Production Lot Research Articles

Validation of PhageDx™ Cronobacter Assay for the Identification of Cronobacter Spp. in Powdered Infant Formula: AOAC Performance Tested MethodSM 051803.

BackgroundThe PhageDx™Cronobacter Assay is based on the infection of Cronobacter spp. by specific bacteriophages and expression of a luciferase reporter gene. Results are generated in as little as 18.5 h for powdered infant formula (PIF).ObjectiveAn AOAC Performance Tested MethodsSM (PTM) study was conducted to validate the PhageDx Cronobacter Assay for the detection of Cronobacter in 10, 100, and 300 g milk- and soy-based PIF test portions.MethodThe performance of the PhageDx method was compared to the ISO 22964:2006/2017 Microbiology of the Food Chain—Horizontal Method for the Detection of Cronobacter spp. and the U.S. Food and Drug Administration (FDA) Bacteriological Analytical Manual (BAM) Chapter 29 Cronobacter: 2012. Inclusivity/exclusivity, product consistency and stability, and robustness testing also were conducted.ResultsThere was no significant difference between the 10, 100, or 300 g test portions for the milk and soy PIF matrixes between the PhageDx Cronobacter Assay, the ISO 22964:2006/2017, and the FDA BAM Chapter 29 Cronobacter: 2012 methods. The reporter bacteriophages were specific for Cronobacter and infected 75 strains in inclusivity testing. They did not infect 35 non-Cronobacter bacteria in exclusivity testing. Robustness testing showed that the method performed well with specific deviations from the standard protocol. Consistency and stability testing demonstrated that the recombinant phage gave consistent results across three production lots and was stable when stored under appropriate conditions for at least 3 months.ConclusionsWork in the submitting and independent laboratories demonstrated that the PhageDx Cronobacter Assay meets the qualifications for PTM status.HighlightsThe PhageDx Cronobacter Assay is a rapid, simple, and specific test that has shown equivalence to both the FDA BAM and ISO reference methods for detecting Cronobacter spp. in PIF.

Validation of the PhageDx™ Listeria Assay for Detection of Listeria Spp. on Stainless Steel and Ceramic Environmental Surfaces AOAC Performance Tested MethodSM 102005.

BackgroundThe PhageDx™ Listeria Assay is a simple, specific, and sensitive assay based on the infection of Listeria spp. by selected bacteriophages and the resultant expression of a luciferase reporter gene. Results are generated in as little as 24.5 h for stainless steel and ceramic environmental surfaces.ObjectiveAn AOAC Performance Tested MethodsSM (PTM) study was conducted to validate the PhageDx Listeria Assay for the detection of Listeria on stainless steel and ceramic surfaces.MethodThe performance of the PhageDx method was compared to that of the U.S. Food and Drug Administration (FDA) Bacterial Analytical Manual (BAM) Ch. 10. Inclusivity/exclusivity, product consistency and stability, and robustness testing also were conducted.ResultsInclusivity testing demonstrated that the reporter bacteriophages were specific for Listeria ssp. and detected 58/61 Listeria strains tested, including all 34 L. monocytogenes strains. The reporter bacteriophage also was shown to not detect 46/47 non-Listeria bacteria in exclusivity testing. Robustness testing showed that the method performed well with specific deviations from the standard protocol. Consistency and stability testing demonstrated that the recombinant phage gave consistent results across three production lots and was stable when stored under appropriate conditions for at least 6 months. Matrix studies on stainless steel and ceramic surfaces showed that there was no significant difference between the PhageDx Listeria Assay and the FDA/BAM Chapter 10 reference method.Conclusions and HighlightsThe validation study demonstrates that the PhageDx Listeria Assay is an effective method for the detection of Listeria spp. on stainless steel and ceramic environmental surfaces and meets the qualifications for AOAC PTM status.

