Now showing items 21-40 of 60

  • Feature Extraction Based on Deep Learning for Some Traditional Machine Learning Methods 

    Deep learning is a subfield of machine learning and deep neural architectures can extract high level features automatically without handcraft feature engineering unlike traditional machine learning algorithms. In this paper, we propose a method, which combines feature extraction layers of a convolutional neural network with traditional machine learning algorithms, such as, support vector machine, gradient boosting machines, and random forest. All of the proposed hybrid models and the above mentioned ...

  • Gravitational search algorithm for post-outage bus voltage magnitude calculations 

    Authors:Ceylan, Oǧuzhan; Ozdemir, Aydogan; Daǧ, Hasan
    Publisher and Date:(2010)
    Branch outage problem is one of the key problems in power system security analysis. This paper solves branch outage problem using a bounded approach. Local constrained optimization problem in the bounded approach is solved by the gravitational search algorithm. Test results of IEEE 14 30 and 118 bus systems are compared to those of ac load flow method in terms of both accuracy and speed.

  • Harmony search method based parallel contingency analysis 

    Authors:Ceylan, Oǧuzhan; Daǧ, Hasan; Ozdemir, Aydogan
    Publisher and Date:(2010)
    Power system security management is one of the key problems in power system analysis. Power system management center operators need to simulate contingencies as fast as possible and take the remedial actions in time. These contingency analyses comprise of the outages of the branches transformers and other power system components. This paper solves branch outage problem using a bounded approach. Harmony search method is used to solve the local constrained optimization problem of the bounded approach. ...

  • HeteroSim: Heterogeneous simulation framework 

    In order to arrange heterogeneous simulation executions it would be useful to have simulation tools that enable easy and fast creation of simulation sessions employing real-time software components beside simulation codes. Although there have been considerable amount of research activities in simulation community the current simulation tools are not sufficiently capable to support such a cooperation between components working in real-time and simulation-time. In this paper we propose a new approach ...

  • Heuristic Methods for Postoutage Voltage Magnitude Calculations 

    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 key aims of electrical energy providers. As a result electrical energy providers need to check in great detail the integrity of their power systems by performing regular contingency studies of the equipment involved. Among others line and transformer outage simulations constitute ...

  • The impact of text preprocessing on the prediction of review ratings 

    Authors:Işık, Muhittin; Daǧ, Hasan
    Publisher and Date:(Tubitak, 2020)
    With the increase of e-commerce platforms and online applications, businessmen are looking to have a rating and review system through which they can easily reveal the feelings of customers related to their products and services. It is undeniable from the statistics that online ratings and reviews attract new customers as well as increase sales by means of providing confidence, ratification, opinions, comparisons, merchant credibility, etc. Although considerable research has been devoted to the ...

  • Implementation of a SDN (Software defined network) 

    Improving resource efficiency enhancing network security and achieving simpler network management have become the main goals for networking in the previous years. To accomplish these ideas an efficient routing traffic monitoring access control and server load balancing systems need to be designed. However these objectives make the optimization and management of networks rather difficult. In this paper Software Defined Networks (SDN) an alternative way for creating an optimized network by taking ...

  • Importance of Data Preprocessing For Improving Classification Performance on CAC Data Set 

    Authors:Sayın, Kamran Emre
    Publisher and Date:(Kadir Has University, 2012)
    Data Mining usage in Health Sector increased much in this decade because of the need

  • Improving Item-Based Recommendation Accuracy with User's Preferences on Apache Mahout 

    Authors:Jabakji, Ammar; Daǧ, Hasan
    Publisher and Date:(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 to recommend items to the users. Although the user-based collaborative filtering approaches have been applied successfully in many different domains some serious challenges remain especially in regards to large e-commerce sites for recommender systems need to manage millions of ...

  • Konutların Günlük Elektrik Güç Tüketimi Tahmini İçin Uygun Model Seçimi 

    Authors:Çayır, Aykut; Daǧ, Hasan
    Publisher and Date:(Fırat Üniv. Fen Bilimleri Enst., 2018)
    Zamana bağlı değişim gösteren olayların modellenmesi zorlu bir veri analizi problemidir. Bu olaylardan biri olan elektrik güç tüketiminde ise veriden mevsimsel etki ve tatil günleri gibi örüntülerin öğrenilerek bir tüketim tahmin modelinin geliştirilebilmesi için klasik makine öğrenmesi ve derin öğrenme yöntemlerinden yararlanılmaktadır. Bu çalışmada, İngiltere’nin Londra şehrindeki belirli bir bölgede 30 farklı eve ait yaklaşık 3 yıllık elektrik güç tüketimi veri kümesi kullanılarak uygun bir ...

