| 291. |
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| 292. |
- 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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| 293. |
- 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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| 294. |
- 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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| 295. |
- Spegel, Elin, 1982-
(författare)
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Essays on the economic impacts of floods and landslides
- 2018
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This thesis consists of an introduction and four self-contained papers addressing aspects that are important for how the negative societal effects of natural disasters can be handled, using floods and landslides in the Gothenburg region in Sweden as examples. In paper I the valuation of the benefits of reducing the negative effects of floods, namely, property damage, traffic disturbances and water supply security, were analysed, using a choice experiment. To understand what motivates individuals to contribute towards reducing the negative effects of floods, the impact of individual differences in personality traits were also analysed. Data was collected via a web panel, the final sample consisted of 809 responses. The results showed that individuals’ were willing to pay to reduce the societal costs of floods, and that personality traits helped to explain heterogeneity in preferences. People scoring high on the personality trait including empathic and altruistic characteristics increased the individuals’ probability to support policies aimed at reducing the negative impacts of floods. These results indicate that further investments in flood risk reducing measures should be taken and that public support might increase if policy makers emphasize the welfare gained by society as whole, when designing flood management policies. In paper II the preferences for reducing the negative effects of floods, elicited in paper I, were compared to the preferences of public officials involved in flood risk management. Citizens will have to bear the consequences in the future, of decisions made by governments today. Therefore, it can be argued that decisions should reflect citizens’ preferences. By asking citizens and public officials to respond to identical choice-experiment surveys, it was possible to analyse whether priorities and monetary valuations of the negative effects of floods, namely, property damage, traffic disturbances and water supply security, differed. The overall finding was that public officials and citizens preferences were quite similar, and that both citizens and public officials were willing to pay to reduce the negative effects of floods. The results imply that decisions made within the public sector will likely not differ substantially from citizens’ preferences. In paper III the trade-offs between the distributional aspects and aspects of economic efficiency in in four selected European countries compensation systems for damages caused by floods, namely Sweden, England, France and the Netherlands, were analysed. These countries differ in terms of the level of flood risk, influenced by the physical conditions, as well as in philosophical standpoint of what constitutes a just distribution of compensation following a flood. These aspects has come to affect the costs and benefits of the trade-off between availability and affordability on the one hand and incentives to promote economically efficient behaviour on the other. Finally, in paper IV individuals’ valuation of reducing the negative impacts of landslides, namely, impacts on life, impacts on the environment, impacts on infrastructure, and impacts on important societal services, were analysed, using the choice experiment method. We also evaluated whether individuals valuations were sensitive to the level of risk of landslides. Data was collected via a web panel, the final data sample consisted of 504 responses. We found that reducing the risk of landslides had an overall a positive impact on individuals’ utility. The results also showed that individuals’ valuations were sensitive to risk: individuals’ willingness to contribute financially to policy programs aimed at reducing the risk of landslides increased when the probability of landslides increased.
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| 296. |
- Strandkvist, Viktor
(författare)
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Hand grip strength and postural control among individuals with and without Chronic Obstructive Pulmonary Disease : Epidemiological and motion laboratory studies
- 2019
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- BackgroundChronic obstructive pulmonary disease (COPD) is estimated to affect approximately 8%–10% of all adults. The disease is considered to be a heterogenic syndrome with systemic effects, in which comorbidities including cardiovascular diseases, muscle dysfunction and fatigue are common. The majority of all individuals with COPD have mild to moderate disease (Global Initiative for Chronic Obstructive Lung Disease (GOLD) 1-2), and only a third are identified by health care, and this under-diagnosis contributes to a lack of knowledge of COPD in the population. COPD is related to skeletal muscle dysfunction, where muscle weakness, frequently assessed with hand grip strength (HGS), is one of the components. Evidence of postural control limitations among individuals with severe or very severe COPD has been emerging during the last decade. These limitations are partly related to muscle weakness, however, research of the other underlying systems of postural control is scarce, and an increased knowledge is of importance for the prevention of falls.AimThe main objective of the thesis was to increase the population-based knowledge about muscle strength, assessed as hand grip strength, and also postural control among individuals with and without COPD. Another objective was to investigate the value of hand grip strength measurements in relation to lower limb muscle strength and postural control among community-dwelling older adults.MethodsPaper I and II are based on the population-based Obstructive Lung disease in Northern Sweden (OLIN) COPD study. All individuals with obstructive lung function impairment (n=993) and an age- and sex-matched group without (n=993) (COPD and non-COPD) were identified after re-examination of population based cohorts during 2002-04. They (n=1,986) have been invited to recurrent examinations including structured interviews and spirometry. Paper I (n=1011) and II (n=831) include data from examinations during 2009-2010 and 2014, respectively, where measurements of HGS (Paper I & II) as well as assessment of fatigue and physical activity (Paper II) were included. Paper III and IV are based on the population-based Balancing Human and Robot (BAHRT) study. Randomly selected individuals over 70 years of age were invited to participate in a study of postural control