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No description available.

No description available.

No description available.

From its beginnings as a single link between two research institutions in 1969, the Internet has grown in size and scope, to become a global internetwork connecting over 700 million computers, and 1.7 billion users. No longer a niche facility for scientific collaboration, the Internet now touches the lives of the world’s population, irrespective of their occupation or geography. It is used by people the world over, to pay bills, read the news, listen to music, watch videos, telephone or video-conference friends and family, and much more. The Internet is the premier communications network of our age. Unfortunately, however, there are some respects in which the Internet lags the networks it replaces. In particular, with respect to reliability, the Internet falls far short of the Public Switched Telephone Network which proceeded it. Whereas the PSTN sought, and often delivered the vaunted “five nines” of reliability, the Internet struggles to compete. As for the cause of this reliability shortfall, available evidence indicates that much of the shortfall is due to the unreliability of IP routers themselves. Given the importance of a reliable Internet to contemporary society, vendors and researchers have proposed a number of solutions to either improve the reliability of individual IP routers, or to make networks more resilient to the unavailability of a single router. While having some promise, these existing solutions face significant obstacles to widespread deployment. Thus, in this dissertation, we endeavor to find or construct a practical, readily deployable, method for mitigating the outages caused by IP routers. To achieve our goal, we take inspiration from previous proposals, which advocated the use of link migration. These proposals improve network resilience, by moving links away from a failed (or failing) router, to an in-service router. To understand the constraints of a practical solution, and resolve the limitations of previous proposals, we conduct extensive experimentation, and study source code and protocol specifications. Using the insights produced by these studies, we construct a practical, readily deployable migration solution with sub-second outage times.

In order to survive and to prosper in a continuously changing environment, organisations need energetic and motivated employees, i.e. employees who are psychologically well. Burnout and work engagement are important focus areas for research regarding the wellness of employees. In order to ensure work wellness (i.e. low burnout and high work engagement), it is necessary to assess the current level thereof. This assessment should be done on an individual level, and scores should also be aggregated to study patterns in specific occupations, sections, units, and organisations. However, before the levels of wellness can be assessed, a valid and reliable measuring instrument is needed. The objectives of the study were to to investigate the construct validity and reliability of the Maslach Burnout Inventory - General Survey, and Utrecht Work Engagement Scale for train drivers, and to test assess the relationship between burnout and work engagement. A cross-sectional survey design was used, whereby a sample (JV= 332) was drawn from train drivers in Spoornet. The measuring instruments utilised in this study were The Maslach Burnout Inventory - General Survey (MBI-GS) and the Utrecht Work Engagement Scale (UWES) and the Cognitive Weariness Scale (CWS). Principal components extraction was used prior to principal factor extraction to estimate the number of factors, presence of outliers and factorability of correlation matrices. Structural equation modelling was used to test the relationship between the constructs. The results showed that burnout consisted of four factors, namely Exhaustion, Cognitive Weariness, Professional Efficacy and Cynicism. Work Engagement showed a one-factor structure. Structural equation modelling showed that work wellness consists of two factors, namely energy (including Exhaustion, Cognitive Weariness, and Cynicism), and motivation (Work Engagement and Professional Efficacy). The results also showed that Exhaustion is practically significantly and positively related to Cynicism (large effect) and Cognitive Weariness (medium effect). Exhaustion is also practically significantly and negatively related to Work Engagement (large effect) and Professional Efficacy (medium effect). Cynicism is practically significantly and positively related to Cognitive Weariness (medium effect) and negatively related to Work Engagement (larger effect) and Professional Efficacy (medium effect). Work Engagement is practically significantly and positively related to Professional Efficacy (large effect). The sten scores of the train drivers were low average on Exhaustion (4,02) and on Cynicism (4,38%). The sten scores were above average on Vigour (7,48%) and on Dedication (7,96%). About 52,l%o of the train drivers reported low on Exhaustion and 42,5% reported low on Cynicism. As as far as Vigour and Dedication are concerned, 57% showed high scores on Vigour and 63,9% of train drivers showed high scores on dedication. The structure of well-being was equivalent for Afrikaans and African language groups. Recommendations for future research were made. / Thesis (M.Com. (Industrial Psychology))--North-West University, Potchefstroom Campus, 2009.

In order to survive and to prosper in a continuously changing environment, organisations need energetic and motivated employees, i.e. employees who are psychologically well. Burnout and work engagement are important focus areas for research regarding the wellness of employees. In order to ensure work wellness (i.e. low burnout and high work engagement), it is necessary to assess the current level thereof. This assessment should be done on an individual level, and scores should also be aggregated to study patterns in specific occupations, sections, units, and organisations. However, before the levels of wellness can be assessed, a valid and reliable measuring instrument is needed. The objectives of the study were to to investigate the construct validity and reliability of the Maslach Burnout Inventory - General Survey, and Utrecht Work Engagement Scale for train drivers, and to test assess the relationship between burnout and work engagement. A cross-sectional survey design was used, whereby a sample (JV= 332) was drawn from train drivers in Spoornet. The measuring instruments utilised in this study were The Maslach Burnout Inventory - General Survey (MBI-GS) and the Utrecht Work Engagement Scale (UWES) and the Cognitive Weariness Scale (CWS). Principal components extraction was used prior to principal factor extraction to estimate the number of factors, presence of outliers and factorability of correlation matrices. Structural equation modelling was used to test the relationship between the constructs. The results showed that burnout consisted of four factors, namely Exhaustion, Cognitive Weariness, Professional Efficacy and Cynicism. Work Engagement showed a one-factor structure. Structural equation modelling showed that work wellness consists of two factors, namely energy (including Exhaustion, Cognitive Weariness, and Cynicism), and motivation (Work Engagement and Professional Efficacy). The results also showed that Exhaustion is practically significantly and positively related to Cynicism (large effect) and Cognitive Weariness (medium effect). Exhaustion is also practically significantly and negatively related to Work Engagement (large effect) and Professional Efficacy (medium effect). Cynicism is practically significantly and positively related to Cognitive Weariness (medium effect) and negatively related to Work Engagement (larger effect) and Professional Efficacy (medium effect). Work Engagement is practically significantly and positively related to Professional Efficacy (large effect). The sten scores of the train drivers were low average on Exhaustion (4,02) and on Cynicism (4,38%). The sten scores were above average on Vigour (7,48%) and on Dedication (7,96%). About 52,l%o of the train drivers reported low on Exhaustion and 42,5% reported low on Cynicism. As as far as Vigour and Dedication are concerned, 57% showed high scores on Vigour and 63,9% of train drivers showed high scores on dedication. The structure of well-being was equivalent for Afrikaans and African language groups. Recommendations for future research were made. / Thesis (M.Com. (Industrial Psychology))--North-West University, Potchefstroom Campus, 2009.

No description available.

No description available.

This thesis describes the development of a computer-aided fault tree synthesis package for application in the process industries. It builds on the previous research work carried out in the Plant Engineering Group at Loughborough University. The emphasis has been put on describing the underlying methodology as opposed to the actual computer programs. The methodology described was developed by modelling a number of "real" systems, which had already been analysed using manual fault tree construction techniques by British Gas plc. Additionally a number of standard examples from the literature were utilised, as well as a large number of contrived examples to fully evaluate the package. The problems encountered and their solution are described. The culmination of this project was the implementation of the computer package at the Midlands Research Station of British Gas plc. It is not intended that the package should replace the fault tree expert. It should rather be viewed as a tool to facilitate the work of the process engineer, particularly during the design phase. This should enable the evaluation of many more options, which would otherwise have been proved prohibitive by the effort required to manually synthesise the fault trees.