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Malyarenko, Eugene V. "Lamb wave diffraction tomography." W&M ScholarWorks, 2000. https://scholarworks.wm.edu/etd/1539623991.
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As the worldwide aviation fleet continues to age, methods for accurately predicting the presence of structural flaws, such as hidden corrosion and disbonds, that compromise air worthiness become increasingly necessary. Ultrasonic guided waves, Lamb waves, allow large sections of aircraft structures to be rapidly inspected. However, extracting quantitative information from Lamb wave data has always involved highly trained personnel with a detailed knowledge of mechanical waveguide physics. In addition, human inspection process tends to be highly subjective, slow and prone to errors. The only practical alternative to traditional inspection routine is a software expert system capable of interpreting data with minimum error and maximum speed and reliability. Such a system would use the laws of guided wave propagation and material parameters to help signal processing algorithms automatically extract information from digitized waveforms. This work discusses several practical approaches to building such an expert system.;The next step in the inspection process is data interpretation, and imaging is the most natural way to represent two-dimensional structures. Unlike conventional ultrasonic C-scan imaging that requires access to the whole inspected area, tomographic algorithms work with data collected over the perimeter of the sample. Combined with the ability of Lamb waves to travel over large distances, tomography becomes the method of choice for solving NDE problems. This work explores different tomographic reconstruction techniques to graphically represent the Lamb wave data in quantitative maps that can be easily interpreted by technicians. Because the velocity of Lamb waves depends on the thickness, the traveltimes of the fundamental modes can be converted into a thickness map of the inspected region. Lamb waves cannot penetrate through holes and other strongly scattering defects and the assumption of straight wave paths, essential for many tomographic algorithms, fails. Diffraction tomography is a way to incorporate scattering effects into tomographic algorithms in order to improve image quality and resolution. This work describes the iterative reconstruction procedure developed for the Lamb Wave tomography and allowing for ray bending correction for imaging of moderately scattering objects.
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Prego, Borges Jose Luis. "Lamb: a simulation tool for air-coupled lamb wave based ultrasonic NDE systems." Doctoral thesis, Universitat Politècnica de Catalunya, 2010. http://hdl.handle.net/10803/6376.
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La técnica de las ondas de Lamb acopladas por aire representa un importante avance en el área de los Ensayos No Destructivos (END) de materiales laminares.Sin embargo la compleja naturaleza de las vibraciones mecánicas encontradas en acústica, hacen que el análisis y el estudio de esta área del conocimiento sea un tema muy complejo. De allí que la posibilidad de contar con una herramienta de simulación de software que permita la evaluación y prueba de diferentes configuraciones de excitación y recepción acústica utilizando la flexibilidad de un modelo de computadora sea de una gran utilidad y ayuda.
El objetivo de la presente tesis es proveer al área de los END con un software de simulación gratuito: The LAMB Matlab® toolbox basado en el modelo del software libre de la GNU.
El software es capaz de simular el comportamiento de sistemas de END basados en ondas de Lamb acopladas por aire en láminas isótropas simples utilizando transductores tipo array.
El programa se basa en un arreglo tipo C-scan de un sistema de END y está compuesto por tres bloques principales: 1) Excitación, 2) Propagación y 3) Recepción.
La verificación individual del funcionamiento de dichos módulos se presenta a lo largo de la tesis mediante una serie de comparaciones entre simulaciones y datos experimentales provenientes de diferentes pruebas. Por otro lado, la validación del programa completo se llevo a cabo por medio de experimentos en láminas de cobre y aluminio; utilizando un sistema real de END por ondas de Lamb acopladas en aire mediante arrays cóncavos.
La influencia negativa en el desempeño general de dicho sistema de END real basado en este tipo de transductores se comprobó efectivamente mediante el simulador desarrollado. Esto se debió fundamentalmente al efecto de directividad de los sensores individuales en los transductores y a la simetría cóncava de los arrays.
Para emular este comportamiento la tesis presenta un modelo geométrico bidimensional simple de un filtro espacial, junto a las simulaciones de un nuevo tipo de array plano propuesto.
El programa desarrollado comprobó así mismo la naturaleza coherente de los campos acústicos emitidos en aire por las láminas sujetas a vibraciones de Lamb. Esto se realizó mediante la implementación de un conformador de haz simple de suma y demora; constituyéndose así la etapa inicial de procesamiento de señal del bloque de recepción del programa.
El objetivo principal del presente trabajo fue contribuir con un modelo operativo de simulación y prueba de nuevos diseños de arrays e implementación de estrategias de procesado de señal útiles en sistemas de END basados en ondas de Lamb acopladas por aire.
Finalmente, si bien el objetivo de la calibración del programa no se pudo conseguir; si se logró efectivamente un notable grado de similitud con un sistema de END real.
Air-coupled ultrasonic Lamb waves represent an important advance in Non- Destructive Testing and Evaluation (NDT & NDE) techniques of plate materials and structures. Examples of these advances are the characterization and quality assessment of laminate materials in manufacturing processes, the location of damaged parts in aircrafts and structure monitoring in the aerospace industry.
However the rich and complex nature of mechanical vibrations encountered in acoustics make the subject of analysis and study of these systems a very complex task. Therefore a simulation tool that permits the evaluation and testing of different configuration scenarios using the flexibility of a computer model is an invaluable aid and advantage.
The objective of this thesis is to provide the field of NDT with free open source software i.e. the LAMB Matlabrtoolbox. The toolbox is capable of simulating the behaviour of Lamb wave based NDE systems for single ideal isotropic laminates using air-coupled ultrasonic arrays. The programme usesa pitch-catch type of a Cscan NDE arrangement and is composed of three integrated sections each individually modelling a feature in the system: 1) Excitation, 2) Propagation, and 3) Reception.
For assessment of the individual modules of the toolbox the thesis presents comparisons between each section simulations and the data obtained from different acoustic experiments. The validation of the complete simulator was carried out by evaluation tests on the copper and aluminium plates by use of a real hardware prototype of a Lamb wave based NDE system with aircoupled concave arrays.
The negative impact on the performance of the real air-coupled NDE systembased on concave arrays was effectively confirmed by the programme. This was produced by the inherent directivity of the individual sensors as well as their concave arrangement. To emulate this behaviour the thesis introduces a simple two-dimensional geometric model for the inclusion of the spatial filtering effect of the sensors plus a group of simulations for a new proposed air-coupled plane array transducer.
The software also verified the spatial coherent nature of the Lamb wave fields emitted by a plate in air. This was demonstrated by the implementation of a delay and sum beamformer to constitute an initial signal processing stage in the reception section.
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Robinson, Brenda Lee. "Influence of colostrum from safflower supplemented ewes on lamb cold tolerance and lamb growth." Thesis, Montana State University, 2008. http://etd.lib.montana.edu/etd/2008/robinson/RobinsonB1208.pdf.
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Five hundred, ninety-seven and 643 white face range ewes were used in a 2 year study, respectively, in a 3-way factorial arrangement to determine effect of supplemental linoleic oil on lamb serum metabolites, thermogenesis and lamb growth. During the last 45 ± 4 days of gestation ewes were group fed a daily supplement of either 0.23 kg•ewe-1•d-1 whole safflower seed (SS) or 0.34 kg•ewe-1•d-1 whole barley (C). Colostrum was collected from each supplement treatment and pooled according to treatment. At parturition, twin born lambs received either SS or C pooled colostrum. One h postpartum, lambs were placed in a 0°C dry cold chamber for 30 min. and lamb rectal temperature was recorded at one min intervals. Blood samples were taken prior to and after cold exposure. Lamb weights were taken at birth, turnout and weaning for growth. There was no difference (P > 0.10) in body temperatures between lambs born to ewes supplemented with SS vs. C or between lambs given pooled colostrum form SS or C supplemented ewes. At 0 minutes lambs born to SS supplemented ewes had lower glucose (P = 0.05), total protein (P = 0.05) and NEFA (P = 0.003) and higher BUN (P = 0.03) than lambs from C supplemented ewes. Lambs from SS supplemented ewes had lower NEFA (P = 0.01) after cold exposure (30 minutes). Total protein concentration was similar in year 1 but lower (P < 0.01) in year 2. Concentrations of aGP were higher in lambs from SS supplemented ewes at both 0 and 30 min in year 1. Lambs from SS ewes had higher (P < 0.01) blood aGP levels at both 0 and 30 min in year 1 than in year 2. No differences (P > 0.30) were detected between lambs from SS ewes vs. C for changes in any blood metabolites measured during cold stress period. No differences (P > 0.12) were detected for average date of birth, number of lambs born, number of lambs present at turnout and weaning or for weight of lambs at turnout or weaning for ewes receiving either SS or C supplements.
