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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
121

Résolution de problème individuelle et coopérative chez le diamant mandarin (Taeniopygia guttata)

Bouchoucha, Rim 12 1900 (has links)
La résolution de problème est souvent utilisée comme outil de mesure des capacités cognitives individuelles chez les animaux non-humains, puisqu’elle permet d’étudier leurs capacités d’apprentissage opérant et d’innovation. Les capacités cognitives diffèrent selon les espèces et les individus, et leur permettent de maximiser leur aptitude. Par exemple, chez les oiseaux et les mammifères, les espèces avec de plus gros cerveaux relatifs possèderaient de meilleures capacités d’apprentissage sociale et d’innovation, qui leur permettent de mieux s’adapter à un environnement nouveau. Malgré l’utilisation répandue des diamants mandarins dans la recherche en écologie comportementale, l’impact du sexe sur la performance de résolution de problème et la répétabilité des performances ont souvent été négligés, et aucune étude, à notre connaissance, ne s’est intéressée à leur performance en contexte de résolution de problème coopérative. Dans le cadre de notre étude, nous avons décidé d’aborder ces différents aspects pour améliorer notre compréhension des capacités cognitives et de la coopération chez cette espèce modèle. Nous avons confronté des diamants mâles et femelles à trois tests de résolution de problème individuelle (test de la ficelle, test de la barre et test du couvercle) et un test de résolution de problème coopérative. Pour ce dernier, nous avons séparé les individus en deux groupes : couples sociaux et couples expérimentaux, afin de manipuler le lien social entre individus. Les couples sociaux étaient composés d’un mâle et d’une femelle ayant cohabité pendant 7 jours, alors que les couples expérimentaux étaient composés d’un mâle et d’une femelle ne s’étant jamais rencontrés auparavant. Bien que nous nous attendions à ce que le sexe n’ait pas d’impact sur la performance de résolution, nos résultats ont révélé que, en moyenne, les mâles étaient plus rapides pour résoudre un test de résolution de problème individuelle. Ces résultats étaient principalement attribuables à leur performance sur le deuxième test de résolution de problème individuelle (test de la barre). Nous pensons que cette différence pourrait être due à un niveau de persistance plus élevé chez les mâles et/ou à l’impact de la sélection sexuelle sur les performances cognitives, et que ces aspects devraient être davantage explorés dans de futures études. Ensuite, en accord avec nos attentes, nos résultats ont confirmé l’hypothèse de la répétabilité contextuelle, selon laquelle les performances de résolution sont constantes entre différentes tâches impliquant le même processus cognitif. Enfin, nous nous attendions à ce que les couples sociaux soient plus performants que les couples expérimentaux sur le test de résolution de problème coopérative, puisque nous les pensions davantage capables de synchronisation et de coordination comportementale. Or, nous avons trouvé des résultats suggérant le contraire, et nous avons constaté que la performance du couple au test de résolution de problème coopérative, était principalement expliquée par les performances de résolution individuelle de chaque partenaire. Des questions subsistent quant aux raisons pour lesquelles les couples expérimentaux ont mieux performé que les couples sociaux. Est-ce qu’une différence de motivation pourrait être à l’origine de ces résultats ? De futures études seront nécessaires pour nous éclairer. Malgré les questions en suspens, nos résultats contribuent à enrichir nos connaissances sur les capacités cognitives individuelles, la résolution de problème ainsi que la coopération. / Problem solving is often used as a tool for measuring individual cognitive abilities in non-human animals, since it enables us to study their operant learning and innovation capacities. Cognitive capacities differ between species and individuals, enabling them to maximize their abilities. For example, in birds and mammals, species with larger relative brains are said to have better social learning and innovation capacities, enabling them to adapt better to new environments. Despite the widespread use of zebra finches in behavioral ecology research, the impact of sex on problem-solving performance and the repeatability of performance have often been overlooked and, to our knowledge, no studies have investigated their performance in cooperative problem-solving contexts. In our study, we decided to address these different aspects to improve our understanding of cognitive abilities and cooperation in this model species. We tested male and female zebra finches in three individual problem-solving tests (string test, bar test and lid test) and one cooperative problem-solving test. For the latter, we separated the individuals into two groups: social pairs and experimental pairs, to manipulate the social bond between individuals. Social pairs were made up of a male and a female who had cohabited for 7 days, while experimental pairs were made up of a male and a female who had never met before. While we expected sex to have no impact on solving performance, our results revealed that, on average, males were faster at solving individual problem-solving tests. These results were mainly attributable to their performance on the second individual problem-solving test (bar test). We believe that this difference could be attributable to a higher level of persistence in males and/or the impact of sexual selection on cognitive performance, and that these aspects should be explored in future studies. Secondly, in line with our expectations, our results confirmed the contextual repeatability hypothesis, according to which solving performance is consistent across trials requiring the same cognitive process. Finally, we expected social pairs to perform better than experimental pairs on the cooperative problem-solving test, since we expected them to be more capable of synchronisation and behavioral coordination. . However, we found results suggesting the opposite, and the performance of the pairs on the cooperative problem-solving task was mainly explained by the ability of each partner to solve a problem. Questions remain as to why the experimental pairs performed better than the social pairs. Could a difference in motivation be behind these results? Future studies are needed to shed light on this. Despite the outstanding questions, we believe that our results contribute to our knowledge of individual cognitive abilities, problem solving and cooperation.
122

