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  • 201.
    Bigun, Josef
    et al.
    Högskolan i Halmstad, Sektionen för Informationsvetenskap, Data– och Elektroteknik (IDE), Halmstad Embedded and Intelligent Systems Research (EIS).
    Bigun, Tomas
    TietoEnator ArosTech AB, Linköping.
    Symmetry derivatives of Gaussians illustrated by cross tracking2001Rapport (Annet vitenskapelig)
    Abstract [en]

    We propose a family of complex differential operators, symmetry derivatives, for pattern recognition in images. We present three theorems on their properties as applied to Gaussians. These show that all orders of symmetry derivatives of Gaussians yield compact expressions obtained by replacing the original differential polynomial with an ordinary polynomial. Just like Gaussians, the symmetry derivatives of Gaussians are (form) invariant to Fourier transform, that is they are rescaled versions of the original. As a result, the symmetry derivatives of Gaussians are closed under the convolution operator, i.e. they map on a member of the family when convolved with each other. Since Gaussians are utilized extensively in image processing, the revealed properties have practical consequences, e.g. when designing filters and filtering schemes that are unbiased w.r.t. orientation (isotropic). A use of these results is illustrated by an application: tracking the cross markers in long image sequences from vehicle crash tests. The implementation and the results of this application are discussed in terms of the theorems presented, along with conclusions.

  • 202.
    Bigun, Josef
    et al.
    Högskolan i Halmstad, Sektionen för Informationsvetenskap, Data– och Elektroteknik (IDE), Halmstad Embedded and Intelligent Systems Research (EIS).
    Bigun, Tomas
    TietoEnator ArosTech, Linköping, Sweden.
    Nilsson, Kenneth
    Högskolan i Halmstad, Sektionen för Informationsvetenskap, Data– och Elektroteknik (IDE), Halmstad Embedded and Intelligent Systems Research (EIS).
    Orientation fields filtering by derivatives of a Gaussian2003Inngår i: Proceedings of the 13th Scandinavian Conference on Image Analysis (SCIA 2003), Halmstad, Sweden, Date: jun 29-jul 02, 2003, Berlin: Springer Berlin/Heidelberg, 2003, Vol. LNCS-2749, s. 19-27Konferansepaper (Annet vitenskapelig)
    Abstract [en]

    We suggest a set of complex differential operators, symmetry derivatives, that can be used for matching and pattern recognition. We present results on the invariance properties of these. These show that all orders of symmetry derivatives of Gaussians yield a remarkable invariance : they are obtained by replacing the original differential polynomial with the same polynomial but using ordinary scalars. Moreover, these functions are closed under convolution and they are invariant to the Fourier transform. The revealed properties have practical consequences for local orientation based feature extraction. This is shown by two applications: i) tracking markers in vehicle tests ii) alignment of fingerprints.

  • 203.
    Bigun, Josef
    et al.
    Högskolan i Halmstad, Sektionen för Informationsvetenskap, Data– och Elektroteknik (IDE), Halmstad Embedded and Intelligent Systems Research (EIS).
    Bigun, Tomas
    TietoEnator AB, Storg. 3, 58223 Linköping, Sweden.
    Nilsson, Kenneth
    Högskolan i Halmstad, Sektionen för Informationsvetenskap, Data– och Elektroteknik (IDE), Halmstad Embedded and Intelligent Systems Research (EIS).
    Recognition by symmetry derivatives and the generalized structure tensor2004Inngår i: IEEE Transaction on Pattern Analysis and Machine Intelligence, ISSN 0162-8828, E-ISSN 1939-3539, Vol. 26, nr 12, s. 1590-1605Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We suggest a set of complex differential operators that can be used to produce and filter dense orientation (tensor) fields for feature extraction, matching, and pattern recognition. We present results on the invariance properties of these operators, that we call symmetry derivatives. These show that, in contrast to ordinary derivatives, all orders of symmetry derivatives of Gaussians yield a remarkable invariance: they are obtained by replacing the original differential polynomial with the same polynomial, but using ordinary coordinates x and y corresponding to partial derivatives. Moreover, the symmetry derivatives of Gaussians are closed under the convolution operator and they are invariant to the Fourier transform. The equivalent of the structure tensor, representing and extracting orientations of curve patterns, had previously been shown to hold in harmonic coordinates in a nearly identical manner. As a result, positions, orientations, and certainties of intricate patterns, e.g., spirals, crosses, parabolic shapes, can be modeled by use of symmetry derivatives of Gaussians with greater analytical precision as well as computational efficiency. Since Gaussians and their derivatives are utilized extensively in image processing, the revealed properties have practical consequences for local orientation based feature extraction. The usefulness of these results is demonstrated by two applications:

    1. tracking cross markers in long image sequences from vehicle crash tests and
    2. alignment of noisy fingerprints.
  • 204.
    Bigun, Josef
    et al.
    Högskolan i Halmstad, Akademin för informationsteknologi, Halmstad Embedded and Intelligent Systems Research (EIS).
    Choy, Kwok
    Högskolan i Halmstad.
    Olsson, Henrik
    Högskolan i Halmstad.
    Evidence on skill differences of women and men concerning face recognition2001Inngår i: Audio- and video-based biometric person authentication: Third International Conference, AVBPA 2001, Halmstad, Sweden, June 6-8, 2001 : proceedings / [ed] Josef Bigun, Fabrizio Smeraldi, (eds.), Berlin: Springer, 2001, s. 44-51Konferansepaper (Annet vitenskapelig)
    Abstract [en]

    We present a cognitive study regarding face recognition skills of women and men. The results reveal that there are in the average sizable skill differences between women and men in human face recognition. The women had higher correct answer frequencies then men in all face recognition questions they answered. In difficult questions, those which had fewer correct answers than other questions, the performance of the best skilled women were remarkably higher than the best skilled men. The lack of caricature type information (high spatial frequencies) hampers the recognition task significantly more than the lack of silhouette and shading (low spatial frequencies) information, according to our findings. Furthermore, the results confirmed the previous findings that hair style and facial expressions degrades the face recognition performance of humans significantly. The reported results concern 1838 individuals and the study was effectuated by means of Internet.

  • 205.
    Bigun, Josef
    et al.
    Högskolan i Halmstad, Sektionen för Informationsvetenskap, Data– och Elektroteknik (IDE), Halmstad Embedded and Intelligent Systems Research (EIS).
    Choy, Kwok-wai
    Olsson, Henrik
    Evidence on skill differences of women and men concerning face recognition2001Rapport (Annet vitenskapelig)
    Abstract [en]

    We present a cognitive study regarding face recognition skills of women and men. The results reveal that there are in the average sizable skill differences between women and men in human face recognition. The women had higher correct answer frequencies then men in all face recognition questions they answered. In difficult questions, those which had fewer correct answers than other questions, the performance of the best skilled women were remarkably higher than the best skilled men. The lack of caricature type information (high spatial frequencies) hampers the recognition task significantly more than the lack of silhouette and shading (low spatial frequencies) information, according to our findings. Furthermore, the results confirmed the previous findings that hair style and facial expressions degrades the face recognition performance of humans significantly. The reported results concern 1838 individuals and the study was effectuated by means of Internet.

  • 206.
    Bigun, Josef
    et al.
    Högskolan i Halmstad, Akademin för informationsteknologi, Halmstad Embedded and Intelligent Systems Research (EIS), Intelligenta system (IS-lab).
    Fierrez-Aguilar, J.
    Universidad Politecnica de Madrid, Spain.
    Ortega-Garcia, J.
    Universidad Politecnica de Madrid, Spain.
    Gonzalez-Rodriguez, J.
    Universidad Politecnica de Madrid, Spain.
    Combining Biometric Evidence for Person Authentication2005Inngår i: Advanced Studies in Biometrics: Summer School on Biometrics, Alghero, Italy, June 2-6, 2003 / [ed] Tistarelli, Massimo; Bigun, Josef; Grosso, Enrico, Berlin: Springer Berlin/Heidelberg, 2005, s. 1-18Konferansepaper (Annet vitenskapelig)
    Abstract [en]

    Humans are excellent experts in person recognition and yet they do not perform excessively well in recognizing others only based on one modality such as single facial image. Experimental evidence of this fact is reported concluding that even human authentication relies on multimodal signal analysis. The elements of automatic multimodal authentication along with system models are then presented. These include the machine experts as well as machine supervisors. In particular, fingerprint and speech based systems will serve as illustration. A signal adaptive supervisor based on the input biometric signal quality is evaluated.

  • 207.
    Bigun, Josef
    et al.
    Högskolan i Halmstad, Sektionen för Informationsvetenskap, Data– och Elektroteknik (IDE), Halmstad Embedded and Intelligent Systems Research (EIS).
    Fiérrez-Aguilar, Julián
    Universidad Autonoma de Madrid, Biometric Recognition Group - ATVS, Madrid, Spain.
    Ortega-García, Javier
    Universidad Autonoma de Madrid, Biometric Recognition Group - ATVS, Madrid, Spain.
    González-Rodríguez, Joaquín
    Universidad Autonoma de Madrid, Biometric Recognition Group - ATVS, Madrid, Spain.
    Multimodal biometric authentication using quality signals in mobile communications2003Inngår i: Proceedings - 12th International Conference on Image Analysis and Processing, ICIAP 2003, Los Alamitos, USA: IEEE Computer Society, 2003, s. 2-11Konferansepaper (Annet vitenskapelig)
    Abstract [en]

    The elements of multimodal authentication along with system models are presented. These include the machine experts as well as machine supervisors. In particular fingerprint and speech based systems will serve as illustration of a mobile authentication application. A novel signal adaptive supervisor, based on the input biometric signal quality is evaluated. Experimental results on data collected from mobile telephones are reported demonstrating the benefits of the proposed scheme. © 2003 IEEE.

