Journal of Optimization in Industrial EngineeringJournal of Optimization in Industrial Engineering
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Feed provided by Journal of Optimization in Industrial Engineering. Click to visit.A New Version of Earned Value Analysis for Mega Projects Under Interval-valued Fuzzy Environment
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The earned value technique is a crucial and important technique in analysis and control the performance and progress of mega projects by integrating three elements of them, i.e., time, cost and scope. This paper proposes a new version of earned value analysis (EVA) to handle uncertainty in mega projects under interval-valued fuzzy (IVF)-environment. Considering that uncertainty is very common in mega projectsâ€™ activities, the proposed IVF-EVA model is very useful and applicable in evaluating the progress of projects. In this paper, analyzing earned value indices and calculating them with linguistic terms have been discussed. They are then converted into interval-valued fuzzy numbers (IVFNs) for the evaluations. Finally, an application example from the recent literature is presented and steps of the proposed IVF-EVA are elaborated.The earned value technique is a crucial and important technique in analysis and control the performance and progress of mega projects by integrating three elements of them, i.e., time, cost and scope. This paper proposes a new version of earned value analysis (EVA) to handle uncertainty in mega projects under interval-valued fuzzy (IVF)-environment. Considering that uncertainty is very common in mega projectsâ€™ activities, the proposed IVF-EVA model is very useful and applicable in evaluating the progress of projects. In this paper, analyzing earned value indices and calculating them with linguistic terms have been discussed. They are then converted into interval-valued fuzzy numbers (IVFNs) for the evaluations. Finally, an application example from the recent literature is presented and steps of the proposed IVF-EVA are elaborated.Sun, 25 Dec 2016 20:30:00 +0100Multi-Objective Optimization for Multi-Product Multi-Period Four Echelon Supply Chain Problems ...
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The multi-objective optimization for a multi-product multi-period four-echelon supply chain network consisting of manufacturing plants, distribution centers (DCs) and retailers each with uncertain services and uncertain customer nodes are aimed in this paper. The two objectives are minimization of the total supply chain cost and maximization of the average number of products dispatched to customers. The decision variables are the number and the locations of reliable DCs and retailers, the optimum number of items produced by plants, the optimum quantity of transported products, the optimum inventory of products at DCs, retailers and plants, and the optimum shortage quantity of the customer nodes. The problem is first formulated into the framework of a constrained multi-objective mixed integer linear programming model. After that, the problem is solved by using meta-heuristic algorithms that are Multi-objective Genetic Algorithm (MOGA), Fast Non-dominated Sorting Genetic Algorithms (NSGA-II) and Epsilon Constraint Methods via the MATLAB software to select the best in terms of the total supply chain cost and the total expected number of products dispatched to customers simultaneously. At the end, the performance of the proposed multi-objective optimization model of multi-product multi-period four-echelon supply chain network design is validated through three realizations and an innumerable of various analyses in a real world case study of Bangladesh. The obtained outcomes and their analyses recognize the efficiency and applicability of the proposed model under uncertainty.Sat, 29 Feb 2020 20:30:00 +0100Parallel Jobs Scheduling with a Specific Due Date: Asemi-definite Relaxation-based Algorithm
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This paper considers a different version of the parallel machines scheduling problem in which the parallel jobs simultaneously requirea pre-specifiedjob-dependent number of machines when being processed.This relaxation departs from one of the classic scheduling assumptions. While the analytical conditions can be easily statedfor some simple models, a graph model approach is required when conflicts of processor usage are present. The main decisions and solving steps are as follows, respectively. (i) Converting the scheduling problem to graph model; (ii) Dividing jobs into independent sets: in this phase, we propose a semi-definite relaxation algorithm in which we use graph coloring concept; (iii) Sequencing the independent sets as a single-machine scheduling in which jobs in such a system arejob sets formed by using a semi-definite relaxation solution and determining the problem as a schedule that minimizes the sum of the tardiness of jobs. In this regard, after grouping the jobs by a semi-definite programming relaxation algorithm, we used the rounding algorithm for graph coloring. We also proposed a variable neighborhood search algorithm for sequencing the obtained job sets in order to minimize the sum of the tardiness. Experimental results show that this methodology is interesting by obtaining good results.Wed, 31 Jan 2018 20:30:00 +0100Production Constraints Modelling: A Tactical Review Approach
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A constraint is a limitation or a restriction that poses a threat to the performance and efficiency of a system. This paper presented a tactical review approach to production constraints modeling. It discussed the theory of constraints (TOC) as a thinking process and continuous improvement strategy to curtail constraints in other to constantly increase the performance and efficiency of a system. It also x-rayed the working process of implementing the TOC concept which consists of five steps called “Process of On-Going Improvement”. Furthermore, it talked about constraints programming and constraints-based models which were explained to some details. Finally, production constraints model formulation procedures for linear programming and non-linear programming scenarios were extensively discussed with reference to published literature as instances of production constraints modeling were also cited.Sat, 29 Feb 2020 20:30:00 +0100Bi-objective Optimization of a Multi-product multi-period Fuzzy Possibilistic Capacitated Hub ...
