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  • 101.
    Araujo, Hugo
    et al.
    Universidade Federal de Pernambuco, Recife, PE, Brazil.
    Carvalho, Gustavo
    Universidade Federal de Pernambuco, Recife, PE, Brazil.
    Sampaio, Augusto
    Universidade Federal de Pernambuco, Recife, PE, Brazil.
    Mousavi, Mohammad Reza
    Halmstad University, School of Information Technology, Halmstad Embedded and Intelligent Systems Research (EIS), Centre for Research on Embedded Systems (CERES).
    Taromirad, Masoumeh
    Halmstad University, School of Information Technology, Halmstad Embedded and Intelligent Systems Research (EIS).
    A Process for Sound Conformance Testing of Cyber-Physical Systems2017In: 2017 IEEE International Conference on Software Testing, Verification and Validation Workshops (ICSTW) / [ed] Randall Bilof, Los Alamitos, CA: IEEE Computer Society, 2017, p. 46-50, article id 7899032Conference paper (Refereed)
    Abstract [en]

    We present a process for sound conformance testing of cyber-physical systems, which involves functional but also non-functional aspects. The process starts with a hybrid model of cyber-physical systems in which the correct behavior of the system (at its interface level) is specified. Such a model captures both discrete behavior and evolution of continuous dynamics of the system in time. Since conformance testing inherently involves comparing continuous dynamics, the key parameters of the process are (1) the conformance bounds defining when two signals are sufficiently close to each other, and (2) the permitted error margin in the conformance analysis introduced by sampling of continuous signals. The final parameter of this process is (3) finding (and adjusting) the sampling rate of the dynamic behavior. In the specified process, we provide different alternatives for fixing the error margin of the conformance testing if the sampling rate is fixed, establishing the sampling rate if the error margin is fixed and finding conformance bounds once the sampling rate and the error margin are fixed. © 2017 IEEE.

  • 102.
    Arts, Thomas
    et al.
    Quviq AB, Gothenburg, Sweden.
    Mousavi, Mohammad Reza
    Halmstad University, School of Information Technology, Halmstad Embedded and Intelligent Systems Research (EIS), Centre for Research on Embedded Systems (CERES).
    Automatic Consequence Analysis of Automotive Standards (AUTO-CAAS) [Position Paper]2015In: WASA '15: Proceedings of the First International Workshop on Automotive Software Architecture / [ed] Yanja Dajsuren, Harald Altinger & Miroslaw Staron, New York, NY: ACM Press, 2015, p. 35-38Conference paper (Refereed)
    Abstract [en]

    This paper provides some background and the roadmap of the AUTO-CAAS project, which is a 3-year project financed by the Swedish Knowledge Foundation and is ongoing as a joint project among three academic and industrial partners. The aim of the project is to exploit the formal models of the AUTOSAR standard, developed by the industrial partner of the project Quviq AB, in order to predict possible future failures in concrete implementations of components. To this end, the deviations from the formal specification will be exploited to generate test-cases that can push concrete components to the corners where such deviation will result in observable failures. The same information will also be used in the diagnosis of otherwise detected failures in order to pinpoint their root causes.

  • 103.
    Arunesh, Sanjana
    et al.
    Halmstad University, School of Information Technology, Halmstad Embedded and Intelligent Systems Research (EIS).
    Padi Siva, Abhilash
    Halmstad University, School of Information Technology, Halmstad Embedded and Intelligent Systems Research (EIS).
    Robot Assisted Quiz Espying of Learner's: RAQUEL2018Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    As robot technologies develop, many researchers have tried to use robots to support education. Studies have shown that robots can help students develop problem-solving abilities. Robotics technology is being increasingly integrated into the field of education largely due to the appealing image of robot’s young students have. With the rapid development of robotics, it has become feasible to use an educational robot for enhancing learning. This thesis explores the possibility of using robots as an educational tool for being quiz assistant in the class. Here we will be working with the humanoid-like robot and we will teach the robot to be a quiz assistant. The main purpose of this thesis is to have quizzes adapted to an individual knowledge of students in the class. By doing this a teacher can track a student’s performance individually while students will get the performance results as feedback using paper quizzes. When implemented fully, quizzes will be printed, distributed to students, collected from them, corrected, and students will be individually informed by email automatically and rapidly. Conceptually, this is a new approach to learning since frequent, paper-based quizzes become a learning tool in the service of active learning as opposed to their classical use, infrequently used control tool. The thesis scope is limited to contribute to individualization, distribution, and collection of the quizzes, leaving out the automatic correction. This is because for the latter there are already implemented solutions. With individualization, we mean identification of a student taking a certain quiz and conversely, deducing the identity of a student from a collected quiz. For this, we will use face detection and face recognition techniques. To this effect, an algorithm based on the technique Haar cascade by Viola and Jones [1]was used for face detection and Local Binary Pattern Histogram [from now on calledLBPH] method was used for face recognition [2]. This combination is shown to be, precise and maximally avoids illumination problems. The thesis also marks important details missing in the aforementioned paper as well as some drawbacks of the proposed technique. Our results show that RAQUEL system can perform face detection and recognition effectively by identifying and depending on the chosen interfacing strategy, then voicing identification details such as names, individual quiz number and seating row number of the students. Our system can not only be used to identify and bind a student identity to a certain quiz number, but also it can detail class/quiz attendance and keep track of in what order students gave back the quiz papers, helping to assure by biometric identification, that the automatically corrected quiz results are registered for correct student identity.

  • 104.
    Arvidsson, Fredrik
    et al.
    Department of Computer and Information Science, Linköping University.
    Ihlström, Carina
    Halmstad University, School of Information Science, Computer and Electrical Engineering (IDE), Halmstad Embedded and Intelligent Systems Research (EIS).
    Lundberg, Jonas
    Department of Computer and Information Science, Linköping University.
    Visions of Future News - Consensus or Conflict?2002In: Proceedings of the 25th Information Systems Research Seminar in Scandinavia (IRIS), IRIS , 2002, p. 25-Conference paper (Refereed)
    Abstract [en]

    The move from print to multimedia will cause changes not only to the form of the news service but also the involved processes in the news organizations. The cooperative scenario building technique is used on a number of groups; end-users, management and media professionals to envisioning the news services of the future. We take the perspective of consensus and conflict to illustrate the identified visions. Firstly, we illuminate conflicts and consensus between the groups, regarding their visions and future use scenarios. Secondly, we show the implications of using the cooperative scenariobuilding technique in relation the consensus and conflict perspectives in cooperative design. We conclude that both consensus and conflicts could be found in the scenarios described in the paper and that the cooperative technique was suitable in this context.

  • 105.
    Ashfaq, Awais
    Halmstad University, School of Information Technology, Halmstad Embedded and Intelligent Systems Research (EIS), CAISR - Center for Applied Intelligent Systems Research.
    Predicting clinical outcomes via machine learning on electronic health records2019Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    The rising complexity in healthcare, exacerbated by an ageing population, results in ineffective decision-making leading to detrimental effects on care quality and escalates care costs. Consequently, there is a need for smart decision support systems that can empower clinician's to make better informed care decisions. Decisions, which are not only based on general clinical knowledge and personal experience, but also rest on personalised and precise insights about future patient outcomes. A promising approach is to leverage the ongoing digitization of healthcare that generates unprecedented amounts of clinical data stored in Electronic Health Records (EHRs) and couple it with modern Machine Learning (ML) toolset for clinical decision support, and simultaneously, expand the evidence base of medicine. As promising as it sounds, assimilating complete clinical data that provides a rich perspective of the patient's health state comes with a multitude of data-science challenges that impede efficient learning of ML models. This thesis primarily focuses on learning comprehensive patient representations from EHRs. The key challenges of heterogeneity and temporality in EHR data are addressed using human-derived features appended to contextual embeddings of clinical concepts and Long-Short-Term-Memory networks, respectively. The developed models are empirically evaluated in the context of predicting adverse clinical outcomes such as mortality or hospital readmissions. We also present evidence that, surprisingly, different ML models primarily designed for non-EHR analysis (like language processing and time-series prediction) can be combined and adapted into a single framework to efficiently represent EHR data and predict patient outcomes.

