Lyapunov's Direct Method For Stabilization Of The Furuta Pendulum,
2012
TÜBİTAK
Lyapunov's Direct Method For Stabilization Of The Furuta Pendulum, Türker Türker, Haluk Görgün, Gali̇p Cansever
Turkish Journal of Electrical Engineering and Computer Sciences
This paper presents a novel stabilization result for the Furuta pendulum for a large region of attraction including almost all of the upper half plane. The solution is obtained via constructing a Lyapunov function after set of coordinate changes. Then, a set of differential equations are solved to achieve asymptotic stability which is proved in accordance with La Salle's invariance principle. The effectiveness of the proposed stabilization method is illustrated with simulation studies.
Energy Savings In Simultaneous Multi-Threaded Processors Through Dynamic Resizing Of Datapath Resources,
2012
TÜBİTAK
Energy Savings In Simultaneous Multi-Threaded Processors Through Dynamic Resizing Of Datapath Resources, Gürhan Küçük, Mi̇ne Mesta
Turkish Journal of Electrical Engineering and Computer Sciences
Nowadays, all the designers of systems from high-performance servers to battery-operated handheld devices aim for reliability, high-performance and longevity. Central within these aims the issue of processor power consumption is becoming increasingly important. In this study, we aim to adapt our already-proven method for single-threaded superscalar processors to simultaneous multi-threaded (SMT) processors for energy savings. The original method focused on resizing datapath resources according to the demands of running applications. To achieve this, the targeted resources are physically divided into multiple partitions, and turned on and off according to the needs of the applications. Since, the energy consumption of the …
An Improved Distributed Power-Control Scheme For Cellular Mobile Systems,
2012
TÜBİTAK
An Improved Distributed Power-Control Scheme For Cellular Mobile Systems, Hamid Farrokhi, Mostafa Rezayi
Turkish Journal of Electrical Engineering and Computer Sciences
In this paper, a new distributed power-control (DPC) scheme is suggested to improve convergence speed and system robustness against carrier-to-interference-ratio (CIR) estimation errors. To expedite the CIR balancing in our DPC scheme, an instability detection rule was used. As compared with Foschini's DPC (FDPC) method, numerical results indicated that the proposed algorithm achieves performance improvements in terms of outage probability as well as in the algorithm's convergence speed. More specifically, by appropriate selection of some parameters, the algorithm speed reduces from about 90 iterations in FDPC to 9 iterations in the proposed algorithm. The system robustness against CIR estimation errors …
Design Parameters And Uncertainty Bound Estimation Functions For Adaptive-Robust Control Of Robot Manipulators,
2012
TÜBİTAK
Design Parameters And Uncertainty Bound Estimation Functions For Adaptive-Robust Control Of Robot Manipulators, Recep Burkan
Turkish Journal of Electrical Engineering and Computer Sciences
In this paper, a parameter and uncertainty bound estimation functions for adaptive-robust control of robot manipulators are developed. A Lyapunov function is defined and parameters and uncertainty bound estimation functions are developed based on the Lyapunov function. Thus, stability of an uncertain system is guaranteed and uniform boundedness of the tracking error is achieved. As distinct from previous parameter and bound estimation laws, the parameters and uncertainty bounds are updated as a function of a combination of trigonometric function depending on robot parameters and tracking error. Based on the same Lyapunov function, a robust control law is also defined and …
A Comparative Study Of Blind And Nonblind Trainings In A Single-Carrier Wimax (Ieee 802.16-2004) Radio,
2012
TÜBİTAK
A Comparative Study Of Blind And Nonblind Trainings In A Single-Carrier Wimax (Ieee 802.16-2004) Radio, Ali̇ Özen
Turkish Journal of Electrical Engineering and Computer Sciences
