影响锂离子电池安全性的因素

锂离子电池的安全性一直是锂离子电池 ,特别是大型锂离子电池研制、生产、使用中的关键性问题 ,通过对锂离子电池的材料、制造工艺以及使用条件等方面的探讨 ,分析影响锂离子二次电池安全性的各种因素     

CO2预处理操作条件对Ni-Co双金属催化剂性能与结构的影响

与传统H₂预处理方法相比,新型H₂+CO₂预处理方法（HCD）能显著提升Ni-Co双金属催化剂的沼气重整活性及抗积碳性能. 考察了HCD预处理操作条件对催化剂性能与结构的影响. 较好的HCD预处理操作条件是在催化剂经H₂处理之后,再用175-200 mL·min^-1的原料气CH₄/CO₂（比例为0：10）在780-800 ℃下还原0.5-1h. 在优化预处理操作条件下对催化剂进行了511 h的耐久性考察,并运用X射线衍射（XRD）、热重-差示扫描量热（TG-DSC）、透射电子显微镜（TEM）等手段对耐久性测试后的催化剂进行了表征. 在511 h 的稳定性实验内,CH₄、CO₂转化率,H₂、CO选择性及H₂/CO体积比分别高达96%、97%,98%、99%及0.98. 催化剂在测试期间的平均积碳速率仅为0.2 mg·g^-1·h^-1. 在该预处理操作参数下,催化剂拥有最好的综合性能和良好的耐久性.     

原子吸收分光光度计检定最佳测试条件的选择

介绍原子吸收分光光度计检定最佳测试条件的选择技巧。     

Vapor–Liquid Jump Conditions within a Porous Medium: Results for Mass and Energy

In this paper, we develop the mass and energy jump conditions for a vapor–liquid boundary within a porous medium. The analysis is restricted to a single fluid component and leads to the appropriate jump conditions for an evaporation front. The condition of local thermal equilibrium is assumed to exist in the homogeneous liquid and vapor regions, but not in the boundary region where rapid changes in the saturation occur.     

薄板有限元广义混合法及克服病态问题研究

以薄板理论的广义混合变分原理为基础,建立了一种适用于薄板弯曲分析的有限元广义混合模式,给出了较实用的选择分裂因子的方法,算例表明有限元广义混合法比常规位移模式的精度高,同时还能克服常规有限元中的某些病态问题。本文还讨论了该法克服常规有限元中某些病态问题的机理。     

Spatial Direct Numerical Simulation of the Large Vortical Structures in Forced Plumes

Direct numerical simulation (DNS) of forced plumes arising frominput of both momentum and buoyancy into an ambient fluid is presented.The large vortical structures in the near field of thermal and reactiveplumes are investigated. Boundary conditions associated with the spatialDNS of open-boundary buoyant flows that are compatible with the modernnon-dissipative, high-order, finite-difference schemes have beendeveloped. The governing equations for flow and combustion at the plumecenterline are put into a special form to circumvent the singularity atthe axis associated with the cylindrical coordinates. Mixing is found tobe stronger in the planar thermal plume than in the axisymmetric case.An explanation is provided based on the vorticity budget. Axisymmetricreactive plumes with a one-step reaction governed by the Arrheniuskinetics have also been studied. The unsteady effects of chemical heatrelease and combustion-induced buoyancy on the flow structures areinvestigated. Budgets of the vorticity transport are examined to revealthe mechanisms leading to the formation and evolution of large vorticalstructures in forced plumes. It is found that volumetric expansion dueto chemical heat release tends to destroy vorticity, whilecombustion-induced buoyancy under the gravitational effect generatesvorticity. The gravitational term in the vorticity transport equation isfound to be the main mechanism for the buoyant flow instability and thedevelopment of counter-rotating vortices in reactive plumes.     

The Number of Solutions of Polynomial-Exponential Equations

We will give explicit bounds for the numberof solutions of polynomial-exponential equations.In contrast to earlier work, the bounds areindependent of the coefficients of the equations,and they are of only single exponential growthin the number of coefficients.     

Extension of the Ahiezer–Kac Determinant Formula to the Case of Real-Valued Symbols with Two Real Zeros

The Fredholm determinant asymptotics for self-adjoint convolution operators on finite intervals with real symbols vanishing on the real axis is studied. Explicit formulae are obtained in the case where the symbol satisfies the generalized zero index condition and has only two simple zeros of analytic type. These formulae are direct extensions of the Ahiezer–Kac–Szegö limit theorem which, in particular, take into account the oscillating character of the asymptotics.     

A novel finite element model for helical springs

A general and accurate finite element model for helical springs subject to axial loads (extension or/and torsion) is developed in this paper. Due to the establishment of precise boundary conditions, only a slice of the wire cross-section needs to be modelled; hence, more accurate results can be achieved. An example application to a circular cross-sectional spring is analysed in detail.     

抛物问题的拉格朗日乘子区域分解法

１．引言 近年来,一类新的非重叠区域分解方法一非匹配网格区域分解法,日益引起人们的广泛兴趣,并已成为当今区域分解方法研究的热门课题。这类区域分解方法的特点是：相邻子区域在公共边（或面）上的结点可以不重合,从而能解决许多传统区域分解方法不便解决的问题（如变动网格问题）．目前主要有两类方法来处理这种区域分解的强非协调性：Ｍｏｒｔａｒ无法（见［１－２］和［９－１０］）和拉格朗日乘子法（见［５］,［８］,［１１］和［１２］）．拉格朗日乘子法比Ｍｏｒｔａｒ无法有明显的优点：（１）界面变量（即拉格朗日乘子）…