scholarly journals Geometric Characterizations of Canal Surfaces in Minkowski 3-Space II

Mathematics ◽  
2019 ◽  
Vol 7 (8) ◽  
pp. 703 ◽  
Author(s):  
Jinhua Qian ◽  
Mengfei Su ◽  
Xueshan Fu ◽  
Seoung Dal Jung
Keyword(s):  
Gaussian Curvature ◽  
Mean Curvature ◽  
Space Curve ◽  
Timelike Curve ◽  
Geometric Properties ◽  
Spacelike Curve ◽  
Space Curves ◽  
Canal Surfaces ◽  
The Mean ◽  
The Relationship

Canal surfaces are defined and divided into nine types in Minkowski 3-space E 1 3 , which are obtained as the envelope of a family of pseudospheres S 1 2 , pseudohyperbolic spheres H 0 2 , or lightlike cones Q 2 , whose centers lie on a space curve (resp. spacelike curve, timelike curve, or null curve). This paper focuses on canal surfaces foliated by pseudohyperbolic spheres H 0 2 along three kinds of space curves in E 1 3 . The geometric properties of such surfaces are presented by classifying the linear Weingarten canal surfaces, especially the relationship between the Gaussian curvature and the mean curvature of canal surfaces. Last but not least, two examples are shown to illustrate the construction of such surfaces.

scholarly journals Umbilical points on surfaces in RN

1985 ◽  
Vol 100 ◽  
pp. 135-143 ◽  
Author(s):  
Kazuyuki Enomoto
Keyword(s):  
Gaussian Curvature ◽  
Mean Curvature ◽  
Curvature Vector ◽  
Mean Curvature Vector ◽  
Normal Connection ◽  
Round Sphere ◽  
Positive Gaussian Curvature ◽  
Connected Surface ◽  
Umbilical Points ◽  
The Mean

Let ϕ: M → RN be an isometric imbedding of a compact, connected surface M into a Euclidean space RN. ψ is said to be umbilical at a point p of M if all principal curvatures are equal for any normal direction. It is known that if the Euler characteristic of M is not zero and N = 3, then ψ is umbilical at some point on M. In this paper we study umbilical points of surfaces of higher codimension. In Theorem 1, we show that if M is homeomorphic to either a 2-sphere or a 2-dimensional projective space and if the normal connection of ψ is flat, then ψ is umbilical at some point on M. In Section 2, we consider a surface M whose Gaussian curvature is positive constant. If the surface is compact and N = 3, Liebmann’s theorem says that it must be a round sphere. However, if N ≥ 4, the surface is not rigid: For any isometric imbedding Φ of R3 into R4 Φ(S2(r)) is a compact surface of constant positive Gaussian curvature 1/r2. We use Theorem 1 to show that if the normal connection of ψ is flat and the length of the mean curvature vector of ψ is constant, then ψ(M) is a round sphere in some R3 ⊂ RN. When N = 4, our conditions on ψ is satisfied if the mean curvature vector is parallel with respect to the normal connection. Our theorem fails if the surface is not compact, while the corresponding theorem holds locally for a surface with parallel mean curvature vector (See Remark (i) in Section 3).

scholarly journals On the second Gaussian curvature of ruled surfaces in Euclidean $3$-space

2006 ◽  
Vol 37 (3) ◽  
pp. 221-226 ◽  
Author(s):  
Dae Won Yoon
Keyword(s):  
Euclidean Space ◽  
Gaussian Curvature ◽  
Mean Curvature ◽  
Ruled Surface ◽  
Ruled Surfaces ◽  
Dimensional Euclidean Space ◽  
3 Dimensional ◽  
The Mean ◽  
Second Gaussian Curvature

In this paper, we mainly investigate non developable ruled surface in a 3-dimensional Euclidean space satisfying the equation $K_{II} = KH$ along each ruling, where $K$ is the Gaussian curvature, $H$ is the mean curvature and $K_{II}$ is the second Gaussian curvature.

scholarly journals Weingarten and Linear Weingarten Type Tubular Surfaces in

2011 ◽  
Vol 2011 ◽  
pp. 1-11 ◽  
Author(s):  
Yılmaz Tunçer ◽  
Dae Won Yoon ◽  
Murat Kemal Karacan
Keyword(s):  
Gaussian Curvature ◽  
Mean Curvature ◽  
The Mean ◽  
Second Gaussian Curvature ◽  
Tubular Surfaces

