Engineering Commons^™

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 …

Design And Characterization Of A Dual-Stage, Thermally Actuated Nanopositioner, Neal B. Hubbard, Larry L. Howell

Faculty Publications

A nanopositioner is presented that has two stages for independent coarse and fine position control. Thermal microactuators operate both stages. The first stage includes a bistable mechanism: it travels 52 micrometers between two discrete positions. The second stage is mounted on the first stage and moves continuously through an additional 8 micrometers in the same direction as the first stage. Three approaches to the control of the second stage were evaluated in terms of accuracy and manufacturability, and one was selected for the design of the nanopositioner. The device was surface micromachined in a two-layer polysilicon process. Experiments were performed …

Modeling, Fabrication, And Optimization Of Niobium Cavities Final Phase: Final Report, Robert A. Schill Jr., Mohamed Trabia, William Culbreth

Transmutation Sciences Materials (TRP)

This final report provides the activities and accomplishments of Modeling, Fabrication, and Optimization of Niobium Cavities – Final Phase. The fluid flow experiments for the etching of the superconducting cavity walls and baffle designs of phase II of the three phases has been completed leading to a MS thesis in December of 2003. Designing the experimental setup of secondary electron emission was well underway in early summer of 2003 when funding was made available for this portion of the study. By March 2004, many of the components of the experimental study reached UNLV with some assembly accomplished. The first secondary …

Knowledge Representation, Organization, And Formalization For Simulation Modeling Of Discrete Manufacturing System, Jung Hung Ma

All-Inclusive List of Electronic Theses and Dissertations

Simulation is an useful tool that helps managers making decision by designing models for real systems. It helps companies to study behaviors of real systems hy analyzing computer models and improve the systems based on the experiments' results. However, cross-domain knowledge requirement and lack of tools facilitate modeling are the main reasons that make industries hesitate to use simulation to assist making decision. This research is an attempt to develop robust knowledge representations for discrete manufacturing system and conceptual simulation model. A modeling methodology was proposed to utilize these knowledge representations (KRs) for developing conceptual simulation models from application domain …

Decentralized Perimeter Surveillance Using A Team Of Uavs, Timothy Mclain, Randal W. Beard, Derek Kingston, Ryan S. Holt, David W. Casbeer

Faculty Publications

This paper poses the cooperative perimeter-surveillance problem and offers a decentralized solution that accounts for perimeter growth (expanding or contracting) and insertion/deletion of team members. By identifying and sharing the critical coordination information and by exploiting the known communication topology, only a small communication range is required for accurate performance. Simulation and hardware results are presented that demonstrate the applicability of the solution.

Incorporating Computational Fluid Dynamics Into The Preliminary Design Cycle, Jonathan Knighton Shelley

Theses and Dissertations

Industry is constantly looking for ways to bring new or derivative products to market in the shortest amount of time for the least amount of money. To accomplish this, Industry has adopted Computer Aided Engineering (CAX) tools that perform structural, flow, manufacturing, and cost analysis. The way in which a company utilizes these CAX tools can determine the success of these new products. One of these tools that Industry often struggles with in the preliminary design of a product is Computational Fluid Dynamics (CFD). Some of the challenges presented by CFD are the time it takes to create a CAD …

High Temperature Heat Exchanger Project: Quarterly Progress Report April 1, 2005 Through June 30, 2005, Anthony Hechanova

Publications (NSTD)

Quarterly Collaboration Meeting. General Atomics hosted a UNLVRF HTHX Project quarterly meeting on June 5 in San Diego, California. The purpose of the meeting was to promote collaboration and communication among the UNLV Research Foundation partners. Collaborators had the opportunity to discuss their research program plan and update their progress. The next meeting will be in September in Berkeley hosted by UC Berkeley.

HTHX Computational Design (UNLV). Work on optimizing the ceramic offset strip in compact HTHX design through parametric studies was performed and completed. A simple single channel model was used to perform parametric studies on dimensions and flow …

Stability Analysis For Forging Of Porous Bodies, Xuan Wang, Eugene Olevsky, Alain Molinari

Industrial and Manufacturing Engineering

The continuum theory of sintering is used for the analysis of the stability of forging of a cylindrical powder specimen. The constitutive properties of the powder material are assumed to follow a power-law creep relationship. Temperature-coupled linear non-uniform stability analyses are carried out. Stability maps are obtained for forging of copper powder components.

