Reactive Schedule Repair of Job Shops

Disruptions to job shop schedules are tedious and difficult to incorporate after the schedule has been generated and implemented on the shop floor. In order to deal with such disruptions, a real time reactive scheduling strategy is essential. Reactive scheduling is the process of repairing the predictive schedule during online execution for internal disruptions (e.g. machine breakdowns) and external deviations (e.g. prepone or postpone of orders). Existing approaches for schedule repair in real time mainly utilize heuristics such as Right Shift Rescheduling (RSR), and Affected Operation Rescheduling (AOR). In the present form, both these approaches are only used for handling machine breakdowns in the shop floor, but are inept in accommodating new and unexpected job orders. These approaches also neglect specific issues related to urgent jobs, for instance multiple job routings during the repair of the schedule. In this paper the existing heuristics (RSR and AOR) have been modified to include urgent jobs. Also a modified AOR approach (mAOR) is proposed that considers urgent jobs with multiple job routings. An extensive simulation study has been conducted on a job shop simulation testbed for the efficiency and stability of the repaired schedule using the mAOR and RSR heuristics. The efficiency of the repaired schedule is a measure of the percentage change in the makespan after incorporating repairs whereas the stability of the schedule is a function of starting time deviations that indicate the degree by which it deviates from the original schedule. The results of the experiments indicate significant benefits of the modified AOR algorithm over the existing RSR schedule repair heuristic.Singapore-MIT Alliance (SMA

Scheduling of manufacturing systems based on extreme value theory and genetic algorithms

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 1995.Includes bibliographical references (p. 143-154).by Velusamy Subramaniam.Ph.D

Setting Real Time WIP Levels in Production Lines

A new algorithm is developed for setting WIP level in production lines. It is a pull policy that determines when to authorize a job to be processed. Dynamic information in the system such as machine failures and repairs, and demand variations are taken into consideration to provide an efficient method to dynamically determine the WIP level. Two types of production lines are examined in this paper. The first is production lines which have few random interruptions and the second production line is exposed to frequent interruptions. Experiment results from these two types of production lines illustrate that the new algorithm generates higher service level with lower WIP compared to the CONWIP policy. In addition, the superiority of the new algorithm is more significant when the production line is exposed to frequent random interruptions.Singapore-MIT Alliance (SMA

Dynamic Scheduling of Flexible Manufacturing Systems

To date, group scheduling research has primarily focused on examining the performance of different group heuristics under various experimental conditions. However, the dynamic selection of group heuristics has not received sufficient attention from researchers. The objective of this paper is to demonstrate a mechanism for the dynamic selection of group heuristics from several candidate alternatives by exploiting real time information from the Flexible Manufacturing System (FMS). In this regard, two tools, viz., Analytic Hierarchy Process (AHP) and Simple Multi-Attribute Rating Technique Exploiting Ranks (SMARTER), are used to develop models for part type and family selection. The experimental results indicate that the performance of the proposed models are better than the common group scheduling heuristics under varied experimental conditions.Singapore-MIT Alliance (SMA

A Generic Mechanism for Repairing Job Shop Schedules

Reactive repair of a disrupted schedule is a better alternative to total rescheduling, as the latter is a time consuming process and also results in shop floor nervousness. The schedule repair heuristics reported in the literature generally address only machine breakdown. This paper presents a modified Affected Operations Rescheduling (mAOR) approach, which deals with many of the disruptions that are frequently encountered in a job shop. The repair of these disruptions has been decomposed into four generic repair actions that can be applied singularly or in combination. These generic repair actions are evaluated through a simulation study with the performance measures of efficiency and stability. The results indicate the effectiveness of the mAOR heuristic in dealing with typical job shop disruptions.Singapore-MIT Alliance (SMA

Trending Advancements in Technologies Pertinent to Therapeutical Pharmacodynamics

It is omniscient that pharmacodynamics of a drug is understood as its effect on body by interacting with the structure of targets to either activate or inhibit their function/action. Based on the activity of the drug to the target binding site they have been classified into different types. Physiological, cellular, molecular, biochemical, and toxicological effects individually have a significant role in drug’s effect and response. The mechanism of action, dosage and its response, therapeutic index are some of the noteworthy parameters to be considered in drug pharmacodynamics. This chapter comprehends the above-mentioned concepts, their importance in pharmacodynamics of drug, and the impact of recently developed methods like genome-wide or transcriptome-wide sequencing, chronopharmacodynamics, systems biology, pharmacometabolomics, etc., in different stages of drug discovery process, and how the digitization of therapeutics and healthcare direct the path to personalized medicine. The integration of bioinformatics, systems biology, and big data related approaches like ML & AI with the pharmacological (PK/PD) study highly benefits the patients’ therapeutics

Analysis of a two-stage, flexible production system with unreliable machines, finite buffers and non-negligible setups

10.1007/s10696-011-9115-2Flexible Services and Manufacturing Journal253414-44