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2017

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Articles 11041 - 11070 of 12521

Full-Text Articles in Physical Sciences and Mathematics

Optimal Determination Of Island Boundaries Besides The Optimal Placement Of D-Statcom Devices And Dg Units, Sadeq Rabie, Hossein Afrakhte Jan 2017

Optimal Determination Of Island Boundaries Besides The Optimal Placement Of D-Statcom Devices And Dg Units, Sadeq Rabie, Hossein Afrakhte

Turkish Journal of Electrical Engineering and Computer Sciences

In this study, integration of three important concepts of distributed generation, D-FACTS devices, and microgrids are evaluated. The performance of a microgrid is dependent on its location, capacity, and placement of DG units and D-FACTS devices. In this paper a new method is proposed to simultaneously determine the optimal number, location, and capacity of DG units and D-STATCOM devices and optimal boundaries of electrical islands in the independent mode of microgrids. The main objective is to minimize the economic costs. The optimal locations of DG units and D-STATCOM devices should be determined to maximize the DG capacities with minimum loss …

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New Static Output Feedback Stabilization And Multivariable Pid-Controller Design Methods For Unstable Linear Systems Via An Ilmi Optimization Approach, Mehmet Nur Alpaslan Parlakçi, Elbrus Caferov Jan 2017

New Static Output Feedback Stabilization And Multivariable Pid-Controller Design Methods For Unstable Linear Systems Via An Ilmi Optimization Approach, Mehmet Nur Alpaslan Parlakçi, Elbrus Caferov

Turkish Journal of Electrical Engineering and Computer Sciences

The design problem of a static output feedback controller and multivariable proportional-integral-derivative (PID) controller is investigated for linear time-invariant systems (LTI). First, the static output feedback stabilization problem is taken into consideration and then an iterative linear matrix inequality (ILMI) algorithm is developed for the synthesis of the controller. Second, choosing a multivariable PID control law, the whole system is transformed into a new augmented system represented in the form of a static output feedback control system. This method allows us to convert the multivariable PID controller design problem into a static output feedback synthesis problem. Thus, the proposed ILMI …

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Neural Network Approach On Loss Minimization Control Of A Pmsm With Core Resistance Estimation, Hüseyi̇n Erdoğan, Mehmet Özdemi̇r Jan 2017

Neural Network Approach On Loss Minimization Control Of A Pmsm With Core Resistance Estimation, Hüseyi̇n Erdoğan, Mehmet Özdemi̇r

Turkish Journal of Electrical Engineering and Computer Sciences

Permanent magnet synchronous motors (PMSMs) are often used in industry for high-performance applications. Their key features are high power density, linear torque control capability, high efficiency, and fast dynamic response. Today, PMSMs are prevalent especially for their use in hybrid electric vehicles. Since operating the motor at high efficiency values is critically important for electric vehicles, as for all other applications, minimum loss control appears to be an inevitable requirement in PMSMs. In this study, a neural network-based intelligent minimum loss control technique is applied to a PMSM. It is shown by means of the results obtained that the total …

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Load Shedding Scheme Based On Frequency And Voltage Stability For An Islanding Operation Of A Distribution Network Connected To Mini-Hydro Generation, Norazliani Md Sapari, Hazlie Bin Mokhlis, Javed Ahmed Laghari, Ab Halim Abu Bakar, Hasmaini Mohamad, Mohd Rohaimi Mohd Dahalan Jan 2017

Load Shedding Scheme Based On Frequency And Voltage Stability For An Islanding Operation Of A Distribution Network Connected To Mini-Hydro Generation, Norazliani Md Sapari, Hazlie Bin Mokhlis, Javed Ahmed Laghari, Ab Halim Abu Bakar, Hasmaini Mohamad, Mohd Rohaimi Mohd Dahalan

Turkish Journal of Electrical Engineering and Computer Sciences

This paper presents a load shedding scheme (LSS) based on system frequency and voltage stability (VS). In the proposed scheme, the amount of power imbalance is determined using a rate of change of frequency, and the load shedding priority is carried out based on a VS index. The load with the highest tendency for voltage collapse (based on the index value) is given first priority to be shed. Thus, by shedding the most sensitive load, the distribution system can be saved from power collapse and then the system can return to its nominal state after load shedding. The proposed LSS …

