Relativistic Consistent Angular-Momentum Projected Shell-Model：Angular-Momentum Projection

The angular-momentum projection part of RECAPS is presented.Application of RECAPS to some deformed nuclei is also presented.

Relativistic Consistent Angular-Momentum Projected Shell-Model： Relativistic Mean Field

We develop a relativistic nuclear structure model, relativistic consistent angular-momentum projected shell-model (RECAPS), which combines the relativistic mean-field theory with the angular-momentum projection method. In this new model, nuclear ground-state properties are first calculated consistently using relativistic mean-field (RMF) theory. Then angular momentum projection method is used to project out states with good angular momentum from a few important configurations. By diagonalizing the hamiltonian, the energy levels and wave functions are obtained. This model is a new attempt for the understanding of nuclear structure of normal nuclei and for the prediction of nuclear properties of nuclei far from stability. In this paper, we will describe the treatment of the relativistic mean field. A computer code, RECAPS-RMF, is developed. It solves the relativistic mean field with axial-symmetric deformation in the spherical harmonic oscillator basis. Comparisons between our calculations and existing relativistic mean-field calculations are made to test the model. These include the ground-state properties of spherical nuclei 16O and 208Pb, the deformed nucleus 20Ne. Good agreement is obtained.

Shell-model representations of the microscopic version of the Bohr-Mottelson collective model

The structure of the irreducible collective spaces of the group Sp(12,R),which many-particle nuclear states are classified according to the chain Sp(12,R)⊃U(6)⊃SO(6)⊃SU_(pn)(3)⊗SO(2)⊃SO(3)of the proton-neutron symplectic model(PNSM),is considered in detail.This chain of the PNSM was recently shown to correspond to a microscopic shell-model version of the Bohr-Mottelson collective model.The construction of the relevant shell-model representations of the Sp(12,R)group along this chain is considered for three nuclei with varying collective properties and from different mass regions.It is shown that the SU_(pn)(3)basis states of the Sp(12,R)representations belonging to the SO(6)irreps with seniorityυ≥υ0,withυ0 denoting the maximal seniority SO(6)irrep contained in the Sp(12,R)bandhead,are always Pauli allowed,but organized in a different way into different SO(6)shells.This is in contrast to the case of filling the levels of the standard three-dimensional harmonic oscillator and using the plethysm operation.Although the SU_(pn)(3)multiplets withinυ<υ0 are not all Pauli forbidden,it is safe to discard them.The results obtained in the present work are important for the practical application of the microscopic version of the Bohr-Mottelson collective model.

Microscopic shell-model description of irrotational-flow dynamics in^(102)Pd

The structure of the low-lying collective excitations in 102Pd is examined within the recently proposed microscopic shell-model version of the Bohr-Mottelson(BM)collective model.A good description of the excitation energies of the lowest ground,γ,andβbands,as well as the staggering function between the collective states of theγband and some other energy-dependent quantities,is obtained.The low-energy intraband and interband quadrupole dynamics is reasonably well described within the present proton-neutron sympletic based shell-model approach without the use of an effective charge and compared with the predictions of nuclear structure models.The obtained results of the present study shed light on the question of the existence of irrotational-flow type quadrupole dynamics,which lies on the ground of the original BM model of quantized vibrations and surface-wave rotations in atomic nuclei.

On the microscopic shell-model version of the Bohr-Mottelson collective model

The recently proposed microscopic shell-model version of the Bohr-Mottelson(BM) collective model is considered in more detail in the coordinate representation.The latter possesses a clear and transparent physical meaning,which reveals several features of the new version of the collective model missed in the previous formulation.The relationship to the original BM model is considered,along with the relationships between the different limiting submodels of the microscopic version of the BM model,which closely resemble the relationships of the original Wilets-Jean and rotor models.The kinematically correct many-particle wave functions of the microscopic version of the BM model,conserving the experimentally observed integrals of motion,are shown to consist of collective irrotational-flow and intrinsic components-in accordance with the original BM unified model.The general BM Hamiltonian is obtained as a contraction limit of the microscopic many-particle nuclear Hamiltonian,or,alternatively,by restricting the latter to the scalar O(m) irreducible collective space.

