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Articles 9391 - 9420 of 11119

Full-Text Articles in Engineering

Operator State Estimation For Adaptive Aiding In Uninhabited Combat Air Vehicles, Christopher A. Russell Sep 2005

Operator State Estimation For Adaptive Aiding In Uninhabited Combat Air Vehicles, Christopher A. Russell

Theses and Dissertations

This research demonstrated the first closed-loop implementation of adaptive automation using operator functional state in an operationally relevant environment. In the Uninhabited Combat Air Vehicle (UCAV) environment, operators can become cognitively overloaded and their performance may decrease during mission critical events. This research demonstrates an unprecedented closed-loop system, one that adaptively aids UCAV operators based on their cognitive functional state A series of experiments were conducted to 1) determine the best classifiers for estimating operator functional state, 2) determine if physiological measures can be used to develop multiple cognitive models based on information processing demands and task type, 3) determine …

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Privatization Of Space Ventures: Proposing A Proven Regulatory Theory For Future Extraterrestral Appropriation, Jonathan Thomas Aug 2005

Privatization Of Space Ventures: Proposing A Proven Regulatory Theory For Future Extraterrestral Appropriation, Jonathan Thomas

Brigham Young University International Law & Management Review

No abstract provided.

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Adaptive Control Of A Projectile Fin Using Piezoelectric Elastic Beam, Smitha Mani, Sahjendra N. Singh, Surya Kiran Parimi, Woosoon Yim, Mohamed B. Trabia Aug 2005

Adaptive Control Of A Projectile Fin Using Piezoelectric Elastic Beam, Smitha Mani, Sahjendra N. Singh, Surya Kiran Parimi, Woosoon Yim, Mohamed B. Trabia

Mechanical Engineering Faculty Research

No abstract provided.

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Variable Structure Control Of Unsteady Nonlinear Aeroelastic System, With Partial State Information, Sushma Gujjula, Sahjendra N. Singh Aug 2005

Variable Structure Control Of Unsteady Nonlinear Aeroelastic System, With Partial State Information, Sushma Gujjula, Sahjendra N. Singh

Electrical & Computer Engineering Faculty Research

This paper treats the question of control of a two-degree-of-freedom unsteady aeroelastic system with partial state information in the presence of uncertainties. The chosen model describes the plunge and pitch motion of a wing and a single trailing-edge control surface is utilized for the purpose of control. Based on the Lyapunov approach, a variable structure control law is derived. For the control law derivation, the system is treated as the interconnection of two subsystems in which the subsystem associated with the unsteady aerodynamics is input-to-state stable. The stability property of this subsystem is exploited to generate a dominating signal for …

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An Experimental Investigation Of Ionization Of Supersonic Air By A Corona Discharge, Udyavar S. Satyanand Aug 2005

An Experimental Investigation Of Ionization Of Supersonic Air By A Corona Discharge, Udyavar S. Satyanand

Mechanical and Aerospace Engineering Dissertations - Archive

A technique is developed to ionize supersonic air flow in a shock tube by a weak corona discharge. The driven section of the tube is open to the atmosphere. The shock propagates in the driven section at about 1 km/s by means of an area contraction near the downstream end of the driven section. Air is ionized by a unipolar corona discharge device comprising of a sharp-edged wedge as a high-field electrode inserted in a 41.25 mm (2 in.) ID tube that forms a low-field electrode. The device requires less than 0.5 W. A ring probe, downstream of the corona …

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Numerical Simulation Of Pulse Detonation Phenomena In A Parallel Environment, Prashaanth Ravindran Aug 2005

Numerical Simulation Of Pulse Detonation Phenomena In A Parallel Environment, Prashaanth Ravindran