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Model-Based Fault Analysis Of A High-Voltage Circuit Breaker Operating Mechanism, Ali Forootani, Ali Akbar Afzalian, Ali Nadian Ghohmshe Jan 2017

Model-Based Fault Analysis Of A High-Voltage Circuit Breaker Operating Mechanism, Ali Forootani, Ali Akbar Afzalian, Ali Nadian Ghohmshe

Turkish Journal of Electrical Engineering and Computer Sciences

In this paper, a dynamic model is developed for high-voltage circuit breakers to extract fault features and causes. Lagrange's method is applied using geometric equations of mechanism components to write the model. Unlike previous approaches, the proposed method reveals and analyzes all types of circuit breaker operating mechanism faults. Early fault detection, which is a vital requirement of the fault diagnosis system, becomes feasible by keeping track of changes in the contact travel curve in the proposed model. Resulting faults in the travel curve are analyzed mathematically in order to find out the exact origin of the fault. Field test …

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A Neuro-Fuzzy Controller For Grid-Connected Heavy-Duty Gas Turbine Power Plants, Mohamed Iqbal Mohamed Mustafa, Joseph Xavier Rayappan, Kanakaraj Jagannathan Jan 2017

A Neuro-Fuzzy Controller For Grid-Connected Heavy-Duty Gas Turbine Power Plants, Mohamed Iqbal Mohamed Mustafa, Joseph Xavier Rayappan, Kanakaraj Jagannathan

Turkish Journal of Electrical Engineering and Computer Sciences

Frequent load fluctuation and set-point variation may affect the stability of grid-connected heavy-duty gas turbine power plants. To overcome such problems, a novel neuro-fuzzy controller is proposed in this paper for single-shaft heavy-duty gas turbines ranging from 18.2 MW to 106.7 MW. A neuro-fuzzy controller was developed using a hybrid learning algorithm and the effectiveness of the controller for all heavy-duty gas turbine plants (5, 6, 7, and 9 series) is demonstrated against load disturbance and set-point variation in a grid-connected environment. Various time domain specifications and performance index criteria of the neuro-fuzzy controller are compared with that of a …

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A Novel Approach For Extracting Ideal Exemplars By Clustering For Massivetime-Ordered Datasets, Ömer Faruk Ertuğrul Jan 2017

A Novel Approach For Extracting Ideal Exemplars By Clustering For Massivetime-Ordered Datasets, Ömer Faruk Ertuğrul

Turkish Journal of Electrical Engineering and Computer Sciences

The number and length of massive datasets have increased day by day and this yields more complex machine learning stages due to the high computational costs. To decrease the computational cost many methods were proposed in the literature such as data condensing, feature selection, and filtering. Although clustering methods are generally employed to divide samples into groups, another way of data condensing is by determining ideal exemplars (or prototypes), which can be used instead of the whole dataset. In this study, first the efficiency of traditional data condensing by clustering approach was confirmed according to obtained accuracies and condensing ratios …

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Time-Time Matrix Z-Score Vector-Based Fault Analysis Method For Series-Compensated Transmission Lines, Oveis Asgari Gashteroodkhani, Behrooz Vahidi, Aydin Zaboli Jan 2017

Time-Time Matrix Z-Score Vector-Based Fault Analysis Method For Series-Compensated Transmission Lines, Oveis Asgari Gashteroodkhani, Behrooz Vahidi, Aydin Zaboli

Turkish Journal of Electrical Engineering and Computer Sciences

In this paper, a novel protection method based on time-time (TT) transform for thyristor-controlled series-compensated lines is presented. First, current signals at both sides of the sending and receiving ends are retrieved and processed through time-time domain transform (TT-transform), and a TT-matrix is produced. A proposed index is then compared with a defined threshold (THD) in order to determine fault occurrence and faulted phases. Within less than three cycles of the fault inception, a tripping signal can be sent that is acceptable for the speed of digital relays. After faulted phase selection, considering the TT-matrix of the faulted phases of …

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Late Fusion Of Facial Dynamics For Automatic Expression Recognition, Alessandra Bandrabur, Laura Florea, Cornel Florea, Matei Mancas Jan 2017