aspects, in their homes and at the 2 Human Health and Performance Lab- Movement Science, at Luleå University of Technology. The examinations included a structured interview as well as measurements of postural control and sensory and motor systems including HGS, lower limb strength, proprioception, pressure sensitivity, visual acuity, vestibular function and reaction time. Participants in Paper III consisted of communitydwelling individuals over 70 years of age (n=45). Paper IV consisted of individuals with COPD recruited from both the OLIN COPD study as well as the BAHRT-study (n=22), as well as a control group without airway obstruction from the BAHRT-study (n=34).ResultsIn Paper I, there was no differences in mean HGS between the groups with and without COPD. However, HGS was related to disease severity; HGS was lower among those with severe to very severe COPD (GOLD 3-4) compared to nonCOPD, and HGS was associated with forced expiratory volume during 1 second % of predicted value (FEV1 % predicted) in regression models. Five years later, in Paper II, mean HGS was lower in COPD compared to non-COPD. Further, individuals with COPD and clinically relevant fatigue had lower HGS than those without clinically relevant fatigue, significantly so among men and close to among women. There was no clear association between HGS and level of physical activity. In Paper III, there was a strong and valid model showing association between HGS and lower limb strength, where all tested muscle groups were significantly correlated to hand grip strength. The regression model with HGS and postural control was significant, however, the model was weak. In Paper IV, individuals with COPD had worse postural control than those without COPD, significantly so regarding mediolateral amplitude in quiet stance with eyes open on soft/unstable surface, as well as anteroposterior limits of stability. In the COPD group, mediolateral amplitude was related to eye sight and the burden of tobacco smoking assessed as pack-years. Further, muscle strength associated with anteroposterior amplitude in the limits of stability test.ConclusionsIn the population-based OLIN COPD study in 2009-2010, mean HGS was significantly lower among individuals with severe to very severe COPD (GOLD 3-4) than those without COPD. Five years later, mean HGS was lower among all individuals with COPD (GOLD 1-4) compared to those without COPD, which may indicate altered aging process in COPD. HGS was associated to fatigue among individuals with COPD, while there were no associations between HGS and physical activity. HGS is a valid tool for the estimation of lower limb muscle strength among community-dwelling older adults, however, HGS is not 3 appropriate to use as an estimation of postural control. Postural control was impaired among individuals with COPD and different postural control assessments had different demands on the sensory and motor systems. The burden of tobacco smoking and visual acuity might be important for quiet stance trials with visual input, while muscle strength might be important for the more dynamic limits of stability test. Further research regarding the longitudinal aspects of muscle weakness and postural control among individuals with COPD is needed to gain knowledge for appropriate preventive or rehabilitative interventions.
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| 297. |
- Strömbäck, Ulrica
(författare)
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The second myocardial infarction : A known but different experience
- 2018
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The overall aim of this thesis was to explore the second myocardial infarction (MI) and describe experiences of the second myocardial infarction from the perspectives of patients and personnel in cardiac rehabilitation (CR).This thesis includes four studies. Studies using quantitative method (I, II) and qualitative method (III, IV) were performed. Studies I and II were retrospective cohort studies based on data from the Northern Sweden’s MONICA myocardial infarction registry. A paired design was used. Study I included 1017 participants, and the corresponding figure for Study II was 820 participants. The participants had at least two MI events recorded in the MONICA MI registry from 1990 – 2009 (I) and 1986 – 2009 (II). The two MI events studied were the first and second events. Study III included eight patients who suffered two MIs. The data were collected through interviews about the experience of suffering a second MI. In Study IV, personnel working with CR were interviewed about the experience of working with patients suffering from a second MI and data from study III were used for describing the patients expressed needs during CR. Data were analysed by descriptive and analytic statistics (I, II) and by qualitative content analysis (III, IV).Both men and women had higher risk factor burdens when suffering the second MI compared when they suffered the first MI. Women had a higher risk factor burden at both first and second MI compared with men. Women also suffered the second MI with a shorter time interval than men did (I). The most common symptom reported in men and women at both MI events were typical symptoms. In men, 10.6 % reported different types of symptoms at first and second MI, and the corresponding figure for women was 16.2 % (II). The number of patients with a prehospital delay < 2 hours increased at the second MI. Furthermore, the results showed that patients with a prehospital delay ≥ 2 hours at the first MI were more likely to have a prehospital delay ≥ 2 hours at the second MI (II). Suffering a second MI is a known but different event compared to the first MI, it makes afflicted people realise the seriousness and the importance of making lifestyle changes (III). People express they are more affected after having the second MI, both physically and psychologically (III). In the analysis of congruence between the needs patients expressed linked to CR and personnel’s description of how they worked, a theme emerged: “Be seen as a unique person” 2(IV). The patients expressed a need of customised care, and the personnel described that it was important for them to individualise the care given to these patients.Suffering a second MI is experienced as a different and more serious event that the first one. The patients had gained valuable knowledge due to their previous experience and the second MI was a wake-up call for life style changes. A majority of the patients had typical symptoms at both MI events and an increased number of patients had a prehospital delay < 2 hours at the second MI. We suggest that the personnel in CR pay attention to first-time MI patients’ illness representation to enhance the patient’s awareness of the seriousness of the illness and the fact that they suffer from a chronic illness. The care given after an MI, including cardiac rehabilitation should be person-centred to involve the patient as an active participator in the care and were the patient’s resources and needs are in focus.