Postmortem Aging Time and Marbling Class Effects on Flavor of Three Muscles From Beef Top Loin and Top Sirloin Subprimals

This study evaluated postmortem aging time and marbling class effects on flavor attributes of longissimus lumborum, gluteus medius, and biceps femoris steaks. Carcasses selected to have Lower Small (Small00 to Small49; n = 50) or Upper Slight (Slight50 to Slight99; n = 50) marbling were assigned to aging treatments (14, 21, 28, or 35 d) in an incomplete block arrangement. A trained sensory panel evaluated longissimus lumborum, gluteus medius, and biceps femoris steaks for tenderness, juiciness, and 31 flavor notes. Tenderness increases with aging time were linear (P < 0.001) in longissimus lumborum and gluteus medius steaks and quadratic (P = 0.001) in biceps femoris steaks. Aging response of rancid flavor in longissimus lumborum steaks was cubic (P = 0.01), whereas the aging response of bloody/serumy flavor in biceps femoris steaks was quadratic (P = 0.03). Compared with Upper Slight marbling, carcasses with Lower Small marbling produced longissimus lumborum steaks with greater (P < 0.01) beef flavor and lesser (P = 0.001) bitter flavor, gluteus medius steaks with greater (P = 0.05) brown/roasted flavor, and biceps femoris steaks with greater (P = 0.02) fat-like flavor, although differences were small. Principal component analysis indicated that bloody/serumy, sour, metallic, and bitter flavor attributes were the strongest contributors to a factor explaining 38% of longissimus lumborum flavor variation. Barnyard, bitter, sour, rancid, and bloody/serumy were the greatest contributors to a principal component explaining 41% of gluteus medius flavor. Barnyard, rancid, sour, bloody/serumy, and bitter were contributors to a component explaining 63% of biceps femoris sirloin cap flavor variance. Sample score plots indicated that neither aging time nor marbling class was associated with principal components and identified production lot as contributing to principal components explaining flavor variation in all 3 muscles. Results indicate that, in strip loin and top sirloin subprimals from carcasses with Upper Slight and Lower Small marbling scores, aging time and marbling class had little impact on beef flavor. Thus, increased aging times could be used to enhance tenderness with no adverse effects on other important palatability attributes.

Critical Analysis of Drug Product Recalls due to Nitrosamine Impurities.

A product recall is the outcome of a careful pharmacovigilance; and it is an integral part of drug regulation. Among various reasons for product recall, the detection of unacceptable levels of carcinogenic impurities is one of the most serious concerns. The genotoxic and carcinogenic potential of N-nitrosamines raises a serious safety concern, and in September 2020, the FDA issued guidance for the pharmaceutical industry regarding the control of nitrosamines in drug products. The FDA database shows that >1400 product lots have been recalled from the market due to the presence of carcinogenic N-nitrosamine impurities at levels beyond the acceptable intake limit of 26.5 ng/day. The drugs that were present in recalled products include valsartan, irbesartan, losartan, metformin, ranitidine, and nizatidine. This perspective provides a critical account of these product recalls with an emphasis on the source and mechanism for the formation of N-nitrosamines in these products.

Evaluation of the In-Vitro Dissolution Permeation Systems 1 (IDAS1) as a potential tool to monitor for unexpected changes in generic medicaments in poorly regulated markets

Panama, like most Latin American countries, has insufficient regulatory safeguards to ensure the safety and efficacy of all pharmaceutical products in the market, a situation that results in a two-tier system, where affluent citizens can afford innovator products while poor citizens must consume ‘generics’ of uncertain quality. Given that one lot of each drug product is analyzed every five years during registration while commercial lots are not, and since most products are not bioequivalent but simply copies or similars, there is a concern that commercial and registration lots of these ‘generics’ may not be of the same quality. The objective of this study was to assess the ability of various in vitro quality control tests to detect difference among five amlodipine products available in the Panamanian market: four ‘generics’, made in various countries, and the innovator, made in Germany and used as reference listed drug in Panama (Pan-RLD). The innovator manufactured in the United States (US-RLD) was used to compare the two RLDs. The Content Uniformity test, 30-min Dissolution test and multiple-pH Dissolution Profiles did not show any difference among the products. However, the in vitro dissolution absorption system 1 (IDAS1) showed a statistically significant difference in the amount dissolved between Pan-RLD and three out of the four ‘generics’, and significantly lower permeated amount for all the ‘generics’ compared with Pan-RLD; only US-RLD was similar to Pan-RLD. Thus, IDAS1 showed promise as a potential tool that authorities in weakly regulated markets can use to monitor for possible lot-to-lot product changes, which can help improve the quality of pharmaceutical products available to their entire populations. The significance of the similarity between the innovators made in Germany and the United States and their difference from the ‘generics’ (manufactured in other countries) is not known but deserves investigation.

Efficacy and Safety of Clinical-Grade Human Vascular Endothelial Growth Factor-DΔNΔC Gene Therapy Containing Residual Replication-Competent Adenoviruses.

