Most high speed vessels are fitted with powerful high speed engines which are installed in confined spacesa nd, as a consequencec, ausea n extremely high level of noise and vibration. Often structure-borne sound power is transmitted to a sound carrying structure from a source via a number of contact points. In turn, the noise and vibration are propagated in the structure and could possibly cause an undesired noise radiation. In this study, a model for predicting power flow based on the mobility theory has been addressed. The unique parts of the study include the establishment of the relationship of mobility functions with respect to four-pole parameters and the dynamic stiffness coefficients of a coupled machine/mount/foundation system. Also expressions to represent the sound input power, the output power and the transmitted power in relation to mobility functions are clarified. From a detailed analysis of relevant literature, it is shown that no validated models for predicting the propagation of structure-bome noise within the intermediate frequency range of 125 Hz to lkHz exist. As a consequence, a new numerical stress wave model has been developed to bridge this knowledge gap. This innovative approach extends the earlier works of Cremer, Heckl and Ungar in the field of stress wave propagation. Finally, a novel holistic model has been developed to line up the transmission, propagation and radiation predictions of a machine induced noise and vibration in ship's structure to take in account the fluid-structure interaction effect. A number of experiment measurements have been performed to validate the established models. From the comparisons, the prediction models are shown to be credible with an accuracy higher than 95 per cent. The established models are of a generic nature and can be applicable to diverse engineering fields regarding to the predictions of structure-borne noise and vibration transmission, propagation and radiation. Applications of these models to characterize the vibration reduction countermeasures,a s in the case of resilient mounts and squeeze-film damping plates, from a machine are also discussed.

The study of arterial wave propagation is essential to understand the physiopathology of the cardiovascular system, as waves carry clinically relevant information. Impedance analysis was used for such type of studies, where results were presented in the frequency domain, but it was difficult to relate specific events to time points within the cardiac cycle. Therefore, a mathematical tool called wave intensity analysis was developed, initially using measurements of pressure and velocity (PU approach). However, the need to acquire such measurements in a non-invasive, direct and simultaneous fashion led to the development of the DU approach, a type of wave intensity analysis carried out using vessel diameter and flow velocity waveforms, thus giving up the pressure measurement. It is the only available technique, at present, able to extract wave intensity information without relying on distally recorded pressure measurements and on non-simultaneous recordings. Due to its non-invasive nature for collecting the required measurements, this technique has a potential use in clinical and research settings to investigate physiological changes under rapid perturbations, such as the ones introduced by exercise. In this thesis, the DU approach is performed by only using an ultrasound device and to extract information about cardio-arterial interaction in the human common carotid artery. In the first experimental chapter of this thesis, a reproducibility study of common carotid DU-derived wave intensity parameters was conducted on a healthy young cohort, both at rest and during exercise (semi-recumbent cycling). Carotid diameter and blood flow velocity features, as well as wave intensity parameters such as forward compression, backward compression and forward expansion wave peaks and energies, were overall fairly reproducible. In particular, diameter variables exhibited higher reproducibility and lower dispersion than corresponding velocity variables, whereas wave intensity energy variables exhibited higher reproducibility and lower dispersion than corresponding peaks. Local wave speed, calculated via lnDU-loop, a technique based only on local measurements of diameter and velocity and often associated with the DU approach, was also reproducible. It is possible to conclude that the DU-derived wave intensity analysis is reliable both at rest and during exercise. In a subsequent study, DU-derived wave intensity analysis was performed on a young trained cohort to investigate the contribution of cardiac and peripheral vascular alterations to common carotid wave intensity parameters, under rapid physiological perturbations, such as semi-recumbent cycling at incremental workrates, and subsequent recovery. Judging by the increase in local wave speed, the common carotid artery stiffened substantially as workrate increased whilst peak and energy of the forward and backward compression waves also increased, due to enhanced ventricular contractility, which was associated with larger reflections from the cerebral microcirculation and other vascular beds in the head. However, the reflection indices remained unchanged during exercise, highlighting that the increased magnitude of reflections is mainly due to the enhanced contractility, rather than changes in vascular resistance, at least at the carotid artery in young healthy individuals. The forward expansion wave increased during exercise, as the left ventricle actively decelerated blood flow in late systole, potentially improving filling time during diastole. In the early recovery, the magnitude of all waves returned to baseline value. Finally, the X wave, attributed to the reflection of the backward compression wave, had a tendency to increase during exercise and to return to baseline value in early recovery. A further development of wave intensity analysis came with the reservoir-wave approach, able to separate, from the pressure and velocity waveforms, the component solely due to the reservoir volume, for the correct evaluation of backward- and forward-travelling waves. A number of issues, however, still remains, involving specifically the lack of consensus over the fitting technique and over the value of the asymptotic pressure value (P ∞),used for the determination of the reservoir waveform. Therefore, to give a contribution to the debate involving the more correct model for the pressure and velocity reservoir-wave approach, a study aimed to investigate various common carotid hemodynamic and wave intensity parameters, using different fitting techniques and values of P ∞ currently available in literature, was performed and described in the last chapter of this thesis. The study demonstrated that different fitting method and values of P ∞ could bring significant variations in values and trends of hemodynamic and wave intensity parameters. However, despite the changes in the shape of the reservoir pressure waveform, its peak and integral with respect to time tended to remain constant. This is an important feature, because both reservoir peak pressure and its integral have been used in clinical settings for the calculation of diagnostic indicators. The reservoir and excess velocity peaks, instead, changed more significantly. This outcome, together with the concomitant substantial change in excess pressure peak and integral, may greatly affect wave intensity parameters. Wave intensity parameters were, in fact, significantly more sensitive to fitting techniques and values of P ∞ than pressure parameters. Finally, the wave speed did not substantially change, leading to the conclusion that the calculation of local vessel distensibility and/or compliance, when calculated from the excess components of the waveforms, seemed insensitive to fitting techniques and values of P ∞.

