Elektrik Elektronik Mühendisliği Bölümü Koleksiyonu

Permanent URI for this collectionhttps://hdl.handle.net/20.500.11779/1941

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Citation - Scopus: 1
A Microwave Imaging Scheme for Detection of Pulmonary Edema and Hemorrhage
(IEEE, 2022) Ertek, Didem; Kucuk, Gokhan; Bilgin, Egemen
The microwave imaging systems have the potential to present a cost effective and less hazardous alternative to conventional medical imaging techniques. In this paper, a Contrast Source Inversion method based microwave imaging scheme is proposed and tested for the detection of pulmonary edema and hemorrhage. To this end, a realistic human torso phantom is used, and the electromagnetic parameters of the human tissues is determined via Cole-Cole model. The scattered field is simulated via Method of Moments at the operating frequency of 350 MHz, and a 50 dB white Gaussian noise is added to model a realistic measurement setup. The numerical tests performed with the proposed technique suggest that the method can be used to locate the pulmonary edema and hemorrhage, and it is capable of distinguishing these two medical conditions successfully.
Citation - WoS: 1
A Modified Newton Method Formulation for Microwave Imaging
(IEEE, 2020) Coşğun, Sema; Çayören, Mehmet; Bilgin, Egemen; Doğu, Semih
A new variant of Newton type methods has been developed for quantitative microwave imaging. To deal with the ill-posedness of the inverse problems, standard Newton type methods involve a linearization of the so called data equation using the Fréchet derivative with respect to the contrast function. Here, the formulation is expanded to include the object equation, therefore, the formulation seeks to reduce the errors in both the data and the object equations. While this modification does not remove the need to solve forward problem at each step, it nevertheless significantly improves convergence rate and the performance. To assess the efficiency of the proposed technique, numerical simulations with synthetic and experimental data have been carried out. The results demonstrate that the proposed variant outperforms the standard Newton method, and shows comparable performance to the contrast source inversion (CSI) algorithm with fewer iterations.
Citation - WoS: 37
Citation - Scopus: 44
Adaptive Human Force Scaling Via Admittance Control for Physical Human-Robot Interaction
(IEEE, 2021) Başdoğan, Çağatay; Aydın, Yusuf; Hamad, Yahya M.
The goal of this article is to design an admittance controller for a robot to adaptively change its contribution to a collaborative manipulation task executed with a human partner to improve the task performance. This has been achieved by adaptive scaling of human force based on her/his movement intention while paying attention to the requirements of different task phases. In our approach, movement intentions of human are estimated from measured human force and velocity of manipulated object, and converted to a quantitative value using a fuzzy logic scheme. This value is then utilized as a variable gain in an admittance controller to adaptively adjust the contribution of robot to the task without changing the admittance time constant. We demonstrate the benefits of the proposed approach by a pHRI experiment utilizing Fitts’ reaching movement task. The results of the experiment show that there is a) an optimum admittance time constant maximizing the human force amplification and b) a desirable admittance gain profile which leads to a more effective co-manipulation in terms of overall task performance.
Citation - Scopus: 5
An Antipodal Vivaldi Antenna Design for Torso Imaging in a Coupling Medium
(IEEE, 2021) Çayören, Mehmet; Bilgin, Egemen; Joof, Sulayman; Doğu, Semih
An antipodal Vivaldi antenna designed to operate in a coupling medium with a relative dielectric constant of epsilon(r) = 25 for microwave imaging of torso is presented in this paper. The proposed antenna is similar to the conventional antipodal Vivaldi antenna but with optimized parameters to radiate in the desired coupling medium. The antenna has a size of 120x70 mm(2) and operating over 230-1000 MHz frequency bandwidth with a peak gain of 5.42 dBi and peak front-to-back ratio of 143 dB. The designed antenna shows a better performance compared to other antennas used for microwave torso imaging. To assess the actual performance, a realistic human torso phantom is implemented to detect the water accumulation in the lungs, and as the inversion method linear sampling method is used. The 3-D reconstruction results show that the proposed antenna can be a candidate for microwave torso imaging applications.
Citation - WoS: 2
Citation - Scopus: 10
An Fpga Implementation of a Risc-V Based Soc System for Image Processing Applications
(IEEE, 2021) Gholizadehazari, Erfan; Ayhan, Tuba; Ors, Berna
The Laplacian filter is one of the fundamental applications in image processing. In our work, the Laplacian filter has been applied to an image, and both hardware and software implementation of the filter has been studied. Our system consists of an OV7670 Camera module, Nexys 4 DDR FPGA board and VGA monitor to display the processed video stream. Mentioned process has forwarding tasks: camera module captures raw RGB data and writes to RAM, Laplacian filter IP processes raw image and the results written back to memory. VGA modules show output images to monitor. The Laplacian filter part considered in hardware and software implementation is compared in terms of time and area.
