Antisymmetric quadrupole mode of coherent structures in wall-bounded turbulence

Abstract Experiments were conducted in a water tunnel by tomographic time-resolved particle image velocimetry （Tomo-TRPIV）. The Reynolds number Reo is 2 460 on the base of momentum thickness. According to the physical mechanism of the stretch and compression of multi-scale vortex structures in the wall-bounded turbulence, the topological characteristics of turbulence statistics in logarithmic layer were illustrated by local-averaged velocity structure function. During coherent structures bursting, results reveal that the topological structures of velocity gradients, velocity strain rates and vorticities behave as antisymmetric quadrupole modes. A three-layer antisymmetric quadrupole vortex packet confirms that there is a tight relationship between the outer layer and the near-wall layer.

AN EXACT SYMPLECTIC SOLUTION FOR THE DYNAMIC ANALYSIS OF SHEAR DEFORMABLE ANTISYMMETRIC ANGLE-PLY LAMINATED PLATES

From the mixed variational principle, by the selection of the state variables and its dual variables, the Hamiltonian canonical equation for the dynamic analysis of shear deformable antisymmetric angle-ply laminated plates is derived, leading to the mathematical frame of symplectic geometry and algorithms, and the exact solution for the arbitrary boundary conditions is also derived by the adjoint orthonormalized symplectic expansion method. Numerical results are presented with the emphasis on the effects of length/thickness ratio, arbitrary boundary conditions, degrees of anisotropy, number of layers, ply-angles and the corrected coefficients of transverse shear.

Engineered photonic spin Hall effect of Gaussian beam in antisymmetric parity-time metamaterials

A model of the photonic spin Hall effect(PSHE)in antisymmetric parity-time(APT)metamaterials with incidence of Gaussian beams is proposed here.We derive the displacement expression of the PSHE in APT metamaterials based on the transport properties of Gaussian beams in positive and negative refractive index materials.Furthermore,detailed discussions are provided on the APT scattering matrix,eigenstate ratio,and response near exceptional points in the case of loss or gain.In contrast to the unidirectional non-reflection in parity-time(PT)symmetric systems,the transverse shift that arises from both sides of the APT structure is consistent.By effectively adjusting the parameters of APT materials,we achieve giant displacements of the transverse shift.Finally,we present a multi-layer APT structure consisting of alternating left-handed and right-handed materials.By increasing the number of layers,Bragg oscillations can be generated,leading to an increase in resonant peaks in transverse shift.This study presents a new approach to achieving giant transverse shifts in the APT structure.This lays a theoretical foundation for the fabrication of related nano-optical devices.

Antisymmetric planar Hall effect in rutile oxide films induced by the Lorentz force

The conventional Hall effect is linearly proportional to the field component or magnetization component perpendicular to a film. Despite the increasing theoretical proposals on the Hall effect to the in-plane field or magnetization in various special systems induced by the Berry curvature, such an unconventional Hall effect has only been experimentally reported in Weyl semimetals and in a heterodimensional superlattice. Here, we report an unambiguous experimental observation of the antisymmetric planar Hall effect(APHE) with respect to the in-plane magnetic field in centrosymmetric rutile RuO_(2) and IrO_(2) single-crystal films. The measured Hall resistivity is found to be linearly proportional to the component of the applied in-plane magnetic field along a particular crystal axis and to be independent of the current direction or temperature. Both the experimental observations and theoretical calculations confirm that the APHE in rutile oxide films is induced by the Lorentz force. Our findings can be generalized to ferromagnetic materials for the discovery of anomalous Hall effects and quantum anomalous Hall effects induced by in-plane magnetization. In addition to significantly expanding knowledge of the Hall effect, this work opens the door to explore new members in the Hall effect family.

