Thesis (Ph.D.)--University of Delaware, 2005. / Principal faculty advisor: Dennis R. Mertz, Dept. of Civil & Environmental Engineering. Includes bibliographical references.

This study sought to discover the relationship of torque to the academic performance and other variables of children from five to eight years old. Torque was defined as the production of clockwise circles during a writing task. The phenomenon was first reported by Theodore Blau (1977) who proposed that children who torqued past a certain age were predisposed to problems both academic and behavioural. To measure the torquing propensities of children, Blau developed a Torque Test which had children produce six circles around X's (⊗), three with the preferred hand and three with the non-preferred hand. The present study used the preferred writing hand only and two torque tests, the Circling Directionality Test developed by the researcher using an embedded task to detect torquing and a modified form of Blau's Torque Test. Variables of academic achievement, age, sex, point of circle commencement, laterality, neuromuscular motor, control , test comparisons, and circling directionality were analysed. The population for the study consisted of 300 regular classroom children ages five to eight. Seventy-five children per grade were randomly selected by age from grade levels K-3. Significant relationships between torquing and low academic achievement were only found for the eight year old group who also had a higher incidence of left-handedness and crossed hand/foot laterality. Significantly more boys torqued than girls. As well, those who torqued in most instances commenced their circles at the bottom. Predictably significant relationships were found for hand and foot, but only left-handedness was significantly related to torque. No significant relationships could be found for measures of eyedness. Both tests used to measure torque were equally effective. The rapidity of circle construction did not alter the pattern of torquing in the children. There was a significant relationship between age and torquing with over 50% of the five year olds torquing with the preferred hand; by age eight this incidence had been reduced to 8% of the population. Torquing was then seen as a developmental trait found in a large percentage of five and six year olds but by age eight it was indicative of academic school difficulties. Recommendations for further study of the torquing phenomenon were made. / Education, Faculty of / Graduate

No description available.

Condition monitoring of rotating shafts is gaining importance in industry due to the need to increase machine reliability and decrease the possible loss of production due to machine breakdown. In this work, the use of vibration signals for the detection of a crack within a shaft was investigated. The research involved the measurement of vibration signals during laboratory tests on a long rotating shaft rig. The focus of the experimental work was on the effect of cracks on the dynamics and the initiation and growth of cracks in the shaft. Measurements were taken from the shaft system both with simulated cracks (notches) cut at 45° and 90° to the shaft axis and with real propagating cracks initiated by a pre-crack cut. All defects were located at the mid- point along the shaft. The vibration responses and stresses were measured for different depths of crack. The vibration responses of the three different defects were compared using PSDs of the data to identify the change in position and magnitude of the peaks in the spectrum under each defect. Experiments to study the effect of defect depth at different shaft rotation speeds were also carried out. Finally, a shaft with a breathing crack (continuously opening and closing as the shaft rotates) was also studied experimentally, with the crack growing under normal steady state operating conditions. After completing the experiment work, the shaft was broken and the type of fracture studied. The results for both simulated and actual crack growth showed that vibration frequencies decreased as a crack progressed, indicating the possibility of using the vibration signal for crack detection. A significant relationship was found between the stage of crack growth and the vibration results. A finite element (FE) model was constructed to explore the relationship between the natural frequencies and crack depth and position along the shaft and to explain and validate the results of the experimental work. The FE model showed similar trends to the experimental results and also allowed the effect of different crack positions to be explored. The PSD data was fed into an artificial neural network after a feature extraction procedure was applied to significantly reduce the quantity of data whilst at the same time retaining the salient information. Such an approach results in a considerably reduced training time for the network due to the reduced complexity. The proposed scheme was shown to successfully identify the different defect levels. This method greatly enhances the capacity of an automated diagnostic process by linking increased capability in signal analysis to the predictive capability of the artificial neural network.

Thesis (Sc.D.)--Massachusetts Institute of Technology, Dept. of Aeronautics and Astronautics, 1981. / MICROFICHE COPY AVAILABLE IN ARCHIVES AND AERO. / Includes bibliographical references. / by Olivier Andre Bauchau. / Sc.D.

Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Aeronautics and Astronautics, 1982. / MICROFICHE COPY AVAILABLE IN ARCHIVES AND AERO. / Includes bibliographical references. / by Anthony Henry James Eastland. / M.S.

