Program Evaluation And Review Technique Network Research Articles

Program Evaluation and Review Technique (PERT) Analysis to Predict Completion Time and Project Risk Using Discrete Event System Simulation Method

The prediction of project completion time, which is important in project management, is only based on an estimate of three numbers, namely the fastest, slowest, and presumably time. The common practice of applying normal distribution through Monte Carlo simulation in Program Evaluation and Review Technique (PERT) research often fails to accurately represent project activity durations, leading to potentially biased project completion prediction. Based on these problems, a different method is proposed, namely, Discrete Event Simulation (DES). The research aims to evaluate the effectiveness of the simmer package in R in conducting PERT analysis. Specifically, there are three objectives in the research: 1) develop a simulation model to predict how long a project will take and find the critical path, 2) create an R script to simulate discrete events on a PERT network, and 3) explore the simulation output using the simmer package in the form of summary statistics and estimation of project risk. Then, a library research with a descriptive and exploratory method is used for data collection. The hypothetical network is used to obtain the numerical results, which provide the predicted value of the project completion, the critical path, and the risk level. Simulation, including 100 replications, results in a predicted project completion time and a standard deviation of 20.7 and 2.2 weeks, respectively. The DES method has been proven highly effective in predicting the completion time of a project described by the PERT network. In addition, it offers increased flexibility.

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.

An approach to reengineering applied to control of container logistics cost using the PERT network

With the development of society and the advancement of science and technology, Chinese automobile manufacturers are struggling with increasingly intense competition in the market. To earn a place in the industry and improve brand competitiveness, many companies are beginning to focus on the logistics of cost control, such that the whole supply chain cost is at its lowest when the value is at its highest, as this is the key to the future survival and development of China's automobile industry. As an example, this paper uses the container transport of Changan Ford auto parts logistics, and based on the cost analysis derived from the program evaluation and review technique (PERT), the existing transport process is reengineered. Through the comparison of the costs before and after the transformation and the sensitivity analysis based on the reengineered process, it is determined that the reengineered process is superior to the initial process and exhibits strong practical guiding significance for logistics cost control and the development of China's automobile companies.

An approach to reengineering applied to control of container logistics cost using the PERT network

With the development of society and the advancement of science and technology, Chinese automobile manufacturers are struggling with increasingly intense competition in the market. To earn a place in the industry and improve brand competitiveness, many companies are beginning to focus on the logistics of cost control, such that the whole supply chain cost is at its lowest when the value is at its highest, as this is the key to the future survival and development of China's automobile industry. As an example, this paper uses the container transport of Changan Ford auto parts logistics, and based on the cost analysis derived from the program evaluation and review technique (PERT), the existing transport process is reengineered. Through the comparison of the costs before and after the transformation and the sensitivity analysis based on the reengineered process, it is determined that the reengineered process is superior to the initial process and exhibits strong practical guiding significance for logistics cost control and the development of China's automobile companies.

Pert using Fuzzy variables and probability distribution function randomly selected

Program Evaluation and Review Technique (PERT) is widely used for project management in real world applications. The aim of this paper is to simulate and analyze a PERT network under conditions of uncertainty though a hybrid model. The basic assumption is that a project under extreme conditions of uncertainty can be satisfactorily modelled by using simple fuzzy linguistic variables to estimate activities durations, and a probability distribution function randomly selected in order to measure the activity times. Fuzzy linguistic expressions are used to estimate the activity time. Activity parameters are calculated by using basic operations between triangular fuzzy numbers and centroid method with classical Beta PERT definition. For each activity time a probability distribution function is randomly selected from a set of four possible distributions commonly cited in the literature. Hypothetical projects with 4, 40, 400 and 4000 activities using the proposed model are analyzed; the project duration is estimated through Monte Carlo Simulation. Finally, results are analyzed and compared with classical Beta PERT technique.

Optimization of Project Scheduling Activities in Dynamic CPM and PERT Networks Using Genetic Algorithms

Projects consist of interconnected dimensions such as objective, time, resource and environment. Use of these dimensions in a controlled way and their effective scheduling brings the project success. Project scheduling process includes defining project activities, and estimation of time and resources to be used for the activities. At this point, the project resource-scheduling problems have begun to attract more attention after Program Evaluation and Review Technique (PERT) and Critical Path Method (CPM) are developed one after the other. However, complexity and difficulty of CPM and PERT processes led to the use of these techniques through artificial intelligence methods such as Genetic Algorithm (GA). In this study, an algorithm was proposed and developed, which determines critical path, critical activities and project completion duration by using GA, instead of CPM and PERT techniques used for network analysis within the scope of project management. The purpose of using GA was that these algorithms are an effective method for solution of complex optimization problems. Therefore, correct decisions can be made for implemented project activities by using obtained results. Thus, optimum results were obtained in a shorter time than the CPM and PERT techniques by using the model based on the dynamic algorithm. It is expected that this study will contribute to the performance field (time, speed, low error etc.) of other studies.

Sensitivity analysis in PERT networks: Does activity duration distribution matter?

