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Wright State University College Of Engineering And Computer Science Bits And Pcs Newsletter, February 1989, 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.

The Influence Of Fly Ash On Obtaining Quality Plastic And Hardened Properties Of Portland Cement Concrete, Ashaari Bin Mohamad

Doctoral Dissertations

Coal fly ash produced at the Merrimack Power Station, Bow, New Hampshire was tested for chemical and physical properties. Concretes made with these fly ashes were tested for their plastic and hardened properties and compared to ordinary portland cement concrete.

An experimental test burn substituting coal with Refuse-Derived-Fuel(RDF) consisting mainly of waste paper and plastic with heating value of 6000 to 8000 BTU/lb. was done by Public Service of New Hampshire at the Merrimack Power Station. Five percent and ten percent RDF was substituted, on a BTU basis, for coal in the test burns. Twelve (12) test burn days were …

A Conceptual Design Of A Propulsion System For An Autonomous Underwater Vehicle, Gerald Sedor

Doctoral Dissertations

The need for developing propulsion systems to support missions of increased endurance for autonomous underwater vehicles is investigated and a conceptual system is proposed, based on currently available technology and desired system characteristics.

The investigation evaluates and ranks alternative energy sources and proposes the use of a closed Brayton cycle gas turbine power plant using a chemical energy heat source with a metallic fuel. A thruster system using electric propulsion motors and screw propellers is selected. Evaluation factors include reliability, depth independent operation, weight, endurance, quietness and efficiency. Reliability of the proposed system is analyzed and the design modified to …

Using Expert Systems In Maintenance Monitoring And Management., Tahoomars Rastin

LSU Historical Dissertations and Theses

In this research, a model for fault diagnosis of equipment is discussed. The model discusses the use of multi-variable monitoring for a more precise means of equipment malfunction trouble shooting. Also within this model means are discussed for automatically generating work-orders. Equipments are divided into subsystems. The subsystems are broken down into sub-subgroups and further down to individual parts. Preventive maintenance techniques, along with expert system technology, are used to develope the maintenance expert system (MES). Statistical pattern recognition techniques are used as a way to describe the relationship between categories of equipment. The relationships shown here are mostly that …

Wright State University College Of Engineering And Computer Science Bits And Pcs Newsletter, January 1989, 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.

Constitutive Equations For Large Deformation, Rate-Dependent Plasticity For Metal Alloys., Louay Nadhim Mohammad

LSU Historical Dissertations and Theses

A system of constitutive equations is proposed that describes the viscoplastic behavior of a class of metal alloys when subjected to large deformations. The model is purely elastic before the plastic state is reached, and becomes elastic/viscoplastic after the plastic state has been exceeded. Three main assumptions are made with regard to the strain-rate dependency in the proposed formulation. The inelastic strain rate tensor is assumed to be normal to each point of the rate dependent convex yield surface. The initial yield stress obtained from uniaxial tests is assumed to be dependent on the rate of strain loading. Finally, the …

Evaluation And Improvement Of Maintenance Scheduling Techniques., Nat Khemakavat

LSU Historical Dissertations and Theses

The objective of this research is to evaluate present maintenance scheduling systems and to suggest improvements or alternatives. The widely used priority-based maintenance scheduling system is shown to be inappropriate in a variety of scheduling circumstances. The major reason is the omission of any type of cost consideration. To overcome this shortcoming, a new maintenance scheduling model is proposed. Instead of using work-order priority as the primary scheduling criteria, the new system uses cost as the key scheduling component. That is, maintenance jobs are scheduled with the objective of minimizing total maintenance cost. Maintenance scheduling strategies based on the cost …

Modeling, Simulation, And Automatic Control For Optimum Drying And Storage Of Rough Rice In A Bin System., Jong Hoon Chung

LSU Historical Dissertations and Theses

A study on modeling, simulation, and automatic control for optimum drying and storage of rough rice in a farm-bin system was conducted to address some aspects of rice post-harvest technology. Resistance-type moisture sensors and temperature and humidity sensors were evaluated for continuously monitoring the conditions of air and grain. Models to predict rice moisture models during drying and storage were developed. Based on accuracy and predictability, the use of the capacitance-type humidity sensor is recommended over the resistance-type moisture sensor. A pressure drop model of airflow through rough rice was developed to aid in determining the optimum size and type …

Dynamic Models Of The High-Temperature Desulfurization Process In A Fixed-Bed Reactor., Ching-Pin Wang

