Graphical Modeling Tool Research Articles

Modeling and Simulation of Projects with Petri Nets

Traditional project management tools and other revised tools are limited in representation of the problem and in dealing situation dynamically. This paper details the use of Petri nets as a graphical and mathematical modeling and simulation tool in project management. In this context, the benefits of Petri nets are indicated. A Petri net aided software, a PETRI-PM is developed to model, simulate and analyze the project. Extensions to make Petri nets suitable for project management applications are proposed. The use of a PPC-matrix for token movements is proposed. The paper also discusses the implications of the model and the analysis it supports. The usefulness of the software is exemplified with a case study.

An ontology-based support for product conceptual design

The research presented in this paper is a follow-up of our prior work involving the development of a graphical modeling tool to support designers at the conceptual design stage. To close the loop for supporting designers in generating design concepts flexibly, fast, and easily, an ontology-based approach for knowledge management that works along with the graphical modeling tool is discussed. Ontology and databases for the tool are developed to promote the systematic capture of design knowledge and efficient reuse of the design knowledge selection. In order to locate the proper information and query the data from the databases, the relationship between the ontology and databases, the data analysis process, ontology enrichment, and the ontology-based query engine are built to offer users multiple design results according to users’ requirements. A tire design example is presented to demonstrate the proposed approach. The ontology-based method described in this paper can help retrieve and save the complex relations, support the reasoning, integrate heterogeneous data resources and offer users more accurate, proper and comprehensive data.

Bio-jETI: a service integration, design, and provisioning platform for orchestrated bioinformatics processes

BackgroundWith Bio-jETI, we introduce a service platform for interdisciplinary work on biological application domains and illustrate its use in a concrete application concerning statistical data processing in R and xcms for an LC/MS analysis of FAAH gene knockout.MethodsBio-jETI uses the jABC environment for service-oriented modeling and design as a graphical process modeling tool and the jETI service integration technology for remote tool execution.ConclusionsAs a service definition and provisioning platform, Bio-jETI has the potential to become a core technology in interdisciplinary service orchestration and technology transfer. Domain experts, like biologists not trained in computer science, directly define complex service orchestrations as process models and use efficient and complex bioinformatics tools in a simple and intuitive way.

Energetic Macroscopic Representation and Inversion-based Control: Application to an Electric Vehicle with an Electrical Differential

Energetic Macroscopic Representation (EMR) is an energy-based graphical modelling tool to describe complex electromechanical systems. It is based on the action-reaction principle to organize the interconnection of sub-systems according to the physical causality (i.e. integral causality). Moreover, an inversion-based control can be systematically deduced from EMR using specific inversion rules. The aim of this paper is to introduce the basics of EMR approach and its inversion-based control. An Electric Vehicle with an electrical differential is studied as a simple example.

Modeling, Control, and Validation of an Electro-Hydraulic Steer-by-Wire System for Articulated Vehicle Applications

X-by-wire control systems in automotive applications refer to systems where the input device used by the operator is connected to the actuation power subsystem by electrical wires, as opposed to being connected by mechanical or hydraulic means. The "X" in the X-by-wire is replaced by "steer", "throttle", and "brake" to represent the steer-by-wire, throttle-by-wire, and brake-by-wire systems. Common to all of these subsystems is that the operator control input device (i.e., steering column, acceleration pedal, and brake pedal) is not connected to the actuation devices mechanically. Rather, it is connected to an embedded computer which, in turn, sends the control signals to the actuation devices. Current state of art steering systems used in articulated vehicles are hydro-mechanical type systems, i.e., the steering column motion is transmitted and amplified by the main hydraulic circuit by hydro-mechanical means. This paper presents a new steer-by-wire (SBW) system which we designed, modeled, analyzed, and tested on wheel type loader construction equipment. The simulation results and tests conducted on a prototype development vehicle (a medium size wheel type loader) show very good agreement. The control algorithm is modeled using graphical modeling tools similar to Simulink and StateFlow. A real-time control algorithm is implemented on a Motorola 68332 microprocessor-based embedded controller. The operational performance of the steer-by-wire system has been convincingly demonstrated.

Optical Network Design with Optical Constraints in IP/WDM Networks

In this paper we consider algorithms for the logical topology design and traffic grooming problem in WDM networks with router interface constraints as well as optical constraints. The optical constraints include restricted transmission range due to optical impairments as well as limits on the number of available wavelengths. We formulate this problem as an integer linear program which is NP-complete. We then introduce heuristic algorithms which use a graphical modeling tool called the Virtual Neighbor Graph and add lightpaths sequentially. The best performing heuristic uses a so-called Resource Efficiency Factor to determine the order in which paths are provisioned for the traffic demands. By giving priority to demands that can be routed over paths that make efficient use of network resources, it is able to achieve good performance both in terms of weighted hop count and network throughput. For finding optimal multi-hop paths sequentially, we introduce interface constraint shortest path problem and solve it using minimum weight perfect matching.

