Time filter

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Cetin N.O.,Orta Dogu Teknik University | Hava A.M.,Orta Dogu Teknik University
2010 National Conference on Electrical, Electronics and Computer Engineering, ELECO 2010 | Year: 2010

High frequency common mode voltage (CMV) in voltage source inverter driven AC motors results in parasitic common mode current (CMC) in the motor. In this paper, the cause and the undesired effects of the CMV/CMC are reviewed, the improvements of the passive suppression techniques, the common mode inductor (CMI) and the pure sine filter (PSF), are progressively studied and their experimental performance is investigated in a 4kW motor drive. It is experimentally shown that employing the CMI reduces the CMC effectively, and employing the PSF eliminates all the negative effects caused at the motor side by the high frequency switching.

Demir O.T.,Orta Dogu Teknik University | Tuncer T.E.,Orta Dogu Teknik University
2014 22nd Signal Processing and Communications Applications Conference, SIU 2014 - Proceedings | Year: 2014

Optimization problem of broadcast beamforming is nonconvex due to rank condition. Semidefinite relaxation (SDR) method is proposed to solve this problem. However, in certain cases, the performance of SDR becomes unacceptable. In this paper, an equivalent formulation of the original problem without rank condition is found. An iterative algorithm which is shown to converge to a rank one solution is presented. Experimental results show that the proposed algorithm is very effective and gives better results than other existing approaches. © 2014 IEEE.

Eyili M.,ASELSAN A.S | Demirekler M.,Orta Dogu Teknik University
2014 22nd Signal Processing and Communications Applications Conference, SIU 2014 - Proceedings | Year: 2014

In this paper, two proposed Track Before Detect (TBD) algorithms for spawning targets on the basis of raw radar measurements are described. These algorithms are developed by using multi-model particle filter method. To improve the efficiency of particle filter a novel reduced order model is introduced. The algorithms are confirmed by using the simulation results and their performances are analyzed on the basis of the probability of target existence and Root Mean Square (RMS) estimation accuracy for very low Signal-to-Noise Ratio (SNR) targets. © 2014 IEEE.

Hacihabiboglu H.,Orta Dogu Teknik University
2014 22nd Signal Processing and Communications Applications Conference, SIU 2014 - Proceedings | Year: 2014

Open-spherical acoustic intensity probes are microphone arrays based on the Kirchhoff-Helmholtz integral and are used in the measurement of active acoustic intensity. The acoustic intensity measurements obtained by these arrays can be used to localise sound sources. Previously, the performance of these arrays in acoustic free field conditions were obtained using numerical simulations and it was shown that they provide better performance than other types of probes. This paper discusses the implementation of open spherical microphone arrays and their performance in reverberant enclosures. © 2014 IEEE.

Gunel B.,Orta Dogu Teknik University
2014 22nd Signal Processing and Communications Applications Conference, SIU 2014 - Proceedings | Year: 2014

An audio recording, made in a real environment, carries an acoustical signature which changes according to the acoustical characteristics of the environment and the recording positions. This signature which is similar to a 3D room impulse response contains the directions, levels and arrival times of the direct source and reflections. Although it is easy to obtain reverberant recordings by convolving clean recordings with the acoustical signature, estimating the signature from any recording is a difficult inverse problem. Acoustical signature estimation is important in acoustical analysis, audio forensics for authentication, room size and shape estimation and improving speech intelligibility by dereverberation. In this work, the statistical modelling of intensity vector directions, which are obtained from compact microphone array recordings is made. Obtained statistical distribution is used for reducing the reverberation based on the maximum-likelihood estimation method. This dereverberated sound enables deconvolving the reverberant recordings to estimate the acoustical signature. © 2014 IEEE.

Tengilimoglu B.,ASELSAN A.S | Bazlamacci C.F.,Orta Dogu Teknik University
2014 22nd Signal Processing and Communications Applications Conference, SIU 2014 - Proceedings | Year: 2014

The concept of partial reconfiguration has been introduced by leading FPGA vendors in recent years. Partial reconfiguration is a technique that allows to reprogram/reconfigure a specific part of an FPGA during runtime. This method allows switching between design modules that are not necessary to function at the same time without interrupting the FPGA's processing of the current task. Hence larger designs can be implemented on the same FPGA. This work is an implementation of partial reconfiguration on an FPGA which is used as a hardware accelarator in a real-time target detection and tracking system. Run-time switching between different algorithm components became possible without interrupting the target detection and tracking capability of the overall system by using partial reconfiguration in the system. By this approach, FPGA resources are used efficiently and power consumption is reduced. © 2014 IEEE.

Alkan S.,Oita University | Yarman-Vural F.T.,Orta Dogu Teknik University
2014 22nd Signal Processing and Communications Applications Conference, SIU 2014 - Proceedings | Year: 2014

In this study, we provide a methodology to localize the brain regions that contribute to semantic category classification. For this purpose we first cluster the data using spectral clustering. Then we extract local features within each cluster by using mesh-arc descriptors. Finally, we test the classification accuracy of each cluster against a hypothesis testing measure we provide here. We have found that, for the experimental task at hand, calcerine fissure and angular gyrus were most effective in classification. These results are shown to be match well with the nature of the experiment. Thus the validity of our approach is confirmed. © 2014 IEEE.

Sabuncu M.,Radar | Demirekler M.,Orta Dogu Teknik University
2011 IEEE 19th Signal Processing and Communications Applications Conference, SIU 2011 | Year: 2011

In this study IMM-PF (Interacting Multiple Model - Particle Filter) algorithm has been developed in order to achieve increased performance for tracking maneuvering targets. Track lost rate and gate sizes are determined as the performance criteria. The developed algorithm has been compared with standart IMM algorithm. Effects of the number of particles on the performance is analysed. © 2011 IEEE.

Yilmaz T.,Pennsylvania State University | Caner A.,Orta Dogu Teknik University
Bridge Structures | Year: 2012

Displacement capacity verification analysis is usually used to evaluate the level of displacement at which structural elements reach their inelastic deformation capacities. In engineering practice, a modified version of displacement capacity analysis is used in the seismic performance assessment of bridge structures as an alternative to ductility and drift based approaches. In this seismic performance evaluation for a given target damage level, top bent displacement demand should not exceed a certain fraction of displacement capacity under safety evaluation earthquake level. A limited amount of study is available in the literature addressing the limiting values used in setting target damage levels. Furthermore, prediction of seismic response of structures over flexible foundations is not an easy task due to the complexities involved in the soil-structure interaction. The focus of this study is to investigate target damage levels by defining a relationship between displacement capacity to demand ratio and strain based damage levels for seismic performance assessment of two column reinforced concrete bridge bents over flexible foundations. © 2012 - IOS Press and the authors. All rights reserved.

Yigit A.,Orta Dogu Teknik University | Temizel A.,Orta Dogu Teknik University
SIU 2010 - IEEE 18th Signal Processing and Communications Applications Conference | Year: 2010

Packages that are left unattended in public spaces are a security concern and timely detection of these packages is important for prevention of potential threats. However continuous surveillance of such places is difficult. Therefore, it is important to aid operators with automatic detection of abandoned items. Most of the methods define abandoned items as items newly added to the scene and stayed stationary for a predefined time. Hence other stationary objects, such as people sitting on a bench, are also detected as suspicious objects resulting in a high number of false alarms. These false alarms could be prevented by discriminating suspicious items as living/nonliving objects. In this paper, a system using a thermal camera in addition to a visible band camera is proposed. By analysis of information from different cameras, people and the objects left behind can be detected separately to reduce the false alarm rate. ©2010 IEEE.

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