Engineering Commons^™

Ole Miss Engineer 1992

Ole Miss Engineer

No abstract provided.

Computational Simulation Of Flow Through Elbows In The Approach Piping Systems To A Headbox, Kasinathan Ramanathan

Masters Theses

The successful operation of the wet end in a paper machine is highly dependent on the approach piping system. Sheet basis weight stability and ease of making wet end adjustments are greatly impaired by improperly designed approach piping systems. Most problems in headbox approach piping occur when the flow splits, combines, and passes through elbows.

Elbows create cross flows, flow separation, and eddies, and play an important role in the uniform and stable delivery of the pulp into the headbox. The effect due to an elbow lasts for a considerable distance downstream of the elbow and is severe when two …

The Indentation Of Foam Pattern Surfaces By Coordinate Measuring Machine Probes, Sanjay Nenawati

Masters Theses

When coordinate measuring machines are used to measure the complex shapes of foam patterns, the spherical probe tips indent into the soft surface of the pattern. Such indentation represents a measurement error since the indicated dimension will not be the same as the actual dimension. To determine the magnitude of error, the depth of probe tip indentation into PMMA and EPS foam surface (i.e., elastic indentation) was measured as a function of time, applied load, and foam density. The residual indentation after the removal of the load (i.e., plastic indentation) was also studied.

The depth of elastic indentation increased with …

Control Of Low-Speed Turbulent Separated Flow Over A Backward-Facing Ramp, John C. Lin

Mechanical & Aerospace Engineering Theses & Dissertations

The relative performance and flow phenomena associated with several devices for controlling turbulent separated flow were investigated at low speeds. Relative performance of the devices was examined for flow over a curved, backward-facing ramp in a wind tunnel, and the flow phenomena were examined in a water tunnel using dye-flow visualization. Surface static pressure measurements and oil-flow visualization results from the wind tunnel tests indicated that transverse grooves, longitudinal grooves, submerged vortex generators, vortex generator jets (VGJ’s), Viets’ fluidic flappers, elongated arches +a + a (positive angle of attack), and large-eddy breakup devices (LEBU’s) +a + a placed near the …

Development Of A Model Updating Technique For Controls-Structures Integrated Design Optimization, Angela Georges

Mechanical & Aerospace Engineering Theses & Dissertations

A model updating technique is developed with the intent of providing an efficient means of improving the accuracy of the modelling of the vibrational qualities of a large, flexible structure as it undergoes an integrated controls-structures design optimization. The proposed technique utilizes eigenvalue/eigenvector sensitivity information, two different model reduction methods which assign weights of importance to the vibrational modes of the structure, and modal switching based upon the modal weights determined by the model reduction methods. Issues associated with the numerical implementation of the proposed technique, such as discontinuities induced by modal switching, are also addressed.

The proposed model updating …

Characterization Of Trailing Line Vortices, Karla M. Mossi

Mechanical & Aerospace Engineering Theses & Dissertations

Mean velocity surveys were taken for axial or trailing line vortices produced behind a bi-wing vortex generator in a low-speed wind tunnel. Data were taken primarily with a seven-hole probe at a speed of 30m/s; but vortex steadiness was studied using smoke flow visualization over a speed range between 10 and 40 m/s. Various generator center body configurations were studied, with particular interest directed toward how a centerline jet and an asymmetric, unsteady circumferential flow influenced the mean velocity profiles. This study found that a centerline jet did not produce a well-behaved two-cell vortex over the parametric range available in …

Eigenvalue Reanalysis Techniques Using Msc/Nastran, Christopher B. Barton

Mechanical & Aerospace Engineering Theses & Dissertations

Reanalysis is a numerical analysis technique that uses results from the total analysis of a design to compute the new response at a reduced computational cost. While there are many techniques available for reanalysis, the first order perturbation technique is investigated in this study. Because of its wide use in industry, NASTRAN finite element analysis software is used for total analysis, and as a basis for error. Since error seems rather unpredictable for this technique, it is sought, in this thesis, to find a reliable index for error so that a designer can know when the technique can be trusted. …

Modal Analysis Of Gyroscopically Coupled Sound-Structure Interaction Problems, Vijay B. Bokil

Mechanical & Aerospace Engineering Theses & Dissertations

In many practical situations we encounter sound-structure interaction between the fluid in a cavity and the flexible wall on the boundary. The aircraft cabin interacting with its fuselage and double-leaf partition walls interacting with the enclosed cavity are some of the typical examples. The vibratory behavior of the structure and the acoustical pressure inside the cavity are affected by this interaction.

