1,487 research outputs found

    Thermodynamic modeling of phase composition for Fe-Ca-Si-Al system

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    In this paper, theoretical studies on the construction of phase structure diagrams of the Fe-Ca-Si-Al system as modeling composition of alloy by Thermodynamic-diagram analysis (TDA) were carried out. TDA analysis allows predicting the optimal composition of alloys using phase structure diagrams of the multicomponent systems. TDA excludes complex mathematical apparatus. Also, TDA allows to obtaine data for the Fe-Ca-Si-Al system, a diagram of phase relationships, each elementary subsystem of which is independent. By analyzing the binary systems, the state diagram of Fe-Ca-Si-Al metal system was constructed, which simulates the final phase composition of the ferroalloy. The reliability of the effectiveness of these methods is confirmed by large-scale laboratory melting tests

    Thermodynamic modeling of phase composition for Fe-Ca-Si-Al system

    Get PDF
    In this paper, theoretical studies on the construction of phase structure diagrams of the Fe-Ca-Si-Al system as modeling composition of alloy by Thermodynamic-diagram analysis (TDA) were carried out. TDA analysis allows predicting the optimal composition of alloys using phase structure diagrams of the multicomponent systems. TDA excludes complex mathematical apparatus. Also, TDA allows to obtaine data for the Fe-Ca-Si-Al system, a diagram of phase relationships, each elementary subsystem of which is independent. By analyzing the binary systems, the state diagram of Fe-Ca-Si-Al metal system was constructed, which simulates the final phase composition of the ferroalloy. The reliability of the effectiveness of these methods is confirmed by large-scale laboratory melting tests

    Weyl group, CP and the kink-like field configurations in the effective SU(3) gauge theory

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    Effective Lagrangian for pure Yang-Mills gauge fields invariant under the standard space-time and local gauge SU(3) transformations is considered. It is demonstrated that a set of twelve degenerated minima exists as soon as a nonzero gluon condensate is postulated. The minima are connected to each other by the parity transformations and Weyl group transformations associated with the color su(3) algebra. The presence of degenerated discrete minima in the effective potential leads to the solutions of the effective Euclidean equations of motion in the form of the kink-like gauge field configurations interpolating between different minima. Spectrum of charged scalar field in the kink background is discussed.Comment: 10 pages, 1 figure, added references for sections 1 and

    Yang-Mills Fields Quantization in the Factor Space

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    The perturbation theory over inverse interaction constant 1/g1/g is constructed for Yang-Mills theory. It is shown that the new perturbation theory is free from the gauge ghosts and Gribov's ambiguities, each order over 1/g1/g presents the gauge-invariant quantity. It is remarkable that offered perturbation theory did not contain divergences, at least in the vector fields sector, and no renormalization procedure is necessary for it.Comment: 27 pages, Latex, no figure

    Soliton solutions in an effective action for SU(2) Yang-Mills theory: including effects of higher-derivative term

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    The Skyrme-Faddeev-Niemi (SFN) model which is an O(3) σ\sigma model in three dimensional space upto fourth-order in the first derivative is regarded as a low-energy effective theory of SU(2) Yang-Mills theory. One can show from the Wilsonian renormalization group argument that the effective action of Yang-Mills theory recovers the SFN in the infrared region. However, the thoery contains an additional fourth-order term which destabilizes the soliton solution. In this paper, we derive the second derivative term perturbatively and show that the SFN model with the second derivative term possesses soliton solutions.Comment: 7 pages, 3 figure

    Lagrangian and Hamiltonian Formalism on a Quantum Plane

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    We examine the problem of defining Lagrangian and Hamiltonian mechanics for a particle moving on a quantum plane Qq,pQ_{q,p}. For Lagrangian mechanics, we first define a tangent quantum plane TQq,pTQ_{q,p} spanned by noncommuting particle coordinates and velocities. Using techniques similar to those of Wess and Zumino, we construct two different differential calculi on TQq,pTQ_{q,p}. These two differential calculi can in principle give rise to two different particle dynamics, starting from a single Lagrangian. For Hamiltonian mechanics, we define a phase space TQq,pT^*Q_{q,p} spanned by noncommuting particle coordinates and momenta. The commutation relations for the momenta can be determined only after knowing their functional dependence on coordinates and velocities. Thus these commutation relations, as well as the differential calculus on TQq,pT^*Q_{q,p}, depend on the initial choice of Lagrangian. We obtain the deformed Hamilton's equations of motion and the deformed Poisson brackets, and their definitions also depend on our initial choice of Lagrangian. We illustrate these ideas for two sample Lagrangians. The first system we examine corresponds to that of a nonrelativistic particle in a scalar potential. The other Lagrangian we consider is first order in time derivative

    Tunneling mechanism of light transmission through metallic films

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    A mechanism of light transmission through metallic films is proposed, assisted by tunnelling between resonating buried dielectric inclusions. This is illustrated by arrays of Si spheres embedded in Ag. Strong transmission peaks are observed near the Mie resonances of the spheres. The interaction among various planes of spheres and interference effects between these resonances and the surface plasmons of Ag lead to mixing and splitting of the resonances. Transmission is proved to be limited only by absorption. For small spheres, the effective dielectric constant can be tuned to values close to unity and a method is proposed to turn the resulting materials invisible.Comment: 4 papges, 5 figure

    Noncommutativity In The Mechanics Of A Free Massless Relativistic Particle

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    We show the existence of a noncommutative spacetime structure in the context of a complete discussion on the underlying spacetime symmetries for the physical system of a free massless relativistic particle. The above spacetime symmetry transformations are discussed for the first-order Lagrangian of the system where the transformations on the coordinates, velocities and momenta play very important roles. We discuss the dynamics of this system in a systematic manner by exploiting the symplectic structures associated with the four dimensional (non-)commutative cotangent (i.e. momentum phase) space corresponding to a two dimensional (non-)commutative configuration (i.e. target) space. A simple connection of the above noncommutativity (NC) is established with the NC associated with the subject of quantum groups where SLq,q1(2)SL_{q,q^{-1}} (2) transformations play a decisive role.Comment: LaTeX file, 19 page

    Gribov Problem for Gauge Theories: a Pedagogical Introduction

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    The functional-integral quantization of non-Abelian gauge theories is affected by the Gribov problem at non-perturbative level: the requirement of preserving the supplementary conditions under gauge transformations leads to a non-linear differential equation, and the various solutions of such a non-linear equation represent different gauge configurations known as Gribov copies. Their occurrence (lack of global cross-sections from the point of view of differential geometry) is called Gribov ambiguity, and is here presented within the framework of a global approach to quantum field theory. We first give a simple (standard) example for the SU(2) group and spherically symmetric potentials, then we discuss this phenomenon in general relativity, and recent developments, including lattice calculations.Comment: 24 pages, Revtex 4. In the revised version, a statement has been amended on page 11, and References 14, 16 and 27 have been improve
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