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ITC/USA 2006 Conference Proceedings / The Forty-Second Annual International Telemetering Conference and Technical Exhibition / October 23-26, 2006 / Town and Country Resort & Convention Center, San Diego, California / Network-centric data acquisition and telemetry systems continue to gain momentum and adoption. However, inherent non-deterministic network delays hinder these systems’ suitability for use where high-accuracy timing information is required. The emerging IEEE 1588 standard for time distribution offers the potential for real-time data acquisition system development using cost-effective, standards-based network technologies such as Ethernet and IP multicast. This paper discusses the challenges, realities, lessons, and triumphs experienced using IEEE 1588 in the development and implementation of such a large-scale network-centric data acquisition and telemetry system. IEEE 1588 clears a major hurdle in moving the network-centric buzz from theory to realization.

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International Telemetering Conference Proceedings / October 26-29, 1992 / Town and Country Hotel and Convention Center, San Diego, California / The Air Force Flight Test Center (AFFTC) at Edwards, California has installed the Edwards Digital Switch (EDS). The EDS is a DS-1 switch capable of switching voice, encrypted voice, and Time Space Position Information (TSPI) data. Communicating encrypted voice and TSPI data reliably from the EDS to any other communication system requires the two systems operate using the same frequency reference. The need to communicate with other test ranges and over commercially leased lines using the EDS requires synchronization to a standard frequency source. The current synchronization method used at the AFFTC is unacceptable for the EDS. A hierarchal system of synchronization networking will be implemented to provide a common reference to each of the systems interfacing the EDS. The Master Timing Station (MTS), which provides synchronization reference to most of the AFFTC resources, is aging and must be upgraded. The upgrade of the MTS and the restructuring of the synchronization signal distribution will be completed simultaneously. Traceability to the United States Naval Observatory (USNO) and the National Bureau of Standards (NBS) is required to provide the necessary synchronization to allow the EDS to interface reliably with other systems. The Global Positioning System (GPS) is being considered as the primary source for frequency calibration traceable to the USNO and NBS.

Single-frequency Global Positioning System (GPS) receivers do not accurately compensate for the ionospheric delays imposed upon GPS signals. This can lead to significant errors and single-frequency systems rely upon models to compensate. This investigation applies 4D (four-dimensional) ionospheric tomography to GPS timing for the first time. The tomographic algorithm, MIDAS (Multi-Instrument Data Analysis System), is used to correct for the ionospheric delay and the results are compared to existing single and dual-frequency techniques. Days during the solar maximum years 2002, 2003 and 2004 have been chosen to display results when the ionospheric delays are large and variable. Maps of the ionospheric electron density, across Europe, are produced by using data collected from a fixed network of dual-frequency GPS receivers. Results that improve upon the use of existing ionospheric models are achieved for fixed (static) and mobile (moving) GPS receiver scenarios. The effects of excluding all of the GPS satellites below various elevation masks, ranging from 5° to 40°, on timing solutions for fixed and mobile situations are also presented. The greatest timing accuracies when using the fixed GPS receiver technique are obtained by using the highest mask. The mobile GPS timing solutions are most accurate when satellites at lower elevations continue to be included. Furthermore, timing comparisons are made across baselines up to ~4000 km and the ionospheric errors are shown to increase with increasing baseline. GPS time transfer is then investigated and MIDAS is shown to improve the time transfer stabilities of a single-frequency GPS system. The results are comparable to the dual-frequency time transfer after ~2 hours averaging time. Overall, the MIDAS technique provides the most accurate and most stable results (comparable to dual-frequency) for a single-frequency based GPS system. Ionospheric corrections (via MIDAS) may be broadcast to users nationally or via the internet for example, opening up the possibility of improving the accuracy and stability of single-frequency GPS systems in real-time.

