M.Ing. / With an ever-increasing population and a decrease in availability of fresh water, the sustainable and secure supply of fresh water is a growing concern worldwide, and particularly so in South Africa. Plumbing systems have a significant impact on both the efficient use of water and water losses because high quality plumbing components can reduce wastage and leakage, while inferior components increase the risk of failures and leakage and can even have health impacts in case of leaching of toxic elements or contamination of drinking water. In recent years, South Africa has seen a plethora of imported and pirated plumbing components introduced onto the local market. While South African legislation requires that only plumbing components approved by the South African Bureau of Standards or Water Services Authorities (municipalities) shall be installed, it does not explicitly prohibit the importation and sale of non-compliant components. The availability of non-compliant components on the market combined with insufficient enforcement of legislation, have created a situation where many non-compliant components are installed, although the extent of this problem was not known at the start of the project. The study aimed to quantify the extent of non-compliant plumbing components installed in South Africa, as well as the impact this will have on future water demands and losses. Various research methods were used including literature reviews, surveys and interviews with role players, search of available plumbing components for sale in South Africa, on-site visits and analysis of some case studies. The study found that about 50% of plumbing components installed in South Africa do not comply with legal requirements. Because these components are of poor quality, they hurt the local industry whose components cost more in order to comply with SABS standards. Therefore, they suffer from reduced market share and lower profit margins, and South African job losses occur in the sector. In general, compliant Summary components are up to 135% more expensive than non-compliant components. This study also found that even plumbers who are IOPSA members, and therefore bound by a code of conduct to use only compliant components, install non-compliant components. The site visits to some government low-cost housing developments showed that less than 10% of the plumbing components installed were compliant, and a major problem with non-compliant components was leakage. Therefore if the situation does not change, on-site water leaks will remain a great concern in South Africa. In order to address this situation the main suggestions are better enforcement of legislation, better training and control of plumbers and restrictions on the importation of non-compliant components.

The most common management problem associated with irrigated agriculture is knowing when to apply irrigation and how much of it is required. This is termed irrigation scheduling. Despite numerous techniques and tools developed by the scientific community to aid and improve irrigation scheduling, surveys have shown that farmers growing the same crops in the same region use different amounts of water. This is because of low adoption rates of available irrigation scheduling aids and/or their poor application for various reasons ranging from cost, accessibility and simplicity of the methods. So, as part of a WRC funded project on using Wetting Front Detectors, we seek a simple approach that can be used to better manage irrigation using wetting front detectors (WFD). This prototype WFD was developed in Australia, and was designed to be simple so that it can be understood and used by farmers at any level of training. There are two versions; one is electronic called a FullStop and the other is mechanical, called the Machingilana, a sePedi word for a watchman. The mode of operation of this WFD is based on the physical properties of water movement in the soil or a porous media. The tool give a “Yes” or “No” answer to whether the water has penetrated to a specific depth, and that’s all the farmer needs to know to adjust his irrigation amount of interval according to a chosen algorithm. This experiment on wetting front detectors was undertaken at the University of Pretoria experimental station to: (1) Evaluate two different methods of using electronic wetting front detectors, (II) evaluating two different methods of using mechanical wetting front detectors, and (III) to compare the accuracy of the wetting front detector method against the neutron probe and a computer-based irrigation-scheduling model. Six treatments were evaluated. They were referred to as the Machingilana (MACH), crop factor (CF), FullStop 1 (FSI), FullStop 2 (FS2), neutron probe (NP) and Soil Water Balance model (SWB) treatment. The first four treatments used WFDs in different ways to manage irrigation. Lucerne (Medicago sativa, variety WL 525HQ) was chosen as experimental crop. The NP method was used as control treatment, given the acceptance and credibility this method has received from researchers. The aim was to use dry matter production per volume of water used as an indicator of treatment performance. However, it was later discovered that due to the extensive root system of Lucerne, the crop could compensate for either under- or over-irrigation and dry matter yield was not a good indicator of treatment performance. Statistical analysis of the dry matter yield data collected from three cycles revealed that the treatments were not significantly different at a 5% confidence level, although there was great variation in total amount of irrigation applied to each treatment per growth cycle. This is due to the fact that the crop was able to mine into deeper soil layers for water, although this strategy would not be sustainable in the long run without extra irrigation applied. In the light of this, the trend in soil water deficit obtained with the neutron water meter for each treatment was used to evaluate the six treatments. The four treatments based on WFDs (Machingilana, FS1, FS2 and CF) performed comparatively well to the control and SWB model treatments. However, this is not without discrepancies in all the WFD treatments or the control and SWB model treatment, but the problems associated with each treatment’s successes or failures have been outlined, and with follow-up research, those problems can be rectified. It is concluded that WFDs can be valuable, simple and affordable tools to better manage irrigation, provided appropriate guidelines for using them are applied. / Dissertation (MSc (Agriculture))--University of Pretoria, 2005. / Plant Production and Soil Science / unrestricted

