Papers by Giorgio Iacobellis
This paper validates a Colored Timed Petri Net (CTPN) model proposed to describe urban traffic ne... more This paper validates a Colored Timed Petri Net (CTPN) model proposed to describe urban traffic networks. In particular, a CTPN models the dynamics of signalized traffic networks and timed Petri nets describe the traffic lights controlling the area. To this aim, the modeling framework is applied to a real intersection located in Bari, Italy. Discrete event simulations of the controlled intersection test the signal timing plan under different traffic scenarios and give a confirmation of the model capability to correctly predict the traffic performance.
IEEE Transactions Automation Science and Engineering, 2009
A Supply Chain (SC) is a network of independent manufacturing and logistics companies that perfor... more A Supply Chain (SC) is a network of independent manufacturing and logistics companies that perform the critical functions in the order fulfillment process. This paper proposes an effective and modular model to describe material, financial and information flow of SCs at the operational level based on first order hybrid Petri Nets (PNs), i.e., PNs that make use of first order fluid approximation. The proposed formalism enables the SC designer to choose suitable production rates of facilities in order to optimize the chosen objective function. The optimal mode of operation is performed based on the state knowledge of the obtained linear discrete-time, timevarying state variable model in order to react to unpredictable events such as the blocking of a supply or an accident in a transportation facility. A case study is modeled in the proposed framework and is simulated under three different closed loop control strategies that allow us to optimize appropriate performance indices. Note to Practitioners-The motivation of the present work is to provide a generic, simple and accurate model able to integrate material, financial and information flow description for use by decision makers in SC management at the operational level. To this aim, the paper proposes a model based on the first order hybrid PN formalism that provides the SC designers with important key features. First, the model exhibits good computational efficiency and easy implementation in engineering software packages. Second, some SC design parameters, such as the supplier and manufacturer production rates, are real continuous variables and can be determined by polynomial complexity optimization of suitable performance indices. Third, based on the knowledge of the system state and the information about the occurrence of typical operational 2 unpredictable events (e.g. facility blockings and goods demands), the model enables the decision makers to update some operational design parameters in a closed loop strategy.
While in the private sector the buyer chooses the number of potential suppliers to involve in an ... more While in the private sector the buyer chooses the number of potential suppliers to involve in an exchange, in the public sector the procedures to follow usually oblige the purchasing manager to behave in a different way. According to the European Directive 2004/18/EC, the Public Administration has to consider all the bids belonging to all the suppliers willing, and able, to take part into the trade. The main purpose of the law is to increase the competitiveness among several bidders in order to reduce the public spending, avoiding monopolistic or oligopolistic behaviours. However the legislator has not taken into account the costs associated with participation in the single tender. In the paper we underline that these costs are relevant and so by limiting the number of bidders it is possible to save money both for the Public Administration and the private sector.
This paper focuses on real time control of automated storage and retrieval systems (AS/RS) that i... more This paper focuses on real time control of automated storage and retrieval systems (AS/RS) that is in charge of making decisions on resource allocation and scheduling choices. In these systems deadlock conditions may occur when parts require a set of resources in a circular wait situation. We model a generic multi-product AS/RS serviced by rail guided vehicles as a discrete event system. Next, we compare two different real time deadlock solution strategies for AS/RS: a deadlock avoidance strategy previously proposed by one of the authors and a deadlock detection/recovery strategy, proposed in the related literature. The considered control strategies are compared by means of a simulation of a case study.
The paper specifies an Integrated System (IS) devoted to efficient management and control of Inte... more The paper specifies an Integrated System (IS) devoted to efficient management and control of Intermodal Transportation Networks (ITN). The IS is designed to take both tactical decisions, in an off-line mode, and operational decisions, in real time. Both the resulting IS structures rely on a closed loop approach tuning decisions with the current system conditions. In either case, the IS core is a reference model using information from the real system, obtained by modern Information and Communication Technologies (ICT) tools, for ITN efficient planning and management purposes. To obtain a systematic model suitable to describing generic ITN, the reference model relies on a metamodeling approach that allows the thorough and detailed description of the ITN structure and behavior. The proposed metamodeling procedure is a top-down approach based on the Unified Modeling Language, a graphic and textual formalism for representing systems structure and behavior.
