The Neumann Problem for Special Lagrangian Equations with Critical Phase

In this paper,we consider the Neumann problem for special Lagrangian equations with critical phase.The global gradient and Hessian estimates are obtained.Using the method of continuity,we prove the existence of solutions to this problem.

Phase Evolution Study and Optimization of the Heat Treatment Process for High Current Capacity Bi-2223 Tapes

Powder in tube process（PIT） was adopted for the fabrication of single filament Bi-2223 tapes, and a heat treatment process including the first heat treatment（HT1）, intermediate rolling（IR）, and second heat treatment（HT2） was performed. The phase evolution mechanism and microstructure changes during these heat treatment processes were systematically discussed. The influences of HT1 parameters on the phase evolution process of Bi-2223 tapes were discussed. With the optimized HT1 process, a proper Bi-2223 content of about 90% was achieved. HT2 process was also optimized by adding a post annealing process. An obvious increase of current capacity was obtained due to the enhancement of intergrain connections. Single filament Bi-2223 tapes with the critical current of Ic-90 A were fabricated with the optimized sintering process.

Universal critical properties of the Eulerian bond-cubic model

We investigate the Eulerian bond-cubic model on the square lattice by means of Monte Carlo simulations, using an efficient cluster algorithm and a finite-size scaling analysis. The critical points and four critical exponents of the model are determined for several values of n. Two of the exponents are fractal dimensions, which are obtained numerically for the first time. Our results are consistent with the Coulomb gas predictions for the critical O（n） branch for n 〈 2 and the results obtained by previous transfer matrix calculations. For n = 2, we find that the thermal exponent, the magnetic exponent and the fractal dimension of the largest critical Eulerian bond component are different from those of the critical 0（2） loop model. These results confirm that the cubic anisotropy is marginal at n = 2 but irrelevant for n〈2.

Critical parameters near the ferromagnetic-paramagnetic phase transition in La_(0.67–x)Y_xBa_(0.23)Ca_(0.1)MnO_3 compounds(x=0.10 and x=0.15)

The critical properties of the mixed manganite La0.67–x Y x Ba0.23Ca0.1Mn O3 with x=0.10 and x=0.15 around the paramagnetic（PM）-ferromagnetic（FM） phase transition were investigated through various techniques. These involved modified Arrott plots, Kouvel-Fisher method and Widom scaling relation. Magnetic data, analyzed in the critical region, using the above methods, yielded the critical exponents for（x=0.10） La0.57Y0.10Ba0.23Ca0.1Mn O3（β=0.312±0.002 and γ=1.147±0.003 at T C=299.23±0.05 K）. Moreover, the estimated critical exponents of（x=0.15） La0.52Y0.15Ba0.23Ca0.1Mn O3 were β=0.286±0.004 and γ=0.943±0.002 at T C=289.53±0.06 K. The critical exponents＇ values were close to the theoretical values of 3D-Ising model and tricritical mean-field model. These results suggested that the present composition should be close to a tricritical point in the La0.67–x Y x Ba0.23Ca0.1Mn O3 phase diagram. Expressing the field dependence as ΔS M∝H n allowed us to establish a relationship between the exponent n and the critical exponents of the material and to propose a phenomenological universal curve for the field dependence of ΔS M.

Observation of lateral long range order in superconducting FeTe thin films

We find that the superconductivity in the thin films of the formerly believed non-superconducting parent compound FeTe is accompanied by an emergence of second order with a correlation length of 742 nm and 258 nm at 10 K and 300 K, respectively. The structural phase transition found in iron pnictide superconductors, in non-superconducting FeTe bulk samples, and in FeSe superconducting thin films is not observed in the superconducting FeTe thin films. The interplay between superconductivity and long range order may suggest the crucial role of competition between electronic localization and itinerancy which leads to strong quantum fluctuations in the FeTe system.

A MODEL FOR THE VARIATIONS OF THE CRITICAL FREQUENCY OF F_2 LAYER DURING THE NEGATIVE PHASES OF IONOSPHERIC STORMS

A model for the negative phase of ionospheric storms in middle latitudes is presented. It is assumed that there will be molecule enriched air in the thermosphere above the auroral oval during the period of the main phase of a magnetic storm. The molecule enriched air is carried to the middle latitudes by thermospheric neutral wind, and at the same time it diffuses away. When the molecule enriched air arrives at the F2 layer above a station, the electron loss rate in the F2 layer increases, the electron density decreases and then the negative phase at the station begins. We have calculated the variations of the fo F2 following magnetic storms for Manzhouli （29.5°N, 117.5°E）, Freiburg （48°N, 07°E） and Billerica （43°N, 71°W） respectively. The results agree very well with typical events observed at the three stations and can be used to explain some average features of negative phase ionospheric storms in middle latitudes.

