Overheating in buildings is predicted to increase as a result of a warming climate and urbanisation in most cities. With regards to responding to this challenge, decision makers ranging from_ design teams, local authorities, building users, national programs and market innovators; and during the different stages of a building’s service life, want to know a few pertinent matters: What space characteristics and buildings are at a higher risk and by how much?; What are the tradeoffs between alternative design and/or user-based actions?; What are the likely or possible consequences of their decisions?; What is the impact of climate change to indoor overheating?; among other decision support questions. However, such decision appraisal information still remains buried and dispersed in existing simulation models, and empirical studies, and not yet been clearly articulated in any existing study or model. Especially decision support information articulated in a way that gives each decision maker maximum capacity to anticipate and respond to thermal discomfort in different spaces and through the lifetime of a building. There is a need for an integrated and systematic means of building adaptation decision-support, which provides analytical leverage to these listed decision makers. A means that: 1) assimilates a range of indoor thermal comfort's causal and solution space processes; 2) reveals and enhances the exploration of the space and time-dependent patterns created by the dynamics of the indoor overheating phenomenon through time; and one that 3) imparts insight into decision strategy and its synthesis across multiple decision makers. This study recognises the lack of an overarching framework attending to the listed concerns. Therefore, the key aim of this thesis is to develop and test a building adaptation decision-support framework, which extends the scope of existing frameworks and indoor overheating risk models to facilitate trans-sectional evaluations that reveal temporal decision strategies. The generic framework frames a multi-method analysis aiming to underpin decision appraisal for different spaces over a 50 to 100-year time horizon. It constitutes an underlying architecture that engages the dimensions of decision support information generation, information structuring, its exploration and dissemination, to ease in drawing decision strategy flexibly and transparently. The multi-method framework brings together: 1) Systems thinking methods to a) facilitate the systematic exposure of the elements that shape indoor overheating risk, and b) reveal the processes that shape multi-stakeholder decision-making response over time; 2) The use of normative, predictive and exploratory building scenarios to a) examine the overheating phenomenon over time, and b) as a lens through which to explore the micro-dynamics brought about by aspects of heterogeneity and uncertainty; and 3) The application of both computational and optimization techniques to appraise potential routes towards indoor thermal comfort over an extended time scale by a) tracking shifts in frequency, intensity and distribution of indoor overheating vulnerability by causal elements over time and space; and b) tracking shifting optima of the heat mitigation solution space, with respect to time, climate futures, heterogeneity of spaces, and due to thermal comfort assumptions. The framework’s potential has been demonstrated through its application to office buildings in Nairobi.

This study was based on the uncertainty and sensitivity analysis of a generic 10 MW Materials Test Reactor (MTR). In this study an uncertainty and sensitivity analysis methodology called code scaling applicability and uncertainty (CSAU) was implemented. Although this methodology follows 14 steps, only the following were carried out: scenario specification, nuclear power plant (NPP) selection, phenomena identification and ranking table (PIRT), selection of frozen code, provision of code documentation, determination of code applicability, determination of code and experiment accuracy, NPP sensitivity analysis calculations, combination of biases and uncertainties, and total uncertainty to calculate specific scenario in a specific NPP. The thermal hydraulic code Flownex®1 was used to model only the reactor core to investigate the effects of the input parameters on the selected output parameters of the hot channel in the core. These output parameters were mass flow rate, temperature of the coolant, outlet pressure, centreline temperature of the fuel and surface temperature of the cladding. The PIRT process was used in conjunction with the sensitivity analysis results in order to select the relevant input parameters that significantly influenced the selected output parameters. The input parameters that have the largest effect on the selected output parameters were found to be the coolant flow channel width between the plates in the hot channel, the width of the fuel plates itself in the hot channel, the heat generation in the fuel plate of the hot channel, the global mass flow rate, the global coolant inlet temperature, the coolant flow channel width between the plates in the cold channel, and the width of the fuel plates in the cold channel. The uncertainty of input parameters was then propagated in Flownex using the Monte Carlo based uncertainty analysis function. From these results, the corresponding probability density function (PDF) of each selected output parameter was constructed. These functions were found to follow a normal distribution. / MIng (Nuclear Engineering), North-West University, Potchefstroom Campus, 2014

