Engineering Commons^™

Static And Dynamic Obstacle Avoidance For Miniature Air Vehicles, Jeffery Brian Saunders, Brandon Call, Andrew Curtis, Randal W. Beard, Timothy W. Mclain

Faculty Publications

Small unmanned air vehicles are limited in sensor weight and power such that detection and avoidance of unknown obstacles during flight is difficult. This paper presents a low power low weight method of detection using a laser range finder. In addition, a rapidly-exploring random tree algorithm to generate waypoint paths around obstacles known a priori is presented, and a dynamic geometric algorithm to generate paths around detected obstacles is derived. The algorithms are demonstrated in simulation and in flight tests on a fixed-wing miniature air vehicle (MAV).

Antiplane Surface Acoustic Waves Propagating In Elastic Half-Space Coated With An Anisotropic Laminate, Xiangfa Wu, Yuris A. Dzenis

Department of Engineering Mechanics: Faculty Publications

Dispersion relation of antiplane surface acoustic waves (SAWs) propagating in elastic half-space coated with an anisotropic laminate was determined explicitly by means of Stroh's formalism within the subsonic range, where is no energy leakage into the substrate. During the procedure, the governing dynamic equation in each anisotropic layer and the displacement–traction continuity at interfaces were exactly satisfied by Stroh's functions. Explicit algebraic equation was derived for determining the dispersion relation. As an example, the wave number vs. phase velocity diagram for steel half-space coated with a graphite-fiber/epoxy laminate with a [± 45°/0°₂] lay-up was demonstrated. The given method …

Manufacturing Companies And The Information Age In The U.S., Marcos Reynero

Graduate Research Papers

The purpose of this research paper is to analyze the relationship between the amount of indirect labor and value added in manufacturing companies. Companies are moving manufacturing sites overseas in order to reduce cost. The cost of direct labor in countries like China is relatively lower in comparison to the cost of labor in the U.S. Edward Hill, professor at Cleveland State University's College of Urban Affairs, states that an hour of a manufacturing plant in the U.S. costs $150 versus $1 in China (Scherer, 2005). Companies are making strategic decisions based on reducing cost in order to improve profits. …

Protein Impregnated Polymer (Pip) Film Infrared Sensor Using Suspended Microelectromechanical Systems (Mems) Pixels, Tetsuo Kaieda

Theses and Dissertations

The Air Force Research Laboratory Materials and Manufacturing Directorate have developed a novel protein impregnated polymer (PIP) suspension that changes resistivity as a function of absorbed infrared radiation. Due to this property, the PIP is a potential material for use as an uncooled bolometer, or thermal sensor. In this research, a thermally-isolated pixel design, sensor characterization methods, and sensor fabrication and processing steps were developed. To create a microbolometer, the PIP was applied to two prototype micro-electro-mechanical systems (MEMS) surface micro-machined structures. The first is a raised cantilever pixel array that uses residual stress polysilicon and metal film arms to …

Robust Techniques And Applications In Fuzzy Clustering, Amit Banerjee

Dissertations

This dissertation addresses issues central to frizzy classification. The issue of sensitivity to noise and outliers of least squares minimization based clustering techniques, such as Fuzzy c-Means (FCM) and its variants is addressed. In this work, two novel and robust clustering schemes are presented and analyzed in detail. They approach the problem of robustness from different perspectives. The first scheme scales down the FCM memberships of data points based on the distance of the points from the cluster centers. Scaling done on outliers reduces their membership in true clusters. This scheme, known as the Mega-clustering, defines a conceptual mega-cluster which …

A Gait Generation Mechanism For Leg Rehabilitation Therapy, Yazan Ahmad Manna

Theses

While most take their ability to walk for granted, some are unable to walk secondary to any number of pathologies, such as traumatic brain injury (TBI), spinal cord injury (SCI), cerebrovascular accidents (CVA), cerebral palsy (CP), multiple sclerosis (MS), Parkinson's disease, as well as various orthopedic conditions. Decreased activity has been shown to be associated with rapidly deconditioning and other co-morbidities. Rehabilitation techniques that afford patients the ability to begin reconditioning through walking sooner may ultimately enhance their return to a better quality of life.

