Records with Subject: Planning & Scheduling
Showing records 1 to 25 of 217. [First] Page: 1 2 3 4 5 Last
Improved Hybrid Heuristic Algorithm Inspired by Tissue-Like Membrane System to Solve Job Shop Scheduling Problem
Xiang Tian, Xiyu Liu
October 13, 2022 (v1)
Keywords: hybrid heuristic algorithm, job shop scheduling problem, tissue-like membrane system
In real industrial engineering, job shop scheduling problem (JSSP) is considered to be one of the most difficult and tricky non-deterministic polynomial-time (NP)-hard problems. This study proposes a new hybrid heuristic algorithm for solving JSSP inspired by the tissue-like membrane system. The framework of the proposed algorithm incorporates improved genetic algorithms (GA), modified rumor particle swarm optimization (PSO), and fine-grained local search methods (LSM). To effectively alleviate the premature convergence of GA, the improved GA uses adaptive crossover and mutation probabilities. Taking into account the improvement of the diversity of the population, the rumor PSO is discretized to interactively optimize the population. In addition, a local search operator incorporating critical path recognition is designed to enhance the local search ability of the population. Experiment with 24 benchmark instances show that the proposed algorithm outperforms other latest comparative alg... [more]
Algorithmic Approaches to Inventory Management Optimization
Hector D. Perez, Christian D. Hubbs, Can Li, Ignacio E. Grossmann
January 24, 2022 (v1)
Keywords: inventory management, multi-echelon, reinforcement learning, stochastic programming, Supply Chain
An inventory management problem is addressed for a make-to-order supply chain that has inventory holding and/or manufacturing locations at each node. The lead times between nodes and production capacity limits are heterogeneous across the network. This study focuses on a single product, a multi-period centralized system in which a retailer is subject to an uncertain stationary consumer demand at each time period. Two sales scenarios are considered for any unfulfilled demand: backlogging or lost sales. The daily inventory replenishment requests from immediate suppliers throughout the network are modeled and optimized using three different approaches: (1) deterministic linear programming, (2) multi-stage stochastic linear programming, and (3) reinforcement learning. The performance of the three methods is compared and contrasted in terms of profit (reward), service level, and inventory profiles throughout the supply chain. The proposed optimization strategies are tested in a stochastic s... [more]
Optimal Production and Inventory Policy in a Multiproduct Bakery Unit
Belmiro P. M. Duarte, André M. M. Gonçalves, Lino O. Santos
January 24, 2022 (v1)
Keywords: food processing unit, inventory policy, multiproduct plant, optimal production policy
The problem of finding optimal production and inventory policies is crucial for companies of the food industry, especially those processing multiple products. Since companies are required to adopt the most efficient solutions to prosper, the operation at these optimal conditions can have an extensive impact on profit, resource allocation and product quality. We address the problem of finding the optimal production and inventory policy in a multiproduct bakery unit for two contexts: (i) deterministic consumption without inventory control; and (ii) stochastic consumption combined with delayed inventory control. A formulation is proposed for each of these two setups. The restrictions considered in the model framework are related to workforce availability, and the cost structure includes four components: (i) production cost; (ii) inventory cost; (iii) setup cost; and (iv) the cost due to the degradation of perceived quality. The problem is formulated as a Mixed Integer Linear Programming o... [more]
Optimal Cleaning Cycle Scheduling under Uncertain Conditions: A Flexibility Analysis on Heat Exchanger Fouling
Alessandro Di Pretoro, Francesco D’Iglio, Flavio Manenti
December 6, 2021 (v1)
Keywords: flexibility, fouling, heat exchanger, maintenance, Scheduling
Fouling is a substantial economic, energy, and safety issue for all the process industry applications, heat transfer units in particular. Although this phenomenon can be mitigated, it cannot be avoided and proper cleaning cycle scheduling is the best way to deal with it. After thorough literature research about the most reliable fouling model description, cleaning procedures have been optimized by minimizing the Time Average Losses (TAL) under nominal operating conditions according to the well-established procedure. For this purpose, different cleaning actions, namely chemical and mechanical, have been accounted for. However, this procedure is strictly related to nominal operating conditions therefore perturbations, when present, could considerably compromise the process profitability due to unexpected shutdown or extraordinary maintenance operations. After a preliminary sensitivity analysis, the uncertain variables and the corresponding disturbance likelihood were estimated. Hence, cl... [more]
