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Comparison of Compact Very High Frequency (VHF) Antennas for Small Airborne Ground Penetrating RadarLivingston, Tayler Austen 25 July 2023 (has links) (PDF)
UHF bands because more penetration can be achieved at low frequencies. Consequently, large antennas are required, which limits their use for small airborne applications. This thesis explores various GPR antenna designs for a bi-static system that are at least operational from 225 MHz to 255 MHz and suitable for small airborne applications. The 3D electromagnetic simulation software Ansys high-frequency structure simulator (HFSS) was used to simulate various sizes of strip dipole, triangular bowtie, half elliptical bowtie, and elliptical bowtie antennas. Several physical models were constructed to validate the return loss simulation results. Additionally, simulation data is included for a wire dipole and a helical antenna. The helical antenna proved to be too large for small airborne application, so focus was placed on the dipole and bowtie designs. The performance of the dipole and bowtie antenna models are compared by size, weight, return loss (ð‘†11), peak gain, and the transmit-to-receive isolation. Out of the fourteen simulated models, twelve meet the bandwidth requirement with an average weight of 0.23 lbs. It is found that the strip dipole exhibited wider bandwidth characteristics than the triangular, elliptical, and half elliptical bowtie models, while maintaining similar weight and size. The smallest strip dipole model is 50 mm x 528 mm x 1 mm, weighs 0.17 lbs, and is operational from 225 MHz to 283 MHz. Two strip dipole test antennas were fabricated and tested. Test results confirm the simulation predictions.
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First Order Self-Oscillating Class-D Circuit with Triangular Wave InjectionCarroll, Matthew J 01 June 2021 (has links) (PDF)
An investigation into performance improvements to the modulator stage of a class-D amplifier is conducted in this thesis. Two of the standard topologies, namely class-D open-loop pulse-width modulation (PWM), and the improved self-oscillating feedback system are benchmarked against a topology which includes both a hysteretic comparator in a feedback loop and triangle wave injection. Circuit performance is analyzed by comparing how the triangle injection circuit handles known issues with open-loop and self-oscillating circuits. Using this analysis, it is shown that the triangle injection topology offers an improved power supply rejection ratio relative to open-loop PWM and reduces distortion generated by frequency modulation characteristic of the self-oscillating topology.
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An ESL Learning Center: A Critical Case StudyChen, Ku-Yun 26 July 2013 (has links)
No description available.
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The Performance of Tuned Liquid Dampers with Different Tank GeometriesDeng, Xiaocong 04 1900 (has links)
<p> Tuned Liquid Dampers (TLDs) are increasingly being used to suppress the dynamic vibration of tall buildings. An equivalent mechanical model is essential for rapid analysis and design of a TLD. The most common TLD tank geometries are circular, annular and rectangular. Rectangular tanks are utilized for 1-D and 2-D TLDs, whereas circular and annular are usually applied to axisymmetric structures. The amount of fluid that participates in the sloshing motion is directly influenced by the tank geometry. Although not commonly used, a TLD having a curved-bottom tank is expected to perform more effectively due to its relatively large value of effective mass. The main objective of this study is to develop mechanical models for seven TLDs with different tank geometries including the curved-bottom case, and to theoretically investigate the performance of rectangular, vertical-cylindrical and horizontal-cylindrical TLDs.</p> <p> Potential flow theory, linear long wave theory, Lagrange's equations and virtual work method are employed to develop the equivalent mechanical model parameters of TLDs with rectangular, vertical-cylindrical, horizontal-cylindrical, hyperboloid, triangular, sloped-bottom, and parabolic tank geometries. A rectangular, vertical-cylindrical and horizontal-cylindrical TLD are selected for further study using a single-degree-of-freedom
