Change search
Refine search result
1234567 1 - 50 of 478
CiteExportLink to result list
Permanent link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
Rows per page
  • 5
  • 10
  • 20
  • 50
  • 100
  • 250
Sort
  • Standard (Relevance)
  • Author A-Ö
  • Author Ö-A
  • Title A-Ö
  • Title Ö-A
  • Publication type A-Ö
  • Publication type Ö-A
  • Issued (Oldest first)
  • Issued (Newest first)
  • Created (Oldest first)
  • Created (Newest first)
  • Last updated (Oldest first)
  • Last updated (Newest first)
  • Standard (Relevance)
  • Author A-Ö
  • Author Ö-A
  • Title A-Ö
  • Title Ö-A
  • Publication type A-Ö
  • Publication type Ö-A
  • Issued (Oldest first)
  • Issued (Newest first)
  • Created (Oldest first)
  • Created (Newest first)
  • Last updated (Oldest first)
  • Last updated (Newest first)
Select
The maximal number of hits you can export is 250. When you want to export more records please use the 'Create feeds' function.
  • 1.
    Abedin, Md. Zainal
    et al.
    University of Science and Technology Chittagong.
    Chowdhury, Abu Sayeed
    University of Science and Technology Chittagong.
    Hossain, Mohammad Shahadat
    University of Chittagong, Bangladesh.
    Andersson, Karl
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Computer Science.
    Karim, Razuan
    University of Science and Technology Chittagong.
    An Interoperable IP based WSN for Smart Irrigation Systems2017Conference paper (Refereed)
    Abstract [en]

    Wireless Sensor Networks (WSN) have been highly developed which can be used in agriculture to enable optimal irrigation scheduling. Since there is an absence of widely used available methods to support effective agriculture practice in different weather conditions, WSN technology can be used to optimise irrigation in the crop fields. This paper presents architecture of an irrigation system by incorporating interoperable IP based WSN, which uses the protocol stacks and standard of the Internet of Things paradigm. The performance of fundamental issues of this network is emulated in Tmote Sky for 6LoWPAN over IEEE 802.15.4 radio link using the Contiki OS and the Cooja simulator. The simulated results of the performance of the WSN architecture presents the Round Trip Time (RTT) as well as the packet loss of different packet size. In addition, the average power consumption and the radio duty cycle of the sensors are studied. This will facilitate the deployment of a scalable and interoperable multi hop WSN, positioning of border router and to manage power consumption of the sensors.

  • 2.
    Abedin, Md. Zainal
    et al.
    University of Science and Technology, Chittagong.
    Paul, Sukanta
    University of Science and Technology, Chittagong.
    Akhter, Sharmin
    University of Science and Technology, Chittagong.
    Siddiquee, Kazy Noor E Alam
    University of Science and Technology, Chittagong.
    Hossain, Mohammad Shahadat
    University of Chittagong, Bangladesh.
    Andersson, Karl
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Computer Science.
    Selection of Energy Efficient Routing Protocol for Irrigation Enabled by Wireless Sensor Networks2017In: Proceedings of 2017 IEEE 42nd Conference on Local Computer Networks Workshops, 445 Hoes Lane, P.O. Box 133, Piscataway, NJ 08855-1331, 2017, 75-81 p.Conference paper (Refereed)
    Abstract [en]

    Wireless Sensor Networks (WSNs) are playing remarkable contribution in real time decision making by actuating the surroundings of environment. As a consequence, the contemporary agriculture is now using WSNs technology for better crop production, such as irrigation scheduling based on moisture level data sensed by the sensors. Since WSNs are deployed in constraints environments, the life time of sensors is very crucial for normal operation of the networks. In this regard routing protocol is a prime factor for the prolonged life time of sensors. This research focuses the performances analysis of some clustering based routing protocols to select the best routing protocol. Four algorithms are considered, namely Low Energy Adaptive Clustering Hierarchy (LEACH), Threshold Sensitive Energy Efficient sensor Network (TEEN), Stable Election Protocol (SEP) and Energy Aware Multi Hop Multi Path (EAMMH). The simulation is carried out in Matlab framework by using the mathematical models of those algortihms in heterogeneous environment. The performance metrics which are considered are stability period, network lifetime, number of dead nodes per round, number of cluster heads (CH) per round, throughput and average residual energy of node. The experimental results illustrate that TEEN provides greater stable region and lifetime than the others while SEP ensures more througput.

  • 3.
    Abrishambaf, Reza
    et al.
    Department of Engineering Technology Miami University Hamilton, OH.
    Bal, Mert
    Department of Engineering Technology Miami University Hamilton, OH.
    Vyatkin, Valeriy
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Computer Science.
    Distributed Home Automation System Based on IEC 61499 Function Blocks and Wireless Sensor Networks2017In: 2017 IEEE International Conference on Industrial Technology (ICIT), Piscataway, NJ: Institute of Electrical and Electronics Engineers (IEEE), 2017, 1354-1359 p.Conference paper (Refereed)
    Abstract [en]

    In this paper, a distributed home automation system will be demonstrated. Traditional systems are based on a central controller where all the decisions are made. The proposed control architecture is a solution to overcome the problems such as the lack of flexibility and re-configurability that most of the conventional systems have. This has been achieved by employing a method based on the new IEC 61499 function block standard, which is proposed for distributed control systems. This paper also proposes a wireless sensor network as the system infrastructure in addition to the function blocks in order to implement the Internet-of-Things technology into the area of home automation as a solution for distributed monitoring and control. The proposed system has been implemented in both Cyber (nxtControl) and Physical (Contiki-OS) level to show the applicability of the solution.

  • 4.
    Abrishambaf, Reza
    et al.
    Department of Engineering Technology, Miami University, Hamilton, OH.
    Bal, Mert
    Department of Engineering Technology, Miami University, Hamilton, OH.
    Vyatkin, Valeriy
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Computer Science.
    Distributed home automation system based on IEC61499 function blocks and wireless sensor networks2017In: Proceedings of the IEEE International Conference on Industrial Technology, Piscataway, NJ: Institute of Electrical and Electronics Engineers (IEEE), 2017, 1354-1359 p., 7915561Conference paper (Refereed)
    Abstract [en]

    In this paper, a distributed home automation system will be demonstrated. Traditional systems are based on a central controller where all the decisions are made. The proposed control architecture is a solution to overcome the problems such as the lack of flexibility and re-configurability that most of the conventional systems have. This has been achieved by employing a method based on the new IEC 61499 function block standard, which is proposed for distributed control systems. This paper also proposes a wireless sensor network as the system infrastructure in addition to the function blocks in order to implement the Internet-of-Things technology into the area of home automation as a solution for distributed monitoring and control. The proposed system has been implemented in both Cyber (nxtControl) and Physical (Contiki-OS) level to show the applicability of the solution

  • 5.
    Andersson, Arne
    et al.
    Lunds universitet.
    Brodnik, Andrej
    Comment on "self-indexed sort"1996In: SIGPLAN notices, ISSN 0362-1340, E-ISSN 1558-1160, Vol. 31, no 8, 40-41 p.Article in journal (Other academic)
  • 6.
    Baghdo, Simon
    Luleå University of Technology, Department of Arts, Communication and Education.
    Game Telemtry: Store, Analyze and Improve UX in Game from Player-Choices2016Independent thesis Basic level (university diploma), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    During this project, the main objective was to store and analyze the user choices through game telemetry, in the game Bloodlines. With the goal to adjust the game for each member personally, for an improved user experience. This was done through a constructed database. By saving metrics of player choices and events such as: Most used weapon, attempts per session, session time periods, amount of deaths and highest rate of death cause. The results got analyzed with the control group settings in mind. Adjustments made were based on a fundamental foundation. In addition a web application with the functionality to enter and change the settings metrics in real time.

