ABSTRAT In this thesis, we focused on the fabrication and frequency-modulation of £f/4 mode dual-band solidly mounted resonators and filters. To accomplish the Bragg reflector, the RF/DC magnetron sputtering system with dual targets is adopted to deposit alternating layers of quarter-wavelength Mo and SiO2 thin films. We tune the fabrication parameters in accordance with the AFM measurement and achieve a low roughness of 2.9nm on a nine-layer reflector. The piezoelectric layer, aluminum nitride (AlN) thin films, is deposited on the Bragg reflector by means of reactive RF magnetron sputtering. We alter the distance between substrate and target is altered to deposit AlN with various c-axis tilting angle which results in longitudinal and shear acoustic waves at the same time. Furthermore, we use mass loading effect to modulate the resonance frequency and fabricate £k- ladder type filters. In various numbers of reflector layers, the optimum frequency response is obtained with return loss of -26dB, in a SMR on a 3.5 pair reflector. To investigate the relationship between longitudinal and shear resonance in different resonance frequency, we alter the c-axis tilting angle of AlN as well as various mass loading on the SMRs. Based on the experimental results, the ratio of longitudinal to shear resonance frequency remains a constant value despite various c-axis tilting angle of AlN and mass loading on the SMRs. In addition, the electromechanical coupling coefficient, Kt2, of shear resonance raises with the increase of c-axis tilting angle of AlN. Finally,we have successfully fabricated SMRs with frequency modulataion of 3,899.68 Hz-cm2/ng and £k-ladder type filters with 26 MHz bandwidth.

The goal of this work is to design and fabricate an autonomous acoustic recording system which is low cost, reconfigurable and portable for acoustic research. The system consists of four components, including a compact single-board computer (Celeron 1G), a 12-bit A/D converter (PCM-3718HO), a 20/40 dB gain amplifier and an useful power management circuit board. C and LabVIEW programs with multiple threads are developed to control the I/O's, digitize the underwater acoustic signals and stream data to the hard disk continuously. Currently, the throughput of data stream attains to 83 kHz. It were tested by six significant experiments to show its feasibility. At first, taking the function generator as signal source to verify no distortion caused by the system. Two ITC-6050C hydrophones are connected to the system as the receivers. The system was tested with experimental propeller producing broadband noise to calibrate the hydrophones in the experimental sink. To verify their performance, the receivers also work with the calibrated one B & K 8104 for reference. In order to understand the influence of self-noise, the system is planned to record known signal producing by hydrophone CTG-0708. By repeating similar calibration experiment, the system operates with an autonomous recording system Bioacoustic probe to understand what deficiency we should improve afterward. Further, a field test was conducted in the designated natural laboratory of shallow bay area. Post-processing of the data resulted in range-frequency plot shows that the interference pattern reported in the literature was captured. According to above-mentioned tesing, the system can be applied to underwater acoustics. This system, connected with multiple hydrophones, will be applied in the research for target detection, the harbor protection and so on.

This thesis investigates the relevance between the acoustic resonance and power harmonics on a metal halide lamp. First, a sinusoidal current ranging from 20 kHz to 400 kHz is used to drive a 70 W metal halide lamp. Second, a hybrid-current test circuit is designed to generate a current waveform consisting of a low-frequency square-wave and a high-frequency sinusoidal wave. Both of the frequency and the amplitude can be adjusted independently. The test lamp is deliberately driven at its acoustic-resonance eigen-frequencies to observe the effect of the power spectrum on the degree of the acoustic resonance. The experimental results indicate that the occurrence of acoustic resonance is indeed affected by the DC level and related power harmonics. The power harmonic spectrum that elucidates the initiation of acoustic resonance is deduced from the observations. It is found that the power harmonics that excites acoustic resonance can be divided into three categories. The first is independent of the average lamp power; it excites acoustic resonance only if the magnitude of its power exceeds a specific level. The thresholds of power harmonics belong to the second category are proportional to their DC powers. One can also find those remaining power harmonics belong to the third category. The power harmonic spectrum of the acoustic resonance is demonstrated by driving the test lamp with quasi-square-wave and triangle-wave currents. This work helps advance the understanding of the phenomena and mechanism of acoustic resonance in a metal halide lamp.

