Showing papers by "Yaşar University published in 2012"

Optimal unit-load warehouse designs for single-command operations

Abstract: We present a continuous space model for travel in a unit-load warehouse that allows cross-aisles and picking aisles to take on any angle. The model produces optimal designs for one, two, and three-cross-aisle warehouses, which are called chevron, leaf, and butterfly designs. We then use a more accurate discrete model to show which designs are best for a wide range of warehouse sizes. We show that the chevron design, which is new to theory and to practice, is the best design for many industrial applications.

Construction of the Turkish National Corpus (TNC)

Abstract: This paper addresses theoretical and practical issues experienced in the construction of Turkish National Corpus (TNC). TNC is designed to be a balanced, large scale (50 million words) and general-purpose corpus for contemporary Turkish. It has benefited from previous practices and efforts for the construction of corpora. In this sense, TNC generally follows the framework of British National Corpus, yet necessary adjustments in corpus design of TNC are made whenever needed. All throughout the process, different types of open-source software are used for specific tasks, and the resulting corpus is a free resource for non-commercial use. This paper presents TNC's design features, web-based corpus management system, carefully planned workflow and its web-based user-friendly search interface.

Young people's topography of musical functions: Personal, social and cultural experiences with music across genders and six societies

Abstract: How can we understand the uses of music in daily life? Music is a universal phenomenon but with significant interindividual and cultural variability. Listeners' gender and cultural background may influence how and why music is used in daily life. This paper reports the first investigation of a holistic framework and a new measure of music functions (RESPECT-music) across genders and six diverse cultural samples (students from Germany, Kenya, Mexico, New Zealand, Philippines, and Turkey). Two dimensions underlie the mental representation of music functions. First, music can be used for contemplation or affective functions. Second, music can serve intrapersonal, social, and sociocultural functions. Results reveal that gender differences occur for affective functions, indicating that female listeners use music more for affective functions, i.e., emotional expression, dancing, and cultural identity. Country differences are moderate for social functions (values, social bonding, dancing) and strongest for sociocultural function (cultural identity, family bonding, political attitudes). Cultural values, such as individualism-collectivism and secularism-traditionalism, can help explain cross-cultural differences in the uses of music. Listeners from more collectivistic cultures use music more frequently for expressing values and cultural identity. Listeners from more secular and individualistic cultures like to dance more. Listeners from more traditional cultures use music more for expressing values and cultural identity, and they bond more frequently with their families over music. The two dimensions of musical functions seem systematically underpinned by listeners' gender and cultural background. We discuss the uses of music as behavioral expressions of affective and contemplative as well as personal, social, and sociocultural aspects in terms of affect proneness and cultural values.

Theoretical and Empirical Review of Asset Pricing Models: A Structural Synthesis

Abstract: The purpose of this paper is to give a comprehensive theoretical review devoted to asset pricing models by emphasizing static and dynamic versions in the line with their empirical investigations. A considerable amount of financial economics literature devoted to the concept of asset pricing and their implications. The main task of asset pricing model can be seen as the way to evaluate the present value of the pay offs or cash flows discounted for risk and time lags. The difficulty coming from discounting process is that the relevant factors that affect the pay offs vary through the time whereas the theoretical framework is still useful to incorporate the changing factors into an asset pricing models. This paper fills the gap in literature by giving a comprehensive review of the models and evaluating the historical stream of empirical investigations in the form of structural empirical review.

Ministers’ statements: a policy implementation instrument for sustainable tourism?

Abstract: Consistent communication of tourism policies by tourism ministers might raise public and industry awareness and promote support for sustainable tourism. The statements made by ministers contain messages that can inform the public and industry stakeholders, and potentially, these statements can draw attention to sensitive issues and bring about changes in practices that encourage sustainability in the tourism industry. Analyzing the statements of the five most recent tourism ministers in Turkey, delivered between 2001 and 2009, this study identifies the ministers’ priorities for tourism and compares them with the tourism policy objectives set out in Turkey's Tourism Strategic Action Plan. Further comparison is undertaken to see whether priorities changed within and between governments. The results of the content analysis indicate that the statements of the Turkish tourism ministers were economically driven and growth-oriented, and that there were inconsistencies between the ministers’ priorities and the co...

