Estimating the Probability Distribution of Construction Project Completion Times Based on Drum-Buffer-Rope Theory

Various factors affecting the construction progress are regarded as bottlenecks giving rise to the project duration overrun. The contractor should combine the project schedule with the plan in order to reduce the uncertainty of the project activities. The present research describes the method derived from the theory of constraints (TOC) attempts to enhance the relationship among activities, to revise and further reduce the uncertainty of construction activities to improve the reliability of project progress. The elements of drum, buffer and rope (DBR) in TOC are added to PERT network schedule; through the identification of schedule in the bottleneck process, the implementation plan of the bottleneck is obtained. By measuring buffer time and calculating network schedule buffer time as well as feeding time, the relationship among activities and uncertainty of duration are also improved. To illustrate the impact of DBR applications on improving project schedule reliability, a case of hydropower station as an example is illustrated to show enhanced reliability of scheduling. As compared to program evaluation and review technique network (PERT) simulation, the simulation results showed that the uncertainty of construction progress could be reduced if the DBR are well cooperated mutually.

A Variable-Length Chromosome Genetic Algorithm for Time-Based Sensor Network Schedule Optimization

Scheduling sensor nodes has an important role in real monitoring applications using sensor networks, lowering the power consumption and maximizing the network lifetime, while maintaining the satisfaction to application requirements. Nevertheless, this problem is usually very complex and not easily resolved by analytical methods. In a different manner, genetic algorithms (GAs) are heuristic search strategies that help to find the exact or approximate global optimal solution efficiently with a stochastic approach. Genetic algorithms are advantageous for their robustness to discrete and noisy objective functions, as they are only evaluated at independent points without requirements of continuity or differentiability. However, as explained in this paper, a time-based sensor network schedule cannot be represented by a chromosome with fixed length that is required in traditional genetic algorithms. Therefore, an extended genetic algorithm is introduced with variable-length chromosome (VLC) along with mutation and crossover operations in order to address this problem. Simulation results show that, with help of carefully defined fitness functions, the proposed scheme is able to evolve the individuals in the population effectively and consistently from generation to generation towards optimal ones, and the obtained network schedules are better optimized in comparison with the result of algorithms employing a fixed-length chromosome.

Application of Genetic Algorithm in Time-Based Wireless Sensor Network Schedule Optimization

In recent years, wireless sensor networks (WSN) have been particularly interested, studied and applied very strongly. A sensor network is generally limited in resources and energy, which greatly restrict its applicability. Sensor network optimization in practice is a very diverse with a wide range of applications, whereas sensor network scheduling is important in lowering energy consumption and maximizing network lifetime. However, optimization of sensor network schedule a very complex problem with many constraints that is not trivial to solve by analytical methods. This article discusses a heuristical approach using a genetic algorithm to find an optimal solution for network scheduling. The evaluation of fitness function, as well as selection with crossover and mutation operations help to evolve individuals in the population through generations in an optimal direction.

Creating the agile-model to manage the activities of project-oriented transport companies

This study considers an agile model for the organization of activities of a project-oriented transport company. Building a project-oriented company (project-oriented management) requires an appropriate theoretical base. The agile model of transport company operation has been developed, for which the cycles have been determined, the content of each cycle has been defined, and the flow of information has been simulated. The transformation of information in each cycle of the model has been characterized, taking into consideration the operational specificity of transport companies’ activities. A given model was compared to the main stages of a project’s lifecycle. Two indicators have been proposed such as the degree of project uniqueness and the degree of project complexity that reflect the corresponding project characteristics. The complexity of the project’s operational activities refers to the number of elements and their alternatives. Part of the project is an «operation» that forms a unit of the project’s network schedule. The uniqueness of the project of operational activities means the difference between the current project and other projects, already implemented or is being implemented by the company. The estimation formulae for these indicators have been derived. The proposed indicators for the given example have been calculated; the interpretation of the results has been proposed. The calculation results have demonstrated the adequacy of input-output data and the practical applicability of these indicators. These metrics are not limited to the context of an additional project specification. Their level is proposed to be used in the processes of estimating the time of individual project periods and the agile model’s cycles within the initial stage ‒ creating a product concept model and preparing for implementation. In addition, these indicators could be used effectively for employee remuneration.

Solution of the compromise optimization problem of network graphics on the criteria of uniform personnel loading and distribution of funds

The object of research is a model network schedule for performing a complex of operations. One of the most problematic areas is the lack of a unified procedure that allows finding a solution to the problem of compromise optimization, for which the optimization criteria can have a different nature of the influence of input variables on them. In this study, such criteria are the criteria for the uniformity of the workload of personnel and the distribution of funds. Two alternative cases are considered: with monthly planning and with quarterly planning of allocation of funds and staff load. The methods of mathematical planning of the experiment and the ridge analysis of the response surface are used. The peculiarities of the proposed procedure for solving the problem of compromise optimization are its versatility and the possibility of visualization in one-dimensional form – the dependence of each of the alternative criteria on one parameter describing the constraints. The solution itself is found as the point of intersection of equally labeled ridge lines, which are curves that describe the locally optimal values of the output variables. The proposed procedure, despite the fact that it is performed only on a model network diagram, can be used to solve the trade-off optimization problem on arbitrary network graphs. This is due to the fact that the combination of locally optimal solutions in a parametric form on one graph allows visualizing all solutions to the problem. The results obtained at the same time make it possible to select early dates for the start of operations in such a way that, as much as possible, take into account possible difficulties due to the formation of bottlenecks at certain stages of the project. The latter may be due to the fact that for the timely execution of some operation, it may be necessary to combine two criteria, despite the fact that the possible costs may turn out to be more calculated and estimated as optimal.

