French vertical-flow constructed wetlands (VFCW) directly treating raw wastewater are known to perform well on for SS, COD and nitrification. They are also known to robustly cope with hydraulic overloads during rainfall events. Although numerous systems have been installed in areas equipped with a combined sewer, the limits of stormwater acceptance remain ill-defined and need to be improved. Looking at the various VFCW designs and usages reported in the literature, it is difficult to draw any consensus on their hydraulic limits. Consequently, designing VFCW to accept hydraulic overloads is a complex task, as local context strongly impacts inlet flows produced during rainfall events. Dynamic models appear a requisite for filter design in such cases. Numerical CW models have essentially focused on horizontal flow, with few attempting to study VFCW dynamics which are more commonly tackled via mechanistic models. Although mechanistic models are powerful tools for describing processes within the VFCW, they are generally too complicated to be readily used by designers. The choice between detailed description and easy handling will depend on the modelling aims. If the aim is a global design tool, simplified models offer a good alternative. However, the simplified models geared to studying VFCW dynamics are extremely reduced. They are easy-handling for design and well-adapted to specific purposes (combined sewer overflow -CSO- treatment) but not necessarily to VFCW treating combined sewer wastewater, where long-term infiltration rates vary significantly. Consequently, this PhD thesis work focused on developing a simplified hydraulic model of VFCW to guide designers through the process of adapting VFCW systems to treat domestic wastewater in both dry and rain events. The simplified model makes it possible to link (i) hydraulics, by simulation of ponding time variations, (ii) biological performances, by establishing "dysfunction alerts" based on treatment performance assessment and variations in online N forms effluent from the young VFCW. These "dysfunction alerts" plot the maximal hydraulic load that a filter can accept without compromising its biological activity. The simplified model was used to model long-term hydraulics in the VFCW (i) to analyze the impact of local context and filter design on hydraulic overload acceptance (using "dysfunction alerts" and bypass discharges) and (ii) to propose VFCW designs for accepting hydraulic overload in different contexts. The modelling demonstrates that VFCW can limit days with bypass discharges to less than 20 times per year without jeopardizing filter performances. Moreover, the most problematic scenario on stormwater treatment remains a watershed with high imperviousness coefficient and low slope under a Bretagne-type climate, demonstrating that the filter is more sensitive to periodicity and duration than to intensity of rainfall events.

Employees in the Occupational Risk Division (ORD) of a large petrochemical company experience many difficult situations on a regular basis. This division of the company comprises the emergency services, the security and the occupational health divisions of the company. Even though every precaution is taken to ensure the safety of employees in the company, accidents and incidents do happen. The employees of the ORD are confronted with gruesome accidents, dangerous accident scenes where they have to enter when everyone else is evacuated, and security breeches where they may have to enter and resolve serious conflict situations. The possibility that their work climate may contributed to their mental health status is suggested. It is suspected that the stress of the job affects the mental health of the employees of the OCD, and ways need to be found to reduce these effects. The objective of this research was to determine the relationship between core self-evaluations, role overload, powerlessness and health indicators of employees in the ORD of a large petro-chemical company and to determine whether core self-evaluations act as a moderator in the relationship between role overload and powerlessness on the one hand and health indicators on the other hand. A cross-sectional design was used. The sample consisted of 299 employees from the Occupational Risk Division of the organization. Age, gender and level of education were included as control variables. A comprehensive survey containing the measuring instruments was administrated. Descriptive statistics and inferential statistics were used to analyse the data. Results obtained indicated that some of the scales were not reliable. Powerlessness was dropped from the analysis and qualitative and quantitative role overload were collapsed into a total overload measure. The results showed that a negative relationship exists between role overload and core self-evaluations. A positive relationship exists between role overload and neuroticism, poor health and depression. Self-esteem, self-efficacy and locus of control are negatively related to neuroticism and health, and neuroticism is positively related to poor health. Depression was predicted by experiences of overload, levels of self-efficacy, locus of control and negative affect (Neuroticism). General health was predicted by experiences of overload, locus of control, neuroticism and the interaction between overload and self-esteem. None of the scales predict medication use to a significant degree. Results further indicated that only self-esteem acts as a moderator in the relationship between role overload and general health, but none of the variables of core self-evaluations act as a moderator between role overload and depression or between role overload and the use of medication. By way of conclusion, recommendations for future research were made. / Thesis (M.A. (Industrial Psychology))--North-West University, Potchefstroom Campus, 2008.

