Journal of Quality Engineering and Management

Abstract   The objective of this research is to provide a rich picture of current issues of the company and a conceptual model along the seven steps of SSM model in the field of quality management. Soft system methodology is a tool based on the philosophy of soft operational research that has been used to formulate and manage complex problems. Investigating the effect of this technique is a significant contribution to continuous improvement in competitive environments. Therefore, the present study attempts to implement this model in one of the food industries. It seems that the use of soft operational research techniques along with other tools and approaches of total quality management, in organizations that consider quality as an important and strategic issue, help practitioners in this field. The findings indicate that in the studied company strategy formulation is not well-performed according to the company vision. Also, the inappropriate cooperation and involvement of the staff in formulating the strategies, inappropriate support of staff innovation as well as the inappropriate rewards system, lack of effective communication with the customers and partners, changes in the foreign currency, and the problems of refining with the suppliers and contractors are among the issues in the studied company.

Abstract Purpose: This study aims to provide a comprehensive and accurate assessment of Iran's overall quality status in 2023 across six key dimensions: economy, technology, infrastructure, education, healthcare, and environment. The research also seeks to determine Iran's global ranking and offer insights for future improvement.
Methodology: Key indicators within each dimension were analyzed and weighted using Shannon entropy. The six individual quality indices were then aggregated to construct a single, unified national quality index.
Findings: Iran's overall quality index was estimated at 0.449, below the global average of 0.53, ranking 72nd out of 130 countries. While Iran performs close to the worldwide average in most dimensions, its infrastructure index falls significantly short.
Originality/Value: This study is among the first to apply a multidimensional index of national quality constructed using Shannon entropy. It provides a quantitative and practical framework that highlights Iran's strengths and weaknesses, supporting evidence-based policy planning.

Abstract Quality of service is the distinguishing factor and the most powerful competitive weapon that many service organizations such as hospitals have. The purpose of this study was to rank selected hospitals in Iran in terms of service quality using a combination of SERVQUAL methods and data envelopment analysis. In this study, first, a systematic search in various scientific databases, to find the research conducted to assess the quality of services provided in Iranian hospitals using the SERVQUAL model, which found 22 related studies. Then, with the help of data envelopment analysis method and considering the five dimensions of service quality as its outputs and considering hospitals as decision-making units by DEAP 2.1 software, the scores related to each were calculated. Most of the published researches were related to 2016 in terms of time and related to Tehran province in terms of location. Zabol Shahid Elmi Field Hospital with a score of 1.000 and D Hospital affiliated to Qazvin University of Medical Sciences with a score of 0.364 won the first and last ranks, respectively. The average score of all hospitals was 0.796. Scores calculated by data envelopment analysis showed that there is an average increase of 20.4% in the quality of hospital services. Also, Shahid Elmi Field Hospital in Zabol can be considered a model for other hospitals under study due to its superior ranking.

Abstract One of the most important tools for statistical process control is the control chart. The construction of control diagrams is achieved by determining the design parameters of the sample size, sampling distance and coefficient of control limits. Statistical-economic design is the best way to determine these parameters by considering statistical properties and cost. Statistical design - Economics Control charts require a distribution for the process failure mechanism. The most popular distributions in the analysis of the failure mechanism of the exponential distribution process are gamma and Weibull. Recently, a new distribution called generalized exponential distribution has been added to conventional distributions in data life analysis and process failure mechanisms. If the failure mechanism data follows this distribution, the use of other distributions will give users misleading and inaccurate results. On the other hand, a fundamental assumption in most control charts is the independence of process-related observations; But in practice we have situations with correlated data. As a result, it is of particular importance to identify control charts that can be used to control such data.In this paper, statistical-economic design of control charts with correlated data under generalized shockwave and Weibull models and by providing a numerical example , We show their application. We have applied a sensitivity analysis to investigate the effect of changing the controlled properties of the first type error rate, power and correlation coefficient. The results show that this type of control charts have undesirable statistical properties and the limitation on the first type of error has a significant effect on determining the average cost per unit time and design parameters. Also, the correlation coefficient is indirectly related to the sample size and sampling distance and is directly related to the average cost per unit time.

