Papers by Amirhossein Amiri
Journal of Industrial and Systems Engineering, Jun 22, 2017
This paper proposes a multi-objective model for the economic-statistical design of the variable s... more This paper proposes a multi-objective model for the economic-statistical design of the variable sample size and sampling interval multivariate exponentially weighted moving average control chart by using double warning lines. The Markov chain approach is used to obtain the statistical properties. We extend the Lorenzen and Vance cost function considering multiple assignable causes and multivariate Taguchi loss approach to obtain the expected cost per time unit. The meta-heuristic nondominated sorting genetic algorithm is used to search for the Pareto optimal solutions. A numerical example is provided to illustrate the solution procedure. Finally, sensitivity analyses for some parameters are given.
Scientia Iranica, Sep 4, 2017
In some processes, quality of a product should be characterized by functional relationships betwe... more In some processes, quality of a product should be characterized by functional relationships between response variables and a signal factor. Hence, the traditional methods cannot be used to nd the optimum solution. In this paper, we propose a method, which considers two di erent dispersion e ects in domain and between replicates variations in the functional responses. Besides, we propose an integral based measure to nd the deviation from target function. A probabilistic method is applied to consider the correlation structure of functional responses. Three numerical examples and a real case from literature are studied to show the e ciency of the proposed method.
Journal of Industrial and Systems Engineering, Mar 6, 2020
An essential tool for examining the quality of manufactured products is acceptance sampling. This... more An essential tool for examining the quality of manufactured products is acceptance sampling. This research applies the concept of minimum angle method to extend two variables sampling plans including the variables multiple dependent state (VMDS) sampling plan and the variables repetitive group sampling (VRGS) plan on the basis of the process yield index Spk. Optimal parameters of acceptance sampling plans can be determined by solving a nonlinear optimization model with the following conditions: 1) The objective function of the plan is to minimize the average sample number. 2) Constraints are set in a way that the compliance rate will be satisfied with the ideal operating characteristic (OC) curve as well as the producer's and costumer's risks. The assessment of the proposed plans reveals that by increasing the rate of convergence to the ideal OC curve, the proposed VRGS plan performs better than the proposed VMDS plan in terms of the average sample number. A numerical example is considered to reveal the applicability of the proposed acceptance sampling plans.
employed with the PCA method are the Hotelling 𝑻 𝟐 statistic which are used for monitoring the pr... more employed with the PCA method are the Hotelling 𝑻 𝟐 statistic which are used for monitoring the process which is reduced by PCA. This study has two steps; first, the high dimensional process is reduced by applying PCA, and then, the reduced process is monitored.
International journal of engineering. Transactions B: Applications, 2023
Many problems do not have one or more variables that determine quality characteristics. In these ... more Many problems do not have one or more variables that determine quality characteristics. In these situations, as a solution method, a profile is descibed by linking independent variables to the response variable. One of the common assumptions in most monitoring schemes is the assumption of independent residuals. Contravention of this assumption can lead to misleading results of the control chart. On the other hand, when the data are contaminated, the classical methods of estimating the parameters do not perform well. Such situations require robust estimation methods. Hence, this paper proposes a robust method to estimate the process parameters for Phase I monitoring autocorrelated multiple linear profiles. The developed control chart is appraised in the absence and presence of contaminated data through comprehensive simulation studies. The results showed that the robust estimator decreases the impact of contaminated data on the performance of the proposed control chart for all outlier percentages and shift magnitudes. Generally, in all three scenarios, including outliers in the model parameters and error variance, the robust approach performs better than the comparative method.
N owadays, protecting sensitive resources is one of the most important issues by government polit... more N owadays, protecting sensitive resources is one of the most important issues by government politics. So, it is essential that government, in order to achieve this target, utilizes beneficial strategies. In this paper, investment optimization for the protection of sensitive systems has been investigated. Defender minimizes the expected damage with respect to budget and area restrictions of defense equipment. However, the attacker maximizes the expected damage of sensitive targets with respect to cost and weight restrictions of attack equipment. Besides, defender deploys false elements to reduce the probability of system and real target vulnerability. False and real elements cannot be distinguished by the attacker. But the attacker has some probability of successfully detecting false targets. The aim of this study is to determine the optimal strategies for defense of sensitive targets considering probability of a successful attack, attacker capability in detecting false targets, reliability block diagram and game theory approach. Finally, the presented model is illustrated for the case study and final findings are analyzed.
