Robust optimisation of railway crossing geometry

This paper presents a methodology for improving the crossing (frog) geometry through the robust optimisation approach, wherein the variability of the design parameters within a prescribed tolerance is included in the optimisation problem. Here, the crossing geometry is defined by parameterising the B-spline represented cross-sectional shape and the longitudinal height profile of the nose rail. The dynamic performance of the crossing is evaluated considering the variation of wheel profiles and track alignment. A multipoint approximation method (MAM) is applied in solving the optimisation problem of minimising the contact pressure during the wheel–rail contact and constraining the location of wheel transition at the crossing. To clarify the difference between the robust optimisation and the normal deterministic optimisation approaches, the optimisation problems are solved in both approaches. The results show that the deterministic optimum fails under slight change of the design variables; the robust optimum, however, has improved and robust performance.     

瓦锡兰的服务工具箱中有什么

对这个问题的简单回答就是:服务可以保持瓦锡兰产品的高效工作能力-针对65,000 MW的2冲程发动机和70,000 MW的4冲程发动机-在每一年的每一天、每一小时都能够满足其所有者的需要。这就意味着我们必须能够随时随地提供必要的零件、人工和服务,用以保持产品最高的性能质量。     

ZF 8档混合动力自动变速器新模块系统

在混合动力8档自动变速器内取消液力变矩器,将离合器、电机、扭振减振器、双质量飞轮、液压机构都有效紧凑地安装在变速器内。     

Estimating the inefficiency in the Norwegian bus industry from stochastic cost frontier models

A stochastic cost frontier function based on data from 170 of the 175 Norwegian subsidized bus companies is estimated under two alternative presumptions regarding the distribution of the inefficency among the bus operators. When the inefficiency is assumed to be half-normally distributed, the average inefficiency in the industry is estimated to be 13.7 per cent. This calculated value is nearly halved (7.2 per cent) when the exponential distribution is applied, while the ranking of the companies according to inefficiency is unchanged. By regressing the estimated inefficiency values for each company on some exogenous variables describing its ownership structure and the subsidy policy which it faces, it is seen that inefficiency of the companies which negotiate with the public authorities over the subsidy amounts is slightly higher than the inefficiency of the companies which face a subsidy policy based on cost norms. Our analysis gives, however, no significant differences in the efficiency between privately owned bus companies and publicly owned bus operators, and shows only minor economies of scale.     

The characteristic velocity stability indicator for passenger cars

Driver assistance systems have received increased attention as market demands have pushed for improved automotive safety. These systems are designed to aid the driver by preventing any unstable or unpredictable vehicle behaviour. One global indicator for stability and driving conditions could help to manage the control algorithms and driver warning subroutines. Another problem which could be solved by a precise driving situation indicator is evaluating new vehicles during test drives. After a short introduction to a linear lateral vehicle model, an analytical approach for an online calculation of different driving conditions (i.e., stability, understeering, oversteering, and neutralsteering) is given. A characteristic velocity stability indicator is defined, which allows online computation of the present driving condition. Results are then checked against real measurements of a test vehicle.     

Analysis of the evolvement of contact wire wear irregularity in railway catenary based on historical data

This paper studies the evolvement of the wear irregularity of contact wire using wire thickness data measured yearly from a section of railway catenary. The power spectral density and time–frequency representation based on the wavelet transform are employed for data analysis, with an emphasis on local wear irregularities that are crucial for contact wire condition assessment. To investigate the cause of wear irregularity evolvement and the mutual influence with the pantograph–catenary dynamic interaction, simulations considering the influence of wear irregularity are carried out based on the finite element method. Analyses of the actual wear irregularities and the dynamic contact force under singular and complex wear irregularities are performed. Although the wear irregularity has limited impact on the pantograph–catenary interaction, it can induce the vibration of pantograph and contact wire that will lead to a notable increase of contact force standard deviation. The evolvement of wear irregularity is closely associated with the span length and dropper distribution of catenary structure and the running direction of pantograph. In addition, it is found feasible to detect the wear irregularity based on contact force, on condition that the sampling frequency is high enough to reflect the indicative frequencies.     

Diagnosis Methods for Electronic Controlled Vehicles

The development of automotive systems shows an increasing number of sensors, actuators and microelectronic controllers, partially for active driver assistance. However, electronic and electrical components have quite different failure behavior and in general lower reliability than mechanical components. On the other side microcomputers can also be used for fault detection and diagnosis. The contribution therefore shows how model-based fault detection and diagnosis methods together with few available measurements can be applied for automobiles. After an introduction, a short summary is given for fault detection and diagnosis methods, especially for model-based methods. Then some research results are shown, like the fault detection and diagnosis of an electromechanical throttle actuator, a suspension system and the lateral behavior of a passenger car. Finally, methods for fault-tolerant sensors and actuators are discussed which are required for drive-by-wire systems.