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Convergence for Imaginary Time Step evolution in the Fermi and Dirac seas

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Science China(physics,Mechanics & Astronomy) 2010年第2期53卷 327-330页

作者： LI FangQiong1,ZHANG Ying2 & MENG Jie2,3,4 1Guizhou university for Nationalities,Guiyang 550025,China 2State Key Lab Nucl. Phys. & Tech.,School of physics,Peking university,Beijing 100871,China 3School of physics and Nuclear Energy Engineering,Beihang university,Beijing 100191,China 4department of physics,university of stellenbosch,stellenbosch,south africa 1. Guizhou university for Nationalities Guiyang 550025 China2. State Key Lab Nucl. Phys. & Tech. School of Physics Peking University Beijing 100871 China3. School of Physics and Nuclear Energy Engineering Beihang University Beijing 100191 China4. Department of Physics University of Stellenbosch Stellenbosch South Africa

The convergence for the Imaginary Time Step (ITS) evolution with time step is investigated by performing the ITS evolution for the Schrdinger-like equation and the charge-conjugate Schrdinger-like equation deduced from Dirac equation for the single proton levels of 12C in both the Fermi and Dirac seas. For the guaranteed convergence of the ITS evolution to the "exact" results,the time step should be smaller than a "critical" time step Δtc for a given single-particle level. The "critical" time step Δtc is more sensitive to the quantum numbers |κ| than to the energy of the single-particle level. For the single-particle levels with the same κ,their "critical" time steps are in the same order. For the single-particle levels with similar energy,a relatively small (large) "critical" time step for larger (smaller) |κ| is needed. These conclusions can be used in the future self-consistent calculation to optimize the evolution procedure.

关键词： Dirac equation Schrdinger-like equation Imaginary Time Step method convergence

Optimization of the imaginary time step evolution for the Dirac equation

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Science China(physics,Mechanics & Astronomy) 2011年第2期54卷 231-235页

作者： LI FangQiong1,ZHANG Ying2,LIANG HaoZhao2,3 & MENG Jie4,2,5 1Guizhou university for Nationalities,Guiyang 550025,China 2State Key Lab Nuclear physics & Technology,School of physics,Peking university,Beijing 100871,China 3Institut de Physique Nucle’aire,IN2P3-CNRS and Universite’ Paris-Sud,F-91406 Orsay Cedex,France 4School of physics and Nuclear Energy Engineering,Beihang university,Beijing 100191,China 5department of physics,university of stellenbosch,stellenbosch,south africa 1. Guizhou university for Nationalities Guiyang 550025 China2. State Key Lab Nuclear Physics & Technology School of Physics Peking University Beijing 100871 China3. Institut de Physique Nucléaire IN2P3-CNRS and Université Paris-Sud F-91406 Orsay Cedex France4. School of Physics and Nuclear Energy Engineering Beihang University Beijing 100191 China5. Department of Physics University of Stellenbosch Stellenbosch South Africa

Taking the single neutron levels of 12C in the Fermi sea as examples,the optimization of the imaginary time step(ITS) evolution with the box size and mesh size for the Dirac equation is *** the weakly bound states,in order to reproduce the exact single-particle energies and wave functions,a relatively large box size is *** long as the exact results can be reproduced,the ITS evolution with a smaller box size converges faster,while for both the weakly and deeply bound states,the ITS evolutions are less sensitive to the mesh ***,one can find a parabola relationship between the mesh size and the corresponding critical time step,i.e.,the largest time step to guarantee the convergence,which suggests that the ITS evolution with a larger mesh size allows larger critical time step,and thus can converge faster to the exact *** conclusions are very helpful for optimizing the evolution procedure in the future self-consistent calculations.

关键词： Dirac equation Schrdinger-like equation imaginary time step method convergence

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中共二十届三中全会为非洲发展带来重大机遇

当代世界 2024年第8期 78-79页

作者： [南非]谭哲理南非哲理中非国际交流智库

2024年7月15—18日,中国共产党第二十届中央委员会第三次全体会议召开,审议通过了《中共中央关于进一步全面深化改革、推进中国式现代化的决定》(下称《决定》)。中共中央总书记习近平作了重要讲话。作为平等伙伴关系下的朋友和兄弟,非... 详细信息

2024年7月15—18日,中国共产党第二十届中央委员会第三次全体会议召开,审议通过了《中共中央关于进一步全面深化改革、推进中国式现代化的决定》(下称《决定》)。中共中央总书记习近平作了重要讲话。作为平等伙伴关系下的朋友和兄弟,非洲国家认识到,中共二十届三中全会及其决定不仅对中国意义重大,也为非中合作带来更多机遇。

关键词：中国式现代化中共中央总书记全面深化改革三中全会重大机遇《决定》中央委员会习近平

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Micromorphology of Surface Crusts in the Knersvlakte,south africa