Modified Multi-Crossover Operator NSGA-III for Solving Low Carbon Flexible Job Shop Scheduling Problem
Xingping Sun, Ye Wang, Hongwei Kang, Yong Shen, Qingyi Chen, Da Wang
October 14, 2021 (v1)
Keywords: co-evolution, flexible job shop scheduling problem, Genetic Algorithm, low carbon, multi-crossover operator, multi-objective optimization
Low carbon manufacturing has received increasingly more attention in the context of global warming. The flexible job shop scheduling problem (FJSP) widely exists in various manufacturing processes. Researchers have always emphasized manufacturing efficiency and economic benefits while ignoring environmental impacts. In this paper, considering carbon emissions, a multi-objective flexible job shop scheduling problem (MO-FJSP) mathematical model with minimum completion time, carbon emission, and machine load is established. To solve this problem, we study six variants of the non-dominated sorting genetic algorithm-III (NSGA-III). We find that some variants have better search capability in the MO-FJSP decision space. When the solution set is close to the Pareto frontier, the development ability of the NSGA-III variant in the decision space shows a difference. According to the research, we combine Pareto dominance with indicator-based thought. By utilizing three existing crossover operators... [more]
Integrating FMEA and the Kano Model to Improve the Service Quality of Logistics Centers
Ling-Lang Tang, Shun-Hsing Chen, Chia-Chen Lin
October 11, 2021 (v1)
Keywords: failure mode and effect analysis (FMEA), Kano model, logistics center, service failure, service quality
This study uses the logistics center of a large organic retail store in Taiwan to analyze service blueprint and workflow, identifying the potential points of failure and thus serving as a basis for quality improvement. The failure mode and effect analysis (FMEA) model is an effective problem prevention methodology that can easily interface with many engineering and reliability methods. The utilized method integrates the failure mode and effect analysis (FMEA) and the Kano model to explore the possible occurrence of failures in the internal workflow and services of the studied logistics center. A two-stage survey was conducted. In the first stage, an investigation was conducted by 20 logistics experts on the FMEA’s key service failures. In the second stage, a questionnaire was filled out by 220 store staff to summarize the logistics service quality factors found in the Kano model. The results show that the degree of attention and satisfaction in the priority improvement items when there... [more]
Task Scheduling Problem of Double-Deep Multi-Tier Shuttle Warehousing Systems
Xiangnan Zhan, Liyun Xu, Xufeng Ling
September 22, 2021 (v1)
Keywords: carbon emissions, double-deep multi-tier shuttle warehousing systems, NSGA-II, rearrangement operation, system efficiency, task scheduling
Double-deep multi-tier shuttle warehousing systems (DMSWS) have been increasingly applied for store-and-retrieval stock-keeping unit tasks, with the advantage of a reduced number of aisles and improved space utilization. Scheduling different devices for retrieval tasks to increase system efficiency is an important concern. In this paper, a Pareto optimization model of task operations based on the cycle time and carbon emissions is presented. The impact of the rearrangement operation is considered in this model. The cycle time model is converted into a flow-shop scheduling model with parallel machines by analyzing the retrieval operation process. Moreover, the carbon emissions of the shuttle in the waiting process, the carbon emissions of the lift during the free process, and the carbon emissions of the retrieval operation are considered in the carbon emissions model, which can help us to evaluate the carbon emissions of the equipment more comprehensively during the entire retrieval tas... [more]
Building Robust Closed-Loop Supply Networks against Malicious Attacks
Ding-Shan Deng, Wei Long, Yan-Yan Li, Xiao-Qiu Shi
September 22, 2021 (v1)
Keywords: closed-loop supply network, malicious attacks, multi-population evolutionary algorithm, robustness
