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Visual line tracking with vector field guidance for UAV

Köksal, Kerem | Surucu, Dilek | Surucu, Murat | Hacıoğlu, Rıfat

Proceedings | 2014 | 2014 22ND SIGNAL PROCESSING AND COMMUNICATIONS APPLICATIONS CONFERENCE (SIU) , pp.646 - 649

In this study, it is aimed to follow a visual route by an Unmanned Aerial Vehicle (UAV). The recognition of the predetermined line by using image processing algorithms and the process of following the route by using the method of Tangent Vector Field Guidance (TVFG) have been performed in indoor and outdoor experiments. UAV's following the correct route has been ensured by calculating the deflection caused by some factors such as wind and light which adversely affect the flight of UAV. In Vector Field Guidance method, the direction angles calculated by using the vector fields that will follow the line-shaped guide path are used. Whe . . .n the path to be followed has more than one direction instead of a single straight line, it is divided into sections which consist of straight lines, and by prioritizing these lines, the most dominant line is followed. In this study, it is aimed to provide a dynamic model by considering the tracking errors. As a result of the process adopted, UAV's autonomous flight is achieved by using the visual inputs and TVFG method, and the external disturbing factors are investigated Daha fazlası Daha az

Astrositlerin noron dmamiklenne etkileri fifects of astrocytes on neuronal dynamics

Erkan, Yasemin | Özer, Mahmut | Yılmaz, Ergin

Proceedings | 2017 | 2017 MEDICAL TECHNOLOGIES NATIONAL CONGRESS (TIPTEKNO) , pp.646 - 649

Astrocytes are star-shaped glia cells and the most common cell type in the human brain with neurons. Astrocytes fulfill many functions in human brain. Providing support to the cells of the blood-brain barrier, balancing the extracellular ion concentration, supplying nutrients to the nerve tissue, and controlling the development of nerve cells are some of these tasks. In this study, the effects of calcium (Ca') ion concentration oscillations occuring in astrocytes on the neuron firing dynamics are investigated. When the obtained results are examined, it is observed that the production rate of insole 1,4,5-triphosphate (IP3), which is . . . an agent that triggers calcium release from the resoruces in astrocytes, and the degradation time of that within the cell are important effects on the spike production dynamics of the neuron in contact with astrocyte. It is determined that neurons without any stimulation continue to produce spikes through calcium oscillations in the astrocytes, at high IP3 production rates and longer IP3 degradation times Daha fazlası Daha az

Epilepsy diagnosis using probability density functions of EEG signals

Orhan, Umut | Hekim, Mahmut | Özer, Mahmut | Provaznik, Ivo

Proceedings | 2011 | INISTA 2011 - 2011 International Symposium on INnovations in Intelligent SysTems and Applications , pp.626 - 630

In this paper, the equal frequency discretization (EFD) based probability density approach was proposed to be used in the diagnosis of epilepsy from electroencephalogram (EEG) signals. For this aim, EEG signals were decomposed by using the discrete wavelet discretization (DWT) method into subbands, the coefficients in each subband were discretized to several intervals by EFD method, and the probability density of each subband of each EEG segment was computed according to the number of coefficients in discrete intervals. Then, two probability density functions were defined by means of the curve fitting over the probability densities . . .of the sets of both healthy subjects and epilepsy patients. EEG signals were classified by applying the mean square error (MSE) criterion to these functions. The result of the classification was evaluated by using the ROC analysis, which indicated 82.50% success in the diagnosis of epilepsy. As a result, the EFD based probability density approach may be considered as an alternative way to diagnose epilepsy disease on EEG signals. © 2011 IEEE Daha fazlası Daha az

Impact of hybrid autapse on firing regularity in a Hodgkin-Huxley neuron

Yılmaz, Ergin | Baysal, Veli | Özer, Mahmut

Proceedings | 2016 | 2016 24th Signal Processing and Communication Application Conference, SIU 2016 - Proceedings , pp.2233 - 2236

In this paper, the effects of autapse (a kind of synapse formed between the axon or soma of a neuron and its own dendrites) on the firing regularity and the firing rate in single Hodgkin-Huxley neuron are investigated. We consider that Hodgkin-Huxley neuron has two autapses. It is supposed that one of them is electrical synapse and the other is chemical synapse. Obtained results indicate that autapse with proper parameter values (delay time and autaptic conductance) prominently increases the firing regularity and the firing rate of a Hodgkin-Huxley neuron. © 2016 IEEE.

Change in response time of neuronal populations with noise, synaptical interactions and stimulus frequency

Özsoy, Muhammet Ali | Uzuntarla, Muhammet | Özer, Mahmut

Proceedings | 2007 | 2007 IEEE 15TH SIGNAL PROCESSING AND COMMUNICATIONS APPLICATIONS, VOLS 1-3 , pp.2233 - 2236

Neurons which are the fundamental elements of the nervous system, encode the information about stimulus they received from the external world by sensory system into action potential (spike) sequences before transmitting to the brain. In this study, a neuron population is modeled in mathematical manner and then first spike appearance time in a spike train is examined against changes in the characteristics of the periodic forcing. We also examine the effect of noise which stems from the biophysical structure of neurons and the effect of synaptic coupling which is the consequence of synaptic interaction of neurons with each other in th . . .e population to the appearance time of first spikes. The obtained results show that the mean response time of the population decreases with the increasing frequency. When the intensity of inherent noise in the neuronal environment increased, it shows a decreasing effect on the mean response only for low frequency range of the stimulus. Although the synaptic interaction coefficient does not affect substantially the mean response time of the population, it was shown that it is the fundamental parameter controlling the standard deviation of the response time Daha fazlası Daha az

