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Marques-da-Silva, Antonio Hermes. "Gradient test under non-parametric random effects models." Thesis, Durham University, 2018. http://etheses.dur.ac.uk/12645/.
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The gradient test proposed by Terrell (2002) is an alternative to the likelihood ratio, Wald and Rao tests. The gradient statistic is the result of the inner product of two vectors — the gradient of the likelihood under null hypothesis (hence the name) and the result of the difference between the estimate under alternative hypothesis and the estimate under null hypothesis. Therefore the gradient statistic is computationally less expensive than Wald and Rao statistics as it does not require matrix operations in its formula. Under some regularity conditions, the gradient statistic has χ2 distribution under null hypothesis. The generalised linear model (GLM) introduced by Nelder & Wedderburn (1972) is one of the most important classes of statistical models. It incorporates the classical regression modelling and analysis of variance either for continuous response and categorical response variables under the exponential family. The random effects model extends the standard GLM for situations where the model does not describe appropriately the variability in the data (overdispersion) (Aitkin, 1996a). We propose a new unified notation for GLM with random effects and the gradient statistic formula for testing fixed effects parameters on these models. We also develop the Fisher information formulae used to obtain the Rao and Wald statistics. Our main interest in this thesis is to investigate the finite sample performance of the gradient test on generalised linear models with random effects. For this we propose and extensive simulation experiment to study the type I error and the local power of the gradient test using the methodology developed by Peers (1971) and Hayakawa (1975). We also compare the local power of the test with the local power of the tests of the likelihood ratio, of Wald and Rao tests.
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LeBlanc, Denis R. "Density and recharge effects during the Cape Cod natural-gradient tracer test." Thesis, Massachusetts Institute of Technology, 2001. http://hdl.handle.net/1721.1/84242.
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Eklund, Karin, and Malin Engström. "Comparison between two different cryoprotectants for human sperm, with emphasis on survival." Thesis, Uppsala University, Department of Medical Biochemistry and Microbiology, 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-9287.
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The increasing number of patients undergoing treatment with assisted reproductive techniques (ART) during the past years have led to the need of developing different methods for separation of spermatozoa that can be used for different fertilisation procedures and for freezing. Cryopreservation of spermatozoa includes preparation, freezing, storage and thawing.
In this study two different cryomedia (Cryo Protec I and Cryo Protec II) for human spermatozoa were compared. The main outcome was spermsurvival rate for spermatozoa after freezing. Sperm viability was assessed using the Hypo-osmotic swelling test which is based on osmolality.
A total of 86 samples of semen were used in this study (Cryo Protec I=38, Cryo Protec II=48). The survival rate between the two cryomedia did not differ much but Cryo Protectant I showed a small increase in survival for the spermatozoa after freezing. The Hypo-osmotic swelling test also showed similar values of viable spermatozoa for the two cryomedia both before and after freezing.
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Růžičková, Kateřina. "Mezidruhové interakce v mokřadním společenstvu v závislosti na vodním režimu: dlouhodobý test stress-gradient hypotézy." Master's thesis, Česká zemědělská univerzita v Praze, 2016. http://www.nusl.cz/ntk/nusl-258647.
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The Stress-gradient hypothesis predicates a change of interspecies relations from negative to positive according to the stress gradient. The basic assumption is that the presence of one species (the facilitator) makes the growth of other species easier. In this study was determined based on the 5years experiment, whether the interspecies interactions (i.e. the importance of facilitation and competition) changes according to the hydrological conditions. Three wetland species (Calamagrostis canescens, Carex elongata and Deschampsia cespitosa) were planted in experimental pots with the presence and absence of the dominant species (Carex elata). The hydrological gradient (= the stress gradient) was simulated by three types of hydrological conditions: dry, fluctuating and wet. The success of the species within the specific conditions was correlated with the fitness-related characteristics of the plants including the biomass, the number of ramets and the height of the plants. Following hypotheses were tested: i) at a low intensity of stress (with the wet treatment), the C. elata represents a competitor for other species. On the other hand, at a high intensity of stress (with the dry treatment), the C. elata represents a facilitator, making it easier to the other coexisting species to grow. This presumption was confirmed only with the D. cespitosa, which was more successful under dry treatment with the presence of a dominant species, which facilitated it. With the other two species the change of interspecific relations was not observed and the relationships remained negative. Furthermore the results showed, that in the dry treatment with the presence of a dominant species, there was a lower intensity of competition among the coexisting species. The experiment showed, that the interactions of particular species with dominant species can vary according to the stress gradient. The hydrological gradient also influences the character and intensity of interactions among the species.
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Bui, Hanh. "A COMPARISON OF TWO COMMERCIAL STRIPS WITH PREDEFINED ANTIBIOTIC CONCENTRATION GRADIENTS FOR SUSCEPTIBILITY TESTING OF PERIODONTAL BACTERIAL PATHOGENS." Master's thesis, Temple University Libraries, 2013. http://cdm16002.contentdm.oclc.org/cdm/ref/collection/p245801coll10/id/216515.
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Oral BiologyM.S.
Objectives: Systemic antibiotics are generally recognized as providing a beneficial impact in treatment of both aggressive and chronic periodontitis. Since strains of periodontal pathogens among periodontitis patients may vary in their antibiotic drug resistance, the American Academy of Periodontology recommends antimicrobial susceptibility testing of suspected periodontal pathogens prior to administration of systemic periodontal antibiotic therapy, to reduce the risk of a treatment failure due to pathogen antibiotic resistance. E-test and MIC Test Strip assays are two in vitro antimicrobial susceptibility testing systems employing plastic- and paper-based, respectively, carriers loaded with predefined antibiotic gradients covering 15 two-fold dilutions. To date, no performance evaluations have been carried out comparing the Etest and MIC Test Strip assays in their ability to assess the in vitro antimicrobial susceptibility of periodontal bacterial pathogens. As a result, the purpose of this study was to compare the in vitro performance of E-test and MIC Test Strip assays in assessing minimal inhibitory concentration (MIC) values of four antibiotics frequently utilized in systemic periodontal antibiotic therapy against 11 fresh clinical subgingival isolates of the putative periodontal pathogen, Prevotella intermedia/ nigrescens, and to compare the distribution of P. intermedia/ nigrescens strains identified with interpretative criteria as "susceptible" and "resistant" to each of the four antibiotics using MIC values determined by the two antimicrobial susceptibility testing methods. Methods: Standardized cell suspensions, equivalent to a 2.0 McFarland turbidity standard, were prepared with 11 fresh clinical isolates of P. intermedia/nigrescens, each recovered from the subgingival microbiota of United States chronic periodontitis subjects, and plated onto to the surfaces of culture plates containing enriched Brucella blood agar. After drying, pairs of antibiotic-impregnated, quantitative, gradient diffusion strips from two manufacturers (E-test, bioMérieux, Durham, NC, USA, and MIC Test Strip, Liofilchem s.r.l., Roseto degli Abruzzi, Italy) for amoxicillin, clindamycin, metronidazole, and doxycycline were each placed apart from each other onto the inoculated enriched Brucella blood agar surfaces, so that an antibiotic test strip from each manufacturer was employed per plate against each P. intermedia/ nigrescens clinical isolate for antibiotic susceptibility testing. After 48-72 hours anaerobic jar incubation, individual MIC values for each antibiotic test strip against P. intermedia/nigrescens were read in μg/ml at the point where the edge of the bacterial inhibition ellipse intersected with the antibiotic test strip. MIC50, MIC90, and MIC range were calculated and compared for each of the test antibiotics, with essential agreement (EA) values determined per test antibiotic for the level of outcome agreement between two antimicrobial susceptibility testing methods. In addition, the identification of antibiotic "susceptible" and "resistant" strains among the P. intermedia/nigrescens clinical isolates was determined for each test antibiotic using MIC interpretative criteria from the MIC interpretative standards developed by the European Committee on Antimicrobial Susceptibility Testing (EUCAST) for gram-negative anaerobic bacteria for amoxicillin, clindamycin, and metronidazole findings, and from the French Society of Microbiology breakpoint values for anaerobic disk diffusion testing for doxycycline data. Results: For amoxicillin, higher MIC50 and MIC90 values against the P. intermedia/ nigrescens strains were found with the MIC Test Strip assay than with E-test strips, resulting in a relatively low EA value of 45.5% between the two susceptibility testing methods. A higher percentage of amoxicillin "resistant" P. intermedia/nigrescens strains (72.7%) were identified by MIC Test Strips as compared to E-test strips (54.5%), although both methods found the same proportion of amoxicillin "susceptible" strains (27.3%). For clindamycin, both susceptibility testing methods provided identical MIC values (EA value = 100%), and exactly the same distributions of "susceptible" and "resistant" strains of P. intermedia/nigrescens. For metronidazole, only very poor agreement (EA value = 9.1%) was found between the two susceptibility testing methods, with MIC Test Strips exhibiting markedly higher MIC50 and MIC90 values against P. intermedia/nigrescens as compared to E-test strips. However, the distribution of "susceptible" and "resistant" P. intermedia/ nigrescens were identical between the two susceptibility testing methods. For doxycycline, relatively good agreement (EA value = 72.7%) was found in MIC concentrations between the two susceptibility testing methods, although generally lower MIC values were associated with MIC Test Strips. In addition, identical distributions of "susceptible" and "resistant" P. intermedia/nigrescens were provided by both susceptibility testing methods. Conclusions: Relative to MIC values measured against periodontal strains of P. intermedia/nigrescens, MIC Test Strips gave higher MIC values with amoxicillin and metronidazole, equal MIC values with clindamycin, and lower MIC values with doxycycline, as compared to MIC values measured with the E-test assay. Relative to the identification of antibiotic "susceptible" periodontal P. intermedia/ nigrescens strains, both susceptibility testing methods provided identical findings, suggesting that both methods appear to be interchangeable for clinical decision making in regard to identification of antibiotic-sensitive strains of periodontal P. intermedia/nigrescens. However, for epidemiologic surveillance of drug susceptibility trends, where exact MIC values are important to track over time, the relatively higher proportion of non-exact MIC differences between the two susceptibility testing methods argues against using them interchangeably. Instead, one or the other method should be used consistently for such studies. Further comparative studies of the E-test and MIC Test Strip assays are indicated using other periodontopathic bacterial species besides P. intermedia/ nigrescens, and to assess the reproducibility of MIC values provided by both in vitro susceptibility testing methods over time.
Temple University--Theses
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Thompson, Megan Elizabeth Dove. "Fabrication and Testing of a Heat Exchanger Module for Thermoelectric Power Generation in an Automobile Exhaust System." Thesis, Virginia Tech, 2013. http://hdl.handle.net/10919/19233.
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Thermoelectric generators (TEGs) are currently a topic of interest in the field of energy harvesting for automobiles. In applying TEGs to the outside of the exhaust tailpipe of a vehicle, the difference in temperature between the hot exhaust gases and the automobile coolant can be used to generate a small amount of electrical power to be used in the vehicle. The amount of power is anticipated to be a few hundred watts based on the temperatures expected and the properties of the materials for the TEG. This study focuses on developing efficient heat exchanger modules for the cold side of the TEG through the analysis of experimental data. The experimental set up mimics conditions that were previously used in a computational fluid dynamics (CFD) model. This model tested several different geometries of cold side sections for the heat exchanger at standard coolant and exhaust temperatures for a typical car. The test section uses the same temperatures as the CFD model, but the geometry is a 1/5th scaled down model compared to an full-size engine and was fabricated using a metal-based rapid prototyping process. The temperatures from the CFD model are validated through thermocouple measurements, which provide the distribution of the temperatures across the TEG. All of these measurements are compared to the CFD model for trends and temperatures to ensure that the model is accurate. Two cold side geometries, a baseline geometry and an impingement geometry, are compared to determine which will produce the greater temperature gradient across the TEG.
