Institution
University of Siena
Education•Siena, Italy•
About: University of Siena is a education organization based out in Siena, Italy. It is known for research contribution in the topics: Population & Cancer. The organization has 12179 authors who have published 33334 publications receiving 1008287 citations. The organization is also known as: Università degli studi di Siena & Universita degli studi di Siena.
Topics: Population, Cancer, Large Hadron Collider, Sperm, Oxidative stress
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TL;DR: A priori sufficient conditions for Lyapunov asymptotic stability and exponential stability are derived in the terminal cost and constraint set fashion, while allowing for discontinuous system dynamics and discontinuous MPC value functions.
Abstract: In this note, we investigate the stability of hybrid systems in closed-loop with model predictive controllers (MPC). A priori sufficient conditions for Lyapunov asymptotic stability and exponential stability are derived in the terminal cost and constraint set fashion, while allowing for discontinuous system dynamics and discontinuous MPC value functions. For constrained piecewise affine (PWA) systems as prediction models, we present novel techniques for computing a terminal cost and a terminal constraint set that satisfy the developed stabilization conditions. For quadratic MPC costs, these conditions translate into a linear matrix inequality while, for MPC costs based on 1, infin-norms, they are obtained as norm inequalities. New ways for calculating low complexity piecewise polyhedral positively invariant sets for PWA systems are also presented. An example illustrates the developed theory
233 citations
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University of Manchester1, Free University of Berlin2, Royal National Hospital for Rheumatic Diseases3, Southampton General Hospital4, Katholieke Universiteit Leuven5, Northern General Hospital6, Charles University in Prague7, Ruhr University Bochum8, Lund University9, University of Sheffield10, National and Kapodistrian University of Athens11, New York Academy of Medicine12, University of Siena13, Erasmus University Rotterdam14, University of Aberdeen15, Humboldt University of Berlin16, University of Göttingen17, Royal Cornwall Hospital18
TL;DR: The data suggest that modification of other lifestyle risk factors is unlikely to have a major impact on the population occurrence of vertebral fractures, and the important biological mechanisms underlying vertebral fracture risk need to be explored using new investigational strategies.
Abstract: The aim of this analysis was to determine the influence of lifestyle, anthropometric and reproductive factors on the subsequent risk of incident vertebral fracture in men and women aged 50-79 years. Subjects were recruited from population registers from 28 centers across Europe. At baseline, they completed an interviewer-administered questionnaire and had lateral thoraco-lumbar spine radiographs performed. Repeat spinal radiographs were performed a mean of 3.8 years later. Incident vertebral fractures were defined morphometrically and also qualitatively by an experienced radiologist. Poisson regression was used to determine the influence of the baseline risk factor variables on the occurrence of incident vertebral fracture. A total of 3173 men (mean age 63.1 years) and 3402 women (mean age 62.2 years) contributed data to the analysis. In total there were 193 incident morphometric and 224 qualitative fractures. In women, an age at menarche 16 years or older was associated with an increased risk of vertebral fracture (RR = 1.80; 95%CI 1.24, 2.63), whilst use of hormonal replacement was protective (RR = 0.58; 95%CI 0.34, 0.99). None of the lifestyle factors studied including smoking, alcohol intake, physical activity or milk consumption showed any consistent associations with incident vertebral fracture. In men and women, increasing body weight and body mass index were associated with a reduced risk of vertebral fracture though, apart from body mass index in men, the confidence intervals embraced unity. For most variables the strengths of the associations observed were similar using the qualitative and morphometric approaches to fracture definition. In conclusion our data suggest that modification of other lifestyle risk factors is unlikely to have a major impact on the population occurrence of vertebral fractures. The important biological mechanisms underlying vertebral fracture risk need to be explored using new investigational strategies.
233 citations
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TL;DR: In this paper, the authors studied the problem of containment of symbolic powers in a polynomial ring over an algebraically closed field, and showed that the containment theorems of Ein-Lazarsfeld-Smith and Hochster-Huneke are optimal for every fixed dimension and codimension.
Abstract: We develop tools to study the problem of containment of symbolic powers $I^{(m)}$ in powers $I^r$ for a homogeneous ideal $I$ in a polynomial ring $k[{\bf P}^N]$ in $N+1$ variables over an algebraically closed field $k$. We obtain results on the structure of the set of pairs $(r,m)$ such that $I^{(m)}\subseteq I^r$. As corollaries, we show that $I^2$ contains $I^{(3)}$ whenever $S$ is a finite generic set of points in ${\bf P}^2$ (thereby giving a partial answer to a question of Huneke), and we show that the containment theorems of Ein-Lazarsfeld-Smith and Hochster-Huneke are optimal for every fixed dimension and codimension.
233 citations
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TL;DR: The findings lend support to the hyperosmolarity hypothesis of exercise-induced asthma and may have therapeutic implications.
233 citations
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TL;DR: The implementation of a real-time traffic management system, called ROMA (Railway traffic Optimization by Means of Alternative graphs), to support controllers in the everyday task of managing disturbances, making use of a branch-and-bound algorithm for sequencing train movements, while a local search algorithm is developed for rerouting optimization purposes.
Abstract: Traffic controllers regulate railway traffic by sequencing train movements and setting routes with the aim of ensuring smooth train behaviour and limiting, as much as possible, train delays. In this paper, we describe the implementation of a real-time traffic management system, called ROMA (Railway traffic Optimization by Means of Alternative graphs), to support controllers in the everyday task of managing disturbances. We make use of a branch-and-bound algorithm for sequencing train movements, while a local search algorithm is developed for rerouting optimization purposes. The compound problem of routing and sequencing trains is approached iteratively, computing an optimal train sequencing for given train routes and then improving this solution by locally rerouting some trains. An extensive computational study is carried out, based on a dispatching area of the Dutch railway network. We study practical size instances, and include in the model important operational constraints, including rolling stock and passenger connections. Different types of disturbances are analysed, including train delays and blocked tracks. Comparison with common dispatching practice shows the high potential of the system as an effective support tool to improve punctuality.
233 citations
Authors
Showing all 12352 results
Name | H-index | Papers | Citations |
---|---|---|---|
Johan Auwerx | 158 | 653 | 95779 |
I. V. Gorelov | 139 | 1916 | 103133 |
Roberto Tenchini | 133 | 1390 | 94541 |
Francesco Fabozzi | 133 | 1561 | 93364 |
M. Davier | 132 | 1449 | 107642 |
Roberto Dell'Orso | 132 | 1412 | 92792 |
Rino Rappuoli | 132 | 816 | 64660 |
Teimuraz Lomtadze | 129 | 893 | 80314 |
Manas Maity | 129 | 1309 | 87465 |
Dezso Horvath | 128 | 1283 | 88111 |
Paolo Azzurri | 126 | 1058 | 81651 |
Vincenzo Di Marzo | 126 | 659 | 60240 |
Igor Katkov | 125 | 972 | 71845 |
Ying Lu | 123 | 708 | 62645 |
Thomas Schwarz | 123 | 701 | 54560 |