| 1. |
- Abdikalikova, Zamira
(författare)
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Some new results concerning boundedness and compactness for embeddings between spaces with multiweighted derivatives
- 2009
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This Doctoral Thesis consists of five chapters, which deal with a new Sobolev type function space called the space with multiweighted derivatives. This space is a generalization of the usual one dimensional Sobolev space. As basis for this space serves some differential operators containing weight functions.Chapter 1 is an introduction, where, in particular, the importance to study function spaces with weights is discussed and motivated. In Chapter 2 we prove some new estimates for each function in a Tchebychev system. In order to be able to study compactness of the embeddings from Chapter 3 such estimates are crucial.In Chapter 3 we rewrite and present some results of L. D. Kudryavtsev, where he investigated one dimensional Sobolev spaces. Moreover, in this chapter we rewrite and discuss some analogous results by B. L. Baidel'dinov for generalized Sobolev spaces. These results are not available in the Western literatures in this way and they are crucial for the proofs of the main results in Chapter 4. In Chapter 4 we prove some embedding theorems for these new generalized Sobolev spaces. The main results of Kudryavtsev and Baidel'dinov about characterization of the behavior of functions at a singularity take place in weak degeneration of the spaces. However, with the help of our new embedding theorems we can extend theseresults to the case of strong degeneration.The main aim of Chapter 5 is to establish boundedness and compactness of the embedding considered in Chapter 4.In Chapter 4 basically only sufficient conditions for boundedness of this embedding were obtained. In Chapter 5 we obtain necessary and sufficient conditions for boundedness and compactness of this embedding and the main results are proved in a different way.
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| 2. |
- Alakangas, Lena
(författare)
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Sulphide oxidation, oxygen diffusion and metal mobility in sulphide-bearing mine tailings in Northern Sweden
- 2006
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Large quantities of sulphide-bearing mining wastes produced from ore processing are deposited throughout the world. Sulphide oxidation in the wastes may release acidic water with high concentrations of metals to the environment. Remediation strategies are usually site specific, since the physical and chemical properties of the wastes vary. Therefore, sulphide oxidation, oxygen diffusion and metal mobility in unoxidised and oxidised, remediated and unremediated wastes have been studied in the present work. The efficiency of different cover systems on unoxidised tailings from Kristineberg, were studied in pilot-scale test cells (5*5*3 m3)under field conditions. Clayey till, sewage sludge, apatite and Trisoplast were used as sealing layers and unspecified till as a protective cover. In one cell tailings were left uncovered. Unoxidised tailings in the test-cells in the initial stage after deposition showed relatively low sulphur release (600- 800 mg/l)in leachate waters, which probably was an effect of high moisture content in the tailings prior to deposition. Near-neutral pH found in the leachates was an effect of neutralisation by carbonate minerals present and lime (Ca(OH)2) added prior to deposition. Similar sulphur concentrations were found also in the uncovered tailings. The sulphide oxidation rate increased with time in the uncovered tailings, and decreased in the covered. The lowest oxygen concentrations were observed below the cover system with sewage sludge, which was the most effective barriar against oxygen in a short-term perspective. The oxygen fluxes through the clayey till and apatite layers were within the same magnitude and varied between 0.5 and 4 mole/year,m2. The Trisoplast layer seemed to have failed as a barrier against oxygen. Tailings studied at field scale at Laver and Kristineberg had oxidised for more than 50 years. The tailings at Kristineberg have high pyrite content (c.25% and 50%) and those at Laver have low grade of pyrrhotite (2-3%). The Laver tailings are unremediated, while at Kristineberg the tailings were remediated in 1996. The transport of metals in the drainage water at Laver decreased during a study period of 8 years. The transport of dissolved sulphur indicated a declining trend of sulphide oxidation rate in the tailings, which was confirmed by oxygen measurements in the tailings and weathering rate estimations. The decline was considered to be natural as a result of the increased distance that oxygen has to travel to reach unoxidised sulphide grains. The major part of the amounts of metals released by sulphide oxidation were secondarily retained in the tailings, and to a small extent in layers cemented by jarosite and Fe-(oxy)hydroxides. Sequential extraction of these layers showed that metals such as Cu and Pb were mostly associated with crystalline Fe-(oxy)hydroxides. Most important retention mechanism was, however, sorption onto minerals surfaces below the oxidation front. The studied Impoundment 1 at Kristineberg was remediated by two different methods; on one part a dry cover consisting of a sealing layer and a protective cover were applied, and the groundwater table was raised and a single dry cover applied on the other part. When the groundwater table was raised in oxidised tailings, secondarily retained metals such as Fe, Mg, Mn, S and Zn were remobilised resulting in increased concentrations in the groundwater. The concentrations declined with time, due to dilution by inflowing uncontaminated water. Decreased concentrations of Fe, Mg, Mn, S and Zn were observed also in the groundwater below the dry cover as the amount of percolating water decreased. The concentrations of trace elements such as Cd, Co, Cr, Cu, Ni and Pb were almost depleted in the groundwater, since these metals were retained within the tailings by mechanisms such as co-precipitation, precipitation and sorption. Analysis of pyrite grains by LA-ICP-SMS showed that pyrite surfaces were important for retention of As and Cu, in particular, but also for Cd and Zn. This study shows that the physico-chemical conditions expressed by pH and redox potential have a large impact on element mobility’s. For example, As was mobilised as a result of remediation, while the concentrations of most metals decreased in the drainage waters.