Abstract  Different types of process control methods exist for jointly monitoring of several quality characteristic. Recent studies have shown that multi-stage sampling control charts perform better in detecting shifts in process. Therefore, because of the efficiency of the joint mean and standard deviation charts with multi-stage sampling in detecting shifts in mean and standard deviation of the process, discussion and consideration of these charts is necessary. In this paper, the joint Double Sampling and Triple Sampling mean and standard deviation charts are introduced. The joint Statistical Design of these charts is formulated as an optimization problem and solved using a genetic algorithm. 
 
 

Abstract Traditional control diagrams are based on the basic assumption that process data are sequentially independent of each other and have a normal distribution. However, in many cases in the real world, including in chemical and continuous processes, this assumption does not exist and there is a kind of autocorrelation between the data collected from the process. The use of traditional control charts in self-correlated processes is unreliable and increases erroneous warnings. One of the methods developed to control autocorrelation processes is to identify the structure of process time series and use residual values ​​to control process. In this paper, a model based on adaptive neural-fuzzy systems to identify time series structure and predict design use. May be. Is in AR (2). Also, the residual control diagrams based on this system for the self-return data of degree 2 and for (EWMA) finally using the simulated data, the efficiency of the proposed method in the moving average diagram are evaluated. Different degrees of correlation are evaluated.

Abstract The design of the closed loop supply chain network is one of the most important and fundamental strategic decisions, with the proper design of which creates a desirable structure and facilitates the efficient management of the chain effectively. One of the most fundamental problems in the design of the supply chain network is the closed loop of uncertainty in the quality of the return products, due to the emergence of this problem, the lack of accurate and accurate information as well as the dynamics and complexity of the chain components. This research in the design space the closed loop supply chain network is for durable products, which in the short term cannot be damaged and allow the reuse of parts in the production of new products, recycling or sales on the secondary market. The main purpose of this study is to use a two-stage randomized programming model and maximize expected earnings for all of the quality status scenarios in which the target function is a combination of revenue from the sale of products and recycled materials and components Recovered, in addition to fixed costs for centers, processes, logistics and transportation. Due to the complexity of the model, the problem was used with the Lp-shape and CPLEX algorithms and the GAMS software was used to solve the problem. Based on the results of the research, the substantive response introduced by CPLEX for the C3 to C6 test questions is significantly far from the optimal responses obtained by the L-Shape method. 

Abstract The purpose of this study is to provide a suitable model for advanced product quality planning at the level of defense organizations, so that all design-related requirements are considered seamlessly and consistently throughout the idea-to-product process. In this research, different models of advanced product quality planning were studied and based on the AIAG standard model [1], different models were compared and compared. Then, based on the knowledge of internal and external stakeholders of the design process, a list of their requirements was determined and based on that, the steps and documents of each model phase were selected and determined. Finally, the proposed model for six products was reviewed in the design offices and the conformity assessment was performed. According to the results of this research, the main problem of product quality planning in the design stage is the lack of full knowledge of stakeholders and their requirements.

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 CUSUM and EWMA, a change in process may cause the statistic to move away from the center. In this case, if another change occurs in the opposite direction, the chart needs more time to be warned. This is called the inertia effect. In this paper, the effect of inertia on the performance of non-parametric CUSUM and EWMA sign diagrams is investigated and the two diagrams are compared. To do this, a simulation program is developed that calculates the average length of the sequence in the controlled state (ARL0) and out of control (ARL1) in these diagrams for different parameter values ​​using three different distributions. The results of the simulation show that the values ​​of ARL0 in the CUSUM symbol are not affected by inertia, but the values ​​of ARL1 in the graph increase in large changes and the power of the graph in detecting these changes decreases. Also in the EWMA symbol chart, the ARL0 values ​​decrease and the ARL1 values ​​increase for medium and large changes. In other words, due to inertia in this chart, the number of false warnings increases and the power to detect changes decreases. Due to the less negative effect of inertia on the performance of the CUSUM signal diagram than EWMA, the use of this diagram in the control of abnormal processes is recommended.

