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  • 1.
    Svensson, Marlene
    Linköping University, Department of Management and Engineering.
    A CFD Investigation of a Generic Bump and its Application to a Diverterless Supersonic Inlet2008Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    This is a Master Thesis done at the Swedish Defence Research Agency with the purpose to design and investigate how different geometries of a compression surface integrated with an intake affects the performance such as distortion, boundary layer diversion, pressure recovery and deceleration of speed.

    The work was divided in two parts. In the first part, CFD calculations using the FOI developed Edge 4.1 code were made for the compression surfaces alone. In the second part the most promising design was integrated with an intake. Two more bumps with the intake were modelled and the three geometries were compared to the intake without bump. Surface flow, deceleration of Mach number, pressure recovery, mass flow, boundary layer diversion, lift and drag were the factors chosen to be examined, boundary layer diversion and pressure recovery being the two most vital.

  • 2.
    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.  

  • 3.
    Ledin, Staffan
    Linköping University, Department of Electrical Engineering, Integrated Circuits and Systems.
    A Comparison of Radix-2 Square Root Algorithms Using Digit Recurrence2015Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    When designing an electronic system, it might be desirable to implement a custom square root calculator unit to ensure quick calculations. The different questions when it comes to square root units are many. What algorithms are there? How are these algorithms implemented? What are the benefits and disadvantages of the different implementations? The goal of this thesis work is to try to answer these questions. In this paper, several different methods of calculating the radix-2 square root by digit recurrence are studied, designed and compared. The three main algorithms that are studied are the restoring square root algorithm, the non-restoring square root algorithm and the SRT (Sweeney, Robertson, Tocher) square root algorithm. They are all designed using the same technology and identical components where applicable. This is done in order to ensure that the comparisons give a fair assessment of the viability of the different algorithms. It is shown that the restoring and non-restoring square root algorithms perform similarly when using 65 nm technology, a 16 bit input, full data rate and 1.2 V power supply. The restoring square root algorithm have a slight edge when the systems are not pipelined, while the non-restoring algorithm performs slightly better when the systems are fully pipelined. The SRT square root algorithm perform worse than the other two in all cases.

  • 4.
    Sjöström, Oskar
    Linköping University, Department of Computer and Information Science, Software and Systems.
    Parallelizing the Edge application for GPU-based systems using the SkePU skeleton programming library2015Independent thesis Advanced level (degree of Master (Two Years)), 300 HE creditsStudent thesis
  • 5.
    Ödling, Mattias
    Linköping University, Department of Management and Engineering, Environmental Technology and Management. Linköping University, Faculty of Science & Engineering.
    How Provider Value is Perceived in regards to Integrated Product Service Offerings and why: A case study2015Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    As companies grow larger and become more international, it is likely that it comes to a point where it would be cheaper to produce on site, or at least have distribution centers, rather than having a centralized production that requires long range shipping. As this occurs, there is a wide range of challenges that the company must face, however these challenges are by now well documented and while not to be underestimated and called “easy” it is nothing new as a wide range of companies have done it before. One aspect that however is less known is the influence that external differences has, in other words factors that would produce a differing result even with the exact same internal setup, on the perceived aspects (referred to as Values in this work) from the providers point of view. In particular what is interesting is the perceived positive impacts above expectations that is gained from having external differences. To be able to better understand and quantify this impact the term “Provider Value” has been created and is being researched towards understanding what Values exist and how they are being affected.Provider Value (PV) is a cutting edge concept within eco-design research that this work is based on and in particular ProVa – Provider Value Evaluation for Integrated Product Service Offerings (Matschewsky et al. 2015) is the latest step to date towards creating the tools needed to increase the utilization, and reap the benefits, of PVs. Another interesting and relevant aspect to PV is how Product/Service System (PSS) could be an essential part in paving a new way of avoiding increased environmental impact while having economic growth. This is done by adding services on top of already existing products (Sakao et al. 2009).To find out more about what kind of external factors that might be behind the differences a case study was conducted, interviewing employees at two companies within one concern in Sweden and Japan. The results of this work indicates that if the company want its PVs to remain the same the main obstacle is external economic differences. In this particular study it is also clear that differences in business model and company structure has a big impact. With all the discussion regarding environment it was on a surprisingly low level of interest at both companies and what mattered was that the products cleared the minimum requirements, nothing more, as “any additional return is hard to estimate”. If PV keeps growing and tools are made to assist, this could not only help simplify the transitioning to other countries and help utilizing existing Values from the start, it could also increase the utilization in general, in particularly in regards to the Environment.

  • 6.
    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.

  • 7.
    Imani, Roghayeh
    et al.
    Univ Ljubljana, Fac Elect Engn, SI-1000 Ljubljana, Slovenia; [ 2 ] Univ Ljubljana, Fac Hlth Sci, SI-1000 Ljubljana, Slovenia .
    Pazoki, M
    Uppsala Univ, Angstrom Lab, Dept Chem, S-75120 Uppsala, Sweden.
    Boschloo, G ()
    Uppsala Univ, Angstrom Lab, Dept Chem, S-75120 Uppsala, Sweden.
    Turner, Anthony (Contributor)
    Linköping University, Department of Physics, Chemistry and Biology, Biosensors and Bioelectronics. Linköping University, Faculty of Science & Engineering.
    Kralj-Iglič, V (Contributor)
    Univ Ljubljana, Fac Hlth Sci, SI-1000 Ljubljana, Slovenia.
    Iglič, Ales
    Univ Ljubljana, Fac Elect Engn, SI-1000 Ljubljana, Slovenia.
    Band edge engineering of TiO2@DNA nanohybrids and implications for capacitive energy storage devices.2015In: Nanoscale, ISSN 2040-3364, E-ISSN 2040-3372, Vol. 7, no 23, 10438-10448 p.Article in journal (Refereed)
    Abstract [en]

     Novel mesoporous TiO2@DNA nanohybrid electrodes, combining covalently encoded DNA with mesoporous TiO2 microbeads using dopamine as linker, were prepared and characterised for application in supercapacitors. Detailed information about donor density, charge transfer resistance and chemical capacitance, which have important role in the performance of an electrochemical device, were studied by electrochemical methods. The results indicated the improvement of electrochemical performance of TiO2 nanohybrid electrode by DNA surface functionalisation. A supercapacitor was constructed from TiO2@DNA nanohybrids with PBS as electrolyte. From the supercapacitor experiment, it was found that the addition of DNA played an important role in improving the specific capacitance (Cs) of the TiO2 supercapacitor. The highest Cs value of 8 F/g was observed for TiO2@DNA nanohybrids. The nanohybrid electrodes were shown to be stable over long-term cycling, retaining 95% of their initial specific capacitance after 1500 cycles.

  • 8.
    Haider, Daniyal
    Linköping University, Department of Electrical Engineering, Integrated Circuits and Systems. Linköping University, Faculty of Science & Engineering.
    On-Chip Phase Measurement Design Study in 65nm CMOS Technology2015Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Jitter is generally defined as a time deviation of the clock waveform from its desired position. The deviation which occurs can be on the leading or lagging side and it can be bounded (deterministic) or unbounded (random). Jitter is a critical specification in the digital system design. There are various techniques to measure the jitter. The straightforward approach is based on spectrum analyzer or oscilloscope measurements. In this thesis an on-chip jitter measurement technique is investigated and the respective circuit is designed using 65 nm CMOS technology. The work presents the high level model and transistor level model, both implemented using Cadence software. Based on the Vernier concept the circuit is composed of an edge detector, two oscillators, and a phase detector followed by a binary counter, which provides the measurement result. The designed circuit attains resolution of 10ps and can operate in the range of 100 - 500 MHz Compared to other measurement techniques this design features low power consumption and low chip area overhead that is essential for built-in self-test (BIST) applications.

  • 9.
    Prasad Rao Pasupuleti, Krishna
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, The Institute of Technology.
    Investigation and Study of Crosstalk2015Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Crosstalk is defined as an unwanted coupling between the conductors. By this it is meant that signals from one of the signal conductors (a generator in this case) are coupled to another signal conductor (receptor), or conductors (receptors), depending on the number of conductors in the vicinity of the generator. Crosstalk in this way affects the signal level on the receptor and thereby affects the total system performance within the system. This can happen in several ways, one of which is through edge coupling. Edge coupling is a process where two signal conductors are placed beside each other in the same layer while the ground conductor could have been placed either under these conductors, in a separate layer like Mclin (Microstrip coupled lines) and Sclin (Coupled striplines), or beside the signal conductors as in Cpwcpl2 (Coplanar wave guide coupled lines). This then means that edge coupling occurs through the sides where the generator and the receptor are facing each other. Broadside coupling is another way, where it occurs when the signal conductors are broadside faced to each other in different layers with reference planes above and below these signal conductors. Coupling of the signals from the generator to the receptor can occur through capacitive coupling or inductive coupling. Capacitive coupling, also known as electrical coupling, occurs due to the difference in the characteristic impedance of the generator (usually 50 or 100 §Ù) and its heavy load (1 k§Ù or more) which results in high voltage difference between the generator and the reference conductor (ground). This leads to the creation of a charge across the generator and the receptor-facing sides and finally results in the electric field coupling between them. On the other hand, inductive coupling, also known as magnetic coupling, occurs when the load is less than the characteristic impedance of the generator, and this thereby results in a heavy current flow through the generator which in return results in a strong magnetic field around itself and so leads to magnetic coupling to the receptor. The aim in this thesis is to measure both the capacitive and inductive coupling load¡¯s impacts on both the edge coupling and the broadside coupling models through crosstalk on the receptor. This thesis starts with the background and corresponding theory and equations to the crosstalk coupling. Later on it tests both the edge- and broadside coupling models with different physical properties exploitation. Inductive and capacitive loads are used to measure the resulting crosstalk coupling. Particularly to see the effect of capacitive and inductive coupling in reality in multi layered PCB, a Sbclin (Broadside coupled striplines) model has been used with different angular placement of the generator. Finally mclin physical models are compared with the simulated models and corresponding differences are discussed. It can be concluded that crosstalk effect increases or decreases with physical properties exploitation. Crosstalk also increases with the wrong termination of the load.

