A statistical analysis of Cape Town wind profile

Abstract The increased integration of wind power into electric power systems presents new challenges for effective planning and operation of these systems. The Weibull distribution is a widely used distribution, especially for modelling the random variable of wind speed. In this respect, the authors present a comparative analysis of a number of methods used for estimating Weibull parameters. Results for a real-world database are presented in a case study format. The techniques require historical wind speed data, collected over a particular time interval, to establish the parameters of wind speed distribution for a specific location, namely Cape Town, South Africa

Characteristics of a Family with the MEN-2A Syndrome

Results of screening and follow-up in a family with the MEN-2A syndrome are described. Fourteen (83%) subjects at risk were affected with medullary thyroid carcinoma (MTC). Asymptomatic pheochromocytoma and parathyroid hyperplasia were found in two instances each. Intrathyroidal MTC without metastases was found in the four youngest subjects and was associated with normal basal but abnormal pentagastrin-stimulated calcitonin (CT) levels. In the ten subjects with abnormal basal CT levels, metastatic spread to at least regional lymph nodes was found. In eight of these ten subjects, total thyroidectomy with excision of affected lymph nodes and additional radioiodine did not return CT levels to normal postoperatively. In the other two subjects, the CT levels returned to normal after thyroidectomy and an ablative dose of radioiodine, and remained normal during follow-up. This study confirms the view that family screening at a young age promotes the detection of MTC at a curable stage. Radioiodine as an adjunct to surgery may be of value in the prevention of tumor recurrence in patients with normal postoperative CT levels but residual thyroid tissue

Postural Control Disturbances Produced By Exposure to HMD and Dome Vr Systems

Two critical and unresolved human factors issues in VR systems are: 1) potential "cybersickness", a form of motion sickness which is experienced in virtual worlds, and 2) maladaptive sensorimotor performance following exposure to VR systems. Interestingly, these aftereffects are often quite similar to adaptive sensorimotor responses observed in astronauts during and/or following space flight. Most astronauts and cosmonauts experience perceptual and sensorimotor disturbances during and following space flight. All astronauts exhibit decrements in postural control following space flight. It has been suggested that training in virtual reality (VR) may be an effective countermeasure for minimizing perceptual and/or sensorimotor disturbances. People adapt to consistent, sustained alterations of sensory input such as those produced by microgravity, and experimentally-produced stimulus rearrangements (e.g., reversing prisms, magnifying lenses, flight simulators, and VR systems). Adaptation is revealed by aftereffects including perceptual disturbances and sensorimotor control disturbances. The purpose of the current study was to compare disturbances in postural control produced by dome and head-mounted virtual environment displays. Individuals recovered from motion sickness and the detrimental effects of exposure to virtual reality on postural control within one hour. Sickness severity and initial decrements in postural equilibrium decreases over days, which suggests that subjects become dual-adapted over time. These findings provide some direction for developing training schedules for VR users that facilitate adaptation, and address safety concerns about aftereffects

Lean system implementation strategy and knowledge framework

Current research has exposed the fact that organisations in South Africa grapple with the implementation of lean systems. Lean systems affect the entire organisation and require strategies which link core and supporting processes from end-to-end. In many cases it requires the redesign of the supply chains’ supporting activities or processes that provide added value to the business processes of the organisation. Contemporary research postulates that to be successful, an organisation should have specific objectives when implementing a lean system. The objectives would ensure a smooth, rapid flow of materials and or work through a system. Primarily it compels management to perform a health-check or business capability performance gap analysis before attempting to formulate a lean implementation strategy. The objective of the paper based on topical research, is the development of a health-check. In developing a knowledge framework and measurement model, various tools were used for statistical analysis. The framework would assist organisations in identifying critical success factors during the implementation of lean. It addresses lean implementation strategy confirming the overall business improvement endeavour through value adding activities. An added advantage is that it would assist an organisation in performing a capability performance health-check before embarking on a lean or value adding project

Critical success factors for Six Sigma Design and deployment to compliment lean operational strategy towards Capability Maturity

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Business processes capability and performance : a South African perspective

