| 1471. |
- von Wachenfeldt, Thomas
(författare)
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Folkmusikalisk utbildning, förbildning och inbillning : En studie över tradering och lärande av svensk spelmansmusik under 1900- och 2000-talen, samt dess ideologier
- 2015
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Den svenska folkmusiken har alltsedan den ”upptäcktes” av akademiker under början av 1800-talet varit behäftad med ett tankegods som genom historien nyttjats för sina syften av såväl höger- som vänsterorienterade politiska rörelser. Då detta av många forskare i flertalet studier redan redovisats, är denna musikpedagogiska avhandlings främsta syfte att undersöka huruvida ideologier med rötter i tysk nyromantik och svensk nygöticism rönt inflytande på hur lärande och tradering över tid gestaltats.Studien, som är en sammanläggningsavhandling bestående av fyra artiklar och en historisk studie, har berört synen på lärande i den tidiga spelmansrörelsen under 1920-talet, folkmusikutbildning i nutid på Framnäs folkhögskola, samt lärande och tradering i ett spelmanslag. Metoderna som använts i de olika artiklarna har beroende på respektive undersöknings syfte varit av både kvantitativ och kvalitativ art. De teorier som använts har i huvudsak varit Bourdieus fältteori och Ricœurs Mimesisteori; Liedmanns begreppspar Manifesta och Latenta ideologier, samt Lave & Wengers teorier om situerat lärande och praxisgemenskap.I resultaten har det framkommit att spelmännen under 1920-talet i flera avseenden anammade ett under 1800-talet framarbetat tankegods som uppmuntrade ett autodidakt och gehörsbaserat lärande, samt en förändrad syn på repertoar som premierade äldre låttyper som polska och vallåt, framför nyare låtar som schottis och polka. Det framkommer även i studien att en betydande del av synen på folkmusikens tradering lever än idag såväl inom det institutionaliserade som icke-institutionella folkmusikfältet.
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| 1472. |
- Vrček, Aleks, 1991-
(författare)
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Tribology of Rolling-Sliding Contacts under Mixed Lubrication : With focus on a Crankshaft Roller Bearing Application
- 2020
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- A continuous increase in environmental legislation to reduce CO2 emissions is forcing engineers and scientists to develop more efficient and durable mechanical components, i.e. bearings, crankshafts, gears, etc. Such components are forced to operate under more severe operating conditions, reduced lubrication conditions, and under increased power density. The main failure mode has switched from traditionally subsurface to surface-initiated fatigue, typically caused by surface distress or micro-pitting. In this work, the tribology of rolling/sliding contacts, mimicking rolling bearing contact kinematics, operating under mixed lubrication conditions was studied. A special focus was directed to investigate the feasibility of employing such contacts in a crankshaft rolling bearing application by studying the tribological interface between a crankshaft and a roller. Three bearing steels were identified, selected, and then test specimens were manufactured from these steels for this work to represent a possible crankshaft rolling bearing steel for a four-cylinder light-duty internal combustion engine (ICE), as the current crankshaft steel does not meet the requirements to represent the rolling bearing component. Three tribological screening techniques were selected for this work to understand and investigate the surface performance, i.e. micro-pitting and wear damage of the rolling/sliding contact. The effect of the surface roughness and hardness, steel, and lubricant on the surface performance was investigated. This work was purely experimental, utilizing two tribological test devices: a twin-disc machine and a ball-on-disc machine. The results from this work will allow us to select and optimize the tribology of crankshaft rolling bearing contacts and bearing contacts in general to maximize the surface performance and in turn, contribute to increased efficiency and reliability of mechanical components. Based on the results from this Ph.D. work, micro-pitting and wear damage presents the main damage mode that can be associated with the engine tribology for a crankshaft rolling bearing. Micro-pitting and wear damage were found to be strongly dependent on the surface roughness and hardness combination of both contacting surfaces. A critical hardness difference was found between both surfaces, which is dependent on steel and heat treatments, where wear mode changes from severe fatigue wear to mild wear. A fully formulated state-of-the-art engine oil showed an increased wear component and, in some cases, eliminated micro-pitting damage compared to using only the base oil. Furthermore, it was shown that the ZDDP additive, present in the engine oil, can function as an anti-wear (AW) additive, as intended, or an extreme pressure (EP) additive depending on the contact iv severity. The latter increases the wear component through mild corrosion and delamination of the surface tribolayer, which leads to surface-initiated fatigue.