  • 7.
    Balasubramaniam, Sasitharan
    et al.
    Tampere University of Technology.
    Lyamin, Nikita
    Halmstad University.
    Kleyko, Denis
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Computer Science.
    Skurnik, Mikael
    University of Helsinki.
    Vinel, Alexey
    Halmstad University.
    Koucheryavy, Yevgeni
    Tampere University of Technology.
    Exploiting bacterial properties for multi-­‐hop nanonetworks2014In: IEEE Communications Magazine, ISSN 0163-6804, E-ISSN 1558-1896, Vol. 52, no 7, 184-191 p.Article in journal (Refereed)
    Abstract [en]

    Molecular communication is a relatively new communication paradigm for nanomachines where the communication is realized by utilizing existing biological components found in nature. In recent years, researchers have proposed using bacteria to realize molecular communication because the bacteria have, (i) the ability to swim and migrate between locations, (ii) the ability to carry DNA contents (i.e. plasmids), which could be utilized for information storage, and (iii) the ability to interact and transfer plasmids to other bacteria (one of this process is known as bacterial conjugation). However, current proposals for bacterial nanonetworks have not considered the internal structures of the nanomachines that can facilitate the use of bacteria as an information carrier. This article presents the types and functionalities of nanomachines that can be utilized in bacterial nanonetworks. A particular focus is placed on the bacterial conjugation and its support for multi-hop communication between nanomachines. Simulations of the communication process have also been evaluated, to analyze the quantity of bit received as well as the delay performances. Wet lab experiments have also been conducted to validate the bacterial conjugation process. The article also discusses potential applications of bacterial nanonetworks for cancer monitoring and therapy.

  • 8.
    Baniya, Rupak
    et al.
    Department of Electrical Engineering, School of Electrical Engineering, Aalto University.
    Maksimainen, Mikko
    Department of Electrical Engineering, School of Electrical Engineering, Aalto University.
    Sierla, Seppo
    Department of Automation and Systems Technology, School of Electrical Engineering, Aalto University.
    Pang, Cheng
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Computer Science.
    Yang, Chen-Wei
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Computer Science.
    Vyatkin, Valeriy
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Computer Science.
    Smart indoor lighting control: power, illuminance, and colour quality2014In: Proceedings: 2014 IEEE 23rd International Symposium on Industrial Electronics (ISIE) : Grand Cevahir Hotel and Convention Center Istambul, Turkey : 01 - 04 June, 2014, Piscataway, NJ: IEEE Communications Society, 2014, 1745-1750 p., 6864878Conference paper (Refereed)
    Abstract [en]

    This paper investigates the correlation between color quality and energy efficiency of indoor lighting control. The color quality, in terms of visual performance and comfort, is quantified using three measurements: illuminance, Color Rendering Index, and Correlated Color Temperature. Several experiments have been conducted to evaluate the potential energy savings of using different portions of light spectrum to obtain the optimal color quality. In particular, Light-Emitting Diodes are used as the lighting sources of the experimental luminaire. Moreover, the above quantification method and experimental results have been incorporated into a previously developed simulation framework for Building Automation and Control Systems, and smart lighting is used to adjust the tradeoff between comfort and energy consumption based on the presence of occupants. The results can be used to evaluate the viability of advanced lighting automation.

  • 9.
    Bediako, Peter Ken
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Computer Science.
    Long Short-Term Memory Recurrent Neural Network for detecting DDoS flooding attacks within TensorFlow Implementation framework.2017Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Distributed Denial of Service (DDoS) attacks is one of the most widespread security attacks to internet service providers. It is the most easily launched attack, but very difficult and expensive to detect and mitigate. In view of the devastating effect of DDoS attacks, there has been the increase on the adaptation of a network detection technique to reveal the presence of DDoS attack before huge traffic buildup to prevent service availability.

    Several works done on DDoS attack detection reveals that, the conventional DDoS attack detection methods based on statistical divergence is useful, however, the large surface area of the internet which serve as the main conduit for DDoS flooding attacks to occur, makes it difficult to use this approach to detect attacks on the network. Hence this research work is focused on using detection techniques based on a deep learning technique, because it is proven as the most effective detection technique against DDoS attacks.

    Out of the several deep neural network techniques available, this research focuses on one aspect of recurrent neural network called Long Short-Term Memory (LSTM) and TensorFlow framework to build and train a deep neural network model to detect the presence of DDoS attacks on a network. This model can be used to develop an Intrusion Detection System (IDS) to aid in detecting DDoS attacks on the network. Also, at the completion of this project, the expectation of the produced model is to have a higher detection accuracy rates, and a low false alarm rates.

    Design Science Research Methodology (DSRM) was used to carry out this project. The test experiment for this work was performed on CPU and GPU base systems to determine the base system's effect on the detection accuracy of the model.

    To achieve the set goals, seven evaluating parameters were used to test the model's detection accuracy and performance on both Central Processing Unit (CPU) and Graphics Processing Unit (GPU) systems.

    The results reveal that the model was able to produce a detection accuracy of 99.968% on both CPU and GPU base system which is better than the results by Yuan et al. [55] which is 97.606%. Also the results prove that the model's performance does not depend on the based system used for the training but rather depends on the dataset size. However, the GPU systems train faster than CPU systems. It also revealed that increasing the value of epochs during training does not affect the models detection accuracy but rather extends the training time.

    This model is limited to detecting 17 different attack types on maintaining the same detection accuracy mentioned above. Further future work should be done to increase the detecting attack type to unlimited so that it will be able to detect all attack types.

  • 10.
    Belyakov, Stanislav Leonidovich
    et al.
    Southern Federal University, Department of Applied Information Science Taganrog.
    Savelyeva, Marina
    Southern Federal University, Department of Applied Information Science Taganrog.
    Yan, Jeffrey
    Department of Electrical and Computer System Engineering, University of Auckland, University of Auckland.
    Vyatkin, Valeriy
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Computer Science.
    Adaptation of Material Flows in Mechanical Transportation Systems Based on Observation Experience2015In: IEEE TrustCom-BigDataSE-ISPA 2015: Helsinki, 20-22 Aug. 2015, Piscataway, NJ: IEEE Communications Society, 2015, 269-274 p., 7345659Conference paper (Refereed)
    Abstract [en]

    This paper investigates adaptation of material flows in mechanical transportation systems to the appearance of local overloads. The adaptation mechanism is based on the deflection of the forecast of experts who oversee the behavior of flows in the network. We propose a modified version of case-based reasoning, which uses the concept of imagination of situations. Unlike known methods, imaginative description of cases increases the reliability of decision-making. We provide a modification of the algorithm for dynamically building routing tables in distributed controllers of a transportation network. Analytic evaluation of the adaptation method's effectiveness is provided. The paper is concluded with outline of the implementation mechanism using a network of distributed controllers