PHYSICAL PROPERTIES OF THE SYMMETRIC AND ANTISYMMETRIC MOTIONS AND RELATED ENERGY CONVERSION

The physical properties of the symmetric and antisymmetric motions,such as the conservation of the ab- solute angular momentum,the mutual conversions between various forms of energy,have been analysed by using the sets of equaticns in p-coordinates controlling the motions in the primitive equation model atmosphere.The results show that only the symmetric component of zoral geopotential difference caused by orography and that of the zonal frictional torque,have contribution to the change of the global angular momentum,and that the mutual conversions between various forms of energy,in addition to those similar to the results in the classical case, irclude those associated with the symmetric and antisymmetric motions.

Symmetric and antisymmetric vector solitons for the fractional quadric-cubic coupled nonlinear Schrodinger equation

The fractional quadric-cubic coupled nonlinear Schrodinger equation is concerned,and vector symmetric and antisymmetric soliton solutions are obtained by the square operator method.The relationship between the Lévy index and the amplitudes of vector symmetric and antisymmetric solitons is investigated.Two components of vector symmetric and antisymmetric solitons show a positive and negative trend with the Lévy index,respectively.The stability intervals of these solitons and the propagation constants corresponding to the maximum and minimum instability growth rates are studied.Results indicate that vector symmetric solitons are more stable and have better interference resistance than vector antisymmetric solitons.

A Modified Symmetric and Antisymmetric Decomposition-Based Three-Dimensional Numerical Manifold Method for Finite Elastic-Plastic Deformations

There are relatively few studies on large rotation or deformation by means of the three-dimensional(3D)numerical manifold method(NMM).A new modified symmetric and antisymmetric decomposition(MSAD)theory is developed and implemented into the 3D NMM,eliminating the false-volume expansion and false-rotation strain/stress problems.The Jaumann rate is used to measure the material rotation,and the geometric stiffness built on the Jaumann rate is deduced.The incremental formulas of the MSAD-based 3D NMM and a practical guide on the implementation of the MSAD theory are given in detail and exemplified.The new theory and formulas can be applied to analyze both large rotation and large deformation problems.Based on the hypoelasto-plasticity theory and the unified strength theory,the unified yield criterion with associated flow rule is implemented into the MSAD-based 3D NMM.Several typical examples are studied,showing the advantage and potential of the new MSAD theory and the MSAD-based 3D NMM.

Emergent antisymmetric wrinkling patterns in films on ridged substrates

We report the formation of antisymmetric wrinkling patterns in films on ridged substrates induced by the buckling instability of the substrates via finite element simulations and experiments.Our simulated results reveal that the uniaxial compression along the ridge can trigger both the wrinkling instability of the film and the lateral buckling instability of the ridge.The latter could change the wrinkles from a symmetric pattern to an antisymmetric pattern in a range of film-substrate modulus ratio and aspect ratio of the ridge profile,as validated by the experimental observations.A three-dimensional phase diagram with four buckling patterns,i.e.,sole ridge buckling pattern,antisymmetric wrinkling pattern with different wavelengths from ridge buckling,symmetric wrinkling pattern without ridge buckling,and antisymmetric wrinkling pattern with the same wavelength as ridge buckling,is built with respect to the uniaxial compression,modulus ratio,and aspect ratio.The results not only elucidate how and when the interplay between the wrinkling instability and the ridge instability results in the formation of the antisymmetric wrinkling pattern but also offer a way to generate controllable complex wrinkling patterns.

Planar-symmetry-breaking induced antisymmetric magnetoresistance in van der Waals ferromagnet Fe_(3)GeTe_(2)

Recently discovered magnetic van der Waals(vdW)materials provide an ideal platform to explore low-dimensional magnetism and spin transport.Its vdW interaction nature opens up unprecedented opportunities to build vertically stacked heterostructures with novel properties and functionalities.By engineering the planar structure as an alternative degree of freedom,herein we demonstrate an antisymmetric magnetoresistance(MR)in a vdW Fe_(3)GeTe_(2)flake with a step terrace that breaks the planar symmetry.This antisymmetric MR originates from a sign change of the anomalous Hall effect and the continuity of the current transport near the boundary of magnetic domains at the step edge.A repeatable domain wall due to the unsynchronized magnetization switching is responsible for this sign change.Such interpretation is supported by the observation of field-dependent domain switching,and the step thickness,temperature,and magnetic field orientation dependent MR.This work opens up new opportunities to encode magnetic information by controlling the planar domain structures in vdW magnets.