Transaction costs analysis was first addressed by Coase in 1937 and is concerned with ways of ali... more Transaction costs analysis was first addressed by Coase in 1937 and is concerned with ways of aligning appropriate governance modes with the attributes of economic transactions. Nowadays transaction costs are universally accepted, but researchers in the field agree on the difficulty in measuring and quantifying them. Starting from the universally accepted definition of transaction costs, this paper proposes a model for the buyer/seller relationship, focusing on the uncertainty characterizing the exchange and the connected costs. In particular, according to a well-known classification, transaction costs are divided into ex ante (drafting and negotiating agreements) and ex post (monitoring and enforcing agreements) costs.
Abstract Fierce global competition, rapid market changes and short product life cycles originated... more Abstract Fierce global competition, rapid market changes and short product life cycles originated the diffusion of automated warehousing systems. This paper focuses on the performance evaluation and management of an Automated Distribution Center (ADC), ie, a specific and automated type of warehouse where storage of products is limited or non-existent and the core activity is the sorting operation. We consider a case study in the clothing factory and we model the ADC as a discrete event system by way of the UML ...
Transaction costs analysis is concerned with ways of aligning appropriate governance modes with t... more Transaction costs analysis is concerned with ways of aligning appropriate governance modes with the attributes of economic transactions. Nowadays transaction costs are universally accepted, despite the difficulty in measuring and quantifying them. Starting from the customary definition of transaction costs, this paper proposes a model for the buyer/seller relationship, focusing on the uncertainty characterizing the exchange and the connected costs. In particular, according to a well-known classification, the transaction costs connected to the purchasing phase are divided into ex ante (drafting and negotiating agreements) and ex post (monitoring and enforcing agreements) costs. More precisely, we propose to employ appropriate deterministic models for evaluating ex ante costs and suitable statistical distributions for ex post costs. Obviously, both such costs categories require the quantification of several parameters related to the buyer operating the transaction and to the uncertainty characterizing the buyer/seller relationship. Hence, in order to correctly evaluate the buyer behavior, a fuzzy logic inference system is designed for synthesizing, starting from expert judgments, the required data to the transaction costs model. The reported simulation experiments show the effectiveness of the proposed model in estimating the transaction costs and total costs associated with a generic transaction.
Journal of Business & Industrial Marketing, 2009
The paper proposes a Decision Support System (DSS) for selecting the suppliers that are candidate... more The paper proposes a Decision Support System (DSS) for selecting the suppliers that are candidate to join a supply chain network. The proposed DSS bases the decision on the cost evaluation of the transaction among the buyer and the available suppliers. In particular, the presented DSS includes a statistical module and the DSS core. The former module estimates the exchange performance indices, i.e. total cost of the transaction, purchasing price and additional costs of purchasing. The latter module implements the transaction evolution in an extended coloured Petri nets formalism, called flow coloured Petri nets, allowing a stochastic updating of the net marking via suitable queries to the first module. Several simulation tests demonstrate the ability of the proposed DSS in selecting the suppliers to be included in the supply chain.
The paper studies and assesses the application of an innovative solution based on Information and... more The paper studies and assesses the application of an innovative solution based on Information and Communication Technology (ICT) tools in managing security and customs clearance operations. In order to improve these procedures the paper analyzes the main anomalies and bottlenecks related to the customs clearance procedures and proposes novel ICT based solutions. In order to analyze the impact of the new procedures on the overall logistic system, a real case study is modelled and simulated.