We study tubular surfaces in Euclidean 3-space satisfying some equations in terms of the Gaussian curvature, the mean curvature, the second Gaussian curvature, and the second mean curvature. This paper is a completion of Weingarten and linear Weingarten tubular surfaces in Euclidean 3-space.

scholarly journals Offset Ruled Surface in Euclidean Space with Density

2021 ◽  
Vol 29 (1) ◽  
pp. 219-233
Author(s):  
Neslihan Ulucan ◽  
Mahmut Akyigit
Keyword(s):  
Euclidean Space ◽  
Gaussian Curvature ◽  
Mean Curvature ◽  
Ruled Surface ◽  
Ruled Surfaces ◽  
Surfaces In Euclidean Space ◽  
The Mean

Abstract In this paper, offset ruled surfaces in these spaces are defined by using the geometry of ruled surfaces in Euclidean space with density. The mean curvature and Gaussian curvature of these surfaces are studied. In addition, the relationships between the mean curvature and mean curvature with density, and the Gaussian curvature and the Gaussian curvature with density of the offset ruled surfaces in E 3 with density e z and e − x 2− y 2 are given.

Rail Geometry and Euler Angles

2006 ◽  
Vol 1 (3) ◽  
pp. 264-268 ◽  
Author(s):  
Cheta Rathod ◽  
Ahmed A. Shabana
Keyword(s):  
Vehicle Dynamics ◽  
Euler Angles ◽  
Frenet Frame ◽  
Geometric Properties ◽  
Track Geometry ◽  
Railroad Vehicle Dynamics ◽  
Space Curves ◽  
Curvature And Torsion ◽  
The Relationship ◽  
Railroad Vehicle

In railroad vehicle dynamics, Euler angles are often used to describe the track geometry (track centerline and rail space curves). The tangent and curvature vectors as well as local geometric properties such as the curvature and torsion can be expressed in terms of Euler angles. Some of the local geometric properties and Euler angles can be related to measured parameters that are often used to define the track geometry. The Euler angles employed, however, define a coordinate system that may differ from the Frenet frame used in the classical differential geometry. The relationship between the track frame used in railroad vehicle dynamics and the Frenet frame used in the theory of curves is developed in this paper and is used to shed light on some of the formulas and identities used in the geometric description in railroad vehicle dynamics. The conditions under which the two frames (track and Frenet) become equivalent are presented and used to obtain expressions for the curvature and torsion in terms of Euler angles and their derivatives with respect to the arc length.

scholarly journals 3D Palmprint Recognition Using Dempster-Shafer Fusion Theory

2015 ◽  
Vol 2015 ◽  
pp. 1-7 ◽  
Author(s):  
Jianyun Ni ◽  
Jing Luo ◽  
Wubin Liu
Keyword(s):  
Gaussian Curvature ◽  
Mean Curvature ◽  
Imaging Technique ◽  
Recognition Performance ◽  
Belief Function ◽  
Recognition Algorithm ◽  
Palmprint Recognition ◽  
Equal Error Rate ◽  
The Mean ◽  
Fusion Theory

This paper proposed a novel 3D palmprint recognition algorithm by combining 3D palmprint features using D-S fusion theory. Firstly, the structured light imaging is used to acquire the 3D palmprint data. Secondly, two types of unique features, including mean curvature feature and Gaussian curvature feature, are extracted. Thirdly, the belief function of the mean curvature recognition and the Gaussian curvature recognition was assigned, respectively. Fourthly, the fusion belief function from the proposed method was determined by the Dempster-shafer (D-S) fusion theory. Finally, palmprint recognition was accomplished according to the classification criteria. A 3D palmprint database with 1000 range images from 100 individuals was established, on which extensive experiments were performed. The results show that the proposed method 3D palmprint recognition is much more robust to illumination variations and condition changes of palmprint than MCR and GCR. Meanwhile, by fusing mean curvature and Gaussian curvature feature, the experimental results are promising (the average equal error rate of 0.404%). In the future, imaging technique needs further improvement for a better recognition performance.

scholarly journals The Gauss Map and the Third Laplace-Beltrami Operator of the Rotational Hypersurface in 4-Space

Symmetry ◽  
2018 ◽  
Vol 10 (9) ◽  
pp. 398 ◽  
Author(s):  
Erhan Güler ◽  
Hasan Hacısalihoğlu ◽  
Young Kim
Keyword(s):  
Gaussian Curvature ◽  
Mean Curvature ◽  
Gauss Map ◽  
Beltrami Operator ◽  
The Third ◽  
The Mean

We study and examine the rotational hypersurface and its Gauss map in Euclidean four-space E 4 . We calculate the Gauss map, the mean curvature and the Gaussian curvature of the rotational hypersurface and obtain some results. Then, we introduce the third Laplace–Beltrami operator. Moreover, we calculate the third Laplace–Beltrami operator of the rotational hypersurface in E 4 . We also draw some figures of the rotational hypersurface.

