Impact Of The Primary User On The Secondary User Blocking Probability In Cognitive Radio Sensor Networks,
2019
TÜBİTAK
Impact Of The Primary User On The Secondary User Blocking Probability In Cognitive Radio Sensor Networks, Mohammad Mehdi Hassani, Reza Berangi
Turkish Journal of Electrical Engineering and Computer Sciences
With the increasing usage of wireless sensor network technologies, their unlicensed bands become overcrowded. To address this challenge, cognitive radio technology with the dynamic spectrum access policy has merged with Wireless Sensor Network to overcome spectrum underutilization. The Cognitive Radio Sensor Network (CRSN) has emerged as a promising solution to overcome spectrum scarcity in a resource-constrained wireless sensor network. In CRSN, TCP has to cope with a new type of packet loss due to the primary users (PU) arrival, known here as a secondary user (SU) blocking loss. In this paper SU blocking loss is modelled by a discrete-time Markov …
A Distributed Measurement Architecture For Inferring Tcp Round-Trip Times Through Passive Measurements,
2019
TÜBİTAK
A Distributed Measurement Architecture For Inferring Tcp Round-Trip Times Through Passive Measurements, Fatih Abut
Turkish Journal of Electrical Engineering and Computer Sciences
The round-trip time (RTT), defined as the time elapsed for transmission of a data packet to travel from one endpoint to the other and back again, is an important parameter for Internet quality. This paper proposes an extended version of the well-known SYN/ACK (SA) methodology for passively measuring the RTTs over Transmission Control Protocol (TCP) connections. Differently from the original version of the SA methodology and the rest of studies in the related literature, the proposed passive methodology measures not only the total RTT of an end-to-end connection but also the proportion of the existing connection sections on this entire …
Task Graph Scheduling In The Presence Of Performance Fluctuations Of Computational Resources,
2019
TÜBİTAK
Task Graph Scheduling In The Presence Of Performance Fluctuations Of Computational Resources, Najmeh Malakoutifar, Hassan Motallebi
Turkish Journal of Electrical Engineering and Computer Sciences
Most of the existing work in the area of task graph scheduling considers resources with fixed processing capacity. The algorithms in these works rely on an estimation of the execution times of tasks on different resources. However, in practice, due to fluctuations in performance of cloud resources, these algorithms have challenges in these environments. In this paper, we focus on the problem of fault-tolerant scheduling of task graphs in the presence of performance fluctuations of computational resources. With the aim of reducing the adverse impacts of both soft errors and resource performance degradations, we propose an opportunistic task replication scheme …
Line Independency-Based Network Modelling For Backward/Forward Load Flow Analysis Of Electrical Power Distribution Systems,
2019
TÜBİTAK
Line Independency-Based Network Modelling For Backward/Forward Load Flow Analysis Of Electrical Power Distribution Systems, Reyhaneh Taheri, Alimorad Khajezadeh, Mohammad Hossein Rezaeian Koochi, Abbas Sharifi Nasab Anari
Turkish Journal of Electrical Engineering and Computer Sciences
In this paper a straightforward method for line independency-based modelling of electrical power distribution systems is proposed. The proposed method can determine the backward and forward sweeping routes of distribution systems for calculating line currents and bus voltages. To do that, the method identifies the independent lines in consecutive steps. An independent line is a line in the distribution system whose current does not depend on the current of other lines in the system. The proposed line independency-based network modelling is required to be performed only once and prior to the load flow analysis. The output of the proposed method, …
Nvrh-Lut: A Nonvolatile Radiation-Hardened Hybrid Mtj/Cmos-Based Look-Up Table For Ultralow Power And Highly Reliable Fpga Designs, Vahid Jamshidi
Turkish Journal of Electrical Engineering and Computer Sciences
Complementary metal oxide semiconductor (CMOS) downscaling leads to various challenges, such as high leakage current and increase in radiation sensitivity. To solve such challenges, hybrid MTJ/CMOS technology-based design has been considered as a very promising approach thanks to the high speed, low power, good scalability, and full compatibility of magnetic tunnel junction (MTJ) devices with CMOS technology. One important application of MTJs is the efficient utilization in building nonvolatile look-up tables (NV-LUTs) used in reconfigurable logic. However, NV-LUTs face severe reliability issues in nanotechnology due to the increasing process variations, reduced supply voltage, and high energetic particle strike at sensitive …
