Thesis (M.Sc.)--York University, 2008. Graduate Programme in Earth and Space Science. / Typescript. Includes bibliographical references (leaves 108-115). Also available on the Internet. MODE OF ACCESS via web browser by entering the following URL: http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&res_dat=xri:pqdiss&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&rft_dat=xri:pqdiss:MR51581

Made available in DSpace on 2014-08-13T14:50:43Z (GMT). No. of bitstreams: 0 Previous issue date: 2013-12-18Bitstream added on 2014-08-13T18:00:52Z : No. of bitstreams: 1 000750830_20151201.pdf: 137582 bytes, checksum: c6b1787fdc767500949d3ce0f9a758ca (MD5) Bitstreams deleted on 2015-12-01T09:08:22Z: 000750830_20151201.pdf,. Added 1 bitstream(s) on 2015-12-01T09:09:21Z : No. of bitstreams: 1 000750830.pdf: 886980 bytes, checksum: 58e9c376ed855a26b14619c70052a663 (MD5) / Objetivando-se o estudo morfológico dos músculos, qualitativo das carnes e a correlação dos parâmetros avaliados do Gluteus medius, Longissimus e Triceps brachii de animais terminados em diferentes índices de área foliar (IAF) (0,8; 1,4; 2,0 e 2,6%) de pastagem composta por TIFTON 85 (Cynodon spp.) sendo suplementados ou não com concentrado proteico energético (0,7% do peso vivo), utilizou-se 48 cordeiros SPRD, não castrados, com peso médio de 15 kg. Os animais foram confinados pelo período da noite em baias individuais, onde receberam o suplemento com 18% PB. Atingidos o peso corporal médio de 32 kg, os animais foram abatidos e amostras dos músculos Gluteus medius, Longissimus e Triceps brachii foram coletadas para avaliação dos parâmetros morfológicos: frequência, área e área total relativa (ATR). Atingido o post mortem (24 horas após o abate) coletaram-se amostras das porções do Gluteus medius, Longissimus e Triceps brachii para avaliação das características qualitativas: pH, cor, perda de peso por cocção (PPC) e maciez (FC). Não ocorreram interações (P>0,05) entre os IAF e os níveis de suplementação para os valores de pH dos músculos avaliados. No estudo do Gluteus medius, manter os animais em IAF mais elevado e sem suplementação pode ser uma boa alternativa para o alcance de parâmetros desejáveis pelos consumidores de carne ovina. Na avaliação do músculo Triceps brachii, animais mantidos em IAF 1,4 e sem suplementação apresentam maior luminosidade da carne L* e menor teor de amarelo b*. Houve correlação negativa e significativa (P<0,05) entre as fibras FOG e SO e FOG e FG caracterizando o processo de modulação da fibra FOG e refletindo na proporcionalidade da frequência das fibras musculares SO e FG dos músculos Gluteus medius e Longissimus... / Aiming at the morphological study of qualitative muscles of the meat and the correlation of the evaluated parameters Gluteus medius, Longissimus and Triceps brachii animals finished in different leaf area index (LAI) ( 0,8;1,4; 2,0 and 2,6%) of pasture comprising TIFTON 85 (Cynodon spp.) being supplemented or not with energy protein concentrate (0,7% of body weight), we used 48 lambs SPRD, uncastrated, with an average weight of 33,7 lbs . The animals were confined for the duration of the night in individual stalls, where they supplement with 18% crude protein. Reached 32 kg body weight, the animals were slaughtered and samples of the Gluteus medius, Longissimus and Triceps brachii were collected for evaluation of morphological parameters: frequency, area, and total area relative. Hit the post mortem (24 hours after slaughter) and rigor mortis, samples were collected from portions of the Gluteus medius, Longissimus and Triceps brachii and to evaluate the quality characteristics: pH, color, weight loss by cooking and smoothness (shear force). There were no interactions (P>0,05) between the LAI and the levels of supplementation for the pH values of the muscles. In the study of the Gluteus medius, keep animals in higher LAI and without supplementation may be a good alternative to the achievement of desirable parameters by consumers of sheep meat. In assessing Triceps brachii muscle, animals kept in IAF 1,4 and without supplementation have higher meat lightness L* and lower yellowness b*. There was a significant negative correlation (P<0,05) between the SO and FOG, FOG and FG fibers and characterizing the process of modulation, and FOG fiber reflecting the proportionality of frequency of SO and FG muscle fibers of the muscles Longissimus and Gluteus medius...

