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  • 16701.
    Zeljic, Aleksandar
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Wintersteiger, Christoph M.
    Rümmer, Philipp
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    An approximation framework for solvers and decision procedures2017In: Journal of automated reasoning, ISSN 0168-7433, E-ISSN 1573-0670, Vol. 58, no 1, 127-147 p.Article in journal (Refereed)
  • 16702.
    Zeljic, Aleksandar
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Wintersteiger, Christoph M.
    Microsoft Research Cambridge.
    Rümmer, Philipp
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Approximations for Model Construction2014In: Automated Reasoning, Springer, 2014, 344-359 p.Conference paper (Refereed)
    Abstract [en]

    We consider the problem of efficiently computing models for satisfiable constraints, in the presence of complex background theories such as floating-point arithmetic. Model construction has various applications, for instance the automatic generation of test inputs. It is well-known that naive encoding of constraints into simpler theories (for instance, bit-vectors or propositional logic) can lead to a drastic increase in size, and be unsatisfactory in terms of memory and runtime needed for model construction. We define a framework for systematic application of approximations in order to speed up model construction. Our method is more general than previous techniques in the sense that approximations that are neither under- nor over-approximations can be used, and shows promising results in practice.

  • 16703.
    Zeljic, Aleksandar
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Wintersteiger, Christoph M.
    Rümmer, Philipp
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Deciding bit-vector formulas with mcSAT2016In: Theory and Applications of Satisfiability Testing: SAT 2016, Springer, 2016, 249-266 p.Conference paper (Refereed)
  • 16704.
    Zellers, Margaret
    KTH, School of Computer Science and Communication (CSC), Speech, Music and Hearing, TMH, Speech Communication and Technology.
    Pitch and lengthening as cues to turn transition in Swedish2013In: Proceedings of Interspeech 2013, 2013, 248-252 p.Conference paper (Refereed)
    Abstract [en]

    In many cases of turn transition in conversation, a new speaker may respond to phonetic cues from the end of the prior turn, including variation in prosodic features such as pitch and final lengthening. Although consistent pitch and lengthening features are well-established for some languages at potential points of turn transition, this is not necessarily the case for Swedish. The current study uses a two-alternative forced choice task to investigate how variation in pitch contour and lengthening at the ends of syntactically complete turns can influence listeners’ expectations of turn hold or turn transition. Both lengthening and pitch contour features were found to influence listeners’ judgments about whether turn transition would occur, with shorter length and higher final pitch peaks associated with turn hold. Furthermore, listeners were more certain about their judgments when asked about turn-hold rather than turn-change, suggesting an imbalance in the strength of turn-hold versus turn-transition cues.

  • 16705.
    Zellers, Margaret
    Department of Language and Linguistic Science, University of York, York, UK .
    Prosodic variation for topic shift and other functions in local contrasts in conversation2013In: Phonetica, ISSN 0031-8388, E-ISSN 1423-0321, Vol. 69, no 4, 231-253 p.Article in journal (Refereed)
    Abstract [en]

    Speakers and listeners have been shown to use phonetic cues to help them in tracking the ongoing structure of conversational interaction, but fragmentation between qualitative and quantitative research means that the forms and functions of these cues have been given varying characterizations. The current study explores prosodic variation in contrastive structures in conversational data, using a combined methodology adopting aspects from both qualitative (conversation analysis) and quantitative (experimental phonetics/phonology) approaches. Statistical and conversation-analytical methods used together reveal relationships between prosodic variation and interactional function, such as variations in pitch range across adjacent turns being linked to the presence of 'stepwise' topic changes.

  • 16706.
    Zellers, Margaret
    et al.
    KTH, School of Computer Science and Communication (CSC), Speech, Music and Hearing, TMH, Speech Communication and Technology.
    House, David
    KTH, School of Computer Science and Communication (CSC), Speech, Music and Hearing, TMH, Speech Communication and Technology.
    Parallels between hand gestures and acoustic prosodic features in turn-taking2015In: 14th International Pragmatics Conference, Antwerp, Belgium, 2015, 454-455 p.Conference paper (Refereed)
  • 16707.
    Zeng, Haibo
    et al.
    Department of Electrical and Computer Engineering, Virginia Tech.
    Joshi, Prachi
    Department of Electrical and Computer Engineering, Virginia Tech.
    Thiele, Daniel
    Elektrobit Automotive GmbH.
    Diemer, Jonas
    Symtavision.
    Axer, Philip
    NXP Semiconductors.
    Ernst, Rolf
    Institut für Datentechnik und Kommunikationsnetze, Technische Universität Braunschweig.
    Eles, Petru
    Linköping University, Department of Computer and Information Science, Software and Systems. Linköping University, Faculty of Science & Engineering.
    Networked Real-Time Embedded Systems2017In: Handbook of Hardware/Software Codesign, Springer Netherlands, 2017, 1-40 p.Chapter in book (Refereed)
    Abstract [en]

    This chapter gives an overview on various real-time communication protocols, from the Controller Area Network (CAN) that was standardized over twenty years ago but is still popular, to the FlexRay protocol that provides strong predictability and fault tolerance, to the more recent Ethernet-based networks. The design of these protocols including their messaging mechanisms was driven by diversified requirements on bandwidth, real-time predictability, reliability, cost, etc. The chapter provides three examples of real-time communication protocols: CAN as an example of event-triggered communication, FlexRay as a heterogeneous protocol supporting both time-triggered and event-triggered communications, and different incarnations of Ethernet that provide desired temporal guarantees.

  • 16708.
    Zeng, Yingfu
    et al.
    Rice University, Houston, USA.
    Chad, Rose
    Rice University, Houston, USA.
    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, USA.
    Duracz, Adam
    Halmstad University, School of Information Technology, Halmstad Embedded and Intelligent Systems Research (EIS), Centre for Research on Embedded Systems (CERES).
    Atkinson, Kevin
    Rice University, Houston, USA.
    Philippsen, Roland
    Halmstad University, School of Information Technology, Halmstad Embedded and Intelligent Systems Research (EIS), CAISR - Center for Applied Intelligent Systems Research.
    Cartwright, Robert
    Rice University, Houston, USA.
    O'Malley, Marcia
    Rice University, Houston, USA.
    Modeling Electromechanical Aspects of Cyber-Physical Systems2016In: Journal of Software Engineering for Robotics, ISSN 2035-3928, E-ISSN 2035-3928, Vol. 7, no 1, 100-119 p.Article in journal (Refereed)
    Abstract [en]

    Model-based tools have the potential to significantly improve the process of developing novel cyber-physical systems (CPS). In this paper, we consider the question of what language features are needed to model such systems. We use a small, experimental hybrid systems modeling language to show how a number of basic and pervasive aspects of cyber-physical systems can be modeled concisely using the small set of language constructs. We then consider four, more complex, case studies from the domain of robotics. The first, a quadcopter, illustrates that these constructs can support the modeling of interesting systems. The second, a serial robot, provides a concrete example of why it is important to support static partial derivatives, namely, that it significantly improves the way models of rigid body dynamics can be expressed. The third, a linear solenoid actuator, illustrates the language’s ability to integrate multiphysics subsystems. The fourth and final, a compass gait biped, shows how a hybrid system with non-trivial dynamics is modeled. Through this analysis, the work establishes a strong connection between the engineering needs of the CPS domain and the language features that can address these needs. The study builds the case for why modeling languages can be improved by integrating several features, most notably, partial derivatives, differentiation without duplication, and support for equations. These features do not appear to be addressed in a satisfactory manner in mainstream modeling and simulation tools.

