Dissertations / Theses: 'Tests en cyclage'

1

Sadoun, Redha. "Intérêt d'une Source d'Energie Electrique Hybride pour véhicule électrique urbain - dimensionnement et tests de cyclage." Phd thesis, Ecole Centrale de Lille, 2013. http://tel.archives-ouvertes.fr/tel-00980484.

Full text

Abstract:

Actuellement, la principale source d'énergie embarquée dans les véhicules électriques est composée de batteries Li-ion. Cette thèse fait partie des thématiques communes de travail que mène L'ESTACA en collaboration avec le L2EP. L'objectif ce projet est d'étudier l'apport d'une source hybride composée de batteries Li-ion et des supercondensateurs, sur les performances d'un véhicule électrique urbain.Dans un premier temps, une stratégie de gestion d'energie basée sur l'approche des règles déterministes a été appliquée pour montrer l'intérêt de l'association des différentes technologies de batterie Li-ion (haute puissance, haute énergie) avec le supercondensateur en fonction de l'autonomie voulue. Cette étude nous a permis de proposer une solution optimale (poids, volume, coût..) composée d'une batterie énergétique et un supercondensateur.Dans la deuxième partie, on a suivie l'évolution du vieillissement des deux de deux batteries de type haute puissance et hautes énergie dans, respectivement, les configurations mono-source et hybride. Pour réaliser cette étude, un banc de tests, destiné au cyclage et la caractérisation des systèmes de stockage, a été utilisé. Les résultats obtenus, offriront la possibilité de se prononcer sur le type de batteries Li-ion qui pourrait être le plus intéressant pour l'alimentation des véhicules électriques

APA, Harvard, Vancouver, ISO, and other styles

2

Sadoun, Redha. "Intérêt d’une Source d’Energie Electrique Hybride pour véhicule électrique urbain – dimensionnement et tests de cyclage." Thesis, Ecole centrale de Lille, 2013. http://www.theses.fr/2013ECLI0009/document.

Full text

Abstract:

Actuellement, la principale source d’énergie embarquée dans les véhicules électriques est composée de batteries Li-ion. Cette thèse fait partie des thématiques communes de travail que mène L’ESTACA en collaboration avec le L2EP. L’objectif ce projet est d’étudier l’apport d’une source hybride composée de batteries Li-ion et des supercondensateurs, sur les performances d’un véhicule électrique urbain.Dans un premier temps, une stratégie de gestion d’energie basée sur l’approche des règles déterministes a été appliquée pour montrer l’intérêt de l’association des différentes technologies de batterie Li-ion (haute puissance, haute énergie) avec le supercondensateur en fonction de l’autonomie voulue. Cette étude nous a permis de proposer une solution optimale (poids, volume, coût..) composée d’une batterie énergétique et un supercondensateur.Dans la deuxième partie, on a suivie l’évolution du vieillissement des deux de deux batteries de type haute puissance et hautes énergie dans, respectivement, les configurations mono-source et hybride. Pour réaliser cette étude, un banc de tests, destiné au cyclage et la caractérisation des systèmes de stockage, a été utilisé. Les résultats obtenus, offriront la possibilité de se prononcer sur le type de batteries Li-ion qui pourrait être le plus intéressant pour l’alimentation des véhicules électriques Currently, the main embedded storage system supplying the electric vehicles is composed of Li-ion batteries. This thesis is one of the common themes of work that ESTACA leads in collaboration with L2EP. The objective of this work is to study the interest of a hybrid source composed of Li-ion batteries and supercapacitors to supply an urban electric.Firstly, an energy management strategy based on deterministic rules is developed to control the power between the battery and supercapacitor. To demonstrate the combination utility, different Li-ion battery technologies (Li-ion high power, high-Li-ion energy) are used on the sizing step. Through this study, we could propose an optimal solution (masses, volumes, costs...) consisting of battery and supercapacitor. In the second part, we have followed the evolution of capacity and the internal resistance losses of high power and high energy batteries type in, respectively, single-source and hybrid configurations. For this study, a test bench, developed for cycling and characterization of storage systems, was used. The results obtained provide the opportunity to choose Li-ion battery technology that could be the most interesting for the supply of electric vehicles

APA, Harvard, Vancouver, ISO, and other styles

3

Guigon, Camille. "Vieillissement par cyclage thermique de composites interlocks 3D à matrice polymère." Thesis, Chasseneuil-du-Poitou, Ecole nationale supérieure de mécanique et d'aérotechnique, 2015. http://www.theses.fr/2015ESMA0004.

Full text

Abstract:

L’introduction des composites dans des pièces structurelles critiques pour les aéronefs représente une réelle rupture technologique et nécessite des études spécifiques afin de maîtriser leur comportement et leur durabilité. Ce travail a pour objectifs de caractériser et de comprendre les mécanismes de vieillissement de composites interlock 3D à fibres de carbone et à matrice polymère lorsqu’ils sont soumis à des cycles thermiques.Dans ce but, un essai de cyclage thermique (-55°C/120°C), dont l’environnement thermique et gazeux est totalement maitrisé, a été mis en place pour le vieillissement d’échantillons composites représentatifs du motif interlock élémentaire. L’analyse des mécanismes de dégradation induits a été réalisée grâce i/ à la mise au point d’une méthode de caractérisation quantitative 3D de l’évolution des microfissures au cours du cyclage, basée sur des observations par microtomographie RX et sur le développement d’une procédure de traitement d’images spécifique, ii/ au développement d’un essai de cyclage thermique in situ synchrotron couplé à une technique de corrélation d’images volumiques 3D, et iii/ à des simulations par éléments finis prenant en compte l’architecture réelle des échantillons à l’échelle mésoscopique et le comportement thermo-viscoélastique de la matrice.Les résultats obtenus mettent en évidence des couplages thermo-chimio-mécaniques complexes,qui s’expriment à travers quatre paramètres influents : le temps (et le nombre de cycles),l’architecture de l’interlock, la ténacité de la matrice et sa sensibilité à la thermo-oxydation The introduction of composite materials in critical structural parts for aircrafts represents a real technological breakthrough and requires specific studies to understand their behavior and durability. This work aims to characterize and understand the ageing mechanisms incarbon/epoxy 3D interlock composites when they are submitted to thermal cycling.For this purpose, a thermal cycle test (-55°C/120°C), whose heat and gaseous environment istotally mastered, was set up for the ageing of composite samples of elemental interlock pattern dimensions. Analysis of induced degradation mechanisms was achieved by i/ the development ofa 3D quantitative characterization method of the evolution of microcracks during cycling, basedon observations by microtomography RX and the development of a specific image processing procedure, ii/ the development of an in situ thermal cycle test under synchrotron light, coupled to a digital volume correlation technique, and iii/finite elements simulations taking into account the actual mesoscopic architecture of the samples and the thermo-viscoelastic behavior of thematrix.The results reveal complex thermo-chemo-mechanical couplings that are linked to four important parameters: time (and the number of cycles), the interlock architecture, the matrix toughness andits sensitivity to thermo-oxidation

APA, Harvard, Vancouver, ISO, and other styles

4

Bandla, Venkat Nehru. "Modeling the internal inhomogeneous aging behavior in large-format commercial Li-ion batteries." Thesis, Amiens, 2018. http://www.theses.fr/2018AMIE0027/document.

Full text

Abstract:

Les batteries Li-ion (LIB) sont utilisées comme dispositifs de stockage d'énergie dans les applications automobiles, mobiles ou stationnaire. Cependant, leur vieillissement conduisant à une dégradation de leur performance reste un problème majeur. Les LIB présentent un comportement non uniforme qui entraîne une utilisation incomplète et un vieillissement non uniforme. L'objectif de ce travail est donc d'identifier les facteurs influençant le comportement inhomogène et d'étudier leur effet sur le vieillissement. Une approche combinée modèle/expérimentation est adoptée. Un dispositif expérimental a été développé pour simuler les dispersions thermiques et de potentiels dans les batteries Li-ion commerciales. Ce dispositif est utilisé pour effectuer des tests en cyclage et le vieillissement inhomogène est évalué par des tests de caractérisation effectués pendant et après le cyclage. Des modèles multi-physiques décrivant le comportement des LIB ont été développés pour représenter le comportement du système expérimental. Deux phénomènes de vieillissement identifiés expérimentalement sont pris en compte, à savoir la formation d'une couche de SEI (Solid Electrolyte Interface) et la perte de matière active d'électrode positive. Le premier est fortement dépendant de la température et le second est plus uniforme. Cette approche combinée a permis de montrer que la dispersion thermique avait plus d'impact que les différences de potentiel sur l'homogénéité du vieillissement Li-ion batteries (LIB) are used as energy storage devices in automobile, mobile and stationary applications. However their lifetime issue is a primary concern resulting in a decreased performance. Li-ion batteries exhibit non-uniform behavior that results in incomplete utilization of the cell energy and non-uniform aging. Thus the objective of this work is to identify the factors influencing the inhomogeneous behavior and to study their effect on aging. A combined modeling and experimental approach is adopted in this work. In the experimental work, a setup is developed that surrogates the thermal and potential gradients occurring in commercial LIB. This setup is used to perform long-term accelerated cycling tests and inhomogeneous aging behavior is assessed. Several characterization tests are performed during and after the completion of the cycling. In the modeling part, multiphysics models describing the electrochemical, electrical and thermal behavior of LIB are developed. These models are appropriately coupled integrated with an aging component to represent the experimental setup behavior. Two main degradation phenomena, namely SEI (Solid Electrolyte Interface) formation and positive electrode active material have been identified experimentally and modelled. The latter is uniform whereas the former is influenced by temperature. Based on this, thermal dispersion impact on the inhomogeneity is greater than potential dispersion

APA, Harvard, Vancouver, ISO, and other styles

5

Brissaud, Christine. "Etude morphologique et structurale des mécanismes de dégradation des batteries plomb/acide A recombinaison de gaz lors des tests de cyclage et de surchage." Lille 1, 1996. http://www.theses.fr/1996LIL10156.

Full text

Abstract:

Les batteries plomb/acide ont parfois une durée de vie plus courte que celle espérée. L'origine de ce phénomène, appelé perte de capacité prématurée, a été localisée à la plaque positive. Des essais de cyclage et de surcharge sur des batteries industrielles ont été menés dans le but d'identifier et de comprendre les mécanismes de dégradations qui sont responsables de la chute de capacité. Des analyses de la plaque positive, au cur de la matière active et à l'interface grille/matière active, ont été réalisés tout au long de la vie des batteries et ont permis de conclure quant aux mécanismes intervenant lors de la fin de vie. La chute de capacité des batteries lors du test de cyclage a été attribuée à la formation d'agrégats isolés de matière active positive. Les agglomérats isolés ne peuvent plus participer aux réactions électrochimiques de charge et de décharge. Ce phénomène a été modélisé à partir du mécanisme de frittage en considérant cependant un processus lié à la nature du test de cyclage. La corrosion intergranulaire généralisée de la grille positive entraîne la chute de capacité des batteries testées en surcharge. Cette corrosion implique une déformation importante de la grille et la matière active s'en détache alors progressivement. La grille ne peut plus jouer son rôle de collecteur - distributeur de courant

APA, Harvard, Vancouver, ISO, and other styles

6

Parrens, Coralie. "Cyclage thermomécanique d'un acier inoxydable austénitique à haute température : influence sur le vieillissement et le comportement mécanique. Caractérisations expérimentales et modélisations." Thesis, Toulouse, INPT, 2017. http://www.theses.fr/2017INPT0015/document.

