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  • 1.
    Jaque, Cassandra
    et al.
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    Johansson, Anders
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    Kromatografi av polära läkemedel och metaboliter med HILIC-teknik2013Independent thesis Basic level (degree of Bachelor), 10,5 credits / 16 HE creditsStudent thesis
    Abstract [en]

    The purpose of this project was to investigate if retention of polar compounds that are given to treat tuberculosis, diabetes, inflammatory bowel disease and childhood leukemia could be obtained with HILIC separation. By varying different parameters for different types of columns the compounds were analyzed with the aim of finding guidelines for future method optimizations. To perform these analyzes three different columns were tested – ZIC-HILIC (silica-based with zwitterions), ZIC-pHILIC (polymer-based with zwitterions) and XBridge Amide (amide functions). The results were evaluated with selected quality measures. The parameters being varied were pH, temperature, flow rate, type of buffer and ionic strength. In addition, comparisons between isocratic and gradient separations were performed.

     

    Over 1 000 analyzes were conducted in which retention of 16 of total 18 substances were successfully obtained with HILIC. The columns that generated the best results in terms of greatest number of identified compounds were ZIC-HILIC and XBridge Amide. ZIC-pHILIC offered a wide pH range but generally gave inferior chromatography. The influence of the different parameters on the results has not been investigated in sufficient scope. This means that no specific methods for the different drug groups can be reported.

  • 2.
    Subedi, Yuba Raj
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    The response of ecosystems to an increasingly variable climate2012Independent thesis Advanced level (degree of Master (One Year)), 40 credits / 60 HE creditsStudent thesis
    Abstract [en]

    A wide range of ecological communities ranging from polar terrestrial to tropical marine environments are affectedby global climate change. Over the last century, atmospheric temperature has increased by an average of 0. 60 C andis expected to rise by 1.1- 6.40C over the next 100 years. This rising temperature has increased the intensity andfrequency of weather extremes due to which a large number of species are facing risk of extinction. Studies haveshown that species existing on lower latitude are more sensitive to temperature variability compared to speciesexisting on higher latitude but temperature is increasing rapidly in higher latitude compare to lower latitude. Thisuneven distribution of temperature sensitive species and warming rate has highlighted the need for combined studiesof temperature variability and sensitiveness of species to predict how the ecosystems will respond to increasinglyvariable climate. Using a generalized Rosenzweig-MacArthur model, I explored how temperature variability andsensitivity of species will affect the extinction risks of species and how the connectance and species-richness ofecological communities will govern this response. This study showed that the risk of extinction of species mostlydepends on their sensitivity to temperature deviation from the optimum value and level of temperature variability.Among these two, sensitivity of species to temperature deviation was most prominent factor affecting extinction risk.In this study, connectance did not show any effect on mean extinction risk and time taken by a certain proportion ofspecies to reach pre-defined extinction thresholds. But, species-richness showed some effect on mean extinction riskof species. It was found that risk of extinction of species in species-rich communities was higher compared tospecies-poor communities. Species-rich communities also took shorter time before they lost 1/6 of the species. Thepresent study also suggests a possible tipping point due to increasing temperature variability in near future. In furtherstudies, different sensitivity of species at different trophic levels and the possible evolution of sensitivity of speciesshould also be consider while predicting how ecological communities will respond to changing climate in the longrun.

  • 3.
    Sahlberg, Jörgen
    Swedish Meteorological and Hydrological Institute.
    Physical modelling of the Akkajaure reservoir2003In: Hydrology and Earth System Sciences, ISSN 1027-5606, E-ISSN 1607-7938, Vol. 7, no 3, 268-282 p.Article in journal (Refereed)
    Abstract [en]

    This paper describes the seasonal temperature development in the Akkajaure reservoir, one of the largest Swedish reservoirs. It lies in the headwaters of the river Luleiilven in northern Sweden; it is 60 km long and 5 km wide with a maximum depth of 92 m. The maximum allowed variation in surface water level is 30 m. The temperature field in the reservoir is important for many biochemical processes. A one-dimensional lake model of the Akkajaure reservoir is developed from a lake model by Sahlberg (1983 and 1988). The dynamic eddy viscosity is calculated by a two equation turbulence model, a k-ε model and the hypolimnic eddy diffusivity formulation which is a function of the stability frequency (Hond o et al., 1993). A comparison between calculated and measured temperature profiles showed a maximum discrepancy of 0.5-1.0oC over the period 1999-2002. Except for a few days in summer, the water temperature is vertically homogeneous. Over that period of years, a weak stratification of temperature occurred on only one to two weeks a year on different dates in July and August. This will have biological consequences.

  • 4.
    Vastesson, Alexander
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, The Institute of Technology.
    Micro-Structuring of New Materials Combined with Electronic Polymers for Interfaces with Cells2012Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Materials based on novel Off-Stoichiometry Thiol-Ene polymers, abbreviated OSTE, show promising properties as materials forlow cost and scalable manufacturing of micro- and nanosystems such as lab-on-chip devices. The OSTE materials have tunablemechanical properties, offer possibility for low temperature bonding to many surfaces via tunable surface chemistry, and can beused in soft lithography. Unlike the commonly used elastomer poly(dimethylsiloxane), PDMS, the OSTE materials have lowpermeability for gasses, are resistant to common solvents and can be more permanently surface modified.In this master’s thesis project, the OSTE materials have been evaluated with focus on compatibility with cells, possibility fornanostructuring using soft lithography and the use of OSTE as a flexible support for conducting polymers.Results from cell seeding studies with HEP G2 cells suggest that cells can proliferate on a low thiol off-stoichiometry OSTEmaterial for at least five days. The biocompatibility for this type of OSTE material may be similar to poly(styrene). However, highlevels of free thiol monomers in the material decrease cell viability considerably.By using soft lithography techniques it is possible to fabricate OSTE nanochannels with at least the dimensions of 400 nm x 15nm. Combined with the advantages of using the OSTE materials, such as low temperature bonding and possibility for stablesurface modifications, a candidate construction material for future development of systems for DNA analysis is at hand.OSTE can serve as a flexible support for an adsorbed film of a conducting polymer with the possibility for future applicationssuch as electronic interfaces in microsystems. In this project, a film of PEDOT:PSS with the electrical resistance of ~5 kΩ wascreated by adsorption to an flexible OSTE material. Furthermore, results suggest that it is possible to further optimize theconductivity and water resistance of PEDOT:PSS films on OSTE.

  • 5.
    Carlander, Jakob
    Linköping University, Department of Management and Engineering, Energy Systems.
    Att bygga bostäder enligt miljöbyggnadskrav: En fallstudie i området Nya Wahlbecks2015Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Energy and resource efficiency is an important part in moving towards a sustainable society. In the year 2013, the total energy use in Sweden was 563 TWh and approximately 26 % of the energy was used in the residential and service sector. Within the residential and service sector, nearly 60 % of the used energy is for heating (Energimyndigheten, 2015). The construction of energy efficient buildings is a central part in creating a sustainable society and Nya Wahlbecks is supposed to become a city district which will show that it is possible to increase growth, quality of life and well-being and at the same time decrease the use of non recyclable and non reusable resources.The primary purpose of this master thesis has been to generate suggestions on how to design the residential buildings in the new city district Nya Wahlbecks, which will be built in east Valla in Linköping, so they can be certified in accordance to the environmental certification system Miljöbyggnad. Besides the primary purpose an investigation on how much electricity that can be generated with photovoltaic and how much energy that can be saved by the use of solar heating panels, has also been conducted. Finally a comparison in emissions of CO2-eqvivalents between a building that just meets the criteria´s of Boverkets Byggregler (BBR) and the generated building models was done.The results which the case study has generated, clearly shows that it is possible to build the new residential buildings in Nya Wahlbecks so that they will meet the different criteria’s for grade Silver and Guld from Miljöbyggnad. The requirements from Miljöbyggnad aim to have as low energy use as possible at the same time as a good indoor climate is kept. These two factors can be contradictions to one another, as for instance low energy use can be reached by having thicker insulation, but thicker insulation often results in higher indoor temperature which can then lead to deterioration in indoor climate. The investigations of energy use and indoor climate were conducted through simulations in the building-simulation program IDA-ICE, where several optimizations were done for different parameters to finally meet the requirements from Miljöbyggnad. Simulations with solar panels for heating and generation of electricity were also conducted with IDA-ICE. The results of the study shows that nearly 60 % of the used electricity in the project building can be generated from photovoltaic panels placed on the roof of the building. About 9 % of the buildings heating energy can be produced with solar panels placed in the same way as the photovoltaic ones. When it comes to emissions of CO2-eqvivalents there would be a difference in approximately 19 tons, which is equivalent to about 30 %, if the building meets the requirements of Miljöbyggnad Silver instead of just meeting BBR´s requirements.

  • 6.
    Antunez de Mayolo, Eduardo
    Linköping University, Department of Physics, Chemistry and Biology, Applied Optics .
    Study of the Optical Properties of sp2-Hybridized Boron Nitride2014Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Nitride-based semiconductor materials make it possible to fabricate optoelectronic devices that operate in the whole electromagnetic range, since the band gaps of these compounds can be modified by doping. Among these materials, the sp2-hybridized boron nitride has properties that make it a potential candidate for integration in devices operating in the short-wavelength limit, under harsh environment conditions, due to the strength of the B-N bond.  Nevertheless, this binary compound has been the less studied material among the nitrides, due to the lack of complete control on the growth process.