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Benjamin, Rishon Robert. "Silence of the lamb waves." Thesis, Massachusetts Institute of Technology, 2017. http://hdl.handle.net/1721.1/111503.
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Thesis: S.M., Massachusetts Institute of Technology, Computation for Design and Optimization Program, 2017.Cataloged from PDF version of thesis.
Includes bibliographical references (pages 101-104).
Roll-to-Roll (R2R) manufacturing has seen great interest in the recent decade due to the proliferation of personalized and wearable devices for monitoring a variety of biometrics. Given the sensitive nature of the potential applications of these sensors, the throughput of manufacturing due to increased demand, and the scale of the electrical components being manufactured, R2R flexible electronics manufacturing technologies require new sensing and measurement capabilities for defect detection and process control. The work presented herein investigates the use of ultrasound, specifically Lamb and longitudinal waves, as a sensing modality and measurement technique for thin film R2R manufacturing substrates. Contact (transducer-based) and non-contact (photoacoustic) generation methods along with deterministic and probabilistic tomographic reconstruction algorithms were implemented evaluate their suitability for non-destructive evaluation (NDE) and in-line control of surface additions of 76[mu]m aluminum and polyethylene terephthalate (PET) films. The ultrasonic waves were used to ascertain properties of these substrates such as the thickness of substrate, applied load, presence of defects (holes/cracks), size of defects, presence of surface features (fluid drops, multi-layer structures), and nature of surface features (differing chemistries). In addition, surface features alter the behavior of sound waves in the presence of such features. These surface features may then be imaged to create tomographic maps. The results presented show that, currently, a quasi-contact acoustic generation scheme can be used to successfully image defects and surface features on the order of -1mm. Furthermore, the algorithm is able to distinguish qualitatively between surface features of differing physiochemical properties. The authors hope that the information collected from this thesis will be part of a rich data set that can contribute to advanced machine-learning frameworks for predictive maintenance, failure, and process control analysis for the R2R process.
by Rishon Robert Benjamin.
S.M.
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Stanford, Kim. "Prediction of lamb carcass composition and classification of Canadian lambs by saleable meat yield." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp04/nq29113.pdf.
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Turnbull, Elwin Donald, of Western Sydney Hawkesbury University, and Faculty of Agriculture and Rural Development. "Developing the Australian lamb industry using action research." THESIS_FARD_XXX_Turnball_E.xml, 1993. http://handle.uws.edu.au:8081/1959.7/84.
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This document reports on the rationale for and results of using action research in order to facilitate development of the Australian lamb industry. The contexts of this research were: a lamb industry that had declining consumption; producers were slow to change to the production of new style of lamb which more closely aligned with consumer trends towards lower fat and convenience foods; and major changes in research funding criteria, towards projects with measurable impacts upon industries. The perspective taken in this research was that the production and marketing of lamb is essentially a human activity. Action research was effective in providing a methodology for working with extension and research officers using focus group meetings with lamb producers in South Eastern Australia. The key activity was the creation of an environment for a rich social discourse between industry people, focussing on establishing suitable processes and relationships within the industry. Valuable resources consisting of current industry skills, knowledge and institutions were utilised through this project for the benefit of the industry. This project illustrated a role for action research as an effective way of facilitating learning and communication in the lamb industry. The impact of the project was limited because the activities were confined to the production end of the marketing channel. The research helped the author to develop a deeper understanding of participatory action research and the close linkage between learning and self image. The experience of conducting the research validated the importance of the group dynamic in action research and the difficulty that individuals and groups have in matching actions with espoused theoryMaster of Science (Hons)
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Christofor-Ganev, Yvonne. "Charles und Mary Lambs "Tales from Shakespeare" /." Frankfurt am Main : P. Lang, 1995. http://catalogue.bnf.fr/ark:/12148/cb37702970p.
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Garza, Horacio III. "The Effects of Age, Sex, and Hot Carcass Weight on Cooked Lamb Flavor and Off Flavor in Four Muscle Cuts." The Ohio State University, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=osu1511949373145599.
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Nebel, Tobias. "The Lamb Shift in Muonic Hydrogen." Diss., lmu, 2010. http://nbn-resolving.de/urn:nbn:de:bvb:19-120947.
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Rüdiger, Benz. "Localization of notches with lamb waves." Thesis, Georgia Institute of Technology, 2002. http://hdl.handle.net/1853/21510.
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Shi, Yijun 1970. "Analysis of optimum Lamb wave tuning." Thesis, Massachusetts Institute of Technology, 2002. http://hdl.handle.net/1721.1/8296.
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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Civil and Environmental Engineering, 2002.Includes bibliographical references (p. 243-251).
Guided waves are of enormous interest in the nondestructive evaluation of thin-walled structures and layered media. Due to their dispersive and multi-modal nature, it is desirable to tune the waves by discriminating one mode from the others. The objectives of this thesis are (1) to develop schemes and procedures for Lamb wave tuning, (2) to develop tools for understanding and analyzing the mechanism of various tuning techniques, and (3) to provide suggestions and guidelines for selecting optimum tuning parameters. In order to remedy the inherent problems of traditional tuning techniques using angle wedge and comb transducers (such as the inability to tune the modes with low phase velocities, and the inability to control the propagation direction of tuned waves), a novel dynamic phase tuning concept using phased arrays is proposed. In this approach, the constructive interference of desired modes is achieved by properly adjusting the time delays. As an extension to this concept, the synthetic phase tuning (SPT) scheme is introduced, in which the tuning effect is achieved by constructing virtual waves. The effectiveness of SPT against other techniques is experimentally demonstrated, which shows its feasibility. To understand the mechanism of tuning, an analytical model is developed to study transient waves, based on the Fourier integral transform method. The excitation conditions for both angle wedge and array transducers are taken into account. The surface displacements of individual modes and their temporal and spatial Fourier spectrum are derived and used to study the tuning behavior. The analytical results are compared with the experimental results as well as the numerical results obtained from the finite element simulation studies.
(cont.) In dealing with broadband signals, laser generated Lamb waves are investigated. Both line and circular source loading models are developed to study the behavior in the ablation regime. The predicted waveforms and dispersion curves are in good agreement with the experimental results. Based on the same SPT scheme, virtually-tuned waves are constructed by processing a set of broadband signals. Finally, Lamb waves in a transversely isotropic composite plate are investigated. Although the analysis is limited only to the waves propagating in the principal directions, it could serve as the basis for future work on tuning of Lamb waves in composites. It is concluded from this thesis that the SPT method enjoys advantages over other methods including its low operation cost, ability to tune the. modes of low phase velocities, and capability to control the propagation direction of tuned waves. The analysis of transient waves allows us to examine various tuning scenarios. The investigation of the tuning effectiveness enables us to select optimum modes for the given conditions.
by Yijun Shi.
Ph.D.
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Araujo, Rodrigo Andrade Cavalcanti. "Detecção óptica de onda de Lamb." Instituto Tecnológico de Aeronáutica, 1996. http://www.bd.bibl.ita.br/tde_busca/arquivo.php?codArquivo=1594.
