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Citrus black spot (CBS) caused by Guignardia citricarpa is responsible for economic losses in Southern African countries such as South Africa, Mozambique, Swaziland, Zimbabwe and Namibia. Black spot is considered to be a phytosanitary disease for the European Union and the United States of America markets. Exporters to these countries incur losses throughout the supply chain due to phytosanitary restrictions. For these reasons, the occurrence and management practices of CBS and its impact on growers in Southern Africa were investigated through a survey using a questionnaire. In the study, it was found that when CBS was present it was primarily managed by using chemicals and general orchard sanitation. In addition, growers in some of the surveyed countries or production regions follow spraying programs that are based on disease forecasting models and this practice has proven very effective in managing the disease. Furthermore, furfural, a sugarcane waste product was assessed for its efficacy in controlling G. citricarpa. The efficacy of the product as a contact or a fumigant was demonstrated in vitro and in vivo on fresh leaves, leaf litter and fruit lesions as well as in soil. A molecular study, using a Polymerase Chain Reaction protocol was conducted to assess the survival of the pathogen in the soil after exposure to furfural. The product however only proved efficient under natural conditions. The non-target effect of furfural on the soil micro-flora was also assessed. The product proved suitable for soil applications as it is not phytotoxic and has minimal non-target effects on bacterial populations. Furfural proved to control G. citricarpa, by breaking the life cycle, thus reducing the disease incidence. The application of furfural on a larger scale (irrigation or spraying) will therefore improve the control of CBS in developing countries. / Dissertation (MInstAgrar)--University of Pretoria, 2008. / Microbiology and Plant Pathology / unrestricted

This thesis examines the relationship between spot prices, futures prices, and ending stocks for storable commodities. We used Granger causality and DAGs to determine causal relationships and cointegration tests to determine long-run relationships. We use VAR/VECM and consider innovation accounting techniques to see how volatility in one market affects the price behavior and volatility in the other market. Results suggest that for agricultural commodities, innovations in futures price permanently increase the level of spot prices while accounting for much of spot price variance over time. For national oil, shocks to futures price decrease the level of spot price in the long run. In regional oil markets, there are transitory impulse responses. Futures price plays a small role in the volatility of spot prices for oil over time. Overall results are mixed, with oil suggesting futures markets may have a price stabilizing effect and agriculture commodities indicating spot price destabilization.

This report is a summary of the development of sensor integration for low-cost crash avoidance for over-land commercial trucks. The goal of the project was to build and test a system composed of low-cost commercially available sensors arranged on a truck trailer to monitor the environment around the truck. The system combines the data from each sensor to increase the reliability of the sensor using a probabilistic data fusion approach. A combination of ultrasonic and magnetoresistive sensors was used in this study. In addition, Radar and digital imaging were investigated as reference signals and possible candidates for additional sensor integration. However, the primary focus of this work is the integration of the ultrasonic and magnetoresistive sensors. During the investigation the individual sensors were evaluated for their use in the system. This included communication with vendors and lab and field testing. In addition, the sensors were modeled using an analytical mathematical model to help understand and predict the sensor behavior. Next, an algorithm was developed to fuse the data from the individual sensors. A probabilistic approach was used based on Bayesian filtering with a prediction-correction algorithm. Sensor fusion was implemented using joint a probability algorithm. The output of the system is a prediction of the likelihood of the presence of a vehicle in a given region near the host truck trailer. The algorithm was demonstrated on the fusion of an ultrasonic sensor and a magnetic sensor. Testing was conducted using both a light pickup truck and also with a class 8 truck. Various scenarios were evaluated to determine the system performance. These included vehicles passing the host truck from behind and the host truck passing vehicles. Also scenarios were included to test the system at distinguishing other vehicles from objects that are not vehicles such as sign posts, walls or railroads that could produce electronic signals similar to those of vehicles and confuse the system. The test results indicate that the system was successful at predicting the presence and absence of vehicles and also successful at eliminating false positives from objects that are not vehicles with overall accuracy ranging from 90 to 100% depending on the scenario. Some additional improvements in the performance are expected with future improvements in the algorithm discussed in the report. The report includes a discussion of the mapping of the algorithm output with the implementation of current and future safety and crash avoidance technologies based on the level of confidence of the algorithm output and the seriousness of the impending crash scenario. For example, irreversible countermeasures such as firing an airbag or engaging the brakes should only be initiated if the confidence of the signal is very high, while reversible countermeasures such as warnings to the driver or nearby vehicles can be initiated with a relatively lower confidence. The results indicate that the system shows good potential as a low cost alternative to competing systems which require multiple, high cost sensors. Truck fleet operators will likely adopt technology only if the costs are justified by reduced damage and insurance costs, therefore developing an effective crash avoidance system at a low cost is required for the technology to be adopted on a large scale.

The diploma project is involved in structure design of multipurpose house. It´s four floor building with one underground floor and flat roof. Structure system is reinforced concrete skeleton. Ceilings are solved as reinforced concrete slabs, spot supported by columns with circuit reinforcing beam.

The main goal of the diploma thesis is a proposal of alternative metal sheets joining technology which would replace the current technology of spot welding. Different variants have been proposed, and the one which suits the most, the technology of clinching, was compared to the existing one. The costs have been calculated and following results have been concluded: the return of investment of clinching press is about 2 years. In the case of handheld tongs it is 1 and a quarter of a year. Annual savings of clinching press are 234 485 Kč, and in the case of handheld tongs are 258 019 Kč.