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| 298. |
- Sundqvist, Erik, 1985-
(författare)
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Towards systematic improvement work in project-based organizations : An efficiency and effectiveness perspective
- 2018
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Project-based organizations (PBOs) have adopted projects as a primary tool for carrying out most of their operations. By doing so, the PBO operates mainly on two organizational levels, the project level and the organizational level. For these organizations, improving project management (PM) performance is central for the survival of the organization, since PM is considered both a strategic competence and a source of competitive advantage for delivering customer value. For PBOs, prioritizing efficiency has often been described as a short-term focus meeting time and budget targets. The need to shift focus toward value creation in PM is suggested to be of importance to succeed in delivering value to customers. Project performance, and the separate but interlinked concept of project success, can be described using the two concepts of efficiency—doing things right—and effectiveness—doing the right things. However, although commonly used within the field of quality management, the application of these two concepts in the PM literature and practice has proven to be unclear which has implications on organizational improvement.It is through the two concepts, efficiency and effectiveness, that systematic improvement work in PBOs can be understood. This thesis addresses the need for influences from other research fields, by approaching improvement work in PBOs from a quality management perspective. More specifically, the purpose is to advance our understanding of how PBOs can work systematically toward improvements, from an efficiency and effectiveness perspective. This is done by exploring challenges related to improvement work in a PBO operating as a subsidiary to the Swedish minerals group LKAB. In order to do this case study research has been used, including a combination of data collection methods: including semi-structured interviews, participant observations, and document analysis. Case study findings have continually been compared to theory in order to reach conclusions.The findings indicate that an organizational-level improvement process is missing, and that PBOs need to link such a process to project-level processes, in order to work toward improvements. Applying an efficiency and effectiveness perspective further clarifies the division of practice and responsibility between PBO and the client. Further, it is suggested that the role of the project manager as an improvement agent in PBOs should be formalized and clarified, in order to support learning and organizational-level improvement. Finally, the need to clarify and manage what constitutes value and value creation among stakeholders in projects is emphasized, in order to support both efficiency and effectiveness in project work.The thesis contributes to the literature by discussing the prerequisites for PBOs to work toward improvements, and by approaching project management from a quality management perspective. From a managerial perspective the thesis emphasizes the importance of clarifying responsibilities regarding project value creation, as current practice seem to promote a separation of responsibility, in which the PBO is responsible for aspects of efficiency, and the customer is responsible for aspects of effectiveness.
