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Three-Dimensional Transport Simulations Of The Dispersal Of Volcanic Aerosol From Mount Pinatubo, T. Duncan A. Fairlie

Mechanical & Aerospace Engineering Theses & Dissertations

A global finite-difference model that simulates the large-scale dynamics of the Earth's stratosphere and mesosphere is combined with a global spectral transport model to investigate aspects of the initial dispersal of the volcanic aerosol plume from the Mount Pinatubo eruption in 1991. Results of the modelling study are found to compare well with observations of the volcanic plume made from satellite instruments. Dynamical quantities, diagnosed from the simulated fields are used to provide insight into the evolution of the volcanic plume. Lagrangian trajectory analysis is used to help assess the performance of the Eulerian transport model and to highlight small-scale …

Analysis And Simulation Of Solidification For Phase Change Materials In A Cylindrical Container, H.C. Tien, J.S. Chang

Journal of Marine Science and Technology–Taiwan

The objective of this paper is to study the solidification problem of the phase change materials (PCM) in a thick-walled cylindrical container. Through varying each controlling parameter such as the thermophysical properties of wall (mold), wall thickness, aspect ratio of the container, initial temperature of PCM and the external cooling conditions, etc., the effect of each parameter on the solidification process is shown clearly. By knowing how a thick wall interacts with such a phase change phenomenon, it is therefore possible to well control the solidification process and also to improve the solid structure formed. In this study, convective boundary …

Nonlinear Dynamic Finite Element Simulation Of Hydroelastic Mounts For Light Weight Vehicles, Talla Jayapal Reddy

Masters Theses

Modern light weight vehicles generate large noise levels, that may need bulky classical rubber mounts to suppress. Hydroelastic mounts can significantly reduce the vibration level of current production automobiles without weight penalty. However, the highly nonlinear behavior of hydroelastic mounts has not been established yet and its use is, therefore, limited to trial and error design methods.

This study discusses the implementation of nonlinear finite element simulation of hydroelastic mounts using the ANSYS finite element code. Fluid elements are limited to linear analysis and therefore are incompatible with the nonlinear hyperelastic elements. A method is proposed to simulate the fluid …

Optimization Of The Seating Position In A Human-Powered Vehicle, Y. Lei, Mohamed Trabia, D. Too

Mechanical Engineering Faculty Research

Until recently, most of the human-powered vehicles (HPV) were designed focusing solely on its aerodynamics characteristic. In many of these HPV designs, the rider seating position was arbitrarily chosen without consideration of its effect on the rider's comfort and cycling effectiveness. Also, there is no guarantee that the seating position is related to maximum power output. Too (1991) used an experimental approach to determine that the rider will produce the maximum anaerobic power when the seat tube angle of a bicycle is at 75° whereas Hull and Gonzalez (1990) used an engineering approach to optimize the cycling biomechanics. However several …

Experimental Investigation Of The Effects Of Blowing Ratio Parameter On Heat Transfer To A Film-Cooled Flat Plate, Marco R. Valencia

Theses and Dissertations

The effects of blowing ratio on film cooling effectiveness were investigated. Two round-nosed test plates were used. One made of aluminum and the second of corian (low thermal conductivity). Injection at 35 degrees in the downstream direction was studied. Helium was mixed with air to produce a density ratio (coolant to mainstream) of 1.6 and 2.0, while the blowing ratio varied from 0.3 to 2.2. Surface temperature was measured by thin film gages located up to a nondimensional downstream distance X/D of 30. Two injection regimes, weak and strong, were found. In the weak regime, film cooling reduced gage heat …

On Orthogonal Collocation Solutions Of Partial Differential Equations, Herli Surjanhata

Dissertations

In contrast to the h-version most frequently used, a p-version of the Orthogonal Collocation Method as applied to differential equations in two-dimensional domains is examined. For superior accuracy and convergence, the collocation points are chosen to be the zeros of a Legendre polynomial plus the two endpoints. Hence the method is called the Legendre Collocation Method. The approximate solution in an element is written as a Lagrange interpolation polynomial. This form of the approximate solution makes it possible to fully automate the method on a personal computer using conventional memory.

