Engineering Commons^™

Simulation Of Engineering Systems Described By High-Index Dae And Discontinuous Ode Using Single Step Methods, Marc Compere

Publications

This dissertation presents numerical methods for solving two classes of or-dinary diferential equations (ODE) based on single-step integration meth-ods. The first class of equations addressed describes the mechanical dynamics of constrained multibody systems. These equations are ordinary differential equations (ODE) subject to algebraic constraints. Accordinly they are called differential-algebraic equations (DAE).

Specific contributions made in this area include an explicit transforma-tion between the Hessenberg index-3 form for constrained mechanical systems to a canonical state-space form used in the nonlinear control communities. A hybrid solution method was developed that incorporates both sliding-mode control (SMC) from the controls literature and post-stabilization from …

Spline Based Path Planning For Unmanned Air Vehicles, Kevin B. Judd, Timothy W. Mclain

Faculty Publications

A trajectory planning scheme that generates feasible flight routes for an unmanned air vehicle (UAV) is developed. A preliminary path is generated from a Voronoi diagram based on threat locations. This path consists of a series of straight-line segments that cannot be followed exactly by the UAV. Using a series of cubic splines to connect these straight-line segments, this path is refined into an optimum path that is flyable by the UAV. Utilizing a decomposition strategy, both the full path (coarse detail) to the target and the proximate optimum path (fine detail) near the UAV can be quickly computed. The …

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 …

Delamination Resistant Composites Prepared By Small Diameter Fiber Reinforcement At Ply Interfaces, Youris A. Dzenis, Darrell H. Reneker

Department of Mechanical and Materials Engineering: Faculty Publications

A fiber reinforced composite material comprising a resin matrix and primary reinforcement fibers and further comprising secondary, smaller diameter, reinforcement fibers at one or more ply interfaces, or portion thereof, provides improved interlaminar toughness, strength, and delamination resistance and without substantial increase in weight. In one embodiment, the small fibers are attached to one side of a conventional prepreg prior to lamination. The small fibers are flexible and are expected to conform to the shape and distribution of the primary reinforcing fibers at the interface.

Jul 2001, Tractor Museum

Lester F. Larsen Tractor Museum: Planning and Development Documents

UN Foundation Tractor Raffle Oliver Tractor Repair

Modal Uncoupling Of Damped Gyroscopic Systems, Jerzy T. Sawicki, G. Genta

Mechanical Engineering Faculty Publications

A new approach for uncoupling the equations of motion typical for rotordynamical systems is presented. The method does not neglect the speed-dependent e!ects, such as gyroscopic e!ects, and can be particularly valuable in the controller design of actively controlled rotors. In the presence of hysteretic type of damping, the resulting uncoupled gyroscopic systems come with an equivalent viscous damping, equivalent in a sense of yielding the same natural frequency and decay rate. The approach is illustrated through three examples of technical interest: a Je!cott rotor with hysteretic damping, a Stodola}Green rotor, and a rotor of a small gas turbine. The …

Energy Absorbing Breakaway Steel Guardrail Post, John R. Rohde, John D. Reid, Dean L. Sicking

Department of Mechanical and Materials Engineering: Faculty Publications

An improved breakaway steel guardrail post for use in dissipation of impact energy upon impact of the post having an upper post member and a lower post member, a connecting joint, and a mechanism connected to the upper and lower post members for controlling the energy dissipation of the guardrail post about the connecting joint at a predetermined rate. A first embodiment utilizes a cable restraint lopped through openings in he guardrail posts. Other embodiments included straps and fasteners disigned to distort or fail at predetermined rates or strengths and combinations thereof.

Fuel-Saving Strategies For Dual Spacecraft Interferometry Missions, Christopher A. Bailey, Timothy W. Mclain, Randal W. Beard

Faculty Publications

Separated spacecraft interferometry missions will require that spacecraft move in a coordinated fashion to ensure minimal and balanced consumption of fuel. This paper develops strategies for determining interferometry mission plans that result in significant fuel savings over standard approaches. Simulation results demonstrate that valuable reductions in fuel consumption can be realized by combining the retargeting and imaging maneuvers required to image multiple stellar sources. Fuel-optimal imaging strategies have been developed for two-spacecraft interferometry missions similar to the proposed StarLight mission using chained local optimization methods. Based on these strategies, sampling-pattern guidelines for space-borne interferometry missions have been developed.

