Four-Year Treatment with Octreotide-Long-Acting Repeatable in 110 Acromegalic Patients: Predictive Value of Short-Term Results?

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Actors interactions and needs in the European electromobility network

The standardization of services in the European electromobility network is becoming one of the main goal of researchers and practitioners. In this context, the objective of the paper is proposing a general view of the main needs and functions of the involved actors and stakeholders, and to state their interactions within the electromobility network. In particular, actors and stakeholders are grouped in so called macro-areas, and the interoperability and cooperation at both macro-areas and actors levels are provided by means of Unified Modeling Language (UML) diagrams

Distributed Discrete Consensus Algorithms: Theory and Applications for the Task Assignment Problem

2013/2014Distributed computation paradigms belong to a research field of increasing interest. Using these algorithms will allow to exploit the capabilities of large scale networks and systems in the near future. Relevant information for the resolution of a problem are distributed among a network of agents with limited memory and computation capability; the problem is solved only by means of local computation and message exchange between neighbour agents. In this thesis we consider the multi-agent assignment problem dealt with distributed computation: a network of agents has to cooperatively negotiate the assignment of a number of tasks by applying a distributed discrete consensus algorithm which defines how the agents exchange information. Consensus algorithms are dealt with always more frequently in the related scientific literature. Therefore, in the first chapter of this thesis we present a related literature review containing some of the most interesting works concerning distributed computation and, in particular, distributed consensus algorithms: some of these works deal with the theory of consensus algorithms, in particular convergence properties, others deal with applications of these algorithms. In the second chapter the main contribution of this thesis is presented: aniterative distributed discrete consensus algorithm based on the resolution of local linear integer optimization problems (L-ILPs) to be used for the multi-agent assignment problem. The algorithm is characterized by theorems proving convergence to a final solution and the value of the convergence time expressed in terms of number of iterations. The chapter is concluded by a performance analysis by means of the results of simulations performed with Matlab software. All the results are presented considering two different network topologies in order to model two different real life scenarios for the connection among agents. The third chapter presents an interesting application of the proposed algorithm: a network of charging stations (considered as agents) has to reach a consensus on the assignment of a number of Electric Vehicles (EVs) requiring to be recharged. In this application the algorithm proposed in the previous chapter undergoes several modifications in order to model effectively this case: considering the inter-arrival times of vehicles to a charging station, a non-linear element appears in the objective function and therefore a novel algorithm to be performed before the assignment algorithm is presented; this algorithm defines the order in which the assigned vehicles have to reach a charging station. Moreover, a communication protocol is proposed by which charging stations and vehicles can communicate and exchange information also allowing charging stations to send to each assigned vehicle the maximum waiting time which can pass before a vehicle loses its right to be recharged. The chapter ends with an example of application of the rivisited assignment algorithm. In the fourth and last chapter, we present an application in an industrial environment: a network of Autonomous Guided Vehicles (AGVs) in a warehouse modeled as a graph has to perform the distributed discrete consensus algorithm in order to assign themselves a set of destinations in which some tasks are located. This application deals not only with the task assignment problem but also with the following destination reaching problem: therefore a distributed coordination algorithm is proposed which allows the AGVs to move into the warehouse avoiding collisions and deadlock. An example of the control strategy application involving both the assignment and coordination algorithms concludes this chapter.XXVII Ciclo198

A framework for the distributed management of charging operations

This paper proposes a solution for the distributed dynamic assignment of a set of electric vehicles to a network of charging stations. Drivers of the electric vehicles and charging stations exchange messages using a communication protocol. Drivers of the vehicles send requests for the charging of their own vehicle in prefixed timeslots; charging stations perform a series of distributed optimizations in order to reach a common assignment of the vehicles needing to recharge and communicate the reached assignment to the drivers. The optimization problem is solved using some distributed multi-agent assignment algorithms: the stations reach a consensus solving some local integer linear programming problems. \ua9 2014 IEEE

Decentralized deadlock-free control for AGV systems

This paper proposes a decentralized control strategy to assign tasks to Autonomous Guided Vehicles (AGV) and coordinate their paths to avoid deadlock and collisions. We consider a zone-controlled guidepath network where a set of intelligent vehicles (agents) has to autonomously reach a consensus about the distribution of a set of tasks, i.e., a set of zones to be reached. To this aim the agents apply a discrete consensus algorithm in order to locally minimize the global cost for reaching the destination zone. Moreover, we present a decentralized coordination protocol that is based on a zone-controlled approach with the aim of avoiding deadlock and collisions. \ua9 2015 American Automatic Control Council

Fleet sizing for electric car sharing system via closed queueing networks

This paper addresses the problem of determining the optimal fleet size of electric car sharing systems. We model the system as a Discrete Event System in a closed queueing network framework considering the specific requirements of the electric vehicle utilization. Hence, we describe the asymptotic behavior of the vehicles and develop an optimization problem for maximizing the system revenue by determining the optimal fleet size. The large-scale of real-world systems results in computational difficulties in obtaining the exact solution, and so an approximate formulation is provided. Some numerical results illustrate and validate the solution method. \ua9 2014 IEEE

Simulation Study on the Convergence Time of a Discrete Consensus Algorithm for Distributed Task Assignment

This paper presents results on the convergence time of a previously proposed algorithm to solve the distributed task assignment problem on a network of agents. The considered algorithm consists in iterative local integer linear optimizations among the agents to cooperatively assign a set of tasks. Local optimizations are performed among a subset of randomly chosen neigh boring agents. This paper discusses a simulation study on the number of iterations and time required by the algorithm to find the best task assignment given the limited information available at each iteration. Simulations on large and small networks with local optimizations that involve a varying number of agents have been performed. \ua9 2015 IEEE

Fault detection and recovery by hybrid Petri nets for automated drug preparation systems

This paper presents an event-based monitor that ensures timely and accurate detection and recovery of system task faults. The monitor model is based on first order hybrid Petri nets, i.e., Petri nets that make use of first order fluid approximation. The proposed fault detection technique relies on a modular framework, so that elementary monitors can be connected with other monitors to check more complex systems while avoiding the state space explosion problem. Moreover, a fault detection and recovery monitor is specified for a system devoted to the automated preparation of pharmaceutical drugs. \ua9 2015, IFAC (International Federation of Automatic Control) Hosting by Elsevier Ltd. All rights reserved