Дисертації з теми "Presque accident"

La présente thèse, intitulée "Transformation de l'activité d'apprenants de l'enseignement professionnel en situation de presque accident : Une approche énactive", se focalise sur l'impératif de la prévention des accidents des apprenants dans l'enseignement agricole pendant leur période de formation professionnelle en entreprise. L'objectif est l'exploration de l'activité des apprenants en situation professionnelle risquée, avec une attention particulière sur la population de jeunes travailleurs. La recherche vise à déchiffrer leurs comportements et leurs attitudes face à des situations risquées et à déceler les variables influençant leurs processus de prise de décision, offrant ainsi une meilleure compréhension des enjeux liés à la santé et à la sécurité au travail (S&ST). La méthodologie adoptée repose sur l'intersection de la psychophénoménologie de Vermersch (Vermersch, 2012; Depraz et al., 2011) et de l'entretien d'explicitation, en adéquation avec le Programme Empirique de Recherche du Cours d'Action émanant du paradigme énactif de Theureau (2004a,2015). Cette méthodologie est exploitée pour scruter les situations de travail des apprenants en situation de presque accident, à savoir des situations qui auraient pu résulter sur un accident. Cette recherche qualitative et heuristique inclut 11 études de cas : cinq entretiens menés avec des apprentis en Centre de Formation d'Apprentis, trois avec des élèves en Maison Familiale Rurale et trois avec des élèves en formation initiale dans des lycées agricoles. L'intention est d'expliquer, par le biais des entretiens d'explicitation, l'expérience éprouvée lors de situations de presque accidents, sans conjecturer sur les apprentissages, et de repérer les facteurs qui ont pu influencer la protection des apprenants. Dans cette optique, le but principal est de capter l'expérience subjective des apprenants pour comprendre comment leur activité se transforme durant ce moment spécifique, qualifié de "moment de renversement" (t=r). L'analyse des "Cours d'expérience" contribue à la compréhension des éléments ayant mené au presque accident, en mettant en exergue les transformations de l'activité. Les résultats de cette recherche révèlent l'intentionnalité ambivalente des apprenants, qui se traduit par leur volonté de répondre à la fois à des attentes sociales et personnelles tout en prenant des risques pour prouver leur compétence. Plusieurs préoccupations influencent la transformation de l'activité lors de leurs prises de décision, notamment un éventail d'émotions variées, de la confiance à l'incompréhension, en passant par la fierté, la colère envers soi-même, la déception et la peur. D'autres éléments méritent d'être soulignés : un fort engament dans les tâches, la détermination de réussir, l'évitement des retards, le respect des délais, une grande attention aux détails et aux repères, telles l'heure du déjeuner, ainsi qu'une anticipation des tâches à effectuer : une réaction rapide et efficace face à des situations risquées, une autocritique marquée et un sentiment de culpabilité en cas d'échec. Ces conclusions insinuent des implications potentielles pour la prévention des accidents et une amélioration de l'approche de la S&ST chez les apprenants. Enfin, cette thèse permet de mettre en lumière l'importance de prendre en compte les niveaux de significations et les dimensions contextuelles relatives aux apprenants durant leur stage par les acteurs engagés dans leur formation
The thesis entitled « Transformation of vocational learners’ activities in near-accident situations An enactive approach » focuses on the imperative of preventing accidents among learners in agricultural education during their professional training period in companies. The goal is to explore learner activity in risky professional situations, with particular attention to the population of young workers. It aims to decipher their behaviors and attitudes in potentially dangerous situations and identify variables influencing their decision-making processes, thereby enhancing understanding of issues related to occupational health and safety (OHS). Themethodology adopted relies on the intersection of Vermersch’s psychophenomenology Vermersch, 2012; Depraz et al., 2011) and the explicitation interview, combined with the Empirical Research Program of Course of Action within the enactive paradigm proposed by Theureau (2004a, 2015). This theoretical combination enables the analysis of learners’ work ituations in near-accident scenarios, which refer to situations that could have resulted in an accident. This qualitative and heuristic study comprises 11 case studies : five interviews with apprentices in Apprenticeship Training Centers, three with students in Rural Family Houses, and three with students in initial training in agricultural high schools. The aim is to describe, through xplicitation interviews, the lived experience during near-accident situations, without making prior assumptions about the learning process, and to identify factors that have facilitated or indered the learners’ protection. In this perspective, the primary objective is to capture the subjective experience of learners in order to understand how their activity transforms during this specific moment, referred to as the « moment of reversal » (t = r ). The analysis of « courses of experience » allows for understanding the factors that led to the incident, shedding light on the transformations of the activity. The results of this research reveal the intentional ambivalence of learners, manifested by their dual intention to meet social and personal expectations while taking risks to demonstrate their competence. Various fundamental concerns influence the transformation of young individuals’ activity during their decision-making processes, including contrasting emotions ranging from confidence to incomprehension, as well as feelings of pride and anger towards oneself, disappointment, and fear. Furthermore, a strong determination to fully engage in tasks, to succeed, to avoid delays and meet deadlines, a particular attention to details and landmarks, such as lunchtime, and anticipation of tasksto be accomplished, quick and effective reactions to unexpected or dangerous situations (sometimes surprising), and a pronounced self-critique and sense of guilt in case of failure. These results suggest potential implications for accident prevention and improvement in the pproach to health and safety at work among learners. The thesis emphasizes the necessity for actors involved in learner training during their work placements to consider the levels of leaning and contextual dimensions relevant to the learner

L’aorte est une artère majeure et la rupture de l’aorte (RA) est la lésion la plus commune parmi les larges vaisseaux. Une RA est détectée dans 10 à 15% des cas mortels liés aux accidents de voiture et constitue la cause secondaire des morts consécutives aux chocs traumatiques associés à ces accidents. Les mécanismes variés de RA (éclatement soudain de l’aorte, la contrainte des structures osseuses, le « coup de bélier » et la combinaison de ces mécanismes) peuvent être considérés comme une combinaison de deux types de contributions : la distraction aortique et la pression aortique.L’objectif de ce travail de doctorat est d’étudier les mécanismes liés aux RAs dans les accidents de voitures en se focalisant sur les mécanismes associés à la pression intra-aortique. Le travail est organisé en quatre parties : 1) quantifier la réponse aortique sous des conditions de chargement physiologiques, 2) identifier la nécessité de considérer la pression intra-aortique dans les RA associés aux accidents, 3) développer un modèle d’éléments finis incluant la contribution des mécanisme de lésions et 4) et finalement étudier le mécanisme de RA avec le modèle nouvellement développé
Blunt aortic rupture (BAR) is the second leading cause of death following blunt trauma in motor vehicle crash accidents (MVCAs). Aortic distraction was postulated to be a primary BAR mechanism, but intra-aortic pressure effect on BAR is controversial. Previous finite element (FE) simulations did not simultaneously study the BAR mechanisms of the two contribution sources. Therefore, the BAR mechanisms remain to be ascertained under the effects of physiological intra-aortic pressure and intra-thoracic interactions during MVCAs.Our objective is to investigate BAR mechanisms in MVCAs with a focus on intra-aortic pressure. The work is organized: 1) to quantify aortic responses under cardiac function, 2) to identify the necessity of considering intra-aortic pressure, 3) to develop a FE model including both injury contribution sources and 4) to investigate BAR mechanism during MVCA with the new model. The aortic responses under cardiac loadings should be considered for BAR. Intra-aortic pressure could induce a significant BAR risk. BAR in MVCA resulted from a combined mechanism with aortic stretch and intra-aortic pressure as the primary and secondary cause

La catastrophe est un événement ponctuel ou sériel, d'origine naturelle ou humaine et qui touche de nombreuses victimes en causant d'importants dégâts. Générateur d'un fort impact émotionnel, elle est un fait d'actualité justifiant un traitement médiatique. Ce traitement a vocation à informer le public. Il va osciller entre recherche de vérité et quête de profit pour les médias. Si la recherche de vérité est louable, elle peut parfois aboutir à la mise en cause de personnes ou d'institutions. Cette mise en cause participe du travail d'information et n'est, dès lors qu'elle est justifiée, pas contestable. En revanche, si cette dernière est abusive, elle entrera dans le champ pénal et aura vocation à être sanctionnée par le biais des infractions de presse. Le fait de rapporter la catastrophe peut également emporter d'autres conséquences judiciaires. Si la préservation du droit à l'information est primordiale, l'exposition d'un événement, particulièrement celui de la catastrophe est parfois abusif. Cet abus est le fruit d'une surenchère dans le sensationnalisme, comportement justifié par une quête de profit. Constitutifs d'infractions ou source de préjudice, ces comportements sont sanctionnés et ouvrent droit à réparation. Au delà, l'exposition de la catastrophe peut parfois, en dehors de tout abus, être source de préjudice qu'il convient d'indemniser.

