Airborne Wind Energy Systems (AWES) harness the power of high-altitude winds using tethered planes or kites. Continuous and reliable operation requires that AWES become autonomous devices, but the wind intermittency forces the system to repeatedly take-off to start, and land to shut-off. Therefore, a common approach to facilitate the operation is implementing Vertical take-off and landing (VTOL) functionality. This thesis models and simulates AWES flights working towards the implementation of flight controller hardware and autonomous operation of an AWES demonstrator platform. The Ardupilot open-source autopilot platform provides a convenient tool for modeling, simulation, and hardware implementation of small-scale airplanes. An AWES lab-scale demonstrator was developed to obtain operational insight, get preliminary flight data, and real-world experience in this technology. A quadplane was developed by combining a structurally reinforced glider with VTOL and autopilot components. Its performance is obtained from static and aerodynamic studies and converted into the Ardupilot parameter format to define it in the simulation. An AWES flight model was developed from the ground up to evaluate the performance of a simple flight controller in trajectory tracking. The Ardupilot Software-in-Loop (SIL) tool expands the simulation capabilities by running the flight controller code without requiring any hardware. This allowed controller tuning and flight plan evaluation with a more advanced fight model. AWES crosswind flight simulation was only possible due to the incorporation of an elastic tether and an ideal winch into the physics model. As a result, different trajectories and configurations were tested to find the optimal parameters that were uploaded to the flight controller board. The operational capabilities of the AWES demonstrator were expanded with a flight testing campaign. By targeting individual objectives, each test gradually increased its complexity and ensured that the flight envelope was safely expanded. The results were validated with the simulation before moving on to the next flight test. The testing campaign is still underway due to challenges and limitations presented by the legal and logistical aspects of operating the quadplane. However, preliminary flight tests in VTOL mode have been completed and were consistent with the simulated results in terms of autonomous waypoint navigation and attitude control. / Graduate

This dissertation considers the possible influence of the Consumer Protection Act 68 of 2008 on the common law obligations of the seller vis-à-vis: 1) risk and duty to take care, 2) eviction and 3) defects. Before one can have a look at the influence of new legislation on the common law, it is necessary to first go backward to look at where it all started in order to understand any possible influence. In the first chapter there is therefore a historical overview of the common law in general as well as the law of contract. Reference is also made to the Roman law perspective as well as the Roman concept of contract; the Roman-Dutch law perspective as well as the Roman-Dutch concept of contract; and the South African law perspective as well as the South African concept of contract. In chapter 2 the common law and the law of contract is discussed in general with reference to concepts such as ownership, law of obligation, and the emptio venditio. Chapter 3 deals with the essence of this dissertation as we look at the common law obligations of the seller and in specific the risk and duty of the seller to take care of the thing sold until it is handed over to the buyer (factors that influence the duty to take care, passing of risk, and passing of risk in sales by way of consignment); the seller‟s warranty against eviction (including the obligations of the buyer when there is a threat of possible eviction); and the seller‟s warranty against latent defects (ex lege warranties, ex contractu warranties, the actio empti and the aedilitian actions). In chapter 4 there is a very short discussion on the influence of the Constitution of South Africa, 1996 in general as well as specifically on the law of contract. Chapter 5 deals with the influence of the Consumer Protection Act 68 of 2008 in general, specifically on the law of contract (why an Act to protect the interests of consumers?) and then the influence on risk and the seller‟s duty to take care of the thing sold (the consumer‟s right to return goods; the supplier‟s obligation to draw potential risk of an unusual character or that the consumer could not reasonably be expected to be aware of or that could result in serious injury or death to the attention of the consumer), the influence on the seller‟s warranty against eviction (the consumer‟s right to assume that the supplier is entitled to sell the goods; sections 44 and 51) and the influence on the seller‟s warranty against latent defects (disclosure of reconditioned or grey market goods; quality of goods). The conclusion follows in chapter 6. / Dissertation (LLM)--University of Pretoria, 2012. / Mercantile Law / unrestricted

