Colored Petri Nets Research Articles

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.

Research on a Vehicle Authentication and Key Transmission Protocol Based on CPN

With the rapid development of the Internet of Vehicles, the increase in vehicle functional requirements has led to the continuous increase in complex electronic systems, and the in-vehicle network is extremely vulnerable to network attacks. The controller area network (CAN) bus is the most representative in-vehicle bus technology in intra-vehicular networks (IVNs) for its flexibility. Although the current framework to protect the safety of CAN has been proposed, the safety communication mechanism between electronic control units (ECUs) in the vehicle network is still weak. A large number of communication protocols focus on the addition of safety mechanisms, and there is a lack of general protocol formal modeling and security assessment. In addition, many protocols are designed without considering key updates and transmission, ECUs maintenance, etc. In this work, we propose an efficient in-vehicle authentication and key transmission scheme. This scheme is a certificateless framework based on identity cryptography, which can not only ensure the security of the in-vehicle network but also meet the real-time requirements between ECUs. Moreover, this scheme can reduce the complexity of key management for centralized key generators. To evaluate the security of this scheme, we adopt a protocol model detection method based on the combination of the colored Petri net (CPN) and the Dolev–Yao attack model to formally evaluate the proposed protocol. The evaluation results show that the proposed scheme can effectively prevent three types of man-in-the-middle attacks.

Skeleton Abstraction for Universal Temporal Properties

Uniform coloured Petri nets can be abstracted to their skeleton, the place/transition net that simply turns the coloured tokens into black tokens. A coloured net and its skeleton are related by a net morphism [1, 2]. For the application of the skeleton as an abstraction method in the model checking process, we need to establish a simulation relation [3] between the state spaces of the two nets. Then, universal temporal properties (properties of the ACTL* logic) are preserved. The abstraction relation induced by a net morphism is not necessarily a simulation relation, due to a subtle issue related to deadlocks [4]. We discuss several situations where the abstraction relation induced by a net morphism is as well a simulation relation, thus preserving ACTL* properties. We further propose a partition refinement algorithm for folding a place/transition net into a coloured net. This way, skeleton abstraction becomes available for models given as place/transition nets. Experiments demonstrate the capabilities of the proposed technology. Using skeleton abstraction, we are capable of solving problems that have not been solved before in the Model Checking Contest [5].

Edge Intelligence Service Orchestration with Process Mining

In the post-cloud computing era, edge computing as a distributed computing paradigm, integrating the core capabilities of computing, storage, network, and application, provides EIS (edge intelligence service), such as real-time business, data optimization, intelligent application, security, and privacy protection. The EIS has become the core value driver to promote the IoE (Internet of Everything), to dig deeply into data value and create a new ecology of application scenarios. With the emergence of new business processes, EIS orchestration has also become a hot topic in academic research. A design methodology based on a complete “describe-synthesize-verify-evaluate” process was established to explore executable design specifications for EIS by means of model validation and running instances. As proof of concept, a CPN (colored Petri net) prototype was simulated and its operational processes were discovered by process mining from event data available in EIS for behavior verification. The instances running on WISE-PaaS demonstrate the feasibility of the research methodology, which aims to optimize EIS through service orchestration.

A Formal Performance Evaluation Method for Customised Plug-and-Play Manufacturing Systems Using Coloured Petri Nets.

Recent technological advancements and the evolution of industrial manufacturing paradigms have substantially increased the complexity of product-specific production systems. To reduce the time cost of modelling and verification and to enhance the degree of uniformity in the modelling process of system components, this article presents a componentised framework for domain modelling and performance analysis based on the concept of “multi-granularity and multi-view” for a production line of personalised and customised products, for plug-and-play manufacturing processes to involving a large number of model input parameters. The coloured Petri net tool is utilised as a simulation tool for mapping domain models to computational models for simulation and performance evaluation. This paper presents a method for setting the input parameters of a production system when using WIP, through-put and cycle time as metrics. The results of the performance analysis demonstrate the applicability of the proposed framework and provide direction for the production line’s layout design and scheduling strategy.

