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  • 1.
    Abrahamsson, Björn
    Linköping University, Department of Electrical Engineering.
    Architectures for Multiplication in Galois Rings2004Independent thesis Basic level (professional degree)Student thesis
    Abstract [en]

    This thesis investigates architectures for multiplying elements in Galois rings of the size 4^m, where m is an integer.

    The main question is whether known architectures for multiplying in Galois fields can be used for Galois rings also, with small modifications, and the answer to that question is that they can.

    Different representations for elements in Galois rings are also explored, and the performance of multipliers for the different representations is investigated.

  • 2.
    Abrahamsson, Lars
    Linköping University, Department of Electrical Engineering.
    A portal based system for indoor environs2006Independent thesis Basic level (professional degree), 20 points / 30 hpStudent thesis
    Abstract [en]

    The purpose of this thesis is to document the development of the graphics part of an extremely pluggable game engine/lab environment for a course in advanced game programming. This thesis is one out of five, and concerns indoor, realtime computer 3D graphics. It covers state-of-the-art techniques such as GLSL - the OpenGL Shading Language - and more well known techniques such as portal based rendering.

  • 3.
    Abrahamsson, Marcus
    Linköping University, Department of Computer and Information Science, Database and information techniques. Linköping University, The Institute of Technology.
    A platform for third-party applications on the web2013Independent thesis Basic level (degree of Bachelor), 10,5 credits / 16 HE creditsStudent thesis
    Abstract [en]

    A trend seen on the web today is to create a platform where externally developed applications can run inside some kind of main application. This is often done by providing an API to access data and business logic of your service and a sandbox environment in which third-party applications can run. By providing this, it is made possible for external developers to come up with new ideas based on your service. Some good examples on this are Spotify Apps, Apps on Facebook and SalesForce.com.

    Ipendo Systems AB is a company that develops a web platform for intellectual properties. Currently most things on this platform are developed by developers at Ipendo Systems AB. Some interest has though risen to enable external developers to create applications that will in some way run inside the main platform.

    In this thesis an analysis of already existing solutions has been done. These solutions were Spotify Apps and Apps on Facebook. The two have different approaches on how to enable third-party applications to run inside their own service. Facebook’s solution builds mainly on iframe embedded web pages where data access is provided through a web API. Spotify on the other hand hosts the third-party applications themselves but the applications may only consist of HTML5, CSS3 and JavaScript.

    In addition to the analysis a prototype was developed. The purpose of the prototype was to show possible ways to enable third-party applications to run inside your own service. Two solutions showing this were developed. The first one was based on Facebook’s approach with iframing of external web pages. The second was a slightly modified version of Spotify’s solution with only client-side code hosted by the main application. To safely embed the client side code in the main application a sandboxing tool for JavaScript called Caja was used.

    Of the two versions implemented in the prototype was the Iframe solution considered more ready to be utilized in a production environment than Caja. Caja could be seen as an interesting technique for the future but might not be ready to use today. The reason behind this conclusion was that Caja decreased the performance of the written JavaScript as well as adding complexity while developing the third-party applications.

  • 4.
    Abrahamsson, Robin
    et al.
    Linköping University, Department of Computer and Information Science, Software and Systems.
    Berntsen, David
    Linköping University, Department of Computer and Information Science, Software and Systems.
    Comparing modifiability of React Native and two native codebases2017Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Creating native mobile application on multiple platforms generate a lot of duplicate code. This thesis has evaluated if the code quality attribute modifiability improves when migrating to React Native. One Android and one iOS codebase existed for an application and a third codebase was developed with React Native. The measurements of the codebases were based on the SQMMA-model. The metrics for the model were collected with static analyzers created specifically for this project. The results created consists of graphs that show the modifiability for some specific components over time and graphs that show the stability of the platforms. These graphs show that when measuring code metrics on applications over time it is better to do this on a large codebase that has been developed for some time. When calculating a modifiability value the sum of the metrics and the average value of the metrics between files should be used and it is shown that the React Native platform seems to be more stable than native.

  • 5.
    Adolfsson, Klas
    Linköping University, Department of Electrical Engineering.
    TCP performance in an EGPRS system2003Independent thesis Advanced level (degree of Magister), 20 points / 30 hpStudent thesis
    Abstract [en]

    The most widely used protocol for providing reliable service and congestion control in the Internet is the Transmission Control Protocol (TCP). When the Internet is moving towards more use in mobile applications it is getting more important to know how TCP works for this purpose.

    One of the technologies used for mobile Internet is the Enhanced General Packet Radio Service (EGPRS) extension to the popular GSM system. This thesis presents a low-level analysis of TCP performance in an EGPRS system and an overview of existing TCP, GSM and EGPRS technologies.

    The bottleneck in an EGPRS system is the wireless link – the connection between the mobile phone and the GSM base station. The data transfer over the wireless link is mainly managed by the complex RLC/MAC protocol.

    In this thesis, simulations were made to identify some problems with running TCP and RLC/MAC together. The simulations were made using existing EGPRS testing software together with a new TCP module. The simulation software is also briefly described in the thesis.

    Additionaly, some suggestions are given in order to enhance performance, both by changing the EGPRS system and by modifying the TCP algorithms and parameters.

  • 6.
    Ahlström, Daniel
    Linköping University, Department of Computer and Information Science. Linköping University, The Institute of Technology.
    Minimizing memory requirements for deterministic test data in embedded testing2010Independent thesis Basic level (university diploma), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Embedded and automated tests reduce maintenance costs for embedded systems installed in remote locations. Testing multiple components of an embedded system, connected on a scan chain, using deterministic test patterns stored in a system provide high fault coverage but require large system memory. This thesis presents an approach to reduce test data memory requirements by the use of a test controller program, utilizing the observation of that there are multiple components of the same type in a system. The program use deterministic test patterns specific to every component type, which is stored in system memory, to create fully defined test patterns when needed. By storing deterministic test patterns specific to every component type, the program can use the test patterns for multiple tests and several times within the same test. The program also has the ability to test parts of a system without affecting the normal functional operation of the rest of the components in the system and without an increase of test data memory requirements. Two experiments were conducted to determine how much test data memory requirements are reduced using the approach presented in this thesis. The results for the experiments show up to 26.4% reduction of test data memory requirements for ITC´02 SOC test benchmarks and in average 60% reduction of test data memory requirements for designs generated to gain statistical data.

  • 7.
    Ahmed, Tanvir
    et al.
    Linköping University, Department of Electrical Engineering. Linköping University, Faculty of Science & Engineering.
    Garrido, Mario
    Linköping University, Department of Electrical Engineering, Electronics System. Linköping University, The Institute of Technology.
    Gustafsson, Oscar
    Linköping University, Department of Electrical Engineering, Electronics System. Linköping University, The Institute of Technology.
    A 512-point 8-parallel pipelined feedforward FFT for WPAN2011In: 2011 Conference Record of the Forty Fifth Asilomar Conference on Signals, Systems and Computers (ASILOMAR), IEEE , 2011, p. 981-984Conference paper (Refereed)
    Abstract [en]

    This paper presents a 512-point feedforward FFT architecture for wireless personal area network (WPAN). The architecture processes a continuous flow of 8 samples in parallel, leading to a throughput of 2.64 GSamples/s. The FFT is computed in three stages that use radix-8 butterflies. This radix reduces significantly the number of rotators with respect to previous approaches based on radix-2. Besides, the proposed architecture uses the minimum memory that is required for a 512-point 8-parallel FFT. Experimental results show that besides its high throughput, the design is efficient in area and power consumption, improving the results of previous approaches. Specifically, for a wordlength of 16 bits, the proposed design consumes 61.5 mW and its area is 1.43 mm2.

  • 8.
    Ahrengart, Hugo
    et al.
    Linköping University, Department of Computer and Information Science.
    Borg, Therese
    Linköping University, Department of Computer and Information Science.
    Magnuson, David
    Linköping University, Department of Computer and Information Science.
    Nilsson, Victor
    Linköping University, Department of Computer and Information Science.
    Partain, Beatrice
    Linköping University, Department of Computer and Information Science.
    Voss-Lagerlund, Carl
    Linköping University, Department of Computer and Information Science.
    Wagner, Mattias
    Linköping University, Department of Computer and Information Science.
    Awesome Fragrance Company: Utveckling av en e-butik för parfymprover2016Independent thesis Basic level (degree of Bachelor), 12 credits / 18 HE creditsStudent thesis
    Abstract [en]

    This bachelor's thesis accounts for the results and takeaways from the process of developing the web application for Awesome Fragrance Company. The goal of this thesis is to provide an increased understanding of how a usable web application can be designed, by studying the development of an online store with the purpose of selling fragrance samples. The agile method Scrum has been the foundation of the development, and based on this, the focus has been to develop a continuously deliverable product, where functionality is added in increments. By starting with a rough prototype and then gradually adjusting the final vision for the product based on feedback, the group has developed an online store which, according to users, is usable and intuitive. Thus, the group has created a foundation for further research on usable web applications, which was the goal of the project.