  • 208.
    Bigun, Josef
    et al.
    Högskolan i Halmstad, Akademin för informationsteknologi, Halmstad Embedded and Intelligent Systems Research (EIS), Intelligenta system (IS-lab).
    Fronthaler, Hartwig
    Högskolan i Halmstad, Akademin för informationsteknologi, Halmstad Embedded and Intelligent Systems Research (EIS).
    Kollreider, Klaus
    Högskolan i Halmstad, Akademin för informationsteknologi, Halmstad Embedded and Intelligent Systems Research (EIS).
    Assuring liveness in biometric identity authentication by real-time face tracking2004Inngår i: CIHSPS 2004: proceedings of the 2004 IEEE International Conference on Computational Intelligence for Homeland Security and Personal Safety : S. Giuliano, Venice, Italy, 21-22 July 2004 / [ed] IEEE, Piscataway, N.J.: IEEE Press, 2004, s. 104-111Konferansepaper (Fagfellevurdert)
    Abstract [en]

    A system that combines real-time face tracking as well as the localization of facial landmarks in order to improve the authenticity of fingerprint recognition is introduced. The intended purpose of this application is to assist in securing public areas and individuals, in addition to enforce that the collected sensor data in a multi modal person authentication system originate front present persons, i.e. the system is not under a so called play back attack. Facial features are extracted with the help of Gabor filters and classified by SVM experts. For real-time performance, selected points from a retinotopic grid are used to form regional face models. Additionally only a subset of the Gabor decomposition is used for different face regions. The second modality presented is texture-based fingerprint recognition, exploiting linear symmetry. Experimental results on the proposed system are presented.

  • 209.
    Bigun, Josef
    et al.
    Högskolan i Halmstad, Sektionen för Informationsvetenskap, Data– och Elektroteknik (IDE), Halmstad Embedded and Intelligent Systems Research (EIS).
    Gustavsson, TomasChalmers University of Technology, Department of Signals and Systems, Gothenburg, Sweden.
    Image analysis: 13th Scandinavian Conference, SCIA 2003, Halmstad, Sweden, June 29-July 2, 2003, Proceedings2003Konferanseproceedings (Annet vitenskapelig)
    Abstract [en]

    This book constitutes the refeered proceedings of the 13th Scandinavian Conference on Image Analysis, SCIA 2003, held in Halmstad, Sweden in June/July 2003.The 148 revised full papers presented together with 6 invited contributions were carefully reviewed and selected for presentation. The papers are organized in topical sections on feature extraction, depth and surface, shape analysis, coding and representation, motion analysis, medical image processing, color analysis, texture analysis, indexing and categorization, and segmentation and spatial grouping.

  • 210.
    Bigun, Josef
    et al.
    Högskolan i Halmstad, Sektionen för Informationsvetenskap, Data– och Elektroteknik (IDE), Halmstad Embedded and Intelligent Systems Research (EIS).
    Karlsson, Stefan M.
    Högskolan i Halmstad, Sektionen för Informationsvetenskap, Data– och Elektroteknik (IDE), Halmstad Embedded and Intelligent Systems Research (EIS).
    Histogram of directions by the structure tensor2011Inngår i: Proceedings of the 4th International Symposium on Applied Sciences in Biomedical and Communication Technologies, New York, NY: Association for Computing Machinery (ACM), 2011Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Many low-level features, as well as varying methods of extraction and interpretation rely on directionality analysis (for example the Hough transform, Gabor filters, SIFT descriptors and the structure tensor). The theory of the gradient based structure tensor (a.k.a. the second moment matrix) is a very well suited theoretical platform in which to analyze and explain the similarities and connections (indeed often equivalence) of supposedly different methods and features that deal with image directionality. Of special interest to this study is the SIFT descriptors (histogram of oriented gradients, HOGs). Our analysis of interrelationships of prominent directionality analysis tools offers the possibility of computation of HOGs without binning, in an algorithm of comparative time complexity.

  • 211.
    Bigun, Josef
    et al.
    Högskolan i Halmstad, Sektionen för Informationsvetenskap, Data– och Elektroteknik (IDE), Halmstad Embedded and Intelligent Systems Research (EIS).
    Malmqvist, Kerstin
    Proceedings: Symposium on image analysis, Halmstad March 7-8, 20002000Konferanseproceedings (Annet vitenskapelig)
  • 212.
    Bigun, Josef
    et al.
    Högskolan i Halmstad, Akademin för informationsteknologi, Halmstad Embedded and Intelligent Systems Research (EIS), CAISR Centrum för tillämpade intelligenta system (IS-lab).
    Mikaelyan, Anna
    Högskolan i Halmstad, Akademin för informationsteknologi, Halmstad Embedded and Intelligent Systems Research (EIS), CAISR Centrum för tillämpade intelligenta system (IS-lab).
    Dense frequency maps by Structure Tensor and logarithmic scale space: application to forensic fingerprintsManuskript (preprint) (Annet vitenskapelig)
    Abstract [en]

    Increasingly, reliable absolute frequency and orientation maps are needed, e.g. for image enhancement. Less studied is however the mutual dependence of both maps, and how to estimate them when none is known initially. We introduce a logarithmic scale space generated by the trace of Structure Tensor to study the relationship. The scale space is non-linear and absolute frequency estimation is reduced to an orientation estimation in it. We show that this offers significant advantages, including construction of efficient estimation methods, using Structure Tensor yielding dense maps of absolute frequency as well as orientation. In fingerprints, both maps can successively improve each other, combined in an image enhancement scheme via Gabor filtering. We verify that the suggested method compares favorably with state of the art, using forensic fingerprints recognition as test bed, and using test images where the ground truth is known. Furthermore, we suggest a novel continuous ridge counting method, relying only on dense absolute frequency and orientation maps, without ridge detection, thinning, etc. We present new evidence that the neighborhoods of the absolute frequency map are useful attributes of minutiae. In experiments, we use public data sets to support the conclusions.

  • 213.
    Bigun, Josef
    et al.
    Högskolan i Halmstad, Akademin för informationsteknologi, Halmstad Embedded and Intelligent Systems Research (EIS), CAISR Centrum för tillämpade intelligenta system (IS-lab).
    Mikaelyan, Anna
    Högskolan i Halmstad, Akademin för informationsteknologi, Halmstad Embedded and Intelligent Systems Research (EIS).
    Frequency map by Structure Tensor in Logarithmic Scale Space and Forensic Fingerprints2016Inngår i: PROCEEDINGS OF 29TH IEEE CONFERENCE ON COMPUTER VISION AND PATTERN RECOGNITION WORKSHOPS, (CVPRW 2016), Piscataway, NJ: IEEE, 2016, s. 204-213, artikkel-id 7789522Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Increasingly, absolute frequency and orientation maps are needed, e.g. for forensics. We introduce a non-linear scale space via the logarithm of trace of the Structure Tensor. Therein, frequency estimation becomes an orientation estimation problem. We show that this offers significant advantages, including construction of efficient isotropic estimations of dense maps of frequency. In fingerprints, both maps are shown to improve each other in an enhancement scheme via Gabor filtering. We suggest a novel continuous ridge counting method, relying only on dense absolute frequency and orientation maps, without ridge detection, thinning, etc. Furthermore, we present new evidence that frequency maps are useful attributes of minutiae. We verify that the suggested method compares favorably with state of the art using forensic fingerprints as test bed, and test images where the ground truth is known. In evaluations, we use public data sets and published methods only.

  • 214.
    Bigun, Josef
    et al.
    Högskolan i Halmstad, Sektionen för Informationsvetenskap, Data– och Elektroteknik (IDE), Halmstad Embedded and Intelligent Systems Research (EIS).
    Smeraldi, FabrizioHögskolan i Halmstad, Sektionen för Informationsvetenskap, Data– och Elektroteknik (IDE).
    Audio- and Video-Based Biometric Person Authentication: Third International Conference, AVBPA 2001 Halmstad, Sweden, June 6–8, 2001 Proceedings2001Konferanseproceedings (Annet vitenskapelig)
    Abstract [en]

    This book constitutes the refereed proceedings of the Third International Conference on Audio- and Video-Based Biometric Person Authentication, AVBPA 2001, held in Halmstad, Sweden in June 2001.The 51 revised papers presented together with three invited papers were carefully reviewed and selected for inclusion in the book. The papers are organized in topical sections on face as biometrics; face image processing; speech as biometrics and speech processing; fingerprints as biometrics; gait as biometrics; and hand, signature, and iris as biometrics.

  • 215.
    Bigun, Josef
    et al.
    Högskolan i Halmstad, Sektionen för Informationsvetenskap, Data– och Elektroteknik (IDE), Halmstad Embedded and Intelligent Systems Research (EIS), Intelligenta system (IS-lab).
    Teferi, Dereje
    Högskolan i Halmstad, Sektionen för Informationsvetenskap, Data– och Elektroteknik (IDE), Halmstad Embedded and Intelligent Systems Research (EIS), Intelligenta system (IS-lab).
    Damascening video databases for evaluation of face tracking and recognition – The DXM2VTS database2007Inngår i: Pattern Recognition Letters, ISSN 0167-8655, E-ISSN 1872-7344, Vol. 28, nr 15, s. 2143-2156Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Performance quantification of biometric systems, such as face tracking and recognition highly depend on the database used for testing the systems. Systems trained and tested on realistic and representative databases evidently perform better. Actually, the main reason for evaluating any system on test data is that these data sets represent problems that systems might face in the real world. However, building biometric video databases with realistic background for testing is expensive especially due to its high demand of cooperation from the side of the participants. For example, XM2VTS database contain thousands of video recorded in a studio from 295 subjects. Recording these subjects repeatedly in public places such as supermarkets, offices, streets, etc., is not realistic. To this end, we present a procedure to separate the background of a video recorded in studio conditions with the purpose to replace it with an arbitrary complex background, e.g., outdoor scene containing motion, to measure performance, e.g., eye tracking. Furthermore, we present how an affine transformation and synthetic noise can be incorporated into the production of the new database to simulate natural noise, e.g. motion blur due to translation, zooming and rotation. The entire system is applied to the XM2VTS database, which already consists of several terabytes of data, to produce the DXM2VTS–Damascened XM2VTS database essentially without an increase in resource consumption, i.e., storage, bandwidth, and most importantly, the time of clients populating the database, and the time of the operators.

