Engineering Commons^™

Development And Analysis Of A Software Package To Quantify In Vivo Polyethylene Wear After Total Hip Arthroplasty, Allison Kinney, Catherine G. Ambrose

Mechanical and Aerospace Engineering Faculty Publications

Since the first total hip arthroplasty (THA) in 1938, THA evolved and developed into one of the major concentrations of orthopaedic research. The typical hip implant device used today incorporates a femoral and an acetabular component that serve to replicate the anatomical and mechanical functions of the natural hip joint. However, several problems exist that can effect the function of the implant device. Wear in the polyethylene liner of the acetabular component of the total hip replacement device is known as one of the major factors that affects the longevity of total hip replacement devices. Both manual and computer-aided techniques …

Cooperative Uav Formation Flying With Obstacle/Collision Avoidance, Xiaohua Wang, Vivek Yadav, S. N. Balakrishnan

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Navigation problems of unmanned air vehicles (UAVs) flying in a formation in a free and an obstacle-laden environment are investigated in this brief. when static obstacles popup during the flight, the UAVs are required to steer around them and also avoid collisions between each other. In order to achieve these goals, a new dual-mode control strategy is proposed: a “safe mode” is defined as an operation in an obstacle-free environment and a “danger mode” is activated when there is a chance of collision or when there are obstacles in the path. Safe mode achieves global optimization because the dynamics of …

Shaken Baby Syndrome: Retinal Hemorrhaging. A Biomechanical Approach To Understanding The Mechanism Of Causation, Steven Alex Hans

Mechanical & Aerospace Engineering Theses & Dissertations

Shaken Baby Syndrome (SBS) is a form of abuse where typically an infant, age six months or less, is held and shaken. There may or may not be direct impact associated with this action. Further, there is very little agreement on the actual mechanism of SBS. Clinical studies are limited in showing the exact mechanism of injury and only offer postulations and qualitative descriptions. SBS has received much attention in the media, has resulted in a great deal of litigation and can be the source of unfounded accusations. Therefore, it is necessary to try to quantify the forces that may …

Reinforcement Learning Based Output-Feedback Control Of Nonlinear Nonstrict Feedback Discrete-Time Systems With Application To Engines, Peter Shih, Jonathan B. Vance, Brian C. Kaul, Jagannathan Sarangapani, J. A. Drallmeier

Electrical and Computer Engineering Faculty Research & Creative Works

A novel reinforcement-learning based output-adaptive neural network (NN) controller, also referred as the adaptive-critic NN controller, is developed to track a desired trajectory for a class of complex nonlinear discrete-time systems in the presence of bounded and unknown disturbances. The controller includes an observer for estimating states and the outputs, critic, and two action NNs for generating virtual, and actual control inputs. The critic approximates certain strategic utility function and the action NNs are used to minimize both the strategic utility function and their outputs. All NN weights adapt online towards minimization of a performance index, utilizing gradient-descent based rule. …

Software Engineering: A Fundamental Approach To Automate And Interface Medical Electronic Systems With Computers In Healthcare Systems, Hashim Twaakyondo

Tanzania Journal of Engineering and Technology (TJET)

The cost for application software and propriatry standards (i.e. data structure and formats) required for storing clinical datasets from electronic device cause the use of time-consuming paper-based documentation and/or the transfer of electronic lab records manually to the PC database systems in Mother-Offspring Malaria Study (MOMS) Laboratory Unit located in Morogoro Regional Hospital, Tanzania. We have explored the ability to extract laboratory results from Haematology analyzer machine for easy management, access and storage. The methodology and tools used during the study includes; site survey and hands-on practice for requirement engineering, visual basic 6.0 for interface design and Microsoft Access for …

