Engineering Commons^™

On Local Stresses And Spring Constants Of Pipe-Nozzle Connection, Hson-Chih Sun

Dissertations

This thesis presents a comprehensive study of local stresses and spring coefficients of pipe with a nozzle connection, analyzed by the finite element method (FEM). Six types of loading are discussed: radial force, circumferential moment, longitudinal moment, circumferential shear force, longitudinal shear force, and torsional moment.

For the local stresses, the bending and membrane stress factors due to each of these loadings are presented in a series of plots with various gamma (piping radius/thick-ness) and beta (nozzle radius/pipe radius) values. These stress factors will readily replace those previously published in WRC No. 107. This work not only gives more accurate …

Characterization Of Material Removal In The Course Of Abrasive Waterjet (Awj) Machining, Yu Yang

Theses

The objective of this study is to develop a practical procedure for prediction of the results of abrasive waterjet (AWJ) machining. The first stage of the study involves the development of the technique for prediction of the rate of material removal in the course of abrasive waterjet (AWJ) machining. A new parameter, Exergy Distribution Density (EDD), is introduced and used in order to characterize the cutting conditions. EDD, determined as the kinetic energy of particles delivered to a unit length of the generated surface, is the function of diameters of the sapphire nozzle (Dn) and the focusing tube (Dc), the …

A Study Of Machining Parameters To Optimize Surface Finish In Metal Cutting Through Cnc, S. Waseem H. Zaidi

Theses

The purpose of this thesis is to find the relationship between surface finish and machining parameters. A series of experiments have been performed at shop floor of NJIT, on MAZAK(CNC turning center), using two different cutting tool materials(high speed steel and cemented carbide) and a workpiece of Aluminium. The results have been then evaluated and analyzed to see the effects of various combinations of cutting conditions, that is, feed, speed, and depth of cut. Recommendations have been made on the basis of analysis to estimate the minimum and maximum values of surface roughness with respect to the cutting conditions for …

Finite Element Analysis Of Torsional Concentric Composite Shaft Using Isoparametric Circular Element, Yee-Haur Wong

Theses

Finite Element Method is used to analyze the concentric composite material shaft subjected to torsion. Isoparametric circular ring element has been formulated to solve the one-dimensional problem. An intermaterial element at the interface has been developed to accomodate the changing modulus of rigidity.

Solutions of Prandtl's stress functions are used to compute shear stresses and torque in the composite shaft. Results of torque of the composite shaft are established using convergence tests of homogeneous solid and hollow shafts. Good agreement with classical solutions are obtained for homogeneous solid and hollow shafts.

A Torsional Concentric Composite Chart has been developed showing …

The Planet Janitor: A Symbol Of Global Concerns, Florida Solar Energy Center, Public Information Office

FSEC Energy Research Center®

Meet the Planet Janitor. A kindly, yet determined gentleman. He works at the Florida Solar Energy Center where he is a spokesman for energy-related issues. He illustrates the need to sweep up all environmental messes we've made. He reminds us to maintain our home - Planet Earth. He dramatizes our role as custodians of our children's inheritance. He knows and he shows how the individual can make a difference.

Renewable Energy Activities For Middle Grades, Florida Solar Energy Center, David Lahart

FSEC Energy Research Center®

The Florida Solar Energy Center (FSEC) is a research and education arm of the State University System hosted by the University of Central Florida. The Florida legislature established FSEC in 1974 to conduct research in alternative energy technologies, to ensure the quality of solar energy equipment sold in Florida, and to educate people about renewable energy technology.

One method of disseminating research results has been through teacher education programs and the development of instructional materials. FSEC-developed materials are designed to teach science and social studies research methods and/or process skills. The units have been field-tested and correlated with student performance …

Composite Structure Ultimate Strength Prediction From Acoustic Emission Amplitude Data, James Lewis Walker Ii

Master's Theses - Daytona Beach

The acoustic emission (AE) given off by a structure as it is stressed provides a passive means to characterize flaw growth activity in complex structures. This thesis demonstrates how the qualitative analysis of AE data can be refined to provide a quantitative tool for predicting the ultimate strength of composite tensile test specimens. From an original sample set of only six specimens, a multivariate statistical analysis was used to generate an ultimate strength prediction equation. The variables of the multivariate statistical analysis were obtained through the mathematical modeling of the specimen’s AE amplitude distributions produced during proof testing. Ultimate strengths …

Sahkti Limited, Sanjoy Goel

IIMB Management Review

No abstract provided.

