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  • 1.
    Ahlberg, Jörgen
    et al.
    Linköping University, Department of Electrical Engineering, Image Coding. Linköping University, The Institute of Technology. Div. of Sensor Technology, Swedish Defence Research Agency, Linköping, Sweden.
    Forchheimer, Robert
    Linköping University, Department of Electrical Engineering, Image Coding. Linköping University, The Institute of Technology.
    Face tracking for model-based coding and face animation2003In: International journal of imaging systems and technology (Print), ISSN 0899-9457, E-ISSN 1098-1098, Vol. 13, no 1, p. 8-22Article in journal (Refereed)
    Abstract [en]

    We present a face and facial feature tracking system able to extract animation parameters describing the motion and articulation of a human face in real-time on consumer hardware. The system is based on a statistical model of face appearance and a search algorithm for adapting the model to an image. Speed and robustness is discussed, and the system evaluated in terms of accuracy.

  • 2.
    Ajma, Muhammad
    et al.
    Linköping University, Department of Electrical Engineering, Information Coding. Linköping University, The Institute of Technology.
    Furdek, Marija
    School of Information and Communication Technology, KTH Royal Institute of Technology, Stockholm, Sweden / Faculty of Electrical Engineering and Computing, Dept. of Telecommunications, University of Zagreb, Croatia.
    Monti, Paolo
    School of Information and Communication Technology, KTH Royal Institute of Technology, Stockholm, Sweden.
    Wosinska, Lena
    School of Information and Communication Technology, KTH Royal Institute of Technology, Stockholm, Sweden.
    Forchheimer, Robert
    Linköping University, Department of Electrical Engineering, Information Coding. Linköping University, The Institute of Technology.
    Dynamic provisioning utilizing redundant modules in elastic optical networks based on architecture on demand nodes2014In: European Conference on Optical Communication (ECOC), 2014, IEEE , 2014, p. 1-3Conference paper (Refereed)
    Abstract [en]

    Survivable synthetic ROADMs are equipped with redundant switching modules to support failure recovery. The paper proposes a dynamic connection provisioning strategy which exploits these idle redundant modules to provision regular traffic resulting in a substantial improvement in the blocking performance.

  • 3.
    Ajmal, Muhammad
    et al.
    Linköping University, Department of Electrical Engineering, Information Coding. Linköping University, The Institute of Technology.
    Cavdar, Cicek
    Royal Institute of Technology, KTH, Stockholm, Sweden.
    Wosinska, Lena
    Royal Institute of Technology, KTH, Stockholm, Sweden.
    Forchheimer, Robert
    Linköping University, Department of Electrical Engineering, Information Coding. Linköping University, The Institute of Technology.
    Trading Quality of Transmission for Improved Blocking Performance in All-Optical Networks2013In: Asia Communications and Photonics Conference 2013, 2013, p. AF4E.5-Conference paper (Refereed)
    Abstract [en]

    We propose a connection provisioning strategy in dynamic all-optical networks, which exploit the possibility to allow a tolerable signal quality degradation during a small fraction of holding-time resulting in a significant improvement of blocking performance.

  • 4.
    Ajmal, Muhammad
    et al.
    Linköping University, Department of Electrical Engineering, Information Coding. Linköping University, The Institute of Technology.
    Furdek, Marija
    Royal Institute of Technology, KTH, Stockholm, Sweden / Dept. of Telecommunications, University of Zagreb, Croatia.
    Monti, Paolo
    Royal Institute of Technology, KTH, Stockholm, Sweden.
    Wosinska, Lena
    Royal Institute of Technology, KTH, Stockholm, Sweden.
    Forchheimer, Robert
    Linköping University, Department of Electrical Engineering, Information Coding. Linköping University, The Institute of Technology.
    An Optimization Model for Dynamic Bulk Provisioning in Elastic Optical Networks2014In: Asia Communications and Photonics Conference 2014, Optics Info Base, Optical Society of America, 2014, p. AF3E.6-Conference paper (Refereed)
    Abstract [en]

    We investigate benefits of setup-delay tolerance in elastic optical networks and propose an optimization model for dynamic and concurrent connection provisioning. Simulation shows that the proposed strategy offers significant improvement of the network blocking performance.

  • 5.
    Ajmal, Muhammad
    et al.
    Linköping University, Department of Electrical Engineering, Information Coding. Linköping University, The Institute of Technology.
    Zervas, Georgios
    High-Performance Networks Group, University of Bristol, UK.
    Saridis, George
    High-Performance Networks Group, University of Bristol, UK.
    Salas, Emilio H.
    High-Performance Networks Group, University of Bristol, UK.
    Simeonidou, Dimitra
    High-Performance Networks Group, University of Bristol, UK.
    Forchheimer, Robert
    Linköping University, Department of Electrical Engineering, Information Coding. Linköping University, The Institute of Technology.
    Flexible and Synthetic SDM Networks with Multi-core-Fibers Implemented by Programmable ROADMs2014In: Proceedings of European Conference on Optical Communication ECOC2014, Cannes, France, September 21-25 September 2014, IEEE , 2014, p. 1-3Conference paper (Refereed)
    Abstract [en]

    This study looks into network planning issues for synthetic MCF-based SDM networks implemented through programmable ROADMs. The results show that significant savings in switching modules and energy can be attained by exploiting the flexibility inherent in programmable ROADM through a proper network design.

  • 6.
    Ajmal, Muhammad
    et al.
    Linköping University, Department of Electrical Engineering, Information Coding. Linköping University, The Institute of Technology.
    Zervas, Georgios
    High-Performance Networks Group, University of Bristol, UK.
    Simeonidou, Dimitra
    High-Performance Networks Group, University of Bristol, UK.
    Forchheimer, Robert
    Linköping University, Department of Electrical Engineering, Information Coding. Linköping University, The Institute of Technology.
    Routing, Spectrum and Core Allocation in Flexgrid SDM Networks with Multi-core Fibers2014In: 2014 INTERNATIONAL CONFERENCE ON OPTICAL NETWORK DESIGN AND MODELING, IEEE , 2014, p. 192-197Conference paper (Refereed)
    Abstract [en]

    Space division multiplexing (SDM) over multi-core fiber (MCF) is advocated as a promising technology to overcome the capacity limit of the current single-core optical networks. However, employing the MCF for flexgrid networks necessitates the development of new concepts, such as routing, spectrum and core allocation (RSCA) for traffic demands. The introduction of MCF in the networks mitigates the spectrum continuity constraint of the routing and spectrum assignment (RSA) problem. In fact cores can be switched freely on different links during routing of the network traffic. Similarly, the route disjointness for demands with same allocated spectrum diminishes to core disjointness at the link level. On the other hand, some new issues such as the inter-core crosstalk should be taken into account while solving the RSCA problem. This paper formulates the RSCA network planning problem using the integer linear programming (ILP) formulation. The aim is to optimally minimize the maximum number of spectrum slices required on any core of MCF of a flexgrid SDM network. Furthermore, a scalable and effective heuristic is proposed for the same problem and its performance is compared with the optimal solution. The results show that the proposed algorithm is able to well approximate the optimal solution based on ILP model.

  • 7.
    Anders, A.
    et al.
    Combitech AB.
    Forchheimer, Robert
    Linköping University, Department of Electrical Engineering. Linköping University, The Institute of Technology.
    High speed and high dynamic range difference imaging based on the near sensor image processing concept2009In: Proceedings of SPIE - The International Society for Optical Engineering, ISSN 0277-786X, Vol. 7249, p. 72490G-Article in journal (Refereed)
    Abstract [en]

    The paper describes the Near Sensor Image Processing (NSIP) paradigm developed in the early 1990s and shows that it was a precursor to recent architectures proposed for direct (in the sensor) image processing and high dynamic range (HDR) image sensing. Both of these architectures are based on the specific properties of CMOS light sensors, in particular the ability to continuously monitor the accumulation of photon-induced charge as a function of time. We further propose an extension of the original NSIP pixel to include a circuit that facilitates temporal and spatio-temporal processing.

