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A New Type of Accessible Environmental Influences on Neutrino Oscillation

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Communications in Theoretical Physics 2001年第5期35卷 557-562页

作者： changchao－hsi DONGHUi－Shi 等 InstituteofTheoreticalPhysics AcademiaSinicaP.O.Box2735Beijing100080China DepartmentofPhysics NankaiUniversityTianjin300071China

Considering a new type of environment influences, we use a two-energy-level quantum system to investigate neutrino oscillations in medium. Besides the matter effects derived by Wolfenstein, there may exist extra terms due to a unitary evolution of the system between pure and mixed states, so the evolution equation is modified obviously. We show that the extra terms may play some role and induce observable effects in solar neutrino problem, especially, in the long baseline neutrino oscillation experiments which are under serious consideration recently, if the parameters fall into a suitable region.

关键词： neutrino oscillation pure and mixed states extra medium effects

Study of the Bc—Meson Lifetime

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Communications in Theoretical Physics 2001年第1期35卷 57-60页

作者： changchao－hsi CHENShao－Long 等 CCAST（WorldLabortory） P.O.Box8730Beijing100080China InstituteofTheoreticalPhysics theChineseAcademyofSciencesBeijing100080China DepartmentofPhysics NankaiUniversityTianjin300

We in terms of optical theorem estimate the lifetime of Bc meson with the parameters which are determined by fitting the data for the lifetimes and inclusive semileptonic decays of various B and D mesons. In the estimation, we find that the bound-state effects are important, and take them into account carefully in the framework which attributes the effects to the effective masses of the decay heavy quarks in the inclusive processes. We also find that to Bc lifetime the penguin contribution is enhanced due to possible interference between the penguin and the 'tree part' c1O1 + c2O2.

关键词： B-c meson lifetime

Semileptonic Decays of Bc Meson to a P—Wave Charmonium State χc or hc

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Communications in Theoretical Physics 2001年第4期35卷 395-398页

作者： changchao－hsi WANGGuo－Li 等 CCAST（WorldLaboratory） P.O.Box8730Beijing100080China InstituteofTheoreticalPhysics AcademiaSinicaP.O.Box2735Beijing100080China DepartmentofPhysics FujianNormalUniversityFuzhou

The semileptonic decays of meson Bc to a P-wave charmonium state χc(3PJ) or hc(1P1)are *** results show that the decays are sizable so they are accessible in Tevatron and LHC,especially,with the detectors LHCB and BTeV in the foreseeable future,and of them,the one to the 1P1 charmonium state potentially offers us a novel window to see the unconfirmed hc *** addition,it is pointed out that since the two charmonium radiative decays χc (3P1,2)→J/ψ+γ have sizable branching ratios,the cascade decays of the concerned decays and the charmonium radiative decays may affect the result of observing Bc meson through the semileptonic decays Bc→J/ψ+l+vl substantially.

关键词： Bc介子半轻子衰变 χc态 hc态

Nonperturbative Aspects of Axial Vector Vertex

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Communications in Theoretical Physics 2002年第4期37卷 461-464页

作者： ZONGHong－Shi changchao－hsi 等 DepartmentofPhysics NanjingUniversityNanjing210093China CCAST（WorldLaboratory） P.O.Box8730Beijing100080China

It is shown how the axial vector current of current quarks is related to that of constituent quarks within the framework of the global color symmetry *** dressing of the axial vector vertex and the quark self-energy functions are described by the inhomogeneous Bethe-Salpeter equation in the ladder approximation and the Schwinger Dyson equation in the rainbow approximation,respectively.