    This thesis is focused on the study of the optical properties of sp2-hybridized boron nitride grown by hot-wall chemical vapor deposition (CVD) method, at the Department of Physics, Chemistry and Biology, at Linköping University, Sweden. The samples received for this study were grown on c-plane aluminum nitride as the buffer layer, which in turn was grown by nitridation on c- plane oriented sapphire, as the substrate material. The first objective of the research presented in this thesis was the development of a suitable ellipsometry model in a spectral region ranging from the infrared to the ultraviolet zones of the electromagnetic spectrum, with the aim of obtaining in the process optical properties such as the index of refraction, the energy of the fundamental electronic interband transition, the frequencies for the optical vibrational modes of the crystal lattice, as well as their broadenings, and the numerical values of the dielectric constants; and on the other hand, structural parameters such as the layers thicknesses, and examine the possibility of the presence of roughness or porosity on the boron nitride layer, which may affect the optical properties, by incorporating their effects into the model. The determination of these parameters, and their relation with the growth process, is important for the future adequate design of heterostructure-based devices that incorporate this material. In particular, emphasis has been put on the modeling of the polar lattice resonance contributions, with the TO- LO model, by using infrared spectroscopic ellipsometry as the characterization technique to study the phonon behavior, in the aforementioned spectral region, of the boron nitride. On the other hand, spectroscopic ellipsometry in the visible-ultraviolet spectral range was used to study the behavior of the material, by combining a Cauchy model, including an Urbach tail for the absorption edge, and a Lorentz oscillator in order to account for the absorption in the material in the UV zone. This first step on the research project was carried out at Linköping University. 

    The second objective in the research project was to carry out additional studies on the samples received, in order to complement the information provided by the ellipsometry model and to improve the model itself, provided that it was possible. The characterization techniques used were X-ray diffraction, which made it possible to confirm that in fact boron nitride was present in the samples studied, and made it possible to verify the crystalline quality of the aforementioned samples, and in turn relate it to the quality of the ellipsometry spectra previously obtained; the Raman spectroscopy made it possible to further verify and compare the crystalline qualities of the samples received, as well as to obtain the frequency for the Raman active B-N stretching vibration in the basal plane, and to compare this value with that corresponding to the bulk sp2-boron nitride; scanning electron microscopy made it possible to observe the rough surface morphologies of the samples and thus relate them to some of the conclusions derived from the ellipsometry model; and finally cathodoluminescence measurements carried out at low temperature (4 K) allowed to obtain a broad band emission, on all the samples studied, which could be related to native defects inside the boron nitride layers, i.e., boron vacancies. Nevertheless, no trace of a free carrier recombination was observed. Considering that the hexagonal-boron nitride is nowadays considered to be a direct band gap semiconductor, it may be indirectly concluded, in principle, that the dominant phase present in the samples studied was the rhombohedral polytype. Moreover, it can be tentatively concluded that the lack of an observable interband recombination may be due to the indirect band gap nature of the rhombohedral phase of the boron nitride. Spectroscopic ellipsometry does not give a definite answer regarding this issue either, because the samples analyzed were crystalline by nature, thus not being possible to use mathematical expressions for the dielectric function models that incorporate the band gap value as a fitting parameter. Therefore, the nature of the band gap emission in the rhombohedral phase of the boron nitride is still an open research question. On the other hand, luminescent emissions originating from radiative excitonic recombinations were not observed in the cathodoluminescence spectra. This second step of the project was carried out at the Leroy Eyring Center for Solid State Science at Arizona State University.  

  • 7.
    Borgström, Fredrik
    et al.
    Linköping University, Department of Management and Engineering, Applied Thermodynamics and Fluid Mechanics.
    Coyet, Jonas
    Linköping University, Department of Management and Engineering, Applied Thermodynamics and Fluid Mechanics.
    Waste heat recovery system with new thermoelectric materials2015Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Increasing fuel prices, higher demands on "greener" transports and tougher international emission regulations puts requirements on companies in the automotive industry in improving their vehicle fuel efficiency. On a typical heavy duty Scania truck around 30% of the total fuel energy is wasted through the exhaust system in terms of heat dissipated to the environment. Hence, several investigations and experiments are conducted trying to find ways to utilize this wasted heat in what is called a waste heat recovery (WHR) system. At Scania several techniques within the field of WHR are explored to find the profits that could be made.

    This report will cover a WHR-system based on thermoelectricity, where several new thermoelectric (TE) materials will be investigated to explore their performance. A reference material which is built into modules will be mounted in the exhaust gas stream on a truck to allow for measurements in a dyno cell. To analyze new materials a Simulink model of the WHR-system is established and validated using the dyno cell measurements. By adjusting the model to other thermoelectric material properties and data, the performance of new TE materials can be investigated and compared with today’s reference material.

    From the results of the simulations it was found that most of the investigated TE materials do not show any increased performance compared to the reference material in operating points of daily truck driving. This is due to dominance of relatively low exhaust gas temperatures in average, while most advantages in new high performing TE-materials are seen in higher temperature regions. Still, there are candidates that will be of high interest in the future if nanotechnology manufacturing process is enhanced. By using nanostructures, a quantum well based BiTe material would be capable of recovering 5-6 times more net heat power compared to the reference BiTe material. Another material group that could be of interest are TAGS which in terms of daily driving will increase the power output with pending values between 40-80 %. It is clear that for a diesel truck application, materials with high ZT-values in the lower temperature region (100-350°C) must be developed, and with focus put on exhibiting low thermal conductivity for a wide temperature span.

  • 8.
    Tidholm, Johan
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Physics. Linköping University, Faculty of Science & Engineering.
    Thermodynamic and electronic properties of niobium at finite temperatures2015Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Niobium (Nb) is a fascinating element, that when it is in a solid state has remarkable properties. This is believed to be a result of its electronic configuration that has partially filled 4d and 5s sub-shells. Nb has a melting temperature of 2750 K, a high strength at high temperature, and a good wear resistance. Because of these properties, Nb is used as material for components of rockets and jet engines, and for strengthening steel.

    In the phonon dispersion relations, Kohn anomalies are experimentally observed to weaken with increased temperature, which is related to the superconducting properties of Nb. I include anharmonicity when I calculate the thermodynamic properties of Nb and relate this to the electronic structure.

    In this thesis I show that anharmonicity can not be neglected when considering thermodynamic properties of Nb. I observe broadening in the electronic band structure with increasing temperature, correlated with the gradual weakening of the Kohn anomalies in the phonon dispersion relations. Kohn anomaly in the phonon dispersion relation can be observed at 300 K and is completely absent at 1200 K. The observation of the Kohn anomaly's disappearance in the calculations is of great importance because it cannot be repeated by approaches that do not include anharmonic effects, meaning that properties that are directly related to phonon dispersion, like elastic constants, can be calculated more accurately with this approach.

  • 9.
    Nicollet, Andréa
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, Faculty of Science & Engineering. Grenoble INP Phelma.
    The influence of growth temperature on CVD grown graphene on SiC2015Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Graphene is one of the most popular material due to its promising properties, for instance electronics applications. Graphene films were grown on silicon carbide (SiC) substrate using chemical vapor deposition (CVD). Influence of the deposition temperature on the morphology of the films was investigated. Characterizations were done by reflectance mapping, atomic force microscopy and Raman spectroscopy. Two samples were done by sublimation process, to compare the number of layers and the morphology of the graphene films with the one grown by chemical vapor deposition.The reflectance mapping showed that the number of layers on the samples made by CVD was notinfluenced by the deposition temperature. But also, demonstrated that sublimation growth is present in allthe samples due to the presence of silicon coating in the susceptor. The growth probably started by sublimation and then CVD deposition. The step morphology characteristic of the silicon carbide substrate surface was conserved during the deposition of graphene. But due to surface step bunching, a decrease inthe step height occurred and the width of the terraces increased. The decreasing in deposition temperature leads to a smoother surface with the CVD method. Raman spectroscopy confirmed the presence ofgraphene and of the buffer layer characteristic of the sublimation growth. Moreover, it demonstrated the presence of compressive strain in the graphene layers.

  • 10.
    Lunden, Madelene
    Linköping University, The Tema Institute, Tema Environmental Change. Linköping University, Faculty of Arts and Sciences.
    An evaluation of a newly developed method with required beneficial qualities for measuring pCO2 from fresh water: Test-study performed in a small boreal stream network, south west of Sweden during March – October 2013 and 20142015Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Studies have concluded that streams emit CO2, which indicates that natural sources of Greenhouse Gases can contribute to climate changefeedback. Why this is of interest is to be able to make reliable climate models. These studies are however debated, since there are differentmethods to measure CO2 evasion from streams which conclude that different hydrological and chemical factors are affecting the gas exchange themost. It is based on an upside-down-placed chamber in the streams, containing a sensor which is able to directly measure the partial pressure ofCO2 (pCO2) in streams. An advantage with this method is that it is built on cheap equipment and therefore can be afforded to cover a bigcatchment with differing hydrological factors. The aim for the thesis is to evaluate the usefulness of this new method by running several statisticalanalyses on the collected data and also by comparing the trend from the statistical results to other methods statistical trends of pCO2. What can beconcluded by this study is that discharge affects the pCO2 in streams and it often appears with a negative correlation. Also, diurnal patterns ofpCO2 seem to appear, with a peak before lunch and minimum levels in the afternoon, which could indicate that pCO2 are dependent onphotosynthesis/respiration and/or temperature. These conclusions are of interest to understand how C acts in freshwater and respond to the climatechange. The study has to be extended with investigation of how more factors affect pCO2 and also some improvement for the method, before itcan be fully used.

