Behavior-Based Detection Of Application Layer Distributed Denial Of Service Attacks During Flash Events,
2016
TÜBİTAK
Behavior-Based Detection Of Application Layer Distributed Denial Of Service Attacks During Flash Events, Renukadevi Saravanan, Saraswathi Shanmuganathan, Yogesh Palanichamy
Turkish Journal of Electrical Engineering and Computer Sciences
Distributed denial of service (DDoS) attacks are ever threatening to the developers and users of the Internet. DDoS attacks targeted at the application layer are especially difficult to be detected since they mimic the legitimate users' requests. The situation becomes more serious when they occur during flash events. A more sophisticated algorithm is required to detect such attacks during a flash crowd. A few existing works make use of flow similarity for differentiating flash crowds and DDoS, but flow characteristics alone cannot be used for effective detection. In this paper, we propose a novel mechanism for discriminating DDoS and flash …
Small Signal Analysis For Dc Bus Voltage Disturbance Resistance Of Voltage Source Converter,
2016
TÜBİTAK
Small Signal Analysis For Dc Bus Voltage Disturbance Resistance Of Voltage Source Converter, Yingjie Wang, Xiaojie Wu, Ping Lu, Yonglei Zhang
Turkish Journal of Electrical Engineering and Computer Sciences
The DC bus voltage of the voltage source converter (VSC) is prone to large fluctuation and even to losing its stability for the large mutation of grid voltage or DC-link loads. First the characteristics of two-step transmission to power in the VSC are analyzed, proving that it is inevitable for DC bus voltage fluctuation to occur when grid voltage or DC-link loads mutate. A new two-step feedforward control strategy is then put forward for curbing the fluctuation, which overcomes the shortcoming by which the traditional feedforward control strategy is affected for the performance of current control. The small signal models …
Passivity-Based Robust Controller Design For A Variable Speed Wind Energy Conversion System,
2016
TÜBİTAK
Passivity-Based Robust Controller Design For A Variable Speed Wind Energy Conversion System, Peng Wang, Haisong Wang, Xu Cai, Zhengzhi Han
Turkish Journal of Electrical Engineering and Computer Sciences
This paper proposes a design method for a robust controller to improve the stability and system dynamic behavior for variable speed wind energy conversion systems. By analyzing the mathematical model of a wind power conversion system, control strategies for both a generator-side converter and a grid-side converter are given. For the generator-side converter, the well-known maximum power point tracking method is employed, while for the grid-side converter, a robust controller is presented based on passivity theory. The $L_{2}$-gain performance is analyzed using linear matrix inequality. Moreover, in order to accelerate the dynamic response and reduce the DC link voltage fluctuations, …
Chattering-Eliminated Adaptive Sliding-Mode Control: An Experimental Comparison Study,
2016
TÜBİTAK
Chattering-Eliminated Adaptive Sliding-Mode Control: An Experimental Comparison Study, Murat Furat, İlyas Eker
Turkish Journal of Electrical Engineering and Computer Sciences
The present paper deals with a new adaptive sliding-mode control. The switching and equivalent control laws include adaptive gains. An error-dependent adaptive gain in the switching control law and an adaptive parameter in the equivalent control law with respect to open-loop transient response of the system are proposed to eliminate chattering and to increase the performance of the controller. The proposed approach results in chattering elimination without using any complex calculation-based methods, which is highly useful for practical applications. The number of independent gains is also minimized. Therefore, tuning of those gains is simplified. The proposed controller is compared experimentally …
A Generalized Particle Swarm Optimization Using Reverse Direction Information,
2016
TÜBİTAK
A Generalized Particle Swarm Optimization Using Reverse Direction Information, Emre Çomak
Turkish Journal of Electrical Engineering and Computer Sciences
In this study, an improved particle swarm optimization (PSO) algorithm, including 4 types of new velocity updating formulae (each is equal to the traditional PSO), was introduced. This algorithm was called the reverse direction supported particle swarm optimization (RDS-PSO) algorithm. The RDS-PSO algorithm has the potential to extend the diversity and generalization of traditional PSO by regulating the reverse direction information adaptively. To implement this extension, 2 new constants were added to the velocity update equation of the traditional PSO, and these constants were regulated through 2 alternative procedures, i.e. max--min-based and cosine amplitude-based diversity-evaluating procedures. The 4 most commonly …
