A Model for Periodic Preventive Maintenance Policy for a Series Parallel System

A linear programming model for optimal subassembly level determination in shipbuilding industry

Shipbuilding industry is an industrial sector characterized by a customized make-to-order production process. The shipbuilding process can be roughly divided into four steps: design, assembly planning, manufacturing and final assembly. In this paper assembly planning is investigated: it consists in subdividing the ship structure into blocks and grand-blocks, thus involving a two levels subassembly generation. Any mechanical assembly process can be decomposed into a set of tasks, each task involving joining two or more components or subassemblies together. The sequence of assembly tasks has a major influence on completion time and resource utilization and it drastically impacts costs and eff…

Comparing the Economic Effectiveness of Various Adaptive Schemes for the c Chart

In an attempt to improve the effectiveness of statistical process control (SPC) procedures, a variety of adaptive schemes has been developed in the last decades. However, considering control charts for attributes, relatively few works about adaptive schemes have been proposed, and most of them were proposed only recently. The common characteristic of those schemes is that one or more chart parameters are allowed to adaptively vary during the SPC operations according to the sampling information history, typically the current point plotted on the chart. In this way, the adaptive schemes are smarter than the related static ones, but they are also more complicated in terms of implementation. Th…

Towards more equity concerning quality of Urban Waste Management services in the context of cities

Abstract An innovative combined evaluation approach is proposed in the present paper to deal with the issue of the performance measurement and comparison of Urban Waste Management (UWM) services in the context of cities. The ELECTRE III method is initially considered as tool able to execute a multi-criteria analysis aimed at ranking UWM systems based on their integration and sustainability levels. The latter are comprehensively evaluated via the recently developed “Wasteaware” Integrated and Sustainability Waste Management indicators framework, which takes into account physical components and governance aspects of UWM systems. Then, on the basis on ELECTRE III results, a practical gaps inve…

A new innovative cooling law for simulated annealing algorithms

The present paper proposes an original and innovative cooling law in the field of Simulated Annealing (SA) algorithms. Particularly, such a law is based on the evolution of different initial seeds on which the algorithm works in parallel. The efficiency control of the new proposal, executed on problems of different kind, shows that the convergence quickness by using such a new cooling law is considerably greater than that obtained by traditional laws. Furthermore, it is shown that the effectiveness of the SA algorithm arising from the proposed cooling law is independent of the problem type. This last feature reduces the number of parameters to be initially fixed, so simplifying the prelimin…

L’identificazione dello stato di un processo mediante l’uso di reti neurali

Un qualsiasi processo è detto in controllo se i parametri della distribuzione di probabilità della variabile si mantengono costanti. Il metodo normalmente utilizzato per verificare lo stato di un processo fa uso delle carte di controllo. Con tale metodologia si mettono in evidenza comportamenti anomali del sistema quali particolari sequenze, e cioè comportamenti che hanno bassa probabilità di verificarsi per processi in controllo. L’identificazione dello stato del sistema è generalmente eseguito mediante l’esame visivo della carta: l’operatore alla qualità deve pertanto essere articolarmente addestrato per tenere conto delle numerose regole identificative dello stato di fuori controllo. Il …

Maintenance Planning For The Reliability Maximization In A Large System With Vagueness In The Reliability Values Of Some Components

This paper tackles the problem to single out the maintenance actions to be executed on a production system during the planned stop of given length. In detail, from a reliability viewpoint the system is assimilated as a series-parallel multi-component system and the maintenance actions need to maximize the system reliability up to the next planned stop. Moreover, it is assumed that some components reliability values are affected by vagueness within a given range. To solve the considered problem, an exact dynamic programming algorithm suitable to quickly point out the maintenance scheduling is developed and, moreover, it is formulated a proper parameter able to express the robustness of the o…

A combined fuzzy-SEM evaluation approach to identify the key drivers of the academic library service quality in the digital technology era: An empirical study

