Mechanical Engineering Commons^™

Mar 2004, Tractor Museum

Lester F. Larsen Tractor Museum: Planning and Development Documents

Curator's Report Director's Report Treasurer's Report

Coordinated Uav Target Assignment Using Distributed Calculation Of Target-Task Tours, David H. Walker

Theses and Dissertations

This thesis addresses the improvement of cooperative task allocation to vehicles in multiple-vehicle, multiple-target scenarios through the use of more effective preplanned tours. Effective allocation of vehicles to targets requires knowledge of both the team objectives and the contributions that individual vehicles can make toward accomplishing team goals. This is primarily an issue of individual vehicle path planning --- determining the path the vehicles will follow to accomplish individual and team goals. Conventional methods plan optimal point-to-point path segments that often result in lengthy and suboptimal tours because the trajectory neither considers future tasks nor the overall path. However, cooperation …

A Comprehensive Model For Technology Push Product Development, Gregory Loren Bishop

Theses and Dissertations

Successful product development has been a fundamental part of many of today's companies and their continued prosperity depends on continuing to develop new products in the future. There are many models of product development. The two most common classes of development are market pull (MP) and technology push (TP). TP product development differs from MP in that the development begins with a specified technology rather than a specified customer. Because TP development is generally considered more difficult and challenging, most of the product development research has focused on MP development and many researchers and practitioners favor MP development over TP …

The Contextable: Building And Testing An Intelligent, Context-Aware Kitchen Table, Daniel Matthew Hoopes

Theses and Dissertations

The purpose of this thesis was to design and evaluate The ContexTable, a context-aware system built into a kitchen table. After establishing the current status of the field of context-aware systems and the hurdles and problems being faced, a functioning prototype system was designed and built. The prototype makes it possible to explore established, untested theory and novel solutions to problems faced in the field.

High-Torque Capacity Compliant Centrifugal Clutches, Ryan G. Weight

Theses and Dissertations

This thesis developed high-torque-capacity floating opposing arm clutches that are manufactured with standard economical manufacturing processes, while maintaining critical performance characteristics. Contact engagement speed and torque capacity models were created for the Hoffco-Comet, floating-opposing-arm (FOA), and floating 1 (F1) clutches. Sensitivity analyses were performed to identify key design parameters. A robust compliant FOA clutch was designed by minimizing the tolerance for both contact engagement speed and torque capacity. The robust design insures that the clutch will operate within the prescribed application constraints. Additional modeling showed that using a layered clutch would significantly tighten the contact engagement speed and torque performance …

Percolation Paths Of Three-Dimensions In Sensitized Stainless Steel, Alisa Jean Henrie

Theses and Dissertations

The study of three-dimensional percolation paths through materials is important in its contribution to understanding defect sensitive properties of materials. This work shows the importance of grain boundary character in modeling defect sensitive boundaries. Also presented are trends of percolation of sensitized grain boundaries in 304 stainless steel (304SS). Of particular interest is how open paths form in a three-dimensional model created through serial sectioning. Evidence is presented that triple or quadruple points that contain typically two boundaries with special character that intersect the percolation path break up the path. Some grains with no known special qualities (i.e., CSL) have …

Synthesis Of Tin Oxide Nanostructures With Controlled Particle Size Using Mesoporous Frameworks, A. Cabot, J. Arbiol, E. Rossinyol, J. R. Morante, Fanglin Chen, Meilin Liu

Faculty Publications

Tin oxide nanostructures with controlled narrow particle size distribution were synthesized inside silica mesoporous templates. In this way, particle growth was blocked by physically corseting the tin compound inside the silica frameworks, the pore diameter of which determines the final tin oxide crystallite size distribution. Template structures were subsequently eliminated by chemical methods to collect the unsupported semiconductor nanoparticles. Thus obtained tin oxed nanopowders, with particle sizes in the range between 6 and 10 nm, were structurally, chemically, and electically characterized. The results are compared with those obtained from the characterization of larger crystallite materials.

Standards For Clean Air Florida Homes, Florida Solar Energy Center, Subrato Chandra

FSEC Energy Research Center®

These standards are designed for new, slab on grade homes built in Florida. Changes to the standards may be necessary for other house construction types. These standards are not meant to be exclusionary. The home builder may submit alternative materials or design details which will result in equivalent performance. These standards complement all building codes and do not supersede any codes.