Abstract The Program Evaluation and Review Technique (PERT) is a stochastic network technique developed in the late 1950s. The original model assumes PERT β distribution for the activity durations. Later on, this was criticized by many researchers, and several new distribution types have been introduced, which were believed to be better in modelling the real activity duration distributions or were easier to handle from a mathematical point of view. Introduction of new activity duration distributions was criticized even by Clark—one of the pioneers of PERT—while other researchers were arguing that these new activity distributions could better describe the stochastic distributions of the activity durations and their application helps define the distribution of project duration better. In the course of our research, we have investigated the effect of various activity duration distribution types (PERT-beta, uniform, triangular, lognormal) on the project duration, as well as the impact of the inaccuracy of the activity durations' estimation when performing the PERT three-point estimation. Our basic assumption—that the differences in the distribution of the project duration caused by using different activity duration distributions are not considerable compared to the differences caused by the inaccuracy of the three-point estimations—has been tested on several hypothetical projects and case studies. Four different distributions have been applied, one at a time. The aim has been to clearly show the differences between the results of the application of the selected distributions, therefore the distributions have not been mixed. Monte Carlo analysis has been used to create the probabilistic distributions of the projects. All example projects have proved the basic assumption to be true. The results suggest that from a practical point of view, the accuracy of the three-point estimation is more important than the type of the activity duration distribution. Consequently, the selected activity duration distribution is essentially insignificant. The most important practical consequence of this research is that instead of the time-consuming and costly process of selecting the proper activity duration distributions, planners should devote more effort to adequately determine the activity durations.

Effects of the application of activity calendars on the distribution of project duration in PERT networks

The Program Evaluation and Review Technique (PERT) has been criticized for the proposed (beta) distribution of the activities, the three-point estimation method, the assumption of task independence and the assumed distribution of the project duration since its birth. Developments and generalizations of the succeeding years and decades were mostly aimed at resolving these issues. However, there are still pending questions that have not been examined in detail, if at all. One of these issues is the effect of activity calendars on the distribution of the project duration. Using a simple artificially created project we prove that the application of activity calendars has a greater influence on the distribution of the project duration than any of the above-mentioned criticisms. In the absence of analytic solutions, a robust tool performing Monte Carlo simulations has been used for calculations. • Gives a comprehensive survey about the most important critiques of PERT • Gives a comprehensive survey about the most important developments of PERT • Shows the effects of activity calendars on distribution of the project duration • Opens new gateways to the research of PERT

Ant colony optimization algorithm for stochastic project crashing problem in PERT networks using MC simulation

This paper describes a new approach based on ant colony optimization (ACO) metaheuristic and Monte Carlo (MC) simulation technique, for project crashing problem (PCP) under uncertainties. To our knowledge, this is the first application of ACO technique for the stochastic project crashing problem (SPCP), in the published literature. A confidence-level-based approach has been proposed for SPCP in program evaluation and review technique (PERT) type networks, where activities are subjected to discrete cost functions and assumed to be exponentially distributed. The objective of the proposed model is to optimally improve the project completion probability in a prespecified due date based on a predefined probability. In order to solve the constructed model, we apply the ACO algorithm and path criticality index, together. The proposed approach applies the path criticality concept in order to select the most critical path by using MC simulation technique. Then, the developed ACO is used to solve a nonlinear integer mathematical programming for selected path. In order to demonstrate the model effectiveness, a large scale illustrative example has been presented and several computational experiments are conducted to determine the appropriate levels of ACO parameters, which lead to the accurate results with reasonable computational time. Finally, a comparative study has been conducted to validate the ACO approach, using several randomly generated problems.

Fuzzy Linguistic PERT

<para xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> A model for Program Evaluation and Review Technique (PERT) under fuzzy linguistic contexts is introduced. In this fuzzy linguistic PERT network model, each activity duration is represented by a fuzzy linguistic description. Aggregation and comparison of the estimated linguistic expectations of activity durations are manipulated by the techniques of computing with words (CW). To provide suitable contexts for this purpose, we first introduce several variations of basic linguistic labels of a linguistic variable, such as weighted linguistic labels, generalized linguistic labels and weighted generalized linguistic labels etc., and then based on the notion of canonical characteristic value (CCV) function of a linguistic variable, we develop some related CW techniques for aggregation and comparison of these linguistic labels. Afterward, using a computing technique of linguistic probability introduced by Zadeh and based on the new developed CW techniques for weighted generalized linguistic labels, we investigate the associated linguistic expectation PERT network of a fuzzy linguistic PERT network. Also, throughout the paper, several examples are used to illustrate related notions and applications. </para>

Crashing PERT networks using mathematical programming

The paper introduces and develops a method for investigating the application of mathematical programming to the concept of crashing in Program Evaluation and Review Technique (PERT). The main objective is the minimization of the pessimistic time estimate in PERT networks by investing additional amounts of money in the activities on the critical path. The constructed mathematical model, which is built in terms of additional amounts of money that must be invested, shows that minimizing the pessimistic time decreases project duration and, at the same time, reduces its variance. The result of applying the model showed that the probability of realizing the terminal node is increased.

Stochastic gradient-based time-cost tradeoffs in PERT networks using simulation

Infinitesimal perturbation analysis and score function gradient estimators are developed for PERT (Program Evaluation and Review Technique) networks and analyzed for potential use for prescriptive project management. In particular, a stochastic version of the familiar deterministic “project crashing” problem is considered. A heuristic using the gradient estimators is developed and shown to give close to locally optimal performance relatively quickly. An attempt is made to characterize the amount of variability in networks that would warrant the use of this heuristic by comparing its performance experimentally to that of the standard linear programming approach using only the task means (ignoring variability).

An Engineer’s Introduction to PERT Scheduling and Control

Program Evaluation and Review Technique (PERT) is a method of planning work, comparing status with schedule, and evaluating progress at all levels of management in order to better control a major, complex, engineering project. PERT/COST adds control of manpower and funds. Three time estimates—optimistic, most likely, and pessimistic—are combined to obtain an expected time for completing each activity. The PERT network shows interdependencies of activities. An important result of the PERT calculations is the determination of the critical and slack paths of the network.