A new resistive Geodesic Acoustic Mode (GAM) theory is developed by two-fluids analysis and resistive gyro-kinetic formulation in this thesis. An analytical expression is obtained for the resistive GAM frequency. This theory suggests a large collision frequency will prohibit the parallel current in tokamak, which establishes the cross-field charge neutrality condition ∇·J⊥= 0 for the existence of GAM at the edge plasma of tokamak. Therefore, the resistive GAM theory provides a more plausible explanation to edge GAM phenomena. Various probe arrays are designed and installed in the STOR-M tokamak to search for the poloidal GAM phenomena. A series of experiments were conducted in the L-mode and RMP discharges. The FFT and wavelet analyses indicate the existence of GAM phenomena in STOR-M, and the observed GAM frequencies match the theoretical predication using the resistive GAM model.

Bubble and cavitation effects phenomena can be encountered in two-phase gas-liquid systems in industry. In certain industries, particularly high-risk systems such as a nuclear reactor/plant, the detection of bubble dynamics, and the monitoring and measurement of their characteristics are necessary in controlling temperature. While in the petro-chemical engineering industry, such as oil transportation pipelines, the detection and monitoring of bubbles/cavitation phenomena are necessary to minimise surface erosion in fluid carrying components or downstream facilities. The high sensitivity of Acoustic Emission (AE) technology is feasible for the detection and monitoring of bubble phenomena in a two phase gas-liquid system and is practical for application within the industry. Underwater measurement of bubble oscillations has been widely studied using hydrophones and employing acoustic techniques in the audible range. However, the application of Acoustic Emission (AE) technology to monitor bubble size has hitherto not been attempted. This thesis presents an experimental investigation aimed at exploring AEs from gas bubble formation, motion and destruction. AE in this particular investigation covers the frequency range of between 100 kHz to 1000 kHz. The AE waveform analysis showed that the AE parameter from single bubble inception and burst events, i.e. AE amplitude, AE duration and AE energy, increased with the increase of bubble size and liquid viscosity. This finding significantly extends the potential use of AE technology for detecting the presence of bubbles in two-phase flow. It is concluded that bubble activity can be detected and monitored by AE technology both intrusively and non-intrusively. Furthermore, the bubble size can be determined by measurement of the AE and this forms the significant contribution of this thesis.

Although Icelandic and Norwegian killer whales are thought to have been in contact prior to the collapse of the herring stock in the 1960s, the Northeast Atlantic killer whales currently seem to show high site fidelity. So far, photoidentification data have suggested movement of a few individuals between East Iceland and North Scotland, and two calls have been shown to be shared by the Icelandic and Norwegian populations. Based on previous and newly analysed call samples, the aim of this study was to describe the geographic variation in the vocal repertoire of the Northeast Atlantic killer whales. Recordings have been conducted off Southwest Iceland in the summers 2004, 2008 and 2009 using sound recording tags attached using suction cups (Dtags), a 4-element vertical hydrophone array and a 2-element towed hydrophone array. From the 57 hours of recording analysed, 1742 calls were classified. In total, 56 distinct call categories composed of 35 call types and 31 subtypes were identified. This discrete call repertoire contained less biphonic calls but more calls composed of buzzes and/or clicks than the Norwegian repertoire. The reasons for these differences remain unknown. One Icelandic call subtype was defined as a compound call, a type of call that is common in the Norwegian population. The comparison of the different vocal repertoires of Northeast Atlantic showed four good or likely call matches in herring-eating killer whales (one between Southwest Iceland and Shetland, one between East Iceland and Norway, and two between Shetland and Norway). No matches were found between Southwest Iceland and East Iceland. I suggest that the four shared calls are most likely to have come from a common ancestral pod and have been transmitted through vocal learning. Over time, geographic isolation of the groups induced by changes in the migratory patterns of the herring might have been accompanied by divergence in their call repertoires.