Mechanical and Aerospace Engineering Theses - Archive

The objective of this work was to develop a parallel algorithm that would be used in the simulation of the detonation process in the chamber of a pulse detonation engine. The emphasis is laid on reducing computation time while maintaining the accuracy of the solution and subsequently developing a numerical solution to be in agreement with real-world physical characteristics of a detonation wave initiation, build-up and progression. The flow is assumed to be unsteady, inviscid and non heat conducting. To adhere to real time effects, the flow equations are coupled with finite rate chemistry and the vibrational energy equation are …

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An Approximate Solution To Buckling Of Plates By The Galerkin Method, Yattender Rishi Dubey Aug 2005

An Approximate Solution To Buckling Of Plates By The Galerkin Method, Yattender Rishi Dubey

Mechanical and Aerospace Engineering Theses - Archive

This thesis presents a semi-analytical method to solve the governing differential equation of plates using the Galerkin method. Symbolic algebra software is extensively used to perform necessary calculations. In this thesis, the lateral deflection of a plate is expressed in a series of polynomials each of which satisfies the given homogeneous boundary conditions. The coefficients of these polynomials are found out by the Galerkin method. Symbolic algebra software works best while handling necessary algebra to generate admissible polynomials and build required matrices for solving for the coefficients.This thesis demonstrates the calculation of the lateral load for different plates under different …

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Spreading, Solidification And Remelting Behavior Of Liquid Metal Droplets Sequentially Impinging Onto A Metal Substrate, Lister Manohar Pinto Aug 2005

Spreading, Solidification And Remelting Behavior Of Liquid Metal Droplets Sequentially Impinging Onto A Metal Substrate, Lister Manohar Pinto

Mechanical and Aerospace Engineering Theses - Archive

The fluid dynamics and simultaneous solidification of two successive molten metal droplets impacting a flat substrate is investigated numerically. The primary objective is to investigate the effects of initial droplet and substrate temperature, and the latent heat of substrate material, on the spreading, solidification and remelting of molten tin droplets impacting a substrate of the same material. A robust fluid-flow solver that is capable of modeling rapidly deforming free surfaces involving a moving phase-change boundary is employed in the study. The Navier-Stokes equations are solved using a finite volume formulation. A two-step projection method is used to solve for incompressible …

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Design Optimization And Synthesis Of Manipulators Based On Various Manipulation Indices, Sandipak Bagchi Aug 2005

Design Optimization And Synthesis Of Manipulators Based On Various Manipulation Indices, Sandipak Bagchi

Mechanical and Aerospace Engineering Theses - Archive

Design optimization of serial manipulators involves striking a balance between an appropriate joint angle and exact link lengths. The optimization technique used in this thesis uses a unique algorithm that optimizes the joint angle through an Inverse Kinematics program. The synthesis problem involves setting up an accurate design length so as to reach a set of given target points inside the workspace without any singularity. The optimization process based on task specification focuses on the maximization of manipulability index, the objective function subjected to link length and joint angle constraints. The results obtained were plotted and animated to visualize the …

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Polymer Tube Embedded In-Plane Micropump: Design, Analysis And Fabrication, Ashutosh Kole Aug 2005

Polymer Tube Embedded In-Plane Micropump: Design, Analysis And Fabrication, Ashutosh Kole

Mechanical and Aerospace Engineering Theses - Archive

This thesis presents the design, analysis, and fabrication of a novel polymer tube embedded in-plane micropump. The key component of the proposed micropump is a Parylene polymer tube that is embedded into the trench of a silicon die. Advantages of embedding a Parylene polymer tube are biocompatibility and leakage free environments. The issue of leakage of fluid presented in [1] is eliminated by inserting the polymer tube. The tube itself acts as a diaphragm, which transfers the force and motion of thermal actuators to fluid. The structural analysis and the fabrication of the Parylene tube along with the coupled-field multiphysics …

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The University Cubesat Initiative: It's Global Acceptance, Some Present Projects And Speculation As To It's Future, Robert J. Twiggs Jul 2005

The University Cubesat Initiative: It's Global Acceptance, Some Present Projects And Speculation As To It's Future, Robert J. Twiggs

Robert "Bob" Twiggs STEM Education Collection

A PowerPoint Presentation created by Professor Bob Twiggs titled "The University CubeSat Initiative: It's Global Acceptance, Some Present Projects and Speculation as to It's Future" from July 27, 2005.