  • 11.
    Nadhom, Hama
    Linköping University, Department of Physics, Chemistry and Biology, Biosensors and Bioelectronics. Linköping University, Faculty of Science & Engineering.
    Protein Microparticles for Printable Bioelectronics2015Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    In biosensors, printing involves the transfer of materials, proteins or cells to a substrate. It offers many capabilities thatcan be utilized in many applications, including rapid deposition and patterning of proteins or other biomolecules.However, issues such as stability when using biomaterials are very common. Using proteins, enzymes, as biomaterialink require immobilizations and modifications due to changing in the structural conformation of the enzymes, whichleads to changes in the properties of the enzyme such as enzymatic activity, during the printing procedures andrequirements such as solvent solutions. In this project, an innovative approach for the fabrication of proteinmicroparticles based on cross-linking interchange reaction is presented to increase the stability in different solvents.The idea is to decrease the contact area between the enzymes and the surrounding environment and also preventconformation changes by using protein microparticles as an immobilization technique for the enzymes. The theory isbased on using a cross-linking reagent trigging the formation of intermolecular bonds between adjacent proteinmolecules leading to assembly of protein molecules within a CaCO3 template into a microparticle structure. TheCaCO3 template is removed by changing the solution pH to 5.0, leaving behind pure highly homogenous proteinmicroparticles with a size of 2.4 ± 0.2 μm, according to SEM images, regardless of the incubation solvents. Theenzyme model used is Horse Radish Peroxidase (HRP) with Bovine Serum Albumin (BSA) and Glutaraldehyde (GL)as a cross-linking reagent. Furthermore, a comparison between the enzymatic activity of the free HRP and the BSAHRPprotein microparticles in buffer and different solvents are obtained using Michaelis-Menten Kinetics bymeasuring the absorption of the blue product produced by the enzyme-substrate interaction using a multichannelspectrophotometer with a wavelength of 355 nm. 3,3’,5,5’-tetramethylbenzidine (TMB) was used as substrate. As aresult, the free HRP show an enzymatic activity variation up to ± 50 % after the incubation in the different solventswhile the protein microparticles show much less variation which indicate a stability improvement. Moreover, printingthe microparticles require high microparticle concentration due to contact area decreasing. However, usingmicroparticles as a bioink material prevent leakage/diffusion problem that occurs when using free protein instead.

  • 12.
    Jungmalm, Kerstin
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, Faculty of Science & Engineering.
    Statistisk kvalitetsvärdering för optimering av processteg i aluminiumanodisering: Utvärdera avverkning på aluminiumdetaljer i avverkningsbad2015Independent thesis Basic level (professional degree), 10,5 credits / 16 HE creditsStudent thesis
    Abstract [en]

    The intention with this thesis was to evaluate how much pickling that have been achieved on aluminium details in the pickling bath before the anodization in an anodization process. As there were no earlier studies to use around pickling before anodization, statistical experimental design was chosen as planning tool. Statistical experimental design was used to plan the experiments in an organized way and to evaluate how the pickling process works together with the main effects and the interaction effects. Detailed scientific studies were performed on how aluminium is prepared and how the anodization process works. The studies were performed in reference books. Three different methods were designed. The first method, method 1, was based on a fractional factorial design with four design variables, temperature, sodium hydroxide and aluminium concentrations and the time the details was submerged into the pickling bath. The aluminium details was made from a square profile pipe. There was nine experiments performed in method 1. The measurements on the pickling was performed in two ways, first with a dial indicator where the pickling was compared with a reference surface before and after, and another method also performed with a dial indicator, where the measurements was performed over the edge between the pickled surface and the reference surface. A statistical control calculation was done on the surface smoothness of the square profile pipes. The control showed that the standard deviation was 11 µm. Method 2 was based on a complete factorial design where the design variables was temperature and the time the details was submerged into the pickling bath. All aluminium details were homogenous. There were seven experiments performed in method 2. The measurements on the pickling was performed in two ways, first with a dial indicator where the pickling was compared with a reference surface before and after, and another method also performed with a dial indicator, where the measurements was performed over the edge between the pickled surface and the reference surface. A statistical control calculation was done on the surface smoothness of the homogenous details. The control showed that the standard deviation was 14 µm. Method 3 was designed in a different way than method 1 and 2. In method 3 one experiment was performed and the design variable which was changed was the time when the details was submerged into the pickling bath. The aluminium details had the form of homogenous cubes. The measurements on the pickling was performed by measuring the weight of the details on an analytical scale before and after the pickling, and then calculate the pickling in µm in two different ways. The first way was to use the atomic radius of aluminium and the second way was to use the size of the unit cell of aluminium. The two first methods gave very different results than the third method. The result for method 1 showed very random values with great dispersion which resulted in a non-detectable pickling. The result for method 2 was very similar to the result from method 1, very random values with great dispersion and no pickling was detectable with any confidence. The result from method 3 gave a theoretical calculated result for the pickling, when the aluminium details was submerged in the pickling bath for 1 minute, and based on the atomic radius of aluminium, of 1,52 µm and with the same conditions but using the unit cell of aluminium showed a pickling of 1,62 µm. When the aluminium details were submerged in the pickling bath for 3 minutes, the theoretical calculation with the atomic radius of aluminium gave that the pickling was 4,51 µm and with the same conditions but using the unit cell of aluminium showed a pickling of 4,79 µm.

  • 13.
    Klarbring, Johan
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Physics. Linköping University, Faculty of Science & Engineering.
    A first-principles non-equilibrium molecular dynamicsstudy of oxygen diffusion in Sm-doped ceria2015Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Solid oxide fuel cells are considered as one of the main alternatives for future sources of clean energy. To further improve their performance, theoretical methods able to describe the diffusion process in candidate electrolyte materials at finite temperatures are needed. The method of choice for simulating systems at finite temperature is molecular dynamics. However, if the forces are calculated directly from the Schrödinger equation (first-principles molecular dynamics) the computational expense is too high to allow long enough simulations to properly capture the diffusion process in most materials.

    This thesis introduces a method to deal with this problem using an external force field to speed up the diffusion process in the simulation. The method is applied to study the diffusion of oxygen ions in Sm-doped ceria, which has showed promise in its use as an electrolyte. Good agreement with experimental data is demonstrated, indicating high potential for future applications of the method.

  • 14.
    Randell, Per
    Linköping University, Department of Management and Engineering, Applied Thermodynamics and Fluid Mechanics. Linköping University, The Institute of Technology.
    Numerical Simulation of Temperature and Velocity Profiles in a Horizontal CVD-reactor2014Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Silicon Carbide (SiC) has the potential to significantly improve electronics. As a material, it can conduct heat better, carry larger currents and can give faster responses compared to today’s technologies. One way to produce SiC for use in electronics is by growing a thin layer in a CVD-reactor (chemical vapour deposition). A CVD-reactor leads a carrier gas with small parts of active gas into a heated chamber (susceptor). The gas is then rapidly heated to high temperatures and chemical reactions occur. These new chemical substances can then deposit on the substrate surface and grow a SiC layer. This thesis investigates the effect of different opening angles on a susceptor inlet in a SiC horizontal hot-walled CVD-reactor at Linköping University. The susceptor inlet affects both the flow and heat transfer and therefore has an impact on the conditions over the substrate. A fast temperature rise in the gas as close to the substrate as possible is desired. Even temperaturegradients vertically over the substrate and laminar flow is desired. The CVD-reactor is modeled with conjugate heat transfer using CFD simulations for three different angles of the inlet. The results show that the opening angle mainly affects the temperature gradient over the substrate and that a wider opening angle will cause a greater gradient. The opening angle will have little effect on the temperature of the satellite and substrate.

  • 15.
    Jansson, Mattias
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, Faculty of Science & Engineering.
    Optical properties of free-standing cubic silicon carbide2015Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The properties of free-standing cubic silicon carbide for optoelectronic applications are explored in this work. The main focus of the work is on boron doped cubic silicon carbide, which is proposed as a highly useful material in several optoelectronic applications. The material is grown using sublimation epitaxy and the doped material is grown homoepitaxially on nominally undoped seeds. It is characterized using the experimental setups of photoluminescence spectroscopy, Nomarski interference spectroscopy and absorption spectroscopy.

    I have studied seed growth of nominally undoped cubic material on hexagonal (4H) substrates, and the influence on the grown material from the different faces of the substrate. It is found that it is not possible under the explored conditions to completely cover the growth area with the cubic polytype on the carbon face, but it can be done reproducibly on the silicon face. Reasons for this are discussed. Different doping setups are also explored. The influence on the material properties from growth conditions is explored. It is shown from absorption measurements that it is possible to grow boron doped cubic silicon carbide using this growth method, whereas optical microscopy studies show that the sample quality degrades with high doping concentrations.

    I have explored the luminescence properties of the material. No boron related emission is found with either room temperature or low temperature photoluminescence spectroscopy. Reasons for this are discussed using results from absorption measurements and optical microscopy.

  • 16.
    Lundberg, Peter
    et al.
    Department of Biochemistry, University of Sydney, Australia.
    Roy, Sushmita
    Frick Laboratories, Princeton University, USA.
    Kuchel, Philip W
    Department of Biochemistry, University of Sydney, Australia.
    Immobilization Methods for NMR Studies of Cellular Metabolism: A Practical Guide1994In: ImmunoMethods, ISSN 1058-6687, Vol. 4, no 2, 163-178 p.Article in journal (Refereed)
    Abstract [en]

    Nuclear magnetic resonance (NMR) can be used in a nondestructive manner to study cellular metabolism in intact cell samples such as a suspension of cells. However, many different cell types require a well-regulated medium that includes a buffered pH, as well as a continuous supply of oxygen. A series of methods that have been used for the maintenance of the extracellular conditions involves the immobilization of cells, followed by perfusion of the immobilized cell sample. NMR studies can then be performed for extended periods of time, as well as under sterile conditions. We discuss methodology, with perfused erythrocytes and thymocytes as specific examples.

  • 17.
    Enberg, David
    Linköping University, Department of Electrical Engineering, Automatic Control. Linköping University, The Institute of Technology.
    Performance Evaluation of Short Time Dead Reckoning for Navigation of an Autonomous Vehicle2015Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Utilizing a Global Navigation Satellite System (GNSS) together with an Inertial Navigation System (INS) is today a common integration method to obtain a positioning solution for autonomous systems. Both GNSS and INS have benefits and weaknesses where the best parts from both systems can be combined with a Kalman filter. Because of this complementary nature, it is of interest to look at the robustness of the positioning solution when the Global Navigation Satellite System is temporarily not available. The aim of the thesis has been to investigate different vehicle models and to evaluate their short-time performance using a Dead Reckoning approach. The goal has been to develop a system for a Heavy Duty Vehicle (HDV) and to find out for which time interval a specific model can stay within a certain range when the GNSS is lost. A GNSS outage could for example happen when driving on a highway and passing signs, bridges and especially when driving inside tunnels. Also, for a solution to become commercially interesting, it must be cheap. Therefore, is it common to use so called Micro-Electro-Mechanical-Systems (MEMS) sensors which are of low-cost but suffer from biases, scale factors and temperature dependencies which must be compensated for. The results from the tests show that some models are able to estimate the position with good precision during short time GNSS outages whereas other models do not deliver the required accuracy. The main conclusion is that care should be taken when choosing the vehicle model so that it fits its usage area and the complexity needed to describe its motion. There are also lots of parameters to look at when investigating the best solution, where modeling of the low-cost sensors is one of them.