Nesting Automated Design Modules In An Interconnected Framework, Jared Matthew Young

Theses and Dissertations

This thesis seeks to extend the PDG methodology by developing a generalized formal method for nesting PDGs in an interconnected system. A procedure for decomposing an individual PDG into reusable modules will be defined and a software architecture will be presented which takes advantage of these reusable modules. This method breaks the PDG structure into discrete elements known as PDG objects, PDG modules and PDG services. Each of these elements forms a distinct unit of reuse and each can be seen as a "little" PDG. Two different industrial implementations of this method are presented. These examples show that it is …

Experimental And Numerical Investigation Of Tool Heating During Friction Stir Welding, Joshua L. Covington

Theses and Dissertations

The heat input to the tool has been investigated for friction stir welding (FSW) of aluminum alloy AL 7075-T7351 over a wide range of process operating parameters using a combined experimental/numerical approach. In a statistical Design of Experiments fashion, 54 experimental welds (bead-on-plate) were performed at 27 different parameter combinations. Measured outputs during each of the welds included forces in all three coordinate directions and internal temperature of the rotating tool at three locations near the tool/workpiece interface. The heat input to the tool was also identified for each weld using infrared imaging temperature measurement techniques and the portion of …

Visualizing And Interacting With Externally Coupled Engineering Analysis Results, Paul Frederick Nelson

Theses and Dissertations

Visualizing and interacting with engineering analysis results can provide valuable insights into a system's performance and aid in engineering decision-making. Currently, the majority of analysis codes are developed as isolated solutions focusing only on the most prominent physical influence to a system, such as thermal, structural, fluid, etc. Frequently, more than one of these physical influences combined to force engineers to evaluate complex, coupled systems. Coupled analysis codes are becoming more common place tools for engineers demanding high fidelity simulations of complex systems. External code coupling solutions are emerging to permit generic coupling of separate, world class CAE solvers thus …

Development Of A Weatherproof Windscreen For A Microphone Array, Jeffrey R. Hill

Theses and Dissertations

Microphone windscreens are typically used to reduce the noise associated with wind flowing over a microphone diaphragm by reducing the velocity of the airflow. While most windscreens are effective at reducing this noise, they do not protect the microphone from many natural elements, such as moisture, sand, and other small particles. The focus of this research was to design a windscreen that protects an array of five microphones located around a 4.5-inch diameter cylinder from these natural elements. The design goals were to have a wind noise attenuation of at least 8 dB, an insertion loss of less than 1 …

System And Device For Characterizing Shape Memory Alloy Wires, Robert Ryan Vallance, Bruce L. Walcott, James E. Lumpp, Sumanth Chikkamaranahalli, Osamah A. Rawashdeh, Eric Wolsing

Mechanical Engineering Faculty Patents

Instruments and methods for measuring a property of a shape memory alloy are provided. The instrument includes a base plate, a non-contact movable mass, a force gauge, an actuator, a biasing spring, a heater for heating the shape memory alloy, and a non-contact displacement detector. The biasing spring and the shape memory alloy are disposed whereby a force applied thereby is applied substantially through a center of stiffness of the movable mass. The displacement detector measures a displacement of the movable mass in a colinear direction with a direction of movement of the movable mass and with a direction of …

Integrating Value Stream Mapping And Simulation, Michelle E. Scullin

Theses and Dissertations

An important principle in Lean manufacturing, value stream mapping (VSM) can be helpful in understanding how process flow and information flow affect each other. A VSM is a static picture of a process that allows the user to see where value is added into the value stream. Simulation is used to evaluate the behavioral issues of processes. In a manufacturing realm this means simulation shows how each operation affects other operations so determinations can be made about where bottlenecks or other problems exist in the process. Theoretically, the integration of VSM and Simulation can aide in process improvement by showing …

Ortho-Planar Mechanisms For Microelectromechanical Systems, Craig P. Lusk

Theses and Dissertations

A method for representing the design space of ortho-planar mechanisms has been developed. The method is based on the Theorem of Equality of Orientation Set Measures (TEOSM) which allows mechanisms to be represented by points in an abstract space. The method is first developed for single loop planar folded mechanisms with revolute joints, and later extended to mechanisms with prismatic joints and to spherical folded mechanisms. Functions which assign a value to each point in design space can be used to describe classes of mechanisms and evaluate their utility for MEMS design. Additionally, this work introduces the use of spherical …

