Job changes, hours changes and the path of labour supply adjustment

This paper uses the first twelve waves of the British Household Panel Survey covering the period 1991-2002 to investigate single women's labour supply changes in response to three tax and benefit policy reforms that occurred in the 1990s. We find evidence of small labour supply effects for two of such reforms. A third reform in 1999 instead led to a significant increase in single mothers' hours of work. This increase was primarily driven by women who changed job, suggesting that labour supply adjustments within a job are harder than across jobs. The presence of hours inflexibility within jobs and labour supply adjustments through job mobility are strongly confirmed when we look at hours changes by stated labour supply preferences. Finally, we find little overall effect on wages.Job mobility; Hours flexibility; Labour supply preferences; Hours-wage trade-off; Monopsony

Job changes, hours changes and labour market flexibility: panel data evidence for Britain

This study uses the first twelve waves of the British Household Panel Survey covering the period 1991-2002 to investigate the extent of constraints on desired hours of work within jobs and the degree of flexibility of the labour market for a sample of women. Our main findings are as follows. First, the largest movements in hours worked are observed for workers who change their jobs. Second, about 40 percent of the women in the sample are not putting in the hours they would like. Most of them (mainly full-timers) would like to work fewer hours at the prevailing hourly wage. Again, women who change job experience the greatest hours changes, especially if they are over- or under-employed. Third, there is evidence of hours constraints. The hours movements among quitters are up to 5 hours greater than the movements among stayers. Fourth, we do not detect systematic time trends in the relationship between hours changes and job changes. But there is some evidence that overemployed women find it increasingly more difficult to move towards their desired hours even after changing job. Fifth, the evidence on a flexible labour market is mixed. We find only partial support for the hypothesis that overemployed or underemployed quitters receive compensating wage differentials if the new job does not satisfy their hours preferences, as well as for the hypothesis that quitters get a wage premium when they end up moving to jobs that constraint their desired hours.Job mobility; Hours constraints; Labour supply preferences; Hours-wage trade-off; Part-time employment.

A new efficient free-rolling tyre-testing procedure for the parameterisation of vehicle dynamics tyre models

This paper describes an efficient tyre test procedure that can be used to collect the data required to parameterise empirical tyre models used in the computer simulations of vehicle dynamics. The new GS2MF FreeRolling test procedure develops established methodologies, such as the time measurement procedure from the TIME project and the MICH2MF measurement protocol developed as alternatives to traditional square matrix testing. The new process is designed to reduce the number of expensive tyre tests without compromising the accuracy of the generated tyre model parameters. The process is demonstrated by a programme of tyre testing carried out using the Calspan TIRF tyre testing facility in the USA, and it is shown here how the GS2MF Flat-Trac® tyre test procedure can be used more efficiently to parameterise the pure lateral and self-aligning moment components for the well-known ‘magic formula’ tyre model. This is achieved using a ‘cruise’-type procedure which is more representative of conditions existing when driving a real vehicle. During the tests, a novel automated logic approach is also proposed to manage the temperature of the tyres. Finally, graph sweeps are introduced at the start and the end of the tests, allowing a judgement to be made as to the influence of the tyre wear on the data obtained throughout the tests. The development of accurate and representative tyre models remains a significant challenge as vehicle manufacturers target increased use of virtual prototypes and simulations. This work contributes to this challenge by improving the efficiency of the expensive testing process needed to parameterise the models. </jats:p

Vehicle agile maneuvering:From rally drivers to a finite state machine approach

Rally drivers can perform extreme maneuvers and keep a vehicle on track by maximizing the vehicle agility. It is remarkable that this is achieved robustly, without a vehicle or tire model in mind. In this study, the Moment Method Diagram and Beta Method representations are used to show the maximum achievable yaw moment generated by the front and rear tires. A new maneuverability map is proposed to bypass the limitations imposed by the steady-state assumptions, based on the wheel slip - yaw moment representation. Furthermore, a simple driving automation strategy is developed to determine the sequence of inputs required for maximizing vehicle agility and negotiating extreme maneuvers. A finite state machine is designed and implemented using a two track vehicle model. The numerical results show that the finite state machine can resemble a rally driver

Highly Skilled Autonomous Vehicles

Recent research suggests that collision mitigation on low grip surfaces might require autonomous vehicles to execute maneuvers such as drift, trail braking or Scandinavian flick. In order to achieve this it is necessary to perceive the vehicle states and their interaction with the environment, and use this information to determine the chassis limits. A first look at the virtual automotive sensing problem is provided, followed by a description of Rally driving modeling approaches. Finally, a co-pilot collision mitigation system for loose surfaces based on a Rally driver Model is proposed