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 Degree Discipline: Engineering Technology
 Collection: UNT Theses and Dissertations
Characterization of boron nitride thin films on silicon (100) wafer.

Characterization of boron nitride thin films on silicon (100) wafer.

Date: August 2007
Creator: Maranon, Walter
Description: Cubic boron nitride (cBN) thin films offer attractive mechanical and electrical properties. The synthesis of cBN films have been deposited using both physical and chemical vapor deposition methods, which generate internal residual, stresses that result in delamination of the film from substrates. Boron nitride films were deposited using electron beam evaporation without bias voltage and nitrogen bombardment (to reduce stresses) were characterize using FTIR, XRD, SEM, EDS, TEM, and AFM techniques. In addition, a pin-on-disk tribological test was used to measure coefficient of friction. Results indicated that samples deposited at 400°C contained higher cubic phase of BN compared to those films deposited at room temperature. A BN film containing cubic phase deposited at 400°C for 2 hours showed 0.1 friction coefficient.
Contributing Partner: UNT Libraries
Characterization of iron oxide deposits formed at Comanche Peak Steam Electric Station (CPSES)

Characterization of iron oxide deposits formed at Comanche Peak Steam Electric Station (CPSES)

Access: Use of this item is restricted to the UNT Community.
Date: May 2003
Creator: Namduri, Haritha
Description: The presence of deposits leading to corrosion of the steam generator (SG) systems is a major contributor to operation and maintenance cost of pressurized water reactor (PWR) plants. Formation and transport of corrosion products formed due to the presence of impurities, metallic oxides and cations in the secondary side of the SG units result in formation of deposits. This research deals with the characterization of deposit samples collected from the two SG units (unit 1 and unit 2) at Comanche Peak Steam Electric Station (CPSES). X-ray diffraction (XRD), Fourier transform infrared spectrophotometry (FTIR), scanning electron microscopy (SEM), and energy dispersive spectroscopy (EDS) techniques have been used for studying the compositional and structural properties of iron oxides formed in the secondary side of unit 1 and unit 2. Magnetite (Fe3O4) was found to be predominant in samples from unit 1 and maghemite (g-Fe2O3) was found to be the dominant phase in case of unit 2. An attempt has been made to customize FTIR technique for analyzing different iron oxide phases present in the deposits of PWR-SG systems.
Contributing Partner: UNT Libraries
A Computer-Based Process Control System for a Target Station in a LINAC Facility

A Computer-Based Process Control System for a Target Station in a LINAC Facility

Date: May 1999
Creator: Al-Shantaf, Abdulraouf O.
Description: An event-driven, sequential, process control system was designed for International Isotopes, Inc., to automate and remotely control a target station at the company's linear accelerator facility. The designed system consisted of two major sections: a software program (virtual instrument), which was developed by LabVIEW, and a hardware interface (FieldPoint Modular Distributed I/O System by National Instrument), which had to be a pre-developed system that did not require customization. The designed virtual instrument was tested on a simulation model that mimed the target station. The result was a valid design.
Contributing Partner: UNT Libraries
Computer virus spread containment using feedback control.

Computer virus spread containment using feedback control.

Date: December 2004
Creator: Yelimeli Guruprasad, Arun
Description: In this research, a security architecture based on the feedback control theory has been proposed. The first loop has been designed, developed and tested. The architecture proposes a feedback model with many controllers located at different stages of network. The controller at each stage gives feedback to the one at higher level and a decision about network security is taken. The first loop implemented in this thesis detects one important anomaly of virus attack, rate of outgoing connection. Though there are other anomalies of a virus attack, rate of outgoing connection is an important one to contain the spread. Based on the feedback model, this symptom is fed back and a state model using queuing theory is developed to delay the connections and slow down the rate of outgoing connections. Upon implementation of this model, whenever an infected machine tries to make connections at a speed not considered safe, the controller kicks in and sends those connections to a delay queue. Because of delaying connections, rate of outgoing connections decrease. Also because of delaying, many connections timeout and get dropped, reducing the spread. PID controller is implemented to decide the number of connections going to safe or suspected queue. Multiple ...
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Cost savings realized through proper sizing of an excessive instrument air system.

Cost savings realized through proper sizing of an excessive instrument air system.