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The hub location problem is employed for many real applications, including delivery, airline and telecommunication systems and so on. This work investigates on hierarchical hub network in which a three-level network is developed. The central hubs are considered at the first level, at the second level, hubs are assumed which are allocated to central hubs and the remaining nodes are at the third level. In this research, a novel multi-product multi-objective model for capacitated hierarchical hub location problem with maximal covering under fuzzy condition first is suggested. Cost, time, hub and central hub capacities are considered as fuzzy parameters, whereas manyparameters are uncertainty and indeterministic in the real world. To solve the proposed fuzzy possibilistic multi-objective model, first, the model is converted to the equivalent auxiliary crisp model by hybrid method and then is solved by two meta-heuristic algorithms such as Non-Dominated Sorting Genetic Algorithm (NSGA-II) and Non-Dominated Ranked Genetic Algorithm (NRGA) using MATLAB software The statistical results report that there is no significant difference between means of two algorithms exception CPU time criteria. In general, in order to show efficiency of two algorithms, we used Technique for Order of Preference by Similarity to Ideal Solution (TOPSIS), the resultsclearly show that the efficiency of NRGA is better than NSGA-II and finally, figures are achieved by MATLAB software that analyze the conflicting between two objectives.Sat, 20 Oct 2018 20:30:00 +0100Design of Supply Chain Network Model for Perishable Products with Stochastic Demand: An ...
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Supply chain network design in perishable product has become a challenging task due to its short life time, spoilage of product in degradation nature and stochastic market demand. This paper focused on designing and optimizing model for perishable product in stochastic demand, which comprises multiple levels from producer, local collector, wholesaler and retailers. The ultimate goal is to optimize availability and net profit of all members in supply chain network model for avocado fruit under stochastic demand. The network model has considered the quality deterioration rate of the product with increased order of transportation time. The validity of developed model was tested with data collected from avocado supply chain network in Ethiopian market.Sat, 29 Feb 2020 20:30:00 +0100Optimization of Multi-period Three-echelon Citrus Supply Chain Problem
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In this paper, a new multi-objective integer non-linear programming model is developed for designing citrus three-echelon supply chain network. Short harvest period, product specifications, high perished rate, and special storing and distributing conditions make the modeling of citrus supply chain more complicated than other ones. The proposed model aims to minimize network costs including waste cost, transportation cost, and inventory holding cost, and to maximize network’s profits. To solve the model, firstly the model is converted to a linear programming model. Then three multi-objective meta-heuristic algorithms are used including MOPSO, MOICA, and NSGA-II for finding efficient solutions. The strengths and weaknesses of MOPSO, MOICA, and NSGA-II for solving the proposed model are discussed. The results of the algorithms have been compared by several criteria consisting of number of Pareto solution, maximum spread, mean ideal distance, and diversification metric.Computational results show that MOPSO algorithm finds competitive solutions in compare with NSGA-II and MOICA.Sat, 29 Feb 2020 20:30:00 +0100The Regional Performance Impacts in the Supply Chain integration: Evidence from East Africa ...
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The objective of this study was to investigate the relationship between regional firm performance and supply chain integration practices. In addition to literature survey, the primary data collection instrument used was a questionnaire which was administrated to a total sample of 200 industry experts, administrative officers, functional department heads and directors, the industry managing directors and senior staff from 21 manufacturing firms in Ethiopian were incorporated. The data were studied using the AHP, fuzzy TOPSIS, the mind map, and descriptive analysis. Further, the challenges, practices, performance, the practices of East African basic metal industry supply chain integration influences the dynamics contribution of the regional economy was fragmental. According to this study, due to weak, fragmental and non-integrated supply chain systems, the regional economic dynamic contribution of the sector is weak and poor in quality, productivity, flexibility, and global competitiveness were investigated. Moreover, these investigations and analysis of this paper have both practical and scholarly implications. The result is provided to contribute to the future supply chain integration model development and make an action to supply chain integrations for process improvements. Finally, the implications for the design on the dynamic capability of supply chain strategies are showing, and the future research agenda was presentedMon, 21 Jan 2019 20:30:00 +0100Presenting a Joint Replenishment-location Model Under all-units Quantity Discount and Solving ...
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In this paper a model is proposed for distribution centers location and joint replenishment of a distribution system that is responsible for orders and product delivery to distribution centers. This distribution centers are under limitedwarehouse space and this can determine amount of requirement product by considering proposed discount.The proposed model is develop to minimize total costs consists of location, ordering, purchaseunder All-units quantity discount condition and items maintenance by adjustment Frequency of replenishment in each distribution center. To solve this model, first we solve the model with genetic algorithm by confining the time between too replenishments then by use of the Quantity Discount RAND algorithm method the upper and lower limits of the time between two replenishments will be determined. After obtaining the optimal upper and lower limits, the model will be resolved by harmony search and genetic algorithms. The results show that the presented chromosome structure is so efficient so that the statistical experiments result indicates there isn’t much difference between solution means after finding the optimal upper and lower limits. We used response surface methodology for tune proposed algorithms parameters. Efficiency of proposed algorithms is examined by diverse examples in different dimensions. Results of these experiments are compared by using of ANOVA and TOPSIS with indexes of objective function value and algorithms runtime. In both comparisons harmony search algorithm has more efficiency than genetic algorithm.Sat, 29 Feb 2020 20:30:00 +0100An Optimization Model for Heterogeneous Vehicle Routing and Scheduling Problem with Fixed Cost ...
