Journal of Quality Engineering and Management

Abstract Digital transformation, large amount of data, and high speed of production processes are among the most important characteristics of the ecosystem of the fourth industrial revolution. These characteristics have influenced the decision-making processes of business managers. In the fourth industrial revolution, all elements of business and production systems, including decision support systems, will be affected by digitization and the high speed and accuracy of new technologies. One of these important pillars is quality management. Digitized quality management is called the Quality 4. Design of experiments as an active approach in quality management plays an important role in improving the quality of products and even processes. This powerful tool has been influenced by the changes that occurred in the fourth industrial revolution and has tended towards the design of intelligent experiments. This research aims to show with a comprehensive review in the literature how the design of experiments can provide a special role in meeting the requirements of customers in the fourth industrial revolution and the fourth quality. In this research, firstly, the changes made in the methods and design plans of the experiments, then the possible changes in the activities of the basic process of the implementation of the design of the experiments have been redefined according to the effects of new technologies. At the end, suggestions for future research have been proposed.

Abstract One of the most practical methods of monitoring and controlling project performance is earned value management. The widespread use of this method in many projects leads to the production of multiple indicators with mutual influence, This important feature makes their individual analysis with errors. In this method, not only the mutual influence of the indicators is not paid attention to, but also the lack of attention to the monitoring of the variability of the indicators has caused this method to monitor the project based on the criterion of indexability. In this research, using multivariable control charts, we have simultaneously checked the performance indicators of a gas supply project based on real data. After analyzing the obtained results, we have compared the performance of Hotelling and (MEWMA) charts with each other. After comparison, it was found that MEWMA chart has more capability and sensitivity than Hotelling chart in identifying changes in multivariate processes.

Abstract Today, degradation analysis is one of the most important approaches in evaluating the reliability of multi-component systems. As it is clear, improving the performance of real systems requires the use of efficient and predictable approaches to analyze degradation with considering the interaction of system degradation processes on each other. The literature review shows that degradation analysis of multi-component systems has been investigated in various researches, but the approach in which there is a profile relationship between the degradation processes of the system components has not been considered so far. When there is a functional relationship between the degradation processes of one or more components, it is called a profile in the statistical process control literature. The aim of this study is to provide an efficient approach to predict and evaluate the variability of degradation processes in the presence of multivariate profiles under the conditions of stochastic dependence. In fact, the proposed approach offers the possibility of predicting and evaluating the variability of degradation processes at the component and system level. In this paper, in order to evaluate the proposed approach, the data set of a multi-component system with a structure of 2 out of 3 has been used. The results show the effectiveness of the proposed approach.

Abstract Compressive strength is one of the important properties of concrete, which is affected by factors such as humidity, water-cement ratio, cement composition, aggregate dimensions, and age of concrete. All cases except age can be controlled by making changes in the mixing plan, therefore, in this research, the relationship between age and compressive strength of concrete has been investigated using profile analysis in a 6-story building construction project by concrete quality control experts. In this research, 10 concrete samples were processed in laboratory conditions after preparation, and the compressive strength of the samples was checked by 3 experts and each expert checked each sample 3 times. In the zero phase, with the Gage study method, the data is not affected by the measurement error. In phase one, by using the Storr and Braille control chart, out-of-control profiles have been removed, and a model has been presented to estimate the compressive strength of concrete according to the age of the sample. In the second phase, using 10,000 data simulated by MATLAB software, the performance of the model has been examined using the (EWMA) chart, the results show that the EWMA chart is able to identify out-of-control signals by applying changes in the model parameters An out-of-control signal can be a warning for signs such as cracking, cracking, sanding, and discoloration at older ages of concrete. Therefore, managers and concrete quality control experts can predict the factors of concrete destruction and take measures to restore concrete without spending a lot of money.

Abstract  In this research, in order to allocate reliability to the subsystems of a cube satellite in the conceptual design phase-with the objective of achieving a 73% reliability-we have developed. The target feasibility method as our research fundamental procedure. In no research study in the area of reliability allocation conducted so far have we found a method which has developed the technology factor or considered the relationships between suppliers and the issue of reliability allocation.  Therefore, the current research study focuses on the exact calculations of the technology factor. In order to estimate the letter factor, a concept designated as technology preparation assessment and another one as level of suppliers technological capacities are being discussed. In this regard, a model has been presented which is a synthesis of the letter two concepts.  The obtained results indicate that the reliability allocation through by adopting this methodology is a great help toward identifying critical subsystems and heir improvement at the design stage .