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  • 1.
    Larsson, John-Olov
    Linköping University, Department of Physics, Chemistry and Biology.
    Evaluation of Flux and Timing Calibration of the XMM-Newton EPIC-MOS Cameras in Timing Mode2008Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    XMM-Newton is a X-ray telescope launched december 1999, by the European Space Agency, ESA. On board XMM-Newton are two EPIC-MOS X-ray detectors. The detectors are build by Charged Coupled Devices (CCDs), of Metal Oxide Semi-conductor type. The EPIC-MOS cameras have four science operating modes. This project aims to evaluate the calibration for one of these four modes, the timing mode.

    The evaluation is divided into two parts. The first part is the evaluation of the flux calibration, performed by analysing various observation made in timing mode. The second part is the evaluation of timing properties by performing timing analysis of XMM-Newton observations of the Crab nebula compared to observations made in the radio wavelengths.

  • 2.
    Pettersson, Tobias
    Linköping University, Department of Electrical Engineering, Computer Engineering. Linköping University, The Institute of Technology.
    Synchronization of flywheel position between autonomous devices2012Independent thesis Advanced level (degree of Master (One Year)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    More computing power will be required in Scania’s future engine control units. Calculations is therefore needed to be performed on new hardware such as an FPGA. One problem that arises is synchronization of flywheelposition. This master thesis examines the opportunities existing Scania hardware has to perform synchronization of flywheel position. Different concepts for synchronization have been developed and compared with each other. One of the concepts have been implemented and made possible witha PCB-adapter. The results show that synchronization is possible within given real-time requirements. Finally, an analysis to series production has been made. It show the challenges that an FPGA will face when integrated into a future engine control unit.

  • 3.
    Vastesson, Alexander
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, The Institute of Technology.
    Micro-Structuring of New Materials Combined with Electronic Polymers for Interfaces with Cells2012Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

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

  • 4.
    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.  

  • 5.
    Hanson, Maryam
    Linköping University, Department of Electrical Engineering, Integrated Circuits and Systems.
    Study on Smart Dust Networks2016Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    This thesis work is done for the department of Electronic System at The Institute of Technology at Linköping University (Linköpings Tekniska Högskolan). Study's focus is to design and implement a protocol for smart dust networks to improve the energy consumption algorithm for this kind of network.

    Smart dust networks are in category of distributed sensor networks and power consumption is one of the key concerns for this type of network. This work shows that by focusing on improving the algorithmic behavior of power consumption in every network element (so called as mote), we can save a considerable amount of power for the whole network.

    Suggested algorithm is examined using Erlang for one mote object and the whole idea has put into test for a small network using SystemC.

  • 6.
    Holm, Rasmus
    Linköping University, Department of Computer and Information Science, Software and Systems.
    Energy-Efficient Mobile Communication with Cached Signal Maps2016Independent thesis Basic level (degree of Bachelor), 10,5 credits / 16 HE creditsStudent thesis
    Abstract [en]

    Data communication over cellular networks is expensive for the mobile device in terms of energy, especially when the received signal strength (RSS) is low. The mobile device needs to amplify its transmission power to compensate for noise leading to an increased energy consumption. This thesis focuses on developing a RSS map for the third generation cellular technology (3G) which can be stored locally at the mobile device, and can be used for avoiding expensive communication in low RSS areas.

    The proposed signal map is created by crowdsourced information collected from several mobile devices. An application is used to collect data in the mobile device of the user and the application periodically sends the information back to the server which computes the total signal map.

    The signal map is composed of three levels of information: RSS information, data rate tests and estimated energy levels. The energy level categorizes the energy consumption of an area into "High", "Medium" or "Low" based on the RSS, data rate test information and an energy model developed from physical power measurements. The coarse categorization provides an estimation of the energy consumption at each location. It is evaluated by collecting data traces on a smartphone at different locations and comparing the measured energy consumption at each location to the energy level categories of the map.

    The RSS prediction is preliminarily evaluated by collecting new data along a path and comparing how well it correlates to the signal map. The evaluation in this thesis shows that with the current collected data there are not enough observations in the map to properly estimate the RSS. However, we believe that with more observations a more accurate evaluation could be done.

  • 7.
    Pavski, Johann Joachim
    Linköping University, Department of Mathematics, Optimization . Linköping University, Faculty of Science & Engineering.
    Handover Optimization in GSM2015Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    In telecommunications in general and in GSM in particular, the handover is a feature that guarantees a smooth transition of a call from one base station - that is for the purpose of this project an antenna - to another. In the recent ten years, the amount of data traffic through mobile telecommunications has doubled annually, putting an enormous strain on the network and forcing operators to upgrade with more and more base stations and new features. Although 3G and 4G are responsible for data traffic in most countries, GSM still provides more than 80% of the coverage for mobile devices around the world. Due to the increase in data traffic, 3G and 4G need to use more and more frequencies at the expense of GSM. An optimization of the GSM network is thus vital. In this project, we research two methods to automatically choose the parameters of interest (PoI) that govern the handover feature in each cell which is, roughly speaking, the area of coverage of one antenna. In one of these methods, the choice of cell- and cell-to-cell-specific parameters has its origins in control theory while the other method is based on mathematical optimization. In the mathematical sense, our goal is to optimize the quality of service over PoIs. Extensive simulations have been run using these PoIs in order to evaluate if and how the two different methods can effectively be used in reality. Several useful insights have been gained that will provide the basis for future work. The optimization approach in particular has proved to deliver good results within the limitations of the simulated environment used for testing.

  • 8.
    Angerborn, Felix
    Linköping University, Department of Computer and Information Science, Human-Centered systems.
    Better text formatting for the mobile web with javascript2015Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    As people read more and longer texts on the web, the simple formatting options that exists in todays browsers creates worse results than necessary. On behalf of Opera Software in Linköping, a better algorithm has been implemented in Javascript with the purpose of delivering a visually better experience for the reader. The implementation is first and foremost for mobile devices and therefore a large part of the thesis has been the evaluation and optimization of performance. 

  • 9.
    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.