No description available.

In-car communication systems (ICCS) are becoming more frequently used by drivers. ICCS are used in order to minimise the driving distraction due to using a mobile phone while driving. Several usability studies of ICCS utilising speech user interfaces (SUIs) have identified usability issues that can affect the workload, performance, satisfaction and user experience of the driver. This is due to current speech technologies which can be a source of errors that may frustrate the driver and negatively affect the user experience. The aim of this research was to design a new multimodal interface that will manage the interaction between an ICCS and the driver. Unlike the current ICCS, it should make more voice input available, so as to support tasks (e.g. sending text messages; browsing the phone book, etc), which still require a cognitive workload from the driver. An adaptive multimodal interface was proposed in order to address current ICCS issues. The multimodal interface used both speech and manual input; however only the speech channel is used as output. This was done in order to minimise the visual distraction that graphical user interfaces or haptics devices can cause with current ICCS. The adaptive interface was designed to minimise the cognitive distraction of the driver. The adaptive interface ensures that whenever the distraction level of the driver is high, any information communication is postponed. After the design and the implementation of the first version of the prototype interface, called MIMI, a usability evaluation was conducted in order to identify any possible usability issues. Although voice dialling was found to be problematic, the results were encouraging in terms of performance, workload and user satisfaction. The suggestions received from the participants to improve the system usability were incorporated in the next implementation of MIMI. The adaptive module was then implemented to reduce driver distraction based on the driver‟s current context. The proposed architecture showed encouraging results in terms of usability and safety. The adaptive behaviour of MIMI significantly contributed to the reduction of cognitive distraction, because drivers received less information during difficult driving situations.

Today’s endeavor of performance and accomplishment might bring more efficiency in many ways, but it has a price. Stress related diseases have increased in numbers the last decades and the field of stress is an exceptionally live issue. Linkura is a company which partly works towards identifying and decreasing stress. To be able to monitor and detect stress in people’s daily life, an ECG-device is used. This thesis is divided into two parts. The first part consisted of analyzing and comparing four different ECG based stress measures. These stress measures were RMSSD, Heart Rate, high frequency (HF) band and ratio between low and high frequency bands (LF/HF), last two based in frequency domain. These were taken from healthy test subjects for periods of relaxation where the stress level presumably would decrease. What could be seen for all measures was that they all showed a statistical significant decrease in stress level (p<0.05) during the relaxation period. LF/HF ratio was the one performing best and showed clearest decrease in stress. Biofeedback is a growing treatment, or rather, health monitoring, which purpose is to gain awareness of physiological functions to manipulate them at will. The second part of the thesis compared two ECG-related respiratory components, to find out which one would be most suited for biofeedback purpose to lower stress in the form of breathing exercises. The two respiratory components investigated were beat to beat heart rate and R-peak amplitude. For this part, a real-time application in the form of a mobile application was created and connected to the ECG-device. This enabled real-time measurement, which was crucial for the second part. Different time and frequency based algorithms were made to compare the two respiratory components. What could be seen was that the beat to beat heart rate signal was the respiratory component following breathing pattern the most.