Full text

Abstract:

Les aciers inoxydables austénitiques sont utilisés dans de nombreuses applications. L'alliage 310S possède des teneurs en chrome et en nickel particulièrement élevées qui lui confèrent une excellente résistance pour les utilisations à hautes températures. Néanmoins, pour des applications combinant cyclage thermique et chargement mécanique, la prédiction de la durée de vie des pièces est délicate. En effet, si de nombreuses données sont disponibles dans la littérature concernant le vieillissement et le fluage isotherme des aciers austénitiques, celles dédiées aux sollicitations couplées sont très rares et s’avèrent insuffisantes pour rendre compte des phénomènes macroscopiques observés industriellement. Une étude a donc été menée pour comprendre les mécanismes mis en jeu. Le vieillissement d’un acier 310S a été exploré pour plusieurs cycles thermiques à 870°C. Les microstructures obtenues ont été caractérisées par différents moyens expérimentaux. L’effet critique du cyclage thermique sur la germination et la croissance des précipités a été quantifié mettant en évidence une accélération de la germination de la phase sigma. D’autre part, des essais mécaniques à 20, 650, 780 et 870°C ont été réalisés sur une large plage de contraintes. Les résultats confirment la forte influence de la modification de la microstructure sur les propriétés élastiques et sur celles en fluage. L’augmentation conjointe du module d’Young, de la limite à rupture et des vitesses de fluage a été observée. La prédiction de la durée de vie de composants subissant des cyclages thermomécaniques doit donc tenir compte de l’évolution de la microstructure. Ces travaux aboutissent donc à une double modélisation qui permet, d’une part, de décrire la cinétique de transformation de phase et, d’autre part, de prédire les vitesses de fluage de l’acier 310S, en isotherme comme en cyclage thermomécanique, dans des conditions représentatives des conditions de service des pièces industrielles Austenitic stainless steels are widely used in industrial applications. 310S stainless steel has high chromium and nickel contents, providing a competitive mechanical behavior for high temperature utilizations. Nevertheless, lifetime prediction is difficult to assess under coupled mechanical and thermal solicitations. Many data are available on aging and isothermal creep of austenitic stainless steels, but few consider the coupled effect of multiple solicitations. These data are insufficient to explain industrial macroscopic observations. The aim of this study was thus to explore the involved mechanisms in such a case. 310S stainless steel aging was investigated under various thermal cycling solicitations at 870°C. The obtained microstructures were characterized by numerous experimental means. The effect of thermal cycling on nucleation and growth of sigma phase precipitates was quantified. The results of the present work revealed enhanced sigma phase nucleation in these non-isothermal conditions. In addition, mechanical tests were carried out at 20, 650, 780 and 870°C under a large range of stresses. The results highlight a noticeable influence of microstructural evolution on elastic and creep properties of this alloy. Simultaneous increases of Young modulus, rupture stress and creep rates were evidenced. It was thus evidenced that lifetime prediction of components under thermomechanical cycling must take into account the microstructure change during lifetime. Finally, two models were proposed in order to assess microstructural changes and creep behavior that apply to isothermal and thermomechanical cycling conditions mimicking in service conditions of industrial components

APA, Harvard, Vancouver, ISO, and other styles

7

Dbeiss, Mouhannad. "Mission Profile-Based Accelerated Ageing Tests of SiC MOSFET and Si IGBT Power Modules in DC/AC Photovoltaic Inverters." Thesis, Université Grenoble Alpes (ComUE), 2018. http://www.theses.fr/2018GREAT020/document.

Full text

Abstract:

Dans le cas des installations photovoltaïques, l’onduleur est le premier élément défaillant dont il est difficile d’anticiper la panne, et peu d’études ont été faites sur la fiabilité de ce type de convertisseur. L'objectif de cette thèse est de proposer des outils et méthodes en vue d'étudier le vieillissement des modules de puissance dans ce type d'application en se focalisant sur les phénomènes de dégradation liés à des aspects thermomécaniques. En règle générale, le vieillissement accéléré des modules de puissance est effectué dans des conditions aggravées de courant (Cyclage Actif) ou de température (Cyclage Passif) pour accélérer les processus de vieillissement. Malheureusement, en appliquant ce type de vieillissement accéléré, des mécanismes de défaillances qui ne se produisent pas dans la vraie application peuvent être observés et, inversement, d'autres mécanismes qui se produisent habituellement peuvent ne pas apparaître. La première partie de la thèse se focalise donc sur la mise en place d'une méthode de vieillissement accéléré des composants semi-conducteurs des onduleurs photovoltaïques. Cela est fait en s’appuyant sur l’analyse des profils de mission du courant efficace de sortie des onduleurs et de la température ambiante, extraits des centrales photovoltaïques situées au sud de la France sur plusieurs années. Ces profils sont utilisés pour étudier les dynamiques du courant photovoltaïque, et sont introduites dans des modèles numériques pour estimer les pertes et les variations de la température de jonction des semi-conducteurs utilisés dans les onduleurs, en utilisant l’algorithme de comptage de cycles "Rainflow". Cette méthode est ensuite mise en œuvre dans deux bancs expérimentaux. Dans le premier, les composants sous test sont des modules IGBT. Les composants sont mis en œuvre dans un banc de cyclage utilisant la méthode d'opposition et mettant en œuvre le profil de vieillissement défini précédemment. Un dispositif in-situ de suivi d'indicateurs de vieillissement (impédance thermique et résistance dynamique) est également proposé et évalué. Le deuxième banc est consacré à l'étude de modules de puissance à base de MOSFET SiC. Le vieillissement est effectué dans les mêmes conditions que pour les modules IGBT et de nombreux indicateurs électriques sont monitorés mais, cette fois ci, en extrayant les composants de l'onduleur de cyclage. Les résultats obtenus ont permis de déterminer des indicateurs de vieillissement d’IGBT et de MOSFET SiC utilisés dans un onduleur photovoltaïque In the case of photovoltaic installations, the DC/AC inverter has the highest failure rate, and the anticipation of its breakdowns is still difficult, while few studies have been done on the reliability of this type of inverter. The aim of this PhD is to propose tools and methods to study the ageing of power modules in this type of application, by focusing on ageing phenomena related to thermo-mechanical aspects. As a general rule, the accelerated ageing of power modules is carried out under aggravated conditions of current (Active Cycling) or temperature (Passive Cycling) in order to accelerate the ageing process. Unfortunately, when applying this type of accelerated ageing tests, some failure mechanisms that do not occur in the real application could be observed, while inversely, other mechanisms that usually occur could not be recreated. The first part of the PhD focuses on the implementation of an accelerated ageing method of the semiconductor devices inside photovoltaic inverters. This is accomplished by analyzing the mission profiles of the inverter’s output current and ambient temperature, extracted over several years from photovoltaic power plants located in the south of France. These profiles are used to study photovoltaic current dynamics, and are introduced into numerical models to estimate losses and junction temperature variations of semiconductors used in inverters, using the cycle counting algorithm “Rainflow”. This method is then performed in two experimental test benches. In the first one, the devices under test are IGBT modules, where the accelerated ageing profile designed is implemented using the opposition method. Moreover, an in-situ setup for monitoring ageing indicators (thermal impedance and dynamic resistance) is also proposed and evaluated. The second bench is devoted to study the ageing of SiC MOSFET power modules. The accelerated ageing test is carried out under the same conditions as for the IGBT modules with more monitored electrical indicators, but this time by disconnecting the semiconductor devices from the inverter. The results obtained allowed to determine several potential ageing indicators of IGBTs and SiC MOSFETs used in a photovoltaic inverter

APA, Harvard, Vancouver, ISO, and other styles

8

Larignon, Céline. "Mécanismes d'endommagement par corrosion et vieillissement microstructural d'éléments de structure d'aéronef en alliage d'aluminium 2024-T351." Phd thesis, Toulouse, INPT, 2011. http://oatao.univ-toulouse.fr/6994/1/larignon_partie_1_sur_2.pdf.

Full text

Abstract:

Cette thèse s'inscrit dans le cadre d'une collaboration avec EADS Innovation Works et AIRBUS. L'objectif des travaux est d'identifier les modes d'endommagements possibles d'éléments de structure métalliques d'aéronefs développés en service et d'en comprendre les mécanismes et les effets sur les propriétés des matériaux afin de contribuer au développement d'une méthode de contrôle non destructif innovante. Le matériau sélectionné est un alliage d'aluminium 2024-T351, l'un des matériaux constitutifs de la voilure et du fuselage d'avions civils. Les modes d'endommagement étudiés sont la corrosion et le vieillissement microstructural. La première partie de ces travaux est consacrée à l'analyse de l'influence des conditions d'exposition au milieu corrosif sur le développement de la corrosion intergranulaire et à l'identification des mécanismes de dégradation associés et de leurs cinétiques. Des conditions d'exposition originales alternant des phases d'immersion et d'émersion à différentes températures ont été explorées dans la mesure où elles semblent particulièrement représentatives des conditions d'exposition réelles. Les mécanismes proposés pour comprendre l'endommagement observé dans certaines de ces conditions d'exposition au milieu corrosif, impliquent un phénomène apparenté à de la fragilisation par l'hydrogène, phénomène qui n'est, à l'heure actuelle, pas encore reconnu pour les alliages d'aluminium de la série 2xxx. L'influence de l'hydrogène sur les propriétés physico-chimiques et mécaniques du matériau est donc étudiée dans la seconde partie de ces travaux. Enfin, l'influence d'un vieillissement microstructural sur les propriétés de l'alliage ainsi que les couplages possibles entre vieillissement microstructural et phénomènes de corrosion sont abordés dans une dernière partie. L'ensemble des résultats obtenus permet de révéler des pistes pour développer une méthode CND innovante permettant la caractérisation physique in-situ du niveau d'endommagement à l'échelle locale d'éléments de structures en alliages d'aluminium.

APA, Harvard, Vancouver, ISO, and other styles

9

Farrell, Jeanne. "The molecular identity of soluble adenylyl cyclase /." Access full-text from WCMC, 2008. http://proquest.umi.com/pqdweb?did=1528353801&sid=2&Fmt=2&clientId=8424&RQT=309&VName=PQD.

Full text

APA, Harvard, Vancouver, ISO, and other styles

10

Meless, Dejen. "Test Cycle Optimization using Regression Analysis." Thesis, Linköping University, Automatic Control, 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-54809.

