Engineering Commons^™

Input Design For Systems Under Identification Using Indirect And Direct Methods, Marco P. Schoen

Mechanical & Aerospace Engineering Theses & Dissertations

The motivation for system identification can be manifold. In this work, the provocation to identify unknown system characteristics is derived from the control engineering point of view. That is, one intends to design a control strategy based on the identified system properties. The used system identification methods are the Open-Loop Kalman filter System Identification method (OKID) and the Closed-Loop System Identification method (CLID). It is shown that the quantitative largest error of the system identification is given by its model representation, that is the attempt to describe a system with model parameters which poses a linear relationship with the input/output …

Balanced Dissipative Controllers For Flexible Structures, W. Gawronski, Jerzy T. Sawicki

Mechanical Engineering Faculty Publications

A balanced approach to shaping the closed-loop properties of the dissipative controllers for flexible structures is presented. In the balanced representation the properties of flexible structures are introduced, and a simple method of designing of the dissipative controllers is obtained. It relates the controller gains with the closed-loop pole locations. The examples illustrate the accuracy of the design method.

Tool Condition Monitoring: A Computational Approach, Anthony Clinch

Dissertations and Theses

Tool Condition Monitoring offers a new approach to reducing the costs associated with catastrophic tool failure. The manufacturing process is becoming more computationally oriented all the time. Computational methods of determining the condition of cutting tools will lend themselves to easy integration with current and forthcoming manufacturing techniques. Coupling the results of this computational approach with a cost analysis will provide a means of maximizing the investment in cutting tools, while minimizing the damage caused by tool failure. Tool Condition Monitoring, as defined here, is a method of computationally determining the condition of a cutting tool. The problem of determining …

Solar Hot Water Energy And Cost Savings For Typical Florida Residential Installations, Florida Solar Energy Center, David L. Block

FSEC Energy Research Center®

The following table presents energy and cost savings for four typical Florida solar water heating systems. Exact savings by a consumer may vary as much as plus or minus 25 from these numbers for numerous reasons. These include hot water usage, storage tank type, thermostat settings, solar system size, collector placement and local weather conditions. Computer simulations were used to generate the energy data.

Solar Heating Of Swimming Pools: A Question & Answer Primer, Florida Solar Energy Center, Charles Cromer

FSEC Energy Research Center®

Solar pool heating is one of the most economically attractive solar technologies in Florida today. If you are interested in heating your pool, or can no longer afford heating it with fossil fuel alone, consider installing a solar pool heater.

The following information helps answer the most frequently asked questions concerning solar pool heating in Florida. Keep in mind that much of this information is "rule of thumb"; your individual situation, if analyzed in detail, may differ somewhat from the general application. A more detailed analysis of pool systems is provided by the publications listed in the bibliography.

Analytical Solutions Of Openings Formed By Intersection Of A Cylindrical Shell And An Oblique Nozzle Under Internal Pressure, Hengming Cai

Dissertations

Since several decades ago, many authors have published their research results about local stress distributions of shells and shell-nozzles both analytically and numerically. However, there has not been a published paper, which deals with analytical solutions of cylindrical shell and oblique nozzle, even though in the case of openings formed by intersection of a cylindrical shell and an oblique nozzle.

A comprehensive analytical study of local stress factors at the area of openings formed by intersection of a cylindrical shell and an oblique nozzle under internal pressure is presented in this dissertation.

By means of traditional approach in theory of …

Shaped Charges Having A Porous Tungsten Liner-An Experimental And Theoretical Study Of Metal Compression, Jet Formation And Penetration Mechanics, Brian Edward Fuchs

Dissertations

The use of porous tungsten as a liner for shaped charges to improve their penetration was proposed by Ki-Hwan Oh in his invention disclosure "Shock Extrusion of Ingots from Powders or Solids", at the New Mexico Institute of Mining and Technology, Socorro NM on June 7, 1988. The intention was to increase the ductility of the normally brittle metal by heating the liner to a high temperature by shock compaction during its acceleration just before jet formation.

The feasibility of increasing the ductility of tungsten in this way is the subject of the present study. The theory and prior experimental …

Modeling Of Objects Using Planar Facets In Noisy Range Images, Girish Phansalkar

Theses

Products designed and manufactured before the advent of Computer Aided Design (CAD) and Computer Aided Manufacturing (CAM) technology have not been documented electronically. To avoid the laborious procedure of redesigning the parts, a reverse engineering approach can be adopted. This approach involves, taking a picture of the object and constructing a solid model from the image data.

