Now showing items 9176-9195 of 14895

    • A multi-tasking operating system for real-time applications

      Williams, Ted L.; Brinkmeyer, Jay Charles, 1960- (The University of Arizona., 1987)
      Presented in this thesis is the design and implementation of a fast, compact, and flexible multi-tasking operating system. This system is designed for use in small computers which must deliver real-time performance in extremely constrained environments. The operating system is implemented in the "C" language to allow portability between different computers systems. A number of useful features are provided which support dynamic task management, message passing, a hierarchial file system, device drivers, and a command line interpreter. Modularized construction enables the user to prune unnecessary system features for specific applications. Presently, the system is operational on a personal computer which is also used for system development. This serves as a realistic environment for testing system response to real-time events.
    • A multi-wavelength optical content-addressable parallel processor (MW-OCAPP) for high-speed relational database processing: Free-space experimental implementation and monolithic adaptation based on guided-wave technology

      Louri, Ahmed; Detofsky, Abram Maximilian (The University of Arizona., 1999)
      This thesis explores the five-space experimental implementation and monolithic adaptation of the Equality subsystem from a parallel relational database optical machine called the Multi-Wavelength Optical Content-Addressable Parallel Processor (MW-OCAPP). MW-OCAPP uses a novel polarization- and wavelength-encoding scheme to achieve an input/output-limited experimental peak bit comparison rate of 96,000/sec. Recognizing the severe diffraction-limit penalty for using a free-space optical processor with relatively long path lengths, a system based on guided-wave optics called the Equivalency Processing Parallel Photonic Integrated Circuit (EP3IC) was developed. Although algorithmically identical to MW-OCAPP's equality operation, EP3IC's peak bit comparison rate for a similarly configured machine is over six orders of magnitude faster. It achieves this substantial performance advantage by making use of integrated high-speed detectors and electro-optic modulators. This integrated circuit solution provides relatively low-power operation, fast switching speed, a compact system footprint, vibration tolerance, and a design that is highly manufacturable.
    • Multiaxial cyclic testing of saturated Ottawa sand

      Desai, Chandrakant S.; Gyi, Maung Maung (The University of Arizona., 1996)
      Static and dynamic behavior of the dry and saturated Ottawa sand are studied in the constitutive modeling laboratory, by using cubical multiaxial device with servo-controlled loading system and high speed automatic data acquisition system. In this investigation, the multiaxial cubical device with servo-controlled loading system and high speed automatic data acquisition system is used to apply independently the three-dimensional loading and measure corresponding strains and stress. The cubical multiaxial device is modified to include the servo-controlled pressure system and automatic data acquisition system. To understand the cyclic behavior and post cyclic behavior, comprehensive laboratory tests have been performed on the dry and saturated Ottawa sand, covering a number of relative densities and confinements.
    • A multibody model simulating tilt-wing conversion

      Nikravesh, Parviz E.; O'Heron, Patrick James, 1966- (The University of Arizona., 1991)
      A multibody model is presented which simulates the conversion process associated with tilt-wing aircraft. A multibody dynamics approach is used to derive the equations of motion for a tilting articulated rotor with flap-pitch-lag root geometry. An enhanced model is used for the near-wake aerodynamics and uniform dynamic-inflow is used for the far-wake aerodynamics. A thrust control system computes the required trim settings. It is found that the controller can "fly" the model to a hover condition at a desired altitude, and can be used to achieve desired thrust levels during conversion. It is noted that conventional blade twist is inadequate during conversion. It is observed that unsteady aerodynamics are important during conversion. Also nonlinear effects on the tilt-wing cause large variations in tilt-torque during conversion.
    • Multicriterion modeling of wastewater management : a comparison of techniques