  • 106.
    Ashfaq, Awais
    et al.
    Halmstad University, School of Information Technology, Halmstad Embedded and Intelligent Systems Research (EIS), CAISR - Center for Applied Intelligent Systems Research. KTH Royal Institute of Technology, Stockholm, Sweden.
    Adler, Jonas
    KTH Royal Institute of Technology, Stockholm, Sweden & Elekta Instrument AB, Stockholm, Sweden.
    A modified fuzzy C means algorithm for shading correction in craniofacial CBCT images2017In: CMBEBIH 2017: Proceedings of the International Conference on Medical and Biological Engineering 2017 / [ed] Almir Badnjevic, Singapore: Springer, 2017, Vol. 62, p. 531-538Conference paper (Refereed)
    Abstract [en]

    CBCT images suffer from acute shading artifacts primarily due to scatter. Numerous image-domain correction algorithms have been proposed in the literature that use patient-specific planning CT images to estimate shading contributions in CBCT images. However, in the context of radiosurgery applications such as gamma knife, planning images are often acquired through MRI which impedes the use of polynomial fitting approaches for shading correction. We present a new shading correction approach that is independent of planning CT images. Our algorithm is based on the assumption that true CBCT images follow a uniform volumetric intensity distribution per material, and scatter perturbs this uniform texture by contributing cupping and shading artifacts in the image domain. The framework is a combination of fuzzy C-means coupled with a neighborhood regularization term and Otsu’s method. Experimental results on artificially simulated craniofacial CBCT images are provided to demonstrate the effectiveness of our algorithm. Spatial non-uniformity is reduced from 16% to 7% in soft tissue and from 44% to 8% in bone regions. With shading-correction, thresholding based segmentation accuracy for bone pixels is improved from 85% to 91% when compared to thresholding without shading-correction. The proposed algorithm is thus practical and qualifies as a plug and play extension into any CBCT reconstruction software for shading correction. © Springer Nature Singapore Pte Ltd. 2017.

  • 107.
    Ashfaq, Awais
    et al.
    Halmstad University, School of Information Technology, Halmstad Embedded and Intelligent Systems Research (EIS), CAISR - Center for Applied Intelligent Systems Research.
    Lönn, Stefan
    Research and Development, Region Halland, Sweden.
    Nilsson, Håkan
    Economic Department, Region Halland, Sweden.
    Eriksson, Jonny
    Halland Hospital, Region Halland, Sweden.
    Kwatra, Japneet
    Brigham and Women’s Hospital, US.
    Yasin, Zayed
    Brigham and Women’s Hospital, US.
    Slutzman, Jonathan
    Massachusetts General Hospital, US.
    Wallenfeldt, Thomas
    CGI Group Inc. Consultants to Government and Industries, Sweden.
    Obermeyer, Ziad
    School of Public Health, University of California at Berkeley, US.
    Anderson, Philip
    Department of Emergency Medicine, Brigham & Women’s Hospital, Harvard Medical School, Boston, US..
    Lingman, Markus
    Halland Hospital, Region Halland, Sweden.
    Data Profile: Regional Healthcare Information Platform in Halland, Sweden2019In: International Journal of Epidemiology, ISSN 0300-5771, E-ISSN 1464-3685Article in journal (Refereed)
    Abstract [en]

    Accurate and comprehensive healthcare data coupled with modern analytical tools can play a vital role in enabling care providers to make better-informed decisions, leading to effective and cost-efficient care delivery. This paper describes a novel strategic healthcare analysis and research platform that encapsulates 360-degree pseudo-anonymized data covering clinical, operational capacity and financial data on over 500,000 patients treated since 2009 across all care delivery units in the county of Halland, Sweden. The over-arching goal is to develop a comprehensive healthcare data infrastructure that captures complete care processes at individual, organizational and population levels. These longitudinal linked healthcare data are a valuable tool for research in a broad range of areas including health economy and process development using real world evidence.

    Key messages

    Structured and standardized variables have been linked from different regional healthcare sources into a research information platform including all healthcare visits in the county of Halland in Sweden, from 2009 to date.

    Since 2015, the regional information platform integrates a cost component to each healthcare visit: thus being able to quantify patient level value, safety and cost efficiency across the continuum of care.

  • 108.
    Ashfaq, Awais
    et al.
    Halmstad University, School of Information Technology, Halmstad Embedded and Intelligent Systems Research (EIS), CAISR - Center for Applied Intelligent Systems Research. Halland Hospital, Region Halland, Halmstad, Sweden.
    Nowaczyk, Sławomir
    Halmstad University, School of Information Technology, Halmstad Embedded and Intelligent Systems Research (EIS), CAISR - Center for Applied Intelligent Systems Research.
    Machine learning in healthcare - a system’s perspective2019In: Proceedings of the ACM SIGKDD Workshop on Epidemiology meets Data Mining and Knowledge Discovery (epiDAMIK) / [ed] B. Aditya Prakash, Anil Vullikanti, Shweta Bansal, Adam Sadelik, Arlington, 2019, p. 14-17Conference paper (Refereed)
    Abstract [en]

    A consequence of the fragmented and siloed healthcare landscape is that patient care (and data) is split along multitude of different facilities and computer systems and enabling interoperability between these systems is hard. The lack interoperability not only hinders continuity of care and burdens providers, but also hinders effective application of Machine Learning (ML) algorithms. Thus, most current ML algorithms, designed to understand patient care and facilitate clinical decision-support, are trained on limited datasets. This approach is analogous to the Newtonian paradigm of Reductionism in which a system is broken down into elementary components and a description of the whole is formed by understanding those components individually. A key limitation of the reductionist approach is that it ignores the component-component interactions and dynamics within the system which are often of prime significance in understanding the overall behaviour of complex adaptive systems (CAS). Healthcare is a CAS.

    Though the application of ML on health data have shown incremental improvements for clinical decision support, ML has a much a broader potential to restructure care delivery as a whole and maximize care value. However, this ML potential remains largely untapped: primarily due to functional limitations of Electronic Health Records (EHR) and the inability to see the healthcare system as a whole. This viewpoint (i) articulates the healthcare as a complex system which has a biological and an organizational perspective, (ii) motivates with examples, the need of a system's approach when addressing healthcare challenges via ML and, (iii) emphasizes to unleash EHR functionality - while duly respecting all ethical and legal concerns - to reap full benefits of ML.

  • 109.
    Ashfaq, Awais
    et al.
    Halmstad University, School of Information Technology, Halmstad Embedded and Intelligent Systems Research (EIS), CAISR - Center for Applied Intelligent Systems Research. Halland Hospital, Region Halland, Sweden.
    Pinheiro Sant'Anna, Anita
    Halmstad University, School of Information Technology, Halmstad Embedded and Intelligent Systems Research (EIS), CAISR - Center for Applied Intelligent Systems Research.
    Lingman, Markus
    Halland Hospital, Region Halland, Sweden & Institute of Medicine, Dept. of Molecular and Clinical Medicine/Cardiology, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden.
    Nowaczyk, Sławomir
    Halmstad University, School of Information Technology, Halmstad Embedded and Intelligent Systems Research (EIS), CAISR - Center for Applied Intelligent Systems Research.
    Readmission prediction using deep learning on electronic health records2019In: Journal of Biomedical Informatics, ISSN 1532-0464, E-ISSN 1532-0480, Vol. 97, article id 103256Article in journal (Refereed)
    Abstract [en]

    Unscheduled 30-day readmissions are a hallmark of Congestive Heart Failure (CHF) patients that pose significant health risks and escalate care cost. In order to reduce readmissions and curb the cost of care, it is important to initiate targeted intervention programs for patients at risk of readmission. This requires identifying high-risk patients at the time of discharge from hospital. Here, using real data from over 7,500 CHF patients hospitalized between 2012 and 2016 in Sweden, we built and tested a deep learning framework to predict 30-day unscheduled readmission. We present a cost-sensitive formulation of Long Short-Term Memory (LSTM) neural network using expert features and contextual embedding of clinical concepts. This study targets key elements of an Electronic Health Record (EHR) driven prediction model in a single framework: using both expert and machine derived features, incorporating sequential patterns and addressing the class imbalance problem. We show that the model with all key elements achieves a higher discrimination ability (AUC 0.77) compared to the rest. Additionally, we present a simple financial analysis to estimate annual savings if targeted interventions are offered to high risk patients. © 2019 The Authors

  • 110.
    Assabie Lake, Yaregal
    Halmstad University, School of Information Science, Computer and Electrical Engineering (IDE), Halmstad Embedded and Intelligent Systems Research (EIS).
    Multifont recognition System for Ethiopic Script2006Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    In this thesis, we present a general framework for multi-font, multi-size and multi-style Ethiopic character recognition system. We propose structural and syntactic techniques for recognition of Ethiopic characters where the graphically comnplex characters are represented by less complex primitive structures and their spatial interrelationships. For each Ethiopic character, the primitive structures and their spatial interrelationships form a unique set of patterns.

    The interrelationships of primitives are represented by a special tree structure which resembles a binary search tree in the sense that it groups child nodes as left and right, and keeps the spatial position of primitives in orderly manner. For a better computational efficiency, the primitive tree is converted into string pattern using in-order traversal, which generates a base of the alphabet that stores possibly occuring string patterns for each character. The recognition of characters is then achieved by matching the generated patterns with each pattern in a stored knowledge base of characters.

    Structural features are extracted using direction field tensor, which is also used for character segmentation. In general, the recognition system does not need size normalization, thinning or other preprocessing procedures. The only parameter that needs to be adjusted during the recognition process is the size of Gaussian window which should be chosen optimally in relation to font sizes. We also constructed an Ethiopic Document Image Database (EDIDB) from real life documents and the recognition system is tested with respect to variations in font type, size, style, document skewness and document type. Experimental results are reported.

