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Manisa, Turkey

Karakuzu R.,Dokuz Eylul University | Demirgoren O.,Vestel Electronics | Icten B.M.,Dokuz Eylul University | Deniz M.E.,Dokuz Eylul University
Materials and Design | Year: 2010

This paper presents the effect of hole positions on the failure behavior of glass-epoxy laminated composite plates fabricated from stacking sequence [0/90/±45]S subjected to a traction force by three-pins. Three different hole distance parameters, namely the ratio of free edge distance to the outer holes/pin diameter (E/D = 1, 2, 3, 4, 5), the ratio of longitudinal distance between the holes/pin diameter (F/D = 2, 4, 6) and the ratio of transverse distance between the parallel holes/pin diameter (G/D = 3, 4, 5) were used to investigate the effects of hole positions on failure load and failure mode. Shear out failure mode which is not the desired mode for a structure occurs around the first and second pin holes very close to the free edge of the specimen (E/D = 1). The other specimens were damaged in bearing mode which is the most desired mode. © 2009 Elsevier Ltd. All rights reserved. Source

Gebizli C.S.,Vestel Electronics | Sozer H.,Ozyegin University
Proceedings - IEEE 38th Annual International Computers, Software and Applications Conference Workshops, COMPSACW 2014 | Year: 2014

Model-based testing facilitates automatic generation of test cases by means of models of the system under test. Correctness and completeness of these models determine the effectiveness of the generated test cases. Critical faults can be missed due to omissions in the models, which are primarily created manually. In practice, these faults are usually detected with exploratory testing performed manually by experienced test engineers. In this paper, we propose an approach for refining system models based on the experience and domain knowledge of these test engineers. Our toolset analyzes the execution traces that are recorded during exploratory testing activities and identifies the omissions in system models. The identified omissions guide the refinement of models to be able to generate more effective test cases. We applied our approach in the context of an industrial case study to improve the models for model-based testing of a Digital TV system. After applying our approach, three critical faults were detected. These faults were not detected by the initial set of test cases and they were also missed during the exploratory testing activities. © 2014 IEEE. Source

Gezer C.,Vestel Electronics
2014 22nd Signal Processing and Communications Applications Conference, SIU 2014 - Proceedings | Year: 2014

In this study we are exploiting the periodic nature of human activities in order to better utilize the channel between the on body sensors and a sink that collects the data coming from those sensors. We propose a health-care monitoring system where nodes having good quality links use the channel and the ones with poor quality links defer their packet transmissions until better link conditions. In such an adaptive way, the allocated bandwidth for the nodes with good quality links is also improved. We use the periodic beacons send by the IEEE 802.15.4 coordinator (sink) for the link quality estimation. Besides, we define a two-level prioritization scheme compatible with IEEE 802.15.4, for different application requirements. © 2014 IEEE. Source

Tulu M.E.,Vestel Electronics | Yildirim D.,Technical University of Istanbul
12th International Conference on Environment and Electrical Engineering, EEEIC 2013 | Year: 2013

The principle of induction cooker is based on heating the metallic pan with circulating eddy currents induced by high frequency AC magnetic field. The coil within the induction cooker and the load (pan / pot) acts as a transformer if the load has an electrically conducting base. If the conducting base is ferromagnetic, then the power is transferred with high efficiency. In this document, the quasi resonant topology for induction heating is analyzed. Moreover, pan detection and the method to determine the amount of power delivered to the pan is covered. Jitter method and the three basic benefits of using jitter method during switching action is pointed out. An experimental prototype with a power rating of 2300W is constructed to test the validity of the proposed methods and control algorithms. It was observed that the quasi resonant topology is advantageous over half bridge topology when jitter method is used to drive the semiconductor switches. The test results of the prototype reveal that the current harmonics drawn from the utility is within the limits of the standard EN 61000-3-2. © 2013 IEEE. Source

Yuksel U.,Vestel Electronics | Yuksel U.,Ozyegin University | Sozer H.,Ozyegin University
IEEE International Conference on Software Maintenance, ICSM | Year: 2013

Static code analysis tools automatically generate alerts for potential software faults that can lead to failures. However, developers are usually exposed to a large number of alerts. Moreover, some of these alerts are subject to false positives and there is a lack of resources to inspect all the alerts manually. To address this problem, numerous approaches have been proposed for automatically ranking or classifying the alerts based on their likelihood of reporting a critical fault. One of the promising approaches is the application of machine learning techniques to classify alerts based on a set of artifact characteristics. In this work, we evaluate this approach in the context of an industrial case study to classify the alerts generated for a digital TV software. First, we created a benchmark based on this code base by manually analyzing thousands of alerts. Then, we evaluated 34 machine learning algorithms using 10 different artifact characteristics and identified characteristics that have a significant impact. We obtained promising results with respect to the precision of classification. © 2013 IEEE. Source

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