Seyed Taghi akhavan niaki
Professor, Department of Industrial Engineering, Sharif University of Technology, Tehran, Iran
[ 1 ] - Vendor Managed Inventory of a Supply Chain under Stochastic Demands
In this research, an integrated inventory problem is formulated for a single-vendor multiple-retailer supply chain that works according to the vendor managed inventory policy. The model is derived based on the economic order quantity in which shortages with penalty costs at the retailers` level is permitted. As predicting customer demand is the most important problem in inventory systems and th...
[ 2 ] - Phase-II Monitoring of AR (1) Autocorrelated Polynomial Profiles
In some statistical process control applications, quality of a process or product can be characterized by a relationship between a response and one or more independent variables, which is typically referred to a profile. In this paper, polynomial profiles are considered to monitor processes in which there is a first order autoregressive relation between the error terms in each profile. A remedi...
[ 3 ] - A New Uni-attribute Control Chart to Monitor the Number of Nonconformities
The most well-known uni-arribute control chart used to monitor the number of nonconformities per unit is the Shewhart type C-chart. In this paper, a new method is proposed in an attempt to reduce the false alarm rate in the C-chart. To do this, the decision on beliefs (DOB) concept is first uti [1] Corresponding author e-mail: [email protected] lized to design an iterative method, where...
[ 4 ] - An Integrated Model of Project Scheduling and Material Ordering: A Hybrid Simulated Annealing and Genetic Algorithm
This study aims to deal with a more realistic combined problem of project scheduling and material ordering. The goal is to minimize the total material holding and ordering costs by determining the starting time of activities along with material ordering schedules subject to some constraints. The problem is first mathematically modelled. Then a hybrid simulated annealing and genetic algorithm is...
[ 5 ] - A Comparative Study of Four Evolutionary Algorithms for Economic and Economic-Statistical Designs of MEWMA Control Charts
The multivariate exponentially weighted moving average (MEWMA) control chart is one of the best statistical control chart that are usually used to detect simultaneous small deviations on the mean of more than one cross-correlated quality characteristics. The economic design of MEWMA control charts involves solving a combinatorial optimization model that is composed of a nonlinear cost function ...
[ 6 ] - Absorbing Markov Chain Models to Determine Optimum Process Target Levels in Production Systems with Rework and Scrapping
In this paper, absorbing Markov chain models are developed to determine the optimum process mean levels for both a single-stage and a serial two-stage production system in which items are inspected for conformity with their specification limits. When the value of the quality characteristic of an item falls below a lower limit, the item is scrapped. If it falls above an upper limit, the item is ...
[ 7 ] - A Hybrid Meta-Heuristic Method to Optimize Bi-Objective Single Period Newsboy Problem with Fuzzy Cost and Incremental Discount
In this paper the real-world occurrence of the multiple-product multiple-constraint single period newsboy problem with two objectives, in which there is incremental discounts on the purchasing prices, is investigated. The constraints are the warehouse capacity and the batch forms of the order placements. The first objective of this problem is to find the order quantities such that the expected ...
[ 8 ] - A Review and Evaluation of Statistical Process Control Methods in Monitoring Process Mean and Variance Simultaneously
In this paper, first the available single charting methods, which have been proposed to detect simultaneous shifts in a single process mean and variance, are reviewed. Then, by designing proper simulation studies these methods are evaluated in terms of in-control and out-ofcontrol average run length criteria (ARL). The results of these simulation experiments show that the EWMA and EWMS methods ...
[ 9 ] - محاسبه تعداد و مکان بهینه مراکز مختلف جمع‌آوری خون در استان آذربایجان شرقی بر اساس مدلسازی ریاضی
چکیده سابقه و هدف در طراحی زنجیره تامین خون یکی از موضوعات کلیدی، تعیین محل مناسب مراکز جمع‌آوری خون است تا علاوه بر دسترسی آسان اهداکنندگان و نیز توزیع مناسب خون و فرآورده‌های خونی به مراکز بیمارستانی، هزینه‌های جمع‌آوری خون به حداقل رسانده شود. هدف از تحقیق حاضر، محاسبه تعداد و مکان بهینه مراکز تهیه و فرآوری، ثابت و سیار خونگیری بر مبنای تقاضای مراکز درمانی و هزینه‌های احداث و عملیاتی این م...
