Now showing items 1-20 of 66

  • A characterization of totally umbilical hypersurfaces of a space form by geodesic mapping 

    Authors:Canfes, Elif Ozkara; Özdeǧer, Abdülkadir
    Publisher and Date:(Springer, 2013)
    The idea of considering the second fundamental form of a hypersurface as the first fundamental form of another hypersurface has found very useful applications in Riemannian and semi-Riemannian geometry especially when trying to characterize extrinsic hyperspheres and ovaloids. Recently T. Adachi and S. Maeda gave a characterization of totally umbilical hypersurfaces in a space form by circles. In our paper we give a characterization of totally umbilical hypersurfaces of a space form by means of ...

  • A comparison of fluorescence and UV-visible spectrometry techniques for thermal phase transitions of agarose gels 

    In this study thermoreversible phase transitions of high (HMP) and low (LMP) melting point agarose gels were investigated by using the UV-vis and fluorescence spectroscopy techniques. Pyranine was added to the aqueous solution of agarose as a fluorescence-probe. Transmitted light (I (tr)) and fluorescence emission (I (fl)) intensities from the gel samples with different agarose concentrations were monitored during the heating (gel-sol) and cooling (sol-gel) processes. For the both techniques gel-sol ...

  • A fuzzy AHP approach to evaluating machine tool alternatives 

    Authors:Ayaǧ, Zeki; Özdemir, Rifat Gürcan
    Publisher and Date:(Springer, 2006)
    Selecting process of a machine tool has been very important issue for companies for years because the improper selection of a machine tool might cause of many problems affecting negatively on productivity precision flexibility and company's responsive manufacturing capabilities. On the other hand selecting the best machine tool from its increasing number of existing alternatives in market are multiple-criteria decision making (MCDM) problem in the presence of many quantitative and qualitative ...

  • A Fuzzy AHP-TOPSIS-Based Group Decision-Making Approach to IT Personnel Selection 

    Global competition and the rapid development of information technologies force organizations to continuously change their ways. Nowadays organizations need personnel who make a difference through innovative ideas and who keep up with the rapid changes. In this paper the personnel selection process in a Turkish dairy company's information technology (IT) department is discussed as a group multi-criteria decision-making problem. The main purpose of the paper is to select the best employee candidate ...

  • A fuzzy QFD approach to determine supply chain management strategies in the dairy industry 

    Authors:Ayaǧ, Zeki; Samanlıoğlu, Funda; Büyükozkan, Gülçin
    Publisher and Date:(Springer, 2013)
    The aim of this study is to identify the crucial logistics requirements and supply chain management (SCM) strategies for the dairy industry. For product or service development quality function deployment (QFD) is a useful approach to maximize customer satisfaction. The determination of design requirements and supply chain management strategies are important issues during QFD processes for product or service design. For this reason a fuzzy QFD methodology is proposed in this study to determine these ...

  • A mechanism design approach to allocating central government funds among regional development agencies 

    Authors:Kıbrıs, Özgür; Tapkı, İpek Gürsel
    Publisher and Date:(Springer, 2014)
    To allocate central government funds among regional development agencies we look for mechanisms that satisfy three important criteria: efficiency (individual and coalitional) strategy proofness (a.k.a. dominant strategy incentive compatibility) and fairness. We show that only a uniform mechanism satisfies all three. We also show that all efficient and strategy proof mechanisms must function by assigning budget sets to the agencies and letting them freely choose their optimal bundle. In choosing ...

  • A Pseudo-Pareto Distribution and Concomitants of Its Order Statistics 

    Authors:Gebizlioǧlu, Ömer Lütfi; Yorubulut, Serap
    Publisher and Date:(Springer, 2016)
    Pareto distributions are very flexible probability models with various forms and kinds. In this paper a new bivariate Pseudo-Pareto distribution and its properties are presented and discussed. Main variables order statistics and concomitants of this distribution are studied and their importance for risk and reliability analysis is explained. Joint and marginal distributions complementing cumulative distributions and hazard functions of the variables are derived. Numerical illustrations graphical ...

  • A Software Component Architecture for Adaptive and Predictive Rate Control of Video Streaming 

    Authors:Arsan, Taner; Saydam, Tuncay
    Publisher and Date:(Springer, 2008)
    Quality of Service and Transmission Rate Optimization in live and on-demand video streaming is a very important issue in lossy IP networks. Infrastructure of the Internet exhibits variable bandwidths delays congestions and time-varying packet losses. Because of such attributes video streaming applications should not only have good end-to-end transport layer performance but also a robust rate control optimization mechanisms. This paper gives an overview of video streaming applications and proposal ...

  • Amplitude and Frequency Modulations with Cellular Neural Networks 

    Authors:Tander, Baran; Özmen, Atilla
    Publisher and Date:(Springer, 2015)
    Amplitude and frequency modulations are still the most popular modulation techniques in data transmission at telecommunication systems such as radio and television broadcasting gsm etc. However the architectures of these individual systems are totally different. In this paper it is shown that a cellular neural network with an opposite-sign template can behave either as an amplitude or a frequency modulator. Firstly a brief information about these networks is given and then the amplitude and frequency ...

  • An integrated approach to concept evaluation in a new product development 

    Authors:Ayaǧ, Zeki
    Publisher and Date:(Springer, 2016)
    A new product development (NPD) process can be thought as a comprehensive process in which the design is progressively detailed through a series of phases. At the end of each phase a design review is held to approve the design and release or not it to the next level. As one of these phases concept selection aiming to select the most appropriate concept for further development is conducted earlier in the process. As the further development progresses on a selected concept it becomes more difficult ...