Abstract  Among the factors responsible and involved in projects are quality control consulting services and resistance of building materials companies which are working to have an effective performance through interior fit with the structure of the projects as well as exterior fit with the environment. They are also working to complete the projects in the shortest possible time and cost and with the right and certain quality. This paper aims to show the position and significance of quality management in construction quality control companies and to prioritize criteria for successful quality management. In this regard, through literature review and interview with experts, a questionnaire with 33 variables and 7 indices was designed to rank quality management measures. Interacting with the managers and senior technical staff in consulting engineer companies finally 15 sub-indices were determined. The research community is composed of 22 companies associated with quality control process and resistance of building materials in Rasht. The sub-indices have been asked through paired comparison questionnaires. Findings were analyzed through fuzzy analytical hierarchy process (AHP) software and the criteria were prioritized. Then, the impact of the criteria on quality management of construction quality control companies was found. Training index and operational management process, among the indices, were identified as the most significant factors in quality management of construction consulting engineers companies.

Abstract In statistical quality control, the concentration and dispersion of continuous quality characteristics in a process are usually examined simultaneously with the help of two graphs. In this way, the changes in each will be identifiable simultaneously. Due to the high efficiency of control graphs of mean and standard deviation with double sampling in rapid identification of mean changes and standard deviation of the process, discussion of this category of graphs seems necessary. In this paper, based on the results of designing mean control and standard deviation diagrams with double sampling, mean and control standard deviation diagrams with triple sampling are introduced. Statistical design of mean control and standard deviation diagrams with triple sampling is formulated as an optimization problem and to solve this problem, genetic algorithm is proposed.

Abstract Purpose: Calculating the optimal target mean for a process is recognized as an essential research area, with many proposed models in the literature. Previous studies have typically focused on a single market. The main difference in this research lies in the number of markets considered; unlike previous works, this study examines n different markets simultaneously.
Methodology: This study aims to determine the optimal process quality mean for a limited number of markets based on the target values of quality characteristics in each market. We propose a model to calculate this optimal mean across n markets with different price/cost structures. A key innovation of this research is the incorporation of probability distributions that reflect the likelihood of the quality characteristic falling within specific quality ranges in each market.
Findings: The model considers the probability that the quality characteristic falls within each market's defined quality range. To analyze and solve the model, absorbing Markov chains are used. A numerical example is presented in which the model is applied to two markets, and the optimal target mean and corresponding optimal revenue are obtained.
Originality/Value: Based on the results from the numerical example, the optimal target mean and revenue were determined for the two markets. A sensitivity analysis was conducted to assess the influence of various model parameters on these parameters, demonstrating how changes in parameters impact the model's outcomes.

Abstract Nowadays, the process of producing most products is such that the products are created in different and interdependent stages. . One of the most widely used and specialized control charts used to monitor multi-stage processes is the selection diagrams of deviant agents. These control charts have been further developed and used for high quality characteristics. In this paper, two control diagrams based on generalized linear patterns are proposed to monitor a two-step process with a two-sentence qualitative characteristic in the second step. In the proposed approach for monitoring binomial variables, a cumulative sum control control diagram and a dual-balance moving average control diagram are designed considering the relationship between qualitative characteristics in two stages. The proposed control diagrams are based on the residual values ​​of the deviation. In order to establish the relationship between the qualitative characteristics of the first and second stages, a new interface function has been used in the framework of the generalized linear pattern. The performance of the proposed control diagrams is evaluated using simulation based on the average sequence length criterion. The results show that the ability to detect cumulative summand control charts and the proposed dual rhythmic moving average is far better than the control charts in the literature.

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 The real world energy sector is one of the most sophisticated systems that must be viewed in a holistic view. In this research, researchers have identified and analyzed the effective interactions of after-sales services in the Iranian LPG industry. Since post-sales services can be assessed on a variety of criteria, the Multi-criteria Decision Approach (MCDM) approach for such an analysis is a good approach. Due to the particular complexity of the liquid gas industry from the refinery to the end user's end, in this research, DEMATEL FUZZY is used to analyze internal interactions, and for the reader to have a deeper understanding of the subject, the causal diagrams (CLD) in the form of Dynamic Systems (DYNAMIC SYSTEM). After thorough review of the theoretical foundations and expertise, 17 industry-leading indicators of the post-sales service have been identified in this industry and 10 respondents have answered questions. In addition, the researchers express specific definitions of service in this industry. The results of the research show that reliability variables, representations, documents have the most impact, and improvement variables, responsiveness, timing of visits have the greatest interaction with other components in the model. Dynamic model also depicts the real world image of internal service interactions.

