| 71. |
- Edeskär, Tommy
(författare)
-
Use of tyre shreds in civil engineering applications : technical and environmental properties
- 2006
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- End-of-life tyres are a disposal problem regarding the large volumes produced every year. Tyre shreds are primarily produced to reduce the transportation volumes of end-of-life tyres after collection. Within the European Union, there is a ban for landfilling tyre material in order to reduce the total landfilling volumes and to encourage recycling measures. Until recently the main disposal option has been energy recovery in industrial processes. However, legislation acts has recently been taken in the European Union to encourage recycling and recovery of end-of-life-tyres and re-use of tyre materials in construction works is listed as one disposal option.Tyre shreds possess interesting technical properties that could be beneficially used in civil engineering applications. Some characteristic properties of tyre shred materials are the low density, high elasticity, low stiffness, high drainage capacity and high thermal insulation capacity. These properties open up possibilities for utilisation of the material in an innovative manner.The overall aim of this thesis work has been to describe and evaluate tyre shreds as a civil engineering construction material from environmental and technical point of view. The thesis work has included laboratory tests and full scale field tests to investigate technical and environmental properties of tyre shreds and to investigate the tyre shred material behaviour in a real road construction. Furthermore, the state-of-the-art knowledge in the area has also been analysed and presented.In the laboratory studies technical properties focused on compaction and compression behaviour of tyre shreds have been investigated. In a field study of a built road, tyre shreds has been tested and evaluated, during four years, as lightweight fill and frost insulation material. Environmental properties of tyre shreds, mainly leaching characteristics, have been studied in laboratory tests and monitored in two full scale field tests.Based on the results in the laboratory studies a model is proposed for evaluation of stressstrain properties and prediction of compression behaviour. Recommendations for construction works and pavement design are suggested based on the road construction field study results.Conclusions regarding the studied leaching properties of tyre shreds, based on the laboratory tests and the field monitoring, are that zinc and iron are the metals mainly released and that the release of the studied organic compounds, i.e. PAH and phenols, are low. From an environmental point-of-view focus should be moved from PAH-compounds towards other compounds that are more interesting from mobility perspective and lack of knowledge. It is concluded from this thesis work that PAH is not a pollution problem in the area of use of tyre material covered by this work.Applications where tyre shreds have been successfully utilised as construction material, are e.g. as draining layers in landfills and as material in trotting tracks and paddocks. The utilisation of the material in trotting tracks and paddocks is especially interesting since the unique elasticity of the material is utilised. The potential of utilising tyre shreds in civil engineering construction is big. Since the available amounts of material is limited there is a possibility to direct the use of tyre shreds to the most favourable applications of tyre shreds and still solve the disposal problem of end-of-life tyres.
|
|
| 72. |
- Edfelt, Åsa
(författare)
-
The Tjårrojåkka apatite-iron and Cu (-Au) deposits, northern Sweden : products of one ore forming event
- 2007
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The Tjårrojåkka area is located about 50 km WSW of Kiruna, northern Sweden, and hosts one of the best examples of spatially related apatite-iron (Kiruna type) and Cu (-Au) deposits in Sweden. The results from this project show that the two deposits are genetically related and indicate the presence of a younger, previously unknown, 1780 Ma generation of apatite- iron ores in northern Sweden. The bedrock in the Tjårrojåkka area is dominated by intermediate and basic extrusive and intrusive rocks. The 1880 Ma intermediate volcanic rocks, belonging to the Porphyrite Group, formed in association with subduction- related magmatism in a volcanic arc environment close to the Archaean continental margin. The overlying basalts and related feeder dykes formed through extrusion of mantle derived magma during a local extensional event in a subaquatic back arc setting. The area was metamorphosed at epidote- amphibolite facies and deformed during at least three stages, creating NE- SW, E-W, and NNW-SSE striking structures. The Tjårrojåkka deposits can be considered as belonging to the Fe-oxide-Cu- Au (IOCG) group of deposits representing two "end-members" of the class. Several generations and overlapping hydrothermal alteration stages indicate a long, complex history of fluid activity between 1780 and 1700 Ma related to the formation and post ore modification of the deposits. The strongly altered host rock shows enrichment