A Quasi—One—Dimensional Model for a Solar Flux Tube

We develop the quasi-one-dimensional flux tube model with magnetohydrodynamical equations.In order to know whether the magnetic field can maintain their similar structure from photosphere to chromosphere,we suppose that the flux tube is thin in radius relative to the length,and that the quantities in the cross section are averaged.The radii of the flux tube and the magnetic field are numerically simulated.One of the important results shows that the flux tube does not expand as quickly as the existing model when it is out of the photoxphere with high velocity.This is consistent with observations of the magnetic field in the photosphere and chromosphere.     

Mesoscopic Persistent Currents,Aharonov—Bohm Magnetic Flux and Time Reversal Symmetry

We discuss the effect of Aharonov-Bohm magnetic flux on the time reversal symmetric properties of mesoscopic metallic ring systems.It is usually believed that AB flux causes time reversal symmetry breaking.We analyse the case of mesoscopic persistent currents and find out that AB flux does not break time reversal symmetry.our arguments are supported by the general theory of mesoscopic persistent currents.     

EXPERIMENTAL EVIDENCE OF THE SELF-SIMILARITY AND LONG-RANGE CORRELATIONS OF THE EDGE FLUCTUATIONS IN HT-6M TOKAMAK

To better understand long-time-scale transport dynamics, the rescaled range analysis techniques, the autocorrelation function (ACF) and the probability distribution function (PDF) are used to investigate long-range dependences in edge plasma fluctuations in HT-6M tokamak. The results reveal the self-similar characters of the electrostatic fluctuations with self-similarity parameters (Hurst exponent) ranging from 0.64 to 0.79, taking into consideration the {\vec E}_r×{\vec B} rotation-sheared effect. Fluctuation ACFs of both the ion saturation current and the floating potential, as well as PDF of the turbulence-induced particle flux, have two distinct time scales. One corresponds to the decorrelation time scale of local fluctuations (μs) and the other lasts to the order of the confinement time (ms). All these experimental results suggest that some of the mechanisms of the underlying turbulence are consistent with plasma transport as characterized by self-organized criticality(SOC).     

The space environment monitor aboard FY-2 satellite

The space environment monitor (SEM) aboard FY-2 satellite consists of the high energy particle detector (HEPD) and the solar X-ray flux detector (SXFD). The SEM can provide real-time monitoring of flare and solar proton event for its operation at geostationary orbit and is also the first Chinese space system for monitoring and alerting solar proton event. During the 23rd solar maximum cycle, almost all the solar proton events that took place in this period are monitored and some of them are predicted successfully by analyzing the characteristics of X-ray flare monitored by the SEM. Some basic variation characteristics of particle at geostationary orbit are found such as day-night periodic variation of particle flux, the electron flux with energy >1.4 MeV in the scope from 10 to 200/cm2 s sr and the proton flux with energy >1.1 MeV in the scope from 600 to 8000/cm·s·sr during the time with no magnetic storm and solar eruption.     

Aerothermal characteristics of bleed slot in hypersonic flows

Two types of flow configurations with bleed in two-dimensional hypersonic flows are numerically examined to investigate their aerodynamic thermal loads and related flow structures at choked conditions. One is a turbulent boundary layer flow without shock impingement where the effects of the slot angle are discussed, and the other is shock wave boundary layer interactions where the effects of slot angle and slot location relative to shock impingement point are surveyed. A key separation is induced by bleed barrier shock on the upstream slot wall, resulting in a localized maximum heat flux at the reattachment point. For slanted slots, the dominating flow patterns are not much affected by the change in slot angle, but vary dramatically with slot location relative to the shock impingement point. Different flow structures are found in the case of normal slot, such as a flow pattern similar to typical Laval nozzle flow, the largest separation bubble which is almost independent of the shock position. Its larger detached distance results in 20% lower stagnation heat flux on the downstream slot corner, but with much wider area suffering from severe thermal loads. In spite of the complexity of the flow patterns, it is clearly revealed that the heat flux generally rises with the slot location moving downstream, and an increase in slot angle from 20° to 40° reduces 50% the heat flux peak at the reattachment point in the slot passage. The results further indicate that the bleed does not raise the heat flux around the slot for all cases except for the area around the downstream slot corner. Among all bleed configurations, the slot angle of 40° located slightly upstream of the incident shock is regarded as the best.     

SIMULATION ON LOCAL FLUX CREEP IN TYPE-Ⅱ SUPERCONDUCTORS

Using C programming language, we have simulated the flux creep process in nonideal type-Ⅱ superconductors. Global and local magnetization curves are calculated and the logarithmic time dependence of local magnetic induction B under a constant external field is examined. The effects of nonuniform pinning potential and self-organized criticality (SOC) model on the simulations are discussed. The results show that the main feature of flux creep is the relaxation effect. The form of hysteresis loops is dependent on the magnetic field sweep rate. SOC can account for the occurrence of fluctuation to a certain extent and nonuniform pinning potential can enhance the fluctuation.     