  • 8.
    Anders, Åström
    et al.
    Combitech AB, Linköping, Sweden .
    Forchheimer, Robert
    Linköping University, Department of Electrical Engineering, Information Coding. Linköping University, The Institute of Technology.
    A High Speed 2D Time-to-Impact Algorithm Targeted for Smart Image Sensors2014In: Proc. SPIE 9022, Image Sensors and Imaging Systems 2014, International Society for Optical Engineering; 1999 , 2014, Vol. 9022Conference paper (Refereed)
    Abstract [en]

    In this paper we present a 2D extension of a previously described 1D method for a time-to-impact sensor [5][6]. As in the earlier paper, the approach is based on measuring time instead of the apparent motion of points in the image plane to obtain data similar to the optical flow. The specific properties of the motion field in the time-to-impact application are used, such as using simple feature points which are tracked from frame to frame. Compared to the 1D case, the features will be proportionally fewer which will affect the quality of the estimation. We give a proposal on how to solve this problem. Results obtained are as promising as those obtained from the 1D sensor.

  • 9.
    Andersson, Kenneth
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Biomedical Engineering, Medical Informatics.
    Andersson, Mats
    Linköping University, The Institute of Technology. Linköping University, Department of Biomedical Engineering, Medical Informatics. Linköping University, Center for Medical Image Science and Visualization, CMIV.
    Johansson, Peter
    ISY LiTH.
    Forchheimer, Robert
    Linköping University, Department of Electrical Engineering.
    Knutsson, Hans
    Linköping University, The Institute of Technology. Linköping University, Department of Biomedical Engineering, Medical Informatics. Linköping University, Center for Medical Image Science and Visualization, CMIV.
    Motion compensation using backward prediction and prediction refinement2003In: Signal Processing: Image Communication, ISSN 0923-5965, Vol. 18, no 5, p. 381-400Article in journal (Refereed)
    Abstract [en]

    This paper presents new methods for use of dense motion fields for motion compensation of interlaced video. The motion estimation is based on previously decoded field-images. The motion is then temporally predicted and used for motion compensated prediction of the field-image to be coded. The motion estimation algorithm is phase-based and uses two or three field-images to achieve motion estimates with sub-pixel accuracy. To handle non-constant motion and the specific characteristics of the field-image to be coded, the initially predicted image is refined using forward motion compensation, based on block-matching. Tests show that this approach achieves higher PSNR than forward block-based motion estimation, when coding the residual with the same coder. The subjective performance is also better.

  • 10.
    Andersson, Kenneth
    et al.
    Linköping University, Department of Biomedical Engineering, Medical Informatics. Linköping University, The Institute of Technology.
    Johansson, Peter
    Linköping University, Department of Electrical Engineering, Image Coding. Linköping University, The Institute of Technology.
    Forchheimer, Robert
    Linköping University, Department of Electrical Engineering, Image Coding. Linköping University, The Institute of Technology.
    Knutsson, Hans
    Linköping University, Department of Biomedical Engineering, Medical Informatics. Linköping University, The Institute of Technology. Linköping University, Center for Medical Image Science and Visualization (CMIV).
    Backward-forward motion compensated prediction2002In: Proceedings of ACIVS 2002 (Advanced Concepts for Intelligent Vision Systems), Ghent, Belgium, September 9-11, 2002, 2002, p. 260-267Conference paper (Refereed)
    Abstract [en]

    This paper presents new methods for use of dense motion fields for motion compensation of interlaced video. The motion is estimated using previously decoded field-images. An initial motion compensated prediction is produced using the assumption that the motion is predictable in time. The motion estimation algorithm is phase-based and uses two or three field-images to achieve motion estimates with sub-pixel accuracy. To handle non-constant motion and the specific characteristics of the field-image to be coded, the initially predicted image is refined using forward motion compensation, based on block-matching. Tests show that this approach achieves higher PSNR than forward block-based motion estimation, when coding the residual with the same coder. The subjective performance is also better.

  • 11.
    Andersson, Peter
    et al.
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Forchheimer, Robert
    Linköping University, Department of Electrical Engineering. Linköping University, The Institute of Technology.
    Tehrani, Payman
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Berggren, Magnus
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Printable All-Organic Electrochromic Active-Matrix Displays2007In: Advanced Functional Materials, ISSN 1616-301X, E-ISSN 1616-3028, Vol. 17, no 16, p. 3074-3082Article in journal (Refereed)
    Abstract [en]

    All-organic active matrix addressed displays based on electrochemical smart pixels made on flexible substrates are reported. Each individual smart pixel device combines an electrochemical transistor with an electrochromic display cell, thus resulting in a low-voltage operating and robust display technology. Poly(3,4-ethylenedioxythiophene) (PEDOT) doped with poly(styrenesulfonate) (PSS) served as the active material in the electrochemical smart pixels, as well as the conducting lines, of the monolithically integrated active-matrix display. Different active-matrix display addressing schemes have been investigated and a matrix display fill factor of 65 % was reached. This is achieved by combining a three-terminal electrochemical transistor with an electrochromic display cell architecture, in which an additional layer of PEDOT:PSS was placed on top of the display cell counter electrode. In addition, we have evaluated different kinds of electrochromic polymer materials aiming at reaching a high color switch contrast. This work has been carried out in the light of achieving a robust display technology that is easily manufactured using a standard label printing press, which forced us to use the fewest different materials as well as avoiding exotic and complex device architectures. Together, this yields a manufacturing process of only five discrete patterning steps, which in turn promise for that the active matrix addressed displays can be manufactured on paper or plastic substrates in a roll-to-roll production procedure.

  • 12.
    Andersson, Peter
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Science and Technology.
    Tehrani, Payman
    Linköping University, The Institute of Technology. Linköping University, Department of Science and Technology.
    Forchheimer, Robert
    Linköping University, Department of Electrical Engineering.
    Nilsson, David
    Linköping University, The Institute of Technology. Linköping University, Department of Science and Technology.
    Robinson, Nathaniel D
    Linköping University, The Institute of Technology. Linköping University, Department of Science and Technology.
    Berggren, Magnus
    Linköping University, The Institute of Technology. Linköping University, Department of Science and Technology.
    All-Organic Active Matrix Addressed Displays Based on Electrochromic Polymers and Flexible Substrate2005In: MRS Fall Meeting,2005, 2005Conference paper (Refereed)
  • 13.
    Asplund, Maria
    et al.
    Neuronic Engineering, School of Technology and Health, Royal Institute of Technology, Alfred Nobels Allé 10, 146 57 Huddinge, Stockholm, Sweden.
    Hamedi, Mahiar
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics . Linköping University, The Institute of Technology.
    Forchheimer, Robert
    Linköping University, Department of Electrical Engineering, Image Coding. Linköping University, The Institute of Technology.
    Inganäs, Olle
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics . Linköping University, The Institute of Technology.
    Holst, Hans von
    Neuronic Engineering, School of Technology and Health, Royal Institute of Technology, Alfred Nobels Allé 10, 146 57 Huddinge, Stockholm, Sweden/Division of Clinical Neuroscience, Section Neurosurgery, Karolinska Institutet, Stockholm, Sweden.
    Construction of wire electrodesand 3D woven logicas a potential technology forneuroprosthetic implants2008In: IEEE Transactions on Biomedical Engineering, ISSN 0018-9294, E-ISSN 1558-2531Article in journal (Other academic)
    Abstract [en]

    New strategies to improve neuron coupling to neuroelectronic implants are needed. In particular, tomaintain functional coupling between implant and neurons, foreign body response like encapsulation must meminimized. Apart from modifying materials to mitigate encapsulation it has been shown that with extremely thinstructures, encapsulation will be less pronounced. We here utilize wire electrochemical transistors (WECTs) usingconducting polymer coated fibers. Monofilaments down to 10 μm can be successfully coated and weaved intocomplex networks with built in logic functions, so called textile logic. Such systems can control signal patterns at alarge number of electrode terminals from a few addressing fibres. Not only is fibre size in the range where lessencapsulation is expected but textiles are known to make successful implants because of their soft and flexiblemechanical properties. Further, textile fabrication provides versatility and even three dimensional networks arepossible. Three possible architectures for neuroelectronic systems are discussed. WECTs are sensitive to dehydrationand materials for better durability or improved encapsulation is needed for stable performance in biologicalenvironments.

