scholarly journals Production-Inventory System for Deteriorating Items with Machine Breakdown, Inspection, and Partial Backordering

Mathematics ◽  
2019 ◽  
Vol 7 (7) ◽  
pp. 616 ◽  
Author(s):  
Kung ◽  
Huang ◽  
Wee ◽  
Daryanto
Keyword(s):  
Sensitivity Analysis ◽  
Deteriorating Items ◽  
Defective Items ◽  
Machine Breakdown ◽  
Partial Backordering ◽  
Imperfect Items ◽  
Production Inventory ◽  
Before And After ◽  
Replenishment Policy ◽  
Renewal Reward Theorem

This study considers the effects of a machine breakdown, inspection, and partial backordering for deteriorating items. Most industries try to reduce facility unavailability by implementing a regular inspection and preventive maintenance since there is a possibility that some machines will breakdown during the production process. Moreover, an emergency purchase policy can be provided for quick response to customer’s backorder. The system also produces imperfect items with different rates before and after the inspection. Rework process and post-sales warranty are launched for the defective items. Unlike previous studies, we applied a fixed-point approach and renewal reward theorem to solve the deteriorating production-inventory model while considering machine breakdown, inspection, and partial backordering. A case example and sensitivity analysis are provided. The sensitivity analysis shows the important parameters that should be considered in designing the inspection plan and the replenishment policy when facility unavailability and imperfect items exist.

scholarly journals An Inventory Model with Time-Dependent Demand and Limited Storage Facility under Inflation

2012 ◽  
Vol 2012 ◽  
pp. 1-17 ◽  
Author(s):  
Neeraj Kumar ◽  
S. R. Singh ◽  
Rachna Kumari
Keyword(s):  
Sensitivity Analysis ◽  
Cash Flow ◽  
Inventory Model ◽  
Problem Analysis ◽  
Present Value ◽  
Discounted Cash Flow ◽  
Deterioration Rate ◽  
Partial Backordering ◽  
Replenishment Policy ◽  
Dependent Demand

The main objective of this paper is to develop a two-warehouse inventory model with partial backordering and Weibull distribution deterioration. We consider inflation and apply the discounted cash flow in problem analysis. The discounted cash flow (DCF) and optimization framework are presented to derive the optimal replenishment policy that minimizes the total present value cost per unit time. When only rented or own warehouse model is considered, the present value of the total relevant cost is higher than the case when two-warehouse is considered. The results have been validated with the help of a numerical example. Sensitivity analysis with respect to various parameters is also performed. From the sensitivity analysis, we show that the total cost of the system is influenced by the deterioration rate, the inflation rate, and the backordering ratio.

scholarly journals Sustainable Inventory Management for Environmental Impact through Partial Backordering and Multi-Trade-Credit-Period

2018 ◽  
Vol 10 (12) ◽  
pp. 4761 ◽  
Author(s):  
Biswajit Sarkar ◽  
Waqas Ahmed ◽  
Seok-Beom Choi ◽  
Muhammad Tayyab
Keyword(s):  
Environmental Impact ◽  
Inventory Management ◽  
Trade Credit ◽  
Global Business ◽  
Numerical Illustration ◽  
Defective Items ◽  
Credit Period ◽  
Partial Backordering ◽  
Imperfect Items ◽  
Total Profit

Incorporation of sustainable management for the rework of defective items brings long lasting benefits. In global business, there are situations when the products are procured from a global supplier. There are chances that the received lot may contain a fraction of imperfect products. These imperfect products are still valuable and can be repairable to save the environment. It is sustainable to repair imperfect items in a local repair store as compared to sending it back to the supplier. The cost of carbon emissions is also incorporated in the function to incorporate the environmental impact on total profit. Meanwhile, the supplier also offers a multi-trade-credit-period to the buyer. The developed model is sustainable and reduces the environmental impact as well as benefits for interim financing. This paper has an objective to maximize the total profit by developing a synergic economic order quantity model by considering multi-trade-credit policy, rework, and shortages simultaneously. This model can help in making decisions to enhance the performance of sustainable inventory management by controlling the cycle time and a fraction of time for a global supply chain. A non-derivative approach is employed to develop a closed-form optimal result. The numerical illustration with sensitivity analysis is also drawn to provide managerial insights into real practices.

Algebraic modelling of a two level supply chain with defective items

2018 ◽  
Vol 52 (2) ◽  
pp. 415-427 ◽  
Author(s):  
Mohamed E. Seliaman ◽  
Mehmood Khan ◽  
Leopoldo Eduardo Cárdenas-Barrón
Keyword(s):  
Sensitivity Analysis ◽  
Supply Chain ◽  
Cycle Time ◽  
Differential Calculus ◽  
Coordination Mechanisms ◽  
Algebraic Solution ◽  
Two Stage ◽  
Defective Items ◽  
Imperfect Items ◽  
Algebraic Modelling

M. Khan and M.Y. Jaber, Optimal inventory cycle in a two-stage supply chain incorporating imperfect items from suppliers. Int. J. Oper. Res. 10 (2011) 442–457, have addressed a two level supply chain of defective items. They compared three coordination mechanisms, i.e. cycle time; K–multiplier cycle time; and 2K–multiplier cycle time. This paper proposes a simpler algebraic solution for the K–multiplier cycle time mechanism without the use of differential calculus. The two level supply chain with defective items is illustrated with a numerical example. A sensitivity analysis is also provided.

scholarly journals Robust Inferences from a Before-and-After Study with Multiple Unaffected Control Groups

2013 ◽  
Vol 1 (2) ◽  
pp. 209-234 ◽  
Author(s):  
Pengyuan Wang ◽  
Mikhail Traskin ◽  
Dylan S. Small
Keyword(s):  
Sensitivity Analysis ◽  
Control Groups ◽  
Two Stage ◽  
Time Effects ◽  
Unaffected Control ◽  
Group Time ◽  
Before And After ◽  
Group Variation ◽  
The Impact ◽  
Before And After Study

AbstractThe before-and-after study with multiple unaffected control groups is widely applied to study treatment effects. The current methods usually assume that the control groups’ differences between the before and after periods, i.e. the group time effects, follow a normal distribution. However, there is usually no strong a priori evidence for the normality assumption, and there are not enough control groups to check the assumption. We propose to use a flexible skew-t distribution family to model group time effects, and consider a range of plausible skew-t distributions. Based on the skew-t distribution assumption, we propose a robust-t method to guarantee nominal significance level under a wide range of skew-t distributions, and hence make the inference robust to misspecification of the distribution of group time effects. We also propose a two-stage approach, which has lower power compared to the robust-t method, but provides an opportunity to conduct sensitivity analysis. Hence, the overall method of analysis is to use the robust-t method to test for the overall hypothesized range of shapes of group variation; if the test fails to reject, use the two-stage method to conduct a sensitivity analysis to see if there is a subset of group variation parameters for which we can be confident that there is a treatment effect. We apply the proposed methods to two datasets. One dataset is from the Current Population Survey (CPS) to study the impact of the Mariel Boatlift on Miami unemployment rates between 1979 and 1982.The other dataset contains the student enrollment and grade repeating data in West Germany in the 1960s with which we study the impact of the short school year in 1966–1967 on grade repeating rates.

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