通讯机构：
[Zhou, MH; Ren, Z ] C;Chinese Acad Sci, Beijing Natl Lab Condensed Matter Phys, Inst Phys, Beijing 100190, Peoples R China.;Univ Chinese Acad Sci, Sch Phys Sci, Beijing 100049, Peoples R China.
摘要：
We report the crystal and electronic structures, charge density wave (CDW), and superconductivity of polycrystalline 4Ha-NbSe2 studied by x-ray diffraction, ab initio calculations, electrical resistivity, magnetization, and specific heat. 4Ha-NbSe2 has no central inversion symmetry (space group P-6m2), and the stacking-fault structure was observed in the crystal lattice. The weak CDW transition at TCDW -43 K thermodynamically is of second order. 4Ha-NbSe2 has a superconducting critical temperature Tc -6.4 K, which is a moderately coupled BCS superconductor with two-gap s +s-wave-like pairing. The upper critical field mu 0Hc2(0) is as high as 26.5 T which far exceeds the Pauli paramagnetic limit and this violation is mostly attributed to the breaking of the central inversion symmetry. Second magnetization peaks can be observed in the system with weak flux pinning. Electronic structure calculations reveal that the Nb 4d orbitals dominate the bands near the Fermi level with different degree of hybridization between the Nb 4d and Se 4p orbitals in 2H- and 4Ha-NbSe2, and the band structures of 4Ha-NbSe2 favor a higher TCDW. The higher TCDW but lower Tc compared to 2H-NbSe2 leads us to conclude that the two collective electronic states are competitive on the Fermi surface in this system. The large mu 0Hc2(0) derived from 4Ha-NbSe2 is expected to stimulate the explorations for high-field superconductor applications from a noncentrosymmetric structural strategy.
摘要：
In the present work, based on Wentzel-Kramers-Brillouin theory, we systematically study the cluster
radioactivity half-lives of 22 nuclei ranging from 221Fr to 242Cm by using a phenomenological model, which considers
the screened electrostatic effect of Coulomb potential. In this model, there are two adjustable parameters i.e. the
parameter t and g, which are related to the screened electrostatic barrier and the strength of spectroscopic factor,
respectively. The calculated results indicate this model can well reproduce the experimental data while the corre sponding root-mean-square (rms) deviation is 0.660. In addition, we extend this model to predict the half-lives of
possible cluster radioactive candidates whose cluster radioactivity are energetically allowed or observed but not
yet quantified in the evaluated nuclear properties table NUBASE2020. The predicted results are consistent with
the ones obtained by using other theoretical models and/or empirical formulae including the universal decay law
(UDL) proposed by Qi et al. [Phys. Rev. C 80, 044326 (2009)], a semi-empirical model for both α decay and cluster
radioactivity proposed by Santhosh et al. [J. Phys. G 35, 085102 (2008)] and a unified formula of half-lives for α
decay and cluster radioactivity proposed by Ni et al. [Phys. Rev. C 78, 044310 (2008)].
摘要：
In the present work, the cluster radioactivity preformation probability Pc in the scheme of NpNn for the effective number of the valence particles (holes) in trans-lead nuclei has been systematically investigated. This quantity has been explored in the simplified parametrization of NpNn as well as the multiplication NpNnI of this product with the isospin asymmetry I. The calculations for Pc are both performed in microscopic and model-dependent way. Within the microscopic approach, based on our previous work [Chin. Phys. C 47, 014101 (2023)], Pc is calculated in cluster formation model combined with the exponential relationship of Pc to the & alpha; decay preformation probability P & alpha; when the mass number of the emitted cluster Ac 28. While Ac 28, Pc is obtained through the charge-number dependence of Pc on the decay products proposed by Ren et al. [Phys. Rev. C 70, 034304 (2004)]. In the model-dependent approach, Pc is extracted through the ratios from calculated cluster radioactivity half-lives in the framework of unified fission model proposed by Dong et al. [Eur. Phys. J. A 41, 197 (2009)] to experimental ones. Both of the results show Pc in logarithmic form are linear to NpNn as well as NpNnI. For comparison, the parent-mass-number dependence analytical formula as well as the model proposed by Wei and Zhang [Phys. Rev. C 96, 021601(R) (2017)] are also used. Furthermore, the preformation mechanic for cluster radioactivity has also been discussed.
