THERMAL DYNAMICS OF A DRUM DRYER

The thermal dynamics of a top-loading drum dryer is studied with a view of deriving the transfer function for the thermal process involved. The drum which initially operates at a steady state, is subjected to a step change in the steam pressure and the response of the temperature of the outer surface of the drum is recorded. The normalised time domain response of the temperature T is analysed using the least squares method to a non-linear function. The time domain response is also transformed into the frequency domain using Fourier transforms and the transfer function is derived.     

两种阶跃响应辨识算法的应用对比与实现

以系统阶跃响应测试数据为依据,针对存在滞后对象的传递函数模型,在开环状态下引入两种使用最小二乘法实现的辨识方法。同时,利用两种算法对不同的控制对象进行模型辨识,验证了两种辨识方法具有较高的辨识精度及方法的可行性,为工业应用提供了有力的理论依据。     

基于继电反馈的辨识的研究

详细论述继电反馈技术在模型辨识中的应用,阐述各种继电反馈辨识方法的原理与优缺点。在此基础上,分析继电反馈辨识技术今后可能的发展方向。     

Fault identification for process monitoring using kernel principal component analysis

In this research, we develop a new fault identification method for kernel principal component analysis (kernel PCA). Although it has been proved that kernel PCA is superior to linear PCA for fault detection, the fault identification method theoretically derived from the kernel PCA has not been found anywhere. Using the gradient of kernel function, we define two new statistics which represent the contribution of each variable to the monitoring statistics, Hotelling's T²and squared prediction error (SPE) of kernel PCA, respectively. The proposed statistics which have similar concept to contributions in linear PCA are directly derived from the mathematical formulation of kernel PCA and thus they are straightforward to understand. The main contribution of this work is that we firstly suggest a fault identification method especially applicable to process monitoring using kernel PCA. To demonstrate the performance, the proposed method is applied to two simulated processes, one is a simple nonlinear process and the other is a non-isothermal CSTR process. The simulation results show that the proposed method effectively identifies the source of various types of faults.     

An arrangement of ideal zones with shifting boundaries as a way to model mixing processes in unsteady stirring conditions in agitated vessels

This paper investigates the way modelling mixing phenomena occur in unsteady stirring conditions in agitated vessels. In particular, a new model of torus reactor including a well-mixed zone and a transport zone is proposed. The originality of the arrangement of ideal reactors developed here lies in the time-dependent location of the boundaries between the two zones. This concept is applied to model the positive influence of unsteady stirring conditions on homogenization process: the model avoids a mass balance discontinuity when the transition from steady to unsteady stirring conditions is performed.To ascertain the reliability of the model proposed, experimental runs with highly viscous fluids have been carried out in an agitated tank. The impeller used was a non-standard helical ribbon impeller, fitted with an anchor at the bottom. The degree of homogeneity in the tank was observed using a conductivity method after a tracer injection.It is shown that for a given agitated fluid and mixing system, model parameters are easy to estimate and that modelling results are in close agreement with experimental ones. Moreover, it would appear that this model allows the easy derivation of a control law, which is a great advantage when optimizing the dynamics of a mixing process.     

非线性系统的参数空间边界辨识与系统结构故障检测

本文利用矩形窗最小二乘估计构造了非线性系统的参数空间边界辨识方法。参数边界辨识方法的分析表明，利用该方法辨识的参数值是样本状态邻域中非线性系统切空间的参数上下界，基于这种参数边界辨识方法，建立了一种系统结构突变故障检测器。并对二阶非线性系统进行的数字仿真得到了有效的边界参数估计和良好的故障检测结果。     

结构动态分析中边界刚度的识别

在结构的力学分析中,特别是结构的动态特性分析中,力学模型的边界条件是否能正确反映实际的边界状态是至关重要的。 本方法利用广义逆矩阵理论,识别出结构的边界刚度,给出了有关的公式。对一维和二维结构的试验表明,边界刚度的识别结果与实际相吻合,指出了在边界刚度处理上简单地附加弹簧的静态测试方法对结构的动态分析存在着不合理性。     

一株产低温脂肪酶酵母菌的鉴定及酶学性质

低温脂肪酶已成为工业低温工艺良好候选物,在生物质能源、食品、皮制品、废水处理等领域发挥重要作用。本文从实验室保藏的55株产低温脂肪酶酵母菌株中筛选出一株高产菌株NYNU 19160,通过形态学、生理生化以及ITS和26S rDNA序列分析,将该菌株鉴定为Papiliotrema fonsecae。经过硫酸铵分级沉淀、透析、浓缩将该脂肪酶纯化后,对酶学性质进行了研究。结果表明,该脂肪酶最适反应温度为20℃,最适作用pH为7.5,属于低温碱性脂肪酶;Cu²⁺显著促进该酶的水解活性,而Li⁺表现为显著抑制作用;有机溶剂乙腈、甲醇、乙酸对酶活性有较强的促进作用,而苯和正己烷则抑制了该酶的活性;该酶对对硝基苯酚丁酸脂(pNPC₄)底物表现出较强特异性。     

氯碱工业生产过程安全管理

介绍氯碱工业生产过程,分析生产中安全管理要点.指出企业应在多层安全防护设计理念指引下,从氯碱工艺本质安全性出发,加强对运行装置的有效管理;建立风险分级管控机制;重视检修作业过程监管,合理选择承包商;加强操作人员的业务技能培训;严格履行工艺变更程序;建立完善的事故应急处置体系,以确保氯碱装置的安全稳定运行.     

野生虫草无性型分离株分子鉴定及遗传多样性的研究

虫草具有较高的食用与药用价值,本文以19株野生虫草分离株为研究材料,利用ITS引物进行PCR扩增、测序,并从Genbank上下载虫草属相关序列,构建系统发育树,并对19株虫草无性型分离物进行ERIC-PCR扩增,同时还检测了上述无性分离物发酵液中虫草素的含量。系统发育分析表明在分子水平上19株虫草的无性型分离菌株,都为蛹虫草(Cordyceps militaris)。与高雄山虫草(C.takaomontana)、蝉花(C.cicadae)、古尼虫草(C.gunnii)以及冬虫夏草(C.sinensis)平均遗传距离分别为0.1269、0.1228、0.2251和0.2354,在遗传距离上,与高雄山虫草和蝉花较近,与冬虫夏草较远。ERIC-PCR相似系数在0.8水平上,可以将19个蛹虫草菌株分为3组,相似系数在0.9水平上19株蛹虫草菌种可以分为8组。对蛹虫草发酵液中虫草素含量检测发现,所有蛹虫草无性型分离物发酵液都含有虫草素,最高的可达到126.33 mg/L,为现有的蛹虫草生产菌株JD的119倍。