Organization of effective interaction between the general contractor and subcontractors using the tools of calendar network planning of construction

This article will discuss the advantages of planning using such elements of organizational and technological documentation as a calendar-network schedule for a more efficient process of managing the production of work during the implementation of an investment and construction project. Also, the main schemes of interaction between the general contractor and the subcontractor will be considered on the basis of key points of their interaction, such as the construction contract and especially the schedule for the construction and installation work. The article will outline the established and most common way of interaction in the Russian Federation, show its advantages and disadvantages, as well as a more progressive approach aimed at improving the relationship between commercial entities, construction organizations and customers.

MANAGEMENT OF PROJECT IMPLEMENTATION DURATION AT AN INDUSTRIAL ENTERPRISE

Implementation of investment projects contributes to the development of each metallurgical enterprise. An important project management process is project time management, which includes forecasting and monitoring compliance with deadlines, monitoring the content and relationships between works, as well as assessing the resources required for each work. When planning a project, it is often not possible to accurately determine the duration of a network schedule. Uncertainty of work time is associated with a certain degree of uniqueness of each work and external factors influencing this work. The method of network planning is recognized as one of the most effective methods used in the theory of project time management. Thanks to network models, it is possible to determine one of the key characteristics of the project, namely its duration. Due to the fact that it is not possible to accurately determine the duration of a project, so it is obvious the relevance of the use of network models that allow you to take into account the uncertainty in the time of work. The purpose of this work is to develop a probabilistic simulation model for calculating the duration of the project to create a combined gas turbine power plant at a metallurgical enterprise. It is proposed to take into account the uncertainty in the duration of the project in the traditional way, it is assumed that the duration of the project has a beta distribution. The work uses a network schedule for the creation of a combined gas turbine power plant. And all the works of the project were divided into appropriate stages. With the help of experts who provided a pessimistic, optimistic and most likely estimate of the duration of the work, the parameters of the beta distribution were determined. As part of the algorithm for calculating the simulation model of the project, 200 implementations of a random variable - the duration of work were generated and, accordingly, 200 implementations of the critical path of the project were obtained. the main characteristics of the specified set of random numbers are determined. Then we found a value for the duration of the critical path, which with a probability of 95% will not exceed 21 months.

Managing Graphics Training in Digitalized Environment

The article is devoted to the management of subject learning based on the principle of individualization in the context of the digital transformation of the educational process. Individualized learning technologies help increase student interest in achieving better results. The expediency of using such learning technologies that are focused on individualization has been proven, since individually oriented learning helps to stimulate students to achieve better results. Basic graphic preparation of students is used as an example of subject preparation. There is an example of a prepared educational resource-an electronic workshop, which presents a database of geometric problems with creative content. The necessity of using a practice- oriented project task for the purpose of introducing to professional creativity and mastering methodology of independent work with maximum disclosure of their individual potential is shown. The scheme of working at a project in a digital environment is considered. The target settings of subject-based learning are highlighted. The network schedule of planning individual work of students taking into account different levels of immersion in project activities is discussed. The authors demonstrate a set of tasks for the design of 3d models of objects of varying complexity, contributing to the formation of competencies in the practical implementation of algorithms for geometric constructions. It is concluded that the use of electronic educational resources in the process of basic geometric and graphic training makes it possible to bring the training support closer to the real professional design environment as well as introduces students to the latest innovative technologies.

USING THE PERT METHOD IN CALCULATING LABOR COSTS AND RATIONING THE WORKING TIME OF CONTRACT SERVICE EMPLOYEES IN PROCUREMENT ACTIVITIES

Today, close attention is mainly paid to the aspects of placing an order, and the calculation of the effectiveness of procurement activities is based on a reduction in the contract price. At the same time, the optimization of the working time of contract service employees and the rationing of their labor are important areas of organizing an effective procurement system. The article presents the results of the calculation of labor costs for the organization of procurement activities and the implementation of accounting policies, based on the generalization of data from expert reports. Representatives of contract services, economists, lawyers, accountants, engineers, business managers, procurement specialists, contract managers were involved as experts. The obtained materials were used to build a network schedule for the process of work execution and delivery of goods using the PERT method. It is revealed that the main task of conducting effective procurement activities is to ensure uninterrupted and high-quality work of all employees of the organization. It is proved that the development of the customer's professionalism in the field of procurement is a key direction for improving the contract system. The conducted research will allow the managers of customers to balance their labor resources, improve procurement activities, avoid inappropriate spending of budget funds, and increase the efficiency of procurement.