International Telemetering Conference Proceedings / October 25-28, 1999 / Riviera Hotel and Convention Center, Las Vegas, Nevada / The Instrumentation and Telemetry Departments at Sandia National Laboratories have been exploring the instrumentation of sealed canisters where the flight application will not tolerate either the presence of a chemical power source or penetration by power supply wires. This paper will describe the application of a low power micro-controller based instrumentation system that uses magnetic coupling for both power and data to support a flight application.

The study of acoustic resonance in fluid-filled piping systems with and without mean flow is important for the nuclear industry. For this industry, it is vital to understand the acoustic resonance in their systems; however, no comprehensive experimental benchmark data or accurate modeling tool exists for predicting such a phenomenon. The main goals of the current research are to create a new experimental data bank for the conditions not tested earlier using the configurations of straight lines and branches, and to evaluate the applicability of the linear wave solution using different damping methods and a computational fluid dynamic (CFD) code to simulate the acoustic resonance in fluid-filled piping systems. In this experimental study, data on resonant frequencies and resonant amplitudes are collected and analyzed for a frequency range of 20–500 Hz for straight and branched tubes by varying their wall thicknesses, materials, and branch configurations at different flow rates and outlet boundary conditions. To be closer to the nuclear industry medium, water is employed in our experiments, contrasting to the fact that most of the available experiments reported were with air at a much lower sonic velocity. I consider here, in particular, measurements at the end of closed branches, upstream, downstream, and at different locations of the main line, as well as the interactions of different sonic velocities along the main pipes. A small diameter is chosen for the branched experiments since the decrease in the width of the main line and the branches has a pronounced effect on the resonant amplitudes due to an increased interaction among the unsteady shear layers forming across the side branches. The experimental results show that there is a strong effect of turbulent flow, wall material, and wall thickness on resonant amplitudes at frequencies above ∼250 Hz. Numerical investigations are performed solving the one-dimensional (1D) linear wave equation with constant and frequency-dependent damping terms and a CFD code. Employing frequency-dependent damping methodologies shows improvement in terms of resonant amplitude prediction over constant volumetric drag method. Comparing the 1D and CFD results shows that the CFD solution yields better predictions. / February 2017

The mesopause region monthly mean winds and semidiurnal tidal amplitudes and phases over Central Europe in the height range between 85-105 km have been measured at Collm Observatory continuously since September 1982. The regular annual cycle of the semidiurnal tidal amplitudes show in all cases maximum values during late August and September. In contrast to that, in autumn 2002 no enhancement of the tidal amplitudes was measured, while the autumn tidal phase transition occurred unusually early. The unexpected behaviour of the semidiurnal tides seems to be connected with a very early autumn transition of the zonal prevailing winds. This suggests that in 2002 the zonal mean winds influence the tidal propagation in a different way than usual. / Die monatlich gemittelten Grundwinde und halbtägigen Gezeiten werden am Collm seit September 1982 im Höhenbereich zwischen 85-105 km gemessen. Der normale Jahresgang der halbtägigen Gezeiten zeigt maximale Amplituden im Winter und vor allem im Spätsommer/Herbst. Dieses Maximum ist im Jahre 2002 nicht zu verzeichnen. Dies ist begleitet von einer ungewöhnlich frühen Phasenänderung von der Sommer- zur Winterposition. Das Verhalten der Gezeiten scheint mit einer sehr frühen Änderung des zonalen Grundwindes vom Sommer- zum Winterregime verbunden zu sein, so dass die Anomalie der mittleren Zirkulation für die Gezeitenanomalie verantwortlich zu sein scheint.

Large-amplitude vibration of thin plates and shells has been critical design issues for many engineering structures. The increasingly more stringent safety requirements and the discovery of new materials with amazingly superior properties have further focused the attention of research on this area. This thesis deals with the vibration problem of rectangular, circular and angle-ply composite plates. This vibration can be triggered by an initial vibration amplitude, or an initial velocity, or both. Four types of boundary conditions including simply supported and clamped combined with in-plane movable/immovable are considered. To solve the differential equation generated from the vibration problem, Lindstedt's perturbation technique and Runge-Kutta method are applied. In previous works, this problem was solved by Lindstedt's Perturbation Technique. This technique can lead to a quick approximate solution. Yet based on mathematical assumptions, the solution will no longer be accurate for large amplitude vibration, especially when a significant amount of imperfection is considered. Thus Runge-Kutta method is introduced to solve this problem numerically. The comparison between both methods has shown the validity of the Lindstedt's Perturbation Technique is generally within half plate thickness. For a structure with a sufficiently large geometric imperfection, the vibration can be represented as a well-known backbone curve transforming from soften-spring to harden-spring. By parameter variation, the effects of imperfection, damping ratio, boundary conditions, wave numbers, young's modulus and a dozen more related properties are studied. Other interesting research results such as the dynamic failure caused by out-of-bound vibration and the change of vibration mode due to damping are also revealed.