A conceptual model of the Academic Library (AL) service quality is hypothesized in the present article, and then validated and analyzed by a novel evaluation approach. Specifically, the conceptual model integrates the fundamental attributes of the canonical AL service together with those more relevant of the new and widely considered AL Electronic Service (e-services). As concerns the evaluation approach, it incorporates the Fuzzy Sets Theory (FST) so as to deal with the students' uncertainty over their own judgments on the AL service quality and a Structural Equation Model (SEM) to validate the conceptual model and to determine the key drivers of the AL service quality. The effectiveness o…

Optimal Maintenance For a System with Required Reliability

The effectiveness of a maintenance policy for a production system is generally measured by its availability. Nevertheless, for some production systems, the failure is a dangerous event for people or in any case too much expensive; therefore the failure probability must be maintained less than an accepted low value by a proper preventive maintenance policy. The system considered hereafter is schematized by a series of components some of them constituted by parallel-series sub-systems. The problem is to individuate the set of elements on which to operate the maintenance actions, providing the system functioning with the required reliability until the next planned maintenance instant by the mi…

Optimization of Opportunistic Maintenance Policies in a Global Service

The recent developments of innovative approaches and methodologies in maintenance process management have defined new market opportunities, not only for the users of the maintenance services, but also for the companies that specialize in maintenance process management. Nowadays, these companies are increasingly offering their maintenance services (maintenance global services), allowing both the users and providers of the services to focus on their core skills and resources. The engineering of maintenance processes and the implementation of effective maintenance strategies improve quality of services, allow the efficient management of human resources and reduce the size of the spare parts su…

Evaluation to support stakeholder centered design and continuous quality improvement in higher education services

Abstract: Evaluation and self-evaluation procedures are commonly used in educational institutions to measure education services and research performance. This chapter describes the main opportunities that evaluation-based approaches can produce to support processes of design and continuous quality improvement in higher education institutions in the light of recent normative measures in Italy to address quality aspects of education services. Subsequently, a new approach – based on the ServQual conceptual model – that evaluates education services is used to carry out a strategic analysis of education services at the management engineering program at the University of Palermo, Italy.

Economic Robustness Analysis of Adaptive Chart Schemes for Monitoring the Total Nonconformities Number in Inspection Units

In recent years, a variety of enhanced schemes for the c chart have been developed aimed at the effectiveness improving of the related statistical process control (SPC) procedures. However, the performance of such chart schemes can be very sensitive to values assumed for some operating and cost parameters, in particular to the considered process shift magnitude arising from out-of-control conditions. In such a circumstance, the effectiveness of such chart schemes can be subjected to substantial reductions when they are implemented in operative contexts given that, in practice, such value is unknown and it can be very difficult to accurately estimate. For this reason, in the present paper i…

Service quality benchmarking via a novel approach based on fuzzy ELECTRE III and IPA: an empirical case involving the Italian public healthcare context.

A novel fuzzy-based approach which combines ELECTRE III along with the Importance-Performance Analysis (IPA) is proposed in the present work to comparatively evaluate the service quality in the public healthcare context. Specifically, ELECTRE III is firstly considered to compare the service performance of examined hospitals in a noncompensatory manner. Afterwards, IPA is employed to support the service quality management to point out improvement needs and their priorities. The proposed approach also incorporates features of the Fuzzy Set Theory so as to address the possible uncertainty, subjectivity and vagueness of involved experts in evaluating the service quality. The model is applied to…

An efficient proposal for the application of simulated annealing algorithms

Complex nonlinear optimization problems require specific resolution techniques. These problems are often characterized by a solution space that presents many local optima. In these cases, local search algorithms, as the classical descent neighborhood search method, have a heavy drawback: the optimization algorithm generally converges towards a local minimum. To avoid getting trapped in a local minimum, the optimization algorithm must allow to accept worse solutions than the current one. Several kinds of algorithms have been ideated for this purpose and they differ for the acceptance criteria of a pejorative solution. Among such algorithms it is possible to remember the Taboo Search (TS) and…

