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Comparision of classifier performances in diagnosing congestive heart failure using heart rate variability

Narin, Ali | Özer, Mahmut | İşler, Yalçın


In this study, the performance of different discrimination algorithms in the analysis of heart rate variability that are used in discriminating the patients with congestive heart failure from normal subjects were investigated. Classifier algorithms of linear discriminant analysis, k-nearest neighbors, multilayer perceptron, radial basis functions and support vector machines were examined with different parameter values. As a result, the maximum classification accuracy of 91.56% was achieved by using multilayer perceptron with 11 neurons in hidden layer.

Teleconferencing acoustic echo cancellation using adaptive Hammerstein block structure

Özdinç, Tuğba Özge | Hacıoğlu, Rıfat


Acoustic echo in voice transmission systems severely degrades the speech quality and the speech intelligibility of speech signal due to it is formed through picking up sounds from the loudspeaker by speaker microphone. The dynamic strucure of the acoustic echo system contains cascade connection of an electro-acoustic static nonlinear system and a dynamic linear system. Hence linear models can not be successful solution to echo problem. In this paper, acoustic echo problem is mentioned and an algorithm that adapts the parameters of nonlinear Hammerstein system (cascade connection of a static nonlinearity and a dynamic linear system) . . .is suggested Daha fazlası Daha az

Simultaneous localization and mapping of mines with unmanned aerial vehicle [Insansiz Hava Araci ile Maden Ocaginin Es Zamanli Konum Belirleme ve Haritalandirilmasi]

Altan, Aytaç | Bayraktar, Köksal | Hacıoğlu, Rıfat

Proceedings | 2016 | 2016 24th Signal Processing and Communication Application Conference, SIU 2016 - Proceedings , pp.1433 - 1436

In this stuidy, the position information from ultrasound sensors on UAV related to floor gallery mine passed through the filter, it is aimed to control the position of simultaneously creating the optimum environmental map. The simultaneous in galleries made mapping, mine the data of air to the designated central monitoring system with real-time location information is transmitted to the ventilation system, which is intended to more effectively work in the mines. The gallery maps which simultaneous location and mapping information obtained by UAV Extended Kalman Filter algorithms processed were obtained experimentally. © 2016 IEEE.

The internationalization of higher education in Turkey: Realities, motivations and opportunities

Özer, Mahmut

Note | 2016 | Insight Turkey18 ( 4 ) , pp.53 - 63

The internationalization of higher education constitutes one of the essential components that countries pursue. As economic growth and qualified higher education are directly related, many countries in the global competitive environment are re-evaluating their higher education systems. After a brief examination of the situation in the world, this commentary focuses specifically in the Turkish case. It argues that Turkey has taken strategic steps in recent years to strengthen the internationalization of its higher education system. In this regard, the paper will deal with the main challenges and future possibilities for the Turkish e . . .ducation system. © 2016, SETA. All rights reserved Daha fazlası Daha az

Effect of sub-threshold stimuli on neuronal dynamics

Ekmekçi N. Hakan | Özer, Mahmut

Proceedings | 2005 | Proceedings of the IEEE 13th Signal Processing and Communications Applications Conference, SIU 20052005 , pp.143 - 146

Voltage-gated ion channels are of great importance in the generation and propagation of electrical signals in the excitable membranes. In this study, we introduce the stochastic version of the Hodgkin-Huxley formalism and investigate the effect of channel noise on neuronal dynamic behaviors based on a model with the Gaussian noise. We show that the channel noise may result in a spiking activity for subthreshold stimulus, and that the firing dynamics follows more regular patterns when the membrane patch becomes smaller. It is also shown that the stochastic model converges to the deterministic model for very large membrane patches and . . . the neurons can encode subthreshold stimuli by considering the channel noise. © 2005 IEEE Daha fazlası Daha az

Effect of the sub-threshold periodic current forcing on the regularity and the synchronization of neuronal spiking activity

Özer, Mahmut | Uzuntarla, Muhammet | Ağaoğlu, Şükrüye Nihal

Article | 2006 | Physics Letters, Section A: General, Atomic and Solid State Physics360 ( 1 ) , pp.135 - 140

We first investigate the amplitude effect of the subthreshold periodic forcing on the regularity of the spiking events by using the coefficient of variation of interspike intervals. We show that the resonance effect in the coefficient of variation, which is dependent on the driving frequency for larger membrane patch sizes, disappears when the amplitude of the subthreshold forcing is decreased. Then, we demonstrate that the timings of the spiking events of a noisy and periodically driven neuron concentrate on a specific phase of the stimulus. We also show that increasing the intensity of the noise causes the phase probability densit . . .y of the spiking events to get smaller values, and eliminates differences in the phase locking behavior of the neuron for different patch sizes. © 2006 Elsevier B.V. All rights reserved Daha fazlası Daha az

Collective temporal coherence for subthreshold signal encoding on a stochastic small-world Hodgkin-Huxley neuronal network

Özer, Mahmut | Uzuntarla, Muhammet | Kayıkcıoğlu, Temel | Graham, Lyle J.