Ling, Chi Wai = 在等離子體鏈中使光變慢 / 凌志偉. / "September 2010." / Thesis (M.Phil.)--Chinese University of Hong Kong, 2010. / Includes bibliographical references (p. 73-76). / Abstracts in English and Chinese. / Ling, Chi Wai = Zai deng li zi ti lian zhong shi guang bian man / Ling Zhiwei. / Chapter 1 --- Introduction --- p.1 / Chapter 1.1 --- Slowing down of light --- p.1 / Chapter 1.2 --- Objectives of the thesis --- p.4 / Chapter 2 --- Review on Bergman-Milton Theory of Green Function --- p.5 / Chapter 2.1 --- Green function for Laplace operator --- p.5 / Chapter 2.2 --- Integral equation for two-component systems --- p.6 / Chapter 2.3 --- Symbolic solution for two-component systems --- p.10 / Chapter 2.4 --- An isolated dielectric sphere --- p.11 / Chapter 2.5 --- Extension to a collection of multi-interacting spheres --- p.13 / Chapter 3 --- Slowing Light by Multipolar Effect in Metal Nanoparticle Chains --- p.16 / Chapter 3.1 --- Evaluating the dispersion relations --- p.17 / Chapter 3.2 --- Results and discussions on multipolar effects --- p.20 / Chapter 4 --- Level Repulsion Phenomenon --- p.23 / Chapter 4.1 --- Two coupled oscillators --- p.24 / Chapter 4.1.1 --- Normal mode method --- p.24 / Chapter 4.1.2 --- Forccd oscillator method --- p.25 / Chapter 4.2 --- Metallic nanoshells --- p.25 / Chapter 4.3 --- Two coupled metal nanoparticles --- p.27 / Chapter 4.4 --- Diatomic spring-mass chain --- p.28 / Chapter 4.4.1 --- Dispersion relation --- p.29 / Chapter 4.4.2 --- Forced oscillator method --- p.30 / Chapter 5 --- Slowing Light by Hybridization of Bands in Plasmonic Chains --- p.34 / Chapter 5.1 --- Coupled dipole equation of plasmonic Chains --- p.34 / Chapter 5.2 --- Monatomic metal nanoparticle chains --- p.36 / Chapter 5.3 --- Diatomic chains formed by unshcllcd metal nanoparticles and shelled metal nanoparticles --- p.39 / Chapter 5.3.1 --- Formalism for evaluating dispersion relation --- p.39 / Chapter 5.3.2 --- Hybridization of bands --- p.42 / Chapter 5.3.3 --- Stopping light using photon-phonon assisted proccss --- p.45 / Chapter 5.3.4 --- Discussions --- p.47 / Chapter 5.4 --- Monatomic chains formed by nanoshells --- p.49 / Chapter 5.4.1 --- Formalism --- p.50 / Chapter 5.4.2 --- Numerical results and discussions --- p.54 / Chapter 5.4.3 --- Conclusions --- p.57 / Chapter 5.5 --- Diatomic chains formed by two types of dielectric shelled nano- particles --- p.60 / Chapter 5.5.1 --- Formalism for evaluating dispersion relation --- p.60 / Chapter 5.5.2 --- Results and discussions --- p.63 / Chapter 5.6 --- Yin-yang plasmonic chain --- p.68 / Chapter 6 --- Summary --- p.71 / Bibliography --- p.73 / Chapter A --- Properties of operator Γ --- p.77 / Chapter A.1 --- Hermitian Property of operator Γ --- p.77 / Chapter A.2 --- Eigenfunctions and eigenvalues of operator Γ for isolated spheres --- p.78 / Chapter B --- Drude Model and Polarizabilities of Spheres --- p.82 / Chapter B.1 --- Drude Model --- p.82 / Chapter B.2 --- Polarizabilities of spheres --- p.83 / Chapter C --- Dyadic Green's Function --- p.85