(SDOF) model and a two degree of freedom structure-TLD system model applying the derived equivalent mechanical parameters.</p> <p> The dynamic characteristics of the TLDs as a SDOF system are investigated. The mechanical model is verified by comparing calculated values with experimental results for a rectangular TLD. The free surface motion, sloshing force and energy dissipation are found to be dependent upon the excitation amplitude. Analytical results also indicate that the horizontal-cylindrical TLD possesses the greatest normalized sloshing force and energy dissipation among the TLDs considered.</p> <p> The performances of various TLDs installed in a structure are studied in terms of effective damping, efficiency and robustness. Tuning ratio, structural response amplitude, mass ratio and liquid depth are adjusted to investigate their affect on the performance of the studied TLDs. Performance charts are developed and subsequently used to present the results. It is found that small liquid depth ratio and large mass ratio can lead to a robust structure-TLD system with small relative motion ratio between the structure and the vibration absorber. Comparisons of performance between the three TLDs are made and it can be concluded that the horizontal-cylindrical TLD is the most robust and effective device with the smallest relative motion ratio.</p> / Thesis / Master of Applied Science (MASc)
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Image Approximation using TriangulationTrisiripisal, Phichet 11 July 2003 (has links)
An image is a set of quantized intensity values that are sampled at a finite set of sample points on a two-dimensional plane. Images are crucial to many application areas, such as computer graphics and pattern recognition, because they discretely represent the information that the human eyes interpret. This thesis considers the use of triangular meshes for approximating intensity images. With the help of the wavelet-based analysis, triangular meshes can be efficiently constructed to approximate the image data. In this thesis, this study will focus on local image enhancement and mesh simplification operations, which try to minimize the total error of the reconstructed image as well as the number of triangles used to represent the image. The study will also present an optimal procedure for selecting triangle types used to represent the intensity image. Besides its applications to image and video compression, this triangular representation is potentially very useful for data storage and retrieval, and for processing such as image segmentation and object recognition. / Master of Science
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O papel das relações interpessoais na condução do ProSavana-JBM (Japão-Brasil-Moçambique): um estudo de caso: programa de Cooperação Triangular para o Desenvolvimento Agrícola da Savana Tropical de MoçambiqueFerreira, Melina de Souza-Bandeira 31 August 2012 (has links)
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Previous issue date: 2012-08-31 / This case study intends to report how interpersonal relationships might have played an important role on making ProSAVANA-JBM work. (Triangular Cooperation Program for Agricultural Development of the African Tropical Savannah in Mozambique-Japan-Brazil-Mozambique). The intermediary objectives contribute to for one to look into which other factors might have been determinant for realization of ProSAVANA. This program not only represents an international partnership between organizations of three countries: Brazil, Japan and Mozambique, but also has impacts of a social, economic and environmental nature. The data analysis shows that interpersonal relationships outstands among the other determining factors on the Programa realization, and corroborates for the design of an interpersonal relationship network’s model related to ProSAVANA. This study’s limitation refere to the difficulty on replicating or generalizing this study on a scientific basis, considering the fact that it wouldn’t be possible to imply on evaluations on a certain behavior exclusively based on a single case study. Finally, the purpose of this study is to offer theoretical and empirical tools that enable an in-depth assessment on the role played by interpersonal relationships, and also to contribute to bridging the gaps in the field of business and public administration. / O objetivo deste estudo de caso foi o de identificar o papel das relações interpessoais na condução do ProSAVANA-JBM (JAPÃO-BRASIL-MOÇAMBIQUE), Programa de Cooperação Triangular para o Desenvolvimento Agrícola da Savana Tropical de Moçambique. Os objetivos intermediários permitem também investigar quais outros fatores podem ter sido determinantes na condução do ProSAVANA. Este programa além de representar uma parceria internacional entre organizações de três países Brasil, Japão e Moçambique, possui impactos de ordem social, econômica e ambiental. A análise dos dados demonstra que as relações interpessoais exerceram a maior centralidade entre os demais fatores determinantes à condução do Programa, e também corrobora para o desenho de um modelo de rede de relações interpessoais relacionada ao ProSAVANA. As limitações do estudo referem-se à dificuldade deste estudo ser replicado ou generalizado cientificamente, considerando que não seria possível emitir avaliações sobre determinado comportamento, a partir de um estudo de caso único. Finalmente, o propósito deste estudo é oferecer instrumentos teóricos e empíricos que permitam aprofundar a reflexão sobre o papel das relações interpessoais, além de contribuir para as lacunas existentes no campo da gestão empresarial e pública.
