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  • 301.
    Kleyko, Denis
    et al.
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Datavetenskap.
    Lyamin, Nikita
    Halmstad University.
    Osipov, Evgeny
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Datavetenskap.
    Modified algorithm of dynamic frequency hopping (DFH) in the IEEE 802.22 standard2014Ingår i: Multiple Access Communications: 7th International Workshop, MACOM 2014, Halmstad, Sweden, August 27-28, 2014. Proceedings / [ed] Magnus Jonsson; Alexey Vinel; Boris Bellalta; Evgeny Belyaev, New York: Encyclopedia of Global Archaeology/Springer Verlag, 2014, s. 75-83Konferensbidrag (Refereegranskat)
    Abstract [en]

    IEEE 802.22 Cognitive Wireless Regional Area Networks is a first standard of wireless terrestrial system relying on cognitive radio concept and operating as an opportunistic system in the the vacant unoccupied frequency spaces of the licensed TV-frequency band. Concept of the proposed standard assumes special functionality to protect the operation of the primary licensed subscribers. Dynamic Frequency Hopping is the mechanism for providing connectionless operation of Wireless Regional Area Networks systems while ensuring protection of transmissions from the primary users. During its operation regular time gaps appear on the involved frequency channels. This paper introduces the concept of the efficient reuse of the vacant frequency resources appearing when using the Dynamic Frequency Hopping mode. The scheme for consecutive-parallel inclusion of the new Dynamic Frequency Hopping Communities-members in the Dynamic Frequency Hopping mode is presented. The proposed approach allows to significantly decrease transition time.

  • 302.
    Kleyko, Denis
    et al.
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Datavetenskap.
    Lyamin, Nikita
    Siberian State University of Telecommunications and Information Sciences.
    Osipov, Evgeny
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Datavetenskap.
    Riliskis, Laurynas
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Datavetenskap.
    Dependable MAC layer architecture based on holographic data representation using hyper-dimensional binary spatter codes2012Ingår i: Multiple Access Communications: 5th International Workshop, MACOM 2012, Maynooth, Ireland, November 19-20, 2012. Proceedings / [ed] Boris Bellalta, Heidelberg: Encyclopedia of Global Archaeology/Springer Verlag, 2012, s. 134-145Konferensbidrag (Refereegranskat)
    Abstract [en]

    In this article we propose the usage of binary spatter codes and distributed data representation for communicating loss and delay sensitive data in event-driven sensor and actuator networks. Using the proposed data representation technique along with the medium access control protocol the mission critical control information can be transmitted with assured constant delay in deployments exposing below 0 dB signal-to-noise ratio figures.

  • 303.
    Kleyko, Denis
    et al.
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Datavetenskap.
    Osipov, Evgeny
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Datavetenskap.
    Brain-like classifier of temporal patterns2014Ingår i: International Conference on Computer and Information Sciences, ICCOINS 2014, Kuala Lumpur, Malaysia, June 03-05, 2014. Proceedings, Piscataway, NJ: IEEE Communications Society, 2014, s. 1-6Konferensbidrag (Refereegranskat)
    Abstract [en]

    In this article we present a pattern classification system which uses Vector Symbolic Architecture (VSA) for representation, learning and subsequent classification of patterns, as a showcase we have used classification of vibration sensors measurements to vehicles types. On the quantitative side the proposed classifier requires only 1 kB of memory to classify an incoming signal against of several hundred of training samples. The classification operation into N types requires only 2*N+1 arithmetic operations this makes the proposed classifier feasible for implementation on a low-end sensor nodes. The main contribution of this article is the proposed methodology for representing temporal patterns with distributed representation and VSA-based classifier.

  • 304.
    Kleyko, Denis
    et al.
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Datavetenskap.
    Osipov, Evgeny
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Datavetenskap.
    No Two Brains Are Alike: Cloning a Hyperdimensional Associative Memory Using Cellular Automata Computations2017Ingår i: Biologically Inspired Cognitive Architectures (BICA) for Young Scientists: First International Early Research Career Enhancement School on BICA and Cybersecurity (FIERCES 2017) / [ed] Alexei V. Samsonovich, Valentin V. Klimov, Cham: Springer, 2017, s. 91-100Konferensbidrag (Refereegranskat)
    Abstract [en]

    This paper looks beyond of the current focus of research on biologically inspired cognitive systems and considers the problem of replication of its learned functionality. The considered challenge is to replicate the learned knowledge such that uniqueness of the internal symbolic representations is guaranteed. This article takes a neurological argument “no two brains are alike” and suggests an architecture for mapping a content of the trained associative memory built using principles of hyperdimensional computing and Vector Symbolic Architectures into a new and orthogonal basis of atomic symbols. This is done with the help of computations on cellular automata. The results of this article open a way towards a secure usage of cognitive architectures in a variety of practical application domains.

  • 305.
    Kleyko, Denis
    et al.
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Datavetenskap.
    Osipov, Evgeny
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Datavetenskap.
    On bidirectional transitions between localist and distributed representations: The case of common substrings search using Vector Symbolic Architecture2014Ingår i: Procedia Computer Science, ISSN 1877-0509, E-ISSN 1877-0509, Vol. 41, s. 104-113Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The contribution of this article is twofold. First, it presents an encoding approach for seamless bidirectional transitions between localist and distributed representation domains. Second, the approach is demonstrated on the example of using Vector Symbolic Architecture for solving a problem of finding common substrings. The proposed algorithm uses elementary operations on long binary vectors. For the case of two patterns with respective lengths L1 and L2 it requires Θ(L1 + L2 – 1) operations on binary vectors, which is equal to the suffix trees approach – the fastest algorithm for this problem. The simulation results show that in order to be robustly detected by the proposed approach the length of a common substring should be more than 4% of the longest pattern.

  • 306.
    Kleyko, Denis
    et al.
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Datavetenskap.
    Osipov, Evgeny
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Datavetenskap.
    Björk, Magnus
    Luleå tekniska universitet.
    Toresson, Henrik
    Luleå tekniska universitet.
    Öberg, Anton
    Luleå tekniska universitet.
    Fly-The-Bee: A game imitating concept learning in bees2015Ingår i: Procedia Computer Science, ISSN 1877-0509, E-ISSN 1877-0509, Vol. 71, s. 25-30Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    This article presents a web-based game functionally imitating a part of the cognitive behavior of a living organism. This game is a prototype implementation of an artificial online cognitive architecture based on the usage of distributed data representations and Vector Symbolic Architectures. The game emonstrates the feasibility of creating a lightweight cognitive architecture, which is capable of performing rather complex cognitive tasks. The cognitive functionality is implemented in about 100 lines of code and requires few tens of kilobytes of memory for its operation, which make the concept suitable for implementing in low-end devices such as minirobots and wireless sensors.

  • 307.
    Kleyko, Denis
    et al.
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Datavetenskap.
    Osipov, Evgeny
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Datavetenskap.
    Gayler, Ross W.
    La Trobe University.
    Recognizing permuted words with Vector Symbolic Architectures: A Cambridge test for machines2016Ingår i: Procedia Computer Science, ISSN 1877-0509, E-ISSN 1877-0509, Vol. 88, s. 169-175Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    This paper proposes a simple encoding scheme for words using principles of Vector Symbolic Architectures. The proposed encoding allows finding a valid word in the dictionary for a given permuted word (represented using the proposed approach) using only a single operation - calculation of Hamming distance to the distributed representations of valid words in the dictionary. The proposed encoding scheme can be used as an additional processing mechanism for models of word embedding, which also form vectors to represent the meanings of words, in order to match the distorted words in the text to the valid words in the dictionary.