GEKF, GUKF and GGPF based prediction of chaotic time-series with additive and multiplicative noises

On the assumption that random interruptions in the observation process are modelled by a sequence of independent Bernoulli random variables, this paper generalize the extended Kalman filtering （EKF）, the unscented Kalman filtering （UKF） and the Gaussian particle filtering （GPF） to the case in which there is a positive probability that the observation in each time consists of noise alone and does not contain the chaotic signal （These generalized novel algorithms are referred to as GEKF, GUKF and GGPF correspondingly in this paper）. Using weights and network output of neural networks to constitute state equation and observation equation for chaotic time-series prediction to obtain the linear system state transition equation with continuous update scheme in an online fashion, and the prediction results of chaotic time series represented by the predicted observation value, these proposed novel algorithms are applied to the prediction of Mackey-Glass time-series with additive and multiplicative noises. Simulation results prove that the GGPF provides a relatively better prediction performance in comparison with GEKF and GUKF.     

Conditional Analysis and Biorthogonal Decomposition of Plasma Turbulence in the CT—6B Tokamak

Coherent structures in the CT-6B tokamak plasma turbulence are detected by using conditional averaging.The results show that the coherent structures are short-lived and do not propagate in the radial direction.The biorthogonal decomposition technique is adopted to analyse further the coherent structure in the turbulence,The time evolution and spatial distribution of the coherent structures are obtained.     

Effect of Connected Multi-Ring Impurity Scattering on Quantum Transport

We investigate the quantum transmission properties of connected multi-rings with impurities and analyse the effect of the impurities on the band formation in these geometric structures. It is shown that energy bands and band gaps are formed clearly while there is not any fixed band structure for the case of the single ring. The number of resonant peaks in conductance bands increases with the number of rings. Some essential differences are pointed out and magnetic properties of loop configurations in the presence of Aharonov-Bohm flux are explored as well.     

On the detectability of Galactic dark matter annihilation into monochromatic gamma-rays

Monochromatic γ-rays are thought to be the smoking gun signal for identifying dark matter annihilation. However, the flux of monochromatic γ-rays is usually suppressed by virtual quantum effects since dark matter should be neutral and does not couple with γ-rays directly. In this work, we study the detection strategy of the monochromatic γ-rays in a future space-based detector. The flux of monochromatic γ-rays between 50 GeV and several TeV is calculated by assuming the supersymmetric neutralino as a typical dark matter candidate. The detection both by focusing on the Galactic center and in a scan mode that detects γ-rays from the whole Galactic halo are compared. The detector performance for the purpose of monochromatic γ-ray detection, with different energy and angular resolution, field of view, and background rejection efficiencies, is carefully studied with both analytical and fast Monte-Carlo methods.     

Steady-state sound field in enclosures

The classical normal-mode theory expresses the steady-state soundfield in an enclosure produced by a sound source as a series of normal modes ofvibration.Experimental facts are not often explained by this theory,and it wasconjectured that the normal-mode expression is not the complete solution ofthe wave equation in the enclosure,but only the reverberant part of it,and thereshould be an additional term representing the direct spherical radiation to makethe solution complete.The problem is examined by critically reviewing the de-rivation of the normal-mode expression,and by theoretical analysis of thesteady-state sound field in the room and experimental measurements therein.The conjecture is thus confirmed,and it is definitely shown that the sound fieldshould contain the direct wave as well as the standing waves(normal modes)formed by the confinement of the boundary surfaces.Relevant mathematicalexpressions are derived.     

Controlled decoherence of floating flux qubits

In Born-Markov approximation,this paper calculates the energy relaxation time T 1 and the decoherence time T 2 of a floating flux qubit by solving the set of Bloch-Redfield equations.It shows that there are two main factors influencing the floating flux qubits:coupling capacitor in the circuit and the environment resistor.It also discusses how to improve the quantum coherence time of a qubit.Through shunt connecting/series connecting inductive elements,an inductive environment resistor is obtained and further the reactance component of the environment resistor is improved,which is beneficial to the enhancement of decoherence time of floating flux qubits.     

Rotational symmetry of classical orbits, arbitrary quantization of angular momentum and the role of the gauge field in two-dimensional space

We study quantum–classical correspondence in terms of the coherent wave functions of a charged particle in two- dimensional central-scalar potentials as well as the gauge field of a magnetic flux in the sense that the probability clouds of wave functions are well localized on classical orbits. For both closed and open classical orbits, the non-integer angular-momentum quantization with the level space of angular momentum being greater or less than is determined uniquely by the same rotational symmetry of classical orbits and probability clouds of coherent wave functions, which is not necessarily 2π-periodic. The gauge potential of a magnetic flux impenetrable to the particle cannot change the quantization rule but is able to shift the spectrum of canonical angular momentum by a flux-dependent value, which results in a common topological phase for all wave functions in the given model. The well-known quantum mechanical anyon model becomes a special case of the arbitrary quantization, where the classical orbits are 2π-periodic.     