Full text

Abstract:

Industrial robots make up an important part in today’s industry and are assigned to a range of different tasks. Needless to say, businesses need to rely on their machine park to function as planned, avoiding stops in production due to machine failures. This is where fault detection methods play a very important part. In this thesis a specific fault detection method based on signal analysis will be considered. When testing a robot for fault(s), a specific test cycle (trajectory) is executed in order to be able to compare test data from different test occasions. Furthermore, different test cycles yield different measurements to analyse, which may affect the performance of the analysis. The question posed is: Can we find an optimal test cycle so that the fault is best revealed in the test data? The goal of this thesis is to, using regression analysis, investigate how the presently executed test cycle in a specific diagnosis method relates to the faults that are monitored (in this case a so called friction fault) and decide if a different one should be recommended. The data also includes representations of two disturbances.The results from the regression show that the variation in the test quantities utilised in the diagnosis method are not explained by neither the friction fault or the test cycle. It showed that the disturbances had too large effect on the test quantities. This made it impossible to recommend a different (optimal) test cycle based on the analysis.

APA, Harvard, Vancouver, ISO, and other styles

11

Sweeney, Claire. "Cell cycle regulators in the murine testis." Thesis, University of Cambridge, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.364276.

Full text

APA, Harvard, Vancouver, ISO, and other styles

12

Murphy, Martin P. "Components of MPF in the murine testis." Thesis, University of Cambridge, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.336742.

Full text

APA, Harvard, Vancouver, ISO, and other styles

13

Woodfield, Robert Leon. "The relationship between oestradiol status and performance on tests of visuo-spatial ability." Thesis, King's College London (University of London), 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.245421.

Full text

APA, Harvard, Vancouver, ISO, and other styles

14

Tola, Tola Adrian Patricio. "Analytical and Experimental Investigation of Low-Cycle Fatigue Fracture in Structural Steel." Diss., Virginia Tech, 2020. http://hdl.handle.net/10919/100051.

Full text

Abstract:

The mechanism of metal material failure due to inelastic cyclic deformations is commonly described as Low-Cycle Fatigue (LCF). Fracture in steel structures caused by earthquakes can be associated with this mechanism. Mathematical expressions describing the material deterioration due to LCF are often referred to as LCF laws. The accurate determination of the safety of steel structures against earthquake-induced failure requires the use of LCF laws which have been sufficiently validated with experimental test data. The present study combined experimental testing and computational simulation to enhance the understanding of structural steel fracture due to LCF. The experiments were conducted in specimens extracted from the flat and corner regions of two rectangular steel hollow sections with different thickness. A total of 60 cylindrical specimens with a circumferential notch were subjected to different combinations of axial and torsional loading. The loading protocols and notch geometry were designed to produce different stress states at the location of fracture initiation. Finite element analyses were conducted to obtain the stress state and inelastic strains at the fracture initiation location. This information was then used for the calibration of five existing LCF laws. The calibration also allowed the comparative evaluation of the capability of the different laws to capture fracture initiation for different stress states, with a single set of values for the various parameters. The accuracy of the calibrated LCF laws to predict fracture initiation in a large-scale test was also investigated. To this end, a test was conducted on a rectangular steel tube subjected to cyclic axial loading. A finite element analysis of this test was conducted, and predictions of the instant and location of fracture initiation using the calibrated LCF laws were compared with the experimental observations. Doctor of Philosophy The mechanism of material failure due to repeated cycles of large deformations is denoted as Low-Cycle Fatigue (LCF); this failure mechanism can occur in steel structures subjected to loading conditions such as those induced by earthquakes. Mathematical expressions that evaluate the material deterioration due to LCF are often used to predict the instant and location of fracture initiation in small-scale and large-scale tests. An experimental program was conducted for the study of fracture associated with LCF. A total of 60 specimens were fabricated with material extracted from the flat and corner regions of two rectangular steel tubes; the applied loads elongated and/or twisted the specimens until they ruptured. Computational simulations of these tests were conducted to obtain key information at the location of the observed fracture initiation. This information was used to adjust five mathematical expressions suggested by previous researchers that could predict the same instant of fracture initiation observed in the experiments. The accuracy of the predictions from each of these mathematical expressions was evaluated. The accuracy of these mathematical expressions to predict fracture initiation in a large-scale test was also investigated. To this end, an experiment was conducted on a rectangular steel tube subjected to repeated cycles of deformation. A computational simulation of this test was also developed, and predictions of the instant and location of fracture initiation were compared with the experimental observations.

APA, Harvard, Vancouver, ISO, and other styles

15

Kunapareddy, Naveen. "A Proof-of-Concept Test for Seperation Efficiency of an Electro-Cyclone." Ohio University / OhioLINK, 2009. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1237569168.

Full text

APA, Harvard, Vancouver, ISO, and other styles

16

Lamberts, Robert Patrick. "The development of an evidenced-based submaximal cycle test designed to monitor and predict cycling performance : the Lamberts and Lambert submaximal cycle test (LSCT)." Doctoral thesis, University of Cape Town, 2009. http://hdl.handle.net/11427/2757.

Full text

Abstract:

Includes abstract. Includes bibliographical references. The HIMS test, which consists of controlled exercise at increasing workloads, has been developed to monitor changes in training status and accumulative fatigue in athletes. As the workload can influence the day-to-day variation in heart rate, the exercise intensity which is associated with the highest sensitivity needs to be established with the goal of refining the interpretability of these heart rate measurements. The aim of the study was to determine the within subject day-to-day variation of submaximal and recovery heart rate in subjects who reached different exercise intensities.

APA, Harvard, Vancouver, ISO, and other styles

17

Christie, Karen Louise. "Development of a predictive cycle ergometer test providing individualized results." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp04/mq23784.pdf.

Full text

APA, Harvard, Vancouver, ISO, and other styles

18

Baker, Julien Steven. "Optimisation considerations for the measurement of human muscle power." Thesis, University of South Wales, 2000. https://pure.southwales.ac.uk/en/studentthesis/optimisation-considerations-for-the-measurement-of-human-muscle-power(6dd8a26f-b3d9-47c4-8511-90bd35f18ac3).html.

Full text

Abstract:

High intensity cycle ergometer exercise tests are designed to measure power outputs. Most of the tests utilise resistive forces that are based on total-body mass values (TBM). Conceptually, selecting an optimal resistive force based on total-body mass may not be the best approach. Resistive forces that reflect the mass of the lean tissue specifically involved in the performance of the diagnostic task may be more appropriate. To investigate this theory the following studies were proposed. STUDY ONE. To identify the upper body contribution to a cycle ergometer test via the handgrip. STUDY TWO. To examine any differences in power profiles, when loading procedures were based on total-body mass (TBM) or fat-free mass (FFM). STUDY THREE. To investigate the sympathoadrenergic and blood lactate responses, when loading procedures were based on total-bodymass (TBM) or fat-free mass (FFM).STUDY FOUR. To measure blood concentrations of, lipidhydroperoxides (LH), malondialdehyde (MDA), creatine kinase (CK)and myoglobin (Mb) that may occur when resistive forces were based on total-body mass (TBM) or fat-free mass (FFM). STUDY ONEIndices of mechanical power output were obtained from twelve subjects during high intensity leg cycle ergometry tests (20 second duration; 75 grams per kilogram total-body mass) using two protocols:one with a standard handle-bar grip (with - grip), and one with supinated wrists (without - grip). Peak mechanical power, mean mechanical power, fatigue index and total mechanical work values were calculated for each subject during each test, and the sample mean differences associated with the two protocols were compared using paired Student t-tests. The with-grip protocol yielded significantly greater peak mechanical power output and greater fatigue index than the without - grip protocol(886 ± 124 W vs 815 ± 151 W, respectively; and 35 ± 10% vs 25 ±8%, respectively ; P < 0.05}. The electrical activity of the anterior forearm musculature was measured in the twelfth subject during the performance of each of the test protocol in an initial attempt to quantify any differences in muscular activity between protocols. While peak mechanical power output was greater during the with - grip protocol,than during the without - grip protocol, the electromyographs showed much greater forearm muscle activity during the with - grip protocol. Thus the protocol which allowed for the greatest measure of peak leg power output was also associated with considerable arm muscle activity. These findings should be considered when blood samples are taken from the arm for the biochemical analysis of cycling tasks. STUDY TWOStudy two compared the maximal exercise performance of 10 men during friction braked cycle ergometry of 20 s duration when resistive forces reflected total-body mass (TBM) or fat-free mass (FFM). Fat mass was calculated from the sum of skinfold thicknesses. Increases(P < 0.05) in peak power output (PPO) were found between TBM and FFM (1015 ± 165 W TBM vs 1099 ± 172 W FFM). Decreases (P <0.05) were observed for the time taken to reach PPO (3.8 ± 1.4 s TBMvs 2.9 ± 1 s FFM). Pedal velocity increased (P < 0.05) during the FFM protocol (129.4 ± 8.2 rpm TBM vs 136.3 ± SrpmFFM). Rating of perceived exertion (RPE) was also (P < 0.05) greater for FFM (18.4 ± 1.6 TBM vs 19.8 ± 0.4 FFM). No changes were found for Mean Power Output (MPO), fatigue index (FI) or Work Done(WD) between trials. These findings suggest that high intensity resistive force loading protocols may need to be reconsidered. Results from this study indicate that the active tissue component of body composition needs consideration in resistive force selection when ascertaining maximal cycle ergometer power profiles. STUDY THREEThe purpose of study three was to compare the sympathoadrenergic and blood lactate responses to maximal exercise performance during 30s cycle ergometry when resistive forces were dependent on total-bodymass (TBM) and fat-free mass (FFM). Correlations (P < 0.05) were recorded between PPOs, and immediate post-exercise noradrenaline concentrations for both the TBM and FFM protocols. Increases (P < 0.05) in the concentrations of adrenaline, noradrenaline and lactate from rest to immediately post exercise were observed for both the TBM and FFM protocols, with decreases in concentration noted (P < 0.05) immediately post to 24 h post exercise (see table 6.3). There were no differences (P > 0.05) recorded between TBM and FFM during any of the blood sampling stages. These results are interesting when we consider that with increases in PPO recorded for the FFM protocol there were no differences between protocols in the estimation of neurophysiological and metabolic stress as determined by plasmaadrenaline, noradrenaline and blood lactate concentrations. STUDY FOUR. Study four compared power outputs, and blood levels of, lipidhydroperoxides (LH), malondialdehyde (MDA), creatine kinase (CK), myoglobin (Mb) and lactate ([La-]g) following 30 s of maximal cycleergometry exercise when resistive forces were dependent on total-bodymass (TBM) or fat-free mass (FFM). Alpha-tocopherol, Retinol and uric acid concentrations were also measured to quantify the activity of selected antioxidants. Cardiac troponin concentrations (cTnl) were also determined to exclude protein leakage from the myocardium. Increases in CK activity was recorded from rest to immediately post exercise during both the TBM and FFM protocols (P < 0.05 ; P < 0.05 respectively) and decreased from immediately post to 24 h post exercise during the FFM protocol only. LH increased from rest to immediately post exercise for both the TBM and FFM protocol (P < 0.05 ; P < 0.05 respectively) and decreased 24 h post exercise for both protocols. Differences in LH concentrations were also observed immediately post exercise between the TBM and FFM protocols (P < 0.05). Increases in MDA concentrations were recorded from rest to immediately post exercise for TBM (P < 0.05), with a decrease recorded from immediate post to 24 h post exercise. Differences in MDA concentrations were recorded between the TBM and FFM protocol immediately post exercise. Differences in TBM and FFM concentrations were also recorded immediately post exercise for Mb (P < 0.05). Blood lactate values([La~]B) increased (P < 0.05) from rest, to immediately post exercise,and returned to resting values 24 h post exercise for both the TBM and FFM. Alpha-tocopherol and uric acid concentrations decreased from rest to immediately post exercise for both TBM and FFM protocols (P < 0.05 ; P < 0.05 respectively) and increased 24 h post exercise. There were no changes observed in Retinol concentrations for any of the blood sampling stages. The results of the study suggest that greater power outputs are obtainable with significantly less muscle damage and oxidative stress when resistive forces reflect FFM mass during loading procedures. This finding may also be related to better force velocity relationships observed for the FFM protocol, ie more efficient mechanics of movement which may result in less strain, and therefore less internal damage. Findings from the study indicate that procedures that produce greater power values, with no difference in stress response, that are less damaging to muscle tissue and relate to the active tissue during this type of exercise, may need to be explored in preference to loading procedures that include both lean and fat masses.

