Demand-Responsive Transportation Vehicle Routing Optimization Based on Two-Stage Method

Demand-responsive transportation(DRT)is a flexible passenger service designed to enhance road efficiency,reduce peak-hour traffic,and boost passenger satisfaction.However,existing optimization methods for initial passenger requests fall short in addressing real-time passenger needs.Consequently,there is a need to develop realtime DRT route optimization methods that integrate both initial and real-time requests.This paper presents a twostage,multi-objective optimization model for DRT vehicle scheduling.The first stage involves an initial scheduling model aimed at minimizing vehicle configuration,and operational,and CO_(2)emission costs while ensuring passenger satisfaction.The second stage develops a real-time scheduling model to minimize additional operational costs,penalties for time window violations,and costs due to rejected passengers,thereby addressing real-time demands.Additionally,an enhanced genetic algorithm based on Non-dominated Sorting Genetic Algorithm-II(NSGA-II)is designed,incorporating multiple crossover points to accelerate convergence and improve solution efficiency.The proposed scheduling model is validated using a real network in Shanghai.Results indicate that realtime scheduling can serve more passengers,and improve vehicle utilization and occupancy rates,with only a minor increase in total operational costs.Compared to the traditional NSGA-II algorithm,the improved version enhances convergence speed by 31.7%and solution speed by 4.8%.The proposed model and algorithm offer both theoretical and practical guidance for real-world DRT scheduling.

Research on the stability of virtual coupling train formation based on a PID controller under the influence of time delay

As the latest research direction of train-to-train communication,virtual coupling train formation technology has attracted the attention of many scholars.This paper studies the influence of time delay on the formation of virtual coupled trains.We proposed a distributed PID controller,which means that trains can still form a stable fleet operation under the influence of communication delay and control delay.After modelling and analysis,the research uses Matlab to conduct simulation,involving two sets of experiments.Factors including speed,acceleration,position,position error,expected distance between adjacent trains and actual distance between adjacent trains are simulated.The results demonstrate that the distributed PID controller can effectively control the impact of time delay on the virtual coupling fleet.

Vibration of Axle Box from Wheel Diameter Difference in Vehicle

The wheel diameter difference would worsen the dynamic performance and affect the safety of the rail vehicle.Therefore,it is necessary to detect wheel diameter difference while the train is operating.However,several existing detection methods can’t accurately detect and diagnose the wheel diameter difference under highspeed running environment.In this study,a new method of detecting wheel diameter difference was proposed for high speed rail vehicle.The wheel diameter difference would be diagnosed by the amplitude and frequency of vibration impact on the axle box.Firstly,the dynamic model with varying wheel diameters was established in SIMPACK,and LMA tread was used in high-speed rail vehicles.Then,the simulation results of rail vehicle dynamic performance were compared under different wheel diameter differences.After that,the relationship between axle box vibration and wheel diameter difference was used to demonstrate the feasibility of this detection technology.Finally,comparing and analyzing the simulation results of vibration obtained by matching treads with different wheel diameters,it shows that by increasing the wheel diameter difference,the longitudinal and lateral impacts on axle boxes increase asymmetrically,and the amplitude and the frequency become more evident.Therefore,this paper presents a technical scheme of online measuring wheel diameter difference by monitoring the vibration of the axle box.

Toxicity effects of disinfection byproduct chloroacetic acid to Microcystis aeruginosa: Cytotoxicity and mechanisms

Chlorine-based disinfectants are widely used for disinfection in wastewater treatment.The mechanism of the effects of chlorinated disinfection by-products on cyanobacteria was unclear.Herein,the physiological effects of chloroacetic acid(CAA)on Microcystis aeruginosa(M.aeruginosa),including acute toxicity,oxidative stress,apoptosis,production of microcystin-LR(MC-LR),and the microcystin transportation-related gene mcyH transcript abundance have been investigated.CAA exposure resulted in a significant change in the cell ultrastructure,including thylakoid damage,disappearance of nucleoid,production of gas vacuoles,increase in starch granule,accumulation of lipid droplets,and disruption of cytoplasm membranes.Meanwhile,the apoptosis rate of M.aeruginosa increased with CAA concentration.The production of MC-LR was affected by CAA,and the transcript abundance of mcyH decreased.Our results suggested that CAA poses acute toxicity to M.aeruginosa,and it could cause oxidative damage,stimulate MC-LR production,and damage cell ultrastructure.This study may provide information about the minimum concentration of CAA in the water environment,which is safe for aquatic organisms,especially during the global coronavirus disease 2019 pandemic period.

Research on virtual coupling technology in rail transit train collision protection

In the research on the new generation of intelligent rail transit system,the prevention of train collision accidents is still a focus.Virtual coupling technology controls the running speed and interval distance of two or more trains cooperatively through Trainto-Train(T2T)direct communication technology.The aim is to form a coordinated logical system and jointly complete the train control and dispatching.In this paper,a virtual coupling train formation control method based on the model predictive control(MPC)framework is proposed.From the establishment of the virtual coupling system,the construction of an MPC model and decoupling method,how to integrate virtual coupling technology into the rail transit train collision protection is studied.The safety and reliability of the system are calculated through fault tree and the method of constructing reliability function.The research shows that if virtual coupling technology is used for train collision protection,the overall safety and reliability of the train control system is improved.