The development of automated vehicles is something most vehicle manufacturers are working on these days. Different levels of automation allow the driver to perform other tasks while traveling than focus on the dynamic driving tasks. For professional drivers where there are strict laws for the amount of driving hours that is allowed without stopping and taking a break, resting while the vehicle is in an automated driving mode can increase the transport efficiency and the comfort of the driver. With data collected from 11 professional long-haul truck drivers in the ADAS&ME project, the goal of this thesis is to investigate if it is possible to obtain rest during autonomous driving (simulated with a confederate driver). Pre- and post-drive tests, KSS and SUS ratings, HRV features obtained from ECG data and blink features obtained from vertical EOG data was used in order to evaluate if rest could be obtained during simulated autonomous driving compared to normal driving. The results show that no clear trends or statistically significant differences can be seen while comparing simulated autonomous driving with normal driving. However one of the participants showed indications in KSS and SUS ratings together with the HRV features that rest was obtained during the simulated autonomous driving. The results indicate that it could be possible to obtain rest during autonomous driving, but a larger set of participants and a more demanding study setup is needed to verify the impact of autonomous driving as a substitute for regular rest breaks in terms of obtaining rest.

No description available.

To facilitates tasks in modern healthcare, innovative solutions can be used and the product Sippi is an example of this. Sippi is a self-emptying siphon device used for monitoring a patient ́s urine production. This report examines one of the two main components of Sippi, known as the disposable unit. The unit consist of a siphon which is self-emptying without needing any mechanical assistance. The purpose of the report is to understand how some vital components of Sippi affect the emptying rate and determine the optimal length of the outlet tube. Theoretical calculations and experiential methods are used for the investigation. From the data and with help of software from Observe Medical, results could be generated in various forms, leading to several conclusions. The examined components, which were the bell and the filter had a negative effect on the emptying rate, resulting in a decreased rate when in use. Regarding the pressure drop, it was concluded that longer pipes generated greater pressure drop across the pipe. Additional studies are required to establish the ideal length of the outlet tube.

During this project, the risk management of a medical device under development that deals with drug administration has been done. The aim of the project is to evaluate if part of the device is safe according to the current regulations in Sweden. The complexity of the risk management processes, particularly in healthcare, together with the lack of standardised methods to develop these kind of processes leads to a need of new tools to reduce the time, resources and complexity in this stage of the development. That is why two tools have been used and tested in order to assess the suitability under medical device development regulation conditions: the Hazard Ontology (HO) and a Fault Injection System(FIS). HO is a novel tool used to identify all hazards and threads from a predefined system in a structured way. On the other hand, FIS is a testing technique that aims to help with the study of systems when they are under faulty conditions. To ensure that the current regulations in Sweden regarding medical device are fulfilled, the EN ISO 14971 has been used as a guide for the methods applied during the work. The results of the project are exposed for every step of the process. At the end, the main result of the risk management process is a list of the mitigation measures that must be included as safety specifications of the device. Both tools, HO and the FIS, have proofed to be suitable with the current regulations as well as being useful for the process. HO gave as output a list of the main hazards of the system and the FIS have been used in the verification step of the mitigation measures. Three mitigation measures to test with the FIS has been chosen. They deal with faults regarding a speed sensor, a potentiometer and the PWM signal controlling the motor. The mitigation measures have been verified for both PWM signal and the potentiometer faults. However ,a faulty condition that leads to an unsafe behaviour has been found for the speed sensor. Therefore, we demonstrated that the medical system under study has still many control measures to implement, verify or improve before it can be said that it is a safe medical device. / Under detta projekt, har en riskhantering av medicinsk utrustning som hanterar läkemedel gjorts. Målet med projektet är att utvärdera om utrustningen är säker enligt de svenska bestämmelserna. Komplexiteten med riskhanteringsprocessen, speciellt inom sjukvård, tillsammans med brist på standardiserade metoder för utveckling av dessa typer av processer leder till behov av nya verktyg för att minska tiden, resurserna och komplexiteten i detta skede av utvecklingen. Det är därför två verktyg som har använts och testats för att bedöma lämpligheten under de bestämmelserna för medicinsk utrustnings utvecklingsförhållande: Riskontologin (HO) och felinjektionssystem(FIS). HO är en ny metod som används för att identifiera alla faror och hot för ett identifierat system på ett strukturerat sätt. Å andra sidan är FIS en testteknik vars syfte är att hjälpa att studera systemet när det är under felaktiga förhållande. För att försäkra sig att de svenska bestämmelserna rörande medicinsk utrustning är uppfyllda, har EN ISO 1497 använts som en guide för de metoder som applicerats under projektet. Resultatet av projektet är synligt för varje steg av processen. Till slut, är det huvudsakliga resultatet av riskhanteringsprocessen en lista av de mildrande åtgärder som måste vara inkluderade som säkerhetsspecifikation av utrustningen. Båda verktyg, HO och FIS, har visat sig vara lämpliga med nuvarande bestämmelser och användbara för processen. HO gav oss, som data en lista med de huvudsakliga farorna av systemet och FIS användes i verifieringssteget av de mildrande åtgärder. Tre begränsningsåtgärder att testa med FIS har valts.De åtgärdar de fel för hastighetssensor, en potentiometer och PWM signalen som driver motorn. De begränsningsåtgärderna har verifierats för både PWM-signalenoch potentiometerfelen. Emellertid har ett felaktigt tillstånd som leder till ett osäkert beteende hittats. Därmed visade vi att det medicinska system som studeras fortfarande har många kontrollåtgärder för att genomföra, kontrollera eller förbättra innan det kan sägas att det är en säker medicinteknisk produkt.

