缓建京沪高速铁路

关于京沪高铁,现在众说纷坛.有说日本引进,有说德、法、意引进,偶见经济技术和政治外交精心角逐.有说当用摆式机车,有说需用轮轨技术,有说可用磁悬浮式,现在像是倾向轮轨技术.在投资规模方面,有说1300亿,有说2000亿,有说3000亿.有说缓建一年损失200亿,有说京沪线现有运力还大有潜力可挖,并没有饱和.是建、不建还是缓建,据说不久将有决策.虽然京沪高铁的修建与否争论已久,但并没有发现要修建的必然理由.目前,修建京沪高铁不是促进经济和谐快速发展的好时机.最好的时机还没有到来,京沪高铁的修建还需要准备和等待.京沪高铁的决策需三思而后行.

极端条件下原子核中对关联的一种处理方法

对关联是原子核中最重要的剩余相互作用．阐述了用多体关联方法研究原子核中对关联效应的可能性，并以中子晕核11Li、11Be为例，阐述了此方法的可行性．

用相对论性密度依赖Hartree方法研究两体关联在晕核中的效应

用相对论性密度依赖的 Hartree方法研究晕核的基本性质 ,在晕核的唯象图景中 ,作为剩余相互作用的对关联效应对核晕的描述有关键作用 .用只有一个自由参数的模型 ,同时给出了晕核11Li,11Be和 19C的分离能和质量密度分布 。

Deexcitation Energy of Superdeformed Secondary Minima as a Probe to Density Dependence of Symmetry Energy

Deexcitation energies of superdeformed secondary minima of odd-odd Au and Tl isotopes are investigatedwith the relativistic mean field (RMF) model where the isoscalar-isovector coupling is included to change the symmetryenergy.It is verified by the theoretical analysis and numerical results that the deexcitation energies of superdeformedsecondary minima relative to the ground states in these heavy nuclei are sensitive to differences in the symmetry energy.In particular, the linear correlation between the deexcitation energies of odd-odd Au and Tl isotopes and the neutron skinthickness in ^(208)Pb is established.Moreover, explorations are extended to superdeformed candidates of other mass regions.It is found that the linear correlation can even be established between the deexcitation energies and the symmetry pressureat subsaturation density.These indicate that deexcitation energies can serve as a probe to the density dependence ofthe symmetry energy.

Dilepton Production in an Expanding Hot Baryon-Rich Quark-Gluon Matter

Under thermodynamic equilibrium, the initial values of the quark-gluon system from relativistic nucleus-nucleus collisions are obtained. From these initial values we have studied the dilepton production on the basis of the relativistic hydrodynamic model, and found that with increasing incident energy a characteristic plateau indicating the formation of the quark-gluon plasma appears in the total yield.

Medium Effects on Dynamical Properties of the Fermion and Mesons in the Gauged Nambu- Jona-Lasinio Model

The gap equation for the fermion in the gauged Nambu-Jona-Lasinio(NJL)model is derived in nuclear medium with flavors Nf=2.Based on the gap equation,the fermion mass in nuclear medium is obtained and used to determine the properties of the scalar and pseudoscalar mesons.In contrast to the NJL model,the gluonic part has the one-fourth contribution to the fermion mass.The critical density with the chiral symmetry restored is about 6ρ0.

De-excitation Energy of Superdeformed Secondary Minima of Odd-Odd Au Isotopes and Its Sensitivity to the Density Dependence of Symmetry Energy

The de-excitation energy of superdeformed secondary minima of odd-odd Au isotopes is investigated using the relativistic mean field model with the inclusion of the isoscalar-isovector coupling. It is shown that the de-excitation energies of superdeformed secondary minima relative to the ground states can serve as a significant probe to the density dependence of the symmetry energy.

Charge Density of ^23,24O with Isoscalar-Isovector Coupling Terms

The nonlinear isoscalar-isovector terms which are used to simulate the density dependence of the symmetry energy are considered in the relativistic mean field model. The charge density distributions of ^23,24O are investigated by considering the contribution from the isoscalar-isovector couplings. Contrarily to the uncertainty of the neutron radius of ^208Pb, a considerable uncertainty exists for the charge radii of ^23,24O. The data-to-data correlation between the neutron thickness of ^208Pb and that of ^23,24O is enhanced by the inclusion of the pNN tensor coupling. This enhancement is closely related to the structural factor, the 2s1/2 occupation of the out-layer neutrons.