Ingaasnsb/Gaas Quantum Wells For 1.55 Μm Lasers Grown By Molecular-Beam Epitaxy, Xiaodong Yang, J. B. Heroux, L. F. Mei, W. I. Wang

Mechanical and Aerospace Engineering Faculty Research & Creative Works

InGaAsNSb/GaAs quantum wells (QWs) were grown by solid-source molecular-beam epitaxy using a N₂ radio frequency plasma source. The effect of adding Sb during growth of InGaAsN/GaAs QWs was studied. X-ray diffraction, reflection high-energy electron diffraction and transmission electron microscopy studies indicate that Sb suppresses the three-dimensional growth and improves the interface of the QWs. X-ray diffraction and secondary ion mass spectroscopy analysis show that Sb gets incorporated into the quantum well, which becomes a quinternary compound that was previously unexplored. The introduction of Sb during growth of InGaAsN/GaAs QWs significantly enhances the optical properties of the QWs. 1.53 /spl …

Computer-Aided Engineering For Tool Design In Manufacturing Engineering Curriculum, Daniel J. Waldorf

Industrial and Manufacturing Engineering

At Cal Poly – San Luis Obispo, a variety of tool design issues are covered in a junior-level manufacturing engineering course called Tool Engineering. In the course, designing fixtures – for any process – is a major component of the content. The process of designing a fixture is similar to the method a mechanical engineer would use to design a new product. The course is therefore an excellent opportunity to teach design principles to manufacturing engineers. This project involves an attempt to introduce computer-aided methods, including the finite element method (FEM), for analysis of tool design into the Tool Engineering …

Solar Cooker Reflector Optical Evaluation And Design Evolution, Florida Solar Energy Center, Ross Mccluney

FSEC Energy Research Center®

Solar Cooker Reflector Optical Evaluation and Design Evolution

A Numerical Model For The Cyclic Instability Of Thermally Grown Oxides In Thermal Barrier Systems, Anette M. Karlsson, A. G. Evans

Mechanical Engineering Faculty Publications

Morphological instability of the thermally grown oxide (TGO) is a fundamental source of failure in some thermal barrier systems. The instabilities occur when initial non-planarity in the TGO grows in amplitude as the system experiences thermal cycling. By numerical means, this study explores how these instabilities are linked to constituent properties. The associated phenomena involve oxidation of the TGO, plastic flow of the bond coat, thermal expansion misfit between the TGO, bond coat and substrate, and stress relaxation in the TGO at high temperature. A key implication of the simulations is that the incidence of reverse yielding upon reheating differentiates …

Controlled Buckling Breakaway Cable Terminal, John D. Reid, John R. Rohde, Dean L. Sicking

Department of Mechanical and Materials Engineering: Faculty Publications

A crash attenuation apparatus for use with a guardrail system having rail posts and rail elements. An impact head has a buffer nose section and a rail post breaking beam system. The post breaking beam system has upper and lower breaking beams attached to the head. A guide tube is attached to the side of the head. A strut member extends from a first attachment point on the rail element to a second point downstream. Upon impact by a vehicle, the head breaks the first rail post, before impacting the strut and buckling the rail element downstream.

Increasing Power Density Of Lsgm-Based Solid Oxide Fuel Cells Using New Anode Materials, Kevin Huang, Jen-Hau Wan, John B. Goodenough

Faculty Publications

Chemical reactions between the superior perovskite oxide-ion conductor Sr- and Mg-doped LaGaO₃ (LSGM), CeO₂, and NiO have been studied by powder X-ray diffraction. The results showed that an extensive reactivity occurs as a result of La migration driven by a gradient of La chemical activity. La migration across the LSGM/electrode interfaces in a fuel cell leads to the formation of resistive phases at the interface, either LaSrGa₃O₇ or LaSrGaO₄. Use of 40 mol % La₂O₃ -doped CeO₂ as an interlayer between anode and electrolyte as well as in …

Developing An Implementation Plan For The Arkansas Msri Coalition Workshop Summary - Final Report, Florida Solar Energy Center, Jennifer Szaro

FSEC Energy Research Center®

Workshop conducted to develop an implementation plan for the Arkansas Million Solar Roofs Initiative.

