Search results for "vento"

Boolean-controlled systems via receding horizon and linear programing

2009

We consider dynamic systems controlled by boolean signals or decisions. We show that in a number of cases, the receding horizon formulation of the control problem can be solved via linear programing by relaxing the binary constraints on the control. The idea behind our approach is conceptually easy: a feasible control can be forced by imposing that the boolean signal is set to one at least one time over the horizon. We translate this idea into constraints on the controls and analyze the polyhedron of all feasible controls. We specialize the approach to the stabilizability of switched and impulsively controlled systems.

Robust optimality of linear saturated control in uncertain linear network flows

2008

We propose a novel approach that, given a linear saturated feedback control policy, asks for the objective function that makes robust optimal such a policy. The approach is specialized to a linear network flow system with unknown but bounded demand and politopic bounds on controlled flows. All results are derived via the Hamilton-Jacobi-Isaacs and viscosity theory.

ROBUST CONTROL STRATEGIES FOR MULTI—INVENTORY SYSTEMS WITH AVERAGE FLOW CONSTRAINTS

2006

Abstract In this paper we consider multi—inventory systems in presence of uncertain demand. We assume that i) demand is unknown but bounded in an assigned compact set and ii) the control inputs (controlled flows) are subject to assigned constraints. Given a long—term average demand, we select a nominal flow that feeds such a demand. In this context, we are interested in a control strategy that meets at each time all possible current demands and achieves the nominal flow in the average. We provide necessary and sufficient conditions for such a strategy to exist and we characterize the set of achievable flows. Such conditions are based on linear programming and thus they are constructive. In …

Improvement of Inventory Control under Parametric Uncertainty and Constraints

2011

The aim of the present paper is to show how the statistical inference equivalence principle (SIEP), the idea of which belongs to the authors, may be employed in the particular case of finding the effective statistical decisions for the multi-product inventory problems with constraints. To our knowledge, no analytical or efficient numerical method for finding the optimal policies under parametric uncertainty for the multi-product inventory problems with constraints has been reported in the literature. Using the (equivalent) predictive distributions, this paper represents an extension of analytical results obtained for unconstrained optimization under parametric uncertainty to the case of con…

Inventory policies and information sharing in multi-echelon supply chains

2011

The aim of this article is to show how to modify a replenishment rule in relation to the operational information shared by suppliers. More specifically, we present a model of an Automatic Pipeline Variable Inventory and Order-Based Production Control System rule for a multi-echelon supply chain characterised by different increasing levels of shared information. A numerical study is presented to underline the performance differences for three variants of the smoothing order rule in terms of bullwhip reduction, inventory stability and operational and customer responsiveness. Results show how the effectiveness of a smoothing replenishment rule depends on the level of information sharing.

Production Inventory and Enterprise System Implementation: An Ex-ante No-Cost Based Evaluation

2010

The objective of this paper is to present an Enterprise System (ES) ex-ante no-cost based three step evaluation technique, which enables a pre-emptive analysis of the effects of an ES implementation using a system of referenced non financial performance metrics. The innovativeness is in the use of a simulation model fully integrated with the evaluation procedure. Researchers can extend the presented technique to further modelling approaches and test it on different market sectors. The analysis provides practitioners with a measurement system that enables an analysis of the effects of a given ES implementation and can be further employed in financial evaluations.

Formulations for an inventory routing problem

2014

In this paper, we present and compare formulations for the inventory routing problem (IRP) where the demand of customers has to be served, over a discrete time horizon, by capacitated vehicles starting and ending their routes at a depot. The objective of the IRP is the minimization of the sum of inventory and transportation costs. The formulations include known and new mathematical programming formulations. Valid inequalities are also presented. The formulations are tested on a large set of benchmark instances. One of the most significant conclusions is that the formulations that use vehicle-indexed variables are superior to the more compact, aggregate formulations.

Possibile origine e consistenza di un popolamento di Quercus trojana Webb subsp. trojana (Fagaceae) nel Bosco della Ficuzza (Palermo, Sicilia

2014

Possible origin and demographic asset of a population of Quercus trojana Webb subsp. trojana (Fagaceae) in the wood of Ficuzza (Palermo, Sicily). The first record of Macedonian oak in Sicily is reported. The finding consists of 73 adult and 4 young individuals. A morphometric analysis of all of them, along with an assessment of their phytosanitary status was carried out. They all grow between 700 and 850 m a.s.l. on a 2,30 ha area, characterized by a land mosaic of shrubland and forest patches. Notwithstanding two years of researches, no ultimate proof has been found on their alien status. On this purpose, several alternative hypothesis are formulated and their strengths and weaknesses are …

Verdadero retrato del Santísimo Christo del Paño, venerado en el Convento de la Merced de Cadiz

La p. [1] és el grav. xil. orlat del Vº. R. del Stº. Christo del Paño. La p. [2] és una oració en vers a les tres caigudes de Jesucrist, el primer vers de la qual és: "Fuistes por Judas vendido" El tít. és el text que acompanya al grav. de la p. [1 El grav. xil El text de la oració de la p. [2] a dues col. separades per banda

Verdadero Retrato del Santo Cristo del Paño, venerado en el Convento de la Merced de Cadiz

La p. [1] és el grav. xil. orlat del Vº. R. del Stº. Christo del Paño. La p. [2] és una oració en vers a les tres caigudes de Jesucrist, el primer vers de la qual és: "Fuiste por Judas vendido" El tít. és el text que acompanya al grav. de la p. [1 La p. [1] amb el grav. orlada El grav. xil. "B. T.". Pot ser Baltasar Talamantes? El text de la oració de la p. [2] a dues col. separades per banda