A macroscopic model for platooning in highway traffic

We consider a model describing the presence of a platoon of vehicles moving in the traffic flow. The model consists of a coupled PDE-ODE system describing the interaction between the platoon and the surrounding traffic flow. The scalar conservation law takes into account the main traffic evolution, while the ODEs describe the trajectories of the initial and final points of the platoon, whose length can vary in time. The presence of the platoon acts as a road capacity reduction, resulting in a space-time discontinuous flux function. We describe the solutions of Riemann problems and design a finite volume numerical scheme sharply capturing non-classical discontinuities. Some numerical tests are presented to show the effectiveness of the method

Simple (γ, δ) algebras are associative

AbstractA (γ, δ) algebra over a field F is a nonassociative algebra satisfying an identity of the form, (a, b, c) + γ(b, a, c) + δ(c, a, b) = 0, for fixed γ, δ ϵ F, and γ2 − δ2 + δ = 1. We assume that F is of characteristic ≠ 2, ≠ 3; however, we do not assume that the algebra is finite-dimensional over F. We show that any simple (γ, δ) algebra is associative with the possible exception of the cases (± 1, 0) and (1, 1). The approach used in this paper is to represent the identities by matrices by way of the group algebra representation. This enables us to manipulate identities by the well-known techniques of matrix theory

Simple (γ, δ) algebras are associative

AbstractA (γ, δ) algebra over a field F is a nonassociative algebra satisfying an identity of the form, (a, b, c) + γ(b, a, c) + δ(c, a, b) = 0, for fixed γ, δ ϵ F, and γ2 − δ2 + δ = 1. We assume that F is of characteristic ≠ 2, ≠ 3; however, we do not assume that the algebra is finite-dimensional over F. We show that any simple (γ, δ) algebra is associative with the possible exception of the cases (± 1, 0) and (1, 1). The approach used in this paper is to represent the identities by matrices by way of the group algebra representation. This enables us to manipulate identities by the well-known techniques of matrix theory

On Prime Right Alternative Algebras and Alternators

We study subvarieties of the variety of right alternative algebras over a field of characteristic t2,t3 such that the defining identities of the variety force the span of the alternators to be an ideal and do not force an algebra with identity element to be alternative. We call a member of such a variety a right alternative alternator ideal algebra. We characterize the algebras of this subvariety by finding an identity which holds if and only if an algebra belongs to the subvariety. We use this identity to prove that if R is a prime, right alternative alternator ideal algebra with an idempotent e to,tl such that (e,e,R) =O, then either R is alternative or R belongs to one of four exceptional varieties

The use of inhaled corticosteroid in preschool wheezers: what's the point today?

Among the preschool children who wheeze two different groups can be identify: children who have a viral infection and those who respond to multiple triggers, such as exercise or allergens

CMB Polarization Systematics, Cosmological Birefringence and the Gravitational Waves Background

Cosmic Microwave Background experiments must achieve very accurate calibration of their polarization reference frame to avoid biasing the cosmological parameters. In particular, a wrong or inaccurate calibration might mimic the presence of a gravitational wave background, or a signal from cosmological birefringence, a phenomenon characteristic of several non-standard, symmetry breaking theories of electrodynamics that allow for \textit{in vacuo} rotation if the polarization direction of the photon. Noteworthly, several authors have claimed that the BOOMERanG 2003 (B2K) published polarized power spectra of the CMB may hint at cosmological birefringence. Such analyses, however, do not take into account the reported calibration uncertainties of the BOOMERanG focal plane. We develop a formalism to include this effect and apply it to the BOOMERanG dataset, finding a cosmological rotation angle $\alpha=-4.3^\circ\pm4.1^\circ$. We also investigate the expected performances of future space borne experiment, finding that an overall miscalibration larger then $1^\circ$ for Planck and $0.2\circ$ for EPIC, if not properly taken into account, will produce a bias on the constraints on the cosmological parameters and could misleadingly suggest the presence of a GW background.Comment: 10 pages, 3 figure