Damping Of Layered Beams With Mixed Boundary Conditions, Eugene T. Cottle

Theses and Dissertations

For many years, viscoelastic materials have been used in damping treatments to control vibration. In order to optimize a damping treatment for maximum damping, a design engineer must be able to predict frequencies of vibration of damped normal modes and loss factors as a function of the design parameters. Theoretical models of layered beams have been developed, but to date, exact solutions have assumed boundary conditions to be the same for all layers. In this thesis, equations of motion for a damped, layered beam are solved for the longitudinal displacement of both elastic layers, as well as the lateral displacement …

Radon Pressure Differential Project; Phase Ii Infiltration, Florida Solar Energy Center, James Cummings

FSEC Energy Research Center®

Testing has been done on 50 central Florida homes to assess and characterize house infiltration rates in new (age five years or less) Florida homes. These 50 were drawn randomly from a sample of 70 homes which had been previously tested to determine house airtightness, air distribution system leakage, and pressure differentials. The 50 homes had an average airtightness of 7.31 air changes per hour at 50 Pascals (ACH50). Significant leaks were found in the ductwork in a majority of homes tested, both on the supply and return sides of the air handler. When the air distribution system was sealed …

Radon Pressure Differential Project, Phase I, Florida Solar Energy Center, James Cummings

FSEC Energy Research Center®

Testing has been done on 70 central Florida homes to assess and characterize pressure differentials in new (age five years or less) Florida homes. Blower door testing was done to determine house airtightness and air distribution system leakage. The 70 homes had an average airtightness of 7.23 air changes per hour at 50 Pascals (ACH50). Significant leaks were found in the ductwork in a majority of homes tested, both on the supply and return sides of the air handler. When the air distribution system was sealed off, house ACH50 decreased to 6.42, indicating that 11.2% of the house leak area …

Decomposition Of Measured Contours Into Geometric Features For Dimensional Inspection, Devaraj Rajkumar

Dissertations and Theses

Image processing systems used in Vision Assisted Dimensional Inspection usually output a set of boundary pixels representing the part edges. This boundary information must be divided into several subsets representing the various edges of the actual object, so that comparisons with the nominal part can be made.

The purpose of this project is to devise a method to divide the set of pixels obtained from the image processing system into subsets of pixels. Each of these subsets represent an edge in the contour of the actual object. This method must also detect transition points between the adjacent features. This project …

Advanced Space Design Program, William W. Durgin, Francis C. Lutz

Office of the Provost Scholarship

Worcester Polytechnic Institute's Advanced Space Design (ASD) Program provides project-based design experiences that combine a highly motivating, need-to-know experience with an integrative capstone design that draws on the know-how of practitioners in the profession. Mechanical engineering students work with their counterparts in electrical, chemical, and civil engineering to develop integrated packages of experiments to be conducted in the micro-gravity environment of space.

The Dynamics Of Bicycling : An Analytical And Experimental Investigation To Determine The Principles Of Design, Sylvester Yen

Theses

Bicycles have existed in working order for a century. They are mechanical products whose dynamic characteristics are highly nonlinear. This has to some extent prevented detailed analysis and for the most part design has been made from practical experience. The advent of computers has markedly changed the techniques and procedures used to calculate the performance of a bicycle. Bicycling began long ago, and since the first bicycle was demonstrated, bicyclists, scientists and engineers have designed thousands of different bicycles considering safety, comfort to ride and ease of control. Nonetheless, nobody claims to fully understand bicycling. If the fundamental principles exist, …

An Assessment Of Just-In-Time Manufacturing, Ronald E. O'Meara

Graduate Research Papers

Manufacturing of materials into useable products has changed dramatically since the Industrial Revolution. The United States dominated the manufacturing arena until the early 1970s. After that period, efforts of global competitors in such areas as quality control and productivity, started to surpass the efforts made by the United Stated in these same areas. For the first time, U.S. manufacturers started sensing the pressure of competition. The United Stated is using its competitive advantage over other nations in the manufacturing segment. Part of this loss is a result of the way the U.S. manufacturers are conducting their business. A larger part …

Ole Miss Engineer 1990

Ole Miss Engineer

No abstract provided.