  • 18.
    Skarped, Linnéa
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    Vertical stratification and species composition of Nymphalidae butterfly assemblages in tree-fall gaps and understory in Madidi National Park, Bolivia2014Independent thesis Basic level (degree of Bachelor), 180 HE creditsStudent thesis
    Abstract [en]

    Rainforest is a dynamic ecosystem where species are affected by numerous biotic and abiotic factors. One important abiotic factor for many species is the availability of sunlight. The understory habitat under the closed undisturbed canopy is comparably constant with regard to sunlight and therefore also humidity and temperature. The canopy regulates the amount of sunlight that will reach the ground, which means that changes in canopy cover will change the understory environment. The main natural disturbances that affect the structure of rainforest are tree falls, that resulting in tree-fall gaps. The aim of this study was to compare the vertical stratification and species composition of fruit-feeding Nymphalidae butterflies between tree-fall gaps of different sizes and undisturbed understory in a primary rainforest in Madidi National Park, Bolivia. Fruit-baited traps were suspended at ground level (2 m) and in canopy (10-15 m) in 5 tree-fall gaps and adjacent undisturbed understory, a total of 40 traps. There were more species rich assemblages in gaps both at ground level and in canopy, compared to understory. The data show that there are different species assemblages in tree-fall gaps, undisturbed understory, canopy and at ground level. The vegetation structure affected by the amount of sun light was an important factor affecting butterfly assemblages. There was a tendency that differences among gap assemblages increased with gap size. These results indicate the importance of the mosaic pattern caused by natural tree-fall gaps, they contain specific resources that favor different butterfly assemblages.

  • 19.
    Karczmarz, Veronika
    Linköping University, Department of Physics, Chemistry and Biology, Biology. Linköping University, The Institute of Technology.
    Thermal comfort in young broiler chickens (Gallus gallus domesticus) inferred from metabolic expenses.2014Independent thesis Basic level (degree of Bachelor), 10,5 credits / 16 HE creditsStudent thesis
    Abstract [en]

    The thermoneutral zone (TNZ) curve lies between the ambient temperatures (Ta) where an endothermic animal uses the least amount of energy to maintain a balance between the heat production from the animal’s own metabolism and the heat lost to the environment. If the animal is exposed to Ta’s over the upper critical temperature (UCT), which is the highest temperature that is still in the TNZ, the animals have to use energy to cool down. If they are exposed to temperatures lower than the lower critical temperature (LCT), which is the lowest temperature that is still in the TNZ, the animal have to use energy to warm up. In the present study oxygen consumption was measured at different Ta’s to determine the TNZ in two and three week old broiler chickens (Gallus gallus domesticus). Two different protocols were used and compared, a pseudorandom protocol in which chickens were exposed to seven temperatures in two hour periods for each run and a more typical progressive protocol in which Ta decreased gradually, one or two degrees per hour. The TNZ in two weeks old chickens was between 30.7 ˚C- 36.4 ˚C and between 28.8 ˚C- 32.7 ˚C in the three weeks old chickens. In chickens the TNZ shifts remarkably during the first few weeks of life towards lower temperatures as the animals acquire thermoregulatory competence. The method with a pseudorandom protocol takes more factors, like activity, into consideration than a typical progressive protocol.

  • 20.
    Myklebust, Andreas
    et al.
    Linköping University, Department of Electrical Engineering, Vehicular Systems.
    Eriksson, Lars
    Linköping University, Department of Electrical Engineering, Vehicular Systems.
    Dry Clutch Micro-Slip Control and Temperature ConsiderationsManuscript (preprint) (Other academic)
    Abstract [en]

    With an automatic clutch in the powertrain it is possible to micro-slip the clutch. Micro-slip is a continuous small slip in the clutch used to isolate the driveline from the oscillations in the torque produced by a combustion engine. A control structure has been designed for a micro-slip controller. The basic components are a Linear Quadratic (LQ) controller based on a linearized driveline model and an Extended Kalman Filter (EKF) that can compensate the torque request from the LQ controller for the thermal dynamics of the clutch. To remove some stationary errors, integral action has been added to the LQ controller by adding an extra state. An anti-windup scheme is used, and the additional parameters depend on clutch conditions. The reference slip value is set according to a derived formula for the flywheel-speed-oscillation amplitude together with a dynamic safety margin that can increase during transients. Altogether the controller has a simple structure and there should be no technical problems to implement it in a production vehicle. In simulations with transient torque, unknown road grades, and a mass parameter that has been varied by a factor of 2, the controller is able to follow the slip reference without locking up. The simulations are performed on a non-linear driveline model, previously validated with data, that has been augmented with a model for the oscillative torque produced by the engine in order to more accurately describe micro-slip conditions. The torque model is a sinusoidal model and has been fitted to high resolution data. The oscillation amplitude and frequency agree well with the data. The thermal behavior of a clutch with micro slip is analyzed and the EKF should be used for temperature surveillance together with some suggested counter measures although there were no excessive temperatures during simulations of recorded driving missions. However, the simulations show that the fuel consumption increase might be too large for a heavy-duty-truck application if micro-slip control is to be used at all operating conditions. Further analysis of costs versus benefits are required on a vehicle level but the feasibility of a micro-slip control system for a dry clutch truck has been proven.

  • 21.
    Saarinen Claesson, Per
    Linköping University, Department of Physics, Chemistry and Biology, Biology. Linköping University, The Institute of Technology.
    Fisk- och fågelpredations påverkan på den bentiska makroevertebratfaunans sammansättning under tidig vår i Tåkern2012Independent thesis Basic level (degree of Bachelor), 10,5 credits / 16 HE creditsStudent thesis
    Abstract [en]

    Predation is one of many factors that form the structure of the macroinvertebrate community in lakes, wetlands and watercourses. Earlier studies lack an examination concerning how fish- and waterfowl predation affect macroinvertebrates during shorter periods in the spring. I performed an exclosure study in the shallow eutrophic Lake Tåkern which is located in the western part of Östergötland County, Sweden. The experiment was performed during a three week period (1-21 April 2012) when the water temperature was low and the density of migrating diving ducks was high. The experimental cages used included three out of four different treatments; general predation (open cages), bird exclusion (net with mesh size 90*45mm) and no predation (net with mesh size 1*1mm). In the fourth treatment, which was used to control for cage effects, samples were collected outside the cages. The cages where placed in blocks three and three, one for each the three treatments, on eight different locations in the experiment area. No significant difference was detected between the different treatments concerning diversity (Shannon diversity index: F3,25=1,39; P=0,27 and Simpson diversity index: F3,25=1,47; P=0,25), taxonomic richness (F3,25=1,74; P=0,19) nor density (F2,25=0.41; P=0,75) of the macroinvertebrate fauna. The lack of effect from predation of fish is most likely explained by the low water temperature during the experiment period. The lack of effect from waterfowl predation is most likely due to a low density of diving ducks, despite the season.

  • 22.
    Khajavizadeh, Lida
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    Growth and structural characterization of ScN/CrN periodic and quasi-periodic superlattices for thermoelectric application2014Independent thesis Advanced level (degree of Master (Two Years)), 30 credits / 45 HE creditsStudent thesis
    Abstract [en]

    The aim of this diploma work is the deposition and characterization of ScN/CrN superlattices with both periodic and quasi-periodic structures. ScN as semiconductor material with (2eV) band gap energy was selected due to its thermal and mechanical stability and its hardness. High resistivity against oxidation and high wear resistance were the reasons for choosing CrN as another candidate for the superlattices. The Rudin Shapiro structure was selected as quasi-periodic structure because of its more random structure.

    In this research both periodic and Rudin Shapiro as quasi-periodic structures have been deposited and investigated. The best optimized temperature for the deposition was 835°C and the selected periodic thickness was 6 nm for periodic structure with each ScN and CrN layers having each a thickness of 3 nm. The material ratio of Rudin Shapiro superlattices was kept the same as periodic samples. Evaluation of quasi-periodic and periodic superlattices was performed by X-ray diffraction measurements. Five peaks were recorded for superlattices measurement of periodic structure by diffraction. The envelope of the diffraction pattern represents two separated peaks in investigation of Rudin Shapiro investigation.

    The results of the X-ay measurements showed low quality of the superlattices for both deposited structures which suggest the need for further optimization of the deposition process or the use of other materials of superlattices.

  • 23.
    Chen, Huijuan
    et al.
    Linköping University, Department of Management and Engineering, Energy Systems.
    Janbakhsh, Setareh
    Linköping University, Department of Management and Engineering, Energy Systems.
    Larsson, Ulf
    university of Gavle.
    Moshfegh, Bahram
    Linköping University, Department of Management and Engineering, Energy Systems.
    Comparisons of ventilation performance of different air supply devicesin in an office environmentManuscript (preprint) (Other academic)
    Abstract [en]

    The aim of this study was to compare ventilation performance of four different air supply devices in an office environment with respect to thermal comfort, ventilation efficiency and energy-saving potential, by performing numerical simulations. The devices have the acronyms: Mixing supply device (MSD), Wall confluent jets supply device (WCJSD), Impinging jet supply device (IJSD) and Displacement supply device (DSD). Comparisons were made under identical set-up conditions, as well as at the same occupied zone temperature of about 24.2°C achieved by adding different heat loads and using different air-flow rates. Energy-saving potential was addressed based on the air-flow rate and the related fan power required for obtaining a similar occupied zone temperature for each device.

