Browsing by Subject "LabVIEW"
Now showing 1 - 6 of 6
Results Per Page
Sort Options
Item A versatile simulation tool for virtual implementation of proportional integral and derivative (PID) controllers(Texas A&M University, 2007-09-17) Ramamurthi, InduThis thesis proposes an interactive software tool that can be used to compute complete sets of Proportional Integral Derivative (PID) Controllers from knowledge of the plant transfer function/frequency response data. This is based on research results and algorithms developed by Bhattacharyya and others. Until these research results were published, it was not known if a nominal system could be stabilized using PID Controllers, and current PID Controller designs are carried out using ad hoc tuning rules. By using simulations, engineers can best plan for and observe the stabilizing effect each of the variables has on system performance in a realistic environment. The software application developed calculates and optimizes complete stabilizing sets of PID Controllers for a rational Linear Time Invariant (LTI) system, and has been developed for analytical models of plants with and without time delay. Further, these PID Controller sets are optimized to project subsets simultaneously satisfying multiple performance index specifications. Sets of PID Controllers that stabilize a system are also calculated automatically from knowledge of the frequency response of the plant. It allows the user ease of design and the ability to customize the final solution while permitting full control over source parameters. This thesis includes an introduction to the algorithms that have been developed for plant stabilization, a complete description of the graphical user interface, the simulation of the algorithms performed using LabVIEW, and a summary of future work.Item A web interface design for a plasma etcher(Texas Tech University, 1999-05) Hossain, Tasnim MuradIt is mentioned that the objective of this project is to make a particular semiconductor processing equipment over the Internet but the approach for achieving the objective was made generic so that it can be applied to achieve remote access to any other piece of expensive equipment.Item Automated sleep scoring system using labview(Texas A&M University, 2006-04-12) Deshpande, Parikshit BapusahebSleep scoring involves classification of polysomnographic data into the various sleep stages as defined by Retschaffen and Kales. This process is time-consuming and laborious as it involves experts visually scoring the data. During recent years, there has been an increasing focus on automated sleep scoring systems and professional software programs are finding increased use. However, these systems are not relied on for scoring and are often used as a tool that facilitates easy visual scoring. This thesis proposes a neural network based approach to automatic sleep scoring using LabVIEW. Effort has been made to give the sleep expert more control over key parameters such as the frequency bands, and thus come up with scores that are more in agreement with the individual scorer than being a rigid interpretation of the R&K rules. Though this thesis is limited to the development of an offline software program, given the data acquisition facilites in LabVIEW, a complete system from data acquisition to sleep hypnograms is a fair possibility.Item Diagnostics of subsynchronous vibrations in rotating machinery - methodologies to identify potential instability(Texas A&M University, 2005-11-01) Kar, RahulRotordynamic instability can be disastrous for the operation of high speed turbomachinery in the industry. Most ??instabilities?? are due to de-stabilizing cross coupled forces from variable fluid dynamic pressure around a rotor component, acting in the direction of the forward whirl and causing subsynchronous orbiting of the rotor. However, all subsynchronous whirling is not unstable and methods to diagnose the potentially unstable kind are critical to the health of the rotor-bearing system. The objective of this thesis is to explore means of diagnosing whether subsynchronous vibrations are benign or have the potential to become unstable. Several methods will be detailed to draw lines of demarcation between the two. Considerable focus of the research has been on subharmonic vibrations induced from non-linear bearing stiffness and the study of vibration signals typical to such cases. An analytical model of a short-rigid rotor with stiffness non-linearity is used for numerical simulations and the results are verified with actual experiments. Orbits filtered at the subsynchronous frequency are shown as a diagnostic tool to indicate benign vibrations as well as ??frequency tracking?? and agreement of the frequency with known eigenvalues. Several test rigs are utilized to practically demonstrate the above conclusions. A remarkable finding has been the possibility of diagnosing instability using the synchronous phase angle. The synchronous