Le rayonnement d'une source ultrasonore située sur l'une des interfaces d'une plaque anisotrope est étudié. Le calcul du tenseur de Green est effectué dans le cas général d'un problème 3D. Une décomposition en multiples réflexions /réfractions, constituant une série de rayons au sein de la plaque, est utilisée pour une comparaison théorie-expérience dans le cas d'un mono cristal de Cuivre. La vitesse de phase et la vitesse d'énergie sont mesurées en fonction de la fréquence ou de la direction d'observation, pour une plaque de carbone-époxy unidirectionnels, et comparées avec la théorie. / The ultrasonic radiation from a source located on one of the interfaces of an anisotropic plateis studied. The calculation of the Green tensor is performed in the general case of a 3Dproblem. Decomposition into multiple reflections /refractions, as a series of rays in the plate,is used for comparison between theory and experiment in the case of a single crystal of copper. The phase velocity and energy velocity are measured in terms of frequency ordirection of observation, for a plate of unidirectional carbon-epoxy, and compared withtheory.

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This thesis studies Lamb waves for long-range pipeline inspection. The property of Lamb waves propagation and the sensitivity of defect detection will be evaluated in this thesis. There are two groups of waves propagation in plate, first group of waves are called symmetrical Lamb waves, and the second group are called anti-symmetrical Lamb waves. Furthermore, there are three different mode types exist in hollow cylinder, such as the longitudinal, torsional, and flexural modes. By solving the characteristic equation of the Lamb wave problem, the dispersion character of the Lamb waves can be found. The phase and group velocity for different Lamb modes obtained from the dispersion curve are also studied in this thesis. In the experimental setup, the longitudinal wave is incident at certain incident angles and velocities to generate Lamb waves propagated on the stainless steel plate and carbon steel hollow cylinder. When the longitudinal waves are in the constructive interference in the medium, only one Lamb wave will propagate. As a result, compare with the measured data and theoretical predictions of the group velocities, it is observed that angle beam longitudinal waves offer an accurate and workable method for Lamb waves generation. To evaluate the sensitivity and resolution of the Lamb waves testing, additional experiments for detecting defects are carried out in this thesis. It is found that a single and pure Lamb wave is very useful for detection defects. Moreover, selected the non-dispersive Lamb modes for detection can keep the propagating wave shape without changing; also, only minimum energy is decayed as wave propagated.

Work was undertaken to determine the efficiency of growing lambs offered a fixed amount of roughage and concentrate as; 1) a mixed diet (M), containing 500 g/kg DM roughage and 500 g/kg DM concentrate, 2) split feeds (S), roughage alone followed by concentrate alone, 3) a mixture changing from roughage to concentrate (R-C), or concentrate to roughage (C-R), or 4) half the animals offered roughage and half concentrate (R/C). Lamb growth was predicted from computer models based on current feeding standards. In experiment (1), lambs were offered 50 kg roughage DM and 50 kg concentrate DM by strategies M and S. Lambs on strategy S took longer to consume their food and maintained a higher EBW ^0.75 than those on strategy M. However, the final EBW and EB composition of the two groups was similar. This contrasted with predicted results. The higher overall efficiency of lambs on strategy S was explained partly by associative effects reducing the energy available to lambs on strategy M, and partly by a higher efficiency of energy utilisation and/or a lower maintainance requirement of lambs on strategy S. In experiment (2), the influence of associative effects on strategies R-C and C-R was investigated. The prediction of dry matter digestibility (DMD, Y) from concentrate proportion (CONCP, X1) and dry matter intake (X2) showed no curvilinearity. DMD was linearly related to CONCP. The equations derived for each strategy were similar. In experiment (3), lambs were offered 52.5 kg roughage DM and 52.5 kg concentrate DM by strategies M, R-C, C-R and R/C. Lambs on strategies R-C, C-R and R/C took a similar time to consume their food and achieved a similar final EBW and EB composition. Their energy retention (ER) was similar to that predicted. Lambs on strategy M consumed their food faster than those on all other strategies and achieved a higher (NS) EBW, which contained more (NS) fat. Their ER was higher than predicted. The higher overall efficiency of lambs on strategy M was explained by differences in the ratio of protein: fat deposited and maintained by lambs on each strategy. The EB composition of all slaughtered lambs was within the limits for published data. Non-carcass composition could be used to predict EB composition. The results highlight the importance of the factors mentioned in determining the efficiency of lambs on each strategy.