Fung, Shu Hong = 量子點內自旋弱量度的散粒噪聲相關理論 / 馮書航. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2008. / Includes bibliographical references (p. 80-85). / Abstracts in English and Chinese. / Fung, Shu Hong = Liang zi dian nei zi xuan ruo liang du de san li zao sheng xiang guan li lun / Feng Shuhang. / Chapter 1 --- Introduction --- p.1 / Chapter 2 --- Review on measurement theory --- p.5 / Chapter 2.1 --- Weak measurement --- p.5 / Chapter 2.2 --- POVM formalism --- p.7 / Chapter 2.3 --- Noise spectroscopy --- p.8 / Chapter 3 --- Review on spin decoherence --- p.11 / Chapter 3.1 --- Longitudinal relaxation --- p.12 / Chapter 3.2 --- Transverse relaxation --- p.12 / Chapter 3.3 --- Inhomogeneous broadening --- p.13 / Chapter 3.4 --- Typical relaxation timescales --- p.14 / Chapter 4 --- Proof-of-principle setup --- p.15 / Chapter 4.1 --- Faraday rotation --- p.15 / Chapter 4.2 --- Polarization beam splitter --- p.17 / Chapter 4.3 --- Quantum state of the system --- p.19 / Chapter 5 --- Weak measurement on the spin --- p.22 / Chapter 5.1 --- POVM of measurement --- p.22 / Chapter 5.2 --- POVM of dephasing --- p.25 / Chapter 5.3 --- Interval distribution operator --- p.26 / Chapter 5.4 --- Interval distribution function without dephasing --- p.27 / Chapter 5.5 --- Second order correlation function without dephasing --- p.31 / Chapter 5.6 --- Interval distribution function with dephasing --- p.34 / Chapter 5.7 --- Second order correlation function with dephasing --- p.40 / Chapter 5.8 --- Effect of inhomogeneous broadening on g(2)(t) --- p.42 / Chapter 5.9 --- Third order correlation function --- p.43 / Chapter 5.10 --- Monte Carlo simulation --- p.44 / Chapter 5.11 --- Results and discussion --- p.46 / Chapter 5.11.1 --- Characteristics and implications of g(2)(t) --- p.46 / Chapter 5.11.2 --- "Characteristics and implications of g(3)(t1,t2)" --- p.47 / Chapter 6 --- Interval distribution function with random force models --- p.49 / Chapter 6.1 --- Impact collision model --- p.51 / Chapter 6.2 --- Modified diffusion model --- p.53 / Chapter 6.3 --- Difficulties in the calculation of g(2)(t) --- p.54 / Chapter 6.4 --- Kn as a measured quantity --- p.57 / Chapter 7 --- Conclusion --- p.59 / Chapter A --- Alternative derivation of k and higher order corrections --- p.62 / Chapter B --- Evaluation of integrals in the exponential --- p.70 / Chapter B.1 --- Integral of the form ∫ts + ∫vu --- p.70 / Chapter B.2 --- Integrals of the form ∫ts + ∫vu + ∫yz --- p.72 / Chapter C --- Evaluation of four-click events --- p.74 / Bibliography --- p.76

Originally presented as the author's Thesis--Universität Karlsruhe. / Includes bibliographical references.

The effects of chain conformation on the photo-oxidation and green emission of poly(9,9-dioctylfluorenyl-2,7-diyl) (PFO) are investigated at both single molecule and ensemble levels. Single molecule studies reveal the conformation of PFO chains to be more globular when cast from THF than from toluene. Intensity transients of single molecules show that the elongated molecules cast from toluene have more fluctuations due to a fewer number of emitting centers on the polymer. Photochemical degradation leads to intensity fluctuations for the elongated molecules, while the globular chains show monotonic decays. Emission spectra of the single molecules show that photochemical oxidation leads to reduction in the emission of the molecule with no change in the emission spectra. No green emission is detected for single molecules indicating that formation of emissive ketone defects occurs rarely. Ensemble studies show that molecule cast from THF develop some green emission upon photodegredation while those cast from toluene don't. The increase in green in the globular molecules suggests that interchain contacts are necessary for the photochemical formation of emissive ketone defects in the PFO. All emission spectra of the aggregated and nonaggregated PFO during photooxidation are also analyzed by using a modified FranckCondon progression model with an additional independent Gaussian component and fitting results from single PFO spectrum. While emission spectrum of single PFO molecule shows a good fitting result to the model, the other two bulk PFO films display needs to introduce an additional term for better fit. This additional independent Gaussian component implies that green emission comes from non-Franck-Condon process. Rotational dynamics of poly(methyl acrylate) is investigated by single molecule spectroscopy. Polarized fluorescence transients from single rhodamine 6G dye embedded in polymer matrix above glass transition are analyzed and the correlation function of reduced linear dichroism is fit by a stretched exponential function. The fitting results suggest that non-exponential decay of correlation function. However, more rigorous study is needed because of the intrinsic statistical error of limited experimental data and the effect of high numerical objective.

This thesis has been motivated by the idea of harvesting the energy from ambient vibrations via nonlinear dynamics of the parametric pendulum. It aims to cover those aspects of the pendulum dynamics, which are relevant for energy extraction purposes and have not been addressed in previous studies. A simple system like parametric pendulum can experience variety of responses. One of them is rotary motion, which is characterised by significantly higher kinetic energy than oscillations and thus has a potential of delivering more energy, when subjected to the parametric excitation. Initially, a preliminary study on the dynamics of parametric pendulum has been conducted. This involved comparison of oscillatory and rotary responses with a view to application in energy harvesting, numerical continuation of rotary solutions and developing a control method for initiating and maintaining the desired response. As a next step, different forcing configurations have been considered, including pendulum excited along a tilted axis and a combined excitation, where pendulum additionally performs rocking action. The influence of the forcing arrangement on the lower limit of stability of rotary motion has been examined. The vibrations which can be observed in the environment are rarely perfectly harmonic. To provide more realistic results, the response of the pendulum under noisy excitation has been studied. Different types of noise have been considered and their influence on the pendulum rotation examined. One of the major energy sources, which could be utilised are the oscillating ocean surfaces. Therefore, a stochastic model of the sea wave has been constructed and the response of the pendulum system studied under parametric excitation by a wave profile. Finally, taking into account the imbalanced forces which rotating pendulum exerts on the supporting base, the model has been extended to a system of two pendulums. Synchronization in such a system was studied. The influence of the synchronization mode on the rotation of the pendulums and on the stability of supporting structure was considered. All of the numerical results presented in this thesis have been verified experimentally to ensure good correspondence.