Integrability and Gauge Fixing for Bosonic String on AdS3 × S^3

The integrability and the TST transformation of the bosonic string on AdS3× S^3 are studied. The Lax connection for gauge fixed theory is constructed and proved to be fiat.     

AdS/QCD and Applications of Light-Front Holography

Light-front holography leads to a rigorous connection between hadronic amplitudes in a higher dimensional anti-de Sitter(AdS) space and frame-independent light-front wavefunctions of hadrons in(3 + 1)-dimensional physical space-time,thus providing a compelling physical interpretation of the AdS/CFT correspondence principle and AdS/QCD,a useful framework which describes the correspondence between theories in a modified AdS 5 background and confining field theories in physical space-time.To a first semiclassical approximation,where quantum loops and quark masses are not included,this approach leads to a single-variable light-front Schro¨dinger equation which determines the eigenspectrum and the light-front wavefunctions of hadrons for general spin and orbital angular momentum.The coordinate z in AdS space is uniquely identified with a Lorentz-invariant coordinate ζ which measures the separation of the constituents within a hadron at equal light-front time.The internal structure of hadrons is explicitly introduced and the angular momentum of the constituents plays a key role.We give an overview of the light-front holographic approach to strongly coupled QCD.In particular,we study the photon-to-meson transition form factors(TFFs) FMγ(Q 2) for γ→ M using light-front holographic methods.The results for the TFFs for the η and η ' mesons are also presented.Some novel features of QCD are discussed,including the consequences of confinement for quark and gluon condensates.A method for computing the hadronization of quark and gluon jets at the amplitude level is outlined.     

Gravitational quasi-normal modes of static R~2 Anti-de Sitter black holes

In this paper, we study the gravitational quasi-normal modes(QNMs) for a static R~2 black hole(BH) in Anti-de Sitter(AdS) spacetime. The corresponding master equation of odd parity is derived and the QNMs are evaluated by the Horowitz and Hubeny method. Meanwhile the stability of such BH is also discussed through the temporal evolution of the perturbation field. Here we mainly consider the coefficient λ, which is related to the radius of AdS black hole, on the QNMs of the R~2 AdS BH. The results show that the Re(ω) and |Im(ω)| of the QNMs increase together as |λ| increases for a given angular momentum number l. That indicates with a larger value of |λ| the corresponding R~2 AdS BH returns to stable much more quickly. The dynamic evolution of the perturbation field is consistent with the results derived by the Horowitz and Hubeny method. Since in the conformal field theory the QNMs can reflect its approach to equilibrium, so our related results could be referential to studies of the AdS/CFT conjecture. The relationship between λ and the properties of the static R~2 BH might be helpful for the development of R~2 gravitational theory.     

On the Next-leading order Heavy-Quark Potential from AdS/CFT

Applying the AdS/CFT correspondence,the expansion of the heavy-quark potential of N = 4 supersymmetric Yang-Mills theory at large N c is carried out to the next-leading term in the large ’t Hooft coupling at zero temperature.The strong coupling corresponds to the semi-classical expansion of the stringsigma model,the gravity dual of the Wilson loop operator,with the next-leading term expressed in terms of functional determinants of fluctuations.The singularities of these determinants are examined and their contributions are evaluated numerically.We find the next-leading order correction is negative and suppressed by minus square root of the ’t Hooft coupling relative to the leading order.     

P-V criticality and Joule-Thomson expansion of charged AdS black holes in the Rastall gravity

We discuss the P-V criticality and the Joule-Thomson expansion of charged AdS black holes in the Rastall gravity. We find that although the equation-of-state of a charged AdS black hole in the Rastall gravity is related to the Rastall parameter λ, its reduced equation-of-state at the critical point is independent of the Rastall parameter λ, as is the case in the Einstein gravity where λ=0. This is the reason why the critical exponents are not related to the Rastall parameter λ. We also find that the inversion temperature T_i is related to the Rastall parameter λ,but that the minimum inversion temperature T_i~(min) and the ratio ε between the minimum inversion temperature and the critical temperature are both independent of the Rastall parameter λ. At the critical point, the thermodynamic evolution of a charged AdS black hole in the Rastall gravity behaves as in the van der Waals fluid and charged AdS black hole in the Einstein gravity. We show the inversion curves and isenthalpic curves in the T-P plane and analyze the effect of the Rastall constant λ on the inversion curves of a charged AdS black hole during the Joule-Thomson expansion.     

