The formulation and implementation of a low-order vibration controller using Linear Quadratic (LQ) modern control theory is demonstrated. The controller is implemented to reject persistent disturbances of the fundamental mode of a simply supported plate. The plate is excited by a 60 Hz harmonic excitation, a narrowband excitation centered at 60 Hz, and an impulse excitation caused by an impact hammer. The extraction of the eigen-properties of the first four modes of the plate is presented. The eigen-properties form the basis of the modal model of the plate. Also, a brief discussion of the control law is provided. Simulated and experimental results are presented for the transputer-based, parallel-processing control system. The steady-state fundamental modal amplitude is attenuated by more than an order of magnitude at the disturbance frequency, and the modal damping is doubled. Additionally, the implementation issues of applying the LQG controller are addressed including temporal and spatial aliasing considerations. / Master of Science

An optical detection technique is developed to detect and measure the resonant vibration of the cellular membrane. Biological membranes are active components of living cells and play a complex and dynamic role in life processes. They are believed to have oscillation modes of frequencies in the range of 1 to 1000 GHz. To measure such a high-frequency vibration, a linear laser cavity is designed to produce a train of femtosecond pulses of adjustable repetition rate. The method is then directly applied to liposomes, "artificial membrane", stained with a liphophilic potential sensitive dye. The spectral behavior of a selection of potential sensitive dyes in the membrane is also studied.

No description available.

published_or_final_version / Mechanical Engineering / Doctoral / Doctor of Philosophy

This thesis describes a method to detect, localize and identify a faulty bearing in a rotating machine using narrow band envelope analysis across an array of accelerometers. This technique is developed as part of the machine monitoring system of an ocean turbine. A rudimentary mathematical model is introduced to provide an understanding of the physics governing the vibrations caused by a bearing with a raceway defect. This method is then used to detect a faulty bearing in two setups : on a lathe and in a dynamometer. / by Nicholas Waters. / Thesis (M.S.C.S.)--Florida Atlantic University, 2012. / Includes bibliography. / Mode of access: World Wide Web. / System requirements: Adobe Reader.

During the last decade, Raman microscopy is experiencing rapid development and increasingly applied in biological and medical systems. Especially, stimulated Raman scattering (SRS) microscopy, which significantly improves the sensitivity of Raman scattering through stimulated emission, has allowed direct visualization of many species that are previously challenging with conventional fluorescence imaging. Compared to fluorescence, SRS imaging requires no label or small label on the target molecule, thus with minimal perturbation to the molecule of interest. Moreover, Raman scattering is free from complicated photophysical and photochemical processes such as photobleaching, and has intrinsically narrower linewidth than fluorescence emission. This allows multiplexed Raman imaging with minimal spectral crosstalk and excellent photo-stability. To achieve the full potential of Raman microscopy, vibrational probes have been developed for Raman imaging. Multiple Raman probes with a few atoms in size are applied in Raman imaging with high sensitivity and specificity. An overview of both fluorescence and Raman microscopy and their imaging probes is given in Chapter 1 with a brief discussion on the SRS theory. Built on the current progress of Raman microscopy and vibrational probes, I write on my research in the development of carbon-deuterium, alkyne and nitrile probes for visualizing choline metabolism (Chapter 2), glucose uptake activity (Chapter 3), complex brain metabolism (Chapter 4) and polymeric nanoparticles (Chapter 5) in live cells and tissues, as well as the development of polyyne-based vibrational probes for super-multiplexed imaging, barcoding and analysis (Chapter 6).

