Afscheidscollege Universiteit Maastricht. / Met lit.opg.

Proefschrift Rijksuniversiteit Limburg, Maastricht. / Auteursnaam op omslag: Cor Meesters. Met bibliogr., lit. opg. - Met samenvatting in het Nederlands.

Proefschrift Maastricht. / Met lit. opg. - Met samenvatting in het Nederlands.

Proefschrift Maastricht. / Lit. opg. - Met een samenvatting in het Nederlands.

Proefschrift Maastricht. / Lit. opg.: p. 99-110. - Met samenvatting in het Nederlands.

Proefschrift Maastricht. / Lit. opg.: p. 97-103. - Met samenvatting in het Nederlands.

In order to be sustainable, companies have to adapt in the ever–changing market and economic conditions which are often unpredictable. The adaptation to these challenges rests with employees who have to stay motivated and psychologically well. The environmental working conditions are often undesirable The objective of this study was to evaluate the psychometric performance of the Utrecht Work Engagement Scale (UWES) and the Oldenburg Burnout inventory (OLBI) within the cement factory. A random sampling approach was adopted by distributing a questionnaire for the purposes of achieving the general research objective with an availability sample (N = 187). The UWES and OLBI were administered. Exploratory factor analysis, descriptive statistics, Cronbach alpha coefficients, Pearson product–moment correlations and MANOVA's were used to analyse the data. The outcome of the study through literature review confirmed that work engagement and burnout are two important components of employee wellbeing. The factor loadings of the UWES and OLBI resulted in a two–factor structure for both the UWES and OLBI. The two factor structure for the UWES were labelled as Vigour/Dedication and Absorption. The twofactor structure for the OLBI was labelled Disengagement and Exhaustion. A small number of items were retained for the OLBI. The internal consistency of the UWES was found to be well above the acceptable level with the alpha coefficients exceeding 0,70. The internal consistency for the OLBI was found to be lower than the 0,70 level. Data analysis further showed that correlations between engagement and burnout were statistically insignificant. Data analysis also showed that there were no vi significant differences for age and gender for both engagement and burnout, however there is a significant difference in race and language with regard to engagement but none for burnout. Limitations within the study were identified and recommendations for future research were made. / Thesis (M.A. (Industrial Psychology))--North-West University, Potchefstroom Campus, 2011.

In order to be sustainable, companies have to adapt in the ever–changing market and economic conditions which are often unpredictable. The adaptation to these challenges rests with employees who have to stay motivated and psychologically well. The environmental working conditions are often undesirable The objective of this study was to evaluate the psychometric performance of the Utrecht Work Engagement Scale (UWES) and the Oldenburg Burnout inventory (OLBI) within the cement factory. A random sampling approach was adopted by distributing a questionnaire for the purposes of achieving the general research objective with an availability sample (N = 187). The UWES and OLBI were administered. Exploratory factor analysis, descriptive statistics, Cronbach alpha coefficients, Pearson product–moment correlations and MANOVA's were used to analyse the data. The outcome of the study through literature review confirmed that work engagement and burnout are two important components of employee wellbeing. The factor loadings of the UWES and OLBI resulted in a two–factor structure for both the UWES and OLBI. The two factor structure for the UWES were labelled as Vigour/Dedication and Absorption. The twofactor structure for the OLBI was labelled Disengagement and Exhaustion. A small number of items were retained for the OLBI. The internal consistency of the UWES was found to be well above the acceptable level with the alpha coefficients exceeding 0,70. The internal consistency for the OLBI was found to be lower than the 0,70 level. Data analysis further showed that correlations between engagement and burnout were statistically insignificant. Data analysis also showed that there were no vi significant differences for age and gender for both engagement and burnout, however there is a significant difference in race and language with regard to engagement but none for burnout. Limitations within the study were identified and recommendations for future research were made. / Thesis (M.A. (Industrial Psychology))--North-West University, Potchefstroom Campus, 2011.