With recent industrial upgrades, it is essential to transform the current forward supply networks (FSNs) into closed-loop supply networks (CLSNs), which are formed by the integration of forward and reverse logistics. The method chosen in this paper for building reverse logistics is to add additional functions to the existing forward logistics. This process can be regarded as adding reverse edges to the original directed edges in an FSN. Due to the limitation of funds and the demand for reverse flow, we suppose that a limited number of reverse edges can be built in a CLSN. To determine the transformation schemes with excellent robustness against malicious attacks, this paper proposes a multi-population evolutionary algorithm with novel operators to optimize the robustness of the CLSN, and this algorithm is abbreviated as MPEA-RSN. Then, both the generated and realistic SNs are taken as examples to validate the effectiveness of MPEA-RSN. The simulation results show that the index R, intr... [more]
A Smart Production Process for the Optimum Energy Consumption with Maintenance Policy under a Supply Chain Management
Shaktipada Bhuniya, Sarla Pareek, Biswajit Sarkar, Bimal Kumar Sett
September 21, 2021 (v1)
Keywords: backorder, flexible production rate, maintenance, marketing, smart production, supply chain management
In the current socio-economic situation, smart products are essential for daily life. Energy is a very much related matter to smart products. To buy a smart product, people mostly care about that smart product’s energy consumption and the price. There is always a tug-of-war between the price of the product and the energy consumption of that product. An energy-efficient smart production system is described in this study where the production is variable, and in the out-of-control state, it produces defective products. For prevention of the out-of-control state, preventive maintenance and restoration are used within the smart production system. The rework policy helps to profit from the defective products, and the warranty policy helps to motivate the users. This model applies an improved strategy to the production process and develops a new product that needs to be marketed. Finally, this model plays a vital role in creating smart products with moderate energy consumption at a minimal co... [more]
Risk Assessment of Investments in Projects of Production of Raw Materials for Bioethanol
Anatoliy Tryhuba, Taras Hutsol, Inna Tryhuba, Nataliia Pokotylska, Nataliia Kovalenko, Sylwester Tabor, Dariusz Kwasniewski
September 16, 2021 (v1)
Keywords: bioethanol, investor, project, raw material production, risk
The proposed approach to quantitative assessment of the risk of investor’s profit in projects for the production of raw materials for bioethanol involves the implementation of eight stages. It systematically takes into account the stochastic nature of many factors that determine the amount of investments in the project, as well as the stochastic nature of the market value of raw materials. The use of the proposed approach makes it possible to obtain an accurate assessment of the level of risk of investors in projects for the production of raw materials for bioethanol, taking into account the requirements of investors. Based on the use of the developed application software, stochastic models of profit of investors in projects for the production of raw materials for wheat bioethanol and patterns of changes in their risk for the Western region of Ukraine are obtained. It is established that with the growth of the minimum expected profit of investors of projects from 10 to 70$/ton, the pro... [more]
Integration and Evaluation of Intra-Logistics Processes in Flexible Production Systems Based on OEE Metrics, with the Use of Computer Modelling and Simulation of AGVs
Krzysztof Foit, Grzegorz Gołda, Adrian Kampa
July 29, 2021 (v1)
Keywords: AGV—Automated Guided Vehicles, DES—Discrete Event Simulation, FMS—Flexible Manufacturing Systems, Industry 4.0, OEE—Overall Equipment Efficiency, WCLcWorld Class Logistic
The article presents the problems connected with the performance evaluation of a flexible production system in the context of designing and integrating production and logistics subsystems. The goal of the performed analysis was to determine the parameters that have the most significant influence on the productivity of the whole system. The possibilities of using automated machine tools, automatic transport vehicles, as well as automated storage systems were pointed out. Moreover, the exemplary models are described, and the framework of simulation research related to the conceptual design of new production systems are indicated. In order to evaluate the system’s productivity, the use of Overall Equipment Efficiency (OEE) metrics was proposed, which is typically used for stationary resources such as machines. This paper aims to prove the hypothesis that the OEE metric can also be used for transport facilities such as Automated Guided Vehicles (AGVs). The developed models include the para... [more]
Stability of Optimal Closed-Loop Cleaning Scheduling and Control with Application to Heat Exchanger Networks under Fouling