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Employees in the Occupational Risk Division (ORD) of a large petrochemical company experience many difficult situations on a regular basis. This division of the company comprises the emergency services, the security and the occupational health divisions of the company. Even though every precaution is taken to ensure the safety of employees in the company, accidents and incidents do happen. The employees of the ORD are confronted with gruesome accidents, dangerous accident scenes where they have to enter when everyone else is evacuated, and security breeches where they may have to enter and resolve serious conflict situations. The possibility that their work climate may contributed to their mental health status is suggested. It is suspected that the stress of the job affects the mental health of the employees of the OCD, and ways need to be found to reduce these effects. The objective of this research was to determine the relationship between core self-evaluations, role overload, powerlessness and health indicators of employees in the ORD of a large petro-chemical company and to determine whether core self-evaluations act as a moderator in the relationship between role overload and powerlessness on the one hand and health indicators on the other hand. A cross-sectional design was used. The sample consisted of 299 employees from the Occupational Risk Division of the organization. Age, gender and level of education were included as control variables. A comprehensive survey containing the measuring instruments was administrated. Descriptive statistics and inferential statistics were used to analyse the data. Results obtained indicated that some of the scales were not reliable. Powerlessness was dropped from the analysis and qualitative and quantitative role overload were collapsed into a total overload measure. The results showed that a negative relationship exists between role overload and core self-evaluations. A positive relationship exists between role overload and neuroticism, poor health and depression. Self-esteem, self-efficacy and locus of control are negatively related to neuroticism and health, and neuroticism is positively related to poor health. Depression was predicted by experiences of overload, levels of self-efficacy, locus of control and negative affect (Neuroticism). General health was predicted by experiences of overload, locus of control, neuroticism and the interaction between overload and self-esteem. None of the scales predict medication use to a significant degree. Results further indicated that only self-esteem acts as a moderator in the relationship between role overload and general health, but none of the variables of core self-evaluations act as a moderator between role overload and depression or between role overload and the use of medication. By way of conclusion, recommendations for future research were made. / Thesis (M.A. (Industrial Psychology))--North-West University, Potchefstroom Campus, 2008.

The fatigue of materials and structures is a subject that has been under investigation for almost 160 years; yet reliable fatigue life predictions are still more of an empirical art than a science. The traditional safe-life approach to fatigue design is based upon the total time to failure of a virtually defect free component. This approach is heavily reliant on the use of safety factors and empirical equations, and therefore much scatter in the fatigue life predictions is normally observed. Furthermore, the safe-life approach is unsuitable for many important applications such as aircraft, pressure vessels, welded structures, and microelectronic devices. In these applications the existence of initial defects is practically unavoidable and the time of propagation from an initial defect to final failure is comparable with the total life of the component. In the early 1970’s, the aircraft industry pioneered a new approach for the analysis of fatigue crack growth, known as damage tolerant design. This approach utilises fracture mechanics principles to consider the propagation of fatigue cracks from an initial crack length until final fracture, or a critical crack length, is reached. Since the first implementation of damage tolerant design, much research and development has been undertaken. In particular, theoretical and experimental fracture mechanics techniques have been utilised for the investigation of a wide variety of fatigue crack growth phenomena. One such example is the retardation and acceleration in crack growth rate caused by spike overloads or underloads. It is generally accepted, however, that the current level of understanding of fatigue crack growth phenomena and the adequacy of fatigue life prediction techniques are still far from satisfactory. This thesis theoretically investigates various non-linear individual and interaction phenomena associated with fatigue crack growth. Specifically, the effect of plate thickness on crack growth under constant amplitude loading, crack growth retardation due to an overload cycle, and small crack growth from sharp notches are considered. A new semianalytical method is developed for the investigations, which utilises the distributed dislocation technique and the well-known concept of plasticity-induced crack closure. The effects of plate thickness are included through the use of first-order plate theory and a fundamental solution for an edge dislocation in plate of arbitrary thickness. Numerical results are obtained via the application of Gauss-Chebyshev quadrature and an iterative procedure. The developed methods are verified against previously published theoretical and experimental data. The elastic out-of-plane stress and displacement fields are first investigated using the developed method and are found to be in very good agreement with past experimental results and finite element simulations. Crack tip plasticity is then introduced by way of a strip-yield model. The effects of thickness on the crack tip plasticity zone and plasticity-induced crack closure are studied for both small and large-scale yielding conditions. It is shown that, in general, an increase in plate thickness will lead to a reduction in the extent of the plasticity and associated crack closure, and therefore an increase in the crack growth rates. This observation is in agreement with many findings of past experimental and theoretical studies. An incremental crack growth scheme is implemented into the developed method to allow for the investigation of variable amplitude loading and small fatigue crack growth. The case of a single tensile overload is first investigated for a range of overload ratios and plate thicknesses. This situation is of practical importance as an overload cycle can significantly