  • 14.
    Astrom, Anders
    et al.
    Combitech AB, Linköping, Sweden .
    Forchheimer, Robert
    Linköping University, Department of Electrical Engineering, Information Coding. Linköping University, The Institute of Technology.
    Low-complexity, high-speed, and high-dynamic range time-to-impact algorithm2012In: Journal of Electronic Imaging (JEI), ISSN 1017-9909, E-ISSN 1560-229X, Vol. 21, no 4Article in journal (Refereed)
    Abstract [en]

    We present a method suitable for a time-to-impact sensor. Inspired by the seemingly "low" complexity of small insects, we propose a new approach to optical flow estimation that is the key component in time-to-impact estimation. The approach is based on measuring time instead of the apparent motion of points in the image plane. The specific properties of the motion field in the time-to-impact application are used, such as measuring only along a one-dimensional (1-D) line and using simple feature points, which are tracked from frame to frame. The method lends itself readily to be implemented in a parallel processor with an analog front-end. Such a processing concept [near-sensor image processing (NSIP)] was described for the first time in 1983. In this device, an optical sensor array and a low-level processing unit are tightly integrated into a hybrid analog-digital device. The high dynamic range, which is a key feature of NSIP, is used to extract the feature points. The output from the device consists of a few parameters, which will give the time-to-impact as well as possible transversal speed for off-centered viewing. Performance and complexity aspects of the implementation are discussed, indicating that time-to-impact data can be achieved at a rate of 10 kHz with todays technology.

  • 15.
    Berggren, Magnus
    et al.
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, The Institute of Technology.
    Forchheimer, Robert
    Linköping University, Department of Electrical Engineering, Information Coding. Linköping University, The Institute of Technology.
    Bobacka, Johan
    Åbo Akademi.
    Svensson, Per-Olof
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, The Institute of Technology.
    Nilsson, David
    Acreo AB.
    Larsson, Oscar
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, The Institute of Technology.
    Ivaska, Ari
    Åbo Akademi.
    PEDOT: PSS-Based Electrochemical Transistors for Ion-to-Electron Transduction and Sensor Signal Amplification2008In: Organic Semiconductors in Sensor Applications / [ed] D.A. Bernards, R. Owens, G. Malliaras, Springer, 2008, 1, p. 263-280Chapter in book (Other academic)
    Abstract [en]

    The chapter reports the use of organic electrochemical transistors in sensor applications. These transistors are excellent ion-to-electron transducers and can serve as very sensitive transducers in amperometric sensor applications. To further improve their sensitivity, we outline various amplification circuits all realized in organic electrochemical transistors.

  • 16.
    Berggren, Magnus
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Science and Technology.
    Hennerdal, Lars-Olov
    Nilsson, David
    Linköping University, The Institute of Technology. Linköping University, Department of Science and Technology.
    Sawatdee, Anurak
    Forchheimer, Robert
    Linköping University, Department of Electrical Engineering.
    Robinson, Nathaniel D
    Linköping University, The Institute of Technology. Linköping University, Department of Science and Technology.
    Printed Integrated Electronic and Electrochemical Systems on Paper2005In: MRS Fall Meeting,2005, 2005Conference paper (Refereed)
  • 17.
    Fabiano, Simone
    et al.
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, The Institute of Technology.
    Usta, Hakan
    Polyera Corp, IL 60077 USA; Abdullah Gul University, Turkey.
    Forchheimer, Robert
    Linköping University, Department of Electrical Engineering, Information Coding. Linköping University, The Institute of Technology.
    Crispin, Xavier
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, The Institute of Technology.
    Facchetti, Antonio
    Polyera Corp, IL 60077 USA.
    Berggren, Magnus
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, The Institute of Technology.
    Selective Remanent Ambipolar Charge Transport in Polymeric Field-Effect Transistors For High-Performance Logic Circuits Fabricated in Ambient2014In: Advanced Materials, ISSN 0935-9648, E-ISSN 1521-4095, Vol. 26, no 44, p. 7438-7443Article in journal (Refereed)
    Abstract [en]

    n/a

  • 18.
    Forchheimer, Daniel
    et al.
    Royal Institute Technology KTH, Sweden.
    Forchheimer, Robert
    Linköping University, Department of Electrical Engineering, Information Coding. Linköping University, The Institute of Technology.
    Haviland, David B.
    Royal Institute Technology KTH, Sweden.
    Improving image contrast and material discrimination with nonlinear response in bimodal atomic force microscopy2015In: Nature Communications, ISSN 2041-1723, E-ISSN 2041-1723, Vol. 6, no 6270Article in journal (Refereed)
    Abstract [en]

    Atomic force microscopy has recently been extented to bimodal operation, where increased image contrast is achieved through excitation and measurement of two cantilever eigen-modes. This enhanced material contrast is advantageous in analysis of complex heterogeneous materials with phase separation on the micro or nanometre scale. Here we show that much greater image contrast results from analysis of nonlinear response to the bimodal drive, at harmonics and mixing frequencies. The amplitude and phase of up to 17 frequencies are simultaneously measured in a single scan. Using a machine-learning algorithm we demonstrate almost threefold improvement in the ability to separate material components of a polymer blend when including this nonlinear response. Beyond the statistical analysis performed here, analysis of nonlinear response could be used to obtain quantitative material properties at high speeds and with enhanced resolution.

  • 19.
    Forchheimer, Robert
    et al.
    Linköping University, Department of Electrical Engineering. Linköping University, The Institute of Technology.
    Wosinska, Lena
    Royal Institute of Technology, KTH, Stockholm, Sweden.
    Monti, Paolo
    Royal Institute of Technology, KTH, Stockholm, Sweden.
    An Optical Overlay Network Concept for Hard QoS Requirements2009Conference paper (Refereed)
    Abstract [en]

    It has long been argued that the best-effort strategy on which Internet is based will limit its use for real-time applications such as video or telephony. However, it has been shown that such services can indeed tolerate some jitter and rate variations through various error resilience and concealment techniques. Despite of that the Internet infrastructure is continuously upgraded with higher performance components, which further reduce the transmission problems; still there are certain classes of applications that undoubtedly will need new transmission paradigms. An example is the remote control of an industrial process that may require jitter levels down to a few microseconds. Another example is quantum cryptography where an optical transparent path between sender and receiver is to be established. In this paper we present a concept based on an optical overlay network infrastructure. This network concept can be applied in an incremental way and will enable the current network infrastructure to handle demands with such extreme QoS requirements.

  • 20. Fratarcangeli, M.
    et al.
    Schaerf, M.
    University of Rome La Sapienza, Department of Computer and Systems Science, Via Salaria 113, 00196 Rome, Italy.
    Forchheimer, Robert
    Linköping University, The Institute of Technology. Linköping University, Department of Electrical Engineering.
    Facial motion cloning with radial basis functions in MPEG-4 FBA2007In: Graphical Models, ISSN 1524-0703, E-ISSN 1524-0711, Vol. 69, no 2, p. 106-118Article in journal (Refereed)
    Abstract [en]

    Facial Motion Cloning (FMC) is the technique employed to transfer the motion of a virtual face (namely the source) to a mesh representing another face (the target), generally having a different geometry and connectivity. In this paper, we describe a novel method based on the combination of the Radial Basis Functions (RBF) volume morphing with the encoding capabilities of the widely used MPEG-4 Facial and Body Animation (FBA) international standard. First, we find the morphing function G(P) that precisely fits the shape of the source into the shape of the target face. Then, all the MPEG-4 encoded movements of the source face are transformed using the same function G(P) and mapped to the corresponding vertices of the target mesh. By doing this, we obtain, in a straightforward and simple way, the whole set of the MPEG-4 encoded facial movements for the target face in a short time. This animatable version of the target face is able to perform generic face animation stored in a MPEG-4 FBA data stream. © 2006 Elsevier Inc. All rights reserved.

