| 1. |
- Eriksson, Anna, 1985-
(författare)
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Influence of Oxygen Enrichment on the Oxidation of a Magnetite Pellet Bed During Pot Furnace Induration
- 2021
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This study was motivated by the excess oxygen that likely results from the current transition to hydrogen-based Swedish steel production. The potential usability of large amounts of oxygen in a process gas for iron ore pellet induration could improve the process efficiency in terms of fuel consumption and productivity. Iron ore pellets constitute the main raw material used in Scandinavian steel production. Knowledge of the effects of the process-gas oxygen level on induration is a prerequisite for establishing if, how, and to what extent oxygen enrichment can be exploited in an optimum manner to control temperature development and oxidation, while maintaining pellet quality. The objectives of this study are as follows: 1) to investigate the effects of the oxygen level in the inflow gas on pellet bed oxidation during induration, as well as the effects on the bed-scale temperature, oxidation degree, and cold compression strength (CCS) development; and 2) to identify the oxidation mechanisms corresponding to various oxygen levels and thermal histories. The current knowledge regarding the effects of high oxygen levels in the gas on oxidation is based on small-scale experiments; this study was conducted on a larger bed-scale and will thus contribute significantly to the knowledge pool of bed-scale effects resulting from different oxygen levels in the inflow process gas. An interrupted pot furnace experimental method was used, with the highest investigated oxygen level in the gas at 40% and an approximate bed-scale of 100 kg of pellets. The following conclusions were drawn from this study. First, efficient heating and a high degree of oxidation of an entire bed were rapidly achieved with the highest investigated oxygen level (40% O₂) compared to the results of the lower oxygen levels (6%, 13% and 30% O₂). The gas with 40% O₂ yielded improved pellet properties and a more uniform oxidation degree along the bed, compared to beds exposed to gas with lower O₂. Second, the temperature at the bottom of the bed increased more rapidly when exposed to a higher oxygen content in the gas compared to when only the gas temperature was increased. Third, the mechanical pellet properties (CCS and macrostructure) were improved in a bed exposed to gas with 40% O₂ compared to beds exposed to gas with lower oxygen levels. Finally, pellets from local conditions with comparable thermal histories oxidised according to similar mechanisms regardless of the oxygen level. Hence, it was demonstrated that the oxygen level influences the oxidation rate, whilst the temperature affects the oxidation mechanism. The overall trends in terms of the positive effect from the high oxygen content in the gas are promising, as they serve as a starting point for enabling faster production rates in the future.
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| 2. |
- Eriksson, Anna
(författare)
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The effects of endothelin-1 in human adipose tissue
- 2010
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Obesity is a result of an imbalance between energy intake and energy expenditure ending in an excessive accumulation of body fat. Being overweight or obese increases the risk of death because of obesity related complications, e.g. insulin resistance, type 2 diabetes, cardiovascular diseases and some types of cancer. This multifactorial disease is influenced by both genetic and environmental factors and has already reached epidemic proportions. Adipose tissue serves as an energy reservoir and is very important in the regulation of energy homeostasis but it also acts as a secretory organ and as an active signaling tissue. The signaling molecules secreted by adipose tissue modulate metabolism and function of both adipose tissue and other organs in the body which can have a negative impact on health. Obesity and type 2 diabetes are also associated with increased levels of non-esterified fatty acids (NEFAs) in the circulation due to enhanced lipolysis (the enzymatic hydrolysis of triacylglycerides into NEFAs and glycerol). Growing evidence suggests that NEFAs are involved in mediating insulin resistance in these conditions, especially in abdominal obesity. Adipose tissue consists of several other cell types except adipocytes. It is a highly vascularised tissue and thus endothelial cells are present. They release the vascular peptide endothelin-1 (ET-1), an extremely potent vasoconstrictor involved in the regulation of blood pressure but also a multifunctional peptide with cytokine-like activity that can affect several aspects of cell function with both positive and negative effects. A number of studies show that plasma levels of ET-1 are increased in insulin resistance, obesity and type 2 diabetes and that ET-1 might contribute to the development of several metabolic diseases. The majority of studies have concentrated on the role of ET-1 in glucose metabolism while studies assessing the role of ET-1 in lipid metabolism are lacking. The overall aim of this thesis was to study the effect of ET-1 in human adipose tissue. When the present project was started, there were no published studies regarding the role of ET-1 in affecting hormone-stimulated and/or basal lipolysis in human adipose tissue. We set out to study the effect of ET-1 in lipid metabolism in human adipocytes and to try to characterize the signaling pathway. In paper I, we investigated whether human adipose tissue releases the vascular peptide ET-1 and whether it could account for regional differences in the regulation of lipolysis. We confirm that ET-1 levels are increased in obese subjects and that subcutaneous (SC) adipose tissue contributes to an elevated release of ET-1 in vivo in the obese state. ET-1 also attenuates the antilipolytic effect of insulin in omental (OM) but not SC adipocytes after long-term treatment. Our study shows that ET-1 signals via the ETB-receptor (ETBR) and mediates its action by decreasing the protein expression and/or activity of several signaling proteins involved in the antilipolytic pathway of insulin. In paper II, we further investigated the regional expression and cellular origin of ET-1 and its receptors in adipose tissue and whether ET-1 has any effects on basal lipolysis. We observed that ET-1 expression was higher in SC compared to OM fat and that it is released from non-adipocytes within adipose tissue. ET-1 increases basal lipolysis in SC adipocytes after long-term treatment possibly through the ETA-receptor (ETAR) which was also shown to be increased at the protein levels in obese SC adipose tissue. In addition, the effect on basal lipolysis was positively correlated with BMI. In conclusion, ET-1 has a dual effect on lipolysis in adipocytes. In visceral adipocytes it promotes an insulin resistant state where insulin-mediated inhibition of hormone-stimulated lipolysis is attenuated via ETBR. Conversely, in SC cells, ET-1 increases basal lipolysis via ETAR. Both these effects result in an increased release of NEFAs from adipose tissue. It is quite possible that increased ET-1 release via these mechanisms could contribute to the development of insulin resistance and type 2 diabetes in obesity.
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| 3. |
- Eriksson-Gustavsson, Anna-Lena, 1949-
(författare)
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Att läsa : -ett behov, -ett krav, -en nödvändighet : en analys av den första internationellt jämförande studien av vuxnas förmåga att förstå och använda skriftlig information : International Adult Literacy Survey = [Reading] : [-a need, a requirement, a necessity]
- 1997
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This is a presentation and an analysis of the International Adult Literacy Survey, IALS, the first international comparative study of reading ability and reading habits among adults. The study was carried out in seven countries in Europe and North America during 1994 och 1995. It was conducted by Statistics Canada, in cooperation with Educational Testing Service in USA, and OECD in Paris, France. The aim was to bring to a focus the relations between individuals' reading ability, educational level and occupation, and economic growth and development in society. A second aim was to identify groups of individuals who may suffer, socially as well as economically, because of a low level of reading ability.The National Agency for Education was responsible for the Swedish participation in the study. A representative sample of the population, 16 years of age and older, have taken part in the study, which was conducted by means of interviews and objective tests of reading ability.The results demonstrate that there are substantial differences in reading ability among the population both within the country and in comparison with other countries. Education lays the ground for the development of reading ability, but work-related reading and leisure reading both have an impact on further development of the ability.In analysing the Swedish data focus has been on three variables, education, reading ability and reading habits. Individuals with a high educational level demonstrated better reading ability and more frequent reading activities. both at work and in leisure, than did individuals with a lower educational level. Individuals with higher education read more books, visited a library more often and read much more in relation to work than did individuals with lower education.According to the IALS survey, however, approximately one third of the Swedish 16+ population did not reach the level of reading ability that is set in the national curriculum (Lpo 94) as a goal for the end of grade 9 in the Swedish compulsory school.This thesis also contains a pilot study, the aim of which is to test a method of researching adults' reading habits in depth. In the pilot study data were collected by means of reading-diaries. From the diaries it appeared that the time individuals reserved for reading during week days increased substantially from the lowest to the highest level of education. It was the time spent with reading in relation to work that made all the difference. It was also evident that the variation of reading materials was much larger for individuals with a high educational level than for those with a low educational level.The opportunities and possibilities for adults to improve their reading ability vary a great deal. There is every reason to emphasize the need for increased opportunities of recurrent education, in order to avoid a wider and deeper gap between individuals with high and low levels of reading ability. Further research about the context and requirements of adult reading in the future society is also needed.
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| 4. |
- Eriksson, Lars Douglas, 1940-
(författare)
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Kris, alienation och autenticitet i Lev Sestovs filosofi
- 2017
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- In this study of Lev Shestov, the biographical method is used to explain his philosophy. The grave crisis or nervous breakdown Shestov went through caused a total transformation of his - convictions and values. It was probably this drama that led to his repudiation of the common life and traditional philosophy with its emphasis on reason, knowledge, and ethics in favour of an extreme individualism and religious transcendence.The aim of the dissertation is to examine, amongst the great number of philosophers and writers Shestov analysed, mainly those in his view “marginal thinkers”, who were of the greatest interest to him – Fyodor Dostoevsky, Lev Tolstoy, Friedrich Nietzsche, Martin Luther, and Søren Kierkegaard. On the basis of this analysis the character of Shestov’s philosophy is defined.According to Shestov, like his own crisis, the crises that these thinkers experienced occasioned a total transformation of their convictions and values. Šestov does not let his life find complete expression in his philosophy. Instead he projects his crisis into the five thinkers’ crises and philosophy.To characterize the previous and new modes of thinking, the concepts of alienation (degeneration, degradation, depravity) and authenticity (deliverance from alienation) are used. Shestov’s judgment of the consistency of the five thinkers’ new attitudes is presented, i.e. deliverance from the common life with its emphasis on rational eternal truths and moralism. Authentic life is in Shestov’s opinion the from the individual’s everyday life concealed experience of despair in extreme situations. This constitutes a grave crisis that leads to the repudiation of all hitherto held convictions and cherished hopes.The contrast between the Russian philosopher’s personal, (after his crisis) mainly tranquil, harmonious life and his philosophy is glaring.Analyzing the five thinkers, Shestov finds that they did not persevere with their new convictions, instead they complied with the by everybody accepted and everywhere valid truths. Shestov’s “theoretical”, uncompromising and consistent stance on one side and the lack of these characteristics with the aforementioned thinkers on the other side, to a great extent places Shestov in another category than these.In Shestov’s view freedom is in the region of tragedy, which nobody enters on his own will and in the incomprehensible trust in a capricious, “inhuman” God. According to Shestov, only the philosopher, who derives his thinking from a situation, where he experiences extreme despair and hopelessness, can claim to be a true philosopher.
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| 5. |
- Eriksson, Ola, 1979-
(författare)
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Numerical Computations of Wakes Behind Wind Farms
- 2015
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- More and larger wind farms are planned offshore. As the most suitable build sites are limited wind farms will be constructed near to each other in so called wind farm clusters. Behind the wind turbines in these farms there is a disrupted flow of air called a wake that is characterized by reduced wind speed and increased turbulence. These individual turbine wakes combine to form a farm wake that can travel a long distance. In wind farm clusters farm to farm interaction will occur, i.e. the long distance wake from one wind farm will impact the wind conditions for other farms in the surrounding area.The thesis contains numerical studies of these long distance wakes. In this study Large Eddy Simulations (LES) using an Actuator Disc method (ACD) are used. A prescribed boundary layer is used where the wind shear is introduced using body forces. The turbulence, based on the Mann model, is introduced as fluctuating body forces upstream of the farm. A neutral atmosphere is assumed. The applied method has earlier been used for studies of wake effects inside farms but not for the longer distances needed for farm to farm interaction.Numerical studies are performed to get better knowledge about the use of this model for long distance wakes. The first study compares the simulation results with measurements behind an existing farm. Three parameter studies are thereafter setup to analyze how to best use the model. The first parameter study examines numerical and physical parameters in the model. The second one looks at the extension of the domain and turbulence as well as the characteristics of the flow far downstream. The third one gathers information on the downstream development of turbulence with different combinations of wind shear and turbulence level. The impact of placing the turbines at different distances from the turbulence plane is also studied. Finally a second study of an existing wind farm is performed and compared with a mesoscale model. The model is shown to be relevant also for studies of long distance wakes. Combining LES with a mesoscale model can be of interest.
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| 6. |
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| 7. |
- Frost, Anna E., 1988-
(författare)
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Power transfer in the air gap of linear generators for wave power
- 2019
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- An increased need for electric energy and share of renewable energy is important for a more sustainable future, to which wave power can contribute. Some concepts for wave power use linear generators, and the studies presented here focus on the power transfer and forces in the air gap of linear generators.Based on Poynting's theorem, analytical expressions were derived for how much power is transmitted in the air gap of linear electric machines. The equations were derived for flat linear generators as well as for cylindrical linear generators, and for both the radial and the longitudinal power flows. The radial power flow contributes to the electricity that can be taken from the generator, while the longitudinal contributes to unwanted effects such as vibration. The equations show that for flat linear electric machines, vibrations and other unwanted power transmissions can be reduced by increasing the number of poles in the machine, without decreasing the desired power transfer. Otherwise, the same factors that increase the desired power transfer also increase the unwanted.By studying the generator as a damping force and a lumped circuit, it was derived that the absorbed energy of a linear generator is quadratically dependent on the partial stator-translator overlap if the inductance of the generator is not affected by a partial overlap. Consequently, the forces in the air gap also depend quadratically on the relative overlap between the stator and the translator.Data were collected during two experiments in order to determine whether the quadratic dependence between partial stator-translator overlap and energy transfer could be seen experimentally. Linear regression analysis of the experimental data shows that the relationship is somewhere between linear and cubic, but did not clearly show a quadratic relationship. The inductance showed no dependence of the partial stator-translator overlap.
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| 8. |
- Gottlieb, Laura
(författare)
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Designing Tools for Joint Inquiry : Making and thinking together
- 2020
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Positioned within the research program and subject area of Innovation and Design, this research focuses on the relationship between tools and joint inquiry. Joint inquiry – the collaborative exploration and definition of problems and possible solutions – plays an important part in Participatory Design processes. Tools, usually involving the making or using of artefacts in workshops, are developed and used to support joint inquiry between different actors. The aim of this research is to contribute to the deliberate design and systematic evaluation of tools for joint inquiry. This work addresses the literature gap comprising a lack of systematic evaluations in Participatory Design research and a need to evaluate designed activities and environments in relation to emerging designer-participant collaborations.This research is a starting point towards developing a systematic approach for designing tools for joint inquiry and introduces two frameworks for this purpose. The first is the Communities of Inquiry framework, from the field of computer-mediated communication in distance education, which is used to identify indicators in joint inquiry. The second framework is a categorisation used to distinguish different aspects of a tool. Combining the two frameworks aids the understanding of the relationships between tools and indicators for joint inquiry. A Research through Design and Research for Design approach is used to study conversations between people and in interaction with tools. Nine design experiments are described, all of which involve the design and testing of tools to support the initiation of joint inquiry. The tools were primarily created and tested within an academic context with design students and researchers, with a focus on the topic of co-production – that is, close collaboration between academia and external actors. One tool was created and used within a museum with youth and researchers.The results from the design experiments show that the tools supported the Communities of Inquiry indicators in the following ways: eliciting metaphors stimulated humour and encouraged contributions, renegotiating artefacts provoked brainstorming, commensality promoted phatic communication and humour, the relationship between material properties and metaphors prompted problem recognition, and formats directed towards personal experiences led to self-disclosure and emotional expression. The tools were a hinderance to the Communities of Inquiry framework when there was dominant participation and when the tools were considered to be inappropriate for certain work contexts. Future research will continue to develop means of systematically evaluating and designing tools that support communicative practices in Participatory Design processes.
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| 9. |
- Harvey, Frida, 1985-
(författare)
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Kollegialt lärande i matematik : Ett verksamhetsteoretiskt perspektiv
- 2021
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- In the last decade, Professional Learning Communities (PLCs) are increasingly used as models for teachers’ joint efforts in developing their teaching. The overall aim of this licentiate thesis is to expand the knowledge of PLCs in mathematics, by deepening the understanding of aspects that influence the establishment, organization, and implementation of PLCs in mathematics. Specifically, the aim is to contribute with an overview of how PLCs in mathematics are organized and framed, and also to explain what may enable and hinder PLCs in mathematics. To fulfill the purpose, two studies are conducted where Cultural Historical Activity Theory (CHAT) is used as a conceptual and analytical framework. In the first study, previous research of PLCs in mathematics are synthesized through a configurative literature review, resulting in a description of how PLCs in mathematics are organized and framed. In the study, similarities, and differences between different models of PLCs in mathematics are examined regarding subjects, objects, mediating artifacts, rules, community, division of labor and outcomes. The result shows three different activity systems, with different objects or motives for implementing the PLCs. The activity systems vary concerning the use of mediating artifacts, and what norms regulate the activity system, but are similar regarding participants, context, and division of labor. In the second study, contradictions, and their manifestations in PLCs in mathematics are analyzed. Contradictions may enable or hinder the work of PLCs depending on whether they are identified or not. Contradictions, and their manifestations, are in the study examined through interviews with teacher leader coaches with experience in coaching teacher leaders of PLCs in mathematics. In the study, four contradictions, in and between activity systems, are identified. These four contradictions are manifested through 26 conflicts and dilemmas. The identified contradictions are connected to the norms and traditions that are part of mathematics as a discipline as well as the teacher profession. Taken together, the result of the two studies can be useful in establishing, organizing, and implementing future PLC endeavors.
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| 10. |
- Olofsson, Helén, 1965-
(författare)
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Skriftbruk i fordonsverkstaden : En studie av läs- och skrivstrategier i mötet med arbetslivets texter
- 2011
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The aim of the study was to describe the reading and writing activities that takes place in vehicle repair workshops and to elucidate how people experiencing low reading-and-writing ability describe their encounters with text in working life. Reading and writing are considered in the study from an educational-philosophical and special educational perspective. This study of literacy was inspired by ethnographic methods. The empirical material consists of field notes from ten participatory observations in vehicle repair workshops, photographs from the workshops and three interviews. To see patterns in how literacy was used, literacy events were taken as the unit of analysis. The literacy environment, community of practice, reading path and technical surroundings are analytical concepts in the thematic presentation of results. Central literacy practices were characterized primarily by reading, often via computer, for information needed for solving problems. The type of reading was often non-linear, given the multimodal texts and choices in computer environments. In addition, semiotic systems and several languages were interpreted. It is important to understand how information is organised and how to handle the technology. Technology provides support structures e.g. pictorial support and translation programmes. Writing out words, button-pushing and keyboard entry to register and search for information through the use of measurement instruments and in computer-generated text environments, were central. Literacy events were embedded in the work tasks and in ongoing learning, and many literacy practices included items of both reading and writing. Social skills, plus recognizing one’s problems and asking for help, were useful strategies for handling the demands of reading and writing in working life, as were allowing time and creating concentration for the task. Interpreting pictorial matter, using technology, copying text and noting down things to remember were further strategies. Implications of the study are that effective strategies for managing the demands of reading and writing that are required in the working place should begin in school. Significant is the teachers’ approach to handling the students’ frustration when studies are not working out as expected. Caring teachers, positive energy and not giving up make a difference. General education teachers need special educational resources in the upper-secondary school in order to counteract school failure and to enhance students’ learning.
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