Engineering Commons^™

Calculations Of The Interactions Of Energetic Ions With Materials For Protection Of Computer Memory And Biological Systems, Myung-Hee Y. Kim

Dissertations, Theses, and Masters Projects

Theoretical calculations were performed for the propagation and interactions of particles having high atomic numbers and energy through diverse shield materials including polymeric materials and epoxy-bound lunar regolith by using transport codes for laboratory ion beams and the cosmic ray spectrum. Heavy ions fragment and lose energy upon interactions with shielding materials of specified elemental composition, density, and thickness. A fragmenting heavy iron ion produces hundreds of isotopes during nuclear reactions, which are treated in the solution of the transport problem used here. A reduced set of 80 isotopes is sufficient to represent the charge distribution, but a minimum of …

Resuspension Behavior Of Natural Estuarine Sediments, Chang-Hee Lee

Dissertations, Theses, and Masters Projects

The resuspension behavior of natural estuarine sediments was studied using the VIMS Sea Carousel, a benthic annular flume. The bed shear stresses produced by the flume were measured by a hot-film sensor mounted flush on the bottom of a laboratory version of the Carousel under a clear-water and flat-bottom condition. Measurements showed a reasonably uniform bed shear stress across the channel and agreed with the relationship &\tau\sb{lcub}\rm b{rcub}=0.011\Omega\sp{lcub}1.69{rcub},& where &\Omega& = ring speed (rpm) and &\tau\sb{lcub}\rm b{rcub}& = spatially-averaged bed shear stress (N/m&\sp2&), predicted from a previous numerical study. Thus, the &\tau\sb{lcub}\rm b{rcub}& was used as a bed shear stress …

Metallization Of Polyimide Films To Enhance Dimensional Stability And To Achieve Reflective And Conductive Surfaces, David Scott Thompson

Dissertations, Theses, and Masters Projects

No abstract provided.

Characterization Of Nylon-11 Degradation, Leslie Christian Mccullough

Dissertations, Theses, and Masters Projects

No abstract provided.

Characterization Of Pr500 For Use In Resin Transfer Molding, Rhonda Michelle Barksdale

Dissertations, Theses, and Masters Projects

No abstract provided.

Effect Of Agricultural Fiber Reinforcement On The Mechanical Properties Of A Recycled Polyethylene Plastic Composite Material, Michael E. Courbat

Dissertations and Theses @ UNI

This study determined the effect of certain agricultural fiber reinforcements on the tensile and impact mechanical properties of a recycled polyethylene plastic composite material. The purpose of the study was to provide information on certain mechanical properties of a recycled polyethylene plastic material as part of a coordinated materials application process.

A prototype product run of the plastic composite material was done and test specimens were selected from this material. Notch impact, tensile, and flexure tests were conducted on test specimens. Test procedures complied with accepted standards from The American Society For Testing and Materials (ASTM). Tests were conducted on …

An Analysis Of The Use Of Programmable Controllers To Control An In Situ Leach Mine Wellfield, Jimmy W. Stokey

Dissertations and Theses @ UNI

In situ mining is a relatively new method that has the potential of recovering a variety of minerals. This process is quickly becoming an alternative to conventional mining techniques that are environmentally unsound. Two problems associated with in situ mining are, the amount of waste water generated by the process (bleed) and the uncontrolled migration of lixiviant outside the production zone (an excursion).

The purpose of this study was to determine if in situ mining processes could be monitored and controlled with a Sequential Control and Data Acquisition (SCADA) system. Using programmable logic controllers, a cost-effective SCADA system was designed …

Hardware Implementation Of The Complex Hopfield Neural Network, Chih Kang Cheng

Theses Digitization Project

No abstract provided.

Convergence Properties Of Perceptrons, Ratnasri Krishna Adharapurapu

Theses Digitization Project

No abstract provided.