Date: December 2003
Creator: Condron, Ewell D.
Description: The purpose of this research was to determine if installing a smaller air compressor could reduce the electrical usage of a large semiconductor manufacturing plant. A 200 horsepower Atlas Copco compressor was installed with the existing 500 horsepower Ingersoll-Rand compressors. Testing was conducted during the regular manufacturing process at MEMC Southwest in Sherman, Texas. Analysis of the data found that installing the new compressor could reduce electrical consumption. The study also found there are specific operational setpoints that allow the compressor to operate more efficiently.
Contributing Partner: UNT Libraries
A Data Acquisition System Experiment for Gas Temperature and Pressure Measurements on a Liquid-Nitrogen-Powered Vehicle

A Data Acquisition System Experiment for Gas Temperature and Pressure Measurements on a Liquid-Nitrogen-Powered Vehicle

Date: May 1998
Creator: Lui, Samson Sze-Sang
Description: A data acquisition system was set up to measure gas temperatures and pressures at various points on a liquid-nitrogen-powered vehicle. The experiment was attempted to develop a data acquisition method for applications on engines that use liquid air as the fuel. Two thermocouples and a pressure transducer were connected using data acquisition instruments interfaced to a laptop computer to acquire data.
Contributing Partner: UNT Libraries
Design of a Monitoring System for a Plasma Cleaning Machine

Design of a Monitoring System for a Plasma Cleaning Machine

Date: May 1999
Creator: Fooks, Terry M. (Terry Max)
Description: Plasma cleaning is the most effective dry process to remove surface contaminates from a SAW (Surface Acoustical Wave) device. Consistent gas pressures, flows, and good electrical connections between the chamber shelves are necessary for the process to function predictably. In addition, operation of the monitoring system must be transparent to the plasma cleaning unit. This thesis describes a simple solution to the complex problem of monitoring a plasma cleaning system. The monitoring system uses the LabVIEW® G programming language and hardware, both products of National Instruments, Inc.®, to monitor critical parameters necessary to achieve a consistent process when cleaning these devices.
Contributing Partner: UNT Libraries
Design of Power Amplifier Test Signals with a User-Defined Multisine

Design of Power Amplifier Test Signals with a User-Defined Multisine

Access: Use of this item is restricted to the UNT Community.
Date: May 2004
Creator: Nagarajan, Preeti
Description: Cellular radio communication involves wireless transmission and reception of signals at radio frequencies (RF). Base stations house equipment critical to the transmission and reception of signals. Power amplifier (PA) is a crucial element in base station assembly. PAs are expensive, take up space and dissipate heat. Of all the elements in the base station, it is difficult to design and operate a power amplifier. New designs of power amplifiers are constantly tested. One of the most important components required to perform this test successfully is a circuit simulator model of an entire communication system that generates a standard test signal. Standard test signals 524,288 data points in length require 1080 hours to complete one test of a PA model. In order to reduce the time taken to complete one test, a 'simulated test signal,' was generated. The objective of this study is to develop an algorithm to generate this 'simulated' test signal such that its characteristics match that of the 'standard' test signal.
Contributing Partner: UNT Libraries
Determination of the shelf life of aluminum electrolytic capacitors.

Determination of the shelf life of aluminum electrolytic capacitors.

Date: May 2002
Creator: Wynne, Edward McFaddin
Description: The aluminum electrolytic capacitor is used extensively in the electric utility industry. A factor limiting the storage of spare capacitors is the integrity of the aluminum oxide dielectric, which over time breaks down contributing to a shelf life currently estimated at one nuclear power electric generating station to be approximately five years. This project examined the electrical characteristics of naturally aged capacitors of several different styles to determine if design parameters were still within limits. Additionally, the effectiveness of a technique known as “Reforming” was examined to determine its impact on those characteristics.
Contributing Partner: UNT Libraries
Development of a coaxiality indicator

Development of a coaxiality indicator

Access: Use of this item is restricted to the UNT Community.
Date: December 1999
Creator: Arendsee, Wayne C.
Description: The geometric dimensioning and tolerancing concept of coaxiality is often required by design engineers for balance of rotating parts and precision mating parts. In current practice, it is difficult for manufacturers to measure coaxiality quickly and inexpensively. This study examines feasibility of a manually-operated, mechanical device combined with formulae to indicate coaxiality of a test specimen. The author designs, fabricates, and tests the system for measuring coaxiality of holes machined in a steel test piece. Gage Repeatability and Reproducibility (gage R&R) and univariate analysis of variance is performed in accordance with Measurement System Analysis published by AIAG. Results indicate significant design flaws exist in the current configuration of the device; observed values vary greatly with operator technique. Suggestions for device improvements conclude the research.
Contributing Partner: UNT Libraries
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