In most of the cases, the governing differential equations for the coupled system can be shown to involve gyroscopic coupling. A special method has been applied to decouple the equations in terms of pairs of generalized coordinates and the …

Shape Sensitivity Analysis And Optimization Of Skeletal Structures And Geometrically Nonlinear Solids, Ching-Hung Chuang

Mechanical & Aerospace Engineering Theses & Dissertations

Formulations and computational schemes for shape design sensitivity analysis and optimization have been developed for both skeletal structures and geometrically nonlinear elastic solids. The continuum approach, which is based on the weak variational form of the governing differential equation and the concept of the material derivative, plays a central role in such a development.

In the first part of this work, the eigenvalue and eigenvector sensitivity equations for skeletal structures are derived with respect to configuration variables of joint and support locations. This derivation is done by the domain method as well as the boundary method. The discrete approach for …

A Computational Aerodynamic Design Optimization Method Using Sensitivity Analysis, Mohamed E. Eleshaky

Mechanical & Aerospace Engineering Theses & Dissertations

A new and efficient procedure for aerodynamic shape optimization is presented. The salient lineaments of this procedure are: (1) using a discrete sensitivity analysis approach to determine analytically the aerodynamic sensitivity coefficients; (2) obtaining the flowfield solution either by a computational fluid dynamics (CFD) analysis or, alternatively, by a flowfield extrapolation method which is based on a truncated Taylor's series; (3) defining the aerodynamic shape in such a way that it is not restricted to any class of surfaces and the optimizer automatically shapes the aerodynamic configuration to any arbitrary geometry; and (4) requiring no expertise other than that needed …

An Investigation Of Cutting Tool Chatter Vibration In Machine Tools, Arneil Olson

Graduate Research Papers

The purpose of this study was to assemble and condense the research and background literature available on cutting tool chatter vibration. Another requirement was to translate the highly technical language of the researcher into a form readily understandable to shop floor personnel.

Support staff called upon to assist in the elimination of chatter problems have not been given the informational resources necessary to effectively deal with the phenomenon. This information should be gathered from university libraries and cutting tool experts and combined into one basic reference work.

If collecting the references were all that was required they could simply be …

Preliminary Structural Design Of A Lunar Transfer Vehicle Aerobrake, Lance B. Bush

Mechanical & Aerospace Engineering Theses & Dissertations

An aerobrake concept for a Lunar transfer vehicle was weight optimized through the use of the Taguchi design method, structural finite element analyses and structural sizing routines. Six design parameters were chosen to represent the aerobrake structural configuration. The design parameters included honeycomb core thickness, diameter-to-depth ratio, shape, material, number of concentric ring frames, and number of radial frames. Each parameter was assigned three levels. The minimum weight aerobrake configuration resulting from the study was approximately half the weight of the average of all twenty seven experimental configurations. The parameters having the most significant impact on the aerobrake structural weight …

Neural Network Based Vowel Articulation Training Aid For The Deaf, Andrew E. Beck

Electrical & Computer Engineering Theses & Dissertations

Teaching the hearing-impaired to speak is both a challenging and rewarding task. Computer-based training aids are valuable teaching tools and complement the speech therapist in the speech training process. We have developed a computer based vowel articulation training aid designed to provide visual feedback for vowel production to the hearing-impaired user. This system transforms speech spectra from a multi-dimensional acoustic space to a two-dimensional phonetic space which is displayed on a computer monitor. The system signal processing includes feature extraction designed to mimic the properties of the human ear, and a transformation to a two-dimensional display space. The dimensionality transformation …

Unsteady Euler And Navier-Stokes Computations Around Oscillating Delta Wing Including Dynamics, Ahmed Abd-El-Bar Ahmed Salman

Mechanical & Aerospace Engineering Theses & Dissertations

Unsteady flows around rigid or flexible delta wings with and without oscillating leading-edge flaps are considered. These unsteady flow problems are categorized under two classes of problems. In the first class, the wing motion is prescribed a priori and in the second class, the wing motion is obtained as a part of the solution. The formulation of the first class includes either the unsteady Euler or unsteady Navier-Stokes equations for the fluid dynamics and the unsteady linearized Navier-displacement (ND) equations for the grid deformation.