  • 16709.
    Zennaro, Marco
    et al.
    KTH, School of Information and Communication Technology (ICT), Communication: Services and Infrastucture, Telecommunication Systems Laboratory, TSLab.
    Bagula, Antoine
    Gascon, David
    Bielsa Noveleta, Alberto
    Planning and Deploying Long Distance Wireless Sensor Networks: The Integration of Simulation and Experimentation2010In: 9th International Conference on Ad-Hoc Networks and Wireless Univ Alberta, Edmonton, CANADA, AUG 20-22, 2010, 2010, Vol. 6288, 191-204 p.Conference paper (Other academic)
    Abstract [en]

    Wireless sensor networks allow unprecedented abilities to observe and understand large-scale, real-world phenomena at a fine spatial-temporal resolution. Their application in Developing Countries is even more interesting: they can help solve problems that affect communities. One of the limitations of current wireless sensors is the communication range, with most devices having 100 meters as maximum range. In contrast, many applications require long-range wireless sensor network where nodes are separated by large distances, giving the advantage of being able to monitor a large geographic area. In this paper we will present the results of an integrated approach combining a planning step using simulations and an experimental step carried out using off-the-shelf equipment over distances ranging from 600m to 12km. The results reveal that the simulation results agree with experimentation and show that long distance wireless sensor networks (LDWSN) are possible and that the quality of these links is high. Finally, we discuss the relative efficiency of our solution in terms of range compared to other wireless sensor networks.

  • 16710.
    Zepernick, Hans-Jürgen
    et al.
    Blekinge Institute of Technology, School of Engineering, Department of Signal Processing.
    Fiedler, Markus
    Blekinge Institute of Technology, School of Engineering, Department of Telecommunication Systems.
    Lundberg, Lars
    Blekinge Institute of Technology, School of Engineering, Department of Systems and Software Engineering.
    Pettersson, Mats
    Blekinge Institute of Technology, School of Engineering, Department of Signal Processing.
    Quality of Experience Based Cross-Layer Design of Mobile Video Systems2008Conference paper (Refereed)
    Abstract [en]

    This paper introduces and discusses quality of experience based cross-layer design of mobile video systems as a means of providing technologies for jointly analyzing, adopting, and optimizing system quality. The many benefits of our novel approaches over traditional concepts will range from efficient video processing techniques over advanced real-time scheduling algorithms, to networking and service level management techniques. This will lead to better service quality and resource utilization in mobile video systems.

  • 16711.
    Zetterlund, Marie
    University of Skövde, Department of Computer Science.
    Intranät: en belysning av eventuella problem och åtgärder1998Independent thesis Basic level (degree of Bachelor)Student thesis
    Abstract [sv]

    I detta arbete har jag valt att intervjua representanter från 5 större företag som är ledande inom sitt verksamhetsområde. Syftet med denna rapport är att belysa intranätansvarigas syn på de problem och risker som kan uppkomma med intranät som elektronisk informationsmedium. De risker och problem som jag har tittat på är om det finns en risk för en användare att missa relevant information, få tillgång till för mycket information samt utsättas för för mycket information i ett intranät. Information har samlats in via intervjuer och litteraturstudier.

    Undersökningens slutsatser handlar i stort om de åtgärder som ett företag kan vidta för att förhindra att eventuella risker och problem skall uppkomma. Den viktigaste åtgärden är utbildning av den vanliga användaren. Rapporten avslutas med en diskussion kring ämnet samt några eget komponerade riktlinjer för införande av ett intranät i en verksamhet.

  • 16712.
    Zhabelova, G.
    et al.
    University of Auckland.
    Patil, Sandeep
    University of Auckland.
    Yang, C-W
    University of Auckland.
    Vyatkin, Valeriy
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Computer Science.
    Smart Grid applications with IEC 61499 reference architecture2013In: Proceedings of the 11th IEEE Conference on Industrial Informatics (INDIN 2013): Bochum; Germany; 29 July 2013 through 31 July 2013, IEEE Communications Society, 2013, 458-463 p., 6622928Conference paper (Refereed)
    Abstract [en]

    This paper presents implementation of the Distributed Grid Intelligence (DGI) applications such as Intelligent Fault Management and Load Balancing using IEC61499 reference architecture. This enables system level design of distributed applications with a direct pathway to deployment to hardware. The use of IEC 61499 improves scalability, re-configurability and maintainability of automation software. Both applications were verified using co-simulation approach: control and power system simulated on PCs, and power system simulation on a PC networked with the number of distributed hardware running control algorithm. Both DGI applications were deployed to commercial programmable automation devices and embedded controllers. The use of IEC 61499 facilitates deployment of hardware independent function block model to the variety of compliant hardware. The paper also discusses distributed SCADA concept with IEC61499 implemented with the so-called Composite Automation Type (CAT) function blocks which combine functional and visual components. These blocks are used to implement human-machine interface of the FREEDM Smart Grid demonstrator reacting on plugging and unplugging of energy resources

  • 16713.
    Zhabelova, G.
    et al.
    University of Auckland.
    Vyatkin, Valeriy
    Multiagent smart grid automation architecture based on IEC 61850/61499 intelligent logical nodes2012In: IEEE transactions on industrial electronics (1982. Print), ISSN 0278-0046, E-ISSN 1557-9948, Vol. 59, no 5, 2351-2362 p.Article in journal (Refereed)
    Abstract [en]

    Universal, intelligent, and multifunctional devices controlling power distribution and measurement will become the enabling technology of the Smart Grid ICT. In this paper, we report on a novel automation architecture which supports distributed multiagent intelligence, interoperability, and configurability and enables efficient simulation of distributed automation systems. The solution is based on the combination of IEC 61850 object-based modeling and interoperable communication with IEC 61499 function block executable specification. Using the developed simulation environment, we demonstrate the possibility of multiagent control to achieve self-healing grid through collaborative fault location and power restoration.