Range image is a three dimensional image of an object or a scene. This image can be obtained from special cameras, called range image cameras, or can be constructed from the Coordinate Measuring Machine's (CMM) output data. Adaptive Fuzzy c-Elliptotype (AFC) clustering algorithm …

Experimental Study Of The Rise Of A Large Sphere In A Vibrated Bed Of Monodisperse Spheres, Loic Vanel

Theses

As a simplified way to study size segregation mechanisms, the rise of a single large sphere in a vibrated bed of smaller monodisperse spheres is investigated. The time it takes for the ball to rise from the bottom of the bed to the surface is measured in a very wide range of vibration amplitude, frequency and acceleration. Rise regimes are identified and are classified according to the macroscopic behaviors displayed by the granular bed: heaping, convection without heaping and crystallization. The influence of the large sphere's size on the rise velocity is described. The scaling features of the vibration amplitude …

Experimental Investigation Of Collisional Properties Of Spheres, Laurent Labous

Theses

We present experimental results on the collisional properties of spheres obtained through high-speed video analysis. An apparatus is built that produces collisions of spheres of various sizes with a wide range of impact, velocities and incidence angles.

Edge detection techniques are implemented to track the position of the spheres from frame to frame whereby the translational velocities may be computed. In order to determine the rotational velocities, small markers are imprinted on the surfaces of the spheres and also tracked and matched from one frame to the next.. From the pre and post collision kinematic data, three collisional properties are …

Tractor Test Museum Committee Minutes Jan 28, 1997, Tractor Museum

Lester F. Larsen Tractor Museum: Planning and Development Documents

Foundation Budget Recognition Certificates By-law changes

Evaluation Of Resources And Energy Systems At Fort Jefferson Garden Key, Dry Tortugas National Park, Florida Solar Energy Center, James Dunlop

FSEC Energy Research Center®

This report presents an evaluation of the resources and energy systems at Fort Jefferson, located on Garden Key in Dry Tortugas National Park, Florida. Conducted by Florida Solar Energy Center staff on June 11-12, 1997, this evaluation builds on a prior evaluation conducted in May 1989. The purpose of this evaluation was to document the energy and resource needs at the site, and to identify possibilities for reduced costs through conservation measures and renewable energy options.

Approximately 700 kWh of electrical energy is used at Fort Jefferson on a daily average, supplied exclusively by diesel-fueled generators. Average diesel fuel consumption …

The Role Of Computer Simulation In The Context Of Zero-Emission Power Plants, Jim Mcgovern

Other resources

The role of computer simulation in the context of zero-emission power plants is outlined. The use of computer simulation models to simulate zero-emission power plants in fine detail is strongly recommended.

Batteries And Charge Control In Stand-Alone Photovoltaic Systems: Fundamentals And Application, Florida Solar Energy Center, James Dunlop

FSEC Energy Research Center®

This report presents an overview of battery technology and charge control strategies commonly used in stand-alone photovoltaic (PV) systems. This work is a compilation of information from several sources, including PV system design manuals, research reports, data from component manufacturers, and lessons learned from hardware evaluations.

Withdrawal Strength Of Ring-Shank Nails Embedded In Southern Pine Lumber, M J. Skulteti, D A. Bender, S G. Winistorfer, David Pollock

Faculty Publications - Biomedical, Mechanical, and Civil Engineering

Ring-shank nails are used extensively in post-frame construction due to their superior performance, yet surprisingly little testing has been done on nail sizes above 12d. Experience in the post-frame industry suggests that published allowable design values for ring-shank nails may be overly conservative and need revision. The goal of the research reported herein was to characterize the withdrawal strength of ring-shank nails embedded in Southern Pine lumber. Three sizes ofgalvanized and ungalvanized (bright) ring-shank nails from two manufacturers were studied. Ring-shank nails had approximately twice the withdrawal resistance of smooth-shank nails of the same diameter. Galvanizing slightly reduced withdrawal strength …

Test 1726: John Deere 7710 Powrquad Diesel 16-Speed, Nebraska Tractor Test Lab

Nebraska Tractor Tests

EXPLANATION OF THE TEST PROCEDURE

General

Tractors are tested at the University of Nebraska according to the Agricultural Tractor Test Code approved by the American Society of Agricultural Engineers and the Society of Automotive Engineers or official Nebraska test procedure.

