Open Access. Powered by Scholars. Published by Universities.®

Engineering Commons

Open Access. Powered by Scholars. Published by Universities.®

Articles 1 - 30 of 74

Full-Text Articles in Engineering

Ellipsoid Based L_2 Controller Design For Lpv Systems With Saturating Actuators, İbrahi̇m Beklan Küçükdemi̇ral, Levent Ucun, Yavuz Eren, Haluk Görgün, Gali̇p Cansever Jan 2011

Ellipsoid Based L_2 Controller Design For Lpv Systems With Saturating Actuators, İbrahi̇m Beklan Küçükdemi̇ral, Levent Ucun, Yavuz Eren, Haluk Görgün, Gali̇p Cansever

Turkish Journal of Electrical Engineering and Computer Sciences

This paper addresses the L_2 gain control problem for disturbance attenuation in Linear Parameter Varying (LPV) Systems having saturating actuators when the system is subjected to L_2 disturbances. In the presented method, saturating actuator is expressed analytically with a convex hull of some linear feedback which let us construct L_2 control problem via Linear Matrix Inequalities (LMIs) which are obtained by some ellipsoids. It is shown that the stability and disturbance rejection capabilities of the control system are all measured by means of these nested ellipsoids where the inner ellipsoid covers the initial conditions for states whereas the outer ellipsoid …


Spoiler Effects Reduction With Using Active Power Filter On A Direct Torque Controlled Induction Machine, İbrahi̇m Alişkan, Kayhan Gülez, Yusuf Altun Jan 2011

Spoiler Effects Reduction With Using Active Power Filter On A Direct Torque Controlled Induction Machine, İbrahi̇m Alişkan, Kayhan Gülez, Yusuf Altun

Turkish Journal of Electrical Engineering and Computer Sciences

Harmonics, which may be placed in electrical systems, have important effects on performance parameters of electrical motors. In this paper, effects of electrical power system voltage harmonics on torque position of induction motors are dealt with. System modeling with Pulse Width Modulation (PWM) type Active Power Filter (APF) is used for reducing these effects. APF, as a subsystem, is placed into torque control system entrance to save the control system and induction motor output torque. Motor outputs, that are before-after APF connections, are handed for understanding effects of voltage harmonics. Since APF design was based on voltage harmonics, Electromagnetic Interference …


Linear Motor For Multi--Car Elevators: Design And Position Measurement, Çağri Gürbüz, Ender Kazan, Ahmet Onat, Sandor Markon Jan 2011

Linear Motor For Multi--Car Elevators: Design And Position Measurement, Çağri Gürbüz, Ender Kazan, Ahmet Onat, Sandor Markon

Turkish Journal of Electrical Engineering and Computer Sciences

Multi-car elevator is an emerging technology consisting of two or more elevator cars moving independently in an elevator hoistway, which has become more appealing as building heights increase. In this paper, the design and drive methodologies for a linear motor driven multi-car elevator system with independently moving cars is introduced together with experimental results. Additionally, a safety method developed for the linear motor elevator and the conditions necessary for its proper operation are discussed. The new results introduced in this paper are in the areas of the design method of the linear motor for multi-car elevator system, and the preliminary …


Active Vibration Control Of Seismic Excited Structural System Using Lmi-Based Mixed H_2/H_{\Infty} State Feedback Controller, Hakan Yazici, Rahmi̇ Güçlü Jan 2011

Active Vibration Control Of Seismic Excited Structural System Using Lmi-Based Mixed H_2/H_{\Infty} State Feedback Controller, Hakan Yazici, Rahmi̇ Güçlü

Turkish Journal of Electrical Engineering and Computer Sciences

This paper is concerned with the active vibration control of a four-degree-of-freedom structure, which is effected by earthquake. To obtain desired time history and frequency responses for solution of active vibration control problem, Linear Matrix Inequality (LMI) based state-feedback mixed H_2/H_{\infty} controller is designed in this study. The time history of ground motion of the Kobe earthquake in 1995, which is a disturbance input, is applied to modeled structure. At the end of the study, the time history of the storey displacements, velocities and frequency responses of both controlled and uncontrolled cases are presented and results are discussed. Performance of …