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Vehicle routing problem aims to find the optimal routes that must be traveled by a fleet of vehicles to satisfy the demand of the customers. In this research, the vehicle routing and scheduling problem is developed for a heterogeneous fleet with the fixed cost of applying vehicles and earliness and tardiness costs in a green reverse logistics network. Since the complexity order of these problems is higher than that of the polynomial ones, this problem is known as NP-hard. As the problem dimensions increase, the exact solving time of the problem increases considerably. Thus, metaheuristic methods are proposed to approximately solve these problems. After developing mixed integer nonlinear model, the Genetic Algorithm (GA) is used to find the near-optimal solutions for the large-scale cases. Finally, the performance of the GA is investigated for several examples by comparing its computation time and solution quality with the computation time and exact solution of the LINGO software. According to the results, the developed GA has an acceptable performance in providing solutions with minimum error in a rational time.Mon, 21 Jan 2019 20:30:00 +0100A Mathematical Model for Multiple-Load AGVs in Tandem Layout
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Reducing cost of material handling has been a big challenge for companies. Flexible manufacturing system employed automated guided vehicles (AGV) to maintain efficiency and flexibility. This paper presents a new non-linear mathematical programming model to group n machines into N loops, to make an efficient configuration for AGV system in Tandem layout. The model minimizes both inter-loop, intra-loop flow and use balanced-loops strategy to balance workload in system simultaneously. This paper significantly considers multiple-load AGVs, which has capability of reducing fleet size and waiting time of works. A modified variable neighborhood search method is applied for large size problems, which has good accuracy for small and medium size problems. The results indicate that using multiple load AGV instead of single load AGV will reduce system penalty cost up to 44%.Sat, 29 Feb 2020 20:30:00 +0100ELECTRE I-based group decision methodology with risk preferences in an imprecise setting for ...
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A new hesitant fuzzy set (HFS)-ELECTRE for multi-criteria group decision-making (MCGDM) problems is developed in this paper. In real-world applications, the decision makers (DMs)’ opinions are often hesitant for decision problems; thus, considering the exact data is difficult. To address the issue, the DMs’ judgments can be expressed as linguistic variables that are converted into the HFSs, considered as inputs in the ELECTRE method. Meanwhile, an appropriate tool among the fuzzy sets theory and their extensions is the HFSs since the DMs can assign their judgments for an alternative under the evaluation criteria by some membership degrees under a set to decrease the errors. Introduced hesitant fuzzy ELECTRE (HF-ELECTRE) method is elaborated based on the risk preference of each DM with assigning some degrees. Moreover, the weight of each DM is computed and implemented in the proposed procedure to reduce judgments’ errors. Then, a new discordance HF index is provided. Pair-wise comparisons are used for outranking relations regarding HF information. Finally, the validation and verification of the proposed HF-ELECTRE method are demonstrated in a practical example of FMSs.Sat, 21 Sep 2019 20:30:00 +0100A New Bi-objective Mathematical Model to Optimize Reliability and Cost of Aggregate Production ...
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In this research, a bi-objective model is developed to deal with a supply chain including multiple suppliers, multiple manufacturers, and multiple customers, addressing a multi-site, multi-period, multi-product aggregate production planning (APP) problem. This bi-objective model aims to minimize the total cost of supply chain including inventory costs, manufacturing costs, work force costs, hiring, and firing costs, and maximize the minimum of suppliers' and producers' reliability by the considering probabilistic lead times, to improve the performance of the system and achieve a more reliable production plan. To solve the model in small sizes, a ε-constraint method is used. A numerical example utilizing the real data from a paper and wood industry is designed and the model performance is assessed. With regard to the fact that the proposed bi-objective model is NP-Hard, for large-scale problems one multi-objective harmony search algorithm is used and its results are compared with the NSGA-II algorithm. The results demonstrate the capability and efficiency of the proposed algorithm in finding Pareto solutions.Sat, 29 Feb 2020 20:30:00 +0100Enhancing Basic Metal Industry Global Competitiveness Through Total Quality Management, Supply ...
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The selection and implantation of sufficient and appropriate continuous improvement strategy are the key success factors for improving firm performance and enhancement of competitive advantage on manufacturing industries. As a result special role are given to Continuous improvement programs such as Supply Chain Management (SCM), Six-Sigma, Total Quality Management (TQM), Kaizen, Just-in-Time (JIT) and Total Productive Maintenance (TPM) in a production system, which attain sustainable business environment and competitive advantage. Thus, the aim of the study is to study the challenges and trends of global competitiveness of basic metal industries, investigates the way of integrating continuous improvement tools and then developed an integrated continuous improvement model from TQM, JIT, and SCM to improve the global competitiveness of steel and metal industries. From numerous contentious improvement programs, we have to emphasize integrated SCM, JIT and TQM implementation on basic metal industries to improve competitive performance. Mainly the study was conducted through field observation, questioner, company reports used as primary data and literature review of research articles, books, manuals, magazines, and electronic-sources, which used as secondary data. The survey data is analyzed using descriptive analysis, SPCT (fishbone diagram).The result found that poor supply chain system, workforce, raw material uncertainty, energy fluctuation, outdated technology, manufacturing systems, financial and logistics problems were identified as the obstacles and influence the Ethiopian basic metal industry performance and global competitiveness. Thus, to tackle the problems an integrated continuous improving model was developed to improve the performance and global competitiveness of basic metal industries.Sat, 21 Sep 2019 20:30:00 +0100An Efficient Economic-Statistical Design of Simple Linear Profiles Using a Hybrid Approach of ...
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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 costs. Then, this function is extended by the Taguchi loss function to involve intangible costs. Next, a multi-objective particle swarm optimization (MOPSO) method is employed to optimize the extended model. The parameters of the MOPSO are tuned using response surface methodology (RSM). In addition, data envelopment analysis (DEA) is employed to find efficient solutions among all near-optimum solutions found by MOPSO. Finally, a sensitivity analysis based on the principal parameters of the cost function is applied to evaluate the impacts of changes on the main parameters. The results show that the proposed model is robust on some parameters such as the cost of detecting and repairing an assignable cause, variable cost of sampling, and fixed cost of sampling.Sat, 29 Feb 2020 20:30:00 +0100Nurse scheduling problem by considering fuzzy modeling approach to treat uncertainty on ...