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| 3. |
- Albing, Malin
(författare)
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Contributions to process capability indices and plots
- 2008
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This thesis presents contributions within the field of process capability analysis. Process capability analysis deals with how to assess the capability of processes. Based on process capability analysis one can determine how the process performs relative to its product requirements or specifications. An important part within process capability analysis is the use of process capability indices. This thesis focuses on process capability indices and process capability plots. The thesis consists of six papers and a summary. The summary gives a background to the research area, a short overview of the six papers, and some suggestions for future research. The thesis summary also consists of some new results, not presented in any of the appended papers. In paper I, the frequency and use of process capability analysis, together with statistical process control and design of experiments, within Swedish companies hiring alumni students are investigated. We also investigate what motivates organisations to implement or not implement these statistical methods, and what is needed to increase the use. In papers II-III we generalize the ideas with process capability plots and propose two graphical methods, for deeming a process capable at a given significance level, when the studied quality characteristic is assumed to be normally distributed. In paper II we derive estimated process capability plots for the case when the specification interval is one-sided. In paper III we derive elliptical safety region plots for the process capability index Cpk and its one-sided correspondences. The proposed graphical methods are helpful to determine if it is the variability, the deviation from target, or both that need to be reduced to improve the capability. In papers IV-VI we propose a new class of process capability indices designed for the situation with an upper specification limit, a target value zero, and where the studied quality characteristic has a skewed, zero- bound distribution with a long tail towards large values. The proposed class of indices is simple and possesses properties desirable for process capability indices. The results in papers IV-VI are also valid for the situation with a target value, not equal to zero but equal to a natural lower limit of the quality characteristic. Three estimators of the proposed class of indices are studied and the asymptotic distributions of these estimators are derived. We also consider decision procedures, based on the estimated indices, suitable for deeming the process capability at a given significance level. The new results in the summary combines the ideas from paper II with the results in papers IV-VI and a graphical method for the class of indices proposed in IV-VI are derived.
