184 research outputs found
Computational Management Science, special issue
No full textNumero speciale della rivista Computational Management Science. Guest Editors A. Migdalas, P.M. Pardalos, Gerardo Torald
Nonlinear Optimization and Parallel Computing
No full textThe new computational technologies are having a very strong influence on numerical optimization, in several different ways. Many researchers have been stimulated by the need to either conform the existing numerical techniques to the new parallel architectures or to devise completely new parallel solution approaches. A mini-symposium on Parallel Computing in Nonlinear Optimization was held in Naples, Italy, September 2001, during the International Conference ParCo2001, in order to bring together researchers active in this field and to discuss and share their findings. Some of the papers presented during the mini-symposium, as well as additional contributions from other researchers are collected in this special issue. Clearly, two different trends, well representative for most of the current research activities, can be identified. Firstly, there is an attempt to encapsulate parallel linear algebra software and algorithms into optimization codes, particularly codes implementing interior point strategies for which the linear algebra issues are very critical, and secondly, there is an effort to devise new parallel solution strategies in global optimization, either for specific or general purpose problems, motivated by the large size and the combinatorial nature of them. In the present paper we review the literature on these trends and classify the contributed papers within this framework
A Hybrid Genetic—GRASP Algorithm Using Lagrangean Relaxation for the Traveling Salesman Problem
No full textHybridization techniques are very effective for the solution of combinatorial optimization problems. This paper presents a genetic algorithm based on Expanding Neighborhood Search technique (Marinakis, Migdalas, and Pardalos, Computational Optimization and Applications, 2004) for the solution of the traveling salesman problem: The initial population of the algorithm is created not entirely at random but rather using a modified version of the Greedy Randomized Adaptive Search Procedure. Farther more a stopping criterion based on Lagrangean Relaxation is proposed. The combination of these different techniques produces high quality solutions. The proposed algorithm was tested on numerous benchmark problems from TSPLIB with very satisfactory results. Comparisons with the algorithms of the DIMACS Implementation Challenge are also presented</p
Aging in the Contemporary Urban Context: The Mortality Rates of Older Residents in Genoa, Italy
No full textBackground and Aims: The development of contemporary urbanization and the consequent growing complexity of social life have to be related with the demographic ageing process, diffusely interesting more and more Wester as well non-Western societies (Phillipson, 2013). Understanding the lives of the increasing number of older residents within the rapid contextual changing of urban environments become a priority issue both for urban architects and social gerontologists, as well, especially for city decision makers (Scharf et al., 2002; Rodwin et al., 2006; Ogg and Bonvalet, 2007). This study assessed the association between the living conditions of older residents and the urban settings where they experience the ageing process. The main objective was to realize a secondary data analysis leading to an efficient decision support system, focused on a deeply detailed geo-mapping representation of the Genoa municipality (a metropolitan urban context of northern Italy describing an aging index equal to 235.9 in 2013, compared to the national mean value of 152.7 and the EU28 mean value of 117.7), in order to support local policy makers in evaluating the vulnerability risk for older residents and planning adequate urban interventions.
Methods: This was a secondary data analysis combined with a geo-referencing model. The study was realized on big datasets provided by the official statistical registry of the Municipality of Genoa, deepening the analysis to the tiniest possible level of territorial observation. In order to perform a very detailed examination of the contextual living conditions of older residents, we assessed at smallest city block level the association of standard mortality rates of over65s with several factors of social and structural exclusion, like the levels of isolation of older residents, the average income and education levels of the neighborhood, the degree of deterioration of the building environment. Data where analyzed through SPSS statistical software and geospatially represented by QGIS mapping system, providing a detailed map of the whole town describing though adequate alert indicators the different territorial risk for older residents of exposure to vulnerability.