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Journal of Mountain Science 2009年第2期6卷 189-196页

作者： Sarah-Jane C.Fox Anthony J.Mills Rosa M.Poch department of Soil Science Stellenbosch UniversityStellenbosch South Africa department of Environment and Soil Science University of LleidaRovira Roure 191 Lleida

Soils in the Knersvlakte are particularly prone to crusting and have lower inherent infiltrability than other soils across western southern africa. Micromorphological techniques were used to examine the structure and porosity of soil crusts in the Knersvlakte to ascertain why crusting is so intense in this region. Quantile regression using boundary lines was employed to examine the relationships between infiltrability and soil properties for all samples （n = 67）. This analysis showed that infiltrability is potentially maximal at low water- dispersible ＇clay plus silt＇ content and low silt content （r^2 = 0.72 and 0.64; respectively, n = 67）（Figure 2）. The strength of crusts, pH, EC, clay mineralogy, and water-dispersible clay, silt and ＇clay plus silt＇ content were compared, and a pore analysis using optical microscopy was undertaken on images of six soil thin sections （n = 6）（circular and parallel polarizers）. Pore analysis was further undertaken on five horizontal slices of equal dimensions taken through each soil thin section. The porosity samples with low infiltrability （〈 100 mm·hr^-1, n = 4） had greater crust strength, lower porosity （both total and in the least porous slice） and greater water-dispersible ＇day plus silt＇ and silt content than the porosity samples with high infiltrability （〉 100mm·hr^-1, n = 2）. The porosity samples with low infiltrability showed a trend of lower pH and greater water dispersible clay percentage. Porosity varied within the porosity samples due to the presence of dense clay/silt bands （〈 0.5 mm in width） with relatively few air vesicles. The porosity samples with horizontal slices of low porosity （but large numbers of air vesicles） had low infiltrability, while those without slices of low porosity （and relatively few air vesicles） had high infiltrability. We conclude that the intense crusting and resultant low infiltrability of soils in the Knersvlakte appears to be related to the formation of thin, dense clay/silt bands in the

关键词： Infiltrability optical microscopy porosity air vesicles

X-ray spectra induced by ^(129)Xe^(q+) impacting the metal surface

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Science China(physics,Mechanics & Astronomy) 2008年第1期51卷 82-89页

作者： ZHANG XiaoAn 1,2 ,XIAO GuoQing 1 ,YANG ZhiHu 1 ,CHEN XiMeng 3 ,ZHAO YongTao 1 , LI FuLi 4 ,WANG Li 1,2 ,CUI Ying 3 ,ZHANG HongQiang 3 &ZHAN WenLong 1 1Institute of Modern physics,Chinese Academy of Sciences,Lanzhou 730000,China 2department of physics,Xianyang Normal university,Xianyang 712000,China 3department of Modern physics,Lanzhou university,Lanzhou 730000,China 4department of Applied physics,Xi’an Jiaotong university,Xi’an 710049,China 1. Institute of Modern physics Chinese Academy of Sciences Lanzhou 730000 China 2. department of physics Xianyang Normal University Xianyang 712000 China 3. department of Modern physics Lanzhou University Lanzhou 730000 China 4. department of Applied physics Xi’an Jiaotong University Xi’an 710049 China

Using the slow highly charged ions 129 Xe q+ (q=25,26,27;initial kinetic T0≤4.65 keV/a.u.)to impact Au surface,the Au atomic Mαcharacteristic X-ray spectrum is *** result shows that as long as the charge state of projectile is high enough,the heavy atomic characteristic X-ray can be effectively excited even though the incident beam is very weak(nA magnitude),and the X-ray yield per ion is in the order of 10-8and increases with the kinetic energy and potential energy of *** measuring the Au Mα-X-ray spectra,Au atomic N-level lifetime is estimated at about 1.33×10-18s based on Heisenberg uncertainty relation.

关键词： slow highly charged ions characteristic X-ray level lifetime

Structure analysis of ^(159)Sm and properties of odd-mass neutron-rich nuclei in mass-160 region

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Science China(physics,Mechanics & Astronomy) 2011年第S1期54卷 81-87页

作者： YANG YingChun1 & SUN Yang1,2,3 1 department of physics, Shanghai Jiao Tong university, Shanghai 200240, China 2Institute of Modern physics, Chinese Academy of Sciences, Lanzhou 730000, China 3department of physics and Astronomy, university of Tennessee, Knoxville, Tennessee 37996, USA 1. department of physics Shanghai Jiao Tong University Shanghai 200240 China2. Institute of Modern Physics Chinese Academy of Sciences Lanzhou 730000 China3. Department of Physics and Astronomy University of Tennessee Knoxville Tennessee 37996 USA

Recent fission experiment data provide interesting structure information for neutron-rich nuclei in the mass A ～ 160 region. We apply the projected shell model to study the strongly-deformed, neutron-rich Sm isotopes. We perform calculations for rotational bands up to spin I = 20 (29/2) for even-even (odd-neutron) Sm isotopes, and analyze the band structure of low-lying states with quasiparticle excitations. Emphasis is given to rotational bands based on one-quasiparticle (1-qp) configurations in the odd-mass 159Sm. The 159 Sm result is discussed together with those of the even-even isotopes 158,160Sm. New bands in 159Sm based on neutron 1-qp 1/2 and 5/2+ configurations are predicted. Electromagnetic transition probabilities are discussed.

