ALESSANDRO FANTECHI - Academia.edu (original) (raw)

Papers by ALESSANDRO FANTECHI

Springer eBooks, Jul 27, 2009

NASA Formal Methods Symposium, Apr 1, 2009

La pubblicazione è resa disponibile sotto le norme e i termini della licenza di deposito, secondo... more La pubblicazione è resa disponibile sotto le norme e i termini della licenza di deposito, secondo quanto stabilito dalla Policy per l'accesso aperto dell'Università degli Studi di Firenze (https://www.sba.unifi.it/upload/policy-oa-2016-1.pdf)

Formal methods are increasingly used to validate the design of software and hardware components o... more Formal methods are increasingly used to validate the design of software and hardware components of safety critical systems. We describe here a case study where a formal verification method was applied in practice. As a case study we have considered a safe interaction policy between communicating objects, the Multiple Levels of Integrity policy. This policy can be seen as a communication protocol that guarantees the integrity of sensible data. Formal specification is given using a process algebra, and validation is done following a model checking approach. EMAIL:: gnesi@iei.pi.cnr.it

Variability Modelling of Software-Intensive Systems, 2010

We discuss the application of deontic logics to the modelling of variabilities in product family ... more We discuss the application of deontic logics to the modelling of variabilities in product family descriptions. Deontic logics make it possible to express concepts like permission and obligation, and hence promise a direct modelling of constraints over the products of a family. Indeed, we first show how feature models can be straightforwardly characterised by means of a deontic logic. We then study the deontic modelling of the behavioural variability in product families by defining a deontic extension of a behavioural logic. This allows both constraints over the products of a family and constraints over their behaviour to be expressed in a single framework: a novelty in the field. We discuss how model-checking tools could support formal verification in this framework, and we indicate some future research into that direction.

Lecture Notes in Computer Science

2022 6th International Conference on System Reliability and Safety (ICSRS)

Reliability of complex Cyber-Physical Systems is necessary to guarantee availability and/or safet... more Reliability of complex Cyber-Physical Systems is necessary to guarantee availability and/or safety of the provided services. Diverse and complex fault tolerance policies are adopted to enhance reliability, that include a varied mix of redundancy and dynamic reconfiguration to address hardware reliability, as well as specific software reliability techniques like diversity or software rejuvenation. These complex policies call for flexible runtime health checks of system executions that go beyond conventional runtime monitoring of pre-programmed health conditions, also in order to minimize maintenance costs. Defining a suitable monitoring model in the application of this method in complex systems is still a challenge. In this paper we propose a novel approach, Reliability Based Monitoring (RBM), for a flexible runtime monitoring of reliability in complex systems, that exploits a hierarchical reliability model periodically applied to runtime diagnostics data: this allows to dynamically plan maintenance activities aimed at prevent failures. As a proof of concept, we show how to apply RBM to a 2oo3 software system implementing different fault-tolerant policies.

Lecture Notes in Computer Science, 2022

 Users may download and print one copy of any publication from the public portal for the purpose... more  Users may download and print one copy of any publication from the public portal for the purpose of private study or research.  You may not further distribute the material or use it for any profit-making activity or commercial gain  You may freely distribute the URL identifying the publication in the public portal If you believe that this document breaches copyright please contact us providing details, and we will remove access to the work immediately and investigate your claim.

Zenodo (CERN European Organization for Nuclear Research), Oct 19, 2022

In the context of the Shift2Rail open call S2R-OC-IP2-01-2019, one of the two work streams of the... more In the context of the Shift2Rail open call S2R-OC-IP2-01-2019, one of the two work streams of the 4SECURail project (GA 881775) pursues the objective to corroborate how a clear, rigorous standard interface specification between signalling subsystems can be designed by applying an approach based on semi-formal and formal methods. The objective is addressed by developing a demonstrator case study of the application of formal methods to the specification of standard interfaces, aimed at consolidating the most suitable techniques for rigorous standard interface specification, as well as at supporting a Cost-Benefit Analysis to back this strategy with sound economic arguments. This paper discusses the main results of the project.