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Study Of Blast Wave Impact On Concrete, Ajit Geevarghese John Jul 2005

Study Of Blast Wave Impact On Concrete, Ajit Geevarghese John

Mechanical and Aerospace Engineering Theses - Archive

The past decade has brought an upsurge of terrorist attacks throughout the world. A common form of attack is bombings employed against a civilian structure. These bombs lead to blast waves resulting from high explosive bursts in air, causing severe structural damage to buildings that often collapse before evacuation is possible. These blast waves subject the buildings to repeated dynamic loading in the form of reflecting shock waves which then finally lead to their destruction. Many studies have been carried out to understand the static loading of these structures. The current study is to protect existing buildings from an explosion. …

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Research For Dynamic Seal Friction Modeling In Linear Motion Hydraulic Piston Applications, Brian Edward Suisse Jul 2005

Research For Dynamic Seal Friction Modeling In Linear Motion Hydraulic Piston Applications, Brian Edward Suisse

Mechanical and Aerospace Engineering Theses - Archive

This paper presents a unique physics-based analytic model for dynamic seal friction in hydraulic actuators as a function of cylinder pressure, seal material, piston rod dimensions, piston rod seal gland dimensions, and other influencing factors. Results from a series of friction tests are presented. Finite element analysis of an installed seal is used to predict contact stress between the seal and the gland, providing a normal force against the sealing surface. This information is used to determine coefficients of friction within the test specimen. From the analysis, a pressure-sensitive model is generated. The friction model is overlaid on the test …

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Maneuvering Control Of A Spacecraft With Propellant Sloshing, Philip A. Savella Jul 2005

Maneuvering Control Of A Spacecraft With Propellant Sloshing, Philip A. Savella

Master's Theses - Daytona Beach

Propellant slosh has been a problem studied in spacecraft designs since the early days of large, liquid-fuel rockets. The conventional design solution involves physical structures inside the fuel tanks that limit propellant motion. Although effective, baffles and bladders add to spacecraft mass and structural complexity. In this research, the sloshing fuel mass is treated as an unactuated degree of freedom within a rigid body. Specifically, the propellant is modeled as a pendulum mass anchored at the center of a spherical tank. After obtaining the coupled equations of motion, several linear controllers are developed to achieve planar spacecraft pitch-maneuvers while suppressing …

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Investigation Of Minimum Response For Damage Assessment, Jeffrey Kirk Jul 2005

Investigation Of Minimum Response For Damage Assessment, Jeffrey Kirk

Mechanical and Aerospace Engineering Theses - Archive

Assessment of structural damage based on changes in vibratory response characteristics has been researched for many years, with much attention directed toward the use of modal parameters. Modal responses contribute to form points of local minima in the frequency response of a system. The frequency and amplitude values corresponding to these points of minimum response can be analytically determined, experimentally measured, and shown to exhibit sensitivity to damage. This work was performed to investigate the possible contribution that explicitly targeted minimum response information could provide in a damage detection process. A simple 6-DOF discrete spring-mass system was used to conduct …

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Computational Sensing And Closed-Loop Active Flow Control Of Airfoil At Post-Stall Conditions, Volkan Kamaci Jul 2005

Computational Sensing And Closed-Loop Active Flow Control Of Airfoil At Post-Stall Conditions, Volkan Kamaci

Mechanical & Aerospace Engineering Theses & Dissertations

Flow separation over lifting aerodynamic components, such as airfoils and wings, occurs during stall conditions which are caused by adverse changes (i.e. high angle of attack, inflow conditions, etc.) in the operating conditions of aerodynamic components. During stall conditions, the flow over airfoil loses its momentum, creating high pressure zones on the upper surface of the airfoil and even a small increase in pressure causes the fluid particles to stop and separate to a low pressure zone. In order to eliminate the flow separation, the low momentum flow should be removed in order to maintain the high momentum and low …