The Legendre Collocation Method provides a formula for …

A Mathematical Model For The Prediction Of Depth Of Cut In The Course Of Awj Machining, Naijian Ma

Theses

The objective of this study is to develop a practical mathematical model for prediction of the depth of cut in the course of Abrasive Water Jet (AWJ) machining. Semi-empirical method which is an integration of theoretical derivation and statistical analysis is used for process description. A theoretical model was constructed based on kinetic energy conservation equation, physical relationship among operating parameters, abrasive size, material properties and cutting results. Then, correlation between the depth of cut and operational parameters was analyzed in order to improve the theoretical model. Finally, a regression equation representing 1000 samples was constructed.

Three statistical criteria were …

Coordinate Measuring Machines : A Modern Inspection Tool In Manufacturing, Matthias Richard Mantel

Theses

Coordinate Measuring Machines (CMM) are flexible and universal dimensional measuring devices with the capability for full integration into a CIM information network. Developed as highly precise measuring machines for specially designed measuring rooms, today's CMMs are more and more used in shop floor applications which is a hostile environment for a precise measuring tool. CMMs are offered in a variety of configurations and levels of automation. For the CMM buyer it is therefore essential to have an overview of the different types of CMMs and their subsystems before making a purchasing decision.

To obtain reliable measuring results that are used …

Simulation Of Manufacturing Cell Using Hoops Graphic Software And Siman Simulation Language, Parikh Vipul

Theses

Control of jobs being processed in manufacturing shop floor is important to management. The performance of job shop is affected by shop congestion due to arrival rate, batch size, number of machines, buffer capacity, process time variation, and dispatching rules use to load the jobs on the machine.

The job shop is a very complex system and hence, it is difficult as well as time consuming to obtained result using analytical method. A SIMAN simulation language is used to create generic model of a manufacturing cell and simulation analysis of those parameters variation such as job shop efficiency, the average …

Quasi-Static Deflection Compensation Control Of Flexible Manipulator, Jingbin Feng

Dissertations and Theses

The growing need in industrial applications of high-performance robots has led to designs of lightweight robot arms. However the light-weight robot arm introduces accuracy and vibration problems. The classical robot design and control method based on the rigid body assumption is no longer satisfactory for the light-weight manipulators. The effects of flexibility of light-weight manipulators have been an active research area in recent years. A new approach to correct the quasi-static position and orientation error of the end-effector of a manipulator with flexible links is studied in this project. In this approach, strain gages are used to monitor the elastic …

Measurement Of The Nonsteady Flow Field In The Opening Of A Resonating Cavity Excited By Grazing Flow, Hans R. Graf, William W. Durgin

Office of the Provost Scholarship

Flow past the opening of a cavity can excite acoustic resonance. The periodic velocity field in the region of the cavity opening has been measured for various flow conditions and the vorticity distribution has been computed from the measured data using numerical differentiation. The results indicate that the shear layer rolls up into discreet vortices, which travel across the cavity opening. Two resonances were found. The first is characterized by a single vortex being present and results in the greatest amplitude. The second is characterized by the presence of two vortices which excite a distinct but lesser amplitude resonance. As …

Wobbling Gear Drivetrain For Cordless Screwdriver, David K. Kedrowski, Scott P. Slimak

Honors Theses

Manufacturers of cordless screwdrivers use two planetary gear trains in series to reduce speed and multiply torque from a small electric motor. Alternately, a nutating gear drivetrain has the potential to create comparable speed reductions and torque multiplications. To apply nutating gear theory to a cordless screwdriver drivetrain, a study of spur gears, planetary gear reducers, bevel gears, and the theory of nutation was undertaken. Finally, a nutating design was proposed. The advantages of a nutating gear drivetrain over a conventional planetary gear train include: a decreased number of drivetrain parts, an ability to use lower-strength gear materials, a higher …