Results: Standard mortality rates of over 65s resulted significantly higher within those city blocks evidencing highest levels of social exclusion, economic deprivation and environmental decay, with a major gender disadvantaged for female older people and for older residents living in suburban contexts. The geo-referenced representation of results provided a mapping alert system helpful for decision makers to plan adequate interventions of social and urban requalification.
Conclusions: Our study, beyond implicit ecological limitations, demonstrates, on the one hand, the importance of focusing a specific attention to inclusion and exclusion processes interesting older people in town environment, and, on the other hand, the opportunity of converting the already available and continuously updated datasets of city registry offices in useful planning tools, helping older residents to better experience later stages of life within the increasing complexity of the contemporary urban setting
Preface
No full textDuring June 15–20, 2014, a group of scientists gathered together in a conferenceon “Optimization, Control and Applications in the Information Age” in order tocelebrate and honor Panos M. Pardalos on the occasion of his 60th birthday. Themeeting took place at theMeliton Hotel of Porto Carras on the middle leg (Sithonia)of the Chalkidiki peninsula in Macedonia, northern Greece, a place of exquisitebeauty and one of Panos’s favorite places. The conference was organized by SergiyButenko and Athanasios Migdalas and was attended by scientists from all over theworld. More than 50 members of this “Panos’s club” presented talks during thisevent.This volume is dedicated to Panos M. Pardalos, on the occasion of his 60thbirthday. The articles collected in this volume are based on selected talks presentedduring the conference. Several members of the Panos’s club could not attendconference, but have submitted their papers to this volume in order to honor him.The papers published in this volume cover a wide range of topics and presentrecent developments and surveys in research fields to which Pardalos has activelycontributed and promoted during his career.In addition, Panos’s spouse, Rosemary Bakker, has written a brief biographydescribing Panos’s exciting journey from a pastoral village on the high mountainsin Thessaly, central Greece, to a Distinguished Professorship at the University ofFlorida, that is, Panos’s own Odyssey. We therefore dedicate to him the first versesof Homer’s Odyssey and Cavaphes’ poem “Ithaka” believing that they accuratelydescribe Panos’s past, his present, and his future discovery voyages.We are indebted to Springer publishers and particularly to Razia Amzad for theirsupport in making the publication of this volume possible.</p
City Networking in Urban Strategic Planning
No full textCity networks are systems of relations through which cities can cooperate in order to face the challenges of economic development, social protection, and environmental sustainability. Consequently, city networking assists local authorities in carrying out their most distinctive function, i.e. the creation of public value in a financially sustainable way. This function has become increasingly complex, leading to a wide and growing interest in urban strategic planning, which, in fact, may offer a useful contribution to local government, as long as it is set and implemented in an authentic and substantial way. This paper aims to contribute to the definition and classification of city networking, analyse its involvement in the creation of public value, and underline its importance in urban strategic planning, identifying some critical points and providing some useful suggestions for the future
Sensitivity Analysis of Welfare, Equity, and Acceptability Level of Transport Policies
No full textTransport planners face a major challenge to devise policies to meet multiple expectations and objectives. While we know that transport networks are complex, multi-modal, and spatially distributed systems, there is now a long history of mathematical tools which assist planners in understanding travel movements. However, the objectives that they are asked to achieve do not always admit such a quantification, and so there is a potential mismatch between seemingly qualitatively driven objectives and quantitatively expressed models of the transport system. In the present chapter we address this mismatch, by focusing on three objectives that we believe represent the typical interests of a planner. These are namely: is the policy economically justifiable (efficient), is it “fair” (equitable), and is it justifiable to a democratic society (acceptable)? We provide mathematical representations of these three objectives and link them to mathematical theory of transport networks, in which we may explore the sensitivity of travel behaviour (and hence the objectives) to various multi-modal transport policies. The detailed steps for representing the policy objectives and sensitivities in the network are set out, and the results of a case study reported in which road tolls, road capacities, and bus fares are the policy variables. Overall, the chapter sets out a systematic method for planners to choose between multi-modal policies based on these three objectives
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