| 1351. |
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| 1352. |
- Sjöholm, Jennie
(författare)
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Heritagisation, re-heritagisation and de-heritagisation of built environments : The urban transformation of Kiruna, Sweden
- 2016
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This doctoral thesis presents research that aimed to contribute to the understanding of heritagisation in built environments and how heritagisation interacts with structural changes to an environment. The theoretical framework of the research was based on heritagisation, a concept defined by Harrison (2013) as the process through which objects, places and practices are turned into cultural heritage. The research was part of a single case study investigating conceptualisations of built heritage during the urban transformation of the town of Kiruna. Kiruna is a mining town in the northernmost part of Sweden that has plans to be relocated so that the mining company LKAB can continue mining the iron ore deposit that extends underneath the settlement. Kiruna is also a designated heritage site since the 1980s, and includes a large number of protected buildings. Hence, it is of interest how the built heritage is managed during the urban planning process. This is not only because the urban planning situation, which includes the relocation of an entire town, is special, but also because the town’s built heritage inevitably will change during the urban transformation. The research underlying this thesis has followed heritagisation during the urban transformation, from 2004, when the urban transformation was announced, until 2015. The empirical data used consist of planning documents, media reporting and observations, which together provide an overall view of the public discussions over the course of the urban planning process. Findings from the Kiruna case study show that the town’s officially recognised built heritage corresponds with the concept of an authorised heritage discourse (AHD). This heritage discourse was challenged by the urban transformation. Conservation goals are not clearly stated in the urban planning process and there are differing ideas for how to manage historic buildings during the urban transformation. These ideas shift both over time and between stakeholders, and the outcome of the urban planning process depends on a balance between the discourses of heritage conservation, urban development and architectural production. During the urban planning process some parts of the town’s official heritage have been reaffirmed as built heritage, while others have been dismissed. The concept of heritagisation was adopted and developed throughout the research presented in this thesis. This research also introduced the concepts of re-heritagisation and de-heritagisation, which refer to new heritagisation processes that occur when built heritage is contested and challenged during urban change. One of the main conclusions of the research was that the changes in meaning during the heritagisation process can be divided into four dimensions to analyse the complicated relationship between different interests and strategies in urban planning. Heritagisation can refer to: the addition of new heritage; reaffirmation of already designated heritage; re-interpretation of already designated heritage; rejection of previous designated heritage.
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| 1353. |
- Sjøvoll, Jarle
(författare)
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Rom for alle - syn for hver enkelt : studier av implementeringen av individuelle opplæringsplaner i norsk skole
- 1999
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Avhandlingen handler om innføringen av individuelle opplæringsplaner i norsk skole. Avhandlingens epistemologiske forankring er blandet. Den vitenskapsteoretiske orienteringen er i sterkere grad forankret i phronesis enn i episteme selv om jeg forskningsmetodisk relaterer meg til begge begrepene. Avhandlingen er sammensatt av flere delundersøkelser. Resultatene viser at individuelle opplæringsplaner ble innført som ett ledd i omstruktureringen av spesialundervisningen i Norge. Ordningen skulle sikre rettighetene til tilpasset opplæring hos elever med særskilte behov. Det nye er at tiltakene nå kobles sammen med læreplansystemet på en mer formell måte enn tidligere. Ved dette ønsker myndighetene å få bedre styring med spesialundervisningen. I mine delundersøkelser analyseres også ressursbehovet i forbindelse med utarbeidingen av individuelle opplæringsplaner og jeg påviser ulike effekter av dette arbeidet, eksempelvis høyning av lærernes refleksjonskompetanse, øking av "pedagogiske debatter" og at struktureringen av spesialundervisningen endres ved skolene. I avslutnings-kapitlene er det konkludert med at fremtidig spesialpedagogisk tiltaksutvikling i sterkere grad må referere til utvikling av skolen som organisasjon og fokusere på endringsbehov i skolesystemet. Tiltakene må utvikle konteksten for læring.