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| 4. |
- Bark, Glenn
(författare)
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On the origin of the Fäboliden orogenic gold deposit, northern Sweden
- 2008
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- A new promising ore province, the Gold Line, southwest of the well- known Skellefte District, northern Sweden, is currently under exploration. This province hosts, so far, one operating mine, the Svartliden Au mine, and the recently closed Blaiken Zn-Pb-Au-Ag mine. The largest known gold deposit, the hypozonal Fäboliden orogenic gold deposit, in the area was recently granted mining permits. The deposit holds c. 54 Mt at 1.2 g/t Au, with a planned production of 4.6 Mt of ore/year. The mineralization at Fäboliden is commonly hosted in arsenopyrite-bearing quartz-veins, within a roughly N-S striking, steeply dipping shear zone in amphibolite facies volcano- sedimentary host rocks. The narrow belt of supracrustal rocks is surrounded by late- to post-orogenic Revsund granite. The gold is fine-grained (2-40 µm) and closely associated with arsenopyrite- löllingite and stibnite. Gold is found in fractures and as inclusions in the arsenopyrite-löllingite. Gold is also seen as free grains in the silicate matrix of the host rock. The hydrothermal mineral assemblage in the proximal alteration zone is diopside, calcic amphibole, biotite, and minor andalusite and tourmaline. This type of assemblage is commonly recognized in hypozonal orogenic gold deposits worldwide. The lateral extent of the proximal alteration zone is estimated to 30-50 meters, and there is a good agreement between diopside- amphibole-biotite alteration, quartz veining, and gold mineralization. The mineral assemblage in the distal alteration zone is characterised by the presence of Ca- and Fe-Mg amphiboles, hedenbergite, biotite, and quartz. The transition from the distal alteration into the regional metamorphic assemblage is diffuse, and the only discernable feature appears to be a gradual decrease of amphibole away from the mineralization. The ductile gold-hosting fabric progresses laterally across the Revsund granite contact and then disappears after a few meters inside the granite, suggesting that at least the final stages of mineralization syn- to postdate the emplacement of the c. 1.81-1.77 Ga Revsund granite. Relationships between garnet-biotite and graphite geothermometry, together with these field relationships, indicate that the late stages of mineralization at Fäboliden post-date regional peak-metamorphism in the area, which is estimated at c. 1.80 Ga. The Fäboliden gold mineralization is hosted by a reverse, mainly dip-slip, high-angle shear zone with a relatively small horizontal shear movement. The mineralization constitutes two sets of mineralized quartz veins, one steep fault-fill vein system that is parallel to the regional foliation and one flat-lying extensional vein system. Both vein sets are suggested to have been generated from the same stress field, during E-W shortening at c. 1.80 Ga. At least two types of ore shoot are present at Fäboliden, intersections between the fault-fill vein set and the extensional vein set and bends in the shear zone system both show elevated gold content, similar to many gold- quartz vein deposits globally. The fluids involved in the precipitation of gold at Fäboliden shows characteristics similar to other hypozonal orogenic gold deposits, such as a CO2-CH4-H2S fluid composition and pressure-temperature conditions of c. 4 kbar and 520-560°C. Sulphur isotope data ranges between -1.5 and +3.6‰. Oxygen and hydrogen isotope data ranges between +10.6 and 13.1‰, and -120 to -67‰, respectively. The hydrothermal fluids at Fäboliden are interpreted to have originate from a crustally contaminated magmatic source. The potential for future orogenic gold discovery in the Fennoscandian Shield is considered good. From this PhD study it is suggested that interesting targets, concerning exploration for orogenic gold in at least the Gold Line, would be areas associated with roughly N-S striking tectonic zones that were active at around 1.80 Ga.
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| 5. |
- Beeri, Guy
(författare)
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Some mathematical, numerical and engineering aspects of composite structures and perforated solids
- 2009
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- In this doctoral thesis in engineering mathematics we present some new modeling, numerical and engineering aspects and results concerning composite structures and perforated solids.The thesis consists of five papers, which are divided into three parts. Part A functions as an introduction where we look into some of the mathematical, numerical and engineering aspects of the effective in-plane elastic properties of periodic structures. We focus on one- and two-component composites and, in particular, we discuss locally anisotropic perforated structures. Moreover, we describe how the elastic properties of such and more general structures can be calculated. Finally, we present bounds and relations between different effective moduli.In Part B we study twelve of the simplest structures belonging to the class of one-component structures with holes and which, in addition, are three-fold rotational symmetric. We look into the effective elastic in-plane properties such as effective bulk and shear moduli and the so-called Vigdergauz constants. A comparative overview of all of these properties is given. Furthermore, we derive low-density asymptotics and present numerical data from finite element calculations. We also show that several of the studied structures have optimal elastic properties in the limit when the volume fraction of the connected material goes to zero. Finally, some remarks on the manufacturability of the structures are made.In Part C, which is divided into three papers, we continue to explore the effective properties of periodic structures. In paper [C1] we introduce a new model for estimating the elastic effective properties of regular hexagonal honeycombs. In contrast to previous cases, with this model we introduce a new formula, which match and complement the results obtained by Vigdergauz in 1999 in an essential way. Furthermore, by comparing some of the results with numerical finite element computations we find an improved formulae which enable us to estimate the effective properties with an accuracy better than one percent. In paper [C2] we study the effective elastic properties of regular triangular honeycombs. In particular, we obtain some simple approximate formulae for the corresponding Vigdergauz constants with accuracy better than one percent for all densities. In paper [C3] we study a scale of two-component composite structures of equal proportions with infinitely many microlevels. The structures are obtained recursively and we find that their effective conductivities are power means of the local conductivities.
