共查询到18条相似文献,搜索用时 62 毫秒
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提出了一种新的混合神经网络建模方法——结构逼近式混合神经网络。基于此结构建立的混合神经网络可以充分利用已知非线性系统的结构信息,使神经网络“灰盒”化,更好地解释和描述系统各变量间的因果关系,从而提高网络的建模精度和模型的可靠性。本文介绍了这类神经网络的基本特性、拓扑结构和训练方法。报告了一个典型放热液相二级平行间歇反应的建模过程;并针对间歇反应过程测量滞后的情况,与两种不同的混合神经网络模型作了比较,仿真和比较结果证明了方法的有效性。 相似文献
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基于结构逼近式神经网络的间歇反应器优化控制 总被引:2,自引:1,他引:1
利用结构逼近式混合神经网络(SAHNN)建立了一类典型放热液相二级平行间歇反应的数学模型。基于主产物浓度和反应温度的递归神经网络(RNN)模型,使用混合PSO-SQP算法求解该间歇反应主产物产率最大化问题,进而得到反应温度优化曲线。鉴于反应温度实时可测,提出扩展的EISE指标,该指标把实时计算的模型误差引入控制策略,为基于模型的控制增加了反馈通道,增强了控制方法的鲁棒性和抗干扰性能。利用 原理对所提出的一步超前预测控制做了稳定性分析,证明了算法的正确性。研究的结果充分证明了基于SAHNN混合神经网络模型的优化控制策略的有效性。 相似文献
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<正> 1 引言 微观混合是指流体分子尺度上的混合,而化学反应过程又是反应物分子间相互有碰撞作用的过程,微观混合对搅拌槽内进行化学反应有直接影响,因此开展对间歇搅拌反应器微观混合状况的研究十分必要。但微观混合的机理和模型较复杂,测定方法较困难,过去20年来集中于机理与模型研究,实际应用报道较少。本文对乙酸乙酯不可逆二级皂化间歇反应器中搅拌转速、介质粘度对微观混合状况的影响进行研究。 2 微观混合状态的描述 2.1 微观混合模型概述 从Danckwerts提出一整套混合统计概念和微观混合的2种极限理想状态后,许多研究者力求把这2种状态结合起来描述实际的微观混合状态,并通过大量实验,从工程和机理角度提出了不少微观混合模型。但这些工程模型都是单参数模型,经湍流类比分析,其微观混合参数都与理想混合时间有关,具有共同的结构特征。 相似文献
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鉴于煤直接液化反应的复杂性和机理模型难以建立、计算量大等,结合人工神经网络建模方法,建立了煤直接液化间歇反应器的BP神经网络模型,并利用统计极差分析方法考察了影响反应器煤转化率、油收率及综合评价3个指标的8个关键因素的敏感程度。结果表明,训练完成的BP神经网络模型不仅能很好地拟合已知实验结果,而且具有良好的预测能力,预测结果的平均相对误差为3.75%;当煤为烟煤或亚烟煤、溶剂分别为萘满(1,2,3,4-四氢化萘)或循环溶剂时,综合评价给出的影响因素的敏感性顺序为:温度>反应时间>剂煤比>煤粒度>氢分压和填充程度>煤类型>溶剂类型。 相似文献
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本文采用计算机模拟图解法和数值法确定间歇釜式反应器最佳反应时间,较传统的手工图解法更为直观、快速和准确,为反应器设计计算和教学提供了简捷有效的方法。 相似文献
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半间歇釜式反应器内物料积累过多且反应放热过快时,容易引发热失控风险,造成化工安全事故。设计较优的加料操作,既可以避免热失控风险,又可以缩短操作周期、提高生产效率。针对半间歇釜式反应器,以乙酸酐水解为模型反应,基于反应器数学模型,提出了一种安全高效加料操作的数值优化策略。在该策略中,首先确定不同加料方式(如一段、二段和三段加料)下的安全操作温度区间,然后在该温度区间内寻找最短操作周期对应的操作温度,该温度即为最佳的加料操作温度。优化结果表明三段加料的安全操作温度区间和最佳操作温度分别比一段加料宽60.9%和低1.9 K,六段加料已经基本可以实现操作周期最短,增加操作压力也有利于缩短操作周期。 相似文献
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介绍以对间歇反应器的一些基本合理的假设为基础,利用溶剂和传热介质的热力学和物性参数,推导出分别用水蒸汽和传热流体(THF)作为反应器夹套加热介质时,估算将反应器内料液进行脱溶浓缩所需时间的数学表达式,并用示例加以说明。 相似文献
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A simulation of a five-liter, agitated, nonisothermal, jet-assisted circulation, jacketed methylmethacrylate polymerization batch reactor considering all the available physical-chemical properties and related correlations for agitation and heat transfer coefficients is presented. From the calculated cumulative radical population, the phenomena of early runaway, thermal ignition and gel effect ignition are identified. Variations of medium viscosity over the course of the polymerization reaction affect the performance of the agitator and the overall heat transfer coefficient. The simulation results indicate that much higher heat duties can be removed by this special equipment design than in the case of a conventional vessel design. 相似文献
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Ana MRB Xavier Ana Paula M Tavares Margarida SM Agapito Dmitry V Evtuguin 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》2008,83(12):1602-1608
