Colored Petri Net Model Research Articles

Access Control Verification in Smart Contracts Using Colored Petri Nets

This paper presents an approach for the verification of access control in smart contracts written in the Digital Asset Modeling Language (DAML). The approach utilizes Colored Petri Nets (CPNs) and their analysis tool CPN Tools. It is a model-driven-based approach that employs a new meta-model for capturing access control requirements in DAML contracts. The approach is supported by a suite of tools that fully automates all of the steps: parsing DAML code, generating DAML model instances, transforming the DAML models into CPN models, and model checking the generated CPN models. The approach is tested using several DAML scripts involving access control extracted from different domains of blockchain applications.

Increasing airspace capacity by improving ATCo’s efficiency through an innovative handover mechanism

The current lack of airspace capacity poses a major challenge to a sustainable and efficient air transport system, especially as future demand increases. Recent efforts to increase airspace capacity have focused on airspace sectorization. The digitization of Air Traffic Management (ATM) holds promise for overcoming current inefficiencies arising from the spatial fragmentation of airspace. While research has explored digitized ATM services to improve airspace capacity, there has been a notable gap in addressing spare capacity through enhancing synergies between adjacent sectors. This work proposes the application of an early handover (EHO) mechanism based on the spatio-temporal interdependencies among sectors and aircraft. Essentially, the mechanism involves alleviating overloaded sectors by redistributing peak demand to neighboring ones. This alleviation results in a reduction of the dedicated resources required to meet demand, facilitating the consolidation of sectors into larger units. Ultimately, this consolidation enhances airspace efficiency by minimizing the ATCo resources necessary for ATM. A simple and fast heuristic is proposed to select the aircraft for early handover to the air traffic controller of another sector, together with a specific schedule. A Colored Petri Net model is implemented to formalize the dynamic spatio-temporal interdependencies among adjacent sectors and to illustrate the EHO applicability using an academic exercise for illustration purposes. Afterwards, a simulation study based on real European airspace data is employed to illustrate and validate the mechanism. Finally, a discussion on the potential impacts of adopting the mechanism in real-life applications and lines of future research are provided.

Research on the Smart Broad Bean Harvesting System and the Self-Adaptive Control Method Based on CPS Technologies

With the rapid development of new-generation cyber–physical system (CPS) technologies, the smart operation and management of the broad bean harvesting system are enabled. This paper proposed a smart broad bean harvesting system (SBHS) and a self-adaptive control method based on CPS technologies. Firstly, the overall architecture of the SBHS is designed, which consists of four main components, namely optimal intelligent perception environment configuration, digital twin model construction, virtual simulation and real-time optimization, self-adaptive adjustment and control. Then, three key enabling technologies are discussed in detail, namely, intelligent perception environment configuration for the SBHS, digital twin model construction for the SBHS, colored Petri net (CPN)-based self-adaptive analysis and control of the harvesting system. Lastly, a proof-of-concept experiment based on a cooperative company is presented to illustrate the main work logic and advantage of the proposed SBHS. After the edge–cloud cooperative intelligent harvesting environment is configured, the CPN model for the workflow of the SBHS is created to analyze and optimize the harvesting processes. In addition, a management and control platform are developed to further illustrate the implementation of the proposed SBHS and the self-adaptive control method.

Formal Security Analysis of ISA100.11a Standard Protocol Based on Colored Petri Net Tool

This paper presents a formal security analysis of the ISA100.11a standard protocol using the Colored Petri Net (CPN) modeling approach. Firstly, we establish a security threat model for the ISA100.11a protocol and provide a detailed description and analysis of the identified security threats. Secondly, we use the CPN tool to model the protocol formally and conduct model checking and security analysis. Finally, we analyze and discuss the results of the model checking, which demonstrate that the ISA100.11a standard protocol may have vulnerabilities when certain security threats exist, and provide some suggestions to enhance the security of the protocol. This research provides a certain level of security assurance for the ISA100.11a standard protocol and serves as a reference for similar security research on protocols.

Fluent Restoration Modelling Applied to a Real Power System Using Colored Petri Nets

In this article the Colored Petri Nets (CPN) and the Critical Path Method along with the Program Evaluation Review Technique (CPM/PERT) are described and their characteristics compared for application on the real-time fluent restoration of power systems. A CPN based method is proposed and has been found more suitable since it is able to represent the temporal sequencing and the logical dependency between restoration activities. The restoration planning of electrical power systems are based on a worksheet drawn up by experts, which contains a list of procedures for restoration. The restoration process has been improved and a real case study is presented using the CPN modeling applied with success to an operative fluent restoration post-outage in the Brazilian interconnected system