  • 216.
    Bigun, Josef
    et al.
    Högskolan i Halmstad, Sektionen för Informationsvetenskap, Data– och Elektroteknik (IDE), Halmstad Embedded and Intelligent Systems Research (EIS).
    Verikas, AntanasHögskolan i Halmstad, Sektionen för Informationsvetenskap, Data– och Elektroteknik (IDE), Halmstad Embedded and Intelligent Systems Research (EIS), Laboratoriet för intelligenta system.
    Proceedings SSBA '09: Symposium on Image Analysis, Halmstad University, Halmstad, March 18-20, 20092009Konferanseproceedings (Annet vitenskapelig)
  • 217.
    Bilstrup, Katrin
    Högskolan i Halmstad, Sektionen för Informationsvetenskap, Data– och Elektroteknik (IDE), Halmstad Embedded and Intelligent Systems Research (EIS).
    A preliminary study of wireless body area networks2008Rapport (Annet vitenskapelig)
    Abstract [en]

    The purpose of this preliminary study is to introduce wireless body area networks (WBAN) to the reader but also to give an understanding of what possibilities and challenges there are when using short range wireless communication in this domain. Up to date, there is no standard specifically intended for low-power WBANs thus a developer is referred to use proprietary solutions which could be demanding to compare and choose. This study tries to provide the reader with the knowledge about important parameters in low-power sensor networks. Energy consumption is the really weak part of a wireless sensor network since the transceiver and other hardware equipment still drain batteries. For example the startup time for a transceiver that has been in power-down mode could consume as much as three times the energy

    as compared when sending the actual bits that invoked the transceiver in first place. The actual application must be the one driving the requirements on the communication. However, the application must be designed with for example the startup time in mind. A sensor network is a true cross-layer design problem where many different areas must meet such as hardware designers, application developers and communication people.

  • 218.
    Bilstrup, Katrin
    Högskolan i Halmstad, Sektionen för Informationsvetenskap, Data– och Elektroteknik (IDE), Halmstad Embedded and Intelligent Systems Research (EIS).
    A survey regarding wireless communication standards intended for a high-speed vehicle environment2007Rapport (Annet vitenskapelig)
    Abstract [en]

    The high velocities and dynamic conditions that a vehicular environment represents introducenew and demanding challenges in the area of wireless communication. Vehicle Alert System(VAS) is a research project at Halmstad University, Sweden, focusing on reliable wirelessvehicle communication. Typical examples of applications for a vehicle alert system are pre-crash warning, communicating slippery road conditions, emergency vehicle routing etc. InVAS a set of application scenarios have been chosen specifically to illustrate as manyinteresting research aspects of a vehicle alert system as possible. The chosen scenarios includeboth vehicle-to-vehicle and vehicle-to-infrastructure communications. Research is conductedon all layers of the communication stack relevant for a vehicle alert system – application,network, data link and the physical layer. From a communication perspective a vehicle alertsystem is characterized by short event-driven control messages that have to be receivedwithout errors in time. This implies that different coding strategies, diversity andretransmission schemes must be used to achieve correctness and robustness against theimpairments of the wireless channel.

    This survey presents and discusses different wireless communication standards as well asproprietary solutions that are intended especially for a high-speed vehicular environment. Since VAS is aiming for real-time wireless communication, the examined standards will beevaluated accordingly. Real-time communication implies that there is an upper bound on thecommunication delay such that if the data never reaches its intended recipient before a certaindeadline this will have a more or less negative impact on the system performance. One of themost important features of a real-time communication system (and perhaps even more crucialin a wireless high-speed vehicular environment) is the medium access method. If it is notdeterministic (i.e., if there exists no upper bound on the delay before a station gets access tothe wireless channel) it is not possible to give guarantees about meeting the deadlines.All currently existing standards, draft specifications and proprietary solutions with explicitintention for being used in a vehicular environment are covered in this survey. In preparationof this document the standard/draft documents themselves have been studied and forproprietary solutions the respective company’s home pages and in some cases articles havebeen used for collecting information. One of the currently most discussed standards is thedraft IEEE 802.11p which has been thoroughly studied here. It inherits features from theQuality of Service amendment IEEE 802.11e and the physical layer supplement IEEE802.11a. The full protocol suite WAVE, also developed by IEEE, incorporates the 802.11p.Other standards, drafts and proprietary solutions that have been studied are IEEE 802.16,IEEE 802.20, flash-OFDM, national DSCR systems, CALM and IEEE 802.21. These systemsrange from being simple RFID-look-a-like DSRC systems to more advanced centralized WMAN standards. It can be concluded that none of the standards or proprietary solutions described in this surveyis suitable for applications such as those considered in the VAS research project. Within thedifferent standards there certainly are features suitable for a vehicle alert system but nostandard totally fit the requirements of VAS. One lacking feature common for all standardsinvestigated is the ability of providing deterministic medium access for vehicle-to-vehiclecommunication.

  • 219.
    Bilstrup, Katrin
    et al.
    Högskolan i Halmstad, Sektionen för Informationsvetenskap, Data– och Elektroteknik (IDE), Halmstad Embedded and Intelligent Systems Research (EIS), Inbyggda system (CERES).
    Böhm, Annette
    Högskolan i Halmstad, Sektionen för Informationsvetenskap, Data– och Elektroteknik (IDE), Halmstad Embedded and Intelligent Systems Research (EIS), Inbyggda system (CERES).
    Lidström, Kristoffer
    Högskolan i Halmstad, Sektionen för Informationsvetenskap, Data– och Elektroteknik (IDE), Halmstad Embedded and Intelligent Systems Research (EIS), Inbyggda system (CERES).
    Jonsson, Magnus
    Högskolan i Halmstad, Sektionen för Informationsvetenskap, Data– och Elektroteknik (IDE), Halmstad Embedded and Intelligent Systems Research (EIS), Inbyggda system (CERES).
    Larsson, Tony
    Högskolan i Halmstad, Sektionen för Informationsvetenskap, Data– och Elektroteknik (IDE), Halmstad Embedded and Intelligent Systems Research (EIS), Inbyggda system (CERES).
    Strandén, Lars
    SP Technical Research Institute of Sweden, Borås, Sweden.
    Zakizadeh, Hossein
    Volvo Technology Corporation, Göteborg, Sweden .
    Vehicle Alert System2007Inngår i: Proceedings of 14th world congress on intelligent transport system (ITS), 2007, s. 2-9Konferansepaper (Fagfellevurdert)
    Abstract [en]

    The Vehicle Alert System (VAS) project focuses on cooperative alert services based on timely and reliable communication under the challenging circumstances pertaining to a highly mobile vehicular network. Through a cross-layer design, we gain the flexibility needed to adapt the system to the individual requirements of three chosen application scenarios that represent different situations where cooperation between vehicles can make a significant impact. The VAS project is a collaboration involving academic as well as industrial partners and the final stage of the project is a demonstrator that implements results from the research.

  • 220.
    Bilstrup, Katrin
    et al.
    Högskolan i Halmstad, Sektionen för Informationsvetenskap, Data– och Elektroteknik (IDE), Halmstad Embedded and Intelligent Systems Research (EIS), Inbyggda system (CERES).
    Böhm, Annette
    Högskolan i Halmstad, Sektionen för Informationsvetenskap, Data– och Elektroteknik (IDE), Halmstad Embedded and Intelligent Systems Research (EIS), Inbyggda system (CERES).
    Lidström, Kristoffer
    Högskolan i Halmstad, Sektionen för Informationsvetenskap, Data– och Elektroteknik (IDE), Halmstad Embedded and Intelligent Systems Research (EIS), Inbyggda system (CERES).
    Jonsson, Magnus
    Högskolan i Halmstad, Sektionen för Informationsvetenskap, Data– och Elektroteknik (IDE), Halmstad Embedded and Intelligent Systems Research (EIS), Inbyggda system (CERES).
    Larsson, Tony
    Högskolan i Halmstad, Sektionen för Informationsvetenskap, Data– och Elektroteknik (IDE), Halmstad Embedded and Intelligent Systems Research (EIS), Inbyggda system (CERES).
    Uhlemann, Elisabeth
    Högskolan i Halmstad, Sektionen för Informationsvetenskap, Data– och Elektroteknik (IDE), Halmstad Embedded and Intelligent Systems Research (EIS), Inbyggda system (CERES).
    Report on the Collaboration between CVIS and CERES in the Project Vehicle Alert System (VAS)2009Rapport (Annet vitenskapelig)
    Abstract [en]

    In March 2007, an agreement was made for interchange of experiences between CVIS and the Centre for Research on Embedded Systems (CERES) at Halmstad University in Sweden. The majority of the work relating to this collaboration has been conducted within the CERES project Vehicle Alert System (VAS), aiming to use vehicle-to-vehicle (V2V) and vehicle-to-infrastructure (V2I) communications to provide different types of warning messages. The main focus of the VAS project is on communication and in particular the lower layers of the communication stack are investigated. VAS involves academic researchers from Halmstad University as well as researchers from Volvo Technology, SP Technical Research Institute of Sweden and the company Free2move. This report presents the results of the VAS project, its publications, and other issues of interest both to the CVIS consortium as well as a broader scope.

