一种经验型疲劳小裂纹扩展模型

金属材料疲劳寿命由裂纹萌生和裂纹扩展寿命两部分组成，其中对于萌生寿命中的小裂纹分析是精确描述裂纹萌生寿命的关键．而小裂纹在扩展过程中由于尺寸相对较小，导致传统线弹性断裂力学预测方法失效，需要对其进行改进，考虑裂纹尖端塑性区引起的残余压应力对小裂纹扩展速度的影响．本文针对此问题进行了初步分析，通过对塑性区引起的残余应力的量化，结合小裂纹门槛值特性，提出了一种经验型修正的小裂纹扩展模型，用于定量预测裂纹的萌生寿命．使用铝合金6082-T6缺口试样进行了疲劳实验，并与理论结果进行了对比，验证了所提模型的有效性．     

Kinetic study of hydrogen sulfide decomposition on Pt(111) surface

In this work, kinetic of H₂S conversion to H₂ molecule on the surface of Pt(111) is studied using kinetic Monte Carlo simulation. The results of simulation were fitted to the experimental temperature-programed desorption spectra. The good agreement between the empirical and the simulated data confirms the proposed mechanism and kinetic data (activated energies and pre-exponential factors). The influence of variables such as temperature and concentrations of H₂S and H₂ on the overall results of hydrogen production is studied. The condition is proposed in which the best yield of reaction at minimum temperature is obtained. Results show that platinum is a perfect catalyst for converting H₂S to H₂ and it has a perfect performance (98%) after 5 μs at low temperature of 227°C.     

Cole-Cole方程参数对细胞介电频谱的影响

为探讨Cole-Cole方程8个参数(Δε1,Δε2,εh,κl,f1,f2,β1,β2)对细胞介电频谱的影响,采用改变单个参数,固定其他参数的方法,观察介电频谱的变化.结果显示:Δε1影响低频介电频谱和Cole-Cole(ε′)图;Δε2影响高频介电频谱、Cole-Cole(ε′)图和Cole-Cole(κ′)图;εh影响ε′(f)、Cole-Cole(ε′)图和tgδ(f);κl对κ′(f)和Cole-Cole(κ′)图有影响;f1影响低频介电频谱;f2影响高频介电频谱;β1影响Cole-Cole(ε′)和tgδ(f);β2对高频介电频谱有影响.可见Cole-Cole方程作为细胞介电频谱的数学模型,其参数变化有规律可循.     

Determination of isospin asymmetry effects on α-decay

In this study,we compared the effect of the isospin asymmetry of proton and neutron density distributions in the neutron skin-type(NST) case and in the Hartree-Fock formalism(HF) on the half-life of alpha emitters with the atomic number in the range of 82≤Z≤92.The NST case and HF formalism based on the Skyrme-SLy4 effective interaction reveal different isospin asymmetries for selected alpha emitters.Furthermore,the obtained results reveal an increase in the α-decay widths of about 30% for the NST case in comparison with the equivalent values obtained by HF formalism.The standard deviations for calculated half-lives within the NST case and HF formalism are about 0.438 and 0.391,respectively.     

Determination of Polysaccharides in Undaria pinnatifida by Ionic Liquid-Modified Silica Gel Size Exclusion Chromatography

Ionic liquid-modified silica particles with a large pore size were synthesized and used as the stationary phase for size exclusion chromatography coupled with a refractive index detector for the determination of polysaccharides, such as fucoidan, alginic acid, and laminarin from Undaria pinnatifida (seaweed). The molecular weight of polysaccharide was determined by a dextran standard curve (5–1100?kDa). The ionic liquid-modified silica column exhibited excellent size exclusion properties in separating laminarin from other components. The 1-butyl-3-methyl-imidazolium bis-(trifluoromethylsulfonyl)-amino silica column has superior resolution in laminarin separation than the other columns because the amino-group in ionic liquid provide π–π interactions due to aromaticity of the ring structure, which enhances the effect of the hydroxyl group in the target compound separation. The concentrations of polysaccharides were calculated using a standard linear equation to be 0.332–0.484?mg/g of fucoidan, 0.207–0.301?mg/g of alginic acid, and 0.154–0.297?mg/g of laminarin.     

Charge transfer ionic character illustration for strontium hydride ion through a diabatic investigation

Adiabatic and diabatic studies are performed for the strontium hydride ion (SrH)⁺. Potential energy surface and electric dipole moment for the ground and all excited states dissociating up to the charge transfer ionic limit Sr²⁺H⁻ have been investigated and analyzed in adiabatic and diabatic representations. The adiabatic approach uses the pseudo potential for the strontium atom complemented by core polarization potential operators, reducing the calculation to a two effective electrons system where full configuration interaction can be easily performed. The adiabatic results have been improved by a simple correction of the hydrogen electron affinity for all ¹Σ⁺ states. The diabatic results reveal the strong imprint of the charge transfer ionic state in the ¹Σ⁺ adiabatic states.     

Two and three-particles spatial correlation in weak coupling plasma and applications

In this work, we studied the pair and triplet correlation functions in plasma composed of particles interacting via the Debye screening potential in the conditions of weak coupling parameter (Γ ≤ 1). The pair correlation functions are analysed numerically and compared to the hypernetted chains data, to the Monte Carlo data and to the results of Abramo and Tosi ??The triplet correlation functions are also analysed numerically and compared to the Kirkwood superposition approximation. At the end of our work, we give some applications to static structure factor and the dielectric constant. The results are well satisfactory.     

Duality Relations for Non-Ohmic Composites, with Applications to Behavior near Percolation

Keller, Dykhne, and others have exploited duality to derive exact results for the effective behavior of two-dimensional Ohmic composites. This paper addresses similar issues in the non-Ohmic context. We focus primarily on three different types of nonlinearity: (a) the weakly nonlinear regime; (b) power-law behavior; and (c) dielectric breakdown. We first make the consequences of duality explicit in each setting. Then we draw conclusions concerning the critical exponents and scaling functions of dual pairs of random non-Ohmic composites near a percolation threshold. These results generalize, unify, and simplify relations previously derived for nonlinear resistor networks. We also discuss some self-dual nonlinear composites. Our treatment is elementary and self-contained; however, we also link it with the more abstract mathematical discussions of duality by Jikov and Kozlov.     

Growth kinetics of CaF2 in a pH-stat fluidized-bed crystallizer

In this study, experiments were first conducted in a stirred vessel to establish the metastable region of calcium fluoride, using a pH-stat apparatus for controlling the pH value of solution. The effects of pH value on the solubility and metastable region were observed. Then, operating variables, including supersaturation, superficial velocity, pH value, seed size, and types of seed and solution, that influenced the crystal growth of the same system were investigated in a fluidized-bed crystallizer. The crystal growth rates were determined from the consumption rates of fluoride ions. The growth kinetics was explored by using the two-step growth model. The effectiveness factor was used to judge whether a controlling step was existing. The kinetics of crystal growth in a lean bed and a dense bed was also discussed.