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Türkiye’de uluslararası öğrenciler

Özer, Mahmut

Article | 2012 | Yükseköğretim ve Bilim Dergisi2 ( 1 ) , pp.10 - 13

Son yıllarda dünya genelinde sayıları üç milyonun üzerinde olan uluslararası öğrencileri kendi ülkelerinin yükseköğretim kurumlarına alabilmek için ülkeler kıyasıya rekabet etmektedirler. Uluslararası öğrenciler, artık yükseköğretim sistemleri ve kurumlarının uluslararasılaşma boyutlarının en önemli göstergelerinden birisini oluşturmaktadır. Bu bağlamda, yükseköğretim sistemimiz ve kurumlarımızın bu göstergesinin ne durumda olduğunun tespiti, oldukça büyük bir genişleme yaşayan yükseköğretim sistemimiz açısından büyük önem arz etmektedir. Bu çalışmada, ülkemizdeki uluslararası öğrencilerin durumu ele alınmaktadır There are over thre . . .e million international students worldwide, and in recent years higher education institutions compete with each other in order to receive these students to their institutions. International students are now one of the most important indicator of the internationalization of the higher education systems and institutions. In this context, the detection of the status of this indicator in our higher education system and institutions is of great importance as our higher education system shows a large expansion. This study, discusses the status of international students in our countr Daha fazlası Daha az

Estimation of the propagation of flexural waves in thin plates using a single low-cost sensor

Onur, Tuğba Özge | Carlson, Johan E | Svanström, Erika | Hacıoğlu, Rıfat

Article | 2019 | Iranian Journal of Science and Technology - Transactions of Electrical Engineering43 ( 3 ) , pp.405 - 413

This paper demonstrates how flexural wave propagation in a thin plate can be modeled by estimating the combined effect of the excitation source signal and the impulse response of the ultrasonic sensor. The wave propagation in the plate is modeled using the wave equation for the flexural wave mode. A theoretical model for flexural wave propagation in thin plates has been derived, and it has been compared with measurements excited by tapping gently on the surface. The combined effects of the excitation source signal and the impulse response of the low-cost piezoelectric sensor are modeled using finite-impulse response and/or infinite- . . .impulse response filters. Thereafter, the performances of the selected filters are compared on estimating the wave propagation in a thin quartz glass plate. Results indicate that the most accurate estimation of wave propagation has been obtained using a linear phase filter which attributes all dispersions to the flexural wave. © 2018, Shiraz University Daha fazlası Daha az

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

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


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

A computer software for simulating single-compartmental model of neurons

Özer, Mahmut | İşler, Yalçın | Özer, Halil

Article | 2004 | Computer Methods and Programs in Biomedicine75 ( 1 ) , pp.51 - 57

In this paper, a new computer software package, Yalzer, is introduced for simulating single-compartmental model of neurons. Passive or excitable membranes with voltage-gated ion channels can be modeled, and current clamp and voltage clamp experiments can be simulated. In the Yalzer, first-order differential equations used to define the dynamics of the gate variables and the membrane potential are solved by two separate integration methods with variable time steps: forward Euler and exponential Euler methods. Outputs of the simulation are shown on a spreadsheet template for allowing flexible data manipulation and can be graphically d . . .isplayed. The user can define the model in detail, and examine the excitability of the model and the dynamics of voltage-gated ion channels. The software package addresses to ones who want to run simple simulations of neurons without need to any programming language skills or expensive software. It can also be used for educational purposes. © 2003 Elsevier Ireland Ltd. All rights reserved Daha fazlası Daha az

Activation kinetics of T-type calcium channel by a path probability approximation

Özer, Mahmut

Article | 2004 | NeuroReport15 ( 9 ) , pp.1451 - 1455

We previously formulated dynamics of ion channel gates by the path probability method. In this study, we apply that theoretical approach to derive the activation rate kinetics of T-type calcium channel in thalamic relay neurons. We derive explicit expressions of the forward and backward rate constants and show that the proposed rate constants accurately capture form of the empirical time constant, and that they also provide its saturation to a constant value at depolarized membrane potentials. We also compare our derivations with linear and nonlinear thermodynamic models of rate kinetics obtained from the same calcium channel, and s . . .how that it is possible to capture saturation of the time constant for the depolarized membrane potentials by the only proposed rate constants. © 2004 Lippincott Williams & Wilkins Daha fazlası Daha az

Visual line tracking with vector field guidance for UAV

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


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

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.