of alkalis related to mineralisation due to the formation of albite, scapolite, and K-feldspar. It is not obvious whether the massive part of the apatite-iron ore formed from an iron rich melt or through hydrothermal replacement, but a hydrothermal system was active at least at a late stage during the deposition of the iron ore, producing the apatite-magnetite-actinolite breccia, the copper mineralisation, as well as the extensive hydrothermal alterations. The ore forming fluids were CO2-bearing, moderately to highly saline CaCl2- NaCl-rich fluids of most likely magmatic origin. The magnetite ore deposited at around 500 to 650°C followed by the copper mineralisation between 150 and 450°C. Cooling along with decrease in salinity were important factors for metal precipitation at Tjårrojåkka. A NE trending shear zone acted as a major fluid channel and a structurally favourable location for the deposition of the copper (-gold) mineralisation. From apatite chemistry, it is evident that there is a fundamental difference between typical Kiruna type apatite-iron ores and copper mineralised apatite-iron deposits of IOCG character and could potentially be used as a tool for distinguishing copper mineralising apatite-iron systems from barren.
|
|
| 73. |
- Ek, Kristina
(författare)
-
The economics of renewable energy support
- 2005
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This dissertation consists of an introductory part and five self-contained papers, all related to the issue of promoting renewable power sources. Paper I provides an econometric analysis of the most important determinants of Swedish households’ willingness to pay a premium for “green” electricity. Methodologically we draw heavily on recent developments in the literature on integrating norm motivated behavior into neoclassical consumer theory. The analysis is based on postal survey responses from 655 Swedish households, which are analyzed within a binary choice framework. The results indicate that the impact of choosing “green” on the household budget largely influences the willingness to contribute to “green” electricity schemes, as do the degree of perceived personal responsibility for the issue and the felt ability to affect the outcome in a positive way. We find only limited support for the idea that perception about others’ behavior affect individual moral norms and behavior; stronger support is instead found for the presence of a prescriptive social norm. In paper II we perform an empirical test the overall hypothesis that the framing of renewable power support in a “conditional” and an “unconditional” scenario, respectively, will tend to trigger different types of moral deliberations. We approach this research task by analyzing the responses to dichotomous willingness to pay questions from two different versions of a postal survey sent out to 1200 Swedish house owners. The responses are analyzed within a random effects binary probit model and the estimated marginal effects support the notion that different types of factors tend to dominate choices depending on the support scheme considered. Paper III analyzes the attitudes towards wind power among residential electricity consumers, as well as the foundations of these attitudes. The results are based on a postal survey that was sent out to 1000 Swedish house owners, and these results suggest that the average Swedish house owner is in general positive towards wind power. The probability of finding an average individual in support of wind power decreases with age and income while people who act on environmental values are more likely to be positive. In addition, people that are more inclined to express public preferences are also more likely to be positive towards wind electricity than people who are less inclined to do so. Paper IV scrutinizes the Swedish households’ preferences over the environmental characteristics associated with wind power by applying a choice experiment approach. The results are based on a postal survey that was sent out to 1000 Swedish house owners. The non-monetary attributes included in the choice scenario were: the noise level, location, height, and the grouping of windmills. According to the results the location of wind turbines has the most pronounced impact on the utility of the average individual. If the environmental external costs are to be minimized the results suggest that new schemes should primarily be located offshore, and large wind farms located onshore should be avoided. Finally, paper V provides an econometric analysis of innovation and diffusion in the European wind power sector. The empirical results indicate that reductions in investment costs are an important determinant of increased diffusion of wind power, and these cost reductions are in turn explained by learning-by- doing activities but less so by knowledge accumulating as a result of public R&D support. Feed-in tariffs also play a role in the innovation and diffusion processes. The higher is the feed-in price the higher is, ceteris paribus, the rate of diffusion. High feed-in tariffs, though, also tends to have a negative effect on average cost reductions as they induce wind generators to choose high-cost sites and provide fewer incentives for cost cuts.
