scholarly journals On a curvature flow in a band domain with unbounded boundary slopes

2021 ◽  
Vol 0 (0) ◽  
pp. 0
Author(s):  
Lixia Yuan ◽  
Wei Zhao
Keyword(s):  
Curvature Flow ◽  
Gradient Estimates ◽  
Normal Vector ◽  
Normal Velocity ◽  
Unit Normal Vector ◽  
Contact Points ◽  
Anisotropic Curvature ◽  
Robin Boundary ◽  
Zero Number ◽  
Boundary Slopes

<p style='text-indent:20px;'>This paper is devoted to an anisotropic curvature flow of the form <inline-formula><tex-math id="M1">\begin{document}$ V = A(\mathbf{n})H + B(\mathbf{n}) $\end{document}</tex-math></inline-formula> in a band domain <inline-formula><tex-math id="M2">\begin{document}$ \Omega : = [-1,1]\times {\mathbb{R}} $\end{document}</tex-math></inline-formula>, where <inline-formula><tex-math id="M3">\begin{document}$ \mathbf{n} $\end{document}</tex-math></inline-formula>, <inline-formula><tex-math id="M4">\begin{document}$ V $\end{document}</tex-math></inline-formula> and <inline-formula><tex-math id="M5">\begin{document}$ H $\end{document}</tex-math></inline-formula> denote respectively the unit normal vector, normal velocity and curvature of a graphic curve <inline-formula><tex-math id="M6">\begin{document}$ \Gamma_t $\end{document}</tex-math></inline-formula>. We require that the curve <inline-formula><tex-math id="M7">\begin{document}$ \Gamma_t $\end{document}</tex-math></inline-formula> contacts <inline-formula><tex-math id="M8">\begin{document}$ \partial \Omega $\end{document}</tex-math></inline-formula> with slopes equaling to the heights of the contact points (which corresponds to a kind of Robin boundary conditions). In spite of the unboundedness of the boundary slopes, we are able to obtain the <i>uniform interior gradient estimates</i> for the solutions by using the zero number argument. Furthermore, when <inline-formula><tex-math id="M9">\begin{document}$ t\to \infty $\end{document}</tex-math></inline-formula>, we show that <inline-formula><tex-math id="M10">\begin{document}$ \Gamma_t $\end{document}</tex-math></inline-formula> converges to a traveling wave with cup-shaped profile and <i>infinite</i> boundary slopes in the <inline-formula><tex-math id="M11">\begin{document}$ C^{2,1}_{\rm{loc}} ((-1,1)\times {\mathbb{R}}) $\end{document}</tex-math></inline-formula>-topology.</p>

Steklov eigenvalue problem with a-harmonic solutions and variable exponents

2020 ◽  
Vol 0 (0) ◽  
Author(s):  
Belhadj Karim ◽  
Abdellah Zerouali ◽  
Omar Chakrone
Keyword(s):  
Eigenvalue Problem ◽  
Smooth Boundary ◽  
Normal Vector ◽  
Variable Exponents ◽  
Variational Technique ◽  
Unit Normal Vector ◽  
Steklov Eigenvalue ◽  
Steklov Eigenvalue Problem ◽  
Outward Unit ◽  
Outward Unit Normal Vector

AbstractUsing the Ljusternik–Schnirelmann principle and a new variational technique, we prove that the following Steklov eigenvalue problem has infinitely many positive eigenvalue sequences:\left\{\begin{aligned} &\displaystyle\operatorname{div}(a(x,\nabla u))=0&&% \displaystyle\phantom{}\text{in }\Omega,\\ &\displaystyle a(x,\nabla u)\cdot\nu=\lambda m(x)|u|^{p(x)-2}u&&\displaystyle% \phantom{}\text{on }\partial\Omega,\end{aligned}\right.where {\Omega\subset\mathbb{R}^{N}}{(N\geq 2)} is a bounded domain of smooth boundary {\partial\Omega} and ν is the outward unit normal vector on {\partial\Omega}. The functions {m\in L^{\infty}(\partial\Omega)}, {p\colon\overline{\Omega}\mapsto\mathbb{R}} and {a\colon\overline{\Omega}\times\mathbb{R}^{N}\mapsto\mathbb{R}^{N}} satisfy appropriate conditions.