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Quelques propositions pour la comparaison de partitions non strictes / Some proposals for comparison of soft partitionsQuéré, Romain 06 December 2012 (has links)
Cette thèse est consacrée au problème de la comparaison de deux partitions non strictes (floues/probabilistes, possibilistes) d’un même ensemble d’individus en plusieurs clusters. Sa résolution repose sur la définition formelle de mesures de concordance reprenant les principes des mesures historiques développées pour la comparaison de partitions strictes et trouve son application dans des domaines variés tels que la biologie, le traitement d’images, la classification automatique. Selon qu’elles s’attachent à observer les relations entre les individus décrites par chacune des partitions ou à quantifier les similitudes entre les clusters qui composent ces partitions, nous distinguons deux grandes familles de mesures pour lesquelles la notion même d’accord entre partitions diffère, et proposons d’en caractériser les représentants selon un même ensemble de propriétés formelles et informelles. De ce point de vue, les mesures sont aussi qualifiées selon la nature des partitions comparées. Une étude des multiples constructions sur lesquelles reposent les mesures de la littérature vient compléter notre taxonomie. Nous proposons trois nouvelles mesures de comparaison non strictes tirant profit de l’état de l’art. La première est une extension d’une approche stricte tandis que les deux autres reposent sur des approches dite natives, l’une orientée individus, l’autre orientée clusters, spécifiquement conçues pour la comparaison de partitions non strictes. Nos propositions sont comparées à celles de la littérature selon un plan d’expérience choisi pour couvrir les divers aspects de la problématique. Les résultats présentés montrent l’intérêt des propositions pour le thème de recherche qu’est la comparaison de partitions. Enfin, nous ouvrons de nouvelles perspectives en proposant les prémisses d’un cadre qui unifie les principales mesures non strictes orientées individus. / This thesis is dedicated to the problem of comparing two soft (fuzzy/ probabilistic, possibilistic) partitions of a same set of individuals into several clusters. Its solution stands on the formal definition of concordance measures based on the principles of historical measures developped for comparing strict partitions and can be used invarious fields such as biology, image processing and clustering. Depending on whether they focus on the observation of the relations between the individuals described by each partition or on the quantization of the similarities between the clusters composing those partitions, we distinguish two main families for which the very notion of concordance between partitions differs, and we propose to characterize their representatives according to a same set of formal and informal properties. From that point of view, the measures are also qualified according to the nature of the compared partitions. A study of the multiple constructions on which the measures of the literature lie completes our taxonomy. We propose three new soft comparison measures taking benefits of the state of art. The first one is an extension of a strict approach, while the two others lie on native approaches, one individual-wise oriented, the other cluster-wise, both specifically defined to compare soft partitions. Our propositions are compared to the existing measures of the literature according to a set of experimentations chosen to cover the various issues of the problem. The given results clearly show how relevant our measures are. Finally we open new perspectives by proposing the premises of a new framework unifying most of the individual-wise oriented measures.
