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Full-Text Articles in Engineering

Dynamic Stability Enhancement Of A Multimachine Electric Power System Using Statcom, Hasan Fayazi Boroujeni, Reza Hemmati, Sayed Mojtaba Shirvani Boroujeni Jan 2012

Dynamic Stability Enhancement Of A Multimachine Electric Power System Using Statcom, Hasan Fayazi Boroujeni, Reza Hemmati, Sayed Mojtaba Shirvani Boroujeni

Turkish Journal of Electrical Engineering and Computer Sciences

With the expansion of electric power systems, the size and complexity of the network is increased. One of the most important drawbacks of network expansion is the reduction in the damping torque of the whole system. The lack of damping torque can lead to fluctuations and instability in the power system. With regard to this problem, power system stabilizers (PSSs) have been widely utilized to improve power system stability. However, due to some drawbacks of the conventional PSSs, the need for finding a better substitution still remains. Therefore, in this paper, the application of a static synchronous compensator (STATCOM) to …


Optimal In Vitro Realization Of Pulsatile Coronary Artery Flow Waveforms Using Closed-Loop Feedback Algorithms With Multiple Flow Control Devices, Serdar Yilmaz, Onur Toker, Nurullah Arslan, Herman Sedef Jan 2012

Optimal In Vitro Realization Of Pulsatile Coronary Artery Flow Waveforms Using Closed-Loop Feedback Algorithms With Multiple Flow Control Devices, Serdar Yilmaz, Onur Toker, Nurullah Arslan, Herman Sedef

Turkish Journal of Electrical Engineering and Computer Sciences

In this paper, we study optimal in vitro realization of pulsatile coronary artery flows using newly proposed closed-loop feedback algorithms with a clearly defined mathematical performance objective, and we compare several flow control device technologies in terms of their ability to generate pulsatile flow signals as accurately as possible. In the literature, there are several published results for in vitro pulsatile flow realization systems. However, most of the proposed systems operate in an open-loop setting and use a single flow control device, and their performance is assessed mostly by graphical means without a clearly defined mathematical performance objective. Furthermore, some …


Design, Implementation, And Performance Analysis Of The Worldfip/Atm Local Bridge, Tuncay Aydoğan, İbrahi̇m Özçeli̇k, Aki̇f Kutlu, Hüseyi̇n Eki̇z Jan 2012

Design, Implementation, And Performance Analysis Of The Worldfip/Atm Local Bridge, Tuncay Aydoğan, İbrahi̇m Özçeli̇k, Aki̇f Kutlu, Hüseyi̇n Eki̇z

Turkish Journal of Electrical Engineering and Computer Sciences

World factory instrumentation protocol (WorldFIP) is a fieldbus network protocol that provides a link between level zero (sensors/actuators) and level one (field controllers such as programmable logic controllers, etc.) in industrial automation systems. Accessing and connecting the WorldFIP remotely is important for monitoring, maintaining, and controlling devices in a factory in which asynchronous transfer mode (ATM) is used as a backbone network. In this study, a transparent WorldFIP/ATM bridge was designed and implemented in order to access devices on WorldFIP via an ATM network. This designed bridge may also provide control of the devices over wide area networks. The bridge's …


Adaptive Qos Scheduling In A Service-Oriented Grid Environment, Tan Fong Ang, Teck Chaw Ling, Keat Keong Phang Jan 2012

Adaptive Qos Scheduling In A Service-Oriented Grid Environment, Tan Fong Ang, Teck Chaw Ling, Keat Keong Phang

Turkish Journal of Electrical Engineering and Computer Sciences

The use of grid technology and web services for resource sharing has received tremendous attention in recent years. The merging of these 2 technologies is able to provide additional multiple types of services and functionalities. However, the problem of scheduling services to meet quality of service (QoS) requirements remains challenging. This paper proposes an adaptive QoS (AQoS) scheduling algorithm for service-oriented grid environments. AQoS uses benchmarking and curve-fitting based on historical records to estimate job length. Job length and users' QoS requirements are then used to make scheduling decisions. AQoS is able to maximize service availability, reliability, and resource utilization …


