The favorable wind recourses in many cold climate regions make them interesting for development of wind farms. However, with the cold climate come drawbacks due to icing. Production losses, fatigue loadings, ice throws and increased noise are some of the more severe issues that have to be addressed. Thus, wind power in cold climaterequires ice detectors both during the prospecting phase in the site assessment and during production for controlling of the turbines. This study aimed to evaluate six ice detector systems and their ability to detect time periods with ice and ice growth. The usability of the detector data for site assessment or controlling of the turbine was also discussed. The tested detectors were: the T 40 series from HoloOptics (HoloOptics), 0872F1 Ice Detector from Goodrich (Goodrich), LID-3300IP from Labkotec (LID), IceMonitor from SAAB Combitech (IceMonitor) and IGUS BLADcontrol from Rexroth Bosch Group (IGUS). Also a combination of the three anemometers Thies 4.3350.00.0000 from Adolf Thies GmbH & Co.KG (Thies), Vaisala WAA252 from Vaisala Oyj (Vaisala) and NRG Icefree3 from NRG Systems (NRG), used for wind measurements, has been analyzed for ice detection purposes. Data from field tests in Åsele municipality in the northern part of Sweden has been processed in MATLAB. Indications of ice and ice growth have been compared between the detectors to see how often they indicate concurrently. The measurements showed that the IceMonitor and the three anemometers indicated the occurrence of ice at the same time most of the time. The detectors with the ability to detect ice growth (Goodrich, LID, T44 and T41, IceMonitor) had a lot fewer concurrent indications. The correspondence between production loss time periods and the IGUS and T41 ice and ice growth indications were also low. Thus it was concluded that periods with ice were possible to find with a decent precision while ice growth and production loss periods were hard to find with any accuracy. The biggest limitation to the detectors’ functionality was the severe icing events that either hindered the detectors from working properly or broke them completely. None of the detectors were recommended for controlling of the wind turbines. If the reliability of the detectors during the more sever icing events could be increase they could however be used for site assessment to give a rough idea of the icing climate. / De gynnsamma vindar som finns i många regioner med kallt klimat gör dem intressanta för utveckling av vindkraftparker. Men med det kalla klimatet kommer nackdelar på grund av isbildning. Produktionsförluster, utmattningslaster, iskast och ökat buller är några av de mer allvarliga problem som måste åtgärdas. Således kräver vindkraft i kallt klimat isdetektorer både under prospekteringsfasen av området och under produktion, för styrning av turbinerna. Denna studie hade som syfte att utvärdera sex isdetektorsystem och deras förmåga att upptäcka tidsperioder med is och istillväxt. Detektorernas användbarhet vid projektering eller kontroll av vindturbiner diskuterades också. De testade detektorerna var: T 40-serien från HoloOptics (HoloOptics), 0872F1 Ice Detector från Goodrich (Goodrich), LID-3300IP från Labkotec (LID), IceMonitor från SAAB Combitech (IceMonitor) och IGUS BLADcontrol från Rexroth Bosch Group (IGUS). Även en kombination av de tre anemometrarna Thies 4.3350.00.0000 från Adolf Thies GmbH & Co.KG (Thies), Vaisala WAA252 från Vaisala Oyj (Vaisala) och NRG Icefree3 från NRG Systems (NRG), som används för vindmätningar, har analyserats för isdetektionsändamål. Data från fältstudier i Åsele kommun i norra delen av Sverige har behandlats i MATLAB. Indikationer på is och istillväxt har jämförts mellan detektorerna för att se hur ofta de visar samtidigt. Mätningarna visade att IceMonitor och de tre anemometrarna för det mesta indikerade förekomst av is samtidigt. Detektorerna med förmåga att detektera istillväxt (Goodrich, LID, T44 och T41, IceMonitor) hade mycket färre samtidiga indikationer. Överensstämmelsen mellan tidsperioder med produktionsbortfall, is (IGUS) och istillväxt (T41) var också låg. Således drogs slutsatsen att perioder med is var möjligt att hitta med en anständig precision emedan istillväxt och produktionsförlustperioder var svåra att hitta med någon större exakthet. Den största begränsningen av detektorernas funktionalitet var de svåra nedisningseventen som antingen hindrade detektorerna från att fungera ordentligt eller förstörde dem helt. Ingen av detektorerna rekommenderas för styrning av vindkraftverk. Om tillförlitligheten på detektorerna under de svårare nedisningseventen förbättras skulle detektorerna dock kunna användas vid projektering för att ge en ungefärlig uppfattning av isklimatet. / Vindforsk III: V-363 project