  • 9.
    Al Haji, Ghazwan
    et al.
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, Faculty of Science & Engineering.
    Fowler, Scott
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, Faculty of Science & Engineering.
    Andersson Granberg, Tobias
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, Faculty of Science & Engineering.
    Smart traffic calming measures for smart cities - a pre-study2018Report (Other academic)
    Abstract [en]

    Traffic calming measures, such as speed bumps and elevated crossing points, are used to reduce speed, to prevent overtaking and generally contribute to a safer traffic situation. However, they might also cause increased response times for rescue vehicles (e.g. ambulances or fire trucks). An alternative to the conventional traffic calming measures is so-called smart traffic calming measures. These can determine when a vehicle approaches, whose journey should not be hindered, and adjust to allow for free passage for this vehicle.

    This report gives an overview of the problem, and some examples of smart  traffic calming measures are discussed. Special focus is put on the wireless communication necessary to detect emergency vehicles. Furthermore, existing challenges and possible solutions for traffic calming measures and the communication needed to make them smart are discussed.

  • 10.
    Alazawi, Salah
    et al.
    ISY, DATORSYSTEM, DI.
    Alilovic, Bojan
    ISY, DATORSSYTEM, DI.
    Konstruktion av Ethernet-baserad Qbussförlängare2008Independent thesis Basic level (degree of Bachelor), 10 points / 15 hpStudent thesis
    Abstract [sv]

     

    Syftet med var att konstruera ett bussförlängartkort till Qbussen som gör Ethernet-baserad kommunikation med I/O:t möjlig. Kortet ska kunna anslutas till standard 100 Mbits nätverksutrustning och klara autoförhandling och låsning av hastighet och duplex. Detta minskar på många ställen kabeldragningen väsentligt och det är därför önskvärt att SSAB:s egna I/O ska kunna köras så över Ethernet, antingen över vanliga nätverket eller på dedikerad kabel.

  • 11.
    Alfredsson, Erik
    Linköping University, Department of Electrical Engineering.
    Design and implementation of a hardware unit for complex division2005Independent thesis Basic level (professional degree), 20 points / 30 hpStudent thesis
    Abstract [en]

    The purpose of the thesis was to investigate and evaluate existing algorithms for division of complex numbers. The investigation should include implementation of a few suitable algorithms in VHDL. The main application for the divider is compensation for fading in a baseband processor.

    Since not much public research is done within the area of complex division in hardware, a divider based on real valued division was designed. The design only implements inversion of complex numbers instead of complete division because it is simpler and the application does not need full division, thus the required chip size is reduced.

    An examination of the different kinds of algorithms that exists for real valued division was done and two of the methods were found suitable for implementation, digit recurrence and functional iteration. From each of the two classes of algorithms one algorithm was chosen and implemented in VHDL. Two different versions of the inverter were designed for each method, one with full throughput and one with half throughput. The implementations show very similar results in terms of speed, size and performance. For most cases however, the digit recurrence implementation has a slight advantage.

  • 12.
    Alfredsson, Jonas
    Linköping University, Department of Electrical Engineering.
    Portning av ett plugin till 3d-modelleringsprogram2008Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    This report describes the work and the results found when comparing three different 3d modeler applications. The programs are 3ds Max, Maya and Cinema 4D. The comparisons focus on the possibilities/the amount of freedom these programs interface offer to its plugins. The comparisons are made from the point of view of a tool for creating animations developed as a plugin for these modelers. This plugins demands on the system it is loaded into have been analyzed and from the results of this analysis a template have been created. This template is to be used when porting the plugin to other modeler programs in order to be able to tell at an early stage if it’s possible, or not. This template is appended as an appendix. The plugin described above is in it self a system with a plugin architecture and is described on a higher level in the report.

  • 13.
    Ali Arslan, Mehmet
    et al.
    Lund University, Sweden.
    Gruian, Flavius
    Lund University, Sweden.
    Kuchcinski, Krzysztof
    Lund University, Sweden.
    Karlsson, Andreas
    Linköping University, Department of Electrical Engineering. Linköping University, Faculty of Science & Engineering.
    Code Generation for a SIMD Architecture with Custom Memory Organisation2016In: PROCEEDINGS OF THE 2016 CONFERENCE ON DESIGN AND ARCHITECTURES FOR SIGNAL and IMAGE PROCESSING, IEEE , 2016, p. 90-97Conference paper (Refereed)
    Abstract [en]

    Todays multimedia and DSP applications impose requirements on performance and power consumption that only custom processor architectures with SIMD capabilities can satisfy. However, the specific features of such architectures, including vector operations and high-bandwidth complex memory organization, make them notoriously complicated and time consuming to program. In this paper we present an automated code generation approach that dramatically reduces the effort of programming such architectures, by carrying out instruction scheduling and memory allocation based on a constraint programming formulation. Furthermore, the quality of the generated code is close to that of hand-written code by an experienced programmer with knowledge of the architecture. We demonstrate the viability of our approach on an existing custom heterogeneous DSP architecture, by compiling and running a number of typical DSP kernels, and comparing the results to hand-optimized code.

  • 14.
    Ali, Wajid
    et al.
    Linköping University, Department of Electrical Engineering, Information Coding. Linköping University, The Institute of Technology.
    Mohammed, Shahzaan
    Linköping University, Department of Electrical Engineering, Information Coding. Linköping University, The Institute of Technology.
    Analyzing Wavelength Conversion and Traffic Grooming in Optical WDM Networks2013Independent thesis Advanced level (degree of Master (One Year)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Wavelength conversion and traffic grooming have been among the most researched areas and technologies of importance in optical networking. Network performance improves significantly by relaxing the wavelength continuity constraint using wavelength converters and by improving the wavelength utilization using traffic grooming. We have done a literature review that compares the performance of wavelength conversion devices with different traffic grooming devices. This thesis work analyzes the impact of increasing the number of wavelength conversion devices and grooming capable devices using different placement schemes for our proposed network model, traffic loads and link capacities. Deciding the number and location of these devices to be used in a network is equally important. This work has been done through the simulation of different device placement scenarios and the results have been analyzed using connection blocking probability as the performance metric. Our reviews and work, correctly predict the behavior of results as demonstrated by the results of other referred literatures relating to wavelength conversion and traffic grooming.

  • 15.
    Allström, Andreas
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, Faculty of Science & Engineering.
    Highway Traffic State Estimation and Short-term Prediction2016Licentiate thesis, monograph (Other academic)
    Abstract [en]

    Traffic congestion is increasing in almost all large cities, leading to a number of negative effects such as pollution and delays. However, building new roads is not a feasible solution. Instead, the use of the existing road network has to be optimized, together with a shift towards more sustainable transport modes. In order to achieve this there are several challenges that needs to be addressed. One challenge is the ability to provide accurate information about the current and future traffic state. This information is an essential input to the traffic management center and can be used to influence the choices made by the travelers. Accurate information about the traffic state on highways, where the potential to manage and control the traffic in general is very high, would be of great significance for the traffic managers. It would help the traffic managers to take action before the system reaches congestion and limit the effects of it. At the same time, the collection of traffic data is slowly shifting from fixed sensors to more probe based data collection. This requires an adaptation and further development of the traditional traffic models in order for them to handle and take advantage of the characteristics of all types of data, not just data from the traditionally used fixed sensors.

    The objective of this thesis is to contribute to the development and implementation of a model for estimation and prediction of the current and future traffic state and to facilitate an adaptation of the model to the conditions of the highway in Stockholm. The model used is a version of the Cell Transmission Model (CTM-v) where the velocity is used as the state variable. Thus, together with an Ensemble Kalman Filter (EnKF) it can be used to fuse different types of point speed measurements. The model is developed to run in real-time for a large network. Furthermore, a two-stage process used to calibrate the model is implemented. The results from the calibration and validation show that once the model is calibrated, the estimated travel times corresponds well with the ground truth travel times collected from Bluetooth sensors.

