Özdemir, Serpil
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Name Variants
Özdemir, Serpil
S.,Özdemir
S. Özdemir
Serpil, Özdemir
Ozdemir, Serpil
S.,Ozdemir
S. Ozdemir
Serpil, Ozdemir
Ozdemir, Nurten Karacan
Ozdemir, Salih C.
Özdemir, Aydoğan
Özdemir, Zeynep
Ozdemir, Mehmet Akif
S.,Özdemir
S. Özdemir
Serpil, Özdemir
Ozdemir, Serpil
S.,Ozdemir
S. Ozdemir
Serpil, Ozdemir
Ozdemir, Nurten Karacan
Ozdemir, Salih C.
Özdemir, Aydoğan
Özdemir, Zeynep
Ozdemir, Mehmet Akif
Job Title
Öğr. Gör.
Email Address
Serpıl.ozdemır@khas.edu.tr
ORCID ID
Scopus Author ID
Turkish CoHE Profile ID
Google Scholar ID
WoS Researcher ID
Scholarly Output
17
Articles
6
Citation Count
0
Supervised Theses
1
16 results
Scholarly Output Search Results
Now showing 1 - 10 of 16
Article Branch Outage Simulation Based Contingency Screening by Gravitational Search Algorithm(Praise Worthy Prize Srl, 2012) Ceylan, Oğuzhan; Ceylan, Oğuzhan; Özdemir, Aydoğan; Dağ, Hasan; Dağ, Hasan; Özdemir, SerpilPower 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 optimization problem representing the branch outage phenomena is solved by the gravitational search algorithm. The proposed method is applied to IEEE 14 30 57 and 118 Bus Test systems and its performance from the point of capturing violations is evaluated. In addition false alarms and the computational accuracy of the proposed method are also analyzed by using scattering diagrams. Finally the proposed gravitational search based contingency screening is compared with full AC load flow solutions from the point of computational speed. Copyright (C) 2012 Praise Worthy Prize S.r.l. - All rights reserved.Conference Object Impacts of Load and Generation Volatilities on the Voltage Profiles Improved by Distributed Energy Resources(Institute of Electrical and Electronics Engineers Inc., 2020) Ahmedi, Bahman; Ceylan, Oğuzhan; Ceylan, Oğuzhan; Özdemir, Serpil; Özdemir, AydoğanWeather-dependent distributed renewable energy sources such as photovoltaics (PVs) and wind turbines (WT) are increasingly being connected to distribution networks (DNs). Increased penetration of these intermittent sources brought the necessity of using energy storage systems (ESSs) to achieve the intended benefits. This study presents an optimization process to determine optimal numbers, sizes, locations and distributed energy resources (DERs) as well as to determine the optimal operating strategy of ESSs in a distribution network. The objective is to improve the voltage profile and to minimize the installation costs. The proposed multi-objective formulation problem is solved by using ant lion multi-objective optimization algorithm. At the second part of the study, optimal values are tested with monthly extreme distributions and the impacts of load and distributed generation volatilies on the voltage profiles which were determined by Pareto-optimal solution candidates are analysed. Simulations were performed on 33 bus radial distribution system using Matlab. Finally the benefits obtained by the optimal solutions with less risk are compared.Article A Qualitative Study of Unveiling School Dropout Complexity in Türkiye(Springer, 2024) Özdemir, Serpil; Kemer, Fatma Nur Aras; Arslan, Arif; Tuna, BurakThis study investigates school dropout, particularly the shift to open high schools in Turkiye during the pandemic, through a multi-stakeholder lens. Using grounded theory, data was collected via semi-structured interviews with 12 students, 15 teachers, and 20 school administrators. Results reveal a model linking themes: predictive reasons for transferring to open high school, both pandemic-related and unrelated, positive/negative consequences of the transition, pandemic's impact on formal education continuity, essential open high school skills, and strategies to reduce such preferences. Findings highlight the sway of exam-focused education on open high school interest, regardless of COVID-19, and emphasize the need for equitable education amidst Turkiye's pandemic challenges. Theoretical implications may infer the necessity of approaching school dropout as a multilayered dynamic issue within the cultural context. The implications also may convey the significance of policies and systems not only to reduce the rates of school dropout but also critically unpack underlying reasons to make improvements.Conference Object Voltage Profile Improving and Peak Shaving Using Multi-Type Distributed Generators and Battery Energy Storage Systems in Distribution Networks(Institute of Electrical and Electronics Engineers Inc., 2020) Ahmedi, Bahman; Ceylan, Oğuzhan; Ceylan, Oğuzhan; Özdemir, Serpil; Özdemir, AydoğanOptimal sizing and siting of distributed generation (DG) units play an important role for improving voltage profile and reducing power losses. Moreover, battery energy storage system (BESS) units may help peak shaving. This paper presents a two stage approach, first of which aims optimal DG unit allocation, and second aims to determine optimal location and operation of BESS units. The problem formulation adopted due to the regulations in Turkey that supports DG units (Photovoltaics-PVs and Wind Turbines-WTs) with maximum unit size of 1 MW. A recently developed heuristic optimization method named as Harris hawks optimization (HHO) algorithm is used for obtaining near optimal solutions. We tested the developed model by using 33 and 141 bus distribution test systems.Conference Object Parallel Contingency Analysis Using Differential Evolution Based Solution for Branch Outage Problem(IEEE, 2010) Ceylan, Oğuzhan; Dağ, Hasan; Dağ, Hasan; Ceylan, Oğuzhan; Özdemir, Aydoğan; Özdemir, SerpilContingency 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 by differential evolution method. Using Matlab's parallel computing toolbox contingency analysis for IEEE 300 test system is performed and the results are presented. The study shows that it is straight forward to implement contingency analysis on the Matlab's parallel environment and obtain near linear speedups.Conference Object A Load Adaptive Cascade Pi Controller for Buck Converters Operating in Wide Load Range in Cathodic Protection Systems(IEEE, 2021) Ozdemir, Mehmet Akif; Aydemir, Mehmet Timur; Simsek, Oguz; Özdemir, Serpil; Aydemir, Mehmet