  • 10.
    Ekström, Anneli
    et al.
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Mattsson, Ida
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Från singelmedia till multimedia, En studie om förutsättningarna för ett mediehanteringssystem2005Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Teknomedia is a development company for new medias within the NT group. Teknomedia produce product and company presentations, commercials and web solutions among many things. They have also developed Edge, a publishing tool for easy publishing of web pages.

    During year 2005, NT will start a local TV channel as a complement to the morning paper and the web. It is calculated to be in full operation year 2009. The idea is to develop Edge so it not only will act publishing tool for the web but also for TV and with time for other channels such as radio and paper.

    This report describes how Edge II should look like and function for the TV channel. The torrent from recording to transmission and storing is analyzed and solutions for a fast news torrent are introduced. Equipment and formats are discussed and metadata for the different formats presented. The result should not be seen as a general publishing system for a TV station but an adaptation to NT:s needs and resources. The report describes how Edge II to a great extent automates and simplifies the torrent for all involved in the TV production and gives them the possibility to rapidly spread news to the public.

  • 11.
    Gustafsson, Fredrik
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Designing the edge beams2010Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    New construction of bridges is the choice of edge beams something that is often discussed. In Sweden currently three different models for the edge beams. When edge beams be elected, all the pros and cons of the different types of edge beams should be considered before deciding on the type of edge beam to be used. Many believe that decisions concerning the selection of edge beams sometimes not correct. This is based in the fact that there are many opinions about what edge beam which should be used. The choice of edge beam controls how advanced dewatering and railing design will be. Edge beam design has a major impact on drainage and bridge railing design. The choice of the edge beam can both simplify the de-watering and provide a better profitability.

    The purpose of this work is to investigate the problems there are with today's three standard edge beams. The work also aims to provide suggestions for improvement through new designs of edge beam to meet good dewatering properties, and good profitability.

    Interviews with different people are a great foundation for the work to get a broad perspective over the problem of edge beams. Current bridge snake TK Bro has been a good source in describing the edge beams and the dewatering takes place.

    Edge Beams in Sweden has been used for a long time without any significant change has occurred. My study shows that there is a demand for the development of the edge beams and find new solutions to achieve profitability. This report describes my suggestion for improvement. The improvements are based on the problems as set forth and the rules that exist in TK Bro.

  • 12.
    Haglund, Johanna
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Heatloss through a concrete slab - a comparison of edge beams2010Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Of all the heat that is supplied in an average house in Sweden, about 15% of the heat leaks out through the foundation and the ground. A foundations task is to provide a solid base for a house while it should also keep the heat in the house. This report deals with the foundation concrete slab, where the focus is largely on comparing three different types of edge beams with respect to thermal bridges and energy consumption. This work has been performed in collaboration with Fiskarhedenvillan which is one of the largest house suppliers in Sweden. Fiskarhedenvillan are constantly working with reducing the energy consumption in their houses and now wish to obtain a better insight into how the choice of edge elements in the slab can affect this. To get a better understanding of how heat transfer works the report begins with a theoretical part. It deals with how heat conduction, radiation and convection works. The theoretical part also deals with foundations, thermal bridges, concrete slab and edge beams in general. The edge beam solutions mentioned in the report are:

    • U‐min grund, energy‐efficient

    • Leca edge element

    • Dorocell, L‐element

    Using the computer program HEAT2, a simulation of the edge beams has been made to obtain different values of thermal bridges. These values were then used to calculate how the choices of the edge beams affect the total energy consumption in a house

  • 13.
    Waqar, Azeem
    et al.
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Zafar, Muhammad Ammar
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Simulation and Optimization of Frequency Reuse in OFDMA Networks2011Independent thesis Advanced level (degree of Master (One Year)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Efficient radio resource management is an important aspect when it comes to achieving high bit rates in technologies such as the 3GPP Long Term Evolution (LTE). This thesis aims at understanding existing frequency reuse schemes in OFDMA networks, and to develop an algorithm for frequency allocation for irregular cellular layouts. Previous work done in this field mostly covers schemes for regular cells, whereas in real life cellular layouts are mostly irregular. A comparison of the existing allocation schemes for the users near the boundary of the cells, also known as edge users, with our scheme is presented.

    Reuse-1, Fractional frequency reuse-3 with random frequency allocation (FFR3-RFA) (for edge users) and our algorithmic frequency allocation (FFR3-AFA) scheme are simulated and compared. FFR3-AFA algorithm assigns a frequency sub-band to a cell by considering the frequency allocations in the neighbor cell edges and the overlap area between those neighboring cells. Static simulations were performed with one user per base station and constant downlink traffic of 100 Kbits/sec, so that all the resources are utilized and there is maximum interference. This way, the difference between the frequency reuse schemes is much more evident. The throughput for our calculation is the ratio of the total successful packets sent in the network and the total packets sent in the network. Small scenarios are considered with different downlink data rates and the results show that FFR3-AFA has better performance than the other two techniques. There is also room for improvement in the algorithm by introducing other factors into the equation other than overlap area, such as user throughput.

  • 14.
    Sandberg, Pontus
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Mobile Broadband Service Experience and Evaluation2007Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    EGDE manages Internet Radio streams up to 96kbit/s while WCDMA R99 delivers satisfactory quality for media streams up to 320 kbit/s. Internet Radio isnot possible to use over GPRS with satisfactory quality. The quality assessment for Internet Radio is highly dependent on the stream bit rate and a stream of 128 kbit/s delivers high user satisfaction.

    For online gaming other parameters than the well known latency, jitter and packet loss aects the session quality. High start up or map load times will cause premature game termination and poor quality grading. Shorter Counter- Strike sessions are playable over HSPA where it outperforms WCMDA R99 inboth network performance and user quality assessment. World of Warcraft has more limited network requirements and is playable over both WCDMA R99 and

    HSPA but suers from latency impairments when played over GPRS/EDGE. The developed objective quality prediction model for First Person Shooter (FPS) games, like CounterStrike, shows pretty good performance, despite a small number of test persons. The model predicts online gaming quality with an RMSE value of 0.609, prediction accuracy of 91.9% and correlation between predicted and subjective MOS of 0.8803.

  • 15.
    Milton, Ida
    Linköping University, Department of Physics, Chemistry and Biology, Biology. Linköping University, The Institute of Technology.
    Enclosure utilization and space preference in captive dholes (Cuon alpinus)2013Independent thesis Basic level (degree of Bachelor), 10,5 credits / 16 HE creditsStudent thesis
    Abstract [en]

    Knowledge of how animals utilize their space can be important when they are held in captivity. This is especially true for animals that are on the edge of extinction as such knowledge can possibly help to improve their captive breeding programs. One of these animals is the dhole, Cuon alpinus. The aim for this study was to assess how the dholes at Kolmården zoo utilize their space, if they share space and if they prefer to use specific pathways. The study took place at Kolmården zoo during 12 days and included a total of 72 hours of visual observation. A summarized map, with subdivision into 14 zones, of the dholes’ enclosure was used when recording the dholes’ location. For location recordings scan sampling was used. The dholes showed marked differences in utilization of zones ranging from the most popular zone with 1341 markings to the least popular zone with 71 markings. There was a clear preference for three zones during the whole observation period. No marked differences for utilization of zones were found between feeding vs. non-feeding days and morning vs. afternoon. Furthermore, the dholes showed a tendency for sharing space and utilization of two pathways. This project makes it evident that the dholes at Kolmården zoo prefer certain zones within their enclosure. This is probably due to that the zones preferred provides locations with access to resting, lookout possibilities etc that is important for the dholes to express a natural behavior.

  • 16.
    Abdul Aziz Hasan Ali, Aamir
    et al.
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, The Institute of Technology.
    Shahzad, Muhammad Adil
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, The Institute of Technology.
    A Joint Subcarrier/Power allocation Scheme for OFDMA-based Cellular Networks2012Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The assignment of this master thesis consists of initiating power, subcarrier allocation in a dynamic FFR based scheme designed for multi-cell OFDMA networks and to enhance the throughput of all center users in bandwidth hungry borrower cells (overloaded cells) which was previously degraded by original FFR3 scheme as a result of partitioning of system bandwidth into center and edge bands respectively. The method uses band borrowing to compensate center user’s throughput loss in a semi and fully overloaded system. The scheme uses dynamic programming method (0/1 knapsack problem) to bargain an edge band on various power levels and tends to check the best combination (power and sub-carrier) which the system can utilize while still maintaining acceptable throughput loss for the users at the edge of the neighboring cell (lender cell).