Master of Science
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Afonso, Rodríguez Verónica [Verfasser], and M. [Akademischer Betreuer] Weber. "Electromagnetic design, implementation and test of a superconducting undulator with a transverse gradient field amplitude / Verónica Afonso Rodríguez. Betreuer: M. Weber." Karlsruhe : KIT-Bibliothek, 2015. http://d-nb.info/1079594981/34.
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Vargas, Tiago Moreira. "Estatística gradiente: teoria assintótica de alta ordem e correção tipo-Bartlett." Universidade de São Paulo, 2013. http://www.teses.usp.br/teses/disponiveis/45/45133/tde-13062013-163845/.
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Obtemos uma expansão assintótica da função de distribuição sob a hipótese nula da estatística gradiente para testar hipóteses nulas compostas na presença de parâmetros de perturbação. Esta expansão é derivada utilizando uma rota Bayesiana baseada no argumento de encolhimento descrito em Ghosh e Mukerjee (1991). Usando essa expansão, propomos uma estatística gradiente corrigida por um fator de correção tipo-Bartlett, que tem distribuição qui-quadrado até um erro de ordem o(n-1) sob a hipótese nula. A partir disso, determinamos fórmulas matriciais e algébricas que auxiliam na obtenção da estatística gradiente corrigida em modelos lineares generalizados com dispersão conhecida e desconhecida. Simulações de Monte Carlo são apresentadas. Finalmente, discutimos a obtenção de regiões de credibilidade via inversão da estatística gradiente. Caracterizamos as densidades a priori, matching priors, que asseguram propriedades de cobertura frequentista acuradas para essas regiões.We obtain an asymptotic expansion for the null distribution function of the gradient statistic for testing composite null hypotheses in the presence of nuisance parameters. The expansion is derived using a Bayesian route based on the shrinkage argument described in Ghosh and Mukerjee (1991). Using this expansion, we propose a Bartlett-type corrected gradient statistic, which has a chi-square distribution up to an error of order o(n1) under the null hypothesis. Also, we determined matrix and algebraic formulas that assist in obtaining Bartett-type corrected statistic in generalized linear models with known and unknown dispersion. Monte Carlo simulations are presented. Finally, we obtain credible regions based by the inversion of gradient statistic. We characterize priori densities, matching priors, that ensure accurate frequentist coverage properties for these regions.
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Pedroza, Moises. "Automating Telemetry Tracking Systems Operational Tests." International Foundation for Telemetering, 2001. http://hdl.handle.net/10150/606471.
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International Telemetering Conference Proceedings / October 22-25, 2001 / Riviera Hotel and Convention Center, Las Vegas, NevadaAutomating Telemetry Tracking Systems Operational Readiness Tests is a concept that was introduced at White Sands Missile Range in the early 1980’s. The idea was to determine the condition of a Telemetry Tracking System in a reliable manner in a short time as possible. A series of RF and Servo Tests designed to determine the condition of a Telemetry Tracking System was implemented using HP BASIC. The latest personal computers are faster and have more storage capacity plus the capability to be programmed in higher level languages such as C/C++ and LabView. This technology makes it easier to automate system tests. Many of these tests need to be conducted just prior to supporting a mission. Some tests are required to be performed on mobile systems after moving the system from one location to another, especially if the move was over long distances and rugged terrain. Tests such as G/T are conducted before each mission because it yields accurate information on the Figure of Merit, or, System Sensitivity. Noise Figure Measurements are more difficult to perform to determine the System Sensitivity since modern RF Subsystems have pre-amplifiers with Noise Figures of less than 1.0 dB. The “down-sizing” of personnel increases the possibility of failure in mission support scenarios due to the many critical readiness tests needed to assess the Telemetry Tracking Systems. Also, conventional test methods can be time consuming and are subject to human error. This paper describes four critical tests that have been automated to improve reliability of the test data and decrease the amount of time required to conduct the tests. The “C/C++” language was used to write the automation programs. More tests will be automated later.
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Pelser, Alida Yonanda. "Adaptation of trees to the urban environment : Acacia karroo in Potchefstroom, South Africa / by Alida Yonanda Pelser." Thesis, North-West University, 2006. http://hdl.handle.net/10394/1550.
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Baldeyrou-Bailly, Armelle. "Etude expérimentale et modélisation de la stabilité des phyllosilicates soumis à un fort gradient thermique. Test dans le contexte du site géothermique de Soultz-sous-Forêts." Phd thesis, Université Louis Pasteur - Strasbourg I, 2003. http://tel.archives-ouvertes.fr/tel-00009986.
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Les phyllosilicates hydratés tels que les argiles sont à ce jour mal contraints thermodynamiquement. Leur domaine de stabilité, en particulier vis-à-vis de la température, est mal connu ; il est même inexistant pour certains auteurs, pour qui les argiles sont métastables. Nous utilisons un protocole expérimental dans lequel une succession d'équilibres locaux entre un fluide et des minéraux en précipitation se met en place le long d'un gradient thermique (Goffé et al., 1987). Nous obtenons ainsi une succession de minéraux néoformés à l'équilibre avec le fluide et la température, desquels nous déduisons les champs de stabilité thermique des différents assemblages minéralogiques. Les expériences ont été menées dans des systèmes chimiques simples : Mg-Al-Si-H2O (MASH), K-Al-Si-H2O (KASH), et K-Mg-Al-Si-H2O (KMASH). Les séquences de cristallisation observées le long du gradient thermique sont les mêmes lorsque les capsules contenant le matériel de départ sont interverties par rapport au gradient thermique. Cette « réversibilité » des expériences montre que les séquences de cristallisation sont bien l'expression d'un équilibre local. On observe, avec l'augmentation de température (de 200 à 350°C), les successions suivantes : smectite dioctaédrique → smectite trioctaédrique ; kaolinite → donbassite → chlorite trioctaédrique ; smectite → illite → muscovite ; ou encore kaolinite → illite + smectite → donbassite ; successions minéralogiques communément observées dans les systèmes hydrothermaux. Ces séquences expérimentales permettent de développer un modèle thermodynamique des phyllosilicates hydratés qui tient compte de l'évolution de leur état d'hydratation en fonction de la température. Ce modèle permet de mettre en évidence les champs de stabilité des argiles entre 200 et 300°C. Le dynamisme chimique et minéralogique mis en évidence dans ces systèmes expérimentaux est utilisé pour rendre compte des dissolutions/précipitations pouvant avoir lieu entre le fluide chaud et les épontes de granite dans le site de géothermie (Roche Chaude Fracturée) de Soultz-sous-Forêts, dont la pérennité dépend des éventuels changements de morphologie du réseau poreux lié à la fracturation. On constate expérimentalement que les feldspaths et les smectites forment l'ensemble du volume des silicates qui risquent le plus de précipiter, en plus des carbonates déjà décrits dans des études antécédentes et dont nous nous sommes affranchis dans cette étude.
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Bailly, Armelle. "Etude expérimentale et modélisation de la stabilité des phyllosilicates soumis a un fort gradient thermique : Test dans le contexte du site géothermique de Soultz-sous-Forêts." Université Louis Pasteur (Strasbourg) (1971-2008), 2003. https://publication-theses.unistra.fr/public/theses_doctorat/2003/BAILLY_Armelle_2003.pdf.
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Les phyllosilicates hydratés tels que les argiles sont à ce jour mal contraints thermodynamiquement. Leur domaine de stabilité, est mal connu ; il est même inexistant pour certains auteurs, pour qui les argiles sont métastables. Nous utilisons un protocole expérimental dans lequel une succession d'équilibres locaux entre un fluide et des minéraux en précipitation se met en place le long d'un gradient thermique. Les expériences ont été menées dans les systèmes chimiques : Mg-Al-Si-H2O (MASH), K-Al-Si-H2O (KASH), et K-Mg-Al-Si-H2O (KMASH). Les séquences de cristallisation observées le long du gradient thermique sont les mêmes lorsque les capsules contenant le matériel de départ sont interverties par rapport au gradient thermique. Les séquences de cristallisation sont bien l'expression d'un équilibre local. On observe, avec l'augmentation de température (de 200 à 350ʿC), les successions suivantes : smectite dioctaédrique ? smectite trioctaédrique ; kaolinite ? donbassite ? chlorite trioctaédrique ; smectite ? illite ? muscovite ; ou encore kaolinite ? illite + smectite ? donbassite ; successions communément observées dans les systèmes hydrothermaux. Ces séquences permettent de développer un modèle thermodynamique des phyllosilicates hydratés qui tient compte de l'évolution de leur état d'hydratation en fonction de la température. Ce modèle met en évidence les champs de stabilité des argiles entre 200 et 300ʿC. Le dynamisme chimique et minéralogique mis en évidence dans ces systèmes expérimentaux est utilisé pour rendre compte des dissolutions/précipitations pouvant avoir lieu entre le fluide chaud et les épontes de granite dans le site de géothermie de Soultz-sous-Forêts, dont la pérennité dépend des éventuels changements de morphologie du réseau poreux lié à la fracturation. Les feldspaths et les smectites forment l'ensemble du volume des silicates qui risquent le plus de précipiter, en plus des carbonates déjà décrits dans des études antécédentesThermodynamic data of hydrated phyllosilicates, in particular clay minerals are not well known. The stability fields of these minerals are not well determined; following some authors they even do not exist. We have developed an experimental approach, in which a sequence of local equilibrium states between a fluid and minerals take place in a closed gold cell along a strong thermal gradient. The experiments were conducted in the chemical systems : Mg-Al-Si-H2O (MASH), K-Al-Si-H2O (KASH), and K-Mg-Al-Si-H2O (KMASH). The sequences of crystallization observed along the thermal gradient are the same if one exchanges the position of the cells containing the initial reacting materials with respect to the thermal gradient end-members. The crystallization sequences correspond to local equilibrium states. Following the temperature increase (from 200 to 350ʿC) one observes the following sequences : dioctahedral smectite ? trioctahedral smectite; kaolinite ? donbassite ? trioctahedral chlorite; smectite ? illite ? muscovite ; or even kaolinite ? illite + smectite ? donbassite ; commonly observed in hydrothermal systems. They allow to develop a thermodynamic model for hydrated phyllosilicates, taking into account their hydration state as a function of temperature. This model shows the stability fields of clay minerals between 200 and 350ʿC. The chemical and mineralogical dynamics showed in these experimental systems has been applied to predict the possible dissolutions and/or precipitations which may take place between the circulated hot fluid and the geothermal granitic reservoir in the geothermal system at Soultz-sous-Forêts. These processes may affect the duration of the geothermal reservoir, as a function of evolution in the morphology of the porosity. Our experimental approach shows that feldspars and smectites are forming the major part of the total volume of silicates which may precipitate in addition to carbonates already described in previous studies
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Magalh?es, Felipe Henrique Alves. "Testes em modelos weibull na forma estendida de Marshall-Olkin." Universidade Federal do Rio Grande do Norte, 2011. http://repositorio.ufrn.br:8080/jspui/handle/123456789/18639.
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Previous issue date: 2011-12-28Universidade Federal do Rio Grande do Norte
In survival analysis, the response is usually the time until the occurrence of an event of interest, called failure time. The main characteristic of survival data is the presence of censoring which is a partial observation of response. Associated with this information, some models occupy an important position by properly fit several practical situations, among which we can mention the Weibull model. Marshall-Olkin extended form distributions other a basic generalization that enables greater exibility in adjusting lifetime data. This paper presents a simulation study that compares the gradient test and the likelihood ratio test using the Marshall-Olkin extended form Weibull distribution. As a result, there is only a small advantage for the likelihood ratio test
Em an?lise de sobreviv?ncia, a vari?vel resposta e, geralmente, o tempo at? a ocorr?ncia de um evento de interesse, denominado tempo de falha, e a principal caracter?stica de dados de sobreviv?ncia e a presen?a de censura, que ? a observa??o parcial da resposta. Associados a essas informa??es, alguns modelos ocupam uma posi??o de destaque por sua comprovada adequa??o a v?rias situa??es pr?ticas, entre os quais ? poss?vel citar o modelo Weibull. Distribui??es na forma estendida de Marshall-Olkin oferecem uma generaliza??o de distribui??es b?sicas que permitem uma flexibilidade maior no ajuste de dados de tempo de vida. Este trabalho apresenta um estudo de simula??o que compara duas estat?sticas de teste, a da Raz?o de Verossimilhan?as e a Gradiente, utilizando a distribui??o Weibull em sua forma estendida de Marshall-Olkin. Como resultado, verifica-se apenas uma pequena vantagem para estat?stica da Raz?o de Verossimilhancas
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Carneiro, H?rica Priscila de Ara?jo. "Testes de hip?teses em modelos de sobreviv?ncia com Fra??o de cura." Universidade Federal do Rio Grande do Norte, 2012. http://repositorio.ufrn.br:8080/jspui/handle/123456789/18644.
