Au cours d’un transitoire d’Accident de Perte de Réfrigérant Primaire (APRP), la vaporisation de l’eau dans la cuve d’un réacteur nucléaire conduit à l’assèchement et à l’augmentation de la température des crayons de combustible, à leur gonflement thermomécanique et à la rupture des gaines de ces crayons remplies de matériaux combustibles fragmentés. Ce gonflement peut être à l’origine d’un bouchage significatif d’une partie du coeur et compromettre ainsi son refroidissement lors de la phase de renoyage où l’eau injectée via les systèmes de sécurité pénètre dans le bas du coeur. Lors de cette phase de renoyage, la vaporisation importante de l’eau produit un fort débit de vapeur qui arrache et entraîne des gouttelettes dans les zones bouchées. L’enjeu de cette thèse est d’évaluer les capacités de refroidissement des crayons ballonnés par l’impact des gouttes d’eau. Pour ce faire, une étude expérimentale est réalisée au LEMTA de Nancy, afin de mesurer le flux de refroidissement d’un train de gouttes impactant une paroi chaude. L’influence des caractéristiques dynamiques des gouttes sur le flux échangé entre la goutte et la paroi est expérimentalement étudiée. Ces essais ont permis la réalisation d’une base de donnée permettant de valider un modèle de flux goutte/paroi Ce modèle d’échange goutte/paroi est réalisé à partir d’une modélisation des paramètres clefs gouvernant l’échange, à savoir, le diamètre d’étalement de la goutte sur la paroi, l’épaisseur de la couche de vapeur créée sous la goutte et le temps de séjour de la goutte sur la paroi. Ce modèle, validé expérimentalement, est intégré dans le code NEPTUNE_CFD dans le but de réaliser des simulations de refroidissement d’un assemblage de crayon, en phase de renoyage, en prenant en compte l’effet des gouttes impactantes / In a pressurized water reactor (PWR), during a Loss Of Coolant Accident (LOCA), liquid water evaporates and the fuel assemblies are not cooled anymore; as a consequence, the temperature rises to such an extent that some parts of the fuel assemblies can be deformed resulting in ’ballooned regions’. When reflooding occurs, the cooling of these partially blocked parts of the fuel assemblies will depend on the coolant flow that is a mixture of overheated vapour and undersaturated droplets. The aim of this thesis is to study the heat transfer between droplets and hot walls of the fuel rods. In this purpose, an experimental device has been designed in accordance with droplets and wall features (droplet velocity and diameter, wall temperature) representative of LOCA conditions. The cooling of a hot Nickel disk, previously heated by induction, is cooled down by a stream of monodispersed droplet. The rear face temperature profiles are measured by infrared thermography. Then, the estimation of wall heat flux is performed by an inverse conduction technique from these infrared images. The effect of droplet dynamical properties (diameter, velocity …) on the heat flux is studied. These experimental datas allow us to validate an analytical model of heat exchange between droplet and hot slab. This model is based on combined dynamical and thermal considerations. On the one hand, the droplet dynamics is considered through a spring analogy in order to evaluate the evolution of droplet features such as the spreading diameter when the droplet is squeezed over the hot surface. On the other hand, thermal parameters, such as the thickness of the vapour cushion beneath the droplet, are determined from an energy balance. In the short term, this model will be integrated in a CFD code (named NEPTUNE_CFD) to simulate the cooling of a reactor core during a LOCA, taking into account the droplet/wall heat exchange