  • An intelligent approach to machine tool selection through fuzzy analytic network process 

    Authors:Ayaǧ, Zeki; Özdemir, Rıfat Gürcan
    Publisher and Date:(Springer, 2011)
    In this study we utilize analytic network process (ANP) a more general form of AHP for justifying stand-alone machine tools out of available alternatives in market due to the fact that AHP cannot accommodate the variety of interactions dependencies and feedback between higher and lower level elements. However due to the vagueness and uncertainty on judgments of a decision-maker the crisp pair wise comparison in the conventional ANP seems to be insufficient and imprecise to capture the right judgments ...

  • An intelligent approach to supplier evaluation in automotive sector 

    Authors:Ayaǧ, Zeki; Samanlıoğlu, Funda
    Publisher and Date:(Springer, 2016)
    During the process of supplier evaluation selecting the best desirable supplier is one of the most critical problems of companies since improperly selected suppliers may cause losing time cost and market share of a company. For this multiple-criteria decision making selection problem in this paper a fuzzy extension of analytic network process (ANP) which uses uncertain human preferences as input information in the decision-making process is applied since conventional methods such as analytic ...

  • Antecedents and performance outcomes of value-based selling in sales teams: a multilevel, systems theory of motivation perspective 

    Firms are increasingly deploying a value-based selling (VBS) approach in their sales organizations to drive growth for new offerings. However, VBS adoption remains challenging, signaling that leaders need guidance to motivate VBS. Drawing from the systems theory of motivation, we examine motivational mechanisms at two levels-salesperson and sales team-to understand how to motivate, and benefit from, VBS. Using multisource data (i.e., salespeople, managers, archival performance) from 70 sales teams ...

  • Art investment: hedging or safe haven through financial crises 

    Authors:Öztürkkal, Belma; Toğan-Eğrican, Aslı
    Publisher and Date:(Springer, 2020)
    We analyze long-term art auction sales data focusing on and around financial crisis periods with other investment returns to understand whether art can be considered a safe haven during volatile times or a hedging option in general by analyzing art auction data in a volatile emerging market. Our findings suggest Turkish art returns are either negatively correlated or at low correlation with other investments, including the equity market. We have the view that art can be considered a hedging mechanism ...

  • Assessing protein-ligand binding modes with computational tools: the case of PDE4B 

    In a first step in the discovery of novel potent inhibitor structures for the PDE4B family with limited side effects we present a protocol to rank newly designed molecules through the estimation of their IC values. Our protocol is based on reproducing the linear relationship between the logarithm of experimental IC values [(IC)] and their calculated binding free energies (). From 13 known PDE4B inhibitors we show here that (1) binding free energies obtained after a docking process by AutoDock are ...

  • Bayesian compressive sensing for ultra-wideband channel estimation: algorithm and performance analysis 

    Authors:Özgör, Mehmet; Erküçük, Serhat; Çırpan, Hakan Ali
    Publisher and Date:(Springer, 2015)
    Due to the sparse structure of ultra-wideband (UWB) channels compressive sensing (CS) is suitable for UWB channel estimation. Among various implementations of CS the inclusion of Bayesian framework has shown potential to improve signal recovery as statistical information related to signal parameters is considered. In this paper we study the channel estimation performance of Bayesian CS (BCS) for various UWB channel models and noise conditions. Specifically we investigate the effects of (i) sparse ...

  • Between anchors and aspirations: a new family of bargaining solutions 

    Authors:Karagözoğlu, Emin; Keskin, Kerim; Özcan-Tok, Elif
    Publisher and Date:(Springer, 2019)
    We study the salience and power of reference points in determining the effective anchors and aspirations in bargaining problems. Along this line we enrich the analysis of the standard bargaining model with two new parameters: the first parameter can be interpreted as the effectiveness (or salience) of the reference point in determining the anchor whereas the second parameter can be interpreted as its effectiveness in shaping agents' aspirations. Utilizing these parameters we provide a unifying ...

  • Channel Estimation for Realistic Indoor Optical Wireless Communication in ACO-OFDM Systems 

    Authors:Özmen, Atilla; Şenol, Habib
    Publisher and Date:(Springer, 2018)
    In this paper channel estimation problem in a visible light communication system is considered. The information data is transmitted using asymmetrical clipped optical orthogonal frequency division multiplexing. Channel estimation and symbol detection are performed by the Maximum Likelihood and the Linear Minimum Mean Square Error detection techniques respectively. The system performance is investigated in realistic environment that is simulated using an indoor channel model. Two different channels ...

  • A Competitive Intelligence Practices Typology in an Airline Company in Turkey 

    Authors:Şahin, Murat; Bisson, Christophe
    Publisher and Date:(Springer, 2020)
    Oil prices, political instabilities, travel legislations, and many other competitive factors make it essential for any international airline with the instinct to survive to be on constant watch in such a fiercely competitive environment. To meet this need, it is vital for international airline companies to integrate competitive intelligence (CI) into their strategy building process. In this study, we create for the first time a typology of competitive intelligence practices of an international ...

  • Controlling the growth of particle size and size distribution of silica nanoparticles by the thin film structure 

    Authors:Uysal, Bengü Özuǧur; Tepehan, Fatma Zehra
    Publisher and Date:(Springer, 2012)
    Nanostructured silicondioxide thin films were prepared by sol-gel spin coating technique. The SiO2 films were made using a conventional mixture of tetraethoxysilane (TEOS) deionized water and ethanol with various NH3/TEOS ratios. The nanostructured silica films were made using a mixture of the SiO2 sol and regular SiO2 sol to control the enlargement of the particles inside the films. The structural morphological and optical characterizations of the as-deposited and annealed films were carried out ...