Toplam kayıt 16, listelenen: 1-16

    • An alternative approach to determination of Covid‑19 personal risk index by using fuzzy logic 

      Şimşek, Hakan; Yangın, Elifnaz (Health and Techonology, 2022)
      COVID-19 disease is an outbreak that seriously affected the whole world, occurred in December 2019, and thus was declared a global epidemic by WHO (World Health Organization). To reduce the impact of the epidemic on humans, ...
    • Bäcklund’s theorem for n dimensional lorentzian submanifold in the minkowski space 𝔼21𝑛−1 

      Şimşek, Hakan; Özdemir, Mustafa (Results in Mathematics, 2016)
      In this paper, Bäcklund’s Theorem is introduced on the Lorentzian n-submanifold of the Minkowski space 𝔼2𝑛−11 by using the method of moving frames. Also, we prove the Integrability Theorem for the Lorentzian n-submanifold ...
    • Determining the customer satisfaction index for civil aviation organizations based on fuzzy logic and servqual method 

      Şimşek, Hakan; Güvendiren, İrem; Sarı, Şevval (International Capital Conference on Multidisciplinary Scientific Research, 2022)
      The aviation sector in Türkiye is one of the sectors with the highest growth rate. Competition in the aviation industry in recent years has greatly affected the activities of businesses. For businesses to survive in the ...
    • Determining the quality index of online shopping websites by using fuzzy logic 

      Şimşek, Hakan; Güvendiren, İrem (6th International New York Conference on Evolving Trends in Interdisciplinary Research and Practices, 2022)
      Online shopping is a platform of e-commerce allowing consumers to purchase goods or services directly from a seller over the Internet using a web browser or a mobile application. Due to Covid-19 pandemic, almost every ...
    • A fuzzy logic approach and path algorithm for time and energy management of smart cleaning robots 

      Şimşek, Hakan; Ertürk, Faize Nur; Şeker, Recep (2023)
      Smart home technologies (SHM) or devices provide some degree of digitally connected, automated, or enhanced services to building occupants in residential areas and have been becoming increasingly popular in recent years. ...
    • Generating hyperbolical rotation matrix for a given hyperboloid 

      Şimşek, Hakan; Özdemir, Mustafa (Linear Algebra and Its Applications, 2016)
      Hyperbolic rotation is hyperbolically the motion of a smooth object on general hyperboloids given by −a1x2+a2y2+a3z2=±λ, λ ∈R+. In this paper, we investigate the hyperbolical rotation matrices in order to get the motion ...
    • Healthy bread quality index based on food label information 

      Şimşek, Hakan; Sarı, Şevval (Elsevier, 2023)
      The label on the package shows important information such as the origin, type, price, and nutritional and energy value of the product during the purchase of the product. A decision support system is aimed at obtaining ...
    • On conformal curves in 2-dimensional de sitter space 

      Şimşek, Hakan; Özdemir, Mustafa (Advances in Applied Clifford Algebras, 2016)
      In this paper, we examine the pseudo-spherical curves, which are equivalent to each other under the conformal maps preserving a fixed point in the de Sitter 2-space, by using the Clifford algebra Cl 2,1. Also, we find the ...
    • On focal curves of null Cartan curves 

      Şimşek, Hakan (Turkish Journal of Mathematics, 2017)
      The focal curve, which is determined as the locus of centers of osculating pseudo-spheres of a null Cartan curve, is investigated in Minkowski (n+2)-space Mn+2. Moreover, a curve called acceleration focal curve of a null ...
    • On the eigenvalues and eigenvectors of a lorentzian rotation matrix by using split quaternions 

      Özdemir, Mustafa; Erdoğdu, Melek; Şimşek, Hakan (Advances in Applied Clifford Algebras, 2014)
      In this paper, we examine eigenvalue problem of a rotation matrix in Minkowski 3 space by using split quaternions. We express the eigenvalues and the eigenvectors of a rotation matrix in term of the coefficients of the ...
    • Rotations on a lightcone in minkowski 3-Space 

      Şimşek, Hakan; Özdemir, Mustafa (Advances in Applied Clifford Algebras, Springer, 2017)
      In this paper the generalization of the rotations on any lightcone in Minkowski 3-space ℝ1,2𝑔 is given. The rotation motion on the lightcone is examined by means of a bilinear form and Lorentzian notions. We use the ...
    • Shape curvatures of the Lorentzian plane curves 

      Şimşek, Hakan; Özdemir, Mustafa (Communications Faculty of Sciences University of Ankara Series A1 Mathematics and Statistics, 2017)
      In this paper, we examine the Lorentzian similar plane curvesusing the hyperbolic structure and spherical arc length parameter. We classifyall self-similar Lorentzian plane curves and give formulas for pseudo shapecurvatures ...
    • Similar and self-similar curves in minkowski n-space 

      Şimşek, Hakan; Özdemir, Mustafa (Bulletin of Korean Mathematical Society, 2015)
      In this paper, we investigate the similarity transformations in the Minkowski n-space. We study the geometric invariants of nonnull curves under the similarity transformations. Besides, we extend the fundamental theorem ...
    • Similar and self-similar null Cartan curves in Minkowski-Lorentzian spaces 

      Şimşek, Hakan (Communications Faculty of Sciences University of Ankara Series A1 Mathematics and Statistics, 2022)
      In this paper, differential invariants of null Cartan curves are studied in (n+2) dimensional Lorentzian similarity geometry. The fundamental theorem for a null Cartan curve in similarity geometry is investigated and the ...
    • Soft computing based e-commerce website service quality index measurement 

      Şimşek, Hakan; Güvendiren, İrem (Elsevier, 2023)
      It is observed that there is a need for a quality measurement template system that is easy to understand, effective, easily updated according to different requests, contains enough variables, and gives fast results, which ...
    • Some results on p-shape curvatures of non-lightlike space curves 

      Şimşek, Hakan; Özdemir, Mustafa (International Electronic Journal of Geometry, 2018)
      In this paper, we obtain some findings for a non-null curve parameterized by spherical arc length. We investigate the relationship between a non-null curve with p-shape curvatures and pseudospherical curves on S21 and ...