Modelling and analysis of a system based on symbolic representation of logic

ABSTRACTPetri nets are powerful graphical and mathematical modelling tool for describing and studying various types of system. Petri nets can be used not only to express the static behaviours of logic operation such as logical relations between system components, but also to study the dynamic behaviours such as operating sequence, workflow, maintenance process, failure occurrence and concurrent activities of the system Petri net model has been developed for LHD motor-overheating problem. The study utilises the Petri net approach in the above problem to demonstrate failure analysis. Petri nets have been used to identify minimum cut sets finding, marking transfer, firing sequence, reachability tree and dynamic behaviour of machine failure. Fault propagates from basic place to top place. It is almost a rule that no equipment can breakdown without showing prior signal of malfunctioning. A model is formulated for fault detection and isolation.

Fault detection and isolation of smart actuators using bond graphs and external models

This paper deals with fault detection and isolation (FDI) of smart actuators combining the benefits of bond graph modelling with external models. An external model is a generic method which can be used to specify and verify the functional specifications of smart equipment. It uses the concept of services provided to the user and the organization of operating modes as a state graph with the logical conditions (depending on available services) required to move from one operating mode to another. One drawback of the external model is that it describes the system in terms of functions without taking into account the dynamics of the equipment. In addition, the availability of the services is not determined by FDI procedures. The integration of the bond graph methodology as a graphical and multi-disciplinary modelling tool quantifies the services by associating one or more bond graph elements to each service. Furthermore, the causal and structural properties of the bond graph methodology can be used to design FDI algorithms (i.e. the generation of fault indicators) to determine the availability of the services. This information is used to determine the transition conditions in the state graph. This technique has been applied to monitor a complex pneumatic servo-positioner.

Optimal Legal Firing Sequence of Petri Nets Using Linear Programming

Petri nets (PNs) are a reliable graphical and mathematical modeling tool for the formal modeling and validation of systems (W. Reisig, A Primer in Petri Net Design, Springer-Verlag: Berlin, Heidelberg, 1992). Applications of PNs include discrete event dynamic systems (DEDS) that are recognized as being concurrent, asynchronous, distributed, parallel, and/or nondeterministic. It is also a powerful formal method for the analysis of concurrent, embedded, and distributed finite state systems (K. Varpaaniemi, Series A: Research Reports, No. 26, Helsinki University of Technology, Digital Systems Laboratory, Oct. 1993). The reachability analysis of PNs is strategically significant as it captures the dynamic behavior of the system as well as providing efficient verification of the correctness of the model. Few linear programming (LP)-based methods can be found that address the reachability problem, and some of these are suitable for optimal control problems. However, due to an inherent state explosion they are difficult to implement; other methods run easily into deadlock as they lack appropriate mechanisms to avoid the firing of critical transitions (T. Matsumoto and A. Tarek, in Proceedings of the 35th IEEE Conference on Decision and Control, Kobe, Japan, 1996-12, pp. 4459–4468). In this paper an improved and easy to implement method is proposed that combines the Optimality Principle and Linear Programming (OP + LP) techniques to find an Optimal Legal Firing Sequence (OLFS) in PNs. This method can be applied to ordinary PNs with self-loops, avoids deadlocks, and can also be used for general PNs having cycles.

Developing complex signaling models using GENESIS/Kinetikit.

The development of biologically realistic models of signaling pathways is a demanding process, involving computational challenges as well as those arising from the complexity of detailed pathway models. We have developed the General Neural Simulation System (GENESIS) and Kinetikit (GENESIS/Kinetikit), a graphical simulation environment for modeling biochemical signaling pathways using deterministic and stochastic methods. A library of models of several common signaling pathways complements the software. This combination of numerical computation engines, graphical modeling tools, and library of models is designed to build on the cumulative development of models and techniques from many sources. The complete simulation environment and demonstration models are available from (http://stke.sciencemag.org/cgi/content/full/sigtrans;2004/219/pl4/DC1; also at http://www.ncbs.res.in/~bhalla/kkit/download.html). The associated library of signaling pathways is based on published experimental and simulation studies and is curated to ensure that the simulation outcomes match published results. Models in the library are maintained in a database (http://doqcs.ncbs.res.in). Individual pathway models can be combined to build complex signaling network simulations. The overall goal of this process is to attain sufficient biological realism in models to directly compare their outcomes with experiments and to improve our understanding of complex signaling.