Biological bypass through induced angiogenesis by vascular endothelial growth factor D (VEGF-D) gene therapy (GT) is a new concept for the treatment of cardiac ischemia. Serotype 5 adenoviruses are used in the clinical trials for transferring the VEGF-D cDNA into the ischemic myocardium. However, the presence of replication-competent vectors in the adenovirus products is a widely recognized problem that may pose a potential safety risk to the treated patients. We compared three different VEGF-D GT production lots containing different levels of replication-competent adenoviruses (RCA) tested in 3 × 1010 viral particles (vp): <10 RCA (VEGF-D L-RCA1), 10-100 RCA (VEGF-D H-RCA2), and 100-200 RCA (VEGF-D H-RCA3), as measured by a novel droplet digital polymerase chain reaction (PCR) RCA assay in a preclinical rabbit model (n = 21). β-galactosidase encoding nonclinical-grade preparation was used as a nonangiogenic control. Each preparation was injected into the right semimembranosus muscle using dose of 1 × 1011 vp. Efficacy of the products was tested by the combination of contrast pulse sequencing ultrasound and modified Miles assay as well as quantifying the total cross-sectional area of capillaries. Safety, immunogenicity, toxicity, biodistribution, and shedding were assessed by general histology, serial measurements of C-reactive protein, white blood cell count and body temperature as well as using quantitative real-time PCR with primers targeted to the VEGF-D and replication-permitting E1 sequences. We found no significant differences in the efficacy or safety between the study groups. Most importantly, no detectable presence of RCA-specific E1 sequence was found in any samples tested, indicating that no detectable vector replication took place in vivo. We conclude that relatively low levels of RCA in adenoviral GT products may not be as important major safety issue as previously anticipated.

A Comparison of Three Methods for Determining Thermal Inactivation Kinetics: A Case Study on Salmonella enterica in Whole Milk Powder

Different methods for determining the thermal inactivation kinetics of microorganisms can result in discrepancies in thermal resistance values. In this study, thermal resistance of Salmonella in whole milk powder was determined with three methods: thermal death time (TDT) disk in water bath, pouches in water bath, and the TDT Sandwich system. Samples from three production lots of whole milk powder were inoculated with a five-strain Salmonella cocktail and equilibrated to a water activity of 0.20. The samples were then subjected to three isothermal treatments at 75, 80, or 85°C. Samples were removed at six time points and cultures were enumerated for survivors. The inactivation data were fitted to two consolidated models: two primary models (log linear and Weibull) and one secondary model (Bigelow). Normality testing indicated that all the model parameters were normally distributed. None of the model parameters for both consolidated models were significantly different (α = 0.05). The amount of inactivation during the come-up time was also not significantly different among the methods (α = 0.05). However, the TDT Sandwich resulted in less inactivation during the come-up time and overall less variation in model parameters. The survivor data from all three methods were combined and fitted to both consolidated models. The Weibull had a lower root mean square error and a better fit, according to the corrected Akaike's information criterion. The three thermal treatment methods produced results that were not significantly different; thus, the methods are interchangeable, at least for Salmonella in whole milk powder. Comparisons with more methods, other microorganisms, and larger varieties of food products using the same framework presented in this study could provide guidance for standardizing thermal inactivation kinetics studies for microorganisms in foods.

ISOLATION AND CHARACTERIZATION OF PIGMENT PRODUCING BACTERIA AND THEIR POSSIBLE USE IN TEXTILE INDUSTRY

The environment where we live is the habitat for various microorganisms, mostly bacteria which are used for various industrial applications like enzyme production, pharmaceutical production, fabric manufacturing and more. Colorants are used in lots of products including cosmetics, food and textiles. These colorants are synthetic and very harmful for humans. It is very harmful to environment because it contain toxic and non-biodegradable compounds. Now a days there is a growing demand for natural dyes which can be biodegradable and less harmful for the humans. Industry have lots of interest in microbial pigments, because they are more stable and soluble than pigments produced from plants and animals sources. It also can grow rapidly which will produce high yield throughout the year. Carotenoid are the very important compounds and are widely used in textile industry. Most of the fruits and vegetables contain carotenoids. These pigments have some limitations which include solubility, sensibility and instability on exposure to light, temperature and pH. The aim of the present study was to isolate pigment producing bacteria from three different soil samples. In this study yellow and orange pigmented bacteria were isolated and developed in to pure culture. Morphological and biochemical characterization was carried out and these isolates were observed for maximun pigment production at diffrent pH, Temperature and NaCl Concentrations. Yellow and Orange colour bacterial extracts of carotenoids pigments were extracted and used as natural colorants for dying of cloth. The present study indicated that pigment production was influenced by physical factors such as pH, Temperature and NaCl. Absorbance of carotenoids pigments were tested by using UV-Visible spectroscopy and these pigments shows a promising result in textile industry as natural colorants.

