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  • 2901.
    Yu, Kan
    et al.
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Åkerberg, Johan
    ABB AB Corporate Research, Sweden.
    Gidlund, Mikael
    ABB AB Corporate Research, Sweden.
    Björkman, Mats
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Realization and Measurements of Industrial Wireless Sensor and Actuator Networks2015Conference paper (Refereed)
    Abstract [en]

    Industrial automation can benefit from applying wireless sensor and actuator networks (WSAN) on cost reduction, mobility and flexibility. However, wireless solutions are more prone to interferences compared to wired ones. In order to avoid production losses and to keep the revenues at an anticipated level, it is of utmost importance for WSANs to meet the stringent requirements from industrial automation, such as high reliability and real-time performance. A great number of research efforts were taken in this field based on simulations, but simulation results may not show sufficient confidence. Existing implementations and products compatible with the standards may still fail to provide reliable and real-time communication. Therefore, in this paper we built a prototype of industrial wireless sensor and actuator networks (IWSAN) and implemented a protocol stack, aiming for providing reliable and real-time communication for mission-critical industrial applications. Afterwards, we deployed our prototype and conducted measurements in real industrial environments. Our measurement results exhibited possibility of applying IWSANs for industrial applications and brought more evidence to our industry.

  • 2902. Yuen, Chau
    et al.
    Elkashlan, Maged
    Qian, Yi
    Duong, Trung Q.
    Blekinge Institute of Technology, Faculty of Computing, Department of Communication Systems.
    Shu, Lei
    Schmidt, Frank
    ENERGY HARVESTING COMMUNICATIONS: PART III2015In: IEEE Communications Magazine, ISSN 0163-6804, E-ISSN 1558-1896, Vol. 53, no 8, p. 90-91Article in journal (Other academic)
  • 2903.
    Yüksel, Hüsamettin
    Linnaeus University, Faculty of Technology, Department of Computer Science.
    GaniFA NG: The Next Generationof Algorithm Visualizations of FiniteAutomata2014Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Software visualization is a promising field in computer science. Visualizationof software-related data deals with aspects that are connected with the visualrepresentation of computational data sets or simulations in order to achievea deeper understanding or a simpler representation of a more complex phenomenon.Interactive software visualizations are also valuable active learningtechniques that can improve explorative learning in computer science. Sincedynamic processes such as the working of an algorithm or the flow of informationbetween computing entities are not well explained by static media styleslike text or images visualization has a substantial role in effective learning.In this thesis, we will study on modernization of an educational softwarecalled GaniFA which was developed for the visualization of finite automata atthe end of 1990s. The modernized software is called GaniFA NG (Next Generation)and enables designing finite automata and simulating all the functioningprocesses.We will discuss benefits of visualization in automata theory learning andthe software development life cycle of our proposed visualization tool in thisreport, and the experience derived from the implementation process will alsobe documented.

  • 2904.
    Zafari, Afshin
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Division of Scientific Computing. Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computational Science.
    Advances in Task-Based Parallel Programming for Distributed Memory Architectures2018Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    It has become common knowledge that parallel programming is needed for scientific applications, particularly for running large scale simulations. Different programming models are introduced for simplifying parallel programming, while enabling an application to use the full computational capacity of the hardware. In task-based programming, all the variables in the program are abstractly viewed as data. Parallelism is provided by partitioning the data. A task is a collection of operations performed on input data to generate output data. In distributed memory environments, the data is distributed over the computational nodes (or processes), and is communicated when a task needs remote data.

    This thesis discusses advanced techniques in distributed task-based parallel programming, implemented in the DuctTeip software library. DuctTeip uses MPI (Message Passing Interface) for asynchronous inter-process communication and Pthreads for shared memory parallelization within the processes. The data dependencies that determine which subsets of tasks can be executed in parallel are extracted from information about the data accesses (input or output) of the tasks. A versioning system is used internally to represent the task-data dependencies efficiently. A hierarchical partitioning of tasks and data allows for independent optimization of the size of computational tasks and the size of communicated data. A data listener technique is used to manage communication efficiently.

    DuctTeip provides an algorithm independent dynamic load balancing functionality. Redistributing tasks from busy processes to idle processes dynamically can provide an overall shorter execution time. A random search method with high probability of success is employed for locating idle/busy nodes.

    The advantage of the abstract view of tasks and data is exploited in a unified programming interface, which provides a standard for task-based frameworks to decouple framework development from application development. The interface can be used for collaboration between different frameworks in running an application program efficiently on different hardware.

    To evaluate the DuctTeip programming model, applications such as Cholesky factorization, a time-dependent PDE solver for the shallow water equations, and the fast multipole method have been implemented using DuctTeip. Experiments show that DuctTeip provides both scalability and performance. Comparisons with similar frameworks such as StarPU, OmpSs, and PaRSEC show competitive results.

  • 2905.
    Zafarzadeh, Masoud
    et al.
    Mälardalen University, School of Innovation, Design and Engineering.
    Vedapatti Ranganathan, Hariram
    Mälardalen University, School of Innovation, Design and Engineering.
    Kurdve, Martin
    Mälardalen University, School of Innovation, Design and Engineering.
    Sustainable supply chain management in automotive industry- Supplier company relationship and Integration management challenge2012In: International Journal of Academic Conference Proceedings, v. 1, n. 2, 2012, Institute of Management Technology, 2012Conference paper (Refereed)
    Abstract [en]

    Growing competition in automotive industry has forced companies to have serious attention towards the sustainability concept. Obviously environmental, social and economic challenges do not only happen inside companies, but rather involves the whole supply chain process. Most of the practical efforts are focusing on manufacturing phase and less attention has been paid to supply and distribution areas. However, it is not possible to achieve a sustainable supply chain unless the current situation is accurately mapped and long term policies toward a sustainable future state are defined. In this respect, the authors consider two major challenges, first supplier coordination with sustainability requirements and second investigating the alliance of current managerial policies. In theory, the paper aim is to represent sustainable supply chain management by focusing on supplier company relations. Integration as a vital element to meet sustainable supply chain is discussed by exploring the coherence of lean and green with sustainability. In practice, three leading automotive companies’ Sustainable Supply Chain Management (SSCM) systems (TOYOTA, VOLVO and Volkswagen) are investigated in order to figure out their perspective toward SSCM.

  • 2906.
    Zagar, Alexander
    et al.
    Jönköping University, School of Engineering, JTH, Computer Science and Informatics.
    Ekelund, Jonathan
    Jönköping University, School of Engineering, JTH, Computer Science and Informatics.
    Skapandet av ett webbaserat ärendehanteringssystem för affärssystemet Pyramid med Scrum: Creation of a web based case management system for the business system Pyramid with Scrum2014Independent thesis Basic level (university diploma), 10 credits / 15 HE creditsStudent thesis
    Abstract [sv]

    The business system known as Pyramid does today not provide its user with a reasonable system regarding case management for support issues. The current system in place requires the customer to contact its provider via telephone to register new cases. In addition to this, current system doesn’t include any way for the user to view any of their current cases without contacting the provider.A solution to this issue is to migrate the current case management system from a telephone contact to a web based platform, where customers could easier access their current cases, but also directly through the website create new cases. This new system would reduce the time required to manually manage each individual case, for both customer and provider, resulting in an overall reduction in cost for both parties.The result is a system divided into two different sections, the first one is an API created in Pyramid that acts as a web service, and the second one a website which customers can connect to. The website will allow users to overview their current cases, but also the option to create new cases directly through the site. All the information used to the website is obtained through the web service inside Pyramid. Analyzing the final design of the system, the developers where able to conclude both positive and negative aspects of the systems’ final design. If the platform chosen was the optimal choice or not, and also what can be include if the system is further developed, will be discussed.The development process and the method used during development will also be analyzed and discussed, what positive and negative aspects that where encountered. In addition to this the cause and effect of a development team smaller than the suggested size will also be analyzed. Lastly an analysis of actions that could’ve been made in order to prevent certain issues from occurring will.