Colored Petri Nets for Modeling and Simulation of a Green Supply Chain System

Green supply chain is an emerging approach in supply chain management to reduce environmental impact of the process concerning the flow of goods and materials. As a discrete-event system, supply chain can be modeled using Petri Nets. Colored Petri Nets (CPNs) extend the classical Petri net formalism with data, time and hierarchy. These extensions makes it possible to deal with the green aspects of the supply chain.This paper deals with the Colored Petri Net approach to model and simulate a green supply chain system. The forward supply chain network starts from the raw material suppliers, to the manufacturers, wholesalers, retailers and to the final customers. The reverse supply chain network is made of collecting points, recycling plants, disassembly plants, and secondary material market. A government environment agency plays the role of regulation of the recycling process. A colored Petri net model of the green supply chain is developed and simulated with CPN Tools, a dedicated software for CPN models. The simulation results as well as the state-space analysis results validate the correctness of the model.

Verification of cryptocurrency consensus protocols: reenterable colored Petri net model design

The reliability of consensus protocols establishes the basis for cryptocurrency cybersecurity. Formal and simulation techniques are appreciated for the verification of proof-of-work agreement protocols, because the formal techniques development process frequently requires a series of assumptions, leading to somewhat unrealistic models. A conventional colored Petri net model, presented by the authors in a previous study, allowed us to refine the Keller and Böhme consensus protocol by applying the simulation technique. In this study, we developed a reenterable colored Petri net model representing a general construct for model-driven development and refinement of consensus protocols and the corresponding software. A considerable benefit of a reenterable model is the invariance of its structure with respect to the net topology, number of attached nodes, and parameters of their software and hardware, which are represented as the marking of dedicated places. Switching of topology tags associated with dynamic objects represents the basic principle of reenterable model functioning. It is shown that, having the same characteristics, in bounds of admissible error of some 2-3%, the reenterable model results in 6 times speed-up of the simulation process and a drastic decrease in time for model editing, especially when the number of nodes exceeds a hundred. Thus, a reenterable model is a valuable complement to possible formal models that allows us to obtain express-evaluations of characteristics in a rather short time and with an acceptable level of adequacy.

Modelling, simulation and performance evaluation of the IEEE 802.11e protocol with station mobility.

In this article, we present a parameterized Colored Petri Net (CPN) model of the IEEE 802.11e protocol for wireless communications with mobile stations. CPNs provide a graphical model for the modeling and analysis of concurrent systems, which can be parameterized by the use of constants, and thus they allow us to create more flexible models. Our CPN model captures the protocol's behavior, and the specific parameters used for the 802.11e protocol and the scenarios to be evaluated are captured by the CPN parameters. The model presented is flexible enough to cover full customization of traffic types, user mobility and collision avoidance protocols. In this model, there is an access point (AP) which is visible to all the stations, and we assume that due to physical restrictions, there are two range groups. All the stations in the same range group are visible to each other. The impact of mobility is then analyzed by studying a situation in which the stations move in a controlled way to the same range group. The simulation results demonstrate the impact on network performance for sensitive and insensitive traffic types, as well as the role of the RTS/CTS protocol in collision avoidance, especially when users are located in different regions. Specifically, we show how the performance improves in the different scenarios when the stations move to the same area, where they can see each other, and we also study the impact on the performance for each type of traffic.

Coverage visualization and analysis of net inscriptions in coloured Petri net models

High-level Petri nets such as coloured Petri nets (CPNs) are characterized by the combination of Petri nets and a high-level programming language. In CPNs and CPN Tools, the inscriptions (e.g. arc expressions and guards) are specified using Standard ML. The application of simulation and state space exploration for validating CPN models traditionally focuses on behavioural properties related to net structure, i.e. places and transitions. This means that the net inscriptions are only implicitly validated, and the extent to which their sub-expressions have been covered is not made explicit. This paper extends our previous work on coverage analysis of net inscriptions of CPN models. In particular, we improve the CPN Tools library responsible for annotating, instrumenting and collecting the evaluation of Boolean conditions for determining the coverage criteria based on model executions. The library now automates most of the instrumentation parts that were done manually before and integrates the reports of the coverage analysis into the CPN Tools GUI. We evaluate our approach on new publicly available CPN models.

Social Robots Privacy Enhancement Using Colored Petri Net (CPN) for Behavior Modeling: A Case Study of Asus Zenbo Robot

The interactions between a social robot and the user consist of continuous communication and behavior involving different data types that can be subject to cybersecurity attacks and prone to user privacy concerns. In this paper, we use Colored Petri Net (CPN) to develop two graphical models that illustrate different patterned behavior of a robot during such interaction. Using CPN, we model and analyze complicated robot system interactions considering synchronization and concurrency of events that can be subject to privacy violations. We focus on two specific scenarios involving user registration and medication reminder to provide an efficient illustration of the objects and events collaborated to carry out the intended tasks of the robot pertaining to privacy issues. The results show that CPN modeling simulation can capture and represent the robot's behavior, provide a better understanding of the task execution, and highlight users' privacy gaps requiring immediate controls.

