The overall objective of this thesis was to predict, model and measure low frequency acoustic backscatter from the sea surface zone (SSZ). In particular, the objectives were fourfold: to relate the acoustic backscatter Doppler spectrum to the directional waveheight spectrum (DWS) through a perturbation analysis; to develop instrumentation suitable for measuring the properties of acoustic backscatter from the SSZ; to design and implement signal processing hardware and software to process raw data from the instrument; and to deploy the instrument and make measurements to test the validity of the predictions of the theoretical development. A theoretical framework was developed to enable a test of the acoustic analogue of the Coastal Ocean Dynamics Applications Radar (CODAR) technique, using beamforming techniques to simulate the CODAR antennas. Expressions relating the CODAR antenna outputs to the output of an array of omnidirectional acoustic point sensors were developed, and mathematical algorithms and techniques were derived to extract information about the DWS of surface gravity waves from acoustic Doppler backscatter measurements with the array. Models were developed and implemented, showing the expected form of the power spectral density of the acoustic Doppler backscatter seen by single omnidirectional receivers, and the expected form of data products of the beamformed array. An acoustic instrument — the Upward-Looking Sonar Array System (ULSAS) — was developed for stand-alone, remotely controlled operation in both bottom-situated and deep-water, surface-tethered configurations. This device can collect and store large quantities of acoustic data from a multi-element array, under the control of a distant operator over a radio link. The bottom-situated version was deployed in the coastal waters of British Columbia, and the deep water version was deployed in the recent Surface Wave Processes (SWAPP) experiment. A preliminary test of the acoustic CODAR technique was made, yielding information consistent with the known wind and wave field. The form of the non-directional part of the extracted DWS followed approximately the expected k⁻⁴ shape for k values above saturation. Beamforming results using frequency-domain data show that the Doppler-shifted acoustic backscatter is directional in nature. These are the first results of this kind to be reported. The deep-water version of ULSAS was tested for the first time during the SWAPP cruise. In spite of a problem limiting the power output of the projector, estimates of the surface scattering strength parameter over angles of incidence less than 45° were made, showing some surprising departures from the Chapman-Harris empirical formula for S₅ , and interesting angular structure. Measurements of the ambient noise field were also made under calm conditions and during 14 kt winds. / Science, Faculty of / Earth, Ocean and Atmospheric Sciences, Department of / Graduate

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No description available.

With the advent of smaller satellites, along with the need for less than 0.1 μN precision attitude control for interferometry and imaging missions, finer micro- to sub-micro- thrusters have become an area of high interest. As thrusters are developed and ground-tested, it is necessary to evaluate their thrust performance on-orbit. On-orbit measurements offer actual thrust performance in mission conditions, free from ground facility vibrations and miniaturization restraints, and allow a thruster system to achieve a NASA Technology Readiness Level (TRL) of 7-8. A review is conducted of existing and proposed ground and on-orbit thrust measurement techniques. Experimental gaps and complementary methods are examined along with the current thrust resolution limits. A novel fusion technique combining attitude determination, torsional balance, and filtering techniques is proposed to increase resolution beyond current on-orbit minimums, 4μN, via a dedicated sub-μN on-orbit thrust measurement mission. A simulated case study in the application of this measurement technique to a theoretical Casimir-thruster-equipped, 10-7-10-13 N, smallsat mission is explored. A detailed error analysis is conducted, and the technique is found to be analytically viable for greater than or equal to 10-7 N on a 1U nanosat equipped with sun sensor and three-axis gyroscope, as well as physically viable at a TRL 7-9 level. Recommended next steps are modification of the post-processing technique to decrease gyroscope noise and mass restrictions or exploration of suggested alternate methods, including orbit estimation, direct force sensing, and formation flying.

