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Distinct MLT asymmetry of auroral kilometric radiation observed by the FAST satellite

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Earth and Planetary Physics 2025年第1期9卷 188-193页

作者： JiaWen Tang Sai Zhang Fuliang Xiao HongMing Yang Si liu YiHua He Chang Yang YuYue Jin ZhouKun Deng ping li Archie James Johnston School of Physics and Electronic Sciences Changsha University of Science and TechnologyChangsha 410114China Hunan Province Higher Education Key Laboratory of Modeling and Monitoring on the Near-Earth Electromagnetic Environments Changsha University of Science and TechnologyChangsha 410114China School of Electrical and Information Engineering Changsha University of Science and TechnologyChangsha 410114China

Auroral Kilometric Radiation (AKR) is a common radio emission,which can contribute to the magnetosphere-ionosphereatmosphere co u *** emissions have been observed in all magnetic planet magnetospheres of the solar *** this study,using observations from the FAST satellite from 30 August 1996 to 9 September 2001,the distribution of AKR in altitude=500-4500 km and invariant latitude (|ILAT|)=60°-80°has been analyzed.63045 AKR samples have been identified with~48%(52%) samples on the dayside (nightside).Of considerable interest,there is a distinct MLT asymmetry with the high occurrence rate in MLT=05-08 and 18-22(02-05 and 12-17) in the northern (southern) *** distinct MLT asymmetry is associated with the direction of Bxof the interplaneta ry magnetic *** addition,the occurrence rate on the nightside clearly increases as the AE^(*) index *** study further enriches the information and understanding of AKR in the magnetosphere as well as other similar radio emissions.

关键词： asymmetry auroral kilometric radiation interplanetary magnetic field

Relations Between Stabilities and Structures of Closo Borane Dianions

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Chinese Journal of Structural Chemistry 2006年第6期25卷 724-734页

作者： li ping Department of Chemistry College of Chemistryof Sichuan University Chengdu 610064 China

An effective method to investigate the stabilities of a series of new closo-BnHn2- （n = 12, 14, 16, 18, 20, 22, 24, 30） was put forward with the aid of G96PW91/SHC calculations. Stabilities are related to the relative stabilized energies （RSE） and the 2e3c bound geometries of closo-BnHn2-. The structures in which a boron atom connects to four atoms up to seven are stable and appear in many borides because of the lower relative stabilized energy. In geometries, both triangular and quadrangular faces are in favor of forming the structures of closo-BnHn2-. The energies of optimized geometries support the existence of these new compounds. By employing both RSE and AE per boron atom in cage, the stabilities were studied to predict the probabilities of unknown clusters in existence. The electron-deficient clusters can be understood that the positive holes should be disperse to every triangular face and lead to share the holes, wherever there are not enough electrons to occupy them. The negative charges which anions carry distribute to 2e3c bonds to increase the stabilities.

关键词： closo-BnHn^2- relative stabilized energy geometry electronic structure

Improved Information Set Decoding Algorithms over Galois Ring in the Lee Metric

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Journal of Systems Science & Complexity 2023年第3期36卷 1319-1335页

作者： li Yu WANG li-ping State Key Laboratory of Information Security Institute of Information EngineeringChinese Academy of SciencesBeijing 100093China School of Cyber Security University of Chinese Academy of SciencesBeijing 100049China

The security of most code-based cryptosystems relies on the hardness of the syndrome decoding(SD) *** best solvers of the SD problem are known as information set,decoding(ISD) ***,Weger,et al.(2020) described Stern’s ISD algorithm,s-blocks algorithm and partial Gaussian elimination algorithms in the Lee metric over an integer residue ring Z_(pm),where p is a prime number and m is a positive integer,and analyzed the time *** this paper,the authors apply a binary ISD algorithm in the Hamming metric proposed by May,et al.(2011)to solve the SD problem over the Galois ring GR(p^(m),k) endowed with the Lee metric and provide a detailed complexity *** with Stern’s algorithm over Zpmin the Lee metric,the proposed algorithm has a significant improvement in the time complexity.