Thin Film Encapsulation Of Radio Frequency (Rf) Microelectromechanical Systems (Mems) Switches, Eric D. Marsh

Theses and Dissertations

Microelectromechanical systems (MEMS) radio frequency (RF) switches have been shown to have excellent electrical performance over a wide range of frequencies. However, cost-effective packaging techniques for MEMS switches do not currently exist. This thesis involves the design of RF-optimized encapsulations consisting of dielectric and metal layers, and the creation of a novel thin film encapsulation process to fabricate the encapsulations. The RF performance of several encapsulation designs are evaluated with an analytical model, full wave electromagnetic simulation, and laboratory testing. Performance degradation due to parasitic and reflection losses due to the package is considered, and RF feed-throughs of the transmission …

Demonstrating Optothermal Actuators For An Autonomous Mems Microrobot, Francis R. Szabo

Theses and Dissertations

There are numerous applications for microrobots which are beneficial to the Air Force. However, the microrobotics field is still in its infancy, and will require extensive basic research before these applications can be fielded. The biggest hurdle to be solved, in order to create autonomous microrobots, is generating power for their actuator engines. Most present actuators require orders of magnitude more power than is presently available from micropower sources. To enable smaller microrobots, this research proposed a simplified power concept that eliminates the need for on-board power supplies and control circuitry by using actuators powered wirelessly from the environment. This …

A False Acceptance Error Controlling Method For Hyperspherical Classifiers, Chen-Wen Yen, Chieh-Neng Young, Mark L. Nagurka

Mechanical Engineering Faculty Research and Publications

Controlling false acceptance errors is of critical importance in many pattern recognition applications, including signature and speaker verification problems. Toward this goal, this paper presents two post-processing methods to improve the performance of hyperspherical classifiers in rejecting patterns from unknown classes. The first method uses a self-organizational approach to design minimum radius hyperspheres, reducing the redundancy of the class region defined by the hyperspherical classifiers. The second method removes additional redundant class regions from the hyperspheres by using a clustering technique to generate a number of smaller hyperspheres. Simulation and experimental results demonstrate that by removing redundant regions these two …

Development Of Commercially Viable Compliant Mechanisms Using The Pseudo-Rigid-Body Model: Case Studies Of Parallel Mechanisms, Christopher A. Mattson, Larry L. Howell, Spencer P. Magleby

Faculty Publications

Analysis and synthesis of compliant mechanisms has recently been the subject of significant study in the research community. This focus has led to a number of design approaches for developing compliant mechanisms. This paper describes the value of using the Pseudo-Rigid-Body Model (PRBM) to design compliant mechanisms for commercial products. Application of the PRBM is illustrated through the development of two parallel mechanisms: a bicycle derailleur and parallel-motion bicycle brakes. The PRBM allows compliant mechanisms to be modeled and analyzed as rigid-body mechanisms and significantly reduces the complexity of analysis. Mechanisms with straightforward properties are used to demonstrate the use …

Male Breast Cancer During Finasteride Therapy [4], Shen C. Lee, Robert J. Ellis

Mechanical and Aerospace Engineering Faculty Research & Creative Works

No abstract provided.

Unveiling The Crucial Role Of Impact Nergy Loss For So-Called Incompressible Fluid Flow, Jiunn-Shean Chiang, Shu-Hao Chuang, Hsing-Juin Lee

Journal of Marine Science and Technology–Taiwan

Experiments show that pipe flows with large expansion angle and area ratio always accompany with significant amount of energy loss, actually energy loss ratios over 70% of incoming flow kinetic energy are commonplace. It is generally believed that all the energy loss is entirely due to viscous dissipation effect. In this paper, several interesting demonstrations have been given to prove the existence and importance of impact energy loss. Literally, impact energy loss is usually more important than viscous energy loss in many cases. In fact, the pipe expansion flow can be configured as high-speed flow ramming into low-speed flow and …

Surface States In Template Synthesized Tin Oxide Nanoparticles, A. Cabot, J. Arbiol, R. Ferre, J. R. Morante, Fanglin Chen, Meilin Liu

Faculty Publications

Tin–oxide nanoparticles with controlled narrow size distributions are synthesized while physically encapsulated inside silica mesoporous templates. By means of ultraviolet-visible spectroscopy, a redshift of the optical absorbance edge is observed. Photoluminescence measurements corroborate the existence of an optical transition at 3.2 eV. The associated band of states in the semiconductor gap is present even on template-synthesized nanopowders calcined at 800 °C, which contrasts with the evolution of the gap states measured on materials obtained by other methods. The gap states are thus considered to be surface localized, disappearing with surface faceting or being hidden by the surface-to-bulk ratio decrease.

