Maurizio Faccio

Waste collection multi objective model with real time traceability data.

Waste collection is a highly visible municipal service that involves large expenditures and difficult operational problems, plus it is expensive to operate in terms of investment costs (i.e. vehicles fleet), operational costs (i.e. fuel, maintenances) and environmental costs (i.e. emissions, noise and traffic congestions). Modern traceability devices, like volumetric sensors, identification RFID (Radio Frequency Identification) systems, GPRS (General Packet Radio Service) and GPS (Global Positioning System) technology, permit to obtain data in real time, which is fundamental to implement an efficient and innovative waste collection routing model. The basic idea is that knowing the real time data of each vehicle and the real time replenishment level at each bin makes it possible to decide, in function of the waste generation pattern, what bin should be emptied and what should not, optimizing different aspects like the total covered distance, the necessary number of vehicles and the environmental impact. This paper describes a framework about the traceability technology available in the optimization of solid waste collection, and introduces an innovative vehicle routing model integrated with the real time traceability data, starting the application in an Italian city of about 100,000 inhabitants. The model is tested and validated using simulation and an economical feasibility study is reported at the end of the paper.

Consignment stock inventory model in an integrated supply chain

The consignment stock (CS) is an innovative approach to manage inventories in which the vendor removes his inventory and maintains a stock of materials at the buyers plant. The aim of this paper is to promote a successful application and comprehension of the CS policy both in literature and practice. In this paper, we deal with a multi-echelon inventory system in which one vendor supplies an item to multiple buyers. The study develops a single-vendor and multi-buyer consignment stock inventory model in which many clients can establish a CS policy with the same vendor. The aim of the paper is to evaluate the real economical and logistic benefits from the point of view of both the partners and the whole supply chain, following the adoption of a CS policy. We determine the maximum and minimum inventory stock levels to store in the buyers’ plant warehouse and the optimal quantity delivered from the vendor to each buyer in order to minimise total supply chain costs. Space constraints in clients’ plant warehouse, stock-out risk due to the variability of consumption and obsolescence risk for the materials stored are also considered.

Kanban number optimisation in a supermarket warehouse feeding a mixed-model assembly system

Following just-in-time principles, a growing number of manufacturers are adopting the so-called supermarket concept. Supermarkets are decentralised storage areas scattered throughout the shopfloor that serve as an intermediate store for parts required by nearby assembly lines. From these stores, a certain number of handling operators deliver parts from the supermarket to, and collect empty bins from, assembly stations. Finally, they return to the supermarket and are refilled for their next tours. The assembly stations are typically refilled from the supermarket through the constant replacement of the consumed parts pulled by the kanban system. Considering a mixed model assembly system composed of different assembly lines, feeding problems can occur as an effect of the replenishment lead time, of the production mix variation, of the commonality between the different models assembled. The aims of this paper are (i) to highlight how the supermarket/multi-mixed assembly-line system presents specific attributes that prohibit the simple application of well-known kanban dimensioning formulations and (ii) to provide an innovative procedure to optimally set all decision variables related to such a feeding system.

Sustainable SC through the complete reprocessing of end-of-life products by manufacturers: A traditional versus social responsibility company perspective

Every item produced, transported, used and discarded within a Supply Chain (SC) generates costs and creates an impact on the environment. The increase of forward flows as effects of market globalization and reverse flows due to legislation, warranty, recycling and disposal activities affect the ability of a modern SC to be economically and environmentally sustainable. In this context, the study considers an innovative sustainable closed loop SC problem. It first introduces a linear programming model that aims to minimize the total SC costs. Environmental sustainability is guaranteed by the complete reprocessing of an end-of-life product, the re-use of components, the disposal of unusable parts sent directly from the manufacturers, with a closed loop transportation system that maximizes transportation efficiency. Secondly, the authors consider the problem by means of a parametrical study, by analyzing the economical sustainability of the proposed CLSC model versus the classical Forward Supply Chain model (FWSC) from two perspectives: Case 1, the ‘traditional company perspective’, where the SC ends at the customers, and the disposal costs are not included in the SC, and Case 2, the ‘social responsibility company perspective’, where the disposal costs are considered within the SC. The relative impact of the different variables in the SC structure and the applicability of the proposed model, in terms of total costs, SC structure and social responsibility, are investigated thoroughly and the results are reported at the conclusion of the paper.

Fully flexible assembly systems (F‐FAS): a new concept in flexible automation

Purpose – Flexible automated assembly is an emerging need in several industries. The purpose of this paper is to address the introduction of an innovative concept in flexible assembly: the fully flexible assembly system (F‐FAS).Design/methodology/approach – After an analysis of the state of the art, the authors describe the proposed F‐FAS, from a layout, constitutional elements, functioning principles and working cycle point of view. Second, the authors compare the traditional FAS and the manual assembly system versus the proposed F‐FAS according to their throughput and unit production costs, deriving a convenience map as a function of the number of components used in assembly and of the efficiency of the F‐FAS. Finally, using a prototype work cell developed at the Robotics Laboratory of University of Padua, the authors validate the F‐FAS concept.Findings – Results of the research indicate that the concept of full‐flexibility can be exploited to bring automation to a domain where traditional FAS are not c...