Real time detection of alternator failures using intelligent control systems

Uçar, Murat | Bayır, Raif | Özer, Mahmut

Proceedings | 2009 | ELECO 2009 - 6th International Conference on Electrical and Electronics Engineering , pp.646 - 649

On todays vehicles, dynamos are being left gradually and alternators take the turn instead for charging systems. Alternator is an electromechanical device which converts mechanical energy into electrical energy. Superior feature of alternators is that they can be charged on idling epoch and they have more output current. On the other hand by using diodes alternative current can be converted into direct current. Alternators are the main component of the charging system on modern vehicles. In this study, alternator failures are detected using fuzzy logic and artificial neural network. These are double diode failure, excessive current, . . . excessive stretch belt, loose belt, loose brush, regulator failure, short circuits on coils, one broken connection on rotor coil, two broken connection on rotor coil, broken connection on tridiode and tridiode short circuit. For detecting the failures, current, accumulator voltage, alternator voltage and the epoch number of the alternator is measured and alternator failure detection classification is implemented by designing an intelligent system inference according to these measured values Daha fazlası Daha az

Comparison of artificial neural network and regression models to diagnose of knee disorder in different postures using surface electromyography

Uzun, Rukiye | Erkaymaz, Okan | Şenyer Yapıcı, İrem

Article | 2018 | Gazi University Journal of Science31 ( 1 ) , pp.100 - 110

The surface electromyography (sEMG) is useful tool to diagnose of knee disorder in clinical environments. It assists in designing the clinical decision support systems based classification. These systems exhibit complex structure because of sEMG data obtained at different postures at this study. In this context, we have researched the classification performance of each posture using artificial neural network (ANN) and logistic regression (LR) models and have showed that the classification success of the model used sitting posture data is higher than other postures (gait and standing). We have promoted this finding by using machine l . . .earning and statistical methods. The results show that the proposed models can classify with over 95% of success, and also the ANN model has higher performance than the LR model. Our ANN model outperforms reported studies in literature. The accuracy results indicate that the models used the only sitting posture data can exhibit successful classification for the knee disorder. Therefore, the usage of complex dataset is prevented for diagnosing knee disorder. © 2018, Gazi University Eti Mahallesi. All rights reserved Daha fazlası Daha az

Controlling the first-spike latency response of a single neuron via unreliable synaptic transmission

Uzuntarla, Muhammet | Özer, Mahmut | Guo D.Q.

Article | 2012 | European Physical Journal B85 ( 8 ) , pp.100 - 110

Previous experimental and theoretical studies suggest that first-spike latency is an efficient information carrier and may contain more amounts of neural information than those of other spikes. Therefore, the biophysical mechanisms underlying the first-spike response latency are of considerable interest. Here we present a systematical investigation on the response latency dynamics of a single Hodgkin-Huxley neuron subject to both a suprathreshold periodic forcing and background activity. In contrast to most earlier works, we consider a biophysically realistic noise model which allows us to relate the synaptic background activity to . . .unreliable synapses and latency. Our results show that first-spike latency of a neuron can be regulated via unreliable synapses. An intermediate level of successful synaptic transmission probability significantly increases both the latency and its jitter, indicating that the unreliable synaptic transmission constrains the signal detection ability of neurons. Furthermore, we demonstrate that the destructive influence of synaptic unreliability can be controlled by the input regime and by the excitatory coupling strength. Better tuning of these two factors could help the H-H neuron encode information more accurately in terms of the first-spike latency. © 2012 EDP Sciences, Società Italiana di Fisica, Springer-Verlag Daha fazlası Daha az

Stochastic resonance on Newman-Watts networks of Hodgkin-Huxley neurons with local periodic driving

Özer, Mahmut | Perc, Matjaž | Uzuntarla, Muhammet

Article | 2009 | Physics Letters, Section A: General, Atomic and Solid State Physics373 ( 10 ) , pp.964 - 968

We study the phenomenon of stochastic resonance on Newman-Watts small-world networks consisting of biophysically realistic Hodgkin-Huxley neurons with a tunable intensity of intrinsic noise via voltage-gated ion channels embedded in neuronal membranes. Importantly thereby, the subthreshold periodic driving is introduced to a single neuron of the network, thus acting as a pacemaker trying to impose its rhythm on the whole ensemble. We show that there exists an optimal intensity of intrinsic ion channel noise by which the outreach of the pacemaker extends optimally across the whole network. This stochastic resonance phenomenon can be . . .further amplified via fine-tuning of the small-world network structure, and depends significantly also on the coupling strength among neurons and the driving frequency of the pacemaker. In particular, we demonstrate that the noise-induced transmission of weak localized rhythmic activity peaks when the pacemaker frequency matches the intrinsic frequency of subthreshold oscillations. The implications of our findings for weak signal detection and information propagation across neural networks are discussed. © 2009 Elsevier B.V. All rights reserved Daha fazlası Daha az

Spike latency and jitter of neuronal membrane patches with stochastic Hodgkin-Huxley channels

Özer, Mahmut | Uzuntarla, Muhammet | Perc, Matjaž | Graham, Lyle J.

Article | 2009 | Journal of Theoretical Biology261 ( 1 ) , pp.83 - 92

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