# Project Robust Scheduling Based on the Scattered Buffer Technology
## 6 Conclusions  
Based on the principle of scattered buffer, this paper develops the unit activity slack scattered buffer heuristic algorithm, which is different from the original simulation algorithm proposed in the literature based on prior knowledge. This algorithm does not depend on the probability distribution that is given in advance of the project activity duration, but analyzes key factors that influence the stability of the schedule to establish the measure index of the robustness to directly calculate and determine the location and the size of the buffer insertion. Because of the complexity of disruptions and the lack of realized sample data, in most cases, the probability distribution of the activity duration is difficult to obtain. Therefore, the application of simulation algorithm has certain limitations. On the contrary, this algorithm can be applied to any generation of the robust schedules that distribute randomly. The experiment also proves that this algorithm possesses stronger applicability and practicability.  
In the algorithm in this paper, because the iterative process is used to set buffer time for the solution activity step by step, namely there is only one unit of time buffer set for the solution activity in each iteration, when the scale of project is much larger, and the number of constraints among activities is further increasing after the resource flow network is introduced at the same time, the number of predecessors of the solution activity becomes very large. In other words, to calculate the value of \(USA\) in all solution activities is very time-consuming, which is also the limitation of this algorithm. However, the improvement of the iterative algorithm can shorten the iteration time.  
In practical application, according to the actual situation of uncertain project duration, the project manager can consider different probability distribution for each activity's duration variables to set different buffer time target-oriented for activities in project and to work out a project scheduling with strong robustness. The implementation of a robust scheduling with scattered buffers can effectively reduce the impact of environmental interference on the schedule, reduce the rescheduling and tardiness of the project schedule, reduce the construction costs, and facilitate the schedule management for the project manager.  
The robust scheduling problem under uncertain project environment is a very complex subject, involving many factors, such as the complexity of network structure and the inherent uncertainty of the project. This paper only considers the zero-lag precedence relations among activities and uncertain activity duration and some other general situations, but it does not discuss the generalized precedence relations and other uncertain complicated factors, such as the demand for resources or the uncertain work content. Only considering these complex factors comprehensively can we find effective solutions for the project robust scheduling problem, which has more research value. This is also an interesting topic worthy of further research.  
The work presented here was carried out in collaboration between all authors. [PERSON] and [PERSON] defined the research theme. [PERSON] and [PERSON] designed methods and simulation experiments, carried out the simulation experiments, analyzed the data, interpreted the results and wrote the paper. [PERSON] co-designed experiments, discussed analyses, interpretation, and checked the paper. All authors have contributed to, seen and approved the manuscript.  
The authors declare no conflict of interest.