Neapibrėžtumo analizė techninių sistemų modeliavimo rezultatams yra ypač aktuali, kai modeliuojamas pavojingų sistemų darbas, saugą užtikrinančių sistemų funkcionavimas, nagrinėjami avarijų scenarijai ar kiti, su rizika susiję klausimai. Tokiais atvejais, ypatingai reaktorių saugos analizės srityje, yra labai svarbu, kad gauti modeliavimo rezultatais būtų robastiški. Šiame darbe yra atliekama Ignalinos AE tikimybinio saugos vertinimo modelio neapibrėžtumo ir jautrumo analizė. Neapibrėžtumo ir jautrumo analizė atlikta naudojantis skirtingais statistinio vertinimo metodais, taikant programų paketą SUSA. Gauti rezultatai palyginti su tikimybinio modeliavimo sistemos Risk Spectrum PSA tyrimo rezultatais. Palyginimas parodė, jog skirtingais metodais ir programiniais paketais parametrų reikšmingumas įvertintas vienodai. Statistinė neapibrėžtumo ir jautrumo analizė, taikant Monte Karlo modeliavimo metodą, leido nustatyti parametrus turėjusius didžiausią įtaką modelio rezultatui. / The uncertainty estimation is the part of full analysis for modelling of safety system functioning in case of the accident, for risk estimation and for making the risk-based decision. In this paper the uncertainty and sensitivity analysis of Ignalina NPP probabilistic safety assessment model was performed using SUSA software package. The results were compared with the results, performed using software package Risk Spectrumm PSA. Statistical analysis of uncertainty and sensitivity allows to estimate the influence of parameters on the calculation results and find those modelling parameters that have the largest impact on the result. Conclusions about for importance of a parameters and sensitivity of the result are obtained using a linear approximation of the model under analysis.

Dėl spartaus technologijų naudojimo paskutiniais dešimtmečiais kuriama vis daugiau sudėtingų sistemų, kurių saugos užtikrinimui turi būti vertinamas techninės ir programinės įrangos patikimumas bei žmogaus-operatoriaus veiksmai. Analizuojant tokias sistemas ypatingai svarbią reikšmę turi laiko faktorius ir su juo susiję determinuoti fiziniai procesai bei stochastiniai įvykiai. Šio tiriamojo darbo tikslas yra sukurti tikimybinės dinamikos modeliavimo metodiką išplėtojant susijusias patikimumo analizės priemones bei jas pritaikyti realios sistemos tyrimui. Sprendžiant užsibrėžtus uždavinius, darbe buvo pritaikyta pažangi stimuliuojamos dinamikos teorija, kol kas neturinti plataus praktinių modelių pagrindimo. Pritaikyta imitacinio modeliavimo metodika suteikė galimybę atlikti visapusišką šilumnešio praradimo avarijos saugos analizę. Reikšmingiausi darbo rezultatai yra susiję su neapibrėžtų įvykių ir dinaminių sistemų saugos analize, siekiant padidinti jų patikimumą. Didžioji atlikto darbo taikymų dalis skirta techninėms dinaminėms sistemoms. Darbe išnagrinėti ir išplėtoti modeliavimo metodai, kurie yra tinkami tirti sistemų patikimumą, susijusį su uždelstais pavojingais įvykiais ar rizikingais operatorių sprendimais. / The current probabilistic safety analysis is not capable of estimating the reliability of the complex dynamic systems where the interactions occur between hardware, software and human actions. In the safety analysis of these systems the time factor is as much important as it joins an evolution of physical variables and stochastic events. In this master thesis the simulation and reliability analysis of the probabilistic dynamics are considered. The new approach of stimulus based probabilistic dynamics is used for the Monte Carlo simulations of the dynamic system. The developed methodology was applied for the safety analysis of the loss of the coolant accident in the nuclear reactor. Besides the assessment of the probability of system failure the scenario analysis was accomplished. The essential events were identified. The uncertainty and sensitivity analysis revealed that the failure probability had a wide range of the distribution due to the uncertainty of twelve simulation parameters. Four main parameters were identified as their uncertainty had the biggest correlation with the uncertainty of the system failure. For the complete reliability analysis the relations between the failure probability and the system characteristics were determined.

