Demand for capable and reliable semiconductor and fabrication technology for high temperature and power electronics applications has been increasing in recent years. Silicon Carbide (SiC), as a wide bandgap compound semiconductor, demonstrates superior characteristics such as high thermal conductivity, high breakdown voltage, and long-lasting reliable operation at elevated temperature. SiC-based circuits and systems are capable to offer significant performance enhancements to various applications. Integrated power management units and conversion modules in HEVs, integrated sensors for aircraft engines, development of small-sized portable power generators are among many applications that require reliable circuits with long-lasting functional lifetime. Nevertheless, there are numerous challenges associated with the design and fabrication of SiC-based circuits. The aim of this research is to practically design and implement novel operational amplifiers (opamps) based on Vertical Channel 4H-SiC JFET (SiC JFET) that can be utilized as sub-circuits of integrated SiC JFET-based circuits and systems. Recently, SiC power JFET-based power management units were developed that deploy non-SiC JFET-based circuits for analog signal processing, driving, and control, because all SiC JFET-based circuits were not available for full integration. However, utilizing SiC JFET for analog design (in order to close the mentioned gap) exhibits significant design challenges, even at room temperature. These fundamental challenges are low intrinsic gain, the requirement to limit the gate to source voltage range, and restrictions on utilizing channel length as a design parameter due to fabrication complexity. These challenges must be successfully overcome at room temperature, before moving towards high temperature SiC JFET-based analog design. The main objective of this dissertation is to establish a design base, overcome the challenges, demonstrate the feasibility, and present all SiC JFET-based opamps that are designed for gain, CMRR, and overall performance. Before attempting to design, both Enhancement and Depletion Mode SiC JFETs are characterized, analyzed, and modeled for simulation. Unique and reliable opamp configurations are presented that take design requirements into account, use threshold voltage instead of channel length as a design parameter, and employ gain enhancement techniques while obtaining maximum possible bandwidth. The final opamps are fabricated and tested and the results show that the objective is accomplished.

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The job shop scheduling problem, in which we must determine the order or sequence for processing a set of jobs through several machines in an optimum manner, has received considerable attention. In this paper a number of the methods and techniques are reviewed and an attempt to categorize them according to their appropriateness for effective use in job shop scheduling has been made. Approaches are classified in two categories: a) analytical techniques and b) graphical methods. Also, it should be noticed that this report does not include all the attempts and trials, especially the heuristic approaches.

This paper illustrates Winograd's approach to computing the Discrete Fourier Transform (DFT). This new approach changes the DFT into a cyclic convolution of 2 sequences, and illustrates shortcuts for computing this cyclic convolution. This method is known to reduce the number of multiplies required to about 20% less than the number of multiplies used by the techniques of the Fast Fourier Transform. Three approaches are discussed, one for prime numbers, one for products of primes, and lastly one for powers of odd primes. For powers of 2 Winograd's algorithm is, in general, inefficient and best if it is not used. A computer simulation is illustrated for the 35 point transform and its execution time is compared with that of the Fast Fourier Transform algorithm for 32 points.

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The objective of this research was to develop a framework whereby the United States Naval Surface Forces could be provided with better information to determine their overall readiness capability. This study utilized the new Readiness Assessment and Reporting Standard (S9410-AN-STD-010/AEGIS) as a guide. Also, a System Design Methodology was used as a tool to develop mathematical models for generating the readiness capability for a particular system. The specific system selected for demonstrating this framework was the Gun Weapon System (GWS) being developed for the Arleigh Burke DDG-51 Class Destroyer.

The effects of radiation on an operational amplifier were investigated through simulation. The μA 741 was simulated using Spice. Under normal conditions the 741 had the following properties: offset Voltage (Vos) of 0.8 mV, bias current (IB) of 27 nA, offset current (Ios) of 1 nA, and an open loop gain (A0.1.) of 112 dB. When exposed to neutron fluence of 5 x 10¹³ n/cm², these parameters changed to offset voltage of 45 mV, bias current of 1500 nA, offset current of 500 nA, and an open loop gain of 66 dB. A new circuit is proposed that provides improvements in the above parameters. The modified circuit gives a Vos of 3 mV, IB of 200 nA, Ios of 34 nA and A0.1. of 93 dB following exposure to a neutron fluence of 5 x 10¹³n/cm².

Hazardous waste site remediation cost estimation requires a good estimate of the contaminated soil volume. The United States Environmental Protection Agency (U.S. EPA) currently uses deterministic point values to estimate soil volumes but the literature suggests that probability bounds analysis (PBA) is the more accurate method to make estimates under uncertainty. The underlying statistical theory is that they are more accurate than deterministic estimates because probabilistic estimates account for data uncertainties. However, the literature does not address the problem of selecting an optimal decision point from the interval-valued PBA estimates. The purpose of this study was to identify the optimal PBA decision point estimator and use it to demonstrate that because the PBA method also accounts for data uncertainties, PBA estimates of remedial soil volumes are more accurate than the U.S. EPA deterministic estimates. The research questions focused on determining whether the mean or the 95th percentile decision point is the optimal PBA estimator. A convenience sample of seven sites was selected from the U.S. EPA Superfund Database. The PBA method was used to estimate the remedial soil volumes for the sites. Correlation analyses were performed between the mean and 95th percentile PBA estimates and the actual excavated soil volumes. The study results suggest that the lower bound 95th percentile PBA estimate, which had the best R2-value of 89%, is the optimal estimator. The R2-value for a similar correlation analysis using the U.S. EPA deterministic estimates was only 59%. This confirms that PBA is the better estimator. The PBA estimates are less contestable than the current U.S. EPA deterministic point estimates. Thus, the PBA method will reduce litigation and speed up cleanup activities to the benefit of the U.S. EPA, corporations, the health and safety of nearby residents, and society in general.

What operational factors can explain the performance differences between manufacturing firms? Scholars have produced a significant volume of research that examines the linkages between operational factors (resources and practices) and firm performance. There is agreement that organizational capabilities mediate the relationship between operational factors and firm performance. However, due to the numerous and sometimes contradictory definitions of organizational capabilities in the literature and because organizational capabilities includes non-operational factors, it has been suggested that operational capabilities, as a sub construct of organizational capabilities, is more appropriate for establishing an empirical relationship between operational factors and firm performance. Scholars have argued that process improvement practices facilitate the development of operational capabilities, which can consequently lead to improved firm performance. Other scholars have argued that process improvement practices facilitate organizational knowledge creation, which can also influence firm performance. We integrate these two theoretical perspectives into a single conceptual model that better explains the relationship between knowledge-creating practices and firm operational performance. Specifically, we argue that knowledge-creating practices play a significant role in developing a firm’s operational capabilities, which in turn, influence firm operational performance. This research investigates the existence of a relationship between organizational knowledge creation and firm operational performance that is mediated by operational capabilities.