  • 11.
    Belyakov, Stanislav Leonidovich
    et al.
    Southern Federal University, Department of Applied Information Science Taganrog.
    Savelyeva, Marina
    Southern Federal University, Department of Applied Information Science Taganrog.
    Yan, Jeffrey
    Department of Electrical and Computer System Engineering, University of Auckland, University of Auckland.
    Vyatkin, Valeriy
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Computer Science.
    Knowledge-based routing in mechanical transportation systems2014In: 12th IEEE International Conference on Industrial Informatics, INDIN 2014: Porto Alegre, Brazil, 27 - 30 July 2014, Piscataway, NJ: IEEE Communications Society, 2014, 48-53 p.Conference paper (Refereed)
    Abstract [en]

    This paper presents the ways of constructing routing algorithms in mechanical transport systems based on knowledge. It is assumed that the experts observing system behavior applies his experience by designating subsystems with a specific behavior. To create routing tables, a model of fuzzy temporal hypergraph was used. We consider fixed and dynamic routing, given modifications of Dijkstra's algorithm for the case of fuzzy temporal hypergraphs

  • 12.
    Bengtsson, Fredrik
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Computer Science.
    Algorithms for aggregate information extraction from sequences2007Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    In this thesis, we propose efficient algorithms for aggregate information extraction from sequences and multidimensional arrays. The algorithms proposed are applicable in several important areas, including large databases and DNA sequence segmentation. We first study the problem of efficiently computing, for a given range, the range-sum in a multidimensional array as well as computing the k maximum values, called the top-k values. We design two efficient data structures for these problems. For the range-sum problem, our structure supports fast update while preserving low complexity of range-sum query. The proposed top-k structure provides fast query computation in linear time proportional to the sum of the sizes of a two-dimensional query region. We also study the k maximum sum subsequences problem and develop several efficient algorithms. In this problem, the k subsegments of consecutive elements with largest sum are to be found. The segments can potentially overlap, which allows for a large number of possible candidate segments. Moreover, we design an optimal algorithm for ranking the k maximum sum subsequences. Our solution does not require the value of k to be known a priori. Furthermore, an optimal linear-time algorithm is developed for the maximum cover problem of finding k subsequences of consecutive elements of maximum total element sum.

  • 13.
    Bengtsson, Fredrik
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Computer Science.
    Efficient aggregate queries on data cubes2004Licentiate thesis, monograph (Other academic)
    Abstract [en]

    As computers are developing rapidly and become more available to the modern information society, the possibility and ability to handle large data sets in database applications increases. The demand for efficient algorithmic solutions to process huge amounts of information increases as the data sets become larger. In this thesis, we study the efficient implementation of aggregate operations on the data cube, a modern and flexible model for data warehouses. In particular, the problem of computing the k largest sum subsequences of a given sequence is investigated. An efficient algorithm for the problem is developed. Our algorithm is optimal for large values of the user-specified parameter k. Moreover, a fast in-place algorithm with good trade-off between update- and query-time, for the multidimensional orthogonal range sum problem, is presented. The problem studied is to compute the sum of the data over an orthogonal range in a multidimensional data cube. Furthermore, a fast algorithmic solution to the problem of maintaining a data structure for computing the k largest values in a requested orthogonal range of the data cube is also proposed.

  • 14.
    Bengtsson, Fredrik
    et al.
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Computer Science.
    Chen, Jingsen
    A note on ranking k maximum sums2005Report (Other academic)
    Abstract [en]

    In this paper, we design a fast algorithm for ranking the k maximum sum subsequences. Given a sequence of real numbers and an integer parameter k, the problem is to compute k subsequences of consecutive elements with the sums of their elements being the largest, second largest, ..., and the k:th largest among all possible range sums. For any value of k, 1 <= k <= n(n+1)/2, our algorithm takes O(n + k log n) time in the worst case to rank all such subsequences. Our algorithm is optimal for k <= n.

  • 15.
    Bengtsson, Fredrik
    et al.
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Computer Science.
    Chen, Jingsen
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Computer Science.
    Computing maximum-scoring segments in almost linear time2006In: Computing and Combinatorics: 12th annual international conference, COCOON 2006, Taipei, Taiwan, August 15 - 18, 2006 ; proceedings / [ed] Danny Z. Chen, Encyclopedia of Global Archaeology/Springer Verlag, 2006, 255-264 p.Conference paper (Refereed)
    Abstract [en]

    Given a sequence, the problem studied in this paper is to find a set of k disjoint continuous subsequences such that the total sum of all elements in the set is maximized. This problem arises naturally in the analysis of DNA sequences. The previous best known algorithm requires Θ(n log n) time in the worst case. For a given sequence of length n, we present an almost linear-time algorithm for this problem. Our algorithm uses a disjoint-set data structure and requires O(nα(n, n)) time in the worst case, where α(n, n) is the inverse Ackermann function.

  • 16.
    Bengtsson, Fredrik
    et al.
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Computer Science.
    Chen, Jingsen
    Computing maximum-scoring segments in almost linear time2006Report (Other academic)
    Abstract [en]

    Given a sequence, the problem studied in this paper is to find a set of k disjoint continuous subsequences such that the total sum of all elements in the set is maximized. This problem arises naturally in the analysis of DNA sequences. The previous best known algorithm requires n log n time in the worst case. For a given sequence of length n, we present an almost linear-time algorithm for this problem. Our algorithm uses a disjoint-set data structure and requires O(n a(n, n) ) time in the worst case, where a(n,n) is the inverse Ackermann function.

  • 17.
    Bengtsson, Fredrik
    et al.
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Computer Science.
    Chen, Jingsen
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Computer Science.
    Computing maximum-scoring segments optimally2007Report (Other academic)
    Abstract [en]

    Given a sequence of length n, the problem studied in this report is to find a set of k disjoint subsequences of consecutive elements such that the total sum of all elements in the set is maximized. This problem arises in the analysis of DNA sequences. The previous best known algorithm requires time proportional to n times the inverse Ackermann function of (n,n), in the worst case. We present a linear-time algorithm, which is optimal, for this problem.

  • 18.
    Bengtsson, Fredrik
    et al.
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Computer Science.
    Chen, Jingsen
    Computing the k maximum subarrays fast2004Report (Other academic)
    Abstract [en]

    We study the problem of computing the k maximum sum subarrays. Given an array of real numbers and an integer, k, the problem involves finding the k largest values of the sum from i to j of the array, for any i and j. The problem for fixed k=1, also known as the maximum sum subsequence problem, has received much attention in the literature and is linear-time solvable. In this paper, we develop an algorithm requiring time proportional to n times square root of k for an array of length n. Moreover, for two-dimensional version of the problem, which computes the k largest sums over all rectangular subregions of an m times n array of real numbers, we show that it can be solved efficiently in the worst case as well.