    In order to produce accurate short-term predictions for various networks and conditions it is vital to combine different methods. We have implemented and evaluated a hybrid prediction approach that assimilates parametric and non-parametric short-term traffic state prediction. To predict mainline sensor data we use a neural network, while the CTM-v is ran forward in time in order to predict future traffic states. The results show that both the hybrid approach and the CTM-v prediction without the additional predicted mainline sensor data is superior to a naïve prediction method for longer prediction horizons.

  • 16.
    Almgren, Hanna
    et al.
    Linköping University, Department of Science and Technology.
    Vestin, Johanna
    Linköping University, Department of Science and Technology.
    Scalable Services over DAB and DVB-T from a Receiver Point of View2002Independent thesis Basic level (professional degree)Student thesis
    Abstract [en]

    TV and radio services have always been distributed over analogue broadcasting networks and been received on a TV -set or a radio receiver. Today this situation is changing due to digitalization and convergence between broadcasting, telecommunications and data communications. Other terminals, such as a PC, can also receive TV and radio services. Digital TV and radio can offer additional services such as e-commerce, electronic program guides and content synchronized to the TV and radio shows. If these services are to be received by several receiving terminals with different properties, the services must be adapted to the terminals. This can be done by scaling the services, meaning that the appearances and functionality of the services vary depending on the terminals’ properties. In this thesis scalable services are examined from a terminal point of view. Present and future receivers, platforms and possible methods to achieve scalability are presented, and their effects on scalable services are discussed.

  • 17.
    Aminifar, Amir
    et al.
    Linköping University, Department of Computer and Information Science, Software and Systems. Linköping University, Faculty of Science & Engineering.
    Bini, Enrico
    Scuola Super Sant Anna, Italy.
    Eles, Petru lon
    Linköping University, Department of Computer and Information Science, Software and Systems. Linköping University, Faculty of Science & Engineering.
    Peng, Zebo
    Linköping University, Department of Computer and Information Science, Software and Systems. Linköping University, Faculty of Science & Engineering.
    Analysis and Design of Real-Time Servers for Control Applications2016In: I.E.E.E. transactions on computers (Print), ISSN 0018-9340, E-ISSN 1557-9956, Vol. 65, no 3, p. 834-846Article in journal (Refereed)
    Abstract [en]

    Today, a considerable portion of embedded systems, e.g., automotive and avionic, comprise several control applications. Guaranteeing the stability of these control applications in embedded systems, or cyber-physical systems, is perhaps the most fundamental requirement while implementing such applications. This is different from the classical hard real-time systems where often the acceptance criterion is meeting the deadline. In other words, in the case of control applications, guaranteeing stability is considered to be a main design goal, which is linked to the amount of delay and jitter a control application can tolerate before instability. This advocates the need for new design and analysis techniques for embedded real-time systems running control applications. In this paper, the analysis and design of such systems considering a server-based resource reservation mechanism are addressed. The benefits of employing servers are manifold: providing a compositional and scalable framework, protection against other tasks misbehaviors, and systematic bandwidth assignment and co-design. We propose a methodology for designing bandwidth-optimal servers to stabilize control tasks. The pessimism involved in the proposed methodology is both discussed theoretically and evaluated experimentally.

  • 18.
    Amundin, Mats
    et al.
    Kolmården Wildlife Park.
    Hållsten, Henrik
    Filosofiska institutionen, Stockholms universitet.
    Eklund, Robert
    Linköping University, Department of Culture and Communication, Language and Culture. Linköping University, Faculty of Arts and Sciences.
    Karlgren, Jussi
    Kungliga Tekniska Högskolan.
    Molinder, Lars
    Carnegie Investment Bank, Swedden.
    A proposal to use distributional models to analyse dolphin vocalisation2017In: Proceedings of the 1st International Workshop on Vocal Interactivity in-and-between Humans, Animals and Robots, VIHAR 2017 / [ed] Angela Dassow, Ricard Marxer & Roger K. Moore, 2017, p. 31-32Conference paper (Refereed)
    Abstract [en]

    This paper gives a brief introduction to the starting points of an experimental project to study dolphin communicative behaviour using distributional semantics, with methods implemented for the large scale study of human language.

  • 19.
    Andell, Oscar
    et al.
    Linköping University, Department of Computer and Information Science.
    Andersson, Albin
    Linköping University, Department of Computer and Information Science.
    Slow rate denial of service attacks on dedicated- versus cloud based server solutions2018Independent thesis Basic level (degree of Bachelor), 10,5 credits / 16 HE creditsStudent thesis
    Abstract [en]

    Denial of Service (DoS) attacks remain a serious threat to internet stability. A specific kind of low bandwidth DoS attack, called a slow rate attack can with very limited resources potentially cause major interruptions to the availability of the attacked web servers. This thesis examines the impact of slow rate application layer DoS attacks against three different server solutions. The server solutions are a static cloud solution and a load-balancing cloud solution running on AmazonWeb Services (AWS) as well as a dedicated server. To identify the impact in terms of responsiveness and service availability a number of experiments were conducted on the web servers using publicly available DoS tools. The response times of the requests were measured. The results show that the dedicated and static cloud based server solutions are severely impacted by the attacks while the AWS load-balancing cloud solution is not impacted nearly as much. We concluded that all solutions were impacted by the attacks and that the readily available DoS tools are sufficient for creating a denial of service state on certain web servers.

  • 20.
    Andersson, Anders
    Linköping University, Department of Science and Technology.
    Gråbalans: i praktik och teori2003Independent thesis Basic level (professional degree)Student thesis
    Abstract [sv]

    Syfte

    Detta examensarbete gjordes för att försöka underlätta och förbättra arbetet med gråbalansstyrning vid dagstidningstryck. Punkter som ingår:

    - Hur väl går det att mäta med densitometer på gråbalansfälten, och vad kan påverka dess mätvärden?

    - Går det att hitta några riktlinjer för hur mätvärden, som erhålls från densitometern, skall förhålla sig till varandra?

    - Hur små kan gråbalansfälten vara och ändå vara tillförlitliga att arbeta med visuellt?

    - Hur förhåller sig konventionellt raster till stokastiskt raster?

    Resultat

    Vad gäller val av gråbalanston kan rekommenderas att använda någon av de fyra mellantoner, som ingick i undersökningen. Den allra ljusaste tonen i testerna är väldigt svår att läsa av visuellt, och vid mätning med densitometer är den inte tillräckligt känslig för variationer i fulltonsdensiteterna och punktareorna.Den allra mörkaste tonen är den som är enklast att läsa av visuellt i små fält, men vid mätning ger den väldigt spridda och oregelbundna mätvärden.

    Vid mätning med densitometer är konventionellt raster stabilare än stokastiskt raster. Stokastiskt raster ger lite högre mätvärden, än vad det konventionella rastret gör, då båda metoderna har samma rastertonvärden för de ingående tryckfärgerna. Vid visuell bedömning har rastermetoderna olika fördelar. För konventionellt raster är det lättare att identifiera små densitetsavvikelser, medan stokastiskt raster är lättare att avläsa på väldigt små fält, då avvikelsen på fulltonsdensiteten ligger på +/- 0,1 D.

    Placeringen på sidan spelar en stor roll när det gäller mätning med densitometer. Det allra viktigaste är att inte placera gråbalkarna så att de trycks bakom varandra på varsin sida av pappret. Detta påverkar mätningsresultatet relativt mycket. Även val av placering i tryckriktningen påverkar mätningar. Det gick att se klara tendenser på förändring i punktarean, genom att den ökade längs tryckriktningen. Denna förändring i punktarean påverkade mätvärdet.

    Vid mätning med densitometer på ett CMY-fält, tryckt med konventionellt raster, ska C och M ge samma värde, medan Y skall ligga ungefär 0,01 mätenhet högre. För att K-fältet ska vara så likt CMY-fältet som möjligt, bör dess K-värde ligga 0,02 mätenheter över värdet för C i CMY-fältet. Det inbördes förhållandet mellan C-, M- och Y-värdena i CMY-fälten är vid stokastiskt raster svårare att bestämma. De ligger dock nära varandra i de flesta toner. Som referensmätvärde för C kan sägas att det bör ligga något under tonvärdet för cyan, vid konventionellt raster. När stokastiskt raster används bör detta värde ligga något över tonvärdet för cyan.

  • 21.
    Andersson, Anders
    et al.
    Linköping University, Department of Electrical Engineering.
    Hallgren, Daniel
    Linköping University, Department of Electrical Engineering.
    Passive Aircraft Altimetry using GPS as a Bistatic Radar: A simulation model2003Independent thesis Basic level (professional degree)Student thesis
    Abstract [en]

    A common way to measure height in aerial vehicles is to use a radar height altimeter (RHM). Since the RHM transmits radar pulses that can be detected, a passive alternative would be desirable in military applications. The idea to use reflected signals from the Global Positioning System (GPS) as a bistatic radar, has been established over the last years. The GPS signals are already present and would not reveal aeroplanes in covert operations.

