| 1. |
- Nilsson, Kristina, 1986-
(författare)
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Oxidative dissolution of doped UO2 and H2O2 reactivity towards oxide surfaces : A kinetic and mechanistic study
- 2014
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Oxidative dissolution of std. UO2 and UO2 doped with Cr2O3 and Al2O3, i.e. ADOPT, induced by H2O2 and γ radiation has been the main focus in this licentiate thesis. The catalytic decomposition of H2O2 on oxides like Gd2O3, HfO2, CeO2, Fe2O3 and CuO were also investigated.A kinetic study was performed by determining first and second order rate constants together with Arrhenius parameters for the decomposition of H2O2. The reactivity of H2O2 towards the oxides mentioned was observed to differ significantly despite their similarities. In the mechanistic study, the yields and dynamics of the formation of the intermediate hydroxyl radical from the decomposition of H2O2 was determined for the oxides and found to differ considerably. A turnover point could be found for most of oxides studied, i.e. an increase in the rate of hydroxyl radical scavenging after a specific amount of consumed H2O2.The reactivity of the std. UO2 and ADOPT towards H2O2 was similar to what was observed for other UO2-based materials in previous studies. The oxidative dissolution in radiation experiments showed a slight but significant difference. This was attributed to a difference in exposed surface area instead of an effect of doping. The difference in oxidative dissolution yield was too small to be significant which supports the previous conclusion.Leaching experiments using spent nuclear fuel were also performed on the two types of fuel showing the same behavior as the unirradiated pellets, i.e., a slightly lower 238U release from ADOPT. The difference was attributed to difference in exposed surface area. The release of fission products with low UO2 solubility displayed a higher release from ADOPT which was attributed to a difference in matrix solubility. Cs was released to a larger extent from std. UO2. This is attributed to the larger grain size of ADOPT, extending the diffusion distance. The release of lanthanides and actinides was slightly higher for the conventional UO2, nevertheless the difference was relatively small.
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| 2. |
- Ghasemi, Yahya, 1982-
(författare)
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Aggregates in Concrete Mix Design
- 2017
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The importance of studying the behaviour and properties of concrete can be highlighted by considering the fact that concrete is the most used man-made material in the world. The very first step in making concrete is its mix design and deciding the type and amount of constitutes used in the production of concrete which should fulfil the requirements of the final product. Mix design models are commonly used for the purpose of proportioning concrete ingredients while anticipating the properties of the final product. The current document deals with the commonly used principals in mix design models namely particle packing theory and excess water/paste layer theories. The conducted studies includes an investigation on accuracy of particle packing models (Toufar, 4C, CPM) and also tries to address the issue with measurement of specific surface area of particles as an essential input to water/paste layer theories. It has been observed that the particle packing models can predict the packing density with acceptable margin. However, it should be mentioned that the particle packing models by themselves are not mix design models but should be rather used as a part of a mix design. In addition, it was found that the accuracy of calculating the specific surface area of particles based on their size distribution curve can be further improved by assuming angular platonic solids as uniform shape of aggregate instead of traditional approach of assuming spheres for aggregates’ shape.