The overall goal of this study is to design a gait generation mechanism for rehabilitation …

An Investigation Of Improving Wear Of 390 Die-Cast Aluminum Through Hardcoat Anodizing, Michael J. Whiting

Theses and Dissertations

The objectives of this research were to investigate the wear that occurs on the surface of a Hardcoat anodized die-cast aluminum surface, which was sliding against a composite rubber belt. This research investigated known wear theories and the results for previous testing to understand the mechanisms that were likely occurring in this application. These theories indicated that the wear occurring may be reduced by changing the hardness of the materials involved. Archard's equation gave tangible evidence of this fact, but related to the base material and not a surface coating. It was hypothesized that Hardcoat anodizing would follow the theory …

Approximate Thermal Modeling Of Radiofrequency Cardiac Ablation, Aaron Joseph Walter

Theses and Dissertations

The ultimate objective of the research which led to this thesis is to increase the efficacy and safety of radiofrequency catheter ablation (RFCA) of cardiac tissue. The purpose of RFCA is to carefully heat selected locations in the heart. The resulting thermal injury creates lesions which prevent the generation or propagation of arrhythmias. The ability to predict the appropriate amount of energy required at any ablation site is essential to increasing the efficacy and safety of RFCA. The research documented in this thesis focuses on the development of an approximate thermal model of the time-dependent temperature profile within the myocardium …

Apparatus And Method For Three-Dimensional Contouring, Carl B. Kieranen, Charles A. Hallstrom, Glen R. Simula, Nils P. Ruonavaara, James D. Waineo

Michigan Tech Patents

A device and method for contouring three-dimensionally curved surfaces includes an elongated contouring assembly that is supported at opposite ends by height adjustment mechanisms. The height adjustment mechanisms raise and lower the ends of the contouring assembly independently of each other, thereby allowing the contouring assembly to create a three-dimensionally curved surface as it passes over an area to be contoured. The control of at least one end of the contouring assembly is based on a comparison of its measured position with a profile of the surface to be leveled that is stored in a computer memory. A pivot or …

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.

A Method For Characterizing The Properties Of Industrial Foams, Shaun M. Salisbury

Theses and Dissertations

Assessing the effect of foam layers on transport phenomena is of significant interest in many industries, so a method for predicting foam layer properties has been developed. A model of the propagation of radiation from an amplitude-modulated laser beam through a non-absorbing foam layer has been developed using diffusion theory. Measurements predicted by diffusion theory were compared to results generated using Monte Carlo methods for a variety of foam layer properties in both the time-domain and the frequency-domain. The properties that were varied include the layer thickness, the scattering coefficient, and the asymmetry parameter. Layer thicknesses between 8.5 mm and …

Cooperative Control Of Miniature Air Vehicles, Derek R. Nelson

Theses and Dissertations

Cooperative control for miniature air vehicles (MAVs) is currently a highly researched topic. There are many application for which MAVs are well suited, including fire monitoring, surveillance and reconaissance, and search and rescue missions. All of these applications can be carried out more effictively by a team of MAVs than by a single vehicle. As technologies for microcontrollers and small sensors have improved so have the capabilities of MAVs. This improvement in MAV performance abilities increases the possibility for cooperative missions. The focus of this research was on cooperative timing missions. The issues faced when dealing with multi-MAV flight include …

Showering In The Sun, Florida Solar Energy Center, James Haggard

FSEC Energy Research Center®

For thousands of years, man has used energy from the sun to heat water. Today, the typical way of obtaining hot water for a shower is through a residential or commercial thermal system installed on a building. This type of shower is too big and heavy to use outdoors, although camping facilities and parks may have such systems for their patrons. Original outdoor showers that were developed for use in remote locations were bulky and not particularly portable. Today's solar shower is designed to be practical for camping, recreational and marine use. New products are made of plastic for lighter …

