1,721,128 research outputs found
Coupling of microscopic and macroscopic traffic models at boundaries
No full textIn this paper, we investigate boundary coupling of microscopic-macroscopic models in the study of traffic flows. We propose a definition of solution through coupling of initial boundary value problems for the discrete Follow the Leader model and the fluidodynamic second-order Aw-Rascle-Zhang model in the two quadrants t>0; x0. Moreover, new connections between these two models are pointed out, showing another fluidodynamical interpretation of the microscopic Follow the Leader model
Special bang--bang solutions of nonlinear control problems
No full textWe prove the existence of bang-bang controls for a class of nonlinear control systems in the plane
Psychological insights
No full textThe aim of this chapter is to take another point of view in the modeling of the crowd. Namely, here we report some approaches focusing on pedestrians as individuals. Then it is of paramount importance to take into account the psychological aspects of the problem, distinguishing moving humans from “particles” or even from self-propelled agents (e.g., birds). Such psychological components show up both in the choice of walking strategies and preferences and in interaction rules with other pedestrians. The focus will be mainly on investigations addressing the behavior of the single pedestrian moving in an organized environment. Moreover, we will discuss some models proposed by works in different fields, not limited to psychology. However, the latter are more of qualitative nature, as opposed to mathematically advanced ones discussed in Chaps. 4 and 5. Then we will deal with experiments and measurements. In particular we will discuss how the experimental setting influences results because of expected psychological bias. Also a view on the most used measurement tools is included, since this may also affect the perception of experiment participants. Finally, we will compare some experimental setting, showing how sensitive to them measurements can be
Generalizations of the multiscale approach
No full textIn this chapter we present some natural generalizations of the multiscale approach described in Chap. 5. In most of the cases, the following ideas are not yet fully developed. Nevertheless, they give some interesting directions for future research, from theoretical, numerical, and applied point of view
Model-based assessment of the impact of driver-assist vehicles using kinetic theory
Full text linkIn this paper, we consider a kinetic description of follow-the-leader traffic models, which we use to study the effect of vehicle-wise driver-assist control strategies at various scales, from that of the local traffic up to that of the macroscopic stream of vehicles. We provide theoretical evidence of the fact that some typical control strategies, such as the alignment of the speeds and the optimisation of the time headways, impact on the local traffic features (for instance, the speed and headway dispersion responsible for local traffic instabilities) but have virtually no effect on the observable macroscopic traffic trends (for instance, the flux/throughput of vehicles). This unobvious conclusion, which is in very nice agreement with recent field studies on autonomous vehicles, suggests that the kinetic approach may be a valid tool for an organic multiscale investigation and possibly the design of driver-assist algorithms
A Fast Computation Method for Time-scale Signal Denoising
No full textThis paper presents a novel and fast scheme for signal denoising in the wavelet domain. It exploits the time scale structure of the wavelet coefficients by modeling them as superposition of simple atoms, whose spreading in the time scale plane formally is the solution of a couple of differential equations. In this paper, we will show how the numerical solution of such equations can be avoided leading to a speed up of the scale linking computation. This result is achieved through a suitable projection space of the wavelet local extrema, requiring just least squares and filtering operations. Intensive experimental results show the competitive performances of the proposed approach in terms of signal to noise ratio (SNR), visual quality and computing time
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