Engineering Commons^™

Crash Attenuation System, John D. Reid, John R. Rohde, Dean L. Sicking

Department of Mechanical and Materials Engineering: Faculty Publications

A crash attenuation system having an impact head, and energy absorption mechanism. The energy absorbing mechanism has a mandrel for rupturing thin-walled tubes in a controlled rupture to absorb impact forces from a colliding vehicle. A frame may be used to mount the system to a truck, trailer, guardrail, median barrier end treatment, or a crash cushion. Stress concentrators may be incorporated into the tubes and the mandrels to selectively control rupturing and energy dissipation.

An Analysis Of Greenhouse Cookpot Design Considerations For Low-Cost Solar Cookers, Florida Solar Energy Center, Philip W. Fairey

FSEC Energy Research Center®

This analysis is prepared as part of a research project on low-cost solar cookers conducted by the Florida Solar Energy Center for the Dorothy Ann Foundation on behalf of Solar Household Energy, Inc. The overall purpose of the research project is to improve the performance, reliability and cost-effectiveness of low-cost solar cookers for use in developing nations. The analysis reported here concentrates solely on the cookpot and "greenhouse" design considerations for such systems.

Lightweight Cigs2 Thin-Film Solar Cells On Stainless Steel Foil, Florida Solar Energy Center, Neelkanth Dhere

FSEC Energy Research Center®

AM 0 PV parameters of large-grain, {112} orientated chalcopyrite CIGS2 thin films solar cells on 127µm thick SS flexible foil for space power were: V_oc = 802.9 mV, J_sc = 25.07 mA/cm², FF = 60.06%, and efficiency 0 = 8.84%. Detailed current versus voltage analysis gave values of series resistance Rs, shunt resistance Rp, diode factor A, and reverse saturation current Jo of ~0.1 Ω cm2, ~600 Ω cm2, ~2.2 and ~1.85x10^-8 A cm^-2 respectively. A sharp QE cutoff was observed at CIGS2 bandgap of ~1.50 eV. Higher foil roughness resulted in a preliminary …

Oct 2001, Tractor Museum

Lester F. Larsen Tractor Museum: Planning and Development Documents

Software Program Storage Space Needed 16 new members

Automatic Compact Disc Transfer For Quality Assurance Testing, Ravi P. Ramachandran, John Chen, Linda M. Head, John L. Schmalzel, Hampton C. Gabler

Mechanical Engineering

The purpose of this project was to design, build and test a low cost prototype that transfers compact discs (CDs) from a spindle to a computer based testing station. This will speed up the CD production/testing interface and eliminate the need for manual operation. Along with a heavy product design technical component, the project included a real life educational experience for the four students who got credit for a one year advanced senior project. Various designs were considered and the optimal design (based on cost and performance) was prototyped.

Fabrication Of 2- And 3-Dimensional Nanostructures, Hong Jiang, Camelia N. Borca, Bo Xu, Brian W. Robertson

Department of Mechanical and Materials Engineering: Faculty Publications

Amongst tools for fabricating periodic and aperiodic nanostructures and nanodevices, electron beam-induced organometallic chemical vapor deposition (E-OMCVD) offers a highly flexible and controllable one-step deposition process. E-OMCVD enables maskless fabrication of nanoscale research and custom structures that have least dimensions near or below 10 nm–a scale at which other methods prove difficult or costly. Using the focused electron beam in a modified HB501 field-emission scanning transmission electron microscope (STEM), pads and wires with uniform thickness and well-defined shapes have been defined and deposited. Although conditions for fabricating the smallest deposits have not yet been optimized, the edge acuity (sharpness) of …

Study Of Delamination In Acceleration Tested Pv Modules, Florida Solar Energy Center, Neelkanth Dhere

FSEC Energy Research Center®

The average adhesional shear strength at silicon cell/EVA interface in damp-heat, acceleration-tested modules was ~27% of that measured in new modules. The average carbon concentration at the surface of samples extracted from acceleration tested modules was 15 atomic % or ~30% of that measured in new modules. Surface concentrations of sodium on Si-cell samples from the acceleration tested modules ranged from 4.9 to 22.0 atomic %while those of phosphorous ranged from 4.3 to 7.1 at. %. These are very high impurity concentrations. Often small concentrations of phosphorous were detected at the interface between titanium oxide antireflection coating and silicon cell. …

Ole Miss Engineer 2001

Ole Miss Engineer

No abstract provided.