A new methodological framework to implement an RFID project and its application

The introduction of new technologies in the industrial field has consistently seen the development of several different projects: some have been carried out successfully and others have encountered many difficulties, resulting in the failure of the projects. Often this is caused by the lack of the correct methodology to tackle the project and to understand how the new technology could be used in industrial applications. At present, radio frequency identification (RFID) technology represents a new tool of support for the automation of the processes and the improvement of the operating management of a system, being the missing link between the material flow and the information flow. RFID technology is used in a large number of possible applications, like product tracking, animal identification, inventory systems and others. However, in recent years, an inconsistent increase of such applications has been observed, due to the diverse information available on such technology and to the lack of a support method...

Inventory holding costs measurement : a multi-case study

Purpose – Logisticians in the worldwide industry are frequently faced with the problem of measuring the total cost of holding inventories with simple and easy-to-use methodologies. The purpose of this paper is to look at the problem, and in particular illustrate the inventory holding cost rate computation, when different kind of warehousing systems are applied. Design/methodology/approach – A multiple case study analysis is here developed and supported by a methodological framework directly derived from the working group discussions and brainstorming activities. Two different field of application are considered: one related to five companies with manual warehousing systems operating with traditional fork lift trucks; the other is among five companies operating with automated storage/retrieval systems (AS/RS) to store inventories. Findings – The multi-case study helps to understand how the holding cost parameter is currently computed by industrial managers and how much the difference between manual and aut...

Mixed model assembly system with multiple secondary feeder lines: layout design and balancing procedure for ATO environment

The constant research for efficiency and flexibility has forced assembly systems to change from simple/single assembly lines to mixed model assembly lines, while the necessity to reduce inventory has led the transition from single to multi-line systems, where some components are assembled in secondary lines, called feeder lines, connected to the main one by a ‘pull philosophy’. A possible approach to configure such an assembly system is to balance the main line first and use the retrieved cycle time to balance each feeder line separately, which is a questionable solution, especially if operators can perform tasks on both the feeder and the main line. Moreover for its complexity the mixed model balancing problem is usually solved transforming it into a single model by creating a single ‘virtual average model’, representative of the whole production mix. The use of a virtual average model assumes that the processing times of some models are higher or lower than the cycle time, which creates overload/idle time at the stations. This approach, especially in complex multi line production systems, largely reduces the assembly line productivity and increases the buffers dimensions. This paper faces the mixed model assembly line balancing problem in the presence of multiple feeder lines, introducing an innovative integrated main-feeder lines balancing procedure in case of unpaced assembly systems. The proposed approach is compared with the classical one and validated through simulation and industrial applications.

Modelling and optimization of fully flexible assembly systems (F‐FAS)

Purpose – The paper aims to address the modelling and optimization of fully flexible assembly systems (F‐FAS), a new concept in flexible automation recently introduced by the authors.Design/methodology/approach – The paper presents a mathematical model of the F‐FAS, which makes it possible to predict its efficiency, throughput and unit direct production costs, correlating such values with system and production variables. The mathematical model proposed in the paper was derived from experimental and simulation data, which were analysed for a wide range of different productions and system settings.Findings – Correlation analysis revealed that there are three main determinants of the efficiency of the F‐FAS: the number of components (types of parts) used to assemble the models (production variable); the average complexity of the models to be assembled (production variable); the ratio of the average perimeter of components (production variable) over a significant dimension of the working plane (system variabl...

Multi-stage supply network design in case of reverse flows: a closed-loop approach

Design of distribution networks is one of the most critical issues in the management of supply networks. When the supply chain takes into account the whole life of the product (warranty, remanufacturing, recycle, disposal, etc.), the adverse effects on the logistic flow is quite considerable on the structure of the network. For this reason, these aspects should be considered in network design. This paper addresses the possibility to apply different supply chain (SC) design approaches in presence of reverse flows, analysing the network structure where the considered flows are forward flow exclusively, or forward and reverse flows, or integral closed-loop flows. The study also presents an integrated methodology in closed-loop network design, based on mixed-integer programming, considering as inputs the most important driver as fixed and variable costs (installation, transportation, handling, inventory and production), facilities attributes (type, location, capacity and costs), stochastic demand, multi-echelon, multi-product, multi-production, multi-distribution and multi-transportation system. A real industrial application to validate the proposed closed-loop SC design methodology and a comparison between different SC design approaches are presented as a result of this paper.