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| 3. |
- Javadi, Mohammad Saleh, 1986-
(författare)
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Computer Vision Algorithms for Intelligent Transportation Systems Applications
- 2018
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- In recent years, Intelligent Transportation Systems (ITS) have emerged asan efficient way of enhancing traffic flow, safety and management. Thesegoals are realized by combining various technologies and analyzing the acquireddata from vehicles and roadways. Among all ITS technologies, computervision solutions have the advantages of high flexibility, easy maintenanceand high price-performance ratio that make them very popular fortransportation surveillance systems. However, computer vision solutionsare demanding and challenging due to computational complexity, reliability,efficiency and accuracy among other aspects. In this thesis, three transportation surveillance systems based on computervision are presented. These systems are able to interpret the imagedata and extract the information about the presence, speed and class ofvehicles, respectively. The image data in these proposed systems are acquiredusing Unmanned Aerial Vehicle (UAV) as a non-stationary sourceand roadside camera as a stationary source. The goal of these works is toenhance the general performance of accuracy and robustness of the systemswith variant illumination and traffic conditions. This is a compilation thesis in systems engineering consisting of threeparts. The red thread through each part is a transportation surveillancesystem. The first part presents a change detection system using aerial imagesof a cargo port. The extracted information shows how the space isutilized at various times aiming for further management and developmentof the port. The proposed solution can be used at different viewpoints andillumination levels e.g. at sunset. The method is able to transform the imagestaken from different viewpoints and match them together. Thereafter,it detects discrepancies between the images using a proposed adaptive localthreshold. In the second part, a video-based vehicle's speed estimationsystem is presented. The measured speeds are essential information for lawenforcement and they also provide an estimation of traffic flow at certainpoints on the road. The system employs several intrusion lines to extractthe movement pattern of each vehicle (non-equidistant sampling) as an inputfeature to the proposed analytical model. In addition, other parameters such as camera sampling rate and distances between intrusion lines are alsotaken into account to address the uncertainty in the measurements and toobtain the probability density function of the vehicle's speed. In the thirdpart, a vehicle classification system is provided to categorize vehicles into\private car", \light trailer", \lorry or bus" and \heavy trailer". This informationcan be used by authorities for surveillance and development ofthe roads. The proposed system consists of multiple fuzzy c-means clusterings using input features of length, width and speed of each vehicle. Thesystem has been constructed by using prior knowledge of traffic regulationsregarding each class of vehicle in order to enhance the classification performance.
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| 4. |
- Larsson, Mats, 1960-
(författare)
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De ”riktigt kristna”, deras ”wänner” och ”motståndare” : en lokal- och frikyrkohistorisk studie av Askers baptistförsamlings identitet och mentalitet, 1858−1887
- 2007
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The purpose of this work is to do a qualitative study of the identity of the Baptist congregation in Asker and the mentality which is created in that congregation during the period 1858–1887. The question at issue concerns the content, the creation, the continuity, the changes, the rate of exclusion, the expressions, etc of the identity and the mentality.The dissertation is divided into five parts: Part one (chapter 1–2) includes issues of theoretical and methodological interest. The purpose of part two (chapter 3–5) is to give some background information, to sketch the landscape in which the Baptist congregation of Asker is placed. Part three (chapter 6–13) is the main part of the dissertation, in which the results of the study of the eight selected areas are presented and analysed. Part four (chapter 14–15) is the part where the results of the studies of the different areas are put together and the whole picture of the identity and mentality of the congregation is presented. The conclusion is that the identity is constructed out of two kinds of relations, an inner religious and several outer relations, such as the Lutheran state church, the society, the history and so on. These relationships construct the identity. The congregation mediate their identity through preaching, through special institutions and through the normative common life of the congregation. The mentality of the congregation is characterized by spiritual rationality, dualistic thinking, insecure security, limited democracy, and assured faith and efficiency In the last fifth part we find some words for further study and thinking, two appendixes and the list of sources and literature.