Hospitalised patients experience harm as a consequence of adverse events, including inpatient falls and hospital-acquired pressure ulcers. Nurses are attempting to address this situation with the development of international initiatives aimed at improving the safety and quality of nursing care. Evidence to support the implementation of these initiatives is limited, yet widespread implementation continues. The aim of this study was to understand the implementation, impact and sustainment of an initiative to transform nursing care in four acute medical-surgical units. The focus of the initiative was to provide a patient centred framework to improve the safety and quality of nursing care. A number of interventions were implemented such as clinical bedside handover and rounding. This study was conducted in two phases. Phase One used a non-equivalent control group design with historical controls and an uncontrolled interrupted time series. More than 10,000 patients discharged between July 2008 and December 2010 were included. Patients discharged during the initial three months of implementation, were excluded. Two nurse-sensitive indicators were used as outcome measures; inpatient falls and hospital-acquired pressure ulcers. Coded administrative data were analysed using statistical process control to identify changes in the nurse-sensitive indicators over time.
Thesis (PhD Doctorate)
Doctor of Philosophy (PhD)
School of Nursing and Midwifery
Griffith Health
Full Text

The casualty rate of road vehicle accidents in South Africa is one of the highest in the world. This trend has persisted with little variation over the years, despite the efforts of local road safety organisations and research institutions to decrease them. Some of these road vehicle accidents are due to a mechanical failure of the vehicle. The main goal of this study is to establish how high the incidence of mechanical failure is in these accidents. And further to assess if these percentages of mechanical failures do coincide with trends already indicated nationally as well as internationally. Detailed information on the condition of vehicles was collected in and around the Pretoria area. Surveys were conducted to obtain local road and traffic information about vehicle conditions. The one survey was defined as Potential Mechanical Defect Tests (PMDT) where vehicles were stopped and given a brief mechanical inspection, and the other was a Minibus Survey where information was obtained about the age of the vehicle and the overall condition and pressure of tyres. Additional information was obtained from the Accident Response Unit (ARU) and the Forensic Sciences Laboratories, both of the South African Police Services in Pretoria. The findings of the study are that according to the data collected by the ARU over a period of 2,5 years, on average 3,3% of the accidents reported per year in the region were caused by mechanical failures. These identified percentages correspond with values obtained for international countries. The PMDT data indicate that 40% of the vehicles surveyed in suburban areas and 29% of the vehicles surveyed on the highway had mechanical defects that contravened current road and traffic regulations. The difference between the percentages indicates that the condition of vehicles inspected in the suburban area differs significantly from the condition of those using the highway. In the Minibus Survey, large irregularities in tyre pressure were identified as cause for concern. In general, all of the above findings indicated that maintenance on older vehicles seemed to receive less attention. It is proposed that annual vehicle inspections should be introduced, especially for vehicles carrying fare-paying passengers, to improve road safety standards on South African roads.
Dissertation (M Eng (Mechanical Engineering))--University of Pretoria, 2006.
Mechanical and Aeronautical Engineering
unrestricted

The goal of the present study is to investigate the effect of different scenarios of core degradation in a Nordic-type BWR (boiling water reactor) on the reactor pressure vessel failure mode and timing. Specifically we consider the effects of (i) in-vessel pressure, (ii) melt properties. Control rod guide tube (CRGT) cooling and cooling of the debris from the top are considered as severe accident management (SAM) measures in this study. We also consider the question about minimal amount of debris that can be retained inside the reactor pressure vessel (RPV). Analysis is carried out with coupled (i) Phase-change Effective Convectivity (PECM) model implemented in Fluent for prediction of the debris and melt pool heat transfer, and (ii) structural model of the RPV lower head implemented in ANSYS for simulation of thermo-mechanical creep. The coupling is done through transient thermal load predicted by PECM and applied as a boundary condition in ANSYS analysis. Results of the analysis suggest that applying only CRGT and top cooling is insufficient for maintaining vessel integrity with 0.4 m deep (~12 tons) corium melt pool. The failure of the vessel by thermally induced creep can be expected starting from 5.3 h after the dryout of the debris bed in the lower plenum. However, earlier failure of the instrumentation guide tubes (IGTs) is possible due to melting of the nozzle welding. The internal pressure in the vessel in the range between 3 to 60 bars has no significant influence on the mode and location of the global RPV wall failure. However, depressurization of the vessel can delay RPV wall failure by 46 min for 0.7 m (~ 30 tons) and by 24 min for 1.9 m (~ 200 tons) debris bed. For 0.7 m pool case, changes in vessel pressure from 3 to 60 bars caused changes in liquid melt mass and superheat from ~18 tons at 180 K to ~13 tons at 100 K superheat, respectively. The same changes in pressure for 1.9 m case caused changes in liquid melt mass and superheat from ~40 tons at 42 K to ~10 tons at about 8 K superheat, respectively. Investigation of the influence of melt pool properties on the mode and timing of the vessel failure suggest that the thermo-mechanical creep behavior is most sensitive to the thermal conductivity of solid debris. Both vessel wall and IGT failure timing is strongly dependent on this parameter. For given thermal conductivity of solid debris, an increase in Tsolidus or Tliquidus generally leads to a decrease in liquid melt mass and superheat at the moment of vessel wall failure. Applying models for effective thermal conductivity of porous debris helps to further reduce uncertainty in assessment of the vessel failure and melt ejection mode and timing. Only in an extreme case with Tsolidus, Tliquidus range larger than 600 K, with thermal conductivity of solid 0.5 W∙m‑1∙K‑1 and thermal conductivity of liquid melt 20 W∙m‑1∙K‑1, a noticeable vessel wall ablation and melting of the crust on the wall surface was observed. However, the failure was still caused by creep strain and the location of the failure remained similar to other considered cases.
APRI-8

Considering the unlikely core melt down scenario for a light water reactor (LWR) a possible failure mode of the reactor pressure vessel (RPV) and its failure time has to be investigated for a determination of the loadings on the containment. Worldwide several experiments have been performed accompanied with material properties evaluation, theoretical, and numerical work. At the Institute of Safety Research of the FZR a finite element model has been de-veloped simulating the thermal processes and the viscoplastic behaviour of the ves-sel wall. An advanced model for creep and material damage has been established and has been validated using experimental data. The thermal and the mechanical calculations are sequentially and recursively coupled. The model is capable of evalu-ating fracture time and fracture position of a vessel with an internally heated melt pool. The model was applied to pre- and post test calculations for the FOREVER test se-ries representing the lower head RPV of a PWR in the geometrical scale of 1:10. These experiments were performed at the Royal Institute of Technology in Stock-holm. The results of the calculations can be summarised as follows: # The creeping process is caused by the simultaneous presence of high tem-perature (>600 °C) and pressure (>1 MPa) # The hot focus region is the most endangered zone exhibiting the highest creep strain rates. # The exact level of temperature and pressure has an influence on the vessel failure time but not on the failure position # The failure time can be predicted with an uncertainty of 20 to 25%. This uncer-tainty is caused by the large scatter and the high temperature sensitivity of the viscoplastic properties of the RPV steel. # Contrary to the hot focus region, the lower centre of the vessel head exhibits a higher strength because of the lower temperatures in this zone. The lower part moves down without significant deformation. Therefore it can be assumed, that the vessel failure can be retarded or prevented by supporting this range. # The development of a gap between melt crust and vessel wall could not be proofed. First calculations for a PWR geometry were performed to work out differences and commonalities between prototypic scenarios and scaled experiments. The results of the FOREVER-experiments cannot be transferred directly to PWR geometry. The geometrical, mechanical and thermal relations cannot be scaled in the same way. Because of the significantly higher temperature level, a partial ablation of the vessel wall has to be to expected in the PWR scenario, which is not the case in the FOREVER tests. But nevertheless the FOREVER tests are the only integral in-vessel retention experiments up to now and they led to a number of important insights about the behaviour of a vessel under the loading of a melt pool and pressure.

