Short-term traffic predictions on large urban traffic networks: applications of network-based machine learning models and dynamic traffic assignment models

The paper discusses the issues to face in applications of short-term traffic predictions on urban road networks and the opportunities provided by explicit and implicit models. Different specifications of Bayesian Networks and Artificial Neural Networks are applied for prediction of road link speed and are tested on a large floating car data set. Moreover, two traffic assignment models of different complexity are applied on a sub-area of the road network of Rome and validated on the same floating car data set

Metodi e tecnologie per la priorità e la regolarità dei servizi di trasporto collettivo in sede stradale

Questa tesi approfondisce la tematica del miglioramento, in termini di velocità e regolarità, del funzionamento dei sistemi di trasporto collettivo in sede stradale, attraverso strategie di controllo in tempo reale. In particolare in questo lavoro vengono approfondite le strategie di intervento annoverabili nelle due categorie della “Vehicle Priority” e del “Vehicle Holding”, potenzialmente contraddittorie fra loro. L’analisi della letteratura scientifica e delle buone pratiche ha evidenziato come le due strategie di intervento, orientate l’una alla massimizzazione della velocità commerciale e l’altra alla massimizzazione della regolarità di servizio, vengano al momento considerate perlopiù indipendentemente l’una dall’altra, sia nel campo delle applicazioni pratiche che in quello della speculazione teorica. In questo lavoro viene presentato un nuovo approccio unitario che contempera entrambe le strategie di intervento, e viene introdotto un metodo, tradotto in prototipo software, per il calcolo della strategia ottima di regolazione della marcia dei veicoli attraverso punti di controllo fissi (ad es. segnali semaforici stradali) che consenta di perseguire congiuntamente obiettivi di massimizzazione della velocità e della regolarità di servizio. Il metodo di ottimizzazione qui formulato e testato si basa sull’uso combinato di (meta)euristiche (di tipo Genetico, PSO ed Hill Climbing) e metodi di simulazione del traffico capaci di riprodurre e prevedere le traiettorie temporali dei singoli veicoli di trasporto collettivo. La capacità di previsione a breve termine insita nell’uso di strumenti simulativi consente di generare soluzioni al problema di regolazione estese “in avanti” sia nello spazio stradale che nel tempo, consentendo quindi un approccio alla regolazione che sia al contempo anticipatorio e non-locale: queste caratteristiche consentono in generale di realizzare riallocazioni nell’uso della capacità tra intersezioni vicine consentendo quindi, ove possibile, di ridurre la competizione tra modi di trasporto diversi nell’uso della capacità stradale. In questo lavoro vengono infine presentati i risultati di una serie di test attuati sia nell’ipotesi di realizzare il controllo attraverso un normale schema semaforico a ciclo e fasi ripetitivi per ciascun segnale, sia nell’ipotesi meno restrittiva di tempi di rosso e di verde in generale variabili per lo stesso segnale. I tempi di calcolo del prototipo realizzato inoltre suggeriscono la possibilità, attraverso ulteriori sviluppi, di utilizzare tale metodo in applicazioni real-time.This thesis explores the theme of improving, in terms of speed and regularity, the road-operation of public transport systems, through control strategies in real time. Specifically in this work are highlighted intervention strategies that falls in the two categories of "Vehicle Priority" and "Vehicle Holding", potentially conflicting the one with the other. The analysis of scientific literature and best practice has shown that the two intervention strategies, leading the first at maximizing the commercial speed and the second to the maximization of regularity of service, are currently considered one independently from the other, both in the field of practical applications than in the one of theoretical speculation. In this work is presented a new unified approach that reconciles both the strategies of intervention; moreover a method is introduced, implemented into a prototype software, for the calculation of the optimal strategy of the vehicle operating through regulation of fixed control points (eg. Signals road traffic lights) to allow a joint pursuit of speed maximization objectives and regularity of service. The optimization method here formulated and tested is based on the combined use of (meta) heuristics (Genetic Algorythm, PSO and Hill Climbing) and traffic simulation methods able to reproduce and predict the temporal trajectories of individual public transport vehicles. The short-term prediction capabilities inherent in the use of simulation tools allows to generate solutions to the regulation problem which are extended "forward" both in the road space and time, thus allowing an approach to regulation that is both anticipatory and non-local. These characteristics allow in general to achieve road capacity relocation between neighboring intersections thus enabling, where possible, to reduce the competition between different modes of transport in the use of road capacity. In this work are finally presented the results of a series of tests carried out both in the case of realizing the control through a normal signal pattern with ripetitive cycle and phases for each signal, both in the hypothesis less restrictive of red and green times generally variables during time for each signal. The calculation effort of the prototype also suggest the possibility, through further developments, to use this method for real-time applications

