Ahmet Özkurt

The electromagnetic shielding properties of some conductive knitted fabrics produced on single or double needle bed of a flat knitting machine

In recent years, the use of electrical and electronic devices has grown rapidly. These devices cause electromagnetic interferences, which could threaten human life. In order to solve this problem, intensive research to develop textile surfaces having electromagnetic shielding properties continues. In this paper, we study textile surfaces knitted with conductive copper and stainless steel wires wrapped with acrylic yarns and also core yarns produced by using conductive yarns to test the electromagnetic shielding properties of the fabrics. It was concluded that the knitted structure of the fabrics affected the electromagnetic shielding effectiveness (EMSE). Besides, the fabrics knitted on a double needle bed of the knitting machine with higher amounts of conductive yarns and unit weights could not provide the targeted improvement in the EMSE values with respect to the fabrics produced on a single needle bed of the knitting machine.

Multiple robot path planning for robot soccer

The Robot World Cup Initiative (RoboCup) is an international joint project to promote AI, robotics, and related field. It provides a standard platform for robotic soccer game which includes a vision system, a strategic play algorithm and small mobile robots. The aim of the vision system for RoboCup small robot league is to track and predict the motion states of 6 agents and a ball, and send the states information to the Artificial Intelligence module. This paper presents a design and implementation of a real-time, robust global vision system. The two main efforts are realized in this study, design and implementation of multi robot structure and the construction and testing of the tracking and path planning algorithm. In the tracking phase, the color-based segmentation is used to locate the interesting objects in the image; the blob analysis is adopted to calculate the positions of the objects in the image and the noise is filtered out; and the linear filter is adopted to track and predict information of the states. It has been planned that the information gathered using this study can be used in multiple agent robotics applications.

The electromagnetic shielding of textured steel yarn based woven fabrics used for clothing

The electromagnetic shielding effectiveness (EMSE) of herringbone, whipcord, barathea, and crêpe woven fabrics, which are twill and sateen derivatives, woven with textured steel yarns has not been investigated so far. Therefore, in this research, textured stainless steel yarn, which has soft feeling and flexibility, required properties for clothing fabrics, was selected as a conductive yarn to produce conductive fabrics whose weaves are twill, twill and sateen derivatives. The EMSE of these common clothing fabrics woven with different conductive yarn densities were measured by free space measurement technique with different antenna polarizations, because of the possibility to obtain measurements for a large bandwidth. It was observed that all conductive clothing woven fabric samples shielded well in medium and high frequency bands, which contain 900 MHz GSM, 1800 MHz GSM, 2100 MHz 3G, and 2400 MHz Wi-Fi bands. Most of the samples give acceptable EMSE values up to 40 dB at certain frequencies. The EMSE of fabric samples would remain almost the same, although conductive yarn density changed, because of diagonally or symmetrically arranged conductive yarn floats in fabric structures. The EMSE characteristics of different weave types are investigated and it is seen that when the yarn floats arrangement is changed the EMSE characteristic changes. And also, it is observed that measurements of fabrics, positioned so that the weft yarns were parallel to the antenna polarization are similar to those of fabrics, positioned so that the weft yarns were vertical to the antenna polarization.

Interactive education system for medicine and engineering using three dimensional virtual environments

Three dimensional modeling and simulation software are becoming more widespread in many fields with the emphasis on engineering, military and medical applications. The main important features of these applications are fast prototyping, simulation of scientific and engineering problems under different conditions and interactive user interface. Therefore, an opportunity for a fast visual education course and understanding the physical and mathematical reasons lying under the problems is presented to engineers, military and scientific researches in the respective fields. The main requirements of these applications are high performance computer systems and user interfaces that feature an easier interaction. The fast developing computer architecture maintains the necessary architecture and enables the applications to improve. Considering above and the expectations of Dokuz Eylül University Faculty of Medicine, the development of a virtual environment software that will model the predefined medical processes with user interaction has been aimed. In this paper, the 1. section is reserved for basic concepts and field applications. The hardware and software infrastructure and algorithm development process we used are presented in the 2. section. The 3. section presents the completed stages and first results of our application. The final section which is the 4. section is reserved for the conclusion and future work.