  • 10.
    Norén, Olof
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials.
    Epitaxial and bulk growth of cubic silicon carbide on off-oriented 4H-silicon carbide substrates2015Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The growth of bulk cubic silicon carbide has for a long time seemed to be something for the future. However, in this thesis the initial steps towards bulk cubic silicon carbide have been taken. The achievement of producing bulk cubic silicon carbide will have a great impact in various fields of science and industry such as for example the fields of semiconductor technology within electronic- and optoelectronic devices and bio-medical applications. The process that has been used to grow the bulk cubic silicon carbide is a modification of the seeded sublimation growth, and the seeds have been grown by sublimation epitaxy. Selected samples have been characterized with a variety of different methods. The surface morphology of the samples has been examined using optical microscope, atomic force microscope and scanning electron microscope. The crystal structure has been investigated by the methods X-ray diffraction and transmission electron microscopy. The electrical resistance of the grown seeds was evaluated by four probe measurements. High crystal quality seeds have been grown with semiconductor properties and bulk silicon carbide was demonstrated using the seeds.

  • 11.
    Nedstrand, Paul
    et al.
    Linköping University, Department of Computer and Information Science. Linköping University, Faculty of Science & Engineering.
    Lindgren, Razmus
    Linköping University, Department of Computer and Information Science. Linköping University, Faculty of Science & Engineering.
    Test Data Post-Processing and Analysis of Link Adaptation2015Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Analysing the performance of cell phones and other wireless connected devices to mobile networks are key when validating if the standard of the system is achieved. This justies having testing tools that can produce a good overview of the data between base stations and cell phones to see the performance of the cell phone. This master thesis involves developing a tool that produces graphs with statistics from the trac data in the communication link between a connected mobile device and a base station. The statistics will be the correlation between two parameters in the trac data in the channel (e.g. throughput over the channel condition). The tool is oriented on analysis of link adaptation and by the produced graphs the testing personnel at Ericsson will be able to analyse the performance of one or several mobile equipments. We performed our own analysis on link adaptation using the tool to show that this type of analysis is possible with this tool. To show that the tool is useful for Ericsson we let test personnel answer a survey on the usability and user friendliness of it.

  • 12.
    Bergström, Joakim
    et al.
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, The Institute of Technology.
    Nilsson-Sundén, Hampus
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, The Institute of Technology.
    Cost effective optimization of system safety and reliability2015Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    A method able to analyze and optimize subsystems could be useful to reduce project cost, increase subsystem reliability, improve overall aircraft safety and reduce subsystem weight. The earlier the optimization of development of an aircraft in the design phase can be performed, the better the yield of the optimization becomes. This master thesis was formed in order to construct an automatic analysis method, implementing a Matlab script, evaluating devices forming aircraft subsystems using a Genetic Algorithm. In addition to aircraft subsystems, the method constructed in the work is compatible with systems of various industries with minor modifications of the script.

  • 13.
    Börjesson, Veronica
    et al.
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, The Institute of Technology.
    Jonsson, Karolin
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, The Institute of Technology.
    Evaluating the user experience in mobile games using session recording tools2015Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    This thesis work examines how the user experience of mobile games can be evaluated with the use of session recording tools. The thesis project was carried out at the mobile games development company MAG Interactive, and the aim was to produce a workflow for the company with guidelines for how to conduct user testing with session recording tools for mobile devices. In order to evaluate the tools and services, and to develop the workflow, several user tests have been conducted. When using mobile session recording tools, it is possible to record the screen of the device, the microphone input and in some tools also the front camera input while the user is playing the game. Recording the test session makes it easier to understand and evaluate the player experience of the game and also to identify usability issues. The thesis also covers other parts necessary when conducting user testing besides the actual session recording tool. These are test set up (instructions, tasks etc.), integration, distribution of the test and the application and also analysis of the recorded test session.

  • 14.
    Zeitler, Jonas
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, The Institute of Technology.
    Adaptive rendering of celestial bodies in WebGL2015Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    This report covers theory and comparison of techniques for rendering massive scale 3D geospa- tial planet data in a web browser. It also presents implementation details of a few of these tech- niques in WebGL and Javascript, using the Three.js [1] 3D library. The thesis project is part of the implementation of Unitea, a web based education platform for interactive astronomy visualizations. Unitea is a derivative of Uniview, which is a fulldome interactive simulation of the universe. A major part of this thesis is dedicated to the implementa- tion of Hierarchical Level of Detail (HLOD) modules for Three.js based on the theory presented by T. Ulrich [2] and later generalized by Cozzi and Ring [3]. HLOD techniques are dynamic level of detail algorithms that represent the surface of objects as accurately as possible from a certain viewing angle. By using space partitioning tree-structures, view based error metrics and culling techniques detailed representations of the objects (in this case planets) can be efficiently rendered in real-time. The modules developed provide a general-purpose library for rendering planets (or other spher- ical objects) with dynamic level of detail in Three.js. The library also features connections to online web map services (WMS) and tile services.

  • 15.
    Magnusson, Karolina
    Linköping University, Department of Biomedical Engineering. Linköping University, Faculty of Science & Engineering.
    Mechanical heart rate detection using cardiogenic impedance - a morphology approach2015Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The objective of this thesis is to examine the possibility to determine the mechanical heart rate using intracardiac impedance in the time domain. Deducing the mechanical heartrate from the impedance could help improve the performance of implanted devices that today depend on the measurement of the heart’s electrical activity. Cardiogenic – also known as intracardiac – impedance is based on the difference in conductivity between heart muscle tissue and blood, making the impedance vary as the heart is filled and emptied. The data used in this thesis was acquired from three previous studies performed by St Jude Medical, two clinical and one preclinical. Two impedance measurement configurations were chosen from these studies, one bipolar and one quadropolar. To deduce the heart rate from the intracardiac impedance six algorithms were evaluated. Three using continuous peak detection and three evaluating small frames of the impedance signal.The peak detection algorithms were peak detection on the impedance signal itself, on its derivative  and on its integral. The three others were an Auto Correlation Function (ACF), an Average Magnutide Difference Function (AMDF) and an Average Wave Comparison Function (AWCF). In order to assess the heart rates deduced from the intracardiac impedance by the algorithms, these rates were compared to both the IEGM or the ECG (depending on which study was at hand) and the blood pressure.

    Several issues affected the performance of the algorithms. Impedance morphology can vary between patients. Some display so called “double peaks”, making it hard to decide whether a patient has for example a pulse of 80 bpm or of 160 bpm. The impedance morphology was also affected by amplitude modulation with the respiration frequency which in some patients cause difficulties to analyze the impedance signal. The results show that the two impedance measurement configurations perform equally well and that the ACF method was the overall best performing algorithm. They also show that individual patient impedance morphology has a large influence on the results and for future studies it should therefore be interesting to calibrate the algorithms for each patient, as this should improve performance.

