Improved hot-stamping analysis of tubular boron steel with direct measurement of heat convection coefficient

There are two types of hot-stamping processes, direct and indirect, depending on the sequence of the heating, forming, and quenching steps and the method used for each step. In this study, an indirect hot-stamping process consisting of forming at room temperature, heating, and water quenching was applied to develop a coupled torsion beam axle. The analysis results indicated that the application of the heat convection coefficient is critical in the simulations and must take into account the temperature and specific location in the model to ensure the accuracy of the heating and quenching analysis. The heat convection coefficients used in the analysis were directly measured at various positions of the tube (e.g., outside, inside, and bending region) using thermocouples, and the final values were determined through correlation between the actual tests and numerical analysis. The experimental and simulated final deformed shape and temperature distribution were in good agreement.     

Traffic-balancing algorithm for can systems with dual communication channels to enhance the network capacity

The controller area network (CAN) is the dominant protocol for in-vehicle network (IVN) systems because it provides bounded transmission delay among electronic control units (ECUs) at data rates between 100 Kbps and 1 Mbps. Many automotive companies have chosen the CAN protocol for their chassis network system of intelligent vehicles. However, the increasing number of ECUs in intelligent vehicles and the need for more intelligent functions require a network system with more network capacity and real-time capability. As one approach to enhance the network capacity of a CAN system, this paper introduces a CAN system with dual communication channels. This paper also presents a traffic-balancing algorithm that predicts the traffic of each channel and allocates frames to the most appropriate channel. An experimental testbed using commercial off-the-shelf microcontrollers with two CAN controllers was used to demonstrate the feasibility of the traffic-balancing algorithm.     

考虑引桥工作状态下的短跨板桥的车致动力反应

通过把车辆和桥梁看作一个耦合系统来建立模型去求解桥梁的车致动力反应。文中研究了由AASHTO HS20卡车引起的不同跨径的短板桥的动力反应。利用参数分析来研究不同车速及不同路面状况所产生的效应。研究发现,引起桥梁动力反应峰值的临界车速遵循描述列车致桥梁共振的规则。分析中考虑了引桥状态的影响包括引桥桥头断层及引桥板形变。虽然引桥变形对桥梁的动力反应影响微小,但是在研究中却发现引桥桥头断层能在短跨板桥中引起显著的动力反应。该文对评价既有短跨径桥梁的动力性能有很大的意义,因此值得中国从业者借鉴。     

热管--一种高效实用的散热方法

任何电子器件冷却的热电路都是由3个最基本的热阻组成的:结-壳热阻Rj-c;壳-散热器热阻Rc-s和散热器至周围介质的热阻Rs-a.为降低这些热阻的临界值,许多工程师费尽心血.文章讨论采用热管有助于降低热阻Rs-a至最小值.散热器至周围介质的热阻是由传导、对流/辐射和被加热的冷却介质形成的3个热阻组成的.典型的风冷散热器中,空气温升的热阻是通风量的直接函数,对流热阻是散热表面积的函数,传导热阻是散热器材料的热导率和几何尺寸的函数.热管能把传导损耗降至最小值,它允许加大散热表面,而且使给定风速下的流量最大,从而有效降低散热器的3个主热阻.文章讨论了能降低风冷散热器热阻的热管.     

An overview of biodiesel in Asian countries and the harmonization of quality standards

Recently, biofuels have been actively introduced as transportation fuels in Asian countries. Common drivers to use biofuels are energy security, fuel diversification, and the reduction of greenhouse gases. In addition, some Southeastern Asian countries look forward to utilizing the abundant agricultural resources and providing stability for farmers. However, a compromised quality of biofuels could cause vehicle trouble, which is why the quality standard of the fuels is very important. On the other hand, the quality standard of biofuels differs from country to country and could cause vehicle trouble in some countries and not others. These differing standards may become an obstacle to trade. In this situation, the harmonization of the biodiesel standards in the East Asia Summit (EAS) region has been initiated by the ERIA biodiesel working group, in which members are the specialists from each country. This review summarizes the introduction of biofuels in this region and the recent activities regarding the harmonization of the fuel quality standard. Important background for this review is based on the results of the ERIA biodiesel working group meeting.     