Investigation Of Dual-Mode Combustion With Large Upstream Interaction, Melanic Olynciw-Mills

Mechanical & Aerospace Engineering Theses & Dissertations

Dual-mode scramjet combustor configuration with significant upstream interaction is investigated numerically. The possibility of scaling the domain to accelerate the convergence an3 reduce the computational time is explored. The supersonic combustor configuration was selected to provide an understanding of key features of upstream interaction and to identify physical and numerical issues relating to modeling of dual-mode configurations. The numerical analysis was performed with vitiated air at freestream Mach number of 2.5 using hydrogen as the sonic injectant. Results are presented for two-dimensional models and a three-dimensional jet-to-jet symmetric geometry. Comparisons are made with experimental results. Two-dimensional and three-dimensional results show …

Determination Of Life Cycle Cost Under Uncertainty, Hamoud R. Al-Otaibi

Mechanical & Aerospace Engineering Theses & Dissertations

The subject of this thesis is a Life Cycle Cost (LCC) model that takes into consideration the uncertainty of equipment failure rate and input data. The outcome of LCC depends on numerous estimates, forecasts, assumptions, and approximations of real-life data. Each of these factors has the potential to introduce error into the results. The study focuses upon the database generated for equipment failure rates data developed from historical database based on Weibull distribution parameters. The model provides a method to simulate real-world project life cycle.

2001 (Fall) Ensi Informer Magazine, Morehead State University. Engineering Sciences Department

ENSI Informer Magazine Archive

The ENSI Informer Magazine published in the fall of 2001.

Preliminary Evaluation Of Energy-Efficiency Improvements To Modular Classrooms, Florida Solar Energy Center, Danny Parker

FSEC Energy Research Center®

The objective of our investigation is to evaluate innovations that would enable modular classroom builders to improve the energy performance of their classrooms. We investigate improved insulation, better windows, daylighting, cross-ventilation, sensible and latent heat recovery of ventilation air and light colored surfaces and radiant barriers for cooling dominated climates. The tasks associated with this work are as follows:

• Create a simulation software.
• Establish a baseline reference building using a standard modular classroom building.
• Parametric evaluation of the impact of ventilation and school schedule on energy use.
• Determine the feasibility of improving insulation and envelope systems.
• Determine the feasibility of …

A Nonlinear Motion Cueing Algorithm With A Human Perception Model, Robert J. Telban

Link Foundation Modeling, Simulation and Training Fellowship Reports

The objective of a motion system, when used in conjunction with a visual system, is to stimulate the pilot so that he can perceive the required motion cues necessary to fly the simulator within the same performance and control activity as the aircraft. An example of a motion system is the six-degree-of-freedom hexapod shown in Figure E.l. Platform motion allows the pilot to react more quickly to simulated aircraft motion as compared to visual stimuli alone, thus enabling him to co1Tect (and reduce the magnitude) of any deviation sooner than having to wait for the information visually. Without motion cues …

Buckling Of Composite Conical Shells Under Combined Axial Compression, External Pressure, And Bending, Youngjin Chung

Dissertations

Conical shells are extensively used in space crafts, robots, shelters, domes, tanks, and in machinery or devices (e.g. as Belleville washers). Thus, the design of minimum weight, maximum strength, stiffened conical (and cylindrical) shells under combined loads has long been of interest to designers. The objective of this study is to improve the strength of conical shells and reduce the weight of the structure. Buckling of composite conical shells subjected to combined axial loading, external pressure, and bending is investigated using energy and finite element methods. The conical shells have single and multiple layers, different cone angle, length, and radius. …

Integration Of E-Business Strategy For Multi-Lifecycle Production Systems, Yanchun Luo

Dissertations

Internet use has grown exponentially on the last few years becoming a global communication and business resource. Internet-based business, or e-Business will truly affect every sector of the economy in ways that today we can only imagine. The manufacturing sector will be at the forefront of this change. This doctoral dissertation provides a scientific framework and a set of novel decision support tools for evaluating, modeling, and optimizing the overall performance of e-Business integrated multi-lifecycle production systems. The characteristics of this framework include environmental lifecycle study, environmental performance metrics, hyper-network model of integrated e-supply chain networks, fuzzy multi-objective optimization method, …

Dynamic Friction Of Uhmwpe Angular Compliant Bearing For Joint Implants And Machinery, Max Roman

Theses

The feasibility of a unique design of orthopedic- joint implant is investigated. The work focuses on the dynamic friction characteristics of a new joint. This unique design can be also useful in machinery involving oscillating motion similar to that of the hip joint during walking. An elastomeric layer bonded behind the rigid acetubular cup can be beneficial in improving the durability of prosthetic implants. Angular compliance offered by the elastomeric layer reduces relative sliding between the surfaces, lowers contact stresses by distributing pressure more evenly, and reduces the possibility of incongruent loading conditions caused by misalignment. The application of a …

Mechanical Design Of The Heater Used In Near Infrared Filter, Jun Ma

Theses

This thesis presents a design and analytical process in the application of the heater used in a near infrared filter working in Big Bear Solar Observatory, CA. The objective of the project is to achieve the physics parameters for the filter, which will be used in the observation of the solar activity.