  • 111.
    Assabie, Yaregal
    et al.
    Halmstad University, School of Information Science, Computer and Electrical Engineering (IDE), Halmstad Embedded and Intelligent Systems Research (EIS).
    Bigun, Josef
    Halmstad University, School of Information Science, Computer and Electrical Engineering (IDE), Halmstad Embedded and Intelligent Systems Research (EIS).
    A comprehensive Dataset for Ethiopic Handwriting Recognition2009In: Proceedings SSBA '09: Symposium on Image Analysis, Halmstad University, Halmstad, March 18-20, 2009 / [ed] Josef Bigun & Antanas Verikas, Halmstad: Halmstad University , 2009, p. 41-43Chapter in book (Other academic)
    Abstract [en]

    Ethiopic script is used by several languages in Ethiopia for writing. We present a comprehensive dataset of handwritten Ethiopic script called DEHR (Dataset for Ethiopic Handwriting Recognition) captured both offline and online. The offline dataset includes isolated characters, Ethiopian church documents and ordinary handwritten texts dealing with various real-life issues. The ordinary texts and isolated characters were freely written by several participants. The church documents are written in Geez and Amharic languages whereas the language for ordinary texts is Amharic only. The online dataset was collected by using two Digimemo devices of different sizes. For isolated characters and online dataset, all the 265 character samples used by Amharic language are included. The dataset is intended to set a benchmark for training and/or testing handwriting recognition, character and word segmentation, and text line detection. The dataset is can be accessed by contacting the authors or via http://www.hh.se/staff/josef/.

  • 112.
    Assabie, Yaregal
    et al.
    Addis Ababa University, Department of Computer Science, Addis Ababa, Ethiopia .
    Bigun, Josef
    Halmstad University, School of Information Technology, Halmstad Embedded and Intelligent Systems Research (EIS), Intelligent systems (IS-lab).
    A Hybrid System for Robust Recognition of Ethiopic Script2007In: Ninth International Conference on Document Analysis and Recognition: proceedings : Curtiba, Paraná, Brazil, September 23-26, 2007 / [ed] IEEE Computer Society, Los Alamitos, Calif.: IEEE Computer Society, 2007, p. 556-560Conference paper (Refereed)
    Abstract [en]

    In real life, documents contain several font types, styles, and sizes. However, many character recognition systems show good results for specific type of documents and fail to produce satisfactory results for others. Over the past decades, various pattern recognition techniques have been applied with the aim to develop recognition systems insensitive to variations in the characteristics of documents. In this paper, we present a robust recognition system for Ethiopic script using a hybrid of classifiers. The complex structures of Ethiopic characters are structurally and syntactically analyzed, and represented as a pattern of simpler graphical units called primitives. The pattern is used for classification of characters using similarity-based matching and neural network classifier. The classification result is further refined by using template matching. A pair of directional filters is used for creating templates and extracting structural features. The recognition system is tested by real life documents and experimental results are reported.

  • 113.
    Assabie, Yaregal
    et al.
    Halmstad University, School of Information Science, Computer and Electrical Engineering (IDE), Halmstad Embedded and Intelligent Systems Research (EIS).
    Bigun, Josef
    Halmstad University, School of Information Science, Computer and Electrical Engineering (IDE), Halmstad Embedded and Intelligent Systems Research (EIS).
    A neural network approach for multifont and size-independent recognition of ethiopic characters2007In: Progress in pattern recognition / [ed] Singh, S, Singh, M, Springer London, 2007, p. 129-137Conference paper (Refereed)
    Abstract [en]

    Artificial neural networks are one of the most commonly used tools for character recognition problems, and usually they take gray values of 2D character images as inputs. In this paper, we propose a novel neural network classifier whose input is ID string patterns generated from the spatial relationships of primitive structures of Ethiopiccharacters. The spatial relationships of primitives are modeled by a special tree structure from which a unique set of string patterns are generated for each character. Training theneural network with string patterns of different font types and styles enables the classifier to handle variations in font types, sizes, and styles. We use a pair of directional filters forextracting primitives and their spatial relationships. The robustness of the proposed recognition system is tested by real life documents and experimental results are reported.

  • 114.
    Assabie, Yaregal
    et al.
    Addis Ababa University, Department of Computer Science, Addis Ababa, Ethiopia .
    Bigun, Josef
    Halmstad University, School of Information Technology, Halmstad Embedded and Intelligent Systems Research (EIS), Intelligent systems (IS-lab).
    Ethiopic Character Recognition Using Direction Field Tensor2006In: The 18th International Conference on Pattern Recognition: proceedings : 20-24 August, 2006, Hong Kong, Los Alamitos, Calif.: IEEE Computer Society, 2006, p. 284-287Conference paper (Refereed)
    Abstract [en]

    Many languages in Ethiopia use a unique alphabet called Ethiopic for writing. However, there is no OCR system developed to date. In an effort to develop automatic recognition of Ethiopic script, a novel system is designed by applying structural and syntactic techniques. The recognition system is developed by extracting primitive structural features and their spatial relationships. A special tree structure is used to represent the spatial relationship of primitive structures. For each character, a unique string pattern is generated from the tree and recognition is achieved by matching the string against a stored knowledge base of the alphabet. To implement the recognition system, we use direction field tensor as a tool for character segmentation, and extraction of structural features and their spatial relationships. Experimental results are reported.

  • 115.
    Assabie, Yaregal
    et al.
    Halmstad University, School of Information Science, Computer and Electrical Engineering (IDE), Halmstad Embedded and Intelligent Systems Research (EIS).
    Bigun, Josef
    Halmstad University, School of Information Science, Computer and Electrical Engineering (IDE), Halmstad Embedded and Intelligent Systems Research (EIS).
    Ethiopic Document Image Database for Testing Character Recognition Systems2006Report (Other academic)
    Abstract [en]

    In this paper we describe the acquisition and content of a large database of Ethiopic documents for testing and evaluating character recognition systems. The Ethiopic Document Image Database (EDIDB) contains documents written in Amharic and Geez languages. The database was built from a variety of documents such as printouts, books, newspapers, and magazines. Documents written in various font types, sizes and styles were included in the database. Degraded and poor quality documents were also included in the database to represent the real life situation. A total of 1,204 pages were scanned at a resolution of 300 dpi and saved as grayscale images of JPEG format. We also describe an evaluation protocol for standardizing the comparison of recognition systems and their results. The database is made available to the research community through http://www.hh.se/staff/josef/.

  • 116.
    Assabie, Yaregal
    et al.
    Addis Ababa University, Department of Computer Science, Addis Ababa Ethiopia.
    Bigun, Josef
    Halmstad University, School of Information Technology, Halmstad Embedded and Intelligent Systems Research (EIS), Intelligent systems (IS-lab).
    HMM-Based Handwritten Amharic Word Recognition with Feature Concatenation2009In: Proceedings of the International Conference on Document Analysis and Recognition, ICDAR, New York: IEEE Press, 2009, p. 961-965Conference paper (Refereed)
    Abstract [en]

    Amharic is the official language of Ethiopia and uses Ethiopic script for writing. In this paper, we present writer-independent HMM-based Amharic word recognition for offline handwritten text. The underlying units of the recognition system are a set of primitive strokes whose combinations form handwritten Ethiopic characters. For each character, possibly occurring sequences of primitive strokes and their spatial relationships, collectively termed as primitive structural features, are stored as feature list. Hidden Markov models for Amharic words are trained with such sequences of structural features of characters constituting words. The recognition phase does not require segmentation of characters but only requires text line detection and extraction of structural features in each text line. Text lines and primitive structural features are extracted by making use of direction field tensor. The performance of the recognition system is tested by a database of unconstrained handwritten documents collected from various sources.

  • 117.
    Assabie, Yaregal
    et al.
    Addis Ababa University, Department of Computer Science, Addis Ababa Ethiopia .
    Bigun, Josef
    Halmstad University, School of Information Technology, Halmstad Embedded and Intelligent Systems Research (EIS), Intelligent systems (IS-lab).
    Lexicon-based Offline Recognition of Amharic Words in Unconstrained Handwritten Text2008In: 19th International Conference on Pattern Recognition: (ICPR 2008) ; Tampa, Florida, USA 8-11 December 2008, New York: IEEE Computer Society, 2008, article id 4761145Conference paper (Refereed)
    Abstract [en]

    This paper describes an offline handwriting recognition system for Amharic words based on lexicon. The system computes direction fields of scanned handwritten documents, from which pseudo-characters are segmented. The pseudo-characters are organized based on their proximity and direction to form text lines. Words are then segmented by analyzing the relative gap between subsequent pseudocharacters in text lines. For each segmented word image, the structural characteristics of pseudo-characters are syntactically analyzed to predict a set of plausible characters forming the word. The most likelihood word is finally selected among candidates by matching against the lexicon. The system is tested by a database of unconstrained handwritten Amharic documents collected from various sources. The lexicon is prepared from words appearing in the collected database.

