scholarly journals Symmetry Problems for PDE

Symmetry ◽  
2021 ◽  
Vol 13 (12) ◽  
pp. 2240
Author(s):  
Alexander G. Ramm
Keyword(s):  
Harmonic Analysis ◽  
New Method ◽  
General Interest ◽  
Pompeiu Problem ◽  
Symmetry Problem

The results of this paper allow one to derive several results of general interest: to prove the Schiffer’s conjecture, to solve the Pompeiu problem, to prove two symmetry results in harmonic analysis and to give a new method for solving an old symmetry problem.

scholarly journals A New Method for Power Signal Harmonic Analysis

2005 ◽  
Vol 20 (2) ◽  
pp. 1235-1239 ◽  
Author(s):  
J.-Z. Yang ◽  
C.-S. Yu ◽  
C.-W. Liu
Keyword(s):  
Harmonic Analysis ◽  
New Method

Harmonic Analysis Based on Modified Hyperbolic S-Transform

2015 ◽  
Vol 733 ◽  
pp. 906-909
Author(s):  
Lin Lin ◽  
Jia Jin Qi ◽  
Xiao Huan Wu ◽  
Hong Xin Ci ◽  
Shang Qun Yang
Keyword(s):  
Harmonic Analysis ◽  
Harmonic Component ◽  
New Method ◽  
New Approach ◽  
High Noise ◽  
Noise Environment ◽  
Harmonic Control ◽  
S Transform ◽  
Simulation Results

Harmonic analysis is the foundation of harmonic control and compensation. The voltage signals with harmonic component is difficult to analysis under noise environment. This paper proposed a new approach for harmonic analysis based on Hyperbolic S-transform. Firstly, the affection for harmonic analysis by different characters of the hyperbolic window including forward-taper parameter and backward-taper parameter is compared. Secondly, the modified Hyperbolic S-transform with optimal characters is used for harmonic analysis. Finally, the analysis result of the new approach is compared with other methods. Simulation results show the effectiveness and advantages of the new method. It is very satisfied for harmonic analysis under high noise environments.

A New Method for Dynamic Analysis of Pelton Runners Using CFD/FEM Interaction

2009 ◽  
Author(s):  
Massimiliano Sanvito ◽  
Luisa Coscarelli ◽  
Emanuel Pesatori ◽  
Giorgio Turozzi ◽  
Paolo Pennacchi
Keyword(s):  
Dynamic Response ◽  
Harmonic Analysis ◽  
Dynamic Behavior ◽  
High Frequency ◽  
Pressure Profile ◽  
Point Of View ◽  
New Method ◽  
Normal Operation ◽  
Impulse Load ◽  
Structural Point

The description of the dynamic behavior of a Pelton runner during normal operation is getting more and more of interest in the design of such kind of turbines. In fact, the aim to increase the performance imposes runner designs that can become critical from a structural point of view. Each bucket is subjected to a certain number of impulses per revolution corresponding to the number of nozzles. This high frequency load could lead to a great dynamic response of the runner if some kind of resonance takes place. For these reasons, a complex harmonic analysis is to be performed during the runner project, in order to avoid any crack arising during operation. This paper describes a new method to obtain the dynamic response due to the impulse load. A Pelton runner was modeled and simulated by using a FEM code (ANSYS) and a CFD (CFX) code in order to obtain its complete dynamic behavior. By using the CFD code the complete pressure profile was derived at any point of the bucket and at any time. Whilst by using the FEM code a complex harmonic analysis was computed. Combining the information of these two simulations the behavior of the stress versus time can be derived, theoretically at any point of the runner. The results of these analysis were compared with some experimental data giving a pretty good matching.

scholarly journals Symmetry problem 1

2018 ◽  
Vol 15 ◽  
pp. 8093-8097 ◽  
Author(s):  
Alexander G. Ramm
Keyword(s):  
Boundary Data ◽  
New Method ◽  
Symmetry Problem

A symmetry problem is solved. A new method is used. The idea of this methodis to reduce to a contradiction the PDE and the over-determined boundary data on the boundary.The new method allows one to solve other symmetry problems.

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