  • 16714.
    Zhabelova, Gulnara
    et al.
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Computer Science.
    Vyatkin, Valeriy
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Computer Science.
    Towards a Design Methodology for Agent-Based Automation of Smart Grid2015In: Industrial Applications of Holonic and Multi-Agent Systems: 7th International Conference, HoloMAS 2015, Valencia, Spain, September 2-3, 2015, Proceedings / [ed] Vladimír Mařík ; Arnd Schirrmann; Damien Trentesaux ; Pavel Vrba, New York: Encyclopedia of Global Archaeology/Springer Verlag, 2015, 181-194 p.Conference paper (Refereed)
    Abstract [en]

    This paper proposes an agent-oriented design methodology specific to power system automation domain. The existing agent-oriented methodologies have some deficiencies when applied in industrial automation. Besides, there is lack of models, methods and guidelines for their systematic application. The proposed methodology combines familiar to domain engineer design process of the IEC 61850 standard and design flow of agent-oriented methodologies. The resultant agent-based system is modelled and implemented with IEC 61499. The transformation of IEC 61850 models into the IEC 61499 solution models is guided by the set of rules and supported by automated transformation tool. The methodology has a set of models, their transformation methods and well defined steps that enable systematic design of the agent-based solutions for power system. The methodology is exemplified here on a Smart Grid protection application

  • 16715.
    Zhabelova, Gulnara
    et al.
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Computer Science.
    Vyatkin, Valeriy
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Computer Science.
    Towards software metrics for evaluating quality of IEC 61499 automation software2015In: Proceedings of 2015 IEEE 20th International Conference on Emerging Technologies & Factory Automation (ETFA 2015): Luxembourg, 8-11 Sept. 2015, Piscataway, NJ: IEEE Communications Society, 2015, 7301502Conference paper (Refereed)
    Abstract [en]

    The quality of the software has an increasing impact on the performance, operation and ultimately the cost of industrial automation systems. Software metrics are necessary to assess the quality and to identify modules that impact cost of testing and maintenance. There is a number of software metrics available within a software engineering domain. However, there is a gap when it comes to evaluating IEC 61499 automation software. It is a challenging task too. IEC 61499 architecture embraces several software development techniques such as imperative languages, state machines and object oriented programming. This paper proposes the method for calculating metrics for IEC 61499 function blocks. These metrics were used to analyze power system protection software. Metrics confirmed expected results and reasonably described quality of software modules. With further improvement and expansion of the proposed set of metrics, it will be possible to accurately analyze and therefore improve automation software design and reduce cost.

  • 16716.
    Zhabelova, Gulnara
    et al.
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Computer Science.
    Vyatkin, Valeriy
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Computer Science.
    Dubinin, Victor N.
    University of Auckland, Penza State University, Department of Computer Science, University of Penza.
    Decision making for industrial agents in Smart Grid applications2015In: IECON 2014: 40th Annual Conference of the IEEE Industrial Electronics Society, Dallas, TX, USA , Oct. 29 2014 - Nov. 1 2014, Piscataway, NJ: IEEE Communications Society, 2015, 3584-3590 p.Conference paper (Refereed)
    Abstract [en]

    Agent technology in the power system domain isthe realm of theory and laboratory simulation. Agent-basedsystems, due to their complexity of concept and design, mayappear difficult to implement and maintain, and hence moreexpensive, which is a prohibiting factor against using the newtechnology. Designing a decision-making system for an agent isone of the most complex tasks in the development of agent-basedsystems. Designing a decision-making system enabling proactivebehaviours while maintaining reasonable complexity is achallenge. This paper proposes an deliberative decision makingsystem for an industrial agent which allows pro-active behaviourof the agent while maintaining reasonable complexity. It employsa combination of practical and procedural reasoning principles.The formal definition of the proposed deliberative layer isderived in the paper. The procedural reasoning is based on IEC61850 Logical Node concept and implemented with IEC 61499reference architecture. The proposed agent architecture isdemonstrated on the Fault Location Isolation and SupplyRestoration application and validated via so-simulation withMatlab model of the sample distribution network.

  • 16717.
    Zhabelova, Gulnara
    et al.
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Computer Science.
    Vyatkin, Valeriy
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Computer Science.
    Dubinin, Victor N.
    Penza State University, Department of Computer Science, University of Penza.
    Towards industrially usable agent technology for Smart Grid automation2015In: IEEE transactions on industrial electronics (1982. Print), ISSN 0278-0046, E-ISSN 1557-9948, Vol. 62, no 4, 2629-2641 p.Article in journal (Refereed)
    Abstract [en]

    This work is aimed at facilitating industrial adoption of agent technology. The paper proposes the hybrid agent architecture specific to the power system automation domain. The architecture builds on the Logical Node concept of IEC 61850 and comprises of a deliberative and a reactive layers; combining advantages of both. By relying on the underlined industrial standards IEC 61850 and IEC 61499, the architecture ensures practical applicability and captures domain specific concepts in the agent-based system design. Developed agentbased system was validated in the co-simulation framework. The architecture provides for rapid system development, reducing the software development life cycle. The benefits are in trace-ability of the software requirements, re-use of software components, ease of re-design, and direct deployment of the system model.

  • 16718.
    Zhabelova, Gulnara
    et al.
    Department of Electrical and Computer Engineering, University of Auckland.
    Vyatkin, Valeriy
    Dept. of Electr. & Comput. Eng., Univ. of Auckland.
    Zhang, Ziang
    Department of Electrical and Computer Engineering, North Carolina State University, Raleigh.
    Chow, Mo-Yuen
    Department of Electrical and Computer Engineering, North Carolina State University, Raleigh.
    Agent-based distributed consensus algorithm for decentralized economic dispatch in Smart Grid2013In: IECON 2013: 39th Annual Conference of the IEEE Industrial Electronics Society, Piscataway, NJ: IEEE Communications Society, 2013, 1968-1973 p.Conference paper (Refereed)
    Abstract [en]

    The agent based solutions are successfully applied in research and have impressive results. However, at the present, the agent technology is the realm of theory and laboratory simulation. The paper presents an attempt to bridge the gap. To facilitate migration of agent technology to the field, we propose to apply industrial standards such as IEC 61499 to design and implement the agent based algorithms. IEC 61499 is reference architecture for development of distributed systems. As an example of agent based solution to power system problem we consider Incremental Cost Consensus (ICC) algorithm for solving economic dispatch problem. The original system was simulated in Matlab. The agent based 5 node system was developed using IEC 61499 and deployed to 5 industrial controllers, then tested. With the proposed approach the agent algorithms can be designed, tested and deployed within one framework without the overhead of re-coding the solution for different stages. The proposed approach enables directly executable agent solutions and paves the way to the industrial adoption of the agent technology in power system domain.