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Electromagnetic Wave Propagation Prediction For Wireless Networks Inside Boeing Fuselages, Mennatoallah Youssef Jul 2005

Electromagnetic Wave Propagation Prediction For Wireless Networks Inside Boeing Fuselages, Mennatoallah Youssef

Electrical & Computer Engineering Theses & Dissertations

Commercial grade software is intended for electromagnetic predictions within office buildings; it was used to develop models to analyze propagation inside airplane fuselages. This study shows that Wireless XGTD and Insite software can accurately predict power propagation within airplane fuselages. Current work uses fuselage models, which contain additional internal components. A comparison was made between empty and full fuselage to examine the effects of internal components. Two propagation model types [Fast 3D and Full 3D] were also compared for accuracy to experimental study. It was concluded that completed fuselages are suggested for further simulation study as well as that the …

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Electromagnetic Propagation Prediction Inside Aircraft Cabins, Genevieve Hankins Jul 2005

Electromagnetic Propagation Prediction Inside Aircraft Cabins, Genevieve Hankins

Electrical & Computer Engineering Theses & Dissertations

Electromagnetic propagation models for signal strength prediction within aircraft cabins are essential for evaluating and designing a wireless communication system to be implemented onboard aircraft. There are many commercially available software packages for predicting wireless system performance in conventional indoor environments. It is of interest to examine the available software to determine if the aircraft's electromagnetic environment (EME) can be modeled successfully without developing an aircraft specific prediction tool. EnterprisePlanner®, a registered product of Wireless Valley Communications, Incorporated, was selected for the present effort. The performance of the prediction model was evaluated through a comparison with field measurements taken on …

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Active Control Of Large Amplitude Nonlinear Free Vibrations And Nonlinear Supersonic Panel Flutter Of Beams And Composite Plates Using Piezoelectric Self-Sensing Actuators, Qinqin Li Jul 2005

Active Control Of Large Amplitude Nonlinear Free Vibrations And Nonlinear Supersonic Panel Flutter Of Beams And Composite Plates Using Piezoelectric Self-Sensing Actuators, Qinqin Li

Mechanical & Aerospace Engineering Theses & Dissertations

This thesis employs a coupled structural-electrical finite element modal formulation for the control of nonlinear free vibrations, and supersonic panel flutter of beams and composite plates with and without thermal environment. Multiple modes of the nonlinear free vibration and supersonic panel flutter are considered in the closed loop simulations. Two different controllers are designed and investigated. The first one is the output feedback controller comprised of a Linear Quadratic Regulator (LQR) and an Extended Kalman Filter (EKF). EKF considers the nonlinear state space matrix and has a gain sequence evaluated on-line. Thus the LQR/EKF nonlinear controller has more accurate state …

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Introduction To Product Design And Innovation: A Cross Disciplinary Mini Curriculum, Patricia Backer, Seth Bates Jun 2005

Introduction To Product Design And Innovation: A Cross Disciplinary Mini Curriculum, Patricia Backer, Seth Bates

Faculty Publications

For the past two years, faculty at San Jose State University (SJSU) have implemented a three- semester minicurriculum in Product Design and Manufacturing. The project follows the Project- Based Learning (PBL) model and is central to the Certificate Program in Product Design in the Mechanical Engineering Department, the Manufacturing Systems concentration in the Department of Aviation and Technology, and the Industrial Design Program in the School of Art and Design. Students in the three courses in the minicurriculum face design challenges while being instructed about the constraints of manufacturability. In each course, students develop three to four products. All products …

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A Flash Vaporization System For Detonation Of Hydrocarbon Fuels In A Pulse Detonation Engine, Kelly C. Tucker Jun 2005

