Investigation of Critical Activities in a Network with Point-to-point Relations

Bokor, Orsolya; Hajdu, Miklós

doi:10.1016/j.proeng.2015.10.078

Cited by 11 publications

(6 citation statements)

References 3 publications

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“…This is also true for piecewise linearly segmented activities as shown in Figure 2g, which generate similar constellations, because their segments are bounded by slope changes. These findings do not contradict the conjecture, which had allowed "inner" points , i.e., mid-point relations, in referring to a previously published generalization (Bokor and Hajdu 2015;Hajdu 2015c). Third, a generalization of influence lines toward influence surfaces presents a detailed visualization of how three activities can dynamically interact.…”

Section: Contributions and Recommendationssupporting

confidence: 71%

Precedence permutation patterns creating criticality constellations: Exploring a conjecture on nonlinear activities with continuous links

Lucko

2018

Organization, Technology and Management in Construction: An International Journal

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Abstract:The inaugural challenge of the 2016 Creative Construction Conference has posed two related questions on how many possible criticality constellations with different behaviors for delays and acceleration exist and how said constellations can occur for nonlinearly and monotonously progressing activities that have continuous relations. This paper systematically solves these questions by performing a thorough literature review, assembling theoretical foundations for link constellations, performing a computer simulation of all possible permutations, and providing a mathematical proof by contradiction. It is found that (for the initially assumed self-contained activities in a network schedule that exhibit only a linearly growing production), three newly hypothesized criticality constellations cannot exist. Nonlinear activity constellations with diverging or converging relative productivities are examined next. Lags in networks become buffers in linear schedules. It is found that a nonlinear curvature of the progress may induce middle-to-middle relations besides those between start and finish. If multiple curvatures are allowed, then partial segments can form relations, which increase the number of criticality constellations. This paper is extended from the 2017 Procedia Engineering conference version.

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Section: Contributions and Recommendationssupporting

confidence: 71%

Precedence permutation patterns creating criticality constellations: Exploring a conjecture on nonlinear activities with continuous links

Lucko

2018

Organization, Technology and Management in Construction: An International Journal

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“…Researchers [29] pointed out that the Critical Path Method (CPM) is the most frequently used method to plan and control the construction execution process. The CPM method facilitates the analysis of delays in (1) supporting the computation of project duration, shortest path, and critical path [30] and (2) analyzing the delayed activities' impact on the duration [31]. However, the CPM also has shortcomings.…”

Section: Delay Analysis Of Construction Managementmentioning

confidence: 99%

IFC-Based 4D Construction Management Information Model of Prefabricated Buildings and Its Application in Graph Database

et al. 2021

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Effective data interoperability and schedule analysis play a significant role in improving the management of prefabricated buildings. However, there is a lack of efficient strategies and comprehensive approaches for data interoperability and data-based automated schedule analysis. This paper intends to promote prefabricated buildings’ management by solving these two problems via developing an IFC-based framework consisting of three parts. Firstly, this framework proposed a mechanism to establish an IFC-based 4D construction management information model of prefabricated buildings. Furthermore, a non-relational database—graph database—is introduced to twin this model into a task-centered network to realize the interoperation of construction information among different participants. Finally, graph database-based strategies to update data, automatically analyze construction schedules and visualize the 4D construction management information model are described. The proposed framework is validated in a prefabricated engineering case. In this case, an IFC-based and graph database-based 4D construction management information model is established through IFC standard’s extension. The graph database-based analysis of the model automatically recognizes the engineering case’s critical path information, delay analysis information, and schedule network analysis information. It is illustrated that this framework can successfully establish a unified IFC-based information model of prefabricated buildings’ construction management to prompt effective data interoperability. In addition, the application of this IFC-based information model in graph database can automatically analyze the construction schedules to prevent possible delays in advance. In short, the significance of this paper is to innovatively propose an IFC-based and graph data-based information model to solve the difficulties of ineffective data interoperation and unautomated schedule analysis in prefabricated buildings’ construction management. This study can be the digital foundation of further IFC-based digital twin.

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“…The results showed that the operating capabilities of city pairs between different airlines are spatially related, which were conducive to the reasonable development strategies for emerging low-cost airlines. Bokor et al [22] applied the city-to-city network to engineering practice projects, and the changes of specified projects have an impact on the whole. Never et al [23] found the potential driving factors and obstacles related to airline network connectivity, guided by innovation diffusion theory, and analyzed qualitative and quantitative data using the method of triangulation to provide references for airlines to make plans.…”

Section: Literature Reviewmentioning

confidence: 99%

Environmental Impact and External Costs Associated with Hub-and-Spoke Network in Air Transport

et al. 2021

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Under the background of economic globalization, the air transport industry developed rapidly. It turns out that the city-to-city network has not been able to adapt well to the development of the society, and the hub-and-spoke network came into being. The hub-and-spoke network demonstrates the advantages of reducing the operating costs of airlines to keep a competitive advantage, and by maintaining the interests of airlines in the rapidly developing context. However, during the operation of aircrafts, they consume fuel and spew a great deal of harmful pollutants into the air, which has an adverse impact on the living environment. This paper explores the impact and external costs associated with hub-and-spoke network in air transport from an environmental perspective. With some mathematical models, we construct a hub-and-spoke network and take a quantitative study on the environmental impact of air transport. For calculating pollutant emissions, meteorological conditions were considered to revise the pollutant emission factors of the Engine Emissions Data Base (EEDB) published by International Civil Aviation Organization (ICAO). The environmental external costs measurement model is employed to calculate the externality of toxic gas and greenhouse gas (GHG). In order to make the study more convincing, two alternative networks are computed: hub-and-spoke network and city-to-city network. It is found that the hub-and-spoke network is associated with poorer environmental impact and environmental external costs because of the different network characteristics and the scale of the fleets. Therefore, under the general trend of green aviation, the environmental impact and environmental external costs associated with hub-and-spoke network in air transport provides a certain reference for airlines’ strategic decision-making.

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Investigation of Critical Activities in a Network with Point-to-point Relations

Cited by 11 publications

References 3 publications

Precedence permutation patterns creating criticality constellations: Exploring a conjecture on nonlinear activities with continuous links

Precedence permutation patterns creating criticality constellations: Exploring a conjecture on nonlinear activities with continuous links

IFC-Based 4D Construction Management Information Model of Prefabricated Buildings and Its Application in Graph Database

Environmental Impact and External Costs Associated with Hub-and-Spoke Network in Air Transport

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