[ 10 ] - Vendor Managed Inventory of a Single-vendor Multiple-retailer Single-warehouse Supply Chain under Stochastic Demands
In this study, a vendor-managed inventory model is developed for a single-vendor multiple-retailer single-warehouse (SV-MR-SV) supply chain problem based on the economic order quantity in which demands are stochastic and follow a uniform probability distribution. In order to reduce holding costs and to help balanced on-hand inventory cost between the vendor and the retailers, it is assumed that...
[ 11 ] - A Markov Model to Determine Optimal Equipment Adjustment in Multi-stage Production Systems Considering Variable Cost
Our aim is to maximize expected profit per item of a multi-stage production system by determining best adjustment points of the equipments used based on technical product specifications defined by designer. In this system, the quality characteristics of items produced should be within lower and higher tolerance limits. When a quality characteristic of an item either falls beneath the lower li...
[ 12 ] - Presenting a stochastic multi choice goal programming model for reducing wastages and shortages of blood products at hospitals
One of the most fundamental components of healthcare system on each country is blood supply chain management. This chain is comprised of two significant components including collecting donor’ bloods and supplying blood’s products. The main purpose of this paper is to concentrate on supplying blood products and present a novel constrained bi-objective mathematical model for a two-echelon blood s...
[ 13 ] - A Multi-Stage Single-Machine Replacement Strategy Using Stochastic Dynamic Programming
In this paper, the single machine replacement problem is being modeled into the frameworks of stochastic dynamic programming and control threshold policy, where some properties of the optimal values of the control thresholds are derived. Using these properties and by minimizing a cost function, the optimal values of two control thresholds for the time between productions of two successive nonco...
[ 14 ] - A New Acceptance Sampling Plan Based on Cumulative Sums of Conforming Run-Lengths
In this article, a novel acceptance-sampling plan is proposed to decide whether to accept or reject a receiving batch of items. In this plan, the items in the receiving batch are inspected until a nonconforming item is found. When the sum of two consecutive values of the number of conforming items between two successive nonconforming items falls underneath of a lower control threshold, the batc...
[ 15 ] - تحلیل حساسیت در ریسک با استفاده از شبکه‌های بیزی
بررسی ریسک و بهبود ایمنی سیستم های امروزی به دلیل پیچیدگی های طراحی و عملکردی فراوان آنها، تحلیلی دشوار، پیچیده و هزینه بر است. معیارهای اهمیت در پایایی با شناسایی مهمترین اجزای تأثیرگذار در ایمنی سیستم، نقشی بسزا در افزایش سطح ایمنی سیستم و کاهش ریسک آن با صرف کمترین منابع ممکن را دارند. اما درخت خطا که ابزار پیاده سازی این معیارها است امکان مدل سازی بسیاری از پیچیدگی های سیستم های امروزی را ن...
[ 16 ] - Optimization of an energy based bi-objective multi skilled resource investment project scheduling problem
Growing concern in the management of energy due to the increasing energy costs, has forced managers to optimize the amount of energy required to provide products and services. This research integrates an energy-based resource investment project-scheduling problem (RIP) under a multi-skilled structure of the resources. The proposed energy based multi skilled resource investment problem (EB-MSRIP...
[ 17 ] - Resource Constrained Project Scheduling with Material Ordering: Two Hybridized Meta-Heuristic Approaches (TECHNICAL NOTE)
Resource constrained project scheduling problem (RCPSP) is mainly investigated with the objective of either minimizing project makespan or maximizing project net present value. However, when material planning plays a key role in a project, the existing models cannot help determining material ordering plans to minimize material costs. In this paper, the RCPSP incorporated with the material order...