BACKGROUND: A sequential batch reactor (SBR) was used for eucalypt kraft pulp effluent treatment with Trametes versicolor. A 23 full factorial design and response surface methodology were applied to optimise the batch fermentation conditions. Effluent concentration, culture medium and inoculum age were the factors selected for this study in order to optimise the reduction of chemical oxygen demand (COD). RESULTS: The presence of Trametes Defined Medium (TDM) in the fermentation was required to obtain a significant COD reduction. Experiments in the batch reactor confirmed, in general, the predicted results of optimisation developed from Erlenmeyer batch assays. The T. versicolor culture remained active during 42 days of study in the SBR, providing approximately 80% of COD reduction. CONCLUSION: Trametes versicolor may be considered as very promising for the biological treatment of effluents from kraft pulp mills in an SBR system instead of the activated sludge mixed cultures traditionally used. Copyright © 2008 Society of Chemical Industry 相似文献
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研究了中试规模序批式膜生物反应器处理生活污水的特性.发现其对CODCr、NH3-N及TN的去除效果可分别达到95.0%、96.3%及38.0%;过膜阻力增加率为1.032 kPa8226;m-1.TN去除率偏低的主要原因在于缺少搅拌装置,在静置阶段时,污泥大部分沉积在反应器底部(系统运行期间30 min沉降比均低于40%),从而使反硝化细菌不能充分与水溶液中的NOx-N接触.采用空间排阻液相色谱法对混合液及膜污染物进行分子量分布测定,发现大量大分子物质在反应器内、膜面及膜孔内积累,相对分子质量大于104的有机物分别占64.0%、38.0%.经过物理及化学清洗,膜通量恢复了73.4%,多糖含量为清洗前的30.4%,说明多糖是造成不可逆污染的主要物质. 相似文献
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Gorazd Karer Igor krjanc Borut Zupan
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《Chemical Engineering and Processing: Process Intensification》2008,47(12):2379-2385
In this paper we study a self-adaptive predictive functional control algorithm as an approach to the control of the temperature in an exothermic batch reactor. The batch reactor is located in a pharmaceutical company in Slovenia and is used in the production of medicines. Due to mixed discrete and continuous inputs the reactor is considered as a hybrid system. The model of the reactor used for the simulation experiment is explained in the paper. Next, we assumed an exothermic chemical reaction that is carried out in the reactor core. The dynamics of the chemical reaction that comply with the Arrhenius relation have been well documented in the literature and are also summarized in the paper. In addition, the online recursive least-squares identification of the process parameters and the self-adaptive predictive functional control algorithm are thoroughly explained. We tested the proposed approach on the batch-reactor simulation example that included the exothermic chemical reaction kinetic model. The results suggest that such an implementation meets the control demands, despite the strongly exothermic nature of the chemical reaction. The reference is suitably tracked, which results in a shorter overall batch-time. In addition, there is no overshoot of the controlled variable T, which yields a higher-quality production. Finally, by introducing a suitable discrete switching logic in order to deal with the hybrid nature of the batch reactor, we were able to reduce the switching of the on/off valves to a minimum and therefore relieve the wear-out of the actuators as well as reduce the energy consumption needed for control. 相似文献
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厌氧序批式反应器(ASBR)是一种间歇运行的高速厌氧生物反应器,污泥颗粒化、非稳态运行和反应与沉淀集于一体等重要特征,为其高效的固液分离提供了条件.试验考察了ASBR反应器在MLSS为9.0~30g/L,进水OLR(COD)为=3~10g/(L·d),进水F/M(COD)为0.19~1.1g/(g·d)时,对其颗粒污泥沉降性能的影响因素.结果表明,ASBR表现出优良的沉降性能,影响污泥ZSV和SV、SVI的主要因素是MLSS,ZSV和SV、SVI对MLSS呈现出较好的相关性.而进水F/M与SV和ZSV、SVI之间无明显的变化规律. 相似文献