In the current gas turbine market, the traditional design-test-redesign loop is not a viable solution to deploy new products within short timeframes. Hence, to keep the amount of testing to an absolute minimum, theoretical simulation tools like Finite Element Modelling (FEM) have become a driving force in the design of blades to predict the dynamic behaviour of compressor and turbine assemblies in high-speed and unsteady flows. The predictions from these simulation tools need to be supported and validated by measurements. For the past five years, Rolls-Royce Blade Tip Timing (BTT) technology has been replacing rotating Strain Gauge systems to measure the vibration of compressor blades, reducing development times and costs of new aero engine programmes. The overall aim of the present thesis is to progress the BTT technology to be applied to aero engine turbine modules. To this end, the two main objectives of this project are: i. To improve the current validated Rolls-Royce BTT extraction techniques, through the development of novel algorithms for single/multiple asynchronous and responses. ii. To validate the improved extraction using simulated and real engine test data in order to bring the Turbine BTT technology to a Rolls-Royce Technology Readiness Level (TRL) of 4 (i.e. component and/or partial system validation in laboratory environment). The methodology adopted for the development of the novel algorithms is entirely based on matrix algebra and makes extensive use of singular value decomposition as a means for assessing the degree optimisation achieved through various novel manipulations of the input (probe) raw data. The principle contributions of this thesis are threefold: i. The development of new BTT matrix-based models for single/multiple non-integral and integral engine order responses that removed certain pre-processing assumptions required by the current method. ii. The development of BTT technology to operate under the constraint of having equally spaced probes, which is unavoidable in turbines and renders current BTT methods unusable for turbine applications. iii. The development of methods for extracting measurement uncertainty and signal to noise ratios that are based solely on the raw data, without reliance on simulated reference data. Following the verification and validation of the new processing algorithms against simulated data and against validated software with numerous examples of actual engine test data, a Rolls-Royce's Research & Technology (R&T) Critical Capability Acquisition and Capability Readiness (CCAR) review has accredited the novel techniques with a TRL of 4.

Success in baseball batting is fundamental to the sport, however it remains one of, if not the most, challenging skills in sports to master. Batters utilize the kinetic chain to transfer energy from the lower body to the upper body to the bat, hoping to impart the maximum amount of energy into the ball. Scientists and coaches have researched the swing and developed theories on the keys for successful batting, but most of this research has been inadequate in attempting to fully describe the biomechanics of batting. The purposes of this study were to improve upon the methodology of previous researchers, provide a full biomechanical description of the swing, and compare swings against pitches thrown to different locations and at different speeds. AA-level Minor League Baseball players (n=43) took extended rounds of batting practice in an indoor laboratory against a pitcher throwing a mixture of fastballs and changeups. An eight camera motion analysis system and two force plates recording at 300 Hz captured the biomechanical data. The swing was divided into six phases (stance, stride, coiling, swing initiation, swing acceleration, and follow-through) by five key events (lead foot off, lead foot down, weight shift commitment, maximum front foot vertical ground reaction force, and bat-ball contact). Twenty-eight kinematic measurements and six ground reaction force measurements were computed based on the marker and force plate data, and all were assessed throughout the phases. First, a comprehensive description of a composite of the batters’ swings against fastballs “down the middle” was provided. Second, successful swings against fastballs thrown to one of five pitch locations (HIGH IN, HIGH OUT, LOW IN, LOW OUT, MIDDLE) were compared in terms of selected kinematics at the instant of bat-ball contact, timing and magnitude of peak kinematic velocities, and timing and magnitude of peak ground reaction forces. Third, these variables were once again compared for swings against fastballs and changeups. A large number of biomechanical differences were seen among the swings against various pitch locations. More fully rotated positions, particularly of the pelvis and bat were critical to the batters’ successes on inside pitches while less rotated positions keyed successes against outside pitches. The trail and lead arms worked together as part of a closed chain to drive the hand path. Successful swings had the trail elbow extended more for HIGH IN and flexed more for LOW OUT, though batters often struggled to execute this movement properly. A distinct pattern among successful swings against fastballs, successful swings against changeups, and unsuccessful swings against changeups was witnessed; namely a progressive delay in which the batter prematurely initiated the events of the kinetic chain, especially when unsuccessful in hitting a changeup. It was believed that this study was much more effective in capturing the essence of baseball batting than previous scientific works. Some recommendations to batting coaches would be to get batters to take a consistent approach in the early phases of every swing (particularly for the lower body), identify both pitch type and location as early as possible, use the rotation of the pelvis to propagate the energy transfer of the kinetic chain from the group to the upper body, and use the pelvis, and subsequently, the upper body, to orient the trunk and hands to an optimal position to drive the ball to the desired field. Limitations of the current study and ideas for future work were also presented to better interpret the findings of this research and further connect science and sport.