Modelling of the shape of railway transition curves from the point of view of passenger comfort

In the past, railway transition curves were not used. Instead of it, a simple connection of the straight track and circular arc was applied. Nowadays, such simplicity is not allowed due to the increasing vehicle operating velocities. It is mainly visible in the high-speed train lines, where long curves are used. The article aims to develop a new shape of railway transition curves for which passenger travel comfort will be as high as possible. Considerations in this paper concern the polynomials of 9th- and 11th-degrees, which were adopted to the mathematical model of the mentioned shape of curves. The study's authors applied a 2-axle rail vehicle model combined with mathematically understood optimisation methods. The advanced vehicle model can better assign the dynamical properties of railway transition curves to freight and passenger vehicles. The mentioned model was adopted to simulate rail vehicle movement in both cases of the shape of transition curves and the shape of circular arc (for comparison of the results). Passenger comfort, described by European Standard EN 12299, was used as the assessment criterion. The work showed that the method using the 2-axle railway vehicle model combined with mathematically understood optimisation works correctly, and the optimisation of the transition curve shape is possible. The current study showed that the 3rd-degree parabola (the shape of the curve traditionally used in railway engineering) is not always the optimum shape. In many cases (especially for the long curves), the optimum shape of curves is between the standard transition curves and the linear curvature of the 3rd-degree parabola. The new shapes of the railway transition curves obtained when the passenger comfort is taken into account result in new railway transition curves shapes. In the authors' opinion, the results presented in the current work are a novelty in optimisation and the properties assessment of railway transition curves.

Estimating Road Vehicle Instantaneous Fuel Consumption by Aerial Traffic Observation with a Multi-Rotor Drone

This study presents a preliminary approach to estimate instantaneous fuel consumption base on image processing from aerial observation using a multi-rotor drone. A drone was deployed over an actual road traffic to capture images of vehicle activities and feed into a program that was developed in this study. The program identifies and tracks the vehicle activities using pixel-based adaptive approach. The vehicle activities were then processed into variables as an input for the generic vehicle model. Coupled with model constants, the generic vehicle model then estimates the instantaneous fuel consumption and CO2 emission and tags the estimated results on the tracked vehicle on the program user-interface. In comparison with the actual experimental measurements, the estimated instantaneous fuel consumption shows a trend with correlation coefficient of 0.741 with higher total fuel usage by 10.6%. The estimation results were useful to map the distribution of fuel consumption over the routes of the observed area in relation to the natural traffic.

Design and Analysis of Road Load Detection Machine Based on Computer Technology

In this paper, an experimental device is designed for measuring vehicle dynamic load, the structure and stress of the equipment are analyzed by computer technology. The device design mainly includes vehicle, road surface, vehicle transmission, and control [1]. The vehicle is designed based on a 2-DOF vehicle model, the road is designed based on the Pasternak foundation model, and the control mainly uses a single-chip microcomputer. The dynamic response of vehicles to the road at different speeds is analyzed through the experiment [2].

Rollover Prevention Control for Autonomous Electric Road Sweeper

This paper presents a method to prevent the rollover of autonomous electric road sweepers (AERS). AERS have an articulated frame steering (AFS) mechanism. Moreover, the heights of the center of gravity of the front and rear bodies are high. As such, they are prone to rolling over at low speeds and at small articulation angles. A bicycle model with a nonlinear tire model was used as a vehicle model for AERS. Using that vehicle model, path tracking and speed controllers were designed in order to follow a predefined path and speed profile, respectively. To check the rollover propensity of AERS, load transfer ratio (LTR) based the rollover analysis was completed. Based on the results of the analysis, a rollover prevention scheme was proposed. To validate the proposed scheme, a simulation was conducted using a U-shaped path under constant speed conditions. From the simulation, it was shown that the proposed scheme is effective in preventing AERS from rolling over.

Influence of Flanks on Resistance Performance of High-Speed Amphibious Vehicle

In order to reduce the additional resistance of high-speed amphibious vehicles, Flanks are designed on the concave grooves. As a new drag reduction attachment, the principle of Flanks is analyzed and discussed in detail. In this paper, the HSAV model and Flanks coupling resistance tests are performed based on the Reynolds-averaged Navier–Stokes method and SST k−ω model. The accuracy of the numerical approach is verified by a series of towing tests. Results show that with a fixed installation angle and invariable characteristic parameters, Flanks can significantly reduce the total resistance at high speed, with a maximum drag reduction of 16%. In the meantime, Flanks also affect the attitude and flow field of the vehicle, consequently affecting the resistance composition and the sailing condition. A vehicle model self-propulsion test is designed and carried out, and it qualitatively verifies the drag reduction effect of the Flanks at high speed.

Delay margin comparison in a velocity-only versus headway-only connected vehicle model

Two different connected vehicle models are considered: one based on only using velocity measurements and the other using only headway, where each model is affected by delays due to human reaction times and sensing and communication lines. The presence of delays is established between any two vehicles that are neighbors as determined by the underlying network topology. The main focus here is to put light into our understanding of how much of time delay can the equilibrium of these models tolerate before becoming unstable. To this end, we compute, using the parallel processing computational tool Delay Margin Finder (parDMF), the delay margin of the equilibrium dynamics and discuss design trade-offs. We report that delay margin in the headway-only model is much less sensitive against the presence/absence of links in the network and that this model can have larger delay margin when larger number of vehicles are capable of communicating with other vehicles in the platoon.