increase the service life of a cracked component by temporarily retarding the crack growth. Next to be studied is growth of physically small cracks from sharp notches. Fatigue cracks typically initiate from stress concentrations, such as notches, and can grow at rates higher than as predicted for a long established crack. This can lead to non-conservative estimates for the total fatigue life of a structural component. For both the overload and small crack cases, the present theoretical predictions correlate well with past experimental results for a range of materials. Furthermore, trends observed in the experiments match those of the predictions and can be readily explained through use of crack closure arguments. This thesis is presented in the form of a collection of published or submitted journal articles that are the result of research by the author. These nine articles have been chosen to best demonstrate the development and application of the new theoretical techniques. Additional background information and an introduction into the chosen field of research are provided in order to establish the context and significance of this work. / http://proxy.library.adelaide.edu.au/login?url= http://library.adelaide.edu.au/cgi-bin/Pwebrecon.cgi?BBID=1349588 / Thesis (Ph.D.) - University of Adelaide, School of Mechanical Engineering, 2008

This thesis presents a program of research exploring the multilevel organisational structure of fleet safety management. The aim of this research was to investigate three current fleet safety initiatives, and individual and contextual factors influencing safe driving behaviour in a work vehicle. Three studies were conducted to achieve this aim. This research utilised a sample of employees from a range of Queensland Government agencies.----- Study one evaluated three current fleet safety initiatives within the Queensland Government. From a sample of fleet co-ordinators (N=24) and drivers (N=88), this study established the extent to which specific psychological processes underlying the fleet safety initiatives were adopted, and the attitude change associated with their use. This study found mixed support for the Hypotheses, with the influence of the fleet safety initiatives on fleet co-ordinators' and drivers' attitude change being consistent with processes associated with the persuasive communication framework, and behaviour management. However, the study found no support for the behavioural management processes hypothesised to underlie the incentive scheme (CPP). The findings of the study suggested that while fleet safety initiatives can have an influence on fleet co-ordinator and driver attitude change, their impact depends on the extent to which safety issues are viewed as relevant, and the extent to which there is reinforcement within the organisational environment to support these safety initiatives. Therefore, the findings from this study, combined with existing research into the impact of safety climate, suggest the workplace context needs to be taken into account. For this reason, study two investigated the role of perceptions of the safety climate, in addition to individual attributes, as predictors of self-reported crash involvement.----- Study two applied a framework incorporating driver attributes, including attitudes towards traffic safety and self-efficacy, and drivers' perceptions of the safety climate, as predictors of self-reported crashes in a work vehicle. Within this framework, drivers' perception of the safety climate, and their individual attributes were conceptualised as antecedents of driving performance, and driver safety motivation and knowledge mediated the relationship between these factors and self-reported crashes. A total of 385 drivers participated in this study, which found motivation to drive safely mediated the relationship between driver attributes and self-reported crashes. The initial analysis did not find a significant relationship between safety climate and safety motivation. However, posthoc analyses exploring this non-significant relationship found managerial safety values could be distinguished from other facets of the safety climate construct. Subsequently, the results indicated managerial safety values predicted safety motivation, when drivers perceived a strong safety climate. This study provided a more thorough understanding of the variables predicting driver behaviour at an individual level of analysis. However, a shortcoming is the study did not consider the various influences impacting on drivers' safety perceptions, and individual attributes within the context of the work environment.----- Study three extended on the framework established in study two, and investigated the contribution of leader attributes to the prediction of drivers' safety perceptions, and individual attributes. The leader attribute measures, specifically, perceptions of the safety climate, motivation, knowledge, and work overload were collected from a sample of fleet co-ordinators (N=52) and supervisors (N=88). Through multi-level analyses, both supervisors and fleet co-ordinators were shown to influence the safety perceptions and individual attributes of individuals who drive work vehicles. Support was found for positive relationships between supervisor safety knowledge, and the individual attributes. However, there was a large amount of variation due to group membership unaccounted for by supervisor safety knowledge and the safety performance factors investigated within the supervisor groups. These findings suggested supervisors may not be interacting with drivers in relation to fleet safety matters, but that other factors associated with work group membership are having an impact on drivers' safety perceptions. In comparison, there was a small amount of variation accounted for by fleet co-ordinator group membership. However, the results suggested the fleet co-ordinator leader attributes accounted for a high percentage of this variation in group membership. Support was found for a positive relationship between fleet co-ordinator safety perceptions, and driver safety perceptions. Other results found fleet co-ordinators were engaging in higher workloads to enhance the safety perceptions, and attitudes towards traffic safety of drivers within their groups.----- Overall, these studies establish a multilevel organisational process of effect, whereby individual and leader attributes, and organisational initiatives all play a role in influencing the safety performance of work-related drivers. The results also indicated an unclear structure in the management of fleet safety, as perceived by drivers, and through the roles and responsibilities of supervisors and fleet co-ordinators. The implications of these results for the management of fleet safety are discussed.