Domain wall dynamics in magnetic nanotubes driven by an external magnetic field

We use the Landau–Lifshitz–Gilbert equation to investigate field-driven domain wall propagation in magnetic nanotubes. We find that the distortion is maximum as the time becomes infinite and the exact rigid-body solutions are obtained analytically. We also find that the velocity increases with increasing the ratio of inner radius and outer radius. That is to say, we can accelerate domain wall motion not only by increasing the magnetic field, but also by reducing the thickness of the nanotubes.     

Time evolution of distribution functions in dissipative environments

By introducing the thermal entangled state representation,we investigate the time evolution of distribution functions in the dissipative channels by bridging the relation between the initial distribution function and the any time distribution function.We find that most of them are expressed as such integrations over the Laguerre-Gaussian function.Furthermore,as applications,we derive the time evolution of photon-counting distribution by bridging the relation between the initial distribution function and the any time photon-counting distribution,and the time evolution of Rfunction characteristic of nonclassicality depth.     

Conductance in an Aharonov-Bohm Interferometer with Parallel-Coupled Double Dots

We present a theoretical study of the conductance in an Aharonov-Bohm interferometer containing two coupled quantum dots. The interdot tunneling divides the interferometer into two coupled subrings, where opposite magnetic fluxes are threaded separately while the net flux is kept zero. Using the Green function technique we derive the expression of the linear conductance. It is found that the Aharonov-Bohm effect still exists, and when the level of each dot is aligned, the exchange of the Fano and Breit-Wigner resonances in the conductance can be achieved by tuning the magnetic flux. When the two levels are mismatched the exchange may not happen. Further, for some specific asymmetric systems where the coupling strengths between the two dots and the leads are not equal, the flux can change the Fano resonance into an antiresonance, which is absent in symmetric systems.     

Propagation properties of a modified surface plasmonic waveguide with an arc slot

We introduce a modified surface plasmonic waveguide with an arc slot. The dependences of distribution of energy flux density, effective index, propagation length and mode area of the symmetric mode supported by this waveguide on geometrical parameters and working wavelength are analysed by using the finite-difference frequency-domain (FDFD) method. Results show that the energy flux density distributes mainly in four corners which are formed by two arcs, and the closer to the corners it is, the stronger the energy flux density will be. The effective index, the propagation length and the mode area are influenced by geometrical parameters, including the width, the thickness and the arc radius of the surface plasmonic waveguide, as well as the working wavelength. It has been shown that the surface plasmonic waveguide with an arc slot has better propagation properties than the surface plasmonic waveguide with a straight slot. This work may be helpful for applying the slot surface plasmonic waveguide to integrated photonics.     

Bursty events and incremental diffusion in a local diffusion and multi—scale convection system

A one-dimensional cellular automaton is defined without the critical gradient rule (Δh>Δh_c) which is essential to the existence of avalanches in self-organized criticality (SOC) models. Instead, only the local diffusion rule is used, however, the characteristics of SOC, such as the bursty behaviour, power-law decay in fluctuation spectra, self-similarity over a broad range of scales and long-time correlations, are still observed in these numerical experiments. This numerical model is established to suggest that the bursty events and the incremental diffusion observed universally in fusion experiments do not necessarily imply the submarginal dynamics.     

Morphology and photoluminescence of BaAl12O19:Mn2+ green phosphor prepared by flux method

This paper reports that the green phosphor BaAl11.9O19:0.1Mn2+ is prepared by a flux assisted solid state reaction method.The effect of flux systems on the crystal structure,morphology and luminescent properties of the phosphor are studied in detail.The samples are characterized by the application of x-ray diffraction patterns,scanning electron microscopy patterns,luminescent spectra and decay curves.The results show that a pure phase BaAl12O19 can be achieved at the firing temperature above 1300℃ by adding the proper flux system,the firing temperature is reduced at least 200℃ in comparison with the conventional solid state reaction method.Maximum photoluminescence emission intensity is observed at 517 nm for(AlF3+Li2CO3) flux system under vacuum ultraviolet region(147 nm) excitation.The photoluminescence emission intensity and the decay time of these phosphor is found to be more superior to that of the corresponding sample prepared by the conventional solid state reaction method implying the suitability of this route for the preparation of display device worthy phosphor materials.     

Persistent fast kink magnetohydrodynamic waves detected in a quiescent prominence

Small-scale, cyclic, transverse motions of plasma threads are usually seen in solar prominences, which are often interpreted as magnetohydrodynamic(MHD) waves. Here, we observed small-scale decayless transverse oscillations in a quiescent prominence, and they appear to be omnipresent. The oscillatory periods of the emission intensity and a proxy for the line-of-sight Doppler shift are about half period of the displacement oscillations. This feature agrees well with the fast kink-mode waves in a flux tube. All the moving threads oscillate transversally spatially in phase and exhibit no significant damping throughout the visible segments, indicating that the fast kink MHD waves are persistently powered and ongoing dissipating energy is transferred to the ambient plasma in the quiet corona. However, our calculations suggest that the energy taken by the fast kink MHD waves alone can not support the coronal heating on the quiet Sun.