Analysis., Chandra Sekhar Theegala

LSU Historical Dissertations and Theses

Conceptually, the Hydraulically Integrated Serial Turbidostat Algal Reactor (HISTAR) has two components: (1) sealed turbidostats for producing a high quality algal inoculum, and (2) a series of unprotected inter-connected continuous flow stirred tank reactors (CFSTRs) for mass producing algae under approximated plug flow conditions. The hydraulic retention time of each individual CFSTR ($\theta\sb{\rm n})$ is set low enough (dilution is set high) that any suspended organisms (both contaminants and desired algae) entering the CFSTR would be washed to the next CFSTR well within their doubling time. However, as the turbidostats are employed to inoculate the first CFSTR on an almost …

Feedback Linearizing Control Strategies For Chemical Engineering Applications., Michael James Kurtz

LSU Historical Dissertations and Theses

Two widely studied control techniques which compensate for process nonlinearities are feedback linearization (FBL) and nonlinear model predictive control (NMPC). Feedback linearization has a low computational requirement but provides no means to explicitly handle constraints which are important in the chemical process industry. Nonlinear model predictive control provides explicit constraint compensation but only at the expense of high computational requirements. Both techniques suffer from the need for full-state feedback and may have high sensitivities to disturbances. The main work of this dissertation is to eliminate some of the disadvantages associated with FBL techniques. The computation time associated with solving a …

Tribological Behavior Of Duplex Nitrogen Diffusion/Dlc Coating Treatments., Yan Liu

LSU Historical Dissertations and Theses

Diamond-like carbon (DLC) coatings have high potential for developing advanced tribological systems and the overall objective of the present research is to provide a framework to theoretically design and experimentally develop and study such systems of interest. The present research concentrates on the following specific aspects: the fundamental wear mechanism of DLC coatings; finite element (FE) modeling to understand the stress distribution in coating/substrate system under indentation and friction; and the influence of graded interface on the tribological behavior of DLC coatings. The experimental results showed that DLC films possess low friction coefficient ($f\sb{init}$: 0.12-0.20, $f\sb{fin}$: 0.06-0.08) and low wear …

Coastal Restoration Using Pipeline-Conveyed Sediments., Catherine Faith Voisin

LSU Historical Dissertations and Theses

A spreadsheet program was successfully developed which determines the engineering requirements for pipeline transport of sediments from dredge sites to wetland restorations sites. The program called SLURRY.XLS involves several new correlations. A new correlation for determining the critical velocity of particle transport is presented. New correlations were statistically developed for determining the drag coefficient of particles. The spreadsheet also successfully determines settling velocities of the individual particle sizes in any settling regime. A second spreadsheet program entitled "CONSOL.XLS" uses geotechnical principles of consolidation for determining marsh surface elevation with and without hydraulic fill versus time. The CONSOL.XLS program permits the …

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 …

An Experimental Investigation Of The Effects Of Elastic Modulus And Yield Strength On Fracture Surface Interference In Shear Loaded Cracks, Ronald U. Goulet

Doctoral Dissertations

An experimental process was developed to study the effects of material properties on fracture surface interference in Mode II loaded cracks in 7075 aluminum. 4340 and 8642 steels. Factors studied included elastic modulus, yield strength, mode mixity and fracture surface geometry. An asymmetric four point bend specimen and fixture was developed to apply pure Mode II and mixed Mode I and II loads to edge cracks. Three dimensional displacement fields were measured as a function of applied load using an electro-optical holographic interferometric facility. Stress intensity factors were obtained by fitting observed 2-D field displacements to basis functions derived from …

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. …

Numerical Analysis For Blood Distribution In Complete Flow Cross-Section Microvascular Networks, Jewen Xiao

Doctoral Dissertations

As the blood flows through a bifurcation, the axisymmetric red blood cell concentration profile is skewed by plasma skimming. In the downstream segment of the bifurcation the concentration profile of red blood cells recovers symmetry by the red blood cell dispersion process.

In this study, the concentration convective equation, which models the red blood cell dispersion process, is solved with the method of finite differences in cylindrical coordinates. In the computation, a shear-induced diffusivity coefficient is used. The computed hematocrit ratios at the second bifurcation are compared with in vitro experimental data obtained from 50 $\mu$m serial trees with two …

An Experimental Investigation Of Thermally-Induced Deformation Of 1 Micron Thick Copper/Tantalum/Polymide High-Density Interconnect Structures, Dmitry V. Zhmurkin