      Tecle, Aregai; Duckstein, Lucien; Sorooshian, Soroosh (The University of Arizona., 1986)
      Multicriterion modeling of wastewater management problem is presented in order to select the most preferred wastewater scheme. The Nogales International Wastewater Treatment Plant which serves the binational cities of Nogales, Arizona and Nogales, Sonora is used as case study in the modeling process. The process includes identifying of objectives, specifying of treatment alternatives and defining criteria to relate the objective satisfactum level to the alternative schemes. Six different multicriterion decision making techniques are applied to analyze and obtain preference ordering among the alternative treatment schemes. Analyses on the individual techniques and comparison among them are performed to arrive at the following conclusions: (1) all the techniques except one can be confidently used to obtain complete ordering of alternatives, (2) there is inter-model consistency in the ordering process, (3) in performing this function, the techniques are fairly robust with respect to parameter changes, and (4) only two treatment alternatives of fifteen considered are consistently ranked higher than the rest.
    • A multidisciplinary analysis of the hydrogeology of the Maricopa superconducting super collider (SSC) site, Maricopa County, Arizona

      Davis, Stanley N.; Brooks, Steven John, 1959- (The University of Arizona., 1988)
      Geology and tunnelling was given by the U.S. Department of Energy (DOE) as the most important criteria in siting the SSC. The impact of ground water on construction and vice-versa is an important part of a sites geologic and tunnelling attributes, and its potential environmental impacts. Because of the site's undeveloped nature, only limited reconnaissance-type investigations of the regions hydrogeology had occurred prior to the siting of the SSC. To overcome this ignorance geological, geotechnical, and geophysical characteristics of the site were used to describe the hydrogeology. A hydrologically ideal site would lie above any aquifers, have little or no surface water interaction, and yet, have an adequate and reliable supply of good quality water nearby. The Maricopa site possesses all of these characteristics while apparently being absent of subsidence due to ground-water withdrawal.
    • Multilevel subcarrier multiplexing in optical fiber communications

      Liu, Ming-Kang; Modestou, Panayiotis Charalambous, 1967- (The University of Arizona., 1993)
      The primary aim of the thesis is to determine the spectrum efficiency and power penalty of multi-level Subcarrier Multiplexing (SCM) transmission. To perform quantitative analysis, this thesis first develops a fiber transmission model. When there is one SCM transmission channel, it is found that the power penalty due to multi-level is 5 dB per bit at the same bit error rate (BER). For multiple channel SCM transmission, to reduce adjacent channel interference (ACI), it is found that binary transmission has the best spectrum efficiency for Non-Return-to-Zero (NRZ) pulses at the same BER. However, if raised-cosine pulses are used, 32-ary transmission is found to be the most efficient in spectrum use because of the smaller ACI.

      SARRIA, ALEJANDRO. (The University of Arizona., 1999)

      Zak, Francis Anthony. (The University of Arizona., 1983)

      Cheraghi, Seyed Hossein, 1957- (The University of Arizona., 1987)
    • Multiple choice modular design when linear and separable constraints are present

      Goldberg, Jeffery B.; Zhu, Ji, 1964- (The University of Arizona., 1988)
      In this thesis we give two extensions to the multiple choice modular design problem. In the first case, we consider the situation that parts are purchased from different vendors. In the second case, we consider the situation that linear and separable constraints are present in our model. We propose a heuristic for solving each of the problems. Some computational results are included.
    • Multiple linear regression models for predicting trihalomethane formation from chlorinated natural waters

      Fraas, Tracy Beth.; Amy, Gary L. (The University of Arizona., 1984)
      A USEPA survey in 1975 found trihalomethanes (THMs) to be widespread in chlorinated drinking water. A subsequent study identified humic substances as probable precursors. In 1976, the National Cancer Institute found chloroform to cause cancer in laboratory rats. Consequently, the USEPA set a maximum contaminant level (MCL) of 100 pg/1 for total THMs in drinking water systems. THM formation reactions between chlorine and humic substances have been studied but are not completely understood. Parameters found to affect THM formation rate and concentration are raw water pH, temperature, and bromide level; precursor source and concentration, chlorine dose, and chlorine contact (reaction) time. This research involved the formulation of empirically derived models, enabling THM prediction as a function of time and parameters, for natural waters. Kinetic experiments, designed to vary parameters, were conducted on seven geographically diverse natural waters. THM concentrations were analyzed by gas chromatography. Models were developed using multiple linear regression. Three predictive models were chosen based on statistical analysis and were tested on four natural waters. All models predicted well for ambient water conditions. No single model predicted better overall. Variations in the "reactivity" of waters due to precursor source were not adequately predicted, nor were chlorine-limited conditions.
    • Multiple personality disorder in conjunction with satanic ritual abuse, an educational training film: A survey of need