A Comparative Study Of The Perceived Educational Needs Of Iowa Merged Area Vii Manufacturers And Iowa Technical Educators, David D. Bradney

Dissertations and Theses @ UNI

This research was a descriptive pilot study that compared the perceptions of Iowa Merged Area VII manufacturers and Iowa technical educators regarding technical curricula, occupational skill certification, and drafting practices as these relate to Associate Degree programs in Mechanical Drafting and Design Technology. The problem was to determine what should be taught in two year technical curricula in Mechanical Drafting and Design Technology. The purpose of the study was to compare the perceived educational needs of Iowa Merged Area VII manufacturers and Iowa technical educators regarding the content of Mechanical Drafting and Design Technology curricula. The populations used for this …

A Neural Network Thrust Force Controller To Minimize Delamination During Drilling In Graphite Epoxy Laminates, Robert B. Stone

Masters Theses

"Delamination is a well-recognized problem associated with drilling in fiber-reinforced composite materials (FRCM). The most noted problems occur as the drill enters and exits the FRCM. Since drilling is often a final operation during assembly, any defects introduced in parts by drilling represent an expensive loss. Studies based on linear elastic fracture mechanics theory have proposed critical thrust forces in the various drilling regions that will prevent crack growth or delamination. Using these critical thrust force curves as a guide, a thrust force controller was developed to minimize the delamination while drilling in graphite epoxy laminates. A neural network control …

Gaussian Beam Resonator Formalism Using The Yy Method, Kenneth A. Menard

Retrospective Theses and Dissertations

A simple and powerful new paraxial ray formalism is shown to provide an alternate method for designing Gaussian Beam Resonators. The theory utilizes the Delano yybar diagram approach and is an extension of the recent work by Shack and Kessler for laser systems. The method is shown to be complementary to the conventional ABCD method and is founded upon J.A. Arnaud's pioneering ideas for complex rays. The thesis develops an analytic formulation of a ray based complex wavefront curvature and yields a clearly generalized description of spherical wave propagation, for which Gaussian beams are considered a special case. The resultant …

Development Of A Desuperheater Rating Method For Energy Code Calculations, Tim Merrigan

Retrospective Theses and Dissertations

The purpose of this project was to develop a rating method for desuperheater water heaters – heat exchangers that remove superheat from the refrigerant in an air conditioner’s compressor discharge line. The project methodology was to first determine the overall heat transfer coefficient-area product (UA) of the heat exchanger for three basic types of desuperheaters. Both heat transfer analysis and the laboratory performance data indicated that the number of transfer units (NTU) for each heat exchanger was relatively independent of the operating conditions for a properly-charged air conditioner with a single-speed compressor and a desuperheater with a single-speed circulating pump. …

A General Method For The Inverse Kinematics Of Rotational Displacements In Spatial Mechanisms, John D. Kliminski

Theses

An iterative technique was developed to solve the inverse kinematics problem for the joint rotations in both closed-loop and open-loop spatial mechanisms and robotic manipulators in any prescribed configuration. The method is based on fixing one link in space and maneuvering the other links to form a closed chain, following an approximation of the actual physical assembly of the mechanism. In order to apply the same principle to both types of mechanisms, an open-loop mechanism was modeled as a closed-loop mechanism by creating a fictitious fixed link in the free space between the base and the end of the chain …

An Investigation Into Artificial Intelligence Based Generative Computer Process Planning, William Tereshkovich

Theses

The process planning function can be further optimized with the introduction of an intelligent software package such as an Artificial Intelligence based Generative Computer Process Planning System. An AI based CAPP system, also categorized as an expert system, provides the vital link between design and manufacture, a "bridge" of knowledge in the information chain of manufacturing engineering. With the increasing role of computers in the process planning function, planning has become easier, faster, and more efficient.

This thesis provides an explanation of the process planning function and how artificial intelligence will improve it. Topics in AI techniques and procedures, knowledge …

A Silicon Knife Design And Fabrication, Mingli Wang

Theses

In this thesis, the design and fabrication of a silicon knife is described. The device design is based on the principle of oxidation sharpening.

The knife is made from a silicon wafer and can be made to be any chosen length up to 150 mm. It was made with the same basic procedures used in semiconductor chip manufacturing. This type of processing/manufacturing results in a knife with a high degree of sharpness and smoothness compared with existing knife technology.