APA, Harvard, Vancouver, ISO, and other styles

19

Wilson, Kier R. "Validation of an intermittent sprint cycle test for female hockey players." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape8/PQDD_0017/MQ47115.pdf.

Full text

APA, Harvard, Vancouver, ISO, and other styles

20

Seidt, Jeremy Daniel. "Development of a novel vibration based high cycle fatigue test method." Connect to resource, 2001. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1209585565.

Full text

APA, Harvard, Vancouver, ISO, and other styles

21

Zhang, Yuanci. "Performance and ageing quantification of electrochemical energy storage elements for aeronautical usage." Thesis, Bordeaux, 2019. http://www.theses.fr/2019BORD0029/document.

Full text

Abstract:

Dans un contexte de progression du stockage d’énergie sous forme électrochimique dans les transports, notamment dans l’aéronautique, les problématiques de performance, de fiabilité, de sureté de fonctionnement et de durée de vie du stockeur sont essentielles pour utilisateurs. Cette thèse se focalise ces voltes pour l’avion plus électrique. Les technologies étudiées correspondent à des éléments commerciaux de dernière génération de type Lithium-ion (NMC/graphite+SiO, NCA/graphite, LFP/graphite, NMC/LTO), Lithium-Soufre (Li-S), supercondensateur et hybride (LiC). Une première partie de ce manuscrit s’attache à la quantification des performances des différents éléments dans l’environnement aéronautique [-20°C, 55°C] et pour l’usage aéronautique. Un modèle comportemental de type électro-thermique est développé et validé. La seconde partie est consacrée à la quantification du vieillissement des différents éléments. Les résultats de vieillissement calendaire et en cyclage actif sont présentés ainsi que ceux des tests abusifs. Une méthode d’estimation de l’état de santé (SOH) des éléments basés sur l’analyse de la capacité incrémentale (ICA) est proposée. Enfin, l’évaluation de la robustesse des éléments de stockage lors de tests de vieillissement accéléré avec un profil spécifique à l’usage aéronautique est proposé. Les modèles de vieillissement et la méthode d'estimation de SOH proposés précédemment sont utilisés ici pour évaluer l'impact de la température sur la vitesse de dégradation et pour estimer le SOH des cellules vieillies à l’aide de ce profil aéronautique In the context of progress in the electrochemical energy storage systems in the transport field, especially in the aeronautics, the issues of performance, reliability, safety and robustness of these elements are essential for users. This thesis is focused on these issues for the more electric aircraft. The technologies studied correspond to the latest generation commercial elements of Lithium-ion batteries (NMC/ graphite + SiO, NCA/graphite, LFP/graphite, NMC/LTO), Lithium-Sulfur (Li-S), Supercapacitor and Lithium-ion capacitors. The first part of this manuscript is dedicated to the performance quantification of the different electrochemical energy storage elements in aeronautical environment [-20°C, 55°C] and usage. An efficient and accurate electro-thermal model is developed and validated. The second part is devoted to the calendar and power cycling ageings as well as to the presentation of abuse testing results. A State Of Health (SOH) estimation based on incremental capacity analysis method is proposed. Finally, the robustness of the storage elements during accelerated ageing tests with a specific profile for the aeronautical usage is evaluated. The ageing models and SOH estimation methods proposed in the previous sections are used here to evaluate the impact of temperature on the degradation rate and to estimate the SOH of the cells with this aeronautical profile

APA, Harvard, Vancouver, ISO, and other styles

22

Regainia, Loukmen. "Assistance au développement et au test d'applications sécurisées." Thesis, Université Clermont Auvergne‎ (2017-2020), 2018. http://www.theses.fr/2018CLFAC018/document.

Full text

Abstract:

Garantir la sécurité d’une application tout au long de son cycle de vie est une tâche fastidieuse. Le choix, l’implémentation et l’évaluation des solutions de sécurité est difficile et sujette a des erreurs. Les compétences en sécurité ne sont pas répondues dans toutes les équipes de développement. Afin de réduire ce manque de compétences en sécurité, les développeurs ont a leurs disposition une multitude de documents décrivant des problèmes de sécurité et des solutions requises (i.e., vulnérabilités, attaques, principes de sécurité, patrons sécurité, etc.). Abstraites et informelles, ces documents sont fournis par des sources différentes et leur nombre est en constante croissance. Les développeurs sont noyés dans une multitude de documents ce qui fait obstruction à leur capacité à choisir, implémenter et évaluer la sécurité d’une application. Cette thèse aborde ces questions et propose un ensemble de méthodes pour aider les développeurs à choisir, implémenter et évaluer les solutions de sécurité face aux problèmes de sécurité. Ces problèmes sont matérialisés par les failles, les vulnérabilités, les attaques, etc. et les solutions fournies par des patrons de sécurité. Cette thèse introduit en premier une méthode pour aider les développeurs dans l’implémentation de patrons de sécurité et l’estimation de leur efficacité face aux vulnérabilités. Puis elle présente trois méthodes associant les patrons de sécurité, les vulnérabilités, les attaques, etc. au sein d’une base de connaissance. Cette dernière permet une extraction automatique de classifications de patrons et améliore la rapidité et la précision des développeurs dans le choix des patrons de sécurité face à une vulnérabilité ou une attaque. En utilisant la base de connaissance, nous présentons une méthode pour aider les développeurs dans la modélisation des menaces ainsi que la générations et l’exécution des cas de test de sécurité. La méthode est évaluée et les résultats montrent que la méthode améliore l’efficacité, la compréhensibilité et la précision des développeurs dans le choix des patrons de sécurité et d’écriture des cas de test de sécurité Ensuring the security of an application through its life cycle is a tedious task. The choice, the implementation and the evaluation of security solutions is difficult and error prone. Security skills are not common in development teams. To overcome the lack of security skills, developers and designers are provided with a plethora of documents about security problems and solutions (i.e, vulnerabilities, attacks, security principles, security patterns, etc.). Abstract and informal, these documents are provided by different sources, and their number is constantly growing. Developers are drown in a sea of documentation, which inhibits their capacity to design, implement, and the evaluate the overall application security. This thesis tackles these issues and presents a set of approaches to help designers in the choice, the implementation and the evaluation of security solutions required to overcome security problems. The problems are materialized by weaknesses, vulnerabilities, attacks, etc. and security solutions are given by security patterns.This thesis first introduces a method to guide designers implement security patterns and assess their effectiveness against vulnerabilities. Then, we present three methods associating security patterns, attacks, weaknesses, etc. in a knowledge base. This allows automated extraction of classifications and help designers quickly and accurately select security patterns required to cure a weakness or to overcome an attack. Based on this nowledge base, we detaila method to help designers in threat modeling and security test generation and execution. The method is evaluated and results show that the method enhances the comprehensibility and the accuracy of developers in the security solutions choice, threat modeling and in the writing of security test cases

APA, Harvard, Vancouver, ISO, and other styles

23

Hauser, Richard P. "The firm “life-cycle” hypothesis and dividend policy: Tests on propensity to pay, dividend initiation, and dividend growth rates." Kent State University / OhioLINK, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=kent1342289582.

Full text

APA, Harvard, Vancouver, ISO, and other styles

24

Moreno, Oscar Ray. "Investigation and development of oil-injection nozzles for high-cycle fatigue rotor spin test." Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 2005. http://library.nps.navy.mil/uhtbin/hyperion/05Mar%5FMoreno.pdf.

Full text

Abstract:

Thesis (M.S. in Mechanical Engineering)--Naval Postgraduate School, March 2005. Thesis Advisor(s): Raymond Shreeve, Garth Hobson. Includes bibliographical references (p. 91-93). Also available online.

APA, Harvard, Vancouver, ISO, and other styles

25

Kasarabada, Yasaswy. "A Verilog Description and Efficient Hardware Implementation of the Baillie-PSW Primality Test." University of Cincinnati / OhioLINK, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1471347471.

Full text

APA, Harvard, Vancouver, ISO, and other styles

26

Vennerberg, Patrik. "Improvement of Routine Test Process of High Voltage Power Capacitors." Thesis, Högskolan Dalarna, Maskinteknik, 2009. http://urn.kb.se/resolve?urn=urn:nbn:se:du-4097.

Full text

Abstract:

The capacitor test process at ABB Capacitors in Ludvika must be improved to meet future demands for high voltage products. To find a solution to how to improve the test process, an investigation was performed to establish which parts of the process are used and how they operate. Several parts which can improves the process were identified. One of them was selected to be improved in correlation with the subject, mechanical engineering. Four concepts were generated and decision matrixes were used to systematically select the best concept. By improving the process several benefits has been added to the process. More units are able to be tested and lead time is reduced. As the lead time is reduced the cost for each unit is reduced, workers will work less hours for the same amount of tested units, future work to further improve the process is also identified. The selected concept was concept 1, the sway stop concept. This concept is used to reduce the sway of the capacitors as they have entered the test facility, the box. By improving this part of the test process a time saving of 20 seconds per unit can be achieved, equivalent to 7% time reduction. This can be compared to an additional 1400 units each year.

APA, Harvard, Vancouver, ISO, and other styles

27

Araújo, Larissa Barreto de. "Inferência estatística sobre a qualidade do processo de compras públicas diretas em uma Instituição de ensino." Universidade Federal do Amazonas, 2013. http://tede.ufam.edu.br/handle/tede/3843.