  • 19.
    Bengtsson, Fredrik
    et al.
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Computer Science.
    Chen, Jingsen
    Efficient algorithms for k maximum sums2004In: Algorithms and Computation: 15th International Symposium, ISAAC 2004 / [ed] Rudolf Fleischer; Gerhard Trippen, Berlin: Encyclopedia of Global Archaeology/Springer Verlag, 2004, 137-148 p.Conference paper (Refereed)
    Abstract [en]

    We study the problem of computing the k maximum sum subsequences. Given a sequence of real numbers (x1,x2,⋯,xn) and an integer parameter k, l ≤ k ≤ 1/2n(n -1), the problem involves finding the k largest values of Σl=ij xl for 1 ≤ i ≤ j ≤ n. The problem for fixed k = 1, also known as the maximum sum subsequence problem, has received much attention in the literature and is linear-time solvable. Recently, Bae and Takaoka presented a θ(nk)-time algorithm for the k maximum sum subsequences problem. In this paper, we design efficient algorithms that solve the above problem in O (min{k + n log2 n, n √k}) time in the worst case. Our algorithm is optimal for k ≥ n log2 n and improves over the previously best known result for any value of the user-defined parameter k. Moreover, our results are also extended to the multi-dimensional versions of the k maximum sum subsequences problem; resulting in fast algorithms as well

  • 20.
    Bengtsson, Fredrik
    et al.
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Computer Science.
    Chen, Jingsen
    Efficient algorithms for k maximum sums2006In: Algorithmica, ISSN 0178-4617, E-ISSN 1432-0541, Vol. 46, no 1, 27-41 p.Article in journal (Refereed)
    Abstract [en]

    We study the problem of computing the k maximum sum subsequences. Given a sequence of real numbers {x1,x2,...,xn} and an integer parameter k, 1 ≤ k ≤ 1/2n(n-1),the problem involves finding the k largest values of ∑ℓ=ijxℓ for 1 ≤ i ≤ j ≤ n.The problem for fixed k = 1, also known as the maximum sum subsequence problem, has received much attention in the literature and is linear-time solvable. Recently, Bae and Takaoka presented a Θ(nk)-time algorithm for the k maximum sum subsequences problem. In this paper we design an efficient algorithm that solves the above problem in O(min {k+nlog2n,n√k} ) time in the worst case. Our algorithm is optimal for k = Ω(n log 2 n) and improves over the previously best known result for any value of the user-defined parameter k < 1. Moreover, our results are also extended to the multi-dimensional versions of the k maximum sum subsequences problem; resulting in fast algorithms as well

  • 21.
    Bengtsson, Fredrik
    et al.
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Computer Science.
    Chen, Jingsen
    Ranking k maximum sums2007In: Theoretical Computer Science, ISSN 0304-3975, E-ISSN 1879-2294, Vol. 377, no 1-3, 229-237 p.Article in journal (Refereed)
    Abstract [en]

    Given a sequence of n real numbers and an integer parameter k, the problem studied in this paper is to compute k subsequences of consecutive elements with the sums of their elements being the largest, the second largest, and the kth largest among all possible range sums of the input sequence. For any value of k, 1 <= k <= n (n + 1)/2, we design a fast algorithm that takes O (n + k log n) time in the worst case to compute and rank all such subsequences. We also prove that our algorithm is optimal for k = O (n) by providing a matching lower bound.Moreover, our algorithm is an improvement over the previous results on the maximum sum subsequences problem (where only the subsequences are requested and no ordering with respect to their relative sums will be determined).Furthermore, given the fact that we have computed the fth largest sums, our algorithm retrieves the (l + 1)th largest sum in O (log n) time, after O (n) time of preprocessing.

  • 22.
    Bengtsson, Fredrik
    et al.
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Computer Science.
    Chen, Jingsen
    Space-efficient range-sum queries in OLAP2004In: Data Warehousing and Knowledge Discovery. Proceedings: 6th international conference, DaWaK 2004, Zaragoza, Spain, September 1 - 3, 2004 : proceedings / [ed] Yahiko Kambayashi; Mukesh Mohania; Wolfram Wöß, Encyclopedia of Global Archaeology/Springer Verlag, 2004, 87-96 p.Conference paper (Refereed)
    Abstract [en]

    In this paper, we present a fast algorithm to answer range-sum queries in OLAP data cubes. Our algorithm supports constant-time queries while maintaining sub-linear time update and using minimum space. Furthermore, we study the trade-off between query time and update time. The complexity for query is O(2ℓd) and for updates O((2ℓ2ℓ√n)d) on a data cube of nd elements, where ℓ is a trade-off parameter. Our algorithm improve over previous best known results

  • 23.
    Benko, I.
    et al.
    University of Waterloo.
    Brodnik, Andrej
    Architecture of KRPAN1996In: Elektrotehniski Vestnik, ISSN 0013-5852, Vol. 63, no 2, 65-68 p.Article in journal (Refereed)
    Abstract [en]

    In the paper we address the operation of an agency that provides information in a newspaper-like form on the information highway. We describe the software architecture and the physical layout of KRPAN, a kernel that provides the support necessary to operate such an agency. KRPAN is a distributed system which employs intelligent caching to improve space and network utilization. The implementation of KRPAN relies on standardized formats of data which permits usage of commonly available tools. At the end we touch legal and ethical questions and describe how KRPAN helps to solve them.

  • 24.
    Berglund, Tomas
    et al.
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering.
    Brodnik, Andrej
    Jonsson, Håkan
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Computer Science.
    Mrozek, Kent
    Staffansson, Mats
    Luleå tekniska universitet.
    Söderkvist, Inge
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Mathematical Science.
    Minimum curvature variation B-splines: validation of a path-planning model2004Report (Other academic)
  • 25.
    Berglund, Tomas
    et al.
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering.
    Brodnik, Andrej
    Jonsson, Håkan
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Computer Science.
    Staffansson, Mats
    Luleå tekniska universitet.
    Söderkvist, Inge
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Mathematical Science.
    Planning smooth and obstacle-avoiding b-spline paths for autonomous mining vehicles2010In: IEEE Transactions on Automation Science and Engineering, ISSN 1545-5955, E-ISSN 1558-3783, Vol. 7, no 1, 167-172 p.Article in journal (Refereed)
    Abstract [en]

    We study the problem of automatic generation of smooth and obstacle-avoiding planar paths for efficient guidance of autonomous mining vehicles. Fast traversal of a path is of special interest. We consider four-wheel four-gear articulated vehicles and assume that we have an a priori knowledge of the mine wall environment in the form of polygonal chains. Computing quartic uniform B-spline curves, minimizing curvature variation, staying at least at a proposed safety margin distance from the mine walls, we plan high speed paths.

  • 26.
    Berglund, Tomas
    et al.
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Embedded Internet Systems Lab.
    Erikson, Ulf
    Luleå tekniska universitet.
    Jonsson, Håkan
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Computer Science.
    Mrozek, Kent
    Navigator AB.
    Söderkvist, Inge
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Mathematical Science.
    Automatic generation of smooth paths bounded by polygonal chains2001In: CIMCA 2001: 2001 international conference on computational intelligence for modelling, control & automation : 9-11 July 2001, Las Vegas, Nevada, USA : proceedings / [ed] M. Mohammadian, CIMCA , 2001, 528-535 p.Conference paper (Refereed)
  • 27.
    Berglund, Tomas
    et al.
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Embedded Internet Systems Lab.
    Greppe, Anders
    Thorén, Johan
    Papp, John
    Curve and surface fitting to measured data with a B-spline approach1999Report (Other academic)
    Abstract [en]

    Report in the Project course in Mathematics, MAM088, 1998/1999. Department of Mathematics, Luleå University of Technology, Sweden

  • 28. Berglund, Tomas
    et al.
    Jonsson, Håkan
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Computer Science.
    Söderkvist, Inge
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Mathematical Science.
    An obstacle-avoiding minimum variation B-spline problem2003In: Proceedings: 2003 International Conference on Geometric Modeling and Graphics, GMAG 2003 ; 16 - 18 July 2003, London, England, Los Alamitos, Calif: IEEE Communications Society, 2003, 156-161 p.Conference paper (Refereed)
    Abstract [en]

    We study the problem of computing a planar curve, restricted to lie between two given polygonal chains, such that the integral of the square of arc-length derivative of curvature along the curve is minimized. We introduce the minimum variation B-spline problem, which is a linearly constrained optimization problem over curves, defined by B-spline functions only. An empirical investigation indicates that this problem has one unique solution among all uniform quartic B-spline functions. Furthermore, we prove that, for any B-spline function, the convexity properties of the problem are preserved subject to a scaling and translation of the knot sequence defining the B-spline.