  • 16.
    Häger, Emil
    Linköping University, Department of Electrical Engineering, Integrated Circuits and Systems. Linköping University, Faculty of Science & Engineering.
    Performance Evaluation of Medium-Power Voltage Inverters2015Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Power inverters, used to convert DC power to AC, are often used in e.g. solar power applications. However, they tend to be impractically large and expensive; as such, power miniaturization is an active research area. In this thesis, several classes of modern power inverters are evaluated and compared with regards to size, efficiency and output quality in order to identify areas of potential improvement. Methods for estimation of THD, power losses and input ripple are created and verified against a simulation of a five-level neutral-point-clamped inverter with SPWM control. Finally, this design is implemented physically and is found to achieve 94.5% efficiency and 7% THD under low voltage laboratory conditions, while remaining smaller than an average textbook.

  • 17.
    Ericsson, Marcus
    Linköping University, Department of Electrical Engineering, Information Coding. Linköping University, Faculty of Science & Engineering.
    Transmission, Storage, and Visualization of Data with ANT+2015Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Ultra low-powers wireless technology sensors uses when devices is used to consumeslow power. ANT+ sensors can run for years on a single coin battery. In thethesis the ANT+ sensor data is used in an application that can store and visualizethe data.

  • 18.
    Borgstedt, Jan
    Linköping University, Department of Computer and Information Science, Human-Centered systems. Linköping University, Faculty of Science & Engineering.
    Utveckling av ett kommunikationsprotokoll för datainsamling från medicinteknisk utrustning2015Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Patient data management systems (PDMS) have to handle various data sources such as patient monitors, ventilators and pumps. The objective of this work was to develop a general and maintainable medical protocol and a database system to manage patient data from various medical instruments in intensive care.

    A prototype system with an experimental communication protocol and a database was created and evaluated technically with a Philips MP30 patient monitor system. The system was developed in the programming language C# with a MySQL database. The study shows that it is possible to create a protocol that handles various medical data sources. The report describes the developed protocol, data structures, architecture and related communication standards used in healthcare.

  • 19.
    Söderberg, Christian
    Linköping University, Department of Computer and Information Science, Human-Centered systems. Linköping University, Faculty of Science & Engineering.
    Heuristisk utvärdering av typografi i responsiva gränssnitt2015Independent thesis Basic level (degree of Bachelor), 10,5 credits / 16 HE creditsStudent thesis
    Abstract [en]

    This study aims to develop a set of heuristics for evaluating typography in responsive user interfaces. By combining traditional design principles for typography with principles for responsive web design, twelve heuristics has been created. This list of heuristics has been used by graphic designers and user interface developers in two heuristic evaluations. The heuristics ability to lead to finding typographic problems in two different responsive interfaces has been analyzed, and the results from the user interface developers has been in main focus, since the goal was to create a tool for developers with a lack of knowledge in typography to create interfaces with better design. The results has shown that even though developers struggle to find the samt amount of typography problems as graphic designers, the heuristics does help to find problem. Even so, this indicate that a heuristic evaluation with non-typographic experts may need a few more participants than an evaluation with only typographic experts. The results also shows that an evaluation of a responsive user interface is best made through evaluation of the same interface on different devices with different screen sizes.

  • 20.
    Szilassy, Martin
    et al.
    Linköping University, Department of Electrical Engineering, Automatic Control. Linköping University, Faculty of Science & Engineering.
    Örn, Daniel
    Linköping University, Department of Electrical Engineering, Automatic Control. Linköping University, Faculty of Science & Engineering.
    Low Energy GPS Positioning: A device-server approach2015Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    GPS is widely used for localization and tracking, however traditional GPS receivers consume too much energy for many applications. This thesis implements and evaluates the performance of a low energy GPS solution, including a working hardware prototype, that reduces energy consumption significantly. The prototype operates for 2 years on a coin cell battery, sampling every minute. The corresponding time for a traditional receiver is 2 days. The main difference is that a traditional receiver requires 30 seconds of data to estimate a position; this solution only requires 2 milliseconds of data, a reduction of a factor 15 000. The solution consists of a portable device, sampling the GPS signal, and server software that utilizes Doppler navigation and Coarse Time Navigation to estimate positions. The median positioning error is at most 38 meters in our tests. We expect that this solution will enable positioning for billions of devices in the near future.

  • 21.
    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.

  • 22.
    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.

  • 23.
    Sami, Abdul Wahab
    Linköping University, Department of Electrical Engineering, Integrated Circuits and Systems. Linköping University, The Institute of Technology.
    Area Efficient ADC for Low Frequency Application2014Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Analog to digital converters (ADCs) are the fundamental building blocks in communication

    systems. The need to design ADCs, which are area and/or power efficient, has been common.

    Various ADC architectures, constrained by resolution capabilities, can be used for this purpose.

    The cyclic algorithmic architecture of ADC with moderate number of bits comes out to be

    probably best choice for the minimum area implementation. In this thesis a cyclic ADC is

    designed using CMOS 65 nm technology. The ADC high-level model is thoroughly explored and

    its functional blocks are modelled to attain the best possible performance. In particular, the

    nonlinearities which affect the cyclic/algorithmic converter are discussed. This ADC has been

    designed for built-in-self-testing (BiST) on a chip. It is only functional during the testing phase,

    so power dissipation is not a constraint while designing it. As it is supposed to be integrated as

    an extra circuitry on a chip, its area really matters.

    The ADC is designed as 10-bit fully differential switch-capacitor (SC) circuit using 65nm

    CMOS process with 1.2V power supply. A two stage Operational Transconductance Amplifier

    (OTA) is used in this design to provide sufficient voltage gain. The first stage is a telescopic

    OTA whereas the second is a common source amplifier. The bottom plate sampling is used to

    minimize the charge injection effect which is present in the switches.

