Scopus İndeksli Yayınlar Koleksiyonu

Permanent URI for this collectionhttps://hdl.handle.net/20.500.12469/1248

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Citation - WoS: 6
Citation - Scopus: 6
Gamma-Robust electricity market equilibrium models with transmission and generation investments
(SPRINGER HEIDELBERG, 2021) Çelebi, Emre; Krebs, Vanessa; Schmidt, Martin
We consider uncertain robust electricity market equilibrium problems including transmission and generation investments. Electricity market equilibrium modeling has a long tradition but is, in most of the cases, applied in a deterministic setting in which all data of the model are known. Whereas there exist some literature on stochastic equilibrium problems, the field of robust equilibrium models is still in its infancy. We contribute to this new field of research by considering Gamma-robust electricity market equilibrium models on lossless DC networks with transmission and generation investments. We state the nominal market equilibrium problem as a mixed complementarity problem as well as its variational inequality and welfare optimization counterparts. For the latter, we then derive a Gamma-robust formulation and show that it is indeed the counterpart of a market equilibrium problem with robustified player problems. Finally, we present two case studies to gain insights into the general effects of robustification on electricity market models. In particular, our case studies reveal that the transmission system operator tends to act more risk-neutral in the robust setting, whereas generating firms clearly behave more risk-averse.
Citation - WoS: 1
A Serbian Princess in Ottoman Palace: Mileva Olivera Lazarevic
(Ahmet Yesevi University, 2017) Keskin, Mustafa Çağhan
Born as the daughter of the serbian Knez Lazar taken into the Ottoman palace marrying Bayezid I (The Thunderbolt) who gave her father's execution order became the slave of Timur (Tamerlane) after the Battle of Ankara and when set free turning back to her country Olivera had a life full of trauma and tragedies resembling a romantic adventure According to the serbian she was a hero who sacrificed herself for her country according to the Ottomans she was a bad woman who adapted Bayezid to alcohol and entertainment according to European orientalist myths she was a princess who was despised by barbarians to whom was taken captive. This study aims to reveal the image of Olivera reflected in the works of contemporary Ottoman Byzantine Serbian Timurid and European sources narratives and arts with a focus on the life story of Olivera who although was essentially a member of the Ottoman dynasty did not have any monographs about her in Turkey.
Citation - Scopus: 2
Detection of Multiple Primary Systems Using Daa Uwb-Irs
(IEEE, 2009) Erküçük, Serhat; Lampe, Lutz; Schober, Robert
Underlay ultra wideband (UWB) systems have to be able to detect the presence of primary systems operating in the same band for detect-and-avoid (DAA) operation. In this paper the performances of joint and independent detection of multiple primary systems are investigated assuming that the primary systems are potentially dependent (e.g. frequency division duplex uplink-downlink communications). Joint detection is performed based on generating the maximum a posteriori (MAP) decision variables at the receiver where some bias terms are used with these variables in order to achieve a desired trade-off between the detection and false alarm probabilities. Independent detection is performed based on the Neyman-Pearson (NP) test which optimizes system threshold values individually in order to achieve the best detection probability for a given false alarm probability value. When the two detection schemes are compared it is shown that the gain of joint detection depends on the joint system activity values and the considered receiver operating characteristic (ROC) region where the complementary ROC curves illustrate the trade-off between missdetection and false alarm probabilities.
Citation - WoS: 6
Citation - Scopus: 7
An Interactive Memetic Algorithm for Production and Manufacturing Problems Modelled as a Multi-Objective Travelling Salesman Problem
(Taylor & Francis Ltd, 2012) Samanlıoğlu, Funda; Ferrell, William G.; Kurz, M. E.
In this paper a preference-based interactive memetic random-key genetic algorithm (PIMRKGA) is developed and used to find (weakly) Pareto optimal solutions to manufacturing and production problems that can be modelled as a symmetric multi-objective travelling salesman problem. Since there are a large number of solutions to these kinds of problems to reduce the computational effort and to provide more desirable and meaningful solutions to the decision maker this research focuses on using interactive input from the user to explore the most desirable parts of the efficient frontier instead of trying to reproduce the entire frontier. Here users define their preferences by selecting among five classes of objective functions and by specifying weighting coefficients bounds and optional upper bounds on indifference tradeoffs. This structure is married with the memetic algorithm - a random-key genetic algorithm hybridised by local search. The resulting methodology is an iterative process that continues until the decision maker is satisfied with the solution. The paper concludes with case studies utilising different scenarios to illustrate possible manufacturing and production related implementations of the methodology.