  • 16719.
    Zhabelova, Gulnara
    et al.
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Computer Science.
    Yang, Chen-Wei
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Computer Science.
    Patil, Sandeep
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Computer Science.
    Pang, Cheng
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Computer Science.
    Yan, Jeffrey
    Department of Electrical and Computer System Engineering, University of Auckland.
    Shalyto, Anatoly
    ITMO University.
    Vyatkin, Valeriy
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Computer Science.
    Cyber-physical components for heterogeneous modeling, validation and implementation of smart grid intelligence2014In: 12th IEEE Conference on Industrial Informatics (INDIN 2014): Porto Alegre, Brazil, 27 - 30 July 2014, Piscataway, NJ: IEEE Communications Society, 2014, 411-417 p.Conference paper (Refereed)
    Abstract [en]

    This paper presents a practical framework to bring the cyber-physical block diagram models, such as Ptolemy, to the practice of industrial automation. Cyber-Physical Component (CPC) architecture is suggested. CPC aims at the improvement of design, verification and validation practices in automation of Smart Grid. IEC 61499 standard is used as a basis for this architecture. This architecture addresses several design software and system engineering challenges: right equilibrium between abstract representation and “executability” and round-trip engineering. An CPC exhibit such properties as portability, interoperability and configurability thanks to the reliance on open standards. The use of time stamp based execution paradigm adds determinism and predictability at the run-time.

  • 16720.
    Zhabelova, Gulnara
    et al.
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Computer Science.
    Yang, Chen-Wei
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Computer Science.
    Vyatkin, Valeriy
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Computer Science.
    SysGrid: IEC 61850/IEC 61499 based engineering process for Smart Grid automation design2013In: 11th IEEE International Conference on Industrial Informatics, INDIN 2013: Bochum, Germany 29 July - 31 July 2013, Piscataway, NJ: IEEE Communications Society, 2013, 364-369 p.Conference paper (Refereed)
    Abstract [en]

    The paper proposes a novel computer-aided model-based system engineering process for Smart Gird applications. The process is supported by the SysGrid tool that plays the roles of system configurator and device configurator. The design process starts with single line diagrams which are automatically transformed to executable function block specifications. The process is based on the Smart Grid control architecture that is a heterogeneous network of controllers communicating in a peer to peer manner. This “artificial nervous system” of the Smart Grid will be capable of self-healing and dynamic adaptation to renewable generation and ever-changing loads. The tool supports system-level design of automation logic in the form of function block networks with compliancy to IEC 61499. The capabilities of SysGrid are demonstrated through the process of designing a distributed protection application.

  • 16721.
    Zhabelova, Gulnara
    et al.
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Computer Science.
    Yang, Chen-Wei
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Computer Science.
    Vyatkin, Valeriy
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Computer Science.
    Etherden, Nicholas
    Vattenfall AB, Stockholm.
    Christoffersson, Lars
    IETV AB, Gallstad.
    Open Architecture for Cost Effective Protection and Control of Power Distribution Networks2016In: IEEE International Conference on Smart Grid Communications (SmartGridComm) 2016, Piscataway, NJ, 2016, 729-735 p., 7778848Conference paper (Refereed)
    Abstract [en]

    The paper aims at demonstrating the feasibility of an execution platform that is capable of performing protection and control functions from various vendors in a controlled manner. This will reduce vendor dependency enabling utilities to standardize hardware while implementing complex protection schemes from multiple vendors at reduced cost. The paper develops protection system including earth, differential and overcurrent protection functions from different vendors integrated in one hardware using IEC 61499 open reference architecture. IEC 61499 enables efficient and flexible design and implementation of the distributed automation systems. Selected substation is modelled in Matlab Simulink. Developed protection scheme is performed by programmable automation controller (PAC) and validated by connecting it to the simulation model of the substation. The protection scheme satisfied all functional requirements. At present, authors are working on validating its timing properties.

  • 16722.
    Zhabelova, Gulnara
    et al.
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Computer Science.
    Yavarian, Alireza
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Computer Science.
    Vyatkin, Valeriy
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Computer Science.
    Data center power dynamics within the settings of regional power grid2015In: Proceedings of 2015 IEEE 20th International Conference on Emerging Technologies & Factory Automation (ETFA 2015): Luxembourg, 8-11 Sept. 2015, Piscataway, NJ: IEEE Communications Society, 2015, 7301633Conference paper (Refereed)
    Abstract [en]

    Data centers have grown to become big energy cconsumers. At this scale of power consumption, data centers play cconsiderable role in electric networks operation. However, being ca relatively new industrial scale consumer, data center requires cmore careful consideration and research to uncover its specifics cand better understand its requirements; and investigate data ccenter's impact on regional grid. This paper reports on the work cin progress and at this stage details an effort to understand the cimpact of dynamic server load of a data center on its power cinfrastructure and further on the grid; the effects of transient cfaults in power grid on performance of a data center. This will chelp regional grid operators to improve power balancing within cthe network to maintaining network stability avoiding failures cand blackouts. The results of this work will be used in developing cdynamic power balancing strategy for a smart grid containing clarge data centers.

  • 16723.
    Zhabelova, Gulnara
    et al.
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Computer Science.
    Yavarian, Alireza
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Computer Science.
    Vyatkin, Valeriy
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Computer Science.
    Huang, Alex
    Department of Electrical and Computer Engineering, North Carolina State University, Raleigh, NC.
    Data center energy efficiency and power quality: An alternative approach with solid state transformer2016In: Annual Conference of the IEEE Industrial Electronics Society, IECON 2015: Yokohama, Japan, 9-12 Nov. 2015, Piscataway, NJ: IEEE Communications Society, 2016, 1294-1300 p., 7392279Conference paper (Refereed)
    Abstract [en]

    Data center evolved to become large power consumers. Its supporting infrastructure, such as cooling and power distribution, consumes resources e.g. electric power and money. In fact, most money is spent on power conditioning and cooling systems. Therefore, the efficiency of data center and power quality are important topics and can be addressed by careful design. There is a need for research into application of innovative design and state-of-the-art technology for optimizing power supply in data centers. The paper investigates potential of a state-of-the-art technology such as solid state transformer (SST). The simulation proves that SST has potential to improve operational efficiency. SST shows better control of voltage, current and reactive power of the facility, eliminating need for additional devices such as power conditioners and reducing power loss. These results lead to the next stage of the project that involves developing an optimal data center design with SST and investigating data center potential in demand response applications.

