| 1. |
- Anderberg, Staffan, 1981-
(författare)
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A study of process planning for metal cutting
- 2009
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Process planning as a function for competitiveness is often neglected. However, as an intermediary between product development and manufacturing, it holds a key function in transforming product specifications and requirements into a producible process plan. Demands and requirements should be met concurrently as manufacturing costs and lead times are minimised. The focus of this thesis is the act of process planning, where the use of better methodologies, computer-aids and performance measurements are essential parts. Since process planning has the function of transforming demands and requirements, changing customer and regulative requirements are vital to regard. Since environmentally benign products and production increases in importance, the research presented in this thesis includes a CNC machining cost model, which relates machining costs to energy consumption. The presented results in this thesis are based on quantitative and qualitative studies in the metal working industry. This thesis has contributed to an enhanced understanding of process planning to achieve better performance and important areas for improvements. Despite a 50 year history of computerised process planning aids, few of these are used in the industry, where manual process planning activities are more common. Process planning aids should be developed around the process planner so that non-value adding activities, such as information management and documentation are minimised in order to allow more resources for value adding activities, such as decision making. This thesis presents a study of systematic process planning in relation to perceived efficiency. This correlation could however not be verified, which opens up for further studies of other possible explanations for process planning efficiency. Process planning improvements in the industry are difficult to make, since there is little focus on process planning activities and limited knowledge about actual performance hereof. This means that measures taken regarding process planning development are difficult to verify.
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| 2. |
- Johansson, Helena, 1971-
(författare)
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Mathematical Reasoning in Physics Tests : Requirements, Relations, Dependence
- 2013
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- By analysing and expanding upon mathematical reasoning requirements in physics tests, this licentiate thesis aims to contribute to the research studying how students’ knowledge in mathematics influence their learning of physics. A sample of physics tests from the Swedish National Test Bank in Physics was used as data, together with information of upper secondary students’ scores and grades on the tests. First it was decided whether the tasks in the tests required mathematical reasoning at all and if they did, that reasoning was characterised. Further, the relation between students’ grades and mathematical reasoning requirements was examined. Another aim in this thesis is to try out if the Mantel-Haenszel procedure is an appropriate statistical method to answer questions about if there is a dependence between students’ success on different physics tasks requiring different kinds of mathematical reasoning. The results show that 75% of the tasks in the physics tests require mathematical reasoning and that it is impossible to pass six out of eight tests without mathematical reasoning. It is also revealed that it is uncommon that a student gets a higher grade than Pass without solving tasks that require the student to come up with not already familiar solutions. It is concluded that the Mantel-Haenszel procedure is sensitive to the number of students each teacher accounts for. If there are not too few students, the procedure can be used. The outcome indicates that there is a dependence between success on tasks requiring different kinds of reasoning. It is more likely that a student manages to solve a task that requires the produce of new reasoning if the student has solved a task that is familiar from before.
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| 3. |
- Andersson, Anders G.
(författare)
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Simulations and measurements of free surface flow in regulated rivers
- 2010
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Open channel flow near hydropower stations is of interest for both engineering and environmental applications. In this research project Computational Fluid Dynamics simulations of free surface flow in regulated rivers were applied with both fish migration and validation of numerical simulations in focus. In the first paper, numerical simulations has been used to evaluate the flow downstream a hydropower plant with regards to upstream migrating fish. Field measurements with an Acoustic Doppler Current Profiler were performed and the measurements were used to validate the simulations. In the second paper ,simulations on the spilling from a dam were performed and compared to experimental results from a physical scale model. The third paper deals with more in depth analysis of field measurements where the variations in the flow downstream a hydropower plant was examined.
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| 4. |
- Johansson, Helena, 1971-
(författare)
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Mathematical Reasoning : In physics and real-life context
- 2015
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This thesis is a compilation of four papers in which mathematical reasoning is examined in various contexts, in which mathematics is an integral part. It is known from previous studies that a focus on rote learning and procedural mathematical reasoning hamper students’ learning of mathematics. The aims of this thesis are to explore how mathematical reasoning affects upper secondary students’ possibilities to master the physics curricula, and how real-life contexts in mathematics affect students’ mathematical reasoning. This is done by analysing the mathematical reasoning requirements in Swedish national physics tests; as well as by examining how mathematical reasoning affects students’ success on the tests/tasks. Furthermore, the possible effect of the presence of real-life contexts in Swedish national mathematics tasks on students’ success is explored; as well as if the effect differs when account is taken to mathematical reasoning requirements. The framework that is used for categorising mathematical reasoning, distinguishes between imitative and creative mathematical reasoning, where the latter, in particular, involves reasoning based on intrinsic properties. Data consisted of ten Swedish national physics tests for upper secondary school, with additional student data for eight of the tests; and six Swedish national mathematics tests for upper secondary school, with additional student data. Both qualitative and quantitative methods were used in the analyses. The qualitative analysis consisted of structured comparisons between representative student solutions and the students’ educational history. Furthermore, various descriptive statistics and significance tests were used. The main results are that a majority of the physics tasks require mathematical reasoning, and particularly that creative mathematical reasoning is required to fully master the physics curricula. Moreover, the ability to reason mathematically creatively seems to have a positive effect on students’ success on physics tasks. The results indicate additionally, that there is an advantage of the presence of real-life context in mathematics tasks when creative mathematical reasoning is required. This advantage seems to be particularly notable for students with lower grades.
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| 5. |
- Lindberg, Richard, 1977-
(författare)
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Determination of Antibiotics in the Swedish Environment with Emphasis on Sewage Treatment Plants
- 2006
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Metoder har utvecklats för att kunna bestämma tolv antibiotikasubstanser, vanliga inom human medicin, i miljöprover. Fokus lades på trimetoprim samt substanser från följande grupper: fluorokinoloner, sulfonamider, penicilliner, cefalosporiner, nitroimidazoler, tetracykliner samt makrolider. Vid extraktion användes fast-fas extraktion för vattenprover och ultraljuds-assisterad fast-fas/vätske extraktion för fasta prover. För separering och bestämning användes vätskekromatografi tandemmasspektrometri. Interna standarder nyttjades för att öka noggrannhet och precision. Extraktionsutbyte låg mellan 50% och 100% för vattenfaser och 14% och 100% för fasta faser. Koncentrationer och massflöden bestämdes för antibiotikasubstanser i inkommande och utgående vatten och slam, från fem avloppreningsverk i Sverige, samt i avloppsvatten från ett sjukhus. I sjukhusavloppsvattnet så påträffades ciprofloxacin (en fluorokinolon) och metronidazol (en nitroimidazol) i höga halter (µg/L nivå). Screening-studien vid de fem avloppsreningsverken visade att norfloxacin, ofloxacin, ciprofloxacin och doxycyklin ofta förekom i inkommande och utgående vatten och slam. Trimetoprim och sulfametoxazol påvisades inte i slam men förekom i snarlika koncentrationer i det utgående vattnet relativt det inkommande. I vattenfasen så förekom de sex antibiotikasubstanserna i ng/L nivån och i slam förekom norfloxacin, ofloxacin, ciprofloxacin, och doxycyklin i låga mg/kg nivån. En studie genomfördes där beteendet hos antibiotikasubstanser under avloppsrening studerades. De två fluorokinolonerna, norfloxacin och ciprofloxacin, adsorberade till slam och mindre än 5% av den totala mängd som kommer till avloppsreningsverket påvisades i det utgående vattnet. I slam var motsvarande andel 70%. Resultat från en process som värmebehandlar rötat avvattnat slam antyder att cirka 50% av de två fluorokinolonerna bryts ner. Trimetoprim adsorberade inte till slam och 100% av total mängd återfanns i det utgående vattnet. Teoretiska beräkningar av koncentrationer och massflöden visade god korrelation till kvantitativa resultat. Ökad noggrannhet i beräkningarna fås genom att beakta stabilitet och fasfördelning. Effekten av antibiotikasubstanser i miljön är idag okänd. Resultat från testprotokoll där deras toxicitet bedöms är i många fall irrelevanta. Tester där organismer är kroniskt exponerade av biologiskt aktiva substanser vid låga koncentrationer är få. Dessutom så fokuserar de ej på de stora potentiella effekterna såsom utveckling eller bevaring av resistenta stammar av bakterier i miljön. Ytterligare studier av förekomst, öde och effekt av antibiotikasubstanser i miljön är nödvändiga.
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