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| 1354. |
- Skawina, Bartlomiej, 1985-
(författare)
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Load-Haul-Dump operations in underground mines
- 2019
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The research presented in this thesis addresses several aspects of loading operations inunderground mines, in particular tools and equipment selection. It also addresses the flexibilityof the fleet when subject to substantial disturbances, such as ore pass loss, and proposes integration of the scheduling system with discrete event simulation. The thesis begins with a study of discrete event simulation (DES) tools for loading operations in an underground mining system. The results show the benefits of using simulation but also the drawbacks.The thesis presents an analysis of energy consumption and exhaust gas emissions from diesel and electric LHDs. The results show the potential energy savings with the use of electric LHDs. Next, it focuses on the LHD operations affected by long-term ore pass loss (unavailability). It shows the effects on the production system (the ventilation requirements, production and waiting times when too many LHDs operate in the area affected by an ore pass loss) and highlights the need for a flexible solution and a mitigation strategy. Finally, the thesis studies the integration of ABB’s Ability Operations Management System (OMS) with the SimMine simulation model and how this affects LHD operations. The results show the benefits of using the joined platformas a testbed and decision support system.
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| 1355. |
- Skog, Johan
(författare)
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Characterization of sawlogs using industrial X-ray and 3D scanning
- 2013
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- In the Nordic countries, sawlogs are typically sorted upon arrival at the sawmill based on species and dimension. By processing batches of logs with similar size, the sawing process becomes more efficient; the need to change sawing pattern between individual logs is reduced, and the handling of sawn goods is simplified, since the number of different dimensions produced simultaneously decreases. However, since wood is a biological material with great heterogeneity, there will be a large variation in the properties also of boards sawn from logs of similar size. This means that a significant amount of the boards may be carrying unwanted combinations of dimension and grade, so called off-grade products. The problem with off-grade products may be addressed before sawing by the selection of suitable sawing patterns for each log, i.e., using the right logs for the right products. This requires knowledge of the internal quality of the log before sawing. Some information can be obtained from the outer shape measured by an optical three-dimensional (3D) scanner and more detailed information can be obtained using an X-ray log scanner. Today, the use of X-ray log scanners is becoming increasingly common, and most sawmills installing an X-ray scanner already have a 3D scanner present. This raises the question of possible benefits from combining the X-ray and 3D scanning techniques. In this thesis, a method is presented whereby the outer shape of the log measured by a 3D scanner is utilized to estimate the X-ray path lengths through the wood. This converts the X-ray images into green density images of the log, which may in turn be used to calculate quality variables such as heartwood diameter, dry density, moisture content and presence of top rupture. The methods have been tested on Scots pine (Pinus sylvestris L.) and Norway spruce (Picea abies (L.) Karst.) sawlogs using X-ray scanners with one or two measurement directions. The developed methods show a great improvement in precision compared to calculations based on uncompensated X-ray images, and most of the algorithms presented in the thesis have now been implemented in industrial scanner software and are ready for use at the sawmills. This will give the sawmill industry new possibilities to control the production of special products where heartwood diameter and density are important and will lead to less waste and improved profitability for the sawmills.The thesis also describes a method where X-ray scanning is utilized to automatically perform parts of the log grading for payment. This method can improve productivity in the sawmills by remedying a severe bottleneck in the production chain. An authorization of this method for semiautomatic log grading for payment is expected to further increase the industry’s interest in X-ray scanning.