We investigated after effects of automation in take-over scenarios in a high-end moving-base driving simulator. Drivers performed evasive manoeuvres encountering a blocked lane in highway driving. We compared the performance of drivers 1) during manual driving, 2) after automated driving with eyes on the road while performing the cognitively demanding n-back task, and 3) after automated driving with eyes off the road performing the visually demanding SuRT task. Both minimum time to collision (TTC) and minimum clearance towards the obstacle disclosed a substantial number of near miss events and are regarded as valuable surrogate safety metrics in evasive manoeuvres. TTC proved highly sensitive to the applied definition of colliding paths, and we prefer robust solutions using lane position while disregarding heading. The extended time to collision (ETTC) which takes into account acceleration was close to the more robust conventional TTC. In line with other publications, the initial steering or braking intervention was delayed after using automation compared to manual driving. This resulted in lower TTC values and stronger steering and braking actions. Using automation, effects of cognitive distraction were similar to visual distraction for the intervention time with effects on the surrogate safety metric TTC being larger with visual distraction. However the precision of the evasive manoeuvres was hardly affected with a similar clearance towards the obstacle, similar overshoots and similar excursions to the hard shoulder. Further research is needed to validate and complement the current simulator based results with human behaviour in real world driving conditions. Experiments with real vehicles can disclose possible systematic differences in behaviour, and naturalistic data can serve to validate surrogate safety measures like TTC and obstacle clearance in evasive manoeuvres.

The research aims at reviewing how mobile phone producers in the EU are approaching individual obsolete phone collection from private households in terms of the information provided on their websites, in addition to the collective schemes that they may be part of for complying with the WEEE Directive. In this study, competitive benchmarking was used to differentiate the accessibility level of take-back offers among the selected producers. The availability of the take-back offer and the penetration rate in the EU states are examined into a five-level metrics. The results reveal that producers have extreme offers on the availability aspect and diverging information coverage in different countries. It is inferred that a producer’s attitude toward the product take-back affects the accessibility of their take-back offers, which can be explained by several economic concerns; however, different methods in future research is needed to further investigate the reasons behind different producers’ choices.

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Bakgrund: Det ställs höga krav på anestesisjuksköterskor i samband med extubation, de ska klara av att ge en säker vård, kommunicera med sitt team samt bedöma patientens alla mätvärden och riskfaktorer. Att extubera innebär alltid en risk och kan leda till komplikationer för patienten.  Syfte: Syftet med studien var att beskriva anestesisjuksköterskans erfarenheter vid svårigheter av extubation.  Metod: En kvalitativ metod användes och tolv semistrukturerade intervjuer utfördes. Det insamlade datamaterialet analyserades med kvalitativ innehållsanalys baserat på Graneheim och Lundman.  Resultat: I analysen framkom sex subkategorier som resulterade i tre kategorier. Dessa var praktisk och mental handlingsberedskap som innefattade hur anestesisjuksköterskan förberedde sig inför extubationsmomentet. Andra kategorin upplevelse av svår extubation beskriver hur anestesisjuksköterskan kände trygghet i erfarna kollegor samt hur de med tiden utvecklade ett professionellt lugn. Sista kategorin teamarbete belyste att rak och tydlig kommunikation främjade ett bra samarbete. Som övergripande tema framträdde att vara beredd på det oväntade, plötsligt händer det. Slutsats: Svårigheter med extubation är relativt ovanligt, därför behövs tydligare riktlinjer som anestesisjuksköterskan kan vända sig till vid extubationssvårigheter. Simuleringsövningar kan vara ett hjälpmedel för att tryggare kunna hantera komplexa extubationer. För att upprätthålla patientsäkerheten samt få hjälp vid kritiska moment beskrevs att en rak och tydlig kommunikation behövdes på sal vilket även främjade ett gott samarbete. / Background: High demands are placed on the nurse anesthetists during extubation, they must be able to provide safe care, communicate with the team and assess all the patient's measurement, readings and risk factors. Extubation always involves a risk and can lead to complications for the patient.  Purpose: The purpose of the study was to describe the nurse anesthetists experiences with difficulties of extubation.  Method: A qualitative method was used and twelve semi-structured interviews were conducted. The collected data material were analyzed with qualitative content analysis based on Graneheim and Lundman.  Results: In the analysis, eight subcategories emerged which resulted in three categories. These were ability to take action practically and mentally which included how the nurse anesthetist prepared for the extubation moment. The second category, experience of difficult extubation, describes how the nurse anesthetist felt safe in the company of experienced colleagues and how they developed a professional calm over time. The last category teamwork highlighted that straight and clear communication promoted good cooperation. As a theme to be prepared for the unexpected, suddenly it happens emerged.  Conclusion: Difficulties with extubation are relatively uncommon, therefore clearer guidelines are needed to which the nurse anesthetists can turn to in the event of extubation difficulties. Simulation exercises can prepare the nurse in being able to handle complex extubations more safely. In order to maintain patient safety and get help at critical moments, it was described that straight and clear communication was needed in the room, which also promoted good cooperation.