  • 2907.
    Zaharans, Eriks
    Linköping University, Department of Computer and Information Science. Linköping University, The Institute of Technology.
    Indoor robot localization and collaboration2013Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The purpose of this thesis is to create an indoor rescue scenario with multiple self-localizing robots that are able to collaborate for a victim search. Victims are represented by RFID tags and detecting them combined with an accurate enough location data is considered as a successful finding. This setup is created for use in a laboratory assignment at Linköping University.

    We consider the indoor localization problem by trying to use as few sensors as possible and implement three indoor localization methods - odometry based, passive RFID based, and our approach by fusing both sensor data with particle filter.The Results show that particle filter based localization performs the best in comparison to the two other implemented methods and satisfies the accuracy requirements stated for the scenario.

    The victim search problem is solved by an ant mobility (pheromone-based) approach which integrates our localization method and provides a collaborative navigation through the rescue area. The purpose of the pheromone mobility approach is to achieve a high coverage with an acceptable resource consumption.Experiments show that area is covered with approximately 30-40% overhead in traveled distance comparing to an optimal path.

  • 2908.
    Zaidi, Ali A.
    et al.
    KTH, School of Electrical Engineering (EES), Communication Theory. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Khormuji, Majid Nasiri
    KTH, School of Electrical Engineering (EES), Communication Theory. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Skoglund, Mikael
    KTH, School of Electrical Engineering (EES), Communication Theory. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Nonlinear transmission strategies for a general half-duplex AWGN relay channel2011In: 2011 IEEE Swedish Communication Technologies Workshop, Swe-CTW 2011, 2011, p. 58-61Conference paper (Refereed)
    Abstract [en]

    We consider the general AWGN relay channel consisting of a source node, a half-duplex relay node and a destination node. We propose a low-complex and memoryless nonlinear transmission scheme for delay sensitive applications. The proposed nonlinear strategy provides higher achievable transmission rates than those achieved by the existing linear strategy.

  • 2909.
    Zain-ul-Abdin,
    et al.
    Halmstad University, School of Information Science, Computer and Electrical Engineering (IDE), Halmstad Embedded and Intelligent Systems Research (EIS), Embedded Systems (CERES).
    Svensson, Bertil
    Halmstad University, School of Information Science, Computer and Electrical Engineering (IDE), Halmstad Embedded and Intelligent Systems Research (EIS), Embedded Systems (CERES).
    Compiling Stream-Language Applications to a Reconfigurable Array Processor2005In: ERSA'05: proceedings of the 2005 International Conference on Engineering of Reconfigurable Systems and Algorithms, Las Vegas, Nevada, USA, June 27-30, 2005 / [ed] Toomas P. Plaks and R. DeMara, Las Vegas: CSREA Press, 2005, p. 274-275Conference paper (Refereed)
  • 2910.
    Zak, Edvard
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Division of Visual Information and Interaction.
    Including Smartphone End User Apps in the Context of the Company Contact Center2014Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Smartphones are becoming increasingly popular, with the result that customers prefer to carry out at least some customer services using an app on a mobile device. Among app users, smooth transfer to a live agent is seen as an important feature and this means that the company contact center need a solution to handle this as well as increasing numbers of interactions. The question this thesis tries to answer is "how can smartphone end user apps be included in the context of the company contact center"? To answer this question research was conducted regarding the possibilities of an Android smartphone, with the results of this research being used to define a use case, a state flow diagram and create a demonstration app. The thesis showed that it is possible to have an app as an online channel for customer service interactions. New possibilities in comparison to traditional telephony include that customer data such as topic, authentication, location and multimedia can be sent to the contact center before an actual interaction is started.

  • 2911.
    Zakupszki, Andras
    et al.
    Mälardalen University, School of Innovation, Design and Engineering.
    Pichetpongsa, Nuttapon
    Mälardalen University, School of Innovation, Design and Engineering.
    Extending ABB’s WirelessHART Tool2013Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Within this decade, wireless technology has been used in process control in various industries. WirelessHART is one of the standards, used for creating communication networks for such purpose. Since the technology is relatively new, there are many known and unknown risks in deploying it in real life applications.ABB’s WirelessHART Tool is used for generating simulation scenarios that can be used for evaluating the performance of WirelessHART networks under different conditions.This paper describes in detail, how ABB’s WirelessHART Tool was extended by adding various new functionalities. The topics cover what obstacles we have faced, which solutions were used and why, how our solutions were evaluated and the outcomes. Furthermore, the paper documents the application structure of WirelessHART Tool.

  • 2912.
    Zamansky, A.
    et al.
    University of Haifa, Carmel Mountain, Haifa, Israel .
    Rodriguez-Navas, Guillermo
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Adams, M.
    Proof Technologies Ltd., Worcester, United Kingdom.
    Spichkova, M.
    RMIT University, Melbourne, Australia .
    Formal methods in collaborative projects2016In: ENASE 2016 - Proceedings of the 11th International Conference on Evaluation of Novel Software Approaches to Software Engineering, 2016, p. 396-402Conference paper (Refereed)
    Abstract [en]

    In this paper we address particular aspects of integration of formal methods in large-scale industrial projects, namely collaborative aspects. We review recent works addressing such aspects, identify some current trends and discuss directions for further research. 

  • 2913.
    Zamanzad Ghavidel, Alireza
    Linnaeus University, Faculty of Technology, Department of Informatics.
    Technology Enhanced Learning (TEL) Development and Research: An infrastructural study2014Independent thesis Advanced level (degree of Master (One Year)), 10 credits / 15 HE creditsStudent thesis
  • 2914. Zargar, S. T.
    et al.
    Moulavi, M. Amir
    KTH, School of Information and Communication Technology (ICT), Communication: Services and Infrastucture (Closed 20120101), Software and Computer Systems, SCS (Closed 20120101).
    Buyya, R.
    Naghibzadeh, M.
    Joshi, J. B. D.
    RRNA: Reliable soft real-time network aware grid scheduling algorithm using round trip time2009In: Spring Simulation Multiconference 2009 - Co-located with the 2009 SISO Spring Simulation Interoperability Workshop, Association for Computing Machinery (ACM), 2009, article id 78Conference paper (Refereed)
    Abstract [en]

    Assigning jobs to optimum resources in a grid environment is the main aim of a grid scheduler. Communication cost has always been an important issue in grid environments. Proposing new scheduling algorithms to consider this cost accurately and allocate jobs to an optimum resource efficiently has always been of great importance. In this paper we have proposed a grid scheduling algorithm that is aware of the costs for different network paths.We have also considered soft realtime characteristics of jobs in our proposed algorithm. We have simulated and compared our algorithm with some key scheduling algorithms such as Least Load First (LLF), Random, and First Come First Served (FCFS) in Gridsim by considering soft real-time jobs. Results show the superiority of our scheduling algorithm due to its ability to predict network cost and to satisfy the demands of soft real-time tasks.

