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  • 1.
    Grönwall, Christina
    et al.
    Linköping University, Department of Electrical Engineering, Automatic Control. Linköping University, The Institute of Technology.
    Gustafsson, Fredrik
    Linköping University, Department of Electrical Engineering, Automatic Control. Linköping University, The Institute of Technology.
    3D Content-Based Model Matching using Geometric Features2006Report (Other academic)
    Abstract [en]

    We present an approach that utilizes efficient geometric feature extraction and a matching method that takes articulation into account. It is primarily applicable for man-made objects. First the object is analyzed to extract geometric features, dimensions and rotation are estimated and typical parts, so-called functional parts, are identified. Examples of functional parts are a box's lid, a building's chimney, or a battle tank's barrel. We assume a model library with full annotation. The geometric features are matched with the model descriptors, to gain fast and early rejection of non-relevant models. After this pruning the objectis matched with relevant, usually few, library models. We propose a sequential matching, where the number of functional parts increases in each iteration. The division into parts increases the possibility for correct matching result when several similar models are available. The approach is exemplifi…ed with an vehicle recognition application, where some vehicles have functional parts.

  • 2.
    Al Faisal, Muhammad Saud
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    6-9 GHz UWB Antenna-Low-Noise Amplifier Co-design2012Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    6 - 9 GHz antenna-low-noise amplifier co-design is a demanding task. Higher frequency band has new techniques for circuit design and matching. The usual lumped component matching technique is not an appropriate solution for High Frequency (HF) broad band. The new broad band demands transmission line matching. The low-power and high-data rate Ultra Wide Band (UWB) uses large portion of the communication radio-spectrum and wireless communication. The principal axis of this thesis is co-design in the frequency band of 6 - 9 GHz. The thesis has been divided in two parts, where first part includes implementation and evaluation of individual RF-circuits of circular monopole antenna, a band pass (BP) filter and a low-noise amplifier (LNA), while second part unite all three RF circuits and presents the co-design.

    Microstrip monopole antennas get more and more popular due to rapid change in the wireless communication. Higher datarate and even higher bandwidth demands a simple and compact ultra-wideband (UWB) antenna. Two monopole antennas circular and rectangular monopole antennas were designed. Simulated and experimental results of modified design indicate that antenna was achieved a VSWR of 1.2, with input reflection less then - 10 dB in 4 - 12 GHz band. These characteristic make the designed antenna suitable for various UWB application.

     The broad band matching and the flat gain are the two important factors for the UWB circuits. The co-design of antenna-low-noise amplifier utilizes a inter stage matching technique with a simple band pass filter, a third-order passive Chebychev filter is proposed as an input matching network. The filter achieves forward transmission less the - 0.8 dB and a return loss - 20 dB in 6 - 9 GHz band.

    Low-noise amplifier is the key RF circuit; minimal Noise Figure (NF) and the lower power consumption are desired parameters. The implemented low-noise amplifier (LNA) is the combination of bias network and ultra-wide band radio frequency (RF) choke. AVAGO Technologies pseudmorphic-high-electron-mobility transistor (PHEMT) with (SC-70) plastic package with nominal 0.2 µm gate length is used in amplifier. Passive distributed components of microstrip transmission line were used for matching, simulated results demonstrate maximum power gain of 12.74 dB and minimum noise figure (NFmin) of 1 dB is obtained.

    Finally all three individual RF circuits antenna, filter and low-noise amplifier are integrated into co-design and analyzed for 6 - 9 GHz band. Later on two more new designs are added. This co-design has large potential in Direct-broadcast-satellite (DBS) TV system, X-band radar detector, automotive radar, remote sensors, and Multichannel-multipoint-distribution-systems (MMDS). 

  • 3.
    Lindblad, Ulrik
    et al.
    Linköping University, Department of Electrical Engineering.
    Thalin, Patrik
    Linköping University, Department of Electrical Engineering.
    A Behavioral Model of a DSP Processor with Scalable Structure2002Independent thesis Basic level (professional degree)Student thesis
    Abstract [en]

    In mobile digital devices, low power consumption is an important matter to reduce the need for a heavy and big battery. One way of reducing the power consumption is to construct the hardware so that the performance is optimal for the application. The demand of performance is dependent of the tasks that the device will be performing. This is where scalable structure of the hardware is an idea to solve the problem.

    This master thesis serve as a starting point for developing a digital signal processor with scalable structure. The digital signal processor is a common and important part of digital processing. Scalable struture is in this case adding and removing parts of the memory and/or the instruction set, and to make the data wordlength variable. The development is simplified by modeling it on an existing processor. The result of this master thesis is an instruction simulator written in C language. The simulator will be a model for development of the hardware.

  • 4.
    Saifullah, Mohammad
    Linköping University, Department of Computer and Information Science. Linköping University, The Institute of Technology.
    A Biologically Inspired Model for Occluded Patterns2011In: Neural Information Processing: proceedings of the 18th International Conference on Neural Information Processing, ICONIP 2011,  Shanghai, China, November 2011., 2011, 88-96 p.Conference paper (Refereed)
    Abstract [en]

    In this paper a biologically-inspired model for partly occluded patterns is proposed. The model is based on the hypothesis that in human visual system occluding patterns play a key role in recognition as well as in reconstructing internal representation for a pattern’s occluding parts. The proposed model is realized with a bidirectional hierarchical neural network. In this network top-down cues, generated by direct connections from the lower to higher levels of hierarchy, interact with the bottom-up information, generated from the un-occluded parts, to recognize occluded patterns. Moreover, positional cues of the occluded as well as occluding patterns, that are computed separately but in the same network, modulate the top-down and bottom-up processing to reconstruct the occluded patterns. Simulation results support the presented hypothesis as well as effectiveness of the model in providing a solution to recognition of occluded patterns. The behavior of the model is in accordance to the known human behavior on the occluded patterns.

  • 5.
    Svensson, Marlene
    Linköping University, Department of Management and Engineering.
    A CFD Investigation of a Generic Bump and its Application to a Diverterless Supersonic Inlet2008Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

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

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

  • 6.
    Sanchez Centellas, Daniel
    et al.
    Linköping University, Department of Clinical and Experimental Medicine, Division of Microbiology and Molecular Medicine. Linköping University, Faculty of Medicine and Health Sciences.
    Gudlur, Sushanth
    Linköping University, Department of Clinical and Experimental Medicine, Division of Microbiology and Molecular Medicine. Linköping University, Faculty of Medicine and Health Sciences. Nanyang Technology University, Singapore.
    Vicente Carrillo, Alejandro
    Linköping University, Department of Clinical and Experimental Medicine, Division of Clinical Sciences. Linköping University, Faculty of Medicine and Health Sciences.
    Ramström, Sofia
    Linköping University, Department of Clinical and Experimental Medicine, Division of Microbiology and Molecular Medicine. Linköping University, Faculty of Medicine and Health Sciences.
    Lindahl, Tomas
    Linköping University, Department of Clinical and Experimental Medicine, Division of Microbiology and Molecular Medicine. Linköping University, Faculty of Medicine and Health Sciences. Region Östergötland, Center for Diagnostics, Department of Clinical Chemistry.
    A cluster of aspartic residues in the extracellular loop II of PAR 4 is important for thrombin interaction and activation of platelets2017In: Thrombosis Research, ISSN 0049-3848, E-ISSN 1879-2472, Vol. 154, 98-106 p.Article in journal (Refereed)
    Abstract [en]

    Thrombin activates platelets via proteolytic cleavage of protease-activated receptors (PARs) 1 and 4. The two PARs have distinct but complementary roles. The mechanisms responsible for PAR1 activation by thrombin have been extensively studied. However, much less is known regarding thrombin activation of PAR4, especially the potential involvement of regions of PAR4 other than the N-terminal, which is bound to the catalytic site of thrombin. We have studied PAR4 in S. cerevisiae strainMMY12, an expression system in which the GPCR receptors are connected to a Lac Z reporter gene resulting in increased beta-galactosidase activity. This approach was used to assess PAR4 mutants to evaluate the contribution of different aspartic residues in facilitating PAR4 activation. Furthermore, peptides mimicking parts of the PAR4 N-terminal and the second extracellular loop (ECLII) were tested for their ability to inhibit platelet activation by thrombin. Binding of these peptides to gamma-thrombin was studied by monitoring the decrease in tryptophan fluorescence intensity of thrombin. We conclude that not only the N-terminal but also the electronegative aspartic residues D224, D230 and D235 (located in ECLII) are be important for PAR4 binding to thrombin. We further suggest that they play a role for the tethered ligand binding to the receptor, as mutations also affected activation in response to a PAR4-activating peptide mimicking the new N-terminal formed after cleavage. This agrees with previous results on PAR1 and thrombin binding. We suggest that the ECLII of PAR4 could be a potential target for antithrombotic drug development. (C) 2017 Elsevier Ltd. All rights reserved.

    The full text will be freely available from 2018-04-13 12:45
  • 7.
    Granlund, Gösta
    Linköping University, The Institute of Technology. Linköping University, Department of Electrical Engineering, Computer Vision.
    A Cognitive Vision Architecture Integrating Neural Networks with Symbolic Processing2006In: Künstliche Intelligenz, ISSN 0933-1875, no 2, 18-24 p.Article in journal (Other academic)
    Abstract [en]

    A fundamental property of cognitive vision systems is that they shall be extendable, which requires that they can both acquire and store information autonomously. The paper discusses organization of systems to allow this, and proposes an architecture for cognitive vision systems. The architecture consists of two parts. The first part, step by step learns a mapping from percepts directly onto actions or states. In the learning phase, action precedes perception, as action space is much less complex. This requires a semantic information representation, allowing computation and storage with respect to similarity. The second part uses invariant or symbolic representations, which are derived mainly from system and action states. Through active exploration, a system builds up concept spaces or models. This allows the system to subsequently acquire information using passive observation or language. The structure has been used to learn object properties, and constitutes the basic concepts for a European project COSPAL, within the IST programme.