In recent years two new diseases, brown spot and black pit, have been observed on potatoes in South Africa. Brown spot symptoms appear on the foliage as small brown lesions, whereas black pit symptoms appear on the tubers as small dark sunken lesions. In this study the causal organism of brown spot and black pit of potatoes in South Africa was determined. During initial isolation, one fungus and two bacteria were isolated, which were included in the trial. Only the treatments where the fungal isolate was used in inoculation resulted in the development of brown spot lesions. The causal organism of brown spot and black pit were identified as Alternaria alternata which is consistent with other research. To better understand the spread of Alternaria alternata between the plants and/or tubers a pot trial was conducted. It was observed that when planting an inoculated seed tuber brown spot may develop on foliage. But the daughter tubers harvested from plants infected with A. alternata will not necessarily develop black pit. Daughter tubers are most likely infected by A. alternata during harvesting and black pit lesions develop in high humidity in storage. Cultivar resistance is one of the most important measures in controlling plant diseases. Cultivar susceptibility of thirteen South African potato cultivars (Avalanche, Buffelspoort, BP1, Fabula, Fianna, Frodo, Hertha, Labadia, Lanorma, Mondial, Pentland Dell, Up-To-Date and Van Der Plank) was evaluated. Pot trials showed that all the evaluated cultivars are susceptible to infection by Alternaria alternata. Various crops (tomatoes, cabbage, mustard, wheat, oats, tobacco and maize) were assessed to determine the host range of Alternaria alternata (potato pathotype) in rotation crops in South Africa potato growing regions. Of the crops evaluated, the pathogen was able to infect only tomato crops. Only wheat, maize and oats can safely be used in the crop rotation in South Africa, as various potato pathogens attack cabbage, mustard and tobacco plants. This study will lead to a better understanding of brown spot and black pit diseases of potatoes in South Africa and globally. The study emphasise the need for further research which will help to reduce brown spot and black pit diseases of potato. / Dissertation (MSc Agric)--University of Pretoria, 2013. / gm2014 / Microbiology and Plant Pathology / unrestricted

Framträdande luftmaktsteorier förefaller i regel vara skrivna av stormaktsföreträdare. Ett implicit antagande att dessa teorier förutsätter betydande militär kapacitet och sofistikerad teknologi gör att de uppfattas som ”stormaktsteorier” som likt en klubba slår hårt mot motståndaren, med begränsad relevans för mindre stater som saknar stormakternas omfattande resurser. Luftmakt finns dock också i länder som kan betraktas som småstater. Även småstater kan – teoretiskt – antingen enskilt eller i en småstatsallians genom välriktade nålstick också skapa strategisk effekt med befintliga resurser.   Denna studie utmanar antagandet att luftmaktsteorier kan betraktas som antingen stormakts- eller småstatsteorier. Genom att pröva Robert Papes luftmaktsteori och Shaun Clarkes SPOT-paradigm i såväl stormakts- som småstatsperspektivet på ett gemensamt fall, Georgienkriget 2008 mellan Ryssland och Georgien, skapas ny kunskap om förklaringskraften hos respektive teori. Studien visar att Papes luftmaktsteori kan förklara stormakters användning av luftmakt, men belägg saknas för att den också kan förklara småstaters luftmaktsanvändning. Vidare saknas belägg för att Clarkes SPOT-paradigm kan förklara vare sig småstaters eller stormakters användande av luftmakt i det aktuella fallet. Däremot visar analysen att SPOT-paradigmet förutsätter ett visst mått av kvantitet och kvalitet, även hos småstater, för att omsättas i en skarp operation. Då ett mått på detta inte ges, bör SPOT-paradigmet främst betraktas som ett förhållningssätt till hur strategisk effekt kan skapas med tillgängliga resurser.

This diploma thesis deals with the problem of the criminalistic method of on-the-spot examination of the testimony, namely with particular questions of its theoretical definition as well as selected questions concerning its practical use within the activities of law enforcement authorities. The overall aim of this thesis is to give a comprehensive view of this institute and to present a detailed analysis of individual aspects of this method of forensic practice, as well as the subsequent identification of particular questions, problems and uncertainties that arise in this context. The first part focuses on the theoretical perspectives of the on-site examination of the testimony. Attention is brought to its process of constitution in Czechoslovak forensic science, its conceptual definition as well as differentiation from other methods of forensic practice. The second part of this thesis deals with selected practical questions related to the on- site examination of the testimony. In addition to the basic tactical principles elaborated by forensic theory, a substantial part of this chapter is devoted to the legal aspects of the on-site examination of the testimony, i.e. its legal regulation, its incorporation into the criminal justice system and possibilities of its use. This part also contains a...

As the demand for electricity increases throughout the globe while we want to reduce the use of fossil fuels, the need for renewable energy sources is bigger than ever. In countries where solar power makes up a large part of the total energy production, the overall electricity spot price level has become lower. This thesis investigates the underlying mechanism that drives the energy market, and in specific, how the solar power impacts the electricity spot price. We present results from studies made in other markets, and introduce a Regime Switching model for explaining the impact in Sweden. We show that an increase of photovoltaics power has a price lowering effect on the daily price pattern in price area SE3 and SE4.