Engineering Commons^™

A Market Profile Of Epc Foundries In North America, Jennifer D. Ballacchino

Graduate Research Papers

The purpose of this study is to discover what successes foundries are having with the EPC process and promote these successes. The EPC casting industry can use this information to encourage adoption of the process and thereby stimulate component conversion and application. Information gathered during this study will be consolidated into promotional materials about the EPC process. The materials will provide information to individuals in the industry, including foundries, suppliers and, most importantly, designers. Through sharing of information about the process, it can be better understood and acceptance may increase.

Studies On Nonequilibrium Phenomena In Supersonic Chemically Reacting Flows, Rajnish Chandrasekhar

Mechanical & Aerospace Engineering Theses & Dissertations

This study deals with a systematic investigation of nonequilibrium processes in supersonic combustion. The two-dimensional, elliptic Navier-Stokes equations are used to investigate supersonic flows with nonequilibrium chemistry and thermodynamics, coupled with radiation, for hydrogen-air systems. The explicit, unsplit MacCormack finite-difference scheme is used to advance the governing equations in time, until convergence is achieved.

For a basic understanding of the flow physics, premixed flows undergoing finite rate chemical reactions are investigated. Results obtained for specific conditions indicate that the radiative interactions vary substantially, depending on reactions involving HO$\sb2$ and NO species, and that this can have a noticeable influence on …

Study Of Algebraic Reynolds Stress Models For The Computation Of Secondary Motion In Channels, Tomas Chylek

Mechanical & Aerospace Engineering Theses & Dissertations

A three-dimensional computer code for solving Reynolds equations of turbulent flow at high Reynolds numbers in generalized curvilinear coordinates is used to study the engineering applications of several variants of linear and nonlinear second moment algebraic Reynolds stress models based on pressure-strain correlation of Launder, Recce and Rodi (1975) and Speziale, Sarkar and Gatski (1991). A new form of algebraic Reynolds stress equation in generalized curvilinear coordinates is derived based on simplification of Reynolds stress transport equations. Two implicit and two explicit implementations are explored in three different geometries of straight channel flows. The predictions of secondary motion driven by …

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 …

Study Of Single-Fiber Fiber Optic Lever Microphone, Trung Duc Nguyen

Electrical & Computer Engineering Theses & Dissertations

Fiber optic sensors are widely used in today's technological applications, providing many advantages that conventional sensors lack. In particular, there is a demand in hypersonic applications to develop microphones to measure acoustic pressure that performs in high temperature and noisy surroundings. This thesis analyzes fiber optic lever microphones (FOLM), since they perform at high temperatures. An FOLM system is an intensity modulated sensor, which is simple to implement and is small in size. Two models of the FOLM have been fabricated and calibrated. The first model uses a seven-element fiber array while the second uses a single-fiber to transmit and …

Single Scheduling Problem With Dependent Setup Cost, Mohamed Mahmoud Zaki

Archived Theses and Dissertations

No abstract provided.

Finite Element Analysis For An Involute Spur Gear Noise Excitation By Impact Effects, Wenbeen Li

Electronic Theses & Dissertations

The purpose of this study includes (1) to identify the relationship between the impact loads or backlash and the sound field pressure of impact direct noise of meshing gears, (2) to show that impact whether or not the impact direct noise contributes to the noise of overall gear system, and (3) to demonstrate how impact direct noise can be predicted. The method used to predict was finite element analysis and numerical solution. This research presents the analytical model of impact direct noise prediction for meshing gear teeth based on the data that the tooth vibration and surface are known by …

Variable Structure End Point Control Of A Flexible Manipulator, Shailaja Chenumalla, Sahjendra N. Singh

Electrical & Computer Engineering Faculty Research

We treat the question of control and stabilization of the elastic multibody system developed in the Phillips Laboratory, Edwards Air Force Base, California. The controlled output is judiciously chosen such that the zero dynamics are stable or almost stable. A variable structure control (VSC) law is derived for the end point trajectory control. Although, the VSC law accomplishes precise end point tracking, elastic modes are excited during the maneuver of the arm. A Linear stabilizer is designed for the final capture of the terminal state.