    The algorithm consists of generating a borrowing request to neighboring cells for utilizing their edge bands by the overloaded borrower cell if their average center user throughput reaches below a minimum threshold value set in the system. The borrowing method uses 0/1 knapsack problem to capture an edge band based on limiting factors of total cost in average throughput losses by neighbors (Ci) and Un (tolerable mean user edge user throughput loss by lending cell). While solving knapsack problem the lender (neighbors) will check Ci and Un before granting the right to use its edge band. The later stage requires reducing subcarrier power level in order to utilize the lenders edge band using "soft borrower" mode. The borrowed sub-carriers will be activated take power from the original center band sub-carriers of the overloaded cell by taking into account the interference between the lender and the borrower. In case of negative (0) reply from the lender cell after the first request, multiple requests are generated at reduce power level at every step to order to acquire more bands. If a neighbor has band borrowing requests from multiple overloaded base stations, the band will be granted to the one which gives minimal loss in terms of throughput to the lender cell.

    The simulation results are analyzed w.r.t reuse-1 and FFR3 scheme of a multi cell regular and irregular scenarios comprising of lightly to heavily overloaded cells with various subcarrier allocation patterns. An overhead and time assessment is also presented between borrower and lender cells. Simulation results show an increase of 60% in center user’s throughput w.r.t original FFR3 scheme with an acceptable loss of 18% at the edges in complex overloaded scenarios while the overall system throughout increases by 35%.

  • 17.
    Cervin, Albert
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, The Institute of Technology.
    Adaptive Hardware-accelerated Terrain Tessellation2012Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    In this master thesis report, a scheme for adaptive hardware terrain tessellation is presented. The scheme uses an offline processing approach where a height map is analyzed in terms of curvature and the result is stored in a resource called density map. This density map is then bound as a resource to the hardware tessellation stage and used to bias the tessellation factor for a given edge. The scheme is implemented inside FrostbiteTM2 by EATM DICETM and produces good results while making the heightfield rendering more efficient. The performance gain can be used to increase the rendering detail, allowing for better visual appearance for the terrain mesh. The scheme is currently implemented for hardware tessellation but could also be used for software terrain mesh generation. The implementation works satisfactory and produces good results with a reasonable speed.

  • 18.
    Dzeko, Jasmin
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, The Institute of Technology.
    Scheduling of Norrköping Airport2012Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    For Securitas AB case to maintain their position in Norrkoping Airport is it important to effectives their staffing and schedules. This is required to achieve cost reductions which will in turn give them the competitive edge to maintain their position at the annual contracts concluded between the municipality and the airport. To effectives their staffing and schedules are theoretical parts going to be used to control their groups and business better. The theoretical parts are in the form of scheduling principles.

    At the streamlining of operations is an optimization model going to be used that has several features that enable a comprehensive optimization solution to embarrass the most costeffective staffing for the schedule planning. A technical system as an information system will also be used to structure Securitas work more efficiently with a better accounting of the employees and to facilitate the implementation of a standardized approach. The importance of standardized work is treated much in the LEAN philosophy and is considered important in this case to obtain the theoretical aspects and the information system to work together smoothly. A scheduling policy that is recommended that Securitas uses is the Perceptual Control Theory as it has proven to be successful by companies that applied it.

    The solution to Securitas Problem is a combination of theory and quantitative methods that can be used to count on. Optimization model and information system will together with the scheduling principles create better conditions for Securitas to set up a new optimal schedule to reduce costs by 10 % and increase the efficiency for Securitas operations in the airport. These actions are going to lead to higher profitability and will result that Securitas wins the annual procurements in Norrkoping Airport.

  • 19.
    Velpanur, Shashank
    Linköping University, Department of Management and Engineering, Quality Technology and Management. Linköping University, The Institute of Technology.
    Development of methods and tools for monitoring and analyzing customer data2013Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The market in today’s world is dominated by customers and their requirements. Customer feedback is essential for manufacturing companies trying to establish a foothold in the service environment. New product development is often recognized as the trump card held by most manufacturing companies that allow them to gain a competitive edge over their rivals in the market. Utilizing customer’s feedback in new product  development is a step that many companies are taking to be able to satisfy customer needs and requirements which enables the companies to firstly, retain the customers and secondly, bring in new business. Interviewing customers for feedback is a very common method employed by service companies to be able to capture and store data which is then analyzed to identify any patterns emerging i.e. any particular features preferred, any features disliked, etc. This thesis uses interviews as a method to be able to capture feedback from the customers which can then be utilized in new product development.

    The basis of this thesis is formed by developing a method for analyzing and monitoring customer data. The customer perceives a product or a service based on his/ her experience in using it and hence forms an opinion on it. This thesis mainly focuses on interacting with internal operators (Volvo CE employees who participated in a previous measurement) to understand and collect their feedback of the product, the L220F wheel loader, as an example to develop the method, due to the fact that “real” customers are not as easy to reach and interview. The data collected will then be compared to logged data of the product usage by these operators. Finding a correlation between the answers to the interviews and the measured data will help identify the gaps in how the wheel loader is used by operators of different skill levels and how it can be used. If successful, this method can then be utilized on external customers of Volvo CE and also on other products manufactured by Volvo CE.

    The conclusions drawn from this thesis are that while all customers must be equally considered while taking feedback, whether they are professionals or rookies, Volvo CE should rate their answers differently while designing a new product to meet customer requirements. Also, what could be seen from the clustering is that more heterogeneous groupings of operators are formed wherein no one cluster is made up of purely one class of operators.

  • 20.
    Dzeko, Jasmin
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Schemaläggning av Norrköping Airport2012Independent thesis Basic level (degree of Bachelor), 10,5 credits / 16 HE creditsStudent thesis
    Abstract [en]

    For Securitas AB case to maintain their position in Norrkoping Airport is it important to effectives their staffing and schedules. This is required to achieve cost reductions which will in turn give them the competitive edge to maintain their position at the annual contracts concluded between the municipality and the airport. To effectives their staffing and schedules are theoretical parts going to be used to control their groups and business better. The theoretical parts are in the form of scheduling principles.

    At the streamlining of operations is an optimization model going to be used that has several features that enable a comprehensive optimization solution to embarrass the most cost-effective staffing for the schedule planning. A technical system as an information system will also be used to structure Securitas work more efficiently with a better accounting of the employees and to facilitate the implementation of a standardized approach. The importance of standardized work is treated much in the LEAN philosophy and is considered important in this case to obtain the theoretical aspects and the information system to work together smoothly. A scheduling policy that is recommended that Securitas uses is the Perceptual Control Theory as it has proven to be successful by companies that applied it.

    The solution to Securitas Problem is a combination of theory and quantitative methods that can be used to count on. Optimization model and information system will together with the scheduling principles create better conditions for Securitas to set up a new optimal schedule to reduce costs by 10 % and increase the efficiency for Securitas operations in the airport. These actions are going to lead to higher profitability and will result that Securitas wins the annual procurements in Norrkoping Airport.

  • 21.
    Leiviskä, Emily
    Linköping University, Department of Computer and Information Science. Linköping University, The Institute of Technology.
    Implicit Channel Allocation in GSM/EDGE radio networks2012Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Efficient channel allocation in GSM communication is difficult and believed to be a performance bottleneck. This thesis is dedicated to studying the performance of GSM/EDGE networks in modern usage scenarios (surfing the web, chatting and streaming services) under the assumption that explicit channel allocation is not needed.

    Users are able to be (re-)allocated at any time without explicit signaling and the typically associated delay. The radio hardware of these users is identical to that of typically used devices and the theoretical peak performance is not affected. This allows the network to use the radio channels in a more efficiently way and the delays from signaling are reduced or eliminated.

    The thesis studies this problem by statistically modeling such usage scenarios and the resulting channel utilization patterns. The study finds that the latency can be reduced by 40-70% for typical radio hardware, and that network throughput can be improved by up to 20%. However, further studies are needed on the subject.

  • 22.
    Bergner, Adam
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    Studier av habitatval och revirstrukturer hos vassångare (Locustella luscinioides) i Tåkern2012Independent thesis Basic level (degree of Bachelor), 10,5 credits / 16 HE creditsStudent thesis
    Abstract [en]

    The Savi’s Warbler (Locustella luscinioides) is a recently established bird species in a few reedy shallow lakes of southern Sweden and has only been found nesting for the last twenty years. Little is known about the species' habitat preferences, breeding biology and demands for specific territory structures at breeding sites in Sweden. Knowledge of a newly established species’ habitat requirements is essential to maintain a viable population and design action plans. This study, the first of its kind in Sweden, examined the vegetation structures in occupied territories of Savi’s Warblers at Lake Tåkern, the country's stronghold for the species. The species was found to be associated with the outer edge zones and fragmented areas of reed (Phragmites australis). Occupied territories differed from randomly chosen unoccupied (control) territories by having a thicker layer of reed litter, and on average more bushes of Willow (Salix spp.) present. Reed density and reed height did not differ from areas that lacked Savi’s Warblers. Territorial and displaying males were concentrated in two edge areas with a mosaic of reed islets where the territories remained relatively close together.