|
|
| 74. |
- Ekevad, Mats
(författare)
-
Modelling of dynamic and quasistatic events with special focus on wood-drying distortions
- 2006
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This thesis deals mainly with computer simulations of wood-drying distortions, especially twist. The reason for this is that such distortions often appear in dried timber, and the results are quality downgrades and thus value losses in the wood value chain. A computer simulation is a way to theoretically simulate what happens in reality when moisture content in timber changes. If the computer simulation model is appropriate and capable of realistic simulations of real events, then it is possible to study what happens with the timber distortions if some parameters in the simulation model are changed. In that way, a good simulation model is a good tool to use when trying to reduce wood-drying distortions by altering some parameters in the process of producing timber. Computer simulations have the comparative advantage over real-world experiments of being cheaper and faster to perform, but the disadvantage that the outcome may be doubtful if the simulation model is bad. Wood is an anisotropic material that is often modelled as an orthotropic material, i.e., a material that has three orthogonal directions at each point with different material properties. A method to measure the orthotropic directions in wood nondestructively was the subject of paper 1. The method was to calculate the directions from the information in a series of two-dimensional computed tomography (CT) images. Fictitious, small calculation spheres were distributed in the wood material, and the principal directions of inertia of these spheres were calculated using the density information in the CT images. The principal directions were assumed to be the radial, the tangential and the fibre direction at the point in question. Tests of the method on three wood samples showed that the method works, but that there was considerable spread in the results from individual spheres. The spread was reduced by calculating mean values for a number of spheres in the vicinity of each other. Twist of timber depends on various influencing variables. Traditionally, a formula from the late 50s by Stevens and Johnston, valid for single growth ring cylinders, has often been used to explain which variables influence twist. One interesting influencing variable in this formula is the spiral grain angle; the others are the moisture content change, the coefficient of moisture expansion and the radius of the growth ring cylinder in question. However, real boards are not single growth ring cylinders, and paper 2 deals with the dependence of twist of realistic boards on various influencing variables. Derivations were made on a theoretical and analytical level of the twist of timber, and the result was a formula whose first term corresponds to Stevens and Johnston's original formula; but the formula has also a second term. This second term is proportional to the gradient of the spiral grain angle and is especially important for timber sawn far from pith. The validity of the second term was shown by comparisons with finite element method (FEM) results and also with experimental results. The first step in simulating wood-drying distortions is to simulate the wood-drying process. The output of this moisture transport simulation is the moisture content of the wood piece as a function of time. We then use this output as input to a second step in which we simulate the shrinkage and deformation of the wood piece. A diffusion model was used here to simulate moisture transport, and this simulation requires diffusion and mass transfer coefficients. Such values from drying Norway spruce (Picea abies) sapwood were measured and reported in paper 3. Measurements of the moisture content during drying of a sample were made with CT, and the diffusion coefficient was evaluated with two methods. The first method used a one-dimensional and the second a two-dimensional diffusion model. No assumptions of the dependence of the diffusion coefficient on any functions or variables were made beforehand. Both methods showed about the same result and dependence on moisture content, but also on depth (distance from surface) of the diffusion coefficient. The depth dependence was only apparent near the surface. Comparisons of the evaluated values of the diffusion coefficient in general terms with other results were made and showed agreement. Industrial process changes aimed at reducing twist distortions are interesting to study. In paper 4, simulations of drying distortions were conducted, and pretwist during drying as a remedy to overcome twist of boards was tried. Paper 4 also contained results from laboratory experiments on the influence of the spiral grain angle and the degree of restraint and pretwist during drying on twist of boards. Results from an industrial test of the influence of the spiral grain angle and the degree of restraint on twist of boards were also described. The laboratory experiments and the industrial test were simulated with an FEM simulation model in two stages. First, the FEM model was calibrated by adjusting the yield stresses of the wood material in order for the results from the laboratory experiments to agree with the simulation model results. Then in a second stage, the simulation model was used to simulate the industrial test. The results showed that the FEM simulation model was capable of producing realistic results, but that there were some discrepancies between the industrial test results and the simulation results. The discrepancies were assumed to be due to biased measurements, insufficient knowledge of the distribution of the spiral grain angle or other causes.