摘要：
In this paper, the speed selection for the time periodic traveling wave solutions of a two-species competition lattice model of diffusive Lotka-Volterra type is investigated. By using the upper-lower solution method, an abstract result and several explicit sufficient conditions for linear selection are established. Moreover, a general condition for nonlinear selection is also obtained, which indicates that the minimal speed is nonlinearly selected if the system admits a lower solution with faster decay at the far end. Based on this result, some explicit conditions for nonlinear selection are found by constructing novel lower solutions.(c) 2022 Elsevier Inc. All rights reserved.
摘要：
The commercial exploitation of the deep-sea massive deep-sea polymetallic nodules depends on the excellent tractive performance of the deep-sea tracked miner. The walking safety and trafficability of the deep-sea tracked miner are greatly influenced by the traction of the crawler with multi track shoes. The total tractions generated from the two cases of failure surface under the uniformed pressure are deduced and analyzed based on the principle of virtual power. By substituting specified parameters, the traction weakening effect of multi track shoes is discovered, and then corresponding expression is put forward and verified by comparing the tested and theoretical traction relationships based on the traction test of multi track shoes. The research results show that the height and the distance should be considered into the design in a comprehensive way because of the existence of the weakening effect. The mechanism revealing of the source of the multi track shoe tractions could help to achieve the appropriate size of the track shoe and more traction according to the different track shoe distance.
期刊：
Journal of Scientific Computing,2023年95(1):1-23 ISSN：0885-7474
通讯作者：
Li-Lian Wang
作者机构：
[Li, Lin] Univ South China, Sch Math & Phys, Hengyang 421001, Peoples R China.;[Li, Lin] Univ South China, Hunan Key Lab Math Modeling & Sci Comp, Hengyang 421001, Peoples R China.;[Wang, Li-Lian] Nanyang Technol Univ, Sch Phys & Math Sci, Div Math Sci, Singapore 637371, Singapore.;[Li, Huiyuan] Chinese Acad Sci, Lab Parallel Comp Inst Software, State Key Lab Comp Sci, Beijing 100190, Peoples R China.
通讯机构：
[Li-Lian Wang] D;Division of Mathematical Sciences, School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore, Singapore
摘要：
It is quite common that a nonlinear partial differential equation (PDE) admits multiple distinct solutions and each solution may carry a unique physical meaning. One typical approach for finding multiple solutions is to use the Newton method with different initial guesses that ideally fall into the basins of attraction confining the solutions. In this paper, we propose a fast and accurate numerical method for multiple solutions comprised of three ingredients: (i) a well-designed spectral-Galerkin discretization of the underlying PDE leading to a nonlinear algebraic system (NLAS) with multiple solutions; (ii) an effective deflation technique to eliminate a known (founded) solution from the other unknown solutions leading to deflated NLAS; and (iii) a viable nonlinear least-squares and trust-region (LSTR) method for solving the NLAS and the deflated NLAS to find the multiple solutions sequentially one by one. We demonstrate through ample examples of differential equations and comparison with relevant existing approaches that the spectral LSTR-Deflation method has the merits: (i) it is quite flexible in choosing initial values, even starting from the same initial guess for finding all multiple solutions; (ii) it guarantees high-order accuracy; and (iii) it is quite fast to locate multiple distinct solutions and explore new solutions which are not reported in literature.
作者机构：
[Ni, Shunli; Ni, SL; Xu, Zhenghua; Zou, Zhiwei; Li, Zhifeng] Univ South China, Sch Math & Phys, Hengyang 421001, Peoples R China.;[Lin, Zefeng; Ren, Zhi-an; Zhou, Menghu; Ruan, Binbin] Chinese Acad Sci, Inst Phys, Beijing Natl Lab Condensed Matter Phys, Beijing 100190, Peoples R China.
通讯机构：
[Ni, SL ] U;Univ South China, Sch Math & Phys, Hengyang 421001, Peoples R China.
摘要：
Here, pristine and Pd-intercalated 2H-TaS2 single crystals with (00l) orientation were grown by the chemical vapor transport technique. The superconductivity (SC) and charge density wave (CDW) were characterized by magnetic and electrical transport measurements. We find that SC and CDW in the pristine 2H-TaS2 condense respectively at transition temperatures Tc - 0.8 K and TCDW -78 K. The CDW order is completely suppressed, and Tc is greatly enhanced to 4.5 K in 2H-Pd0.04TaS2, which concludes a competing relation between the two collective electronic states. The positive Hall coefficient RH for both samples above 78 K indicates that hole-type carriers dominate the transport properties, and almost the same RH reveals tiny charge transfer between the intercalant Pd and the host TaS2. The difference of RH below 78 K between TaS2 and Pd0.04TaS2 is attributed to the reconstruction of the Fermi surface by Pd-intercalation-induced collapse of the CDW order. Therefore, the prominently improved Tc in 2H-Pd0.04TaS2 is mainly caused by the change of electronic structure due to the suppression of the CDW state rather than charge injection by Pd intercalation.