  • 221.
    Bilstrup, Katrin
    et al.
    Högskolan i Halmstad, Sektionen för Informationsvetenskap, Data– och Elektroteknik (IDE), Halmstad Embedded and Intelligent Systems Research (EIS), Inbyggda system (CERES).
    Uhlemann, Elisabeth
    Högskolan i Halmstad, Sektionen för Informationsvetenskap, Data– och Elektroteknik (IDE), Halmstad Embedded and Intelligent Systems Research (EIS), Inbyggda system (CERES).
    Ström, Erik G.
    Chalmers.
    Medium access control in vehicular networks based on the upcoming IEEE 802.11p standard2008Inngår i: World Congress on Intelligent Transport Systems (ITS), 2008, World Congress on ITS , 2008, s. 12-Konferansepaper (Fagfellevurdert)
    Abstract [en]

    In this paper, initial simulations are presented showing that the upcoming IEEE 802.11p standard is not suitable for traffic safety applications requiring reliable, low delay communication between vehicles. The medium access control procedure is one of the most important parts in the design of delay-constrained communication systems, and emerging vehicle safety applications put new stringent demands on timely and reliable delivery of data packets. The medium access procedure used in 802.11p is carrier sense multiple access, which is inherently unsuitable for time-critical data traffic since it is contention-based and cannot provide a finite upper bound on the time to channel access. The simulation results indicate that with IEEE 802.11p, channel access cannot be granted in a manner that is sufficiently predictable to support reliable, low-delay communications between vehicles on a highway.

  • 222.
    Bilstrup, Katrin
    et al.
    Högskolan i Halmstad, Sektionen för Informationsvetenskap, Data– och Elektroteknik (IDE), Halmstad Embedded and Intelligent Systems Research (EIS), Inbyggda system (CERES).
    Uhlemann, Elisabeth
    Högskolan i Halmstad, Sektionen för Informationsvetenskap, Data– och Elektroteknik (IDE), Halmstad Embedded and Intelligent Systems Research (EIS), Inbyggda system (CERES).
    Ström, Erik G.
    Chalmers.
    Bilstrup, Urban
    Högskolan i Halmstad, Sektionen för Informationsvetenskap, Data– och Elektroteknik (IDE), Halmstad Embedded and Intelligent Systems Research (EIS), Inbyggda system (CERES).
    Evaluation of the IEEE 802.11p MAC method for vehicle-to-vehicle communication2008Inngår i: 68th IEEE Vehicular Technology Conference, 2008. VTC 2008-Fall: IEEE Vehicular Technology Conference (VTC) (2008), Piscataway, N.J.: IEEE Press, 2008, s. 1-5Konferansepaper (Fagfellevurdert)
    Abstract [en]

    In this paper the medium access control (MAC) method of the upcoming vehicular communication standard IEEE 802.11p has been simulated in a highway scenario with periodic broadcast of time-critical packets (so-called heartbeat messages) in a vehicle-to-vehicle situation. The 802.11p MAC method is based on carrier sense multiple access (CSMA) where nodes listen to the wireless channel before sending. If the channel is busy, the node must defer its access and during high utilization periods this could lead to unbounded delays. This well-known property of CSMA is undesirable for time critical communications. The simulation results reveal that a specific node/vehicle is forced to drop over 80% of its heartbeat messages because no channel access was possible before the next message was generated. To overcome this problem, we propose to use self-organizing time division multiple access (STDMA) for real-time data traffic between vehicles. This MAC method is already successfully applied in commercial surveillance applications for ships (AIS) and airplanes (VDL mode 4). Our initial results indicate that STDMA outperforms CSMA for time-critical traffic safety applications in ad hoc vehicular networks.

  • 223.
    Bilstrup, Katrin
    et al.
    Högskolan i Halmstad, Sektionen för Informationsvetenskap, Data– och Elektroteknik (IDE), Halmstad Embedded and Intelligent Systems Research (EIS), Inbyggda system (CERES).
    Uhlemann, Elisabeth
    Högskolan i Halmstad, Sektionen för Informationsvetenskap, Data– och Elektroteknik (IDE), Halmstad Embedded and Intelligent Systems Research (EIS), Inbyggda system (CERES).
    Ström, Erik G.
    Högskolan i Halmstad, Sektionen för Informationsvetenskap, Data– och Elektroteknik (IDE), Halmstad Embedded and Intelligent Systems Research (EIS), Inbyggda system (CERES).
    Bilstrup, Urban
    Högskolan i Halmstad, Sektionen för Informationsvetenskap, Data– och Elektroteknik (IDE), Halmstad Embedded and Intelligent Systems Research (EIS), Inbyggda system (CERES).
    On the ability of the 802.11p MAC method and STDMA to support real-time vehicle-to-vehicle communications2009Inngår i: EURASIP Journal on Wireless Communications and Networking, ISSN 1687-1472, E-ISSN 1687-1499, Vol. 2009, nr 902414, s. 1-14Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Traffic safety applications using vehicle-to-vehicle (V2V) communication is an emerging and promising area within the intelligent transportation systems (ITS) sphere. Many of these new applications require real-time communication with high reliability, meaning that packets must be successfully delivered before a certain deadline. Applications with early deadlines are expected to require direct V2V communications, and the only standard currently supporting this is the upcoming IEEE 802.11p, included in the wireless access in vehicular environment (WAVE) stack. To meet a real-time deadline, timely and predictable access to the channel is paramount. However, the medium access method used in 802.11p, carrier sense multiple access with collision avoidance (CSMA/CA), does not guarantee channel access before a finite deadline. In this paper, we analyze the communication requirements introduced by traffic safety applications, namely, low delay, reliable, real-time communications.We show by simulation of a simple, but realistic, highway scenario, that vehicles using CSMA/CA can experience unacceptable channel access delays and, therefore, 802.11p does not support real-time communications. In addition, we present a potential remedy for this problem, namely, the use of self-organizing time division multiple access (STDMA). The real-time properties of STDMA are investigated by means of the same highway simulation scenario, with promising results.

  • 224.
    Bilstrup, Katrin
    et al.
    Högskolan i Halmstad, Sektionen för Informationsvetenskap, Data– och Elektroteknik (IDE), Halmstad Embedded and Intelligent Systems Research (EIS), Inbyggda system (CERES).
    Uhlemann, Elisabeth
    Högskolan i Halmstad, Sektionen för Informationsvetenskap, Data– och Elektroteknik (IDE), Halmstad Embedded and Intelligent Systems Research (EIS), Inbyggda system (CERES).
    Ström, Erik G.
    Chalmers, Gothenburg.
    Bilstrup, Urban
    Högskolan i Halmstad, Sektionen för Informationsvetenskap, Data– och Elektroteknik (IDE), Halmstad Embedded and Intelligent Systems Research (EIS), Inbyggda system (CERES).
    On the ability of the IEEE 802.11p and STDMA to provide predictable channel access2009Inngår i: Proceedings of the 16th World Congress on Intelligent Transport Systems (ITS), 2009, s. 10-Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Emerging traffic safety applications requiring low delay communications will need vehicle ad-hoc networks. The only communication standard currently supporting this is IEEE 802.11p. However, 802.11p uses the medium access method CSMA/CA, which has a major drawback: unbounded worst case channel access delay. We therefore propose an algorithm already in commercial use in the shipping industry: STDMA. With STDMA, nodes always get predictable channel access regardless of the number of competing nodes and the maximum delay is deterministic. In this paper we elaborated with different parameter settings for the two protocols with the aim of improving performance without altering the standards.

     

  • 225.
    Bilstrup, Urban
    Högskolan i Halmstad, Sektionen för Informationsvetenskap, Data– och Elektroteknik (IDE), Halmstad Embedded and Intelligent Systems Research (EIS), Centrum för forskning om inbyggda system (CERES).
    Bluetooth and Wireless Multihop Networks in Industrial Communication Systems2008Doktoravhandling, monografi (Annet vitenskapelig)
    Abstract [en]

    The objective of this thesis is to investigate the use of short-range wireless communication technology in industrial communication systems where there is a need for guaranteed timely delivery of correct information. Methods for achieving such capability are developed in the context of the physical layer, the data link layer and the application layer. Based on the insight that it is impossible to achieve strict determinism in a wireless communication system, a probabilistic definition of hard real-time systems is suggested, and thus a guarantee is given in the form of the probability of fulfilling a certain goal. Since a wireless channel is time variant, it is also necessary to continuously keep track of available resources. Allocation and link management methods for wireless communication systems therefore need to be dynamic and of an online character. An exhaustive resource allocation method with redundancy is first proposed for single message delivery and then extended for the operation of a single Bluetooth piconet. However, many devices in an industrial automation system have limited computational resources, especially if wireless sensors/actuators powered by battery or wireless power are considered. This implies that methods used for resource allocation must be of low computational complexity. The complexity issue becomes evident when large systems are implemented, even if each individual sensor generates small amounts of data. The upstream and downstream flows of data grow rapidly in a hierarchical system with many sub-systems, sensors and actuators. It is empirically shown that the aggregated data flow in a monitoring system requires powerful communication nodes already at low levels in the industrial communication hierarchy. A predictable system requires that representative entities for the available resources are defined. In a communication system with a single broadcast domain, such as a single Bluetooth piconet, the resource space is often limited to the time domain. When a multihop wireless network with multiple broadcast domains is considered, the spatial domain is added as an available resource and, if a multi-channel radio transceiver is used, the frequency is also added as an available resource domain. These three domains represent the physical resource space that is available for a wireless multihop network. These are subject to trade-off in all of the three lowest protocol layers, and one of the most challenging problems in the design of a wireless multihop network is how to achieve efficient sharing of these resources. This problem is addressed by proposing a clustered architecture based on a dual-radio node that enables dynamic use of these resource domains.

