Thesis (Ph. D.)--University of Texas at Austin, 2002. / Vita. Includes bibliographical references. Available also from UMI Company.

Thesis (M.S. in Electrical Engineering)--Naval Postgraduate School, September 2003. / Thesis advisor(s): Xiaoping Yun, Fotis Papoulias. Includes bibliographical references (p. 61-62). Also available online.

The twin Gravity Recovery and Climate Experiment (GRACE) satellites were successfully launched on March 17, 2002. The mission goal is to make significant improvement in current measurements of the Earth’s gravity field. The satellites are linked by a K-band ranging system, which measures the range change due to the gravitational and non-gravitational accelerations. The non-gravitational accelerations can be obtained by transforming the accelerometer measurements into the inertial frame of reference based on the star camera observations, and will be used to separate gravitational effects in the range changes. However, the accelerometer’s proof mass offset from the center of mass of the spacecraft must be minimized and the misalignment between star camera frame and accelerometer frame must be known accurately in order to reduce the accelerometer data error. In addition, the phase center of the K-band horn must be known to make antenna offset corrections to the range and range change data. The objective of the center of mass calibration is to determine the proof mass offset, and then, to use the center of mass trim assembly mechanism to eliminate this offset. The main purpose of the K-band ranging system calibration is to determine the phase center of the K-band antenna, which will be used to adjust the satellite attitude orientations and make the antenna offset corrections to the K-band ranging system phase measurements. Furthermore, this calibration allows the misalignment between star camera frame and accelerometer frame to be determined. The calibration maneuvers have been designed for the real mission. Estimation algorithms have been developed and complete simulations have been performed. Finally, the real calibration data have been processed. Analysis shows that the proof mass offset has been determined better than the requirement value of 0.1 mm and trimmed well below this value. The boresight error of the K-band horn’s phase center has been determined better than 0.3 mrad and the resultant antenna offset correction error of range and range rate will be much less than the system resolution (10[mu]m ,1[mu]m/ s) and the frame misalignment parameters have been determined better than (0.04o ,1[delta] ) . Overall, the goal of calibrations has been successfully achieved. / text

ITC/USA 2013 Conference Proceedings / The Forty-Ninth Annual International Telemetering Conference and Technical Exhibition / October 21-24, 2013 / Bally's Hotel & Convention Center, Las Vegas, NV / In the wake of sequestration, Test and Evaluation (T&E) groups across the U.S. are quickly learning to make do with less. For Department of Defense ranges and test facility bases in particular, the timing of sequestration could not be worse. Aging optical tracking systems are in dire need of replacement. What's more, the increasingly challenging missions of today require advanced technology, flexibility, and agility to support an ever-widening spectrum of scenarios, including short-range (0 − 5 km) imaging of launch events, long-range (50 km+) imaging of debris fields, directed energy testing, high-speed tracking, and look-down coverage of ground test scenarios, to name just a few. There is a pressing need for optical tracking systems that can be operated on a limited budget with minimal resources, staff, and maintenance, while simultaneously increasing throughput and data quality. Here we present a mathematical error model to predict system performance. We compare model predictions to site-acceptance test results collected from a pair of multi-band optical tracking systems (MBOTS) fielded at White Sands Missile Range. A radar serves as a point of reference to gauge system results. The calibration data and the triangulation solutions obtained during testing provide a characterization of system performance. The results suggest that the optical tracking system error model adequately predicts system performance, thereby supporting pre-mission analysis and conserving scarce resources for innovation and development of robust solutions. Along the way, we illustrate some methods of time-space-position information (TSPI) data analysis, define metrics for assessing system accuracy, and enumerate error sources impacting measurements. We conclude by describing technical challenges ahead and identifying a path forward.

ITC/USA 2012 Conference Proceedings / The Forty-Eighth Annual International Telemetering Conference and Technical Exhibition / October 22-25, 2012 / Town and Country Resort & Convention Center, San Diego, California / The execution of experimental Flight Test Campaign (FTC) provides all information required for the aircraft operation and certification. Nowadays all information gathered during a FTC is provided by the Flight Test Instrumentation System (FTI) that is basically a measurement system. Typically for all FTI parameters, the estimation of the calibration coefficients that minimizes most of systematic errors and its associated uncertainty is carried out by a Static Calibration Process. To execute this task the Brazilian Institute of Research and Flight Test (Instituto de Pesquisa e Ensaios em Voo - IPEV) developed the Sistema de Automação do Laboratório de Ensaios em Voo (SALEV©) which is fully compliant with the calibration and uncertainty expression standards. For some parameters (i.e. Static Pressure) the sensor installation particularities (i.e. Pressure tapping) introduces low pass filtering characteristics into the measurement chain. In this case the measurement accuracy will be jeopardized when executing high-dynamic test points (i.e. Spin Tests). To overcome this issue the IPEV research and development group introduced a dynamic calibration process for flight test parameters that requires the knowledge of the actual Transfer Function (TF). The problem now is to simulate an impulsive input for the TF characterization which is too complex. To solve this issue a new calibration procedure was developed and evaluated for the determination of the FTI dynamic response. SALEV© was used to simulate a step input instead of an impulse. Then filtered and unfiltered data was properly compared for the determination of the TF. Preliminary test results show satisfactory performance.