  • 118.
    Assabie, Yaregal
    et al.
    Addis Ababa University, Department of Computer Science, Addis Ababa, Ethiopia .
    Bigun, Josef
    Halmstad University, School of Information Technology, Halmstad Embedded and Intelligent Systems Research (EIS), Intelligent systems (IS-lab).
    Multifont size-resilient recognition system for Ethiopic script2007In: International Journal on Document Analysis and Recognition, ISSN 1433-2833, E-ISSN 1433-2825, Vol. 10, no 2, p. 85-100Article in journal (Refereed)
    Abstract [en]

    This paper presents a novel framework for recognition of Ethiopic characters using structural and syntactic techniques. Graphically complex characters are represented by the spatial relationships of less complex primitives which form a unique set of patterns for each character. The spatial relationship is represented by a special tree structure which is also used to generate string patterns of primitives. Recognition is then achieved by matching the generated string pattern against each pattern in the alphabet knowledge-base built for this purpose. The recognition system tolerates variations on the parameters of characters like font type, size and style. Direction field tensor is used as a tool to extract structural features.

  • 119.
    Assabie, Yaregal
    et al.
    Department of Computer Science, Addis Ababa University, Ethiopia.
    Bigun, Josef
    Halmstad University, School of Information Science, Computer and Electrical Engineering (IDE), Halmstad Embedded and Intelligent Systems Research (EIS), Intelligent Systems´ laboratory.
    Offline handwritten Amharic word recognition2011In: Pattern Recognition Letters, ISSN 0167-8655, E-ISSN 1872-7344, Vol. 32, no 8, p. 1089-1099Article in journal (Refereed)
    Abstract [en]

    This paper describes two approaches for Amharic word recognition in unconstrained handwritten text using HMMs. The first approach builds word models from concatenated features of constituent characters and in the second method HMMs of constituent characters are concatenated to form word model. In both cases, the features used for training and recognition are a set of primitive strokes and their spatial relationships. The recognition system does not require segmentation of characters but requires text line detection and extraction of structural features, which is done by making use of direction field tensor. The performance of the recognition system is tested by a dataset of unconstrained handwritten documents collected from various sources, and promising results are obtained. (C) 2011 Elsevier B.V. All rights reserved.

  • 120.
    Assabie, Yaregal
    et al.
    Halmstad University, School of Information Science, Computer and Electrical Engineering (IDE), Halmstad Embedded and Intelligent Systems Research (EIS).
    Bigun, Josef
    Halmstad University, School of Information Science, Computer and Electrical Engineering (IDE), Halmstad Embedded and Intelligent Systems Research (EIS).
    Offline Handwritten Amharic Word Recognition Using HMMs2009In: Proceedings SSBA '09: Symposium on Image Analysis, Halmstad University, Halmstad, March 18-20, 2009 / [ed] Josef Bigun & Antanas Verikas, Halmstad: Halmstad University , 2009, p. 89-92Chapter in book (Other academic)
    Abstract [en]

    This paper describes two appraches for Amharic word recognition in unconstrained handwritten text using HMMs. The first approach builds word models from concatenated features of constituent characters and in the second method HMMs of constituent characters are concatenated to form word model. In both cases, the features used for training and recognition are primitive strokes and their spatial relationships. The recognition system does not require segmentation of characters but requires text line detection and extraction of structural features, which is done by making use of direction field tensor. The performance of the recognition system is tested by DEHR dataset of unconstrained handwritten documents collected from various sources.

  • 121.
    Assabie, Yaregal
    et al.
    Addis Ababa University, Department of Computer Science, Addis Ababa, Ethiopia.
    Bigun, Josef
    Halmstad University, School of Information Technology, Halmstad Embedded and Intelligent Systems Research (EIS), Intelligent systems (IS-lab).
    Online Handwriting Recognition of Ethiopic Script2008In: Proceedings: Eleventh International Conference on Frontiers in Handwriting Recognition, Montréal, Québec - Canada, August 19-21, 2008 / [ed] Ching Y Suen, Montréal: CENPARMI, Concordia University , 2008, p. 153-158Conference paper (Refereed)
    Abstract [en]

    Online recognition of handwritten characters is gaining a renewed interest as it provides a natural way of data entry for a wide variety of handheld devices. In this paper, we present online handwriting recognition system for Ethiopic script based on the structural and syntactical analysis of the strokes forming characters. The complex structures of characters are represented by the spatio- temporal relationships of simple-shaped strokes called primitives. A special tree structure is used to model spatio- temporal relationships of the strokes. The tree generates a unique set of primitive stroke sequences for each character, and for recognition each stroke sequence is matched against a stored knowledge base. Characters are also classified based on their structural similarity to select a plausible set of characters for un unknown input, which improves recognition and processing time. We also present a dataset collected for training and testing online recognition systems for Ethiopic script. The dataset is prepared in accordance with the international standard UNIPEN format. The recognition system is tested with the collected dataset and experimental results are reported.

  • 122.
    Assabie, Yaregal
    et al.
    Addis Ababa University, Department of Computer Science, Addis Ababa, Ethiopia .
    Bigun, Josef
    Halmstad University, School of Information Technology, Halmstad Embedded and Intelligent Systems Research (EIS), Intelligent systems (IS-lab).
    Structural and Syntactic Techniques for Recognition of Ethiopic Characters2006In: Structural, syntactic, and statistical pattern recognition joint IAPR international workshops SSPR 2006 and SPR 2006, Hong Kong, China, August 17-19, 2006 : proceedings: Lecture Notes in Computer Sciences (Volume 4109/2006), Berlin: Springer Berlin/Heidelberg, 2006, p. 118-126Conference paper (Refereed)
    Abstract [en]

    OCR technology of Latin scripts is well advanced in comparison to other scripts. However, the available results from Latin are not always sufficient to directly adopt them for other scripts such as the Ethiopic script. In this paper, we propose a novel approach that uses structural and syntactic techniques for recognition of Ethiopic characters. We reveal that primitive structures and their spatial relationships form a unique set of patterns for each character. The relationships of primitives are represented by a special tree structure, which is also used to generate a pattern. A knowledge base of the alphabet that stores possibly occurring patterns for each character is built. Recognition is then achieved by matching the generated pattern against each pattern in the knowledge base. Structural features are extracted using direction field tensor. Experimental results are reported, and the recognition system is insensitive to variations on font types, sizes and styles.

  • 123.
    Assabie, Yaregal
    et al.
    Addis Ababa University, Department of Computer Science, Addis Ababa Ethiopia.
    Bigun, Josef
    Halmstad University, School of Information Technology, Halmstad Embedded and Intelligent Systems Research (EIS).
    Writer-independent Offline Recognition of Handwritten Ethiopic Characters2008In: Proceedings: Eleventh International Conference on Frontiers in Handwriting Recognition, Montréal, Québec - Canada, August 19-21, 2008 / [ed] Ching Y Suen, Montréal: CENPARMI, Concordia University , 2008, p. 652-657Conference paper (Refereed)
    Abstract [en]

    This paper presents writer-independent offline handwritten character recognition for Ethiopic script. The recognition is based on the characteristics of primitive strokes that make up characters. The spatial relationships of primitives whose combinations form complex structures of Ethiopic characters are used as a basis for recognition. Although this approach efficiently recognizes properly written characters, the recognition rate drops for characters where the spatial relationships of their primitives could not be drawn. This happens mostly when the connections between primitives are not properly written, which is a common case in handwriting. To complement the recognition, we classify characters based on the characteristics of their primitives, resulting in grouping of characters in a five-dimensional space. Once the type of characters is identified, recognition can be achieved with a minimal set of information from their spatial relationships. A comprehensive database is also developed to standardize the evaluation of research works on offline Ethiopic handwriting recognition systems. Our proposed system is tested is with the database and experimental results are reported.

  • 124.
    Aujla, Gagangeet Singh
    et al.
    Thapar University, Patiala, India.
    Chaudhary, Rajat
    Thapar University, Patiala, India.
    Kumar, Neeraj
    Thapar University, Patiala, India.
    Rodrigues, Joel J. P. C.
    National Institute of Telecommunications (Inatel), Santa Rita do Sapucaí, Brazil; University of Beira Interior, Covilhã, Portugal; ITMO University, St. Petersburg, Russia; University of Fortaleza (Unifor), Fortaleza, Brazil.
    Vinel, Alexey
    Halmstad University, School of Information Technology, Halmstad Embedded and Intelligent Systems Research (EIS), Centre for Research on Embedded Systems (CERES).
    Data Offloading in 5G-Enabled Software-Defined Vehicular Networks: A Stackelberg-Game-Based Approach2017In: IEEE Communications Magazine, ISSN 0163-6804, E-ISSN 1558-1896, Vol. 55, no 8, p. 100-108Article in journal (Refereed)
    Abstract [en]

    Data offloading using vehicles is one of the most challenging tasks to perform due to the high mobility of vehicles. There are many solutions available for this purpose, but due to the inefficient management of data along with the control decisions, these solutions are not adequate to provide data offloading by making use of the available networks. Moreover, with the advent of 5G and related technologies, there is a need to cope with high speed and traffic congestion in the existing infrastructure used for data offloading. Hence, to make intelligent decisions for data offloading, an SDN-based scheme is presented in this article. In the proposed scheme, an SDNbased controller is designed that makes decisions for data offloading by using the priority manager and load balancer. Using these two managers in SDN-based controllers, traffic routing is managed efficiently even with an increase in the size of the network. Moreover, a single-leader multi-follower Stackelberg game for network selection is also used for data offloading. The proposed scheme is evaluated with respect to several parameters where its performance was found to be superior in comparison to the existing schemes. © Copyright 2017 IEEE