STOCHASTIC CONVERGENCE PROPERTIES OF THE TWO-PARAMETER ADAPTIVE LATTICE FILTERS

In this paper,the perturbation theory of the matrix eigenvalues,the operator spectral norm and a fixed-point theorem are used to research on the stochastic convergence properties of the two-parameter adaptivelattice filters.The relative difference value between the two parameters is a important factor.We obtainsome results:1.The singular values of the mean of elementary operator vary in a circle which has the radiusproportionated to ,they vary not only in magnitude,but also in direction due to; 2.Theeigenvalues of the mean square of elementary operator vary in a circle,its radius is proportional to also;3.The limits of stepsize are stricker than the ones of the one-parameter lattice filters;4.Zero-misadjustment can not be obtained.The misadjustment varys in the range where the center is equal to themisadjustment of the one-parameter lattice filters and the length is propertional to 5.The relationsbetween the misadjustment and order Nare neither linear nor exponential,but are in some conditions betweenthe     

Dark Energy Density in Brane World

We present a possible explanation to the tiny positive cosmological constant under the frame of AdS5 spacetime embedded by a dS4 brahe. We calculate the dark energy density by summing the zero point energy of massive scalar fields in AdS5 spacetime. Under the assumption that the radius of AdS5 spacetime is of the same magnitude as the radius of observable universe, the dark energy density in dS4 brahe is obtained, which is smaller than the observational value. The reasons are also discussed.     

THE COMPUTATION OF PARTIAL COHERENCE FUNCTION APPLIED FOR SOUND SOURCE IDENTIFICATION

In this paper,a new method is applied to get the computation formula of partial coherence function.The main attention is paid to the computation formula of the partial coherence function with three andfour signals.The advantages of the method discussed in the paper are clear in physical meaning and easyto compute at the end of the paper,the application of the method to the identification of an aircompressor noise source is presented and the results are satisfactory.     

THE THEORY AND MEASURED RESULTS FOR THE DISPERSION OF ACOUSTIC GRAVITY WAVES IN LAYERED ATMOSPHERE

The equation of infrasonic wave taking into account the gravitational effect in moving media isderived,with multi-layer atmospheric model.The equations of frequency dispersion are specified bydivergence of velocty,using a multi-layer atmospheric model.The dispersion characteristic ofacoustic-gravity wave is evaluated.Numerical results have shown that both the phase and groupvelocities are different two,the acoustic and gravity-waves.The dispersion of the acoustic velocitiesare more sensitive to wind.Usually the short period group velocity in downwind can differ aslarge as 10% from that in upwind.In some atmospheric model,the gravity-waves velocities areagain divided to several groups,with different dispersion characteristics.The new results of infrasonicdispersion characteristics agree well with the observations from the nuclear explosion.     

(n+1)-Dimensional Gravity Duals to Quantum Criticalities with Spontaneous Symmetry Breaking

We reexamine the charged AdS domain wall solution to the Einstein–Abelian–Higgs model proposed by Gubser et al.as holographic superconductors at quantum critical points and comment on their statement about the uniqueness of gravity solutions.We generalize their explorations from(3+1)-dimensions to arbitrary n+1Ds and find that the n+1 5D charged AdS domain walls are unstable against electric perturbations.     

Metastability of Ising spin chains with nearest—neighbour and next—nearest—neighbour interactions in random fields

One-dimensional Ising systems in random fields (RFs) are studied taking into account the nearest-neighbour and next-nearest-neighbour interactions. We investigate two distributions of RFs: binary and Gaussian distributions. We consider four cases of the exchange couplings: ferro－ferromagnetic (F－F), ferro－antiferromagnetic (F－AF), antiferro－ferromagnetic (AF－F) and antiferro－antiferromagnetic (AF－AF). The energy minima of chains of no more than 30 spins with periodic boundary conditions are analysed exactly. We found that the average number of energy minima grows exponentially with the number of spins in both cases of RFs. The energy distributions across the corresponding energy minima are shown. The effects of RFs on both the average and density of metastable states are explained. For a weak RF, the energy distributions display a multipartitioned structure. We also discuss the frustration effect due to RFs and exchange fields. Finally, the distributions of magnetization are calculated. The absolute value of magnetization averaged over all metastable states decreases logarithmically with the number of spins.     

Holographic models of the scalar sector of QCD

We investigate the AdS/QCD duality for the two-point correlation functions of the lowest dimension scalar meson and scalar glueball operators,in the case of the Soft Wall holographic model of QCD.Masses and decay constants as well as gluon condensates are compared to their QCD estimates.In particular,the role of the boundary conditions for the bulk-to-boundary propagators is emphasized.     

THE 4—3—N MATRIX MULTI-CHANNEL SOUND SYSTEM

In this paper,it is proved that,although there are only three independent signals in a pano-ramic sound system,there can be different forms of each of the three channel signals to be selected.The general method of N(≥3)channel reproduction using the three independent signals and itsapplication as an example of N=8 are to be discussed.It may improve the reproduction effectof the conventional quadraphony. The use of this system in radio broadcasting and its compatibility with conventional systemare also discussed.     