  • 24.
    Kim, Persson
    Linköping University, Department of Electrical Engineering, Integrated Circuits and Systems. Linköping University, The Institute of Technology.
    Design av effektelektronikkort till NI ELVIS II2015Independent thesis Basic level (university diploma), 10,5 credits / 16 HE creditsStudent thesis
    Abstract [sv]

    Det här arbetet handlar om designa ett effektelektronikkort till National Instruments utvecklingsplattform ELVIS II, som skakunna styras från programmet LabVIEW. Kortet är tänkt att kunna användas i kurser inom effektelektronik på högskolenivåoch har designats för att passa ELVIS II's hårdvaruspecifikationer. I arbetet har alla kretsar byggts upp och simulerats iMultisim. Kretsarna som designats är en step-up-konverterare, en step-down-konverterare, en likriktare, en växelriktare ochen variabel last. Simuleringarna visade att kretsarna fungerar som tänkt och vad som skiljer sig från det teoretiska. Någotsom ofta visade sig i simuleringarna var att strömförbrukningen under korta perioder kraftigt kan överstiga det ELVIS II kanleverera, vilket behöver undersökas närmare. Rapporten innehåller scheman och simuleringsresultat från alla kretsar, vadsom är kvar att lösa på dessa och hur dessa kan anslutas till ELVIS II.

  • 25.
    Danielsson, William
    et al.
    Linköping University, Department of Computer and Information Science. Linköping University, The Institute of Technology.
    Waldmann, Sebastian
    Linköping University, Department of Computer and Information Science. Linköping University, The Institute of Technology.
    Avoiding Unnecessary 3G Data Transmission Through Mobile Sensors2014Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    In recent years, instant messaging (IM) has started to replace short message service (SMS) in communication. IM offers more functionality but there is a great downside. IM demands more power and drains the mobile device battery faster. This paper shows the energy consumption of  IM when the user is not using the application and how the consumption  can be reduced by enabling mobile sensors and sending fewer packets by the application. We began by investigating the various sensors that are supported by mobile devices. With the retrieved vendor information, we evaluated the different sensors and chose two sensors, light sensor and proximity sensor in order to study their use for reduction of energy in  an instant messaging scenario. These two sensors can together estimate if the mobile device is placed in the pocket of the user. The development of a simple IM application was completed and sensors were used to create an extension to the application. The extension would lengthen the interval between the updates of the automatic update function when the mobile was inactive, reducing the energy consumption.

    Two types of tests were performed. The first test evaluated if the extension would correctly deduce that the mobile device was placed inside a pocket. The mobile device with the pocket-aware application was used in different common situations and the tests showed that the extension made a correct computation in seven of nine situations. The faulty situations were when the mobile device is placed with the screen faced down to a surface. The second test compared the energy consumed by a pocket-aware application compared to a mobile device without our extension. Based on the results that we retrieved, we estimated that during a one minute period the pocket-aware application with an update interval of ten seconds could save on average 12% and could save on average 62% when the update interval was increased to fifteen seconds.

  • 26.
    Polis, Rihards
    Linköping University, Department of Computer and Information Science, Software and Systems. Linköping University, The Institute of Technology. Riga Technical University.
    EnergyBox: Tool improvement and GUI2014Independent thesis Basic level (degree of Bachelor), 15 credits / 22,5 HE creditsStudent thesis
    Abstract [en]

    EnergyBox is a parametrised estimation tool that uses packet traces as input to simulate the energy consumption of communication in mobile devices. This tool models the transmission behaviour of a smart phone by analysing a recorded packet trace from the device. The purpose of the thesis is to reimplement the original EnergyBox energy consumption modelling tool. The project aims to develop support for a graphical user interface (GUI) and a code base that is easier to modify and maintain.

    The motivation for the reimplementation of the tool is to simplify its usage and to structure the code so that new features can be added. The existing features such as the calculation of total power consumed by the packet trace and the modelling of a device's energy states are reimplemented and new features are developed. Among the new features, a GUI is added to simplify the usage of the application features such as the detection of the recording device's IP address and the ability to alter the configuration parameters used as input to the energy model.

    The application is written with a GUI and modularity in mind. This is achieved using Java's proprietary new GUI framework - JavaFX, which supports built-in chart and graph GUI elements, that can be easily integrated and supported. The energy modelling engines follow the semantics of the original implementation and the evaluation shows that the new implementation's results are identical to the original tool in 94.94% of the tested cases.

  • 27.
    Khan, Muhammad Awais
    Linköping University, Department of Electrical Engineering, Electronics System. Linköping University, The Institute of Technology.
    A Study on the Aliasing-image Problem in I/Q Modulators Employing RF-DACs2013Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    In today’s world of high-speed communication, data-converters are playing a vital role. The purpose of this project is to analyze the aliasing image problem that occurs in quadrature I/Q modulators utilizing radio frequency digital-to-analog converters (RF-DACs). The RF-DAC is considered to be high-speed DAC that operates in higher GHz region. These high performance DACs are becoming the most essential part of the upcoming future communication devices like next generation radars and telecommunication systems. Some I/Q modulators are implemented in this thesis. The aim is to identify the unwanted signal that is trying to distort the desired output.

    In this thesis, the work is divided into two main parts. First is the aliasing image verification and second is the implementation of the I/Q modulators. Begin with the assessment of the aliasing image through sketching the spectrum using Matlab tools. Also mathematically the calculation is derived to support the flow. In the next part, four different architectures are implemented focusing on image rejection ratio (IRR) calculation while the maximum achievable rejection ratio is 119 dB using the RF-DAC. Lastly the effect of discrete local oscillation (LO) is shown. A comparison plot is drawn, comparing the effect of a discrete-LO at different bit levels vs. IRR variation. It shows a nice picture of IRR dependence on the perfect matching and not on the signal shaping. 

  • 28.
    Stenbeck, Marcus
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, The Institute of Technology.
    Automatisk testning av WebGL på mobil- och desktopenheter2014Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    WebGL is a standard for drawing graphics in a web browser. Currently it isn’t widely understood how consistently WebGL performs across a majority of the de- vices that support it. Determining if an image looks correct to a human observer is an interesting problem. The solution for this is useful when developing WebGL applications, since a developer could make better informed decisions during de- velopment. The differences in capability between WebGL implementations are studied, and a few factors are selected that likely will contribute to variations in the rendered output. These factors are found by studying the WebGL specification documen- tation, and in the cases where it is ambiguous, further, authorative sources have contributed to the choice of factors studied. A prototype testing system is developed, including a tool for simulating imple- mentation differences. Two image processing algorithms are evaluated for their suitability in an automatic testing system. For testing, four test cases are devel- oped. The testing system is run with the test cases on wide range of devices, both mobile and desktop. The results show that image processing is not suitable alone the source for deter- mining a test success or failure. However, some promise is shown in using image processing as one component in a fully automatic testing system. Furthermore, developing test cases that perform as the test constructor intends is proven to be a challenge in itself.

