Comparison of PMP and DP in fuel cell hybrid vehicles

Pontryagin’s Minimum Principle (PMP) and Dynamic Programming (DP) are both from the optimal control theory and can both achieve optimal trajectories when they are applied to power management strategies of hybrid vehicles. However they have totally different control concepts. In order to select the superior one, the PMP-based and the DP-based power management strategies are introduced and compared for a fuel cell hybrid vehicle (FCHV) in this paper. The two power management strategies are applied to the FCHV in a computer simulation environment, and the simulation results from the two strategies are compared when the control variable for the PMP is fuel cell system (FCS) net power and for the DP is battery power. As a result, the superiority of the PMP-based power management strategy is proved.     

Future applications of Ni-Ti alloys in automotive safety systems

The shape memory alloys present unusual thermo-mechanical properties. The most important of them are pseudo-elasticity and memory effect. The paper investigates this behaviour for the Ni-Ti wires under static (v < 50 mm/s) and dynamic conditions (v > 50 mm/s) at different temperatures. Ni-Ti actuator and pseudoelastic wires with diameter between 0.1 mm to 0.5 mm are being tested. For dynamic investigation a new testing plant able to satisfy the testing conditions is created. This new testing plant is still under development and the reported results originate from the first tests on this new machine. The new device is designed to reach speeds higher than 50 mm/s. These speeds can be achieved using a drop weight which will hit a bottom plate and by this the kinetic energy is transferred to the sample. Because the weight is dropped, the stroke for the sample is measured in two points. The force of this impact will be in-line measured and, if the sample will be electrically activated during this test, it is also possible to log the electrical voltage. To widen the application range of the shape memory alloys it is necessary to study their behaviour in the dynamic region. With the new testing facility, it is expected to test the damping properties of SMA wires. In that case, these results can generate the basis for finding new applications for shape memory alloys especially in the automotive safety industry.     

Prediction procedure for wear distribution of transient rolling tire

As a research method, finite element analysis (FEA) with ABAQUS can help researchers to study throughout the whole process of abnormal tire wear. For precise tread wear simulation, this paper introduces a tire finite element model building method. Then, the model is verified by comparing its simulation results with experiment data. Based on the verified model, tire high-speed rolling procedure is presented by combining steady-state transport analysis and dynamic analysis. To predict the wear distribution, micro tread wear calculation method is described. Finally, the wear prediction procedure of tread mesh evolving is introduced and tire polygonal wear pattern is simulated by this procedure.     

Numerical modeling of hollow-cone fuel atomization,vaporization and wall impingement processes under high ambient temperatures

In the following paper, a numerical study of the atomization, vaporization and wall impingement processes of hollow-cone fuel spray from high-pressure swirl injectors under various ambient temperature conditions was carried out. Also, the availability of applied models and the effect of ambient temperature on spray characteristics is discussed. The Linearized Instability Sheet Atomization (LISA) model combined with the Aerodynamically Progressed Taylor Analogy Breakup (APTAB) model, the improved Abramzon model and the Gosman model are used to calculate the atomization, vaporization and wall impingement processes of hollow-cone fuel spray, respectively. Spray models are implemented with the modified KIVA code. The calculation results of the spray characteristics under two ambient temperatures, including spray tip penetration, spray structure and radial distance after spray-wall impingement are compared to the experimental results obtained by the Laser Induced Exciplex Fluorescence (LIEF) technique. The droplet size distribution, ambient gas velocity field, vapor phase distribution and fuel film mass generated by spray-wall impingement, measurements which are generally difficult to obtain by experimental methods, are also calculated and discussed. Quantitative discussions on the effect of the ambient temperature on the spray development process are conducted. It is shown that the applied models are applicable even in the high ambient temperature condition.     

Optimization and integration of ground vehicle systems

This article deals with the optimal design of ground vehicles and their subsystems, with particular reference to 'active' safety and comfort. A review of state-of-the-art optimization methods for solving vehicle system design problems, including the integration of electronic controls, is given, thus further encouraging the use of such methods as standard tools for automotive engineers. Particular attention is devoted to the class of methods pertaining to complex system design optimization, as well as approaches for the optimal design of complex systems under uncertainty. Some examples of design optimizations are given in the fields of vehicle system dynamics, powertrain/internal combustion engine design, active safety and ride comfort, vehicle system design and lightweight structures, advanced automotive electronics, and smart vehicles.     

Sliding mode observers for vehicle mode detection

This paper explores the use of sliding mode observers to detect the onset of potentially dangerous vehicle modes such as oversteer, understeer or split-μ braking. Provided these modes can be detected quickly enough, existing stability controllers can be engaged to ensure safe performance of the vehicle. It is shown that the equivalent output error injection signals associated with the sliding mode observer have distinctive signatures depending on the particular mode encountered. Appropriate thresholds on these signals can be set so the scheme ignores variations which arise during normal driving, but can detect and isolate different undesirable vehicle modes within 0.3 seconds of their onset.     

铁路噪声对沿线居民影响的研究

分析了铁路沿线居民对噪声的反应，并比较了铁路与交通运输噪声主观反应。结果表明，无论是高干扰率阈值的比较，或是从高干拢率与声级的回归方程比较，铁路和交通这两种运输噪声对人的主观反应干扰基本一样。     

Technical Note: Force Control in Electrohydraulic Active Suspensions Revisited

The inner loop control for the actuator force can be quite simply compensated by means of a correction term to the desired force signal at the input. The correction requires only a measurement of the actuator piston velocity and is employed to cancel the loop disturbance caused by the oil flow to the actuator. Although an additional time constant is introduced by the integration in the inner loop force control, the overall performance is nevertheless quite close to that of an ideal optimal system.     

Numerical Model of a Tilting Body Railway Vehicle Compared With Rig and on Track Tests

The aim of the paper is to describe and verify a numerical model for the simulation of the dynamic behaviour of a tilting body railway vehicle, with particular attention to the curve negotiation conditions. In the model the dynamics of the tilting active control devices are reproduced, combining the numerical mechanical model of the vehicle with the control software used on the real vehicle. In order to validate the numerical simulation model, numerical results and experimental ones, from both a test rig and out-door tests, were compared.