Operations Research
Seife Ebeyedengel Tekletsadik
Abstract
Productivity improvement is important for the sustainability of the business. However, before improvement it is important to measure the existing system productivity level. In this sense, the productivity of the case company has been measured by using the PO-P approach. Using this approach, the overall ...
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Productivity improvement is important for the sustainability of the business. However, before improvement it is important to measure the existing system productivity level. In this sense, the productivity of the case company has been measured by using the PO-P approach. Using this approach, the overall productivity of the case company has become 0.652. By having the ergonomic sub system and strategic goal of the case company, goal programing has been formulated to show by how much percent does the ergonomics subsystem alone will improve the overall productivity level. For this, it is required to have optimal solution of performance value of the performance objectives of the ergonomics sub-system. The optimal solution of the excel solver has given the suggested performance values of x3=1.035, x4= 0.82, x5=0.7, x6=0.8, x7=2.76, x8=0.75, x9=0.8, x10=0.5, and x11=0.4. Having these values, the productivity of the ergonomics subsystem became 1.492, in effect increased the overall productivity from 0.652 to 0.776.
Operations Research
Md. Kawsar Ahmed Asif; Shahriar Tanvir Alam; Sohana Jahan; Md. Rajib Arefin
Abstract
Sequencing and scheduling are the forms of decision-making approach that play a vital role in the automation and services industries. Efficient scheduling can help the industries to achieve the full potential of their supply chains. Conversely, inefficient scheduling causes additional idle time for machines ...
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Sequencing and scheduling are the forms of decision-making approach that play a vital role in the automation and services industries. Efficient scheduling can help the industries to achieve the full potential of their supply chains. Conversely, inefficient scheduling causes additional idle time for machines and reduces productivity, which may escalate the product price. This study aims to find the most effective algorithm for solving sequencing and scheduling problems in a non-preemptive flow shop environment where the objective functions are to reduce the total elapsed time and idle time. In this research, four prominent exact algorithms are considered and examined their efficiency by calculating the ‘total completion time’ and their goodness. In order to demonstrate the comparative analysis, numerical examples are illustrated. A Gantt chart is additionally conducted to exhibit the efficiency of these algorithms graphically. Eventually, a feasible outcome for each condition has been obtained by analyzing these four algorithms, which leads to getting a competent, time and cost-efficient algorithm.
Operations Research
Chokri Ben Salem; Walid Meslameni
Abstract
Bending is a sheet forming operation in excess of the elasticity limit of the material. Currently, in the industry, bending operation is carried out by a successive test method in order to have the geometry of the part, which generates the operation quite long and too expensive. In fact, springback brings ...
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Bending is a sheet forming operation in excess of the elasticity limit of the material. Currently, in the industry, bending operation is carried out by a successive test method in order to have the geometry of the part, which generates the operation quite long and too expensive. In fact, springback brings about geometric changes in the folded parts. This phenomenon affects the angle and radius of curvature and can be primarily influenced by multiple factors. In this work, we predict the springback during the air v-bending procedure with the finite element calculation software ABAQUS to pass the test on the first try. The simulation parameters followed the real setting taking into account the characteristics of the punch and the die of the hydraulic press. The simulation was then checked using experimental tests and analytical models, we study this particular springback in 1050A Aluminum specimens through the analytical models of Gardiner and Queener. As a final result, the springback comparison effect between simulation and experiment is presented, and the evaluation of the experimental results with those of the simulation and theoretical models is conclusive. The simulated data show good agreement with the experimental and the analytical models the Finite Element Method (FEM) is a reliable tool for the analysis and simulation of the air v-bending process of Aluminum 1050 A sheet.
Operations Research
S. K. Das; J. K. Dash
Abstract
Neutrosophic Linear Programming (NLP) issues is presently extensive applications in science and engineering. The primary commitment right now to manage the NLP problem where the coefficients are neutrosophic triangular numbers with blended requirements. The current method [20] are viewed as just imbalance ...
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Neutrosophic Linear Programming (NLP) issues is presently extensive applications in science and engineering. The primary commitment right now to manage the NLP problem where the coefficients are neutrosophic triangular numbers with blended requirements. The current method [20] are viewed as just imbalance limitations. Notwithstanding, in our paper, we consider both blended requirements and utilize another score function to understand the strategy. To determine the progression of the current method, another strategy is proposed for tackling NLP issues. To check the better outcome, we execute various numerical models.
Operations Research
M. Rabbani; A. H. Khezri; H. Farrokhi-Asl; S. Aghamohamadi-Bosjin
Abstract
In recent years, robots have been an eminent solution for manufacturers to facilitate their process and focus on a variety of their products. As the importance of robot usages, our paper focuses on the robotics assembly line. In this paper, we have considered the cycle time, robot operational costs, ...
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In recent years, robots have been an eminent solution for manufacturers to facilitate their process and focus on a variety of their products. As the importance of robot usages, our paper focuses on the robotics assembly line. In this paper, we have considered the cycle time, robot operational costs, robot purchase costs, and robot energy consumptions. In the following, we add robot failure rates to have an efficient and high-quality assembly line. The presented model is a multi-objective problem, therefore, the linear programming methods as goal programming and augmented ε-constraint method are applied to optimize the problem. In the end, we have considered a case study to examine and show the applicability of the proposed model on the real situation.