用于轮胎振动分析的壳模型优化研究

虽然现有壳模型在0~500 Hz频带内精度高,适合用于轮胎结构振动分析,但由于模型中耦合了胎侧二维壳模型,导致胎冠振动模态难以分离,且模型自由度和所需输入参数增加。本文对该壳模型进行改进:在保持胎冠壳模型不变的基础上,应用轮胎环模型和板模型中对胎侧的近似方法,采用弹性基底代替胎侧二维壳模型,简化了原模型的边界条件并缩减了输入参数个数;针对改进后的壳模型建立了求解方法,实现了胎冠模态频率和振型的求解。并通过与实验数据的对比,验证了改进后的壳模型及其求解方法的正确性。

基于SHELL模型的航空货物运输安全问题研究

文章阐述了SHELL 模型的基本理论,分析了航空货物运输的基本流程及常见安全问题,应用SHELL模型重点探究航空货物运输中人与硬件(L-H)、人与软件(L-S)、人与环境(L-E)及人与人(L-L)的要素特征与关系界面,梳理引发安全问题导致不安全事件的原因,提出缩小关系界面空隙、提高关系匹配度的措施,保障航空货物运输安全,促进航空货运持续稳定发展。

基于邻域K-shell分布的关键节点识别方法

复杂网络中关键节点的精准识别对于网络结构稳定和信息传播起着至关重要的作用。传统K-shell方法仅通过节点在网络中所处位置对节点的重要性进行评估,导致区分度不高。基于此,综合考虑了节点的全局信息和局部信息对节点重要性的影响,提出一种基于邻域K-shell分布的关键节点识别方法。该方法通过节点邻域Ks值定义节点的熵,从而反映邻居节点的K-shell分布特征。通过11个网络数据集上的仿真实验,验证了所提方法能够更准确地识别并区分复杂网络中的关键节点。

基于遗传算法的斜拉桥基准模型参数修正方法

健康监测对于斜拉桥结构全寿命的安全使用十分重要,而使用传感器采集斜拉桥数据进行健康监测存在盲区.结合Benchmark模型对桥梁结构进行监测,能够在给定状态下,比较和评价不同的健康监测方法标准,对桥梁的设计、运营以及管养等方面有重要意义.本文基于背景工程,提出用于斜拉桥结构健康监测的基准模型.首先,使用Matlab建立斜拉桥的鱼骨梁简化有限元模型,并建立斜拉桥的板壳单元精细模型,作为简化补充模型和模态矫正模型;其次,采用正交试验设计,对建模过程中的待修正参数进行斜拉桥动力特性参数的显著性分析;最后,基于遗传算法对模型参数进行修正,提出了动态自适应技术和并列选择的方法优化遗传算法结构,干涉遗传选择过程,并赋予初始种群更高的离散性,与调用GA函数的方法对模型进行修正进行比较,验证了改进后的遗传算法具有更高的计算效率,模态参数误差较小.

无人机外壳逆向造型设计

为确保无人机有良好的气动布局和飞行稳定性,其外壳曲面均采用非规则曲面,逆向造型难度大,存在定位坐标系难确定、曲面造型质量难保证、曲面间连接效果不平滑等问题。通过三维扫描仪采集无人机外壳表面数据,形成STL模型;运用Siemens NX强大的曲面造型功能在无人机外壳STL模型的基础上进行逆向造型设计,获得了可编辑、可加工的三维模型文件;借助第三方检测软件Geomagic Control将逆向结果与原始标准模型对比验证逆向造型的精准性。Geomagic Control逆向造型结果表明所描述的曲面逆向造型设计思路基本正确,可为复杂曲面类零件的逆向造型提供可复制的经验。