Late Fusion Of Facial Dynamics For Automatic Expression Recognition, Alessandra Bandrabur, Laura Florea, Cornel Florea, Matei Mancas

Turkish Journal of Electrical Engineering and Computer Sciences

Installment of a facial expression is associated with contractions and extensions of specific facial muscles. Noting that expression is about changes, we present a model for expression classification based on facial landmarks dynamics. Our model isolates the trajectory of facial fiducial points by wrapping them up in relevant features and discriminating among various alternatives with a machine learning classification system. The used features are geometric and temporal-based and the classification system is represented by a late fusion framework that combines several neural networks with binary responses. The proposed method is robust, being able to handle complex expression classes.

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Hesitant Fuzzy Pairwise Comparison For Software Cost Estimation: A Case Study In Turkey, Ayfer Başar Jan 2017

Hesitant Fuzzy Pairwise Comparison For Software Cost Estimation: A Case Study In Turkey, Ayfer Başar

Turkish Journal of Electrical Engineering and Computer Sciences

Estimating the cost of software is a complex process for almost all engineering companies. Uncertainties about development method, design, estimation process, data, and processing affect the accuracy of estimation. Underestimation results in fewer resources being committed than the project really needs, an unrealistic schedule, and low quality outputs. On the other hand, overestimation wastes resources and causes loss of customer credit. Thus, choosing the appropriate cost estimation method is crucial. Studies in the literature emphasize the importance of empirical, analytical methods and expert judgement. Certain cost estimation techniques have been widely studied in the literature. However, there are limited studies …

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A New Approach For Minimizing Torque Ripple In A Bldc Motor Drive With A Front End Ido Dc-Dc Converter, Ramya Amirthalingam, Balaji Mahadevan Jan 2017

A New Approach For Minimizing Torque Ripple In A Bldc Motor Drive With A Front End Ido Dc-Dc Converter, Ramya Amirthalingam, Balaji Mahadevan

Turkish Journal of Electrical Engineering and Computer Sciences

This paper proposes a front end integrated dual output (IDO) dc-dc converter for commutation torque ripple reduction in a permanent magnet brushless DC (BLDC) motor drive. The current ripple owed to the inductance and resistance of the motor during commutation instant results in torque ripple. In this work the dc link voltage of the converter is varied at commutation instants to minimize current ripple and hence torque ripple. The wider output range and faster response of the IDO converter make it a suitable choice as a front end converter for minimizing torque ripple. Simulation results validate the proposed converter for …

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Multiphase Segmentation Based On New Signed Pressure Force Functions And One Level Set Function, Haider Ali, Noor Badshah, Ke Chen, Gulzar Ali Khan, Nosheen Zikria Jan 2017

Multiphase Segmentation Based On New Signed Pressure Force Functions And One Level Set Function, Haider Ali, Noor Badshah, Ke Chen, Gulzar Ali Khan, Nosheen Zikria

Turkish Journal of Electrical Engineering and Computer Sciences

In this paper we propose a new model to detect multiple objects of various intensities in images having maximum, minimum, or middle-intensity background by evolving only one level set function. In this model, a new signed pressure force function based on novel generalized averages is used for segmentation of images with maximum or minimum intensity background. For images with middle-intensity backgrounds, which are indeed challenging for 2-phase models, we propose a new product generalized signed pressure force function. Finally, to give experimental and qualitative evidence, our model is tested on both synthetic and real images with the Jaccard similarity index. …

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K-Nn-Based Classification Of Sleep Apnea Types Using Ecg, Oğuz Han Ti̇muş, Emi̇ne Doğru Bolat Jan 2017

K-Nn-Based Classification Of Sleep Apnea Types Using Ecg, Oğuz Han Ti̇muş, Emi̇ne Doğru Bolat