    In this thesis, the use of reflected GPS signals as a bistatic, passive altimeter is examined. A simulation model has been developed and implemented, and simulations using the model have been done. Different types of ground cover have been investigated, both water and land types, with varying reflectivity and scattering behaviour. For larger terrain variations, e.g. mountains and valleys, a ground elevation database has been used. Furthermore, several parameters, like the antenna coverage and the satellite elevation angle, have been varied and the result of this examined.

    The results of these simulations show that measuring height is possible for bothsea and land surfaces. The accuracy depends on several error factors, like a bias originating from surface roughness and measurement errors due to noise in the receiver. The simulations also show that the most important design parameter is the antenna, which must be designed to give a sufficiently large SNR, capture the specular reflection and avoid unwanted reflections.

  • 22.
    Andersson, Björn
    et al.
    Linköping University, Department of Science and Technology.
    Valfridsson, Martin
    Linköping University, Department of Science and Technology.
    Digital 3D Facial Reconstruction Based on Computed Tomography2005Independent thesis Basic level (professional degree)Student thesis
    Abstract [en]

    Despite the introduction of DNA-analysis for identification of human remains (1997-2000) several cases exist where the deceased remain unidentified. Approximately ten percent of unknown deceased persons can not be identified by dental status or other present methods. During the year 2003 alone, seven individuals, in Sweden, remain unidentified.

    Increase in travel in Europe will lead to more discoveries of foreign human remains in Sweden. In these cases, dental and medical records are often unavailable for the identification process. When reconstructing a face from a skull, a technique with so called landmarks is used. These landmarks define the distance between the skull and the skin.

    Today the reconstruction is performed by a forensic artist applying modelling clay to a cast of the skull according to the placement of the landmarks. This method is considered unethical since it involves manipulation of the skull. Another drawback with this method is that it is very time consuming and changes and modifications of the model are hard to do.

    This thesis presents the possibilities of digitally, in 3D, reconstructing deceased persons'faces based on computed tomography of skulls. This is done by presenting our PC based 3D modelling tool that we have implemented in Discreet 3ds max. By developing and testing our software we have shown that digital 3D facial reconstruction can be performed by acquiring data from CT and performing the reconstruction process in 3ds max withhelp from our software.

  • 23.
    Andersson, Daniel
    Linköping University, Department of Biomedical Engineering, Medical Informatics. Linköping University, The Institute of Technology.
    Automatic vertebrae detection and labeling in sagittal magnetic resonance images2015Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Radiologists are often plagued by limited time for completing their work, with an ever increasing workload. A picture archiving and communication system (PACS) is a platform for daily image reviewing that improves their work environment, and on that platform for example spinal MR images can be reviewed. When reviewing spinal images a radiologist wants vertebrae labels, and in Sectra's PACS platform there is a good opportunity for implementing an automatic method for spinal labeling. In this thesis a method for performing automatic spinal labeling, called a vertebrae classifier, is presented. This method should remove the need for radiologists to perform manual spine labeling, and could be implemented in Sectra's PACS software to improve radiologists overall work experience.Spine labeling is the process of marking vertebrae centres with a name on a spinal image. The method proposed in this thesis for performing that process was developed using a machine learning approach for vertebrae detection in sagittal MR images. The developed classifier works for both the lumbar and the cervical spine, but it is optimized for the lumbar spine. During the development three different methods for the purpose of vertebrae detection were evaluated. Detection is done on multiple sagittal slices. The output from the detection is then labeled using a pictorial structure based algorithm which uses a trained model of the spine to correctly assess correct labeling.

    The suggested method achieves 99.6% recall and 99.9% precision for the lumbar spine. The cervical spine achieves slightly worse performance, with 98.1% for both recall and precision. This result was achieved by training the proposed method on 43 images and validated with 89 images for the lumbar spine. The cervical spine was validated using 26 images. These results are promising, especially for the lumbar spine. However, further evaluation is needed to test the method in a clinical setting.

  • 24.
    Andersson, Lina
    Linköping University, Department of Science and Technology.
    Införande av ett dokumenthanteringssystem på SMHI2002Independent thesis Basic level (professional degree)Student thesis
    Abstract [sv]

    Den ostrukturerade dokumenthantering, som idag förekommer på avdelningen Ida på företaget SMHI, gav upphov till detta examensarbete.

    Ett dokumenthanteringssystem har införskaffats till avdelningen. Dokumenthanteringssystemet är en produkt från Microsoft med namnet SharePoint Portal Server (SPS), vilken levererats av WM-data. SPS är relativt ny på marknaden, vilket gör att erfarenheter saknas kring produkten.

    Syftet med dokumenthanteringssystemet är att samla alla dokument på samma plats, vilket gör dem lätt tillgängliga för alla berörda. Förhoppningsvis kommer införandet av ett dokumenthanteringssystem också att innebära att belastningen på övriga filtjänster minskar.

    Examensarbetet bestod i att göra ett förslag till både dokumentstruktur och metadata, som senare skulle implementeras i SPS.

    Dokumentstrukturen skapades med hänsyn till SMHI:s systemförvaltningsmodell. För att vara säker på att strukturen och metadatan skulle fungera i verkligheten, och inte bara på papperet, genomfördes två pilotsystem. Med hjälp av dessa gjordes några förändringar i både struktur och metadata.

    Dokumenthanteringssystemets alla funktioner har under examensarbetets gång utforskats med hjälp av manualer.Vilka dessa funktioner är och hur de fungerar beskrivs i denna rapport.

    Vid användandet av SPS har en hel del brister upptäckts i programvaran. Bristerna är av större eller mindre betydelse för SMHI:s behov. Dessa har dock anmälts till Microsoft, och man hoppas därmed att de blir åtgärdade till nästa version av SPS.

    Examensarbetet har resulterat i ett förslag till dokumentstruktur och ett förslag till metadata. Förslagen implementerades också i dokumenthanteringssystemet, eftersom tiden medgav detta.

  • 25.
    Andersson, Magnus
    et al.
    Linköping University, Department of Electrical Engineering.
    Severinson, Kristofer
    Linköping University, Department of Electrical Engineering.
    Hydroakustisk kommunikation med bandspridningsteknik2004Independent thesis Basic level (professional degree)Student thesis
    Abstract [en]

    This thesis investigates techniques for stealth hydroacoustic communication using spread spectrum. The Swedish naval defense organisations have a vision that all their units should be able to communicate with each other, even between underwater vehicles. But the properties of water makes it a complex channel to use for wireless communications. Radiomagnetic waves have very limited range in water, therefore acoustic waves are used.

    In this report the basics of wireless communication systems are described including source coding, channel coding, modulation techniques as well as different techniques for spread spectrum. The fundamental principle for all spread spectrum systems is to use more bandwidth than necessary to spread the signal energy in the frequency spectrum. This limits the data rate but results in a robust communication link which is difficult to detect, intercept and to jam.

    In addition to the theoretical background, this thesis also gives a brief description of a Matlab system and a VHDL-system that was developed during the project. Finally the results of this project are presented and some suggestions of further developments are given.

  • 26.
    Andersson, Marcus
    Linköping University, Department of Science and Technology.
    Cryptographic Key Masking During Run-Time2008Independent thesis Basic level (professional degree), 20 points / 30 hpStudent thesis
    Abstract [en]

    Many of the products commercially available today contain some form of encrypted or hashed data. It can involve DRM protection, licenses and certificates, signatures or identification information. Regardless of what the data is intended for, it is protected for a reason and may be worth a great deal of money to the owner.

    There are numerous examples of products that have been subject to hacking in the form of simple memory attacks. If the keys are made all too easily extracted, the value of the protected data will soon be lost.

    The aim of the thesis work discussed in this report was to evaluate the vulnerabilities in mobile phones to this sort of attacks and to find possible security enhancements that can be applied. A method is proposed where masking will secure the cryptology keys while they reside in the memory.

    Different masks are developed and tested - The effects on performance are measured and the security is evaluated.

    The thesis work concludes that it is possible to implement masking on many of the security functions using keys and that the masks will increase security. The conclusion also states that the time consumption of the masking heavily depends on which mask that is used and that the masking could be applied in such a way that the level of masking can be varied.