  • 226.
    Bilstrup, Urban
    Högskolan i Halmstad, Akademin för informationsteknologi, Halmstad Embedded and Intelligent Systems Research (EIS).
    Design Space Exploration of Wireless Multihop Networks2005Licentiatavhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    This thesis explores the feasible design space of wireless multihop networks and identifies fundamental design parameters. In the process of exploring it is important to ignore all details and instead take a holistic view. This means that all protocol details are overseen, all details of radio wave propagation models are overseen and the system is modelled strictly on an architectural level. From a theoretical information perspective, there is a limit to the capacity that a certain bandwidth and a certain signal-to-noise ratio at the receiver can provide. This limit is approximated as a volume in the time-frequency-space domain. A single transmission is represented as an occupied volume in this domain. A wireless multihop network covers a spatial area, and the question is how multiple numbers of transmission volumes can be fit into a given limited spatial area. This volume fitting should be done in order to maximize the overall performance or to trade available resources to favour a specific characteristic in the wireless multihop network. The volume model is used for the design space exploration of a wireless multihop network. It is argued that the fault tolerance and the energy gain achieved in a multihop topology are its strength as compared to a single-hop architecture. It is further shown that the energy gain is achieved at the expense of delay and a greater end-to-end error probability. This indicates that these parameters must be very carefully balanced in order to gain in the global overall performance perspective. It can further be concluded that the overall spatial capacity is increased as a result of the spatial channel reuse in a multihop topology. On the other hand, it is also shown that the multihop topology introduces a rather stringent geometrical capacity limitation when the number of nodes of a wireless multihop network is increased. The dynamics (e.g. node mobility, changing radio channels etc.) of a large scale wireless multihop network is also a limiting factor. The nodes’ mobility creates a knowledge horizon beyond which very little can be known about the present network topology.

  • 227.
    Bilstrup, Urban
    et al.
    Högskolan i Halmstad, Sektionen för Informationsvetenskap, Data– och Elektroteknik (IDE), Halmstad Embedded and Intelligent Systems Research (EIS), Centrum för forskning om inbyggda system (CERES).
    Bilstrup, Katrin
    Högskolan i Halmstad, Sektionen för Informationsvetenskap, Data– och Elektroteknik (IDE), Halmstad Embedded and Intelligent Systems Research (EIS), Centrum för forskning om inbyggda system (CERES).
    Svensson, Bertil
    Högskolan i Halmstad, Sektionen för Informationsvetenskap, Data– och Elektroteknik (IDE), Halmstad Embedded and Intelligent Systems Research (EIS), Centrum för forskning om inbyggda system (CERES).
    Wiberg, Per-Arne
    Högskolan i Halmstad, Sektionen för Informationsvetenskap, Data– och Elektroteknik (IDE), Halmstad Embedded and Intelligent Systems Research (EIS), Centrum för forskning om inbyggda system (CERES).
    The use of clustered wireless multihop networks in industrial settings2007Inngår i: ETFA 2007: IEEE Conference on Emerging Technologies and Factory Automation, Vols 1-3, Piscataway, NJ: IEEE Press, 2007, s. 211-218Konferansepaper (Fagfellevurdert)
    Abstract [en]

    This paper suggests a cluster collision avoidance mechanism and a dual transceiver architecture to be used in a clustered wireless multihop network. These two contributions make the clustered wireless multihop network the preferred architecture for future industrial wireless networks. The wireless multihop cluster consists of one master and several slaves, where some of the slaves will act as gateways between different clusters. Frequency hopping spread spectrum is used on a cluster level and to avoid frequency collisions between clusters a "neighbor cluster collision avoidance mechanism" is proposed and evaluated through simulations. To break up the dependence between the clusters, introduced by the gateway nodes, each node is equipped with two transceivers. The paper is concluded with a suggestion to use a clustered wireless multihop network with orthogonal hopping sequences for an industrial setting.

  • 228.
    Bilstrup, Urban
    et al.
    Högskolan i Halmstad, Sektionen för Informationsvetenskap, Data– och Elektroteknik (IDE), Halmstad Embedded and Intelligent Systems Research (EIS), Centrum för forskning om inbyggda system (CERES).
    Bilstrup, Katrin
    Högskolan i Halmstad, Sektionen för Informationsvetenskap, Data– och Elektroteknik (IDE), Halmstad Embedded and Intelligent Systems Research (EIS), Centrum för forskning om inbyggda system (CERES).
    Svensson, Bertil
    Högskolan i Halmstad, Sektionen för Informationsvetenskap, Data– och Elektroteknik (IDE), Halmstad Embedded and Intelligent Systems Research (EIS), Centrum för forskning om inbyggda system (CERES).
    Wiberg, Per-Arne
    Högskolan i Halmstad, Sektionen för Informationsvetenskap, Data– och Elektroteknik (IDE), Halmstad Embedded and Intelligent Systems Research (EIS), Centrum för forskning om inbyggda system (CERES).
    Using Dual-Radio Nodes to Enable Quality of Service in a Clustered Wireless Mesh Network2006Inngår i: IEEE Conference on Emerging Technologies and Factory Automation, 2006. ETFA '06, Piscataway, N.J.: IEEE Press, 2006, s. 54-61Konferansepaper (Fagfellevurdert)
    Abstract [en]

    In this paper some well established wireless technologies are merged into a new concept solution for a future industrial wireless mesh network. The suggested clustered wireless mesh network can handle probabilistic quality of service guarantees and is based on a dual-radio node architecture using synchronized frequency hopping spread spectrum Bluetooth radios. The proposed architecture gives a heuristic solution to the inter-cluster scheduling problem of gateway nodes in clustered architectures and breaks up the dependence between the local medium access schedules of adjacent clusters. The dual-radio feature also enables higher network connectivity, implying, for example, that a higher link redundancy can be achieved.

  • 229.
    Bilstrup, Urban
    et al.
    Högskolan i Halmstad, Sektionen för Informationsvetenskap, Data– och Elektroteknik (IDE), Halmstad Embedded and Intelligent Systems Research (EIS), Inbyggda system (CERES).
    Jonsson, Magnus
    Högskolan i Halmstad, Sektionen för Informationsvetenskap, Data– och Elektroteknik (IDE), Halmstad Embedded and Intelligent Systems Research (EIS), Inbyggda system (CERES).
    Svensson, Bertil
    Högskolan i Halmstad, Sektionen för Informationsvetenskap, Data– och Elektroteknik (IDE), Halmstad Embedded and Intelligent Systems Research (EIS), Inbyggda system (CERES).
    The next challenge for the communication society: co-operating embedded systems2003Konferansepaper (Fagfellevurdert)
  • 230.
    Bilstrup, Urban
    et al.
    Högskolan i Halmstad, Akademin för informationsteknologi, Halmstad Embedded and Intelligent Systems Research (EIS), Centrum för forskning om inbyggda system (CERES).
    Parsapoor, Mahboobeh
    Högskolan i Halmstad, Akademin för informationsteknologi, Halmstad Embedded and Intelligent Systems Research (EIS), Centrum för forskning om inbyggda system (CERES).
    A Framework and Architecture for a Cognitive Manager Based on a Computational Model of Human Emotional Learning2013Inngår i: Proceedings of SDR-WInnComm-Europe 2013: Wireless Innovation European Conference on Wireless Communications Technologies and Software Defined Radio / [ed] Lee Pucker, Kuan Collins & Stephanie Hamill, 2013, s. 64-72Konferansepaper (Fagfellevurdert)
    Abstract [en]

    In this paper we propose an architecture for a cognitive engine that is based on the emotional learning cycle instead of the traditional cognitive cycle. The cognitive cycle that traditionally has been used as reference for cognitive radio is on the basis of the Unified Theories of Cognition (UTC) to model rational decision making in humans. UTC represents a rational goal-oriented decision-action made by an intelligent agent. However, the emotional cycle represents an emotional reaction-oriented cycle instead. These two models differ in function and structure of learning, decision making and optimization. In this work the structure of these two learning cycles are compared and a computational model for artificial emotional learning based engine is suggested.

  • 231.
    Bilstrup, Urban
    et al.
    Högskolan i Halmstad, Akademin för informationsteknologi, Halmstad Embedded and Intelligent Systems Research (EIS).
    Stranne, Frida
    Högskolan i Halmstad, Akademin för lärande, humaniora och samhälle, Centrum för lärande, kultur och samhälle (CLKS). The Swedish Institute for North American Studies (SINAS), Uppsala University, Uppsala, Sweden.
    Peace in Cyberspace Will Not Take Place2016Konferansepaper (Fagfellevurdert)
    Abstract [en]

    The ongoing debate whether cyberwar exists or not is odd and to large extent based on an Industrial age view of the definition of war. The ongoing digital revolution ends the industrial age and it was in the context of the industrial age that the Clausewitzian theories of war were defined. The industrial age was built upon machines and physical objects, and the theories of war in this era were also based on these elements. However, when the importance of physical values is vanishing and replaced by other values, as information and knowledge, the fundamental elements of war in the industrial age becomes week. An extension of the theories of war in the information age is that destruction of digital assets is representing the same element of violence, if it potentially cripples an enemy to defeat. When a society’s valuable assets are in the digital form and not necessarily even present within the geographical area of a sovereign state one maybe have to reconsider the understanding of war. This paper explores the discourse framing war in the information age, and conducts a discussion on how to define peace and war in cyberspace, especially in the context of digital violence.

  • 232.
    Bilstrup, Urban
    et al.
    Högskolan i Halmstad, Sektionen för Informationsvetenskap, Data– och Elektroteknik (IDE), Halmstad Embedded and Intelligent Systems Research (EIS), Centrum för forskning om inbyggda system (CERES).
    Wiberg, Per-Arne
    Free2move AB.
    An architecture comparison between a wireless sensor network and an active RFID system2004Inngår i: The 29th Annual IEEE International Conference on Local Computer Networks, 2004, IEEE , 2004, s. 583-584Konferansepaper (Fagfellevurdert)
    Abstract [en]

    In This work a new hardware platform for active RFID and wireless sensor network is presented. Furthermore a comparison of these two architectures is performed, i.e., the singlehop and the multihop architecture. The comparison reveals important issues regarding the utilization and energy consumption for the singlehop as well as for the multihop architecture.