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As techniques for manufacturing and metrology advance, optical systems are being designed with more complexity than ever before. Given these prescriptions, alignment and calibration can be a limiting factor in their final performance. Computer generated holograms (CGHs) have several unique properties that make them powerful tools for meeting these demanding tolerances. This work will present three novel methods for alignment and calibration of optical systems using computer generated holograms. Alignment methods using CGHs require that the optical wavefront created by the CGH be related to a mechanical datum to locate it space. An overview of existing methods is provided as background, then two new alignment methods are discussed in detail. In the first method, the CGH contact Ball Alignment Tool (CBAT) is used to align a ball or sphere mounted retroreflector (SMR) to a Fresnel zone plate pattern with micron level accuracy. The ball is bonded directly onto the CGH substrate and provides permanent, accurate registration between the optical wavefront and a mechanical reference to locate the CGH in space. A prototype CBAT was built and used to align and bond an SMR to a CGH. In the second method, CGH references are used to align axi-symmetric optics in four degrees of freedom with low uncertainty and real time feedback. The CGHs create simultaneous 3D optical references where the zero order reflection sets tilt and the first diffracted order sets centration. The flexibility of the CGH design can be used to accommodate a wide variety of optical systems and maximize sensitivity to misalignments. A 2-CGH prototype system was aligned multiplied times and the alignment uncertainty was quantified and compared to an error model. Finally, an enhanced calibration method is presented. It uses multiple perturbed measurements of a master sphere to improve the calibration of CGH-based Fizeau interferometers ultimately measuring aspheric test surfaces. The improvement in the calibration is a function of the interferometer error and the aspheric departure of the desired test surface. This calibration is most effective at reducing coma and trefoil from figure error or misalignments of the interferometer components. The enhanced calibration can reduce overall measurement uncertainty or allow the budgeted error contribution from another source to be increased. A single set of sphere measurements can be used to calculate calibration maps for closely related aspheres, including segmented primary mirrors for telescopes. A parametric model is developed and compared to the simulated calibration of a case study interferometer.

Hyper-spectral (HS) sensors are the instruments of choice for remote sensing applications involving environmental monitoring, littoral survey, and military assessment. Accurate band-to-band sensor radiometric calibration is critical for successful data mining of such HS spectral sets. Current calibration is often performed with methods not necessarily developed for HS applications. This work describes two advances which facilitate laboratory source calibrations. First, an analytical solution to the attenuation of flux within an integrating sphere, the best laboratory source of non-directional radiance for numerous radiometric applications, is given. Relative component attenuations due to integrating sphere coating, exit port escape, and atmospheric absorption are derived employing a geometrical PDF of summed probabilities. Equations providing the attenuation ratios and mean number of reflections for the three outcomes are obtained, yielding the three partial mean pathlengths and variances of all quantities. This work then describes an approach allowing accurate radiometric calibration of HS sensor bands using well-characterized and stable multi-spectral transfer radiometers. The resulting high-quality calibration enables the best representation of the truth spectral signature of the imaged scene. In order to obtain the best calibration with the least instrument complexity and expense, it is critical that the radiometer samples the source with the fewest samples at those optimal wavelengths which predict that source with the highest accuracy. The optimal source-specific bands are determined efficiently by application of the Direct Search methodology described here. Using the minimal selection of multi-spectral radiometer measurements obtained from the optimized transfer radiometer bands, one can obtain a complete and accurate calibration set for the continuum of calibration coefficients required for a robust HS application. Degradation of the prediction is documented for several typical error sources encountered with calibration, thereby defining limitations on the usefulness of the optimization approach.

Calibrated estimators of the population total and of the ratio of two totals. In the e are presented and analysed. Calibrated estimators – estimators in which auxiliary information is used in order to get more accurate estimates of the parameters. Different distance measures were used to construct calibrated estimators using the Lagrange multiplier method. It is known, that in some cases calibrated estimators coincide with the ratio estimators, which are more accurate if the study variable is well correlated with the known auxiliary variable. Three estimators of totals and three estimators of a ratio are presented in the work as well as their approximate variances and variance estimators. The approximate variances were calculated using Taylor linearization technique. The experimental comparison of the considered estimators is presented when correlation between study variable and known auxiliary variable is 0.8, 0.6, 0.4, 0.2. The computer program for the calculation is made using the Language of Technical Computing MATLAB.

With the development of various derivative instruments and index products, commodities have become a distinct asset class which can offer enhanced diversification benefits to the traditional asset allocation of stocks and bonds. In this thesis, we begin by discussing some of the key properties of commodity markets which distinguish them from bond and stock markets. Then, we consider the informational role of commodity futures markets. Since commodity prices exhibit mean-reverting behaviour, we will also review several mean-reversion models which are commonly used to capture and describe the dynamics of commodity prices. In Chapter 4, we focus on discussing a two-factor mean-reverting model proposed by Hikspoors and Jaimungal, as a means of providing additional degree of randomness to the long-run mean level. They have also suggested a method to extract the implied market prices of risk, after estimating both the risk-neutral and real-world parameters from the calibration procedure. Given the usefulness of this model, we are motivated to investigate the robustness of this calibration process by applying the methodology to simulated data. The capability to produce stable and accurate parameter estimates will be assessed by selecting various initial guesses for the optimization process. Our results show that the calibration method had a lot of difficulties in estimating the volatility and correlation parameters of the model. Moreover, we demonstrate that multiple solutions obtained from the calibration process would lead to model uncertainty in extracting the implied market prices of risk. Finally, by using historical crude oil data from the same time period, we can compare our calibration results with those obtained by Hikspoors and Jaimungal.