Adhesive Contact In Filaments, Xiang-Fa Wu, Yuris A. Dzenis

Department of Engineering Mechanics: Faculty Publications

This paper studies the elastic contact in filaments induced by surface adhesion, which plays an important role in the mechanical response of fibrous materials (e.g., fiber friction, sliding, compression hysteresis, etc.). During the process, a simple 3D elastic contact model was proposed. The filaments were assumed to be uniform, smooth elastic cylinders, and the adhesive force between filaments in contact was estimated according to Bradley’s approach (Bradley 1932 Phil. Mag. 13 853) that relies on the filament configurations before deformation. Under the action of fiber surface adhesion, the elastic deformation and the size of the contact zone were determined in …

Radio Frequency Mems Switch Contact Metal Selection, Ronald A. Coutu Jr., Paul E. Kladitis, Robert L. Crane, Kevin D. Leedy

AFIT Patents

A method for selecting metal alloys as the electric contact materials for microelectromechanical systems (MEMS) metal contact switches. This method includes a review of alloy experience, consideration of equilibrium binary alloy phase diagrams, obtaining thin film material properties and, based on a suitable model, predicting contact electrical resistance performance. After determination of a candidate alloy material, MEMS switches are conceptualized, fabricated and tested to validate the alloy selection methodology. Minimum average contact resistance values of 1.17 and 1.87 ohms are achieved for micro-switches with gold (Au) and gold-platinum (Au-(6.3 at %)Pt) alloy contacts. In addition, `hot-switched` life cycle test results …

Fabrication Of Net-Shape Functionally Graded Composites By Electrophoretic Deposition And Sintering: Modeling And Experimentation, E.A. Olevsky, X. Wang, A. Maximenko, M.A. Meyers

Industrial and Manufacturing Engineering

It is shown that electrophoretic deposition (EPD) sintering is a technological sequence that is capable of producing net-shape bulk functionally graded materials (FGM). By controlling the shape of the deposition electrode, components of complex shapes can be obtained. To enable sintering net-shape capabilities, a novel optimization algorithm and procedure for the fabrication of net-shape functionally graded composites by EPD and sintering has been developed. The initial shape of the green specimen produced by EPD is designed in such a way that the required final shape is achieved after sintering-imposed distortions. The optimization is based on a special innovative iteration procedure …

Vector Field Path Following For Miniature Air Vehicles, Timothy Mclain, Derek R. Nelson, D. Blake Barber, Randall W. Beard

Faculty Publications

In this paper, a method for accurate path following for miniature air vehicles is developed. The method is based on the notion of vector fields, which are used to generate desired course inputs to inner-loop attitude control laws. Vector-field path-following control laws are developed for straight-line paths and circular arcs and orbits. Lyapunov stability arguments are used to demonstrate asymptotic decay of path-following errors in the presence of constant wind disturbances. Experimental flight tests have demonstrated mean path-following errors on less than one wingspan for straight-line and orbit paths and less than three wingspans for paths with frequent changes in …

The Current Generation Of Integrated Engineering Curriculum, Michael A. Collura, Samuel Bogan Daniels, Jean Nocito-Gobel, David Harding

Engineering and Applied Science Education Faculty Publications

In September of 2004 our university adopted the Multidisciplinary Engineering Foundation Spiral Curriculum as the basis for disciplinary engineering programs in Chemical, Civil, Electrical, Mechanical and General Engineering. The curriculum includes a sequence of first and second year engineering courses, matched closely with the development of students’ mathematical sophistication and analytical capabilities and integrated with course work in the sciences. Students develop a conceptual understanding of engineering basics in this series of courses which stress practical applications of these principles. The new curriculum was designed to provide students with a multidisciplinary perspective while developing basic engineering skills and fostering an …

Developing A Matlab/Simulink Rtwt Based Hydraulic Servo Control Design Experiment, Charles Birdsong

Mechanical Engineering

While one of the stated goals of the Mechanical Engineering Controls course is to develop the tools to design a controller, previous lab experiences did not include an experimental exercise in controller design. This was primarily due to the difficulty in implementing a controller that is robust and flexible enough to accommodate different student designs within the short time constraints of a three hour lab period. This paper describes an effort to use the Mathworks Real Time Windows Target to implement student controller designs on real hardware in a lab setting. Students use experimental data and a physically based model …