Citation - Scopus: 1
An Fpga Implementation of Givens Rotation Based Digital Architecture for Computing Eigenvalues of Asymmetric Matrix
(IEEE, 2022) Köseoğlu, İlayda; Yalçın, Mustak Erhan; Öztürk, Elif; Ayhan, Tuba
This paper proposes the digital circuit design that performs the eigenvalue calculation of asymmetric matrices with realvalued elements. Eigenvalues are computed iteratively through the QR algorithm. In the QR algorithm, the input matrix is factorized into orthogonal Q and upper triangular R matrix, then the RQ product is calculated to obtain an iterated matrix. For a time-efficient QR decomposition process, the Givens Rotation (GR) Principle is utilized to benefit from the parallelization feature. Parallelization is managed by the Systolic Array (SA) architecture that is created by placing Givens Generation (GG) and Row Updates (RU) blocks in a triangle array. In this paper, 4×4 input matrix is used to create a TSA architecture including n-1 diagonal (GG), and (n ∗ (n−1))/2 off-diagonal (RU) modules. In the results section, Givens Rotation is compared with the Gram Schmidt algorithm used in our previous study [1] in terms of error, and area usage.
Citation - Scopus: 1
Design and Fpga Implementation of Uav Simulator for Fast Prototyping
(IEEE, 2023) Aydın, Yusuf; Ayhan, Tuba; Akyavaş , İrfan
As production and advances in motor and battery cell technology progress, unmanned aerial vehicles (UAVs) are gaining more and more acceptance and popularity. Unfortunately, the design and prototyping of UAVs is an expensive and long process. This paper proposes a fast, component based simulation environment for UAVs so that they can be roughly tested without a damage risk. Moreover, the combined effect of individual component choices can be observed with the simulator to reduce design time. The simulator is flexible in the sense that detailed aerodynamic effects and selected components models can be included. In this work, the simulator is proposed, model parameters are extracted for a particular UAV for testing the simulator and it is implemented on an field programmable gate array (FPGA) to increase simulation speed. The simulator calculates battery state of charge (SOC), position, velocity and acceleration of the UAV with gravity, drag, propeller air inflow velocity. The simulator runs on the FPGA fabric of AMD-XCKU13P with simulation steps of 1 ms.
Differential Microwave Imaging of Cerebral Hemorrhage Via Dort Method
(IEEE, 2023) Dilman, İsmail; Bilgin, Egemen; Doğu, Semih
Bleeding in the brain tissues may cause fatal health conditions and continuous monitoring of the change in this blood accumulation becomes important in the first few hours after the incident. The continuous post-event monitoring aims to detect the variations in the size and the shape of the hemorrhage regions. To this end, the human head is illuminated by non-ionizing electromagnetic radiation, and the scattered field is measured in different time instants. The decomposition of the time-reversal (DORT) method is then used as the microwave imaging algorithm to produce an indicator function. The performance of the proposed technique is assessed via numerical simulations involving a realistic human head phantom. The results suggest that the DORT method is capable of detecting the changes in multiple simultaneous cerebral hemorrhage regions successfully.
Citation - WoS: 1
Citation - Scopus: 1
Domain Adaptation Approaches for Acoustic Modeling
(IEEE, 2020) Arısoy, Ebru; Fakhan, Enver
In the recent years, with the development of neural network based models, ASR systems have achieved a tremendous performance increase. However, this performance increase mostly depends on the amount of training data and the computational power. In a low-resource data scenario, publicly available datasets can be utilized to overcome data scarcity. Furthermore, using a pre-trained model and adapting it to the in-domain data can help with computational constraint. In this paper we have leveraged two different publicly available datasets and investigate various acoustic model adaptation approaches. We show that 4% word error rate can be achieved using a very limited in-domain data.