  • 21.
    Hamedi, Mahiar
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics . Linköping University, The Institute of Technology.
    Forchheimer, Robert
    Linköping University, Department of Electrical Engineering, Image Coding. Linköping University, The Institute of Technology.
    Inganäs, Olle
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics . Linköping University, The Institute of Technology.
    Towards woven logic from organic electronic fibres2007In: Nature Materials, ISSN 1476-1122, E-ISSN 1476-4660, Vol. 6, p. 357-362Article in journal (Refereed)
    Abstract [en]

    The use of organic polymers for electronic functions is mainly motivated by the low-end applications, where low cost rather than advanced performance is a driving force. Materials and processing methods must allow for cheap production. Printing of electronics using inkjets1 or classical printing methods has considerable potential to deliver this. Another technology that has been around for millennia is weaving using fibres. Integration of electronic functions within fabrics, with production methods fully compatible with textiles, is therefore of current interest, to enhance performance and extend functions of textiles2. Standard polymer field-effect transistors require well defined insulator thickness and high voltage3, so they have limited suitability for electronic textiles. Here we report a novel approach through the construction of wire electrochemical transistor (WECT) devices, and show that textile monofilaments with 10–100 µm diameters can be coated with continuous thin films of the conducting polythiophene poly(3,4-ethylenedioxythiophene), and used to create micro-scale WECTs on single fibres. We also demonstrate inverters and multiplexers for digital logic. This opens an avenue for three-dimensional polymer micro-electronics, where large-scale circuits can be designed and integrated directly into the three-dimensional structure of woven fibres.

  • 22.
    Johansson, Peter
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Electrical Engineering, Image Coding.
    Forchheimer, Robert
    Linköping University, Department of Electrical Engineering.
    Source Coding Rate Control for Gilbert-Elliott Channel2005In: RVK 05,2005, Linköping: FOI , 2005, p. 543-Conference paper (Refereed)
    Abstract [en]

    We consider the problem of choosing the rate for a source coder when transmitting lossy-compressed data in real-time over a channel with time-varying rate. The goal for the rate selection is to obtain a low average distortion while obeying a real-time constraint. We formulate the real-time constraint in terms of a limited buffer size. A few strategies for rate-control are suggested and evaluated for a Gilbert-Elliott type channel model. The results are also compared to a theoretical upper bound on performance for a rate-control algorithm working with constraints on buffer size.

  • 23. Klasen, L.
    et al.
    Li, H.
    Forchheimer, Robert
    Linköping University, The Institute of Technology. Linköping University, Department of Electrical Engineering.
    Evaluation of a method for invariant and automated detection and tracking of objects from video2001In: Proceedings of SPIE, the International Society for Optical Engineering, ISSN 0277-786X, E-ISSN 1996-756X, Vol. 4232, p. 455-463Conference paper (Other academic)
    Abstract [en]

    Video generates a rich set of image information and often the useful information is only a very limited set of the available information. Another well-known fact is that visually reviewing of long video recordings is a time demanding task. In combination with the continuously increasing number of video surveillance systems, this leads to an increasing need for automated analysis of long image sequences. The goal for this work is to develop and evaluate a method for automatic detection and tracking of events recorded onto a surveillance video, such as appearance of persons or vehicles in a surveyed area, to evaluate the usefulness for forensic applications and real time applications. One core problem is the fact that both the background and the objects move, where only the physical motion of moving objects are of interest and needs to be separated from the camera motion. Another core problem in many of the video processing algorithms is parameter estimation despite invariance for accurate modeling of the desired features. Varying scale, color, lightning conditions and occlusion of the object of interest can for example cause invariance. The technical approaches for this work is to separate global and local motion by analyzing the optical flow constraints. To overcome the problem caused by such feature and object invariance, all pixels are considered independently and no feature parameters are needed. If the basic optical flow constraint is satisfied, the motion is classified as global motion. If not, the motion is considered caused by local motion, noise or other phenomena. An object that undergoes local motion can then be detected and tracked as is forms a trace in the temporal domain, while the noise appears on an intermittent basis and will be disregarded. The results from applying this method on several image sequences were compared and the robustness and ability to deal with invariance has been evaluated. The result clearly shows that in realistic situations, where visual reviewing can be quite a difficult task, computer based methods for automatic detection are useful to detected moving objects in long video recordings.

  • 24.
    Laiho, Ari
    et al.
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Herlogsson, Lars
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Forchheimer, Robert
    Linköping University, Department of Electrical Engineering. Linköping University, The Institute of Technology.
    Crispin, Xavier
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Berggren, Magnus
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, The Institute of Technology.
    Controlling the dimensionality of charge transport in organic thin-film transistors2011In: Proceedings of the National Academy of Sciences of the United States of America, ISSN 0027-8424, E-ISSN 1091-6490, Vol. 108, no 37, p. 15069-15073Article in journal (Refereed)
    Abstract [en]

    Electrolyte-gated organic thin-film transistors (OTFTs) can offer a feasible platform for future flexible, large-area and low-cost electronic applications. These transistors can be divided into two groups on the basis of their operation mechanism: (i) field-effect transistors that switch fast but carry much less current than (ii) the electrochemical transistors which, on the contrary, switch slowly. An attractive approach would be to combine the benefits of the field-effect and the electrochemical transistors into one transistor that would both switch fast and carry high current densities. Here we report the development of a polyelectrolyte-gated OTFT based on conjugated polyelectrolytes, and we demonstrate that the OTFTs can be controllably operated either in the field-effect or the electrochemical regime. Moreover, we show that the extent of electrochemical doping can be restricted to a few monolayers of the conjugated polyelectrolyte film, which allows both high current densities and fast switching speeds at the same time. We propose an operation mechanism based on self-doping of the conjugated polyelectrolyte backbone by its ionic side groups.

  • 25.
    Larsson, Jan-Åke
    et al.
    Linköping University, Department of Mathematics, Applied Mathematics. Linköping University, The Institute of Technology.
    Wadströmer, Niclas
    Linköping University, Department of Electrical Engineering. Linköping University, The Institute of Technology.
    Hermanson, Ola
    Karolinska Institute.
    Lendahl, Urban
    Karolinska Institute.
    Forchheimer, Robert
    Linköping University, Department of Electrical Engineering. Linköping University, The Institute of Technology.
    Modelling cell lineage using a meta-Boolean tree model with a relation to gene regulatory networks2011In: JOURNAL OF THEORETICAL BIOLOGY, ISSN 0022-5193, Vol. 268, no 1, p. 62-76Article in journal (Refereed)
    Abstract [en]

    A cell lineage is the ancestral relationship between a group of cells that originate from a single founder cell. For example, in the embryo of the nematode Caenorhabditis elegans an invariant cell lineage has been traced, and with this information at hand it is possible to theoretically model the emergence of different cell types in the lineage, starting from the single fertilized egg. In this report we outline a modelling technique for cell lineage trees, which can be used for the C. elegans embryonic cell lineage but also extended to other lineages. The model takes into account both cell-intrinsic (transcription factor-based) and -extrinsic (extracellular) factors as well as synergies within and between these two types of factors. The model can faithfully recapitulate the entire C. elegans cell lineage, but is also general, i.e., it can be applied to describe any cell lineage. We show that synergy between factors, as well as the use of extrinsic factors, drastically reduce the number of regulatory factors needed for recapitulating the lineage. The model gives indications regarding co-variation of factors, number of involved genes and where in the cell lineage tree that asymmetry might be controlled by external influence. Furthermore, the model is able to emulate other (Boolean, discrete and differential-equation-based) models. As an example, we show that the model can be translated to the language of a previous linear sigmoid-limited concentration-based model (Geard and Wiles, 2005). This means that this latter model also can exhibit synergy effects, and also that the cumbersome iterative technique for parameter estimation previously used is no longer needed. In conclusion, the proposed model is general and simple to use, can be mapped onto other models to extend and simplify their use, and can also be used to indicate where synergy and external influence would reduce the complexity of the regulatory process.