Data transfer rates on printed circuit boards are quickly approaching speeds that challenge the limits of todays technology. Inter-chip communication has increased dramatically. Currently data rates have reached 3.125 Gb/s on standard circuit board, but chip-to-chip digital communication has currently reached a plateau and several problems need to be addressed to significantly increase data transfer rates. Inductive and capacitive components of far end crosstalk (FEXT) conveniently cancel each other as they propagate on an interconnect transmission line, however the inductive and capacitive components of near end crosstalk(NEXT) add together and interfere with signals on adjacent receivers.<p>This paper proposes a novel solution for canceling crosstalk by adding extra circuitry to the receiver within the integrated circuit. This digital circuit delivers one of three appropriate levels of crosstalk compensation to the incoming signal. Since the circuit is digital, simple blocks can be used to implement it on a complimentary metal-oxide semiconductor (CMOS) integrated circuit and consume very little extra silicon.<p>This paper presents the compensation circuit and reports the results of the simulations, which demonstrate improved performance over the standard system. The compensation circuit is specifically aimed at adjacent input and output lines on a microchip. Simulations of a typical circuit board configuration operation have shown crosstalk that is only 15 dB lower than a received attenuated signal. The crosstalk cancellation circuit has been shown to improve this by as much as 10 dB.

Currently, the demand for natural gas is increasing as a result of high world energy consumption and rising environmental awareness. As the exploration of natural gas field is expanding towards remote regions, long distance pipelines have been developed. The economical, environmental, and safe movement of gas to the marketplace requires that transmission pipelines designed to operate at high pressure should possess adequate strength and improved toughness over a variety of temperature ranges. The purpose of this research was to investigate the effect of submerged arc welding (SAW) parameters on the quality and mechanical properties of X80 steel, which was supplied by IPSCO Inc., Regina. The welding was performed using single and double wires and different speeds (16.93, 19.69, 25.4, 29.63 and 33.87mm/s). The weld quality was evaluated using non-destructive testing methods (NDT) such as visual inspection, radiography, and ultrasonic test. The weld bead characteristics were studied using weld geometry measurements. The relationship between the microstructures and mechanical properties of weld deposits was studied by means of hardness measurements, Charpy V-notch test, lateral expansion measurements, tensile test, optical metallography, image analysis, scanning electron microscopy (SEM) and energy dispersive X-ray spectrometry (EDS).<p>It was found that there was a limit to which welding speed could be increased without the weld suffering from severe defects such as lack of penetration and undercut. The use of more than one welding wire improved the maximum welding speed at which good weld quality was maintained. Increasing the welding speed resulted in changes in the weld microstructure through the formation of higher percentage of fine acicular ferrite (AF) grain structure and a reduction in the amount of grain boundary ferrite (GBF) in the weld metal. Changing weld speed also reduced the size of the heat affected zone (HAZ). All of this resulted in improved the mechanical properties of the welded joints.