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Nowadays, the nurse scheduling problem (NSP) has attracted a great amount of attentions. In this problem,the nurses are scheduled to be assigned to the shifts by considering the required nurses for each day during the planning horizon. In the current study, a bi-objective mathematical model is formulated in order to maximize the preferences of the nurses to work on the shifts in addition to be off on the weekends. In real-world problems, higher quality schedules are provided considering the uncertainty. In this point of view, we investigate the uncertainty on the preferences of the nurses for the working shifts and the weekends off. In fact, a compensatory fuzzy approach based on the Werners’ fuzzy and operator is proposed to investigate the effects of the uncertainty on the considered research problem. Then, several sample problems are generated to support the efficiency of the developed fuzzy model. Finally, a sensitivity analysis is implemented to determine the effects of the changes of the parameters on the obtained results.Sat, 21 Sep 2019 20:30:00 +0100A system Dynamics Approach to Designing a Crowdfunding Model in Technological Entrepreneurship ...
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Crowdfunding, a new financing method for funding ideas or ventures through a large number of relatively small contributions from many individuals has witnessed the phenomenal development over the past decade. It involves bypassing traditional financial intermediaries and using online web-based platforms to connect users of funds with retail funders. This research first explores in greater detail the crowdfunding phenomenon, discussing its main aspects, as well as the role of the involved Stakeholders, and then introduce the A system dynamics approach to designing a crowdfunding model in technological entrepreneurship ecosystem with a focus on technology incubator centers. The present study is based on the system dynamics method and this research, in terms of the purpose is applied and in terms of the survey method. So for analysis of data, Vensim software has been used. The simulation results show that technological entrepreneurship ecosystem policy combinations can effectively promote crowdfunding, which attracts more entrepreneurs to provide their ideas. So crowdfunding could promote entrepreneurial to give a greater impact on economics, and contribute to building a more sustainable society.Sat, 29 Feb 2020 20:30:00 +0100Analytical Modeling of Specific Energy Consumption and Cost Share in Comprehensive Textile ...
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Energy is one of the primary inputs in textile processing industries that have a significant impact on the cost of a cotton product. The energy cost-share is reported between 5-10% of the total production cost of woven cotton fabric in textile factories of developed countries. However, it is far higher in developing countries. This study aims to contribute to the understanding of energy use and energy efficiency in Ethiopian cotton textile industries through multi-level comparisons and analyses. Determination of specific energy consumption, specific cost-share and specific energy consumption and cost estimation model is developed in cotton textile processing industries of Ethiopia to show the level of energy utilization practice effectiveness and to point out specific energy conservation measure. Actual and designed energy consumption data has been gathered from machine nameplate and factory design documents. Then important performance indicating data is collected through on-site measurement. This research pointed out that, the actual energy consumption per unit textile product is higher than the estimated consumption of each involved textile processing stage. The cost-share of energy in Ethiopian cotton textile industries accounts for an average of 16.01% of the total production cost of a cotton product and it is the second-highest cost of a product next to cotton. This indicates the existing of poor energy management practices in the textile industries. As a result, they face high production costs, poor product quality, and non-conducive working environment. This study shows that any productivity improvement measure in the textile industries of Ethiopia has to give more emphasis on the reduction of energy cost than any other production inputs.Sat, 21 Sep 2019 20:30:00 +0100Operation Sequencing Optimization in CAPP Using Hybrid Teaching-Learning Based Optimization (HTLBO)
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Computer-aided process planning (CAPP) is an essential component in linking computer-aided design (CAD) and computer-aided manufacturing (CAM). Operation sequencing in CAPP is an essential activity. Each sequence of production operations which is produced in a process plan cannot be the best possible sequence every time in a changing production environment. As the complexity of the product increases, the number of feasible sequences increase exponentially, consequently the best sequence is to be chosen. This paper aims at presenting the application of a newly developed meta-heuristic called the hybrid teaching–learning-based optimization (HTLBO) as a global search technique for the quick identification of the optimal sequence of operations with consideration of various feasibility constraints. To do so, three case studies have been conducted to evaluate the performance of the proposed algorithm and a comparison between the proposed algorithm and the previous searches from the literature has been made. The results show that HTLBO performs well in operation sequencing problem.Sat, 29 Feb 2020 20:30:00 +0100Behaviour of Individuals towards E-Waste Management in India
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Technology is changing very quickly at very cheap prices. Along with this, it becomes easier to buy any electronic product right now as compared to previous years. There are many channels (Online & Offline) available in the market to buy your desired products. Nowadays it becomes a trend: to buy new electronic products to use the latest available technology. People prefer to buy new product instead of upgrading the old product. Mobiles and laptops are the most common products which are bought frequently instead of to upgrade. Expanding usage of the mobiles, computers/laptops, and LCD/LED in all the sectors inflicting dramatically increase in generation of e-waste. E-waste referred to all kind of electric and electronic appliances that is thrown by their end user. The electronics equipments are very complex assembly structure. It contains toxic gases, toxic metals plastics, circuits, some precious metals like gold in very small quantity. The toxic substances have very adverse effect on the health of human being. These are also very dangerous for our environment also. . The objective of the study is to find how the individual consumers behave towards the e-waste. Awareness level of the individual consumers also checked. Northern Indian states are selected to conduct a study to check the awareness level of individual consumers. In this paper consumer recycling behavior was analyzed with the help of questionnaire. Figure 1 Graphical Abstract The figure shows that in all the factors, the value of mean lies between 1 and 2. It shows that most of the consumers either have no idea of hazardous materials in e-waste, concept of e-waste management and electronic waste management policies implemented in India or they have very little knowledge.Sat, 22 Feb 2020 20:30:00 +0100Monitoring of Social Network and Change Detection by Applying Statistical Process: ERGM
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The statistical modeling of social network data needs much effort because of the complex dependence structure of the tie variables. In order to formulate such dependences, the statistical exponential families of distributions can provide a flexible structure. In this regard, the statistical characteristics of the network is provided to be encapsulated within an Exponential Random Graph Model (ERGM). Applying the ERGM, in this paper, we follow to design a statistical process control through network behavior. The results demonstrated the superiority of the designed chart over the existing change detection methods in controlling the states. Additionally, the detection process is formulated for the social networks and the results are statistically analyzed.Sat, 29 Feb 2020 20:30:00 +0100A Data Mining approach for forecasting failure root causes: A case study in an Automated Teller ...