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Schule als "triadischer Raum"Schantl, Helmut 17 November 2011 (has links)
Ausgehend von der These, dass das Verhalten „schwieriger“ Kinder eine Folge kulturell-gesellschaftlicher Entwicklungen ist, die sich nachteilig auf den innerpsychischen Prozess der Triangulierung auswirken und auf die eine von zweckrationalen Organisationsstrukturen, von institutionsspezifischen Kommunikations- und Handlungsformen und von einem veränderten professionellen Selbstverständnis einzelner Lehrer dominierte Schule bislang keine befriedigenden Antworten gegeben hat, wird nach dem Potenzial der Psychoanalyse hinsichtlich der Möglichkeit gefragt, Pädagogen und Pädagoginnen bei der Konstituierung von Schule als ‚triadischer Raum’ im Sinne eines dyadisch geprägten und triadisch strukturierten, die kindliche Entwicklung fördernden psychosozialen Erfahrungsraums zu unterstützen. Am psychoanalytischen Theorem der Triangularität orientiert wendet sich die Erörterung zunächst drei von der Psychoanalyse beeinflussten sozialisationstheoretischen Konzepten unterschiedlicher Provenienz zu. Dieses methodische Vorgehen erweist sich jedoch im Kontext der zentralen Zielsetzung, ein umfassendes pädagogisches Konzept zur Stärkung kindlicher triangulärer psychischer Strukturen zu skizzieren, nur bedingt als hilfreich. Die anschließende Diskussion der Problem- und Fragestellung auf der Folie einer ‚kulturtheoretisch orientierten’ Psychoanalyse, die einem eigenständigen wissenschaftstheoretischen Selbstverständnis und Erkenntnisprozess folgend unbewusste individuelle und überindividuelle, kulturspezifische Subjektivitätsmomente wie auch biologische Determinanten seelischen Erlebens und Verhaltens berücksichtigt, führt zur Formulierung dreier Dimensionen des dialektischen Prinzips der Psychoanalyse, die sich im Bemühen um die Gestaltung triangulär organisierter Verständigungsprozesse als hilfreich erweisen können. / Based on the theory that the behavior of „difficult“ children is a result of a socio-cultural evolution that has adversely affected the inner-psychological process of triangulation and, based on the school of thought of purposive-rational organizational structures and that of institution-specific forms of communication and action, along with the altered professional self-understanding of individual teachers – noneof which have yet to offer any satisfactory answers – the question arises in accordance with the potential of psychoanalysis concerning the possibilities for educators in the constitution of a school as a ‚triadic space’, dyadically characterized and triadically structured to support the constructive psycho-social realm of experience in childhood development. Oriented on the psychoanalytical theorem of triangularity, the analysis initially adresses the varied provenience of three concepts influencing the socializationtheoretically and psychoanalytically. In the context of a central target, this methodic approach proves to be only slightly helpful when outlining a comprehensive pedagogical concept to reinforce childhood triangular psychological structures. The subsequent discussion of the problems addressed on the slides of ‚cultural-theorist-oriented’ psychoanalysis, following an independent epistemological self-understanding and cognitive process, taking unconscious individual and supraindividualculture-specific moments of subjectivity as well as biological determinants of emotional experience and behavior into consideration, leads to the formulation of tree dimensions of the dialectic principle of psychoanalysis that might prove to be helpful when attempting to configure triangularly organized processes of understanding.
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Sistema de Engenharia Kansei para apoiar a descrição da visão do produto no contexto do Gerenciamento Ágil de Projetos de produtos manufaturados / Kansei Engineering System to support product vision description in the context of Agile Project Management of manufactured products.Ferreira Junior, Lucelindo Dias 23 January 2012 (has links)
O Gerenciamento Ágil de Projetos é uma abordagem útil para projetos com alto grau de complexidade e incerteza. Duas de suas características são: o envolvimento do consumidor nas tomadas de decisão sobre o projeto do produto; e, o uso de uma visão do produto, artefato que representa e comunica as características prioritárias e fundamentais do produto a ser desenvolvido. Há métodos para apoiar a criação da visão do produto, mas eles apresentam deficiências em operacionalizar o envolvimento do consumidor final. Por outro lado, existe a Engenharia Kansei, uma metodologia que permite capturar as necessidades de um grande número de consumidores e relacioná-las a características do produto. Este trabalho apresenta um estudo aprofundado da metodologia da Engenharia Kansei e analisa como essa pode ser útil para apoiar a descrição da visão do produto, no contexto do Gerenciamento Ágil de Projetos de produtos manufaturados. Em seguida, para verificar