热镀锌连退过程C翘机理及其预报模型

 为有效降低带钢C翘发生风险,提高其表面镀层均匀性,研究了热镀锌连退过程C翘形成机理。充分考虑到热镀锌连退过程的设备与工艺特点,从弹塑性力学角度详细分析带钢C翘形成机理,并推导出C翘机理力学模型。采用条元法建立带钢C翘预报计算模型,并基于此采用优化递推法成功解决生产应用C翘预报模型难点。最后,在此基础上编制热镀锌机组连退过程带钢C翘预报软件应用于现场,并分别预报两种典型规格带钢在炉内不同工艺段板形翘曲演变过程。结果表明,机组出口板形预报值与其实测值的偏差满足产品精度要求,该模型能实时预测炉内工艺段板形,为后续工艺参数优化提供理论指导,具有进一步推广应用的价值。     

Modification Mechanism of Rare Earth Elements in ZA27 Casting Alloys

The model of the liquid-phase ZA27 alloys was set up by molecular dynamics theory. The atomic structure of phase, RE-compounds, and the phase-liquid interface in ZA27 alloys were constructed by computer programming. Electronic structures of phase with rare earth elements dissolved and of phase-liquid interfaces with rare earth elements enrichment in ZA27 casting alloys were investigated by using the Recursion method. The ESE energy of RE elements and the structure energy of RE-compounds, phase, and the liquid-phase ZA27 alloys were calculated. The results show that rare earth elements are more stable to be in the phase interface than in phase, which explains the fact of very small solid solubility of rare earth elements in phase, and the enrichment in the solid-liquid growth front. This makes dendrite melt and break down, dissociate and propagate. RE-compounds can act as heterogeneous nuclei for phase, leading to phase refinement. All above elucidates the modification mechanism of rare earth elements in zinc-aluminum casting alloys, at electronic level.     

一种提取系统脉冲响应函数的高效的去噪算法

针对锤击激励方式不适用于工业机器人操作臂动态性能测试的情况,根据Duharm a l积分理论,利用系统输入矩阵的上三角形的特殊结构,并结合时域平均技术,导出了具有抗噪性能的高效的求取系统脉冲响应函数的平均递推算法。研究了算法对适合于机器人操作臂测试的阶跃激励方式的适用性,对算法的误差进行了分析。在二自由度动力学模型上进行仿真,与传统的时域解矩阵方法比较,平均递推算法在效率及降噪效果上具有明显的优越性。悬臂梁实验表明,平均递推算法能够获得与锤击法比较一致的结果。     

稀土串级萃取静态递推模型的研究

针对双出口稀土串级萃取分离工艺,建立了两组分静态递推模型。区别于代数模型,首先将萃取过程归结为初始萃取段、置换萃取段、进料级、置换洗涤段、初始洗涤段5种类型,然后建立了各个对象、及对象间的交互关系。利用对象之间的调用和迭代,模型求解速度快于其他模型。分析了萃取液和洗涤液流量波动对稀土产品出口纯度影响的规律,确定了检测点的最佳位置。     

A glimpse into the paradise of combinatory algebra

This expository paper examines combinatory algebra and the lambda calculus as foundations for functional languages (LISP, FP, KRC, etc.,). The basic notions are defined and numerous examples are given. Historical comments and references are provided.     

基于De_Boor递推算法的速度自适应NURBS曲线分段插补算法研究

针对现有大多数NURBS曲线插补算法不能同时满足插补精度和机床加减速性能要求的问题,提出一种基于De_Boor递推算法的速度自适应NURBS分段插补算法。通过前瞻预处理完成插补分段和减速点确定,通过速度修正完成减速段最终插补。MATLAB仿真结果表明,该算法能够同时满足插补精度和机床加减速性能要求。     

A statistical monitoring approach for automotive on‐board diagnostic systems

The current generation of vehicle models are increasingly being equipped with on‐board diagnostic (OBD) systems aimed at assessing the ‘state of health’ of important anti‐pollution subsystems and components. In order to promptly diagnose and fix quality and reliability problems that may potentially affect such complex diagnostic systems, even during advanced development prior to mass production, some vehicle prototypes undergo a testing phase under realistic conditions of use (a mileage accumulation campaign). The aim of this work is to set up a statistical tool for improving the reliability of the OBD system by monitoring its operation during the mileage accumulation campaign of a new vehicle model. A dedicated software program was developed by the authors to filter the large experimental database recorded during the mileage accumulation campaign and to extract the time series of the diagnostic indices to be analysed. A model‐based monitoring approach, using continuous time autoregressive (CAR) models for the time‐series structure and traditional control charts for the estimated residuals, is adopted. A Kalman recursion procedure for the estimation of the unknown CAR model parameters is described. An application of the proposed approach is presented for a diagnostic index related to the state of health of the oxygen sensor. Copyright © 2006 John Wiley & Sons, Ltd.     

黄河中游龙门含沙量过程统计预报模型研究

针对黄河中游吴堡—龙门区间泥沙量过程的特点,基于统计模型方法,建立了多输入、单输出的龙门站含沙量过程预报方案,采用逐步回归方法进行预报因子筛选和模型率定,结合最小二乘递推算法的实时校正技术对含沙量过程进行预报,并根据实测资料对预报方案进行了检验。结果表明,该统计预报方案精度较高、适用性较好。     

A simple linear-time algorithm for in situ merging

It is generally believed that the time-cost of solving any size n problem using two-way divide-and-conquer is minimized by balancing—that is, by dividing the problem into subproblems of size $\text{?}\text{n}\text{2}\text{?}$ and $\text{?}\text{n}\text{2}\text{?}$. A counter-example is presented: balanced division, applied to finding the greatest and least elements of a size n set, will in the worst case force 11% more comparisons to be made than an optimal division such as into subsets of sizes 2 and n?2. A necessary condition and a slightly stronger sufficient condition are given for balancing to be cost-optimal. Even if balancing is cost-optimal, it may not be the only cost-optimal division strategy; a necessary and sufficient condition is given for a division strategy to be ‘balanced enough’ to be cost-optimal. As an application, a new iterative merge-sorting algorithm is presented which requires no more comparisons than the balanced one of Erkio and Peltola (1977) but merges subarrays consisting of consecutive elements of the whole array.     

基于Petri网下递归关系的自控网模型

自控网系统是Petri网系统的一个子类,与P/T系统以及基本网系统相比较,具有更强的描述能力和建模能力。本文运用自控网系统定义了加、减、乘、除四种基本运算以及2个算子的自控网模型,通过逐级抽象建立了直接递归的自控网模型。这种分层逐级抽象的方法体现了利用Petri网形式化软件开发的基本思想。