  • 23.
    Vallgren, Emma
    et al.
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, The Institute of Technology.
    Bolling Landtblom, Elsa
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, The Institute of Technology.
    Att synas i butikshyllan -  En fallstudie om varumärkesexponering i butikshyllan för Brunneby Musteri och deras konkurrenter2012Independent thesis Basic level (degree of Bachelor), 10,5 credits / 16 HE creditsStudent thesis
    Abstract [en]

    This report aims to examine how Brunneby Musteri is to update the brand attention for Brunneby Musteri at retail stores. Brunneby wish to assure their brand will catch the customers’ eye in the store and therefore get assistance to discover what to improve. The family business Brunneby Musteri (Brunneby) was founded in 1941 and is located nearby Göta Kanal in the county of Östergötland. Brunneby produce products such as lemonade, jam, jelly, marmelade, cider and vinegar. The company core values are Natural, Healthy and Tasty, although quality and tradition are central values for Brunneby aswell.

    The methods used are interviews and observations. The results given from the methods are analysed from theories within the subject. Brunneby has many good qualities as a company and a food producer, although this report focus on marketing and graphic design, which is an area of weakness for Brunneby. The given conclusions are as follows; Brunneby has an inconsistent graphic manual, neither do they have a distinct target group for each product. Brunneby uses marketing via digital newsletters, their web page and, to some extent, different events. For those customers who are not familiar with Brunneby, the packaging design is the main channel of marketing.

    One noticed dilemma in the stores is the transportation package that in some stores are placed on the shelves to expose the products, although the edge of the package is covering the product etiquettes. The transportation package is in the current situation undesigned and does not communicate the brand. To minimize the risk of being unnoticed, Brunneby is recommended to design the package to become eye catching and communicate the brand.

    The conclusion shows that Brunneby should perform a customer analysis to discover the target group and the customer associations of the brand. Brunneby should then adjust their brand identity to the customer associations. Brunneby is advised to enhance the relationship between the customer and the brand. This will be accomplished by activating the customer through campaigns, contests or product tastings that enable the customer to create brand associations and initiates a relationship to the brand.

  • 24.
    Kabir, MD
    et al.
    Linköping University, Department of Management and Engineering, Business Administration.
    Plantis, Jerome
    Linköping University, Department of Management and Engineering, Business Administration.
    The Influence of Firm's Human Resource andMarket Demand on a Firm's Innovation Strategy2012Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Background: In technology based industries, firms which originate from advanced economies have traditionally occupied the leading position. In order to keep that position, they relied on strong efforts devoted to research and development, striving for being at the cutting edge of technology. During the last decade, we observed that some change happened amongst the top ranking of firms within the telecommunication industry with the apparition of Huawei, which originates from China, an emerging economy, in second position.

    Aim: This research is aimed to investigate the influence of firm’s human resource and market demand on firm’s innovation strategy.

    Definitions: Human resource represents the employees working for a company. In our study, when we mention human resource we deal with employees working in research and development. Market demand refers to the products which are demanded on a specific market. For our research we divided it in three categories: less advanced, advanced and most advanced products. Innovation strategy deals with the way a firm organizes its research and development in order to innovate according to either, in our research, new-tofirm or new-to-world innovation strategy.

    Completion and results: This study revealed that Huawei managed to adjust its innovation strategy in accordance with its human resources and market demand. Thanks to an efficient and adapted innovation strategy, Huawei now manages to perform better than its main competitor Ericsson, not only on developing or emerging markets, but also in advanced markets. We also observed the role of rules and regulations and cooperation, without which Huawei would not have been able to lead an efficient new-to-firm strategy. We created a model which is designed to give a better understanding of the situation and illustrate the interrelation between human resource, market demand, innovation strategy and performance.

  • 25.
    Sajid, Muhammad
    et al.
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, The Institute of Technology.
    Siddiqui, Imran
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, The Institute of Technology.
    A distributed, load-aware, power and frequency bargaining protocol for LTE-based networks2012Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    In this thesis a distributed, dynamic, load aware, joint power and frequency allocation protocol for 4G networks along with system-level simulated results are presented. In all cellular networks, a key limiting factor for throughput is inter-cell interference, especially at the cell edges. Several methods have been proposed and adopted in each mobile network generation to cancel or suppress its effects, whereas each method has its drawbacks in terms of receiver complexity or additional control nodes. However, the proposed protocol presented here does not impose any architectural changes.  In 4G networks such as LTE, the choice of OFDMA for the air interface has paved the way for selective frequency and power allocation in the available spectrum. Taking advantage of this opportunity, fractional frequency reuse (FFR) has been proposed in OFDMA based mobile networks in order to reduce the throughput loss at the cell edges due to inter-cell interference. In FFR, center users lose part of available spectrum that is dedicated to the edge users.  Our protocol aims to minimize this loss of center users incurred by FFR, at the cost of minimal degradation at the edges.

    An eNodeB, only when overloaded, requests its neighbours’ edge band to be used for its center users at a reduced power level. This is done via small message exchange between the eNodeBs. The neighbors of the overloaded eNodeBs solve a small local knapsack problem to decide whether band lending is feasible or not. A distinguishing feature of this protocol is the power level adjustment for the borrowed band, which is mutually decided by the borrower and lender. The band is released when it is not needed or it is causing unacceptable loss to the lender. The implementation is done in a Matlab based LTE system level simulator. For the implementation of our protocol in the simulator, starting point was implementation of FFR-3 functionality, a prerequisite and a baseline for comparison with our protocol.

    Results are compared among three different setups of re-use1, FFR-3 and our protocol by varying number of overloaded eNodeBs for various numbers of scenarios and the comparison is made based on the center users’ throughput, edge users’ throughput. An estimation of time and protocol overhead is also presented. We have observed center users’ throughput gain up to 46%, at the cost of 9% edge users’ throughput loss, when compared to the classic FFR-3 scheme. The overall system throughput goes up to 26 % in heavily loaded scenario.

     

    The utility of the protocol for an LTE system is evident from the results, which is supported by the dynamic and decentralized nature of the protocol. This ensures better utilization of spectrum, by temporarily allocating more bandwidth where it is needed more.

  • 26.
    Samini, Ali
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Large scale audience interaction with a Kinect sensor2012Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    We present investigation and designing of a system that interacts with big audience, sitting in a dimmed theater environment. The goal is to automatically detect audiences and some of their actions. Test results indicate that because of low light condition we can’t rely on RGB camera footage in a dimmed environment. We use Microsoft Kinect Sensor to collect data from environment. Kinect is designed to be used with Microsoft Xbox 360 for gaming purposes. It has both RGB and Infrared depth camera. Change in amount of visible light doesn’t affect data from depth camera. Kinect is not a strong camera so it has limitations that we should deal with. Viewing angles of both cameras and depth range of Infrared camera are limited. Viewing angles of depth camera are 43° vertical and 57° horizontal. Most accurate range of depth camera is 1 meter to 4 meters from camera. Non-infrared reflective surfaces cause gaps in depth data. We evaluate possibility of using Kinect camera in a large environment with big audience. “Dome 3D theater” in Norrkoping Visualization Center C, is selected as environment to investigate and test the system. We ran some tests to find the best place and best height for camera to have most coverage. Our system works with optimized image processing algorithms that use 3D depth data instead of regular RGB or Grayscale image. We use “libfreenect”, Open Kinect library to get Kinect sensor up and running. C++ and OpenGL are used as programing languages and graphics interface, respectively. Open GLUT (OpenGL Utility Toolkit) is used for system’s user interface. It was not possible to use Dome environment for every test during the programming period so we recorded some depth footage and used for later tests. While evaluating the possibility of using Kinect in Dome environment, we realized that implementing a voting system would make a good demonstration and test application. Our system counts votes after audiences raise their hands to vote for something.

  • 27.
    Skachkova, Katsiaryna
    Linköping University, Department of Management and Engineering, Business Administration.
    Voluntary turnover among technical consultants. Mediating role of social identities and perceived promises2012Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Background: Development of technologies and high pace of changes made a modern organization highly dependent on the expertise and assistance of technology specialists. To be able to compete and be cost efficient, but at the same time be on the cutting-edge of technology development, is an essential requirement for doing business in the contemporary world. Moreover, this requirement became a solid ground for the emergence of a technical consulting industry and a new type of human resources - technical consultants. On the one hand, technical consultants are the main resources of technical consulting organizations, but on the other hand, technical consultants can cause harm to technical consulting organization, particularly, in the case of voluntary turnover.

    Aim: Through the qualitative analysis of the four technical consultants’ voluntary turnover stories in Sweden and based on the literature review, this master thesis opens up the door to the world of technical consultants. The aim of this work is to seek new insights into the problem of voluntary turnover in a new context of technical consultants and discover what role multiple identities and perceived promises play in voluntary turnover decision.