Operations Research
M. Movafaghpour
Abstract
The purpose of this study is to provide a proper method for evaluating performance of teachers, which leads to authorities awareness about the quality and quantity of activities that are acceptable to the organization; also creating the grounds for empowering human resources, reduction of dissatisfaction, ...
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The purpose of this study is to provide a proper method for evaluating performance of teachers, which leads to authorities awareness about the quality and quantity of activities that are acceptable to the organization; also creating the grounds for empowering human resources, reduction of dissatisfaction, and complaints. This can result in eliminating discrimination or unfair judgments and therefore reduction of tensions, and conflicts between managers and employees. The Analytic Hierarchy Process (AHP) which was developed by Saaty is a decision analysis tool. It has been applied to many different decision fields. In this paper, we use AHP as a performance assessment tool to inquire diverse assessments in the organization about the performance of each employee. Since the number of the items to be compared in AHP is increased, the number of pairwise comparisons that each assessor answer, are increased drastically. So, we develop a method called EVMP to elicit the preference vector of pairwise comparison matrices with missing entries. The newly developed method is tested in a school; the generated results have been proved by experts.
Operations Research
M. Rabbani; S. Aghamohamadi; H. Farrokhi-Asl; M. Alavi mofrad
Abstract
In this paper, a new multi-objective time-cost constrained resource availability cost problem is proposed. The mathematical model is aimed to minimize resource availability cost by considering net present value of resource prices in order to evaluate the economic aspects of project to maximize the quality ...
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In this paper, a new multi-objective time-cost constrained resource availability cost problem is proposed. The mathematical model is aimed to minimize resource availability cost by considering net present value of resource prices in order to evaluate the economic aspects of project to maximize the quality of project's resources to satisfy the expectations of stakeholders and to minimize the variation of resource usage during project. Since the problem is NP-hard, to deal with the problem a simulated annealing approach is applied, also to validate our results GAMS software is used in small size test problems. Due to the dependency of SA algorithm to its initial parameters a taghuchi method is used to find the best possible SA parameters combinations to reach near optimum solutions in large size problems.
Operations Research
M. A. Abdel Khalek; F. I. El-Hosiny; K. A. Selim; I. Osama
Abstract
A novel continuous electroflotation cell, about 0.6 liter volume capacity, using aluminum electrodes was designed for oil produced water treatment. The treating performance of a novel continuous electroflotation cell for oil produced water was investigated. The pH, current density, and feed water flow ...
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A novel continuous electroflotation cell, about 0.6 liter volume capacity, using aluminum electrodes was designed for oil produced water treatment. The treating performance of a novel continuous electroflotation cell for oil produced water was investigated. The pH, current density, and feed water flow rate as affecting parameters of electroflotation process were studied. The results show that the removal efficiency decreased with increasing feed flow rate. However, it increased with increasing current density. The AC current was preferred because DC current causes passivation of the anode with time. The maximum removal for all types of pollutants is achieved at pH6. The designed electroflotation cell could remove different constituents of oil produced water with range 87.5 - 99.5 % at 25°C, 5V, pH7 and AC current density of 80A/m2 through a bipolar connection of the 8 electrodes with feed water flow rate of 60ml/min (3.6l/hr). The energy consumption was about 1.38Kwh/m3 and the operating cost (cost/m3) was about 0.3US$/m3 for the produced water treatment.
Operations Research
S.K. Das; T. Mandal
Abstract
In this paper, a solution procedure is proposed to solve Fully Fuzzy Linear Fractional Programming (FFLFP) problem where all the variables and parameters are triangular fuzzy numbers. Here, FFLFP problem transformed into an equivalent Multi- Objective Linear Fractional Programming (MOLFP) problem. Then ...
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In this paper, a solution procedure is proposed to solve Fully Fuzzy Linear Fractional Programming (FFLFP) problem where all the variables and parameters are triangular fuzzy numbers. Here, FFLFP problem transformed into an equivalent Multi- Objective Linear Fractional Programming (MOLFP) problem. Then MOLFP converted into an equivalent multi objective linear programming problem by using mathematical programming approach. The proposed solution illustrated through numerical examples and compared with existing methods.
Operations Research
H. Golpira; S. E. Najafi; M. Zandieh; S. Sadi-Nezhad
Abstract
This paper formulates a competitive supply chain network throughout a mixed integer linear programming problem, considering demand uncertainty and retailers risk averseness. That is, makes the model more realistic in comparison with the others. Employed conditional value at risk method through the data-driven ...
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This paper formulates a competitive supply chain network throughout a mixed integer linear programming problem, considering demand uncertainty and retailers risk averseness. That is, makes the model more realistic in comparison with the others. Employed conditional value at risk method through the data-driven approach, makes the model to be convex and sensitive to the risk averseness level. Finally, the model outputs and its results are illustrated through a numerical example.
