On sets of uniqueness for harmonic functions in the unit circle

1997 ◽  
Vol 87 (5) ◽  
pp. 3828-3858
Author(s):  
Yu. Ya. Vymenets
Keyword(s):  
Unit Circle ◽  
Harmonic Functions ◽  
Sets Of Uniqueness

scholarly journals Sets of uniqueness for functions regular in the unit circle

1952 ◽  
Vol 87 (0) ◽  
pp. 325-345 ◽  
Author(s):  
Lennart Carleson
Keyword(s):  
Unit Circle ◽  
Sets Of Uniqueness

A theorem on positive harmonic functions

1949 ◽  
Vol 45 (2) ◽  
pp. 207-212 ◽  
Author(s):  
S. Verblunsky
Keyword(s):  
Harmonic Function ◽  
Unit Circle ◽  
Harmonic Functions ◽  
Closed Interval ◽  
Positive Harmonic Function ◽  
Image Position ◽  
Function Conjugate ◽  
Positive Harmonic Functions

1. Let z = reiθ, and let h(z) denote a (regular) positive harmonic function in the unit circle r < 1. Then h(r) (1−r) and h(r)/(1 − r) tend to limits as r → 1. The first limit is finite; the second may be infinite. Such properties of h can be obtained in a straightforward way by using the fact that we can writewhere α(phgr) is non-decreasing in the closed interval (− π, π). Another method is to writewhere h* is a harmonic function conjugate to h. Then the functionhas the property | f | < 1 in the unit circle. Such functions have been studied by Julia, Wolff, Carathéodory and others.

Mean values and classes of harmonic functions

1984 ◽  
Vol 96 (3) ◽  
pp. 501-505 ◽  
Author(s):  
Thomas Ramsey ◽  
Yitzhak Weit
Keyword(s):  
Unit Circle ◽  
Harmonic Functions ◽  
Borel Measure ◽  
Mean Value ◽  
Finite Complex ◽  
Mean Values ◽  
Complex Borel Measure ◽  
Generalized Mean ◽  
Image Position

Let μ be a finite complex Borel measure supported on the unit circle.In this paper, we are concerned with the characterization of the sets of functions satisfying the generalized mean value equation of the form.and for all ξ ∈ , | ξ | = R for some fixed R > 0.

scholarly journals Spline Parameterization of Complex Planar Domains for Isogeometric Analysis

2017 ◽  
Vol 47 (1) ◽  
pp. 18-35 ◽  
Author(s):  
Sangamesh Gondegaon ◽  
Hari K. Voruganti
Keyword(s):  
Unit Circle ◽  
Isogeometric Analysis ◽  
Harmonic Functions ◽  
Geometric Model ◽  
Mean Value ◽  
Mapping Method ◽  
Control Points ◽  
Computationally Efficient ◽  
B Spline ◽  
Domain Mapping

Abstract Isogeometric Analysis (IGA) involves unification of modelling and analysis by adopting the same basis functions (splines), for both. Hence, spline based parametric model is the starting step for IGA. Representing a complex domain, using parametric geometric model is a challenging task. Parameterization problem can be defined as, finding an optimal set of control points of a B-spline model for exact domain modelling. Also, the quality of parameterization, too has significant effect on IGA. Finding the B-spline control points for any given domain, which gives accurate results is still an open issue. In this paper, a new planar B-spline parameterization technique, based on domain mapping method is proposed. First step of the methodology is to map an input (non-convex) domain onto a unit circle (convex) with the use of harmonic functions. The unique properties of harmonic functions: global minima and mean value property, ensures the mapping is bi-jective and with no self-intersections. Next step is to map the unit circle to unit square to make it apt for B-spline modelling. Square domain is re-parameterized by using conventional centripetal method. Once the domain is properly parameterized, the required control points are computed by solving the B-spline tensor product equation. The proposed methodology is validated by applying the developed B-spline model for a static structural analysis of a plate, using isogeometric analysis. Different domains are modelled to show effectiveness of the given technique. It is observed that the proposed method is versatile and computationally efficient.

Inequalities for the derivatives of a bounded harmonic function

1948 ◽  
Vol 44 (2) ◽  
pp. 155-158 ◽  
Author(s):  
S. Verblunsky
Keyword(s):  
Harmonic Function ◽  
Unit Circle ◽  
Harmonic Functions ◽  
Conformal Transformations ◽  
Alternative Method ◽  
Schwarz’S Lemma ◽  
The One ◽  
Image Position ◽  
Derivatives Of ◽  
Bounded Harmonic Function

If h(r, θ) is harmonic in the unit circle | r | < 1 and satisfies the condition | h | ≤ 1, then there is a function u(ø) which satisfies | u | ≤ 1 such thatand conversely. Hence, any properties of such harmonic functions should be deducible from equation (1). A number of such properties have been proved by Koebe (Math. Z. 6 (1920), 52–84, 69), using Schwarz's lemma and the geometry of simple conformal transformations. They can be deduced from (1) together with an elementary lemma on the rearrangement of a function (Lemma 1 below). As, however, students of this subject will regard Koebe's method as the one best adapted to establish his theorems, we shall illustrate the alternative method by considering two new problems, namely to find max ∂h/∂r, max ∂h/∂θ, where the maximum in each case is taken for all harmonic functions h which satisfy

Stable geometric properties of analytic and harmonic functions

2013 ◽  
Vol 155 (2) ◽  
pp. 343-359 ◽  
Author(s):  
RODRIGO HERNÁNDEZ ◽  
MARÍA J. MARTÍN
Keyword(s):  
Unit Circle ◽  
Unit Disk ◽  
Harmonic Functions ◽  
Harmonic Mapping ◽  
Geometric Properties ◽  
Geometric Conditions

AbstractGiven any sense preserving harmonic mapping f=h+ḡ in the unit disk, we prove that for all |λ|=1 the functions fλ=h+λḡ are univalent (resp. close-to-convex, starlike, or convex) if and only if the analytic functions Fλ=h+λg are univalent (resp. close-to-convex, starlike, or convex) for all such λ. We also obtain certain necessary geometric conditions on h in order that the functions fλ belong to the families mentioned above. In particular, we see that if fλ are univalent for all λ on the unit circle, then h is univalent.

Proof of Poisson's Formula

1961 ◽  
Vol 57 (1) ◽  
pp. 186-186 ◽  
Author(s):  
Bengt Åkerberg
Keyword(s):  
Unit Circle ◽  
Harmonic Functions ◽  
Image Position

Let f(z)=u(x, y)+iv(x, y) be regular in a domain containing the unit circle C. If where r < 1, then is regular in |z| ≤ 1 and we have and taking real parts and imaginary parts we obtain Poisson's formulae for the harmonic functions u and v.

On the Radial Symmetry Property for Harmonic Functions

2020 ◽  
Vol 64 (10) ◽  
pp. 9-19
Author(s):  
V. V. Volchkov ◽  
Vit. V. Volchkov
Keyword(s):  
Harmonic Functions ◽  
Symmetry Property ◽  
Radial Symmetry
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