scholarly journals MODELING OF DYNAMIC PROCESSES BY THE METHOD OF HYBRID INTEGRAL TRANSFORM OF BESSEL-EULER-BESSEL TYPE ON THE POLAR AXIS

Author(s):  
S.G . BLAZHEVSKIY ◽  
О.М. LENYUK ◽  
O.M. NIKITINA ◽  
M.I. SHYNKARYK
2020 ◽  
Vol 8 (2) ◽  
pp. 40-55
Author(s):  
A. Gromyk ◽  
I. Konet ◽  
T. Pylypyuk

The unique exact analytical solutions of parabolic boundary value problems of mathematical physics in piecewise homogeneous wedge-shaped solid cylinder were constructed at first time by the method of integral and hybrid integral transforms in combination with the method of main solutions (matrices of influence and Green matrices). The cases of assigning on the verge of the wedge the boundary conditions of Dirichlet and Neumann and their possible combinations (Dirichlet – Neumann, Neumann – Dirichlet) are considered. Finite integral Fourier transform by an angular variable $\varphi \in (0; \varphi_0)$, a Fourier integral transform on the Cartesian segment $(-l_1;l_2)$ by an applicative variable $z$ and a hybrid integral transform of the Hankel type of the first kind on a segment $(0;R)$ of the polar axis with $n$ points of conjugation by an radial variable $r$ were used to construct solutions of investigated initial-boundary value problems. The consistent application of integral transforms by geometric variables allows us to reduce the three-dimensional initial boundary-value problems of conjugation to the Cauchy problem for a regular linear inhomogeneous 1st order differential equation whose unique solution is written in a closed form. The application of inverse integral transforms restores explicitly the solution of the considered problems through their integral image. The structure of the solution of the problem in the case of setting the Neumann boundary conditions on the wedge edges is analyzed. Exact analytical formulas for the components of the main solutions are written and the theorem on the existence of a single bounded classical solution of the problem is formulated. The obtained solutions are algorithmic in nature and can be used (using numerical methods) in solving applied problems.


2019 ◽  
Vol 76 (2) ◽  
pp. 60-87 ◽  
Author(s):  
Renato M. Cotta ◽  
Kleber M. Lisboa ◽  
Marcos F. Curi ◽  
Stavroula Balabani ◽  
João N. N. Quaresma ◽  
...  

Author(s):  
H.H. Rotermund

Chemical reactions at a surface will in most cases show a measurable influence on the work function of the clean surface. This change of the work function δφ can be used to image the local distributions of the investigated reaction,.if one of the reacting partners is adsorbed at the surface in form of islands of sufficient size (Δ>0.2μm). These can than be visualized via a photoemission electron microscope (PEEM). Changes of φ as low as 2 meV give already a change in the total intensity of a PEEM picture. To achieve reasonable contrast for an image several 10 meV of δφ are needed. Dynamic processes as surface diffusion of CO or O on single crystal surfaces as well as reaction / diffusion fronts have been observed in real time and space.


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