Recent progress on equation-oriented optimization of complex chemical processes

Process optimization in equation-oriented (EO) modeling environments favors the gradient-based opti-mization algorithms by their abilities to provide accurate Jacobian matrices via automatic or symbolic differentiation.However,computational inefficiencies including that in initial-point-finding for Newton type methods have significantly limited its application.Recently,progress has been made in using a pseudo-transient (PT) modeling method to address these difficulties,providing a fresh way for-ward in EO-based optimization.Nevertheless,research in this area remains open,and challenges need to be addressed.Therefore,understanding the state-of-the-art research on the PT method,its principle,and the strategies in composing effective methodologies using the PT modeling method is necessary for further developing EO-based methods for process optimization.For this purpose,the basic concepts for the PT modeling and the optimization framework based on the PT model are reviewed in this paper.Several typical applications,e.g.,complex distillation processes,cryogenic processes,and optimizations under uncertainty,are presented as well.Finally,we identify several main challenges and give prospects for the development of the PT based optimization methods.     

Inhabiting Time

In recent architecture, design has prioritised an engagement with time through its creation of temporary and highly flexible structures. There has, however, been less focus on how the design of buildings might impact the experience of time of the people who inhabit them. Here the distinguished author and emeritus professor Juhani Pallasmaa , who is renowned for his writings on the phenomenology of architecture, provides a reminder of the importance of what it means to ‘dwell in time’.     

Structure of insoluble complex formed by a block copolymer of 2-ethyl-2-oxazoline and ethylene oxide and poly(methacrylic acid)

Complexes that were insoluble in water were formed by mixing aqueous solutions of a block copolymer of 2-ethtyl-2-oxazoline (EOX) and ethylene oxide (EO) and those of poly(methacrylic acid) (PMAA). The structures of these complexes were investigated by the results obtained mainly by infrared spectroscopy, X-ray diffraction, and differential scanning calorimetry. The molar ratio of MAA in the complexes was also estimated by analyzing the infrared spectra. Whereas homopolymers of EOX and EO formed nearly equimolar complexes with PMAA irrespective of the feed molar ratio, the molar ratio of MAA in the complexes formed by the block copolymer and PMAA depended on the feed molar ratio. Although the infrared spectra indicated structural differences between the homopolymer of EOX and EOX in the block copolymer before forming complexes, the spectra obtained for the complexes formed by the homopolymer and the block copolymer were similar to each other.     

Evaluation of the complex material constants of piezoelectric ceramics in the thickness vibration mode

A new noniterative method, for determining the dielectric, piezoelectric and elastic constants, in complex form, for piezoceramic materials, in the thickness extensional mode, was proposed.This method is very flexible, as it is based on the standard approach to determine the elastic stiffness, followed by the measurement of the impedance at two frequencies to calculate the dielectric and piezoelectric constants, by solving a system of two equations.The new method was tested on materials with various thickness coupling factors (k_t = 4.5–60%) and mechanical quality factors (Q_mt = 20–1600), proving very good accuracy for all of them.The accuracy of standard method was also evaluated for the same materials.     

复杂曲面快轴伺服加工技术

采用一种直线滚动导轨式快轴伺服系统对典型复杂曲面进行加工。介绍快轴试验样机结构和快轴控制系统控制算法。根据快轴伺服装置的简化模型求得快轴试验样机数学模型。分析快轴伺服系统控制模型,建立快轴伺服系统动刚度数学模型。通过理论仿真和实验研究系统控制参数对动刚度的影响规律,并对提高伺服动刚度后的快轴伺服系统进行性能测试。对典型复杂曲面进行快轴切削实验,验证了该快轴伺服系统加工复杂曲面的精度较高。     

长洲水利枢纽水情自动测报系统方案设计

阐述长洲水利枢纽水情自动测报系统建设的意义及要求,结合流域的实际情况和特点,确定总体方案和系统覆盖范围,论证建设规模和遥测站网的布设,分析预报方案配置,并合理选择工作体制和通信组网方式。     

广西长洲贯流式机组发导瓦支撑厚度修正方法探讨

文章简要介绍了广西长洲水利枢纽大型灯泡贯流式水轮发电机组发电机分块导轴瓦温差产生的原因并提出了解决方法,通过对导轴瓦支撑块厚度进行修正,发导瓦温及温差均有了明显降低,达到了预期目的。     

长洲水利枢纽工程1号船闸下闸首叠梁门的设计体会

大跨度叠梁门作为闸门的一种特殊类型,具有重量重、跨度大等鲜明的特点,笔者结合长洲水利枢纽工程1号船闸下闸首叠梁门的设计,从闸门面板厚度的选择、闸门主梁的布置、闸门启门力的计算等方面对大跨度叠梁门的设计进行探讨和总结,可为以后的大跨度叠梁门的设计提供参考。     

长洲水利枢纽截流试验与现场实施

长洲水利枢纽坝址区的两个江心岛泗化洲岛和长洲岛将浔江隔成三江,对任何一江截流,其他两江的流量过程均是非恒定的。这种非恒定流过程对截流时通航水流条件和截流龙口水流条件均产生了进一步的恶化,较大地增加了截流难度。截流试验研究所阐述的现象和问题,在实际截流时得到了较好的再现;所给出的解决方案和工程措施,有效地保证了实际截流工作的顺利完成。     

那吉航运枢纽2~#机组主轴内轮毂油管脱落事故分析

介绍了那吉航运枢纽2#机组因主轴腔内的轮毂油管脱落而引起的事故经过,经检查确认事故原因为轮毂油管螺纹连接处的止动块断裂导致轮毂油管脱落。对止动块断裂的原因进行了分析,并介绍了事故损坏设备的修复措施。