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针对交通状态转变时刻的判断问题进行了研究,在传统的交通状态研究模型基础上提出了时空图在状态判别中的应用,并在利用前人提出的调整累积曲线方法进行了比较,证实了引入该方法的有效性和准确性,提高了对交通拥挤转变时刻的判定上的准确率,在交通流特性的研究中起到十分重要的作用。 相似文献
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今年8月,记者在安徽对五羊-本田的市场情况作了一定了解,并在杨韶民总经理的安排下,走访了皖北的宿州地区。之前,杨韶民以多年的行业经验,结合国家政策,谈到了他对目前安徽摩托市场的理解和预测,同时综合分析了五羊-本田工厂方面在新品上的推陈,以及在市场上的竞争能力。 相似文献
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根据在美国缅因州一年的驾驶经历及驾考经验,对缅因州的驾考及交通规则进行了分析。针对中美两国在驾考规则及考试内容上一些较大的区别进行了分析,并对在交通规则上的存在的差异进行了讨论,最后对中美两国在驾考方面及交通规则上的优劣进行了对比分析,并针对中国的现状提出了建设性的建议。 相似文献
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文章系统介绍了用于制造发动机罩的各种新型轻质材料,并根据发动机罩的结构特点,比较了各种新型轻质材料在发动机罩上的应用.通过比较,分析了各种材料在发动机罩上应用的优缺点,并得出了新型材料在发动机罩上的应用趋势. 相似文献
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介绍了工程塑料、陶瓷基复合材料以及金属基复合材料在汽车发动机及周边主要零部件的应用情况及其局限性,阐述了这些材料目前面临的问题及其发展前景。指出虽然一些复合材料具有高温强度好、耐磨性及耐腐蚀性好等优点,在发动机部分零件的制造上有着一定的优势;但由于大多数复合材料易燃,且会对环境产生一些不利的影响,所以其无害化回收处理问题尚待解决。 相似文献
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《JSAE Review》2002,23(3):365-370
Improvement in fuel consumption rate requires a reduction in vehicle weight. Research and development for materials substitution in the brake rotor, from the conventional cast iron to aluminum, has been undertaken. In this study, we developed aluminum metal matrix composites brake rotor and pads, which have equivalent braking effects and wear resistance to those of the conventional cast iron rotor, by optimization of the quantities and the particle diameter ratio of hard particles used for the rotor and the pad. 相似文献
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综述了金属复合材料、陶瓷复合材料及连续纤维的SMC在汽车上的应用状况,并与传统的汽车材料在性能、特点等方面进行了比较,论述了复合材料在汽车上得到广泛应用的原因。对车用复合材料的发展趋势进行分析。 相似文献
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沥青混合料粘弹性能微观力学分析 总被引:2,自引:1,他引:1
利用Moil—Tanaka等效夹杂微观力学理论研究了沥青混合料的粘弹性能。将沥青混合料看作刚性粗集料颗粒夹杂于粘弹性沥青砂浆基体内的复合材料,对集料夹杂和沥青砂浆基体的本构方程分别进行Laplace变换成弹性问题,在Laplace空间域内应用Mori—Tanaka等效夹杂和宏观平均理论由沥青砂浆粘弹性能推导出了沥青混合料的粘弹性能。结果表明,粗集料颗粒夹杂对粘弹性沥青基体性能具有增强作用,沥青混合料粘弹本构方程可表示为粗集料增强系数与沥青基体粘弹本构方程的乘积形式。利用增强系数可以从性质较均匀的沥青基体粘弹性来预测性能较复杂的沥青混合料的粘弹性。其中增强系数大于1且随粗集料体积分数或沥青基体的泊松比增加而增大,粗集料体积分数对增强系数的增大作用远大于沥青砂浆基体泊松比对其的影响。 相似文献
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D. Kim Y. H. Kim S. Gururaja M. Ramulu 《International Journal of Automotive Technology》2010,11(6):849-855
The random direction short Glass Fiber Reinforced Plastics (GFRP) have been prepared by two compression moulding processes,
namely the Preform and Sheet Moulding Compound (SMC) processes. Cutting force analysis and surface characterization are conducted
on the random direction short GFRPs with varying fiber contents (25∼40%). Edge trimming experiments are preformed using carbide
inserts with varing the depth of cut and cutting speed. Machining characteristics of the Preform and SMC processed random
direction short GFRPs are evaluated in terms of cutting forces, surface quality, and tool wear. It is found that composite
primary processing and fiber contents are major contributing factors influencing the cutting force magnitudes and surface
textures. The SMC composites show better surface finish over the Preform composites due to less delamination and fiber pullouts.
Moreover, matrix damage and fiber protrusions at the machined edge are reduced by increasing fiber content in the random direction
short GFRP composites. 相似文献
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为了从细观结构上研究碾压混凝土的劈裂抗拉强度及其尺寸效应,采用随机骨料模型,在细观层次上将碾压混凝土看成是由硬化水泥粉煤灰砂浆体、粗骨料颗粒、二者间的黏结带和砂浆层面构成的三相非均质复合材料;利用有限元方法数值模拟研究碾压混凝土的细观损伤断裂和劈裂抗拉,对其劈裂抗拉强度及其尺寸效应进行了研究。结果表明:黏结带和层面是碾压混凝土劈裂抗拉破坏的薄弱环节;碾压混凝土试件的劈裂抗拉强度存在明显的尺寸效应,和一般的试验规律基本吻合;随机生成骨料结构的方法,可以有效地研究碾压混凝土的细观损伤断裂。 相似文献
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Mori-Tanaka equivalent inclusion micromechanics theory was employed to investigate the viscoelasticity of asphalt mixture Asphalt mixture was regarded as composites which treated coarse aggregate as a rigid inclusion and the mixture of fine aggregate,filler and binder as viscoelastic matrix The constitutive relations of coarse aggregate inclusion and fine aggregate-filler-binder matrix were converted into elastic problems by Laplace transformation Then the Mori-Tanaka equivalent inclusion and average theory were used to deduce the
viscoelastic performance of asphalt mixture based on that of asphalt mortar in
Laplace space The result shows that (1) coarse aggregate inclusion can enhance
the viscoelastic performance of fine aggregate?filler?binder matrix and viscoelastic constitutive relation of asphalt mixtures can be expressed as the product of an enhancement coefficient of coarse aggregate and the viscoelastic constitutive relation of fine aggregate?filler?binder matrix; (2) the viscoelasticity of the complex asphalt mixture can be predicted from the viscoelasticity of the homogeneous fine aggregate?filler?binder matrix by using the nhancement coefficient; (3) the enhancement coefficient is higher than 10 and it rises with increasing of coarse aggregates' volumetric fraction or Poisson's ratio of fine aggregate-filler-binder matrix but the effect of the former is more important than that of the latter 相似文献