A Logic Method For Efficient Reduction Of The Space Complexity Of The Attribute Reduction Problem, Mehmet Hacibeyoğlu, Fati̇h Başçi̇ftçi̇, Şi̇rzat Kahramanli Jan 2011

A Logic Method For Efficient Reduction Of The Space Complexity Of The Attribute Reduction Problem, Mehmet Hacibeyoğlu, Fati̇h Başçi̇ftçi̇, Şi̇rzat Kahramanli

Turkish Journal of Electrical Engineering and Computer Sciences

The goal of attribute reduction is to find a minimal subset (MS) R of the condition attribute set C of a dataset such that R has the same classification power as C. It was proved that the number of MSs for a dataset with n attributes may be as large as (_{n/2}^n) and the generation of all of them is an NP-hard problem. The main reason for this is the intractable space complexity of the conversion of the discernibility function (DF) of a dataset to the disjunctive normal form (DNF). Our analysis of many DF-to-DNF conversion processes showed that approximately …


Papr Reduction Using Artificial Bee Colony Algorithm In Ofdm Systems, Necmi̇ Taşpinar, Dervi̇ş Karaboğa, Mahmut Yildirim, Bahri̇ye Akay Jan 2011

Papr Reduction Using Artificial Bee Colony Algorithm In Ofdm Systems, Necmi̇ Taşpinar, Dervi̇ş Karaboğa, Mahmut Yildirim, Bahri̇ye Akay

Turkish Journal of Electrical Engineering and Computer Sciences

Partial transmit sequence (PTS) is an attractive scheme for peak-to-average power ratio (PAPR) reduction in orthogonal frequency division multiplexing (OFDM) systems, but its high computational complexity to find optimum phase factors is the main drawback. In this paper, we propose PTS based on an artificial bee colony (ABC) algorithm (ABC-PTS) for reducing the computational complexity of the PTS in the OFDM system. The ABC-PTS was compared to conventional PTS using a random search strategy (RS-PTS) and optimum PTS. In addition, the bit error rate (BER) performance of the ABC-PTS was shown when a high power amplifier (HPA) was used for …


Co-Occurrence Matrix And Its Statistical Features As A New Approach For Face Recognition, Alaa Eleyan, Hasan Demirel Jan 2011

Co-Occurrence Matrix And Its Statistical Features As A New Approach For Face Recognition, Alaa Eleyan, Hasan Demirel

Turkish Journal of Electrical Engineering and Computer Sciences

In this paper, a new face recognition technique is introduced based on the gray-level co-occurrence matrix (GLCM). GLCM represents the distributions of the intensities and the information about relative positions of neighboring pixels of an image. We proposed two methods to extract feature vectors using GLCM for face classification. The first method extracts the well-known Haralick features from the GLCM, and the second method directly uses GLCM by converting the matrix into a vector that can be used in the classification process. The results demonstrate that the second method, which uses GLCM directly, is superior to the first method that …


Design And Ground Plane Optimization Of A Cpw-Fed Ultra-Wideband Antenna, Mohammed Al-Husseini, Ali Ramadan, Youssef Tawk, Ali El-Hajj, Karim Y. Kabalan Jan 2011

Design And Ground Plane Optimization Of A Cpw-Fed Ultra-Wideband Antenna, Mohammed Al-Husseini, Ali Ramadan, Youssef Tawk, Ali El-Hajj, Karim Y. Kabalan

Turkish Journal of Electrical Engineering and Computer Sciences

In this paper, an ultra-wideband antenna based on an egg-shaped conductor and a co-planar waveguide (CPW) feed is presented. The ground plane incorporates an egg-shaped slot with parametrized center and dimensions. By resizing the slot and moving its center, a slotted or a partial ground can be obtained. Based on this configuration, a parametric study that aims at achieving the best ultra-wideband (UWB) response of the antenna is done. The study shows that an excellent UWB response is achieved for a certain ground slot size, beyond which the response starts to degrade. However, as the slot size tends to infinity, …