Identification and Traceability of Spiritous Drinks based on UV-spectrometry and Conductometry

This article is devoted to the identification and detection of adulterated alcoholic beverages on the example of brandy and vodka. According to different opinions, up to 40% of spiritous beverages turn out to be adulterated or counterfeit. Most commonly used to identify such adulteration analytical methods are either too expensive or time-demanding. The other important thing that there is no standard method developed for objective tracing of spirits to the level of a production lot. The paper proposes an express method for detecting adulterated alcoholic beverages based on the use of two analytical methods of different nature: conductometry and UV-spectrometry. The possibility of these methods’ joint use for identification of alcoholic beverages with the standard or by common features (non-signature identification) is proved by the usage of statistical methods on data got from analytical measurements and sensory evaluation of 171 drinks’ samples. The samples represent different countries of product origin, brands, ageing periods. Firstly we found out informative wavelength bands, spectral curve forms and conductivity limits for different types of drinks, both genuine and adulterated – adulteration was previously revealed by sensory test. Then, using k-means cluster analysis we developed typical spectra for 2 ‘styles’ of genuine brandies and adulterated brandies, for vodkas the same work was done using simpler statistical techniques (means and variation analysis). Finally, an algorithm for spiritous beverages identification and tracing is given. Additionally, changes in the values of the electrical conductivity and UV spectra during shelf life that do not affect the suitability of the proposed method were studied.

Using a next-generation sequencing approach to DNA metabarcoding for identification of adulteration and potential sources of mercury in commercial cat and dog foods.

Studies have demonstrated that some commercial pet (i.e., cat and dog) food products contain high concentrations of mercury (Hg), and some products have Hg concentrations that are higher than expected based on the ingredients included in the package ingredient list. Additionally, concentrations of methylmercury, a particularly toxic form of Hg commonly associated with fish-based ingredients, are largely unstudied despite the widespread use of such ingredients in pet food products. This study aimed to quantify total Hg and methylmercury in a variety of commercial pet food products (n=127), and use genetic tools to determine if specific ingredients contributed to high Hg concentrations in the final product. Results indicate that total Hg concentrations were above suggested maximum tolerable limits in three of the tested pet food products, and that methylmercury concentrations were at safe levels in all tested products. Next-generation amplicon sequencing using ten barcode primers was conducted to target distinct taxa and to determine if one primer set outperformed the others in amplifying the often heavily degraded DNA found in pet food products. The 16sUniF_16sUniR primer set generated a relatively higher number of reads across the broadest set of taxa, although several of the primer sets were useful in identifying common animal- and plant-based ingredients in commercial pet food products. Combined with the Hg results, it was demonstrated that pet food product ingredients are consistent among and between product lots. However, these results also revealed that adulteration is prevalent in pet food products.

Eco-Efficiency of Pencil Preduction Using Life Cycle Assessment to Increase the Manufacture Sustainability

This study aims to measure the environmental costs (eco-cost) and the eco-efficiency ratio rate (EER) of the production of pencils and formulate some recommendations to improve the manufacture sustainability. The measurement of Eco-efficiency was performed using life cycle assessment (LCA) with the eco-cost method. The pencil manufacturer produces a waste of 20 %, and the product rejects 37 %. The material used is wood, slat, and chemical material for painting. The result of the data processing shows that the eco-costs of IDR 50.593.583 for 4200 grosses production lot size. The eco-efficiency index or EEI for pencil product was 1,69, which means that the products are affordable and sustainable. The eco-efficiency ratio rate (EER) is 41% means that pencil production processes need improvement. The single score Impact Category Diagram shows that the most significant environment impact category is climate change. The recommendation to improve the EER of pencil production based on Impact Category Diagram is (1) to increase the utilizing of wood waste and (2) to increase the capability of technicians and operators to reduce the product rejection. These recommendations aim to reduce the wood consumed in production.