|
|
| 75. |
- Elfgren, Erik
(författare)
-
Cosmic dust and heavy neutrinos
- 2007
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This Doctoral thesis treats two subjects. The first subject is the impact of early dust on the cosmic microwave background (CMB). The dust that is studied comes from the first generation of stars, which were hot and short-lived, ending their lives as giant supernovae. In the supernova explosions, heavy elements, produced through the fusion in the stars, were ejected into the interstellar medium. These heavy elements condensed to form dust, which can absorb and thus perturb the CMB radiation. The dust contribution to this radiation is calculated and found negligible. However, since the dust is produced within structures (like galaxy clusters), it will have a spatial correlation that could be used to detect it. This correlation is calculated with relevant assumptions. The planned Planck satellite could eventually detect and thus confirm this correlation. The second subject is heavy neutrinos and their impact on the diffuse gamma ray background. Neutrinos heavier than M_Z /2 ~ 45 GeV are not excluded by particle physics data. Stable neutrinos heavier than this might contribute to the cosmic gamma ray background through annihilation in distant galaxies as well as to the dark matter content of the universe. The evolution of the heavy neutrino density in the universe is calculated as a function of its mass, M_N, and then the subsequent gamma ray spectrum from annihilation of distant N-Nbar (from 0 < z < 5). The evolution of the heavy neutrino density in the universe is calculated numerically. In order to obtain the enhancement due to structure formation in the universe, the distribution of N is approximated to be proportional to that of dark matter in the GalICS model. The calculated gamma ray spectrum is compared to the measured EGRET data. A conservative exclusion region for the heavy neutrino mass is 100 to 200 GeV, both from EGRET data and our re-evalutation of the Kamiokande data. The heavy neutrino contribution to dark matter is found to be at most 15%. Finally, heavy neutrinos are considered within the context of a preon model for composite leptons and quarks, where such particles are natural. The consequences of these are discussed, with emphasis on existing data from the particle accelerator LEP at CERN. A numerical method for optimizing variable cuts in particle physics is also included in the thesis.
|
|
| 76. |
- Eliasson, Jens
(författare)
-
Low-power design methodologies for embedded internet systems
- 2008
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Embedded systems are resource-constrained special-purpose computers, capable of both sensing and controlling the environment they are placed in. An embedded system usually consists of both hardware and software. The hardware can be composed of sensors, actuators, processors, memory storage devices, communication peripherals, and power supplies. The software typically includes an operating system, device drivers, and an application-specific algorithm for controlling the system's behavior. A special class of embedded systems is comprised by systems that can communicate using standard Internet protocols. Such systems, called Embedded Internet Systems (EIS), are capable of transmitting sensor data directly to the Internet without using specialized gateways. Sensor nodes (nodes in a sensor network) are an example of specialized embedded systems. Sensor nodes with wireless communication capabilities can form a wireless network of sensors. Two types of such networks are usually distinguished - Wireless Sensor Networks (WSN) and Personal Area Networks (PAN). Wireless sensor networks may consist of hundreds or even thousands of sensor nodes; they can be used in industrial applications and deployed in hazardous environments, such as battlefields, volcanos, and forest fires. Personal area networks, on the other hand, are normally composed of a relatively small number of devices, which minimizes requirement on scalability. PAN devices use general-purpose technologies and standard protocols, such as Wi-Fi and Bluetooth, and they are designed for applications such as video and audio streaming, web