Federico Lozano Santamaria, Sandro Macchietto
July 19, 2021 (v1)
Keywords: closed-loop scheduling, fouling, heat exchanger networks, optimal control and scheduling, scheduling stability
Heat exchanger networks subject to fouling are an important example of dynamic systems where performance deteriorates over time. To mitigate fouling and recover performance, cleanings of the exchangers are scheduled and control actions applied. Because of inaccuracy in the models, as well as uncertainty and variability in the operations, both schedule and controls often have to be revised to improve operations or just to ensure feasibility. A closed-loop nonlinear model predictive control (NMPC) approach had been previously developed to simultaneously optimize the cleaning schedule and the flow distribution for refinery preheat trains under fouling, considering their variability. However, the closed-loop scheduling stability of the scheme has not been analyzed. For practical closed-loop (online) scheduling applications, a balance is usually desired between reactivity (ensuring a rapid response to changes in conditions) and stability (avoiding too many large or frequent schedule changes... [more]
Automated Optimization for the Production Scheduling of Prefabricated Elements Based on the Genetic Algorithm and IFC Object Segmentation
Zhao Xu, Xiang Wang, Zezhi Rao
July 12, 2021 (v1)
Keywords: Genetic Algorithm, IFC standard, prefabrication, production schedule, segmentation
Background: With the ever-increasing availability of data and a higher level of automation and simulation, production scheduling in the factory for prefabrication can no longer be seen as an autonomous solution. Concepts such as building information modelling (BIM), graphic techniques, databases, and interface development as well as heightened emphasis on overall-process optimization topics increase the pressure to connect to and interact with interrelated tasks and procedures. Methods: The automated optimization framework detailed in this study intended to generate optimal schedule of prefabricated component production based on the manufacturing process model and genetic algorithm method. An extraction and segmentation approach based on industry foundation classes (IFC) for prefabricated component production is discussed. During this process, the position and geometric information of the prefabricated components are adjusted and output in the extracted IFC file. Then, the production p... [more]
Synthesis of European Union Biorefinery Supply Networks Considering Sustainability Objectives
Sanja Potrč, Lidija Čuček, Mariano Martin, Zdravko Kravanja
July 12, 2021 (v1)
Keywords: 2030 target, biorefinery supply network, European Union, mathematical programming, production of biofuels, Renewable and Sustainable Energy, sustainability profit
Increasing the use of renewable energy sources is one of the most important goals of energy policies in several countries to build a sustainable energy future. This contribution proposes the synthesis of a biorefinery supply network for a case study of the European Union (EU-27) under several scenarios based on a mathematical programming approach. Several biomass and waste sources, such as grains, waste oils, and lignocellulosics, are proposed to be utilized, and various biofuels including first, second, and third generations are produced such as bioethanol, green gasoline, biodiesel, Fischer Tropsch (FT) diesel, and hydrogen. The aim of this study is to evaluate the capabilities of EU-27 countries to be able to meet the Renewable Energy Directive (RED II) target regarding the share of renewable energy in the transport sector by 2030 in each Member State while not compromising the current production of food. A generic mathematical model has been developed for the multi-period optimizat... [more]
Quality Inspection Plan for Imperfect Production System with Assembly Configuration
Jyh-Wen Ho
June 21, 2021 (v1)
Keywords: assemble to order, imperfect production system, quality inspection
In this study, the model concerning a negative binomial sampling inspection plan is proposed and applied to an imperfect production system with assemble-to-order configuration, where the production system is subject to a Weibull deteriorating process and is operated under an in-control or an out-of-control state. The proposed model of this study contributes to developing an approach which can effectively integrate the considerations of the production system status, the defective rate, the working efficiency of employees, and the market demands with an aim to determine the optimal number of conforming items for inspection with minimum total cost, and the results can be practically applied to the assembly of products in various industries, especially for the prevalent Industry 4.0 in manufacturing.