High-Level Petri Nets-Based Modeling of Network Controlled Systems under Communication Constraints (Network-Induced Delay)

Our work deals with the problems of communication delays, packets dropouts, and quantization errors in the signal transmitted in network-controlled systems (NCS). Although NCS provides a paradigm for adapting to frequent changes in the manufacturing industry, modeling and managing operations are difficult issues due to the complex interactions between system entities and the effect of the network-induced delay on the closed-loop system. Therefore, our paper is about detecting degradations resulting from the insertion of a network in the regulation loop, which can even lead in some cases to the destabilization of the NCS. This paper mainly studies the problem of the graphic modeling, based on the colored Petri nets (CPN), of the NCS under communication constraints. Therefore, models of the communication network (Ethernet) and system entities are presented. Then, the influence of network-induced delay is detected. Finally, as an idea for future work, we propose a solution based on an SDN controller in order to avoid precedent degradations.

Coloured Petri Nets for Temporal Performance Evaluation of Distributed Control Systems—Application to a FIFO Queue

Temporal performances (like response time) of distributed control systems must be measurable for critical systems. The delay and reliability requirements require us to develop an exhaustive method to evaluate these performances through the most accurate models, such as (max,+) algebra combined with timed event graphs. Among the common mechanisms encountered in a distributed control system, the FIFO policy remains one of the most used and cannot be modeled with timed event graphs. We show that the formalism of timed coloured Petri nets described in the (max,+) algebra can model the FIFO queue of a Programmable Logic Controller communication module. We also aim to reveal some exciting features of coloured Petri nets when analytically evaluating temporal performances. We present, therefore, a Timed Coloured Petri net modeling the emptying of a FIFO queue with a periodic task, and the formulas of delays associated with the induced system of (max, +) equations. We also test the consistency of our bounds in a numerical application of our model with positive results.

The energy management and economic optimization scheduling of microgrid based on Colored Petri net and Quantum-PSO algorithm

Optimal energy scheduling is an essential part for microgrid to obtain higher efficiency no matter from technology or economy. However, the flexibility and reconfigurability of the dispatching strategies could not be achieved as the structurally complexity of the microgrid increases. To resolve this issue, a novel hierarchical model of Colored Petri Net (CPN) based dynamic scheduling scheme is first proposed for a class of wind-photovoltaic-storage microgrid, which can be better monitored from the top for the flow of information and thus facilitates energy management. Firstly, the two-layers information flow model of microgrid is established in the platform of CPN Tools, and different layers interact with each other through selected agents. Corresponding parameters of equipment are also derived under the premise of stable operation in the meanwhile. Secondly, the economic objective function is established and solved by Quantum Particle Swarm Optimization (QPSO) algorithm, which fully considers the punishment of government and reward measures for new energy generation and the consumption of electric vehicles (EV) and battery. Finally, the illustrative example on the isolated island mode is implemented by combining the CPN Tools and MATLAB platform. Note that the input data in objective function can be obtained according to the analysis of the state space in CPN tools. The results show that this management method can improve the economical efficiency, which is in line with the enterprise benefits pursued by power companies.

Evaluating the Safety Control Scheme of Railway Centralized Traffic Control (CTC) System with Coloured Petri Nets

The Centralized Traffic Control (CTC) system plays an important role in ensuring safe and efficient rail transportation operations. It is mainly responsible for the implementation and adjustment of the train operation schedule through the automatic control of the station signalling equipment. The major task of the CTC system is to achieve a high rail transportation operation efficiency under the precondition of safety. For this purpose, it is necessary to select appropriate safety control schemes for the CTC system. In this paper, a formal approach is proposed to quantitatively evaluate the operation efficiencies of the CTC system with respect to different safety control schemes. The proposed approach adopts stochastic coloured Petri nets as the means of description for the system model, and evaluates the operation efficiency of the CTC system based on the data collected during the simulation of the system model. To exemplify the proposed approach, the safety control scheme of prohibiting a passenger train from passing a freight train through adjacent rail tracks between two adjacent stations is studied. The results of the case study show the feasibility of the proposed approach.

Modelling and Simulation of Patient Flow in the Emergency Department During the COVID-19 Pandemic Using Hierarchical Coloured Petri Net

The emergency department (ED) faces great challenges during the corona pandemic, which has greatly affected the course of work, as the medical staff works to maintain the quality of service and more guarantee the health of patients and staff. With the rapid spread of the coronavirus, ED has become the focus of attention of many researchers, where most of them focused on reducing waiting time and the duration of the patient's length of stay (LOS) through the restructuring of ED. In this study, the authors propose a simulation model using the hierarchical coloured-petri nets (CP-Nets). Several improvement scenarios have been suggested in order to arrive at the optimal solution. Scenarios were compared and solutions were presented to decision makers. This study was conducted at the Hassani Abdelkader Hospital in Sidi Bel Abbes. The authors obtained a model that could be generalized to other hospitals.