Remote Mutual Authentication And Key Agreement Scheme Based On Elliptic Curve Cryptosystem, Eunjun Yoon Jan 2011

Remote Mutual Authentication And Key Agreement Scheme Based On Elliptic Curve Cryptosystem, Eunjun Yoon

Turkish Journal of Electrical Engineering and Computer Sciences

Remote mutual authentication is an important part of security, along with confidentiality and integrity, for systems that allow remote access over untrustworthy networks, like the Internet. In 2006, Shieh-Wang pointed out the weakness of Juang's remote mutual authentication scheme using smart card and further proposed a novel remote user authentication scheme using smart card. However, this paper demonstrates that Shieh-Wang's scheme still does not provide perfect forward secrecy and is vulnerable to a privileged insider's attack. We also present an improved scheme based on the Elliptic Curve Diffie-Hellman problem (ECDHP) and secure one-way hash function, in order to isolate such …


Minimization Of Load Shedding By Sequential Use Of Linear Programming And Particle Swarm Optimization, Mehrdad Tarafdar Hagh, Sadjad Galvani Jan 2011

Minimization Of Load Shedding By Sequential Use Of Linear Programming And Particle Swarm Optimization, Mehrdad Tarafdar Hagh, Sadjad Galvani

Turkish Journal of Electrical Engineering and Computer Sciences

Minimization of load shedding during contingency conditions is solved as an optimization problem. As a new topic, instead of local load shedding, total load shedding of a large power system is considered. Power generation rescheduling is considered to minimize the load shedding, as well. Different importance factors for buses are also considered. The linear programming method (LP) is used to solve this problem in a short period of time without considering some power system constraints. Particle swarm optimization (PSO) is also used to solve the problem by considering all power system constraints, but with a longer solving time. Finally, a …


Design Of Cdba-Based Active Polyphase Filter For Low-If Receiver Applications, Mehmet Sağbaş Jan 2011

Design Of Cdba-Based Active Polyphase Filter For Low-If Receiver Applications, Mehmet Sağbaş

Turkish Journal of Electrical Engineering and Computer Sciences

A novel first-order active-RC polyphase filter section, using current differencing buffered amplifiers (CDBAs), is presented. The section uses 6 resistors, 2 capacitors, and 2 CDBAs. The transfer function of the proposed section has a single pole and optionally a single zero. Increasing the number of cascading sections, any higher order polyphase filter can be realized. This paper also introduces the leakage caused by element deviation and the effects of the amplifier in nonideal cases. Furthermore, nonideal performances of the proposed filter section are tested with PSpice simulations.


A Vision Based Feedback Mechanism For 6-Dof Stewart Platform, Utku Büyükşahi̇n Jan 2011

A Vision Based Feedback Mechanism For 6-Dof Stewart Platform, Utku Büyükşahi̇n

Turkish Journal of Electrical Engineering and Computer Sciences

Eyes are the most ubiquitous sensors of humankind. However, ``Vision Based Sensors" are not as common as what this fact would suggest. A survey of the previous work on image processing would reveal that the bulk of the research in this area have been conducted since the year 2000. These facts clearly show that image processing is the technology of our century, and is very open to further development. In this work, a system that combines a classical mechanism of the 20th century with the recent technology of the 21st century is presented and the design, theoretical background, the software …


Delay-Dependent Stability Criteria For Interval Time-Varying Delay Systems With Nonuniform Delay Partitioning Approach, Mehmet Nur Alpaslan Parlakçi Jan 2011

Delay-Dependent Stability Criteria For Interval Time-Varying Delay Systems With Nonuniform Delay Partitioning Approach, Mehmet Nur Alpaslan Parlakçi