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| 1473. |
- Vuorinen, Esa
(författare)
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Structure and properties of advanced fine grained steels produced using novel thermal treatments
- 2012
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Fine grained advanced steels exhibit favourable mechanical properties for applications requiring high strength, ductility and impact toughness. These properties result from a microstructure containing a fine distribution of several phases including ferrite, austenite, martensite and bainite. The bainite phase is in the form of fine lamellas of ferrite and carbon-enriched austenite which due to proper control of the chemical composition is lacking the nanometre scaled carbides associated with traditional bainite. The mechanisms of bainite phase transformations in steels have been debated since the naming of bainite in 1934, and range from diffusion-controlled (reconstructive) to diffusionless (displacive). Interest in the manufacture and application of fine grained advanced multiphase steels can be dated back to the 1970s, and it has been intensified after the turn of the century with the industrial production and application of such steels. The structure and mechanical properties of fine grained advanced steels produced using novel thermal treatments are described. The results of in-situ x-ray diffraction studies of the austenite to bainite transformation process provide information about the effect of carbon redistribution on the formation of transformation products. Transformation microstructures created by various thermal treatments are characterised using optical and scanning electron microscopy, which reveal the presence of martensite, bainite (in various forms), ferrite and retained austenite. Microstructural control is found to be possible by quenching the steels from the austenite phase to temperatures below the start temperature of martensite formation (determined by steel composition). The quenching is followed by isothermal treatment for varying times at temperatures related to the formation of transformation products (bainite in particular). This combined heat treatment also increases the rate of phase transformation in comparison with isothermal treatments. Thus multiphase microstructures are produced, which are found to possess favourable mechanical properties, in particular tensile strength, toughness and wear resistance. In press hardening of 0.26wt-carbon steels, by using the combined heat treatment described, the yield strength was found to be comparable to existing materials and the ductility was found to be higher. Welding tests of medium carbon steel with control of the post weld time temperature cycle in accordance with the combined heat treatment process minimized the risk of brittle phase formation in the weld as well as the heat affected zone. In addition the wear resistance in sliding as well as in rolling-sliding was shown to be better for austempered medium carbon high-silicon steels with fine grained ferritic austenitic microstructure in comparison with conventional steels. The presented work can be regarded as a contribution to the current world-wide effort to develop the 3rd generation advanced high-strength steels, which are expected to be a substantial part of the structural steel market before the end of the present decade. The switch to such steels in a large number of applications in manufacturing of transport vehicles and other products, will be comparable with the switch from plain carbon steels to HSLA steels in the seventies and eighties.
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| 1474. |
- Waara, Patric
(författare)
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Lubricants influence on wear in sharp rail curves
- 2006
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Rail lubrication in curves was widely introduced in Sweden during the 1970’s due to the high wear rate of gauge faces in sharp curves. The first tests performed in Sweden showed that lubrication decreased wear rates by roughly 10 times. Based upon these results, the Swedish track system was equipped with wayside lubricators called Clicomatic. Aside from wear, rolling contact fatigue (RCF) is another limiting factor in railway infrastructure productivity. Head checking is one of the fatigue forms that arises in curves of heavily loaded tracks as well as fast train tracks. Head checkings grow at the rail head, close to the gauge corner. High pressure and a sliding motion lead to plastic strain of the material from the rail ball towards the gauge face. There is a coupling between wear rates and RCF damages, high wear rates may lead to reduced RCF damages and vice versa. Hence, frequent application of lubricants to the rail does extend the rail life by several times but may, on the other hand, lead to fatigue problems. Preventive grinding in combination with lubrication has been the most efficient way to avoid fast degrading of curved rail track. This thesis concerns the progress of rail lubrication in terms of how environmentally adapted lubricants function both in wayside lubricators and at the track. Another aspect of the thesis is to find a lubricant able to reduce the wear rate at the gauge face while simultaneously decreasing the crack growth at the rail head. One thought was to use controlled wear to reduce rolling contact fatigue. Controlled wear in this situation means that the usage of a lubricant should give a sufficiently high wear rate to continuously wear off the surface layers. Another idea along the same lines was that of low contact friction. Low friction in the contact gives less plastic strain and subsequently less head checking. Rapeseed oil had shown low contact friction in earlier testing, therefore, synthetic esters were of interest to examine in this application. From both field tests and laboratory tests it was concluded that the wear protection for environmentally adapted lubricants was comparable to that of previously used lubricants if they were applied by trackside lubricators. Although they were known to be more sensitive to low temperatures, testing showed how to overcome this issue. Wear and friction tests were performed in the laboratory to evaluate lubricating blends. The tests evaluated rolling / sliding as well as pure sliding contacts. The research performed in this thesis yielded the following results. Pure synthetic ester (TMP-Oleat and TMP-C8-C10) in a sliding contact resulted in high wear rates and a lot of abrasive marks at the surface. By adding friction modifiers, the friction as well as the wear rate decreased considerably in the sliding contact. In the rolling sliding contact, synthetic ester alone and synthetic ester with the addition of friction modifiers both showed similarly low friction and wear rates. PAO gave higher friction, but at the same time, the surfaces had significantly fewer cracks as compared to synthetic ester formulations. One observation was that surfaces lubricated by synthetic esters became less hard and the hardness interval was wider than those lubricated with PAO. One explanation is that even if the overall friction is low, local spots of high friction between asperities can lead to localized strain and crack initiation. The conclusions are that Rapeseed oil is the recommended base for rail lubricants. The tested synthetic esters are a more expensive alternative useful if excellent low temperature properties are needed. Graphite is not necessary in the lubricant if it is applied continuously by a wayside lubricator. Twin-disc tests showed that low contact friction does not necessary mean that crack initiations are avoided in the surface. In conclusion, the base fluid and the additives influenced not only the wear rate but also the ability for cracks to grow.