Orientadora: Hirasilva Borba / Banca: Emanuel Almeida de Oliveira / Banca: Marco Antônio Trindade / Resumo: Objetivando-se o estudo morfológico dos músculos, qualitativo das carnes e a correlação dos parâmetros avaliados do Gluteus medius, Longissimus e Triceps brachii de animais terminados em diferentes índices de área foliar (IAF) (0,8; 1,4; 2,0 e 2,6%) de pastagem composta por TIFTON 85 (Cynodon spp.) sendo suplementados ou não com concentrado proteico energético (0,7% do peso vivo), utilizou-se 48 cordeiros SPRD, não castrados, com peso médio de 15 kg. Os animais foram confinados pelo período da noite em baias individuais, onde receberam o suplemento com 18% PB. Atingidos o peso corporal médio de 32 kg, os animais foram abatidos e amostras dos músculos Gluteus medius, Longissimus e Triceps brachii foram coletadas para avaliação dos parâmetros morfológicos: frequência, área e área total relativa (ATR). Atingido o post mortem (24 horas após o abate) coletaram-se amostras das porções do Gluteus medius, Longissimus e Triceps brachii para avaliação das características qualitativas: pH, cor, perda de peso por cocção (PPC) e maciez (FC). Não ocorreram interações (P>0,05) entre os IAF e os níveis de suplementação para os valores de pH dos músculos avaliados. No estudo do Gluteus medius, manter os animais em IAF mais elevado e sem suplementação pode ser uma boa alternativa para o alcance de parâmetros desejáveis pelos consumidores de carne ovina. Na avaliação do músculo Triceps brachii, animais mantidos em IAF 1,4 e sem suplementação apresentam maior luminosidade da carne L* e menor teor de amarelo b*. Houve correlação negativa e significativa (P<0,05) entre as fibras FOG e SO e FOG e FG caracterizando o processo de modulação da fibra FOG e refletindo na proporcionalidade da frequência das fibras musculares SO e FG dos músculos Gluteus medius e Longissimus... / Abstract: Aiming at the morphological study of qualitative muscles of the meat and the correlation of the evaluated parameters Gluteus medius, Longissimus and Triceps brachii animals finished in different leaf area index (LAI) ( 0,8;1,4; 2,0 and 2,6%) of pasture comprising TIFTON 85 (Cynodon spp.) being supplemented or not with energy protein concentrate (0,7% of body weight), we used 48 lambs SPRD, uncastrated, with an average weight of 33,7 lbs . The animals were confined for the duration of the night in individual stalls, where they supplement with 18% crude protein. Reached 32 kg body weight, the animals were slaughtered and samples of the Gluteus medius, Longissimus and Triceps brachii were collected for evaluation of morphological parameters: frequency, area, and total area relative. Hit the post mortem (24 hours after slaughter) and rigor mortis, samples were collected from portions of the Gluteus medius, Longissimus and Triceps brachii and to evaluate the quality characteristics: pH, color, weight loss by cooking and smoothness (shear force). There were no interactions (P>0,05) between the LAI and the levels of supplementation for the pH values of the muscles. In the study of the Gluteus