Search

Cooperative adaptative cruise controls and variable speed limit are gaining notoriety in recent years to fulfill the aim of reducing traffic congestions. Improvements in the management of hazardous materials, combined with these technologies, can reduce damages caused by congestions, mitigate risks to human health, and avoid environmental leakage. Drivers' behaviors are directly influenced by human beings' different reactions. Therefore, the variance in traffic produces shockwaves, rippling traffic waves, and a reduction of the traffic flow capacity. This paper aims to present adaptative optimal control of nonlinear systems simulation as a tool to prove the effects of the predictions according to drivers' behavior. Furthermore, it supports the decision making of hazardous material traffic management. Traffic engineering and queuing theory are also addressed. [ABSTRACT FROM AUTHOR]

Software-Defined Networking (SDN) has emerged as an innovative networking method that offers effective management and remarkable flexibility. However, current SDN-based solutions primarily focus on static networks or concentrate on backbone networks, where network dynamics have minimal impact. The existing methods for placing flow entries in Software-Defined Networking (SDN)-based Internet of Things (IoT) systems exhibit shortcomings in accurately predicting outcomes and efficiently reducing table misses and associated performance metrics. This research introduces a new approach, specifically the mobility-aware adaptive flow entry placement scheme for SDN-based Internet of Things (IoT) environments, to address the mobility aspect of networks. The proposed scheme utilizes the Q-learning algorithm to predict the next possible location of end devices, while the cost-sensitive AdaBoost algorithm is employed to select heavy and active flows. As a result, efficient flow rules for incoming flows can be dynamically implemented without controller intervention. Extensive computer simulations demonstrate that this approach significantly enhances match probability and prediction accuracy while concurrently reducing the number of table misses and resource expenditure compared to existing schemes. [ABSTRACT FROM AUTHOR]

Currently, model tests are increasingly being used to simulate the construction of mountain tunnels, but the support structure of the model tests does not show the composite lining, and the force laws of the composite lining are not yet clear. In this research, the force variation of composite lining under three cases in model tests of deep-buried tunnels were carried out with the surrounding rock grade and installation time as the variation factors. The test results reveal that: (1) The suitable method to reduce the contact load between the secondary lining and primary support is to enhance the primary support in the soft and weak surrounding rock. Correspondingly, for Class III surrounding rock and better quality of surrounding rock, the primary support can lag behind the excavation face a certain distance. (2) The axial forces of the bolts tend to rise with concentration of 0.4 kN–0.7 kN after the secondary lining was installed. (3) With or without two to three excavation cycles delayed, the load sharing ratio of the secondary lining of the Class III surrounding rock is less than 10%. Finally, the numerical simulation verifies the feasibility of the model tests. [ABSTRACT FROM AUTHOR]

The aerodynamic braking has become an attractive option with the continuous improvement of train speeds. The study aims to obtain the optimal opening angles of multiple sets of braking plates for the maglev train. Therefore, a multi-objective optimization method is adopted to decrease the series interference effect between multiple sets of plates. And the computational fluid dynamics method, based on the 3-D, RANS method and SST k-ω turbulence model, is employed to get the initial and iterative data. Firstly, the aerodynamic drag and lift are analysed, as well as the pressure and velocity distribution of the flow field with the braking plates open at 75°. Then, the aerodynamic forces of each braking plate pre and post optimization are compared. Finally, the correlation between each set of braking plates and the optimized objective is analysed. It is found from the results that the aerodynamic drag and lift of the train have significant differences with or without multiple sets of braking plates. Additionally, the design variable corresponding to the number of iterations of 89 is taken as the relative optimal solution, and its opening angles of braking plates (B2-B5) are 87.41°, 87.85°, 87.41°, and 89.88°, respectively. The results are expected to provide a reference for the opening angles design scheme for the future engineering application of high-speed maglev train braking technology. [ABSTRACT FROM AUTHOR]

The general expectation is that the traffic in the cities will be almost optimal when the collective behaviour of autonomous vehicles will determine the traffic. Each member of the collective of autonomous vehicles tries to adapt to the changing environment, therefore together they execute decentralised autonomous adaptation by exploiting real-time information about their environment. The routing of these vehicles needs proper computer science models to be able to develop the best information technology for their control. We review different traffic flow models in computer science, and we evaluate their usefulness and applicability to autonomous vehicles. The classical game theory model implies flow level decision making in route selection. Non-cooperative autonomous vehicles may produce unwanted traffic patterns. Improved decentralised autonomous adaptation techniques try to establish some kind of coordination among autonomous vehicles, mainly through intention awareness. The aggregation of the intentions of autonomous vehicles may help to predict future traffic situations. The novel intention-aware online routing game model points out that intention-awareness helps to avoid that the traffic generated by autonomous vehicles be worse than the traffic indicated by classical traffic flow models. The review helps to make the first steps towards research on global level control of autonomous vehicles by highlighting the strengths and weaknesses of the different formal models. The review also highlights the importance of research on intention-awareness and intention-aware traffic flow prediction methods. [ABSTRACT FROM AUTHOR]