Experimental and theoretical bit error rate performance evaluations of blind and nonblind training techniques are obtained by using a single-carrier WiMAX (IEEE 802.16-2004) radio for high-order quadrature amplitude modulation channels. Instead of using a certain type of channel profile, this study concentrates on true frequency-selective Rayleigh fading channels and also evaluates the fast fading scenario of Rayleigh channels in a real-time WiMAX radio environment around 3.5 GHz. The popular least mean squares (LMS) learning algorithm and constant modulus learning algorithm (CMA) are used as benchmarks in an investigation of nonblind and blind trainings, namely recursive least squares (RLS), modified-CMA, normalized-CMA, …
Load Sharing Based On Moving Roles In Multiagent Systems,
2012
TÜBİTAK
Load Sharing Based On Moving Roles In Multiagent Systems, Şebnem Bora, Ali̇ Murat Ti̇ryaki̇, Oğuz Di̇kenelli̇
Turkish Journal of Electrical Engineering and Computer Sciences
In this paper, we present a load-sharing approach based on the refactoring of agents. According to our approach, the role(s) that makes an agent overloaded is identified and transferred to less loaded agents. The excess workload of this heavily loaded agent is then transferred to the new agent. This approach defines a new agent, called the ``monitor agent,'' which monitors the workload of agents in the organization and decides about the refactoring of the agents. The monitor agent uses the platform ontology, which explicitly describes the components of the agent organization, including agents and their roles, plans, and workloads. This …
Fuzzy Logic Control For A Wind/Battery Renewable Energy Production System,
2012
TÜBİTAK
Fuzzy Logic Control For A Wind/Battery Renewable Energy Production System, Onur Özdal Mengi̇, İsmai̇l Hakki Altaş
Turkish Journal of Electrical Engineering and Computer Sciences
In this study, a designed proportional-integral (PI) controller and a fuzzy logic controller (FLC) that fix the voltage amplitude to a constant value of 380 V and 50 Hz for loads supplied from a wind/battery hybrid energy system are explained and compared. The quality of the power produced by the wind turbine is affected by the continuous and unpredictable variations of the wind speed. Therefore, voltage-stabilizing controllers must be integrated into the system in order to keep the voltage magnitude and frequency constant at the load terminals, which requires constant voltage and frequency. A fuzzy logic-based controller to be used …
Training Data Optimization For Anns Using Genetic Algorithms To Enhance Mppt Efficiency Of A Stand-Alone Pv System,
2012
TÜBİTAK
Training Data Optimization For Anns Using Genetic Algorithms To Enhance Mppt Efficiency Of A Stand-Alone Pv System, Ahmet Afşi̇n Kulaksiz, Ramazan Akkaya
Turkish Journal of Electrical Engineering and Computer Sciences
Maximum power point tracking (MPPT) algorithms are used to force photovoltaic (PV) modules to operate at their maximum power points for all environmental conditions. In artificial neural network (ANN)-based algorithms, the maximum power points are acquired by designing ANN models for PV modules. However, the parameters of PV modules are not always provided by the manufacturer and cannot be obtained readily by the user. Experimental measurements implemented in the overall PV system may be used to obtain the ANN dataset. One drawback of this method is that the generalization ability of the neural network usually degrades and some data reducing …
Discrete Particle Swarm Optimization For The Team Orienteering Problem,
2012
TÜBİTAK
Discrete Particle Swarm Optimization For The Team Orienteering Problem, Ai̇şe Zülal Şevkli̇, Fati̇h Erdoğan Sevi̇lgen
Turkish Journal of Electrical Engineering and Computer Sciences
In this paper, a novel discrete particle swarm optimization (PSO) algorithm is proposed to solve the team orienteering problem (TOP). Discrete evaluation is achieved by redefining all operators and operands used in PSO. To obtain better results, a strengthened PSO, which improves both exploration and exploitation during the search process, is employed. Our algorithm achieves the best known solutions in a short time compared to previous heuristics for the TOP.
