454 research outputs found
System parameter, lot-size, and work-in-progress optimization in manufacturing processes : an approach based on the application of Timed Event Graphs
No full textOpen Problems in Transportation Engineering with Connected and Autonomous Vehicles
No full textAbstractIn recent decades, technologies that can lead to fully automated driving have had a rapid development. In this framework, ‘road transport automation’ can potentially result in significant changes to the operation of road systems throughout the world. It is impossible to foresee how long it will take to realize such potential changes, because there are many uncertainties about both the technologies to deploy, and the policy environment where they should be deployed. ‘Full automation’ is the future of road transport, but the transition from manual to fully autonomous vehicles is especially dependent on the interactions between humans and automation, but also between automated vehicles and manual vehicles, and between automated vehicles and infrastructure.In the above context, this paper, after introducing some open problems related to automated vehicles, focuses on a particular one, consisting of the simplified evaluation of the equilibrium points achievable by a mixed flow with different percentages of automated vehicles. The aim of the considered problem is to provide a first general estimation of the performance of an existing network in various scenarios, characterized by different percentages of autonomous vehicles and mobility demand. More in detail, a simplified kinematic supply model is introduced to assess the link flow/cost performances, aiming at estimating the potential congestion reduction. An application to a real word network is described, and the relevant results are reported and discussed
Neural approximations for feedback optimal control of freeway systems
No full textThe problem of clearing congestion situations in freeway traffic is addressed for both an N-stage and an infinite-stage control horizon (in the latter case, a receding-horizon control mechanism is used). Traffic is controlled by regulating the vehicle access to the freeway and by limiting the vehicle speed by means of variable message signs. To describe the traffic behavior, a "classical" macroscopic model, first proposed by Payne, is adopted. Even though the problem is stated within a deterministic context, an optimal control law in feedback form is sought to react to unpredictable events. The resulting functional optimization problem is reduced to a nonlinear programming problem by constraining the control law to take on a fixed structure in which free parameters have to be optimized. For such a structure, a multilayer feedforward neural mapping is chosen. Simulation results show the effectiveness of the proposed method in two different case studies. For the simulation of the second case study, real traffic data are used, which allows one to very well represent critical traffic conditions on freeways
A Petri-net based approach for the interdependence analysis of critical infrastructures in transportation networks
No full textThe paper deals with the problem of estimating the indirect consequences of safety and security accidents in the so-called transportation Critical Infrastructures, i.e., those assets consisting of systems, resources, and/or processes whose total or partial destruction, or even temporary unavailability, has the effect of damaging or significantly weakening the efficiency and the normal functioning of a Country.
In this framework, the aim of this paper is to define a methodology for estimating the costs deriving from the “chain-effect” which characterizes many CIs, in terms of reachability/non-reachability of some network nodes.
In doing so, a modelling approach based on Petri Nets (PNs) is proposed, being them a suitable formalism to predict the behaviour of a whole transportation network as a consequence of particular events occurring in it.
In the paper, after introducing and describing the PN models of transportation CIs, a case study is presented and discussed
Eribulin Treatment in Patients with Liver Metastatic Breast Cancer: Eight Italian Case Reports
No full textLiver metastases are very common in metastatic breast cancer (MBC); current treatments for these lesions are based on systemic chemotherapy, endocrine- or human epidermal growth factor receptor 2 (HER2)-targeted therapy, and palliative therapy. However, no standard approach has been clearly identified for second and further chemotherapy lines in MBC patients. In the phase III clinical trial EMBRACE, eribulin was particularly effective in reducing liver lesions and improving both overall survival and progression-free survival in liver MBC patients. In this series, we collected 8 case reports of Italian clinical practice in which eribulin has shown significant efficacy in reducing liver metastases in MBC patients: complete response was reported in 2 patients, and 4 patients achieved partial response. The treatment was well tolerated, thus confirming that eribulin is a suitable therapeutic option for elderly patients and for those who have metastatic HER2-negative disease. In the setting of MBC, the sequencing of therapeutic agents should consider expected response, side effects, tumor characteristics, and patient's preferences, in order to successfully tailor the most appropriate therapy beyond earlier lines
Modelling and simulating for optimal management of underground railway systems
No full textthe problem of determining a suitable schedule for the train traffic on an underground railway network is faced in this paper. In particular lines made up of track circuits (TCs) are considered. A `tentative' schedules is obtained by the solution of a mathematical optimization problem, which consider a simple model. Then, a deterministic event-driven simulator receives the tentative schedule as input in order to test it on a more complete model. From this latter phase some feedback may be sent to the optimization module, so as to perform an adaptive procedure to find a schedule which satisfies both the system dynamic and safety constraints imposed by the presence of the TCs. The obtained solution is found neglecting the stochastic characteristics of the system
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