Optimum profit model based on the average outgoing quality limit protection

The optimal setting of process mean is an important issue in operations management and a variable sampling inspection plan is an acceptance sampling technique for quality assurance. In the present study, the newsvendor problem (i.e., the mixed procurement system) is modified by applying a variable sampling inspection plan with specified average outgoing quality limit (AOQL) with maximization of the expected total profit including the manufacturer and the retailer. The optimal retailer’s order quantity and manufacturer’s process mean and the parameters of sampling plan are jointly determined by maximizing the expected total profit. In the model, the single sampling rectifying inspection plan is adopted to determine the quality of lot product and the used cost of customer for product is measured by Taguchi’s quadratic loss function. A numerical example is given and the sensitivity analysis of model parameters are provided for illustration. Based on the results of sensitivity analysis, it may be seen that a higher processing cost per unit generally leads to a lower expected profit. In the meantime, a higher retailer’s selling price always results in a higher expected profit.

Material Requirements Planning Under Demand Uncertainty Using Stochastic Optimization

Material Requirements Planning (MRP), a core component of enterprise resource planning (ERP) systems, is widely used by manufacturers to determine the production lot sizes of components. These lot sizes are typically computed based on deterministic and dynamic demand assumptions, while safety stocks, which hedge against demand uncertainty, are determined independently based on different assumptions. As the lot sizes and safety stocks are not determined simultaneously, sub‐optimal decisions are often used in practice. The critical impact of inventories and service levels in manufacturing motivates the study of stochastic optimization methods for MRP. In this study, we investigate stochastic optimization methods for MRP systems under demand uncertainty. A two‐stage and a multi‐stage model are proposed to deal with the static‐static and static‐dynamic decision frameworks, respectively. We first derive structural properties of the two‐stage and multi‐stage models to provide insights on the differences between the plans created with these two models. As multi‐stage stochastic programs are not convenient in real‐world applications, several practical enhancements are proposed. First, to address scalability issues, we employ heuristics in combination with advanced sampling methods. Second, to allow real‐time static‐dynamic decisions, we derive a policy from the solution of the multi‐stage model. Third, to deal with the dynamic‐dynamic decision framework, we employ a rolling horizon implementation. The effectiveness and performance of stochastic optimization for MRP are validated by numerical experiments, which demonstrate that the stochastic optimization approaches have the potential to generate significant cost savings compared to traditional methods for production planning and safety stocks determination.

Joint optimization of lot sizing and condition-based maintenance for a production system using the proportional hazards model

This paper optimizes economic production quantity (EPQ) and condition-based maintenance (CBM) simultaneously for a production system subject to aging and deterioration. Different from previous models jointly determining EPQ and CBM, the proposed model is developed based on the proportional hazards model with a continuous-state covariate process, and on a CBM policy with multiple maintenance actions and dynamic control limits. Taking advantage of the opportunity of the downtime when a production run completes, condition monitoring is performed to reveal the system deterioration and then a suitable action is selected from preventive replacement, preventive repair, and no maintenance. Random failures during a production phase can be fixed by corrective replacement, corrective repair, or minimal repair. Considering that in many practical situations condition monitoring cannot be conducted at failure, corrective maintenance actions are determined based on (1) the system age at failure and the deterioration at the beginning of the production run (Scenario 1); or (2) both the system age and deterioration at the beginning of the production run (Scenario 2). The objective is to jointly optimize the production lot size and the CBM policy by minimizing the long-run average cost rate. The optimization problem is solved based on the policy-iteration algorithm in the semi-Markov decision process (SMDP) framework. A numerical example is provided to illustrate the proposed approach. The results show that Scenario 1 produces a more cost-effective but more complex maintenance strategy than Scenario 2 does.

The Accuracy of Finishing WEDM of Inconel 718 Turbine Disc Fir Tree Slots.

Servicing aircraft engines sometimes requires manufacturing only a single piece of a given part. Manufacturing a turbine disc using traditional methods is uneconomical. It is necessary to use a different machining method recommended for small lot production. One of the proposed methods is WEDM (wire electrical discharge machining). The article presents the results of the research on finishing WEDM of Inconel 718 turbine disc fir tree slots. The influence of infeed, mean gap voltage, peak current, pulse off-time, and discharge energy on the shape accuracy, surface roughness, microcracks, and the white layer thickness were determined. Mathematical models were developed based on the DoE (Design of Experiment) analysis. The statistical significance of the models was verified with the ANOVA (Analysis of Variance) test. The machining parameters control methods that allow achieving the required shape accuracy, surface roughness, and surface layer condition were presented. The obtained surface roughness was Ra = 0.84 μm, the shape accuracy of the slot in the normal-to-feed direction was Δd = 0.009 μm, the profile shape accuracy was Δr = 0.033 μm, and the thickness of recast (white) layer was approximately 5 μm.

