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Article
Publication date: 1 August 2016

Hamed Fazlollahtabar

This paper aims to propose a parallel automated assembly line system to produce multiple products in a semi-continuous system.

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Abstract

Purpose

This paper aims to propose a parallel automated assembly line system to produce multiple products in a semi-continuous system.

Design/methodology/approach

The control system developed in this research consists of a manufacturing system for two-level hierarchical dynamic decisions of autonomous/automated/automatic-guided vehicles (AGVs) dispatching/next station selection and machining schedules and a station control scheme for operational control of machines and components. In this proposed problem, the assignment of multiple AGVs to different assembly lines and the semi-continuous stations is a critical objective. AGVs and station scheduling decisions are made at the assembly line level. On the other hand, component and machining resource scheduling are made at the station level.

Findings

The proposed scheduler first decomposes the dynamic scheduling problems into a static AGV and machine assignment during each short-term rolling window. It optimizes weighted completion time of tasks for each short-term window by formulating the task and resource assignment problem as a minimum cost flow problem during each short-term scheduling window. A comprehensive decision making process and heuristics are developed for efficient implementation. A simulation study is worked out for validation.

Originality/value

Several assembly lines are configured to produce multiple products in which the technologies of machines are shared among the assembly lines when required. The sequence of stations is pre-specified in each assembly line and the components of a product are kept in machine magazine. The transportation between the stations in an assembly line (intra assembly line) and among stations in different assembly lines (inter assembly line) are performed using AGVs.

Details

Assembly Automation, vol. 36 no. 3
Type: Research Article
ISSN: 0144-5154

Keywords

Article
Publication date: 23 June 2015

Hamed Fazlollahtabar, Mohammad Saidi-Mehrabad and Ellips Masehian

This paper aims to propose and formulate a complicated routing/scheduling problem for multiple automated guided vehicles (AGVs) in a manufacturing system.

1045

Abstract

Purpose

This paper aims to propose and formulate a complicated routing/scheduling problem for multiple automated guided vehicles (AGVs) in a manufacturing system.

Design/methodology/approach

Considering the due date of AGVs requiring for material handling among shops in a jobshop layout, their earliness and tardiness are significant in satisfying the expected cycle time and from an economic view point. Therefore, the authors propose a mathematical program to minimize the penalized earliness and tardiness for a conflict-free and just-in-time production.

Findings

The model considers a new concept of turning point for deadlock resolution. As the mathematical program is difficult to solve with a conventional method, an optimization method in two stages, namely, searching the solution space and finding optimal solutions are proposed. The performance of the proposed mathematical model is tested in a numerical example.

Practical implications

A case study in real industrial environment is conducted. The findings lead the decision-makers to develop a user interface decision support as a simulator to plan the AGVs’ movement through the manufacturing network and help AGVs to prevent deadlock trap or conflicts. The proposed decision support can easily be commercialized.

Originality/value

The benefits of such commercialization are increase in the quality of material handling, improve the delivery time and prevent delays, decrease the cost of traditional handling, capability of computerized planning and control, intelligent tracking and validation experiments in simulation environment.

Details

Industrial Robot: An International Journal, vol. 42 no. 3
Type: Research Article
ISSN: 0143-991X

Keywords

Article
Publication date: 26 June 2021

Hamed Fazlollahtabar, Mohammad Saidi-Mehrabad and Ellips Masehian

The purpose of this study is to investigate the benefits of the turning point layout; a simulation model being applicable for strategic level is designed that compares systems…

184

Abstract

Purpose

The purpose of this study is to investigate the benefits of the turning point layout; a simulation model being applicable for strategic level is designed that compares systems with and without turning points. Specifically, the avoidance of deadlocks and prevention of conflicts is substantial.

Design/methodology/approach

Optimization process for different layouts and configuration of autonomous guided vehicles (AGVs) are worked out using statistical methods for design parameters. Regression analysis is used to find effective design parameters and analysis of variance is applied for adjusting critical factors. Also, the optimal design is then implemented in a manufacturing system for an industrial automation and the results are reported.

Findings

The outputs imply the effectiveness of the proposed approach for real industrial cases. This research will combine both simulation-based method and optimization technique to improve the quality of solutions.

Originality/value

In AGV systems, the begin-end combinations are usually connected by using a fixed layout, which is not the optimal path. The capability of these configurations is limited and often the conflict of multiple AGVs and deadlock are inevitable. By appearing more flexible layouts and advanced technology, the positioning and dispatching of AGVs increased. A new concept would be to determine each path dynamically. This would use the free paths for AGVs leading to overcome the conflicts and deadlocks.

Details

Assembly Automation, vol. 41 no. 4
Type: Research Article
ISSN: 0144-5154

Keywords

Article
Publication date: 14 August 2017

Mehdi Abedi, Hany Seidgar and Hamed Fazlollahtabar

The purpose of this paper is to present a new mathematical model for the unrelated parallel machine scheduling problem with aging effects and multi-maintenance activities.