功能梯度石墨烯增强自旋圆柱壳的振动特性

目的为了研究旋转状态下功能梯度石墨烯增强复合材料(FG-GPLRC)圆柱壳的振动特性,方法基于改进的Halpin-Tsai微观力学模型与复合材料夹杂理论预测多种分布模式下石墨烯增强结构的等效材料属性。同时,考虑由旋转引起的科氏力与离心力作用,采用一阶剪切变形理论对FG-GPLRC自旋圆柱壳的能量表达式进行推导。之后,选取切比雪夫多项式构造位移容许函数,基于Rayleigh-Ritz法对FG-GPLRC自旋圆柱壳的行波振动特性进行分析,得到壳体的动力学微分方程进而求解出行波振动频率。最后,通过与现有文献数据进行对比,验证本文方法的准确性,并分析分层数、转速、石墨烯片的质量分数与分布模式等因素对旋转壳体振动特性的影响。结果石墨烯片分层数为10层时,即可实现对FG-GPLRC自旋圆柱壳振动特性的预测;石墨烯质量分数小于2%时,每增加0.5%,壳体的前后行波频率明显提高;在不同模态下,GPL-X分布模式的壳体行波频率最高,GPL-O分布模式最低,且行波频率随转速的提高而增大;弹性边界条件下,壳体行波振动频率随轴向半波数的增大而增加。结论石墨烯片在GPL-X分布模式下使得FG-GPLRC自旋圆柱壳的等效弹性模量增大,对壳体结构刚度的增强效果最佳,且前后行波频率与壳体转速同步增大。

基于文本分析的飞机牵引车作业不安全事件研究

为了研究飞机牵引车作业过程的安全性,文章对1989年至2023年间自愿报告系统(ASRS)中12537条涉及飞机牵引车作业不安全事件的叙述和简述部分进行了文本挖掘和文本分析,并结合SHELL模型识别了飞机牵引车作业关键要素,最后采用SHEL-Jaccard系数矩阵对关键要素之间的关系进行分析,提出飞机牵引车作业安全预防和控制措施。研究发现,飞机牵引车作业关键要素如下:以销、刹车、速度控制装置、连接装置、通讯设备为主的硬件要素;以牵引车检查单、机场地面引导线、机场管理为主的软件要素;以牵引车司机、引导、警戒和机组为主的主要人员和以能见度、地面状况、障碍物为主的环境要素。

大跨度木结构蒙古包的设计与工程实践

在我国“双碳”目标的实现和新时代中国民族建筑复兴的背景下,木结构建筑市场再次兴起。在原民族建筑文化内涵的基础上对结构进行创新,以满足现代市场的需求已成为新的研究方向。本文针对希拉穆仁草原景区设计了一座大跨度蒙古包,在不改变建筑材料的基础上,采用木网壳结构体系对传统建筑结构进行创新与优化,其最大跨度为23.5 m,最大高度为11.5 m,且整体结构稳定。在此基础上,利用有限元软件进行建模,对可能出现的各种工况进行静力计算和屈曲分析,验证了该结构的可靠性。本研究对我国大跨度木结构的发展和传统木结构建筑的创新具有重要的借鉴意义。

花生RIL群体出仁率的遗传特性分析

出仁率是花生的产量性状之一,是籽仁产量的重要影响因子。本研究以花育44×DF12构建的重组自交系(RIL)群体为试验材料,出仁率作为表型数据,利用主基因+多基因混合遗传模型对3个环境下的出仁率进行遗传特性分析。结果表明,3个环境下的出仁率的最适遗传模型均为4MG-AI,即4对加性—上位性主基因调控,3个环境下的主基因遗传率分别为91.93%,90.60%,96.85%。本研究结果为出仁率遗传机制挖掘奠定了重要理论依据。

基于GPU加速的投影后变分壳模型计算

为进一步拓展投影后变分(VAP)壳模型计算应用核区范围,需提升VAP的计算效率。为此,利用OpenACC并行编程指令,首次将VAP程序从传统的CPU平台移植到了高性能GPU计算平台上。在角动量投影的每个积分格点上实现了数目庞大的各独立转动矩阵元的GPU并行化计算。经验证,采用GPU加速后的VAP程序计算得到的结果与原来的OpenMP并行化程序计算得到的结果完全相同,而计算效率得到了数倍的提升。借助于GPU加速技术,首次计算了变形重核^(178)Hf的基带能谱,打开了VAP壳模型方法应用于变形稀土重核之门。