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Based on the findings of Massachusetts Institute of Technology, organizations’ data double every five years. However, the rate of using data is 0.3. Nowadays, data mining tools have greatly facilitated the process of knowledge extraction from a welter of data. This paper presents a hybrid model using data gathered from an ATM manufacturing company. The steps of the research are based on CRISP-DM. Therefore, based on the first step, business understanding, the company and its different units were studied. After business understanding, the data collected from sale's unit were prepared for preprocess. While preprocessing, data from some columns of dataset, based on their types and purpose of the research, were either categorized or coded. Then, the data have been inserted into Clementine software, which resulted in modeling and pattern discovery. The results clearly state that, the same Machines’ Code and the same customers in different provinces are struggling with significantly different Problems’ Code, that could be due to weather condition, culture of using ATMs, and likewise. Moreover, the same Machines’ Code and the same Problems’ Code, as well as differences in Technicians' expertise, seems to be some causes to significantly different Repair Time. This could be due to Technicians' training background level of their expertise and such. At last, the company can benefit from the outputs of this model in terms of its strategic decision-making.Sat, 22 Feb 2020 20:30:00 +0100Developing a New Decision Support System to Manage Human Reliability based on HEART Method
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Human performance and reliability monitoring have become the main issue for many industries since human error ratios cannot be mitigated to the zero level and many accidents, malfunctions, and quality defects are happening due to the human in production systems. Since the human resources implement a different range of tasks, the calculation of human error probability (HEP) is complicated, and several methods have been proposed to identify and quantify the HEP. This fact expresses the necessity of a Decision Support System (DSS) to calculate the HEP and propose optimal scenarios to increase human reliability and decrease its related cost such as quality defect and rework cost. This study develops a DSS that calculates the HEP based work specifications and proposes optimal scenarios to deal with error occurrence probability. The scenarios are provided using an AHP according to experts' opinions about the cost and time of corrective actions. The proposed DSS has been applied to a real case, and the provided results show that the proposed DSS can provide effective scenarios to deal with human error in production systems.Sat, 29 Feb 2020 20:30:00 +0100A Risk-averse Inventory-based Supply Chain Protection Problem with Adapted Stochastic Measures ...
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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 incorporation of inventory cost influences the players’ strategies. Assuming risk-averse feature of the designer and fully optimizing property of the interdictor with limited budget, the conditional-value-at-risk is employed to be involved in total cost. Using special order sets of type two and duality role, the linearized tri-level problem is solved by column-and-constraint generation and benders decomposition algorithms in terms of small-sized instances. In terms of larger-sized instances, we also contribute to prior studies by hybridizing corresponding algorithms with bio-geography based optimization method. Another non-trivial extension of our work is to define adapted stochastic measures based on the proposed mean-risk tri-level formulation. Borrowing instances from prior papers, the computational results indicate the managerial insights on players’ decisions, the model’s efficiency and performance of the algorithms.Sat, 22 Feb 2020 20:30:00 +0100Productivity Improvement through Line Balancing by Using Simulation Modeling
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The typical problems facing garment manufacturers are long production lead time, bottlenecking, and low productivity. The most critical phase of garment manufacturing is the sewing phase, as it generally involves a number of operations or for the simple reason that it’s labor intensive. In assembly line balancing, allocation of jobs to machines is based on the objective of minimizing the workflow among the operators, reducing the throughput time as well as the work in progress and thus increasing the productivity. Sharing a job of work between several people is called division of labor. Division of labor should be balanced equally by ensuring the time spent at each station approximately the same. Each individual step in the assembly of product has to be analyzed carefully, and allocated to stations in a balanced way over the available workstations. Each operator then carries out operations properly and the work flow is synchronized. In a detailed work flow, synchronized line includes short distances between stations, low volume of work in process, precise of planning of production times, and predictable production quantity. This study deals with modeling of assembly line balancing by combining both manual line balancing techniques with computer simulation to find the optimal solution in the sewing line of Almeda textile plc so as to improve productivity. In this research arena software, is employed to model and measure the performance of the existing and proposed sewing line of the federal police trousers sewing line model. For each operation, the researchers have taken 15 sampling observations using stopwatch and recorded the result. All the collected data are statistically analyzed with arena input analyzer for statistical significance and determination of expressions to be used to the simulation modeling; SAM is also calculated for these operations to be used to the manual line balancing. An existing systems simulation model is developed and run for 160 replications by the researchers to measure the current performance of the system in terms of resource utilization, WIP, and waiting time. The existing systems average utilization is 0.53 with a line efficiency of 42%. This study has developed a new Sewing assembly line model which has increased the system utilization to 0.69 at a line efficiency of 58.42% without incurring additional cost.Sat, 29 Feb 2020 20:30:00 +0100A note on "An interval type-2 fuzzy extension of the TOPSIS method using alpha cuts"