An Agricultural Products Supply Chain Management to Optimize Resources and Carbon Emission Considering Variable Production Rate: Case of Nonperishable Corps
Mohammed Alkahtani, Muhammad Omair, Qazi Salman Khalid, Ghulam Hussain, Biswajit Sarkar
June 10, 2021 (v1)
Keywords: agri-supply chain management, eco-efficient production, imperfect production, optimal resources, variable production rate
The management of the man−machine interaction is essential to achieve a competitive advantage among production firms and is more highlighted in the processing of agricultural products. The agricultural industry is underdeveloped and requires a transformation in technology. Advances in processing agricultural products (agri-product) are essential to achieve a smart production rate with good quality and to control waste. This research deals with modelling of a controllable production rate by a combination of the workforce and machines to minimize the total cost of production. The optimization of the carbon emission variable and management of the imperfection in processing makes the model eco-efficient. The perishability factor in the model is ignored due to the selection of a single sugar processing firm in the supply chain with a single vendor for the pragmatic application of the proposed research. A non-linear production model is developed to provide an economic benefit to the firms in... [more]
Sustainable Production−Inventory Model in Technical Cooperation on Investment to Reduce Carbon Emissions
JiaLiang Pan, Chui-Yu Chiu, Kun-Shan Wu, Hsiu-Feng Yen, Yen-Wen Wang
May 26, 2021 (v1)
Keywords: carbon cap-and-trade, carbon tax, sustainable production–inventory model
Carbon cap-and-trade and carbon offsets are common and important carbon emission reduction policies in many countries. In addition, carbon emissions from business activities can be effectively reduced through specific capital investments in green technologies. Nevertheless, such capital investments are costly and not all enterprises can afford these investments. Therefore, if all members of a supply chain agree to share the investments in the facilities, the supply chain can reduce carbon emissions and generate more profit. Under carbon cap-and-trade and carbon tax policies, this study proposes a production−inventory model in which the buyer and vendor in the integrated supply chain agree to co-invest funds to reduce carbon emissions. We planned to integrate production, delivery, replenishment, and technology to reduce carbon emissions so as to maximize the total profit of the supply chain system. Several examples are simulated and the sensitivity analysis of the main parameters is car... [more]
Minimizing Tardiness Penalty Costs in Job Shop Scheduling under Maximum Allowable Tardiness
Jae-Gon Kim, Hong-Bae Jun, June-Young Bang, Jong-Ho Shin, Seong-Hoon Choi
May 25, 2021 (v1)
Keywords: job shop scheduling, maximum allowable tardiness, probabilistic dispatching rules, semiconductor, tardiness penalty
In many manufacturing or service industries, there exists maximum allowable tardiness for orders, according to purchase contracts between the customers and suppliers. Customers may cancel their orders and request compensation for damages, for breach of contract, when the delivery time is expected to exceed maximum allowable tardiness, whereas they may accept the delayed delivery of orders with a reasonable discount of price within maximum allowable tardiness. Although many research works have been produced on the job shop scheduling problem relating to minimizing total tardiness, none of them have yet considered problems with maximum allowable tardiness. In this study, we solve a job shop scheduling problem under maximum allowable tardiness, with the objective of minimizing tardiness penalty costs. Two kinds of penalty costs are considered, i.e., one for tardy jobs, and the other for canceled jobs. To deal with this problem within a reasonable time at actual production facilities, we p... [more]
A Joint Optimization Strategy of Coverage Planning and Energy Scheduling for Wireless Rechargeable Sensor Networks
Cheng Gong, Chao Guo, Haitao Xu, Chengcheng Zhou, Xiaotao Yuan
April 30, 2021 (v1)
Keywords: coverage optimization, Particle Swarm Optimization, queuing game, virtual force, wireless rechargeable sensor network
