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Open Access
Doppelgänger in Orhan Pamuk’s The Black Book
(Ahmet Yesevi Üniversitesi, 01.01.2011) Çancı Çalışaneller, Saniye; Undergraduate English Program; ÇALIŞANELLER, Saniye Çancı
This article examines Orhan Pamuk’s The Black Book in connection with the doppelgänger motif in literature. In The Black Book, Galip’s wife Rüya and his cousin Jelal disappear all of a sudden, and the novel narrates Galip’s search for them who remain invisible throughout the novel. There is a conflict between the characters Galip and Jelal, and this article claims that although the two characters are depicted in the novel as Galip and Jelal, Jelal turns out to be the second self or author self of Galip. Thus, the doppelgänger motif will also be associated with authorship.
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Detecting credit card fraud by modified Fisher discriminant analysis
(Elsevier, 01.04.2015) Mahmoudi, Nader; Duman, Ekrem; Industrial Engineering; DUMAN, Ekrem; Mahmoudi, Nader
In parallel to the increase in the number of credit card transactions, the financial losses due to fraud have also increased. Thus, the popularity of credit card fraud detection has been increased both for academicians and banks. Many supervised learning methods were introduced in credit card fraud literature some of which bears quite complex algorithms. As compared to complex algorithms which somehow over-fit the dataset they are built on, one can expect simpler algorithms may show a more robust performance on a range of datasets. Although, linear discriminant functions are less complex classifiers and can work on high-dimensional problems like credit card fraud detection, they did not receive considerable attention so far. This study investigates a linear discriminant, called Fisher Discriminant Function for the first time in credit card fraud detection problem. On the other hand, in this and some other domains, cost of false negatives is very higher than false positives and is different for each transaction. Thus, it is necessary to develop classification methods which are biased toward the most important instances. To cope for this, a Modified Fisher Discriminant Function is proposed in this study which makes the traditional function more sensitive to the important instances. This way, the profit that can be obtained from a fraud/legitimate classifier is maximized. Experimental results confirm that Modified Fisher Discriminant could eventuate more profit.
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Unmanned aerial vehicle relay networks
(Help Cookies Privacy Statement Accessibility Modern Slavery Act Statement Legal notices The Institution of Engineering and Technology, 202) Adam, Evşen Yanmaz; Electrical & Electronics Engineering; Davoli, L.; Ferrari, G.; ADAM, Evşen Yanmaz
N/A
Open Access
Ambulance location for maximum survival
(Wiley, 2008-02) Erkut, Erhan; Ingolfsson, A.; Erdoğan, G.; Business Administration; ERKUT, Erhan
This article proposes new location models for emergency medical service stations. The models are generated by incorporating a survival function into existing covering models. A survival function is a monotonically decreasing function of the response time of an emergency medical service (EMS) vehicle to a patient that returns the probability of survival for the patient. The survival function allows for the calculation of tangible outcome measures—the expected number of survivors in case of cardiac arrests. The survival-maximizing location models are better suited for EMS location than the covering models which do not adequately differentiate between consequences of different response times. We demonstrate empirically the superiority of the survival-maximizing models using data from the Edmonton EMS system.
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Assessment of patient classification in appointment system design
(Production and Operations Management Society, 2008-05) Çayırlı, Tuğba; Veral, E.; Rosen, H.; Business Administration; ÇAYIRLI, Tuğba
This paper investigates two approaches to patient classification: using patient classification only for sequencing patient appointments at the time of booking and using patient classification for both sequencing and appointment interval adjustment. In the latter approach, appointment intervals are adjusted to match the consultation time characteristics of different patient classes. Our simulation results indicate that new appointment systems that utilize interval adjustment for patient class are successful in improving doctors' idle time, doctors' overtime and patients' waiting times without any trade-offs. Best performing appointment systems are identified for different clinic environments characterized characterized by walk-ins, no-shows, the percentage of new patients, and the ratio of the mean consultation time of new patients to the mean consultation time of return patients. As a result, practical guidelines are developed for managers who are responsible for designing appointment systems.
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Energetic reasoning revisited: application to parallel machine scheduling
(Springer Science+Business Media, 2008-08) Hidri, L.; Gharbi, A.; Haouari, Mohamed; Industrial Engineering; HAOUARI, Mohamed
We consider the problem of minimizing makespan on identical parallel machines subject to release dates and delivery times. We present several new feasibility tests and adjustment techniques that consistently improve theclassical energetic reasoning approach. Computational results carried out on a set of hard instances provide strong evidence that the performance of a state-of-the-art exact branch-and-bound algorithm is substantially improved through embedding the proposed enhanced energetic reasoning.
