The modern painting process in automotive industry is complex and a lot of factors affect the result. The trial and error method is used today to control the quality and introduce new colours. This method takes a lot of time and does not show any clear numbers of how the process is affected by changing the parameters. During this thesis, we have investigated a delimited number of parameters. The work is based on experiments performed on samples that represents a flat surface of the cab, to reduce experimental costs. Our master thesis is done at Scania in Oskarshamn, where all the cabs for the European production is produced. The objectives with this thesis has been to explain how the process parameters of the robotic applicator affect the paint distribution, paint thickness and the colour of the top coat. We also optimised the process by finding which settings gives an even paint distribution, a correct thickness and an accepted colour of the top coat. We have been using Design of Experiments to achieve the goals of this study. Design of Experiments is a statistic method that is used to perform experiments effectively. It also shows the effect of changing the factors from a low to a high level. We have chosen to divide the workflow into three parts: screening, optimisation and confirmation. The experiments are performed during the daily production to replicate the real circumstances. The shape air, paint flow and high rotation is the most important parameters to control. Paint flow also seems to have a linear impact on the thickness of the top coat layer. The Shape air and the high rotation on the other hand mainly affect the distribution of the top coat layer. Different levels are needed for the shape air and high rotation depending on what paint flow is used. The optimal settings of the factors for our colour were found to be paint flow at 82 %, the shape air at 90 %, the high rotation at 90 % and high voltage at 100 %. The optimal settings give a result of 1,535 μm in spread and 40,08 μm in mean thickness. Our settings compared to today’s results contributes to a reduced paint consumption, better quality and therefore less rework.

An abundance of evidence from a wide range of astrophysical and cosmological observations suggests the existence of nonluminous cold dark matter, which makes up about 83% of the matter and 27% of the mass-energy of the Universe. Weakly Interacting Massive Particles (WIMPs) have been one of the most promising dark matter candidates. Various detection techniques have been used to directly search for the interaction in terrestrial detectors where WIMP particles are expected to scatter off target nuclei. Over the last fifteen years, dual-phase time projection chambers (TPCs) with liquid xenon (LXe) as target and detection medium have led the WIMP dark matter search. The XENON dark matter search project is a phased program focused on the direct detection of WIMPs through a series of experiments employing dual-phase xenon TPCs with increasing target mass operated at the Gran Sasso underground laboratory (LNGS) in Italy. The XENON1T experiment is the most recent generation, completed at the end of 2018. The XENON1T dark matter search results from the one ton-year exposure have set the most stringent limit on the WIMP-nucleon spin-independent elastic scatter cross-section over a wide range of masses, with a minimum upper limit of 4.1 x 10⁻⁴⁷ cm² at 30 GeV · c⁻² and a 90% confidence level. XENON1T is the first WIMP dark matter experiment which has deployed a dual-phase xenon TPC at the multi-ton scale, with 3.2 t of LXe used. The large xenon mass posed new challenges in reliable and stable xenon cooling, in achieving and maintaining ultra-high purity as well as in efficient and safe xenon storage, transfer and recovery. The Cryogenic Infrastructure was designed and constructed to solve these challenges. It consists of four highly interconnected systems --- the Cryogenic System, the Purification System, the Cryostat and Cryogenic Pipe, and the ReStoX System. The XENON1T Cryogenic Infrastructure has performed successfully and will continue to serve the next generation experiment, called XENONnT, with a new Cryostat containing a total of 8.4 tons of xenon. I first give an instrument overview of the systems in XENON1T. I then review the cooling methods in LXe detectors which led to the design of the cooling system implemented in the XENON1T experiment, and suggest a design of the cooling system for future LXe dark matter experiments at the 50 tons scale. I describe and discuss in detail the design and the performance of the XENON1T Cryogenic Infrastructure. Finally, I describe the detector stability and the corresponding data selection in all three XENON1T science runs, and describe the dark matter search results from the one ton-year exposure.

Using 641 principles of economics students across four universities, the authors examine whether providing monetary incentives in a prisoner's dilemma game enhances student learning as measured by a set of common exam questions. Subjects either play a two-player prisoner's dilemma game for real money, play the same game with no money at stake (i.e., play a hypothetical version), or are in a control group where no game is played. The authors find strong evidence that students who played the classroom game for real money earned higher test scores than students who played the hypothetical game or where no game was played. Their findings challenge the conventional wisdom that monetary incentives are unnecessary in classroom experiments.

The purpose of this study was to find out if there is a relationship between teacher-learner interactions and laboratory learning environment in Chemistry practicals in Namibia. Literatures and questionnaires from 1383 learners and 12 teachers have proven that the interactions between teacher and learners have great impact on the performance, understanding and the environment that prevail in the laboratory. The main data collection methods used was the mixed method research through the use of questionnaires and interviews. The results from the study show that good teacher-learner interactions have contributed to the positive learning environment that prevails in Namibian schools. Although the majority of the learners especially the girls have negative connotations towards Chemistry in terms of content, calculations and assessment generally learners look forward and are excited to do experiments in practical work. The impact of the excitement and willingness of learners to do practical investigations has not proven to improve learners‘ performance in Chemistry practical work in Namibia. The majority of the learners rated their teachers as good in subject knowledge, good leaders, helpful and friendly during practical investigations. The shortage of chemicals, equipments in laboratory activities that should have inspired involvement of learners in handling equipments is one of the factors that contributed negatively to the learning environment and teacher-learners interactions. Teachers mostly resolve to demonstrations due to lack of chemicals and equipment. Some schools show low/poor level of learner-learner interactions because some learners tease, laugh and discourage others during practical investigations. Chemistry laboratories in Namibia are characterised by lack of equipment, chemicals, poorly behave learners while on the other hand there are good behaviours from the teachers‘ side with most learners showing that their teachers always try to make the best out of the prevailing situations in the laboratories. The laboratory environment in Namibia closely resemble laboratory environment in other studies in Asia, Africa and Europe. From empirical evidence it can be therefore concluded that there is a relationship between teacher-learner interactions and laboratory learning environment in Chemistry practicals in Namibia. Although the relationship is not as harmonious or congruent as it ought to be, the government of Namibia can play a greater role in creating positive, productive and enjoyable learning environment by supplying secondary schools‘ laboratories with the needed equipment and chemicals to support the practical work as stated in the Physical Science syllabi. The three questionnaire used were rated by learners and teacher as effective; easy to understand; covering most areas of the Chemistry environment; not time consuming, statistically valid and consistent. The changes made to the questionnaire fit well to the Namibia Chemistry environment and it produced nearly the same reliability and validity when compared to the pilot study questionnaire and other similar questionnaires used in other country. / Curriculum and Instructional Studies / D. Ed. (Didactics of Education)

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Irrigation is "the artificial application of water to the soil for the purpose of getting large and steady crop yields". It is supplementary to rainfall and the quantity of water applied and the time of application, therefore, must be determined by the character of the rainfall. Irrigation is usually practiced in those regions which have low rainfall as natural precipitation at such places is insufficient to meet the full water requirements of crops.

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