Turkish Journal of Electrical Engineering and Computer Sciences

This paper investigates the conservatism reduction of Lyapunov-Krasovskii based conditions for the stability of a class of interval time-varying delay systems. The main idea is based on the nonuniform decomposition of the integral terms of the Lyapunov-Krasovskii functional. The delay interval is decomposed into a finite number of nonuniform segments with some scaling parameters. Both differentiable delay case and nondifferentiable delay case and unknown delay derivative bound case are taken into consideration. Sufficient delay-dependent stability criteria are derived in terms of matrix inequalities. Two suboptimal delay fractionation schemes, namely, linearization with cone complementary technique and linearization under additional constraints are …


A Complete Motor Protection Algorithm Based On Pca And Ann: A Real Time Study, Okan Özgönenel, Turgay Yalçin Jan 2011

A Complete Motor Protection Algorithm Based On Pca And Ann: A Real Time Study, Okan Özgönenel, Turgay Yalçin

Turkish Journal of Electrical Engineering and Computer Sciences

Protection of an induction motor (IM) against possible faults, such as a stator winding fault, due to thermal deterioration, rotor bar and bearing failures, is very important in environments in which it is used intensively, as in industry as an actuator. In this work, a real time digital protection algorithm based on principal component analysis (PCA) and neural network method is presented for induction motors. The proposed protection algorithm covers internal winding faults (also known as stator faults), broken rotor bar faults, and bearing faults. Many laboratory experiments have been performed on a specially designed induction motor to evaluate the …


Online Speed Control Of A Brushless Ac Servomotor Based On Artificial Neural Networks, Si̇bel Partal, İbrahi̇m Şenol, Ahmet Faruk Bakan, Kamuran Nur Beki̇roğlu Jan 2011

Online Speed Control Of A Brushless Ac Servomotor Based On Artificial Neural Networks, Si̇bel Partal, İbrahi̇m Şenol, Ahmet Faruk Bakan, Kamuran Nur Beki̇roğlu

Turkish Journal of Electrical Engineering and Computer Sciences

In this paper, an alternative approach to speed estimation of brushless AC servomotors is presented. Speed control is realized in the following steps. First, the servomotor was mathematically modelled; the driver system was designed and speed control of the servomotor was accomplished with feedback. Next, a network structure representing the electrical and mechanical properties of the servomotor was built via Artificial Neural Network (ANN) and trained with the results of the first step. The weights obtained from the neural nwork training were inserted into the control algorithm in accordance with the ANN. Finally, speed estimation was achieved based on the …


Low-Complexity Parameters Estimator For Multiple 2d Domain Incoherently Distributed Sources, Xiansheng Guo, Qun Wan, Xiaofeng Shen, Heng Dou Jan 2011

Low-Complexity Parameters Estimator For Multiple 2d Domain Incoherently Distributed Sources, Xiansheng Guo, Qun Wan, Xiaofeng Shen, Heng Dou

Turkish Journal of Electrical Engineering and Computer Sciences

A new low-complexity parameters estimator for multiple two-dimensional (2D) domain incoherently distributed (ID) sources is presented. One 2D domain ID source is parameterized with four parameters, the central azimuth direction-of-arrival (DOA), azimuth angular spread, central elevation DOA and elevation angular spread. Based on the eigenstructure between the steering matrix and signal subspace, an average total least-squares via rotational invariance technique (TLS-ESPRIT) is used to estimate the central elevation DOA, and then a generalized multiple signal classification (GMUSIC) algorithm is derived to estimate the central azimuth DOA. Utilizing preliminary estimates obtained at a pre-processing stage, the angular spread parameters can be …


On The Existence Of Common Lyapunov Functions For Consensus Algorithms Based On Averaging, Mehmet Akar, Robert Shorten Jan 2011

On The Existence Of Common Lyapunov Functions For Consensus Algorithms Based On Averaging, Mehmet Akar, Robert Shorten

Turkish Journal of Electrical Engineering and Computer Sciences

This paper addresses distributed deterministic consensus algorithms based on averaging. We relate the conditions for achieving consensus to the existence of a common norm for a set of row-stochastic matrices associated with the original set of averaging matrices. For a system to achieve consensus, it is shown that this associated set of matrices should have a Common Lyapunov Function, even if the original set might not have one.