关键词： nonperturbative QCD constituent quark spontaneous chiral symmetry breaking

On Possible S-Wave Bound States for an N-↑N System Within a Constituent Quark Model

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Communications in Theoretical Physics 2005年第2期43卷 275-282页

作者： changchao-hsi PANGHou-Rong InstituteofTheoreticalPhysics theChineseAcademyofSciencesP.O.Box2735Beijing100080China／／CCAST（WorldLaboratory）P.O.Box8730Beijing100080China DepartmentofPhysics SoutheastUniversityNanjing210096China

We try to apply a constituent quark model (a variety chiral constituent quark model) and the resonating group approach for the multi-quark problems to compute the effective potential between the NN- in S-wave (the quarks in the nucleons N and N-, and the two nucleons relatively as well, are in S wave) so as to see the possibility if there may be a tight bound state of six quarks as indicated by a strong enhancement at threshold of pp- in J/ψ and B decays. The effective potential which we obtain in terms of the model and approach shows if the experimental enhancement is really caused by a tight S-wave bound state of six quarks, then the quantum number of the bound state is very likely to be I = 1, JPC= 0-+.

关键词： nucleon-antinucleon effective interaction multiquark system constituentquark model

Non-spectator Contributions to Lifetime of ∧b

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Communications in Theoretical Physics 2004年第5X期42卷 723-734页

作者： changchao-hsi GUOPeng LIXue-Qian WANGGuo-Li InstituteofTheoreticalPhysics AcademiaSinicaP.O.Box2735Beijing100080China DepartmentofPhysics NankaiUniversityTianjin300071China

In this work, we study the contributions of non-spectator effects to the lifetimes of Λb and B-mesons comparatively. Based on the well-established theoretical framework about the effective weak Lagrangian, we derive the formulation of the non-spectator effects at the quark level. Especially, for Λb we have considered two pictures: the three-valence-quark picture and the quark-diquark picture. In the two pictures, the interference contributions to the total width are different, in this work, we investigate the interference effects in detail. As a preliminary estimate on the lifetimes, we evaluate the hadronic matrix elements appearing in the final formulas of the lifetimes by means of a simple phenomenological model for both pictures. Our results show that the contributions of the non-spectator effects can reduce the ratio of lifetime of Λb to that of B-mesons by 5 ～ 7%. It is noted that in the quark-diquark picture the ratio can be further reduced if excited states of the diquark system are taken into account. We conclude that the measured ratio τ(Λb)/τ(B0)(≈)0.79 [The Data Group, Phys. Rev. D66 (2002) 010001] can be partly understood by the non-spectator effects, although the problem on the discrepancy between theoretical prediction and experimental measurement is not fully solved.

关键词：寿命粒子物理学重夸克效应衰退轨道

Instantaneous Bethe-Salpeter Equation and Its Exact Solution

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Communications in Theoretical Physics 2005年第1期43卷 113-118页

作者： changchao-hsi CHENJiao-Kai LIXue-Qia WANGGuo-Li CCAST（WorldLaboratory） P.O.Box8730Beijing100080China／／InstituteofTheoreticalPhysicstheChineseAcademyofSciencesP.O.Box2735Beijing100080China InstituteofTheoreticalPhysics theChineseAcademyofSciencesP.O.Box2735Beijing100080China／／GraduateSchooloftheChineseAcademyofSciencesBeijing100039China CCAST（WorldLaboratory） P.O.Box8730Beijing100080China／／DepartmentofPhysicsNankaiUniversityTianjin300071China DepartmentofPhysics NankaiUniversityTianjin300071China／／DepartmentofPhysicsFujianNormalUniversityFuzhou350007China

We present an approach to solve Bethe-Salpeter (BS) equations exactly withoutany approximation if the kernel of the BS equations exactly is instantaneous, and take positroniumas an example to illustrate the general features of the exact solutions. The key step for theapproach is from the BS equations to derive a set of coupled and well-determined integrationequations in linear eigenvalue for the components of the BS wave functions equivalently, which maybe solvable numerically under a controlled accuracy, even though there is no analytic solution. Forpositronium, the exact solutions precisely present corrections to those of the correspondingSchrodinger equation in order υ~1 (υ is the relative velocity) for eigenfunctions, in order υ~2for eigenvalues, and the mixing between S and D components in J~(PC) = 1~(--) states etc.,quantitatively. Moreover, we also point out that there is a questionable step in some existentderivations for the instantaneous BS equations if one is pursuing the exact solutions. Finally, weemphasize that one should take the O(υ) corrections emerging in the exact solutions into accountaccordingly if one is interested in the relativistic corrections for relevant problems to the boundstates.