Citation - WoS: 21
Citation - Scopus: 22
Experimental Observation of Temperature and Pressure Induced Frequency Fluctuations in Silicon Mems Resonators
(IEEE, 2021) Zhao, Chun; Mustafazade, Arif; Pandit, Milind; Seshia A, Ashwin; Sobreviela, Guillermo; Zou, Xudong
Silicon MEMS resonators are increasingly being adopted for applications in timing and frequency control, as well as precision sensing. It is well established that a key limitation to performance is associated with sensitivity to environmental variables such as temperature and pressure. As a result, technical approaches to address these factors such as vacuum sealing and ovenization of the resonators in a temperature controlled system have been introduced. However, residual sensitivity to such effects can still serve as a significant source of frequency fluctuations and drift in precision devices. This is experimentally demonstrated in this paper for a precision oven-controlled and vacuum-sealed silicon resonators. The frequency fluctuations of oscillators constructed using two separate nearly-identical co-located resonators on the same chip are analysed and differential frequency fluctuations are examined as a means of reducing the impact of common-mode effects such as temperature and pressure. For this configuration, our results show that the mismatch of temperature and pressure coefficients between the resonators ultimately limits the frequency stability.
Citation - Scopus: 2
Feasibility of Distorted Born Iterative Method for Detecting Early Stage of Heart Failure
(IEEE, 2020) Akıncı, Mehmet Nuri; Bilgin, Egemen; Joof, Sulayman; Doğu, Semih
In this paper, we analyze the feasibility of using microwaves to detect early stage of congestive heart failure, which causes water accumulation in the lungs. To this aim, a slice from realistic human torso phantom, which consists of all human tissues and organs, is considered. Constitutive parameters of the phantom are calculated by multiple order Cole-Cole model at operating frequency. Then, the scattered field is calculated via method of moment and a 30 dB additive white Gaussian noise is added to create a more realistic scenario. In the solution of inverse scattering phase, distorted Born iterative method is utilized. The presented results show the feasibility of the proposed method.
Highlighting of Lecture Video Closed Captions
(IEEE, 2020) Yıldırım, Göktuğ; Öztufan, Huseyin Efe; Arısoy, Ebru
The main purpose of this study is to automatically highlight important regions of lecture video subtitles. Even though watching videos is an effective way of learning, the main disadvantage of video-based education is limited interaction between the learner and the video. With the developed system, important regions that are automatically determined in lecture subtitles will be highlighted with the aim of increasing the learner's attention to these regions. In this paper first the lecture videos are converted into text by using an automatic speech recognition system. Then continuous space representations for sentences or word sequences in the transcriptions are generated using Bidirectional Encoder Representations from Transformers (BERT). Important regions of the subtitles are selected using a clustering method based on the similarity of these representations. The developed system is applied to the lecture videos and it is found that using word sequence representations in determining the important regions of subtitles gives higher performance than using sentence representations. This result is encouraging in terms of automatic highlighting of speech recognition outputs where sentence boundaries are not defined explicitly.
Citation - WoS: 1
Citation - Scopus: 1
İlişkisel Veri Ayrıştırılmasında Model Seçimi
(IEEE, 2019) Kırbız, Serap; Cemgil, Taylan; Hızlı, Çağlar
Abstract—As a fundamental problem in relational data analysis, model selection for relational data factorization is still an open problem. In our work, we propose to estimate model order for mixed membership blockmodels (MMSB) within the generic allocation framework of Bayesian allocation model (BAM). We describe how relational data is represented as Poisson counts of the allocation model, and demonstrate our results both on synthetic and real-world data sets. We believe that the generic allocation perspective promises a generalized model selection solution where we do not only select the model order, but also choose the most appropriate factorization.
Impact of Hardware Sources on Feature Selection for Online Signature Verification
(IEEE, 2020) Ayhan, Tuba; Orak, Remzi
This work analyzes time series features gathered from a touchpad which is a part of online signature verification system. A DTW processing unit is implemented on FPGA to be used in time series analysis. To support different feature groups, this unit can be reconfigured without altering the memory structure. By using this reconfigurable unit, features are evaluated according to the area cost that they introduce. Moreover, a method to predict the value of features for classification is introduced. This way, minimum requirements to implement an online signature verification system on FPGA are partially obtained.
Citation - WoS: 1
Citation - Scopus: 2
Improving the Usage of Subword-Based Units for Turkish Speech Recognition
(IEEE, 2020) Çetinkaya, Gözde; Saraçlar, Murat; Arısoy, Ebru
Subword units are often utilized to achieve better performance in speech recognition because of the high number of observed words in agglutinative languages. In this study, the proper use of subword units is explored in recognition by a reconsideration of details such as silence modeling and position-dependent phones. A modified lexicon by finite-state transducers is implemented to represent the subword units correctly. Also, we experiment with different types of word boundary markers and achieve the best performance by adding a marker both to the left and right side of a subword unit. In our experiments on a Turkish broadcast news dataset, the subword models do outperform word-based models and naive subword implementations. Results show that using proper subword units leads to a relative word error rate (WER) reductions, which is 2.4%, compared with the word level automatic speech recognition (ASR) system for Turkish.
