With the development of radioactive-ion-beam facilities,many exotic phenomena have been discovered or predicted in the nuclei far from the stability line,including cluster structure,shell structure,deformed halo,and shape decoupling effects.The study of exotic nuclear phenomena is at the frontier of nuclear physics nowadays.The covariant density functional theory(CDFT)is one of the most successful microscopic models in describing the structure of nuclei in almost the whole nuclear chart.Within the framework of CDFT,toward a proper treatment of deformation and weak binding,the deformed relativistic Hartree-Bogoliubov theory in continuum(DRHBc)has been developed.In this contribution,we review the applications and extensions of the DRHBc theory to the study of exotic nuclei.The DRHBc theory has been used to investigate the deformed halos in B,C,Ne,Na,and Mg isotopes and the theoretical descriptions are reasonably consistent with available data.A DRHBc Mass Table Collaboration has been founded,aiming at a high precision nuclear mass table with deformation and continuum effects included,which is underway.By implementing the angular momentum projection based on the DRHBc theory,the rotational excitations of deformed halos have been investigated and it is shown that the deformed halos and shape decoupling effects also exist in the low-lying rotational excitation states of deformed halo nuclei.
In this study, the effect of extreme laser fields on the α decay process of ground-state even–even nuclei was investigated.Using the deformed Gamow-like model, we found that state-of-the-art lasers can cause a slight change in the α decay penetration probability of most nuclei. In addition, we studied the correlation between the rate of change of the α decay penetration probability and angle between the directions of the laser electric field and α particle emission for different nuclei. Based on this correlation, the average effect of extreme laser fields on the half-life of many nuclei with arbitrary α particle emission angles was calculated. The calculations show that the laser suppression and promotion effects on the α decay penetration probability of the nuclei population with completely random α particle-emission directions are not completely canceled.The remainder led to a change in the average penetration probability of the nuclei. Furthermore, the possibility of achieving a higher average rate of change by altering the spatial shape of the laser is explored. We conclude that circularly polarized lasers may be helpful in future experiments to achieve a more significant average rate of change of the α decay half-life of the nuclei population.
In this study,proton emission half-lives were investigated for deformed proton emitters with 53≤Z≤83based on the presented deformed Gamow-like model,where the deformation effect was included in the Coulomb potential.The experimental half-lives of proton emitters can be reproduced within a factor of 3.45.For comparison,the results from the universal decay law and the new Geiger-Nuttall law are also presented.Furthermore,the relevance of the half-lives to the angular momentum l for ^(117)La,^(121)Pr,^(135)Tb,and ^(141)Ho were analyzed,and the corresponding possible values of l were proposed:l=3,3,4,4.
The widely spread Carboniferous-Permian coal seam group in southern China has great potential for coalbed methane resources,but the extensively developed tectonically deformed coal seriously restricts its development.Taking the Dahebian block in western Guizhou as the study area,the geological model of coalbed methane reservoirs in the tectonically deformed coal seam group was established,and the spatial distribution pattern of model parameters was clarified by clustering algorithms and factor analysis.The facies model suggests that the main coal body structures in Nos.1,4,and 7 coal seams are cataclastic coal and granulated coal,whereas the No.11 coal seam is dominated by granulated coal,which has larger thicknesses and spreads more continuously.The in situ permeability of primary undeformed coal,cataclastic coal,granulated coal,and mylonitized coal reservoirs are 0.333 mD,0.931 mD,0.146 mD,and 0.099 mD,respectively,according to the production performance analysis method.The property model constructed by facies-controlled modeling reveals that Nos.1,4,and 7 coal seams have a wider high-permeability area,but the gas content is lower;the high-permeability area in the No.11 coal seam is more limited,but the gas content is higher.The results of the self-organizing map neural network and K-means clustering indicate that the geological model can be divided into 6 clusters,the model parameter characteristics of the 6 clusters are summarized by data analysis in combination with 6 factors extracted by factor analysis,and the application of data analysis results in multi-layer coalbed methane co-development is presented.This study provides ideas for the geological modeling in the tectonically deformed coal seam group and its data analysis.
