用仪器化的冲击试验系统评定材料的动态性能

由于仪器化的Ｃｈａｒｐｙ冲击试验方法简单经济，已被广泛地用于评价材料的冲击韧性。本文以引进的ＷＯＬＰＥＲＴ冲击试验系统为背景，详细地介绍了计算机辅助的仪器化冲击试验系统（ＣＡＩ）的原理和面貌，对动态断裂韧性Ｋ_（Ｉｄ）的测试原理和方法亦作了较为细致的描述。最后，指出了ＣＡＩ系统几个方面的用途。     

On-road behaviour of younger and older novices during the first six months of driving

Newly qualified drivers are known to have greater crash involvement than more experienced drivers, but does the on-road driving behaviour of young novices differ from that of older novices who might be expected to be more mature and to have different driving needs? Both younger and older novices were compared with experienced drivers in their behaviour driving an instrumented car on three occasions. The three drives were conducted within the novices’ first few months of becoming qualified. All drivers, including both groups of novices, increased their average road speed over the three drives, and all increased their tendency to cut across the central lane marker on bends. The older novices showed some indications of becoming more cautious with experience, by doubling their headway after six months, and by increasing the number of times they glanced into their mirrors at critical points. This increased caution may be attributable to the driving experiences of the older novices, who had experienced twice the crash rate of the younger novices during their first six months of driving.     

Can cars and trucks coexist peacefully on highways? Analyzing the effectiveness of road safety policies in Europe

We examine the impact on the traffic accident rate of the interaction between trucks and cars on Europe’s roads using a panel data set that covers the period 1999–2010. We find that rising motorization rates for trucks lead to higher traffic fatalities, while rising motorization rates for cars do not. Empirically, the model we build predicts the positive impact of stricter speed limit legislation for trucks in the reduction of road fatalities. These findings lend support to European strategies and aimed at promoting alternative modes of freight transport, including rail and maritime transport.     

Speed enforcement in Norway: Testing a game-theoretic model of the interaction between drivers and the police

This paper probes the relationship between changes in the risk of apprehension for speeding in Norway and changes in the amount of speeding. The paper is based on a game-theoretic model of how the rate of violations and the amount of enforcement is determined by the interaction between drivers and the police. This model makes predictions both about how drivers will adapt to changes in the amount of enforcement (the more enforcement, the less violations) as well as how the police will adapt to changes in the rate of violations (the less violations, the less enforcement). The paper attempts to test the game-theoretic model empirically. Testing the model rigorously is difficult, mainly because some of the relevant variables are not reliably measured and are endogenous. Two models were developed: one to identify sources of changes in the rate of violations, one to identify sources of changes in the amount of enforcement. The predictions of the game-theoretic model were supported, although the results were not statistically significant in the model of how the police adapt enforcement to changes in the rate of violations.     

温度对电容薄膜真空计测量影响的实验研究

采用了一支满量程为1333Pa的绝压式电容薄膜真空计,在金属膨胀式真空标准装置上对其进行温度变化的影响实验研究,包括在开和未开控制单元的规管恒温和温度补偿功能两种情况下环境温度变化的实验,并在实验过程中记录了电容薄膜真空计的零点漂移情况。其中,在打开控制单元的规管恒温和温度补偿功能的条件下,电容薄膜真空计测量准确度非常好。而在未打开控制单元的规管恒温和温度补偿功能的条件下,在10^-2～10^-1Pa两个量级上电容薄膜真空计的示值与标准值有较大偏差,最大偏差为36％;而在1～10^2Pa量级上电容薄膜真空计测量准确度也非常好。     

An illusory size–speed bias and railway crossing collisions

Collisions between motor vehicles and trains at railway level crossings have been a high-profile issue for many years in New Zealand and other countries. Errors made in judging a train's speed could possibly be attributed to motorists being unknowingly subjected to a size–speed illusion and this could put them at considerable risk. Leibowitz (1985) maintained that a large object seems to be moving slower than a small object travelling at the same speed. Support has been provided for Leibowitz's theory from studies using simple shapes on a screen. However, the reasons behind the size–speed illusion remain unknown and there is no experimental evidence that it applies to an approaching train situation. To investigate these issues, we tested observers’ relative speed estimation performance for a train and a car approaching at a range of speeds and distances, in a simulated environment. The data show that participants significantly underestimated the speed of the train, compared to the car. A size–speed illusion seems to be operating in the case of the approaching train in our simulation and may therefore be a risk factor in some railway level crossing collisions.     

Investigating the influence of curbs on single-vehicle crash injury severity utilizing zero-inflated ordered probit models

The severity of traffic-related injuries has been studied by many researchers in recent decades. However, previous research has seldom accounted for the effects of curbed outside shoulders on traffic-related injury severity. This study applies the zero-inflated ordered probit (ZIOP) model to evaluate the influences of curbed outside shoulders, speed limit change, as well as other traditional factors on the injury severity of single-vehicle crashes. Crash data from 2003 to 2007 in the Illinois Highway Safety Database were employed in this study.     

Impairment of a speed management strategy in young drivers under high cognitive workload

Background

A training method known as Episodic training has shown promise in reducing speeding behavior in young drivers (Prabhakharan and Molesworth, 2011). The present study aimed to investigate how cognitive resources are utilized to implement this behavioral change.

Method

60 participants were randomly divided into four groups and completed a simulated training drive in Week 1 followed by a 10 km simulated test drive in Week 2. As part of the test drive, two groups were asked to complete a secondary task (mental arithmetic task) in addition to the test drive.

Results

The results indicated that implementing a speed management strategy elicited by Episodic training was successful in isolation, but came at a cognitive trade-off when performed in conjunction with a secondary task.

Conclusion

From an applied perspective, these results suggest driver training programmes should compartmentalize driver training in order to reduce the cognitive load experienced by trainee drivers, and hence facilitate in driver skill acquisition.     

Vehicle speed affects both pre-skid braking kinematics and average tire/roadway friction

Vehicles decelerate between brake application and skid onset. To better estimate a vehicle's speed and position at brake application, we investigated how vehicle deceleration varied with initial speed during both the pre-skid and skidding intervals on dry asphalt. Skid-to-stop tests were performed from four initial speeds (20, 40, 60, and 80 km/h) using three different grades of tire (economy, touring, and performance) on a single vehicle and a single road surface. Average skidding friction was found to vary with initial speed and tire type. The post-brake/pre-skid speed loss, elapsed time, distance travelled, and effective friction were found to vary with initial speed. Based on these data, a method using skid mark length to predict vehicle speed and position at brake application rather than skid onset was shown to improve estimates of initial vehicle speed by up to 10 km/h and estimates of vehicle position at brake application by up to 8 m compared to conventional methods that ignore the post-brake/pre-skid interval.     

无工装定位数模测量技术试验设计论证

为了解决在无工装定位的条件下激光跟踪仪能直接测量产品,制订了数模测量技术试验设计论证方案。通过对坐标系建立与转换有序地试验设计实施、测量基准点约束和自由两种状态下的翔实严谨的科学试验论证、测量数据在三维数模(CATIA理论数模)分析、经过四次生产现场产品的测试,获得了科学的实验成果、专利产权的试验设计成就。研究的成果是减少了检验工装或替代了工装,可用于实地测量产品的尺寸、形状、位置、空间等真实状态,得到的三维数据精确可靠且直观,为工程设计解决当前飞机活动面交点不协调难题提供了准确的数据,技术含金量高操作又简便。实验表明无工装定位数模测量技术在航空航天产品制造测控领域中大有应用发展前景。