Wireless Sensor Networks (WSNs) have the characteristics of large-scale deployment, flexible networking, and many applications. They are important parts of wireless communication networks. However, due to limited energy supply, the development of WSNs is greatly restricted. Wireless rechargeable sensor networks (WRSNs) transform the distributed energy around the environment into usable electricity through energy collection technology. In this work, a two-phase scheme is proposed to improve the energy management efficiency for WRSNs. In the first phase, we designed an annulus virtual force based particle swarm optimization (AVFPSO) algorithm for area coverage. It adopts the multi-parameter joint optimization method to improve the efficiency of the algorithm. In the second phase, a queuing game-based energy supply (QGES) algorithm was designed. It converts energy supply and consumption into network service. By solving the game equilibrium of the model, the optimal energy distribution str... [more]
Material Requirements Planning Using Variable-Sized Bin-Packing Problem Formulation with Due Date and Grouping Constraints
Dejan Gradišar, Miha Glavan
April 27, 2021 (v1)
Keywords: bin-packing problem, material requirements planning, mixed-integer linear programming
Correct planning is crucial for efficient production and best quality of products. The planning processes are commonly supported with computer solutions; however manual interactions are commonly needed, as sometimes the problems do not fit the general-purpose planning systems. The manual planning approach is time consuming and prone to errors. Solutions to automatize structured problems are needed. In this paper, we deal with material requirements planning for a specific problem, where a group of work orders for one product must be produced from the same batch of material. The presented problem is motivated by the steel-processing industry, where raw materials defined in a purchase order must be cut in order to satisfy the needs of the planned work order while also minimizing waste (leftover) and tardiness, if applicable. The specific requirements of the problem (i.e., restrictions of which work orders can be produced from a particular group of raw materials) does not fit the regular p... [more]
Decision-Making of Port Enterprise Safety Investment Based on System Dynamics
Jiachen Sun, Haiyan Wang, Jie Chen
April 27, 2021 (v1)
Keywords: decision-making, port enterprises, safety investment, SD
Safety is the premise of efficiency and effectiveness in the port operation. Safety investment is becoming a vital part of port operation in current era in order to overcome different types of hazards the port operation exposed to. This paper aims to improve the safety level of port operation through analyzing its influencing factors and exploring the interactions between the safety investment and system risk level. By analyzing the key factors affecting the port operation and their mutual relationship within a man−machine−environment−management system, a decision-making model of safety investment in port enterprise was established by system dynamics (SD). An illustration example and a sensitivity analysis were carried out to justify and validate the proposed model. The results show that increasing the total safety investment of port enterprises, improving the safety management investment on personnel, and strengthening the implementation effect of investment can improve the degree of... [more]
Carbon-Efficient Production Scheduling of a Bioethanol Plant Considering Diversified Feedstock Pelletization Density: A Case Study
Xinchao Li, Xin Jin, Shan Lu, Zhe Li, Yue Wang, Jiangtao Cao
April 16, 2021 (v1)
Keywords: bioethanol plant, carbon emission, dual-objective optimization, Scheduling
This paper presents a dual-objective optimization model for production scheduling of bioethanol plant with carbon-efficient strategies. The model is developed throughout the bioethanol production process. Firstly, the production planning and scheduling of the bioethanol plant’s transportation, storage, pretreatment, and ethanol manufacturing are fully considered. Secondly, the carbon emissions in the ethanol manufacturing process are integrated into the model to form a dual-objective optimization model that simultaneously optimizes the production plan and carbon emissions. The effects of different biomass raw materials with optional pelletization density and pretreatment methods on production scheduling are analyzed. The influence of demand and pretreatment cost on selecting a pretreatment method and total profit is considered. A membership weighted method is developed to solve the dual-objective model. The carbon emission model and economic model are integrated into one model for anal... [more]
