Antonella Meneghetti

The production planning process for a network of firms in the textile-apparel industry

Abstract The paper investigates how the decision variables of the production planning process for a network of firms in the textile-apparel industry, i.e. planning period length, material availability, the link between production orders and customer orders as regards colour mix, can affect the systems time performance, whose measurement has involved the creation of two new indicators. To adhere to reality, we studied and collected actual data from one of the most important Italian companies, the Benetton Group SpA and using these observations as a basis, a simulation model was built. Only the production planning period compression has been recognised as yielding a significant improvement in the external time performance. A relation between the external time performance and the internal time performance of the network is recognised. The cash flows associated with different lengths of the production planning period are analysed.

Traditional and innovative paths towards time-based competition

Abstract Time performances and time-based competition concepts are analysed, introducing three types of time-based competitors. A traditional and an innovative path towards time-based competition are then recognised, the former achievable by over-resource applying, while the latter by practices related to just-in-time and concurrent engineering. It is explained how making a firm structurally faster leads a company to face a “conversion dilemma”, i.e. to choose the proper strategic orientation that can be definitely regarded as affecting its external configuration, visible to the market, or only the internal one, transforming the time advantage into a cost one. Finally a matrix linking market sensitivity to external time performances and competitor typologies is proposed.

Greening the food supply chain: an optimisation model for sustainable design of refrigerated automated warehouses

An optimisation model for the sustainable design of refrigerated automated storage and retrieval systems is proposed, which takes into account specific features of the food supply chain, such as temperature control. Rack configuration as well as surfaces and volumes of the cold cell are conjointly optimised in order to minimise the total yearly cost of the automated storage facility, introducing energy requirements both for refrigeration and picking operations explicitly, other than investment costs. Crane plus satellite systems are modelled in order to enable deep lane solutions and space savings, as suitable for cold storage. The model allows a deep analysis of the impact of supply chain decision variables, such as the facility location, the storage temperature and the incoming product temperature on costs, energy use and carbon dioxide emissions, so that storage facilities attributes for supply chain design models can be properly assessed to re-optimise the whole cold chain. The design problem is modelled and solved by Constraint Programming in order to easily manage non-linear functions.

Perspectives on facilities management for industrial districts

The possible evolution of facility management (FM) in industrial districts, which characterise Italian industrial system, is analysed. The paper investigates structural features of industrial districts, mainly formed by small sized enterprises, and how they influence the attributes of the FM market. An aggregation matrix is introduced to identify technical opportunities such as replicated, centralised and distributed facilities and management for industrial districts. A positioning matrix for a district‐oriented FM is proposed, allowing FM providers to seize technical opportunities and to reap economies of scale and scope. Requisites and obstacles to the evolution of potential FM providers towards more competitive positions are outlined. The role of co‐operation with and among potential clients, in particular, together with information, is clarified. Considering the client’s perspective, the paper describes the forms of competitive advantage that can be gained through a district‐oriented FM by single enterprises and by an industrial district as a whole.

Design of forest biofuel supply chains

Designing and building new biofuel supply chains is an emerging theme in the present world energy situation. This paper considers a real-life problem of supplying a bioenergy plant with forest fuel. A mixed-integer linear programming model is proposed to determine the optimal configuration of that supply chain. The model proves helpful in resolving trade-offs between decentralised early treatment of biofuel, resulting in lower transportation costs, and centralised final treatment, allowing to reap economies of scale. It is therefore advisable to apply integrated supply chain planning concepts to design biofuel logistics systems and to support policy making in the energy field.

Sustainable storage assignment and dwell-point policies for automated storage and retrieval systems

Picking time reduction has been the traditional perspective for warehouse optimisation. When sustainability is considered, optimisation of warehouse operations should be read in terms of energy efficiency other than response time. Each location in the rack of an automated storage and retrieval system is associated with the value of energy consumed by the crane to reach it. Since picking performance strictly depends on storage location assignments, the time-based full turnover strategy is compared to the energy-based one. Three models of energy consumption are considered for traditional and new-generation cranes. Assignments are then compared in terms of dedicated zone shapes, time and energy performances within a given time horizon. Different shapes of the rack and product ABC curves are analysed. Dwell-point policies are also analysed from the new sustainable perspective, adding energy-saving performance to the traditional picking time reduction.

Rack shape and energy efficient operations in automated storage and retrieval systems

Energy efficiency has become a primary goal to be pursued for sustainable logistics. In automated storage and retrieval systems this leads to revise the traditional control policies aimed at picking time minimisation and to pay more attention to rack configuration, which has been not a research concern from the time-based perspective. Proper models for energy calculation should be developed by introducing new factors neglected in time analysis, such as the weight of unit loads and the differentiation of shifts along the horizontal and vertical axis as regard energy requirements, due to different contribution of gravity, inertia and friction. In this study, a classification of racks based on system height is proposed in order to select the proper crane specifications needed to compute the torque to be overcome by motors to serve a given location within a rack. An overall optimisation model based on Constraint Programming hybridised with Large Neighborhood Search is developed, allowing the joint application of the best control policies for storage assignment and sequencing both for time and energy-based optimisation, as well as the introduction of multiple weight unit loads and energy recovery. Simulations analysis is performed in order to assess the impact of the rack shape on energy saving. Results show how, regardless the demand curve and the optimisation objective, the best performances in terms of energy efficiency are reached by the intermediate height rack shapes, while the lower ones outperform when considering travel time performance.

Multiple-weight unit load storage assignment strategies for energy-efficient automated warehouses

Energy-efficient manufacturing claims for a change in warehousing operations management, moving from the traditional time-based perspective to the energy-based one. In automated storage and retrieval systems, this new approach leads to revise storage assignment policies, so that the least energy can be consumed by cranes for unit load movements. Dedicated energy-based policies and related zone shapes are analysed with particular attention to the role of unit load weight and the design option of rack stratification from floor to ceiling. Energy performance of dedicated, class-based, and random storage policies are then compared for different demand curves and rack shape. In order to enhance flexibility while maximising energy efficiency, new dynamic energy-based policies are also introduced and evaluated.

Waste-to-energy application in an industrial district

Industrial districts present some features that can be recognized and exploited in the plant engineering through the proposal of solutions which are not simple applications of models created for individual companies. This work illustrates a waste-to-energy plant to be used for the industrial waste of the district of Friuli Venezia Giulia. The project from the union between university and local entrepreneurs. It is described how the expense for woodworking-waste disposal can turn from a charge into an advantage for the firms of the district thanks to the incineration of this waste in a plant unique for the typology of waste treated. Each plant section is described in detail, underlining innovative approaches and solutions.

Decision Support Optimisation Models for Design of Sustainable Automated Warehouses

A new decision support tool for design of automated storage and retrieval systems is proposed. With the aim of promoting sustainable solutions, both economical and environmental perspectives are taken into account by two separated models, that can so properly been used to identify effective compromises or to consider different objectives of involved stakeholders. In order to reduce the gap between design practice, market component availability and existing mathematical models, the presented tool relies on a more realistic description of the rack structure in terms of bay configurations and components. Moreover, for the first time energy consumption for crane movements is introduced, with related impacts on costs and carbon dioxide emissions. Constraint programming is adopted in order to manage non-linear objective as well as constraints functions.