Accurate Representation of the Rail Geometry for Multibody System Applications

2009 ◽  
Vol 5 (1) ◽  
Author(s):  
Brian Marquis ◽  
Khaled E. Zaazaa ◽  
Tariq Sinokrot ◽  
Ahmed A. Shabana
Keyword(s):  
Space Curve ◽  
Contact Forces ◽  
Railway Track ◽  
Bank Angle ◽  
Space Curves ◽  
The Right ◽  
Yaw Angle ◽  
Horizontal Curvature ◽  
The Relationship

The objective of this study is to examine the geometric description of the spiral sections of railway track systems, in order to correctly define the relationship between the geometry of the right and left rails. The geometry of the space curves that define the rails are expressed in terms of the geometry of the space curve that defines the track center curve. Industry inputs such as the horizontal curvature, grade, and superelevation are used to define the track centerline space curve in terms of Euler angles. The analysis presented in this study shows that, in the general case of a spiral, the profile frames of the right and left rails that have zero yaw angles with respect to the track frame have different orientations. As a consequence, the longitudinal tangential creep forces acting on the right and left wheels, in the case of zero yaw angle, are not in the same direction. Nonetheless, the orientation difference between the profile frames of the right and left rails can be defined in terms of a single pitch angle. In the case of small bank angle that defines the superelevation of the track, one can show that this angle directly contributes to the track elevation. The results obtained in this study also show that the right and left rail longitudinal tangents can be parallel only in the case of a constant horizontal curvature. Since the spiral is used to connect track segments with different curvatures, the horizontal curvature cannot be assumed constant, and as a consequence, the right and left rail longitudinal tangents cannot be considered parallel in the spiral region. Numerical examples that demonstrate the effect of the errors that result from the assumption that the right and left rails in the spiral sections have the same geometry are presented. The numerical results obtained show that these errors can have a significant effect on the quality of the predicted creep contact forces.

Rail Geometry and Euler Angles

2006 ◽  
Author(s):  
Cheta M. Rathod ◽  
Ahmed A. Shabana
Keyword(s):  
Vehicle Dynamics ◽  
Euler Angles ◽  
Frenet Frame ◽  
Geometric Properties ◽  
Track Geometry ◽  
Railroad Vehicle Dynamics ◽  
Space Curves ◽  
Curvature And Torsion ◽  
The Relationship ◽  
Railroad Vehicle

In railroad vehicle dynamics, Euler angles are often used to describe the track geometry (track centerline and rail space curves). The tangent and curvature vectors as well as local geometric properties such as the curvature and torsion can be expressed in terms of Euler angles. Some of the local geometric properties and Euler angles can be related to measured parameters that are often used to define the track geometry. The Euler angles employed, however, define a coordinate system that may differ from the Frenet frame used in the classical differential geometry. The relationship between the track frame used in railroad vehicle dynamics and the Frenet frame used in the theory of curves is developed in this paper and used to shed light on some of the formulas and identities used in the geometric description in railroad vehicle dynamics. The conditions under which the two frames (track and Frenet) become equivalent are presented and used to obtain expressions for the curvature and torsion in terms of Euler angles and their derivatives with respect to the arc length.

scholarly journals TUBULAR SURFACES WITH DARBOUX FRAME IN GALILEAN 3-SPACE

2019 ◽  
pp. 253
Author(s):  
Sezai Kızıltuğ ◽  
Mustafa Dede ◽  
Cumali Ekici
Keyword(s):  
Gaussian Curvature ◽  
Mean Curvature ◽  
Frenet Frame ◽  
Darboux Frame ◽  
Tubular Surface ◽  
The Mean ◽  
Tubular Surfaces

In this paper, we define tubular surface by using a Darboux frame instead of a Frenet frame. Subsequently, we compute the Gaussian curvature and the mean curvature of the tubular surface with a Darboux frame. Moreover, we obtain some characterizations for special curves on this tubular surface in a Galilean 3-space.

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