Performance Analysis Of Wind Turbine-Driven Permanent Magnet Generator With Matrix Converter,
2012
TÜBİTAK
Performance Analysis Of Wind Turbine-Driven Permanent Magnet Generator With Matrix Converter, Ramasamy Bharanikumar, A Nirmal Kumar
Turkish Journal of Electrical Engineering and Computer Sciences
Wind energy, among all of the renewable energy sources, has made rapid developments and significant inroads in electrical power systems. With the increased use of wind energy conversion systems (WECSs), several technologies have been developed. Since WECSs are more cost competitive, the comparison of different wind generator systems is the need of the hour. Permanent magnet generators employing these technologies have some significant advantages over conventional generators, such as no need of excitation, low volume and weight, high precision, and deletion of the gearbox. A variable-speed WECS with a permanent magnet generator and a matrix converter is proposed in this …
Economic Analysis Of A Wind-Battery Hybrid System: An Application For A House In Gebze, Turkey, With Moderate Wind Energy Potential, Bahti̇yar Dursun, Ci̇han Gökçöl
Turkish Journal of Electrical Engineering and Computer Sciences
In this study, the energy demand of a house in Gebze, Turkey, is met by using wind energy as a primary energy source combined with rechargeable batteries. The wind-battery system is simulated by MATLAB while considering that energy continuity is maintained by using a sufficient number of batteries. A life-cycle cost analysis is carried out over a 20-year system lifetime because the operating time of the hybrid system is subject to the turbine life, usually assumed to be 20 years. The wind turbine generators considered are of various nominal powers, ranging from 0.6 to 450 kW. For each wind turbine, …
Short-Term Wind Speed Estimation Based On Weather Data,
2012
TÜBİTAK
Short-Term Wind Speed Estimation Based On Weather Data, Okan Özgönenel, David W.P. Thomas
Turkish Journal of Electrical Engineering and Computer Sciences
For accurate and efficient use of wind power, it is important to know the statistical characteristics, availability, diurnal variation, and prediction of wind speed. Prediction of wind power permits the scheduling of the connection or the disconnection of wind turbines to achieve optimal operating costs. In this paper, a simple and accurate method for predicting wind speed based on weather-sensitive data is presented. The proposed wind speed prediction system is cost-effective and only needs wind speed data at 40 m and weather data to forecast wind speeds at 50 m and 60 m for the current and next months. Hellman …
Compact Dual-Band Split-Ring Antenna For 2.4/5.2 Ghz Wlan Applications,
2012
TÜBİTAK
Compact Dual-Band Split-Ring Antenna For 2.4/5.2 Ghz Wlan Applications, Siddik Cumhur Başaran
Turkish Journal of Electrical Engineering and Computer Sciences
This paper presents a compact dual-band printed antenna for 2.4/5.2 GHz WLAN applications. The radiating elements of the proposed antenna are composed of rectangular split-ring elements and metallic loadings placed appropriately between the rings. The antenna size is very compact (22 \times 26 \times 1.6 mm), and it can be integrated easily with other RF front-end circuits. It is demonstrated that the proposed antenna can completely cover the required bandwidths of IEEE 802.11b (2.4-2.484 GHz) and IEEE 802.11a (5.15-5.35 GHz) with satisfactory radiation characteristics. Analysis and design of the proposed antenna was carried out with the Ansoft highfrequency structure simulator. …
Multiobjective Fet Modeling Using Particle Swarm Optimization Based On Scattering Parameters With Pareto Optimal Analysis,
2012
TÜBİTAK
Multiobjective Fet Modeling Using Particle Swarm Optimization Based On Scattering Parameters With Pareto Optimal Analysis, Fi̇li̇z Güneş, Ufuk Özkaya
Turkish Journal of Electrical Engineering and Computer Sciences
In this paper, design-oriented field effect transistor (FET) models are produced. For this purpose, FET modeling is put forward as a constrained, multiobjective optimization problem. Two novel methods for multiobjective optimization are employed: particle swarm optimization (PSO) uses the single-objective function, which gathers all of the objectives as aggregating functions; and the nondominated sorting genetic algorithm-II (NSGA-II) sorts all of the trade-off solutions on the Pareto frontiers. The PSO solution is compared with the Pareto optimum solutions in the biobjective plane and the success of the first method is verified. Furthermore, the resulting FET models are compared with similar FET …
A Procedure To Specify The Weighting Matrices For An Optimal Load-Frequency Controller,
2012
TÜBİTAK
A Procedure To Specify The Weighting Matrices For An Optimal Load-Frequency Controller, Silvio José Pinto Simões Mariano, Jose Álvaro Nunes Pombo, Maria Do Rosário Alves Calado, Luis António Fialho Marcelino Ferreira
Turkish Journal of Electrical Engineering and Computer Sciences
The linear quadratic optimal regulator is one of the most powerful techniques for designing multivariable control systems. The performance of the system is specified in terms of a cost, which is the integral of a weighted quadratic function of the system state and control inputs, that is to be minimized by the optimal controller. The components of the state cost weighting matrix, Q, and the control cost weighting matrix, R, are ours to choose in mathematically specifying the way we wish the system to perform. Changing these matrices, we can modify the transient behavior of the closed-loop system. This paper …