  • 27.
    Andersson, Mikael
    et al.
    Linköping University, Department of Electrical Engineering.
    Karlström, Per
    Linköping University, Department of Electrical Engineering.
    Parallel JPEG Processing with a Hardware Accelerated DSP Processor2004Independent thesis Basic level (professional degree)Student thesis
    Abstract [en]

    This thesis describes the design of fast JPEG processing accelerators for a DSP processor.

    Certain computation tasks are moved from the DSP processor to hardware accelerators. The accelerators are slave co processing machines and are controlled via a new instruction set. The clock cycle and power consumption is reduced by utilizing the custom built hardware. The hardware can perform the tasks in fewer clock cycles and several tasks can run in parallel. This will reduce the total number of clock cycles needed.

    First a decoder and an encoder were implemented in DSP assembler. The cycle consumption of the parts was measured and from this the hardware/software partitioning was done. Behavioral models of the accelerators were then written in C++ and the assembly code was modified to work with the new hardware. Finally, the accelerators were implemented using Verilog.

    Extension of the accelerator instructions was given following a custom design flow.

  • 28.
    Andersson, Olof
    et al.
    Linköping University, Department of Electrical Engineering, Computer Engineering.
    Bengtsson, Karl
    Linköping University, Department of Electrical Engineering, Computer Engineering.
    Adapting an FPGA-optimized  microprocessor to the MIPS32 instruction set2010Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Nowadays, FPGAs are large enough to host entire system-on-chip designs, wherein a soft core processor is often an integral part. High performance of the processor is always desirable, so there is an interest in finding faster solutions.This report aims to describe the work and results performed by Karl Bengtson and Olof Andersson at ISY. The task was to continue the development of a soft core microprocessor, originally created by Andreas Ehliar. The first step was to decide a more widely adopted instruction set for the processor. The choice fell upon the MIPS32 instruction set. The main work of the project has been focused on implementing support for MIPS32, allowing the processor to execute MIPS assembly language programs. The development has been done with speed optimization in mind. For every new function, the effects on the maximum frequency has been considered, and solutions not satisfying the speed requirements has been abandoned or revised.The performance has been measured by running a benchmark program—Coremark. Comparison has also been made to the main competitors among soft core processors. The results were positive, and reported a higher Coremark score than the other processors inthe study. The processor described herein still lacks many essential features. Nevertheless, the conclusion is that it may be possible to create a competitive alternative to established soft processors.

  • 29.
    Andersson, Patrik
    et al.
    Linköping University, Department of Computer and Information Science. Linköping University, Faculty of Science & Engineering.
    Berntsen, David
    Linköping University, Department of Computer and Information Science. Linköping University, Faculty of Science & Engineering.
    Hultqvist, Tobias
    Linköping University, Department of Computer and Information Science. Linköping University, Faculty of Science & Engineering.
    Post, Jesper
    Linköping University, Faculty of Science & Engineering. Linköping University, Department of Computer and Information Science.
    Schlyter, Fredrik
    Linköping University, Faculty of Science & Engineering. Linköping University, Department of Computer and Information Science.
    Sibelius Parmbäck, Sebastian
    Linköping University, Faculty of Science & Engineering. Linköping University, Department of Computer and Information Science.
    Therén, Oskar
    Linköping University, Faculty of Science & Engineering. Linköping University, Department of Computer and Information Science.
    Iterativ utveckling av en adaptiv bildvisare för mobila plattformar2015Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [sv]

    Detta dokument behandlar ett kandidatarbete gjort av sju datateknikstudenter från Tekniska högskolan vid Linköpings universitet. Arbetet gick ut på att utveckla en webbapplikation för att visa bilder. Målet med webbapplikationen var inledningsvis vagt, den skulle visa bilder, ha någon metod för att ta reda på vilka bilder användaren gillade och sedan basera vilka bilder som skulle visas nästa gång på vilka som hade gillats.

    Dokumentet innehåller också ett kapitel om de erfarenheter och lärdomar gruppen har fått från projektet. Det innehåller även ett appendix med kapitel skrivna av gruppens medlemmar som behandlar olika ämnen relevanta till arbetet.

  • 30.
    Andersson, Robin
    Linköping University, Department of Computer and Information Science, Human-Centered systems.
    Utveckling av tvådimensionellt online-spel i kategorin action-strategi för smartphones med fokus på spelupplevelse och prestanda2017Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [sv]

    Vid utveckling av spel till smartphones så krävs ofta flera olika implementationer för olika plattformar. Men det finns olika spelmotorer och ramverk till olika programspråk som kan kompilera samma kod till flera olika mobila plattformar. Kivy är ett sådant ramverk för programspråket Python.

    I detta arbete användes prototypdriven utveckling i Kivy för att försöka höja spelupplevelsen av ett tvådimensionellt online-spel i kategorin action-strategi som tidigare fanns implementerat i GameMaker. Olika tekniker för att öka prestandan för spelet testades också. Det visade sig att med den bästa kombinationen av de tekniker som testades så blev prestandan med hög last cirka 29 bilder/s. Användarbarheten, spelbarheten och ljud-estetiken av spelet ökades medan nöjet och den personliga tillfredställelsen från spelet minskade. Totalt sett blev spelupplevelsen i stort sätt oförändrad.

  • 31.
    Andin, Karl
    et al.
    Linköping University, Department of Computer and Information Science, Human-Centered systems. Linköping University, The Institute of Technology.
    Ahl, Andreas
    Linköping University, Department of Computer and Information Science, Human-Centered systems. Linköping University, The Institute of Technology.
    Mobile application for speech quality measurement2012Independent thesis Basic level (degree of Bachelor), 10,5 credits / 16 HE creditsStudent thesis
    Abstract [en]

    This report describes a bachelor thesis in computer science performed at the system department within the product development unit for GSM (Global System for Mobile communication) at Ericsson in Linköping.GSM can be considered a mature technology but it is still updated with new features on a regular basis. This requires that the technology also continuously is being tested. One technique that is used to perform quality tests is called PESQ (Perceptual Evaluation of Speech Quality). PESQ is a standardized algorithm to perform speech quality tests; it gives a score based on how a human would percept speech quality.The purpose of this thesis was to enhance the speech quality analysis process used when testing the GSM network. One goal was to analyze if it was possible to record and inject sound into a phone call and verify the possibility to execute the PESQ algorithm using a smartphone. Another goal was to develop a smartphone application to perform the described tasks.In order to do so an application for Android was developed. The development process included an investigation whether the Android platform supplies the functionality required. The investiga-tion showed that no general solution for recording and injecting audio into a phone call could be found. Recording was possible on some smartphones, but the characteristics of the recorded audio were not as desired. No solution for injecting audio into a phone call could be found for any of the tested smartphones.However, even though no solution for recording and injecting was found, an application was developed. The application was decided to be more of a proof of concept on how an application of this kind would work. It would also be a good foundation for future development. Suggested future work in order to integrate the application into the existing testing environment is to find alternative solutions for recording and injecting, maybe with the help of smartphone manu-facturers.

  • 32.
    Andreasson, Robert
    Linköping University, Department of Electrical Engineering, Computer Engineering.
    Design of an FPGA Based JTAG Recorder for use in Production of IPTV Set-Top Boxes2009Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    This thesis evaluates the possibility to replace the manufacturer dependent JTAG device used in the production tests of IPTV set-top boxes for storing the boot loader in the main memory in order to start the box for the first time. An FPGA based prototype was built in order to see if it is possible to record the JTAG signals, to an external DDR SDRAM, without understanding them and be able to perform a delayed playback resulting in the same bahavoir as with the original JTAG device.Overall the thesis was succesful and it shows that it is infact feasible to create a JTAG recorder based on an FPGA. A lot of data is used for storing the sequence though so the use of a fast memory is cruicial. However in this thesis the speed of both the recording and the delayed playback was reduced in order to work properly.

  • 33.
    Antonsson, Daniel
    Linköping University, Department of Electrical Engineering.
    A server application for Traffic Information Service: Broadcast2003Independent thesis Basic level (professional degree)Student thesis
    Abstract [en]

    The need for increased safety and efficiency in civil aviation is pushing the introduction of Automatic Dependent Surveillance - Broadcast (ADS-B). The basic principle of ADS-B is that each aircraft is able to communicate its position and status over a radio data link to surrounding aircraft. In this way each aircraft obtains a detailed picture of the surrounding traffic. During a period of transition from today's radar surveillance to ADS-B many aircraft will not be equipped with the new data link technology and will therefore be invisible to the ADS-B equipped aircraft. The Traffic Information Service - Broadcast (TIS-B) has been conceived to be the solution to this problem. TIS-B is defined as a broadcast surveillance service in which data from the ordinary ground radar system is transmitted from a ground station to airborne systems, providing an air situation picture of the non-ADS-B stations.

