渗透蒸发机理研究（Ⅱ）—溶解扩散行为与渗透蒸发性能之间关系的研究

本文通过对渗透蒸发实验和平衡溶解实验的比较研究，定量得到了用ＰＶＡ膜分离乙醇水溶液的渗透蒸发机理的认识，即：（１）平衡溶解度大小影响着渗透通量的大小；（２）平衡溶解组成影响着渗透组成：（３）膜内扩散在渗透蒸发中起着重要作用。     

渗透蒸发传质理论与模型(Ⅱ)溶解行为

系统介绍了描述组分在渗透蒸发膜中溶解行为的模型,如亨利定律和Langmuir吸附等温线、溶解度参数理论、Flory—Huggins理论、UNIQUAC模型、UNIFAC模型等,包括模型形式、适用范围、应用等。     

一类具有交叉扩散的捕食-食饵模型正解的存在性

本文研究一类带有交叉扩散的捕食-食饵模型正解的存在性．首先,利用最大值原理得到了与交叉扩散系数无关的正解的先验估计;其次,建立了当交叉扩散系数充分大时的极限系统;最后,利用局部分歧理论得到了极限系统在半平凡解附近的局部分歧解的存在性,借助全局分歧理论说明了该极限系统的局部分歧解可以延拓为全局分歧解,并且该全局分歧解随着分歧参数在正椎内延伸至无穷．结论表明：当交叉扩散系数充分大时,两物种可以共存．     

碳纳米管内气体吸附与扩散的分子模拟研究

气体在纳米管中的输运具有非连续性的特点,这与宏观条件下稀薄气体的输运类似,同时考虑到纳米管的比表面积非常大,那么吸附气体对输运的贡献就不可忽略。本文基于平衡分子动力学和巨正则蒙特卡洛方法,模拟了不同气体分子在不同直径碳纳米管内的扩散和吸附行为。运用通量相关函数计算了气体的输运扩散系数,并结合稀薄气体动力学推导出了气体的表面扩散系数。结果表明,气体在碳纳米管中的输运扩散系数比克努森公式计算出的结果高数倍甚至十数倍,碳纳米管内吸附分子的表面扩散是气体快速输运的原因,表面扩散系数随表面覆盖度的增大而增大。     

生物膜吸附反应动力学模型与平衡模型的试验研究

采用复合式活性污泥-生物膜反应器,从动力学角度研究生物膜吸附反应动力学模型和吸附平衡模型,以掌握反应控制条件.结果表明,在t≤30min时生物膜的表面吸附阶段,且生物膜附着满足可逆动力学模型;准二级反应模型更能描述生物膜的吸附反应过程;Lang-muir吸附等温线比Freundlich能够更好地说明生物膜良好的吸附性能.     

跳-扩散模型下保险公司的博弈问题

本文研究跳-扩散模型下的具有再保险业务的保险公司非零和博弈问题．假定金融市场可供保险公司投资的金融工具有两种：一种无风险资产（如债券）和一种风险资产（如股票）．保险公司可购买比例再保险,同时再保险公司以期望保费原则收取再保险保费,进而建立描述保险公司盈余过程的跳-扩散模型．以两家保险公司终端财富相对差值绩效最大化为目标,建立了两家保险公司的相对绩效最优的HJB方程．通过博弈理论和随机动态规划的方法,证明两家保险公司竞争纳什均衡解的存在性,并给出了纳什均衡耦合系统的隐式解．在特定的保险公司竞争关系下,对两家保险公司之间的最优投资和再保险策略进行分析,分析了模型参数对最优投资策略的影响,并给出相应的经济解释．     

金属板材轧制-扩散复合机理研究进展

金属板材轧制-扩散复合集合了轧制和扩散连接的特点,对有塑性变形条件下中间层瞬间液相扩散连接过程进行研究,是研究轧制-扩散复合界面结合机理的关键.本文介绍了国内外对瞬间液相扩散连接机理实验、数学模型和数值模拟研究的进展和现状,讨论了存在的一些问题,并提出了解决方法.     

竞争-竞争-互惠交错扩散模型的整体解

竞争-竞争-互惠交错扩散模型是一类强耦合的抛物型方程组,关于该模型时变解的整体存在性的研究结果很少,特别是在高维空间中。本文应用能量估计方法,极值原理和抛物型方程的正则性理论证明了:对竞争种群含弱交错扩散项的竞争-竞争-互惠交错扩散模型,它在任意维空间中存在古典的整体解。     

渗透蒸发传质理论与模型(Ⅲ)扩散模型

系统介绍了描述组分在渗透蒸发膜中的扩散行为的模型,如浓度依赖型扩散系数的经验模型、自由体积理论、双吸附模型、分子模拟等,包括模型形式、适用范围、应用实例等．     

高润滑水凝胶的结构与吸附-排斥作用

水凝胶因具有与天然软骨材料相近的吸水性、高弹性及低摩擦性能,从而成为关节软骨的理想替代材料.介绍吸附-排斥模型及水凝胶的润滑行为,并论述水凝胶的本体结构与水凝胶润滑性能之间的关系.     

