构建转基因食品安全评价新体系

通过对我国转基因食品发展状况的分析,以及转基因食品管理制度体系的不足的评述,并由此引发了笔者对于构建转基因食品新安全评价体系的思考。文中将政府作为架构责任主体,为构建多层次、全方位的新安全评价体系提出了一些可行性措施。     

长三角港口竞合期待破局

“从上海到南京392公里之内,居然有南京、扬州、泰州、镇江、常州、江阴、张家港、南通、常熟、太仓10多个港口,平均39公里一个,长江沿岸港口密度之大,无形中造成船舶靠港频繁、影响班期状况。”谈起长三角水网地区密布的港口,中海集运调度中心总经理吴亚春颇有微词。他希望政府管理部门能对此关注。“十一五”的到来,让长三角港口的新一轮竞争烽烟再起,港口的发展,究竟是市场自然发育,还是靠政府宏观调控,个中尺度颇难把握。年初刚刚履新的上海组合港管理委员会办公室主任王明志,把貌合神离的两省一市的港口当家人们按到一张餐桌上,研究在合作与竞争这两道菜式上究竟如何下箸。     

建立油污损害赔偿基金是当务之急

随着航运业的快速发展,船舶污染事故给海洋环境带来的潜在威胁越来越大。在“2005年上海国际海事论坛”上事关石油货主和承运人利益的“油污损害赔偿基金”成为本次论坛的主题。船舶溢油事故风险在增大因海上交通事故而引发大规模石油污染的可能性随着石油运输量的猛增而上升。     

洋山:让上海港如虎添翼

在我国这样一个市场巨大、腹地辽阔的国家,特别是长三角地区,如果没有一个国际航运中心,在国际分工与竞争中就会处于被动地位。近百年内天然水深都将保持在15米左右的洋山深水港,不仅能从容接纳当前世界上最大型的8500标箱集装箱船,也能满足明年出现的吃水14.5米的万箱“巨无霸”集装箱船的停泊,是上海竞争国际航运中心打出的一张“王牌”。刚刚开港的洋山深水港区是本年度上海向国际航运界献上的又一份大礼。     

谈国际上对第三方船舶管理业务范围的理解

随着中国加入世贸、中国经济的快速稳定发展、IT技术的迅速发展,以及越来越多的国际航运法规的产生,进入专业船舶管理行业的门槛越来越高。通过研究和分析,使我国的第三方船舶管理在专业船舶管理的规范化、专业船舶管理的技术、专业船舶管理的市场开发、专业船舶管理的法律、船舶管理公司的地理布局优化、船舶管理公司整合兼并收购以及船舶管理公司战略问题及相关工作得到解决和提高。     

Analysis of the car body stability performance after coupler jack-knifing during braking

This paper aims to improve car body stability performance by optimising locomotive parameters when coupler jack-knifing occurs during braking. In order to prevent car body instability behaviour caused by coupler jack-knifing, a multi-locomotive simulation model and a series of field braking tests are developed to analyse the influence of the secondary suspension and the secondary lateral stopper on the car body stability performance during braking. According to simulation and test results, increasing secondary lateral stiffness contributes to limit car body yaw angle during braking. However, it seriously affects the dynamic performance of the locomotive. For the secondary lateral stopper, its lateral stiffness and free clearance have a significant influence on improving the car body stability capacity, and have less effect on the dynamic performance of the locomotive. An optimised measure was proposed and adopted on the test locomotive. For the optimised locomotive, the lateral stiffness of secondary lateral stopper is increased to 7875?kN/m, while its free clearance is decreased to 10?mm. The optimised locomotive has excellent dynamic and safety performance. Comparing with the original locomotive, the maximum car body yaw angle and coupler rotation angle of the optimised locomotive were reduced by 59.25% and 53.19%, respectively, according to the practical application. The maximum derailment coefficient was 0.32, and the maximum wheelset lateral force was 39.5?kN. Hence, reasonable parameters of secondary lateral stopper can improve the car body stability capacity and the running safety of the heavy haul locomotive.     

A vehicle stability control strategy with adaptive neural network sliding mode theory based on system uncertainty approximation

Modelling uncertainty, parameter variation and unknown external disturbance are the major concerns in the development of an advanced controller for vehicle stability at the limits of handling. Sliding mode control (SMC) method has proved to be robust against parameter variation and unknown external disturbance with satisfactory tracking performance. But modelling uncertainty, such as errors caused in model simplification, is inevitable in model-based controller design, resulting in lowered control quality. The adaptive radial basis function network (ARBFN) can effectively improve the control performance against large system uncertainty by learning to approximate arbitrary nonlinear functions and ensure the global asymptotic stability of the closed-loop system. In this paper, a novel vehicle dynamics stability control strategy is proposed using the adaptive radial basis function network sliding mode control (ARBFN-SMC) to learn system uncertainty and eliminate its adverse effects. This strategy adopts a hierarchical control structure which consists of reference model layer, yaw moment control layer, braking torque allocation layer and executive layer. Co-simulation using MATLAB/Simulink and AMESim is conducted on a verified 15-DOF nonlinear vehicle system model with the integrated-electro-hydraulic brake system (I-EHB) actuator in a Sine With Dwell manoeuvre. The simulation results show that ARBFN-SMC scheme exhibits superior stability and tracking performance in different running conditions compared with SMC scheme.     

卡车传动轴总成强度仿真分析

传动轴作为卡车传递动力的主要部件,在装配到整车之前的设计阶段就必须对其进行反复矫验,以保证其使用可靠性。本文基于HyperWorks的Abaqus模板对传动轴使用状态进行了仿真模拟,提出了传动轴强度分析的方法。通过对该方法进行试验验证,结果表明这种方法预测传动轴的强度是比较可靠的.它可以减少试验次数并有效的缩短产品开发效率。     

Emergency steering control of autonomous vehicle for collision avoidance and stabilisation

ABSTRACT

Collision avoidance and stabilisation are two of the most crucial concerns when an autonomous vehicle finds itself in emergency situations, which usually occur in a short time horizon and require large actuator inputs, together with highly nonlinear tyre cornering response. In order to avoid collision while stabilising autonomous vehicle under dynamic driving situations at handling limits, this paper proposes a novel emergency steering control strategy based on hierarchical control architecture consisting of decision-making layer and motion control layer. In decision-making layer, a dynamic threat assessment model continuously evaluates the risk associated with collision and destabilisation, and a path planner based on kinematics and dynamics of vehicle system determines a collision-free path when it suddenly encounters emergency scenarios. In motion control layer, a lateral motion controller considering nonlinearity of tyre cornering response and unknown external disturbance is designed using tyre lateral force estimation-based backstepping sliding-mode control to track a collision-free path, and to ensure the robustness and stability of the closed-loop system. Both simulation and experiment results show that the proposed control scheme can effectively perform an emergency collision avoidance manoeuvre while maintaining the stability of autonomous vehicle in different running conditions.     

如何减少轮毂基准面装夹反弹

摩托车轮毂作为大直径类零件,并且整体结构刚性相对比较单薄,在经过机械车加工装夹后,易发生基准面变形反弹,从而影响零件尺寸和形位公差.通过车床夹具设计改进,减少零件基准面与夹具的接触面积,从而消除基准面不平造成的装夹反弹.