medius, keep animals in higher LAI and without supplementation may be a good alternative to the achievement of desirable parameters by consumers of sheep meat. In assessing Triceps brachii muscle, animals kept in IAF 1,4 and without supplementation have higher meat lightness L* and lower yellowness b*. There was a significant negative correlation (P<0,05) between the SO and FOG, FOG and FG fibers and characterizing the process of modulation, and FOG fiber reflecting the proportionality of frequency of SO and FG muscle fibers of the muscles Longissimus and Gluteus medius... / Mestre

Made available in DSpace on 2014-06-11T19:27:43Z (GMT). No. of bitstreams: 0 Previous issue date: 2008-08-18Bitstream added on 2014-06-13T20:36:10Z : No. of bitstreams: 1 valle_rcm_me_botfmvz.pdf: 436555 bytes, checksum: f6774251b4833531c28e7837601e193f (MD5) / Universidade Estadual Paulista (UNESP) / O estudo teve por objetivo avaliar a utilização de ultra-som em tempo real - UTR com transdutores de diferentes freqüências na avaliação in vivo cordeiros de diferentes genótipos e das diferenças entre operadores. Foram utilizados 116 cordeiros machos desmamados, de diferentes raças, oriundos de rebanhos comerciais, nascidos no mesmo intervalo de data, durante os anos de 2006 e 2007, confinados com a mesma dieta e avaliados por ultra-sonografia 07 dias antes do abate. Utilizou-se de dois equipamentos de ultra-som Pie Medical Scan Vet 200, equipados com transdutores linear de 18cm e 8cm e, 3,5MHz e 7,5MHz respectivamente. Foram utilizadas correlações de Pearson para verificar a existência de correlação linear entre os métodos de ultra-som, entre raças, entre anos, entre métodos M1(transdutor de 18cm e freqüência 3,5MHz) e M2 (transdutor de 8cm e freqüência 7,5MHz) e as medidas de carcaça (rendimento, índice de compacidade da perna – ICP e índice de compacidade da carcaça – ICC). Houve correlação média entre as duas metodologias avaliadas, podendo viabilizar a otimização do equipamento de ultra-som, uma vez que o transdutor linear de 8cm e 7,5MHz, demonstrou-se viável para avaliação de gordura subcutânea em cordeiros. / The trial had the objective of evaluating the use of real time ultrasound techniques with two different transducers on the in vivo evaluation of lambs from different genotypes and the differences among operator. 116 weaned male lambs from commercial flocks with different breeds, during the year 2006 and 2007, born in the same interval of time, confined and fed the same diet were evaluated 7 days before slaughter. Two Pie Medical Scan Vet 200 ultra-sound equipments with transducers of 18cm and 8cm with frequencies of 3.5MHz and 7.5MHz, respectively, were used.Pearson´s Correlation were performed to verify the linear correlation between ultra sound transducer (18cm and frequency of 3.5MHz and 8cm and frequency of 7.5MHz), breeds, years and carcass measurements (leg compacity index and carcass compacity index). There was a medium correlation between the two methodology evaluated and the 8cm, 7.5 MHz transducer showed to be viable to evaluate the subcutaneous fat in lambs.