     

    Results showed that the IJSD could provide an acceptable thermal environment while removing excess heat more efficiently than the MSD, as it combined the positive effects of both mixing and stratification principles. This benefit also meant that this device required less fan power than the MSD for obtaining equivalent occupant zone temperature. The WCJSD studied in this paper behaved somewhat like the MSD, but caused higher draught discomfort at ankle level because of very high supply velocities, which was might due to small nozzle diameter of the supply device. Further studies are required for the WCJSD to make these conclusions applicable for general conditions. The DSD showed a superior performance on heat removal, air exchange efficiency and energy saving to all other devices, but it had difficulties in providing acceptable vertical temperature gradient between the ankle and head levels for a standing person.

  • 24.
    Saleem, Hassan
    Linköping University, Department of Physics, Chemistry and Biology, Nanostructured Materials. Linköping University, The Institute of Technology.
    Thermal Stability of cubic and nanocrystalline arcevaporated TiCrAlN coatings2014Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    (TixCryAlz)N coatings were deposited on WC-Co substrate using cathodic arc evaporation technique to investigate phase transformation, thermal stability, and high temperature mechanical properties. Two compositions Ti0.34Cr0.33Al0.33N and Ti0.24Cr0.02Al0.74N were studied and compared with industrial standard hard TiAlN coating. These compositions were annealed at 800 oC up to 1100 oC. X-ray diffractogram showed a mixture of cubical and hexagonal phases in as-deposited state for high Al content composition. Differential scanning calorimetry showed that spinodal decomposition starts late compared to TiAlN coating. The results from nanoindentation did not show age hardening in Ti0.34Cr0.33Al0.33N composition while composition Ti0.24Cr0.02Al0.74N showed a significant increase in hardness compared with TiAlN coating. Also the Ti0.24Cr0.02Al0.74N retains its hardness over a wide temperature range while TiAlN coating hardness decreases after annealing at 900 oC. Upon annealing at 1400 oC, the coating decomposes into equilibrium phases i.e., c-TiN and h-AlN while Cr found to be in oxides form. HRTEM results revealed that the coating consists of nanocrystalline grains with defects rich regions.

  • 25.
    Persson, Emma
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, The Institute of Technology.
    Printed Schottky Diodes based upon Zinc Oxide Materials2013Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The aim of this master thesis was to develop a process for fabricating Schottky diodes, using techniques that are suitable for cheap large volume mass production e.g. printing, with tetrapod structured ZnO as the semiconductor. Part of the work involved selecting suitable metals for ohmic and Schottky contact and identification of a binder that can be used for dispersion of the Zinc Oxide (ZnO). ZnO is a II-VI compound semiconductor with a wide band gap (3,4 eV). The Schottky diode is used as a rectifier. A rectifier serves the purpose to turn Alternating Current (AC) to Direct Current (DC). The Schottky diode should only conduct current in the forward direction, in the reverse direction the current should be blocked. In this thesis printed diodes were used to construct different types of rectifiers for example half wave rectifiers and full wave rectifiers. Aside from electrical properties, adhesion properties have also been investigated. Adhesion was showed to depend on not only the choice of binder, but also UV-dose and annealing temperature. Aluminum and silver together with ZnO proved to be the best materials combination with a rectification ratio up to 105−106. Different sizes of Schottky diodes were printed and the smaller diodes with an area of 0,5x0,5mm^2 performed best as a half wave rectifiers while the larger size,1x1mm^2, performed best as a full wave rectifier.

  • 26.
    Tiwari, Ashutosh
    Linköping University, Department of Physics, Chemistry and Biology, Biosensors and Bioelectronics.
    TEMPERATURE-GATED SWITCHABLE BIOELECTROCATALYTIC INTERFACE2013Conference paper (Refereed)
  • 27.
    Zenkevich, E.I.
    et al.
    National Technical University of Belarus, Department of Information Technologies and Robotics, Minsk, Belarus.
    Blaudeck, T.
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, The Institute of Technology.
    Kowerko, D.
    University of Zürich, Institute for Inorganic Chemistry, Zürich, Switzerland.
    Stupak, A.P.
    Institute of Physics, National Academy of Science of Belarus, Minsk, Belarus.
    Cichos, F.
    Leipzig University, Institute of Experimental Physics I, Molecular Nanophotonics, Germany.
    C. von, Borczyskowski
    Institute of Physics and Center for Nanostructured Materials and Analytics (nanoMA), Chemnitz University of Technology, Chemnitz, Germany.
    Ligand exchange dynamics and temperature effects upon formation of nanocomposites based on semiconductor CdSe/ZnS quantum dots and porphyrins: Ensemble and single object measurements2012In: Macroheterocycles, ISSN 1998-9539, Vol. 5, no 2, 98-114 p.Article in journal (Refereed)
    Abstract [en]

    Dye molecules with pyridyl side substituents (porphyrins and heterocyclic perylene diimides) coordinatively attached to semiconductor CdSe/ZnS quantum dots (QDs) surface form quasi-stable QD-Dye nanocomposites of various geometry in the competition with capping molecules (tri-n-octyl phosphine oxide or long chain amines) exchange. This results in photoluminescence (PL) quenching of the QDs both due to Foerster resonance energy transfer and formation of non-radiative surface states. QD surface is inhomogeneous with respect to the involved attachment and detachment processes. The formation of QD-Porphyrin nanocomposites is realized at least two time scales (60 and 600 s), which is attributed to a reorganisation of tri-n-octylphosphine oxide capping shell. In a low temperature range of 220÷240 K related changes in QD absorption and emission reveal a phase transition of the capping shell (tri-n-octyl phosphine oxide and amine). In QD-Dye nanocomposites, this phase transition is enhanced considerably by only a few attached dye molecules and has impact on the QD core structure followed by changes of PL quenching and exciton-phonon coupling. A combination of ensemble and single molecule spectroscopy of QD-Dye nanocomposites reveals that few or even only one attached dye molecule change the surface distribution and energy of dye related surface trap states considerably. © ISUCT Publishing.

  • 28.
    Carlström Ödegaard, Anja
    et al.
    Linköping University, Department of Medical and Health Sciences, Division of Nursing Science. Linköping University, Faculty of Health Sciences.
    Nilsson, Tim
    Linköping University, Department of Medical and Health Sciences, Division of Nursing Science. Linköping University, Faculty of Health Sciences.
    Differenser av kroppstemperaturen hos patienten i samband med anestesi och operation2013Independent thesis Advanced level (degree of Master (One Year)), 10 credits / 15 HE creditsStudent thesis
    Abstract [sv]

    Bakgrund: Kroppstemperaturen skall mätas under de flesta generella anestesier föratt upptäcka hypotermi och hypertermi. Vid anestesi sjunker kroppstemperaturen.Peroperativ hypotermi har negativa konsekvenser för patienten.Anestesisjuksköterskan ansvarar för att övervaka patientens temperatur underanestesi.

    Syftet med studien var att utifrån litteraturen evaluera temperaturskillnaderperoperativt vid mätning av kroppstemperaturen på olika mätplatser hos patienten.

    Metod: Studien är en litteraturstudie med systematisk ansats. Artikelsökningarutfördes i PubMed, Cinahl och Scopus. Temperaturskillnaderna redovisas sommedelvärde, gräns för överensstämmelse ±1,96 SD och 95 % konfidensintervall.

    Resultat: Efter kvalitetsgranskning inkluderades 23 artiklar. Resultatet är indelat itre kategorier: Temperatur vid bukkirurgi, temperatur vid kardiopulmonell bypasssamt temperatur vid övrig kirurgi. Alla studier, förutom en som utfördes iepiduralanestesi, utfördes i generell anestesi. Antal mätplatser i studierna var 18stycken. Det fanns temperaturskillnader mellan mätplatserna. De störstatemperaturskillnaderna sågs vid kardiopulmonell bypass.

    Konklusion: Att vara kritisk vid temperaturmätning vid anestesi är viktigt dåmätplatsernas temperaturer kan variera mycket. Att mäta patientenskroppstemperatur peroperativt är av vikt för att upptäcka hypotermi respektivehypertermi, som båda har negativa konsekvenser och kan innebära ett stort lidandeför patienten. Temperaturmätning bör få större fokus inom anestesin och därmed kanpatientsäkerheten ökas vid anestesi.

  • 29.
    Radpour, Houtan
    Linköping University, Faculty of Arts and Sciences. Linköping University, The Tema Institute.
    Diel and monthly observations of plant mediated fluxes of methane, carbon dioxide and nitrous oxide from lake Följesjön in Sweden using static chamber method2013Independent thesis Advanced level (degree of Master (Two Years)), 80 credits / 120 HE creditsStudent thesis
    Abstract [en]

    Aquatic plants or macrophytes are known as conduits of Methane (CH4), Carbon dioxide (CO2) and Nitrous oxide (N2O) which contribute to the total fluxes of the Greenhouse gases emissions from lakes. Recent studies emphasized that the knowledge on plant mediated emissions calls for more systematic and comparative data especially in the areas of spatial and temporal variability. In this study I measured diel (24 hour) and diurnal(  daily hours only) plant mediated fluxes during four sampling sessions using chamber method from a  Swedish lake in summer 2012. The measurements were conducted on two macrophyte population patterns of mixed plant communities and Equisetum fluviatile (specie-specific) community. CH4 emissions were higher in darker hours and there were no diel correlation between CH4 fluxes and average diel temperature. CH4 fluxes varied between 0.42 mmol m-2d-1 and 2.3 mmol m-2d-1. The CO2 fluxes had negative fluxes in day and positive during the day which was logical due to macrophyte respiration and photosynthesis mechanisms. Occasional daily positive fluxes were seen (only) during the rainy hours and there were no correlation between temperature and diel CO2 fluxes. The total net CO2 exchange was 2.8mmol m-2d-1 indicating that there was more CO2 release in the littoral zone of that lake. N2O fluxes did not show any clear diel or monthly pattern and the fluxes ranged between positive and negative numbers. The N2O fluxes did not exceed 2µmol m-2 d-1 with the total average flux of 0.8µmol m-2 d-1.

