热处理工艺对铸造汽车覆盖件模具钢的耐磨性研究

对不同淬火、回火温度与不同磨损条件下的铸造汽车覆盖件模具钢进行了磨损试验,研究磨损率与回火温度、摩擦参数等因素的关系,观察摩擦表面的显微组织和摩擦学性能.结果表明:试验用模具钢材料的耐磨性能与材料的硬度有一定关系,与淬火、回火温度有很大关系,更与磨损过程中加载载荷、滑动速率和摩擦距离等因素有关.回火温度对模具钢材料的硬度和耐磨性起到了一定的作用,500℃左右时硬度最大.600℃回火后,组织中主要成分变为马氏体与托氏体.在滑动速率较高、回火温度较低时,随着回火温度升高,磨损率降低速度明显;在加载载荷较大、回火温度较低时,随着回火温度的升高,磨损率降低速度明显.不同的滑动速率以及加载载荷情况下的磨损机理主要为黏着磨损和磨粒磨损等两种.     

基于模糊证据推理的汽车制造产业网络环境复杂性测度

环境复杂性是汽车制造产业网络复杂性的主要诱因。利用指标波动程度测度复杂性的思想,建立表征汽车制造产业网络外部环境的指标体系,构建指标变动程度的模糊信度结构模型,运用模糊证据推理算法结合熵值理论对多指标进行信息融合,并利用灰色关联分析方法评估复杂性测度结果。通过2002~2012年汽车行业数据的实证研究,结果表明:经济环境与国际环境的波动是导致汽车制造产业网络复杂性的最主要因素,技术环境和市场环境次之;近10年来我国汽车制造产业网络外部环境经历了两次较大波动,总体复杂性呈现增长趋势。本研究可为汽车产业环境复杂性测度及应对提供思路参考。     

Parallel computation of incompressible flows with complex geometries

We present our numerical methods for the solution of large-scale incompressible flow applications with complex geometries. These methods include a stabilized finite element formulation of the Navier–Stokes equations, implementation of this formulation on parallel architectures such as the Thinking Machines CM-5 and the CRAY T3D, and automatic 3D mesh generation techniques based on Delaunay–Voronoi methods for the discretization of complex domains. All three of these methods are required for the numerical simulation of most engineering applications involving fluid flow. We apply these methods to the simulation of airflow past an automobile and fluid–particle interactions. The simulation of airflow past an automobile is of very large scale with a high level of detail and yielded many interesting airflow patterns which help in understanding the aerodynamic characteristics of such vehicles. © 1997 John Wiley & Sons, Ltd.     

过渡金属型汽车尾气净化催化材料的制备及性能研究

采用固定床反应装置,模拟汽车尾气的组成成分,以CO/NH3为探针反应,分别研究了活性成分负载量及焙烧温度等因素对过渡金属氧化物催化材料MnOx/γ-Al2O3和Mn-Ce-O(x)/γ-Al2O3的催化活性的影响,并考察了该催化剂的抗硫化中毒性能和抗老化性能。在该研究条件下,氧化物负载量在0.12(质量分数),焙烧温度在700℃左右时,催化剂对NO-CO体系中CO的氧化率在85%以上。将催化剂在3.0%的SO2/空气气氛中强制中毒后,其对CO/NO体系中CO的催化转化率明显下降,但抗老化实验表明,该催化剂经900℃下,12%水蒸汽老化 60 h后,对CO的催化活性不仅没有下降,反而略有升高,说明该催化剂具有良好的抗老化性能和高温活性。     

Catalytic Reduction of NOx by CO and Hydrocarbons Over Different Catalysts in the Presence or Absence of O2

The performances of a non-noble metal (catalyst A), a non-noble metal catalyst containing a smaller amount of a noble metal (catalyst B) and noble metal (catalyst C) for NOx reduction at 400 - 600°C and space velocity of 16×10^-1h^-1 have been studied by means of a fixed-bed continuous flow system. In both the absence and presence of oxygen, the following activity orders of catalysts for the reduction of NOx to N₂ by CO and C₃H₆(HC) can be given: C > B > A and B > A C, respectively. Meanwhile, there was CO formation in the reduction reactions of NOx by HC on the three catalysts. The amount of CO produced on catalyst C was the largest of the three catalysts.     