Thesis (M.S. in Mechanical Engineer and M.S. in Mechanical Engineering)--Naval Postgraduate School, September 2009. / Thesis Advisor(s): Kwon, Young W. ; Pollak, Randall D. "September 2009." Description based on title screen as viewed on November 5, 2009. Author(s) subject terms: Lamb Waves, modeling, finite element, longitudinal, and shear mode, ANSYS, debonding, sensor, piezoelectric. Includes bibliographical references (p. 93-96). Also available in print.

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The purpose of this thesis is to determine the nature of Charles Lamb as revealed in his Elia essays. To this end, these essays form the major portion of the text. The general procedure for ascertaining what these excerpts indicate is as follows: first, the characteristics of Charles Lamb are determined from a study of the Elia essays; second, these characteristics are considered in relation to information derived from biographies. Careful attention is given to significant discrepancies between the essays and other sources.

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Video Image Analysis (VIA) is a digital camera based technology that extracts relevant information from images using purpose tailored image processing software. In the present work, the VSS2000 image analysis system from E+V Technology GmbH has been used in a large lamb abattoir to determine the value of carcasses in an objective, consistent and automated way. In this thesis results are reported of several experiments conducted within the framework of two UK-funded projects. The aims of the research were (i) the calibration and validation of the VIAtechnique for the evaluation of lamb carcasses under UK abattoir conditions, with the view to scientifically examine the accuracy and precision of information from the VIA systems as the basis for a value-based marketing system, (ii) to investigate the use of VIA measurements (weights of primal meat yields and carcass dimensional measurements) in sheep breeding programmes to improve carcass and meat quality and (iii) to evaluate the potential of this technology to reward increased carcass quality associated with the use of breeding strategies based on the inclusion of a quantitative trait locus (QTL) for improved muscularity. Accuracy, precision and consistency of The Meat and Livestock Commission (MLC) carcass classification scheme, currently used in UK abattoirs to evaluate carcass quality, was compared against the VIA system in the prediction of various primal joint weights. The results highlighted the advantage of the VIA system being on average 2% more accurate (measured as coefficient of determination: R2) and 12% more precise (measured as root meat squared error: RMSE) in predicting weight of primal meat yields (leg, chump, loin, breast and shoulder) of the lamb carcasses than the MLC carcass classification scheme. The genetic analysis of VIA-based predicted primal joint weights showed substantial additive genetic variance, suggesting that their use in sheep breeding programmes could improve carcass quality either by an improvement of conformation or by an increased weight of the most valuable primal cuts, without an increase in fatness. Favourable associations between VIA primal weights and performance traits indicate that selection based on VIA traits is possible without a negative effect on average daily gain, live weight and cold carcass weight. Although computer tomography (CT) and dissection found in related studies significant effects of a Texel muscling-QTL (TM-QTL) for increased muscularity in the loin region, in the present study they could not be identified by both, the current industry carcass evaluation system for conformation and fatness and the VIA system. A calibration of the VIA system against CT measurements resulted in improved VIA prediction equations for primal meat yields and also showed a moderate potential to estimate loin muscle traits measured by CT and to detect partially the effect of the TM-QTL on these traits. The results of the research demonstrated that VIA is a consistent method to measure carcass composition and that it improved the prediction (accuracy and precision) of primal meat yields compared to the present MLC scoring system. The estimated genetic parameters for VIA primal meat yields suggested that selection for increased lean meat yield from lamb carcass measured using VIA can contribute to genetic improvement of carcass quality without increasing carcass fatness. The results suggest that VIA technology installed in abattoirs could provide the means for the development of a value-based marketing system by paying for weights of the most valuable primal cuts measured using VIA.