Search results for " Opera"
showing 10 items of 3606 documents
An optimality test for semi-infinite linear programming
1992
In this paper we present a test to characterize the optimal solutions for the continuous semi-infinite linear programming problem. This optimality characterization is a condition of Kuhn–Tucker type. The resolution of a linear program permits to check the optimality of a feasible point,to detect the unboundedness of the problem and to find descent directions. We give some illustrative examples. We show that the local Mangasarian–Fromovitz constraint qualification is almost equivalent to Slater qualification for this problem. Furthermore, it follows from our study that this optimality condition is always necessary for a wide class of semi-infinite linear programming problems
Optimal switches in multi-inventory systems
2007
Given a switched multi-inventory system we wish to find the optimal schedule of the resets to maintain the system in a safe operating interval, while minimizing a function related to the cost of the resets. We discuss a family of instances that can be solved in polynomial time by linear programming. We do this by introducing a set-covering formulation with a totally unimodular constraint matrix.
Improving data quality in construction engineering projects : an action design research approach
2014
Aurthor's version of an article in the journal: Journal of Management in Engineering. Also available from the publisher at: http://dx.doi.org/10.1061/(ASCE)ME.1943-5479.0000202 The topic of data and information quality (DQ/IQ) is a longstanding issue of interest in both academia and practice in the construction engineering field. Poor DQ/IQ has led to poor engineering drawings that, in turn, have led to delays and, eventually, cost overruns. In this paper, a study is reported that took an action design research (ADR) approach to develop and evaluate a DQ/IQ assessment tool, which is called the information quality system (IQS), in a large global engineering and construction company. The eval…
Assessing eco-efficiency with directional distance functions
2012
Abstract Eco-efficiency is a matter of concern at present that is receiving increasing attention in political, academic and business circles. Broadly speaking, this concept refers to the ability to create more goods and services with less impact on the environment and less consumption of natural resources, thus involving both economic and also ecological issues. In this paper we propose the use of directional distance functions and Data Envelopment Analysis techniques to assess eco-efficiency. More specifically, we show how these functions can be used to compute a wide range of indicators representing different objectives regarding economic and ecological performance. This methodological ap…
HUMAN RESOURCES MANAGEMENT IN MARITIME CONTAINER TERMINALS: OPTIMISATION METHODS AND POLICY IMPLICATIONS
2014
In the competitive environment of container transport, Container Terminals (CT) have to plan carefully the management of their resources and services in order to satisfy shipping companies’ requirements. Failure to do so may lead vessel operators to re-schedule their routes calling at new promising terminals. In particular, the optimal management of human resources is a major issue in port systems having low automation and high labour costs. This thesis aims at providing a large overview of current practices and issues concerning the management of dockworkers in the CT area, in order to suggest the analytical methods and policies for its improvement. The focus is on the operational plan (24…
Orbits of bounded bijective operators and Gabor frames
2020
This paper is a contribution to frame theory. Frames in a Hilbert space are generalizations of orthonormal bases. In particular, Gabor frames of $L^2(\mathbb{R})$, which are made of translations and modulations of one or more windows, are often used in applications. More precisely, the paper deals with a question posed in the last years by Christensen and Hasannasab about the existence of overcomplete Gabor frames, with some ordering over $\mathbb{Z}$, which are orbits of bounded operators on $L^2(\mathbb{R})$. Two classes of overcomplete Gabor frames which cannot be ordered over $\mathbb{Z}$ and represented by orbits of operators in $GL(L^2(\mathbb{R}))$ are given. Some results about opera…
Preliminary CAD implementation of EU-DEMO primary heat transfer systems for HCPB breeding blanket option
2019
Abstract This paper focuses on the 3D CAD implementation of the pipework and the main equipment of the Primary Heat Transfer System of EU-DEMO fusion power plant. In particular, the systems related to the Helium-Cooled Pebble Bed Breeding Blanket option are considered here. During the pulse operation, the breeding blanket modules will be the main thermal power source; Divertor and the Vacuum Vessel will contribute in the definition of the total reactor power. All the In-Vessel generated power is rejected to the Power Conversion System through a molten salt Intermediate Heat Transport System. The latter is equipped with an Energy Storage System to allow for continuous operation also during t…
An evolutionary method for complex-process optimization
2010
10 páginas, 7 figuras, 7 tablas
Black box scatter search for general classes of binary optimization problems
2010
The purpose of this paper is to apply the scatter search methodology to general classes of binary problems. We focus on optimization problems for which the solutions are represented as binary vectors and that may or may not include constraints. Binary problems arise in a variety of settings, including engineering design and statistical mechanics (e.g., the spin glass problem). A distinction is made between two sets of general constraint types that are handled directly by the solver and other constraints that are addressed via penalty functions. In both cases, however, the heuristic treats the objective function evaluation as a black box. We perform computational experiments with four well-k…
Una postilla su una delle novità introdotte dall’art. 84 del codice dei contratti pubblici (d.lgs. n. 50/2016). L’obbligo delle stazioni appaltanti d…
2016
A NOTE ON ONE OF THE NEW MEASURES INTRODUCED BY ARTICLE 84 OF THE ITALIAN PUBLIC PROCUREMENTS CODE (LEGISLATIVE DECREE NO 50/2016). THE OBLIGATION OF CONTRACTING AUTHORITIES TO VERIFY THE QUALIFICATION CERTIFICATE OF CONTRACTORS ISSUED BY SOA Article 84 of the new Italian Public Procurements Code, which (along with other provisions) sets out the qualification system for economic operators offering the execution of works for an amount equal to or over 150,000 Euro, introduces several new provisions. In addition to the widely publicised and certainly significant one attributing broad regulatory powers to ANAC (the Italian Independent Authority supervising public procurements), Article 84 impo…