Charging Electric Vehicles Using Regenerated Energy from Urban Railways
Nowadays transport system is one of the most important producers of air pollution in cities. Urban railways and electric vehicle will play a fundamental role to accomplish the sustainability of cities. Urban railways are right now an efficient mode of transport. However it is necessary to continue improving its energy efficiency in view of the demand growth. On the other hand, electric vehicles need a charging infrastructure to support their market penetration. In this context, the use of the railway electrical infrastructure to charge electric vehicles could bring several benefits. First of all, there is a cost reduction effect because of the use of an existing installation. Besides, part of the regenerated energy that cannot be accepted by other trains can be used to charge electric vehicles, improving the efficiency of the global system. In this paper, a new system for the global energy management between the railway infrastructure and the electric vehicles is proposed. Besides, the global energy savings that can be obtained using railway electrical infrastructure to charge electric vehicles has been assessed.
Increasing the Regenerative Braking Energy for Railway Vehicles
Regenerative braking improves the energy efficiency of railway transportation by converting kinetic energy into electric energy. This paper proposes a method to apply the Bellman-Ford (BF) algorithm to search for the train braking speed trajectory to increase the total regenerative braking energy (RBE) in a blended braking mode with both electric and mechanical braking forces available. The BF algorithm is applied in a discretized train-state model. A typical suburban train has been modeled and studied under real engineering scenarios involving changing gradients, journey time, and speed limits. It is found that the searched braking speed trajectory is able to achieve a significant increase in the RBE, in comparison with the constant-braking-rate (CBR) method with only a minor difference in the total braking time. An RBE increment rate of 17.23% has been achieved. Verification of the proposed method using BF has been performed in a simplified scenario with zero gradient and without considering the constraints of braking time and speed limits. Linear programming (LP) is applied to search for a train trajectory with the maximum RBE and achieves solutions that can be used to verify the proposed method using BF. It is found that it is possible to achieve a near-optimal solution using BF and the solution can be further improved with a more complex search space. The proposed method takes advantage of robustness and simplicity of modeling in a complex engineering scenario, in which a number of nonlinear constraints are involved.
On the Role of Professional Sports in the National Economy Under the Market Economy Conditions
Through the research of the present situations of the professional sports at home and abroad and its influence on economy, this paper points out the opportunities, challenges and the exist- ing main problems that the professional sports faces in the transitional peried-from plan economy to market economy, then elucidates that the professional sports can becompletely developed and improved and play an important role in the national economy under the market economy conditions.