A discrete artificial bee colony algorithm for the traveling salesman problem with time windows

Abstract: This paper presents a discrete artificial bee colony algorithm (DABC) for solving the traveling salesman problem with time windows (TSPTW) in order to minimize the total travel cost of a given tour. TSPTW is a difficult optimization problem arising in both scheduling and logistic applications. The proposed DABC algorithm basically relies on the destruction and construction phases of iterated greedy algorithm to generate neighboring food sources in a framework of ABC algorithm. In addition, it also relies on a classical 1-opt local search algorithm to further enhance the solution quality. The performance of the algorithm was tested on a benchmark set from the literature. Experimental results show that the proposed DABC algorithm is very competitive to or even better than the best performing algorithms from the literature.

Capital Flows and Economic Growth across Spectral Frequencies: Evidence from Turkey

Abstract: This paper examines interactions and feedbacks between categories of capital flows and economic growth in Turkey for the 1992:01-2009:08 period. Our empirical analysis is based on a new version of the causality test of John Geweke (1982, p. 77) and Yuzo Hosoya (1991, p. 88) in the frequency domain proposed recently by Jorg Breitung and Bertrand Candelon (2006, p. 132). In addition, using standard methods in spectral analysis, we decompose the total covariance between capital flows and growth across main frequency bands and capture lead/lag interactions between them. Some of our findings are as follows: Variance decompositions over frequency bands reveal that variations in individual capital flow categories are largely concentrated over high (seasonal) frequencies. The nature of the interaction/feedback between growth and capital flows varies significantly over frequency bands and subcategories of flows. Over business cycle frequencies, two out of four subcategories of inflows, short-term external borrowings and portfolio investments on government bonds, drive growth whereas the other two components, long-term borrowings and portfolio investments on shares, are driven by growth. Furthermore, for the post-2001 financial crisis period we found significant bidirectional causality between long-term external borrowings and growth whereas portfolio investments, bond flows and short-term external borrowings do not affect growth in the long run. Key words: Capital flows, Causality in frequency domain, Geweke’s measure of feedback, Turkey.JEL: C32, F21, F32, F43.

User-driven automatic test-case generation for DTV/STB reliable functional verification

Abstract: In recent years Digital TV receivers (DTV) and Set- Top Boxes (STB) have been advancing in terms of new functionalities they offer to the end-users. This has mainly been triggered by the appearance of new multimedia formats and applications needed to be adequately handled by the DTV/STB. In such complex system within the environment consisting of wide range of non-interactive as well as interactive applications and services for television, internet, gamming, healthcare, surveillance, etc., efficient and reliable DTV functional verification becomes highly necessary and challenging task. Since efficient DTV testing is considered as one of the most important issues for the reduced time-to-market, its optimization is of crucial importance to the DTV manufacturing process. Having in mind the end-users as the main target of the DTV, optimal test generation process must also include estimated usage-profiles in addition to the pre-defined DTV designed specification. This is especially important considering new emerging multimedia technologies for DTV which are not yet fully standardized and evaluated, and which exact employment (from the point of end-users) is not known in advance. In this paper we propose a novel approach for user driven test-case generation that would enable adequate and efficient testing of the DTV/STB in different development stages before reaching the market, i.e., the end-users. The proposed user driven approach provides optimal test-case generation in terms of both test execution time and adequacy according to the real end-user DTV functional DTV operation and quality of experience (QoE). This is obtained by incorporating a novel design and selection scheme for test-cases generation based on the modeled end-users most required functional operations on the DTV/STB under test and its expectations of it.

Solving fuzzy job-shop scheduling problem by a hybrid PSO algorithm

Abstract: This paper proposes a hybrid particle swarm optimization (PSO) algorithm for solving the job-shop scheduling problem with fuzzy processing times. The objective is to minimize the maximum fuzzy completion time, i.e., the fuzzy makespan. In the proposed PSO-based algorithm performs global explorative search, while the tabu search (TS) conducts the local exploitative search. One-point crossover operator is developed for the individual to learn information from the other individuals. Experimental results on three well-known benchmarks and a randomly generated case verify the effectiveness and efficiency of the proposed algorithm.