摘要：
In this paper, we construct three classes of permutation quadrinomials with Niho exponents of the form
$$f(x)=\alpha _0x^r+\alpha _1x^{s_1(p^m-1)+r}+\alpha _2x^{s_2(p^m-1)+r}+\alpha _3x^{s_3(p^m-1)+r}\in \mathbb {F}_{p^{n}}[x]$$
, where p is an odd prime,
$$n=2m $$
is a positive even integer, and
$$(r,s_1,s_2,s_3)=(1,\frac{-1}{p^k-2},1,\frac{p^k-1}{p^k-2})$$
,
$$(1,\frac{p^k+1}{p^k+2},1,\frac{1}{p^k+2})$$
and (3,1,2,3), respectively. The exponents of the first two classes are considered for the first time, and the third class covers all the permutation polynomials proposed by Gupta (Designs Codes and Cryptography 88, 1–17, 2020).
作者机构：
[Zhang, Yiqing; Ling, Xueqing; Xu, Feng; Zhang, YQ] Univ South China, Sch Math & Phys, Hengyang 421001, Peoples R China.
通讯机构：
[Zhang, YQ ] U;Univ South China, Sch Math & Phys, Hengyang 421001, Peoples R China.
关键词：
mass sensor;orthotropic plate model;molecular dynamic simulation;fundamental frequency;black phosphorus
摘要：
Recently, anisotropic black phosphorus (BP) has been reported to have significant physical and mechanical properties, and BP-based mass sensors have the latent applications in detecting the mass of nanoparticles attached on BP. In this paper, an orthotropic plate model (OPM) attached concentrated mass and molecular dynamics (MD) simulations are adopted to investigate the dynamic characteristics of rectangular single-layered BP-based (RSLBP-based) mass sensors. The influences of mass, position of the attachment and RSLBP size on the fundamental frequency of RSLBP-based mass sensor are discussed. The results show that when attachment mass increases, or the position of attachment moves from the edge to the middle of RSLBP, the fundamental frequency of the RSLBP-based mass sensor decreases. The fundamental frequency of RSLBP-based mass sensors decreases more significantly with increasing the attachment mass when the size of RSLBP is very small. The results calculated by OPM attached concentrated mass are agreed well with the results calculated by MD simulations, which indicates that the OPM attached concentrated mass can forecast the dynamic characteristics of RSLBP-based mass sensors significantly.
期刊：
International Journal of Quantum Chemistry,2023年123(8):e27072- ISSN：0020-7608
通讯作者：
Xijun Wu<&wdkj&>Xijun Wu Xijun Wu Xijun Wu
作者机构：
[Wu, Feihong; Zhang, Yang; Zhou, Nan; Yu, Wantang] Univ South China, Sch Nucl Sci & Technol, Hengyang, Peoples R China.;[Wu, Xijun; Cheng, Jinjuan; Qin, Yong; Tan, Jie] Univ South China, Sch Math & Phys, Hengyang, Peoples R China.;[Wu, Xijun] Univ South China, Sch Math & Phys, Hengyang 421001, Peoples R China.
通讯机构：
[Xijun Wu; Xijun Wu Xijun Wu Xijun Wu] S;School of Mathematics and Physics, University of South China, Hengyang, China
关键词：
adsorption;BC3;C3N;Cs;graphene
摘要：
Density functional theory (DFT) was used to conduct a systematic analysis of the adsorption characteristics of Cs on three two-dimensional materials: graphene, C3N, and BC3. The adsorption energies of Cs were calculated, and the electronic structure of the system was analyzed. The dependence of adsorption energies on temperatures was taken into account, and the first-principles-derived adsorption energies were used to calculate the influence of temperature on the adsorption rate. It was discovered that BC3 is more stable than the other two materials, has good adsorption characteristics, and has performance that is not significantly degraded at high temperatures. The adsorption performances of other radionuclides I and Ag (which also have radionuclides) on BC3, were also calculated to compare with that of Cs. The results show that the adsorption capacity of Cs on BC3 is much greater than that of the two lighter elements. Based on this study, BC3 is a good candidate for removing Cs from nuclear wastewater.
