A novel method for solving a class of singularly perturbed boundary value problems based on reproducing kernel method

In this paper, a novel method is presented for solving a class of singularly perturbed boundary value problems. Firstly the original problem is reformulated as a new boundary value problem whose solution does not change rapidly via a proper transformation; then the reproducing kernel method is employed to solve the boundary value new problem. Numerical results show that the present method can provide very accurate analytical approximate solutions.     

微喇曼和红外光谱法研究化学气相沉积金刚石多晶膜结晶质量特性

研究了化学气相沉积多晶膜的宏观性能（颜色和透光性）与微观性能（结晶质量、相纯度和氢杂质含量）之间的关系,喇曼谱与金刚石膜中氢杂质含量（红外光谱测得）的关联性.给出了根据颜色和透明度来区分样本膜质量的实验依据,颜色较深的膜的结晶质量差、相纯度低、氢杂质含量高,1 332 cm－1金刚石特征喇曼峰强度低,半峰宽大.由于多晶膜生长不均匀性、多晶以及粗糙度的影响,生长面的微喇曼光谱随采样点变化会产生较大的偏差,而光滑生长界面的喇曼光谱随采样点的变化偏差较小,因此生长界面的喇曼光谱更能反映化学气相沉积法制备金刚石膜的整体质量.     

Study on the structural characteristics of HgCdTe photodiodes using laser beam-induced current

The structural characteristics of typical n⁺-on-p HgCdTe photodiodes have been studied by laser beam-induced current (LBIC). The dependence of LBIC on laser wavelength, junction depth and localized leakage has been presented. The diffusion length of minority carrier of p-type region is extracted by the exponential decay fitting of the curve of LBIC. It is found that the peak magnitude of LBIC and junction depth approximate to a linear relationship for practical values of device fabrication. The diffusion length monotonously increases with the junction depth. A notable shift of LBIC profile is observed when localized leakage exists. This provides a useful explain for LBIC applying to characterize the structure and process uniformity of HgCdTe infrared detectors.     

Analysis of a predator-prey model with modified Leslie-Gower and Holling-type II schemes with stochastic perturbation

In this paper, we consider a predator-prey model with modified Leslie-Gower and Holling-type II schemes with stochastic perturbation. We show there is a unique positive solution to the system with positive initial value, and mainly investigate the long time behavior of the system. Condition for the system to be extinct is given and persistent condition is established. At last, numerical simulations are carried out to support our results.     

环己烷甲酸根桥联的二维锰配合物的合成与表征

Complex [Mn₂(C₆H₁₁CO₂)₃(4,4′-bipy)₂(H₂O)₂]ClO₄ (C₆H₁₁CO₂H=cyclohexanecarboxylic acid) was synthesized by reaction of Mn(ClO₄)₂·6H₂O, C₆H₁₁CO₂Na and 4,4′-bipy in methanol. The title complex crystallizes in triclinic space group P1, with a=1.008 8(2) nm, b=1.086 3(1) nm, c=1.164 9(3) nm, α=63.016(3)°, β=81.998(4)°, γ=88.604(1)°, V=1.125 4(4) nm³, Z=1. There are two types of Mn atoms in the structure with each in octahedral geometry. Mn1 and Mn2 are bridged by cyclohexanecarboxylate ligands into a chain and the chains are further linked together by 4,4′-bipy into a 2D plane. CCDC: 692247.     

High performance LiNi0.5Mn1.5O4 cathode materials synthesized by a combinational annealing method

High performance LiNi_0.5Mn_1.5O₄ was prepared by a combinational annealing method. All samples were characterized by X-ray diffraction, infrared, and cell measurements. With increasing the annealing time at 600 °C, LiNi_0.5Mn_1.5O₄ showed a decreased lattice parameter and an enhanced Ni-ordering. The electrochemical property of LiNi_0.5Mn_1.5O₄ was optimized by controlling the annealing time. It was found that after annealing at 600 °C for 8 h, LiNi_0.5Mn_1.5O₄ can discharge up to 138 mA h g⁻¹ with a superior cycling performance at the rate of 5/7 C. High-rate test indicated that LiNi_0.5Mn_1.5O₄ exhibited excellent electrochemical performance when charged and discharged at 1.2 C and 2.5 C, respectively. The findings reported in this work are expected to pave the way for the practical application of LiNi_0.5Mn_1.5O₄.     