Data transfer rates on printed circuit boards are quickly approaching speeds that challenge the limits of todays technology. Inter-chip communication has increased dramatically. Currently data rates have reached 3.125 Gb/s on standard circuit board, but chip-to-chip digital communication has currently reached a plateau and several problems need to be addressed to significantly increase data transfer rates. Inductive and capacitive components of far end crosstalk (FEXT) conveniently cancel each other as they propagate on an interconnect transmission line, however the inductive and capacitive components of near end crosstalk(NEXT) add together and interfere with signals on adjacent receivers.<p>This paper proposes a novel solution for canceling crosstalk by adding extra circuitry to the receiver within the integrated circuit. This digital circuit delivers one of three appropriate levels of crosstalk compensation to the incoming signal. Since the circuit is digital, simple blocks can be used to implement it on a complimentary metal-oxide semiconductor (CMOS) integrated circuit and consume very little extra silicon.<p>This paper presents the compensation circuit and reports the results of the simulations, which demonstrate improved performance over the standard system. The compensation circuit is specifically aimed at adjacent input and output lines on a microchip. Simulations of a typical circuit board configuration operation have shown crosstalk that is only 15 dB lower than a received attenuated signal. The crosstalk cancellation circuit has been shown to improve this by as much as 10 dB.

Currently, the demand for natural gas is increasing as a result of high world energy consumption and rising environmental awareness. As the exploration of natural gas field is expanding towards remote regions, long distance pipelines have been developed. The economical, environmental, and safe movement of gas to the marketplace requires that transmission pipelines designed to operate at high pressure should possess adequate strength and improved toughness over a variety of temperature ranges. The purpose of this research was to investigate the effect of submerged arc welding (SAW) parameters on the quality and mechanical properties of X80 steel, which was supplied by IPSCO Inc., Regina. The welding was performed using single and double wires and different speeds (16.93, 19.69, 25.4, 29.63 and 33.87mm/s). The weld quality was evaluated using non-destructive testing methods (NDT) such as visual inspection, radiography, and ultrasonic test. The weld bead characteristics were studied using weld geometry measurements. The relationship between the microstructures and mechanical properties of weld deposits was studied by means of hardness measurements, Charpy V-notch test, lateral expansion measurements, tensile test, optical metallography, image analysis, scanning electron microscopy (SEM) and energy dispersive X-ray spectrometry (EDS).<p>It was found that there was a limit to which welding speed could be increased without the weld suffering from severe defects such as lack of penetration and undercut. The use of more than one welding wire improved the maximum welding speed at which good weld quality was maintained. Increasing the welding speed resulted in changes in the weld microstructure through the formation of higher percentage of fine acicular ferrite (AF) grain structure and a reduction in the amount of grain boundary ferrite (GBF) in the weld metal. Changing weld speed also reduced the size of the heat affected zone (HAZ). All of this resulted in improved the mechanical properties of the welded joints.

The Mass Rapid Transit (MRT) systems have been built in many metropolitans to solve the public transportation problem such as traffic congestion. With such high investment cost, it is important to design a proper operation strategy to reduce the operational cost which achieving the system performance. With less ridership as compared to Taipei MRT system, the minimization of social cost which consists of energy consumption and the traveling time to complete the journey, has been investigated for Kaohsiung MRT (KMRT) system. By this way, the optimal coasting speed between train stations is solved according to the ridership and distance between the stations. The artificial neural network (ANN) has proposed in this thesis to determine the optimal coasting speed of the train set. The energy consumption and the traveling time to complete the journey between stations with various riderships are calculated by exactly the train performance simulation to generate the training data set. The objective function is defined by considering the energy consumption and the traveling time cost of passengers. By performing the ANN training, the ANN model is therefore obtained, which can be used to solve the optimal coasting speed of train sets. To demonstrate the effectiveness of the proposed ANN model, the forecasting of annual ridership for both Orange Line and Red Line of KMRT system is used. The optimal coasting speed and the corresponding profile of power consumption have been solved to minimize the social cost of MRT systems operation.

Thèse : Sciences physiques : Paris, Faculté des sciences : 1853. / Titre provenant de l'écran-titre.

Thesis (M.S. in Engineering Acoustics)--Naval Postgraduate School, December 2009. / Thesis Advisor(s): Kapolka, Daphne ; Smith, Kevin B. "December 2009." Description based on title screen as viewed on January 29, 2010. Author(s) subject terms: Particle velocity, beamforming, beam pattern, acoustic array, acoustic vector sensor, Microflown, hybrid array, frequency spectrum, linear array, directional. Includes bibliographical references (p. 151-153). Also available in print.