      Newlon, Betty; Brockman, Pamela Faye, 1948- (The University of Arizona., 1992)
      The issue of satanic ritual abuse has gained widespread public and professional attention in the past ten years. During therapy, many adult Multiple Personality Disorder (MPD) clients describe memories of Satanic Ritual Abuse (SRA) beginning in childhood. Basically, the only information circulating in the mental health professional community about MPD/SRA issues is derived from workshops and lectures at trainings and professional meetings. The intent of this project was to determine the need for an in-depth educational training film for mental health professionals to assess, diagnose and treat satanic ritual abuse survivors in conjunction with multiple personality disorder. A questionnaire was used to determine whether a video educational training film would be beneficial. The conclusion was reached that an educational training film would be useful in helping mental health professionals. It was also concluded that educational training films in the behavioral sciences is an effective training tool.
    • Multiple plate printmaking, vehicle for a journey into the invisible

      Brownlee, George Harlan, 1938- (The University of Arizona., 1968)
    • Multiple source testing of camera systems

      Rodrigues-Torres, Cristobal, 1941- (The University of Arizona., 1970)
    • Multiple user communications for telescience

      Schooley, Larry C.; Doser, Adele Beatrice, 1967- (The University of Arizona., 1992)
      This thesis presents a software development which allows multiple users to command, control, and communicate with an experiment occurring at some distant location. These functions were implemented through the modification of software already in existence in the Telescience Laboratory. There were two important items which needed to be developed in order to accommodate the desired transition: handling multiple connections and managing user privileges. The former was implemented by the reformulation of TCP/IP protocol software. The second item necessitated the development of a key assignment scheme. Steps leading up to the final design are discussed. The software package OASIS is used throughout to constitute the user-machine interface. As an application for this multiple user technology, a simulation of a Martian oxygen production plant is commanded and controlled remotely.
    • Multiplex planning

      Sistrunk, Ronnie Hugh, 1946- (The University of Arizona., 1974)
    • Multiplexing Holographic Waveguide Couplers in Photopolymer Material

      Kostuk, Raymond K.; Nguyen, Jilian; Blanche, Pierre-Alexandre; Hua, Hong (The University of Arizona., 2020)
      Augmented Reality headsets that are viable for the consumer market still face many optical challenges, including a limited field of view and complexity of the headset. The well-known current architectures such as HoloLens and Magic Leap employ surface relief grating coupler waveguides to produce images for the user. These waveguides are limited in FOV and can add bulk to the overall system. Volume holograms as waveguide couplers can be another solution to produce images for the user. This thesis discusses the theory behind volume holograms for use in augmented reality waveguide optical applications. Current generation AR solutions are discussed and the potential of photopolymer hologram material to match current optical specifications is simulated. For scalability and ease of manufacturing, the recording of such holograms should be at least as efficient and as costly as SRG couplers. A method to monitor the material response for better control of diffraction efficiency is described and used to experimentally verify the recording of a transmission hologram coupler for a waveguide. The same method is used to record a multiplexed transmission hologram coupler which verified simulations for multiplexed gratings. Expanded FOV is demonstrated with the multiplexed transmission hologram coupler. The capabilities and limitations of a commercially available photopolymer recording material are discussed along with techniques for future studies that can improve the performance of volume hologram couplers.