Response characteristics and tactile coding capacities of single neurons of the dorsal column nuclei (DCN), and the dorsal horn, in particular, neurons of the spinocervical tract (SCT), were investigated in anaesthetized cats. Purely dynamically-sensitive tactile neurons of the DCN could be divided into two classes, one associated with hair follicle afferent (HFA) input, the other with Pacinian corpuscle (PC) input. The HFA-related class was most sensitive to low-frequency (&lt50 Hz) vibration, had phaselocked responses to vibration frequencies up to ~75 Hz and had a graded response output as a function of vibrotactile intensity changes. PC-related neurons had broader vibrotactile sensitivity, extending to ~300 Hz with tightest phaselocking between 50 and 200 Hz. The SCT neurons in the lumbar dorsal horn had tactile receptive fields on the hairy skin of the hindlimb and a very limited capacity to signal, in a graded way, the intensity parameter of the vibrotactile stimulus. Furthermore, because of their inability to respond on a cycle-by-cycle pattern at vibration frequencies above 5-10 Hz, these neurons were unable to provide any useful signal of vibration frequency beyond ~5-10 Hz, in contrast to DCN neurons. In the parallel human psychophysical study, the capacity for vibrotactile frequency detection and discrimination was examined in five subjects in glabrous and hairy skin. The vibrotactile detection threshold values obtained at four standard frequencies of 20, 50, 100 and 200 Hz were markedly higher on the hairy skin than on the glabrous skin. The discrimination task was examined by means of a two-alternative, forced-choice psychophysical procedure. Measures of the discriminable frequency increment (?????) and the Weber Fraction (????? / ??), revealed similar capacities for frequency discrimination at the two different skin sites at the standard frequencies of 20, 100 and 200 Hz, but an equivocal difference at 50 Hz. Cutaneous local anaesthesia in the dorsal forearm produced a marked impairment in vibrotactile detection and discrimination at the low frequencies of 20 and 50 Hz but little effect at higher frequencies, confirming that vibrotactile detection and discrimination in hairy skin depend upon superficial receptors at low vibrotactile frequencies, but depend on deep, probably Pacinian corpuscle receptors for high frequencies.

No description available.

Response characteristics and tactile coding capacities of single neurons of the dorsal column nuclei (DCN), and the dorsal horn, in particular, neurons of the spinocervical tract (SCT), were investigated in anaesthetized cats. Purely dynamically-sensitive tactile neurons of the DCN could be divided into two classes, one associated with hair follicle afferent (HFA) input, the other with Pacinian corpuscle (PC) input. The HFA-related class was most sensitive to low-frequency (&lt50 Hz) vibration, had phaselocked responses to vibration frequencies up to ~75 Hz and had a graded response output as a function of vibrotactile intensity changes. PC-related neurons had broader vibrotactile sensitivity, extending to ~300 Hz with tightest phaselocking between 50 and 200 Hz. The SCT neurons in the lumbar dorsal horn had tactile receptive fields on the hairy skin of the hindlimb and a very limited capacity to signal, in a graded way, the intensity parameter of the vibrotactile stimulus. Furthermore, because of their inability to respond on a cycle-by-cycle pattern at vibration frequencies above 5-10 Hz, these neurons were unable to provide any useful signal of vibration frequency beyond ~5-10 Hz, in contrast to DCN neurons. In the parallel human psychophysical study, the capacity for vibrotactile frequency detection and discrimination was examined in five subjects in glabrous and hairy skin. The vibrotactile detection threshold values obtained at four standard frequencies of 20, 50, 100 and 200 Hz were markedly higher on the hairy skin than on the glabrous skin. The discrimination task was examined by means of a two-alternative, forced-choice psychophysical procedure. Measures of the discriminable frequency increment (?????) and the Weber Fraction (????? / ??), revealed similar capacities for frequency discrimination at the two different skin sites at the standard frequencies of 20, 100 and 200 Hz, but an equivocal difference at 50 Hz. Cutaneous local anaesthesia in the dorsal forearm produced a marked impairment in vibrotactile detection and discrimination at the low frequencies of 20 and 50 Hz but little effect at higher frequencies, confirming that vibrotactile detection and discrimination in hairy skin depend upon superficial receptors at low vibrotactile frequencies, but depend on deep, probably Pacinian corpuscle receptors for high frequencies.

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