The aesthetic response is a multifaceted and subtle behavior that ranges in magnitude from sublime to mundane. Few studies have investigated the more subtle, weak aesthetic responses to mundane scenes. But all aesthetic responses rely upon sensory-perceptual processes, which serve as a crucial first step in contemporary models of the aesthetic response. As such, understanding the roles of perceptual processes in aesthetic responses to the mundane provides insights into all aesthetic responses. Variation in the physical properties of aesthetic objects must cause such responses, but to understand the relationship, such physical properties must be quantified. Then, the mechanism can be determined. Here, I present the theoretical basis and reason for interest in such a test of mundane aesthetic responses in Chapter I. In Chapter II, I present metrics that quantify the physical properties of natural scenes, using computer-generated images that model the complexity of natural scenes to validate these measurement techniques. The methods presented in Chapter II are adapted to analyze the physical properties of natural scenes in Chapter III, extending the analysis to photographs and clarifying the relationship between the properties fractal dimension and spectral scaling decay rate. A behavioral study is presented in Chapter IV that investigates the extent that perceptual responses about complexity serve as an intermediary between aesthetic ratings and the physical properties of the images described in Chapters II and III. Chapter V summarizes the results of these studies and explores future directions. This dissertation includes previously published and unpublished coauthored material.

The standard deviation of surface EMG (EMGσ) is often related to muscle force; the accuracy of EMGσ estimation is valuable for many application areas such as clinical biomechanics, prostheses control and sports medicine. Numerous researchers have developed methods to optimize EMGσ estimation. Whitening the EMG signal has been proved to improve the statistical efficiency of EMGσ estimation, but conventional linear whitening filters fail at low contraction level. An adaptive whitening filter was proposed by Clancy and Farry[14]. This technique has a better performance than prior whitening methods, however, the adaptive whitening filter needs to be calibrated each time electrodes are applied, which increase the complexity of the implementation. We designed a universal whitening filter which can omit most calibration steps for the adaptive whitening filter in future use. We used the ensemble mean of the power spectrum of 512 EMG recordings to form a general shape of a fixed whitening filter that can applied on any EMG signal. The test error on an EMG-torque task based on universal whitening over 512 subjects had a mean error of 4.80% maximum voluntary contraction (MVC) and standard deviation (std) of 2.03% MVC, compared with an original adaptive whitening filter error of 4.84±1.98% MVC. Additionally, the rest contraction modeling hasn’t received enough attention. Existing RMS estimates of EMGσ subtract noise in either the amplitude or power domain. These procedures have never been modeled analytically. We show that power domain noise subtraction is optimal. But rest contractions which are processed using power domain noise subtraction only estimate a zero-valued EMGσ approximately 50% of the time, which is undesirable in prosthesis-control. The prosthesis has a 50% possibility to slowly drift based on the current RMS estimator. We propose a new estimator to improve the zero-amplitude estimation probability during rest. We used 512 rest contraction recordings to validate the probability distribution of rest EMG signal showing that it only has 1.6% difference compared with Gaussian distribution. We also evaluated the percent of zero-valued EMGσ estimates using power domain noise subtraction and our new estimator, matching experimental findings to the theoretic predictions.

The purpose of this study was to determine the effects of task difficulty on the amplitude and latency of the P300 by altering the intensity of the oddball stimulus. A P300 was obtained on 22 adult subjects ranging in age from 21 to 34 years of age (mean = 24 years) with normal hearing. The "frequent stimulus" was a 1000 Hz or 4000 Hz tone burst, gated with a rise and fall time of 10 msec and 20 msec plateau, presented at 75 dBn HL The "oddball stimulus" was a tone burst of the same frequency (1000 Hz or 4000 Hz)presented at 77, 79, or 81 dBn HL. A four-channel recording was made with linked reference electrodes and the following montages:Cz-A1+A2, Pz-A1+A2, and Fz-A1+A2. The fourth channel was used to monitor "eye blink" activity. The investigation tested the null hypothesis that changing the intensity of the oddball stimuli would not result in a significant change in either the amplitude or latency of the P300. Analyses of Variance (ANOVA) indicate that P300 latency and amplitude did not differ significantly by run, stimulus frequency, intensity of the oddball, or montage. Thus the null hypothesis was supported.

