Research on the management innovation and practice of construction for Beijing-Shanghai high speed railwayEI北大核心

Construction of Beijing-Shanghai high speed railway is unprecedented great feat. Around the construction goal of "world class", a series innovation and practice measures are taken in the construction ideas, organization and management, technology research, investment financing, quality, safety, investment, construction period, environmental protection, stability, and so on, to lay a solid foundation of completing Beijing-Shanghai high speed railway construction efficiently. In the current new situation of speeding up railway construction, systematically summarizing the results of management innovation and practice for Beijing-Shanghai high speed railway has very important practical significance to improve the level of railway construction project management in our country.     

Comparison of PMP and DP in fuel cell hybrid vehicles

Pontryagin’s Minimum Principle (PMP) and Dynamic Programming (DP) are both from the optimal control theory and can both achieve optimal trajectories when they are applied to power management strategies of hybrid vehicles. However they have totally different control concepts. In order to select the superior one, the PMP-based and the DP-based power management strategies are introduced and compared for a fuel cell hybrid vehicle (FCHV) in this paper. The two power management strategies are applied to the FCHV in a computer simulation environment, and the simulation results from the two strategies are compared when the control variable for the PMP is fuel cell system (FCS) net power and for the DP is battery power. As a result, the superiority of the PMP-based power management strategy is proved.     

Precise and reliable positioning based on the integration of navigation satellite system and vision system

In this paper, we propose a precise and reliable positioning method for solving common problems, such as a navigation satellite’s signal occlusion in an urban canyon and the positioning error due to a limited number of visible navigation satellites. This is an integrated system of the navigation satellites system and a vision system. In general, the navigation satellite positioning system has a fatal weakness in that it can not calculate a position coordinate when its signal is occluded by some obstacle. For this reason, positioning by using the navigation satellites system can not be used for a variety of applications. Therefore, we propose as a method to integrate both the navigation satellites system and the vision system. Some target objects that have accurate position coordinates, for example, in an outdoor shaded area like an urban canyon, are installed into the vision system. When the vision system recognizes a target object it loads the accurate coordinate of that target object. Then, it measures the distance by using the disparity from the camera sensor to the target object. These distance and object coordinate data are used for positioning with the navigation satellites system’s data. This integrated system can be used for the positioning solution where the user is in unfavorable conditions. This paper shows that the algorithm of integrated system and the numerical test performed. The results indicate that the reliable and stable positioning can be obtained by introducing the vision system to the satellite navigation system.     

Characteristics on NOx adsorption and intermediates of LNT catalyst

Several NOx reduction technologies under development in recent years have now been commercialized, including selective catalytic reduction (SCR) with NH₃ or hydrocarbons, and Lean NOx Trap. The aim of the present study is to investigate characteristics on NOx adsorption according to the oxygen concentration, de-NOx performance according to lean/rich injection cycle and toxic intermediates at LNT downstram for lean-burn gasoline engine. Under oxygen of 6%, NOx storage capacity was the highest, showed the highest NOx conversion of 98%. The reason for this phenomena is because the excited oxygen atoms at high oxygen concentration increased oxidizing power of NO. Under low temperature of 205°C, LNT catalyst showed the least NOx conversion of 14% because its activity became lower, while the generation rate of toxic HNCO was highest as CO which is generated during the rich condition, reacts with NOx stored on Ba site.     

Computational model for analyzing the kinematics and compliance characteristics of a commercial vehicle’s front suspension system

This paper develops a computational model that can analyze the kinematics and compliance characteristics of the front suspension of a commercial vehicle. This computational model is called the flexible multi-body dynamic model because it is developed by interfacing the finite element model of the multi-leaf spring with the dynamic model of the front suspension. In this paper, the bump mode and roll mode tests are performed with a suspension parameter measuring device (SPMD). An excitation load for creating the bump mode and roll mode motion is applied on the left and right tires slowly in in-phase and out-of-phase modes. In the test, wheel rate, toe angle change, caster angle change, and camber angle change, which together represent the wheel alignment, are measured along with the longitudinal and lateral wheel center loci which together represent the wheel center trajectory change. The reliability of the developed computational model is verified by comparing the simulation results with the SPMD test results. The developed flexible multi-body computational model will provide useful information on kinematics and compliance characteristics in the earliest stages of the commercial vehicle design process.     

Modeling and control of an anti-lock brake and steering system for cooperative control on split-mu surfaces

The brake and steering systems in vehicles are the most effective actuators that directly affect the vehicle dynamics. In general, the brake system affects the longitudinal dynamics and the steering system affects the lateral dynamics; however, their effects are coupled when the vehicle is braking on a non-homogenous surface, such as a split-mu road. The yaw moment compensation of the steering control on a split-mu road is one of the basic functions of integrated or coordinated chassis control systems and has been demonstrated by several chassis suppliers. However, the disturbance yaw moment is generally compensated for using the yaw rate feedback or using wheel brake pressure measurement. Access to the wheel brake pressure through physical sensors is not cost effective; therefore, we modeled the hydraulic brake system to avoid using physical sensors and to estimate the brake pressure. The steering angle controller was designed to mitigate the non-symmetric braking force effect and to stabilize the yaw rate dynamics of the vehicle. An H-infinity design synthesis was used to take the system model and the estimation errors into account, and the designed controller was evaluated using vehicle tests.     

Lateral controller design for an unmanned vehicle via Kalman filtering

This paper proposes a lateral control system for an unmanned vehicle that is designed to improve the responsiveness of the system with the use of a PD control. The vehicle heading error can be stabilized, and the transient response characteristics can be improved using the proposed controller. A mathematical model of the vehicle dynamics using two degrees of freedom was developed for the controller design. The waypoint tracking method for autonomous navigation was tested with incorporation of the Point-to-Point algorithm with position and heading measurements received from GPS receivers via Kalman filtering. The performance of the designed controller was verified through experiments with a real vehicle.     

Design optimization of an injection mold for minimizing temperature deviation

The quality of an injection molded part is largely affected by the mold cooling. Consequently, this makes it necessary to optimize the mold cooling circuit when designing the part but prior to designing the mold. Various approaches of optimizing the mold cooling circuit have been proposed previously. In this work, optimization of the mold cooling circuit was automated by a commercial process integration and design optimization tool called Process Integration, Automation and Optimization (PIAnO), which is often used for large automotive parts such as bumpers and instrument panels. The cooling channels and baffle tubes were located on the offset profile equidistant from the part surface. The locations of the cooling channels and the baffle tubes were automatically generated and input into the mold cooling computer-aided engineering program, Autodesk Moldflow Insight 2010. The objective function was the deviation of the mold surface temperature from a given design temperature. Design variables in the optimization were the depths, distances and diameters of the cooling channels and the baffle tubes. For a more practical analysis, the pressure drop and temperature drop were considered the limited values. Optimization was performed using the progressive quadratic response surface method. The optimization resulted in a more uniform temperature distribution when compared to the initial design, and utilizing the proposed optimization method, a satisfactory solution could be made at a lower cost.     

Research on the Brayton cycle design conditions for reliquefaction cooling of LNG boil off

This paper analyses the Brayton cooling cycle for the reliquefaction of the boil off on liquefied natural gas (LNG) vessels. By performing a thermodynamic study, we analysed and evaluated the conditions, parameters and energy consumption required in the process, including the influence of the choice and variation of diverse factors on the operating conditions and power.     

Control of drivers' route choice: Pipe dream or panacea?

In most large cities traffic flow is controlled or manipulated in a number of ways. The methods used are mostly negative in the sense that they restrict the driver's choice of alternative routes rather than encourage him to use a particular one. This paper reviews some of the conventional measures and goes on to consider whether a more positive approach to route control might be justified, by inducing a more efficient or acceptable pattern of traffic movement in urban areas. The principal criteria for an efficient pattern are taken to be the total rate of expenditure of vehicle mileage and the frequency of route crossings, and an attempt is made to evaluate the potential benefits of route control in these terms. Social, technical and political considerations suggest that compulsory control will not be feasible for some time (at least, in the UK), but if the benefits to drivers as individuals can be shown to be worthwhile an advisory system might be practicable. Some possible systems are briefly outlined.The author is grateful to the City Engineer of Westminster City Council, Mr A.J. Cryer, for permission to publish this paper,which, however, does not necessarily represent the views . City Council. The author is greatly indebted to E. M. Holroyd for numerous suggestions and advice.