Open Access
Optimal ambulance location with random delays and travel times
(Springer Science+Business Media, 2008-09) Ingolfsson, A.; Budge, S.; Erkut, Erhan; Business Administration; ERKUT, Erhan
We describe an ambulance location optimization model that minimizes the number of ambulances needed tonprovide a specified service level. The model measures service level as the fraction of calls reached within a given time standard and considers response time to be composed of a random delay (prior to travel to the scene) plus a random travel time. In addition to modeling the uncertainty in the delay and in the travel time, we incorporate uncertainty in the ambulance availability in determining the response time. Models that do not account for the uncertainty in all three of these components may overestimate the possible service level for a given number of ambulances and underestimate the number of ambulances needed to provide a specified service level. By explicitly modeling the randomness in the ambulance availability and in the delays and the travel times, we arrive at a more realistic ambulance location model. Our model is tractable enough to be solved with general-purpose optimization solvers for cities with populations around one Million. We illustrate the use of the model using actual data from Edmonton.
Open Access
Winners and losers in a major price war
(American Marketing Association, 2008-10) Heerde, H. J. van; Gijsbrechts, E.; Pauwels, Koen Hendrik; Business Administration; PAUWELS, Koen Hendrik
Although retail price wars have received much business press and some research attention, it is unclear how they affect consumer purchase behavior. This article studies an unprecedented price war in Dutch grocery retailing that started in fall 2003, initiated by the market leader to halt its sliding market share. The authors investigate the short- and longterm effects of the price war on store visits, on spending, and on the sensitivity of these decisions to weekly prices and price image. They use a unique data set with consumer hand-scan and perceptual data for a national panel of 1821 households, covering two years before and two years after the price war started. Although the price war initially entailed more shopping around and increased spending, spending per visit ultimately dropped because consumers redistributed their purchases across stores. The price war made consumers more sensitive to weekly prices and price image, which helped both the chain that showed an improvement in price image (the price war initiator) and the chains that already had a favorable price image (hard discounters). The price war initiator managed to halt the slide in its market share, and its stock price improved. The losers were the rival mid-level and high-end chains. Unlike the initiator, their price image did not improve, and they suffered from increased price image sensitivity. The authors provide managerial implications for firms that are (or about to be) involved in a price war.
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Optimal solution of the discrete cost multicommodity network design problem
(Elsevier, 2008-10-15) Mrad, M.; Haouari, Mohamed; Industrial Engineering; HAOUARI, Mohamed
We investigate a multicommodity network design problem where a discrete set of Technologies with step-increasing cost and capacity functions should be installed on the edges. This problem is a fundamental network design problem having many important applications in contemporary telecommunication networks. We describe an exact constraint generation approach and we show that the conjunctive use of valid inequalities, bipartition inequalities that are generated using max-flow computations, as well as an exact separation algorithm of metric inequalities makes it feasible to solve to optimality instances with up to 50 nodes and 100 edges.
Open Access
Private-label use and store loyalty
(American Marketing Association, 2008-11) Ailawadi, K. L.; Pauwels, Koen Hendrik; Steenkamp, J.-B. E. M.; Business Administration; PAUWELS, Koen Hendrik
The authors develop an econometric model of the relationship between a household’s private-label (PL) share and its behavioral store loyalty. The model includes major drivers of these two behaviors and controls for simultaneity and nonlinearity in the relationship between them. The model is estimated with a unique data set that combinescomplete purchase records of a panel of Dutch households with demographic and psychographic data. The authorsestimate the model for two retail chains in the Netherlands the leading service chain with a well-differentiatedhigh-share PL and the leading value chain with a lower-share PL. They find that PL share significantly affects all three measures of behavioral loyalty in the study: share of wallet, share of items purchased, andshare of shopping trips. In addition, behavioral loyalty has a significant effect on PL share. For the service chain, the authors find that both effects are in the form of an inverted U. For the value chain, the effects are positive and nonlinear, but they do not exhibit nonmonotonicity, because PL share has not yet reached high enough levels. The managerial implications of this research are important. Retailers can reap the benefits of a virtuous cycle; greater PL share increases share of wallet, and greater share of wallet increases PL share. However, this virtuous cycle operates only to a point because heavy PL buyers tend to be loyal to price savings and PLs in general, not to the PL of any particular chain.