A METHOD FOR NUMERICAL PREDICTION OF THE AVERAGE SOUND FIELD IN SHALLOW WATER

The theory of the smooth-average field in shallow water is presented;the smooth-average expres-sion suitable for long ranges and the image-source expression suitable for short ranges are combinedtogether to give a more complete calculating method of the average field.The correspondingcomputer programs,which make the calculation of the average field easy and rapid,have heendeveloped.Some examples of application of the method are given,and the calculated results arequite consistent with the experiments.     

Magnetic phase transition and the corresponding magnetostriction of intermetallic compounds RMnsGe2（R=Sm,Gd）

The temperature dependence of lattice constants a and c of intermetallic compounds RMn₂Ge₂ (R=Sm, Gd) is measured in the temperature range 10－800K by using the x-ray diffraction method. The magnetoelastic anomalies of lattice constants are found at the different kinds of spontaneous magnetic transitions. The transversal and longitudinal magnetostrictions of polycrystalline samples are measured in the pulse magnetic field up to 25T. In the external magnetic field there occurs a first-order field-induced antiferromagnetism－ferromagnetism transition in the Mn sublattice, which gives rise to a large magnetostriction. The magnitude of magnetostrictions is as large as 10^-3. The transversal and longitudinal magnetostrictions have the same sign and are almost equal. This indicates that the magnetostriction is isotropic and mainly caused by the interlayer Mn－Mn exchange interaction. The experimental results are explained in the framework of a two-sublattice ferrimagnet with the negative exchange interaction in one of the sublattices by taking into account the lattice constant dependence of interlayer Mn－Mn exchange interaction.     

THE PRECISE BEARING METHOD OF DIGITAL SPLIT-BEAM ARRAY SYSTEM

The precise bearing problem of digital split-beam sonar is described in this paper.By using theprinciple of cross power spectrum method proposed by Piersol for estimating the time delay between twosignals,the relationship between signal incidental angle and the time delay of equivalent acousticcenters of line or circle array are derived.Based on these expression,the precise value of bearing anglefor the target can be directly calculated from the input data. The accuracy of the estimates which depends on the number of accumulation,the length of DFTand the sample period is given.We have also described the error due to the truncating for randomsignal.The methods of improving the estimation accuracy,such as the weighting for estimates,win-dowing for input data and choosing the suitable parameters for DFT are given. The block diagram and a part of results of system simulation are presented.The method proposedin this paper is available in the real-time tracking of multiple targets of digital sonar.     

STRUCTURE AND FUNCTION OF THE SOUNDING APPARATUS IN CICADA(C.atrata Fabr.)

In C.atrata Fabr.the sounding organ is a miniaturized sound-producing apparatus with multiplexstructural combinations.Its song consists of amplitude modulated pulse trains,with repetition fre-quency at about 180 Hz.The measurable bandwith is 200—12500 Hz with the main peak at 5 kHzand a tuning sharpness(Q_3dB)of 2.2±0.4.The song is produced by vibrations of the tymbaldriven by alternating contractions of the tymbal muscles on both side.The functions of the tymbalchamber are to ameliouate the song waveform and tuning characteristics and to increase volume.The abdominal chamber further helps to improve timbre and to raise volume.The main functionof the abdominal cavity is to raise song output.The joint membrane shows obvious effects on ameliora-tion of timbre and tuning characteristics.The operculum and the mirror membrane only have alittle effect on volume regulation. The construction and the function of the cicada sounding organ may serve as some kind of biolog-ical prototype for sounding equipment des     

Magnetic Properties and magnetic phase diagrams of intermetallic compound GdMn2Ge2

A modified Yafet－Kittle model is applied to investigate the magnetic properties and magnetic phase transition of the intermetallic compound GdMn_2Ge_2. Theoretical analysis and calculation show that there are five possible magnetic structures in GdMn_2Ge_2. Variations of external magnetic field and temperature give rise to the first-order or second-order magnetic transitions from one phase to another. Based on this model, the magnetic curves of GdMn_2Ge_2 single crystals at different temperatures are calculated and a good agreement with experimental data has obtained. Based on the calculation, the H－T magnetic phase diagrams of GdMn_2Ge_2 are depicted. The Gd－Gd, Gd－Mn, intralayer Mn－Mn and interlayer Mn－Mn exchange coupling parameters are estimated. It is shown that, in order to describe the magnetic properties of GdMn_2Ge_2, the lattice constant and temperature dependence of interlayer Mn－Mn exchange interaction must be taken into account.