  • 26.
    Löfvenberg, Jacob
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Electrical Engineering, Information Theory.
    Johansson, Peter
    Linköping University, The Institute of Technology. Linköping University, Department of Electrical Engineering, Image Coding.
    Forchheimer, Robert
    Linköping University, Department of Electrical Engineering.
    A Model for Mobility-Based Communication in Ad Hoc Networks2005In: The Third Swedish National Computer Networking Workshop,2005, 2005Conference paper (Other academic)
    Abstract [en]

    We introduce the concept of mobility-based communication in ad hoc networks, meaning that the packet transport is performed mainly by the nodes' movement. We outline a model for such networks, utilizing a stochastic model for the geographical location of the nodes. A test case is defined in which three strategies for packet forwarding are presented and evaluated.

  • 27. Mannerbro, R.
    et al.
    Ranlöf, Magnus
    Linköping University, The Institute of Technology. Linköping University, Department of Science and Technology.
    Robinson, Nathaniel D
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry .
    Forchheimer, Robert
    Linköping University, The Institute of Technology. Linköping University, Department of Electrical Engineering.
    Inkjet printed electrochemical organic electronics2008In: Synthetic metals, ISSN 0379-6779, E-ISSN 1879-3290, Vol. 158, no 13, p. 556-560Article in journal (Refereed)
    Abstract [en]

    A conventional desktop inkjet printer has been used as a combined deposition and patterning tool of electrochemical organic transistors on rough flexible carriers. The functionality of these devices rely upon redox reactions occurring at the interface between a conjugated polymer film and an electrolyte. Both the electrolyte and the conjugated polymer suspension (an aqueous dispersion of poly(3,4-ethylenedioxythiophene):poly(styrene sulphonic acid)) were additively patterned with the inkjet printer, making the electrochemical device all-inkjet printed. Basic implementations of the transistor in simple electrochemical logical circuitry have been produced. The printing technique can be anticipated to be used for the production of small series of devices based on the electrochemical technology discussed. © 2008 Elsevier B.V. All rights reserved.

  • 28.
    Markus, Nenad
    et al.
    University of Zagreb, Croatia .
    Frljak, Miroslav
    University of Zagreb, Croatia .
    Pandzic, Igor S.
    University of Zagreb, Croatia .
    Ahlberg, Jörgen
    Linköping University, Department of Electrical Engineering, Information Coding. Linköping University, The Institute of Technology.
    Forchheimer, Robert
    Linköping University, Department of Electrical Engineering, Information Coding. Linköping University, The Institute of Technology.
    Eye pupil localization with an ensemble of randomized trees2014In: Pattern Recognition, ISSN 0031-3203, E-ISSN 1873-5142, Vol. 47, no 2, p. 578-587Article in journal (Refereed)
    Abstract [en]

    We describe a method for eye pupil localization based on an ensemble of randomized regression trees and use several publicly available datasets for its quantitative and qualitative evaluation. The method compares well with reported state-of-the-art and runs in real-time on hardware with limited processing power, such as mobile devices.

  • 29.
    Markuš, Nenad
    et al.
    University of Zagreb, Faculty of Electrical Engineering and Computing, Zagreb, Croatia.
    Frljak, Miroslav
    University of Zagreb, Faculty of Electrical Engineering and Computing, Zagreb, Croatia.
    Pandžić, Igor
    University of Zagreb, Faculty of Electrical Engineering and Computing, Zagreb, Croatia.
    Ahlberg, Jörgen
    Linköping University, Department of Electrical Engineering, Computer Vision. Linköping University, Faculty of Science & Engineering.
    Forchheimer, Robert
    Linköping University, Department of Electrical Engineering, Information Coding. Linköping University, Faculty of Science & Engineering.
    High-performance face tracking2012Conference paper (Refereed)
    Abstract [en]

    Face tracking is an extensively studied field. Nevertheless, it is still a challenge to make a robust and efficient face tracker, especially on mobile devices. This extended abstract briefly describes our implementation of a high-performance multi-platform face and facial feature tracking system. The main characteristics of our approach are that the tracker is fully automatic and works with the majority of faces without any manual initialization. It is robust, resistant to rapid changes in pose and facial expressions, does not suffer from drifting and is modestly computationally expensive. The tracker runs in real-time on mobile devices.

  • 30.
    Mertaniemi, Henrikki
    et al.
    Aalto University, Finland .
    Forchheimer, Robert
    Linköping University, Department of Electrical Engineering, Information Coding. Linköping University, The Institute of Technology.
    Ikkala, Olli
    Aalto University, Finland .
    Ras, Robin H A
    Aalto University, Finland .
    Rebounding Droplet-Droplet Collisions on Superhydrophobic Surfaces: from the Phenomenon to Droplet Logic2012In: Advanced Materials, ISSN 0935-9648, E-ISSN 1521-4095, Vol. 24, no 42, p. 5738-5743Article in journal (Refereed)
    Abstract [en]

    When water droplets impact each other while traveling on a superhydrophobic surface, we demonstrate that they are able to rebound like billiard balls. We present elementary Boolean logic operations and a flip-flop memory based on these rebounding water droplet collisions. Furthermore, bouncing or coalescence can be easily controlled by process parameters. Thus by the controlled coalescence of reactive droplets, here using the quenching of fluorescent metal nanoclusters as a model reaction, we also demonstrate an elementary operation for programmable chemistry.

  • 31.
    Muhammad, Ajmal
    et al.
    Linköping University, Department of Electrical Engineering, Information Coding. Linköping University, The Institute of Technology.
    Cavdar, Cicek
    Royal Institute of Technology (KTH), Stockholm, Sweden.
    Wosinska, Lena
    Royal Institute of Technology (KTH), Stockholm, Sweden.
    Forchheimer, Robert
    Linköping University, Department of Electrical Engineering, Information Coding. Linköping University, The Institute of Technology.
    Effect of Delay Tolerance in WDM Networks with Differentiated Services2011In: Optical Fiber Communication Conference and Exposition (OFC/NFOEC), 2011 and the National Fiber Optic Engineers Conference, IEEE , 2011, p. 1-3Conference paper (Refereed)
    Abstract [en]

    We study a dynamic WDM network supporting different service classes (SC) containing applications having similar setup delay tolerance. By utilizing delay tolerance we propose scheduling strategies able to significantly reduce blocking probability of each SC.

  • 32.
    Muhammad, Ajmal
    et al.
    Linköping University, Department of Electrical Engineering. Linköping University, The Institute of Technology.
    Cavdar, Cicek
    Royal Institute Technology KTH, Sweden .
    Wosinska, Lena
    Royal Institute Technology KTH, Sweden .
    Forchheimer, Robert
    Linköping University, Department of Electrical Engineering, Information Coding. Linköping University, The Institute of Technology.
    Service Differentiated Provisioning in Dynamic WDM Networks Based on Set-Up Delay Tolerance2013In: Journal of Optical Communications and Networking, ISSN 1943-0620, E-ISSN 1943-0639, Vol. 5, no 11, p. 1250-1261Article in journal (Refereed)
    Abstract [en]

    Optical networks are expected to provide a unified platform for a diverse set of emerging applications (three-dimensional TV, digital cinema, e-health, grid computing, etc). The service differentiation will be an essential feature of these networks. Considering the fact that users have different levels of patience for different network applications, referred to as set-up delay tolerance, it will be one of the key parameters for service differentiation. Service differentiation based on set-up delay tolerance will not only enable network users to select an appropriate service class (SC) in compliance with their requirements, but will also provide an opportunity to optimize the network resource provisioning by exploiting this information, resulting in an improvement in the overall performance. Improvement in network performance can be further enhanced by exploiting the connection holding-time awareness. However, when multiple classes of service with different set-up delay tolerances are competing for network resources, the connection requests belonging to SCs with higher set-up delay tolerance have better chances to grab the resources and leave less room for the others, resulting in degradation in the blocking performance of less patient customers. This study proposes different scheduling strategies for promoting the requests belonging to smaller set-up delay tolerance SCs, such as giving priority, reserving some fraction of available resources, and augmenting the research space by providing some extra paths. Extensive simulation results show that 1) priority in the rescheduling queue is not always sufficient for eradicating the degradation effect of high delay tolerant SCs on the provisioning rate of the most stringent SC, and 2) by utilizing the proposed strategies, resource efficiency and overall network blocking performance improve significantly in all SCs.

