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Determination of Measurement Noise, Conductivity Errors and Electrode Mislocalization Effects To Somatosensory Dipole Localization
(Biomedical Research, 2012) Şengül, Gökhan; Baysal, Uğur
Calculating the spatial locations, directions and magnitudes of electrically active sources of human brain by using the measured scalp potentials is known as source localization. An accu rate source localization method requires not only EEG data but also the 3-D positions and number of measurement electrodes, the numerical head model of the patient/subject and the conductivities of the layers used in the head model. In this study we computationally deter mined the effect of noise, conductivity errors and electrode mislocalizations for electrical sources located in somatosensory cortex. We first randomly selected 1000 electric sources in somatosensory cortex, and for these sources we simulated the surface potentials by using av erage conductivities given in the literature and 3-D positions of the electrodes. We then added random noise to measurements and by using noisy data; we tried to calculate the positions of the dipoles by using different electrode positions or different conductivity values. The esti mated electrical sources and original ones are compared and by this way the effect of meas urement noise, electrode mislocalizations and conductivity errors to somatosensory dipole lo calization is investigated. We conclude that for an accurate somatosensory source localization method, we need noiseless measurements, accurate conductivity values of scalp and skull lay ers and the accurate knowledge of 3-D positions of measurement sensors.
Single Camera Photogrammetry System for Eeg Electrode Identification and Localization
(Annals of Biomedical Engineering, 2010) Baysal, Uğur; Şengül, Gökhan
In this study, photogrammetric coordinate measurement and color-based identification of EEG electrode positions on the human head are simultaneously implemented. A rotating, 2MP digital camera about 20 cm above the subject’s head is used and the images are acquired at predefined stop points separated azimuthally at equal angular displacements. In order to realize full automation, the electrodes have been labeled by colored circular markers and an electrode recognition algorithm has been developed. The proposed method has been tested by using a plastic head phantom carrying 25 electrode markers. Electrode locations have been determined while incorporating three different methods: (i) the proposed photogrammetric method, (ii) conventional 3D radiofrequency (RF) digitizer, and (iii) coordinate measurement machine having about 6.5 lm accuracy. It is found that the proposed system automatically identifies electrodes and localizes them with a maximum error of 0.77 mm. It is suggested that this method may be used in EEG source localization applications in the human brain.
Use of Advanced Technologies in a Rf and Microwave Engineering Course
(IEEE, 2010) Aydın, Elif; Çağıltay, Nergiz
In 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.
Distance Laboratory Applications ERRL: A Study on Radio Communication in Electronic Field
(IEEE, 2008) Aydın, Cansu Çiğdem; Özyurt, E.; Aydın, Elif; Çağıltay, Nergiz; Özbek, Mehmet Efe; Alparslan, Ceren; Kara, Ali
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.
Remote Laboratory Development as an Action Research: a Case Study
(2012) Çağıltay, Nergiz; Tokdemir, Gül; Aydın, Elif; Kara, Ali
This work presents a case study about how action research (AR) has been conducted in developing a real-life educational system. An explanation is given of the modified implementation of the classical AR methodology, based on the requirements of a remote laboratory system developed for the vocational training of students in higher education. This study reports a successful implementation of AR stages which established for the development process of a remote laboratory system along with the design of several research questions explored in each step of the system development process. It is believed that the outcomes of the study will help AR implementers to organize their research objectives, more appropriately, by addressing the organizational problems. The results of this study are also expected to guide the AR implementers to better integrate their research in solving domain specific practical problems.
Customizing Ssl Certificate Extensions To Reduce False-Positive Certificate Error/Warning Messages
(International Journal of Information Security Science, 2016) Tarazan, Şafak; Bostan, Atila
In 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.
How To Teach Usage of Equipments in a Remote Laboratory
(IEEE, 2007) Alparslan, Nimet Ceren; Çağıltay, Nergiz; Özen, Mustafa; Aydın, Elif
European 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.
An Indoor Navigation Aid Designed for Visually Impaired People
(2008 34th Annual Conference of IEEE Industrial Electronics, 2008) Öktem, Ruşen; Aydın, Elif; Çağıltay, Nergiz
This 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.
User Study of a New Smart Toy for Children’s Storytelling
(Interactive Learning Environments, 2012) Kara, Nuri; Aydın, Cansu Çiğdem; Çağıltay, Kürşat
This paper introduces the smart storytelling toy (StoryTech) which provides mixed reality environment. StoryTech with a flexible context leads children to tell their imaginative stories. For usability testing of StoryTech, an empirical study was carried out with totally 90 children. The findings indicated that StoryTech created richer experience especially for age groups of five and six in producing stories.
A WEB BASED TRAINING MODULE FOR TEACHING DIGITAL COMMUNICATIONS
(2015) Kara, Ali; Erdem, Cihangir; Özbek, Mehmet Efe; Çağıltay, Nergiz; Aydın, Elif
An interactive module which simulates a digital transmission link from one end to the other has been designed. Using the module, a user may enter a short audio/message signal using microphone of a PC, and then follows processes on the signal at each stage of the digital transmission link. The user can also analyze the signal at every stage of the link, and compare the performance of various modulation schemes used in the link, and finally may see how the audio signal is corrupted by noise in the transmission link. In this way, from source point to destination point of the signal, the user may study various stages such as analog to digital conversion, analysis of effects of Gaussian noise on the message signal.

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