Influence of vibration on spatiotemporal structure of the pattern in dielectric barrier discharge

The influence of vibration on the spatiotemporal structure of the pattern in dielectric barrier discharge is studied for the first time.The spatiotemporal structure of the pattern investigated by an intensified charge-coupled device shows that it is an interleaving of three sublattices, whose discharge sequence is small rods–halos–large spots in each half-cycle of the applied voltage.The result of the photomultiplier indicates that the small rods are composed of moving filaments.The moving mode of the moving filaments is determined to be antisymmetric stretching vibration by analyzing a series of consecutive images taken by a high-speed video camera.The antisymmetric stretching vibration affects the distribution of wall charges and leads to the halos.Furthermore, large spots are discharged only at the centers of the squares consisting of vibrating filaments.The vibration mechanism of the vibrating filaments is dependent on the electric field of wall charges.

Frequency Dependence of Resonance Field of One-Dimensional Heisenberg Antiferromagnet KCuF3

The frequency dependence of the in-plane angular change of the antiferromagnetic resonance （AFMR） field of KCuF3 is systematically measured at frequencies ranging from 3.8 to 10.6 GHz at 4.2K. The effect of inequivalent g-tensors is found to gradually diminish with decreasing the frequency, and completely vanish when the frequency is decreased to the lower-frequency branch of C-band, while the effect of the effective anisotropy field is significantly enhanced with decreasing the frequency. The calculated AFMR field Hres based on the eight-sublattice model proposed by Yamada and Kato [J. Phys. Soc. Jpn. 63 （1994）289] is in good agreement with the experimental data.

Different Kinds of Discrete Breathers in Three Types of One-Dimensional Models

The dynamics of different kinds of discrete breathers in three types of one-dimensionai monatomic chains with on-site and inter-site potentiais are investigated. The existence and evolution of symmetric breather, antisymmetric breather, and multibreather in one-dimensionai models are proved by using rotating wave approximation, local anharmonic approximation, and the numerical method. The linear stability of these breathers is investigated by using Lyapunov stable anaiysis. The localization and stability of breathers in three types of models correlate closely to the system nonlinear parameter β.

NEW POINTS OF VIEW ON THE NONLOCAL FIELD THEORY AND THEIR APPLICATIONS TO THE FRACTURE MECHANICS(Ⅱ)——RE-DISCUSS NONLINEAR CONSTITUTIVE EQUATIONS OF NONLOCAL THERMOELASTIC BODIES

In this paper, nonlinear constitutive equations are deduced strictly according to the constitutive axioms of rational continuum mechanics. The existing judgments are modified and improved. The results show that the constitutive responses of nonlocal thermoelastic body are related to the curvature and higher order gradient of its material space, and there exists an antisymmetric stress whose average value in the domain occupied by thermoelastic body is equal to zero. The expressions of the antisymmetric stress and the nonlocal residuals are given. The conclusion that the directions of thermal conduction and temperature gradient are consistent is reached. In addition, the objectivity about the nonlocal residuals and the energy conservation law of nonlocal field is discussed briefly, and a formula for calculating the nonlocal residuals of energy changing with rigid motion of the spatial frame of reference is derived.

NEW POINTSOF VIEW ON THE NONLOCAL FIELD THEORY AND THEIR APPLICATIONS TO THE FRACTURE MECHANICS( Ⅲ) ——RE_DISCUSS THE LINEAR THEORY OF NONLOCAL ELASTICITY

In this paper, it is proven that the balance equation of energy is the first integral of the balance equation of momentum in the linear theory of nonlocal elasticity. In other words, the balance equation of energy is not an independent one. It is also proven that the residual of nonlocal body force identically equals zero. This makes the transform formula of the nonlocal residual of energy much simpler. The linear nonlocal constitutive equations of elastic bodies are deduced in details, and a new formula to calculate the antisymmetric stress is given.