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Previous issue date: 2012-08-14Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior
Survival models deals with the modeling of time to event data. However in some situations part of the population may be no longer subject to the event. Models that take this fact into account are called cure rate models. There are few studies about hypothesis tests in cure rate models. Recently a new test statistic, the gradient statistic, has been proposed. It shares the same asymptotic properties with the classic large sample tests, the likelihood ratio, score and Wald tests. Some simulation studies have been carried out to explore the behavior of the gradient statistic in fi nite samples and compare it with the classic statistics in diff erent models. The main objective of this work is to study and compare the performance of gradient test and likelihood ratio test in cure rate models. We first describe the models and present the main asymptotic properties of the tests. We perform a simulation study based on the promotion time model with Weibull distribution to assess the performance of the tests in finite samples. An application is presented to illustrate the studied concepts
Modelos de sobreviv?ncia tratam do estudo do tempo at? a ocorr?ncia de um evento. Contudo em algumas situa??es, uma propor??o da popula??o pode n?o estar mais sujeita a ocorr?ncia deste evento. Modelos que tratam desta abordagem s?o chamados de modelos de fra??o de cura. Existem poucos estudos na literatura sobre testes de hip?teses aplicados a modelos de fra??o de cura. Recentemente foi proposta uma nova estat?stica de teste, denominada estat?stica gradiente que possui distribui??o assint?tica equivalente a das estat?sticas usuais. Alguns estudos de simula??o v?m sendo desenvolvidos no sentido de explorar caracter?sticas dessa nova estat?stica e comparar com as estat?sticas cl?ssicas, aplicadas a diferentes modelos. Este trabalho tem como principal objetivo estudar e comparar o desempenho do teste gradiente e do teste da raz?o de verossimilhan?as, em modelos de fra??o de cura. Para isso descrevemos caracter?sticas do modelo e apresentamos os principais resultados assint?ticos dos testes. Consideramos um estudo de simula??o com base no modelo de tempo de promo??o com distribui??o Weibull, para avaliar o desempenho dos testes em amostras finitas. Uma aplica??o e realizada para ilustrar os conceitos estudados
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Bosworth, Kyle Judson. "Health Monitoring of the Veterans' Glass City Skyway: Vibrating Wire Strain Gage Testing, Study of Temperature Gradients and a Baseline Truck Test." Connect to Online Resource-OhioLINK, 2007. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=toledo1197693985.
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Thesis (M.S.)--University of Toledo, 2007.Typescript. "Submitted as partial fulfillment of the requirements for the Master of Science in Civil Engineering." "A thesis entitled"--at head of title. Bibliography: leaves 86-87.
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Kayael, Burak. "An Investigation Of The Leak-off Tests Conducted In Oil And Natural Gas Wells Drilled In Thrace Basin." Master's thesis, METU, 2012. http://etd.lib.metu.edu.tr/upload/12614030/index.pdf.
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This study aims to analyze the leak-off tests carried out in the Thrace Basin of Turkey by Turkish Petroleum Corporation and find any relationship that may exist between leak-off test results and drilled formations as well as drilling parameters, such as mud weight, depth.
The analysis of 77 leak-off tests indicated that there is no close correlation between the mud weight of test fluid and equivalent mud weight (fracture gradient) if the test is carried out within impermeable sections. On the other hand, the correlation between mud weight and equivalent mud weight increase while running the test within permeable-productive zones. It is also found that the leak-off test results are not dependent on the depth but the formation to be tested.
The analyzed leak-off test results from Thrace Basin showed that the fracture gradient is not the limiting factor to set the casing of any section unless a gas show is observed during drilling operation which occurred only in 5 wells out of 78 wells
analyzed.
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Hilbig, David [Verfasser], Dietmar [Akademischer Betreuer] [Gutachter] Knipp, Veit [Gutachter] Wagner, Werner [Gutachter] Bergholz, Thomas [Gutachter] Henning, and Friedrich [Gutachter] Fleischmann. "Characterization of shape and functionality of optical components by gradient based transmission test / David Hilbig ; Gutachter: Veit Wagner, Dietmar Knipp, Werner Bergholz, Thomas Henning, Friedrich Fleischmann ; Betreuer: Dietmar Knipp." Bremen : IRC-Library, Information Resource Center der Jacobs University Bremen, 2016. http://d-nb.info/1122825366/34.
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SILVA, Priscila Gonçalves da. "Inferência e diagnóstico em modelos não lineares Log-Gama generalizados." Universidade Federal de Pernambuco, 2016. https://repositorio.ufpe.br/handle/123456789/18637.
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Young e Bakir (1987) propôs a classe de Modelos Lineares Log-Gama Generalizados (MLLGG) para analisar dados de sobrevivência. No nosso trabalho, estendemos a classe de modelos propostapor Young e Bakir (1987) permitindo uma estrutura não linear para os parâmetros de regressão. A nova classe de modelos é denominada como Modelos Não Lineares Log-Gama Generalizados (MNLLGG). Com o objetivo de obter a correção de viés de segunda ordem dos estimadores de máxima verossimilhança (EMV) na classe dos MNLLGG, desenvolvemos uma expressão matricial fechada para o estimador de viés de Cox e Snell (1968). Analisamos, via simulação de Monte Carlo, os desempenhos dos EMV e suas versões corrigidas via Cox e Snell (1968) e através da metodologia bootstrap (Efron, 1979). Propomos também resíduos e técnicas de diagnóstico para os MNLLGG, tais como: alavancagem generalizada, influência local e influência global. Obtivemos, em forma matricial, uma expressão para o fator de correção de Bartlett à estatística da razão de verossimilhanças nesta classe de modelos e desenvolvemos estudos de simulação para avaliar e comparar numericamente o desempenho dos testes da razão de verossimilhanças e suas versões corrigidas em relação ao tamanho e poder em amostras finitas. Além disso, derivamos expressões matriciais para os fatores de correção tipo-Bartlett às estatísticas escore e gradiente. Estudos de simulação foram feitos para avaliar o desempenho dos testes escore, gradiente e suas versões corrigidas no que tange ao tamanho e poder em amostras finitas.
Young e Bakir (1987) proposed the class of generalized log-gamma linear regression models (GLGLM) to analyze survival data. In our work, we extended the class of models proposed by Young e Bakir (1987) considering a nonlinear structure for the regression parameters. The new class of models is called generalized log-gamma nonlinear regression models (GLGNLM). We also propose matrix formula for the second-order bias of the maximum likelihood estimate of the regression parameter vector in the GLGNLM class. We use the results by Cox and Snell (1968) and bootstrap technique [Efron (1979)] to obtain the bias-corrected maximum likelihood estimate. Residuals and diagnostic techniques were proposed for the GLGNLM, such as generalized leverage, local and global influence. An general matrix notation was obtained for the Bartlett correction factor to the likelihood ratio statistic in this class of models. Simulation studies were developed to evaluate and compare numerically the performance of likelihood ratio tests and their corrected versions regarding size and power in finite samples. Furthermore, general matrix expressions were obtained for the Bartlett-type correction factor for the score and gradient statistics. Simulation studies were conducted to evaluate the performance of the score and gradient tests with their corrected versions regarding to the size and power in finite samples.
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Chowdhary, Girish. "Concurrent learning for convergence in adaptive control without persistency of excitation." Diss., Georgia Institute of Technology, 2010. http://hdl.handle.net/1853/37243.
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Model Reference Adaptive Control (MRAC) is a widely studied adaptive control methodology that aims to ensure that a nonlinear plant with significant modeling uncertainty behaves like a chosen reference model. MRAC methods attempt to achieve this by representing the modeling uncertainty as a weighted combination of known nonlinear functions, and using a weight update law that ensures weights take on values such that the effect of the uncertainty is mitigated. If the adaptive weights do arrive at an ideal value that best represent the uncertainty, significant performance and robustness gains can be realized. However, most MRAC adaptive laws use only instantaneous data for adaptation and can only guarantee that the weights arrive at these ideal values if and only if the plant states are Persistently Exciting (PE). The condition on PE reference input is restrictive and often infeasible to implement or monitor online. Consequently, parameter convergence cannot be guaranteed in practice for many adaptive control applications. Hence it is often observed that traditional adaptive controllers do not exhibit long-term-learning and global uncertainty parametrization. That is, they exhibit little performance gain even when the system tracks a repeated command.
This thesis presents a novel approach to adaptive control that relies on using current and recorded data concurrently for adaptation. The thesis shows that for a concurrent learning adaptive controller, a verifiable condition on the linear independence of the recorded data is sufficient to guarantee that weights arrive at their ideal values even when the system states are not PE. The thesis also shows that the same condition can guarantee exponential tracking error and weight error convergence to zero, thereby allowing the adaptive controller to recover the desired transient response and robustness properties of the chosen reference models and to exhibit long-term-learning. This condition is found to be less restrictive and easier to verify online than the condition on persistently exciting exogenous input required by traditional adaptive laws that use only instantaneous data for adaptation. The concept is explored for several adaptive control architectures, including neuro-adaptive flight control, where a neural network is used as the adaptive element. The performance gains are justified theoretically using Lyapunov based arguments, and demonstrated experimentally through flight-testing on Unmanned Aerial Systems.
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Niamchaona, Wichian. "Modélisation de l'influence des défauts de surface sur le comportement en fatigue de nuances d'acier innovantes." Thesis, Université Clermont Auvergne (2017-2020), 2019. http://www.theses.fr/2019CLFAC086.
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L’innovation de l’industrie métallurgique des aciers pour le secteur automobile passe par la fabrication de nuances d’acier à haute résistance telle que le grade CP800. Les nuances d’acier sont très sensibles, du point de vue de leur comportement en fatigue, à la présence d’un défaut de surface comme ceux générés par la mise en forme des pièces ou par la découpe des tôles. Des défauts de plusieurs types et de différentes tailles, similaires à ceux rencontrés lors du poinçonnage ou de l’emboutissage des tôles, ont été reproduits par électroérosion sur des éprouvettes de la nuance d’acier CP800. Ces éprouvettes font l’objet de notre étude en fatigue sur les plans numérique et expérimental. La modélisation de l’influence de ces défauts en fatigue utilise les deux approches globale et de type plan critique de la fatigue multiaxiale, et avec prise en compte du gradient des contraintes.La simulation numérique vise à établir les champs des contraintes et leurs gradients au voisinage des défauts analysés expérimentalement. La prise en compte des gradients des contraintes permet aux critères de fatigue multiaxiaux une prévision du comportement réel en fatigue beaucoup plus juste de cette nuance d’acier en présence de défauts de surface. Prendre en compte l’influence du gradient de contrainte est indispensable pour une prévision correcte de la limite de fatigue du matériau à haute résistance en présence d’un défaut de petite tailleThe steel manufacturers develop nowadays high strength steels as CP800 grade for automotive applications for the purpose of lightening vehicles. Such steels are strongly sensitive from the fatigue behaviour point of view to the surface defects generated by metal forming or cutting of steel sheets. Surface defects of different types and sizes were machined by electroerosion on CP800 specimens so that they are similar to the surface defects observed on steel sheets after stamping or cutting. The present study deals with the numerical and the experimental fatigue behaviour simulation of these specimens.The defect influence modelisation about the steel fatigue behaviour uses either the critical plane approach or the integral approach in multiaxial fatigue.The stress gradient influence contributes also to the fatigue life prediction of the defective simples.The numerical simulation aims to assess stress states and stress gradient fields within the tested specimens in the vicinity of their own surface defects. Accounting for stress gradients strongly improves the ability of multiaxial fatigue criteria to accurately predict the actual fatigue resistance of defective specimens. It shows also that multiaxial criteria have to be calibrated over fatigue test results with high stress gradients to properly predict the fatigue behaviour of high strength steel with surface small defect
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Gulib, Fahad. "Constitutive models and finite elements for plasticity in generalised continuum theories." Thesis, University of Edinburgh, 2018. http://hdl.handle.net/1842/33277.