Abstract Purpose: In many industrial processes, there are situations where simultaneous monitoring and control of two or more dependent variables are necessary. In such cases, univariate control of quality characteristics can be misleading when considered independently. In the classical approach, when a quality characteristic falls outside the specified technical limits, the quality loss is regarded as a cost. All products within the technical limits of the quality characteristic are assumed to have similar quality, regardless of the deviation of the quality characteristic from its target value. However, it is essential to distinguish between products that fall within the technical limits of the quality characteristic, as any deviation from the target value incurs a proportional loss.
Methodology: This paper introduces, for the first time in the literature, a reflected normal loss function to determine the average cost of producing non-conforming products when two quality characteristics are evaluated. In summary, this study focuses on the statistical-economic design of a multivariate T²-Hotelling control chart with multivariate variable sampling intervals in the presence of a reflected normal multivariate loss function (RNLMVSIT²). Additionally, a sensitivity analysis is conducted to examine the effects of time and cost parameters on the design parameters and the average cost.
Findings: The results demonstrate the satisfactory performance of the proposed models.
Originality/Value: This paper introduces, for the first time in the literature, a reflected normal loss function to determine the average cost of producing non-conforming products when two quality characteristics are evaluated.

Abstract Reliability and accessibility are important features in most systems, especially electronic and mechanical systems, which are in the industries of air communication, Internet networks, telecommunication systems, power generation systems, production facilities, etc., which are among the most important reasons for increasing the complexity of systems. , Hardening and more sensitive market competitive environment, increasing production costs in the event of a stoppage, and so on. In this paper, inspired by research on the reliability and optimization of systems reliability, a model with multiple objective function is presented, the objective function of which includes accessibility optimization and cost of all systems, where the system includes both non-repairable components and Is repairable. In this model, system accessibility, in addition to allocating surplus components to subsystems, allocation of accessibility for components is also considered, which increases the flexibility of the model to increase the accessibility of systems. To solve the designed model, a genetic algorithm based on the arrangement of non-privileged solutions (NSGA-II) is used, which has a high power to solve such problems. Finally, a numerical example is presented to express the efficiency of the proposed model and the method of solving it. In this example, a system is considered in which part of its components is unrepairable and the other part is repairable.

Abstract The issue of performance of complex engineering systems in environments with high uncertainty is one of the topics of research in the field of device engineering. Uncertainties and hazards in unfamiliar environments significantly affect the value provided by complex engineering systems to its stakeholders. Therefore, empowering complex systems to operate in conditions of uncertainty is inevitable. Obviously, before taking any action to improve the design of these devices to achieve greater capability, it is necessary to determine the index and model to measure their capability in the face of uncertainty. In this study, which is a combination of qualitative, quantitative, applied and fundamental research methods in terms of the type of research; After reviewing the research records, biodegradability has been introduced as an indicator to evaluate the capability of complex engineering systems for operations in conditions of uncertainty. Operating environment and three-level modeling of the operating environment, product functions and physical equipment of the product are its key features. Finally, the applicability of the proposed model is shown through a case study of an imaging satellite as a complex engineering system. The accuracy of the proposed model has been confirmed based on the analysis of the results of the case study and a questionnaire completed by experts.

Abstract   One of the most important control charts is Shewhart  ̅ chart. This sampling technique has proven to be very effective in situations where measurments are difficult or expensive, but could inexpensively be ordered. This article investigated economic design and economic-statistical design of  ̅X control chart based on RSS. The numerical results are shown economic statistical design is better than economic design based on RSS. Since economic-statistical design is more reasonable than economic design based on RSS. The result is shown the cost of  economic-statistical design has been increased a bit more than economic design based on RSS .So, It is suggested to use economic- statistical design  ̅X    control chart for controling of services and industrial processes mean based on economic and statistical optimization features of  ̅X  control chart and the results paper.   

Abstract Equipment is usually damaged by a random pattern based on a gradual deterioration process. In these cases, the level of deterioration gradually increases, and when its value exceeds the predefined decline threshold, it is considered disabled. In addition, environmental disturbance factors such as temperature, humidity, pressure, etc. may experience uncontrollable changes and alter or accelerate failure patterns. Since estimating the remaining equipment life is very important in the effectiveness of forecast maintenance planning and this estimate should be based on identifying accelerated failure patterns, the present study is the first to estimate the remaining equipment life in the presence of effects. The accelerator is focused on two correlated disturbance factors and in it to monitor the environmental factors affecting the life of the equipment from control charts and how to meet the average residual life of the equipment in different conditions under control, out of control due to the first disturbance factor, Being out of control due to the second factor and being out of control due to both factors are presented. A numerical example is also provided to illustrate the details of the calculations.