Considering the unlikely core melt down scenario for a light water reactor (LWR) a possible failure mode of the reactor pressure vessel (RPV) and its failure time has to be investigated for a determination of the loadings on the containment. Worldwide several experiments have been performed accompanied with material properties evaluation, theoretical, and numerical work. At the Institute of Safety Research of the FZR a finite element model has been de-veloped simulating the thermal processes and the viscoplastic behaviour of the ves-sel wall. An advanced model for creep and material damage has been established and has been validated using experimental data. The thermal and the mechanical calculations are sequentially and recursively coupled. The model is capable of evalu-ating fracture time and fracture position of a vessel with an internally heated melt pool. The model was applied to pre- and post test calculations for the FOREVER test se-ries representing the lower head RPV of a PWR in the geometrical scale of 1:10. These experiments were performed at the Royal Institute of Technology in Stock-holm. The results of the calculations can be summarised as follows: # The creeping process is caused by the simultaneous presence of high tem-perature (>600 °C) and pressure (>1 MPa) # The hot focus region is the most endangered zone exhibiting the highest creep strain rates. # The exact level of temperature and pressure has an influence on the vessel failure time but not on the failure position # The failure time can be predicted with an uncertainty of 20 to 25%. This uncer-tainty is caused by the large scatter and the high temperature sensitivity of the viscoplastic properties of the RPV steel. # Contrary to the hot focus region, the lower centre of the vessel head exhibits a higher strength because of the lower temperatures in this zone. The lower part moves down without significant deformation. Therefore it can be assumed, that the vessel failure can be retarded or prevented by supporting this range. # The development of a gap between melt crust and vessel wall could not be proofed. First calculations for a PWR geometry were performed to work out differences and commonalities between prototypic scenarios and scaled experiments. The results of the FOREVER-experiments cannot be transferred directly to PWR geometry. The geometrical, mechanical and thermal relations cannot be scaled in the same way. Because of the significantly higher temperature level, a partial ablation of the vessel wall has to be to expected in the PWR scenario, which is not the case in the FOREVER tests. But nevertheless the FOREVER tests are the only integral in-vessel retention experiments up to now and they led to a number of important insights about the behaviour of a vessel under the loading of a melt pool and pressure.

La recherche analyse la fluctuation, sur cinquante ans, des seuils de tolérance envers l'insécurité routière. Premièrement, la recherche s'interroge, sur la façon dont l'accident routier colporte et produit des représentations sociales. Divers procédés sont alors exploités pour souligner le drame : images spectaculaires, expressions du tragique, titres chocs qui viennent resserrer l'attention du lecteur, le faire frissonner et l'émouvoir. Ensuite, l'étude montre comment en cinquante ans, la société française est passée de l'idée fataliste que l'accident était la contrepartie obligée de la mobilité à la certitude que l'insécurité peut être vaincue par des actions préventives et répressives. Enfin, la sécurité routière apparaît comme un "fait social total". L'accident dévoile brutalement les conditions d'existence et les inégalités socio-professionnelles des usagers de la route. Il renseigne également sur les valeurs de la société dans laquelle il se produit. Depuis quelques années, la sécurité routière est aussi devenue un instrument de pression politique
The study focuses on the fluctuation of levels of tolerance regarding road insecurity within the period of fifty years. Firstly, the study looks at the way road accident peddles and produces social representations. Various procedures then are explored to underline the drama : spectacular pictures, expressions of the tragic, shocking headlines that come to attract the reader's attention by provoking amazement and deep emotions. Secondly, the study shows how in fifty years the French society has shifted from the fatalistic view that the accident was the doomed fate of traffic to the certainty that problems of road safety can be overcome by preventive and punitive actions. Finally, road security appears as an "absolute social phenomenon". Any accident brutally unveils living conditions as well as social and professional inequalities between road users. It is also an indicator of social values. Furthermore, road security has become an instrument of political pressure for a few years now

The present thesis is conducted in the frame of a research project involving the ‘von Karman Institute (VKI Belgium)’ and the ‘Ecole des mines d’Alès (EMA France) with the support of the CEA Gramat. This project is about theoretical study, experimental characterization and modeling of hazards from pressurized or atmospheric reservoirs, containing liquids, flammable or not.

The objective of this thesis is to study the apparition criteria and the consequences of an accident involving a container of pressure liquefied gas (BLEVE phenomenon) or liquid fuels (Boilover phenomenon). After a bibliographic research on the two phenomena, an experimental study in laboratory scale is conducted and from the results, the phenomena and their hazards are modeled. Small scale experiments are performed in the BABELs facility (Bleve And Boilover ExperimentaL setup) that consists of a cylindrical chamber of 2m diameter and 3m high, with round shape flanges, made out of steel with a rated pressure of 0.5 MPa. It has 3 series of 7 optical accesses, an entrance door, and an optional air venting system.

A Boilover is a violent ejection of fuel due to the vaporization of a water sublayer, resulting in an enormous fire enlargement and formation of fireball and ground fire. Small scale experiments with cylindrical reservoirs of 0.08 to 0.3m diameter in glass or metal, filled with a mixture of diesel and oil have been performed. Instrumentation of the measurements consists of thermocouples rake, Medtherm radiometers, load cell and CCD or high-speed camera with a fisheye. During the quasi-steady combustion prior the Boilover, the typical variables describing a pool fire like burning rate, flame size, puffing frequency and radiation can be predicted with semi-empirical correlations available in the literature. At Boilover onset, high speed visualizations in glass reservoir show that the growth of one big bubble leads to a boiling front that propagates radially all along the fuel-water interface, ejecting the upper fuel layer and leading to the increase of flame size. LS-PIV technique applied to high-speed camera images shows that the flame enlargement is directly linked to the velocity of the flame.

A BLEVE (or Boiling Liquid Expanding Vapour Explosion) is an explosion resulting from the catastrophic failure of a vessel containing a liquid at a temperature significantly above its boiling point at normal atmospheric pressure. Small scale experiments are performed with cylinders of 42g of propane, laid horizontally and heated from below by an electrical resistor. A groove of the reservoirs on the upper part allows better reproducibility of the rupture. High speed visualization and shadowgraphy are helping in visualizing the rupture and the content release. Thermocouples and PCB are also used to measure respectively the temperature and the blast wave overpressure. These experiments show that the fluid behavior during rupture differs with the size of the weakened part and therefore with the rupture pressure. The internal pressure measurement showed that the rupture pressure and temperature are supercritical, leading to the definition of a new type of BLEVE since there is no distinction between liquid and vapor phases prior rupture.

Doctorat en Sciences de l'ingénieur
info:eu-repo/semantics/nonPublished

Cette etude concerne l'acier 16mnd5 utilise comme materiau de cuve dans les reacteurs a eau pressurisee (rep). En situation d'accidents graves, cet acier a bas taux de carbone faiblement allie change d'etat microstructural. Differentes phases de caracteristiques mecaniques distinctes sont susceptibles de se former selon l'histoire thermique subie. Ce travail porte sur la phase austenitique stable a haute temperature et sur le vieillissement de l'etat de reception du materiau. Nous avons determine des courbes d'evolution de la taille de grain austenitique. Un modele de croissance du type trainage de solute semble le plus approprie pour decrire la cinetique de croissance observee. Le comportement en fluage a haute temperature de la phase austenitique est examine. Le modele propose par lasalmonie et strudel convient a la description de nos resultats experimentaux. Ce modele est base sur la montee des dislocations en presence de glissement aux joints de grains et permet de prendre en compte l'influence de la taille de grain observee experimentalement. Lors du vieillissement a 700c de l'acier 16mnd5 dans son etat de reception, un durcissement microstructural progressif est observe. Ce durcissement est lie a la formation et a la croissance de phases blanches durcissantes de morphologie allongee. L'evolution de la precipitation semble independante du phenomene de durcissement.