地铁车站矩形顶管壳-接头理论模型及纵向变形

针对矩形顶管隧道易受影响产生纵向变形、进而引发接头破坏的问题,提出一种矩形顶管隧道壳-接头理论模型,并以此研究隧道在不均匀沉降作用下的纵向变形。首先,通过室内模型试验,探究矩形顶管隧道接头力学特性;其次,建立壳-接头理论模型,给出接头力学元件的刚度矩阵及其计算方法;然后,建立数值模型,并与室内模型试验结果进行对比;最后,依托20环管节的矩形顶管隧道工程实例,研究不均匀沉降作用下的隧道纵向变形。结果表明:接头破坏表现为闭合间隙、钢套环受力和变形破坏3个阶段,接头的抗剪和抗弯均由钢套环承担;壳-接头理论模型的模拟计算结果与模型试验结果较吻合,验证了模型的实用性和准确性;矩形顶管隧道的纵向变形受地基刚度影响显著,砾砂、粉砂和黏土3种地层对应的隧道最大附加沉降分别为3.72,7.66和12.14 mm,随着地基刚度的减小,隧道接头受不均匀沉降的影响将会增大。

K6型单层球面网壳整体交互耦合屈曲行为

采用有限元数值模拟,基于K6型单层球面网壳的屈曲与后屈曲性态,提出整体屈曲的判别准则,并首次从变形特征角度分析两种整体屈曲模态交互耦合的发生机理及对屈曲承载力的削弱效应。研究结果表明,K6型单层球面网壳的稳定性易受整体交互耦合屈曲影响,且可导致屈曲极限承载力的显著削弱及不稳定后屈曲;其变形模式从屈曲阶段的最低阶整体屈曲模态主导,演化为初始后屈曲阶段的整体交互耦合屈曲模态主导,及最终的次低阶整体屈曲模态主导,是交互耦合屈曲产生的原因;缺陷幅值也会影响整体交互耦合屈曲对K6型单层球面网壳屈曲极限性能的主导作用。

锰改性核桃壳基生物炭去除水中刚果红的研究

以农业废弃物核桃壳作为原材料,通过炭化与共沉淀法两步制备锰改性生物炭,用于去除水中典型的阴离子染料刚果红。研究刚果红不同初始浓度、接触时间、生物炭投加量、溶液pH对刚果红去除效果的影响。结果表明,在pH为3,刚果红初始浓度为10 mg/L,生物炭投加量为10 mg,振荡时间60 min时,锰改性核桃壳对水中刚果红的去除率可达97.31%,与未改性的核桃壳相比,去除率提高至1.51倍。结合傅里叶红外光谱(FT-IR)与X射线衍射分析(XRD)对生物炭的结构变化以及吸附特征进行分析,通过动力学模型与热力学模型拟合,表明该吸附过程主要受化学吸附影响,该吸附为自发且不可逆的吸热反应。

Shell-model studies of the N=14 and 16 shell closures in neutron-rich nuclei

Shell-model studies on the N =14 and 16 shell closures in neutron-rich Be, C, O and Ne isotopes are presented. We calculate, with the WBT interaction, the excited states in these nuclei. The calculations agree with recent experiment data. Excited energies and B(E2) values are displayed to discuss the shell closures. Our results support the N =16 shell closure in these isotopes, while indicating a disappearance of N =14 shell closure in Be and C isotopes.

α-cluster structure of ^(12)C and ^(16)O in the covariant density functional theory with a shell-model-like approach

The α-cluster structures for 12^C and 16^O are investigated in the framework of the covariant density functional theory, where the pairing correlation is treated with a particle number conserving shell-model-like approach. The ground states of 12^C and 160 have been calculated and the density distributions demonstrate an equilateral triangle 3α clustering for 12^C and a regular tetrahedron 4α clustering for 16^O The existence of linear nα chain structure of both 12^C and 16^O is revealed at high quadrupole deformation.