The problem of unsteady transonic flow past a bicircular-arc airfoil undergoing prescribed thickening-thinning oscillation is studied …

An Investigation Into Manufacturing Quality Planning Concepts For New Manufactured Products With Recommendations For John Deere, Michael A. Henning

Graduate Research Papers

President Bush was quoted in 19 90 saying, "The improvement of quality in products and the improvement in services -these are national priorities as never before." (National, 19 9 0). Leadership through quality was also called the new competitive frontier by David Keams, Chief Executive Officer of Xerox Corporation (DeToro, 198 7) and 198 9 winner of the Malcolm Baldrige National Quality Award. For a manufacturing organization like Xerox a quality product is the result of many factors. Other corporations have come to the same realization of the importance of quality throughout their operations (Crosby, 19 9 1). He pointed …

Energy-Efficient Lighting For Florida Homes, Florida Solar Energy Center, Danny Parker

FSEC Energy Research Center®

Although lighting doesn't constitute a major portion of the average homeowner's electric bill (generally from 3 to 15 percent), you can cut your lighting costs significantly by installing new energy-efficient bulbs. As an added plus for Florida residents, these new bulbs produce less heat, meaning less work for your air conditioner.

A Mathematical Model And Simulation Of Natural Circulation Loop Thermalhydraulics, Nihad E. Daidzic

Aviation Department Publications

In this work, a simple, nonlinear, seventh-order mathematical model with lumped parameter analysis of the thermalhydraulic processes in a natural circulation steam boiler loop is presented. Digital simulation has been performed in order to predict open loop transients in severe accidental situations. Parts of the circulation loop such as the steam drum, downcomer, and riser were modelled separately on the basis of the integral balance equations. The two-phase flow in the steam drum and in the riser was modelled with the aid of a homogeneous-equilibrium, two-phase flow model. Special care was taken to ensure the stability of the numerical scheme, …

Experimental Feedback Of Fractional Order States Of A Lightly Damped Structure, Robert C. Mccall

Theses and Dissertations

The purpose of this study was to investigate the effectiveness of using fractional order time derivatives of position feedback signals in the active control of vibration. To that end, circuitry was built and evaluated that finds the half order derivative of an input signal. The magnitude responses of the fractional derivative circuits is very good, but there are large phase shifts present that may degrade the performance of the controllers. Two methods of incorporating the fractional derivative signals into the controller were examined. One method involved developing a similarity transformation that transforms an integer order state controller into an equivalent …

Energy Savings From Industrialized Housing Construction Systems And Roofing Tiles, Florida Solar Energy Center, Subrato Chandra

FSEC Energy Research Center®

Side-by-side tests were conducted in Cape Canaveral, FL to compare the cooling and heating energy use and electric peak demand requirements for two industrialized (Dow and Dome) and one conventional room-sized prototypes. The industrialized prototypes saved 11% to 16% in cooling energy and 45% to 56% in heating energy. The industrialized prototypes peak demand savings was 16% to 23% for cooling and 39% to 42% for heating. The energy performance of the Dome prototype was slightly better than that of the Dow. These results were as expected and are largely due to the higher insulation levels and greater air tightness …

Hypoid Gear Optimization, Selvaraj Ramachandran

Dissertations and Theses

A hypoid gear optimization procedure using the method of feasible directions has been developed. The objective is to reduce the gear set weight with bending strength, contact strength and facewidth-diametral pitch ratio as constraints. The objective function weight, is calculated from the geometric approximation of the volume of the gear and pinion. The design variables selected are number of gear teeth, diametral pitch, and facewidth. The input parameters for starting the initial design phase are power to be transmitted, speed, gear ratio, type of application, mounting condition, type of loading, and the material to be used. In the initial design …

Improving The Throughput Of Plasticating Extruders : Manufacture Of Non-Circular Pellets, Measurement Of Their Interparticulate Friction Coefficient, And Implications For Screw Design, Chia-Ying Liu

Dissertations

This dissertation addresses the hypothesis that the interparticulate friction coefficient of a bed of polymeric particulates is a function of the cross-section of the pellets. Most pellets have a circular cross-section especially those that are strand cut. But when such pellets constitute a particulate bed there are few restrictions to adjacent pellets turning with respect to each other, or of the beds rupturing under shear load. This rupture can occur in plasticating extrusion, and it results in a poorly mixed melt with an inhomogeneous temperature distribution. The temperature fluctuations cause viscosity fluctuations which in turn cause pressure fluctuations. The pressure …

Computer Aided Shape Optimization Using Finite Element Analysis, Charanpreet Singh Bagga

Theses

Various theories behind Computer Aided Shape Optimization are studied. A special attention is paid to the shape representation, mesh generation and refinement during the shape optimization process. Shape optimization process for a wall bracket is performed using the Computer Aided Engineering package of I-DEAS. Finite element analysis of the wall bracket is done and the stress distribution over the bracket is studied. The bracket is trimmed in the selected low stress regions using shape optimization capability of I-DEAS and an optimized shape of the wall bracket is obtained. The end product is evaluated using Supertab module of I-DEAS as well …

A Finite Element Thermal And Diffusion Analysis At Bearing Metal Interface In Extrusion Processes, Biju Dennis