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The mechanical behaviour of geomaterials (e.g. soils, rocks and concrete) under plastic deformation is highly complex due to that fact that they are granular materials consisting of discrete non-uniform particles. Failure of geomaterials is often related to localisation of deformation (strain-localisation) with excessive shearing inside the localised zones. The microstructure of the material then dominates the material behaviour in the localised zones. The formation of the localised zone (shear band) during plastic deformation decreases the material strength (softening) significantly and initiates the failure of the material. There are two main approaches to the numerical modelling of localisation of deformation in geomaterials; discrete and continuum. The discrete approach can provide a more realistic material description. However, in the discrete approach, the modelling of all particles is complicated and computationally very expensive for a large number of particles. On the other hand, the continuum approach is more flexible, avoids modelling the interaction of individual particles and is computationally much cheaper. However, classical continuum plasticity models fail to predict the localisation of deformation accurately due to loss of ellipticity of the governing equations, and spurious mesh-dependent results are obtained in the plastic regime. Generalised plasticity models are proposed to overcome the difficulties encountered by classical plasticity models, by relaxing the local assumptions and taking into account the microstructure-related length scale into the models. Among generalised plasticity models, Cosserat (micropolar) and stain-gradient models have shown significant usefulness in modelling localisation of deformation in granular materials in the last few decades. Currently, several elastoplastic models are proposed based on Cosserat and strain-gradient theories in the literature. The individual formulation of the models has been examined almost always in isolation and are paired with specific materials in a mostly arbitrary fashion. Therefore, there is a lack of comparative studies between these models both at the theory level and in their numerical behaviour, which hinders the use of these models in practical applications. This research aims to enable broader adoption of generalised plasticity models in practical applications by providing both the necessary theoretical basis and appropriate numerical tools. A detailed comparison of some Cosserat and strain-gradient plasticity models is provided by highlighting their similarities and differences at the theory level. Two new Cosserat elastoplastic models are proposed based on von Mises and Drucker- Prager type yield function. The finite element formulations of Cosserat and strain-gradient models are presented and compared to better understand their advantages and disadvantages regarding numerical implementation and computational cost. The finite elements and material models are implemented into the finite element program ABAQUS using the user element subroutine (UEL) and an embedded user material subroutine (UMAT) respectively. Cosserat finite elements are implemented with different Cosserat elastoplastic models. The numerical results show how the Cosserat elements behaviour in the plastic regime depends on the models, interpolation of displacement and rotation and the integration scheme. The effect of Cosserat parameters and specific formulations on the numerical results based on the biaxial test is discussed. Two new mixed-type finite elements as well as existing ones (C1, mixed-type and penalty formulation), are implemented with different strain-gradient plasticity models to determine the numerical behaviour of the elements in the plastic regime. A detailed comparison of the numerical results of Cosserat and strain-gradient elastoplastic models is provided considering specific strain-localisation problems. Finally, some example problems are simulated with both the Cosserat and strain-gradient models to identify their applicability.
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Garcin, Patrick. "Etude expérimentale du comportement hydraulique et mécanique des géosynthétiques bentonitiques." Grenoble 1, 1997. http://www.theses.fr/1997GRE10015.
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Les geosynthetiques bentonitiques (gb) associent les proprietes mecaniques des geosynthetiques a la faible permeabilite d'une argile particuliere: la bentonite. Les proprietes de celle-ci conferent aux gb une permeabilite de l'ordre de 10#-#1#1 m/s. Les geosynthetiques bentonitiques (gb) sont des barrieres hydrauliques separant un milieu polluant ou non du sol. Nous avons montre que les gb ne remplacent pas systematiquement les couches d'argile compactee, mais sont une alternative interessante. Certains tests specifiques a la bentonite se revelent utiles pour caracteriser les gb, mais une approche geotechnique du comportement du composite est necessaire. Dans la partie hydraulique, bien que les vitesses de transfert de l'eau dans les gb soient tres faibles, nous avons montre que les essais de permeabilite pouvaient etre interpretes par la loi de darcy dans la gamme de gradients hydrauliques utilisee. Les resultats sont donnes sous la forme de coefficients de permittivite ou de permeabilite, plus usuels en geotechnique que les coefficients de diffusion. La mesure de la permeabilite des gb sans defaut dans differents permeametres a long terme, (duree d'essai atteignant une annee), a permis de definir une methodologie pour la mesure de permeabilite a charge variable (duree minimale de saturation ou de consolidation, charge hydraulique identique en debut de palier de consolidation). Des essais en cuve de grandes dimensions simulent des conditions reelles d'utilisation (par exemple les recouvrements de les). La partie mecanique developpe deux aspects: le cisaillement des interfaces rencontrees dans les dispositifs d'etancheite par geosynthetique bentonitique (degb) et le cisaillement interne. La methodologie et les conditions d'essais utilisees pour le cisaillement des geosynthetiques sont applicables aux gb. En revanche, notre etude a montre la difficulte de mesurer la resistance au cisaillement interne des gb renforces par aiguilletage. Imposer un plan de cisaillement entre les deux nappes de geotextiles est une operation delicate et il est preferable de tester les caracteristiques du degb dans son ensemble, en laissant le glissement se produire suivant le plan le plus defavorable
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Pavlíčková, Lucie. "Metoda bootstrap a její aplikace." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2009. http://www.nusl.cz/ntk/nusl-228541.
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The diploma thesis describes the bootstrap method and its applications in the estimate accuracy statement, in the confidence intervals generation and in the testing of statistical hypotheses. Further the method of the discrete probability estimation of the categorical quantity is presented, making use the gradient of the quasi-norm hereof distribution. On concrete examples the bootstrap method is applied in the confidence intervals forming of the categorical quantity probability function. The diploma thesis was supported by the project of MŠMT of the Czech Republic no. 1M06047 "Centre for Quality and Reliability of Production", by the grant of Grant Agency of the Czech Republic (Czech Science Foundation) reg. no. 103/08/1658 "Advanced optimum design of composed concrete structures" and by the research plan of MŠMT of the Czech Republic no. MSM0021630519 "Progressive reliable and durable structures".
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DeCesar, Richard T. "Natural gradient tracer tests in a highly fractured soil /." Full text open access at:, 1987. http://content.ohsu.edu/u?/etd,143.
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Pavlíčková, Lenka. "Fitování rozdělení pravděpodobnosti pro aplikace." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2012. http://www.nusl.cz/ntk/nusl-230140.
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The diploma thesis describes the bootstrap method and its applications in the confidence intervals generation, in the testing of statistical hypotheses and in the regression analysis. We present the confidence interval for individual value. Further the method of discrete probability estimation of the categorical quantity is presented, making use the gradient and the line estimate.
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Calisti, Matteo. "Differential calculus in metric measure spaces." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2020. http://amslaurea.unibo.it/21781/.
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L'obbiettivo di questa tesi è la definizione del calcolo differenziale e dell'operatore di Laplace in spazi metrici di misura. Nel primo capitolo vengono introdotte le definizioni e proprietà principali degli spazi metrici di misura mentre nel secondo quelle riguardanti le funzioni lipschitziane e la derivata metrica di curve assolutamente continue. Nel terzo capitolo quindi viene definito il concetto di p-supergradiente debole e di conseguenza la classe di Sobolev S^p. Nel quarto capitolo viene poi studiata la generalizzazione del concetto di differenziale di f applicato al gradiente di g che da luogo a due funzioni che in generale risultano diverse, ma se coincidono lo spazio verrà detto q-infinitesimamente strettamente convesso.
Vengono quindi dimostrate alcune regole della catena per per queste due funzioni attraverso la dualità fra lo spazio S^p e un opportuno spazio di misure dette q-piani test. In particolare mediante l'introduzione del funzionale energia di Cheeger e il suo flusso-gradiente sarà possibile associare un piano di trasporto al gradiente di una funzione in S^p. Nel quinto capitolo viene definito il p-laplaciano e le regole di calcolo provate precedentemente saranno usate per provare quelle per il laplaciano. Verranno poi definiti gli spazi infitesimamente di Hilbert: in questo caso il laplaciano assume un solo valore e risulta linearmente dipendente da g e si dimostra un'identificazione tra differenziali e gradienti. Nell'ultima parte del quinto capitolo infine viene mostrata un'applicazione del calcolo differenziale in spazi metrici di misura al gruppo di Heisenberg, considerandolo uno spazio metrico di misura munito della metrica di Korany e la misura di Lebesgue. Nella prima parte si mostra che il laplaciano metrico coincide con quello subriemanniano. Viene poi considerata nella seconda parte la sottovarietà {x=0} e si dimostra come il laplaciano metrico sia diverso da quello differenziale.
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Lemonte, Artur Jose. "Estatística gradiente e refinamento de métodos assintóticos no modelo de regressão Birnbaum-Saunders." Universidade de São Paulo, 2010. http://www.teses.usp.br/teses/disponiveis/45/45133/tde-26102010-123617/.
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Rieck & Nedelman (1991) propuseram um modelo de regressão log-linear tendo como base a distribuição Birnbaum-Saunders (Birnbaum & Saunders, 1969a). O modelo proposto pelos autores vem sendo bastante explorado e tem se mostrado uma ótima alternativa a outros modelos propostos na literatura, como por exemplo, os modelos de regressão Weibull, gama e lognormal. No entanto, até o presente momento, não existe nenhum estudo tratando de refinamentos para as estatísticas da razão de verossimilhanças e escore nesta classe de modelos de regressão. Assim, um dos objetivos desta tese é obter um fator de correção de Bartlett para a estatística da razão de verossimilhanças e um fator de correção tipo-Bartlett para a estatística escore nesse modelo. Estes ajustes melhoram a aproximação da distribuição nula destas estatísticas pela distribuição qui-quadrado de referência. Adicionalmente, objetiva-se obter ajustes para a estatística da razão de verossimilhanças sinalizada. Tais ajustes melhoram a aproximação desta estatística pela distribuição normal padrão. Recentemente, uma nova estatística de teste foi proposta por Terrell (2002), a qual o autor denomina estatística gradiente. Esta estatística foi derivada a partir da estatística escore e da estatística de Wald modificada (Hayakawa & Puri, 1985). A combinação daquelas duas estatísticas resulta em uma estatística muito simples de ser calculada, não envolvendo, por exemplo, nenhum cálculo matricial como produto e inversa de matrizes. Esta estatística foi recentemente citada por Rao (2005): \"The suggestion by Terrell is attractive as it is simple to compute. It would be of interest to investigate the performance of the [gradient] statistic.\" Caminhando na direção da sugestão de Rao, outro objetivo da tese é obter uma expansão assintótica para a distribuição da estatística gradiente sob uma sequência de alternativas de Pitman convergindo para a hipótese nula a uma taxa de convergência de n^{-1/2} utilizando a metodologia desenvolvida por Peers (1971) e Hayakawa (1975). Em particular, mostramos que, até ordem n^{-1/2}, a estatística gradiente segue distribuição qui-quadrado central sob a hipótese nula e distribuição qui-quadrado não central sob a hipótese alternativa. Também temos como objetivo comparar o poder local deste teste com o poder local dos testes da razão de verossimilhanças, de Wald e escore. Finalmente, aplicaremos a expansão assintótica derivada na tese em algumas classes particulares de modelos.The Birnbaum-Saunders regression model is commonly used in reliability studies.We address the issue of performing inference in this class of models when the number of observations is small. Our simulation results suggest that the likelihood ratio and score tests tend to be liberal when the sample size is small. We derive Bartlett and Bartlett-type correction factors which reduce the size distortion of the tests. Additionally, we also consider modified signed log-likelihood ratio statistics in this class of models. Finally, the asymptotic expansion of the distribution of the gradient test statistic is derived for a composite hypothesis under a sequence of Pitman alternative hypotheses converging to the null hypothesis at rate n^{-1/2}, n being the sample size. Comparisons of the local powers of the gradient, likelihood ratio, Wald and score tests reveal no uniform superiority property.