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Esta tese apresenta a análise teórica e experimental da detecção de onda de Lamb em sólido isotrópico, através da utilização de um interferômetro óptico tipo Mach-Zehnder heterodino. Foi desenvolvida uma formulação para analisar a interação acusto-óptica superficial que utiliza a onda de Lamb, levando-se em consideração ambas as componentes de deslocamento acústico geradas pela onda de Lamb. Os resultados dessa análise revelaram que, ao contrário do que é regularmente divulgado na literatura, existem situações onde a difração acusto-óptica decorre também devido à componente horizontal do deslocamento acústico gerado pela onda de Lamb. A formulação desenvolvida também proporciona uma abordagem rigorosa para o estudo das técnicas de detecção síncrona e assíncrona aplicadas à detecção óptica de onda acústica. Os resultados obtidos possibilitam uma compreensão detalhada da dependência das características do sinal elétrico obtido na saída do circuito de detecção, em função da posição do ponto de interação com relação à região de geração da onda de Lamb, bem como da influência da fase e amplitude do oscilador local nas características medidas do espectro do sinal de saída do interferômetro. Na parte experimental, a detecção óptica de onda de Lamb é investigada através da utilização do interferômetro na condição onde o feixe óptico incidente sobre o corpo de prova apresenta diâmetro significativamente menor que o comprimento de onda acústico. As medidas realizadas, utilizando as técnicas de detecção síncrona e travamento de fase, PLL, revelaram o comportamento periódico que o sinal detectado apresenta como função da distância do ponto de interação à região de geração da onda de Lamb. Os resultados experimentais incluem ensaios com onda de Lamb variando harmonicamente como o tempo. Através deles, foi possível determinar a velocidade de fase da onda de Lamb gerado pelo transdutor piezoelétrico.
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Chen, Liling. "Lamb wave propagation in multilayered pipes." Diss., The University of Arizona, 2001. http://hdl.handle.net/10150/290123.
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In this dissertation a characteristic equation has been obtained, in the framework of the linear theory of elasticity, for multilayered pipes; individual layers are made of isotropic elastic solids. A theoretical study of the Lamb wave propagation in multilayered pipes for both axisymmetric and nonaxisymmetric loading is presented. The stress and displacement variations inside the multilayered pipe are theoretically calculated for a number of propagating Lamb modes. The Lamb wave dispersion curves and the curves of frequency versus the ratio of wall thickness to half wave length have been computed for different Lamb modes inside a homogeneous pipe and have been compared with published results. These computations are extended to multilayered pipes.
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Grube, Laura Katherine. "The Effects of Sex, Breed, and Slaughter Weight on Growth, Carcass, and Sensory Characteristics of Lamb." Thesis, North Dakota State University, 2018. https://hdl.handle.net/10365/29216.
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American lambs are often over-finished and lack consistent quality. It has been suggested that the use of intact ram lambs can decrease USDA YG and improve growth efficiency. However, ram lamb carcasses are underutilized because of potential issues, the most crucial being off-flavor development. Our hypothesis for this study is that U.S. producers can take advantage of intact ram lamb growth and performance with no detriment to product quality, as long as lambs are slaughtered before the attainment of puberty. Three breeds (Hampshire, Dorset, and Columbia), three slaughter weights (light, medium, and heavy) and two sexes (rams and wethers) were evaluated. Results indicate that ram lambs can provide a satisfactory eating experience, however, in one of our studies compounding of maturity and slaughtering intact rams increased incidence of off-flavors. It remains undetermined whether the small differences in sensory characteristics would be detectable by everyday consumers.
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Johnson, Stacey Ann. "The influence of early postmortem enhancement and inclusion of dextrose on lamb longissimus tenderness." Columbus, Ohio : Ohio State University, 2009. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1236709470.
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Antognini, Aldo. "The Lamb Shift Experiment in Muonic Hydrogen." Diss., lmu, 2005. http://nbn-resolving.de/urn:nbn:de:bvb:19-50441.
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Fry, Charles Alan. "Measurement of the Lamb shift in muonium." Thesis, University of British Columbia, 1985. http://hdl.handle.net/2429/25785.
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This thesis describes the first measurement of the Lamb shift in n=2 muonium. The muonium atom is a hydrogen-like bound state of two leptons (µ⁺e⁻), both of which are believed to be point-like particles. The point-like nature of the constituent particles simplifies and reduces the uncertainty of the application of quantum electrodynamics (QED) to the calculation of the Lamb shift in the muonium atom. Measurements of the Lamb shift in hydrogen disagree with the predictions of theory by a few standard deviations; however, theoretical predictions also disagree with each other, partly because of difficulties associated with the treatment of the proton structure. Thus a measurement in the muonium system of similar precision to those already made in the hydrogen system will be a valuable test of QED. The present experiment is not intended to test QED. It is an investigation of the methods and techniques necessary to
surmount the difficulties presented by the nature of muonium. The available number of muonium atoms is about 10⁺¹º times less than that of hydrogen used by Lamb in his first measurement. The value obtained for the n=2 muonium Lamb shift 1070⁺¹²₋₁₅ MHz. The uncertainty quoted is statistical at the 68% confidence level. Systematic effects were found to contribute to a further 2 MHz uncertainty.Science, Faculty of
Physics and Astronomy, Department of
Graduate
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Gudex, B. W. "Sireline variation in neonatal lamb cold tolerance." Lincoln University, 2001. http://hdl.handle.net/10182/1055.
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The cost of lamb mortality caused by cold exposure has been estimated at approximately 40 million dollars per year. This value is probably conservative as it does not include the cost due to the reduction in productivity in hypothermic lambs that manage to survive or the cost of reduced selection potential incurred by fewer lambs surviving until selection. The objectives of this research was to investigate whether sire-line variation exists in neonatal lamb cold tolerance and whether polymorphism in the β₃ adrenergic receptor gene can be used as a genetic marker for lamb cold tolerance and lean muscle growth. The influence of the climate, birthweight, age of dam at lambing, gender and birth rank on neonatal lamb cold tolerance was also analysed. Neonatal lamb mortality due to cold exposure was analysed in four field trials that used neonatal lamb morality from cold exposure as a predictor of neonatal lamb cold tolerance. Sire-line variation in neonatal lamb morality was observed in all trials, though it appeared that this effect was largely mediated through sire-line variation in lamb birth weight. Variation in lamb birth weight between birth rank classed was also found to be responsible for the influence of birth rank on neonatal lamb mortality due to cold exposure. The age of dam at lambing and the lamb gender was not observed to influence neonatal lamb mortality due to cold exposure. The sires from the cold tolerance study and the progeny of the lean muscle growth study were genotyped for the β₃ adrenergic receptor locus. Other studies have found evidence that a major gene exists in the catecholamine stimulation of brown adipose thermogenesis and evidence that the β₃-AR gene is a likely candidate. However, this hypothesis and the hypothesis that polymorphism in the β₃-AR gene is also linked to lean muscle growth in lambs was not confirmed in this study. So while it appears that the results were confounded by experimental design, there is evidence that influence of polymorphism in the ovine β₃ AR gene on neonatal lamb mortality and/or lean muscle growth is not sufficient to be considered a major gene effect. The implications of this experiment on the sheep industry and sheep farmers in general are huge. While completely eliminating lamb deaths due to inadequate cold tolerance is impossible, this study shows that large gains in lamb survival could be possible through selective breeding.
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Wyatt, A. C. "'The true Elia' : Charles Lamb and autobiography." Thesis, University of Reading, 1986. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.374026.
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Sugandhi, Mardian Jun 1978. "Optimum tuning of laser-generated Lamb waves." Thesis, Massachusetts Institute of Technology, 2003. http://hdl.handle.net/1721.1/85748.
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Wang, Wei. "Manipulation of Lamb waves with elastic metamaterials." Thesis, Sorbonne université, 2019. http://www.theses.fr/2019SORUS414.