  • 29.
    Berglund, Tomas
    et al.
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Embedded Internet Systems Lab.
    Jonsson, Håkan
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Computer Science.
    Söderkvist, Inge
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Mathematical Science.
    The problem of computing an obstacle-avoiding minimum variation B-spline2003Report (Other academic)
    Abstract [en]

    We study the problem of computing a planar curve restricted to lie between two given polygonal chains such that the integral of the square of arc- length derivative of curvature along the curve is minimized. We introduce the Minimum Variation B-spline problem which is a linearly constrained optimization problem over curves defined by B-spline functions only. An empirical investigation indicates that this problem has one unique solution among all uniform quartic B-spline functions. Furthermore, we prove that, for any B-spline function, the convexity properties of the problem are preserved subject to a scaling and translation of the knot sequence defining the B-spline.

  • 30.
    Berglund, Tomas
    et al.
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering.
    Strömberg, Thomas
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Mathematical Science.
    Jonsson, Håkan
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Computer Science.
    Söderkvist, Inge
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Mathematical Science.
    Epi-convergence of minimum curvature variation B-splines2003Report (Other academic)
    Abstract [en]

    We study the curvature variation functional, i.e., the integral over the square of arc-length derivative of curvature, along a planar curve. With no other constraints than prescribed position, slope angle, and curvature at the endpoints of the curve, the minimizer of this functional is known as a cubic spiral. It remains a challenge to effectively compute minimizers or approximations to minimizers of this functional subject to additional constraints such as, for example, for the curve to avoid obstacles such as other curves. In this paper, we consider the set of smooth curves that can be written as graphs of three times continuously differentiable functions on an interval, and, in particular, we consider approximations using quartic uniform B- spline functions. We show that if quartic uniform B-spline minimizers of the curvature variation functional converge to a curve, as the number of B-spline basis functions tends to infinity, then this curve is in fact a minimizer of the curvature variation functional. In order to illustrate this result, we present an example of sequences of B-spline minimizers that converge to a cubic spiral.

  • 31.
    Birk, Wolfgang
    et al.
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Signals and Systems.
    Eliasson, Jens
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Embedded Internet Systems Lab.
    Lindgren, Per
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Embedded Internet Systems Lab.
    Osipov, Evgeny
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Computer Science.
    Riliskis, Laurynas
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Computer Science.
    Road surface networks technology enablers for enhanced ITS2010In: 2010 IEEE Vehicular Networking Conference, VNC 2010: Jersey City, NJ ; 13-15 Dec 2010, Piscataway, NJ: IEEE Communications Society, 2010, 152-159 p.Conference paper (Refereed)
    Abstract [en]

    The increased need for mobility has led to transportation problems like congestion, accidents and pollution. In order to provide safe and efficient transport systems great efforts are currently being put into developing Intelligent Transport Systems (ITS) and cooperative systems. In this paper we extend proposed solutions with autonomous on-road sensors and actuators forming a wireless Road Surface Network (RSN). We present the RSN architecture and design methodology and demonstrate its applicability to queue-end detection. For the use case we discuss the requirements and technological solutions to sensor technology, data processing and communication. In particular the MAC protocol is detailed and its performance assessed through theoretical verification. The RSN architecture is shown to offer a scalable solution, where increased node density offers more precise sensing as well as increased redundancy for safety critical applications. The use-case demonstrates that RSN solutions may be deployed as standalone systems potentially integrated into current and future ITS. RSN may provide both easily deployable and cost effective alternatives to traditional ITS (with a direct impact independent of penetration rate of other ITS infrastructures - i.e., smart vehicles, safe spots etc.) as well as provide fine grain sensory information directly from the road surface to back-end and cooperative systems, thus enabling a wide range of ITS applications beyond current state of the art.

  • 32.
    Birk, Wolfgang
    et al.
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Signals and Systems.
    Osipov, Evgeny
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Computer Science.
    On the design of cooperative road infrastructure systems2008In: Reglermöte 2008: proceedings / [ed] Thomas Gustafsson; Wolfgang Birk; Andreas Johansson, Luleå: Luleå tekniska universitet, 2008Conference paper (Other academic)
    Abstract [en]

    This paper discusses the design of cooperative road infrastructure systems for infrastructure-based driving support functions. The background of such systems is mapped out and it is shown that there is a need for a cross disciplinary approach. Using an example of a support function, namely the overtaking support, it is shown that such a system is feasible. The different challenges and technological problems that are identified are given and the future work is indicated.

  • 33.
    Birk, Wolfgang
    et al.
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Signals and Systems.
    Osipov, Evgeny
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Computer Science.
    Eliasson, Jens
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Embedded Internet Systems Lab.
    iRoad - cooperative road infrastructure systems for driver support2009In: 16th World Congress and Exhibition on Intelligent Transport Systems 2009: 16th ITS World Congress ; Stockholm, Sweden, 21 - 25 September 2009, Red Hook: Curran Associates, Inc., 2009Conference paper (Refereed)
    Abstract [en]

    This paper discusses the design and implementation of a cooperative road infrastructure systems, which uses an intelligent road surface. Using an overtaking assist feature as an example it is shown how such a feature can be designed and implemented on a road infrastructure and integrated with drivers and passengers using IMS. The feasibility of this feature is assessed from a functional and communication perspective. Moreover, first results from real-life tests on the Swedish highway E4 are presented which motivate the next research and development steps.

  • 34.
    Birk, Wolfgang
    et al.
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Signals and Systems.
    Osipov, Evgeny
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Computer Science.
    Riliskis, Laurynas
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Computer Science.
    Hesler, Alban
    NEC.
    Modular design and performance ranking of communication protocols2009Report (Other academic)
    Abstract [en]

    In this deliverable we present a systematic approach towards designing modularized protocols and rank a contribution of their components to the overall system performance. In the nutshell, this approach is based onthree steps: 1.) identifying adjustable parameters in existing protocols, 2.) ranking their influence on the system-level performance metrics and 3.) defining protocol modules exposing the parameters of the highest rank. To this end we present the definition of the components for constructing MAC protocols based on ranking of the impact of adjustable parameters on the overall system performance. We also overview a ranking method for functional blocks of protocols on the routing layer.

