Er,Yb同位素链的基态形状(量子相)酷越研究(英文)

利用严格求解的Nilsson轴形变平均场加扩展对力模型,对Er和Yb同位素链基态形状（量子相）酷越进行了研究。通过该模型下能级比R_02+/21+、奇偶能差、信息熵的计算,成功地再现了155-163Er和157-165Yb同位素相关物理量的形状（量子相）酷越行为。通过分析这些量随着四极形变参数和总体对力强度的变化过程,显示了这种酷越行为主要是由于对力强度与四极形变之间的竞争导致的,该结果揭示了本模型下的基态形状（量子相）酷越行为的来源。Ground-state shape (phase) crossover in Er and Yb isotopes is manifested in the axially deformed Nilsson mean-field plus extended pairing model. The energy ratio R_02+/21+, the odd-even mass differences and the information entropy are calculated under the present model, reproduce the shape (phase) crossover behaviors of these quantities in 155-163Er and 157-165Yb isotopes. From the analysis of these quantities as functions of the quadrupole deformation parameter and the overall pairing interaction strength, it is shown that the crossover is mainly driven by the competition between the pairing interaction and the quadrupole deformation, which thus provides the origin of the shape (phase) crossover in the present model.     

Er，Yb和Hf同位素的基态占有率（英文）

应用严格求解的Nilsson 平均场加推广对力模型,在同时考虑质子-质子和中子-中子间对力相互作用的情况下,对稀土区的152-164Er,154-166Yb 和156-168Hf 核素的结合能、奇偶能差、低激发态转动惯量等基态性质进行系统的统一描述。通过计算结果与实验数值比较分析显示,对力相互作用在阐明以上核素能谱的基态性质中起到了关键的作用。应用拟合上述物理量所确定的模型参数,对156-162Yb 核素基态中价核子配成角动量J = 0,1,… ,12的价核子对占有率的计算结果显示,配成角动量为偶数价核子对的占有率远远高于配成角动量为奇数价核子对的占有率,其数值结果揭示了配成角动量为S,D和G的价核子对在所考虑的核素基态性质中占主导地位。The Nilsson mean-field plus extended-pairing model for deformed nuclei is applied to describe the ground-state properties of selected rare-earth nuclei. Binding energies, even-odd mass differences, moments of inertia for the ground-state band of 152-164Er, 154-166Yb, and 156-168Hf are calculated systematically in the model employing both proton-proton and neutron-neutron pairing interactions. In comparison with the corresponding experimental data, it is shown that for these rare-earth nuclei, pairing interaction is crucial in elucidating the properties of the ground state. With model parameters determined by fitting the energies of these states, ground-state occupation probabilities of valence nucleon pairs with angular momentum J =0,1, …,12 for even-even 156-162Yb are calculated. It is inferred that the occupation probabilities of valence nucleon pairs with even angular momenta are much higher than those of valence nucleon pairs with odd angular momenta. The results clearly indicate that S, D, and G valence nucleon pairs dominate in the ground state of these nuclei.     

基于改进支持向量机的水声目标-杂波不平衡分类研究

针对水声目标-杂波数据集在有限样本下的类不平衡特性,导致代价敏感支持向量机难以逼近贝叶斯最优决策的问题,本文提出了一种基于能量统计(Energy statistics)方法的支持向量机(En-SVM)。该算法通过度量原始数据空间与有限样本空间特征函数之间的加权平方距离,量化少数类样本不完全采样过程中的信息损失,来补偿再生核希尔伯特空间中机器学习算法所需的少数类分类信息,增加少数类样本对决策的影响力。实验结果表明,En-SVM能够在保持高检测概率的同时获得较低虚警概率,即通过分类可以排除大量的杂波,性能优于标准支持向量机和代价敏感支持向量机,能够有效处理水声不平衡数据的分类问题,实现主动声呐信号处理中的杂波抑制。     

标准对力模型的新迭代方法(英文)

建立了一种求解标准对力模型的新迭代方法。该方法基于标准对力模型的多项式方案,为球形和形变系统提供了方便的初始值预测。特别是对于大尺寸系统,该方法将求解k对多项式的系统方程式简化为分步求解1对多项式系统的迭代过程,并通过快速Newton-Raphson以及Monte Carlo采样算法逐步提供初始值预测。通过扩展,本算法还可用于解决Gaudin型量子多体问题,例如考虑超过100条轨道、50对的大尺寸系统,以及超形变核、核裂变的研究中。A new iterative approach for solving the standard pairing problem is established based on polynomial approach. It provides an efficient way to derive the particle-number conserved pairing wave functions for both spherical and deformed systems, especially for large-size systems. The method reduces the complexity of solving a system for k-pairs polynomial equations into a system for one-pair polynomial equation, which can be efficiently implemented by the Newton-Raphson algorithm with a Monte Carlo sampling procedure for providing the initial guesses step by step. The present algorithm can also be used to solve a large class of Gaudin type quantum many-body problems as a more than 100 orbitals and 50 pairs system such as super-heavy nuclei and nuclear fission.     

Nilsson mean-field plus the extended pairing model description of rare earth nuclei

The Nilsson mean-field plus the extended pairing model for well-deformed nuclei is applied to some representative rare earth examples. The binding energies, some low-lying pair-excited states and even-odd mass differences of Er, Yb and Hf isotopes are calculated systematically within the proton frozen-pair excitation limit. A comparison with experimental data for these nuclei shows that the results of the extended pairing model are better than those for the standard pairing model with the BCS approximation and the nearest-orbit pairing model.