Fast Software Multiplication In F_2[X] For Embedded Processors, Serdar Süer Erdem Jan 2012

Fast Software Multiplication In F_2[X] For Embedded Processors, Serdar Süer Erdem

Turkish Journal of Electrical Engineering and Computer Sciences

We present a novel method for fast multiplication of polynomials over F_2 which can be implemented efficiently in embedded software. Fast polynomial multiplication methods are needed for the efficient implementation of some cryptographic and coding applications. The proposed method follows a strategy to reduce the memory accesses for input data and intermediate values during computation. This strategy speeds up the binary polynomial multiplication significantly on typical embedded processors with limited memory bandwidth. These multiplications are usually performed by the comb method or the Karatsuba-based methods in embedded software. The proposed method has speed and memory advantages over these methods on …


Reconfigurable Antenna Structure For Rfid System Applications Using Varactor-Loading Technique, Yusuf Sevi̇nç, Adnan Kaya Jan 2012

Reconfigurable Antenna Structure For Rfid System Applications Using Varactor-Loading Technique, Yusuf Sevi̇nç, Adnan Kaya

Turkish Journal of Electrical Engineering and Computer Sciences

A novel method is presented for electrically tuning the frequency of a compact radio-frequency identification (RFID) tag antenna. A tuning circuit, comprising a radio frequency (RF) switch and discrete passive components, was completely integrated into the antenna element, which is thus free of DC wires. The low-profile printed antennas were fabricated together with the layouts of the DC control circuits and other RF/baseband circuit footprints. A surface-mounted varactor was applied as a frequency-tuning element at the proper places of the meandered slots in the compact antenna. Prototype designs showed that the in-band frequency (return loss < 10 dB) was tunable from 2.4 GHz to 2.8 GHz when the bias voltage varied from 4 V to 7 V. The impact of the tuning circuit on the antenna's return loss and radiation pattern were experimentally studied through comparison with the performance of a reference antenna not incorporating the tuning circuit. The proposed frequency tuning concept can be extended to more complex compact structures as well as other types of antennas to give enhanced electrical performance.


Research On Cutoff Wavelength Of Dominant Mode And Field Patterns In Trapezoidal Microshield Lines, Hai Sun, Yujiang Wu Jan 2012

Research On Cutoff Wavelength Of Dominant Mode And Field Patterns In Trapezoidal Microshield Lines, Hai Sun, Yujiang Wu

Turkish Journal of Electrical Engineering and Computer Sciences

The influence of the position of the metallic signal strip on the cutoff characteristic of the dominant mode and the field patterns in 3 types of trapezoidal microshield lines are calculated by the edge-based finite element method. These trapezoidal microshield lines include trapezoidal microshield lines with a single signal line, dual signal lines, and 3 signal lines. The cutoff wavelength of the dominant mode can be adjusted by changing the dimensions of metallic signal strips as well as by adjusting their positions. Field patterns of the dominant mode and the first-higher-order mode for different dimensions and the dielectric constant of …


Effects Of Diacritics On Turkish Information Retrieval, Adi̇l Alpkoçak, Meltem Ceylan Jan 2012

Effects Of Diacritics On Turkish Information Retrieval, Adi̇l Alpkoçak, Meltem Ceylan

Turkish Journal of Electrical Engineering and Computer Sciences

We investigate the effects of improper use of diacritics in the Turkish alphabet on information retrieval. A diacritic is simply a supplementary sign added to a letter to change the sound value of the letter, and the Turkish alphabet has 5 special letters derived from Latin by adding different diacritics. The statistical analysis performed in this study shows that retrieval performance significantly decreases when documents and queries contain letters with different forms, such that documents consist of letters with diacritics while queries consist of standard Latin letters and vice versa. In order to tackle this challenge, we propose 3 approaches: …


Three-Dimensional Numerical Simulation Of Crystal And Crucible Rotations During Czochralski Growth Of Ge_Xsi_{1-X} Single Crystals, Serkan Abbasoğlu Jan 2012

Three-Dimensional Numerical Simulation Of Crystal And Crucible Rotations During Czochralski Growth Of Ge_Xsi_{1-X} Single Crystals, Serkan Abbasoğlu

