Seyed Mojib Zahraee

System dynamics model for optimizing the recycling and collection of waste material in a closed-loop supply chain

Abstract To meet the immediate environmental challenges and sustainable development, Closed-loop Supply Chain (CLSC) management has become increasingly important and urgent. This is in lieu with some severe problems such as global ecological damage, resource wastages and shortages and pollution of the environment, and discretionary exploitation of natural resources. On the other hand, re-manufacturing of used merchandise and bringing them back to the market provides environmental and customer benefits to Original Equipment Manufacturers (OEMs), in addition to cutting back their production cost. This paper aims at evaluating the system behavior of an electrical manufacturing company as a case of study, by using System Dynamics (SD) simulating of Closed-loop Supply Chain (CLSC). VENSIM PLE software developed the simulation model. Based on the initial result, customer satisfaction and Green Image Factor (GIF) are lacking in the system. Therefore, to tackle this issue, an improvement model with a collection center was proposed. Results derived from the improved model presented a data of which the demand backlog level fell by 21.19%. Furthermore, the customer satisfaction in the system rose by 21.6%. In addition, as a result of an increase in GIF level from 14.80% to 48.1%, the return products rate rose from 184 items to 614. The method in this research can be used to investigate a variety of CLSC systems and their effects before implementing them in real life.

Simulation of Manufacturing Production Line Based on Arena

One of the controversial issues in manufacturing systems is bottleneck. Managers and engineers are trying to find methods to eliminate the bottlenecks and waiting times in the production line. More over the manufacturing companies are striving to sustain their competiveness by decreasing the bottlenecks, total cost and increasing the productivity. The objective of this study is applying the computer simulation to analysis the production line bottlenecks. To achieve this goal a color manufacturing line was selected as a case study and the basic application of arena 13.9 software. Finally the some modifications in the simulation model are proposed to improve the production line as well as to decrease the bottleneck.

A survey on lean manufacturing implementation in a selected manufacturing industry in Iran

Purpose Lean manufacturing (LM) practices and tools are among the key concepts that assist managers and engineers sustain competitiveness in an expanding global market. The purpose of this paper is to identify effective practices and tools of lean manufacturing implementation in an Iranian manufacturing industry. Design/methodology/approach This study used a quantitative method. Stratified random sampling and self-administrated questionnaires were sent to respondents in an Iranian manufacturing industry. Findings The final results indicate that processes and equipment, planning and control, supplier relationship, human resources and customer relations are significant practices in lean manufacturing in Iranian manufacturing factories. The results from this survey additionally show that lean tools such as Kaizen, 5S, setup time reduction, cellular manufacturing, continuous flow, equipment layout, product design simplicity and error proof equipment are crucial to lean manufacturing implementation. Research limitations/implications This study focused solely on a manufacturing industry in Iran that deals with electrical, electronic, metal, plastic, rubber and other automotive components. Practical implications The findings of this study emphasize some implications and suggest that reducing cost is more effective and decreased inventory is less effective on lean manufacturing implementation. The current study results should assist quality mangers, product managers and director managers as well as academicians. Originality/value An investigation was carried out in this study based on the current situation of Iran’s manufacturing industry to empirically examine and evaluate the effect of lean practices and tools. Besides, a very limited number of studies have been done regarding the implementation of lean thinking and practices in Iran’s manufacturing industry.

Optimization Waiting Time at Berthing Area of Port Container Terminal with Hybrid Genetic Algorithm (GA) and Artificial Neural Network (ANN)

A queuing network model related to arrival, departure and berthing process of ships at port container terminal is presented in this paper. The important datas collected from PTP port container terminal located at Malaysia. Based on the case study the model was built with using Arena 13.5 simulation software. Especially this study proposes a hybrid approach consisting of Genetic algorithm (GA), Artificial Neural Network (ANN) to find the the optimum number of equipments at berthing area of port container terminal. The input data that used in ANN obtained from Arena results. The main goal of this study is reduced waiting time of each ship at port container terminal, and Based on the result the optimum waiting time 50 will be achieved.