  • 29.
    Carlsson, Jacob
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, The Institute of Technology.
    Isolated WiFi Environments2015Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    WiFi is becoming common in households and digital devices needs to support it. At the same time the devices are getting smaller and the Ethernet port may seem superfluous. When testing these devices the test environment needs to be able to provide WiFi connectivity. The tests may be focused on testing WiFi but it could also be the only network connectivity and thus needs to be very reliable. With a large number of devices in a small physical area a normal WiFi setup would have a density of devices that is too high for today’s1 WiFi standards. A combination of wired physical medium and physical isolation was considered.

  • 30.
    Kantzon, David
    et al.
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, The Institute of Technology.
    Lahti, Sebastian
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, The Institute of Technology.
    Over voltage protection device for ROV2014Independent thesis Basic level (degree of Bachelor), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Supplying power to equipment always imposes a risk of damaging it. This risk is apparent in every application whether it be an industrial or a home appliance. One of these harmful occurrences is something like lightning which introduces a potentially harmful voltage in the system. To reduce the risk of damage significantly an over-voltage protection device is needed. Devices which deal with this problem are common in any electrical equipment and this report deals with the construction and evaluation of one such unit.

    The device or equipment needing protection in this case is an industrial underwater robot built by Ocean Robotics. In order for this robot to operate safely it needs several protective measures where an over-voltage protection system is one of them. This system provides protection against over-voltages appearing on the main cable supplying the robot, where the input voltage ranges from 200 to 600 volts. As the desired voltage output range from the over-voltage system is 250 to 350 volts it must be able to handle significant power in some cases.

    Due to the restrictions on functionality given by the contractor a novel way of achieving the goals was tested. The completed prototype can only dissipate 70 watts of power which is far from the required 1500 watts which was specified in the sheet of requirements. However, this system could be used to protect equipment with lower requirements for power handling capability and with added time and effort it could possibly meet the requirements for this project as well.

  • 31.
    Ubillis, Amaru
    Linköping University, Department of Computer and Information Science, Human-Centered systems. Linköping University, The Institute of Technology.
    Evaluation of Sprite Kit for iOS game development2014Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The purpose with this thesis is to investigate whether Sprite Kit is a good tool to simplify the development process for game developers when making 2D games for mobile devices. To answer this question a simple turn based strategy game has been developed with Sprite Kit. Sprite Kit is a game engine for making 2D games released by Apple.

    Based on the experience I got during the development I will go through and discuss some of the most important tools provided by the game engine and how they helped us to complete our game.

    The conclusions I reached after making a game with Sprite Kit is that the frame- work provides all the tools necessary for creating a simple 2D mobile game for iOS. Sprite Kit hides much of the lower level details and gives the game de- veloper comprehensive development support. This helps the game developer to save a lot of time and focus more on the gameplay when creating a game. 

  • 32.
    Andersson, Filip
    Linköping University, Department of Computer and Information Science. Linköping University, The Institute of Technology.
    GPGPU-Sim2014Independent thesis Basic level (university diploma), 10,5 credits / 16 HE creditsStudent thesis
    Abstract [en]

    This thesis studies the impact of hardware features of graphics cards on performance of GPU computing using GPGPU-Sim simulation software tool. GPU computing is a growing topic in the world of computing, and could be an important milestone for computers. Therefore, such a study that seeks to identify the performance bottlenecks of the program with respect to hardware parameters of the devvice can be considered an important step towards tuning devices for higher efficiency.

    In this work we selected convolution algorithm - a typical GPGPU application - and conducted several tests to study different performance parameters. These tests were performed on two simulated graphics cards (NVIDIA GTX480, NVIDIA Tesla C2050), which are supported by GPGPU-Sim. By changing the hardware parameters of graphics card such as memory cache sizes, frequency and the number of cores, we can make a fine-grained analysis on the effect of these parameters on the performance of the program.

    A graphics card working on a picture convolution task releis on the L1 cache but has the worst performance with a small shared memory. Using this simulator to run performance tests on a theoretical GPU architecture could lead to better GPU design for embedded systems.

  • 33.
    Almquist, Mathias
    et al.
    Linköping University, Department of Computer and Information Science, Software and Systems. Linköping University, The Institute of Technology.
    Almquist, Viktor
    Linköping University, Department of Computer and Information Science, Software and Systems. Linköping University, The Institute of Technology.
    A study on Android games: 3G energy consumption, CPU-utilization and system calls2015Independent thesis Basic level (university diploma), 10,5 credits / 16 HE creditsStudent thesis
    Abstract [en]

    The popularity of mobile games has increased drastically during the recent years andmany people use them as their main source of entertainment. Mobile gamescommunicate with other devices over the network which consumes a lot of energy,especially when connected to cellular networks (e.g., 3G). This high energy expensecan feel unjustified to the player since always-on network connectivity is not requiredin order to play most games.Furthermore, the number of malware-infected applications in offical applicationstores has increased significantly in the recent years. These malware-infectedapplications can gain unrestricted access and control of users phones which can be athreat to security. Information about the behaviour characteristics of games can beused to develop or improve systems for detecting malware applications.In this thesis, 20 popular Android games are analysed with a focus on the datacommunication, CPU utilization and system call behaviour. The main subject of thedata communication study is the 3G communication energy consumed by games. Thesystem call study aims at quantifying the number and type of calls used by games.This may be useful in a further study of harmful behaviour by apps.The profiling results presented in this report show that the communication energyvaries drastically among games. Games with a very similar gameplay can consumevery different amounts of energy which indicates that there is room for improvementsin many of the games. Ad-free games consume significantly less energy than gamesthat use in-app advertisements. The results show that improving the advertisementfetching policy could reduce the energy consumption of these games. The majority ofthe games can be played without network connectivity and therefore thecommunication energy consumed could be completely avoided. The thesis alsoshows that games use a wide variety of system calls and that many of the system callsare common among the games.

