A Three-Dimensional Infinite Collapse Map with Image Encryption

Chaos is considered as a natural candidate for encryption systems owing to its sensitivity to initial values and unpredictability of its orbit. However, some encryption schemes based on low-dimensional chaotic systems exhibit various security defects due to their relatively simple dynamic characteristics. In order to enhance the dynamic behaviors of chaotic maps, a novel 3D infinite collapse map (3D-ICM) is proposed, and the performance of the chaotic system is analyzed from three aspects: a phase diagram, the Lyapunov exponent, and Sample Entropy. The results show that the chaotic system has complex chaotic behavior and high complexity. Furthermore, an image encryption scheme based on 3D-ICM is presented, whose security analysis indicates that the proposed image encryption scheme can resist violent attacks, correlation analysis, and differential attacks, so it has a higher security level.     

Effect of the Ionic Strength on Collapse Transition in Star-like Polyelectrolytes

We present an analytical theory describing intramolecular conformational transition in a star-shaped polyelectrolyte (PE) molecule induced by a decrease in the solvent strength or/and increase in the ionic strength in the solution. We apply a mean-field Flory-type analysis in a box-like approximation, that is we assume fairly uniform distribution of densities of charged monomer units and all mobile ions (co- and counterions) in the intra-molecular volume of the star. We demonstrate that depending on the number of branches, fraction of charged monomers in the star and the ionic strength of the solution different scenario of the collapse transition may take place. At high ionic strength or low degree of ionization collapse transition occurs continuously resembling the collapse of a neutral polymer star. 1 On the contrary, at low ionic strength and high degree of ionization collapse transition features first order phase transition, that is, occurs discontinuously and involves coexistence of collapsed and stretched states.     

Two-fluid smoothed particle hydrodynamics simulation of submerged granular column collapse

In this paper, a two-fluid smoothed particle hydrodynamics (SPH) model, based on the mixture theory, is employed to investigate the complex interactions between the solid particles and the ambient water during the process of submerged granular column collapse. From the simulation, two regimes of the collapse, one being quick and the other being slow, are identified and the reasons of formation are analyzed. It is found that, a large internal friction angle of the granular phase, representing large drag force between solid particles, helps form the slow regime. Small hydraulic conductivity, representing large inter-phase drag force, also retards the collapse dramatically. Good agreements between our numerical results and other researchers’ numerical and experimental results are observed, which demonstrates the capability of the proposed two-fluid SPH approach in dealing with saturated water–soil mixture flows.     

Xe原子的等核及等电子系列离子径向波函数的性态研究

基于相对论多组态Dirac-Fock方法(MCDF方法),详细研究了Xe及类Xe离子的束缚和连续的f轨道波函数的性态,分析了沿等核系列和等电子系列f轨道径向波函数的塌缩现象.在此基础上,进一步讨论了轨道波函数的塌缩导致的强弛豫效应及其对类Xe离子的4d10-4d94f跃迁能和振子强度的影响.     

Gravitational Collapse without a Remnant

We investigate the gravitational collapse of a spherically symmetric, inhomogeneous star, which is described by a perfect fluid with heat flow and satisfies the equation of state p=ρ/3 or p=C ρ ^γ at its center. Different from the ordinary process of gravitational collapsing, the energy of the whole star is emitted into space. And the remaining spacetime is a Minkowski one at the end of the process.     

Dynamical symmetry breaking of lambda- and vee-type three-level systems on quantization of the field modes

We develop a scheme to construct the Hamiltonians of the lambda-, vee- and cascade-type three-level configurations using the generators of SU(3) group. It turns out that this approach provides a well-defined selection rule to give different Hamiltonians for each configuration. The lambda- and vee-type configurations are exactly solved with different initial conditions while taking the two-mode classical and quantized fields. For the classical field, it is shown that the Rabi oscillation of the lambda model is similar to that of the vee model and the dynamics of the vee model can be recovered from lambda model and vice versa simply by inversion. We then proceed to solve the quantized version of both models by introducing a novel Euler matrix formalism. It is shown that this dynamical symmetry exhibited in the Rabi oscillation of two configurations for the semiclassical models is completely destroyed on quantization of the field modes. The symmetry can be restored within the quantized models when both field modes are in the coherent states with large average photon number which is depicted through the collapse and revival of the Rabi oscillations.      

公路隧道特大塌方成因分析及综合处治方法研究

结合元磨高速公路大风垭口隧道工程在施工过程中下行线K255+283出现的特大塌方事故,论文综合分析认为该段位于断层突泥富水带且塌方发生前曾发生涌水、塌方,在此基础上提出地表与洞内处治相结合并加以洞内排水的综合处治措施,综合监测和评判结果表明,综合处治后,塌方断面附近初期支护及二次衬砌的受力及变形均未发生异常变化,有关应力和变形在经过一段时间的变化后最终趋于稳定,而且其相关变化值都在很大的允许范围内,证明处治措施不仅理论上可靠,而且现实中安全可行,对未来公路隧道施工塌方处治工作有所指导和借鉴作用。     

Investigation of passivation effects in AlGaN/GaN metal-insulator-semiconductor high electron-mobility transistor by gate-drain conductance dispersion study

This paper studies the drain current collapse of AlGaN/GaN metal-insulator-semiconductor high electron-mobility transistors (MIS-HEMTs) with NbAlO dielectric by applying dual-pulsed stress to the gate and drain of the device.For NbAlO MIS-HEMT,smaller current collapse is found,especially when the gate static voltage is 8 V.Through a thorough study of the gate-drain conductance dispersion,it is found that the growth of NbAlO can reduce the trap density of the AlGaN surface.Therefore,fewer traps can be filled by gate electrons,and hence the depletion effect in the channel is suppressed effectively.It is proved that the NbAlO gate dielectric can not only decrease gate leakage current but also passivate the AlGaN surface effectively,and weaken the current collapse effect accordingly.     

场板结构AlGaN/GaN HEMT的电流崩塌机理

在不同的漏偏压下,研究了钝化和不同场板尺寸AlGaN/GaN HEMT对电流崩塌的抑制能力.实验结果表明,钝化器件对电流崩塌的抑制能力随着漏偏压的升高而显著下降;在高漏偏压下,场板的尺寸对器件抑制崩塌的能力有较大影响,而合适尺寸的场板结构在各个漏偏压下都能够很好的抑制电流崩塌.深入分析发现,场板结构不仅能够抑制虚栅的充电过程,而且提供了放电途径,有利于虚栅的放电,从而抑制电流崩塌.在此基础上,通过建立场板介质对虚栅放电的模型,解释了高漏偏压下场板的尺寸对器件抑制崩塌的能力有较大影响的原因. 关键词： AlGaN/GaN HEMT 场板 电流崩塌     

Gravitational collapse in higher-dimensional charged-Vaidya space-time

We analyze here the gravitational collapse of higher-dimensional charged-Vaidya spacetime. We show that singularities arising in a charged null fluid in higher dimension are always naked violating at least strong cosmic censorship hypothesis (CCH), though not necessarily weak CCH. We show that earlier conclusions on the occurrence of naked singularities in four-dimensional case can be extended essentially in the same manner in 5D case also