phase angle ?? is the angle by which the unbalance vector leads the vibration vector. Experiments have proved that ?? changes appreciably when there is a de-stabilizing cross coupled force acting on the rotor as compared to when there is none. A special technique to calculate the change in ?? with cross-coupling is outlined along with empirical results to exemplify the case. Subsequently, a correlation between the synchronous phase angle and the phase angle measured with most industrial balancing instruments is derived so that the actual measurement of the true phase angle is not a necessity for diagnosis. Requirements of advanced signal analysis techniques have led to the development of an extremely powerful rotordynamic measurement teststand ?? ??LVTRC??. The software was developed in tandem with this thesis project. It is a stand-alone application that can be used for field measurements and analysis by turbomachinery companies.Item Eight-Channel Head Array and Control System for Parallel Transmit/Receive Magnetic Resonance Imaging(2014-08-11) Moody, KatherineInterest in magnetic resonance imaging (MRI) at high fields strengths (3 Tesla and above) is driven by the associated improvements in signal-to-noise ratio and spectral resolution. In practice, however, technical challenges prevent these benefits from being straightforwardly realized. High fields are associated with an increase in frequency and a decrease in the radiofrequency (RF) wavelength. The shortened wavelength causes potential inhomogeneity in the transmit field of the RF coil, resulting in non-uniform excitations. Susceptibility effects are also more pronounced at high field strengths, and can cause local distortions in the field and create areas of signal dropout. Parallel transmit is one method in development to address these challenges at high fields. Parallel transmit involves using multiple independently driven channels with RF pulses varying in amplitude, phase, and pulse envelope to create desired transmit excitations. Parallel transmit has been implemented to create homogenous transmit patterns and compensate for magnetic susceptibility effects, but despite its proven usefulness, the technology has yet to receive widespread adoption. Few parallel transmit systems exist and little work has been done in the pre-clinical realm. Studies demonstrating the clinical benefits of parallel transmit constitute a gap in the current body of work. This works presents an approach to a parallel transmit array and control system that can be easily and safely integrated on a clinical whole-body scanner. The transmit array was designed for use with ultra-low output impedance amplifiers and demonstrates an array design with a simplified decoupling network augmented by amplifier decoupling in both transmit and receive. The control system was programmed in LabVIEW using off-the-shelf hardware to manage pulse playback, correct transmit chain non-linearities, monitor on-coil waveforms, and drive the transmit hardware. The transmit array was shown with well-isolated patterns, and parallel transmit capability was demonstrated. This work progressed the translation of experimental parallel transmit technology to pre-clinical use.Item Equipment control and computer interfacing using LabVIEW(Texas Tech University, 2000-05) Mahmud, MuhiuzzamanThis thesis describes two control projects undertaken at the Maddox Laboratory of the Texas Tech University. The first project concerns digital image data acquisition from a CCD chip into a PC. The second project deals with the control of a Magnetron Sputtering equipment and its accessories. Both the projects culminate to working LabVIEW programs that automate the controls for both the systems. CCD sensors can be classified broadly into two categories - the linear sensors and the area sensors. The sensor used in the data acquisition project was an area sensor of the "full-frame" type. A matrix of photo-ensitive CCD pixels generate electron packets of varying charge content that is proportional to the amount of incident photons. After a finite integration period, during which photo-generated electronic charges accumulate within the potential well of each CCD photo-site, the whole field of pixels is shifted towards the output node. This shift towards the output node occurs in several steps. First, a Vertical shift clock pulse causes all the rows to be shifted downwards by one position -resulting into the bottom row being shifted to a serial shift register. A series of, Horizontal-Shift clock pulses then shift out the pixels one by one through the shift register into the output diffusion node. The output diffusion is voltage modulated by the charge content in a pixel. This voltage is sensed by an output buffer amplifier. After all the pixels in a row have been shifted out to the floating diffusion at the output and sensed by the output amplifier, a row shift occurs again and the same sequence is repeated.