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<p>Accurate characterization of a noisy device starts with an accurate measurement system. Measurement uncertainty and error continues to be a challenging subject as technology advances. The conventional method to noise characterization of on-wafer devices is to determine its noise parameters. To extract the noise parameters of an unpackaged device involves a sophisticated measurement system and calibration procedure. This thesis presents a new automated on-wafer noise measurement system based on Labview 8.5.1 which is used to examine measurement uncertainty for noise parameter extraction. The software program can be used and customized for a wide range of on-wafer noise measurements. This thesis covers the design and operation of the measurement system, which is then used to analyze measurement uncertainty.</p> <p>Measurement uncertainty can be due to various sources from environmental surroundings to instrument settings and the components of the system itself. In many scenarios, inaccuracies are random and cannot be completely resolved. In this thesis, a new tuner characterization technique that improves source tuner characterization is presented. Additionally, a new gain compensation technique is applied to measured noise powers that attempt to improve noise parameter extraction accuracy is proposed. The tuner characterization technique is evaluated against a current industry solution and the affects of the gain compensation technique is evaluated using a newly developed figure of merit. This research work concludes that a direct noise power correction is valid and necessary to further improve noise parameter accuracy. However, the proposed technique when applied resulted in minimal change to the overall noise parameter data. It is found that that source termination selection and total points used for fitting continue to be the major source of uncertainty for noise parameter accuracy.</p> / Master of Applied Science (MASc)

Wind tunnel experiments will continue to be a primary source of validation data for many types of mathematical and computational models in the aerospace industry. The increased emphasis on accuracy of data acquired from these facilities requires understanding of the uncertainty of not only the measurement data but also any correction applied to the data. One of the largest and most critical corrections made to these data is due to wall interference. In an effort to understand the accuracy and suitability of these corrections, a statistical validation process for wall interference correction methods has been developed. This process is based on the use of independent cases which, after correction, are expected to produce the same result. Comparison of these independent cases with respect to the uncertainty in the correction process establishes a domain of applicability based on the capability of the method to provide reasonable corrections with respect to customer accuracy requirements. The statistical validation method was applied to the version of the Transonic Wall Interference Correction System (TWICS) recently implemented in the National Transonic Facility at NASA Langley Research Center. The TWICS code generates corrections for solid and slotted wall interference in the model pitch plane based on boundary pressure measurements. Before validation could be performed on this method, it was necessary to calibrate the ventilated wall boundary condition parameters. Discrimination comparisons are used to determine the most representative of three linear boundary condition models which have historically been used to represent longitudinally slotted test section walls. Of the three linear boundary condition models implemented for ventilated walls, the general slotted wall model was the most representative of the data. The TWICS code using the calibrated general slotted wall model was found to be valid to within the process uncertainty for test section Mach numbers less than or equal to 0.60. The scatter among the mean corrected results of the bodies of revolution validation cases was within one count of drag on a typical transport aircraft configuration for Mach numbers at or below 0.80 and two counts of drag for Mach numbers at or below 0.90. / Ph. D.

This dissertation traces three ethical dimensions, or values, of weather warnings in the National Weather Service (NWS): an ethic of accuracy, and ethic of care, and an ethic of resilience. Each appear in forecaster work but are not equally visible in the identity of a forecaster as scientific expert. Thus, I propose that the NWS should consider rethinking its science through its relationship to multiple publics, creating what Sandra Harding calls "strong objectivity." To this end, I offer the concept of empathic accuracy as an ethic that reflects the interrelatedness of precision and care that already attend to forecasting work. First, I offer a genealogy of the ethic of accuracy as forecasters see it. Beginning in the 1960s, operational meteorologists mounted an ethic of accuracy through the "man-machine mix," a concept that pointed to an identity of the forecasting scientist that required a demarcation between humans and technologies. It is continually troubled by the growing power of computer models to make predictions. Second, I provide an ethnographic account of the concern expressed by forecasters for their publics. I do so to demonstrate how an ethic of care exists alongside accuracy in their forecasting science, especially during times of crisis. I recreate the concern for others that their labor performs. It is an account that values emotion and is sensitive to context, showing what Virginia Held calls "the self-and-other together" that partially constitutes a forecaster identity. Third, I critique the NWS Weather Ready Nation Roadmap and its emphasis on developing in the public an ethic of resilience. I argue that, as currently framed, this ethic and its instantiation in the initiative Impact Based Decision Support Services narrowly defines community to such an extent that it disappears the public. However, it also reveals other valences of resilience that have the potential to open up a space for an empathetic accuracy. Finally, I close with a co-authored article that explores my own commitment to an ethic of relationality in disaster work and the compromises that create tension in me as a scholar and critical participant in the weather community. / Ph. D.

Force feedback during teleoperation and in Virtual Reality (VR) environments is becoming increasingly common. We are interested in understanding the impact of motion on the directional accuracy of force perception, as observed in a VR environment. We used a custom force-feedback system that pulled a handle with a force of 1.87N at various angles in front of N=14 subjects. The virtual environment showed a curved wall, which corresponded to the locations from which the force could physically originate. Subjects selected where they perceived the force to originate from with a virtual laser pointer and by orienting their head. We compared several conditions: the subject held the handle still; the subject moved the handle back and forth toward the center of the wall; the subject moved the handle back and forth across their body; and the subject moved the handle back and forth toward where they thought the force was originating. Subjects were able to localize the force with an average accuracy of 1-10 degrees depending on the force's location, which is better than previous studies. All conditions had similiar accuracies. Subjects had the best precision when they followed the force as compared to either of the other conditions with movement. / Master of Science / In recent years, robots combined with teleoperation, operating in a remote safe environment, has become a popular choice for replacing human workers in dangerous environments. Visual feedback and a sense of touch and motion, are two of the most common feedback modalities. Thus, Virtual Reality (VR) and force rendering are two main ways of conveying information to the operator during teleoperation.\newline Previous studies have investigated the effects of force feedback on the fingers, wrist, and arms but with limited movements and joint combinations. In this paper, we answered the question of how the planar arm movement impacts the force-directional perception accuracy by using a Virtual Reality (VR) system. To put in other words, we want to find out how accurate and precise a robot operator can feel the physical world through joysticks. If they are asked to do this many times in a row, how repeatable are their guesses? To study this, We asked subjects holding a handle made out of PVC pipe with a position sensor on it. The handle was attached to a motor, which pulled the handle away from the subjects during the experiment trial. The experiment consisted of four different conditions, which studied both stationary, when subjects holding the handle stationary and resist the pull by our motor, and movement, when subjects moving the handle in a certain direction while the handle was pulled by our motor. In each trial, subjects were first asked to resist the force according to the experiment condition, then use a laser pointer and head to both point and look at where they think the motor was pulling the handle from. Because of the use of the VR environment and position sensor, subjects reported their guesses intuitively by pointing and looking at, which eliminated the potential of misreporting guesses. The result of this study is important for designing an effective force feedback system for teleoperation. With this information, a force feedback system in a VR environment could be altered to convey information to a user more accurately, for example to correct any biases that the user may have in where they expect forces to originate.\newline Our results show that arm movements enhanced the force feedback precision without sacrificing the accuracy. Arm movements also improved the subjects' confidence level in how well they thought they could localize a force. The results also suggest that pointing with the head is significantly more precise compared with the hand. Such results can be used to implement a more effective force feedback system combined with a VR environment. Finally, our data also shows that hand had an opposite accuracy pattern compared with the head. Future works are needed to explain this opposite accuracy pattern.