Citation - WoS: 8
Citation - Scopus: 11
An Improved Adaptive Subspace Tracking Algorithm Based on Approximated Power Iteration
(IEEE-INST Electrical Electronics Engineers Inc, 2018) Wu, Qiang; Zheng, Jian-Sheng; Dong, Zhicheng; Panayırcı, Erdal; Wu, Zhi-Qiang; Ren, Qingnuobu
A subspace tracking technique has drawn a lot of attentions due to its wide applications. The main objective of this approach is to estimate signal or noise subspace basis for the sample covariance matrix. In this paper we focus on providing a fast stable and adaptive subspace tracking algorithm that is implemented with low computational complexity. An alternative realization of the fast approximate power iteration (FAPI) method termed modified FAPI (MFAPI) is also presented. Rather than solving an inverse square root of a matrix employed in the FAPI the MFAPI applies the matrix product directly to ensure the orthonormality of the subspace basis matrix at each recursion. This approach yields a simpler derivation and is numerically stable while maintaining a similar computational complexity as compared with that of the FAPI. Furthermore we present a detailed mathematical proof of the numerical stability of our proposed algorithm. Computer simulation results indicate that the MFAPI outperforms many classical subspace tracking algorithms particularly at the transient-state step.
Citation - WoS: 12
Citation - Scopus: 14
Elastic Percolation of Swollen Polyacrylamide (paam)-Multiwall Carbon Nanotubes Composite
(Taylor & Francis Ltd, 2012) Evingür, Gülşen Akin; Pekcan, Önder
Polyacrylamide (PAAm)-multiwalled carbon nanotube (MWNT) composites were prepared via free radical cross-linking copolymerization with different amounts of MWNTs varying in the range between 0.1 and 50 wt%. The mechanical properties of swollen PAAm-MWNT composites were characterized by the tensile testing technique. A small content of embedded nanotubes dramatically changes the compressive elastic modulus of the composites. Compressive elastic modulus dramatically increases up to 1wt% MWNT on increasing nanotube content and then decreases presenting a critical MWNT value indicating that there is a sudden change in the material elasticity. The critical exponent y of elasticity below the critical MWNT content 1 wt% is found to be 0.58 which is consistent with the suggestions of percolation in the superelastic percolation network for PAAm-MWNT composite.
Citation - WoS: 11
Citation - Scopus: 15
Assessing and Selecting Sustainable Refrigerated Road Vehicles in Food Logistics Using a Novel Multi-Criteria Group Decision-Making Model
(Elsevier Science inc, 2024) Gorcun, Omer Faruk; Tirkolaee, Erfan Babaee; Kucukonder, Hande; Gargf, Chandra Prakash
In recent years, food loss and waste (FLW) have become an essential issue at the top of the international community's agenda. Since more people are afflicted by this problem every day, the global population would be forced into poverty and starvation without finding an immediate solution. Therefore, in order to decrease FLW, well-designed and sustainable food and cold supply chains (FCSCs) are needed. Additionally, refrigerated transportation systems can be crucial in developing sustainable supply chains. According to some empirical research, the technological capabilities of reefer vehicles or trailers differ significantly. Thus, selecting the reefer vehicle is a complex decision-making problem and selecting appropriate reefer vehicles may have a critical role in constructing successful supply chain systems and reducing food waste and loss. The current research proposes an efficient, robust and practical decision-making framework that can overcome uncertainties to tackle this decision-making problem. The managerial and strategic implications of the study also aid in decreasing FLW and restructuring FSC for industrial context and support to the UN's sustainable development goals (SDGs). Later, an exhaustive sensitivity analysis was conducted to examine the developed model's validity and application, confirming the model's robustness and dependability.
Citation - WoS: 3
Citation - Scopus: 3
Markdown Optimization in Apparel Retail Sector
(Springer international Publishing Ag, 2020) Yildiz, Sevde Ceren; Hekimoglu, Mustafa
Price discounts, known as markdowns, are important for fast fashion retailers to utilize inventory in a distribution channel using demand management. Estimating future demand for a given discount level requires the evaluation of historical sales data. In this evaluation recent observations might be more important than the older ones as majority of price discounts take place at the end of a selling season and that time period provides more accurate estimations. In this study, we consider a weighted least squares method for the parameter estimation of an empirical demand model used in a markdown optimization system. We suggest a heuristic procedure for the implementation of weighted least squares in a markdown optimization utilizing a generic weight function from the literature. We tested the suggested system using empirical data from a Turkish apparel retailer. Our results indicate that the weighted least squaresmethod is more proper than the ordinary least squares for the fast fashion sales data as it captures price sensitivity of demand at the end of a selling season more accurately.