    Results: Technical consultants are a type of knowledge workers with non-traditional work arrangements. Empirical evidence demonstrates that technical consultants’ decision to quit can be described using "Eight motivational forces", but the framework should be extended, due to developing multiple identities and receiving perceived promises from multiple sources.

  • 28.
    Fransson, Thomas
    Linköping University, Department of Physics, Chemistry and Biology.
    X-ray absorption spectroscopy by means of Lanczos-chain driven damped coupled cluster response theory2011Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    A novel method by which to calculate the near edge X-rayabsorption fine structure region of the X-ray absorption spectrum has been derived and implemented. By means of damped coupled cluster theory at coupled cluster levels CCS, CC2, CCSD and CCSDR(3), the spectra of neon and methane have been investigated. Using methods incorprating double excitations, the important relaxation effects maybe taken into account by simultaneous excitation of the core electron and relaxation of other electrons. An asymmetric Lanczos-chain driven approach has been utilized as a means to partially resolve the excitation space given by the coupled cluster Jacobian. The K-edge of the systems have been considered, and relativistic effects are estimated with use of the Douglas--Kroll scalar relativistic Hamiltonian. Comparisons have been made to results obtained with the four-component static-exchange approach and ionization potentials obtained by the {Delta}SCF-method.

    The appropriate basis sets by which to describe the core and excited states have been been determined.  The addition of core-polarizing functions and diffuse or Rydberg functions is important for this description. Scalar relativistic effects accounts for an increase in excitation energies due to the contraction of the 1s-orbital, and this increase is seen to be 0.88 eV for neon. The coupled cluster hierachy shows a trend of convergence towards the experimental spectrum, with an 1s -> 3p excitation energy for neon of an accuracy of 0.40 eV at a relativistic CCSDR(3) level of theory. Results obtained at the damped coupled cluster and STEX levels of theory, respectively, are seen to be in agreement, with a mere relative energy shift.

  • 29.
    Josefsson, Mattias
    Linköping University, Department of Electrical Engineering, Computer Vision. Linköping University, The Institute of Technology.
    3D camera with built-in velocity measurement2011Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    In today's industry 3D cameras are often used to inspect products. The camera produces both a 3D model and an intensity image by capturing a series of profiles of the object using laser triangulation. In many of these setups a physical encoder is attached to, for example, the conveyor belt that the product is travelling on. The encoder is used to get an accurate reading of the speed that the product has when it passes through the laser. Without this, the output image from the camera can be distorted due to a variation in velocity.

    In this master thesis a method for integrating the functionality of this physical encoder into the software of the camera is proposed. The object is scanned together with a pattern, with the help of this pattern the object can be restored to its original proportions.

  • 30.
    Salim, Ahmed
    Linköping University, Department of Electrical Engineering, Electronics System.
    Evaluation of Word Length Effects on Multistandard Soft Decision Viterbi Decoding2011Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    There have been proposals of many parity inducing techniques like Forward ErrorCorrection (FEC) which try to cope the problem of channel induced errors to alarge extent if not completely eradicate. The convolutional codes have been widelyidentified to be very efficient among the known channel coding techniques. Theprocess of decoding the convolutionally encoded data stream at the receiving nodecan be quite complex, time consuming and memory inefficient.This thesis outlines the implementation of multistandard soft decision viterbidecoder and word length effects on it. Classic Viterbi algorithm and its variantsoft decision viterbi algorithm, Zero-tail termination and Tail-Biting terminationfor the trellis are discussed. For the final implementation in C language, the "Zero-Tail Termination" approach with soft decision Viterbi decoding is adopted. Thismemory efficient implementation approach is flexible for any code rate and anyconstraint length.The results obtained are compared with MATLAB reference decoder. Simulationresults have been provided which show the performance of the decoderand reveal the interesting trade-off of finite word length with system performance.Such investigation can be very beneficial for the hardware design of communicationsystems. This is of high interest for Viterbi algorithm as convolutional codes havebeen selected in several famous standards like WiMAX, EDGE, IEEE 802.11a,GPRS, WCDMA, GSM, CDMA 2000 and 3GPP-LTE.

  • 31.
    Magnusson, Emelie
    Linköping University, Department of Management and Engineering, Mechanics.
    FE analysis and design of the mechanical connection in an osseointegrated prosthesis system2011Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    In this master thesis the connection between the two major parts of an osseointegrated prosthesis system for lower limb amputees has been investigated by finite element (FE) analysis. The prosthesis system is developed by Integrum and the current design consists of a fixture, which is integrated in the residual bone, an abutment that penetrates the skin and an abutment screw that holds the parts together. The connection between the fixture and the abutment has a hexagonal section and a press-fit section that together form the connection. Due to wear and fracture problems it is desired to improve the connection. A tapered connection could be an alternative and three different taper angles, the effect of the length of the taper and the smoothness of the outer edge of a tapered fixture have been investigated. The results show that the taper has potential to function well and that a longer connection will give lower stresses in the system, but further investigations are needed.

  • 32.
    Salomonsson, Stefan
    Linköping University, Department of Electrical Engineering, Information Coding.
    Simulation of Temperature Distribution in IR Camera Chip2011Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The thesis investigates the temperature distribution in the chip of an infrared camera caused by its read out integrated circuit. The heat from the read out circuits can cause distortions to the thermal image. Knowing the temperature gradient caused by internal heating, it will later be possible to correct the image by implementing algorithms subtracting temperature contribution from the read out integrated circuit.

    The simulated temperature distribution shows a temperature gradient along the edges of the matrix of active bolometers. There are also three hot spots at both the left and right edge of the matrix, caused by heat from the chip temperaturesensors and I/O pads. Heat from the chip temperature sensors also causes an uneven temperature profile in the column of reference pixels, possibly causing imperfections in the image at the levels of the sensors.

    Simulations of bolometer row biasing are carried out to get information about how biasing affects temperatures in neighbouring rows. The simulations show some row-to-row interference, but the thermal model suffers from having biasing heat inserted directly onto the top surface of the chip, as opposed to having heat originate from the bolometers. To get better simulation results describing the row biasing, a thermal model of the bolometers needs to be included.

    The results indicate a very small temperature increase in the active pixel array, with temperatures not exceeding ten millikelvin. Through comparisons with another similar simulation of the chip, there is reason to believe the simulated temperature increase is a bit low. The other simulation cannot be used to draw any conclusions about the distribution of temperature.

  • 33.
    Zhang, Liang
    Linköping University, Department of Electrical Engineering, Automatic Control.
    Network Capacity, Coverage Estimation and Frequency Planning of 3GPP Long Term Evolution2010Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The recent increase of mobile data usage and emergence of new applications such as Online Gaming, mobile TV, Web 2.0, Streaming Contents have greatly motivated the 3rd Generation Partnership Project (3GPP) to work on the Long Term Evolution (LTE). The LTE is the latest standard in the mobile network technology tree. It inherits and develops the GSM/EDGE and UMTS/HSPA network technologies and is a step toward the 4th generation (4G) of radio technologies designed to optimize the capacity and speed of 3G mobile communication networks. In this thesis, the LTE system capacity and coverage are investigated and a model is proposed on the base of the Release 8 of 3GPP LTE standards. After that, the frequency planning of LTE is also studied. The results cover the interference limited coverage calculation, the traffic capacity calculation and radio frequency assignment. The implementation is achieved on the WRAP software platform for the LTE Radio Planning.

  • 34.
    Kamalian, Rafayel
    Linköping University, Department of Mathematics. Linköping University. Linköping University, The Institute of Technology.
    On a number of vertices with an interval spectrum in proper edge colorings of some graphs2011Report (Other academic)
    Abstract [en]

    A proper edge t-coloring of a graph G is a coloring of edges of G with colors 1,2,...,t such that each edge receives one color, each color is used at least for one edge, and no two adjacent edges receive the same color. The set of colors of edges incident with a vertex x of G is called a spectrum of x.

    A proper edge t-coloring of a graph G is interval for a vertex x of G if the spectrum of x is an interval of integers. A proper edge t-coloring of a graph G is persistent-interval for a vertex x of G if the spectrum of x is an interval of integers with 1 as it's least element.

     

    For graphs G from some classes of graphs, we obtain estimates for the possible number of vertices for which a proper edge t-coloring of G can be interval or persistent-interval.

  • 35.
    Kamalian, Rafayel
    Linköping University, Department of Mathematics. Linköping University, The Institute of Technology.
    On a number of colors in cyclically interval edgecolorings of trees2010Report (Other academic)
    Abstract [en]

    A proper edge t-coloring of a graph G is a coloring of edges of G with colors 1,2,...,t such that each edge receives one color and no two adjacent edges receive the same color. A proper edge t-coloring of  G is called  a cyclically interval t-coloring if 1) at least one edge is colored k, for each k=1,2,...,t., and 2) for each vertex v of G the colors of edges incident with v are consecutive modulo t.We find, for an arbitrary tree G, all possible values of t  for which G admits a cyclically interval  t-coloring.