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| 1356. |
- Skogsberg, Kjell
(författare)
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Seasonal snow storage for space and process cooling
- 2005
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The world’s cooling demand has increased considerably during the last decades due to increased population, industrialisation, comfort demands, electronic equipment usage and new building technologies. Conventional cooling is often produced by electrically driven devices. One less prime energy-consuming alternative is to use stored winter cold in snow and ice for cooling during the summer. This ancient technique is feasible in large parts of the world. Different systems for seasonal snow and ice storage exist, i.e. the snow/ice can be stored indoors, on the ground, in the ground and underground. This study focuses on in ground storage, in an open pond, where the cold energy is extracted by water that is cooled by direct contact with the snow. Open pond snow storage must be thermally insulated; hence, different insulation alternatives were discussed. Cutter shavings were studied in laboratory experiments and numerical modelling. The surface melt rate of snow covered with cutter shavings increased with increased solar radiation, air velocity, air temperature, and decreased insulation layer thickness. The evaporation rate contributed significantly to the energy balance. The surface melt rate was similar with initially wet and initially dry wood chips. It was concluded that evaporative cooling is an important part of the thermal insulation qualities of wood chips. It was also found that heat transfer from the rain and ground is usually relatively small. The heat transfer from the ground depends on soil and groundwater properties. The Sundsvall Regional Hospital snow cooling plant in Sweden has successfully operated since 1999. Natural and artificial snow is stored in a slightly sloping, shallow pond of watertight asphalt. During these years, the plant has delivered the main part (77-93%) of the cooling, totalling 655-1,345 MWh. The snow was thermally insulated by a 0.1-0.2 m layer of wood chips. The total coefficient of performance, including construction energy, was 2.0-6.6 times greater than that of a conventional chiller system. The environmental impact of a snow cooling plant and a chiller system was compared, for both existing and “environmentally optimised systems”. Of the existing systems, the chillers had the largest impact concerning climate change, acidification and nitrification, while the snow cooling system meant more photochemical ozone emissions. The dominating impact sources of the snow cooling system were fuel and electricity. In the construction phase, ground insulation had the greatest impact. In future open pond storage, a more compact design (deeper storage) is suggested to reduce maintenance and melt loss. Total cooling costs were estimated to be 0.29-0.47 SEK kWh-1 for a new open pond storage, i.e. lower than that of district cooling. The study also comprised mass loss of freezing water, since repeated freezing and thawing during the spring will evaporate large amounts of water. This was estimated to have little effect on Swedish snow storage, though the loss might be considerable at other locations.
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| 1357. |
- Skär, Lisa
(författare)
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Barn och ungdomar med rörelsehinder : deras uppfattningar om roller, relationer och aktiviteter
- 2002
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The general aim of this thesis was to describe how children and adolescents with restricted mobility perceived their roles, relations and activities in relation to peers and adults in different settings. The thesis includes six sub-studies, which are based on interviews, observations and field notes with children and adolescents with restricted mobility aged from 6 to 19 years. Using Bronfenbrenner’s theory “the Ecology of Human Development” as the main theoretical framework, the ambition was to understand the children and adolescents’ social world from their perspective. The principal finding was the lack of peers in the children and adolescents’ social network. Furthermore, this tendency of isolation from peers was found to increase during the transition from childhood to adolescence. Their relationships to peers were strained and activities and surroundings in which social contacts could develop were limited. The relationships with peers were also characterised by social barriers in the form of attitudes that resulted in social isolation from the group of persons the disabled children and adolescents most wished to be with. When relations to peers were limited, the disabled children’s social life was restricted to adults. The results further showed that the children and adolescents’ roles and relations often were significantly different from their peers. The children and adolescents’ arrived at a concept of themselves that differed from the way others conceptually saw them. Furthermore, the children and adolescents saw themselves as regular members of their peer group, but the other members of the peer group saw them as different from themselves. Relationships to friends of the same age either were confined or were nonexistent. Relationships to adults were often characterised as ambivalent or asymmetric, i.e. the adults were helpful and supportive while over protective and dominant at the same time. The thesis revealed that, despite the many obstacles facing them, the children and adolescents with restricted mobility had a positive view of their future.
