Parallel-Machine Scheduling Problems with Past-Sequence-Dependent Delivery Times and Aging Maintenance

We consider parallel-machine scheduling problems with past-sequence-dependent (psd) delivery times and aging maintenance. The delivery time is proportional to the waiting time in the system. Each machine has an aging maintenance activity. We develop polynomial algorithms to three versions of the problem to minimize the total absolute deviation of job completion times, the total load, and the total completion time

Derivation of a cost model to aid management of CNC machine tool accuracy maintenance

Manufacturing industries strive to produce improved component accuracy while not reducing machine tool availability or production throughput. The accuracy of CNC production machines is one of the critical factors in determining the quality of these components. Maintaining the capability of the machine to produce in-tolerance parts can be approached in one of two ways: run to failure or periodic calibration and monitoring. The problem is analogous to general machine tool maintenance, but with the clear distinction that the failure mode of general machine tool components results in a loss of production, whereas that of accuracy allows parts to be produced, which are only later detected as non-conforming as part of the quality control processes. This distinction creates problems of cost-justification, since at this point in the manufacturing chain, any responsibility of the machine is not directly evident. Studies in the field of maintenance have resulted in cost calculations for the downtime associated with machine failure. This paper addresses the analogous, unanswered problem of maintaining the accuracy of CNC machine tools. A mathematical cost function is derived that can form the basis of a strategy for either running until non-conforming parts are detected or scheduling predictive CNC machine tool calibrations. This is sufficiently generic that it can consider that this decision will be based upon different scales of production, different values of components etc. Therefore, the model is broken down to a level where these variables for the different inputs can be tailored to the individual manufacturer

Single machine scheduling with time-dependent linear deterioration and rate-modifying maintenance

We study single machine scheduling problems with linear time-dependent deterioration effects and maintenance activities. Maintenance periods (MPs) are included into the schedule, so that the machine, that gets worse during the processing, can be restored to a better state. We deal with a job-independent version of the deterioration effects, that is, all jobs share a common deterioration rate. However, we introduce a novel extension to such models and allow the deterioration rates to change after every MP. We study several versions of this generalized problem and design a range of polynomial-time solution algorithms that enable the decision-maker to determine possible sequences of jobs and MPs in the schedule, so that the makespan objective can be minimized. We show that all problems reduce to a linear assignment problem with a product matrix and can be solved by methods very similar to those used for solving problems with positional effects

Preventive Maintenance & Replacement Scheduling Model for Repairable and Maintainable Systems

Maintenance plan is required when there is a need to decide on production rate and preventive maintenance (PM) scheduling for complex production systems in industry. The more complex the system is, the more components that may fail and cause the entire piece of equipment to be taken out of service, that in turn could affect production rate. Usually, most of equipment has its PM schedule set during plant design phase and generally follow recommendation from equipment manufacturer. After years of operation (operation and maintenance phase), the PM schedule might not be optimised due to various reasons – lack of full information on failure rate, repair rate, maintenance cost, etc. Thus, the objectives of this project are to develop an appropriate model for preventive maintenance and replacement scheduling using Mixed Integer Non – Linear Programming (MINLP), and also to analyze the results and effectiveness of the optimized model through trade – offs curves, that are one of the project deliverables. The project is initiated by identifying problem and objectives, study on literature review regarding various types of preventive maintenance and replacement scheduling model, and then come out with a model concept. It was found out that various parametric change effects were observed in component age graphs and scheduling tables in two developed models. In Model 1, three different trends were seen for each three cases such as cost increment was observed as required reliability increased where no changes happened in required reliability when shutdown cost varied and required reliability increased when time period was decreased respectively. In Model 2, it can be also seen that as time period decreased required reliability increased where higher amount of given budget can also increase required reliability of components. After all, these studies should be useful for maintenance planners and engineers tasked with the problem of developing maintenance plans for complex systems of components

Combining time and position dependent effects on a single machine subject to rate-modifying activities