Modeling and analysis of traffic warning message dissemination system in VANETs

As the preferred underpinning technology of intelligent transportation systems (ITS), vehicular ad hoc networks (VANETs) have been widely used to cope with various traffic problems. However, implementing application-specific message dissemination in VANETs with fewer message dissemination is a challenge since, in fact, it is not meaningful for some vehicles to get such a message for the application requirements for alleviating traffic congestion. Thus, this paper proposes a traffic warning message dissemination system (TWMDS) framework together with a protocol for traffic warning messages (TWMs) dissemination called the reverse routing protocol (RRP). With TWMDS, when an abnormal traffic event (ATE) occurs, the vehicle causing this event generates a standardized TWM. This message is then forwarded only to the vehicles that may enter the potential congestion area (PCA) via vehicle-to-vehicle and vehicle-to-intersection interactions. In addition, three colored petri net models are developed to model and analyze the interaction behavior of TWMDS. In this way, we show the correctness and reliability of RRP and provide a feasibility measure for the subsequent development and implementation of TWMDS. Finally, we use Veins framework integrating OMNeT++ and SUMO to simulate the TWMDS functional modules, which further validates that RRP has a higher application value compared with three other routing protocols in TWMDS. With TWMDS, drivers can re-route their traveling paths as soon as possible to alleviate traffic congestion.

Simulation Based Analysis of Hierarchical Timed Colored Petri Nets Model of the Restaurant Food Serving Process

The major goal of establishing a restaurant is improved earnings making which can be jeopardized by customers' withdrawals due to lengthy ready lines. The above scenario was studied in this paper using simulation-based analysis of a Hierarchical Timed Coloured Petri Nets (HTCPN) model, which abstracted the serving operation of a renowned restaurant in the Ibadan metropolis. The restaurant was characterized by two or more servers that serially served each Customer from the multiple available servers at the four serving points. One hundred simulation runs were carried out on the HTCPN model using CPN Tools to determine the four (4) parameters,Customers' Average Flow Time (CAFT),Customers' Average Waiting Time (CAWT),Servers' Average Utilization Rate (SAUR) andCustomers' Average Queue Length (CAQL) required in serving 567, 1100, 1103, 770 and 829 customers from Monday to Friday, respectively. The model was validated by carrying out a statistical analysis t-Test between the simulated and the actual customers' flow time andservers' utilization rate at a 5% significant level. The validation results showed no significant differences between the simulated and the actual customers' average flow time andservers' utilization rate at a 5% significance level. Hence, the model can represent the restaurant under consideration.

Ant colony optimisation of a community pharmacy dispensing process using Coloured Petri-Net simulation and UK pharmacy in-field data

There are 11,619 community pharmacies in England which dispense over 1 billion prescriptions each year, providing essential primary care to NHS (National Health Service) patients. These pharmacies are facing pressure from a number of sources including funding cuts and high demands on services, while trying to deliver the highest standards of care. This paper presents an optimisation of a Coloured Petri Net (CPN) community pharmacy simulation model using an Ant Colony Optimisation (ACO) method. The CPN method was proposed by Naybour et al . Quantitative data from UK community pharmacies was collected by the authors and incorporated into the CPN simulation model. The optimisation is made up of a choice of how many staff to employ, which prescription checking strategy to use, and which staff work pattern to implement. This method aims to provide decision makers with a set of optimal pharmacy configurations at different cost levels. This can help to support pharmacy safety, efficiency, and improve decision making processes. It has been demonstrated how reliability modelling techniques traditionally used in safety-critical industries, can be used to carry out safety and efficiency analyses of healthcare systems, such as dispensing processes in community pharmacies, illustrated in this contribution.

Modeling and Analyzing of Breast Tumor Deterioration Process with Petri Nets and Logistic Regression

It is important to understand the process of cancer cell metastasis and some cancer characteristics that increase disease risk. Because the occurrence of the disease is caused by many factors, and the pathogenesis process is also complicated. It is necessary to use interpretable and visual modeling methods to characterize this complex process. Machine learning techniques have demonstrated extraordinary capabilities in identifying models and extracting patterns from data to improve medical prognostic decisions. However, in most cases, it is unexplainable. Using formal methods to model can ensure the correctness and understandability of prediction decisions in a certain extent, and can well visualize the analysis process. Coloured Petri Nets (CPN) is a powerful formal model. This paper presents a modeling approach with CPN and machine learning in breast cancer, which can visualize the process of cancer cell metastasis and the impact of cell characteristics on the risk of disease. By evaluating the performance of several common machine learning algorithms, we finally choose the logistic regression algorithm to analyze the data, and integrate the obtained prediction model into the CPN model. Our method allows us to understand the relations among the cancer cell metastasis and clearly see the quantitative prediction results.