Hypothesis-Based Vertex Shift Method For Embedding Secret Logos In The Geometric Features Of 3d Objects,
2019
TÜBİTAK
Hypothesis-Based Vertex Shift Method For Embedding Secret Logos In The Geometric Features Of 3d Objects, Arthy R, Mala K, Suresh Babu R
Turkish Journal of Electrical Engineering and Computer Sciences
A recent challenge in information technology is to protect secret data and preserve the ownership of a product. There are many duplicate products being released on a daily basis. Owners have a high risk in proving their products. Watermarking is a technique used to preserve ownership by hiding the owner's information in their products. The proposed hypothesis-based vertex shifting algorithm embeds 2D secret logos in 3D cover objects. The 3D objects are represented using vertices and facets. 3D watermarking faces various challenges and one among them is capacity. In this work, capacity is addressed by using a hypothesis-based vertex shift …
Empirical Model Development For The Estimation Of Clearness Index Using Meteorological Parameters,
2019
TÜBİTAK
Empirical Model Development For The Estimation Of Clearness Index Using Meteorological Parameters, Fakhar Alam, Saif Ur Rehman, Shafiqur Rehman, Muhammad Jahangir, Muhammad Shoaib, Imran Siddiqui, Intikhab Ulfat
Turkish Journal of Electrical Engineering and Computer Sciences
The clearness index is an indispensable parameter required for the design and analysis of solar energy systems. In the absence of measured values for a specific location, the clearness index can be estimated from other measured meteorological variables. In this study three meteorological parameters, sunshine hours, monthly mean values of the temperature difference ($\Delta$T), and cloudiness, are used to develop empirical models for the estimation of clearness index. The empirical models are developed for five major cities in Pakistan (Karachi, Multan, Lahore, Islamabad, and Quetta). For empirical model development, long-term data (1991 to 2010) of monthly average clearness index, sunshine …
Optimal Siting, Sizing, And Parameter Tuning Of Statcom And Sssc Using Mpso And Remote Coordination Of The Facts For Oscillation Damping Of Power Systems, James Garba Ambafi, Sunusi Sani Adamu
Turkish Journal of Electrical Engineering and Computer Sciences
In electromechanical oscillation damping within power system, power system stabilizers (PSSs) are often deployed. However, a PSS is less effective in damping interarea oscillation and is limited by changes in network configuration due to weak tie-lines and load variations. Consequently, this paper presents a wide-area coordination approach that damps interarea oscillations using FACTS devices and phasor measurement units. We selected a static synchronous compensator (STATCOM) and static series synchronous compensator (SSSC) for realistic power system interarea oscillation damping. The performance of the coordinated FACTS installed in a power system depends on their suitable locations, sizes, tuned parameters, and remote input …
An Optimized Harmonic Elimination Method Based On Synchronized Microcontroller Architecture,
2019
TÜBİTAK
An Optimized Harmonic Elimination Method Based On Synchronized Microcontroller Architecture, Vivek Gopinath, Meenu Nair, Jayanta Biswas, Mukti Barai
Turkish Journal of Electrical Engineering and Computer Sciences
This paper proposes an optimized synchronous PWM method for harmonic elimination in a quasi square wave inverter. The synchronized PWM method enables online harmonic computation and PWM pulse generation in a multitasking digital controller to eliminate lower order harmonics. The multitasking digital controller reduces the look-up table requirement and helps in realizing efficient implementation to eliminate dominant harmonics. This method offers a simple scalable solution for combined fifth and seventh harmonic elimination using two low-cost eight-bit PIC microcontrollers (PIC18F4550, PIC18F452). Experimental results are demonstrated for a single-phase three-level inverter. The proposed method achieves 90$\% $ reduction of fifth and seventh …
Computation Of Stability Regions For Load Frequency Control Systems Including Incommensurate Time Delays,
2019
TÜBİTAK
Computation Of Stability Regions For Load Frequency Control Systems Including Incommensurate Time Delays, Şahi̇n Sönmez
Turkish Journal of Electrical Engineering and Computer Sciences
This article studies the impact of incommensurate communication time delays on stability regions defined in proportional-integral (PI) controller parameter space for a two-area load frequency control (LFC) system. Distributed power generations and large power plants increase the complexity and control issues of interconnected power systems. In interconnected power systems, LFC systems need to have complex communication networks to exchange data between control center and geographically dispersed generations. The receiving/transmitting of remote measuring data through communication infrastructures causes inevitable time delays, which adversely affect controller performance and stability of the LFC system. Time delays introducing feedback control loops of a multiarea …