Developing An Implementation Plan For The Alaskan Msri Coalition Workshop Summary - Final Report, Florida Solar Energy Center, Gerard Ventre

FSEC Energy Research Center®

Workshop conducted to develop and implementation plan for the Alaskan Million Solar Roofs Initiative.

Teaching Factory, Sema E. Alptekin, Reza Pouraghabagher, Patricia Mcquaid, Daniel Waldorf

Industrial and Manufacturing Engineering

Academia must develop a new approach to teaching in order to better prepare engineering students to function efficiently and adjust readily within the framework of the factories in the real world. Some engineering programs emphasize theory, while others emphasize application as isolated blocks. The "Teaching Factory" being developed at Cal Poly combines both theory and applications. It makes use of state-of-the-art industrial grade production equipment, computer hardware and software in the form of the following two systems: 1) a functioning "real" factory hardware environment, and 2) a Production Planning and Control Center.

Typical Photovoltaic System For A Commercial Building, Florida Solar Energy Center, Gobind Atmaram

FSEC Energy Research Center®

This paper covers the design and installation of an 11 peak kilowatt (kWp) grid-connected photovoltaic system on the roof of the new facilities at the Florida Solar Energy Center (FSEC7). The main objectives of this work are to demonstrate the application of photovoltaics (PV) as a demand-side management option for meeting peak commercial electric loads and provide a typical PV array and system design for commercial buildings. The PV array consists of 48 ASE America=s EFG ribbon silicon modules and is interfaced with three Omnion 4kW power conditioners. The complete array and system electrical design and installation were performed by …

Cooperative Control Of Uav Rendezvous, Timothy W. Mclain, Phillip R. Chandler, Steven Rasmussen, Meir Pachter

Faculty Publications

The cooperative control of timing and synchronization of tasks of multiple unmanned air vehicles (UAVs) represents a valuable capability for a wide range of potential multi-UAV missions. This research addresses the specific problem of cooperative rendezvous in which multiple UAVs are to arrive at their targets simultaneously. The development of a rendezvous manager state machine and a cooperative control decomposition approach are described. Simulation results demonstrating the feasibility of the approach are presented.

Determination Of Statistical Characteristics Of Isotropic Turbulence, Tatiana A. Andreeva, William W. Durgin, F. J. Weber, Hamid Johari

Office of the Provost Scholarship

Ultrasonic flow measurement technology has the potential to significantly improve flow measurement accuracy beyond that presently achieved. However, current applications fail to achieve theoretical accuracies because of turbulence effects on ultrasonic wave transit time. Herein, the ultrasonic flowmeter equation is reconsidered, where the effects of turbulent velocity and sound speed fluctuations are included. The result is an integral equation for the corresponding correlation functions. In this paper experimental velocity data are used to solve this integral equation analytically. As a result, some statistical characteristics of the turbulent flow are developed and can explain the limitations of measurement accuracy observed in …

Ultrasonic Beam Propagation In Turbulent Flow, William W. Durgin, F. J. Weber, Hamid Johari

Office of the Provost Scholarship

A study was conducted to examine how a coherent sound burst, such as those used in an ultrasonic flowmeter, crosses a turbulent flow field. Many ultrasonic flowmeters use a time of flight method to determine the mean flow. This measurement method sends sound waves at some angle across a velocity field between two transducers, and the time required for the sound burst to cross this distance is measured on the order of nanoseconds. The system then reverses so that the sound wave burst is sent in the opposite direction. Knowing the distance traveled, the local average sound speed, and the …

Fsec Procedure For Testing Stand-Alone Photovoltaic Systems, Florida Solar Energy Center

FSEC Energy Research Center®

This procedure is based on IEEE P1526/D1, Draft Recommended Practice for Testing the Performance of Stand-Alone Photovoltaic Systems. The system performance is based upon how well it can charge the battery. The usable battery capacity is measured by charging and discharging the battery three separate times. The tests are designed to test the overall system performance in the span of about one month.