  • 33.
    Muhammad, Ajmal
    et al.
    Linköping University, Department of Electrical Engineering, Information Coding. Linköping University, The Institute of Technology.
    Forchheimer, Robert
    Linköping University, Department of Electrical Engineering, Information Coding. Linköping University, The Institute of Technology.
    Efficient Scheduling Strategies for Dynamic WDM Networks with Set-Up Delay Tolerance2013Conference paper (Refereed)
    Abstract [en]

    Emerging, on-demand applications (e.g., ultra-high definition TV, grid computing, e-health, digital cinema, etc.) will dominate the next generation optical networks. Dynamic on-demand provisioning of optical channels is advocated as a promising solution to fulfil the high bandwidth requirements of these applications. Among the various on-line strategies proposed to provision such applications, the ones exploiting the connection holding-time knowledge and the flexibility provided by the set-up delay tolerance exhibited a good potential in improving the overall network blocking performance. Considering the fact that the users are willing to wait for provisioning until their set-up delay tolerance expire, it is not of prime importance to establish connection on the earliest available resources. Rather, effective results in terms of network blocking performance can be achieved by provisioning connections on optimal instead of earliest available resources that exist within the set-up delay tolerance. This paper presents novel connection scheduling strategies that efficiently exploit the set-up delay tolerance and holding-time knowledge for dynamic wavelength division multiplexing (WDM) networks. The proposed scheme computes the set of all available provisioning opportunities (at different time instants) within set-up delay tolerance and selects the one that is most efficient in terms of network resource utilization. This scheme is investigated for two different scenarios, that are, for connection requests that cannot be provisioned at the time of their arrival due to resource unavailability and for every request irrespective of whether the required resources for set-up are available or not. Simulation results confirm that the proposed strategies attain significant improvement in network blocking probability compared to earlier presented techniques.

  • 34.
    Muhammad, Ajmal
    et al.
    Linköping University, Department of Electrical Engineering, Information Coding. Linköping University, The Institute of Technology.
    Forchheimer, Robert
    Linköping University, Department of Electrical Engineering, Information Coding. Linköping University, The Institute of Technology.
    Reducing Blocking Probability in Dynamic WDM Networks by Rerouting and set-up Delay Tolerance2011In: 17th IEEE International Conference on Networks (ICON), 2011, IEEE , 2011, p. 195-200Conference paper (Refereed)
    Abstract [en]

    With the emergence of bandwidth intensive applications new methodologies need to be developed for improvement of network blocking performance, without supplying extra resources in dynamic wavelength-division-multiplexing (WDM) networks. Rerouting is one among the viable and cost-effective solutions to reduce the blocking probability (BP) of optical WDM networks. Similarly, set-up delay tolerance, a metric of service level agreement (SLA) has been exploited in [1]-[3] for improvement in network BP. In this paper, we study the rerouting in dynamic WDM network and analyze two different lightpath rerouting strategies. Moreover, we investigate further improvement in network BP by exploiting these rerouting techniques for network provisioned with set-up delay tolerance. Through extensive simulation studies, we confirm that the rerouting strategies decrease the BP substantially for network provisioned with set-up delay tolerance, even for smaller set-up delay tolerance value i.e. when the connection requests are impatient to wait for provisioning in the network. However, it also reduce BP significantly even when the network is not provisioned with set-up delay tolerance.

  • 35.
    Muhammad, Ajmal
    et al.
    Linköping University, Department of Electrical Engineering, Information Coding. Linköping University, The Institute of Technology.
    Forchheimer, Robert
    Linköping University, Department of Electrical Engineering, Information Coding. Linköping University, The Institute of Technology.
    Reducing Blocking Probability in Dynamic WDM Networks Using Different Schemes2011In: Proceedings 2011 International Conferenceon the Network of the Future, 28-30 November, 2011 Paris, France, IEEE , 2011, p. 97-101Conference paper (Refereed)
    Abstract [en]

    strategies. First we analyze a strategy which effectively utilizes two Service Level Agreement (SLA) metrics i.e. holding-time combined with set-up delay tolerance, for connection provisioning. We investigate its performance improvement compared to the scheme proposed in [4] and with the strategy which exploits only the set-up delay tolerance for connection provisioning. Secondly, we evaluate the performance of the various approaches for network blocking reduction over a wide range of network loads. Our aim is to obtain an insight information, that can be useful for selection of an optimal strategy for designing a network, with specific network parameters and performance requirements.

  • 36.
    Muhammad, Ajmal
    et al.
    Linköping University, Department of Electrical Engineering, Information Coding. Linköping University, The Institute of Technology.
    Forchheimer, Robert
    Linköping University, Department of Electrical Engineering, Information Coding. Linköping University, The Institute of Technology.
    Wosinska, Lena
    Royal Institute of Technology (KTH), Stockholm, Sweden.
    Impairment-Aware Dynamic Provisioning in WDM Networks with set-up Delay Tolerance and Holding-time Awareness2011In: Proceedings of the 17th IEEE International Conference on Networks (ICON), 2011, IEEE , 2011, p. 213-218Conference paper (Refereed)
    Abstract [en]

    We study a dynamic WDM network with nonideal components in the physical layer which uses an impairment-aware routing and wavelength (RWA) algorithm for connection provisioning. We investigate the reduction in blocking probability (BP) by utilizing service Level Agreement (SLA) metric i.e. setup delay tolerance during connection provisioning. Furthermore, we explore the improvement in the network performance by efficiently utilizing the knowledge of the connections holding-time, another metric of SLA. Keeping in mind that BP reduction can be obtained by set-up delay tolerance [1] our focus is to investigate how set-up delay tolerance combined with holding-time awareness can improve BP performance caused by physical impairment. Our simulation results confirm that significant improvement can be achieved by holding-time aware connection provisioning compared to the unaware holding-time case. Moreover as expected, set-up delay tolerance can reduce BP even without knowledge of connections holding-time.

  • 37.
    Muhammad, Ajmal
    et al.
    Linköping University, Department of Electrical Engineering, Information Coding. Linköping University, The Institute of Technology.
    Johansson, Peter
    Linköping University, Department of Electrical Engineering, Computer Vision. Linköping University, The Institute of Technology.
    Forchheimer, Robert
    Linköping University, Department of Electrical Engineering. Linköping University, The Institute of Technology.
    Effect of Buffer Placement on Performance When Communicating Over a Rate-Variable Channel2009In: / [ed] Eugen Borcoci, Michel Diaz, Cosmin Dini, Reijo Savola, IEEE, 345 E 47TH ST, NEW YORK, NY 10017 USA , 2009, p. 125-130Conference paper (Refereed)
    Abstract [en]

    We compare the performance of two real-time multimedia communication systems for quality versus end-to-end delay. We develop an analytical framework for comparison when the systems use a deterministic time-varying channel. Moreover, we assess their performance for the Gilbert-Elliott channel model which alternates between a good and a bad state with time durations that are exponentially distributed. The goal of the paper is to select the best system with low average distortion while obeying a real-time constraint.

