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为了探究夹芯注射成型塑件厚度对芯层物料分布的影响,分别选取聚丙烯(PP)/PP,PP/低密度聚乙烯(PE-LD)两种物料组合,对一组不同厚度的夹芯注射成型塑件进行了模流分析,表征、测试和分析了芯层物料穿透深度、平均相对厚度、分布均匀度的变化规律。研究结果表明,塑件厚度由5 mm增大到10 mm时,两种物料组合对应的评价指标变化趋势相同,芯层物料穿透深度减小、平均相对厚度增大、分布均匀度变差;PP/PE-LD物料组合较PP/PP物料组合对应的评价指标变化趋势更为明显,前者芯层物料穿透深度、平均相对厚度、平均相对厚度标准差的极差值较后者分别提升了112.71%,134.82%,108.16%;塑件厚度变化时,熔体沿各向流动阻力差异性、芯/壳层熔体黏度比均发生变化,但PP/PE-LD物料组合中芯/壳层熔体黏度比变化显著,而PP/PP物料组合中芯/壳层熔体黏度比则相对稳定。 相似文献
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夹芯注射成型研究进展 总被引:1,自引:0,他引:1
为了了解夹芯注射的成型过程及内部结构、探悉其成型机理,研究者主要对芯层熔体前缘的冲破现象、芯壳层物料的分布情况以及夹芯注塑件的力学性能进行了研究。文献显示,物料的性能尤其是粘度、加工工艺参数如注射速度、模温、熔融温度等以及模具尺寸对夹芯注射的充模过程及其制品最终的性能影响最为突出。 相似文献
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调整芯、壳层熔体的注射温度、速率均可降低夹芯注射成型中芯层熔体冲破趋势.利用Moldflow软件的coinjection模块和正交实验法,分析评价如何调整熔体的注射温度和速率可以最有效地降低芯层熔体冲破趋势.实验发现,芯层熔体冲破趋势对芯/壳层熔体黏度比(R)极敏感,通过减小芯层熔体注射温度、增大壳层熔体注射温度或增大壳层熔体注射速率,均可显著降低芯层熔体冲破趋势,且熔体注射温度的影响更为显著;选取的芯、壳层物料假塑性不同,芯层熔体注射速率对芯层熔体冲破趋势的影响效果不同,甚至相反. 相似文献
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本文详细分析了传统的夹芯注射成型工艺后指出,原工艺过程可大大简化。方法是把原来采用两个机筒分别制备、分别注射两种物料(二步法)改为在一个机筒内制备、一次注射成型(一步法)。一步法工艺简单实用,可用于再生料的加工,而设备改造所需投资却很少。 相似文献
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基于BP神经网络的水泥抗压强度预测研究 总被引:11,自引:1,他引:10
探讨应用BP(back-propagation)神经网络进行经28d抗压强度预测的方法。利用BP网络很强的非线性映射功能,建立抗压强度相关因素与抗压强度之间的关系。通过对样本的学习,BP网络将这种非线性映射关系以分布并行的方式存储在网络的联结权矩阵中,从而达到对样本集的非逻辑归纳。本文提出了强度预测模型能够以较高的精度预测水泥28d抗压强度。作为对比,同时应用回归分析方法预测水泥28d抗压强度,两 相似文献
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l 弓 言 对大型回转机械故障的诊断与监测,目前国内外均投入了大量的人力和物力。但是,匕经研制出来的专家系统存在很多缺陷,如知识获取困难,系统缺少动态或在线学习能力。化工行业中机器的动态变化大,监测参数多,运行环境变化频繁。神经网络具有很强的跟踪性,文献[fi讨论了人工神经网络用于故障诊断的优越性。目前,人们已经利用神经网络解决了化工炼油厂中的一些典型问题[”]:动态模型的建立、化工系统的过程控制、预报和传感器的故障诊断。本文将神经网络应用于化工过程中的大型回转机械运行状态的监测。 2 物理对象的描述 设不同时刻获取… 相似文献
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T. Ttayagarajan M. Ponnavaikko J. Shanmugam R.C. Panda PG. Rao 《Drying Technology》2013,31(6):931-966
Abstract This paper reviews the developments in the model based control of drying systems using Artificial Neural Networks (ANNs). Survey of current research works reveals the growing interest in the application of ANN in modeling and control of non-linear, dynamic and time-variant systems. Over 115 articles published in this area are reviewed. All landmark papers are systematically classified in chronological order, in three distinct categories; namely, conventional feedback controllers, model based controllers using conventional methods and model based controllers using ANN for drying process. The principles of ANN are presented in detail. The problems and issues of the drying system and the features of various ANN models are dealt with upto-date. ANN based controllers lead to smoother controller outputs, which would increase actuator life. The paper concludes with suggestions for improving the existing modeling techniques as applied to predicting the performance characteristics of dryers. The hybridization techniques, namely, neural with fuzzy logic and genetic algorithms, presented, provide, directions for pursuing further research for the implementation of appropriate control strategies. The authors opine that the information presented here would be highly beneficial for pursuing research in modeling and control of drying process using ANN 相似文献