Boundary Layer Influences On The Subsonic Near-Wake Of A Family Of Three-Dimensional Bluff Bodies, Charles Willliam Alcorn

Mechanical & Aerospace Engineering Theses & Dissertations

A study is reported on subsonic bluff body near-wake flows. It has been determined that one family of bluff bodies, namely slanted-base ogive cylinders, can experience either a closed recirculating near-wake, or a longitudinal vortex near-wake depending on the base slant-angle and the Reynolds number. This suggests a dependence of near-wake parameters on the state of the boundary layer ahead of separation. This report addresses the influence of the boundary layer on the near-wake of slanted-base bluff bodies. Experiments were conducted in two facilities, the 6-inch Magnetic Suspension and Balance System (MSBS) at NASA Langley Research Center and the Old …

Fiber Enhanced Viscoelastic Damping Polymers And Their Application To Passive Vibration Control, Houchun Xia

Mechanical & Aerospace Engineering Theses & Dissertations

A new composite damping material is investigated, which consists of a viscoelastic matrix and high elastic modulus fiber inclusions. This fiber enhanced viscoelastic damping polymer is intended to be applied to light-weight flexible structures as surface treatment for passive vibration control. A desirable packing geometry for the composite material is proposed, which is expected to produce maximum shear strain in the viscoelastic damping matrix. Subsequently, a micromechanical model is established in which the effect of fiber segment length and relative motion between neighboring fibers are taken into account. Based on this model, closed form expressions for the effective storage and …

Vibration Suppression Of Beam Structures Traversed By Multiple Moving Loads Using A Damped Absorber, Y.H. Lin, C.H. Cho

Journal of Marine Science and Technology–Taiwan

This paper deals with the dynamic analysis of a simply supported beam subjected to multiple discrete and distributed moving loads. Resonant vibration is observed for the support beam traversed by multiple discrete moving loads. A practical scheme is applied to reduce the excessive beam vibration to an acceptable range by using a damped absorber attached at the beam center. Lagrange's equation is used to formulated the system governing equation and Laplace transformation is applied to derive the dynamic responses for both the beam and the absorber, Various design parameters, such as the mass ratio, the tuning ratio, and the damping …

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 …

Formation Of Amorphous Cu-Zr Alloy Powder By Mechanical Alloying, T.R. Chen, P.Y. Lee

Journal of Marine Science and Technology–Taiwan

Amorphous Cux Zr100-x alloy powder has been synthesized in the range 20 ≦ x ≦ 80 by mechanical alloying mixtures of Cu and Zr powders. This range is larger than amorphous alloys produced by the vaporquenching technique. A mixture of amorphous and crystalline phases formed at the compositions of Cu10Zr90 and Cu90Zr10. Amorphous CuxZr100-x alloy powder also has been synthesized in the range 20 ≦ X ≦ 60 by mechanical alloying mixtures of intermetallic compound Cu9Zr2 and CuZr2 powders. The temperature and activation energy for crystallization of the MA Cu-Zr amorphous powders are higher than that for vaporquenched samples. The …

Second Law Analysis On Ejection Cooling System, S.P. Liaw, Y.H. Chang

Journal of Marine Science and Technology–Taiwan

Ejection cooling system is analyzed by the second law of thermodynamics in this study. It is mainly consisted of a boiler, an ejector, an expansion device, a condenser, and an evaporator. Special focus is stressed on the variation of exergy in each component. The working refrigerant received exergy from boiler and pump and cons umed in other parts of the system. The coefficients of performance based on both the first and the second laws are computed respectively and thus the changes of energy and exergy in each component of the system can be readily understood. In addition, the boiler temperature, …

Aluminum Electrodeposition From Room Temperature Molten Alcl3-Bpc Salt Bath, C.C. Yang, C.P. Chang