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| 299. |
- Sundqvist, Jesper
(författare)
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Aspects of Heat Flow in Laser Processing of Metals
- 2018
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Since the laser was invented in 1960, its use in manufacturing industry has been growing rapidly. Laser processing of metals is based on the flow of heat that is generated by the absorbed laser beam. One outstanding aspect of laser beams is high precision along with high controllability of energy transfer, which includes creative techniques of shaping the beam and in turn the process. The thesis presents six Papers A-F on different metal processing techniques, namely welding, hardening and cutting, the latter combined with additive manufacturing. For each respective technique it was studied how desired properties can be optimized by controlled use of the laser beam and in turn of the temperature field. Addressing their different complexity of the heat transfer, various theoretical and experimental analysis methods were applied.Laser beam welding is usually conducted with standard beam shapes, i.e. Gaussian or top-hat like, which is not always optimal for the process. Identification of an optimised weld pool shape or temperature cycle could increase the quality of welded products or even enable new applications. Papers A and B aim to increase the knowledge for non-standard beam shapes, particularly for single-pulse conduction mode welding. Paper A presents an investigation on an industrial application where a C-shaped weld joint is desired. The sensitivity to and optimization of different C-shaped beam irradiation profiles is discussed. The analysis is mainly carried out by applying Finite Element Analysis, FEA, to calculate the heat conduction contributions, showing unexpected sensitivity in certain regimes. Paper B presents a semi-analytical model for fast calculation of the temperature field from different beam profiles. Examples include multi-spots or the misalignment sensitivity of Diffractive Optical Elements.In Paper C, for laser hardening of 11% Cr ferritic stainless steel the temperature field was studied to enable hardening. It was shown that single-track hardening without sensitisation could be achieved but overlapping tracks had a continuous network of ditched grain boundaries and is thereby at risk for sensitisation. The sensitised area is caused by a reheating cycle.The same mechanism for the same material was studied in Paper D when applying a recently developed drop deposition technique, where additive manufacturing is fed by laser cutting. The same reheating isotherm becomes critical, but here sensitisation tests show a discontinuous network of ditched grain boundaries in the added material. The solid heat-affected zone on the other hand has a continuous network of ditched grain boundaries, which implies a sensitisation risk. The continuous network is however not in contact with the surface. The tested parameters is thus not at risk for intergranular corrosion through sensitisation.For friction stir welding of dissimilar metals, Ti-6Al-4V with AISI 304L stainless steel, Paper E, the influence of a laser-induced preheating temperature field on the tool forces was investigated through numerical simulation. By suitable application of laser preheating, the forces acting on the tool can be substantially lowered, in a robust manner.The temperature field from seam welding induces a residual stress field. In Paper F, for continuous wave laser keyhole welding of high strength steel butt joints, a method is presented to identify the residual stress behaviour of laser welded sheets by measurement of the fatigue crack growth rate during testing, by deriving the crack acceleration. The analysis was confirmed by hole drilling tests and by FEA.The knowledge and methods of the above different experimental and theoretical studies complement each other. They contribute to further optimize certain aspects through laser-induced temperature fields, for different manufacturing techniques.
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| 300. |
- Sundström, Joel, 1988-
(författare)
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Studies of Transient and Pulsating flows with application to Hydropower
- 2018
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The rotational motion of a hydraulic turbine runner makes pulsating flows ubiquitous in different locations of the machine. The cyclic loading thus induced may generate large pressure forces acting periodically on both stationary and rotating parts. In addition to the presence of pulsating flows in a turbine runner, transient flows are encountered at an increasingly higher rate due to the continual installation of intermittent sources of renewable energy, such as wind and solar power. To mitigate the imbalance that these unpredictable sources induce on the frequency of the electrical grid, hydropower turbines are enforced to regulate their power production, and consequently flow rate, thus leaving them to operate under transient conditions. In terms of wear and fatigue, a startup or shutdown of a hydraulic turbine corresponds to 10-20 hours of steady state operation at the design point. Transient operation of a hydraulic machine can, however, also be used in favour for measuring the discharge through the turbine using the pressure-time method. A better understanding of pulsating and transient flows thus has the potential both to mitigate problems associated with them, and to increase the accuracy with which the turbine flow rate can be measured; two great merits for the hydropower community. In light of this observation, the following work constitutes a fundamental investigation of transient and pulsating flows performed in a straight pipe.Studies have been performed experimentally using particle image velocimetry, hot-film anemometry, laser Doppler velocimetry and pressure sensors.A chief finding is that the time-development of the wall shear stress and near-wall turbulence fields exhibit significant similarity between transient and pulsating flows, despite the different conditions of the mean flow. Whereas the former is initiated from a statistically steady state, the latter is constantly subjected to a time-varying forcing. Both types of unsteady flows have previously been investigated in detail; however, any potential similarity between them has, largely, been unexplored. An important implication of this finding, then, is that knowledge acquired in one type of unsteady flow can be used, if not interchangeably, at least as a guidance for the expected behaviour in the other type of flow. An example is the development of unsteady turbulence models. Another important finding is that the frictional losses arising during the late stage of a pressure-time flow rate measurement can be accurately modelled using an analytical laminar formulation of the wall shear stress, despite the bulk of the flow being turbulent. The formulation of the wall shear stress has potential to be further improved by incorporating a damping-function.
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