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Volume 1, Issue 1, 2022

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Active control is essential for EMS maglev trains to achieve stable suspension. Currently, the main line's suspension performs well, but in areas with low track stiffness, such as the garage, turnouts, and other lines, unexpected coupling vibration is more likely to occur. Control parameters, vehicle parameters, and rail parameters are all closely related to this phenomenon. In this study, the vehicle-rail coupling dynamic equation with secondary suspension system is first established, and used to disclose the effects of different parameters on the electromagnet-rail coupling vibration of the EMS maglev train. Next, the authors adopted the proportional-derivative (PD) controller, and proposed the concept of maglev train control frequency. Next, a general simulation model was established based on the MATLAB/Simulink, and numerical simulation was carried out to reveal how the secondary suspension frequency, the control frequency and the rail frequency affect the electromagnet-rail coupling vibration. The research results provide a reference for the design of maglev trains, controllers, and tracks, laying a theoretical basis for the maintenance of maglev commercial lines.

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Unmanned ground vehicles (UGVs) and quadrotor unmanned aerial vehicles (UAVs) can work together to solve challenges like intelligent transportation, thanks to their excellent performance complements in perception, loading, and endurance. This study presents a UAV-UGV system cooperative control mechanism. To achieve collaborative trajectory tracking, the leader-follower strategy based on a centralized control structure is firstly established in conjunction with the application scenario. The fuzzy robust controller is created to control the quadrotor UAV and improve attitude stability. Meanwhile, the UGV's controller uses the pure pursuit algorithm and a proportional integral derivative (PID) controller. In order to evaluate the cooperative control strategy and algorithm, the UAV-UGV experimental platform is set up based on the QDrone and QCar, and the experimental results show the viability of the suggested plan.

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The operating speed is the average value of the speed of traffic flow under normal conditions, i.e., the conditions of mutual interference of traffic participants. The operating speed serves as a gauge for how well a given roadway is performing under the applicable traffic conditions. All key decisions in the management of the growth and utilization of a road network, including planning, designing, evaluating, and implementing road projects, depend on accurate measures of capacity and level of service. This paper aims to develop a recommended model for operating speed on two-lane roads under local conditions by analyzing the operating speeds of the traffic flow on representative sections of such roads. Through the modeling process, the values of the 85th percentile of the operating speed were determined, and compared with relevant studies. The results show that the authors have successfully modeled operating speeds as a function of longitudinal gradient in local conditions on two-lane roads.

Open Access
Research article
Field Tests and Analyses on Running Stability of Fenghuang Medium and Low Speed Maglev Train
yuheng ai ,
junqi xu ,
guobin lin ,
xiao liang ,
sumei wang ,
yang lu ,
chen chen
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Available online: 11-04-2022

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Multiple field tests were carried out on the Fenghuang medium and low speed maglev train. During the tests, the authors collected the vibration data of train carriage and suspension frames under no-load (AW0). Next, the stability of the maglev train under corresponding conditions was investigated, using indices like weighted RMS acceleration (ISO 2631) and Sperling index. Through the in-depth analyses, it was concluded that the maglev train runs smoothly, and the passengers on the train generally feel comfortable.

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Thanks to its superb curve negotiation characteristics, the side-suspended high-temperature superconducting (SS-HTS) maglev system boasts a great potential for high-speed transportation. The SS-HTS maglev system, however, significantly differs in suspension features from the conventional maglev system because of its unique side-suspended structure. To improve suspension performance, the field-cooling technique of superconducting bulks in the SS-HTS system was investigated through a number of experiments. To fit the experimental data, the authors proposed the mathematical models of the levitation and guidance forces as well as the optimal field-cooling position. Furthermore, a dynamic model was developed for the SS-HTS maglev vehicle operating on a curve line, and the curve negotiation characteristics were simulated for the maglev vehicle. Finally, the stability of the curve negotiation for the SS-HTS system was assessed using the Sperling index. The results show that the SS-HTS maglev vehicle can pass over bends at a certain speed. The authors also recommended the suspension parameters the maglev vehicle.

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Road maintenance is essential to the growth of the transportation infrastructure and, thereby, has a big impact on a nation's overall economic stability and prosperity. It is impossible to simultaneously monitor and maintain the entire network. As a result, transportation authorities are eager to develop scientific foundations for assessing the importance of maintenance tasks within the network of roads. Hence, pavement assessment methods are needed to establish the priorities and achieving the most convenient level of service. In this study, a road stretch was assessed using the sixteen criteria in the Distress Identification Manual for pavement defects, using pavement condition index (PCI) and multi-criteria decision-making models (MCDM). The two methods were compared to determine the possibility of using MCDM. The study came to the conclusion that MCDM is reliable in assessing pavement performance because both methods indicated that the road pavement is deteriorating.

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Due to their advantages in hovering, takeoff and landing adaptability, maneuverability, and other factors, rotary-wing unmanned aerial vehicles (UAVs) are widely applied across many different fields. The UAVs' design and configuration can be quite flexible to fit diverse operation conditions. The major goal of innovations in rotary-wing UAVs is to lower operating risk and expense by optimizing payload and structure layout. This study examines three aspects of rotary-wing UAV design and evolution: the number and arrangement of rotors, hybrid-wing-based UAVs, and configuration and loading structures. The most current advancements of UAV applications in crucial industries, including agriculture, fire rescue, inspection and monitoring, and aerial logistics, are then thoroughly examined. Finally, the authors discussed the prospective uses for rotary-wing UAV design in the future.

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