Petri net-based scheduling of construction projects

Scheduling of construction projects is an important planning function that provides a clear picture of the construction activities, construction sequence, and construction resources to the agencies involved in construction. In this paper a Petri Net-based scheduling method that is geared towards resource-based scheduling of construction projects is described. Petri Nets are graphical and mathematical modeling tools that can be used to perform static and dynamic analysis of systems. Under the proposed technique Generalized Stochastic Petri Net (GSPN) modeling elements are used to develop a construction schedule. Resources required to accomplish construction work tasks are explicitly identified and allocated to the corresponding work tasks. In addition the technique provides hierarchical features that allow top–down breakdown of a construction project and modular features to schedule repetitive units. The paper summarizes the steps required to perform scheduling of construction projects using the proposed technique and highlights its advantages. The scheduling of a sample bridge project also highlights the significant benefits of the method.

Modeling uncertainty reasoning with possibilistic petri nets

Manipulation of perceptions is a remarkable human capability in a wide variety of physical and mental tasks under fuzzy or uncertain surroundings. Possibilistic reasoning can be treated as a mechanism that mimics human inference mechanisms with uncertain information. Petri nets are a graphical and mathematical modeling tool with powerful modeling and analytical ability. The focus of this paper is on the integration of Petri nets with possibilistic reasoning to reap the benefits of both formalisms. This integration leads to a possibilistic Petri nets model (PPN) with the following features. A possibilistic token carries information to describe an object and its corresponding possibility and necessity measures. Possibilistic transitions are classified into four types: inference transitions, duplication transitions, aggregation transitions, and aggregation-duplication transitions. A reasoning algorithm, based on possibilistic Petri nets, is also presented to improve the efficiency of possibilistic reasoning and an example related to diagnosis of cracks in reinforced concrete structures is used to illustrate the proposed approach.

Aplicación de redes de petri a la evaluación de desempeño de sistemas de comunicaciones

Performance evaluation of communications systems is usually done by analytical techniques or simulation. The analytical approach is normally based on a probabilistic description of the system operations in terms of Markovian processes or queuing systems, but only is directly applicable for simple systems, or simplistic models of complex systems. Simulation is a powerful tool but requires enormous computations to yield accurate performance estimators. In this paper we present an alternative technique: Petri Nets, a graphical and mathematical modeling tool applicable to many systems. We used Stochastic Petri Nets to model and evaluate queuing systems and some protocols. Simple and accurate models were developed. The main definitions relating Petri nets in general, and to the particular classes of Petri nets are summarized in Section 1. The following sections contains queuing models (Section2 ), Stop and Wait and Aloha protocols (Section 3), DSP protocol (Section 4). Section 5 concludes the paper.

HIERARCHICAL AND MODULAR MODELING OF STRUCTURAL STEEL ERECTION PROCESS USING PETRI NETS

The construction industry is growing at a fast pace-newer project delivery methodo logies are being adopted; design of facilities is continuously improving, newer means, methods, and materials of construction are being used. All these market forces have re sulted in an increase in complexity of on-site construction processes. The construction industry needs advanced tools and techniques to plan and manage these complex con struction processes. This paper describes and utilizes a Petri Net based hierarchical and modular modeling and analysis technique for the planning of complex construction pro cesses. Petri Nets are graphical modeling tools that have been utilized in the modeling and analysis of processes in the fields of software engineering, telecommunications, manufac turing, and construction. This paper highlights advanced features of Petri Nets and their utilization in the modeling and analysis of structural steel erection processes. Through the use of hierarchy, modularity, and resource modeling Petri Nets provide clear advan tages in the modeling of complex construction processes.

Towards a communicating petri net tool for modeling production processes

This paper presents an analysis of the process concept based on the ⪡Events, Activities and Process⪢ oriented approach. The analysis has been conducted by constructing a comparison table between the several elements of a process. Several tools exist in the literature for the production processes modeling (IDEF0/IDEF3, DFD, Flowcharts, Petri Nets). We are particularly interested in modeling with the Stochastic Petri nets tool. This graphical tool is presented and analyzed for process modeling. The need for defining a communication policy between the activities of a production process when dealing with graphical modeling tools is explained. In this context, the requirement specifications to establish the mentioned communication policy are defined. These specifications tend to determine the links and the types of relations between the activities.

Computer simulation of hypothermia during "damage control" laparotomy.