Communications in Statistics - Theory and Methods
One approach to detecting abnormality in social networks is defining the normal behavior of socia... more One approach to detecting abnormality in social networks is defining the normal behavior of social actors with the statistical models and then monitor the deviation of parameters of such models from what is expected. In this article, we assume Zero inflation Poisson regression as an underlying distribution to model the interactions between social actors. One kind of abnormality happens when a subgroup of the edges changes such that every edge has an irregular evolution. Fraudulent usually cooperate with each other to show their behavior normal. To monitor this kind of abnormality in social networks based on ZIP model in phase I, we propose a test based on Likelihood Ratio. The performance of our proposed method is investigated using simulation.
Scientia Iranica
Acceptance sampling plan has been extensively used in batch sentencing to provide the manufacture... more Acceptance sampling plan has been extensively used in batch sentencing to provide the manufacturer and the customer a general benchmark to meet their predetermined needs on the batch quality. This paper develops a flexible sampling procedure, based on the S pkA index, for simple linear profiles by switching inspection rules. The plan parameters of the two suggested types of quick switching sampling (QSS) systems, satisfying the desirable quality levels and constraining the manufacturer's and the customer's risks, are derived by solving an optimization model. The comparisons between the suggested systems and the existing sampling plans are discussed, in terms of the discriminatory power and the average sample number to show the better performance of the suggested systems. Finally, the suggested QSS systems are applied in the electronics industry.
In this paper, a multivariate control chart for detecting increasing shifts in coefficient of var... more In this paper, a multivariate control chart for detecting increasing shifts in coefficient of variation considering measurement errors in Phase II is developed. The proposed control chart is designed based on Markov chain approach and the average of run length (ARL) criterion. Sensitivity analyses are performed on the different parameters and the effect of measurement errors on the control chart performance is investigated. Also, the multiple measurement approach is applied to decrease the negative effect of measurement errors.
Today, most manufacturing processes include several stages. Hence, quality of final product depen... more Today, most manufacturing processes include several stages. Hence, quality of final product depends on quality of the entire manufacturing process. In these processes, any changes in quality characteristics in each stage affect quality characteristics in the following stages. This feature is referred to cascade property. One of the most applicable control charts to monitor the multistage processes is cause selecting (CSC) control chart that removes the effect of cascade property. In this paper, a two stage process with correlated multivariate-attribute quality characteristics is considered. To transform the distribution of the attribute quality characteristic to normal distribution, root transformation method is utilized. Then, an exponentially weighted moving average (EWMA) control chart based on discriminant analysis (DA) statistic is proposed as CSC control chart to monitor the quality characteristics in the second stage. The performance of the proposed method is compared with a ...
Journal of Industrial and Systems Engineering, 2016
The Taguchi method is a useful technique to improve the performance of products or processes at a... more The Taguchi method is a useful technique to improve the performance of products or processes at a lower cost and in less time. This procedure can be categorized in the static and dynamic quality characteristics. The optimization of multiple responses has received increasing attention over the last few years in many manufacturing organizations. Several approaches dealing with multiple static quality characteristic problems have been reported in the literature. However, little attention has been made on optimizing the multiple dynamic quality characteristics. In this paper, we investigate multivariate signal response systems (Dynamic Taguchi) and propose a method based on multivariate process capability. Simulated data shows that the proposed method can increase robustness of dynamic Taguchi method. Furthermore, proposed method is capable to find the optimal value of controllable factors in a continuous space.
