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Records with Subject: Planning & Scheduling
Showing records 1177 to 1201 of 1406. [First] Page: 1 45 46 47 48 49 50 51 52 53 Last
Optimal Scheduling of Virtual Power Plant Based on Latin Hypercube Sampling and Improved CLARA Clustering Algorithm
Wensi Cao, Shuo Wang, Mingming Xu
February 21, 2023 (v1)
Keywords: carbon trading, improved CLARA algorithm, Latin hypercube sampling, time-of-use tariffs, virtual power plant
In the context of the “Carbon peak, Carbon neutral” target, the introduction of carbon trading and the connection of new energy generation such as wind power and photovoltaics to the power grid have become important means to achieve a reduction to low carbon emissions. To this end, a virtual optimization model is established to take into account both low-carbon and economic aspects. Firstly, based on the basic concept of a virtual power plant, a virtual power plant model containing wind power, photovoltaic power, a gas turbine, and energy storage is established. Then, considering the uncertainty factors of wind power and PV power generation, Latin hypercube sampling (LHS) is used to simulate wind power and PV output scenarios, combined with the improved CLARA clustering algorithm to reduce the scenarios to form a classical scenario set to reduce the influence of wind power and PV output volatility. Finally, a carbon-trading mechanism and time-sharing tariff are introduced, and the mode... [more]
An Improved Arc Flow Model with Enhanced Bounds for Minimizing the Makespan in Identical Parallel Machine Scheduling
Anis Gharbi, Khaled Bamatraf
February 21, 2023 (v1)
Keywords: identical parallel machines, improved arc flow, integer programming, Scheduling, variable neighborhood search
In this paper, an identical parallel machine problem was considered with the objective of minimizing the makespan. This problem is NP-hard in the strong sense. A mathematical formulation based on an improved arc flow model with enhanced bounds was proposed. A variable neighborhood search algorithm was proposed to obtain an upper bound. Three lower bounds from the literature were utilized in the improved arc flow model to improve the efficiency of the mathematical formulation. In addition, a graph compression technique was proposed to reduce the size of the graph. As a consequence, the improved arc flow model was compared with an arc flow model from the literature. The computational results on benchmark instances showed that the improved arc flow model outperformed the literature arc flow model at finding optimal solutions for 99.97% of the benchmark instances, with the overall percentage of the reduction in time reaching 87%.
The Planning Method of the Multi-Energy Cloud Management Platform with Key Technologies and P2P Trade of Prosumers
Junfang Li, Yue Xing, Xuejin Huang, Donghui Zhang
February 21, 2023 (v1)
Keywords: cloud platform, common information model (CIM), energy management system (EMS), multi-energy system, peer-to-peer (P2P)
To build a multi-energy cloud platform with the distributed generation, energy storage, micro-grid, flexible load, electric vehicle piles for high efficiency application is of great significance. In order to manage the resources for dispatching and trading in the cloud platform, this paper solves three problems. Firstly, to present the cloud platform planning method. The modelling and linear optimization algorithm for the prosumer’s self-balanced to minimize the cost with trading quantity and random bidding price are proposed. Secondly, the key technologies to realize the information collection and interaction, and data model management are summarized on the basis of the demonstration project, faced to be urgently solved. Thirdly, P2P trade for small and medium scaled communities affected by grid’s time-of-use tariff for prosumers are discussed. The MATLAB simulation with the bidding price following uniformly distributed sampling is taken to analyze the consumers’ benefits and behavior... [more]
Filling Process Optimization through Modifications in Machine Settings
Yanmei Cui, Xupeng Zhang, Jing Luo
February 21, 2023 (v1)
Keywords: bottle filling, machine scheduling, mathematical modeling, one-dimensional rules, process optimization
In this paper, a mathematical model is developed for the modified settings of an automatic filling machine to minimize the filling time of orders for different volumes of dairy product and flavors. The linear programming model is solved using the Simplex method to find an optimal solution to the optimization problem. The results of the model are used for sequencing the processing of orders using one-dimensional rules with the aim of obtaining an optimal sequence for the most valued performance measure. The comparative analysis of the one-dimensional rules showed that Shortest Processing Time (SPT) is better than the other rules for minimization of the average time past due. Additionally, the results of the model for the new machine settings, when compared with previous similar studies, yielded encouraging results.