[ 18 ] - Redundancy Allocation Problem of a System with Three-state Components: A Genetic Algorithm (RESEARCH NOTE)
The redundancy allocation is one of the most important and useful problems in system optimization, especially in electrical and mechanical systems. The object of this problem is to maximize system reliability or availability within a minimum operation cost. Many works have been proposed in this area so far to draw the problem near to real-world situations. While in classic models the system com...
[ 19 ] - A Novel Hybrid Approach to Analyze Cost of Quality: Balanced Scorecard and Fuzzy Logic
In this paper, a new methodology in the area of cost of quality (COQ) is proposed to determine the optimal investment allocation to all costs. The goal is to minimize costs involved in achieving a required level of quality. The contribution of this paper is fourfold: (I) considering two types of weights for each part of COQ, in which the first type is determined by the cost volume and the secon...
[ 20 ] - Monitoring and Change Point Estimation of AR(1) Autocorrelated Polynomial Profiles
In this paper, a remedial measure is first proposed to eliminate the effect of autocorrelation in phase-ІІ monitoring of autocorrelated polynomial profiles, where there is a first order autoregressive (AR(1)) relation between the error terms in each profile. Then, a control chart based on the generalized linear test (GLT) is proposed to monitor the coefficients of polynomial profiles and an R-c...
[ 21 ] - Bayes Interval Estimation on the Parameters of the Weibull Distribution for Complete and Censored Tests
A method for constructing confidence intervals on parameters of a continuous probability distribution is developed in this paper. The objective is to present a model for an uncertainty represented by parameters of a probability density function. As an application, confidence intervals for the two parameters of the Weibull distribution along with their joint confidence interval are derived. The...
[ 22 ] - A Closed-Form Formula for the Fair Allocation of Gains in Cooperative N-Person Games
Abstract This paper provides a closed-form optimal solution to the multi-objective model of the fair allocation of gains obtained by cooperation among all players. The optimality of the proposed solution is first proved. Then, the properties of the proposed solution are investigated. At the end, a numerical example in inventory control environment is given to demonstrate the application and t...
[ 23 ] - A New Acceptance Sampling Design Using Bayesian Modeling and Backwards Induction
In acceptance sampling plans, the decisions on either accepting or rejecting a specific batch is still a challenging problem. In order to provide a desired level of protection for customers as well as manufacturers, in this paper, a new acceptance sampling design is proposed to accept or reject a batch based on Bayesian modeling to update the distribution function of the percentage of nonconfor...
[ 24 ] - A Simple Transformation Method in Skewness Reduction
Statistical analysis of non-normal data is usually more complicated than that for normaldistribution. In this paper, a simple root/power transformation technique developed by Niaki, et al [1]is extended to transform right and left skewed distributions to nearly normal. The value of theroot/power is explored such that the skewness of the transformed data becomes almost zero with anacceptable err...
[ 25 ] - A Generalized Linear Statistical Model Approach to Monitor Profiles
Statistical process control methods for monitoring processes with univariate ormultivariate measurements are used widely when the quality variables fit to known probabilitydistributions. Some processes, however, are better characterized by a profile or a function of qualityvariables. For each profile, it is assumed that a collection of data on the response variable along withthe values of the c...
[ 26 ] - Resource Investment Problem With Discounted Cash Flows
A resource investment problem is a project-scheduling problem in which the availability levels of the resources are considered decision variables and the goal is to find a schedule and resource requirement levels such that some objective function optimizes. In this paper, we consider a resource investment problem in which the goal is to maximize the net present value of the project cash flows. ...
[ 27 ] - Resource Investment Problem with Discounted Cash Flows
A resource investment problem is a project-scheduling problem in which the availability levels of the resources are considered as decision variables and the goal is to find a schedule, and resource requirement levels, such that some objective function optimizes. In this paper, we consider a resource investment problem in which the goal is to maximize the net present value of the project cash fl...
