Relativistic Electromagnetism In Rotating Media,
2010
TÜBİTAK
Relativistic Electromagnetism In Rotating Media, Pierre Hillion
Turkish Journal of Electrical Engineering and Computer Sciences
This work concerns relativistic electromagnetism in a cylindrical Frenet-Serret frame. The tensor formalism of Maxwell's equations and electromagnetic fields in a vacuum is first developed in terms of cylindrical coordinates and afterwards applied to a rotating frame using the relativistic Trocheris-Takeno description of rotations. The metric ds^2 = g_{\mu \nu} dx^{\mu} dx^{\nu} of this frame is then obtained to find the determinant g of the g_{\mu \nu} matrix intervening in the relativistic Maxwell's equations, where the Greek indices take on the values 1,2,3,4. The propagation of harmonic cylindrical waves in rotating media is analyzed and it is shown that these …
A Power Quality Monitoring System Based On Matlab Server Pages,
2010
TÜBİTAK
A Power Quality Monitoring System Based On Matlab Server Pages, Bülent Vural, Ali̇ Kizil, Mehmet Uzunoğlu
Turkish Journal of Electrical Engineering and Computer Sciences
The power quality (PQ) requirement is one of the most important issues for power companies and their customers. Continuously monitoring the PQ from remote and distributed centers will help to improve the PQ. In this study, a remote power quality monitoring system for low voltage sub-networks is developed using MATLAB Server Pages (MSP). MATLAB Server Pages, which is an open source technical web programming language, combines MATLAB with integrated J2EE specifications. The proposed PQ monitoring system uses the MATLAB HTML tag library and the data captured by the DAQ hardware to evaluate the Power Quality parameters. The proposed system can …
The Effect Of Heat On The Metallurgical Structure And B-H Characteristic Of (Stator) Armature With Iron-Silicon Alloy In Electric Machines, Fevzi̇ Kentli̇, Ümi̇t Kemaletti̇n Terzi̇
Turkish Journal of Electrical Engineering and Computer Sciences
Coils in electric machines are varnished for insulation after winding. These varnished coils are formed in stiff construction in slots. Under heavy-duty operating conditions, all or part of some coils may be burnt or broken. Thermal method is one of several ways to remove the defective coils. In this method, current is passed through the defective coils by an autotransformer (variac) until all the varnish of the coils is burned. If all the coils are out of order, the varnish is burned by replacing the stator or armature in a burning room. Consequently, defective coils in the stator (armature) slots …
Nonlinear Dynamic Analysis Of Mitral Valve Doppler Signals: Surrogate Data Analysis,
2010
TÜBİTAK
Nonlinear Dynamic Analysis Of Mitral Valve Doppler Signals: Surrogate Data Analysis, Esma Uzunhi̇sarcikli
Turkish Journal of Electrical Engineering and Computer Sciences
In our study, the nonlinear dynamics of mitral valve Doppler signals from 32 healthy and 28 patients with mitral valve stenosis was evaluated using by the computation of Lyapunov exponents, correlation dimension values and surrogate data analysis. Two chaotic features are compared for healthy and patient subjects. It was found that the largest Lyapunov exponent and correlation dimension values derived from patient subjects were larger than that of healthy subjects (\rho < 0.005). Surrogate data analysis was performed to determine the chaotic dynamics of Doppler signals. It was observed that the original and surrogate data have similar spectral features. Receiver operating characteristic (ROC) curves were used to evaluate the nonlinearity character Area Under the curve (AUC) values were obtained as 0.99 and 0.978 for the largest Lyapunov exponent and correlation dimension values, respectively. According to these results, Doppler signals have a nonlinear dynamic property and the largest Lyapunov exponent. Correlation dimension features can be used to detect the change in blood flow velocity of patients with mitral valve stenosis.
