A numerical model for induction heating processes coupling electromagnetism and thermomechanics

This paper presents a mathematical and numerical model developed for coupling the various physical phenomena (electromagnetic, thermal and mechanical) taking place in axisymmetrical induction heating processes. All three electromagnetic, thermal and mechanical models are time dependent and take full account of the electromagnetic and thermal non‐linear effect especially with magnetic materials. The electromagnetic problem is discretized and solved in the workpiece, air and inductors. The heat transfer equation and the mechanical equilibrium equations are solved in the workpiece only, both using a finite element method. The mechanical model can take into account thermoelastic–plastic behaviour for the part. The model has been successfully applied to several cases of induction heating. Comparisons between numerical and experimental results show an excellent agreement. Copyright © 2003 John Wiley & Sons, Ltd.     

凝土温度特性参数反分析及其应用

建立混凝土温度场材料特性参数反演分析模型,并用有限单元法仿真计算和可变容差法编制了优化反演程序。数值算例表明该算法是稳定的,收敛速度较快,并给出具体的在建工程实例的应用情况。通过现场温度观测值,进行优化反演计算得到混凝土温度的有关特性参数,这将成为部分或全部替代仅靠实验室选取参数的行之有效的途径之一。     

数字混沌扩频序列的盲估计

混沌序列具有非线性、宽带类噪声、大的码族、任意长的周期且容易产生的特性,因此在扩频通信系统中很有实用价值。本文将文献[1]中对伪随机扩频序列盲估计的方法推广应用到混沌扩频通信中,并对其不足提出了改进方法。在只知道扩频码周期而无其它任何先验知识的条件下,利用特征值分析的方法可以对数字混沌直扩序列进行盲估计,仿真实验证明了该方法的有效性。     

ECAP细化晶粒法的仿真与分析

ECAP(Equal Channel Angular Extrusion)方法，是实现材料纯剪切变形的有效方法。本文采用有限元（FEA）分析软件ANSYS对Al的挤压过程进行仿真与分析。分析结果表明：外切角Φ、圆角半径、试样与凹模之间的摩擦系数、凹模本身的特性（如弹性模量、泊松比等）等等，对材料的变形量都有不同程度的影响。     

Elastic T-stress solutions for semi-elliptical surface cracks in finite thickness plates

Three-dimensional finite element analyses have been conducted to calculate the elastic T-stress for semi-elliptical surface cracks in finite thickness plates. Far-field tension and bending loads were considered. The analysis procedures and results were verified using both exact solutions and approximate solutions. The T-stress solutions are presented along the crack front for cracks with a/t values of 0.2, 0.4, 0.6 or 0.8 and a/c values of 0.2, 0.4, 0.6 or 1.0. Based on the present finite element calculations for T-stress, empirical equations for the T-stress at three locations: the deepest, the surface and the middle points of the crack front under tension or bending are presented. The numerical results are approximated by empirical formulae fitted with an accuracy of 1% or better. They are valid for 0.2?a/c?1 and 0?a/t?0.8. These T-stress results together with the corresponding K or J values for surface cracks are suitable for the analysis of constraint effects for surface cracked components.     

盐家油田油水井结垢原因探讨

对地层温度65～75℃的盐家油田油水井近井地带、井底、井筒发生严重结垢的原因进行了分析探讨。7口油井采出的地层水均为NaCO3型水．矿化度6．4～10g／L，HCO3浓度高（1．6～3．7g／L），Ca^2＋＋Mg^2＋浓度较低；1口水源井水及1口水井注入水为CaCl2型水，矿化度32～33g／L，Ca^2＋＋Mg^2＋浓度高（3．1～3．8g／L）而HCO3浓度低；采用CaCO3饱和指数法和CaSO4热力学溶解度法预测，在70℃下所有水样均有CaCO3结垢趋势，除3口油井采出的地层水外，均有CaSO4结垢趋势。3口油井采出的地层水与水源水在25℃按不同比例混合后，悬浮物含量大幅度上升。在70℃放置7天后再次大幅度上升，烘干的悬浮物易溶于稀盐酸．其主要成分为碳酸盐．说明注入水、地层水不配伍。1口电泵采油井和1口注水井油管垢样含盐酸可溶物（碳酸盐）超过90％。讨论了碳酸盐、硫酸盐垢的生成条件：温度、压力及pH值。图1表4参3。     

钛基Ru-La-Ti涂层阳极的电催化性能

利用热分解法制备了不同La含量的钛基Ru-La-Ti涂层阳极，并研究了所制备涂层的电催化性能。结果表明，在Ru-Ti涂层阳极中掺杂稀土元素La可以提高涂层阳极的电催化活性，且La的掺杂量存在一个最佳范围(La的摩尔分数O．2)。涂层阳极电催化活性提高的原因在于La的引入可以提高涂层的有效活性表面积。     

一种基于小波变换的OTDR事件分析算法的研究

简单分析了用 OTDR卡进行光纤检测的原理 ,根据小波分析检测信号突变点的理论 ,提出了运用小波分析对光纤断点及反射事件准确定位的方法。理论分析和实例计算表明 ,这种方法对 OTDR曲线中反射事件尤其是断点的定位非常准确 ,是一种行之有效的方法     

Conditions for the Acceptance of Deontic Conditionals.

Recent psychological research has investigated how people assess the probability of an indicative conditional. Most people give the conditional probability of q given p as the probability of if p then q. Asking about the probability of an indicative conditional, one is in effect asking about its acceptability. But on what basis are deontic conditionals judged to be acceptable or unacceptable? Using a decision theoretic analysis, we argue that a deontic conditional, of the form if p then must q or if p then may q, will be judged acceptable to the extent that the p & q possibility is preferred to the p & not-q possibility. Two experiments are reported in which this prediction was upheld. There was also evidence that the pragmatic suitability of permission rules is partly determined by evaluations of the not-p & q possibility. Implications of these results for theories of deontic reasoning are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Neutron Stress Measurement of W‐Fiber Reinforced Cu Composite

Stress measurement methods using neutron and X‐ray diffraction were examined by comparing the surface stresses with internal stresses in the continuous tungsten‐fiber reinforced copper‐matrix composite. Surface stresses were measured by X‐ray stress measurement with the sin²ψ method. Furthermore, the sin²ψ method and the most common triaxal measurement method using Hooke's equation were employed for internal stress measurement by neutron diffraction. On the other hand, microstress distributions developed by the difference in the thermal expansion coefficients between these two phases were calculated by FEM. The weighted average strains and stresses were compared with the experimental results. The FEM results agreed with the experimental results qualitatively and confirmed the importance of the triaxial stress analysis in the neutron stress measurement.