WoS İndeksli Yayınlar Koleksiyonu by Institution Author "Dağ, Hasan"
Now showing items 1-16 of 16
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Applications of Eigenvalue Counting and Inclusion Theorems in Model Order Reduction
Yetkin, E. Fatih; Dağ, Hasan (Springer-Verlag Berlin, 2010)We suggest a simple and an efficient iterative method based on both the Gerschgorin eigenvalue inclusion theorem and the deflation methods to compute a Reduced Order Model (ROM) to lower greatly the order of a given state ... -
Branch outage simulation based contingency screening by gravitational search algorithm
Ceylan, Oğuzhan; Özdemir, Aydoğan; Dağ, Hasan (Praise Worthy Prize Srl, 2012)Power systems contingency analysis is an important issue for electric power system operators. This paper performs branch outage simulation based contingency screening using a bounded network approach. Local constrained ... -
Distributed Memory Parallel Transient Stability Analysis on a PC Cluster with Ethernet
Soykan, Gürkan; Flueck, Alexander J.; Dağ, Hasan (Praise Worthy Prize Srl, 2010)On-line transient stability analysis is a necessity for real-time power system control and security. Parallel processing is a natural technology for achieving real-time solution performance. This paper presents a ... -
Double branch outage modeling and simulation: Bounded network approach
Ceylan, Oğuzhan; Özdemir, Aydoğan; Dağ, Hasan (Elsevier Science, 2015)Energy management system operators perform regular outage simulations in order to ensure secure operation of power systems. AC power flow based outage simulations are not preferred because of insufficient computational ... -
A Generic Framework for Building Heterogeneous Simulations of Parallel and Distributed Computing Systems
Dursun, Taner; Dağ, Hasan (Springer Heidelberg, 2017)There have been many systems available for parallel and distributed computing (PDC) applications such as grids clusters super-computers clouds peer-to-peer and volunteer computing systems. High-performance computing (HPC) ... -
Heuristic Methods for Postoutage Voltage Magnitude Calculations
Ceylan, Oğuzhan; Özdemir, Aydogan; Dağ, Hasan (TUBITAK Scientific & Technical Research Council Turkey, 2016)Power systems play a significant role in every aspect of our daily lives. Hence their continuation without any interruption (or with the least duration of interruption due to faults or scheduled maintenances) is one of the ... -
Improving Item-Based Recommendation Accuracy with User's Preferences on Apache Mahout
Jabakji, Ammar; Dağ, Hasan (IEEE, 2016)Recommendation systems play a critical role in the Information Science application domain especially in e-commerce ecosystems. In almost all recommender systems statistical methods and machine learning techniques are used ... -
A New Preconditioner Design Based on Spectral Division for Power Flow Analysis
Dağ, Hasan; Yetkin, E. Fatih; Manguoglu, Murat (Praise Worthy Prize Srl, 2011)Solution of large sparse linear systems is the most lime consuming part in many power system simulations. Direct solvers based on LU factorization although robust are known to have limited satiability on parallel platforms. ... -
On the selection of ınterpolation points for rational Krylov Methods
Yetkin, E. Fatih; Dağ, Hasan (Springer-Verlag Berlin, 2012)We suggest a simple and an efficient way of selecting a suitable set of interpolation points for the well-known rational Krylov based model order reduction techniques. To do this some sampling points from the frequency ... -
On-Line Transient Stability Assessment Using Matlab Parallel Programming Environment
Soykan, Gürkan; Dağ, Hasan (IEEE, 2010)Transient Stability Assessment (TSA) is the major part of Dynamic Security Assessment (DSA) in an electric power system. On-line TSA has gained more importance for power system security in last two decades. The decreasing ... -
Parallel Contingency Analysis Using Differential Evolution Based Solution For Branch Outage Problem
Ceylan, Oğuzhan; Dağ, Hasan; Özdemir, Aydoğan (IEEE, 2010)Contingency analysis is one of the most fundamental work an electricity management center operator has to perform regularly. If both bus voltage magnitudes and reactive power flowing on the branches during any type of ... -
Parallel Implementation Of Iterative Rational Krylov Methods For Model Order Reduction
Yetkin, E. Fatih; Dağ, Hasan (IEEE, 2010)Model order reduction (MOR) techniques are getting more important in large scale computational tasks like large scale electronic circuit simulations. In this paper we present some experimental work on multiprocessor systems ... -
A Recommender Model Based on Trust Value and Time Decay Improve the Quality of Product Rating Score in E-commerce Platforms
Işık, Muhittin; Dağ, Hasan (IEEE, 2017)Most of the existing products rating score algorithms do not take fake accounts and time decay of users' ratings into account when creating the list of recommendations. The trust values and the time decay of users' ratings ... -
Sparsity Preserving Computation for Spectral Projectors
Yetkin, E. Fatih; Dağ, Hasan (Amer Inst Physics, 2011)Several areas of applications such as model order reduction preconditioner design and eigenvalue problems for spectral projectors can be found in the literature. In this paper a fast and sparsity preserving approach for ... -
A sparsity-preserving spectral preconditioner for power flow analysis
Yetkin, Emrullah Fatih; Dağ, Hasan (TUBITAK Scientific & Technical Research Council Turkey, 2016)Due to the ever-increasing demand for more detailed and accurate power system simulations the dimensions of mathematical models increase. Although the traditional direct linear equation solvers based on LU factorization ... -
Towards Faster Branch Outage Simulations Using Simulated Annealing and Parallel Programming
Ceylan, Oğuzhan; Özdemir, Aydoğan; Dağ, Hasan (IEEE, 2009)Contingency studies such as branch outage and generator outage are among important studies of energy management centers operations. Branch outage modeling on the other hand is one of the basic steps of post-outage state ...