摘要：
First‐principles calculations show that black phosphorene (BP) exhibits strong adsorption with uranium and thorium atoms even when the temperature reaches 500 and 673 K. The strong adsorption is stabilized by the p‐d coupling between the phosphorus and actinide atoms. BP is an ideal adsorption and separation material for actinides with promising potential applications such as uranium extraction from seawater. Abstract Density functional theory (DFT) calculations were carried out in this work to systematically investigate the adsorption properties of monolayer black phosphorene (BP) for actinide uranium (U), thorium (Th), and plutonium (Pu) atoms. More specifically, the linear response method was used and the Hubbard U values of 2.97 and 2.61 eV were fitted describing the strong lattice point Coulomb interactions of the U and Pu 5f orbitals, respectively. From the DFT + U calculations, it was demonstrated that the U, Th, and Pu atoms can be favorably adsorbed on the hollow sites of the BP surface, with an adsorption energy of 3.48, 4.93, and 0.98 eV, respectively. By analyzing the electronic structure, charge transfer, and highest occupied molecular orbital, it was revealed that the U and Th adatoms can induce the generation of impurity states within the band gap of BP and stabilize their adsorption by strong p‐d coupling with the phosphorus atoms. In addition, from the electron–phonon coupling calculations, it was revealed that the temperature for the stable adsorption of the U and Th adatoms can reach as high as 500 and 673 K. By using the adsorption rate equation, the critical temperature for the adsorption–desorption transition of U and Pu adatoms was estimated to be 632 and 185 K, respectively, while the Th adatom did not tend to desorb. Our results clearly indicate that BP is an ideal adsorption and separation material for actinides with promising potential applications, such as uranium extraction from seawater.
关键词：
Wind power;Green hydrogen;Grey hydrogen;Potential for substitution
摘要：
The predominant utilization of fossil fuels for hydrogen production in China leads to substantial carbon emissions, posing a challenge to China's objective of achieving carbon neutrality. With the rapid development of wind power in China, hydrogen can be produced through water electrolysis powered by wind-generated electricity. This process offers the potential to gradually replace the hydrogen production from fossil fuel (grey hydrogen), thus promoting the low-carbon transformation of China's hydrogen energy industry. However, further investigation is required to determine the potential displacement of grey hydrogen through the production of hydrogen from wind power in China in the future. To address this issue, this study first obtained wind speed data for the entire China region from the MERRA-2 database. Subsequently, based on the wind speed data for each specific area, the wind turbine model with the lowest power generation cost was selected from the eight available wind turbine models. On this basis, the mixed integer linear programming method is used to construct the cost analysis model of wind power-hydrogen production (WPHP). Based on the local wind power generation data, calculations are performed to determine the optimal installed capacity of the wind turbine, electrolyzer, and hydrogen storage tank within the WPHP system. Additionally, the optimal scheduling of the WPHP system is determined. These optimizations collectively result in the best WPHP cost. Based on this research, the optimal cost of WPHP for each geographical grid in China can be calculated and compared with the local grey hydrogen cost. The analysis reveals that in some areas of Xinjiang, Gansu, and Guizhou, exhibit low costs of wind power. This suggests that the substitution of grey hydrogen with WPHP can be achieved in these areas. Based on technological progress and changes in carbon trading prices, this paper predicts that WPHP in China could potentially replace 16.35–28.69 million tons of grey hydrogen by 2040. Moreover, by 2060, WPHP in China is projected to replace 76.72–92.01 million tons of grey hydrogen. According to the sensitivity analysis conducted, it has been determined that the efficiency of the electrolyzer and the price of the wind power equipment exert the greatest impact on the cost of hydrogen production.
期刊：
Biomedical Signal Processing and Control,2023年80:104266 ISSN：1746-8094
作者机构：
[Liu, Yatao] Chongqing Coll Mobile Commun, Chongqing Key Lab Publ Big Data Secur Technol, Chongqing 401420, Peoples R China.;[Liu, Yatao] Univ South China, Coll Math & Phys, Hengyang 421001, Peoples R China.