A Hybrid Multiband Printed Loop Antenna For Wlan/Wimax Bands For Applications In Mimo Systems,
2019
TÜBİTAK
A Hybrid Multiband Printed Loop Antenna For Wlan/Wimax Bands For Applications In Mimo Systems, Ali Shahshahani, Mohammad Amin Honarvar
Turkish Journal of Electrical Engineering and Computer Sciences
In this article a thin hybrid multiband printed loop antenna is presented for application in multiple-input multiple-output (MIMO) systems. The proposed antenna has several advantages; for example, the pseudofilter feature of the proposed antenna is one of this antenna's advantages. Because of the antenna's width ($9.5$~mm), it can be used on the edges of the board. The first resonant frequency is generated by the original loop of the antenna. Incorporation of different embedded components, i.e. a subsidiary loop, extended ground-traces, parasitic patch, and the slits, results in the proposed antenna resonating as a multiband antenna. This antenna is adjusted in …
Design And Control Of An Lcl-Type Single-Phase Grid-Connected Inverter With Inverter Current Feedback Using The Phase-Delay Method, Fati̇h Evran
Turkish Journal of Electrical Engineering and Computer Sciences
In this study, a novel single-phase grid-connected microinverter system and its control applications are introduced for solar energy systems. The proposed system consists of two stages to transfer solar power to the grid. In the first stage, an isolated high-gain DC/DC converter is used to increase low solar panel output voltage. In the second stage, an inverter is used to supply a sinusoidal current to the grid. Moreover, a proportional resonant controller is adopted to reduce grid current total harmonic distortions (THDs) and an LCL filter is used to provide better harmonic attenuation. However, the ratio between the sampling frequency …
A Novel Initial Rotor Position Alignment Method For Permanent Magnet Synchronous Motor Using Incremental Encoder,
2019
TÜBİTAK
A Novel Initial Rotor Position Alignment Method For Permanent Magnet Synchronous Motor Using Incremental Encoder, Si̇nan Yilmaz, Mehmet Ti̇mur Aydemi̇r
Turkish Journal of Electrical Engineering and Computer Sciences
This paper presents a new method for the alignment of the rotor of permanent magnet synchronous motors with the phase axis of the stator during start-up. Once the rotor alignment is achieved, the real rotor position angle can be measured by using an incremental encoder and this value can be used in the field oriented control of the motor. Typically, a current is forced into the q-axis. In the proposed method a current is formed in the d-axis instead. Rotor alignment with the phase axis is achieved without any sudden motion by using a PI controller in the current loop. …
A Two-Stage Power Converter Architecture With Maximum Power Extraction For Low-Power Energy Sources,
2019
TÜBİTAK
A Two-Stage Power Converter Architecture With Maximum Power Extraction For Low-Power Energy Sources, Ridvan Umaz
Turkish Journal of Electrical Engineering and Computer Sciences
A two-stage power converter with maximum power extraction for energy harvesting is presented. The power converter consists of two stages; a maximum power extraction stage (i.e. first stage) and a regulation stage (i.e. second stage). The first stage consists of a number of charge pumps connected in parallel to extract power from the energy source while the second stage steps up low input voltage level to a usable level for a load. Proposed converter operates as low as 0.3 V and the output up-converts to 3.3 V. The proposed converter is aimed to extract maximum power from either low-power energy …
Global Maximum Operating Point Tracking For Pv System Using Fast Convergence Firefly Algorithm,
2019
TÜBİTAK
Global Maximum Operating Point Tracking For Pv System Using Fast Convergence Firefly Algorithm, Madhusmita Mohanty, Sankar Selvakumar, Chandrasekaran Koodalsamy, Sishaj Pulikottil Simon
Turkish Journal of Electrical Engineering and Computer Sciences
Global maximum operating point (GMOP) tracking is an important requirement of solar photovoltaic (PV) systems under partial shading conditions (PSCs). Though the perturb and observe algorithm is simple and effective, it fails to recognize the GMOP. This paper explores the application of the firefly algorithm (FA) to the maximum power point tracking (MPPT) problem of PV systems. In order to determine the shortest path to reach the GMOP under various PSCs, a new fast convergence firefly algorithm (FA) is proposed. Additionally, the change in firefly position is limited to a maximum value identified based on the characteristics of the PSC. …