  • 8.
    Fritzson, Peter
    Linköping University, Department of Computer and Information Science. Linköping University, The Institute of Technology.
    A Common Intermediate Representation for C, Pascal, Modula-2 and Fortran-771986Conference paper (Refereed)
    Abstract [en]

    This paper reports on a unified abstract syntax tree representation, called CIR, which is a program representation for a multi-language environment. The languages in question are C, Pascal, Modula-2 and Fortran-77. Nodes in this intermediate representation usually correspond to syntactic constructs in these languages. It is also possible to reconstruct source text from the CIR representation.It proved possible to achieve a fairly high degree of uniformity in the intermediate representation for the expression and statement parts of these languages. However, the declaration structure proved to be much more irregular, especially for C and Fortran-77. Also, some statistics on different node classes is presented for the languages involved, and a comparison to Diana is done.

  • 9.
    Gannholm, Lovisa
    Linköping University, Department of Computer and Information Science. Linköping University, The Institute of Technology.
    A Comparative Evaluation Between Two Design Solutions for an Information Dashboard2013Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    This study is a software usability design case about information presentation in a software dash­board. The dashboard is supposed to present system information about an enterprise resource planning system. The study aims to evaluate if the intended users of the dash­board prefer a list-based or an object-based presentation of the information and why. It also investigates if the possi­bility to get familiar with the prototype affects the evaluation’s result.

    The study was performed using parallel prototypes and evaluation with users. The use of parallel prototypes is a rather unexplored area. Likewise, little research has been done in the area of how user experience changes over time.

    Two prototypes were created, presenting the same information in two different design solutions, one list-based, and one object-based. The prototypes were evaluated with ten presumptive users, with respect to usability. The evaluation consisted of two parts, one quantitative and one qualita­tive. Half of the respondents got a chance to get familiar with the list-based prototype, and half the object-based prototype, after which they evaluated both sequentially.

    The result of the evaluation showed that seven out of ten respondents preferred the list-based prototype. The two primary reasons were that they are more used to the list-based concept from their work, and that the list-based prototype presented all information about an application at once. In the object-based prototype the user had to make a request for each type of information, which opened up in a new pop-up window.

    The primary reason that three of the ten respondents preferred the object-based prototype was that it had a more modern look, and gave a cleaner impression since it only presented the information the respondent was interested in at each point in time.

    The result also implied that the possibility to get familiar with the prototype by testing it for a couple of days affected the result. Eight out of ten respondents preferred the prototype they got familiar to, and the only ones that liked or preferred the object-based prototype were those who had gotten familiar with it.  

    The results of the study support the results of the existing research done by Dow et al. (2010) on the use of parallel prototypes, i.e. creating several prototypes in parallel, and conform with the results of the research of Karapanos et al. (2009) on how user experience changes over time.

    Some other interesting information that emerged from the study was that all but one of the respondents thought that the prototype they got familiar with had an acceptable level of usability.

    The study also validated that all respondents are positive to use a dashboard in their work, and that the presented information was enough for a first version of the dashboard. It also validated that the different groups of users would use the dashboard differently, and therefore are in need of slightly different information.

  • 10.
    Hildebrand, Cisilia
    et al.
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, The Institute of Technology.
    Hörtin, Stina
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, The Institute of Technology.
    A comparative study between Emme and Visum with respect to public transport assignment2014Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Macroscopic traffic simulations are widely used in the world in order to provide assistance in the traffic infrastructure development as well as for the strategic traffic planning. When studying a large traffic network macroscopic traffic simulation can be used to model current and future traffic situations. The two most common software used for traffic simulation in Sweden today are Emme and Visum, developed by INRO respective PTV.

    The aim of the thesis is to perform a comparison between the software Emme and Visum with respect to the assignment of public transport, in other words how passengers choose their routes on the existing public transport lines. However, in order to make a complete software comparison the run-time, analysis capabilities, multi-modality, capacity to model various behavioural phenomena like crowding, fares etc. this will not be done in this comparison. It is of interest to study the differences between the two software algorithms and why they might occur because the Swedish Transport Administration uses Emme and the Traffic Administration in Stockholm uses Visum when planning public transport. The comparison will include the resulting volumes on transit lines, travel times, flow through specific nodes, number of boarding, auxiliary volumes and number of transits. The goal of this work is to answer the following objective: What are the differences with modelling a public transport network in Emme and in Visum, based on that the passengers only have information about the travel times and the line frequency, and why does the differences occur?

    In order to evaluate how the algorithms work in a larger network, Nacka municipality (in Stockholm) and the new metro route between Nacka Forum and Kungsträdgården have been used. The motivation for choosing this area and case is due to that it is interesting to see what differences could occur between the programs when there is a major change in the traffic network.

    The network of Nacka, and parts of Stockholm City, has been developed from an existing road network of Sweden and then restricted by "cutting out" the area of interest and then removing all public transportation lines outside the selected area. The OD-matrix was also limited and in order not to loose the correct flow of travellers portal zones was used to collect and retain volumes.

    To find out why the differences occur the headway-based algorithms in each software were studied carefully. An example of a small and simple network (consisting of only a start and end node) has been used to demonstrate and show how the algorithms work and why volumes split differently on the existing transit lines in Emme and Visum. The limited network of Nacka shows how the different software may produce different results in a larger public transport network.

    The results show that there are differences between the program algorithms but the significance varies depending on which output is being studied and the size of the network. The Visum algorithm results in more total boardings, i.e. more passengers have an optimal strategy including a transit. The algorithms are very similar in both software programs, since they include more or less parts of the optimal strategy. The parameters used are taken more or less into consideration in Emme and Visum. For example Visum will first of all focus on the shortest total travel time and then consider the other lines with respect to the maximum waiting time. Emme however, first focuses on the shortest travel time and then considers the total travel time for other lines with half the waiting time instead of the maximum wait time. This results in that less transit lines will be attractive in Emme compared to Visum. The thesis concludes that varying the parameters for public transport in each software algorithm one can obtain similar results, which implies that it is most important to choose the best parameter values and not to choose the "best" software when simulating a traffic network.

  • 11.
    Nilsson, Jenny
    Linköping University, Department of Computer and Information Science.
    A Comparison Between Opaque and Transparent Displays for Vision Enhancement Systems2003Independent thesis Advanced level (degree of Magister)Student thesis
    Abstract [en]

    At night or in bad weather, the task of driving is very complex since the amount of visual information available is severely reduced. Vision Enhancement Systems may compensate for parts of the missing information by supplying the driver with a picture of the world where warm objects are made visible. This thesis investigates the impact of Vision Enhancement System display types on cognitive capture and driving performance. 16 subjects were recruited for a simulator study. It was hypothesised that when the contrast of a transparent display is high enough for the driver to separate the picture from the background and make out enough details to interpret it, the risk of cognitive capture is higher than when using an opaque display with the same objects visible. The subjects’ driving performance and opinions about the driving experience were also investigated. No significant differences in driving performance or level of cognitive capture was found. However, questionnaire answers indicate that this question needs to be investigated further to find out whether one display type is preferable because of better and safer driving performance or if individual differences between drivers require the possibility to choose the display type of their personal preference.

  • 12.
    Engström, Jens
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    A comparison between the Eurocodes and BKR2006Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Between the year 2008 and 2011 a new code of pracitce for construction of buildings will replace our present code. This new code is called Eurocodes and consists of ten different parts.

    In this degree thesis the different calculationmodels in Eurocodes and in our Swedish code of practice, BKR, is presented and compared. The fields included are Loads and combination of loads, Classes of safety and Concrete-/Steelstructures. The main purpose with this degree thesis is to investigate if there are any differences in the safetylevel between the codes. In order to do this, results from loadcalculations and calculations of materialcharaceristics have been compared.

    It can be stated that the safetyaspects is treated differently in the two codes. BKR gives the opportunity to adapt the safetylevel according to the buildings usage, which gives a more exact and costefficient system. At the same time calculations according to Eurocodes gives rougher dimensions and because of this a higher safetylevel.

  • 13.
    Zetterqvist, Maria
    et al.
    Linköping University, Department of Clinical and Experimental Medicine, Child and Adolescent Psychiatry. Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Local Health Care Services in Central Östergötland, Department of Child and Adolescent Psychiatry in Linköping.
    Lundh, Lars-Gunnar
    Lund University, Sweden .
    Svedin, Carl Göran
    Linköping University, Department of Clinical and Experimental Medicine, Division of Clinical Sciences. Linköping University, Faculty of Health Sciences.
    A Comparison of Adolescents Engaging in Self-Injurious Behaviors With and Without Suicidal Intent: Self-Reported Experiences of Adverse Life Events and Trauma Symptoms2013In: Journal of Youth and Adolescence, ISSN 0047-2891, E-ISSN 1573-6601, Vol. 42, no 8, 1257-1272 p.Article in journal (Refereed)
    Abstract [en]

    Research comparing adolescents engaging in suicidal and non-suicidal self-injury (NSSI), both separately and in combination, is still at an early stage. The purpose of the present study was to examine overlapping and distinguishable features in groups with different types of self-injurious behaviors, using a large community sample of 2,964 (50.6 % female) Swedish adolescents aged 15-17 years. Adolescents were grouped into six categories based on self-reported lifetime prevalence of self-injurious behaviors. Of the total sample, 1,651 (55.7 %) adolescents reported no self-injurious behavior, 630 (21.2 %) reported NSSI 1-4 times, 177 (6.0 %) reported NSSI 5-10 times, 311 (10.5 %) reported NSSI a parts per thousand yen 11 times, 26 (0.9 %) reported lifetime prevalence of suicide attempt and 169 (5.7 %) adolescents reported both NSSI and suicide attempt. After controlling for gender, parental occupation and living conditions, there were significant differences between groups. Pairwise comparisons showed that adolescents with both NSSI and suicide attempt reported significantly more adverse life events and trauma symptoms than adolescents with only NSSI, regardless of NSSI frequency. The largest differences (effect sizes) were found for interpersonal negative events and for symptoms of depression and posttraumatic stress. Adolescents with frequent NSSI reported more adversities and trauma symptoms than those with less frequent NSSI. There were also significant differences between all the NSSI groups and adolescents without any self-injurious behavior. These findings draw attention to the importance of considering the cumulative exposure of different types of adversities and trauma symptoms when describing self-injurious behaviors, with and without suicidal intent.