  • 34.
    Cuello, Rosandra
    Linköping University, Department of Computer and Information Science. Linköping University, The Institute of Technology.
    Providing Support for the Movidius Myriad1 Platform in the SkePU Skeleton Programming Framework2014Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The Movidius Myriad1 Platform is a multicore embedded platform primed to offer high performance and power efficiency for computer vision applications in mobile devices. The challenges of programming multicore environments are well known and skeleton programming offers a high-level programming alternative for parallel computing, intended to hide the complexities of the system from the programmer. The SkePU Skeleton Programming Framework includes backend implementations for CPU and GPU systems and it has the capacity to support more platforms by extending its backend implementations. With this master thesis project we aim to extend the SkePU Skeleton Programming Framework to provide support for execution in the Movidius Myriad1 embedded platform. Our SkePU backend for Myriad1 consists on a set of macros and functions to compose the different elements of a Myriad1 application, data communication structures to exchange data between the host systems and Myriad1, and a helper script and auxiliary files to generate a Myriad1 application.Evaluation and testing demonstrate that our backend is usable, however further optimizations are needed to obtain good performance that would make it practical to use in real life applications, particularly when it comes to data communication. As part of this project, we have outlined some improvements that could be applied to obtain better performance overall in the future, addressing the issues found with the methods of data communication.

  • 35.
    Rangraz, Masood
    Linköping University, Department of Culture and Communication, Language and Culture. Linköping University, Faculty of Arts and Sciences.
    The Uses of the Discourse Markers ‘well’, ’you know’ and ‘I mean’ in News Interviews2014Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    This study is about the use of three Discourse Markers (henceforth DMs) in news interviews. It is an attempt to demonstrate how well, you know and I mean are employed in news interviews. It also shows what participants accomplish using the DMs as rhetorical devices.

  • 36.
    Maddula, Ravi
    Linköping University, Department of Electrical Engineering, Electronic Devices. Linköping University, The Institute of Technology.
    Near threshold operation of 16-bit adders in 65nm CMOStechnology2014Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The main objective of the thesis is to implement different architectures of 16-bit adders such as; Ripple CarryAdder (RCA), Manchester Carry Chain Adder (MCCA) and Kogge Stone Adder (KSA), in 65nm CMOS technology and to study their performance in terms of power, operating frequency and speed at near threshold operating regions. The performance of these adders are evaluated and compared with each other and a final conclusion is made as to which adder structure is more suitable for implementation in a 65nmtechnology for low power applications. Several optimisation techniques are performed for the adders to reduce the delay and power consumption. Propagation delay is the most critical or essential parameter to be considered, hence, to minimise the delay of the adder, a technique called sizing and ordering are required for the transistors. The purpose of the thesis is to make a fair comparison among adders over several metrics which include linearity, delay and power.

    Simulation results of MCCA achieved a greater significant performance upon or over RCA and KSA, and proved it is the best suitable adder for low power applications.

  • 37.
    Skog, Albert
    et al.
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, The Institute of Technology.
    Westerberg, Karl
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, The Institute of Technology.
    Graphene on Silicon Carbide Chip for Biosensing Applications2014Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Graphene is a single layer of carbon atoms, laid out in a hexagonal lattice. The material has remarkable properties that opened up several new research areas since its discovery in 2004. One promising field is graphene based biosensors, where researchers hope to create new devices that are smaller, cheaper and more reliable than those based on today’s technology. Among several manufacturing methods, graphene grown on silicon carbide is one of the promising ones for biosensing. A chip design has been developed in order to support research into graphene on silicon carbide as a base material for biosensors. Along with the chip, a holder for electrochemical measurements has been designed and an investigation into the requirements of a custom measurement device for the sensor has been undertaken.

  • 38.
    Andersson, Rikard
    Linköping University, Department of Electrical Engineering. Linköping University, The Institute of Technology.
    FFT Hardware Architectures with Reduced Twiddle Factor Sets2013Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The goal of this thesis has been to reduce the hardware cost of SDF FFTs. Inorder to achieve this, two methods for simplifying rotations in FFTs are presented:Decimation and Reduction. When applied, these methods reduce the total amountof angles that the rotators need to rotate, as well as the total angle count of theFFT. This is useful for constant shift and add based rotators, as their hardwarecost are typically dependent on the amount of angles it needs to calculate.Decimation works by splitting a large twiddle factor into a smaller one plusan additional small rotator in series. This allows for the possibility to implementlarge FFTs without needing any large twiddle factors. Reduction is a method thattakes a twiddle factor and simplifies it by removing one angle from the rotator.This can be done without adding any hardware cost if applied correctly.In addition to the methods, the thesis also includes proposed designs for 64- upto 1024-point FFTs, as well as post-implementation results for a 32- and 64-pointFFT.

  • 39.
    Barsomo, Milad
    et al.
    Linköping University, Department of Computer and Information Science. Linköping University, The Institute of Technology.
    Hurtig, Mats
    Linköping University, Department of Computer and Information Science. Linköping University, The Institute of Technology.
    Device-aware Adaptation of Websites2014Independent thesis Basic level (degree of Bachelor), 10,5 credits / 16 HE creditsStudent thesis
    Abstract [en]

    The use of handheld devices such as smart phones and tablets have exploded in the last few years. These mobile devices differ from regular desktops by having limited battery power, processing power, bandwidth, internal memory, and screen size. With many device types and with mobile adaptation being done in many ways, it is therefore important for websites to adapt to mobile users. This thesis characterise how websites currently are adapting to mobile devices. For our analysis and data collection, we created a tool which sends modified HTTP GET requests that makes the web server believe the GET requests were sent from a smart phone, tablet, or a regular desktop. Another tool then captured all the HTTP packets and let us analyse these for each platform. We chose to analyse the top 500 most popular websites in the world and the top 100 websites from 15 different categories fetched directly from www.alexa.com. Among other things, we observed that of the total HTTP objects fetched to render an average website, mobile or non-mobile, more than half of the objects were images. Another conclusion is that a website fetched by an iPhone 4 device is more heavily reduced in amount of images than a Nexus 7.

  • 40.
    Lin, Keng-Yu
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Thin films for thermoeletric applications2014Independent thesis Advanced level (degree of Master (Two Years)), 30 credits / 45 HE creditsStudent thesis
    Abstract [en]

    Global warming and developments of alternative energy technologies have become important issues nowadays. Subsequently, the concept of energy harvesting is rising because of its ability of transferring waste energy into usable energy. Thermoelectric devices play a role in this field since there is tremendous waste heat existing in our lives, such as heat from engines, generators, stoves, computers, etc. Thermoelectric devices can extract the waste heat and turn them into electricity. Moreover, the reverse thermoelectric phenomenon has the function of cooling which can be applied to refrigerator or heat dissipation for electronic devices. However, the energy conversion efficiency is still low comparing to other energy technologies. The efficiency is judged by thermoelectric figure of merit (ZT), defined by Seebeck coefficient, electrical conductivity and thermal conductivity. In order to improve ZT, thin film materials are good candidates because of their structural effects on altering ZT. 