  • 233.
    Bilstrup, Urban
    et al.
    Högskolan i Halmstad, Sektionen för Informationsvetenskap, Data– och Elektroteknik (IDE), Halmstad Embedded and Intelligent Systems Research (EIS), Centrum för forskning om inbyggda system (CERES).
    Wiberg, Per-Arne
    Högskolan i Halmstad, Sektionen för Informationsvetenskap, Data– och Elektroteknik (IDE), Halmstad Embedded and Intelligent Systems Research (EIS), Centrum för forskning om inbyggda system (CERES).
    An Implementation of a 3-tier Hierarchical Wireless Sensor Network2006Inngår i: 2006 IEEE International Conference on Industrial Informatics, Piscataway, N.J.: IEEE Press, 2006, s. 138-143Konferansepaper (Fagfellevurdert)
    Abstract [en]

    In this paper an implementation of a wireless sensor network is described. The aim with the implementation is to investigate if present design patterns are applicable on wireless sensor networks. A 3-tier model is adopted as a possible candidate for the software as well as for the network architecture. The implemented wireless sensor network consists of a heterogeneous set of hardware devices such as sensors, sensor hubs, beepers, PDAs and connectors. Most of the hardware components are COTS and most of the software is GNU licensed. All these form a 3-tier hierarchical network architecture.

  • 234.
    Bilstrup, Urban
    et al.
    Högskolan i Halmstad, Akademin för informationsteknologi, Halmstad Embedded and Intelligent Systems Research (EIS).
    Wiberg, Per-Arne
    Högskolan i Halmstad, Akademin för informationsteknologi, Halmstad Embedded and Intelligent Systems Research (EIS).
    Bluetooth in industrial environment2000Inngår i: 2000 IEEE International Workshop on Factory Communication Systems: proceedings : 6-8 September, 2000, ISEP, Porto, Portugal / [ed] IEEE, Piscataway, N.J.: IEEE Press, 2000, s. 239-246Konferansepaper (Fagfellevurdert)
    Abstract [en]

    In this paper an initial study of the use of Bluetooth in industrial environment is presented. The tests have been performed at a paper-mill, and in an office environment at Halmstad University. It shows the possibility to use Bluetooth for wireless short range communication in an industrial environment.

  • 235.
    Bilstrup, Urban
    et al.
    Högskolan i Halmstad, Sektionen för Informationsvetenskap, Data– och Elektroteknik (IDE), Halmstad Embedded and Intelligent Systems Research (EIS).
    Wiberg, Per-Arne
    Högskolan i Halmstad, Sektionen för Informationsvetenskap, Data– och Elektroteknik (IDE), Halmstad Embedded and Intelligent Systems Research (EIS).
    Routing protocol for wireless real-time multihop networks1999Konferansepaper (Fagfellevurdert)
  • 236.
    Binotto, Alécio P. D.
    et al.
    Fraunhofer IGD / Technische, Universität Darmstadt, Germany.
    Freitas, Edison Pignaton
    Högskolan i Halmstad, Akademin för informationsteknologi, Halmstad Embedded and Intelligent Systems Research (EIS).
    Götz, Marcelo
    Electrical Engineering Department, Federal University of Rio Grande do Sul, Brazil.
    Pereira, Carlos E.
    Informatics Institute, Federal University of Rio Grande do Sul, Brazil.
    Stork, André
    Fraunhofer IGD / Technische, Universität Darmstadt, Germany.
    Larsson, Tony
    Högskolan i Halmstad, Akademin för informationsteknologi, Halmstad Embedded and Intelligent Systems Research (EIS).
    Dynamic Self-Rescheduling of Tasks over a Heterogeneous Platform2008Inngår i: Proceedings of the 2008 International Conference on Reconfigurable Computing and FPGAs, Los Alamitos, Calif.: IEEE Computer Society, 2008, s. 253-258Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Modern applications require powerful high-performance platforms to deal with many different algorithms that make use of massive calculations. At the same time, low-cost and high-performance specific hardware (e.g., GPU, PPU) are rising and the CPUs turned to multiple cores, characterizing together an interesting and powerful heterogeneous execution platform. Therefore, self-adaptive computing is a potential paradigm for those scenarios as it can provide flexibility to explore the computational resources on heterogeneous cluster attached to a high-performance computer system platform. As the first step towards a run-time reschedule load-balancing framework targeting that kind of platform, application time requirements and its crosscutting behavior play an important role for task allocation decisions. This paper presents a strategy for self-reallocation of specific tasks, including dynamic created ones, using aspect-oriented paradigms to address non-functional application timing constraints in the design phase. Additionally, as a case study, a special attention on Radar Image Processing will be given in the context of a surveillance system based on Unmanned Aerial Vehicles (UAV).

  • 237.
    Binotto, Alécio Pedro Delazari
    et al.
    Informatics Institute, Federal University of Rio Grande do Sul, Porto Alegre, Brazil.
    Pignaton de Freitas, Edison
    Högskolan i Halmstad, Akademin för informationsteknologi, Halmstad Embedded and Intelligent Systems Research (EIS), Centrum för forskning om inbyggda system (CERES). Informatics Institute, Federal University of Rio Grande do Sul, Porto Alegre, Brazil.
    Pereira, Carlos Eduardo
    Electrical Engineering Department, Federal University of Rio Grande do Sul, Porto Alegre, Brazil.
    Larsson, Tony
    Högskolan i Halmstad, Akademin för informationsteknologi, Halmstad Embedded and Intelligent Systems Research (EIS), Centrum för forskning om inbyggda system (CERES).
    Towards Dynamic Task Scheduling and Reconfiguration using an Aspect Oriented Approach applied on Real-time concerns of Industrial Systems2009Inngår i: Elsevier IFAC Publications / IFAC Proceedings series, ISSN 1474-6670, Vol. 13, nr PART 1, s. 1423-1428Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    High performance computational platforms are required by industries that make use of automatic methods to manage modern machines, which are mostly controlled by high-performance specific hardware with processing capabilities. It usually works together with CPUs, forming a powerful execution platform. On an industrial production line, distinct tasks can be assigned to be processed by different machines depending on certain conditions and production parameters. However, these conditions can change at run-time influenced mainly by machine failure and maintenance, priorities changes, and possible new better task distribution. Therefore, self-adaptive computing is a potential paradigm as it can provide flexibility to explore the machine resources and improve performance on different execution scenarios of the production line. One approach is to explore scheduling and run-time task migration among machines’ hardware towards a balancing of tasks, aiming performance and production gain. This way, the monitoring of time requirements and its crosscutting behaviour play an important role for task (re)allocation decisions. This paper introduces the use of software aspect-oriented paradigms to perform machines’ monitoring and a self-rescheduling strategy of tasks to address nonfunctional timing constraints. As case study, tasks for a production line of aluminium ingots are designed. © 2009 IFAC.

  • 238.
    Binotto, A.P.D.
    et al.
    Fraunhofer IGD / TU Darmstadt, Germany.
    Pignaton de Freitas, Edison
    Högskolan i Halmstad, Sektionen för Informationsvetenskap, Data– och Elektroteknik (IDE), Halmstad Embedded and Intelligent Systems Research (EIS).
    Pereira, Carlos Eduardo
    PPGC UFRGS, Brazil.
    Stork, André
    Fraunhofer IGD / TU Darmstadt, Germany.
    Larsson, Tony
    Högskolan i Halmstad, Sektionen för Informationsvetenskap, Data– och Elektroteknik (IDE), Halmstad Embedded and Intelligent Systems Research (EIS).
    Real-time task reconfiguration support applied to an UAV-based surveillance system2008Inngår i: 2008 International Multiconference on Computer Science and Information Technology (Imcsit) / [ed] Ganzha, M, Piscataway, N.J.: IEEE Press, 2008, s. 581-588Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Modern surveillance systems, such as those based on the use of Unmanned Aerial Vehicles, require powerful high- performance platforms to deal with many different algorithms that make use of massive calculations. At the same time, low- cost and high-performance specific hardware (e.g., GPU, PPU) are rising and the CPUs turned to multiple cores, characteriz- ing together an interesting and powerful heterogeneous execu- tion platform. Therefore, reconfigurable computing is a poten- tial paradigm for those scenarios as it can provide flexibility to explore the computational resources on heterogeneous cluster attached to a high-performance computer system platform. As the first step towards a run-time reconfigurable workload bal- ancing framework targeting that kind of platform, application time requirements and its crosscutting behavior play an impor- tant role for task allocation decisions. This paper presents a strategy to reallocate specific tasks in a surveillance system composed by a fleet of Unmanned Aerial Vehicles using aspect- oriented paradigms in order to address non-functional applica- tion timing constraints in the design phase. An aspect support from a framework called DERAF is used to support reconfigu- ration requirements and provide the resource information needed by the reconfigurable load-balancing strategy. Finally, for the case study, a special attention on Radar Image Process- ing will be given.

  • 239.
    Blom, Mathias Carl
    et al.
    Department of Clinical Sciences, Lund University, Lund, Sweden.
    Ashfaq, Awais
    Högskolan i Halmstad, Akademin för informationsteknologi, Halmstad Embedded and Intelligent Systems Research (EIS), CAISR Centrum för tillämpade intelligenta system (IS-lab). Halland Hospital, Region Halland, Halmstad, Sweden.
    Pinheiro Sant'Anna, Anita
    Högskolan i Halmstad, Akademin för informationsteknologi, Halmstad Embedded and Intelligent Systems Research (EIS), CAISR Centrum för tillämpade intelligenta system (IS-lab).
    Anderson, Philip D.
    Department of Emergency Medicine, Brigham and Women’s Hospital, Boston, Massachusetts, USA & Harvard Medical School, Boston, Massachusetts, USA.
    Lingman, Markus
    Halland Hospital, Region Halland, Sweden & Department of Molecular and Clinical Medicine/Cardiology, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden.
    Training machine learning models to predict 30-day mortality in patients discharged from the emergency department: a retrospective, population based registry study2019Inngår i: BMJ Open, ISSN 2044-6055, E-ISSN 2044-6055, Vol. 9, nr 8, artikkel-id e028015Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Background: Aggressive treatment at end-of-life (EOL) can be traumatic to patients and may not add clinical benefit. Absent an accurate prognosis of death, individual level biases may prevent timely discussions about the scope of EOL care and patients are at risk of being subject to care against their desire. The aim of this work is to develop predictive algorithms for identifying patients at EOL, with clinically meaningful discriminatory power.

