Ashkan Ayough, Reza Rafiei and Ashkan Shabbak
The purpose of this paper is to develop a distribution management system that determines the path toward lean distribution through teamwork. This system introduces a set of lean…
Abstract
Purpose
The purpose of this paper is to develop a distribution management system that determines the path toward lean distribution through teamwork. This system introduces a set of lean distribution initiatives regarding the structural and strategic facets of organizations.
Design/methodology/approach
Through studying the case, which is one of the largest distribution companies in the Middle East, the deployment process of the developed system is examined through chartering focus, deployment and operational teams. These teams held several rounds of panel discussions to formulate the strategic, tactical and technical plans required for making distribution operations lean.
Findings
It is found that the strategic focus of the case should not only be restricted to distribution initiatives but also the company can achieve a suitable competitive position by focusing on leadership and integral architecture of information, distribution and transportation channels. The first semi-year cycle of implementing the lean distribution system in the case targeted a 2.5% reduction in the ratio of distribution cost to sales by planning for the cross-docking adoption. It also aimed at a 10% increase in the market share for the prioritized market by a 20% reduction in lost sales owing to improper implementation of the processes.
Originality/value
The developed lean distribution management system is novel in the way it includes the strategy, structure and capabilities of an organization. Deploying this system causes a meaningful connection between lean distribution principles and operational initiatives.
Details
Keywords
Ashkan Ayough, Farbod Farhadi and Mostafa Zandieh
This paper aims to unfold the role that job rotation plays in a lean cell. Unlike many studies, the authors consider heterogeneous operators with dynamic performance factor that…
Abstract
Purpose
This paper aims to unfold the role that job rotation plays in a lean cell. Unlike many studies, the authors consider heterogeneous operators with dynamic performance factor that is impacted by the assignment and scheduling decisions. The purpose is to derive an understanding of the underlying effects of job rotations on performance metrics in a lean cell. The authors use an optimization framework and an experimental design methodology for sensitivity analysis of the input parameters.
Design/methodology/approach
The approach is an integration of three stages. The authors propose a set-based optimization model that considers human behavior parameters. They also solve the problem with two meta-heuristic algorithms and an efficient local search algorithm. Further, the authors run a post-optimality analysis by conducting a design of experiments using the response surface methodology (RSM).
Findings
The results of the optimization model reveal that the job rotation schedules and the human cognitive metrics influence the performance of the lean cell. The results of the sensitivity analysis further show that the objective function and the job rotation frequencies are highly sensitive to the other input parameters. Based on the findings from the RSM, the authors derive general rules for the job rotations in a lean cell given the ranges in other input variables.
Originality/value
The authors integrate the job rotation scheduling model with human behavioral and cognitive parameters and formulate the problem in a lean cell for the first time in the literature. In addition, they use the RSM for the first time in this context and offer a post-optimality analysis that reveals important information about the impact of the job rotations on the performance of operators and the entire working cell.
Details
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Ashkan Ayough, Behrooz Khorshidvand, Negah Massomnedjad and Alireza Motameni
As a critical problem in sophisticated distribution systems, vehicle routing plays a pivotal role in dealing with time windows and capacities constraints. The purpose of this…
Abstract
Purpose
As a critical problem in sophisticated distribution systems, vehicle routing plays a pivotal role in dealing with time windows and capacities constraints. The purpose of this paper is to addresses a new integrated model to incorporate both three-dimensional and time windows aspects of the routing problem. First, capacitated vehicle routing decisions are made subject to a soft time interval to meet the customers’ demands. Afterward, these decisions are entered into the three-dimensional loading problem.
Design/methodology/approach
The problem is solved using generalized algebraic modeling system software in small-size problems. The problem is NP-hard and requires an efficient solution methodology. For this purpose, a hybrid algorithm has been proposed to solve the large-size problems. The efficiency of this algorithm is checked by making comparisons with exact solutions for small and medium size test problems, and with the related literature for large size problems.
Findings
The numerical experiments show that the proposed model covers more effectively the broader aspects of the transportation problem. Furthermore, the proposed algorithm supports competitive and satisfactory results by giving reasonable outputs in comparison with previous studies.
Originality/value
The main purpose of this integration is to achieve minimum total transportation costs, which cannot be guaranteed without applying two referred constraints, simultaneously.
