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在Brueckner-Hartree-Fock理论框架内, 研究了同位旋非对称核物质中质子和中子单粒子势的动量相关性及其随同位旋非对称度的变化, 在此基础上计算了同位旋对称势, 并讨论了三体核力的影响. 结果表明同位旋对称势对于同位旋非对称度的依赖性很弱, 但对于动量和密度均有较强的依赖性. 当密度固定时, 同位旋对称势随动量增加而减小. 尽管三体核力对于质子和中子单粒子势的动量相关性有较大影响, 但对同位旋对称势的影响很小. 还与目前重离子碰撞输运理论模型中所使用的各种参数化的唯象对称势进行了比较. 相似文献
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综合分析规范空间的中子数和费米面(N~λ_n)关系,位能面及壳修正能量的结果表明,_(36)Kr同位素出现形状共存的区域是一个N窗,N≈38~42。 相似文献
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利用3个具有不同的同位旋和动量相关性的热力学模型研究了非对称核物质的热力学性质, 它们是重离子碰撞中同位旋弥散数据约束下的、 同位旋和动量相关的MDI模型, 完全动量无关的MID模型, 以及同位旋标量动量相关的extended MDYI(eMDYI)模型。 主要研究了同位旋非对称热核物质的对称能和系统力、 化学不稳定性以及液气相变的温度效应。 MDI模型对称能的温度效应来源于动能和势能两部分贡献, 而MID和eMDYI模型只有势能部分对对称能的温度效应有贡献。 研究结果还表明, 力学不稳定性区域、 化学不稳定性区域和液气共存区都依赖于模型的同位旋和动量相关性, 以及对称能的密度依赖关系。In this article, three models with different isospin and momentum dependence are used to study the thermodynamical properties of asymmetric nuclear matter. They are isospin and momentum dependent MDI interaction constrained by the isospin diffusion data of heavy ion collision, the momentum independent MID interaction and the isoscalar momentum dependent eMDYI interaction. Temperature effects of symmetry energy, mechanical and chemical instability and liquid gas phase transition are analyzed. It is found that for MDI model the temperature effects of the symmetry energy attribute from both the kinetic and potential energy, while only potential part contributes to the decreasing of the symmetry energy for MID and eMDYI models. We also find that the mechanical instability, chemical instability and liquid gas phase transition are all sensitive to the isospin and momentum dependence and the density dependence of the symmetry energy. 相似文献
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摘要:针对模型参数不确定、存在外界风浪流干扰的欠驱动无人水面艇的航迹跟踪问题,为提高无人水面艇自主航行能力,减小航迹跟踪过程中的轨迹偏差与跟踪迟滞,提出了一种分层控制结构的方法。由外至内采取航迹、航向、舵角三层控制,外环航迹控制层使用过渡目标点策略,根据无人水面艇的偏航距确定实时目标点,中环航向控制层使用最小转角策略,根据无人水面艇艏向角与目标方向角之差确定偏转打角,内环舵角控制层使用模糊自适应整定PID控制器,对模型参数的动态变化进行补偿。基于MATLAB GUI进行无人水面艇航迹跟踪控制仿真试验,结果表明,模糊自适应整定PID控制器提高了舵角的控制响应速度,无人水面艇在航行过程中的直线行驶、连续折线行驶均能得到较好的航迹跟踪控制。 相似文献
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利用同位旋和动量相关的相对论强子输运模型IBUU04, 以中心碰撞124Sn+124Sn(132Sn+124Sn), 112Sn+112Sn双反应系统在E/A=50MeV(400MeV)为例, 在两种不同的对称能作用下, 研究了发射粒子谱中双n/p比随时间和动能的演化.
计算双n/p比的好处是它缩弱了库仑效应与探测低能中子的低效率的影响.
计算结果表明, 无论是在高密还是低密情况下, 双n/p比的动能分布都敏感地依赖于对称能, 因此双n/p比是探测对称能的一个理想探针. 相似文献
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Using the momentum- and isospin-dependent Boltmann-Uehling-Uhlenbeck (BUU) model, we investigate the transverse flow and balance energy in two isotopic colliding systems ^48Ca+^58Fe and ^48Cr+^58Ni by adopting different symmetry potentials. By comparing the results between the two colliding systems, we find that the difference between the balance energies of two isotopic systems can be considered as a sensitive probe to the density dependence of symmetry energy. 相似文献
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同位旋物理的主要任务之一是通过放射性核束引起的核反应来探索介质中有效核子-核子相互作用的同位旋依赖性,尤其是同位旋相关的核物质状态方程, 即密度依赖的核物质对称能。由于对称能,尤其是其高密行为,对核物理学和天体物理学具有重要意义,密度依赖的对称能在过去10年一直是中能重离子物理研究领域的主要焦点之一。近年来,低密对称能的研究已经取得了重要进展, 而对称能的高密行为仍然很不确定。在理论方面,人们提出了许多对高密对称能敏感的观测量。 实验方面, 关于对称能高密行为研究的实验计划已经展开,世界各地正在建造的放射性核束装置为对称能的高密行为研究提供了新的机遇。基于IBUU输运模型综述了研究对称能高密行为的一些敏感观测量及其最新进展, 以及所面临的挑战与机遇。One of the major tasks of studying isospin physics via heavy ion collisions with neutron rich nuclei, is to explore the isospin dependence of in medium nuclear effective interactions and the equation of state of neutron rich nuclear matter, i.e., the density dependence of nuclear symmetry energy. Because of its great importance for understanding many phenomena in both nuclear physics and astrophysics, the study of the density dependence of nuclear symmetry energy has been the main focus of the intermediate energy heavy ion physics community during the last decade. Nowadays significant progress has been achieved in studying the low density behavior of nuclear symmetry energy, but the high density behavior of nuclear symmetry energy is still very uncertain. Theoretically, a number of observables have been proposed as sensitive probes to the high density behavior of nuclear symmetry energy. With new opportunities provided by the various radioactive beam facilities being constructed around the world, studies of the high density behavior of nuclear symmetry energy is expected to be one of the main forefront research areas in nuclear physics in the near future. In this report, based on the transport model IBUU we have reviewed the major progress achieved in studying the high density behavior of nuclear symmetry energy and discussed future challenges in this field. 相似文献