浅谈汽车生产一致性管理方法与实施策略

强制性产品认证实施规则的发布及实施是国家维护消费者权益的一项强有力的措施,汽车是强制性产品认证中重要的一个模块,本文主要结合企业对生产一致性管理、生产一致性控制计划的维护、COC证书、CCC标志、关键件符合性等控制措施的实施,从而保障企业的质量保障能力,达到五个一致,即公告车型、试验样品、车辆产品、产品合格证、出厂车辆上传信息的一致性。     

技能大赛视野下中职学校汽车专业核心课程教学改革与实践——以《电控发动机检修》课程为例

长期以来,中职学校汽车专业对于技能比赛存在着"重成绩、轻转化"的现象,导致只有少部分教师和学生受益,这与技能大赛"以赛促学、以赛促教、以赛促改"的理念相背。本文以《电控发动机检修》课程为例,阐述了中职学校汽车专业基于技能大赛开展专业核心课程教学改革策略与实践成效,以期为中职学校汽车专业核心课程教学改革提供有益借鉴。     

Compensation of pressure enthalpy effects on temperature fields for throttling of high-pressure real gas

For the pressure enthalpy of high pressure pneumatics, the computational fluid dynamics (CFD) simulation based on ideal gas assumption fails to obtain the real temperature information. Therefore, we propose a method to compensate the pressure enthalpy of throttling for CFD simulation based on ideal gas assumption. Firstly, the pressure enthalpy is calculated for the pressure range of 0.101 to 30 MPa and the temperature range of 190 to 298 K based on Soave-Redlich-Kwong (S-R-K) equation. Then, a polynomial fitting equation is applied to practical application in the above mentioned range. The basic idea of the compensation method is to convert the pressure enthalpy difference between inlet air and nodes into the compensation temperature. In the above temperature and pressure range, the compensated temperature is close to the real one, and the relative temperature drop error is below 10%. This error is mainly caused by the velocity difference of the orifice between the real and ideal gas models. Finally, this compensation method performs an icing analysis for practical high pressure slide pilot valve.     

郑西铁路客运专线黄土地基沉降控制技术研究

对郑州至西安客运专线Q2黏质黄土和Q3湿陷性砂质黄土的工后沉降控制技术进行了分析和研究,提出了合理、经济的地基沉降控制设计措施,为客运专线同类工程提供参考。     

混凝土路面施工中裂缝的成因及预防

介绍了混凝土路面形成裂缝的人为及环境、气候等主客观原因。     

空气弹簧对车辆曲线通过性能的影响

建立了考虑左右空气弹簧垂向耦合模型的车辆系统数学模型,由理想气体的状态方程得到空气弹簧的力学方程,分析了车辆通过曲线时车辆与空气弹簧的动态特性。仿真结果表明:由于高度阀的动作,车辆在驶出曲线后各空气弹簧的压力不一致,导致车体不能回到静平衡位置;车辆以正常速度通过曲线时,车辆曲线通过动力学性能变化不大;在车辆多次通过同一种曲线的较恶劣工况时,空气弹簧内气压变化范围是一定的;增加抗侧滚刚度能明显抑制车体侧滚,从而减小空气弹簧内气压的变化量;增大空气弹簧横向跨距,并选择合适的刚度和阻尼,能使车辆驶出曲线后各空气弹簧压力接近静平衡值。     

A signal-based fault detection and classification method for heavy haul wagons

This paper proposes a signal-based fault detection and isolation (FDI) system for heavy haul wagons considering the special requirements of low cost and robustness. The sensor network of the proposed system consists of just two accelerometers mounted on the front left and rear right of the carbody. Seven fault indicators (FIs) are proposed based on the cross-correlation analyses of the sensor-collected acceleration signals. Bolster spring fault conditions are focused on in this paper, including two different levels (small faults and moderate faults) and two locations (faults in the left and right bolster springs of the first bogie). A fully detailed dynamic model of a typical 40t axle load heavy haul wagon is developed to evaluate the deterioration of dynamic behaviour under proposed fault conditions and demonstrate the detectability of the proposed FDI method. Even though the fault conditions considered in this paper did not deteriorate the wagon dynamic behaviour dramatically, the proposed FIs show great sensitivity to the bolster spring faults. The most effective and efficient FIs are chosen for fault detection and classification. Analysis results indicate that it is possible to detect changes in bolster stiffness of ±25% and identify the fault location.     

5-羟色胺转运体基因多态性和抑郁症的发病、性别、严重程度及自杀行为的相关性

目的探讨中国汉族人群5-羟色胺转运体启动区(5-HTTLPR)基因多态性和抑郁症的发病、性别、严重程度及自杀是否相关。方法应用聚合酶链式反应(PCR)扩增技术测定150例抑郁症患者和150例正常对照者的5-HT-TLPR基因型和等位基因,分别验证各种基因型与中、重度抑郁症发病、性别及自杀行为的相关性。结果病例组SS、LS基因型及S等位基因频率均高于对照组(26.0% vs.20.0%;52.7% vs.46.0%;52.3% vs.43.0%;P均<0.05);两组性别分层比较,女性S等位基因频率高于对照组(55.3% vs.43.6%,P<0.05);病例组严重程度分层比较差异无统计学意义(P>0.05);病例组有无自杀行为分层比较,有自杀行为患者SS基因型频率(37.3% vs.20.2%)及S等位基因频率(61.8% vs.47.5%)均高于无自杀行为患者(P<0.05);抑郁自杀组性别分层比较未显示显著性差异(P>0.05);抑郁自杀组病情程度分层比较,重度抑郁自杀者SS基因型频率(42.5% vs.18.2%)及S等位基因频率(68.7% vs.36.4%)均高于中度抑郁自杀者(P<0.05)。结论在中国汉族人群中,5-HTTLPR多态性和抑郁症相关。S等位基因可能是抑郁症的易感基因,特别是女性,SS型可能是抑郁症易感基因型;S等位基因可能是抑郁症患者自杀的危险基因,SS基因型人群可能是抑郁症患者自杀的危险人群,特别是携带S等位基因的重度抑郁症患者更易自杀。     

Singular perturbation composite control of a free-floating flexible dual-arm space robot

The Free-floating Flexible Dual-arm Space Robot is a highly nonlinear and coupled dynamics system. In this paper, the dynamic model is derived of a Free-floating Flexible Dual-arm Space Robot holding a rigid payload. Furthermore, according to the singular perturbation method, the system is separated into a slow subsystem representing rigid body motion of the robot and a fast subsystem representing the flexible link dynamics. For the slow subsystem, based on the second method of Lyapunov, using simple quantitative bounds on the model uncertainties, a robust tracking controller design is used during the trajectory tracking phase. The optimal control method is designed in the fast subsystem to guarantee the exponential stability. With the combination of the two above, the system can track the expected trajectory accurately, even though with uncertainty in model parameters, and its flexible vibration gets suppressed, too. Finally, some simulation tests have been conducted to verify the effectiveness of the proposed methods.     

分布电容对舰船电力系统接地方式选择的影响

本文主要讨论分布电容对舰船电力系统接地方式选择的影响,分析了舰船电力系统在高电阻接地和谐振接地的方式下分布电容对系统的影响,发现在中压系统中大分布电容的情况下,采用高电阻接地会产生超过有关标准的故障电流。在谐振接地的情况下,需要合理的配置消弧线圈来产生感性电流来抵消系统对地电容产生的容性残流。同时依据具体数据,利用高斯定理对电缆电容进行了估算,与实际结果相吻合。