1,025 research outputs found
A functional for the momentum equations of incompressible viscous flow
Vectorial mechanics and analytical mechanics are two time-honored forms of
classical mechanics. Vectorial mechanics is mainly based on Newton’s l aws i n a c lear a nd
simple mathematical form. It has achieved a high degree of sophistication and success in solid
mechanics. Analytical mechanics is based on the principle of virtual work and D'Alembert’s
principle, which is highly universal. Often, the term vectorial mechanics is applied to the form
based on Newton's work, to contrast it with analytical mechanics which uses two scalar
properties of motion, the kinetic and potential energies, instead of vector forces, to analyze the
motions. Analytical mechanics was primarily developed to extend the scope of classical
mechanics in a systematic, generalized and efficient way to solve problems using the concept
of constraints on systems and path integrals. In this paper, we give a functional of fluid in
Lagrangian form. Then we demonstrate that the momentum equations of incompressible
viscous flow can be achieved after several mathematical operations. At last, we show the
Eulerian approximation of the energy functional under some assumptions. Our work lays a
good foundation for our numerical methods
Chiral topological excitonic insulator in semiconductor quantum wells
We present a scheme to realize the chiral topological excitonic insulator in
semiconductor heterostructures which can be experimentally fabricated with a
coupled quantum well adjacent to twoferromagnetic insulating films. The
different mean-field chiral topological orders, which are due to the change in
the directions of the magnetization of the ferromagnetic films, can be
characterized by the TKNN numbers in the bulk system as well as by the winding
numbers of the gapless states in the edged system. Furthermore, we propose an
experimental scheme to detect the emergence of the chiral gapless edge state
and distinguish different chiral topological orders by measuring the thermal
conductance.Comment: 14 pages, 4 figure
Quantum Hall Effects in a Non-Abelian Honeycomb Lattice
We study the tunable quantum Hall effects in a non-Abelian honeycomb optical
lattice which is a many-Dirac-points system. We find that the quantum Hall
effects present different features as change as relative strengths of several
perturbations. Namely, a gauge-field-dressed next-nearest-neighbor hopping can
induce the quantum spin Hall effect and a Zeeman field can induce a so-called
quantum anomalous valley Hall effect which includes two copies of quantum Hall
states with opposite Chern numbers and counter-propagating edge states. Our
study extends the borders of the field of quantum Hall effects in honeycomb
optical lattice when the internal valley degrees of freedom enlarge.Comment: 7 pages, 6 figure
THE INFLUENCE OF THE COORDINATED DEVELOPMENT MECHANISM OF DIGITAL CULTURE INDUSTRY AND TOURISM ON RELIEVING TOURISTS’ PSYCHOLOGICAL ANXIETY
THE INFLUENCE OF THE COORDINATED DEVELOPMENT MECHANISM OF DIGITAL CULTURE INDUSTRY AND TOURISM ON RELIEVING TOURISTS’ PSYCHOLOGICAL ANXIETY
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