Full text

Abstract:

Made available in DSpace on 2015-04-23T12:43:05Z (GMT). No. of bitstreams: 1 larissa.pdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Previous issue date: 2013-07-23 Alavancado pelo processo da globalização, a qualidade tornou-se função decisiva para a conquista de clientes e competitividade. Assim, as organizações estão evoluindo para o aperfeiçoamento de seus métodos de gestão, com intuito de atender aos requisitos exigidos pelos clientes. Dentro do contexto da gestão da qualidade, um dos métodos mais difundidos é o Ciclo PDCA, que pode ser desdobrado dentro de cada processo da organização e para o sistema de processos em sua totalidade. No setor de serviços, a percepção do cliente é indispensável para alteração de diretriz de controle (melhorias). Para isto, a estatística pode ser utilizada para viabilizar a coleta, o processamento e a disposição das informações, de forma que o conhecimento gerado é utilizado, por meio do Ciclo PDCA, para atingir metas de melhoria. Neste sentido, o trabalho objetiva propor um modelo de inferência estatística sobre a qualidade do processo de compra pública direta em Instituição de Ensino. Para isso, foi analisada a rotina do setor de compras, na qual se fez o uso das ferramentas da qualidade e dos testes não paramétricos para fazer comparações entre grupos de fatores. Com isso, foi possível identificar os fatores que influenciam de forma significativa o aumento do tempo dos processos. A abordagem da pesquisa é qualitativa, principalmente na coleta e análise dos dados, e quantitativa no tratamento. Quanto aos fins, a natureza da pesquisa é exploratória e descritiva e quanto aos meios de investigação, um estudo de caso. Com base no marco teórico, foi possível elaborar um modelo de procedimentos para execução de uma experimentação que envolve o Ciclo PDCA, as ferramentas da qualidade e os testes não paramétricos para inferência estatística sobre a qualidade do processo. A partir da aplicação deste modelo, identificou-se que o fator valor alto é o mais significativo no processo de compra pública direta. Fora este fator, a natureza do processo classificada como material permanente e processos que tramitam por mais de dezesseis setores também são fatores que influenciam no aumento do tempo. Dessa forma, foi possível contribuir com a área de gestão da qualidade, visto que se delineou a respeito da inferência estatística na qualidade em processos de compras, um assunto pouco difundido no âmbito do setor público.

APA, Harvard, Vancouver, ISO, and other styles

28

Oliveira, Henrique Barcellos de. "Modelos análiticos para o desenvolvimento de alvos metálicos de alta performance irradiados nos ciclotrons Cyclone 30 e Cyclone 18 do IPEN-CNEN/SP." Universidade de São Paulo, 2009. http://www.teses.usp.br/teses/disponiveis/85/85131/tde-22092011-095307/.

Full text

Abstract:

Foram desenvolvidos modelos analíticos que descrevem os elementos básicos para irradiações de alvos metálicos em ciclotrons. Parâmetros importantes como valor máximo de corrente de feixe e potência térmica depositada sobre o alvo foram obtidos e confrontados com situações práticas. De forma totalmente inédita, foram determinados analiticamente as características encontradas em situações de intensos transientes térmicos, quando altas concentrações de prótons em uma pequena região do feixe provocam intensos gradientes de temperatura em pequenas regiões do alvo. A comparação dos resultados obtidos com aqueles encontrados na literatura mostraram que os modelos desenvolvidos são satisfatórios, tendo em vista todas as limitações do modelo proposto. Analytical models were developed that describe the basic elements for metal targets irradiation in cyclotrons. Important parameters such as maximum beam current value and thermal power deposited on target were obtained and compared with practical situations. In an unprecedented way, were determined analytically the features found in intense thermal transient situations, when high protons concentrations in a small region of the beam cause intense temperature gradients in small regions of the target. Comparing with results found in the literature showed that the developed models are satisfactory, in view of all limitations of the proposed model.

APA, Harvard, Vancouver, ISO, and other styles

29

Silva, Carolina Ribeiro e. "Genética toxicológica da chalcona sulfonamida (CPN): evidências de genoto-xicidade e antimutagenicidade em diferentes sistemas-teste in vivo e in vitro." Universidade Federal de Goiás, 2015. http://repositorio.bc.ufg.br/tede/handle/tede/5596.

Full text

Abstract:

Submitted by Cláudia Bueno (claudiamoura18@gmail.com) on 2016-05-19T21:30:50Z No. of bitstreams: 2 Tese - Carolina Ribeiro e Silva - 2015.pdf: 2710382 bytes, checksum: 03a38ab42eb321f4a7528fa33c9b8110 (MD5) license_rdf: 23148 bytes, checksum: 9da0b6dfac957114c6a7714714b86306 (MD5) Approved for entry into archive by Luciana Ferreira (lucgeral@gmail.com) on 2016-05-20T14:07:56Z (GMT) No. of bitstreams: 2 Tese - Carolina Ribeiro e Silva - 2015.pdf: 2710382 bytes, checksum: 03a38ab42eb321f4a7528fa33c9b8110 (MD5) license_rdf: 23148 bytes, checksum: 9da0b6dfac957114c6a7714714b86306 (MD5) Made available in DSpace on 2016-05-20T14:07:56Z (GMT). No. of bitstreams: 2 Tese - Carolina Ribeiro e Silva - 2015.pdf: 2710382 bytes, checksum: 03a38ab42eb321f4a7528fa33c9b8110 (MD5) license_rdf: 23148 bytes, checksum: 9da0b6dfac957114c6a7714714b86306 (MD5) Previous issue date: 2015-03-20 Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES Sulfonamide chalcone derivatives have shown important biological applications, including antitumor activity. In the present study, we investigated the biological effects of the sulfonamide chalcone N-{4-[3-(4-nitrophenyl)prop-2-enoyl]phenyl} benzenesulfonamide (CPN) through bioindicators of genetic damage in bacteria, animal and human. In the Ames Mutagenicity Test, CPN did not significantly increase the number of His+ revertants in Salmonella typhimurium tester strains TA98 and TA100 at all doses tested (p > 0.05). However, CPN presented a moderate mutagenic and toxic profile, due to dose-response relationship observed at all doses tested for TA98 and TA100 strains. In the antimutagenic evaluation of Ames Test, CPN presented antimutagenic activity at all doses tested in TA98 strain (p < 0.05). In the TA100 strain, CPN showed antimutagenic activity in doses over 50 μg/plate. In the Micronucleus Test, the results demonstrated that CPN increased the frequency of micronucleated polychromatic erythrocytes (MNPCE) at 24 h and 48 h, at all doses tested, demonstrating mutagenic effect of this compound. A decrease in polychromatic/normochromatic erythrocyte ratio (PCE/NCE) was observed at 24 h and 48 h, indicating the cytotoxic action of CPN. CPN co-administered with mitomycin C (MMC) significantly decreased the frequency of MNPCE at all doses tested in 24 h, demonstrating antimutagenic action (p < 0.05). Also, there was a decrease in the frequency of MNPCE at all tested doses in 48 h, but this decrease was not significant (p > 0.05). Additionally, CPN co-administered with MMC increased PCE/NCE ratio at all doses tested, in both times, demonstrating its anticytotoxic effect. In the Comet Assay, CPN significantly increased the percentage of DNA damages at all doses tested (p < 0.05), demonstrating genotoxic activity. In the analysis of cell cycle kinetics, CPN did not induce significant changes in the cell cycle phases G0/G1, S and G2/M of peripheral blood mononuclear cells (PBMC) (p > 0.05). However, doses of 256 and 512 μmol/L of the CPN presented a significant increase in the percentage of cells in sub-G1 (p < 0.05), which is indicative of apoptosis, indicating cytotoxic action. For apoptosis and necrosis detection using Annexin V/Propidium Iodide stain, CPN showed a cytotoxic effect by inducing late apoptosis and necrosis. Thus, according to tests performed CPN presented genotoxic, cytotoxic, antigenotoxic, and anticytotoxic activities. Derivados de chalcona sulfonamida tem apresentado importantes atividades biológicas, incluindo atividade antitumoral. No presente estudo, investigou-se os efeitos biológicos da chalcona sulfonamida N-{4-[3-(4-nitrofenil)prop-2-enoil]fenil}-benzenosulfonamida (CPN) mediante a análise de bioindicadores de danos genéticos em sistemas-teste bacteriano, animal e humano. No Teste de Mutagenicidade de Ames, CPN não aumentou significativamente o número de revertentes prototróficas de Salmonella typhimurium, em nenhuma das cepas testadas, TA98 e TA100, em nenhuma das doses (p > 0,05). Entretanto, CPN apresentou um perfil moderado de um composto mutagênico e tóxico, devido à relação dose-resposta observada em todas as doses testadas, para as cepas TA98 e TA100. Na avaliação antimutagênica do Teste de Ames, CPN apresentou atividade antimutagênica para todas as doses testadas na cepa TA98 (p < 0,05). Na cepa TA100, CPN mostrou atividade antimutagênica nas doses acima de 50 μg/placa (p < 0,05). Os resultados do Teste do Micronúcleo demonstraram que CPN aumentou a frequência de eritrócitos policromáticos micronucleados (EPCMN) no tempo de 24 e 48 h, em todas as doses testadas, demonstrando efeito mutagênico deste composto. Uma diminuição na razão de eritrócitos policromáticos/normocromáticos (EPC/ENC) foi observada no tempo de 24 e 48 h, indicando ação citotóxica de CPN. CPN co-administrado com mitomicina C (MMC) diminuiu significativamente a freqüência de EPCMN em todas as doses testadas no tempo de 24 h, demonstrando ação antimutagênica (p < 0,05). Houve também uma diminuição na frequência de EPCMN em todas as doses testadas, no tempo de 48 h, mas a diminuição não foi significativa (p > 0,05). Além disso, CPN co-administrado com MMC aumentou a razão de EPC/ENC em todas as doses testadas, nos tempos de 24 e 48 h, demonstrando efeito anticitotóxico. No Ensaio Cometa, CPN aumentou significativamente a porcentagem de danos no DNA em todas as doses testadas (p < 0,05), demonstrando atividade genotóxica. Na análise da Cinética do Ciclo Celular, CPN não induziu alteração significativa nas fases G0/G1, S e G2/M do ciclo celular de células mononucleares do sangue periférico (PBMC) (p > 0,05). Entretanto, as doses de 256 e 512 μmol/L de CPN apresentaram um aumento significativo na porcentagem de células em sub-G1 (p < 0,05), o qual é um indicativo de apoptose, demonstrando ação citotóxica. Na detecção de apoptose e necrose por coloração com Anexina V/Iodeto de Propídeo, CPN mostrou um efeito citotóxico, pela indução de apoptose tardia e necrose. Assim, de acordo com os ensaios realizados CPN apresentou atividades genotóxica, citotóxica, antigenotóxica e anticitotóxica.

APA, Harvard, Vancouver, ISO, and other styles

30

Wagner, Holly A. "Determining optimal load for a constant-load cycle ergometer test relative to isotonic leg strength." Thesis, This resource online, 1992. http://scholar.lib.vt.edu/theses/available/etd-01242009-063426/.

Full text

APA, Harvard, Vancouver, ISO, and other styles

31

Chang, Chun-Ming M. Eng Massachusetts Institute of Technology. "Developing Highly Accelerated Life Test (HALT) method to improve product robustness and shorten development cycle." Thesis, Massachusetts Institute of Technology, 2016. http://hdl.handle.net/1721.1/106687.