    Methods: Retrospective, population-based study of patients utilizing emergency departments (EDs) in Sweden, Europe. Electronic health records (EHRs) were used to train supervised learning algorithms to predict all-cause mortality within 30 days following ED discharge. Algorithm performance was validated out of sample on EHRs from a separate hospital, to which the algorithms were previously unexposed.

    Results: Of 65,776 visits in the development set, 136 (0.21%) experienced the outcome. The algorithm with highest discrimination attained ROC-AUC 0.945 (95% CI 0.933 - 0.956), with sensitivity 0.869 (95% CI 0.802, 0.931) and specificity 0.858 (0.855, 0.860) on the validation set.

    Conclusions: Multiple algorithms displayed excellent discrimination and outperformed available indexes for short-term mortality prediction. The practical utility of the algorithms increases as the required data were captured electronically and did not require de novo data collection.

    Trial registration number: Not applicable.

  • 240.
    Blomqvist, Daniel
    et al.
    Högskolan i Halmstad, Sektionen för Informationsvetenskap, Data– och Elektroteknik (IDE).
    Byttner, Stefan
    Högskolan i Halmstad, Akademin för informationsteknologi, Halmstad Embedded and Intelligent Systems Research (EIS), Intelligenta system (IS-lab).
    Rögnvaldsson, Thorsteinn
    Högskolan i Halmstad, Akademin för informationsteknologi, Halmstad Embedded and Intelligent Systems Research (EIS), Intelligenta system (IS-lab).
    Holmberg, Ulf
    Högskolan i Halmstad, Akademin för informationsteknologi, Halmstad Embedded and Intelligent Systems Research (EIS), Intelligenta system (IS-lab).
    Different Strategies for Transient Control of the Air-Fuel Ratio in a SI Engine2000Inngår i: SAE transactions : journal of fuels and lubricants, Warrendale, Pa.: Society of automotive engineers (SAE) , 2000, Vol. 109Konferansepaper (Fagfellevurdert)
    Abstract [en]

    This paper compares several strategies for air-fuel ratio tran-sient control. The strategies are: A factory-standard look-up table based system (a SAAB Trionic 5), a feedback PI controller with and without feed-forward throttle correction, a linear feed-forward control algorithm, and two nonlinear feed- forward algorithms based on artificial neural networks. The control strategies have been implemented and evaluated in a SAAB 9000 car during a transient driving test, consisting of an acceleration in the second gear from an engine speed of 1500 rpm to 3000 rpm. The best strategies are found to be the neural network based ones, followed by the table based factory system. The two feedback PI controllers offer the poorest performance.

  • 241.
    Bocharova, Irina
    et al.
    St.-Petersburg University of Information Technologies, Mechanics and Optics, St.-Petersburg, Russia & University of Tartu, Tartu, Estonia.
    Kudryashov, Boris
    St.-Petersburg University of Information Technologies, Mechanics and Optics, St.-Petersburg, Russia & University of Tartu, Tartu, Estonia.
    Lyamin, Nikita
    Högskolan i Halmstad, Akademin för informationsteknologi, Halmstad Embedded and Intelligent Systems Research (EIS), Centrum för forskning om inbyggda system (CERES).
    Frick, Erik
    AstaZero Hällered, Sandhult, Sweden.
    Rabi, Maben
    Högskolan i Halmstad, Akademin för informationsteknologi, Halmstad Embedded and Intelligent Systems Research (EIS), Centrum för forskning om inbyggda system (CERES).
    Vinel, Alexey
    Högskolan i Halmstad, Akademin för informationsteknologi, Halmstad Embedded and Intelligent Systems Research (EIS), Centrum för forskning om inbyggda system (CERES). Department of Electrical Engineering, Western Norway University of Applied Sciences, Bergen, Norway.
    Low Delay Inter-Packet Coding in Vehicular Networks2019Inngår i: Future Internet, ISSN 1999-5903, E-ISSN 1999-5903, Vol. 11, nr 12, artikkel-id 212Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In Cooperative Intelligent Transportation Systems (C-ITSs), vehicles need to wirelessly connect with Roadside units (RSUs) over limited durations when such point-to-point connections are possible. One example of such communications is the downloading of maps to the C-ITS vehicles. Another example occurs in the testing of C-ITS vehicles, where the tested vehicles upload trajectory records to the roadside units. Because of real-time requirements, and limited bandwidths, data are sent as User Datagram Protocol (UDP) packets. We propose an inter-packet error control coding scheme that improves the recovery of data when some of these packets are lost; we argue that the coding scheme has to be one of convolutional coding. We measure performance through the session averaged probability of successfully delivering groups of packets. We analyze two classes of convolution codes and propose a low-complexity decoding procedure suitable for network applications. We conclude that Reed–Solomon convolutional codes perform better than Wyner–Ash codes at the cost of higher complexity. We show this by simulation on the memoryless binary erasure channel (BEC) and channels with memory, and through simulations of the IEEE 802.11p DSRC/ITS-G5 network at the C-ITS test track AstaZero.

  • 242.
    Bocharova, Irina
    et al.
    Department of Information Systems, St. Petersburg University of Information Technologies, Mechanics and Optics, St.-Petersburg, Russia & Institute of Computer Science, University of Tartu, Estonia.
    Kudryashov, Boris
    Department of Information Systems, St. Petersburg University of Information Technologies, Mechanics and Optics, St.-Petersburg, Russia & Institute of Computer Science, University of Tartu, Estonia.
    Rabi, Maben
    Högskolan i Halmstad, Akademin för informationsteknologi, Halmstad Embedded and Intelligent Systems Research (EIS).
    Lyamin, Nikita
    Högskolan i Halmstad, Akademin för informationsteknologi, Halmstad Embedded and Intelligent Systems Research (EIS), Centrum för forskning om inbyggda system (CERES).
    Dankers, Wouter
    Volvo GTT, Goteborg, Sweden.
    Frick, Erik
    AstaZero, Hällered, Sandhult, Sweden.
    Vinel, Alexey
    Högskolan i Halmstad, Akademin för informationsteknologi, Halmstad Embedded and Intelligent Systems Research (EIS), Centrum för forskning om inbyggda system (CERES). Department of Electrical Engineering, Western Norway University of Applied Sciences, Bergen, Norway.
    Characterizing Packet Losses in Vehicular Networks2019Inngår i: IEEE Transactions on Vehicular Technology, ISSN 0018-9545, E-ISSN 1939-9359, Vol. 68, nr 9, s. 8347-8358Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    To enable testing and performance evaluation of new connected and autonomous driving functions, it is important to characterize packet losses caused by degradation in vehicular (V2X) communication channels. In this paper we suggest an approach to constructing packet loss models based on the socalled Pseudo-Markov chains (PMC). The PMC based model needs only short training sequences, has low computational complexity, and yet provides more precise approximations than known techniques. We show how to learn PMC models from either empirical records of packet receptions, or from analytical models of fluctuations in the received signal strength. In particular, we validate our approach by applying it on (i) V2X packet reception data collected from an active safety test run, which used the LTE network of the AstaZero automotive testing site in Sweden, and (ii) variants of the Rician fading channel models corresponding to two models of correlations of packet losses. We also show that initializing the Baum-Welch algorithm with a second order PMC model leads to a high accuracy model. © 2019 IEEE.

  • 243.
    Bocharova, Irina
    et al.
    ITMO University, Saint Petersburg, Russia & University of Tartu, Tartu, Estonia.
    Kudryashov, Boris
    ITMO University, Saint Petersburg, Russia & University of Tartu, Tartu, Estonia.
    Rabi, Maben
    Högskolan i Halmstad, Akademin för informationsteknologi, Halmstad Embedded and Intelligent Systems Research (EIS), Centrum för forskning om inbyggda system (CERES).
    Lyamin, Nikita
    Högskolan i Halmstad, Akademin för informationsteknologi, Halmstad Embedded and Intelligent Systems Research (EIS), Centrum för forskning om inbyggda system (CERES).
    Dankers, Wouter
    Volvo GTT, Göteborg, Sweden.
    Frick, Erik
    AstaZero, Hällered, Sweden.
    Vinel, Alexey
    Högskolan i Halmstad, Akademin för informationsteknologi, Halmstad Embedded and Intelligent Systems Research (EIS), Centrum för forskning om inbyggda system (CERES).
    Modeling Packet Losses in Communication Networks2019Inngår i: 2019 IEEE International Symposium on Information Theory: Proceedings, 2019, s. 1012-1016Konferansepaper (Fagfellevurdert)
    Abstract [en]

    An approach to constructing discrete models of packet losses suitable for a wide variety of communication network applications is studied. It is based on estimating parameters of probabilistic automata described via so-called pseudo-Markov chains. The new technique is applied both to approximating a discrete time analog process at the output of known channel models and to the experimental data stream. Comparison of models is performed by computing probabilities of more than m losses out of n transmitted packets (P (m, n)). It is shown that for the Rician fading channel with exponential correlation and correlation determined by a Bessel filter, the obtained rank-two and rank-three discrete modes, respectively, provide high accuracy coincidence of P (m, n) performances. The rank-three discrete model computed on the experimental data stream obtained from the LTE network provides significantly better approximation of P (≥ m, n) performance than that obtained by the Baum-Welch algorithm.