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| 1475. |
- Wahl, Joel
(författare)
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Multimodal applications in medical technology that utilize Raman spectroscopy
- 2022
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Biology can often be explained by structures and interactions between molecules. It is therefore of importance for medical sciences that the chemical reactions and molecular compositions of biological samples can be measured. The purpose of this thesis is twofold. Firstly, to develop methods for measuring the underlying mechanisms of the lung disorder pulmonary hypertension. Secondly, to investigating the possibility of classifying brain tissue for safer resection of brain tumors. A multimodal approach is often motivated, as there exist many different measurement techniques. In this thesis Raman spectroscopy has been applied both as the main measurement modality and in cooperation with other methods.Raman spectroscopy is a label free optical measurement technique that measure inelastic scattering from materials that are illuminated by a monochromatic light source. Raman scattering results in a weak signal that is uniquely proportional to the chemical structure of the sample. When measuring biological samples, Raman scattering is accompanied by a strong intrinsic fluorescent signature that can overshadow the signal. To elucidate the underlying Raman spectrum, it is generally preprocessed to allow further analysis. There are many methods available for preprocessing; a selection of commonly used methodologies has been included here, as well as methods of my own design. The most novel approach being a neural network that was trained on synthetic spectra to perform preprocessing without relying on user defined variables, which is common for other methods (Paper A). The neural network resulted in improved preprocessing when compared to a control predictor, with test data from paraffin, ethanol, and polyethylene, as well as spectra based on simulations.Hypoxic pulmonary hypertension (PH) is a condition where the arteries in the lung-walls are blocked due to prolonged oxygen deprivation or lung disease. People who suffer from PH, often experience shortness of breath and fatigue. If the condition persists the added strain upon the heart from the increased resistance in the arteries will result in right-heart failure. Hypoxic PH is the result of permanently constricted pulmonary arterial smooth muscle cells (PASMCs). PASMCs reside in the arterial walls and react locally to reduced oxygen content by constricting. This effect is called pulmonary vasoconstriction (HPV) and results in the regulation of deoxygenated blood to areas of the lung that have more oxygen available. Full understanding of the mechanisms of oxygen sensing in PASMCs has importance for the development of new treatments against PH. To this end a sealed microfluidic system was designed with the purpose to enable multimodal measurements of the response of cultivated PASMCs to acute hypoxia including Raman spectroscopy, patch clamp, and imaging (Paper B). The microfluidic system was initially tested using Raman spectroscopy and oxygen sensing to investigate the reaction of PASMCs to hypoxia. The results were compared to an open flow system that showed a higher variation of the desired oxygen content (21% or 4%) compared to the designed closed microfluidic system. The system was later reworked and tested with simultaneous measurements using Raman spectroscopy, oxygen sensing, imaging, and patch-clamp (Paper C). With this setup it was possible to track the molecular response in the mitochondria in correlation with the activity of the calcium-ion channels and the mechanical response of the PASMCs.The main modality used in clinics for brain tumor imaging is magnetic resonance imaging (MRI). Structural MRI gives neurosurgeons information regarding the size and mass effects of tumors. However, during surgery it can be difficult to assess the marginal zone of tumors. Improvements have been made by incorporating fluorescence guided resection (FGR) in the standard practice of many operating rooms in Europe. FGR relies on measuring the emission from metabolized precursor molecules. However, the drawback of FGR is that it is not tumor specific and has reduced sensitivity in low-grade tumors and children. In this thesis the option of incorporating a Raman probe setup, to fill in the gaps of other methods has been discussed. During this preliminary discussion it was noted that there is no standard approach for preprocessing and many different methodologies have been employed by various researcher. Therefore, measurement on fresh brain tumor tissue from a Raman microscopy setup was preprocessed using commonly applied methods, in addition to a pretrained neural network, to investigate the variations of the outcome (Paper D). It became apparent that different methods and variable choices can alter the distinctive spectral features. The conclusion being that it is important to be both transparent and specific when explaining how data has been prepared prior to analysis to enable reproducible results.