The Effectiveness Of Viscoelastic Damping Treatments On A Flexible Manipulator Subjected To Torsional Loads, Leah L. Remias

Mechanical & Aerospace Engineering Theses & Dissertations

The advent of new technology has led to an increasing number of missions in space. The space shuttle Remote Manipulator System (RMS) is a lightweight flexible manipulator currently used in NASA space missions. The future role of the RMS and similar flexible manipulators may include in-space construction and assembly tasks. Because these tasks require precise motion and short settling time of the end-point oscillations, effective vibration control schemes are being investigated.

Passive damping techniques have shown to provide a considerable amount of damping in controlling flexural vibrations. In this research passive damping via constrained viscoelastic damping treatments is explored as …

Development Of A Perturbation Generator For Vortex Stability Studies, John Edward Riester Jr.

Mechanical & Aerospace Engineering Theses & Dissertations

Theory predicts vortex instability when subjected to certain types of disturbances. It was desired to build a device which could introduce controlled velocity perturbations into a trailing line vortex in order to study the effects on stability. A perturbation generator has been designed and manufactured which can be attached to the center-body of an airfoil type vortex generator. Details of design tests and manufacturing of the perturbation generator are presented. The device produced controlled perturbations with frequencies in excess of 250 Hz. Preliminary testing and evaluation of the perturbation generator performance was conducted in a 4 inch cylindrical pipe. Observations …

Design For Manufacturing Of Mechanical Power Transmission Shafts, Tamer Mohamed Wasfy

Archived Theses and Dissertations

No abstract provided.

Space Structures: Issues In Dynamics And Control, H. Benaroya, Mark L. Nagurka

Mechanical Engineering Faculty Research and Publications

A selective technical overview is presented on the vibration and control of large space structures, the analysis, design, and construction of which will require major technical contributions from the civil/structural, mechanical, and extended engineering communities. The immediacy of the U.S. space station makes the particular emphasis placed on large space structures and their control appropriate. The space station is but one part of the space program, and includes the lunar base, which the space station is to service. This paper attempts to summarize some of the key technical issues and hence provide a starting point for further involvement. The first …

Measurement Of Thermal Noise In Condenser Microphones In A Vacuum-Isolation Vessel, Kim Chi Thi Ngo

Electrical & Computer Engineering Theses & Dissertations

The electrical noise generated by thermal agitation of the air molecules impinging upon the membrane of a condenser microphone and from its associated preamplifier has been studied analytically and experimentally over a wide bandwidth. These background noise levels constitute one of the most important specifications of a microphone for they determine the lowest sound pressure that can be detected. Therefore, a new method for measuring the thermal agitation noise within a bandwidth of 1-25600 Hz has been developed. The theoretical and experimental measurements of thermal agitation noise in a condenser microphone by enclosing the microphone in a vessel which is …

Integrated Control Of Thermally Distorted Large Space Antennas, Robert H. Tolson

Mechanical & Aerospace Engineering Theses & Dissertations

Studies on controlling the thermal distortion of large space antennae have generally investigated a single orbital position and have optimized actuator locations based on minimizing the RMS surface deviation from the original parabolic shape. One study showed the benefits of directly using far zone electric field characteristics as the performance measure; but, this approach resulted in a nonlinear programming problem. The objective of the current study is to develop an approach to designing a control system that (1) recognizes the time dependence of the distortion and (2) controls variables that are directly related to far field performance in a quadratic …

Edge Matching Of Aerial Scenery Using Fourier Descriptors, Ananth Kittappa

Theses

In this report an integrated method of classifying aerial images as related to photo stereo grammetry is discussed. In this method, an investigation of Fourier descriptors as features for the edge matching approach is carried out. The efficient calculation of the Fourier Descriptors is made possible by applying the polygonal approximation method to the original edges. In order for the features to be invariant to rotation, scaling and starting point shift, a normalization technique is adopted. Initially the Fourier Descriptors are tested for synthesized test datasets and it was proved that the variances of the Normalized Fourier Descriptors was a …

Characteristic Shape Recognition With Fuzzy Dustering, Kalpesh J. Patel

Theses

The problem of shape detection has been treated as one of clustering. A fuzzy-shell clustering(FSC) has been formulated as non linear least squares with fuzzy memberships as weights. An improved FSC algorithm has been proposed based on this formulation to partition the input feature vectors into hyper-spheres. To illustrate the usefulness of improved FSC we have provided numerous examples in 2-D space. The idea has been extended to fuzzy ellipsoidal-shell clustering (rESC). A FESC algorithm has been proposed to partition the input feature vectors into ellipsoidal patterns. To substantiate our claims regarding usefulness of this algorithm we have provided many …

