考虑损伤的粘弹性梁的纯弯曲

根据粘弹性损伤理论,分析了带损伤粘弹性矩形梁在受纯弯曲时损伤对应力的影响,得到了在Laplace变换域内损伤场和应力场的分布．利用Laplace数值逆变换,分别得到了损伤弹性梁和损伤粘弹性梁的最大应力和最大损伤值,分析了材料的粘性对梁内应力和损伤的影响。     

大口径火炮焊接药筒射击变形机理的启发式反演

在某大口径火炮焊接钢药筒退壳后残余变形实际测量现象规律的基础上,运用非线性有限元分析作为物理模型正问题分析工具,对火炮发射过程中影响该药筒行为的关键因素和作用机理进行启发式反演。通过有限元反演计算,揭示了筒体上热冲击引起的瞬态温升是决定药筒残余变形和抽壳阻力的一个关键因素,得到了筒体瞬态温度增量分布规律。在此基础上通过有限元分析获得的药筒抽壳阻力与实际测试结果一致。     

Influence of terminal alkyl chain length on helical twisting property of chiral 1,2-propanediol derivatives

In this study,a novel series of chiral 1,2-propanediol derivatives with different terminal alkyl chain length were synthesized and characterized by FT-IR,~1H NMR and DSC.After doped into a nematic liquid crystal host,all the chiral dopants induced chiral nematic liquid crystals exhibiting a helix inversion with temperature variation.The results indicate that terminal alkyl chain length has a prominent influence on helical twisting property of the chiral dopants.With increasing the terminal alkyl chain le...     

Distribution algorithm in finite difference method and its application to a 2D simulation of temperature inversion

In this article we present a numerical algorithm in a finite difference method coupled with the Schwartz distribution on a surface and its application to 2D simulation of a temperature inversion in meteorology. This phenomenon has been observed in Kyoto in Japan frequently and one of the reasons why the inversion occurs is the radiative cooling on the ground. In order to describe it in a mathematical model, we introduce transmission conditions on the ground and show its distribution formula. The characteristics of our numerical method are based on the direct method and the finite difference approximation of the Schwartz distribution defined on the ground. Through our discussion, a numerical experiment for the inversion of the temperature gradient is presented.     

Acceleration of the convergence of the Laguerre series in the problem of inverting the Laplace transform

When the Laplace transform is inverted numerically, the original function is sought in the form of a series in the Laguerre polynomials. To accelerate the convergence of this series, the Euler-Knopp method is used. The techniques for selecting the optimal value of the parameter of the transform on the real axis and in the complex plane are proposed.     

High throughput study of phase inversion parameters for polyimide-based SRNF membranes

High throughput (HT) techniques were applied for the first time for a detailed study of parameters involved in a phase inversion process. The synthesis of integrally skinned asymmetric polyimide (Matrimid^®) membranes was investigated. In spite of being one of the most important materials of reference in solvent resistant nanofiltration (SRNF), a detailed study of the phase inversion parameters for this system is still missing. Phase inversion parameters were selected both on the level of the composition of the casting solution (polymer concentration, solvent type, co-solvent/solvent weight ratio, non-solvent content) as on the level of the post-casting (evaporation time) and immersion (composition coagulation medium) conditions. The study of this extensive parameter space was conducted in a HT-fashion, in which the entire membrane preparation and testing process was miniaturized, parallellized and automated. Thanks to the availability of reliable HT techniques at all levels (i.e. preparation of polymer solutions, membrane casting and membrane testing), 145 membranes were prepared and tested (in triplicate) in the separation of the dye rose Bengal from 2-propanol within a time frame of a few months, meaning a dramatic improvement in time- and cost-efficiency. An attempt was made to link the SRNF performances of the prepared membranes and their SEM-observed morphologies more fundamentally to the phase inversion parameters through the use of Hansen solubility parameters and viscosity measurements.     

Global exponential convergence and stability of gradient-based neural network for online matrix inversion

Wang proposed a gradient-based neural network (GNN) to solve online matrix-inverses. Global asymptotical convergence was shown for such a neural network when applied to inverting nonsingular matrices. As compared to the previously-presented asymptotical convergence, this paper investigates more desirable properties of the gradient-based neural network; e.g., global exponential convergence for nonsingular matrix inversion, and global stability even for the singular-matrix case. Illustrative simulation results further demonstrate the theoretical analysis of gradient-based neural network for online matrix inversion.     

Dynamic responses of shear flows over a deformable porous surface layer in a cylindrical tube

This paper investigates dynamic responses of a viscous fluid flow introduced under a time dependent pressure gradient in a rigid cylindrical tube that is lined with a deformable porous surface layer. With the Darcy’s law and a linear elasticity assumption, we have solved the coupling effect of the fluid movement and the deformation of the porous medium in the Laplace transform space. Governing equations are deduced for the solid displacement and the fluid velocity in the porous layer. Analytical solutions in the transformed domain are derived and the time dependent variables are inverted numerically using Durbin’s algorithm. Interaction between the solid and the fluid phases in the porous layer and its effects on fluid flow in tube are investigated under steady and unsteady flow conditions when the solid phase is either rigid or deformable. Examples are presented for flows driven by a Heaviside or a sinusoid pressure gradient. Significant effects of the porous surface layer on the flow in the tube are observed. The analytical solutions can be used to test more complicated numerical schemes.     

纤维素微孔锂电隔膜的制备及性能研究

为了改善锂电隔膜的亲液性和耐高温性,以醋酸纤维素为成膜材料,利用相转化法制备了新型锂电隔膜,通过形貌和孔道结构表征、亲液性能和耐热性能测试对醋酸纤维素隔膜的基本性能进行研究,并将该隔膜装配成锂离子电池进行充放电性能测试. 结果表明,醋酸纤维素隔膜具有均匀的微孔结构,孔隙率达到65%,约为传统聚烯烃隔膜的1.5倍;纤维素材料的良好亲液性和高孔隙率结构改善了隔膜的吸液性能,其吸液率达到285%;该隔膜在150 ^oC、30 min的热处理条件下未发生明显的热收缩. 鉴于上述优点,相对于市售PE隔膜,醋酸纤维素隔膜所装配锂离子电池显示出更优的循环性能和倍率性能.     

量子Zeno效应对原子布居翻转的影响

在量子信息的研究中,量子Zeno效应（QZE）的研究对量子信息的处理有重要作用.针对原子—场相互作用系统,在Jaynes Cummings ( JC) 模型下,研究在不同测量时间间隔中, 布居翻转与初态存活概率的变化趋势.同时得出在时间间隔足够小时,产生QZE,进而得出QZE对布居翻转的影响.