  • 30.
    Wadeasa, Amal
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Charge transport in low-band gap polymers studied with the CELIV technique2005Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Charge transport is one of the most important properties in both organic and inorganic opto-electronic devices. Few experimental methods are typically used to measure this parameter in organic materials field, such as Time of flight method (TOF) and the recently proposed charge extraction in linear increase voltage (CELIV).

    In this project, we aim to design the experimental setup for the CELIV method in the laboratory at ITN. The thesis starts with simple definition for the conjugated polymers and materials used and then describe the theoretical part of the method to be able to extract some important parameters such as sample thickness, mobility, conductivity and electric field. The estimation of the thickness of the sample is compared with other well-established techniques as X-ray diffraction (XRD), Atomic force microscope (AFM), Ellipsometery and DekTak. Measured values of mobility and conductivity are compared to TOF results. We vary different parameters, such as polymer solution concentration, input bias, delay time, temperature and electric field. Poly (3-hexyl thiophene) or P3HT and Poly (Para-Phenylenevinylene) or PPV are the polymers characterized in this project because they have different chemical properties (side group) and physical one (regularity of the chain) and they are well-studied materials via other techniques.

  • 31.
    Kiland, David
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    USB communication2005Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    University. The purpose of this work was to examine the possibility to replace an older serial interface to a computer by the newer Universal Serial Bus (USB).

    The report describe in detail the theory behind communication between a computer and a USB device, everything from signaling to data transfer. It mainly describes how USB handle a mass storage device connected to a computer. It also handles the possibility to implement a mass storage device and use the Universal Serial Bus with a small 8-bit microcontroller from Microchip.

    The implementation has been made on a data logger, a small device which task is to measure the temperature with a specified interval over a longer time and store it into a memory. The thesis work has been carried out at Eltex Of Sweden in Älmhult, Sweden.

  • 32.
    Lindehammar, Christian
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Mätdatasystem för testning av betongslipmaskiner2005Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    This thesis work was made for HTC Sweden AB in Söderköping. The company develops and produces floor grinding systems. The task was to find suitable equipment for surveillance and to log data from the grinders. The interesting areas to measure were: temperature, current, revolutions per minute, wear on the tools and air moisture.

    The equipment was purchased and it consisted of sensors, data loggers and a data acquisition card. The project had a budget of 20 000 SEK. Software used was the demo version of LabVIEW and a full version of EasyView. To be able to log and survey data from the sensors a program was created in LabVIEW and a successful test run was made.

  • 33.
    Andersson, Johan
    et al.
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Rosén, Lars
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Tekniska aspekter vid katalogframtagning2005Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The goals of this thesis are to examine the technical aspects of catalogue production and to create a product catalogue for Westerbergs Repslageri. The company’s purpose with this catalogue is to market their new brand Swedish Rope and use it as a ground for sales. Since the catalogue is to be used for sales, it is important that the colors of the products in the catalogue are as authentic as possible.

    To achieve correct colors in the product images, a good understanding in color management is needed. Every unit, such as camera, computer screen and printer, interprets colors in its own way, which leads to complications in maintaining the original color during the process. Accurate color interpretation demands well calibrated units with profiles and a color management system to handle the converting between the different color gamuts of the units.

    An effective communication with the catalogue readers is reached by adjusting the layout and the information to the target group. By combining typography, images and layout with an artistic approach a good visual communication is achieved.

    The thesis describes the production flow from studio photography to the printable catalogue. The flow includes digital photography, image processing, layout and print preparation.

    The following conclusions have been made through theoretical studies, practical trials and visual assessment:

    • To get good color reproduction, lighting sources with the same color temperature should be used. The color temperature is compensated with adjusted profiles, developed for the specific lighting condition.

    • A perfect color reproduction can never be reached throughout the entire production flow. This is due to the different units limited ability to reproduce colors. Since the colors are converted between the color gamuts of the units, the exact color can never be reproduced.

    • Every unit in the process should have profiles that are adjusted and calibrated in order to produce a color as similar to the original as possible.

    • The printer has specific demands regarding format, fonts and separation of colors.

  • 34.
    Malvestam, Daniel
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Implementation of an In-situ Non-contact Temperature Controller for Active Thermal Fatigue Tests of Power Electronics2006Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    A controller with thermopile IR-sensors is developed to monitor and control the temperature of power electronics during active accelerated thermal fatigue tests - power cycling. Bond wiring is the dominating method for connecting semiconductors to the package leads, distance points on a chip or chip modules within a package. 25-30\% of all package related failures of electronic devices during their operation life time can be related to bond wire failures.

    To test bond wires, power cycling test can be performed to stimulate failures in bond wire connections, enabling for further development and improvements in the area of bond wires. At IMTEK (Department for microsystems engineering) University of Freiburg, new types of aluminium/copper fibre-reinforced bond wires with a diameter 300 micrometers for power electronics are tested together with a power cycling equipment. During a power cycling test the component is periodically heated, with a current flow through the chip, and cooled down.

    These new bond wires are bonded on IGBT (Insulated Gate Bipolar Transistor) modules. Since it is possible to measure the overall temperature (mean value) of the chip, using IR-sensors, the developed´controller in this final thesis is robust. Further, the implemented controller can easily be extended for power cycling with e.g. 10 modules in parallel.

  • 35.
    Khan, Muhammad Awais
    Linköping University, Department of Computer and Information Science, Statistics. Linköping University, The Institute of Technology.
    Isolating and quantifying factors affectingbody and paint business for Volvo Cars2013Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    This thesis focuses on identifying the degree of contribution of the most important factors affecting Body and Paint business of Volvo Car Corporation in Sweden. It is clear that Body and Paint business for VCCS directly depends on the number of registered accidents. Our major purpose is to determine the factors which have direct or indirect effect on reduction in the number of accidents in Sweden and to analyze in which degree they may affect the business. During the interviews with senior staff members, we discover that particularly city safety cars are mentioned by most of the specialists. Other important factors highlighted were mileage, weather, company car/ private car and age of a car.

     

    City Safety is a technology designed to help the driver mitigate, and in certain situations avoid, collisions at low speed by automatically bracking the vehicle. The estimated claim rate frequency i.e. claims per contract rate was 50% lower for city safety equipped; then other warranty cars models without system. The study also analysis the effect of rain, mean temperature and snow on Volvo Body part sales in Stockholm Sweden. Temperature snow impacted road accidents significantly. Snow was shown to be the leading variable, as the number of accidents increases sharply with increased snowfall. Temperature is the second important variable in the list i.e. as the temperature decreases by 1ͦC the sales of body and paint business in Stockholm increases by 1.6%.

     

    Time variable such as weekday, month, and year also plays significant role in this model. During Fridays 51% high accidents are expected then accidents occurred on Sundays.

  • 36.
    Rashid, Asim
    et al.
    Tekniska Högskolan, Högskolan i Jönköping, JTH. Forskningsmiljö Produktutveckling - Simulering och optimering.
    Strömberg, Niclas
    Tekniska Högskolan, Högskolan i Jönköping, JTH. Forskningsmiljö Produktutveckling - Simulering och optimering.
    Sequential simulation of thermal stresses in disc brakes for repeated braking2013In: Proceedings of the Institution of mechanical engineers. Part J, journal of engineering tribology, ISSN 1350-6501, E-ISSN 2041-305X, Vol. 227, no 8, 919-929 p.Article in journal (Refereed)
    Abstract [en]

    In this paper, an efficient sequential approach for simulating thermal stresses in brake discs for repeated braking is presented. First, a frictional heat analysis is performed by using an Eulerian formulation of the disc. Then, by using the temperature history from the first step of the sequence, a plasticity analysis with temperature dependent material data is performed in order to determine the corresponding thermal stresses. Three-dimensional geometries of a disc and a pad to a heavy truck are considered in the numerical simulations. The contact forces are computed at each time step taking the thermal deformations of the disc and pad into account. In such manner, the frictional heat power distribution will also be updated in each time step, which in turn will influence the development of heat bands. The plasticity model is taken to be the von Mises yield criterion with linear kinematic hardening, where both the hardening and the yield limit are temperature dependent. The results show that during hard braking, high compressive stresses are generated on the disc surface in the circumferential direction which cause yielding. But when the disc cools down, these compressive stresses transform to tensile residual stresses. For repeated hard braking when this kind of stress history is repeated, we also show that stress cycles with high amplitudes are developed which might generate low cycle fatigue cracks after a few braking cycles.

  • 37.
    Nasef, Hany
    et al.
    Universitat Rovira i Virgili.
    Beni, Valerio
    Universitat Rovira i Virgili.
    O´Sullivan, Ciara K.
    Universitat Rovira i Virgili.
    Electrochemical melting-curve analysis.2010In: Electrochemistry communications, ISSN 1388-2481, E-ISSN 1873-1902, Vol. 12, 1030-1033 p.Article in journal (Refereed)
    Abstract [en]

    Genotyping technologies need to tackle issues of cost-effectiveness, flexibility, and mutiplexability to meetthe ever-increasing demands for clinical diagnostics, addressing the future medical paradigm. Here wereport on a facile method for the rapid detection of mutations using electrochemical melting-curve analysis.The concept is based on the use of an immobilised probe hybridised to the mutant region of a ferrocenelabelled amplicon. Following hybridisation, the temperature is ramped and the dissociation of the ferrocenelabelled DNA from the electrode surface is monitored using differential pulse voltammetry. Using a modelsystem consisting of short probe and target, the proposed approach was demonstrated to clearlydiscriminate between complementary and mismatch duplexes. The melting temperature of the surfaceconfined DNA duplex was observed to be markedly lower than that obtained in solution, with meltingtemperatures of 38 and 59 °C, observed, respectively. The approach can be extended to array based meltingcurveanalysis, allowing the simultaneous detection of multiple mutations, as well as for genosensor design.

  • 38.
    Bexell, Jonas
    et al.
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Bjureus, Erik
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    A study of energy exchange in earth air tubes2010Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    As energy issues today are of great interest the writers of this report have done a research about an alternative to save energy by reducing the cost of preheating the outdoor air.