Assessing Supply Chain Performance from the Perspective of Pakistan’s Manufacturing Industry Through Social Sustainability
Maryam Khokhar, Wasim Iqbal, Yumei Hou, Majed Abbas, Arooj Fatima
February 22, 2021 (v1)
Keywords: Pakistan, qualitative research, social sustainability, sustainable supply chain management (SSSCM)
The industry is gradually forced to integrate socially sustainable development practices and cross-social issues. Although researchers and practitioners emphasize environmental and economic sustainability in supply chain management (SCM). This is unfortunate because not only social sustainable development plays an important role in promoting other sustainable development programs, but social injustice at one level in the supply chain may also cause significant losses to companies throughout the chain. This article aimed to consolidate the literature on the responsibilities of suppliers, manufacturers, and customers and to adopt sustainable supply chain management (SSSCM) practices in the Pakistani industry to identify all possible aspects of sustainable social development in the supply chain by investigating the relationship between survey variables and structure. This work went beyond the limits of regulations and showed the status of maintaining sustainable social issues. Based on se... [more]
Exploring E-Waste Resources Recovery in Household Solid Waste Recycling
Muhammad Mobin Siddiqi, Muhammad Nihal Naseer, Yasmin Abdul Wahab, Nor Aliya Hamizi, Irfan Anjum Badruddin, Mohd Abul Hasan, Zaira Zaman Chowdhury, Omid Akbarzadeh, Mohd Rafie Johan, Sarfaraz Kamangar
February 22, 2021 (v1)
Keywords: household solid waste, metal recovery value, socio-economic benefits, waste composition of Karachi-Pakistan, waste management, waste recycling
The ecosystem of earth, the habitation of 7.53 billion people and more than 8.7 million species, is being imbalanced by anthropogenic activities. The ever-increasing human population and race of industrialization is an exacerbated threat to the ecosystem. At present, the global average waste generation per person is articulated as 494 kg/year, an enormous amount of household waste (HSW) that ultimately hits 3.71×1012 kg of waste in one year. The ultimate destination of HSW is a burning issue because open dumping and burning as the main waste treatment and final disposal systems create catastrophic environmental limitations. This paper strives to contribute to this issue of HSW management that matters to everyone’s business, specifically to developing nations. The HSW management system of the world’s 12th largest city and 24th most polluted city, Karachi, was studied with the aim of generating possible economic gains by recycling HSWs. In this regard, the authors surveyed dumping sites... [more]
Scheduling Two Identical Parallel Machines Subjected to Release Times, Delivery Times and Unavailability Constraints
Adel M. Al-Shayea, Mustafa Saleh, Moath Alatefi, Mageed Ghaleb
February 3, 2021 (v1)
Keywords: Cmax, delivery times, genetic algorithm (GA), Optimization, parallel machine scheduling, preventive maintenance, release times
This paper proposes a genetic algorithm (GA) for scheduling two identical parallel machines subjected to release times and delivery times, where the machines are periodically unavailable. To make the problem more practical, we assumed that the machines are undergoing periodic maintenance rather than making them always available. The objective is to minimize the makespan (Cmax). A lower bound (LB) of the makespan for the considered problem was proposed. The GA performance was evaluated in terms of the relative percentage deviation (RPD) (the relative distance to the LB) and central processing unit (CPU) time. Response surface methodology (RSM) was used to optimize the GA parameters, namely, population size, crossover probability, mutation probability, mutation ratio, and pressure selection, which simultaneously minimize the RPD and CPU time. The optimized settings of the GA parameters were used to further analyze the scheduling problem. Factorial design of the scheduling problem input v... [more]
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