Civil And Mechanical Engineering Students Learning Mechanics In A Multidisciplinary Engineering Foundation Spiral, Jean Nocito-Gobel, Gregory Broderick, Samuel Bogan Daniels, Michael Collura, Richard Stanley

Engineering and Applied Science Education Faculty Publications

This paper describes how mechanical and civil engineering students are introduced to and develop an understanding of mechanics concepts through a sequence of integrated courses as part of a new curriculum taken during the freshman and sophomore years. The Multi- Disciplinary Engineering Foundation Spiral is a four-semester sequence of engineering courses, matched closely with the development of students’ mathematical sophistication and analytical capabilities and integrated with course work in the sciences. Students develop a conceptual understanding of engineering basics in this series of courses, which stress practical applications of these principles. Mechanics concepts are introduced in a pair of first …

Application Of Transformative Learning Theory In Engineering Education, John Chen

Mechanical Engineering

The goal of this work-in-progress is to improve student engagement and learning in courses that form the core of a discipline. Such gateway courses represent critical milestones in a student's academic career and have a strong influence on his or her attitude and future success in engineering. We contend that students who struggle in gateway courses do so because they are having difficulty with conceptual transformation, and this project aims to facilitate this change through the ideas advocated within Transformative Learning Theory. The essential elements of this project include the integration of information technologies, provision of rapid feedback to students …

Modeling And Control Of A New 1/4t Servo-Hydraulic Vehicle Active Suspension System, Jyh-Chyang Renn, Tsung-Han Wu

Journal of Marine Science and Technology–Taiwan

Nowadays, the active suspension is the key technology for vehicles to achieve both ride comfort and control performance. In this paper, a new 1/4T servo-hydraulic vehicle active suspension system is developed and two control schemes are utilized. The first one is a conventional PID controller obtained from Ziegler-Nichols method and the second one is the neural network controller. Though these two controllers are quite simple and not new, it is still worth mentioning that this paper emphasizes on the engineering aspects including the design of a servo-hydraulic test rig, the implementation technology of the controllers and the subsequent experimental study. …

Study On The Characteristics Of Tiller Blade Shapes By Spray-Welding Hardening, Jain-Song Ju

Journal of Marine Science and Technology–Taiwan

This study attempts to validate and analyze the mathematical models of the plowing dynamics and trajectory curve for tiller and cultivation blades of a rotary cultivator. Both blades are extensively used in Taiwan. The blade must be protected from intertwisting to ensure high efficiency and uniform resistance of the plow to soil. Theoretical and calculated cutting angles are found to be 85.88° and 84.28°, respectively, while the theoretical and calculated edge-curve angles are 59.70° and 58.31°. The present data confirmed that the tiller blades developed by local companies are suitable for the plowing environment in Taiwan. In order to reduce …

Piv Measurements Of Exit Flow Field Of Centrifugal Fans With Conditional Sampling, Shun-Chang Yen, Jung-Hsuan Liu

Journal of Marine Science and Technology–Taiwan

In this research, we have experimented with two centrifugal fans with the same geometrical configuration. These two fans are designed to rotate at different speeds driven with the same voltage. The Particle Image Velocimetry (PIV) method is applied to measure the instantaneous flow fields at the near-exit region. The AMCA 210 wind tunnel is used to find the efficiency and the performance coefficients. The velocity vectors, streamlines, vorticity contours, velocity distributions, flow rate, and performances are also presented and discussed. We find that higher rotation speed yields better efficiency.