Ordering Depletion in Inventory Policy with Imperfect Products and Backorder Rebate

This study presents an inventory model for imperfect products with depletion in ordering costs and constant lead time where the price discount in the backorder is permitted. The imperfect products are refused or modified or if they reached to the customer, returned and thus some extra costs are experienced. Lately some of the researchers explicitly present on the significant association between size of lot and quality imperfection. In practical situations, the unsatisfied demands increase the period of lead time and decrease the backorders. To control customers' problems and losses, the supplier provides a price discount in backorders during shortages. Also, an order’s policies may result in including some imperfect products in arrival lots. A discount on price may be offered by the supplier on the out-of-stock products to manage the backorder problems. The study aims to develop a model with imperfect products by permitting the price discount in backorders, and the cost of ordering is considered a decision variable. First, it is assumed that the demand for lead time is followed by a normal distribution and then stops it and assumed that the first two moments of demand for lead time are known. Further, the minimax distribution method is used to solve this model, and a separate algorithm is designed. In this study, two models are discussed with and without a normally distributed rate of demand. The current study verified with the help of some numerical examples over various model parameters.

The effect of transfer lot size on manufacturing lead time: a stochastic analysis

This paper aims to explore, in a quantitative way, the effect of production and transfer lot size on the manufacturing lead time in an environment subject to uncertainties. In order to achieve this...

Production rate and lot-size dependent lead time reduction strategies in a supply chain model with stochastic demand, controllable setup cost and trade-credit financing

This study explores simultaneous reduction strategies of lead time and setup cost in a two-stage supply chain model under trade-credit financing. Lead time depends on a variable production rate and lot size. It consists of setup, production, and transportation time which are shortened to reduce lead time. Although double safety factors are considered to avoid stock-out; but still backorders take place as the demand during the lead time is stochastic. Setup cost is reduced by including an extra investment cost. In addition, the vendor offers a fixed credit period to the buyer to settle the account. The objective is to minimize the integrated expected total cost and optimize the order quantity, number of deliveries, setup and transportation time, setup cost, safety factor for the first batch, and the production rate. A multi-variable optimization technique is used for these purposes. Furthermore, a numerical example together with managerial insights is provided for the establishment and applicability of the proposed model. The numerical results show that the introduction of setup cost reduction and trade-credit financing along with lead time reduction is more beneficial by means of integrated expected total cost reduction.

An integrated process targeting and continuous review system with sampling inspection

It is common in the integrated targeting inventory literature to assume 100% inspection. Yet, sampling inspection is still a valid alternative in numerous situations. Inspection time has been assumed negligible in the literature of integrated inventory and sampling inspection. Neglecting inspection time is unrealistic, especially when rejected lots are sent for 100% inspection. This research work integrates process targeting, production lot-sizing and inspection. Given a scenario of a producer and distributer, the objective is to determine the optimal mean setting at the producer, the production lot size to be produced and shipped to the distributor and the reorder point at the distributor under a given sampling inspection plan. To the best of the authors’ knowledge, sampling inspection and its associated costs are rarely addressed in integrated supply chain models, and have never been addressed in integrated models with controllable production rates. Numerical illustrations using an efficient solution technique are presented to highlight the impact of various model parameters. The results indicated that inspection time has a significant impact on the total cost of the developed model, especially, when tightened inspection plans are used.

Random machine breakdown and stochastic corrective maintenance period on an economic production inventory model with buffer machine and safe period

In this paper, we have developed an economic production quantity (EPQ) model in which production is executed mainly by the original machine. But when the system faces disruption, the buffer of it continues the production. Here, we incorporate a fixed Safe Period running policy, in which the machine runs interruptedly, whenever production commences. The disruption of the system may occur at any moment of the time horizon over the safe period, and then, it will go under the corrective maintenance policy. Here, we take that both of the time of disruption and period of maintenance are continuous random variables. We have discussed the model under different safe period duration with corresponding disruption situations. Our main objective is to minimize the expected average total cost for all the cases concerning the production lot size. The model has also been illustrated numerically with some examples. To examine the robustness of the solution of this model, we discuss the sensitivity analysis for the parameters.