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| 5. |
- Lundström, Mats Johan, 1973-
(författare)
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Planering och hållbar bebyggelseutveckling i ett energi- och klimatperspektiv
- 2010
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- ”Det kommunala planmonopolet” gör att kommunerna är viktiga aktörer i utmaningen att minska energianvändning och klimatpåverkan inom bebyggelse- och transportsektorerna, vilka står för en övervägande del av landets totala energianvändning. Den största potentialen i kommunernas planering och reglering av ny bebyggelse ligger i möjligheten att påverka bebyggelsens lokalisering och täthet, vilket har betydelse för resandets omfattning och val av transportsätt. Plan- och bygglagen (PBL) ger kommunerna vissa möjligheter att påverka energianvändningen och energitillförseln för ny bebyggelse, men de är tämligen begränsade. Variabler som mikroklimat och stadstyper med låg omslutningskvot påverkar bebyggelsens energianvändning i ett byggnadsfysiskt perspektiv, men ur ett administrativt perspektiv spelar detta ingen roll sedan energikraven i Boverkets byggregler sedan några år tillbaka ställer krav på hela byggnadens energiprestanda och inte på enskilda byggnadsdelar. Om byggreglernas krav istället skulle gälla byggnadens energianvändning i ett livscykelperspektiv skulle detta ge en mer rättvis bild samtidigt som planeringsfrågor som placering av bebyggelse och samt stadstyper skulle påverka energianvändningen. Vidare efterfrågas riktlinjer för hur användningen av elektricitet i bebyggelsesektorn ska miljöbedömas samt en statlig samsyn om elens roll ibland annat uppvärmnings- och transportsektorerna.Den stora effektiviseringspotentialen i bebyggelsesektorn finns dock i den befintliga bebyggelsen, vilket inte kan styras med vare sig markanvändningsreglering enligt PBL-planeringen eller Boverkets byggregler – det är fastighetsägarnas ansvar. Men planering kan omfatta så mycket mer än bara reglering. PBL:s organisation och krav på samrådsprocesser gör den kommunala planeringen till en viktig utvecklingsarena där såväl fastighetsägare som andra aktörer kan bjudas in att delta. Istället för ett traditionellt tvingande uppifrånperspektiv skulle den kommunala planeringen i högre grad kunna inta ett underifrånperspektiv och arbeta mer positivt och visa på möjligheterna att minska energianvändningen och få en mer hållbar energitillförsel, frågor som är bra både ur ett miljö- som ekonomiskt perspektiv. Planeringen skulle vidare behöva bli mer strategisk och genomförandeinriktad.I forsknings- och utvecklingsprogrammet Uthållig kommun fysisk planering har nya planeringsmetoder och -verktyg introducerats i fem kommuner, med syfte att integrera energi- och hållbarhetsaspekterna i den kommunala fysiska planeringen. En studie av den introducerade arbetsmetodiken visar att det går bra att kombinera rationella och kommunikativa planeringsmetoder och -verktyg. Det breda och inkluderande tillvägagångssättet har lett till att de deltagande har ökat sin kunskap om och sett större samband mellan planering, energi, bebyggelse och transporter, men även ökad förståelse för andra aktörers synsätt och kompetenser. Studien visar att såväl rationellt tänkande och expertkunskap som lokala, vardagliga erfarenheter och kunskaper är viktiga i planeringsprocessen. Det behövs kunskap om såväl processledning som sakkunskaper om exempelvis energi och miljöpåverkan.
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| 6. |
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| 7. |
- Nilsson, Josefin A., 1985-
(författare)
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Juvenile birch in Sweden : Selected stem characteristics for interior and furniture applications
- 2019
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- In response to the furniture industry’s growing demand for raw material, large volumes of juvenile silver birch and downy birch stems available from pre-commercial thinning operations in Sweden’s forests could offer solutions. However, such stems are not currently used on an industrial scale, and most research conducted on birch stems in general has neither focussed on young trees nor the potential use of the central stem part around the tree pith. The resulting lack of knowledge about the juvenile part of birch wood thus requires additional information about the material properties of birch, which could encourage its use for various purposes in the furniture and other industries.The initial literature review performed for this thesis has highlighted some properties of juvenile birch required for its use as a furniture material, as well as identified topics concerning the physical characteristics of juvenile birch about which knowledge is currently limited. Consequently, the objectives of this thesis were to explore some characteristics of juvenile birch—bark thickness, wood-to-bark bonding ratio after drying, variations in the density and width of growth rings, and anatomical growth response to fertilisation—in order to increase the knowledge.The material studied came from mixed birch and Norway spruce stands at two sites in southern Sweden, namely Asa and Toftaholm. The birch stems were naturally regenerated silver birch and downy birch, with breast height diameters between 30 and 83 mm. Fertilised and unfertilised silver birch trees were sampled at Toftaholm, whereas unfertilised stems of silver birch and downy birch were