On the selection of variables for qualitative modelling of dynamical systems

Behavioural modelling of physical systems from observations of their input/output behaviour is an important task in engineering. Such models are needed for fault monitoring as well as intelligent control of these systems. The paper addresses one subtask of behavioural modelling, namely the selection of input variables to be used in predicting the behaviour of an output variable. A technique that is well suited for qualitative behavioural modelling and simulation of physical systems is Fuzzy Inductive Reasoning (FIR), a methodology based on General System Theory. Yet, the FIR modelling methodology is of exponential computational complexity, and therefore, it may be useful to consider other approaches as booster techniques for FIR. Different variable selection algorithms: the method of the unreconstructed variance for the best reconstruction, methods based on regression coefficients (OLS, PCR and PLS) and other methods as Multiple Correlation Coefficients (MCC), Principal Components Analysis (PCA) and Cluster analysis are discussed and compared to each other for use in predicting the behaviour of a steam generator. The different variable selection algorithms previously named are then used as booster techniques for FIR. Some of the used linear techniques have been found to be non-effective in the task of selecting variables in order to compute a posterior FIR model. Methods based on clustering seem particularly well suited for pre-selecting subsets of variables to be used in a FIR modelling and simulation effort.     

矿山尾砂胶结充填工程过程检测的常见问题

基于胶结充填工艺,就关键设备与过程参数检测,列出设计与实施中经常会存在的一些问题,并给出解决的方法。     

一种不可压缩流体控制阀口径计算公式的应用

本论文针对渤海某海上采油平台控制阀的实际应用情况,结合目前控制阀的行业标准,讨论了控制阀选型原则和不可压缩流体阀门计算公式的应用。最后给出了控制阀参数选取及手工计算的实例并利用InstruCalc软件进行验算。     

Drying in the Context of the Overall Process

Abstract

Although drying has traditionally been considered as a unit operation, it is strongly affected by upstream operations such as crystallization and solid–liquid separation, and in turn can affect downstream processes such as gas cleaning and micronization. Process design needs to consider the complete flowsheet and the interactions between the different steps as early as possible. Key points are the particle formation method and the final product specification. The mean particle diameter and particle size distribution are vital parameters throughout the process, as smaller particles and fines make solids handling, dewatering, and washing more difficult. This in turn affects the inlet moisture content to the dryer, and hence the heat duty and performance. Intermediate size enlargement or reduction may be used to give a more easily dried particle or agglomerate. There are important links to the new subject of product engineering, for example in the choice of processing route to achieve a given product quality and specification. The interactions between the different process steps can affect process design, equipment selection and troubleshooting, and this is illustrated by industrial case studies. A holistic approach is proposed to allow the whole solids processing flowsheet to be optimized as an entity, rather than optimising each unit operation in isolation and then finding a conflict between them.     

A new data mining approach to estimate causal effects of policy interventions

This paper presents a data driven approach that enables one to obtain a measure of comparability between-groups in the presence of observational data.The main idea lies in the use of the general framework of conditional multiple correspondences analysis as a tool for investigating the dependence relationship between a set of observable categorical covariates X and an assignment-to-treatment indicator variable T, in order to obtain a global measure of comparability between-groups according to their dependence structure. Then, we propose a strategy that enables one to find treatment groups, directly comparable with respect to pre-treatment characteristics, on which estimate local causal effects.     

磁悬浮拉幅定型传送单元滑动块材质优选

针对机械摩擦多、噪声大的传统拉幅定型传送单元,提出一种新型的磁悬浮拉幅定型传送单元。磁悬浮拉幅定型传送单元作为新型的纺织机械传送单元,具有无机械摩擦、无噪声、污染少等优点。对新型传送单元滑动块材料进行选择,对比3种金属材料灰口铸铁、45号钢、Q235碳素结构钢。使用ANSYS分析电磁铁磁力在不同间隙下的变化,再利用ANSYS Workbench分析不同磁力下,3种材料传送单元滑动块的变形情况,判断其对传送单元悬浮气隙的影响。分析结果表明:悬浮气隙在0.005 mm以内,磁力误差在5%以内;Q235碳素结构钢比其余两种材料更适合做滑动块,并且降低了成本。     

新型织造设备选型及使用情况评估

通过收集有关技术指标数据，采用曲线求积法，比较各种织机指标差异，求得其封闭曲线的面积，找出理想的机型；通过比较新型织造设备的使用水平与理想水平的差异，分析评估新型织造设备的使用情况，说明：曲线求积法可作为设备选型和使用情况评估以及进一步用好、管好设备的一种简单而有效的方法。     

On the equivalence of Kernel Fisher discriminant analysis and Kernel Quadratic Programming Feature Selection

We reformulate the Quadratic Programming Feature Selection (QPFS) method in a Kernel space to obtain a vector which maximizes the quadratic objective function of QPFS. We demonstrate that the vector obtained by Kernel Quadratic Programming Feature Selection is equivalent to the Kernel Fisher vector and, therefore, a new interpretation of the Kernel Fisher discriminant analysis is given which provides some computational advantages for highly unbalanced datasets.     

Batch Grinding in Laboratory Ball Mills: Selection Function

The selection functions and the breakage distribution functions are based on the experimentally‐determined particle size distribution on the basis of comminution of one size fraction particles. Therefore, to obtain a clear picture of the product properties during comminution of the “real” polydisperse sample, a number of experiments are needed. This work introduces the tested methodology for the selection function determination based on the starting and maximal values of the selection function. The principle was tested on the planetary ball mill and the horizontal laboratory ball mill, and according to the results obtained, it can be concluded that the proposed methodology can be useful for the evaluation of the selection function during batch comminution in different mills.     

A Critical Assessment of Industrial Coal Drying Technologies: Role of Energy,Emissions, Risk and Sustainability

Low-rank coals (LRCs) constitute about 45% of the total coal reserves and hence will soon be the fossil fuel of choice in many countries despite their high moisture content on mining, which varies from 30% to as high as 66%. It is important to reduce their water content to enhance the heating value and reduce transportation costs while enhancing combustion efficiency, safety, and reduction of emissions on combustion. The level of moisture to be achieved upon drying LRCs depends on the end application; it varies from as low as 0% for hydrogenation processes to 15% for briquetting and gasification processes. Numerous drying technologies have been proposed for drying coal; they include pulse combustion, vacuum, fluid bed, rotary, flash, microwave, and superheated steam drying. Each technology has some pros and cons, which are not always clearly spelled out in the literature. In addition, it is necessary to develop sustainable rather than just cost-effective drying systems for LRC. In this article we assess various coal drying techniques critically and identify their strengths and weaknesses. Some theoretical comparisons of different dryer types are carried out based on energy utilization and carbon footprints. The jury is still out on optimal drying technology for LRC and innovative design concepts should be evaluated before finalizing the selection.