The manufacturer selects the tractor to be tested and certifies that it is a stock model. Each tractor is equipped with the common power consuming accessories such as power steering, power lift pump, generator, etc., if available. Power consuming accessories may be disconnected only when the means for disconnecting can be reached from the operating station. An official representative of …

Two-Phase Flow In Microchannels, Roger Scott Stanley

Doctoral Dissertations

The purpose of this study was to investigate fluid mechanic and heat transfer characteristics of two-phase two-component flow in rectangular microchannels. Experiments were conducted using rectangular aluminum channels with hydraulic diameters ranging between 56 $\mu$m and 256 $\mu$m and aspect ratios which varied from 0.5 to 1.5. Both single- and two-phase tests were conducted using water and gaseous argon, helium, and nitrogen as the working fluids. The Reynolds number for both types of experiments ranged from approximately 50 to nearly 10,000. The Nusselt number ranged between 0.0002 and 70. The single- and two-phase experimental data were empirically correlated, using parameters …

A Cell Model For Ductile Fracture With Applications, C. Fong Shih, Li Cheng, J. Faleskog, Xiaosheng Gao

Mechanical Engineering Faculty Research

No abstract provided.

Diophantine Type Fractional Derivative Representation Of Structural Hysteresis, Part Ii: Fitting, Computational Mechanics, Jerzy T. Sawicki, Joe Padovan

Mechanical Engineering Faculty Publications

Part I of this series introduced the diophantinized fractional model and the decompositional formulation. The various important properties of fractional continuum formulation and its decomposed version were developed. In Part II the dynamic properties of the diophantine representation are investigated. The model fitting scheme will be developed to handle an arbitrary frequency dependent structural hysteriesis. This is followed up with the results of benchmark studies which demonstrate the effectiveness of fitting.

The Effects Of Machining On Structure And Tribological Properties Of Ultra High Molecular Weight Polyethylene For Artificial Joint Prostheses, Jinshan Song

Masters Theses

Understanding the effect of machining on the structure and property of subsurface layer of ultra high molecular weight polyethylene (UHMWPE) can significantly facilitate the increase in longevity of artificial joints. This study was performed to investigate the machining effects on the polymeric structure and tribological properties. Machining parameters include cutting speed, tool feed rate and depth of cut. Temperature rise was studied during machining to assess the extent of thermal degradation due to machining. Polymeric structure of the semicrystalline polymer was characterized using differential scanning calorimetry (DSC) in terms of melting enthalpy, crystallinity and melting temperature. Surface texture and hardness …

Nebraska Summary 280: Massey Ferguson 4370 And 4270 Diesel 12-Speed, Nebraska Tractor Test Lab

Nebraska Tractor Tests

ABOUT THE TEST REPORT AND USE OF THE DATA

The test data contained in this report are a tabulation of the results of a series of tests. Due to the restricted format of these pages, only a limited amount of data and not all of the tractor specifications are included. The full OECD report contains usually about 30 pages of data and specifications. The test data were obtained for each tractor under similar conditions and therefore, provide a means of comparison of performance based on a limited set of reported data.

EXPLANATION OF THE TEST PROCEDURES

Purpose

The purpose of …

Chemical Stability Study Of Bace0.9Nd0.1O3−Α High Temperature Proton-Conducting Ceramic, Fanglin Chen, O. Toft Sorensen, Guangyao Meng, Dingkum Peng

Faculty Publications

BaCe_0.9Nd_0.1O_3−a (BCN) ceramic is known to be an excellent high-temperature proton conductor and is a candidate electrolyte for use in solid oxide fuel cells, hydrogen or steam sensors and steam electrolysers. In this work, the chemical stability of BCN was investigated systematically by combining XRD and DTA–TG techniques to study its processing compatibility and its feasibility in potential applications. It was found that above 1200 °C, BCN reacted with alumina or zirconia, leading to the loss of barium and an excess of cerium. In cold water, both sintered BCN disks and powder samples had very …