Turkish Journal of Electrical Engineering and Computer Sciences

The influence of crystal and crucible rotations on the flow field and the radial segregation of silicon are predicted during the growth of Ge_xSi_{1-x} crystals by the Czochralski method under microgravity conditions. Time-dependent 3-dimensional numerical simulations are carried out to present the influence of several rotation rates on the radial segregation and flow fields during the growth of Ge_xSi_{1-x}. Thermal and solutal Marangoni convection are also considered during this study. Different crystal rotation rates varying between 0 and 30 rpm and stationary or -2 rpm crucible rotation rates are considered. The results show that the crystal and crucible rotation rates …


Load Sharing Based On Moving Roles In Multiagent Systems, Şebnem Bora, Ali̇ Murat Ti̇ryaki̇, Oğuz Di̇kenelli̇ Jan 2012

Load Sharing Based On Moving Roles In Multiagent Systems, Şebnem Bora, Ali̇ Murat Ti̇ryaki̇, Oğuz Di̇kenelli̇

Turkish Journal of Electrical Engineering and Computer Sciences

In this paper, we present a load-sharing approach based on the refactoring of agents. According to our approach, the role(s) that makes an agent overloaded is identified and transferred to less loaded agents. The excess workload of this heavily loaded agent is then transferred to the new agent. This approach defines a new agent, called the ``monitor agent,'' which monitors the workload of agents in the organization and decides about the refactoring of the agents. The monitor agent uses the platform ontology, which explicitly describes the components of the agent organization, including agents and their roles, plans, and workloads. This …


A Comparative Study Of Blind And Nonblind Trainings In A Single-Carrier Wimax (Ieee 802.16-2004) Radio, Ali̇ Özen Jan 2012

A Comparative Study Of Blind And Nonblind Trainings In A Single-Carrier Wimax (Ieee 802.16-2004) Radio, Ali̇ Özen

Turkish Journal of Electrical Engineering and Computer Sciences

Experimental and theoretical bit error rate performance evaluations of blind and nonblind training techniques are obtained by using a single-carrier WiMAX (IEEE 802.16-2004) radio for high-order quadrature amplitude modulation channels. Instead of using a certain type of channel profile, this study concentrates on true frequency-selective Rayleigh fading channels and also evaluates the fast fading scenario of Rayleigh channels in a real-time WiMAX radio environment around 3.5 GHz. The popular least mean squares (LMS) learning algorithm and constant modulus learning algorithm (CMA) are used as benchmarks in an investigation of nonblind and blind trainings, namely recursive least squares (RLS), modified-CMA, normalized-CMA, …


Optimization Of Pilot Tones Using Differential Evolution Algorithm In Mimo-Ofdm Systems, Muhammet Nuri̇ Seyman, Necmi̇ Taşpinar Jan 2012

Optimization Of Pilot Tones Using Differential Evolution Algorithm In Mimo-Ofdm Systems, Muhammet Nuri̇ Seyman, Necmi̇ Taşpinar

Turkish Journal of Electrical Engineering and Computer Sciences

In this paper, we propose a differential evolution (DE) algorithm for optimizing the placement and power of the pilot tones that are utilized by a least square (LS) algorithm for channel estimation in multiple-input and multiple-output orthogonal frequency-division multiplexing (MIMO-OFDM) systems. Computer simulations demonstrated that the performance of the LS algorithm was increased by optimizing the pilot tones with the DE algorithm instead of locating them orthogonally. We used the upper bound of the mean square error (MSE) as a fitness function of the DE algorithm for optimization tasks. With the use of an upper bound, it is not necessary …


An Improved Fastslam Framework Using Soft Computing, Ramazan Havangi, Mohammad Ali Nekoui, Mohammad Teshnehlab Jan 2012

An Improved Fastslam Framework Using Soft Computing, Ramazan Havangi, Mohammad Ali Nekoui, Mohammad Teshnehlab

