Electrical & Electronics Engineering
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Article Towards mmWave Altimetry for UAS: Exploring the Potential of 77 GHz Automotive Radars(Drones, 2024-03-11) Awan, Maaz Ali; Dalveren, Yaser; Kara, Ali; Derawi, MohammadPrecise altitude data are indispensable for flight navigation, particularly during the au tonomous landing of unmanned aerial systems (UASs). Conventional light and barometric sensors employed for altitude estimation are limited by poor visibility and temperature conditions, respec tively, whilst global positioning system (GPS) receivers provide the altitude from the ean sea level (MSL) marred with a slow update rate. To cater to the landing safety requirements, UASs necessitate precise altitude information above ground level (AGL) impervious to environmental conditions. Radar altimeters, a mainstay in commercial aviation for at least half a century, realize these requirements through minimum operational performance standards (MOPSs). More recently, the proliferation of 5G technology and interference with the universally allocated band for radar altimeters from 4.2 to 4.4 GHz underscores the necessity to explore novel avenues. Notably, there is no dedicated MOPS tailored for radar altimeters of UASs. To gauge the performance of a radar al timeter offering for UASs, existing MOPSs are the de facto choice. Historically, frequency-modulated continuous wave (FMCW) radars have been extensively used in a broad spectrum of ranging ap plications including radar altimeters. Modern monolithic millimeter wave (mmWave) automotive radars, albeit designed for automotive applications, also employ FMCW for precise ranging with a cost-effective and compact footprint. Given the technology maturation with excellent size, weight, and power (SWaP) metrics, there is a growing trend in industry and academia to explore their efficacy beyond the realm of the automotive industry. To this end, their feasibility for UAS altimetry remains largely untapped. While the literature on theoretical discourse is prevalent, a specific focus on mmWave radar altimetry is lacking. Moreover, clutter estimation with hardware specifications of a pure look-down mmWave radar is unreported. This article argues the applicability of MOPSs for commercial aviation for adaptation to a UAS use case. The theme of the work is a tutorial based on a simplified mathematical and theoretical discussion on the understanding of performance metrics and inherent intricacies. A systems engineering approach for deriving waveform specifications from operational requirements of a UAS is offered. Lastly, proposed future research directions and insights are included.Article A Radio Frequency Fingerprinting-Based Aircraft Identification Method Using ADS-B Transmissions(Aerospace, 2024-03-17) Gürer, Gürsu; Dalveren, Yaser; Kara, Ali; Derawi, MohammadThe automatic dependent surveillance broadcast (ADS-B) system is one of the key components of the next generation air transportation system (NextGen). ADS-B messages are transmitted in unencrypted plain text. This, however, causes significant security vulnerabilities, leaving the system open to various types of wireless attacks. In particular, the attacks can be intensified by simple hardware, like a software-defined radio (SDR). In order to provide high security against such attacks, radio frequency fingerprinting (RFF) approaches offer reasonable solutions. In this study, an RFF method is proposed for aircraft identification based on ADS-B transmissions. Initially, 3480 ADS-B samples were collected by an SDR from eight aircrafts. The power spectral density (PSD) features were then extracted from the filtered and normalized samples. Furthermore, the support vector machine (SVM) with three kernels (linear, polynomial, and radial basis function) was used to identify the aircraft. Moreover, the classification accuracy was demonstrated via varying channel signal-to-noise ratio (SNR) levels (10–30 dB). With a minimum accuracy of 92% achieved at lower SNR levels (10 dB), the proposed method based on SVM with a polynomial kernel offers an acceptable performance. The promising performance achieved with even a small dataset also suggests that the proposed method is implementable in real-world applications.Article A Hybrid-Flipped Classroom Approach: Students’ Perception and Performance Assessment(Ingeniería e Investigación, 2023-08-04) Yalçınkaya Gökdoğan, Bengisu; Çoruk, Remziye Büşra; Benzaghta, Mohamed; Kara, AliThis study presents an improved hybrid-flipped classroom (hybrid-FC) education method based on technology-enhanced learning (TEL) along with diluted classes for a course on probability and random processes in engineering. The proposed system was implemented with the participation of two student groups who alternated weekly between attending face-to-face activities and fully online classes as a sanitary measure during the pandemic. The education model was combined with the flipped classroom (FC) approach in order to improve the quality of learning and address the negative effects of remote education. Before the lessons, the students studied the course material, filled a question form, and then took a