汽车防抱死制动系统性能的研究

汽车防抱死制动系统的性能直接关系到汽车的运行安全,笔者以获得汽车制动最佳效能并能自动适应路况变化为控制系统的设计目标;通过分析车轮制动的动力学原理;运用自寻最优控制理论;进行了基于路面附着系数的汽车防抱死制动系统设计.仿真实验结果表明:该控制系统能充分利用最大附着力制动、实现自动路面识别并可提高汽车制动时的操作稳定性;进而证实了基于路面附着系数的汽车防抱死制动自寻最优控制方法,相对以往的控制方法更为简单和更适合于实际应用.     

汽车制动性动态测试装置设计及仿真分析

分析了汽车制动系统的技术要求和制动性能检测指标,及现有的制动性能检测方法和检测设备存在的问题,然后提出了动态检测系统的设计构想,并在理论上建立了汽车在该系统下制动时的动力学模型,用Matlab对该模型进行仿真,进一步说明在进行汽车制动性能检测时应检测汽车的动态轴重而非静态轴重,为汽车制动性能检测提供充分的理论依据。     

滚筒式制动试验台检验能力的比对试验及评价

制动性能是机动车安全技术性能检验工作中的重要项目,多采用滚筒反力式制动试验台.该种台试检验方法的评价指标较多,重复性不好,且影响检测结果的因素各异,因此其检验能力的比对试验及评价困难.通过比对试验的实施,讨论确定了进行比对的检测参量,分析了车辆技术状况变化对比对的影响.然后,分别采用经典统计法和稳健统计Z比分数方法对滚筒台式制动性能比对试验数据进行处理,对计算结果进行了分析讨论,并就结果的评价问题进行了进一步的探讨.本研究有助于促进和提升机动车安全技术检验机构的检验工作,对于保障道路交通安全具有积极地意义.     

A new approach to the estimation of the probable number of fatalities in accidental explosions

This paper presents a new methodology for estimating the probable number of fatalities in accidental explosions in fixed installations, as a function of the amount of the flammable substance involved. A review of the procedure proposed by Marshall (1977) (Marshall, V.C., 1977 How lethal are explosions and toxic escapes? The Chemical Engineer, August 1977, 573–577). reveals its limitations, given the great dispersion of ungrouped data. The proposed alternative enables the estimation of the maximum probable number of fatalities and the percentage of cases in which a certain number of fatalities is reached, based on the knowledge of the amount of material presumably involved and through the application of the historical analysis of accidents. It must be pointed out that the proposed method considers not only fatalities derived directly from the overpressure wave but also those due to thermal radiation or missile impact.     

Fatal accidents in nighttime vs. daytime highway construction work zones

INTRODUCTION: Awareness about worker safety in nighttime construction has been a major concern because it is believed that nighttime construction creates hazardous work conditions. However, only a few studies provide valuable comparative information about accident characteristics of nighttime and daytime highway construction activities. METHOD: This study investigates fatal accidents that occurred in Illinois highway work zones in the period 1996-2001 in order to determine the safety differences between nighttime and daytime highway construction. The lighting and weather conditions were included into the study as control parameters to see their effects on the frequency of fatal accidents occurring in work zones. RESULTS: According to this study, there is evidence that nighttime construction is more hazardous than daytime construction. The inclusion of a weather parameter into the analysis has limited effect on this finding. IMPACT ON INDUSTRY: The study justifies establishing an efficient work zone accident reporting system and taking all necessary measures to enhance safety in nighttime work zones.     

Differences in relative risks for fatal occupational highway transportation accidents

Problem and Method: This study examined the trends in the relative risks for being involved in fatal occupational highway transportation accidents based upon the age and gender of the victim. Results: Significant differences in relative risks were identified based upon age; however, there were no significant differences in relative risks based upon gender. The trend analysis of relative risks for all motor-vehicle accidents based upon age showed that males exhibited a significant cubic trend while females exhibited a significant linear trend. The trend analysis of relative risks for fatal motor-vehicle accidents specifically involving vehicle operators based upon age yielded a significant quadratic trend for males and no significant trends for females. Examining the relative risks for fatalities involving only motor-vehicle operators controlled, to a certain extent, the differences in job exposure to motor-vehicle accidents based upon age. Impact: Prevention measures are identified as most crucial for older male workers in the transportation and agriculture industries.     

Epidemiology of subway-related fatalities in New York City, 1990-2003

Problem

Subway transit is a relatively safe mode of transportation, yet compared to all other forms of mass transit in the United States (U.S.), subways have the highest fatality rate. The aim of this paper is to characterize subway-related fatalities in order to identify opportunities for risk reduction.

Method

Medical examiner records for all New York City (NYC) subway-related deaths (1990-2003) were reviewed. Data were abstracted on decedents' demographics and autopsy findings, including laboratory findings.

Results

There were 668 subway-related fatalities, of these, 10 (1.5%) were homicides, 343 (51.3%) were determined to be suicides, and 315 (47.2%) were accidental. Although decedent characteristics varied between fatality categories, they were not particularly informative with regard to prevention.

Conclusion

Prevention strategies that focus on structural controls are likely to be most efficacious in improving the overall safety of the NYC subway systems.

Impact on industry

These findings suggest that structural rather than individual-level interventions would be most successful in preventing subway fatalities.     