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Nous développons des métamatériaux élastiques à piliers pour manipuler les ondes de Lamb. Dans un premier temps, les propriétés négatives associées aux résonances de flexion, de compression et de torsion dans deux structures constituées de piliers sur un seul côté d’une membrane sont examinées. Nous décrivons deux mécanismes différents des propriétés de double négativité. Le potentiel de ces structures pour la réfraction négative et le cloaking acoustique est démontré. Deuxièmement, nous présentons le transport protégé topologiquement des ondes de Lamb par analogie avec les effets Hall quantiques de spin et de vallée. En réorganisant les structures précédentes en un réseau en nid d'abeille, un cône de Dirac simple et un cône de Dirac double sont introduits. Nous discutons de l’apparition d’états de bord protégés topologiquement par une vallée dans une structure à piliers double face asymétrique. La propagation unidirectionnelle des états de bord est étudiée. De plus, nous considérons un système double face symétrique. Les états de bord protégés topologiquement sur le pseudospin et sur le pseudospin-vallée sont démontrés. Troisièmement, nous proposons une approche pour contrôler activement la transmission de l’onde de Lamb antisymétrique se propageant à travers une ligne infinie de piliers. Deux situations différentes avec les résonances de flexion et de compression respectivement séparées ou superposées sont étudiées. Une force de traction externe et une pression sont appliquées sur les piliers, ce qui permet de les coupler avec les vibrations de flexion et de compression. La transmission est étudiée en fonction de l’amplitude et de la phase relative des sources externesWe develop elastic pillared metamaterials to manipulate Lamb waves. Firstly, the negative properties associated with bending, compression and torsion resonances in two structures consisting of pillars on one side of a thin plate are examined. We describe in details two different mechanisms at the origin of doubly negative property. The potential of these structures for negative refraction of Lamb waves and acoustic cloaking is demonstrated numerically. Secondly, we present the topologically protected transport of Lamb waves by analogy with quantum spin and valley quantum Hall effects. By rearranging the previous structures into a honeycomb network, a single Dirac cone and a double Dirac cone are introduced. We discuss the appearance of topologically valley-protected edge states in an asymmetrical double-sided pillar structure. The unidirectional propagation of edge states on different domain walls is studied. In addition, we consider a symmetrical double-sided system allowing the separation of the symmetric and antisymmetric modes. Combined edge states protected topologically by pseudospin and pseudospin-valley degree of freedom are demonstrated. Third, we propose an approach to actively control the transmission of the antisymmetric Lamb wave propagating through an infinite line of pillars. Two different situations with bending and compression resonances respectively separated or superimposed are studied. External tensile force and pressure are applied to the pillars, which allows them to couple with the bending and compressive vibrations. The transmission is studied as a function of the amplitude and the relative phase of the external sources
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Tang, Bruce S. "Lamb wave propagation in laminated composite plates." Diss., Virginia Polytechnic Institute and State University, 1988. http://hdl.handle.net/10919/80194.
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Low frequency Lamb waves in composite laminates were investigated theoretically and experimentally. To have a general solution for Lamb wave propagation in multilayered composite laminates is not practical due to a large number of boundary conditions needed to be satisfied at the interlaminar interfaces. Various approximate theories have been proposed to model low frequency Lamb wave propagation in composite laminates. In the present study, an approximate solution was derived from an elementary shear deformation plate theory and was shown to work well in the low frequency, long wavelength region.
A simple method, similar in configuration to the acousto-ultrasonic technique, was used to measure Lamb wave phase velocities. Low frequency Lamb waves, usually in the range of 10 kHz to 1 MHz, were generated. Dispersion curves of the lowest symmetric Lamb mode and the lowest antisymmetric Lamb mode were obtained. The experimental data were compared with the results obtained from the approximate solution for the lowest Lamb modes in the low frequency, long wavelength region for a unidirectional laminate, a symmetric cross-ply laminate, a symmetric quasi-isotropic laminate and an aluminum plate. There is good correlation between the data and the results obtained from the approximate solution, which suggests that the lowest Lamb modes are modeled adequately by the present theory in these cases. This experimental procedure of measuring phase velocities can be used to characterize laminated composite plates with and without damage since each material and stacking sequence gives distinct lowest symmetric and antisymmetric curves.
Stiffness reduction of composite laminates caused by damage can be related to the change in Lamb wave propagation speed. Damage in the form of transverse cracks in the 90° plies of a [90/90/90/0], graphite/epoxy laminate reduced the phase velocities of the Lamb modes. The lowest antisymmetric mode is sensitive to stiffness reduction in composite plates. Consequently, axial stiffness reduction in [0/45/0/45/0/45], and [0]₁₂ woven graphite/polyimide composite laminates was monitored by the lowest antisymmetric Lamb mode.Ph. D.
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Brogna, Daniela Maria Rita. "Effect of saponins on lamb meat quality." Doctoral thesis, Università di Catania, 2012. http://hdl.handle.net/10761/1127.
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The purpose of this research was to evaluate the effects of saponins on lamb meat quality. In the first experiment, increasing levels of saponins from Quillaja saponaria L. were supplemented to lambs to evaluate their effects on fatty acid composition and cholesterol content in the muscle longissimus dorsi. In the second experiment, saponin supplementation was given as a single ration or as a choice with tannin to evaluate its effect on lamb meat quality. The lower and higher concentration of C14:1cis-9 in the lamb meat, respectively in the first and the second experiments, suggest a possible effect of these PSCs on delta9-desaturase enzyme activity. Moreover, the low concentartion of furan,2-pentyl and TBARS values in the meat of lamb fed saponin diet suggest an antioxidant effect of saponin against lipid oxidation. Further investigations are necessary to assess the specific role of saponins on meat quality.
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Annett, R. W. "Studies on the effects of the nutrition of ewes during pregnancy on neonatal lamb survival and lamb output at weaning." Thesis, Queen's University Belfast, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.411764.
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Koabaz, Mahmoud. "Contribution à l’étude des ondes de LAMB dans une plaque anisotrope : théorie et expérience." Thesis, Bordeaux 1, 2010. http://www.theses.fr/2010BOR14071/document.
Full textAbstract:
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 théorieThe 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
26
Mills, Catriona. "Infamous imaginings : the novels of Lady Caroline Lamb /." St. Lucia, Qld, 2004. http://www.library.uq.edu.au/pdfserve.php?image=thesisabs/absthe17829.pdf.
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Edwards, Anthony Newton. "The architecture of Edward Buckton Lamb (1805-1869." Thesis, University of Liverpool, 2010. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.539916.
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Oppong-Anane, Kwame. "The following (walking) ability of the neonatal lamb." Title page, table of contents and abstract only, 1991. http://web4.library.adelaide.edu.au/theses/09PH/09pho62.pdf.
Full textAbstract:
Includes bibliographical references (leaves 276-2970. Investigations presented involve 18 hour to 5 day old South Australian merino lambs. Some twin lambs were available for comparative studies. Examines the relationship between the strength of ewe-lamb bond and the lamb's ability to follow the mother, the energy availability and usage in the lamb, particularly for locomotion, and the metabolic and cardiorespiratory responses to locomotion.
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au, R. Jacob@central murdoch edu, and Robin Henry Jacob. "Optimising the concentration of glycogen in lamb meat." Murdoch University, 2003. http://wwwlib.murdoch.edu.au/adt/browse/view/adt-MU20040513.153312.
Full textAbstract:
The lamb industry is actively seeking to improve the quality of lamb meat produced in Australia. Ultimate pH (pHu) is a key determinant of red meat eating quality although this measurement has not been adopted formally by the Australian lamb meat industry. Muscle glycogen concentration is a major determinant of pHu in red meat. This thesis investigates glycogen concentration in lamb muscle and the ultimate pH (pHu) of lamb meat under commercial industry conditions as well as exploring by experimentation, some of the factors that control muscle glycogen concentration in lamb muscle. The results of this work has contributed to an understanding of the significance of high pHu meat to the lamb industry and will assist with developing new management strategies for lambs that avoid low muscle glycogen concentration at the point of slaughter, thus high pHu in meat derived from lambs.
The first part of the study (Experiments 1 and 2) undertook to determine the ranges of muscle glycogen concentration and lamb meat pHu found under commercial conditions and to measure any changes in these parameters associated with consignment of lambs from farm to abattoir and lairage at abattoirs. This study utilised a new biopsy technique that allowed muscle collection from lambs on farm. Some 16 different consignments of lambs and 3 consignments of lactating ewes were intensively monitored on farm and at abattoirs over a range of lairage times. Sensory evaluation tests were done using meat from 6 of these consignments.
The results showed there to be considerable variation between lamb consignments with some consignments having a very high and other consignments having a very low incidence of meat with a high pHu. On balance on farm factors were concluded to have a greater impact on muscle glycogen concentration at slaughter than post farm gate factors. However, there was evidence that muscle glycogen concentrations decreased during the farm curfew and transport period for some consignments so both on farm and post farm gate factors can be important. Characteristically glycogen loss occurred during the farm curfew and transport period in consignments of Merino lambs that had high muscle glycogen concentrations prior to consignment. Holding lambs in lairage caused no negative effects on muscle glycogen concentration although there was some evidence that very short lairage periods may increase meat pHu without causing a change in muscle glycogen concentration. It was concluded from these experiments that the mean muscle glycogen concentration of a group of lambs needs to be greater than 1.5 g/100g on farm in order for the pHu of lamb meat to be less than 5.7.