Turkish Journal of Electrical Engineering and Computer Sciences

Obstructive sleep apnea syndrome (OSAS) is a common sleep disorder that yields cardiovascular diseases, excessive daytime sleepiness, and poor quality of life if not treated. Classification of OSAS from electrocardiograms (ECGs) is a noninvasive method and much more affordable than traditional methods. This study proposes a pattern recognition system for automated apnea diagnosis based on heart rate variability (HRV) and ECG-derived respiratory signals. The k-nearest neighbor (k-NN) classifier has been used to develop the models for classifying the sleep apnea types. For comparison purposes, classification models based on multilayer perceptron, support vector machines, and C4.5 decision tree (C4.5 DT) have …

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Fuzzy Support Vector Machine Based On Hyperbolas Optimized By The Quantum-Inspired Gravitational Search Algorithm, Feng Ni, Yuzhu He, Fei Jiang Jan 2017

Fuzzy Support Vector Machine Based On Hyperbolas Optimized By The Quantum-Inspired Gravitational Search Algorithm, Feng Ni, Yuzhu He, Fei Jiang

Turkish Journal of Electrical Engineering and Computer Sciences

Fuzzy support vector machines (FSVMs) are known for their excellent antinoise performance, but there is no general rule when the fuzzy membership function (FMF) is set up. A novel FSVM based on hyperbolas optimized by the quantum-inspired gravitational search algorithm (QGSH-FSVM) is proposed to handle this question. In the proposed QGSH-FSVM, the FMF is defined by two disparate hyperbolas, whose eccentricities are optimized by the quantum-inspired gravitational search algorithm. A variable called diversity, revealing the percentage of a sample in different classes, is proposed to distinguish outliers or noises from valid samples. Experimental results confirm that the QGSH-FSVM is able …

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Constrained Control Allocation For Nonlinear Systems With Actuator Failures Or Faults, Saman Ebrahimi Boukani, Mohammad Javad Khosrowjerdi, Roya Amjadifard Jan 2017

Constrained Control Allocation For Nonlinear Systems With Actuator Failures Or Faults, Saman Ebrahimi Boukani, Mohammad Javad Khosrowjerdi, Roya Amjadifard

Turkish Journal of Electrical Engineering and Computer Sciences

In this paper, a combination of dynamic constrained control allocation with terminal sliding mode control is proposed for a general class of overactuated nonlinear systems with actuator faults/failures. First, the terminal sliding mode control is designed to converge the system tracking error to zero in a finite-time. Then a control allocation strategy is developed and will be solved by a Lyapunov method, which leads to a dynamic update law with finite-time convergence. This strategy satisfies input limits and when faults/failures occur in some of the actuators, the control signals are automatically redistributed among the healthy actuators. Simulation results on a …

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Horizontal Directional Drilling Pilot Bore Simulation, Paulius Tervydis, Ruta Jankuniene Jan 2017

Horizontal Directional Drilling Pilot Bore Simulation, Paulius Tervydis, Ruta Jankuniene

Turkish Journal of Electrical Engineering and Computer Sciences

Various underground communications (water or gas supply systems, sewage, power lines) have been installed in recent years using trenchless technologies, i.e. horizontal directional drilling (HDD). This technique by its nature does not disturb the traffic and is environmentally friendly. One must be aware that, with HDD, pipeline building time is shortened. With respect to the above, HDD is especially effective in highly populated or industrial areas. However, it is necessary to ensure that HDD works, in order to prevent damage to installed underground facilities. The aim of this work is to propose a user-friendly and inexpensive simulation tool with required …

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Axial Flux Pm Bldc Motor Design Methodology And Comparison With A Radial Flux Pm Bldc Motor, Ertuğrul Yeşi̇lbağ, Yasemi̇n Ertuğrul, Lale Ergene Jan 2017

Axial Flux Pm Bldc Motor Design Methodology And Comparison With A Radial Flux Pm Bldc Motor, Ertuğrul Yeşi̇lbağ, Yasemi̇n Ertuğrul, Lale Ergene

Turkish Journal of Electrical Engineering and Computer Sciences

The aim of this paper is to develop a methodology to design an axial flux permanent magnet brushless direct current (AFPM) motor for a washing machine and compare the results with a conventional radial flux permanent magnet brushless direct current (RFPM) motor with the same power ratings. The AFPM motor is designed based on the maximum power density for an optimum inner-to-outer diameter ratio by using the reference RFPM motor constraints, such as the same rated torque at the rated speed. Both motors use the same materials in terms of lamination, permanent magnet, and conductor. They both use ferrite magnets; …