LSU Historical Dissertations and Theses

The widespread adoption of coal-fueled advanced electric power generation systems depends upon the ability to remove H$\sb2$S from the gasifier product. While H$\sb2$S can be removed by traditional wet scrubbing methods, sensible heat is lost, thereby reducing the overall system efficiency. High temperature desulfurization is now possible using newly developed metal oxide sorbents which are capable of reducing the H$\sb2$S concentration to less than 10 ppmv from a laboratory scale fixed-bed reactor using a simulated coal gas. In this study, reactor simulation models capable of describing the high temperature sulfidation and regeneration reactions of metal oxide sorbents in a fixed-bed …

Land Subsidence And Saltwater Intrusion In Coastal Areas., Song-Kai Yan

LSU Historical Dissertations and Theses

Land subsidence and saltwater intrusion problems are encountered concurrently or individually in many coastal areas, especially where heavy pumping is exerted. In order to evaluate the extent and progress of these two phenomena in quantity and quality, a two-dimensional model, the STRALAN (Solute $\underline{\rm Tra}$nsport and $\underline{\rm Lan}$d Subsidence) model, is developed to simulate fluid movement, solute transport and land subsidence in a non-homogeneous, anisotropic, compressible and sloping aquifer system. The governing equations of the model, i.e., the fluid mass balance equation, solute mass balance equation and land subsidence equation for confined or unconfined as well as for sloping aquifers …

An Anisotropic Finite Plasticity Model For Continuum Damage Mechanics., Peter Issa Kattan

LSU Historical Dissertations and Theses

A constitutive model is formulated for anisotropic continuum damage mechanics using first elasticity and then finite strain plasticity. The formulation is given in spatial coordinates (Eulerian reference frame) and incorporates both isotropic and kinematic hardening. The von Mises yield criterion is modified to include the effects of damage through the use of the hypothesis of elastic energy equivalence. A modified elasto-plastic stiffness tensor that includes the effects of damage is derived within the framework of the proposed model. The damage variable used represents average material degradation which reflects the various types of damage at the microscale level like nucleation and …

A Total Lagrangian Finite Element Analysis For Metal Forming With Application To Metal Extrusion., Mehrdad Foroozesh

LSU Historical Dissertations and Theses

A detailed formulation for finite element analysis of metal forming problems is carried out in this work. It incorporates every aspect of the analysis, including the iterative solution procedures for geometric and material non-linearities, implementation of the material model, and formulation of curved contact boundaries. The finite element formulation is based on a Total Lagrangian approach which by-passes the use of the Jaumann stress rate tensor commonly used in the Updated Lagrangian formulation. The yield model used is of the von Mises type with both kinematic and isotropic hardening and is formulated in the Eulerian space. This model is then …

Geometric Modeling And Recognition Of Elongated Regions In Images., Charles Anthony Lipari Ii

LSU Historical Dissertations and Theses

The goal of this research is the recovery of elongated shapes from patterns of local features extracted from images. A generic geometric model-based approach is developed based on general concepts of 2-d form and structure. This is an intermediate-level analysis that is computed from groupings and decompositions of related low-level features. Axial representations are used to describe the shapes of image objects having the property of elongatedness. Curve-fitting is shown to compute axial sequences of the points in an elongated cluster. Script-clustering is performed about a parametric smooth curve to extract elongated partitions of the data incorporating constraints of point …

Fine Scale Velocity Measurements In A Turbulent Jet In A Confined Crossflow., Julie Ann Mathis

LSU Historical Dissertations and Theses

Measurements of the fine scale velocity field are made for a turbulent jet in a confined crossflow. With a crossflow velocity of 10.0 m/sec, jet-to-crossflow velocity ratios of 1, 2 and 4 are examined. Velocity measurements are obtained by laser velocimetry. The velocimetry system consists of a 15mW laser with a fringe mode optics setup, operated in the backscatter mode. Signal processing is accomplished with a tracker processer. At each measuring location, 28,400 velocity readings are obtained at a sampling frequency of 38,460 sec$\sp{-1}$. Calculations include construction of autocorrelation functions, Kolmogorov-normalized energy spectra and their moments, skewness and flatness of …

Natural Convection Above Heated Inclined Surfaces., John Anthony King

LSU Historical Dissertations and Theses

Motivated by a need to assess pollutant transport by upslope flows, an investigation has been conducted into the fundamentals of natural convection flow over inclined surfaces. Particular attention was focused on the influence of ambient fluid stability. Field studies were performed using tracer gas releases into the upslope flow over a Southern California mountain range. The field studies served to reveal the presence of a split slope flow recirculation and demonstrated the impact of this recirculation on the transport of pollutants from a valley. In order to pursue a controlled investigation of the phenomena found in the field work, a …