In this paper, the bifurcation and chaotic threshold of Duffing oscillator with fractional-order delayed feedback control is studied. The fractional-order delayed feedback control is equivalent to the approximate integer-order control. It is found that the fractional-order delayed feedback control has the function of displacement feedback and velocity feedback. Then, the analytically necessary condition for generating chaos in Duffing oscillator with fractional-order delayed feedback control is obtained by Melnikov method. The accuracy of the analytically necessary condition by Melnikov method is verified by numerical simulation and the largest Lyapunov exponents of the system. From the analysis of the numerical simulation results, it is found that there are two paths leading to the chaos after period-doubling bifurcations due to different initial values in Duffing oscillator with fractional-order delayed feedback. Finally, the influence of the parameters of the fractional-order delayed feedback control on bifurcation and chaos is analyzed. The increase of the fractional-order delayed feedback gain will resist the generation of chaos. Both time delay and the fractional-order affect the threshold of chaos in the form of trigonometric functions. The better control performance in the system can be obtained by choosing the reasonable fractional order and time delay. Those results present some new system characteristics which provide theoretic guidance to design and control of this kind system. [ABSTRACT FROM AUTHOR]

In improving the comfort of vehicles, air spring suspension has obvious advantages, but under the action of transient impact load, the damping effect of air spring suspension is not ideal due to the hysteresis phenomenon of air spring stiffness regulation. In order to analyze the mechanism of the above problems, the dynamic mathematical model and simulation model of air spring suspension are established. And the nonlinear characteristic of the elastic characteristics of the suspension is expounded theoretically. The simulation results show that the stiffness of the air spring increases with the increase of the transient impact load, and the peak value of the transfer function increases and moves to high frequency near the natural frequency of the body. And the peak value and the peak frequency of the transfer function only change slightly near the natural frequency of the wheel. There are bifurcations and secondary shocks at the wave crest of the acceleration curve under impact loads of 30 mm and 50 mm. The type of research can provide theoretical basis and reference for the design, analysis and optimization of air suspension. [ABSTRACT FROM AUTHOR]

As a vital road construction machine, the bridge erecting machine works in a very complex environment. The brake as an important link to maintain the safety and stability of the bridge erecting machine, it will have serious consequences if it is failed. Establishing the brake simulation model and specifying the fault characteristics according to the actual operation status will make it more efficient to find the cause of faults and maintain the safety of machine for a long time. A simulation model of brake of the bridge erecting machine was established by Adams. The brake arms and center axis with obvious data characteristics were flexibly processed, and finite elements were analysed using Abaqus. To verify the accuracy of simulation models, rectangular rosettes were applied to special geometric points, and the strain data were gathered by using the DH3816N collector and compared with the simulation model. The Adams kinematic simulation model was used to simulate the actual operating conditions by the experiment of the disc springs. Two typical fault phenomena were selected: reduced insufficient of disc spring and oil pressure, and two fault characteristics were extracted: variation of the brake shoe clearance and variation of the braking system pressure. When the brake generates the fault characteristics, the normal operation of the brake will not be affected if the fault characteristics are in the first stage. When the fault characteristics are beyond the critical threshold, the faults phenomena of the brake are generated. The results of the simulation experiments proved that the method of using the simulation model to extract the fault characteristics of the braking system and distinguish the causes of the fault was feasible. [ABSTRACT FROM AUTHOR]

The droplet impact on solid surfaces is a popular research topic in which many researchers focus on stationary surfaces, only a few researches have been conducted for moving surfaces. In this paper, a high-speed photography-based droplet impact experimental platform and a VOF-based numerical simulation model are built to study the morphology of motion of a droplet after it impacted a horizontal uniformly moving surface. In the present study, the tangential and normal Weber numbers range within 70. This is because at such low Weber numbers the droplets initially spread to their maximum diameter after impacting the moving surfaces and subsequently start to rebound. The studies have confirmed that the maximum spreading factor of the droplet increases linearly with the tangential Weber number, and the spreading time increases as well. The maximum spreading factor of the droplet increases nonlinearly as a function of the normal Weber number and corresponding time initially increases and then decreases. Finally, the expression for the maximum spreading factor is fitted according to its correlation with the We number. [ABSTRACT FROM AUTHOR]