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Lossless Predictive Coding Of Electric Signal Waveforms, Krzysztof Duda Jan 2017

Lossless Predictive Coding Of Electric Signal Waveforms, Krzysztof Duda

Turkish Journal of Electrical Engineering and Computer Sciences

This paper describes a new predictive coding algorithm designed for lossless compression of electric signal waveforms. Prediction coefficients are obtained from the sinusoidal signal autoregressive model. Predictors for a single sinusoid and the sum of two and three sinusoids are considered. Integer-to-integer coding is obtained by the proper (i.e. reversible) quantization of computations. The proposed coding algorithm shows better performance than the commonly used 2nd order differences coding and linear prediction coding that is optimal in the least squares sense.

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A Reduced-Order Observer Based On Stator Flux Estimation With Straightforward Parameter Identification For Sensorless Control Of Dfigs, Rahim Ajabi Farshbaf, Mohammad Reza Azizian, Vahid Eslampanah Jan 2017

A Reduced-Order Observer Based On Stator Flux Estimation With Straightforward Parameter Identification For Sensorless Control Of Dfigs, Rahim Ajabi Farshbaf, Mohammad Reza Azizian, Vahid Eslampanah

Turkish Journal of Electrical Engineering and Computer Sciences

This paper presents a new reducer-order observer for sensorless control of doubly fed induction generators (DFIGs), based on the Luenberger algorithm. Stable operation of the suggested observer is also considered in the design guidelines. Stator flux is selected as the state variable for the observer and its estimation error is used to correct the observer operation. The gain matrix of the proposed observer is calculated on the basis of flux error dynamics. The adaptation mechanism of the proposed observer is selected based on an estimation of rotor currents. A proportional integrator (PI) block is used in the structure of the …

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Fault Location Determination For Transmission Lines With Different Series-Compensation Levels Using Transient Frequencies, Düzgün Akmaz, Mehmet Sali̇h Mami̇ş, Müslüm Arkan, Mehmet Emi̇n Tağluk Jan 2017

Fault Location Determination For Transmission Lines With Different Series-Compensation Levels Using Transient Frequencies, Düzgün Akmaz, Mehmet Sali̇h Mami̇ş, Müslüm Arkan, Mehmet Emi̇n Tağluk

Turkish Journal of Electrical Engineering and Computer Sciences

In this paper, based on the theory of traveling waves, the fault distances on long transmission lines with various series-compensation levels are determined using transient current and voltage frequencies. Transmission lines with series compensation are modeled using Alternative Transients Program software with frequency-dependent effects on the line included in the simulation. The transient current and voltage signals are obtained from the model. A fast Fourier transform is used for frequency-domain conversion and fault location is estimated from the frequencies of fault-generated harmonics in the transient spectrum. The algorithm is implemented in MATLAB. To investigate the effect of compensation on accuracy, …

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Robust Control For Line-Of-Sight Stabilization Of A Two-Axis Gimbal System, Mehmet Baskin, Mehmet Kemal Leblebi̇ci̇oğlu Jan 2017

Robust Control For Line-Of-Sight Stabilization Of A Two-Axis Gimbal System, Mehmet Baskin, Mehmet Kemal Leblebi̇ci̇oğlu

Turkish Journal of Electrical Engineering and Computer Sciences

Line-of-sight stabilization against various disturbances is an essential property of gimbaled imaging systems mounted on mobile platforms. In recent years, the importance of target detection from higher distances has increased. This has raised the need for better stabilization performance. For that reason, stabilization loops are designed such that they have higher gains and larger bandwidths. As these are required for good disturbance attenuation, sufficient loop stability is also needed. However, model uncertainties around structural resonances impose strict restrictions on sufficient loop stability. Therefore, to satisfy high stabilization performance in the presence of model uncertainties, robust control methods are required. In …

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Prognosis Of Muscular Dystrophy With Extrinsic And Intrinsic Descriptors Through Ensemble Learning, Sathyavikasini Kalimuthu, Vijaya Vijayakumar Jan 2017

