Continuous feedback control of KdV Burgers system

The chaos in the KdV Burgers equation describing a ferroelectric system has been successfully controlled by using a continuous feedback control. This system has two stationary points. In order to know whether the chaos is controlled or not, the instability of control equation has been analysed numerically. The numerical analysis shows that the chaos can be converted to one point by using one control signal, however, it can converted to the other point by using three control signals. The chaotic motion is converted to two desired stationary points and periodic orbits in numerical experiment separately.     

Equation of State of Spin-polarized Neutron Matter and Three-body Effect

Within the spin-dependent Brueckner-Hartree-Fock (BHF) framework, the equation of state of the spinpolarized neutron matter has been investigated by adopting the realistic nucleon-nucleon interaction supplemented with a microscopic three-body force. The three-body force has been turn out to be crucial for reproducing the empirical saturation properties of nuclear matter in a non-relativistic microscopic approach[2] such as BHF. The related physical quantities such as spin-symmetry energy, magnetic susceptibility, have been extracted. The three-body force effects have been studied and discussed with a special attention. It is found that in the whole range of spin-polarization, the cnergy per particle of spin-polarized neutron matter fulfills a quadratic relation versus the spin-polarization parameter. The calculated spin-symmetry energies as a function of densityare shown in Fig.l, where the solid curve is obtained by using the AVis two-body force plus the three-body force and the dashed curve is the result by adopting the pure AVis two-body force.     

Editorial

正The paradigm that our universe is dominated by non-luminous matter,i.e.,dark matter,rather than ordinary baryonic matter,has been established since the 1980s.However,the nature of dark matter remains almost unknown.Many ongoing space experiments are aiming at uncovering the particle nature of dark matter via precise measurements of the flux of cosmic-ray particles,with a hope to find fingerprints that tiny annihilations or decays of dark matter may have left.Such experiments     

Massive Quark Propagator in the Colour—Superconducting Phase

A more general expression for the quark propagator including both chiral and diquark condensates has been derived by using energy projectors.This makes it possible to study the phase transition from the hadron phase to the colour-superconductivity phase in the moderate baryon density region by using the Feynman diagrammatic method or the Green function method.     

Linear and Nonlinear Optical Absorptions of a Donor Impurity in Spherical Quantum Dots

An investigation of the optical properties of a hydrogenic donor in spherical parabolic quantum dots has been performed by using the matrix diagonalization method. The optical absorption coefficient between the ground （L = 0） and the first excited state （L = 1） have been examined based on the computed energies and wave functions. The results are presented as a function of the incident photon energy for the different values of the confinement strength. These results show the effects of the quantum size and the impurity on the optical absorption coefficient of a donor impurity quantum dot.     

Lambda Hypernuclei in a Chiral Hadronic Model

Nuclear matter calculations in a chiral hadronic model have been performed. It has been found that the scalar and the vector potentials and binding energies per nucleon in the chiral hadronic model are very close to those of the microscopic relativistic Brueckner-Hartree-Fock calculations. The good results for finite nuclei can be obtained in the mean field approximation only if scalar mass rns and coupling constant g8 have been improved with the fixed values of c^28 = g^28(M/rn8)^2 as those given by the original parameter sets of the chiral hadronic model. Then the chiral hadronic model is extended to lambda hypernuclei. Our results predicted by the chiral hadronic model are compared with those by the nonlinear Walecka model. It has been shown that the hadronic model can also be used to describe lambda hypernuclei successfully.     

Influence of Dzyaloshinskii-Moriya and Kaplan-Shekhtman-Entinwohlman-Aharony superexchange interactions on ground state properties of the one-dimensional spin-Peilers model in open chain

The effects of the Dzyaloshinskii-Moriya (DM) and the Kaplan-Shekhtman-Entinwohlman-Aharony (KSEA) superexchange interactions on the ground state properties of the one-dimensional spin-Peilers system in open chain are studied by using the Lanczos numerical method.The study concentrates mainly on the influence of systemic dimerisation in open chain.The results show that systemic ground state energy density varies with dimerisation parameter δ in different DM interactions,and there exists a special point δ c where the DM interaction has no influence on the systemic dimerisation,no matter whether the DM interaction is relative or irrelative to systemic dimerisation (η=1 or η=0).The KSEA interaction has no fixed special point,but the points of intersection are dense relatively in a certain numberical value range,and sparse in other numberical value ranges.So we can conclude that the antisymmetric anisotropy DM interaction differs from the symmetric anisotropy KSEA interaction,but they are analogous in the sense of the influence of systemic dimerisation in open chain.     