Effects Of Friction Stir Welding On Polymer Microstructure, Seth R. Strand

Theses and Dissertations

This work establishes the relationships between several key Friction Stir Welding process parameters and the resulting microstructural and flexural properties of the welded joint. A series of four single parameter experiments were run. The parameters investigated were pin diameter, feedrate, shoe temperature, and pressure time. Butt welds were made in 6 mm thick stress-relieved extruded polypropylene sheet. Three-point bend tests were used to determine the ultimate flexural strength and coincident strain. The maximum bend angle before failure was used to label the welds as "good or bad." An optical microscope capable of cross polarization was used to examine and photograph …

Alleviating Moisture Problems Hot, Humid Climate Housing, Florida Solar Energy Center, Subrato Chandra

FSEC Energy Research Center®

The Southeastern U.S. experiences hot, humid conditions throughout the summer months and in Florida, one of the high growth states with large number of homes, these conditions can prevail throughout most of the year. As a result it is not uncommon to find extensive mold, soft drywall, buckled floors, damaged ceilings and other moisture problems in new and existing site built and manufactured homes. Since 1999, as a result of participation in the U.S. DOE funded Building America program, the authors have developed first hand experience and conducted research in these areas. This paper provides a brief summary of the …

Sensitivity Analysis Of Hill Muscle Parameters, Janet Brelin-Fornari, Paras Shah, Mohamed El-Sayed

Mechanical Engineering Presentations And Conference Materials

A computational, rigid body model of a 50^th percentile male head and neck utilizing 15 Hill Muscle pairs is used to study the sensitivity of Hill Muscle Model parameters. A 15g linear acceleration is applied within the transverse plane at the lowest vertebral level of the neck (T1). The resultant linear acceleration of the head is analyzed. In response is minimally affected. The peak accelerations did change, and in the case of varying muscle activation, the peak acceleration changed significantly, 36%. Each of the other parameter variations affected the peak acceleration of the head by less than 5%. Overall, …

Effect Of Fullerene Containing Lubricants On Wear Resistance Of Machine Components In Boundary Lubrication, Andriy Titov

Dissertations

Fullerenes, a new form of carbon nanomaterials, possess unique physical and mechanical properties that make their use as additives to liquid lubricants potentially beneficial. The goal of this study was to investigate the effect of fullerene containing lubricants on wear resistance of steel-bronze couples operating under boundary lubrication conditions. A mathematical model of deformed asperity contact was built to calculate real contact area and real contact pressure. Computer controlled wear friction testing methodology and equipment were designed, developed and implemented for obtaining reliable and objective experimental data. In addition, optical and scanning electron microscopy and standard surface texture analysis were …

Migration Of An Intruder Particle In A Boundary Driven Shear Flow, Jian Liu

Dissertations

This study reports on three-dimensional, discrete element simulations of a single large spherical intruder in a Couette shear flow composed of uniform sized particles. The simulation results are useful in providing a numerical reproduction of the experiments for size segregation and mixing. This in turn has a major importance in many industries which are concerned with handling of particles and powders, such as pharmaceutical manufacturing, agriculture, chemical and mineral processing.

Discrete element simulations are carried out using the "soft sphere" model of Walton, et. al., which provides a method for obtaining the information at a macroscopic level from multi-body collisions …

Vibration-Induced Densification Of Granule Materials, Ninghua Zhang

Dissertations

Physical experiments as well as discrete element simulations of vibration are carried out. The use of different amplitudes and frequencies are applied in the experiments to facilitate the observation of densification trends with mono-disperse acrylic spheres and multi-disperse polyethylene pellets. For mono-disperse acrylic spheres, four densification trends are found at different vibration conditions, and attaining the "maximum density" is closely related to the combination of vibration frequency and amplitude, in agreement with experiments in the literature. For multi-disperse polyethylene pellets, there is a substantial increase in solids fraction due to the effects of particle shape and surface friction. Computer simulations …

Dielectrophoretic Manipulation Of Biological And Non-Biological Analytes In A Microfluidic Channel, Dawn J. Bennett

Dissertations

Micro-total-analytical systems (μTASs) for analyzing chemical/biological substances are now used across a wide variety of applications ranging from biological warfare agent detection to the healthcare industry. The first step in the operation of a μTAS consists of concentrating and separating the analytes of interest from the background matrix and positioning them into selected locations for subsequent analysis. The use of ac electric fields was demonstrated to have promising potential for a μTAS because the application of an ac field suppresses undesirable electrolytic effects in the liquid. The main purpose of this work is to study micro-scale phenomena in a flowing …

