| 1. |
- Johansson, Emma M.
(författare)
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Controlling the Pore Size and Morphology of Mesoporous Silica
- 2010
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Mesoporous silica with a hexagonally ordered pore structure (SBA-15) has been synthesized. Through variations in the synthesis conditions several morphologies, such as fibers, sheets and separate rods, have been realized. Furthermore, additions of heptane and NH4F make it possible to synthesize SBA-15 with pores as large as 18 nm in the sheet morphology. Mechanisms for the formation of different morphologies have been suggested. In the case of fibers and sheets, the amount of heptane present during the synthesis determines the final morphology. For low concentrations, the heptane enters the micelles and increases the pore size while the particles (crystallites) attaches to each other end to end. When the heptane concentration increases, the heptane droplets increase in size, and above a critical droplet size the crystallites attach with one short end towards the droplet, forming the sheet morphology. The crystallites can also be separated. This is the case of the rod morphology. The separation is performed by shortening the stirring time and increasing the HCl concentration. The increased amount of HCl increases the hydration rate of the silica precursor, which can be used to control the thickness and length of the rods. Furthermore, the reaction time has been decreased from 20 h for all morphologies to less than 4 hours. The materials have been characterized with nitrogen sorption, electron microscopy and x-ray diffraction. Also, thermogravimetric analysis and fourier transformed infrared spectroscopy have been used for studying the removal of surfactants.
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| 2. |
- Ehrström, Monica, 1970-
(författare)
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Uppmärksamhet för bedömning : att följa varje barns lärprocesser för en likvärdig utbildning i förskolan
- 2023
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The purpose of this study was to contribute with knowledge about the tension between preschool teachers' mission to teach and support children's learning on the one hand and the mission to assess children's learning processes on the other hand, in relation to equality in education. In Swedish preschools, children with different experiences meet, all of whom should have the opportunity to develop and learn based on their varied circumstances and needs. According to the Education Act (SFS, 2010:800), preschool education must be equal, and all children must have the opportunity to learn and develop as far as possible based on their potential. However, previous research (Alasuutari, Vallberg Roth & Markström, 2014) indicates that assessment involves risks for children’s identity creation. This study examines how seven preschool teachers tackle the challenge of assessing and paying attention to individual children in their ongoing learning processes. A sociocultural perspective (Vygotskij, 1978) has been used to study preschool teachers' reasoning about assessment in relation to each child's possibilities for being supported in their proximal development zone. The sociocultural perspective stresses the importance of cultural tools for communication. Stimulated-recall interviews were conducted with seven preschool teachers in Sweden. Content analysis was used to reveal the views that emerged in preschool teachers’ descriptions.In the preschool teachers' reasoning, different strategies for assessment and methods for making the child's learning processes visible as well as approaches for following the progression in children's learning processes have emerged, which can create both opportunities and limitations for children to learn based on their potential. Findings indicate three areas significant for assessment in relation to an equivalent education in this study. Firstly, there is clarity regarding the approach to assessment, what is to be given attention and assessed and how the assessment should be carried out. Secondly, the preschool teachers in the study have knowledge about various methods to make children's learning processes visible and thus possible to follow over time. Thirdly, the preschool teachers in the study know how to draw attention to and make visible the child's learning from a holistic perspective. The Licentiate thesis highlights different strategies for assessment, methods for making the child's learning processes visible and approaches for following the progression in children's learning processes that emerged during the preschool teachers' reasoning. The study has shown that attentiveness (Elbaz, 1992) can be used as a concept to bridge the tension surrounding assessment.