arXiv (Cornell University), Aug 25, 2022

Reliability of complex Cyber-Physical Systems is necessary to guarantee availability and/or safet... more Reliability of complex Cyber-Physical Systems is necessary to guarantee availability and/or safety of the provided services. Diverse and complex fault tolerance policies are adopted to enhance reliability, that include a varied mix of redundancy and dynamic reconfiguration to address hardware reliability, as well as specific software reliability techniques like diversity or software rejuvenation. These complex policies call for flexible runtime health checks of system executions that go beyond conventional runtime monitoring of pre-programmed health conditions, also in order to minimize maintenance costs. Defining a suitable monitoring model in the application of this method in complex systems is still a challenge. In this paper we propose a novel approach, Reliability Based Monitoring (RBM), for a flexible runtime monitoring of reliability in complex systems, that exploits a hierarchical reliability model periodically applied to runtime diagnostics data: this allows to dynamically plan maintenance activities aimed at prevent failures. As a proof of concept, we show how to apply RBM to a 2oo3 software system implementing different fault-tolerant policies.

2019 IEEE 5th International forum on Research and Technology for Society and Industry (RTSI)

Reliability is a fundamental attribute of industrial systems and can be analytically computed usi... more Reliability is a fundamental attribute of industrial systems and can be analytically computed using reliability models. Industrial systems are nowadays complex systems, i.e. they are characterized by a large number of components. This characteristic generally makes the analytical analysis unfeasible. Generally, reliability is expressed, under the assumption of constant failure rate, through the Mean Time Between Failures (MTBF). The reliability analysis performed using the MTBF is generally accurate for time intervals close to the commissioning and to the end-of-life but tends to be inaccurate otherwise. We propose a novel bottom-up layered approach to obtain the reliability curve. The first layer is realized with Stochastic Time Petri Nets (STPNs), the second one with Reliability Block Diagrams (RBDs). This layered approach allows to improve the analysis of system reliability, thus improving maintenance plans and identifying and fixing design flaws.

Formal Aspects of Computing, 2021

The substitution of traditional occupancy detecting sensors with an Autonomous Positioning System... more The substitution of traditional occupancy detecting sensors with an Autonomous Positioning System (APS) is a promising solution to contain costs and improve performance of current tramway signalling systems. APS is an onboard system using satellite positioning and other inertial platforms to autonomously estimate the position of the tram with the needed levels of uncertainty and protection. However, autonomous positioning introduces, even in absence of faults, a quantitative uncertainty with respect to traditional sensors. This paper investigates this issue in the context of an industrial project: a model of the envisaged solution is proposed, and it is analysed using Uppaal Statistical Model Checker. A novel model-driven hazard analysis approach to the exploration of emerging hazards is proposed. The analysis emphasises how the virtualisation of legacy track circuits and on-board satellite positioning equipment may give rise to new hazards, not present in the traditional system.

Reliability, Safety, and Security of Railway Systems. Modelling, Analysis, Verification, and Certification, 2019

Formal methods and tools have been widely applied to the development of railway systems during th... more Formal methods and tools have been widely applied to the development of railway systems during the last decades. However, no universally accepted formal framework has emerged, and railway companies wishing to introduce formal methods have little guidance for the selection of the most appropriate methods and tools to adopt. A work package (WP) of the European project ASTRail, funded under the Shift2Rail initiative, addresses this problem, by performing a survey that considers scientific literature, international projects, and practitioners' perspectives to identify a collection of formal methods and tools to be applied in railways. This paper summarises the current results of this WP. We surveyed 114 scientific publications, 44 practitioners, and 8 projects to come to a shortlist of 14 methods considered suitable for system modelling and verification in railways. The methods and tools were reviewed according to a set of functional, language-related, and quality features. The current paper extends the body of knowledge with a set of publicly available documents that can be leveraged by companies for guidance on formal methods selection in railway system development.

Proceedings of the ACM/IEEE 42nd International Conference on Software Engineering, 2020

Formal methods and tools have a long history of successful applications in the design of safety-c... more Formal methods and tools have a long history of successful applications in the design of safety-critical railway products. However, most of the experiences focused on the application of a single method at once, and little work has been performed to compare the applicability of the dierent available frameworks to the railway context. As a result, companies willing to introduce formal methods in their development process have little guidance on the selection of tools that could t their needs. To address this goal, this paper presents a comparison between 9 dierent formal tools, namely Atelier B, CADP, FDR4, NuSMV, ProB, Simulink, SPIN, UMC, and UPPAAL SMC. We performed a judgment study, involving 17 experts with experience in formal methods applied to railways. In the study, part of the experts were required to model a railway signaling problem (a moving-block train distancing system) with the dierent tools, and to provide feedback on their experience. The information produced was then synthesized, and the results were validated by the remaining experts. Based on the outcome of this process, we provide a synthesis that describes when to use a certain tool, and what are the problems that may be faced by modelers. Our experience shows that the dierent tools serve dierent purposes, and multiple formal methods are required to fully cover the needs of the railway system design process. CCS CONCEPTS • General and reference → Empirical studies; • Software and its engineering → Formal methods; System modeling languages.