Full text

Abstract:

Thesis: M. Eng. in Advanced Manufacturing and Design, Massachusetts Institute of Technology, Department of Mechanical Engineering, 2016. This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections. Cataloged from student-submitted PDF version of thesis. Includes bibliographical references (pages 80-81). Highly Accelerated Life Testing (HALT) is often used to identify the latent defects for the printed circuit boards (PCBs) during the early stage of the product development process. The inconsistency in executing HALT may not reveal the maximum amount of design weaknesses or intermittent failures, which would eventually lead to the premature product failure in the field and incur additional warranty expenses. The scope of this project has focused on establishing the standardized operating procedure (SOP) for Highly Accelerated Life Testing (HALT) using the DMAIC methodology for the electronic components such as printed circuit boards (PCBs) to help identify these latent issues in advance and increase product robustness. In addition to applying statistical tools to optimize several key process parameters such as soaking time and ramp rate, the related failure analysis and corrective actions were also demonstrated in this thesis. In summary, three major results are shown: first, following the DMAIC guideline, the standard operating procedure (SOP) of HALT was established and applicable to all types of printed circuit boards. Secondly, it was shown that the top three failure modes identified in HALT were almost identical to that of the field returns'. Last but not least, the relationship between the operating margins and the warranty replacement rate was also established. Although more data points are required to further consolidate the model, the current result has indicated that there is a declining trend of the warranty replacement rate for every increment of the temperature operating margins. Such mathematical relationship was then used in the economic model to justify the business benefit of HALT. by Chun-Ming Chang. M. Eng. in Advanced Manufacturing and Design

APA, Harvard, Vancouver, ISO, and other styles

32

Santos, Fátima da Conceição Ferreira dos. "Hazard assessment for Nickel nanoparticles in the soil: full life cycle test with Enchytraeus crypticus." Master's thesis, Universidade de Aveiro, 2016. http://hdl.handle.net/10773/18560.

Full text

Abstract:

Mestrado em Toxicologia e Ecotoxicologia A nanotecnologia é uma área em constante crescimento, com cada vez mais produtos contendo nanopartículas (NPs) a serem introduzidos no mercado e no nosso dia-a-dia, desde cosméticos a baterias e dispositivos médicos. As características das NPs (composição química, tamanho, forma, reatividade) prometem novas aplicações e tornam estes materiais altamente desejáveis. Devido ao aumento de produção, as NPs irão eventualmente chegar ao meio ambiente de forma direta ou indireta, onde podem causar efeitos negativos nos diferentes compartimentos dos ecossistemas (solo, ar, água). Apesar de haver estudos ecotoxicológicos que se focam em nanomateriais, diferentes resultados (e por vezes contraditórios) podem ser encontrados mesmo para NPs com a mesma composição química, o que se pode dever a influência de fatores bióticos e abióticos que podem alterar a biodisponibilidade e portanto a toxicidade desses materiais. NPs metálicas, como o níquel (Ni) são atualmente utilizadas em diversas aplicações, no entanto os efeitos das nanopartículas de níquel (NiNPs) em organismos de solo ainda são pouco conhecidos. No presente estudo, a toxicidade de NiNPs (em comparação com NiNO3) para o organismo modelo de solo Enchytraeus crypticus (Oligochaeta) foi investigada com base no teste padrão Teste de Reprodução em Enquitreídeos (em inglês Enchytraeid Reprodução test - ERT) e no recentemente desenvolvido teste de ciclo de vida completo (FLC), que adiciona ao teste padrão, parâmetros como a eclosão, o crescimento e o tempo para atingir a maturidade. No geral, NiNO3 foi mais tóxico para o E. crypticus do que as NiNPs e a toxicidade parece ocorrer através de mecanismos diferenciados. Na exposição a NiNO3, os efeitos foram visíveis na redução do número de juvenis eclodidos ao nível da eclosão e mantiveram-se ao longo de todos os parâmetros avaliados no ciclo de vida (crescimento, estado de maturação, sobrevivência e reprodução). Relativamente à exposição a NiNPs, a eclosão foi o parâmetro mais sensível (CE10 = 47 mg NiNPs/kg), mas os organismos sobreviveram e reproduziram-se a concentrações até 1800 mg NiNPs/kg, mostrando que o efeito observado na eclosão foi um atraso. Exposição a 100 mg Ni/kg causou efeitos similares a concentrações mais altas (1000 e 1800 mg NiNPs/kg) indicando um maior efeito associado ao tamanho nano. Os atuais resultados realçam a potencial falta de uma dose-resposta monótona (com base na massa) para a avaliação de perigo de NPs e consequentemente a exigência da revisão dos procedimentos para a avaliação de risco. Nanotechnology is an area of increasing growth, with more and more products containing nanoparticles (NPs) being introduced in the market and used in our daily life, from cosmetics to batteries and medical devices. NPs characteristics (chemical composition, size, shape, reactivity) promises new applications and make these materials highly desirable. Due to the increase of production NPs will eventually reach the environment either directly or indirectly, where they may cause negative effects in different compartments of ecosystems (soil, air, water). Although there are ecotoxicological studies that focus on nanomaterials, different (and sometimes contradictory) results can be found even with NPs of the same chemical composition, which may be due to the influence of abiotic and biotic factors that can affect the bioavailability and hence the toxicity of those materials Metallic NPs, such as nickel (Ni) are currently used in many applications, however the effects of nickel nanoparticles (NiNPs) in soil organisms are still poorly known. In the present work, the aim was to evaluate the toxicity of NiNPs (compared to NiNO3) for soil model organism Enchytraeus crypticus (Oligochaeta) using the standard Enchytraeid reproduction test (ERT) and the newly developed full life cycle test (FLC ), which adds to the standard the parameters hatching, growth and time to reach maturity. NiNO3 was more toxic to E. crypticus than NiNPs and toxicity seems to occur via differentiated mechanisms. For NiNO3 exposure effects where visible in the reduced number of hatched juveniles and then remained throughout all the endpoints evaluated in the life cycle (growth, maturity status, survival and reproduction). Regarding exposure to NiNPs, hatching was the most sensitive endpoint (EC10 = 47 mg NiNPs/kg), but organisms survived and reproduced at concentrations up to 1800 mg NiNPs/kg, revealing that the effect in the hatching was a delay. Exposure to 100 mg NiNPs/kg caused similar effects to the higher concentrations (1000 and 1800 mg NiNPs/kg), indicating higher nano-particulate effect. These results highlights the potential lack of monotone dose-response (based on mass) for hazard assessment of NPs and hence the requirement of a revised procedure for Risk Assessment.

APA, Harvard, Vancouver, ISO, and other styles

33

Meyer, Mark J. "Understanding the challenges in HEV 5-cycle fuel economy calculations based on dynamometer test data." Thesis, Virginia Tech, 2011. http://hdl.handle.net/10919/35648.

Full text

Abstract:

EPA testing methods for calculation of fuel economy label ratings, which were revised beginning in 2008, use equations that weight the contributions of fuel consumption results from multiple dynamometer tests to synthesize city and highway estimates that reflect average U.S. driving patterns. The equations incorporate effects with varying weightings into the final fuel consumption, which are explained in this thesis paper, including illustrations from testing. Some of the test results used in the computation come from individual phases within the certification driving cycles. This methodology causes additional complexities for hybrid electric vehicles, because although they are required to have charge-balanced batteries over the course of a full drive cycle, they may have net charge or discharge within the individual phases. The fundamentals of studying battery charge-balance are discussed in this paper, followed by a detailed investigation of the implications of per-phase charge correction that was undertaken through testing of a 2010 Toyota Prius at Argonne National Laboratoryâ s vehicle dynamometer test facility. Using the charge-correction curves obtained through testing shows that phase fuel economy can be significantly skewed by natural charge imbalance, although the end effect on the fuel economy label is not as large. Finally, the characteristics of the current 5-cycle fuel economy testing method are compared to previous methods through a vehicle simulation study which shows that the magnitude of impact from mass and aerodynamic parameters vary between labeling methods and vehicle types. Master of Science

APA, Harvard, Vancouver, ISO, and other styles

34

Zabramba, Joachim. "A descriptive study of the First Cycle English Test (FCET) for Burkina Faso secondary schools /." The Ohio State University, 2000. http://rave.ohiolink.edu/etdc/view?acc_num=osu1488196781732838.

Full text

APA, Harvard, Vancouver, ISO, and other styles

35

Yildiz, Erdinc Nuri. "Aeroelastic Stability Prediction Using Flutter Flight Test Data." Phd thesis, METU, 2007. http://etd.lib.metu.edu.tr/upload/12608623/index.pdf.

Full text

Abstract:

Flutter analyses and tests are the major items in flight certification efforts required when a new air vehicle is developed or when a new external store is developed for an existing aircraft. The flight envelope of a new aircraft as well as the influence of aircraft modifications on an existing flight envelope can be safely determined only by flutter tests. In such tests, the aircraft is instrumented by accelerometers and exciters. Vibrations of the aircraft at specific dynamic pressures are measured and transmitted to a ground station via telemetry systems during flutter tests. These vibration data are analyzed online by using a flutter test software with various methods implemented in order to predict the safety margin with respect to flutter. Tests are performed at incrementally increasing dynamic pressures and safety regions of the flight envelope are determined step by step. Since flutter is a very destructive instability, tests are performed without getting too close to the flutter speed and estimations are performed by extrapolation. In this study, pretest analyses and flutter prediction methods that can be used in various flight conditions are investigated. Existing methods are improved and their applications are demonstrated with experiments. A novel method to predict limit cycle oscillations that are encountered in some modern fighter aircraft is developed. The prediction method developed in this study can effectively be used in cases where the nonlinearities in aircraft dynamics and air flow reduce the applicability of the classical prediction methods. Some further methods to reduce the adverse effects of these nonlinearities on the predictions are also developed.

APA, Harvard, Vancouver, ISO, and other styles

36

Hurley, James David. "The cloning and molecular characterisation of cDNA corresponding to a novel form of pituitary adenylate cyclase activating polypeptide (PACAP) mRNA in the rat testis." Thesis, Imperial College London, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.265700.

Full text

APA, Harvard, Vancouver, ISO, and other styles

37

Greiwe, Jeffrey S. "Reliability of VOb2s max estimates from the American College of Sports Medicine submaximal cycle ergometer test." Virtual Press, 1993. http://liblink.bsu.edu/uhtbin/catkey/865962.

Full text

Abstract:

The purpose of this investigation was to determine the reliability and validity of VO2max estimates from the ACSM submaximal cycle ergometer test compared to a maximal cycle ergometer test. Thirty healthy male and female subjects aged 21-54 volunteered for this study. Each subject performed a maximal cycle ergometer test and two ACSM submaximal cycle ergometer tests. At least 48 hours elapsed between the maximal test and the first submaximal test while at least 24 hours elapsed between the two submaximal tests. Heart rates were recorded from a radio telemetry monitor and from 15 second palpation of the radial artery. A trained technician performed all palpations and was blinded from the telemetry monitor during testing to eliminate any bias. Maximal oxygen uptake (VO2max) was estimated by extrapolatingrate for each submaximal trial. To determine inter-test radio telemetry monitor (MON), to an age predicted maximal heart reliability between submaximal trials, correlational analysis andt-test were performed. A correlation of r= .863 and r= .767 were found between the two trials for MON V02max and PALP VO2max respectively. Paired t-test revealed no significant difference (p< .01) between MON V02max 1 and MON VO2max 2 or between PALP V02max 1 and PALP VO2max 2. Although there were no significant differences between trials, the mean data was often not indicative of the individual data since there were 8 MON VO2max cases and 19 PALP VO2max cases where VO2max estimates varied by > 0.5 L/min. There were significant differences between all V02max estimates when compared to measured VO2max and mean percent error in estimates for MON VO2max and PALP VO2max were 25.7% and 33.8%, respectively. The mean error of MON VO2max 1 and MON VO2max 2 were .61 and .63 L/min, respectively. The mean error for PALP VO2max 1 and PALP VO2max 2 were somewhat higher at .90 and .73 L/min, respectively. The present data indicates that a large error is present in VO2max estimates between trials and between measured and estimated VO2max. Therefore, caution must be used when interpreting VO2max estimates from the ACSM submaximal cycle ergometer test. School of Physical Education

APA, Harvard, Vancouver, ISO, and other styles

38

Haag, Lance Edward. "Effective use of test data for quality improvement and cycle time reduction in radio system manufacturing." Thesis, Massachusetts Institute of Technology, 1995. http://hdl.handle.net/1721.1/38107.