ENTIRE SOLUTIONS OF A CURVATURE FLOW IN AN UNDULATING CYLINDER

2018 ◽  
Vol 99 (1) ◽  
pp. 137-147
Author(s):  
LIXIA YUAN ◽  
BENDONG LOU
Keyword(s):  
Curvature Flow ◽  
Entire Solution ◽  
Travelling Wave ◽  
Normal Velocity ◽  
Two Dimensional ◽  
Entire Solutions ◽  
Smooth Functions ◽  
Periodic Traveling Waves ◽  
Periodic Travelling Wave ◽  
Positive Functions

We consider a curvature flow $V=\unicode[STIX]{x1D705}+A$ in a two-dimensional undulating cylinder $\unicode[STIX]{x1D6FA}$ described by $\unicode[STIX]{x1D6FA}:=\{(x,y)\in \mathbb{R}^{2}\mid -g_{1}(y)<x<g_{2}(y),y\in \mathbb{R}\}$, where $V$ is the normal velocity of a moving curve contacting the boundaries of $\unicode[STIX]{x1D6FA}$ perpendicularly, $\unicode[STIX]{x1D705}$ is its curvature, $A>0$ is a constant and $g_{1}(y),g_{2}(y)$ are positive smooth functions. If $g_{1}$ and $g_{2}$ are periodic functions and there are no stationary curves, Matano et al. [‘Periodic traveling waves in a two-dimensional cylinder with saw-toothed boundary and their homogenization limit’, Netw. Heterog. Media1 (2006), 537–568] proved the existence of a periodic travelling wave. We consider the case where $g_{1},g_{2}$ are general nonperiodic positive functions and the problem has some stationary curves. For each stationary curve $\unicode[STIX]{x1D6E4}$ unstable from above/below, we construct an entire solution growing out of it, that is, a solution curve $\unicode[STIX]{x1D6E4}_{t}$ which increases/decreases monotonically, converging to $\unicode[STIX]{x1D6E4}$ as $t\rightarrow -\infty$ and converging to another stationary curve or to $+\infty /-\infty$ as $t\rightarrow \infty$.

scholarly journals Design and Analysis of Posterior Semicircular Canal BPPV Diagnostic Test Based on Physical Simulation

2021 ◽  
Author(s):  
Xiaokai Yang ◽  
Qiancheng Yang ◽  
Zhaobang Liu
Keyword(s):  
Diagnostic Test ◽  
Semicircular Canal ◽  
Physical Simulation ◽  
Normal Vector ◽  
Forward Angle ◽  
Unit Normal Vector ◽  
Posterior Semicircular Canal ◽  
Average Value ◽  
Crista Ampullaris ◽  
Unit Normal

Abstract To discusses and analyzes how to realize the design of posterior semicircular canal BPPV diagnostic maneuver. First, measure the spatial attitude of the human semicircular canal, establish a BPPV virtual simulation platform, then analyze the key positions of the maneuver, and finally design a new diagnostic maneuver according to the demand, and perform physical simulation verification. The average value of the unit normal vector of the right posterior semicircular plane is [ 0.660, 0.702, 0.266], after rotate -46.8 ° around Z axis and 15.4 ° around Y axis, it parallel to the X axis. After that, when the tilt back angle reaches 70 °, the free otoconia in the left utricle will fall into the common crus; when bend forward 53.3°, the unit normal vector of the crista ampullaris plane of the posterior semicircular canal to the XY plane; when bend forward angle reaches 30°, the otoconia slides to the opening of the ampulla; when bend forward angle reaches 70°, the otoconia slides to the bottom of the crista ampullaris. The shallow pitching Yang maneuver is designed as turn head 45° to the one side, bend forward 45°, tilt back 90°, and bend forward 90°. The deep pitching Yang maneuver is designed as bend forward 90°, turn head 45° to one side, tilt back 135°, and bend forward 90°. A new posterior semicircular BPPV diagnostic test is designed to make the induced nystagmus have the characteristics of long latency, reversal, and repeatability, will not cause the inhibitory stimulation of the contralateral superior semicircular canal, and has good operation fault tolerance, which is of great value for clinical and scientific research.

Spaces and Operators

2012 ◽  
Author(s):  
G. F. Roach ◽  
I. G. Stratis ◽  
A. N. Yannacopoulos
Keyword(s):  
Normal Vector ◽  
Connected Component ◽  
Unit Normal Vector ◽  
Open Set ◽  
Outward Unit ◽  
Outward Unit Normal Vector ◽  
Unit Normal

This chapter consists mainly of definitions and various properties (without proofs) of spaces and operators used in this book. It defines O as an open set in Rᶰ such that it is locally on one side of its boundary Γ‎ := δ‎O, which is supposed to be bounded and Lipschitz. The chapter is mainly focused on the case of N = 3. Further, without loss of generality, the chapter supposes that Γ‎ is connected (for otherwise, one could work separately at each connected component). Such a set O is referred to as ‘regular’ in what follows. Let n denote the outward unit normal vector to Γ‎. In addition, let Oₑ := Rᶰ∖Ō: By N₀ we denote the set N ∪ {0}.