关键词： instantaneous BS equation exact solutions positronium relativisticcorrections

中空连续体机械臂的设计与主从任务转换避障控制

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天津大学学报（自然科学与工程技术版） 2025年第1期58卷 24-35页

作者：万淑敏孙长超袁培康常乐康荣杰天津大学机构理论与装备设计教育部重点实验室天津300350

连续体机械臂具有优良的弯曲性能和柔顺灵活性,表现出了独特的环境适应性和人机交互安全性,在微创手术、灾后救援、狭窄空间检修等非结构化环境及家庭服务领域具有广阔的应用前景.然而,连续体机械臂的中央脊椎骨占据其内部空间,模块单... 详细信息

连续体机械臂具有优良的弯曲性能和柔顺灵活性,表现出了独特的环境适应性和人机交互安全性,在微创手术、灾后救援、狭窄空间检修等非结构化环境及家庭服务领域具有广阔的应用前景.然而,连续体机械臂的中央脊椎骨占据其内部空间,模块单元冗余且运动耦合导致避障运动困难等问题妨碍了其在实际场景中的应用.针对以上问题,设计了内部中空的丝驱动连续体机械臂,为末端执行器的电液气管线留置出了充足的物理空间,并通过鲍登管在结构上实现了模块单元间的运动解耦;考虑丝驱动连续体机械臂的弯曲特性,建立了解耦后的简化运动学模型和运动学闭环控制算法;构造了评估空间障碍物与连续体机械臂最短距离的计算方法;在传统变构型避障运动控制的基础上,提出了基于主从任务转换的避障控制算法,能够在末端轨迹跟踪约束下,实现对障碍的躲避,同时也可暂时舍弃对给定末端轨迹的跟踪以躲避位于末端运动轨迹附近的障碍物.仿真和实验结果表明:所设计的连续体机械臂具有良好的运动能力,轨迹跟踪控制的末端位置平均误差为2.510 mm,仅为连续体机械臂长度的0.32%;提出的主从任务转换避障控制算法有效,能够准确评估末端运动与避障运动的优先级,相关研究工作为连续体机械臂的设计和运动控制提供了新的参考和思路.

关键词：连续体机械臂解耦避障主从任务转换

Mercury contamination and accumulation in sediments of the East China Sea

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Journal of Environmental Sciences 2010年第8期22卷 1164-1170页

作者： Tien-hsi Fang Department of Marine Environmental Informatics "National" Taiwan Ocean University

Mercury （Hg） concentrations in sediment samples collected from the inner and middle shelves of the East China Sea （ECS） were analyzed to evaluate Hg contamination levels and to calculate Hg sedimentation rates and total accumulation in the ECS. The range of Hg concentrations in surface sediments of the inner shelf was 26.5–47.6 ng/g, and that for the middle shelf was 4.1–13.9 ng/g. Hg concentrations correlated well with organic carbon contents but varied inversely with sediment grain size. Enrichment factors indicated that the whole inner shelf and a small portion of the middle shelf were slightly contaminated by Hg. Hg accumulation rates in the ECS ranged between 0.42–48.7 ng/（cm2·yr）, with higher values observed in the inner shelf. Total Hg accumulation in the calculated area （accounting for 80% of the ECS continental shelf area） ranged from 25 to 30 tons/yr; approximately 51% and 17% of the accumulated Hg mass was deposited in the Yangtze estuarine zone and the inner shelf, respectively.

关键词： Hg contamination enrichment factor accumulation the East China Sea