THE EVALUATING OF THE IMPORTANCE WEIGHT OF STUDENT REQUIREMENTS USING ANALYTIC HIERARCHY PROCESS

A Multi-Objective Approach to Optimize a Periodic Maintenance Policy

The present paper proposes a multi-objective approach to find out an optimal periodic maintenance policy for a repairable and stochastically deteriorating multi-component system over a finite time horizon. The tackled problem concerns the determination of the system elements to replace at each scheduled and periodical system inspection by ensuring the simultaneous minimization of both the expected total maintenance cost and the expected global system unavailability time. It is assumed that in the case of system elements failure they are instantaneously detected and repaired by means of minimal repair actions in order to rapidly restore the system. A nonlinear integer mathematical programmi…

A Methodological Approach for Developing and Validating a Parsimonious and Robust Measurement Tool: The Academic E-Service Quality (ACEQUAL) Model

Nowadays, in the higher education sector, the quality measurement process of education-related services is assuming a crucial role to support focused and targeted improvement activities deeply centered on students’ needs/necessities. These are considered crucial factors for dealing with the current academic competitive context. Therefore, the quality measurement process has to be precise and accurate, namely the measurement model on which it is based has to be parsimonious and robust. The present work proposes an effective and easy-to-use methodological approach suitable for supporting the structuring of a measurement tool. Its effectiveness is shown with reference to the academic e-service…

Economic Design Approach for an SPC Inspection Procedure Implementing The Adaptive C Chart

The present paper proposes a design approach for a statistical process control (SPC) procedure implementing a c control chart for non-conformities, with the aim to minimize the hourly total quality-related costs. The latter take into account the costs arising from the non-conforming products while the process is in-control and out-of-control, for false alarms, for assignable cause locations and system repairs, for sampling and inspection activities and for the system downtime. The proposed economic optimization approach is constrained by the expected hourly false alarms frequency, as well as the available labor resource level. A mixed integer non-linear constrained mathematical model is dev…

ELECTRE III to dynamically support the decision maker about the periodic replacements configurations for a multi-component system

The problem tackled by the present paper concerns the selection of the elements of a repairable and stochastically deteriorating multi-component system to replace (replacements configuration) during each scheduled and periodical system stop within a finite optimization cycle, by ensuring the simultaneous minimization of both the expected total maintenance cost and the system unavailability. To solve the considered problem, a combined approach between multi-objective optimization problem (MOOP) and multi-criteria decision making (MCDM) resolution techniques is proposed. In particular, the @e constraint method is used to single out the optimal Pareto frontier whereas the ELECTRE III multi-cri…

An effective opportunistic maintenance policy for a global service

The aim of the present paper is to develop a model for an effective maintenance policy with refer to a global service contract between a services provider company and a company for the waste management. The contract requires, with fixed performance levels of the service, the supplying of a mandatory set of maintenance services on a set of waste compactors vehicles of the outsourcer company. In particular, the service provider (SP) must perform corrective maintenance actions and the replacement of the fault parts. The tackled problem concerns the determination of an effective opportunistic maintenance policy in order to assure the required service performance levels at the minimum global mai…

A Comparative Study of Mechanical and Microstructural Behavior for Metal Active Gas and Friction Stir Welded Micro-Alloyed Structural Steel

Manufacturing tiny components into gigantic structures seems unimaginable without welding connections, whether it is for materials, parts, structures, or equipment. In the recent competitive market scenario, manufacturing industries are desperately looking for a viable alternative to fusion-based conventional material joining technologies, to improve upon cost-effectiveness along with performance. The present investigation is to evaluate the performance of structural steel thick plate joints prepared by advanced solid-state friction stir welding (FSW) over conventional metal active gas welding (MAG). The FSW experiments were carried out with different tool designs and configurations. The ou…