This dissertation argues that admission control should be applied as early as possible within a system. To that end, this dissertation examines the benefits and trade-offs involved in applying admission control to a networked computer system at the level of the network interface hardware. Admission control has traditionally been applied in software, after significant resources have already been expended on processing a request. This design decision leads to systems whose algorithmic cost is a function of the load applied to the system, rather than the load admitted to the system. By performing admission control at the network interface, it is possible to develop systems whose algorithmic cost is a function of load admitted to the system, rather than load applied to the system. Such systems are able to deal with excessive applied loads without exhibiting performance degradation. This dissertation first examines existing admission control approaches, focussing on the cost of admission control within those systems. It then goes on to develop a model of system behaviour under overload, and the impact of admission control on that behaviour. A new class of admission control mechanisms which are able to perform load rejection using the network interface hardware are then described, along with a prototype implementation using commodity hardware. A prototype implementation in the FreeBSD operating system is evaluated for a variety of network protocols and performance is compared to the standard FreeBSD implementation. Performance and scalability under overload is significantly improved.

[Truncated abstract. Please see the pdf format for the complete text.] The discovery of the C282Y mutation and its role in the development of hereditary haemochromatosis has allowed a greater understanding into the effects of iron overload and its involvement in other conditions such as diabetes and heart disease. It has also allowed the better classification of heterozygotes, who were previously only diagnosed through the use of family studies. There are however, areas of conflict between phenotyping and genotyping methods. My research involved examining the relationship between Haemochromatosis and certain diseases such as diabetes and heart disease; genotyping versus phenotyping discrepancies and the possible interaction of secondary mutations. In Chapter 3 a population study was undertaken with the aim of comparing genotyping versus phenotyping methods as well as increasing general practitioner awareness regarding hereditary haemochromatosis and its diagnosis. It was determined that a minimum of 5000 subjects would be required to give the study sufficient power. Individuals were to be between the ages of 20—40 years, and thus presumably presymptomatic. Participation was entirely voluntary and a consent form was to be signed. Recruitment of subjects proved to be difficult and there was a selective bias towards individuals already displaying symptoms of haemochromatosis. In total less than a 100 subjects were recruited for the study. There were several issues encountered in the implementation of this study. Firstly the number of GPs participating was probably insufficient to recruit the subjects required. A more extensive campaign was probably required to enroll more GPs. Secondly it is very difficult for a busy GP to find the time necessary to explain the study to each of his patients and to get them to sign the consent form. Finally a bias developed in some of the requests. The subjects participating in this study were supposed to be random but in many cases the GPs had enrolled them in the study because they had symptoms of iron overload. In effect the biggest obstacle this study faced was the recruitment of subjects. Due to the small number of subjects little statistical data could be obtained from this study. It was noted, however, that genotyping methods detected two individuals who were homozygous for the C282Y mutation. Both also had increased transferrin saturation levels. Phenotyping detected 5 individuals with increased transferrin saturation. The three others detected via phenotyping were C282Y heterozygotes. Haemochromatosis has long been though to be related to the development of diabetes due to the effect of iron overload on the pancreas. If this is so it would be logical to assume that the prevalence of haemochromatosis would be higher in a diabetic population. Chapter 4 examined the possibility that diabetics have a higher frequency of the C282Y mutation. A population group consisting of 1355 diabetics was genotyped for the C282Y mutation and iron studies were performed on all heterozygotes and C282Y homozygotes. Initial findings indicated that there was a significant difference between the diabetic and control population. However, this finding was the opposite of what was expected, there seemed to be a decreased frequency of the Y allele in the diabetic population rather than an increased one. The control and diabetic populations were not matched in terms of ethnicity. The removal of the ethnic bias in the diabetic population altered the statistics so there was no longer a significant difference between the two groups. This study highlighted the importance of using appropriate control populations as comparison groups. The final results of the study indicated that there was no significant difference between the diabetic population and the control population. This would seem to indicate that there is not an increased occurrence of the C282Y mutation in the diabetic population when compared to the control group. Chapter 5 considered the possible association between C282Y heterozygosity and cardiovascular disease as well as the potential for early mortality. Several recent studies have indicated that C282Y heterozygosity may be a risk factor for the development of atherosclerosis, possibly on the basis of increased iron loading. Using a control population and a population of individuals with known coronary events the incidence of the C282Y mutation was compared against other risk factors. C282Y heterozygosity did not appear to be a risk factor for atherosclerosis. There was however, a statistically significant link between increased ferritin in women and carotid plaques. A population of elderly women was genotyped in order to examine the effects of C282Y heterozygosity on longevity. The first hypothesis addressed in chapter 5 was that C282Y heterozygosity was a risk factor for the development of coronary heart disease.