Joint Source Separation and Classiﬁcation Using Variational Autoencoders
(IEEE, 2020) Karamatlı, Ertuğ; Kırbız, Serap; Hızlı, Çağlar
In this paper, we propose a novel multi-task variational auto encoder (VAE) based approach for joint source separation and classification. The network uses a probabilistic encoder for each sources to map the input data to latent space. The latent representation is then used by a probabilistic decoder for the two tasks: source separation and source classification. Throughout a variety of experiments performed on various image and audio datasets, source separation performance of our method is as good as the method that performs source separation under source class supervision. In addition, the proposed method does not require the class labels and can predict the labels.
Live Demo: Design and Fpga Implementation of a Component Level Uav Simulator
(IEEE, 2023) Aydın, Yusuf; Ayhan, Tuba; Akyavaş , İrfan
In this work, we introduce a fast, component based simulation environment for UAVs. The simulator framework is proposed as combination of three sub-models: i. battery, ii. BLDC and propeller, iii. dynamic model. The model parameters are extracted for a particular UAV for testing the simulator. The simulator is implemented on an FPGA to increase simulation speed. The simulator calculates battery SOC, position, velocity and acceleration of the UAV with gravity, drag, propeller air inflow velocity. The simulator runs on the FPGA fabric of XilinxXCKU13P with simulation steps of 1 ms.
Citation - Scopus: 1
Mechanical Design of a Haptic Hand Exoskeleton for Tele-Exploration of Explosive Devices
(IEEE, 2023) Dorantes-Gonzalez, Dante Jorge
There are tasks such as remote exploration and manipulation of explosive objects where high dexterity, accuracy, and practicality are necessary. The proposed haptic hand exoskeleton design uses displacement sensors in both flexion-deflection as well as abduction-adduction to replicate the operator's main three fingers' motion and teleoperate a slave robotic hand for disassembling and disposal of explosive objects. The novel design, component selection, and computer-aided design of the haptic virtual prototype were developed and tested.
Citation - WoS: 3
Citation - Scopus: 5
Negatif Olmayan Gürültü Giderici Değişimli Oto-kodlayıcılar Kullanarak Tek Kanaldan Kaynak Ayrıştırma için Zayıf Etiket Denetimi
(IEEE, 2019) Karamatlı, Ertuğ; Cemgil, Ali Taylan; Kırbız, Serap
Derin öğrenme modelleri, büyük miktarda etiketlenmiş veri bulunduğunda kaynak ayrıştırmada çok başarılı olmaktadır. Bununla birlikte, dikkatlice etiketlenmiş veri kümelerine erişim her zaman mümkün olmamaktadır. Bu bildiride, kısa konuşma karışımlarını ayrıştırmayı öğrenmek için kaynak işaretlerini değil de sadece sınıf bilgisini kullanan zayıf bir denetim önerilmektedir. Negatif olmayan bir modeldeki her bir sınıfla degişimsel bir otomatik kodlayıcıyı (VAE) ilişkilendirilmektedir. Derin evrisimsel VAE’lerin, herhangi bir kaynak sinyaline ihtiyaç duymadan, bir ses karı¸sımındaki karmasık isaretleri kestirmek için önsel bir model sundugu gösterilmektedir. Ayrıstırma sonuçlarının kaynak isaret denetimiyle esit düzeyde oldugu gösterilmektedir.
Parallelization and Performance Analysis of Reversible Circuit Synthesis
(IEEE, 2018) Susam, Ömercan; Arslan, Şuayb Şefik
Rising popularity of quantum computers in the last decade resulted in increased interest paid to reversible circuitsynthesis process. In this work, a popular essential function-based synthesis algorithm known in the literature is parallelized using openMP library. Contrary to conventional way, essential functions are synthesized when needed without keeping a table-lookup library. When the reversible circuit is synthesized in parallel using a double core processor (4 active threads with hyperthearding technology), around 2.6 speed-up is demonstrated relative tothe performance of serial synthesis work. Comparison between serial and parallel synthesis by using common benchmark circuits demonstrated that the performance of the proposed parallel synthesis is always better in the overall operation work load.