Aerospace Engineering Commons^™

Tip Vortex And Crenulation Effects In A Compressor Cascade With Moving Endwall, Barry W. St Germain

Theses and Dissertations

The effects of changing Reynolds number and flow coefficients on the velocity and pressure flow fields within a linear cascade with moving endwall were investigated in this experimental thesis. All flow field measurements were taken at a constant compressor blade tip gap clearance of 1.0 % chord and endwall speed of 318.6 ft/s (97.1 m/s), with flow coefficients of 0.40, 0.52, 0.62 and 0.72. All data acquisition occurred in a plane 23 % chord downstream of the trailing edge plane of the linear cascade. Hotwire probes determined the complete passage, three-dimensional fowled behind both crenulated and regular blade geometries. Vector …

Toward Development Of An Integrated Aerospace Power Doctrine, Toby G. Doran

Theses and Dissertations

This thesis discusses the state of the Air Force, decision making factors in the making of military doctrine, the definition of doctrine, Air Force doctrines today, new ways to develop doctrine, including models and hypothesis-research-analysis loops, space doctrine, control of space, space superiority and a call for aerospace power doctrine.

Progressive Failure Analysis Of Composite Panels, Stephen M. Spottswood

Theses and Dissertations

The objective of this research was to determine the physical response, including material failure, of a curved composite panel designed to resist transverse loading. The cause of the material failure, in the form of delamination, fiber and/or matrix failure, was determined through various criterion based on non-linear movement using a finite element analysis technique. Data generated both with and without the addition of progressive failure criteria, was compared with previously published experimental data, noting where the theory diverges from the experimental results. The inclusion of various failure criterion, to include maximum stress, Lee, and Hashin, provided a more realistic representation …

Joint Space Systems Operations Program, Robert J. Twiggs, Billy Smith

Robert "Bob" Twiggs STEM Education Collection

A PowerPoint Presentation created by Professor Bob Twiggs and Lt. Colonel Billy Smith on the "Joint Space Systems Operations Program" from February 8, 1999.

Opal Picosatellite Launcher, Robert J. Twiggs

Robert "Bob" Twiggs STEM Education Collection

A PowerPoint Presentation created by Professor Bob Twiggs titled "OPAL Picosatellite Launcher" from February 3, 1999.

Opal Launch Opportunity, Robert J. Twiggs

Robert "Bob" Twiggs STEM Education Collection

A PowerPoint Presentation created by Professor Bob Twiggs titled "OPAL Launch Opportunity" from February 3, 1999.

Emerald: A Low-Cost Spacecraft Mission For Validating Formation Flying Technologies, Robert J. Twiggs, Chris Kitts, Jon How

Robert "Bob" Twiggs STEM Education Collection

A PowerPoint Presentation created by Professor Bob Twiggs, Chris Kitts, and Jon How titled "EMERALD: A Low-Cost Spacecraft Mission for Validating Formation Flying Technologies" from January 19, 1999.

Fundamentals Of Linear State Space Systems, John Bay

Electrical and Computer Engineering Faculty Scholarship

This book addresses two primary deficiencies in the linear systems textbook market: a lack of development of state space methods from the basic principles and a lack of pedagogical focus. The book uses the geometric intuition provided by vector space analysis to develop in a very sequential manner all the essential topics in linear state system theory that a senior or beginning graduate student should know. It does this in an ordered, readable manner, with examples drawn from several areas of engineering. Because it derives state space methods from linear algebra and vector spaces and ties all the topics together …

Location Effects Of Passive Damping Material In Cross-Ply Laminates On Natural Frequency And Mode Shape, E. I. Elghandour, F. A. Kolkailah

Aerospace Engineering

This study presents an experimental investigation of the free vibration of cantilevered composite laminated plates with embedded passive damping material at different stages. A total of five composite laminated plates are considered. The lay-up sequences for the five composite laminated plates with and without two embedded layers of passive damping material are [90°/0°/90°/0°]_s, [90°/0°/90°/0°/d]_s, [90°/0°/90°/d/0°]_s, [90°/0°/d/90°/0°]_s, and [90°/d/0°/90°/0°]_s. The passive damping material employed is a 3M material, SJ-2015 ISD 112, with peak damping properties in the ambient temperature range of 32°F to 140°F. The composite material used is a carbon …

Emerald: A Low Cost Spacecraft Mission For Validating Formation Flying Technologies, Robert J. Twiggs, Jonathan How, Freddy Pranajaya, Bryan Palmintier

Robert "Bob" Twiggs STEM Education Collection

A PowerPoint Presentation created by Professor Bob Twiggs, Robert Twiggs, Jonathon How, Freddy Pranajaya, and Bryan Palmintier titled "EMERALD: A Low Cost Spacecraft Mission for Validating Formation Flying Technologies" from 1999.