Abstract In today's competitive market, many products are sold under the basic warranty, and in order to increase profit margins and customer satisfaction after the end of the basic warranty, manufacturers offer warranty extensions to customers at a specific price and time. In this research, the aim is to maximize the producer profit by determining the optimal values of product price, length of basic warranty period, length of warranty renewal, repair level in incomplete repair and amount of spare parts (for demand of products under basic warranty, warranty extension and out of warranty). . In order to better model the real situation, it is assumed that the product can be repaired with three types of minimum, incomplete and complete repairs at the time of failure, and the percentage of products that are repaired each time is also considered as a decision variable. have became. The product reliability function is modeled at the time of incomplete repair with the Kijima virtual life model approach. The problem-solving approach is based on the simulation-based optimization approach in three stages. In the first stage, decision variables such as product price, basic warranty period, warranty renewal period, warranty renewal price, repair level and the probability of what kind of repair each product It is determined by a meta-heuristic algorithm. Then, using Monte Carlo simulation, the number of products that have purchased the warranty extension and the number of product failures is calculated, and finally, the production of spare parts is optimized using a dynamic programming algorithm. This model has also been analyzed for LG vacuum cleaner product and Goldiran after-sales service. 

Abstract The aim of this study was to provide a model to explain the relationship between quality requirements and service quality dimensions in Iranian universities. The research method was descriptive survey and the statistical population included academic experts, managers and staff as well as customers of Islamic Azad universities in Fars province. Using purposive sampling method, 30 experts were selected and by stratified random sampling, 415 managers and employees and 464 customers were selected. Data collection tools were questionnaires of quality requirements and dimensions of service quality, which were developed by the researcher after studying the theoretical foundations and research background, and its validity and reliability were estimated and approved. To analyze the data, one-sample t-test and structural equation model were used with the help of AMOS software. The results showed that the status of quality requirements (M = 3.57) and the status of service quality dimensions (M = 3.19) are in a relatively desirable range, in other words, considering the significance level of α ≤ 0.05 and appropriate. Existence of fitness indicators This model can be used to determine the relationship between the components of quality requirements and dimensions of service quality in Islamic Azad universities of Fars province. Also, the research results showed that only professional obligation predicts the dimensions of service quality and moral, competitive and accountable obligation do not predict the dimensions of service quality.

Abstract Proper network design has many effects on the performance, efficiency and effectiveness of supply chains in achieving the expected goals and meeting the needs of customers. In this research, a multi-level multi-objective model for supply chain network design considering pricing, product quality level and disruption is presented. The cost of transporting each vehicle is assumed to be a dynamic random function rather than a parameter. Therefore, discrete-event simulation has been used to estimate transportation costs. Due to the important role of risk and disruption concepts in supply chain network design, risk minimization along with profit maximization according to pricing and quality concepts have been defined as objective functions. Supply chain demand is considered a linear function of price and quality level of products. Finally, the supply chain network design problem is solved by simulation, risk and price-dependent demand with NSGA-II algorithm and the results are validated by MOSA algorithm.

Abstract Today, manufacturers use warranty as an important advertising tool to increase market share. Offering the product to the market with a longer warranty, although attracting more customers, increases the manufacturer's costs. In the real world, manufacturers can provide buyers with an option to renew their warranty for a specified period of time after the end of the basic warranty period. Thus, products that do not renew their warranty as products out of warranty are the main source of profitability of the manufacturer from the sale of spare parts. In this research, a new model is presented that helps the manufacturer to increase profits and considering the level of customer satisfaction and the effect of selling spare parts to products out of warranty, such as pricing of the main product, length of basic warranty period, length of warranty renewal period. Optimize the price of the warranty extension. The developed particle swarm algorithm and the sports league algorithm have been used to solve the model. Due to the fact that Goldiran Company in Iran, as the after-sales service representative of LG, has provided the possibility of extending the basic warranty for products under this brand, the proposed model has been solved with data related to the LED product. The results show that Goldiran Company can help increase the producer profit margin by changing the values of the basic warranty period and extending the warranty according to the product life cycle and planning time, while now the company has fixed the warranty period and extended warranty period for all its products. is considered.