  • 308.
    Kleyko, Denis
    et al.
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Datavetenskap.
    Osipov, Evgeny
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Datavetenskap.
    Gayler, Ross W.
    La Trobe University.
    Khan, Asad I.
    Monash University, Melbourne, VIC, Clayton School of Information Technology, CSIT, Monash University.
    Dyer, Adrian G.
    Media and Communication School, Royal Melbourne Institute of Technology.
    Imitation of honey bees’ concept learning processes using Vector Symbolic Architectures2015Ingår i: Biologically Inspired Cognitive Architectures, ISSN 2212-683X, E-ISSN 2212-6848, Vol. 14, s. 57-72Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    This article presents a proof-of-concept validation of the use of Vector Symbolic Architectures as central component of an online learning architectures. It is demonstrated that Vector Symbolic Architectures enable the structured combination of features/relations that have been detected by a perceptual circuitry and allow such relations to be applied to novel structures without requiring the massive training needed for classical neural networks that depend on trainable connections.The system is showcased through the functional imitation of concept learning in honey bees. Data from real-world experiments with honey bees (Avarguès-Weber et al., 2012) are used for benchmarking. It is demonstrated that the proposed pipeline features a similar learning curve and accuracy of generalization to that observed for the living bees. The main claim of this article is that there is a class of simple artificial systems that reproduce the learning behaviors of certain living organisms without requiring the implementation of computationally intensive cognitive architectures. Consequently, it is possible in some cases to implement rather advanced cognitive behavior using simple techniques.

  • 309.
    Kleyko, Denis
    et al.
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Datavetenskap.
    Osipov, Evgeny
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Datavetenskap.
    Papakonstantinou, Nikolaos
    VTT Technical Research Center of Finland.
    Vyatkin, Valeriy
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Datavetenskap. Department of Electrical Engineering and Automation, Aalto University, Finland.
    Hyperdimensional computing in industrial systems: the use-case of distributed fault isolation in a power plant2018Ingår i: IEEE Access, E-ISSN 2169-3536, Vol. 6, s. 30766-30777Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    This paper presents an approach for distributed fault isolation in a generic system of systems. The proposed approach is based on the principles of hyperdimensional computing. In particular, the recently proposed method called Holographic Graph Neuron is used. We present a distributed version of Holographic Graph Neuron and evaluate its performance on the problem of fault isolation in a complex power plant model. Compared to conventional machine learning methods applied in the context of the same scenario the proposed approach shows comparable performance while being distributed and requiring simple binary operations, which allow for a fast and efficient implementation in hardware.

  • 310.
    Kleyko, Denis
    et al.
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Datavetenskap.
    Osipov, Evgeny
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Datavetenskap.
    Papakonstantinou, Nikolaos
    VTT Technical Research Centre of Finland, Espoo.
    Vyatkin, Valeriy
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Datavetenskap.
    Mousavi, Arash
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Datavetenskap.
    Fault Detection in the Hyperspace: Towards Intelligent Automation Systems2015Ingår i: IEEE International Conference on Industrial Informatics: INDIN 2015, Cambridge, UK, July 22-24, 2015. Proceedings, Piscataway, NJ: IEEE Communications Society, 2015, s. 1219-1224, artikel-id 7281909Konferensbidrag (Refereegranskat)
    Abstract [en]

    This article presents a methodology for intelligent, biologically inspired fault detection system for generic complex systems of systems. The proposed methodology utilizes the concepts of associative memory and vector symbolic architectures, commonly used for modeling cognitive abilities of human brain. Compared to classical methods of artificial intelligence used in the context of fault detection the proposed methodology shows an unprecedented performance, while featuring zero configuration and simple operations.

  • 311.
    Kleyko, Denis
    et al.
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Datavetenskap.
    Osipov, Evgeny
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Datavetenskap.
    Patil, Sandeep
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Datavetenskap.
    Vyatkin, Valeriy
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Datavetenskap.
    Pang, Zhibo
    ABB AB, Corporate research.
    On Methodology of Implementing Distributed Function Block Applications using TinyOS WSN nodes2014Ingår i: Proceedings of 2014 IEEE 19th International Conference on Emerging Technologies & Factory Automation (ETFA 2014): Barcelona, Spain, 16-19 Sept. 2014, Piscataway, NJ: IEEE Communications Society, 2014, artikel-id 7005107Konferensbidrag (Refereegranskat)
    Abstract [en]

    This paper presents a feasibility study of implementing parts of a distributed function block application as TinyOS modules running on Wireless Sensors as a part of Wireless Sensor Network. The paper first briefly describes underlying technologies and gives motivation for implementation of function blocks in TinyOS. The paper then presents implementation details about TinyOS realization of the one of the function block, which is a part of bigger distributed control application with the help of distributed function block application.

  • 312.
    Kleyko, Denis
    et al.
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Datavetenskap.
    Osipov, Evgeny
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Datavetenskap.
    Rachkovskij, Dmitri A.
    International Research and Training Center for Information Technologies and Systems.
    Modification of Holographic Graph Neuron using Sparse Distributed Representations2016Ingår i: Procedia Computer Science, ISSN 1877-0509, E-ISSN 1877-0509, Vol. 88, s. 39-45Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    This article presents a modification of the recently proposed Holographic Graph Neuron approach for memorizing patterns of generic sensor stimuli. The original approach represents patterns as dense binary vectors, where zeros and ones are equiprobable. The presented modification employs sparse binary distributed representations where the number of ones is less than zeros. Sparse representations are more biologically plausible because activities of real neuronsare sparse. Performance was studied comparing approaches for different sizes of dimensionality.

  • 313.
    Kleyko, Denis
    et al.
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Datavetenskap.
    Osipov, Evgeny
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Datavetenskap.
    Senior, Alexander
    Monash University, Melbourne, VIC.
    Khan, Asad
    Monash University, Melbourne, VIC.
    Sekercioglu, Ahmet
    Monash University, Melbourne, VIC.
    Holographic Graph Neuron: a Bio-Inspired Architecture for Pattern Processing2017Ingår i: IEEE Transactions on Neural Networks and Learning Systems, ISSN 2162-237X, E-ISSN 2162-2388, Vol. 28, nr 6, s. 1250-1262Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    This article proposes the use of Vector Symbolic Architectures for implementing Hierarchical Graph Neuron, an architecture for memorizing patterns of generic sensor stimuli. The adoption of a Vector Symbolic representation ensures a one-layered design for the approach, while maintaining the previously reported properties and performance characteristics of Hierarchical Graph Neuron, and also improving the noise resistance of the architecture. The proposed architecture enables a linear (with respect to the number of stored entries) time search for an arbitrary sub-pattern.

  • 314.
    Kleyko, Denis
    et al.
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Datavetenskap.
    Osipov, Evgeny
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Datavetenskap.
    Wiklund, Urban
    Department of Radiation Sciences, Biomedical Engineering, Umeå University, Umeå, Sweden.
    A Hyperdimensional Computing Framework for Analysis of Cardiorespiratory Synchronization during Paced Deep Breathing2019Ingår i: IEEE Access, E-ISSN 2169-3536, Vol. 7, s. 34403-34415Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Objective: Autonomic function during deep breathing (DB) is normally scored based on the assumption that the heart rate is synchronized with the breathing. We have observed individuals with subtle arrhythmias during DB where autonomic function cannot be evaluated. This study presents a novel method for analyzing cardiorespiratory synchronization: feature-based analysis of the similarity between heart rate and respiration using principles of hyperdimensional computing. Methods: Heart rate and respiration signals were modeled using Fourier series analysis. Three feature variables were derived and mapped to binary vectors in a high-dimensional space. Using both synthesized data and recordings from patients/healthy subjects, the similarity between the feature vectors was assessed using Hamming distance (high-dimensional space), Euclidean distance (original space), and with a coherence-based index. Methods were evaluated via classification of the similarity indices into three groups. Results: The distance-based methods achieved good separation of signals into classes with different degree of cardiorespiratory synchronization, also providing identification of patients with low cardiorespiratory synchronization but high values of conventional DB scores. Moreover, binary high-dimensional vectors allowed an additional analysis of the obtained Hamming distance. Conclusions: Feature-based similarity analysis using hyperdimensional computing is capable of identifying signals with low cardiorespiratory synchronization during DB due to arrhythmias. Vector-based similarity analysis could be applied to other types of feature variables than based on spectral analysis. Significance: The proposed methods for robustly assessing cardiorespiratory synchronization during DB facilitate the identification of individuals where the evaluation of autonomic function is problematic or even impossible, thus, increasing the correctness of the conventional DB scores.