Vision-Based Target Localization From A Small, Fixed-Wing Unmanned Air Vehicle, Joshua D. Redding

Theses and Dissertations

Unmanned air vehicles (UAVs) are attracting increased attention as their envelope of suitable tasks expands to include activities such as perimeter tracking, search and rescue assistance, surveillance and reconnaissance. The simplified goal of many of these tasks is to image an object for tracking or information-gathering purposes. The ability to determine the inertial location of a visible, ground-based object without requiring a priori knowledge of its exact location would therefore prove beneficial. This thesis discusses a method of localizing a ground-based object when imaged from a fixed-wing UAV. Using the target's pixel location in an image, with measurements of UAV …

Evaluation Of Accuracy And Efficiency Of Some Simulation And Sampling Methods In Structural Reliability Analysis, Christopher D. Eamon, Michel D. Thompson, Zhenyu Liu

Civil and Environmental Engineering Faculty Research Publications

Numerous simulation and sampling methods can be used to estimate reliability index or failure probability. Some point sampling methods require only a fraction of the computational effort of direct simulation methods. For many of these methods, however, it is not clear what trade-offs in terms of accuracy, precision, and computational effort can be expected, nor for which types of functions they are most suited. This study uses nine procedures to estimate failure probability and reliability index of approximately 200 limit state functions with characteristics common in structural reliability problems. The effects of function linearity, type of random variable distribution, variance, …

Enhancing Student Learning In Mechanics Through Rapid-Feedback, Jennifer Kadlowec, John Chen, Dexter Whittinghill

Mechanical Engineering

In this project our goal is to improve student learning in engineering mechanics courses. The aim to improve learning was accomplished by providing rapid feedback to students of their understanding of key concepts and skills being taught. The feedback system acts as a catalyst to encourage students, working in pairs, to assist each other in correcting misconceptions or deepening each other’s understanding of the concept or skill at hand. Furthermore, the system allows the professor to assess the students’ level of comprehension or misconception in a just-in-time fashion, and thus guide the pace of covering the material. The feedback is …

Flexible Roofing Facility: 2004 Summer Test Results, Florida Solar Energy Center, Danny Parker

FSEC Energy Research Center®

The Flexible Roof Facility (FRF) is a test facility in Cocoa, Florida designed to evaluate five roofing systems at a time against a control roof with black shingles and vented attic (Figure E-1). Since 1989 the testing has evaluated how roofing systems impact summer residential cooling energy use and peak demand. In the summer of 2004, the following roofing systems were tested. Materials tested were: Galvalume® unfinished (unpainted) 5-vee metal with vented attic (3rd year of exposure), galvanized unfinished 5-vee metal with vented attic (3rd year of exposure, black shingles with standard attic ventilation (Control Test Cell), white standing seam …

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. …

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 …

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 …

Design And Fabrication Of A Prototype Fabry-Perot Cavity For The Compton Polarimeter Upgrade At Jefferson Lab, Deepa Deepa

Mechanical & Aerospace Engineering Theses & Dissertations

Upcoming experiments at Hall A at Jefferson lab require 1 % absolute accuracy of the electron beam polarization measurement at 0.85 Ge V energy. The Compton polarimeter at Hall A is capable of measuring beam polarization with 3 - 4 % accuracies at this beam energy. Hence it was proposed to upgrade the present Compton by doubling the laser frequency [2]. The present Compton polarimeter operates with a 1064 nm, continuous wave laser at 200 mW. This power is enhanced to 1.5 kW using a 0.85 m long Fabry-Perot Cavity. Changing to 532 nm laser with the same power would …

Mechanics Of Hydrogenated Amorphous Carbon Deposits From Electron-Beam-Induced Deposition Of Paraffin Precursor, W. Ding, D. A. Dikin, X. Chen, R. D. Piner, R. S. Ruoff, E. Zussman, X. Wang, Xiaodong Li

Faculty Publications

Many experiments on the mechanics of nanostructures require the creation of rigid clamps at specific locations. In this work, electron-beam-induced deposition(EBID) has been used to depositcarbonfilms that are similar to those that have recently been used for clamping nanostructures. The film deposition rate was accelerated by placing a paraffin source of hydrocarbon near the area where the EBIDdeposits were made. High-resolution transmission electron microscopy, electron-energy-loss spectroscopy, Raman spectroscopy, secondary-ion-mass spectrometry, and nanoindentation were used to characterize the chemical composition and the mechanics of the carbonaceous deposits. The typical EBIDdeposit was found to be hydrogenated amorphous carbon (a-C:H) having …

Investigation And Applications Of Latin Hypercube Sampling Methods, Prashant K. Patel

Mechanical & Aerospace Engineering Theses & Dissertations

The Latin hypercube sampling method, sometimes called the stratified sampling method, is a commonly used variance reduction method. Recently, the optimal Latin hypercube sampling method (OLH) and the modified optimal Latin hypercube sampling method (MOLH) are introduced in the literature, which use the genetic algorithm to adjust the distance between sampled points.