<b>Optimizing Genetic Selection for Mature Cow Size in North American and Australian Angus Cattle</b>

Ayooluwa Omobolaji Ojo (20369949) 16 December 2024 (has links)
<p dir="ltr"> Improving feed efficiency in beef cattle is essential to meet rising global beef demand while reducing costs and environmental impacts. Genetic selection plays a significant role in identifying and breeding more feed-efficient animals, with multi-population data integration enhancing prediction accuracy. To optimize animals for selection or breeding programs related to efficiency, it is crucial to understand the traits associated with mature cow size and the genetic relationships between them. Mature cow size, defined by mature cow weight (MWT), height (MHT), and body condition score (BCS), is pivotal to cow-calf profitability, maintenance efficiency, and reproductive performance.<br><br> The objectives of the first study were to: 1) estimate variance components and genetic parameters for MWT, MHT, and BCS in the United States (US) and Australia (AUS); 2) estimate genetic correlations between mature cow size traits and early growth and carcass traits; and 3) estimate the genetic correlations among these traits across the two countries. The datasets provided by the American Angus Association and Angus Australia included 434,746 and 206,003 records for MWT, 213,875 and 15,379 records for MHT, and 382,156 and 36,184 records for BCS, respectively. Single-trait repeatability models were used to estimate heritabilities and variance components. Multiple-trait models were used to estimate phenotypic and genetic correlations between traits and across countries. Heritability estimates for MWT (US: 0.45; AUS: 0.40), MHT (US: 0.57; AUS: 0.63), and BCS (US: 0.18; AUS: 0.18) highlighted moderate-to-high genetic control. Genetic correlations within the US and Australian datasets between MWT and MHT, and MWT and BCS were > 0.50, and < 0.20 between MHT and BCS. Genetic correlations between MWT, MHT and early growth traits were generally positive and moderate-to-high, ranging from 0.51(0.01) to 0.92(0.003) in the US and 0.41(0.03) to 0.79(0.05) in Australia. Genetic correlations between the traits in the two countries were high for MWT = 0.91 (0.02) and MHT = 0.98 (0.02); and moderate for BCS = 0.65 (0.08). The results suggested that optimizing selection for mature cow traits is feasible, and that a joint evaluation between the US and Australia could be beneficial. </p><p dir="ltr"><br></p><p dir="ltr"> The objective of the second study was to investigate the impact of different modeling approaches on the estimation of breeding values for MWT, with a focus on how BCS was treated across models. The dataset provided by American Angus Association comprised 382,156 MWT and BCS records from 209,491 cows. Four modeling approaches were evaluated: Model 1 did not consider BCS; Model 2 treated BCS as a categorical fixed effect; Model 3 used pre-adjusted records standardized for BCS and age; and Model 4 used a recursive model to assess MWT as a genetically independent trait from BCS. Spearman correlations between models ranged from 0.78 to 0.95, with model choice influencing sire rankings by 5–22% and top 10% concordance differing by up to 40%. Model selection can significantly affect rankings, highlighting the importance of carefully selecting the model that aligns best with the breeding goals. The recursive approach appears to effectively derive MWT that is genetically independent of BCS. </p><p dir="ltr"> This thesis analyzes genetic relationships among mature cow size traits; mature cow weight, height, and body condition score, providing insights for selection programs aimed at optimizing cow’s efficiency. Through variance analysis and genetic correlation studies across North American and Australian Angus populations, it highlights the potential of joint evaluations across countries. It also assesses how different modeling approaches for estimating breeding values for mature cow weight can affects sire rankings and selection decisions, underscoring the importance of model alignment with breeding objectives. Ultimately, this work contributes to the goal of a more sustainable beef industry, where mature cow size is optimized.</p>
123