Theses

A mathematical model is developed to study the effect of extrusion speed and the bearing length on the surface temperature along the die billet interface. The surface temperature distribution resulting from the plastic work done on the die billet interface is studied. Finite element analysis is done on the model incorporating the mass transport effect occurring during the extrusion process and the interdependence of various parameters are presented. Die wearing problem is analyzed considering the effect of diffusion. Thermal analogy of the diffusion problem is utilized in the development of the mathematical model for diffusion problem and finite element analysis …

Computer Numerical Controlled (Cnc) Machining Of Screws And Dies For Plasticating Extruders : Determination Of The Criteria For Implementing Cnc Machining, Nilesh H. Desai

Theses

The work of this thesis is dedicated to the manufacturing industry making production equipment to manufacture plastic products. The main theme of the thesis is to determine the criteria for implementing Computer Numerical Control machining to make parts with complex geometries for production equipment.

A small manufacturing company with job shop type of production was chosen as the subject and study of extruder manufacturing process was performed. The various available alternatives of CNC manufacturing units available in the market were chosen and their feasibility examined.

At present a large variety of CNC machine tools are available in the market, offered …

An Investigation On The Skill Requirements Of A Manufacturing Engineer In A Computer Integrated Manufacturing Environment, Wayne E. Frost

Graduate Research Papers

The problem for this study centers on these questions:

What skills will a manufacturing company's manufacturing engineers require to : 1) Implement successfully computer integrated manufacturing. 2) How will they obtain these skills?

Measured Natural Cooling Enhancement Of A Whole House Fan, Florida Solar Energy Center, Danny Parker

FSEC Energy Research Center®

An experimental study was carried out in the summer of 1991 to investigate the natural cooling potential of use of a whole house fan in Central Florida's hot and humid climate. The residential building, in Cocoa Beach, FL, is typical of much of the existing housing stock in Florida: a concrete block structure with R-11 ceiling insulation. The building was ventilated with all windows open during the three month summer test period (June-August). Air temperatures and relative humidity inside the home interior along with exterior meteorological conditions (insolation, wind speed, air temperature, relative humidity) were scanned every five seconds with …

On Capacity Modeling For Production Planning With Alternative Machine Types, Robert C. Leachman, Tali F. Carmon

Industrial and Manufacturing Engineering

Analyzing the capacity of production facilities in which manufacturing operations may be performed by alternative machine types presents a seemingly complicated task. In typical enterprise-level production planning models, capacity limitations of alternative machine types are approximated in terms of some single artificial capacitated resource. In this paper we propose procedures for generating compact models that accurately characterize capacity limitations of alternative machine types. Assuming that processing times among alternative machine types are identical or proportional across operations they can perform, capacity limitations of the alternative machine types can be precisely expressed using a formulation that is typically not much larger …

Bulletin No 4216 - Broadscale Boom Spraying, Roger Doyle, Gary Dorr, Des Gilbey, John Peirce

Bulletins 4000 -

For spraying to be effective it must do the job required at a minimum cost, with no unwanted side effects. It is impo1tant to use the right chemical at the right rate, at the right tin1e and in the best conditions.

It is just as important that both the sprayer and the way it is used allows you to meet this objective. This Bulletin will help you select the right boom sprayer, maintain it for efficient operation and use it efficiently and safely.

Effect Of Operating Conditions On Gearbox Noise, Fred B. Oswald, James J. Zakrajsek, Dennis P. Townsend, William Atherton, Hsiang Hsi Lin

Mechanical Engineering Faculty Publications

Low-contact-ratio spur gears were tested in the NASA gear noise rig to study the noise radiated from the top of the gearbox. The measured sound power from the gearbox top was obtained from a near-field acoustic intensity scan taken at 63 nodes just above the surface. The sound power was measured at a matrix of 45 operating speeds and torque levels. Results are presented in the form of a spectral speed map and as plots of sound power versus torque (at constant speed) and as sound power versus speed (at constant torque) Because of the presence of vibration modes, operating …

Comparison Of Analysis And Experiment For Gearbox Noise, Fred B. Oswald, A. F. Seybert, T. W. Wu, William J. Atherton

Mechanical Engineering Faculty Publications

Low-contact-ratio spur gears were tested in the NASA gearnoise rig to study the noise radiated from the top of the gearbox. Experimental results were compared with a NASA acoustics code to validate the code for predicting transmission noise. The analytical code is based on the boundary element method (BEM) which models the gearbox top as a plate in an infinite baffle. Narrow-band vibration spectra measured at 63 nodes on the gearbox top were used to produce input data for the BEM model. The BEM code predicted the total sound power based on this measured vibration. The measured sound power was …