Made available in DSpace on 2014-06-11T19:28:22Z (GMT). No. of bitstreams: 0 Previous issue date: 2010-02-26Bitstream added on 2014-06-13T20:37:12Z : No. of bitstreams: 1 rodrigues_ad_me_jabo.pdf: 1026288 bytes, checksum: c204bcf0ab313f4e57fc58d1ffb4ccf2 (MD5) / Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / A ovinocultura tem se destacado no agronegócio brasileiro, principalmente associada à utilização da raça Santa Inês como raça materna, assim a escolha de animais mais produtivos é fundamental para o sucesso do empreendimento. Com o objetivo de verificar se ovelhas da raça Santa Inês menos suscetíveis às diferentes situações de manejo consideradas estressantes seriam as mais produtivas conduziu-se experimento com 48 animais, avaliados do nascimento dos cordeiros até um mês após desmame. Foram realizadas três imposições de estresse: administração de ACTH, desmame e primeira ordenha. Para administração de ACTH e estresse de primeira ordenha, valores mais altos nos níveis plasmáticos de cortisol foram verificados cerca de uma hora após a imposição dos fatores de estresse e, cerca de seis horas depois, os níveis basais foram restabelecidos, porém, os níveis de cortisol após o desmame continuaram elevados até seis horas após sua imposição. As frequências dos comportamentos LIMP, ING e MAMAR foram influenciadas negativamente pelos maiores níveis de cortisol verificados no desafio “ACTH”. A produção de leite teve pico na segunda quinzena de lactação e os valores percentuais de extrato seco, gordura, lactose, minerais e proteína aumentaram ao longo do período. Durante o período de aleitamento dos cordeiros, a produção de leite das ovelhas foi influenciada pelo maior nível de cortisol plasmático verificado no desafio “ACTH”. Animais com níveis plasmáticos de cortisol mais altos apresentaram resultados inferiores aos de animais com níveis mais baixos / The sheep breeding is having a gain in Brazilian agribusiness mainly the one associated to Santa Ines breed as maternal line, and the choice of more productive animals is fundamental to the business success. The aim of this research was to verify if Santa Ines ewes less susceptible to the different management conditions, considered as stress factors, would be more productive. The experiment was conducted with 48 animals evaluated since the lambs birth up to one month after the wean of the lambs. Three conditions of stress were imposed: standard physiological stress through administration of ACTH, wean and first milking. The ACTH administration and first milking stress induced higher values of plasmatic cortisol one hour after application of stress, and six hours later, the basal levels were re-established. The cortisol levels after wean remained high six hours after stress imposition. The frequencies of behaviors clean up, ingestion and suckle were influenced negatively by the high levels of cortisol verified on the ACTH challenge. The milk production presented one peak in the second fortnight of lactation and the percentual values of dry extract, fat, lactose, minerals and protein increased during the period. During the lambing nursing period, the milk production was influenced by the highest level of plasmatic cortisol, verified in the ACTH stress. Ewes with high levels of plasmatic cortisol present lower results than the animals with smaller cortisol

No description available.

Ultrasound technology allows in vivo estimation of carcass composition. Successful genetic evaluation of ultrasonic measures depends upon technician certification guidelines and a viable common-endpoint adjustment strategy for field data. Four technicians and three image interpreters ultrasonically evaluated 172 lambs to determine accuracy and repeatability of loin eye area (LEA), backfat thickness (BF), and body wall thickness (BW) estimations. Correlations between ultrasonic and carcass measurements were 0.66, 0.78, and 0.73 for LEA, BF, and BW, respectively. Performance was similar among technicians and interpreters. Mean bias ranged from -1.30 to -2.66 cm2, -0.12 to -0.17 cm, and 0.14 to -0.03 cm, for LEA, BF, and BW, respectively; prediction standard errors ranged from 1.86 to 2.22 cm2, 0.12 to 0.14 cm, and 0.35 to 0.38 cm, respectively. Repeatability standard errors ranged from 1.61 to 2.45 cm2, 0.07 to 0.11 cm, and 0.36 to 0.42 cm for LEA, BF, and BW, respectively. Changes in ultrasonic measurements were evaluated using seven serial scans on 24 growing Suffolk ram lambs. All equations had similar goodness of fit. Equations were tested on other populations, including similarly-managed rams across breeds and years and ewe lambs fed for slower gain. Correlations between predicted and actual measures ranged from 0.78 to 0.87 for BF and 0.66 to 0.93 for LEA in winter-born rams, were only slightly lower in fall-born rams, and ranged from 0.72 to 0.74 for BF and 0.54 to 0.76 for LEA in ewe lambs. Of the equations tested, linear and allometric forms appear best for general use. / Master of Science