  • 14.
    Stymne, Sara
    Linköping University, Department of Computer and Information Science, NLPLAB - Natural Language Processing Laboratory. Linköping University, The Institute of Technology.
    A Comparison of Merging Strategies for Translation of German Compounds2009In: Proceedings of the Student Research Workshop at the 12th Conference of the European Chapter of the ACL (EACL 2009), Association for Computational Linguistics , 2009, 61-69 p.Conference paper (Refereed)
    Abstract [en]

    In this article, compound processing for translation into German in a factored statistical MT system is investigated. Compound sare handled by splitting them prior to training, and merging the parts after translation. I have explored eight merging strategies using different combinations of external knowledge sources, such as word lists, and internal sources that are carried through the translation process, such as symbols or parts-of-speech. I show that for merging to be successful, some internal knowledge source is needed. I also show that an extra sequence model for part-ofspeech is useful in order to improve the order of compound parts in the output. The best merging results are achieved by a matching scheme for part-of-speech tags.

  • 15. Hilding, D.
    et al.
    Torstenfelt, Bo
    Linköping University, The Institute of Technology. Linköping University, Department of Management and Engineering, Solid Mechanics .
    Klarbring, Anders
    Linköping University, The Institute of Technology. Linköping University, Department of Management and Engineering, Mechanics .
    A computational methodology for shape optimization of structures in frictionless contact2001In: Computer Methods in Applied Mechanics and Engineering, ISSN 0045-7825, Vol. 190, no 31, 4043-4060 p.Article in journal (Refereed)
    Abstract [en]

    This paper presents a computational methodology for shape optimization of structures in frictionless contact, which provides a basis for developing user-friendly and efficient shape optimization software. For evaluation it has been implemented as a subsystem of a general finite element software. The overall design and main principles of operation of this software are outlined. The parts connected to shape optimization are described in more detail. The key building blocks are: analytic sensitivity analysis, an adaptive finite element method, an accurate contact solver, and a sequential convex programing optimization algorithm. Results for three model application examples are presented, in which the contact pressure and the effective stress are optimized. cr 2001 Elsevier Science B.V. All rights reserved.

  • 16. Sparring Björkstén, Karin
    et al.
    Ekberg, Stefan
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Medicine and Care, Radiation Physics. Östergötlands Läns Landsting, Centre of Surgery and Oncology, Department of Radiation Physics.
    Säfström, Pia
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Medicine and Care, Medical Radiology. Östergötlands Läns Landsting, Centre for Medical Imaging, Department of Radiology UHL.
    Dige, N
    Granerus, Göran
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Medicine and Care, Clinical Physiology. Östergötlands Läns Landsting, Heart Centre, Department of Clinical Physiology.
    A computerized human reference brain for rCBF/SPET technetium-99m exametazime (HMPAO) investigation of elderly2004In: Clinical Physiology and Functional Imaging, ISSN 1475-0961, Vol. 24, no 4, 196-204 p.Article in journal (Refereed)
    Abstract [en]

    Using the bull's eye approach, a reference brain from the single photon emission tomography (SPET) images of 10 subjects aged 62-81 years with excellent mental and physical health was constructed. SPET images were acquired twice, 1 week apart, using a single detector rotating gamma camera collecting 64 planar images over a 360° orbit. The centre of each transaxial slice was first defined with an automatic edge detecting algorithm applied to an anterior-posterior and a side profile of the brain. Each slice was divided into 40 sectors. Maximum counts/pixel in each sector was picked. The 40 maximum count values from one transaxial slice were allowed to form a horizontal row in a new parametric image on the x-axis and slice number from the vertex to the basal parts of the brain on the y-axis. This new image was scaled to a 64 × 16 pixel matrix by interpolation, which meant a normalization of all studies to the same size. The parametric image in each subject was scaled with regard to intensity by a factor calculated by a normalization procedure using the least squares analysis. Mean and SD for each pixel were calculated, thereby constructing a 'mean parametric image', and a 'SD parametric image'. These two images are meant to be used as the reference brain for evaluation of patient studies. This method can be used for objective measurements of diffuse brain changes and for pattern recognition in larger groups of patients. Statistical multifactorial analysis of parameters used for acquisition and data processing is possible. © 2004 Blackwell Publishing Ltd.

  • 17.
    Broberg, C.
    et al.
    Inst. of Occup. Therapy/Physiother., Sahlgrenska Acad. at Goteborg Univ., P.O. Box 455, SE 405 30 Göteborg, Sweden.
    Aars, M.
    School of Physiotherapy, Faculty of Health Sciences, Tromsø University College, Tromsø, Norway.
    Beckmann, Kristina
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Medicine and Health Sciences, Physiotherapy.
    Emaus, N.
    School of Physiotherapy, Faculty of Health Sciences, Tromsø University College, Tromsø, Norway.
    Lehto, P.
    Degree Programme in Physiotherapy, Pirkanmaa Polytechnic, Tampere, Finland.
    Lahteenmaki, M.-L.
    Lähteenmäki, M.-L..
    Licentiate, A.
    Degree Programme in Physiotherapy, Pirkanmaa Polytechnic, Tampere, Finland.
    Thys, W.
    Department of Physiotherapy, Arteveldehogeschool, Gent, Belgium.
    Vandenberghe, R.
    Department of Physiotherapy, Arteveldehogeschool, Gent, Belgium.
    A conceptual framework for curriculum design in physiotherapy education - An international perspective2003In: Advances in Physiotherapy, ISSN 1403-8196, Vol. 5, no 4, 161-168 p.Article in journal (Refereed)
    Abstract [en]

    Globalization is having a significant impact on healthcare and physiotherapy education, among other sectors, can benefit from this trend. The main aim of this work was to develop and describe a conceptual framework for physiotherapy curriculum design and, in doing so, to stimulate international debate on physiotherapy education. The framework was developed through an international collaboration and was tried out in the participating schools in order to refine it further. The current framework consists of three elements to be taken into account in physiotherapy curriculum design: (1) The content aspect or the knowledge base of physiotherapy, (2) the learning aspect or the student's learning process, and (3) the socio-cultural context aspect, which concerns the way in which physiotherapy is experienced and practised. The content aspect includes a description of core concepts of physiotherapy: body, movement and interaction, and acknowledges that physiotherapy should be science-based. The learning aspect and the socio-cultural context aspect form separate parts of the framework. Nonetheless, all aspects are intertwined and reflect theory-practice integration. This framework is offered for critical reflection and as the basis for a debate on the development and evaluation of physiotherapy programmes. Further work is needed in testing the relevance of this framework for curriculum design in different countries and setting.

  • 18.
    Felsberg, Michael
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Electrical Engineering, Computer Vision.
    Forssén, Per-Erik
    Linköping University, The Institute of Technology. Linköping University, Department of Electrical Engineering, Computer Vision.
    Moe, Anders
    Linköping University, The Institute of Technology. Linköping University, Department of Electrical Engineering, Computer Vision.
    Granlund, Gösta
    Linköping University, The Institute of Technology. Linköping University, Department of Electrical Engineering, Computer Vision.
    A COSPAL Subsystem: Solving a Shape-Sorter Puzzle2005In: AAAI Fall Symposium: From Reactive to Anticipatory Cognitive Embedded Systems, FS-05-05, AAAI Press , 2005, 65-69 p.Conference paper (Refereed)
    Abstract [en]

     To program a robot to solve a simple shape-sorter puzzle is trivial. To devise a Cognitive System Architecture, which allows the system to find out by itself how to go about a solution, is less than trivial. The development of such an architecture is one of the aims of the COSPAL project, leading to new techniques in vision based Artificial Cognitive Systems, which allow the development of robust systems for real dynamic environments. The systems developed under the project itself remain however in simplified scenarios, likewise the shape-sorter problem described in the present paper. The key property of the described system is its robustness. Since we apply association strategies of local features, the system behaves robustly under a wide range of distortions, as occlusion, colour and intensity changes. The segmentation step which is applied in many systems known from literature is replaced with local associations and view-based hypothesis validation. The hypotheses used in our system are based on the anticipated state of the visual percepts. This state replaces explicit modeling of shapes. The current state is chosen by a voting system and verified against the true visual percepts. The anticipated state is obtained from the association to the manipulator actions, where reinforcement learning replaces the explicit calculation of actions. These three differences to classical schemes allow the design of a much more generic and flexible system with a high level of robustness. On the technical side, the channel representation of information and associative learning in terms of the channel learning architecture are essential ingredients for the system. It is the properties of locality, smoothness, and non-negativity which make these techniques suitable for this kind of application. The paper gives brief descriptions of how different system parts have been implemented and show some examples from our tests.