Leveraging Applications of Formal Methods, Verification and Validation: Verification Principles, 2020

Reliability, Safety, and Security of Railway Systems. Modelling, Analysis, Verification, and Certification, 2019

One promising option to improve performance and contain costs of current tramway signalling syste... more One promising option to improve performance and contain costs of current tramway signalling systems is to introduce an Autonomous Positioning System (APS) in substitution of traditional occupancy detecting sensors. APS is an onboard system that uses a plurality of sensors (such as GPS or inertial platform) and a Sensor Fusion Algorithm (SFA) to autonomously estimate the position of the tram with the needed levels of uncertainty and protection. Autonomous positioning however introduces, even in absence of faults, a quantitative uncertainty with respect to traditional sensors. This paper investigates this issue in the context of an industrial project: a model of the envisaged solution is adopted, and the Uppaal Statistical Model Checker is used to study possible hazards induced by the substitution of legacy track circuits with on-board satellite positioning equipment.

Lecture Notes in Computer Science, 2016

A smart transportation system can be seen as an aggregate of transportation opportunities and ser... more A smart transportation system can be seen as an aggregate of transportation opportunities and services, accompanied by advanced management services that make the access to the system easier for the user. In this paper, we exploit the product line paradigm to address the variability of an exemplary smart transportation system: a bike-sharing system. Improving the satisfaction of a user of a bike-sharing system includes providing information at runtime on the filling degree of the docking stations in the near future. To fulfill this expectation, a prediction service is needed to infer the probability that at a certain time of the day a user will return a bike to or take one from a station. In earlier studies, several possible advanced smart predictive services were identified. The choice of which services to offer to users by the managers of a bike-sharing system is influenced by minimizing the costs while maximizing customer satisfaction. To aid the managers, we modeled a family of smart bike-sharing services, after which an attributed feature model was used to augment the model with quantitative attributes related to cost and customer satisfaction, allowing for a multi-objective optimization by dedicated tools. We observe that the performance of the smart prediction services, and therefore of the related customer satisfaction, is highly dependent on the amount of collected historical data on which the predictive analysis is based. Therefore the result of the optimization also depends on this factor, which evolves over time.

From Action Systems to Distributed Systems, 2016

Telecommunication Systems, 2017

Significant research efforts for the convergence of Web and Telecommunication services have been ... more Significant research efforts for the convergence of Web and Telecommunication services have been recently spent by research and industry stakeholders. The IETF and W3C are cooperating in specifying how web browsers should evolve to natively support communication services. In this perspective, devising novel mechanisms for signaling message exchange and possible interworking between Web-and SIP-based systems is a hot topic of research. Indeed, discussions are still ongoing on how differences between REpresentational State Transfer (REST) and Session Initiation Protocol (SIP) models should be coped with. This issue is made more difficult by the lack of rigorous modeling of RESTful systems. In this paper we propose a rigorous approach for design and implementation of REST communication services (e.g., a call service) which leverages formal verification techniques, while allowing to meet a specific performance requirement (i.e., maximum call setup delay). First, we formalize the call resource behavior through a Finite State Machine representation by modeling and simulating service expected behavior

… of FORMS 2003 …, 2003

... 21, Firenze, Italy, I-50127 Phone: +39 (055) 4234340, Fax: +39 (055) 4361110 E-mail: {stefano... more ... 21, Firenze, Italy, I-50127 Phone: +39 (055) 4234340, Fax: +39 (055) 4361110 E-mail: {stefano.bacherini, simone.bianchi, leonardo.capecchi ... The SCA system (Sistema Conta Assi,axel counter system), developed by General Electric Transportation Systems, GETS, is a device ...

 Users may download and print one copy of any publication from the public portal for the purpose... more  Users may download and print one copy of any publication from the public portal for the purpose of private study or research.  You may not further distribute the material or use it for any profit-making activity or commercial gain  You may freely distribute the URL identifying the publication in the public portal If you believe that this document breaches copyright please contact us providing details, and we will remove access to the work immediately and investigate your claim.