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Dissertacao (Mestrado)
IPEN/D
Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP

Lors d’une insertion accidentelle de réactivité dans un réacteur nucléaire expérimental, la puissance du cœur peut augmenter de manière exponentielle, avec un temps caractéristique allant de quelques millisecondes à quelques centaines de millisecondes. À cause des effets neutroniques et thermohydrauliques, le système peut atteindre les conditions de crise d’ébullition à même d’engendrer une réaction explosive. Bien que la crise d’ébullition ait été largement étudiée en conditions de chauffage stationnaires, ce n’est pas le cas pour les transitoires notamment de type excursions de puissance. Le but de ce travail est donc de comprendre et de prédire la crise d'ébullition sous l’effet d’un chauffage transitoire rapide de l'eau sous fortes sous-saturations à pression modérée. Des campagnes expérimentales ont été réalisées pour étudier la crise d’ébullition dans de telles conditions au moyen de vidéos et de thermographie IR hautement résolues en temps et en espace. L’analyse de ces données a permis de déterminer la dépendance du flux critique en transitoire rapide en fonction des différents paramètres d’intérêt (temps caractéristique d’excursion de puissance, vitesse d’écoulement, sous-saturation, pression, largeur du canal, longueur de chauffe). De plus, une analyse approfondie de ces données a permis de mettre en évidence les mécanismes sous-jacents à la crise d’ébullition dans ces conditions. En convection forcée et avec de fortes sous-saturations, les bulles générées en paroi présentent un comportement pulsant. Ce phénomène assure un transfert de chaleur efficace depuis la paroi vers le fluide environnant. Le déclenchement de la crise d’ébullition se produit lorsqu’une fine couche de fluide adjacente à la paroi atteint les conditions de saturation. Un modèle développé à partir de ces observations met en évidence deux paramètres adimensionnés utiles pour décrire la nature transitoire du processus ainsi que pour identifier le mode de refroidissement dominant. Grâce à la connaissance du flux critique en régime permanent, le modèle permet d’estimer de manière conservative le flux critique en fonction de la période d’excursion de puissance et du sous-refroidissement. Ce modèle est maintenant prêt à être implémenté dans des codes de simulation pour l’étude des transitoires accidentels
In case of a reactivity insertion accident in an experimental nuclear reactor, heat generation in the core can grow exponentially in time, with a power escalation period ranging from a few to a few hundreds of milliseconds. Due to neutronic and thermohydraulic effects, boiling crisis may arise, possibly leading to an explosive reaction. If the boiling Crisis has been widely investigated in steady-state conditions, this has not been the case for transient heat inputs. The aim of the present work is to understand and to predict the transient flow boiling crisis in the conditions of moderate pressure and high subcooling. To this end, an experimental campaign has been realized making use of space and time highly resolved videos and IR thermography covering a wide range of experimental parameters. The analysis of the massive amount of data produced by these experiments gives a better insight on the dependency of the transient Critical Heat Flux to the different parameters of interest (power escalation period, flow velocity, subcooling, pressure, channel width, heating length). Moreover, their fine analysis enables to highlight the underlying mechanisms. For conditions of forced flow and high subcooling, the bubbles generated at the wall present a pulsating behavior. This specific process leads to an efficient heat transfer from the wall to the neighboring fluid. Boiling crisis is stated to occur when a thin layer of liquid contacting the wall reaches the saturation temperature. Starting from these observations, a model is developed which brings to light two non-dimensional parameters useful to describe the transient nature of the process and the dominant cooling processes. With the knowledge of the steady-state CHF, the model permits to conservatively estimate the value of the Critical Heat Flux for any power escalation period and subcooling. This model is now ready for implementation into simulation codes to investigate nuclear accidental transients

Les contraintes physiologiques cérébrales rendent le cerveau humain vulnérable à l'hypoxie, qu’elle soit environnementale (haute altitude) ou en lien avec une pathologie hypoxémiante. Parmi ces pathologies, et en raison de sa forte prévalence dans la population générale, le syndrome d'apnées obstructives du sommeil (SAOS) est un modèle physiopathologique reconnu des effets délétères de l'hypoxie sur le cerveau. Les épisodes cycliques d'apnées et d'hypopnées survenant au cours du sommeil qui caractérisent le SAOS entraînent une hypoxie intermittente, une fragmentation du sommeil et des fluctuations de la pression intra-thoracique, tous trois facteurs déclenchant des mécanismes intermédiaires contribuant au développement de maladies cardio-métaboliques ainsi que des répercussions cérébrales (troubles cognitifs et accidents vasculaires cérébraux (AVC)). Ce travail de thèse explore la relation bidirectionnelle entre les syndromes d’apnées du sommeil (SAS) et le cerveau. Le premier axe se concentre sur les conséquences neurocognitives du SAOS au travers du contrôle de la marche. Les répercussions neurocognitives du SAOS sont à ce jour bien décrites et des troubles de la marche ont récemment été mis en évidence, avec une relation de type dose-réponse entre la gravité du SAOS et la sévérité des troubles de la marche. Il a ainsi été suggéré que la marche pouvait représenter un marqueur des répercussions cérébrales du SAOS. Les effets du traitement par pression positive continue (PPC) sur le contrôle de la marche ont été investigués au cours de ce travail de Thèse, avec des résultats contrastés. Dans une première étude prospective contrôlée, 8 semaines de traitement par PPC entraînaient une amélioration du contrôle de la marche chez des patients atteints de SAOS sévère (Baillieul et al., 2018, Plos One). Afin de valider ces résultats et d'étudier les corrélats neurophysiologiques du lien entre marche et SAOS, nous avons mené un essai contrôlé randomisé étudiant l'impact de 8 semaines de traitement par PPC comparativement à la Sham-PPC (Baillieul et al., 2020, Soumis). Contrairement à notre hypothèse, nous n'avons constaté aucune amélioration du contrôle de la marche dans le groupe PPC, résultat corroboré par l'absence d'impact de la PPC sur les déterminants du contrôle de la marche. Le deuxième axe est centré sur les répercussions cérébro-vasculaires des SAS. SAS et AVC sont deux pathologies graves et étroitement liées, le SAS pouvant être à la fois cause et conséquence potentielle des AVC. Le présent travail est axé sur l'identification des traits phénotypiques de SAS chez les patients post-AVC, afin d'en améliorer le diagnostic (Baillieul et al., en préparation). Le dépistage du SAS post-AVC est crucial en raison du risque élevé de morbi-mortalité et de conséquences fonctionnelles associées au SAS après AVC, mais il ne peut être effectif sans une identification plus précise des patients à risque de SAS. Le troisième axe a été conçu comme une perspective qui servira au développement du deuxième axe. Dans ce dernier axe, le potentiel de l'imagerie cérébrale et en particulier de l'imagerie par résonance magnétique pour développer des marqueurs de récupération et étudier les mécanismes physiopathologiques des déficiences liées aux AVC sont présentés, au travers de la marche et de son contrôle. Les corrélats neuronaux de la marche comme activité post-AVC sont mis en évidence, en utilisant une approche de type Voxel-based lesion-symptom mapping (Baillieul et al., 2019, Hum. Mov. Sci.). Les marqueurs d'imagerie basés sur l’utilisation du Diffusion tensor imaging pour prédire la récupération de la marche post-AVC sont également présentés (Soulard et al., 2019, Neurology). Ces travaux sur les marqueurs d'imagerie cérébrale de la récupération post-AVC serviront à développer des outils pour les recherches à venir sur les corrélats neuronaux des SAS post-AVC
The human brain is a perfect example of our dependence on oxygen. Brain physiological constraints render it vulnerable to hypoxia, such as encountered in environmental conditions (high altitude exposure) or pathological hypoxemic conditions. Among those pathological conditions, and due to its high prevalence in general population and the various levels of hypoxia resulting of the different degrees of severity of the pathology, obstructive sleep apnoea syndrome (OSAS) is a pathophysiological model of choice to investigate the detrimental effects of hypoxia on the brain. The cyclical, repeated episodes of apnoea and hypopnea during sleep that characterize OSAS result in intermittent hypoxia, sleep fragmentation and fluctuations in intrathoracic pressure, which are stressors that triggers mechanisms contributing to the initiation and progression of life-threatening cardiometabolic diseases, as well as several brain repercussions, such as cognitive impairment and stroke. This Thesis work explores the bidirectional relationship between sleep apnoea syndromes (SAS) and the brain. The first axis is focused on the neurocognitive consequences of OSAS through the lens of gait control. The neurocognitive signature of OSAS has been thoroughly investigated but recently, gait impairments have been highlighted in severe OSAS, with dose-response relationship between OSAS severity and the magnitude of gait impairments. As gait control relies at least partly on frontal lobe functions, it has been suggested that gait could represent a marker of OSAS brain repercussions. We investigated the effects of continuous positive airway pressure (CPAP) treatment on gait control, with contrasting results. In a first prospective controlled study, eight weeks of CPAP improved gait control in severe OSAS patients (Baillieul et al., 2018, Plos One). In order to validate those results and investigate the neurophysiological correlates of the link between gait control and OSAS, we conducted a randomized controlled trial which investigated the impact of an 8-week CPAP treatment compared to sham-CPAP on gait control in severe OSAS patients (Baillieul et al., 2020, Submitted). Contrary to our hypothesis, we found no improvement in gait control in the CPAP group and this result is substantiated by the absence of impact of CPAP on the determinants of gait control, further illustrating the complexity of the OSAS-neurocognitive relationship. The second axis is focused on the cerebrovascular repercussions of SAS. SAS and stroke are both severe intertwined conditions, SAS being both cause and potentially consequence of stroke. The present work is focused on the identification of phenotypic traits of SAS in post-stroke patients, to improve diagnosis of SAS following stroke (Baillieul et al., in preparation). Screening stroke patients for SAS is crucial due to the high risk of morbimortality and functional consequences associated to SAS following stroke but cannot be achieved without a more accurate identification of patients at risk to develop SAS following stroke. The third axis has been conceived as a perspective that will serve the development of the second axis. In this last axis, the potential of brain imagery and in particular magnetic resonance imagery to develop markers of stroke recovery as well as investigate the pathophysiological mechanisms underlying stroke-related deficiencies are presented, with a specific focus on gait and walking activity. The neural correlates of walking activity following stroke are highlighted, using a voxel-based lesion-symptom mapping approach (Baillieul et al., 2019, Hum. Mov. Sci.). Imagery markers of walking recovery following stroke using diffusion tensor imaging are also presented (Soulard et al. 2019, Neurology). This work on brain imagery markers of stroke recovery will further serve the development of investigations focused on the neural correlates of SAS following stroke