The Influence Of Reynolds Number And Atmospheric Effects On Aircraft Wake Vortices Near The Ground, Zhongquan Charlie Zheng

Mechanical & Aerospace Engineering Theses & Dissertations

Aircraft wakes represent potential hazards which can control aircraft spacing and thus limit airport capacity. Wake vortex trajectories and strengths are altered radically by interactions with the ground plane and by atmospheric conditions. This work has been concerned with developing more accurate numerical predictions. A two-dimensional, unsteady numerical-theoretical study is presented which has included viscous effects, the influence of stratification, crosswind and turbulence on vortex behavior near the ground plane, using a vorticity-streamfunction formulation.

A two-parameter perturbation procedure has been developed which uses analytic solutions for the initial flow field to accommodate the ground effect region in the numerical simulation. …

A Study Of The Interface Between A Turbulent Boundary Layer And The Irrotational Free Stream, Shih-Chao Lin

Mechanical & Aerospace Engineering Theses & Dissertations

A mathematical model has been developed to simulate the events which occur at the interface between a turbulent boundary layer and the irrotational free stream. By assuming the streamwise velocity component of this interface to be constant and that the interface is uncontorted initially, the solution to the equations of motion is used to derive the position functions of a point element on the interface. This analysis is restricted to a fully developed incompressible turbulent boundary layer with zero pressure gradient. Vertical velocity disturbances which are periodic in the spanwise direction and restricted to small streamwise domains are assumed.

The …

Effects Of Radiative Interactions In Molecular Gases Under Local And Nonlocal Thermodynamic Equilibrium Conditions, Manoj Kumar Jha

Mechanical & Aerospace Engineering Theses & Dissertations

Basic formulations, analyses, and numerical procedures are presented to investigate radiative heat interactions in diatomic and polyatomic gases under local and nonlocal thermodynamic equilibrium conditions. Essential governing equations are presented for both gray and nongray gases. Information is provided on absorption models, relaxation times, and transfer equations. Radiative flux equations are developed which are applicable under local and nonlocal thermodynamic equilibrium conditions.

The problem is solved for fully developed laminar incompressible flows between two parallel plates under the boundary condition of a uniform surface heat flux. For specific applications, three diatomic and three polyatomic gases are considered. The results are …

Analysis Of Pultrusion Processing For Long Fiber Reinforced Thermoplastic Composite System, Wen Tso

Mechanical & Aerospace Engineering Theses & Dissertations

Pultrusion is one of the composite processing technology, commonly recognized as a simple and cost-effective means for the manufacturing of fiber-reinforced, resin matrix composite parts with different regular geometries. Previously, because the majority of the pultruded composite parts were made of thermosetting resin matrix, emphasis of the analysis on the process has been on the conservation of energy from various sources, such as heat conduction and the curing kinetics of the resin system. Analysis on the flow aspect of the process was almost absent in the literature for thermosetting process. With the increasing uses of thermoplastic materials, it is desirable …

An Analysis Of The Response Of A Buckled Beam With Fixed Ends To An Harmonic Base Excitation Using The Finite Element Method, Peter John O'Donoghue

Mechanical & Aerospace Engineering Theses & Dissertations

A finite element formulation is developed to analyze the large deflection vibration of a buckled isotropic beam. The beam is buckled mechanically by an applied end displacement, and the dynamic loading is derived from the forced periodic base motion. The principle of virtual work is used to derive the system equations of motion. A Newton-Raphson iteration routine modified for the case of an applied end displacement is used with the incremental equations of motion to determine static deflection. The 0l time numerical integration algorithm is applied to the system of equations of motion in physical coordinates to determine dynamic response …

Robust Control Of Nonlinear Multibody Flexible Space Structures, Atul G. Kelkar

Mechanical & Aerospace Engineering Theses & Dissertations

A generic nonlinear math model of a multibody flexible system is developed. Asymptotic stability of such systems using dissipative compensators is established. It is proved that, under certain conditions, this class of systems exhibit global asymptotic stability under dissipative compensation. The dissipative compensators considered are static as well as dynamic dissipative compensators. The stability proofs are based on passivity approaches, Lyapunov methods, as well as a key property of such systems, i.e., skew-symmetricity of certain matrix. The importance of the stability results obtained is that the stability is robust to parametric uncertainties and modeling errors.

