新型双刚圈航空轮胎的仿真研究

以46/17R20航空子午线轮胎和一种新型高性能新概念轮胎——双刚圈航空轮胎为研究对象,利用ABAQUS软件分析静载荷工况下的径向和纵向刚度以及以288 km·h-1初始水平速度的制动过程中胎面受力及接地性能。结果表明:与传统航空轮胎相比,静载荷工况下双刚圈航空轮胎的径向刚度显著提高,纵向刚度略有下降;制动工况下双刚圈航空轮胎胎面等效应力以及径向和纵向接触压力分布规律均明显较优。双刚圈航空轮胎的承载能力、接地性能和制动性能均优于传统航空轮胎,其中外刚圈轴向长度适中的双刚圈航空轮胎的综合性能最优。     

245/70R16轮胎的有限元分析

以Abaqus为平台,采用有限元法对245/70R16轮胎进行分析,研究负荷、外倾角和侧偏角对轮胎整体静力学与动力学性能、温度场与滚动阻力场分布的影响。结果表明:随着负荷的增大,轮胎整体的变形和接地面积增大,接地性能变差,肩部与胎圈部位的应变能密度增大,轮胎的横向刚度略有减小,纵向刚度和径向刚度略有增大,而旋转刚度明显增大,肩部和胎圈最高点的温度升高;随着外倾角的增大,轮胎的滚动温度场与滚动阻力场分布趋向于不对称,滚动阻力和滚动阻力系数均增大。     

制动过程中轿车子午线轮胎的接触力学性能研究

采用室内平板式轮胎试验机模拟轮胎的制动过程,研究轮胎胎面纵向位移线性段长度、纵向刚度、纵向最大摩擦力和垂直合力偏心距,并用串联Voight模型解释轮胎试验过程中的现象.胎面纵向位移线性段长度、纵向刚度、纵向最大摩擦力和垂直合力偏心距均随负荷增大而增大,且负荷的影响大于充气压力.     

基于ABAQUS建模的轮胎接地特性及静态刚度的分析研究

利用ABAQUS软件对三维轮胎接地模型进行建模,模拟了不同充气压力、不同垂直载荷下的轮胎接地情况,并对轮胎的静态刚度进行了分析。结果表明,固定垂直载荷下,随着气压的增大,法向应力最大值由胎冠两侧向胎冠靠拢。标准大气压下,随着载荷的增大,轮胎最大法向应力由胎冠中心向轮胎两侧移动。径向刚度、横向刚度、单位长轴纵向刚度、扭转刚度都与充气压力有关,只有扭转刚度受垂直载荷影响。     

基于纵向力的轮胎模型及参数分析

通过垂直负荷分布修正和滑动摩擦因数参数化,建立轮胎纵向力模型,利用其对轮胎纵向力特性进行分析,并研究各因素对轮胎纵向力的影响。结果表明,随着静摩擦因数的增大,接地胎面完全滑移的滑移率增大,滑移力（Fsx）和附着力（Fax）增大;纵向刚度主要影响峰值前的纵向合力,随着轮胎纵向刚度和接地印痕长度的增大,接地胎面完全滑移的滑移率减小,Fax减小,Fsx增大。     

225/65R17102H公路型轮胎的设计

介绍225/65R17 102H公路型轮胎的设计。胎面花纹设计：采用胎面花纹块精确比例、胎面花纹沟边、胎面花纹深浅钢片、5种单元节距以及宽大的块状肩部花纹设计;结构设计：采用宽大的接地面、加深沟槽和加强的胎体材料设计。通过轮胎有限元仿真分析,轮胎的接地压力分布均匀,接地形状方正。成品轮胎的胎圈强度、高速性能和耐久性能均满足国家标准要求,实车评价其在噪声、乘坐舒适性以及干湿地操控性能方面表现优异。     

下胎侧具有支撑设计的斜交工程机械轮胎的研发

工程机械轮胎．尤其是用于大型推土机和装载机上的工程机械轮胎，由于使用环境恶劣，负荷大，下沉量大．且使用过程中启动和制动频繁、转弯较多，因此．对胎圈的性能和下胎侧支撑性能要求较高。但传统设计的工程机械轮胎由于胎圈和下胎侧设计不尽合理，从而引起下胎侧的支撑性能以及耐刺扎性均不够理想。     

受力轮胎花纹块与胎体变形量测试系统的研究

开发了一种测量在径向力、切向力和侧向力作用下轮胎胎面花纹块变形量和胎体变形量等参数的试验系统。该系统可以在不同条件下进行如下参数的测量 :轮胎胎面花纹块变形量、胎体变形量、轮胎的接地印迹、轮胎下沉量及滚动半径、轮胎与路面的摩擦因数、轮胎径向刚度、侧向刚度和切向及扭转刚度等。该系统为汽车的动态仿真提供更接近实际的轮胎模型及参数数据 ;可以验证轮胎有限元计算结果的精度和误差 ;为轮胎的振动与噪声仿真计算与分析提供了理论依据。重要的是可以通过该系统研究轮胎结构参数与轮胎各种性能的关系 ,以缩短新产品的开发周期。     