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| 1476. |
- Wahlberg, Rickard
(författare)
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Konst och marknad : en studie av resursanskaffningens inverkan på konstnärlig produktion
- 2001
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The aim of this thesis is to assess the influences of the procurement of resources within artistic production. The thesis consists of two studies. Study I has dealt with the programme planning for a Swedish theatre. Special focus was given to the concept of quality, in terms of artistic value and customer orientation, and an anticipated conflict between art and the market. The method used was case study approach utilizing observation, interviews, and document analysis. Addition to description of the programme planning process, the findings also indicate that, quality was not explicitly discussed in the selection of neither an individual play nor the programme as the whole. The point should also be indicated that, the findings of the study did not show any explicit conflict between artistic considerations and what the market expected. In study II the search for artistic considerations and the conflict between art and market were the main focus. Investigation of new cases, utilizing interviews and document analysis indicated that art producers were rather unaware of the market wants and the given considerations with respect to artistic quality were only fragmentary. However, the conflict between art and market were identified and possible ways to handle the conflicts were also identified.
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| 1477. |
- Wall, Peter
(författare)
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Homogenization of some partial differential operators and integral functionals
- 1998
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This thesis is devoted to some problems connected to the theory of homogenization of partial differential operators and integral functionals. The thesis consists of an introduction and three different parts, A-C. In the introduction we give an elementary presentation of the basic ideas in the homogenization theory. Moreover, the introduction also serves as an overview of the field and points out where the results contained in this thesis fit in. The first part, Part A, consists of one paper and a complementary appendix and it deals with the limit behavior of the solutions of a sequence of quasi-linear equations. Part B consists of three papers in which bounds on the homogenized integrand for non-linear problems are developed. Moreover, examples where the bounds are optimal are given. The third part, Part C, consists of four papers which consider some further mathematical and engineering aspects on the homogenization method. Several numerical results are also presented and compared with theoretical results.
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| 1478. |
- Wallin, Stefan
(författare)
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Rethinking network management solutions : models, data-mining and self-learning
- 2012
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Network service providers are struggling to reduce cost while at the same time improving customer satisfaction. This thesis addresses three relevant underlying challenges to achievieng these goals: - managing an overwhelming flow of low-quality alarms - understanding the structure and quality of the delivered services - automation of service configurationAll of the these add to an operator's operational costs since manual work is required in order to understand the alarm and service status as well as for configuring new services. We propose solutions based on domain-specific languages, data-mining and self-learning. We look at how domain-models can be used to capture explicit knowledge for alarms and services. In addition, we apply data-mining and self-learning techniques to understand the alarm semantics. The alarm solution is validated with a quantitative analysis based on real alarm documentation and an alarm database from a large mobile service provider. A qualitative analysis of the service management solutions is given based on prototypes and input from service providers.We present an approach to alarm interfaces by providing a formal alarm model together with a domain-specic language, BASS. This means that we can verify the consistency of an alarm interface and automatically generate artifacts such as alarm correlation rules or alarm documentation based directly on the model. From a baseline without any correlation, our alarm domain-model based on vendor documentation could automatically find the root-cause alarms in 40% of the cases. In the process of producing an alarm model from pre-existing alarm documentation for a commercial product, we found over 150 semantic warnings.We also propose a domain specific language called SALmon, which allows for efficient representation of service models, along with a computational engine for calculation of service status. Furthermore, this thesis illustrates how we can achieve automatic service configuration based on YANG, the domain-specific language standardized in the IETF. Prototypes show that the service domain-models can capture the semantics of service models, and automatically render parts of the service management solution. It is not always possible to capture expert knowledge in models. Therefore, we propose a data-mining and self-learning solution that learns alarm priorities from the decisions taken by the network administrators. The solution assigns the same severity as a human expert in 50% of the cases compared to 17% for the original alarm severity.