Simulation-based multi-objective optimization for enhanced safety of fire emergency response in metro stations

This study establishes a multi-objective optimization (MOO) model for fire emergency response in the metro station using a simulation-based analysis, in which the emergency response time and the number of firefighters are both minimized. A Hierarchical Timed Color Petri Nets (HTCPN) model is constructed to simulate different scenarios. The Skyline operator is adopted to solve the MOO problem based on the simulated dataset. Eventually, a case study of fire emergency response at the Simenkou metro station in Wuhan is conducted to verify the feasibility of the proposed approach. The case study implies that: (1) The constructed HTCPN model is correct, reasonable, and effective; (2) Compared to the baselines, simulation-based MOO can reduce the number of assigned firefighters and the emergency response time by 38.7% and 31.4%, respectively; (3) After considering the interaction between the firefighting and rescue teams, the average improvement of all scenarios can be further improved. The novelty of this research lies in that: (a) Through Petri nets combined with the emergency response process of metro stations, an HTCPN model is constructed, which appropriately represents the relationship between the relevant parts; (b) The optimal emergency response strategy is given from an MOO perspective based on the simulated dataset, which considers the response time and allocation of firefighters simultaneously.

Security Analysis and Improvement of Vehicle Ethernet SOME/IP Protocol.

The combination of in-vehicle networks and smart car devices has gradually developed into Intelligent Connected Vehicles (ICVs). Through the vehicle security protocol, ICVs can quickly realize communication transmission. However, with the more frequent connections between smart in-vehicle devices and the network, the relationship between intelligent cars and external systems is becoming more and more complicated, and in-vehicle networks are gradually facing many security issues. Strengthening the security of in-vehicle protocols has become particularly important. This paper uses the model building method based on the Colored Petri Net (CPN) theory to model the Scalable service-Oriented MiddlewarE over IP (SOME/IP) protocol of the vehicle Ethernet. The security protocol is formally verified and analyzed by combining it with the Dolev–Yao adversary model detection method. After verification, the protocol is subject to three attack vulnerabilities: replay, tampering, and deception. We introduce timestamps and random numbers to strengthen the protocol security. After the final analysis and verification, the improved scheme in this paper can effectively improve the security performance of the protocol.

An Anonymous Authentication and Key Update Mechanism for IoT Devices Based on EnOcean Protocol.

EnOcean, a commonly used control protocol in smart lighting systems, provides authentication, as well as message integrity verification services, and can resist replay attack and tamper attack. However, since the device identity information transmitted between sensors in smart lighting control systems is easily accessible by malicious attackers, attackers can analyze users’ habits based on the intercepted information. This paper analyzed the security of the EnOcean protocol using a formal analysis method based on the colored Petri net (CPN) theory and the Dolev–Yao attacker model and found that the protocol did not anonymize the device identity information and did not have a communication key update mechanism, so an attacker could easily initiate a key compromise impersonation attack (KCIA) after breaking the pre-shared communication key. To address the above security issues, this paper proposed an EnOcean-A protocol with higher security based on the EnOcean protocol. The EnOcean-A protocol introduced a trusted third-party server to send communication keys to communication devices because devices must obtain different communication keys from the trusted third-party server each time they communicated. Thus, this protocol could resist a KCIA and achieve forward security. Meanwhile, the device identity information was anonymized using a homomorphic hash function in the EnOcean-A protocol, and the dynamic update mechanism of the device identity information was added so that an attacker could not obtain the real identity information of the device. Finally, the formal analysis of the EnOcean-A protocol showed that the new protocol could resist a KCIA and ensure the anonymity and untraceability of the communication device, which had higher security compared with the EnOcean protocol.

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.

An Integrated Method for Solving the Two-Sided Assembly Line Balancing Problems

The problems of parallel two-sided assembly lines balancing (TALB) are nonpolynomial (NP-hard) problems that belong to the field of combinatorial optimization. In most cases, these problems can be resolved with algorithms. To this end, this research adopts colored Petri nets (CPN) and a minimal spanning tree (MST) to address the type I problems for two-sided assembly line balancing problem (TALBP). This research proposes a three-step method. In the first step, a reachability tree chart is built to show potential tasks order assignment. In the second step, the color firing mechanism is employed to determine if the colored conditions are satisfied. The final step uses a MST and a least-time prioritized rule to select the proper tasks for assignment efficiently. These steps will be performed repetitively until all the tasks are properly assigned. Since the whole assignment process is based on graphical and paradigm methods, it can be adopted to lessen the burdens of complex calculations. The end of the research will present the comparison results between the examples from the literature and the method proposed in this research. As indicated by the research findings, employing CPN and an MST for TALBPs (type-I) can obtain even favorable and consistent results over legacy methods, and further optimize workstation design and enhance balance efficiency.