Arch: A Robust Construction Heuristic For The Layout Design Of Food Processing Facilities., George Robert Baskin

LSU Historical Dissertations and Theses

A Robust Construction Heuristic (ARCH) represents the first attempt to develop a facilities layout design algorithm tailored to the particular solution of the food processing facility layout problem where a fluctuating product mix due to seasonality or changes in consumer demand is typical. The foundation literature for this research comes predominantly from the industrial engineering, management science, and food science fields. Construction heuristics built layouts from scratch and provided poor quality results. Robustness algorithms had no simplifying heuristics but were reported to yield potentially higher quality layouts than traditional algorithms for layout problems with fluctuating product mixes. ARCH was developed …

Systolic Array Implementations With Reduced Compute Time., Abdulkader Omar Barbir

LSU Historical Dissertations and Theses

The goal of the research is the establishment of a formal methodology to develop computational structures more suitable for the changing nature of real-time signal processing and control applications. A major effort is devoted to the following question: Given a systolic array designed to execute a particular algorithm, what other algorithms can be executed on the same array? One approach for answering this question is based on a general model of array operations using graph-theoretic techniques. As a result, a systematic procedure is introduced that models array operations as a function of the compute cycle. As a consequence of the …

Non-Newtonian Fluid Flow In Eccentric Annuli And Its Application To Petroleum Engineering Problems., Mustafa Haciislamoglu

LSU Historical Dissertations and Theses

The fluid flow in the annular gap in oilwells is a complex problem. The geometry of the annulus is customarily simplified to concentric annular flow. In this study, a fluid flow model is developed allowing annulus to be eccentric: inner pipe located anywhere in the annulus. Thus, a more realistic representation of the actual geometry is obtained. An equation of motion that defines flow of non-Newtonian fluids in eccentric annuli is derived. A numerical solution of this equation is presented. The velocity profiles, the viscosity profiles, and the flow rate vs frictional pressure loss gradient relationship are calculated for varying …

Harmonic Measurement And Reduction In Power Systems., Rutisurhata Kurniawan Hartana

LSU Historical Dissertations and Theses

Harmonic voltages and currents are created by nonlinear loads in power systems. These harmonics can cause serious problems to the energy suppliers (utility companies) and energy users (consumers). This dissertation presents new techniques for harmonic measurement and the accompanying problem, harmonic reduction. To reduce harmonics, the location and magnitude of harmonic sources must be known a priori. However, to measure and monitor harmonic sources requires specialized instrumentation that is not generally permanently installed at most buses. In this study, a method is developed to use neural networks in conjunction with state estimation for monitoring and estimating harmonic sources with only …

Analytical Studies Of Wireline Formation Testing And Pressure Losses Across Gravel Packs., Turhan Yildiz

LSU Historical Dissertations and Theses

A three-dimensional (3-D) analytical model was developed to improve the analyses of the transient pressure response of a reservoir to wireline formation testing (WFT). Available analysis techniques of the WFT oversimplify the flow geometry by assuming either a radial or a spherical flow pattern. The proposed model simulates the exact flow geometry of the WFT flow pattern. The model was derived by solving the 3-D diffusivity equation coupled with the boundary conditions prevailing during the test. The Laplace transformation and the separation of variables were used to obtain the solution. The solution is expressed in terms of the infinite Fourier-Bessel …

A Dynamic Model Of Diverter Operations For Handling Shallow Gas Hazards In Oil And Gas Exploratory Drilling., Otto Luiz Alcantara Santos

LSU Historical Dissertations and Theses

This dissertation presents an experimentally verified numerical simulator to predict dynamic loads imposed on diverter systems during the well unloading following a shallow gas blowout event. Chapter I presents an overview of important aspects of well control and diverter systems. Also in this chapter, the objective of this research is precisely defined. The following chapter reports the latest efforts of the oil industry to provide diverter systems with more reliable designs and operational procedures. In Chapter III, the apparatus and procedures for the experimental work are discussed. Nine experimental runs have been conducted and the results are reported in a …

A Comprehensive Methodology For Algorithm Characterization, Regularization And Mapping Into Optimal Vlsi Arrays., Hassan Reda Barada

LSU Historical Dissertations and Theses

This dissertation provides a fairly comprehensive treatment of a broad class of algorithms as it pertains to systolic implementation. We describe some formal algorithmic transformations that can be utilized to map regular and some irregular compute-bound algorithms into the best fit time-optimal systolic architectures. The resulted architectures can be one-dimensional, two-dimensional, three-dimensional or nonplanar. The methodology detailed in the dissertation employs, like other methods, the concept of dependence vector to order, in space and time, the index points representing the algorithm. However, by differentiating between two types of dependence vectors, the ordering procedure is allowed to be flexible and time …