Citation - Scopus: 1
Capacity Planning for Electricity Utility Call Centers: a Time Series Analysis Approach
(Institute of Electrical and Electronics Engineers Inc., 2024) Kavas, E.; Alsan, H.F.; Arsan, T.
Electric power systems are crucial for modern society, yet their reliability can be challenged by unforeseen disruptions, causing electricity supply disruptions. Call centers are essential for managing customer inquiries during such outages, acting as communication hubs for electricity utility companies. Effective capacity planning is vital for these call centers to maintain efficient operations and meet customer demands promptly. Proper workforce management ensures that enough skilled agents can handle calls effectively and maintain high service quality. Capacity planning begins with analyzing historical data to understand call volumes, patterns, and peak times. This data analysis identifies trends and factors influencing call patterns, enabling accurate forecasting of future demand and optimizing staffing levels. This paper provides a comprehensive overview of quantitative forecasting methods, focusing on Time Series Analysis applied to a dataset from a Turkish electric utility company that exhibits typical seasonal fluctuations. Specifically, the study examines the performance of AutoRegressive Integrated Moving Average and Seasonal AutoRegressive Integrated Moving Average models. Results indicate that both models perform well, with the Seasonal AutoRegressive Integrated Moving Average model demonstrating slightly superior performance compared to the AutoRegressive Integrated Moving Average model. This suggests that the Seasonal AutoRegressive Integrated Moving Average model may be more suitable for forecasting inbound calls at electricity utility call centers. This paper's detailed analysis and methodology offer valuable insights for optimizing operational efficiency, reducing costs, and enhancing customer satisfaction in dynamic and challenging operational scenarios. © 2024 IEEE.
Validation of Wind Turbine Model Software Simulation Using Real Time Windspeed Measurements
(Institute of Electrical and Electronics Engineers Inc., 2023) Polycarpou,A.; Shiacallis,S.; Christofides,N.; Papadakis,A.; Papadopoulos,T.; Ceylan,O.
Based on the achievements regarding the 2020 targets, the Renewable Energy Directive established a new, higher target for 2030, reflecting a significant increase of interest for renewable energy sources (RES). As a result, various new software simulation packages, featuring models of RES, have been developed and being used in academia as well as in industry for research, educational or training purposes. In this paper Wind turbine (WT) characteristics and wind speed data obtained from a commissioned wind farm in Cyprus are used to implement a simulation model in two different software programs featuring RES simulation capabilities. Power System Computer Aided Design (PSCAD) is used to investigate the electrical power output of a WT model, and KYAMOS software is used to investigate the modelling of the blades, the resulting primary torque and the resulting rotor rotational speed. The investigation result novelty is the establishment of the ability of the proposed, under development, software program to satisfy the three required characteristics. Therefore, Deviation from measured values of the turbine characteristics is observed for both programs, user interface and blade modelling, and the potential of integrating results of one software into the other is investigated. © 2023 IEEE.
Citation - WoS: 10
Citation - Scopus: 9
Viewpoint: Historic Urban Landscape Approach for Sustainable Urban Development
(Routledge Journals Taylor & Francis Ltd, 2018) Erkan Kösebay, Yonca
[Abstract Not Available]
Citation - Scopus: 8
Differences Across Generations and Stability of Values in the Turbulence of Social Change in Turkey
(Springer International Publishing, 2021) Sümer, N.; Mert, H.; Cemalcılar, Z.
This chapter explores culture specific dynamics of intergenerational value transmission and its potential effects on youth self-sufficiency in the Turkish context. Due to rapid socioeconomic changes and massive internal migration to urban areas in the last five decades, Turkey is experiencing a major transformation in the family structure, parenting values, and expectations from a young person. We propose that Kagitcibasi’s (2005) family model of “emotional interdependence” characterizing the dominant family system in Turkey as well as in the majority of the developing world provides a comprehensive framework for understanding how intergenerational differences in values would influence the motivation for economic self-sufficiency among youth. Our findings using semi-structured biographical interviews with 3 generations and 10 families from various cities suggest that wide social support system with strong family bonds and placing a high value on education are the common characteristics across generations and parenting styles. Findings suggest emotional interdependence found in families in Turkey allows a blend of authoritative, permissive and overprotective traits to varying degrees. Regardless of the dominant parental style, higher education and secure jobs are seen as a fundamental path to economic self-sufficiency especially during the economic hardship and social turmoil. Although older generations and families in rural regions focus more on traditional values, such as obedience and appropriate conduct or nurture (“terbiye” in Turkish), and traditional gender roles, younger generations and families in urban areas report higher gender equality and autonomy in a relational family context. Findings suggest that formal and informal education as well as training programs targeting unemployed youth should prioritize self-sufficiency and entrepreneurship and pay special attention to gender equality. Emotional interdependence of families in Turkey, with its strong emphasis on social support and investment in education, might be assistive in these efforts as well. © The Editor(s) (if applicable) and The Author(s) 2021.