  • 36.
    große Osterhues, Dirk
    Linköping University, Department of Management and Engineering, Economic Information Systems.
    The Strategic Value of ICT for Swedish Business Leadership2010Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Information and communication technology already has a long history of influence in basically all areas of an enterprise. In recent years though, a major discussion emerged whether information and communication technologies (ICT) offer an additional strategic value for a business.

    The different positions maintain reasonable arguments on both sides. One position is that ICT basically has become a commodity, obtainable by everyone. There would be no strategical nor competitive gain, so extra efforts in ICT would be in vain. Another position is that, although, nowadays ICT is easy to acquire, the organisational skills necessary to manage the change and to profit from a good system are a scarce resource and difficult to reproduce.

    As much as this discussion has been the subject of many academic articles, as little has the research on the views of practitioners emerged. What is their opinion on the strategic relevance of information and communication technology? Do they consider it as merely a necessary commodity, only used to stay competitive, or do they think that there is a competitive advantage to gain in a sophisticated and possibly leading-edge system? Also, a third view is conceivable, in which practitioners regard ICT as just a tool, which serves best by reconsidering the intensity of its use in every new venture.

    In order to get answers to these questions, semi-structured telephone interviews with leading ICT officers were conducted. The outcome gives a broad overview on what practitioners consider as strategically important in ICT systems and what the current view of the academic guild on this question looks like. An analysis on where, how and why the academic- and the business-views overlap or differ from each other, together with an interpretation of the interview results, concludes the work.

  • 37.
    Gunnarsson, Linus
    et al.
    Linköping University, Department of Management and Engineering, Assembly technology .
    Bitar, Nadim
    Linköping University, Department of Management and Engineering, Assembly technology .
    Assembly Analysis - Fixed Leading Edge for Airbus A3202010Independent thesis Basic level (university diploma), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    The objective with this thesis project was to with the simulations software Delmia make a working build philosophy for the new concept of the fixed leading edge for the Airbus A320 airliner, but also to make two conceptual fixtures in the modular framework BoxJoint for pre-drilling of two sub assemblies.

     

    Everything started with a study in Delmia to both recap on previous knowledge and to learn more about it. This was followed by early simulations on the new concepts that were provided by project partners. Then a study was made in the Affordable Reconfigurable tooling, ART-concept. A suggested build philosophy was created and possible areas for automation were identified. These areas were all the drilling and fettling operations except the drilling in the last stage where the pre-drilled holes are opened up. More investigations needs to be done to see if a robot can install and remove slave pins that are used in the last stage. Two conceptual designs on fixtures were created where one uses two industrial robots with vision systems to get the correct accuracy when drilling the product. The other was build to be able to use a Tau-Gantry robot solution together with a vision system.

  • 38.
    Roth, Stefan
    Linköping University, Department of Electrical Engineering, Communication Systems.
    Frame Allocation and Scheduling for Relay Networks in the LTE Advanced Standard2010Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The use of relays is seen as a promising way to extend cell coverage and increase rates in LTE Advanced networks. Instead of increasing the number of base stations (BS), relays with lower cost could provide similar gains. A relay will have a wireless link to the closest BS as only connection to the core network and will cover areas close to the cell edge or other areas with limited rates.

    Performing transmissions in several hops (BS-relay & relay-user) requires more radio resources than using direct transmission. This thesis studies how the available radio resources should be allocated between relays and users in order to maximize throughput and/or fairness. Time and frequency multiplexed backhaul is investigated under a full buffer traffic assumption. It is shown that the system will be backhaul limited and that the two ways of multiplexing will perform equally when maximising throughput and/or fairness. The analysis results in a set of throughput/fairness suboptimal solutions, dependant on how many relays are used per cell. The results are verified by simulations, which also show the limiting effects on throughput caused by interference between relays.

    It is also analysed how the resource allocation should be done given non-fullbuffer traffic. A resource allocation that minimises packet delay given a certain number of relays per cell is presented. The analysis is based on queuing theory.

    Finally some different schedulers and their suitability for relay networks are discussed. Simulation results are shown, comparing the throughput and fairness of Round Robin, Weighted Round Robin, Proportional Fairness and Weighted Proportional Fairness schemes. It is shown that allocating the resource among the relays according to the number of users served by the relays improves the fairness.

  • 39.
    Johansson, Mattias
    et al.
    Linköping University, Department of Electrical Engineering.
    Ehrs, Jonas
    Linköping University, Department of Electrical Engineering.
    Low-Power Low-Noise IQ Modulator Designs in 90nm CMOS for GSM/EDGE/WCDMA/LTE2010Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The current consumption of the IQ modulator is a significant part of the totalcurrent consumption of a mobile transmitter platform and reducing it is of greatinterest. Also, as the WCDMA/LTE standards specifies full duplex transmissionsand Tx and Rx are most often using the same antenna, it is crucial to have asolution with low noise generation. Two new proposals have been studied with theaim to reduce the current consumption and noise contribution of the IQ modulator.

    A current mode envelope tracking IQM is the first of the studied designs. Thisimplementation lowers the bias currents in the circuit in relation to the amplitudeof the baseband input signals, meaning that a low input amplitude results in alowering of the current consumption. It proves to be very efficient for basebandsignals with a high peak-to-average ratio. Simulations and calculations have shownthat an average current reduction of 56 % can be achieved for an arbitrary LTEbaseband signal.

    The second is an entirely new passive mixer design where the baseband voltagesare sequentially copied to the RF node, removing the need for V-to-I conversion inthe mixer which reduces current consumption and noise. Results from simulationshas proven that this design is fully capable of improving both current consumptionas well as the noise levels. With an output power of 4.0 dBm, the power consumptionwas 43.3 mW, including clock generating circuits. This, combined with thefact that the design is small and simple, means that there is definitely a possibilityto replace the present IQM design with a passive mixer.

  • 40.
    Ahlman, Per-Arne
    Linköping University, Department of Mechanical Engineering, Machine Design.
    Smörjning Av Lager2009Independent thesis Basic level (university diploma), 15 credits / 22,5 HE creditsStudent thesis
    Abstract [en]

    The work thesis was performed at Assalub a company which is situated in Åtvidaberg. The company works with developing, manufacturing and marketing equipment for handling of lubricants for light and heavier industry. The work thesis it is based on a inquiry Assalub got from MacGregor which is a company within cargo solution, from port to offshore system.

    For unloading grain and other material from the ship cargo it is used combined inlet feeder and screw conveyor, there the inlet feeder is drilling down through the cargo and feed the screw conveyer with material to further destination. At the bottom of the screw conveyer and the inlet feeder there is a bearing that keep the parts together. However the lubrication of the bearing must be made manually. Until now the bearing was lubricated manually through a grease nipple from the bottom of the drill once a day.

     

    The purpose of the thesis was the construction of a lubricating system namely a pump with a grease container which should be placed inside the space of the screw conveyer, so the bearing will be continually lubricated and able to work several days without any stoppage.

    After receiving drawings and operating data for the screw conveyer, the details for the construction was designed in CAD system Solid Edge. The solid mechanics calculations on the weakest point on the construction was made by hand and afterwards the drawings for respectively details was made.

    The construction was completed, but because of the time limit for this work thesis, the manufacturing, mounting and testing were not included in these weeks. The grease containers capacity is approximately seventy-two hours, although desirable should be up to seven days. According to the solid mechanics calculations, the construction should have no problem to resist the stresses it would be exposed to.

    Since this is a prototype there is probably some adjustments and improvements to do, but the estimating is that the system should work properly as it is now.

  • 41.
    Zheng, W.T.
    et al.
    Department of Materials Science and National Key Laboratory of Superhard Materials, Jilin University, Changchun 130023, China, Department of Precision Engineering, Chiba Institute of Technology, 2-17-1 Tsudanuma, Narashino 275-0016, Japan, Department of Physics, Linkoping University, S-581 83 Linkoping, Sweden, National Key Laboratory of Materials Surface Modification by Laser, Ion, and Electron, Dalian University of Technology, Dalian 116024, China.
    Guo, J.H.
    Department of Physics, Uppsala University, Box 530, 751 21 Uppsala, Sweden.
    Sakamoto, Y.
    Department of Precision Engineering, Chiba Institute of Technology, 2-17-1 Tsudanuma, Narashino 275-0016, Japan.
    Takaya, M.
    Department of Precision Engineering, Chiba Institute of Technology, 2-17-1 Tsudanuma, Narashino 275-0016, Japan.
    Li, X.T.
    Department of Materials Science and National Key Laboratory of Superhard Materials, Jilin University, Changchun 130023, China.
    Chao, P.J.
    Department of Materials Science and National Key Laboratory of Superhard Materials, Jilin University, Changchun 130023, China.
    Jin, Z.S.
    Department of Materials Science and National Key Laboratory of Superhard Materials, Jilin University, Changchun 130023, China.
    Xing, K.Z.
    Department of Physics, Linkoping University, S-581 83 Linkoping, Sweden.
    Sundgren, J.-E.
    Department of Physics, Linkoping University, S-581 83 Linkoping, Sweden.
    Chemical bonding in carbon nitride films studied by X-ray spectroscopies2001In: Diamond and related materials, ISSN 0925-9635, Vol. 10, no 9-10, 1897-1900 p.Article in journal (Refereed)
    Abstract [en]

    Carbon nitride films are deposited using dc magnetron sputtering in a N2 discharge. The nature of chemical bonding of the films is investigated using X-ray photoelectron spectroscopy, near-edge X-ray absorption fine structure, and X-ray emission spectroscopy. X-Ray photoelectron spectroscopy spectra show that N1s binding states depend on substrate temperature, in which two pronounced peaks can be observed. The near edge X-ray absorption fine structure at C1s and N1s exhibits a similar absorption profile in the p* resonance region, but the s* resonance is sharper in the N1s spectra. Resonant N K-emission spectra show a strong dependence on excitation photo energies. Compared XPS N1s spectra with recent theoretical calculations by Johansson and Stafstrom, two main nitrogen sites are assigned in which N bound to sp3 hybridized C and sp2 hybridized C, respectively. The correlation of X-ray photoelectron, X-ray absorption, and X-ray emission spectra for N in carbon nitride films is also discussed. © 2001 Elsevier Science B.V. All rights reserved.