    The topics of this thesis are the definition and implementation of a TIS-B server. The presented solution is an evaluation TIS-B server that will receive data from a data-fusing tracker and provide one or several TIS-B ground stations with data filtered according to the settings of the server.

  • 34.
    Arbring, Joel
    et al.
    Linköping University, Department of Electrical Engineering, Information Coding.
    Hedström, Patrik
    Linköping University, Department of Electrical Engineering, Information Coding.
    On Data Compression for TDOA Localization2010Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    This master thesis investigates different approaches to data compression on common types of signals in the context of localization by estimating time difference of arrival (TDOA). The thesis includes evaluation of the compression schemes using recorded data, collected as part of the thesis work. This evaluation shows that compression is possible while preserving localization accuracy.

    The recorded data is backed up with more extensive simulations using a free space propagation model without attenuation. The signals investigated are flat spectrum signals, signals using phase-shift keying and single side band speech signals. Signals with low bandwidth are given precedence over high bandwidth signals, since they require more data in order to get an accurate localization estimate.

    The compression methods used are transform based schemes. The transforms utilized are the Karhunen-Loéve transform and the discrete Fourier transform. Different approaches for quantization of the transform components are examined, one of them being zonal sampling.

    Localization is performed in the Fourier domain by calculating the steered response power from the cross-spectral density matrix. The simulations are performed in Matlab using three recording nodes in a symmetrical geometry.

    The performance of localization accuracy is compared with the Cramér-Rao bound for flat spectrum signals using the standard deviation of the localization error from the compressed signals.

  • 35.
    Areström, Erik
    Linköping University, Department of Computer and Information Science.
    Flow Classification of Encrypted Traffic Streams using Multi-fractal Features2018Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The increased usage of encrypted application layer traffic is making it harder for traditional traffic categorization methods like deep packet inspection to function. Without ways of categorizing traffic, network service providers have a hard time optimizing traffic flows, resulting in worse quality of experience for the end user. Recent solutions to this problem typically apply some statistical measurements on network flows and use the resulting values as features in a machine learning model. However, by utilizing recent advances in multi-fractal analysis, multi-fractal features can be extracted from time-series via wavelet leaders, which can be used as features instead. In this thesis, these features are used exclusively, together with support vector machines, to build a model that categorizes encrypted network traffic into six categories that, according to a report, accounts for over 80% of the mobile traffic composition. The resulting model achieved a F1-score of 0.958 on synthetic traffic while only using multi-fractal features, leading to the conclusion that incorporating multi-fractal features in a traffic categorization framework, implemented at a base station, would be beneficial for the categorization score for such a framework.

  • 36.
    Arvid, Johnsson
    Linköping University, Department of Computer and Information Science, Software and Systems.
    Analysis of GPU accelerated OpenCL applications on the Intel HD 4600 GPU2017Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    GPU acceleration is the concept of accelerating the execution speed of an application by running it on the GPU. Researchers and developers have always wanted to achieve greater speed for their applications and GPU acceleration is a very common way of doing so. This has been done a long time for highly graphical applications using powerful dedicated GPUs. However, researchers have become more and more interested in using GPU acceleration on everyday applications. Moreover now a days more or less every computer has some sort of integrated GPU which often is underutilized. The integrated GPUs are not as powerful as dedicated ones but they have other benefits such as a lower power consumption and faster data transfer. Therefore this thesis’ purpose was to examine whether the integrated GPU Intel HD 4600 can be used to accelerate the two applications Image Convolution and sparse matrix vector multiplication (SpMV). This was done by analysing the code from a previous thesis which produced some unexpected results as well as a benchmark from the OpenDwarf’s benchmark suite. The Intel HD 4600 was able to speedup both Image Convolution and SpMV by about two times compared to running them on the Intel i7-4790. However, the SpMV implementation was not well suited for the GPU meaning that the speedup was only observed on ideal input configurations.

  • 37.
    Asghar, Syed Adeel
    et al.
    Linköping University, Department of Computer and Information Science, PELAB - Programming Environment Laboratory.
    Tariq, Sonia
    Linköping University, Department of Computer and Information Science, PELAB - Programming Environment Laboratory.
    Design and Implementation of a User Friendly OpenModelica Graphical Connection Editor2010Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    OpenModelica (www.openmodelica.org) is an open-source Modelica-based modeling and simulation environment intended for industrial as well as academic usage. Its long-term development is supported by a non-profit organization – the Open Source Modelica Consortium OSMC, where Linköping University is a member.The main reason behind this thesis was the need for a user friendly, efficient and modular OpenModelica graphical connection editor. The already existing open source editors were either textual or not so user friendly. As a part of this thesis work a new open source Qt-based cross platform graphical user interface was designed and implemented, called OMEdit, partially based on an existing GUI for hydraulic systems, HOPSAN. The usage of Qt C++ libraries makes this tool more future safe and also allows it to be easily integrated into other parts of the OpenModelica platform.This thesis aims at developing an advanced open source user friendly graphical user interface that provides the users with easy-to-use model creation, connection editing, simulation of models, and plotting of results. The interface is extensible enough to support user-defined extensions/models. Models can be both textual and graphical. From the annotation information in the Modelica models (e.g. Modelica Standard Library components) a connection tree and diagrams can be created. The communication to the OpenModelica Compiler (OMC) Subsystem is performed through a Corba client-server interface. The OMC Corba server provides an interactive API interface. The connection editor will function as the front-end and OMC as the backend. OMEdit communicates with OMC through the interactive API interface, requests the model information and creates models/connection diagrams based on the Modelica annotations standard version 3.2.

  • 38.
    Asif, Shahzad
    et al.
    Western Sydney Univ, Australia.
    Vesterbacka, Mark
    Linköping University, Department of Electrical Engineering, Integrated Circuits and Systems. Linköping University, Faculty of Science & Engineering.
    An RNS Based Modular Multiplier with Reduced Complexity2017In: 2017 IEEE NORDIC CIRCUITS AND SYSTEMS CONFERENCE (NORCAS): NORCHIP AND INTERNATIONAL SYMPOSIUM OF SYSTEM-ON-CHIP (SOC), IEEE , 2017Conference paper (Refereed)
    Abstract [en]

    Modular multiplication (MM) based on the residue number system (RNS) is a widely researched area due to the fast arithmetic operations in the RNS. The major drawback of the RNS based MM architectures is their large area because each arithmetic operation is followed by a modular reduction. In this work, the number of modular reductions is reduced and instead the wordlength of some operations is increased to accommodate the intermediate results. The proposed scheme greatly reduces the number of multipliers and achieves a 55% reduction in the hardware complexity. Moreover the delay of the proposed architecture is also significantly lower than the reference architecture.

  • 39.
    Avdic, Kenan
    Linköping University, Department of Computer and Information Science, Software and Systems. Linköping University, The Institute of Technology.
    On-chip Pipelined Parallel Mergesort on the Intel Single-Chip Cloud Computer2014Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    With the advent of mass-market consumer multicore processors, the growing trend in the consumer off-the-shelf general purpose processor industry has moved away from increasing clock frequency as the classical approach for achieving higher performance. This is commonly attributed to the well-known problems of power consumption and heat dissipation with high frequencies and voltage.

    This paradigm shift has prompted research into a relatively new field of "many-core" processors, such as the Intel Single-chip Cloud Computer. The SCC is a concept vehicle, an experimental homogenous architecture employing 48 IA32 cores interconnected by a high-speed communication network.

    As similar multiprocessor systems, such as the Cell Broadband Engine, demonstrate a significantly higher aggregate bandwidth in the interconnect network than in memory, we examine the viability of a pipelined approach to sorting on the Intel SCC. By tailoring an algorithm to the architecture, we investigate whether this is also the case with the SCC and whether employing a pipelining technique alleviates the classical memory bottleneck problem or provides any performance benefits.

    For this purpose, we employ and combine different classic algorithms, most significantly, parallel mergesort and samplesort.

  • 40.
    Avgouleas, Ioannis
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, Faculty of Science & Engineering.
    IoT Networking Resource Allocation and Cooperation2017Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    The Internet of Things (IoT) promises that "anything that can be connected, will be connected". It comprises of Information and Communication Technologies that interconnect billions of physical and visual things with some "basic" intelligence. The emerging IoT services will be able to react with minimal human intervention and further contribute to the big data era that requires real-time, ultrareliable, ubiquitous, scalable, and heterogeneous operation.

