Electrical - Electronic Engineering / Elektrik - Elektronik Mühendisliği
Permanent URI for this collectionhttps://hdl.handle.net/11147/11
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Article Citation - WoS: 9Citation - Scopus: 12Intensity and Phase Stacked Analysis of a 40-Otdr System Using Deep Transfer Learning and Recurrent Neural Networks(Optica Publishing Group, 2023) Kayan, Ceyhun Efe; Yüksel Aldoğan, Kıvılcım; Gümüş, AbdurrahmanDistributed acoustic sensors (DAS) are effective apparatuses that are widely used in many application areas for recording signals of various events with very high spatial resolution along optical fibers. To properly detect and recognize the recorded events, advanced signal processing algorithms with high computational demands are crucial. Convolutional neural networks (CNNs) are highly capable tools to extract spatial information and are suitable for event recognition applications in DAS. Long short-term memory (LSTM) is an effective instrument to process sequential data. In this study, a two-stage feature extraction methodology that combines the capabilities of these neural network architectures with transfer learning is proposed to classify vibrations applied to an optical fiber by a piezoelectric transducer. First, the differential amplitude and phase information is extracted from the phasesensitive optical time domain reflectometer (40-OTDR) recordings and stored in a spatiotemporal data matrix. Then, a state-of-the-art pre-trained CNN without dense layers is used as a feature extractor in the first stage. In the second stage, LSTMs are used to further analyze the features extracted by the CNN. Finally, a dense layer is used to classify the extracted features. To observe the effect of different CNN architectures, the proposed model is tested with five state-of-the-art pre-trained models (VGG-16, ResNet-50, DenseNet-121, MobileNet, and Inception-v3). The results show that using the VGG-16 architecture in the proposed framework manages to obtain a 100% classification accuracy in 50 trainings and got the best results on the 40-OTDR dataset. The results of this study indicate that pre-trained CNNs combined with LSTM are very suitable to analyze differential amplitude and phase information represented in a spatiotemporal data matrix, which is promising for event recognition operations in DAS applications. (c) 2023 Optica Publishing GroupArticle Citation - WoS: 1Citation - Scopus: 1Experimental Demonstration of a Transient Grating Controlled All-Optical Switch(IOP Publishing, 2023) Akın, Osman; Dinleyici, Mehmet SalihWe demonstrate an on-fiber all-optical switching device based on a transient grating formed by the interference of control laser pulses in a Kerr-type nonlinear material placed in the evanescent region of the fiber. The device can operate in two distinctive modes. First, switching/coupling among the fiber modes using bulk index modulation was investigated and an efficiency of about %0.55 @852 nm was measured. Second, by exploiting Four Wave Mixing (FWM), an all-optical switching that transfers power among light signals with wavelengths of λ 1 = 440 nm and λ 2 = 663 nm was achieved by quasi-phase-matching and fRequency matching in a nonlinear thin polymeric film. The results prove that the introduced switching structure may have the potential to be used in integrated photonic applications such as intensity modulators or controllable couplers.Article Citation - WoS: 6Citation - Scopus: 7Human-Robot Interfaces of the Neuroboscope: a Minimally Invasive Endoscopic Pituitary Tumor Surgery Robotic Assistance System(ASME, 2021) Dede, Mehmet İsmet Can; Kiper, Gökhan; Ayav, Tolga; Özdemirel, Barbaros; Tatlıcıoğlu, Enver; Hanalioğlu, Şahin; Işıkay, İlkayEndoscopic endonasal surgery is a commonly practiced minimally invasive neurosurgical operation for the treatment of a wide range of skull base pathologies including pituitary tumors. A common shortcoming of this surgery is the necessity of a third hand when the endoscope has to be handled to allow active use of both hands of the main surgeon. The robot surgery assistant NeuRoboScope system has been developed to take over the endoscope from the main surgeon's hand while providing the surgeon with the necessary means