It is still a challenge to simultaneously enhance coercivity(H_(cj))and remanence(J_(r))of hot-deformed Nd-Fe-B magnet due to the coercivity-remanence trade-off dilemma.Here,we achieved this balance between H_(cj)and Jr by flake Cu powder assisted DyF_(3)interflake addition.The Hcj increases from 1218 to 1496 kA/m and Jr increases from 1.32 to 1.34 T compared with the original magnet.Results show that the width of coarse grain layers reduces because of the introduction of flake Cu,which increases the contact areas of the adjacent grains at ribbon interfaces and suppresses the excessive growth of grains.The stronger degree of texture and higher density compared with the original magnet should take the responsibility for the increase of J_(r).Additionally,the aggregation regions of rare earth rich(RE-rich)phase reduce and the betterment of the microstructure is another reason for the enhancement of Jr in the flake Cu aided DyF_(3)hot-deformed magnet.This strategy of using flake powder additives provides a promising method for optimizing microstructure and enhancing magnetic properties of hot-deformed Nd-Fe-B magnets.
Yikuan HuJiajie LiShengyu SunShuwei ZhongMunan YangXiaoqiang YuSajjad Ur RehmanXi Yu
Aiming at the lack of suitable machines for sweet potato seedling transplanting in China,and according to the agronomic requirements for the horizontal insertion method of sweet potato seedling,a new sweet potato seedling transplanting mechanism of planetary gear train was proposed based on the non-uniform transmission of deformed elliptical gear.The working principle of the transplanting mechanism was analyzed,and the kinematics modeling and analysis of the mechanism were carried out.The study established the numerical objectives of the transplanting mechanism and applied the theory of membership function to establish a mathematical model for the parameter-guided optimization design of the transplanting mechanism.The parameter-guided optimization design software was developed to obtain a set of optimal mechanism parameters that satisfied the motion trajectory of sweet potato transplanting and the posture of the transplanting arm.Based on the optimized parameters,the structure of the transplanting mechanism was designed,and a virtual prototype of the mechanism was created,whereby a virtual motion simulation of the transplanting mechanism was conducted to verify the correctness of the kinematics model and design of the mechanism.The high-speed photographic kinematics test of the mechanism prototype and sweet potato seedling transplanting tests were conducted to test the mechanism’s kinematic characteristics and transplanting performance.The test results show that the test trajectory of the mechanism and test posture of the transplanting arm are almost consistent with the theoretical and simulation trajectory,meeting the agronomic requirements of the horizontal insertion method of sweet potato seedling;And when the rotary speed of the mechanism are 20 r/min and 30 r/min,the average success ratios of sweet potato seedlings transplanting are 90%and 82%,respectively,which prove the application feasibility of the mechanism in the practical machines.
Bingliang YeYuxuan YeHaili ZhouGaohong YuXiong ZhaoBin Deng
The exploration of spin symmetry (SS) in nuclear physics has been instrumental in identifying atomic nucleus structures.In this study,we solve the Dirac equation from the relativistic mean field (RMF) in complex momentum representation.We investigated SS and its breaking in single-particle resonant states within deformed nuclei,with a focus on the illustrative nucleus168Er.This was the initial discovery of a resonant spin doublet in a deformed nucleus,with the expectation of the SS approaching the continuum threshold.With increasing single-particle energy,the splitting of the resonant spin doublets widened significantly.This escalating splitting implies diminishing adherence to the SS,indicating a departure from the expected behavior as the energy levels increase.We also analyzed the width of the resonant states,showing that lower orbital angular momentum resonances possess shorter decay times and that SS is preserved within broad resonant doublets,as opposed to narrow resonant doublets.Comparing the radial density of the upper components for the bound-state and resonant-state doublets,it becomes evident that while SS is well-preserved in the bound states,it deteriorates in the resonant states.The impact of nuclear deformation (β_(2)) on SS was examined,demonstrating that an increase in β_(2) resulted in higher energy and width splitting in the resonant spin doublets,which is attributed to increased component mixing.Furthermore,the sensitivity of spin doublets to various potential parameters such as surface diffuseness (a),radius (R),and depth (Σ0) is discussed,emphasizing the role of these parameters in SS.This study provides valuable insights into the behavior of spin doublets in deformed nuclei and their interplay with the nuclear structure,thereby advancing our understanding of SS in the resonance state.