Solving Multimodal Optimization Problems Based On Efficient Partitioning Of Genotypic Search Space,
2016
TÜBİTAK
Solving Multimodal Optimization Problems Based On Efficient Partitioning Of Genotypic Search Space, Atabak Mashhadi Kashtiban, Sohrab Khanmohammadi, Kayvan Asghari
Turkish Journal of Electrical Engineering and Computer Sciences
Enhancing the exploration and exploitation of multimodal optimization is still an interesting and challenging problem in optimization. Here we present a new population-based evolutionary algorithm for multiple optimal determinations. The approach is simply based on partitioning the genotypic search space and running a simple genetic algorithm with a small population within each partition. To increase the efficiency of the algorithm, the first-order discrete derivative of the fitness function for elite solutions was used to omit extra solutions. If the derivative of the fitness function is larger than a specified gradient threshold, no optimum exists within a given partition, and no …
A Distributed Map Animation Framework For Spatiotemporal Datasets,
2016
TÜBİTAK
A Distributed Map Animation Framework For Spatiotemporal Datasets, Ahmet Sayar
Turkish Journal of Electrical Engineering and Computer Sciences
Maps are an excellent way to present data that have spatial components. However, when the data being presented vary over time, a simple two-dimensional map ignores an important feature of the data. An animated map that shows a series of two-dimensional maps at successive points in time allows one to add a time dimension to the display of data. The current study proposes a distributed service-oriented architecture to create map animations from spatiotemporal datasets. We extend the open standards GIS web services definitions with a topic-based publish-subscribe paradigm, which best suits the animation requirements. The effectiveness of the technique is …
Economic Assessment Of A Hybrid Turboexpander-Fuel Cell Gas Energy Extraction Plant,
2016
TÜBİTAK
Economic Assessment Of A Hybrid Turboexpander-Fuel Cell Gas Energy Extraction Plant, Ahmad Darabi, Ahmad Shariati, Reza Ghanaee, Ali Soleimani
Turkish Journal of Electrical Engineering and Computer Sciences
In this paper, a hybrid turboexpander-fuel cell (TE-FC) is investigated for extraction of electrical energy from high pressure gas in which the fuel cells are used for preheating the gas. Combination of expanders and fuel cells will reduce the fuel consumption and greenhouse gas emission. This study reveals that there are some circumstances in which the use of fuel cells in conjunction with a turboexpander is not recommended from an economic point of view. This paper seeks the region in which utilization of fuel cells along with a turboexpander presents maximum economic profit. Using the strategy provided in this paper …
An Improved Security Framework For Web Service-Based Resources,
2016
TÜBİTAK
An Improved Security Framework For Web Service-Based Resources, Wenbin Jiang, Hui Xu, Hao Dong, Hai Jin, Xiaofei Liao
Turkish Journal of Electrical Engineering and Computer Sciences
Web service-based application has become one of the dominative ones of the Internet. This trend brings more and more security challenges in reliability, confidentiality, and data nonrepudiation, especially in some systems that have massive diversified resources. An improved framework for secure accesses of Web resources is presented and implemented by extending and enhancing the Spring Security framework. It improves the security level of systems for identity authentication, authorized access, and secure transmission. The highly safe authentication is based on the integration of an improved authentication module of Spring Security with a U-key method and a RSA algorithm. For authorized access, …
Design Of A High-Linear, High-Precision Analog Multiplier, Free From Body Effect,
2016
TÜBİTAK
Design Of A High-Linear, High-Precision Analog Multiplier, Free From Body Effect, Ali Naderi Saatlo, İsmai̇l Serdar Özoğuz
Turkish Journal of Electrical Engineering and Computer Sciences
In this paper, a new CMOS four-quadrant analog multiplier circuit is proposed, based on a pair of dual-translinear loops. The significant features of the circuit are its high accuracy and high linearity as well as its body effect-free operation, owing to the fact that the circuit relies on a new dual-translinear topology. In addition, harmonic distortions are precisely discussed due to their conceivable mismatches, including transconductance and threshold voltage of the transistors. HSPICE postlayout simulation results are presented to verify the validity of the theoretical analysis, where under a supply voltage of 2.8 V, the bandwidth of the proposed multiplier …
Sizing Design And Implementation Of A Flywheel Energy Storage System For Space Applications,