An Effective Double Sampling Scheme for thecControl Chart

In the present paper is developed a statistical process control inspection procedure based on a new simple-to-implement and effective double sampling scheme for the c control chart, aimed at the minimization of the number of inspected observation units and warranting fixed levels for the type I and II error risks. In particular, the formulations of the false alarm risk α, the power P of the chart, and the expected number of inspected observation units for the developed inspection procedure are given, whereas a macro of Microsoft Excel is adopted to solve the tackled problem. In order to illustrate the application of the developed approach and to investigate on the influence of several opera…

IMPIANTO POLIFUNZIONALE PER UNA STRUTTURA OSPEDALIERA

Nel presente lavoro si è di affrontato lo studio di un impianto polifunzionale per la produzione di ossigeno, energia elettrica e termica a servizio di una importante struttura ospedaliera. L’articolo prende spunto da una precedente ricerca in cui si era studiata la convenienza tecnico‐economica di impianto on‐site per la produzione di ossigeno medicale nella quale era stata rilevata l’influenza significativa del costo energetico. Sono state esaminate varie soluzioni impiantistiche con particolare riferimento ai problemi tecnico/economici e alle prospettive del mercato energetico in continua evoluzione anche sotto il profilo della liberalizzazione normativa. Dalle analisi effettuate sulla b…

A Multi-Objective Design Approach for the c Chart Considering Taguchi Loss Function

The present paper proposes a multi-objective design approach for the c chart, considering in the optimization process of the chart parameters both the statistical and the economic objectives. In particular, the minimization of the hourly total quality related costs is the considered objective to carry out the economic goal, whereas the statistical objective is reached by the minimization the out-of-control average run length of the chart. A mixed integer non-linear constrained mathematical model is formulated to solve the treated multi-objective optimization problem, whereas the Pareto optimal frontier is described by the e-constraint method. In order to show the employment of the proposed …

A Multi-Objective Design Approach for the c Chart Considering Taguchi Loss Function

The present paper proposes a multi-objective design approach for the c chart, considering in the optimization process of the chart parameters both the statistical and the economic objectives. In particular, the minimization of the hourly total quality related costs is the considered objective to carry out the economic goal, whereas the statistical objective is reached by the minimization the out-of-control average run length of the chart. A mixed integer non-linear constrained mathematical model is formulated to solve the treated multi-objective optimization problem, whereas the Pareto optimal frontier is described by the «-constraint method. In order to show the employment of the proposed …

A Combined Fuzzy-SEM Evaluation Approach to Identify the Key Drivers of the Academic Library Service Quality in the Digital Technology Era: An Empirical Study

A conceptual model of the Academic Library (AL) service quality is hypothesized in the present article, and then validated and analyzed by a novel evaluation approach. Specifically, the conceptual model integrates the fundamental attributes of the canonical AL service together with those more relevant of the new and widely considered AL Electronic Service (e-services). As concerns the evaluation approach, it incorporates the Fuzzy Sets Theory (FST) so as to deal with the students’ uncertainty over their own judgments on the AL service quality and a Structural Equation Model (SEM) to validate the conceptual model and to determine the key drivers of the AL service quality. The effectiveness o…

The New Nino Capability Index for Dynamic Process Capability Analysis

The process capability analysis is a crucial activity to evaluate if the process outcome meets the design specifications. Classically, such analysis is performed by verifying the in-control condition of the process and evaluating suitable capability indices, by assuming the process in-control steady-state condition. However, the in-control period of the process characterizes only a part of the system functioning cycle, the one with the lower defective rate. In particular, the system functioning cycle is also characterized by the out-of-control period, during which a greater defective rate is produced, and such increasing is not considered by the widely adopted capability indices. As consequ…

A methodological framework based on a DANP model for evaluating the software quality in terms of usability: a preliminary investigation on mobile operating systems