Combustion Of Aerosolized Spherical Aluminum Powders And Flakes In Air, Binu Zacharia Eapen

Theses

Combustion rates and completeness of aerosolized spherical aluminum powders and flakes are compared using constant volume explosion experiments. The comparison of particles and flake sizes was made based on their specific surface areas determined using the Brunauer-Emmett-Teller (BET) method and respective "BET diameters". It is observed that the rates of pressure rise and rates of flame propagation were higher for aluminum powders with BET diameters of about 2 to 5 μm compared to aluminum flakes for which the BET diameters were under 1 μm In agreement with the flame propagation rates, the overall completeness of combustion was also higher for …

Characterization Of Aluminum Powder Ignition, Salil Mohan

Theses

Heating rate effect and particle size effect on ignition temperature of Al powder were studied to collect data for development of a possible Al powder ignition model. Aluminum ignition is associated with a highly accelerated burn rate and high combustion enthalpy. A new ignition model, which can adequately interpret these conditions, is needed to develop better propulsion fuels, explosives and incendiaries that use Al as an additive. This experimental program was focused on preparing framework for characterization of ignition kinetics of Al powder by determining the ignition temperature for different, systematically varied, heating rates and particle size. The experimental setup …

Magneto-Rheological Fluid Orthosis For Suppressing Tremor, Hyoung-Joo Yeo

Theses

Tremor is a common movement disorder that occurs with specific neurological conditions. This condition may seriously impact daily living activities. The aim of the present study is to evaluate the possibility of the development of a wearable technology that is capable of exerting torques at a user's joints for suppressing tremor.

This thesis is based on the concept of "smart structures" which are made of Magneto-Rheological (MR) fluid that can dynamically alter its viscosity under magnetic field. The wearable tremor suppressing orthosis needs several conditions. It should be safe, light weight, simple and small in structure, and easily attachable. An …

On The Microstructural Development In Platinum-Modified Nickel-Aluminide Bond Coats, S. Darzens, Anette M. Karlsson

Mechanical Engineering Faculty Publications

A numerical procedure for simulating the distortions exhibited by a thermally grown oxide (TGO) upon temperature cycling has been adapted to incorporate the microstructure of the bond coat. The focus is on the dual phase β/γ′ microstructure that develops upon oxidation of a system with a Pt-aluminide bond coat. The results reveal that the presence of the γ′-phase next to the TGO reduces its distortion locally, because of the superior high-temperature strength of γ′, relative to β. Conversely, in regions where the β-phase exists adjacent to the TGO, it distorts and the TGO propagates downward, while simultaneously lengthening. These results …

High Temperature Heat Exchanger Project (Hthx) Project Quarterly Report, University Of Nevada, Las Vegas. Research Foundation

Publications (NSTD)

On October 24, 2003, the University of Nevada, Las Vegas (UNLV) hosted an all-day HTHX Kickoff Meeting attended by all participating institutional representatives and researchers. Objectives of this meeting were to identify near-term research objectives, coordinate collaborative activities, and identify required urgent action items.

A Virtual Reality Environment For Multi-Sensor Data Integration, Scott Papson, Joseph Oagaro, Robi Polikar, John Chen, John L. Schmalzel, Shreekanth Mandayam

Mechanical Engineering

Virtual reality (VR) has typically found applications in industrial design, rapid prototyping and advanced scientific visualization. In this paper, we investigate the use of VR for multi-sensor data integration. We attempt to demonstrate that multiple data types-graphical, functional and measurement can be effectively combined inside of a VR environment. This platform allows the user to rapidly sift through large and complex data sets and isolate features of interest. Furthermore, VR environments can be made to evolve based on system data and user input-this provides the ability to develop scenarios that can be used to make informed decisions. Results demonstrating the …

Jan 2004, Tractor Museum

Lester F. Larsen Tractor Museum: Planning and Development Documents

NE Museum Budget Cuts Selling Farmall H Husker Harvest Days

Florida's Energy Future: Opportunities For Our Economy, Environment And Security - Executive Summary, Florida Solar Energy Center, Philip W. Fairey

FSEC Energy Research Center®

The future of Florida's economy, environment and security is inextricably intertwined with our energy use decisions. Our state has one of the nation's fastest growing populations, promoting rapid expansion of an energy industry that imports its fuel supplies. Florida exports approximately $32 billion per year for these energy fuels. Moreover, the Florida economy depends critically on tourism and agriculture, and the fuels and energy products that maintain them. Our pristine environment is the primary natural resource supporting this unique economic engine and the adverse effects of our rapidly growing energy use now stress it. Our State's economic well-being and security …