  • 315.
    Kleyko, Denis
    et al.
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Datavetenskap.
    Rahimi, Abbas
    ETH Zurich, Zurich, Switzerland.
    Gayler, Ross W.
    Melbourne, Australia.
    Osipov, Evgeny
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Datavetenskap.
    Autoscaling Bloom filter: Controlling trade-off between true and false positives2019Ingår i: Neural computing & applications (Print), ISSN 0941-0643, E-ISSN 1433-3058Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A Bloom filter is a special case of an artificial neural network with two layers. Traditionally, it is seen as a simple data structure supporting membership queries on a set. The standard Bloom filter does not support the delete operation, and therefore, many applications use a counting Bloom filter to enable deletion. This paper proposes a generalization of the counting Bloom filter approach, called “autoscaling Bloom filters”, which allows adjustment of its capacity with probabilistic bounds on false positives and true positives. Thus, by relaxing the requirement on perfect true positive rate, the proposed autoscaling Bloom filter addresses the major difficulty of Bloom filters with respect to their scalability. In essence, the autoscaling Bloom filter is a binarized counting Bloom filter with an adjustable binarization threshold. We present the mathematical analysis of its performance and provide a procedure for minimizing its false positive rate.

  • 316.
    Kljun, Matjaz
    et al.
    University of Primorska.
    Carr, David
    Luleå tekniska universitet.
    Piles of thumbnails: visualizing document management2005Ingår i: Information Technology Interfaces / [ed] Vesna Lužar-Stiffler, Zabreb: SRCE University Computing Centre, Univ. of Zagreb, , 2005, s. 273-278Konferensbidrag (Refereegranskat)
    Abstract [en]

    Digital information is present in everyone's life. Most of the time we spend in front of a computer is in managing (processing, creating, editing, searching, and organizing), digital documents. Current tools for managing digital information are based on concepts developed over 40 years ago. Even with the desktop metaphor and improved visualization, these methods do not support management of large amounts of information. This paper provides an overview of the current state of personal information management and suggests a design based on a "piles of documents" metaphor that more closely supports the working habits of many users.

  • 317.
    Klockar, Tomas
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Datavetenskap.
    Improving routing in the global Internet2005Licentiatavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    Routing is an important part of the Internet and even though routing in the Internet has been investigated since Internet's creation, there are still open issues. Routing protocols have been evolved since the birth of Internet. Currently the Border Gateway Protocol(BGP) is the de-facto standard inter domain routing protocol on the Internet. In 1990 came the first version of BGP which has evolved to todays BGP-4 through several versions and extensions. The capability has increased for every new version and extension, but so has the complexity. This makes it harder to get an overview of how routers behave. In many cases the global view of the routing within the Autonomous System (AS) is missing. When the global view is missing, it is difficult for routers to chose a stable route and in some cases it is impossible. Oscillation is one of the larger problems and for I-BGP several solutions have been suggested. We present a new algorithm that prevents intra AS oscillation. The basic idea is to store routes that are not explicitly removed because those routes can still be used, although they are currently not active. This way the selection algorithm has a larger set of routes to choose from when it selects the best route. Routes that are not currently used can not be selected but can be used to remove others from the allowed set. BGP can also be improved by adjusting it to a new decentralized router architecture and at the same time solving several intra AS problems. We have been investigating this problem and suggested a modularization of BGP. The modularization is designed to fit on top of the Forward Element and Control Element separation of the router. The forwarding table and session manager have been separated from the decision process and Routing Information Bases(RIB). The solution is very flexible and allows that the router is built with redundancy and still keeps the cost down. We also present algorithms for calculating the k shortest paths in a distributed manner. This algorithm has its roots in BGP. It runs in waves to compute the k shortest paths. The algorithm produces paths that can be used for routing to solve load-balancing problems or as backup paths.

  • 318. Klockar, Tomas
    et al.
    Carr, David A.
    Luleå tekniska universitet.
    Hedman, Anna
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Signaler och system.
    Johansson, Tomas
    Bengtsson, Fredrik
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Datavetenskap.
    Usability of mobile phones2003Ingår i: Proceedings of the 19th International Symposium on Human Factors in Telecommunications, 2003, s. 197-204Konferensbidrag (Refereegranskat)
  • 319. Klockar, Tomas
    et al.
    Carr-Motyckova, Lenka
    Preventing oscillations in route reflector-based I-BGP2004Ingår i: Proceedings: 13th International Conference on Computer Communications and Networks, ICCCN 2004, 11 - 13 October 2004, Holiday Inn Chicago - O'Hare Intl, Chicago, IL, USA / [ed] Luiz DaSilva, Piscataway, NJ: IEEE Communications Society, 2004, s. 53-58Konferensbidrag (Refereegranskat)
    Abstract [en]

    We present a modification to the internal border gateway protocol that prevents oscillation. We deal with oscillations caused by multi-exit-discriminators within a single autonomous system. The algorithm keeps track of all valid routes it has received. Then the best route is chosen from the set of valid routes. There is no need for extra messages as compared to the standard internal border gateway protocol. As long as there is just one route to a destination, the algorithm stays dormant and the properties of the standard internal border gateway protocol are preserved.

  • 320.
    Kollnitz, Gunnar
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Datavetenskap.
    Implementation of Network Components for Game Projects2018Självständigt arbete på avancerad nivå (yrkesexamen), 10 poäng / 15 hpStudentuppsats (Examensarbete)
    Abstract [sv]

    I majoriteten av datorspel som släpps nuförtiden, är flerspelar gameplay ett av de största fokusen, och i kärnan av den funktionen finns nätverkskoden. Detta betyder att dålig nätverkskod kan förstöra upplevelsen helt och hållet. A Sweet Studio är en mindre spelstudio som både gör konsultarbete inom industrin, och utvecklar sina egna spel. Men med begränsad tid och begränsade pengar att spendera på sina egna projekt, kan det bli tufft att skapa nya spel. Mening med den här rapporten är att gå över hur en flerspelarbas kan utvecklas i Unity, itereras över och hur den bäst byggs för återanvändning, så att det lätt går att implementeras i nya projekt. Slutresultatet är ett bibliotek med bred funktionalitet och en simpel layout.

  • 321.
    Kolsch, A.
    et al.
    MindGarage, University of Kaiserslautern, Germany; Insiders Technologies GmbH, Kaiserslautern, Germany.
    Mishra, A.
    MindGarage, University of Kaiserslautern, Germany.
    Varshneya, S.
    MindGarage, University of Kaiserslautern, Germany; Insiders Technologies GmbH, Kaiserslautern, Germany.
    Afzal, M.Z
    MindGarage, University of Kaiserslautern, Germany; Insiders Technologies GmbH, Kaiserslautern, Germany.
    Liwicki, Marcus
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, EISLAB. MindGarage, University of Kaiserslautern, Germany; Insiders Technologies GmbH, Kaiserslautern, Germany; University of Fribourg, Switzerland.
    Recognizing challenging handwritten annotations with fully convolutional networks2018Ingår i: Proceedings of International Conference on Frontiers in Handwriting Recognition, ICFHR 2018, IEEE, 2018, s. 25-31, artikel-id 8563221Konferensbidrag (Refereegranskat)
    Abstract [en]

    This paper introduces a very challenging dataset of historic German documents and evaluates Fully Convolutional Neural Network (FCNN) based methods to locate handwritten annotations of any kind in these documents. The handwritten annotations can appear in form of underlines and text by using various writing instruments, e.g., the use of pencils makes the data more challenging. We train and evaluate various end-to-end semantic segmentation approaches and report the results. The task is to classify the pixels of documents into two classes: Background and handwritten annotation. The best model achieves a mean Intersection over Union (IOU) score of 95.6% on the test documents of the presented dataset. We also present a comparison of different strategies used for data augmentation and training on our presented dataset. For evaluation, we use the Layout Analysis Evaluator for the ICDAR 2017 Competition on Layout Analysis for Challenging Medieval Manuscripts.