    By taking the outdoor air to the ventilation system via a pipe buried in the ground, you can preheat the outdoor air, which, in turn, could save energy. By doing this you do not have to bring as much energy to preheat the supply air, to get the desired supply air temperature. The report also explains if the earth air tubes are a good complement to the mechanical ventilation system with a heat exchanger.

    The report begins with describing briefly the history of ventilation systems in use today. It also describes the functions of the system and show to the reader how two of the installation layouts looks like.

    The writers using the project Daggkåpan in Linköping as a basis for the investigation and they also provide an alternative solution to the existing ventilation system.

    This report also demonstrate the factors that come into play to get as much energy exchange as possible, and what problems may arise with this type of complement to the ventilation system with a heat exchanger.

    Trough optimization of the earth air tubes and depending on which energy source is in use, you can actually save energy and by that also money. The factor that proved to bethe most significant for the energy exchange was the pipe length. Other factors such as trench depth, pipe diameter and the air flow has been shown to play a smaller role in how much energy you can save.

    Finally the report ends with the writers own reflections and a discussion based on the results.

  • 39.
    Jansson, Anders
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Gyrostudy - Development of a gyroplatform2007Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    This master thesis has been carried out at Avantel AB where the assignment was to design hardware and software and with the aid of these collect data from gyro sensors. Because the industry demands lesser and cheaper sensors with increased precision new methods compensating for drift and temperature sensitivity are required. Methods that necessitate extensive evaluation and testing.

    The project began with a market overview of existing gyro sensors where certain characteristics such as drift and offset were examined. The next phase included design of hardware where amplifiers, power supply and A/D conversion are the major parts. Also, Universal Serial Bus, USB were implemented for connectivity. Software with the purpose of controlling the USB circuit and writing collected data to file was developed.

    This project run from September 2006 to January 2007 with the result of a working measurement instrument and collected data according to the criteria’s that was set.

  • 40.
    Nordlander, Johan
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Data collection for an individual heat consumption measurement system using a Zigbee wireless network2007Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Individual heat/energy measurements have been a hot topic in Europe during the last 50 years, both for fair reasons and for energy saving reasons. The argument for using individual heat/energy measurements for fair reasons is that no one should pay more than he or she consumes no matter if the person lives in a rental apartment or in a house. Previous studies have shown that individual heat/energy measurements will lower the total energy consumed, when each tenant of a multi-apartment building has to pay for the actual amount of the consumed heat/energy individually.

    Unfortunately the installation cost of an individual heat/energy measurement system is considered to be high, so the economical arguments for installing this type of system in existing and new buildings have not been fullled. One reason for this is that until recently all of these systems used wired solutions. However the publication of the two wireless standards ZigBee and Zwave have opened new possibilities for creating entirely standardized wireless systems, reducing both the installation time and cost.

    The goal of this thesis work is to evaluate the possibilities for developing such a system based on the ZigBee standard. The work began with a study of the existing systems (hardware systems) available from some companies in Sweden (Brunata, Metrima, Siemens Building Technologies and Techem). This work also covers some communication protocols used (M-bus, BACnet, ZigBee) and dierent sensors (temperature, humidity, water consumption, and heat) used in an individual heat/energy measurement system.

    Based on this information a central data collection software server for windows has been developed. This together with a client application and a database server gives an entire software suite for data collection and data analysis of a ZigBee based heat/energy measurement system.

  • 41.
    Klein, Daniel R.
    Linköping University, The Tema Institute, Department of Water and Environmental Studies. Linköping University, Faculty of Arts and Sciences.
    The electricity system vulnerability of selected European countries to climate change: A comparative analysis2012Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The electricity system is particularly susceptible to climate change due to the close interconnectedness between not only electricity production and consumption to climate, but also the interdependence of many European countries in terms of electricity imports and exports. This study provides a country based relative analysis of a number of selected European countries’ electricity system vulnerability to climate change. Taking into account a number of quantitative influencing factors, the vulnerability of each country is examined both for the current system and using some projected data. Ultimately the result of the analysis is a relative ranked vulnerability index based on a number of qualitative indicators. Overall, countries that either cannot currently meet their own electricity consumption demand with inland production (Luxembourg), or countries that experience and will experience the warmest national mean temperatures, and are expected to see increases in their summer electricity consumption are found to be the most vulnerable for example Greece and Italy. Countries such as the Czech Republic, France and Norway that consistently export surplus electricity and will experience decreases in winter electricity consumption peaks were found to be the least vulnerable to climate change. The inclusion of some qualitative factors however may subject their future vulnerability to increase. The findings of this study enable countries to identify the main factors that increase their electricity system vulnerability and proceed with adaptation measures that are the most eective in decreasing vulnerability.

  • 42.
    Ringdahl, Tony
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Stiffening of roof trusses due to lateral forces2007Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    This final thesis has its origin due to Derome trätekniks wish to investigate if it’s possible to ensure total stability of the roof construction for their future hall concept Deromehallen. The stabilization is either made with the help of diaphragm action or with a system of parallel trusses.

    In the background there are the stabilization problems with Lidl‐stores. These roofs were tiled roofs which were edified of roof cloth, ridges and bricks. The roof trusses showed buckling in top and sub frames, which in some occasions demanded action to prevent the roof from collapsing.

    The problem with these halls is that the lateral forces on the roof construction are big and have to be stabilized (this concerns only span lengths about 25 meters). This happens when the load from snow affect roof trusses top frames and creates large axial forces which on their hand gives lateral buckling. The ridges opportunities to absorb these forces by themselves are small. If a top frame buckles the ridge this will affect the next roof truss and this will buckle the next ridge force including its own which does that these forces are added for every roof truss. The result is that a small force fastly becomes a big one.

    Diaphragm action with help from trapezoidal corrugated sheets is designed after the presuppositions described in method part (see chapter 3.2) and roof sheet Plannja 70 were picked. Due to that this hall building is uninsulated but the choice of roof plate is not optimized with the motivation that it is an unsureness when diaphragm action and temperature movements coexists.

    The difference between roofs covered with tiles and cardboards is that the tiled roof has ridges instead of matchboards. The stabilization system consists of parallel trusses, wind straps, jack rafters and ridges or matchboards. Wind straps and jack rafters are designed according to BKR 03 while parallel trusses and ridges are designed according to Eurocode 5 part 1:1.

    This stabilization system skeleton (parallel trusses, wind straps, jack rafters and ridges or matchboards) is designed to hold expected forces and a construction is never stronger than it´s weakest link. All fasters and fastening details (nails and angels) have to be designed before the system are complete; this is not included in this final thesis.

  • 43.
    Hegen, Peter
    Linköping University, Department of Computer and Information Science. Linköping University, The Institute of Technology.
    Continuous Measurements of Core Body Temperature using Body Sensor Networks2012Independent thesis Advanced level (degree of Master (One Year)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Long-term body temperature measurements for research and diagnosis are currently done in hospitals or specialized research labs. This method has several drawbacks: the use of wired ob- trusive sensors (e.g., rectal probes to measure the core body temperature) may be uncomfortable for patients. Furthermore, situations recorded in laboratory settings do not reflect reality as patients are not subject to their normal living environment. Furthermore, it is labor-intensive to regularly check upon patients and care for their well-being. Using small wireless sensor nodes in a body sensor network to measure body functions, one can mostly offset the limitations listed above.

    For this work, we have developed a wireless sensor node that uses an infrared thermopile as a sensor to unobtrusively measure the core temperature at the tympanic membrane. Due to their construction, these sensors are heavily dependent on the ambient temperature in the surroundings of the sensor packaging. While this does not affect their use in single-shot measurements (e.g., using an ear thermometer), it poses a challenge for continuous measurements, as common living environments do not have constant ambient air temperatures and people frequently commute between different places. These conditions may offset measurements significantly, an important problem for medical applications that require high accuracy.

    In this work, we employ infrared thermopiles in a body sensor network and characterize their behaviour in various situations, especially in the presence of varying environmental conditions. Based on our observations, we describe methods for post-processing measurements in order to compensate environmental changes and hence get results reflecting reality more closely. Our evaluation shows that these methods can offset the infrared thermopile’s weakness but need further work to achieve the degree of accuracy that is needed for medical applications. 

  • 44.
    Hamedi, Naser
    Linköping University, Department of Management and Engineering, Applied Thermodynamics and Fluid Mechanics. Linköping University, The Institute of Technology.
    Numerical Study of NOx and Flame Shape of a DLE Burner2012Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    For natural gas combustion, there is a large amount of experience in the gas turbine industry. However, much of the design work is based on costly combustion tests due to insufficient accuracy of existing prediction tools for data such as emissions and effects due to fuel composition. In the present work, Computational Fluid Dynamics (CFD) approach is used to study partially premixed combustion in the 3rd generation DLE (Dry Low Emission) burner that is used in SGT-700 and SGT-800 gas turbines. The fuels that are studied here are natural gas and enriched hydrogen fuel. The CFD models which are used in this work are an axisymmetric and a 3D model and the softwares are ANSYS CFX and ANSYS FLUENT.

    One of the main objectives of this thesis is the study of flame shape and NOx emission in hydrogen enriched combustion. In the first study of the present work, effect of adding hydrogen to non-preheated gas combustion was investigated and the results were compared with the available measurement data. Calculated laminar burning velocity with CANTERA showed a good agreement with the experimental and numerical references. Also, the accuracy of generated flamelet libraries in CFD tools to calculate adiabatic flame temperature was compared with different available tools. Results showed good agreement between available tools for the ranges of interest.

    In addition, flame shape and NOx prediction was studied in the gas turbine burner. Adding hydrogen to the fuel increased significantly turbulent burning velocity and OH distribution in the domain. The effect of hydrogen on the central stagnation point was studied and the simulation results did not show a significant effect on the stagnation point location.