Remote Sensing Applications Of Hf Skywave Radar: The Australian Experience,
2010
TÜBİTAK
Remote Sensing Applications Of Hf Skywave Radar: The Australian Experience, Stuart Anderson
Turkish Journal of Electrical Engineering and Computer Sciences
Australia has conducted research into over-the-horizon radar (OTHR) for almost sixty years. Early programs focused exclusively on military capabilities, such as the detection of aircraft, missiles and ships, but in 1974 a team was formed to design a new OTHR for which a remote sensing mission was proposed. Oceanic wind mapping experiments in 1977-78 yielded promising results so remote sensing became a recognised mission assigned to the new radar, known as Jindalee Stage B. This capability was progressively expanded over the period 1982-87 to include mapping of wave height and other oceanographic variables. A real-time data link to the Australian …
Dual-Use Of Compact Hf Radars For The Detection Of Mid- And Large-Size Vessels,
2010
TÜBİTAK
Dual-Use Of Compact Hf Radars For The Detection Of Mid- And Large-Size Vessels, Hugh Roarty, Don Barrick, Josh Kohut, Scott Glenn
Turkish Journal of Electrical Engineering and Computer Sciences
This paper describes the development of the SeaSonde High Frequency Radar system into a dual-use application for the mapping of ocean surface currents and detection of ships at sea. This development entailed the creation of a new radar waveform that would permit this dual-use as well as a detection algorithm to identify the ships in the radar spectra. The detection algorithm utilizes two methods for calculating a background signal level: an infinite impulse response (IIR) filter and a two-dimensional median filter. These two methods are employed simultaneously with multiple length averaging times to maximize the number of detections. The initial …
A Review Of High Frequency Surface Wave Radar For Detection And Tracking Of Ships,
2010
TÜBİTAK
A Review Of High Frequency Surface Wave Radar For Detection And Tracking Of Ships, Tony Ponsford, Jian Wang
Turkish Journal of Electrical Engineering and Computer Sciences
In today's resource-driven economy, maritime nations are claiming economic borders that extend beyond the continental shelf or the 200 nautical mile (nm) Exclusive Economic Zone (EEZ). However, claiming such large economic area places responsibilities on the parent nation to exercise jurisdiction through surveillance and enforcement. The requirement to see beyond the horizon has long been a goal of maritime security forces. Today, this is largely dependent on cooperative vessels voluntarily communicating their intentions to local shore-side authorities, as well as on those vessel sightings reported by patrollers. Recent advances in technology provide maritime nations with options to provide more systematic …
Nonlinear Scattering At Hf: Prospects For Exploitation In Oth Radar Systems,
2010
TÜBİTAK
Nonlinear Scattering At Hf: Prospects For Exploitation In Oth Radar Systems, Stuart Anderson
Turkish Journal of Electrical Engineering and Computer Sciences
HF skywave `over-the-horizon' radars experience exceptionally high levels of clutter from the earth's surface as a consequence of their `look-down' propagation geometry. While Doppler processing is effective in separating aircraft echoes from the clutter, thereby enabling detection, the same does not always hold for slow moving targets. In particular, ship echoes occupy the same region of Doppler space as the sea clutter, so the likelihood of target echo obscuration is high. By exploiting the known dependence of the characteristic spectral form of the clutter Doppler spectrum on radar frequency and other parameters, HF radars can maximise the prospects for detectability …
Radar Cross-Section (Rcs) Analysis Of High Frequency Surface Wave Radar Targets,
2010
TÜBİTAK
Radar Cross-Section (Rcs) Analysis Of High Frequency Surface Wave Radar Targets, Gonca Çakir, Levent Sevgi̇
Turkish Journal of Electrical Engineering and Computer Sciences
Realistic high frequency surface wave radar (HFSWR) targets are investigated numerically in terms of electromagnetic wave -- target interactions. Radar cross sections (RCS) of these targets are simulated via both the finite-difference time-domain (FDTD) method and the Method of Moments (MoM). The virtual RCS prediction tool that was introduced in previous work is used for these investigations. The virtual tool automatically creates the discrete FDTD model of the target under investigation and performs the FDTD RCS analysis. It also automatically constructs a MoM wire grid model of the target; therefore, it is also possible to compare FDTD results against the …
Propagation Modeling And Path Loss Prediction Tools For High Frequency Surface Wave Radars,
2010
TÜBİTAK
Propagation Modeling And Path Loss Prediction Tools For High Frequency Surface Wave Radars, Gökhan Apaydin, Levent Sevgi̇
Turkish Journal of Electrical Engineering and Computer Sciences