Springer eBooks, Jul 27, 2009

NASA Formal Methods Symposium, Apr 1, 2009

La pubblicazione è resa disponibile sotto le norme e i termini della licenza di deposito, secondo... more La pubblicazione è resa disponibile sotto le norme e i termini della licenza di deposito, secondo quanto stabilito dalla Policy per l'accesso aperto dell'Università degli Studi di Firenze (https://www.sba.unifi.it/upload/policy-oa-2016-1.pdf)

Formal methods are increasingly used to validate the design of software and hardware components o... more Formal methods are increasingly used to validate the design of software and hardware components of safety critical systems. We describe here a case study where a formal verification method was applied in practice. As a case study we have considered a safe interaction policy between communicating objects, the Multiple Levels of Integrity policy. This policy can be seen as a communication protocol that guarantees the integrity of sensible data. Formal specification is given using a process algebra, and validation is done following a model checking approach. EMAIL:: gnesi@iei.pi.cnr.it

Variability Modelling of Software-Intensive Systems, 2010

We discuss the application of deontic logics to the modelling of variabilities in product family ... more We discuss the application of deontic logics to the modelling of variabilities in product family descriptions. Deontic logics make it possible to express concepts like permission and obligation, and hence promise a direct modelling of constraints over the products of a family. Indeed, we first show how feature models can be straightforwardly characterised by means of a deontic logic. We then study the deontic modelling of the behavioural variability in product families by defining a deontic extension of a behavioural logic. This allows both constraints over the products of a family and constraints over their behaviour to be expressed in a single framework: a novelty in the field. We discuss how model-checking tools could support formal verification in this framework, and we indicate some future research into that direction.

Lecture Notes in Computer Science

2022 6th International Conference on System Reliability and Safety (ICSRS)

Reliability of complex Cyber-Physical Systems is necessary to guarantee availability and/or safet... more Reliability of complex Cyber-Physical Systems is necessary to guarantee availability and/or safety of the provided services. Diverse and complex fault tolerance policies are adopted to enhance reliability, that include a varied mix of redundancy and dynamic reconfiguration to address hardware reliability, as well as specific software reliability techniques like diversity or software rejuvenation. These complex policies call for flexible runtime health checks of system executions that go beyond conventional runtime monitoring of pre-programmed health conditions, also in order to minimize maintenance costs. Defining a suitable monitoring model in the application of this method in complex systems is still a challenge. In this paper we propose a novel approach, Reliability Based Monitoring (RBM), for a flexible runtime monitoring of reliability in complex systems, that exploits a hierarchical reliability model periodically applied to runtime diagnostics data: this allows to dynamically plan maintenance activities aimed at prevent failures. As a proof of concept, we show how to apply RBM to a 2oo3 software system implementing different fault-tolerant policies.

Lecture Notes in Computer Science, 2022

 Users may download and print one copy of any publication from the public portal for the purpose... more  Users may download and print one copy of any publication from the public portal for the purpose of private study or research.  You may not further distribute the material or use it for any profit-making activity or commercial gain  You may freely distribute the URL identifying the publication in the public portal If you believe that this document breaches copyright please contact us providing details, and we will remove access to the work immediately and investigate your claim.

Zenodo (CERN European Organization for Nuclear Research), Oct 19, 2022

In the context of the Shift2Rail open call S2R-OC-IP2-01-2019, one of the two work streams of the... more In the context of the Shift2Rail open call S2R-OC-IP2-01-2019, one of the two work streams of the 4SECURail project (GA 881775) pursues the objective to corroborate how a clear, rigorous standard interface specification between signalling subsystems can be designed by applying an approach based on semi-formal and formal methods. The objective is addressed by developing a demonstrator case study of the application of formal methods to the specification of standard interfaces, aimed at consolidating the most suitable techniques for rigorous standard interface specification, as well as at supporting a Cost-Benefit Analysis to back this strategy with sound economic arguments. This paper discusses the main results of the project.

