基于广义预测控制的间歇生产迭代优化控制

针对间歇生产,提出了一种基于广义预测控制的批次迭代优化控制策略--BGPC,在间歇过程中引入批次间优化的思想,将迭代学习控制ILC和广义预测控制GPC相结合,在GPC实时结构参数辨识的基础上利用前面批次的模型预测误差修正当前批次的模型预测值.该算法能够有效地克服模型失配、扰动和系统参数变化等情况.文章最后以一个数值例子和间歇反应器为对象进行仿真试验,验证了该算法是有效的.     

基于蚁群算法优化的再热汽温系统变参数预测PID控制

研究预测控制和PID控制在再热汽温系统控制中的应用.通过将神经网络作为预测模型,并用蚁群算法在线优化PID控制器参数.计算机仿真结果表明,基于蚁群算法的预测PID控制能够适应控制对象模型参数的时变,具有较好的鲁棒性,相对传统PID控制策略还表现出了良好的动态性能.     

基于广义预测控制策略的微生物燃料电池控制

针对MFC系统启动阶段输出响应不稳定以及调节时间较长的问题,结合微生物燃料电池自身特性,提出了基于广义预测控制(generalized predictive control,GPC)的微生物燃料电池(microbial fuel cell,MFC)控制策略。与加入PID控制方法对比得知,加入GPC的MFC系统输出能够避免响应出现大幅度的抖动,且响应速度快,动态调节鲁棒性好,保证了动态输出曲线快速准确地跟踪系统设定值。在给定外电阻为恒值和醋酸盐浓度随时间阶梯变化时,通过带遗忘因子的最小二乘法进行模型辨识,将所得线性模型作为预测模型,采用GPC算法进行控制。仿真表明,GPC能在控制响应速度方面取得好的控制效果以及系统调节过程中的鲁棒性也有了较大的改善。有效地实现了对微生物燃料电池系统的动态性能以及鲁棒性能的优化,验证了所提出的算法有效可行。     

基于改进型GPC算法的液位优化控制

以双容水箱为被控对象,利用MATLAB/Simulink程序开发工具,对广义预测控制(GPC)进行仿真和实验研究。首先建立一个控制系统的数学模型,然后对GPC算法进行选择,最后对应用广义预测控制算法的模型进行了仿真验证。实验结果表明:所提出的算法具有良好的动态响应性能,可快速跟踪设定值,得到了较好的控制效果。     

基于Matlab的吹膜机薄膜张力控制系统的建模与仿真

提出一种包含压缩因子及模拟退火算子的改进型粒子群算法,弥补了常规PSO算法的缺点。同时,提出一种改进型的二自由度PID控制器,并用改进的二自由度PID控制器替换薄膜张力控制系统中的常规PID控制器。仿真结果表明:改进方法具有优良的控制效果及鲁棒性,可以更好地满足吹膜机塑料薄膜张力控制系统参数复杂多变的生产环境。     

基于模糊PID算法的自动控制研究

针对溶解氧浓度控制存在响应速度低和工艺能耗高等问题,结合模糊PID算法,提出将溶解氧浓度控制转化为对鼓风机电机转速的控制,并采用模糊规则对鼓风机电机转速进行精确控制的方法.仿真结果表明,构建的模糊PID控制器达到系统设定的溶解氧浓度值仅需75 s,与传统的PID算法相比,缩短了45 s;在实际应用中,通过模糊PID控制...     

加热炉分数阶PID温度自适应控制系统设计

针对加热炉温度控制系统控制器参数不易选择的问题，提出一种分数阶自适应PID串级控制方法实现控制器参数自动调整。首先以分数阶PID控制器分别作为温度主控制器和燃气流量控制器，实现加热炉串级温度控制；其次应用自适应理论对控制器进行改进，设计了自适应分数阶PID控制器。最后通过数值仿真，验证了所设计控制系统对加热炉温度控制的有效性和可行性。     

在线自适应模糊PID控制器的设计与仿真

介绍模糊理论与PID控制相结合的智能模糊PID控制技术,分析模糊PID控制器的量化因子和比例因子对控制器性能的影响,由此指出常规模糊PID控制器在工业应用的局限性,并提出一种基于相关量化的在线自适应算法。仿真结果表明:在参考输入改变和受控对象参数漂移时,相比常规模糊PID控制器,改进的控制器具有更好的动态和稳态性能。     