Evaluation of the software usability as concerns software alternatives represents a typical Multi- Criteria Decision-Analysis (MCDA) problem. Such a kind of problem can be successfully faced via structured models and approaches which validity have been widely shown in literature. In this work, a methodological framework based on a MCDA model integrating the DEMATEL method along with the ANP technique is proposed and explained with more detail to address the relevant issue of the software usability evaluation. The applicability of the considered DEMATEL-ANP (DANP) based model in the under analysis contest is demonstrated via a preliminary investigation, where the usability of the two major M…

La valutazione della qualità percepita nel servizio di trasporto pubblico palermitano

A Multi-Criteria Group Decision To Support The Maintenance Service: A Case Study

The present paper wants to propose a methodology to support a group of decision makers into the choice of actions, to implement on a multi-component system, regarding the maintenance service. The choice has to be made on the basis of several criteria, namely the total maintenance cost, the system unavailability and by considering the maintenance actions feasibility. In particular, with the aim to select the maintenance service that represents for the group the best comprise among the criteria to satisfy, the proposed methodology consists of two multi-criteria decisions methods to apply in two successive phases. The first one regards the application of the Analytic Hierarchy Process (AHP) to…

The New Nino Capability Index for Dynamic Process Capability Analysis

The process capability analysis is a crucial activity to evaluate if the process outcome meets the design specifications. Classically, such analysis is performed by verifying the in-control condition of the process and evaluating suitable capability indices, by assuming the process in-control steady-state condition. However, the in-control period of the process characterizes only a part of the system functioning cycle, the one with the lower defective rate. In particular, the system functioning cycle is also characterized by the out-of-control period, during which a greater defective rate is produced, and such increasing is not considered by the widely adopted capability indices. As consequ…

An Effective Double Sampling Scheme for the c Control Chart

In the present paper is developed a statistical process control inspection procedure based on a new simple-to-implement and effective double sampling scheme for the c control chart, aimed at the minimization of the number of inspected observation units and warranting fixed levels for the type I and II error risks. In particular, the formulations of the false alarm risk α, the power P of the chart, and the expected number of inspected observation units for the developed inspection procedure are given, whereas a macro of Microsoft Excel is adopted to solve the tackled problem. In order to illustrate the application of the developed approach and to investigate on the influence of several opera…

A fuzzy ServQual based method for reliable measurements of education quality in Italian higher education area

In recent years, the attention that the European Community has focused on the education sector has produced a new university commitment addressed to quality aspects for all education related services. In fact, a quality oriented service requires excellence in the design and planning of service activities, as well as during its delivering and also for the adopted service performance evaluation method. However, considering that service performance evaluations are deeply based on stakeholders' judgments, they can be characterized by possible uncertainties related to incompleteness for partial ignorance, imprecision for subjectivity and even vagueness. Therefore, under these conditions, unrelia…

A knowledge-based exploratory framework to study quality of Italian mobile telecommunication services

A novel two-step knowledge-based exploratory framework is proposed in this paper for studying quality of Italian Mobile Telecommunication Services (MTSs). Particularly, the Delphi technique is initially considered to finalize an overall quality structure of MTSs features, indicators and drivers, herein described on the basis of a comprehensive review of the fundamental references for the field, and also to select the key elements with reference to the Italian context. At the second step, selected key elements are prioritized via the Analytic Hierarchical Process (AHP) method according to viewpoints of the fundamental stakeholders for the sector. Furthermore, possible uncertainty and ambigui…

Economic design approach for a SPC inspection procedure implementing the adaptive c chart

The present paper proposes a design approach for a statistical process control (SPC) procedure implementing a c control chart for non-conformities, with the aim to minimize the hourly total quality-related costs. The latter take into account the costs arising from the non-conforming products while the process is in-control and out-of-control, for false alarms, for assignable cause locations and system repairs, for sampling and inspection activities and for the system downtime. The proposed economic optimization approach is constrained by the expected hourly false alarms frequency, as well as the available labor resource level. A mixed integer non-linear constrained mathematical model is dev…

An effective approach for the maintenance scheduling in large systems with required reliability level: A case study