Traffic control via moving bottleneck of coordinated vehicles

International audienceThe possibility of properly controlling a moving bottleneck to improve the traffic flow is here considered. The traffic is represented by means of a macroscopic model able to take into account the interactions with the bottleneck. This latter interacts with the surrounding flow modifying the traffic density and the flow speed profiles. An optimal control problem is stated by using the speed of the moving bottleneck as control variable. Specifically in this paper the MPC (Model Predictive Control) approach is used in order to get a fuel consumption reduction when the traffic is congested due to the presence of a fixed bottleneck on the highway. In addition we have demonstrated that no increase of the travel time is caused by the control application. The concept illustrated in this paper suggests a future innovative traffic control approach. Indeed the prospective of exploiting special vehicles with manipulable speed to control the traffic flow is particularly attractive given the expected increasing penetration rate of autonomous vehicles in traffic networks in future years

Exploring the geomorphological adequacy of the landslide susceptibility maps: A test for different types of landslides in the Bidente river basin (northern Italy)

Landslide susceptibility modelling is a crucial tool for implementing effective strategies in landslide risk mitigation. A plethora of statistical methods is available for generating accurate prediction images; however, the reliability of these models in terms of geomorphological adequacy is often overlooked by scholars. This critical flaw may result in concealed prediction errors, undermining the trustworthiness of the obtained maps. A key aspect of evaluating the geomorphological soundness of these models lies in factor analysis, specifically considering the correlation of explanatory variables with the final susceptibility score rather than solely focusing on their impact on model accuracy. This study delves into research conducted in the Bidente river basin (Italy) that analyes results obtained from slide, flow, and complex susceptibility models using Weight of Evidence (WoE) and Multivariate Adaptive Regression Splines (MARS) statistical methods. The research critically examines each factor class's role in defining susceptibility scores for different landslide typologies. The comparison between susceptibility maps generated by WoE and MARS for each typology (slide = 0.78; flow = 0.85; complex: 0.79) (slide = 0.78; flow = 0.85; complex: 0.79)reveals good to excellent prediction skill, with MARS demonstrating a 5 % higher performance index. The study emphasises the importance of spatial relationships between variables and landslide occurrences, highlighting that individual classes of variables influence the final susceptibility score based on their combined role with other predictor classes. In particular, in this study, results highlight that lithotecnical and landform classification classes delimit the landslide domain, while topographic attributes (steepness, curvatures, SPI and TWI) modulate the score inside. The proposed approach offers insights into investigating the geomorphological adequacy of landslide prediction images, emphasising the significance of factor analysis in evaluating model reliability and uncovering potential errors in susceptibility maps

Traffic Control via Platoons of Intelligent Vehicles for Saving Fuel Consumption in Freeway Systems

International audienceIn this paper a coupled PDE-ODE model describing the interaction between the bulk traffic flow and a platoon of connected vehicles is adopted to develop a control action aiming at reducing the fuel consumption of the overall traffic flow. The platoon is modeled as a capacity restriction acting on the surrounding traffic. The trajectory of the initial and final points of the platoon are optimized by means of a model predictive control strategy, acting on the speeds of the front-end and back-end of the platoon, thus resulting in controlling both the speed and the length of the platoon. The approach is assessed in simulations

Bone Marrow Foot Oedema in Adolescents: The Role of Vitamin D

BACKGROUND: Bone marrow oedema (BMO) in children/adolescents is a rare clinical condition without an etiologic cause. It is associated with typical increased signal intensity on T2-weighted magnetic resonance images (MRI) and an increase in bone turnover in which vitamin D plays a pivotal role. No treatment guidelines for these young patients are to date available. METHODS: We performed a retrospective study in a pediatric setting of 13 patients with diagnosis of primary BMO of the foot on the basis of clinical and radiological findings. Data collection included sex, age, patient history, symptoms at presentation, clinical examination, laboratory bone turnover markers, vitamin D levels, MRI, treatment, and outcome. RESULTS: Vitamin D deficiency or insufficiency was found in 76.9% of cases. All patients were treated with adequate vitamin D daily intake, a short course of analgesic therapy, physical therapy, avoiding detrimental feet and ankle immobilization. All fully recovered in 3-month lag period. CONCLUSIONS: Our data highlight that environmental factors, such as underestimated articular or bone microtraumatisms, as well as joint hyper mobility, in a bone turnover milieu of vitamin D deficiency could be the cause of this clinical conditions. Adequate vitamin D supplementation, associated with physical and analgesic therapy, is crucial in the management of BMO