  • 35.
    Björklund, Thomas
    et al.
    Luleå tekniska universitet.
    Brodnik, Andrej
    Nordlander, Johan
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Computer Science.
    Formal verification of a trie-based data structure2005Conference paper (Refereed)
  • 36.
    Bladh, Thomas
    et al.
    Luleå tekniska universitet.
    Carr, David A
    Luleå tekniska universitet.
    Kljun, Matjaz
    University of Primorska.
    The effect of animated transitions on user navigation in 3D tree-maps2005In: Proceedings: Ninth International Conference on Information Visualisation : 06 - 08 July 2005, London, England / [ed] Ebad Banissi, Los Alamitos, Calif: IEEE Communications Society, 2005, 297-305 p.Conference paper (Refereed)
    Abstract [en]

    This paper describes a user study conducted to evaluate the use of smooth animated transitions between directories in a three-dimensional, tree-map visualization. We looked specifically at the task of returning to a previously visited directory after either an animated or instantaneous return to the root location. The results of the study show that animation is a double-edged sword. Even though users take more shortcuts, they also make more severe navigational errors. It seems as though the promise of a more direct route to the target directory, which animation provides, somehow precludes users who navigate incorrectly from applying a successful recovery strategy.

  • 37.
    Blech, Jan Olaf
    et al.
    RMIT University, Melbourne.
    Lindgren, Per
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Embedded Internet Systems Lab.
    Pereira, David
    ISEP, Instituto Superior de Engenharia do Porto.
    Vyatkin, Valeriy
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Computer Science.
    Zoitl, Alois
    fortiss GmbH, Munich.
    A Comparison of Formal Verification Approaches for IEC 614992016In: 2016 IEEE 21st International Conference on Emerging Technologies and Factory Automation (ETFA): Berlin, 6-9 Sept. 2016, Piscataway, NJ: IEEE conference proceedings, 2016, 7733636Conference paper (Refereed)
    Abstract [en]

    Engineering and computer science have come up with a variety of techniques to increase the confidence in systems, increase reliability, facilitate certification, improve reuse and maintainability, improve interoperability and portability. Among them are various techniques based on formal models to enhance testing, validation and verification. In this paper, we are concentrating on formal verification both at runtime and design time of a system. Formal verification of a system property at design time is the process of mathematically proving that the property indeed holds. At runtime, one can check the validity of the property and report deviations by monitoring the system execution. Formal verification relies on semantic models, descriptions of the system and its properties. We report on ongoing verification work and present two different approaches for formal verification of IEC 61499-based programs. We provide two examples of ongoing work to exemplify the design and the runtime verification approaches

  • 38.
    Bodin, Ulf
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Computer Science.
    Quality issues in Internet packet forwarding2003Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    This thesis addresses quality issues in Internet Protocol (IP) packet forwarding. In IP networks, queue mechanisms and scheduling can be used to construct multiple forwarding behaviors. Thereby, both relative and independent services can be offered to Internet users. Independent services offer forwarding qualities known beforehand. Users are assumed to explicitly request admission to an independent service from their network provider. With relative services, users switch between these services to find one that provides an appealing balance between forwarding quality and cost. The thesis makes contributions to three research areas related to forwarding quality in IP networks; differentiating forwarding mechanisms, admission control for differentiated services, and forwarding quality in radio networks carrying Internet traffic. It contributes to the first research area with definitions of three recommendations related to offering loss-rate differentiation (i.e., multiple drop precedence levels). These recommendations are; (1) the total forwarding quality at congested links should not be degraded due to actions taken to create loss-rate differentiation, (2) traffic at high drop precedence levels should always be given a useful share of available forwarding resources, and (3) users should be able to predict the change in loss-rates when switching between drop precedence levels. We specify and evaluate properties of queue mechanisms following these recommendations. Also, as a contribution to the first research area, a new set of forwarding behaviors is specified and analyzed. These forwarding behaviors are suitable for rate-adaptive and delay-sensitive applications with limited loss-tolerance. Applications needing loss-free forwarding of specific packets can be said to have limited loss tolerance. We define and evaluate a scheduling mechanism creating these forwarding behaviors that can be implemented efficiently. The contribution to the second research area is a mechanism for admission control giving assurances on loss-rates to rate varying applications is defined. With this mechanism, dynamic per-link admission thresholds are used to limit committed aggregate rates. To allow for high link utilization through statistical multiplexing we specify a method to adjust these thresholds using low impact traffic monitoring mechanisms commonly available in legacy routers. In radio networks carrying IP traffic, radio transmissions can be scheduled differently to balance spectrum utilization and the forwarding quality provided. Also, parameters settings can be used to optimize the forwarding quality in radio networks for certain transport protocols and applications. This thesis analyses delay spikes experienced by IP traffic in cellular radio networks. We evaluate two different radio-block scheduling mechanisms’ impact on two versions of the Transmission Control Protocol (TCP) (i.e., TCP Sack and TCP Eifel). The evaluation contributes to the third research area by revealing basic dependencies between scheduling, interference, and congestion control mechanisms implemented by TCP. Finally, the thesis contributes to the third research area by proposing extensions to the Internet architecture for inter-layer communication. These extensions allow applications and transport protocols to exchange information with radio link layers. Such information exchange can be used to improve the forwarding quality and to customize data and transport features for current radio conditions.

  • 39.
    Bodin, Ulf
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Computer Science.
    Queue mechanisms for differentiation in the Internet2000Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    This thesis addresses loss-rate differentiation in the Internet. Loss-rate differentiation can be offered by tagging packets with different levels of drop precedence. Multiple drop precedence levels can be used to provide relative service levels and to assure forwarding capacity in the Internet. Assured services offer forwarding qualities known beforehand. This makes them more predictable than relative services. Users are assumed to explicitly request an assured service from their network provider for traffic up to a specified rate. With relative service levels, users switch between these levels to find one that provides an appealing balance between forwarding quality and cost. The policy for drop precedence probabilities defines the type of loss-rate differentiation pro-vided. Sheltered loss-rate (SLR) differentiation is offered by strictly giving drops to traffic at high drop precedence levels. Sheltering means that traffic at a low drop precedence level is protected from losses caused by traffic at higher levels. Such protection is required for assured services. Relative loss-rate (RLR) differentiation is offered when drop precedence probabilities are rela-tively distributed between drop precedence levels. Offering fixed relations in these probabilities further refines RLR differentiation, resulting in proportional loss-rate (PLR) differentiation. This thesis defines three recommendations associated with providing loss-rate differentiation. Such differentiation can be created with queue mechanisms. We specify and evaluate the proper-ties of differentiating queue mechanisms that make them capable of meeting the recommenda-tions defined. These evaluations are made with simulations. Firstly, the total forwarding quality at congested links should not be degraded due to actions taken to create loss-rate differentiation. The total forwarding quality includes packet loss patterns and delay variations. These quality metrics are high when packet drops are delayed. When pro-viding loss-rate differentiation, drops can be delayed through only dropping packets as they ar-rive. Dropping packets from queues enables immediate drops. This thesis shows that with imme-diate drops less bursty loss patterns and lower delay variations are achieved than with delayed drops. Secondly, traffic at high drop precedence levels should always be given a useful share of avail-able forwarding resources. Such traffic may experience high loss-rates, but should not become starved. Traffic at high levels may become starved due to overloading of traffic at lower levels when creating SLR differentiation. Starvation can be avoided with proper control of low drop precedence traffic. This control may, however, fail due to changes in the network routing topol-ogy, inaccurate admission control, etc. To avoid starvation without relying on proper traffic con-trol, this thesis presents a new queuing mechanism that falls back from offering sheltering to providing RLR differentiation during overloading of low drop precedence traffic. Thirdly, PLR differentiation should be predictable. Users should be able to predict the change in loss-rates when switching between drop precedence levels. PLR differentiation requires relations in loss-rates to be fixed to pre-configured target ratios. Running estimates of loss-rate ratios can be used as feedback to adjust towards these targets if the actual loss-rate ratios deviate from the target ratios. To provide predictable PLR differentiation, these estimates need to be accurate and stable at varying traffic loads. Moreover, they need to detect traffic load variations rapidly. This thesis presents a loss-rate estimator that provides accurate, stable and rapid detection of loss-rate ratios at varying traffic loads.