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| 1479. |
- Wallström, Lennart
(författare)
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Cell wall bulking and distribution of different chemicals in pine, Pinus Sylvestris
- 1998
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The interaction between wood, Pinus sylvestris, (60% RH) and polyethyleneglycol (PEG) of different molecular weights (PEG 200 and PEG 1500), pentaerythritol and glycerol, impregnated into the wood, has been investigated using Scanning Electron Microscopy, EDS-analysis, dynamical mechanical techniques (DMTA), X-ray diffraction (WAXS) and macroscopic dimensional measurement. Reduced dimensional changes after impregnation when exposed to environments with changing moisture content, showed that the stabilization effect of glycerol and PEG 200 impregnation is very good. The other chemicals used, especially pentaerythritol, were not as effective as glycerol and PEG 200. Cell wall measurements using SEM show that an increase in cell wall thickness gives a corresponding increase in stabilization effect. DMTA-measurements showed that interaction between wood molecules and the chemicals used differs. In general, a higher degree of cell wall penetration of the chemicals gives a better stabilization effect. WAXS- investigations showed free crystalline pentaerythritol, PEG 1500, glycerol and PEG 200. Examination using SEM/EDS-linescan of potassium stained chemicals confirmed the results from the cell wall thickness measurements. However, the better resolution obtained in the STEM/EDS-linescan showed an inhomogenous distribution of the chemical in the cell wall. High temperature dried and green wood of Swedish pine was impregnated with glycerate and silver nitrate. Silver was precipitated in the cell wall by a new method. A significant difference in the distribution, size and location of the silver was observed. The silver particles are small and dispersed in the green wood samples but clustered and irregulary spaced in the dried specimens. The inhomogenous distribution in the dried specimens is believed to be the result of damage inside the wood cell walls due to drying stresses, which in turn will negatively affect the dimensional stabilizing result. The strength and energy to fracture is increased by a factor of two if wood not is allowed to be dried before cell wall bulking. This is because the impregnating chemical (glycerol in the present case) in the cell wall substitutes some of the moisture and therefore limits drying stresses. The glycerol is believed to be soluble inbetween the hemicellulose. The average distance between the silver particles in the impregnated green wood indicates that the impregnant is distributed in the cell wall at the microfibrilar level. Experimental results showed that the fastest diffusion path into the cell wall is from the lumen over the pit membrane through the compound middle lamell and not from the lumen through the secondary wall layer S3. The darker compound middle lamella seen in TEM is believed to be an artefact, as it is possible that the ML is thicker than the other layers in the wood cell wall after microtoming.
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| 1480. |
- Wallström, Peter
(författare)
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On Value and Waste
- 2016
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Value and waste are concepts that are used in improvement projects. In lean the concepts are fairly simple. Reduce the waste and the value has increased. However, value is both multidimensional and differs over time. If the concepts value and waste are to be used, the concepts must be clearly defined and measured. Otherwise, value can be reduced for the customer/user and the cost increased for the producer/seller. The purpose in this thesis is to investigate how value and waste are perceived by different stakeholders, how value and waste are related, and how value and waste are measured. The focus of the study is the improvement of production and services. The study does not investigate the product/service development. The conclusions are based on a number of cases and research from different fields such as resource-based view and marketing. The study use mix of qualitative and quantitative methods. Measures of forecasting accuracy and their relations where explored with different statistical tools in order to understand the influence of measures and dimensions. The view of value concerning energy efficiency was examined in a statistical analysis of a survey concerning stakeholders’ view of a specific value, energy efficiency, as well as their influence on the value creation process. A multiple qualitative case study explores the relation between value and waste in different settings and the consequences of waste focus. The findings in the multiple case study are confirmed and elaborated further by an additional case study, both qualitative and quantitative, of value stream mapping.Value and waste are analysed with the use of order winners and qualifiers. Also, a model to clarify the consequences of mixing value creation and value exchange for customer/user and producer/seller have been defined and used in the analysis.Depending on the stakeholder there is a difference between whether value can be regarded as a use value, exchange value or both. Even if exchange value is related to a specific moment in time, use value is not. The view of value differs among stakeholders which increase the risk of sub-optimisation in production.Value and waste have multi-dimensional properties and there are links between the different dimensions. The relationships depend upon the situation in question. The lean seven types of waste are not independent dimensions. Also, the concept of waste as anti-value is too simplistic. In all cases studied the focus is on waste, not value. Also, it is often the symptoms of waste that are of interest in measures taken not the root causes. Reduction of waste without considering the value can create new waste. Since waste is a dependent variable, it should not be measured without considering value. Another complication is that value and waste often occurs at different points in time and in different settings.Single measures are sensitive to its environment. Several measures are more robust. Measures distort and influence the perception and thereby the decision of the studied phenomena. Also, the notion of value and waste becomes harder to define and trace as the resolution and detailing of the studied process increases.
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