Computer Engineering / Bilgisayar Mühendisliği

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

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End date: 2009Publisher: search.filters.publisher.Institute of Electrical and Electronics Engineers Inc.

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Now showing 1 - 10 of 21
  • Conference Object
    Citation - Scopus: 2
    Telsiz Duyarga Ağlarında Hızlı Hareket Eden Hedefler için Küme Tabanlı Hedef İzleme Algoritması
    (Institute of Electrical and Electronics Engineers Inc., 2009) Alaybeyoğlu, Ayşegül; Dağdeviren, Orhan; Kantarcı, Aylin; Erciyes, Kayhan
    Kablosuz iletişim teknolojilerindeki ilerlemelerle birlikte telsiz duyarga ağları (TDA) birçok sivil ve askeri uygulamalarda özellikle de hareketli hedefin takibi gibi konularda yaygın olarak kullanılmaya başlanmıştır. Bu çalışmada da TDA’da hızlı hareket eden nesneler için küme tabanlı bir hedef izleme algoritması önerilmiştir. Literatürde bulunan mevcut çalışmalarda lider düğüm, hedefin sadece t+1 anında yaklaşacağı konumu tahminleyerek bu konuma en yakın düğümü uyandırır. Hedefin çok hızlı hareket etmesi durumunda ise hedefin kısa süre içerisinde bir grup düğümün yakınlarından algılanmadan geçip gitmesi söz konusudur. Önermiş olduğumuz algoritma ile hedefin hızına bağlı olarak, hedefin tahmini gideceği yöndeki düğümler önceden uyandırılarak, kümeler önceden oluşturulmaktadır. Böylece hedefin ani hızlanması durumunda, önceden oluşturmuş olduğumuz kümeler sayesinde hedefin kaybolma riskini azaltmış bulunmaktayız.
  • Conference Object
    Citation - WoS: 1
    Feedback Control Static Scheduling for Real-Time Distributed Embedded Systems
    (Institute of Electrical and Electronics Engineers Inc., 2005) Ayav, Tolga; Sorel, Yves
    This paper presents an implementation of feedback control strategy on distributed static scheduling. The static schedule is created taking into account the average execution times of the tasks. Feedback control algorithm handles the unestimated dynamic behaviors in the system and keeps the performance at a desired level. The approach of feedback control supporting static scheduling yields more flexible scheduling, low scheduling overhead and better resource utilization while preserving the realtime constraints.
  • Conference Object
    Citation - WoS: 26
    Citation - Scopus: 40
    Solving the Course Scheduling Problem Using Simulated Annealing
    (Institute of Electrical and Electronics Engineers Inc., 2009) Aycan, Esra; Ayav, Tolga
    This paper tackles the NP-eomplete problem of academic class scheduling (or timetabling). The aim is to find a feasible timetable for the department of computer engineering in Izmir Institute of Technology. The approach focuses on simulated annealing. We compare the performance of various neighborhood searching algorithms based on so-called simple search, swapping, simple search-swapping and their combinations, taking into account the execution times and the final costs. The most satisfactory timetable is achieved with the combination of all these three algorithms. The results highlight the efficacy of the proposed scheme
  • Conference Object
    Citation - Scopus: 4
    An Architecture for Verification of Access Control Policies With Multi Agent System Ontologies
    (Institute of Electrical and Electronics Engineers Inc., 2009) Tekbacak, Fatih; Tuğlular, Tuğkan; Dikenelli, Oğuz
    Multi-agent systems (MAS) which communicate with intra-domain and inter-domain agent platforms have access control requirements. Instead of a central mechanism, a fine-graned access control mechanism could have been applied to MAS platforms. This paper emphasizes MAS-based domain and security ontologies with XACML-based access control approach for MAS platforms. The domain dependent behaviour and access control parameters in agent ontologies could be combined within a common XACML policy document that is used through different MAS applications. Agent-based access control requirements and common XACML policy documents should be consistent to enforce policies for MAS. To obtain this condition, the translation of organizational policies and platform based policies have to be considered in detail and the verified policy features have to be enforced in MAS to provide access for resources.
  • Conference Object
    Citation - Scopus: 5
    Gui-Based Testing of Boundary Overflow Vulnerability
    (Institute of Electrical and Electronics Engineers Inc., 2009) Tuğlular, Tuğkan; Müftüoğlu, Can Arda; Kaya, Özgür; Belli, Fevzi; Linschulte, M.
    Boundary overflows are caused by violation of constraints, mostly limiting the range of internal values of a program, and can be provoked by an intruder to gain control of or access to stored data. In order to countermeasure this well-known vulnerability issue, this paper focuses on input validation of graphical user interfaces (GUI). The approach proposed generates test cases for numerical inputs based on GUI specification through decision tables. If boundary overflow error(s) are detected, the source code will be analyzed to localize and correct the encountered error(s) automatically.
  • Conference Object
    Citation - WoS: 5
    Citation - Scopus: 6
    The 1st Workshop on Model-Based Verification & Validation: Directed Acyclic Graph Modeling of Security Policies for Firewall Testing
    (Institute of Electrical and Electronics Engineers Inc., 2009) Tuğlular, Tuğkan; Kaya, Özgür; Müftüoğlu, Can Arda; Belli, Fevzi
    Currently network security of institutions highly depend on firewalls, which are used to separate untrusted network from trusted one by enforcing security policies. Security policies used in firewalls are ordered set of rules where each rule is represented as a predicate and an action. This paper proposes modeling of firewall rules via directed acyclic graphs (DAG), from which test cases can be automatically generated for firewall testing. The approach proposed follows test case generation algorithm developed for event sequence graphs. Under a local area network setup with the aid of a specifically developed software for this purpose, generated test cases are converted to network test packets, test packets are sent to the firewall under test (FUT), and sent packets are compared with passed packets to determine test result.
  • Conference Object
    Citation - Scopus: 3
    Protocol-Based Testing of Firewalls
    (Institute of Electrical and Electronics Engineers Inc., 2009) Tuğlular, Tuğkan; Belli, Fevzi
    A firewall is the most important tool of network security defense. Its proper functioning is critical to the network it protects. Therefore a firewall should be tested rigorously with respect to its implemented network protocols and security policy specification. We propose a combined approach for test case generation to uncover errors both in firewall software and in its configuration. In the proposed approach, abstract test cases are generated by mutating event sequence graph model of chosen network protocol and filled with values from policy specification by using equivalence partitioning and boundary value analysis. A case study is presented to validate the presented approach.
  • Conference Object
    Citation - Scopus: 3
    Grid Resource Discovery Based on Web Services
    (Institute of Electrical and Electronics Engineers Inc., 2009) Çokuslu, Deniz; Hameurlain, Abdelkader; Erciyeş, Kayhan
    The size of grid systems has increased substantially in the last decades. Resource discovery in grid systems is a fundamental task which provides searching and locating necessary resources for a given process. Various different approaches are proposed in literature for this problem. Grid resource discovery using web services is an important approach which has resulted in many tools to become de facto standards of today's grid resource management. In this paper, we propose a survey of recent grid resource discovery studies based on web services. We provide synthesis, analysis and evaluation of these studies by classification. We also give a comparative study of different classes proposed.
  • Conference Object
    Citation - Scopus: 9
    Event-Based Input Validation Using Design-By Patterns
    (Institute of Electrical and Electronics Engineers Inc., 2009) Tuğlular, Tuğkan; Müftüoğlu, Can Arda; Belli, Fevzi; Linschulte, M.
    This paper proposes an approach for validation of numerical inputs based on graphical user interfaces (GUI) that are modeled and specified by event sequence graphs (ESG). For considering complex structures of input data, ESGs are augmented by decision tables and patterns of design by contract (DbC). The approach is evaluated by experiments on boundary overflows, which occur when input values violate the range of specified values. Furthermore, a tool is presented that implements our approach enabling a semiautomatically detection of boundary overflow errors and suggesting correction steps based on DbC.
  • Conference Object
    Citation - WoS: 13
    Citation - Scopus: 14
    Performance Evaluation of Cluster-Based Target Tracking Protocols for Wireless Sensor Networks
    (Institute of Electrical and Electronics Engineers Inc., 2009) Alaybeyoğlu, Ayşegül; Dağdeviren, Orhan; Erciyeş, Kayhan; Kantarcı, Aylin
    Target tracking is an important application type for wireless sensor networks (WSN). Recently, various approaches [1-11] are proposed to maintain the accurate tracking of the targets as well as low energy consumption. Clustering is a fundamental technique to manage the scarce network resources [12-19]. The message complexity of an application can be significantly decreased when it is redesigned on top of a clustered network. Clustering has provided an efficient infrastructure in many existing studies [1-8]. The clusters can be constructed before the target enters the region which is called the static method [1-4] or clusters are created by using received signal strength (RSS) from target which is called the dynamic method [5-8]. In this paper we provide simulations of static and dynamic clustering algorithms against various mobility models and target speeds. The mobility models that we applied are Random Waypoint Model, Random Direct Model and Gauss Markov Model. We provide metrics to measure the tracking performance of both approaches. We show that the dynamic clustering is favorable in terms of tracking accuracy whereas the energy consumption of static clustering is significantly smaller. We also show that the target moving with Gauss Markov Model can be tracked more accurately than the other models.