This study was based on the uncertainty and sensitivity analysis of a generic 10 MW Materials Test Reactor (MTR). In this study an uncertainty and sensitivity analysis methodology called code scaling applicability and uncertainty (CSAU) was implemented. Although this methodology follows 14 steps, only the following were carried out: scenario specification, nuclear power plant (NPP) selection, phenomena identification and ranking table (PIRT), selection of frozen code, provision of code documentation, determination of code applicability, determination of code and experiment accuracy, NPP sensitivity analysis calculations, combination of biases and uncertainties, and total uncertainty to calculate specific scenario in a specific NPP. The thermal hydraulic code Flownex®1 was used to model only the reactor core to investigate the effects of the input parameters on the selected output parameters of the hot channel in the core. These output parameters were mass flow rate, temperature of the coolant, outlet pressure, centreline temperature of the fuel and surface temperature of the cladding. The PIRT process was used in conjunction with the sensitivity analysis results in order to select the relevant input parameters that significantly influenced the selected output parameters. The input parameters that have the largest effect on the selected output parameters were found to be the coolant flow channel width between the plates in the hot channel, the width of the fuel plates itself in the hot channel, the heat generation in the fuel plate of the hot channel, the global mass flow rate, the global coolant inlet temperature, the coolant flow channel width between the plates in the cold channel, and the width of the fuel plates in the cold channel. The uncertainty of input parameters was then propagated in Flownex using the Monte Carlo based uncertainty analysis function. From these results, the corresponding probability density function (PDF) of each selected output parameter was constructed. These functions were found to follow a normal distribution. / MIng (Nuclear Engineering), North-West University, Potchefstroom Campus, 2014

Plus d'un million de personnes meurent dans des accidents sur les routes du monde et beaucoup de millions sont gravement blessés chaque année. Selon les études, ‘Run-Off-Road accidents (ROR)’, c'est-à-dire que le véhicule a au moins une collision avec des équipements routiers, représentent environ 10% des accidents routières, mais 45% de tous les accidents mortels sont des ROR. Les dispositifs de retenue des véhicules (DDR) sont les infrastructures installées sur la route pour fournir un niveau de confinement du véhicule ‘hors de contrôle’. La barrière de sécurité routière est un DDR continu installé à côté ou sur la réserve centrale d'une route pour empêcher les véhicules errants de s'écraser sur les obstacles routiers et de les conserver en toute sécurité. Les résultats statistique montrent que l'existence des barrières peut réduire les morts jusqu'à un facteur de 4 par rapport aux collisions contre d'autres obstacles routiers. Les performances de sauvetage d'un DDR dépendent de la conception de l'appareil. Des normes telles que EN1317 ont normalisé les conditions des essais de chocs sous lesquelles une conception de DDR doit être testée et ont défini les critères pour l'évaluation des performances d'une conception. En fait, un DDR ne puisse pas vraiment être optimisé: il existe des critères multiples pour l'évaluation de la performance d'un DDR et tous les critères ne peuvent pas être optimisés en même temps; les conditions de travail d’un DDR, c'est-à-dire les conditions d'impact d’un DDR avec un véhicule errant, sont nombreuses; les facteurs incertains du DDR peuvent dégrader les performances d'une conception. La thèse vise à définir une approche qui peut servir : l'analyse de sensibilité (AS) et la conception robuste du DDR ; enrichissement des normes existantes dans la conception du DDR. Le cas d'une barrière de sécurité routière est spécifié dans l'étude : une barrière a été testée expérimentalement, le programme Ls-Dyna est utilisé pour la simulation de choc de l'appareil ; en tenant compte des propriétés du modèle de choc, les efficacités de différentes méthodes de l’AS ont été étudiées ; les influences des facteurs critiques dont les incertitudes contribuent le plus à l'instabilité de la barrière ont été quantifiées avec les approches d’AS sélectionnées ; compte tenu des incertitudes des facteurs critiques, l’optimisation robuste de multi-objectif de la barrière est réalisée ; des simulations d'impact de la barrière optimisée ont été effectuées sous des conditions d'impact différentes pour évaluer ses performances dans les véritables accidents. Les approches présentées dans l'article peuvent être utiles pour la conception d'autres DDR ou plus largement d'autres systèmes d'ingénierie complexes. On peut espérer que l'analyse de robustesse et l'analyse de la généralisation (c'est-à-dire l'évaluation de la performance du DDR sous différentes conditions d'impact) du DDR pourraient enrichir les normes de la conception des DDR / More than 1 million people die in crashes on the world’s roads and many millions are seriously injured each year. According to the studies: Run-Off-Road accidents (ROR), i.e. the vehicle run-off the road into the roadside and has at least one collision with either roadside equipment or the roadside itself, “represent about 10% of the total road accidents, while 45% of all fatal accidents are ROR”. Vehicle Restraint Systems (VRS) are the infrastructures installed on the road to provide a level of containment for