关键词： Galois ring information set decoding lee metric syndrome decoding

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General Lyapunov Stability and Its Application to Time-Varying Convex Optimization

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IEEE/CAA Journal of Automatica Sinica 2024年第11期11卷 2316-2326页

作者： Zhibao Song ping li the College of Mathematics and Systems Science Shandong University of Science and Technology

In this article, a general Lyapunov stability theory of nonlinear systems is put forward and it contains asymptotic/finite-time/fast finite-time/fixed-time stability. Especially, a more accurate estimate of the settling-time function is exhibited for fixedtime stability, and it is still extraneous to the initial *** can be applied to obtain less conservative convergence time of the practical systems without the information of the initial conditions. As an application, the given fixed-time stability theorem is used to resolve time-varying(TV) convex optimization *** the Newton's method, two classes of new dynamical systems are constructed to guarantee that the solution of the dynamic system can track to the optimal trajectory of the unconstrained and equality constrained TV convex optimization problems in fixed time, respectively. Without the exact knowledge of the time derivative of the cost function gradient, a fixed-time dynamical non-smooth system is established to overcome the issue of robust TV convex optimization. Two examples are provided to illustrate the effectiveness of the proposed TV convex optimization algorithms. Subsequently, the fixed-time stability theory is extended to the theories of predefined-time/practical predefined-time stability whose bound of convergence time can be arbitrarily given in advance, without tuning the system parameters. Under which, TV convex optimization problem is solved. The previous two examples are used to demonstrate the validity of the predefined-time TV convex optimization algorithms.

关键词： Fixed-time stability nonlinear system predefined-time stability time-varying(TV)convex optimization

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Structures,stabilities,and IR and ^(13)C-NMR spectra of dihedral fullerenes:A density functional theory study

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Science China Chemistry 2012年第9期55卷 1856-1871页

作者： li ping College of Chemistry Sichuan UniversityChengdu 610064China

Dihedral fullerenes are thermodynamically stable molecules with Dnd or Dnh symmetry. Based on experimental findings, two series of dihedral fullerenes with five-fold （C5） and six-fold （C6） symmetry have been studied using density functional theory （DFT）. The DFT calculations showed that for both series the stabilities increased with increasing fullerene size. Structural analyses indicated that the stabilities are related to specific local geometries. In the case of the more abundant C5 series, the presence of approximately planar pentagons and hexagons on the top bowl favors their formation. That is to say, those fuller- enes with small dihedral angles within the polygons are readily formed, because planar hexagons lead to strengthened conjuga- tion which lowers average bonding energies （ABE） and increases thermodynamic stabilities. Non-planar hexagons at equatorial positions in tube-shaped fullerenes have an adverse effect on the conjugation and inhibit their formation. Calculations also demonstrated that fullerenes in the two series, including C50（D5h）, C60（O6h）, C80（O5d）, C96（D6d）, Cllo（D5h）, and Cl20（D5d）, have thermodynamically stable triplet structures with strong conjugation. The calculated IR and 13C NMR spectra of the fullerenes show some similarities and regular trends due to their homogenous structures. The electronic structures indicate that short dou- ble bonds in hexagons with high electron occupancies are readily attacked by electrophilic agents and can also be coordinated by transition metals. Mechanistic discussions suggested that C2 additions and C2 losses constitute reversible processes at high temperature and C2 additions in pentagonal fusions are crucial to the kinetics of the curvature of structures. C3 additions lead to the formation of large fullerenes of other types.

关键词： dihedral fullerene singlet and triplet structures IR and NMR spectra conjugate structure stability

DFT Predictions on Structures and Stabilities of Eleven-vertex nido- and closo-Heteroboranes

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Chemical Research in Chinese Universities 2009年第2期25卷 247-256页