For static dissipative compensators, it …

Mitigation Of Shock Waves In A Cylindrical Tunnel By Foam, Grant W. Fondaw

Theses and Dissertations

This study investigated the effectiveness of foam linings in mitigating shock waves in tunnels. A polyurethane foam liner of varying density, crush strength and thickness was modeled inside a 1 meter radius tunnel and an explosion of 1.25 kg of plastic explosive was simulated. Using CTH, an Eulerian- Lagrangian hydrodynamics code from Sandia National Laboratories, the overpressures were computed and compared graphically to determine the effect of varying each foam parameter. The walls of the tunnel consisted of a perfectly reflecting boundary, and in some cases, a foam liner. Low density foam provided the most shock attenuation. with a 20 …

Analysis Of A Band-Saw, Suat Ali Ozsoylu

Dissertations

The solution for the transverse oscillations of a band-saw is determined. Two different models are treated: a fourth-order model and a second-order model. The response characteristics for both models are determined using Laplace transformation. To obtain the inverse Laplace Transform for the fourth-order model, it was necessary to fmd the frequencies by applying the Extended Lanczos Method in order to overcome the problem for computer overflow.

The limits of stability for both models are studied by plotting the eigenvalues against changing parameter values. Conditions for the onset of divergence and flutter instabilities, which need to be taken into account in …

Study Of Surface Properties Produced By Magneto-Plasma On Nitriding For Improving Wear Resistance, I-Tsung Shih

Dissertations

In this work a newly developed surface treatment process, Magneto-Plasma Ion Nitriding process, was developed and studied. This process was developed to increase durability and wear resistance of operational surfaces of different machine components.

In this study, orthogonal experimental analysis was used to develop, optimize, and select the process parameters. Coating layers were characterized and studied by using scanning electron microscopy(SEM), Auger electron spectroscopy(AES), and image analysis system. The influence of different process treatment parameters, such as temperature, nitrogen concentration, and magnetization, on the layers properties was studied. The mechanism of layer formation and bonding was proposed and a mathematical …

Reverse Engineering : An Evaluation Of Contact Technology And Application In Manufacturing Systems, Shailesh V. Jadhav

Theses

There are many instances where one-of-a-kind parts, such as prototypes or custom-built parts, need to be reproduced. When a Computer Aided Design (CAD) of an existing part is not available, reverse engineering is involved in recreation of such part. Currently, geometric measurements from the surface of a prototype are extracted manually and sent to a CAD system. It is typically time consuming, tedious, and potentially a source of error. This study outlines a methodology, for the development of a CAD model, rapid prototype, and subsequently manufacturing of the part. The method developed uses a contact technique to extract 2-D or …

Trouble Shooting In Plastic Injection Molding Machines, Zafar Kamal

Theses

The purpose of this thesis is to find the solution of those problems which occur during plastic injection molding process. Molding cycle problem analysis is an important field in plastic injection process. It is very necessary to catch the problems during operation. Therefore on the basis of research trouble shooting criteria is prepared.

Good quality control is an essential feature for finding any sort of fault. Quality control is associated with each and every step of operation to maintain the required shape and surface finishing.