Für den zielgerichteten Einsatz von präventiven und mitigativen Notfallmaßnahmen sowie zur Beurteilung ihrer Wirksamkeit während auslegungsüberschreitender Unfälle in Druckwasserreaktoren aber auch für Hinweise zum Störfallverlauf und für die Abschätzung der Auswirkungen auf die Anlagenumgebung müssen geeignete Störfallinstrumentierungen vorhanden sein. Insbesondere der Zustand des Reaktordruckbehälterinventars (RDB-Inventar) während der In-Vessel-Phase eines auslegungsüberschreitenden Unfalls lässt sich mit aktuellen Störfallinstrumentierungen nur stark eingeschränkt überwachen, wodurch die o. g. Forderungen nicht erfüllt werden können. Die vorliegende Arbeit beinhaltet detaillierte Untersuchungen für die Entwicklung einer Störfallinstrumentierung, welche eine durchgängige Zustandsüberwachung des RDB-Inventars während der In-Vessel-Phase eines auslegungsüberschreitenden Unfalls ermöglicht. Die Störfallinstrumentierung basiert auf der Messung und Klassifikation von unterschiedlichen Gammaflussverteilungen, welche während der In-Vessel-Phase außerhalb des Reaktordruckbehälters auftreten können. Ausgehend von der Analyse zum Stand von Wissenschaft und Technik wird der modell-basierte Ansatz für Structural Health Monitoring-Systeme genutzt, um eine grundlegende Vorgehensweise für die Entwicklung der Störfallinstrumentierung zu erarbeiten. Anschließend erfolgt eine detaillierte Analyse zu den Vorgängen während der In-Vessel-Phase und eine daraus abgeleitete Definition von Kernzuständen für einen generischen Kernschmelzunfall. Für die definierten Kernzustände werden mittels Simulationen (Monte-Carlo-Simulationen zum Gammastrahlungstransport in einem zu dieser Arbeit parallel laufenden Vorhaben) Gammaflüsse außerhalb des Reaktordruckbehälters berechnet. Die Simulationsergebnisse dienen dem Aufbau von Datenbasen für die Entwicklung und Analyse eines Modells zur Klassifikation von Gammaflussverteilungen. Für die Entwicklung des Klassifikationsmodells kommen drei diversitäre und unabhängig arbeitende Klassifikationsverfahren (Entscheidungsbaum, k-nächste-Nachbarn-Klassifikation, Multilayer Perzeptron) zur Anwendung, um die Identifikationsgenauigkeit und Robustheit der Störfallinstrumentierung zu erhöhen. Die abschließenden Betrachtungen umfassen die Validierung der Störfallinstrumentierung mittels eines Versuchstandes zur Erzeugung unterschiedlicher Gammaflussverteilungen. Im Ergebnis der Untersuchungen konnte die prinzipielle Funktionsweise der entwickelten Störfallinstrumentierung nachgewiesen werden. Unter der Voraussetzung, die Gültigkeit der definierten Kernzustände zu untermauern sowie weitere, nicht in dieser Arbeit betrachtete Kernschmelzszenarien mit in die Entwicklung der Störfallinstrumentierung einzubeziehen, steht somit insbesondere für zukünftige Kernkraftwerke mit Druckwasserreaktoren eine Möglichkeit für die messtechnische Überwachung des RDB-Inventars während auslegungsüberschreitender Unfälle bereit. Die Arbeit leistet einen wesentlichen Beitrag auf dem Gebiet der Reaktorsicherheitsforschung sowie für den sicheren Betrieb von kerntechnischen Anlagen.

In the event of hypothetical accident scenarios in PWR, emergency strategies have to be mapped out, in order to guarantee the reliable removal of decay heat from the reactor core, also in case of component breakdown. One essential passive heat removal mechanism is the reflux condensation cooling mode. This mode can appear for instance during a small break loss-of-coolant-accident (LOCA) or because of loss of residual heat removal (RHR) system during mid loop operation at plant outage after the reactor shutdown. In the scenario of a loss-of-coolant-accident (LOCA), which is caused by the leakage at any location in the primary circuit, it is considered that the reactor will be depressurized and vaporization will take place, thereby creating steam in the PWR primary side. Should this lead to ¿reflux condensation¿, which may be a favorable event progression, the generated steam will flow to the steam generator through the hot leg. This steam will condense in the steam generator and the condensate will flow back through the hot leg to the reactor, resulting in counter-current steam/water flow. In some scenarios, the success of core cooling depends on the behaviour of this counter-current flow. Over several decades, a number of experimental and theoretical studies of counter-current gas¿liquid two-phase flow have been carried out to understand the fundamental aspect of the flooding mechanism and to prove practical knowledge for the safety design of nuclear reactors. Starting from the pioneering paper of Wallis (1961), extensive CCFL data have been accumulated from experimental studies dealing with a diverse array of conditions A one-dimensional two field model was developed in order to predict the counter-current steam and liquid flow that results under certain conditions in the cold leg of a PWR when a SBLOCA (small break loss of coolant accident) in the hot leg is produced. The counter-current model that has been developed can predict the pressure, temperature, velocity profiles for both phases, also by taking into account the HPI injection system in the cold leg under a counter-current flow scenario in the cold leg. This computer code predicts this scenario by solving the mass, momentum and energy conservation equations for the liquid and for the steam separately, and linking them by using the interfacial and at the steam wall condensation and heat transfer, and the interfacial friction as the closure relations. The convective terms which appear in the discretization of the mass and energy conservation equations, were evaluated using the ULTIMATE-SOU (second order upwinding) method. For the momentum equation convective terms the ULTIMATE-QUICKEST method was used. The steam-water counter-current developed code has been validated using some experimental data extracted from some previously published articles about the direct condensation phenomenon for stratified two-phase flow and experimental data from the LAOKOON experimental facility at the Technical University of Munich.
Romero Hamers, A. (2014). STUDY OF THE THERMAL STRATIFICATION IN PWR REACTORS AND THE PTS (PRESSURIZED THERMAL SHOCK) PHENOMENON [Tesis doctoral]. Editorial Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/36536
Alfresco

