Network-based Modeling Of Large-scale Engineering Project And Analysis Methods Of Critical Nodes

The large-scale engineering project is the typical complex system, whichcomposed of thousands of interdependent tasks and participates. The increasing of sizeand complex relationship among tasks and organization are bringing about the increasedproject uncertainties, management difficulties and low efficiency. How to describe theinteraction relationship between tasks and organizations, how to model the large-scaleengineering project, how to identify and practice key-point management on the criticalelements to optimize project resource, improve the management efficiency and decisionmaking, come into being the urgent problems of large scale project management.Using the system analysis methodology and guiding by the integrationmethodologies of qualitative and quantitative, this paper aims to establish the networkanalysis model of large-scale engineering project. Based on the integrated model, usingfor reference from networks modeling theory and methodology to identify and analysisthe critical organization and tasks nodes that having the important influence on theproject scheduling. In view of various risk factors during project implementationprocess and considering the conditions of the uncertain project completion time, thispaper uses the network topology structure and system interdependent relationship toprovide decision aiding for managers to practice key-point management on the criticalelements. Introducing the networks model and analysis methodology into large scaleproject management, not only expand the traditional project management theory, butalso provide the technical method and support in seizing the focus of the task planningand organization management, improving the macro overall planning capability ofmanagers.The main results and contribution of this dissertation are as follows:1. The organization-task interdependent network model is proposed. Toovercome the shortage of treating the organizations and tasks separately in the researchof project management, the organization-task interdependent network model isestablished. Based on the new model, the importance of project tasks and organizationscan be evaluated using the network index of social network theory, which makes up thelack of traditional theories, such as critical path method and program evaluation reviewtechnique in project tasks analysis; What’s more important is that the new modelintegrates the project participant organizations, making it possible to analyze andevaluate the importance of project tasks in a systematical way.2. The virtual nodes algorithm based on the decomposition of weighted edgesis proposed to solve the calculation complexity of betweenness centrality. At first,the practical meaning of network index in large scale project is defined and analyzed, and the calculation method is provided. Then, in order to solve the calculationcomplexity of betweenness centrality, the virtual nodes algorithm based on thedecomposition of weighted edges is proposed, which improve and optimize thecalculation method of betweenness centrality. The relationship between network meandegree, average edge weight and time complexity based on the virtual nodes algorithmis analyzed and deduced. By numerical simulation, the calculation efficiency ofbetweenness centrality with Brandes’ algorithm with either the traditional Dijkstra’salgorithm or the virtual node algorithm is compared, and the time efficiency of newalgorithm is validated. The new algorithm lay a foundation for subsequent analysis ofnetwork index.3. Analysis method of Critical task nodes based on Flow degree is proposed. Anew network measurement for analyzing the correlation between project networktopology and critical paths is proposed.1600different project networks are generatedby RanGen2and the correlation between nodes’ betweenness centrality, indegree,outdegree, and flow degree are analyzed. Simulation results reveal that when the taskduration is unknown, the match ratio could achieve as high40%-80%for critical pathestimation based on indegree, outdegree and flow degree. Flow degree shows thehighest correlation with critical paths, and it has the most important effect on the projectcompletion time for nodes on the non-critical paths as well.4. The concept of orgazniational malfunction is proposed, a new method toanalyze orgazniational malfunction and indentify critical orgnaization nodes isestablished. By modeling the interacting dependencies between project participantorganizations and project tasks in large-scale engineering project system, wetheoretically analyze the effect of organizational structures, e.g., random structures,centralized structures and hierarchical structures, on project completion time areanalyzed. Results show that the project completion time is much higher when certainproportion of organizations is under priori failure than random failure. What’s more, thewhole network will collapse down with relatively small proportion of nodes under priorifailure. The assumptions and methods used in the cascading failure modeling enable usto provide means for evaluating the criticality of organizational nodes in large-scaleengineering systems.