Technological innovation that empowers tiny low-cost transceivers to operate with a high degree of utilisation efficiency in multihop wireless mesh networks is contributed in this dissertation. Transmission scheduling and joint source-channel-network coding are two of the main aspects that are addressed. This work focuses on integrating recent enhancements such as wireless network coding and temporal reuse into a cross-layer optimisation framework, and to design a joint coding scheme that allows for space-optimal transceiver implementations. Link-assigned transmission schedules with timeslot reuse by multiple links in both the space and time domains are investigated for quasi-stationary multihop wireless mesh networks with both rate and power adaptivity. Specifically, predefined cross-layer optimised schedules with proportionally fair end-to-end flow rates and network coding capability are constructed for networks operating under the physical interference model with single-path minimum hop routing. Extending transmission rights in a link-assigned schedule allows for network coding and temporal reuse, which increases timeslot usage efficiency when a scheduled link experiences packet depletion. The schedules that suffer from packet depletion are characterised and a generic temporal reuse-aware achievable rate region is derived. Extensive computational experiments show improved schedule capacity, quality of service, power efficiency and benefit from opportunistic bidirectional network coding accrued with schedules optimised in the proposed temporal reuse-aware convex capacity region. The application of joint source-channel coding, based on fountain codes, in the broadcast timeslot of wireless two-way network coding is also investigated. A computationally efficient subroutine is contributed to the implementation of the fountain compressor, and an error analysis is done. Motivated to develop a true joint source-channel-network code that compresses, adds robustness against channel noise and network codes two packets on a single bipartite graph and iteratively decodes the intended packet on the same Tanner graph, an adaptation of the fountain compressor is presented. The proposed code is shown to outperform a separated joint source-channel and network code in high source entropy and high channel noise regions, in anticipated support of dense networks that employ intelligent signalling. AFRIKAANS : Tegnologiese innovasie wat klein lae-koste kommunikasie toestelle bemagtig om met ’n hoë mate van benuttings doeltreffendheid te werk word bygedra in hierdie proefskrif. Transmissie-skedulering en gesamentlike bron-kanaal-netwerk kodering is twee van die belangrike aspekte wat aangespreek word. Hierdie werk fokus op die integrasie van onlangse verbeteringe soos draadlose netwerk kodering en temporêre herwinning in ’n tussen-laag optimaliserings raamwerk, en om ’n gesamentlike kodering skema te ontwerp wat voorsiening maak vir spasie-optimale toestel implementerings. Skakel-toegekende transmissie skedules met tydgleuf herwinning deur veelvuldige skakels in beide die ruimte en tyd domeine word ondersoek vir kwasi-stilstaande, veelvuldige-sprong draadlose rooster netwerke met beide transmissie-spoed en krag aanpassings. Om spesifiek te wees, word vooraf bepaalde tussen-laag geoptimiseerde skedules met verhoudings-regverdige punt-tot-punt vloei tempo’s en netwerk kodering vermoë saamgestel vir netwerke wat bedryf word onder die fisiese inmengings-model met enkel-pad minimale sprong roetering. Die uitbreiding van transmissie-regte in ’n skakel-toegekende skedule maak voorsiening vir netwerk kodering en temporêre herwinning, wat tydgleuf gebruiks-doeltreffendheid verhoog wanneer ’n geskeduleerde skakel pakkie-uitputting ervaar. Die skedules wat ly aan pakkie-uitputting word gekenmerk en ’n generiese temporêre herwinnings-bewuste haalbare transmissie-spoed gebied word afgelei. Omvattende berekenings-eksperimente toon verbeterde skedulerings kapasiteit, diensgehalte, krag doeltreffendheid asook verbeterde voordeel wat getrek word uit opportunistiese tweerigting netwerk kodering met die skedules wat geoptimiseer word in die temporêre herwinnings-bewuste konvekse transmissie-spoed gebied. Die toepassing van gesamentlike bron-kanaal kodering, gebaseer op fontein kodes, in die uitsaai-tydgleuf van draadlose tweerigting netwerk kodering word ook ondersoek. ’n Berekenings-effektiewe subroetine word bygedra in die implementering van die fontein kompressor, en ’n foutanalise word gedoen. Gemotiveer om ’n ware gesamentlike bron-kanaal-netwerk kode te ontwikkel, wat robuustheid byvoeg teen kanaal geraas en twee pakkies netwerk kodeer op ’n enkele bipartiete grafiek en die beoogde pakkie iteratief dekodeer op dieselfde Tanner grafiek, word ’n aanpassing van die fontein kompressor aangebied. Dit word getoon dat die voorgestelde kode ’n geskeide gesamentlike bron-kanaal en netwerk kode in hoë bron-entropie en ho¨e kanaal-geraas gebiede oortref in verwagte ondersteuning van digte netwerke wat van intelligente sein-metodes gebruik maak. / Dissertation (MEng)--University of Pretoria, 2011. / Electrical, Electronic and Computer Engineering / unrestricted

Depression is one of the most debilitating, widespread and costly health problems worldwide and has a high prevalence in almost every society. Research suggests that depression affects an individual‟s work engagement levels, burnout levels and the occurrence of stress-related ill health symptoms. However, it is unclear whether these findings would differ among individuals who reported that they suffer from depression and receive medical treatment for it, individuals who reported that they are unsure whether they suffer from depression, and individuals who reported that they do not suffer from depression. This study is quantitative in nature and a cross-sectional design was used. The study population consisted of 15 664 participants from several sectors in South Africa. The participants also differed in terms of gender, age, race, marital status, educational level, language and the province where they reside. The sample population was thus representative of the diverse population of South Africa. The SAEHWS, a self-report instrument based on the dual-process model of work-related well-being, was used to measure all constructs. The participants were divided into three groups, i.e. individuals who reported that they suffer from depression and are currently receiving medical treatment for depression, individuals who reported that they are uncertain whether they suffer from depression, and individuals who reported that they do not suffer from depression. Frequencies were used to determine the prevalence of depression in the three different groups and MANOVA (multivariate analysis of variance) was used to determine the significance of differences between the levels of work engagement, burnout and stress-related ill health symptoms of the three different groups (individuals who reported that they suffer from depression, individuals who reported that they are uncertain whether they suffer from depression, and those who reported that they do not suffer from depression). The results showed that 18,3% of the population reported that they suffer from depression and receive medical treatment for depression, 16,7% of the population reported that they are unsure whether they suffer from depression and 65% reported that they do not suffer from depression. Furthermore, it was found that depression significantly influences work engagement levels negatively and that it significantly influences burnout levels and the occurrence of stress-related ill health symptoms positively. This study will make organisations aware of the effect of depression on an individual‟s well-being and of the fact that depression is a factor to be reckoned with. Employers should consider ways to assist employees who suffer from depression and should learn how to act preventatively to decrease any further occurrence. / Thesis (M.Com. (Industrial Psychology))--North-West University, Potchefstroom Campus, 2011