low-stake online quiz. Then, the students attended a session where the questions reported in the forms were discussed, and they took an online problem-solving session followed by an individual quiz. Class sessions were available to both online and face-to-face students, as well as in the form of video recordings for anyone who missed lessons. Qualitatively and quantitatively, the proposed education method proved to be more effective and comprehensive than conventional online methodologies. The students' performances were evaluated via quizzes and exams measuring the achievement of the course learning outcomes (CLOs). Weekly pre/post-tests were applied to examine the students’ progress in each topic. Midterm and final exams were planned to measure the level of success for all course topics. Additionally, the students' perception was assessed with questionnaires and face-to-face interviews. A performance assessment showed an apparent increase in the success rate, and the students' perception was found to be positive. Este estudio presenta un método educativo mejorado de aula invertida híbrida (hybrid-FC) basado en el aprendizaje mejorado por tecnología (TEL) junto con clases diluidas para un curso sobre probabilidad y procesos aleatorios. El sistema propuesto se implementó con la participación de dos grupos de estudiantes que alternaban semanalmente entre asistir a actividades presenciales y totalmente en línea como una medida sanitaria durante la pandemia. El modelo educativo se combinó con el enfoque de aula invertida (FC) para mejorar la calidad del aprendizaje y hacer frente a los efectos negativos de la educación a distancia. Antes de asistir a clase, los estudiantes estudiaban el material del curso, completaban un formulario de preguntas y luego tomaban un quiz en línea de bajo impacto. Luego, los estudiantes asistían a una sesión en la que se discutían las respuestas en los formularios, y tomaban una sesión en línea de resolución de problemas, seguida de un cuestionario individual. Las clases estaban disponibles tanto para los estudiantes en línea como para aquellos que asistían de forma presencial; también había grabaciones de video para quien faltara a clases. Cualitativa y cuantitativamente, el método educativo propuesto demostró ser más efectivo y completo que los métodos online convencionales. El desempeño de los estudiantes se evaluó mediante cuestionarios y exámenes que medían el logro de los resultados de aprendizaje del curso (CLO). Se realizaron exámenes previos y posteriores semanales para examinar el progreso de los estudiantes en cada tema. Se planificaron exámenes parciales y finales para medir el nivel de éxito de todos los temas del curso. Además, la percepción de los estudiantes se evaluó con cuestionarios y entrevistas presenciales. La evaluación del desempeño mostró un aumento aparente en la tasa de éxito, y se encontró que la opinión de los estudiantes era positiva.Article Deployment and Implementation Aspects of Radio Frequency Fingerprinting in Cybersecurity of Smart Grids(Electronics, 2023-12-06) Awan, Maaz Ali; Dalveren, Yaser; Çatak, Ferhat Özgür; Kara, AliSmart grids incorporate diverse power equipment used for energy optimization in intelligent cities. This equipment may use Internet of Things (IoT) devices and services in the future. To ensure stable operation of smart grids, cybersecurity of IoT is paramount. To this end, use of cryptographic security methods is prevalent in existing IoT. Non-cryptographic methods such as radio frequency fingerprinting (RFF) have been on the horizon for a few decades but are limited to academic research or military interest. RFF is a physical layer security feature that leverages hardware impairments in radios of IoT devices for classification and rogue device detection. The article discusses the potential of RFF in wireless communication of IoT devices to augment the cybersecurity of smart grids. The characteristics of a deep learning (DL)-aided RFF system are presented. Subsequently, a deployment framework of RFF for smart grids is presented with implementation and regulatory aspects. The article culminates with a discussion of existing challenges and potential research directions for maturation of RFF.Article Convolutional Neural Network-Based Vehicle Classification in Low-Quality Imaging Conditions for Internet of Things Devices(Sustainability, 2023-11-24) Maiga, Bamoye; Dalveren, Yaser; Kara, Ali; Derawi, MohammadVehicle classification has an important role in the efficient implementation of Internet of Things (IoT)-based intelligent transportation system (ITS) applications. Nowadays, because of their higher performance, convolutional neural networks (CNNs) are mostly used for vehicle classification. However, the computational complexity of CNNs and high-resolution data provided by high-quality monitoring cameras can pose significant challenges due to limited IoT device resources. In order to address this issue, this study aims to propose a simple CNN-based model for vehicle classification in low-quality images collected by a standard security camera positioned far from a traffic scene under low lighting and different weather conditions. For this purpose, firstly, a