  • 16724.
    Zhai, Shumin
    et al.
    IBM Research, Almaden Center, San Jose, CA.
    Kristensson, Per-Ola
    Linköping University, Department of Computer and Information Science, MDALAB - Human Computer Interfaces. Linköping University, The Institute of Technology.
    Shorthand writing on stylus keyboard2003In: Proceeding CHI '03 Proceedings of the SIGCHI Conference on Human Factors in Computing Systems, New York: ACM Press , 2003, 97-104 p.Conference paper (Refereed)
    Abstract [en]

    We propose a method for computer-based speed writing, SHARK (shorthand aided rapid keyboarding), which augments stylus keyboarding with shorthand gesturing. SHARK defines a shorthand symbol for each word according to its movement pattern on an optimized stylus keyboard. The key principles for the SHARK design include high efficiency stemmed from layout optimization, duality of gesturing and stylus tapping, scale and location independent writing, Zipf's law, and skill transfer from tapping to shorthand writing due to pattern consistency. We developed a SHARK system based on a classic handwriting recognition algorithm. A user study demonstrated the feasibility of the SHARK method.

  • 16725.
    Zhai, Shumin
    et al.
    IBM Almaden Research Center.
    Kristensson, Per-Ola
    Linköping University, The Institute of Technology. Linköping University, Department of Computer and Information Science, ASLAB - Application Systems Laboratory.
    Smith, Barton
    IBM Almaden Research Center.
    In search of effective text input interfaces for off the desktop computing2004In: Human Computer Interaction Consortium Winter Workshop,2004, 2004Conference paper (Refereed)
  • 16726.
    Zhang, Bailing
    et al.
    Xi’an Jiaotong-Liverpool University, Suzhou, 215123, P.R.China.
    Pham, Tuan D
    School of Engineering and Information Technology, The University of New South Wales.
    Phenotype recognition with combined features and random subspace classifier ensemble2011In: BMC Bioinformatics, ISSN 1471-2105, E-ISSN 1471-2105, Vol. 12, no 1, 1-14 p.Article in journal (Refereed)
    Abstract [en]

    Automated, image based high-content screening is a fundamental tool for discovery in biological science. Modern robotic fluorescence microscopes are able to capture thousands of images from massively parallel experiments such as RNA interference (RNAi) or small-molecule screens. As such, efficient computational methods are required for automatic cellular phenotype identification capable of dealing with large image data sets. In this paper we investigated an efficient method for the extraction of quantitative features from images by combining second order statistics, or Haralick features, with curvelet transform. A random subspace based classifier ensemble with multiple layer perceptron (MLP) as the base classifier was then exploited for classification. Haralick features estimate image properties related to second-order statistics based on the grey level co-occurrence matrix (GLCM), which has been extensively used for various image processing applications. The curvelet transform has a more sparse representation of the image than wavelet, thus offering a description with higher time frequency resolution and high degree of directionality and anisotropy, which is particularly appropriate for many images rich with edges and curves. A combined feature description from Haralick feature and curvelet transform can further increase the accuracy of classification by taking their complementary information. We then investigate the applicability of the random subspace (RS) ensemble method for phenotype classification based on microscopy images. A base classifier is trained with a RS sampled subset of the original feature set and the ensemble assigns a class label by majority voting.

  • 16727.
    Zhang, Bruce
    et al.
    Texas A&M Univ, Dept Elect Engn, College Stn, TX 77843 USA..
    Kish, Laszlo Bela
    Texas A&M Univ, Dept Elect Engn, College Stn, TX 77843 USA..
    Granqvist, Claes Göran
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Drawing from hats by noise-based logic2017In: International Journal of Parallel, Emergent and Distributed Systems, ISSN 1744-5760, E-ISSN 1744-5779, Vol. 32, no 3, 244-251 p.Article in journal (Refereed)
    Abstract [en]

    We utilize the asymmetric random telegraph wave-based instantaneous noise-base logic scheme to represent the problem of drawing numbers from a hat, and we consider two identical hats with the first 2(N) integer numbers. In the first problem, Alice secretly draws an arbitrary number from one of the hats, and Bob must find out which hat is missing a number. In the second problem, Alice removes a known number from one of the hats and another known number from the other hat, and Bob must identify these hats. We show that, when the preparation of the hats with the numbers is accounted for, the noise-based logic scheme always provides an exponential speed-up and/ or it requires exponentially smaller computational complexity than deterministic alternatives. Both the stochasticity and the ability to superpose numbers are essential components of the exponential improvement.

  • 16728.
    Zhang, Changyong
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Mathematics.
    An Origin-Based Model for Unique Shortest Path Routing2014Article in journal (Refereed)
  • 16729. Zhang, Changyong
    et al.
    Rodosek, Robert
    Modelling and Constraint Hardness Characterisation of the Unique-Path OSPF Weight Setting Problem2005Conference paper (Refereed)
  • 16730. Zhang, Changyong
    et al.
    Rodosek, Robert
    Two Mathematically Equivalent Models of the Unique-Path OSPF Weight Setting Problem2005Conference paper (Refereed)
  • 16731.
    Zhang, Chao
    et al.
    CSIRO Mathematics, Informatics and Statistics, North Ryde, NSW 1670, Australia /UNSW@ADFA, Canberra, ACT 2600, Australia.
    Sun, Changming
    CSIRO Mathematics, Informatics and Statistics, North Ryde, NSW 1670, Australia.
    Pham, Tuan D
    School of Engineering and Information Technology, UNSW@ADFA, Canberra, ACT 2600, Australia.
    Vallotton, Pascal
    CSIRO Mathematics, Informatics and Statistics, North Ryde, NSW 1670, Australia.
    Fenech, Michael
    CSIRO Food and Nutritional Sciences, Adelaide, SA 5000, Australia.
    Detection of nuclear buds based on ellipse fitting2010Conference paper (Refereed)
    Abstract [en]

    Assays of micronucleus are extensively used in genotoxicity testing and in monitoring of human exposure to genotoxic materials. As nuclear buds could be a new source of micronuclei formed in interphase, the assay of contents of nuclear bud in normal and comparison group is needed. In this paper, we proposed a new automatic nuclear buds detection algorithm based on ellipse fitting. Experimental results show that our algorithm is effective and efficient. We believe that this is the first report on automated nuclear bud detection for DNA damage scoring.

  • 16732.
    Zhang, Cheng
    KTH, School of Computer Science and Communication (CSC).
    Object Detection in Natural Images.2011Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    This thesis work is aiming for detecting and localizing different classes of objects in natural images. Algorithm which start from object detection with Implicit Shape model (ISM), then with patch based class segmentation verifies hypothesis with MDL principle are used. This algorithm is able to achieve a high detection rate on both rigid and articulated objects. The thesis also proposes a novel multi-class ISM based on training joint codebook which benefits from sharing features. Experiments have verified that multi-class ISM can reach the same level of detection accuracy as the original ISM while being considerably more efficient. To further improve the computation efficiency, Information Gain(IG) integrated with word frequency criteria has been combined to select codebook entries. Evaluation shows that decreasing 60% of the codebook size would only lead to less than 5% loss in detection accuracy. To further improve the performance, saliency detection can be applied on test images on certain datasets. This has also been shown by the experiments.

  • 16733.
    Zhang, Chi
    Halmstad University, School of Information Science, Computer and Electrical Engineering (IDE).
    Tic-tac-toe game design based on Xilinx FPGA2010Independent thesis Basic level (degree of Bachelor), 15 credits / 22,5 HE creditsStudent thesis
    Abstract [en]

    This design accomplished Tic-Tac-Toe game on Xilinx Spartan-IIE FPGA platformin VHDL. Firstly, designing the circuits and wiring on experiment board. Secondly,designing the algorithm and programming it in Active-HDL. Thirdly, synthesizingit in Synplicity Synplify Pro and then implementing it in Xilinx ISE developingsuite. Finally download it onto FPGA to run it.

    This design allows two players to play Tic-Tac-Toe game on the experiment board.Pressing the key, the corresponding LED will be light up to represent thechessman. There are two LEDs indicate whose turn next is. If the grid one wantsto place chessman has been taken up, then LCD will alarm it and ask the playerto replace it. The first player who forms 3 chessmen in a row, column or diagonalwins, LCD will display it and the three LEDs in the winning line will blink. If nobody wins after filling the whole chessboard, then LCD displays draw.

  • 16734.
    Zhang, Ge
    Karlstad University, Faculty of Economic Sciences, Communication and IT, Department of Computer Science.
    An analysis for anonymity and unlinkability for a VoIP conversation2009In: PRIVACY AND IDENTITY MANAGEMENT FOR LIFE, 2009, 198-212 p.Conference paper (Refereed)
    Abstract [en]

    With the growth of its popularity, more and more VoIP services are deployed in the Internet nowadays. Similarly to other Internet applications, VoIP users may desire to be unlinkable with their participated VoIP session records for privacy issues. In this paper, we explore the Items of Interests (IOIs) from anonymization aspects based on a simplified VoIP model and analyze the potential links between them. We address possible methods to break the links. Finally, we also discuss requirements for a VoIP Anonymization Service (VAS)

  • 16735.
    Zhang, Ge
    Blekinge Institute of Technology, School of Engineering, Department of Interaction and System Design.
    Denial of Service on SIP VoIP infrastructures using DNS flooding2007Independent thesis Advanced level (degree of Master (One Year))Student thesis
    Abstract [en]

    A simple yet effective Denial of Service (DoS) attack on SIP servers is to flood the server with requests addressed at irresolvable domain names. In this paper we evaluate different possibilities to mitigate these effects and show that over-provisioning is not sufficient to handle such attacks. As a more effective approach we present a solution called the DNS Attack Detection and Prevention (DADP) scheme based on the usage of a non-blocking DNS cache. Based on various measurements conducted over the Internet we investigate the efficiency of the DADP scheme and compare its performance with different caching strategies applied.

  • 16736.
    Zhang, Ge
    Karlstad University, Faculty of Economic Sciences, Communication and IT, Department of Computer Science.
    Towards Secure SIP Signalling Service for VoIP applications: Performance-related Attacks and Preventions2009Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    Current Voice over IP (VoIP) services are regarded less secure than the traditional public switched telephone network (PSTN). This is due to the fact that VoIP services are frequently deployed in an relatively open environment so that VoIP infrastructures can be easily accessed by potential attackers. Furthermore, current VoIP services heavily rely on other public Internet infrastructures shared with other applications. Thus, the vulnerabilities of these Internet infrastructures can affect VoIP applications as well. Nevertheless, deployed in a closed environment with independent protocols, PSTN has never faced similar risks.

    The main goal of this licentiate thesis is the discussion of security issues of the Session Initiation Protocol (SIP), which serves as a signalling protocol for VoIP services. This work especially concentrates on the security risks of SIP related to performance. These risks can be exploited by attackers in two ways: either actively or passively. The throughput of a SIP proxy can be actively manipulated by attackers to reduce the availability of services. It is defined as Denial of Service (DoS) attacks. On the other hand, attackers can also profile confidential information of services (e.g., calling history) by passively observing the performance of a SIP proxy. It is defined as a timing attack. In this thesis, we carefully studied four concrete vulnerabilities existing in current SIP services, among which, three of them can lead to DoS attacks and one can be exploited for timing attacks. The results of our experiments demonstrate that these attacks can be launched easily in the real applications.

    Moreover, this thesis discusses different countermeasure solutions for the attacks respectively. The defending solutions have all in common that they are influencing the performance, by either enhancing the performance of the victim during a DoS attack, or abating the performance to obscure the time characteristic for a timing attack. Finally, we carefully evaluated these solutions with theoretical analyses and concrete experiments.

  • 16737.
    Zhang, Ge
    et al.
    Karlstad University, Faculty of Economic Sciences, Communication and IT, Department of Computer Science.
    Berthold, Stefan
    Karlstad University, Faculty of Economic Sciences, Communication and IT, Department of Computer Science.
    Hidden VoIP Calling Records from Networking Intermediaries2010Conference paper (Refereed)
    Abstract

    While confidentiality of telephone conversation contents has recently received considerable attention in Internet telephony (VoIP), the protection of the caller--callee relation is largely unexplored. From the privacy research community we learn that this relation can be protected by Chaum's mixes. In early proposals of mix networks, however, it was reasonable to assume that high latency is acceptable. While the general idea has been deployed for low latency networks as well, important security measures had to be dropped for achieving performance. The result is protection against a considerably weaker adversary model in exchange for usability. In this paper, we show that it is unjustified to conclude that low latency network applications imply weak protection. On the contrary, we argue that current Internet telephony protocols provide a range of promising preconditions for adopting anonymity services with security properties similar to those of high latency anonymity networks. We expect that implementing anonymity services becomes a major challenge as customer privacy becomes one of the most important secondary goals in any (commercial) Internet application.

  • 16738.
    Zhang, Ge
    et al.
    Karlstad University, Faculty of Economic Sciences, Communication and IT, Department of Computer Science.
    Cheng, Feng
    Meinel, Christoph
    SIMPA: A SIP-based Mobile Payment Architecture2008Conference paper (Refereed)
    Abstract [en]

    In recent years, many mobile payment (MP) schemes have been proposed and used in practise. However, a prerequisite for extended acceptance and adoption of MP technologies is to deploy an effective MP system. So far, there is no such a standardised and scalable MP platform. Most current MP schemes are circumscribed by its mobile network infrastructures. Fortunately, the fast advancement of 3G technology equips next generation mobile phone network more benefits. Following this direction, we propose SIMPA - A SIP-based Mobile Payment Architecture for next generation mobile network, which not only supports P2P payment communications between customers and merchants using Session Initiation Protocol (SIP), but also supports several traditional Internet security protocols, to enhance privacy, confidentiality and integrity during the transaction. This paper depicts detailed protocol and system architecture of SIMPA. Some application examples from customers' view are shown to demonstrate its function and feature

  • 16739.
    Zhang, Ge
    et al.
    Karlstad University, Faculty of Economic Sciences, Communication and IT, Department of Computer Science.
    Cheng, Feng
    Meinel, Christoph
    Towards Secure Mobile Payment Based on SIP2008Conference paper (Refereed)
    Abstract [en]

    Mobile payment has some unique advantages over more traditional payment methods in, for example, TV shopping and mobile multimedia services. Unfortunately, most existing mobile payment solutions rely heavily on underlying communication infrastructures, which are platform-dependent and have no unified implementation criteria. This limitation is reducing, however, through the rapid spread of the Voice over IP (VoIP) telephony service and its integration with mobile phones. The Session Initiation Protocol (SIP) is currently the standard signalling protocol of VoIP. Mobile payment is expected to be implemented and deployed in an SIP environment in order to keep pace with the evolution of the mobile phone network. The goal of this paper is firstly to propose a new mobile payment scheme based on SIP. The protocol of the proposed framework is thoroughly analysed. Secondly, we evaluate security issues and propose enhanced solutions to make this new framework applicable in practise

  • 16740.
    Zhang, Ge
    et al.
    Karlstad University, Faculty of Economic Sciences, Communication and IT, Department of Computer Science.
    Fischer Hübner, 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.
    Peer-to-Peer VoIP Communications Using Anonymisation Overlay Networks2010In: Communications and Multimedia Security: Proceedings of the 11th IFIP TC 6/TC 11, CMS2010, international conference on Communications and Multimedia Security / [ed] De Decker, Bart; Schaumüller-Bichl, Ingrid, Berlin: Springer , 2010, 130-141 p.Conference paper (Refereed)
    Abstract [en]

    Nowadays, Voice over Internet Protocol (VoIP) which enables voice conversation remotely over packet switched networks gains much attentions for its low costs and flexible services. However, VoIP calling anonymity, particularly to withhold who called whom, is difficult to achieve since VoIP infrastructures are usually deployed in an open networking environment (e.g., the Internet). Our work studies an anonymisation overlay network (AON) based solution to prevent surveillance from external attackers, who are able to wiretap the communication channels as well as to manipulate voice packets in the channels. However, it has been demonstrated that the VoIP combined with traditional AONs are vulnerable to two attacks, namely watermark attack and complementary matching attack. Taking these two attacks into account, we investigate the defensive dropping method in VoIP: A VoIP user-agent sends packets to an AON in a constant rate, but packets during periods of silence are marked. Then, the AON drops some silence packets and forwards the remaining ones to their destinations. The result of our experiments shows that the dropping rate must be carefully selected to counteract both of the two attacks. Finally, we discuss further threats in terms of this solution

  • 16741.
    Zhang, Ge
    et al.
    Karlstad University, Faculty of Economic Sciences, Communication and IT, Department of Computer Science.
    Fischer Hübner, 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.
    Bezzi, Michele
    Duquenoy, Penny
    Hansen,, Marit
    Privacy and Identity Management for Life: 5th IFIP primelife international summer school revised selected papers2010Conference paper (Refereed)
  • 16742.
    Zhang, Ge
    et al.
    Karlstad University, Faculty of Economic Sciences, Communication and IT, Department of Computer Science.
    Fischer Hübner, 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.
    Pallares, Jordi Jaen
    Rebahi, Yacine
    SIP Proxies: New Reflectors? Attacks and Defenses2010Conference paper (Refereed)
    Abstract

    To mitigate identity theft in SIP networks, an inter-domain authentication mechanism based on certificates is proposed in RFC 4474 [10]. Unfortunately, the design of the certificate distribution in this mechanism yields some vulnerabilities. In this paper, we investigate an attack which exploits SIP infrastructures as reflectors to bring down a web server. Our experiments demonstrate that the attacks can be easily mounted. Finally, we discuss some potential methods to prevent this vulnerability

  • 16743.
    Zhang, Ge
    et al.
    Karlstad University, Faculty of Economic Sciences, Communication and IT, Department of Computer Science.
    Fischer-Hübner, Simone
    Karlstad University, Faculty of Economic Sciences, Communication and IT, Department of Computer Science.
    Ehlert, Sven
    Blocking attacks on SIP VoIP proxies caused by external processing2010In: Telecommunications Systems, ISSN 1018-4864, E-ISSN 1572-9451, Vol. 45, no 1, 61-76 p.Article in journal (Refereed)
  • 16744.
    Zhang, Ge
    et al.
    Karlstad University, Faculty of Economic Sciences, Communication and IT, Department of Computer Science.
    Pallares, Jordi Jaen
    Rebahi, Yacine
    Fischer-Hübner, Simone
    Karlstad University, Division for Information Technology.
    SIP Proxies: New Reflectors in the Internet2010In: Communications and Multimedia Security: 11th IFIP TC 6/TC 11 International Conference, CMS 2010, Linz, Austria, May 31 – June 2, 2010. Proceedings, Springer, 2010, 142-153 p.Conference paper (Refereed)
    Abstract [en]

    To mitigate identity theft in SIP networks, an inter-domain authentication mechanism based on certificates is proposed in RFC 4474 [10]. Unfortunately, the design of the certificate distribution in this mechanism yields some vulnerabilities. In this paper, we investigate an attack which exploits SIP infrastructures as reflectors to bring down a web server. Our experiments demonstrate that the attacks can be easily mounted. Finally, we discuss some potential methods to prevent this vulnerability.

  • 16745.
    Zhang, Ge
    et al.
    Karlstad University, Faculty of Economic Sciences, Communication and IT, Department of Computer Science.
    Rebahi, Yacine
    Tuan Minh, Nguyen
    Performance Analysis of Identity Management in the Session Initiation protocol (SIP)2009In: Communications of the ACS, ISSN 2090-102X, Vol. 2, no 001Article in journal (Refereed)
    Abstract [en]

    The Session Initiation Protocol (SIP) is a standard for managing IP multimedia sessions in the Internet. Identity management in SIP is a crucial security field that deals with identifying users in SIP networks and controlling their access to the corresponding resources. RFC 4474 describes a mechanism, based on certificates, for dealing with the SIP users identities. This RFC recommends the use of the RSA algorithm as it is currently the most popular public key cryptography system. The proliferation of small and simple devices as well as the need to increase the capacity of the SIP servers to handle the increasing VoIP traffic will make continued reliance on RSA more challenging over time. In this paper, we describe our implementation of the current RFC 4474, our integration of elliptic curves cryptography into this RFC and show that the corresponding performance is much more significant than the one where RSA is used. This paper can be considered as a first step in standardizing the use of elliptic curves in the identity management for SIP

  • 16746.
    Zhang, Hengchong
    KTH, School of Computer Science and Communication (CSC).
    Microblog Marketing in China.2011Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Currently, microblog marketing has become an important tool for market competition among companies in many countries. People become aware of its unique commercial value and pay more attention on it. As a newly developed social media tool, although microblogging has just started in China, by the end of March in 2011, the number of registered users has drastically reached 230 million compared to 53 million one year ago and it is still increasing. As microblog becomes increasingly popular in China, it is a great platform for companies to promote their products and services, broaden their business network and build their brand. Microblogging has opened a new dimension of marketing and there is great significance for conducting research on the microblog marketing in China.

    The aim of this thesis work is to probe the strategies of microblog marketing for different companies in China which could be a guideline for those who plan to try microblog marketing.

    In order to achieve this goal and find out the useful strategies, case studies and SWOT analysis are used to analyze different situations. Specifically, three case studies are from Dell, Kogi BBQ, and VANCL, who have achieved great success via microblog marketing. Through case studies and SWOT analysis, related strategies are proposed and the trend is also predicted.

    In the end, we conclude that most companies may benefit from microblog marketing if they use it properly and take suitable strategies. However, microblog is a double-edged sword and improper message posts may bring negative effects to companies. Companies should treat microblog cautiously and make good use of it.

    Key words: Microblog, Microblog marketing, Strategy, Company

  • 16747.
    Zhang, Hong
    et al.
    Umeå University, Faculty of Science and Technology, Department of Mathematics and Mathematical Statistics. Jiangsu Univ, Dept Math, Zhenjiang 212013, Jiangsu, Peoples R China.
    Georgescu, Paul
    The global properties of an age-dependent SI model involving pathogenic virus release and defence mechanisms for pests2010In: Mathematical and computer modelling, ISSN 0895-7177, Vol. 52, no 1-2, 37-54 p.Article in journal (Refereed)
    Abstract [en]

    Insect pests are common but undesirable elements in ecosystems and represent thorny problems for most developing countries. To prevent pest outbreaks, growers often resort to insect-pathogenic viruses rather than to pesticides which affect human health and the environment. The purpose of this paper is to investigate a new age-structured pest management model which describes the interaction between susceptible insect pests, infected insect pests, pathogenic viruses and defence immunity mechanisms. A feature of this model is that it accounts for the dependence of the amount of pathogenic viruses released and of the efficiency of the defence mechanisms upon the so-called age of infection. First, the asymptotic behavior of the system is established via a monotonicity argument which makes use of several integral inequalities, being shown that the infection ultimately dies out, while under certain circumstances the susceptible pests also become extinct. By means of the Michailov criterion, one then analyzes the linearized stability of the trivial equilibrium and of the semi-trivial infected pest-free equilibrium. In this regard, it is observed that the defence mechanisms and maximal length of the infective period play important roles in the dynamics of the system. Several pest controls strategies are further investigated by means of numerical simulations, which show that when the dose of pathogenic viruses released initially is larger than a certain amount the profile of the response of defence mechanisms can be modified by changing this dose. Finally, the paper is concluded with a discussion on the biological significance of the mathematical results and framework.

  • 16748.
    Zhang, Kerry
    KTH, School of Computer Science and Communication (CSC).
    Viewpoint and Topic Modeling of Current Events2016Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    There are multiple sides to every story, and while statistical topic models have been highly successful at topically summarizing the stories in corpora of text documents, they do not explicitly address the issue of learning the different sides, the viewpoints, expressed in the documents. In this paper, we show how these viewpoints can be learned completely unsupervised and represented in a human interpretable form. We use a novel approach of applying CorrLDA2 for this purpose, which learns topic-viewpoint relations that can be used to form groups of topics, where each group represents a viewpoint. A corpus of documents about the Israeli-Palestinian conflict is then used to demonstrate how a Palestinian and an Israeli viewpoint can be learned. By leveraging the magnitudes and signs of the feature weights of a linear SVM, we introduce a principled method to evaluate associations between topics and viewpoints. With this, we demonstrate, both quantitatively and qualitatively, that the learned topic groups are contextually coherent, and form consistently correct topic-viewpoint associations.

  • 16749.
    Zhang, Linfan
    et al.
    Kristianstad University, School of Health and Society.
    Zheng, Shuang
    Kristianstad University, School of Health and Society.
    Enhancing QR Code Security2015Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Quick Response code opens possibility to convey data in a unique way yet insufficient prevention and protection might lead into QR code being exploited on behalf of attackers. This thesis starts by presenting a general introduction of background and stating two problems regarding QR code security, which followed by a comprehensive research on both QR code itself and related issues. From the research a solution taking advantages of cloud and cryptography together with an implementation come after. We also give an objective evaluation on the outcome in comparison to existing QR products. They are based on the purpose of enhancing QR code security and aim to interpret how we have tackle the specified problems meanwhile to suggest possible further work for bringing security of QR code to a higher level. 

  • 16750.
    Zhang, Liwei
    et al.
    University of Hamburg, Germany.
    Saffiotti, Alessandro
    Örebro University, School of Science and Technology.
    Pecora, Federico
    Örebro University, School of Science and Technology.
    Zhang, Jianwei
    University of Hamburg, Germany.
    Evaluation metrics for an experience-based mobile artificial cognitive system2014In: 11th World Congress on Intelligent Control and Automation (WCICA2014), Springer Berlin/Heidelberg, 2014, 2225-2232 p.Conference paper (Refereed)
    Abstract [en]

    In this paper, an FIM (Fitness to Ideal Model)and a DLen (Description Length) based evaluation approachhas been developed to measure the benefit of learning from experienceto improve the robustness of the robot’s behavior. Theexperience based mobile artificial cognitive system architectureis briefly described and adopted by a PR2 service robot withinthe EU-FP7 funded project RACE. The robot conducts typicaltasks of a waiter. Temporal and lasting obstacles and standardtable items, as shown in the demonstrations of “Deal-withobstacles”and “Clear-table-intelligently”, are being adoptedin this work to test the proposed evaluation metrics, validateit on a real PR2 robot system and present the evaluationresults. The relationship between the FIM and DLen has beenvalidated. This work proposes an effective approach to evaluatea cognitive service robot system which enhances its performanceby learning.

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