browsing, and file transfer. Today's research on WSN technology is focused on creating power-efficient large-scale networks using highly specialized protocols and technologies; they are usually intended for scientific, military, and industrial usage scenarios. Research on PAN technology targets consumer needs, where two important requirements are interoperability, through the use of general-purpose technologies and protocols, and usability, often achieved by supporting dynamic address allocation and well-known service discovery protocols. When sensor nodes are used in personal area networks, they should have both features normally characteristic of WSN nodes and those more typical of PAN nodes. A sensor network based on general-purpose technologies should be power-efficient while at the same time enabling interoperability with consumer devices. By using consumer devices, such as mobile phones, and widely available access networks, such as GPRS and UMTS cellular networks, such sensor nodes can achieve worldwide mobility. This is in contrast to traditional wireless sensor networks where the focus is on achieving efficient communication within the network using highly specialized protocols and technologies. This thesis investigates the feasibility of using Embedded Internet Systems as wirelessly networked sensor nodes using standard protocols and commercial off-the-shelf (COTS) components. The focus is on reducing sensor nodes' power consumption while still allowing interoperability with standard consumer devices, such as mobile phones, PDAs, and computers. In other words, the goal is to merge WSN and PAN technologies to produce a new type of wirelessly networked sensor nodes with an operational lifetime in the range of months to years, which communicate using well-known protocols, such as Bluetooth and TCP/IP. Bluetooth was chosen since it is by far the most wide-spread protocol supported by existing consumer devices, and we call the resulting sensor networks Bluetooth Sensor Networks (BSN). BSN nodes are EIS devices used in the context of sensor networks, and the main motivation for this type of sensor networks is to allow sensors, such as GPS, pulse oximeters, and thermometers, to be used in conjunction with standard consumer devices and applications. The work presented in this thesis has resulted in a system architecture which supports sensor networks consisting of EIS devices with a lifetime of several years, energy scavenging capabilities, and user-oriented low-power operation. The use of TCP/IP and Bluetooth enables interoperability with existing infrastructures, such as the Internet, and mobility, when Bluetooth-enabled mobile phones are used as gateways to cellular networks. It has also be demonstrated that it is feasible to utilize Bluetooth and TCP/IP on resource-constrained networked sensor nodes, while still enabling system operational lifetimes in the range of months to years and using a total system volume of less than 10 cm3 .
|
|
| 77. |
|
|
| 78. |
- Engström, Jonas
(författare)
-
Some developments of the homogenization theory and related questions
- 2005
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This thesis is mainly devoted to homogenization theory and it consists of an introduction, five papers and two conference proceedings. The introduction gives an elementary presentation of the basic ideas in homogenization theory, serves as an overview of the field and points out where the results of this thesis fit in. A short description of the Rothe method is also included in the introduction. The first paper deals with reiterated homogenization of degenerate nonlinear monotone operators. In the second paper bounds and some numerical results for the homogenized degenerated p- Poisson equation are given. The third and fourth paper are devoted to stochastic homogenization where the third deals with random degenerated nonlinear monotone operators and the fourth with an approximation model, namely periodic approximaton, for elasticity properties of random media. In the fifth paper the Rothe method is generalized to the case with parabolic equations on non-cylindrical domains. In the last two papers some numerical aspects of the homogenization theory are investigated.