Journal of Marine Science and Technology–Taiwan

The characteristics of aluminum electrodeposited layer from an ambient temperature molten salt were discussed in this study. The experimental results indicated that it is possible to carry out aluminum electrodeposition on the surface of brass and stainless steel when binary AlCI3-8P C molten electrolysis were used. The morphology of the components, characteristics and images can be detected by SEM, Auger Analysis, X-ray diffraction analysis and electrochemical polarization curves. The denser and more adhesive electrodeposited aluminum layer can be achieved by chosing proper electrolyte components (AlCI3: BPC-acidic salt bath), current forms (D.C./pulse), current density, electrolytic time and other pretreatment. In addition, …

Numerical Study Of Spray Flame Characteristics, C.Y. Lin

Journal of Marine Science and Technology–Taiwan

A numerical method was considered to calculate spray flame structure and emissions characteristics. The turbulence fluctuation was predicted using k-e-g and algebraic mixing-length-hypothesis (mlh) turbulence models. The numerical method was evaluated using a set of available experimental data. It is shown that this theoretical model predicts the data well in the near nozzle region and the predictions improve quantitatively along the axial distance. In comparing the turbulence models, the k-e-g model provides a better result for the varying-density flow of spray combustion.

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 …

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 …

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 …

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 …

Design And Development Of Flexible Manufacturing Cells - A Case Study, Behrouz Barzani

Theses

This paper covers the typical ills of American manufacturing companies and provides steps to selecting a flexible manufacturing cell(s) or system as a remedy. For that reason various definition of different types of flexibilities in manufacturing and the interrelationships between the several types have been examined. In addition, their purposes, means of obtaining them and some measurement and evaluations has been discussed. This was done to cover the basic but necessary requirements for understanding and selecting a flexible manufacturing system. Finally, the design process of a flexible system and its intuitive justification were discussed.

Geometric Dimensioning And Tolerancing A Tool For Concurrent Engineering, Tapan Kumar S. K. Jain

Theses

The concept of Concurrent Engineering recognizes an immediate need for a new design environment and technology and so requires extensive interdisciplinary cooperation and integration of diverse functions of a manufacturing organization such as marketing, design, manufacturing and finance. One of the key factors to achieve successful integration among the departments is better communication and it becomes imperative in cases of varying levels of communication needs, especially in interdepartmental cases.

Concurrent Engineering is a philosophy which provides certain benefits. There are various tools and methods available for implementation of Concurrent Engineering concepts. One of the tools is Geometric Dimensioning & Tolerancing …

A Simulation Of A Monitoring And Alarm System In An Energy Management System, Hui-Jen Liu

Theses

This is a simulation for an energy system's monitoring and alarm and working under KEE's environment. Because of KEE's powerful capabilities, we can monitor and get warning signals from several active windows that we attaching them from KEE's system knowledge base to our source code.

It is very convenient for us to set every member of the energy system on an image panel. We can monitor the entire conditions of that member and get highlighted warning signals from its own image panel. Also we can initialize them by a kind of method-actuators windows if we want to restore the system.

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 …

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 …

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 …

A Study Of The Manufacturing Costs Of Grille And Side Screens On John Deere Tractors, John M. Beierschmitt

Graduate Research Papers

The problem discussed in this paper was the development of a process for the manufacture of a new, low cost, quality grille screen that previously had been made on conventional tooling, and now can not be made with the conventional process or tooling. The research comparison in this paper was done to show the financial advantage of this type of tooling.

An Examination Of The Labor Time Of A Robot Weld Cell, Chris S. Conrad

Graduate Research Papers

The purpose of this study was to determine the labor time differential, if any, of a robot weld cell as compared to manual welding methods. Also, the variability of labor time differential between part numbers was to be examined.

The results of the study was intended to assist future investment decision makers in maximizing the return on capital expenditures. It was proposed that the labor time differential determined by this study be applied to the future labor and overhead rates in determining the return on investment for a robotic weld cell purchase. The variability of labor time differential between part …