  • 322.
    Kor, Ah-Lian
    et al.
    Leeds Beckett University.
    Rondeau, Eric
    University of Lorraine, Nancy, France.
    Andersson, Karl
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Datavetenskap.
    Porras, Jari
    Lappeenranta University of Technology, Finland.
    Georges, Jean-Philippe
    University of Lorraine, Nance, France.
    Education in Green ICT and Control of Smart Systems: A First Hand Experience from the International PERCCOM Masters Programme2019Ingår i: Proceedings of the 12th International Federation of Automatic Control Symposium on Advances in Control Education (IFAC-ACE 2019), 2019, Vol. 52, s. 1-8, artikel-id 9Konferensbidrag (Refereegranskat)
    Abstract [en]

    PERCCOM (PERvasive Computing and COMmunications in sustainable development) Masters is the first innovative international programme in Green ICT for educating and equipping new IT engineers with Green IT skills for sustainable digital applications design and implementation. After five years of running the PERCCOM programme, this paper provides an assessment of skills and employability in the context of Green jobs and skills. The paper ends with a list of recommendations for the development of environment related education curricula.

  • 323.
    Krasheninnikov, Pavel V.
    et al.
    Siberian State University of Telecommunications and Information Sciences, Novosibirsk, Russia.
    Melent’ev, Oleg G.
    Siberian State University of Telecommunications and Information Sciences, Novosibirsk, Russia.
    Kleyko, Denis
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Datavetenskap.
    Shapin, Alexey
    Ericsson Research, Luleå, Sweden.
    Parameter Estimation for the Resulting Logical Channel Formed by Minimizing Channel Switching2019Ingår i: Automation and remote control, ISSN 0005-1179, E-ISSN 1608-3032, Vol. 80, nr 2, s. 278-285Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We propose a method for calculating the parameters of the resulting discrete channel for secondary users in cognitive radio systems formed by the algorithm for minimizing channel switchings. The availability of channel slots is defined by a simple Markov chain. We obtain mathematical expressions for determining the transition probabilities of a graph reduced to two states for any number of primary channels.

  • 324.
    Kunz, Guilherme
    et al.
    Mechanical Engineering Department, Western Parana State University, Foz do Iguazu, Brazil.
    Machado, José
    Mechanical Engineering Department and MEtRICs Research Centre, University of Minho, Guimaraes, Portugal.
    Perondi, Eduardo
    Mechanical Engineering Department, Federal University of Rio Grande do Sul, Porto Alegre, Brazil.
    Vyatkin, Valeriy
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Datavetenskap.
    A Formal Methodology for Accomplishing IEC61850 Real-Time Communication Requirements2017Ingår i: IEEE transactions on industrial electronics (1982. Print), ISSN 0278-0046, E-ISSN 1557-9948, Vol. 64, nr 8, s. 6582-6590, artikel-id 7878522Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Reliability is extremely important for control systems of energy distribution and generation. The IEC 61850 standard specifies an open architecture and communication protocols for such applications. The standard defines an open control architecture for networked control systems composed by intelligent electronic devices, stating some requirements that must be accomplished when developing reliable controllers for such systems. In this work, we present a systematic and formal methodology to be adopted to achieve the correct implementation of the communication requirements of this standard. The methodology consists in five steps: modeling of real-time communication requirements defined by the standard; simulation of the obtained model; formal verification of the model, improved in the previous step; translation of the global model (simulated and verified) into the input language of the real controller; and, finally, application of conformance testing technique to the computational routine implemented in the real controller. Presented research deals with the proposition of a strategy to synthesize and validate models of systems developed under IEC61850 real-time requirements (GOOSE and SMV) through simple operational conditions cases that, once validated, can be used in performance and conformance testing of more complex systems. The proposed methodology allows designers to synthesize reliable systems under IEC61850 real-time communication requirements.

  • 325.
    Laato, Samuli
    et al.
    University of Turku.
    Pietarinen, Tarja
    University of Turku.
    Rauti, Sampsa
    University of Turku.
    Laine, Teemu
    Luleå tekniska universitet, Institutionen för system- och rymdteknik.
    Analysis of the Quality of Points of Interests in the Most Popular Location-based Games2019Konferensbidrag (Refereegranskat)
  • 326.
    Laine, Teemu H.
    et al.
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Datavetenskap.
    Suk, Haejung
    Ajou University.
    Designing Educational Mobile Augmented Reality Games Using Motivators and Disturbance Factors2019Ingår i: Augmented Reality Games II: The Gamification of Education, Medicine and Art / [ed] Vladimir Geroimenko, Springer, 2019, s. 33-56Kapitel i bok, del av antologi (Refereegranskat)
    Abstract [en]

    This is the second of two comprehensive volumes that provide a thorough and multi-faceted research into the emerging field of augmented reality games and consider a wide range of its major issues. These first ever research monographs on augmented reality games have been written by a team of 70 leading researchers, practitioners and artists from 20 countries. 

    Volume II explores the most important and challenging issues that have been raised by the use of the Augmented Reality approach and technology in the gamification of education, healthcare, medicine and art. The volume deals with a systematic analysis of educational augmented reality games, their use for health promotion in old age and for improving people’s well-being, the gamification of augmented reality art and immersive reading experiences, among other topics.

  • 327.
    Landström, Anders
    et al.
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Signaler och system.
    Nellros, Frida
    Luleå tekniska universitet, Institutionen för system- och rymdteknik.
    Jonsson, Håkan
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Datavetenskap.
    Thurley, Matthew
    Image reconstruction by prioritized incremental normalized convolution2011Ingår i: Image analysis: 17th Scandinavian conference, SCIA 2011, Ystad, Sweden, May 2011 ; proceedings / [ed] Anders Heyden; Fredrik Kahl, Berlin: Encyclopedia of Global Archaeology/Springer Verlag, 2011, s. 176-185Konferensbidrag (Refereegranskat)
    Abstract [en]

    A priority-based method for pixel reconstruction and incrementalhole filling in incomplete images and 3D surface data is presented.The method is primarily intended for reconstruction of occluded areasin 3D surfaces and makes use of a novel prioritizing scheme, based on apixelwise defined confidence measure, that determines the order in whichpixels are iteratively reconstructed. The actual reconstruction of individualpixels is performed by interpolation using normalized convolution.The presented approach has been applied to the problem of reconstructing3D surface data of a rock pile as well as randomly sampled imagedata. It is concluded that the method is not optimal in the latter case,but the results show an improvement to ordinary normalized convolutionwhen applied to the rock data and are in this case comparable to thoseobtained from normalized convolution using adaptive neighborhood sizes.

  • 328.
    Landström, Anders
    et al.
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Signaler och system.
    Simonsson, Arne
    Ericsson Research, Luleå.
    Jonsson, Håkan
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Datavetenskap.
    Voronoi-based ISD and site density characteristics for mobile networks2012Ingår i: 2012 IEEE 76th Vehicular Technology Conference: VTC2012-Fall: Towards Sustainable Mobility; Proceedings, Piscataway, NJ: IEEE Communications Society, 2012Konferensbidrag (Refereegranskat)
    Abstract [en]

    Inter-Site Distance (ISD) is a common measure for characterizing the site density in a mobile network However, obtaining a good estimation of the ISD for a real world network is not trivial since the physical layout is usually quite more complex than a perfect theoretical hexagonal grid, due to a number of unavoidable factors such as site availability and traffic density. Voronoi diagrams have been suggested for approximating cells from network layouts, providing a method for partitioning the covered area into cells defined by the proximity to the given set of sites. This yields a framework for site coverage approximation based on the actual site distribution, rather than an underlying theoretical model.We present a novel measure, based on Voronoi diagrams, for characterizing the site density of a cellular network and provide a comparison to the more traditional ISD measure. This measure improves capacity assessments and modeling of real networks.