Doctoral Dissertations

A new technique to estimate the out-of-plane thermal expansion coefficient (CTE) of several 1 $\mu$m thick, spin-coated polyimides is introduced. Arrays of parallel copper and polyimide lines of various aspect ratios on Si substrate were imaged in air at room temperature and at 97$\sp\circ$C using an atomic force microscope (AFM). The out-of-plane CTE of the polyimides was estimated by matching the experimental results with the predictions of finite element models with different out-of-plane parameters. For FPI-135 (6FCDA-TMOB) polyimide the out-of-plane CTE was found to be $\approx$260 ppm/$\sp\circ$C, for FPI-136 (PMDA-6FDA-TFMOB) polyimide $\approx$120 ppm/$\sp\circ$C. Polyimide lines with widths equal to or …

Two-Echelon Logistics Model For Recoverable Items With Lateral Supply In The Army., Kwanghui. Chai

Electronic Theses and Dissertations

This paper develops a Two-echelon logistics model for recoverable items with lateral supply in a single period in the Army. It derives formulas for distribution and inventory costs, and determines the optimal stock level at a depot and at a base to minimize the backorders. During the period, a Poisson demand and distinct units of operating bases which stocks can be shared are assumed. It allows the lateral supply between operating bases. A two-phase method is used to get solutions to the stock level constrained optimization problem. The outcome of this paper can be applied to lower level of logistics …

Vibration Balancing Analysis Of A Dual Face Mill Eccentric Grinder Machine Head., Jason Kyle. Kushniruk

Electronic Theses and Dissertations

Balancing of machinery is a well known technical aspect of engineering which is practiced throughout the world. Many studies have been performed to optimize the models and methods used to make rotor balancing faster and more efficient. This thesis deals with the unique problems associated with the balancing of eccentrically designed spindles for the machine tool industry. Cobra Machine Tool Limited has designed and patented the newest form of combination face mill and grinder operation in North America. The study performed in this analysis provides a benchmark for further vibration studies by the company in the future. Standard vibration measurement …

Viscometric Properties Of Dilute Lubricating Oil-Polymer Solutions Over A Wide Temperature Range., Daniel John Christopher. Lariviere

Electronic Theses and Dissertations

The effects of polymers used as viscosity index improvers in lubricating oils are of interest to the petrochemical industry. Polymers are used to reduce the thinning effect of temperature on viscosity. The densities and kinematic viscosities of four viscosity index improvers at five concentrations were measured at $-20,\ -10$, 0, 10, 20, 40, 60, 80, 100, 120, and 150$\sp\circ$C in a 95% saturate base oil. Various models for liquid viscosity prediction were tested using the experimental data. The intrinsic viscosities were calculated using the equations proposed by Huggins (1942), Kraemer (1938), Schulz and Sing (1945), and Martin (1942) as a …

A 0-1 Integer Programming Model For The Simultaneous Allocation Of Operations Of Part Types And Grouping Of Machine-Tool Combinations., Franklin Samuel Jaiselvan. Foulger

Electronic Theses and Dissertations

In today's competitive world, for manufacturers to survive in the market and to compete on a global level, several innovative strategies are being developed and practised. In industries which manufacture a variety of products in lots, one of the well known manufacturing strategies or systems is cellular manufacturing systems (CMS). CMS has several advantages especially for manufacturers who produce a medium variety of products in medium volumes. The tangible benefits are reduction in cycle time of the product, reduced inventory, improved quality, possibility to meet customer demands on time etc.; the intangible benefits are flexibility in the system, increased control …

Scheduling In A Dual Resource Constrained System Using Genetic Algorithms., Vishvas. Patel

Electronic Theses and Dissertations

In this research a solution methodology and a software program system for assignment of dual resources (Machines and Workers) were developed. By considering two dual resource constrained problems as the candidate problems, an optimized GA based heuristic was developed. First genetic algorithms were used to determine the optimal staffing level which can be viewed as a basic design decision. Second, genetic algorithms were used to make short range control decisions regarding the operations of dual resource constrained shop. Six different dispatching rules such as SPT, EOPNDD, EDD, FCFS, LSO, LPT and eight performance criteria were used. The performance of each …

Single-Angle Compression Members Welded By One Leg To Gusset Plates., Sherief Sharl Shukry. Sakla

Electronic Theses and Dissertations

Single-angle compression members are simple structural elements that are very difficult to analyse and design. These members are usually attached to other members by one leg only. Thus the load is applied eccentrically. To further complicate the problem, the principal axes of the angle do not coincide with the axes of the same or truss of which the angle is a part. Although it is known that the end conditions affect the ultimate load carrying capacity of these members, procedures have not been developed to do this as it is difficult to evaluate the end restraint in many practical cases. …

Smart Drilling: A Computer-Based System For Planning Drilling Operations., Jia. Ma

