可变抽样区间的非参数控制图

最近几年一些学者研究了可变抽样区间的质量控制图。Amin等提出了可变抽样区间(VSI)的非参数控制图———符号 (Sign)统计量图〔1〕。本文在此基础上研究位置VSI符号控制图的制定方法 ,并设计离散VSI符号控制图。符号控制图的优点是对非正态总体亦可应用 ,并且不需要过程方差的信息。本文将所设计的VSI符号控制图同固定抽样区间 (FSI)的常规图作比较 ,并举实例说明符号控制图的应用     

质量控制图原理在股票投资组合中的应用研究

质量控制图是用来控制生产过程质量的一种统计方法。其基本理论方法应用到股票投资组合中,可以降低投资风险,提高投资组合的收益率。通过实证研究表明:利用质量控制图原理来确定投资组合的选股、买点和卖点,可以使投资组合获得明显高于大盘指数的收益率,从而验证了质量控制图的基本理论方法完全可以应用于股票投资决策,并且具有显著的实际应用价值。     

Global Structure-Acute Toxicity Relationships for Mice Using Structural Parameter Ratios: New Approach to Molecular Design and Screening

Abstract

A method for a preliminary survey of the relationship between molecular structure and performance was described using 1506 random data of structure-acute toxicity for mice (intravenously dosed). The structural patterns of the weakest toxic structures (111) were extracted from the data and the patterns discriminated for 64.2% of the other structures (1395). As for the 826 structures of strongest toxicity, 78.3% were discriminated by these structural patterns. These results were obtained by using structural parameter ratios to describe the structural patterns and the exhaustive elimination process to select the best parameter ratio from many candidates. The results were summarized in the form of a chart which can be used for practical screening for the weakest toxic structures.     

质量控制图用于石墨炉原子吸收光谱法检测海水中铅元素

为保证海水中重金属检测结果的准确可靠,以铅元素为例,每个工作日使用石墨炉原子吸收光谱仪平行测定铅质控样2次,收集20组有效数据后,通过计算均值、标准差得出上下控制限、警告线及辅助限,绘制出在当前实验室环境条件、仪器设备、试剂药品和人员水平等因素条件下的质量控制图。该质量控制图不仅用于实际检测过程中对检测结果进行监控,还可为该实验室的人员考核、留样复测等实验室质量控制行为提供结果判定依据。     

Metal foams: A survey

The current state-of-the-art in the development of cellular metal foams is reviewed, with focus on their fabrication, mechanical/thermal/acoustic properties, and potential applications as lightweight panels, energy absorbers, heat exchangers, and acoustic liners. Foam property charts with scaling relations are presented, allowing scoping and selection through the use of material indices.     

ANN技术在企业经济预测与预警中的应用研究

提出了适合于上市公司而建立的基于ANN技术的企业经济综合指标短期预警系统的构建方案.该系统是一个人机相结合的反馈式预警系统,包括危机判定、财务指标预测、预警知识获取和报警四个子系统.该系统将定性分析与定量分析结合起来,既突出人的作用,又充分发挥了人工神经网络的在预测方面的技术,使得两者有机的结合在一起.其中,预警指标预测子系统体现了ANN技术在时间序列预测方面的应用,而知识获取子系统和报警子系统则体现了ANN技术在回归预测方面的应用,两者都有很好的理论基础.同时,该系统建立的程序比较规范,具有普适性,易于操作,比较容易实现.最后,还对该系统进行了实证模拟分析,并与专家意见结果进行了对比,验证了其有效性.     

基于SARIMA-BP神经网络组合方法的MODIS叶面积指数时间序列建模与预测

植被叶面积指数(LAI)时间序列的建模及预测是陆面过程模型和遥感数据同化方法的重要组成部分。MODIS数据产品MOD15A2是目前应用最为广泛的LAI数据源之一,然而MODIS LAI时间序列产品包含了一些低质量的数据,例如由于云层、气溶胶等的影响,该产品在时间和空间上缺乏连续性。MODIS LAI时间序列包含线性部分和外在干扰产生的非线性部分,单一的线性方法或非线性方法都不能对其精确建模和预测。首先利用Savitzky-Golay(SG)滤波和线性插值平滑受到干扰的LAI时间序列,然后采用季节自回归积分滑动平均(SARIMA)方法、BP神经网络方法及二者的组合方法(SARIMA-BP)对MODIS LAI时间序列进行建模及预测。在SARIMA-BP神经网络组合方法中,各自在线性与非线性建模的优势得以充分发挥,其中SARIMA方法用于建模及预测LAI时间序列中的线性部分,BP神经网络方法用于对非线性残差部分进行建模及预测。实验结果显示：SG滤波和线性插值后的LAI时间序列比原LAI时间序列更平滑;SARIMA-BP神经网络组合方法的决定系数为0.981,比SARIMA和BP神经网络的0.941和0.884更接近于1;SARIMA-BP神经网络组合方法的预测值同观测值之间的相关系数为0.991,高于SARIMA(0.971)和BP神经网络(0.942)的相关系数。由此得出结论：SARIMA-BP神经网络组合方法对MODIS LAI时间序列具有更好的适应性,其建模和预测准确性高于SARIMA方法或BP神经网络方法。     

Finite element and sensitivity analysis of thermally induced flow instabilities

This paper presents a finite element algorithm for the simulation of thermo‐hydrodynamic instabilities causing manufacturing defects in injection molding of plastic and metal powder. Mold‐filling parameters determine the flow pattern during filling, which in turn influences the quality of the final part. Insufficiently, well‐controlled operating conditions may generate inhomogeneities, empty spaces or unusable parts. An understanding of the flow behavior will enable manufacturers to reduce or even eliminate defects and improve their competitiveness. This work presents a rigorous study using numerical simulation and sensitivity analysis. The problem is modeled by the Navier–Stokes equations, the energy equation and a generalized Newtonian viscosity model. The solution algorithm is applied to a simple flow in a symmetrical gate geometry. This problem exhibits both symmetrical and non‐symmetrical solutions depending on the values taken by flow parameters. Under particular combinations of operating conditions, the flow was stable and symmetric, while some other combinations leading to large thermally induced viscosity gradients produce unstable and asymmetric flow. Based on the numerical results, a stability chart of the flow was established, identifying the boundaries between regions of stable and unstable flow in terms of the Graetz number (ratio of thermal conduction time to the convection time scale) and B, a dimensionless ratio indicating the sensitivity of viscosity to temperature changes. Sensitivities with respect to flow parameters are then computed using the continuous sensitivity equations method. We demonstrate that sensitivities are able to detect the transition between the stable and unstable flow regimes and correctly indicate how parameters should change in order to increase the stability of the flow. Copyright © 2009 John Wiley & Sons, Ltd.     

基于主成分的改进雷达图及其在综合评价中的应用

本文从可视化角度出发,在总结传统可视化方法因优点与不足的基础上,将主成分分析、因子分析与雷达图结合,改进了传统的可视化方法。并将新的可视化方法引入到综合评价中,提出了一种基于雷达图面积的综合评价模型,实例验证该种方法切实有效。     

图与抽样资源的有效分配

研究了正态分布下(?)图与抽样资源分配方式之间的关系。结果表明高抽样率并不是控制图高效的必要条件,其效率还大大依赖于抽样资源分配方式。基于统计性质和平均质量损失,不管是控制图的初始表现,稳态表现还是优化结果,均显示在抽样率固定下,要想快速发现过程均值大的飘移量或期望值大的随机飘移量,应该频繁采集小容量的样本;而对于过程均值小的飘移量或期望值小的随机飘移量,高效方式为在大抽样间隔下采集大容量样本。