The knife fabrication plan combines IC processing, techniques including anisotropic and isotropic etching of silicon, plasma dry etching and chemical etching …

Video Coding For Bit Rates 64kbps And Below, Geoffrey N. Alagoda

Theses : Honours

With digital motion video for either transmission or storage, there always exists a trade-off between the data transmission rate and the picture quality. The lower the transmission bit-rate is made, the more the quality of the image tends to degrade. With usual transform coding schemes the degradation usually occurs when low bit-rates, that is less than about 64Kbps, are used. The resultant image tends to suffer visually from a ''blocking" effect. This thesis therefore, is based on the development of a different implementation scheme, for motion video compression or encoding, so as to support both low bit-rates, around 64Kbps or …

Hardware For Fast Global Operations On Distributed Memory Multicomputers And Multiprocessors, Douglas V. Hall

Dissertations and Theses

"Grand Challenge" problems such as climate modeling to predict droughts and human genome mapping to predict and possibly cure diseases such as cancer require massive computing power. Three kinds of computer systems currently used in attempts to solve these problems are "Big Iron" multicomputers such as the Intel Paragon, workstation cluster multicomputers, and distributed shared memory multiprocessors such as the Cray T3D. Machines such as these are inefficient in executing some or all of a set of global program operations which are important in many of the "Grand Challenge" programs. These operations include synchronization, reduction, MAX, MIN, one-to-all broadcasting, all-to-all …

Beam Modes Of Lasers With Misaligned Complex Optical Elements, Anthony A. Tovar

Dissertations and Theses

A recurring theme in my research is that mathematical matrix methods may be used in a wide variety of physics and engineering applications. Transfer matrix techniques are conceptually and mathematically simple, and they encourage a systems approach. Once one is familiar with one transfer matrix method, it is straightforward to learn another, even if it is from a completely different branch of science. Thus it is useful to overview these methods, and this has been done here. Of special interest are the applications of these methods to laser optics, and matrix theorems concerning multipass optical systems and periodic optical systems …

Nonlinear Robust Control Of A Series Dc Motor Utilizing The Recursive Design Approach, Michael J. Burridge

Retrospective Theses and Dissertations

In this thesis, the investigation of asymptotic stability of the series DC motor with unknown load-torque and unknown armature inductance is considered. The control technique of recursive, or backstepping, design is employed. Three cases are considered. In the first case, the system is assumed to be perfectly known. In the second case, the load torque is assumed to be unknown and a proportional-integral controller is developed to compensate for this unknown quantity. In the final case, it is assumed that two system parameters, load torque and armature inductance, are not known exactly, but vary from expected nominal values within a …

Diagnostic And Adaptive Redundant Robotic Planning And Control, Anya Lynn Tascillo

Graduate Dissertations and Theses

Neural networks and fuzzy logic are combined into a hierarchical structure capable of planning, diagnosis, and control for a redundant, nonlinear robotic system in a real world scenario. Throughout this work levels of this overall approach are demonstrated for a redundant robot and hand combination as it is commanded to approach, grasp, and successfully manipulate objects for a wheelchair-bound user in a crowded, unpredictable environment. Four levels of hierarchy are developed and demonstrated, from the lowest level upward: diagnostic individual motor control, optimal redundant joint allocation for trajectory planning, grasp planning with tip and slip control, and high level task …

Robust Decentralised Variable Structure Control For Rigid Robotic Manipulators, Thasapalan Kuhan

Theses : Honours

In this thesis, the problem of robust variable structure control for non-linear rigid robotic manipulators is investigated. Robustness and convergence results are presented for variable structure control systems of robotic manipulators with bounded unknown disturbances, nonlinearities, dynamical couplings and parameter uncertainties. The major outcomes of the work described in this thesis are summarised as given below. The basic variable structure theory is surveyed, and some basic ideas such as sliding mode designs, robustness analysis and control1er design methods for linear or non-linear systems are reviewed. Three recent variable structure control schemes for robotic manipulators are discussed and compared to highlight …

Cossap Simulation Model Of Ds-Cdma Indoor Microwave Atm Lan, Keng T. Tan

Theses : Honours

This thesis presents an original work in the area of designing and implementing a simulation testbed for modelling a high speed spread spectrum Asynchronous Transfer Mode (ATM) Local Area Network (LAN). The spread spectrum technique used in this LAN model is Direct Sequence Code Division Multiple Access (DS-CDMA). The simulation model includes at least a physical layer of such a LAN, embedded into the COSSAP¹ simulation environment, and has been fully tested. All the newly developed building blocks are comprised of standard blocks from the COSSAP libraries or compatible user-built primitive blocks (only where it is absolutely necessary), and …

Time-Frequency Shift-Tolerance And Counterpropagation Network With Applications To Phoneme Recognition, Li-Minn Ang