  • 125.
    Babich, M. V.
    et al.
    St. Petersburg Department of Steklov Mathematical Institute .
    Bordag, Ljudmila A.
    Halmstad University, School of Information Science, Computer and Electrical Engineering (IDE), Halmstad Embedded and Intelligent Systems Research (EIS), Applied Mathematics and Physics (CAMP).
    Quasi periodic vortex structures in two-dimensional flows in an inviscid incompressible fluid2005In: Russian journal of mathematical physics, ISSN 1061-9208, E-ISSN 1555-6638, Vol. 12, no 2, p. 121-156Article in journal (Refereed)
    Abstract [en]

    We consider a two-dimensional steady motion of an inviscid incompressible fluid described by the equation &UDelta; u(x,y) = F(u(x,y)), where u(x,y) is the streamfunction, &UDelta; is the Laplace operator, and F((.)) an arbitrary function measuring the flow vorticity. Apparently, until now, the only way to treat an equation of the above type with nontrivial function F analytically is to use the algebro-geometric method for integrable equations. In particular, we investigate the Cosh-Laplace equation (ChL) &UDelta; u(x,y) = ± 4cosh(u(x,y)) by means of the special technique of finite-gap integration, which allows us to obtain real solutions of the ChL equation by using a Riemann surface with appropriate symmetry. We study the first nontrivial case corresponding to a Riemann surface of genus g = 3. The hydrodynamical interpretation of finite-gap solutions is meaningful, and we try to understand the fluid processes described by these solutions. To this end, we take a Riemann surface with additional symmetry properties. We present four five-parameter families of exact solutions. These solutions are given in terms of Jacobi elliptic functions, which enables us to directly investigate the relevant properties. We also find explicit formulas for the lines of singularity. It is of interest from the point of view of algebraic geometry that the structure of the theta divisor can be described.

  • 126.
    Bacauskiene, Marija
    et al.
    Department of Applied Electronics, Kaunas University of Technology, Studentu 50, LT-51368, Kaunas, Lithuania.
    Cibulskis, Vladas
    Department of Applied Electronics, Kaunas University of Technology, Studentu 50, LT-51368, Kaunas, Lithuania.
    Verikas, Antanas
    Halmstad University, School of Information Science, Computer and Electrical Engineering (IDE), Halmstad Embedded and Intelligent Systems Research (EIS), Intelligent systems (IS-lab).
    Selecting variables for neural network committees2006In: Advances in neural networks - ISNN 2006: third International Symposium on Neural Networks, Chengdu, China, May 28 - June 1, 2006 ; proceedings. I / [ed] Jun Wang, Berlin: Springer Berlin/Heidelberg, 2006, p. 837-842Conference paper (Refereed)
    Abstract [en]

    The aim of the variable selection is threefold: to reduce model complexity, to promote diversity of committee networks, and to find a trade-off between the accuracy and diversity of the networks. To achieve the goal, the steps of neural network training, aggregation, and elimination of irrelevant input variables are integrated based on the negative correlation learning [1] error function. Experimental tests performed on three real world problems have shown that statistically significant improvements in classification performance can be achieved from neural network committees trained according to the technique proposed.

  • 127.
    Bacauskiene, Marija
    et al.
    Kaunas University of Technology.
    Gelzinis, Adas
    Kaunas University of Technology.
    Kaseta, Marius
    Kaunas University of Medicine.
    Kovalenko, Marina
    Kaunas University of Technology.
    Pribuisiene, Ruta
    Kaunas University of Medicine.
    Uloza, Virgilijus
    Kaunas University of Medicine.
    Verikas, Antanas
    Halmstad University, School of Information Science, Computer and Electrical Engineering (IDE), Halmstad Embedded and Intelligent Systems Research (EIS), Intelligent systems (IS-lab).
    Multiple feature sets and genetic search based discrimination of pathological voices2007In: Proceedings of the International ConferenceModels and Analysis of Vocal Emissions for Biomedical Applications”, MAVEBA, 2007, p. 195-198Conference paper (Refereed)
  • 128.
    Bacauskiene, Marija
    et al.
    Department of Applied Electronics, Kaunas University of Technology LT-3031, Kaunas, Lithuania.
    Verikas, Antanas
    Halmstad University, School of Information Science, Computer and Electrical Engineering (IDE), Halmstad Embedded and Intelligent Systems Research (EIS).
    Selecting salient features for classification based on neural network committees2004In: Pattern Recognition Letters, ISSN 0167-8655, E-ISSN 1872-7344, Vol. 25, no 16, p. 1879-1891Article in journal (Refereed)
    Abstract [en]

    Aggregating outputs of multiple classifiers into a committee decision is one of the most important techniques for improving classification accuracy. The issue of selecting an optimal subset of relevant features plays also an important role in successful design of a pattern recognition system. In this paper, we present a neural network based approach for identifying salient features for classification in neural network committees. Feature selection is based on two criteria, namely the reaction of the cross-validation data set classification error due to the removal of the individual features and the diversity of neural networks comprising the committee. The algorithm developed removed a large number of features from the original data sets without reducing the classification accuracy of the committees. The accuracy of the committees utilizing the reduced feature sets was higher than those exploiting all the original features.

  • 129.
    Bacauskiene, Marija
    et al.
    Department of Applied Electronics, Kaunas University of Technology, LT-3031, Kaunas, Lithuania.
    Verikas, Antanas
    Halmstad University, School of Information Science, Computer and Electrical Engineering (IDE), Halmstad Embedded and Intelligent Systems Research (EIS).
    The Evidence Theory Based Post-Processing of Colour Images2004In: Informatica (Vilnius), ISSN 0868-4952, E-ISSN 1822-8844, Vol. 15, no 3, p. 315-328Article in journal (Refereed)
    Abstract [en]

    The problem of post-processing of a classified image is addressed from the point of view of the Dempster-Shafer theory of evidence. Each neighbour of a pixel being analyzed is considered as an item of evidence supporting particular hypotheses regarding the class label of that pixel. The strength of support is defined as a function of the degree of uncertainty in class label of the neighbour, and the distance between the neighbour and the pixel being considered. A post-processing window defines the neighbours. Basic belief masses are obtained for each of the neighbours and aggregated according to the rule of orthogonal sum. The final label of the pixel is chosen according to the maximum of the belief function.

  • 130.
    Bacauskiene, Marija
    et al.
    Department of Applied Electronics, Kaunas University of Technology, Lithuania .
    Verikas, Antanas
    Halmstad University, School of Information Science, Computer and Electrical Engineering (IDE), Halmstad Embedded and Intelligent Systems Research (EIS).
    Gelzinis, Adas
    Department of Applied Electronics, Kaunas University of Technology, Lithuania .
    Valincius, Donatas
    Department of Applied Electronics, Kaunas University of Technology, Lithuania .
    A feature selection technique for generation of classification committees and its application to categorization of laryngeal images2009In: Pattern Recognition, ISSN 0031-3203, E-ISSN 1873-5142, Vol. 42, no 5, p. 645-654Article in journal (Refereed)
    Abstract [en]

    This paper is concerned with a two phase procedure to select salient features (variables) for classification committees. Both filter and wrapper approaches to feature selection are combined in this work. In the first phase, definitely redundant features are eliminated based on the paired t-test. The test compares the saliency of the candidate and the noise features. In the second phase, the genetic search is employed. The search integrates the steps of training, aggregation of committee members, selection of hyper-parameters, and selection of salient features into the same learning process. A small number of genetic iterations needed to find a solution is the characteristic feature of the genetic search procedure developed. The experimental tests performed on five real-world problems have shown that significant improvements in Classification accuracy can be obtained in a small number of iterations if compared to the case of using all the features available.

  • 131.
    Bacauskiene, Marija
    et al.
    Department of Electrical and Control Equipment, Kaunas University of Technology, Kaunas, Lithuania.
    Verikas, Antanas
    Halmstad University, School of Information Technology, Halmstad Embedded and Intelligent Systems Research (EIS), Intelligent systems (IS-lab).
    Gelzinis, Adas
    Department of Electrical and Control Equipment, Kaunas University of Technology, Kaunas, Lithuania.
    Vegiene, Aurelija
    Department of Otolaryngology, Kaunas University of Medicine, Kaunas, Lithuania.
    Random forests based monitoring of human larynx using questionnaire data2012In: Expert systems with applications, ISSN 0957-4174, E-ISSN 1873-6793, Vol. 39, no 5, p. 5506-5512Article in journal (Refereed)
    Abstract [en]

    This paper is concerned with soft computing techniques-based noninvasive monitoring of human larynx using subject’s questionnaire data. By applying random forests (RF), questionnaire data are categorized into a healthy class and several classes of disorders including: cancerous, noncancerous, diffuse, nodular, paralysis, and an overall pathological class. The most important questionnaire statements are determined using RF variable importance evaluations. To explore data represented by variables used by RF, the t-distributed stochastic neighbor embedding (t-SNE) and the multidimensional scaling (MDS) are applied to the RF data proximity matrix. When testing the developed tools on a set of data collected from 109 subjects, the 100% classification accuracy was obtained on unseen data in binary classification into the healthy and pathological classes. The accuracy of 80.7% was achieved when classifying the data into the healthy, cancerous, noncancerous classes. The t-SNE and MDS mapping techniques applied allow obtaining two-dimensional maps of data and facilitate data exploration aimed at identifying subjects belonging to a “risk group”. It is expected that the developed tools will be of great help in preventive health care in laryngology.