Decentralized Robust Load-Frequency Control Of Power System Based On Quantitative Feedback Theory, Aidin Sakhavati, Gevork Gharehpetian, Seyed Hossein Hosseini Jan 2011

Decentralized Robust Load-Frequency Control Of Power System Based On Quantitative Feedback Theory, Aidin Sakhavati, Gevork Gharehpetian, Seyed Hossein Hosseini

Turkish Journal of Electrical Engineering and Computer Sciences

This paper aims at investigating the problem of Load Frequency Control (LFC) in interconnected power systems in order to obtain robustness against uncertainties. A design method for a robust controller, based on Quantitative Feedback Theory (QFT), has been presented in this paper. For a two-area power system, the simulation results show that the system response with the proposed QFT controller exhibits transient response beyond PI controllers. It is also shown that the transient response of the tie line power can also be improved.


Measuring Traffic Flow And Classifying Vehicle Types: A Surveillance Video Based Approach, Erhan İnce Jan 2011

Measuring Traffic Flow And Classifying Vehicle Types: A Surveillance Video Based Approach, Erhan İnce

Turkish Journal of Electrical Engineering and Computer Sciences

The paper presents a vehicle counting method based on invariant moments and shadow aware foreground masks. Estimation of the background and the segmentation of foreground regions can be done using either the Mixture of Gaussians model (MoG) or an improved version of the Group Based Histogram (GBH) technique. The work demonstrates that, even though the improved GBH method delivers performance just as good as MoG, considering computational efficiency, MoG is more suitable. Shadow aware binary masks for each frame are formed by using background subtraction and shadow removal in the Hue Saturation and Value (HSV) domain. To determine new vehicles …


Design And Control Of The Humanoid Robot Suralp, Kemaletti̇n Erbatur, Utku Seven, Evri̇m Taşkiran, Özer Koca, Meti̇n Yilmaz, Mustafa Ünel, Güllü Kiziltaş Şendur, Asif Sabanovic, Ahmet Onat Jan 2011

Design And Control Of The Humanoid Robot Suralp, Kemaletti̇n Erbatur, Utku Seven, Evri̇m Taşkiran, Özer Koca, Meti̇n Yilmaz, Mustafa Ünel, Güllü Kiziltaş Şendur, Asif Sabanovic, Ahmet Onat

Turkish Journal of Electrical Engineering and Computer Sciences

SURALP is a 29 degrees-of-freedom full-body walking humanoid robot designed and constructed at Sabanci University - Turkey. The human-sized robot is actuated by DC motors, belt and pulley systems and Harmonic Drive reduction gears. The sensory equipment consists of joint encoders, force/torque sensors, inertial measurement systems and cameras. The control hardware is based on a dSpace digital signal processor. This paper reviews the design of this robot and presents experimental walking results. A posture zeroing procedure is followed after manual zeroing of the robot joints. Controllers for landing impact reduction, early landing trajectory modification, foot-ground orientation compliance, body inclination and …


Model Predictive Controller Design Of Hydrocracker Reactors, Di̇la Gökçe Jan 2011

Model Predictive Controller Design Of Hydrocracker Reactors, Di̇la Gökçe

Turkish Journal of Electrical Engineering and Computer Sciences

This study summarizes the design of a Model Predictive Controller (MPC) in Tüpraş, İzmit Refinery Hydrocracker Unit Reactors. Hydrocracking process, in which heavy vacuum gasoil is converted into lighter and valuable products at high temperature and pressure is described briefly. Controller design description, identification and modeling studies are examined and the model variables are presented. WABT (Weighted Average Bed Temperature) equalization and conversion increase are simulated, results are discussed.


Application Of A Hybrid Evolutionary Technique For Efficiency Determination Of A Submersible Induction Motor, Mümtaz Mutluer, Osman Bi̇lgi̇n Jan 2011

Application Of A Hybrid Evolutionary Technique For Efficiency Determination Of A Submersible Induction Motor, Mümtaz Mutluer, Osman Bi̇lgi̇n

Turkish Journal of Electrical Engineering and Computer Sciences

Electric motors are the largest consumers of electricity in plants and induction motors constitute nearly two-thirds of them. The replacement of in-service induction motors with more efficient ones is a very important strategy for energy savings and consequently nearly 30 different methods have been used to determine the efficiency of induction motors in the last 2 decades. This paper aims to develop the efficiency determination of a 20 Hp submersible induction motor. Due to getting perfect efficiency of the submersible induction motor, a robust hybrid evolutionary optimization technique, which consists of a genetic algorithm and simulated annealing, is used. The …


Statistical Significance Based Graph Cut Regularization For Medical Image Segmentation, Sema Candemi̇r, Yusuf Si̇nan Akgül Jan 2011

Statistical Significance Based Graph Cut Regularization For Medical Image Segmentation, Sema Candemi̇r, Yusuf Si̇nan Akgül

Turkish Journal of Electrical Engineering and Computer Sciences

Graph cut minimization formulates the image segmentation as a linear combination of problem constraints. The salient constraints of the computer vision problems are data and smoothness which are combined through a regularization parameter. The main task of the regularization parameter is to determine the weight of the smoothness constraint on the graph energy. However, the difference in functional forms of the constraints forces the regularization weight to balance the inharmonious relationship between the constraints. This paper proposes a new idea: bringing the data and smoothness terms on the common base decreases the difference between the constraint functions. Therefore the regularization …


Design And Evaluation Of A Query-Based Jamming Detection Algorithm For Wireless Sensor Networks, Murat Çakiroğlu, Ahmet Turan Özceri̇t Jan 2011

Design And Evaluation Of A Query-Based Jamming Detection Algorithm For Wireless Sensor Networks, Murat Çakiroğlu, Ahmet Turan Özceri̇t

Turkish Journal of Electrical Engineering and Computer Sciences

Jamming attacks, which are the main cause of data corruption and network blockages in wireless sensor networks (WSNs), are one of the most serious threats for WSNs. This type of attack not only blocks the ongoing communication in the network, but also causes the wireless nodes to exhaust their energy much earlier than expected. A countermeasure must be deployed against jamming attacks, especially in military and medical applications in which security breaches cannot be tolerated. In this paper, we have designed a new query-based jamming detection algorithm (QUJDA) to detect jamming attacks occurring in WSNs. QUJDA is an attack detection …


Analysis Of Frequency Characteristics Of Electrical Arcs On The Insulating Sheath Of The Adss Fiber Optic Cables, Cengi̇z Polat Uzunoğlu, İbrahi̇m Güneş, Mukden Uğur Jan 2011

Analysis Of Frequency Characteristics Of Electrical Arcs On The Insulating Sheath Of The Adss Fiber Optic Cables, Cengi̇z Polat Uzunoğlu, İbrahi̇m Güneş, Mukden Uğur

Turkish Journal of Electrical Engineering and Computer Sciences

The insulating outer-sheath of ADSS (All dielectric self supporting) cables used on high voltage transmission lines are often subjected to various environmental effects. The ageing process of cable sheath can be investigated by using the dry-band arcing test method under laboratory conditions. Dry-band arcing is the most common technique to determine the ageing period of insulating materials. Environmental effects such as rain, humidity, dew and ice produce various amounts of wet regions on the cable surface. Electrical arcs and hence degradations are occurred on the cable surface due to the enhanced electrical field with formation of wet regions. In this …


Stray Magnetic Field Distributed Around A Pmsm, Ali̇ Ahmed Adam, Kayhan Gülez, Seli̇m Köroğlu Jan 2011

Stray Magnetic Field Distributed Around A Pmsm, Ali̇ Ahmed Adam, Kayhan Gülez, Seli̇m Köroğlu