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| 6. |
- Bengtsson, Fredrik
(författare)
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Algorithms for aggregate information extraction from sequences
- 2007
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- In this thesis, we propose efficient algorithms for aggregate information extraction from sequences and multidimensional arrays. The algorithms proposed are applicable in several important areas, including large databases and DNA sequence segmentation. We first study the problem of efficiently computing, for a given range, the range-sum in a multidimensional array as well as computing the k maximum values, called the top-k values. We design two efficient data structures for these problems. For the range-sum problem, our structure supports fast update while preserving low complexity of range-sum query. The proposed top-k structure provides fast query computation in linear time proportional to the sum of the sizes of a two-dimensional query region. We also study the k maximum sum subsequences problem and develop several efficient algorithms. In this problem, the k subsegments of consecutive elements with largest sum are to be found. The segments can potentially overlap, which allows for a large number of possible candidate segments. Moreover, we design an optimal algorithm for ranking the k maximum sum subsequences. Our solution does not require the value of k to be known a priori. Furthermore, an optimal linear-time algorithm is developed for the maximum cover problem of finding k subsequences of consecutive elements of maximum total element sum.
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| 7. |
- Brännström, Robert
(författare)
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Mobility management in heterogeneous access networks
- 2007
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This thesis proposes, describes and validates solutions to enhance mobility in heterogeneous access networks. Wireless access networks have become available almost everywhere and current research strives to make them pervasive. Users having wireless access to the Internet are driving the demand for mobile and heterogeneous solutions where services could be accessed from anywhere, any time and from any device. Future wireless connectivity will be provided through a mix of coexisting heterogeneous access network technologies. To enhance mobility in heterogeneous networks this thesis focuses on mobility management systems and connectivity of wireless multi-hop ad hoc networks to the Internet. In a wireless environment with overlapping service areas, mobile nodes need to select which gateway(s) to use to access the wireless infrastructure. The metrics used to select the point of attachment within an access technology are insufficient to compare the capacity of different technologies or multi-hop routes. This thesis proposes, describes and validates solutions to calculating network layer metrics and using them in gateway selection and handover decisions. To enable connectivity of a mobile ad hoc network (MANET) to the Internet, a gateway must bridge the wired single-hop and wireless multi-hop approaches. A MANET enables connectivity to more than one gateway at a time and combined with multihoming it provides seamless handover between subnets. The gateway selection and handover decisions are complicated by the multihoming capabilities. Connectivity to Internet services makes it important to maintain the efficient route to the gateway. It is also important to identify the location of a destination to separate the management of Internet and intra MANET destinations. This thesis proposes,describes and validates solutions to deploying multihomed mobility into MANETs and thereby handling multi-hop gateway discovery, registration of multiple gateways and tunneling to selected gateway(s). The solution maintains gateway connectivity in MANETs by installing routes to gateways using advertisements and manages route discovery based on the destination locality. Both applications with mobility awareness (e.g. SIP phones) and those without it must be supported by a mobility management system. The existence of network layer mobility management can enhance an application layer system. This thesis proposes, describes and validates deployment of a mobility management system with support of both application and network layer mobility. With wireless access networks some technologies might not support some types of applications and a single technology might not cope with all the application demands from a mobile node. Thus the control of individual traffic flows could be used to share the load on multiple access technologies and to direct flows over specified technologies. This thesis proposes, describes and validates solutions to identification and mobility management of individual traffic flows in a heterogeneous network environment. Finally this thesis proposes, describes and validates a deployment proposal of route evaluation and flow control to enable load balancing in wireless multi-hop networks.