|
|
| 79. |
- Engström, Åsa
(författare)
-
A wish to be near : experiences of close relatives within intensive care from the perspective of close relatives, formerly critically ill people and critical care nurses
- 2008
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The overall aim of this doctoral thesis was to describe the experiences of close relatives within intensive care, from the perspective of close relatives, formerly critically ill people and critical care nurses. Data were collected by means of qualitative research interviews with close relatives of people who had been critically ill and cared for in an intensive care unit (ICU) and with the people themselves. Data were also collected by means of focus-group discussions with critical care nurses. Collected data were analysed using qualitative thematic content analysis and phenomenological hermeneutic interpretation. This thesis reveals that it was a frightening experience for close relatives to see the person critically ill in an unknown environment. It was important to be able to be near the ill person. Showing respect for and confirming the dignity of the ill person were essential. The uncertainty concerning the outcome for the ill person was hard to manage. Close relatives wanted to feel hope, even though the prognosis was poor. The presence of close relatives was taken for granted by critical care nurses. Information from close relatives made it possible for critical care nurses to provide personal care for the critically ill person. Critical care nurses supported close relatives by giving them information and being near. Close relatives were described as an important but demanding part of the critical care nurses' work. People who had been critically ill had felt their close relatives' presence. Through the help of close relatives they felt they were understood and safe. Close relatives made it possible for them to do various things, which were appreciated, but they also engendered feelings of guilt. They realized their own, and the close relatives' significance, which gave them the power to continue the struggle. The possibility for people who had been critically ill, and their close relatives, to return together to the ICU for a follow-up visit after discharge and talk about what happened during and after their stay in the ICU was appreciated. Receiving explanations and being able to discuss one's experience were valuable. Meeting the ICU staff again enabled them to express their gratitude for their work, to give opinions about the care and to suggest improvements. This thesis shows that the critically ill person is the focus of close relatives' existence. The uncertainty of the time causes close relatives' suffering and they felt vulnerable. To be able to be close to the critically ill person, to be allowed to participate in and receive explanations about what was happening and why, to be met by dignity and to be able to keep hope alive are all prerequisites for enduring a radically changed everyday life which close relatives experience when someone they love is, or has been, critically ill. The crucial challenge is how these needs can be met by the staff of the ICU.
|
|
| 80. |
- Enman, Josefine
(författare)
-
Fungal production and solid state chemistry of eritadenine : an integrated approach to development of an active pharmaceutical ingredient
- 2009
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The present thesis demonstrates an integrated approach to the development of a potential active pharmaceutical ingredient, eritadenine, a cholesterol reducing compound originating from the shiitake mushroom (Lentinus edodes). The main areas covered in the thesis are a method for quantification of eritadenine, production of eritadenine by submerged cultivation of fungal mycelia and investigation of the influence of process parameters on mycelial growth and production, and finally solid state characterizations of eritadenine. The usage of the fungus as a source of eritadenine requires an analytical tool for quantification of the compound. An HPLC method was hence developed for identification and quantification of eritadenine, using chemically synthesized eritadenine as a reference. The amount of eritadenine in fruit bodies of selected strains of shiitake was determined and with the method developed in this study, eritadenine concentrations up to ten times higher than previously reported were detected. Since both fruit bodies and mycelia of shiitake have been shown to contain eritadenine submerged cultivation of shiitake mycelia was investigated as an alternative source for this compound. The mycelia were cultivated in various submerged conditions, both in shake flasks and in bioreactors. It was found that both the mycelia and the culture media contained eritadenine, of which the major part was detected in the culture media. While the biomass concentrations were higher in shake flasks, the eritadenine concentrations were considerably higher in the bioreactors, which were assigned to morphological variations. In an attempt to improve the mycelial growth and eritadenine production, a growth promotive substance in the form of a water extract of DDGS, a by-product from drygrind ethanol facilities, was added to the culture media. It was demonstrated that an amendment of the cultivation media with this extract caused a considerable growth promotive effect on shiitake mycelia in bioreactor cultivations, along with enhanced eritadenine production. If eritadenine will be used as a pharmaceutical agent, understanding about the solid state chemistry of the compound is required. Raman spectroscopy is a valuable technique for investigation of structural properties; hence, a Raman reference spectrum with line assignments for the solid state of synthetic eritadenine was established. To further investigate the solid state chemistry of eritadenine, its synthetic analogue was slowly crystallized from water and different ethanol concentrations, at different temperatures. Solids formed from slow cooling of either water or aqueous ethanol showed crystallinity. No polymorphism was detected, irrespective of solvent system or temperature. However, dissimilar thermal behaviours were observed, deducing crystals derived from water as dihydrates and crystals derived from aqueous ethanol as 2.5 hydrates.
|
|