The most important part of this design is to keep a relatively fixed temperature inside the oven-like heater. The reason is that optical properties of calcite (kind of filter in telescope) are pretty sensitive to a tiny disturbance on inside temperature. This was the biggest issue in this …

Evaluate Deployment Of Photovoltaic Systems For Disasters, Florida Solar Energy Center, William Young

FSEC Energy Research Center®

In 1996, the U.S. Department of Energy (DOE), developed a program with the Federal Emergency Management Agency (FEMA) to provide photovoltaic electrical power in disasters. In support of this effort, DOE purchased eight PV-generator trailers which were constructed in 1998 and supplied to FEMA for deployment in disaster response efforts. This report describes past and present use of the trailers, their depot location, list maintenance data, and the viability of the trailers in a disaster.

Disclination Loop Behavior Near The Nematic-Isotropic Transition, Nikolai V. Priezjev, Robert A. Pelcovits

Mechanical and Materials Engineering Faculty Publications

We investigate the behavior of disclination loops in the vicinity of the first-order nematic-isotropic transition in the Lebwohl-Lasher and related models. We find that two independent measures of the transition temperature, the free energy, and the distribution of disclination line segments, give essentially identical values. We also calculate the distribution function D(p) of disclination loops of perimeter p and fit it to a quasiexponential form. Below the transition, D(p) falls off exponentially, while in the neighborhood of the transition, it decays with a power-law exponent approximately equal to 2.5, consistent with a “blowout” of loops at the transition. In a …

Modeling, Fabrication, And Optimization Of Niobium Cavities – Phase I: Quarterly Progress Report May 15, 2001 - August 15, 2001, Robert A. Schill Jr., Mohamed Trabia

Transmutation Sciences Materials (TRP)

Multipacting is one of the major loss mechanisms in rf superconductivity cavities for accelerators. This loss mechanism limits the maximum amount of energy/power supported by the cavities. Optimal designs have been identified in others’ studies. In practice, these designs are not easily manufactured. Chemical etching processes used to polish the cavity walls result in a nonuniform surface etch compromising the optimal geometrical design. Past multipacting studies have not examined the impact of wall perturbations.

It is the purpose of this study to examine the chemical etching process in the design of niobium cavities so to maximize the surface quality of …

Ascent And Decompression Of Viscous Vesicular Magma In A Volcanic Conduit, Helene Massol, Claude Jaupart, Darrell Pepper

Mechanical Engineering Faculty Research

During eruption, lava domes and flows may become unstable and generate dangerous explosions. Fossil lava-filled eruption conduits and ancient lava flows are often characterized by complex internal variations of gas content. These observations indicate a need for accurate predictions of the distribution of gas content and bubble pressure in an eruption conduit. Bubbly magma behaves as a compressible viscous liquid involving three different pressures: those of the gas and magma phases, and that of the exterior. To solve for these three different pressures, one must account for expansion in all directions and hence for both horizontal and vertical velocity components. …

Photovoltaics In Disaster Management, Florida Solar Energy Center, William Young

FSEC Energy Research Center®

Man made or natural, disasters can happen at any time, often with little or no advance warning. Major disasters, such as hurricanes, floods, tornados, and earthquakes, can leave many people without adequate medical services, potable water, electrical service and communications. They can be as destructive as Hurricane Mitch leaving several hundred-thousand people homeless or as minor as an afternoon thunderstorm knocking down local power lines to your home.

In response to a disaster, photovoltaic (solar electric) modules offer a source of quiet, safe, pollution-free electrical power. Photovoltaic (PV) power systems are capable of providing the electrical needs for vaccine refrigerators, …

Empirical Modeling And Vision Based Control For Laser Aided Metal Deposition Process, Mallikharjuna R. Boddu, Srinivas Musti, Robert G. Landers, Sanjeev Agarwal, Frank W. Liou

Mechanical and Aerospace Engineering Faculty Research & Creative Works

This paper gives a brief description of the laser aided manufacturing process. Empirical models describing the process dynamics of the laser aided metal deposition process is developed based on some of the models found in the literature. These models provide the basis for process planning and real time control. An embedded vision system, a two color temperature sensor, and a laser displacement sensor are incorporated for real time monitoring and control of the deposition process. The temperature profile of the surface and geometric characteristics of the melt pool are studied to ensure consistent operation of the process.

