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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]

Traffic is highly influenced by network structure and human behaviour. Small changes in the human behaviour can lead to huge changes in the load of a traffic network. Current transportation models do not, and most of them cannot, research such random behaviour but always calculate a steady state. In our multi-agent transport simulation, we frequently observe seemingly random “network breakdowns”, huge traffic jams that spread over a big part of the network, making a normal traffic flow impossible. This paper describes the investigations that were performed on the results of our large-scale multi-agent transport simulations in an attempt to contribute to the better understanding of the dynamic processes in such simulations and, hopefully, better understanding and modelling of the real-world. [ABSTRACT FROM AUTHOR]

The use of modeling and simulation aids in deriving many decisions related to transportation planning and traffic operations. Representing the real systems via simulation allows exploring system behavior in an articulated way, which is often impossible in the real world. In this paper, a simulation-based framework is presented to evaluate the impact of congestion charging on daily activity plans of the individuals. Personal decision to accept the congestion charges is evaluated by comparing the value of time with congestion charge. Value of time varies throughout the day depending upon the time pressure at any moment exerted by preceding and succeeding activities. Time pressure during an activity increases if available time for that activity is insufficient to attain the perceived utility. Daily activities in the schedules are modeled using bell-shaped marginal utility that results in sigmoid utility. A model is presented which derives the activity-specific parameters of the marginal utility function for the specific individual. To examine value of time of each person, the congestion charging is applied where personal willingness-to-pay is determined by comparing the ratios of cost to utility for original and adapted schedules. A large-scaled microsimulation of the modeled framework is used to simulate the whole population, which is created by FEATHERS, an operational activity-based model for Flanders, Belgium. The results of the simulation show that the number of individuals who avoid the congestion charges by adapting their schedules is almost three times the number of those who agree to pay it. The proposed framework can be useful to evaluate the tradeoff between value of time and costs where flexibility in selection of time defines the variability in cost. [ABSTRACT FROM AUTHOR]

This paper describes a multi-agent coordination mechanism applied to intersection simulation situations. In a goal of urban traffic simulation, we must consider the dynamic interactions between autonomous vehicles. The field of multi-agent systems provides us some studies for such systems, in particular on the coordination mechanisms. Conflicts between vehicles (i.e. agents) are very frequent in such applications, and they may cause deadlocks, particularly at intersections such as crossroads. Our approach is based on the solving of two player games/decision matrices which characterize three basic situations. An aggregation method generalizes to n-player games for complex crossroads. The objective of this approach consists in searching basic two-player matrices for solving n-agent problems. To explain the principle, we describe our approach for a particular case of crossroad with three agents. Finally, the obtained results have been examined via a tool of road traffic simulation. ARCHISIM. We assume also that the global traffic replicates the behavior of agents in different situations. [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]

The current study aims to investigate the effectiveness of two different designs of helmet interior cushion, (Helmet 1: strap-netting; Helmet 2: Oregon Aero foam-padding), and the effect of the impact directions on the helmeted head during ballistic impact. Series of ballistic impact simulations (frontal, lateral, rear, and top) of a full-metal-jacketed bullet were performed on a validated finite element head model equipped with the two helmets, to assess the severity of head injuries sustained in ballistic impacts using both head kinematics and biomechanical metrics. Benchmarking with experimental ventricular and intracranial pressures showed that there is good agreement between the simulations and experiments. In terms of extracranial injuries, top impact had the highest skull stress, still without fracturing the skull. In regard to intracranial injuries, both the lateral and rear impacts generally gave the highest principal strains as well as highest shear strains, which exceed the injury thresholds. Off-cushion impacts were found to be at higher risk of intracranial injuries. The study also showed that the Oregon Aero foam pads helped to reduce impact forces. It also suggested that more padding inserts of smaller size may offer better protection. This provides some insights on future's helmet design against ballistic threats. [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]