Abstract

Purpose

The purpose of this paper is to present a new mathematical model for the unrelated parallel machine scheduling problem with aging effects and multi-maintenance activities.

Design/methodology/approach

The authors assume that each machine may be subject to several maintenance activities over the scheduling horizon and a machine turn into its initial condition after maintenance activity and the aging effects start anew. The objective is to minimize the weighted sum of early/tardy times of jobs and maintenance costs.

Findings

As this problem is proven to be non-deterministic polynomial-time hard (NP-hard), the authors employed imperialist competitive algorithm (ICA) and genetic algorithm (GA) as solution approaches, and the parameters of the proposed algorithms are calibrated by a novel parameter tuning tool called Artificial Neural Network (ANN). The computational results clarify that GA performs better than ICA in quality of solutions and computational time.

Originality/value

Predictive maintenance (PM) activities carry out the operations on machines and tools before the breakdown takes place and it helps to prevent failures before they happen.

Details

Journal of Modelling in Management, vol. 12 no. 3
Type: Research Article
ISSN: 1746-5664

Keywords

Article
Publication date: 8 May 2019

Hassan Arabshahi and Hamed Fazlollahtabar

This paper presents a stepwise method for identification and analysis of innovative activities in production systems. The purpose of this paper is to provide a structure in order…

Abstract

Purpose

This paper presents a stepwise method for identification and analysis of innovative activities in production systems. The purpose of this paper is to provide a structure in order to propose the risk paradigms and factors corresponding to the innovative activities and evaluation of the impact of these activities on innovation decisions and investment.

Design/methodology/approach

The model used here is an analytical approach that evaluates the impact of innovative activities on innovation decision and investment using product opportunity gap (POG) concept. This framework is applied for innovative activities of Asian industrial field, and the risk of innovative activities is calculated by weighted risk analysis method. In this method, the risk weights and intensities are estimated by the average of experts’ opinions in interviews.

Findings

This implementation discovered some useful information being used by investors, innovators and policymakers for taking the best strategies and decisions in various innovation domains such as innovation management, risk management and innovation policy. The results of this study show that the product innovation is the most popular category of innovation that has occurred in Asian manufacturing industries, and the product innovation, marketing innovation and organizational innovation have the most influence on technology, economic and social changes intensity, respectively.

Research limitations/implications

This study analyzed the risk of innovative activities after their occurrence and because of different views of experts, there were diverse and sometimes contradictory analyses of innovative activities risk.

Originality/value

This paper links two separate and important sectors of innovation domain: innovation risk and innovation decision making and investment. POG plays the role of a bridge to connect the two mentioned sectors and shows how innovation causes the technological, economic and social changes. This paper also provides useful and practical information for innovation investors and decision makers to take the best decisions and to avoid the probable failures and losses.

Details

The TQM Journal, vol. 31 no. 6
Type: Research Article
ISSN: 1754-2731

Keywords

Article
Publication date: 16 October 2017

Hamed Fazlollahtabar and Seyed Taghi Akhavan Niaki

This paper aims to conduct a comprehensive fault tree analysis (FTA) on the critical components of industrial robots. This analysis is integrated with the reliability block…

729

Abstract

Purpose

This paper aims to conduct a comprehensive fault tree analysis (FTA) on the critical components of industrial robots. This analysis is integrated with the reliability block diagram (RBD) approach to investigate the robot system reliability.

Design/methodology/approach

For practical implementation, a particular autonomous guided vehicle (AGV) system was first modeled. Then, FTA was adopted to model the causes of failures, enabling the probability of success to be determined. In addition, RBD was used to simplify the complex system of the AGV for reliability evaluation purpose.

Findings

Hazard decision tree (HDT) was configured to compute the hazards of each component and the whole AGV robot system. Through this research, a promising technical approach was established, allowing decision-makers to identify the critical components of AGVs along with their crucial hazard phases at the design stage.

Originality/value

As complex systems have become global and essential in today’s society, their reliable design and determination of their availability have turned into very important tasks for managers and engineers. Industrial robots are examples of these complex systems that are being increasingly used for intelligent transportation, production and distribution of materials in warehouses and automated production lines.

Details

Industrial Robot: An International Journal, vol. 44 no. 6
Type: Research Article
ISSN: 0143-991X

Keywords

Article
Publication date: 23 August 2019

Sahar Tadayonirad, Hany Seidgar, Hamed Fazlollahtabar and Rasoul Shafaei

In real manufacturing systems, schedules are often disrupted with uncertainty factors such as random machine breakdown, random process time, random job arrivals or job…

Abstract

Purpose

In real manufacturing systems, schedules are often disrupted with uncertainty factors such as random machine breakdown, random process time, random job arrivals or job cancellations. This paper aims to investigate robust scheduling for a two-stage assembly flow shop scheduling with random machine breakdowns and considers two objectives makespan and robustness simultaneously.