Falls and collisions are the most common types of events leading to sports-related concussions where impacts to the head play an important role on the onset of traumatic brain injury. Each event can be described by impact parameters that define the loading conditions on the head and brain and are necessary for accurate accident reconstruction employing physical impact tests, anthropometric headforms, and finite element (FE) modelling. It was the purpose of this research to describe the effects and interactions of impact velocity, compliance, mass and impact location on head acceleration and brain tissue strain measures associated with risk of concussions in sports. Impact parameters were varied to capture responses from no-injury up to concussive levels. Study one examined the effect of impact parameters on fall events simulated using a monorail drop tower. Impact mass was varied using three different headforms representing child, adolescent, and adult sizes measuring peak linear and angular acceleration and maximum principal strain. Regression analysis revealed that impact compliance was the most influential on peak linear and angular acceleration measures, meanwhile FE strain was most affected by changes in impact velocity. Smaller headforms tend to produce higher acceleration and strain values, supporting the need for age and size related mechanical definitions of risk. Study two examined the effect of impact parameters for collision events simulated using a multi-mass pendulum to represent common striking masses in sport measuring peak linear and angular acceleration and strain. Study three provided further insight into collision impacts by evaluating the distribution of peak strains in different brain lobes and the volume of the brain experiencing strains passed a critical level. Results show that compliance was similarly the most influential on peak head acceleration whereas peak strain and volume were most affected by impact velocity. Mass-velocity interactions had effects where a 9 kg mass had greater response than 15 kg, but similar to 21 kg. The temporal lobe consistently contained the highest strains with the rear boss non-centric impact location producing the largest values. Interacting impact parameters illustrate the challenges with predicting associated risk of concussion from head collisions in sport and supports the need to identify effective performance ranges of protective materials.

Understanding the age and distribution of shallow ice on Mars is valuable for interpreting past and present climate conditions, and has implications on habitability and future in situ resource utilization. Many ice-related features, such as lobate debris aprons and concentric crater fill, have been studied using a range of remote sensing techniques. Here, I explore the distribution of expanded craters, a form of sublimation thermokarst where shallow, excess ice has been destabilized and sublimated following an impact event. This leads to the collapse of the overlying dry regolith to produce the appearance of diameter widening. The modern presence of these features suggests that excess ice has remained preserved in the terrain immediately surrounding the craters since the time of their formation in order to maintain the surface. High-resolution imagery is ideal for observing thermokarst features, and much of the work described here will utilize data from the Context Camera (CTX) and High Resolution Imaging Science Experiment (HiRISE) on the Mars Reconnaissance Orbiter (MRO). Expanded craters tend to be found in clusters that emanate radially from at least four primary craters in Arcadia Planitia, and are interpreted as secondary craters that formed nearly simultaneously with their primaries. Crater age dates of the primaries indicate that the expanded secondaries, as well as the ice layer into which they impacted, must be at least tens of millions of years old. Older double-layer ejecta craters in Arcadia Planitia commonly have expanded craters superposed on their ejecta – and they tend to be more expanded (with larger diameters) in the inner ejecta layer. This has implications on the formation mechanisms for craters with this unique ejecta morphology. Finally, I explore the distribution of expanded craters south of Arcadia Planitia and across the southern mid-latitudes, along with scalloped depressions (another form of sublimation thermokarst), in order to identify the modern excess ice boundary in this region and any longitudinal variations. This study identifies some potential low-latitude locations with patchy excess ice, possibly preserved during a past climate. Through these studies, I will infer regions that contain abundant ice today and consider the implications that this ice has on both the martian climate and future exploration.

More than a hundred hydropower dams have already been built in the Amazon basin and numerous proposals for further dam constructions are under consideration. The accumulated negative environmental effects of existing dams and proposed dams, if constructed, will trigger massive hydrophysical and biotic disturbances that will affect the Amazon basin's floodplains, estuary and sediment plume. We introduce a Dam Environmental Vulnerability Index to quantify the current and potential impacts of dams in the basin. The scale of foreseeable environmental degradation indicates the need for collective action among nations and states to avoid cumulative, far-reaching impacts. We suggest institutional innovations to assess and avoid the likely impoverishment of Amazon rivers.

The field of Operations & Supply Chain Management (O&SCM) deals with large and complex structures. Evidence from practice suggests that management still runs in silos and decisions are often focused on specific functions as the totality of the problem and the impact on the broader organisation is not always understood. To manage such structures, managers have been investing in information technology to improve data availability and quality. Finally, good data is available with potential to enable holistic decision-making (DM). The field of analytics answers the need to transform data into information to support DM processes. Visual analytics rely specifically on visual representations to support DM processes. As visual analytics is still at its infancy, the aim is to identify what types of visual analytics has been used in empirical research, to support what decisions and its impact in O&SCM context. Evidence based literature review, also known as systematic literature review (SLR) method is used to review 41 papers. The most common type of visual analytics identified is modelling, mapping and visual interfaces between data and managers. These most often support Plan and Make type decisions. Vast majority of applications are identified as positive, enabling better understanding of the problem, greater management involvement in the process and better communication. Future research is needed to define the term “visual analytics” as the field is still at its infancy. Development and empirical testing is required of whether the identified visual tools are an enabler for holistic decisions in the O&SCM context.