2016
TÜBİTAK
Sizing Design And Implementation Of A Flywheel Energy Storage System For Space Applications, Kutlay Aydin, Mehmet Ti̇mur Aydemi̇r
Turkish Journal of Electrical Engineering and Computer Sciences
Flywheel energy storage systems have become an important research subject in recent years. They are also considered for space applications instead of hazardous and bulky electrochemical batteries. In this paper, a flywheel energy storage system has been designed for satellite attitude control systems. Power requirements of a small commercial satellite have been used as the starting point of the design. The designed system includes a BLDC motor. The machine is run as a motor for 60 min and the stored energy is discharged during the following 30 min to simulate low orbit satellite operation. Experimental results show that these systems …
Study Of Temperature Distribution In Light--Tissue Interaction Using The Fem,
2016
TÜBİTAK
Study Of Temperature Distribution In Light--Tissue Interaction Using The Fem, Ahmet Yasi̇n Çi̇tkaya, Şaban Seli̇m Şeker
Turkish Journal of Electrical Engineering and Computer Sciences
In this paper, the numerical modeling of interaction between light sources and living biological tissue is studied. One of the most important results of physical interactions of light with biological tissue are thermal changes, which are a consequence of absorption of light. The severity of the effects is dependent upon several factors, including exposure duration, wavelength of the beam, beam energy, tissue type, and the area that is exposed to the beam. The temperature response of tissue irradiation is governed by the extensively used Pennes bioheat equation in a 3-dimensional space. The Pennes equation is solved initially for a single-layer …
A Mapreduce-Based Distributed Svm Algorithm For Binary Classification,
2016
TÜBİTAK
A Mapreduce-Based Distributed Svm Algorithm For Binary Classification, Ferhat Özgür Çatak, Mehmet Erdal Balaban
Turkish Journal of Electrical Engineering and Computer Sciences
Although the support vector machine (SVM) algorithm has a high generalization property for classifying unseen examples after the training phase~and a small loss value, the algorithm is not suitable for real-life classification and regression problems. SVMs cannot solve hundreds of thousands of examples in a training dataset. In previous studies on distributed machine-learning algorithms, the SVM was trained in a costly and preconfigured computer environment. In this research, we present a MapReduce-based distributed parallel SVM training algorithm for binary classification problems. This work shows how to distribute optimization problems over cloud computing systems with the MapReduce technique. In the second …
Feature Selection For Movie Recommendation,
2016
TÜBİTAK
Feature Selection For Movie Recommendation, Zehra Çataltepe, Mahi̇ye Uluyağmur, Esengül Tayfur
Turkish Journal of Electrical Engineering and Computer Sciences
TV users have an abundance of different movies they could choose from, and with the quantity and quality of data available both on user behavior and content, better recommenders are possible. In this paper, we evaluate and combine different content-based and collaborative recommendation methods for a Turkish movie recommendation system. Our recommendation methods can make use of user behavior, different types of content features, and other users' behavior to predict movie ratings. We gather different types of data on movies, such as the description, actors, directors, year, and genre. We use natural language processing methods to convert the Turkish movie …
Common-Mode Emi Evaluation Of Forward Converter With Various Core-Reset Schemes,
2016
TÜBİTAK
Common-Mode Emi Evaluation Of Forward Converter With Various Core-Reset Schemes, Mohammad Rouhollah Yazdani, Nahid Amini Filabadi
Turkish Journal of Electrical Engineering and Computer Sciences
In switching power converters, electromagnetic emissions can interfere with the normal operation of the converter or other adjacent systems. Among various power converters, forward converters are widely used at low and medium powers that need a transformer core-reset scheme. In this paper, a prediction procedure for conducted common-mode EMI of a single-switch forward converter is presented, and common-mode EMI levels are predicted considering heat-sink parasitic capacitors and main PCB parasitic elements. The accuracy of prediction results is examined via experimental results. In addition, effects of conventional passive core-reset schemes on the conducted EMI are evaluated via experimental results. Along with …
Internet-Based Multiuser In-Circuit Emulator Design For 8051 Microprocessors,
2016
TÜBİTAK
Internet-Based Multiuser In-Circuit Emulator Design For 8051 Microprocessors, Kubi̇lay Taşdelen, Aki̇f Kutlu