  • Machine learning model to predict an adult learner's decision to continue ESOL course 

    Authors:Dahman, Mohammed R.M.
    Publisher and Date:(Kadir Has University, 2019)
    This study investigated the ability of the demographic and the affective variables to predict the adult learners' decision to continue ESOL courser. 278 adult learners, enrolled on ESOL course at FLS institution in Istanbul, Turkey, participated in the study. The result showed that the continued or dropped out groups, demonstrated statistical differences in the demographic variable (the placement test score) with a magnitude of large effect size (.378). Additionally, the result showed the effect ...

  • Machine learning model to predict an adult learner's decision to continue ESOL course 

    Authors:Dahman, Mohammed R.; Daǧ, Hasan
    Publisher and Date:(Springer, 2019)
    This study investigated the ability of the demographic and the affective variables to predict the adult learners' decision to continue ESOL courser. 278 adult learners, enrolled on ESOL course at FLS institution in Istanbul, Turkey, participated in the study. The result showed that the continued or dropped out groups, demonstrated statistical differences in the demographic variable (the placement test score) with a magnitude of large effect size (.378). Additionally, the result showed the effect ...

  • Methods to improve recommender systems in e-commerce and e-learning environments 

    Authors:Jabakji, Ammar
    Publisher and Date:(Kadir Has University, 2017)
    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 to recommend items to the users. Although the user-based collaborative filtering approaches have been applied successfully in many different domains some serious challenges remain especially in regards to large e-commerce sites for recommender systems need to manage millions of ...

  • Network science : a case of Bollywood 

    Authors:Yılmaz, Bahar
    Publisher and Date:(Kadir Has University, 2018)
    Bollywood is a regional movie industry that has made a name for itself globally. Over the years stars of Bollywood have amassed critical acclaim for their success. But what is Bollywood actually like as an industry? Are megastars like Shah Rukh Khan in fact as influential as they seem to be? The purpose of this study is to investigate Bollywood the movie industry in Mumbai india from a network perspective. Taking advantage of graph theory data science and network science a list of connections ...

  • On the selection of ınterpolation points for rational Krylov Methods 

    Authors:Yetkin, E. Fatih; Daǧ, Hasan
    Publisher and Date:(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 response of the transfer function are taken. These points correspond to the places where the sign of the numerical derivation of transfer function changes. The suggested method requires a set of linear system's solutions several times. But they can be computed concurrently by different ...

  • On-Line Transient Stability Assessment Using Matlab Parallel Programming Environment 

    Authors:Soykan, Gürkan; Daǧ, Hasan
    Publisher and Date:(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 costs of hardware and advanced package programs and techniques encourage researchers to apply parallel programming to the problems that are either too much time consuming or impossible to solve using serial computers. The real-time evaluation of TSA is now almost possible thanks ...

  • On-line transient stability assessment using Matlab parallel programming environment 

    Authors:Soykan, Gürkan; Daǧ, Hasan
    Publisher and Date:(IEEE, 2009)
    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 costs of hardware and advanced package programs and techniques encourage researchers to apply parallel programming to the problems that are either too much time consuming or impossible to solve using serial computers. The real-time evaluation of TSA is now almost possible thanks ...

  • Öykü anlatıcısı olarak karakter : tek kişilik bir destan uyarlamasında anlatıcı 

    Authors:Şahal, Süleyman
    Publisher and Date:(Kadir Has University, 2017)
    in credit scoring statistical methods like logistic regression have been successfully used for years. in the last two decades several data mining algorithms have gained popularity and proved themselves to be useful in credit scoring. Most recent studies indicate that data mining methods are indeed good predictors of default. Additionally ensemble models which combine single models have even better predictive capability. However in most studies the rationale behind data transformation steps and ...

  • Parallel contingency analysis using differential evolution based solution for branch outage problem 

    Authors:Ceylan, Oǧuzhan; Daǧ, Hasan; Ozdemir, Aydogan
    Publisher and Date:(IEEE, 2009)
    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 outages are within the acceptable limits the system is called secure. In this paper we solve the contingency problem using a recently developed local constrained optimization based branch outage problem. The optimization problem resulted from the formulation of branch outage is solved ...

  • Parallel Contingency Analysis Using Differential Evolution Based Solution For Branch Outage Problem 

    Authors:Ceylan, Oǧuzhan; Daǧ, Hasan; Özdemir, Aydoğan
    Publisher and Date:(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 outages are within the acceptable limits the system is called secure. In this paper we solve the contingency problem using a recently developed local constrained optimization based branch outage problem. The optimization problem resulted from the formulation of branch outage is solved ...