Subsequent to this industry study, an experiment (Experiment 3) was done to gain an understanding of muscle glycogen concentration as being an integral part of whole body glucose metabolism. This experiment investigated the effects of exercise on a range of different muscles and tissues of lambs including liver, kidney, skin and gastrointestinal tract. Interactions between glycogen concentrations in the liver and muscle with time after exercise showed that glycogen repletion occurred in the liver before muscle tissue. This effect was a unique finding and could explain in part the slow rate of glycogen repletion in muscle tissue that is characteristic for ruminants. Another major finding was an accumulation of glycogen concentration in skin during the recovery period after exercise. It was postulated that this effect may be due to the supply of glucose to glycolytic tissues being continued even when demand for glucose in the skin was low and the capacity to store glycogen in muscle was very high.
Experiment 3 confirmed the existence of a relationship between metabolisable energy (ME) intake and glycogen repletion in muscle tissues and found a slightly different relationship between ME intake and glycogen repletion in the liver tissue of lambs. Muscle glycogen concentration did not change in fasted lambs and the rate of glycogen repletion in muscle after exercise was dependent on ME intake. Differences were observed between different muscles, particularly between M. longissimus thoracis et lumborum (LTL) and all other muscles, in relation to the change in glycogen concentration with time after exercise. Glycogen concentrations changed less rapidly in the LTL than other muscles. Glycogen concentration in the liver was associated negatively with time after exercise in fasted lambs and positively with time after exercise in fed lambs.
Several experiments (Experiments 4, 5 and 6) were conducted to determine the affects of different nutritional factors on muscle glycogen concentration in lambs, both on farm and after commercial slaughter. These studies showed that short term increases in ME intake will increase muscle glycogen concentration to a maximum level over a period of about 7 days (Experiment 4). Diet composition did not affect the change in muscle glycogen concentration associated with an increase in ME intake although results from this experiment (Experiment 5) were not entirely conclusive. There was evidence that the type of feeding and finishing system may influence the susceptibility of muscle glycogen concentration to change during consignment of lambs to slaughter. Results from these experiments demonstrated that a goal for muscle glycogen concentration in lambs on farm of 1.5g/100g is quite achievable with contemporaneous management systems.
Finally this study highlighted the need for further research in a number of key areas in order that muscle glycogen concentration in lambs to be fully understood. In particular, the role of muscle glycogen turnover in relation to muscle glycogen concentration was noted as an area for which further research is warranted.
30
Rutledge, M. P. "Assessing demand for organic lamb using choice modelling." Diss., Lincoln University, 2009. http://hdl.handle.net/10182/1110.
Full textAbstract:
The worldwide market for organic foods is growing fast, but New Zealand meat producers have been slow to respond. Specifically, New Zealand producers have little or no organic lamb products for export or domestic sale. Part of the reason for this hesitancy to meet demand with supply is that the nature of the demand and consumer willingness to pay for the product is not well understood. The purpose of this study is to investigate New Zealand organic food consumers’ attitudes towards organic food and production methods and to evaluate consumer willingness to pay for an organic lamb product. Data for this study was collected using computer aided personal interviewing (CAPI) in supermarkets and speciality stores in Christchurch and Wellington. The study questioned consumers about their consumption habits, attitudes towards organic food and production methods and presented choice modelling scenarios to test willingness to pay for different attributes of lamb. Factor analysis is used to group the 12 attitudinal questions into three factors which were then placed into a two step cluster analysis to create consumer segments. Choice modelling was then used to measure consumer preferences for the tested attributes of lamb. From the factor and cluster analysis three distinct consumer segments were found and labelled as Committed Organic Seekers, Convenience Organic Consumers and Incidental Organic Consumers. These labels reflect each group’s organic consumption habits and attitudes towards organic food. The choice modelling results show that there is a willingness to pay for organic lamb. The three identified consumer groups state they would pay a premium of 61%, 44% and 26% respectively for organic lamb over standard pasture raised lamb. This paper gives an insight into consumer attitudes and preferences towards a product that could provide a way for New Zealand farmers to increase their returns. It contributes to the body of knowledge about the likely consumer profiles of regular consumers of organic food. There are only a few other studies that have attempted to measure consumer attitudes and willingness to pay for organic meat, however, the author is not aware of any published example of a study that has specifically investigated demand for organic lamb anywhere in the world. The study provides information about stated willingness to pay for five different attributes of lamb; this information should be of value in assisting the industry by showing which product offerings are likely to generate the highest sale price.
31
Hillmann, Ranforth Cy. "The Lamb of God in John 1:29." Theological Research Exchange Network (TREN), 1988. http://www.tren.com.
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Andrews, David C. "Breathing control and thermoregulation in the developing lamb." Thesis, Oxford Brookes University, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.359674.
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Konstantinidis, Georgios. "Structural health monitoring of plates using lamb waves." Thesis, University of Bristol, 2008. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.495779.
Full textAbstract:
It is desirable for any structural health monitoring (SHM) system to achieve maximum sensitivity with minimum sensor density. This may be accomplished using guided waves. The structural health monitoring system described herein is based on the excitation and reception of guided waves using piezoelectric elements as sensors. One of the main challenges faced is that in all but the most simple structures the wave interactions become too complex for the time domain signals to be interpreted directly.
34
Anderson, Jennifer M. L. "An evaluation of entire males for lamb production." Thesis, University of Newcastle Upon Tyne, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.481467.
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Gate, John James. "The regulation of growth in the postnatal lamb." Thesis, University of Reading, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.308033.
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Rimal, Nischal. "Impact Localization Using Lamb Wave and Spiral FSAT." University of Toledo / OhioLINK, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=toledo1388672483.
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Alleyne, David N. "Nondestructive testing of plates using ultrasonic Lamb waves." Online version, 1991. http://ethos.bl.uk/OrderDetails.do?did=1&uin=uk.bl.ethos.263143.
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Jacob, Robin Henry. "Optimising the concentration of glycogen in lamb meat." Thesis, Jacob, Robin Henry (2003) Optimising the concentration of glycogen in lamb meat. PhD thesis, Murdoch University, 2003. https://researchrepository.murdoch.edu.au/id/eprint/110/.
Full textAbstract:
The lamb industry is actively seeking to improve the quality of lamb meat produced in Australia. Ultimate pH (pHu) is a key determinant of red meat eating quality although this measurement has not been adopted formally by the Australian lamb meat industry. Muscle glycogen concentration is a major determinant of pHu in red meat. This thesis investigates glycogen concentration in lamb muscle and the ultimate pH (pHu) of lamb meat under commercial industry conditions as well as exploring by experimentation, some of the factors that control muscle glycogen concentration in lamb muscle. The results of this work has contributed to an understanding of the significance of high pHu meat to the lamb industry and will assist with developing new management strategies for lambs that avoid low muscle glycogen concentration at the point of slaughter, thus high pHu in meat derived from lambs.
The first part of the study (Experiments 1 and 2) undertook to determine the ranges of muscle glycogen concentration and lamb meat pHu found under commercial conditions and to measure any changes in these parameters associated with consignment of lambs from farm to abattoir and lairage at abattoirs. This study utilised a new biopsy technique that allowed muscle collection from lambs on farm. Some 16 different consignments of lambs and 3 consignments of lactating ewes were intensively monitored on farm and at abattoirs over a range of lairage times. Sensory evaluation tests were done using meat from 6 of these consignments.
The results showed there to be considerable variation between lamb consignments with some consignments having a very high and other consignments having a very low incidence of meat with a high pHu. On balance 'on farm' factors were concluded to have a greater impact on muscle glycogen concentration at slaughter than 'post farm gate' factors. However, there was evidence that muscle glycogen concentrations decreased during the farm curfew and transport period for some consignments so both 'on farm' and 'post farm gate factors' can be important. Characteristically glycogen loss occurred during the farm curfew and transport period in consignments of Merino lambs that had high muscle glycogen concentrations prior to consignment. Holding lambs in lairage caused no negative effects on muscle glycogen concentration although there was some evidence that very short lairage periods may increase meat pHu without causing a change in muscle glycogen concentration. It was concluded from these experiments that the mean muscle glycogen concentration of a group of lambs needs to be greater than 1.5 g/100g on farm in order for the pHu of lamb meat to be less than 5.7.