This thesis sought to: 1) examine the effect of a number of organism and task constraints on the control of two forms of physiological tremor, namely postural and finger-pinch force tremor; and 2) determine if the expected constraint-related changes in tremor output were associated with alterations in the control strategy utilised by the performer. The organism constraints were age and resistance-training (for both forms of tremor), while the task constraints were visual feedback, target size and limb preference (postural tremor) and mean force, target shape and limb preference (force tremor). The postural (index finger) tremor amplitude of young adults was significantly greater in the augmented vision (AV) than normal vision (NV) conditions and when using the non-preferred than preferred limb. Even greater differences/changes in postural tremor amplitude were observed as a function of aging and training. Older adults had significantly more index finger tremor amplitude than young adults. Regardless, the older adults who completed a six weeks program of unilateral strength- or coordination-training were able to significantly reduce their tremor amplitude. Although the training-related reductions in tremor amplitude were of a greater magnitude for the trained than untrained limb, a significant reduction in the tremor amplitude of the untrained limb was also observed for the coordination-training group. All of these significant differences/changes in tremor amplitude were associated with significant changes in a number of other dependent variables. For example, the task- and age-related increases in tremor amplitude were primarily a result of greater 8-12 Hz tremor power and were associated with increased EMG activity/co-activation of the extensor digitorum (ED) and flexor digitorum superficialis (FDS) muscles and a significant reduction in intra-limb (index finger-hand and forearm-upper arm) coupling. The significant reductions in tremor amplitude observed for the resistance-trained older adults was a result of a significant decline in 8-12 Hz power and were associated with a significant reduction in ED and FDS co-activation. However, no significant change in intra-limb coupling was observed. The overall trends observed in the results for the finger-pinch force tremor experiments were similar to those for postural tremor. Older adults had significantly more finger-pinch force tremor (i.e. force variability and targeting error) than young adults, although older adults who performed six weeks of unilateral strength-training were able to significantly reduce the force variability and targeting error of the trained limb. No significant training-related reduction in force tremor was however observed for the untrained limb. The significant age-related increase in force tremor was a result of greater low frequency (less than 2 Hz) power and was associated with a significant loss of inter-digit force sharing and coupling as well as tactile sensitivity. Interestingly, the training-related decreases in force tremor were not associated with significant changes in any of the frequency, sharing or coupling measures. Collectively, the results of the five experiments contained in this thesis add much to our understanding of postural and force tremor. Results indicated that numerous task and organism constraints can have a substantial effect on the resulting tremor output. Furthermore, the task- and age-related differences in the power spectral, muscle activity and coupling measures suggested that the changes in tremor output were the result of the use of an altered (sub-optimal) control strategy. The age-related increase in postural and force tremor amplitude may therefore reflect not only an overall decline in neuromuscular system function, but also the relative inability of older adults to effectively coordinate the output of numerous degrees of freedom (limb segments). The effect of the aging process on tremor output was somewhat reversible, with the older adults who performed resistance-training significantly improving their control of both postural and force tremor. There was some evidence that resistance-training could produce cross-education effects in older adults, although these were only statistically significant for postural tremor amplitude in the coordination-training group and for wrist flexion strength in the strength-training group. The relative brevity of the training program (6 weeks) and the observable cross-education effects suggest that the reduction in tremor amplitude and increases in strength were primarily a result of neural adaptations. Such findings further support the prescription of resistance-training for improving physical function in older individuals.

The purpose of this study was to investigate the influence of amplitude scaling on bimanual coordination in a circle drawing task. Eleven right-handed subjects traced the perimeter of 5 circles measuring 3, 6, 9, 12, and 15 cm in diameter under the following coordination conditions: (1) both hands move inward together (symmetric coordination pattern), and (2) both hands move counterclockwise together (asymmetric coordination pattern). In a set of self-paced trials, subjects traced each circle separately at a preferred frequency and separately for each coordination pattern. Although subjects matched the required amplitude of the target circles quite well, radial amplitude variability increased with increasing circle diameter. No transitions or movement reversals were observed in the self-paced trials, and the symmetric pattern was more stable than the asymmetric pattern. In a set of amplitude scaling trials, subjects continuously traced the 5 circles from small (3 cm) to big (15 cm) (SB) and from big to small (BS) at two fixed pacing frequencies (1.25 Hz and 1.5 Hz). Observed cycling frequency decreased with increasing circle diameter, and observed radial amplitude was most accurate when tracing the 9 cm diameter circle, with larger than required amplitude when tracing the 3 cm and 6 cm diameter circles, and smaller than required amplitude when tracing the 12 cm and 15 cm diameter circles. Radial amplitude variability also increased with increasing circle diameter in the amplitude scaling trials. The symmetric coordination pattern was more stable than the symmetric coordination pattern. Transitions from the asymmetric to symmetric coordination pattern as well as movement reversals were observed in both scaling directions. No transitions occurred while producing the symmetric pattern in any scaling direction or pacing frequency condition. The results show that amplitude scaling influenced the spatiotemporal aspects of bimanual circle drawing. Moreover, amplitude scaling induced more transitions than previous research that scaled movement frequency as a control parameter in bimanual circle drawing tasks.

This thesis is a study of the validity and application of the on-shell recursion relations within the theory of General Relativity. These relations are also known as the Britto-Cachazo-Feng-Witten (BCFW) relations. They reduce the calculation of a tree-level graviton scattering amplitude into the evaluation of two smaller physical amplitudes and of a propagator. With multiple applications of the recursion relations, amplitudes can be uniquely constructed from fundamental three-graviton amplitudes. The BCFW prescriptions were first applied to gauge theory. We thus provide a self-contained description of their usage in this context. We then generalize the proof of their validity to include gravity. The BCFW recursion relations can then be used to reconstruct the full theory from cubic vertices. We finally describe how these three-graviton vertices can be determined uniquely from Poincare symmetries.