  • 42.
    Young, T.
    et al.
    Department of Mechanical Engineering, University of Limerick, Limerick, Ireland.
    Mahony, B.
    Department of Mechanical Engineering, University of Limerick, Limerick, Ireland.
    Humphreys, B.
    Aerospace Systems and Technology, Consett, Durham, United Kingdom.
    Totland, E.
    McClafferty, A.
    Department of Mechanical Engineering, University of Limerick, Limerick, Ireland.
    Corish, J.
    Department of Mechanical Engineering, University of Limerick, Limerick, Ireland.
    Durability of hybrid laminar flow control (HLFC) surfaces2003In: Aerospace Science and Technology, ISSN 1270-9638, Vol. 7, no 3, 181-190 p.Article in journal (Refereed)
    Abstract [en]

    As a part of the European Commission sponsored HYLTEC (Hybrid Laminar Flow Technology) project, a SAAB 2000 aircraft - fitted with a number of small laser drilled panels on the wing leading edge - completed 20 months of routine service, the objective being to investigate contamination and durability aspects of Hybrid Laminar Flow Control (HLFC) suction surfaces. A post-flight test investigation of these panels, manufactured from Nd-YAG laser drilled titanium, aluminium and carbon fibre polyetheretherketone (PEEK) composite, has been conducted. Using Scanning Electron Microscopy (SEM), evidence of corrosion and damage was investigated. An optical inspection technique was used to measure hole geometries and the results were compared to pressure loss measurements through the panels. Titanium was found to be the most robust material, displaying no adverse affect from this exposure, whilst aluminium was found to be substantially less durable. The PEEK carbon fibre composite showed signs of surface degradation after only two months of flight trials. © 2003 Éditions scientifiques et médicales Elsevier SAS. All rights reserved.

  • 43.
    Godlewski, M.
    et al.
    Institute of Physics, Polish Academy of Sciences, Al. Lotnikow 32/46, 02-668 Warsaw, Poland.
    Goldys, E.M.
    Semiconductor Science and Technology Laboratory, Macquarie University, Sydney, NSW, Australia.
    Pozina, G.
    Department of Physics and Measurement Technology, Linkoping University, Linkoping, Sweden.
    Monemar, B.
    Department of Physics and Measurement Technology, Linkoping University, Linkoping, Sweden.
    Pakula, K.
    Institute of Experimental Physics, Warsaw University, Warsaw, Poland.
    Baranowski, J.M.
    Institute of Experimental Physics, Warsaw University, Warsaw, Poland.
    Prystawko, P.
    High Pressure Research Center (Unipress), Polish Academy of Sciences, Warsaw, Poland.
    Leszczynski, M.
    High Pressure Research Center (Unipress), Polish Academy of Sciences, Warsaw, Poland.
    In-plane and in-depth nonuniformities in defect distribution in GaN and InGaN epilayers2001In: Physica. B, Condensed matter, ISSN 0921-4526, Vol. 308-310, 102-105 p.Article in journal (Refereed)
    Abstract [en]

    The in-plane and in-depth characteristics of the GaN and InGaN epilayers grown by the metalorganic chemical vapour deposition (MOCVD) on three different substrates (sapphire, SiC and bulk GaN) are evaluated. Relatively large intensity fluctuations of "edge" GaN and InGaN emissions are observed and are related to the details of the micro-structure of the GaN and InGaN films studied. The experiments indicate a nonuniform defect distribution in all types of the MOCVD films studied. In particular, the decoration of structural defects with impurities, an increased defect accumulation at the interfaces and a surprisingly small influence of the micro-structure on the in-plane homogeneity of the yellow band cathodoluminescence emission are observed. © 2001 Elsevier Science B.V. All rights reserved.

  • 44. Onipko, A.
    et al.
    Malysheva, L.
    Bogolyubov Inst. for Theor. Physics, 252143, Kiev, Ukraine.
    Triple-, double-, and fractionally-spaced Wannier-Stark ladders2001In: Solid State Communications, ISSN 0038-1098, Vol. 118, no 2, 63-67 p.Article in journal (Refereed)
    Abstract [en]

    The concept of Wannier-Stark (WS) quantization literally refers to infinite crystals or bulk electron states. In real finite crystals, the bulk and edge or surface states always coexist. Moreover, when the surface states are already considerably localized due to the presence of a constant electric field, the WS ladder (WSL) and hence the WS localization may not yet come into play, at least, in the canonical form of WS quantization Ej = const±je, j = 0, 1, 2, ... (Ej is the one-electron energy, and the parameter e is associated with the electric field strength). We show that at certain voltages Vm, m = 3, 4, ..., which are lower than V8 needed for the WS band opening (the sub-WS regime), the mid-spectrum levels can form triple-, double-, and fractional-spaced WSLs, where El = ±l[1+2/(m-2)]em. It is also found that in the WS regime, the quantization of surface localized states (sls) smoothly changes from the Airy type (at the spectrum edges) to the WS type with a pronounced energy interval in between, where the level spacing doubles that of canonical WSL. Possible experimental manifestations of predicted effects are also outlined.

  • 45.
    Zheng, W.T.
    et al.
    Department of Materials Science, Jilin University, Changchun 130023, China, State Key Laboratory of Superhard Materials, Jilin University, Changchun 130023, China, National Key Laboratory of Ion, Electron, Laser Modification, Da Lian Science and Technology University, Dalian 116024, China.
    Yu, W.X.
    Department of Materials Science, Jilin University, Changchun 130023, China.
    Li, H.B.
    Department of Materials Science, Jilin University, Changchun 130023, China.
    Wang, Y.M.
    Department of Materials Science, Jilin University, Changchun 130023, China.
    Cao, P.J.
    State Key Laboratory of Superhard Materials, Jilin University, Changchun 130023, China.
    Jin, Z.S.
    State Key Laboratory of Superhard Materials, Jilin University, Changchun 130023, China.
    Broitman, E.
    Department of Physics, Linkoping University, S-581 83 Linkoping, Sweden.
    Sundgren, J.-E.
    Department of Physics, Linkoping University, S-581 83 Linkoping, Sweden.
    Chemical bonding, structure, and hardness of carbon nitride thin films2000In: Diamond and related materials, ISSN 0925-9635, Vol. 9, no 9-10, 1790-1794 p.Conference paper (Other academic)
    Abstract [en]

    Carbon nitride films are deposited on Si(001) substrates by reactive d.c. magnetron sputtering graphite in a pure N2 discharge. The chemical bonding and structure of carbon nitride films were probed using Fourier transformation infrared (FTIR) and near edge X-ray absorption fine structure (NEXAFS), and the hardness was evaluated using nanoindentation experiments. The structure and hardness for the films are dependent on the substrate temperature (T(s)). FTIR and NEXAFS spectra show that N atoms are bound to sp1, sp2 and sp3 hybridized C atoms, and the intensity of p(*) resonance for C1s NEXAFS spectra is the lowest for the film grown at T(s) = 350°C, having a turbostratic-like structure, high hardness and stress. The correlation between the structure and hardness of carbon nitride films is discussed. (C) 2000 Elsevier Science S.A. All rights reserved.Carbon nitride films are deposited on Si(001) substrates by reactive d.c. magnetron sputtering graphite in a pure N2 discharge. The chemical bonding and structure of carbon nitride films were probed using Fourier transformation infrared (FTIR) and near edge X-ray absorption fine structure (NEXAFS), and the hardness was evaluated using nanoindentation experiments. The structure and hardness for the films are dependent on the substrate temperature (Ts). FTIR and NEXAFS spectra show that N atoms are bound to sp1, sp2 and sp3 hybridized C atoms, and the intensity of p* resonance for C1s NEXAFS spectra is the lowest for the film grown at Ts = 350°C, having a turbostratic-like structure, high hardness and stress. The correlation between the structure and hardness of carbon nitride films is discussed.