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| 8. |
- Carlsson, Ella
(författare)
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Mars : plasma environment and surface hydrology
- 2008
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This doctoral thesis treats parts of the solar wind interaction with the Martian atmosphere and the water-related features known as gullies. The composition of the escaping plasma at Mars has been investigated in an analysis of data from the IMA sensor, which is a part of the ASPERA-3 instrument suit onboard the European satellite Mars Express. The goal of the investigation is to determine if there are any high abundances of escaping ion species incorporating carbon, such as in CO_2^+ . The most abundant ion species was found to be O^+ and O_2^+, followed by CO_2^+. The following ratios were identifed: CO_2^+/O^+ = 0:2 and O_2^+ /O^+ = 0:9. The escaping plasma, in form of ion beam events, has also been correlated to the magnetic anomalies found on the surface, where no clear association was found. Similar ion beams have also been detected on Venus, which does not have any crustal magnetic fields, and hence the fields are not required for the formation process of the beams. The ion beams' dependence of the direction of the solar wind convection electric field has also been studied, where a correlation was found, suggesting that the ion beams are accelerated by this field. The studies mentioned above are important in order to understand the evolution of Mars and its atmosphere, as well as plasma acceleration processes at non-magnetized planetary bodies. On 5 December 2006 the ASPERA instruments of both Venus Express and Mars Express detected a large enhancement in their respective background count level. These readings are associated with events of SEPs (Solar Energetic Particles), which are believed to be coupled with the CMEs (Coronal Mass Ejection) identified 43 ¡ 67 hours after the SEPs. The CMEs occurred on the far side of the sun (with respect to the locations of Venus and Mars), which indicates that these events can a®ect the space weather in areas situated 90 degrees in both azimuthal directions in the heliosphere with respect to the target. During this event the heavy ion outflow from the atmosphere of Mars increased by one order of magnitude, suggesting that EUV flux levels significantly affect the atmospheric loss from unmagnetized bodies. The gully formations have been investigated with data from the MOC, MOLA and TES instruments onboard the satellite Mars Global Surveyor. The features suggest that there has been fluvial erosion on the surface of Mars. The shallow and deep aquifer models remain the most plausible formation theories. Gully formation processes are important to understand since their eroding agent may be liquid water.
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| 9. |
- Drugge, Mikael
(författare)
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Interaction aspects of wearable computing for human communication
- 2006
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This thesis presents the use of wearable computers for aiding human communication over a distance, focusing on interaction aspects that need to be resolved in order to realize this goal. As wearable computers by definition are highly mobile, always on, and always accessible, the ability to communicate becomes independent of place, time and situation. This also imposes new requirements on the user interface of the wearable computer, calling for natural and unobtrusive interaction with the user.One of the key challenges in wearable computing today is to streamline the user’s interaction, so that it is tailored for the situation at hand. A user interface that takes too much effort to use, interrupts or requires more than a minimum of attention, will inevitably hamper the user’s ability to perform tasks in real life. At the same time, human communication involves both effort, interruptions and paying attention, so the key is to find a balance where wearable computers can aid human communication without being intrusive. To design user interfaces supporting this, we need to know what roles different aspects of interaction have in the field of wearable computing. In this thesis, the use of wearable computing for aiding human communication is explored around three aspects of interaction.The first aspect deals with how information can be conveyed by the wearable computer user, allowing a user to retrieve advice and guidance from experts, and remote persons to share experiences over a distance. The thesis presents findings of using wearable computing for sharing knowledge and experience, both for informal exchange among work colleagues, as well as enabling more efficient communication among health-care personnel. The second aspect is based on findings from these trials and concerns how the wearable computer interacts with the user. As the user performs tasks in the real world, it is important to determine how different methods of notifying the user affects her attention and performance, in order to design interfaces that are efficient yet pleasant to use. The thesis presents user studies examining the impact of different methods of interruption, and provides guidelines for how to make notifications less intrusive. The third and final aspect considers how the user’s physical interaction with the wearable computer can be improved. The thesis presents rapid prototyping of systems employing user centric design. Furthermore, a framework for ubiquitousmultimedia communication is presented, enabling wearable computers to be dynamically configurable and utilize resources in the environment to supplement the user’s equipment.All in all, the thesis presents how wearable communications systems can be developed and deployed, how their human-computer interaction should be designed for unobtrusive operation, and how they can come to practical use in real world situations.
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| 10. |
- Edfelt, Åsa
(författare)
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The Tjårrojåkka apatite-iron and Cu (-Au) deposits, northern Sweden : products of one ore forming event
- 2007
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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.
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