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Conference Object Citation - WoS: 4A Layered Security Architecture for Corporate 802.11 Wireless Networks(Ieee, 2004) Erten, YM; Tomur, EIn this study we have investigated the security aspects of wireless local area networks and discussed the weaknesses associated with various conventional 802.11 security protocols such as WEP and 802.1x. We propose an architecture to control access to corporate 802.11 wireless networks, based on the privileges and location of users, using the tested wired network components such as VPNs and Firewalls. The presented architecture reduces the security risks in enterprise level deployment of wireless LANs.Conference Object A Bayes decision model for RSS based location estimation(Ieee, 2007) Dincer, Zeynep; Oektem, Rwen; Aydin, ElifThis work introduces a location estimation method based on Bayes Decision Theory using Radio Signal Strengths for indoor environment. Signal Strengths are observed through three transmitters at three distinct frequencies in UHF band, an active RFID tag and a modem connected to a computer. The test environment is 2100cmx720cm, which is divided into classed of square grids. For each class, a set of received signal strengths are measured and processed. Assuming that the class in which the RFID tag was located in the previous time of measurement is known, the next location (class) is estimated using Bayes Decision Theory. Proposed method is tested in a laboratory environment with obstacles. Results show that proposed method will be successful in location estimation where the estimation error stays within around 2m.Conference Object Citation - WoS: 7Citation - Scopus: 8Formation Control of a Multi-Agent System Using Decentralized Nonlinear Servomechanism(Ieee, 2003) Gazi, VIn this article we consider the formation control problem of a system of M agents with general nonlinear dynamics. We show that the problem of the agents moving in a formation along constant or periodic trajectories can be formulated as a nonlinear output regulation (servomechanism) problem and solved using known techniques. Then, we consider the example of formation control of agents with point mass dynamics and apply the procedure. Few illustrative numerical simulation examples are also provided.Conference Object Citation - WoS: 13Citation - Scopus: 34Swarm Aggregations Using Artificial Potentials and Sliding Mode Control(Ieee, 2003) Gazi, VIn this article we build on our earlier results in [1, 2] on swarm stability. In [1, 2] we had considered aggregating swarm model in n-dimensional space based on artificial potential functions for inter-individual interactions and motion along the negative gradient of the combined potential. Here we consider a general model for vehicle dynamics of each agent (swarm member) and use sliding mode control theory to force their motion to obey the dynamics of the swarm considered in [1, 2]. In this context, the results in [1, 2] serve as a "proof of concept" for swarm aggregation, whereas the present results serve as possible implementation method for engineering swarms with given vehicle dynamics. Moreover, the presented control scheme is robust with respect to disturbances and system uncertainties.Conference Object Distance Laboratory Applications Errl(Ieee, 2008) Aydin, C. C.; Turkmen, G.; Ozyurt, E.; Aydin, E. U.; Cagiltay, N. E.; Ozbek, M. E.; Kara, A.In the last decade, the effect of internet usage in education is gradually increased. When we look from academic perspective, the new technologies provided alternatives for students learning. As distance education becomes important everyday, the indispensable elements of teaching and education, laboratories must be reachable via remote connection. Consequently, the education that is going to be given to the students will be more flexible with respect to place and time constraints and students can reach laboratory facilities at any time and anywhere not only in lectures and practical hours. In this study, European Remote Radio Laboratory (ERRL) which is a distance remote Radio Frequency (RF) laboratory designed for electrical-electronics students, is described generally. The software architecture, infrastructure and experiment that can be done with a remote connection have been described.Conference Object An Rfid Based Location Finding and Tracking With Guidance(Ieee, 2008) Oktem, Rusen; Aydin, Elif Uray; Cagiltay, Nergiz ErcilThis paper tackles an RFID based location finding and tracking system. The system is an integral part of a navigation aid being developed for guiding visually disabled people in a store. The aid is composed of a portable hardware interface unit, a standalone RFID unit, and a central processing unit. The units interact via wireless communication to locate the position of the user in a known indoor environment and tracking his/her movement. An active RFID tag helps to estimate the location of a user and the user is guided to follow a route accordingly, via a tactile compass. The system uses RF signal strengths and is based on Bayes Decision Theory. Initial simulation results with the system prove promising for location finding and tracking, especially when the tracked person is guided by a system.Conference Object An Investigation About Process Matchmaking Performances of Unstructured and Decentralized Digital Environments(Ieee, 2007) Cakir, Bugra; Kilic, HurevrenEfficient matchmaking is an important problem in unstructured and decentralized digital environments. We report the results of simulations of these environments and provide measurements of match performance focusing on unstructured and decentralized environments. In the study, different environment models including P2P (Hypergrid, Gnutella with/without ultrapeer); small-world (Watts-Strogatz); heavy-tailed and random versions of Autonomous System Waxman model showing power-law distribution property; random and 2D-Grid are considered. The flooding mechanism enabling process encounters for match purposes is uninformed Breadth-First-Search. Simulations show that the matchmaking performance of random environment outperforms the others for almost all different problems and time-to-live settings. On the other hand, the total cost of small world environment model is the highest for almost all setups.Conference Object Citation - WoS: 6Bar Code Localization in Wavelet Domain by Using Binary Morphology(Ieee, 2004) Öktem, REIn this paper, a wavelet transform based bar code localization algorithm is proposed. The algorithm is designed to enable fast and memory efficient application for automatic bar code recognition systems that are used in big manufacturing and distribution units. The region of interest areas are kept and other regions are discarded by applying binary morphology on wavelet transform coefficients.Conference Object Comparative Study of Cognitive Complexity Measures(Ieee, 2008) Misra, Sanjay; Mısra, Sanjay; Akman, Ibrahim; Akman, Kamil İbrahim; Mısra, Sanjay; Akman, Kamil İbrahim; Computer Engineering; Computer EngineeringComplexity metrics are used to predict critical information about reliability and maintainability of software systems. Cognitive complexity measure based on cognitive informatics, plays an important role in understanding the fundamental characteristics of software, therefore directly affects the understandability and maintainability of software systems. In this paper, we compared available cognitive complexity measures and evaluated cognitive weight complexity measure in terms of Weyuker's properties.Conference Object How Assessment System of an Open Source Learning Management System Can Be Integrated To a Remote Laboratory Application? Problems and Solutions(Ieee, 2007) Aydin, Cansu Cigdem; Cagiltay, Nergiz ErcilMost of the education programs need an assessment system for formative and summative evaluation purposes. Similarly, in the ERRL* project which is a distance remote radio frequency laboratory application, assessment system is required. However, developing an assessment system cost is very high and requires some extra time for testing and development purposes. Open source systems provide these services in a standard way. Since the source is open, it is possible to make some modifications to better adapt these systems to the requirements of developed systems. Similarly, in the Moodle part of the system we need to integrate the test and the experiment platforms. hi order to better guide the learners in the system, they should take some tests about the devices and the theoretical content included in the system. It is important to prevent users Who do not have the enough knowledge directed to the experiments platform. These testing requirements should be integrated into the remote laboratory system, so that, the learners should not need to jump between different systems and interfaces. This article presents implementation process of open source Learning Management System software's assessment module to a remote laboratory application and it also discusses the advantages, disadvantages of using an open source Web based assessment system.
