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1

Thermo-mechanical deformation in magneto micropolar thermoelastic medium with modified Fourier and Ohm's law

Singh R., Kumar V.

International Journal of Applied Mechanics and Engineering

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2011

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Vol. 16, no 1

83-105

EN

The present investigation is concerned with a two dimensional problem in a magnetic micropolar thermoelastic half space, whose surface is subjected to thermo-mechanical sources in the presence of transverse magnetic field with modified Ohm's and Fourier's law. The Laplace and Fourier transforms are used to solve the problem. As an application, concentrated normal force and thermal source are taken to illustrate the utility of the approach. The transformed components of displacement, stress, couple stress, electric field and current density vector are derived. Some special cases of interest are also deduced from the present investigation.

2

The nonthermal interactions between electrons and metal crystalline lattice

Pike-Biegunski M. J.

Zeszyty Naukowe. Elektryka / Politechnika Łódzka

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2001

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z. 95

17--40

EN

This paper proposes new theoretical explanation, and the experimental evidence, about the longitudinal forces in wires conducting electrical currents with high densities. Traditionally, from the times of Ampere, such forces were always thought to be electrodynamics in nature. The still existing opinion prevailed, that these longitudinal forces help to understand the nature of current/wire interactions: from wire stretching to explosion. Some researchers proposed what they called "Newtonian Electrodynamics", a peculiar new form of electromagnetism with rules differing from those of classical, Maxwellian electrodynamics. Such forces would be, accordingly to this concept, created under the high current density conditions. We abandoned this concept since it is not needed to explain the nature of the longitudinal forces in wires. We also developed a new concept, based not in electromagnetism, but in quantum mechanics instead. Accordingly to this new concept, there are two components, which pertain to the transport of energy from electrons to metal crystalline lattice: their kinetic energy and momentum. From a general perspective, kinetic energy is known to be transformed into a Joule's heat. On the other hand, the electrons' momentum allows for creating forces acting on the lattice. These two components must exist always, but they become visible under high current densities in conjunction. This in turn creates a new picture about the common laws of the electrical current. Such a novel approach is based on quantum mechanics, but also shows, that the electrical current phenomena must be always treated with the understanding of the atomic metal structure, known under the "crystalline - metallic" name. Once Joule and Ohm's old concept of the "uniform electrically conducting body" is applied, there remains no place for quantum mechanics. Without quantum mechanics, physics of electricity becomes the unreal science of the past, and the understanding of the electrical current phenomena in metals becomes artificial. The new findings presented here create a modified concept in the science of electricity, which requires a reexamination of some old rules, such as the laws of Ohm and Joule.

PL

W niniejszej pracy poddano weryfikacji prawa Ohma i Joulea. W oparciu o zebrany materiał fenomenologiczny, bazując na zasadach zachowania pędu i energii elektronów w przewodniku metalicznym wykazano ograniczoność owych praw w ich istniejącej postaci. Wnioski oparto o rozważania kwantowo-mechaniczne, podbudowane wynikami doświadczeń. W szczególności wykazano, iż przekaz pędu elektronów do sieci krystalicznej metalu prowadzi do powstawania siły podłużnej w przewodniku, wiodącej do wystąpienia deformacji sprężystych lub niesprężystych jako funkcji gęstości prądu elektrycznego. Takie deformacje pochłaniając znaczną energię źródła prądu wiodą do powstawania pracy sił elektrotensometrycznych. Omawiane efekty są małe bądź zgoła niezauważalne w typowych utylitarnych zastosowaniach metali w elektrotechnice czy elektronice, kiedy to gęstość prądu nie przekracza wartości 5 x 103Acm-2. W przypadkach jednak prądów o dużej gęstości generowana jest fala dźwiękowa podłużna, przewodnik ulega rozciąganiu, zerwaniu jedno-punktowemu lub segmentacji, wreszcie może on nawet eksplodować. Prawa Joulea i Ohma w ogóle nie uwzględniają tych zjawisk, mimo iż Ampere i de la Rive już w roku 1822 opublikowali wyniki eksperymentów, w których demonstrowano istnienie oddziaływań podłużnych prądu z przewodnikiem. Takie nowe rozumienie oddziaływania prądu z metalem nie tylko w formie wydzielanego ciepła, ale także generowanych sił podłużnych modyfikuje fundamentalne zasady, na których opiera się fizyka prądu elektrycznego. Badania efektów wielkoprądowych będą zdaniem autora miały ogromny wpływ na dalszy rozwój nauki o prądzie elektrycznym oraz na postać elektrotechniki i elektroniki w 21 wieku.

3

Nauka o elektryczności w Polsce w XIX wieku i w początkach XX wieku w dwusetną rocznicę zbudowania baterii elektrycznej przez Alessandro Voltę

Średniawa B.

Kwartalnik Historii Nauki i Techniki

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2001

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R. 46, nr 1

41--56

EN

The year 1999 saw the bicentenary anniversary of the construction of the electrical battery by Alessandro Volta. This invention led to the development if the science of electricity. We shall present the influence of the early discoveries in the domain of electricity on teaching and research in this domain in Poland in the 19th century and in the first years of 20th century. In the 19th century four Polish universities were active. These were the universities in Cracow and Lwów, in the Austrian held part of Poland, and the Vilna University, in the part occupied by Russia. In Warsaw, which was under Russian occupation, a Polish university was established in 1816. It was active until 1831, when it was closed; it was then reactivated in 1862 and closed once again in 1869. All these universities had collections of physical instruments from the early years of the 19th century, among them also electrical instruments. In the 1830s, the professors of Cracow and Warsaw universities began to do research in electricity, and several papers on electricity and physical chemistry were published. The first Polish university handbooks on electricity appeared in 1786 and in 1827. At the end of the 19th century and in the first two decades of the 20th century, also handbooks and monographs on the theory of electricity and electrotechnics were published.