Disasters: Photovoltaics For Special Needs, Florida Solar Energy Center, William Young

FSEC Energy Research Center®

The National Hurricane Center tracks the path of a hurricane to determine where it will make landfall. People in harm's way are informed of its approach and the need to evaluate options to prevent injury and protect lives. One of the many groups of people at high risk is those with special needs. They have health conditions that require special care. Before a disaster, these individuals live in hospitals, care facilities and homes. During and following a disaster, many would be moved, along with their supplies, equipment and a caretaker, to a special needs shelter. Others would stay with relatives …

Renewable Energy And Disaster-Resistant Buildings, Florida Solar Energy Center, William Young

FSEC Energy Research Center®

Hurricanes, floods, tornados and earthquakes create natural disasters that can destroy homes, businesses and the natural environment. Such disasters can happen with little or no warning, leaving hundreds or even thousands of people without medical services, potable water, sanitation, communications and electrical services for up to several weeks. The 2004 hurricane season ravaged the State of Florida, U.S.A., with four major hurricanes within a 6-week timeframe. Over nine million people evacuated their homes and damage to property was extensive.

One proactive strategy to minimize this type of destruction and disruption to lives is the implementation of disaster-resistant buildings that are …

Electrohydrodynamic Instability Of Thin Conductive Liquid Films, Xiangfa Wu, Yuris A. Dzenis

Department of Engineering Mechanics: Faculty Publications

This paper considers the effect of surface charges on the surface instability of thin conductive liquid films. A characteristic relation is obtained for determining the wave number of the fastest growing mode as a function of surface tension, dispersive van der Waals force, and electrostatic tractions exerted by the film surface charges. Two natural length scales of the microsystem are further introduced to account for the coupling effects on the dewetting pattern development. The present results can be used for controlled surface pattern modulation in a spinodal-dewetting scenario via amplification of surface waves of selected modes.

Workpiece Alignment For Hybrid Laser Aided Part Repair Process, Ajay Panackal Padathu, Todd E. Sparks, Frank W. Liou

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Work piece alignment is a key issue for hybrid laser aided part repair,a process utilizing both machining and laser deposition.Proper alignment can greatly improve the accuracy of the repair process.This paper introduces a method for aligning a physical work piece and a CAD model using a Renis aw touch probe and software tools. Also discussed is a model for computing 5-axis CNC positions based on a desired work piece orientation.

Part Repair Using A Hybrid Manufacturing System, Kunnayut Eiamsa-Ard, Hari Janardanan Nair, Lan Ren, Jianzhong Ruan, Todd E. Sparks, Frank W. Liou

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Nowadays, part repair technology is gaining more interest from military and industries due to the benefit of cost reducing as well as time and energy saving. Traditionally, part repair is done in the repair department using welding process. The limitations of the traditional welding process are becoming more and more noticeable when the accuracy and reliability are required. Part repair process has been developed utilizing a hybrid manufacturing system, in which the laser aided deposition and CNC cutting processes are integrated. Part repair software is developed in order to facilitate the users. The system and the software elevate the repair …

Determination Of Dynamic Powder Modeling Parameters Via Optical Methods, Todd E. Sparks, Heng Pan, Frank W. Liou

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Dynamic parameters, such as restitution and friction coefficients are important for powder flow simulations of laser based deposition processes. These parameters are difficult to find, especially for industrial metal powders. This paper introduces an optical method for measuring restitution and friction coefficients. The free falling powder flow was illuminated by a laser sheet. In order to obtain particle velocity, streaks proportional to particle velocities was generated by laser pulse obtained by a chopper. Recorded imaged were analyzed to determine particle velocities both before and after various impact conditions as well as impact parameters.