Three-body Effect on ^1S0 Proton and Neutron Superfluidity in Neutron stars

The proton and neutron 1S0 pairing gaps in 13-stable neutron star matter have been studied by using the isospin dependent Brueckner-Hartree-Fock approach and the BCS theory. We have concentrated on investigating and discussing the effect of three-body force. In Fig.1 is plotted the predicted neutron energy gap in the ^1S0 channel as a function of the total baryon density pB. The solid curve is obtained using the AVis interaction plus the three-body force. The dash curve is calculated by adopting the pure AVis two-body potential It isseen that the three-body force effect is quiet small, i.e., quasr negligible at relatively low density and a plight suppression as increasing density. In Fig.2 is reported the proton ^1S0 energy gap in β-stable matter. The solid curve is predicted by using the AVis plus the three-body force, the dash one by using purely the AV18 two-body force.     

Near-Threshold Low Rydberg Depletion Spectroscopy of H2, D2, and HD

Using high-resolution depletion spectroscopy, we have experimentally studied the physics of near-threshold low Rydberg states of all three stable isotopic variants of molecular hydrogen. The experiments were required to calibrate the absolute wavelength, including several transitions from the EF (v = 0) and EF (v = 6 or v = 9) to the same low-n Rydberg states. The measurements have been performed for several initial rotational levels in all three stable isotopic variants. Transitions to very high vibrational levels of the B, Bt, and C states have been measured with accuracy 0.002cm^-1. The pulsed amplifier perturbations were also measured by opticalhe terodyne methods.     

Beam combining of a high-power laser diode bar on a temperature gradient heat sink

A new wavelength beam combining technique for a high-power laser diode bar by using a temperature gradient heat sink has been proposed. The thermal controlling principle of the temperature heat sink has been discussed. It has been proved by experiment that the linear temperature distribution, which generates linear wavelength spread of the output beams from a LD bar, can be obtained by introducing a temperature gradient heat sink and the output beams can be focused into a relative small spot by using the Czerny-Turner beam shaping system.     

Matter Collineations in Kantowski-Sachs, Bianchi Types I and III Spacetimes

The matter collineation classifications of Kantowski-Sachs, Bianchi types I and III space times are studied according to their degenerate and non-degenerate energy-momentum tensor. When the energy-momentum tensor is degenerate, it is shown that the matter collineations are similar to the Ricci collineations with different constraint equations. Solving the constraint equations we obtain some cosmological models in this case. Interestingly, we have also found the case where the energy-momentum tensor is degenerate but the group of matter collineations is finite dimensional. When the energy-momentum tensor is non-degenerate, the group of matter collineations is finite-dimensional and they admit either four which coincides with isometry group or ten matter collineations in which four ones are isometries and the remaining ones are proper.     

Symmetries of Type D Pure Radiation Fields

The geometrical symmetries corresponding to the continuous groups of collineations and motions generated by a null vector l are considered. These symmetries have been translated into the language of Newman-Penrose formalism for pure radiation (PR) type D fields. It is seen that for such fields, conformal, special conformal and homothetic motions degenerate to motion. The concept of free curvature, matter curvature and matter affine collineations have been introduced and the conditions under which PR type D fields admit such collineations have been obtained. Moreover, it is shown that the projective collineation degenerate to matter affine, special projective, conformal, special conformal, null geodesic and special null geodesic collineations. It is also seen that type D pure radiation fields admit Maxwell collineation along the propagation vector l.     

Classification of Spherically Symmetric Static Spacetimes According to Their Matter Collineations

The spherically symmetric static spacetimes are classified according to their matter collineations. These are investigated when the energy-momentum tensor is degenerate and also when it is non-degenerate. We have found a case where the energy-momentum tensor is degenerate but the group of matter collineations is finite. For the non-degenerate case, we obtain either four, five, six or ten independent matter collineations in which four are isometries and the rest are proper. We conclude that the matter collineations coincide with the Ricci collineations but the constraint equations are different which on solving can provide physically interesting cosmological solutions.     