IEEE Transactions Automation Science and Engineering, 2011
The paper specifies an Integrated System (IS) devoted to the management of Intermodal Transportat... more The paper specifies an Integrated System (IS) devoted to the management of Intermodal Transportation Networks (ITNs) to take both tactical decisions, i.e., in an offline mode, and operational decisions, i.e., in real-time. Both the resulting IS structures rely on a closed-loop approach that is able to tune the choices with the current system conditions. In either case, the core of the presented IS are a reference model and a simulation module. In particular, the reference model uses information from the real system, obtained by modern Information and Communication Technologies (ICTs) and the simulation module evaluates the impact of the management decisions. In order to obtain a systematic model suitable to describe a generic ITN, the paper proposes a metamodeling approach that describes in a thorough and detailed way the structure and the behavior of ITNs. Moreover, the metamodeling procedure is a top-down technique based on the well-known Unified Modeling Language (UML), a graphic and textual formalism able to describe systems from structural and behavioral viewpoints. In order to show the IS application at the tactical decision level, the paper specifies the IS for an ITN case study that is constituted by the port of Trieste (Italy) and the inland terminal of Gorizia (Italy). The results show how the IS can improve the performance of the ITN by applying ICT tools and information-based services.
This paper addresses the management and performance analysis of the pulmonology department of the... more This paper addresses the management and performance analysis of the pulmonology department of the general hospital of Bari, Italy, focusing on the department workflow and drug distribution system. To this aim, we present a discrete event system model which can be employed as a support for taking decisions regarding the information and automation integration in order to improve the drug procurement logistics and management. The model employs a timed Petri net framework to describe in a concise and detailed way the workflow in the pulmonology department, while considering various ordering and management policies of the department drug storehouse.
The paper proposes a metamodelling procedure devoted to provide a reference model to be used by d... more The paper proposes a metamodelling procedure devoted to provide a reference model to be used by decision makers in the performance evaluation of Intermodal Transportation Network (ITN). In order to obtain a generic model describing a nonspecific ITN from the structural and behavioural point of view, the metamodelling approach consists in applying a top down and modular procedure. The model is specified by the well known Unified Modelling Language (UML), a graphic and textual modelling formalism intended to describe systems from structural and dynamics viewpoints. Hence, the paper models a generic ITN starting from the network description and shows by a case study the metamodel of one of the most important nodes that compose it: the port subsystem. Moreover, the case study model is translated in a simulation software and the performance measures obtained by the simulation results are shown.
The paper proposes a model for real time control of urban traffic networks. A modular framework b... more The paper proposes a model for real time control of urban traffic networks. A modular framework based on first order hybrid Petri nets models the vehicle flows by a first order fluid approximation. Moreover, the lane interruptions and the signal timing plan controlling the area are described by the discrete event dynamics using timed Petri nets. The proposed model is applied to a real intersection located in Bari, Italy. Simulation of different scenarios shows the technique efficiency: validation is performed by comparison with a previously proposed alternative approach employing colored Petri nets.
The paper analyses a crucial problem in the international freight management and assesses the app... more The paper analyses a crucial problem in the international freight management and assesses the application of an innovative solution based on Information and Communication Technology (ICT) tools. In order to improve the customs clearance procedures, the paper analyses the main anomalies and bottlenecks related to international freight management of a case study by modelling the customs clearance activities in the Unified Modelling Language framework. Moreover, some novel ICT based solutions are proposed in order to optimize suited performance indices. The flow of goods and information involved in the case study is simulated in different scenarios in order to highlight the improvements reached by using ICT solutions. The simulation results point out the huge impact of ICT on customs clearance operations.
Abstract The paper proposes a model for real time control of freeways by ramp metering, an emergi... more Abstract The paper proposes a model for real time control of freeways by ramp metering, an emerging technique for efficient freeway management. A modular framework based on first order hybrid Petri nets models the vehicle flows by a first order fluid approximation. Moreover, the lane interruptions and the signal timing plan controlling on-ramps are described by the discrete event dynamics using timed Petri nets. The proposed formalism enables the network designer to choose suitable ramp metering control signals in order to ...
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Papers by Giorgio Iacobellis