Open Access
A review of timetabling and resource allocation models for light-rail transportation systems
(2009) Öncül, S. D.; Aykaç, Didem Selcen Öztürkcan; Bayraktar, D.; Çelebi, D.; Business Administration; ÖZTÜRKCAN AYKAÇ, Didem Selcen
This paper surveys the relevant operations research literature on timetabling and resource allocationproblems with a special attention paid to the transportation systems. The purpose of this review is to define the critical objectives, determine the key components and identify the key issues for developing a comprehensive mathematical model for timetabling of light rail transit vehicles in sequence with the assignment of drivers as an available resource. In doing so, the implications of the emerging timetabling research is discussed, components of the mathematical models proposed are reviewed, and the extend they reflect real business practices are analyzed. Finally, fundamental issues and primary elements of a simple model in association with general timetabling and resource allocation problems are presented.
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An actor-network theory (ANT) approach: analysis of Turkish e-government gateway initiative
(2009) Aykaç, Didem Selcen Öztürkcan; Kervenoael, R. de; Kasap, N.; Eryarsoy, E.; Business Administration; ÖZTÜRKCAN AYKAÇ, Didem Selcen
There are various models proposed in the literature to analyze trajectories of e-Government projects in terms of success and failure. Yet, only the Actor-Network Theory (ANT) perspective (Heeks and Stanforth, 2007) considers the interaction factors among network actors and actants. This paper proposes the ANT for approaching to the Turkish e-Government Gateway initiative as a case study. In doing so, it provides valuable insight in terms of both local and global actornetworks which surround the initiative.
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Capacity of wireless ad-hoc broadcast networks under realistic channel models
(IEEE, 2009) Atıcı, Çağdaş; Sunay, Mehmet Oğuz; Computer Science; SUNAY, Mehmet Oğuz; Atıcı, Çağdaş
In a wireless broadcasting scenario, some of the nodes can help the source node by forwarding the received information. Due to the interference from multiple transmissions, selection of these nodes directly affects the performance of the system under a given total power and hop constraint. In this paper, we first analytically find the number and the positions of the rebroadcasting nodes that achieve the optimal broadcast capacity under the continuum model. Following the results of this part, we propose two heuristics, one centralized and another distributed, for relay selection in practical scenarios. Then, we discuss the broadcast capacity performances of these algorithms under different system settings. The results illustrate that using a distributed relay selection method brings significant gains to the broadcast capacity under a realistic system model.
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Metal CMP optimization based on chemically formed thin film analysis
(The Electrochemical Society, 2009) Başım, Gül Bahar; Mechanical Engineering; BAŞIM DOĞAN, Gül Bahar
The conventional demands for development in semiconductor industry are changing as the Moore's Law is approaching to its limits. This paper demonstrates a theoretical optimization approach for the planarization of metal films by Chemical Mechanical Polishing (CMP) process. Optimal removal rate and a smooth surface finish post CMP can be achieved by the combined effect of the chemical and mechanical components of the process. Metal CMP necessitates a protective oxide film formation in the presence of surface active agents, corrosives, pH regulators etc' to achieve global planarization. Formation and mechanical properties of the chemically modified films determine the stresses develop in the film structure delineating the stability of the chemically altered films on the surface of the metal wafer. The balance between the stresses built in the film structure versus the mechanical actions provided during the process can be used to optimize the process variables and furthermore help define new planarization techniques for the next generation microelectronic device manufacturing which is expected to deal with atomic level structures.
Open Access
MathOptimizer: a nonlinear optimization package for mathematica users
(2009) Kampas, F. J.; Pinter, Janos D.; Industrial Engineering; PINTER, Janos
Mathematica is an advanced software system that enables symbolic computing, numerics, program code development, model visualization and professional documentation in a unified framework. Our MathOptimizer software package serves to solve global and local optimization models developed using Mathematica. We introduce MathOptimizer’s key features and discuss its usage options that support a range of operational modes. The numerical capabilities of the package are illustrated by simple and more advanced examples, pointing towards a broad range of potential applications.
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Pricing of national brands versus store brands: market power components, findings and research opportunities
(Edward Elgar Publishing, 2009) Pauwels, Koen Hendrik; Srinivasan, S.; Business Administration; Rao, V. R.; PAUWELS, Koen Hendrik
Among the most important activities for supermarket retailers is the creation and marketing of store brands, also known as private label brands. Given the increasing quality-equivalence between national brands and store brands, they have become direct competitors, and pricing decisions should take this into account. In most cases, national brands still possess some degree of pricing and market power over store brands. In this chapter, we define three components of market power for national brands versus store brands: (1) price premium; (2) volume premium; and (3) margin premium. Our chapter proceeds along the following lines. First, we delineate the factors that are the most important drivers of the three components of premium. Second, we discuss managerial implications about key success factors in the pricing of national brands and store brands. A key contribution of this chapter is that we incorporate emerging insights from the marketing literature on the pricing and market power of national brands versus store brands. Finally, we conclude by offering important future research directions.
