196,313 research outputs found
A Timed Petri Nets Model for Performance Evaluation of Intermodal Freight Transport Terminals
No full textThis paper presents a general modeling framework for Intermodal Freight Transport Terminals (IFTTs). The model allows simulating and evaluating the performance of such key elements of the intermodal transportation chain. Hence, it may be used by the decision maker to identify the IFTT bottlenecks, as well as to test different solutions to improve the IFTT dynamics. The proposed modeling framework is modular and based on timed Petri Nets (PNs), where places represent resources and capacities or conditions, transitions model inputs, flows, and activities into the terminal and tokens are intermodal transport units or the means on which they are transported. The model is able to represent the different types of existing IFTTs. Its effectiveness is tested first on an example from the literature and then on a real case study, the railroad inland terminal of a leading Italian intermodal logistics company, showing its ease of application. In the real case study, using the proposed formalism we test the as-is IFTT performance and evaluate alternative possible to-be improvements in order to identify and eliminate emerging criticalities in the terminal dynamics
A proposal for a flexible and scalable system for environmental measurement network
No full textThe aim of this work is to present the new activities planned by the Electric and Electronic Measurements Research Group of Polytechnic of Bari, Department of Electric and Information Engineering, under the strategic project named "Magna Grecia - Rafforzamento Strutturale", funded by the Italian Ministry of Education, University and Research within the National Operating Program Research and Competitiveness 2007-2013. The project aims to cooperate with many Apulia Regional Authorities to build a network for the monitoring of many pollution sources in the State of Taranto, which have already caused and continue to cause a heavy degradation of air, water, soil and electromagnetic spectru
Process Re-engineering Based on Colored Petri Nets: the Case of an Italian Textile Company
No full textBusiness process re-engineering is crucial for manufacturing companies to improve their productivity and efficiency. The identification of the main criticalities affecting the production processes and the implementation of effective re-engineering solutions can significantly reduce the company losses. However, such actions can be unsuccessful if suitable preliminary investigations on the effectiveness of the solutions are not performed. This paper proposes an integrated process re-engineering technique that allows to: identify workflows via the Unified Modeling Language; model and simulate the business process via Colored Petri Nets (CPNs); detect bottlenecks and waste sources through the Value Stream Mapping tool; rank the impact of the detected criticalities via a mathematical formulation of the Genba-Shikumi lean philosophy; simulate the re-engineering actions and evaluate their effectiveness using the CPN model. The aim is to offer an intuitive tool for strategic decision making, deployable at a managerial level in a digital twin approach. The proposed technique is tested on a textile company located in Southern Italy, showing its effectiveness in removing inefficiencies and ensuring the continuous improvement of the production process
A Survey on Petri Net Models for Freight Logistics and Transportation Systems
No full textThe benefits of logistics and transportation systems to citizens, economy, and society can strongly increase when considering a smart, safe, and environmentally friendly management. This results in the implementation of intelligent transportation systems that combine innovative technologies and transportation frameworks at the aim of finding proper solutions to the related decision problems. To achieve such a goal, the intrinsic discrete event dynamics of these systems should be considered when deriving a model to be used for simulation, analysis, optimization, and control. Among the different discrete event models, Petri Nets (PNs) are particularly effective due to a series of relevant features. In addition, several high-level PN models (e.g., colored, continuous, or hybrid) allow the solution of complex and large-dimension problems that typically arise from real-life applications in the area of freight logistics and transportation systems. This paper presents a survey on contributions in this area. Papers are classified according to the addressed problem, namely, strategic/tactical or operational decision-making-level problem, and the adopted PN formalism. We also debate the approaches' viability, discussing contributions and limitations, and identify future research directions to enhance the successful application of PNs in freight logistics and transportation systems
Efficient Resource Planning of Intermodal Terminals under Uncertainty
No full textThis paper presents a decision support tool for the efficient resource planning and management of intermodal terminals under uncertainty, allowing to address the planning issue under imprecise or uncertain data (e.g., estimates on flows, resource utilization, operating conditions). The procedure consists of three steps: 1) the definition of a Timed Petri Net model of the terminal; 2) the computation of suitable performance indices to evaluate whether the current configuration is able to cope with a foreseen increase in the freight flows; 3) in the case of not satisfactory values of the indices at the previous step, the simulation of alternative planning solutions and the detection of the most efficient one via a cross efficiency fuzzy Data Envelopment Analysis technique. In order to test its effectiveness, the procedure is applied to a real case study. (C) 2018, IFAC (International Federation of Automatic Control) Hosting by Elsevier Ltd. All rights reserved
Analisi spaziale degli effetti sulla salute dell’inquinamento ambientale da amianto nella città di Bari
No full textDecision and Control Approaches for Enhancing the Resilience of Distribution Networks: a Survey
No full textRecently, the concept of resilience of electrical infrastructures has been introduced to quantify the ability of the grid to resist, adapt to, and rapidly recover after the occurrence of high-impact and low-probability (HILP) events. Various surveys discuss the state of the art on the resilience of distribution networks (DNs), which are a subsystem of the electrical infrastructure particularly susceptible to HILP events. It emerges that automation has a central role in guaranteeing and enhancing DNs resilience, although a classification of the existing contributions is missing. To fill this gap, in this paper we review the literature contributions regarding decision and control methods to enhance the resilience of DNs. We classify the reviewed approaches into tactical/strategic and operational level ones, we group them by the time of application and type, and finally we provide a detailed discussion and comparison of the available methods, highlighting open issues and future trends in this field
Logistics 4.0: A Matheuristics for the Integrated Vehicle Routing and Container Loading Problem
No full textThe increasing demand for freight transport requires logistic companies to improve their competitiveness by ensuring high service levels at limited costs. This paper investigates the problem of defining delivery plans with the aim to support logistic companies in reducing planning times and freight delivery costs. In delivery planning, given a set of delivery requests, both the routes and load configurations of Transport Units (TUs) are to be established. In the literature, this problem is defined as Three-dimensional Loading Capacitated Vehicle Routing Problem with Time Windows (3LCVRPTW). However, these problems are generally tackled separately and referred to as the vehicle routing problem and the container loading problem, respectively. Moreover, only a few contributions present solution approaches for real logistic systems, and these methods are mainly based on heuristics. In this work, we define a novel matheuristic algorithm for the integrated solution of the vehicle routing problem and container loading problem. The proposed method is suitable for real logistic applications and combines the advantages of exact solutions with the rapidity of heuristics. The approach aims at minimizing the total travel costs and the clients' time windows violations in the routes' definition, while optimizing the configuration of the cargo inside each TU. The developed matheuristic algorithm is tested both on a well-known literature benchmark and on a real dataset provided by the Italian company Elettric80. The obtained results show that the proposed method succeeds in determining in a short computational time both feasible routes and loading plans, minimizing the related costs while fulfilling logistics constraints
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