Multifractality in relativistic charged particles produced at SPS energies

The multifractal analysis of relativistic shower particles produced in ³²S–emulsion interactions at 200 AGeV has been investigated using the method of modified multifractal moments, G_q, in pseudo-rapidity space. The anomalous fractal dimension, d_q, and generalized fractal dimensions, D_q, are determined for the present data for different order of moment. The experimental data reflects multifractal geometry in a multipion production process. The downward concave shape of the multifractal spectral function, f(α_q), gives an evidence for self-similar cascade mechanism. The multifractal specific heat has also been evaluated for the present data using the generalized fractal dimensions, D_q. We compared our experimental results with those obtained from simulated events of the Lund Monte Carlo Code FRITIOF and uncorrelated Monte Carlo events, (MC-RAND) generated randomly in pseudorapidity space based on the assumption of independent emission of particles. The experimental data on multifractality has been found to exhibit a remarkable proximity to the analogous data obtained from the FRITIOF code and the uncorrelated Monte Carlo events.     

Impact of two types of time delays and cross-correlated multiplicative and additive noises on stability and stochastic resonance for a metapopulation system

In this paper, we investigate the stability and the shift between the extinction state and the stable one of a large density and the stochastic resonance (SR) for a metapopulation system subjected to two types of time delay terms, cross-correlation noises and multiplicative signal. By using the fast descent method and the method of small delay approximation, the expressions of the effective potential function and the signal-to-noise ratio (SNR) are obtained. We denote by Q the intensity of the multiplicative noise, and M the intensity of the additive noise, θ and τ the two time delay terms introduced into the metapopulation system. Our main results show some facts that time delay θ and the strength of correlation noise λ can restrain the development of the metapopulation, while the other term of time delay τ can accelerate the expansion of the population from the extinction state to the large stable one. We discover that it is possible to enhance the signal-to-noise ratio by adjusting the intensities of the multiplicative, additive noises and the time delays of the stochastic metapopulation system     

PxSy nanoparticles encapsulated in graphene as highly reversible cathode for sodium ion batteries

Herein, phosphorus-mediated sulfur nanoparticles encapsulated in reduced graphene oxide nanosheets (P-SrGO-T) were successfully synthesized as the cathode for sodium ion battery by a ball milling and the following thermal treatment. A series of covalent bonds, such as P–S, C–S–C, C–O–P and C–S–P, are formed in this process, which are in favor of fixing the sulfur and suppressing the parasitic shuttle effect of polysulfide. Benefiting from the graphene sheets and these covalent bonds, a high reversible capacity of 637.4 mAh/g was achieved in P-SrGO-T after 100 cycles at the current density of 0.2 A/g. In addition, P-SrGO-T also delivers a high-rate capacity (330.7 mAh/g at 5 A/g) attributing to low charge transfer resistance and faster ion diffusion kinetic. This work pushes the progress forward in developing phosphosulfide cathode for sodium ion batteries.     

Chaos and fractal properties induced by noninvertibility of models in the form of maps

Many classes of discrete dynamical systems give rise to models in the form of noninvertible maps. With respect to invertible maps, noninvertible maps introduce a singularity of a different nature: the critical set of rank-one, as the geometrical locus of points having at least two coincident preimages. Such new singularities play a fundamental role in the definition of attractors, basins and their bifurcations. The purpose of this paper is a survey of some fundamental results related to two-dimensional noninvertible maps leading to specific chaotic behaviors, as fractal sets, characterizing irreversibility properties of a class of discrete systems.