arXiv (Cornell University), Aug 25, 2022

Reliability of complex Cyber-Physical Systems is necessary to guarantee availability and/or safet... more Reliability of complex Cyber-Physical Systems is necessary to guarantee availability and/or safety of the provided services. Diverse and complex fault tolerance policies are adopted to enhance reliability, that include a varied mix of redundancy and dynamic reconfiguration to address hardware reliability, as well as specific software reliability techniques like diversity or software rejuvenation. These complex policies call for flexible runtime health checks of system executions that go beyond conventional runtime monitoring of pre-programmed health conditions, also in order to minimize maintenance costs. Defining a suitable monitoring model in the application of this method in complex systems is still a challenge. In this paper we propose a novel approach, Reliability Based Monitoring (RBM), for a flexible runtime monitoring of reliability in complex systems, that exploits a hierarchical reliability model periodically applied to runtime diagnostics data: this allows to dynamically plan maintenance activities aimed at prevent failures. As a proof of concept, we show how to apply RBM to a 2oo3 software system implementing different fault-tolerant policies.

2019 IEEE 5th International forum on Research and Technology for Society and Industry (RTSI)

Reliability is a fundamental attribute of industrial systems and can be analytically computed usi... more Reliability is a fundamental attribute of industrial systems and can be analytically computed using reliability models. Industrial systems are nowadays complex systems, i.e. they are characterized by a large number of components. This characteristic generally makes the analytical analysis unfeasible. Generally, reliability is expressed, under the assumption of constant failure rate, through the Mean Time Between Failures (MTBF). The reliability analysis performed using the MTBF is generally accurate for time intervals close to the commissioning and to the end-of-life but tends to be inaccurate otherwise. We propose a novel bottom-up layered approach to obtain the reliability curve. The first layer is realized with Stochastic Time Petri Nets (STPNs), the second one with Reliability Block Diagrams (RBDs). This layered approach allows to improve the analysis of system reliability, thus improving maintenance plans and identifying and fixing design flaws.

Formal Aspects of Computing, 2021

The substitution of traditional occupancy detecting sensors with an Autonomous Positioning System... more The substitution of traditional occupancy detecting sensors with an Autonomous Positioning System (APS) is a promising solution to contain costs and improve performance of current tramway signalling systems. APS is an onboard system using satellite positioning and other inertial platforms to autonomously estimate the position of the tram with the needed levels of uncertainty and protection. However, autonomous positioning introduces, even in absence of faults, a quantitative uncertainty with respect to traditional sensors. This paper investigates this issue in the context of an industrial project: a model of the envisaged solution is proposed, and it is analysed using Uppaal Statistical Model Checker. A novel model-driven hazard analysis approach to the exploration of emerging hazards is proposed. The analysis emphasises how the virtualisation of legacy track circuits and on-board satellite positioning equipment may give rise to new hazards, not present in the traditional system.

Reliability, Safety, and Security of Railway Systems. Modelling, Analysis, Verification, and Certification, 2019

Formal methods and tools have been widely applied to the development of railway systems during th... more Formal methods and tools have been widely applied to the development of railway systems during the last decades. However, no universally accepted formal framework has emerged, and railway companies wishing to introduce formal methods have little guidance for the selection of the most appropriate methods and tools to adopt. A work package (WP) of the European project ASTRail, funded under the Shift2Rail initiative, addresses this problem, by performing a survey that considers scientific literature, international projects, and practitioners' perspectives to identify a collection of formal methods and tools to be applied in railways. This paper summarises the current results of this WP. We surveyed 114 scientific publications, 44 practitioners, and 8 projects to come to a shortlist of 14 methods considered suitable for system modelling and verification in railways. The methods and tools were reviewed according to a set of functional, language-related, and quality features. The current paper extends the body of knowledge with a set of publicly available documents that can be leveraged by companies for guidance on formal methods selection in railway system development.

Proceedings of the ACM/IEEE 42nd International Conference on Software Engineering, 2020

Formal methods and tools have a long history of successful applications in the design of safety-c... more Formal methods and tools have a long history of successful applications in the design of safety-critical railway products. However, most of the experiences focused on the application of a single method at once, and little work has been performed to compare the applicability of the dierent available frameworks to the railway context. As a result, companies willing to introduce formal methods in their development process have little guidance on the selection of tools that could t their needs. To address this goal, this paper presents a comparison between 9 dierent formal tools, namely Atelier B, CADP, FDR4, NuSMV, ProB, Simulink, SPIN, UMC, and UPPAAL SMC. We performed a judgment study, involving 17 experts with experience in formal methods applied to railways. In the study, part of the experts were required to model a railway signaling problem (a moving-block train distancing system) with the dierent tools, and to provide feedback on their experience. The information produced was then synthesized, and the results were validated by the remaining experts. Based on the outcome of this process, we provide a synthesis that describes when to use a certain tool, and what are the problems that may be faced by modelers. Our experience shows that the dierent tools serve dierent purposes, and multiple formal methods are required to fully cover the needs of the railway system design process. CCS CONCEPTS • General and reference → Empirical studies; • Software and its engineering → Formal methods; System modeling languages.