  • 2915.
    zeng, yingfu
    Halmstad University, School of Information Science, Computer and Electrical Engineering (IDE), Halmstad Embedded and Intelligent Systems Research (EIS).
    Lightweight Three-Dimensional Visualization For Hybrid Systems Simulation2012Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Simulation plays a key role in the computer-aided design of systems, primarily because it helps in catching design bugs at an early stage and in quickly ruling out many unreasonable options in the design space. There is a wealth of tools and languages that have been proposed over the years for the design and verification of hybrid systems and most of them provide 3D visualization utility for facilitating design process. However, their visualization systems often rely on some external configuration files written in naive 3D APIs like VRML or Java3D and complicated connections have to be established between the simulation data and the visualization. Numerous efforts have to be invested in visualization related modeling and certain level of understanding of the low level 3D libraries are needed. Thus it is not an easy job for non-professions to build a 3D visualization. In this thesis we explore the idea that in a hybrid system model, almost all the information need for visualization is already in place. This means that very few annotation should be enough to fully specify a useful 3D visualization. Based on this idea, we propose a lightweight 3D visualization framework which allows the user to expresses the three-dimensional object in a high level and abstract way and to take advantage of the data already in the simulation. We evaluate our approaching by building a prototype extension of modeling language called Acumen. The result of this thesis work is included in Acumen's official release version that can be download at www.acumen-language.org. To build a 3D visualization in Acumen, only very few annotations need to be added to the simulation model and are included inside one reserved variable. Non-professions like students who are studying Cyber-physical systems can easily use this tool to visualize their models in Acumen without any prerequisite knowledge regarding 3D visualization technology. We also developed a number of benchmarks to test the correctness and functionality of Acumen3D. Besides, as a lager case study into the expressivity of Acumen and its visualizaiton efficiency, we developed a simplified model of a Ping Pong game. We gained experience about how to model complex hybrid system in Acumen. Moreover by comparing modeling such a hybrid system in Java3D and in Acumen3D, we find concrete evidence that modelling it in Acumen3D is easier in that of less code and less prerequisite knowledge and more supporting built in functions. 

  • 2916.
    Zhalgasbekova, Aigerim
    Luleå University of Technology.
    CollMule: An Opportunistic Data Collection System for IoT-based Indoor Air Quality Monitoring2017Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
  • 2917.
    Zhang, Ge
    Karlstad University, Faculty of Economic Sciences, Communication and IT, Department of Computer Science.
    Analyzing Key-Click Patterns of PIN Input for Recognizing VoIP Users2011In: Future Challenges in Security and Privacy for Academia and Industry / [ed] Camenisch, J.; Fischer-Hübner, S.; Murayama, Y.; Portmann, A.; Rieder, C., Springer-Verlag New York, 2011, p. 247-258Conference paper (Refereed)
    Abstract [en]

    Malicious intermediaries are able to detect the availability of VoIP conversation flows in a network and observe the IP addresses used by the conversation partners. However, it is insufficient to infer the calling records of a particular user in this way since the linkability between a user and a IP address is uncertain: users may regularly change or share IP addresses. Unfortunately, VoIP flows may contain human-specific features. For example, users sometimes are required to provide Personal identification numbers (PINs) to a voice server for authentication and thus the key-click patterns of entering a PIN can be extracted from VoIP flows for user recognition. We invited 31 subjects to enter 4-digital PINs on a virtual keypad of a popular VoIP user-agent with mouse clicking. Employing machine learning algorithms, we achieved average equal error rates of 10-29% for user verification and a hitting rate up to 65% with a false positive rate around 1% for user classification.

  • 2918.
    Zhang, Ge
    Karlstad University, Faculty of Economic Sciences, Communication and IT, Department of Computer Science.
    Timing Attacks on a Centralized Presence Model2011In: IEEE International Conference on Communications 2011, IEEE Press, 2011, p. 1-5Conference paper (Refereed)
    Abstract [en]

    Presence information (PI) represents the updated status, context and willingness of communication partners in Voice over IP systems. For instance, the action that Alice switches her status (e.g., from "idle" to "busy") will trigger PI messages to notify her buddies this change. In a centralized presence service system, presence communications are managed by a presence server based on users' buddylists. The privacy concern in this paper is that networking intermediaries, as adversaries, might be able to profile the buddy-relationship among the users by utilizing message arrival time. We found that the threat cannot be totally eliminated even if the server processes messages in batches. Attackers might observe the traffic in several rounds and thus profile the results. In this paper, we introduce the attacks and discuss potential countermeasures.

  • 2919.
    Zhang, Ge
    Karlstad University, Faculty of Economic Sciences, Communication and IT, Department of Computer Science.
    Unwanted Traffic and Information Disclosure in VoIP Networks: Threats and Countermeasures2012Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The success of the Internet has brought significant changes to the telecommunication industry. One of the remarkable outcomes of this evolution is Voice over IP (VoIP), which enables realtime voice communications over packet switched networks for a lower cost than traditional public switched telephone networks (PSTN). Nevertheless, security and privacy vulnerabilities pose a significant challenge to hindering VoIP from being widely deployed. The main object of this thesis is to define and elaborate unexplored security and privacy risks on standardized VoIP protocols and their implementations as well as to develop suitable countermeasures. Three research questions are addressed to achieve this objective:

    Question 1:  What are potential unexplored threats in a SIP VoIP network with regard to availability, confidentiality and privacy by means of unwanted traffic and information disclosure?

    Question 2:  How far are existing security and privacy mechanisms sufficient to counteract these threats and what are their shortcomings?

    Question 3:  How can new countermeasures be designed for minimizing or preventing the consequences caused by these threats efficiently in practice?

    Part I of the thesis concentrates on the threats caused by "unwanted traffic", which includes Denial of Service (DoS) attacks and voice spam. They generate unwanted traffic to consume the resources and annoy users. Part II of this thesis explores unauthorized information disclosure in VoIP traffic. Confidential user data such as calling records, identity information, PIN code and data revealing a user's social networks might be disclosed or partially disclosed from VoIP traffic. We studied both threats and countermeasures by conducting experiments or using theoretical assessment. Part II also presents a survey research related to threats and countermeasures for anonymous VoIP communication.