Trees in silvopastures may provide forage-livestock systems with multiple goods and services, including shade, shelter, and browse. Reports of forage and animal productivity from these systems indicate that, in some cases, animal gains are similar or better despite lower forage yield. The relationship between grazing system, body temperature, grazing behavior, and animal performance was explored in this study. Black walnut and honeylocust-based silvopasture systems were compared with open pastures in a randomized complete block design (r = 3) over three summers. Pastures were rotationally stocked with 5-7 lambs depending on forage availability. Lambs were weighed every four weeks. Behavior measures were recorded within a replicate within a week, and these measures were taken sequentially within three experimental periods. Ewe lambs (n = 3) were equipped with a vaginal temperature sensor (3 days) and an audio recording device (1 day) to detect prehension events. Cameras documented lamb behavior every 60 seconds. Forage measurements taken with a rising plate meter indicated greater productivity in the honeylocust silvopasture (5020 ± 30 kg · ha⁻¹ ) compared to the open pasture (4930 ± 30 kg · ha⁻¹ ; P = 0.0281), though forage availability in the black walnut silvopastures (3560 ± 30 kg · ha⁻¹ ) was lower than within the other treatments (P < 0.0001). There was no difference in animal gains between systems (P ≥ 0.4813), though gains were highest in the honeylocust silvopastures (25.6 ± 3.4 kg · period⁻¹ ), followed by the gains of the black walnut silvopastures (22.3 ± 3.4 kg · period⁻¹ ), and the gains of the open pastures (22.2 ± 3.4 kg · period- 1 ). Lambs in silvopastures spent more time lying down than animals in the open pastures (P ≤ 0.01), while lambs in the open spent more than two hours longer each day standing (P < 0.0001). During the hottest part of the day, ewes in the open pasture were 0.4 °C hotter than ewes in the black walnut silvopastures (P ≤ 0.0202). Lambs in the black walnut silvopastures grazed more (488 ± 14 minutes · day⁻¹ ) than lambs in the honeylocust silvopastures (438 ± 15 minutes · day⁻¹ ; P = 0.0192) and the open pastures (417 ± 14 minutes · day⁻¹ ; P = 0.0009), with no difference between the latter two systems (P = 0.3073). There was no difference in daily bites taken (P ≥ 0.7222), though lambs in the silvopastures grazed more frequently than lambs in the open pastures. In one six week winter grazing study, animal performance in the honeylocust silvopastures was compared with the productivity of lambs grazing the open pastures and the black walnut silvopastures. The objective of this study was to determine the effect of these pods on lamb growth when animals grazed stockpiled tall fescue (Schedonorus arundinaceus). Preand post-graze forage mass was estimated with a double sampling technique using a rising plate meter. Treatment pastures were rotationally stocked with three (walnut) or six lambs per experimental unit depending on forage availability. Fescue grab samples were collected every other rotation. Crude protein (CP), neutral detergent fiber (NDF), acid detergent fiber (ADF), and total digestible nutrients (TDN) were estimated with a robust equation using NIR spectroscopy. Pre- and post-graze pod mass per hectare was estimated using randomly placed quadrats. Lambs were naïve to pods and did not readily consume the fodder until four weeks into the trial, and the methods for estimating pod intake were not sufficient to detect pod differences in pre- and post-graze pod mass. Forage availability in the honeylocust silvopastures (5130 ± 90 kg · ha⁻¹ ) and open pastures (5050 ± 90 kg · ha⁻¹ ; P=0.7580) was greater (P < 0.0001) than forage availability in the black walnut silvopastures (3790 ± 90 kg · ha⁻¹ ). Treatment had no effect (P = 0.3763) on average daily gains across the six weeks of the study. However, lambs within the honeylocust silvopastures had greater (P = 0.0251) average daily gains in the final period (0.12 ± 0.02 kg · day⁻¹ ) than lambs within the open pastures (0 ± 0.02 kg · day⁻¹ ), and lambs were observed consuming the pods. These data suggest that honeylocust pods may support greater gains of lambs, but that previous exposure and longer study periods in pasture settings may be necessary to see their nutritional benefit when grazing high quality forages. / Ph. D.