Personality and pace-of-life syndrome in fishes: New perspectives

Polverino, Giovanni 24 November 2017 (has links)
Individuelle Verhaltensunterschiede (sog. „Animal personality“) werden oft als konsistent über die Zeit und situationsunabhängig angenommen. Vielfach werden solche Persönlichkeitsunterschiede zwischen Tieren einer Art durch individuelle Unterschiede im Energiehaushalt sowie Lebenszyklusvariablen (sog. ‚state variables‘, dt. Zustandsgrößen) erklärt. Dies ist in der „pace-of-life“ Hypothese zusammengefasst. In neueren Arbeiten wurde jedoch die Konsistenz von Persönlichkeitsmerkmalen über den Lebensverlauf und deren strikte Abhängigkeit von Zustandsgrößen in Frage gestellt. Die vorliegende Dissertation soll neue Einblicke in die Mechanismen, die zur Entstehung von Persönlichkeitsunterschieden im Verlauf des Lebens von Fischen, deren Situationsabhängigkeit sowie ihre Verbindung zu individuellen Unterschieden in Zustandsgrößen liefern. In einer Abfolge von fünf unabhängigen Studien untersuchte ich die genannten Annahmen und fand, dass (1) Persönlichkeitsunterschiede sich im Laufe des Lebens von Tieren vergrößern; (2) Persönlichkeitsabschätzungen bei jungen Tieren oft stärker vom experimentellen Aufbau beeinflusst werden als bei Erwachsenen; (3) der Energiehaushalt und Lebenszyklusvariablen Persönlichkeitsunterschiede sowohl unter Laborbedingungen als auch im Freiland nicht hinreichend erklären können; (4) Beziehungen zwischen Persönlichkeitsunterschieden und Unterschieden im Energiehaushalt und in Lebenszyklusvariablen fanden sich nur bei Fischen einer Population mit langsamer Lebenszyklusstrategie nicht jedoch in einer Population mit schnellem Lebenszyklus. Die vorliegende Arbeit suggeriert daher, dass sich erst im Verlauf des Lebens eines Tieres Persönlichkeitsunterschiede unvermeidbar entwickeln. Dies stellt Persönlichkeitsmessungen bei juvenilen Tieren grundsätzlich in Frage. Weiterhin scheinen Persönlichkeitsunterschiede und Zustandsgrößen unter bestimmten Umweltbedingungen und evolutiven Szenarien voneinander unabhängig zu sein. / Among-individual differences in behavior (i.e., animal personality) are assumed to be consistent over time and contexts. In theory, they are often explained by individual variations in energy costs of self-maintenance as well as life history among animals (i.e., state variables), commonly expressed as the pace-of-life syndrome hypothesis. Yet, recent theories have disputed the consistency of personality types over lifetime and their rigid state-dependency. This thesis aims to offer novel insights on the mechanisms behind the emergence and development of personality over lifetime of fishes, its context dependency, and its link to individual variation in state variables. In a sequence of five independent yet interconnected studies, I tested the assumptions above and observed that (1) personality differences increased during lifetime as a function of consistent declines in the behavioral plasticity with increasing age of animals; (2) personality estimates in young animals were weaker and thus more vulnerable to experimental biases compared to adults; (3) personality variation did not depend upon individual differences in energy costs of self-maintenance and life-history traits among individuals, under both laboratory and natural settings; and (4) the relationship between behavioral, metabolic, and life-history traits was manifested only in fish populations with slow rather than fast life-history strategies. This thesis suggests that personality variation in animals might be the inevitable outcome of development, raising questions about the reliability of personality estimates in juvenile individuals. Furthermore, individual variation in personality and “states” may act independently (i.e., phenotypes are uncorrelated) under environmental conditions and evolutionary contexts that mask or select against their trade-offs.
124

Problematika šablonového tisku pájecí pasty pro součástky s malou roztečí vývodů / Problems in Solder Paste Stencil Printing for Fine Pitch Components

Šimeček, Ondřej January 2011 (has links)
Despote the indisputable advantages of fine-pitch components, is need to calculate with a few trouble during production, especially increased requirements for accuracy of mounting and solder printing. In this work I’m concerned with problems of solder printing for these components and evaluation using SPC. For the evaluation I used 3D paste inspection based on laser scanning of the surface. The output of this work is to describe the principles of solder printing and elaborating of GR&R, SPC analysis and histograms of solder printing for some outputs. I focused in my master thesis on motive design change of problematic components and economic evaluation of the adjustments.
125

Extension, Evaluation, and Validation of Load Based Testing for Residential and Commercial HVAC Equipment