Locating the QCD critical end point through peaked baryon number susceptibilities along the freeze-out line

We investigate the baryon number susceptibilities up to fourth order along different freeze-out lines in a holographic QCD model with a critical end point（CEP）, and we propose that the peaked baryon number susceptibilities along the freeze-out line can be used as a clean signature to locate the CEP in the QCD phase diagram.On the temperature and baryon chemical potential plane, the cumulant ratio of the baryon number susceptibilities（up to fourth order） forms a ridge along the phase boundary, and develops a sword-shaped ＂mountain＂ standing upright around the CEP in a narrow and oblate region. The measurement of baryon number susceptibilities from heavy-ion collision experiments is along the freeze-out line. If the freeze-out line crosses the foot of the CEP mountain, then one can observe the peaked baryon number susceptibilities along the freeze-out line, and the kurtosis of the baryon number distributions has the highest magnitude. The data from the first phase of the beam energy scan program at the Relativistic Heavy Ion Collider indicates that there should be a peak of the kurtosis of the baryon number distribution at a collision energy of around 5 Ge V, which suggests that the freeze-out line crosses the foot of the CEP mountain and the summit of the CEP should be located nearby, around a collision energy of 3–7 GeV.

Self-organization Mechanism during the Bedform Process

This paper investigates the functional and morphological self organization phenomena that occur during the bedform process in river systems. The fluvial process has architecturally functional self organization actions that serve to self adjust the river regime. The bedform (or sand waves) process is part of the functional self organization at the middle level of the geometrical scale. By increasing the resistance of the mobile bed and simultaneously decreasing the capacity carrying sediment, the bedform serves to self adjust the river system. The morphological self organization of the bedform process is the basis for the functional self organization. The concept of the water sand interaction region is suggested, and a nonlinear model is constructed to describe the complex interaction among water flow, bed load transport, and local bed deformation, i e , the sand waves. A numerical simulation was developed based upon this model. The primary results show that the model is able to repeat many important phenomena in the bedform process, especially the critical phase transition.

Dynamical mass generation in QED_3 beyond the instantaneous approximation

In this paper, we investigate dynamical mass generation in（2＋1）-dimensional quantum electrodynamics at finite temperature. Many studies are carried out within the instantaneous-exchange approximation, which ignores all but the zero-frequency component of the boson propagator and fermion self-energy function. We extend these studies by taking the retardation effects into consideration. In this paper, we get the explicit frequency n and momentum p dependence of the fermion self-energy function and identify the critical temperature for different fermion flavors in the chiral limit. Also, the phase diagram for spontaneous symmetry breaking in the theory is presented in Tc-Nf space. The results show that the chiral condensate is just one-tenth of the scale of previous results, and the chiral symmetry is restored at a smaller critical temperature.

The Damage Spreading Method in Monte Carlo Simulations:A Brief Overview and Applications to Confined Magnetic Materials

The Damage Spreading(DS)method allows the investigation of the effect caused by tiny perturbations,in the initial conditions of physical systems,on their final stationary or equilibrium states.The damage(D(t))is determined during the dynamic evolution of a physical system and measures the time dependence of the difference between a reference(unperturbed)configuration and an initially perturbed one.In this paper we first give a brief overview of Monte Carlo simulation results obtained by applying the DS method.Different model systems under study often exhibit a transition between a state where the damage becomes healed(the frozen phase)and a regime where the damage spreads arriving at a finite(stationary)value(the damaged phase),when a control parameter is finely tuned.These kinds of transitions are actually true irreversible phase transitions themselves,and the issue of their universality class is also discussed.Subsequently,the attention is focused on the propagation of damage in magnetic systems placed in confined geometries.The influence of interfaces between magnetic domains of different orientation on the spreading of the perturbation is also discussed,showing that the presence of interfaces enhances the propagation of the damage.Furthermore,the critical transition between propagation and nonpropagation of the damage is discussed.In all cases,the determined critical exponents suggest that the DS transition does not belong to the universality class of Directed Percolation,unlike many other systems exhibiting irreversible phase transitions.This result reflects the dramatic influence of interfaces on the propagation of perturbations in magnetic systems.