Sensitivity Analysis Of Process Parameters In Laser Deposition, Zhiqiang Fan, Kaushik Phatak, Frank W. Liou

Mechanical and Aerospace Engineering Faculty Research & Creative Works

In laser cladding with powder injection process, process output parameters, including melt pool temperature and melt pool dimensions, are critical for part quality. This paper uses simulation and experiments to investigate the effect of the process input parameters: laser power, powder mass flow rate, and scanning speed on the output parameters. Numerical simulations and experiments are conducted using a factorial design. The results are statistically analyzed to determine the significant factors and their interactions. The simulation results are compared to experimental results. The quantitative agreement/disagreement is discussed and further research is outlined.

Freeze-Form Extrusion Fabrication Of Ceramics, Tieshu Huang, Michael S. Mason, Greg Hilmas, Ming-Chuan Leu

Materials Science and Engineering Faculty Research & Creative Works

A novel, environmentally friendly solid freeform fabrication method called Freeze-form Extrusion Fabrication (FEF) has been developed for the fabrication of ceramic-based components. The method is based on deposition of ceramic pastes using water as the media. The ceramic solids loading can be 50 vol. % or higher and initial studies have focused on the use of aluminum oxide (Al₂O₃). The FEF system components and their interaction are examined, and the main process parameters affecting part geometry defined. 3-D shaped components have been fabricated by extrusion deposition of the ceramic paste in a layer-by-layer fashion. The feasibility …

Experimental Investigation Of The Travel-Time Variance Of An Acoustic Wave Propagating Through The Grid-Generated Turbulence, Tatiana A. Andreeva, William W. Durgin

Office of the Provost Scholarship

An experimental technique for the investigation of the behaviour of acoustic wave propagation through a turbulent medium is discussed. The present study utilizes the ultrasonic travel-time technique to diagnose a grid-generated turbulence. Travel-time variance is studied versus mean flow velocity, travel distance and outer turbulence scale. The effect of thermal fluctuations, which result in fluctuations of sound speed, is studied using a heated-grid experiment. Experimental data obtained using ultrasonic technique confirm numerical and theoretical predictions of nonlinear increase of the travel-time variance with propagation distance, which could be connected to the occurrence of caustics. The effect of turbulent intensity on …

Robust Initial Matching Of Free-Form Objects Represented By Point Cloud Data, Nimun A. Jahangir

Digitized Theses

No abstract provided.

Evolutionary Algorithm For The Placement Of Fluid Power Valves On A Valve Stand, Trichy M. Kethara Pasupathy, Ravi Teja Seethamraju, Robert G. Wilhelm

Department of Mechanical and Materials Engineering: Faculty Publications

The choice of placement of fluid power valves on a valve stand and routing by pipes has an impact on operational costs. Choosing the right placement that provides optimum routing configuration or determining the optimum routing for a chosen placement are both computationally hard problems. An evolutionary algorithm (EA), to minimize operational costs while optimizing placement and routing of valves, is developed here. The best practices in the industry are abstracted and implemented in the EA. In this paper, the algorithm and its performance for examples with varying complexities are presented. Our results meet or exceed experienced designers’ solutions.

Experimental Determination Of Probabilistic Edge-Delamination Strength Of A Graphite–Fiber/Epoxy Composite, Xiangfa Wu, Yuris A. Dzenis

Department of Engineering Mechanics: Faculty Publications

Probabilistic edge-delamination strength of a thermosetting polymer composite was studied experimentally in this work. During the procedure, by means of edge-delamination tensile test, the graphite–fiber/epoxy laminate made of unidirectional Toray P7051S- 20Q-1000 prepregs with an optimized lay-up of [12₂/–12₂/0₂]_S was used for examining its probabilistic distributions of the edgedelamination onset stress and the ultimate tensile strength. Acoustic emission (AE) equipment and optical microscope were utilized to capture the edge-delamination initiation and characterize the failure modes during delaminating. Fractographical analysis based on scanning electron microscope (SEM) was conducted for the characterization of the microscopic …

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 …

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 …

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 …

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 …

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 …