Joint Source-Channel Coding For Error Resilient Transmission Of Static 3d Models,
2012
TÜBİTAK
Joint Source-Channel Coding For Error Resilient Transmission Of Static 3d Models, Mehmet Oğuz Bi̇ci̇, Andrey Norkin, Gözde Akar
Turkish Journal of Electrical Engineering and Computer Sciences
In this paper, performance analysis of joint source-channel coding techniques for error-resilient transmission of three dimensional (3D) models are presented. In particular, packet based transmission scenarios are analyzed. The packet loss resilient methods are classified into two groups according to progressive compression schemes employed: Compressed Progressive Meshes (CPM) based methods and wavelet based methods. In the first group, layers of CPM algorithm are protected unequally by Forward Error Correction (FEC) using Reed Solomon (RS) codes. In the second group, embedded bitstream obtained from wavelet based coding is protected unequally with FEC as well. Both groups of methods are scalable with …
Adaptive Qos Scheduling In A Service-Oriented Grid Environment,
2012
TÜBİTAK
Adaptive Qos Scheduling In A Service-Oriented Grid Environment, Tan Fong Ang, Teck Chaw Ling, Keat Keong Phang
Turkish Journal of Electrical Engineering and Computer Sciences
The use of grid technology and web services for resource sharing has received tremendous attention in recent years. The merging of these 2 technologies is able to provide additional multiple types of services and functionalities. However, the problem of scheduling services to meet quality of service (QoS) requirements remains challenging. This paper proposes an adaptive QoS (AQoS) scheduling algorithm for service-oriented grid environments. AQoS uses benchmarking and curve-fitting based on historical records to estimate job length. Job length and users' QoS requirements are then used to make scheduling decisions. AQoS is able to maximize service availability, reliability, and resource utilization …
Investigating The Relation Between Optimum Guard Interval And Channel Delay Spread For A Mc-Cdma System,
2012
TÜBİTAK
Investigating The Relation Between Optimum Guard Interval And Channel Delay Spread For A Mc-Cdma System, Çeti̇n Kurnaz, Hülya Gökalp
Turkish Journal of Electrical Engineering and Computer Sciences
This paper demonstrates a novel approach to determining the optimum guard interval for a multicarrier code division multiple access (MC-CDMA) system. Analytical expressions for useful and interference power are derived as a basis for comparison. From these, an expression for the signal-to-noise ratio of a detected bit is derived and used to determine the optimum guard interval for a given channel profile and system parameters. In contrast to other works, we use channel models based on actual measurements and we highlight important differences from theoretical models to support our approach. From our results, we propose an empirical rule for optimum …
Reconfigurable Antenna Structure For Rfid System Applications Using Varactor-Loading Technique,
2012
TÜBİTAK
Reconfigurable Antenna Structure For Rfid System Applications Using Varactor-Loading Technique, Yusuf Sevi̇nç, Adnan Kaya
Turkish Journal of Electrical Engineering and Computer Sciences
A novel method is presented for electrically tuning the frequency of a compact radio-frequency identification (RFID) tag antenna. A tuning circuit, comprising a radio frequency (RF) switch and discrete passive components, was completely integrated into the antenna element, which is thus free of DC wires. The low-profile printed antennas were fabricated together with the layouts of the DC control circuits and other RF/baseband circuit footprints. A surface-mounted varactor was applied as a frequency-tuning element at the proper places of the meandered slots in the compact antenna. Prototype designs showed that the in-band frequency (return loss < 10 dB) was tunable from 2.4 GHz to 2.8 GHz when the bias voltage varied from 4 V to 7 V. The impact of the tuning circuit on the antenna's return loss and radiation pattern were experimentally studied through comparison with the performance of a reference antenna not incorporating the tuning circuit. The proposed frequency tuning concept can be extended to more complex compact structures as well as other types of antennas to give enhanced electrical performance.
Improved Square Properties Of Idea,
2012
TÜBİTAK
Improved Square Properties Of Idea, Mete Akgün, Hüseyi̇n Demi̇rci̇, Mahmut Şami̇l Sağiroğlu, Pinar Kavak
Turkish Journal of Electrical Engineering and Computer Sciences
Block cipher encryption algorithms generally process on word structures of fixed length such as 8 or 16-bits. IDEA is one of the most widely used block ciphers and operates on 16-bit words. Square analysis is a method that exploits the word structure of block ciphers. Some square distinguishers of IDEA are given in previous studies. The best attacks against IDEA use square-like techniques. In this paper, we focus on the square properties of the IDEA block cipher. We consider all fixed word combinations of the plaintext to investigate the structural behavior of the algorithm. We observe that the cipher can …