作者： li ping College of Chemistry Sichuan University Chengdu 610064 P. R. China

Based on the octadecahedron of eleven-vertex closo-borane, the eleven-vertex closo-heteroborane was suggested with nonmetallic atoms instead of the different nonequivalent boron, and the stabilities were predicted at G96PW91/6-31＋G（3d,2p） level. The small heteroatoms, C, N, O, preferentially occupy vertex 2 with the absolutely lowest relative energy to form the high stabilization closo-heteroboranes. They cap four-membered rings to satisfy the geometrical demand of short B--Z bonds. The electron attractions from the vicinal boron atoms make the frameworks shrink. Differently, Si and Ge preferentially substitute for boron at vertex 1 with six tight B--Z bonds and form stabilized molecules. P, As, S, and Se tend to occupy vertex 4 and the optimized structures belong to the nido configura- tions. In contrast to high electronegative heteroatoms, S and Se transfer less negative charges to framework and the electropositive heteroatoms, Si and Ge transfer more negative charges to framework to form the delocalization structures. The HOMO-LUMO gaps show that most of predicted clusters possess chemical stabilities. The substitutions of heteroatoms for boron atoms in eleven-vertex closo-heteroboranes are consistent with the topological charge stabilization rule proposed by Gimarc.

关键词： Eleven-vertex closo-heteroborane Isomeric structure Stability Density functional theory(,DFT) prediction

Circle Action with Prescribed Number of Fixed Points

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Acta Mathematica Sinica,English Series 2015年第6期31卷 1035-1042页

作者： ping li Department of Mathematics Tongji University

Given any two positive integers k and n, this paper is concerned with the existence of a circle action on a closed, smooth orientable n-dimensional manifold with precisely k isolated fixed points. We first show that this existence problem can be reduced to that of an n-dimensional manifold with exactly three fixed points. Then by using a rigidity result, we determine possible weights on these three fixed points when n = 4.

关键词： Circle action fixed point weight

Theoretical Studies on Structures, Stabilities, NMR Spectra and Designing Methods of Dihedral Fullerenes of C3 Series

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Chemical Research in Chinese Universities 2014年第6期30卷 1032-1043页

作者： li ping College of Chemistry Sichuan University Chengdu 610064 P. R. China

Using bowl shaped carbon intermediates to construct dihedral fullerenes is an advisable method. Assu- ming that cap shaped C21 extends the size through building pentagons and hexagons at the U and V clefts of the brims, a series of homologous carbon intermediates was generated, in which most of the members have been unknown up to now. The joins between these homologous intermediates gave the C3 dihedral series under the restriction of C3 sym- metrical axis. The investigations point out that the stabilities of these fullerenes not only relate to the shapes of cages and the co-planarities of polygons, but also associate with the equalizations of bond lengths and the pentagonal dis- tributions. The stabilities reveal that the pentagonal distribution in cages is not negligible to the Jr delocalization, be- sides the co-planarities of hexagons and pentagons. Analyzing the possible Stone-Wales（SW） rearrangements in those fullerenes with dehydrogenated pyracyclene units（DPUs） can help us to find out the highly stable isomers. Based on the geometrical optimizations, the calculations provided the theoretical chemical shifts of unknown fullerenes and the data reconfirmed the existence of members C78 and C84. The symmetry adaptation analyses for the frontier orbitals support the formative mechanism of consecutive pentagonal and hexagonal fusions, but the simulated routes are more complicated than the pentagon road（PR） mechanism, which include not only C2 but also C3 additive reactions.

关键词： Dihedral fullerene Curvature Distortion Pentagon and hexagon Chemical shift Stone-Wales(SW) ar-rangement Density functional theory

Low complexity DOA estimation for massive UCA with single snapshot

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Journal of Systems Engineering and Electronics 2022年第1期33卷 22-27页

作者： li ping li Jianfeng ZHAO Gaofeng College of Electronic and Information Engineering Nanjing University of Aeronautics and AstronauticsNanjing 211106China

In this paper, a low complexity direction of arrival(DOA) estimation method for massive uniform circular array(UCA) with single snapshot is ***, the coarse DOAs are estimated by finding the peaks from the circular convolution between a fixed coefficient vector and the received data ***, in order to refine coarse DOA estimates, we reconstruct the direction matrix based on the coarse DOA estimations and take the first order Taylor expansion with DOA estimation offsets into ***, the refined estimations are obtained by compensating the offsets, which are obtained via least squares(LS) without any complex *** addition, the refinement can be iteratively implemented to enhance the estimation *** to the offset search method, the proposed method achieves a better estimation performance while requiring lower *** simulations are presented to demonstrate the effectiveness of the proposed method.

关键词： direction of arrival(DOA)estimation massive uniform circular array Taylor expansion low complexity