Processing and fiber content effects on the machinability of compression moulded random direction short GFRP composites

The random direction short Glass Fiber Reinforced Plastics (GFRP) have been prepared by two compression moulding processes, namely the Preform and Sheet Moulding Compound (SMC) processes. Cutting force analysis and surface characterization are conducted on the random direction short GFRPs with varying fiber contents (25∼40%). Edge trimming experiments are preformed using carbide inserts with varing the depth of cut and cutting speed. Machining characteristics of the Preform and SMC processed random direction short GFRPs are evaluated in terms of cutting forces, surface quality, and tool wear. It is found that composite primary processing and fiber contents are major contributing factors influencing the cutting force magnitudes and surface textures. The SMC composites show better surface finish over the Preform composites due to less delamination and fiber pullouts. Moreover, matrix damage and fiber protrusions at the machined edge are reduced by increasing fiber content in the random direction short GFRP composites.     

Analysis of neck fractures from frontal collisions at low speeds

Neck fracture is a major cause of death in traffic accidents. This pattern of injury normally occurs in a frontal collision or overturn of a vehicle. This study investigates the case of a neck fracture from a low-speed collision. In the examined case, the passenger in the front seat of the car fractured his neck and died. He did not have his seatbelt on when the vehicle slipped on a frozen road surface on a downward slope of a hill and impacted into the shoulder of the road at low speed. In this type of collision, an occupant’s body will be impacted by the windshield or other interior trim of the car. However, in this case, rather unusually, neither body tissue nor fiber remained although the collision involved a broken windshield. Thus, the reason for the passenger death was unidentified. This study applied the computer simulation package Madymo for analyzing the accident. The result of the simulation was that the passenger, who did not wear a seatbelt, moved forward due to inertia. The upper part of the passenger then rotated and lifted when the knee contacted with the dashboard. By evaluating the structural deformation of the vehicle at the front, we deduced that the collision velocity was 30 km/h. Through a computational experiment that was undertaken using Madymo 7.0, NIC was estimated to be 240 m²/s². This result far exceeded the threshold for neck injuries. In particular, in comparison with whiplash injuries, when the passenger’s head directly impacts the roof following a rear-end collision, the bending moment through hyperextension of the neck is greatly increased. In this study, we concluded that the manner of death was the hyperextension of the neck, as the passenger’s head contacted the roof from underneath.     

Low cost design of parallel parking assist system based on an ultrasonic sensor

This paper presents a low cost design and implementation of a parallel parking assist system (PPAS) based on ultrasonic sensors. Generally, a PPAS requires several types of sensors, such as an ultrasonic sensor, camera sensor, radar sensor and laser sensor for parking space detection. However, our proposed PPAS only requires two ultrasonic sensors on the front and lateral sides for parking space detection. Moreover, a steering angle sensor and wheel speed sensor installed in the vehicle are used to obtain vehicle position information for localization in ultrasonic range data. The hardware architecture of the PPAS based on an electronic control unit (ECU) module, sensor modules and a human machine interface (HMI) module was proposed. Moreover, the software architecture of the PPAS is based on system initialization, scheduling, recognition and a control algorithm. In particular, a novel sensor algorithm was proposed to minimize the vehicle corner error of the ultrasonic sensor. A prototype of the PPAS based on the proposed architecture was constructed. The experimental results demonstrate that the implemented prototype is robust and successfully performs parking space detection and automatic steering control. Finally, the low cost design and implementation of the PPAS was possible due to the cheap ultrasonic sensors, simple hardware design and low computational complexity of the proposed algorithm.     

Estimation of the adhesion force for a disc brake in a skid control condition

The performance of brakes has become important due to increased train speeds. The brake system of a train must possess a large brake force to stop the train safely within a limited stopping distance. However, an excessive brake force deteriorates the ride comfort and causes the train to skid. Therefore, it is necessary to control the brake force within the adhesion force limit. This paper presents an analytical method to estimate the relationship between the brake and adhesion forces of a disc brake system. This method has been applied to the actual disc braking control system of the Korea High-Speed Train (HSR350x), and the adhesion force is estimated in an actual skid condition.     

Digital human body model for seat comfort simulation

Using the recent anthropometry of the North American population, human body models were developed for seat comfort simulation. The external geometry of the models was acquired from the three-dimensional whole body laser scan of recruited volunteers in a driving position. The selection criteria for volunteers with standard size and shape were derived from a statistical factor analysis of the Size USA database. As a practical application of the model in a design process, comfortable driving postures were constructed by adopting the cascade prediction model (CPM), which takes into account both interior package layout and the driver’s anthropometry. The detail modeling process of finite element modeling and its validation results against volunteer measurements are introduced.     