A Flash Vaporization System For Detonation Of Hydrocarbon Fuels In A Pulse Detonation Engine, Kelly C. Tucker

Theses and Dissertations

Current research by the US Air Force and Navy is concentrating on obtaining detonations in a pulse detonation engine (PDE) with low vapor pressure, kerosene based jet fuels. These fuels have a low vapor pressure and the performance of a liquid hydrocarbon fueled PDE is significantly hindered by the presence of fuel droplets. A high pressure, fuel flash vaporization system (FVS) has been designed and built to reduce and eliminate the time required to evaporate the fuel droplets. Four fuels are tested: n-heptane, isooctane, aviation gasoline, and JP-8. The fuels vary in volatility and octane number and present a clear …

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Technology And You: Working With The Aerospace Industry To Enhance Engineering Education, Russell M. Cummings, John H. Mcmasters Jun 2005

Technology And You: Working With The Aerospace Industry To Enhance Engineering Education, Russell M. Cummings, John H. Mcmasters

Aerospace Engineering

While many engineers in the aerospace engineering profession know that interacting with students is a good idea, few of them know how to do it. Certainly some engineers are asked on occasion to give lectures at various university club meetings, and some are even heavily involved in interacting with students working on various design projects, but the average engineer has little or no interaction with students over the course of their career. A number of companies, including Boeing, have created technical interest groups to encourage mentoring and sharing of corporate knowledge throughout the company. These efforts have been met with …

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Special Issue: Engineering Applications Of Representations Of Function, Part 2, Robert B. Stone, Amaresh Chakrabarti Jun 2005

Special Issue: Engineering Applications Of Representations Of Function, Part 2, Robert B. Stone, Amaresh Chakrabarti

Mechanical and Aerospace Engineering Faculty Research & Creative Works

No abstract provided.

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Three-Dimensional Radiative Transfer In An Isotropically Scattering, Plane-Parallel Medium: Generalized X- And Y-Functions, D. W. Mueller, A. L. Crosbie Jun 2005

Three-Dimensional Radiative Transfer In An Isotropically Scattering, Plane-Parallel Medium: Generalized X- And Y-Functions, D. W. Mueller, A. L. Crosbie

Mechanical and Aerospace Engineering Faculty Research & Creative Works

The topic of this work is the generalized X- and Y-functions of multidimensional radiative transfer. the physical problem considered is spatially varying, collimated radiation incident on the upper boundary of an isotropically scattering, plane-parallel medium. an integral transform is used to reduce the three-dimensional transport equation to a one-dimensional form, and a modified Ambarzumian's method is used to derive coupled, integro-differential equations for the source functions at the boundaries of the medium. the resulting equations are said to be in double-integral form because the integration is over both angular variables. Numerical results are presented to illustrate the computational characteristics of …

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Experimental Investigation Into The Aerodynamic Ground Effect Of A Tailless Chevron-Shaped Ucav, Brett L. Jones Jun 2005

Experimental Investigation Into The Aerodynamic Ground Effect Of A Tailless Chevron-Shaped Ucav, Brett L. Jones

Theses and Dissertations

This experimental study adequately identified the ground effect region of an unmanned combat air vehicle (UCAV). The AFIT 3' x 3' low-speed wind tunnel and a ground plane were used to simulate the forces and moments on a UCAV model in ground effect. The chevron planform used in this study was originally tested for stability and control and the following extends the already existing database to include ground effects. The ground plane was a flat plate mounted with cylindrical legs. To expand the capabilities of the AFIT 3' x 3' low-speed wind tunnel, hot-wire measurements and flow visualization revealed an …

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Parametric Study Of The Towline Shape Of An Aircraft Decoy, Tyler L. Richardson Jun 2005