Relaxation phenomena in the activation and inactivation gates of ionic channels

Özer, Mahmut

Proceedings | 2003 | Chinese Journal of Physics41 ( 2 ) , pp.206 - 218

The dynamics of a voltage-gated ionic channel is modeled by the conventional Hodgkin-Huxley mathematical formalism. In that formalism, the dynamics of the ionic channel activation and inactivation gates is modeled by a first-order differential equation dependent on the gate variable and the membrane potential. In this study a method, which combines statistical equilibrium theory and the thermodynamics of irreversible processes, is proposed for the study of the relaxation phenomena in the activation and inactivation gates of ionic channels present in the excitable membranes of neurons. In order to study the relaxation phenomena, the . . .assumption is made that the activation and inactivation gate order parameters can be treated as fluxes and forces, in the sense of Onsager's theory of irreversible thermodynamics. The kinetic equations are solved by using the Runge-Kutta method, in order to study the relaxation of the order parameters. It is found that the kinetic equations are characterized by two relaxation times. The kinetic coefficients that relate the fluxes to the forces are determined. Furthermore, it is shown that the obtained relaxation times have the same results as those obtained by using the Hodgkin-Huxley model. These results therefore indicate the validity of the proposed approach Daha fazlası Daha az

Design and implementation of a domestic solar-wind hybrid energy system

Fesli, Uğur | Bayır, Raif | Özer, Mahmut

Proceedings | 2009 | ELECO 2009 - 6th International Conference on Electrical and Electronics Engineering , pp.206 - 218

In parallel to developing technology, demand for more energy makes us seek new energy sources. The most important application field of this search is renewable energy resources. Wind and solar energy have being popular ones owing to abundant, ease of availability and convertibility to the electric energy. This work covers realization of a hybrid renewable energy system for a domestic application, which runs under a microcontroller to utilize the solar and wind power. This project is implemented in accordance with available lineelectricity. Batteries in the system are charged by either wind power via a small alternator or solar power . . . via an MPPT Module. System control relies mainly on microcontroller. Power resources and loads in the system are monitored and controlled In real time Daha fazlası Daha az

Propagation of firing rate in a feedforward network with stochastic Hodgkin-Huxley neurons

Uzuntarla, Muhammet | Özer, Mahmut | Köklükaya, Etem

Proceedings | 2010 | ANALYSIS OF BIOMEDICAL SIGNALS AND IMAGES , pp.122 - 128

We study firing rate propagation in a feedforward network with multiple layers. Neurons in the network are modeled by using stochastic Hodgkin-Huxley neuronal model, which considers stochastic behaviour of voltage-gated ion channels embedded in neuronal membranes. In the model, ion channel noise due to its stochastic behaviour is related to the cell size in such a way that the noise strength increases with decreasing the cell size, mimicking the actual biophysical conditions. An external additive current noise is also injected into the first layer of the network. Therefore, neurons in the first layer are subject to both internal and . . . external noise while neurons in the subsequent layers are subject to only internal noise. It is shown that the efficient transmission of firing rates requires an appropriate intrinsic noise level in the network if the input firing rate or the external noise strength is higher than a critical value Daha fazlası Daha az

Effects of synaptic time delay on vibrational resonance in neuronal networks

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

Proceedings | 2017 | 2017 25th Signal Processing and Communications Applications Conference, SIU 2017 , pp.122 - 128

In the phenomenon of vibrational resonance, the excitable system is under the influence of two periodic forces: a low-frequency (signal), a high-frequency (carrier). In this study, the effects of synaptic time delay on the vibrational resonance were investigated in two coupled FitzHugh-Nagumo neurons with electrical or chemical coupling. It is seen that, for both types of coupling by appropriate choice of synaptic time delay can be had a curative effect to transmission between two neurons at certain values of synaptic conductivity. © 2017 IEEE.

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

Simulation of Parkinsonian Globus Pallidus Nuclei with various network motifs

Çalım, Ali | Özer, Mahmut | Uzuntarla, Muhammet

Proceedings | 2017 | 2017 Medical Technologies National Conference, TIPTEKNO 20172017-January , pp.1 - 4

Parkinson's disease is a neurodegenerative disorder that affect human life quite negatively with motor, cognitive and psychiatric way. Recent electrophysiological experiments have shown that Basal Ganglia, spaced in the midbrain, can lead to Parkinsonism. Beta frequency oscillations and irregular burstings are most important symptoms of Parkinson's disease. They appear in Globus Pallidus and Subtalamus nuclei during the disease. In this study, anatomical connection features that may give rise to emergence of burstings are investigated, simulating Globus Pallidus and Subtalamus nuclei numerically. © 2017 IEEE.

A computer software for an efficient finger-tapping test

Özer, Mahmut | Özdemir, Taner | Gümüş, Mustafa

Proceedings | 2008 | ANALYSIS OF BIOMEDICAL SIGNALS AND IMAGES , pp.171 - 173

Quantitative description of finger-tapping movements provides more insight into the disturbances in execution of normal motor rhythm, which might be associated with brain damage. Therefore, development of finger-tapping test devices and software is of great importance. In this study, we introduce new computer software to apply a finger-tapping test through a computer keyboard. Free and preconditioned finger-tapping tests can be carried out, and test results can be analyzed within the software and saved in the software database. The test results can also be exported on any spreadsheet platform for an advanced data analysis.

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