  • 329.
    Landström, Anders
    et al.
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Signaler och system.
    Thurley, Matthew
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Signaler och system.
    Jonsson, Håkan
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Datavetenskap.
    Adaptive Morphological Filtering of Incomplete Data2014Ingår i: 2013 International Conference on Digital Image Computing: Techniques and Applications (DICTA 2013): Hobart, Australia, 26-28 Nov. 2013, Piscataway, NJ: IEEE Communications Society, 2014, artikel-id 6691479Konferensbidrag (Refereegranskat)
    Abstract [en]

    We demonstrate how known convolution techniques for uncertain data can be used to set the shapes of structuring elements in adaptive mathematical morphology, enabling robust morphological processing of partially occluded or otherwise incomplete data. Results are presented for filtering of both gray-scale images containing missing data and 3D profile data where information is missing due to occlusion effects. The latter demonstrates the intended use of the method: enhancement of crack signatures in a surface inspection system for casted steel.The presented method is able to disregard unreliable data in a systematic and robust way, enabling adaptive morphological processing of the available information while avoiding any false edges or other unwanted features introduced by the values of faulty pixels.

  • 330.
    Landström, Anders
    et al.
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Signaler och system.
    Thurley, Matthew
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Signaler och system.
    Jonsson, Håkan
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Datavetenskap.
    Sub-millimeter crack detection in casted steel using color photometric stereo2014Ingår i: 2013 International Conference on Digital Image Computing Techniques and Applications (DICTA 2013: Hobart, Australia, 26-28 November 2013, Piscataway, NJ: IEEE Communications Society, 2014, artikel-id 6691532Konferensbidrag (Refereegranskat)
    Abstract [en]

    A novel method for automated inspection of small corner cracks in casted steel is presented, using a photometric stereo setup consisting of two light sources of different colors in conjunction with a line-scan camera. The resulting image is separated into two different reflection patterns which are used to cancel shadow effects and estimate the surface gradient. Statistical methods are used to first segment the image and then provide an estimated crack probability for each segmented region. Results show that true cracks are successfully assigned a high crack probability, while only a minor proportion of other regions cause similar probability values. About 80% of the cracks present in the segmented regions are given a crack probability higher than 70%, while the corresponding number for other non-crack regions is only 5%. The segmented regions contain over 70% of the manually identified crack pixels. We thereby provide proof-of-concept for the presented method.

  • 331.
    Landström, Sara
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Datavetenskap.
    TCP/IP technology for modern network environments2008Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    To facilitate the merging of wireless access technologies and the traditional Internet, the core protocols for data communication should be robust and have low overhead. In this thesis, we propose refinements to the Transmission Control Protocol (TCP) that improve its cost efficiency over wireless links.TCP is unable to distinguish between congestion and error induced losses, reordered, or delayed segments. A reordering robust TCP would make it possible to simplify network elements, now performing explicit actions to prevent reordering, and open up for deployment of new technologies that naturally cause reordering. We propose TCP-Aix; a set of TCP modifications that improves the robustness of TCP to reordering and delay spikes. TCP-Aix decouples loss recovery and congestion control actions. We also present an algorithm called the winthresh algorithm for computing a duplicate acknowledgment threshold based on TCP buffer space and current send window size. The results show that TCP-Aix with the winthresh algorithm is able to maintain almost constant performance even in scenarios frequently displaying long reordering durations. It is also fair towards competing standards-compliant TCP flows.In wireless networks, where the links out of efficiency constraints are more error prone than wired links, the error and the reordering sensitivity of TCP have motivated link layer protocols that perform retransmissions and enforce in-order delivery. We investigate the potential gains of using a reordering robust TCP, like TCP-Aix, with a wireless link layer that allows out-of-order delivery, compared to using in-order delivery with a standardscompliant TCP. We found that the smoothness of TCP is strongly affected by the link layer configuration. In-order delivery leads to burstier traffic and larger network layer buffering needs, than out-of-order delivery and TCP-Aix. The interference and power consumption in foremost wireless networks make it important to reduce the communication overhead. The TCP receiver acknowledges each or every second segment. We study how to reduce the acknowledgment frequency while preserving throughput performance also in wireline networks where frequent acknowledgments generally are not problematic. To preserve throughput, the sender should use byte counting and be involved in determining the acknowledgment frequency. The results show that acknowledging four segments per send window is sufficient to maintain throughput performance also in wireline scenarios. This indicates that a lower acknowledgment frequency than provided through the delayed acknowledgment algorithm is possible today for general usage.A key service to the successful merging of traditional Internet technology and wireless cellular networks is Voice over IP (VoIP). Channels to be shared by both VoIP and TCP-based traffic is being considered for wireless cellular systems. It is challenging to provide VoIP over a shared wireless cellular channel, because VoIP is a low bitrate service with high demands on channel availability to bound the delay. The scheduling algorithm, controlling access to the channel, is central to achieve efficiency as well as to satisfy user demands. We study how a scheduler for a mix of VoIP and interactive (TCP-based) traffic should be designed for High Speed Downlink Packet Access (HSDPA). In particular, we find that slowly increasing the priority of a VoIP session relative TCP-based services is important to take advantage of the varying network conditions.

  • 332.
    Landström, Sara
    et al.
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Signaler och system.
    Ekström, Hannes
    Ericson Research.
    Larzon, Lars-Åke
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, EISLAB. Luleå tekniska universitet, Institutionen för system- och rymdteknik, Datavetenskap.
    Ludwig, Reiner
    Ericson Research.
    TCP-Aix: making TCP robust to reordering and delay variations2006Rapport (Övrigt vetenskapligt)
    Abstract [en]

    In this paper, we describe and evaluate TCP-Aix, a sender-side TCP algorithm designed to make TCP performance robust to packet reordering and delay. TCP-Aix consists of three novel components: (i) decoupling of loss recovery actions from congestion control actions, (ii) candid growth of the congestion window upon reception of dupacks, allowing for improved performance in reordering environments, and (iii) an algorithm for determining an appropriate dupthresh value. The results from our simulation study show that, by combining these three components, the performance of TCP-Aix is largely impervious even to the highest packet reordering rates investigated in this paper of 8\%, where the duration of the reordering is in the order 2-3 end-to-end RTTs. TCP-Aix outperforms a simulated state-of-the-art TCP sender as well as a TCP-NCR sender, the performance of which both display a much stronger dependence on packet reordering. Improved performance in the presence of delay spikes is also shown. Strengthened by simulation results, we further argue that the improved performance of TCP-Aix does not come at the expense of other, competing, TCP senders. Rather, the TCP-Aix senders utilise bandwidth that would otherwise have been left unutilised. We therefore believe that a gradual deployment of TCP-Aix would be feasible.

  • 333. Landström, Sara
    et al.
    Larzon, Lars-Åke
    Uppsala University.
    Bodin, Ulf
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Datavetenskap.
    Buffer management for TCP over HS-DSCH2005Rapport (Övrigt vetenskapligt)
    Abstract [en]

    In this paper we investigate the influence of buffer management for TCP on performance of the High Speed Downlink Channel (HS-DSCH) introduced in WCDMA release 5. HS-DSCH is a shared channel, but user data is buffered individually prior to the wireless link. Three queue management principles, e.g., passive queuing, the Packet Discard Prevention Counter (PDPC) method and the Random Early Detection (RED) algorithm were evaluated for a number of buffer sizes and scenarios. Also, a buffer large enough to prevent packets from being lost was included for reference. For round robin (RR) scheduling of radio-blocks, PDPC and the passive approach, that both manage to keep the buffer short, gave the best system goodput as well as the shortest average transfer times together with the excessively large buffer. With signal-to-interference ratio (SIR) scheduling, the strategy to avoid all packet losses, resulted in a lower system goodput than for the short buffers. As illustrated in this article, peak transfer rates may not be achieved with very small buffers, but buffers of 10-15 IP packets seem to represent a good trade-off between transfer rates, delay and system goodput. We would like to investigate how to make use of system parameters such as the current amount of data offered for HS-DSCH in total to regulate individual buffer sizes.