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| 3. |
- Johansson, Christoffer, 1985-
(författare)
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Simplified dynamic analysis of railway bridges under high-speed trains
- 2013
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The world-wide development of new high-speed rail lines has led to more stringent design requirements for railway bridges. This is mainly due to the fact that a train at high speeds can cause resonance in the bridge superstructure. In order to avoid problems of this kind, it has become essential to perform dynamic simulations, which are usually carried out in a time consuming finite element program. The main reason for not using an analytical solution is that this type of solution only exists for simple bridges, e.g., simply supported bridges.The aim of this thesis, is therefore the development of a simplified analytical model for preliminary dynamic analyses of railway bridges. The model is then used in several studies, both parametric and probabilistic ones, to determine the dynamic response of various railway bridges under moving loads. Special attention is paid to acceleration levels in the bridge superstructure, because previous studies have shown that these are often decisive. In the design, both the model and the numerical simulations can be used with considerable effectiveness to help engineers to define their structural systems.All bridges, throughout this thesis, have been modelled with elastically supported multi-span Bernoulli-Euler beams. The amount of dissipated energy is modelled using modal damping. The train load is modelled by concentrated loads, which implies that the vehicle-bridge interaction is not considered. A model with these characteristics can be used to analyse simply supported concrete bridges as well as multi-span steel bridges. Another advantage of the proposed method is that the solution is exact, because the equation of motion has been solved using a Laplace transform. A lot of effort has been made to have a model both as simple as possible and flexible enough to be able to study a wide variety of structures.The results of the case studies have shown that concrete bridges are more suitable than steel and composite bridges for use in the new high-speed lines. The simulations have also shown that short-span railway bridges have problems in meeting the design requirements. This confirms the high acceleration levels that were recorded in France, just after the inauguration of the new high-speed line between Lyon and Paris, on several short-span bridges. Furthermore, it was found that a multi-span bridge has a reduction in its dynamic response of up to 60 % compared to a similar simply supported bridge.
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| 4. |
- Johansson, Hans, 1956-
(författare)
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Towards a Holocene tephrochronology for the Azores
- 2015
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The Azores is situated in the North Atlantic Ocean and is one of the most active volcanicregions in the Northern Hemisphere. The volcanic history of the islands is fairly wellknown and several explosive trachytic eruptions have been reported but the geochemicalcompositions of the glass component of the tephra as well as the dispersal oftephras to distal areas are less well known. The purpose of this study is twofold: (1) topresent major element geochemistry of the glass component from several historic aswell as prehistoric tephras, including the trachybasaltic Capelinhos AD 1957‐58eruption on the island of Faial, and the trachytic explosive eruptions of Sete Cidades(c. AD 1440), Fogo A (c. 5000 BP), Fogo AD 1563 and Furnas AD 1630 on the island ofSão Miguel; (2) to present a refined tephrostratigraphy for the island of Pico. Analyses ofmajor element geochemistry suggest that tephras from the three active stratovolcanoeson São Miguel can be separated in biplots showing e.g. FeOtot vs.TiO2 and FeOtot vs. CaO.The tephrostratigraphy of Caveiro bog on the island of Pico is based on a radiocarbondated core with eight tephra layers extending back to c. 7000 BP. All tephras are oftrachybasaltic/basaltic trachyandesitic composition except the oldest layer, which is ofbasanitic composition. An attempt was made to correlate the tephra record of Caveirobog with the previously investigated Lake Caveiro. A tephra‐based correlation betweenthe Caveiro bog and Lake Caveiro is not straightforward and only three tephras inCaveiro bog can possibly be correlated with tephras found in the sediments of LakeCaveiro.Proximal glass data from the Furnas volcano on São Miguel suggest that distal cryptotephrasfound in Ireland may have an origin in the Azores and not on Jan Mayen aspreviously has been suggested. The similarity of the proximal tephras on São Miguel anddistal tephras in Ireland is demonstrated by high similarity coefficients (>0.95) andbiplots showing major element composition also support a correlation between Azoreaneruptions and distal tephras in Ireland. Thus, trachytic tephras erupted from explosiveeruptions on the island of São Miguel may have a potential to contribute to theconstruction of a European‐wide tephrochronology framework.Trachytic tephras erupted from explosive eruptions on the Azores may be more widelydispersed than previously thought and may provide useful isochrones for correlation ofpaleoclimate archives in the north‐central Atlantic, North Africa and the Iberian regions.The trachybasaltic/basaltic trachyandesitic tephras erupted from cinder cones on PicoIsland are probably only useful for a local tephrochronology in the Azores region, andnot for a wider Atlantic or European framework.