This paper deals with the problem of the maintenance scheduling in a multi-component system for which a required reliability level has to be warranted until the next planned stop for maintenance. Particularly, the tackled problem concerns both the determination of the elements set on which to perform preventive maintenance and the optimal number of maintenance crews in order to warranty the required reliability level at the minimum maintenance cost. The problem is formulated as a mathematical programming model that becomes very hard to solve for large practical systems. For such reason, a new effective approach based on a constrained genetic algorithm is herein proposed and tested with refe…

Robust Maintenance Scheduling for Reliability Maximization

The present paper aims to single out the maintenance actions to perform on a system constrained to be maintained only during some planned stops. Since system failure implies costs and risks for people and/or the environment, then it is necessary to minimize the probability of its occurrence. Thus, maintenance actions need to maximize the system reliability up to the next planned stop, in respect to some constraint. The originality of the problem discussed in the present paper lies in considering reliability values affected with uncertainty within a range of vagueness. Consequently, a further problem is added to the constrained reliability maximization, that is the search for a robust soluti…

A new capability index for dynamic process analysis

Nowadays, the trend to produce with reduced specification limits width and at a low defectives rate seems to be irreversible. In such conditions, reliable evaluation of the process capability level represents a crucial activity to assess the quality related performance of a production process. By adopting the classical approach, such evaluation is performed by verifying the process in-control condition and by evaluating suitable capability indices. However, considering the natural dynamic behavior of production processes, i.e. the process variability over the time domain, the in-control condition characterizes only a part of the production process functioning cycle, the one with the lowest …

A fuzzy framework to evaluate service quality in the healthcare industry: An empirical case of public hospital service evaluation in Sicily

A novel fuzzy framework is considered to analyze healthcare service quality.The fundamental quality structure of healthcare service delivered in Sicily is described.The public healthcare in Sicily (Italy) is strategically analyzed.Strategic stakeholders' oriented implications for healthcare improvements are given. A novel fuzzy evaluation framework is applied in this study to evaluate service quality in the public healthcare sector. In particular, the proposed framework is based on the ServQual disconfirmation paradigm and incorporates the Analytic Hierarchy Process (AHP) method to elicit reliable estimations of service quality expectations. Moreover, degrees of uncertainty, subjectivity an…

ECONOMIC-STATISTICAL DESIGN APPROACH FOR A VSSI X-BAR CHART CONSIDERING TAGUCHI LOSS FUNCTION AND RANDOM PROCESS SHIFTS

Economic design approaches of control charts are commonly based on the assumption that various cost parameters values and the occurrence risk of assignable causes have to be a priori known with precision. However, in real operative contexts, such parameters can be really difficult to accurately estimate, especially considering costs arising from out-of-control conditions of the process. As consequence, pure economic design approaches can involve chart schemes with low statistical performance. To overcome such limitation, it is herein proposed a multi-objective economic-statistical design approach for an adaptive X-bar chart. In particular, such approach aims at the minimization of both the…

Non-dominated “trade-off” solutions in television scheduling optimization

The main approaches for the television scheduling design are commonly based on the ratings or revenues maximization objective, and thus, only a single optimal solution can be obtained, corresponding to the best result for the considered objective. Therefore, these approaches lead up to the alternative solutions loss which, even if less effective from the ratings or revenues maximization viewpoint, may be more suitable for the decision maker because of better compromise in relation to factors influencing the decision process. Specifically, such a compromise could be achieved through a suitable “trade-off” between these factors, with reference to the decision context in which the decision mak…

Handling stakeholder uncertain judgments in strategic transport service analyses

Abstract The quality level of services has to be constantly controlled, especially under conditions of competition increasing and limited resources. However, considering that service performance analyses are based on stakeholders' judgments, they can be characterized by possible uncertainties related to incompleteness for partial ignorance, imprecision for subjectivity and even vagueness. Therefore, under these conditions, unreliable results can be obtained by widely used service analysis methodologies. In the present paper, a methodology based on a recent extension of the SERVQUAL model, and that uses in combined manner the fuzzy set theory and the analytic hierarchy process method is prop…

Strategic resource management for human intensive project based up on a multi-mode multi objective genetic scheduler

A multi-decision makers approach to select the maintenance plan for a multi-component system.