Le suivi longitudinal individuel, dont l'objectif est de suivre l'évolution de l'état d'un individu au cours du temps, est au cœur de nombreuses problématiques de santé publique, particulièrement dans le domaine de la prévention médicale. L'accès croissant à des capteurs non invasifs permettant de mesurer divers bio-signaux (glycémie, fréquence cardiaque, mouvements des yeux, etc.) a encouragé la quantification de la physiologie, de la sensorimotricité ou du comportement humain dans le but de construire des marqueurs pour le suivi individuel. Cet objectif soulève toutefois plusieurs difficultés liées à la modélisation des signaux. Ce type particulier de données est en effet complexe à interpréter tel quel, et, a fortiori, à comparer au cours du temps. Dans cette thèse nous étudions la question de la représentation interprétable des bio-signaux pour le suivi longitudinal à travers la problématique du suivi de l'équilibre en consultation médicale. Cette problématique a des implications déterminantes dans la prévention des chutes et de la fragilité chez les personnes âgées. Nous nous focalisons en particulier sur l'utilisation des plateformes de force, qui sont communément utilisées pour enregistrer des mesures de posturographie, et peuvent être facilement déployées dans le contexte clinique grâce au développement de plateformes peu onéreuses comme la Wii Balance Board. Pour cette application particulière, nous étudions les avantages et les inconvénients de l'utilisation de méthodes d'extraction de caractéristiques ou de la recherche d'un modèle génératif des trajectoires. Nos contributions incluent premièrement la revue et l'étude d'un large ensemble de variables qui sont utilisées pour évaluer le risque de chute chez les personnes âgées, dérivées de la trajectoire du centre de pression (CoP). Ce signal est couramment analysé dans la littérature clinique pour inférer des informations sur le contrôle de l'équilibre. Ensuite, nous développons un nouveau modèle génératif, "Total Recall", basé sur un précédent modèle stochastique du CoP, qui s'est avéré reproduire plusieurs caractéristiques des trajectoires mais n'intègre pas la dynamique entre le CoP et le centre de masse (CoM) -- une dynamique considérée centrale dans le contrôle moteur de la posture. Par ailleurs, la comparaison des méthodes fréquemment utilisées pour l'estimation du CoM en équilibre statique debout permet de conclure qu'il est possible d'obtenir une estimation précise avec la Wii Balance Board. Les résultats montrent la pertinence potentielle du modèle Total Recall pour le suivi longitudinal du contrôle postural dans un contexte clinique. Dans l'ensemble, nous soulignons l'avantage d'utiliser des modèles génératifs, tout en mettant en évidence la complémentarité des deux approches, extraction de caractéristiques et modèles génératifs. En outre, cette thèse s'intéresse à l'apprentissage de représentations sur des données labellisées et adaptées à un objectif particulier de suivi. Nous introduisons de nouveaux algorithmes de classification qui tirent avantage des connaissances a priori pour améliorer les performances tout en conservant une interprétabilité complète. Notre approche s'appuie sur des algorithmes intrinsèquement interprétables et une régularisation sur l'espace des modèles basée sur des heuristiques médicales. Cette méthode est appliquée à la quantification du risque de chute et de la fragilité. Cette thèse défend l'importance de la recherche de méthodes interprétables, conçues pour des applications spécifiques et intégrant des a-priori fondés sur des connaissances expertes. Ces approches montrent des résultats positifs pour l'intégration des bio-signaux sélectionnés et de méthodes d'apprentissage statistique dans le cadre du suivi longitudinal du contrôle postural
Individual longitudinal follow-up, which aims at following the evolution of an individual state in time, is at the heart of numerous public health issues, particularly in the field of medical prevention. The increasing availability of non-invasive sensors that record various biosignals (e.g., blood glucose, heart rate, eye movements), has encouraged the quantification of human physiology, sensorimotricity, or behavior with the purpose of deriving markers for individual follow-up. This objective raises however several challenges related to signal modelling. Indeed, this particular type of data is complex to interpret, and, a fortiori, to compare across time. This thesis studies the issue of extracting interpretable representations from biosignals through the problematic of balance control follow-up in medical consultation, which has crucial implications for the prevention of falls and frailty in older adults. We focus in particular on the use of force platforms, which are commonly used to record posturography measures, and can be easily deployed in the clinical setting thanks to the development of low cost platforms such as the Wii Balance Board. For this particular application, we investigate the pros and cons of using feature extraction methods or alternatively searching for a generative model of the trajectories. Our contributions include first the review and study of a wide range of state-of-the-art variables that are used to assess fall risk in older adults, derived from the center of pressure (CoP) trajectory. This signal is commonly analyzed in the clinical literature to infer information about balance control. Secondly, we develop a new generative model, ``Total Recall'', based on a previous stochastic model of the CoP, which has shown to reproduce several characteristics of the trajectories but does not integrate the dynamic between the CoP and the center of mass (CoM) -- a dynamic which is considered to be central in postural control. We also review and compare the main methods of estimation of the CoM in quiet standing and conclude that it is possible to obtain an accurate estimation using the Wii Balance Board. The results show the potential relevance of the Total Recall model for the longitudinal follow-up of postural control in a clinical setting. Overall, we highlight the benefit of using generative models, while pointing out the complementarity of features-based and generative-based approachs. Furthermore, this thesis is interested in introducing representations learned on labeled data and tailored for a particular objective of follow-up. We propose new classification algorithms that take advantage of a priori knowledge to improve performances while maintaining complete interpretability. Our approach relies on bagging-based algorithms that are intrinsically interpretable, and a model-space regularization based on medical heuristics. The method is applied to the quantification of fall risk and frailty. This dissertation argues for the importance of researching interpretable methods, designed for specific applications, and incorporating a-priori based on expert knowledge. This approach shows positive results for the integration of the selected biosignals and statistical learning methods in the longitudinal follow-up of postural control. The results encourage the continuation of this work, the further development of the methods, especially in the context of other types of follow-up such as continuous monitoring, and the extension to the study of new biosignals