new dataset that contains 4800 low-quality vehicle images with 100 × 100 pixels and a 96 dpi resolution was created. Then, the proposed model and several well-known CNN-based models were tested on the created dataset. The results demonstrate that the proposed model achieved 95.8% accuracy, outperforming Inception v3, Inception-ResNet v2, Xception, and VGG19. While DenseNet121 and ResNet50 achieved better accuracy, their complexity in terms of higher trainable parameters, layers, and training times might be a significant concern in practice. In this context, the results suggest that the proposed model could be a feasible option for IoT devices used in ITS applications due to its simple architecture.Article Modelling and Design of Pre-Equalizers for a Fully Operational Visible Light Communication System(Sensors, 2023-06-14) Bostanoğlu, Murat; Dalveren, Yaser; Çatak, Ferhat Özgür; Kara, AliNowadays, Visible Light Communication (VLC) has gained much attention due to the significant advancements in Light Emitting Diode (LED) technology. However, the bandwidth of LEDs is one of the important concerns that limits the transmission rates in a VLC system. In order to eliminate this limitation, various types of equalization methods are employed. Among these, using digital pre-equalizers can be a good choice because of their simple and reusable structure. Therefore, several digital pre-equalizer methods have been proposed for VLC systems in the literature. Yet, there is no study in the literature that examines the implementation of digital pre-equalizers in a realistic VLC system based on the IEEE 802.15.13 standard. Hence, the purpose of this study is to propose digital pre-equalizers for VLC systems based on the IEEE 802.15.13 standard. For this purpose, firstly, a realistic channel model is built by collecting the signal recordings from a real 802.15.13-compliant VLC system. Then, the channel model is integrated into a VLC system modeled in MATLAB. This is followed by the design of two different digital pre-equalizers. Next, simulations are conducted to evaluate their feasibility in terms of the system’s BER performance under bandwidth-efficient modulation schemes, such as 64-QAM and 256-QAM. Results show that, although the second pre-equalizer provides lower BERs, its design and implementation might be costly. Nevertheless, the first design can be selected as a low-cost alternative to be used in the VLC system.Article LPWAN Cyber Security Risk Analysis: Building a Secure IQRF Solution(Sensors, 2023-02-12) Bouzidi, Mohammed; Amro, Ahmed; Dalveren, Yaser; Cheikh, Faouzi Alaya; Derawi, MohammadLow-power wide area network (LPWAN) technologies such as IQRF are becoming increasingly popular for a variety of Internet of Things (IoT) applications, including smart cities, industrial control, and home automation. However, LPWANs are vulnerable to cyber attacks that can disrupt the normal operation of the network or compromise sensitive information. Therefore, analyzing cybersecurity risks before deploying an LPWAN is essential, as it helps identify potential vulnerabilities and threats as well as allowing for proactive measures to be taken to secure the network and protect against potential attacks. In this paper, a security risk analysis of IQRF technology is conducted utilizing the failure mode effects analysis (FMEA) method. The results of this study indicate that the highest risk corresponds to four failure modes, namely compromised end nodes, a compromised coordinator, a compromised gateway and a compromised communication between nodes. Moreover, through this methodology, a qualitative risk evaluation is performed to identify potential security threats in the IQRF network and propose countermeasures to mitigate the risk of cyber attacks on IQRF networksArticle Investigating the Impact of Two Major Programming Environments on the Accuracy of Deep Learning-Based Glioma Detection from MRI Images(Diagnostics, 2023-02-09) Yılmaz, Vadi Su; Akdağ, Metehan; Dalveren, Yaser; Doruk, Reşat Özgür; Kara, Ali; Soylu, AhmetBrain tumors have been the subject of research for many years. Brain tumors are typically classified into two main groups: benign and malignant tumors. The most common tumor type among malignant brain tumors is known as glioma. In the diagnosis of glioma, different imaging technologies could be used. Among these techniques, MRI is the most preferred imaging technology due to its high-resolution image data. However, the detection of gliomas from a huge set of MRI data could be challenging for the practitioners. In order to solve this concern, many Deep Learning (DL) models based on Convolutional Neural Networks (CNNs) have been proposed to be used in detecting glioma. However, understanding which CNN architecture would work efficiently under various conditions including development environment or programming aspects as well as performance analysis has not been studied so far. In this research work, therefore, the purpose is to investigate the impact of two major programming environments (namely, MATLAB and Python) on the accuracy of CNN-based glioma detection from Magnetic Resonance Imaging (MRI) images. To this end, experiments on the Brain Tumor