  • 2920.
    Zhang, Ge
    et al.
    Karlstad University, Faculty of Economic Sciences, Communication and IT, Department of Computer Science.
    Fischer-Huebner, Simone
    Karlstad University, Faculty of Economic Sciences, Communication and IT, Department of Computer Science. Karlstad University, Faculty of Economic Sciences, Communication and IT, Centre for HumanIT.
    Detecting Near-Duplicate SPITs in Voice Mailboxes Using Hashes2011In: Proceedings of the 14th international conference on Information security ISC'11, Berlin: Springer Berlin/Heidelberg, 2011, p. 152-167Conference paper (Refereed)
    Abstract [en]

    Spam over Internet Telephony (SPIT) is a threat to the use of Voice of IP (VoIP) systems. One kind of SPIT can make unsolicited bulk calls to victims' voice mailboxes and then send them a prepared audio message. We detect this threat within a collaborative detection framework by comparing unknown VoIP flows with known SPIT samples since the same audio message generates VoIP flows with the same flow patterns (e.g., the sequence of packet sizes). In practice, however, these patterns are not exactly identical: (1) a VoIP flow may be unexpectedly altered by network impairments (e.g., delay jitter and packet loss); and (2) a sophisticated SPITer may dynamically generate each flow. For example, the SPITer employs a Text-To-Speech (TTS) synthesis engine to generate a speech audio instead of using a pre-recorded one. Thus, we measure the similarity among flows using local-sensitive hash algorithms. A close distance between the hash digest of flow x and a known SPIT suggests that flow x probably belongs the same bulk of the known SPIT. Finally, we also experimentally study the detection performance of the hash algorithms

  • 2921.
    Zhang, Ge
    et al.
    Karlstad University, Faculty of Economic Sciences, Communication and IT, Department of Computer Science.
    Fischer-Huebner, Simone
    Karlstad University, Faculty of Economic Sciences, Communication and IT, Department of Computer Science. Karlstad University, Faculty of Economic Sciences, Communication and IT, Centre for HumanIT.
    Timing Attacks on PIN Input in VoIP Networks: Short paper2011In: Detection of Intrusions and Malware, and Vulnerability Assessment: 8th International Conference, DIMVA 2011 / [ed] Holz, Thorsten; Bos, Herbert, Berlin: Springer Berlin/Heidelberg, 2011, p. 75-84Conference paper (Refereed)
    Abstract [en]

    To access automated voice services, Voice over IP (VoIP) users sometimes are required to provide their Personal Identification Numbers (PIN) for authentication. Therefore when they enter PINs, their user-agents generate packets for each key pressed and send them immediately over the networks. This paper shows that a malicious intermediary can recover the inter-keystroke time delay for each PIN input even if the standard encryption mechanism has been applied. The inter-keystroke delay can leak information of what has been typed: Our experiments show that the average search space of a brute force attack on PIN can be reduced by around 80%.

  • 2922.
    Zhang, Ge
    et al.
    Karlstad University, Faculty of Economic Sciences, Communication and IT, Department of Computer Science.
    Rebahi, Yacine
    Side effects of identity management in SIP VoIP environment2011In: Information Security Technical Report, ISSN 1363-4127, Vol. 16, no 1, p. 29-35Article in journal (Refereed)
    Abstract [en]

    In this article, we summarize the security threats targeting SIP proxy servers or other infrastructures in NGN by misusing a specific signaling authentication mechanism, which has been proposed in RFC 4474 (Peterson and Jennings, 2006). This mechanism is designed to authenticate inter-domain SIP requests based on domain certificates to prevent identity theft. Nevertheless, despite its contribution, this protection raises some “side effects”, that actually lead to new vulnerabilities in both the availability and confidentiality of SIP services. We provide an overview of different attack possibilities and explain them in more detail, including attacks utilizing algorithm complexity, certificates storage, and certificates distribution. We also suggest some alternative design to prevent or reduce the attacks. SIP, VoIP, NGN, Authentication, Denial of Service, Timing attack.

  • 2923.
    Zhang, Guoqiang
    KTH, School of Electrical Engineering (EES), Sound and Image Processing.
    On the rate region of the vector gaussian one-helper distributed source-coding problem2011In: 2011 DATA COMPRESSION CONFERENCE (DCC), 2011, p. 263-272Conference paper (Refereed)
    Abstract [en]

    In this paper we consider the rate region of the vector Gaussian one-helper distributed source coding problem. In particular, we derive optimality conditions under which a weighted sum rate is minimum by using a contradiction-based argument. When the sources are specified to be scalar, the optimality conditions can always be constructed for any weighted sum rate. In the derivation of the optimality conditions, we introduce a new concept of "source enhancement", which can be viewed as a dual to the well-known "channel enhancement" technique. In particular, source enhancement refers to the operation of increasing the covariance matrix of a Gaussian source in a partial ordering sense. This new technique makes the derivation of the optimality conditions straightforward.

  • 2924.
    Zhang, Heng
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Systems and Technology.
    Efficient database management based on complex association rules2017Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The large amount of data accumulated by applications is stored in a database. Because of the large amount, name conflicts or missing values sometimes occur. This prevents certain types of analysis. In this work, we solve the name conflict problem by comparing the similarity of the data, and changing the test data into the form of a given template dataset. Studies on data use many methods to discover knowledge from a given dataset. One popular method is association rules mining, which can find associations between items. This study unifies the incomplete data based on association rules. However, most rules based on traditional association rules mining are item-to-item rules, which is a less than perfect solution to the problem. The data recovery system is based on complex association rules able to find two more types of association rules, prefix pattern-to-item, and suffix pattern-to-item rules. Using complex association rules, several missing values are filled in. In order to find the frequent prefixes and frequent suffixes, this system used FP-tree to reduce the time, cost and redundancy. The segment phrases method can also be used for this system, which is a method based on the viscosity of two words to split a sentence into several phrases. Additionally, methods like data compression and hash map were used to speed up the search.

  • 2925.
    Zhang, Huimin
    et al.
    School of Electro-Mechanical Engineering, Xidian University.
    Feng, Lei
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Mechatronics.
    Wu, Naiqi
    Institute of Systems Engineering, Macau University of Science and Technology.
    Li, Zhiwu
    School of Electro-Mechanical Engineering, Xidian University.
    Integration of Learning-Based Testing and Supervisory Control for Requirements Conformance of Black-Box Reactive Systems2017In: IEEE Transactions on Automation Science and Engineering, ISSN 1545-5955, E-ISSN 1558-3783Article in journal (Refereed)
    Abstract [en]

    A fundamental requirement of the supervisory control theory (SCT) of discrete-event systems is a finite automaton model of the plant. The requirement does not hold for black-box systems whose source code and logical model are not accessible. To apply SCT to black-box systems, we integrate automaton learning technology with SCT and apply the new method to improve the requirements conformance of software reuse. If the reused software component does not satisfy a requirement, the method adds a supervisor component to prevent the black-box system from reaching ''faulty sections.'' The method employs learning-based testing (LBT) to verify whether the reused software meets all requirements in the new context. LBT generates a large number of test cases and iteratively constructs an automaton model of the system under test. If the system fails the test, the learned model is applied as the plant model for control synthesis using SCT. Then, the supervisor is implemented as an executable program to monitor and control the system to follow the requirement. Finally, the integrated system, including the supervisory program and the reused component, is tested by LBT to assure the satisfiability of the requirement. This paper makes two contributions. First, we innovatively integrate LBT and SCT for the control synthesis of black-box reactive systems. Second, software component reuse is still possible even if it does not satisfy user requirements at the outset.

  • 2926.
    Zhang, Minghui
    et al.
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Industrial Development, IT and Land Management.
    Su, Lian
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Industrial Development, IT and Land Management.
    How Can Digital Games be Applied in Education?: A Digital Education Game for introducing university to new students2013Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    In order to introduce the environment of the University of Gävle to the new students, an efficient way is needed. Among many different methods of helping new students get familiar with university, a Digital Education Game could be a good option. The aim of this research is to test if new students can learn more about University of Gävle when they are learning through a Digital Education Game. This research was mainly based on five methods. Before creating the game, a theoretical framework was built in the beginning, and then interviews and surveys were performed to get useful information. Next, a Digital Education Game was created through the platform e-Adventure. Finally, evaluations of this game were performed. The findings of this research were that according to the result of evaluating surveys, after players played this game, they were able to provide more correct answers than before. The conclusion could be drawn from this research was that new students could learn more about University of Gävle by playing a Digital Education Game.