Control Of The Air: The Enduring Requirement, Richard P. Hallion

United States Air Force: Publications

Throughout the military history of the twentieth century, the role of aerospace forces has become more predominant. Today, wars typically start, are prosecuted, and reach their decisive culminating point--whether surrender of a foe, agreement to a ceasefire, or the ceasing of combat operations--thanks to air action. Given these circumstances, to lose control of the air is to lose a war, particularly in an era (as we now are in since the end of the Cold War) when deployable overseas forces are small, and, thus, particularly vulnerable to the tremendous leverage an opponent gains by sudden and swift air attack. If …

Functional Interdependence And Product Similarity Based On Customer Needs, Daniel A. Mcadams, Robert B. Stone, Kristin L. Wood

Mechanical and Aerospace Engineering Faculty Research & Creative Works

In this paper, related product functions are determined for a group of approximately 70 consumer products. Using customer need data, a new matrix approach is introduced to identify these relationships. Techniques are then created for determining product similarity. These techniques are clarified and validated through three case studies, including beverage brewers and material-removal products. The results of these case studies are argued to have significant impact on design-by-analogy procedures, benchmarking methods, mass customization strategies and modular design. The paper concludes with a discussion of applications and related procedures for product development.

Frequency Domain Robustness Analysis Of Hopfield And Modified Hopfield Neural Networks, Jie Shen, S. N. Balakrishnan

Mechanical and Aerospace Engineering Faculty Research & Creative Works

A variant of Hopfield neural network, called the modified Hopfield network, is formulated in this study. This class of networks consists of parallel recurrent networks which have variable dimensions that can be changed to fit the problem under consideration. It has a structure to implement an inverse transformation that is essential for embedding optimal control gain sequences. Equilibrium solutions of this network are discussed. The robustness of this network and the classical Hopfield network are carried out in the frequency domain using describing functions

Emerald: University Built Satellite Extending Communications Experimentation For The Amateur Community, Robert J. Twiggs, Freddy Pranajaya

Robert "Bob" Twiggs STEM Education Collection

A published report by Bob Twiggs and Freddy Pranajaya titled "Emerald: University Built Satellite Extending Communications Experimentation for the Amateur Community" from 1999.

Opal: 2nd Ssdl Microsatellite, Robert J. Twiggs

Robert "Bob" Twiggs STEM Education Collection

A PowerPoint Presentation created by Professor Bob Twiggs titled "OPAL: 2nd SSDL Microsatellite" from 1999.

Space Systems Development Laboratory, Robert J. Twiggs

Robert "Bob" Twiggs STEM Education Collection

A PowerPoint Presentation created by Professor Bob Twiggs titled "Space Systems Development Laboratory" from 1999.

Space Systems Development Laboratory: Teach Systems Engineering, Robert J. Twiggs

Robert "Bob" Twiggs STEM Education Collection

A PowerPoint Presentation created by Professor Bob Twiggs titled "Space Systems Development Laboratory: Teach Systems Engineering" from 1999.

Emerald: Mission Statement, Robert J. Twiggs

Robert "Bob" Twiggs STEM Education Collection

The mission statement for the EMERALD Project from 1999.

Opal: A First Generation Microsatellite That Provides Picosat Communications For The Amateur Radio Community, Robert J. Twiggs, James Cutler, Greg Hutchinson, Jeffrey Williams

Robert "Bob" Twiggs STEM Education Collection

A research article written by Bob Twiggs, James Cutler, Greg Hutchinson, and Jeff Williams and published in 1999.

Studies Related To The Design Of A Magnetic Suspension And Balance System For An Ultra-High Reynolds Number Flow Facility, Oscar Magno Michael Gomeiz

Mechanical & Aerospace Engineering Theses & Dissertations

The basic design principles for a magnetic suspension and balance system applied to the test section of an ultra-high Reynolds number facility are defined. The design of the cross-sectional area to be used in the test section is analyzed. The parameters of the permanent magnet to be used in the model inside the test section are investigated. The testing of magnetic fields at the center of a test pipe and validation of data by computer finite element analysis is described with the purpose of finding common results. The performance of the magnet configuration is evaluated with relation to the magnetic …

Computational Modeling Of Airborne Noise Demonstrated Via Benchmarks, Supersonic Jet, And Railway Barrier, Moumen Idres

Mechanical & Aerospace Engineering Theses & Dissertations

In the last several years, there has been a growing demand for mobility to cope with the increasing population. All kinds of transportation have responded to this demand by expanding their networks and introducing new ideas. Rail transportation introduced the idea of high-speed trains and air transportation introduced the idea of high-speed civil transport (HSCT). In this expanding world, the noise legislation is felt to inhibit these plans. Accurate computational methods for noise prediction are in great demand.