Theses : Honours

Human speech signals are inherently multi-component non-stationary signals. Recognition schemes for classification of non-stationary signals generally require some kind of temporal alignment to be performed. Examples of techniques used for temporal alignment include hidden Markov models and dynamic time warping. Attempts to incorporate temporal alignment into artificial neural networks have resulted in the construction of time-delay neural networks. The nonstationary nature of speech requires a signal representation that is dependent on time. Time-frequency signal analysis is an extension of conventional time-domain and frequency-domain analysis methods. Researchers have reported on the effectiveness of time-frequency representations to reveal the time-varying nature of …

Calculating Cross Slot Flux Losses In High Voltage Stator Coils, John D. Amos

Retrospective Theses and Dissertations

At present there are several methods for calculating temperature for inner-cooled stator coils for large electric generators. Determining the highest temperature in a stator coil is very important and is a major limiting factor for the maximum capability of steam turbine synchronous generators.

The load current in the stator winding causes losses in the conductor resistance. That same current excites leakage fluxes that link contours inside the conductors causing non-uniform current distribution and additional losses. these additional losses are caused by eddy currents induced inside the stator coils. These eddy losses are grouped as radial flux losses, cross slot flux …

Finite Impulse Response Utilizing The Principles Of Superposition, Scott Edward Carter

Retrospective Theses and Dissertations

Window functions have been greatly utilized in the synthesis of finite impulse response (FIR) filters implemented using surface acoustic wave (SAW) devices. The critical parameter in any FIR design in the impulse response length, which must be optimized for the given design specifications in order to reduce the size of each device. To this end, many design algorithms have been introduced such as Remez exchange, linear programming, and least mean squares. A new algorithm has been derived which is efficient and accurate for the design of arbitrary filter specifications requiring less computations than the current algorithms. The FIR design is …

Compensation And Characterization Of Gallium Arsenide, Randy A. Roush

Electrical & Computer Engineering Theses & Dissertations

The properties of transition metals in gallium arsenide have been previously investigated extensively with respect to activation energies, but little effort has been made to correlate processing parameters with electronic characteristics. Diffusion of copper in gallium arsenide is of technological importance due to the development of GaAs:Cu bistable photoconductive devices. Several techniques are demonstrated in this work to develop and characterize compensated gallium arsenide wafers. The material is created by the thermal diffusion of copper into silicon-doped GaAs. Transition metals generally form deep and shallow acceptors in GaAs, and therefore compensation is possible by material processing such that the shallow …

Investigation Of The Relationship Between Fuel Injection Nozzle Roto Flow And Hydra Flow And The Engine Torque Of A Diesel Engine, Guang Jin

Dissertations and Theses @ UNI

The purpose of this study was to investigate the possibility of reducing diesel engine torque variation by optimizing fuel injection nozzle tip configuration. In order to reduce engine torque variation, test runs were conducted to determine whether fuel injection nozzles affected diesel engine torque. There was a further effort to determine whether a correlation existed between the fuel injection nozzle roto flow and hydra flow, and the engine torque at specified engine speeds.

Engines installed in cotton pickers and tractors were used for this study. Engines, five from the cotton picker and five from the tractor group were chosen randomly …

Perceived Importance Of Iso 9000 Factors As Indicators Of Quality In Industrial Technology Related Programs At Four-Year State Regional Universities, Floyd L. Olson

Dissertations and Theses @ UNI

Industry has often used a quality standard known as ISO 9000. No evidence has been located demonstrating the applicability of an industrial quality model to a singular academic department. The problem of this study was to determine if the guidelines for ISO 9004-2 could have been considered appropriate for Industrial Technology related programs and how they could have been used to indicate quality within such programs.

The purpose of this study was to seek knowledge relating the importance of ISO 9004-2 guidelines to audit and/or improve the quality management of Industrial Technology related departments at 4-year state regional universities. This …

Identification Of Success Factors In The Implementation Of Computer-Integrated Manufacturing, Dean Harold Jensen

Dissertations and Theses @ UNI

The review of recent literature showed a clear trend within the manufacturing sector toward the integration of design and production activities through increased application of the computer. The competitive advantages of computer integration were reported, as well as increased risk due to the amount of time and capital expended in system implementation. The identification of computer integrated manufacturing (CIM) success factors may reduce this risk.

Prior efforts to identify success factors for other areas of endeavor showed that success factors tended to vary with the four project phases, but were stable over time within a particular phase. More recently, empirical …