Since bellyache bush invaded to East Timor it has significantly reduced crop and animal production and consequential loss of income from farm enterprises. Methods of control of bellyache bush chosen should be appropriate to the poor economic position of the farmers. An integrated method of controlling bellyache bush involving slashing combined with mulching and or burning is low cost and is widely used by the Timorese farmers. Although these practices are commonly used to control weeds, there are still many problems that appear in the field during and after weed control. For instance, rapid regeneration of cut stems and production of less fuel than mixed stands to support burning management. / Therefore, the objective of this study is to investigate mechanical control such as cutting stems at different heights and cutting stems at different heights in combination with mulch, handpulling and mulching of small plants and mulching of seedlings. This study also investigates bellyache bush properties as a fuel for burning management in the late dry season to control its infestations. / Mechanical control of bellyache bush plants was undertaken south of Darwin at Acacia (12º45’S, 131º09’E) which has an annual average rainfall of 1588.1 mm and Channel Island (12º33’S, 130º51’E) which has annual rainfall of 1713.9 mm. This study was conducted from January 2007 to February 2008. All bellyache bush plants were cut off at different heights according to treatment 0cm (ground level), 10cm, 20cm, 30cm, 40cm and uncut plants considered as a control. / The results indicated that all cutting treatments achieved 100% mortality under low canopy cover, irrespective of season. While, under high canopy cover bellyache bush plants only achieved 100% mortality if cut at 0cm and 10cm height. Stems cut at 20cm, 30cm and 40cm heights re-sprouted in the dry season. Hand-pulling completely killed small plants while mulching did not. Mulching achieved a partial kill of seedlings however it stimulated seedling emergence in the wet season, irrespective of site. / The use of bellyache bush as a fuel for burning management was studied. The study was undertaken at Channel Island, Acacia and Katherine (14º22’S, 132º09’E). The latter has a mean annual rainfall of 875 mm. All bellyache bush plants in the plot were cut in May. Five 1m x 1m quadrat samples were selected within a 10m x 10m plot to measure wet weight and dry weight for the curing rate calculation. In addition, 15 of the cut stems were randomly selected to measure re-sprouting. From five randomly selected 25cm x 25 cm quadrat samples were taken to calculate the weight of fine fuel (less than 6mm in diameter), medium (6mm-25mm) and coarse (greater than 25mm). Heat yield of fuel combustion of this material was calculated by using a bomb calorimeter (As 10-38.5 leco 350 calorimeters). / The results indicated that cut stems of bellyache bush from a low canopy cover site had 7 percent moisture content while stems from a high canopy cover site had a 66 percent moisture content by the end of the dry season. The proportion of these stems in the site with low canopy cover re-sprouted significantly less than those in the high canopy cover site. The fuel load at bellyache bush monoculture had less fine, medium and coarse fuel compared with tropical savanna fuel. However, results from this study indicated that it had a similar heat yield of combustion to other plants in the tropical savanna. / A study of the use of fire as a control tool for bellyache bush was undertaken at Acacia and Katherine from May 2007 to February 2008. This study was carried out on established plants of bellyache bush. The experiment was undertaken in three 10m X 10m plots at each of the two sites. The experiment consisted of three treatments namely: cutting stems at 30 cm and followed by burning, uncut plants plus burning and unburnt plants considered as a control. Each of 20 pieces of bellyache bush stems were randomly selected for fine 0-6 mm, medium 6-25 mm and coarse 25 mm fuel. All these pieces were weighed before and after fire to calculate fuel consumption. Fire intensity was calculated by using Byram’s fire intensity equation. Fifteen soil temperature sensors were buried under uncut plants before burning. After burning all soil temperature sensors were dug out the temperature read and used to calculate fire temperature. Plant mortality was calculated by counting live bellyache bush plants before and after fire. Seed germination and seed recruitment was calculated by counting all seedlings within five 1m x 1m randomly chosen quadrats. / The results show that fire consumed all bellyache bush stems in the late dry season burning. Fire intensity of bellyache bush fuels was quite low compared to other tropical savanna fuel. Soil temperatures ranged between 54.17ºC to 126.13ºC. All bellyache bush plants were completely killed by the fire treatment, but fire stimulated seedling emergence in the following wet season. It was concluded from the results of the experiments that mechanical control slashing system may provide a suitable fuel for the burning management if cut early in the dry season. By late in the dry season bellyache bush plants cut early in the dry season have a low moisture content are completely cured and able to support fire spread of adequate intensity to destroy the plants.

With the world economy becoming unpredictable, it has become a necessity for businesses to relook at the way they do business. The world has become competitive and companies that aim to become profitable have seen the need to find ways to improve efficiencies and increase productivity to stay relevant. There has been an adoption of strategies that are aimed at improving the efficiencies in companies such as Total Productive Maintenance (TPM). The strategy is aimed at improving equipment efficiencies and increase productivity through the transfer of certain skills from maintenance personnel to operators. The aim is that the operators perform some of the activities that the maintenance people used to do and they do the more complex tasks. By transferring these skills to operators there is constant cleaning, inspections and lubricating of equipment. This frees up time for maintenance people to do planning and other jobs that require time and higher skills levels. The implementation of these activities allows companies to tap into unused capacity that was always hidden by breakdowns and unplanned stops. The process however requires commitment from management and all stakeholders involved in the organisation. There are prescribed implementation processes that can be followed or companies can follow their own processes but the fundamentals of involving people from the onset must be followed. The involvement of stakeholders creates commitment at all levels and in order to sustain this initiative people must be committed to it. The inclusion of the activities transferred from maintenance people to operators, will reinforce the knowledge and habits required from operators and perhaps sustain the initiative. / MBA, North-West University, Potchefstroom Campus, 2015

With the world economy becoming unpredictable, it has become a necessity for businesses to relook at the way they do business. The world has become competitive and companies that aim to become profitable have seen the need to find ways to improve efficiencies and increase productivity to stay relevant. There has been an adoption of strategies that are aimed at improving the efficiencies in companies such as Total Productive Maintenance (TPM). The strategy is aimed at improving equipment efficiencies and increase productivity through the transfer of certain skills from maintenance personnel to operators. The aim is that the operators perform some of the activities that the maintenance people used to do and they do the more complex tasks. By transferring these skills to operators there is constant cleaning, inspections and lubricating of equipment. This frees up time for maintenance people to do planning and other jobs that require time and higher skills levels. The implementation of these activities allows companies to tap into unused capacity that was always hidden by breakdowns and unplanned stops. The process however requires commitment from management and all stakeholders involved in the organisation. There are prescribed implementation processes that can be followed or companies can follow their own processes but the fundamentals of involving people from the onset must be followed. The involvement of stakeholders creates commitment at all levels and in order to sustain this initiative people must be committed to it. The inclusion of the activities transferred from maintenance people to operators, will reinforce the knowledge and habits required from operators and perhaps sustain the initiative. / MBA, North-West University, Potchefstroom Campus, 2015