The aim of this inquiry was to investigate the most appropriate measures to reduce noise impacts from road traffic on the Nydala recreational area in Umeå municipality due to the planned re-routing of the E4 motorway to an existing road along this area. The sound environment is an important part in the experience when we are visiting recreational areas. Noise is not only disturbing; the liberty from unwanted sounds also allows us to perceive natural sounds that are a benefit for the cultural experience. Therefore it is important to take actions to protect this well used area from traffic noise. The reasonable options to avoid noise impact in this case are to lower the speed limit, using a noise reducing coating or use noise protection screens and walls. To estimate the measures suitability the starting points were to measure the effects on noise, the impact on the landscape, coasts and other possible side effects. It is important that the noise issue may not be replaced by other problems such as barrier effects, significant effects on the landscape or worsening living environment. To assess the reducing effect of the noise, calculations have been made. These showed that the measures that reduce noise spread were more favorable compared to those which prevent noise generation. The most appropriate measure in this case, based on the noise impact and influence on the landscape, is a 2 meter high acoustic screen in a combination of 0,5 meter wood and 1,5 meter tempered

<p>Automated acoustic sensing systems are required to detect, classify and localize acoustic signals in real-time. Despite the fact that humans are capable of performing acoustic sensing tasks with ease in a variety of situations, the performance of current automated acoustic sensing algorithms is limited by seemingly benign changes in environmental or operating conditions. In this work, a framework for acoustic surveillance that is capable of accounting for changing environmental and operational conditions, is developed and analyzed. The algorithms employed in this work utilize non-stationary and nonparametric Bayesian inference techniques to allow the resulting framework to adapt to varying background signals and allow the system to characterize new signals of interest when additional information is available. The performance of each of the two stages of the framework is compared to existing techniques and superior performance of the proposed methodology is demonstrated. The algorithms developed operate on the time-domain acoustic signals in a nonparametric manner, thus enabling them to operate on other types of time-series data without the need to perform application specific tuning. This is demonstrated in this work as the developed models are successfully applied, without alteration, to landmine signatures resulting from ground penetrating radar data. The nonparametric statistical models developed in this work for the characterization of acoustic signals may ultimately be useful not only in acoustic surveillance but also other topics within acoustic sensing.</p> / Dissertation

For centuries scientific ingenuity and innovation have been influenced by Mother Natures perfect design. One of her more elusive designs is that of the sensory olfactory system, an array of highly sensitive receptors responsible for chemical vapor recognition. In the animal kingdom this ability is magnified among canines where ppt (parts per trillion) sensitivity values have been reported. Today, detection dogs are considered an essential part of the US drug and explosives detection schemes. However, growing concerns about their susceptibility to extraneous odors have inspired the development of highly sensitive analytical detection tools or biosensors known as electronic noses. In general, biosensors are distinguished from chemical sensors in that they use an entity of biological origin (e.g. antibody, cell, enzyme) immobilized onto a surface as the chemically-sensitive film on the device. The colloquial view is that the term biosensors refers to devices which detect the presence of entities of biological origin, such as proteins or single-stranded DNA and that this detection must take place in a liquid. Our biosensor utilizes biomolecules, specifically IgG monoclonal antibodies, to achieve molecular recognition of relatively small molecules in the vapor phase.

The object of this thesis research is to facilitate the appraisal and analysis of the signatures of the modern acoustic wave biosensors, as well as to improve the experimental methodology to enhance sensor performance. For this purpose, both theoretical characterization of acoustic wave sensor signatures and experimental studies for the most frequently used acoustic wave biosensors, the liquid phase QCM (quartz crystal microbalance) and the vapor phase SAW (surface acoustic wave) sensors, are presented. For the study of SAW vapor phase detection, the author fabricated different types of two-port SAW resonator sensors on quartz substrates and designed and performed a significant number of detection experiments. These were conducted both with calibrated or known target samples under laboratory conditions at Georgia Tech Hunt Lab and with samples of unknown concentrations such as seized crack cocaine (courtesy of Georgia Bureau of Investigation, GBI) to see the sensors capability to work in the field conditions. In addition, the dependence of the SAW sensor signatures on specific locations of the surface perturbation was investigated to account for some observed abnormal responses. Finally, a novel approach to classify and visualize chemically analogous substances is introduced. The author expects that the thesis work herein may contribute to the study of the modern acoustic wave biosensors which includes but is not limited to: the establishment of underpinning theory that will aid in the evaluation of the signatures; the practical aspects of design and fabrication of SAW devices specific to the vapor phase immunoassay; the development of efficient experimental methodologies; the strategic immobilization of a biolayer on SAW resonator based biosensors; and, the acquisition of reference data for the development of commercial acoustic wave sensors.