Destination Management and Quality-of-Life

Abstract: Tourism is a very popular activity worldwide since it offers numerous opportunities to color up the tiring and boring lives of the human beings. It has been very hard to catch up with work, family, and social life since most of the people have to work due to economical burdens and the problems that arise day to day. The problems and the burdens urge people to take care of their health and level of stress so that tourism seems to be one of the most effective tools to keep away from the daily conflicts. This popular rise also brought new concepts and definitions to the literature which underlines the importance of life in terms of “quality” such as quality-of-life. However, it is evident that the interest of individuals in tourism caught the interests of the entrepreneurs, the interest of entrepreneurs accelerated the rivalry, and the rivalry brought the challenging and severe competition in several tourism destinations. This competitiveness not only caused a high increase in terms of revenues and infrastructural developments in destinations but also it caused remaining negative effects which seemed to be affecting the quality-of-life. This chapter highlights the interaction between the competitiveness of the tourism destinations and the quality-of-life. The importance of destination management and marketing are also underlined with regard to close relationship between these two phenomena.

Foreign Equity Trading and Average Stock-Return Volatility

Abstract: We examine whether there is a relationship between foreign equity trading and average total volatility, measured as the value-weighted average of stock-return variances in the Istanbul Stock Exchange. We employ foreign equity purchase and sale data to track changes in foreign equity trading, which not only enable us to capture effective foreign investor participation but also to observe the potential asymmetric effects of incoming and outgoing funds on the average total volatility. Consistent with the implications of the asymmetric information hypothesis, we find that net equity flow is positively associated with average total volatility. Furthermore, we show that net equity flow affects the average total volatility through the local and idiosyncratic volatilities, suggesting that foreign investors engage in firm-specific and market-wide information production.

Theoretical and Empirical Review of Asset Pricing Models: A Structural Synthesis

Abstract: The purpose of this paper is to give a comprehensive theoretical review devoted to asset pricing models by emphasizing static and dynamic versions in the line with their empirical investigations. A considerable amount of financial economics literature devoted to the concept of asset pricing and their implications. The main task of asset pricing model can be seen as the way to evaluate the present value of the pay offs or cash flows discounted for risk and time lags. The difficulty coming from discounting process is that the relevant factors that affect the pay offs vary through the time whereas the theoretical framework is still useful to incorporate the changing factors into an asset pricing models. This paper fills the gap in literature by giving a comprehensive review of the models and evaluating the historical stream of empirical investigations in the form of structural empirical review. Keywords: Financial economics; Asset pricing; Static CAPM; Dynamic CAPM; Structural empirical review JEL Classifications: G00; G12; G13

Artificial Bee Colony Optimization Algorithm for Uncapacitated Facility Location Problems

Abstract: In this paper, a new multiple facility location an d allocation method is proposed. This algorithm assigns demand points to p re-determined facilities which have infinite capacities, by using an artificial be e colony optimization with local search to solve discrete uncapacitated multiple fac ility location problems. This method is tested and compared with continuous and discrete particle swarm optimization based facility location methods on alt ernative models with or without local search for optimizing the well-known benchmark problems and generated problems.Similar test is conducted on actual demand and transportation cost data from a fertilizer manufacturer from Turkey, which i ncludes 11 facility locations and 768 demand points. Proposed ABC-based algorithm exhibited better performance than the PSO-based algorithms.

Public relations in a time of turbulence: A study on Turkish PR firms

Abstract: 2008 global economic crisis affected many companies. In order to survive and to become more competitive in today's turbulent business world, companies took drastic actions to gain cost reduction from every part of their business. Turkey, having been experienced a bigger crisis in 2001 and developed many models to manage the situation until 2008, is accepted as being more precautious than other countries. Still, Turkish public relations (PR) firms have been subjected to many changes, particularly advances in communication technologies, which have forced PR firms to restructure their organizations and adapt to new business models. The main purpose of our research is to gain insight on how Turkish PR firms adapted to the time of turbulence. Our research is based on qualitative data obtained from leading PR firms that are the members of ICCO representative IDA (Communication Consultancy Companies Association) in Turkey.

