Optimal harvesting strategy of a stochastic inshore–offshore hairtail fishery model driven by Lévy jumps in a polluted environment

Nonlinear Dynamics - With the increasing demand for aquatic products all over the world, exploring the interactions between inshore and offshore fisheries is one of the meaningful issues to help...     

Ring Airy-Like Beams along Predesigned Parabolic Trajectories

By phase-modulating ring Airy Gaussian beams, ring Airy-like beams propagating along predesigned parabolic trajectories are presented which combine the properties of accelerating beams and abruptly autofocusing beams analytically and numerically for the first time. The enhancement of the quadratic term ratio α shortens the autofocus distance and increases the slope of the beams after autofocusing. Interestingly, the main lobe tends to break into pieces as α increases and the possible reasons have been discussed. Furthermore, the distribution factor β and the radius of the primary r₀ can prominently affect the autofocus distance and the intensity at the focal point but do not change the slope of the beams after the autofocusing. In addition, the self-healing properties are validated to be retainable while RAiG beams via predesigned parabolic trajectories with various α.     

Dissipative quantum phase transition in a biased Tavis-Cummings model

We study the dissipative quantum phase transition(QPT)in a biased Tavis–Cummings model consisting of an ensemble of two-level systems(TLSs)interacting with a cavity mode,where the TLSs are pumped by a drive field.In our proposal,we use a dissipative TLS ensemble and an active cavity with effective gain.In the weak drive-field limit,the QPT can occur under the combined actions of the loss and gain of the system.Owing to the active cavity,the QPT behavior can be much differentiated even for a finite strength of the drive field on the TLS ensemble.Also,we propose to implement our scheme based on the dissipative nitrogen-vacancy(NV)centers coupled to an active optical cavity made from the gainmedium-doped silica.Furthermore,we show that the QPT can be measured by probing the transmission spectrum of the cavity embedding the ensemble of the NV centers.     

The role of the local environment in determining the sizes of the magnetic moments in Fe3Al

A local environment approach is used to calculate the sizes of the magnetic moments in ordered Fe₃Al. A simple model based on a LCAO model and Stoner theory gives results in good agreement with experiment. Calculations were performed self-consistently using the recursion method. The role of the aluminium is investigated and it is shown that it is essential to include the aluminium sp band but the results are insensitive to its details.     

KrF激光泵浦H2受激拉曼放大

利用KrF激光泵浦高压H_2,在同轴前向的受激拉曼散射(SRS)作用下,产生受激拉曼放大,1阶Stokes光对泵浦光的转换效率为17.2％,并对影响放大过程和转换效率的若干因素作了分析。     

带息力更新风险模型的一个极值分布

本文讨论了带息力的更新风险模型,得到了破产前最大盈余分布的递推公式,且在此基础上还给出了它满足的积分方程.     

Diophantine vectors in analytic submanifolds of Euclidean spaces

Let M be an m-dimensional analytic manifold in R~n.In this paper,we prove that almost all vectors in M (in the sense of Lebesgue measure) are Diophantine if there exists one Diophantine vector in M.     

Behavior of concrete cylinders confined by carbon-composite tapes and prestressed yarns 1. Experimental data

The results of a comprehensive test program for the mechanical behavior of round concrete specimens confined by carbon-fiber epoxy tapes and prestressed carbon yarns are reported. Five different concrete batches of compressive strength from 20 to 100 MPa and the confinement of various thickness and pretension level were investigated. The specimens, which were subjected to monotonic or repeated compressive loadings, showed a nonlinear stress-strain behavior with a significant ductility and increased ultimate strength, in contrary to the brittle behavior of plain concrete. The limit of linearity on the stress-strain diagrams of the confined concrete roughly coincided with the ultimate strength of plain concrete. Above this limit, the damage accumulation and plastic deformations proceeded in the confined specimens. This fact was evidenced by the increasing slope of deformation diagrams in unloadings and repeated loadings and by the pronounced residual strains. The limit of linearity could be raised significantly by pretension of the carbon yarns during their winding. Russian translation published in Mekhanika Kompozitnykh Materialov, Vol. 42, No. 1, pp. 21–44, January–February, 2006.     

RCCo_3(CO)_9的电化学和RCCo_3(CO)_9~-的ESR谱研究

本文对三种RCCo_3(CO)_9及相应的自由基进行了电化学和ESR谱研究.电化学研究表明,RCCo_3(CO)_9被还原为自由基的难易与R的性质有关,RCCo_3(CO)_9在室温下可以稳定存在.在对分子轨道对称性分析的基础上对簇合物自由基的ESR谱进行了讨论.确定了超精细偶合常数的符号和未成对电子占据轨道的性质,计算了Co的3d轨道和4s轨道的自旋密度.     

The fluorescence properties of Yb3+ and Er3+ Co-doped YAl3(BO3)4 powders prepared by sol-gel method

Yb³⁺ and Er³⁺ co-doped YAB powders were prepared by sol-gel method. The structure and fluorescence properties were investigated. XRD pattern indicated that the single phase was obtained at 1150°C and the structure belonged to rhombohedral. Under 379 nm excitation, two emissions around 983 nm and 1531 nm were observed and the effect of Yb³⁺ ion concentration on the emission intensity was discussed. The energy transfer was observed under 930 nm excitation and the energy transfer efficiencies for all samples were calculated. The lifetimes of ² F _5/2 level of Yb³⁺ ion and ⁴ I _13/2 level of Er³⁺ ion were measured and the effect of Yb³⁺ ion concentration on the lifetime was also discussed. The results indicated that there was an additional mechanism for the decay of ⁴ I _13/2 level in powder samples. The Yb³⁺ and Er³⁺ co-doped YAB powders should be a potential candidate for ceramic laser materials.