PVC胶槽温度模糊PID控制系统

为提高PVC胶槽温度控制的可靠性和精度,将模糊算法与PID算法结合并应用于PVC胶槽温度控制系统中,通过两种控制算法的优势互补,利用模糊控制算法求得PID参数修正系数,实现PID控制器3个参数的在线自调整。仿真结果表明:PVC胶槽温度模糊PID控制器的控制性能明显地优于常规PID控制器,温度控制精度达到±1℃,满足了PVC胶槽温度参数动态变化实时调节控制的需要,具有较好的自适应调节和鲁棒性。     

注射机料筒温度灰色预测控制研究

将灰色预测算法和模糊控制算法相结合,两种算法互为补充,建立灰色模糊控制器对注射机温度控制系统进行优化。以二板直压式注射机控制器为模型搭建了MATLAB仿真平台对算法进行验证。仿真结果表明:提出的算法能够很好地优化PID控制参数,大大减小了系统的超调量和调节时间,其算法性能优良,极大地提升了注射机温度控制系统的性能。     

Insect antifeedant properties of anthranoids from the genusVismia

Vismiones and ferruginins, representatives of a new class of lypophilic anthranoids from the genusVismia were found to inhibit feeding in larvae of species ofSpodoptera, Heliothis, and inLocusta migratoria.     

Direct observation of freeze-thaw instability of latex coatings via high pressure freezing and cryogenic SEM

Despite its industrial importance, the subject of freeze-thaw (F/T) stability of latex coatings has not been studied extensively. There is also a lack of fundamental understanding about the process and the mechanisms through which a coating becomes destabilized. High pressure (2100 bar) freezing fixes the state of water-suspended particles of polymer binder and inorganic pigments without the growth of ice crystals during freezing that produce artifacts in direct imaging scanning electron microscopy (SEM) of fracture surfaces of frozen coatings. We show that by incorporating copolymerizable functional monomers, it is possible to achieve F/T stability in polymer latexes and in low-VOC paints, as judged by the microstructures revealed by the cryogenic SEM technique. Particle coalescence as well as pigment segregation in F/T unstable systems are visualized. In order to achieve F/T stability in paints, latex particles must not flocculate and should provide protection to inorganic pigment and extender particles. Because of the unique capabilities of the cryogenic SEM, we are able to separate the effects of freezing and thawing, and study the influence of the rate of freezing and thawing on F/T stability. Destabilization can be caused by either freezing or thawing. A slow freezing process is more detrimental to F/T stability than a fast freezing process; the latter actually preserves suspension stability during freezing. Presented at the 82nd Annual Meeting of the Federation of Societies for Coatings Technology, October 27–29, 2004 in Chicago, IL. Tied for first place in The John A. Gordon Best Paper Competition.     

Ethanol and (−)-α-Pinene: Attractant Kairomones for Bark and Ambrosia Beetles in the Southeastern US

In 2002–2004, we examined the flight responses of 49 species of native and exotic bark and ambrosia beetles (Coleoptera: Scolytidae and Platypodidae) to traps baited with ethanol and/or (−)-α-pinene in the southeastern US. Eight field trials were conducted in mature pine stands in Alabama, Florida, Georgia, North Carolina, and South Carolina. Funnel traps baited with ethanol lures (release rate, about 0.6 g/day at 25–28°C) were attractive to ten species of ambrosia beetles (Ambrosiodmus tachygraphus, Anisandrus sayi, Dryoxylon onoharaensum, Monarthrum mali, Xyleborinus saxesenii, Xyleborus affinis, Xyleborus ferrugineus, Xylosandrus compactus, Xylosandrus crassiusculus, and Xylosandrus germanus) and two species of bark beetles (Cryptocarenus heveae and Hypothenemus sp.). Traps baited with (−)-α-pinene lures (release rate, 2–6 g/day at 25–28°C) were attractive to five bark beetle species (Dendroctonus terebrans, Hylastes porculus, Hylastes salebrosus, Hylastes tenuis, and Ips grandicollis) and one platypodid ambrosia beetle species (Myoplatypus flavicornis). Ethanol enhanced responses of some species (Xyleborus pubescens, H. porculus, H. salebrosus, H. tenuis, and Pityophthorus cariniceps) to traps baited with (−)-α-pinene in some locations. (−)-α-Pinene interrupted the response of some ambrosia beetle species to traps baited with ethanol, but only the response of D. onoharaensum was interrupted consistently at most locations. Of 23 species of ambrosia beetles captured in our field trials, nine were exotic and accounted for 70–97% of total catches of ambrosia beetles. Our results provide support for the continued use of separate traps baited with ethanol alone and ethanol with (−)-α-pinene to detect and monitor common bark and ambrosia beetles from the southeastern region of the US.     