Improving performance of ACO algorithms using crossover mechanism based on mean of pheromone tables

Abstract: Ant Colony Optimization (ACO) Algorithms have been used to solve many optimization problems in various fields and several algorithms have been proposed based on ACO metaheuristic in the literature. This paper proposes a simple crossover mechanism based on mean of pheromone tables for ACO algorithms. Main purpose of the crossover operation is to produce solutions or individuals having greater performance than their parents by selecting useful parts. Original ACO Algorithms don't have crossover. Method that we developed employs more than one ant colonies and also solutions. Suitable low-cost average based operations are then applied to pheromone tables obtained after several iterations as crossover operator. Algorithm is tested on Traveling Salesman Problem using some benchmark problems from TSPLIB and results are presented. Our experiments and comparisons show that crossover mechanism improves the performance of ACO Algorithms.

Stochastic maximum principle for switching systems

Abstract: This paper provides necessary conditions of optimality, in the form of a maximum principle, for optimal control problems of switching systems Dynamics of the constituent processes take the form of stochastic differential equations with control terms in the drift and diffusion coefficients The restrictions on the transitions or switches between operating modes, are described by collections of functional equality constraints

A discrete harmony search algorithm for the economic lot scheduling problem with power of two policy

Abstract: In this paper, we present a problem specific discrete harmony search (DHS) algorithms to solve the economic lot scheduling problem (ELSP) under the extended basic period (EBP) approach and power-of-two (PoT) policy. In particular, DHS algorithms generate a cyclic production schedule, consisting of n items to be produced on a single machine, where the production cycle of each item is an integer multiple of a fundamental cycle. All the integer multipliers take the form of PoT which restricts the search space but provides good solution qualities. Under the EBP approach, feasibility is guaranteed with a constraint checking whether or not the items assigned in each period can be produced within the length of the period. For this restricted problem, which is still NP-hard, the proposed DHS algorithms employ a multi-chromosome solution representation to encode power-of-two multipliers and the production positions separately. Both feasible and infeasible solutions are maintained in the population through the use of some sophisticated constraint handling methods. A variable neighborhood search (VNS) algorithm is also hybridized with DHS algorithms to further enhance the solution quality. The experimental results show that the proposed algorithms are very competitive to the best performing algorithms from the existing literature under the EBP and PoT policy

Real-time kd-tree based importance sampling of environment maps

Abstract: We present a new real-time importance sampling algorithm for environment maps. Our method is based on representing environment maps using kd-tree structures, and generating samples with a single data lookup. An efficient algorithm has been developed for real-time image-based lighting applications. In this paper, we compared our algorithm with Inversion method [Fishman 1996]. We show that our proposed algorithm provides compactness and speedup as compared to Inversion method. Based on a number of rendered images, we have demonstrated that in a fixed time frame the proposed algorithm produces images with a lower noise than that of the Inversion method. We also demonstrate that our algorithm can successfully represent a wide range of material types.

Socio-Cultural Approaches to Tourism: A Research on the “Tourist” Notion of Young Turkish People

Abstract: Significance of tourism sector in Turkey is constantly expanding. Correspondingly the importance of the economic and socio-cultural impact of tourism also continues to develop. Because tourism draws tourists get into closer contact with the locals it has positive and negative effects on the destination. In general the aim of tourists is satisfying their expectations at the maximum degree during their stay. On the other side locals who live and work in the destination region have a primary role in welcoming them and satisfying the tourists’ needs and expectation. Turkish society is particularly well known for many generations as being very hospitable. Current research aims to reveal whether the young Turkish people sustain traditional “Turkish Hospitality” and to see their thoughts about tourists. The field research has been conducted on students of a foundation university located in Izmir and these young people’s point of view on tourists has been investigated by face to face interviews. It has been concluded that there is a weakening trend, nevertheless the notion of hospitality remains.

Omitted variable bias and detection with reset test in regression analysis

Abstract: In this paper, it is aimed to investigate the omitted variable bias, its importance, reasons, and consequences and to research the methods for dealing with omitted variable bias and RESET test which is a method for detecting omitted variable(s). A simulation was performed and three types of populations which varied depending on the correlations between the variables were generated and random samples were drawn from these populations. When correlations were changed and the number of omitted variables was increased, the effects of omitted variable bias were investigated. Moreover, by increasing the sample size, it was investigated whether the effects of omitted variable bias were changed depending on sample size