  • 334. Landström, Sara
    et al.
    Larzon, Lars-Åke
    Uppsala University.
    Bodin, Ulf
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Datavetenskap.
    Congestion control in a high-speed radio environment2004Ingår i: Proceedings of the International Conference on Wireless Networks, ICWN '04: Las Vegas, Nevada, USA, June 21 - 24, 2004 / [ed] Hamid R. Arabnia; Laurence Tianruo Yang; Chi-Hsiang Yeh, CSREA Press, 2004, s. 617-623Konferensbidrag (Refereegranskat)
    Abstract [en]

    This paper explores interactions between congestion control mechanisms at the transport layer and scheduling algorithms at the physical layer in the High-Speed Down-link Packet Access extension to WCDMA. Two different approaches to congestion control - TCP SACK and TFRC - are studied. We find that TCP SACK and TFRC in most respects perform the same way. SIR scheduling give a higher system throughput for both protocols than RR scheduling, but introduces delay variations that lead to spurious timeouts. The no feedback timeout of TFRC was shown to exhibit a similar sensitivity to delay spikes as the retransmit timeout in TCP SACK

  • 335.
    Larsson, Joakim
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Datavetenskap.
    Smart Booking: Concept for an automated booking solution2019Självständigt arbete på avancerad nivå (yrkesexamen), 300 hpStudentuppsats (Examensarbete)
    Abstract [sv]

    Med en ökande efterfrågan och redan ansträngda resurser står svenska hälso- och sjukvården inför stora utmaningar, vilken digitalisering kan underlätta. En av dessa utmaningar är hur man använder den begränsade mängden personalen så effektivt som möjligt för att möta kraven. Detta arbete avser att leverera ett förslag för ett bokningsverktyg som hjälper praktiker vid bokning av patienter, på ett tids- och resurseffektiv sätt, samtidigt som patientens preferenser respekteras. Den lösnings som presenteras ger praktiker möjlighet att hitta den “bästa” tiden, sett till både patientens och praktikers preferenser, i ett eller flera scheman. Systemet använder en poängfunktion för att bestämma vilken tid som är bäst. Vikterna som används definieras av användaren och går att konfiguera, vilket därmed ändrar beteendet och resultaten beroende av användarens behov och preferenser.

  • 336.
    Larsson, Mattias
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Datavetenskap.
    Mikrotjänst-arkitektur och dess skalbarhet2018Självständigt arbete på grundnivå (yrkesexamen), 10 poäng / 15 hpStudentuppsats (Examensarbete)
    Abstract [sv]

    Att designa mjukvaruapplikationer med en viss struktur kan ofta framhäva efterfrågade egenskaper. För att välja rätt arkitektur behövs ofta övervägningar, och ibland till och med kompromisser, göras om applikationens planerade karaktär. Det är ofta bra att i detta stadie ha en klar bild om vilka attribut en applikation önskas ha. Ett av de viktigare attributen på sikt är skalbarhet. Kunskapen om olika arkitekturers skalbarhet spelar en definitiv roll i designfasen, vilket avgör hur en applikation senare skalas. På senare år har mikrotjänst-arkitektur blivit ett populärt sätt att bygga mjukvara på där den höga skalbarheten sägs vara en bidragande faktor.

    Detta arbete har till syfte att undersöka skalbarheten hos mikrotjänst-arkitektur i förhållande till monolitisk arkitektur och visa hur detta kvalitetsattribut påverkas när en transformering från en monolit till en mikrotjänst-arkitektur görs. Arbetet har valt att utgå ifrån en existerande modul i en E-handelsplattform med öppen källkod. Modulen som transformerades till en mikrotjänst, skalades horisontellt för respektive arkitektur och applikations-version. Vid användandet av lämpliga verktyg, såsom Docker, visar resultatet att horisontell skalbarhet finns i högre grad hos mikrotjänst-arkitekturen och fortsätter därefter vara hög. Skalning av mikrotjänster kan göras med en högre precision av det som önskas förändras. Detta står i kontrast till den monolitiska strukturen, där skalning begränsas av prestandan av den miljö där mjukvaruapplikationen körs.

    Efter transformationen till en mikrotjänst-arkitektur ökade skalbarheten, då skalningsmetoden gjordes med mer finkornighet och isolering av den utvalda modulen. För att individuellt skala den monolitiska modulen horisontellt behövdes förändringen göras virtuellt med hjälp av bakgrundsprocesser. Denna lösning visar sig vara en indirekt skalning av hela den monolitiska strukturen. Utöver horisontell skalbarhet fokuserar utvärderingen av resultatet på kvalitativa attribut i form av simplicitet, autonomi och modularitet.

  • 337. Larzon, Lars-Åke
    et al.
    Bodin, Ulf
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Datavetenskap.
    Schelén, Olov
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Datavetenskap.
    Hints and notifications [for wireless links]2002Ingår i: 2002 IEEE Wireless Communications and Networking Conference record: Orlando, Florida, USA, 17 - 21 March 2002, Piscataway, NJ: IEEE Communications Society, 2002, s. 635-641Konferensbidrag (Refereegranskat)
    Abstract [en]

    With current Internet protocols, users may experience low and unpredictable forwarding quality at wireless links. This is due to varying link properties caused by changing radio conditions. Decreased forwarding quality can cause severe degradation in utilization. This is undesirable since forwarding capacity often is expensive at wireless links because of the limited radio spectrum. Allowing the application and transport layers to communicate with wireless link layers can improve the forwarding quality and utilization. We propose to enable inter-layer communication by adding hints and notifications (HAN) to the Internet architecture. Hints can be introduced and used without notifications, while notifications need hints or a similar mechanism to operate. By using IP options and ICMP messages to implement HAN, a backward-compatible partial deployment is possible. With HAN, the network layer becomes truly wireless friendly and the radio spectrum can be used efficiently while supporting both real-time and traditional data applications.

  • 338. Larzon, Lars-Åke
    et al.
    Degermark, Mikael
    Luleå tekniska universitet.
    Pink, Stephen
    Luleå tekniska universitet.
    Efficient use of wireless bandwidth for multimedia applications1999Ingår i: 1999 IEEE International Workshop on Mobile Multimedia Communications (MoMuC'99), San Diego, California, USA, November 15 - 17, 1999, Piscataway, NJ: IEEE Communications Society, 1999, s. 187-193Konferensbidrag (Refereegranskat)
    Abstract [en]

    Two rapidly evolving and merging technologies are the Internet and wireless data communications. Another trend is the increased use of real-time multimedia applications for audio and video communication. The most popular transport protocol among these delay sensitive applications is UDP (user datagram protocol), which is a lightweight protocol that provides multiplexing among user processes and has low protocol processing overhead. UDP's checksum policy is to protect either an entire packet including UDP and IP headers or nothing in the packet at all. This conforms badly with applications that prefers errors in the payload to the loss of whole packets. Many real-time applications fall into this category. We present a new protocol, UDP Lite, that provides the kind of protection often needed by these real time applications especially when they are run over wireless networks. UDP Lite increases the flexibility of UDP by providing an optionally partial checksum. Each packet can be optionally divided into a sensitive and an insensitive part by the sender. Errors in the sensitive part will cause packets to be discarded by the UDP Lite receiver, while errors in the insensitive part are ignored by UDP Lite. We show how UDP Lite uses a wireless network more efficiently for two different scenarios. By combining UDP Lite with compressed RTP, the gain can be even higher. Simulations show that the error rate of the network can increase by almost an order of magnitude without increasing the packet loss ratio. This enables cheaper network solutions for applications such as IP telephony

  • 339.
    Larzon, Lars-Åke
    et al.
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Datavetenskap.
    Degermark, Mikael
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Datavetenskap. Dept of CS&EE, University of Arizona.
    Pink, Stephen
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Datavetenskap. Dept of CS&EE, University of Arizona.
    Requirements on the TCP/IP protocol stack for real-time communication in wireless environments2001Ingår i: Quality of Service in Multiservice IP Networks: International Workshop, QoS-IP 2001 Rome, Italy, January 24-26, 2001 Proceedings / [ed] Marco Ajmone Marsan, Berlin: Encyclopedia of Global Archaeology/Springer Verlag, 2001, s. 273-283Konferensbidrag (Refereegranskat)
    Abstract [en]