We introduce a general model for single machine scheduling problems, in which the actual processing times of jobs are subject to a combination of positional and time-dependent effects, that are job-independent but additionally depend on certain activities that modify the processing rate of the machine, such as, maintenance. We focus on minimizing two classical objectives: the makespan and the sum of the completion times. The traditional classification accepted in this area of scheduling is based on the distinction between the learning and deterioration effects on one hand, and between the positional effects and the start-time dependent effects on the other hand. Our results show that in the framework of the introduced model such a classification is not necessary, as long as the effects are job-independent. The model introduced in this paper covers most of the previously known models. The solution algorithms are developed within the same general framework and their running times are no worse than those available earlier for problems with less general effects

Continuous maintenance and the future – Foundations and technological challenges

High value and long life products require continuous maintenance throughout their life cycle to achieve required performance with optimum through-life cost. This paper presents foundations and technologies required to offer the maintenance service. Component and system level degradation science, assessment and modelling along with life cycle ‘big data’ analytics are the two most important knowledge and skill base required for the continuous maintenance. Advanced computing and visualisation technologies will improve efficiency of the maintenance and reduce through-life cost of the product. Future of continuous maintenance within the Industry 4.0 context also identifies the role of IoT, standards and cyber security

Working Notes from the 1992 AAAI Spring Symposium on Practical Approaches to Scheduling and Planning

The symposium presented issues involved in the development of scheduling systems that can deal with resource and time limitations. To qualify, a system must be implemented and tested to some degree on non-trivial problems (ideally, on real-world problems). However, a system need not be fully deployed to qualify. Systems that schedule actions in terms of metric time constraints typically represent and reason about an external numeric clock or calendar and can be contrasted with those systems that represent time purely symbolically. The following topics are discussed: integrating planning and scheduling; integrating symbolic goals and numerical utilities; managing uncertainty; incremental rescheduling; managing limited computation time; anytime scheduling and planning algorithms, systems; dependency analysis and schedule reuse; management of schedule and plan execution; and incorporation of discrete event techniques

Space Applications of Automation, Robotics and Machine Intelligence Systems (ARAMIS). Volume 1: Executive Summary

Potential applications of automation, robotics, and machine intelligence systems (ARAMIS) to space activities, and to their related ground support functions are explored. The specific tasks which will be required by future space projects are identified. ARAMIS options which are candidates for those space project tasks and the relative merits of these options are defined and evaluated. Promising applications of ARAMIS and specific areas for further research are identified. The ARAMIS options defined and researched by the study group span the range from fully human to fully machine, including a number of intermediate options (e.g., humans assisted by computers, and various levels of teleoperation). By including this spectrum, the study searches for the optimum mix of humans and machines for space project tasks

A process oriented approach to service concepts.

Cet article s’intéresse à l’amélioration de la qualité des services et à leur conception en discutant des concepts classiquement mobilisés dans l’analyse des services, au travers d’une approche orientée processus. Il commence par passer en revue les définitions proposées par quelques chercheurs bien connus, spécialistes des services. Il propose une nouvelle typologie des service basée sur une approche orientée processus, permettant de discuter la portée de certaines caractéristiques généralement associées aux services. Il pointe ensuite les similitudes existant entre la production de biens et celle de services et traite du continuum biens-services. Il s’intéresse enfin au clivage des opérations réalisées en front office et en back office, l’explicitation de la ligne de partage permettant de discuter de la qualité de service du double point de vue du consommateur et du producteur, dans une perspective de conception d’un service.The authors aim to contribute to the research on improvement of service quality and on service design by discussing service concepts through a process oriented approach. They begin by reviewing the service definitions given by some well known researchers working on service. They propose a new process oriented service classification which helps to challenge the validity of some service characteristics. They point out similarities between manufacturing and service production and discuss good-service continuum. They focus on separation of back-office operations from the front-office operations by the line of visibility which may help to discuss service quality from both producer's and customer's perspective in a service design context.Management de la production de services; Définition d'un service; Continuum produits-services; Classification des services; Coproduction;