Organizational justice has been the source of a great deal of recent research attention and has consequently been linked to a number of organizationally-relevant constructs, including organizational citizenship behaviors (Moorman, 1991), employee theft (Greenberg, 1990a), organizational commitment (Tyler, 1991), turnover (Dailey & Kirk, 1992) and job performance (Gilliland, 1994). However, researchers' ability to integrate findings from these diverse contexts is currently limited by the absence of a standardized operationalization of the justice construct. To compound this problem, little research has investigated the psychometric properties of existing organizational justice measures. For example, no research has empirically examined the dimensionality or the suggested context-sensitivity of this construct (cf., Cropanzano & Greenberg, 1997). Therefore, the purposes of the current study were to evaluate the psychometric properties of justice and to attempt to develop a global measure that could be applied across contexts. Study 1 involved three phases (1) screening a set of organizational justice items, (2) investigating the dimensionality of organizational justice and (3) examining justice for evidence of measurement stability. The set of items used in the current study was primarily collected from published research by Hauenstein, McGonigle and Flinder (1997). A set of 48 items with acceptable psychometric characteristics was identified. Phase 2 investigated the dimensionality of these items. Results indicated that none of the four a priori models of organizational justice dimensionality could adequately account for the dimensionality of these items. However, three alternative models were discovered. The first model includes the four dimensions suggested by Greenberg (1993b) in addition to a general organizational justice factor while the second model includes only justice and injustice factors in addition to the original organizational justice factor. Finally, the results of an exploratory factor analysis suggested three factors: Systemic Justice; Distributive Injustice; and Distributive Justice. Phase 3 then investigated the stability of this solution across subgroups while Study 2 compared exploratory factor structures across two work contexts. Results demonstrated some differences at both item- and construct-level in organizational justice across levels of job satisfaction and work experience. Further, some factorial instability across work contexts (e.g., selection, performance appraisal) was also observed. As a result, it was concluded that developing a global measure of organizational justice is difficult given the demonstrated context-sensitivity of the construct. Instead, a series of guidelines for developing future measures of organizational justice is proposed. / Ph. D.

In the basic understanding of measurement, students are expected to be able to subdivide a given whole into a unit and then change the position of that unit along the entire length of the whole. These basic operations of subdivision and change of position are related to the more formal operations of partitioning and iterating. In the context of fractions, partitioning and iterating play a fundamental role in understanding fractions as measures, where students are expected to partition a whole into an iterable unit. In the context of angle measurement, students are expected to measure angles as a fractional amount of a full rotation or a circle, by partitioning the circle into a unit angle and then iterating that unit angle to find the measure of the given angle. Despite this link between measurement, fractions, and angles, research suggests that there is a disconnect between students' concepts of measurement and geometry concepts, including angle and angle measurement. Therefore, one area of study that might help us understand this disconnection would be to investigate the relationship between students' concepts of measurement and their concepts of angle measurement. This current study documents sixth, seventh, and eighth grade students' measurement schemes for fractions and their quantifications of angularity, and then investigates the relationship between them. This research is guided by the following question: What is the relationship between middle school students' measurement schemes for fractions and their quantifications of angularity? Results indicate that the majority of students involved in this study do not possess a measurement concept of fractions nor a measurement concept of angularity. However, these results demonstrate that there is a relationship between students' measurement schemes for fractions and their quantifications of angularity. It is concluded that students who construct more sophisticated fraction schemes tend to construct more sophisticated quantifications of angularity. / Doctor of Philosophy / Although the concepts of measurement, fractions, and angle measurement are related, research suggests that there is a disconnect between students' concepts of measurement and geometry concepts, including angle and angle measurement. Therefore, one area of study that might help us understand this disconnection would be to investigate the relationship between students' concepts of measurement and their concepts of angle measurement. This current study documents sixth, seventh, and eighth grade students' understandings of measurement, as indicated by their fraction schemes, and angle measurement, as indicated by how they quantify angularity or the openness of an angle. This study then investigates the relationship between them. This research is guided by the following question: What is the relationship between middle school students' measurement schemes for fractions and their quantifications of angularity? Results indicate that the majority of students involved in this study do not possess a measurement concept of fractions nor a measurement concept of angularity. However, these results demonstrate that there is a relationship between students' measurement schemes for fractions and their quantifications of angularity. It is concluded that students who construct more sophisticated fraction schemes tend to construct more sophisticated quantifications of angularity.

Digitized by Kansas Correctional Industries

Digitized by Kansas State University Libraries

Call number: LD2668 .T4 1951 D6 / Master of Science

International Telemetering Conference Proceedings / October 18-21, 2004 / Town & Country Resort, San Diego, California / A flexible system has been designed to accurately measure and average the outgoing laser energy of a micro-pulse LIDAR unit (MPL). This system incorporates specifically designed analog measurement circuitry interfaced with a microcontroller, allowing researchers to manage experiments from a personal computer. The final system produces a linearly proportional response between an incident laser energy input and the analog and digital circuitry’s output, accurate to within 0.1%. Custom designed algorithms allow the system to average the energy measured in a series of pulses. Each series can range on the order of tens of thousands of pulses.