In this study a structured light prototype device was evaluated for the possible use as a respiratory gating device in PET/CT. The device functions by measuring the movement in the vertical direction of the obtained 3D-surface of the chest and abdomen with the breathing.The aim of the thesis was to evaluate if and in what way a respiratory signal could be measured for patients undergoing a PET/CT examination. The system was verified against a second gating device, Sentinel by C-RAD, for 15 healthy test-persons. A high Pearson correlation coefficient between the two systems was measured indicating a similar performance in the measurement of the respiratory phase, while there were some differences in the measurement of the mean peak-to-peak amplitude between the systems. 42 patients were examined with the device at Akademiska Sjukhuset in order to test if it were possible to measure a respiration signal from the patients in the PET/CT. An useful respiratory signal was obtained for 41 patients. The size of the FOV is large enough to cover two bed-positions in the PET/CT to be respiratory gated. The prototype device has the potential to be used as a respiratory gating device with the possible benefits of having a fully contact-less system. However, improvements of the 3D-surface quality has to be made in order to ensure a constant position of the respiratory gating point, as well as further testing about the ability to measure the amplitude accurate. / I denna studie utvärderades en prototyp av en optisk gating-utrustning som använder sig av strukturerat mätljus för att mäta hur en 3D-yta av bröstet och buken av patienten rör sig vertikalt med andningen. Målet med examensarbetet var att utvärdera om och på vilket sätt en andningssignal kunde mätas för patienter som genomgår en PET/CT undersökning. Prototypen verifierades i tester där den jämfördes mot en annan redan existerande produkt för andningsgating, Sentinel från C-RAD där 15 friska testpersoner var med. Resultatet av testerna var en hög Pearson korrelationskoefficient mellan de två systemen vilket tyder på likvärdig översättning av testpersonernas andningsfas, medan det var skillnader i medelamplituden mellan mätningarna. 42 patienter undersöktes i en klinisk studie med prototyputrustningen på Akademiska Sjukhuset för att testa om det gick att mäta en andningssignal på patienterna när de genomgick en PET/CT undersökning. En användbar andningssignal gick att få fram för 41 av patienterna. Storleken på FOV var stor nog för att täcka de två säng positionerna som ska gateas. Prototypen har potential att användas som en andningsgating utrustning i PET/CT med de potentiella fördelarna att vara ett system helt utan patientkontakt. För att kunna använda systemet måste det däremot utföra förbättringar på kvaliteten på 3D-ytorna för att kunna säkerställa att punkten på ytan för gatingen kan hållas konstant. Dessutom behöver det ske mer utredningar kring utrustningens prestanda för att mäta amplituden.