Le problème de Neumann pour certaines équations du type de Monge-Ampère sur une variété riemannienne

2000 ◽  
Vol 52 (4) ◽  
pp. 757-788
Author(s):  
Abdellah Hanani
Keyword(s):  
Elliptic Partial Differential Equation ◽  
Positive Function ◽  
Neumann Condition ◽  
Normal Vector ◽  
Unit Normal Vector ◽  
Normal Vector Field ◽  
Nonlinear Elliptic ◽  
Unit Normal Vector Field ◽  
Monge Ampere ◽  
Strictly Positive Function

AbstractLet (Mn, g) be a strictly convex riemannian manifold with C∞ boundary. We prove the existence of classical solution for the nonlinear elliptic partial differential equation of Monge-Ampère: det in M with a Neumann condition on the boundary of the form , where is an everywhere strictly positive function satisfying some assumptions, ν stands for the unit normal vector field and is a non-decreasing function in u.

scholarly journals Constant angle spacelike surface in de Sitter space S₁³

2017 ◽  
Vol 35 (3) ◽  
pp. 79-93
Author(s):  
Tugba Mert ◽  
Baki Karlıga
Keyword(s):  
Vector Field ◽  
De Sitter Space ◽  
Normal Vector ◽  
Spacelike Surface ◽  
De Sitter ◽  
Unit Normal Vector ◽  
Normal Vector Field ◽  
Constant Angle ◽  
Unit Normal Vector Field ◽  
Unit Normal

In this paper; using the angle between unit normal vector field of surfaces and a fixed spacelike axis in R₁⁴, we develop two class of spacelike surface which are called constant timelike angle surfaces with timelike and spacelike axis in de Sitter space S₁³.

scholarly journals Extension of the unit normal vector field from a hypersurface

2015 ◽  
Vol 22 (3) ◽  
Author(s):  
Roland Duduchava ◽  
Eugene Shargorodsky ◽  
George Tephnadze
Keyword(s):  
Vector Field ◽  
Existence And Uniqueness ◽  
Elementary Proof ◽  
Gradient Field ◽  
Normal Vector ◽  
Unit Normal Vector ◽  
Normal Vector Field ◽  
Unit Normal Vector Field ◽  
Outer Unit ◽  
Unit Normal

AbstractIn many applications it is important to be able to extend the (outer) unit normal vector field from a hypersurface to its neighborhood in such a way that the result is a unit gradient field. The aim of this paper is to provide an elementary proof of the existence and uniqueness of such an extension.

The Hodograph and the Balancer of any Frequency Term of the Shaking Force of Spatial Mechanisms

1996 ◽  
Vol 210 (2) ◽  
pp. 135-141 ◽  
Author(s):  
S-T Chiou ◽  
J-C Tzou
Keyword(s):  
Fourier Coefficients ◽  
Normal Vector ◽  
Unit Normal Vector ◽  
Cycle Frequency ◽  
Spatial Mechanisms ◽  
Hodograph Plane ◽  
Frequency Term ◽  
Unit Normal

It is proved in this paper that the hodograph of a frequency term (for example the kth frequency term) of the shaking force of spatial mechanisms is an ellipse. Furthermore, expressions are provided for the lengths and attitudes of the semi-axes of this ellipse in terms of Fourier coefficients of the shaking force. Accordingly, a pair of counterweights, contra-rotating at k times of cycle frequency with their axes parallel to the unit normal vector of the hodograph plane, can be installed for eliminating the frequency term of the shaking force of spatial mechanisms. An example of a seven-link 7-R spatial linkage is included.

Gradient Estimates for Spacelike Mean Curvature Flow with Boundary Conditions

2018 ◽  
Vol 62 (2) ◽  
pp. 459-469
Author(s):  
Ben Lambert
Keyword(s):  
Boundary Condition ◽  
Boundary Conditions ◽  
Mean Curvature ◽  
Neumann Boundary Condition ◽  
Mean Curvature Flow ◽  
Neumann Boundary ◽  
Curvature Flow ◽  
Gradient Estimate ◽  
Gradient Estimates ◽  
The Mean

AbstractWe prove a gradient estimate for graphical spacelike mean curvature flow with a general Neumann boundary condition in dimension n = 2. This then implies that the mean curvature flow exists for all time and converges to a translating solution.

Calculation of the unit normal vector for wall shear stress in the lattice Boltzmann model

2020 ◽  
Vol 199 ◽  
pp. 104422
Author(s):  
Li Min ◽  
Huang Jingcong ◽  
Zhang Yang ◽  
Wang Yuan ◽  
Wu Changsong ◽  
...  
Keyword(s):  
Shear Stress ◽  
Wall Shear Stress ◽  
Lattice Boltzmann ◽  
Lattice Boltzmann Model ◽  
Normal Vector ◽  
Unit Normal Vector ◽  
Wall Shear ◽  
Boltzmann Model ◽  
Unit Normal
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