Nebraska Summary: S252 New Holland 8360, Nebraska Tractor Test Lab

Nebraska Tractor Tests

ABOUT THE TEST REPORT AND USE OF THE DATA The test data contained in this report are a tabulation of the results of a series of tests. Due to the restricted format of these pages, only a limited amount of data and not all of the tractor specifications are included. The full OECD report contains usually about 30 pages of data and specifications. The test data were obtained for each tractor under similar conditions and therefore, provide a means of comparison of performance based on a limited set of reported data. EXPLANATION OF THE TEST PROCEDURES Purpose The purpose of …

Nebraska Summary: S244 New Holland 4835, Nebraska Tractor Test Lab

Nebraska Tractor Tests

ABOUT THE TEST REPORT AND USE OF THE DATA The test data contained in this report are a tabulation of the results of a series of tests. Due to the restricted format of these pages, only a limited amount of data and not all of the tractor specifications are included. The full OECD report contains usually about 30 pages of data and specifications. The test data were obtained for each tractor under similar conditions and therefore, provide a means of comparison of performance based on a limited set of reported data. EXPLANATION OF THE TEST PROCEDURES Purpose The purpose of …

Test 1743: Belarus 9345, 9011, 9045 And 9311 Diesel 14-Speed, Nebraska Tractor Test Lab

Nebraska Tractor Tests

EXPLANATION OF THE TEST PROCEDURE

General

Tractors are tested at the University of Nebraska according to the Agricultural Tractor Test Code approved by the American Society of Agricultural Engineers and the Society of Automotive Engineers or official Nebraska test procedure.

The manufacturer selects the tractor to be tested and certifies that it is a stock model. Each tractor is equipped with the common power consuming accessories such as power steering, power lift pump, generator, etc., if available. Power consuming accessories may be disconnected only when the means for disconnecting can be reached from the operating station. An official representative of …

Bridge Engineering For The Elementary Grades, Douglas R. Carroll

Mechanical and Aerospace Engineering Faculty Research & Creative Works

A one-hour presentation was developed to get elementary school students interested in engineering. The presentation begins with the students building six feet long, structurally sound bridge which they can crawl across. A pictorial presentation helps them learn to identify some of the different types of bridges: truss, stone arch, steel arch, concrete girder, cable-stayed, and suspension. They are introduced to the fundamental engineering concepts of tension and compression. These concepts are reinforced by demonstrating that if a tension member is replaced with a chain then the bridge is still strong, but if a compression member is replaced with a chain …

Extracting The Grain Boundary Character/Free Energy Relationship From The Microstructure: Pure <100> And <111> Tilt Boundaries, Brent L. Adams, S. Costiner, D. Kinderlehrer, W. W. Mullins, Shlomo Ta'asan

Faculty Publications

This work was supported primarily by the MRSEC Program of the National Science Foundation under Award Number DMR-9632556. Analysis is described to extract the excess free energy of grain boundaries from the mesotexture of well-equilibrated polycrystalline samples. The approach is based upon the force and torque balances at triple junctions described in the classical work of Herring. The main advantage of the approach is that the free energy function is obtained over the full fundamental zone of grain boundary types. For the purposes of exposition, the method is described for specified two-parameter hypersurfaces in the fundamental zone for cubic polycrystals …

A Finite Element Formulation For Aft Fan Duct Acoustic Radiation, Walter Eversman

Mechanical and Aerospace Engineering Faculty Research & Creative Works

A finite element code has been developed for the prediction of the radiated acoustic field in and around the aft fan duct of a turbofan engine. The acoustic field is modeled based on the assumption that the steady flow in and around the nacelle is irrotational as is the acoustic perturbation. The geometry of the nacelle is axisymmetric, and the acoustic source is harmonic and decomposed into its angular harmonics. The steady flow is computed on the acoustic mesh and provides data for the acoustic calculations. The jet is included in the steady flow potential flow model by separating the …

Integrating Design Into The Sophomore And Junior Level Mechanics Courses, Douglas R. Carroll

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Engineering schools across the country are developing ways of integrating design into their curriculum, and a question that often arises is how to best integrate design into the sophomore and junior level courses. Freshman design projects or mechanical dissection courses are designed to give the students hands-on experience in conceptual design and construction, with little if any of the mathematical modeling normally used in engineering design. The capstone senior design project is a true engineering design experience, where students draw from their background to conceptualize, analyze, model, refine, and optimize a product to meet design, manufacturing, and life cycle cost …

Tests 1684 & 1730: Zetor 7341 Super/Zetor 7321 Super Diesel, Nebraska Tractor Test Lab

Nebraska Tractor Tests

No abstract provided.