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The technique for order of preference by similarity to ideal solution (TOPSIS) is a method based on the ideal solutions in which the most desirable alternative should have the shortest distance from positive ideal solution and the longest distance from negative ideal solution. Depending on type of evaluations or method of ranking, different approaches have been proposing to calculate distances in the TOPSIS method. In a recent paper, Dymova et al. (2015) extended the TOPSIS approach using interval type 2 fuzzy sets (IT2FSs) in which distances were calculated using alpha cuts. When investigating their paper, we found out that the extended method has some drawbacks such that it leads to the incorrect calculations and results when solving an IT2FSs-based multi-criteria decision making (MCDM) problem. In this note, the corrected version of extended TOPSIS method is being presented to eliminate its limitations. In order to show effectiveness and possibility of the proposed approach, it is also implemented in two illustrative examples and one case study. The results have showed that the optimal alternative obtained by the corrected TOPSIS approach has the similar rank to the others, whereas it is different from the results of existing TOPSIS approach.Sat, 22 Feb 2020 20:30:00 +0100Optimal Localization of Shopping Centers Using Metaheuristic Genetic Algorithm
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Efficiency and effectiveness is of importance for selection and localization. There should be regular methodology for targeting in the market by several methods. There is a necessity to have clear study for selection. In the current research, it has been studied the optimal localization at shopping centers. If there is not accuracy and validity, there will be achieved negative results for these centers such as high costs. Nowadays, these centers have turned into a part of consumer life. Today, they have penetrated consumers behavior and impacted on marketing mix. We can understand the importance of them from real shopping to window -shopping. As a meta-heuristic algorithm that inspired by natural systems, genetic algorithm has been used for problem salving as a mathematic model. The nature of genetic algorithm, which has created a relationship between humanity science and mathematics, is the reason for using it in the research. Given developed indices, Selected Iranian cities were selected for this study. Findings of the research showed that we can achieve accurate results with metaheuristic methods. The research is an applied research in terms of purpose, which is to develop applied knowledge in a certain field. Sat, 29 Feb 2020 20:30:00 +0100Optimal Use of Social Media From the Perspective of Brand Equity in Startups with a Data Approach
http://www.qjie.ir/article_673530_0.html
The purpose of this study is to identify the effective factors of optimal use of social media in the brand equity of startup companies. To this end, the researcher collected the required data using snowball sampling, protocol design, and exploratory interviews with sixteen university experts, the industry in this field, and senior managers of accelerator companies and startups. Maxqda 18 software was used to analyze the interviews. In the open coding process, the researcher first identified 170 codes and categorized them into 8 categories. Then, based on the theoretical literature and using the opinion of academic experts in axial coding based on Strauss and Corbin paradigm model, the relevant model was extracted and finally the selective coding was performed. To evaluate the validity of coding, Peer check method, the member check method and reliability by Field note were conducted. The results indicate that the main phenomena is using social media in startups and the communicational dimension as causal factors, cognitive dimension, and attitude in the position of strategies, brand characteristics as background factors, relational dimension, and rules and regulations as intervening factors and finally behavioral dimension were obtained as the consequences of the model.Mon, 05 Mar 2018 20:30:00 +0100Hybrid Teaching-Learning-Based Optimization and Harmony Search for Optimum Design of Space Trusses
http://www.qjie.ir/article_667916_1133638.html
The Teaching-Learning-Based Optimization (TLBO) algorithm is a new meta-heuristic algorithm which recently received more attention in various fields of science. The TLBO algorithm divided into two phases: Teacher phase and student phase; In the first phase a teacher tries to teach the student to improve the class level, then in the second phase, students increase their level by interacting among themselves. But, due to the lack of additional parameter to calculate the distance between the teacher and the mean of students, it is easily trapped at the local optimum and make it unable to reach the best global for some difficult problems. Since the Harmony Search (HS) algorithm has a strong exploration and it can explore all unknown places in the search space, it is an appropriate complement to improve the optimization process. Thus, based on these algorithms, they are merged to improve TLBO disadvantages for solving the structural problems. The objective function of the problems is the total weight of whole members which depends on the strength and displacement limits. Indeed, to avoid violating the limits, the penalty function applied in the form of stress and displacement limits. To show the superiority of the new hybrid algorithm to previous well-known methods, several benchmark truss structures are presented. The results of the hybrid algorithm indicate that the new algorithm has shown good performance.Sat, 29 Feb 2020 20:30:00 +0100Developing Fuzzy Tool Capability measurement system analysis
http://www.qjie.ir/article_671446_0.html
Due to the existing competitive environment of global economy, many companies allocate their major financial and human resources to quality improvement. Since, using measurement tool is an essential component in quality analysis and highly depends on quality of measurement systems and their results; measurement systems applications after calibration are the most efficient methods in real operations. Thus, inherent changes of measurement tools can be studied by computing capability index of measurement tools. This paper aims to develop a fuzzy model for computing capability. Fuzzy model for computing capability (Cg ،Cgk) with data in the form of fuzzy triangular and trapezoidal numbers using MATLAB is developed and then a case study applying proposed method is presented. Finally, we compare presented results with classical outcomes and prove that fuzzy environment gives more flexibility, rather than classical environment.Sat, 22 Feb 2020 20:30:00 +0100A new mathematical model for the green vehicle routing problem by considering a bi-fuel mixed ...