sampled at Asa. The characteristics of stems from the pith to bark (radial direction) and along the stem (longitudinal direction) were measured. The wood-to-bark bonding ratio on downy birch after drying was calculated as the percentage of the stem circumference with full contact between the wood and bark, while oven-dry density and basic wood density for silver birch were determined by using the water displacement method. The impact of ring width on wood density was statistically analysed, and an image analysis of the wood anatomy was conducted to elucidate their relationship.Amongst the results, bark thickness along the stem had the highest deviation in the section closest to the stump. Moreover, the wood-to-bark bonding ratio after drying measured for juvenile downy birch seemed to depend more on the stem’s diameter than the sampling height along the stem. Such results are relevant for processors seeking to estimate the volume of wood under the bark. The wood-to-bark bonding ratio was highest for diameters between 30 and 39 mm, and neither did that relationship correlate with the sampling height along the stem.Variation in wood density in the radial and longitudinal directions in juvenile silver birch suggested that such density negatively correlated with growth rate (ring width). That relationship held true for stems at each site and between the sites, irrespective of management or growing conditions. As expected, mean wood density was lower in fertilised trees than in unfertilised ones, and towards the bark, radial density increased more in trees that grew more slowly. At the same time, variation in longitudinal density in young silver birch trees was low. Quantitative wood anatomy studies confirmed that the fertilised juvenile birch had younger cambia, thinner cell walls, and fewer vessels per mm2 than unfertilised trees in the same diameter class.Overall, the knowledge generated in the study may facilitate the industrial use of juvenile birch stems and wood in interior and furniture applications. The role of wood anatomy in determining the mechanical performance of juvenile birch stems should be further examined, however, to possibly reveal new opportunities for the use of juvenile birch.
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| 8. |
- Nilsson, Katarina
(författare)
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MIND : Optimization method for industrial energy systems
- 1990
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The MIND optimization method is a tool for life cycle cost minimization of a flexible range of industrial energy systems. It can be used in analyses of energy systems in response to changes within the system, changes of the boundary conditions and synthesis of energy systems. In analysing industrial energy systems there are a variety of issues to consider in finding the best way of production. Both the energy supply part and the energy demand part is of great significance. The structure of the energy supply part is often decided on economic terms such as fixed costs, fuel prices or energy tariffs but also on availability. The energy demand is depending on the technology employed and the layout of the system. A change to new technology or recondition of old equipment may as well as alterations in the production schedule give considerable overall savings. In order to comprise all aspects in the analysis it is essential that the optimization method can handle: all occurring flows in the energy system, time-dependent components and conditions, non-linearities. A change regarding the production schedule, kind of energy or renewal of process equipment may cause a change of material and energy flows as well as a change of the interaction between them. Since industry as a rule has a production goal to fulfil it is necessary to represent both material and energy flows in the calculations. Time dependency for components indicates that process equipment must be represented in a way that allows different process routes to be chosen within the industrial system. Changes in boundary conditions, such as varying energy rates or climatic conditions, will also have to be represented. This implies that the system has to be represented with a proper time division. It is also necessary to let flows pass between time steps to be able to consider storage of both material and energy. Optimization of industrial energy systems at the component level involves non-linear relationships, such as energy demand functions and investment cost functions. It is important to use the proper level of accuracy in the representation of equipment units. If non-linear relationships are not included there may be considerable errors involved. The accuracy of representation must be chosen for each industrial system to be optimized. These demands can be met in optimization with mixed integer linear programming. Non-linear relationships can be approximated with step functions and piecewise linear segments giving the opportunity to optimize all levels of energy systems. The objective of the optimization is to minimize the life cycle cost of the studied energy system. The life cycle cost includes both fixed and variable costs. Two applications are presented to show the flexibility of the MIND method, heat treating processes in the engineering industry and milk processing in a dairy.
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| 10. |
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