Most of the molding problems are solved by varying the machine conditions and by changing …

Stepwise Reduction And Approximation Method For Performance Analysis Of Generalized Stochastic Petri Nets, Jinming Ma

Theses

This thesis delves into the performance analysis of generalized stochastic Petri net (GSPN) model by using an approximation method: the Stepwise Reduction and Approximation (SRA) Method. The key point is that we are able to analyze a subnet in isolation by keeping its token flow direction and its sub-throughput equivalent with all the possible tokens entering into the subnet. The thesis first defines various kinds of potentially reducible subnets, subnet selection rules, approximation subnet construction rules, and reduction evaluation rules. Then corresponding to the possible subnets, the approximation method is used stepwisely until the interested measures are found with the …

Forward Kinematics Solution Of A Special Class Of General Stewart Platforms, Jian Li

Theses

A Stewart platform is a fully parallel, six-degree-of-freedom manipulator mechanism. A platform manipulator has a fixed platform acting as base, a mobile platform on which end-effector is mounted, and in-parallel kinematics chains (legs) between the two platforms. Although some direct position kinematics solutions for Stewart platforms of simplified geometry have been represented, to the best of our knowledge, no close-form direct kinematics solution for the general Stewart platform is available yet.

A common feature of six-degree-of-freedom Stewart platform of simplified geometry is the use of pairs of concentric ball joints. Due to inevitable manufacturing and assembly errors, practically there are …

Motorized Throttle Plate, John D. Crawford

Opportunities for Undergraduate Research Experience Program (OURE)

The objective of this project was to develop a throttle plate mechanism that can be used to simulate transient engine operation. This throttle plate was designed so as to regulate the quantity of air flow entering a Port Fuel Injected (PFI) spark ignition engine prior to the combustion of the fuel-air mixture. The throttle plate is linked to a data acquisition system in order to study the port fuel injection characteristics of the fuel-air mixture. This data acquisition system links the throttle plate angular position information to data obtained using a nonintrusive laser based diagnostic technique, therefore enabling the study …

Catalysis Of Charcoal Emissions, James M. Horak

Opportunities for Undergraduate Research Experience Program (OURE)

This paper is about the development of a system to reduce the emissions of charcoal kilns with the catalyst from automotive catalytic converters. This device, called the charcoal kiln emissions oxidizer (CKEO), was designed and fabricated to meet the goal of a cost effective means to reduce the carbon monoxide and hydrocarbon emissions from charcoal kilns. Testing of the CKEO was never carried out as a test site could not be secured by this writing. The need for the CKEO, the theory behind it, and a procedure to test it are presented.

Damage Assessment Of Composite Structures With Embedded Optical Fibers, Peter E. Hackett

Opportunities for Undergraduate Research Experience Program (OURE)

One of the important features of smart composite structures is their capability to observe their own performance for proper functioning and self-diagnostic purposes. The low velocity impact damage of composite structures (matrix cracking, fiber breakage, delamination, etc.) is often difficult to detect visually and can significantly reduce the strength of the structure. The objective of this research is to develop a technique for fabricating composite laminates that will facilitate the embedment of optical fibers. Composite test specimens will be fabricated in the composite material laboratory. The fabrication of composite laminates with a health monitoring and damage assessment system capable of …

Performance Analysis For The Ccn Collection Apparatus, Deborah K. Bircher

Opportunities for Undergraduate Research Experience Program (OURE)

This paper concerns the performance testing of a system to collect and chemically analyze cloud condensation nuclei (CCN). These are the atmospheric particles which nucleate cloud drops.

The air is humidified by passage through the "haze chamber", consisting of parallel vertical plates that are covered with cotton cloth and are kept wet by water supplied at the top edge. The plates are adiabatic , and should equilibrate in temperature at the wet bulb temperature of the incoming air. Measurements of the plate temperature with eighty thermocouples indicate behavior consistent with theory.

Another part of the system is called the CFD …

Active Buckling Control Of Composite Plates, Bradley Wayne Gentelin

Opportunities for Undergraduate Research Experience Program (OURE)

The objective of the research project is to investigate the feasibility of using the rapidly growing technology of smart materials in actively controlling the buckling of laminated composite plates. Advanced composite structures are susceptible to structural instabilities under compression loadings, and the proper control of such instabilities is essential to the effective performance of the structures. The focus of the research activity is to perform an experimental study of using embedded piezoelectric materials for enhancing the critical buckling loads of laminated composite plates. The forces induced by the piezoelectric actuators under the applied voltage fields will be used to counterbalance …