74 research outputs found
Fuzzy rule-based demand forecasting for dynamic pricing
No full textEkinci, Yeliz (Dogus Author) -- Conference full title: 10th International FLINS Conference, Istanbul, Turkey, 26-29 August 2012In this study, the pricing problem of a transportation service provider company is considered. Our goal is to find optimal prices by using probabilistic dynamic programming. A fuzzy rule-based expert system is used to identify the demand levels under different price levels and other characteristics of the journey. The results obtained by optimal price policies show that the revenue levels and the capacity utilization increase by applying dynamic pricing policy instead of fixed pricing. Thus, the diversification of price policies under different conditions is advantageous for the company.Belgian Nuclear Research Centre (SCK-CEN), Ghent Universit
A DEA and goal programming approach to demand assignment problem
No full textYeliz, Ekinci (Dogus Author)Assignment problem has always been a popular problem for production and operations research. Many methods and heuristics have been developed for these kinds of problems. This research deals with the problem of an automotive company’s driver belt assembly supply from its by-industry suppliers. First, the suppliers are evaluated by data envelopment analysis (DEA), which is a mathematical modelling approach finding the relative efficiencies of the decision-making units (DMUs). Later on, the suppliers that are found inefficient are eliminated and only the efficient suppliers are included for the assignment problem. Preemptive goal programming (PGP) is applied for the assignment of demand in order to satisfy the goals and the demand of the company by taking into account the priorities given by the company
An analysis of gifted and non-gifted fifth graders' strategic flexibility1
Get PDFFlexibility constitutes a crucial element of creativity, and there exists a significant correlation between mathematical problem-solving abilities and creativity. Moreover, non-routine problems necessitate students to employ critical thinking, creativity, and various problem-solving techniques. Hence, the objective of this holistic multiple case study is to examine the problem solving success and strategic flexibility of both gifted and non-gifted fifth graders in non-routine problem solving, as well as exploring the relationship between these factors. To achieve this aim, a total of eight non-routine problems were presented to 40 fifth graders, with 20 being gifted and 20 non-gifted students. The students' written solutions were collected, followed by individual interviews. Subsequently, the solutions were evaluated in terms of success and strategic flexibility. The results indicated that gifted students demonstrated more frequent use of indicators compared to their non-gifted counterparts. Additionally, a trend towards clustering in the medium category for gifted students and the weak category for non-gifted students was observed. Both groups included a limited number of students with high levels of flexibility. Notably, a significant relationship between flexibility and success scores was only evident among non-gifted students. Disparities in flexibility and success between gifted and non-gifted students were apparent. The implications of these findings for mathematics education were discussed, alongside recommendations for future research
The application of UHF passive RFID technology for the effectiveness of retail/consumer goods supply chain management
No full textEkinci, Yeliz (Dogus Author) -- Conference full title: 1st annual RFID Eurasia 2007 Conference: September 5-6, 2007, Istanbul, Turkey.In this research, the application of radio frequency identification (RFID) technology, which is the technology used for tracking objects using radio waves with the help of a reader, an antenna and a chip, is investigated on the retail/consumer goods supply chain. Consumer goods probably take the biggest pie by quantity among the goods produced in the world, therefore the supply chain of this industry has to be robust. Tracking this large amount of products is a critical subject all over the world, in this study ultra-high frequency (UHF) passive RFIDs, which operate without battery and a very small-sized antenna and which are advantageous for their size and cost, are particularly examined for global supply chain of retail/consumer goods. The benefits of the technology are summarized and a work flow is also represented for the supply chain operations among manufacturers, distribution centers and retailers applying RFID, barcode and GPS technologies together
Dynamic Rolling Horizon Control Approach for a University Campus
No full textOnen, Ahmet/0000-0001-7086-5112; Yoldas, Yeliz/0000-0002-9821-9339;An energy management system based on the rolling horizon control approach has been proposed for the grid-connected dynamic and stochastic microgrid of a university campus in Malta. The aims of the study are to minimize the fuel cost of the diesel generator, minimize the cost of power transfer between the main grid and the micro grid, and minimize the cost of deterioration of the battery to be able to provide optimum economic operation. Since uncertainty in renewable energy sources and load is inevitable, rolling horizon control in the stochastic framework is used to manage uncertainties in the energy management system problem. Both the deterministic and stochastic processes were studied to approve the effectiveness of the algorithm. Also, the results are compared with the Myopic and Mixed Integer Linear Programming algorithms. The results show that the life span of the battery and the associated economic savings are correlated with the SOC values. (c) 2021 The Author(s). Published by Elsevier Ltd