Segmentation (BraTS) dataset (2016 and 2017) consisting of multiparametric magnetic MRI images are performed by implementing two popular CNN architectures, the three-dimensional (3D) U-Net and the V-Net in the programming environments. From the results, it is concluded that the use of Python with Google Colaboratory (Colab) might be highly useful in the implementation of CNN-based models for glioma detection. Moreover, the 3D U-Net model is found to perform better, attaining a high accuracy on the dataset. The authors believe that the results achieved from this study would provide useful information to the research community in their appropriate implementation of DL approaches for brain tumor detection.Item A New RF and Microwave Engineering Course Enriched With Advanced Technologies(2010-02-08) AYDIN, Elif; ÇAĞILTAY, NergizIn this study, a curriculum model including recent developments and technologies in the Radio Frequency (RF) and Microwave Engineering field by using a blended approach is proposed. This study covers the description of the content of theoretical and hands on applications, the integration model of the technological tools into the proposed curriculum, and the instructional approaches used in the new course design. The main goal of the course is to prepare students for future professional careers in RF and Microwave Engineering by supporting them with new instructional technologies. The secondary goal of the course is to better prepare the students for the sequence of senior courses in the Electrical and Electronics Engineering program of Atilim University. The course is structured with a balance between theory and laboratory, including remote and in lab measurement experiments as well as modeling and designing microwave components by means of computer tools and design fabrication. The newly designed course is implemented at the Atilim University. The study also reports the first semester implementation.Item Maintenance, sustainability and extendibility in virtual and remote laboratories(Social and Behavioral Sciences, 2011-08-10) KARA, Ali; ÖZBEK, Mehmet Efe; ÇAĞILTAY, Nergiz; 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.Item A REMOTE LABORATORY FOR TRAINING IN RADIO COMMUNICATIONS: ERRL(IEEE, 2007-08-10) KARA, Ali; AYDIN, Elif; ÖKTEM, Ruşen; ÇAĞILTAY, NergizThis paper presents, first, a short survey of remote laboratory initiatives in electrical and computer engineering, and then discusses design and development phases of remote laboratory environment on radio communications, the ERRL (European Remote Radio Laboratory). As being the first attempt in establishing of such a large scale remote laboratory on radio communications, ERRL enables access to high technology RF equipments and setups through the Internet. The software structure, target groups and experimental set ups of ERRL are shortly discussed. First attempts on implementation of pilot experiments are discussed.Item HOW ASSESSMENT SYSTEM OF AN OPEN SOURCE LEARNING MANAGEMENT SYSTEM CAN BE INTEGRATED TO A REMOTE LABORATORY APPLICATION? PROBLEMS AND SOLUTIONS(IEEE, 2007-08-10) AYDIN, Cansu Çiğdem; ÇAĞILTAY, NergizMost 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. In 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.Item How to Teach Usage of Equipments in a Remote Laboratory(IEEE, 2007-08-10) ALPARSLAN, Nimet Ceren; ÇAĞILTAY, Nergiz; ÖZEN, Mustafa; AYDIN, ElifEuropean Remote Radio Laboratory (ERRL) is an e learning project for students, teachers and technicians of the universities who will use the very important devices of this laboratory remotely. These devices are very expensive to buy and can be broken easily while they have been using by the people who does not really know how to use them professionally. As a solution we have developed an e-learning system which aims to support the ERRL learners while studying on how to use equipments in the system. The system is developed according to the electronic performance support systems (EPSS) approach. An EPSS is a computer-based, well structured system which improves the performance of individuals. It is an electronic infrastructure that contains, stores and distributes personal (individual) or corporate knowledge to enable people to reach necessary levels of performance in the fastest possible time and with minimum teaching support of other people. This paper discusses how the content for such a system is developed and how this content is interactively used in the EPSS platform. The technical details of the developed EPSS are also discussed in this study. We believe that this paper will help instructional system designers for designing different alternatives to improve learners’ performance.Item Distance Laboratory Applications ERRL: A Study on Radio Communication in Electronic Field(IEEE, 2008-05-24) AYDIN, Cansu Çiğdem; ÖZYURT, E.; AYDIN, Elif; ÇAĞILTAY, Nergiz; ÖZBEK, Mehmet Efe; ALPARSLAN, Ceren; KARA, AliIn 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.Item Use of Advanced Technologies in a RF and Microwave Engineering Course(IEEE, 2010-04-16) AYDIN, Elif; ÇAĞILTAY, NergizIn RF and Microwave Engineering course, usually students struggle to build connections between the theory they