Citation - WoS: 17
Citation - Scopus: 16
Hyperuricemia in hypothyroidism: Is it associated with post-insulin infusion glycemic response?
(Tohoku Univ Medical Press, 2003) Dariyerli, Nuran; Andican, Gülnur; Çatakoğlu, Alp Burak; Hatemi, Hüsrev; Burçak, Gülden
This experimental study was designed to examine whether hyperuricemia in hypothyroidism is associated with insulin resistance. For induction of hypothyroidism rabbits (n = 12) were administered methimazole orally (75 mg/100 g food) for 30 days. T-3 T-4 and TSH values measured in plasma prior to and at the end of the experimentation period revealed the establishment of hypothyroidism. In the euthyroid and hypothyroid states of rabbits crystalline porcine insulin was administered (0.1 unit/kg body weight) intraperitoneally and plasma glucose was measured at 0 15 30 45 and 60 minutes. Sum of post insulin infusion glucose values was considered to reflect insulin resistance. Creatinine clearance (GFR) and uric acid clearance (C-uA) were determined. Additionally triglycerides were measured in plasma and Mg2+ both in erythrocytes and in plasma. Due to hypothyroidism: i) The glycemic response to insulin was not altered. ii) GFR and C-uA were both decreased but C-uA/GFR unchanged. iii) Triglycerides in plasma decreased. iv) Mg2+ concentration increased in plasma whereas decreased in erythrocytes. Several associations were observed between the variables on correlation analysis. On the basis of our data it could be suggested that insulin resistance does not exist in hypothyroidism. Hyperuricemia observed in hypothyroidism should be considered to be secondary to decreased renal excretion but not as an indicator of insulin resistance. (C) 2003 Tohoku University Medical Press.
Citation - WoS: 5
Citation - Scopus: 6
Effect of Lcst on the Swelling of Paam-Nipa Copolymers: a Fluorescence Study
(Springer, 2012) Evingür, Gülşen Akin; Pekcan, Önder
Temperature sensitive copolymers were prepared by free radical crosslinking copolymerization in aqueous solution with different molar percentage of N-isopropylacrylamide (NIPA) and acrylamide (AAm) monomers. NN'-methylenebis (acrylamide) (BIS) and ammonium persulfate (APS) were used as a crosslinker and an initiator respectively. The steady-state fluorescence (SSF) technique was used to determine the low critical phase transition temperature (LCST) for PAAm-NIPA copolymers. Swelling experiments were performed in water at various temperatures by real time monitoring of pyranine (Py) fluorescence intensity I which decreased as swelling proceeded. The Stern-Volmer equation is modified for low quenching efficiencies to interpret the behavior of pyranine intensity during the swelling of PAAm-NIPA copolymers. The Li-Tanaka equation was used to determine the swelling time constants tau (1) and the cooperative diffusion coefficients D (0) from fluorescence intensity weight and volume variations of the copolymers at various temperatures. It was observed that tau (1) first increased up to LCST and then decreased
Isolated Left Ventricular Noncompaction: Magnetic Resonance Imaging Findings
(2005) Kantarci, M.; Duran, C.; Sildiroğlu, O.; Ulusoy, L.; Mutlu, H.; Karaman, B.
[No abstract available]
Citation - Scopus: 1
Multi-Agent Model of Electricity Networks - a Perspective on Distribution Network Charges
(Institute of Electrical and Electronics Engineers Inc., 2019) Pisica, Ioana; Ceylan, Oğuzhan
In the UK, DNOs are regulated by Ofgem to use two common distribution use of system charging methodologies: Common Distribution Charging Methodology and Extra-High Voltage Distribution Charging Methodology. To account for the changing landscape of the energy sector, Ofgem has recently published a consultation paper on changes to DUoS charging structure. This paper looks into the implications of distribution network charging in consumer-level adoption of low carbon technologies and vice-versa, using an agent-based model approach.
