Analysis of vehicle emission measurements on the new WLTC,the NEDC and the CADC

Several studies have shown that the type-approval data is not representative for real-world usage. Consequently, the emissions and fuel consumption of the vehicles are underestimated. Aiming at a more dynamic and worldwide harmonised test cycle, the new Worldwide Light-duty Test Cycle is being developed. To analyse the new cycle, we have studied emission results of a test programme of six vehicles on the test cycles WLTC (Worldwide Light-duty Test Cycle), NEDC (New European Driving Cycle) and CADC (Common Artemis Driving Cycle). This paper presents the results of that analysis using two different approaches. The analysis shows that the new driving cycle needs to exhibit realistic warm-up procedures to demonstrate that aftertreatment systems will operate effectively in real service; the first trip of the test cycle could have an important contribution to the total emissions depending on the length of the trip; and that there are some areas in the acceleration vs. vehicle speed map of the new WLTC that are not completely filled, especially between 70 and 110 km/h. For certain vehicles, this has a significant effect on total emissions when comparing this to the CADC.     

Exact and meta-heuristic approach for a general heterogeneous dial-a-ride problem with multiple depots

Dial-a-ride problems are concerned with the design of efficient vehicle routes for transporting individual persons from specific origin to specific destination locations. In real-life this operational planning problem is often complicated by several factors. Users may have special requirements (e.g. to be transported in a wheelchair) while service providers operate a heterogeneous fleet of vehicles from multiple depots in their service area. In this paper, a general dial-a-ride problem in which these three real-life aspects may simultaneously be taken into account is introduced: the Multi-Depot Heterogeneous Dial-A-Ride Problem (MD-H-DARP). Both a three- and two-index formulation are discussed. A branch-and-cut algorithm for the standard dial-a-ride problem is adapted to exactly solve small problem instances of the MD-H-DARP. To be able to solve larger problem instances, a new deterministic annealing meta-heuristic is proposed. Extensive numerical experiments are presented on different sets of benchmark instances for the homogeneous and the heterogeneous single depot dial-a-ride problem. Instances for the MD-H-DARP are introduced as well. The branch-and-cut algorithm provides considerably better results than an existing algorithm which uses a less compact formulation. All seven previously unsolved benchmark instances for the heterogeneous dial-a-ride problem could be solved to optimality within a matter of seconds. While computation times of the exact algorithm increase drastically with problem size, the proposed meta-heuristic algorithm provides near-optimal solutions within limited computation time for all instances. Several best known solutions for unsolved instances are improved and the algorithm clearly outperforms current state-of-the-art heuristics for the homogeneous and heterogeneous dial-a-ride problem, both in terms of solution quality and computation time.     

汽车消声器内部压力预测方法研究

消声器内部压力脉冲是造成辐射噪声的主要原因之一,因此预测内部压力对研究消声器辐射噪声具有意义.采用GT-Power软件建立汽车发动机和消声器一维模型,从而进行仿真分析,预测消声器内部压力时序值;通过Matlab软件DFT变换对其压力时序值进行频谱分析,得到了压力频域值.通过与试验对比,验证了仿真模型预测压力时序值的准确性和预测压力频域值的有效性.     

浅析美军中型战术车辆的发展

世界整体格局及战争型式不断变化,未来战争对中型战术车辆的要求也在不断变化,为适应未来战争的需求,中型战术车辆的未来发展路线也需要不断的探索和研究.     

The interurban DRAG-Spain model: The main factors of influence on road accidents in Spain

This paper presents the results of applying DRAG methodology to the identification of the main factors of influence on the number of injury and fatal accidents occurring on Spain’s interurban network. Nineteen independent variables have been included in the model grouped together under ten categories: exposure, infrastructure, weather, drivers, economic variables, vehicle stock, surveillance, speed and legislative measures. Highly interesting conclusions can be reached from the results on the basis of the different effects of a single variable on each of the accident types according to severity. The greatest influence revealed by the results is exposure, which together with inexperienced drivers, speed and an ageing vehicle stock, have a negative effect, while the increased surveillance on roads, the improvement in the technological features of vehicles and the proportion of high capacity networks have a positive effect, since the results obtained show a significant drop in accidents.     