Methyl 2,4,6-decatrienoates Attract Stink Bugs and Tachinid Parasitoids

Halyomorpha halys (Stål) (Pentatomidae), called the brown marmorated stink bug (BMSB), is a newly invasive species in the eastern USA that is rapidly spreading from the original point of establishment in Allentown, PA. In its native range, the BMSB is reportedly attracted to methyl (E,E,Z)-2,4,6-decatrienoate, the male-produced pheromone of another pentatomid common in eastern Asia, Plautia stali Scott. In North America, Thyanta spp. are the only pentatomids known to produce methyl 2,4,6-decatrienoate [the (E,Z,Z)-isomer] as part of their pheromones. Methyl 2,4,6-decatrienoates were field-tested in Maryland to monitor the spread of the BMSB and to explore the possibility that Thyanta spp. are an alternate host for parasitic tachinid flies that use stink bug pheromones as host-finding kairomones. Here we report the first captures of adult and nymph BMSBs in traps baited with methyl (E,E,Z)-2,4,6-decatrienoate in central Maryland and present data verifying that the tachinid, Euclytia flava (Townsend), exploits methyl (E,Z,Z)-2,4,6-decatrienoate as a kairomone. We also report the unexpected finding that various isomers of methyl 2,4,6-decatrienoate attract Acrosternum hilare (Say), although this bug apparently does not produce methyl decatrienoates. Other stink bugs and tachinids native to North America were also attracted to methyl 2,4,6-decatrienoates. These data indicate there are Heteroptera in North America in addition to Thyanta spp. that probably use methyl 2,4,6-decatrienoates as pheromones. The evidence that some pentatomids exploit the pheromones of other true bugs as kairomones to find food or to congregate as a passive defense against tachinid parasitism is discussed.     

2007～2008年世界塑料工业进展

收集了2007年7月～2008年6月世界塑料工业的相关资料,介绍了2007～2008年国外塑料工业的发展情况,提供了世界塑料产量、消费量及全球各类树脂的需求量及产能情况.按通用热塑性树脂(聚乙烯、聚丙烯、聚苯乙烯、聚氯乙烯、ABS树脂)、工程塑料(尼龙、聚碳酸酯、聚甲醛、热塑性聚酯、聚苯醚)、特种工程塑料(聚苯·硫醚、液晶聚合物、聚醚醚酮)、通用热固性树脂(酚醛、聚氨酯、不饱和聚酯树脂、环氧树脂)不同品种的顺序,对树脂的产量、消费量、供需状况及合成工艺、产品应用开发、树脂品种的延伸及应用的进一步扩展等技术作了详细介绍.     

2005～2006年国外塑料工业进展

收集了2005年7月～2006年6月国外塑料工业的相关资料,介绍了2005—2006年国外塑料工业的发展情况。提供了世界塑料产量、消费量及全球各类树脂生产量以及各国塑料制品的进出口情况。作为对比,介绍了中国塑料的生产情况。按通用热塑性树脂（聚乙烯、聚丙烯、聚苯乙烯、聚氯乙烯、ABS树脂）、工程塑料（聚酰胺、聚碳酸酯、聚甲醛、热塑性聚酯、聚苯醚）、通用热固性树脂（酚醛、聚氨酯、不饱和树脂、环氧树脂）、特种工程塑料（聚苯硫醚、液晶聚合物、聚醚醚酮）的品种顺序,对树脂的产量、消费量、供需状况及合成工艺、产品开发、树脂品种的延伸及应用的扩展作了详细的介绍。