Subsequent to this industry study, an experiment (Experiment 3) was done to gain an understanding of muscle glycogen concentration as being an integral part of whole body glucose metabolism. This experiment investigated the effects of exercise on a range of different muscles and tissues of lambs including liver, kidney, skin and gastrointestinal tract. Interactions between glycogen concentrations in the liver and muscle with time after exercise showed that glycogen repletion occurred in the liver before muscle tissue. This effect was a unique finding and could explain in part the slow rate of glycogen repletion in muscle tissue that is characteristic for ruminants. Another major finding was an accumulation of glycogen concentration in skin during the recovery period after exercise. It was postulated that this effect may be due to the supply of glucose to glycolytic tissues being continued even when demand for glucose in the skin was low and the capacity to store glycogen in muscle was very high.
Experiment 3 confirmed the existence of a relationship between metabolisable energy (ME) intake and glycogen repletion in muscle tissues and found a slightly different relationship between ME intake and glycogen repletion in the liver tissue of lambs. Muscle glycogen concentration did not change in fasted lambs and the rate of glycogen repletion in muscle after exercise was dependent on ME intake. Differences were observed between different muscles, particularly between M. longissimus thoracis et lumborum (LTL) and all other muscles, in relation to the change in glycogen concentration with time after exercise. Glycogen concentrations changed less rapidly in the LTL than other muscles. Glycogen concentration in the liver was associated negatively with time after exercise in fasted lambs and positively with time after exercise in fed lambs.
Several experiments (Experiments 4, 5 and 6) were conducted to determine the affects of different nutritional factors on muscle glycogen concentration in lambs, both on farm and after commercial slaughter. These studies showed that short term increases in ME intake will increase muscle glycogen concentration to a maximum level over a period of about 7 days (Experiment 4). Diet composition did not affect the change in muscle glycogen concentration associated with an increase in ME intake although results from this experiment (Experiment 5) were not entirely conclusive. There was evidence that the type of feeding and finishing system may influence the susceptibility of muscle glycogen concentration to change during consignment of lambs to slaughter. Results from these experiments demonstrated that a goal for muscle glycogen concentration in lambs on farm of 1.5g/100g is quite achievable with contemporaneous management systems.
Finally this study highlighted the need for further research in a number of key areas in order that muscle glycogen concentration in lambs to be fully understood. In particular, the role of muscle glycogen turnover in relation to muscle glycogen concentration was noted as an area for which further research is warranted.
39
Jacob, Robin Henry. "Optimising the concentration of glycogen in lamb meat." Jacob, Robin Henry (2003) Optimising the concentration of glycogen in lamb meat. PhD thesis, Murdoch University, 2003. http://researchrepository.murdoch.edu.au/110/.
Full textAbstract:
The lamb industry is actively seeking to improve the quality of lamb meat produced in Australia. Ultimate pH (pHu) is a key determinant of red meat eating quality although this measurement has not been adopted formally by the Australian lamb meat industry. Muscle glycogen concentration is a major determinant of pHu in red meat. This thesis investigates glycogen concentration in lamb muscle and the ultimate pH (pHu) of lamb meat under commercial industry conditions as well as exploring by experimentation, some of the factors that control muscle glycogen concentration in lamb muscle. The results of this work has contributed to an understanding of the significance of high pHu meat to the lamb industry and will assist with developing new management strategies for lambs that avoid low muscle glycogen concentration at the point of slaughter, thus high pHu in meat derived from lambs.
The first part of the study (Experiments 1 and 2) undertook to determine the ranges of muscle glycogen concentration and lamb meat pHu found under commercial conditions and to measure any changes in these parameters associated with consignment of lambs from farm to abattoir and lairage at abattoirs. This study utilised a new biopsy technique that allowed muscle collection from lambs on farm. Some 16 different consignments of lambs and 3 consignments of lactating ewes were intensively monitored on farm and at abattoirs over a range of lairage times. Sensory evaluation tests were done using meat from 6 of these consignments.
The results showed there to be considerable variation between lamb consignments with some consignments having a very high and other consignments having a very low incidence of meat with a high pHu. On balance 'on farm' factors were concluded to have a greater impact on muscle glycogen concentration at slaughter than 'post farm gate' factors. However, there was evidence that muscle glycogen concentrations decreased during the farm curfew and transport period for some consignments so both 'on farm' and 'post farm gate factors' can be important. Characteristically glycogen loss occurred during the farm curfew and transport period in consignments of Merino lambs that had high muscle glycogen concentrations prior to consignment. Holding lambs in lairage caused no negative effects on muscle glycogen concentration although there was some evidence that very short lairage periods may increase meat pHu without causing a change in muscle glycogen concentration. It was concluded from these experiments that the mean muscle glycogen concentration of a group of lambs needs to be greater than 1.5 g/100g on farm in order for the pHu of lamb meat to be less than 5.7.
Subsequent to this industry study, an experiment (Experiment 3) was done to gain an understanding of muscle glycogen concentration as being an integral part of whole body glucose metabolism. This experiment investigated the effects of exercise on a range of different muscles and tissues of lambs including liver, kidney, skin and gastrointestinal tract. Interactions between glycogen concentrations in the liver and muscle with time after exercise showed that glycogen repletion occurred in the liver before muscle tissue. This effect was a unique finding and could explain in part the slow rate of glycogen repletion in muscle tissue that is characteristic for ruminants. Another major finding was an accumulation of glycogen concentration in skin during the recovery period after exercise. It was postulated that this effect may be due to the supply of glucose to glycolytic tissues being continued even when demand for glucose in the skin was low and the capacity to store glycogen in muscle was very high.
Experiment 3 confirmed the existence of a relationship between metabolisable energy (ME) intake and glycogen repletion in muscle tissues and found a slightly different relationship between ME intake and glycogen repletion in the liver tissue of lambs. Muscle glycogen concentration did not change in fasted lambs and the rate of glycogen repletion in muscle after exercise was dependent on ME intake. Differences were observed between different muscles, particularly between M. longissimus thoracis et lumborum (LTL) and all other muscles, in relation to the change in glycogen concentration with time after exercise. Glycogen concentrations changed less rapidly in the LTL than other muscles. Glycogen concentration in the liver was associated negatively with time after exercise in fasted lambs and positively with time after exercise in fed lambs.
Several experiments (Experiments 4, 5 and 6) were conducted to determine the affects of different nutritional factors on muscle glycogen concentration in lambs, both on farm and after commercial slaughter. These studies showed that short term increases in ME intake will increase muscle glycogen concentration to a maximum level over a period of about 7 days (Experiment 4). Diet composition did not affect the change in muscle glycogen concentration associated with an increase in ME intake although results from this experiment (Experiment 5) were not entirely conclusive. There was evidence that the type of feeding and finishing system may influence the susceptibility of muscle glycogen concentration to change during consignment of lambs to slaughter. Results from these experiments demonstrated that a goal for muscle glycogen concentration in lambs on farm of 1.5g/100g is quite achievable with contemporaneous management systems.
Finally this study highlighted the need for further research in a number of key areas in order that muscle glycogen concentration in lambs to be fully understood. In particular, the role of muscle glycogen turnover in relation to muscle glycogen concentration was noted as an area for which further research is warranted.
40
Dillon, Vivian Maureen. "Sulphite tolerance of yeasts from comminuted lamb products." Thesis, University of Bath, 1988. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.383909.
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Van, der Westhuizen E. J. "The effect of slaughter age on the lamb characteristics of Merino, South African Mutton Merino and Dorper lambs." Thesis, Stellenbosch : University of Stellenbosch, 2010. http://hdl.handle.net/10019.1/4331.