Full text

Abstract:

Thesis (M.S.)--Massachusetts Institute of Technology, Sloan School of Management, 1995, and Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 1995. Includes bibliographical references (leaves 66-67). by Lance Edward Haag. M.S.

APA, Harvard, Vancouver, ISO, and other styles

39

Zhang, Yumo. "PILOT SCALE DEMONSTRATION AND EVALUATION OF INNOVATIVE NON-DESLIMED NON-CLASSIFIED GRAVITY-FED HM CYCLONE." UKnowledge, 2015. http://uknowledge.uky.edu/mng_etds/19.

Full text

Abstract:

Coal preparation plants are required in some cases to produce a high-grade product using a low specific gravity cut-point. For these situations, a second higher gravity separation would be desirable to generate a mid-grade product that can be utilized for electricity generation thereby maximizing coal recovery. A study was conducted to evaluate the potential of achieving efficient separations at two different density cut-points in a single stage using a three-product dense medium cyclone. Variations in density cut-point and process efficiency values were quantified as a function of the feed medium density, feed medium-to-coal ratio, and feed pressure using a three-level experimental design program. Results indicate the ability to effectively treat coal over a particle size range from 6mm to 0.15mm while achieving both low- and high-density cut-points up to 1.95 relative density. Ash content decreased from 27.98% in the feed to an average of 7.77% in the clean coal product and 25.76% in the middlings product while sulfur content was reduced from 3.87 to 2.83% in the clean coal product. The overall combustible recovery was maintained above 90% while producing clean coal products with ash and total sulfur content as low as 5.85 and 2.68%, respectively. Organic efficiency values were consistently about 95% and probable error values were in the range of 0.03 to 0.05, which indicates the ability to provide a separation performance equivalent to or better than traditional coal cleaning technologies.

APA, Harvard, Vancouver, ISO, and other styles

40

Guertler, Cynthia L. "Breaking the Cycle: A Mixed-Methods Study of Math Anxiety at the Middle-School Level." Ashland University / OhioLINK, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=ashland147923618054427.

Full text

APA, Harvard, Vancouver, ISO, and other styles

41

Hernandez, Raymundo. "Circulatory and Respiratory Responses to Cycle Ergometry at Different Pedal Rates." Thesis, University of North Texas, 1991. https://digital.library.unt.edu/ark:/67531/metadc503894/.

Full text

Abstract:

The effects of moderate workload exercise at different pedal rates on circulatory and respiratory parameters were studied. Five subjects performed seven discontinuous constant-load cycle ergometer tests of 30 minutes duration at pedal rates of 40, 50, 60, 70, 80, 90 and 100 rpm. Oxygen uptake and carbon dioxide production were determined by standard open circuit spirometry, while heart rate was recorded by electrocardiograph. The CO₂ rebreathing procedure was administered during the exercise bout in order to determine cardiac output. Blood pressure was determined for each test, and total peripheral resistance was calculated. The findings indicate that progressive increases in pedal frequency during discontinuous constant-load cycle ergometry produce progressive increases in cardiovascular, respiratory and metabolic responses and a decrease in gross exercise mechanical efficiency. The results indicate that oxygen uptake, cardiac output, heart rate, ventilation and arterial-venous oxygen difference increases curvilinearly as pedal rate increases, possibly as a result of increases in recruitment of muscle fibers and/or muscle groups. These findings suggest that circulatory and respiratory responses are due to "central command" which sets the basic efferent response pattern. However, this effector pattern is modulated by afferent input originating from the legs during progressive increases in pedal rate.

APA, Harvard, Vancouver, ISO, and other styles

42

Delaux, David. "L'ingénierie de fiabilité dans le cycle de vie des systèmes mécatroniques automobiles Synthesis and validation of accelerated vibration durability tests Validation de la fiabilité des modules de refroidissement moteur par une personnalisation des essais vibratoire, choc thermique et pression cyclée Highly accelerated testing." Thesis, Normandie, 2019. http://www.theses.fr/2019NORMIR10.

Full text

Abstract:

Les travaux de cette thèse permettent d’apporter de nouveaux outils d’aide à la conception d’un système mécatronique appliqué au monde automobile. Ces méthodologies s’inscrivent dans le cycle de vie du produit découpé selon les phases de Fiabilité : Prédictive, Expérimentale et Opérationnelle. Nous répondons aux trois problématiques : 1. Comment juger la criticité d’une défaillance obtenue lors d’un essai aggravé HALT ? Une approche par équivalence d’endommagement est utilisée et appliquée à un cas concret d’onduleur/convertisseur. 2. Comment tenir compte des variabilités du matériau et de l’environnement dans le modèle d’Arrhenius ? Trois modèles statistiques sont construits et appliqués à un capteur mécatronique en essai climatique. 3. A partir des données financières de coûts garantie, comment estimer la fiabilité du système ? Deux nouveaux modèles probabilistes sont présentés et appliqués à un cas réel de retour garantie This research proposes new tools for designers of automotive mechatronic systems. These new methods are linked with the Product Life Cycle which can be described by: Predictive Reliability, Experimental Reliability and Operational Reliability. Three problematics are exposed : 1. How can we judge the severity of a failure observed in aggraved test HALT? An equivalent fatigue damage approach is used and realized on concrete case of converter/inverter. 2. How can we take into account the variability of the material and the environment in the Arrhenius’ model ? Three statistical models are built and used on a mechatronic sensor in climatic test. 3. Thanks Financial data of warranty cost, how can we estimate the system reliability performance ? Two new probabilistic models are introduced and applied on concrete warranty returns

APA, Harvard, Vancouver, ISO, and other styles

43

Bouchard, Carole. "Compréhension des items du South Oaks Gambling Screen chez des enfants du deuxième cycle du primaire." Master's thesis, Université Laval, 1999. http://hdl.handle.net/20.500.11794/40635.

Full text

Abstract:

Peu d’études s’intéressent aux habitudes de jeu des enfants. En 1996, Ladouceur, Ferland, Jacques, et Boudreault notent que 4,5% des enfant âgés de 9 à 12 ans montrent les caractéristiques du jeu pathologique. Ceci constitue un taux deux fois plus élevé que chez les adultes. Réalisée auprès de 84 élèves du primaire, la présente étude examine la compréhension du questionnaire employé par ces chercheurs, soit le South Oaks Gambling Screen-Adolescent Version (SOGS-RA, Winters, Stinchfîeld, & Fulkerson, 1993). Les résultats de cette étude indiquent que près d’une question sur trois est incomprise. Plus le score au SOGS-RA est élevé, moins la compréhension du questionnaire est bonne. Cependant, la compréhension n’est pas reliée au niveau de scolarité. Des explications favorisent une diminution des scores lors d’une seconde passation. La discussion souligne les implications pratiques et théoriques de ces résultats et offre des suggestions pour l’élaboration d’un nouvel instrument de mesure.

APA, Harvard, Vancouver, ISO, and other styles

44

Beaulieu, Maryse. "Élaboration d'une grille d'analyse de matériels didactiques informatisés pour l'apprentissage de la numérotation au premier cycle du primaire." Sherbrooke : Université de Sherbrooke, 2003.

Find full text

APA, Harvard, Vancouver, ISO, and other styles

45

Masclet, Eddy Michel Maurice. "L'explication du phénomène des saisons chez les élèves du cycle III : test d'une séquence d'enseignement et ingénierie didactique." Paris 7, 2003. http://www.theses.fr/2003PA070012.

Full text

Abstract:

Le travail consiste en une démarche d'ingénierie didactique relative à l'enseignement de l'astronomie au cycle III, de la forme de la Terre au phénomène des saisons, en France. Nous avons tester trois hypothèses reposant sur l'influence du développement cognitif au sens piagétien, l'influence de la prise en compte des conceptions initiales et l'influence de la manipulation lors de phases de modélisation ou d'expérimentation sur la compréhension de la séquence. Leur test dans vingt et une classes expérimentales proches du socio-constructivisme par le chercheur et par dix professeurs des écoles, puis dans quatre classes (deux classes repères proches du transmissif et deux classes repères intermédiaires) ont permis de découvrir l'importance du développement cognitif de l'élève sur la compréhension de la séquence, notamment pour ce qui concerne l'espace projectif, le lien entre le développement cognitif et la conception, le lien entre la conception initiale et la compréhension de la séquence, l'efficacité d'une séquence s'inspirant du socio-constructivisme à travers la prise en compte des conceptions initiales et les manipulations, l'importance de l'argumentation orale et écrite lors des séances The work consists of a method of didactic engineering relative to the education of the astronomy to children from 8 to 11 years old, the shape of the Earth until the phenomenon of the seasons, in France. We have tested three hypotheses based on the effect of cognitive development, the effect of taking into account initial conceptual understanding and the effect of manipulation during phases of modelling and experimentation based on the comprehension of the sequence. Their test in twenty one experimental classes close to the socio-constructivism by the researcher and by ten primary teachers, then in four classes (two reference classes close to the transmissive approach and the two classes intermediate) allowed to discover the importance of the cognitive development of the pupil on the understanding of the sequence, notably as regards the projective space, the link between the cognitive development and the conception, the link between the initial conception and the understanding of the sequence, the efficiency of a sequence being inspired by the socio-constructivism through the taking into account of the initial conceptions and the manipulations, the importance of the argumentation oral and written

APA, Harvard, Vancouver, ISO, and other styles

46

Andersson, Claes. "Fusing Domain Knowledge with Data : Applications in Bioinformatics." Doctoral thesis, Uppsala universitet, Centrum för bioinformatik, 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-8477.

Full text

Abstract:

Massively parallel measurement techniques can be used for generating hypotheses about the molecular underpinnings of a biological systems. This thesis investigates how domain knowledge can be fused to data from different sources in order to generate more sophisticated hypotheses and improved analyses. We find our applications in the related fields of cell cycle regulation and cancer chemotherapy. In our cell cycle studies we design a detector of periodic expression and use it to generate hypotheses about transcriptional regulation during the course of the cell cycle in synchronized yeast cultures as well as investigate if domain knowledge about gene function can explain whether a gene is periodically expressed or not. We then generate hypotheses that suggest how periodic expression that depends on how the cells were perturbed into synchrony are regulated. The hypotheses suggest where and which transcription factors bind upstreams of genes that are regulated by the cell cycle. In our cancer chemotherapy investigations we first study how a method for identifiyng co-regulated genes associated with chemoresponse to drugs in cell lines is affected by domain knowledge about the genetic relationships between the cell lines. We then turn our attention to problems that arise in microarray based predictive medicine, were there typically are few samples available for learning the predictor and study two different means of alleviating the inherent trade-off betweeen allocation of design and test samples. First we investigate whether independent tests on the design data can be used for improving estimates of a predictors performance without inflicting a bias in the estimate. Then, motivated by recent developments in microarray based predictive medicine, we propose an algorithm that can use unlabeled data for selecting features and consequently improve predictor performance without wasting valuable labeled data.