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| 1358. |
- Slapak, Rikard
(författare)
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O+ heating, outflow and escape in the high altitude cusp and mantle
- 2013
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The Earth and its atmosphere are embedded in the magnetosphere, a region in space dominated by the geomagnetic field, shielding our planet as it acts to deflect the energetic solar wind. Even though the atmosphere is protected from direct interaction with the solar wind it is indirectly affected by significant magnetosphere-solar wind interaction processes, causing constituents of the upper atmosphere to flow up into the magnetosphere. The fate of the atmospheric originating ions is interesting from a planetary evolution point of view. If the upflowing ions in the magnetosphere are to escape into the solar wind they need to not only overcome gravity, but also the magnetic forces, and therefore need to be energized and accelerated significantly. The subject of this thesis is analysis of oxygen ions (O+) and wave field observations in the high altitude cusp/mantle and in the high latitude dayside magnetosheath of Earth, investigating magnetospheric processes behind ion heating, outflow and escape. Most data analysis is based on observational data from the Cluster satellites, orbiting the Earth and altitudes corresponding to different key regions of the magnetosphere and the immediate solar wind environment. The mechanism behind O+ heating mainly discussed in this thesis is energization through interactions between the ions and low-frequency waves. The average electric spectral densities in the altitude range of 8-15 Earth radii are able to explain the average perpendicular temperatures, using a gyroresonance model and 50% of the observed spectral density at the O+ gyrofrequency. Strong heating is sporadic and spatially limited. The regions of enhanced wave activity are at least one order of magnitude larger than the local gyroradius of the ions, which is a necessary condition for the gyroresonance model to be valid. An analysis indicates that enhanced perpendicular temperatures can be observed over several Earth radii after heating has ceased, suggesting that high perpendicular-to-parallel temperature ratio is not necessarily a sign of local heating. This also explains why we sometimes observe enhanced temperatures and low spectral densities. We also show that the phase velocities derived from the observed low frequency electric and magnetic fields are consistent with Alfvén waves. Outflowing ions flow along magnetic field lines leading downstream in the magnetotail, where the ions may convect into the plasma sheet and be brought back toward Earth. However, the effective heating in the cusp and mantle provides a majority of the O+ enough acceleration to escape into the solar wind and be lost, rather than entering the plasma sheet. The heating can actually be effective enough to allow outflowing cusp O+ to escape immediately from the high altitude cusp and mantle along recently opened magnetic field lines, facilitating a direct coupling between the magnetospheric plasma and interplanetary space. Observations in the shocked and turbulent solar wind (the magnetosheath) reveals hot O+ flowing downstream and approximately tangentially to the magnetopause and often close to it. An estimated total flux of O+ in the high-latitude magnetosheath of 0.7 ·1025 s-1 is significant in relation to the observed cusp outflows at lower altitudes, pointing to that escape of hot O+ from the cusp and mantle into the dayside magnetosheath being an important loss route.
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| 1359. |
- Smirnova, Maria
(författare)
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Long-term observations of polar mesosphere summer echoes using the ESRAD MST radar
- 2011
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Polar Mesosphere Summer Echoes (PMSE) are strong radar echoes observed from altitudes of 80-90 km in polar regions, during summer time. PMSE are closely related to the fascinating atmospheric phenomenon known as noctilucent clouds (NLC). Since it has been suspected that NLC could respond to climate change in the mesosphere, they have attracted considerable interest in the scientific community during recent years. However, continuous visual or photographic NLC observations suffer from weather restrictions and the human factor. In contrast, PMSE radar measurements can easily be made over a long interval and are very attractive for long-term studies of the atmospheric parameters at the polar mesopause. This thesis uses the world’s longest data set of PMSE observations made by the same radar at the same place. Since 1997 these measurements have been carried out with the 52 MHz ESRAD MST radar located near Kiruna in Northern Sweden. The data set for 1997-2008 has been used for studies of diurnal, day-to-day and year-to-year variations of PMSE. We showed that PMSE occurrence rate and volume reflectivity on a daily scale show predominantly semidiurnal variations with the shape of the diurnal curves remaining consistent from year to year. We found that day-to-day and inter-annual variations of PMSE correlate with geomagnetic activity while they do not correlate with mesopause temperature