Turkish Journal of Electrical Engineering and Computer Sciences
A real-time, Internet-based 8051 microprocessor in-circuit emulator (MicroLabICE) was designed and run for microprocessor lessons for undergraduate and graduate programs of electrical, electronics, communication, and computer engineering. Users can run applications developed for the 8051 microprocessor online on a physical circuit not being limited to a specific time or place with the 8051 microprocessor in-circuit emulator (ICE). The programs prepared by users are transferred to the controller area network (CAN) through an online server and program the ICE experiment module. Codes loaded on the designed emulator experiment module are run step by step and values that 8051 microprocessor registers have …
Statistical Learning Approaches In Diagnosing Patients With Nontraumatic Acute Abdomen,
2016
TÜBİTAK
Statistical Learning Approaches In Diagnosing Patients With Nontraumatic Acute Abdomen, Gökmen Zararsiz, Hizir Yakup Akyildiz, Di̇nçer Göksülük, Selçuk Korkmaz, Ahmet Öztürk
Turkish Journal of Electrical Engineering and Computer Sciences
A quick evaluation is required for patients with acute abdominal pain. It is crucial to differentiate between surgical and nonsurgical pathology. Practical and accurate tests are essential in this differentiation. Lately, D-dimer level has been found to be an important adjuvant in this diagnosis and obviously outperforms leukocyte count, which is widely used for diagnosis of certain cases. Here, we handle this problem from a statistical perspective and combine the information from leukocyte count with D-dimer level to increase the diagnostic accuracy of nontraumatic acute abdomen. For this purpose, various statistical learning algorithms are considered and model performances are assessed …
A New Market-Based Approach For Daily Volt/Var Control Of Distribution Systems In The Presence Of Distributed Energy Resources Using Benders Decomposition Algorithm, Abouzar Samimi, Ahad Kazemi
Turkish Journal of Electrical Engineering and Computer Sciences
Distributed energy resources (DERs), if properly coordinated with other Volt/Var control (VVC) devices, could be incorporated in daily VVC problem. In this paper, a new 2-stage model is presented for daily VVC of distribution systems including DERs, taking into account environmental and economic aspects. First, in the day-ahead market, an initial environmental-economic dispatch is performed to minimize both the electrical energy costs and the gas emissions pertaining to generation units. The initial scheduling results determined by the market operator are delivered to the second stage, namely the daily optimal dispatches of VVC devices, to examine them from operational viewpoints and …
A Conceptual Implementation Of A Buck Converter For An Off-Grid Hybrid System Consisting Of Solar And Wind Turbine Sources,
2016
TÜBİTAK
A Conceptual Implementation Of A Buck Converter For An Off-Grid Hybrid System Consisting Of Solar And Wind Turbine Sources, Ahmad Shukri Fazil Rahman, Abdul Rahim Abdul Razak, Syed Idris Syed Hassan
Turkish Journal of Electrical Engineering and Computer Sciences
A hybrid renewable power generation system is proposed through parallel connection between two potential energy resources: photovoltaic (PV) and wind turbines. The method consists of incorporating a buck converter connected by a wind turbine to provide adjustment according to PV potential. Unlike the conventional buck-boost converter topology that is normally used, this research tries to emphasize the use of a buck converter as part of the system configuration. Design schemes were carefully performed and the postdesign system was tested through system simulation with MATLAB/Simulink software. The simulated system offers promising and significant results, thus making it suitable for hardware implementation.
Adaptive Speed Observer With Disturbance Torque Compensation For Sensorless Induction Motor Drives Using Rt-Lab,
2016
TÜBİTAK
Adaptive Speed Observer With Disturbance Torque Compensation For Sensorless Induction Motor Drives Using Rt-Lab, Mohan Krishna, Febin Daya
Turkish Journal of Electrical Engineering and Computer Sciences
This paper presents an improved version of the extended Luenberger observer with joint estimation of rotor speed and disturbance torque. The mechanical model of the induction motor is also utilized for the estimation of disturbance torque to add to the robustness of the observer. The estimated disturbance torque is treated as a model disturbance and physically incorporated into the observer state dynamic equation. The dynamic performance and efficacy of the modified observer is tested for variations in external load and inertia coefficient in the mechanical model. The above observer model is first built offline, using MATLAB/Simulink block sets, and simulated. …