Drug-coated balloon angioplasty in failing haemodialysis arteriovenous shunts: 12-month outcomes in 200 patients from the Aperto Italian registry

Background: We evaluated the safety and technical and clinical outcomes of angioplasty with a drug-coated balloon for the management of venous stenosis in arteriovenous grafts and arteriovenous fistulas in patients undergoing haemodialysis. Methods: Data were obtained from an ongoing prospective, non-randomised registry conducted at three Italian centres. Patients were treated with a drug-coated balloon according to standard procedures in each participating centre. Evaluation was by colour Doppler imaging every 3 months. The primary end-point was primary assisted patency. The secondary end-point was the rate of assisted patency of the vascular access. Results: A total of 311 angioplasty procedures in 200 patients, (60.4% male), were analysed. The procedural success rate was 100%. A total of 192 treatments of restenosis were necessary in 81 patients during average 21 \ub1 8 months follow-up. Kaplan\u2013Meier estimates indicated that 88.0%, 64.2% and 40.6% of treated lesions were free from restenosis at 6, 12 and 24 months, respectively. Including multiple angioplasty, circuit patency rates were 99.2%, 92.5% and 84.8% at 6, 12 and 24 months, respectively. Primary patency rates were highest in shunts treated de novo with drug-coated balloons. Risk of restenosis was associated with circuit age (p = 0.017), history of treatment with conventional angioplasty (p < 0.001) and the kind of balloon used during pre-dilation (p = 0.001). Conclusion: The results suggest that favourable long-term patency rates can be achieved with the drug-coated balloon in a varied population of patients with failing haemodialysis arteriovenous shunts treated under conditions of actual care

Long-term effects of high-efficiency on-line haemodiafiltration on uraemic toxicity. A multicentre prospective randomized study.

Haemodiafiltration (HDF) may improve survival of chronic dialysis patients. This prospective, multicentre randomized cross-over study evaluated the effects of long-term on-line HDF on the levels of solutes of different molecular weight markers or causative agents of the most common metabolic derangements in uraemia. Methods. Sixty-nine patients from eight Italian centres were randomly assigned to two 6-month treatment sequences: A-B and B-A [A, low-flux haemodialysis (HD) and B, on-line HDF]. Comparative evaluation of basal levels of small, medium-sized and protein-bound solutes at the end of the two treatment periods and analysis of parameters dependence during the interventions were performed. Results. On-line HDF showed greater efficiency than low-flux HD in removing small solutes (eKt/Vurea 1.60 ± 0.31 versus 1.44 ± 0.26, P < 0.0001) and in reducing basal levels of beta2-microglobulin (22.2 ± 7.8 versus 33.5±11.8 mg/L, P < 0.0001), total homocysteine (15.4±5.0 versus 18.7±8.2 μmol/L, P = 0. 003), phosphate (4.6±1.3 versus 5.0±1.4 mg/dL, P = 0.008) and, remarkably, of intact parathyroid hormone (202±154 versus 228±176 pg/mL, P = 0.03). Moreover, in on-line HDF, lower levels of C-reactive protein (5.5±5.5 versus 6.7±6.1 mg/L, P = 0.03) and triglycerides (148±77 versus 167±87 mg/dL, P = 0.008) and increased HDL cholesterol (49.2±12.7 versus 44.7±12.4 mg/dL, P = <0.0001) were observed. The asymmetric dimethylarginine level was not significantly affected (0.97±0.4 versus 0.84±0.37 μmol/L). Erythropoietin and phosphate binders' doses could be reduced. Conclusions. On-line high-efficiency HDF resulted in enhanced removal and lower basal levels of small, medium-sized and protein-bound solutes, which are markers or causative agents of uraemic pathologies, mainly inflammation, secondary hyperparathyroidism and dyslipidaemia. This may contribute to reducing uraemic complications and possibly to improving patient surviva