Leveraging Applications of Formal Methods, Verification and Validation: Verification Principles, 2020

Reliability, Safety, and Security of Railway Systems. Modelling, Analysis, Verification, and Certification, 2019

One promising option to improve performance and contain costs of current tramway signalling syste... more One promising option to improve performance and contain costs of current tramway signalling systems is to introduce an Autonomous Positioning System (APS) in substitution of traditional occupancy detecting sensors. APS is an onboard system that uses a plurality of sensors (such as GPS or inertial platform) and a Sensor Fusion Algorithm (SFA) to autonomously estimate the position of the tram with the needed levels of uncertainty and protection. Autonomous positioning however introduces, even in absence of faults, a quantitative uncertainty with respect to traditional sensors. This paper investigates this issue in the context of an industrial project: a model of the envisaged solution is adopted, and the Uppaal Statistical Model Checker is used to study possible hazards induced by the substitution of legacy track circuits with on-board satellite positioning equipment.

Lecture Notes in Computer Science, 2016

A smart transportation system can be seen as an aggregate of transportation opportunities and ser... more A smart transportation system can be seen as an aggregate of transportation opportunities and services, accompanied by advanced management services that make the access to the system easier for the user. In this paper, we exploit the product line paradigm to address the variability of an exemplary smart transportation system: a bike-sharing system. Improving the satisfaction of a user of a bike-sharing system includes providing information at runtime on the filling degree of the docking stations in the near future. To fulfill this expectation, a prediction service is needed to infer the probability that at a certain time of the day a user will return a bike to or take one from a station. In earlier studies, several possible advanced smart predictive services were identified. The choice of which services to offer to users by the managers of a bike-sharing system is influenced by minimizing the costs while maximizing customer satisfaction. To aid the managers, we modeled a family of smart bike-sharing services, after which an attributed feature model was used to augment the model with quantitative attributes related to cost and customer satisfaction, allowing for a multi-objective optimization by dedicated tools. We observe that the performance of the smart prediction services, and therefore of the related customer satisfaction, is highly dependent on the amount of collected historical data on which the predictive analysis is based. Therefore the result of the optimization also depends on this factor, which evolves over time.

From Action Systems to Distributed Systems, 2016

Telecommunication Systems, 2017

Significant research efforts for the convergence of Web and Telecommunication services have been ... more Significant research efforts for the convergence of Web and Telecommunication services have been recently spent by research and industry stakeholders. The IETF and W3C are cooperating in specifying how web browsers should evolve to natively support communication services. In this perspective, devising novel mechanisms for signaling message exchange and possible interworking between Web-and SIP-based systems is a hot topic of research. Indeed, discussions are still ongoing on how differences between REpresentational State Transfer (REST) and Session Initiation Protocol (SIP) models should be coped with. This issue is made more difficult by the lack of rigorous modeling of RESTful systems. In this paper we propose a rigorous approach for design and implementation of REST communication services (e.g., a call service) which leverages formal verification techniques, while allowing to meet a specific performance requirement (i.e., maximum call setup delay). First, we formalize the call resource behavior through a Finite State Machine representation by modeling and simulating service expected behavior

… of FORMS 2003 …, 2003

... 21, Firenze, Italy, I-50127 Phone: +39 (055) 4234340, Fax: +39 (055) 4361110 E-mail: {stefano... more ... 21, Firenze, Italy, I-50127 Phone: +39 (055) 4234340, Fax: +39 (055) 4361110 E-mail: {stefano.bacherini, simone.bianchi, leonardo.capecchi ... The SCA system (Sistema Conta Assi,axel counter system), developed by General Electric Transportation Systems, GETS, is a device ...

 Users may download and print one copy of any publication from the public portal for the purpose... more  Users may download and print one copy of any publication from the public portal for the purpose of private study or research.  You may not further distribute the material or use it for any profit-making activity or commercial gain  You may freely distribute the URL identifying the publication in the public portal If you believe that this document breaches copyright please contact us providing details, and we will remove access to the work immediately and investigate your claim.