Abstract

Reducing CO2 emission is one of the major environmental challenges for transportation. One way to solve this problem is to replace old cars that use fossil fuels (petrol, diesel) with new electric cars. In this paper, the existing model for calculating well-to-wheels CO2 emission during the life cycle of the car (fossil fuel car and electric car) is upgraded. The developed model is used for comparing optimal lifetime and optimal car’s kilometers driven during a lifetime in the replacement process of a fossil fuel car with a new electric car. We find that reducing CO2 emission depends on the type of fossil fuel, and the weight of fossil fuel cars and electric cars. Changing petrol fossil fuel cars with lower weight electric cars have the greatest potential for reducing CO2 emission. However, the introduction of electric cars does not achieve a significant reduction of CO2 emission in countries where electricity is primarily produced in thermal power plants, i. e. in countries with a high emission factor of electricity production. [Projects of the Serbian Ministry of Education, Science and Technological Development, Grant no. TR 36010, Grant no. TR 36022 and Grant no. TR 36027] Document type: Article

Abstract

This paper investigates the trajectory generation problem for an advanced driver assistance system that could sense the driving state of the vehicle, so that a collision free trajectory can be generated safely. Specifically, the problem of trajectory generation is solved for the safety assessment of the driving state and to manipulate the vehicle in order to avoid any possible collisions. The vehicle senses the environment so as to obtain information about other vehicles and static obstacles ahead. Vehicles may share the perception of the environment via an inter-vehicle communication system. The planning algorithm is based on a visibility graph. A lateral repulsive potential is applied to adaptively maintain a trade-off between the trajectory length and vehicle clearance, which is the greatest problem associated with visibility graphs. As opposed to adaptive roadmap approaches, the algorithm exploits the structured nature of the environment for construction of the roadmap. Furthermore, the mostly organized nature of traffic systems is exploited to obtain orientation invariance, which is another limitation of both visibility graphs and adaptive roadmaps. Simulation results show that the algorithm can successfully solve the problem for a variety of commonly found scenarios. Document type: Article

Abstract

The 20th century witnessed revolutionary developments in transportation technology with major impacts on the form and character of cities. Progress in increasing mobility has brought many benefits as well as serious problems, particularly in deterioration of livability and sustainability. Increase in auto ownership led to serious problems of chronic traffic congestion. Attempts to rebuild cities to provide full accommodation of private cars have led to serious problems of auto dependency and deterioration of cities. Experiences from recent decades have shown that urban transportation is much more complex than usually realized. Livable and sustainable cities require policies that lead to creation of a transportation system consisting of coordinated public transit and private cars, and encourages pedestrian environment and efficient, sustainable development. Great need for better understanding of the complex problems in implementing incentives and disincentives aimed at achieving intermodal balance is emphasized. Brief descriptions of cities which lead in achieving such livable conditions is followed by a summary of lessons and guidelines for the future. Document type: Article

Abstract

In modern electric equipment, especially electric vehicles, inverter control systems can lead to complex shaft voltages and bearing currents. Within an electric motor, many parts have electrical failure problems, and among which bearings are the most sensitive and vulnerable components. In recent years, electrical failures in bearing have been frequently reported in electric vehicles, and the electrical failure of bearings has become a key issue that restricts the lifetime of all-electric motor-based power systems in a broader sense. The purpose of this review is to provide a comprehensive overview of the bearing premature failure in the mechanical systems exposed in an electrical environment represented by electric vehicles. The electrical environments in which bearing works including the different components and the origins of the shaft voltages and bearing currents, as well as the typical modes of electrical bearing failure including various topographical damages and lubrication failures, have been discussed. The fundamental influence mechanisms of voltage/current on the friction/lubrication properties have been summarized and analyzed, and corresponding countermeasures have been proposed. Finally, a brief introduction to the key technical flaws in the current researches will be made and the future outlook of frontier directions will be discussed. Document type: Article

Abstract

In order to solve problems arising in ordinary heat pump system for pure electric vehicles at ultra-low temperature, a low pressure gas-injection scroll compressor is designed, and a mathematical model is established. Comparison with the experimental results shows good accuracy of the theoretical prediction. Document type: Article

Abstract

Piping inspection robots are of greater importance for industries such as nuclear, chemical and sewage. Mechanisms having closed loop or tree-like structures can be employed in such pipelines owing to their adaptable structures. A bio-inspired caterpillar type piping inspection robot was developed at Laboratoire des Sciences du Numé rique de Nantes (LS2N), France. Using DC motors and leg mechanisms, the robot accomplishes the locomotion of a caterpillar in six-steps. With the help of Coulomb&rsquo s law of dry friction, a static force model was written and the contact forces between legs of robot and pipeline walls were determined. The actuator forces of the DC motors were then estimated under static phases for horizontal and vertical orientations of the pipeline. Experiments were then conducted on the prototype where the peak results of static force analysis for a given pipe diameter were set as threshold limits to attain static phases inside a test pipeline. The real-time actuator forces were estimated in experiments for similar orientations of the pipeline of static force models and they were found to be higher when compared to the numerical model. Document type: Article