Itinerant Topological Magnons in SU (2) Symmetric Topological Hubbard Models with Nearly Flat Electronic Bands

We show that a suitable combination of flat-band ferromagnetism,geometry and nontrivial electronic band topology can give rise to itinerant topological magnons.An SU(2) symmetric topological Hubbard model with nearly flat electronic bands,on a Kagome lattice,is considered as the prototype.This model exhibits ferromagnetic order when the lowest electronic band is half-filled.Using the numerical exact diagonalization method with a projection onto this nearly flat band,we can obtain the magnonic spectra.In the flat-band limit,the spectra exhibit distinct dispersions with Dirac points,similar to those of free electrons with isotropic hoppings,or a local spin magnet with pure ferromagnetic Heisenberg exchanges on the same geometry.Significantly,the non-flatness of the electronic band may induce a topological gap at the Dirac points,leading to a magnonic band with a nonzero Chern number.More intriguingly,this magnonic Chern number changes its sign when the topological index of the electronic band is reversed,suggesting that the nontrivial topology of the magnonic band is related to its underlying electronic band.Our work suggests interesting directions for the further exploration of,and searches for,itinerant topological magnons.

Simulation on Residual Stress of Shot Peening Based on a Symmetrical Cell Model

The symmetrical cell model is widely used to study the residual stress induced by shot peening. However, the correlation between the predicted residual stresses and the shot peening coverage, which is a big challenge for the researchers of the symmetrical cell model, is still not established. Based on the dynamic stresses and the residual stresses outputted from the symmetrical cell model, the residual stresses corresponding to full coverage are evalu- ated by normal distribution analysis. The predicted nodal dynamic stresses with respect to four corner points indicate that the equi-biaxial stress state exists only for the first shot impact. Along with the increase of shot number, the interactions of multiple shot impacts make the fluctuation of the nodal dynamic stresses about an almost identical value more and more obvious. The mean values and standard deviations of the residual stresses gradually tend to be stable with the increase of the number of shot peening series. The mean values at each corner point are almost the same after the third peening series, which means that an equi-biaxial stress state corresponding to the full coverage of shot peening is achieved. Therefore, the mean values of the nodal residual stresses with respect to a specific transverse cross-section below the peened surface can be used to correlate the measured data by X-ray. The predicted residual stress profile agrees with the experimental results very well under 200% peening coverage. An effective correlation method is proposed for the nodal residual stresses predicted by the symmetrical cell model and the shot peening coverage.

ADAPTIVE CONTROLLER AND ITS APPLICATION IN FORCE SYSTEM OF ASYMMETRIC CYLINDER CONTROLLED BY SYMMETRIC VALVE

Partial pressure, system vibration and asymmetric system dynamic performance exit in asymmetric cylinder controller by symmetric valve hydraulic system. To solve this problem in the force control system, model reference adaptive controller is designed using equilibrium point stability theory and output error equation polynomial. The reference model is selected in such a way that it meets the system dynamic performance. Hardware configuration of asymmetric cylinder controlled by asymmetric valve hydraulic system is replaced by intelligent control algorithm, thus the cost is lowered and easy to application. Simulation results demonstrate that the proposed adaptive control sheme has good adaptive ability and well solves asymmetric dynamic performance problem. The designed adaptive controller is fairly robust to load disturbance and system parameter variation.

Anisotropic Plane Symmetric Two-Fluid Cosmological Model with Time-Varying G and A

We investigate a two-fluid anisotropic plane symmetric cosmological model with variable gravitational constant G（t） and cosmological term A（t）. In the two-fluid model, one fluid is chosen to be that of the radiation field modeling the cosmic microwave background and the other one a perfect fluid modeling the material content of the universe. Exact solutions of the field equations are obtained by using a special form for the average scale factor which corresponds to a specific time-varying deceleration parameter. The model obtained presents a cosmological scenario which describes an early acceleration and late-time deceleration. The gravitation constant increases with the cosmic time whereas the cosmological term decreases and asymptotically tends to zero. The physical and kinematical behaviors of the associated fluid parameters are discussed.

A New Symmetric Model for Predicting Ternary Thermodynamic Properties from its Three Binary Systems

A new symmetric model for predicting ternary thermodynamic properties from its three binary systems has been presented. The application of this new model to the prediction of the ternary mixing enthalpy of Ga-Bi-Sn system and the ternary excess Gibbs energy of AgCl-LiCl-KCl system shows that the calculated results are close to the experimental data.

Small-signal modeling of GaN HEMT switch with a new intrinsic elements extraction method

A novel and accurate method is proposed to extract the intrinsic elements of the GaN high-electron-mobility transistor（HEMT） switch.The new extraction method is verified by comparing the simulated S-parameters with the measured data over the 5-40 GHz frequency range.The percentage errors E（ij） within 3.83% show the great agreement between the simulated S-parameters and the measured data.

CALCULATION OF NaCl-BaCl_2-SrCl_2 PHASE DIAGRAM

The mathematical formulas are given for calculating the partial molar thermodynamic proper- ties in a ternary system from its three corresponding binary systems based on the new ternary symmetric model presented by the authors in the foregoing paper.Applying this model to NaCl-BaCl_2-SrCl_2 system,the phase diagram of which as well as some isothermal sections have been calculated.The devations of temperature between the calculated and experimen- tal diagrams are less than five degrees.

On Nondifferentiable Higher-Order Symmetric Duality in Multiobjective Programming Involving Cones

In this paper,we point out some deficiencies in a recent paper(Lee and Kim in J.Nonlinear Convex Anal.13:599–614,2012),and we establish strong duality and converse duality theorems for two types of nondifferentiable higher-order symmetric duals multiobjective programming involving cones.

Discriminating the HTM and MLRSM models in collider studies via doubly charged Higgs boson pair production and the subsequent leptonic decays

We present a case study for the doubly charged Higgs boson H^(±±)pair production ine^(+)+e^(-)and pp colliders with their subsequent decays to four charged leptons.We consider the Higgs Triplet Model(HTM),which is not restricted by the custodial symmetry,and the Minimal Left-Right Symmetric Model(MLRSM).These models include scalar triplets with different complexities of scalar potentials and,because of experimental restrictions,completely different scales of non-standard triplet vacuum expectation values.In both models,a doubly charged Higgs bosonH^(±±)can acquire a mass of hundreds of gigaelectronvolts,which can be probed at the HL-LHC,futuree^(+)+e^(-),and hadron colliders.We take into account a comprehensive set of constraints on the parameters of both models coming from neutrino oscillations,LHC,e^(+)+e^(-),and low-energy lepton flavor violating data and assume the same mass ofH^(±±).Our finding is that theH^(±±)pair production in lepton and hadron colliders is comparable in both models,though more pronounced in the MLRSM.We show that the decay branching ratios can be different within both models,leading to distinguishable four-lepton signals,and that the strongest are 4μevents yielded by theMLRSM.Typically,we find that the MLRSM signals are one order of magnitude larger those in theHTM.For example,the pp→to 4μMLRSM signal for 1 TeVH^(±±)mass results in a clearly detectable significance of S■11for the HL-LHC and S≥290 for the FCC-hh.Finally,we provide quantitative predictions for the dilepton invariant mass distributions and lepton separations,which help to identify non-standard signals.