"Damage control" is a surgical strategy for the staged repair of severe trauma that aims to avoid an irreversible physiologic insult marked by a self-propagating combination of hypothermia, coagulopathy, and acidosis. The point beyond which the physiologic insult becomes irreversible, however, remains ill-defined. The aim of this study was to address this problem by means of a dynamic computer model of heat loss during laparotomy for exsanguinating hemorrhage. A single compartment model was developed using a graphic modeling tool and was implemented to calculate the time interval from the beginning of laparotomy to a core temperature of 32 degrees C, which is a marker of irreversible physiologic derangement in injured patients. A series of simulation runs showed that the exposed peritoneum is the dominant factor contributing to heat loss; the bleeding rate has a less marked effect. Elevation of the ambient temperature and rapid abdominal closure are effective interventions available to the surgeon to modify the heat loss curve. This study shows that during a "damage control" laparotomy for exanguinating hemorrhage the window of opportunity for salvage before the onset of an irreversible physiologic insult is no longer than 60 to 90 minutes.

Modeling and Analysis of Concrete Production Plant Using Petri Nets

Computer modeling and analysis of construction processes have gained importance in recent years because of an increase in the complexity of construction processes. Petri nets provide a modeling and analysis approach that can be used to effectively study, understand, analyze, and improve construction processes. This paper highlights the advanced features of petri nets and describes their utilization as a process modeling and analysis tool for the study of a ready-mix concrete plant. Usually process modeling and analysis are performed by initially developing a graphical portrayal of the process and then dynamically studying the response of the process to external and internal factors. A petri net is a formal graphical modeling tool that can be efficiently utilized as a process modeling and analysis tool because it can graphically portray and dynamically analyze a process in an integrated manner. The paper contributes significantly in the area of computer-based decision making and provides value to practicing schedulers, estimators, and project managers who deal with complex construction processes.

Modeling and analysis of a mail processing plant using Petri nets

This article outlines the utilization of Petri nets as a computerized process modeling and analysis tool for the study of the Edmonton Mail Processing Plant (MPP). Development of new systems or designing improvement in existing system—such as the MPP—are some of the challenges faced by decision makers and managers on a regular basis in the industry. In order to make prudent decisions, modeling and analysis of the underlying processes that constitute new or existing systems has become essential. Usually process modeling and analysis is performed by initially developing a graphical portrayal of the process and then by dynamically studying the response of the process to external and internal factors. In this article an overview of Petri net based process modeling and analysis is provided. Petri net is a formal graphical modeling tool that can be efficiently utilized as a process modeling and analysis tool because it can graphically portray and dynamically simulate a process in an integrated manner. The objective of this article is to highlight the symbolic graphic format and dynamic simulation capabilities of Petri nets. The article contributes significantly in the area of computer based decision making and provides value to practicing engineers and project managers who manage complex tasks.

A graphic modeling and analysis tool for human fault diagnosis tasks

This study presents a graphic modeling and analysis tool for use in constructing an operator's mental model in fault diagnosis tasks. In most automatic and complicated process control systems, human fault diagnosis tasks have become increasingly complex and specialized. The system designer should consider the cognitive process of human operator to avert failure of implement action owing to a lack of compatibility between humans and aiding system interface. Here, an experiment is performed to investigate the nature of human fault diagnosis. A graphic modeling and analysis tool is then proposed to model the continuous process of human fault diagnosis. The approach proposed herein exploits both the line-chart and Petri nets to demonstrate the operator's thoughts and actions. Moreover, results in this study are integrated into an adaptive standard diagnosis model that can assess the operators' mental workload and accurately depict the interactions between human operator and aiding system. Relevance to industry Automatic intelligent diagnosis systems can not provide satisfactory operating performance. Human diagnosticians are more effective than computer ones. Results in this study offer further insight into an operator behavior in graphic form and also how to design a better aiding system.

An object-oriented modelling framework for automated manufacturing system

Proposed in the paper is an object-oriented modelling OOM framework, called a JR-net modelling framework, for automated manufacturing system AMS design. The proposed modelling framework, which consists of a graphical modelling tool called JR-net job resource relation-net and a modelling building procedure, is the same as the current practice of AMS design and is based on the OOM paradigm. In other words, a virtual prototype of AMS is constructed step-by-step based on a three-phase modelling approach: Static layout modelling object model ; job flow modelling functional JR-net model ; supervisory control modelling dynamic model . A functional JR-net model is a directed graph in which the standard resources of an AMS become nodes and job transfers among the resources become the arcs of the graph. A complete dynamic JR-net model is obtained by specifying supervisory control requirements using tokens in the functional JR-net model. The usefulness of the proposed OOM framework is demonstrated by applying it to the modelling of an AS RS. Also addressed are implementation issues of JR-net models.