    Beside the flame shape, this study showed that although the CFD NOx prediction tools in ANSYS CFX and ANSYS FLUENT predict the trend of NOx and the flame propagation in the right manner, in order to use as a reliable prediction tool in the gas turbine industry they need to be improved. 

  • 45.
    Chieh-Yi, Kuo
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Fabrication and Optical Properties of ZnO Nanocrystal/GaN Quantum Well Based Hybrid Structures2012Independent thesis Advanced level (degree of Master (Two Years)), 80 credits / 120 HE creditsStudent thesis
    Abstract [en]

    Optical properties of hybrid structures based on zinc oxide nanocrystals (NCs) and Gallium Nitride quantum well (QW) has been studied. The ZnO NCs thin films on the top of GaN QW structures were fabricated using spin coating. The surface morphology was characterized by scanning electron microscopy (SEM). We have performed temperature dependence time-resolved photoluminescence (TRPL) measurements of the bare AlGaN/GaN QW structures and hybrids, containing ZnO NCs. It was found that at some temperatures the QW PL decay has shorter decay time in the presence of ZnO NCs thin film compared to the bare QW. The effect was stronger for the samples with thinner cap layers. The results are discussed in terms of three models such as exciton nonradiative energy transfer (NRET), tunneling effect, and piezoelectric field influence on the QW exciton energy.

  • 46.
    Gasparini, Isabella
    Linköping University, Department of Physics, Chemistry and Biology, Biology. Linköping University, The Institute of Technology.
    Cardiorespiratory responses upon increased metabolism in the Ornate Tinamou, Nothoprocta ornata2012Independent thesis Advanced level (degree of Master (Two Years)), 40 credits / 60 HE creditsStudent thesis
    Abstract [en]

    The Bolivian Ornate Tinamou, Nothoprocta ornata, lives higher than 3300 m above sea level and must constantly deal with a restricted availability of atmospheric oxygen, i.e., chronic hypoxia. Interestingly enough, the Ornate Tinamou has a small heart to body ratio, which implies a reduced ability in transporting oxygenated blood to the tissues. In order to increase knowledge about the cardiorespiratory response of the Ornate Tinamou, heart rate (HR) and ventilation frequency (VR) were monitored during resting at 25 °C. The values were compared with those obtained in conditions known to elevate metabolism, i.e., lowered temperature and graded exercise. This was later compared with domestic chickens, Gallus gallus. Results showed a significant increase in HR at 4 °C, 305 ±42 bpm in the Ornate Tinamou when compared with HR at 25°C, 241± 48 bpm (330 ±42bpm and 239 ±32bpm in chicken). A significant increase in VR was only observed in chicken. As expected, with a progressive increase in running speed, a significant increase in HR in both species was observed. At 1,5 km h-1, HR in the Ornate Tinamou was 327 ±5,6 bpm and 342 ±8,5 in chicken. At 3,0 km h -1 HR was 383 ±15 bpm and 404 ±7,9, respectively. However, HR was not significantly higher in the Ornate Tinamou than in chicken, indicating that there must be other physiological adaptations involved in the sufficient oxygen delivery to tissues, e.g. a high blood oxygen affinity or a preference for anaerobic metabolism due to living in a chronic hypoxic environment.

  • 47.
    Diószegi, Attila
    et al.
    Department of Mechanical Engineering and Industrial Organisation / Component Technology, Jönköping University, Jönköping.
    Svensson, Ingvar L
    Department of Mechanical Engineering and Industrial Organisation / Component Technology, Jönköping University, Jönköping.
    A comparison of Fourier vs. Newtonian thermal analyse and its influence on the inverse kinetic growth calculationManuscript (preprint) (Other academic)
    Abstract [en]

    Thermal analysis of cooling curves is a metallurgical process control tool. Any phase transformations and their kinetics are reflected in the cooling rate. An interpretation of the cooling rate and temperatures is coupled to critical parameters, which are needed to assure correct quality of the melt and to give recommendations to modify the melt. This paper was inspired by the question, how well does a thermal ana lysis with one or two thermocouples and subsequent numerical analysis reflect the real phase transformations which occur?

    Inverse kinetic analysis using Fourier Thermal Analysis and Newtonian Thermal Analysis has been investigated using simulated cooling curves. The present study uses a direct simulation including a kinetic model for simulation of a eutectic phase. In this case, since the solidification sequence is well defined the inverse kinetic analysis should recreate the relation between the growth rate and supercooling of the eutectic phase. The Newtonian Thermal Analysis is based on an interpretation of a single thermal point with respect to solidification and contains a series of assumptions which are not entirely undoubted physically.

    Consequently the inverse kinetic analysis results in random quality growth parameters. The Fourier Thermal Analysis is based on interpretation of temperature differences between two thermal points with respect to solidification. The calculations conducted, in combination with the inverse kinetic analysis reveal a stable procedure. The decisive parameter determining the quality of inverse analysis is the distance between the thermal points analysed. Closely situated thermal points assure the best quality. The Fourier Thermal Analysis reflects the solidification most correctly.

  • 48.
    Ektarawong, Annop
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Growth and characterization of graphene on 4H-SiC(0001)2012Independent thesis Advanced level (degree of Master (Two Years)), 80 credits / 120 HE creditsStudent thesis
    Abstract [en]

    Thermal annealing 4H-SiC(0001) substrates to produce epitaxial graphene on Si-terminated SiC was performed using five different procedures, i.e. direct and indirect current heating at different based pressures and a temperature of about 1300 . The aim is to study the effects of graphene growth under different conditions and also to produce large homogeneous graphene. To investigate the prepared samples, two surface analytical techniques, i.e. low energy electron microscopy (LEEM) and photoelectron spectroscopy (PES) have been used. LEEM was first used to observe the surface morphologies of the prepared samples. In combination with LEEM instrument, low energy electron diffraction (LEED) was used to verify the existence of graphene on SiC substrate. The number of graphene layer was determined by collecting electron reflectivity at different electron energies. The number of dips observed in the electron reflectivity curve corresponds to the number of graphene layer.

    The experimental results obtained from LEEM and LEED have demonstrated that a film consisting of fairly large domains of 1 and 2 monolayer (ML) graphene was obtained by direct current heating of SiC under high vacuum (HV) condition with the based pressure of 10-6 Torr. A domain size in the range of up to about 5 to 10 μm have been observed. Meanwhile another graphene film prepared by the same method and the same temperature but under ultra high vacuum (UHV) condition with the based pressure of 10-10 Torr has much smaller domain size of 1 ML graphene compared to that grown under HV condition. We therefore suggested that the based pressure during the graphene growth has a strong influence on the morphology of graphene. This is because the Si evaporation rate is suppressed when heated in a high pressure environment, which normally leads to the improvement of the surface quality. The suppression of the Si evaporation rate has also been verified by a result obtained from the other sample directly heated under much higher based pressure, i.e. in an argon (Ar) environment of 1 atm.

    In addition to LEEM and LEED, the existence of graphene on SiC substrate has also been verified by the PES measurement. The C1s spectrum of graphene sample grown on SiC(0001) substrate showed three components, i.e. bulk SiC, graphene (G) and the buffer layer (B) located at 283.7 eV, 284.5 eV and 285.1 eV, respectively. The intensity ratios of the three components in the C1s spectrum were also used to estimate the number of graphene layer. The estimated number of graphene layer corresponds to the result obtained from LEEM.

  • 49.
    Nangunoori, Chetan Kumar
    et al.
    Linköping University, Department of Management and Engineering, Fluid and Mechatronic Systems. Linköping University, The Institute of Technology.
    Kumar Bhaskar, Ravichandra Kumar
    Linköping University, Department of Management and Engineering, Fluid and Mechatronic Systems. Linköping University, The Institute of Technology.
    Parametric Ram Air Channel Model for Flow Optimization2012Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Ram air channel or NACA channel is used to direct the ambient air for various purposes in an aircraft, such as pressurizing the cabin or as a coolant to heat exchangers and even more other applications like a cooling of the coolant. It is designed; such that it supplies the required amount of ambient air for various operations as mentioned, even aero-dynamical features should be taken into consideration while designing.

    In past, the developed prototypes are to be designed first and then experimented to optimize the design which gives accurate predictions and makes easy to understand the phenomenon occurring. These methods can lead to lot of waste in resources and time, in order to avoid these, some new mathematical methods have been implemented before finalizing the prototype which might save resources, time and minimize the possibility of having wrong outcomes. Some additional steps are included during calculation stage prior to the prototype stage; they are the computer aided simulations. These simulations can be as accurate as real time simulations and can bring closer to accuracy rate which is a needed prior to prototype stage.

    The aim is to design a tool chain for a Ram air channel which in turn is used to optimize the flow, then supplied to heat exchangers for cooling the hot refrigerant from the avionics systems. The requirements of the heat exchanger are decided on the applications it is used and the range of temperature to be cooled.

    In this study work, firstly estimate the size of the heat exchanger for the required performance, followed by the geometry of Ram air channel designing in CAD application so that it maintains the required amount of mass flow rate for the performance of heat exchanger. Finally these both components are implemented in simulation loop to iterate the designs of NACA channel in order to get the final model to optimize the flow for a heat exchanger.

     

  • 50.
    Sahlberg, Jörgen
    Swedish Meteorological and Hydrological Institute, Norrköping, Sweden.
    A Hydrodynamical Model for Calculating the Vertical Temperature Profile in Lakes During Cooling1983In: Nordic Hydrology, ISSN 0029-1277, E-ISSN 1996-9694, Vol. 14, no 4, 239-254 p.Article in journal (Refereed)
    Abstract [en]

    A one-dimensional hydrodynamical model is used for simulating the vertical temperature profile in a lake during cooling conditions. The vertical mixing rate is calculated by solving the equations for turbulent kinetic energy, k, and dissipation of energy, ε. The heat exchange between the water and atmosphere consists of the radiation fluxes, sensible and latent heat flux. Temperature measurements from Lake Väsman during November-December, 1981, were used in the verification study. The agreement between calculated and measured temperature profiles is very good. This indicates that both the mixing processes and the net heat flux are well described in the model.

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