Turkish Journal of Electrical Engineering and Computer Sciences

FastSLAM is a framework for simultaneous localization and mapping (SLAM) using a Rao-Blackwellized particle filter. However, FastSLAM degenerates over time. This degeneracy is due to the fact that a particle set estimating the pose of the robot loses its diversity. One of the main reasons for losing particle diversity in FastSLAM is sample impoverishment. In this case, most of the particle weights are insignificant. Another problem of FastSLAM relates to the design of an extended Kalman filter (EKF) for the landmark position's estimation. The performance of the EKF and the quality of the estimation depend heavily on correct a priori …


A Video Encoder Design Combining Edge-Adaptive Lifting And Scalable Block-Matching With Motion Compensation, Sedat Telçeken, Ömer Nezi̇h Gerek Jan 2012

A Video Encoder Design Combining Edge-Adaptive Lifting And Scalable Block-Matching With Motion Compensation, Sedat Telçeken, Ömer Nezi̇h Gerek

Turkish Journal of Electrical Engineering and Computer Sciences

This study aimed to achieve video compression by using a novel lifting-based hybrid encoder that also uses motion compensation. The proposed encoder separates video frames into temporal groups, within which certain frames are selected for producing temporal and spatial predictions over the rest of the frames. The predictions utilize spatiotemporal lifting together with motion compensation. The combination of spatial information with temporal changes is inspired from the idea of edge-adaptive lifting, which alters prediction directions in images. A further incorporation of well-known block-matching methods with different levels was observed to improve the performance. To provide the first compression results, unpredicted …


Mathematical Modeling And Vertical Flight Control Of A Tilt-Wing Uav, Kaan Taha Öner, Ertuğrul Çeti̇nsoy, Efe Sirimoğlu, Cevdet Hançer, Mustafa Ünel, Mahmut Faruk Akşi̇t, Kayhan Gülez, İlyas Kandemi̇r Jan 2012

Mathematical Modeling And Vertical Flight Control Of A Tilt-Wing Uav, Kaan Taha Öner, Ertuğrul Çeti̇nsoy, Efe Sirimoğlu, Cevdet Hançer, Mustafa Ünel, Mahmut Faruk Akşi̇t, Kayhan Gülez, İlyas Kandemi̇r

Turkish Journal of Electrical Engineering and Computer Sciences

This paper presents a mathematical model and vertical flight control algorithms for a new tilt-wing unmanned aerial vehicle (UAV). The vehicle is capable of vertical take-off and landing (VTOL). Due to its tilt-wing structure, it can also fly horizontally. The mathematical model of the vehicle is obtained using Newton-Euler formulation. A gravity compensated PID controller is designed for altitude control, and three PID controllers are designed for attitude stabilization of the vehicle. Performances of these controllers are found to be quite satisfactory as demonstrated by indoor and outdoor flight experiments.


Design Parameters And Uncertainty Bound Estimation Functions For Adaptive-Robust Control Of Robot Manipulators, Recep Burkan Jan 2012

Design Parameters And Uncertainty Bound Estimation Functions For Adaptive-Robust Control Of Robot Manipulators, Recep Burkan

Turkish Journal of Electrical Engineering and Computer Sciences

In this paper, a parameter and uncertainty bound estimation functions for adaptive-robust control of robot manipulators are developed. A Lyapunov function is defined and parameters and uncertainty bound estimation functions are developed based on the Lyapunov function. Thus, stability of an uncertain system is guaranteed and uniform boundedness of the tracking error is achieved. As distinct from previous parameter and bound estimation laws, the parameters and uncertainty bounds are updated as a function of a combination of trigonometric function depending on robot parameters and tracking error. Based on the same Lyapunov function, a robust control law is also defined and …


Analysis Of Orthogonal Matching Pursuit Based Subsurface Imaging For Compressive Ground Penetrating Radars, Mehmet Ali̇ Çağri Tuncer, Ali̇ Cafer Gürbüz Jan 2012

Analysis Of Orthogonal Matching Pursuit Based Subsurface Imaging For Compressive Ground Penetrating Radars, Mehmet Ali̇ Çağri Tuncer, Ali̇ Cafer Gürbüz