Prognosis Of Muscular Dystrophy With Extrinsic And Intrinsic Descriptors Through Ensemble Learning, Sathyavikasini Kalimuthu, Vijaya Vijayakumar

Turkish Journal of Electrical Engineering and Computer Sciences

Muscular dystrophy is a neuromuscular disorder that impairs the functioning of the locomotive muscles. Large deletion and duplication mutations in the gene sequences pave the way for these muscular dystrophies. Any heritable change can be used as input in computational studies such as pattern and classification models. Mutated gene sequences are generated by adopting the positional cloning approach on the reference cDNA sequence with mutational information from the Human Gene Mutational Database (HGMD). The extrinsic and intrinsic descriptors of the mutated gene sequence are indispensable to identifying the disease. This work describes a computational approach of building a disease classification …

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Multiverse Optimized Fuzzy-Pid Controller With A Derivative Filter For Load Frequency Control Of Multisource Hydrothermal Power System, Amit Kumar, Sathans Suhag Jan 2017

Multiverse Optimized Fuzzy-Pid Controller With A Derivative Filter For Load Frequency Control Of Multisource Hydrothermal Power System, Amit Kumar, Sathans Suhag

Turkish Journal of Electrical Engineering and Computer Sciences

In this paper, a multiverse optimized (MVO) fuzzy PID controller with a derivative filter (fuzzy-PIDF) is proposed for the load frequency control (LFC) of a two-area multisource hydrothermal power system. The superiority of the MVO algorithm is demonstrated by comparing the system LFC performance with integral and fuzzy-PIDF controllers, both optimized using MVO, as well as some of the recent heuristic optimization techniques such as the ant lion optimizer, gray wolf optimizer, differential evolution, bacterial foraging optimization algorithm, and particle swarm optimization. To the best of the knowledge of the authors, the use of the MVO technique has not yet …

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Sample Group And Misplaced Atom Dictionary Learning For Face Recognition, Meng Wang, Zhengping Hu, Zhe Sun, Mei Zhu, Mei Sun Jan 2017

Sample Group And Misplaced Atom Dictionary Learning For Face Recognition, Meng Wang, Zhengping Hu, Zhe Sun, Mei Zhu, Mei Sun

Turkish Journal of Electrical Engineering and Computer Sciences

Latest research results have demonstrated the effectiveness of both sparse (or collaborative) representation and dictionary learning for problem solving in face recognition and other signal classification. Considering the fact that an informative dictionary helps a lot in sparse coding, a novel model that consists of group dictionary learning and high-quality joint kernel collaborative representation was proposed in this paper, where rich information from original and virtual space was mined and constructed as a sample group space to improve classification accuracy. Meanwhile, joint kernel collaborative representation with an $\ell_{2}$-regularization-based classifier was used to capture more nonlinear structure and minimize the time …

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Method Of Singular Integral Equations In Diffraction By Semi-Infinite Grating: $H$-Polarization Case, Mstislav Kaliberda, Leonid Lytvynenko, Sergey Pogarsky Jan 2017

Method Of Singular Integral Equations In Diffraction By Semi-Infinite Grating: $H$-Polarization Case, Mstislav Kaliberda, Leonid Lytvynenko, Sergey Pogarsky

Turkish Journal of Electrical Engineering and Computer Sciences

Diffraction of the $H$-polarized electromagnetic wave by a semi-infinite strip grating is considered. The scattered field is represented as a superposition of the field induced by the currents on the strips of an infinite periodic grating and the field induced by the correction current excited due to end of the grating. Singular integral equations with additional conditions for infinite and semi-infinite periodic gratings are obtained. The current on the strips and spectral function of scattered field are expressed in terms of the solution of these equations. Numerical results for the near and far fields distribution are represented.

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A Random Number Generator For Lightweight Authentication Protocols: Xorshiftr+, Umut Can Çabuk, Ömer Aydin, Gökhan Dalkiliç Jan 2017

A Random Number Generator For Lightweight Authentication Protocols: Xorshiftr+, Umut Can Çabuk, Ömer Aydin, Gökhan Dalkiliç

Turkish Journal of Electrical Engineering and Computer Sciences

This paper presents the results of research that aims to find a suitable, reliable, and lightweight pseudorandom number generator for constrained devices used in the Internet of things. Within the study, three reduced versions of the xorshift+ generator are built. They are tested using the TestU01 suite as well as the NIST suite to measure their ability to produce randomness and performance values along with some other existing generators. The best of our reduced variations according to our tests, called the xorshiftR+, demonstrated great suitability for lightweight devices considering its randomness, performance, and resource usage.