碩士
國立中正大學
犯罪防治碩士在職專班
105
Road traffic accident handling is highly professional and complex work, the supervision of the state in 91 year and 102 year for the road traffic accident related business to correct the case. The current police agencies have been responsible for traffic accident handling units and personnel, however, in the case of traffic accidents and the number of casualties in recent years continue to surge in the circumstances, responsible for road traffic accident handling police workload, work pressure and job burnout is becoming increasingly important attention. The main purpose of this study is: 1、To explore the different basic characteristics of the traffic accident handling police officers, the work of the feelings of the situation. 2、Explore the relevant circumstances of the traffic pressure and the coping strategies of police officers responsible for traffic accidents. 3、To study the basic characteristics of the traffic accident handling police officers, the impact of work pressure on the response strategy and forecast. 4、To construct a forecasting model that affects the traffic pressure handling of police officers, and to propose specific and constructive immediate and feasible long-term recommendations for the management of the police authorities. There are few studies on the work pressure and response strategy of the police officers involved in the road traffic accident handling. At present, this paper summarizes the work pressure and response strategy of the police officers responsible for traffic accident handling, Taichung Government Police Bureau for traffic accident handling police officers, the implementation of the questionnaire, after the pre-test subjects 27 copies, a total of 340 questionnaires issued, after the withdrawal of invalid questionnaires, fill incomplete and dishonesty respondents, completely there were 294 effective questionnaires, the effective recovery rate was 86.47%. And then the data collected by the statistical program SPSS data processing and analysis, and the number of times and percentage, one-way anova, t-test, pearson product-moment correlation, multi-regression analysis and other methods to analyze the results are as follows: 1、Different "marital status" and "police from the police" dedicated traffic accident handling police officers feel the pressure on the work of a significant level. 2、Different "average monthly handling of the number of accidents" dedicated traffic accident handling police officers on the application of the strategy to achieve significant standards. 3、The greater the pressure on police officers to deal with road traffic accidents, the greater the pressure to deal with the problem of "direct problem solving", "logical analysis and handling" and "emotional depression". Will use the "emotional adjustment to adapt" and "seek support from all parties" and other strategies to respond. 4、The "basic characteristics of the individual" have a significant impact on the overall "work stress" scale, which has a correlation between "personal basic characteristics" and "work stress", that is, the ability to predict between "personal basic characteristics" and "work stress".Which is better equipped with different "police education", "handling of A1 accident experience" and "service area" for "work pressure". 5、The "Work Stress" scale significantly affects the overall "response strategy" scale to verify that there is a correlation between "work stress" and "response strategy", that is, between "work stress" and "response strategy".The best use of the "work factor" and "organizational factors" for the "response strategy". Finally, according to the above analysis results, put forward relevant research proposals for working pressure and response strategies and follow-up research recommendations.

碩士
臺北城市科技大學
機電整合研究所
104
As automotive technology has been developing rapidly, customers have more and more demands on vehicles nowadays. Casting huge funds in research and development, many automobile companies pay a lot of attention on the vehicle safety control system. In order to raise driving speed, lower fuel consumption, diminish exhaust and enhance handling, vehicle safety and handling performance are highly demanded. Driving speed is raised because vehicle performance and the stability of suspension system are enhanced. It is pretty easy to speed up to one hundred kilometer per hour by stepping on the accelerator slightly. Therefore, in addition to improve handling performance, a relatively important unit for safety control is the tire, that is in contact with the ground. It is crucial to maintain tires in good condition all the time. In view to high accident rates for cars in Taiwan, inadequate maintenance is usually an important factor. Accident rates those result from tires are especially high because drivers disregard the maintenance knowledge, or do not have enough defensive tools for tire pressure detection, so that, pressure and temperature changes inside tires are not detected in time. According to the National Freeway Bureau’s statistics, 70% of the major accidents arise from tire puncture. Among those major accidents recently, 30% of those are classified as tire problems; and 75% of the problems are owing to tire leaking or insufficient tire pressure. This thesis studies an important issue about traffic safety in Taiwan presently, that is, the acknowledgement of using tires safely and tire pressure detectors. Whether the government propagates and carries out policies for tire puncture safety sufficiently and whether safety equipment installation in cars promotes effectively are indispensable and extremely important for life safety of all road users, which include drivers and pedestrians. In order to understand integrative requirements of defensive tire pressure detectors for market end-users, this study is performed by means of questionnaires. This research offers references to car users for preventing from accidents, which may result from neglected maintenance, or delay of replacing or installing defensive tire detectors due to price consideration. Consumers can realize and weigh between value and price. By collecting 47 SPSS questionnaires, which are focused on consumers who are considering and possibly going to replace tires and tire pressure detectors, this research confirms matters those consumers think over before transaction. Besides, 121 questionnaires of the AHP predicting mode are issued to drivers who have visited the service centers. Moreover, 142 questionnaires are issued and studied through the web. All data, being analyzed and verified, are offered to the service centers belongs for elaborating sale techniques, which can be used to help customers to decide the replacement or installation and to reduce accidents.

At Oregon State University the Multi-Application Small Light Water Reactor (MASLWR) integral effects testing facility is being prepared for safety analysis matrix testing in support of the NuScale Power Inc. (NSP) design certification progress. The facility will be used to simulate design basis accident performance of the reactor's safety systems. The design includes an initially evacuated, high pressure capable containment system simulated by a 5 meter tall pressure vessel. The convection-condensation process that occurs during use of the Emergency Core Cooling System has been characterized during two experimental continuous blowdown events. Experimental data has been used to calculate an average heat transfer coefficient for the containment system. The capability of the containment system has been analytically proven to be a conservative estimate of the full scale reactor system.
Graduation date: 2013

Orientação: Paulo Sousa; co-orientação: Ana Bernardo
Os eventos adversos, cuja taxa ronda 10%, são um problema de saúde pública que devem ser analisados e controlados. Os objetivos do estudo são caracterizar e avaliar o impacte dos Eventos Adversos numa unidade privada de cuidados continuados de convalescença, nomeadamente, Infeções Associadas a cuidados de Saúde, quedas e Úlceras por Pressão, ocorridos em 2012. Tratou-se de um estudo quantitativo, observacional, transversal, analítico e retrospetivo. A frequência dos EA’s foi de 44%. As IACS foram os mais frequentes (70%), na maioria infeções urinárias, os antibióticos foram prescritos sobretudo de forma empírica. As quedas representam 24% dos EA’s, ocorreram maioritariamente no quarto e WC, e sem lesões em 68% dos casos. As UP foram apenas 6% dos EA’s, localizavam-se principalmente nos calcanhares e região sagrada, e à data da alta estavam cicatrizadas ou melhoradas. As consequências de um EA foram moderadas em 78% dos casos e grave em apenas 3%. Os custos com material e medicação para tratamento de um EA foram mais elevados nas UP, contudo o tratamento das IACS consumiu mais recursos. Os doentes que sofreram EA’s tiveram mais dias de internamento do que os doentes que não sofreram EA’s, contudo não foi possível apurar os dias específicos de internamento por EA.
Public health adverse events are a problem whose rate is around 10% that shoul d be analyzed and controlled. The aim of this study is to characterize and evaluate the impact of adverse events on a private continuous care unit associated to health care infections, falls, pressure ulcers occurred in 2012. This study was quantitative, o bservational, transversal, analytical and retrospective. The frequency of adverse events are 44%, of these 70% were associated to health care infections, the majority where urinary infections, treated with empirical prescribed antibiotics. Patients falls r epresented 24% of all adverse events which occurred mostly in their rooms or bathrooms 68% of times without lesions. Only 6% of adverse events were pressure ulcers primarily localized on the heal or sacral region, by the time of hospital discharge were hea led or in better condition. 78% of cases the consequence were moderate only 3 % were serious. The cost of materials and medications to treat adverse events were highest for pressure ulcers, but health care associated infections consumed more resources. Pa tients that suffered adverse events had more days of hospitalization than patients without adverse events, it was not possible to verify specific days of hospitalization of adverse events.