A Decision-Making Model for Predicting Technology Adoption Success
Farzad Tahriri, Maryam Mousavi, Hadi Galavi, Shahryar Sorooshian
February 21, 2023 (v1)
Keywords: advanced manufacturing technology (AMT), flexible manufacturing technology (FMT), fuzzy Delphi method (FDM), fuzzy inference system (FIS), multiple-attribute decision-making (MADM) model
Advanced manufacturing technology (AMT) has the potential to significantly improve manufacturing performance and boost competitiveness in the global market. Investment in AMT remains a promising but potentially risky venture due to the numerous factors that must be considered before the full benefits of implementing a new technology can be realized. To respond to the reported risks and uncertainties, such as those revealed in the recent industrial revolution, it is very important to identify and classify the critical factors that can influence the success of AMT adoption early in the planning stage. Based on an extensive review of relevant literature, 32 critical factors are identified and classified into ten categories in this paper. A new multiple-input single-output (MISO) model is developed by combining the fuzzy Delphi method (FDM) and the fuzzy inference system (FIS) based on the objectives defined. The FDM is used to determine the critical factors, and the FIS addresses the gene... [more]
A Modified FMEA Approach to Predict Job Shop Disturbance
Yongtao Qiu, Hongtao Zhang
February 21, 2023 (v1)
Keywords: disturbance prediction, FAHP, FMEA, job shop, production
Failure modes and effects analysis (FMEA) is a systematic approach that focuses on evaluating critical disturbances in a system. However, traditional FMEA has its own drawbacks, such as invalid computations and ambiguous priority definitions, which lead to many constraints in the application of complex production processes, especially in job shops with various resources. Therefore, this paper proposes an analytic disturbance prediction method for job shop with multiple resources and multiple evaluation indexes, which combines the vector computing techniques, FMEA, and fuzzy analytic hierarchy process (FAHP). In contrast to other work, this paper focuses on the establishment of FMEA mathematical model to improve the readability of multi-resource disturbance risk results. To this end, the projection of the disturbance vector is visualized to reduce repeated calculation results, triangles and trapezoids are used as membership functions to improve the accuracy of weight, and the differenti... [more]
Evaluating the Performance of a Safe Insulin Supply Chain Using the AHP-TOPSIS Approach
Mona Haji, Laoucine Kerbache, Tareq Al-Ansari
February 20, 2023 (v1)
Keywords: drug counterfeit, insulin safety, pharmaceutical supply chain, traceability technology
People with type 1 diabetes require insulin, a lifesaving and essential medication, to maintain their blood sugar levels below dangerous levels. Unfortunately, the insulin industry faces supply and affordability issues, and patients and their families face an enormous burden. As a result of high prices and lack of availability, individuals are turning to other options for purchasing insulin, such as online pharmacies, which may or may not be legitimate. Despite the necessity of safe insulin for diabetics in the legitimate Pharmaceutical Supply Chain (PSC), few researchers have considered implementing strategies to maximize patient safety for purchasing insulin. Therefore, the current research seeks to bridge this gap and provide cohesive information on overcoming this challenge and maximizing insulin safety. This study employs a Multi-Criteria Decision-Making (MCDM) model that combines Supply Chain Operations Reference (SCOR) metrics, Analytic Hierarchy Process (AHP), and Technique for... [more]
S-Velocity Profile of Industrial Robot Based on NURBS Curve and Slerp Interpolation
Guirong Wang, Fei Xu, Kun Zhou, Zhihui Pang
February 20, 2023 (v1)
Keywords: NURBS curve, quaternion, S-velocity planning, Slerp interpolation
This paper presents a novel algorithm for industrial robot trajectory planning based on the NURBS(Non-Uniform Rational B-Spline) curve and Slerp interpolation aiming at the problems that the trajectory of a six-axis industrial robot is not smooth enough in the operation process, the posture planning process is non-uniform, and the six-axis industrial robot starts and stops frequently. Firstly, aiming at the first problem, the trajectory planning algorithm based on the NURBS curve is presented to improve the smoothness of the trajectory curve. Combined with Slerp posture planning based on quaternion description, which realizes the uniform change of posture on the robot’s end-effector. Secondly, aiming at the second problem, the S-velocity planning algorithm is presented in the interpolation interval of the robot, which realizes the operation process of complex curves continuously, and improves the operation quality. Finally, this paper uses Bernoulli’s lemniscate as the incentive trajec... [more]
A Novel CSAHP Approach to Assess the Priority of Maintenance Work Outsourced by a Metro Company
Sung-Neng Peng, Chien-Yi Huang, Hwa-Dong Liu
February 17, 2023 (v1)
Keywords: consider sensitivity and analytic hierarchy process, metro system, outsourced maintenance, power supply system
To lower maintenance costs and improve a metro company’s competitiveness, this research came up with an innovative technique using a considering sensitivity and analytic hierarchy process (CSAHP). Along with interviews with managers and workers at the Taipei Rapid Transit Corporation, this study was able to undertake quantitative analysis. To determine which subsystems and metro lines should be prioritized for outsourcing based on the CSAHP framework, we used the criterium decision plus (CDP) program. This research adds to the existing body of knowledge by advancing the existing analytic hierarchy process (AHP) technique and recommending the CSAHP strategy for assessment. According to the findings, the power supply system was the most in need of outsourcing, followed by air conditioning, firefighting, and elevator systems. When considering which of the four metro lines to outsource first, the blue line came out on top, followed by the red, green, and brown lines. By prioritizing the ou... [more]