Electronic Theses and Dissertations

In this thesis, a prototype computer aided process planning system--Smart Drilling System is presented. The system will be able to automatically generate plans for multiple hole drilling process, such as tool selection, drilling sequence, and etc. The system contains four modules: (1) Tool selection module, (2) Machining condition design module, (3) NC code generation module, and (4) Simulation module. In the tool selection module, a generative searching and planning algorithm is applied. Fuzzy logic was utilized to make decisions in tool selection. The module can group the drills according to their size and shape, and select optimal drills that will …

Prediction Models For The Integration Of New Technology Into The Automotive Manufacturing Infrastructure., Leo Paul. Oriet

Electronic Theses and Dissertations

With the introduction of increasingly expanded world markets in the 1990's, manufacturers are now obliged to compete with the best the world has to offer. Human infrastructures working with robust, capable and in-control processes depend on comprehensive appraisal of the Ergonomic implications for new technologies introduced in manufacturing operating systems. These core values and beliefs are now becoming part of a tightly linked decision-making process which is now being increasingly utilized by most successful manufacturers of world class products. World class manufacturers will welcome and integrate new technologies with the human infrastructure and do whatever it takes for worker protection. …

Thickness Measurement Of Curved Multilayered Polymer Structures Using The Ultrasonic Pulse-Echo Method., Hong. Shao

Electronic Theses and Dissertations

Ultrasonic inspection is accomplished by using electronically controlled pulses introduced into a material from an outer surface. Then, the ultrasonic energy travels within the material, finally reaching again an outer boundary. Material condition is diagnosed from characteristics of the receive ultrasonic energy. The technique of using ultrasonic pulse echo to investigate and examinate the thickness of curved multilayered structures will be presented in this thesis. It also studied physics conditions which the curvatures of multilayered polymer systems might effect thickness measurements. The real location of the focus of an acoustic beam in curved layered structures was calculated by a ray-optical …

Performance Of Composite Piping Systems: Thermal, Fire Endurance, And Joining Characteristics., Michael Andre Stubblefield

LSU Historical Dissertations and Theses

Composite piping systems are becoming the "System of Choice" in many applications previously the domain of metallic piping systems. For full acceptability and usage of these composite piping systems, new innovative approaches must be developed. Three areas of development are addressed; (i) thermal efficiency, (ii) fire endurance, and (iii) joining techniques. In the development of the energy conserving composite pipe, the thermal contact resistance acts as an additional insulating layer. A model and device to predict and measure the contact resistance for a pipe system has been developed. A corrugated layer, which acts as an enhanced contact resistance layer, forms …

A Study Of The Effect Of Energetic Flux Bombardment On Intensified Plasma-Assisted Processing., Albert Amatey Adjaottor

LSU Historical Dissertations and Theses

An investigation of the plasma nitriding mechanism under intensified conditions (average particle energy up to 1200 eV) was carried out using a triode configuration. The significance of the different physical processes taking place during intensified plasma nitriding, such as sputtering, implantation, defect generation, redeposition and diffusion were investigated experimentally, while theoretical predictions were obtained by using the TRIM (transport of ions in matter) code. A titanium-base alloy was selected as the substrate material. Sputtering yield in an inert atmosphere was found to exhibit three regimes as a function of incoming particle energy. The low energy and high energy regimes were …

Modelling The Allocation Of Pallets In A Flexible Manufacturing Cell., Balakrishnan. Baskar

Electronic Theses and Dissertations

Pallets are an essential part of manufacturing operations. This research concentrates on pallets for machining and, in particular, pallets for use in a flexible manufacturing cells (FMC). Flexible manufacturing has received widespread attention in the modern manufacturing environment. A close look at the research done on different areas of flexible manufacturing shows that the aspect of pallets in the design stage has been neglected. The objective of this research, therefore, is to develop mathematical programming models which deals with the palletizing problem in flexible manufacturing. The models assume that there is a set of existing machines in a manufacturing shop …

The Effect Of Elbow Position And Grip Span On Isometric Grip Strength And Force Distribution Of Fingers., Xuewei (Sue). Chen

Electronic Theses and Dissertations

Injuries to the hand, lower arm, and shoulder are often attributed to inappropriate use or poor design of hand tools. Isometric grip, performed with the angled handles of pliers was investigated in this study. For this thesis, three factors were studied. They were grip type (traditional and reversed grip), elbow position (0$\sp\circ$, 30$\sp\circ$, 60$\sp\circ$, 90$\sp\circ$, and 120$\sp\circ$), and grip span (50, 60, and 70 mm). The resultant forces between the jaws of the pliers and finger forces were measured under each condition. The purpose of this study was to evaluate the effect of elbow position and grip span on grip …