Quantification Of Resistive Wall Instability For Particle Accelerator Machines,
2019
TÜBİTAK
Quantification Of Resistive Wall Instability For Particle Accelerator Machines, Fati̇h Yaman
Turkish Journal of Electrical Engineering and Computer Sciences
The aim of this study is to quantify longitudinal resistive wall impedances, corresponding wake functions, and wake potentials for different accelerator machines of interest. Accurate calculations of wake potentials by particle-in-cell codes are extremely difficult for the investigated parameters; therefore, we use an analytical approach and consider large domains with fine discretization for the required numerical integrations. The semianalytical wake potential computations are benchmarked against numerical general purpose 2D/3D Maxwell solver software codes and a different analytical approach for a certain set of parameters. We report examples to illustrate limitations of wake potential estimations from coupling impedances, and computations for …
The Impact Of Demand Response Programs On Upfc Placement,
2019
TÜBİTAK
The Impact Of Demand Response Programs On Upfc Placement, Abbas Sharifi Nasab Anari, Mehdi Ehsan, Mahmud Fotuhi Firuzabad
Turkish Journal of Electrical Engineering and Computer Sciences
Demand response (DR) and flexible AC transmission system (FACTS) devices can be effectively used for congestion management in power transmission systems. However, demand response program (DRP) implementation can itself affect the optimum location of FACTS devices, which is one of the main issues in power system planning. This paper investigates the impact of DRPs on unified power flow controller (UPFC) placement. The harmony search algorithm is employed to determine the optimum locations and parameter setting of UPFC in a long-term framework. The optimization problem is solved with different objectives including generation and congestion cost reduction, as well as loss reduction. …
Predicting Co And Nox Emissions From Gas Turbines: Novel Data And A Benchmark Pems,
2019
TÜBİTAK
Predicting Co And Nox Emissions From Gas Turbines: Novel Data And A Benchmark Pems, Heysem Kaya, Pinar Tüfekci̇, Erdi̇nç Uzun
Turkish Journal of Electrical Engineering and Computer Sciences
Predictive emission monitoring systems (PEMS) are important tools for validation and backing up of costly continuous emission monitoring systems used in gas-turbine-based power plants. Their implementation relies on the availability of appropriate and ecologically valid data. In this paper, we introduce a novel PEMS dataset collected over five years from a gas turbine for the predictive modeling of the CO and NOx emissions. We analyze the data using a recent machine learning paradigm, and present useful insights about emission predictions. Furthermore, we present a benchmark experimental procedure for comparability of future works on the data
A New Approach For Wind Turbine Placement Problem Using Modified Differential Evolution Algorithm,
2019
TÜBİTAK
A New Approach For Wind Turbine Placement Problem Using Modified Differential Evolution Algorithm, Hüseyi̇n Hakli
Turkish Journal of Electrical Engineering and Computer Sciences
Energy use is increasing worldwide with industrialization and advancing technology. Following this increase, renewable energy resources are increasingly preferred to reduce the costs of energy production. Wind energy is preferred as a renewable energy resource because it is clean and safe. Wind turbines are used to meet the demand for wind energy. They are placed close to each other to generate higher amounts of energy. However, the wake effect problem arises in these types of layouts, and this hinders the turbines from producing the desired yield. A modified differential evolution (MDE) algorithm was proposed in this study to solve the …
Comparative Evaluation Of A-B-C And Stationary Frame Of Reference For Permanent Magnet Brushless Dc Motor Drive Applied For Generation Of Switching Pattern, Manish Trivedi, Ritesh Keshri
Turkish Journal of Electrical Engineering and Computer Sciences
This paper focuses on the evaluation of the operation of permanent magnet brushless DC (PM BLDC) motor through the control implemented in the natural reference frame (a-b-c frame) and the stationary reference frame ($\alpha-\beta$ frame). To a large extent, ripple-free torque and attainment of higher torque-speed characteristic depend on the gating pulses/switching patterns of the inverter employed. PM BLDC motor requires injection of the square wave current for the maximum torque per ampere, so the reference is required to be generated and tracked accordingly. The effectiveness of the strategies of pulse-width-modulation-based current control in the a-b-c plane and, the case …