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| 5. |
- Johanzon, Conny
(författare)
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Hur bra är våra processer? : Värdering av den inre effektiviteten
- 2006
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This study investigates possibilities for measuring efficiency in service processes. Although there has been considerable research around service processes over the last 25 years, concepts of measurement and evaluation of service processes are rare.The aim of the study is to identify different factors that can affect service efficiency in order to provide a practical, useable model for evaluating the performance of certain service processes. To develop a framework for further research, two service processes are analyzed. These processes were "Student examination writing" at Örebro University and "Passenger Ground Service Delivery" (PGSD) at SAS Ground Services. These processes were used to discover background factors which then structured a search of relevant research literature.Four factors were found in the studied processes, namely lead-time, flexibility, capability and resource utilization. These factors, and relations among them, are used to construct an evaluation model.The model is validated by testing in seven groups with members who are familiar with the analysis of service processes. The conclusion from the tests is that the model can be used for evaluation of service processes.
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| 6. |
- Stockhult, Helén, 1968-
(författare)
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Medarbetaransvar – ett sätt att visa värderingar : Ett konceptualisering av medarbetarnas ansvar och ansvarstagande i callcenter
- 2005
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Stockhult, H. (2005) Medarbetaransvar – ett sätt att visa värderingar. Enkonceptualisering av medarbetarnas ansvar och ansvarstagande i callcenter.(Employee responsibility – a way of expressing values. A conceptual study ofresponsibility and how it is assumed in call center). Written in Swedish. ÖrebroStudies in Business 1. 219 pp.The focus of this study is on responsibility and how it is assumed in call centers.Call centers have developed during the last few decades and they are representinga new way of providing customer service. In scientific management there is asharp division between the planning and the execution of work. This division isalso very evident in most call centers today. But managers today often implicitlyexpect employees to take responsibility for more than the ascribed work task.The employees also expect a working situation where they are trusted with a lotof opportunities to take responsibility. In the light of these facts, the question thatshould be answered in this study is: In what ways are employees takingresponsibility in the call center organization?The knowledge acquired is based on theoretical assumptions aboutresponsibility. It is assumed that responsibility is partly given to the employee bymanagement, but also assumes responsibility on the basis of other criteria, thatcome from within the individual. The theories of responsibility are used forinterpreting actions in the call center organization. Empirically the study includestwo call center organizations. One of the call centers is mostly selling products orservices for other companies. The other call center is a nordic bank that givessupport to and sells products to the customers of its own.The results from the study confirm that besides the responsibility given bymanagement, the employees assume some other responsibilities that they perceiveas their own, self-imposed, responsibilities as employees. These self-imposedresponsibilities include responsibility for the customer, for the colleagues and foronesself. To assume these self-imposed responsibilities, the employees must tosome extent, act in reverse regarding the responsibilities given by the employer.Another conclusion is that the role of the group manager is important for the callcenter operators’ way of assuming responsibility. The last conclusion is thatalthough employers often state that they want the employee to take personalresponsibility, this favourable attitude does not show in the call center practice.
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| 7. |
- Terelius, Håkan, 1987-
(författare)
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Consensus Algorithms in Dynamical Network Systems
- 2013
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Dynamical network systems are complex interconnected systems describing many real world problems. The current trend is to connect more and more systems together, and at the same time requiring continuous availability. To this end, it is crucial to understand the dynamic behaviors of networked systems.This thesis makes three contributions in this area.First, we study the important problem of gathering data that are distributed among the nodes in a network. Two specific tasks are considered: to estimate the size of the network, and to aggregate the distribution of local measurements generated by the nodes. We consider a framework where the nodes require anonymity, and restricted computational resources. We propose probabilistic algorithms with low resource requirements, that quickly generate arbitrarily accurate estimates. For dynamical networks, we improve the accuracy through a regularization term which captures the trade-off between the gathered data and a-priori assumptions on the dynamics.In the second part of this thesis, we consider a dynamical network system where one node is misbehaving due to a failure. We specifically seek robustness conditions that guarantee that the entire network system is still functional. The nodes' dynamics is governed by consensus updates, and we present thresholds on the interaction strengths that determines if the system will reach consensus, or if the system will diverge.Finally, a P2P network is utilized to improve a live-streaming media application. In particular, we study how an overlay network, constructed from simple preference functions, can be used to build efficient topologies that reduce both network latency and interruptions. We present necessary and sufficient convergence conditions, as well as convergence speed estimates, and demonstrate the improvements for a real P2P video streaming application.
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