Computer Engineering / Bilgisayar Mühendisliği

Permanent URI for this collectionhttps://hdl.handle.net/11147/10

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2005 - 200912010 - 20173

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Institution Author: search.filters.institutionAuthor.Ayav, TolgaPublisher: search.filters.publisher.Springer Verlag

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Now showing 1 - 4 of 4
  • Article
    Citation - WoS: 26
    Citation - Scopus: 30
    Ensuring Performance and Provider Profit Through Data Replication in Cloud Systems
    (Springer Verlag, 2017) Tos, Uras; Mokadem, Riad; Hameurlain, Abdelkader; Ayav, Tolga; Bora, Şebnem
    Cloud computing is a relatively recent computing paradigm that is often the answer for dealing with large amounts of data. Tenants expect the cloud providers to keep supplying an agreed upon quality of service, while cloud providers aim to increase profits as it is a key ingredient of any economic enterprise. In this paper, we propose a data replication strategy for cloud systems that satisfies the response time objective for executing queries while simultaneously enables the provider to return a profit from each execution. The proposed strategy estimates the response time of the queries and performs data replication in a way that the execution of any particular query is still estimated to be profitable for the provider. We show with simulations that how the proposed strategy fulfills these two criteria.
  • Conference Object
    Model Checker-Based Delay Fault Testing of Sequential Circuits
    (Springer Verlag, 2015) Takan, Savaş; Güler, Berkin; Ayav, Tolga
    This paper applies model checker-based testing, a well-known method from software engineering, to the delay fault testing of synchronous sequential logic circuits. We first model the circuit as timed automata to reveal its timing characteristics. The model is repeatedly mutated by injecting the delay faults under a certain fault assumption and all the mutant models are checked against the given properties by exploiting a model checker. Counterexamples returned from the model checker form the basis of test input sequences. Finally, the test suite minimization is defined as an integer programming problem.
  • Article
    Citation - WoS: 24
    Citation - Scopus: 31
    Dynamic Replication Strategies in Data Grid Systems: A Survey
    (Springer Verlag, 2015) Tos, Uras; Mokadem, Riad; Hameurlain, Abdelkader; Ayav, Tolga; Bora, Şebnem
    In data grid systems, data replication aims to increase availability, fault tolerance, load balancing and scalability while reducing bandwidth consumption, and job execution time. Several classification schemes for data replication were proposed in the literature, (i) static vs. dynamic, (ii) centralized vs. decentralized, (iii) push vs. pull, and (iv) objective function based. Dynamic data replication is a form of data replication that is performed with respect to the changing conditions of the grid environment. In this paper, we present a survey of recent dynamic data replication strategies. We study and classify these strategies by taking the target data grid architecture as the sole classifier. We discuss the key points of the studied strategies and provide feature comparison of them according to important metrics. Furthermore, the impact of data grid architecture on dynamic replication performance is investigated in a simulation study. Finally, some important issues and open research problems in the area are pointed out.
  • Article
    Optimal Control for Real-Time Feedback Rate-Monotonic Schedulers
    (Springer Verlag, 2005) Ayav, Tolga; Ferrari-Trecate, Giancarlo
    This paper presents an optimal control scheme for a real-time feedback control rate-monotonic scheduling (FC-RMS) system. We consider two-version tasks composed of a mandatory and an optional part to be scheduled according to the FC-RMS. In FC-RMS, the controller provides a feedback strategy for deciding about the execution or rejection of the optional sub-tasks. By modeling the task execution times as random variables, we first find the statistical model of FC-RMS and then we design a pure optimal controller and an optimal controller with feedforward integral compensation. The comparison of these two schemes with common Proportional-Integral-Derivative (PID) controller highlights the benefit of the optimal scheme with integral compensation. The results are demonstrated through the real implementation of FC-RMS on RT-Linux.