    A strong trend in the Internet is to provide wireless Internet access to handheld devices. Radio spectrum is a scarce and expensive resource, and a wide-area cellular system that provides satisfying quality for a data service based on the traditional TCP/IP protocol stack will be expensive. This becomes especially problematic for real-time communication based on UDP. To design an economically viable system, dierent approaches are available. New protocols can be designed that take wireless systems into account. The Wireless Application Protocol (WAP) is an example of such a protocol. Alternatively, the existing TCP/IP protocols can be modified to better support cellular systems. The development of WAP is tempting since it does not have to modify the TCP/IP Protocol stack. However, to provide future proong, it is a better idea to base the protocol architecture for wireless on TCP/IP since this will be the dominant Internet protocol stack for years to come. This paper discusses requirements on various layers in the TCP/IP protocol stack to better support real-time data services. One key component is a transport layer designed to use limited bandwidth more efficiently for real-time services. Changes are required to other layers as well, but these can be deployed where needed without disturbing the rest of the Internet. By applying these changes, it becomes possible to provide cost efficient, real-time services based on IP in cellular systems.

  • 340.
    Larzon, Lars-Åke
    et al.
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, EISLAB.
    Degermark, Mikael
    Luleå tekniska universitet.
    Pink, Stephen
    Luleå tekniska universitet.
    UDP lite for real time multimedia applications1999Rapport (Övrigt vetenskapligt)
    Abstract [en]

    We introduce UDF Lite - a lightweight version of UDP with increased flexibility in the form of a partial checksum. It allows senders to specify packets as partially insensitive to errors. The coverage of the checksum is specified by the sending application on a per-packet basis. Because of its close relationship to UDP, UDP Lite is easily integrated into an existing UDP implementation. UDP is a simple best-effort transport protocol that adds multiplexing and an optional checksum to IP. Unlike TCP, UDP does not provide reliability, in-oflder delivery or congestion control, which has made it especially popular among delay-sensitive real-time applications. Audio/video applications often prefer damaged packets over lost packets. One way for an application to allow delivery of damaged packets is to disable the UDP checksum. This would mean, however, that important application-specific headers might pass unverified. Also, in the next version of IP, Ipv6, the UDP checksum is mandatory since there is no header checksum in Ipv6. These applications could benefit from using UDP Lite instead of UDP. By reflecting the UDP Lite policy with a partial checksum onto the link layer, the gain can be even higher

  • 341.
    Li, Di
    et al.
    School of Mechanical and Automotive Engineering, South China University of Technology.
    Zhai, Zhenkun
    School of Mechanical and Automotive Engineering, South China University of Technology.
    Pang, Zhibo
    ABB Corporate Research, Västerås.
    Vyatkin, Valeriy
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Datavetenskap. Aalto University, Department of Electronic Engineering & Automation.
    Liu, Chengliang
    Institute of Mechatronics, Shanghai Jiao Tong University .
    Synchronous-Reactive Semantic Modeling and Verification for Function Block Networks2017Ingår i: IEEE Transactions on Industrial Informatics, ISSN 1551-3203, E-ISSN 1941-0050, Vol. 13, nr 6, s. 3389-3398Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Owing to the semantic ambiguities, it has hindered the promotion of IEC 61499 in the field of industrial automation. In order to solve the thorny problem, this paper proposes an implementation scheme for performing formal modelling and simulation verification of semantics of functional block networks. Based on the synchrony hypothesis, the formal execution model is defined according to the fixed point semantics assuming that the behavior of a component functional block is monotonic. Subsequently, through specifying the evaluation of function blocks as a process of solving the least fixed point problem and transforming the network topology into a directed graph, a connectivity attenuation-based algorithm is put forward to ascertain the optimal scheduling policy of function blocks with the minimum overhead. Finally, by conducting the experiment for an industrial application, the feasibility and validity of the presented implementation scheme is proved.

  • 342.
    Lin, Hengyou
    et al.
    University of Auckland, Department of Electrical Engineering and Automation, Aalto University, Espoo.
    Sierla, Seppo
    Department of Automation and Systems Technology, School of Electrical Engineering, Aalto University, Department of Electrical Engineering and Automation, Aalto University, Espoo.
    Papakonstantinou, Nikolaos
    Aalto University, VTT Technical Research Centre of Finland, Espoo.
    Vyatkin, Valeriy
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Datavetenskap.
    A SysML profile supporting change orders in model driven engineering2015Ingår i: 2015 IEEE International Conference on Automation Science and Engineering (CASE): 24-28 Aug. 2015, Gothenburg, Sweden, Piscataway, NJ: IEEE Communications Society, 2015, s. 1054-1059, artikel-id 7294238Konferensbidrag (Refereegranskat)
    Abstract [en]

    One important capability for manufacturing enterprises is the ability to manage change orders, which are changes after the customer has placed the order. The change can be due to several reasons, such as misunderstanding of requirements or the inability of the supply chain to deliver parts, materials or subassemblies at an acceptable cost and lead time. The effective management of the latter kind of change requires linking design model elements to parts, which can be obtained from the supply chain or made in-house. In this paper, SysML is extended to support the said linkage, and based on these extensions a workflow is defined for handling the change. The model repository that underpins model driven engineering is exploited to partially automate the workflow and to relieve the change engineer from the need to understand the product structure or SysML

  • 343.
    Lin, Hengyou
    et al.
    University of Auckland, Department of Electrical Engineering and Automation, Aalto University, Espoo.
    Sierla, Seppo
    Department of Automation and Systems Technology, School of Electrical Engineering, Aalto University, Department of Electrical Engineering and Automation, Aalto University, Espoo.
    Papakonstantinou, Nikolaos
    Aalto University, VTT Technical Research Centre of Finland, Espoo.
    Vyatkin, Valeriy
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Datavetenskap.
    Change request management in model-driven engineering of industrial automation software2015Ingår i: IEEE 13th International Conference on Industrial Informatics (INDIN), 2015: Cambridge, United Kingdom, 22-24 July 2015, Piscataway, NJ: IEEE Communications Society, 2015, s. 1186-1191, artikel-id 7281904Konferensbidrag (Refereegranskat)
    Abstract [en]

    Change request management and Model Driven Engineering (MDE) are two key concepts for industrial automation software in today's competitive and fast changing environment. However, although there exist frameworks on general change management, they do not exploit the capabilities of MDE. This paper proposes a workflow to combine these two technologies, enabling the engineer responsible for the change to quickly and efficiently create analysis on the impact of the change, as well as the feasibility of a proposed solution. This result of the analysis is presented with concrete SysML model diagrams to better support decision making for a change request. One advantage of performing change management in SysML is the possibility to automate parts of the change analysis process; one step is automated as a proof-of-concept

  • 344.
    Lin, Hengyou
    et al.
    University of Auckland.
    Sorouri, Majid
    University of Auckland.
    Vyatkin, Valeriy
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Datavetenskap.
    Salčič, Zoran A.
    University of Auckland.
    Model-based customisation of intelligent mechatronic systems using SysML2013Ingår i: Proceedings of 2013 IEEE 18th International Conference on Emerging Technologies & Factory Automation (ETFA 2013): Cagliari, Italy, 10-13 September 2013, Piscataway, NJ: IEEE Communications Society, 2013, artikel-id 6648138Konferensbidrag (Refereegranskat)
    Abstract [en]

    This paper presents a model-based design approach for description of mechatronic systems using System Modeling Language (SysML) in order to facilitate modification and customization of existing intelligent mechatronic components and their use in new applications. This approach enables re-use and integration of the existing mechatronic software components to meet system design requirements and minimize the design and commissioning complexity of the control systems. A case study with a delta robot used in a colour sorting application demonstrates how its control system is tailored to meet the desired system behaviour

  • 345.
    Lind Nilsson, Rasmus
    Luleå tekniska universitet, Institutionen för system- och rymdteknik.
    Machine learning in logistics: Increasing the performance of machine learning algorithms on two specific logistic problems2017Självständigt arbete på grundnivå (yrkesexamen), 10 poäng / 15 hpStudentuppsats (Examensarbete)
    Abstract [sv]

    Data Ductus, ett multinationellt IT-konsultföretag vill utveckla en AI som övervakar ett logistiksystem och uppmärksammar fel. När denna AI är tillräckligt upplärd ska den föreslå korrigering eller automatiskt korrigera problem som uppstår.