  • 132.
    Baerveldt, Albert-Jan
    Halmstad University, School of Information Science, Computer and Electrical Engineering (IDE), Halmstad Embedded and Intelligent Systems Research (EIS), Intelligent systems (IS-lab).
    A vision system for object verification and localization based on local features2001In: Robotics and Autonomous Systems, ISSN 0921-8890, E-ISSN 1872-793X, Vol. 34, no 2-3, p. 83-92Article in journal (Refereed)
    Abstract [en]

    An object verification and localization system should answer the question whether an expected object is present in an image or not, i.e. verification, and if present where it is located. Such a system would be very useful for mobile robots, e.g. for landmark recognition or for the fulfilment of certain tasks. In this paper, we present an object verification and localization system specially adapted to the needs of mobile robots. The object model is based on a collection of local features derived from a small neighbourhood around automatically detected interest points. The learned representation of the object is then matched with the image under consideration. The tests, based on 81 images, showed a very satisfying tolerance to scale changes of up to 50%, to viewpoint variations of 20, to occlusion of up to 80% and to major background changes as well as to local and global illumination changes. The tests also showed that the verification capabilities are very good and that similar objects did not trigger any false verification.

  • 133.
    Baerveldt, Albert-Jan
    et al.
    Halmstad University, School of Information Science, Computer and Electrical Engineering (IDE), Halmstad Embedded and Intelligent Systems Research (EIS), Intelligent systems (IS-lab).
    Arras, Kai Oliver
    EPFL, Lausanne, Switzerland.
    Balkenius, Christian
    Lund University, Lund, Sweden.
    Editorial2003In: Robotics and Autonomous Systems, ISSN 0921-8890, E-ISSN 1872-793X, Vol. 44, no 1, p. 100p. 1-Article in journal (Other (popular science, discussion, etc.))
  • 134.
    Baerveldt, Albert-Jan
    et al.
    Halmstad University, School of Information Science, Computer and Electrical Engineering (IDE), Halmstad Embedded and Intelligent Systems Research (EIS).
    Salomonsson, Tommy
    Halmstad University, School of Information Science, Computer and Electrical Engineering (IDE), Halmstad Embedded and Intelligent Systems Research (EIS).
    Åstrand, Björn
    Halmstad University, School of Information Science, Computer and Electrical Engineering (IDE), Halmstad Embedded and Intelligent Systems Research (EIS).
    Vision-guided mobile robots for design competitions2003In: IEEE robotics & automation magazine, ISSN 1070-9932, E-ISSN 1558-223X, Vol. 10, no 2, p. 38-44Article in journal (Refereed)
    Abstract [en]

    The use of popular and effective robot-design competitions in teaching system integration in engineering curricula was discussed. Such robot competitions give students open-ended problem spaces, teaches them to work in groups and stimulates creativity. The technical and pedagogical aspects of robot competitions along with their experiences and shortcomings were also discussed.

  • 135.
    Balador, Ali
    et al.
    SICS Swedish ICT Västerås AB, Västerås, Sweden. & Polytechnic University of Valencia, Valencia, Spain.
    Böhm, Annette
    Halmstad University, School of Information Technology, Halmstad Embedded and Intelligent Systems Research (EIS).
    Calafate, Carlos T.
    Polytechnic University of Valencia, Valencia, Spain.
    Cano, Juan-Carlos
    Polytechnic University of Valencia, Valencia, Spain.
    A Reliable Token-Based MAC Protocol for V2V Communication in Urban VANET2016In: 2016 IEEE 27TH ANNUAL INTERNATIONAL SYMPOSIUM ON PERSONAL, INDOOR, AND MOBILE RADIO COMMUNICATIONS (PIMRC), Piscataway: IEEE , 2016, p. 1586-1591Conference paper (Refereed)
    Abstract [en]

    Safety applications developed for vehicular environments require every vehicle to periodically broadcast its status information (beacon) to all other vehicles, thereby avoiding the risk of car accidents in the road. Due to the high requirements on timing and reliability posed by traffic safety applications, the current IEEE 802.11p standard, which uses a random access Medium Access Control (MAC) protocol, faces difficulties to support timely and reliable data dissemination in vehicular environments where no acknowledgement or RTS/CTS (Request-to-Send/Clear-to-Send) mechanisms are adopted. In this paper, we propose the Dynamic Token-Based MAC (DTB-MAC) protocol. It implements a token passing approach on top of a random access MAC protocol to prevent channel contention as much as possible, thereby improving the reliability of safety message transmissions. Our proposed protocol selects one of the neighbouring nodes as the next transmitter; this selection accounts for the need to avoid beacon lifetime expiration. Therefore, it automatically offers retransmission opportunities to allow vehicles to successfully transmit their beacons before the next beacon is generated whenever time and bandwidth are available. Based on simulation experiments, we show that the DTB-MAC protocol can achieve better performance than IEEE 802.11p in terms of channel utilization and beacon delivery ratio for urban scenarios.

  • 136.
    Balador, Ali
    et al.
    Halmstad University, School of Information Technology. Universitat Politecnica de València, València, Spain.
    Böhm, Annette
    Halmstad University, School of Information Technology, Halmstad Embedded and Intelligent Systems Research (EIS), Centre for Research on Embedded Systems (CERES).
    Uhlemann, Elisabeth
    Halmstad University, School of Information Technology, Halmstad Embedded and Intelligent Systems Research (EIS), Centre for Research on Embedded Systems (CERES). Mälardalen University, Västerås, Sweden.
    Calafate, Carlos T.
    Universitat Politecnica de València, València, Spain.
    Cano, Juan-Carlos
    Universitat Politecnica de València, València, Spain.
    A Reliable Token-Based MAC Protocol for Delay Sensitive Platooning Applications2015In: 2015 IEEE 82nd Vehicular Technology Conference (VTC2015-Fall), [S.l.]: IEEE, 2015, article id 7390813Conference paper (Refereed)
    Abstract [en]

    Platooning is both a challenging and rewarding application. Challenging since strict timing and reliability requirements are imposed by the distributed control system required to operate the platoon. Rewarding since considerable fuel reductions are possible. As platooning takes place in a vehicular ad hoc network, the use of IEEE 802.11p is close to mandatory. However, the 802.11p medium access method suffers from packet collisions and random delays. Most ongoing research suggests using TDMA on top of 802.11p as a potential remedy. However, TDMA requires synchronization and is not very flexible if the beacon frequency needs to be updated, the number of platoon members changes, or if retransmissions for increased reliability are required. We therefore suggest a token-passing medium access method where the next token holder is selected based on beacon data age. This has the advantage of allowing beacons to be re-broadcasted in each beacon interval whenever time and bandwidth are available. We show that our token-based method is able to reduce the data age and considerably increase reliability compared to pure 802.11p. © 2015 IEEE.

  • 137.
    Balador, Ali
    et al.
    Polytechnic University of Valencia, Valencia, Spain.
    Böhm, Annette
    Halmstad University, School of Information Technology, Halmstad Embedded and Intelligent Systems Research (EIS), Centre for Research on Embedded Systems (CERES).
    Uhlemann, Elisabeth
    Mälardalen University, Västerås, Sweden.
    Calafate, Carlos T.
    Polytechnic University of Valencia, Valencia, Spain.
    Ji, Yusheng
    National Institute of Informatics, Tokyo, Japan.
    Cano, Juan-Carlos
    Polytechnic University of Valencia, Valencia, Spain.
    Manzoni, Pietro
    Polytechnic University of Valencia, Valencia, Spain.
    An Efficient MAC Protocol for vehicle platooning in automated highway systems2015Conference paper (Refereed)
    Abstract [en]

    Lately, all the top truck manufacturers are investing considerable resources in the research and development of platooning systems which would allow vehicles to save fuel and improve safety by travelling in a close-following manner. The platooning system requires frequent and reliable vehicle-to-vehicle communications. As platooning takes place in a vehicular ad hoc network, the use of IEEE 802.11p is close to mandatory. However, the 802.11p medium access method suffers from packet collisions and random delays. Most ongoing research suggests using TDMA on top of 802.11p as a potential remedy. However, TDMA requires synchronization and is not very flexible if the beacon frequency needs to be updated, the number of platoon members changes, or if re-transmissions for increased reliability are required. We therefore suggest a token-passing medium access method where the next token holder is selected based on beacon data age. This has the advantage of allowing beacons to be re-broadcasted in each beacon interval whenever time and bandwidth are available. We show that our token-based method is able to reduce the data age and considerably increase reliability considerably compared to pure 802.11p.