APA, Harvard, Vancouver, ISO, and other styles

47

Acimovic, Aleksandar, and Aleksandar Bajceta. "Test script design approaches supporting reusability, maintainability and review process." Thesis, Mälardalens högskola, Akademin för innovation, design och teknik, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:mdh:diva-44724.

Full text

Abstract:

Software testing is widely considered to be one of the most important parts of software development life-cycle. In this research, we investigated potential improvements in the testing process and design of automated test scripts inside Bombardier Transportation. For the creation of automated test scripts BT is using a group of programs called TAF (Test Automation Framework). These scripts are used for testing Train Control Management System (TCMS), software that is used for managing the train. TAF can export its test scripts in XML format. XML scripts are analyzed in order to identify the most frequent changes. To better understand the life cycle of automated Test scripts official documentation that defines the Verification and Validation process inside BT was analyzed. Also, an interview was conducted with one of the responsible persons for testing. We believe that we have found a possible solution for improving testing process and creation of automated test scripts in BT, and to evaluate it proof of concept tool was developed. The main idea behind the tool is to write the test script using keywords which are based on analysis that was conducted on test specification documentation. These keywords represent frequent actions that are being tested on the train. By storing those actions in keywords re-usability of test script is being increased. Also, because they are based on naturally language, they are having positive effect on readability and maintenance of the test script.

APA, Harvard, Vancouver, ISO, and other styles

48

Garcia-Dastugue, Sebastian Javier. "Dynamic time-based postponement: conceptual development and empirical test." The Ohio State University, 2003. http://rave.ohiolink.edu/etdc/view?acc_num=osu1061377587.

Full text

APA, Harvard, Vancouver, ISO, and other styles

49

Meneghello, Raphael. "Busca e caracterização de inibidores da enzima DacA de Staphylococcus aureus." Universidade de São Paulo, 2016. http://www.teses.usp.br/teses/disponiveis/76/76132/tde-14102016-103118/.

Full text

Abstract:

Recentemente, uma molécula baseada em nucleotídeos, a adenosina monofosfato dimérica cíclica (c-di-AMP), foi identificada em várias bactérias patogênicas, ganhando rapidamente o status de um sinalizador central no controle de diversos processos bacterianos essenciais, tais como transporte iônico e vigilância a danos no DNA. Em Staphylococcus aureus, por exemplo, o c-di-AMP é essencial para homeostase da parede celular e resistência aos estresses ambientais. A biossíntese de c-di-AMP envolve a condensação de duas moléculas de ATP, catalisadas por enzimas que contenham o domínio DAC (diadenilato ciclase). Especialmente em S. aureus, somente uma ciclase (DacA) é responsável pela síntese desse segundo-mensageiro, através da enzima DacA. Recentemente, nosso grupo determinou a estrutura da DacA de S. aureus, demonstrando a importância do seu estado oligomérico para o mecanismo catalítico. Diferentemente da primeira diadenilato caracterizada, a DisA, uma enzima octamérica, a atividade enzimática da DacA ocorre através do encontro de dois dímeros distintos, formando uma interface cataliticamente competente. Dadas essas características, o foco desse trabalho foi a busca de novos inibidores para a DacA, através de triagens em larga escala (HTS), triagem cristalográfica por fragmentos e docagem molecular. Foram encontrados 30 compostos com atividade inibitória nos ensaios de HTS, 15 compostos derivados de fragmentos da triagem cristalográfica e construída uma biblioteca de 480 compostos docados virtualmente no sítio ativo. Os compostos encontrados na triagem cristalográfica foram caracterizados com respeito ao seu valor de IC50 frente à atividade enzimática. O composto AN-584/43409544 se demonstrou bastante promissor, com valor de IC50 de 54 µM. Ainda, um análogo desse composto foi encontrado na interface dimérica da DacA nos estudos cristalográficos, o que mostra um possível sítio alostérico para o desenvolvimento e busca de inibidores. Os resultados gerados nesse projeto podem servir de base para estudos futuros e desenvolvimento de novos antibióticos, que em combinação com os tratamentos atualmente disponíveis pode levar ao controle das infecções até mesmo das formas mais resistentes de S. aureus. Recently, a nucleotide-based molecule, the cyclic dimeric adenosine monophosphate (c-di-AMP), has been identified in several pathogenic bacteria, rapidly gaining the status of a central signaling controlling several essential bacterial processes, such as ion transport and DNA damage surveillance. In Staphylococcus aureus, for example, c-di-AMP is essential for homeostasis of the cell wall and resistance to environmental stresses. The biosynthesis of c-di-AMP involves the condensation of two molecules of ATP, catalyzed by enzymes that contain the DAC (diadenylate cyclase) domain. Especially in S. aureus, only one cyclase (DacA) is responsible for the synthesis of this second-messenger. Recently, our group determined the structure of the S. aureus diadenylate cyclase, demonstrating the importance of their oligomeric state for the catalytic mechanism. Unlike DisA, a octameric diadenylate cyclase, the enzymatic activity of DacA occurs through the meeting of two dimers forming a catalytically competent interface. Given these characteristics, the focus of this work was the search for new inhibitors through high-throughput screening (HTS), crystallographic screening of fragments and molecular docking. It was found 30 compounds with inhibitory activity in HTS assays, 15 compounds derived from fragments of crystallographic screening and built a 480 compound library virtually docked in the active site. The compounds found in the crystallographic screening were characterized with respect to its IC50 value. The compound AN-584/43409544 has been shown verry promising, with IC50 of 54 µM. Also, an analog of this compound was found in the dimeric interface of DacA in crystallographic assays, which shows a possible allosteric site for inhibitors search and development. The results generated in this project can serve as a basis for future studies and development of new antibiotics, which in combination with the currently available treatments can lead to infection control even of the most resistant strains of S. aureus.

APA, Harvard, Vancouver, ISO, and other styles

50

Rabah-Romdhane, Zohra. "Etudes sur le cycle économique. Une approche par les modèles à changements de régime." Thesis, Université de Lorraine, 2013. http://www.theses.fr/2013LORR0322.

Full text

Abstract:

L'ampleur de la Grande Récession a suscité un regain d'intérêt pour l'analyse conjoncturelle, plus particulièrement du cycle économique. Notre thèse participe de ce renouveau d'attention pour l'étude des fluctuations économiques.Après une présentation générale des modèles à changements de régime dans le chapitre 1, le chapitre suivant propose une chronologie du cycle des affaires de l'économie française sur la période 1970-2009. Trois méthodes de datation sont utilisées à cette fin : la règle des deux trimestres consécutifs de croissance négative, l'approche non paramétrique de Bry et Boschan (1971) et le modèle markovien à changements de régime de Hamilton (1989). Les résultats montrent que l'existence de ruptures structurelles peut empêcher ce dernier modèle d'identifier correctement les points de retournement cycliques. Cependant, quandces ruptures sont prises en considération, le calendrier des récessions françaises obtenu à l'aide du modèle d'Hamilton coïncide largement avec celui obtenu par les deux autres méthodes. Le chapitre 3 développe une analyse de la non-linéarité dans le modèle à changements de régime en utilisant un ensemble de tests non-standards. Une étude par simulation Monte Carlo révèle qu'un test récemment proposé par Carrasco, Hu et Ploberger (2013) présente une faible puissance pour des processus générateurs des données empiriquement pertinents et ce, lorsqu'on tient compte de l'autocorrélation sous l'hypothèse nulle. En revanche, untest "bootstrap" paramétrique basé sur le rapport des vraisemblances a, pour sa part une puissance plus élevée, ce qui traduit l'existence probable de non-linéarités significatives dans le PIB réel trimestriel de la France et des Etats-Unis. Quand il s'agit de tester un changement de régime en moyenne ou en constante, il est important de tenir compte de l'autocorrélation sous l'hypothèse nulle de linéarité. En effet, dans le cas contraire, un rejet de la linéarité pourrait simplement refléter une mauvaise spécification de la persistance des données, plutôt que d'une non-linéarité inhérente.Le chapitre 4 examine une question importante : la considération de ruptures structurelles dans les séries améliore-t-elle la performance prédictive du modèle markovien relativement à son homologue linéaire ? La démarche adoptée pour y répondre consiste à combiner les prévisions obtenues pour différentes périodes d'estimation. Voici le principal résultat dû à l'application de cette démarche : la prise en compte des données provenant des intervalles de temps précédant les ruptures structurelles et la "Grande Modération" améliore les prévisions basées sur des données tirées exclusivement de ces épisodes. De la sorte, les modèles à changements de régime s'avèrent capables de prédire la probabilité d'événements tels que la Grande Récession, avec plus de précision que ses homologues linéaires.Les conclusions générales synthétisent les principaux acquis de la thèse et évoqueplusieurs perspectives de recherche future The severity of the Great Recession has renewed interest in the analysis of business cycles. Our thesis pertains to this revival of attention for the study of cyclical fluctuations. After reviewing the regime-switching models in Chapter one, the following chapter suggests a chronology of the classical business cycle in French economy for the 1970-2009 period. To that end, three dating methodologies are used: the rule of thumb of two consecutive quarters of negative growth, the non-parametric approach of Bry and Boschan (1971), and the Markov-switching approach of Hamilton (1989). The results show that,omitted structural breaks may hinder the Markov-switching approach to capture business-cycle fluctuations. However, when such breaks are allowed for, the timing of the French recessions provided by the Markov-switching model closely matches those derived by the rule-based approaches.Chapter 3 performs a nonlinearity analysis inMarkov-switching modelling using a set of non-standard tests. Monte Carlo analysis reveals that a recently test proposed by Carrasco, Hu, and Ploberger (2013) for Markov switching has low power for empirically-relevant data generating processes when allowing for serial correlation under the null. By contrast, a parametric bootstrap likelihood ratio (LR) test of Markov switching has higher power in the same setting, providing stronger support for nonlinearity in quarterly French and U.S. real GDP. When testing for Markov switching in mean or intercept of an autoregressive process, it is important to allow for serial correlation under the null hypothesis of linearity.Otherwise, a rejection of linearity could merely reflect misspecification of the persistence properties of the data, rather than any inherent nonlinearity.Chapter 4 examines whether controlling for structural breaks improves the forecasting performance of the Markov-switching models, as compared to their linear counterparts.The approach considered to answer this issue is to combined forecasts across different estimation windows. The outcome of applying such an approach shows that, including data from periods preceding structural breaks and particularly the "Great Moderation" improves upon forecasts based on data drawn exclusively from these episodes. Accordingly, Markov-switching models forecast the probability of events such as the Great Recession more accurately than their linear counterparts.The general conclusions summarize the main results of the thesis and, suggest several directions for future research

APA, Harvard, Vancouver, ISO, and other styles

Dissertations / Theses on the topic 'Tests en cyclage'

Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles