Advanced Materials Research Vols. 779-780

Abstract: The paper has carried out continued tests on a curve of a heavy haul railway in China for its rail profiles. Based on the data, the paper has counted the development of the rail profile wear, and then analyses the influence of wheel-rail contact geometry on the rail profile wear. The results show that the wear of high rails develops around the rail corners, while the one of low rails around the rail top. The development of the rail wear speeds up after the transport mass passes 210MGT. The wheel-rail contact geometry deteriorates when the transport mass grows up to 60MGT and lower than 210MGT.

Abstract: The paper tests the rail profiles of Shanghai-Nanjing PDL after its rail pre-grinding. The grinding values are counted, which shows that the grinding mainly occurs on the inner side of rail top, ranging from 0 to 1.26mm. Wheel-Rail Contact Geometry is also analyzed. Results shows that after pre-grinding, the wheel-rail contact points concentrate to the center of rail top, and it is good for rail wear control. But the rolling radius difference decreases and it weakens the rails ability of return the wheels position.

Abstract: As an important rolling connection of the wind turbine, yaw slewing bearing plays a critical role in the structure reliability. Therefore, effective health monitoring of a slewing bearing to execute timely maintenance or replacement have attracted significant interest. In order to monitor working conditions on line, various sensors have been used. This paper discussed the installation approaches of various sensors in a yaw slewing bearing, and analyzed the effect of local structure change on the fatigue life of a 1.5MW slewing bearing by MSC.FATIGUE, and thus providing an effective reference for structural design of a smart slewing bearing.

Abstract: Taking the bending stiffness, cable static sag and cable inclined angle into consideration, equations of space free vibration of the cable-damper system are derived in this paper. Joining the variable separation strategy and center difference method, the partial differential equations are discretized in space and a set of complex eigenvalue equations, which are solved by state space method, are derived, and both the maximum modal damping ration and the optimal damper parameter are obtained. Several typical stay cables are investigated for both the in-plane and out-of-plane modes under different cable parameters and damper parameters. The results demonstrate that modal damping ratio for the first in-plane mode is significantly affected by the cable static sag only, but those for the other modes affected by cable sag are slight, and cable static sag do not affect the optimal damper parameter for all modes, however the bending stiffness will changes both the maximum modal damping ratios and the optimal damper parameters. Some valuable suggestions are proposed for the optimal damper design.

Abstract: The rolling motion analysis of ships or other marine structures is of paramount importance. However, one of the thorniest issues in the analysis is the determination of roll damping. The main objective of this work is to apply the Partial Least-Squares regression into the Bass Energy Method and Roberts Method, which are used for the identification of non-linear roll damping parameters. When the number of sample points decreases due to limitations of the experimental conditions and other factors, the differences between the results obtained from Partial Least-Squares Regression and from traditional Least-Squares method demonstrate the applicability of the proposed method.

Abstract: Space of surrounding rock pressure is caused by underground excavation surrounding rock mass and the supporting force of deformation or destruction. Weight model, reduction weight model, tunnel specification and finite element model are four commonly surrounding rock pressure calculation methods. This paper put forward a more reasonable tunnel surrounding rock pressure calculation model by using the finite element analysis software, numerical simulation of tunnel excavation and comparison and analysis of the four calculations results.

Abstract: It is obvious that luminance reduction coefficient standards do not satisfy a driver’s comfort and safety in an expressway tunnel threshold zone. In fact, the standards may impair a driver's vision and increase the probability of accidents. Smaller luminance reduction coefficients are economical but unsafe. The threshold zone lighting of existing and newly designed tunnels needs to be analyzed to prevent safety luminance problems. This paper provides a method, CRP, to evaluate drivers’ safety and comfort caused by tunnel luminance reduction coefficients, based on analyzing drivers' visual demands. It consists of field experiments to examine CRP and luminance reduction coefficient under different operating speeds in expressway tunnel threshold zones. A regression model is developed according to the comfort and safety threshold; this was based on changing the driver's rate of pupil adjustment by 20%, by which we can obtain the comfort and safety luminance reduction coefficient. The expressway tunnel threshold zone luminance reduction coefficient standard of 0.031 was determined at a speed of 60km/h. This is higher than the Chinese standard.

Abstract: In order that the vehicle-track dynamic simulation can reflect the actual operation better, the running simulation theory was introduced into the analysis process of the high-speed railway dynamic response. Firstly, the data (including time, mileage, velocity, acceleration, etc.) of train running simulation was worked out by traction calculation. Secondly, according to the structure feature of high-speed railways vehicle and track, the vehicle-track coupled dynamic model was built. Non-linear Hertz theory was used for modeling the wheel-rail contact. Then the wheel-track creep force was obtained by using Kalker's creep theory and Shen's non-linear theory. Meanwhile, various track spectrums were simulated. Furthermore, the running simulation data as the original data were used to work out the real-time dynamic response indices in the dynamic calculation process. Thirdly, the indices would be applied to the alignment comfort evaluation. Finally, the system was developed out and the rationality and practicability of the method were verified through an example.

Abstract: In order to automatically generate the optimal highway alignment and avoid omitting valuable scenarios, a bidirectional dynamic programming approach for alignment optimization was put forward. Firstly we established a three-dimensional search grid in the study area. Then dynamic programming was used to find the best alignments within the vast study area. A double-direction searching strategy was proposed to obtain a group of scenarios ranking by their corresponding comprehensive cost. The alignments were then refined with Powell method so that the resulting alignments could deviate from the grid points to reach better solutions. Examples demonstrated that this approach can obtain global optimal alignment with good diversity.

Abstract: After the fuel changed fromgasoline to kerosene of internal combustion engine, the engine cold startperformance is poor due to the poor spray evaporation of kerosene fuel. In thepaper, the ignition factors are to be analyzed based on the gas dischargetheory. Improving the spark plug discharge and increasing the ignition energyare used to improve the cold start performance of engine. The experimentalresults show that the method can improve the cold start performance of engine,which provides the basis for the engine burning kerosene fuel