  • 138.
    Balaji Kamalakkannan, Balaji
    Halmstad University, School of Information Technology, Halmstad Embedded and Intelligent Systems Research (EIS).
    Modelling and Simulation of Vehicle Kinematics and Dynamics2017Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    With the rapid growth in the automotive industry, vehicles have become more complex and sophisticated. Vehicle development today, involves integration of both electrical and mechanical systems. Their design and production are typically time and cost critical. To complement and support the process of vehicle development and design, majority of the automotive industry use modelling and simulationfor testing automotive applications, vehicle subsystems or the vehicle behaviour in its entirety.

    For the purpose of traffic simulations, where a large number of vehicles and other elements of the road network are simulated, implementing a highly complex vehicle model would greatly affect the performance of the simulation. The complexity of the vehicle model would entail a higher computation time of the system, making it unsuitable for any real time application. There in lies the trade-off indesigning a model that is both fast and accurate. The majority of the vehicle models that have been designed are either domain specific, highly complex or generalized. Thus, in this thesis, two class specific vehicles’ kinematic models with good accuracy and low computation time are presented.

    Two different modelling paradigms have been adopted to design and test these models. The results, challenges and limitations that pertain to these paradigms are also presented and discussed. The results show the feasibility of the proposed kinematic models.

  • 139.
    Balasubramaniam, Sasitharan
    et al.
    Tampere University of Technology, Tampere, Finland .
    Lyamin, Nikita
    Halmstad University, School of Information Technology, Halmstad Embedded and Intelligent Systems Research (EIS), Centre for Research on Embedded Systems (CERES).
    Kleyko, Denis
    Luleå University of Technology, Luleå, Sweden.
    Skurnik, Mikael
    University of Helsinki, Helsinki, Finland .
    Vinel, Alexey
    Halmstad University, School of Information Technology, Halmstad Embedded and Intelligent Systems Research (EIS), Centre for Research on Embedded Systems (CERES).
    Koucheryavy, Yevgeni
    Tampere University of Technology, Tampere, Finland .
    Exploiting bacterial properties for multi-hop nanonetworks2014In: IEEE Communications Magazine, ISSN 0163-6804, E-ISSN 1558-1896, Vol. 52, no 7, p. 184-191Article 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 the ability to swim and migrate between locations, carry DNA contents (i.e. plasmids) that could be utilized for information storage, and interact and transfer plasmids to other bacteria (one of these processes 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 multihop communication between nanomachines. Simulations of the communication process have also been evaluated, to analyze the quantity of bits 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. © 2014 IEEE.

  • 140.
    Bangalore Girijeswara, Karthik
    Halmstad University, School of Information Technology, Halmstad Embedded and Intelligent Systems Research (EIS), CAISR - Center for Applied Intelligent Systems Research. Mr..
    Peer group recognition based on Vehicle operation and behavior: Supervised and unsupervised approach towards peer group recognition and feature space exploration2017Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Behavior recognition provides an interesting perspective for understandingthe different modes of a system and the influence of eachmode under varying conditions. In most of the systems, prior knowledgeof different expected behavior is available. Whereas, in an automotivedomain, a fleet of vehicle with many external factors influencingeach vehicle and an asynchronous performance of each vehicleon road, creates the complexity on analyzing and predicting the exacttime segments of vehicles in a fleet exhibiting similar behavior. Thisthesis focuses on recognizing time segments of vehicles that exhibitsimilar behavior based on supervised and unsupervised approaches.In supervised approach, classifiers are trained to predict two distinctiveoperations(highway and in-city). In unsupervised approach, featurespace is explored for identification of consistent features and existenceof other operations. An unsupervised approach to recognizepeer cluster groups is combined with supervised classification resultsto achieve lower computational complexity.

  • 141.
    Barisas, Dominykas
    et al.
    Kaunas University of Technology, Kaunas, Lithuania.
    Duracz, Adam
    Halmstad University, School of Information Technology, Halmstad Embedded and Intelligent Systems Research (EIS), Centre for Research on Embedded Systems (CERES).
    Taha, Walid
    Halmstad University, School of Information Technology, Halmstad Embedded and Intelligent Systems Research (EIS), Centre for Research on Embedded Systems (CERES). Rice University, Houston, TX, USA.
    DSLs Should be Online Applications2014In: Joint International Conference on Engineering Education & International Conference on Information Technology: ICEE/ICIT-2014: June 2 - 6, 2014: Riga, Latvia: Conference proceedings, 2014, p. 314-319Conference paper (Refereed)
    Abstract [en]

    Domain-Specific Languages (DSLs) play an important role in both practice and education. But developing them is challenging, because a DSL must ultimately satisfy a large and complex set of user/customer requirements to fulfil its intended role, and neither requirements nor users are fully available at all times during the development process. Requirements can be elicited using agile methods but such methods assume the availability of the users. The situation is further complicated when the user base is primarily students and when enhanced learning is a key requirement. In this paper we propose developing DSLs, especially educational ones, as online applications. We analyze how this can help requirement elicitation and learning. Being online brings language development closer to the user, yielding new opportunities to improve and accelerate the language design process. It is also well-matched to agile methods, since web- based analytics provide an abundant source of data that integrates naturally into the development process. As an example, we consider applying the method to Acumen, a DSL designed to support teaching Cyber-Physical Systems.

  • 142.
    Bellalta, Boris
    et al.
    Universitat Pompeu Fabra, Barcelona, Spain.
    Belyaev, Evgeny
    Tampere University of Technology, Finland.
    Jonsson, Magnus
    Halmstad University, School of Information Technology, Halmstad Embedded and Intelligent Systems Research (EIS), Centre for Research on Embedded Systems (CERES).
    Vinel, Alexey
    Halmstad University, School of Information Technology, Halmstad Embedded and Intelligent Systems Research (EIS), Centre for Research on Embedded Systems (CERES).
    Performance evaluation of IEEE 802.11p-enabled vehicular video surveillance system2014In: IEEE Communications Letters, ISSN 1089-7798, E-ISSN 1558-2558, Vol. 18, no 4, p. 708-711Article in journal (Refereed)
    Abstract [en]

    Prospective IEEE 802.11p-based vehicular surveillance system, where video from the vehicle on-board camera is transmitted to the management center, is considered. Multi-hop transmission from the vehicle to the nearest roadside unit and then-via other roadside units-to the gateway is addressed. In this letter we assess the feasibility of such system by analyzing the video end-to-end distortion for a target vehicle, located several hops away from the gateway, when it is alone or there are also other vehicles transmitting video. We demonstrate the importance of dynamic adaptation of the video bit rate of each vehicle depending on the number and positions of the participating vehicles. © 2014 IEEE.

  • 143.
    Bellalta, Boris
    et al.
    Universitat Pompeu Fabra, Barcelona, Spain.
    Vinel, AlexeyDepartment of Communications Engineering, Tampere University of Technology, Finland.Jonsson, MagnusHalmstad University, School of Information Science, Computer and Electrical Engineering (IDE), Halmstad Embedded and Intelligent Systems Research (EIS), Centre for Research on Embedded Systems (CERES).Barcelo, JaumeUniversitat Pompeu Fabra, Barcelona, Spain.Maslennikov, RomanUniversity of Nizhny Novgorod, Russia.Chatzimisios, PeriklisAlexander Technological Educational Institute of Thessaloniki Sindos, Greece.Malone, DavidNational University of Ireland, Maynooth, Ireland.
    Multiple Access Communications: 5th International Workshop, MACOM 2012, Maynooth, Ireland, November 19-20, 2012. Proceedings2012Conference proceedings (editor) (Refereed)
    Abstract [en]

    The proceedings contain 18 papers. The topics discussed include: network coding as a WiMAX link reliability mechanism; initialization procedure of wireless network coding with hierarchical decode and forward strategy in random connectivity networks; a coded DHA FH OFDMA system with a noncoherent ML detector under multitone jamming; analysis of inter-RSU beaconing interference in VANETs; survey of energy efficient tracking and localization techniques in buildings using optical and wireless communication media; network coding as a WiMAX link reliability mechanism: an experimental demonstration; spectrum sensing with USRP-E110; power control for wireless networks with a limited number of channels; a measurement study for predicting throughput from LQI and RSSI; reality considerations when designing a TDMA-FDMA based link-layer for real-time WSN; and wireless groupcast routing with palette of transmission methods.