  • 40.
    Bodin, Ulf
    et al.
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Computer Science.
    Andersson, Ulf
    Dadhich, Siddharth
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Embedded Internet Systems Lab.
    Uhlin, Erik
    Volvo Construction Equipment.
    Marklund, Ulf
    Boliden AB.
    Häggström, Derny
    Oryx Simulations AB.
    Remote Controlled Short-Cycle Loading of Bulk Material in Mining Applications2015Article in journal (Refereed)
    Abstract [en]

    High-capacity wireless IP networks with limited delays are nowadays being deployed in both underground and open-pit mines. This allows for advanced remote control of mining machinery with improved feedback to operators and extensive monitoring of machine status, wear and fatigue. Wireless connectivity varies however depending on channel impairments caused by obstacles, multi-path fading and other radio issues. Therefore remote control and monitoring should be capable of adapting their sending rates to handle variations in communications quality. This paper presents key challenges in advanced remote control and monitoring of working machines via high-capacity wireless IP networks in mining environments. We reason about these challenges in context of underground short-cycle load, haul and dump operation with large-volume built wheel-loaders and present a generic communication solution for an operator assistance concept capable of adapting to varying communication properties

  • 41.
    Bodin, Ulf
    et al.
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Computer Science.
    Jonsson, Andreas
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Signals and Systems.
    Schelén, Olov
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Computer Science.
    On creating proportional loss-rate differentiation: predictability and performance2001In: Quality of Service - IWQoS 2001: 9th International Workshop Karlsruhe, Germany, June 6-8, 2001 Proceedings / [ed] Lars Wolf, Berlin: Encyclopedia of Global Archaeology/Springer Verlag, 2001, 372-386 p.Conference paper (Refereed)
    Abstract [en]

    Recent extensions to the Internet architecture allow assignment of different levels of drop precedence to IP packets. This paper examines differentiation predictability and implementation complexity in creation of proportional lossrate (PLR) differentiation between drop precedence levels. PLR differentiation means that fixed loss-rate ratios between different traffic aggregates are provided independent of traffic loads. To provide such differentiation, running estimates of loss-rates can be used as feedback to keep loss-rate ratios fixed at varying traffic loads. In this paper, we define a loss-rate estimator based on average drop distances (ADDs). The ADD estimator is compared with an estimator that uses a loss history table (LHT) to calculate loss-rates. We show, through simulations, that the ADD estimator gives more predictable PLR differentiation than the LHT estimator. In addition, we show that a PLR dropper using the ADD estimator can be implemented efficiently.

  • 42.
    Bodin, Ulf
    et al.
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Computer Science.
    Schelén, Olov
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Computer Science.
    Drop strategies and loss-rate differentiation2001In: Proceedings: Ninth International Conference on Network Protocols, ICNP 2001 : 11 - 14 November 2001, Riverside, California, USA, Los Alamitos, Calif: IEEE Communications Society, 2001, 146-154 p.Conference paper (Refereed)
    Abstract [en]

    When offering loss-rate differentiation in IP networks, the drop strategy used can have a considerable influence on packet loss and delay. In particular, a strategy of dropping packets only as they arrive can cause bursty loss patterns and high jitter. When only arriving packets are dropped, the router may need to wait for low priority packets to arrive before dropping any packet. This results in larger queue oscillation than if low priority packets were dropped immediately from the queue. Queue oscillation gives bursty loss patterns and delay jitter. We present simulations showing that dropping packets from the queue gives smoother loss patterns and less jitter than if packets are dropped only as they arrive. These simulations cover both TCP Sack and TCP Reno. WRED with and without the gentle modification is used to make drop decisions.

  • 43.
    Bodin, Ulf
    et al.
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Computer Science.
    Schelén, Olov
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Computer Science.
    Pink, Stephen
    Luleå tekniska universitet.
    Load-tolerant differentiation with active queue management2000In: Computer communication review, ISSN 0146-4833, E-ISSN 1943-5819, Vol. 30, no 3, 4-16 p.Article in journal (Refereed)
    Abstract [en]

    Current work in the IETF aims at providing service differentiation on the Internet. One proposal is to provide loss differentiation by assigning levels of drop procedence to IP packets. In this paper, we evaluate the active queue management (AQM) mechanisms RED In and Out (RIO) and Weighted RED (WRED) in providing levels of drop precedence under different loads. For low drop precedence traffic, FIO and WRED can be configured to offer sheltering (i.e., low drop precedence traffic is protected from losses caused by higher drop precedence traffic). However, if traffic control fails or is inaccurate, such configurations can cause starvation of traffic at high drop precedence levels. Configuring WRED to instead offer relative differentiation can eliminate the risk of starvation. However, WRED cannot, without reconfiguration, both offer sheltering when low drop precedence traffic is properly controlled and avoid starvation at overload of low drop precedence traffic. To achieve this, we propose a new AQM mechanism, WRED with Thresholds (WRT). The benefit of WRT is that, without reconfiguration, it offers sheltering when low drop precedence traffic is properly controlled and relative differentiation otherwise. We present simulations showing that WRT has these properties.

  • 44.
    Bodin, Ulf
    et al.
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Computer Science.
    Schelén, Olov
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Computer Science.
    Vemmervik, Claes
    Operax AB.
    End-to-End QoS control architectures from a wholesale and retail perspective: benefits and challenges2006Conference paper (Refereed)
  • 45.
    Bodin, Ulf
    et al.
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Computer Science.
    Simonsson, Arne
    Ericsson Research, Luleå.
    Effects on TCP from radio-block scheduling in WCDMA high speed downlink shared channels2003In: Quality for all: 4th COST 263 International Workshop on Quality of Future Internet Services, QoFIS 2003, Stockholm, Sweden, October 1-2, 2003 : proceedings / [ed] Gunnar Klarlsson; Michael I. Smirnov, Berlin: Encyclopedia of Global Archaeology/Springer Verlag, 2003, 214-223 p.Conference paper (Refereed)
    Abstract [en]

    Avoiding delay jitter is essential to achieve high throughput for TCP. In particular, delay spikes can cause spurious timeouts. Such timeouts force TCP into slow-start, which may reduce congestion window sizes drastically. Consequently, there may not always be data available for transmission on bottleneck links. For HS-DSCH, jitter can occur due to varying interference. Also, properties of the radio-block scheduling influence the jitter. We evaluate, through simulations, effects on TCP from scheduling. Our evaluation shows that round-robin (RR) schedulers can give more jitter than SIR schedulers. SIR schedulers discriminates low SIR users to improve spectrum utilization while RR schedulers distribute transmission capacity fairly. The high jitter with RR scheduling cause however both lower utilization and decreased fairness in throughput among users than with SIR scheduling. The Eifel algorithm makes TCP more robust against delay spikes and reduces thereby these problems