辐板式非充气塑料轮胎静负荷工况下的力学性能分析

提出一种聚氨酯辐板与橡胶胎面相复合的辐板式非充气塑料轮胎,并利用有限元软件ABAQUS在静负荷工况下对相同规格的辐板式塑料轮胎和子午线橡胶轮胎的接地性能和力学性能进行分析和对比。结果表明,相比子午线橡胶轮胎,辐板式塑料轮胎接地印痕形状更合理,沿胎面横向的接地压力分布更均匀,减轻了易发生磨损胎肩的负担;另外,辐板式塑料轮胎径向刚度明显较高,并且在接地区域内的弯曲变形的支撑板起到了缓冲和承载的作用,说明辐板式塑料轮胎具有优越的承载性能和良好的舒适性能。     

胎面基部胶厚度对轮胎性能的影响

通过控制胎面挤出过程,调整基部胶厚度占胎面总厚度的比例(以下简称基部胶厚度占比,分别取20%,35%和50%),研究胎面基部胶厚度占比对轮胎性能的影响。结果表明,适当增大基部胶厚度占比可以提高轮胎的耐久性能,减小轮胎过坎冲击力,提高乘坐舒适性,增大侧向力,提高操纵性能,增大纵向力和接地面积,提高抓着性能和制动性能,并且降低滚动阻力系数,提高燃油经济性。     

Sapindaceae,cyanolipids, and bugs

Scentless plant bugs (Heteroptera: Rhopalidae) are so named because adults of the Serinethinae have vestigial metathoracic scent glands. Serinethines are seed predators of Sapindales, especially Sapindaceae that produce toxic cyanolipids. In two serinethine species whose ranges extend into the southern United States,Jadera haematoloma andJ. sanguinolenta, sequestration of host cyanolipids as glucosides renders these gregarious, aposematic insects unpalatable to a variety of predators. The blood glucoside profile and cyanogenesis ofJadera varies depending on the cyanolipid chemistry of hosts, and adults and larvae fed golden rain tree seeds (Koelreuteria paniculata) excrete the volatile lactone, 4-methyl-2(5H)-furanone, to which they are attracted.Jadera fed balloon vine seeds (Cardiospermum spp.) do not excrete the attractive lactone. Loss of the usual heteropteran defensive glands in serinethines may have coevolved with host specificity on toxic plants, and the orientation ofJadera to a volatile excretory product could be an adaptive response to save time.Mention of a commercial product does not consititute an endorsement by the USDA.     

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.     

Many Drugs of Abuse May Be Acutely Transformed to Dopamine,Norepinephrine and Epinephrine In Vivo

It is well established that a wide range of drugs of abuse acutely boost the signaling of the sympathetic nervous system and the hypothalamic–pituitary–adrenal (HPA) axis, where norepinephrine and epinephrine are major output molecules. This stimulatory effect is accompanied by such symptoms as elevated heart rate and blood pressure, more rapid breathing, increased body temperature and sweating, and pupillary dilation, as well as the intoxicating or euphoric subjective properties of the drug. While many drugs of abuse are thought to achieve their intoxicating effects by modulating the monoaminergic neurotransmitter systems (i.e., serotonin, norepinephrine, dopamine) by binding to these receptors or otherwise affecting their synaptic signaling, this paper puts forth the hypothesis that many of these drugs are actually acutely converted to catecholamines (dopamine, norepinephrine, epinephrine) in vivo, in addition to transformation to their known metabolites. In this manner, a range of stimulants, opioids, and psychedelics (as well as alcohol) may partially achieve their intoxicating properties, as well as side effects, due to this putative transformation to catecholamines. If this hypothesis is correct, it would alter our understanding of the basic biosynthetic pathways for generating these important signaling molecules, while also modifying our view of the neural substrates underlying substance abuse and dependence, including psychological stress-induced relapse. Importantly, there is a direct way to test the overarching hypothesis: administer (either centrally or peripherally) stable isotope versions of these drugs to model organisms such as rodents (or even to humans) and then use liquid chromatography-mass spectrometry to determine if the labeled drug is converted to labeled catecholamines in brain, blood plasma, or urine samples.     

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.     

2008～2009年世界塑料工业进展

收集了2008年7月～2009年6月世界塑料工业的相关资料,介绍了2008～2009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、环氧树脂、不饱和聚酯树脂)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。