Browsing by Subject "Diagnostic"
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Item Computer algorithm to detect and predict machine faults using cloud-based vibration data(2015-05) Olivares Villamediana, Ignacio Javier; Fernandez, Benito R.; Bukowitz, DavidIn this research a machine fault detection and diagnostic algorithm is presented. The algorithm uses time wave-form acceleration data stored in a server for cloud computing to calculate RMS and Peak values from it and give information to the user for maintenance schedule. Detection algorithm analyses the change in time of the acceleration signals and establish urgency and severity of the studied machines. Furthermore, the diagnosis sub-system studies also the change in time of the signals in frequency domain to give a forecast of the possible existing fault by discarding faults throughout a predetermined decision table. Simulated and real cases are performed to show the efficiency and results of using the algorithm as well.Item Diagnostics for the Texas Petawatt laser-plasma accelerator(2010-08) Du, Dongsu, 1985-; Downer, Michael CoffinSince 2004, table-top laser-plasma accelerators (LPAs) driven by ˜30fs terwatt laser pulses have produced colimated, nearly mono-energetic eletron bunches with energy up to 1 GeV in laboratories around the world. Large-scale computer simulations show that LPAs can scale to higher energy while retaining high beam quality, but will require laser pulses of higher energy and longer duration than current LPAs. The group of Prof. Mike Downer, in collaboration with the Texas Petawatt (TPW) laser team headed by Prof. Todd Ditmire, is setting up an experiment that uses the TPW laser (1.1 PW, 150 fs) to drive the world’s first multi-GeV LPA. This thesis provides a general overview of the TPW-LPA project, including several diagnostic systems for the beam, plasma and laser pulse. Special attention is given to three of the diagnostic systems: (1)A transverse interferometry diagnostic of the plasma density profile created by the TPW laser pulse; (2)A Thomson scattering diagnostic of the self-guided path of the TPW laser pulse through the plasma; (3)An optical transition radiation diagnostic of the accelerated electron bunch exiting the plasma. In each case, basic principles, theoretical background, calculation and simulation results, and preliminary experimental results will be presented.Item Making sense of speech : a practical approach to pronunciation assessment(2014-12) Kroman, Steven Andrew; Garza, Thomas J.Recent research has shifted the focus of pronunciation instruction from achieving native-like speech in learners to correcting issues that affect the intelligibility of the learners’ speech. Research also suggests that suprasegmental features of pronunciation, such as intonation, rhythm, and stress, have a considerable influence on intelligibility. By using Dickerson’s (1989) Covert Rehearsal Model, which includes predictive strategies that encourage learner autonomy, instructors have the tools necessary to effectively help learners improve their intelligibility. However, the question as to which instructional targets should be taught in the classroom still remains. This report outlines one way in which instructors can use a diagnostic assessment in order to discover which instructional targets are most appropriate for their learners.Item Measuring Hydroxyl Radicals during the Oxidation of Methane, Ethane, Ethylene, and Acetylene in a Shock Tube Using UV Absorption Spectroscopy(2013-05-02) Aul, Christopher JThe hydroxyl (OH) radical is a common intermediate species in any hydrogen- or hydrocarbon-based flame. Investigating OH at elevated temperatures and pressures is not a trivial task, and many considerations must be made to fully study the molecule. Shock tubes can provide the experimenter with a wide range of temperatures and pressures to investigate a variety of combustion characteristics including, but not limited to, OH kinetic profiles. Described in this dissertation is the diagnostic used to measure OH within a shock tube using UV absorption spectroscopy from an enhanced UV Xenon lamp passed through a spectrometer. OH absorption was made over a narrow range of wavelengths around 309.551 nm within the widely studied OH X?A ground vibrational transition region. Experiments have been performed in the shock-tube facility at Texas A&M University using this OH absorption diagnostic. A calibration mixture of stoichiometric H2/O2 diluted in 98% argon by volume was tested initially and compared with a well-known hydrogen-based kinetics mechanism to generate an absorption coefficient correlation. This correlation is valid over the range of conditions observed in the experiments at two pressures near 2 and 13 atm and temperatures from 1182 to 2017 K. Tests were completed using the absorption coefficient correlation on stoichiometric mixtures of methane, methane and water, ethane, ethylene, and acetylene to compare against a comprehensive, detailed chemical kinetics mechanism which considers up through C5 hydrocarbons. Measurements of methane show good agreement in peak OH formation and ignition delay time when compared with the mechanism. Improvements can be made in the shape of the methane-oxygen OH profile, and sensitivity and rate of production analyses were performed with the mechanism to identify key reactions for tuning. Similar results were found for methane-water-oxygen mixtures with no difference in profile shape or ignition delay time noted. There is room for improvement between the mechanism and measured values of OH for ethane-, ethylene-, and acetylene-based mixtures, although interesting pre-ignition features are nonetheless captured relatively well by the mechanism. Uncertainty in the measurement comes from the inherent noise in the photomultiplier tube signal and is ?25-150 ppm for the 2-atm experiments and ?6-25 ppm for the 13-atm experiments.Item Nucleic acid circuit and its application in genetic diagnostic(2016-05) Jiang, Yu; Ellington, Andrew D.; Brodbelt, Jennifer S.; Crooks, Richard M.; Anslyn, Eric V.; Finkelstein, Ilya J.DNA can execute programmed strand exchange reactions that process signals and information. In particular, toehold-mediated strand exchange, a process in which one strand of a hemi-duplex is replaced by another, single strand to create a more stable complex, is the basis for many DNA circuits. By engineering several strand exchange reactions in a systematic way, complex DNA circuits can be created that accomplish sophisticated control tasks, similar to an electronic circuit. In this dissertation, we will demonstrate how we engineered and improved a toehold-mediated strand exchanged-based reaction, catalytic hairpin assembly (CHA), to make it into a real-world nucleic acid diagnostic. While CHA has previously been shown to act as an excellent amplifier of nucleic acid signals, it can sometimes execute non-specifically even in the absence of catalyst, limiting signal-to-noise and limits of detection. By introducing two mismatched bases into a specific domain on the circuit, the background leakage can be greatly decreased and the signal-to-noise ratio can be improved from less than 10 to over 100. However, the improvement of the signal:background ratio still cannot increase sensitivity compatible to the enzyme-based nucleic acid amplification. Still, DNA circuits can improve upon background issues inherent in isothermal amplification reactions, which often produce spurious side products. We engineered DNA circuits that were thermostable from 37 °C to 60 °C and used these for the real-time detection of isothermal amplification reactions. These circuits in essence acted like an additional probe to measure the accumulation of correct, rather than spurious, amplicons. One isothermal amplification reaction, loop-mediated isothermal amplification (LAMP) combined with our DNA could detect particular alleles of M. tuberculosis RNA polymerase (rpoB) in sputum and of the melanoma-related biomarker BRAF. As one more step towards generating a true point-of-care (POC) test, we engineered DNA circuits to transduce amplicons into an off-the-shelf glucometer. Using these reactions and devices we could directly transduce Middle-East respiratory syndrome coronavirus (MERS) and Zaire Ebolavirus (Ebola) templates into glucose signals, with a sensitivity as low as 20-100 copies/µL. Virus from cell lysates and synthetic templates could be readily amplified and detected even in sputum or saliva. An OR gate that coordinately triggered on viral amplicons further guaranteed fail-safe virus detection.