汽车助力转向系统异响问题分析研究

以某A0级轿车助力转向系统为研究对象,阐述了排查汽车转向系统异响问题的一般方法,之后对转向系统内关键部件的结构进行了分析,最后对各关键部件异响的形成机理进行了研究,形成了分析排查电动转向系统异响的一般流程,具有一定的参考意义。     

Software-in-the-loop development and validation of a Cornering Brake Control logic

In this article, a logic for vehicle dynamics control during partial braking while turning a corner is presented, which only requires knowledge of the instantaneous speed of the four wheels. For this reason, the proposed control algorithm can be adopted on all ABS equipped cars. A scheme of the simulation program for logic validation is described, which is constituted by a loop of software models of the principal vehicle subsystems which are singly illustrated. The proposed logic has been tested both in closed and open-loop maneuvers. The results are provided in the form of time histories of the principal analyzed quantities. The analysis of the results confirms the goodness of the proposed control strategy.     

芜湖长江大桥裕溪河桥车桥耦合振动分析

采用空间杆系有限元方法,建立芜湖长江大桥裕溪河2×80 m连续钢桁梁桥的动力分析模型。计算得到其横向基频为2.097 Hz,与实测值1.95 Hz吻合良好,且满足现行《铁路桥梁检定规范》相应限值1.125Hz的要求。运用车桥空间耦合振动理论对该桥在实际运营列车作用下的车桥动力响应进行计算与分析,结果表明,在空载及空重混编货物列车以速度50~80 km.h-1通过时,桥梁的横向振幅达到4.5~8.1 mm,与实测值4.6~8.4 mm吻合良好,但超出《铁路桥梁检定规范》的限值,而脱轨系数小于0.8,轮重减载率小于0.6;当通过速度在70 km.h-1以下时,机车车辆平稳性达到“良”或“合格”。因此,该桥能够满足空载及空重混编货物列车以70 km.h-1及以下速度通过。     

Modeling techniques for periodic vehicle routing problems

This paper presents a continuous approximation model for the period vehicle routing problem with service choice (PVRP-SC). The PVRP-SC is a variant of the period vehicle routing problem in which the visit frequency to nodes is a decision of the model. This variation can result in more efficient vehicle tours and/or greater service benefit to customers. We present a continuous approximation model to facilitate strategic and tactical planning of periodic distribution systems and evaluate the value of service choice. Further, results from the continuous model can provide guidelines for constructing solutions to the discrete PVRP-SC.     

Large motion mountain biking dynamics

A bond graph model of a mountain bike and rider is created to develop baseline predictions for the performance of mountain bikes during large excursion maneuvers such as drops, jumps, crashes and rough terrain riding. The model assumes planar dynamics, a hard-tail (front suspension only) bicycle and a rider fixed to the bicycle. An algorithm is developed to allow tracking of a virtual tire-ground contact point for events that separate the wheels from the ground. This model would be most applicable to novice mountain bikers who maintain a nearly rigid relationship between their body and the bicycle as opposed to experienced riders who are versed in controlling the bicycle independent of the body. Simulations of a steep drop are performed for various initial conditions to qualitatively validate the predictions of the model. Results from this model are to be compared to experimental data and more complex models in later research, particularly models including a separate rider. The overarching goals of the research are to examine and understand the dynamics and control of interactions between a cyclist and mountain bike. Specific goals are to understand the improvement in performance afforded by an experienced rider, to hypothesize human control algorithms that allow riders to perform manoeuvres well and safely, to predict structural bike and body forces from these maneuvers and to quantify performance differences between hard-tail and full suspension bicycles.