  • 19.
    Lundin, Rolf A.
    et al.
    Jönköping International Business School, Jönköping, Sweden.
    Sundin, Elisabeth
    Linköping University, Department of Management and Engineering, Business Administration. Linköping University, Faculty of Arts and Sciences.
    A Dark Side ofInternationalization2013In: Final Program and Abstracts / [ed] Lars Engvall, Antti Alanamo and Kerstin Sahlin, 2013Conference paper (Other academic)
    Abstract [en]

    The importance of internationalization for Sweden has for a long time been hot on the political agenda. The academic field is part of a strong support of internationalization ambitions. But there are degenerate species of internationalization to keep a sharp eye on. One we have in mind concerns how applicants for academic positions are evaluated.

    Part of this internationalization is that publications in international journals (mostly American or British) are expected to be the prime criteria in evaluation for academic positions. Evaluations also seem to be transformed into a mathematical exercise where content in fact does not count, but only the numbers of publications and the rankings of the journals. A similar trend is the demand for international evaluators of all parts of our national system which is research programs, applications for financial resources for research programs, projects and positions. International is also when it comes to these matters almost equated with experts from the US orwestern Europe even though the academic landscape is transformed worldwide.

    We question this trend: Is quality promoted in this way? Scandinavian/Nordic systems have qualities that are worth protecting. We will elaborate on our standpoints and give some examples from our own experiences as evaluators and experts.

    We will also argue that the methods used by many international colleagues could be seen as part of a devaluation of the professional academic system. Unfortunately, we expect the methods used to be the standard in the years to come.

  • 20.
    Henriksson, Ola
    Linköping University, Department of Science and Technology.
    A Depth of Field Algorithm for Realtime 3D Graphics in OpenGL2002Independent thesis Basic level (professional degree)Student thesis
    Abstract [en]

    The company where this thesis was formulated constructs VR applications for the medical environment. The hardware used is ordinary dektops with consumer level graphics cards and haptic devices. In medicin some operations require microscopes or cameras. In order to simulate these in a virtual reality environment for educational purposes, the effect of depth of field or focus have to be considered.

    A working algorithm that generates this optical occurence in realtime, stereo rendered computer graphics is presented in this thesis. The algorithm is implemented in OpenGL and C++ to later be combined with a VR application simulating eye-surgery which is built with OpenGL Optimizer.

    Several different approaches are described in this report. The call for realtime stereo rendering (~60 fps) means taking advantage of the graphics hardware to a great extent. In OpenGL this means using the extensions to a specific graphic chip for better performance, in this case the algorithm is implemented for a GeForce3 card.

    To increase the speed of the algorithm much of the workload is moved from the CPU to the GPU (Graphics Processing Unit). By re-defining parts of the ordinary OpenGL pipeline via vertex programs, a distance-from-focus map can be stored in the alpha channel of the final image with little time loss.

    This can effectively be used to blend a previously blurred version of the scene with a normal render. Different techniques to quickly blur a renderedimage is discussed, to keep the speed up solutions that require moving data from the graphics card is not an option.

  • 21.
    Gustafsson, Mikael
    et al.
    Linköping University, Department of Molecular and Clinical Medicine, Medical Microbiology. Linköping University, Faculty of Health Sciences.
    Magnusson, Karl-Eric
    Linköping University, Department of Molecular and Clinical Medicine, Medical Microbiology. Linköping University, Faculty of Health Sciences.
    A distributed image-processing system for measurements of intracellular calcium in living cells1991In: Computer Methods and Programs in Biomedicine, ISSN 0169-2607, E-ISSN 1872-7565, Vol. 36, no 4, 199-221 p.Article in journal (Refereed)
    Abstract [en]

    During the last decade, image-processing techniques have been introduced as a valuable tool in biologically oriented research. In combination with novel fluorescent probes, these techniques permit assessment of subcellular distributions of several intracellularly important cations, such as free calcium ions and protons. Typically, systems used for image processing are located centrally around the experimental setup. This configuration has drawbacks, mainly because the laborious extraction and processing of data that generally follow an experimental session limits the access to the system for other investigators. We describe here the principles of a distributed image processing system, based on IBM-compatible personal computers (PCs), that without extra hardware can cope with all the necessary image processing involved in imaging of intracellular cations. The potential of the PC as an image processor, however, reaches beyond this specific application and many image processing tasks can be carried out successfully on a standard PC. Thus, the centrally located dedicated image processor is used only for image acquisition in the experimental situation. This in turn optimizes the utilization of expensive resources and increases efficiency. The mouse-operated software is described in detail, so that interested investigators can extract useful parts for integration into their own applications and experimental environment.

  • 22.
    Tell, Eric
    Linköping University, Department of Electrical Engineering.
    A Domain Specific DSP Processor2001Independent thesis Basic level (professional degree)Student thesis
    Abstract [en]

    This thesis describes the design of a domain specific DSP processor. The thesis is divided into two parts. The first part gives some theoretical background, describes the different steps of the design process (both for DSP processors in general and for this project) and motivates the design decisions made for this processor.

    The second part is a nearly complete design specification.

    The intended use of the processor is as a platform for hardware acceleration units. Support for this has however not yet been implemented.

  • 23.
    Korishe, Abdulah
    Linköping University, Department of Electrical Engineering, Electronics System.
    A Driver Circuit for Body-Coupled Communication2013Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The main concept of Body-Coupled Communication (BCC) is to transmit the electrical information through the human body as a communication medium by means of capacitive coupling. Nowadays the current research of wireless body area network are expanding more with the new ideas and topologies for better result in respect to the low power and area, security, reliability and sensitivity since it is first introduced by the Zimmerman in 1995. In contrast with the other existing wireless communication technology such as WiFi, Bluetooth and Zigbee, the BCC is going to increase the number of applications as well as solves the problem with the cell based communication system depending upon the frequency allocation. In addition, this promising technology has been standardized by a task group named IEEE 802.15.6 addressing a reliable and feasible system for low power in-body and on-body nodes that serves a variety of medical and non medical applications.

    The entire BAN project is divided into three major parts consisting of application layer, digital baseband and analog front end (AFE) transceiver. In the thesis work a strong driver circuit for BCC is implemented as an analog front end transmitter (Tx). The primary purpose of the study is to transmit a strong signal as the signal is attenuated by the body around 60 dB. The Driver circuit is cascaded of two single-stage inverter and an identical inverter with drain resistor. The entire driver circuit is designed with ST65 nm CMOS technology with 1.2 V supply operated at 10 MHz frequency, has a driving capability of 6 mA which is the basic requirement. The performance of the transmitter is compared with the other architecture by integrating different analysis such as corner analysis, noise analysis and eye diagram. The cycle to cycle jitter is 0.87% which is well below to the maximum point and the power supply rejection ratio (PSRR) is 65 dB indicates the good emission of supply noise. In addition, the transmitter does not require a filter to emit the noise because the body acts like a low pass filter.

    In conclusion the findings of the thesis work is quite healthy compared to the previous work. Finally, there is some point to improve for the driver circuit in respect to the power consumption, propagation delay and leakage power in the future.   

  • 24.
    Nikkar, Samira
    et al.
    Linköping University, Department of Mathematics, Computational Mathematics. Linköping University, Faculty of Science & Engineering.
    Nordström, Jan
    Linköping University, Department of Mathematics, Computational Mathematics. Linköping University, Faculty of Science & Engineering.
    A dual consistent summation-by-parts formulation for the linearized incompressible Navier-Stokes equations posed on deforming domains2016Report (Other academic)
    Abstract [en]

    In this article, well-posedness and dual consistency of the linearized incompressible Navier-Stokes equations posed on time-dependent spatial domains are studied. To simplify the derivation of the dual problem, the second order formulation is transformed to rst order form. Boundary conditions that simultaneously lead to well-posedness of the primal and dual problems are derived.

    We construct fully discrete nite di erence schemes on summation-byparts form, in combination with the simultaneous approximation technique. We prove energy stability and discrete dual consistency. Moreover, we show how to construct the penalty operators such that the scheme automatically adjusts to the variations of the spatial domain, and as a result, stability and discrete dual consistency follow simultaneously.

    The method is illustrated by considering a deforming time-dependent spatial domain in two dimensions. The numerical calculations are performed using high order operators in space and time. The results corroborate the stability of the scheme and the accuracy of the solution. We also show that linear functionals are superconverging. Additionally, we investigate the convergence of non-linear functionals and the divergence of the solution.

  • 25.
    Söderberg, Johan
    Linköping University, Department of Management and Engineering, Mechanics. Linköping University, The Institute of Technology.
    A finite element method for calculating load distributions in bolted joint assemblies2012Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Bolted joints are often the most critical parts with respect to fatigue life of structures. Therefore, it is important to analyze these components and the forces they are subjected to.

    A one-dimensional nite element model of a bolted joint is created and implemented as a program module in the Saab software `DIM', together with a complete graphical user interface allowing the user to generate the structure freely, and to apply both mechanical and thermal loads.

    Available methods for calculating fastener exibility are reviewed. The ones derived by Grumman, Huth and Barrois are implemented in the module, and can thus be used when dening a geometry representing a bolted joint assembly. Investigations have shown that it cannot be said that either method is generally better than the other. Calculated properties of interest include the fastener forces, plate bearing and bypass loads, and - for simpler geometries without thermal loads - the load distribution between rows of fasteners.

    The program is fully functional and yields numerically accurate results for the most commonly used joints where fasteners connect two or three plates each. It has limited functionality on geometries with fasteners connecting four or more plates and for a certain loading combination also for three plates, due to the tilting of the fasteners not being accounted for in the model for these cases. Also, there is no explicit method available for nding an accurate value for the fastener exibility for these, less common, joint structures.

