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Wyszukujesz frazę "Maxwell equations" wg kryterium: Temat


Wyświetlanie 1-5 z 5
Tytuł:
Maxwell-Lorentz Matrix
Autorzy:
Montiel-Pérez, J. Yaljá
Pendleton, J.
López-Bonilla, J.
Vidal-Beltrán, S.
Powiązania:
https://bibliotekanauki.pl/articles/1177983.pdf
Data publikacji:
2018
Wydawca:
Przedsiębiorstwo Wydawnictw Naukowych Darwin / Scientific Publishing House DARWIN
Tematy:
Lorentz Group
Lorentz transformations
Maxwell equations
Opis:
Lorentz invariance of Maxwell electromagnetic equations is demonstrated in two complementary ways: first, we give a pedestrian review with three-vector equations, and we then express Maxwell equations in a four-vector matrix form (the Maxwell-Lorentz matrix) which demonstrates the intimate connection of Maxwell equations with the Lorentz group. Each Maxwell-Lorentz matrix component is the product of three matrices: a derivative matrix, a 4x4 Lorentz group generator matrix, and an electromagnetic field matrix. We obtain rotary Lorentz transformations of the electromagnetic field matrix from Lorentz equation matrices. We then transform the derivative and electromagnetic matrices and obtain an explicit matrix demonstration of Lorentz invariance of Maxwell equations. To obtain this result, we express all transformation matrices in exponential form to facilitate the application of simple Lorentz group algebra. The pedestrian approach illustrates what the Lorentz group matrix approach actually accomplishes and helps one to gain some appreciation of group theory methods.
Źródło:
World Scientific News; 2018, 96; 59-82
2392-2192
Pojawia się w:
World Scientific News
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Spinor representation of the electromagnetic field
Autorzy:
Tuladhar, B. Man
López-Bonilla, J.
Powiązania:
https://bibliotekanauki.pl/articles/1178035.pdf
Data publikacji:
2018
Wydawca:
Przedsiębiorstwo Wydawnictw Naukowych Darwin / Scientific Publishing House DARWIN
Tematy:
Faraday’s tensor
Lorentz transformations
Maxwell equations
Maxwell spinor
Newman-Penrose formalism
Quaternions
Opis:
We exhibit the tensor, spinor and Newman-Penrose (NP) forms of Faraday tensor and the Maxwell equations. Our approach is based in real and null tetrads, which allows introduce in natural manner the NP and 2-spinor techniques to study arbitrary electromagnetic fields, with special emphasis in the relationship between quaternions and Lorentz transformations.
Źródło:
World Scientific News; 2018, 95; 1-20
2392-2192
Pojawia się w:
World Scientific News
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
To the non-electromagnetic theory of light
Autorzy:
Etkin, V. A.
Powiązania:
https://bibliotekanauki.pl/articles/1179246.pdf
Data publikacji:
2017
Wydawca:
Przedsiębiorstwo Wydawnictw Naukowych Darwin / Scientific Publishing House DARWIN
Tematy:
Maxwell's equations
electromagnetic waves
light
non-electromagnetic effects
radiant energy
rethinking
Opis:
It is shown that the thermodynamic form of the equations describing processes in current-carrying systems is more general than Maxwell's equations. The erroneousness of his concept of a single electromagnetic field has been revealed. On the basis of the thermodynamic derivation of the Maxwell equations proposed earlier in their field form, a critical analysis of the postulates laid down in the basis of its electromagnetic theory of light is given, and its internal and external inconsistency is revealed. Numerous experimental data are presented, which indicate the existence of non-electromagnetic radiation. The conclusion is made that the theory of Maxwell is essentially limited and that it is necessary to develop a more general concept of light based on the existence of non-baryonic matter with properties identical to the ether and free from the contradictions of the electromagnetic theory.
Źródło:
World Scientific News; 2017, 80; 143-157
2392-2192
Pojawia się w:
World Scientific News
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Overview of adaptive and low-rank approximation algorithms for modeling influence of electromagnetic waves generated by cellphone antenna on human head
Autorzy:
Głut, Barbara
Paszyński, Maciej
Powiązania:
https://bibliotekanauki.pl/articles/2097964.pdf
Data publikacji:
2021
Wydawca:
Akademia Górniczo-Hutnicza im. Stanisława Staszica w Krakowie. Wydawnictwo AGH
Tematy:
mesh generation
mesh adaptation
Pennes bioheat equations
time-harmonic Maxwell equations
sparse factorization
low rank approximation
Opis:
This paper presents an overview of formulations and algorithms that are dedicated to modeling the influence of electromagnetic waves on the human head. We start from h adaptive approximation of a three-dimensional MRI scan of the human head. Next, we solve the time-harmonic Maxwell equations with a 1.8 GHz cellphone antenna. We compute the specific absorption rate used as the heat source for the Pennes bioheat equation modeling the heat generated by EM waves inside the head. We propose an adaptive algorithm mixed with time-stepping iterations where we simultaneously refine the computational mesh, solve the Maxwell and Pennes equations, and iterate the time steps. We employ the sparse Gaussian elimination algorithm with the low-rank compres-sion of the off-diagonal matrix blocks for the factorization of the matrices. We conclude with the statement that 15 minutes of talking with a 1.8 GHz antenna with one watt of power results in increased brain tissue temperatures (up to 38.4◦C).
Źródło:
Computer Science; 2021, 22 (4); 433--461
1508-2806
2300-7036
Pojawia się w:
Computer Science
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Some applications of Noether’s theorem
Autorzy:
Montiel-Pérez, J. Yaljá
López-Bonilla, J.
López-Vázquez, R.
Vidal-Beltrán, S.
Powiązania:
https://bibliotekanauki.pl/articles/1166045.pdf
Data publikacji:
2018
Wydawca:
Przedsiębiorstwo Wydawnictw Naukowych Darwin / Scientific Publishing House DARWIN
Tematy:
Complex Riemann-Silberstein vector
Duality rotations
Ignorable variable
Invariance of the action
Lanczos variational method
Linear differential equation of second order
Maxwell equations
Noether’s theorem
Variation of parameters
Variational symmetry
Opis:
If the action S= ∫_(t_1)^(t_2)▒〖L(q,〗 (q,) ̇t) dt is invariant under the infinitesimal transformation t ̃=t+ε τ(q,t), q ̃_r= q_r+ε ξ_r (q,t),r=1,… ,n, with ε=constant ≪1, then the Noether’s theorem permits to construct the corresponding conserved quantity. The Lanczos approach employs to ε= q_(n+1) as a new degree of freedom, thus the Euler-Lagrange equation for this new variable gives the Noether’s constant of motion. Torres del Castillo and Rubalcava-García showed that each variational symmetry implies the existence of an ignorable coordinate; here we apply the Lanczos approach to the Noether’s theorem to motivate the principal relations of these authors. The Maxwell equations without sources are invariant under duality rotations, then we show that this invariance implies, via the Noether’s theorem, the continuity equation for the electromagnetic energy. Besides, we demonstrate that if we know one solution of p(x)y''+q(x)y'+r(x)y=0, then this Lanczos technique allows obtain the other solution of this homogeneous linear differential equation.
Źródło:
World Scientific News; 2018, 106; 69-80
2392-2192
Pojawia się w:
World Scientific News
Dostawca treści:
Biblioteka Nauki
Artykuł
    Wyświetlanie 1-5 z 5

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