An Investigation Of A Positive Engagement, Continuously Variable Transmission, Brian S. Andersen

Theses and Dissertations

A continuously variable transmission (CVT) is a type of transmission that allows an infinitely variable ratio change within a finite range, allowing the engine to continuously operate in an efficient or high performance range. A brief history of CVTs is presented, including the families under which they can be categorized. A new family of CVTs, with the classification of positive engagement, is presented. Three different published embodiments of CVTs of the positive engagement type are presented describing a meshing problem that exists apparently regardless of the embodiment in this family. The problem is called the non-integer tooth problem and its …

Collapse Analysis Of Nanofibers, Xiang-Fa Wu, Yuris A. Dzenis

Department of Engineering Mechanics: Faculty Publications

Continuous nanofibers fabricated by the electrospinning technique have found increasing applications (e.g., nanofiber composites, nanofiber devices, bioengineering tissue scaffolding, etc.). For a nanofiber network subjected to a small external perturbation, the fiber segments within the network may deflect and stick to each other under the condition that their surface adhesion energy overcomes the elastic strain energy induced by fiber bending. Therefore, this paper aims to study adhesion-induced nanofiber collapse and relevant criteria. A simple fiber collapse model was proposed, which is based on the contact of two deflected elastic filaments under surface adhesion. Four fundamental fiber collapse modes (i.e., fiber-flat …

Information Surfing For Model-Driven Radiation Mapping, Andres Cortez, Herbert G. Tanner

Mechanical Engineering Faculty Publications

In this report we develop a control scheme to coordinate a group of mobile sensors for radiation mapping of a given planar polygon region. The control algorithm is based on the concept of information surfing, where navigation is done by means of following information gradients, taking into account sensing performance as well as inter-robot communication range limitations. The control scheme provably steers mobile sensors to locations at which they maximize the information content of their measurement data, and the asymptotic properties of our information metric with respect to time ensures that no local information metric extremum traps the sensors indefinitely. …

Computationally Efficient Modeling Of Transient Radiation In A Purely Scattering Foam Layer, Rudolph Scott Larson

Theses and Dissertations

An efficient solution method for evaluating radiative transport in a foam layer is a valuable tool for predicting the properties of the layer. Two different solution methods have been investigated. First, a reverse Monte Carlo (RMC) simulation has been developed. In the RMC simulation photon bundles are traced backwards from a detector to the source where they were emitted. The RMC method takes advantage of time reflection symmetry, allowing the photons to be traced backwards in the same manner they are tracked in a standard forward Monte Carlo scheme. Second, a reduced order model based on the singular value decomposition …

Modeling And Performance Evaluation Of Machining Spindle With Active Magnetic Bearings, Jerzy T. Sawicki, Eric H. Maslen, Kenneth R. Bischof

Mechanical Engineering Faculty Publications

Active magnetic bearings (AMBs) are increasingly employed in the machine tool industry to exploit their advantages over classical bearings such as high speed capability, rotation accuracy, high stiffness, and accurate displacement tracking capability. Furthermore, the possibility of on-line monitoring of the machining process (e.g., cutting force measurement, tool wear) makes AMB spindles very appealing to the High-Speed Machining (HSM) industry. Despite significant progress already reached in HSM technology, there remain numerous open challenges in modeling and control of magnetic bearings as applied to machining spindles. These include optimum control given AMB magnetic saturation levels, management of nonlinear effects, reduction of …

Determining Plastic Properties Of A Material With Residual Stress By Using Conical Indentation, J. Yan, Anette M. Karlsson, X. Chen

Mechanical Engineering Faculty Publications

Instrumented indentation is a popular method for determining mechanical properties in engineering materials. However, there are several shortcomings and challenges involved with correctly interpreting the test results. We propose here a unified method for evaluating instrumented indentation testing conducted on a material that exhibits both strain hardening under yielding and which is subjected to uniform, equi-biaxial residual stresses. The proposed method is based on extensive finite element simulations that relate the parameter-space spanned by Young’s modulus, yield strength, strain hardening and residual stress, to the response from the indentation test. Based on reverse analysis, the proposed method can be used …

Crack Growth Induced By Sonic Ir Inspection, John C. Chen, Jacob Kephart, Kyle Lick, William T. Riddell