  • 26.
    Rietz, Andreas
    Linköping University, Department of Mathematics, Applied Mathematics. Linköping University, The Institute of Technology.
    A first laboratory exercise in topology optimization using matlab2006Report (Other academic)
    Abstract [en]

    The purpose of this laboratory exercise is to give you experience with the use of topology optimization as a first design tool in doing a construction. A 99 line topology optimization code written in Matlab will be used. The code is available at

    http://www.topopt.dtu.dk

    The details are explained in the paper “A 99 line topology optimization code writter in Matlab” which is published in the journal “Structual and Multidisciplinary Optimization” by Ole Sigmund, dept. of solid mechanics at Technical University of Denmark. The matlab code is also included as an appendix.

    This matlab code should give understanding of the basics of a topology optimization program, and the user can easily modify the code

    The laboratory exercise is divided into two parts. The first part is about the design of bicycles and is intended to make you familiar with the methodology and the matlab code. The second part consists of a bunch of projects that can be treated in the same way as the bicycle. It is advisable to choose one of the projects in the second part.

  • 27.
    Carlsson, Marianne
    et al.
    Uppsala universitet Uppsala.
    Arman, Maria
    Karolinska institutet Stockholm.
    Backman, Maria
    Röda Korsets Högskola Stockholm.
    Flatters, Ursula
    Vidarkliniken Järna.
    Hatschek, Thomas
    Karolinska inst Stockholm.
    Hamrin, Elisabeth
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Medicine and Health Sciences, Clinical Pharmacology .
    A five-year follow-up of quality of life in women with breast cancer in anthroposophic and conventional care2006In: Evidence-based Complementary and Alternative Medicine, ISSN 1741-427X, Vol. 3, no 4, 523-531 p.Article in journal (Refereed)
    Abstract [en]

    Complementary and alternative medicine is used by many cancer patients in most parts of the world, and its use is increasing. The aim of the present study was to examine, over 5 years, the perceived quality of life/life satisfaction in two samples of women with breast cancer who were treated with anthroposophic care or conventional medical treatment only. Data from admission, after 1 year and after 5 years are used for the comparisons. On admission to the study the women in anthroposophic care perceived their quality of life to be lower than that of the women in the conventional treatment group, especially for emotional, cognitive and social functioning and overall quality of life. Sixty women who actively chose treatment with anthroposophic medicine and 60 individually matched women treated with conventional medicine participated. Quality of life was measured by the EORTC QLQ-C30 and the Life Satisfaction Questionnaire. Twenty-six women within anthroposophic care and 31 women within conventional medicine survived the 5 years. Effect size (ES) estimation favored the anthroposophic group in seven of the subscales mostly measuring emotional functioning. The ES for four of the subscales favored the conventional treatment group, mostly concerning physical functioning. After 5 years there were improvements in overall quality of life and in emotional and social functioning compared to admission for the women in anthroposophic care. The improvements took place between admission and 1 year, but not further on. Only minor improvements were found in the matching group. © 2006 The Author (s).

  • 28.
    Nordström, Jan
    et al.
    Linköping University, Department of Mathematics, Computational Mathematics. Linköping University, The Institute of Technology.
    Abbas, Qaisar
    Department of Information Technology, Division of Scientific Computing, Uppsala University, SE-751 05 Uppsala, Sweden.
    Erickson, Brittany A.
    Department of Geological Sciences, San Diego State University, San Diego, CA 92182-1020, USA.
    Frenander, Hannes
    Linköping University, Department of Mathematics, Computational Mathematics. Linköping University, The Institute of Technology.
    A Flexible Boundary Procedure for Hyperbolic Problems: Multiple Penalty Terms Applied in a Domain2014In: Communications in Computational Physics, ISSN 1815-2406, E-ISSN 1991-7120, Vol. 16, no 2, 541-570 p.Article in journal (Refereed)
    Abstract [en]

    A new weak boundary procedure for hyperbolic problems is presented. We consider high order finite difference operators of summation-by-parts form with weak boundary conditions and generalize that technique. The new boundary procedure is applied near boundaries in an extended domain where data is known. We show how to raise the order of accuracy of the scheme, how to modify the spectrum of the resulting operator and how to construct non-reflecting properties at the boundaries. The new boundary procedure is cheap, easy to implement and suitable for all numerical methods, not only finite difference methods, that employ weak boundary conditions. Numerical results that corroborate the analysis are presented.

  • 29.
    Nordström, Jan
    et al.
    Linköping University, Department of Mathematics, Computational Mathematics. Linköping University, The Institute of Technology.
    Abbas, Qaisar
    Department of Information Technology, Division of Scientific Computing, Uppsala University, SE-751 05 Uppsala, Sweden.
    A. Erickson, Brittany
    Department of Geological Sciences, San Diego State University, San Diego, CA 92182-1020, USA.
    Frenander, Hannes
    Linköping University, Department of Mathematics, Computational Mathematics. Linköping University, The Institute of Technology.
    A Flexible Far Field Boundary Procedure for Hyperbolic Problems: Multiple Penalty Terms Applied in a Domain2013Report (Other academic)
    Abstract [en]

    A new weak boundary procedure for hyperbolic problems is presented. We consider high order finite difference operators of summation-by-parts form with weak boundary conditions and generalize that technique. The new boundary procedure is applied at far field boundaries in an extended domain where data is known. We show how to raise the order of accuracy of the scheme, how to modify the spectrum of the resulting operator and how to construct non-reflecting properties at the boundaries. The new boundary procedure is cheap, easy to implement and suitable for all numerical methods, not only finite difference methods, that employ weak boundary conditions. Numerical results that corroborate the analysis are presented.

  • 30.
    Törnå, Jonas
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    A flow mapping of asphalt works2010Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    The purpos of this study i to examin how the flow apperars as two different machine working team at Skanska coating in Norrköping. its also to explore possible improvements and benefits there are to extract. And investigate how the actions can activity in a constand development and increasing production effiency.

    The report is divided into three parts. part one deals with a background desciption of skanska, and explantion of potential benefits. after follows the section where and discussion section. the eassy completes with an analysis and discussion section. the discussion and analysis are based with an result from the study section.

  • 31.
    Carlsson, Jonas
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Bioinformatics . Linköping University, The Institute of Technology.
    Vahdat Shariatpanahi, Aida
    Schultz, Sebastian
    Linköping University, Department of Clinical and Experimental Medicine, Cell Biology. Linköping University, Faculty of Health Sciences.
    Westermark, Gunilla
    Linköping University, Department of Clinical and Experimental Medicine, Cell Biology. Linköping University, Faculty of Health Sciences.
    Persson, Bengt
    Linköping University, Department of Physics, Chemistry and Biology, Bioinformatics . Linköping University, The Institute of Technology.
    A folding study on IAPP (Islet Amyloid Polypeptide) using molecular dynamics simulationsManuscript (preprint) (Other academic)
    Abstract [en]

    Amyloidosis is the largest group among the protein misfolding diseases, and includes well known diseases such as Alzheimer’s disease and type 2 diabetes. In the latter, islet amyloid is present in the pancreas in almost all individuals. Today, more than 25 different proteins have been isolated from amyloid deposits in human. Even though these proteins differ in size, charge and sequence they all have the capacity to assemble in to fibrillar structures with inseparable morphological appearance. Therefore, it can be assumed that the fibril process is based upon principles that are general for all proteins and knowledge derived from one protein can be used for other amyloid proteins. In this paper, we study the process of amyloid formation in parts of islet amyloid polypeptide (residues 18-29 and 11-37) by analyzing mutations using three different in silico methods. Finally, we use the methods to predict the amyloidogenic properties of the native IAPP and 16 variants thereof and compare the result with in vitro measurements. Using a consensus prediction of the three methods we managed to correctly classify all but two peptides. We have also given further evidence to the importance of S28P for inhibiting amyloid fibre formation, found evidence for antiparallel stacking, and identified important regions for beta sheet stability.

  • 32.
    Sylverberg, Tomas
    Linköping University, Department of Computer and Information Science.
    A Framework for Mobile Paper-based Computing2007Independent thesis Advanced level (degree of Magister), 20 points / 30 hpStudent thesis
    Abstract [en]

    Military work-practice is a difficult area of research where paper-based approaches are still extended. This thesis proposes a solution which permits the digitalization of information at the same time as workpractice remains unaltered for soldiers working with maps in the field. For this purpose, a mobile interactive paper-based platform has been developed which permits the users to maintain their current work-flow. The premise of the solution parts from a system consisting of a prepared paper-map, a cellular phone, a desktop computer, and a digital pen with bluetooth connection. The underlying idea is to permit soldiers to take advantage of the information a computerized system can offer, at the same time as the overhead it incurs is minimized. On one hand this implies that the solution must be light-weight, on the other it must retain current working procedures as far as possible. The desktop computer is used to develop new paper-driven applications through the application provided in the development framework, thus allowing the tailoring of applications to the changing needs of military operations. One major component in the application suite is a symbol recognizer which is capable of recognizing symbols parting from a template which can be created in one of the applications. This component permits the digitalization of information in the battlefield by drawing on the paper-map. The proposed solution has been found to be viable, but still there is a need for further development. Furthermore, there is a need to adapt the existing hardware to the requirements of the military to make it usable in a real-world situation.