No Abstract / Dissertation (LLM)--University of Pretoria, 2014. / hb2014 / Mercantile Law / unrestricted

This study analyzes federal and state pollution control and abatement legislation and provides a one-volume working explanation of those laws applicable to business operations. This analysis is limited to legislation aimed at controlling air and water pollution, and solid waste management.

M.Comm. ( Accounting) / Globally, the temperature is rising and some of the consequences are starting to show. This effect is known as global warming. The issue of global warming and environmental pollution is more serious than people realise as it is the starting point of potentially catastrophic events to come. The implementation of global emission reductions is imperative in order to prevent further global warming. All countries should be actively involved in the prevention of further global warming and the reduction of pollution. With the use of a comparative analysis of various environmental taxes internationally, the countries with established environmental tax frameworks can be used as a basis for the development of effective environmental tax frameworks in developing countries. This will ensure that developed as well as developing countries will be held accountable for their emissions and hopefully will make efforts to reduce their emissions. South Africa has very few environmental tax policies and the existing acts are not sufficient to ensure the effective reduction and management of its emissions. Successful environmental tax policies are those that are economically viable and easy to implement. This is achieved through successful implementation by the tax authorities as well as the taxpayers’ cooperation and acknowledgement of these policies.

Class of 2013 Abstract / Specific Aims: To assess associations between clinical and economic outcomes of metastatic thyroid cancer within inpatient settings in the United States from 2001-2010. To determine the direct inpatient burden of and describe the characteristics of patients and hospitals associated with metastatic thyroid cancer. Methods: A multivariate retrospective cohort study was performed on the Healthcare Cost and Utilization Project-Nationwide Inpatient Sample database, for the years 2001-2010, focusing on three main outcomes: inpatient mortality, inpatient charges, and inpatient length of stay. Regression analyses controlled for patient demographics, hospital characteristics, payer, clinical comorbidities, and site of metastases. Inclusion criteria included: age ≥ 18 years, any listed diagnosis of thyroid cancer, and any listed secondary malignancy. Main Results: Overall, 84,191 inpatient cases were observed for metastatic thyroid cancer with 3,032 resulting in mortality (3.6%). The total charges were $3.1 billion (USD 2012) for overall inpatient hospitalizations with average inpatient charges at $38,292 (SD±56,135) for each overall case and $80,948 (SD±117,645) for each mortality-only case. Higher inpatient mortality, charges, and length of stay were significantly associated with central nervous system and lung metastatic cancer sites (p < 0.01) and deficiency anemias, coagulopathy, fluid and electrolyte disorders, pulmonary circulation disorders, and weight loss comorbidities (p < 0.01). Conclusion: There is a considerable national inpatient burden of metastatic thyroid cancer. The analyses in this study quantify the associations and outcomes, and as such can be used to assist in the prediction of those outcomes and clinical decision-making.

Magister Artium (Psychology) - MA(Psych) / The purpose of the study was to investigate levels of occupational stress experienced by police officers and the strategies used to cope with stress. The study findings are based on a sample of 104 police officers from six police stations within the Cape Town area. The results indicated that participants have been in the police service for an average of 7.72 years, and have worked an average of 4.8 years at their present stations. The majority of participants are between 26-30 years old (31%), male (75%), married(51%), coloured (65%), constables (45%), Afrikaans speaking (47%), and have a matric qualification (70%). The Spielberger Police Stress Survey and the Brief COPE Inventory were used as data collection tools. The findings indicated that police officers were experiencing moderate levels of stress as an outcome of inherent and organisational occupational demands. Secondly, police officers were more likely to use problem-focussed coping strategies to manage occupational stress than maladaptive strategies. The limited use of avoidance coping strategies was surprising, given the elevated prevalence of both physical and psychological disorders within the police context. The results indicated no significant association between levels of distress and avoidance coping strategies. The potential adverse outcomes of severe stress within this group affect society in general more than stress from most other occupational groups. Addressing persistent stress within the organisation is imperative in ensuring a well-functioning police service, and ultimately, a secure and healthy society. / South Africa