  • 2927.
    Zhang, Silun
    et al.
    KTH, School of Engineering Sciences (SCI), Mathematics (Dept.), Optimization and Systems Theory. Harbin Institute of Technology, China.
    He, F.
    Yao, Y.
    Hu, Xiaoming
    KTH, School of Engineering Sciences (SCI), Mathematics (Dept.), Optimization and Systems Theory.
    Spherical formation of regular tetrahedra2017In: 2017 36th Chinese Control Conference, CCC, IEEE Computer Society, 2017, p. 1317-1322, article id 8027533Conference paper (Refereed)
    Abstract [en]

    In this paper, we study the problem of tracking and encircling a moving target by agents in the 3-dimensional space. Specifically, a group of agents are driven to a regular tetrahedron formation on a spherical surface and simultaneously keep the center of this spherical formation coinciding with the target to be tracked. In the proposed method, to avoid the singularity caused by spherical parameterisations in control, we directly consider the spherical formation in space S2. Besides, the protocol proposed does not contain any information of the desired formation beforehand. Rather the constructed formation pattern is attributed to the properties of space S2 and the inter-agent topology.

  • 2928. Zhang, Weiqing
    et al.
    Møller-Pedersen, Birger
    Biehl, Matthias
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Mechatronics.
    A light-weight tool integration approach: From a tool integration model to OSLC integration services2012In: ICSOFT 2012 - Proceedings of the 7th International Conference on Software Paradigm Trends, 2012, p. 137-146Conference paper (Refereed)
    Abstract [en]

    Existing tool integration approaches integrate various tools directly through tool proprietary APIs. This kind of integration lacks standardization and are different case by case. Integration based upon common tool metamodels also turns to be too complicated and hard to maintain. In this paper we provide an approach which integrates tools based on a combination of tool metamodels and an integration model. Tool element representatives (Artifacts) are defined to make integrations more standardized and flexible compared to direct tool APIs. The approach links the tool integration model to the various tool metamodels, and provides mechanism by which the common integration properties and the various tool metamodels are related. An industrial case study has been performed to validate the approach with both scenarios of traceability and exchange of data based upon common data definitions.

  • 2929.
    Zhang, Ying
    et al.
    Ericsson AB.
    Arvidsson, Åke
    Ericsson AB.
    Understanding the characteristics of cellular data traffic2012In: CellNet 2012 / [ed] Li Erran Li och Morley Mao Zhuoqing, Association for Computing Machinery (ACM), 2012Conference paper (Refereed)
    Abstract [en]

    Because of rapidly growing subscriber populations, advances in cellular communication technology, increasingly capable user terminals, and the expanding range of mobile applications, cellular networks have experienced a significant increase in data traffic, the dominant part of which is carried by the http protocol. Understanding the characteristics of this traffic is important for network design, traffic modeling, resource planning and network control. In this study we present a comprehensive characterization study of mobile http-based traffic using packet level traces collected in a large cellular network. We analyze the traffic using metrics at packet level, flow level and session level. For each metric, we conduct a comparison between traffic from different applications, as well as comparison to traffic in a wired network. Finally, we discuss the implications of our findings for better resource utilization in cellular infrastructures.

  • 2930.
    Zhang, Ying
    et al.
    USA.
    Arvidsson, Åke
    Ericsson AB.
    Siekkinen, Matti
    Finland.
    Urvoy-Keller, Guillaume
    Frankrike.
    Understanding HTTP flow rates in cellular networks2014In: Networking 2014 / [ed] Bjarne Helvik, Deep Medhi och Bin Liu, IFIP , 2014Conference paper (Refereed)
    Abstract [en]

    Data traffic in cellular networks increased tremendously over the past few years and this growth is predicted to continue over the next few years. Due to differences in access technology and user behavior, the characteristics of cellular traffic can differ from existing results for wireline traffic. In this study we focus on understanding the flow rates and on the relationship between the rates and other flow properties by analyzing packet level traces collected in a large cellular network. To understand the limiting factors of the flow rates, we further analyze the underlying causes behind the observed rates, e.g.,network congestion, access link or end host configuration. Our study extends other related work by conducting the analysis from a unique dimension, the comparison with traffic in wired networks, to reveal the unique properties of cellular traffic. We find that they differ in variability and in the dominant rate limiting factors.

  • 2931.
    Zhang, Yingfeng
    et al.
    Key Laboratory of Contemporary Design and Integrated Manufacturing Technology, Ministry of Education, Northwestern Polytechnical University, Shaanx, China / Department of Industrial Engineering, Northwestern Polytechnical University, Xi’an, China.
    Zhang, Geng
    Key Laboratory of Contemporary Design and Integrated Manufacturing Technology, Ministry of Education, Northwestern Polytechnical University, Shaanx, China.
    Liu, Yang
    Department of Production, University of Vaasa, Vaasa, Finland.
    Hu, Di
    Key Laboratory of Contemporary Design and Integrated Manufacturing Technology, Ministry of Education, Northwestern Polytechnical University, Shaanx, China.
    Research on services encapsulation and virtualization access model of machine for cloud manufacturing2015In: Journal of Intelligent Manufacturing, ISSN 0956-5515, E-ISSN 1572-8145, p. 1-15Article in journal (Refereed)
    Abstract [en]

    Considering the new requirements of the services encapsulation and virtualization access of manufacturing resources for cloud manufacturing (CMfg), this paper presents a services encapsulation and virtualization access model for manufacturing machine by combining the Internet of Things techniques and cloud computing. Based on this model, some key enabling technologies, such as configuration of sensors, active sensing of real-time manufacturing information, services encapsulation, registration and publishing method are designed. By implementing the proposed services encapsulation and virtualization access model to manufacturing machine, the capability of the machine could be actively perceived, the production process is transparent and can be timely visited, and the virtualized machine could be accessed to CMfg platform through a loose coupling, ‘plug and play’ manner. The proposed model and methods will provide the real-time, accurate, value-added and useful manufacturing information for optimal configuration and scheduling of large-scale manufacturing resources in a CMfg environment.

  • 2932.
    Zhao, Yi
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Systems and Technology.
    Discovery of temporal association rules in multivariate time series2017Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    This thesis focuses on mining association rules on multivariate time series. Com-mon association rule mining algorithms can usually only be applied to transactional data, and a typical application is market basket analysis. If we want to mine temporal association rules on time series data, changes need to be made. During temporal association rule mining, the temporal ordering nature of data and the temporal interval between the left and right patterns of a rule need to be considered. This thesis reviews some mining methods for temporal association rule mining, and proposes two similar algorithms for the mining of frequent patterns in single and multivariate time series. Both algorithms are scalable and efficient. In addition, temporal association rules are generated from the patterns found. Finally, the usability and efficiency of the algorithms are demonstrated by evaluating the results.

  • 2933.
    Zhou, Jiale
    et al.
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Hänninen, Kaj
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Lu, Yue
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Lundqvist, Kristina
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Provenzano, Luciana
    A Hazard Domain Ontology for Preliminary Hazard Analysis in Reuse Scenarios2016Report (Other academic)
  • 2934.
    Zhou, Jiale
    et al.
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Hänninen, Kaj
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Lundqvist, Kristina
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    A Hazard Modeling Language for Safety-Critical Systems Based on the Hazard Ontology2017In: 43rd Euromicro Conference on Software Engineering and Advanced Applications SEAA'17, 2017, p. 301-304Conference paper (Refereed)
    Abstract [en]

    Preliminary hazard analysis (PHA) is a key safety-concerned activity, applied during the early stages of safety-critical systems development process, aiming to provide stakeholders with a general understanding of potential hazards. The identified hazards will be described and serve as a basis to further identify mitigation mechanisms in the subsequent development process. However, since various stakeholders will be involved in the identification process, a common understanding of the nature of hazards among stakeholders, such as what a hazard consists of and how to describe it without ambiguities, is of crucial importance to achieve the goal of PHA. In this work, we propose a hazard modeling language (HML) based on a hazard domain ontology, i.e., the Hazard Ontology, in order to facilitate the specification of identified hazards. In addition, we present an approach to the transformation from natural language hazard descriptions into the HML specification. Finally, an industrial PHA example is used to illustrate the usefulness of our work.

  • 2935.
    Zhou, Jiale
    et al.
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Hänninen, Kaj
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Lundqvist, Kristina
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Lu, Yue
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Provenzano, Luciana
    Bombardier Transportation AB, Sweden.
    Forsberg, Kristina
    Saab AB, Sweden.
    An Environment-Driven Ontological Approach to Requirements Elicitation for Safety-Critical Systems2015In: 23rd IEEE International Requirements Engineering Conference RE'15, 2015, p. 247-251Conference paper (Refereed)
    Abstract [en]

    The environment, where a safety critical system (SCS) operates, is an important source from which safety requirements of the SCS can originate. By treating the system under construction as a black box, the environment is typically documented as a number of assumptions, based on which a set of environmental safety requirements will be elicited. However, it is not a trivial task in practice to capture the environmental assumptions to elicit safety requirements. The lack of certain assumptions or too strict assumptions will either result in incomplete environmental safety requirements or waste many efforts on eliciting incorrect requirements. Moreover, the variety of operating environment for an SCS will further complicate the task, since the captured assumptions are at risk of invalidity, and consequently the elicited requirements need to be revisited to ensure safety has not been compromised by the change. This short paper presents an on-going work aiming to 1) systematically organize the knowledge of system operating environment and, 2) facilitate the elicitation of environmental safety requirements. We propose an ontological approach to achieve the objectives. In particular, we utilize conceptual ontologies to organize the environment knowledge in terms of relevant environment concepts, relations among them and axioms. Environmental assumptions are captured by instantiating the environment ontology. An ontological reasoning mechanism is also provided to support elicitation of safety requirements from the captured assumptions.

  • 2936.
    Zhou, Jiale
    et al.
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Hänninen, Kaj
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Lundqvist, Kristina
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Provenzano, Luciana
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    An Ontological Approach to Identify the Causes of Hazards for Safety-Critical SystemsIn: 2017 2nd International Conference on System Reliability and Safety ICSRS'17Conference paper (Refereed)
    Abstract [en]

    Preliminary hazard analysis (PHA) is a key safety-concerned technique, applied in early stages of safety critical systems development, aiming to provide stakeholders with a general understanding of potential hazards together with their causes. Various studies have asserted that most significant flaws in hazard analysis techniques are related to the omission of causes associated with the identified hazards. In addition, identified causes are sometimes described in too generic terms to provide useful guidance for subsequent activities. In this paper, we propose an approach to explore and identify the causes associated with the hazards from a PHA, aiming to improve the results of hazard causes identification in terms of completeness and usefulness. To achieve the goal, the proposed approach utilizes the hazard-related concepts and relations defined in a hazard domain ontology presented in our previous work. Furthermore, an application scenario of a train control system is used to evaluate our approach.

  • 2937.
    Zhou, Jiale
    et al.
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Hänninen, Kaj
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Lundqvist, Kristina
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Provenzano, Luciana
    Bombardier Transportation, Sweden.
    An Ontological Interpretation of the Hazard Concept for Safety-Critical Systems2017In: PROCEEDINGS OF THE 27TH EUROPEAN SAFETY AND RELIABILITY CONFERENCE (ESREL 2017), PORTOROZ , SLOVENIA, 18–22 JUNE 2017, 2017, p. 183-185Conference paper (Refereed)
    Abstract [en]

    The hazard concept has been extensively used in the literature and defined in an informal way, which serves as a guidance on identifying the potential hazards during the development of safety-critical systems. Intuitively, the definitions seem to be consistent and easy to understand. However, when we take a closer look at these definitions, ambiguities may arise, and real-world semantics need to be defined. In this work, we propose a hazard domain ontology, i.e., the Hazard Ontology (HO), to provide an ontological interpretation of hazard. To tackle the aforementioned issues, the HO is grounded in the Unified Foundational Ontology (UFO) to utilize the benefits provided by taking foundational concepts into account. Finally, we show some useful findings when we use the proposed ontology to analyze the hazard descriptions from an industrial passenger train project.

  • 2938.
    Zhou, Shuqiao
    et al.
    Tsinghua University.
    Yuan, Ruixi
    Tsinghua University.
    Dely, Peter
    Karlstad University, Faculty of Economic Sciences, Communication and IT, Department of Computer Science.
    Kassler, Andreas
    Karlstad University, Faculty of Economic Sciences, Communication and IT, Department of Computer Science.
    Mitigating Control Channel Saturation in the Dynamic Channel Assignment Protocol2011In: JCIT: Journal of Convergence Information Technology, ISSN 2233-9299, Vol. 6, no 6, p. 271-281Article in journal (Refereed)
    Abstract [en]

     Multi-channel MAC protocols that rely on a dedicated control channel (CC) for data channel reservation face the problem of control channel saturation. When the control channel becomes the bottleneck, data channels are not fully utilized and the spectrum allocated for the network is not used efficiently. For a popular dedicated control channel based multi-channel MAC protocol, the dynamic channel assignment protocol (DCA), we propose and compare two methods for mitigating control channel saturation. The first method is based on the ability of modern wireless cards to use different channel bandwidths. Increasing the bandwidth of the CC allows higher transmission rates and thereby relieves the saturation on the CC. The second method involves TXOP (Transmission Opportunity)-like burst-transmissions, where several date packets are transmitted using one reservation operation on the control channel. Network simulations and analysis show that, in an 802.11 based network, the bandwidth adaptation method yields a throughput improvement of around 30%. The TXOP mechanism performs much better and increases the throughput by a factor of 2 to 10, depending on the length of the data packets.

