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The planning of maintenance activities can hinder manufacturing operations in term of cost, quality and time, but it is necessary to ensure the availability of the production equipment to meet customer demands. We propose to model the function of maintenance tasks and production operations by the sum of the two costs under a set of constraints. As a method of resolution, we use genetic algorithms...
A spare part supply system for repairable spares in a repair shop is modeled as a set of heterogeneous parallel servers that have the ability to repair only certain types of repairables. The proposed model minimizes the total cost of holding inventory for spare parts, cost for backorder arising from downtime of the system due to the lack of spare parts and the cost of crosstraining for servers. Simulation-based...
Considering the effects of machine breakdown and preventative maintenance (PM)on production scheduling in flowshop manufacturing cells, this paper focuses on investigating the joint optimization problem of flowshop sequence-dependent manufacturing cell scheduling and PM. A joint model is proposed and it aims to find the optimal production sequence of job families and individual jobs within each family...
The paper deals with lighting road design. The demands on illuminance are defined in standard ČSN EN 13201 in case of Czech Republic. There are several parameters that a designer can change to get the optimal solution to fulfill the standard. The distance between pillars, their heights, the lamp overlap and tilt have to be defined. Such number of parameters make the optimization difficult. This paper...
Organizations related to infrastructure, such as utilities and railway companies, manage a large number of facilities, the failure of which can have a huge impact on society. The cost of maintaining these facilities is a combination of regular maintenance costs and urgent recovery costs. Generally, the urgent costs are much higher than regular costs. Regular maintenance work should result in fewer...
A mean-semi-variance portfolio optimization model with constraints of cardinality, investment quota, total capital and integer transaction is established, the model can reflect the transaction costs completely. Because the conventional genetic algorithm isn't easy to find feasible solution of portfolio optimization model, a stochastic repair method of an infeasible solution is proposed, which consists...
For the complex system subject to external detrimental factors and internal wear failures, both the proper protection and efficient maintenance activities on the system elements should be considered in order to maintain a desired level of system availability. A maintenance strategy consisting of preventive replacement and minimal repair is introduced, and the probability of destruction by external...
In the airline industry, the Aircraft Maintenance Routing (AMR) problem has been one of the great successes of operations research. The AMR problem is to determine a particular route for each aircraft to undergo different levels of maintenance checks. The objective is to minimize the total maintenance costs. In this study, our aim is to present a mathematical formulation for the AMR problem which...
In this paper, we will present a model for joint optimization of periodic inspection and inventory levels for a k-out-of-n system. The component failures follow a Non-Homogeneous Poisson Process and failed components can only be revealed at inspection times. We have two types of inspections; planned periodic inspections and non-planned opportunistic inspections. Opportunistic inspections are performed...
This paper proposes a condition based group maintenance policy for multi-component system. Condition of the components is defined in terms of Remaining Useful Life (RUL). Predicted RULs are always associated with some uncertainty. The RULs and associated uncertainty then affect the maintenance decision making. This work aims at obtaining optimal maintenance grouping of components at current planned...
For the optimization of multi-component system preventive maintenance, the group maintenance strategy was adopted to model and optimize periodic replacement tasks. Based on the analysis of system maintenance cost structure and composition, the mathematical models were established for expected maintenance cost per unit time. And a genetic algorithm based approach was developed to search for the optimal...
This study looks at the system availability optimization problem under different resource and design configuration constraints by applying Tabu-GA combination method. From the point of view of logistics engineering, availability optimization applied in the initial system development period, plays a key role to affect system reliability, system maintenance planning, logistics requirements, and related...
This paper presents a method for determining a minimal cost of a multi-state system subject to a corrective maintenance. The minimal cost is achieved by finding an optimal load distribution from a sequence of possible combinations. The cost considered is a combination of downtime cost (loss of productivity) and repair cost. The former is affected by a penalty value. The element failure rate depends...
The software project scheduling is a complicated problem. The risk and the cost of the software project can be controlled well by a remarkable scheduling. In this paper, an optimization model for Multi-Resource Constrained Project Scheduling is presented to reduce the duration and the cost. A genetic algorithm Base on the Genetic Algorithm is proposed. It gives the method of two sections coding, the...
Retrofit and optimization of low-temperature gas separation processes is a challenging task owing to complicated interactions between the core process (separation columns), refrigeration cycles, and the associated heat exchanger network. In this paper, the performance of cold section of an olefin plant is optimized. A comprehensive screening of all effective changes using genetic algorithm suggests...
The configuration of a repairable system directly affects its performance measures such as mean time between failures and steady state availability. Corrective, preventive, and condition-based maintenance strategies can also affect the overall performance of the system. The objective of this work is to investigate the possible trade-off between the configuration of a repairable k-out-of-n:G system...
The assessment and reduction of risk, utilizing the probabilistic safety assessment methodology, are the main prerequisites for improvement of safety in nuclear power plants. This need is even more emphasized nowadays due to the impact of ageing, since the number of safety systems components, that are approaching their wear-out stage, is rising fast. This study addresses the trade-off between risk...
An improved genetic algorithm on the basis of Gray encoding is presented, which is improved based on optimum maintenance of simple genetic algorithm and performs selected operator combination with fitness proportional model. The algorithm ensures the convergence property of genetic algorithm, and prevents premature phenomenon in some extent. In this paper, it is an example of the rolling shear mechanism...
Several disruptions (e.g., machine failure, quality problem, etc.) in a steel production often occur in practice and lead to a delay in the production. Many schedule changes in a short period of time lead to an unstable production. Therefore, a robust predictive scheduling, which takes the disruption effect into account, is a more suitable choice for handling the daily small disruption. In this paper,...
To realize the coordination between controlling the environmental risk caused by railway dangerous goods station (RDGS) and improving the efficiency of the whole dangerous goods transportation system, a bi-level programming model for optimizing the distribution of existing RDGSs is constructed concentrating on such two sub-problems as adjusting the location of existing RDGSs and adjusting their business...
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