  • 46.
    Bodin, Ulf
    et al.
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Computer Science.
    Wolosz, Krzysztof
    Proportional throughput differentiationwith cognitive load-control on WSN channels2015In: EURASIP Journal on Wireless Communications and Networking, ISSN 1687-1472, E-ISSN 1687-1499, no 1, 186Article in journal (Refereed)
    Abstract [en]

    Wireless sensor networks are nowadays used in various applications to facilitate monitoring and actuation tasks, e.g., for smart grids and industrial automation. Some of these applications require guarantees or at least assurances on reliability. Such applications expect predictable throughput and delay, which are hard to maintain in environments with changing radio conditions. QoS-aware MAC protocols capable of handling such environments are well explored. They require however protocol changes and are therefore difficult to deploy. This paper presents an application layer forwarding service that offers proportional differentiation while limiting network load to preserve high utilization and predictability. Demands for capacity are expressed as fractions of the overall channel throughput. We show that this service can be implemented with a cognitive load controller (CLC) based on fuzzy logic and quality assessed with utility functions for application layer packet loss and throughput. We evaluate the CLC for 802.15.4 with CSMA/CA through NS-3 simulations showing that it offers the intended service while adjusting load for high overall throughput and low delay

  • 47.
    Booth, Todd
    et al.
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Computer Science.
    Andersson, Karl
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Computer Science.
    DNS DDoS Mitigation, via DNS Timer Design Changes2017In: Future Network Systems and Security: Third International Conference, FNSS 2017, Gainesville, FL, USA, August 31 - September 2, 2017, Proceedings / [ed] Robin Doss, Welwyn Piramuthu, Wei Zhou, Springer, 2017, 43-55 p.Conference paper (Refereed)
    Abstract [en]

    DDoS attacks have been a problem since 2000. In October 2016, there was a major DDoS attack against the service provider Dyn’s DNS service, which took the service down. This was one of the largest bandwidth DDoS attack ever documented, with attack bandwidth over 650 Gbps. By taking down just Dyn’s DNS service, clients could not obtain the IP addresses, of the organizations hosting their DNS with Dyn, such as Twitter. Our contribution is that we have found a way to mitigate the effect of DDoS attacks against DNS services. We only require some very small algorithm changes, in the DNS protocol. More specifically, we propose to add two additional timers. Even if the end DNS clients don’t support these timers, they will receive our new functionality via the DNS resolvers and recursive servers. In summary, our contributions give much more control to the organizations, as to under which specific conditions the DNS cache entries should be aged or used. This allows the organization to (1) much more quickly expire client DNS caches and (2) to mitigate the DDoS DNS attack effects. Our contributions are also helpful to organizations, even if there are no DDoS DNS attack.

  • 48.
    Booth, Todd
    et al.
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Computer Science.
    Andersson, Karl
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Computer Science. Luleå University of Technology, Centre for Critical Infrastructure and Societal Security.
    Stronger Authentication for Password Credential Internet Services2017In: Proceedings of the 2017 Third Conference on Mobile and Secure Services (MOBISECSERV) / [ed] Pascal Urien, Selwyn Piramuthu, Piscataway, NJ: IEEE conference proceedings, 2017, 41-45 p., 7886566Conference paper (Refereed)
    Abstract [en]

    Most Web and other on-line service providers (”Inter- net Services”) only support legacy ID (or email) and password (ID/PW) credential authentication. However, there are numerous vulnerabilities concerning ID/PW credentials. Scholars and the industry have proposed several improved security solutions, such as MFA, however most of the Internet Services have refused to adopt these solutions. Mobile phones are much more sensitive to these vulnerabilities (so this paper focuses on mobile phones). Many users take advantage of password managers, to keep track of all their Internet Service profiles. However, the Internet Service profiles found in password managers, are normally kept on the PC or mobile phone’s disk, in an encrypted form. Our first contribution is a design guideline, whereby the Internet Service profiles never need to touch the client’s disk. Most users would benefit, if they had the ability to use MFA, to login to a legacy Internet Service, which only supports ID/PW credential authentication. Our second contribution is a design guideline, whereby users can choose, for each legacy ID/PW Internet Service, which specific MFA they wish to use. We have also presenting conceptual design guidelines, showing that both of our contributions are minor changes to existing password managers, which can be implemented easily with low overhead.

  • 49.
    Borg, Niklas
    et al.
    Telia Research AB.
    Svanberg, Emil
    Telia Research AB.
    Schelén, Olov
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Computer Science.
    Efficient multi-field packet classification for QoS purposes1999In: 1999 Seventh International Workshop on Quality of Service: IWQoS '99, London, England, May 31 - June 4, 1999, Piscataway, NJ: IEEE Communications Society, 1999, 109-118 p.Conference paper (Refereed)
    Abstract [en]

    Mechanisms for service differentiation in datagram networks, such as the Internet, rely on packet classification in routers to provide appropriate service. Classification involves matching multiple packet header fields against a possibly large set of filters identifying the different service classes. In this paper, we describe a packet classifier based on tries and binomial trees and we investigate its scaling properties in three QoS scenarios that are likely to occur in the Internet. One scenario is based on integrated services and RSVP and the other two are based on differentiated services. By performing a series of tests, we characterize the processing and memory requirements for a software implementation of our classifier. Evaluation is done using real data sets taken from two existing high-speed networks. Results from the IntServ/RSVP tests on a Pentium 200 MHz show that it takes about 10.5 μs per packet and requires 2000 KBytes of memory to classify among 11000 entries. Classification for a virtual leased line service based on DiffServ with the same number of entries takes about 9 μs per packet and uses less than 250 KBytes of memory. With an average packet size of 2000 bits, our classifier can manage data rates of about 200 Mbit/s on a 200 MHz Pentium. We conclude that multi-field classification is feasible in software and that high-performance classifiers can run on low-cost hardware

  • 50.
    Bose, P.
    et al.
    School of Computer Science, Carleton University, Ottawa.
    Brodnik, Andrej
    Carlsson, S.
    University of Karlskona/Ronneby.
    Demaine, E.D.
    Massachusetts Institute of Technology, Laboratory for Computer Science, Cambridge.
    Fleischer, R.
    Department of Computer Science, Hong Kong University of Science and Technology.
    López-Ortiz, A.
    Department of Computer Science, University of Waterloo, Ontario.
    Morin, P.
    School of Computer Science, Carleton University, Ottawa.
    Munro, J.I.
    Department of Computer Science, University of Waterloo, Ontario.
    Online routing in convex subdivisions2002In: International journal of computational geometry and applications, ISSN 0218-1959, Vol. 12, no 4, 283-295 p.Article in journal (Refereed)
    Abstract [en]

    We consider online routing algorithms for finding paths between the vertices of plane graphs. We show (1) there exists a routing algorithm for arbitrary triangulations that has no memory and uses no randomization, (2) no equivalent result is possible for convex subdivisions, (3) there is no competitive online routing algorithm under the Euclidean distance metric in arbitrary triangulations, and (4) there is no competitive online routing algorithm under the link distance metric even when the input graph is restricted to be a Delaunay, greedy, or minimum-weight triangulation

1234567 1 - 50 of 478
CiteExportLink to result list
Permanent link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf