Papers by Ahmet Sekercioglu
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Ad Hoc Networks, 2013
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2008 International Symposium on a World of Wireless, Mobile and Multimedia Networks, 2008
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AIAA SPACE 2013 Conference and Exposition, 2013
ABSTRACT The advanced, long range, hypersonic SpaceLiner concept aims to revolutionize the passen... more ABSTRACT The advanced, long range, hypersonic SpaceLiner concept aims to revolutionize the passenger transportation market through marrying high speed intercontinental travel with the adventure, prestige and allure of private commercial space flight. Designed to carry 50 passengers from Australia to Europe in suborbital flight, the concept itself was proposed in 2005 by the DLR. Since then, it been extensively investigated, most recently within the framework of the EU funded, international FAST20XX and CHATT collaborative projects. However, before SpaceLiner can become a reality, considerable efforts and extensive research are still needed in order to advance the concept through to a mature stage. Throughout the course of existing studies, numerous challenges and considerations spanning various disciplines and areas, including technology, structure, thermo- and aerodynamics, safety, reusability and logistics, have been encountered and explicitly identified. Another critical consideration within the scope of the early phase studies, is the question of expected program cost. In particular, the non-recurring yet prevalent development costs are of interest, with the logical question arising of whether they will be borne by private investors, industry, government institutions, or a combination of the latter. This paper therefore briefly yet categorically outlines the key existing challenges and considerations within the scope and context of the current SpaceLiner design phase. The topics of cost estimation and cost modeling for SpaceLiner are expanded upon in detail and constitute the focus of this paper. Appropriate methods, models and tools to potentially implement during early program cost estimate formulation are also proposed, and their selection justified. How to approach compiling a justifiable and structured cost estimate to address SpaceLiner vehicle development and production is addressed, and operation cost considerations explored. Furthermore, a method and software tool for identifying and establishing a viable business case involving private investment and funding of the SpaceLiner program, is presented and critically discussed.
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International Conference on Telecommunications, 2000
In this paper we investigate the usefulness of an evolutionary programming (EP) optimization algo... more In this paper we investigate the usefulness of an evolutionary programming (EP) optimization algorithm for tackling the problem of Bandwidth Allocation for Virtual Paths (EP-BAVP). Results for two network topologies obtained with EP are in close agreement with those obtained using a classical constrained optimization (CCO) technique. In the simplest topology (3 nodes) the EP algorithm achieves the same throughputs
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Proceedings of SPIE - The International Society for Optical Engineering
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In this paper, we study the performanceofafuzzycontrol scheme as a first step to develop betterco... more In this paper, we study the performanceofafuzzycontrol scheme as a first step to develop bettercontrol strategies for avoiding congestion and attaining high link utilisation in ATM based networks. Due to the complexity of ATM networks and many parameters involved, explicit modeling oftheir dynamic behaviour is very difficult if not impossible. On the other hand, for systems whichare difficult to obtain analytical models for, approximate models developed by using fuzzy logicbasedtechniques arebeing applied successfully.
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ITRE 2005. 3rd International Conference on Information Technology: Research and Education, 2005., 2005
In this paper, we describe our software tool (IPv6Suite) which is capable of simulating IPv6 netw... more In this paper, we describe our software tool (IPv6Suite) which is capable of simulating IPv6 networks accurately. The IPv6 network components are modeled in detail with important functionalities closely following the relevant protocol standard. The OMNeT++ simulation environment is used, providing a generic and flexible architecture with a strong graphical user interface (GUI) support. This allowed the construction of a
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We consider a high speed integrated services network, and investigate compare and contrast the pe... more We consider a high speed integrated services network, and investigate compare and contrast the performance of two algorithms for solving the Aggregated Bandwidth Allocation (BA) problem. The algorithms we focus our attention are: (1) a classical constrained optimisation (CCO) algorithm and (2) a constrained optimisation Genetic Algorithm (GA). We adopt the Virtual Path (VP) concept for ATM (Asynchronous Transfer Mode) networks as an example, but expect the findings to be equally applicable for other aggregated bandwidth allocation problems, such as in networks using MPLS (Multiprotocol Label Switching). We define a fair multiobjective criterion for maximisation of network throughput, based on a probability (density) function for bandwidth demand. We convert to single optimisation problem and study network topologies involving varying number of nodes. We compare throughput, fairness and time complexity of GA-BAVP and CCO-BAVP. The results on maximising the throughput obtained with GA...
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IAES International Journal of Robotics and Automation (IJRA), 2012
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This paper presents a new active queue management (AQM) scheme, Fuzzy Explicit Marking (FEM), sup... more This paper presents a new active queue management (AQM) scheme, Fuzzy Explicit Marking (FEM), supporting explicit congestion notification (ECN), to provide congestion control in TCP/IP best-effort networks using a fuzzy logic control approach. While many AQM mechanisms have recently been proposed, these require careful configuration of non-intuitive control parameters, and show weaknesses to detect and control congestion under dynamic traffic
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This paper presents a new active queue management (AQM) scheme -Fuzzy Explicit Marking (FEM)- sup... more This paper presents a new active queue management (AQM) scheme -Fuzzy Explicit Marking (FEM)- supporting explicit congestion notification (ECN), to provide congestion control in TCP/IP best- effort networks using a fuzzy logic control approach. While many AQM mechanisms have recently been proposed, these require careful configuration of non- intuitive control parameters, and show weaknesses to detect and control congestion under
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2013 Seventh International Conference on Distributed Smart Cameras (ICDSC), 2013
ABSTRACT This work presents a new method to efficiently communicate the correlated visual and dep... more ABSTRACT This work presents a new method to efficiently communicate the correlated visual and depth information captured by multiple mobile RGB-D camera sensors. Our proposed scheme adopting the special properties of the depth map can extract the uncorrelated information between two images without conducting computationally heavy motion estimation. Moreover, a novel entropy coding scheme is proposed to further compress the depth data.
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2013 Seventh International Conference on Distributed Smart Cameras (ICDSC), 2013
ABSTRACT In mobile visual sensor networks, relative pose (location and orientation) estimation is... more ABSTRACT In mobile visual sensor networks, relative pose (location and orientation) estimation is a prerequisite to accomplish a wide range of collaborative tasks. In this paper, we present a distributed, peer-to-peer algorithm for relative pose estimation in a network of mobile robots equipped with RGB-D cameras acting as a visual sensor network. Our algorithm uses the depth information to estimate the relative pose of a robot when camera sensors mounted on different robots observe a common scene from different angles of view. To create the algorithm, we first developed a framework based on the beam-based sensor model to eliminate the adverse effects of the situations where two views of a scene each are partially seen by the sensors. Then, in order to cancel the bias introduced by the beam-based sensor model, we developed a scheme that allows the algorithm to symmetrize across the two views. We conducted simulations and also implemented the algorithm on our mobile visual sensor network testbed. Both the simulations and experimental results indicate that the proposed algorithm is fast enough for real-time operation and able to maintain a high estimation accuracy. To our knowledge, it is the first distributed relative pose estimation algorithm that uses the depth information captured by multiple RGB-D cameras.
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2013 Seventh International Conference on Distributed Smart Cameras (ICDSC), 2013
ABSTRACT We present a survey of recent research works on multiview image compression and transmis... more ABSTRACT We present a survey of recent research works on multiview image compression and transmission techniques developed for Wireless Multimedia Sensor Networks (WMSNs). We classify them into two categories with respect to the coding methods adopted: (i) in-network processing with joint coding schemes, and (ii) distributed source coding schemes. The survey also includes a comprehensive evaluation of the limitations of each approach. Based on the review results, we discuss future research directions, and identify the ways of more efficient transmission of the spatially correlated and redundant data in WMSNs.
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Proceedings of the Eighth IEEE Symposium on Computers and Communications. ISCC 2003, 2003
Abstract This paper presents a new active queue management scheme, fuzzy explicit marking (FEM), ... more Abstract This paper presents a new active queue management scheme, fuzzy explicit marking (FEM), implemented within the differentiated services (Diffserv) framework to provide the congestion control using a fuzzy logic control approach. Network congestion control remains a critical and high priority issue. The rapid growth of the Internet and increased demand to use the Internet for time-sensitive voice and video applications necessitate the design and utilization of effective congestion control algorithms, especially ...
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Papers by Ahmet Sekercioglu