  • 33.
    Padgham, Lin
    et al.
    Linköping University, Department of Computer and Information Science. Linköping University, The Institute of Technology.
    Lambrix, Patrick
    Linköping University, Department of Computer and Information Science, Database and information techniques. Linköping University, Faculty of Science & Engineering.
    A Framework for Part-of Hierarchies in Terminological Logics1994In: Principles of Knowledge Representation and Reasoning - Proceedings of the Fourth International Conference - KR 94, Morgan Kaufmann Publishers, 1994, 485-496 p.Conference paper (Refereed)
    Abstract [en]

    There is a growing recognition that part-whole hierarchies are a very general form of representation, widely used by humans in commonsense reasoning. This paper develops a terminological logic, and related inference mechanisms for representing and reasoning about composite concepts and individuals. A basic terminological logic language is extended with constructs for describing composite concepts in terms of their parts and the relationships between them. A part-of hierarchy is defined, based on the relationship of compositional inclusion. This part-of hierarchy is analogous to, but different from, the “is-a” hierarchy. Compositional inferencing is defined as a process which infers the existence of a whole, based on the existence of the required parts, where the parts are in the necessary relationship to each other. Three stable states are defined with respect to compositional inferencing - compositional extensions, credulous compositional extensions and skeptical compositional conclusions. This framework significantly enhances and is complementary to, knowledge representation and reasoning based on is-a hierarchies.

  • 34.
    Kocak, Umut
    et al.
    Linköping University, Department of Science and Technology, Visual Information Technology and Applications (VITA). Linköping University, The Institute of Technology.
    Palmerius, Karljohan
    Linköping University, Department of Science and Technology, Visual Information Technology and Applications (VITA). Linköping University, The Institute of Technology.
    Ynnerman, Anders
    Linköping University, Department of Science and Technology, Visual Information Technology and Applications (VITA). Linköping University, The Institute of Technology.
    A framework for Soft-tissue Deformation2009In: Proceedings of SIGRAD Conference 2009, 2009, 27-29 p.Conference paper (Other academic)
    Abstract [en]

    For the simulation of soft tissue deformation Finite ElementMethod (FEM) has been the technique which achieves most physicallyrealistic behaviour. However to provide stable force feedback,high refresh rates are needed which makes the use of FEMnon-trivial.To solve the challenge of the compromise between speed and realism,asynchronous regions which solves different parts of the modelwith different frequencies and different resolutions are used. Thelocal neighbourhood of the contact is solved with higher frequencyand resolution while the more remote regions are solved with lowerfrequency and resolutions. Different solution methods, implicit andexplicit, can be used to solve different regions and the size of theregions can be adapted depending on the strain to maximize theefficiency.

  • 35.
    Nikkar, Samira
    et al.
    Linköping University, Department of Mathematics, Computational Mathematics. Linköping University, Faculty of Science & Engineering.
    Nordström, Jan
    Linköping University, Department of Mathematics, Computational Mathematics. Linköping University, Faculty of Science & Engineering.
    A fully discrete, stable and conservative summation-by-parts formulation for deforming interfaces2016Report (Other academic)
    Abstract [en]

    We introduce an interface/coupling procedure for hyperbolic problems posedon time-dependent curved multi-domains. First, we transform the problem from Cartesian to boundary-conforming curvilinear coordinates and apply the energy method to derive well-posed and conservative interface conditions.

    Next, we discretize the problem in space and time by employing finite difference operators that satisfy a summation-by-parts rule. The interface condition is imposed weakly using a penalty formulation. We show how to formulate the penalty operators such that the coupling procedure is automatically adjusted to the movements and deformations of the interface, while both stability and conservation conditions are respected.

    The developed techniques are illustrated by performing numerical experiments on the linearized Euler equations and the Maxwell equations. The results corroborate the stability and accuracy of the fully discrete approximations.

  • 36.
    Nikkar, Samira
    et al.
    Linköping University, Department of Mathematics, Computational Mathematics. Linköping University, Faculty of Science & Engineering.
    Nordström, Jan
    Linköping University, Department of Mathematics, Computational Mathematics. Linköping University, Faculty of Science & Engineering.
    A fully discrete, stable and conservative summation-by-parts formulation for deforming interfaces2017In: Journal of Computational Physics, ISSN 0021-9991, E-ISSN 1090-2716, Vol. 339, 25 p.500-524 p.Article in journal (Refereed)
    Abstract [en]

    We introduce an interface/coupling procedure for hyperbolic problems posed on time-dependent curved multi-domains. First, we transform the problem from Cartesian to boundary-conforming curvilinear coordinates and apply the energy method to derive well-posed and conservative interface conditions. Next, we discretize the problem in space and time by employing finite difference operators that satisfy a summation-by-parts rule. The interface condition is imposed weakly using a penalty formulation. We show how to formulate the penalty operators such that the coupling procedure is automatically adjusted to the movements and deformations of the interface, while both stability and conservation conditions are respected. The developed techniques are illustrated by performing numerical experiments on the linearized Euler equations and the Maxwell equations. The results corroborate the stability and accuracy of the fully discrete approximations.

    The full text will be freely available from 2019-03-14 10:31
  • 37.
    Eklund, Anders
    et al.
    Linköping University, Department of Biomedical Engineering, Medical Informatics. Linköping University, Center for Medical Image Science and Visualization (CMIV). Linköping University, The Institute of Technology.
    Andersson, Mats
    Linköping University, Department of Biomedical Engineering, Medical Informatics. Linköping University, Center for Medical Image Science and Visualization (CMIV). Linköping University, The Institute of Technology.
    Knutsson, Hans
    Linköping University, Department of Biomedical Engineering, Medical Informatics. Linköping University, Center for Medical Image Science and Visualization (CMIV). Linköping University, The Institute of Technology.
    A Functional Connectivity Inspired Approach to Non-Local fMRI Analysis2012In: Proceedings of the 19th IEEE International Conference on Image Processing (ICIP), 2012, IEEE conference proceedings, 2012, 1245-1248 p.Conference paper (Other academic)
    Abstract [en]

    We propose non-local analysis of functional magnetic resonanceimaging (fMRI) data in order to detect more brain activity.Our non-local approach combines the ideas of regularfMRI analysis with those of functional connectivity analysis,and was inspired by the non-local means algorithm thatcommonly is used for image denoising. We extend canonicalcorrelation analysis (CCA) based fMRI analysis to handlemore than one activity area, such that information fromdifferent parts of the brain can be combined. Our non-localapproach is compared to fMRI analysis by the general linearmodel (GLM) and local CCA, by using simulated as well asreal data.

  • 38.
    Eliasson, Peter
    et al.
    FOI, Swedish Defence Research Agency, SE-16490 Stockholm, Sweden.
    Lundquist, Tomas
    Linköping University, Department of Mathematics, Computational Mathematics. Linköping University, Faculty of Science & Engineering.
    Nordström, Jan
    Linköping University, Department of Mathematics, Computational Mathematics. Linköping University, Faculty of Science & Engineering.
    A global time integration approach for realistic unsteady flow computations2016Conference paper (Refereed)
    Abstract [en]

    A novel time integration approach is explored for unsteady flow computations. It is a multi-block formulation in time where one solves for all time levels within a block simultaneously. The time discretization within a block is based on the summation-by-parts (SBP) technique in time combined with the simultaneous-approximation-term (SAT) technique for imposing the initial condition. The approach is implicit, unconditionally stable and can be made high order accurate in time. The implicit system is solved by a dual time stepping technique. The technique has been implemented in a flow solver for unstructured grids and applied to an unsteady flow problem with vortex shedding over a cylinder. Four time integration approaches being 2nd to 5th order accurate in time are evaluated and compared to the conventional 2nd order backward difference (BDF2) method and a 4th order diagonally implicit Runge-Kutta scheme (ESDIRK64). The obtained orders of accuracy are higher than expected and correspond to the accuracy in the interior of the blocks, up to 8th order accuracy is obtained. The influence on the accuracy from the size of the time blocks is small. Smaller blocks are computationally more efficient though, and the efficiency increases with increased accuracy of the SBP operator and reduced size of time steps. The most accurate scheme, with a small time step and block size, is approximately as efficient as the ESDIRK64 scheme. There is a significant potential for improvements ranging from convergence acceleration techniques in dual time, alternative initialization of time blocks, and by introducing smaller time blocks based on alternative SBP operators.

  • 39.
    Eklund, Anders
    et al.
    Linköping University, Department of Biomedical Engineering, Medical Informatics. Linköping University, Center for Medical Image Science and Visualization (CMIV). Linköping University, The Institute of Technology.
    Friman, Ola
    Fraunhofer Mevis, Bremen, Germany.
    Andersson, Mats
    Linköping University, Department of Biomedical Engineering, Medical Informatics. Linköping University, Center for Medical Image Science and Visualization (CMIV). Linköping University, The Institute of Technology.
    Knutsson, Hans
    Linköping University, Department of Biomedical Engineering, Medical Informatics. Linköping University, Center for Medical Image Science and Visualization (CMIV). Linköping University, The Institute of Technology.
    A GPU accelerated interactive interface for exploratory functional connectivity analysis of FMRI data2011In: Image Processing (ICIP), 2011, IEEE , 2011, 1589-1592 p.Conference paper (Refereed)
    Abstract [en]

    Functional connectivity analysis is a way to investigate how different parts of the brain are connected and interact. A common measure of connectivity is the temporal correlation between a reference voxel time series and all the other time series in a functional MRI data set. An fMRI data set generally contains more than 20,000 within-brain voxels, making a complete correlation analysis between all possible combinations of voxels heavy to compute, store, visualize and explore. In this paper, a GPU-accelerated interactive tool for investigating functional connectivity in fMRI data is presented. A reference voxel can be moved by the user and the correlations to all other voxels are calculated in real-time using the graphics processing unit (GPU). The resulting correlation map is updated in real-time and visualized as a 3D volume rendering together with a high resolution anatomical volume. This tool greatly facilitates the search for interesting connectivity patterns in the brain.

