1,720,989 research outputs found
Optimal decentralized routing policies for a class of queueing networks
No full textThe authors deal with optimal control problems of deterministic queuing networks. The class of networks considered is characterized by a single-class population of customers, each of which has to undergo the same sequence of operations. The network is composed of a number of identically structured islands, where a decisional node has to route incoming customers to one between two different servers. With reference to the minimization of the mean flow time in the overall network, the optimality of an informationally decentralized, threshold-type, and quasi-stationary policy is proved
Optimal routing of customers with general independent interarrival times in simple deterministic networks
No full textThreshold policies minimizing customer mean flow time in simple (out-tree) queueing networks
No full textClosed loop steering of unicycle like vehicles via Lyapunov techniques
No full textWith a special choice for the system state equations, the use of the simplest quadratic form as candidate Lyapunov function directly leads to the definition of very simple, smooth and effective closed loop control laws for unicycle-like vehicles, suitable to be used for steering, path following, and navigation. The authors provide simulation examples to show the effectiveness and, in a sense, the “natural behavior” of the obtained closed loop motions (when compared with everyday driving experience
Modelling and optimization of emissions in steady state urban traffic networks
No full textNowadays, to manage the increasing traffic demands, it is necessary to define methods and tools to manage traffic flows, taking into account dynamic models over a network and network-wide emissions. The paper presents an optimization model to minimize emissions in urban traffic networks in steady-state conditions. First of all, the equilibrium point assessment is carried out in the presence of constant splitting rates for each node, proving the asymptotical stability of the unique equilibrium point thanks to the direct Lyapunov method. Then, an optimization problem for minimizing emissions in steady-state is formulated and discussed, including the stability conditions. The proposed approach has been tested over a 9 nodes-12 arcs test network, showing emissions reduction in contrast to a non-optimized scenario
Definitive breast cancer surgery as an outpatient: rationale and our experience
No full textThe objective of this study was to evaluate the feasibility of outpatient breast definitive surgery. CASE and METHODS: Between January 2001 and September 2003 181 definitive breast cancer surgical approaches were performed at Surgical Department of Genoa University on 173 patients. Mean age was 60 years (28-92). All the patients were discharged the day of surgery or the day after in the morning. RESULTS: There were no major complications or deaths. The specific complication rate was similar to inpatient setting and there was no readmission. The patients' quality of life and satisfaction were satisfactory or good. DISCUSSION: In conclusion, holding in due consideration some philosophical and technical changes, breast cancer surgery can be safely and comfortably performed on an outpatient basis
LA CHIRURGIA MAGGIORE DELLA MAMMELLA IN DAY-SURGERY: RAZIONALE E NOSTRA ESPERIENZA
No full textINTRODUCTION: The objective of this study was to evaluate the feasibility of outpatient breast definitive surgery. CASE and
METHODS: Between January 2001 and September 2003 181 definitive breast cancer surgical approaches were performed at Surgical Department of Genoa University on 173 patients. Mean age was 60 years (28-92). All the patients were discharged the day of surgery or the day after in the morning.
RESULTS: There were no major complications or deaths. The specific complication rate was similar to inpatient setting and there was no readmission. The patients' quality of life and satisfaction were satisfactory or good.
DISCUSSION: In conclusion, holding in due consideration some philosophical and technical changes, breast cancer surgery can be safely and comfortably performed on an outpatient basis
Stochastic Traffic assignment with Electric Vehicles: a convex optimization approach
No full textElectric vehicles and charging stations are increasing worldwide to reduce emissions at the city level. In order to analyze traffic flows and quantify the demand for energy recharge, it is necessary to model users' choices considering different kinds of traffic flows. In this paper, attention is focused on the formalization of the joint traffic and energy demand assignment conditions over a traffic network in presence of electric vehicles (EVs). Specifically, the so-called stochastic user equilibrium (SUE) conditions are used to define the steady state behaviour of a generic traffic network in which some arcs are equipped with EV charging stations. A convex optimization problem is defined and solved, which is equivalent to the solution of the nonlinear and nonconvex set of SUE conditions under a multinomial Logit user's choice function. A real case study, related to a touristic area in the Liguria Region (from Genova airport to Portofino), is considered
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