In the current research, two computational methods are developed to predict noise propagation in air. The first method is based on the …

Setpoint Tracking Predictive Control In Chemical Processes Based On System Identification, Sinchai Chinvorarat

Mechanical & Aerospace Engineering Theses & Dissertations

A Kraft recovery boiler in a pulp-paper mill provides a means for recovery of the heat energy in spent liquor and recovery of inorganic chemicals while controlling emissions. These processes are carried out in a combined chemical recovery unit and steam boiler that is fired with concentrated black liquor and which produces molten smelt. Since the recovery boiler is considered to be an essential part of the pulp-paper mill in terms of energy resources, the performance of the recovery boiler has to be controlled to achieve the highest efficiency under unexpected disturbances.

This dissertation presents a new approach for combining …

Opal: Project Objectives & Development, Robert J. Twiggs

Robert "Bob" Twiggs STEM Education Collection

Project and development objectives for the OPAL Project from 1999.

Opal Update, Robert J. Twiggs

Robert "Bob" Twiggs STEM Education Collection

A PowerPoint Presentation created by Professor Bob Twiggs titled "OPAL Update" from 1999.

Environmental Performance Analysis Of Solid Freedom Fabrication Processes, Yanchun Luo, Zhiming Ji, Ming-Chuan Leu, R. J. Caudill

Mechanical and Aerospace Engineering Faculty Research & Creative Works

This paper presents a method for analyzing the environmental performance of solid freeform fabrication (SFF) processes. In this method, each process is divided into life phases. Environmental effects of every process phase are then analyzed and evaluated based on the environmental and resource management data. These effects are combined to obtain the environmental performance of the process. The analysis of the environmental performance of SFF processes considers the characteristics of SFF technology, includes material, energy consumption, processes wastes, and disposal. Case studies for three typical SFF processes: stereolithography (SL); selective laser sintering (SLS); and fused deposition modeling (FDM) are presented …

Hypersonic Drag And Heat Transfer Reduction Using A Forward Facing Jet, Benjamin Meyer, Harlan F. Nelson, David W. Riggins

Mechanical and Aerospace Engineering Faculty Research & Creative Works

A two-dimensional numerical study of the effects of a forward-facing jet located at the stagnation point of a blunt body on wave drag, heat transfer, and skin friction drag is presented for Mach 6.5 flow at 30 km altitude. The full Navier-Stokes equations are used with variable viscosity and thermal conductivity. It is shown that upstream injection can significantly modify the flow field. If the jet conditions are chosen properly, large reductions in drag and heat transfer can be obtained resulting in possible increases in the volumetric efficiency and static stability of aircraft and reductions in heating protection requirements for …

A New Reflection Free Boundary In Uniform Flow Using Mapped Infinite Wave Envelope Elements, Walter Eversman, Indranil Danda Roy

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Variable order mapped infinite wave envelope elements are developed for finite element modeling of acoustic radiation in a uniformly moving medium. These elements can be used outside of the near field as a non-reflecting boundary condition for computations on an infinite domain in which a radiating body is immersed in a moving medium. Mapped infinite wave envelope elements provide a boundary condition equivalent to stiffness, mass, and damping matrices appended to the inner mesh. A demonstration of the characteristics of the mapped infinite wave envelope elements is given in the context of acoustic radiation from a turbofan inlet for which …

Design, Optimization, And The Prototyping Of A Small Tuning-Fork Ultrasonic Piezoelectric Linear Motor, Daniel S. Stutts, James R. Friend

Mechanical and Aerospace Engineering Faculty Research & Creative Works

The design, optimization, and properties of a prototype small traveling-wave ultrasonic piezoelectric linear motor design are described. A method for optimizing the geometry of the motor to maximize its mechanical output for a given electrical input is described, as is the inherent properties of the design to maximize the motors durability and utilization of the piezoelectric material. Results from testing the motor demonstrate the design and indicate a maximum speed of 2.5 cm/s with a preload of 16 g due to an applied voltage of 80 V/RMS/ at an applied current of 15 mA.

Online Identification And Control Of Aerospace Vehicles Using Recurrent Networks, Zhenning Hu, S. N. Balakrishnan

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Methods for estimating the aerospace system parameters and controlling them through two neural networks are presented in this study. We equate the energy function of Hopfield neural network to integral square of errors in the system dynamics and extract the parameters of a system. Parameter convergence is proved. For control, we equate the equilibrium status of a "modified" Hopfield neural network to the steady state Riccati solution with the system parameters as inputs. Through these two networks, we present the online identification and control of an aircraft using its nonlinear dynamics.

Stability Analysis Of Nonlinear Machining Force Controllers, Robert G. Landers, Yen-Wen Lu

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Model parameters vary significantly during a normal operation, thus, adaptive techniques have predominately been used. However, model-based techniques that carefully account for changes in the force process have again been examined due to the reduced complexity afforded by such techniques. In this paper, the effect of model parameter variations on the closed-loop stability for two model-based force controllers is examined. It was found that the stability boundary in the process parameter space can be exactly determined for force control systems designed for static force processes. For force control systems designed for first-order force processes, it was found that the stability …