or solar activity. We did not find any statistically significant trends in PMSE occurrence rate and length of PMSE season over 1997-2008. The thesis also presents also a new, independent calibration method, which can be used to estimate changes in transmitter output and antenna feed losses from year to year (for example due to changes of antenna configuration) and allows making accurate calculations of PMSE strength. This method is based on radar-radiosonde comparisons in the upper troposphere/lower stratosphere region simultaneously with PMSE observations. Using this calibration we calculated the distribution of PMSE strength over magnitudes; it varies from year to year with the peak of the distribution varying from 2×10−15 to 3×10−14 m−1. We found that inter-annual variations of PMSE volume reflectivity strongly correlate with the local geomagnetic k-index and anticorrelate with solar 10.7 cm flux. We did not identify any significant trend in PMSE volume reflectivity over 1997–2009. Finally, using 11 years of measurements, we calculated in-beam the PMSE aspect sensitivities using the FCA technique. We showed that half of PMSE detected each year cannot be explained by isotropic turbulence since they are highly aspect sensitive echoes. The distribution of these echoes remains consistent from year to year with median values of aspect sensitivity from 2.9 to 3.7°. The remaining half of the PMSE have aspect sensitivity parameters larger than 9-11°. We found that PMSE aspect sensitivity has altitude dependence: the scatter becomes more isotropic with increasing height. We did not identify any dependence of PMSE aspect sensitivity on backscattered power for any year. We analysed limitations of the in-beam and off-zenith beam methods and concluded that the former is suitable for highly aspect sensitive echoes while the latter is needed for more isotropic scatterers.
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| 1360. |
- Soleimanmeigouni, Iman, 1988-
(författare)
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Predictive Models for Railway Track Geometry Degradation
- 2019
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Railways are a vital and effective means of mass transportation and play a vital role in modern transportation and social development. The benefits of the railway compared to other transportation modes are a high capacity, high efficiency and low pollution, and owing to these advantages, railways are nowadays experiencing a higher demand for the transportation of passengers and goods. This is in turn imposing higher demands on the railway capacity and service quality. As a result, infrastructure managers are being driven to develop new strategies and plans to fulfil new requirements, which include a higher level of resilience against failure, a more robust and available infrastructure, and cost reduction. This can be achieved by making efficient and effective maintenance decisions by applying RAMS (reliability, availability, maintainability, and safety) analysis and LCC (life cycle cost) assessment.A major part of the railway maintenance burden is related to track geometry maintenance. Due to the forces induced on the track by traffic, the railway degrades over time, causing deviations from the designed vertical and horizontal alignment. When the track geometry degrades to an unacceptable level, this can cause catastrophic consequences, such as derailment. Maintenance actions are used to control the degradation of the track and restore the geometry condition of the track sections to an acceptable state.With the current advancements in the field of technologies for railway track geometry measurement, a large amount of event data and condition monitoring data is available. Such technologies, along with advances in predictive analytics, are providing the possibility of predicting the track geometry condition in support of a predictive maintenance strategy. The aim of the research conducted for this thesis has been to develop methodologies and tools for the prediction of railway track geometry degradation, in order to facilitate and enhance the capability of making effective decisions for inspection and maintenance planning. To achieve the purpose of this research, literature studies, case studies and simulations have been conducted.Firstly, a literature review was performed to identify the existing knowledge gaps and challenges for track geometry degradation modelling and maintenance planning. Secondly, a case study was conducted to analyse the effect of tamping on the track geometry condition. By considering the track geometry condition before tamping as the predictor, a probabilistic approach was utilised to model the recovery after tamping interventions. Thirdly, a two-level piecewise linear framework was developed to model the track geometry evolution over a spatial and temporal space. This model was implemented in a comprehensive case study. Fourthly, a data-driven analytical model was developed to predict the occurrence of track geometry defects. This model enables infrastructure managers to predict the occurrence of severe isolated geometry defects. Finally, an integrated model was created to investigate the effect of different inspection intervals on the track geometry condition.
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