Occupational accidents with ladders in Spain: Risk factors

Introduction

Occupational accidents suffered by workers in Spain when using ladders were analyzed over a six year period from 2003-2008, during which the total of notified ladder-related accidents amounted to 21,725. Method: Different accident-related factors were identified for the purpose of developing a pattern of those factors that had the greatest influence on the seriousness and the fatality of such accidents. Thus, a series of variables were examined such as age and length of service of the injured worker, firm size, the work sector, the injury suffered, and the part of the body that was injured. Since falls is the most frequent and most serious of ladder related occupational accidents, a special analysis of falls was performed. Results: The findings showed that the seriousness of ladder-related accidents increased with the age of the injured worker. Likewise, accidents at places other than the usual workplace were more serious and registered higher fatalities than those that occurred at the usual place of work. Conclusions: The analysis of falls from ladders established that accidents in smaller-sized firms were of greater seriousness and involved more fatalities than those in larger-sized firms. The investigation also underlined the need for stricter compliance with preliminary safety assessments when working with ladders.     

汽车辅助制动装置发展综述

平均行驶速度和载重量的增加,要求车辆具有更大的制动效能,为了有效分流制动负荷常采用辅助制动系统.介绍国内外制动法规的发展和现状,排气辅助制动装置、发动机缓速器、电涡流缓速器和液力缓速器的结构、工作原理及各辅助制动装置的制动性能;比较各辅助制动装置的优缺点,有利于汽车制动技术的发展,全面提高汽车行驶安全性能;展望未来汽车辅助制动装置的两大发展趋势,一是电子控制技术在汽车制动上的应用,二是多种辅助制动装置的联合制动.     

An investigation of lifting operations on UK construction sites

Lifting operations and associated equipment have become commonplace within the UK construction industry. However, recent high profile accidents involving lifting equipment have shown that the result of its misuse can have serious cost and health implications.The main aim of the research was to investigate lifting operations on construction sites exploring different options, their effectiveness, and their effect on safety. This research looked into the processes in place; the factors that have to be taken into consideration when placing and using lifting equipment; and the competent persons required when operating equipment. With these aims, literature review was conducted. This was followed by investigation on three construction sites. These case studies were enhanced through interviews with general site staff, managerial staff, and appointed persons.The findings revealed six main points to improve safety in lifting operations. These are: through planning; training; equipment selection, use and inspection; feedback/communication; appointed person’s role; and database. Thorough planning of lifting operations has positive effects on safety. There is need for tighter accreditation of all qualifications in the lifting operations field. The charter of major lifting equipment from specialist contractors should be considered as industry best practise. Companies should avoid authoritarian working culture to facilitate efficient feedback to improve safety. The appointed person should have site based role. Site inspections and maintenance should be monitored on a national database form.Practitioners can benefit from this paper as it provides information on experiences from three construction sites. Furthermore, researchers can use the findings for their future studies.     

重载铁路长大下坡曲线段列车行车安全性分析

为保障重载铁路长大坡道曲线地段的行车安全,以车钩摆角、脱轨系数、轮轨横向力、轮重减载率、车轮表面疲劳指数、轮轨磨耗指数为评价指标,分析制动模式下长编组重载列车在该类地段的行车安全性能,建立列车-线路动力学模型,并基于实测数据进行模型验证。结果表明:当车钩力达最大时,列车不一定行驶在曲线地段;对于1+1编组列车,最大车钩力出现在中部机车处;对于2+0编组列车,当列车从距直缓点900 m的位置处开始制动时的最大车钩力达最大,最大车钩力出现在第62位车钩处;曲线半径应不小于1 200 m,困难条件下不小于1 000 m,缓和曲线长度应不小于150 m。     

E-bikers’ braking behavior: Results from a naturalistic cycling study

Abstract

Objective: The number of e-bike users has increased significantly over the past few years and with it the associated safety concerns. Because e-bikes are faster than conventional bicycles and more prone to be in conflict with road users, e-bikers may need to perform avoidance maneuvers more frequently. Braking is the most common avoidance maneuver but is also a complex and critical task in emergency situations, because cyclists must reduce speed quickly without losing balance. The aim of this study is to understand the braking strategies of e-bikers in real-world traffic environments and to assess their road safety implications. This article investigates (1) how cyclists on e-bikes use front and rear brakes during routine cycling and (2) whether this behavior changes during unexpected conflicts with other road users.

Methods: Naturalistic data were collected from 6 regular bicycle riders who each rode e-bikes during a period of 2 weeks, for a total of 32.5?h of data. Braking events were identified and characterized through a combined analysis of brake pressure at each wheel, velocity, and longitudinal acceleration. Furthermore, the braking patterns obtained during unexpected events were compared with braking patterns during routine cycling.

Results: In the majority of braking events during routine cycling, cyclists used only one brake at a time, favoring one of the 2 brakes according to a personal pre-established pattern. However, the favored brake varied among cyclists: 66% favored the rear brake and 16% the front brake. Only 16% of the cyclists showed no clear preference, variously using rear brake, front brake, or combined braking (both brakes at the same time), suggesting that the selection of which brake to use depended on the characteristics of the specific scenario experienced by the cyclist rather than on a personal preference. In unexpected conflicts, generally requiring a larger deceleration, combined braking became more prevalent for most of the cyclists; still, when combined braking was not applied, cyclists continued to use the favored brake of routine cycling. Kinematic analysis revealed that, when larger decelerations were required, cyclists more frequently used combined braking instead of single braking.

Conclusions: The results provide new insights into the behavior of cyclists on e-bikes and may provide support in the development of safety measures including guidelines and best practices for optimal brake use. The results may also inform the design of braking systems intended to reduce the complexity of the braking operation.     

Domino effect in process-industry accidents - An inventory of past events and identification of some patterns

The paper presents an inventory, perhaps the most comprehensive till date, of the major process-industry accidents involving ‘domino effect’. The inventory includes, among other relevant information, the sequence of accidents that had occurred in each domino episode. The information has been analyzed to identify several patterns which may be useful in further work on understanding domino effect and reducing the probability of its occurrence in future. A concept of ‘local domino effect’ has been introduced.