Für den zielgerichteten Einsatz von präventiven und mitigativen Notfallmaßnahmen sowie zur Beurteilung ihrer Wirksamkeit während auslegungsüberschreitender Unfälle in Druckwasserreaktoren aber auch für Hinweise zum Störfallverlauf und für die Abschätzung der Auswirkungen auf die Anlagenumgebung müssen geeignete Störfallinstrumentierungen vorhanden sein. Insbesondere der Zustand des Reaktordruckbehälterinventars (RDB-Inventar) während der In-Vessel-Phase eines auslegungsüberschreitenden Unfalls lässt sich mit aktuellen Störfallinstrumentierungen nur stark eingeschränkt überwachen, wodurch die o. g. Forderungen nicht erfüllt werden können. Die vorliegende Arbeit beinhaltet detaillierte Untersuchungen für die Entwicklung einer Störfallinstrumentierung, welche eine durchgängige Zustandsüberwachung des RDB-Inventars während der In-Vessel-Phase eines auslegungsüberschreitenden Unfalls ermöglicht. Die Störfallinstrumentierung basiert auf der Messung und Klassifikation von unterschiedlichen Gammaflussverteilungen, welche während der In-Vessel-Phase außerhalb des Reaktordruckbehälters auftreten können. Ausgehend von der Analyse zum Stand von Wissenschaft und Technik wird der modell-basierte Ansatz für Structural Health Monitoring-Systeme genutzt, um eine grundlegende Vorgehensweise für die Entwicklung der Störfallinstrumentierung zu erarbeiten. Anschließend erfolgt eine detaillierte Analyse zu den Vorgängen während der In-Vessel-Phase und eine daraus abgeleitete Definition von Kernzuständen für einen generischen Kernschmelzunfall. Für die definierten Kernzustände werden mittels Simulationen (Monte-Carlo-Simulationen zum Gammastrahlungstransport in einem zu dieser Arbeit parallel laufenden Vorhaben) Gammaflüsse außerhalb des Reaktordruckbehälters berechnet. Die Simulationsergebnisse dienen dem Aufbau von Datenbasen für die Entwicklung und Analyse eines Modells zur Klassifikation von Gammaflussverteilungen. Für die Entwicklung des Klassifikationsmodells kommen drei diversitäre und unabhängig arbeitende Klassifikationsverfahren (Entscheidungsbaum, k-nächste-Nachbarn-Klassifikation, Multilayer Perzeptron) zur Anwendung, um die Identifikationsgenauigkeit und Robustheit der Störfallinstrumentierung zu erhöhen. Die abschließenden Betrachtungen umfassen die Validierung der Störfallinstrumentierung mittels eines Versuchstandes zur Erzeugung unterschiedlicher Gammaflussverteilungen. Im Ergebnis der Untersuchungen konnte die prinzipielle Funktionsweise der entwickelten Störfallinstrumentierung nachgewiesen werden. Unter der Voraussetzung, die Gültigkeit der definierten Kernzustände zu untermauern sowie weitere, nicht in dieser Arbeit betrachtete Kernschmelzszenarien mit in die Entwicklung der Störfallinstrumentierung einzubeziehen, steht somit insbesondere für zukünftige Kernkraftwerke mit Druckwasserreaktoren eine Möglichkeit für die messtechnische Überwachung des RDB-Inventars während auslegungsüberschreitender Unfälle bereit. Die Arbeit leistet einen wesentlichen Beitrag auf dem Gebiet der Reaktorsicherheitsforschung sowie für den sicheren Betrieb von kerntechnischen Anlagen.:1 Einleitung 2 Analyse zum Stand von Wissenschaft und Technik 2.1 Sicherheit in deutschen Kernkraftwerken mit Druckwasserreaktor 2.1.1 Mehrstufenkonzept 2.1.2 Störfallinstrumentierungen 2.2 Auslegungsüberschreitende Unfälle mit Kernschmelze in DWR 2.2.1 Auslösende Ereignisse 2.2.2 Grundlegender Ablauf eines auslegungsüberschreitenden Unfall mit Kernschmelze 2.3 Strahlungstechnik, Strahlungsmesstechnik 2.3.1 Grundlagen der Strahlungstechnik 2.3.2 Wechselwirkungen von Gammastrahlung mit Materie 2.3.3 Messung ionisierender Strahlung 2.4 Verfahren und Methoden der Zustandsüberwachung 2.4.1 Zustandsüberwachung 2.4.2 Structural Health Monitoring 2.4.3 Mustererkennung 2.4.4 Entscheidungsbäume 2.4.5 k-nächste-Nachbarn-Klassifikation 2.4.6 Künstliche neuronale Netze 2.5 Schlussfolgerungen aus der Analyse zum Stand von Wissenschaft und Technik 2.5.1 Zusammenfassung zum Kapitel 2 2.5.2 Zielstellung, Aufbau und Abgrenzung der Arbeit 3 Analyse der In-Vessel-Phase und Definition von Kernzuständen 3.1 Detaillierte Analyse der In-Vessel-Phase 3.1.1 Auftretende Temperaturbereiche 3.1.2 Vorgänge während der frühen In-Vessel-Phase 3.1.3 Vorgänge während der späten In-Vessel-Phase 3.1.4 Spaltproduktfreisetzung 3.2 Definition von Kernzuständen für einen generischen Kernschmelzunfall 3.3 Zusammenfassung zum Kapitel 3 4 Datenbasen zur Entwicklung und Analyse des Klassifikationsmodells 4.1 Beschreibung der Monte-Carlo-Simulationsmodell 4.2 Beschreibung der Simulationsergebnisse und Merkmalsextraktion 4.3 Datenbasis zur Entwicklung 4.4 Datenbasen zur Analyse 4.5 Zusammenfassung zum Kapitel 4 5 Entwicklung und Analyse des Klassifikationsmodells 5.1 Beschreibung des Klassifikationsmodells 5.2 Teilmodell 1 - Entscheidungsbaum 5.2.1 Entwicklung 5.2.2 Analyse der Identifikationsgenauigkeit 5.3 Teilmodell 3 - k-nächste-Nachbarn-Klassifikation 5.3.1 Entwicklung 5.3.2 Analyse der Identifikationsgenauigkeit 5.4 Teilmodell 3 - Multilayer Perzeptron 5.4.1 Trainings- und Testdatenbasis 5.4.2 Entwicklung 5.4.3 Analyse der Identifikationsgenauigkeit 5.5 Teilmodell 4 - Vergleichsalgorithmus 5.5.1 Entwicklung 5.5.2 Analyse der Identifikationsgenauigkeit 5.6 Analysen zur Robustheit des Klassifikationsmodells 5.6.1 Ausfall einzelner Gammastrahlungsdetektoren 5.6.2 Gleichzeitiger Ausfall mehrerer Gammastrahlungsdetektoren 5.7 Zusammenfassung und Schlussfolgerungen für das Kapitel 5 6 Validierung der Kernzustandsüberwachungsverfahren 6.1 Zielstellung und Vorgehensweise 6.2 Versuchstand zur Validierung 6.2.1 Aufbau 6.2.2 Funktionsweise 6.3 Anpassung der Kernzustandsüberwachungsverfahren an den Versuchsstand 6.4 Validierungsexperimente 6.4.1 Experiment 1 - Füllstandsänderungen 6.4.2 Experiment 2 - Quellenbewegungen 6.4.3 Experiment 3 - Füllstandsänderungen, Quellenbewegungen und Änderung von Profilkonturen 6.5 Zusammenfassung und Schlussfolgerungen für das Kapitel 6 7 Zusammenfassung und Ausblick

This work seeks to illustrate the potential benefits afforded by implementing aspects of fluid dynamics, especially the latest computational fluid dynamics (CFD) modeling approach, through numerical experimentation and the traditional discipline of physical experimentation to improve the calibration of the severe reactor accident analysis code, MELCOR, in one of several spent fuel pool (SFP) complete loss-of-coolant accident (LOCA) scenarios. While the scope of experimental work performed by Sandia National Laboratories (SNL) extends well beyond that which is reasonably addressed by our allotted resources and computational time in accordance with initial project allocations to complete the report, these simulated case trials produced a significant array of supplementary high-fidelity solutions and hydraulic flow-field data in support of SNL research objectives. Results contained herein show FLUENT CFD model representations of a 9x9 BWR fuel assembly in conditions corresponding to a complete loss-of-coolant accident scenario. In addition to the CFD model developments, a MATLAB based control-volume model was constructed to independently assess the 9x9 BWR fuel assembly under similar accident scenarios. The data produced from this work show that FLUENT CFD models are capable of resolving complex flow fields within a BWR fuel assembly in the realm of buoyancy-induced mass flow rates and that characteristic hydraulic parameters from such CFD simulations (or physical experiments) are reasonably employed in corresponding constitutive correlations for developing simplified numerical models of comparable solution accuracy.
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