Design/methodology/approach

Owing to its structural and algorithmic complexity, the authors proposed imperialist competitive algorithm (ICA), genetic algorithm (GA) and hybridized with simulation techniques for handling these complexities. For better efficiency of the proposed algorithms, the authors used artificial neural network (ANN) to predict the parameters of the proposed algorithms in uncertain condition. Also Taguchi method is applied for analyzing the effect of the parameters of the problem on each other and quality of solutions.

Findings

Finally, experimental study and analysis of variance (ANOVA) is done to investigate the effect of different proposed measures on the performance of the obtained results. ANOVA's results indicate the job and weight of makespan factors have a significant impact on the robustness of the proposed meta-heuristics algorithms. Also, it is obvious that the most effective parameter on the robustness for GA and ICA is job.

Originality/value

Robustness is calculated by the expected value of the relative difference between the deterministic and actual makespan.

Article
Publication date: 14 May 2018

Sepideh Eskandari Dorabati, Ali Zeinal Hamadani and Hamed Fazlollahtabar

Due to the fact that the non-standard products, being used by customers, may cause failures in products with sales delays, which naturally affect the warranty policy. Thus, it…

Abstract

Purpose

Due to the fact that the non-standard products, being used by customers, may cause failures in products with sales delays, which naturally affect the warranty policy. Thus, it seems to be necessary to study these two concepts simultaneously. The paper aims to discuss these issues.

Design/methodology/approach

In this paper, a model is developed for estimating the expected warranty costs under sales delay conditions when two operator costs (failing but not reported and non-failing but reported) are included.

Findings

The proposed model is validated using a numerical example for a two types of intermittent and fatal failures occur under a non-renewing warranty policy.

Originality/value

Sales delay is the time interval between the date of production and the date of sale. Most reported literature on warranty claims data analysis related to sales delay have mainly focussed on estimating the probability distribution of the sales delay.

Details

Journal of Quality in Maintenance Engineering, vol. 24 no. 2
Type: Research Article
ISSN: 1355-2511

Keywords

Article
Publication date: 6 April 2021

Hamed Fazlollahtabar and Navid Kazemitash

However, due to the huge number of studies and on the other hand to be new and creative, the represented models and methods – as the two main parts of this field – have been got…

Abstract

Purpose

However, due to the huge number of studies and on the other hand to be new and creative, the represented models and methods – as the two main parts of this field – have been got more complicated, which consequently have been turned into unpractical research studies for the realistic situations. Therefore, the purpose of this study is the representation of a novel and simple method to deal with the aforementioned gap.

Design/methodology/approach

To this end, Fazl-Tash method have been proposed, in which a thorough and complete model including 114 criteria and a simple technique to rank and select the best supplier have been presented. Sustainability and resiliency are considered in collecting criteria effective on supplier selection.

Findings

The method was carried out in a case study in an industrial company. The efficiency of the proposed method is evaluated in comparison with other conventional approaches.

Originality/value

As selecting the supplier plays a crucial role to bring some important advantages for companies, such as coping with the cost and time problems and influencing the majority of contemporary markets’ requirements, in recent years, there have been representing more effective studies in the supplier selection literature.

Details

Kybernetes, vol. 51 no. 1
Type: Research Article
ISSN: 0368-492X

Keywords

Article
Publication date: 18 August 2021

Samane Babaeimorad, Parviz Fattahi and Hamed Fazlollahtabar

The purpose of this paper is to present an integrated strategy for inventory control and preventive maintenance planning for a single-machine production system with increasing…

Abstract

Purpose

The purpose of this paper is to present an integrated strategy for inventory control and preventive maintenance planning for a single-machine production system with increasing failure rates.

Design/methodology/approach

There are three scenarios for solving presented model. The strategy is such that the production component is placed under maintenance as soon as it reaches the m level or in the event of a malfunction earlier than m. Maintenance completion time is not predictable. As a result of periodic maintenance, a buffer stock h is held and the production component starts to produce from period A with the maximum throughput to satisfy demand and handle the shortage. A numerical algorithm to find the optimal policy is developed. The algorithm is implemented using MATLAB software.

Findings

The authors discovered that joint optimization mainly reduces production system costs. Cs is holding cost of a product unit during a unit of time. The authors consider two values for Cs, consist of, Cs = 1 and Cs = 2. By comparing the two cases, it is concluded that by reducing the cost from Cs = 2 to Cs = 1, the optimal scenario does not differ. The amount of decision variables decreases.

Originality/value

This paper is the provision of a model in which the shortage of back order type is considered, which greatly increases the complexity of the problem compared to similar issues. The methods for solving such problems are provided by the numerical algorithm, and the use of buffers as a way to compensate for the shortage in the event of a complete shutdown of the production line which is a very effective and efficient way to deal with customer loss.

Details

Journal of Quality in Maintenance Engineering, vol. 28 no. 4
Type: Research Article
ISSN: 1355-2511

Keywords

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