Mechanical Engineering

We have developed an experiment to study the propagation of laboratory-synthesized fatigue cracks under various controlled conditions during Sonic IR inspection. The experiment provides for good repeatability in testing. The parameters of interest include the initial crack length, load history (stress intensity and load ratio) during crack generation, geometry of the crack, material and also the various conditions involving the ultrasonic excitation source. In general, we find that under typical sonic IR inspection conditions, the initial crack will propagate under sonic IR testing. The crack growth after each inspection event varies and exhibits a distribution in length of propagation. The …

Development And Evaluation Of A Simulation System Based Upon Standard Pedestrian Thoroughfare Methodologies, Charles O. Pringle

All Master's Theses

This study was undertaken to determine whether existing simulation and modeling systems could be used to analyze and model pedestrian traffic flows. The study incorporates the Highway Capacity Manual 2000 (HCM) (Transportation Research Board, National Research Council [TRB], 2000a) methodologies into a ProModel simulation and then compares and contrasts the results of the HCM calculations with the ProModel simulation.

Using Basic Computer Aided Drafting And Design Courses At The Freshman Level To Improve Technology Students Competitiveness In Obtaining Early Academic Career Internships, Anthony Dean, Mustafa Moustafa, Julie Moustafa

Engineering Technology Faculty Publications

Many students have the desire to have internships and part-time employment during their academic careers. Often students in their freshman and sophomore years in four year engineering and technology programs find it difficult to be competitive against more senior students for these positions. This paper discusses how students, in the Mechanical Engineering Technology (MET) program at ________________University, through taking CAD and Solid Modeling courses early in their academic careers are well suited to be competitive in obtaining internships and part time employment. This paper discusses the MET programs first two years’ curriculum and how it prepares the students to enter …

The Effect Of Cold Work On The Mechanical Behavior Of Niti Shape Memory Alloys, Mohamed Elwi Mitwally

Archived Theses and Dissertations

No abstract provided.

Vibration- Based Damage Detection Using Damage Location Vectors, Khaled Faizallah Mostafa

Archived Theses and Dissertations

No abstract provided.

Direct Simulations Of Cells Motions And Deformations In Flow, Quan Jin

Dissertations

Direct numerical simulations (DNS) are used to study the motions and deformations of blood cells, especially leukocytes, in pressure driven flows in parallel plate channels with both smooth and uneven walls under adhesion force between the leukocytes and the channel wall.

Leukocytes are represented by two composite fluid models. The first model is the compound-drop model in which the cytoplasm and the nucleus are modeled as fluids, and the second one is the drop-rigid-particle model in which the cytoplasm is modeled as a fluid and the nucleus as a rigid particle. The adhesion force is computed using two adhesion force …

Synthesis And Analysis Of Reactive Nanocomposites Prepared By Arrested Reactive Milling, Swati M. Umbrajkar

Dissertations

Different types of reactive nanocomposites have been synthesized by Arrested Reactive Milling (ARM). The technical approach was to increase the interface area available for heterogeneous reaction between solid fuel and oxidizer components. Using aluminum as the main fuel and different metal oxides as oxidizers, highly energetic reactive nanocomposites with different degrees of structural refinement were synthesized. Specifically, stoichiometric Al-MoO₃, Al-CuO, and Al-NaNO₃ material systems were studied in detail.

The correlation of heterogeneous exothermic reactions occurring in the nanocomposite powders upon their heating at low rates and ignition events observed for the same powders heated rapidly was of …

Rate-Dependent Slip Boundary Conditions For Simple Fluids, Nikolai V. Priezjev

Mechanical and Materials Engineering Faculty Publications

The dynamic behavior of the slip length in a fluid flow confined between atomically smooth surfaces is investigated using molecular dynamics simulations. At weak wall-fluid interactions, the slip length increases nonlinearly with the shear rate provided that the liquid/solid interface forms incommensurable structures. A gradual transition to the linear rate-dependence is observed upon increasing the wall-fluid interaction. We found that the slip length can be well described by a function of a single variable that in turn depends on the in-plane structure factor, contact density and temperature of the first fluid layer near the solid wall. Extensive simulations show that …