  • 40.
    Norin, Anna
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Science and Technology.
    Andersson, Tobias
    Linköping University, The Institute of Technology. Linköping University, Department of Science and Technology.
    Värbrand, Peter
    Linköping University, The Institute of Technology. Linköping University, Department of Science and Technology.
    Yuan, Di
    Linköping University, The Institute of Technology. Linköping University, Department of Science and Technology, Communications and Transport Systems.
    A GRASP Heuristic for Scheduling De-icing trucks at Stockholm Arlanda Airport2007In: 6th Eurocontrol Innovative Research Workshop and Exhibition,2007, 2007Conference paper (Other academic)
    Abstract [en]

    It is a fact that the most delays in the Air Transportation System (ATS) today occur at the airport. One reason for this is the large number of actors operating at the airport and the scarcity of communication between them and other parts of the ATS. Airport Logistics is a concept developed to survey all the flows of ehicles, people, material and information, which can be found on and around the airport. The objective is to increase efficiency, where one part is to decrease the delays. As an initial step, the turn-around process is analysed and an optimization model for the planning of de-icing trucks is implemented. The model shows that large savings can be made both by reducing the travelling distances for the trucks and reducing the delays the de-icing process is causing the ATS. However, most important is the advantage of having a plan for how the de-icing trucks should be utilized, something that is missing today.  

  • 41.
    Pettersson, Johanna
    et al.
    Linköping University, Department of Biomedical Engineering, Medical Informatics. Linköping University, Center for Medical Image Science and Visualization (CMIV). Linköping University, The Institute of Technology.
    Knutsson, Hans
    Linköping University, Department of Biomedical Engineering, Medical Informatics. Linköping University, Center for Medical Image Science and Visualization (CMIV). Linköping University, The Institute of Technology.
    Nordqvist, Per
    Melerit Medical AB .
    Borga, Magnus
    Linköping University, Department of Biomedical Engineering, Medical Informatics. Linköping University, Center for Medical Image Science and Visualization (CMIV). Linköping University, The Institute of Technology.
    A hip surgery simulator based on patient specific models generated by automatic segmentation2006In: Medicine Meets Virtual Reality 14: Accelerating Change in Healthcare: Next Medical Toolkit / [ed] James D Westwood; et al, Amsterdam, Nederländerna: IOS Press, 2006, 431-436 p.Conference paper (Refereed)
    Abstract [en]

    The use of surgical simulator systems for education and preoperative planning is likely to increase in the future. A natural course of development of these systems is to incorporate patient specific anatomical models. This step requires some kind of segmentation process in which the different anatomical parts are extracted. Anatomical datasets are, however, usually very large and manual processing would be too demanding. Hence, automatic, or semi-automatic, methods to handle this step are required. The framework presented in this paper uses nonrigid registration, based on the morphon method, to automatically segment the hip anatomy and generate models for a hip surgery simulator system.

  • 42.
    Woltjer, Rogier
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Mechanical Engineering, Industrial Ergonomics.
    McGee, Kevin
    Linköping University, The Institute of Technology. Linköping University, Department of Computer and Information Science, ASLAB - Application Systems Laboratory.
    A Joint Subsumption Architecture as a Framework to Address Dynamic Human-Machine Function Allocation2004In: SIMsafe2004,2004, 2004Conference paper (Refereed)
    Abstract [en]

    The various models and simulations of automobile driving that have been suggested over time have differential explanatory and predictive power. Some address the processes within the driver, others have the joint system of driver and car as a unit of analysis. One of the particular limitations that is not well-addressed in these models is the prospect of semi-autonomy that currently emerges when technology enables the car to take over parts of the driving task. The utility of combined human-machine subsumption architectures in semi-autonomous wheelchair control suggests that the joint subsumption architecture has the potential to address the issue of semi-autonomy in motor vehicles generally. In order to address semi-autonomy in simulated driving, we have explored a joint subsumption model in a 2D top-down view driving simulation in which the human controller is a layer in a subsumption control architecture, extended with a behaviour coordination mechanism that combines simple command fusion with priority-based arbitration. Joint human-machine subsumption seems to be a useful architecture to conduct research concerning semi-autonomy. Several possibilities for future research are sketched.

  • 43.
    Carlborg, Per
    et al.
    Linköping University, Department of Management and Engineering, Industrial Marketing and Industrial Economics. Linköping University, The Institute of Technology.
    Kindström, Daniel
    Linköping University, Department of Management and Engineering, Industrial Marketing and Industrial Economics. Linköping University, The Institute of Technology.
    Kowalkowski, Christian
    Linköping University, Department of Management and Engineering, Industrial Marketing and Industrial Economics. Linköping University, The Institute of Technology.
    A lean approach for service productivityimprovements: Synergy or oxymoron?Manuscript (preprint) (Other academic)
    Abstract [en]

    Purpose: Service productivity has received increasing attention as service continues to cover greater parts of the economy. And as the competition increases, the need to look at service productivity becomes increasingly important. However, there is scant research on developing services that are both efficient and with high customer satisfaction. The present study aims to address this topic by conceptualizing the applicability of lean principles to service.

    Design/methodology/approach: The paper presents a conceptual analysis of the six most commonly used lean principles in manufacturing and their applicability in a service context for different types of services.

    Findings: The study suggests promising synergies, as well as important obstacles, for applying lean principles in services. Standardizing services and increasing reliability in service processes through lean principles can increase efficiency. However, the active role of the customer in certain services along with simultaneously high diversity makes it increasingly difficult to apply lean principles. Also, customer satisfaction must be considered when improving service productivity, otherwise the positive long-term effects of a lean approach in service will be absent.

    Practical implications: The findings are useful for organizations aiming to improve their service productivity. Particularly, lean principles are invaluable to increase the efficiency for services with low diversity and low customer participation. This paper suggests a direction for the proper use of lean  principles for different service types, and how efficiency and customer satisfaction is affected through a lean approach.

    Originality/Value: The study contributes to the research on service productivity. The study also contributes to continuing discussions on prototypic characteristics of service and manufacturing orientations.

  • 44.
    Håkansson, Jennie
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Zoology . Linköping University, The Institute of Technology.
    Jensen, Per
    Linköping University, Department of Physics, Chemistry and Biology, Zoology . Linköping University, The Institute of Technology.
    A longitudinal study of antipredator behaviour in four successive generations of two populations of captive red junglefowl2008In: Applied Animal Behaviour Science, ISSN 0168-1591, E-ISSN 1872-9045, Vol. 114, no 3-4, 409-418 p.Article in journal (Refereed)
    Abstract [en]

    Conservation breeding and reintroduction into the wild can only be an effective management tool if behaviours essential for a life in the wild are maintained in captivity. The aim of this study was to investigate how a protected captive environment influences antipredator behaviour over generations. The red junglefowl (Gallus gallus) was used as a case study. Birds from two different captive populations were followed over four generations. In the last three generations, all birds were hatched and reared in the same indoor settings. Antipredator behaviour was measured in each generation in a standardised test where the birds were exposed to a simulated predator attack. The test was divided into three parts: pre-exposure period, exposure and post-exposure periods. There was an interaction effect between Population and generation (F-3.129 = 4.84, P < 0.01) on behaviour during the pre-exposure period, suggesting that the birds "baseline" agitation level may have been altered differently in the two populations. Population differences were also found during the post-exposure period but the populations tended to become more similar over successive generations in their behaviour after the exposure. Furthermore, there were significant effects of generation (H (d.f. = 1, N = 137) = 10.94, P < 0.05) as well as population (H (d.f. = 1, N = 137) = 5.17, P < 0.05) on the immediate reaction to the simulated predator attack. In conclusion, over four successive generations, the two populations altered their antipredator behaviour and tended to become more similar. This study shows that antipredator behaviour may change over generations in a captive environment. This is likely to be one of the most crucial factors for successful reintroduction into the wild and hence, it is a very important aspect to consider for conservation breeding.

  • 45.
    Gustafsson, Daniel
    et al.
    Linköping University, Department of Management and Engineering.
    Johansson, Mikael
    Linköping University, Department of Management and Engineering.
    A Material Flow Evaluation at Scania Production Slupsk S.P.S2007Independent thesis Basic level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    This master’s thesis is performed at Department of Management and Engineering Linköping University, for Scania Omni at Scania Production Slupsk (S.P.S). Omni is responsible for development, manufacturing and marketing of city, suburban and intercity buses. After acquisition of the production unit in Slupsk in 2002 lower production cost per bus is possible. But without control over the organisation costs are rising due to late delivery fees and high stock levels. At the outset, the thesis included three clearly defined objectives:

    - Map the present situation at Scania Production Slupsk regarding material flow from supplier to assembly line including a part and storage analysis.

    - Benchmark the current routines at Scania Production Slupsk with other successful companies. Furthermore, conduct literature research in order to find theories and philosophies that support problem analysis and thesis solution.

    - Develop standard routines for material control methods (MCM) and material supply methods (MSM).

    A complimentary objective is to work as a catalyst during the time of the thesis.

    The mapping of the present situation showed that MCM and MSM are very tight connected to each other. It was questioned whether this structure was the best way to manage the material flow. After a parts and storage analysis, material was divided into different segments depending of price, consumption and movement.

    The benchmarking studies showed different ways to manage the material flow. Implementation of unit load, kanban and clear defined interface between departments showed potential to improve the material handling and increase effectiveness.

    New routines and part segment definitions described in a logistics manual (Appendix I) were made align with a comparison between previous and recommended definitions.

    The result showed that some parts needs to be controlled differently. Primary recommendations are that logistics manual shall be used when new parts are introduced into the Scala system. Responsible personnel are suppose to give suggestion concerning decision making of MCM and MSM and with help of the logistics manual the work can be more efficient, resulting in a material flow that is flexible and have potential for improvements.