of controlling the location and direction of the endoscope. One of the main novelties of the NeuRoboScope system is its human-robot interface designs which regulate and facilitate the interaction between the surgeon and the robot assistant. The human-robot interaction design of the NeuRoboScope system is investigated in two domains: direct physical interaction (DPI) and master-slave teleoperation (MST). The user study indicating the learning curve and ease of use of the MST is given and this paper is concluded via providing the reader with an outlook of possible new human-robot interfaces for the robot assisted surgery systems.Article Citation - WoS: 12Citation - Scopus: 14A Molecular Communication Perspective on Airborne Pathogen Transmission and Reception Via Droplets Generated by Coughing and Sneezing(IEEE, 2021) Güleç, Fatih; Atakan, BarışInfectious diseases spread via pathogens such as viruses and bacteria. Airborne pathogen transmission via droplets is an important mode for infectious diseases. In this paper, the spreading mechanism of infectious diseases by airborne pathogen transmission between two humans is modeled with a molecular communication perspective. An end-to-end system model which considers the pathogen-laden cough/sneeze droplets as the input and the infection state of the human as the output is proposed. This model uses the gravity, initial velocity and buoyancy for the propagation of droplets and a receiver model which considers the central part of the human face as the reception interface is proposed. Furthermore, the probability of infection for an uninfected human is derived by modeling the number of propagating droplets as a random process. The numerical results reveal that exposure time affects the probability of infection. In addition, the social distance for a horizontal cough should be at least 1.7 m and the safe coughing angle of a coughing human to infect less people should be less than -25 degrees.Article Citation - WoS: 5Citation - Scopus: 6Sanal Elektrik Makinaları Laboratuarı: Senkron Jeneratör Deneyleri(Gazi Üniversitesi, 2010) Bekiroğlu, Erdal; Bayrak, AlperBu çalışmada, senkron jeneratör deneylerinin bilgisayar ortamında yapılabilmesini sağlayan sanal bir elektrik makinaları laboratuar aracı geliştirilmiştir. Geliştirilen araç ile senkron jeneratörlere ait boş çalışma, kısa devre, yüklü çalışma ve paralel bağlama deneyleri yapılmaktadır. Her deney için ayrı bir deney sayfası açılarak, deneyin yapılışı, bağlantı şeması, tablo ve grafikler gösterilmektedir. C#.NET platformu kullanılarak geliştirilen sanal laboratuar aracı kullanıcı dostu olarak tasarlanmıştır. Benzetim çalışmaları için jeneratörün modeli ve pratik deneylerden yararlanılmıştır. Geliştirilen sanal laboratuar aracı, konu ile ilgili eğitim alan öğrencilerin senkron jeneratörleri daha iyi kavramasına yardımcı olacak, gerekli laboratuar donanımlarının kurulmadığı birimlerde öğrencilere bilgisayar ortamında deneyleri yapma olanağı sağlayacaktır.Article Citation - WoS: 14Citation - Scopus: 15A Droplet-Based Signal Reconstruction Approach To Channel Modeling in Molecular Communication(Institute of Electrical and Electronics Engineers Inc., 2021) Güleç, Fatih; Atakan, BarışIn this paper, a novel droplet-based signal reconstruction (SR) approach to channel modeling, which considers liquid droplets as information carriers instead of molecules in the molecular communication (MC) channel, is proposed for practical sprayer-based macroscale MC systems. These practical MC systems are significant, since they can be used in order to investigate airborne pathogen transmission with biological sensors due to the similar mechanisms of sneezing/coughing and sprayer. Our proposed approach takes a two-phase flow which is generated by the interaction of droplets in liquid phase with air molecules in gas phase into account. Two-phase flow is combined with the SR of the receiver (RX) to propose a channel model. The SR part of the model quantifies how the accuracy of the sensed molecular signal in its reception volume depends on the sensitivity response of the RX and the adhesion/detachment process of droplets. The proposed channel model is validated by employing experimental data. IEEEConference Object Citation - WoS: 15Citation - Scopus: 20Adaptive Control of Redundant Robot Manipulators With Sub-Task Objectives [proceedings Paper](Institute of Electrical and Electronics Engineers Inc., 2008) Tatlıcıoğlu, Enver; Braganza, David; Burg, Timothy C.; Dawson, Darren M.In this paper, adaptive control of kinematically redundant robot manipulators is considered. An end-effector tracking controller is designed and the manipulator's kinematic redundancy is utilized to integrate a general sub-task controller for self-motion control. The control objectives are achieved by designing a feedback linearizing controller that includes a least-squares estimation algorithm to compensate for the parametric uncertainties.Conference Object Citation - Scopus: 1Interference Management for Multiuser Multiantenna Ofdma Underlaying Device-To Communications(IEEE, 2017) Özbek, Berna; Pischella, Mylene; Le Ruyet, DidierUnderlaying device-to-device (D2D) transmission in cellular wireless systems is one of the promising transmission techniques for fifth generation (5G) and beyond 5G applications. Nevertheless, the interference between the D2D pairs, the interference from cellular users to D2D receivers and the interference that affects the cellular communications should be mitigated to increase the overall system performance. In this paper, we propose interference management techniques for D2D underlaying communications in multiuser multiantenna orthogonal frequency division multiple access (OFDMA) systems. Our goal is to increase the data rate of both the cellular users and D2D pairs by performing interference management in frequency, power and spatial dimensions. The performance evaluations illustrate the effectiveness of the proposed algorithm in terms of average data rate and average transmitted power for both cellular users and D2D pairs.Conference Object Citation - WoS: 3Citation - Scopus: 3Space-Frequency Grouping Based Key Extraction for Mimo-Ofdm Systems(IEEE, 2017) Topal, Ozan Alp; Karabulut Kurt, Güneş; Özbek, BernaLatest developments in wireless communication networks push the limits of conventional security methods. Security can be improved with a secret key that is dynamically generated based on the surrounding physical environment. With this objective, physical layer security approaches can be implemented by means of simple signal processing methods. In this paper, we propose novel key extraction approaches based on spatial and frequency characteristics of the wireless environment. In a 2x2 MIMO-OFDM system, low key disagreement rates and key error rates are observed, proving the potential of physical layer key extraction techniques.Article Citation - WoS: 10Citation - Scopus: 10The Effect of Additional Telerounding on Postoperative Outcomes, Patient and Surgeon Satisfaction Rates in the Patients Who Underwent Percutaneous Nephrolithotomy(Iniestares, S.A., 2019) Aydoğdu, Özgü; Şen, Volkan; Yarımoğlu, Serkan; Aydoğdu, Canan; Bozkurt, İbrahim H.; Yonguç, TarıkINTRODUCTION: We wanted to investigate the potential effect of additional telerounding system on postoperative outcomes, patient and surgeon satisfaction rates in the patients who underwent percutaneous nephrolithotomy (PNL). METHODS: Eighty patients who underwent PNL were included in the study. The patients were randomly divided to two groups. Group 1 included 40 patients who were followed-up with standard rounds and group 2 included 40 patients who were followed-up with telerounding in addition to standard rounds. Patient and surgeon satisfaction rates were assessed with a visual analog scale (VAS) where 0 point represents very dissatisfied and 100 points very satisfied. RESULTS: Mean time of preoperative telerounding visit was 3.65 +/- 0.59 (2-4) minutes. Mean time of telerounding visits on the postoperative 1st and 2nd days was 3.80 +/- 0.62 and 2.9 +/- 0.91 minutes respectively. The VAS score evaluating the surgeon's satisfaction rate for telerounding was 91 +/- 11.2 and patients expressed a high level of satisfaction with 72.5%. CONCLUSION: The use of additional telerounding in urological patient care provides high satisfaction rates for both the patients and the surgeon. However the findings of the present study don't underestimate the importance of personal surgeon-patient interaction.