Multimodal fiber antenna for proximity and stress sensing

Fiber sensors are commonly used to detect environmental,physiological,optical,chemical,and biological factors.Thermally drawn fibers offer numerous advantages over other commercial products,including enhanced sensitivity,accuracy,improved functionality,and ease of manufacturing.Multimaterial,multifunctional fibers encapsulate essential internal structures within a microscale fiber,unlike macroscale sensors requiring separate electronic components.The compact size of fiber sensors enables seamless integration into existing systems,providing the desired functionality.We present a multimodal fiber antenna monitoring,in real time,both the local deformation of the fiber and environmental changes caused by foreign objects in proximity to the fiber.Time domain reflectometry propagates an electromagnetic wave through the fiber,allowing precise determination of spatial changes along the fiber with exceptional resolution and sensitivity.Local changes in impedance reflect fiber deformation,whereas proximity is detected through alterations in the evanescent field surrounding the fiber.The fiber antenna operates as a waveguide to detect local deformation through the antisymmetric mode and environmental changes through the symmetric mode.This multifunctionality broadens its application areas from biomedical engineering to cyber-physical interfacing.In antisymmetric mode,the device can sense local changes in pressure,and,potentially,temperature,pH,and other physiological conditions.In symmetric mode,it can be used in touch screens,environmental detection for security,cyber-physical interfacing,and human-robot interactions.

Symmetric Mach reflection configuration with asymmetric unsteady solution

Symmetric Mach reflection in steady supersonic flow has been usually studied by solving a half-plane problem with the symmetric line treated as reflecting surface,thus losing the opportunity to discover antisymmetric flow structures.Here in this paper we treat this problem as an entire-plane problem.Using an unsteady numerical approach,we find that the two sliplines exhibit antisymmetric unsteadiness if the Mach stem height is small while the flow remains symmetric if the Mach stem height is large.The mechanism by which disturbance,generated in the downstream of the flow duct between the two sliplines,propagates upstream is identified and it is also shown that the interaction between the transmitted expansion waves and the sliplines increases the amplitude of the unstable modes.The present study suggests a new type of compressible jet that deserves further studies.

Analysis of antisym metric cross-ply laminates using high-order shear deformation theories:a meshless approach

For many years finite element method(FEM)was the chosen numerical method for the analysis of composite structures.However,in the last 20 years,the scientific community has witnessed the birth and development of several meshless methods,which are more flexible and equally accurate numerical methods.The meshless method used in this work is the natural neighbour radial point interpolation method(NNRPIM).In order to discretize the problem domain,the NNRPIM only requires an unstructured nodal distribution.Then,using the Voronoi mathematical concept,it enforces the nodal connectivity and constructs the background integration mesh.The NNRPIM shape functions are constructed using the radial point interpolation technique.In this work,the displacement field of composite laminated plates is defined by high-order shear deformation theories.In the end,several antisymmetric cross-ply laminates were analysed and the NNRPIM solutions were compared with the literature.The obtained results show the efficiency and accuracy of the NNRPIM formulation.

Symmetry energy and experimentally observed cold fragments in intermediate heavy-ion collisions

An attempt is made to study the symmetry energy at the time of primary fragment formation from the experimentally observed cold fragments for a neutron-rich system of ^64Ni ＋ ^9Be at 140 MeV/nucleon,utilizing the recent finding that the excitation energy becomes lower for more neutron-rich isotopes with a given Z value.The extracted α（sym）/T values from the cold fragments,based on the Modified Fisher Model（MFM）,are compared to those from the primary fragments of the antisymmetrized molecular dynamics（AMD） simulation and become consistent with the simulation when the I = N —Z value becomes larger,indicating that the excitation energy of these neutron-rich isotopes is indeed lower.