an errant vehicle. Safety barrier is “continuous VRS installed alongside, or on the central reserve, of a road to prevent errant vehicles from crashing on roadside obstacles, and to retain them safely”. Statistic results show that “the existence of protective barriers on road can reduce fatalities up to a factor of 4 when compared to collisions against other road obstacles.” The life-saving performances of a VRS depend on the design of the device. Standards such as EN1317 normalized the impact conditions under which a design of VRS must be tested by crash tests, and defined the criteria for performance evaluation of a design. While a VRS cannot really be optimized: Multi-criteria exist for performance evaluation of a VRS and all the criteria cannot be optimized in the same time; the impact conditions of the VRS with the errant vehicle are numerous; uncertain factors of the VRS may degrade the performances of a design. The thesis aims to define an approach that can serve: sensitivity analysis (SA) and robust design of the VRS; Enrichment for the existing standards in the design of VRS. The case of a safety barrier is specified in the study: a safety barrier has been test experimentally, the program Ls-Dyna was used for crash simulation of the device; considering properties of the crash model, efficiencies of different SA methods were studied and influences of the critical factors whose uncertainties contribute the most to the instability of the barrier were quantified with the selected SA approaches; considering the uncertainties of the critical factors, Multi-Objective robust optimization of the tested barrier were realized; under different impact conditions, crash simulations of the optimized barrier were carried out to evaluate its performances in the real crash accidents. The approaches presented in the article can be useful for the design of other VRS or more broadly, other complex engineering systems. Hopefully, the robustness analysis and generalization analysis (i.e. performance evaluation of the VRS under different impact conditions) of the safety barrier could enrich the standards for the design of VRS

Étant de plus en plus isolés, les bâtiments très performants sont très sensibles aux apports solaires transmis par les vitrages ainsi qu'aux apports internes. Dans ce contexte, l'inertie thermique peut être utile en stockant l'énergie excédentaire et en réduisant les variations de température, améliorant ainsi le confort thermique.Évaluer la performance énergétique, environnementale et le confort thermique des bâtiments nécessite des outils de simulation thermique dynamique (STD) fiables. Historiquement, les modélisateurs ont essayé de trouver un compromis approprié entre précision et efficacité. Des hypothèses simplificatrices ont alors été intégrées dans les outils STD et ont un lien étroit avec l'inertie thermique. La validité de telles hypothèses, notamment la globalisation des échanges convectifs et radiatifs GLO intérieurs, ou la distribution forfaitaire des apports solaires transmis par les vitrages nécessitent particulièrement d'être remises en questions dans le contexte des bâtiments très isolés.Ainsi, un modèle découplant les échanges convectifs et radiatifs GLO ainsi qu'un modèle de suivi de la tache solaire (modèles détaillés) ont été implémentés dans une plateforme de simulation mettant en œuvre l'analyse modale et une discrétisation par volumes finis.Une première comparaison entre les modèles détaillés et simplifiés a été réalisée sur des cas d'études du "BESTEST", intégrant aussi des résultats d'outils STD de référence au niveau international (EnergyPlus, ESP-r, TRNSYS). Un travail similaire a été réalisé sur le cas d'une maison passive instrumentée (plateforme INCAS à Chambéry) en utilisant des techniques d'analyses d'incertitudes et de sensibilité.Les résultats montrent qu'une tendance à la baisse concernant les besoins de chauffage et de refroidissement existe en ce qui concerne les modèles détaillés considérés ici. D'autre part, il semble que ces modèles détaillés ne contribuent pas à diminuer significativement les écarts entre les simulations et les mesures. / Being highly insulated, low energy buildings are very sensitive to variable solar and internal gains. In this context, thermal mass is useful by storing surplus energy and reducing temperature variation, thus improving thermal comfort.Assessing energy, environmental and thermal comfort performances requires reliable building dynamic thermal simulation (DTS) tools. Historically, model developers have tried to find a fair-trade between accuracy and simulation efficiency within a fit-to-purpose philosophy. Simplifying assumptions have therefore been integrated into DTS tools and have a close relation with thermal mass. The validity of such assumptions, for instance constant interior convective and infrared radiative superficial exchange coefficients, or fixed distribution of solar gains transmitted through windows, particularly need to be reassessed in the case of high performance buildings.A first comparison between detailed and simplified models has been performed according to the "BESTEST", integrating also international DTS reference tools (EnergyPlus, ESP-r, TRNSYS). Similar work, but using uncertainty and sensivitivity methods has been carried out using experimental measurements on a passive building (INCAS platform in Chambéry). The results show a trend for the detailed models studied here to estimate lower heating and cooling loads. Furthermore, it seems that these detailed models don't contribute to reduce significantly discrepancies between simulations and measurements.