  • 2939.
    Zhu, Angela Yun
    et al.
    Department of Computer Science, Rice University Houston, TX 77005, USA.
    Inoue, Jun
    Department of Computer Science, Rice University Houston, TX 77005, USA.
    Peralta, Marisa Linnea
    Department of Computer Science, Rice University Houston, TX 77005, USA.
    Taha, Walid
    Department of Computer Science, Rice University Houston, TX 77005, USA.
    O’Malley, Marcia
    Department of Mechanical Engineering and Materials Science Rice University, Houston, TX 77005, USA.
    Powell, Dane
    Department of Mechanical Engineering and Materials Science Rice University, Houston, TX 77005, USA.
    Implementing Haptic Feedback Environments from High-level Descriptions2009In: Embedded Software and Systems, 2009. ICESS '09. International Conference on: proceedings, Los Alamitos, Calif.: IEEE Computer Society, 2009, p. 482-489Conference paper (Refereed)
    Abstract [en]

    Haptic feedback can be a critical component of virtual environments used in cognitive research, rehabilitation, military training, and entertainment. A limiting factor in the innovation and the acceptance of virtual environments with haptic feedback is the time and cost required tobuild them. This paper presents a development environmentcalled iAcumen that supports a new approach for programming such systems. This approach allows the developer todirectly express physical equations describing the underlying dynamics. By raising the level of abstraction for thedeveloper, we avoid many of the problems that limit the effectiveness of traditional approaches.

  • 2940.
    Zhu, Angela Yun
    et al.
    Department of Computer Science, Rice University Houston, Houston, TX, USA.
    Taha, Walid
    Department of Computer Science, Rice University Houston, Houston, TX, USA.
    Cartwright, Robert
    Department of Computer Science, Rice University Houston, Houston, TX, USA.
    Martel, Matthieu
    Laboratoire ELIAUS-DALI, Universit´e de Perpignan, Perpignan Cedex, France.
    Siek, Jeremy G.
    Department of Electrical and Computer Engineering University of Colorado, Boulder, USA.
    In Pursuit of Real Answers2009In: 2009 International Conference on Embedded Software and Systems: ICESS 2009 : proceedings, 25-27 May, 2009, Hangzhou, Zhejiang, P.R. China, Los Alamitos, Calif.: IEEE Press, 2009, p. 115-122Conference paper (Refereed)
    Abstract [en]

    Digital computers permeate our physical world. This phenomenon creates a pressing need for tools that help us understand a priori how digital computers can affect their physical environment. In principle, simulation can be a powerful tool for animating models of the world. Today, however, there is not a single simulation environment that comes with a guarantee that the results of the simulationare determined purely by a real-valued model and not by artifacts of the digitized implementation. As such, simulation with guaranteed fidelity does not yet exist. Towards addressing this problem, we offer an expository account of what is known about exact real arithmetic. We argue that this technology, which has roots that are over 200 years old, bears significant promise as offering exactly the right technology to build simulation environments with guaranteed fidelity. And while it has only been sparsely studied in this large span of time, there are reasons to believe that the time is right to accelerate research in this direction.

  • 2941.
    Zhu, Sainan
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information and Communication systems.
    Creating a NoSQL database for the Internet of Things: Creating a key-value store on the SensibleThings platform2015Independent thesis Advanced level (degree of Master (One Year)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Due to the requirements of the Web 2.0 applications and the relational databaseshave a limitation in horizontal scalability. NoSQL databases have become moreand more popular in recent years. However, it is not easy to select a databasethat is suitable for a specific use. This thesis describes the detailed design, im plementation and final performance evaluation of a key-value NoSQL databasefor the SensibleThings platform, which is an Internet of Things platform. Thethesis starts by comparing the different types of NoSQL databases to select themost appropriate one. During the implementation of the database, the algorithms for data partition, data access, replication, addition and removal ofnodes, failure detection and handling are dealt with. The final results for theload distribution and the performance evaluation are also presented in this pa per. At the end of the thesis, some problems and improvements that need betaken into consideration in the futures.

  • 2942.
    Ziegenbein, Tim
    Linköping University, Department of Computer and Information Science, Human-Centered systems.
    Designing HTML5 2D platformer for web cam based motion games2015Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Movement interaction in games has over the last years been a main subject in the area of game design and recent motion based interaction systems provide many improvements over earlier systems. Research has proven that motion based games provide several benefits over general games, they increase the players’ engagement level and may induce both mental and physical health benefits. Still, not much research has been conducted in the area of motion based platform games, even though the platform game genre is one of the most popular game genres. In this thesis, a case study is conducted in order to extract design principles and guidelines applicable for motion based platform games. The study includes implementation of a browser-based 2D platform game that uses the web camera to provide motion based interaction. One of the conclusions in this study indicates that many game features from ordinary platform games only require minor modifications to be applicable for motion based platform games.

  • 2943.
    Zimmerman, Marc
    et al.
    Massachusetts Institute of Technology, Cambridge, USA.
    Lundqvist, Kristina
    Massachusetts Institute of Technology, Cambridge, USA.
    Leveson, Nancy
    Massachusetts Institute of Technology, Cambridge, USA.
    Investigating the readability of state-based formal requirements specification languages2002In: Proc. 24th International Conference on Software Engineering ICSE02, 2002, p. 33-43, article id 7Conference paper (Other academic)
  • 2944.
    Zografos, Vasileios
    et al.
    Linköping University, Department of Electrical Engineering, Computer Vision. Linköping University, The Institute of Technology.
    Lenz, Reiner
    Linköping University, Department of Electrical Engineering, Computer Vision. Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, The Institute of Technology.
    Spatio-chromatic image content descriptors and their analysis using Extreme Value Theory2011In: Image analysis: 17th Scandinavian Conference, SCIA 2011, Ystad, Sweden, May 2011. Proceedings, Springer Berlin/Heidelberg, 2011, p. 579-591Conference paper (Refereed)
    Abstract [en]

    We use the theory of group representations to construct very fast image descriptors that split the vector space of local RGB distributions into small group-invariant subspaces. These descriptors are group theoretical generalizations of the Fourier Transform and can be computed with algorithms similar to the FFT. Because of their computational efficiency they are especially suitable for retrieval, recognition and classification in very large image datasets. We also show that the statistical properties of these descriptors are governed by the principles of the Extreme Value Theory (EVT). This enables us to work directly with parametric probability distribution models, which offer a much lower dimensionality and higher resolution and flexibility than explore the connection to EVT and analyse the characteristics of these descriptors from a probabilistic viewpoint with the help of large image databases.

  • 2945.
    Zografos, Vasileios
    et al.
    Linköping University, Department of Electrical Engineering, Computer Vision. Linköping University, The Institute of Technology.
    Nordberg, Klas
    Linköping University, Department of Electrical Engineering, Computer Vision. Linköping University, The Institute of Technology.
    Fast and accurate motion segmentation using linear combination of views2011In: BMVC 2011, 2011, p. 12.1-12.11Conference paper (Refereed)
    Abstract [en]

    We introduce a simple and efficient procedure for the segmentation of rigidly moving objects, imaged under an affine camera model. For this purpose we revisit the theory of "linear combination of views" (LCV), proposed by Ullman and Basri [20], which states that the set of 2d views of an object undergoing 3d rigid transformations, is embedded in a low-dimensional linear subspace that is spanned by a small number of basis views. Our work shows, that one may use this theory for motion segmentation, and cluster the trajectories of 3d objects using only two 2d basis views. We therefore propose a practical motion segmentation method, built around LCV, that is very simple to implement and use, and in addition is very fast, meaning it is well suited for real-time SfM and tracking applications. We have experimented on real image sequences, where we show good segmentation results, comparable to the state-of-the-art in literature. If we also consider computational complexity, our proposed method is one of the best performers in combined speed and accuracy. © 2011. The copyright of this document resides with its authors.