Parametric Study Of The Towline Shape Of An Aircraft Decoy, Tyler L. Richardson

Theses and Dissertations

Some of today's aircraft use decoys as a defense against enemy weapons. The decoy is towed behind the aircraft with the intention of attracting the weapon propagator by deception, trying to mislead the weapon into detecting it instead of the aircraft. An aircraft deploys a decoy via a towline extending out behind and below the aircraft. However, during some maneuvers, the towline moves up into the jet exhaust plume of the aircraft. The high temperatures of the exhaust can cause damage to the towline cable, ranging from disrupting data flow between the decoy and aircraft to severing the towline altogether. …

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Design And Ground-Testing Of An Inflatable-Rigidizable Structure Experiment In Preparation For Space Flight, Chad R. Moeller Jun 2005

Design And Ground-Testing Of An Inflatable-Rigidizable Structure Experiment In Preparation For Space Flight, Chad R. Moeller

Theses and Dissertations

As the demand for larger space structures increases, complications arise including physical dimensions, weight, and launch costs. These constraints have forced the space industry to look for smaller, more lightweight, and cost-effective solutions. Future antennas, solar sails, sun shields, and other structures have the potential to be exponentially larger than their launch envelopes. Current research in this area is focused on the use of inflatable, rigidizable structures to reduce payload size and mass, ultimately reducing launch costs. These structures can be used as booms, trusses, wings, or can be configured to almost any simple shape. More complex shapes can be …

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Hierarchical Optimal Force-Position-Contour Control Of Machining Processes. Part Ii. Illustrative Example, Yan Tang, Robert G. Landers, S. N. Balakrishnan Jun 2005

Hierarchical Optimal Force-Position-Contour Control Of Machining Processes. Part Ii. Illustrative Example, Yan Tang, Robert G. Landers, S. N. Balakrishnan

Mechanical and Aerospace Engineering Faculty Research & Creative Works

There has been a tremendous amount of research in machine tool servomechanism control, contour control, and machining force control; however, to date these technologies have not been tightly integrated. This paper develops a hierarchical optimal control methodology for the simultaneous regulation of servomechanism positions, contour error, and machining forces. The contour error and machining force process reside in the top level of the hierarchy where the goals are to 1) drive the contour error to zero to maximize quality and 2) maintain a constant cutting force to maximize productivity. These goals are systematically propagated to the bottom level, via aggregation …

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Hierarchical Optimal Force-Position-Contour Control Of Machining Processes. Part I. Controller Methodology, Yan Tang, Robert G. Landers, S. N. Balakrishnan Jun 2005

Hierarchical Optimal Force-Position-Contour Control Of Machining Processes. Part I. Controller Methodology, Yan Tang, Robert G. Landers, S. N. Balakrishnan

Mechanical and Aerospace Engineering Faculty Research & Creative Works

There has been a tremendous amount of research in machine tool servomechanism control, contour control, and machining force control; however, to date these technologies have not been tightly integrated. This paper develops a hierarchical optimal control methodology for the simultaneous regulation of servomechanism positions, contour error, and machining forces. The contour error and machining force process reside in the top level of the hierarchy where the goals are to 1) drive the contour error to zero to maximize quality and 2) maintain a constant cutting force to maximize productivity. These goals are systematically propagated to the bottom level, via aggregation …

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Drag Estimates For The Joined-Wing Sensor Craft, Ryan L. Craft Jun 2005

Drag Estimates For The Joined-Wing Sensor Craft, Ryan L. Craft

Theses and Dissertations

This research studied the drag effects of the joined-wing sensor craft technology demonstrator being developed at the Air Force Research Laboratory (AFRL). Although many performance parameters have been studied and evaluated for this vehicle, to date no detailed drag estimates have been conducted for the AFRL configuration. Previous performance parameters of the aircraft have been estimated based solely on a constant lift-to-drag ratio assumption. Using the Air Vehicles Technology Integration Environment created by Dr. Maxwell Blair, and supplemented by MATLAB code, this study explored three different drag prediction methods to determine accurate estimates of both parasite and induced drag. The …

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