Designing Dispatching Rules via Novel Genetic Programming with Feature Selection in Dynamic Job-Shop Scheduling
Adilanmu Sitahong, Yiping Yuan, Ming Li, Junyan Ma, Zhiyong Ba, Yongxin Lu
February 17, 2023 (v1)
Keywords: dispatching rules, dynamic job shop scheduling (DJSS), feature selection, genetic programming (GP)
Genetic Programming (GP) has been widely employed to create dispatching rules intelligently for production scheduling. The success of GP depends on a suitable terminal set of selected features. Specifically, techniques that consider feature selection in GP to enhance rule understandability for dynamic job shop scheduling (DJSS) have been successful. However, existing feature selection algorithms in GP focus more emphasis on obtaining more compact rules with fewer features than on improving effectiveness. This paper is an attempt at combining a novel GP method, GP via dynamic diversity management, with feature selection to design effective and interpretable dispatching rules for DJSS. The idea of the novel GP method is to achieve a progressive transition from exploration to exploitation by relating the level of population diversity to the stopping criteria and elapsed duration. We hypothesize that diverse and promising individuals obtained from the novel GP method can guide the feature... [more]
Behavioral Model Deployment for the Transportation Projects within a Smart City Ecosystem: Cases of Germany and South Korea
Olga Shvetsova, Anastasiya Bialevich, Jihee Kim, Mariia Voronina
February 17, 2023 (v1)
Keywords: behavioral model, Germany, key variables, project, smart city ecosystem, South Korea, transportation industry
This research focused on a behavioral model as a significant tangible enabler for smart city plans and initiatives across Asian and EU regions as per transportation projects. This study aimed to create a behavioral model to serve as a planning tool for policymakers, planners, and implementers of transportation initiatives in smart cities. The paper discusses the validity of the proposed model framework for fostering the diffusion of a successful smart city project transformation in a general smart city ecosystem and particularly within the transportation industry. The framework was verified using three different methods: literature review to give a speculative understanding of current smart city approaches; case studies from Germany and South Korea smart city ecosystems that were selected and applied against the behavioral model; and finally, desktop research (behavioral model) performed for smart city project development. As a result, the authors recognized key variables for deriving... [more]
Path Planning of Mobile Robots Based on an Improved Particle Swarm Optimization Algorithm
Qingni Yuan, Ruitong Sun, Xiaoying Du
February 17, 2023 (v1)
Keywords: differential evolution algorithm and self-adaption, Particle Swarm Optimization, path planning
Aiming at disadvantages of particle swarm optimization in the path planning of mobile robots, such as low convergence accuracy and easy maturity, this paper proposes an improved particle swarm optimization algorithm based on differential evolution. First, the concept of corporate governance is introduced, adding adaptive adjustment weights and acceleration coefficients to improve the traditional particle swarm optimization and increase the algorithm convergence speed. Then, in order to improve the performance of the differential evolution algorithm, the size of the mutation is controlled by adding adaptive parameters. Moreover, a “high-intensity training” mode is developed to use the improved differential evolution algorithm to intensively train the global optimal position of the particle swarm optimization, which can improve the search precision of the algorithm. Finally, the mathematical model for robot path planning is devised as a two-objective optimization with two indices, i.e.,... [more]
Urban Regional Building Energy Planning Model under the Guidance of Network Flow Theory
Jing Liu, Pengqiang Zheng, Yubao Zhan, Zhiguo Li, Zhaoxia Shi
February 17, 2023 (v1)
Keywords: BG iterative algorithm, building energy planning, minimum cost maximum flow, network flow theory, urban area
The satisfactory construction of regional building energy planning models is a key technology in effective energy allocation. At present, the selection of energy planning is only based on artificial judgment criteria, which leads to a high subjectivity in energy planning. This research innovatively introduces the network flow theory into the urban regional building energy planning model. Combined with the actual characteristics of regional building energy planning, the regional building energy planning model was constructed and the regional energy distribution mode was optimized. The model includes the energy supply layer, energy conversion layer, and energy demand layer. At the same time, the minimum cost and maximum flow problem of the model was solved with the help of the BG iterative algorithm. The model includes the energy supply layer, energy conversion layer, and energy demand layer. We used the BG iterative algorithm to solve the minimum cost and maximum flow problem of the mod... [more]
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]
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