Turkish Journal of Electrical Engineering and Computer Sciences

It is shown that compressive sensing (CS) theory can be used for subsurface imaging in stepped frequency ground penetrating radars (GPR), resulting in robust sparse images, using fewer measurements. Although the data acquisition time is decreased by CS, the computational complexity of the minimization based imaging algorithm is too costly, which makes the algorithm useless, especially for extensive discretization or 3D imaging. In this paper, a greedy alternative, orthogonal matching pursuit (OMP) is used for imaging subsurface and its performance under various conditions is compared to CS imaging method. Results show that OMP could reconstruct sparse signals robustly as well …


A Hybrid Approach For Power Quality Monitoring, Okan Özgönenel, Ümi̇t Kemaletti̇n Terzi̇, Abdesh Khan Jan 2012

A Hybrid Approach For Power Quality Monitoring, Okan Özgönenel, Ümi̇t Kemaletti̇n Terzi̇, Abdesh Khan

Turkish Journal of Electrical Engineering and Computer Sciences

This paper presents a novel hybrid approach for detection of power quality (PQ) disturbances. The proposed hybrid algorithm is based on applications of principle component analysis, discrete wavelet transform, and fast Fourier transform on voltage and current waveforms. The proposed PQ monitoring (PQM) software uses 3-phase voltage and current signals in order to detect possible power disturbances such as voltage sag, flicker, harmonics, transients, DC component, and electromagnetic interference. The test results demonstrate the potential of the proposed hybrid technique for PQM andPQ assessment.


A Pseudo Spot Price Of Electricity Algorithm Applied To Environmental Economic Active Power Dispatch Problem, Celal Yaşar Jan 2012

A Pseudo Spot Price Of Electricity Algorithm Applied To Environmental Economic Active Power Dispatch Problem, Celal Yaşar

Turkish Journal of Electrical Engineering and Computer Sciences

In this study, an environmental economic active power dispatch problem is transformed into an optimization problem with a single-objective function by applying the weighted sum method (WSM) and the conic scalarization method (CSM). A pseudo spot price of electricity algorithm (PSPA) is used to solve the transformed problem. This is demonstrated on an example problem, which is a lossy electrical power system having only thermal units The WSM and CSM methods are applied to the example problem, and the weight factor values of these methods is increased from 0 to 1 by a step size of 0.1. For each possible …


Improvement Of Smart Card Based Password Authentication Scheme For Multiserver Environments, Zuowen Tan Jan 2012

Improvement Of Smart Card Based Password Authentication Scheme For Multiserver Environments, Zuowen Tan

Turkish Journal of Electrical Engineering and Computer Sciences

In multiserver (MS) environments, it is preferable for a remote user to login to different service provider servers by keying in the same password. Recently, Wang et al. proposed an improvement on the dynamic identity-based smart card authentication scheme of Liao and Wang for MS environments. Sandeep et al. improved the dynamic identity-based smart card authentication scheme of Hsiang et al. for MS architecture. However, we found that the schemes of Wang et al. and Sandeep et al. failed to provide service provider server authentication, perfect forward security, and login scalability. In addition, the scheme of Sandeep et al. was …


Vibration Analysis Of Base Structure On Sins Using Pzt Actuators, Bin Zheng, Jianfeng Yang Jan 2012

Vibration Analysis Of Base Structure On Sins Using Pzt Actuators, Bin Zheng, Jianfeng Yang

Turkish Journal of Electrical Engineering and Computer Sciences

A steel plate bonded with lead zirconate titanate (PZT) actuators was studied on the basis of finite element methods (FEMs). The damping amplitudes of this plate bonded with PZT actuators were obtained at different locations and under different control conditions by analyzing the distribution of the PZT plate's strain tensor in the first 4 modes. Furthermore, to reduce the unwanted disturbance and mitigate the errors from sensors, a base structure of the missile's strapdown inertial navigation system (SINS) is also proposed. The results show that the vibration control can be enhanced by increasing the number of the PZT actuators bonded. …


Voltage Stability Via Energy Function Analysis On Reduced Order Model Of Power System, Ahmet Çi̇fci̇, Yilmaz Uyaroğlu, Mehmet Ali̇ Yalçin Jan 2012

Voltage Stability Via Energy Function Analysis On Reduced Order Model Of Power System, Ahmet Çi̇fci̇, Yilmaz Uyaroğlu, Mehmet Ali̇ Yalçin

Turkish Journal of Electrical Engineering and Computer Sciences

A power system is a typical nonlinear dynamical system and voltage stability is an important subject of power system stability. This paper describes the use of the variable gradient method in a reduced order model of a single-machine infinite-bus power system. Additionally, the system's Lyapunov (energy) function is created and thus the system's energy level changes' effects on the system's stability are shown using the MACSYMA program. The Lyapunov function allows the determination of stability for nonlinear systems without the need to find exact solutions.