[ 28 ] - On the Performance of a Multivariate Control Chart in Multistage Environment
In this paper, a Multivariate-Multistage Quality Control (MVMSQC) procedure is investigated. In this procedure discriminate analysis, linear regression and control chart theory are combined to control the means of correlated characteristics of a process, which involves several serial stages. Furthermore, the quality of the output at each stage depends on the output of the previous stage as well...
[ 29 ] - A Multivariate Quality Control Procedure in Multistage Production Systems
In this paper a multivariate quality control procedure is offered in which several correlated stages are present in production systems and in each stage there are several correlated control variable. Using Hotelling's T2 statistic, first, each stage is tested for being out of control. Then out of control variables are selected using Murphy's method. The remainder of the research involves evalua...
[ 30 ] - Confidence Interval Estimation of the Mean of Stationary Stochastic Processes: a Comparison of Batch Means and Weighted Batch Means Approach (TECHNICAL NOTE)
Suppose that we have one run of n observations of a stochastic process by means of computer simulation and would like to construct a condifence interval for the steady-state mean of the process. Seeking for independent observations, so that the classical statistical methods could be applied, we can divide the n observations into k batches of length m (n= k.m) or alternatively, transform the cor...
[ 31 ] - A Procedure for Building Confidence Interval on the Mean of Simulation Output Data
One of the existing methods to build a confidence interval (c.i.) for the mean response in a single steady state simulation system is the batch means method. This method, compared to the other existing methods (autoregressive representation, regenerative cycles, spectrum analysis, standardized time series), is quite easy to understand and to implement and performs relatively well. However, the ...
[ 32 ] - A Scenario-Based Nonlinear Programming Model for a Two-Level Inventory Control Problem: A Case in Dairy Product Industry
In this paper, a novel scenario-based two-level inventory control model with a limited budget is formulated. The demand during the selling period is considered to follow a uniform probability distribution. In addition, it is assumed that there will be some customers who are willing to wait for their demands to be satisfied; thus a service level is considered for these customers. The aim is to f...
[ 33 ] - An Efficient Economic-Statistical Design of Simple Linear Profiles Using a Hybrid Approach of Data Envelopment Analysis, Taguchi Loss Function, and MOPSO
Statistically constrained economic design for profiles usually refers to the selection of some parameters such as the sample size, sampling interval, smoothing constant, and control limit for minimizing the total implementation cost while the designed profiles demonstrate a proper statistical performance. In this paper, the Lorenzen-Vance function is first used to model the implementation...
[ 34 ] - A Risk-averse Inventory-based Supply Chain Protection Problem with Adapted Stochastic Measures under Intentional Facility Disruptions: Decomposition and Hybrid Algorithms
Owing to rising intentional events, supply chain disruptions have been considered by setting up a game between two players, namely, a designer and an interdictor contesting on minimizing and maximizing total cost, respectively. The previous studies have found the equilibrium solution by taking transportation, penalty and restoration cost into account. To contribute further, we examine how incor...
[ 35 ] - Availability analysis of a cooking oil production line
Availability and reliability of a manufacturing system are the most common indicators in the reliability engineering area to assess the quality and on-time deliveries of the products they produce. The purpose of this paper is to analyze the availability, reliability. failure metrics such as MTBF and MTTF, and also steady-state availability of a cooking oilproduction line using a Markov approach...
[ 36 ] - Direct Aperture Optimization for Intensity Modulated Radiation Therapy: Two Calibrated Metaheuristics and Liver Cancer Case Study
Integrated treatment planning for cancer patients has high importance in intensity modulated radiation therapy (IMRT). Direct aperture optimization (DAO) is one of the prominent approaches used in recent years to attain this goal. Considering a set of beam directions, DAO is an integrated approach to optimize the intensity and leaf position of apertures in each direction. In this paper, first, ...
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