  • 38.
    Muhammad, Ajmal
    et al.
    Linköping University, Department of Electrical Engineering, Information Coding. Linköping University, The Institute of Technology.
    Zervas, Georgios
    High-Performance Networks Group, University of Bristol, Bristol, UK.
    Amaya, Norberto
    High-Performance Networks Group, University of Bristol, Bristol, UK.
    Simeonidou, Dimitra
    High-Performance Networks Group, University of Bristol, Bristol, UK.
    Forchheimer, Robert
    Linköping University, Department of Electrical Engineering, Information Coding. Linköping University, The Institute of Technology.
    Introducing Flexible and Synthetic Optical Networking: Planning and Operation Based on Network Function Programmable ROADMs2014In: Journal of Optical Communications and Networking, ISSN 1943-0620, E-ISSN 1943-0639, Vol. 6, no 7, p. 635-648Article in journal (Refereed)
    Abstract [en]

    Elastic optical networks are envisaged as promising solutions to fulfill the diverse bandwidth requirements for the emerging heterogeneous network applications. To support flexible allocation of spectrum resources the optical network nodes need to be agile. Among the different proposed solutions for elastic nodes, the one based on architecture of demand (AoD) exhibits considerable flexibility against the other alternatives. The node modules in the case of AoD are not hard-wired, but can be connected/disconnected to any input/output port according to the requirements. Thus, each AoD node and the network (fabricated with AoD nodes) as a whole acts like an optical field-programmable gate array. This flexibility inherent in AoD can be exploited for different purposes, such as for cost-efficient and energy-efficient design of the networks. This study looks into the cost-efficient network planning issue for synthetic networks implemented through AoD nodes. The problem is formalized as an integer linear programming formulation for presenting the optimal solution. Furthermore, a scalable and effective heuristic algorithm is proposed for cost-efficient design, and its performance is compared with the optimal solution. The designed networks with AoD nodes are further investigated for a dynamic scenario, and their blocking probability due to limited switching resources in the nodes is examined. To alleviate the blocking performance for the dynamic case, an efficient synthesis strategy along with a scheme for optimal placement of switching resources within the network nodes is presented. Extensive results show that 1) even at high loads, the network with AoD nodes achieves saving of switching modules up to 40% compared to the one with static reconfigurable optical add-drop multiplexers (ROADMs) through a proper network design, 2) by diminishing the spectrum selective switches the overall power consumption of the network decreases by more than 25% for high loads, and 3) for the dynamic scenario the blocking owing to the node modules constraint is alleviated significantly by slightly augmenting the switching devices and optimally deploying them within the network nodes.

  • 39.
    Muhammad, Ajmal
    et al.
    Linköping University, Department of Electrical Engineering. Linköping University, Faculty of Science & Engineering.
    Zervas, Georgios S.
    University of Bristol, England.
    Amaya, Norberto
    University of Bristol, England.
    Simeonidou, Dimitra
    University of Bristol, England.
    Forchheimer, Robert
    Linköping University, Department of Electrical Engineering, Information Coding. Linköping University, Faculty of Science & Engineering.
    Cost-Efficient Design of Flexible Optical Networks Implemented by Architecture on Demand2014In: 2014 OPTICAL FIBER COMMUNICATIONS CONFERENCE AND EXHIBITION (OFC): San Francisco, California United States 9–13 March 2014, IEEE , 2014, p. W2A.17-Conference paper (Refereed)
    Abstract [en]

    Architecture on demand (AoD) node offers considerable flexibility against traditional ROADMs. The paper presents a cost-efficient network planning strategy that exploits the flexibility inherent in AoD. Results show that AoD can save significantly in node modules through a proper network design.

  • 40.
    Muhammad, Muhammad
    et al.
    Linköping University, Department of Electrical Engineering, Information Coding. Linköping University, Faculty of Science & Engineering.
    Zervas, Georgios
    University of Bristol, England.
    Forchheimer, Robert
    Linköping University, Department of Electrical Engineering, Information Coding. Linköping University, Faculty of Science & Engineering.
    Resource Allocation for Space-Division Multiplexing: Optical White Box Versus Optical Black Box Networking2015In: Journal of Lightwave Technology, ISSN 0733-8724, E-ISSN 1558-2213, Vol. 33, no 23, p. 4928-4941Article in journal (Refereed)
    Abstract [en]

    Elastic optical networking (EON) with space-division multiplexing (SDM) is the only evident long-term solution to the capacity needs of the future networks. The introduction of space via spatial fibers, such as multicore fibers (MCF) to EON provides an additional dimension as well as challenges to the network planning and resource optimization problem. There are various types of technologies for SDM transmission medium, switching, and amplification; each of them induces different capabilities and constraints on the network. For example, employing MCF as the transmission medium for SDM mitigates the spectrum continuity constraint of the routing and spectrum allocation problem for EON. In fact, cores can be switched freely on different links during routing of the network traffic. On the other hand, intercore crosstalk should be taken into account while solving the resource allocation problem. In the framework of switching for elastic SDM network, the programmable architecture on demand (AoD) node (optical white box) can provide a more scalable solution with respect to the hard-wired reconfigurable optical add/drop multiplexers (ROADMs) (optical black box). This study looks into the routing, modulation, spectrum, and core allocation (RMSCA) problem for weakly-coupled MCF-based elastic SDM networks implemented through AoDs and static ROADMs. The proposed RMSCA strategies integrate the spectrum resource allocation, switching resource deployment, and physical layer impairment in terms of intercore crosstalk through a multiobjective cost function. The presented strategies perform a cross-layer optimization between the network and physical layers to compute the actual intercore crosstalk for the candidate resource solutions and are specifically tailored to fit the type of optical node deployed in the network. The aim of all these strategies is to jointly optimize the switching and spectrum resource efficiency when provisioning demands with diverse capacity requirements. Extensive simulation results demonstrate that 1) by exploiting the dense intranodal connectivity of the ROADM-based SDM network, resource efficiency and provisioned traffic volume improve significantly related to the AoD-based solution, 2) the intercore crosstalk aware strategies improve substantially the provisioned traffic volume for the AoD-based SDM network, and 3) the switching modules grows very gently for the network designed with AoD nodes related to the one with ROADMs as the traffic increases, qualifying AoD as a scalable and cost-efficient choice for future SDM networks.

  • 41.
    Nilsson, David
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Science and Technology.
    Forchheimer, Robert
    Linköping University, Department of Electrical Engineering.
    Berggren, Magnus
    Linköping University, The Institute of Technology. Linköping University, Department of Science and Technology.
    All organic printable logic circuits on paper substrates2004In: Material Research Society Spring Meeting,2004, 2004Conference paper (Refereed)
  • 42.
    Nilsson, David
    et al.
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Forchheimer, Robert
    Linköping University, Department of Electrical Engineering, Information Coding. Linköping University, The Institute of Technology.
    Berggren, Magnus
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, The Institute of Technology.
    Robinson, Nathaniel
    Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry. Linköping University, The Institute of Technology.
    The electrochemical transistor and circuit design considerations2005In: Proceedings of the 2005 European Conference on Circuit Theory and Design, IEEE conference proceedings, 2005, p. III/349-III/352Conference paper (Refereed)
    Abstract [en]

    The electrochemical transistor is presented from a functional point-of-view. It is shown that this transistor has characteristics that are similar to p-channel depletion-mode MOSFET devices. Electrical design rules for proper operation are given. Based on these rules, we show how logical circuits such as inverters and gates can be constructed.