A Novel Structure To Enhance Magnetic Force And Velocity In Tubular Linear Reluctance Motor, Ali Mosallanejad, Abbas Shoulaie Jan 2012

A Novel Structure To Enhance Magnetic Force And Velocity In Tubular Linear Reluctance Motor, Ali Mosallanejad, Abbas Shoulaie

Turkish Journal of Electrical Engineering and Computer Sciences

In this paper, a novel design for a tubular linear reluctance motor (TLRM) has been developed. This paper presents a novel structure to enhance magnetic force and velocity in a TLRM. The new structure is accomplished through some changes in a TLRM, which results in a step winding structure. Comparing the proposed motor and the typical motor performances, it is proven that the proposed motor has better performance. For dynamic modeling of the proposed TLRM and to obtain the motor output characteristics, the method used for inductance profile calculation is described. The performance improvements in the proposed motor are evaluated …


A Novel Motor Speed Calculation Method Using Square Wave Speed Sensor Signals Via Fast Fourier Transform, Hayri̇ Arabaci, Osman Bi̇lgi̇n Jan 2012

A Novel Motor Speed Calculation Method Using Square Wave Speed Sensor Signals Via Fast Fourier Transform, Hayri̇ Arabaci, Osman Bi̇lgi̇n

Turkish Journal of Electrical Engineering and Computer Sciences

This paper presents a novel motor speed measurement method and experimental results using the fast Fourier transform (FFT). Motor speed is obtained using the square wave output signal of a speed sensor. In the proposed method, the speed can be measured in a wide range, and transient speed changes can also be clearly observed. The experiments were conducted during start-up and in steady state. The sampled speed data were transformed to frequency spectrums using the FFT. The frequency, which corresponds to the maximum amplitude in the spectrum, was used to calculate the motor speed. The test results show that the …


Broken Rotor Bar Fault Detection In Inverter-Fed Squirrel Cage Induction Motors Using Stator Current Analysis And Fuzzy Logic, Mehmet Akar, İlyas Çankaya Jan 2012

Broken Rotor Bar Fault Detection In Inverter-Fed Squirrel Cage Induction Motors Using Stator Current Analysis And Fuzzy Logic, Mehmet Akar, İlyas Çankaya

Turkish Journal of Electrical Engineering and Computer Sciences

This paper presents the implementation of broken rotor bar fault detection in an inverter-fed induction motor using motor current signal analysis (MCSA) and prognosis with fuzzy logic. Recently, inverter-fed induction motors have become very popular because of their adjustable speed drive. They have been used in many vital control applications such as rolling mills, variable speed compressors, pumps, and fans. The condition monitoring of these motors can significantly reduce the cost of maintenance in the early detection of faults. In this study, MCSA is applied to an inverter-fed induction motor to detect broken rotor bar faults. The diagnosis of a …


Abstract Feature Extraction For Text Classification, Göksel Bi̇ri̇ci̇k, Banu Di̇ri̇, Ahmet Coşkun Sönmez Jan 2012

Abstract Feature Extraction For Text Classification, Göksel Bi̇ri̇ci̇k, Banu Di̇ri̇, Ahmet Coşkun Sönmez

Turkish Journal of Electrical Engineering and Computer Sciences

Feature selection and extraction are frequently used solutions to overcome the curse of dimensionality in text classification problems. We introduce an extraction method that summarizes the features of the document samples, where the new features aggregate information about how much evidence there is in a document, for each class. We project the high dimensional features of documents onto a new feature space having dimensions equal to the number of classes in order to form the abstract features. We test our method on 7 different text classification algorithms, with different classifier design approaches. We examine performances of the classifiers applied on …