Cluster Monte Carlo Simulations Of The Nematic--Isotropic Transition, Nikolai V. Priezjev, Robert A. Pelcovits

Mechanical and Materials Engineering Faculty Publications

We report the results of simulations of the three-dimensional Lebwohl-Lasher model of the nematic-isotropic transition using a single cluster Monte Carlo algorithm. The algorithm, first introduced by Kunz and Zumbach to study two-dimensional nematics, is a modification of the Wolff algorithm for spin systems, and greatly reduces critical slowing down. We calculate the free energy in the neighborhood of the transition for systems up to linear size 70. We find a double well structure with a barrier that grows with increasing system size. We thus obtain an upper estimate of the value of the transition temperature in the thermodynamic limit.

Membrane Electrostatic Precipitator, Hajrudin Pasic, M. Khairul Alam, David J. Bayless

Mechanical and Aerospace Engineering Faculty Research & Creative Works

A membrane is used as a collection substrate in an electrostatic precipitator (ESP). Possible material choices include fibers in the form of woven mats, screens made from stainless steel wires or fiber reinforced polymer composite membranes. The membranes have a tensile bias applied during operation, and have impulse tensile force applied during a dust removal step. By combining a dry ESP membrane field with wet-film cleaning field, it may be possible to improve collection efficiencies both by reducing turbulence and eliminating re-entrainment losses due to rapping. Through implementation of new materials that resist hostile ESP environments, the invention enhances the …

Comparison Of Two Distributed Fuzzy Logic Controllers For Flexible-Link Manipulators, Linda Z. Shi, Mohamed Trabia

Mechanical Engineering Faculty Presentations

The paper suggests that fuzzy logic controllers present a computationally efficient and robust alternative to conventional controllers. The paper presents two possible structures for the distributed fuzzy logic controller of a single-link flexible manipulator. A linear quadratic regulator method is used to prove the effectiveness of fuzzy logic controllers.

Design Of Fuzzy Logic Controllers For Optimal Performance, Mohamed Trabia

Mechanical Engineering Faculty Presentations

While fuzzy logic controllers are generally robust, the performance of a system whose behavior is not well understood, or that has a large number of coupled inputs and outputs, may be less than optimal. In this paper, nonlinear programming techniques are used to improve the performance of a fuzzy logic controller for navigating an autonomous vehicle.

Overview Of Fuzzy Logic, Mohamed Trabia

Mechanical Engineering Faculty Presentations

The presentation includes a brief introduction to fuzzy logic and fuzzy logic controllers. These concepts are illustrated by an example of an autonomous vehicle controller.

Oxygen Permeation Through Cobalt-Containing Perovskites: Surface Oxygen Exchange Vs. Lattice Oxygen Diffusion, Kevin Huang, John B. Goodenough

Faculty Publications

The oxygen permeation fluxes from p′_O2 to pⁿ_O2 (p′_O2>pⁿ_O2) across cobalt-containing perovskite ceramic membranes La_1−xSr_xCoO_3−δ and SrCo_0.8Fe_0.2O_3−δ were measured by gas chromatography as functions of oxygen chemical potential gradient, temperature, thickness, and catalytic activity on the surface. Power indexes 0.5>n>0 for uncatalyzed La_1−xSr_xCoO_3−δ and 1>n>0.5 for SrCo_0.8Fe_0.2O_3−δ were obtained when J_O2 vs. p′ⁿ_O2−p'′ⁿ_{O2 …}

A New Portable, Pc Based, Usb Powered Dynamic Signal Analyzer, Charles Birdsong, George Ma, James Nieters, Justin Tang, Caine Yu

Mechanical Engineering

A new USB powered portable 4-channel real time Dynamic Signal Analyzer and its automotive applications are described. The design and architecture lend themselves to real time NVH measurements and analysis in the field, in-vehicle or on production lines. Built-in signal conditioning provides for direct sensor power while the embedded DSP provides for signal processing on-board. Performance and implementation of FFT, digital filters and order analyses are presented.

An Electronically Tunable Resonator For Noise Control, Charles Birdsong, Clark J. Radcliffe

Mechanical Engineering

Many engineering systems create unwanted noise that can be reduced by the careful application of engineering noise controls. When this noise travels down tubes and pipes, a tuned resonator can be used to muffle noise escaping from the tube. The classical examples are automobile exhaust and ventilation system noise. In these cases where a narrow frequency band of noise exists, a traditional engineering control consists of adding a tuned Helmholtz resonator to reduce unwanted tonal noise by reflecting it back to the source (Temkin, 1981). As long as the frequency of the unwanted noise falls within the tuned resonator frequency …