关键词：
Advection-diffusion–reaction equation;Atherosclerosis;Finite element method;Porosity
作者机构：
[Luo, Qing-Qing; Zhang, Yue; Chen, Xue-Kun; Chen, Xue] Univ South China, Sch Math & Phys, Hengyang 421001, Peoples R China.;[Luo, Qing-Qing; Zhang, Yue; Chen, Xue-Kun; Chen, Xue] Univ South China, Hunan Key Lab Math Modeling & Sci Comp, Hengyang 421001, Peoples R China.;[Jia, Pin-Zhen; Jia, PZ] Hunan Inst Technol, Dept Math & Phys, Hengyang 421002, Peoples R China.;[Zhou, Wu-Xing; Zhou, WX] Hunan Univ Sci & Technol, Sch Mat Sci & Engn, Xiangtan 411201, Peoples R China.;[Zhou, Wu-Xing; Zhou, WX] Hunan Univ Sci & Technol, Hunan Prov Key Lab Adv Mat New Energy Storage & Co, Xiangtan 411201, Peoples R China.
通讯机构：
[Jia, PZ ; Zhou, WX ] H;Hunan Inst Technol, Dept Math & Phys, Hengyang 421002, Peoples R China.;Hunan Univ Sci & Technol, Sch Mat Sci & Engn, Xiangtan 411201, Peoples R China.;Hunan Univ Sci & Technol, Hunan Prov Key Lab Adv Mat New Energy Storage & Co, Xiangtan 411201, Peoples R China.
摘要：
As representative semiconducting hexagonal carbon-boron-nitride lattices, C6BN and C2BN are experimentally realized two-dimensional (2D) plane materials and have recently become the focus of research. Herein, combining first-principles calculations with the Boltzmann transport equation, we performed a comprehensive study on the phonon interaction and thermal conductivity in C6BN and C2BN monolayers. It is found that the thermal conductivities of C6BN and C2BN monolayers at room temperature are reduced by 79% and 73%, respectively, due to four-phonon scattering, compared with the results including three-phonon scattering only. We can attribute this phenomenon to giant four-phonon scattering exclusive for the heat-carrying out-of-plane acoustic (ZA) phonons, because the reflection symmetry allows four-ZA processes much higher than three-ZA processes, and the quasiparallel behavior between the ZA and low-lying out-of-plane optical (ZO) branches contribute to a broad phase space for four-phonon scattering as well. Moreover, C6BN monolayer exhibits unusual behavior that optical phonons contribute about similar to 60% to the overall thermal conductivity under the four-phonon picture, which differs from the traditional case that acoustic phonons dominate thermal conductivity. Unexpectedly, two low-lying ZO modes have as high as 38% contributions to the thermal transport at 300 K under the four-phonon picture, causing 60% contribution of optical phonon modes, apparently larger than that of the three-phonon case (15%) and many other 2D materials, also indicating the four-phonon scattering has a more significant effect on acoustic phonons than on optical phonons. This finding not only highlights insight into the nature of phonon transport, but also provides a promising strategy for manipulation of heat transport based on optical phonon modes.
摘要：
In this paper, a six-neuron incommensurate fractional order BAM neural network model with multi-delays is considered. We demonstrate that the equilibrium point of the system loses its stability and Hopf bifurcation emerges when the delay passes through a critical value. And the relationship between the critical delay of Hopf bifurcation and size of fractional orders is found. Finally, some numerical simulations are given to verify the validity of the theoretical results.
期刊：
MATHEMATICAL MODELLING OF NATURAL PHENOMENA,2023年18:11-null ISSN：0973-5348
作者机构：
[Chen, Xuekun; Xie, Yaqian; Hu, Jiwen; Lei, Weirui; Liu, Can] Univ South China, Coll Math & Phys, Hengyang 421001, Peoples R China.
关键词：
Statins;atherosclerosis;necrotic core volume;finite element method
摘要：
A large necrotic core increases the risk of atherosclerotic plaque instability. Statins can delay the growth of necrotic core in plaques, but the kinetic mechanism of statins in slowing down the necrotic core has not yet been addressed in detail. In this paper, a mathematical model is governed by a system of advection-diffusion-reaction equations coupling of the porous nature of vessel wall is established and applied to illustrate the plaque growth with lipid-rich necrotic core (LRNC) with and without statins using finite element method. We study the influence of LRNC plaque growth for different drug concentrations at different time intervals. The results showed that the drug use at different time points has a significant impact on the treatment efficacy. Compared with short-term, low-dose treatment, early statin treatment with high dose showed more pronounced effects on reducing the low-density lipoprotein (LDL) cholesterol, decreasing the volume of necrotic core, changing the characteristics of plaques, and improving the plaque stability. The model is validated by comparing with the clinical data, and may be used to predict the progression of LRNC plaque and the effects of statin therapy.