Propagation modeling and simulation approaches for the use of High Frequency Surface Wave Radar (HFSWR) are discussed. HFSWR uses vertically polarized surface waves along multi-mixed paths in the lower HF band (3 MHz - 15 MHz). Various numerical propagators are reviewed with an early analytical model. Split Step Fast Fourier Transformation, finite- difference, and finite-element solutions of the well-known one-way, forward propagation Parabolic Equation (PE) model are presented. MATLAB-based numerical propagation prediction tools based on these models are listed. Tests and comparisons among these analytical and numerical tools are given for some canonical surface wave propagation scenarios. The Millington effect …
Antenna Systems With Beam Forming And Beam Steering Capabilities For Hf Skywave Radars,
2010
TÜBİTAK
Antenna Systems With Beam Forming And Beam Steering Capabilities For Hf Skywave Radars, Çağatay Uluişik
Turkish Journal of Electrical Engineering and Computer Sciences
Radiation characteristics of linearly phased, periodic, planar dipole arrays, which can be used as transmitting/receiving antenna systems for HF skywave radars, are investigated. Rectangular, triangular and trapezoidal arrays are proposed in obtaining different beam shapes in the desired directions. Beam steering is achieved by adjusting the inter-element phase increments coherently. The effects of vertical array-tilt with a desired take-off angle (TOA) \alpha are presented by a number of radiation pattern examples. The ground effect is investigated using the image theory by assuming the Earth's surface as perfectly electric conductor (PEC). Radiated fields are obtained using Floquet wave representations plus the …
New Approach Fpga-Based Implementation Of Discontinuous Svpwm},
2010
TÜBİTAK
New Approach Fpga-Based Implementation Of Discontinuous Svpwm}, Tole Sutikno, Auzani Jidin, Nik Rumzi Nik Idris
Turkish Journal of Electrical Engineering and Computer Sciences
The discontinuous space vector pulse-width modulation (DSVPWM) is a well-known technique offering lower switching losses than continuous SVPWM. At the same, average switching frequency, or a switching frequency 1.5 times higher than utilized in continuous SVPWM, the discontinuous SVPWM results in lower current harmonic distortions than that obtained in continuous SVPWM at high modulation indices. This paper is concerned with the design and realization of new FPGA approach based a 5-segment discontinuous SVPWM operated at 40 kHz switching frequency. It will be shown that the implementation of the discontinuous SVPWM utilized in FPGA, to execute some complex tasks, is simplified …
Hierarchical Fuzzy Controller Applied To Multi-Input Power System Stabilizer,
2010
TÜBİTAK
Hierarchical Fuzzy Controller Applied To Multi-Input Power System Stabilizer, Ebrahim Rasooli Anarmarzi, Mohammad Reza Feyzi, Mehrdad Tarafdar Hagh
Turkish Journal of Electrical Engineering and Computer Sciences
This paper proposes the application of a hierarchical fuzzy system (HFS) based on multi-input power system stabilizer (MPSS) in multi-machine environment. The number of rules increases exponentially with the number of variables in a standard fuzzy system. This problem is solved in the proposed HFS method. In this method, the total number of rules increases only linearly with the number of input variables. HFS consists of a number of low-dimensional fuzzy systems in a hierarchical form. In the MPSS, the deviation of reactive power \Delta Q is added to a \Delta P+ \Delta \omega input type Power System Stabilizer (PSS) …
Washout Filter Based Control For The Hodgkin-Huxley Nerve Cell Dynamics,
2010
TÜBİTAK
Washout Filter Based Control For The Hodgkin-Huxley Nerve Cell Dynamics, Reşat Özgür Doruk
Turkish Journal of Electrical Engineering and Computer Sciences
In this work we present a washout filter based control approach for stabilizing the oscillations in Hodgkin-Huxley type neurons. The oscillations occur due to the bifurcations that arise from the potassium and sodium channel conductance deviations. The MATCONT toolbox software environment was used for analysis of the bifurcation points in conjunction with MATLAB. The simulations of the Hodgkin-Huxley (HH) model at those points are provided to validate the results obtained from the MATCONT software. Then a washout filter is proposed to stabilize the oscillations occur at the Hopf bifurcation points where the external current injection is used to provide the …
A Robust Method For State Estimation Of Power System With Upfc,
2010
TÜBİTAK
A Robust Method For State Estimation Of Power System With Upfc, Mehrdad Tarafdar Hagh, Mehdi Ahmadi Jirdehi
Turkish Journal of Electrical Engineering and Computer Sciences
This paper presents a Least Absolute Value (LAV) state estimator for power system using a new method called Recursive Least Squares (RLS). Also, a suitable model is used for state estimation of power system that includes a Unified Power Flow Controller (UPFC). The IEEE 14-bus test system is used to show the validity of the proposed algorithm in estimation of power system states as well as the states of controllable parameters of UPFC.