Citation - WoS: 4
Citation - Scopus: 7
Atomic Force Microscopy and Spectroscopy Studies of Annealed Ce/Ti Mixed Oxide Thin Films Prepared by Sol-Gel Process
(Elsevier Science Bv, 2006) Ghodsi, Farhad E.; Tepehan, Fatma Zehra; Tepehan, Galip Gültekin
Mixed Ce/Ti/Zr oxide thin films with a molar ratio of 0.5:0.25:0.25 were prepared using the sol-gel process and deposited on glass substrates by the dip coating technique. The effect of heat treatment temperature on surface morphology of the films was examined by atomic force microscopy AFM. The optical transmittance and reflectance of the films were measured over the spectral range from 350 to 1000 nm. The refractive index and extinction coefficient and thickness of the films were determined as a function of the heat treatment temperature. The refractive index increased from 1.51 to 2.02 at lambda = 600 nm and the extinction coefficient values increased from 0.006 to 0.094 while the thickness of the films decreased from 81 nm to 45 nm when annealing temperature increased from 100 degrees C to 500 degrees C. The results show that the optical properties and surface morphology of the mixed Cc/Ti/Zr oxide thin films were affected by annealing temperature. (c) 2006 Elsevier B.V. All rights reserved.
Citation - WoS: 2
Citation - Scopus: 5
Performance of Space-Time Coded Systems With Transmit Antenna Selection
(IEEE, 2007) Güçlüoğlu, Tansal; Duman, Tolga M.
We deal with transmit antenna selection for space-time coded (STC) systems over multiple input multiple output (MIMO) channels. Using pairwise error probability analysis and simulation results we show that transmit antenna selection based on received power levels does not reduce the achievable diversity order for full rank STCs. Initially we prove the results for Rayleigh flat fading channels and then we state our expectations for the case of frequency selective (FS) fading. In addition to the study of full rank codes we also consider rank deficient space-time codes and determine achievable diversity orders with transmit antenna selection.
New Generation Android Operating System-Basedmobile Application: Rss/News Reader
(Springer Verlag, 2015) Arsan, Taner; Erşahin, Mehmet Arif; Alp, Ebru
RSS (Rich Site Summary)/News Reader is a web-based Android OS application developed by using PhoneGap framework. HTML5 CSS and JavaScript are basically used for implementation instead of native Android programming language. This application has a production process like a web application because it is actually a fully working web program which is wrapped by PhoneGap framework. This means the application could be used on almost every mobile platform with making some basic arrangements.RSS/News Reader mobile application takes advantage of both flexibility of web design and built-in features of the device it is installed. This combination provides a complete mobile application which eliminates the need to use different native languages with its hybrid form. This hybrid structure makes mobile programming faster and easier to implement.In this new generation operating system-based mobile application a combination of PhoneGap framework HTML5 CSS3 JavaScript jQuery Mobile Python and Django is used for implementation. © Springer International Publishing Switzerland 2015.
Citation - WoS: 27
Citation - Scopus: 32
A Fuzzy-Based Method for Objects Selection in Blockchain-Enabled Edge-Iot Platforms Using a Hybrid Multi-Criteria Decision-Making Model
(Mdpi, 2022) Gardas, Bhaskar B.; Heidari, Arash; Navimipour, Nima Jafari; Unal, Mehmet
The broad availability of connected and intelligent devices has increased the demand for Internet of Things (IoT) applications that require more intense data storage and processing. However, cloud-based IoT systems are typically located far from end-users and face several issues, including high cloud server load, slow response times, and a lack of global mobility. Some of these flaws can be addressed with edge computing. In addition, node selection helps avoid common difficulties related to IoT, including network lifespan, allocation of resources, and trust in the acquired data by selecting the correct nodes at a suitable period. On the other hand, the IoT's interconnection of edge and blockchain technologies gives a fresh perspective on access control framework design. This article provides a novel node selection approach for blockchain-enabled edge IoT that provides a quick and dependable node selection. Moreover, fuzzy logic to approximation logic was used to manage numerical and linguistic data simultaneously. In addition, the Technique for Order of Preference by Similarity to Ideal Solution (TOPSIS), a powerful tool for examining Multi-Criteria Decision-Making (MCDM) problems, is used. The suggested fuzzy-based technique employs three input criteria to select the correct IoT node for a given mission in IoT-edge situations. The outcomes of the experiments indicate that the proposed framework enhances the parameters under consideration.

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