  • 43.
    Nilsson, David
    et al.
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Robinson, Nathaniel
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Berggren, Magnus
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Forchheimer, Robert
    Linköping University, Department of Electrical Engineering. Linköping University, The Institute of Technology.
    Electrochemical Logic Circuits2005In: Advanced Materials, ISSN 0935-9648, Vol. 17, no 3, p. 353-358Article in journal (Refereed)
  • 44.
    Olofsson, Mikael
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Electrical Engineering, Data Transmission.
    Ericson, Thomas
    Linköping University, The Institute of Technology. Linköping University, Department of Electrical Engineering, Data Transmission.
    Forchheimer, Robert
    Linköping University, The Institute of Technology. Linköping University, Department of Electrical Engineering, Image Coding.
    Telecommunication Methods2007Other (Other (popular science, discussion, etc.))
  • 45.
    Olofsson, Mikael
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Electrical Engineering, Data Transmission.
    Ericson, Thomas
    Linköping University, The Institute of Technology. Linköping University, Department of Electrical Engineering, Data Transmission.
    Forchheimer, Robert
    Linköping University, The Institute of Technology. Linköping University, Department of Electrical Engineering, Image Coding.
    Henriksson, Ulf
    Linköping University, The Institute of Technology. Linköping University, Department of Electrical Engineering, Data Transmission.
    Basic Telecommunication2006Other (Other (popular science, discussion, etc.))
  • 46.
    Pettersson, Sofia
    et al.
    Linköping University, Department of Electrical Engineering, Information Coding. Linköping University, Faculty of Science & Engineering.
    Forchheimer, Robert
    Linköping University, Department of Electrical Engineering, Information Coding. Linköping University, Faculty of Science & Engineering.
    Larsson, Jan-Åke
    Linköping University, Department of Electrical Engineering, Information Coding. Linköping University, Faculty of Science & Engineering.
    Meta-Boolean models of asymmetric division patterns in the C. elegans intestinal lineage: Implications for the posterior boundary of intestinal twist2013In: Worm, ISSN 2162-4054, Vol. 2, article id e23701Article in journal (Refereed)
    Abstract [en]

    The intestine of Caenorhabditis elegans is derived from 20 cells that are organized into nine intestinal rings. During embryogenesis, three of the rings rotate approximately 90 degrees in a process known as intestinal twist. The underlying mechanisms for this morphological event are not fully known, but it has been demonstrated that both left-right and anterior-posterior asymmetry is required for intestinal twist to occur. We have recently presented a rule-based meta-Boolean tree model intended to describe complex lineages. In this report we apply this model to the E lineage of C. elegans, specifically targeting the asymmetric anterior-posterior division patterns within the lineage. The resulting model indicates that cells with the same factor concentration are located next to each other in the intestine regardless of lineage origin. In addition, the shift in factor concentrations coincides with the boundary for intestinal twist. When modeling lit-1 mutant data according to the same principle, the factor distributions in each cell are altered, yet the concurrence between the shift in concentration and intestinal twist remains. This pattern suggests that intestinal twist is controlled by a threshold mechanism. In the current paper we present the factor concentrations for all possible combinations of symmetric and asymmetric divisions in the E lineage and relate these to the potential threshold by studying existing data for wild-type and mutant embryos. Finally, we discuss how the resulting models can serve as a basis for experimental design in order to reveal the underlying mechanisms of intestinal twist.

  • 47.
    Setterqvist, Eric
    et al.
    Linköping University, Department of Mathematics, Mathematics and Applied Mathematics. Linköping University, Faculty of Science & Engineering. Univ Vienna, Austria.
    Forchheimer, Robert
    Linköping University, Department of Electrical Engineering, Information Coding. Linköping University, Faculty of Science & Engineering.
    Real-Time Communication Systems based on Taut Strings2018In: Journal of Communications and Networks, ISSN 1229-2370, E-ISSN 1976-5541, Vol. 20, no 2, p. 207-218Article in journal (Refereed)
    Abstract [en]

    We consider buffered real-time communication over channels with time-dependent capacities which are known in advance. The real-time constraint is imposed in terms of limited transmission time between sender and receiver. For a network consisting of a single channel it is shown that there is a coding rate strategy, geometrically characterized as a taut string, which minimizes the average distortion with respect to all convex distortionrate functions. Utilizing the taut string characterization further, an algorithm that computes the optimal coding rate strategy is provided. We then consider more general networks with several connected channels in parallel or series with intermediate buffers. It is shown that also for these networks there is a coding rate strategy, geometrically characterized as a taut string, which minimizes the average distortion with respect to all convex distortion-rate functions. The optimal offline strategy provides a benchmark for the evaluation of different coding rate strategies. Further, it guides us in the construction of a simple but rather efficient strategy for channels in the online setting which alternates between a good and a bad state.

  • 48.
    Svensson, Per-Olof
    et al.
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Nilsson, David
    Acreo AB.
    Forchheimer, Robert
    Linköping University, Department of Electrical Engineering. Linköping University, The Institute of Technology.
    Berggren , Magnus
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    A sensor circuit using reference-based conductance switching in organic electrochemical transistors2008In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 93, no 20, p. 203301-Article in journal (Refereed)
    Abstract [en]

    Using organic electrochemical transistors as sensors, the sample-receptor reaction often induces moderate changes only in the drain current dynamics as the gate voltage level is switched. Here, we report an electrochemical sensor circuit including electrochemical transistors based on poly(3,4-ethylenedioxythiophene) doped with polystyrenesulfonate that puts out a static sensor response signal. The circuit includes a sample and a reference transistor that are both driven in the resistive mode at 0.1 V. Measurements were performed on aqueous salt electrolytes ranging from 100 to 500 mM concentrations. The signal-ON sensor circuit provides a tenfold increase in the sensitivity as compared to single transistor sensors.

  • 49.
    Toss, Henrik
    et al.
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, Faculty of Science & Engineering.
    Sani, Negar
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, Faculty of Science & Engineering.
    Fabiano, Simone
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, Faculty of Science & Engineering.
    Simon, Daniel T
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, Faculty of Science & Engineering.
    Forchheimer, Robert
    Linköping University, Department of Electrical Engineering, Information Coding. Linköping University, Faculty of Science & Engineering.
    Berggren, Magnus
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, Faculty of Science & Engineering.
    Polarization of ferroelectric films through electrolyte2016In: Journal of Physics: Condensed Matter, ISSN 0953-8984, E-ISSN 1361-648X, Vol. 28, no 10, article id 105901Article in journal (Refereed)
    Abstract [en]

    A simplified model is developed to understand the field and potential distribution through devices based on a ferroelectric film in direct contact with an electrolyte. Devices based on the ferroelectric polymer polyvinylidenefluoride-trifluoroethylene (PVDF-TrFE) were produced – in metalferroelectric-metal, metal-ferroelectric-dielectric-metal, and metal-ferroelectric-electrolyte-metal architectures – and used to test the model, and simulations based on the model and these fabricated devices were performed. From these simulations we find indication of progressive polarization of the films. Furthermore, the model implies that there is a relation between the separation of charge within the devices and the observed open circuit voltage. This relation is confirmed experimentally. The ability to polarize ferroelectric polymer films through aqueous electrolytes, combined with the strong correlation between the properties of the electrolyte double layer and the device potential, opens the door to a variety of new applications for ferroelectric technologies, e.g., regulation of cell culture growth and release, steering molecular self-assembly, or other large area applications requiring aqueous environments.

  • 50.
    Tu, Deyu
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Electrical Engineering, Information Coding.
    Forchheimer, Robert
    Linköping University, The Institute of Technology. Linköping University, Department of Electrical Engineering, Information Coding.
    Self-oscillation in electrochemical transistors: An RLC modeling approach2012In: Solid-State Electronics, ISSN 0038-1101, E-ISSN 1879-2405, Solid-State Electronics: an international journal, ISSN 0038-1101, Vol. 69, p. 7-10Article in journal (Refereed)
    Abstract [en]

    We propose an RLC model for PEDOT:PSS electrochemical transistors to interpret the persistent oscillating currents observed in experiments. The electrochemical reaction is represented by an inductor in the equivalent circuit. The simulation results show that an electrochemical device can be operated as normal transistors or oscillators under different voltage bias. This model predicts that analog circuit functions can be realized with "inductor-like" electrochemical devices.

12 1 - 50 of 56
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