A Small Scale Education Experiment Kit With Wind Generator-Pem Electrolyser System And Modelling,
2010
TÜBİTAK
A Small Scale Education Experiment Kit With Wind Generator-Pem Electrolyser System And Modelling, Özcan Atlam
Turkish Journal of Electrical Engineering and Computer Sciences
A small scale experiment wind energy kit is prepared in order to introduce renewable energy applications. The kit consists of a wind turbine with horizontal axis, a direct current (dc) motor as generator and variable wind excitation system. Performance characteristics of the wind system are defined for different wind speeds. It is found that at the highest 10 m/s wind excitation, the maximum turbine mechanical power from wind is about 0.30 W at 5.3 V., maximum output power of the generator is about 0.18 W and maximum electrical efficiency is about 7% at 4.27 V., wind turbine power coefficients C_p …
A Novel Method For Lung Segmentation On Chest Ct Images: Complex-Valued Artificial Neural Network With Complex Wavelet Transform, Murat Ceylan, Yüksel Özbay, Osman Nuri̇ Uçan, Erkan Yildirim
Turkish Journal of Electrical Engineering and Computer Sciences
Image segmentation is an important step in many computer vision algorithms. The objective of segmentation is to obtained an optimal region of convergences (ROC). Error in this stage will impact all higher level activities. This paper focuses on a new efficient method denoted as Complex-Valued Artificial Neural Network with Complex Wavelet Transform (CWT-CVANN) for the segmentation of lung region on chest CT images. In this combined architecture is composed of two cascade stages: feature extraction with various levels of complex wavelet transform and segmentation with complex-valued artificial neural network. Here, 32 CT images of 6 female and 26 male patients …
Fault Detection And Identification For Voltage Sag State Estimation In Power Systems,
2010
TÜBİTAK
Fault Detection And Identification For Voltage Sag State Estimation In Power Systems, Jamal Beiza, Seyed Hossein Hosseinian, Behrooz Vahidi
Turkish Journal of Electrical Engineering and Computer Sciences
This paper presents a novel approach for fault detection and identification in order to estimate voltage sag during a fault. One of the best approaches for voltage sag estimation is instantaneous voltage estimation. The approach uses traditional state estimation where redundant measurements are available. The proposed method is used to estimate voltage sag performance during a fault. At the fault duration, the grid topology is changed. In such a case the measurement matrix must be re-determined at the fault duration. The proposed approach is an efficient method for fault detection and identification which is based on residual analysis and topology …
Active Illumination And Appearance Model For Face Alignment,
2010
TÜBİTAK
Active Illumination And Appearance Model For Face Alignment, Muhi̇tti̇n Gökmen, Fati̇h Kahraman, Sune Darkner, Rasmus Larsen
Turkish Journal of Electrical Engineering and Computer Sciences
Illumination conditions have an explicit effect on the performance of face recognition systems. In particular, varying the illumination upon the face imposes such complex effects that the identification often fails to provide a stable performance level. In this paper, we propose an approach integrating face identity and illumination models in order to reach acceptable and stable face recognition rates. For this purpose, Active Appearance Model (AAM) and illumination model of faces are combined in order to obtain an illumination invariant face localization. The proposed method is an integrated Active Illumination and Appearance Model (AIA) which combines identity, illumination and shape …
Robust Feedback Design For Nonlinear Systems: A Survey,
2010
TÜBİTAK
Robust Feedback Design For Nonlinear Systems: A Survey, Alberto Isidori
Turkish Journal of Electrical Engineering and Computer Sciences
No abstract provided.