Article | 2008 | Physics Letters, Section A: General, Atomic and Solid State Physics372 ( 43 ) , pp.6498 - 6503

We study the collective temporal coherence of a small-world network of coupled stochastic Hodgkin-Huxley neurons. Previous reports have shown that network coherence in response to a subthreshold periodic stimulus, thus subthreshold signal encoding, is maximal for a specific range of the fraction of randomly added shortcuts relative to all possible shortcuts, p, added to an initially locally connected network. We investigated this behavior further as a function of channel noise, stimulus frequency and coupling strength. We show that temporal coherence peaks when the frequency of the external stimulus matches that of the intrinsic sub . . .threshold oscillations. We also find that large values of the channel noise, corresponding to small cell sizes, increases coherence for optimal values of the stimulus frequency and the topology parameter p. For smaller values of the channel noise, thus larger cell sizes, network coherence becomes insensitive to these parameters. Finally, the degree of coupling between neurons in the network modulates the sensitivity of coherence to topology, such that for stronger coupling the peak coherence is achieved with fewer added short cuts. © 2008 Elsevier B.V. All rights reserved Daha fazlası Daha az

The controller of the camera used in target tracking for unmanned vehicle with model predictive controller

Altan, Aytaç | Hacıoğlu, Rıfat


In this study, unmanned vehicles used for target tracking camera RRP (revolute revolute prismatic) joint structure with a three-jointed robot arm with the position, velocity and acceleration control is made. In order to be able to follow the specified trajectory, the system used in the control of the robot arm with joint structure RRP target tracking model based on changing according to the structure proposed by the MPC is implemented. Also the PID (Proportional Integral Dervative) is provided with control comparison was made. MATLAB/Simulink simulations performed unmanned vehicles used for target tracking in robotic camera control . . .with the system were investigated in the MPC Daha fazlası Daha az

Dynamical structure underlying inverse stochastic resonance and its implications

Uzuntarla, Muhammet | Cressman John R. | Özer, Mahmut | Barreto, Erenest

Article | 2013 | Physical Review E - Statistical, Nonlinear, and Soft Matter Physics88 ( 4 ) , pp.1686 - 1689

We investigate inverse stochastic resonance (ISR), a recently reported phenomenon in which the spiking activity of a Hodgkin-Huxley model neuron subject to external noise exhibits a pronounced minimum as the noise intensity increases. We clarify the mechanism that underlies ISR and show that its most surprising features are a consequence of the dynamical structure of the model. Furthermore, we show that the ISR effect depends strongly on the procedures used to measure it. Our results are important for the experimentalist who seeks to observe the ISR phenomenon. © 2013 American Physical Society.

Impact of network activity on noise delayed spiking for a Hodgkin-Huxley model

Özer, Mahmut | Graham, Lyle J.

Article | 2008 | European Physical Journal B61 ( 4 ) , pp.499 - 503

A new adaptive neuro-fuzzy solution for optimization of the parameters in the digital holography setup

Ustabaş, Kaya Gülhan | Erkaymaz, Okan | Saraç, Zehra

Article | 2019 | Soft Computing23 ( 18 ) , pp.8827 - 8837

In this paper,a fuzzy interference and an adaptive neuro-fuzzy interference system models have been presented in order to accelerate designing of the digital holographic setup without experiment. The setting parameters of experimental holographic setup, which affect the quality of images obtained from reconstructed holograms, are predicted digitally by proposed models before the recording process. Hence, we reduce the required time for designing of digital holographic setup with optimization process. The adaptive neuro-fuzzy interference system model for the optimization of the digital holographic setup is first attempt in the liter . . .ature. The accuracy of the proposed models is examined by comparing the presented models and actual calculated experimental root-mean-square values. As a result, the accuracy of the adaptive neuro-fuzzy interference system shows the better performance than the fuzzy interference system. Moreover, the design of experimental setup can be occurred numerically in a short time by using adaptive neuro-fuzzy interference system models. © 2018, Springer-Verlag GmbH Germany, part of Springer Nature Daha fazlası Daha az

Analysis of time-course of the recovery from inactivation for the molluscan ionic currents

Özer, Mahmut

Article | 2004 | Iranian Journal of Science and Technology, Transaction B: Engineering28 ( 3 B ) , pp.351 - 358

In this study, the time-course of the recovery from inactivation of molluscan ionic currents is examined. Molluscan voltage-gated ionic currents are described in Hodgkin-Huxley-like equations. The peak value function of the recovering conductance is derived from the mathematical equivalent of an experimental procedure of the recovery process in a general form by including the number of inactivation gates. Then the curves of the recovery and its approximation for the molluscan ionic currents are obtained. It is shown that recovering conductance of molluscan ionic currents is asymptotically exponential. © Shiraz University.

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