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A macroscopic traffic flow model, called the switching-mode model (SMM), has been derived from the cell transmission model (CTM) and then applied to the estimation of traffic densities at unmonitored locations along a highway. The SMM is a hybrid system that switches among different sets of linear difference equations, or modes, depending on the mainline(More)
  • Isabel Mendizabal, Cristina Valente, Alfredo Gusmão, Cíntia Alves, Verónica Gomes, Ana Goios +7 others
  • 2011
Previous genetic, anthropological and linguistic studies have shown that Roma (Gypsies) constitute a founder population dispersed throughout Europe whose origins might be traced to the Indian subcontinent. Linguistic and anthropological evidence point to Indo-Aryan ethnic groups from North-western India as the ancestral parental population of Roma.(More)
Sperm, navigating in a chemical gradient, are exposed to a periodic stream of chemoattractant molecules. The periodic stimulation entrains Ca(2+) oscillations that control looping steering responses. It is not known how sperm sample chemoattractant molecules during periodic stimulation and adjust their sensitivity. We report that sea urchin sperm sampled(More)
Sperm require a sense of direction to locate the egg for fertilization. They follow gradients of chemical and physical cues provided by the egg or the oviduct. However, the principles underlying three-dimensional (3D) navigation in chemical landscapes are unknown. Here using holographic microscopy and optochemical techniques, we track sea urchin sperm(More)
In this paper, second-order macroscopic vehicle traffic flow models are discussed from the perspective of their capability to reproduce stable and unstable traffic flow behaviors observed in real traffic. To achieve this goal, a nonlinear traffic flow stability criterion is derived using a wavefront expansion technique. Qualitative relationships between(More)
SUMMARY This paper addresses the problem of designing safe controllers for vehicle manuevering in Automated Ž. Highway Systems AHS in which traffic is organized into platoons of closely spaced vehicles. Conditions to achieve safe platooning under normal modes of operation are investigated. The notion of safety is related with the absence of collisions that(More)
An adaptive control scheme for emergency braking of vehicles is designed based on a LuGre dynamic model for the tire-road friction. The wheel angular speed and longitudinal vehicle acceleration information are used to design a fast convergence observer to estimate the vehicle velocity and the internal state of the friction model. The unknown parameters of(More)
SUMMARY This paper presents the design of a velocity tracking controller for safe vehicle maneuvering in Ž. Automated Highway Systems AHS in which traffic is organized into platoons of closely spaced vehicles. The notion of safety is related to the absence of collisions that exceed a given relative velocity threshold. In a companion paper, state dependent(More)
Controls for the link layer in the Automated Highway System (AHS) hierarchy proposed in the Partners for Advanced Transit and Highways (PATH) are developed. The link layer is modeled using vehicle conservation flow models. Desired traffic conditions on the highway are given by a pair of density and velocity profiles which are assumed to be consistent with(More)