http://www.qjie.ir/article_671447_0.html
This paper formulates a mathematical model for the Green Vehicle Routing Problem (GVRP), incorporating bi-fuel (natural gas and gasoline) pickup trucks in a mixed vehicle fleet. The objective is to minimize overall costs relating to service (earliness and tardiness), transportation (fixed, variable and fuel), and carbon emissions. To reflect a real-world situation, the study considers: (1) a comprehensive fuel consumption function with a soft time window, and (2) an en-route fuel refueling option to eliminate the constraint of driving range. A linear set of valid inequalities for computing fuel consumption were introduced. In order to validate the presented model, first, the model is solved for an illustrative example. Then each component of cost objective function is considered separately so as to investigate the effects of each part on the obtained solutions and the importance of vehicles speed on transportation strategies. Computational analysis shows that, despite the limitation of an appropriate service infrastructure, the proposed model demonstrated an average reduction of 44%, 6% and 5% in carbon emission costs, total distribution costs, and transportation costs respectively. Moreover, the study found paradoxical effects of average speed, suggesting the need to manage trade-offs: while higher speeds reduced service costs, they increased carbon emission costs. In the next stage, some experiments modified from the literature are solved. According to these experiments, in all instances greater objective function values for Gasoline vehicles are gained. The difference in the carbon emission objective is also significant, with an average of 44.23% increase. Finally, managerial and institutional implications are discussed.Sat, 22 Feb 2020 20:30:00 +0100Representing a Model for Road Mapping in Emerging Sciences Case Study: Technology Road map of ...
http://www.qjie.ir/article_673168_0.html
One of the solutions for organizations to succeed in highly competitive markets is to move toward emerging sciences. These areas provide many opportunities, but, if organizations do not meet requirements of emerging sciences, they may fail and eventually, may enter a crisis. In this matter, one of the important requirements is to develop suitable roadmaps in variety fields such as strategic, capability, product, technology and etc. In this subject, it should be mentioned that there are connections among types of roadmaps, therefore, organizations need to understand these relations. According to this, we propose a model which describes relations among the roadmaps based on braid theory and appropriate methods for developing those roadmaps. The validity of developed model was conducted through the Delphi method. Additionally, we illustrate a to design a roadmap and implement it in quantum computing as an emerging science.Sat, 30 May 2020 19:30:00 +0100Machine scheduling for multitask machining
http://www.qjie.ir/article_673169_0.html
Multitasking is an important part of today’s manufacturing plants. Multitask machine tools are capable of processing multiple operations at the same time by applying a different set of part and tool holding devices. Mill-turns are multitask machines with the ability to perform a variety of operations with considerable accuracy and agility. One critical factor in simultaneous machining is to create a schedule for different operations to be completed in minimum make-span. A Mixed Integer Linear Programming (MILP) model is developed to address the machine scheduling problem. The adopted assumptions are more realistic when compared with the previous models. The model allows for processing multiple operations simultaneously on a single part; parts are being processed on the same setup and multiple turrets can process a single operation of a single job simultaneously performing multiple depths of cut. A Simulated Annealing algorithm with a novel initial solution and assignment approach is developed to solve large instances of the problem.Sat, 30 May 2020 19:30:00 +0100Online Distribution and Load Balancing Optimization Using the Robin Hood and Johnson Hybrid ...
http://www.qjie.ir/article_673174_0.html
Proper planning of assembly lines is one of the production managers’ concerns at the tactical level so that it would be possible to use the machine capacity, reduce operating costs and deliver customer orders on time. The lack of an efficient method in balancing assembly line can create threatening problems for manufacturing organizations. The use of assembly line balancing methods cannot balance load distribution on the assembly line which can cause higher depreciation of machinery heir related problems in the assembly line. In the present paper Robin Hood and Johnson algorithm combined approach is used for the problem of load distribution and optimized online load balance, based on the optimized order of works on the assembly line for polymer cover print in Iran Plot Company the results of which are analyzed in terms of creating load balance in the assembly line. The results that we have obtained in the present study include the uniform load distribution of orders to the machines and the presence of reservations and backup machine that causes the production process to continue with a proper sequence and the priority without any interruption.Sun, 31 May 2020 19:30:00 +0100Planning for Medical Emergency Transportation Vehicles during Natural Disasters
http://www.qjie.ir/article_673176_0.html
One of the main critical steps that should be taken during natural disasters is the assignment and distribution of resources among affected people. In such situations, this can save many lives. Determining the demands for critical items (i.e., the number of injured people) is very important. Accordingly, a number of casualties and injured people have to be known during a disaster. Obtaining an acceptable estimation of the number of casualties adds to the complexity of the problem. In this paper, a location-routing problem is discussed for urgent therapeutic services during disasters. The problem is formulated as a bi-objective Mixed-Integer Linear Programming (MILP) model. The objectives are to concurrently minimize the time of offering relief items to the affected people and minimize the total costs. The costs include those related to locations and transportation means (e.g., ambulances and helicopters) that are used to carry medical personnel and patients. To address the bi-objectiveness and verify the efficiency and applicability of the proposed model, the ε-constraint method is employed to solve several randomly-generated problems with CLEPX solver in GAMS. The obtained results include the objective functions, the number of the required facility, and the trade-offs between objectives. Then, the parameter of demands (i.e., number of casualties), which has the most important role, is examined using a sensitivity analysis and the managerial insights are discussed.Sun, 31 May 2020 19:30:00 +0100Solving a Multi-Item Supply Chain Network Problem by Three Meta-heuristic Algorithms
http://www.qjie.ir/article_673183_0.html
The supply chain network design not only assists organizations production process (e.g.,plan, control and execute a product’s flow) but also ensure what is the growing need for companies in a longterm. This paper develops a three-echelon supply chain network problem including multiple plants, multiple distributors, and multiple retailers with amulti-mode demand satisfaction policy inside of production planning and maintenance. The problem is formulated as a mixed-integer linear programming model. Because of its NP-hardness, three meta-heuristic algorithms(i.e., tabu search, harmony search and genetic algorithm) are used to solve the given problem. Also, theTaguchi method is used to choose the best levels of the parameters of the proposedmeta-heuristic algorithms. The results show that HS has abetter solution quality than two other algorithms.Sun, 31 May 2020 19:30:00 +0100A hybrid Unconscious Search algorithm for mixed-model assembly line balancing problem with ...
