Search results for "Congestion"
showing 10 items of 79 documents
American Options Based Service Pricing For Virtual Operators
2008
In the recent years, the role of service provider has split into two broad categories: Network Operators, offering services over their networks, and Virtual Operators, providing services over leased resources. What differentiates these players is to a minor extent a matter of enhanced service offer, and primarily a matter of economic objectives and risk attitudes. Essentially, Network Operators own their infrastructures and typically have to sustain both fixed costs (CAPEX) and recurrent costs (OPEX), while Virtual Operators may have a simpler cost structure, mainly consisting of OPEX for hiring the network. Correspondingly, the objectives of these players may differ profoundly: on one hand…
Valutazione degli effetti della legge di riordino del Servizio Sanitario Regionale siciliano su efficienza e appropriatezza delle prestazioni ospedal…
2014
La Legge Regionale n. 5 del 14 aprile 2009 segna un punto di svolta nel processo di riforme che ha interessato il Servizio Sanitario della Regione Siciliana, introducendo, tra l’altro, interventi mirati alla razionalizzazione della rete ospedaliera. Obiettivo del presente lavoro è valutare gli effetti della riforma sulla produzione dei servizi ospedalieri in termini di efficienza e di appropriatezza. L’ipotesi da verificare è se il mutamento del quadro normativo, entro il quale si sono trovati ad operare gli ospedali pubblici e privati accreditati, ha reso possibile il raggiungimento degli obiettivi prestabiliti di efficienza, di riduzione degli sprechi nell’utilizzo delle risorse e miglior…
Air quality model validation in urban area: a new approach using a wireless pervasive sensor system.
2013
This paper describes the implementation in Palermo of a new approach developed at Newcastle University (UK), in the context of the MESSAGE project (Mobile Environmental Sensing System Across Grid Environments), using a novel inexpensive pervasive sensor system. The new system infrastructure shows how additional data from the new environmental sensors, namely “mote” can improve the assessment of the impact of traffic and congestion on air quality. After an evaluation and validation process of the sensors against the precision system (City Council Environmental Cabin) the sensors where deployed in Palermo and using the data, actual traffic flows and pedestrian traffic light information (all s…
The quest for bandwidth estimation techniques for large-scale distributed systems
2010
In recent years the research community has developed many techniques to estimate the end-to-end available bandwidth of an Internet path. This important metric can be potentially exploited to optimize the performance of several distributed systems and, even, to improve the effectiveness of the congestion control mechanism of TCP. Thus, it has been suggested that some existing estimation techniques could be used for this purpose. However, existing tools were not designed for large-scale deployments and were mostly validated in controlled settings, considering only one measurement running at a time. In this paper, we argue that current tools, while offering good estimates when used alone, migh…
A genetic algorithm for the design of a fuzzy controller for active queue management
2003
Active queue management (AQM) policies are those\ud policies of router queue management that allow for the detection of network congestion, the notification of such occurrences to the\ud hosts on the network borders, and the adoption of a suitable control\ud policy. This paper proposes the adoption of a fuzzy proportional\ud integral (FPI) controller as an active queue manager for Internet\ud routers. The analytical design of the proposed FPI controller is\ud carried out in analogy with a proportional integral (PI) controller,\ud which recently has been proposed for AQM. A genetic algorithm is\ud proposed for tuning of the FPI controller parameters with respect\ud to optimal disturbance rej…
Assessing the effect of transmission constraints on wind power expansion in northeast Brazil
2019
Abstract The rapid growth of the wind industry in Brazil presents new opportunities and challenges for its electricity industry. As new capacity becomes available, more transmission infrastructure is required for security of supply. The Brazilian electricity system has experienced congestion in the northeast region, affecting the coordinated expansion of transmission and new wind power capacity. This paper uses a simulation model for better assessing long-term policy synchrony of the wind industry. The simulation shows that the resulting prices are competitive in the middle to long terms.
A Fuzzy Approach for the Network Congestion Problem
2002
Urban Traffic Analysis through an UAV
2014
Abstract In order to realize a precise and accurate traffic study, a method to evaluate the real traffic flow conditions in urban areas based on videos acquired by an UAV, Unmanned Aerial Vehicle, is proposed. In this way it does not require additional equipment to earth and, not being invasive, does not influence the driver behavior. This paper presents the results obtained in terms of vehicular traffic flow along a way in the city of Palermo. The results have been compared to experiments using macroscopic simulation models and the eventually differences have been discussed.
TWO-LANE TRAFFIC WITH PLACES OF OBSTRUCTION TO TRAFFIC
2004
As the Nagel–Schreckenberg model (NaSch model) became known as a realistic approach to describe traffic flow on single-lane streets, this model was extended to two-lane traffic by several groups. On the base of our two-lane model, we will now investigate the impact of a place of obstruction, e.g., because of road works, on partial fractions, densities and mean velocities.
Motivational and Emotional Aspects Involved in Driving
2001
It is evident that individuals display different behaviors when driving and especially when involved in accidents. These differences seem to be related in various ways to physical, mental and socio-environmental characteristics of the driver. It is also known that a wide range of situational variables that are all too common in our daily lives, such as fatigue, use of drugs, alcohol or certain medication; sleepiness and transitory behavioral alterations such as stress or anxiety, have a negative influence on driving.