    This thesis is the result of our investigations on problems dealing with the evolution of such technologies. First, we explore the potential of using relay i.e., intermediate, nodes that assist users to transmit their packets in a a cellular network. Paper I provides insights into how adapting the cooperation of the relay's receiver and transmitter optimizes the network-wide throughput while the relay's queue stability is guaranteed.

    The next part of the thesis copes with the resource allocation of services on IoT devices equipped with multiple network interfaces. The resources are heterogeneous and can be split among dierent interfaces. Additionally, they are not interchangeable. In paper II, we develop optimization models for this resource allocation problem, prove the complexity of the models, and derive results that give intuition into the problems. Moreover, we propose algorithms that approximate the optimal solution and show under which circumstances this is possible.

    Finally, in paper III, we present a resource allocation problem specically for smart cities services. In comparison to the previous problem denition, resources are of one type but the IoT network device can oer capacities that vary over time. Furthermore, services have a tolerance regarding their preferred scheduling, namely, their allocation over time. We parametrize each service with a pricing function to indicate its tolerance to be served at the beginning of the scheduling window. We prove that the problem is computationally hard and provide numerical results to gain insight into how different pricing weight functions impact the allocations' distribution within the scheduling window.

    List of papers
    1. Probabilistic Cooperation of a Full-Duplex Relay in Random Access Networks
    Open this publication in new window or tab >>Probabilistic Cooperation of a Full-Duplex Relay in Random Access Networks
    2017 (English)In: IEEE Access, E-ISSN 2169-3536, Vol. 5, p. 7394-7404Article in journal (Refereed) Published
    Abstract [en]

    In this paper, we analyze the probabilistic cooperation of a full-duplex relay in a multiuser random-access network. The relay is equipped with on/off modes for the receiver and the transmitter independently. These modes are modeled as probabilities by which the receiver and the transmitter are activated. We provide analytical expressions for the performance of the relay queue, such as arrival and service rates, stability conditions, and the average queue size. We optimize the relays operation setup to maximize the network-wide throughput while, simultaneously, we keep the relays queue stable and lower the relays receptions and transmissions. Furthermore, we study the effect of the SINR threshold and the self-interference coefficient on the per-user and network-wide throughput. For low SINR threshold, we show under which circumstances it is beneficial to switch off the relay completely, or switch off the relays receiver only.

    Place, publisher, year, edition, pages
    IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC, 2017
    Keywords
    Cooperative communication; relays; relay networks; multiaccess communication; multiple access interference; internet of things (IoT); internet; wireless sensor networks (WSNs); body sensor networks (BSNs)
    National Category
    Computer Systems
    Identifiers
    urn:nbn:se:liu:diva-139423 (URN)10.1109/ACCESS.2016.2642540 (DOI)000403140800053 ()
    Note

    Funding Agencies|European Union [609094, 612361]

    Available from: 2017-08-07 Created: 2017-08-07 Last updated: 2018-05-14
    2. Allocation of Heterogeneous Resources of an IoT Device to Flexible Services
    Open this publication in new window or tab >>Allocation of Heterogeneous Resources of an IoT Device to Flexible Services
    Show others...
    2016 (English)In: IEEE Internet of Things Journal, ISSN 2327-4662, Vol. 3, no 5, p. 691-700Article in journal (Refereed) Published
    Abstract [en]

    Internet-of-Things (IoT) devices can be equipped with multiple heterogeneous network interfaces. An overwhelmingly large amount of services may demand some or all of these interfaces available resources. Herein, we present a precise mathematical formulation of assigning services to interfaces with heterogeneous resources in one or more rounds. For reasonable instance sizes, the presented formulation produces optimal solutions for this computationally hard problem. We prove the NP-completeness of the problem and develop two algorithms to approximate the optimal solution for big instance sizes. The first algorithm allocates the most demanding service requirements first, considering the average cost of interfaces resources. The second one calculates the demanding resource shares and allocates the most demanding of them first by choosing randomly among equally demanding shares. Finally, we provide simulation results giving insight into services splitting over different interfaces for both cases.

    Place, publisher, year, edition, pages
    Institute of Electrical and Electronics Engineers (IEEE), 2016
    Keywords
    Internet of Things (IoT); mixed integer linear programming; network interfaces; optimization; resource management; scheduling algorithms
    National Category
    Communication Systems
    Identifiers
    urn:nbn:se:liu:diva-135000 (URN)10.1109/JIOT.2016.2535163 (DOI)000393047800006 ()
    Note

    Funding Agencies|Excellence Center at Linkoping-Lund in Information Technology; European Union [324515, 612316, 609094]

    Available from: 2017-03-06 Created: 2017-03-06 Last updated: 2017-08-21Bibliographically approved
  • 41.
    Axell, Christian
    et al.
    Linköping University, Department of Electrical Engineering.
    Brogsten, Mikael
    Linköping University, Department of Electrical Engineering.
    Efficient WiMAX Receiver Implementation on a Programmable Baseband Processor2006Independent thesis Basic level (professional degree), 20 points / 30 hpStudent thesis
    Abstract [en]

    WiMAX provides broadband wireless access and uses OFDM as the underlying modulation technique. In an OFDM based wireless communication system, the channel will distort the transmitted signal and the performance is seriously degraded by synchronization mismatches between the transmitter and receiver. Therefore such systems require extensive digital signal processing of the received signal for retrieval of the transmitted information.

    In this master thesis, parts of an IEEE 802.16d (WiMAX) receiver have been implemented on a programmable baseband processor. The implemented parts constitute baseband algorithms which compensates for the effects from the channel and synchronization errors. The processor has a new innovative architecture with an instruction set optimized for baseband applications.

    This report includes theory behind the baseband algorithms as well as a presentation of how they are implemented on the processor. An impartial evaluation of the processor performance with respect to the algorithms used in the reference model is also presented in the report.

  • 42.
    Axelson, Per-Erik
    Linköping University, Department of Science and Technology.
    Quality Measures of Halftoned Images (A Review)2003Independent thesis Basic level (professional degree)Student thesis
    Abstract [en]

    This study is a thesis for the Master of Science degree in Media Technology and Engineering at the Department of Science and Technology, Linkoping University. It was accomplished from November 2002 to May 2003.

    Objective image quality measures play an important role in various image processing applications. In this paper quality measures applied on halftoned images are aimed to be in focus. Digital halftoning is the process of generating a pattern of binary pixels that create the illusion of a continuous- tone image. Algorithms built on this technique produce results of very different quality and characteristics. To evaluate and improve their performance, it is important to have robust and reliable image quality measures. This literature survey is to give a general description in digital halftoning and halftone image quality methods.

  • 43.
    Axelsson, Alfred
    Linköping University, Department of Computer and Information Science, Human-Centered systems.
    Designing for usability of 3D configuration in E-commerce: Interactive design of 3D in web applications2017Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Mass production of consumer products is both wasteful and limit the consumers' power to influence the design of what they are buying. When shopping for a product, the customer must choose between a range of specific products with limited variations. What if the customer could make all the design choices, creating and buying the product according to his or her own needs?

    A 3D product generator holding a configurable model of a product was created to replace static content in online stores and give creative power to customers. This work aimed at creating an effective 3D product generator by evaluating how users experience the design of and interaction with it, and finding general design goals when introducing interactive 3D content in static 2D environments.

    A prototype of a 3D product generator in a generic online storefront was implemented in two iterations, improving on and evaluating the design through usability testing. The evaluation of the final prototype suggested that the interface was indeed effective in both design and interaction. This work concludes that user feedback is crucial to creating a successful user experience, which in turn is important when creating interfaces for product configuration.

  • 44.
    Axelsson, Victor
    et al.
    Linköping University, Department of Computer and Information Science.
    Bucht, Sebastian
    Linköping University, Department of Computer and Information Science.
    Hellmark Carrasco, Michelle
    Linköping University, Department of Computer and Information Science.
    Fridell, Gustav
    Linköping University, Department of Computer and Information Science.
    Hagel, Sofia
    Linköping University, Department of Computer and Information Science.
    Larsson, Pontus
    Linköping University, Department of Computer and Information Science.
    Olaussen, Jonas
    Linköping University, Department of Computer and Information Science.
    Ståhl, Erik
    Linköping University, Department of Computer and Information Science.
    ITREA – Utveckling av framtidens digitala annonseringsplats2018Independent thesis Basic level (degree of Bachelor), 12 credits / 18 HE creditsStudent thesis
    Abstract [en]

    This study has investigated the development of a web application in the form of a digital marketplace for IT services. The problem statement addresses how a web application of this kind can be designed to achieve three criteria; high usability, good user experience and high credibility. These factors are important to attract users to the web application, and in this way connect contractors and outsourcers for IT services. The web application has been tested iteratively during the development process to corroborate whether the implementation achieves the three criteria. This process has led to a final result of a web application that, according to performed tests, meets these criteria. A high navigability on the web application has been achieved through implementing a layout based on the four primary objectives of navigability and on a distinct connection between all pages. Furthermore, the web application’s readability has been developed with a distinct vocabulary and a font adapted to the operating system and unit the web application is run on. An appealing design has been formed through implementing a layout with color selection based on theory, that strengthens the user’s impression of the application. A responsive design has been implemented by having both a well-adapted layout and appropriate content. The web application’s high credibility has been formed by forging the application based on the seven guidelines for credibility. The conclusion drawn is that the method that has been presented is applicable to achieve the three criteria; usability, user experience and credibility. This conclusion does not only apply to web applications in the form of digital marketplaces, but also to web applications in general. 