     

    Ca3Co4O9 thin films grown by reactive radio frequency magnetron sputtering followed by post-annealing process is studied in this thesis. Structural properties of the films with the evolution of elemental ratio (Ca/Co) of calcium and cobalt have been investigated. For the investigations, three samples having elemental ratio 0.82, 0.72, and 0.66 for sample CCO1, CCO2 and COO3, respectively, have been prepared. Structural properties of the films have been investigated by X-ray diffraction (XRD) θ-2θ and pole figure analyses. Surface morphology of the films has been investigated by scanning electron microscopic (SEM) analyses. The highly oriented and phase pure epitaxial Ca3Co4O9 thin films were obtained in the end.

     

    Mixing of ScN and CrN to obtain ScxCr1-xN solid solution thin films by DC magnetron sputtering is the other task in this thesis. Growth of ScN and CrN thin films were studied first in order to get the best mixed growth conditions. The phase shifts between ScN (111) and CrN (111) peaks were observed in mixed growth films by XRD θ-2θ measurements, indicating the formation of ScxCr1-xN. Surface morphology of the films were investigated by SEM. The (111)-oriented ScxCr1-xN thin films with decent surface smoothness grown by DC magnetron sputtering at 600 °C in pure nitrogen with bias were developed. 

  • 41.
    Walldén, Johan
    Linköping University, Department of Electrical Engineering, Electronic Devices. Linköping University, The Institute of Technology.
    Radiation Induced Effects in Electronic Devices and Radiation Hardening By Design Techniques2014Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The aim with this thesis has been to make a survey of radiation hardened electronics, explaining why and how radiation affects electronics and what can be done to harden it.

    The effects radiation have on electronics in general and in specific commonly used devices are explained qualitatively. The effects are divided into Displacement Damage (DD), Total Ionizing Dose (TID) and Single Event Effects (SEEs). The devices explained are MOSFETs, Silicon On Insulator (SOI) transistors, 3D-transistors, Power transistors, Optocouplers, Field Programmable Gate Arrays (FPGAs), three dimensional circuits (3D-ICs) and Flash memories.

    Different radiation hardening by design (RHBD) techniques used to reduce or to remove the negative effects radiation induces in electronics are also explained. The techniques are Annular transistors, Enclosed source/drain transistors, Guard rings, Triple Modular Redundancy (TMR), Dual Interlocked Storage Cells (DICE), Guard gates, Temporal filtering,Multiple drive, Charge dissipation, Differential Charge Cancellation (DCC), Scrubbing, Lockstep, EDAC codes and Watchdog timers.

  • 42.
    Kvist, Torbjörn
    Linköping University, Department of Computer and Information Science, Human-Centered systems. Linköping University, The Institute of Technology.
    Second screen on mobile crossplatform2014Independent thesis Basic level (degree of Bachelor), 10,5 credits / 16 HE creditsStudent thesis
    Abstract [en]

    Development of mobile applications today are increasingly difficult for developers, because there are many different devices and operating systems. This thesis will look at how a cross-platform framework can be used to develop and implement a second screen as a complement to other devices. he platforms will be evaluated in terms of how complex it is to implement the solution and how they perform under different conditions. The cross-platform frameworks that will be evaluated is OpenFL and PhoneGap.

  • 43.
    Kashfolayat, Sahar
    Linköping University, Department of Electrical Engineering, Electronic Devices. Linköping University, The Institute of Technology.
    A Study of clocking techniques to reduce Simultaneous Switching Noise (SSN) in on-chip application2011Independent thesis Advanced level (degree of Master (Two Years)), 80 credits / 120 HE creditsStudent thesis
    Abstract [en]

    Simultaneous Switching Noise (SSN) is one of the major problems in today highspeed circuits. Power-Ground voltage fluctuation is significantly increasing due to L ∗ (di/dt)) noise known as Power-Ground bounce and can be one major noise source in modern and mixed-signal circuit design.

    In this thesis first SSN and its sources are studied followed by some theoretical analysis, then we present some clock shapes that cause in SSN reduction.

    In this thesis, we investigate different clocking techniques in order to reduce SSN. The effect of rise/fall time variation, applying sinusoidal, multi-segment and harmonic suppressed clocks have been investigated and verified by proper circuit simulations.

    Multi-segment clock shape and harmonic suppression clock shape produce less noise in comparison to conventional clock, so using them as clock of the whole system can be act as noise reduction technique.

  • 44.
    Bäcklund, Jakob
    et al.
    Linköping University, Department of Computer and Information Science. Linköping University, The Institute of Technology.
    Kärnsund, Elias
    Linköping University, Department of Computer and Information Science. Linköping University, The Institute of Technology.
    Implementation of a Crowd-based InformationSharing System for Network Performance Maps2014Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    This thesis examines ways to improve the user experience of a mobile Internetconnection. We discuss how this can be achieved using dierent techniques,but primarily focus on techniques using network performance maps. We designand implement a proof-of-concept system that allows users to record networkperformance experience and share these records among each other such as toimprove their future performance.We use bandwidth measurements at locations over an area to create a networkperformance map. We examine what such maps can be used for and howit is best implemented. We also create a proof-of-concept implementation fora system creating network performance maps using multiple mobile devices.The thesis also discusses how information sharing between mobile devices usingWi-Fi networks can be done eciently. This is also something we use inour proof-of-concept implementation, when synchronizing data between mobiledevices.In summary, our Android-based proof-of-concept implementation allows usersto perform bandwidth measurements, and to share these measurements amongeach other, such as to help each other improve their network performance maps.A good such system allows users to get an overview of the network performanceover the measured area; information that can be used to optimize the Internetusage via download scheduling or bit rate adaption.

  • 45.
    Ali, Rahman
    Linköping University, Department of Electrical Engineering, Electronics System. Linköping University, The Institute of Technology.
    Design of Building Blocks in Digital Baseband Transceivers for Body-Coupled Communication2014Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Advances in communication technologies continue to increase information sharing among the people.~Short-range wireless networking technologies such as Bluetooth or ZigBee, which are mainly used for data transfer over short range, will, however, suffer from network congestion, high power consumption and security issues in the future.