TimurThis paper proposes a simple cascade PI controller for Buck converter to be used in impressed current cathodic protection (ICCP) systems which aim to operate in wide voltage and current ranges for any load condition. The Buck converter with cascade controller structure is a frequently used topology in ICCP systems to prevent buried steel pipelines from corrosion. Changes in the environment in which the pipe is embedded force the converter to operate at wide load and voltage ranges. However, in average current mode controllers, the gain of the current loop varies significantly with the load. At light loads, the inner current loop slows down dramatically and may stay behind the outer voltage loop. In order to solve these issues and to maintain the regulation of the pipeline voltage and the average load current, this paper presents a simple cascade PI controller whose coefficients are adapted to the changing load. The small signal analysis of the Buck converter in both continuous conduction mode (CCM) and discontinuous conduction mode (DCM) is performed and variables determining the transfer characteristics are examined. For the proposed controller, a design criteria based on circuit parameters have been established. With the parameters obtained by the proposed method, a sample cascade controller is designed and compared with classical PI controller in simulation. Also, a digitally controlled 100-W converter prototype is built to validate the performance.Book Part Comparison of Post Outage Bus Voltage Magnitudes Estimated by Harmony Search and Differential Evolution Methods(2009) Ceylan, Oğuzhan; Ceylan, Oğuzhan; Özdemir, Aydoğan; Dağ, Hasan; Dağ, Hasan; Özdemir, SerpilContingency studies are indispensable tools of both the power system planning and operational studies. Real time implementation of operational problems makes necessary the use of high speed computational methods while requiring reasonable accuracies. On the other hand, accuracy of the results and the speed of calculation depend on branch outage modeling as well as solution algorithm used. This paper presents a comparison of post outage bus voltage magnitudes calculated by two meta-heuristic approaches; namely differential evolution (DE) and harmony search (HS) methods. The methods are tested on IEEE 14, IEEE 30, IEEE 57, and IEEE 118 bus test systems and the results are compared both in terms of accuracy and calculation speed.Conference Object Towards Faster Branch Outage Simulations Using Simulated Annealing and Parallel Programming(IEEE, 2009) Ceylan, Oğuzhan; Dağ, Hasan; Özdemir, Aydoğan; Ceylan, Oğuzhan; Dağ, Hasan; Özdemir, SerpilContingency 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 estimation of an electrical power system. Real time implementation of the problem brings the necessity of using high speed methods while providing a reasonable accuracy. This paper presents simulated annealing based solution of the branch outage event which is formulated as a local optimization problem. To speed up the solution procedure the distributed computing toolbox of Matlab is used as a parallel programming tool. The results of the proposed method are compared to those of full AC method and are discussed both from the point of accuracy and solution speed.Conference Object Grey Wolf Optimizer for Allocation and Sizing of Distributed Renewable Generation(Institute of Electrical and Electronics Engineers Inc., 2019) Ahmadi, Bahman; Ceylan, Oğuzhan; Ceylan, Oğuzhan; Özdemir, Serpil; Özdemir, AydoğanIncreasing penetration of distributed energy resources (DERs) have brought operational and control philosophy changes in Smart Grids (SGs). Renewable energy based technologies are becoming more important due to their economic and environmental impacts. Distributed generations (DGs) in the form of small renewable energy resources such as solar photovoltaics (PVs) and Wind Turbines (WTs) are connected in radial distribution networks near to the loads. This paper presents optimal siting and sizing of distributed renewable energy resource to maintain voltage magnitude profiles. Bus voltage magnitude differences for each hour in a day of a distribution system are formulated as an objective function. Three consecutive days are taken into account representing the three seasons of a year. A new nature inspired algorithm Grey Wolf Optimizer (GWO) is used as a solution tool. The proposed formulation is applied to 33 bus and 69 bus radial distribution networks. MATLAB simulations are performed to validate the performance of the approach. Simulation results are discussed and compared with of the several available ones'.Article Antifungal Screening and in Silico Mechanistic Studies of an In-House Azole Library(2019) Sarı, Suat; Özdemir, Serpil; Kart, Didem; Sabuncuoğlu, Suna; Doğan, İnci Selin; Özdemir, Zeynep; Bozbey, İrem; Gencel, Melis; Eşsiz, Şebnem; Reynisson, Jóhannes; Karakurt, Arzu; Saraç, Selma; Dalkara, SevimSystemic Candida infections pose a serious public health problem with high morbidity and mortality. C. albicans is the major pathogen identified in candidiasis; however, non-albicans Candida spp. with antifungal resistance are now more prevalent. Azoles are first-choice antifungal drugs for candidiasis; however, they are ineffective for certain infections caused by the resistant strains. Azoles block ergosterol synthesis by inhibiting fungal CYP51, which leads to disruption of fungal membrane permeability. In this study, we screened for antifungal activity of an in-house azole library of 65 compounds to identify hit matter followed by a molecular modeling study for their CYP51 inhibition mechanism. Antifungal susceptibility tests against standard Candida spp. including C. albicans revealed derivatives 12 and 13 as highly active. Furthermore, they showed potent antibiofilm activity as well as neglectable cytotoxicity in a mouse fibroblast assay. According to molecular docking studies, 12 and 13 have the necessary binding characteristics for effective inhibition of CYP51. Finally, molecular dynamics simulations of the C. albicans CYP51 (CACYP51) homology model's catalytic site complexed with 13 were stable demonstrating excellent binding.