Modelling proof-of-work agreement protocol by coloured Petri nets

Proof-of-work agreement protocol, offered by Keller and Böhme, is analysed by coloured Petri nets and refined. Blockchain technology, based on proof-of-work procedure and Nakomoto consensus negotiations, represents fundamentals of many kinds of cryptocurrency widespread recently. The protocol, called , works in continuous time which is simulated using random exponential distribution function of CPN Tools system, obtained values rounded to map them into discrete time of a coloured Petri net. Hierarchical model consists of an environment subnet and a given number of nodes communicating via an unstructured network represented by a single place; the model of node is further structured based on event handlers of the protocol source specification such as initialisation, activation, message delivering, and termination condition check. Based on the simulation results, modifications of the protocol and its parameters are recommended which improve some imperfections of the protocol.

Data Warehousing Process Modeling from Classical Approaches to New Trends: Main Features and Comparisons

The extract, transform, and load (ETL) process is at the core of data warehousing architectures. As such, the success of data warehouse (DW) projects is essentially based on the proper modeling of the ETL process. As there is no standard model for the representation and design of this process, several researchers have made efforts to propose modeling methods based on different formalisms, such as unified modeling language (UML), ontology, model-driven architecture (MDA), model-driven development (MDD), and graphical flow, which includes business process model notation (BPMN), colored Petri nets (CPN), Yet Another Workflow Language (YAWL), CommonCube, entity modeling diagram (EMD), and so on. With the emergence of Big Data, despite the multitude of relevant approaches proposed for modeling the ETL process in classical environments, part of the community has been motivated to provide new data warehousing methods that support Big Data specifications. In this paper, we present a summary of relevant works related to the modeling of data warehousing approaches, from classical ETL processes to ELT design approaches. A systematic literature review is conducted and a detailed set of comparison criteria are defined in order to allow the reader to better understand the evolution of these processes. Our study paints a complete picture of ETL modeling approaches, from their advent to the era of Big Data, while comparing their main characteristics. This study allows for the identification of the main challenges and issues related to the design of Big Data warehousing systems, mainly involving the lack of a generic design model for data collection, storage, processing, querying, and analysis.

Perimeter Control and Route Guidance of Multi-Region MFD Systems With Boundary Queues Using Colored Petri Nets

Perimeter control based on Macroscopic Fundamental Diagram (MFD) aims to meter the number of transferring vehicles at the periphery of the protected urban region in order to obtain the desired number of vehicles in that region. The advantage of perimeter control is less computational effort, while its drawback is that it may create long queues and delays at the perimeter of the controlled area. For capturing boundary queue dynamics, an enhanced accumulation-based MFD model is proposed using colored Petri Nets by considering transfer flows, boundary queues and travel delays simultaneously. The gated intersections and related road segments on the border of a protected region are modeled as so-called boundary buffers. Based on the enhanced MFD model, anintegrated perimeter control framework is proposed with consideration of travel time and queuing time in buffers. In this framework, the controllers between peripheral and protected region are optimized using model predictive control theory. Then, internal flow controllers are adopted to homogenize traffic density among subregions, and route guidance is also used to balance the number of queuing vehicles among boundary buffers. Simulation results verify the effectiveness of the proposed integrated perimeter control. Furthermore, the impacts of buffer storage capacity on region heterogeneity and trip completion rates are also investigated in this paper. <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">Note to Practitioners</i> —It is challenging to manage traffic congestion in large-scale urban network. Perimeter control provides an accumulation-based methodology with consideration of the existing correlation between traffic density and flow, which is known as MFD. For practical application, the efficiency as well asweakness of potential perimeter control strategies need to be evaluated and improved using customized traffic simulations. Accumulation-based traffic model using Petri Nets is introduced to serve for perimeter control, in which the intersections and road segments on the boundary of each pair of adjacent subregions are modeled as a boundary buffer. Both perimeter control and route guidance are integrated in the proposed control framework considering the queuing vehicles in the boundary buffers. Moreover, the effect of buffer storage capacity on network performances is tested, which is the essential for traffic engineers to design and implement management measures in practice.

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.