汽车制造业资本结构的统计分析

利用2013-2015年三年来我国上市公司汽车制造业年报数据,运用描述统计、因子分析、回归分析得出汽车制造业资本结构的各项指标普遍表现出与一般合理区间的不同;分析得出了汽车制造业绩优企业资本结构的合理区间;分析得出了QR与企业业绩ROE之间是负相关,ALR与企业业绩ROE之间是正相关,ROA与企业业绩ROE之间是正相关,TAT与企业业绩ROE之间是正相关,LSA与企业业绩ROE之间是正相关.     

补贴退坡-双积分政策下两级供应链生产决策优化分析

在退坡与双积分政策下, 分析由一个车企和一个分销商组成的两级供应链中的生产决策问题。基于Stackelberg博弈, 阐释退坡和双积分对车企与分销商最优决策的影响。对比分析集中决策和分散决策对供应链绩效的影响, 帮助汽车供应链有效适应“双积分”政策。研究表明:在双积分政策未实施时, 随着补贴的不断降低, 新能源汽车的需求量、车企的利润会随之降低; 双积分政策实施之后, 车企不断提高研发努力水平可使新能源汽车的需求量提高, 车企与分销商的利润可获得帕累托改进。数值分析表明, 双积分政策可以有效促进新能源汽车的发展。     

Synthesis of a Novel High Solid Coating Used in Automobile

High solid coating is one of the most important environmental friendly coatings, and has been obtained great attention since 70s' last century. For there are high volatile organic compounds(VOCs) in the conventional coatings, which cause both a serious pollution and consume of a plentiful of natural resource, such as petroleum. The development and production of high solid coatings is pressing target for all the countries, especially for China due to our heavy population and short of resources. Based on the requirement, a novel coating with high solid content has been developed in our lab. The solid content of the resin is 80%, compared to the 55% of conversional resin. This coating is characterized by its unique molecular architecture, it is a kind of hyper-branched polymer with uniform distribution of the reactive groups along the molecular backbone, which can react with other chemicals to form a cross-linking structure at high temperature.The coating has a lower viscosity and lower Tg corresponding to its branched structure( scheme 1).This coating has been applied in the automobile finishing. The experimental results indicated that the developed coating presented high performance properties in fastness, mar resistance, and hardness, it also reduced the baking temperature, resulting in a energy saving.     

大尺寸工件视觉测量中的图像拼接方法

为提高大尺寸工件机器视觉测量精度,提出一种基于坐标变换的图像拼接方法,并给出该坐标变换方法的解算模型及求解方法,分析了局部测量误差、重叠区域公共点个数等对坐标变换精度的影响,得到了最佳拼接条件,并通过实验对其进行了验证。实验结果表明,该方法简单易行、结果可靠,对存在平移、旋转以及尺度缩放的图像都具有良好的效果,能有效地解决采用机器视觉进行大尺寸工件精确测量时的坐标归一化问题。     

Comparison of the Profiles of Polycyclic Aromatic Hydrocarbons in Different Areas of a City by Glass-Capillary-Gas-Chromatography in the Nanogram-Range

Since the PAH-mixture of different emittants such as coal heatings, oil heatings or gasoline engines are different and therefore characteristic, it is to be expected, that these PAH-profiles are helpful to recognize the main sources of an air pollution. Furthermore, this investigation compares the local concentrations of several selected PAH and records the temporary variation in PAH-profiles of different areas in a city during the year.

The collecting system consists of a low volume air sampler, connected with a glass fibre filter (490cm²). To separate the mixture of PAH glass-capillary-gas-chromoatography is used and 15 PAH are selected for this investigation (splitless injection, Silicone OV 17). The repeatability of the total collecting procedure and for the analysis is satisfactory.

Four areas have been selected inside the city: I. area with hand-stoked residential coal heatings, II. area with oil heatings preferentially, III. stations in a tunnel with automobile traffic, IV. area surrounding a coke plant.

The PAH-profiles differ in many cases from area to area and the concentrations of all PAH regarded (including benzo(a)pyrene) vary strongly during the day, week and year on the same place, even during the heating period for the 16 collecting stations investigated monthly (e.g. in case of BaP at the same place from 1.6 ng/m³ to 299 ng/m³).

Especially the distribution pattern of 4 PAH (BcPH, CYC, BghiP, COR) is completely different from the other PAH's recorded in the city. The first one correlates to the automobile traffic in the tunnel.