Applied Mechanics and Materials Vols. 253-255

Abstract: Numerical simulations were carried out to investigate the air flow and pressure distributions beneath high speed trains, based on the three-dimensional Reynolds-averaged Navier-Stokes equations with the SST k-ω two-equation turbulence model. The simulation scenarios were of the high speed train, the CRH2, running in the open air at four different speeds: 200km/h, 250km/h, 300km/h and 350km/h. The results show that, the highest area of pressure is located at the front underbody part of the train whist the pressure for rest of the train is relatively small. Increasing speed does not visibly increase the pressure coefficient, indicating that the pressure increases with the square of the operational speed.

Abstract: The purpose of this research is to develop a multi-input control algorithm for the speed regulation of railway transit vehicle. The Taipei railway transit vehicle is chosen as the simulation object in this research. This transit vehicle has three carts and is push-pull type; only the first and the last carts are empowered. The control algorithm is to calculate the appropriate driving forces for the power units such that vehicle can follow a specified speed pattern. A feed-forward and feed-back control algorithm is designed to achieve this purpose. In the system, a dynamics variable observer is also developed to reduce required sensors for the controller. The results show that the developed controller is suitable for this purpose and the observer achieves acceptable observation quality for the controller application.

Abstract: In order to study how the parameters of floating slab track and the speed of the train influence the vehicle-track coupling system，the paper built the vehicle-track coupling dynamic system. In the coupling model, the train is simplified a multi-rigid body system. The rail and the floating slab are considered as Euler beam. The wheel-rail relation is regarded as non-linear Hertz contact. The paper solved the dynamic equation of the vehicle-track coupling dynamic system with prediction-correction Newmark-β numerical integration method. Through numerical simulation, the paper gained the affect of fastener stiffness, slab support stiffness, and the speed of train to the characteristic of the coupling system containing the vehicle acceleration, wheel-rail force, the vibration of the track and the counter-force from the basis. The paper provides a reference for the selection of the track parameters and the speed of vehicle.

Abstract: In high speed train, to obtain precise speed is important to high performance control, though the transducers used in the train are usually low resolution. The speed measurement was analyzed both on precision and update rate according to the control requirement. A comprehensive measure and calculation solution for traction motor speed measurement is presented. Measure clock period is adjusted according to motor’s different speed range and can obtain good measurement precision both in low and high speed range. The speed update rate can also be guaranteed. The proposed method is implemented and validated by hardware in loop simulation system.

Abstract: In this paper, using mechanical system dynamic simulation analysis software ADAMS, we create a multi-system dynamical model of an oversize double-articulated urban bus based on multi-body system. And then, we conduct the simulation test of changing lane of this vehicle with different front wheel angle for studying its lane changing characteristics as well as the influence degree to the surrounding vehicles; give a comparison analysis of the simulation result and the sample vehicle road test result, and verify the correctness and reasonability of the created virtual prototype model. The study result shows that the created digitized virtual prototype can effectively analyze the lane changing characteristics of the oversize double-articulated bus.

Abstract: The safe speed in bridge area and the security of the bridge’s structure is a technical and a management issue; it should pay highly attention in terms of design, maintenance, and operation and management. The point of the shipping departments and the bridge designing departments for reference in two distinguished aspects are discussed when it comes into the problems of the speed in bridge area. The conception of “safe speed in bridge area” is based on current impact determination for pier and the study of safe speed at home and abroad. The ship adopted the safe shipping speed in bridge area and can meet the requirements of the safe navigation demanded by the shipping departments, and its velocity value can provide reference for the bridge designing in terms of anti-collision. The practical experiment on super large bridge in Changzhutan intercity railway and the ship model test on navigation show that the presentation of safe speed in bridge area ships was a relatively scientific method, and the presentation can provide new idea on solving contradiction between the construction of the bridge and the navigation part.

Abstract: In order to design a double buoys mooring system in the estuary of Yalu River for loading work of 40,000 tons of bulk cargo ship, the article mainly based on the practicality of the meteorological condition of this sea area and the data of the vessel as well as the national criterion, do some calculations of wind force, current force, wave force as well as the total force on the ship, with the calculation result to make a designation of double mooring buoy system, decide the size of the mooring buoy, the size and length of the chain, the size and the depth of the Deadman. The construction according to the designation has a good effect; the method of calculation and the designation are proved useful.

Abstract: In order to meet the highway safety requirements of the bus under different speeds, the model of highway bus and W-beam were established in UG software and the collision dynamics simulation was analyzed in ADAMS software. During a number of simulation experiments, the impact force and the lateral deformation displacements would be done through the W-beam was collided by the bus in different speeds. The result was proven to meet the regulatory requirements of the evaluation specification for highway safety barriers. The result show that: semi-rigid guardrail can be better deformation and guiding effect when the speed of bus was lower than 80 km/h, but when the speed was higher than 80 km/h, the collision avoidance effect of guardrail was poor and the bus was easy to cross the guardrail to case secondary accident.

Abstract: In this paper, a mathematical model for ship rudder and fin integrated control system is present. The closed gain shaping algorithm (CGSA) strategy is applied to design an integrated rudder and fin stabilizer to overcome the arbitrary selection of weighting function in H_∞ mixed sensitivity robust controller design procedures. The CGSA methods give a relatively more concise and reliable design method for the ship rudder and fin integrated control system. The simulation results show that the ship CGSA rudder/fin integrated controller can satisfactorily achieve roll motion reduction and yaw stabilization simultaneously as well as guarantee the levels of robust stability and control performance in the different sea conditions.

Abstract: The new linear induction motor (LIM) driven urban rail transit system is favored for more rapidly and reliability, cost-effective and environmental friendly. As the core of the LIM vehicle, network system is proposed in this paper. The scheme of network system is given by using Beckhoff programmable logical controller and its sub-modules, and CANopen protocol is applied in network communication. The performance of the network system is demonstrated by the experiment results. The research and design can be a useful guidance to engineering application for future LIM urban rail transit construction in China.