Open Access
Social e-atmospherics in practice (or not): a French and Turkish web designers’ perspectives
(2009) Bisson, C.; Kervenoael, R. de; Aykaç, Didem Selcen Öztürkcan; Business Administration; ÖZTÜRKCAN AYKAÇ, Didem Selcen
Little is known about the development of social e- atmospherics. And yet, e-atmospherics havemotivated an emerging body of research which reports that both better layouts and‘recognized’ atmospherics encourage consumers to modify their shopping habits. While the literature has analyzed mainly the functional (design) aspect of e-atmospherics, little has been done in terms of linking its characteristics’ to social (co-) creation. This paper attempts to redress the imbalance by exploring the anatomy from a website designer perspective of the social dimension of design in relation to e-atmospherics, which includes factors such as the aesthetic design of space and the influence of visual cues as a socially constructed meaning. We identify the challenges that web designers as social agents, who interact within intangible social reference sets, restricted by social standards, value, beliefs, status and duties, face daily within their work. We aim to review the current understanding of the importance and voluntary integration of social cues displayed by web designers from a mature market and an emerging market, and provides an analysis based recommendation towards the development of an integrated e-social atmospheric framework. Results report exploratory findings from questionnaires with 10 French and 16 Turkish web designers. These allow us to re-interpret the web designers’ reality regarding social e-atmospherics. We contend that by comprehending (before any consumer/client input) social capital, daily micro practices, habits and routine of designers, a deeper understanding of social e-atmospherics possible functions in the future will be unpacked.
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On the broadcast capacity of wireless multihop interference networks
(IEEE, 2009) Atıcı, Çağdaş; Sunay, Mehmet Oğuz; Computer Science; SUNAY, Mehmet Oğuz; Atıcı, Çağdaş
This paper is concerned with wireless broadcasting in multihop networks where a selected number of relay nodes may aid the source node in the broadcast under a given total energy and hop constraint. We study an ad-hoc network with infinitely many nodes and analytically find the number and positions of rebroadcasting relay nodes to achieve the optimal broadcast capacity. The interference due to multiple transmissions in the geographical area is taken into account. Based on the theoretical findings, we then propose one distributed and one centralized heuristic for relay selection in wireless broadcasting. We discuss the broadcast capacity performances and CSI (channel state information) requirements of these algorithms. The results illustrate that the benefits of peer-assisted broadcasting are more pronounced in the centralized relay selection algorithm when compared to the fully randomized and distributed selection under a realistic system model.
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Sleepwalking in İstanbul: a man in anguish in A. H. Tanpinar's A Mind at Peace
(Taylor & Francis, 2009) Günay-Erkol, Çimen; Humanities and Social Sciences; ERKOL, Çimen Günay
Ahmet Hamdi Tanpınar's (1901-62) novels reflect the dichotomy within early twentieth-century Turkey: a nation maintaining past tradition yet concurrently embracing modernity. Tanpınar explores the Ottoman legacy of Turkish modernity and questions acute social and cultural change. Scholarly interest in this aspect of Tanpınar's novels has greatly eclipsed all other aspects, as most critics analyze Tanpınar's intentions primarily in light of his political ideologies or philosophical attachments. This article challenges Tanpınar's readers to consider him in a new light through an analysis of A Mind at Peace (2008), a multidimensional narrative that addresses an orphan boy's rites of passage, which lead to manhood, within a broad and perplexing story of continuity and change in Turkey. To understand the novel as a whole, this article asserts, one must first comprehend the protagonist's precarious masculinity and his gender anxieties.
Open Access
Optimizing offer sets based on user profiles
(Social Science Research Network, 2009) Atahan, Pelin; Johar, M.; Sarkar, S.; Sectoral Education and Professional Development; DEMİRCİLER, Pelin Atahan
Personalization and recommendation systems are being increasingly utilized by ecommerce firms to provide personalized product offerings to visitors at the firms’ web sites. These systems often recommend, at each interaction, multiple items (referred to as an offer set) that might be of interest to a visitor. When making recommendations firms typically attempt to maximize their expected payoffs from the offer set. This paper examines how a firm can maximize its expected payoffs by leverag ing th e kn owledge of the profiles of visitors to their site. We provide a methodology that accounts for the interactions among items in an offer set in order to determine the expected payoff. Identifying the optimal offer set is a difficult problem when the number of candidate items to rec ommend is large. We develop an efficient heuristic for this problem, and show that it performs well for both small and large problem instances.

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