Optimization and statistical analysis of Au-ZnO/Al2O3 catalyst for CO oxidation

In our former work [Catal. Today 174 (2011) 127], 12 heterogeneous catalysts were screened for CO oxidation, and Au-ZnO/Al₂O₃ was chosen and optimized in terms of weight loadings of Au and ZnO. The present study follows on to consider the impact of process parameters (catalyst preparation and reaction conditions), in conjunction with catalyst composition (weight loadings of Au and ZnO, and the total weight of the catalyst), as the optimization of the process parameters simultaneously optimized the catalyst composition. The optimization target is the reactivity of this important reaction. These factors were first optimized using response surface methodology (RSM) with 25 experiments, to obtain the optimum: 100 mg of 1.0%Au-4.1%ZnO/Al₂O₃ catalyst with 220 °C calcination and 100 °C reduction. After optimization, the main effects and interactions of these five factors were studied using statistical sensitivity analysis (SA). Certain observations from SA were verified by reaction mechanism, reactivity test and/or characterization techniques, while others need further investigation.     

Effects of the method of identification of the diffusion coefficient on accuracy of modeling bound water transfer in wood

An alternative approach to determining the bound water diffusion coefficient is proposed. It comprises a method for solving the inverse diffusion problem, an improved algorithm for the bound-constrained optimization as well as an alternative submodel for the diffusion coefficient’s dependency on the bound water content. Identification of the diffusion coefficient for Scots pine wood (Pinus sylvestris L.) using the proposed inverse approach is presented. The accuracy of predicting the diffusion process with the use of the coefficient values determined by traditional sorption methods as well as by the inverse modeling approach is quantified. The similarity approach is used and the local and global relative errors are calculated. The results show that the inverse method provides valuable data on the bound water diffusion coefficient as well as on the boundary condition. The results of the identification can significantly improve the accuracy of mass transfer modeling as studied for drying processes in wood.     

有阻尼质量弹簧系统逆特征值问题的一种解法

本文探讨了用附加已知质量的方法求解有阻尼质量弹簧系统逆特征值问题的可能性。它意味着可以从测得的复频率信息中淬取出系统的结构(物理)参数。而系统的复频率的获得只需在结构上布置一个测点。     

CHARACTERISTICS OF CLAY MINERALS IN ASIAN DUST AND THEIR ENVIRONMENTAL SIGNIFICANCE

The objectives of this research were to characterise the clay minerals composition of soil-derived dust in Northern China and to set up a mineralogical signature to trace their origin. Mineral composition of aerosol particles was investigated at Aksu, Dunhuang, Yulin, Tongliao and Changwu during an intensive field campaign period of ACE-Asia. The results show that the kaolinite （K） to chlorite （C） ratio is sensitive to the regional origin of Asian dust. Western source areas （represented by Aksu） displayed the lowest K/C ratio of 0.3 （average）, while it was found to increase up to 0.70 （average） upon moving towards northern source areas （represented by Yulin）. By studying transported dust in a deposition area representative of the Chinese Loess Plateau, the usefulness of the K/C ratio, when associated with back air-mass trajectories, was found to lie in revealing the origin of the dust. Comparison of the mineralogical data between Asian dust and Sahara dust, shows that the K/C ratio is also an effective signature to identify the source areas on a hemisphere scale.     

On the identification of non-linear mechanical systems using orthogonal functions

Real world mechanical systems present non-linear behavior and in many cases simple linearization in modeling the system would not lead to satisfactory results. Coulomb damping and cubic stiffness are typical examples of system parameters currently used in non-linear models of mechanical systems. This paper uses orthogonal functions to represent input and output signals. These functions are easily integrated by using a so-called operational matrix of integration. Consequently, it is possible to transform the non-linear differential equations of motion into algebraic equations. After mathematical manipulation the unknown linear and non-linear parameters are determined. Numerical simulations, involving single and two degree-of-freedom mechanical systems, confirm the efficiency of the above methodology.     

Modélisation du comportement thermique d'un outil de fraisage : approche par identification de système non entierThermal modelling of a milling tool: a noninteger system identification approach

In this work we present an experimental apparatus devoted to the thermal characterisation of a milling tool. The experimental device used thermistors, one for each insert. Each thermistor is located at a point in the tool close to the tip of the insert. The heat flux in each insert is expressed according to the temperature at the sensor from a non-integer model. The parameters of the model are identified from transient evolutions measurements of the temperature on the sensor and on the cutting edge. An application shows the difference in the behaviour of each insert during machining from the estimated heat fluxes. To cite this article: J.-L. Battaglia et al., C. R. Mecanique 330 (2002) 857–864.     

组合结构结合部动态参数的实验识别方法

根据两种不同的试验情况，提出了相应的利用实测传递函数识别组合结构结合部刚度、阻尼参数的方法，给出了识别过程的数学原理，该方法避免了对实测传递函数矩阵求逆运算，有效地防止了测试误差在识别过程的扩大化，计算机仿真试验表明，本文方法数值计算稳定，识别效果良好。     

惯导平台陀螺安装误差角辨识的制约因素分析及对策

在惯导平台多位置静态测漂方案下,对陀螺安装误差角的辨识结果往往很不理想。本文通过分析陀螺误差角影响惯导平台漂移的机理,发现平台壳体的角速率是制约误差角辨识精度的主要因素。由此,在测漂过程中有针对性地引入了转台相对地面的角,速率。仿真结果显示,转台角速率的引入能使陀螺安装误差角的辨识精度得到明显的提高。     

基于粗集—神经网络的磨粒模式识别

应用粗集理论中最小约简的近似算法 ,对磨粒的形状参数进行约简 ,找出判断磨粒模式的形状参数长短轴比 Rt和圆度 Rd,同时采用这些参数训练神经网络以进行磨粒模式识别 .结果表明 :应用此算法 ,对 63个已知样本和历时 2年多对柴油机 1 4 5个润滑油油样进行制谱分析判断 ,准确率在 90 %以上 ,比原来用模糊识别的准确率提高了约 1 0个百分点 ;使用 BP网络减化了网络结构 ,使网络的训练速度加快 ,整个系统变得简单、可靠、有效     

振动频谱再分析的模糊模式识别法

本文首先讨论工程振动信号频谱再分析技术,针对所存在问题,提出模糊式识别再分析方法,以滚动轴承振动成因研究中的谱分析为例,具体介绍了频谱的峰值频率分布模式,模糊子集及隶属函数的确定,以及综合评判的识别过程,最后给出一具体计算结果。