Successful organisations depend on leadership, process optimisation, and utilisation of resources. Optimisation is achievable through well-defined systems and supporting processes that guide organisations towards excellence. Organisations need to understand operational and individual business processes as well as the strategic impact on the supply network. Effective optimisation impacts strategically on quality cost, revenue, investment, and capabilities. Business Process Capability measurements forces organisational leaders, managers and employees to critically analyse existing business processes, and determine gaps identifying existing performances and sub-optimal states. Many organizations in South Africa misunderstand business process capability and measure success on revenue and profits generated hiding inefficiencies that could be concealed by the profits. One of the contributing factors might be that some companies in South Africa lack international competitiveness, do not optimize their business processes nor align business processes and available resources to adhere to organizational goals and calls for radical redesign of business processes resulting from end-to-end fulfilling internal and external customer needs. The paper will show why organisations should base their competitiveness on a value chain and end - to - end business processes optimisation rather than only profit

Lean agility implementation and process optimisation decisions

Organisations face many challenges in their battle to survive in the current economic climate. A major challenge facing an organisation is the need to change and change rapidly to remain competitive. This imperative to change can be categorised as a key to survival. A major change agent in the current economic climate is the optimisation of resources and business processes. Consequently, optimisation has become an essential part in the strategy for survival. An important prerequisite in achieving optimisation is the elimination of waste and as a result adding value to business processes, products and services companywide. Recent research postulates that to be successful, organisations must implement strategies to boost process optimisation objectives that achieve customer satisfaction and competitiveness. This paper explores and investigates the interrelationship between lean agility implementation and process optimisation decisions. It particularly focuses on the impact of lean application in terms of speed, flexibility, reliability, quality and cost in an attempt to create value to survive and attain customer satisfaction

An integrated process framework for engineering endeavours

With the exponential increase in the complexity of modern products, the enterprise which creates the product also increases in complexity. Projects to realise engineering products are often fraught with delays, budget overruns and unsatisfied clients. The study sets out exploring the domains of systems engineering, project management and quality management, by extensively referencing industry standards and international good practice in the quest of unravelling conflicts and uncertainties. Selected concepts and business processes of each domain are studied to arrive at an understanding of the objectives and scopes of those processes. This understanding enables the integration of these business processes and concepts by utilising the widely‐used plan‐do‐check‐act (PDCA) cycle. The business processes of each domain are divided into the four PDCA quadrants and integrated models of those quadrants are presented. The four quadrants are synthesised into a single framework which shows the project management, quality management and systems engineering processes performed during a single project phase. This Engineering Management Framework may be tailored for the design and realisation of any complex product, given adequate planning, understanding of the challenges and knowledge of the subject matter

Tree biomass equations from terrestrial LiDAR : a case study in Guyana

Large uncertainties in tree and forest carbon estimates weaken national efforts to accurately estimate aboveground biomass (AGB) for their national monitoring, measurement, reporting and verification system. Allometric equations to estimate biomass have improved, but remain limited. They rely on destructive sampling; large trees are under-represented in the data used to create them; and they cannot always be applied to different regions. These factors lead to uncertainties and systematic errors in biomass estimations. We developed allometric models to estimate tree AGB in Guyana. These models were based on tree attributes (diameter, height, crown diameter) obtained from terrestrial laser scanning (TLS) point clouds from 72 tropical trees and wood density. We validated our methods and models with data from 26 additional destructively harvested trees. We found that our best TLS-derived allometric models included crown diameter, provided more accurate AGB estimates (R-2 = 0.92-0.93) than traditional pantropical models (R-2 = 0.85-0.89), and were especially accurate for large trees (diameter > 70 cm). The assessed pantropical models underestimated AGB by 4 to 13%. Nevertheless, one pantropical model (Chave et al. 2005 without height) consistently performed best among the pantropical models tested (R-2 = 0.89) and predicted AGB accurately across all size classes-which but for this could not be known without destructive or TLS-derived validation data. Our methods also demonstrate that tree height is difficult to measure in situ, and the inclusion of height in allometric models consistently worsened AGB estimates. We determined that TLS-derived AGB estimates were unbiased. Our approach advances methods to be able to develop, test, and choose allometric models without the need to harvest trees