36 research outputs found

    Permutation Flowshop Scheduling with Earliness and Tardiness Penalties

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    We address the permutation flowshop scheduling problem with earliness and tardiness penalties (E/T) and common due date of jobs. Large number of process and discrete parts industries follow flowshop type of production process. There are very few results reported for multi-machine E/T scheduling problems. We show that the problem can be sub-divided into three groups- one, where the due date is such that all jobs are necessarily tardy; the second, where the due date is such that it is not tight enough to act as a constraint on scheduling decision; and the third is a group of problems where the due date is in between the above two. We develop analytical results and heuristics for problems arising in each of these three classes. Computational results of the heuristics are reported. Most of the problems in this research are addressed for the first time in the literature. For problems with existing heuristics, the heuristic solution is found to perform better than the existing results.

    Planning and Scheduling Decisions in Supply Chains with Multiple Supply Modes: An Integrated Approach

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    We address the problem of jointly determining shipment planning and scheduling decisions with the presence of multiple shipment modes. We consider long lead time, less expensive sea shipment mode, and short lead time but expensive air shipment modes. Existing research on multiple shipment modes largely address the short term scheduling decisions only. Motivated by an industrial problem where planning decisions are independent of the scheduling decisions, we investigate the benefits of integrating the two sets of decisions. We develop sequence of mathematical models to address the planning and scheduling decisions. Preliminary computational results indicate improved performance of the integrated approach over some of the existing policies used in real-life situations.Singapore-MIT Alliance (SMA

    Permutation Flowshop Scheduling with Earliness and Tardiness Penalties

    No full text
    We address the permutation flowshop scheduling problem with earliness and tardiness penalties (E/T) and common due date of jobs. Large number of process and discrete parts industries follow flowshop type of production process. There are very few results reported for multi-machine E/T scheduling problems. We show that the problem can be sub-divided into three groups- one, where the due date is such that all jobs are necessarily tardy; the second, where the due date is such that it is not tight enough to act as a constraint on scheduling decision; and the third is a group of problems where the due date is in between the above two. We develop analytical results and heuristics for problems arising in each of these three classes. Computational results of the heuristics are reported. Most of the problems in this research are addressed for the first time in the literature. For problems with existing heuristics, the heuristic solution is found to perform better than the existing results.

    Coordination of planning and scheduling decisions in global supply chains with dual supply modes

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    We address the problem of coordinating aggregate planning decisions and short-term scheduling decisions in supply chains with dual supply modes. We consider long lead time, less expensive sea shipments that are based on demand forecast, and responsive but costly air shipments that are based on revised forecast closer to the demand period. The planning problem determines the sea shipment order quantity and inventory level, while the scheduling model determines the schedule and quantity of air shipments. Results from our numerical experiments suggest that our model leads to consistent cost improvements over a wide range of operating scenarios.Coordination Dual supply modes Planning Scheduling

    Evaluation of peri-implant parameters and c-reactive protein levels among patients with different obesity levels

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    Background: Assessment of correlation between peri-implant parameters and C-reactive protein levels among patients with different obesity levels. Materials and Methods: Evaluation of 60 subjects was performed who were scheduled to undergo dental implant therapy for missing mandibular first molars. Three study cohorts were formed, namely, Group A: obese group (BMI between 30 Kg/m2 and 34.9 Kg/m2), Group B: high obese group (BMI over 34.9 Kg/m2), and Group C: non-obese group (BMI under 25 Kg/m2). Each cohort comprised 20 subjects. Dental implant therapy was carried out in all the patients. Peri-implant variables were evaluated in all the patients. Blood samples were obtained, and C-reactive protein levels in subjects having different obesity levels. Statistical analysis was performed using SPSS software. Results: Mean serum C-reactive protein levels among patients of groups A, B, and C occurred to be 3.28 mg/L, 3.65 g/L, and 3.61 g/L, respectively. On comparing numerically, noticeable outcomes were achieved. Mean probing depth among subjects of groups A, B, and C occurred to be 2.9 mm, 3.2 mm, and 1.3 mm, respectively. Mean marginal bone loss among subjects of groups A, B, and C occurred to be 2.1 mm, 2.7 mm, and 0.8 mm, respectively. On comparing numerically, noteworthy outcomes were gathered. Conclusion: There were significantly higher deranged peri-implant inflammatory variables among patients with higher levels of obesity

    Optimal blood pressure in patients with atrial fibrillation (from the AFFIRM Trial).

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    Many medications used to treat atrial fibrillation (AF) also reduce blood pressure (BP). The relation between BP and mortality is unclear in patients with AF. We performed a post hoc analysis of 3,947 participants from the Atrial Fibrillation Follow-Up Investigation of Rhythm Management trial. Systolic blood pressure (SBP) and diastolic blood pressure (DBP) at baseline and follow-up were categorized by 10-mm Hg increments. The end points were all-cause mortality (ACM) and secondary outcome (combination of ACM, ventricular tachycardia and/or fibrillation, pulseless electrical activity, significant bradycardia, stroke, major bleeding, myocardial infarction, and pulmonary embolism). SBP and DBP followed a U-shaped curve with respect to primary and secondary outcomes after multivariate analysis. A nonlinear Cox proportional hazards model showed that the incidence of ACM was lowest at 140/78 mm Hg. Subgroup analyses revealed similar U-shaped curves. There was an increased ACM observed with BP \u3c110/60 mm Hg (hazard ratio 2.4,
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