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Food loss and waste (FLW) occurring early in the food supply chain (FSC) leads to increased resource wastage, including land, water, fertilisers, pesticides, fuel, packaging, energy, and labour. Targeting FLW prevention benefits various aspects such as food security, productivity, economic growth, climate change mitigation, resource conservation, and food waste management. Understanding the causes of FLW and their environmental impact is crucial for the design of effective solutions and their prioritisation. The purpose of this study was to investigate the risk factors and underlying causes of FLW in leafy vegetables (LV), mainly lettuce, throughout the Brazilian FSC, spanning from harvest to retail. Additionally, the study evaluated the environmental impact of waste management strategies applicable in the context of the case study. To achieve this, the research methodology encompassed a case study conducted among small-scale producers and retailers in the city of Tupã, Brazil. A comprehensive approach was adopted by integrating a systematic literature review of global FLW causes and those specific to the Latin American context. This approach was complemented by exploratory research, involving interviews with various stakeholders along the FSC, coupled with rigorous root-cause analysis. Moreover, the study employed a Life Cycle Assessment (LCA) methodology to offer an immersive perspective, determining the environmental implications associated with different approaches to treating lettuce waste in the case study. Findings revealed that the root causes of FLW in the case study encompassed normalised unfair trading practices, notably take-back agreement (TBA) conditions, and the absence of supportive policies and incentives for FLW reduction. These root causes manifested in the absence of formal agreements between retailers and local producers, leading to the return of unsold or substandard items without compensation. Furthermore, supermarkets exert power over product quality but evade responsibility for proper storage or encouraging the utilisation of unsold products. Another category of significant causes, designated by the author as "major causes," encompassed causes such as unpreparedness for adverse weather conditions, lack of skilled labour, and stringent visual quality standards. These factors were pivotal risk contributors that potentially motivate various other causes of FLW. To tackle root and major causes of FLW of LV, this study proposed specific measures encompassing fair trade agreements, policy enhancements, protective measures for producers, skill development, and flexible standards. Moreover, by implementing an attributional LCA methodology, the study underscored the importance of source reduction in preventing the environmental impact of food waste for the specific context of the case study. According to the results obtained, for each kg of lettuce that is not produced, 0.065 kg CO2eq are avoided. These findings also highlighted the environmental efficacy of animal feed production, which is a cost-efficient strategy, widely prevalent in the city studied, presents a carbon footprint of -0.013 kg CO2eq/kg of waste. Other common solutions implemented at the case study, such as anaerobic digestion and composting exhibit less favourable carbon footprints, measuring 0.019 and 0.006 kg CO2eq/kg of lettuce, respectively. Landfilling emerges, as expected, as the least desirable option with a considerably higher carbon footprint of 0.423 kg CO2eq/kg. To summarise, this study highlights the environmental advantages of prioritising prevention and higher waste hierarchy levels. It underscores the need for context-specific evaluations when dealing with the intricacies of waste management systems. Moreover, the research emphasises the potential for innovative strategies, multi-stakeholder collaboration, and a holistic approach to address the complex issue of FLW, considering both the environmental impact and practical challenges in a real-world implementation.

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