Finite Element Analysis Of Thermal Stresses In Semiconductor Devices, Joachim Karl Wilhelm Duerr

Dissertations and Theses

The failure of integrated circuit due to Silicon fracture is one of the problems associated with the production of a semiconductor device. The thermal stresses, which result in die cracking, are for the most part induced during the cooling process after attaching the die with Gold-Silicon solder. Major factors for stress generation in material systems are commonly large temperature gradients and substantial difference in coefficients of thermal expansion.

This research covers the thermal stresses introduced upon cooling a composite Silicon device. A transient thermal analysis has been performed to determine the temperature gradients. The stress distribution has been investigated. For …

Improving The Throughput Of Plasticating Extruders : Measurement Of The Interparticulate Friction Coefficient For Polymeric Particulates With Circular And Profiled Cross Sections, Aiping Chen

Theses

This thesis deals with the coefficient of friction between individual polymeric pellets, the interparticulate friction coefficient (IPFC). It has been measured using a shear cell for a wide variety of circular and profiled cross?section pellets for a variery of polymeric materials. First, the thesis explains the reasons why it is desirable to enhance the IPFC based on the melting mechanisms in a single screw plasticating extruder. By making pellets with profiled cross?section pellets, the IPFC is greater than for pellets of circular cross?section. Second, it describes the test apparatus for measuring the IPFC and the method for calculating the IPFC. …

Nondestructive Detection Of An Undeserable Metallic Phase, T1, During Processing Of Alumnum-L Thumalloys, Otto Buck, David J. Bracci, David C. Jiles, Lisa J.H. Brasche, Jeffrey E. Shield, Leonard S. Chumbley

Department of Mechanical and Materials Engineering: Faculty Publications

A method is disclosed for detecting the T1 phase in aluminum-lithium alloys through simultaneous measurement of conductivity and hardness. In employing eddy current to measure conductivity, when the eddy current decreases with aging of the alloy, while the hardness of the material continues to increase, the presence of the T1 phase may be detected.

Electrical Use, Efficiency, And Peak Demand Of Electric Resistance, Heat Pump, Desuperheater, And Solar Hot Water Systems, Florida Solar Energy Center, Timothy Merrigan

FSEC Energy Research Center®

Eighty single family residences in Florida were monitored for two years in order to collect data on water heating electrical energy consumption, efficiency, and time-of-day demand. The homes were divided into equally sized samples of four different water heating systems: conventional electric resistance, heat pump, desuperheater and solar hot water systems. Electrical consumption for electric resistance water heaters averaged 8.3 kWh per day in Florida with an average water heating system efficiency of 82%. Desuperheaters used an annual average of 7.4 kWh per day at an annual system efficiency of 110% and heat pump water heaters used 6.1 kWh per …

Investigation Of Mixing Characteristics Of A Lox Injector Operating At Non-Ideal Thermodynamic Conditions, W. Wei

Mechanical & Aerospace Engineering Theses & Dissertations

The mixing characteristic of a liquid oxygen (LOX) injector operating under nonideal thermodynamics conditions are analyzed. Oxygen, in supercritical state, is injected into a high pressure airstream flowing through a narrow annulus region of a hypersonic wind tunnel. The objective of the present study is to investigate conditions that would help produce a uniform profile of oxygen concentration at the end of a diverging mixing channel, located downstream of the injector section. Uniformity of oxygen concentration profile is critical to combustion processes that occur downstream of the LOX injector section.

The coupled velocity, temperature, oxygen concentration and enthalpy fields are …

Use Of A Generalized Set Of Variables In Fluid Flow Calculations, Pawel Chwalowski

Mechanical & Aerospace Engineering Theses & Dissertations

In fluid flow calculations, a set of generalized field variables is used to replace the more conventional choice of either the conserved variables, or the primitive variables. This generalized set of variables represents an infinite number of possible choices for the specific set of field variables. For algorithms of both the implicit and explicit type, the resulting effect of a change in field variables on a steady-state flow solution is in general relatively small. However, for implicit algorithms, a consistent linearization with respect to the new variables results in dramatic changes in the overall matrix conditioning of the linear systems …