Observer Path Design By Imitation Of Competing Constraints For Bearing Only Tracking, Ridvan Gürcan, Mesut Kartal Jan 2012

Observer Path Design By Imitation Of Competing Constraints For Bearing Only Tracking, Ridvan Gürcan, Mesut Kartal

Turkish Journal of Electrical Engineering and Computer Sciences

In the bearing only tracking (BOT) problem the observer tries to estimate the position of the target. The observer maneuver is a requirement to guarantee the uniqueness of the estimation. Determining an observer maneuver for BOT is a difficult problem due to its nonlinear nature. This paper proposes a new method that combines the reference BOT scenarios as a priori knowledge with the incoming bearing measurements to obtain an observer maneuver in a generic optimization framework. The use of a priori knowledge makes the observer maneuver design more realistic. The maneuver recommendation process uses the imitation of competing constraints. In …


On The Degradation Of Ota-C--Based Cmos Low-Power Filter Circuits For Biomedical Instrumentation, Yasi̇n Özçelep, Ayten Kuntman, Hulusi̇ Hakan Kuntman Jan 2012

On The Degradation Of Ota-C--Based Cmos Low-Power Filter Circuits For Biomedical Instrumentation, Yasi̇n Özçelep, Ayten Kuntman, Hulusi̇ Hakan Kuntman

Turkish Journal of Electrical Engineering and Computer Sciences

In this work, we propose a degraded transistor-based circuit degradation simulation method to investigate the degradation effect in complementary metal-oxide semiconductor (CMOS) biomedical devices. The method is demonstrated on an operational transconductance amplifier and capacitor (OTA-C)-based CMOS filter structure. First, we simulate the degradation of the symmetrical CMOS OTA by determining the degraded transistors in the structure. The simulation results are compared with the experimental results of our previous study. First- and second-order low-pass filter degradations are also simulated to demonstrate the accuracy of the proposed method. Finally, the degradation in the electroencephalogram band-pass filter and its effect on the …


Improved Computerized Evaluation Of Abdominal Aortic Aneurysm, Semi̇h Utku, Hulusi̇ Baysal, Reyat Yilmaz, Aytaç Gülcü, Recep Alp Kut, Ahmet Yi̇ği̇t Göktay Jan 2012

Improved Computerized Evaluation Of Abdominal Aortic Aneurysm, Semi̇h Utku, Hulusi̇ Baysal, Reyat Yilmaz, Aytaç Gülcü, Recep Alp Kut, Ahmet Yi̇ği̇t Göktay

Turkish Journal of Electrical Engineering and Computer Sciences

Accurate measurements of arterial anatomy are emerging as the most important determinants of endovascular abdominal aneurysm repair. It is quite difficult to define and measure arterial anatomy features quantitatively due to the complex structure of the aneurysm and insufficient visual feedback. During decision making, to assist operators in diagnosing abdominal aortic aneurysms, a specialized preprocessing Abdominal Aortic Aneurysm Measurement and Evaluation Tool (AMET) was developed. AMET provides visual interfaces with broad measurement capabilities to generate a 3D model of the aorta for a better diagnosis and accurate stent selection. The accuracy and usability of the tool was tested with a …


Training Data Optimization For Anns Using Genetic Algorithms To Enhance Mppt Efficiency Of A Stand-Alone Pv System, Ahmet Afşi̇n Kulaksiz, Ramazan Akkaya Jan 2012

Training Data Optimization For Anns Using Genetic Algorithms To Enhance Mppt Efficiency Of A Stand-Alone Pv System, Ahmet Afşi̇n Kulaksiz, Ramazan Akkaya

Turkish Journal of Electrical Engineering and Computer Sciences

Maximum power point tracking (MPPT) algorithms are used to force photovoltaic (PV) modules to operate at their maximum power points for all environmental conditions. In artificial neural network (ANN)-based algorithms, the maximum power points are acquired by designing ANN models for PV modules. However, the parameters of PV modules are not always provided by the manufacturer and cannot be obtained readily by the user. Experimental measurements implemented in the overall PV system may be used to obtain the ANN dataset. One drawback of this method is that the generalization ability of the neural network usually degrades and some data reducing …