����ͨӰ�������õ������ֵ���㼰�ؼ�ָ���о�

目前,区域交通影响评价相关工作处于理论探索阶段,其中作为前提和基础的区域用地面积阈值,已有初步研究方法如标准区域类比法. 以此为基础,本文对影响区域交评用地阈值的一些关键因素进一步梳理,确定了区域出行需求总量、机动车出行总量、土地利用混合率、区域道路网系统等影响因素. 以北京市为例,建立了研究区域用地阈值与标准区域用地阈值及关键因素的相关关系,以全市交通综合调查数据为依据,标定了标准区域面积阈值及关键因素指标,并通过案例分析描述如何在特定区域交通发展情况下确定合适的研究区域交评用地阈值,为以后研究工作提供借鉴.     

Switching service types for multi-region bus systems

Conventional fixed-route bus services are generally preferred to flexible-route services at high demand densities, and vice versa. This paper formulates the problem of integrating conventional and flexible services that connect a main terminal to multiple local regions over multiple time periods. The system’s vehicle size, route spacing (for conventional services), service area (for flexible services), headways and fleet sizes are jointly optimized to minimize the sum of supplier costs and user costs. The route spacing for conventional bus services and service area for flexible bus services are also optimized for each region. The proposed solution method, which uses a genetic algorithm and analytic optimization, finds good solutions quickly. Numerical examples and sensitivity analyses confirm that the single fleet variable-type bus service may outperform either the single fleet conventional bus service or the single fleet flexible bus service when demand densities vary substantially among regions and time periods.     

A method for measuring accurate traffic density by aerial photography

Traffic density can be accurately measured by counting the number of vehicles within 1 km; however, it is often calculated between macroscopic traffic parameters using the fundamental equation because of difficulty of observing traffic density directly in the field. Measuring density in this way may be inaccurate and may bias the analysis because the relationship between these traffic parameters can vary across the study sites. The purpose of this study is to find a method for measuring traffic density from aerial photography that is easy and accurate, and for this purpose, we investigated whether the measuring length (i.e., the length of a section of roadway from which observations of traffic are simultaneously collected) can be shorter than 1 km and yet retain the same measured traffic density. We divided an aerial photograph into several 20‐m unit sections, counted the number of vehicles manually, and examined measured traffic density according to central limit theory. According to the results of this study, with the number of 20‐m unit sections for observing traffic density at 15 (the measuring length is 300 m), the measured traffic density was almost the same as the density of a representative section of 1 km. Copyright © 2014 John Wiley & Sons, Ltd.     

Development of an IoT-based container tracking system for China’s Belt and Road (B&R) initiative

To ensure the successful implementation of China’s Belt and Road (B&R) Initiative, it is essential to enable the real-time monitoring of containers’ locations, prevent theft during cargo delivery, ensure more efficient logistics management and reduce carbon emissions. For this, it is vital to have an economic and effective system to track and control containers across multiple countries. However, this requirement cannot be met by today’s container tracking systems because they are either limited within the borders of each country or expensive to employ internationally. This study thus presents a framework for an IoT-based container tracking system that enables users not only to grasp the international flow of container movement with one check but also to achieve smooth cross-border procedures. To verify the system’s performance, an empirical test was made for an actual container shipped from Korea to Poland. The test results showed that the system could successfully track the location of the container in real time across international borders. Last, this study discusses the policy development and international cooperation that should take place to enable the introduction of this container tracking system.     

基于新记分函数与熵的犹豫中智VIKOR方法

针对犹豫中智信息的多属性决策问题,提出一种基于新记分函数与熵的VIKOR方法.首先,提出一种基于单值中智数的新记分函数,比较单值中智数的大小,通过与传统方法进行对比,验证该方法在区分度上要强于传统记分函数;其次,提出犹豫中智集熵的公理化定义,并构建犹豫中智熵的计算公式,证明了该公式满足公理化定义;提出基于犹豫中智熵的客观定权法,用于处理属性权重未知的多属性决策问题,可以有效解决定权问题;进而提出一种基于犹豫中智信息的VIKOR方法,对备选方案进行折衷排序.通过算例分析,并通过TOPSIS方法对比分析,验证了文中方法的有效性与合理性.