Research And Development Of A Hybrid Rapid Manufacturing Process, Frank W. Liou, J. Choi, Robert G. Landers, Vijayakumar Janardhan, S. N. Balakrishnan, Sanjeev Agarwal

Mechanical and Aerospace Engineering Faculty Research & Creative Works

This paper presents the research and development of a hybrid rapid manufacturing process being developed at the University of Missouri--Rolla. This process includes a laser deposition and a 5- axis CNC milling system. By combining laser deposition and machining processes, the resulting hybrid process can provide greater build capability and better accuracy and surface finish. The hybrid process can build some features that are difficult to build in using a purely deposition processes. The issues and related approaches in the research and development of the hybrid deposition-machining process, including laser deposition process, system design and integration, process planning, and sensor …

Skeleton-Based Geometric Reasoning For Adaptive Slicing In A Five-Axis Laser Aided Manufacturing Process System, Kunnayut Eiamsa-Ard, Jun Zhang, Frank W. Liou

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Multi-axis Laser Aided Manufacturing Process (LAMP) is an additive manufacturing process similar to laser cladding. This process can produce full functional parts [1]. Traditional Layered Manufacturing processes produce parts with limited surface quality; and also the build time is often long due to the deposition of sacrificial support structure. The multiple degrees of freedom endow the LAMP system a capability to build parts without support structure. An algorithm for adaptive slicing based on skeleton is presented in this paper. The skeleton is useful for many applications such as feature recognition, robot path planning, shape analysis, and etc [2]. The near …

Control Of Laser Cladding For Rapid Prototyping -- A Review, Mallikharjuna R. Boddu, Robert G. Landers, Frank W. Liou

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Lasers have wide-ranging applications in the manufacturing field (e.g., cladding, welding, cutting, machining, drilling). Extensive work is being conducted to apply laser cladding as a Rapid Prototyping (RP) process. In this paper the authors illustrate various principles of laser cladding in rapid prototyping. Important process parameters for the control of the laser cladding process are discussed as well as the experimental methods adopted, and results obtained by, various authors.

A Comparative Study On Projected And Actual Manufacturing Times To Identify The Source Of Customer Delinquency, Zaki Kuruppalil

All-Inclusive List of Electronic Theses and Dissertations

This study was an investigation of the projected lead time and the actual lead time for a part manufactured at Tri-Industries Inc., Terre Haute, Indiana. The research was focused on a single part produced in Tri-Industries. The problem was that there is a difference in the projected lead time and the actual lead time of the part under investigation. The actual lead time was longer than projected lead time, which resulted in the company being delinquent in customer delivery. This investigation was conducted to find out the source for customer delinquency for a single part in Tri-Industries. The conclusion was …

Shock Layer Instability Near The Newtonian Limit Of Hypervelocity Flows, H. G. Hornung, P. Lemieux

Mechanical Engineering

The curved bow shock in hypersonic flow over a blunt body generates a shear layer with smoothly distributed vorticity. The vorticity magnitude is approximately proportional to the density ratio across the shock, which may be very large in hypervelocity flow, making the shear layer unstable. A computational study of the instability reveals that two distinct nonlinear growth mechanisms occur in such flows: First, the vortical structures formed in the layer move supersonically with respect to the flow beneath them and form shock waves that reflect from the body and reinforce the structures. Second, the structures deform the bow shock, forming …

Multidirectional Compliance And Constraint For Improved Robotic Deburring. Part 2: Improved Bracing, Joseph M. Schimmels

Mechanical Engineering Faculty Research and Publications

This two-part paper presents a method for both improving the positioning capability and increasing the effective stiffness (bracing) of a robotic manipulator through multidirectional compliance and constraint. Improved positioning and improved bracing are attained through the effective use of multiple unilateral kinematic constraints in different directions. The companion paper identified how to specify the compliant characteristics of a manipulator so contact forces lead to deflections that eliminate positional misalignments and result in improved relative positioning through force guidance. In this part, we show that the characteristics beneficial to force guidance are the same characteristics that provide improved bracing when partially …

Development Of An Integrated Sensor For The Measurement Of The Acoustic Local Volume Displacement Of Vibrating Beams, Randall Rozema

Masters Theses

Currently, the methods used for sensing the volume displacement of a vibrating structure entail the use of a polyvinylidene fluoride sensor that spans the entire length of the structure. However, this work shows that the surface behavior related to volume displacement can be measured through the use of a polyvinylidene fluoride sensor that spans only the area of interest. In this application it was shown that two-point sensors are required in addition to the distributed, polyvinylidene fluoride sensor to achieve an accurate measurement. As a result, a set of four beams with different end conditions were constructed so that the …