同向双螺杆几何设计计算软件原理及功能分析

介绍了自洁型同向双螺杆的基本几何关系，分析了同向双螺杆几何设计计算软件的功能，该软件以设计同向双曼杆螺纹元件及捏合盘外廓曲面为基础，采用法向修正方法计算间隙，提出了端面接合误差的概念并实现了对该误差的修正算法，可根据不同需要计算轴截面，横截面及斜截面中螺纹曲线的数据，该软件所具备的功能是双螺杆CAD／CAM的基础。     

自洁型同向双螺杆几何设计及间隙修正原理探讨

从工程应用的角度论述自洁型同向双螺杆的几何设计原理,从两根螺杆最基本的相对运动关系和几何关系出发,推导出可用于工程设计的同向双螺杆元件外廓几何形状的数学表达式。讨论设计中所涉及的间隙修正问题,并给出解决这一问题的数学方法。这些工作为后续的设计计算软件开发打下了良好的基础。     

平行双螺杆挤出机的螺杆几何学

在Booy全啮合理论的基础上,从螺杆元件加工性能的角度,对平行双螺杆挤出机螺杆几何学进行了深入研究.利用有限元数值模拟的方法从产量、齿轮箱轴承受力、比能耗、停留时间以及螺杆元件力学性能等方面量化对比了法向等间隙修正法和中心距修正法设计螺杆元件的性能.结果表明:法向等间隙修正法设计螺杆元件的加工性能更加优异.研究内容对平行双螺杆挤出机螺杆元件设计具有一定的指导意义.     

啮合异向旋转双螺杆三维实体造型研究

从啮合异向旋转双螺杆相对运动原理及其截面形状的几何造型方程入手 ,借助CAD的VBA三维造型及计算分析功能 ,分析研究了螺杆理论端面曲线所生成的三维实体模型与实际螺杆的差异 ,找出其中的关系 ,方便有效地使螺杆的三维实体造型与实际螺杆相符 ,从而使螺杆三维实体造型更具实际应用价值     

新型同向双螺杆元件几何造型初探

随着双螺杆挤出机的高速、高效化,常规的螺杆元件越来越无法满足需要,因此设计新型的双螺杆元件变得尤为重要。提高物料在螺杆中的剪切、拉伸是物料充分混合的条件,拉伸速率的效果尤为明显,而这又恰恰是常规螺纹元件所不具备的。螺杆产生的拉伸速率与其几何形状有关,因而要在造型时尽量使双螺杆具有较强的拉伸作用。     

啮合导向旋转双螺杆三维实体造型研究

从啮合异向旋转双螺杆相对运动原理及其截面形状的几何造型方程入手，借助CAD的VBA三维造型及计算分析功能，分析研究了螺杆理论端面曲线所生成的三维实体模型与实际螺杆的差异，找出其中的关系，方便有效地使螺杆的三维实体造型与实际螺杆相符，从而使螺杆三维实体造型更具实际应用价值。     

啮合同向旋转双螺杆挤出机中波状螺杆元件的熔体输送和混合机理研究

作者把波状单螺杆的概念应用到同向旋转双螺杆挤出机中,设计出一种新型螺杆元件,并建立了描述这种新型螺杆元件熔体输送和混合机理的理论模型。利用流体有限元方法对流场进行了数值分析,对某些计算结果进行了实验验证,理论计算和实验结果吻合,说明作者建立的理论模型是正确的。实验结果表明,波状双螺杆元件的混合性能优于普通双螺杆元件。     

双螺杆挤出实验中影响螺杆填充率的相关因素

利用双螺杆挤出实验中的实验数据曲线,对影响螺杆填充率的诸相关因素进行分析。在螺杆几何结构及螺杆元件组合形式确定之后,不同的操作工况条件下对应有不同的螺杆最大允许填充率,在正常操作中,螺杆的填充率不能大于最大允许值。     

啮合同向双螺杆挤出机新型螺杆元件的结构和性能

概述了啮合同向双螺杆挤出机新型螺杆元件的结构和性能,并对螺杆元件今后的设计提出了看法。     

新型偏心双螺杆挤出机流域混合特性

基于非对称流场的混沌混合理论,设计了一种新型的偏心双螺杆挤出机。通过对比传统普通螺杆元件与新型偏心螺杆元件,偏心距不仅决定了螺杆的端面形状,也改变了螺槽形状,使同一导程内的2个独立的C型室螺槽形成一个ω型室螺槽。利用Polyflow软件分别对传统双螺杆挤出机与3种不同偏心距螺杆元件的新型双螺杆挤出机进行模拟仿真,分析了压力场、速度场与混合指数分布规律,计算了4种双螺杆挤出机流场的停留时间分布、分离尺度、最大剪切应力等混合表征系数。结果表明,与传统双螺杆挤出机相比,偏心双螺杆挤出机压力分布不均匀,正负压压力值增大,因此,压力差增大,使熔体回流速度增大,混合效果更佳;拉伸流区域增大,混合能力增强;熔体在流体域内的总体停留时间缩短,混合效果更佳;分离尺度数值下降较快,混合效率较高;偏心螺杆元件对流体的剪切应力增大,分散混合能力增强。     

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。