Enhanced selective forwarding scheme for alert message propagation in vehicular <Emphasis Type="Italic">ad hoc</Emphasis> networks

Vehicle-based applications were recently introduced to improve traffic safety and efficiency. These applications are classified into either safety-oriented or non-safety-oriented applications. Safety-oriented applications are typically provided by means of vehicle-to-vehicle (V2V) communications to support reliable and fast alert message propagation to all surrounding vehicles when an emergency occurs on the road. In vehicular ad-hoc network (VANET) broadcast-based packet forwarding is typically preferred for the propagation of urgent traffic-related information to all reachable nodes within a specified dangerous region. However, this approach may cause broadcast storm problems, which can lead to serious contention between transmissions from adjacent nodes. In this paper, we propose an alert message propagation scheme that is based on selective forwarding and aims to i) minimize the number of rebroadcasting nodes and ii) guarantee reliable and fast alert message delivery to all reachable nodes. Our scheme was evaluated using two different highway scenarios. The simulation results demonstrated that the performance of the proposed scheme was better than that of existing broadcast schemes in terms of the message delivery latency, the message delivery ratio, and the message rebroadcasting ratio.     

Optimization and design of disk-type MR brakes

In this paper, first a new design for a disk-type magneto-rheological (MR) brake for automotive applications is proposed and then, a finite element analysis is performed to analyze the resulting magnetic field intensity distribution within the MR brake configuration. This finite element model of the brake is then utilized in a optimization process which incorporates Genetic Algorithm (GA) to obtain optimal design parameters. The optimization process goal is to increase the braking torque capacity of the brake while keeping the weight of the brake as low as possible. Although, the braking torque of the present design is larger compared to the previous designs, the braking toque capacity of the present design is still smaller than the required braking torque for automobiles.     

Relationship between occupant injury and the perturbation mark on the velocity indicator on a cluster panel

A perturbation mark is occasionally produced on the velocity indicator of the cluster panel of a vehicle during a vehicle collision. This mark can be used to estimate the velocity of the vehicle at the moment of the vehicle’s impact. In this study, the effect of the impact velocity and the deceleration of the vehicle on the perturbation mark were investigated, and an analysis of the driver’s injury was also conducted through a numerical pulse representation and computer simulations. Sled and pendulum tests were used to replicate the conditions that produce a perturbation mark on the velocity indicator of a cluster panel. It was verified that a higher peak acceleration is more likely than the impact velocity to cause a perturbation mark. According to the computer simulation results, a driver’s injury could be more severe at higher peak accelerations with a constant impact velocity. If a perturbation mark, which can be used to estimate the impact velocity, is found while investigating a vehicle accident, this mark reveals that the acceleration was higher than that listed in the related crash report. Therefore, the injuries of the occupants could be more serious than those expected at the reported impact velocity.     

SS3型电力机车逻辑控制模块输出电路的设计与改进

逻辑控制模块（LogicControlModule,LCM）利用无触点的控制思想,能够克服继电器控制系统所存在的弊端,完全实现原有继电器系统的功能．本文针对SS3型电力机车逻辑控制模块的输出电路功率MOSFET经常烧坏的问题提出了设计和改进方案,并应用MATLAB仿真及实验论证．为SS3型电力机车无触点改造项目的研究,提供有利的经验和参考价值．     

基于广义回归神经网络与遗传算法的玻璃钢渔船船型要素优化研究

利用神经网络的非线性拟合能力,建立了基于广义回归神经网络的"船型要素-船体阻力"数学模型,提高了模型的拟合精度。同时结合遗传算法的非线性寻优能力,利用改进的遗传算法完成了船型要素的优化设计。优化结果可以作为玻璃钢渔船初步设计的技术参考。     

Technology analysis and low-cost design of automotive radar for adaptive cruise control system

Recently, the advanced driver assistance system (ADAS), which helps mitigate car accidents, has been developed using environmental detection sensors, such as long and short range radar, lidar, wide dynamic range cameras, ultrasonic sensors and laser scanners. Among these detection sensors, radars can quickly provide drivers with reliable information about the velocity, distance and direction of a target obstacle, as well as information about the vehicle in changing weather conditions. In the adaptive cruise control system (ACCS), three radar sensors are usually needed because two short range radars are used to detect objects in the adjacent lane and one long range radar is used to detect objects in-path. In this paper, low-cost radar based on a single sensor, which can detect objects in both the adjacent lane and in-path, is proposed for use in the ACCS. Before designing the proposed radar, we analyzed the world-wide radar technology and market trends for ACCS. Based on this analysis, we designed a novel radar sensor for the ACCS using radar components, such as an antenna, transceiver module, transceiver control module and signal processing algorithm. Finally, target detection experiments were conducted. In the experimental results, the proposed single radar can successfully complete the detection required for the ACCS. In the conclusion, the perspective and issues in the future development of the ACCS radar are described.     

Road profile input estimation in vehicle dynamics simulation

Vehicle motion simulation accuracy, such as in accident reconstruction or vehicle controllability analysis on real roads, can be obtained only if valid road profile and tire-road friction models are available. Regarding road profiles, a new method based on sliding mode observers has been developed and is compared with two inertial methods. Experimental results are shown and discussed to evaluate the robustness of our approach.     

A Variable Free Control Characteristic Vehicle

A variable characteristic car (VCC) has been developed at Melbourne University for driverlvehicle handling research. The vehicle is unusual in that it has facilities for varying both its fixed control and free control dynamic characteristics over wide ranges. In this paper the servo systems used to effect these changes are described. The calibration methods used to relate the vehicle response characteristics to the variable servo settings are detailed. Sample calibration results are given for the fixed control parameters steering ratio, yaw response time and stability factor. Calibration of the free control parameters is also described and results are given for the steering torque gradient, and the time-to-peak and percentage overshoot of the steering wheel motion in response to a step input of torque.     

Theoretical Analysis of a Semi Active Suspension Fitted to an Off-Road Vehicle

A theoretical analysis is presented to model a hydromechanical, semi-active suspension system, first as a single wheel station and then as fitted to each wheel of an off-road vehicle. Predicted results show that two benefits are obtained by comparison with the equivalent passive system. First, vehicle attitude is controlled for changes in body forces arising from static loads or braking/cornering inputs. Second, a significant improvement in ride comfort is obtained because low suspension stiffnesses can be used.     

Validation of Railway Vehicle Lateral Dynamics Models

The general form of the railway vehicle lateral dynamic predictions seems to have been proven. If wheels are coned, rails are of uniform cross-section, and suspensions are linear, then good predictions can be obtained. If wheels are not coned, and rail sections vary, but the suspension is relatively linear, as in modern vehicles, it is still possible to obtain good predictions of critical speed for flexible suspensions. The situation with “stiff” vehicles remains unproven. In each case dynamic response calculations will be only as good as the knowledge of the track input including the rolling line term. The validity of making calculations to predict critical speeds of very non-linear vehicles has not yet been convincingly demonstrated. Validation experiments for the more difficult case of time history representation suggest the possibility of correct prediction for easily comprehensible vehicles, but even this requires an enormous amount of supportive experimental work.