Race car drivers can offer insights into vehicle control during extreme manoeuvres; however, little data from race teams is publicly available for analysis. The Revs Program at Stanford has built a collection of vehicle dynamics data acquired from vintage race cars during live racing events with the intent of making this database publicly available for future analysis. This paper discusses the data acquisition, post-processing, and storage methods used to generate the database. An analysis of available data quantifies the repeatability of professional race car driver performance by examining the statistical dispersion of their driven paths. Certain map features, such as sections with high path curvature, consistently corresponded to local minima in path dispersion, quantifying the qualitative concept that drivers anchor their racing lines at specific locations around the track. A case study explores how two professional drivers employ distinct driving styles to achieve similar lap times, supporting the idea that driving at the limits allows a family of solutions in terms of paths and speed that can be adapted based on specific spatial, temporal, or other constraints and objectives. 相似文献
The North Bay of Biscay continental shelf is a major French demersal fishery, but little was known on the trophic food web of its benthic communities. In order to determine the benthic trophic web, the objectives of this study are to describe the macro- and megafaunal benthic community structure (species richness, abundance and biomass) and to establish the trophic pathways (food sources and trophic levels) by applying carbon and nitrogen stable isotopic analysis to the main benthic and demersal species (invertebrates and fish). Two distinct benthic communities have been identified: a muddy sand community within the central part of the bay, and an outer Bay of Biscay Ditrupa sand community of higher species richness, abundance and biomass than the muddy sand community. Deposit-feeders, suspension feeders and predators, distributed in three main trophic levels, dominate both communities. Large differences in stable carbon ratio values within the primary consumers provide evidence of two different food sources: i) a pelagic food source made up of recent sedimenting particulate organic matter on which zooplankton and suprabenthos feed and ii) a benthic detrital food source supplying deposit feeders and partly benthic suspension feeders. Differences in isotopic signatures were also observed within the upper trophic levels that allowed estimation of the contribution of each food source component to the diet of the upper consumers. Finally, the use of stable isotopic composition together with the species' feeding strategy allow identification of the main differences between the trophic functioning of the two benthic communities and highlight the importance of the role of detrital pathways in the carbon cycling within the continental shelf benthic trophic web. 相似文献
The transport demand in most major cities around the world can only be met with a high‐quality public transport system. The requirements on bus, rail, underground and tram systems are manifold with reliability and efficiency as the key factors. The service operating hours and the size of the network are often extended in order to serve the needs better. Further, most metropolitan areas are trying to provide more incentives for citizens to leave the car at home and use the local transit systems instead. The reasons are well known. Not only does a public transport system only make economical sense if it is well used, but most urban areas with a high car‐dependency face at least three major problems; safety, congestion, and pollution (noise and air pollution, land separation, etc.). It is generally recognised that to decrease car usage and to increase public transport usage a stick & carrot approach is needed. The London congestion‐charging scheme is an example since all revenues collected by the scheme are put into the improvement of bus and underground services. 相似文献
Advanced Vehicle Control Systems (AVCS), when realized, should substantially increase the convenience and safety of highway travel. Automated lateral control is an important step in the realization of AVCS. Much research has been concerned with lateral control during low-g maneuvers. However, before passengers' lives are in the hands of any automated laterally-controlled vehicle, the vehicle controller must be designed to respond to emergency situations where high-g maneuvers may be necessary.
This paper presents the development of a nonlinear-gain-optimized (NGO) controller for emergency automated lateral control of four wheel steered automobiles. Continuous gain equations (GE) are used to account for changes in the vehicle speed. The NGO controller uses a linear vehicle/tire model to define the state model. The response of a nonlinear vehicle/tire model is used to choose the performance index that optimizes the feedback gains for high-g emergency maneuvers at discrete speeds. Continuous gain equations are then derived as least-square approximations to each set of gains.
The performance of the four-wheel-steer continuous gain equations (4WS-GE) controller is compared to that of a two-wheel-steer continuous gain equations (2WS-GE) controller. Significant improvements in vehicle response are realized by using the 4WS-GE controller. The robustness of the controller's performance is examined with respect to changes in tire parameters and changes in vehicle mass. 相似文献
A 2-D analysis of the soil-structure interaction for a jack-up platform is presented. The special features of the analysis are:
• -soil behaviour modelling under cyclic loading uses elasto-plastic equations with a multiple yield surface and kinematical hardening;
• -the study is not executed on a single isolated spud-can, but on a more comprehensive structural model including the soil and a 2-D reduction of a complete jack-up structure;
• -the loading history consists of some one-hundred cycles representing two storm sea states separated by small set-up cycles.
The main result is that the bottom fixity displayed during the first storm is not significantly degraded during the second storm, even though irrecoverable displacements and rotations occur. 相似文献