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ARTIFICIAL NEURAL NETWORKS: PRINCIPLE AND APPLICATION TO MODEL BASED CONTROL OF DRYING SYSTEMS - A REVIEW 总被引:1,自引:0,他引:1
T. Ttayagarajan M. Ponnavaikko J. Shanmugam R.C. Panda PG. Rao 《Drying Technology》1998,16(6):931-966
This paper reviews the developments in the model based control of drying systems using Artificial Neural Networks (ANNs). Survey of current research works reveals the growing interest in the application of ANN in modeling and control of non-linear, dynamic and time-variant systems. Over 115 articles published in this area are reviewed. All landmark papers are systematically classified in chronological order, in three distinct categories; namely, conventional feedback controllers, model based controllers using conventional methods and model based controllers using ANN for drying process. The principles of ANN are presented in detail. The problems and issues of the drying system and the features of various ANN models are dealt with upto-date. ANN based controllers lead to smoother controller outputs, which would increase actuator life. The paper concludes with suggestions for improving the existing modeling techniques as applied to predicting the performance characteristics of dryers. The hybridization techniques, namely, neural with fuzzy logic and genetic algorithms, presented, provide, directions for pursuing further research for the implementation of appropriate control strategies. The authors opine that the information presented here would be highly beneficial for pursuing research in modeling and control of drying process using ANN 相似文献
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基于径向基神经网络的聚丙烯熔融指数预报 总被引:13,自引:7,他引:6
引 言在化工生产中大部分生产流程具有非线性、大时滞、结构复杂等特性 ,而且生产变量之间存在着不同程度的耦合与关联 .前馈神经网络由于具有强大的拟合非线性函数的能力 ,已成为生产指标预测的有力工具[1] .其中径向基 (radialbasisfunction ,RBF)神经网络相对于神经网络BP 相似文献
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In this work we focus on the synergy between modeling with RNNs, and nonlinear controller design for decoupling control. The thesis of the paper is that recurrent neural networks (RNNs) can be conveniently used in an integrated black-box modeling and controller design methodology for decoupling control of multivariable nonlinear systems. A simulation example on a multivariable continuous-stirred-tank-reactor (CSTR) is provided to elucidate related issues. The effects of modeling uncertainty and state reconstruction on decoupling performance are specifically discussed. 相似文献
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用人工神经网络预测混杂复合材料混杂效应 总被引:1,自引:0,他引:1
本研究建立一个二输入单输出的BP人工神经网络模型,并用QBASIC语言编制了相应的软件。利用该神经网络模型对混杂效应与混杂比及分散度系数间关系进行了预测。研究结果表明,网络经过61223次的迭代,预潮值误差为0.12%,具有很高的预测精度,可用于混杂复合材料混杂效应的预测。 相似文献