Résumé : La surveillance de l’intégrité des structures (Structural Health Monitoring - SHM) est une nouvelle technologie, et comme toute nouvelle avancée technologique, elle n’a pas encore réalisé son plein potentiel. Le SHM s’appuie sur des avancées dans plusieurs disciplines, dont l’évaluation non-desctructive, les matériaux intelligents, et les capteurs et actionneurs intégrés. Une des disciplines qui permet son déploiement est la simulation numérique. Le SHM englobe une variété de techniques basées sur la génération d’ondes vibratoires et d’ondes ultrasonores guidées. L’utilisation d’ondes guidées offre en particulier une vaste gamme d’avantages. Le défi majeur associé à la pleine utilisation de la simulation numérique dans la conception d’un système SHM basé sur l’utilisation d’ondes guidées réside dans les ressources de calcul requises pour une simulation précise. La principale raison pour ces exigences est la dispersion induite par la discrétisation numérique, tel qu’indiqué dans la littérature. La méthodes des éléments spectraux (SEM) est une variante de la p-version de la méthode des éléments finis (FEM) qui offre certains outils pour solutionner le problème des erreurs de dispersion, mais la littérature souffre toujours d’une lacune dans l’étude systématique des erreurs de dispersion numérique et de sa dépendance sur les paramètres de simulation. Le présent ouvrage tente de combler cette lacune pour les théories d’ingénierie en vibrations. Il présente d’abord le développement de la formulation des éléments spectraux pour différentes théories d’ingénierie pertinentes pour la propagation des ondes vibratoires dans différents types de structures, comme des tiges et des plaques. Puis, une nouvelle technique pour le calcul des erreurs de dispersion numériques est présentée et appliquée systématiquement dans le but d’évaluer la dispersion numérique induite en termes d’erreurs dans les vitesses de propagation. Cette technique est utilisable pour les différentes formes de propagation des ondes vibratoires dans les éléments structuraux visés dans la présente thèse afin d’évaluer quantitativement les exigences de précision en termes de paramètres de maillage. Les ondes de Lamb constituent un cas particulier de la déformation plane des ondes élastiques, en raison de la présence des doubles frontières à traction libre qui couplent les ondes longitudinales et de cisaillement et qui conduisent à une infinité de modes propagatifs qui sont dispersifs par nature. La simulation des ondes de Lamb n’a pas fait l’objet d’analyse systématique de la dispersion numérique dans la littérature autant pour la SEM que la FEM. Nous rapportons ici pour la première fois les résultats de l’analyse de dispersion numérique pour la propagation des ondes Lamb. Pour toutes les analyses de dispersion numérique présentées ici, l’analyse a été effectuée à˘ala fois dans le domaine fréquentiel et dans le domaine temporel. En se basant sur la nouvelle compréhension des effets de discrétisation numérique de la propagation des ondes guidées, nous étudions l’application de la SEM à la simulation numérique pour des applications de conception en SHM. Pour ce faire, l’excitation piézoélectrique est développée, et une nouvelle technique de condensation statique est développée et mise en œuvre pour les équations de la matrice semi-discrète, qui élimine le besoin de solution itérative, ainsi surnommée fortement couplée ou entièrement couplée. Cet élément piézoélectrique précis est ensuite utilisé pour étudier en détails les subtilités de la conception d’un système SHM en mettant l’accent sur la propagation des ondes de Lamb. Afin d’éviter la contamination des résultats par les réflexions sur les bords une nouvelle forme particulière d’élément absorbant a été développée et mise en œuvre. Les résultats de simulation dans le domaine fréquentiel jettent un éclairage nouveau sur les limites des modèles théoriques actuels pour l’excitation des ondes de Lamb par piézoélectriques. L’excitation par un élément piézoélectrique couplé est ensuite entièrement simulée dans le domaine temporel, et les résultats de simulation sont validés par deux cas de mesures expérimentales ainsi que par la simulation classique avec des éléments finis en utilisant le logiciel commercial ANSYS. // Abstract : Structural health monitoring (SHM) is a novel technology, and like any new technological advancement it has yet not realized its full potential. It builds on advancements in several disciplines including nondestructive evaluation, smart materials, and