essa proposição, apresenta o desenvolvimento de um Sistema de Engenharia Kansei baseado na Teoria de Quantificação Tipo I, Aritmética Fuzzy, e Algoritmos Genéticos, testado para o projeto de uma caneta voltada a alunos de pós-graduação. Para execução do projeto foi utilizado um conjunto de métodos e procedimentos, tais como: revisão bibliográfica sistemática; desenvolvimento matemático; desenvolvimento computacional; e, estudo de caso. Analisa-se o Sistema de Engenharia Kansei proposto, e os resultados no caso aplicado, para averiguar seu potencial. Indica evidencias que o Sistema de Engenharia Kansei é capaz de gerar requisitos sobre configurações de produtos segundo a perspectiva do consumidor potencial, e que essas configurações são úteis para a formulação da visão do produto e na evolução desta visão no decorrer do projeto de produto. / The Agile Project Management is a useful approach for projects with high degree of complexity and uncertainty. Two of its singularities are: costumer involvement in decision making about the product design; and the use of a product vision, an artifact that represents and communicates the fundamental and high-priority features of the product to be developed. There are methods to support the creation of the product vision, but they have shortcomings in operationalizing the costumer involvement. On the other hand, there is the Kansei Engineering, a methodology to capture the needs of a large number of consumers and correlate them to product features. This paper presents a detailed study of the Kansei Engineering methodology and analyzes how this can be useful to support the description of the product vision, in the context of Agile Project Management of manufactured products. Then, to verify this proposition, it presents the development of a Kansei Engineering System based on Quantification Theory Type I, Fuzzy Arithmetic and Genetic Algorithms, tested for the design of a pen aimed at graduate students. To implement the project we used a set of methods and procedures, such as systematic literature review, mathematical development, computational development, and case study. It analyzes the proposed Kansei Engineering System and the results in the case study applied, to ascertain their potential. Evidence indicates that Kansei Engineering System is capable of generating requirements on product configurations from the perspective of the potential consumer, and that these configurations are useful for the description of the product vision and for the progression of this vision during the project of the product.
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Les relations non-contractuelles de travail : essai sur le tiers au contrat / The non-contractual labor relations : an essay on the third partyPiekut, Emmanuel 08 December 2016 (has links)
En raison de la fragmentation du processus productif et de la concentration des entreprises, des tiers sont susceptibles de s’immiscer dans l’exécution du contrat de travail. Le droit du travail en tient compte partiellement, en leur octroyant des prérogatives et en leur imposant des obligations semblables à celles de l’employeur. Au fil de l’analyse, émergent deux figures aux fonctions distinctes : le tiers utilisateur et le tiers organisateur. Ils ont la faculté d’établir une relation de travail avec un salarié sans qu’aucun contrat de travail ne les lie à celui-ci. Ils sont en outre amenés à préserver et protéger une relation de travail à laquelle ils ne sont pas parties grâce à des mécanismes de garantie ou de responsabilité. En découle une dispersion des droits et obligations de l’employeur ; l’idée d’un employeur unique est même remise en cause. N’est-ce pas le signe d’un dépassement du contrat de travail ? Sont-ce les prémices de relations non-contractuelles de travail ? Est-on à l’orée d’un changement de paradigme en droit du travail ? À ces multiples interrogations, la présente étude tente d’apporter des réponses. / Due to the fragmentation of the production process and corporate concentration, third parties are likely to interfere with the performance of the employment contract. The labor law take them partially into account by granting them prerogatives and imposing them similar obligations to those of the employer. Throughout this analysis, two figures emerge with distinct functions: the “user” third party and the “organizer” third party. They are able to establish a working relationship with an employee without any labor contract that binds them to him. They can also preserve and protect a working relationship in which they are not parties through mechanisms of guarantee or liability. As a result, the rights and obligations of the employer are dispersed; the idea of a single employer is even questioned. Isn’t it the sign that the employment contract is overwhelmed? Is it the beginning of non-contractual labor relations? Are we on the edge of a change of paradigm in labor law? To these many questions, this study attempts to provide answers.
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