    Secondary, to avoid material handling to some extent implementation of two-bin system is recommended. Additional recommendations regarding two-bin system is to handle material according to unit load, which enable FIFO, traceability and higher turn over rate

  • 46.
    Sunnaker, Mikael
    et al.
    Fraunhofer Chalmers Research Centre for Industrial Math.
    Cedersund, Gunnar
    Linköping University, Department of Clinical and Experimental Medicine, Cell Biology. Linköping University, Faculty of Health Sciences.
    Jirstrand, Mats
    Fraunhofer Chalmers Research Centre for Industrial Math.
    A method for zooming of nonlinear models of biochemical systems2011In: BMC Systems Biology, ISSN 1752-0509, Vol. 5, no 140Article in journal (Refereed)
    Abstract [en]

    Background: Models of biochemical systems are typically complex, which may complicate the discovery of cardinal biochemical principles. It is therefore important to single out the parts of a model that are essential for the function of the system, so that the remaining non-essential parts can be eliminated. However, each component of a mechanistic model has a clear biochemical interpretation, and it is desirable to conserve as much of this interpretability as possible in the reduction process. Furthermore, it is of great advantage if we can translate predictions from the reduced model to the original model. less thanbrgreater than less thanbrgreater thanResults: In this paper we present a novel method for model reduction that generates reduced models with a clear biochemical interpretation. Unlike conventional methods for model reduction our method enables the mapping of predictions by the reduced model to the corresponding detailed predictions by the original model. The method is based on proper lumping of state variables interacting on short time scales and on the computation of fraction parameters, which serve as the link between the reduced model and the original model. We illustrate the advantages of the proposed method by applying it to two biochemical models. The first model is of modest size and is commonly occurring as a part of larger models. The second model describes glucose transport across the cell membrane in bakers yeast. Both models can be significantly reduced with the proposed method, at the same time as the interpretability is conserved. less thanbrgreater than less thanbrgreater thanConclusions: We introduce a novel method for reduction of biochemical models that is compatible with the concept of zooming. Zooming allows the modeler to work on different levels of model granularity, and enables a direct interpretation of how modifications to the model on one level affect the model on other levels in the hierarchy. The method extends the applicability of the method that was previously developed for zooming of linear biochemical models to nonlinear models.

  • 47.
    Stenfelt, Stefan PY
    et al.
    Chalmers University of Technology.
    Håkansson, Bo EV
    Chalmers University of Technology.
    A miniaturized artificial mastoid using a skull simulator1998In: Scandinavian Audiology, ISSN 0105-0397, Vol. 27, no 2, 67-76 p.Article in journal (Refereed)
    Abstract [en]

    A miniaturized artificial mastoid of size and weight that allow calibration and measurement of bone conduction hearing aids in a conventional audiometric soundproof box has been developed. Its level of mechanical impedance corresponds to the standard IEC 373 (1990) within the frequency range 250 Hz to 8 kHz. The miniaturized artificial mastoid consists of three parts: coupler, skull simulator (TU-1000), and an external electrical correction filter. The soupier is a highly damped mass-spring system designed to give the miniaturized artificial mastoid mechanical impedance in accordance with the standard IEC 373 (1990). It was found that the miniaturized artificial mastoid yielded results that are in correspondence with results obtained with the Bruel and Kjaer type 4930 artificial mastoid for frequencies above 350 Hz. Thus, at these frequencies, the miniaturized artificial mastoid can be used for audiometer calibration as well as measurement of bone conduction hearing aids.

  • 48.
    Edlund, Ulf
    et al.
    Linköping University, Department of Management and Engineering, Mechanics . Linköping University, The Institute of Technology.
    Schmidt, Peter
    Linköping University, Department of Management and Engineering, Mechanics . Linköping University, The Institute of Technology.
    Roguet , E
    ENSMA, France.
    A model of an adhesively bonded joint with elastic-plastic adherends and a softening adhesive2009In: Computer Methods in Applied Mechanics and Engineering, ISSN 0045-7825, Vol. 198, no 5-8, 740-752 p.Article in journal (Refereed)
    Abstract [en]

    This paper deals with the generalization of a model of an adhesively bonded joint with the aim to allow elastic-plastic adherends. In the model of the joint that we extend, the thinness of the bodies and the low Youngs modulus of the adhesive were used to obtain a simplified model where the parts are described as material surfaces. We formulate an elastic-plastic material model with isotropic hardening expressed in the generalized stress and strain measures used for the surface description of the joint. The finite element formulation and the numerical treatment of the constitutive law are discussed. Numerical results showing the accuracy of the proposed treatment of the adherends are presented. Two failure load computations, using a softening material model for the adhesive, are presented and compared with experiments. The results show the importance of taking into account potential plastic deformations in the adherends in failure load computations.

  • 49.
    Fernández del Río, Lia
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Applied Optics . Linköping University, The Institute of Technology.
    Arwin, Hans
    Linköping University, Department of Physics, Chemistry and Biology, Applied Optics . Linköping University, The Institute of Technology.
    Landin, Jan
    Linköping University, Department of Physics, Chemistry and Biology, Applied Optics . Linköping University, Department of Physics, Chemistry and Biology, Biology. Linköping University, The Institute of Technology.
    Magnusson, Roger
    Linköping University, Department of Physics, Chemistry and Biology, Applied Optics . Linköping University, The Institute of Technology.
    Järrendahl, Kenneth
    Linköping University, Department of Physics, Chemistry and Biology, Applied Optics . Linköping University, The Institute of Technology.
    A Mueller Matrix Spectroscopic Ellipsometry Study of Scarab Beetles of the Chrysina Genus2012Conference paper (Other academic)
    Abstract [en]

    The attractive shiny metallic colour of jewel scarabs is originating from the structure of the exoskeleton.For some directions and wavelengths of the incident light this structure will also cause the reflectedlight to have a large ellipticity (near-circular polarization). This is due to that the exoskeleton is ahelicoidal structure, formed by layers of chitin molecules. The reflected light is most commonly lefthandedpolarized but right-handed polarization is also observed. In this work six species of Scarabbeetles from the Chrysina genus are investigated. The complete Mueller-matrix is measured with adual rotating compensator ellipsometer (RC2, J.A.Woollam Co., Inc.). The results are presented ascontour plots where we represent different parameters as a function of incidence angle 2[25; 75]and wavelength 2[240; 1000]nm of the incident beam. Parameters of particular interest are the m41element of the Mueller-matrix, which is related to the circular polarization behaviour, the degree ofpolarization, the ellipticity and the absolute value of the azimuth angle. From ocular observationsthrough left- and right-circularly polarizing filters all specimens showed clear polarization effects interms of colour changes. However, the Mueller matrix ellipsometry measurements showed two generaltypes of polarization behaviour depending on the studied species. Chrysina macropus and Chrysinaperuviana had a smaller range of m41 values around zero. Much larger m41 variations were observedfor Chrysina argenteola, Chrysina chrysargyrea and Chrysina resplendens. Chrysina gloriosa hadboth types of polarization behaviour depending on if the measurements where made on the green orgolden parts of this striped beetle. Comparisons among samples of beetles from the same species wereconducted. For instance, different specimens of Chrysina resplendens show rather large differences inthe polarization response whereas specimens of Chrysina chrysargyrea showed very similar polarizationbehaviour. All studied specimens did in some sense reflect both right- and left-handed polarizedlight. In many cases very high ellipticities (near-circular polarization states) were observed. Modelsof structures generating the observed polarization effects as well as biological aspects will also bediscussed.Figure 257: Three pictures of C. chrysargyrea from left to right taken with aleft-circular polarizer, no filters and with a right-circular polarizer in front of thecamera. Two contour plots of m41 for C. chrysargyrea showing a large region withleft-handed near-circular polarization and C. resplendens showing a large regionwith right-handed near-circular polarization.

  • 50.
    Li, Xueru
    et al.
    Tsinghua University, Beijing, China.
    Björnson, Emil
    Linköping University, Department of Electrical Engineering, Communication Systems. Linköping University, Faculty of Science & Engineering.
    Larsson, Erik G
    Linköping University, Department of Electrical Engineering, Communication Systems. Linköping University, Faculty of Science & Engineering.
    Zhou, Shidong
    Tsinghua University, Beijing, China.
    Wang, Jing
    Tsinghua University, Beijing, China.
    A Multi-cell MMSE Detector for Massive MIMO Systems and New Large System Analysis2015In: 2015 IEEE Global Communications Conference, GLOBECOM 2015, Institute of Electrical and Electronics Engineers (IEEE), 2015, 1-6 p.Conference paper (Refereed)
    Abstract [en]

    In this paper, a new multi-cell MMSE detector is proposed for massive MIMO systems. Let K and B denote the number of users in each cell and the number of available pilot sequences in the network, respectively, with B = βK, where β ≥ 1 is called the pilot reuse factor. The novelty of the multi-cell MMSE detector is that it utilizes all B channel directions that can be estimated locally at a base station, so that intra-cell interference, parts of the inter-cell interference and the noise can all be actively suppressed, while conventional detectors only use the K intra-cell channels. Furthermore, in the large- system limit, a deterministic equivalent expression of the uplink SINR for the proposed multi-cell MMSE is derived. The expression is easy to compute and accounts for power control for the pilot and payload, imperfect channel estimation and arbitrary pilot allocation. Numerical results show that significant sum spectral efficiency gains can be obtained by the multi-cell MMSE over the conventional single-cell MMSE and the recent multi-cell ZF, and the gains become more significant as β and/or K increases. Furthermore, the deterministic equivalent is shown to be very accurate even for relatively small system dimensions.

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