Details
Keywords
Ashkan Ayough, Mohammad Hosseinzadeh and Alireza Motameni
Line–cell conversion and rotation of operators between cells are common in lean production systems. Thus, the purpose of this study is to provide an integrated look at these two…
Abstract
Purpose
Line–cell conversion and rotation of operators between cells are common in lean production systems. Thus, the purpose of this study is to provide an integrated look at these two practices through integrating job rotation scheduling and line-cell conversion problems, as well as investigating the effect of rotation frequency on flow time of a Seru system.
Design/methodology/approach
First, a nonlinear integer programming model of job rotation scheduling problem and line–cell conversion problem (Seru-JRSP) was presented. Then, because Seru-JRSP is NP-hard, an efficient and effective invasive weed optimization (IWO) algorithm was developed. Exploration process of IWO was enhanced by enforcing two shake mechanisms.
Findings
Computations of various sample problems showed shorter flow time and less number of assigned operators in a Seru system scheduled through job rotation. Also, nonlinear behavior of flow time versus number of rotation periods was shown. It was demonstrated that, setting number of rotation frequency to one in line with the literature leads to inferior flow time. In addition, ability of developed algorithm to generate clusters of equivalent solutions in terms of flow time was shown.
Originality/value
In this research, integration of job rotation scheduling and line–cell conversion problems was introduced, considering lack of an integrated look at these two practices in the literature. In addition, a new improved IWO equipped with shake enforcement was introduced.
Details
Keywords
Mohammad Reza Moniri, Akbar Alem Tabriz, Ashkan Ayough and Mostafa Zandieh
The purpose of this paper is to propose a new framework for assessing the risks of turnaround projects in upstream oil process plants.
Abstract
Purpose
The purpose of this paper is to propose a new framework for assessing the risks of turnaround projects in upstream oil process plants.
Design/methodology/approach
This study represents a new hybrid framework for turnaround project risk assessment. First, according to experts’ opinions, the project risks were identified using interviews and brainstorming. The most important risks selected by experts and a hybrid multiple-attribute decision-making (MADM) method used to assess and prioritize them. The proposed MADM method uses fuzzy step-wise weight assessment ratio analysis (SWARA) and fuzzy evaluation based on distance from average solution (EDAS) methods based on trapezoidal fuzzy numbers.
Findings
In this research, 28 usual risks of turnaround projects are identified and 10 risks are then selected as the most important ones. The findings show, that among the risks of upstream oil industry turnaround projects from the perspective of experts, the risk of timely financing by the employer, with an appraisal score of 0.83, has the highest rank among the risks and the risk of machine and equipment failure during operation, with an appraisal score of 0.04, has the lowest rank.
Research limitations/implications
The risk analysis based on inputs collected from the experts in the Iranian upstream oil industry, and so the generalization of the results is limited to the context of developing countries, especially oil producer ones. However, the proposed risk analysis methodology and key insights developed can be useful for researchers and practitioners in any other process industry everywhere.
Originality/value
A novel framework for risk assessment is introduced for turnaround projects in the oil industry using MADM methods. There is no literature on using MADM methods for turnaround project risk analysis in the oil and gas industries. Furthermore, this paper presents a hybrid fuzzy method based on SWARA and EDAS.
Details
Keywords
Akbar Alem Tabriz, Behrooz Khorshidvand and Ashkan Ayough
The purpose of this paper is to present age-based replacement models subject to shocks and failure rate in order to determine the optimal replacement cycle. As a result, according…
Abstract
Purpose
The purpose of this paper is to present age-based replacement models subject to shocks and failure rate in order to determine the optimal replacement cycle. As a result, according to system reliability, maintenance costs of the system are to be minimized.
Design/methodology/approach
First, the modeling with respect to assumptions and two major factors (shocks and failure rate) is done. Second, by using of MATLAB the optimal parameters are obtained. Finally, analysis of results and comparison of models are done.
Findings
Analysis of results shows all models provide optimal replacement cycle and at this time, cost rate of the system by considering the reliability rate is minimal. Also with an increase of one unit to two units, reliability rate increases much higher than the rate of cost.
Originality/value
This work provides models that in addition to considering the failure rate (internal factors), also shocks as an external factor have been considered. By considering these two factors more comprehensive and adaptable models have been proposed.