Landscape-Based Fire Resilience: Identifying Interaction Between Landscape Dynamics and Fire Regimes in the Mediterranean Region
No full textWildfires are widely viewed as key evolving inputs of Mediterranean ecosystem. But anthropogenic climate changes and other socioecological recessions have transformed normal wildfire into megafire. The paradigm shift is needed since the suppression capacity has been increasingly overcome from the fire department. This research is aiming to integrate diverse landscape dynamics and fire regimes, to interpret the interactions between them and identify a series of heterogeneous fire typologies in the Mediterranean region in order to support the application of landscape-based approaches. By classifying the land system dynamics into meteorologic, physiographic, biological and anthropogenic indicators (in relation with wildfire ignition and propagation), geographic information system based approaches and statistic analysis are applied to create diagnostic mappings. The results establish 10 types of landscape-based fire typologies which can be used as the decision support tool to prioritize risk mechanism and then lead to mitigate wildfire risk by changing contextual territorial elements in landscape system in order to create an integral long time territorial design.Green Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work publicUrban Data ScienceUrban Desig
Problems and Factors Affecting the Sexual Lives of Patients with Multiple Sclerosis Living in Turkey
No full textSexual dysfunction is frequently reported by patients with Multiple Sclerosis (MS), and this topic is receiving more attention in Turkey with many recent studies having been conducted. A descriptive study was conducted to determine the sexual problems and factors affecting the sexual lives of patients with MS living in Turkey. A demographic questionnaire and the evaluation form of sexual satisfaction were completed 59 study participants. The patients' symptom severity evaluated with the MS-Related Symptom Scale (MS-RS) and sexual problems evaluated with Multiple Sclerosis Intimacy and Sexuality Questionnaire-19 (MSISQ-19). Data has been collected from a face-to-face interview performed by a neurology unit nurse. Results indicated that 27.1% of the participating MS patients had sexual problems, and the difference of patients' sexual satisfaction scores was statistically significant both before and after onset of disease. It was also determined that the relation between MS-RS and MSISQ-19 was significant in a positive way. The total MSISQ-19 score was higher and the difference was significant for participants who were married, who had insufficient income, who engaged in exercise, who had tense relationships with their spouse, who thought that sexual fulfillment is important and that the medicines had changed their sexual life, and who spoke with their spouse about sexual problems. Many factors are involved in the development of sexual difficulties in MS patients. The study determined that as the symptom intensity of MS patients increases, sexual problems also increase. Also this study have shown that after the onset of MS sexual satisfaction decreases. For these reasons, it has been suggested that MS patients and their spouses should be given information about symptom control, and the nurses should offer counsel to the spouses concerning this important topic. Furthermore, patients also need to know the side effects of the medicines they must take, suitable exercises and social activities should be planned, at-home care should be arranged for patients who need it, and free care should also be arranged for those who cannot afford it otherwise
BRIDGE ESTIMATOR AS AN ALTERNATIVE TO DICKEY-PANTULA UNIT ROOT TEST
No full text10th International Days of Statistics and Economics -- SEP 08-10, 2016 -- Prague, CZECH REPUBLICWOS: 000389515100052Economic series may have unit roots. There are different methods to test unit roots in the literature. Recent studies show the advantages of using Bridge estimator for choosing the lag length of unit root tests and computing test statistics. This method penalizes the parameters of the model with a positive shrinkage parameter. For a suitable choice of the shrinkage parameter, the limiting distributions of the Bridge estimator can have positive probability mass at 0 when the true value of the parameter is zero for stationary series. Therefore, the Bridge estimator provides a method that can be used for the model selection and estimation simultaneously. It is known in the literature that Bridge estimator does the model selection while simultaneously distinguishing between stationary and unit root models for series with a unit root as well. In this study, we propose Bridge estimator to determine the integration order of series with more than one unit root. In order to do this, we apply the Bridge estimator to Dickey-Pantula model. We evaluate the size and power of the Bridge estimator with a simulation study and compare our proposed estimator with the existent Dickey-Pantula test.Univ Econ, Dept Stat & Probabil, Univ Econ, Dept Microecon, Tech Univ Kosice, Fac Econ, Ton Duc Thang UnivCukurova University Research FundCukurova University [SDK-2016-5277, IIBF2012BAP4]This research is supported by Cukurova University Research Fund (SDK-2016-5277)
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