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On The Design Of Equal Division Single-Band Filtering Dividers With An Extended Transmission Line And Resistor As Isolation Elements, Zafar Bedar Khan, Huiling Zhao Jan 2017

On The Design Of Equal Division Single-Band Filtering Dividers With An Extended Transmission Line And Resistor As Isolation Elements, Zafar Bedar Khan, Huiling Zhao

Turkish Journal of Electrical Engineering and Computer Sciences

This paper introduces a new scheme for effective output port isolation and return loss in RF-filtering divider design. The proposed design incorporates an extended transmission line and a conventional resistor as isolation elements. The technique has a simpler microstrip circuit implementation when it comes to the integration of a single-band band-pass filter with a Wilkinson power divider to achieve simultaneous filtering-dividing action. It is established that if a band-pass filter with a certain fractional-bandwidth is matched to 70.7 $\Omega $, a transmission line section and isolation resistor are sufficient for achieving reasonable output port return loss and isolation in the …

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Development Of Metal Oxide Arrester Block Using A Rare Earth Element For Very Fast Transient Overvoltage Applications, Kannadasan Raju, Valsalal Prasad, Jayavel Ramasamy Jan 2017

Development Of Metal Oxide Arrester Block Using A Rare Earth Element For Very Fast Transient Overvoltage Applications, Kannadasan Raju, Valsalal Prasad, Jayavel Ramasamy

Turkish Journal of Electrical Engineering and Computer Sciences

The protection ability of metal oxide arresters against switching, lightning, and steep current surges has been well proven. On the contrary, during the invasion of very fast transients, the existing arrester fails to operate due to delay in its initial response. In order to decrease the delay, it is imperative to improve the electrical properties of the arrester such as nonlinearity and voltage gradient with reduced capacitive effect. In this context, new arrester blocks are developed with the addition of a rare earth element, namely scandium trioxide (Sc$_{2}$O$_{3})$, and then sintered with a microwave sintering process. Owing to the uniform …

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Geospatial Drivers Of The Groundwater Δ18o Isoscape In A Temperate Maritime Climate (Republic Of Ireland), S. Regan, R. Goodhue, O. Naughton, Paul Hynds Jan 2017

Geospatial Drivers Of The Groundwater Δ18o Isoscape In A Temperate Maritime Climate (Republic Of Ireland), S. Regan, R. Goodhue, O. Naughton, Paul Hynds

Articles

In recent years, the concept of “isoscapes” has been used to describe spatiotemporal stable isotope distributions within natural environments including groundwater systems at multiple scales. This study presents an updated groundwater δ18O isoscape for the Republic of Ireland and describes the climatic and geological drivers influencing 18O composition. In all, 142 geographically and geologically representative groundwater installations were sampled and analysed, in addition to 35 samples from six nested boreholes. Geospatially, Irish groundwater exhibits high δ18O values in southern and western coastal regions, becoming progressively depleted inland before reaching lowest measured values along the eastern coast, equating to a national …

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An Iterative Bézier Method For Fitting Beta-Sheet Component Of A Cryo-Em Density Map, Michael Poteat, Jing He Jan 2017

An Iterative Bézier Method For Fitting Beta-Sheet Component Of A Cryo-Em Density Map, Michael Poteat, Jing He

Computer Science Faculty Publications

Cryo-electron microscopy (Cryo-EM) is a powerful technique to produce 3-dimensional density maps for large molecular complexes. Although many atomic structures have been solved from cryo-EM density maps, it is challenging to derive atomic structures when the resolution of density maps is not sufficiently high. Geometrical shape representation of secondary structural components in a medium-resolution density map enhances modeling of atomic structures. We compare two methods in producing surface representation of the β-sheet component of a density map. Given a 3-dimensional volume of β-sheet that is segmented from a density map, the performance of a polynomial fitting was compared with that …

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