An Experimental And Computational Investigation Of Turbulent Jet Impingement In A Confined Crossflow., Keun Sun Chang

LSU Historical Dissertations and Theses

An experimental and computational investigation is made for the turbulent flow field generated by a jet discharging transversely into a confined moving stream. For jet to cross flow mean velocity ratios (R) equal to 2 and 4, measurements are made using a laser-Doppler velocimeter (LDV) in conjunction with a tracker processor. Quantities measured include mean velocities, turbulence intensities, turbulent shear stress, and dissipation rates of the turbulent kinetic energy. The jet flow Reynolds numbers investigated are 1.5 $\times$ 10$\sp4$ for R = 2 and 3.0 $\times$ 10$\sp4$ for R = 4. The structured nature of the turbulent flow field is …

Optimal Design And Control Of Distribution System Capacitors., Nugroho Iwan Santoso

LSU Historical Dissertations and Theses

The rapidly escalating costs of generation and transmission facilities as well as energy production have focussed attention on the need to optimize system capacity release and energy losses. The problem is generally solved by controlling the voltage or reactive power which also has a pivotal role within the distribution automatization schemes. A review of reactive power compensators and methodologies in designing and controlling distribution capacitors is given. In the presence of voltage source harmonics, a local load reactive power compensation method, cost-constrained power factor optimization using an LC compensator, is discussed. A new methodology based on a piecewise method for …

Wright State University College Of Engineering And Computer Science Bits And Pcs Newsletter, November 1988, College Of Engineering And Computer Science, Wright State University

BITs and PCs Newsletter

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

Irish H & V News

Building Services Engineering

No abstract provided.

Twist-Bending Vibrations Of Horizontally Circular Curved Beams Considering Effects Of Transverse Shear, Rotatory Inertia And Warping, Bor-Tsung Hsiao

Doctoral Dissertations

This thesis is devoted to the dynamic analysis of horizontally circular curved beams. The direct stiffness method is used to derive the dynamic stiffness matrix for finding the natural frequencies and joint moments of curved beams having different rectangular cross-sections. Four examples are presented to illustrate the application of the proposed method and to show the effects of rotatory inertias, shear deformation, warping and opening angle of the arc on the beam. First three examples are for the free vibration of the beam. In these examples, beams with different thickness are used for finding effects of warping. In each example, …

Modelling Of Passive Contaminant Transport In River Sediments., Susan Anne Savant-Malhiet

LSU Historical Dissertations and Theses

Contaminant transport from riverine sediments was investigated via physical and mathematical models. Due to its remote nature, there exists a lack of understanding of transport mechanisms and rates at the sediment-water interface of rivers. This dissertation is focused on evaluation of potential abiotic transport processes which affect the movement of contaminants across this sediment-water interface. Only non-dispersive transport of passive contaminants was considered allowing the research to focus on the movement of the sediment pore water which carries the contaminants. The abiotic processes studied include the advection by flow of sediment pore water and the movement and turnover of sediment …

Minimum Time Motion Of A Robotic Manipulator., Heon Hwang

LSU Historical Dissertations and Theses

This dissertation treats the modeling, analysis, and trajectory control of a robotic manipulator to execute specified point-to-point tasks. The relative coordinate representation of kinematic and dynamic variables is defined using vectors and matrices based on coordinate transformations. A kinematic modeling of a manipulator is performed using Denavit-Hartenberg link parameters. For given end-effector information (location and orientation), a stable and efficient iterative numerical algorithm for a joint solution is developed. A modified general Gauss elimination and a direct minimum search are combined with other refinements to yield fast convergency and stable results. This algorithm can be used as a routine solution …

Multivariable Adaptive Control Design Under Internal Model Control Structure., Ivan Patricio Solar

LSU Historical Dissertations and Theses

A new adaptive multivariate control scheme has been devised. The method combines the best characteristics of conventional adaptive systems and internal model control (IMC) structure. The control scheme builds by itself the required models and avoids the ambiguities in the definition of performance specifications. The problem of plant inversion associated with the IMC structure has been solved. The method introduced in this work is based on the properties of the Smith-McMillan form. However, the method does not require the explicit determination of the form. Furthermore, the computation of a stable plant inverse requires only matrix inversion and scalar polynomial factorization. …