汽车可靠性强化试验技术的探讨

随着我国汽车工业的飞速发展，汽车产品的可靠性及保证其可靠性的技术日益受到人们的重视。为了优化可靠性试验技术，文章通过分析现有试验方法及其分类差异，总结了各方法的优点和缺点，从探讨汽车可靠性试验方法的经济性、有效性角度出发，提出了改进汽车可靠性试验工作的意见及相应措施，有效地缩短了汽车设计周期，提高了产品设计质量。     

浅谈水泥混凝土路面早期裂缝危害及分类防治

以本地区近年来新建的水泥混凝土路面为例,就其早期出现裂缝的原因、特点、分类及其危害进行了阐述,对如何防止和减少水泥混凝土路面早期裂缝提出了有效的对策.     

A study on scantling formulae of plate members due to lateral pressure under the effect of axial loads

Existing rule scantling formulae of plate members are based on conventional plastic design theory, and do not necessarily reflect complicated plate bending phenomena under axial loads. In this study, we first formulated the effect of axial load on the fully plastic moment based on the von Mises yield criterion for longitudinally stiffened plate in addition to the well-known formula for transversely stiffened plate. In addition, we derived a theoretical formulation of the lateral pressure corresponding to 2-point hinge and 3-point hinge formation taking account of the effect of the additional lateral force due to the axial loads on the deflected plating, using a simple plate strip bending model assuming a long plate with a large aspect ratio.Then, a series of elastic-plastic FE analyses was carried out to verify the structural behavior and the effect of axial load on the plate plastic bending strength. The plate strength was evaluated based on the residual deflection criteria of two cases (0.26 mm and 4.0 mm), and the results were compared with the theoretical derivation. As a result, it was found that assumption of linear strength reduction to the axial stress can cover the transversely stiffened plate under compressive axial stress conservatively. As to the transversely stiffened plate under tensile axial stress and the longitudinally stiffened plate, the strength reduction was in accordance with the reduction in the fully plastic moment based on the von Mises yield criterion in the conservative side. Finally, based on the findings, the required plate thickness coefficients were proposed on an empirical basis both for transversely and longitudinally stiffened plate under compressive and tensile axial loads.     

Exploring the feasibility of classification trees versus ordinal discrete choice models for analyzing crash severity

A cross-median crash (CMC) is one of the most severe types of crashes in which a vehicle crosses the median and sometimes collides with opposing traffic. A study of severity of CMCs in the state of Wisconsin was conducted by Lu et al. in 2010. Discrete choice models, namely ordinal logit and probit models were used to analyze factors related to the severity of CMCs. Separate models were developed for single and multi-vehicle CMCs. Although 25 different crash, roadway, and geometric variables were used, only 3 variables were found to be statistically significant which were alcohol usage, posted speed, and road conditions. The objective of this research was to explore the feasibility of GUIDE Classification Tree method to analyze the severity of CMCs to discover if any additional information could be revealed.A dataset of CMCs in the state of Wisconsin between 2001 and 2007, used in the study by Lu et al. was used to develop three different GUIDE Classification Trees. Additionally, the effects of variable types (continuous or discrete), misclassification costs, and tree pruning characteristics on models results were also explored. The results were directly compared with discrete choice models developed in the study by Lu et al. showing that the GUIDE Classification Trees revealed new variables (median width and traffic volume) that affect CMC severity and provided useful insight on the data. The results of this research suggest that the use of Classification Tree analysis should at least be considered in conjunction with regression-based crash models to better understand factors affecting crashes. Classification Tree models were able to reveal additional information about the dependent variable and offer advantages with respect to multicollinearity and variable redundancy issues.     

基于朴素贝叶斯分类器的水火弯板焰道点判定方法研究

针对现今造船业中水火弯板自动化加工难以确定焰道的现象,提出一种基于朴素贝叶斯分类器的水火弯板焰道点判定方法,旨在解决水火弯板焰道点的判定问题,进而辅助水火弯板焰道的生成。此方法通过经验参数和历史数据构建焰道点的朴素贝叶斯分类器,再利用构建的分类器对待测点进行类别概率计算,最后完成焰道点分类。实验表明,该判定方法对待测点的分类正确率高达87.4%,能够对焰道点进行有效分类判定。     

西攀路昔格达地层滑坡分析

因昔格达地层具有特殊的地质结构和物理力学性质,该地层中产生滑坡的密度在我国易滑地层中名列前茅。西攀路沿线广泛分布昔格达地层,通过西攀路昔格达地层基本特性的研究,对昔格达滑坡进行了分类,并对滑坡成因进行了分析。     

汽车发动机检测仪的分类及选用

汽车发动机检测仪是维修行业中广泛使用的一种汽车维修工具，目前市场上有几百个品种，因此维修企业必须根据企业的经济条件，操作对象以及维修项目等来挑选合适的检修仪，从检测仪的外形形式上看，可以分为台架式，便携式和袖珍式在种；从显示方式上可分为ＣＲＴ（阴极射线管）式，ＬＥＤ（发光二极管）或ＬＣＤ（液品）式和模拟仪表（指针仪表）式几种，从输入方式上可分为标准键盘式输入，波段开关输入和轻触键盘输入三种。     

基于动态时间弯曲的多模板匹配车型分类

针对环形感应线圈采集数据的特点,讨论一种基于动态时间弯曲(DTW)算法的车型分类新方法。由于采样波形与车速、车辆自身结构以及其通过线圈时的相对位置有关,导致实际同类车辆波形存在伸长、压缩,甚至波形残缺不全或局部振荡等复杂情况。为此,本方法首先对样本数据进行降噪滤波,补齐不完整信号等预处理;熟后结合DTW方法和最优聚类分析原理选取同类车型的多个模板,综合考虑误纳与误拒情况,可降低单模板匹配存在的误拒率;最后利用DTW算法和多个分类区分度指标进行多模板匹配,得出分类结论。论文仿真部分以一类车型为例,分析了本文方法与其他方法比较存在的优势。     

Surrounding Rock Classification of Banxi Group Slate with Abundant Water北大核心CSCD

For water-rich slate, surrounding rock argillization and softening is a serious problem. At present the uni-axial saturated compressive strength of rock is used as one of the indexes for classification of water-rich slate sur-rounding rock. Since Banxi Group slate has special geological characteristics, the above mentioned grading index is not completely suitable for its surrounding rock classification due to limitations. For this reason, using the Youfang-ping tunnel at the Changsha to Kunming Section of the Shanghai to Kunming high-speed railway in China as an ex-ample, a softening coefficient is introduced, and the underground water, rock mass integrity coefficient and angle of the main structural surface and tunnel axis are regarded as the main controlling factors. A system of surrounding rock classification for tunnels in water-rich slate is established. Based on the theory of fuzzy mathematics, the member-ship function of each index is structured and the weight of each index is calculated by AHP, and the grade of the sur-rounding rock is determined according to the maximum membership degree principle. The results show that the fuzzy information of surrounding rock classification is processed effectively and the classification of surrounding rock is achieved by qualitative analysis to quantitative evaluation by using fuzzy theory. The surrounding rock classification determined by introducing the softening coefficient on the basis of fuzzy theory is close to that determined in practical application, indicating that the practicability of this classification of tunnel surrounding rock in water-rich slate is high. This classification system therefore is a reference for the design and construction of tunnels in water-rich slate. © 2018, Editorial Office of "Modern Tunnelling Technology". All right reserved.     

对船检与海事管理中船舶分类的研究

比较船舶检验与海事管理中船舶分类的不同,提出应按照国家标准编制海事系统统一的船舶分类标准。