http://www.qjie.ir/article_673184_0.html
Due to the variety of products, simultaneous production of different models has an important role in production systems. Moreover, considering the realistic constraints in designing production lines attracted a lot of attentions in recent researches. Since the assembly line balancing problem is NP-hard, efficient methods are needed to solve this kind of problems. In this study, a new hybrid method based on unconscious search algorithm (USGA) is proposed to solve mixed-model assembly line balancing problem considering some realistic conditions such as parallel workstation, zoning constraints, sequence dependent setup times and learning effect. This method is a modified version of the unconscious search algorithm which applies the operators of genetic algorithm as the local search step. Performance of the proposed algorithm is tested on a set of test problems and compared with GA and ACOGA. The experimental results indicate that USGA outperforms GA and ACOGA.Sun, 31 May 2020 19:30:00 +0100A Public Bicycle Sharing System considering middle stations in which the users can stop before ...
http://www.qjie.ir/article_673365_0.html
Recently, public bicycle sharing system (PBSS) has become one of the most favorite urban transportation systems that can help governments to decrease environmental problems such as pollution and traffic. This paper studies a sharing system that includes two types of stations. The first category contains stations that users can rent or return back bicycles and each bicycle can be rented by any new user who arrives to the stations. The second group is the stations which are near shopping centers, historical and other places that users and tourists can stop and visit them. These stations are used only for parking the rented bicycles for a period of time and after that, the users must ride their bicycles and turn them back to their destination stations. After discussing the network of the model under the closed Jackson network, the Mean Value Analysis (MVA) method will be used to calculate the mean queue of each station and analyzing the proposed model.Sat, 06 Jun 2020 19:30:00 +0100Overcoming the uncertainty in a research reactor LOCA in level-1 PSA; Fuzzy based ...
http://www.qjie.ir/article_674014_0.html
Probabilistic safety assessment (PSA) which plays a crucial role in risk evaluation is a quantitative approach intended to demonstrate how a nuclear reactor meets the safety margins as part of the licensing process. Despite PSA merits, some shortcomings associated with the final results exist. Conventional PSA uses crisp values to represent the failure probabilities of basic events. This causes a high level of uncertainty due to the inherent imprecision and vagueness of failure input data. In this paper, to tackle this imperfection, a fuzzy approach is employed with fault tree analysis and event tree analysis. Thus, instead of using the crisp values, a set of fuzzy numbers is applied as failure probabilities of basic events. Hence, in the fault tree and event tree analysis, the top events and the end-states frequencies are treated as fuzzy numbers. By introducing some fuzzy importance measures the critical components which contribute maximum to the system failure and total uncertainty are identified. As a practical example, under redesign Iranian heavy water research reactor loss of coolant accident is studied. The results show that the reactor protection system has the largest index in sequences lead to a core meltdown. In addition, the emergency core cooling system has a main role in preventing abnormal conditions.Mon, 29 Jun 2020 19:30:00 +0100Performance Measurement and Improvement of Healthcare Service Using Discrete Event Simulation ...
http://www.qjie.ir/article_674015_0.html
This paper deals with the service performance analysis and improvement using discrete event simulation has been used. The simulation of the health care has been done by arena master development 14-version software. The performance measurement for this study are patients output, service rate, service efficiency and it is directly related to waiting time of patients in each service station, work in progress, resource utilization. Simulation model was building for Bahir Dar clinic and then, prepared the proposed model for the system. Based on the simulation model run result, the output of the existing healthcare service system is low due to presence of bottlenecks on the service system. Moreover, the station with the largest queue and high resource utilization are identified as a bottleneck. The bottlenecks, which have identified are reduced by using reassigning the existing resources and add new resources and merging the similar services, which has under low resource utilization (nurses). Finally, the researchers have proposed a developed model from different scenarios. Moreover, the best scenario is developed by combining scenario 2 and 3. And then, service efficiency of the healthcare has increased by 9.86 percent, the work in progress (WIP) are reduced by 3 patients from the system and the service capacity of the system is increased 34 to 40 patients per day due to the reduction of bottleneck stations.Mon, 29 Jun 2020 19:30:00 +0100Developing a risk management model for banking software development projects based on fuzzy ...
http://www.qjie.ir/article_674017_0.html
Risk management is one of the most influential parts of project management that has a major impact on the success or failure of projects. Due to the increasing use of information technology (IT) systems in all fields and the high failure rate of IT projects in software development and production, it is essential to effectively manage these projects is essential. Therefore, this study is aimed to design a risk management model that seeks to manage the risk of software development projects based on the key criteria of project time, cost, quality and scope. This is presented after making an extensive review of the literature and asking questions from experts in the field. In this regard, after identifying the risks and defining them based on the dimensions and indicators of software development projects, 22 features were identified to evaluate banking software projects. The data were collected for three consecutive years in the country's largest software development eco-system. According to Rough modelling, the most important variables affecting the cost, time, quality and scope of projects were identified and the amount of risk that a project may have in each of these dimensions was shown. Since traditional scales cannot provide the accurate estimation of project risk assessment under uncertainty, the indexes were fuzzy. Finally, the fuzzy expert system was designed by MATLAB software that showed the total risk of each project. To create a graphical user interface, the MATLAB software GUIDE was used. The system can predict the risks of each project before each project begins and helps project managers be prepared to deal with these risks and consider ways to prevent the project from failing. The results showed that quality and time risks were more important than cost and scope risks and had a greater impact on total project deviation.Mon, 29 Jun 2020 19:30:00 +0100