This study aimed to verify the influence of epistemic motivation in decision making. We addressed the following themes: decision-making, information overload; epistemic motivation; amount of information, satisfaction, and confusion. In order to achieve this purpose, we developed a task context in which it was possible to study multiple objectives in multiple scenarios, with the aid of a Multiple Criteria Decision Support System (MCDSS) and without the aid of a MDA. We carried out an experimental research in the laboratory using a decision task with multiple alternatives and criteria, with twenty-nine people divided into three experimental groups according to the number of attributes and alternatives. The task, which simulates the purchase of a bottle of wine for personal consumption, was structured in order to create a decision environment with the help of the MCDSS M-MACBETH or without it, by using the Think Aloud verbal protocol. After formulating and testing the hypotheses, we found that the effect of the information overload is not weaker for individuals with high epistemic motivation; the moderating effect of epistemic motivation was not weaker for the alternatives than for attributes; and individuals with low epistemic motivation did not notice the overload in the form of alternatives and attributes, resulting in dissatisfaction and/or confusion. Thus, we found no statistical evidence to confirm the hypotheses of this study. The discussion of the results reveals important particularities in decision-making process since participants had to choose, and people usually avoid or postpone their choices. By pointing to the role of complexity of information, a broader conception of choice is suggested. This broader perspective should allow forecasts which variables that can facilitate or hinder the emergence of effects of information overload. Regarding epistemic motivation, the findings do not reveal significant differences in the distributions of choices made according to different motivational conditions. This suggests that when faced with complex information, everyone makes the necessary effort, whether they are high or low in epistemic motivation; however, we emphasize that this topic needs further clarification. / Este estudo teve como objetivo verificar a influência da motivação epistêmica no processo decisório. Foram abordados os temas processo decisório; sobrecarga de informação; motivação epistêmica; quantidade de informações, satisfação e confusão. Para atingir o objetivo proposto, foi desenvolvida uma tarefa em que fosse possível estudar múltiplos objetivos em múltiplos cenários, com o auxílio de um Sistema Multicritério de Apoio à Decisão (SAD) e sem o auxílio de um SAD. Realizou-se uma pesquisa experimental em laboratório, utilizando-se uma tarefa decisória com múltiplas alternativas e critérios com vinte e nove sujeitos separados em três grupos experimentais, de acordo com a quantidade de atributos e alternativas. A tarefa, que simula a compra de uma garrafa de vinho para consumo próprio, foi estruturada com o intuito de criar um ambiente de decisão para a realização, com o auxílio do SAD M-MACBETH e sem o auxílio deste, sendo utilizado o protocolo verbal Think Aloud. Testando-se a hipótese, verificou-se que: o efeito da sobrecarga de informação não foi mais fraca para indivíduos com alta motivação epistêmica; o efeito moderador da motivação epistêmica não foi mais fraco nas alternativas do que para os atributos; e indivíduos com baixa motivação epistêmica não perceberam a sobrecarga na forma de alternativas e atributos, resultando em insatisfação e/ou confusão. Assim, não foram encontradas comprovações estatísticas para afirmar a hipótese deste estudo. A discussão dos resultados revela importantes particularidades no processo de decisão, uma vez que os participantes tiveram que escolher, enquanto as pessoas costumam evitar ou adiar a escolha. Ao apontar para o papel da complexidade de informação, é sugerida uma concepção mais ampla sobre a escolha. Tal perspectiva mais ampla deve permitir previsões de quais variáveis podem facilitar ou dificultar o surgimento de efeitos de sobrecarga de informações. Com relação à motivação epistêmica, os achados, neste estudo, não revelam diferenças significativas entre as distribuições das escolhas feitas de acordo com as diferentes condições motivacionais. Isso sugere que, quando confrontados com informações complexas, todos fazem o esforço necessário, independente de serem altos ou baixos na motivação epistêmica, destacando-se, porém, que esse tópico carece de um aprofundamento maior.