This paper will compare the basic Latin hypercube, the optimal Latin hypercube and the modified optimal Latin hypercube methods for generating the sample points for statistical application and curve fitting, in te1ms of accuracy and efficiency. Analytical and structural examples are used in this thesis to facilitate the …

An Analysis Of Microstructure And Corrosion Resistance In Underwater Friction Stir Welded 304l Stainless Steel, Tad Dee Clark

Theses and Dissertations

An effective procedure and parameter window was developed for underwater friction stir welding (UWFSW) 304L stainless steel with a PCBN tool. UWFSW produced statistically significant: increases in yield strengths, decreases in percent elongation. The ultimate tensile strength was found to be significantly higher at certain parameters. Although sigma was identified in the UWFSWs, a significant reduction of sigma was found in UWFSWs compared to ambient FSWs. The degree of sensitization in UWFSWs was evaluated using double loop EPR testing and oxalic acid electro-etched metallography. Results were compared to base metal, ambient FSW, and arc welds. Upper and lower sensitization localization …

Attribution Standardization For Integrated Concurrent Engineering, Tyson J. Baker

Theses and Dissertations

Product design is a creative process, often subject to rapid and numerous design change requirements. To facilitate geometric redesign iterations, Parametric Computer-Aided Design CAD) systems were introduced. To manage the numerous product design iterations produced by parametric CAD systems, Product Data Management (PDM) systems were developed to capture, document, and manage each product revision. PDM has proved effective thus far at managing design history. However, PDM is built upon database management systems (DBMS), which have the capability of doing far more than simply managing product revision history. Product data consists not only of the physical geometry used to describe it, …

Two-Dimensional Grain Boundary Percolation In Alloy 304 Stainless Steel, Brent L. Adams, John A. Basinger, David T. Fullwood, E. R. Homer

Faculty Publications

This work was supported by the MRSEC program of the National Science Foundation under Award Number DMR-0079996. An experimentally-obtained percolation threshold for high-angle random grain boundary networks in alloy 304 stainless steel is compared to thresholds predicted by percolation theory. A discrepancy occurs in the two values (0.46 experimental and 0.65 theoretical). Possible reasons for the discrepancy are explored. The grain boundary network appears to be composed of two distinct sub-networks, with the 'outer' network acting as the dominant contributor to the percolating paths.

An Investigation Of Contact Path And Kinematic Error Of Face-Gear Drives, Tsang-Dong Chung, Yun-Yuan Chang

Journal of Marine Science and Technology–Taiwan

Based on the face-gear generation process, the analytical geometry of face-gear drive with its mathematical model for tooth contact analysis of face-gear and spur pinion meshing was derived. In this paper, contact path and transmission error due to assembly misalignment are analyzed by using the proposed mathematical model and the tooth contact analysis. The effects of assembly error along the axis of face-gear, misalignment of crossed and angular displacement between axes of a spur pinion and a face-gear are all investigated. The results are illustrated by several examples

Collaborative Experimentation And Simulation: A Pathway To Improving Student Conceptualization Of The Essentials Of System Dynamics And Control Theory, Javier A. Kypuros, Thomas J. Connolly

Mechanical Engineering Faculty Publications and Presentations

The overarching goal of this research is to improve conceptualization of System Dynamics and Controls concepts by incorporating a Web-facilitated curriculum to enable intercampus collaboration and remotely-accessible or virtual systems. This approach will complement lecture-based curricula and will strongly enhance students’ conceptualization and exposure to System Dynamics and Controls fundamentals by providing less restricted exposure to a variety of systems that encompass the more important Dynamic Systems concepts. The plan involves the development of a System Dynamics Concepts Inventory and the implementation and assessment of three Web-enabled laboratory formats: (1) inter-campus collaborative experimentation, (2) remotely-accessible experiments, and (3) virtual system …