Robust design optimization of suspension system by using target cascading method

This study presents the robust design optimization process of suspension system for improving vehicle dynamic performance (ride comfort, handling stability). The proposed design method is so called target cascading method where the design target of the system is cascaded from a vehicle level to a suspension system level. To formalize the proposed method in the view of design process, the design problem structure of suspension system is defined as a (hierarchical) multilevel design optimization, and the design problem for each level is solved using the robust design optimization technique based on a meta-model. Then, In order to verify the proposed design concept, it designed suspension system. For the vehicle level, 44 random variables with 3% of coefficient of variance (COV) were selected and the proposed design process solved the problem by using only 88 exact analyses that included 49 analyses for the initial meta-model and 39 analyses for SAO. For the suspension level, 54 random variables with 10% of COV were selected and the optimal designs solved the problem by using only 168 exact analyses for the front suspension system. Furthermore, 73 random variables with 10% of COV were selected and optimal designs solved the problem by using only 252 exact analyses for the rear suspension system. In order to compare the vehicle dynamic performance between the optimal design model and the initial design model, the ride comfort and the handling stability was analyzed and found to be improved by 16% and by 37%, respectively. This result proves that the suggested design method of suspension system is effective and systematic.     

Four-wheel vehicle kinematic and geometric constraints for definition of tire slip angle

When considering vehicle safety, tires and all that they represent are a fundamental topic. Tire studies have received a considerable amount of attention from the research community because their improvement has a direct and strong impact on vehicle handling and braking. Within this eld of analysis lies an important behavioral feature: the tire slip angle, which is a consequence of lateral forces acting on the tire. This characteristic is predicted in some cases and evaluated experimentally in others. This paper addresses another way to assess the slip angle. We propose a mathematical model that describes a constraint linking the slip angle and steering angle that make a vehicle turn. We present a simplied kinematic model (based on the classic bicycle model) and a four-wheel model, which makes all of the angles involved compatible with each other. In our case, the match will be given by the determination of the turning radius. Two different scenarios, understeering and oversteering vehicles, were simulated, and the results and conclusions reached are presented herein.     

SCR control strategy based on ANNs and Fuzzy PID in a heavy-duty diesel engine

The paper presents an innovative method combining artificial neural networks (ANNs) with Fuzzy PID to demonstrate the advantages of this control approach for meeting both NOx emission requirements and NH3 slip targets. An ANN model was utilized to simulate the formation of NOx emissions under various engine operating conditions. Next, an effective closed-loop control strategy with a type of feedback known as fuzzy PID is adopted for on-line, real-time control of 32.5% aqueous urea dosing in the exhaust stream. The new strategy explores the benefits by simulation and testing in the environments of Matlab/Simulink and ESC/ETC, respectively. The notable achievement of considerable NOx reduction and an acceptably small NH3 slip is obtained based on this new, feasible and effective strategy.     

Adaptive neural network based fuzzy control for a smart idle stop and go vehicle control system

Idle stop and go (ISG) is a low cost but very effective technology to improve fuel efficiency and reduce engine emissions by preventing unnecessary engine idling. In this study, a new method is developed to improve the performance of conventional ISG by monitoring traffic conditions. To estimate frontal traffic conditions, an ultra-sonic ranging sensor is employed. Several fuzzy logic algorithms are developed to determine whether the engine idling is on or off. The algorithms are evaluated experimentally using various data gathered in real areas with traffic congestion. The evaluation results show that the method developed can reduce the chance of false application of ISG significantly while improving fuel efficiency up to 15%.     

Modelling and validation of coupled high-speed maglev train-and-viaduct systems considering support flexibility

This study presents a more realistic modelling of the maglev-based high-speed railway line in Shanghai, China. Focus is placed on an accurate simulation of the two subsystems: the train subsystem including the magnets and the viaduct subsystem including the modular function units of the rails. The electromagnet force–air gap model with a proportional-derivative (PD) controller is adopted to simulate the interaction between the maglev train via its electromagnets and the viaduct via its modular function units. The flexibilities of the rails, girders, piers and associated elastic bearings are all considered in the modelling of the viaduct subsystem to investigate their effects on an interaction between the two subsystems. By applying the proposed model to the Shanghai maglev line, the essential characteristics of the coupled system can be duly captured. The accuracy and effectiveness of the proposed approach are then validated by comparing the computed dynamic responses and frequencies with the measurement results. It is confirmed that the proposed modelling with a detailed simulation of the magnets and modular function units can duly account for the dynamic interaction between the train and viaduct systems. Moreover, the effects of the inclusion of the flexibilities of the rails, girders and elastic supports to the response of the coupled system are respectively investigated, the results of which prove that their involvements are essential to the accurate prediction of the response of the coupled maglev train–viaduct system.