Heating of Nanosized Liquid Water in High-Intensity Terahertz Pulses

Non-equilibrium molecular dynamics simulations of liquid water in picosecond high-power terahertz pulses are performed by using a non-polarizable potential model. Numerical results show that the energy absorption of water molecules exhibits a pronounced resonance with THz pulses in the frequency range of 14-17 THz. With the THz pulse at resonant frequencies, the maximum temperature is about 562 K by heating the water at room temperature. Further investigation indicates that the results are independent of the size of the nanoscale water box. The efficiency of energy transfer by resonant absorption is more than seven times of microwave heating. These studies show promising applications of ultrashort THz pulses.

Intermediate Mass Dilepton Production in an Expanding Baryon-rich Quark--Gluon Matter

The intermediate mass dileptons from the quark phase,secondary hadronic processes and background sources have been studied based on a relativistic hydrodynamic model.Due to the effect of the phase boundary on the evolution of the system the contribution from the quark phase is much more important than that from secondary processes and is even comparable with that from background sources.This leads to a spectrum without the obvious humps of the hadronic phase contribution and the yield increasing with the incident energy of colliding nuclei.It is shown that the enhancement of dileptons is a signature for the formation of the quark--gluon plasma.

Total Reaction Cross Section Measurements at Intermediate Energy for the Proton Halo Candidate ^(23)Al and Its Neighbours

Total reaction cross sections σR for some proton-rich isotones (N = 10) near ^(23)Al on a carbon target have been measured at intermediate energies in the experiment performed at the Radioactive Ion Beam Line of the Heavy Ion Research Facility in Lanzhou. The Z-dependence of σR shows a remarkable enhancement for ^(23)Al relative to its neighbours. The difference factor d has been deduced from the measured σR by using the Glauber or Boltzmann-Uehling-Uhlenbeck models. From the above analysis, a possible one-proton halo structure is suggested for ^(23)Al.

Dilepton Production in an Expanding Hot Baryon-Rich Quark-Gluon Matter

From the full stopping scenario,a relativistic hydrodynamic model describing the evolution of the baryon-rich quark-gluon matter fire-cylinder has been established.Based on it,the rapidity Distribution of dileptons with intermediate invariant masses has been studied.It is found that the quark phase gives the dominant contribution to the dilepton spectrum due to the influence of the phase boundary on the evolution of the system,especially the dilepton yield is strongly suppressed with the increasing rapidity.

Neutron star core-crust transition and the crustal moment of inertia in the nonlinear relativistic Hartree approximation

We investigate the effects of theσmeson mass(m_(σ)),symmetry energy,and slope of the symmetry energy on the neutron star core-crust transition density and the crustal moment of inertia(ΔI/I)in the nonlinear relativistic Hartree approach(RHA),which includes vacuum polarization.Although the core-crust transition density(ρ_(t)),pressure(P_(t)),and neutron star radius(R),which are all dependent on the symmetry energy,contribute to determiningΔI/I,we find that changing only the slope of symmetry energy within a reasonable range is not sufficient to reachΔI/I≥7%to achieve the large glitches of the Vela pulsar.However,since all three factors(ρ_(t),P_(t),and R)increase with the increase in mσthrough scalar vacuum polarization,adjusting mσcan easily achieveΔI/I≥7%.

柱环腔中的量子电动力学效应

研究以同轴不同半径柱面围成的导体柱环腔体中电磁场真空零点振动模式所给出的宏观量子效应 .零点振动模式通过求解柱环空腔边界条件下无源的Maxwell方程组获得 .得到了双柱面同心柱环中单位长度和单位面积的且是有限的真空能量 ,即Casimir能量 .这有限的Casimir能量可以分解为独立而且收敛的三部分 ,它们分别来自内柱面、外柱面和柱环之中 .对多柱面同心柱环 ,Casimir能量可分解为独立的 (2n— 1)部分 (n为柱面数 ) .柱环是类似于平行板的几何结构 .但柱环所给出的Casimir能量和Casimir势能系数是随着柱环间隔变化的 ,不同于平行板是常数的情况 .