DINESERV along with fuzzy hierarchical TOPSIS to support the best practices observation and service quality improvement in the restaurant context

Abstract The present work proposes a new Multi-Criteria-Decision-Analysis (MCDA)-based approach integrating the DINESERV model along with the hierarchical TOPSIS method as measurement tool for evaluating quality in the restaurant services context. More in detail, on the basis of the DINESERV theoretical framework of the restaurant service quality, hierarchical TOPSIS is applied to compare quality of restaurant services. Actually, due to the prioritization process of hierarchical TOPSIS, investigated services providers are consistently and effectively assessed against criteria and sub-criteria of DINESERV, so allowing the identification of both best practices and weaknesses of delivered serv…

Handling the epistemic uncertainty in the selective maintenance problem

Abstract Nowadays, both continuous and discontinuous operating systems require higher and higher reliability levels in order to avoid the occurrence of dangerous or even disastrous consequences. Accordingly, the definition of appropriate maintenance policies and the identification of components to be maintained during the planned system’s downtimes are fundamental to ensure the reliability maximization. Therefore, the present paper proposes a mathematical programming formulation of the selective maintenance problem with the aim to maximize the system’s reliability under an uncertain environment. Specifically, the aleatory model related to the components’ failure process is well known, where…

Optimal pareto solutions of a dynamic C chart: An application of statistical process control on a semiconductor devices manufacturing process

The present paper proposes a novel economic-statistical design procedure of a dynamic c control chart for the Statistical Process Control (SPC) of the manufacturing process of semiconductor devices. Particularly, a non-linear constrained mathematical programming model is formulated and solved by means of the ε-constraint method. A numerical application is developed in order to describe the Pareto frontier, that is the set of optimal c charts and the related practical considerations are given. The obtained results highlight how the performance of the developed dynamic c chart overcome that of the related static one, thus demonstrating the effectiveness of the proposed procedure.

Fuzzy ServPerf model combined with ELECTRE III to comparatively evaluate service quality of international airports in Sicily

In this paper a new approach was proposed so as to comparatively evaluate the quality of service alternatives. In particular, a fuzzy extension of the ServPerf service conceptual model was considered to estimate quality scores of fundamental service criteria, whereas the non-compensative multi-criteria decision-making ELECTRE III method was employed to point out the quality ranking of service alternatives on the basis of which the comparative service quality analysis was performed. In order to show the effectiveness of the proposed approach, an empirical study concerning service quality evaluation of the three international airports in Sicily (Italy) was conducted with detailed proposals fo…

Comparing the Economic Effectiveness of Various Adaptive Schemes for the c Chart

In an attempt to improve the effectiveness of statistical process control (SPC) procedures, a variety of adaptive schemes has been developed in the last decades. However, considering control charts for attributes, relatively few works about adaptive schemes have been proposed, and most of them were proposed only recently. The common characteristic of those schemes is that one or more chart parameters are allowed to adaptively vary during the SPC operations according to the sampling information history, typically the current point plotted on the chart. In this way, the adaptive schemes are smarter than the related static ones, but they are also more complicated in terms of implementation. Th…

Determination of Pareto frontier in multi-objective maintenance optimization

Abstract The objective of a maintenance policy generally is the global maintenance cost minimization that involves not only the direct costs for both the maintenance actions and the spare parts, but also those ones due to the system stop for preventive maintenance and the downtime for failure. For some operating systems, the failure event can be dangerous so that they are asked to operate assuring a very high reliability level between two consecutive fixed stops. The present paper attempts to individuate the set of elements on which performing maintenance actions so that the system can assure the required reliability level until the next fixed stop for maintenance, minimizing both the globa…