Folded systolic array based MVDR beamformer

Optimal weight extraction by using beamforming algorithms based on systolic structures have been the subject of various researches since the well-known article presented by Gentleman and Kung on recursive least squares systolic arrays. Systolic algorithms are parallel and fully pipelined structures, this feature improves the performance of the beamforming algorithms and the system. This paper presents a folded MVDR algorithm running on a systolic array structure. The folded structure of the systolic array reduces the die size of the hardware implementation.

Elektromanyetik Ölçümlerinde Kullanılan Radyofrekans Yansıtmasız Kutu Tasarım ve Uygulaması

Anahtar Kelimeler Elektromanyetik Kalkanlama Etkinliği, Yansıtmasız Oda, Yüksek Frekans Benzetim Özet: Elektromanyetik devre, anten parametreleri, elektromanyetik kalkanlama etkinliği (ETKE), elektromanyetik uyumluluk (EMU) ve elektromanyetik girişim (EMG) gibi birçok ölçümün sağlıklı ve güvenilir bir şekilde yapılması, ölçüm ve test yapılan ortamın istenmeyen elektromanyetik girişim ve sinyallerden arındırılması ile mümkün olmaktadır. Bu nedenle bahsedilen testler ve ölçümler akredite laboratuvarlarda oldukça büyük ve yapılması maliyetli olan elektromanyetik yansıtmasız odalarda ve yüksek bedellerle yapılmaktadır. Üniversiteler, araştırma kurumları ve üretim yapan küçük ölçekli işletmelerde bu tür ölçümlerin prototipleme ve üretim aşamasında birçok kez yapılmak zorunda olunması hem zaman kaybına neden olmakta hem de üretim maliyetlerini artırmaktadır. Bu çalışmada 700-3000 MHz bandında elektromanyetik test ve ölçümlerinde kullanılabilecek küçük boyutlu ve düşük maliyetli bir yansıtmasız kutu tasarımı anlatılmış, yapılan odanın performansı değerlendirilmiştir.

An RF anechoic box system development for shielding effectiveness measurements

Shielding effectiveness is a term that defines the electromagnetic shielding property of a material. The demand of using wireless technologies and higher frequencies in new devices also bring the need to shield the unwanted electromagnetic fields. Therefore determining the shielding effectiveness of materials becomes an important concept. In this study a compact, low-cost RF anechoic box system for shielding effectiveness is explained. The design and construction of the anechoic box is given as well as the designed printed log-periodic antennas specifically for the measurement system that operates in the frequency band of 750-3000 MHz. The simulation and measurement results of the antennas given. Also, the performance of the whole system is investigated by measuring the shielding effectiveness of an absorber used in the anechoic box with another reference antenna. Open area measurements are compared to the measurements taken in the anechoic box.

Measurement of human walking on sagittal plane for exoskeleton walking pattern generation

Researchers have been worked on exoskeletons and active orthoses since 1960s. There are many competitions on these searches area. One of them is Human Exoskeleton Assistance System Prototype (HEASP) that is developed at Dokuz Eylül University. HEASPs goal is to assist one leg extremity persons. In this paper, the capturing of human walking parameters on sagittal plane is introduced. These parameters used for walking pattern generation and making pattern decision control strategies on HEASP.

Three dimensional interactive virtual anatomy laboratory design and its application

Three dimensional modeling and simulation software are becoming more widespread in medical applications. Enabling the user to view the 3D models of biological tissues and materials, to interact with the models with the ability to observe the reaction of the models to different force loading conditions in a virtual environment are the main properties of these kind of software. In addition to these properties, the graphical user interface enables the user to easily interact with the software and access its properties. These software specifications present an opportunity to understand the physical and mathematical reasons of dynamical processes in addition to presenting a visual learning environment to the researchers in health sciences. Considering above and the expectations of Dokuz Eylül University Faculty of Medicine, the development of a software that will allow the user to view and to interact with the anatomical models in addition to observing the responses of the models under different force loading conditions and material properties in real time, and hardware platform development has been aimed.

Unsupervised Segmentation of MRI using Independent Component Analysis

In this study, an autonomous classification and segmentation algorithm to diagnose and trace multiple sclerosis (MS), from magnetic resonance (MR) imaging is developed. In this method, new image stacks are derived by using three different weighted MR images, and then, independent components are obtained from those images derived. A decision maker is developed in order to choose the most suitable independent component by using spatial tone and MRI tissue properties.