embedded sensors and actuators. One of the enabling disciplines is the numerical simulation. SHM encompasses a variety of techniques, vibration based, impedance and guided ultrasonic waves. Guided waves offers a wide repertoire of advantages. The major challenge facing the full utilization of the numerical simulation in designing a viable guided waves based SHM System is the formidable computational requirements for accurate simulation. The main reason for these requirements is the dispersion induced by numerical discretization as explained in the literature review. The spectral element (SEM) is a variant of the p-version finite element (FEM) that offers certain remedies to the numerical dispersion errors problem, yet it lacks a systematic study of the numerical dispersion errors and its dependence on the meshing parameters. The present work attempts to fill that gap for engineering theories. It starts by developing the formulation of the spectral element for different relevant engineering theories for guided waves propagation in various structural elements, like rods and plates. Then, extending the utility of a novel technique for computing the numerical dispersion errors, we systematically apply it in order to evaluate the numerically induced dispersion in terms of errors in the propagation speeds. This technique is employed for the various forms of guided waves propagation in structural elements covered in the present thesis in order to quantitatively assess the accuracy requirements in terms of the meshing parameters. The Lamb guided waves constitute a special case of the plane strain elastic waves, that is due to the presence of the double traction free boundaries, couple in the section plane and this coupling leads to an infinitude of propagating modes that are dispersive in nature. Lamb waves simulation have not been a subject of numerical dispersion analysis in the open literature neither for SEM nor FEM for that matter. We report here for the first time the numerical dispersion analysis results for Lamb waves propagation. For all the numerical dispersion analysis presented here, the analysis was done for both the frequency domain and time domain analysis. Based on the established understanding of the numerical discretization effects on the guided waves propagation, we utilize this knowledge to study the application of SEM to SHM simulations. In order to do so the piezoelectric excitation is developed, and a new static condensation technique is developed for the semidiscrete matrix equations, that eliminate the need for iterative solution, thus dubbed strongly coupled or fully coupled implementation. This accurate piezoelectric element are then used to study in details the intricacies of the design of an SHM system with specific emphasis on the Lamb waves propagation. In order to avoid the contamination of the results by the reflections from the edges a new special form of absorbing boundary was developed and implemented. The Simulation results in the frequency domain illuminated the limitations of the current theoretical models for piezoelectric excitation of Lamb waves. The piezoelectric excitation of a fully coupled element is then simulated in the time domain, and the results of simulation was verified against two cases of experimental measurements as well as conventional finite element simulation using the commercial software ANSYS.

In this thesis ultrasonic Lamb wave measurements are performed to detect material nonlinearity in aluminum sheets. When a Lamb wave propagates, higher harmonic wave fields are generated and under certain conditions the second harmonic is cumulative. When these conditions hold the Lamb waves are serviceable for material nonlinearity measurements. For generation, a wedge transducer combination is used. The detection of the Lamb wave are performed with either a laser interferometer or a second wedge transducer combination and the results are benchmarked. A short time Fourier transformation (STFT) is applied to the detected signal to extract the amplitudes of the first and second harmonics. A relative ratio of the first and second harmonics is deduced from nonlinear wave theory to assign the nonlinearity of the material. To verify the capability of the measurement setup and to show that cumulative second harmonics are generated, measurements for different propagation distances are performed. Further measurements on plasticly deformed specimens are carried out to examine the change of the material nonlinearity as a function of plasticity.