  • 2946.
    Zola, Enrica
    et al.
    Spain.
    Kassler, Andreas
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Mathematics and Computer Science. Karlstad University, Faculty of Arts and Social Sciences (starting 2013), Centre for HumanIT.
    Minimizing the impact of the handover for mobile users in WLAN: A study on performance optimization2016In: Computer Networks, ISSN 1389-1286, E-ISSN 1872-7069, Vol. 107, p. 292-303Article in journal (Refereed)
    Abstract [en]

    IEEE 802.11 based Wireless LANs are an important piece in today’s communication infrastructure in order to provide high speed wireless Internet access to static or quasi mobile users. For large WLAN deployments (i.e., Campus or enterprise WLAN), it is important to understand the impact of user mobility and handovers on the system performance. In this article, we have developed a performance model for a set of networked 802.11 based WLAN Access Points, which is based on a Mixed Integer Linear Program (MILP). The objective function tries simultaneously to maximize the total system rate while at the same time minimizing the number of handovers for a configurable handover signaling rate. Because of the conflicting nature of the two objective functions, such multi-objective optimization is difficult to explore. A detailed evaluation of the model using several scenarios involving both different numbers of static and mobile users shows that our formulation allows trading off those two objectives in a robust way. 

  • 2947.
    Zou, Zhuo
    KTH, School of Information and Communication Technology (ICT), Electronic Systems.
    Impulse Radio UWB for the Internet-of-Things: A Study on UHF/UWB Hybrid Solution2011Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    This dissertation investigates Ultra-Wideband (UWB) techniques for the next generation Radio Frequency Identification (RFID) towards the Internet-of-Things (IoT). In particular, an ultra-high frequency (UHF) wireless-powered UWB radio (UHF/UWB hybrid) with asymmetric links is explored from system architecture to circuit implementation.

    Context-aware, location-aware, and energy-aware computing for the IoT demands future micro-devices (e.g., RFID tags) with capabilities of sensing, processing, communication, and positioning, which can be integrated into everyday objects including paper documents, as well as food and pharmaceutical packages. To this end, reliable-operating and maintenance-free wireless networks with low-power and low-cost radio transceivers are essential. In this context, state-of-the-art passive RFID technologies provide limited data rate and positioning accuracy, whereas active radios suffer from high complexity and power-hungry transceivers. Impulse Radio UWB (IR-UWB) exhibits significant advantages that are expected to overcome these limitations. Wideband signals offer robust communications and high-precision positioning; duty-cycled operations allow link scalability; and baseband-like architecture facilitates extremely simple and low-power transmitters. However, the implementation of the IR-UWB receiver is still power-hungry and complex, and thus is unacceptable for self-powered or passive tags.

    To cope with μW level power budget in wireless-powered systems, this dissertation proposes an UHF/UWB hybrid radio architecture with asymmetric links. It combines the passive UHF RFID and the IR-UWB transmitter. In the downlink (reader-tag), the tag is powered and controlled by UHF signals as conventional passive UHF tags, whereas it uses an IR-UWB transmitter to send data for a short time at a high rate in the uplink (tag-reader). Such an innovative architecture takes advantage of UWB transmissions, while the tag avoids the complex UWB receiver by shifting the burden to the reader. A wireless-powered tag providing -18.5 dBm sensitivity UHF downlink and 10 Mb/s UWB uplink is implemented in 180 nm CMOS. At the reader side, a non-coherent energy detection IR-UWB receiver is designed to pair the tag. The receiver is featured by high energy-efficiency and flexibility that supports multi-mode operations. A novel synchronization scheme based on the energy offset is suggested. It allows fast synchronization between the reader and tags, without increasing the hardware complexity. Time-of-Arrival (TOA) estimation schemes are analyzed and developed for the reader, which enables tag localization. The receiver prototype is fabricated in 90 nm CMOS with 16.3 mW power consumption and -79 dBm sensitivity at 10 Mb/s data rate. The system concept is verified by the link measurement between the tag and the reader. Compared with current passive UHF RFID systems, the UHF/UWB hybrid solution provides an order of magnitude improvement in terms of the data rate and positioning accuracy brought by the IR-UWB uplink.

  • 2948.
    Åberg, Christian
    Mälardalen University, School of Innovation, Design and Engineering.
    Automated Deployment of Customer-Premises Equipment2016Independent thesis Basic level (professional degree), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Zero touch deployment tools perform installation and configuration of computer networking devices without human interaction. Modern zero touch deployment tools generally lack support for routers and are platform dependent. This forces Internet Service Providers to rely on manual node deployment methods when deploying Customer-Premise Equipment which is time consuming and error prone. This thesis investigates how the process of deploying Customer-Premises Equipment can be automated and optimized. State-of-the-art is discussed to point out requirements and possible improvements. Based on that, a tool is implemented performing deployment of Customer-Premises Equipment while minimizing manual intervention. As Internet Service Providers typically work with equipment from various vendors, multivendor support is implemented. This thesis studies common methods for initial Customer-Premises Equipment configuration. Request for Comments and Technical manuals are consulted regarding network protocols, zero touch deployment tools and router operating systems.

  • 2949.
    Åberg, Ludvig
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Systems and Technology.
    Parallelism within queue application2017Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The aim of this thesis was to modify an existing order queue application which was unable to execute orders in a queue in parallel which in turn could lead to a bad user experience due to the increased queue delay. The thesis proposes two queue structures to allow parallel execution within a queue. One of the two is selected for implemented in the modified order queue application. The implementation was carried out in Java EE and used different types of frameworks such as JPQL. Some parts of the order queue application had to be modified to be able to handle the new queue structure. New attributes that defines dependencies of the orders are used to find a suitable parent for each order in the queue. The queue structure was visualized making it possible to see the execution in real time, and a test server was implemented to test the queue structure. This resulted in a working prototype able to handle dependencies and parallel orders. The modified order queue application was performance measured and compared to the original order queue application. The measurement showed that the modified order queue application performed better than the original order queue application in terms of execution time below a certain number of queues. Future work includes optimizing the methods and queries in the implementation to increase the performance and to handle parallelism within the orders.

  • 2950.
    Åhlander, Gustav
    et al.
    Linnaeus University, Faculty of Technology, Department of Informatics.
    William, Andersson
    Linnaeus University, Faculty of Technology, Department of Informatics.
    En bild säger mer än tusen ord: En fallstudie om hur verksamhetsmodellering kan användas som stöd vid kravarbete i en outsourcad miljö.2016Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    This bachelor thesis deals with the subject of business process modelling in an outsourced environment. The communication process between two parties that are on either side of the globe can be problematic and affect the quality of the system requirements. The background of this study is that there is a lack of communication between these parties, which will eventuate in poor results.

     

    The purpose of this study is to find out whether it is possible to make use of business process modelling in an outsourced environment in order to increase the quality of system requirements by bringing the two parties closer together with help of a common language. A qualitative approach was used to interview relevant informants at Länsförsäkringar AB and its business units Länsförsäkringar Liv and Länsförsäkringar Bank.

     

    We have identified that it is not necessarily the system requirements that have a poor quality but how these system conveyed to the external supplier. Based on our data collection, we realized the great benefits of business process modelling as a means of communication in the system development, which can be a huge advantage in an outsourced environment. According to our study, it is certain that a business process modelling with mapped processes and flow charts can support communication as a common language because of the creation of processes and images instead of text.

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