Full textAbstract:
Thesis (MScAgric (Animal Sciences))--University of Stellenbosch, 2010.ENGLISH ABSTRACT: The aim of this study was to investigate the effect of feedlot production on the growth and carcass characteristics, as well as the distribution of the main tissues (muscle, fat and bone) and meat quality of Merino, South African Mutton Merino (SAMM) and Dorper lambs. The Merino and SAMM 2008 outperformed (P<0.05) the 2007 SAMM and both Dorper production groups in terms of average daily gain, while the Merino and both SAMM production groups achieved the best feed conversion ratio (P<0.05). The highest percentage A2 graded carcasses was achieved after 42 days under feedlot conditions by the Merino and both Dorper production groups, but it took only 21 days in the feedlot for the SAMM lambs to achieve the same result. Slaughter weight, carcass weight and dressing percentage all increased significantly with an increase in the number of days under feedlot conditions for all three breeds, while a decrease in the percentage head, trotters and red offal was also documented. The fatter retail cuts (thick rib, flank, prime rib and loin) increased (P<0.05) in percentage with an increase in the number of days under feedlot conditions. A significant decrease in the percentage leaner retail cuts (raised shoulder and hind-quarters) was found when the amount of days under feedlot conditions increased. The highest profit is obtained by the prime rib, loin and hind-quarters in a lamb carcass. For the Merino and Dorper lambs these three cuts, or a combination of the three showed the highest combined percentages after 42 and 63 days under feedlot conditions, respectively. The late maturing SAMM lambs achieved the highest percentages for these three cuts after 63 and 84 days under feedlot conditions in 2007 and 2008 respectively. Visceral and renal fat deposition increased throughout the production period for all breeds. The Dorper lambs attained the highest subcutaneous fat depth, and also produced the heaviest, but fattest carcasses. For A2-graded carcasses, Dorper lambs had the highest dressing percentage and lowest subcutaneous fat depth, followed by the SAMM and then Merino breed. A decrease in the percentage muscle and bone was found with an increase in the number of days under feedlot conditions, whilst an increase in the percentage fat was found under the same conditions. Meat quality was mostly affected by the 48h post mortem pH. This pH value is affected by the cooling rate of the carcasses, which in turn is affected by the level of carcass fatness. Carcass fatness increased with an increase in the number of days under feedlot conditions, resulting in a low 48h post mortem pH. A low 48h post mortem pH is accompanied by higher percentages of cooking and drip loss, as well as a high a*-colour reading for all three breeds.
AFRIKAANSE OPSOMMING: Die doel van hierdie studie was om die effek van voerkraalproduksie op die groeivermoë, karkaseienskappe, verspreiding van spier, been en vet, en vleiskwaliteit van Merino, Suid-Afrikaanse Vleismerino (SAVM) en Dorperlammers te bepaal. Die Merino en SAVM 2008 produksiegroepe het hoër (P<0.05) gemiddelde daaglikse toenames getoon as die SAVM 2007 en beide Dorper groepe, terwyl die Merino en beide SAVM produksiegroepe die beste voeromset verhoudings bereik het (P<0.05). Die hoogste persentasie A2 gegradeerde karkasse is na 42 dae in die voerkraal deur die Merino en beide Dorper produksiegroepe geproduseer, terwyl dit slegs 21 dae onder dieselfde toestande vir die SAVM groepe geneem het om dieselfde resultaat te lewer. Daar is ‘n betekenisvolle verhoging in slagmassa, karkasmassa en uitslagpersentasie vir al drie die rasse gevind met ‘n toename in die aantal dae in die voerkraal, terwyl ‘n afname in die persentasie kop, pote en haarslag gevind was. Die persentasie vetter groothandelsnitte (dikrib, dunrib, ribtjop en lendesnit) het toegeneem (P<0.05) met ‘n toename in die aantal dae in die voerkraal. ‘n Betekenisvolle afname in die persentasie van die maerder groothandelsnitte (blad en boude) is gevind met ‘n toename in die aantal produksie dae in die voerkraal. Die hoogste inkomste van ‘n lamkarkas is afkomstige van die ribtjop, lende snit en boude. ‘n Kombinasie van hierdie drie snitte was die hoogste vir die lammers van die Merino en beide Dorper groepe na 42 en 63 dae in die voerkraal onderskeidelik. Die laat volwasse SAVM lammers het die hoogste persentasie van hierdie drie snitte bereik na 63 en 84 dae in die voerkraal vir die SAVM 2007 en SAVM 2008 onderskeidelik. Die neerlegging van pensvet en niervet het voortdurend toegeneem deur die produksieperiode vir al drie rasse. Die Dorperlammers het die hoogste onderhuidse vetneerlegging getoon, maar het ook die swaarste en vetste karkasse geproduseer. Dorperlammers het die hoogste uitslagpersentasie en laagste onderhuidse vetneerlegging vir A2 gegradeerde karkasse gehad, gevolg deur die SAVM en Merino. ‘n Afname in die persentasie spier en been in karkasse is waargeneem namate die lammers langer in die voerkraal was, terwyl ‘n toename in die persentasie vet onder dieselfde omstandighede waargeneem is. Die 48h post mortem karkas pH affekteer die meeste vleiskwaliteit eienskappe. Hierdie pH waarde word weer deur die tempo van karkasafkoeling beϊnvloed, wat op sy beurt deur die vetheidsgraad van die karkas bepaal word. Die vetheid van karkasse het toegeneem met ‘n toename in die aantal dae in die voerkraal, wat ‘n lae pH waarde 48h post mortem tot gevolg gehad het. ‘n Lae 48h post mortem pH waarde het gelei tot hoër persentasies kook- en dripverliese en hoë a* kleurlesings vir al drie rasse.
42
Rainisch, Uri. "Detection of Ultrasonic Lamb Waves in Paper Using an Optical MEMS Microphone." Thesis, Georgia Institute of Technology, 2004. http://hdl.handle.net/1853/4779.
Full textAbstract:
Laser ultrasonics has been used to measure the bending stiffness of paper products by measuring the dispersion of ultrasonic plate waves. In laser ultrasonics, ultrasound can be generated by absorption of pulsed laser spot while detection can be carried out by Laser Doppler Interferometry. The research presented in this paper describes a new method to detect ultrasonic plate waves using a recently developed acoustic transducer, more specifically an optical Micro ElectroMechanical System (MEMS) microphone with broadband capability. The MEMS device operates as a non-contact proximity probe placed less than ¼ a millimeter away from the plate. The signals are detected with a capacitive micromachined ultrasonic transducer (cMUT) in which the back electrode of the capacitive transducer on a transparent substrate is shaped as an optical diffraction grating. The displacement of the transducer membrane is determined using an optical interferometer. By applying voltage to deflect the membrane electrostatically, the detection sensitivity is kept at an optimum level.
The main purpose of the research presented herein was to test this MEMSs ability to detect ultrasonic waves propagating through paper, to increase the signal-to-noise ratio (SNR), and to calibrate the device in order to quantify the limitations on sensitivity in the context of the detection of ultrasound in paper. Similar tests were conducted for comparison with a modified Mach-Zehnder Interferometer, a more traditional method used for laser ultrasonic detection, and its results are presented in this paper.
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Ismed, Friardi. "Phytochimie de lichens du genre Stereocaulon : étude particulière de S. Halei Lamb et S. montagneanum Lamb, deux lichens recoltés en Indonésie." Phd thesis, Université Rennes 1, 2012. http://tel.archives-ouvertes.fr/tel-00737382.
Full textAbstract:
Des études morphologiques, phylogénétiques et des analyses phytochimiques ont été menées sur neuf espèces de lichens fruticuleux du genre Stereocaulon à partir d'échantillons provenant de zones tropicales (Indonésie, Île de la Réunion) et de zones tempérées (France, Italie). Les divers résultats et la comparaison des observations ont permis de préciser certains éléments pour la classification et la diagnose très délicate de ces lichens et de sélectionner deux espèces pour une analyse plus approfondie de leurs métabolites secondaires. L'étude phytochimique a été conduite sur S. halei et S. montagneanum, qui ont été récolté dans l'île de Sumatra. Parmi la quinzaine de métabolites isolés, certains sont communs à ces deux espèces et correspondent à un depside abondant, l'atranorine et des dérivés mono-aromatiques associés. Des depsidones différencient les deux espèces comme l'acide lobarique et des dérivés dans S. halei, l'acide lobariolcarboxylique étant isolé pour la première fois et caractérisé sous forme de conformères. Dans S. montagneanum, ce sont l'acide stictique et des dérivés qui ont été identifiés. Ces profils métaboliques différents rejoignent les résultats de l'étude phylogénétique qui distingue respectivement S. halei et S. montagneanum dans les sous-genres Aciculisporae et Holostelidium. Malgré des activités inégales, aucun des 6 composés obtenus en quantité suffisante pour des test à visée photoprotective ne montre de résultat remarquable. Certains composés de type mycrosporine ont été caractérisés dans diverses parties du pseudopodétion et pourraient aussi présenter un intérêt pour la compréhension des répartitions métaboliques au sein des lichens tripartites.
