Journal of Quality Engineering and Management

Abstract In helicopter design, determining the geometric shape of the fuselage is one of the main and primary issues that affect the performance characteristics of the helicopter. The aerodynamic coefficients of the helicopter fuselage are the main criteria for determining the quality and appropriateness of the geometric shape of the helicopter fuselage. Optimal design of helicopter body geometry is a complex activity and it is necessary to determine the effects of different parameters of helicopter geometry on aerodynamic coefficients. In this paper, design of computer experiments based on simulation of computational fluid dynamics to study the effects of the main parameters of the helicopter body geometry, such as ratio of largest helicopter body width to helicopter length, ratio of largest helicopter body height to helicopter length and nose to radius of curvature radius ratio The fuselage is based on the aerodynamic coefficients of drag, lift and torsional torque. The experiments are based on Taguchi's orthogonal array L25 (53). To determine the relationship between aerodynamic coefficients and parameters of the geometric shape of the helicopter fuselage and the importance of each parameter in aerodynamic coefficients, three-dimensional procedure diagrams, signal to noise ratios, mean of main effects, response procedure methodology and analysis of variance were used. Also, mathematical models were developed to estimate the aerodynamic coefficients of drag, lift and torsional torque through the response procedure methodology. The results at 95% confidence level show that the most effective parameter in the value of the helicopter body drag coefficient is the ratio of the largest height of the helicopter body to the length of the helicopter and in the lift and torsional torque parameters is the ratio of the largest width of the helicopter to the length of the helicopter.

Abstract Abstract Control charts are used in process monitoring to identify any changes that may affect process quality. In many cases, it is assumed that the process data has a normal distribution, which may not be the case in practice. In this paper, we examine the economic statistical design of the   X ̅ control diagram when the qualitative characteristic distribution is not normal with the Markov chain approach. In this regard, we use the distribution as a model for the variable distribution of process quality. Due to the flexibility of its components, this distribution can model many distributions, including the normal distribution. We also show the design performance by analyzing the sensitivity of process parameters and based on the values ​​of skewness and elongation of the community, using genetic algorithm, for industrial application. 

Abstract Abstract Quality control tools are widely used in monitoring production processes. Quality monitoring of various production processes, from one-step processes to complex multi-stage processes in the first and second phases of control has been the focus of researchers. In recent decades, the use of quality monitoring tools in health care processes has also increased significantly. In contrast to the many efforts that have been made to monitor the quality of single-stage surgeries, researchers have not paid much attention to multi-stage surgeries. In this study, we have tried to enter the medical services space, while using the logistics model to mitigate the risk, monitor the two-stage process of thyroid cancer surgery for a set of 94 data and present our predictive model.

Abstract Reliability and safety of any system is the most important quality characteristic of a system. This qualitative characteristic is of special importance in systems whose operation is under various stresses such as: high temperature, high speed, high pressure, etc. A noteworthy point that is often not taken into account in calculating the reliability and safety of systems is the existence of interdependencies between subsystems with each other, which causes different failures in the system. One of the most important of these failures is common cause failure. In this type of failure, several subsystems or all subsystems fail simultaneously or in a short period of time due to a common cause. Failure to consider common cause failures in calculating the reliability of systems leads to an optimistic estimate of the reliability rate of the system and consequently leads to overconfidence in the system. In this paper, first using the product structure separation techniques (PBS), performance flow block diagram (FFBD) to identify and then using the reliability block diagram (RBD) to calculate and allocate the output reliability of a dynamic positioning system that includes hydraulic thrusters And electric for the movements of roll, suge, sui, yaw and hyo, will be discussed.In calculating the reliability of the system with the help of cascade failure probability rules and with the help of beta factor model and PDS method, common cause failures of different subsystems were considered.

Abstract In today's highly competitive business environment, the main approach of all business activities is to optimally meet the needs of customers and gain their satisfaction and trust. Life insurance services is one of the areas of the insurance industry that has a very close and very dynamic relationship with customers. In this regard, the use of techniques such as quality performance enhancement (QFD) can be an important step towards achieving an appropriate level of service quality and customer satisfaction. QFD is a systematic way to make the right connection between customer needs and service or product features. In this article, first, 30 customer requests for life insurance services in three provinces of Tehran, Yazd and Semnan are identified, and their importance is determined by distributing a questionnaire among 270 customers. Then, with the formation of a quality house, the necessary activities and corrective measures in order to meet the demands are identified and weighed. Finally, a mathematical model is proposed to consider the budget constraints in the decision-making process. In addition, the theory of triangular fuzzy numbers is used throughout the research method. The obtained results can provide practical and useful information to the decision makers of life insurance services in the country.

Abstract In recent years, due to increasing environmental concerns, government regulations and natural resource constraints, and the impact of green laws, the closed-loop supply chain has attracted increasing attention. Since the supplier has an important role in the supply chain, if faced with risk and disruption, it will have detrimental and important effects on the supply chain, so it seems necessary to study these conditions. Therefore, in this paper, the issue of closed-loop supply chain network design in supply risk conditions is investigated. In addition to disruption of supply, factors such as the use of excess inventory as well as contracts with reliable suppliers in periods that we have not disrupted are considered flexibility strategies in this article. The goal is to minimize chain costs with respect to location decisions, flow between levels, and lost sales. Disruption in suppliers is considered in different scenarios and in detail. The problem is modeled using mixed integer programming and a possible two-step approach is used to consider the uncertainties in the proposed model. At the end, sensitivity analysis is performed on the proposed model and suggestions are provided for using this model in the real world.