  • 45.
    Axholt, Magnus
    et al.
    Linköping University, Department of Science and Technology.
    Peterson, Stephen
    Linköping University, Department of Science and Technology.
    Modelling Traffic Scenarios for Realistic Air Traffic Control Environment Testing2004Independent thesis Basic level (professional degree)Student thesis
    Abstract [en]

    As air traffic is forecasted to increase, air traffic control software subsequently needs to be more sophisticated. To efficiently push development forward, testing is important in order to determine usability. The tests need to be adapted to fit a particular purpose and carried out with methods that preserve the validity of the results.

    This thesis describes an implementation project carried out at the EUROCONTROL Experimental Centre, Bretigny-sur-Orge, France. The purpose of the project is to create an application that enables a user to create datasets of air traffic to be used for these tests. The application allows for manual work or bulk imports from external data sources. Furthermore it compiles scenarios as output datasets intended for prototype air traffic control software developed at Linköping University.

    The application design rationale and development process is described. Some time is spent on demonstrating the flexibility of the application and how its usage fits in a bigger picture.

  • 46.
    Axholt, Magnus
    et al.
    Linköping University, Department of Science and Technology, Visual Information Technology and Applications (VITA). Linköping University, The Institute of Technology.
    Peterson, Stephen D.
    Linköping University, Department of Science and Technology, Visual Information Technology and Applications (VITA). Linköping University, The Institute of Technology.
    Ellis, Stephen R.
    NASA Ames Research Center.
    Visual Alignment Accuracy in Head Mounted Optical See-Through AR Displays: Distribution of Head Orientation Noise2009In: Proceedings of the Human Factors and Ergonomics Society 53rd Annual Meeting 2009, San Antonio (TX), USA: Human Factors and Ergonomics Society , 2009, p. 2024-2028Conference paper (Refereed)
    Abstract [en]

    The mitigation of registration errors is a central challenge for improving the usability of AugmentedReality systems. While the technical achievements within tracking and display technology continue toimprove the conditions for good registration, little research is directed towards understanding theuser’s visual alignment performance during the calibration process. This paper reports 12 standingsubjects’ visual alignment performance using an optical see-through head mounted display for viewingdirections varied in azimuth (0°, ±30°, ±60°) and elevation (0°, ±10°). Although viewing direction hasa statistically significant effect on the shape of the distribution, the effect is small and negligible forpractical purposes and can be approximated to a circular distribution with a standard deviation of 0.2°for all viewing directions studied in this paper. In addition to quantifying head aiming accuracy with ahead fixed cursor and illustrating the deteriorating accuracy of boresight calibration with increasingviewing direction extremity, the results are applicable for filter design determining the onset and end ofhead rotation.

  • 47.
    Axholt, Magnus
    et al.
    Linköping University, Department of Science and Technology, Visual Information Technology and Applications (VITA). Linköping University, The Institute of Technology.
    Peterson, Stephen D.
    Linköping University, Department of Science and Technology, Visual Information Technology and Applications (VITA). Linköping University, The Institute of Technology.
    Ellis, Stephen R.
    NASA Ames Research Center.
    Visual Alignment Precision in Optical See - Through AR Displays: Implications for Potential Accuracy2009In: Proceedings of the ACM/IEEE Virtual Reality International Conference, Association for Computing Machinery (ACM), 2009Conference paper (Other academic)
    Abstract [en]

    The quality of visual registration achievable with anoptical see-through head mounted display (HMD)ultimately depends on the user’s targetingprecision. This paper presents design guidelines forcalibration procedures based on measurements ofusers’ head stability during visual alignment withreference targets. Targeting data was collected from12 standing subjects who aligned a head fixedcursor presented in a see-through HMD withbackground targets that varied in azimuth (0°, ±30°,±60°) and elevation (0°, ±10°). Their data showedthat: 1) Both position and orientation data will needto be used to establish calibrations based on nearbyreference targets since eliminating body swayeffects can improve calibration precision by a factorof 16 and eliminate apparent angular anisotropies.2) Compensation for body sway can speed thecalibration by removing the need to wait for thebody sway to abate, and 3) calibration precision canbe less than 2 arcmin even for head directionsrotated up to 60° with respect to the user’s torsoprovided body sway is corrected. Users ofAugmented Reality (AR) applications overlookinglarge distances may avoid the need to correct forbody sway by boresighting on markers at relativelylong distances, >> 10 m. These recommendationscontrast with those for heads up displays using realimages as discussed in previous papers.

  • 48.
    Axling, LIsa
    et al.
    Linköping University, Department of Science and Technology.
    Hellström, Frida
    Linköping University, Department of Science and Technology.
    Trådlöst nätverk: En förstudie vid Campus Norrköping2002Independent thesis Basic level (professional degree)Student thesis
    Abstract [sv]

    Syftet med denna rapport är att göra en förstudie vid campus Norrköping rörande trådlöst nätverk. Det finns många olika standarder och tekniker. Vi har valt att rikta in oss på 802.11b då det är den som används mest. Trådlösa nätverk är ett bra komplement till vanliga kabelburna nätverk då det är flexibelt, relativt billigt och lätt att installera. Användningsområden för denna typ av nätverk är bland annat företag, hemmamiljö och allmänna platser såsom hotell och flygplatser, där människor kan förvandla improduktiv väntetid till effektiv arbetstid.

    Vi ville undersöka hur förhållandet för trådlöst nätverk på plan fyra och fem i Täppan är. Detta gjorde vi genom att sätta upp basstationer av två olika märken på varierade platser på de olika planen samt göra de mätningar som vi ansåg nödvändiga. Vi tillämpande inte några av de säkerhetsföreskrifter som finns då det inte var syftet med studien, men säkerhet är ändå en av tyngdpunkterna i vår teoretiska del av rapporten. Med hjälp av den praktiska tillämpningen och våra kunskaper kunde vi dra slutsatsen att det skulle fungera bra att tillämpa trådlöst nätverk i Täppan. Det skulle då krävas tre basstationer på vardera plan för att uppnå bra täckning och prestanda.

  • 49.
    Backenhof, Albert
    Linköping University, Department of Science and Technology, Media and Information Technology.
    Automatic Generation of Collision Hulls for Polygonal Objects2011Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Physics in interactive environments, such as computer games, and simulations require well madeand accurate bounding volumes in order to act both realistically and fast. Today it is common to useeither inaccurate boxes or spheres as bounding volumes or to model the volume by hand. Thesemethods are either too inaccurate or require too much time to ever be able to be used in real-time,accurate virtual environments.This thesis presents a method to automatically generate collision hulls for both manifolds and nonmanifolds.This allows meshes to be used in a physical environment in just a few seconds and stillbeing able to behave realistically. The method performs Approximate Convex Decomposition byiteratively dividing the mesh into smaller, more convex parts. Every part is wrapped in a convexhull. Together the hulls make an accurate, but low cost, convex representation of the original mesh.The convex hulls are stored in a bounding volume hierarchy tree structure that enables fast testingfor collision with the mesh.

  • 50.
    Backman, Mattias
    Linköping University, Department of Electrical Engineering.
    Utvärdering av produkter för säker autentisering i Windowsmiljö2004Independent thesis Basic level (professional degree)Student thesis
    Abstract [en]

    In this report hardware based alternatives to password authentication in a Windows domain are evaluated for the needs of a certain company. In order to investigate the demands on such alternatives interviews with people concerned have been carried out. The demands which resulted from the interviews have been used to select types of hardware tokens for evaluation. Two products which offer authentication with smart cards and USB tokens have been selected and closer evaluated. These are RSA Passage which offers both hardware options and Rainbow iKey which uses USB tokens. Both products are evaluated based on the demands and additional evaluation criteria. The information from the evaluations is used to compare the products.

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