• Title/Summary/Keyword: Darboux vector

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CHARACTERIZATIONS OF SPACE CURVES WITH 1-TYPE DARBOUX INSTANTANEOUS ROTATION VECTOR

  • Arslan, Kadri;Kocayigit, Huseyin;Onder, Mehmet
    • Communications of the Korean Mathematical Society
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    • v.31 no.2
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    • pp.379-388
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    • 2016
  • In this study, by using Laplace and normal Laplace operators, we give some characterizations for the Darboux instantaneous rotation vector field of the curves in the Euclidean 3-space $E^3$. Further, we give necessary and sufficient conditions for unit speed space curves to have 1-type Darboux vectors. Moreover, we obtain some characterizations of helices according to Darboux vector.

PARAMETRIC EQUATIONS OF SPECIAL CURVES LYING ON A REGULAR SURFACE IN EUCLIDEAN 3-SPACE

  • El Haimi, Abderrazzak;Chahdi, Amina Ouazzani
    • Nonlinear Functional Analysis and Applications
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    • v.26 no.2
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    • pp.225-236
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    • 2021
  • In this paper, we determine position vector of a line of curvature of a regular surface which is relatively normal-slant helix, with respect to Darboux frame. Then, a vector differential equation is established by means Darboux formulas, in the case of the geodesic torsion is vanishes. In terms of solution, we determine the parametric representation of a line of curvature which is relatively normal-slant helix, with respect to standard frame in Euclidean 3-space. Thereafter, we apply this result to find the position vector of a line of curvature which is isophote curve.

A NEW MODELLING OF TIMELIKE Q-HELICES

  • Yasin Unluturk ;Cumali Ekici;Dogan Unal
    • Honam Mathematical Journal
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    • v.45 no.2
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    • pp.231-247
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    • 2023
  • In this study, we mean that timelike q-helices are curves whose q-frame fields make a constant angle with a non-zero fixed axis. We present the necessary and sufficient conditions for timelike curves via the q-frame to be q-helices in Lorentz-Minkowski 3-space. Then we find some results of the relations between q-helices and Darboux q-helices. Furthermore, we portray Darboux q-helices as special curves whose Darboux vector makes a constant angle with a non-zero fixed axis by choosing the curve as one of the types of q-helices, and also the general case.

SOME GEOMERTIC SOLVABILITY THEOREMS IN TOPOLOGICAL VECTOR SPACES

  • Ben-El-Mechaiekh, H.;Isac, G.
    • Bulletin of the Korean Mathematical Society
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    • v.34 no.2
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    • pp.273-285
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    • 1997
  • The aim of this paper is to present theorems on the exitence of zeros for mappings defined on convex subsets of topological vector spaces with values in a vector space. In addition to natural assumptions of continuity, convexity, and compactness, the mappings are subject to some geometric conditions. In the first theorem, the mapping satisfies a "Darboux-type" property expressed in terms of an auxiliary numerical function. Typically, this functions is, in this case, related to an order structure on the target space. We derive an existence theorem for "obtuse" quasiconvex mappings with values in an ordered vector space. In the second theorem, we prove the existence of a "common zero" for an arbitrary (not necessarily countable) family of mappings satisfying a general "inwardness" condition againg expressed in terms of numerical functions (these numerical functions could be duality pairings (more generally, bilinear forms)). Our inwardness condition encompasses classical inwardness conditions of Leray-Schauder, Altman, or Bergman-Halpern types.

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