M.Bibl. / Please refer to full text to view abstract

The present study sought to investigate the effects of a Standard workstation, designed for “average” users, on an anthropometrically diverse sample of computer operators, and to assess whether physical and perceptual responses, as well as performance efficiency were dependent on stature. Further investigation assessed the influence of personalised adjustments to the Standard workstation, based on the anthropometric characteristics of the subjects, as well as the introduction of a custom-designed ‘floating’ wrist support, on subject responses. All subjects (n=30) were tested in each of the three workstations: Standard, Personalised and Wrist Support. For analysis of responses in the Standard workstation, subjects were divided into three groups depending on their stature: Short (<1650mm), Medium (1650mm to 1800mm), Tall (>1800mm). The musculoskeletal responses indicated that Tall subjects were forced to adopt the most awkward general body postures as a result of the low computer screen. However, the low screen allowed for the Short subjects to adopt the most natural general body postures, although levels of muscular activity in the upper trapezius suggest that the muscular load imposed on both Short and Tall subjects was significantly greater than that imposed on the Medium subjects. In addition, the Medium subjects’ perceptions of the Standard workstation dimensions support the fact that this workstation was better suited to users with “average” morphologies. The responses elicited in the Personalised and Wrist Support workstations were improved significantly when compared to the Standard workstation. Joint angles were more natural, upper trapezius EMG was reduced, standard of performance improved and perceptual responses indicated a diminished incidence of body and visual discomfort, as well as greater perceived satisfaction with these workstation dimensions. The improved physical responses suggest a decrease in the risk of developing cumulative trauma disorders. Although subjects were unaccustomed to the wrist support device, this workstation demonstrated a further reduction in the range of wrist angles, as well as a general positive attitude towards the concept.

O problema de balanceamento de linhas de produção e designação de trabalhadores (ALWABP, do inglês Assembly Line Worker Assignment and Balancing Problem ) é uma extensão do problema simples de balanceamento de linhas na qual os tempos de execução de tarefas são dependentes dos trabalhadores. Este problema tem sua motivação prática oriunda de linhas de produção com trabalhadores deficientes. Neste trabalho, focamos em uma extensão para o problema que permite lidar com a possibilidade de layouts de linhas com estações em paralelo. Além disso, estudamos uma segunda variante do problema que permite que os trabalhadores colaborem uns com os outros em uma mesma estação. Apresentamos formulações matemáticas para ambas as versões do problema. Adicionalmente, a partir de adaptações de métodos existentes para o ALWABP serial, desenvolvemos heurísticas construtivas para o ALWABP paralelo e ALWABP colaborativo. Testes computacionais em instâncias da literatura e uma análise detalhada dos resultados são apresentados / The assembly line and worker assignment balancing problem is an extension of the classical simple assembly line balancing problem where task execution times are workerdependent. This problem is motivated by the situation faced when balancing assembly lines with disabled workers. In this study, we focus on an extension for the problem with the goal of including the possibility of having layouts with parallel workstations. We also study a second variation for this problem that allows workers collaborating with each other. We present mathematical formulations for both problems. Moreover, constructive heuristics are developed, based on heuristic methods for the serial assembly line worker assignment and balancing problem. Computational tests on literature instances and a detailed analysis of the results are reported

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MEDUSA (Materials and Electronic Devices Universal System Analyzer) is a computer controlled automated workstation capable of conducting eight different experiments, under different independent parameters, and plotting twenty-eight different graphs representing basic semiconductor diode and transport characteristics. This thesis discusses the methodology of computer automation, and the development of the MEDUSA experimental test station. MEDUSA is divided into four different sections: a controlling batch file, a parameter selection routine (PARAMETER), an experimental running routine (RUNIT), and a data manipulation/plotting routine (GRAPHICS). MEDUSA conducts these eight experiments (capacitance and conductance versus time, voltage, current versus voltage, van der Pauw, and four-point resistivity) over a temperature range of 10-600K, with minimal operator interaction. The graphics routines, using elemental semiconductor equations, process the data, and plots high quality graphs suitable for publication. Device and material results are shown to substantiate the validity of this automated system. / Master of Science