Structure features of modified thermally extended graphite

Experimental data on microrelief, elemental composition, and distribution of the modifier over the surface of thermally extended graphite are given. Morphological changes of thermally extended graphite particles induced by the temperature and variations of distribution of cluster formations of the modifier over the thermally extended graphite particle surface depending on the concentration of the initial modifying compound are shown.     

A modified extended finite element method approach for design sensitivity analysis

This paper describes a modified extended finite element method (XFEM) approach, which is designed to ease the challenge of an analytical design sensitivity analysis in the framework of structural optimisation. This novel formulation, furthermore labelled YFEM, combines the well‐known XFEM enhancement functions with a local sub‐meshing strategy using standard finite elements. It deviates slightly from the XFEM path only at one significant point but thus allows to use already derived residual vectors as well as stiffness and pseudo load matrices to assemble the desired information on cut elements without tedious and error‐prone re‐work of already performed derivations and implementations. The strategy is applied to sensitivity analysis of interface problems combining areas with different linear elastic material properties. Copyright © 2015 John Wiley & Sons, Ltd.     

Comparison of a phase‐field model and of a thick level set model for brittle and quasi‐brittle fracture

This paper provides a comparison between one particular phase‐field damage model and a thick level set (TLS) damage model for the simulation of brittle and quasi‐brittle fractures. The TLS model is recasted in a variational framework, which allows comparison with the phase‐field model. Using this framework, both the equilibrium equations and the damage evolution laws are guided by the initial choice of the potential energy. The potentials of the phase‐field model and of the TLS model are quite different. TLS potential enforces a priori a bound on damage gradient whereas the phase‐field potential does not. The TLS damage model is defined such that the damage profile fits to the one of the phase‐field model for a beam of infinite length. The model parameters are calibrated to obtain the same surface fracture energy. Numerical results are provided for unidimensional and bidimensional tests for both models. Qualitatively, similar results are observed, although TLS model is observed to be less sensible to boundary conditions. Copyright © 2015 John Wiley & Sons, Ltd.     

The clock model and its relationship with the Allan and related variances

The clock errors are modeled by stochastic differential equations (SDE) and the relationships between the diffusion coefficients used in SDE and the Allan variance, a typical tool used to estimate clock noise, are derived. This relationship is fundamental when a mathematical clock model is used, for example in Kalman filter, noise estimation, and clock prediction activities.     

Adequacy assessment using a modified four-state model

This paper presents a modified four-state model that can be utilized to assess adequacy at the generation level of a power system. The model can incorporate various operating factors that influence system reliability. A new probabilistic technique that utilizes the model has been developed to evaluate static reserve capacity and margin in a generating system for a given risk criterion. The model can also be utilized in adequacy assessments with deterministic approaches. © 1998 John Wiley & Sons, Ltd.     

能力、知识及与职业教育的关系

能力不仅是基于精神的而且是基于肉体的。知识是能力的组成部分。能力增长依赖于机体组织训练和知识水平提高。获取实际工作能力必须获取相应的感性知识。足够的肢体实践和感性知识积累是职业教育教学的重要特点。     

经典彩色预测模型

针对印刷中原稿和复制品之间存在的色差这一事实,详细介绍了至今为止的几种经典彩色预测模型:如直接针对半色调印刷过程的Neugebauer方程,Yule-Nielsen模型和基于减色原理的Kubelka-Munk理论.通过调节模型中的变量来达到控制色差的目的.     

The relationship of creep,recovery and fatigue in polycarbonate

The quantitative relationship between creep and recovery which had been previously developed by Mindel and Brown [1] has been applied to interrupted creep tests. Single and multiple interruptions (fatigue) were investigated. In general it was observed that interruptions decreased the time to failure. The experiments were conducted in compression in the range of high stresses. Failure was caused by excessive deformation or accelerated creep which is produced by a softening mechanism that is common to all linear polymers. The temperature changes associated with the creep and recovery parts of the cyclic loading were measured. The temperature rise during loading exceeds the decrease during unloading so that there is a net rise in temperature if the creep and recovery intervals are equal. However, the temperature change is not the primary cause for the decrease in time-to-failure for cyclic loading as compared to the failure time during steady stress creep. It has been concluded that fatigue failure under compressive deformation is related fundamentally to the constant stress creep curve.     

The relationship between cracks,holes and surface dislocations

International Journal of Fracture - It has been shown that surface cracks as well as holes can be represented in terms of surface dislocations. These surface dislocations exist in order to insure...