  • 244.
    Boeira, Felipe
    et al.
    Högskolan i Halmstad, Akademin för informationsteknologi, Halmstad Embedded and Intelligent Systems Research (EIS). Federal University of Rio Grande do Sul, Porto Alegre, Brazil & Linköping University, Linköping, Sweden.
    Barcellos, Marinho P.
    Federal University of Rio Grande do Sul, Porto Alegre, Brazil.
    Pignaton de Freitas, Edison
    Federal University of Rio Grande do Sul, Porto Alegre, Brazil.
    Vinel, Alexey
    Högskolan i Halmstad, Akademin för informationsteknologi, Halmstad Embedded and Intelligent Systems Research (EIS), Centrum för forskning om inbyggda system (CERES).
    Asplund, Mikael
    Linköping University, Linköping, Sweden.
    Effects of Colluding Sybil Nodes in Message Falsification Attacks for Vehicular Platooning2017Inngår i: 2017 IEEE Vehicular Networking Conference (VNC) / [ed] Onur Altintas, Claudio Casetti, Nicholas Kirsch, Renato Lo Cigno & Rui Meireles, 2017Konferansepaper (Fagfellevurdert)
    Abstract [en]

    This paper studies the impact of vulnerabilities associated with the Sybil attack (through falsification of multiple identities) and message falsification in vehicular platooning. Platooning employs Inter-Vehicular Communication (IVC) to control a group of vehicles. It uses broadcast information such as acceleration, position, and velocity to operate a longitudinal control law. Cooperation among vehicles allows platoons to reduce fuel consumption and risks associated with driver mistakes. In spite of these benefits, the use of network communication to control vehicles exposes a relevant attack surface that can be exploited by malicious actors. To carry out this study, we evaluate five scenarios to quantify the potential impact of such attacks, identifying how platoons behave under varying Sybil attack conditions and what are the associated safety risks. This research also presents the use of location hijacking attack. In this attack, innocent vehicles that are not part of a platoon are used as a way to create trust bond between the false identities and the physical vehicles. We demonstrate that the ability to create false identities increases the effectiveness of message falsification attacks by making them easier to deploy and harder to detect in time.

  • 245.
    Boeira, Felipe
    et al.
    Federal University of Rio Grande do Sul, Porto Alegre, Brazil.
    Barcellos, Marinho
    Federal University of Rio Grande do Sul, Porto Alegre, Brazil.
    Pignaton de Freitas, Edison
    Federal University of Rio Grande do Sul, Porto Alegre, Brazil.
    Vinel, Alexey
    Högskolan i Halmstad, Akademin för informationsteknologi, Halmstad Embedded and Intelligent Systems Research (EIS), Centrum för forskning om inbyggda system (CERES).
    Asplund, Mikael
    Linköping University, Linköping, Sweden.
    On the impact of sybil attacks in cooperative driving scenarios2017Inngår i: 2017 IFIP Networking Conference (IFIP Networking) and Workshops, IEEE, 2017Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Platooning employs a set of technologies to manage how a group of vehicles operates, including radar, GPS and Inter-Vehicular Communication (IVC). It uses broadcasted information such as acceleration, position and velocity to operate vehicle members of the platoon. Cooperation among vehicles allows platoons to reduce fuel consumption and risks associated with driver mistakes. In spite of these benefits, the use of IVC to control vehicles exposes a relevant attack surface that can be exploited by malicious actors. In this paper we study the impact of vulnerabilities associated with the Sybil attack (through falsification of multiple identities) and message falsification in vehicular platooning. Simulation results show that this attack may impact the longitudinal control and compromise the entire platoon control. © Copyright 2018 IEEE

  • 246.
    Bordag, Ljudmila A.
    Högskolan i Halmstad, Akademin för informationsteknologi, Halmstad Embedded and Intelligent Systems Research (EIS), Tillämpad matematik och fysik (MPE-lab).
    On Option-Valuation in Illiquid Markets: Invariant Solutions to a Nonlinear Model2008Inngår i: Mathematical control theory and finance / [ed] Andrey Sarychev; et al, Berlin: Springer Berlin/Heidelberg, 2008, s. 71-94Konferansepaper (Annet vitenskapelig)
    Abstract [en]

    The present model describes a perfect hedging strategy for a large trader. In this case the hedging strategy affects the price of the underlying security. The feedback-effect leads to a nonlinear version of the Black-Scholes partial differential equation. Using Lie group theory we reduce in special cases the partial differential equation to some ordinary differential equations. The Lie group found for the model equation gives rise to invariant solutions. Families of exact invariant solutions for special values of parameters are described. © 2008 Springer-Verlag Berlin Heidelberg.

  • 247.
    Bordag, Ljudmila A.
    Högskolan i Halmstad, Sektionen för Informationsvetenskap, Data– och Elektroteknik (IDE), Halmstad Embedded and Intelligent Systems Research (EIS), Tillämpad matematik och fysik (MPE-lab).
    Pricing options in illiquid markets: optimal systems, symmetry reductions and exact solutions2010Inngår i: Lobachevskii Journal of Mathematics, ISSN 1995-0802, E-ISSN 1818-9962, Vol. 31, nr 2, s. 90-99Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We study a class of nonlinear pricing models which involves the feedback effect from the dynamic hedging strategies on the price of asset introduced by  Sircar and Papanicolaou. We are first to study the case of a nonlinear demand function involved in the model. Using a Lie group analysis we investigate the symmetry properties of these nonlinear diffusion equations. We provide the optimal systems of subalgebras and the complete set of non-equivalent reductions of studied PDEs to ODEs. In most cases we obtain families of exact solutions or derive particular solutions to the equations.

  • 248.
    Bordag, Ljudmila A.
    Högskolan i Halmstad, Akademin för informationsteknologi, Halmstad Embedded and Intelligent Systems Research (EIS), Tillämpad matematik och fysik (MPE-lab).
    Study of the risk-adjusted pricing methodology model with methods of geometrical analysis2011Inngår i: Stochastics: An International Journal of Probablitiy and Stochastic Processes, ISSN 1744-2508, E-ISSN 1744-2516, Vol. 83, nr 4-6, s. 333-345Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Families of exact solutions are found to a nonlinear modification of the Black-Scholes equation. This risk-adjusted pricing methodology model (RAPM) incorporates both transaction costs and the risk from a volatile portfolio. Using the Lie group analysis we obtain the Lie algebra admitted by the RAPM equation. It gives us the possibility to describe an optimal system of subalgebras and the corresponding set of invariant solutions to the model. In this way we can describe the complete set of possible reductions of the nonlinear RAPM model. Reductions are given in the form of different second order ordinary differential equations. In all cases we provide exact solutions to these equations in an explicit or parametric form. Each of these solutions contains a reasonable set of parameters which allows one to approximate a wide class of boundary conditions. We discuss the properties of these reductions and the corresponding invariant solutions.

  • 249.
    Bordag, Ljudmila A.
    Högskolan i Halmstad, Sektionen för Informationsvetenskap, Data– och Elektroteknik (IDE), Halmstad Embedded and Intelligent Systems Research (EIS), Tillämpad matematik och fysik (MPE-lab).
    Symmetry reductions and exact solutions for nonlinear diffusion equations2009Inngår i: International Journal of Modern Physics A, ISSN 0217-751X, E-ISSN 1793-656X, Vol. 24, nr 8/9, s. 1713-1716Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The symmetry properties of nonlinear diffusion equations are studied using a Lie group analysis. Reductions and families of exact solutions are found for some of these equations.

    © 2009 World Scientific Publishing Company.

  • 250.
    Bordag, Ljudmila A.
    et al.
    Högskolan i Halmstad, Sektionen för Informationsvetenskap, Data– och Elektroteknik (IDE), Halmstad Embedded and Intelligent Systems Research (EIS), Tillämpad matematik och fysik (CAMP).
    Chkhetiani, O. G.
    Space Research Institute, Russian Academy of Sciences.
    Frohner, M.
    Brandenburgische Technische Universität Cottbus.
    Myrnyy, V.
    Brandenburgische Technische Universität Cottbus.
    Interaction of a rotational motion and an axial flow in small geometries for a Taylor-Couette problem2005Inngår i: Journal of Fluids and Structures, ISSN 0889-9746, E-ISSN 1095-8622, Vol. 20, nr 5, s. 621-641Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We analyze the stability of a Taylor-Couette flow under the imposition of a weak axial flow in the case of a very short cylinder with a narrow annulus gap. We consider an incompressible viscous fluid contained in the narrow gap between two concentric short cylinders, in which the inner cylinder rotates with constant angular velocity. The caps of the cylinders have narrow tubes conically tapering to very narrow slits, allowing an axial flow along the surface of the inner cylinder. The approximated solution for the Taylor-Couette flow for short cylinders was found and used for the stability analysis instead of the precise but bulky solution. The sensitivity of the Taylor-Couette flow to small perturbations and to weak axial flow was studied. We demonstrate that perturbations coming from the axial flow cause the propagation of dispersive waves in the Taylor-Couette flow. While in long cylinders the presence of an axial flow leads to the breaking of axial symmetry, in small cylinders it leads to the breaking of mirror symmetry. The coexistence of a rotation and an axial flow requires that, in addition to the energy and the angular momentum of the flow, the helicity must also be studied. The approximated form for the helicity formula in the case of short cylinders was derived. We found that the axial flow stabilizes the Taylor-Couette flow. The supercritical flow includes a rich variety of vortical structures, including a symmetric pair of Taylor vortices, an anomalous single vortex and quasiperiodic oscillating vortices. Pattern formation was studied at large for rated ranges of azimuthal and axial Reynolds numbers. A region where three branches of different states occur was localized. Numerical simulations in 3-D and in the axisymmetrical case of the model flow are presented, which illustrate the instabilities analyzed.

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