  • 144.
    Bellalta, Boris
    et al.
    Universitat Pompeu Fabra, Barcelona, Spain.
    Zocca, Alessandro
    Eindhoven University of Technology, Eindhoven, The Netherlands.
    Cano, Cristina
    Hamilton Institute, Maynooth, Ireland.
    Checco, Alessandro
    Hamilton Institute, Maynooth, Ireland.
    Barcelo, Jaume
    Universitat Pompeu Fabra, Barcelona, Spain.
    Vinel, Alexey
    Halmstad University, School of Information Technology, Halmstad Embedded and Intelligent Systems Research (EIS), Centre for Research on Embedded Systems (CERES).
    Throughput Analysis in CSMA/CA Networks Using Continuous Time Markov Networks: A Tutorial2014In: Wireless Networking for Moving Objects / [ed] Ivan Ganchev, Marília Curado, Andreas Kassler, Cham: Springer, 2014, p. 115-133Chapter in book (Refereed)
    Abstract [en]

    This book chapter introduces the use of Continuous Time Markov Networks (CTMN) to analytically capture the operation of Carrier Sense Multiple Access with Collision Avoidance (CSMA/CA) networks. It is of tutorial nature, and it aims to be an introduction on this topic, providing a clear and easy-to-follow description. To illustrate how CTMN can be used, we introduce a set of representative and cutting-edge scenarios, such as Vehicular Ad-hoc Networks (VANETs), Power Line Communication networks and multiple overlapping Wireless Local Area Networks (WLANs). For each scenario, we describe the specific CTMN, obtain its stationary distribution and compute the throughput achieved by each node in the network. Taking the per-node throughput as reference, we discuss how the complex interactions between nodes using CSMA/CA have an impact on system performance.

  • 145.
    Belova, Anna
    et al.
    Halmstad University, School of Information Science, Computer and Electrical Engineering (IDE).
    Shmidt, Tamara
    Halmstad University, School of Information Science, Computer and Electrical Engineering (IDE), Halmstad Embedded and Intelligent Systems Research (EIS), MPE-lab.
    Meshfree methods in option pricing2011Independent thesis Advanced level (degree of Master (One Year)), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    A meshfree approximation scheme based on the radial basis function methods is presented for the numerical solution of the options pricing model. This thesis deals with the valuation of the European, Barrier, Asian, American options of a single asset and American options of multi assets. The option prices are modeled by the Black-Scholes equation. The θ-method is used to discretize the equation with respect to time. By the next step, the option price is approximated in space with radial basis functions (RBF) with unknown parameters, in particular, we con- sider multiquadric radial basis functions (MQ-RBF). In case of Ameri- can options a penalty method is used, i.e. removing the free boundary is achieved by adding a small and continuous penalty term to the Black- Scholes equation. Finally, a comparison of analytical and finite difference solutions and numerical results from the literature is included.

  • 146.
    Belova, Anna
    et al.
    Halmstad University, School of Information Technology.
    Shmidt, Tamara
    Halmstad University, School of Information Technology, Halmstad Embedded and Intelligent Systems Research (EIS).
    Ehrhardt, Matthias
    AMNA, Bergische Universität Wuppertal, Wuppertal, Germany.
    Meshfree methods in option pricing2012Conference paper (Refereed)
    Abstract [en]

    A meshfree approximation scheme based on the radial basis function (RBF) methods is presented for the numerical solution of the options pricing model. This work deals with the valuation of the European, Asian and American options. The option prices are modeled by the Black-Scholes equation. The θ-method is used to discretize the equation with respect to time. Next, the option price is approximated in space with RBF. In case of American options a penalty method is used, i.e. the free boundary is removed by adding a small and continuous penalty term to the Black-Scholes equation. Finally, we present a comparison of analytical and finite difference solutions and numerical results. © 2012 MANT.

  • 147.
    Belwal, Chaitanya
    et al.
    Dept. of Computer Science, University of Houston, Houston, USA.
    Cheng, Albert M.K.
    Dept. of Computer Science, University of Houston, Houston, USA.
    Taha, Walid
    Halmstad University, School of Information Technology, Halmstad Embedded and Intelligent Systems Research (EIS), Centre for Research on Embedded Systems (CERES).
    Release Offset Bounds for Response Time Analysis of P-FRP using Exhaustive Enumeration2011In: 2011 IEEE 10th International Conference on Trust, Security and Privacy in Computing and Communications (TrustCom), Piscataway, N.J.: IEEE Press, 2011, p. 950-957Conference paper (Refereed)
    Abstract [en]

    Functional*Reactive Programming (FRP) is a declarative approach to modeling and building reactive systems. Priority-based FRP (P-FRP) is a formalism of FRP that guarantees real-time response. Unlike the classical preemptive model1 of real-time systems, preempted tasks in PFRP are aborted and have to restart when higher priority tasks have completed. Due to this abort-restart of nature of preemption, there is no single critical instant of release that leads to Worst-Case Response Time (WCRT) of lower priority P-FRP tasks. At this time, the only method for determining the WCRT is through an exhaustive enumeration of all release offsets of higher priority tasks between the release and deadline of the lower priority task. This makes the computational cost of WCRT dependent on the deadline of a task, and when such deadlines are large the computational costs of this technique make it infeasible even for small task sets. In this paper, we show that the release offsets of higher priority tasks have a lower and upper bound and present techniques to derive these bounds. By enumerating only those release offsets while lie within our derived bounds the number of release scenarios that have to be enumerated is significantly reduced. This leads to lower computational costs and makes determination of the WCRT in P-FRP a practically feasible proposition. © 2011 IEEE.

  • 148.
    Belyaev, Evgeny
    et al.
    Department of Signal Processing, Tampere University of Technology, Tampere, Finland.
    Molchanov, Pavlo
    Department of Signal Processing, Tampere University of Technology, Tampere, Finland.
    Vinel, Alexey
    Halmstad University, School of Information Technology, Halmstad Embedded and Intelligent Systems Research (EIS), Centre for Research on Embedded Systems (CERES). Department of Electronics and Communication Engineering, Tampere University of Technology, Tampere, Finland.
    Koucheryavy, Yevgeni
    Department of Electronics and Communication Engineering, Tampere University of Technology, Tampere, Finland.
    The Use of Automotive Radars in Video-Based Overtaking Assistance Applications2013In: IEEE transactions on intelligent transportation systems (Print), ISSN 1524-9050, E-ISSN 1558-0016, Vol. 14, no 3, p. 1035-1042, article id 649464Article in journal (Refereed)
    Abstract [en]

    Overtaking on rural roads may cause severe accidents when oncoming traffic is detected by a driver too late, or its speed is underestimated. Recently proposed cooperative overtaking assistance systems are based on real-time video transmission, where a video stream captured with a camera installed at the windshield of a vehicle is compressed, broadcast through the wireless channel, and displayed to the drivers of vehicles driving behind. In such a system, it is of ultimate importance to deliver video information about the opposite lane with low end-to-end latency and good visual quality. In this paper, we propose reallocating the wireless channel resources in favor of the part of the captured video frame containing the image of the oncoming vehicle. To achieve this goal, we apply automotive radar for oncoming vehicle detection, and we use the image of this vehicle as a region-of-interest (ROI) for the video rate control. We present the theoretical framework, which describes the basics of such an approach and can serve as a useful guideline for the future practical implementation of the overtaking assistance systems. The benefits of our proposal are demonstrated in relation to the practical scenario of H.264/Advance Video Coding (AVC), IEEE 802.11p/Wireless Access for Vehicular Environments (WAVE) intervehicle communication standards, and currently used automotive radars.

  • 149.
    Belyaev, Evgeny
    et al.
    Technical University of Denmark, Lyngby, Denmark.
    Moreschini, Sergio
    Tampere University of Technology, Tampere, Finland.
    Vinel, Alexey
    Halmstad University, School of Information Technology, Halmstad Embedded and Intelligent Systems Research (EIS), Centre for Research on Embedded Systems (CERES).
    Uncoordinated multi-user video streaming in VANETs using Skype2017In: 2017 IEEE 22nd International Workshop on Computer Aided Modeling and Design of Communication Links and Networks (CAMAD), 2017Conference paper (Refereed)
    Abstract [en]

    Real-time video delivery in Vehicle-to-Infrastructure (V2I) scenario enables a variety of multimedia vehicular services. We conduct experiments with Dedicated Short Range Communications (DSRC) transceivers located in the mutual proximity and exchanging Skype video calls traffic. We demonstrate that the lack of coordination between the users both at the application as well as Medium Access Control (MAC) layers results in problems with quality of service provisioning even for the setup without vehicular mobility. © Copyright 2017 IEEE

  • 150.
    Belyaev, Evgeny
    et al.
    Tampere University of Technology, Tampere, Finland.
    Vinel, Alexey
    Halmstad University, School of Information Technology, Halmstad Embedded and Intelligent Systems Research (EIS), Centre for Research on Embedded Systems (CERES).
    Poster: Target Packet Loss Selection for Inter-Packet Loss Protection for Video Streaming Over VANETs2014In: 2014 IEEE Vehicular Networking Conference (VNC) / [ed] Falko Dressler, Onur Altintas, Suman Banerjee, Björn Scheuermann & David Eckhoff, Piscataway, N.J.: IEEE Press, 2014, p. 197-198Conference paper (Refereed)
    Abstract [en]

    This work is dedicated to a live video streaming in vehicular networks where the application-based inter-packet forward error correction is used for the packet loss protection. A practical way to apply such a protection at the video encoder side for the unknown channel loss rate is proposed. Experimental results which demonstrate the performance for the proposed approach for a scalable extension of the H.264/AVC standard (H.264/SVC) and for the non-standardized video codec based on three-dimensional discrete wavelet transform (3-D DWT) are provided.

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