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Bromfield, Michael. "Criteria for acceptable stick force gradients of a light aeroplane." Thesis, Brunel University, 2012. http://bura.brunel.ac.uk/handle/2438/6861.
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During the period 1980 to 2008 there were 359 fatal accidents involving UK registered light aeroplanes of which 36% occurred in visual meteorological conditions. In all, 216 lives were lost with accidents being attributed to the pilot 'failing to maintain proper control resulting in a stall or spin'. Dissimilar fatal stallrelated accident rates are evident for aeroplane makes & models of similar design. During the course of this programme of research, flight testing of two similar aeroplane models using a case study method showed marked differences in the variation of stick force with airspeed or stick force gradient in all flight conditions. This suggested that 'control feel' was a contributory factor towards the pilot’s failure to maintain proper control. Current certification standards for light aeroplanes rely upon the subjective assessment of stick force gradients by test pilots, requiring that substantial changes in airspeed are accompanied by clearly perceptible changes in stick force with no specified minimum gradient. This programme of research has been carried out to determine acceptable criteria for stick force gradients of a light aeroplane in all flight conditions. Criteria has been determined from flight tests of aeroplanes with different in-service safety records and subjective pilot workload assessment using simulated flying tasks with different stick force gradients performed by twenty GA pilots. Simulation tests indicated that pilot mental demand increased significantly (p > 0.05) when stick force gradient was reduced to ‘zero’, representing an aeroplane with neutral longitudinal static stability. A predictive model has been developed to estimate stick force gradients for a light aeroplane in any flight condition under quasi-static, longitudinal, non-manoeuvring flight and 1-g loading conditions. The model builds upon previous published work limited to cruising flight, and enables the estimation of stick forces and gradients due to high lift devices in the climb and landing condition by consideration of the combined effects of wing loading, CG, elevator gearing, flaps and elevator trim setting. Implemented using MATLAB, the model has been validated by comparing with flight test results for the case study aeroplanes and showed mean differences of ±0.025 daN/kt. The predictive model should be used in preliminary aeroplane design to assess tendencies towards neutral stability in high workload, safety critical flight conditions such as the take-off and landing. In addition, the model should be used to analyse existing aeroplanes with comparatively low or neutral stick force gradients in safety critical flight phases and to predict the effects of changing CG and/or flap limits to increase stick force gradient and improve control feel. The combined results of these studies suggest that a minimum acceptable stick force gradient for a non-aerobatic light aeroplane in all flight conditions should be nonzero and between 0.10~0.13 daN/kt. A stable and predictable stick force variation with airspeed will ensure that any substantial deviation from trimmed airspeed is accompanied by a stick force change clearly perceptible to the pilot and also provide additional warning of the proximity to the stall. The use of specific criteria to complement qualitative test pilot opinion, will assist in confirming compliance and provide consistency with current standards for sailplanes/powered sailplanes and large commercial aeroplanes, both of which already have defined minimum acceptable gradients.
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Yan, Li. "Hydraulic gradient similitude method for geotechnical modelling tests with emphasis on laterally loaded piles." Thesis, University of British Columbia, 1990. http://hdl.handle.net/2429/31899.
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A study has been undertaken to evaluate and apply the hydraulic gradient similitude
method to geotechnical model testings. This method employs a high hydraulic gradient across granular soils to effectively increase self-weight stresses in the model. Testing principle and procedures are presented, and the factors affecting test results discussed. An apparatus (UBC-HGST) using this testing principle has been developed.
Three applications are presented in which the hydraulic gradient similitude method is evaluated, and the existing concepts and methods of analysis for the problems
studied are examined.
In the footing tests, it is found that the scaling laws implied in the hydraulic gradient
modelling test are satisfied, and are similar to those of the centrifuge modelling technique. Load-settlement curves are found to be similar to those in centrifuge tests. The test results illustrate the importance of the stress level in the load-settlement responses.
Terzaghi's bearing capacity formula is compared with the observed bearing capacities under different stress levels. It is found that due to the stress level effects,
the bearing capacity coefficient, Nγ, decreases linearly with footing width on the log-log scale which is in accordance with other model study and analytical results.
In the downhole and crosshole seismic tests, results are used to evaluate the empirical
equations that relate shear wave velocity and soil stresses in terms of field stress condition. It is found that although the various equations can predict the insitu shear wave velocity profile reasonably well, only the equation which is based on the significant
stresses in the wave propagation and particle motion directions can predict the variation of velocity ratio between the downhole and SH crosshole tests. It is also found that the stress ratio has some effects on the downhole (or SV crosshole) tests,
but not on the SH crosshole tests. This indicates that only the stress ratio in the plane of wave propagation is important to the shear wave velocity. Comparison between
the downhole and SH crosshole tests shows that the structure anisotropy was about 10% in terms of shear wave velocity. Prediction of Ko values using shear wave measurement is evaluated, and its practical difficulties are addressed.
In the laterally loaded pile tests, the pile response to static and cyclic loadings at various stress levels controlled by the hydraulic gradients is examined in terms of pile head response, pile bending moment and soil-pile interaction P-y curves. For the static loading, pile head response and bending moment are found to be significantly affected by the soil-pile relative stiffness, pile diameter, loading condition and pile head fixity. However, little effects of loading eccentricity and pile head fixity are found on the P-y curves. While pile diameter is found to have effects on the P-y curves at large pile deflection, its effects are negligible at small deflecton range. The effects of relative soil-pile stiffness on the P-y curves due to stress levels can be normalized by the soil modulus and pile diameter for the curves below 1 pile diameter, as computed by the plane strain finite element analysis. Two methods of generating P-y curves are suggested, and found to give satisfactory results as compared with the test data and the prediction given by API code (1987). For cyclic loading, different pile responses are observed in "one-way" as compared to "two-way" cyclic loading. The cyclic P-y curves are derived, and found to be highly nonlinear and hysteretic, and change with number of loading cycles. From these studies, it is shown that the hydraulic gradient similitude method provides a simple and inexpensive means of model testing for many geotechnical engineering problems and adds to the data base from which methods of analysis can be evaluated.Applied Science, Faculty of
Civil Engineering, Department of
Graduate
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Masmali, Ali Mohammed. "Development of a tear ferning test protocol and a new grading scale." Thesis, Cardiff University, 2010. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.646158.
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Poll, Tyler R. "Standards-Based Grading: A Correlational Study Between Grades and End-of-Level Test Scores." DigitalCommons@USU, 2019. https://digitalcommons.usu.edu/etd/7435.
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As students move from grade level to grade level and onto college, their grades have an impact on the number of opportunities available to students. The competition for entering college and earning a scholarship are at an all-time high and the grades students earn have a direct impact on future opportunities. Grading practices vary by teacher causing students’ grades to mean different things.
Standards-based grading practices focus on removing teacher bias and puts emphasis on the learning students can demonstrate. Students are given assessments to determine learning and are given multiple opportunities to show what they have learned. Emphasis is placed a student’s most current knowledge rather than an average of scores during the grading period.
This study focused on how student learning was impacted when secondary math, science, and language arts teachers use standards-based grading practices in their classrooms. Student learning was measured by term grades and end-of-level SAGE test scores. Results show students who attended a classroom with standards-based grades earned higher GPAs, performed better on the end-of-level test, and had more learning growth over the course of the school year, than their peers who participated in traditional grading classrooms.
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Barns, Gareth L. "On single well forced gradient tracer tests : implications of aquifer physical heterogeneity and tracer behaviour." Thesis, University of Sheffield, 2010. http://etheses.whiterose.ac.uk/1409/.
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Single well forced gradient tracer tests are a potential cost-effective approach to estimate in situ aquifer contaminant fate and transport parameters for use in natural attenuation assessments and remediation schemes. To date dipole flow tracer tests have been used to measure the conservative and hydraulic parameters of an aquifer, while push-pull tests are well characterised for use with biodegrading tracers. The effect of typical aquifer physical heterogeneity on the ability of single well tests to successfully estimate parameters has not yet been characterised. Also, the ability of single well tests to accurately and quickly measure aquifer parameters using tracer mixtures should be analysed. To investigate the effect of physical heterogeneity on single well tests scaled down ultraviolet imaging experiments were performed in a low profile box. Potential tracers for use in mixtures were investigated through column and batch experiments: Inorganic anions and fluorescein, inorganic cations, acetate and trichlorofluoroethene were considered to measure conservative transport parameters, cation exchange capacity, biodegradation potential and hydrophobic sorption respectively. Numerical modelling was used to simulate reactive tracer signals in single well forced gradient tests. Results suggest that dipole flow tracer tests are appropriate for measuring conservative transport parameters and the sorption of lowly retarded tracers, but are not highly suitable for biodegrading tracers. Tests could be performed with non-recirculating flow, allowing simpler modelling, if equal injection and extraction flow rates could be ensured. Push-pull tests are suitable for biodegrading tracers and moderate to highly retarded tracers. This limits the potential to use reactive tracer mixtures in these tests. Dipole flow tracer test breakthrough curves are highly susceptible to heterogeneity, and could be used to identify discrete permeability variations in aquifers. The effect of heterogeneity is not significant on push-pull test breakthrough curves, but seriously affects tracer plume migration. Inorganic anions provided the most reliable conservative tracer. Trichlorofluoroethene was found to be a suitable tracer to measure hydrophobic sorption. The biodegradation surrogate chosen for a field test should biodegrade similarly to the contaminant under study.
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Pereira, Deividi da Silva. "Estudo de gradientes térmicos e deformações em "whitetopping" ultradelgado." Universidade de São Paulo, 2001. http://www.teses.usp.br/teses/disponiveis/3/3138/tde-04072002-090959/.
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Propiciado pela construção de uma pista experimental inteiramente instrumentada com medidores de deformação e de temperatura na Cidade Universitária, este trabalho buscou o entendimento de inúmeros fatores intervenientes no desempenho do whitetopping ultradelgado, recente técnica de manutenção de pavimentos asfálticos com a utilização de delgadas placas de concreto, sob tráfego característico urbano, em condições tipicamente tropicais de uso, sobre uma pequena espessura de concreto asfáltico remanescente de fresagem. Com o intuito de nortear o problema em questão, além da revisão bibliográfica, foram realizados levantamentos periódicos das condições estruturais e funcionais deste pavimento; leituras contínuas de temperaturas e deformações obtidas por meio de um sistema automatizado de captação de dados junto aos instrumentos colocados no interior das placas; caracterização dos gradientes térmicos presentes nas placas durante as diferentes estações climáticas do ano. Foram realizadas provas de carga, estáticas e dinâmicas, com intuito de verificar os reais níveis de deformação aos quais as placas estariam sujeitas quando da interação com o tráfego; posteriormente, realizou-se modelagem numérica por meio de um programa de elementos finitos objetivando uma comparação com os dados obtidos nas provas de carga, analisando inclusive o posicionamento da linha neutra neste pavimento composto. Por fim, em uma sucinta abordagem sobre as deflexões antes e depois da execução do whitetopping ultradelgado, observou-se o tipo de comportamento estrutural do pavimento nas condições em que o experimento foi realizado. Ao término da pesquisa, inferiu-se que os gradientes térmicos dependem de vários fatores climáticos que não somente a temperatura ambiente, importando também a irradiação solar, o número de horas de sol, a velocidade de crescimento e decréscimo da temperatura ambiente; os gradientes térmicos encontrados não são importantes para o acréscimo nos níveis de tensões nas placas, não alterando assim a vida à fadiga do whitetopping ultradelgado, considerada a magnitude destes gradientes, as diminutas dimensões das placas e ainda a presença de aderência na interface concreto e concreto asfáltico. Em provas de carga, concluiu-se que os valores de tensões obtidos em campo mantêm grandezas semelhantes com os provenientes de modelos numéricos e ainda observou-se o vasto potencial de utilização das provas dinâmicas. Dado o excelente desempenho observado nas condições do experimento, mesmo com as placas aderidas a uma delgada camada asfáltica, fator que diferentemente do relatado no exterior não comprometeu o desempenho, não foi possível fazer uma avaliação em termos funcionais do desempenho deste tipo de pavimento. Verificou-se a significativa redução nas deflexões após a execução das placas, visualizando inclusive a transferência de cargas entre sucessivas placas, quando mantida a integridade estrutural das demais camadas do pavimento.In this work, several factors affecting behavior and performance of ultra-thin whitetopping were evaluated taking advantage of a full scale experimental pavement, restored by applying such technique. Temperatures and thermal gradients in concrete thin slabs were evaluated by almost one year, comprising al the seasons. Load tests were carried out to allow strains measurements on concrete as well to define the deflection basins on whitetopped pavements. The experimental research has permitted to verify the dependence of thermal gradients on air temperature and solar radiation among other factors. It was observed that the thermal gradients practically do not affect behavior of the thin slabs. Stresses received from load tests compared to finite element generated stresses shown to maintain a good and closed relation. Due to good performance observed along the experiment it became not possible to establish patterns of functional performance. Expressive decrease of deflection level was observed over concrete overlays allowing to infer some load transfer on joints when the slabs are to be laid over non distressed old asphalt pavements.
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PRUDEN, AMY J. "BIODEGRADATION OF METHYL TERT -BUTYL ETHER." University of Cincinnati / OhioLINK, 2002. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1027943573.
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Aghaee, Ghaleshahi Nima. "Thermal Issues in Testing of Advanced Systems on Chip." Doctoral thesis, Linköpings universitet, Institutionen för datavetenskap, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-120798.
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Many cutting-edge computer and electronic products are powered by advanced Systems-on-Chip (SoC). Advanced SoCs encompass superb performance together with large number of functions. This is achieved by efficient integration of huge number of transistors. Such very large scale integration is enabled by a core-based design paradigm as well as deep-submicron and 3D-stacked-IC technologies. These technologies are susceptible to reliability and testing complications caused by thermal issues. Three crucial thermal issues related to temperature variations, temperature gradients, and temperature cycling are addressed in this thesis. Existing test scheduling techniques rely on temperature simulations to generate schedules that meet thermal constraints such as overheating prevention. The difference between the simulated temperatures and the actual temperatures is called temperature error. This error, for past technologies, is negligible. However, advanced SoCs experience large errors due to large process variations. Such large errors have costly consequences, such as overheating, and must be taken care of. This thesis presents an adaptive approach to generate test schedules that handle such temperature errors. Advanced SoCs manufactured as 3D stacked ICs experience large temperature gradients. Temperature gradients accelerate certain early-life defect mechanisms. These mechanisms can be artificially accelerated using gradient-based, burn-in like, operations so that the defects are detected before shipping. Moreover, temperature gradients exacerbate some delay-related defects. In order to detect such defects, testing must be performed when appropriate temperature-gradients are enforced. A schedule-based technique that enforces the temperature-gradients for burn-in like operations is proposed in this thesis. This technique is further developed to support testing for delay-related defects while appropriate gradients are enforced. The last thermal issue addressed by this thesis is related to temperature cycling. Temperature cycling test procedures are usually applied to safety-critical applications to detect cycling-related early-life failures. Such failures affect advanced SoCs, particularly through-silicon-via structures in 3D-stacked-ICs. An efficient schedule-based cycling-test technique that combines cycling acceleration with testing is proposed in this thesis. The proposed technique fits into existing 3D testing procedures and does not require temperature chambers. Therefore, the overall cycling acceleration and testing cost can be drastically reduced. All the proposed techniques have been implemented and evaluated with extensive experiments based on ITC’02 benchmarks as well as a number of 3D stacked ICs. Experiments show that the proposed techniques work effectively and reduce the costs, in particular the costs related to addressing thermal issues and early-life failures. We have also developed a fast temperature simulation technique based on a closed-form solution for the temperature equations. Experiments demonstrate that the proposed simulation technique reduces the schedule generation time by more than half.
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Buck, Eric L. "Ecosystem Restoration and Subtropical Seagrass Fishes: Insights into Salinity Effects from Habitat Selection and Preference Tests." Scholarly Repository, 2011. http://scholarlyrepository.miami.edu/oa_theses/239.
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The work of this Master of Science thesis project is an analysis of salinity effects on nearshore epifauna along the western shore of Biscayne Bay in southeast Florida, USA. Field collection surveys have found a high probability of occurrence of bigeye mojarra (Eucinostomus havana) in salinities near 25 ppt. In a salinity gradient observation experiment test subjects of the same species and size class were also observed more frequently at 24 ppt. In this analysis presence and abundance patterns found in field surveys were compared with behavioral results obtained in the observation tank. This apparatus provided insight into distribution patterns of the bigeye mojarra (Eucinostomus havana) and possible changes in distribution that may result from habitat changes in the future. Historically, the western shore of Biscayne Bay was more freshwater marsh than the mangrove dominated marine environment that prevails today. Changes to fresh water inputs into the Bay are planned through projects of the Comprehensive Everglades Restoration Plan (CERP). CERP is a joint Florida state and U.S. federal effort to redesign surface water flow through the canal system of South Florida, replenish the Everglades ecosystem, and restore a more natural quantity, timing, and distribution of flow into Biscayne and Florida Bays. Approved by the U.S. Congress as part of the Water Resources Development Act of 2000, CERP will be implemented by the South Florida Water Management District (SFWMD) and the U.S. Army Corps of Engineers (USACE). This plan is designed to restore the ecosystem from its freshwater core to the coastal wetlands recreating a condition close to that existing before the current system of flood control drainage canals was begun in 1903 and continued by the federal Central and Southern Florida Project in 1948 (www.evergladesplan.org). Changes are planned to divert a portion of canal flows to Biscayne Bay into coastal wetlands as sheet flow and surface runoff. Planned changes to freshwater delivery may change the habitat along the shoreline and thus the distribution of prey organisms living in this habitat. This may in turn affect predator fish important to local recreational and commercial fisheries as well as other predators such as wading birds. The analysis and prediction provided in this thesis work is important for better understanding the effects of restoration efforts on the Bay nearshore habitat and its condition as essential fish habitat, which is federally regulated by the Magnuson-Stevens Fishery Conservation and Management Act (Magnuson-Stevens, 1996). The distribution of small fish and invertebrate inhabitants of the nearshore environment and habitat environmental qualities have been recorded over the past five years from throw-trap surveys of the western shoreline of Biscayne Bay as part of a CERP-sponsored monitoring program. This pattern is correlated with salinity, but there may be other factors affecting the distribution of this species.
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Zhang, Yanjun [Verfasser]. "Der Piano Grading Test in der Klavierpädagogik Chinas : Entstehung - Inhalts- und Funktionsanalyse - Perspektiven / Yanjun Zhang." Frankfurt : Peter Lang GmbH, Internationaler Verlag der Wissenschaften, 2012. http://d-nb.info/1042467943/34.
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Henry, Dawn Therese. "Standards-based Grading: The Effect of Common Grading Criteria on Academic Growth." Bowling Green State University / OhioLINK, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=bgsu1522846892709392.
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Rivola, Maria. "Relazione tra profilo sensoriale, emozioni e gradimento: il caso studio del prosciutto cotto." Bachelor's thesis, Alma Mater Studiorum - Università di Bologna, 2016. http://amslaurea.unibo.it/10011/.
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Il prosciutto cotto è un alimento presente nella dieta degli italiani, che lo consumano più di ogni altro salume. Il D. M. del 21/09/2005, che ne disciplina produzione e vendita, lo classifica in tre diverse categorie merceologiche (Prosciutto cotto o Standard, Prosciutto cotto Scelto, Prosciutto cotto Alta Qualità). Il lavoro svolto presso il Dipartimento di Scienze e Tecnologie Agro-Alimentari dell’Università di Bologna su 92 consumatori di prosciutto cotto ha permesso di studiare abitudini, gusti, aspettative dei soggetti intervistati e di verificare la loro capacità di distinguere prosciutti cotti appartenenti alle differenti categorie. A tale scopo è stato progettato un questionario strutturato secondo il modello RATA con una sezione per valutare i profili emozionali dei prodotti in esame conforme al metodo EmoSemio. Il gruppo di consumatori intervistati era composto da soggetti con età compresa tra 19 e 70 anni, frequenza di consumo di prosciutto cotto pari a 1-3 volte al mese e maggior familiarità con l’Alta Qualità. I risultati ottenuti hanno evidenziato l’ottima capacità percettiva dei consumatori, che hanno descritto i campioni in modo analogo al panel di esperti, che in precedenza aveva valutato gli stessi campioni. La chiara discriminazione riscontrata da parte dei consumatori tra i prosciutti Standard e Alta Qualità, però, non sempre si è tradotta in una preferenza per il prodotto della categoria migliore. I risultati relativi alla valutazione dello stato emozionale erano in linea con il gradimento: per i prodotti più graditi l’intensità delle emozioni positive era più alta. Infine, quasi tutti gli attributi scelti dal panel sono stati compresi e valutati allo stesso modo dai consumatori, risultando efficaci e, talora, comunicabili. Questo studio ha contribuito a fornire gli elementi per la comprensione del profilo di gradimento del prosciutto cotto al consumo ed ha confermato l'utilità del metodo RATA e dell’EmoSemio.
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Camilo, Claudia Cristiane. "Implantes de alumina em gradiente funcional de porosidade recobertos com hidroxiapatita e biovidro: avaliação da osseointegração." Universidade de São Paulo, 2010. http://www.teses.usp.br/teses/disponiveis/18/18146/tde-17012011-160849/.
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Esta pesquisa tem como finalidade desenvolver implantes de alumina com núcleo denso e superfície gradualmente porosa (FGM) recobertos com materiais bioativos - hidroxiapatita e biovidro. Materiais porosos são estudados como solução para a osseointegração, porém apresenta déficit nas suas propriedades mecânicas. Estruturas bifásicas foram desenvolvidas por pesquisadores com o propósito de promover crescimento tecidual, sem afetar significativamente sua propriedade mecânica, no entanto ocorre delaminação. Neste trabalho é proposta uma estrutura em gradiente funcional que visa aprimorar as propriedades mecânicas conjugadas com a sinalização celular e com integração óssea. O tamanho, a morfologia de poros e também a porosidade são parâmetros fundamentais para boa resposta tecidual e integração do implante, pois afetam a viabilidade e a afinidade celular. Para essa finalidade a busca por uma espessura efetiva de porosidade se faz fundamental para alto desempenho do implante. Peças de alumina porosas infiltradas com materiais bioativos foram fabricadas e estudadas in vivo, em tíbias de ratos da raça Wistar durante 14, 18, 21 e 28 dias, para investigar a qualidade do crescimento de tecido ósseo. O estudo com implantes porosos recobertos foi realizado para avaliar e padronizar a superfície porosa do gradiente funcional. Os animais foram analisados com densidade mineral óssea (DMO), as tíbias foram caracterizadas na interface osso-implante e nos poros com histologia, com EDS-line-scan, com radiografias e com ensaios de cisalhamento. Implantes de alumina com 70% de porosidade foram comparados com recobrimento bioativo e sem recobrimento in vivo e ex-vivo. Nos resultados, os implantes recobertos aceleram o processo de osseointegração. Essa característica foi mais evidente no período de 28 dias de implantação com aumento de 24% na tensão de cisalhamento. Após validar uma superfície porosa e osseointegrável para a superfície do gradiente funcional, foram aplicadas técnicas diferenciadas para manufaturar peças com núcleo denso e superfície com gradiente de porosidade. As peças com FGM foram manufaturadas com a utilização de duas técnicas, dipping e co-prensagem e foram analisadas com microscopia eletrônica de varredura. Com o método de manufatura de co-prensagem foram obtidas peças com superfície gradualmente porosa, com transição de densificação contínua, sem delaminação. Os implantes de alumina em gradiente funcional com 70 % de porosidade na superfície mais externa, recobertos por bioativos apresentam potencial para aplicações em implantes ósseos ou dentários.The present thesis reports on the development of alumina implants with dense core and gradually porous surface (FGM) covered with bioactive materials, hydroxyapatite (HA) and bioactive glass. Porous materials have been studied to provide tissue ingrowth, however they strongly affect the mechanical properties of the implant. Biphasic structures have been developed by some researchers to promote tissue growth without affecting the mechanical properties, although delamination may occur. This study proposes a functional gradient structure to improve both the mechanical properties of the material and cell signaling. The size and morphology of the pores as well as their porosity are key parameters for good tissue response and implant integration, since they affect the viability and cell affinity, and an effective porosity thickness becomes essential for a high performance of the implant. Porous alumina implants coated with bioactive materials were fabricated and studied in vivo in rat tibia for 14, 18, 21, and 28 days to investigate the quality of bone tissue growth. The study of porous coated implants was performed to evaluate and standardize the porous surface of the functional gradient. The animals were examined with bone mineral density (BMD), the tibiae were characterized in the bone-implant interface and the pores were analyzed with histology, EDS line-scan, X-ray and shear tests. Alumina with 70% porosity was compared with and without bioactive coating in vivo and ex vivo. The results showed that the covered implants accelerated the osseointegration process. This characteristic is more evident within 28 days of deployment with a 24% increase in shear stress. After validating a porous and osteointegrated surface for the surface of the functional gradient, several techniques were applied to manufacture parts with dense core and surface with gradient of porosity. The pieces were manufactured with FGM using two techniques, dipping and co-pressing and were analyzed by scanning electron microscopy. The manufacturing method of co-pressing allowed obtaining pieces with gradually porous surface and continuous transition of densification without delamination. On the outermost surface, alumina implants with functional gradient and 70% porosity and coated with bioactive materials presented potential for application to bone or dental implants.
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Cederqvist, My. "Aspects of grading and assessing English as a foreign language : A qualitative study of teachers' experiences of the Swedish grading system." Thesis, Linnéuniversitetet, Institutionen för språk (SPR), 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:lnu:diva-58832.
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CHANUDET, MARIE. "Etude theorique et experimentale d'une structure acceleratrice a ondes progressives demontable pour des tests fort gradient (structure dite meccano)." Paris 6, 1996. http://www.theses.fr/1996PA066077.
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Pour que les collisionneurs lineaires du futur atteignent des energies de l'ordre du tev sur des longueurs raisonnables, une solution consisterait a utiliser des sections acceleratrices a fort gradient. Dans cette optique, la section prototype meccano a ete developpee au laboratoire de l'accelerateur lineaire afin de mettre en evidence les phenomenes physiques et technologiques lies a des champs electriques eleves dans des structures acceleratrices a ondes progressives. Cette these aborde le comportement du champ electromagnetique dans la section meccano sur le plan theorique par des simulations numeriques et des modelisations analytiques, sur le plan experimental par des mesures a faible et forte puissance. Les resultats obtenus sont analyses et compares. Classiquement, la representation d'une structure uniforme et infinie par des series de circuits resonnants rlc permet de retrouver les proprietes hf de base du mode fondamental. Pour une section finie, l'adaptation sur une onde progressive directe ou inverse de dephasage par cellule quelconque a ete simulee en termes de circuits. Alors, les variations de reflexion et transmission de la structure en fonction de la frequence ainsi qu'une methode de reglage des coupleurs ont pu etre modelisees puis verifiees experimentalement. Le comportement electromagnetique de chaque cavite de forme differente ainsi que de la structure dans son ensemble a ete etudie. Le mode fondamental et les premiers modes superieurs ont ete simules avec des codes bidimensionnels et tridimensionnels et mesures a basse puissance. L'adaptation hf de la phase, de l'amplitude et du taux de reflexion du mode accelerateur est exposee. Elle est en effet rendue delicate par les brusques changements de geometrie de la section. La structure a ete testee sous forte puissance. Des champs electriques limites de plus de 150mv/m ont pu etre realises. Des enseignements physiques et technologiques concernant l'evolution des brasures, des materiaux et surfaces des parois sous fort gradient ont ete tires
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Vitasse, Yann. "Déterminismes environnemental et génétique de la phénologie des arbres de climat tempéré : suivi des dates de débourrement et de sénescence le long d'un gradient altitudinal et en tests de provenances." Thesis, Bordeaux 1, 2009. http://www.theses.fr/2009BOR13788/document.
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Afin d’appréhender la réponse des forêts au changement climatique, la phénologie de six espèces d’arbres a été étudiée de 2005 à 2007 à la fois le long d’un gradient altitudinal (fournissant un gradient thermique d’environ 7°C), et en tests de provenances disposés à différentes altitudes. L’objectif était (i) de quantifier les variations phénotypiques des dates de débourrement et de sénescence in situ, (ii) de déterminer les variables climatiques à l’origine de ces patrons, notamment à l’aide de modèles phénologiques, et (iii) d’évaluer la variabilité génétique et la plasticité phénotypique de ces deux événements phénologiques. Nos résultats montrent que la température printanière affecte différentiellement les dates de débourrement des six espèces (de -1.9 jours /°C à -6.5 jours /°C respectivement pour le hêtre et le chêne) mais pas entre les populations d’une espèce. Concernant les dates de sénescence, nous avons mis en évidence que la température induit un fort décalage de cet événement chez le chêne et le hêtre (> 5 jours /°C), alors qu’aucun cline n’est détecté chez l’érable et le frêne. L’allongement de la saison de végétation en réponse à une augmentation de la température est ainsi principalement la conséquence d’une avance des dates de débourrement pour toutes les espèces, à l’exception du hêtre qui présente une plus forte sensibilité pour la sénescence. Les modèles phénologiques utilisés soulignent l’importance des températures printanières affectant les bourgeons en phase de quiescence, tandis que les températures froides hivernales susceptibles de lever la dormance des bourgeons ne semblent pas significativement influencer l’occurrence du débourrement. Concernant la sénescence, les modèles ont mis en évidence le rôle prépondérant de la température pour le chêne sessile et le hêtre, tandis que la photopériode et d’autres facteurs pourraient être impliqués chez le frêne et l’érable. Ainsi, les modèles prédisent que la durée de saison de croissance du chêne va augmenter plus rapidement que celle du hêtre dans les prochaines décennies, et que l’équilibre compétitif entre ces deux espèces en terme phénologique est susceptible d’évoluer vers des altitudes plus élevées. Enfin, nous avons mis en évidence que les différentes populations échantillonnées présentaient de fortes adaptations pour la phénologie et la croissance malgré leur proximité géographique. De plus, les normes de réaction obtenues démontrent, d’une part, l’existence d’une forte plasticité phénologique des espèces, et d’autre part que cette plasticité semble être une caractéristique intrinsèque de l’espèce. Ces résultats révèlent que les arbres ont des capacités adaptatives importantes concernant les traits phénologiques qui pourraient leur permettre, dans une certaine mesure, de faire face au réchauffement du climatTo assess the response of forests to climate change, the phenology of six tree species was monitored from 2005 to 2007 both along an altitudinal gradient (providing a thermal gradient of about 7 ° C), and in provenance trials at various altitudes. The aim was (i) to characterize phenological patterns of leaf unfolding and leaf senescence timings in situ, (ii) to determine climatic variables responsible for these patterns, in particular using phenological models, and (iii) to assess the genetic variability and phenotypic plasticity of these phenological events. Our results showed that spring temperature differentially affected the leaf unfolding dates of the six species, with significant disparity in responses among species (from -1.9 days / ° C to -6.5 days / ° C for beech and oak, respectively) but not between the populations of a given species. Regarding the dates of senescence, we highlighted that temperature induced a strong shift of this event for oak and beech (> 5 days / ° C), while no cline was detected for sycamore and ash. The lengthening the growing season in response to an increase in temperature is thus mainly the result of an advance in flushing dates for all species except beech, whose growing season length changes were greatly resulting from shifts in senescence. Phenological models stressed the importance of forcing temperatures (effective during bud quiescence period), while the chilling temperatures (effective during dormancy) did not appear to significantly influence the occurrence of leaf unfolding. Concerning senescence variations , the models highlighted the role of temperature for sessile oak and beech, while the photoperiod and other factors could be involved in the ash and maple. Thus, for oak, the models predicted that the length of growing season will extend faster than the one for beech in the coming decades, and that the phenological competitive balance between these two species will likely to evolve towards higher altitudes. Finally, we showed that the sampled populations showed strong adaptations in phenology and growth in spite of their geographical proximity. Moreover, the reaction norms indicated, first, the existence of a strong phenological plasticity of species, and second, that this plasticity seemed to be an intrinsic characteristic of the species. These results underline that trees have consequent inherent adaptive capacities in phenological traits which may enable them to cope with global warming. However, the differences in phenological sensitivities among species suggest that global warming will significantly affect the competitive balance of species
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Patrick, Christy M. "Educational Stakeholders' Perceptions during Grading Reform in One Middle School." Thesis, Lindenwood University, 2015. http://pqdtopen.proquest.com/#viewpdf?dispub=3736294.
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The purpose of this study was to analyze the factors influencing middle school grading reform. The study involved all stakeholders in one middle school community. Participants were surveyed to determine which standards-based grading practices were most welcomed among middle school students, parents, teachers, and administrators. Additionally, students’ perceived motivation levels when evaluated using standards-based grading practices were quantified and the necessary support needs of middle school teachers were identified as they attempted school-wide grading reform. Many are calling for school leaders to evaluate unreliable traditional grading methods and reform grading to a standards-based approach (Guskey, Swan, & Jung, 2011; Wormeli, 2013). For this reason, the survey items used in the study were based on the positive and negative outcomes of standards-based grading found in current research. The sample groups for the study included 137 middle school students, 148 parents, 25 teachers, and three administrators. Descriptive statistics were used to analyze the results of Likert-style survey items and open-ended questions. Findings indicated the most accepted grading changes among all stakeholders included allowing students multiple attempts to show the learning of a concept and providing for awareness and understanding of learning objectives. The teacher survey results revealed necessary support needs when attempting grading reform include the following: making grading decisions together as a faculty, communicating grading changes with parents, and allowing for time to implement grading changes correctly.
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Löfving, Jimmy. "Predicting essay grades for the Swedish national writing test based on the new grading scale A-F." Thesis, Uppsala universitet, Statistiska institutionen, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-384958.
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Based on the curriculum of 2011 a new grading scale ranging from A-F was introduced in the Swedish upper secondary school system. Previous research on similar data have focused on the earlier grading scale, and its crucial that the new circumstances are addressed to understand the impact on grading. Using 348 essays from the national writing test this study investigates the use of automated essay scoring as a way of grading in this new setting. Using various classication methods the models for younger students outperform the corresponding models for older students. This implies that it is harder to predict grades on essays written by older students. Based on the current data the result shows that with the new grading scale the use of automated essay scoring should be used with caution.
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Winton, Terry W. "Student and Teacher Perceptions of Standards-based Grading and Student Performance." Thesis, Lindenwood University, 2015. http://pqdtopen.proquest.com/#viewpdf?dispub=3728021.
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Assessing student learning has been part of education since the beginning of formalized schooling. Developments at the national, state, and local level have led to grading reforms over the past quarter century. The purpose of this study was to explore students’ and teachers’ perceptions of standards-based grading to determine if there was a significant difference on standardized tests scores between students graded using standards-based grading and students graded using traditional grading. Teachers and students from one Missouri high school were interviewed to determine their perceptions about standards-based grading. A stratified sample was utilized to select interviewees. Artifacts from the district were analyzed to determine the process in the implementation of standards-based grading. Quantitative data were obtained from the Missouri Department of Elementary and Secondary Education to compare the Missouri Assessment Performance (MAP) Index scores and means on end-of-course exams from the participating high school with Missouri students. A t-test was utilized to determine the difference between the two means. The data revealed teachers’ perceptions of standards-based grading were varied, with only two teachers who preferred standards-based grading. Student perceptions were more positive than those of teachers, with 50% of students who were interviewed preferring standards-based grading. Quantitative data revealed no statistically significant difference between the means on end-of-course exams of students assessed with standards-based grading and students assessed with traditional grading in five of the eight subject areas studied.
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Hill, Gerry R. "Impact of Teacher Attitudes on Implementation of a Standards-Based Grading System." Thesis, Piedmont College, 2019. http://pqdtopen.proquest.com/#viewpdf?dispub=13426348.
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The purpose of this phenomenological study was to examine the impact of teacher attitudes and to discover other factors that have an impact on the implementation of a standards-based grading program. This descriptive phenomenology features interviews of 25 educators from Georgia as well as other states and two foreign countries in order to collect their perspectives of the lived experience of the implementation process.
The findings of this study suggest that the attitudes teachers have regarding the implantation process of a standards-based grading program do have a significant impact on the process. Those participants who described themselves as having a positive attitude towards the transition tended to also describe experiencing a more successful implementation of the program. The converse was true as participants describing their experience as being controlled by a negative attitude towards the transition experienced less successful transitions to the standards-based grading program. The findings of this study suggest that school leaders play a vital role in creating a successful implementation process and that other factors such as the quality of professional development and the element of time impact the process.
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West, Gregory K. "The construct validity of the holistic writing score an analysis of the essay subtest of the College-Level Academic Skills Test /." Gainesville, FL, 1988. http://www.archive.org/details/constructvalidit00west.
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Shi, Feifei. "Comportement des tôles métalliques à gradient de propriété sous chargement dynamique." Thesis, Cachan, Ecole normale supérieure, 2015. http://www.theses.fr/2015DENS0035/document.
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Cette étude vise à bien comprendre puis à modéliser le comportement mécanique dans une large plage de vitesse de déformation des tôles d’acier austénitique AISI304 ayant subis un traitement d'attrition mécanique de la surface (SMAT). Ces tôles ainsi traités sont des matériaux multicouches avec un gradient de propriétés. Les principaux résultats obtenus sont résumés comme suit：(1) La sensibilité globale à la vitesse déformation des tôles d’acier austénitique AISI304 traités avec SMAT est caractérisée par des essais de double cisaillement sous chargements quasi-statiques et dynamiques, qui permet d’atteindre une grande déformation sans instabilité géométrique. Des essais de double cisaillement sous impact sont réalisés à l’aide des barres de Hopkinson de grande diamètre et un système d’attache qui a une même impédance acoustique que la barre. Une sensibilité significative a été révélée et on observe ce renforcement n’a pas induit une réduction importante de la ductilité.(2) Dans le but d’un meilleur dépouillement de ces essais de double cisaillement, leur conditions d’essai est analysé dans le détaillé. Le modèle numérique avec le système d’attache a été construit pour étudier l’influence du système d’attache au début de chargement. On trouve un effet limité pour les diverses conditions imparfaites des essais comme la souplesse de système d’attache, des champs mécaniques non-homogènes, l’état de non-équilibre, etc. Par contre, les études numérique et analytique ont démontré que l’hypothèse simple de petites perturbations habituellement utilisé pour le dépouillement de ces essais n’est pas suffisamment précise. La déformation Eulérien cumulée doit être utilisée pour obtenir un résultat numérique correct. A partir de ce résultat, la sensibilité à la vitesse déformation des tôles d’acier austénitique AISI304 traités avec SMAT obtenue expérimentalement a été retouchée.(3) Un modèle multicouche elasto-plastique en dommageable a été proposé pour décrire le comportement des tôles d’acier austénitique AISI304 traités avec SMAT. Les paramètres sont identifiées à partir des essai de traction. La partie elasto-plastique est calée par une loi d’écrouissage de type Ludwig. Par contre, les paramètres d’endommagement sont obtenus avec une méthode d’identification inverse sur la base de simulation numérique de ces essais de traction. Pour valider ce modèle multi-couche elasto-plastique dommageable, un essai d’indentation/perforation est réalisé sur des tôles d’acier austénitique AISI304 traités avec SMAT. Des simulations numériques correspondantes montres que ce modèle multi-couche elasto-plastique en dommageable une prédiction plutôt précise de ces essais de d’indentation/perforation.(4) Pour évaluer la performance anti-perforation des tôles d’acier austénitique AISI304 traités avec SMAT, des essais de perforation sous impact a été réalisés avec des barres de Hopkinson. Des simulations numériques de ces essais de perforation sous impact sont réalisées avec un modèle numérique comparable avec le cas quasi-statique. ́tant donne que la sensibilité globale à la vitesse déformation des tôles d’acier austénitique AISI304 traités avec SMAT est caractérisée par des essais de double cisaillement, la sensibilité à la vitesse a été introduite dans le modèle multi-couche elasto-plastique en dommageable. Le résultat numérique correspond bien à la mesure expérimentale, ce qui indique non seulement l’efficacité du modèle numérique mais aussi celle du modèle multicouche elasto-plastique en dommageableThis Ph.D dissertation aimed at the comprehensive understanding and the constitutive modeling of the mechanical behaviours of the surface mechanical attrition treatment (SMAT) treated AISI304 stainless steel sheet under a large range of loading rates. SMAT treated AISI304 stainless steel sheets are multi-layered functionally graded materials (FGM). The main research results and conclusions are summarized as followed:(1) The overall rate sensitivity SMAT treated AISI304 stainless steel sheet is characterized by the double shearing test under quasi-static and dynamic loading where a large strain can be achieved without geometry instability. Impact double shear test are performed with a large diameter Hopkinson bar system and an adapted equal-impedance clamping device. Significant rate sensitivity is found. It is also observed that such a rate enhancement does not induce an important reduction of the ductility.(2) In order to extract accurate material information from the double shear tests, their testing conditions are thoroughly analyzed using numerical simulation. Numerical models including clamping devices have been built to investigate the influence of this clamping device at the early stage of loading. A limited effect was found for various imperfect testing conditions such as the clamping device stiffness, non-homogeneous stress and strain fields, non-equilibrium state, etc. On the contrary, numerical and analytical study shows that the simple small strain assumption usually used in double shear tests are not accurate enough. Eulerian cumulated strain definition should be used to get consistent numerical results. From this finding, the experimental rate sensitivity obtained for the SMAT treated AISI304 stainless steel sheet are recalculated.(3) A multi-layers elastic plastic damageable constitutive model is proposed to model SMAT treated AISI304 stainless steel sheet. The parameters are identified using tensile testing results. The elastic plastic behavior is curve fitted with a simple Ludwig hardening model. However, the damage parameters should be identified using an inverse method on the basis of numerical simulation of these tensile tests. In order to validate this multi-layer elastic plastic damageable constitutive model, indentation/piercing tests on SMAT treated AISI304 stainless steel sheet are performed. Numerical simulation of this indentation/piercing tests is also realized. It is found that the identified multi-layer elastic plastic damageable constitutive model allows for a quite accurate prediction of the experimental piercing tests.(4) In order to evaluate the impact anti-piercing capacity of the SMAT treated AISI304 stainless steel sheet, the impact perforation tests using Hopkinson bar are carried out. Numerical simulation of these impact perforation tests are realized with a similar FEM model as the quasi-static case. As the rate sensitivity of SMAT treated AISI304 stainless steel sheet is experimentally characterized with double shear test, a rate sensitive multi-layer elastic plastic damageable constitutive model is introduced. The numerical results agree well with the experimental ones, which indicates the effectiveness of the numerical model as well as the rate sensitive multi-layer elastic plastic damageable constitutive model
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Laurenti, Karen Cristina. "Desenvolvimento de um biomaterial composto de poliuretano e microfibra de biovidro 45S5 em gradiente funcional para reparo de cartilagem articular: estudos in vitro e in vivo." Universidade de São Paulo, 2011. http://www.teses.usp.br/teses/disponiveis/18/18146/tde-02032012-175916/.
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A cartilagem articular é um tema amplamente discutido na literatura por meio de vários estudos e pesquisas. Com o presente estudo, busca-se uma proposta inovadora e original no uso de um biomaterial composto e o desenvolvimento de uma cartilagem artificial que aja como coxim elástico, apresentando características de gel fibro-reforçado com finalidade biomimética mecânica que imite o comportamento da cartilagem articular. Foi conceituado um implante que tivesse uma superfície tribológica para contato com a cartilagem do platô tibial e gradualmente se convertesse em região osteo-integrável para fixação mecânica no osso subcondral. Foi desenvolvido um biomaterial composto por poliuretano e microfibra de biovidro 45S5 em gradiente funcional que foi obtido e validado através de ensaios in vitro, microscopia eletrônica de varredura e análise histológica. Nos testes in vitro seja na condição de citotoxicidade direta ou indireta, notou-se que a quantidade de células foi estatisticamente semelhante ao controle negativo, e estatisticamente diferente do controle positivo indicando que o biomaterial composto de poliuretano e microfibra de biovidro 45S5 apresentou não toxicidade direta ou indireta da amostra e ainda promoveram o crescimento e o espalhamento celular, resultados que o habilitaram para a continuidade nos estudos com experimentos in vivo com coelhos. O material foi manufaturado para aplicação em defeitos osteocondrais de coelhos medindo 3mm de diâmetro e 4mm de profundidade que foi realizado na região central da tróclea femoral. Após períodos experimentais de 15, 30 e 90 dias as análises de microscopia eletrônica de varredura mostrou na região distal da superfície tribológica uma neo-formação de uma estrutura semelhante as trabéculas ósseas que foi considerada biomimética confirmadas por análises histológicas, e na região proximal à superfície tribológica a presença de tecido fibrocartilaginoso com condrócitos e ricamente vascularizado, validando com sucesso o conceito proposto para o implante.Articular cartilage has been widely discussed in the literature by means of several studies and researches. The present thesis reports on an innovative and original proposal to use a biomaterial compound and the development of an artificial cartilage that acts as a cushion rubber with characteristics of fiber-reinforced gel with biomimetic mechanical purpose mimicking the behavior of articular cartilage. An implant with a tribological surface for contact with the cartilage of the tibial plateau was designed. It should gradually turn into an osteo-integrable region for mechanical fixation in the subchondral bone. A biomaterial composed of polyurethane and bioglass microfiber in functional gradient was then developed and validated by scanning electron microscopy and histological analysis through in vitro tests. Under either direct or indirect cytotoxicity conditions, the tests showed that the amount of cells is statistically similar to negative control and statistically different from the positive control, indicating that the biomaterial composed of polyurethane and bioglass microfiber showed no direct or indirect toxicity and promoted cell growth and spreading. Such results allowed continuing the studies with in vivo experiments with rabbits. The material was manufactured for use in 3mm diameter and 4mm depth osteochondral defects in the central region of the femoral trochlea of rabbits. After experimental periods of 15, 30 and 90 days, the scanning electron microscopy analysis showed a neo-formation of a structure similar to trabecular bones on the tribological surface in the distal region. This neo-formation was considered biomimetic, confirmed by both histological analysis and the presence of richly vascularized fibrocartilaginous tissues with chondrocytes in the region proximal to the tribological surface.