Journal of Industrial and Systems Engineering, 2020
An essential tool for examining the quality of manufactured products is acceptance sampling. This... more An essential tool for examining the quality of manufactured products is acceptance sampling. This research applies the concept of minimum angle method to extend two variables sampling plans including the variables multiple dependent state (VMDS) sampling plan and the variables repetitive group sampling (VRGS) plan on the basis of the process yield index Spk. Optimal parameters of acceptance sampling plans can be determined by solving a non-linear optimization model with the following conditions: 1) The objective function of the plan is to minimize the average sample number. 2) Constraints are set in a way that the compliance rate will be satisfied with the ideal operating characteristic (OC) curve as well as the producer’s and costumer’s risks. The assessment of the proposed plans reveals that by increasing the rate of convergence to the ideal OC curve, the proposed VRGS plan performs better than the proposed VMDS plan in terms of the average sample number. A numerical example is co...
Usually real time of changes in process (change point) is different from the time control charts ... more Usually real time of changes in process (change point) is different from the time control charts alarm the process is out-of-control. Finding the change point in the process saves time and money to find out root causes of the problem in the process. This paper specifically assumes that quality of process is modeled by using an AR(1) autocorrelated simple linear profile. Then, the step change point in the regression parameters is estimated by using maximum likelihood method after getting a signal from the T 2 hotelling control chart in Phase II. Performance of the proposed method is evaluated by using simulation studies. Simulation results show that the accuracy and precision of the proposed method in a step change point estimation is acceptable and the results of estimation close to actual change point under both weak and strong autocorrelation as the magnitude of shifts increases.
A novel procedure to improve traditional EWMA control chart performance in detecting both small and large shifts
International Journal of Productivity and Quality Management, 2021
Scientia Iranica, Sep 4, 2017
In some processes, quality of a product should be characterized by functional relationships betwe... more In some processes, quality of a product should be characterized by functional relationships between response variables and a signal factor. Hence, the traditional methods cannot be used to nd the optimum solution. In this paper, we propose a method, which considers two di erent dispersion e ects in domain and between replicates variations in the functional responses. Besides, we propose an integral based measure to nd the deviation from target function. A probabilistic method is applied to consider the correlation structure of functional responses. Three numerical examples and a real case from literature are studied to show the e ciency of the proposed method.
International Journal of Engineering, 2015
A profile is a relationship between a response variable and one or more independent variables tha... more A profile is a relationship between a response variable and one or more independent variables that can describe the quality of a process or product. On the other hand, for an in-control process, capability indices are criteria for process quality improvement that allows meeting customer expectations. Although a considerable number of applications and monitoring methods have been already proposed for profiles, a few researches have focused on the process capability index of profiles. In this paper, we propose a new Spmk index to measure process capability when the quality of process is characterized by a logistic regression profile. In addition, we present an approximate (1- )100% confidence interval based on percentile bootstrap method. The performance of the proposed index and corresponding confidence interval is evaluated through simulation studies. The result shows that when the number of observations in each level increases the index performs better. Furthermore, increasing number of levels leads to improving precision of the proposed index. Also, the coverage rates of the confidence intervals are greater than 93.6% lower limit of the stated nominal in most cases. Finally, the application of the proposed index is illustrated through a real case.
Lecture Notes in Engineering and Computer Science, 2011
Abstract—In some real case problems, a relationship between a response variable and one or more e... more Abstract—In some real case problems, a relationship between a response variable and one or more explanatory variables called as profile is desirable to be monitored over time instead of the response variable itself. There are many techniques in the literature for monitoring the profiles. A special case of the profiles is where the response variable follows a binomial distribution known as Logistic regression profile. In the logistic regression profile, a link function relates the mean of response variable to explanatory variables. There are ...
Proceedings of the World Congress on Engineering, 2011
Abstract—In most optimization problems of an M/M/K queuing model with priority, the scenarios are... more Abstract—In most optimization problems of an M/M/K queuing model with priority, the scenarios are defined and optimized separately. However, sometimes, the scenarios are dependent and should be optimized simultaneously. In this paper, an efficient approach is developed for this purpose. The performance of the proposed approach is evaluated through a real case study in a ware house of a Gear Box production factory. Key words—Queuing model, Optimization, M/M/K with priority
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Papers by Amirhossein Amiri