Ricci Collineations in Perfect Fluid Bianchi V Spacetime

The Bianchi V spacetimes with perfect-fluid matter are classified according to their Ricci collineations. We have found that in the degenerate case there are infinitely many Ricci collineations whereas a subcase gives a finite number of Ricci collineations which are five. In the non-degenerate case the group of Ricci collineations is finite, i.e. four or five or six or seven. Also, all results obtained satisfy the energy conditions.     

Conformal Ricci Collineations of Static Spherically Symmetric Spacetimes

Conformal Ricei collineations of static spherically symmetric spacetimes are studied. The general form of the vector fields generating eonformal Rieei eollineations is found when the Rieei tensor is non-degenerate, in which ease the number of independent eonformal Rieei eollineations is 15, the maximum number for four-dimensional manifolds. In the degenerate ease it is found that the static spherically symmetric spaeetimes always have an infinite number of eonformal Rieei eollineations. Some examples are provided which admit non-trivial eonformal Rieei eollineations, and perfect fluid source of the matter.     

Curvature and Weyl collineations of Bianchi type V spacetimes

The objective of this paper is twofold: (a) First the curvature collineations of the Bianchi type V spacetimes are studied using rank argument of curvature matrix. It is found that the rank of the 6×6 curvature matrix is 3, 4, 5 or 6 for these spacetimes. In one of the rank 3 cases the Bianchi type V spacetime admits proper curvature collineations which form infinite dimensional Lie algebra. (b) Then the Weyl collineations of the Bianchi type V spacetimes are investigated using rank argument of the Weyl matrix. It is obtained that the rank of the 6×6 Weyl matrix for Bianchi type V spacetimes is 0, 4 or 6. It is further shown that these spacetimes do not admit proper Weyl collineations, except in the trivial rank 0 case, which obviously form infinite dimensional Lie algebra. In some special cases it is found that these spacetimes admit Weyl collineations in addition to the Killing vectors, which are in fact proper conformal Killing vectors. The obtained conformal Killing vectors form four-dimensional Lie algebra.     

General symmetries of a string fluid space-time

It is shown that a string fluid is the simplest anisotropic fluid with vanishing heat flux. Furthermore it has the property that the Ricci tensor is obtained from the energy momentum tensor, and vice versa, if one interchanges the fluid variables. We use previous works on the collineations of anisotropic fluids, which include the string fluid as a particular case, to compute the kinematic and the dynamic effects of certain collineations of a string fluid. It is found that the possible spacetimes, which can carry a string fluid, are severely restricted and the possible string fluids in spacetimes, which can admit them are more or less fixed. We recover previous results on the effect of symmetries in string fluid spacetimes and get many new ones, for example the matter inheritance collineations. The study and the results are presented in a systematic manner, which allows the comprehension and the comparison of the restrictions imposed by each collineation. Finally one can use the same method of work for a systematic study of similar problems.     

Matter collineation classification of Bianchi type II spacetime

In this paper we classified the matter collineations (MCs) of Bianchi type II spacetime according to the degenerate and non-degenerate energy-momentum tensor. It is shown that when the energy-momentum tensor is degenerate, most of the cases yield infinite dimensional MCs whereas some cases give finite dimensional Lie algebras in which there are three, four or five MCs. For the non-degenerate matter tensor cases we obtained that the Lie algebra of MCs is finite dimensional, in which the number of MCs are also three, four or five. Furthermore, we discussed the physical implications of the obtained MCs in the case of perfect fluid as source.     

Ricci Collineations of Static Space Times with Maximal Symmetric Transverse Spaces

A complete classification of static space times with maximal symmetric transverse spaces is provided, according to their Ricci collineations. The classification is made when one component of Ricci collineation vector field V is non-zero (cases 1～4), two components of V are non-zero (cases 5～10), and three components of V are non-zero (cases 11～14), respectivily. Both non-degenerate (det R_ab ≠0) as well as the degenerate (det R_ab=0) cases are discussed and some new metrics are found.