  • 46.
    Ozturk, M.
    et al.
    Trondheim Biological Station, Norwegian Univ. of Sci. and Technol., Bynesvagen 46, N-7018 Trondheim, N..
    Croot, P.L.
    Department of Chemistry, Analytical and Marine Chemistry, Goteborg Univ., SE-412 96 G..
    Bertilsson, S.
    Linköping University, The Tema Institute, Department of Water and Environmental Studies. Linköping University, Faculty of Arts and Sciences.
    Abrahamsson, K.
    Dept. of Chemistry and Bioscience, Chalmers University of Technology, SE-412 96 Göteborg, Sweden.
    Karlson, B.
    Botanical Institute, Göteborg University, Box 461, SE-405 30 Goteborg, Sweden.
    David, R.
    CSIR, PO Box 17001, Congella 4013, Kwa-Zulu Natal, S. A..
    Fransson, A.
    Department of Chemistry, Analytical and Marine Chemistry, Goteborg Univ., SE-412 96 G..
    Sakshaug, E.
    Trondheim Biological Station, Norwegian Univ. of Sci. and Technol., Bynesvagen 46, N-7018 Trondheim, N..
    Iron enrichment and photoreduction of iron under UV and PAR in the presence of hydroxycarboxylic acid: Implications for phytoplankton growth in the Southern Ocean2004In: Deep-sea research. Part II, Topical studies in oceanography, ISSN 0967-0645, Vol. 51, no 22-24, 2841-2856 p.Article in journal (Refereed)
    Abstract [en]

    Iron(III) photoreduction and the responses of phytoplankton under ultraviolet (UV) and photosynthetically available radiation (PAR) were investigated with the presence of hydroxycarboxylic acid (glucaric acid (GA), a model compound for organic acids excreted by phytoplankton). The incubation experiments were carried out on board using seawater samples collected in the location of the winter ice edge (WIE) and the spring ice edge (SIE) of the Southern Ocean. In this paper, we focus on the results of experiment in WIE. Throughout the experiments, dissolved Fe(II), major nutrients and in vivo fluorescence were monitored regularly. In addition, Chl-a, POC/PON, cell densities of phytoplankton and bacteria, bacterial production, organic peroxide, hydrogen peroxide and total CO2 were measured. The results from the WIE show that iron enrichment had a substantial effect on phytoplankton growth rate. Fe(III) addition in the presence of GA (FeGA) gave higher Fe(II) concentration and higher growth rate of phytoplankton than those in controls. Our results suggest that hydroxycarboxylic acid had a significant chemical and biological impact. The presence of GA influenced iron photochemistry and iron availability to phytoplankton. Phytoplankton growth responses to iron enrichments in incubations under UV and PAR were completely dissimilar. It seems that FeGA addition prominently changes the harmful effect of UV on the phytoplankton population. This study provides preliminary information on how the photoreduction of iron(III) and the phytoplankton growth are affected by iron enrichment in the presence of hydroxycarboxylic acid. © 2004 Elsevier Ltd. All rights reserved.

  • 47.
    Bertilsson, S.
    et al.
    Linköping University, The Tema Institute, Department of Water and Environmental Studies. Linköping University, Faculty of Arts and Sciences.
    Carlsson, P.
    Department of Marine Sciences, Kalmar University, P. O. Box 905, SE-391 29 Kalmar, S..
    Graneli, W.
    Granéli, W., Department of Ecology/Limnology, Lund University, Ecol. Bldg., SE-223 62 Lund, Sweden.
    Influence of solar radiation on the availability of dissolved organic matter to bacteria in the Southern Ocean2004In: Deep-sea research. Part II, Topical studies in oceanography, ISSN 0967-0645, Vol. 51, no 22-24, 2557-2568 p.Article in journal (Refereed)
    Abstract [en]

    The influence of solar radiation on the ability of dissolved organic matter (DOM) to support bacterial growth, was studied in the eastern Atlantic sector of the Southern Ocean during the SWEDARP 1997/1998 cruise with SA Agulhas December 1997-February 1998. Vertical profiles of water samples (2-3000 m) were obtained from the Spring Ice Edge (SIE, 60°S, high chlorophyll-a) and from the Winter Ice Edge (WIE, 56°S, low chlorophyll-a) areas. Filter-sterilized water from each area and depth was incubated under natural solar radiation and in the dark for comparison. Photobleaching of humic substance fluorescence occurred in all studied water samples. The bleaching was typically larger in the initially more fluorescent deep waters, compared to the low-fluorescent surface waters. Both the irradiated water and the dark controls were re-inoculated with a mixed bacterial inoculum from the initially sampled water. Bacterial growth (accumulating cells) and bacterial production (protein synthesis) were monitored during a 16-19 day incubation of these cultures at near in situ temperature (2°C). Bacterial growth in cultures prepared from SIE water was largest at the surface (2-25 m), while the growth in corresponding cultures from the WIE did not vary much over depth. In contrast to the observed photobleaching, no clear effects of the irradiation on the ability of the DOM to support bacterial growth could be observed in either of the experiments. Hence, the degradation of fluorescent structures and other photochemical alterations of the organic matter did not have a major effect on the total pool of biodegradable organic substrates. The lack of effects of photoreactions on bacterial growth potential in the present study disagrees with the short-term bacterial growth response observed in other oceanic environments. This could be due to the different experimental approaches employed (short-vs. long-term incubations) or may indicate that the impact of photoreactions on bacterial growth in the Southern Ocean differ substantially from aquatic systems that are more influenced by terrestrial environments, as well as the warmer oligotrophic oceanic environments. © 2004 Elsevier Ltd. All rights reserved.

  • 48. Schifano, R.
    et al.
    Vinattieri, A.
    Department of Physics, University of Florence, Via Sansone 1, I-50019 Sesto Fiorentino, Italy.
    Bruzzi, M.
    Department of Energetics, Istituto Nazionale di Física Nucleare (INFN), University of Florence, Via di Santa Marta 3, I-50139 Florence, Italy.
    Miglio, S.
    Department of Energetics, Istituto Nazionale di Física Nucleare (INFN), University of Florence, Via di Santa Marta 3, I-50139 Florence, Italy.
    Lagomarsino, S.
    Department of Energetics, Istituto Nazionale di Física Nucleare (INFN), University of Florence, Via di Santa Marta 3, I-50139 Florence, Italy.
    Sciortino, S.
    Department of Energetics, Istituto Nazionale di Física Nucleare (INFN), University of Florence, Via di Santa Marta 3, I-50139 Florence, Italy.
    Nava, F.
    Department of Physics, University of Modena, Via Campi 213A, I-41100 Modena, Italy.
    Electrical and optical characterization of 4H-SiC diodes for particle detection2005In: Journal of Applied Physics, ISSN 0021-8979, Vol. 97, no 10, 103539- p.Article in journal (Refereed)
    Abstract [en]

    The electronic and optical properties of several (medium to high quality) 4H-SiC epitaxial sensors for particle detection have been studied. The samples are n -doped Schottky diodes with different nitrogen concentrations (6× 1013 cm-3 -5× 1015 cm-3) and thicknesses (20-40 µm). A full electrical and optical characterization has been performed by capacitance versus voltage measurements and near-band-edge low-temperature photoluminescence. The effective doping along the epilayer and the depletion width have been determined and data are consistent with the charge collection efficiency characterization performed with a minimum ionizing ? -source. All the investigated samples exhibit a 100% collection efficiency. In particular, the best samples yield a highly reproducible signal, well separated from the pedestal. Photoluminescence results show a linear relationship between the effective doping and the ratio of nitrogen-bound excitonic emission (Q0) and free excitonic line (I76), in agreement with a previous work on 4H-SiC with a higher doping concentration [I. G. Ivanov, C. Hallin, A. Henry, O. Kordina, and E. Janzn, J. Appl. Phys. 80, 3504 (1996)]. Moreover we show that the dependence of the major spectral features as a function of the penetration depth of the exciting laser beam can quantitatively provide information on substrate contribution to the photoluminescence. In conclusion, we bring evidence that a detailed characterization of SiC-based detectors, by all optical techniques, yields an accurate value for the net doping and gives a qualitative information on the epilayer thickness prior to any electrical wafer tests. © 2005 American Institute of Physics.

  • 49.
    Asratian, Armen
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Mathematics, Applied Mathematics.
    Casselgren, Carl Johan
    Some results on interval edge colorings of (a, B)-biregular bipartitie graphs2006Report (Other academic)
  • 50. Gil, B.
    et al.
    Bigenwald, P.
    Leroux, M.
    Paskov, Plamen
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Monemar, Bo
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Internal structure of the neutral donor-bound exciton complex in cubic zinc-blende and wurtzite semiconductors2007In: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 75, no 8Article in journal (Refereed)
    Abstract [en]

    We calculate the fine structure splitting of the near band edge donor-bound excitons in major cubic semiconductors using an approach inspired by an earlier one that consists in replacing the Morse potential by a Kratzer one, in order to account for the repulsion between the donor and the hole. A regular trend is observed when plotting the computed results in terms of donor binding energies for all these semiconductors. Second, we extend the method to wurtzite semiconductors, namely CdS, GaN, and ZnO. The previously reported trend is found again, but enriched with the strong anisotropy of the dispersion relations in the valence band of these semiconductors. We end up in addressing a quantitative interpretation of the fine structure splitting of the donor bound exciton complex which includes the jj coupling between the valence band Bloch and the envelope nonrigid rotator hole states. © 2007 The American Physical Society.

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