Thesis (MScPhysio)--Stellenbosch University, 2015 / ENGLISH ABSTRACT: Background: The use of computers at school, university, work and for social media is growing and whilst neck pain is common in the general population, computer users have an even higher prevalence. Incorrect workstation ergonomics have been identified as a risk factor for the development of neck pain in computer workers. Aims: To assess the effect of adjusting chair and monitor height of a female office worker’s computer workstation on work related neck and upper back pain intensity, comfort of her sitting posture and disability. Methods: An N=1 study was conducted using the A-B-C design consisting of a computer workstation adjustment involving chair and monitor height of a female office worker. The effect of the intervention was evaluated using the Visual Analogue Scale (VAS) to measure neck and upper back pain intensity and comfort of sitting position, and the Neck Disability Index to measure disability. The effect of the intervention was assessed over the three phases, consisting of four weeks each. During these phases, the participant could continue with her usual computer work. The results were compiled and tabulated. Results: A reduction in neck and upper back pain intensity as well as an increase in sitting comfort position were found. However these improvements were not statistically or clinically significant. The effect size for pain intensity was 0.76 and for sitting comfort 0.21. The participant reported no disability as measured by the Neck Disability Index, at the start and at the end at the end of the study. Conclusion: The vertical adjustment of this female office worker’s chair and monitor height according to her anthropometrics improved neck and upper back pain intensity and comfort of sitting position. This ergonomic workstation intervention could form part of a practical management option for computer users with neck and upper back pain. Further research is recommended to establish whether these findings are generalizable to the wider community of computer users. / AFRIKAANSE OPSOMMING: Probleemstelling: Die gebruik van rekenaars by skole, universiteite, werksplekke en vir sosiale doeleindes neem toe. Nek pyn kom dikwels in die algemene bevolking voor, maar dit is meer prevalent in rekenaargebruikers. ‘n Werkstasie wat nie ergonomies korrek opgestel is nie, is geidentifiseer as ‘n risikofaktor vir die ontwikkeling van nekpyn in rekenaar werkers. Doelwitte: Om te bepaal of aanpassings in die stoel- en beeldskerm hoogte van ‘n vroulike kantoor werker se rekenaar werkstasie, ‘n effek het op werksverwante nek en boonste rug pyn, sitgemak en funksionele vermoë. Methode: Die N=1 studie met ‘n A-B-C ontwerp is onderneem en het bestaan uit n rekenaar werkstasie aanpassing waarby die hoogte van die stoel en beeldskerm van ‘n vroulike relenaargebruiker aangepas is. Die effek van die intervensie is ge-evalueer deur middle van die visueel analoogskaal (VAS) om pyn en sitgemak te bepaal; en die Nek Ongeskiktheids Indeks (NOI) om gestremtheid te bepaal. Die effek van die intervensie is oor drie fases, wat elk bestaan het uit vier weke, evalueer. Gedurende die fases, kon die deelnemer met haar gewone rekenaarwerk voortgaan. Die resultate is saamgestel en getabuleer. Resultate: Daar was ‘n vemindering in die intensiteit van nekpyn, boonste rug pyn en die sitgemak van die individu het ook verbeter. Hierdie verbeteringe was egter nie statisties of klinies betekenisvol nie. Die effek grootte vir pyn intensiteit was 0.76 en vir sitgemak was 0.21. Die deelnemer het geen gestremdheid gerapporteer, soos gemeet met die NOI met aanvangs van die studie of teen die einde van die studie nie. Gevolgtrekking: Die vertikale hoogte-aanpassing van die stoel en beeldskerm van hierdie vroulike rekenaar werker volgens haar antropometrie het bygedra tot ‘n verbetering in nek en boonste rug pyn, asook sitgemak. Hierdie ergonomiese werkstasie intervensie kan deel vorm van die praktiese hantering van nek en boonste rug pyn in rekenaargebruikers. Verdere navorsing wod aanbeveel om te bepaal of hierdie bevindinge veralgemeenbaar is na die wyer gemeenskap van rekenaarverbruikers.

O problema de balanceamento de linhas de produção e designação de trabalhadores é uma extensão do problema simples de balanceamento de linhas onde os tempos de execução de tarefas são dependentes dos trabalhadores. Este problema tem sua motivação prática oriunda de linhas de produção com trabalhadores com deficiência. Nesta tese de doutorado estudamos duas extensões para o problema: a primeira layouts de linhas com estações em paralelo, enquanto que a segunda possibilita o uso de múltiplas linhas. As extensões fora aplicadas tanto ao problema básico quanto para o problema de rotação de tarefas. Apresentamos formulações matemáticas e métodos exatos e heurísticos para todos os casos. Teste computacionais em instâncias da literatura e novas instâncias e uma análise detalhada dos resultados são apresentados. / The assembly line worker assignment and balancing problems is an extension of the simple assembly line balancing problem in which the task execution times depend on the assigned workers. This problem draws its practical motivation from assembly lines with workers with disabilities. In this doctoral thesis, we study two extensions for this problem: the first one allows layouts with parallel workstations, while the second one allows multiple parallel lines. These extensions were applied for the base problem as well as the job rotation problem. We present mathematical formulations and exact and heuristic methods for all cases. Computational tests in instances from literature and new instances and detailed analysis of the results are presented.

With the rapid advances in high-speed network technologies and steady decrease in the cost of hardware involved, network of workstation (NOW) environments began to attract attention as competitors against special purpose, high performance parallel processing environments. NOWs attract attention as parallel and distributed computing environments because they provide high scalability in terms of computing capacity and they have much smaller cost/performance ratios with high availability. However, they are harder to program for parallel and distributed applications because of the issues involved due to their loosely coupled nature. Some of the issues to be considered are the heterogeneity in the software and hardware architectures, uncontrolled external loads, network overheads, frequently changing system characteristics like workload on processors and network links, and security of applications and hosts. The general objective of this work is to provide the design and implementation of a JavaTM-based, high performance and flexible platform i.e. a framework that will facilitate development of wide range of parallel and distributed applications on networks of heterogeneous workstations (NOW). Parallel and distributed application developers are provided an infrastructure (consisting of pieces of executable software developed in Java and a Java software library) that allows them to build and run their distributed applications on their heterogeneous NOW without worrying about the issues specific to the NOW environments. The results of the extensive set of experiments conducted have shown that Safran is quite scaleable and responds well to compute intensive parallel and distributed applications.