    The body-coupled communication (BCC), a futuristic short-range wireless technology, uses the human body as a transmission medium. In BBC channel, a small electric field is induced onto the human body which enables the propagation of a signal between communication devices that are in the proximity or direct contact with the human body. The direct baseband transmission and simple architecture make BCC an attractive candidate for a future short-range wireless communication technology in particular applications such as body area network.

    The main focus of this thesis is on the design and implementation of digital baseband transmitter and receiver for the body-coupled communication. The physical layer (PHY) implementation of the digital baseband transmitter and receiver is inspired from the IEEE 802.3 Ethernet transmission protocol. The digital design is implemented at RTL level using hardware description language (VHDL). The functionality of the digital baseband transmitter and receiver is demonstrated by developing data transfer application layers.

  • 46.
    Chen, Huijuan
    et al.
    Linköping University, Department of Management and Engineering, Energy Systems.
    Janbakhsh, Setareh
    Linköping University, Department of Management and Engineering, Energy Systems.
    Larsson, Ulf
    university of Gavle.
    Moshfegh, Bahram
    Linköping University, Department of Management and Engineering, Energy Systems.
    Comparisons of ventilation performance of different air supply devicesin in an office environmentManuscript (preprint) (Other academic)
    Abstract [en]

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

     

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

  • 47.
    Bengtsson, Mikael
    Linköping University, Department of Electrical Engineering, Electronic Devices. Linköping University, The Institute of Technology.
    A clock driver with reduced EMI2014Independent thesis Advanced level (degree of Master (One Year)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    A clock driver that works on the principle of charging and discharging the clock network in a VLSI circuit in two steps is investigated in a few different configurations. The aim of the design is twofold:

    • to reduce the power consumption
    • to reduce the third harmonic of the clock signal, and thereby the EMI (electromagnetic interference) emitted by the clock network.

    The first should be possible to accomplish as the clock interconnect network gets charged by half the voltage during each rising transition, and the second should be possible to accomplish by carefully time the rising and falling transitions, so that the third Fourier coefficient of the resulting wave form cancels.

    The drivers are loaded by eight 16-bit adders. The drivers’ power consumption, and the spectrum of the output signal, are investigated under varying clock frequencies, power supply voltage, and driver architecture. The results are compared to a conventional square wave clock.

    The results are that while the third harmonics of the resulting output sees an improvement in all the investigated cases over the square wave clock, the power savings are, for higher clock frequencies, more than completely canceled by the extra power needed in the logic stage which controls these drivers. On the other hand, the power consumption of the new driver appears to drop below that of the conventional driver when the clock frequency drops below approximately 100MHz.

    A few suggestions for further investigations of new designs and clock wave forms are given.

  • 48.
    Chen, Yi-Ching
    Linköping University, Department of Computer and Information Science, Software and Systems. Linköping University, The Institute of Technology.
    Co-design of Fault-Tolerant Systems with Imperfect Fault Detection2014Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    In recent decades, transient faults have become a critical issue in modernelectronic devices. Therefore, many fault-tolerant techniques have been proposedto increase system reliability, such as active redundancy, which can beimplemented in both space and time dimensions. The main challenge of activeredundancy is to introduce the minimal overhead of redundancy and to schedulethe tasks. In many pervious works, perfect fault detectors are assumed to simplifythe problem. However, the induced resource and time overheads of suchfault detectors make them impractical to be implemented. In order to tacklethe problem, an alternative approach was proposed based on imperfect faultdetectors.

    So far, only software implementation is studied for the proposed imperfectfault detection approach. In this thesis, we take hardware-acceleration intoconsideration. Field-programmable gate array (FPGA) is used to accommodatetasks in hardware. In order to utilize the FPGA resources efficiently, themapping and the selection of fault detectors for each task replica have to be carefullydecided. In this work, we present two optimization approaches consideringtwo FPGA technologies, namely, statically reconfigurable FPGA and dynamicallyreconfigurable FPGA respectively. Both approaches are evaluated andcompared with the proposed software-only approach by extensive experiments.

  • 49.
    Friberg, Joy
    Linköping University, Department of Computer and Information Science, Human-Centered systems. Linköping University, The Institute of Technology.
    Evaluation of cross-platform development for mobile devices2014Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Developing an application for several platforms can be time consuming because each platform has its own operating system and different developing language. Cross-platform development makes it possible to develop an ap-plication that will work on several platforms. This report will evaluate this kind of development by doing a case study for the company CGI. The case study will evaluate which cross-platform methodology is the preferred choice for this specific vacation booking application I developed for CGI.

    The different methodologies I studied were web, hybrid, interpreted and cross-compiled. The preferred methodology for this vacation booking application I developed was in this case the hybrid alternative. When selecting this methodology I also chose two different tools and those two were Icenium and jQuery Mobile. The purpose of this report was to find out if cross-platform development can be a substitute to native programming and by evaluating and developing cross-platform I found out that it can be a substitute if the application is not to complex. In this specific case I also believe that hybrid development is a good substitute to native development for this kind of applications.

  • 50.
    Omar, Omar Jaber
    Linköping University, Department of Electrical Engineering, Electronic Devices. Linköping University, The Institute of Technology.
    An On-Chip Memory for Testing of High-Speed Mixed-Signal Circuits2013Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Mixed-signal processing systems especially data converters can be reliably tested at high frequencies using on-chip testing schemes based on memory. In this thesis, an on-chip testing strategy based on shift registers/memory (2 k bits) has been proposed for digital-to-analog converters (DACs) operating at 5 GHz. The proposed design uses word length of 8 bits in order to test DAC at high speed of 5 GHz. The proposed testing strategy has been designed in standard 65 nm CMOS technology with additional requirement of 1-V supply. This design has been implemented using Cadence IC design environment.

    The additional advantage of the proposed testing strategy is that it requires lower number of I/O pins and avoids the large number of high speed I/O pads. It therefore also solves the problem of the bandwidth limitation that is associated with I/O transmission paths. The design of the on-chip tester based on memory contains no analog block and is implemented entirely in digital domain. In the proposed design, low frequency of 1 MHz has been used outside the chip to load the data into the memory during the write mode. During the read mode, the frequency of 625 MHz is used to read the data from the memory. A multiplexing system is used to reuse the stored data during read mode to test the intended functionality and performance. In order to convert the parallel data into serial data at high frequency at the memory output, serializer has been used. By using the frequencies of 1.25 GHz and 2.5 GHz, the serializer speeds up the data from the lower frequency of 625 MHz to the highest frequency of 5 GHz in order to test DAC at 5 GHz.

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