关键词： projected shell model neutron-rich nuclei low-lying excitations isomeric states

Direct CP violation in hadronic B decays

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Science China(physics,Mechanics & Astronomy) 2006年第3期49卷 357-366页

作者： HONG Bihai1,2 & Lü Caidian3 1. department of physics, Lishui university, Lishui 323000,China 2. department of physics, Shanghai Jiaotong university, Shanghai 200030, China 3. Institute of High Energy physics, Beijing 100049,China department of physics Lishui University Lishui 323000 China department of physics Shanghai Jiaotong University Shanghai 200030 China Institute of High Energy physics Beijing 100049 China

There are different approaches for the hadronic B decay calculations, recently. In this paper, we upgrade three of them, namely factorization, QCD factorization and the perturbative QCD approach based on kT factorization, using new parameters and full wave functions. Although they get similar results for many of the branching ratios, the direct CP asymmetries predicted by them are different, which can be tested by recent experimental measurements of B factories.

关键词： CP violation hadronic B decay factorization.

The phase transition and classification of critical points in the multistability chemical reactions

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Communications in Nonlinear Science and Numerical Simulation 2000年第1期5卷 36-43页

作者： Chunhua ZHANG Fugen WU Chunyan WU and Fa OU department of physics, Guangdong university of Technology, Guangzhou510090, China department of Applied physics, south China university of Technology, Guangzhou 510641, China department of physics Guangdong University of Technology Guangzhou 510090 China department of Applied physics South China University of Technology Guangzhou 510641 China

In this paper, we study the phase transition and classification of critical points in multistability chemical reaction systems. Referring to the spirit of Landau's theory of phase transitions, this paper deals with the varied transitions and critical phenomena in multistable chemical systems. It is demonstrated that the higher the order of the multistability, the wider the variety of phase transitions will be. A classification scheme of critical points according to the stability criterion and the thermodynamic potential continuity is suggested. It is useful for us to study critical phenomena especially in the non-equilibrium systems including the multi-Stable chemical ones.

关键词： nonlinear chemistry non-equilibrium phase transition critical points

Study on the two and three-parameter working stability regions of 3Y-TZP suspension

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Science China(Technological Sciences) 2006年第5期49卷 547-568页

作者： CHEN Youqiang1, 2, ZHANG Xinni3, CHEN Sha’ou3 & QI Ping3 1. department of Chemistry, Qingdao university, Qingdao 266071, China 2. department of Chemistry, Tsinghua university, Beijing 100084, China 3. department of physics, Qingdao university, Qingdao 266071, China 1. department of Chemistry Qingdao University Qingdao 266071 China 2. department of Chemistry Tsinghua University Beijing 100084 China 3. department of physics Qingdao University Qingdao 266071 China

We determined the variation tendency of viscosity (η) at various solids load- ing (α) for 3Y-TZP suspension as a function of dispersant concentration (Cw) using vis- cosity measurement, measured the diameter of particles as a function of Cw in very dilute suspension using light scattering method, and obtained the surface features of the sedi- ment of suspension with different Cw using SEM. We also discussed the influence of the microstructure of adsorbed polymer layers on particles and their interactions in the dis- persing medium on the stability of suspension. Then two different stable states and two different unstable states for 3Y-TZP suspension were given. Accordingly, the (Cw, η), (Cw, α), and (α, η) two-parameter, and (Cw, α, η) three-parameter stability maps were con- structed. Based on the DLVO theory calculations, the dispersant concentration, particle distance (r), and interparticle potential energy (VT) maps with various solids loading for 3Y-TZP aqueous suspension were also constructed. In (Cw, r) two-parameter coordinate system, the stable motion region map for particles was established. The Cw, α, and VT,max (the highest potential energy) surface of the potential barrier map was obtained through calculation and simulation on the basis of the surfaces of Cw, r, VT maps introduced above. The (Cw, α) two-parameter stability map was then obtained from the Cw, α, VT,max map. The results showed that this theoretical map can qualitatively prove the experimentally obtained results—the existence of different dispersed states of particles in suspension system and the variation tendency of suspension stability with changing each parame- ter—were reasonable.

关键词： 3Y-TZP, suspension, stability, DLVO theory, interparticle potential energy.