Turkish Journal of Electrical Engineering and Computer Sciences

In this work, the low frequency electromagnetic emission from permanent magnet synchronous motors is studied. The main objective is to provide a safety region for humans in the vicinity of these motors, especially as these motors are now being used widely in inhabited areas, where high flux densities are expected. In this study, a new proposed equivalent magnetic circuit is used to estimate the stray fields at the surface of the motor. The analysis showed that the emission of the stray field in the radial direction depends on the permeability of the stator body. Low values of permeability may result …


A Novel And Efficient Algorithm For Adaptive Filtering: Artificial Bee Colony Algorithm, Nurhan Karaboğa, Mehmet Bahadir Çeti̇nkaya Jan 2011

A Novel And Efficient Algorithm For Adaptive Filtering: Artificial Bee Colony Algorithm, Nurhan Karaboğa, Mehmet Bahadir Çeti̇nkaya

Turkish Journal of Electrical Engineering and Computer Sciences

The uni-modal error surfaces and intrinsic stable behaviors of adaptive finite impulse response (FIR) filters make gradient based algorithms very effective in the design of these filters. Gradient based design methods are well developed for the design of adaptive FIR filters and widely applied to the distinct areas such as noise cancellation, system identification and channel equalization. However, the studies on adaptive infinite impulse response (IIR) filters are not as common as adaptive FIR filters since the stability during the adaptation process may not be ensured in some applications, and the convergence to the optimal design is not always guaranteed …


New Srco With Explicit Current-Mode Output Using Two Ccs And Grounded Capacitors, D R. Bhaskar, Kasim K. Abdalla, Raj Senani Jan 2011

New Srco With Explicit Current-Mode Output Using Two Ccs And Grounded Capacitors, D R. Bhaskar, Kasim K. Abdalla, Raj Senani

Turkish Journal of Electrical Engineering and Computer Sciences

A new Grounded-Capacitor Single Resistance Controlled Sinusoidal Oscillator (SRCO) with explicit current output using two Current Conveyors (CCs) and five passive elements is presented. The proposed circuit offers (i) independent control of condition of oscillation and frequency of oscillation, (ii) low active and passive sensitivities, (iii) use of both the grounded capacitors (suitable for IC implementation) and (iv) reasonably good frequency stability. The workability of the proposed configuration has been confirmed by the PSPICE simulations.


Four Quadrant Fgmos Analog Multiplier, Si̇nem Keleş, Hulusi̇ Hakan Kuntman Jan 2011

Four Quadrant Fgmos Analog Multiplier, Si̇nem Keleş, Hulusi̇ Hakan Kuntman

Turkish Journal of Electrical Engineering and Computer Sciences

A novel four-quadrant analog multiplier using floating gate MOS (FGMOS) transistors operating in the saturation region is presented. The drain current is proportional to the square of the weighted sum of the input signals. This square law characteristic of the FGMOS transistor is used to implement the quarter square identity by utilizing only six FGMOS transistors. The main features of this remarkably simple multiplier circuit configuration are the large input signal range equal to 100% of the supply voltage, nonlinearity of 0.0081%, bandwidth of 1.4--1.5 Ghz and THD of maximum 2.67% (while the inputs are at their maximum values).


Asynchronous Signal Processing For Brain-Computer Interfaces, Seda Senay, Luis F. Chaparro, Mingui Sun, Robert Sclabassi, Aydin Akan Jan 2011

Asynchronous Signal Processing For Brain-Computer Interfaces, Seda Senay, Luis F. Chaparro, Mingui Sun, Robert Sclabassi, Aydin Akan

Turkish Journal of Electrical Engineering and Computer Sciences

Brain-computer interfaces (BCIs) provide a way to monitor and treat neurological diseases. An important application of BCIs is the monitoring and treatment of epilepsy, a neurological disorder characterized by recurrent unprovoked seizures, symptomatic of abnormal, excessive or synchronous neuronal activity in the brain. BCIs contain an array of sensors that gather and transmit data under the constrains of low-power and minimal data transmission. Asynchronous sigma delta modulators (ASDMs) are considered an alternative to synchronous analog to digital conversion. ASDMs are non-linear feedback systems that enable time-encoding of analog signals, from which the signal can be reconstructed. An efficient reconstruction of …