have learned and practical applications in the laboratory. The laboratory applications are usually very limited for hands on experience since the high cost and maintenance requirements of the equipment. Additionally, new engineers need to know how to use at least one engineering design tool in order to practice designing RF components, circuits, or antennas. In this study, a curriculum model including recent developments and technologies in the RF and Microwave Engineering field by addressing above problems of the course is proposed. This study covers the description of the content of theoretical and hands on applications, the integration model of the technological tools into the proposed curriculum, and the instructional approaches used in the new course design which covers the use of a remote laboratory environment, Concept Maps and an engineering design tool. The course is structured with a balance between theory and laboratory, including remote and in lab measurement experiments as well as modeling and designing microwave components by means of computer tools and design fabrication. The newly designed course is implemented at the Atilim University. The first semester implementation shows promising results.Item An Indoor Navigation Aid Designed for Visually Impaired People(2008 34th Annual Conference of IEEE Industrial Electronics, 2008-08-09) ÖKTEM, Ruşen; AYDIN, Elif; ÇAĞILTAY, NergizThis work introduces the hardware architecture and general principles of a portable indoor navigation system for guiding visually impaired people. It operates through wireless communication between a compact hardware interface unit carried by the user, a central processing unit and an active RFID unit. The RFID unit collects signals as regard to the position of the user, the central system processes those signals to estimate the position of the user and proposes a route and direction for the user to follow, whereas hardware interface unit provides interaction. The orienteering of the user is obtained by a tactile compass.Item Design and development of a remote and virtual environment for experimental training in Electrical and Electronics Engineering(2010 9th International Conference on Information Technology Based Higher Education and Training (ITHET), 2010-05-09) KARA, Ali; AYDIN, Elif; ÖZBEK, Mehme Efe; ÇAĞILTAY, NergizEuropean Remote Radio Laboratory (ERRL) has been developed by the support of European Commission. It intends to provide remote access to high cost devices remotely, and perform experiments in radio frequency (RF), communications and microwave domains of Electrical and Electronics Engineering. The system has been operational for two years, and been integrated into curriculum of some courses. In this work, the hardware and software structures of the system are presented. Then, experimental content and the motivations in the design of the system are discussed.Item Customizing SSL Certificate Extensions to Reduce False-Positive Certificate Error/Warning Messages(International Journal of Information Security Science, 2016-08-04) TARAZAN, Şafak; BOSTAN, AtilaIn today’s Internet world, X.509 certificates are commonly used in SSL protocol to provide security for web-based services by server/client authentication and secure communication. Although SSL protocol presents a technical basis, this web security largely depends on user awareness of security measures as well. There are significant number of scientific studies in the literature reporting that the count of invalid or self-signed certificate usage in today’s Internet can not be overlooked. At the same time, quite a number of studies place emphasis on the acquired indifference towards certificate warning messages which are popped up by web browsers when visiting web pages with invalid or self-signed certificates. In this study, with the importance of user’s daily practices in developing habits in mind, we studied a modification of X.509 certificates in order to reduce the number of false-positive certificate-warning pop ups in order to reduce gaining faulty usage habit of invalid certificates.Item Distance Laboratory Applications ERRL: A Study on Radio Communication in Electronic Field(Optimization of Electrical and Electronic Equipment, 2008-08-04) AYDIN, Cansu Çiğdem; ÖZYURT, Erdem; AYDIN, Elif; ÇAĞILTAY, Nergiz; ÖZBEK, Efe; ALPARSLAN, CerenIn 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.Item Smart Toy Based Learning(Handbook of Research on Educational Communications and Technology, 2014-05-04) ÇAĞILTAY, Kürşat; KARA, Nuri; AYDIN, Cansu ÇiğdemThis chapter examines the general characteristics of and related recent research on smart toys. Smart toys can be defined as new forms of toys featuring both tangible objects and electronic components that facilitate two-way child–smart toy interactions to carry out pur poseful tasks. In this chapter, smart toy based learning projects are discussed and the char acteristics of smart toys as cognitive tools to facilitate learning are analyzed. This chapter also covers the relationship between smart toys and children’s developmental stages—with a particular focus on motivation—in order to understand smart toys’ potential effects on children.