Evaluating the effect of main factors in manufacturing production line based on simulation experiment

Productivity plays a significant role for most companies in order to measure the efficiency. In reality there is an essential need to evaluate the different factors which increasing productivity and achieving the high level of quality, high production rate , machine utilization. On the other hand, manufacturing companies are striving to sustain their competitiveness by improving productivity and quality of manufacturing industry. So it can be acquired by finding ways to deal with various industrial problems which have affected the productivity of manufacturing systems. This paper aims at applying statistical analysis and computer simulation to recognize and to weight the significance of different factors in the production line. Based on the final result the two factors which are B (Number of labor) and C (Failure time of lifter) have the most significant effect on the manufacturing system productivity. In order to achieve the maximum productivity the factors should be placed on the levels which are: A= -1, B=1, C=1 and D=1. This means that the service rate of mixer = UNIF (20, 40), number of labor=20, failure time of lifter =60 min and number of permil=5 respectively.

Comparison of Different Scenarios Using Computer Simulation to Improve the Manufacturing System Productivity: Case Study

In the manufacturing industry, managers and engineers are seeking to find methods in order to eliminate the common problems in manufacturing systems such as bottlenecks and waiting times. This is because that all of these kinds of problems impose extra cost to the companies. In addition, manufacturing companies are striving to sustain their competitiveness by improving productivity, efficiency and quality of manufacturing industry for instance high throughput and high resource utilization. The paper concentrates on the application of computer simulation to analysis manufacturing system in order to improve the productivity. Therefore, this study introduces a color manufacturing line as a case study and the basic application of arena 13.9 software. The goal of this paper is to improve the productivity and efficiency of the production line by using computer simulation. To achieve this goal, first the basic model of the current situation of production line was simulated. Second, three different alternatives were simulated and modified to find the best scenario based on the maximum productivity and minimum total cost.

Application of Statistical Taguchi Method to Optimize Main Elements in the Residential Buildings in Malaysia Based Energy Consumption

Today energy consumption is one of the controversial issues in the world. The rapid growing world energy consumption has already increased concern about the supply problems, heavy environmental effects such as global warming, climate change and etc. One of the most users of energy is residential buildings that consume the biggest share of energy. Growth in population, rising demand for buildings together causes to increase the upward trend in energy consumption. Therefore, energy efficiency in buildings plays a significant role to decrease the environmental effect. The goal of this paper is optimizing the main elements which are window, ceiling and wall by considering the effect of uncontrollable factors such as humidity , temperature and pressure in residential buildings using statistical method namely Taguchi method (JMP 11 software). A two-storey house in Malaysia was selected to simulate by means of BIM application. Based on the result, the optimum energy saving will be achieved when the type of material which are used for wall ,ceiling and window to be Brick Plaster , Acoustic Tile Suspended and Single Glazed Alum Frame respectively.

Improving Productivity in a Bank System by Using Computer Simulation

With advent of high technologies, simulation software becomes more applicable between organizations’ managers. Simulation can model the real situation on a visual program. It will make the understanding of system, properly. Nowadays in each organization, the main considered factor is how they can improve its services confidently. This study emphasize on customer satisfaction and reducing the waiting time for customers in a bank service system. The goal of this paper is applying ARENA simulation software for modeling the system and measuring the performances. In addition, three strategies are implemented that each strategy consists of several scenarios. 17 possible scenarios are compared to achieve all kind of results that can be imagined. It would be very helpful for manager to analyzes and compare the results then find the lowest and highest effective element for improvement.

Optimization of the esterification process of crude jatropha oil (CJO) containing high levels of free fatty acids: a Malaysian case study

ABSTRACT Biodiesel as an alternative fuel is one of the best choices among other sources due to its immense potential to reduce pollutant emissions when used in compression ignition engines. Malaysia is considered one of the top biodiesel-producing countries. The main crop for biodiesel production is currently palm oil. However, Jatropha curcas has recently drawn the attention of the Malaysian government as an alternate species for producing high yields of oil. While an evaluation of biodiesel production, blending, engine performance and emissions characteristics of Malaysian-produced jatropha methyl ester has been made recently, few studies have optimized the esterification of the crude oil. This paper is the study of an optimization process for Malaysian CJO using an acid-catalyst pretreatment process to reduce the relatively high free fatty acid (FFA) percentages of crude jatropha oil to below 1% using design of experiments and response surface methodology, with the help of Minitab software. The main findings of the current investigation are that using the acid catalyst H2SO4 at 0.225% (v/v), an MeOH-to-oil ratio of 12.29% (w/w) and a reaction time of 149.76 min are the optimum process parameters for the esterification reaction.