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Article A New Model for Indoor Propagation Prediction Using Genetic Algorithm(Ieice-inst Electronics information Communications Eng, 2008) Aydin, ElifIn this study, a new, simple and accurate computation of the received signal strength (RSS) level for indoor environment is performed. The genetic algorithm (GA) approach is used for prediction of the RSS. The proposed model is formed on the knowledge of measurements without requiring any detail of the environment. The model provides a time efficient method to estimate RSS dynamically at any location in the test environment. The accuracy of the measurement results and the genetic algorithm approach are presented for three distinct transmitters located at different positions.Article ISAR Imaging of Drone Swarms at 77 GHz(Tubitak Scientific & Technological Research Council Turkey, 2025) Coruk, Remziye Busra; Kara, Ali; Aydin, ElifThe proliferation of easily available, internet-purchased drones, coupled with the emergence of coordinated drone swarms, poses a significant security threat for airspace. Detecting these swarms is crucial to prevent potential accidents, criminal misuse, and airspace disruptions. This paper proposes a novel inverse synthetic aperture radar (ISAR) imaging technique for high-resolution reconstruction of drone swarms at 77 GHz millimeter wave (mmWave) frequency, offering a valuable tool for military and defense antidrone systems. The key parameters affecting down-range and cross-range resolution (0.05 m), ultimately enabling the generation of detailed ISAR images are discussed. Here, we create diverse scenarios encompassing various swarm formations, sizes, and payload configurations by employing ANSYS simulations. To enhance image quality, different window functions are evaluated, and the Hamming window is selected due to its highest peak signal-to-noise ratio (PSNR) (16.3645) and structural similarity (SSIM) (0.9067) values, ensuring superior noise reduction and structural preservation. The results demonstrate that the effectiveness of high-resolution ISAR imaging in accurately detecting and characterizing drone swarms pave the way for enhanced airspace security measures.Conference Object Citation - WoS: 17Citation - Scopus: 23Maintenance, Sustainability and Extendibility in Virtual and Remote Laboratories(Elsevier Science Bv, 2011) Kara, Ali; Ozbek, Mehmet Efe; Cagiltay, Nergiz Ercil; Aydin, ElifThis study presents discussions on sustainability of Virtual and Remote Laboratories (VRL), and provides challenges toward maintenance of VRLs. Technical and pedagogical issues in extension and sustenance of VRLs are discussed with the experiences of the authors gained in the development of a VRL system, European Remote Radio Laboratory (ERRL) platform. Moreover, the study presents actions to be taken in sustenance plan and expendability of VRL system with the advances in Information and Communication Technologies (ICT) and educational technologies along with the needs of educators and learners in formal education. (C) 2011 Published by Elsevier Ltd.Article Citation - WoS: 1Citation - Scopus: 1Millimeter-Wave Sar Imaging for Sub-Millimeter Defect Detection With Non-Destructive Testing(Mdpi, 2025) Yalcinkaya, Bengisu; Aydin, Elif; Kara, AliThis paper introduces a high-resolution 77-81 GHz mmWave Synthetic Aperture Radar (SAR) imaging methodology integrating low-cost hardware with modified radar signal characteristics specifically for NDT applications. The system is optimized to detect minimal defects in materials, including low-reflectivity ones. In contrast to the existing studies, by optimizing key system parameters, including frequency slope, sampling interval, and scanning aperture, high-resolution SAR images are achieved with reduced computational complexity and storage requirements. The experiments demonstrate the effectiveness of the system in detecting optically undetectable minimal surface defects down to 0.4 mm, such as bonded adhesive lines on low-reflectivity materials with 2500 measurement points and sub-millimeter features on metallic targets at a distance of 30 cm. The results show that the proposed system achieves comparable or superior image quality to existing high-cost setups while requiring fewer data points and simpler signal processing. Low-cost, low-complexity, and easy-to-build mmWave SAR imaging is constructed for high-resolution SAR imagery of targets with a focus on detecting defects in low-reflectivity materials. This approach has significant potential for practical NDT applications with a unique emphasis on scalability, cost-effectiveness, and enhanced performance on low-reflectivity materials for industries such as manufacturing, civil engineering, and 3D printing.Article Citation - WoS: 5Citation - Scopus: 6Miniaturised Antenna at a Sub-Ghz Band for Industrial Remote Controllers(inst Engineering Technology-iet, 2019) Yilmaz, Vadi Su; Bilgin, Gulsima; Aydin, Elif; Kara, AliThis study presents the design and the fabrication of a miniaturised sub-GHz antenna for remote control applications. Miniaturisation techniques were examined to identify the most appropriate topology for sub-GHz band requirements. First, the design parameters of the antenna were determined, and then, a commercial electromagnetic simulation tool was used for the design and optimisation phases. Then, measurements of the fabricated antenna were undertaken. Parametric studies with several iterations were performed to achieve the best possible results. Second, the effects of the box in which the antenna could be placed were examined as most of such antennas are enclosed by plastic boxes. For this purpose, material properties of a typical industrial box available in the market were studied initially, and the most appropriate material of the box was used in simulations. Finally, a polyamide box with appropriate size was fabricated, and the designed antenna was placed inside the box and the measurements were conducted. The measurement results show that the designed antenna provides resonance at the targeted license-free band with adequate size for industrial remote controllers.Article Citation - WoS: 9Citation - Scopus: 10Modified Resonant Frequency Computation for Tunable Equilateral Triangular Microstrip Patch(Ieice-inst Electronics information Communications Eng, 2010) Aydin, Elif; Can, SultanIn this paper, a new closed form expression is developed to accurately estimate the resonant frequency of an equilateral triangular patch. The proposed computation is also extended to the two-layer structure in order to define the air-gap tuning effect on the resonant frequency. The theory established in this paper is compared with the experimental and theoretical results available in the literature. The results of this study show a considerable improvement achieved over the previous theories within very small percentage errors for almost all cases.Article Citation - WoS: 10Citation - Scopus: 15An Rfid Based Indoor Tracking Method for Navigating Visually Impaired People(Tubitak Scientific & Technological Research Council Turkey, 2010) Oktem, Rusen; Aydin, ElifThis paper tackles the RFID based tracking problem in an obscured indoor environment. The proposed solution is an integral part of a navigation aid for guiding visually impaired people in a store. It uses RF signal strengths and is based on the Bayes Decision Theory. An observation vector is formed by received radio signal strength indication values, transmitted from three transmitters at distinct frequencies in the UHF band. The indoor area is divided into square grids, where each grid is considered as a class. The problem of tracking is expressed as classifying the observed radio signal strengths to the most likely class. A classification rule is formulated by incorporating a priori assumptions appropriate for the studied model. The proposed approach is tested in a laboratory environment. The results prove that the proposed approach is promising in tracking especially when the tracked person is guided by a system.
