Interconnection and composition of Dirac structures for Lagrange-Dirac systems

2011 ◽  
Author(s):  
Henry O. Jacobs ◽  
Hiroaki Yoshimura
Keyword(s):  
Dirac Structures ◽  
Dirac Systems

Dirac structures and variational formulation of port-Dirac systems in nonequilibrium thermodynamics

2020 ◽  
Vol 37 (4) ◽  
pp. 1298-1347
Author(s):  
François Gay-Balmaz ◽  
Hiroaki Yoshimura
Keyword(s):  
Entropy Production ◽  
Variational Formulation ◽  
Nonequilibrium Thermodynamics ◽  
Open Systems ◽  
Ideal Gas ◽  
Irreversible Processes ◽  
Lagrangian Systems ◽  
Specific Class ◽  
Dirac Structures ◽  
Dirac Systems

Abstract The notion of implicit port-Lagrangian systems for nonholonomic mechanics was proposed in Yoshimura & Marsden (2006a, J. Geom. Phys., 57, 133–156; 2006b, J. Geom. Phys., 57, 209–250; 2006c, Proc. of the 17th International Symposium on Mathematical Theory of Networks and Systems, Kyoto) as a Lagrangian analogue of implicit port-Hamiltonian systems. Such port-systems have an interconnection structure with ports through which power is exchanged with the exterior and which can be modeled by Dirac structures. In this paper, we present the notions of implicit port-Lagrangian systems and port-Dirac dynamical systems in nonequilibrium thermodynamics by generalizing the Dirac formulation to the case allowing irreversible processes, both for closed and open systems. Port-Dirac systems in nonequilibrium thermodynamics can be also deduced from a variational formulation of nonequilibrium thermodynamics for closed and open systems introduced in Gay-Balmaz & Yoshimura (2017a, J. Geom. Phys., 111, 169–193; 2018a, Entropy, 163, 1–26). This is a type of Lagrange–d’Alembert principle for the specific class of nonholonomic systems with nonlinear constraints of thermodynamic type, which are associated to the entropy production equation of the system. We illustrate our theory with some examples such as a cylinder-piston with ideal gas, an electric circuit with entropy production due to a resistor and an open piston with heat and matter exchange with the exterior.

scholarly journals Plasmons in anisotropic Dirac systems

2021 ◽  
Vol 5 (2) ◽  
Author(s):  
Roland Hayn ◽  
Te Wei ◽  
Vyacheslav M. Silkin ◽  
Jeroen van den Brink
Keyword(s):  
Dirac Systems

scholarly journals Gauged sigma-models with nonclosed 3-form and twisted Jacobi structures

2020 ◽  
Vol 2020 (11) ◽  
Author(s):  
Athanasios Chatzistavrakidis ◽  
Grgur Šimunić
Keyword(s):  
Sigma Models ◽  
Sigma Model ◽  
Target Space ◽  
Two Dimensional ◽  
Courant Algebroids ◽  
Dirac Structures ◽  
Courant Algebroid ◽  
Abelian Case ◽  
Jacobi Manifolds ◽  
Jacobi Structure

Abstract We study aspects of two-dimensional nonlinear sigma models with Wess-Zumino term corresponding to a nonclosed 3-form, which may arise upon dimensional reduction in the target space. Our goal in this paper is twofold. In a first part, we investigate the conditions for consistent gauging of sigma models in the presence of a nonclosed 3-form. In the Abelian case, we find that the target of the gauged theory has the structure of a contact Courant algebroid, twisted by a 3-form and two 2-forms. Gauge invariance constrains the theory to (small) Dirac structures of the contact Courant algebroid. In the non-Abelian case, we draw a similar parallel between the gauged sigma model and certain transitive Courant algebroids and their corresponding Dirac structures. In the second part of the paper, we study two-dimensional sigma models related to Jacobi structures. The latter generalise Poisson and contact geometry in the presence of an additional vector field. We demonstrate that one can construct a sigma model whose gauge symmetry is controlled by a Jacobi structure, and moreover we twist the model by a 3-form. This construction is then the analogue of WZW-Poisson structures for Jacobi manifolds.

Electronic and magnetic properties of honeycomb transition metal monolayers: first-principles insights

2014 ◽  
Vol 16 (26) ◽  
pp. 13383-13389 ◽  
Author(s):  
Xinru Li ◽  
Ying Dai ◽  
Yandong Ma ◽  
Baibiao Huang
Keyword(s):  
Field Theory ◽  
Monte Carlo ◽  
Magnetic Properties ◽  
Transition Metal ◽  
First Principles ◽  
Mean Field Theory ◽  
Mean Field ◽  
Electronic And Magnetic Properties ◽  
Dirac Systems

The electronic and magnetic properties of d-electron-based Dirac systems are studied by combining first-principles with mean field theory and Monte Carlo approaches.

Dirac systems that contain discontinuity conditions

2016 ◽  
Author(s):  
Tuba Gulsen ◽  
Etibar S. Panakhov
Keyword(s):  
Dirac Systems ◽  
Discontinuity Conditions

scholarly journals Absence of high-energy spectral concentration for Dirac systems with divergent potentials

2005 ◽  
Vol 135 (4) ◽  
pp. 689-702 ◽  
Author(s):  
M. S. P. Eastham ◽  
K. M. Schmidt
Keyword(s):  
Spectral Density ◽  
High Energy ◽  
Regularity Conditions ◽  
Absolutely Continuous Spectrum ◽  
Absolutely Continuous ◽  
One Dimensional ◽  
Local Maxima ◽  
Dirac Systems ◽  
Additional Regularity ◽  
Spectral Concentration

It is known that one-dimensional Dirac systems with potentials q which tend to −∞ (or ∞) at infinity, such that 1/q is of bounded variation, have a purely absolutely continuous spectrum covering the whole real line. We show that, for the system on a half-line, there are no local maxima of the spectral density (points of spectral concentration) above some value of the spectral parameter if q satisfies certain additional regularity conditions. These conditions admit thrice-differentiable potentials of power or exponential growth. The eventual sign of the derivative of the spectral density depends on the boundary condition imposed at the regular end-point.

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