Qualitative and Quantitative Safety Evaluation of Train Control Systems (CTCS) With Stochastic Colored Petri Nets

Currently qualitative as well as quantitative safety analysis of railway systems are usually conducted through Fault Tree Analysis (FTA) and Event Tree Analysis (ETA). FTA and ETA display the causalities and consequences of hazards or accidents by means of linear event sequences, which makes it difficult to incorporate non-linear relationships such as feedback. The repair of failure system components is not considered in traditional FTA and ETA. Moreover, quantitative safety evaluation by FTA and ETA requires that failure events should be statistically independent. Considering these issues, we propose an approach of conducting qualitative as well as quantitative safety evaluation of the CTCS-3 with stochastic Coloured Petri Nets (CPNs). The hierarchical CPN model of the CTCS-3 takes the scenarios, movement of trains, the failure and repair of system components into account. The occurrence times of hazardous events of a CTCS-3 system is quantitatively evaluated with the numerical data collected during the simulation of the system model. The evaluation results demonstrate the feasibility of the proposed approach.

Towards a Full Model-Driven Approach for Modeling and Verifying Business Process Models Using CPN

This work addresses one of the core issues in modern enterprises applications: Business Process (BP), by proposing a new comprehensive model-driven approach for automated and formal verification of BP models. This allows BP specialists to formally and automatically verify their process models, without needing a deep knowledge of formal methods. The approach automatically converts BP models to Colored Petri Nets (CPNs) using CPN Tools for the analysis purposes. It starts with meta-modeling formalisms of BP and CPNs using Atom3 Tool. At this level, it proposes two graph grammars. The former converts BP models into their corresponding CPNs and the latter interprets the acquired CPN models in a text format based on XML. This enables model transfer from Atom3 to CPN tools by assessing the correctness of the BP model. In order to test the functional utility of our proposed approach, we applied it to several examples and the results showed that the system is working correctly and that inconsistencies are detected in BP models. One detailed example is given to illustrate our approach.

Translation validation of coloured Petri net models of programs on integers

Translation validation of coloured Petri net models of programs on integers

Towards a formal modelling, analysis and verification of a clone node attack detection scheme in the internet of things

A clone node attack is one of the severe attacks on the Internet of Things (IoT) network. In a clone node attack, an adversary aims to physically capture the secret credentials of the deployed IoT devices to make the clone of devices look similar to the original devices. In recent years, several solutions for detecting clone node attacks have been designed; however, the focus of such designed solutions is on system design discussion, specific feature sets, high-level abstraction of underlying system architecture and fulfilling the performance analysis requirements. While the designed solutions efficiently detect clone attacks, critical features such as modelling, analysis, and verification of such solutions are frequently overlooked, necessitating that users verify their internal behaviour and claimed properties to ensure that no problematic scenarios or anomalies exist. Taking into account the rationale for formal verification and the limitations of previous works, this paper aims to perform formal modelling, analysis, and verification of our existing proposed clone node attack detection scheme for IoT. We used the High-Level Petri Nets (HLPNs) and Z-specification language to model our proposed scheme and analyse the logic correctness of our scheme using incidence markings and confidence interval matrices. To validate the functional correctness, we utilised the Satisfiability Modulo Theories Library (SMT-Lib) and the Z3 Solver and verified the functional satisfiable properties by analysing sat/unsat verification results and their execution time. Finally, we extend our modelling work by utilising the Coloured Petri Nets (CPNs), taking into consideration their both timed and untimed models with the aim of validating functional correctness and logical correctness, respectively. To analyse both correctnesses of CPN models, we used logging facility statistics such as count, sum, average, minimum, and maximum as data packet observations.

A Colored Petri Net Executable Modeling Approach for a Data Flow Well-Structured BPMN Process Model

A Colored Petri Net Executable Modeling Approach for a Data Flow Well-Structured BPMN Process Model

A TCPN-based model for testing distributed systems with timing constraints

This paper focuses on extending the basis of distributed test to address the testing process for time-sensitive distributed systems. In this context, we present an alternative approach to manage the problems that occur in this area, commonly referred to as controllability, observability and synchronisation issues. The key point of the proposed study is to define the activities of each tester through a set of timed distributed testing rules. Thus, we present our algorithm for the generation of such rules. Each rule is handled as a data structure comprising the data to be sent or received, the guard to be controlled and the set of clocks to be updated at the end of each transition. Afterwards, we show how we can use a timed coloured Petri nets model to cope with the complex tasks of testers' monitoring in the distributed test context. The simulation results revealed the effectiveness of our approach in providing correct execution of the system actions but also show how the response time of each tester can be improved by considering the temporal constraints. Indeed, the test becomes non-blocking and stops immediately by returning a false verdict if the temporal constraints have not been met.