共查询到20条相似文献,搜索用时 62 毫秒
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研究不同摩擦因数胎面胶对轿车子午线轮胎的滚动阻力、静态刚性、接地印痕、六分力特性及整车性能的影响。结果表明:使用3种胎面胶的轮胎的滚动阻力接近;随着胎面胶摩擦因数的减小,轮胎的纵向刚性和扭转刚性变化较大,径向刚性和横向刚性变化不大,轮胎的包络刚性随胎面胶硬度的增大而增大;采用较大摩擦因数胎面胶的方案A轮胎的接地面积及矩形比较大,3种方案轮胎其他接地特性参数差异较小;采用较小摩擦因数胎面胶的方案C轮胎的侧偏刚度、回正刚度和纵滑刚度最大,成品轮胎的摩擦因数与胎面胶的摩擦因数呈正相关,但数值差异略大,轮胎的侧向力峰值、回正力矩峰值、纵向力峰值随胎面胶摩擦因数的增大而增大;轮胎干地刹车距离与胎面胶摩擦因数呈负相关,操控稳定性受轮胎侧偏刚度和回正刚度的影响较大,舒适性受胎面胶硬度的影响较大。 相似文献
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三角平衡轮廓轮胎是一种新型的轮胎结构,以低扁平率的传统轮廓轮胎255/30R22为基础,在其胎肩处和胎侧处增加高强度的支撑块来提高轮胎的性能。支撑块起到支撑胎面的作用,提高了胎侧的刚度。本文以滚动阻力计算公式和材料内耗机理为基础,用ABAQUS软件分别模拟2种轮胎的滚动阻力来验证三角平衡轮廓轮胎是否具有较低的滚动阻力。首先建立三角平衡轮廓轮胎和255/30R22轮胎的三维模型,施加相同载荷,对其进行以60km/h滚动工况的力学分析,算出单元积分点的生热率,提取每个单元的体积,最后计算每一种胶料的滚动阻力及轮胎总滚动阻力。通过两者的对比,三角平衡轮廓轮胎的滚动阻力仅18.7N,低于255/30R22轮胎滚动阻力的二分之一。 相似文献
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以超声速气流冲击轴线与来流方向相一致的带有金属泡沫多孔前置体的实体圆柱为研究对象,采用连续尺度单区域法数值模拟泡沫多孔前置体内部的流场及气动热效应。多孔域阻力特性基于分布阻力法加入,选用局部非热平衡模型,考虑流体相与固体相的传热温差,并通过Rosseland扩散模型加入固体相的辐射热效应。研究发现,在模拟气流工况下前置有一定长度的柱状泡沫多孔材料可显著降低模型激波阻力和前缘气动热效应,此外相对于气动压缩效应对温度场的影响黏性耗散效应较小。 相似文献
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Dinesh Singh J. K. Gehlawat Musti S. Rao 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》1990,47(2):127-136
Oslefins and diolefins are important intermediates in the petrochemical industry and the future promises a further substantial increase in demand. While several catalysts have been formulated in the past for the abstraction of hydrogen from butenes and propylene, these catalysts are inefficient in the abstraction of first hydrogen from butane. Bismuth molybdates (β and γ-phases) containing iron oxide and supported on alumina are used as catalysts in the present investigation on the oxidative dehydrogenation of n-butane. Effects of catalyst content, temperature and oxygen: n-butane ratio on conversion and selectivity to butadiene and (C4H8 + C4H6) are studied in the following ranges of experimental conditions: β-bismuth molybdate/100 mol support I(K), 3–9; γ-bismuth molybdate/100 mol support I(K), 5-20; temperature, 400–500°C; O2: butane ratio, 0.6:1.7. 相似文献
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A viscometer used to measure the viscosity of 10 μl of a liquid, must be miniaturized down, and the liquid velocity gradient in the channel used to determine the viscosity coefficient. Two major factors that affect the liquid velocity are the mechanical forces exerted by the mechanical motors and electromagnetic forces. In this study, electrowetting on dielectric (EWOD) is adopted to drive liquids. Variously sized electrodes on a chip, and two shapes of channel are employed to measure the velocity gradient to determine the viscosity coefficient. The device is fabricated by microelectromechanical system (MEMS) technology. The dielectric layer used in EWOD has a high dielectric constant, BST (Ba0.7Sr0.3TiO3), to reduce the required applied voltage; its surface is coated with hydrophobic polymer, polytetrafluoro-ethylene (PTFE, Teflon® AF DuPont). Experimental results demonstrate that liquids can be pulled at 660 μm/s in linear channels by applying a voltage of 15 V. 相似文献
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考登钢作为一种高耐候结构钢,广泛应用于各个领域。在火力发电方面,考登钢主要应用在工作环境比较恶劣的烟气加热器和空气预热器中。考登钢表面涂搪的目的就是进一步提高其耐腐蚀性能,延长使用寿命。为了提高考登钢元件的使用寿命,对考登钢表面涂搪瓷的可行性、密着性能、瓷釉、工艺控制、质量保证等方面进行了研究。 相似文献
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In reexamining medium effects on photochemical reactions, we have emphasized those on unequilibrated excited species such as the Franck-Condon species. Despite recent advances in femtochemistry, such a discussion in molecular photochemistry is uncommon, and the problem remains challenging on account of the extremely short-lived excited species. However, in such cases, a small perturbation resulting from, for example, weak guest-host interactions could turn into a determining factor in dictating the course of a photochemical channel of deactivation. Examples of medium-directed diabatic processes have been examined with this idea in mind. A modified view on rhodopsin photoisomerization is presented along with the consideration that confinement does not necessarily lead to inhibition of reactions of the trapped substrate. 相似文献
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研究了温度和pH值对漆酶酶活以及漆酶处理纤维压制纤维板性能的影响。结果表明,pH较低、温度较高时漆酶酶活较高,压制的纤维板强度性能较好。但温度太高(60~80℃),延长加热时间,漆酶稳定性变差,酶活明显降低,压制纤维板的强度下降。 相似文献
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采用密度泛函理论(DFT)考察了丙烷在Pt(111)表面上脱氢生成丙烯的反应机理。通过在Pt(111)面上预吸附一定数量H原子模拟共吸附H对丙烷脱氢过程的影响。结果表明:H共吸附能降低丙烷及其脱氢产物的吸附能,促进丙烯脱附,有利于提高丙烯的选择性;H共吸附会导致丙烷脱氢能垒变大,降低催化剂的脱氢活性;共吸附的影响随着H覆盖率增加而增大。 相似文献