Generating Alternatives for Siting Using Genetic Algorithms and Multiple Criteria Decision Techniques

It is believed that a fundamental step in the structuring of a siting problem is generating alternati-ves. This task should occur at the beginning of a process for facility location, giving a preliminary insight into the feasibility of the project in the area of concern by identifying a manageable number of feasible alternatives for careful review and consideration. The purpose of this paper is to present a methodology aimed at generating alternatives for siting of facilities taking into account a number of criteria. These criteria comprise environmental, economical and the action's inherent technical aspects. The search is carried out by applying genetic algorithms (GA's) which are natural phenomena based algorithms for optimization and random search procedures. According to the GA's terminology, a fitness function measures the worth of each candidate alternative codified into a chromosome. It was thought that the merging of aspects of multiple criteria theory and genetic algorithms is essential for the problem of generating alternatives in location problems. The aim of this integration is the improvement of the theoretical principles upon which the fitness function is based, leading to the construction of a robust set of alternatives. The paper describes the integration of both multiple criteria theory and GA's and discusses the results

MCDA: Multiple Criteria Decision Aiding

European Commissio

Decision Support for Siting Problems

: Despite the development of mathematics of location theory and despite its obvious economic impact, few applications have been developed and are actually in use to support decision makers in siting decisions. The obstacles that hinder a more widespread exploitation of mathematical results are twofold: the intrinsic difficulties of the relevant problems and the tradeoff to be balanced between the different objectives. The article presents the results obtained in the implementation of a Decision Support system applied to a specific siting problem: the location of installations for industrial waste management. This DSS is based on multicriteria decision analysis for the best siting of plants, optimizing costs and environmental impacts. The proposed approach individuates a hierarchy of objectives, where at top-level a k-best solution of the problem of minimizing a distance measure is computed, to reduce the space of alternatives. Specifically, the problem solved at top level has been math..

L'ingrandimento radiografico nello studio delle malattie della mano. Tecniche digitale e tradizionale a confronto

The electronic magnification of digital images was compared with direct digital magnification and with plain radiograph magnification. A whole-body computed radiographic system with photostimulable phosphor plates contained inside standard X-ray cassettes was used. The small bones of the hands and wrists of 18 patients with traumatic (10 cases) or degenerative (8 cases) bone conditions mainly due to chronic renal failure were studied. Each patient was examined with all three techniques: the images were retrospectively reviewed by four observers relative to resolution, contrast, visibility of the lesions and diagnostic value of each method. The statistical analysis of our results demonstrated better yield of direct digital magnification than of plain radiograph (p = 0.00043) and of electronic (p = 7.5 10(-13) magnification. This finding was mainly due to density and contrast optimization of digital images, in spite of their low spatial resolution. This feature allows good simultaneous representation of structures with different radiographic densities, as it happens in the hand and wrist. Electronic magnification yielded less brilliant results, even if compared with plain radiographic studies (p = 0.0032). However, this limitation was compensated for by the fact that this technique is easier and quicker to perform and that it does not require any additional X-ray exposure

A decision support system for urban waste management

Abstract: The objective of the project we present is that of implementing and validating a decision support system for urban waste management on a regional area, to be used as a means for evaluating general policies for regional service organisation and, in particular, for identifying areas suitable for locating waste treatment and disposal plants, with special reference to controlled landfill plants. The system works on a prototypical case study, which refers to an area composed of specifically selected provinces in Sicily. For the design and implementation of the system, several topics have been considered, such as the identification of a representative case study, the identification and collection of relevant information and its structuring in databases, the design of combinatorial optimisation algorithms for solving the core location problem, the study of models for evaluating the different alternatives and their framing in a complete multicriteria decision model, the choice of hardware and system software suitable for the implementation of a decision support system supporting all above mentioned activities, and, finally, the solution of the case study by means of the DSS