    Detta projekt presenterar hur man arbetar med maskininlärningsproblem och ger en djupare inblick i hur kors-validering och regularisering, bland andra tekniker, används för att förbättra prestandan av maskininlärningsalgoritmer på det definierade problemet. Dessa tekniker testas och utvärderas i vårt logistiksystem på tre olika maskininlärnings algoritmer, nämligen Naïve Bayes, Logistic Regression och Random Forest.

    Utvärderingen av algoritmerna leder oss till att slutsatsen är att Random Forest, som använder korsvaliderade parametrar, ger bästa prestanda på våra specifika problem, medan de andra två faller bakom i varje testad kategori. Det blev klart för oss att kors-validering är ett enkelt, men kraftfullt verktyg för att öka prestanda hos maskininlärningsalgoritmer.

  • 346.
    Lindberg, Renny
    et al.
    Vrije Universiteit Brussel.
    Laine, Teemu H.
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Datavetenskap.
    Formative evaluation of an adaptive game for engaging learners of programming concepts in K-122018Ingår i: International journal of shape modeling, ISSN 0218-6543, Vol. 5, nr 2, s. 3-26Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    As the global demand for programmers is soaring, several countries have integrated programming into their K-12 curricula. Finding effective ways to engage children in programming education is an important objective. One effective method for this can be presenting learning materials via games, which are known to increase engagement and motivation. Current programming education games often focus on a single genre and offer one- size-fits-all experience to heterogeneous learners. In this study, we presented Minerva, a multi-genre (adventure, action, puzzle) game to engage elementary school students in learning programming concepts. The game content is adapted to play and learning styles of the player to personalize the gameplay. We conducted a formative mixed-method evaluation of Minerva with 32 Korean 6th grade students who played the game and compared their learning outcomes with 32 6th grade students who studied the same concepts using handouts. The results indicated that, in terms of retention, learning was equally effective in both groups. Furthermore, the game was shown to facilitate engagement among the students. These results, together with uncovered issues, will guide Minerva’s further development.

  • 347.
    Lindberg, Renny S. N.
    et al.
    Vrije Universiteit Brussel.
    Laine, Teemu H.
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Datavetenskap.
    Haaranen, Lassi
    Aalto University.
    Gamifying programming education in K‐12: A review of programming curricula in seven countries and programming games2019Ingår i: British Journal of Educational Technology, ISSN 0007-1013, E-ISSN 1467-8535, Vol. 50, nr 4, s. 1979-1995Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    An increasing number of countries have recently included programming education in their curricula. Similarly, utilizing programming concepts in gameplay has become popular in the videogame industry. Although many games have been developed for learning to program, their variety and their correspondence to national curricula remain an uncharted territory. Consequently, this paper has three objectives. Firstly, an investigation on the guidelines on programming education in K‐12 in seven countries was performed by collecting curricula and other relevant data official from governmental and non‐profit educational websites. Secondly, a review of existing acquirable games that utilize programming topics in their gameplay was conducted by searching popular game stores. Lastly, we compared the curricula and made suggestions as to which age group the identified games would be suitable. The results of this study can be useful to educators and curriculum designers who wish to gamify programming education.

  • 348.
    Lindgren, Anders
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Datavetenskap.
    Routing and quality of service in wireless and disruption tolerant networks2006Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    Wireless networks have become a common means of communication, and their popularity continues to rise as they enable communication in locations and settings where it was previously unfeasible. While promising many advantages, these networks also pose new challenges. The limited radio coverage, unreliable nature of the wireless channel, and mobility of network nodes can lead to frequent disruption of communication links, dynamic network topology, variable bandwidth availability, and high channel error rates. These challenges seek novel solutions to allow a growing number of wireless, mobile users to run applications and avail network services in ways similar to that in wired networks. This thesis makes contributions to three research areas related to wireless and disruption tolerant networks: (1) routing and forwarding to enable disruption tolerant communication in intermittently connected networks, (2) analysis of properties of human mobility and their effect on network protocols in disruption tolerant networks, and (3) quality of service mechanisms for wireless and mobile networks. In intermittently connected networks, there may rarely or never exist a fully connected path between a source and destination. This invalidates the basic assumption of end-to-end communication prevalent in the Internet and renders traditional routing protocols impractical. We propose PRoPHET, a novel routing protocol for intermittently connected networks. PRoPHET takes advantage of the mobility of nodes, and the predictability of that mobility for routing. The protocol and various forwarding strategies and queueing policies are studied in detail. The benefits of PRoPHET are evident on comparing its performance with contemporary work. Communication in intermittently connected and disruption tolerant networks is often highly dependent on the mobility of the nodes in the network. Thus, it is important to have good understanding of basic properties of user mobility in order to design network protocols that can operate under those conditions. Using real-life traces, we characterize human mobility patterns and their impact on forwarding algorithms in mobile networks with and without infrastructure. Finally, the thesis presents our work on two different aspects of quality of service in wireless and mobile networks. We evaluate four mechanisms for providing service differentiation in a wireless LAN, and give recommendations on their use in different scenarios. We propose a novel admission control scheme for mobile ad hoc networks, which is able to better cope with high mobility in the network compared to previous solutions.

  • 349. Lindgren, Anders
    et al.
    Almquist, A.
    Luleå tekniska universitet.
    Schelén, Olov
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Datavetenskap.
    Evaluation of quality of service schemes for IEEE 802.11 wireless LANs2001Ingår i: Proceedings: LCN 2001, 26th Annual IEEE Conference on Local Computer Networks : 14 - 16 November 2001, Tampa, Fl, Los Alamitos, Calif: IEEE Communications Society, 2001, s. 348-351Konferensbidrag (Refereegranskat)
    Abstract [en]

    This paper evaluates four mechanisms for providing service differentiation in IEEE 802.11 wireless LANs, the point coordinator function (PCF) of IEEE 802.11, the enhanced distributed coordinator function (EDCF) of the proposed IEEE 802.11e extension to IEEE 802.11, distributed fair scheduling (DFS), and Blackburst using the ns-2 simulator. The metrics used in the evaluation are throughput, medium utilization, collision rate, average access delay, and delay distribution for a variable load of real time and background traffic. The PCF performance is comparably low, while the EDCF performs much better. The best performance is achieved by Blackburst. The DFS provides relative differentiation and consequently avoids starvation of low priority traffic

  • 350. Lindgren, Anders
    et al.
    Almquist, Andreas
    Luleå tekniska universitet.
    Schelén, Olov
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Datavetenskap.
    Quality of service schemes for IEEE 802.11 wireless LANs: an evaluation2003Ingår i: Journal on spesial topics in mobile networks and applications, ISSN 1383-469X, E-ISSN 1572-8153, Vol. 8, nr 3, s. 223-235Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    This paper evaluates four mechanisms for providing service differentiation in IEEE 802.11 wireless LANs. The evaluated schemes are the Point Coordinator Function (PCF) of IEEE 802.11, the Enhanced Distributed Coordinator Function (EDCF) of the proposed IEEE 802.11e extension to IEEE 802.11, Distributed Fair Scheduling (DFS), and Blackburst. The evaluation was done using the ns-2 simulator. Furthermore, the impact of some parameter settings on performance has also been investigated. The metrics used in the evaluation are throughput, medium utilization, collision rate, average access delay, and delay distribution for a variable load of real time and background traffic. The simulations show that the best performance is achieved by Blackburst. PCF and EDCF are also able to provide pretty good service differentiation. DFS can give a relative differentiation and consequently avoids starvation of low priority traffic.

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