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Tschirhart, Tara Elizabeth. "Histological, physical, and chemical factors of various lamb muscles." Texas A&M University, 2003. http://hdl.handle.net/1969.1/235.
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Muscles (n = 18) were dissected from each side of twenty lamb carcasses. Muscles from the right sides of the carcasses were used to determine weight, length, width, minimum and maximum thickness, objective color measurements, water-holding capacity (WHC), pH, total collagen content, sarcomere length, and fat and moisture content. Muscles from the left sides of the carcasses were aged for seven days and used to determine percent cook loss, and Warner-Bratzler shear force values. The M. teres major was lightest (P < 0.05) in weight and smallest in surface area, while the M. longissimus lumborum was heaviest (P < 0.05) in weight, and the M. serratus ventralis was largest in surface area. M. adductor and M. semimembranosus were found to be the darkest in color (P < 0.05), while the M. latissimus dorsi and M. tensor fasciae latae were the lightest (P < 0.05). M. triceps brachii had the highest WHC and the M. longissimus lumborum the lowest. The M. teres major and M. serratus ventralis had the highest (P < 0.05) pH values. The M. infraspinatus was found to have the highest collagen content (9.00 mg/g) and the M. psoas major revealed the longest sarcomere lengths (3.06 μm). M. serratus ventralis possessed the highest (P < 0.05) percent fat and the lowest moisture content. M. serratus ventralis had the lowest cook loss (17.1%) and M. supraspinatus had the highest (25.6%). Of the muscles sampled, the M. serratus ventralis was found to have the lowest shear force value (21.8 newtons) and the M. semimembranosus had the highest (42.6 newtons).
Based on the findings of these data, it is likely to conclude that certain muscles may be suitable for individual muscle applications while others may not be suitable or may pose certain palatability problems.
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Rodríguez, Gillian Anne. "The potential manifestation of place as a brand component of regional meat : the cases of Cumbrian salt marsh lamb and Herdwick lamb." Thesis, University of Newcastle upon Tyne, 2015. http://hdl.handle.net/10443/2924.
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Purpose – the purpose of this research is to explore respondents’ knowledge of regional foods including the pre-product stage i.e. in the landscape. Herdwick lamb and Cumbrian salt marsh lamb are both highly visible in the landscape and form part of the ‘lifescape’ of local residents. Design/method/approach – taking a phenomenological stance the research examines the experiential claims of respondents; means-end chain analysis was selected to gather customer values relating to this broader product concept. Ladder maps were drawn up for each of two sets of twenty respondents residing in the production region of either lamb. Hierarchical value maps are produced to reveal salient connections. Findings – show that respondents hold a very wide range of perceptions, experiences and associations with the ‘pre-products’, which influences their judgement about the freshness, flavour, quality of the meat. The ability to fulfil other functions by buying regional meat became apparent, in particular the need to make a contribution to the local economy, to support the ecology, and to know the place through community interaction. Respondents were found to interact with the landscape on two levels, perception and inner reflection. Practical implications – effective regional food brands may be characterised by branding actions which do not have the food product details at their core. The development of relationships, events and brand communities in a shared place may sustain producers who have their volume output limited by what the land will bear. Originality and value – the limitations of some marketing structures are considered for adaptation including: Boatwright et al.’s (2009) value opportunity analysis and Keller’s (2008) consumer based brand equity model. An opportunity for creation of a new category of attribute, relating to experience of ‘pre-products’ in the landscape is discussed.
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Kotte, Timo Oliver. "Application of Image Processing Techniques for Lamb Wave Characterization." Thesis, Georgia Institute of Technology, 2004. http://hdl.handle.net/1853/4787.
Full textAbstract:
Characterization of dispersion curves in plate-like structures is possible with guided Lamb waves. In this research, experimental development of dispersion curves relies on the spectrogram, which suffers from the Heisenberg Uncertainty Principle. Reassignment is capable of localizing ill--defined dispersion curves. Unfortunately, reassignment also introduces spurious components, which reduce reassignment performance. This research develops an algorithm that provides both localization of dispersion curves and elimination of spurious components. To achieve this, an alternative formulation
of reassignment called differential reassignment is modified and superimposed with nonlinear anisotropic diffusion. This study first examines reassignment and diffusion components individually. Three different versions of differential reassignment are considered, two of which are modifications explicitly derived in
this research. The combined algorithm is then applied to reassign experimentally measured spectrograms, leading to a significant increase in clarity and notch detection performance.
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Gandhi, Navneet. "Determination of dispersion curves for acoustoelastic lamb wave propagation." Thesis, Georgia Institute of Technology, 2010. http://hdl.handle.net/1853/37158.
Full textAbstract:
The effect of stress on Lamb wave propagation is relevant to both nondestructive evaluation and structural health monitoring because of changes in received signals due to both the associated strain and the acoustoelastic effect. A homogeneous plate that is initially isotropic becomes anisotropic under biaxial stress, and dispersion of propagating waves becomes directionally dependent. The problem is similar to Lamb wave propagation in an anisotropic plate, except the fourth order tensor in the resulting wave equation does not have the same symmetry as that for the unstressed anisotropic plate, and the constitutive equation relating incremental stress to incremental strain is more complicated. Here we review the theory of acoustoelastic and develop theory for acoustoelastic Lamb wave propagation and show how dispersion curves shift anisotropically for an aluminum plate under biaxial tension. We also develop an approximate method using the effective elastic constants (EECs) and show that existing commercial tools to generate dispersion curves can be used under restricted conditions to describe wave propagation in biaxially stressed plates. Predictions of changes in phase velocity as a function of propagation direction using theory and the EEC method are compared to experimental results for a single wave mode.
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Engholm, Marcus. "Ultrasonic Arrays for Sensing and Beamforming of Lamb Waves." Doctoral thesis, Uppsala universitet, Signaler och System, 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-122189.
Full textAbstract:
Non-destructive testing (NDT) techniques are critical to ensure integrity and safety of engineered structures. Structural health monitoring (SHM) is considered as the next step in the field enabling continuous monitoring of structures. The first part of the thesis concerns NDT and SHM using guided waves in plates, or Lamb waves, to perform imaging of plate structures. The imaging is performed using a fixed active array setup covering a larger area of a plate. Current methods are based on conventional beamforming techniques that do not efficiently exploit the available data from the small arrays used for the purpose. In this thesis an adaptive signal processing approach based on the minimum variance distortionless response (MVDR) method is proposed to mitigate issues related to guided waves, such as dispersion and the presence of multiple propagating modes. Other benefits of the method include a significant increase in resolution. Simulation and experimental results show that the method outperforms current standard processing techniques. The second part of the thesis addresses transducer design issues for resonant ultrasound inspections. Resonant ultrasound methods utilize the shape and frequency of the object's natural modes of vibration to detect anomalies. The method considered in the thesis uses transducers that are acoustically coupled to the inspected structures. Changes in the transducer's electrical impedance are used to detect defects. The sensitivity that can be expected from such a setup is shown to highly depend on the transducer resonance frequency, as well as the working frequency of the instrument. Through simulations and a theoretical argumentation, optimal conditions to achieve high sensitivity are given.
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Dalton, Roger Patrick. "Propagation of LAMB waves in metallic aircraft fuselage structure." Thesis, Imperial College London, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.392345.
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Diligent, Olivier. "Interaction between fundamental lamb waves and defects in plates." Thesis, Imperial College London, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.407494.
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