Parveen Dhillon (14203079) 02 December 2022 (has links)
<p>With rising temperatures, urbanization, population growth, improving economic wellbeing, decarbonization and electrification efforts, the demand for space cooling and heating equipment is continuously increasing around the world. To counteract the effect of rising demand for air conditioners and heat pumps on total energy consumption, peak electricity demand, and emissions, it is crucial to promote the development and market penetration of energy-efficient systems. Establishing minimum energy performance standards (MEPS), energy labeling and utility programs are some of the effective and tested methods for achieving this goal. The technical basis for these energy efficiency standards is a testing and rating procedure for estimating equipment seasonal performance from laboratory tests. Although the current rating procedures provide standardized metrics to compare different equipment performances, they fail to appropriately characterize the field representative performance of systems by not considering the effects of: 1) test unit embedded controls, thermostat, and realistic interactions with the building load and dynamics; 2) different climate zones and building types; and 3) and other integrated accessories for improving energy efficiency such as economizer for rooftop units (RTUs). Therefore, current approaches for performance ratings neither incentives the development and implementation of improved system and control designs nor consumers with a metric that represents the advanced systems' actual energy savings. To address this, a load-based testing methodology that enables dynamic performance evaluation of equipment with its integrated controls, thermostat, and other accessories was recently proposed. The test methodology is based on the concept of emulating the response of a representative building conditioned by the test unit in a test lab using a virtual building model. </p> <p>In this work, the proposed load-based testing methodology was further extended, evaluated, and validated for residential heat pumps to integrate it into next-generation energy efficiency testing and rating procedures and to serve as a tool for engineers to develop and validate improved control algorithms in a laboratory setting. Further, a load-based testing method for evaluating the dynamic performance of RTUs with integrated economizers was also developed and demonstrated.</p> <p>A load-based testing approach previously developed for residential cooling equipment is extended for heat pump heating-mode and demonstrated for a variable-speed system. The heat pump's typical dynamic behaviors are captured along with controller imperfections that aren't reflected in current testing approaches. Further, a comprehensive comparison was performed between the proposed load-based testing approach to the current steady-state testing approach in the U.S., AHRI 210/240, based on performance evaluation of three residential variable-speed heat pumps to understand the differences and their significance for the next-generation rating procedure. For cooling mode, steady-state testing estimates higher seasonal performance, but for heating mode, the steady-state testing approach estimates higher seasonal performance for warmer climates and is comparable for colder climates. The load-based testing methodology was validated by comparing the laboratory performance of a heat pump to that of a residential building in a controlled environment. The virtual building modeling approach for building loads and thermal dynamics effectively captured these characteristics of the house. The heat pump's cycling rate response with run-time fraction, which represents the unit's overall dynamic response, matched well between lab load-based tests and house tests. The test unit's COP difference for cooling and heating tests was within 3% between the two facilities, except for 9% in 95°F and 6% in 104°F cooling dry-coil test intervals. To evaluate the applicability of the developed load-based testing methodology as next-generation rating standards, its repeatability and reproducibility were assessed based on multiple heat pump round-robin tests conducted in two labs. Overall, reasonable to good repeatability was observed in load-based test results in both labs, however, poor reproducibility was observed except for one heat pump heating mode results. A root cause analysis of the observed differences along with recommendations for a next-generation rating approach are presented. This work aided in the development of a CSA (Canadian Standards Association) standard EXP07:19 and its subsequent revision for equipment rating based on load-based testing.</p> <p>The application of the load-based testing methodology as a tool for the development and evaluation of a residential heat pump controller design was demonstrated. Further, a load-based testing methodology was developed and demonstrated for the dynamic performance evaluation of RTUs with integrated economizers in a test laboratory setting. Recommendations for future work to further develop and improve the repeatability, reproducibility, and representativeness of the load-based testing and rating approach for residential and commercial air conditioners and heat pumps are summarized at the end of the dissertation. </p>
126

Využití přesného kapacitního mostu pro měření indukčnosti / Using of accurate capacitance bridge for inductance measurements

Uher, Miroslav January 2008 (has links)
This master’s thesis is dealing with possibilities of measurement of inductance by using of accurate capacitance bridge AH 2500E. In metrology there are no appropriate devices available for accurate measurement of inductance. It can be realized by four methods. The newest one is based on T elements, it is not used for this purpose yet and it is practically investigated in CMI Brno. For its introduction to practice it is neccessary to complete computer simulations and analysis of influences affecting measurement. It is also inevitable to examine repeatability of measurement, define methodology of measurement and potential corrections of measured values.

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